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55193349 | Response Surface Analysis The three dimensional response surface plots can make predictive model equations more intuitive. Therefore, the surface response plot of the model is established and the influence of independent variables on the dependent variables is visualized through the adjustment of one factor at the same time (Samimi et al., 2015). In the present experiment, Fig. 6 and 7 showed the three-dimensional (3d) curved surface and twodimensional (2d) contour plot of the experiment. The influence of extraction temperature and extraction time on the total flavonoids extract yield was analyzed ( Fig. 6a and 7a). At a definite extraction time, increasing extraction temperature resulted an increase in extraction yield. However, when extraction temperature was higher than45°C the extraction yield was slightly decreased. It was similar for the extraction time. Therefore we can predict that the optimum extraction time is about 30 min and optimum extraction temperature is about 45°C. In addition, the effects of the extraction time and temperature on flavonoids extraction from walnut leaves were very significant. Figure 6b and 7b showed the 3D plot for the extraction yield of flavonoids from walnut leaves with respect to ethanol concentration and reaction temperature. With an increasing extraction temperature the extract yield slightly increased but as the temperature was exceeded 45°C the extract yield decreased extremely. When the extraction temperature was constant, the extraction yield increased with the ethanol concentration, then decreased slightly when the ethanol concentration is too high. The optimum ethanol concentration is about 70%. The influences of extraction time and ethanol concentration on the extraction yield of flavonoids were shown in the Fig. 6c and 7c. The extraction yield increased with the increase in ethanol concentration, however when ethanol concentration was higher than 70%, the extraction yield of flavonoids tend to be stable and slightly decreased. When the concentration of ethanol was constant, the extraction yield of total flavonoids increased with extraction time, as extraction time reached 30 min the best extraction yield was attainted. While extract yield slightly decreased with the extraction time exceeded 30 min. We can conclude that the optimum extraction time is about 30 min and the optimum ethanol concentration is about 70%. The Antibacterial Activity Analysis Antimicrobial activities of the flavonoids extracts from walnut leaves were tested against selected microorganisms (Table 4). The results indicated that the flavonoids obtained from walnut leaves have antibacterial activity at 100mg/mL −1 and the bacterial inhibition ring of flavonoids was measured. It indicated that the flavonoids have best antimicrobial activity against Staphylococcus aureusm, followed by Escherichia coli and then Salmonella typhi. MIC of the extracts recorded was in the range of 12.5-50 mg/mL (Table 5). In this investigation the MIC value of 12.5 mg/mL was recorded for Escherichia coli and Staphylococcus aureus. Whereas, MIC for Bacillus subtilis was 25 mg/mL and for Salmonella typhi was 50mg/mL, indicating that the walnut leave extracts have significant antimicrobial potential. Because the MIC of the extracts were very small, indicating they were highly efficient. An overview of the biological activity data obtained from the current survey can emphasize that the tested extracts have great potential for inhibiting bacteria. Staphylococcus aureus is of considerable importance because it is considered to be one of the main pathogens of many hospitals and community infections. | 18 |
29158677 | Intraoperative hemorrhage during pediatric craniofacial reconstruction and other surgical procedures can be significant and may exceed the circulating blood volume [1] mandating substantial perioperative transfusion. The intraoperative administration of antifibrinolytic agents is increasingly used to minimize blood loss and the need for transfusion [2]. Fibrin binding by tissue-type plasminogen activator and plasminogen is the key to the initiation of fibrinolysis. Plasmin is generated and cleaves fibrin, producing new C-terminal lysines, which serve to mediate positive feedback in the fibrinolytic cascade [3]. Downregulation of fibrinolysis in vivo occur through the action of carboxypeptidases, which remove C-terminal lysines [4]. The antifibrinolytic epsilon-aminocaproic acid (EACA) is a synthetic lysine analogue that blocks the lysine-binding sites on plasminogen, resulting in antifibrinolytic activity through inhibition of plasmin formation [5, 6] and ultimately clot stabiliziation. The objective of this investigation was to develop and validate a simple and selective liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the quantification of EACA in human plasma to support clinical pharmacokinetic studies of EACA in pediatric patients. There were several HPLC methods reported in the literature for analysis of EACA in biological samples. EACA was dansylated and measured by fluorescence detection [7] with an assay range of 50 to 1000 μg/mL in human serum. A similar HPLC-fluorimeter assay with a range of 62.5 to 1000 μg/mL was reported by Lacroix C et.al. [8]. An assay for EACA in plasJOURNAL OF APPLIED BIOANALYSIS, July 2015, p. 99-107. http://dx.doi.org/10.17145/jab.15.016 (ISSN 2405-710X) Vol. 1, No. 3 | 1 |
29158677 | Introduction Intraoperative hemorrhage during pediatric craniofacial reconstruction and other surgical procedures can be significant and may exceed the circulating blood volume [1] mandating substantial perioperative transfusion.The intraoperative administration of antifibrinolytic agents is increasingly used to minimize blood loss and the need for transfusion [2].Fibrin binding by tissue-type plasminogen activator and plasminogen is the key to the initiation of fibrinolysis.Plasmin is generated and cleaves fibrin, producing new C-terminal lysines, which serve to mediate positive feedback in the fibrinolytic cascade [3].Downregulation of fibrinolysis in vivo occur through the action of carboxypeptidases, which remove C-terminal lysines [4].The antifibrinolytic epsilon-aminocaproic acid (EACA) is a synthetic lysine analogue that blocks the lysine-binding sites on plasminogen, resulting in antifibrinolytic activity through inhibition of plasmin formation [5,6] and ultimately clot stabiliziation.The objective of this investigation was to develop and validate a simple and selective liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the quantification of EACA in human plasma to support clinical pharmacokinetic studies of EACA in pediatric patients.There were several HPLC methods reported in the literature for analysis of EACA in biological samples.EACA was dansylated and measured by fluorescence detection [7] with an assay range of 50 to 1000 µg/mL in human serum.A similar HPLC-fluorimeter assay with a range of 62.5 to 1000 µg/mL was reported by Lacroix C et.al.[8].An assay for EACA in plas-ma and urine after derivatization with o-phthalaldehyde and fluorescence detection was reported with an assay range of 50 to 250 µg/mL [9].One of the common challenges encountered with HPLC methods were separation of EACA from other naturally occurring amino acids in biological samples.Recently, a method was reported for analysis of EACA in ophthalmic formulation that utilized isocratic tandem-mode HPLC with reverse phase and strong cation exchange columns and an assay range of 500-1500 µg/mL [10].Previously, a LC-MS/ MS assay was reported for analysis of caprolactam and EACA in human urine [11].Assay range for EACA was 62.5-1000 ng/mL, when a 20 μL aliquot of urine was injected directly into (LC-MS-MS) system.Recently, two LC-MS/MS assays were reported for analysis of structurally related compound, tranexamic acid in human plasma with an assay range of 0.8-200 µg/mL [12] and 1-200 µg/mL [13].In the present study, we report a simple and selective LC-MS/MS assay for quantitation of EACA in human plasma in concentration range of 1-250 µg/mL.This assay has been successfully employed for analysis of EACA in pediatric plasma samples [14,15]. | 2 |
29158677 | Reagents and chemicals EACA (epsilon-aminocaproic acid) and 7-aminoheptanoic acid were purchased from Sigma-Aldrich (Cambridge, MA, USA) (Fig. 1).The different lots of drug-free (blank) human plasma (prepared with citrate-phosphate-dextrose, or citrate-phosphate-dextrose-dextrose or citrate-phosphate-dextrose-adenine) were obtained from the blood bank at The Children's Hospital of Philadelphia.HPLC grade methanol and acetonitrile were purchased from Fisher-Scientific (Pittsburgh, PA, USA) and reagent-grade formic acid (~96%) was purchased from Sigma-Aldrich Co. (St.Louis, MO, USA).Deionized water was prepared using a Barnstead Nanopure™ water purifying system from Thermo Fisher Scientific (Marietta, OH, USA). | 3 |
29158677 | Liquid chromatography The Shimadzu HPLC system consisted of two LC-20AD delivery pumps, a DGU-20A5 Shimadzu vacuum degasser, a SIL-20AC Shimadzu autosampler and a CBM-20A system controller (Shimadzu Scientific Instruments; Columbia, MD, USA).HPLC separations were performed on a Thermo Scientific Nucleosil C18 analytical column (3 x 100 mm, 3.5 µm 120 A).For chromatographic separation, water with 0.1% formic acid was used as mobile phase A and methanol was used as mobile phase B. The linear gradient was as follows: 0.00-0.50minutes mobile phase A 80%, mobile phase B 20%; 0.51-3.00minutes mobile phase A 20%, mobile phase B 80% with divert valve off; 3.00-3.51minutes mobile phase A 80%, mobile phase B 20%; and initial gradient maintained until 6 minutes.The flow rate was 0.50 mL/min and 5 µL of the sample was injected for each analysis.The column and autosampler were maintained at room temperature and 10°C, respectively.An electronic valve actuator with a Rheodyne selector valve was used to divert LC flow to waste, at the first 0.5 minute and the last 3 minutes, when no data acquisition was taking place. | 4 |
29158677 | Mass spectrometry analysis Samples were analyzed with an ABI/Sciex 4000 triple quadropole mass spectrometer equipped with Turbo Ionspray.Software for controlling this equipment, acquiring and processing data was Analyst version 1.6.2software (MDS Sciex; Toronto, Canada).The positive ion mode for MS/MS analysis was selected.Nitrogen (purity >99.999 %) was used as the nebulizer, auxillary, collision and curtain gases.Analytes were detected by tandem mass spectrometry using multiple reaction monitoring (MRM) with a dwell time of 100 ms.For the determination of the mass of the precursor and product ions a solution of 500 µg/mL EACA or internal standard in mobile phase (1:1 methanol: water (v/v) with 0.05% formic acid) was infused directly into the ion sources with a Harvard Apparatus syringe pump at a flow rate of 10 µL/min.The most intense precursor-to-fragment transitions using positive turbo spray were: EACA m/z 132.20→79.10;7-aminoheptanoic acid (internal standard) m/z 146.20→55.10.We have used additional MRMs of 132 to 114, 132 to 69 and 132 to 55 to confirm EACA.Product ion spectrum of EACA and 7-aminoheptanoic acid is shown in Fig. 2. The conditions for ionization of EACA and internal standard were optimized using individual standard solutions, each at 500 ng/mL in 1:1 methanol: water (v/v) with 0.05% formic acid at 10 µL/min.EACA and internal standard were infused by a syringe pump alone or through a Tee device at a flow rate of 10 µL/min into the stream of mobile phase (1:1 methanol: water (v/v) with 0.05% formic acid at 0.5 mL/min).eluting from the LC column through a mixing Tee and then into the turbo spray source, to mimic the LC-MS/MS conditions.The main working parameters of the mass spectrometer were: collision activate dissociation (CAD) gas, 8; curtain gas 40; Gas 1 (nebulizer gas) 80; Gas 2 (heater gas) 50; source temperature 600°C.The optimized declustering potential (DP), entrance potential (EP), collision energy (CE), collision cell exit potential (CXP) were set at 46, 10, 23, 6 for EACA; 46, 10, 50, 10 for 7-aminoheptanoic acid (IS). | 5 |
29158677 | Preparation of standards and quality control (QC) samples Two independent EACA stock solutions at 25 mg/mL in water were prepared: standard solutions were prepared from one stock solution and QC samples were prepared from the other.The stock solutions were stored at -20 °C and were stable at least for 1 year.The primary stock solution was diluted in human plasma to prepare intermediate stock solutions of 500 µg/mL.Working solutions of EACA were freshly prepared by appropriately diluting the respective stock solutions with plasma.Eight standards containing EACA concentrations of 1, 2.5, 5, 10, 25, 50, 100 and 250 µg/mL were prepared by adding the appropriate volumes of working solution into 1.5 mL eppendorf tubes containing plasma.Four QC concentrations were prepared in the same manner by adding appropriate volumes of working solution to obtain concentrations of 1, 4, 40 and 200 µg/mL, representing LLOQ, low, medium and high QCs.The internal standard stock solution was prepared by dissolving 4 mg of 7-aminoheptanoic acid in water to a final concentration of 1 mg/ mL.Internal standard working solution was prepared by diluting the internal standard stock solution with water into a single working solution with a final concentration of 2 µg/mL.Amber glass vials for storing stock solution were used.Representative pharmacokinetic plasma samples used in this study were collected and processed as described previously [15]. | 6 |
29158677 | Sample preparation Blood samples were collected in Microtainer tubes (BD, Franklin Lakes, NJ, USA) containing lithium heparin and stored at 4°C for up to 12 h prior to centrifugation and separation of plasma [14].To 50 µL of each standard, QC, blank, and unknown plasma samples from clinical studies in 1.5 mL Eppendorf tube, 1 mL of 10% acetic acid in water was added (1:20 dilution).Samples were vortex mixed and 50 µL of the aliquot was transferred into a disposable culture tube.To each tube, internal standard solution (50 µL) and 5 mL of water was added and vortex mixed (1:102 dilution).The sample preparation involves net dilution of 1:2040.An aliquot (300 µL) of the final solution was transferred into the appropriate position of a 96 well MicroLiter® plate for analysis.Five µL of the supernatant was injected into the LC-MS/MS system for analysis. | 7 |
29158677 | Method validation Method validation and documentation were performed according to guidelines set by the United States Food and Drug Administration (FDA) for bioanalytical method validation [16].This method was validated in terms of linearity, specificity, lower limit of quantitation (LLOQ), recovery, intra-and inter-day accuracy and precision, and stability of the analyte during sample storage and processing procedures [17].Each analytical run included a double blank sample (without internal standard), a blank sample (with internal standard), eight standard concentrations for calibration, and six sets of QC samples: LLOQ QC at 1 µg/mL, low QC at 4 µg/mL, medium QC at 40 µg/mL, and high QC at 200 µg/mL. | 8 |
29158677 | Linearity and sensitivity For the evaluation of the linearity of the standard calibration curve, the analyses of EACA in plasma samples were performed on three independent days using fresh preparations.The calibrations curves were prepared over a linear range of 1-250 µg/mL at eight concentrations of 1, 2.5, 5, 10, 50, 25, 50, 100, and 250 µg/mL.Each calibration curves consisted of a double blank sample, a blank sample, a plasma blank sample and eight calibrator concentrations.Another double blank sample was analyzed immediately following the highest concentration standard in each run to monitor for carryover of EACA or the internal standard.The calibration curve was developed using the following criteria: (1) the mean value should be within ±15% of the theoretical value, except at the LLOQ, where it should not deviate by more than ±20%; (2) the precision around the mean value should not exceed a 15% coefficient of variation (CV), except for LLOQ, where it should not exceed a 20% CV. (3) at least 75% of the eight non-zero standards of each nominal concentration should meet the above criteria; (4) the linear correlation coefficient (r, Pearson product moment correlation coefficient) should be greater than or equal to 0.98.Each calibration curve was constructed by plotting the EACA to internal standard peak area ratio (y) against the EACA concentrations (x).The calibration curves were fitted using a least-square linear regression model y=ax+b, weighted by 1/x 2 using the Analyst ® software.The resulting a, and b parameters were used to determine back-calculated concentrations, which were then statistically evaluated. | 9 |
29158677 | Specificity The specificity was defined as non-interference at retention times of EACA from the endogenous plasma components and no cross-interference between EACA and internal standard using the proposed extraction procedure and LC-MS/MS conditions.Six different lots of blank (EACA free plasma, prepared with lithium heparin as a anticoagulant) were evaluated with and without internal standard at low QC concentration (4 µg/mL) to assess the specificity of the method. | 10 |
29158677 | Accuracy and precision The intra-and inter-assay precisions were determined using the CV (%), and the intra-and inter-assay accuracies were expressed as the percent difference between the measured concentration and the nominal concentration.The % accuracy of the method was expressed by the formula: %accuracy=(measured concentration)/(nominal concentration) x 100%.Intra-assay precision and accuracy were calculated using replicate (n=6) determinations for each concentration of the spiked plasma sample during a single analytical run.Inter-assay precision and accuracy were calculated using replicate (n=6) determination of each concentration made on three separate days. | 11 |
29158677 | Recovery (extraction efficiency) and matrix effect The extraction efficiency of EACA was determined by analyzing three replicates of EACA plasma samples at three QC concentrations of 4, 40 and 200 µg/mL.Recovery was calculated by comparing the peak areas of EACA added into blank plasma and extracted using the protein precipitation procedure with those obtained from EACA spiked directly into post-protein precipitation solvent at the four QC concentrations.The matrix effect was measured by comparing the peak response of the post-extracted spiked sample with those of the pure standards containing equivalent amounts of the EACA prepared in mobile phases.In addition, post-column infusion method described by Bongfiglio et al. [18] was employed to test matrix effect in six lots of blank plasma. | 12 |
29158677 | Stability study The stability of EACA in human plasma was assessed by analyzing replicates QC samples at concentrations of 4, 40 and 200 µg/mL (n=6), during the sample and storage procedure (in 4 mL amber vials).For all stability studies, freshly prepared and stability testing QC samples were evaluated by using a freshly prepared standard curve for the measurement.The short term stability was assessed after exposure of the plasma samples to room temperature for 24 hours (n=6).The long term stability was assessed after storage of the plasma samples -80°C for up to one year (n=6).The freeze/thaw stability was determined after three freeze/thaw cycles (room temperature to -80°C, n=6).The concentrations obtained from all stability studies were compared to freshly prepared QC samples (n=6), and the percentage concentration deviation was calculated.The analyte was considered stable in human plasma when the concentration difference was less than 15% between the freshly prepared samples and the stability testing samples. | 13 |
29158677 | Pharmacokinetics of EACA in children This assay was implemented for analysis of PK samples from healthy infants aged 2-24 months undergoing craniofacial surgery without history of renal impairment or a history of a coagulation disorder [15].Subjects were sequentially enrolled in one of the three cohorts.Each subject received an intravenous (IV) loading dose (25 or 50 or 100 mg/kg) of EACA followed by a continuous IV infusion (CIVI) of EACA (10 or 20 or 40 mg/kg/h) as described previously [15].PK samples, consisting of 1 ml of blood, were drawn (in lithium heparin tubes) immedi-from 96.9-102% (Table 1).Validation results for the replicates of quality control samples are depicted in Table 2.The intraday precision (n=6) ranged from 4.71-10.4% with the accuracy ranging from 92.3-106%.The inter-day (n=18, 3 days) precision ranged from 4.68-9.79%with the accuracy ranging from 95.4-103%.These data con-ately before and after the loading dose, after initiation of CIVI (0.5, 2, 4-6 h), at the end of the CIVI, and after the end of the CIVI (0.5, 3, 6, 9, 12, and 15 h), for a maximum total of 12 PK samples [15].Plasma was separated by centrifugation and stored at -80ºC until analysis. | 14 |
29158677 | Linearity, sensitivity and specificity The method was validated at the above criteria and found to be linear for the concentration range of 1 -250 µg/ mL.A representative calibration curve for EACA is shown in Fig. 3.The linear correlation coefficient (r) from inter-day analysis was found to be greater than 0.98 in all cases.The LLOQ was 1 µg/mL, demonstrating a %CV less than 10% (precision) and accuracy greater than 92%, with a signal-to-noise (S/N) ratio of greater than 10.LLOQ was determined as the concentration at which all acceptable criteria are met and the measured concentration was within ±20% of the nominal concentration.The limit of detection (LOD) was 0.25 µg/mL, which was determined by the lowest concentration with acceptable chromatography, the presence of precursor and product ions with a relative retention time within ±2% of average retention time of EACA, an accuracy of within ±20% and a S/N ratio of at least 3 [11].A representative chromatogram of double blank, LLOQ, internal standard and a clinical plasma sample are shown in Fig. 4. Analysis of six different blank plasma samples and the corresponding spiked low QC (4 µg/mL) showed no significant interference from endogenous compounds (data not shown).No carryover of peaks was observed at the retention time or ion channels of EACA or IS. | 15 |
29158677 | Precision and Accuracy At the eight calibration standards, the intra-day (n=6) precision ranged from 1.1-7.1% and the accuracy ranged measured concentrations of EACA (mean ± SD, n=6) in the post-extract spiked samples were 4.11 ± 0.16, 39.5 ± 1.69 and 180 ± 2.23 µg/mL, respectively.To further evaluate matrix effect, blank extracts from 6 lots of human plasma were analyzed by post-column infusion method described by Bongfiglio et.al. [18].No significant ion suppression was seen at the retention time of EACA in the infusion chromatograms (Fig. 5), confirming that there was minimal or no matrix effect observed for EACA after 1: 2040 plasma dilution and the HPLC separation. | 16 |
29158677 | EACA stability The stability of EACA was investigated to cover expected conditions during sample preparation and storage for all samples, which include data from freeze/thaw, shortterm and long-term stability studies (Table 3).The precision for freeze/thaw samples (n=6) ranged from 1.4-10.9%and the accuracy ranged from 92.1-105%.The results indicated that the analyte was stable in plasma for three cycles when stored at -80 °C and thawed to room temperature.The precision for 24 hour bench-top stability (n=6) ranged from 5 -11.3% and the accuracy ranged from 86.4-111%.After 1 year storage at -80°C (n=6), the precision for the quality control samples ranged from 2.6 -8.44% and the accuracy ranged from 93.3-99.7%.These results indicated reliable stability under the experimental conditions of the analytical runs and storage conditions. firm that the present method has an acceptable accuracy, precision and reproducibility for the quantification of EACA throughout the desired concentration range. | 17 |
29158677 | Assay specificity and ionization suppression (matrix effect) Matrix effect can affect the reproducibility from the analyte or the internal standard of the assay.The matrix effect, or intensity of ion suppression or enhancement is caused by co-eluting matrix components.The matrix effect of EACA and IS were calculated using the following formula: % matrix effect = (A/B) x 100%.A represents the corresponding peak areas of the analytes in spiked plasma post-precipitation and B represents peak responses of the pure standards prepared in mobile phases.A value of >100% indicated ionization enhancement, and a value of <100% indicated ionization suppression.The matrix effect was tested on the three QC concentrations (n=6) and six individual lots of blank plasma were evaluated.At 4, 40 and 200 µg/mL QC concentrations the MOORTHY GS J. APPL.BIOANAL | 18 |
29158677 | Pharmacokinetics of EACA in children The representative PK profiles of EACA in 3 subjects are shown in Fig. 6.Subject 1 received an IV loading dose of 25 mg/kg followed by a CIVI of 10 mg/kg/h of EACA (cohort 1), subject 2 received an IV loading dose of 50 mg/kg followed by a CIVI of 20 mg/kg/h of EACA (cohort 2) and subject 3 received an IV loading dose of 100 mg/kg followed by a CIVI of 40 mg/ kg/h of EACA (cohort 3) as described previously [15].The results show that the assay range was appropriate for analysis of EACA in pediatric plasma samples from the clinical trials [14,15].Time (min) EACA Concentration (µg/mL) Figure 6.Semi-logarithmic concentration-time plots of EACA for three subjects.Subject 1: intravenous loading dose of 25 mg/kg followed by a CIVI of 10 mg/kg/ h.Subject 2: loading dose of 50 mg/ kg followed by a CIVI of 20 mg/kg/ h.Subject 3: loading dose of 100 mg/kg followed by a CIVI of 40 mg/kg/ h. | 19 |
29158677 | Discussion EACA is a potent antifibrinolytic agent that inhibits plasmin-plasminogen system [5].EACA is a natural product that is present in wine lees [19] and cyclized product of EACA, caprolactam is used as an intermediate in synthesis of nylon 6 [20,21].We developed an EACA assay that has a rapid sample preparation (1:2040 dilution min-plasminogen system [5].EACA is a natural product that is present in wine lees [19] and cyclized product of EACA, caprolactam is used as an intermediate in synthesis of nylon 6 [20,21].We developed an EACA assay that has a rapid sample preparation (1:2040 dilutionof plasma samples) and a selective LC-MS/MS method capable of analyzing small volumes of plasma samples, which is ideal for use in pediatric clinical trials [14,15].The LC-MS/MS assay reported here accurately and precisely quantitates EACA concentration in 50 µL plasma specimens with a limit of quantification of 1 µg/mL.The intra-day and inter-day coefficients of variation were less than 10.4% at all concentrations tested.Assay range of 1-250 µg/mL is well suited for expected concentration ranges in pediatric pharmacokinetic studies.EACA had good recovery and stability under assay conditions.Our stability data is consistent with the reported results that EACA was stable at 20ºC for 3 months [22].At higher temperature (50 -80ºC), EACA degrades to form small amounts of dimer, trimer and caprolactam.However, in urine samples EACA was reported to be stable only for 3 days at 4ºC [11].There was no significant carryover or matrix effect observed for EACA with six different lots of blank plasma in post-column infusion studies.However, there was a significant matrix effect observed with urine samples for EACA analysis and the issue was resolved by diluting and analyzing urine samples [11].This is consistent with our finding that there was no significant matrix effect from 1:2040 diluted plasma samples.We were able to take advantage of the selectivity and sensitivity of LC-MS/ MS and high concentrations of EACA expected in clinical samples and develop a simple and reliable assay for the determination of EACA in human plasma.The minimum effective concentration of EACA to control systemic fibrinolytic activity was determined to be 130 µg/mL [23][24][25].Various dosing strategies based on PK studies in adults [26,27] and children [28] have been targeted to maintain plasma EACA levels at or above this therapeutic concentration.Previous pharmacokinetic studies of EACA have shown that renal excretion was the major route of elimination, whether administered orally or IV [29][30][31][32][33]. Approximately 65-75% of the dose is eliminated in the urine as unchanged drug while ~11% of the dose excreted as adipic acid [29,30,32,33].EACA pharmacokinetics is influenced by weight, age, and perioperative conditions.Weight-based dosing was suggested based on the modelling, a loading dose of 100 mg/kg followed by a CIVI of 40 mg/kg/h is appropriate to maintain target plasma EACA concentrations in patients 6-24 months of age [15].EACA was well tolerated and no adverse events were attributed to its administration.This assay has been successfully utilized for analysis of EACA in clinical studies [14,15]. | 20 |
238682332 | During a screening for novel and useful actinobacteria in desert animal, a new actinomycete was isolated and designated strain TRM63209T. The strain was isolated from in vivo of a Blattella germanica in Tarim University in Alar City, Xinjiang, north-west China. The strain was found to exhibit an inhibitory effect on biofilm formation by Candida albicans ATCC 18,804. The strain was observed to form abundant aerial mycelium, occasionally twisted and which differentiated into spiral spore chains. Spores of TRM63209T were observed to be oval-shaped, with a smooth surface. Strain TRM63209T was found to grow optimally at 28 °C, pH 8 and in the presence of 1% (w/v) NaCl. The whole-cell sugars of strain TRM63209T were rhamnose ribose, xylose, mannose, galactose and glucose, and the principal polarlipids were found to be diphosphatidylglycerol, phos-phatidylethanolamine, phosphatidylcholine, phosphatidylinositol mannoside, phosphatidylinositol and an unknown phospholipid(L). The diagnostic cell wall amino acid was identified as LL-diaminopimelic acid. The predominant menaquinone was found to be MK-9(H6) (14.64%), MK-9(H2) (19.65%), MK-9(H8) (22.34%), MK-10(H2) (25.37%). The major cellular fatty acids were identified as iso-C16:0, 16:0, anteiso-C15:0, anteiso-C17:0, iso-C15:0 and Sum in Feature 3. Analysis of the 16S rRNA sequence showed that strain TRM63209T exhibits high sequence similarity to Streptomyces bungoensis strain DSM 41781T 98.20%. A multi-locus sequence analysis of five house-keeping genes (atpD, gyrB, rpoB, recA and trpB) and phylogenomic analysis also illustrated that strain TRM63209T should be assigned to the genus Streptomyces. The DNA G + C content of the strain was determined to be 70.2 mol%. Average nucleotide identity (ANI) between strain TRM63209T and S. bungoensis DSM 41781T, Streptomyces phyllanthi PA1-07T, Streptomyces longwoodensis DSM 41677T and Streptomyces caeruleatus NRRL B-24802T were 82.76%, 82.54%, 82.65%, 84.02%, respectively. Digtal DNA-DNA (dDDH) hybridization were 26.30%, 25.10%, 26.20%, 29.50%, respectively. Therefore, it is concluded that strain TRM63209T represents a novel species of the genus Streptomyces, for which the name Streptomyces blattelae is proposed. The type strain is TRM63209T (CCTCC AA 2018093T = LMG 31,403 = TRM63209T). | 1 |
238682332 | Introduction The genus Streptomyces was initially described in 1943 (Waksman and Henrici 1943) and more than 850 species with valid names of Streptomyces have been published (https://www.bacterio.net/streptomyces. html) (Zhang et al. 2017). Streptomyces are aerobic Gram-positive bacteria with well-developed mycelia, which can produce a large number of conidia for reproduction. The members of the genus are with high DNA G ? C content, and species are widely distributed in aquatic and terrestrial ecosystems. Many Streptomyces undergo morphological differentiation and also have a mycelial phase. Streptomyces are highly versatile and produce an abundant array of bioactive secondary metabolites (Genilloud 2017) that have been used as antibiotic, anti-carcinogenic, antihelminthic and antifungal compounds. Consequently, they are very important for biotechnology, medicine and agriculture (Barka et al. 2015). Strain TRM63209 T isolated from in vivo of an Blattella germanica in Tarim University in Alar City, Xinjiang, north-west China(40°55 0 N,81°29 0 E) This strain inhibits the formation biofilm of Candida albicans ATCC 18,804. On the basis of phylogenetic, phenotypic and genetic data, TRM63209 T considered to a novel species of the genus Streptomyces, for which the name Streptomyces blattelae is proposed. | 2 |
238682332 | Isolation of Streptomyces strain and culture conditions As part of a program to unravel the diversity of symbiotic actinomycetes in insect-microbe and to discover novel actinomycetes and novel natural products, strain TRM63209 T was isolated from the in vivo of a Blattella germanica, the Tarim University, Alar, Xinjiang Province, north-west China. Blattella germanica is washed with sterile distilled water to remove surface impurities. The surface was sterilized in 70% ethanol for 60 s and then washed three times in sterile distilled water. Grind it to a powder and suspend in sterile distilled water incubated on a rotary shaker at 180 rpm 37°C for 30 min (Liu et al. 2017), ultrasound 3 min, and the suspension was appropriately diluted before being spread onto Czapek's agar (Wiese et al. 2008) supplemented with nystatin (100 mg/ml) and nalidixic acid (50 mg/ml) (Arocha-Garza et al. 2017). After 21 days of incubation at 28°C, the isolate was transferred and purified on International Streptomyces Project (ISP) 4 medium (Shirling and Gottlieb 1966) and the spore and mycelia maintained as glycerol suspensions (20%, v/v) at -80°C. | 3 |
238682332 | Chemotaxonomy Isomers of diaminopimelic acid were analysed following the method of Hasegawa et al. (1983). The whole cell sugar composition was analysed following the method of Staneck and Roberts (1974). Polar lipids in cells of strain TRM63209 T were extracted and examined by two-dimensional TLC and identified following the methods of Minnikin et al. (1984). Menaquinones were extracted using the method of Collins (1985) and subjected to HPLC analysis (Groth et al. 1997). The cellular fatty acid composition was determined using the Microbial Identification System (MIDI Sherlock version 6.0) (Sasser 1990). | 4 |
238682332 | Phylogenetic analyses Genomic DNA extraction and PCR amplification of the 16S rRNA gene from strain TRM63209 T were performed following Chun and Goodfellow (1995). The purified PCR product was cloned into the vector pMD19-T (Takara) and sent to Sangon for gene sequencing. Multiple alignments with sequences from closely related Streptomyces species and calculations of sequence similarity were performed using the EzTaxon-e server (Kim et al. 2012). Phylogenetic analyses were performed using MEGA version 7.0 (Kumar et al. 2016) selecting the neighbour-joining (Saitou and Nei 1987), Maximum-Evolution (Rzhetsky and Nei 1993) and maximum-likelihood (Felsenstein 1981) algorithms. Topologies of the resultant trees were evaluated using the Felsenstein's (1985) resampling method with 1000 replications. AtpD, gyrB, rpoB, recA and trpB genes were obtained using primers and amplification conditions as previously described (Guo et al. 2008;Hatano et al. 2003). Phylogenetic relationships were reconstructed using the Neighbour-Joining algorithm as described above. Phylogenomic analysis was performed online by Type (strain) Genome Server (TYGS) (Meier-Kolthoff et al. 2019). The whole genome of TRM63209 T was sequenced by Oxford Nanopore technologies. The DNA G ? C content of strain TRM63209 T was obtained by whole genome sequencing. The Average nucleotide identity (ANI) was determined as described by Lee et al. (2015). DNA-DNA relatedness values were determined online according to the method of Meier- Kolthoff et al. (2013). DNA-DNA hybridization (dDDH) values were calculated at the Genome-to Genome Distance Calculator (GGDC) website using formula 2, as originally described by Auch et al. (2010) and updated by Meier-Kolthoff et al. (2013). Anti-SMASH was used to predict the biosynthetic gene clusters of strain TRM63209 T (Blin et al. 2013). Antifungal and antibacterial activity C. albicans ATCC 18,804 was obtained from China Center for Type Culture Collection, and was cultured with Sabouraud dextrose agar/broth (SDA/SDB). Unless specified otherwise, ISP 3 was used to culture TRM63209 T strain. A 4% (v/v) inoculum of well-growing strain TRM63209 T was used to culture strain TRM63209 T in ISP 3 liquid culture medium (20 g oatmeal and 1 ml trace salt per L distilled water) and incubated at 28°C with shaking at 180 rpm for 10 days. Cells were removed by centrifugation to leave the supernatant, which was kept at 4°C for further screening of biofilm inhibition. The effect of the strain TRM63209 T growth supernatants on static biofilm formation measured according to Balasubramanian et al. (2017). Briefly, test organism cells were diluted 1:100 with fresh SDB to bring the test cell suspension to a concentration of 1 9 10 8 cells per mL. 100 lL aliquots of cells were added to the wells of a 96 well plate and 100 lL of supernatants was added, then the plates inoculated with C. albicans were incubated at 37°C for 72 h. Wells without the supernatant (100 lL SDB) was used as blank control. After crystal violet staining, the absorbance was measured at 490 nm by an enzymelinked immunosorbent assay reader (Bio-Rad). Relative activity of biofilm formation was indicated as Relative Biofilm Formation % (RBF %) calculated the following formula: RBF % = Treated OD 490 /Untreated OD 490 9 100%. | 5 |
238682332 | Results and discussion Strain TRM63209 T was observed to grow optimally on ISP 3 and ISP 2, and showed moderate growth on ISP 1, ISP 4, ISP 5, nutrient agar and Gause's synthetic agar no. 1, with slow growth on ISP 6, ISP 1 and Czapek's medium. Light yellow soluble pigment was produced in ISP 5 and greenish White soluble pigment was produced in ISP 6, the colour of other the aerial mycelium is white, other no diffusible pigment was produced on the media test, the color of ISP 2 substrate mycelium is light yellow ( Table 1). The growth and cultural characteristics of strain TRM63209 T related type strains are listed in the species description and in Table S1. Morphological characteristics of strain TRM63209 T were observed using SEM (Fig. 1). The strain was observed to form an abundant white aerial mycelium, occasionally twisted, which differentiates into spiral spore chains. Each spore was observed to be oval-shaped with a smooth surface (Fig. 1). Strain TRM63209 T was found to grow only at 5-55°C, pH 4.0-12.0 and 0-20% (w/v) NaCl, with optimal growth at 28°C, pH 8.0 and with 1% (w/v) NaCl. Other physiological characteristics of strain TRM63209 T are listed in the species description and in Table 1. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain TRM63209 T belongs to the genus Streptomyces, with high sequence similarity to Streptomyces bungoensis DSM 41781 T (GenBank accession no. KQ948892; 98.20%), Streptomyces phyllanthi PA1-07 T (GenBank accession no. LC125632; 98.14%), Streptomyces longwoodensis DSM41677 T (GenBank accession no. KQ948572; Rong and Huang (2012), in multi-locus sequence analysis (MLSA) it is considered that pairs with evolutionary distances greater than 0.007 belong to different species. A MLSA of five house-keeping genes (atpD, gyrB, recA, rpoB, and trpB) indicated that the MLSA distances between strain TRM63209 T and similar species were greater than the 0.007 threshold (Fig. S7). Result of phylogenomic analysis also supported that strain TRM63209 T belonged to genus Streptomyces (supplementary Fig. S8). The DNA G ? C content in the draft genome sequence of strain TRM63209 T was determined to be 70.2 mol %. The complete genome of strain TRM63209 T has a size of 8.49 Mb, did not distribute among chromosomes and plasmids. In its genome, 7804 genes were annotated, of which 7732 are putative protein-coding genes. The number of hypothetical proteins is 2367, corresponding to 31% of the total number of putatively annotated proteins. 60 tRNAs and seven copies of the 16S rRNA gene were identified. The genomic characteristics of the compared strains are quite heterogeneous (Table. S4). The ANI relatedness between strain TRM63209 T and the phylogenetically related strain Streptomyces caeruleatus NRRL B-24802 T , Streptomyces bungoensis DSM 41781 T , Streptomyces longwoodensis DSM 41677 T and Streptomyces phyllanthi PA1-07 T were respectively determined to be 84.02%, 82.76%, 82.65%,82.54%. This value is significantly lower than the widely accepted threshold for describing prokaryote species (95-96%; Kim et al. 2014). The dDDH value between strain TRM63209 T and the phylogenetically related strain Streptomyces bungoensis DSM 41781 T , Streptomyces phyllanthi PA1-07 T , Streptomyces longwoodensis DSM 41677 T and Streptomyces caeruleatus NRRL B-24802 was respectively determined to be 26.30%, 25.10%, 26.20%, 29.50%. significantly lower than the 70% threshold value for delineation of prokaryotic genomic species (Wayne et al. 1987). It is thus proposed that strain TRM63209 T can be differentiated from closely related Streptomyces species and represents a novel species. The supernatant of strain TRM63209 T inhibited biofilm formation by both C. albicans, with inhibition ratios over 40% (Table S3). The anti-SMASH biosynthetic gene cluster prediction tool was used to investigate the draft genome sequence of strain TRM63209 T and found one type I, two type III polyketide biosynthetic gene clusters, five nonribosomal peptide synthetase biosynthetic gene clusters and one NRPS-like fragment. In addition, five terpene, three siderophore, three class i lanthipeptide clusters like nisin, one nonalpha poly-amino acids like e-Polysin (NAPAA), one ectoine, one arylpolyene, one other unspecified ribosomally synthesised and post-translationally modified peptide product (RiPP), one redox-cofactors such as Table 2 Differential characteristics between strain TRM63209 T and phylogenetically related species of the genus Streptomyces Table. S4. A product of one of these clusters may be involved in the antibiofilm activity observed. Through anti-SMASH analysis, the 7-prenylisatin antibiotic biosynthesis gene cluster can be found, which can effectively inhibit the growth of fungi and the similarity to 60%, whereby the strain TRM63209 T inhibits the formation of BF may be associated with this gene cluster (Liang D). In summary, the sequencing of the genome of strain TRM63209 T further clarified the evolutionary relationship between strains and will guide the screening for active secondary metabolites. The type strain, TRM63209 T (CCTCC AA 2018093 T = LMG 31,403), was isolated from the in vivo of a Blattella germanica in Tarim University, Alar City, Xinjiang Province, The GenBank/EMBL/ DDBJ accession numbers for the genome and 16S rRNA gene sequence of strain TRM63209 T are WJBG00000000 and MK795724, respectively. | 6 |
94920295 | Five membered nitrogen and sulfur heterocyclic compounds such as isatins, benzimidazole, benzimidazolin-2-thi one, bcnzoxazoli none- 2, bcnzoxazoli n-2-th ione, henzotriazole, benzoth iazoli n-2 -th ione, 1 ,3,4-oxadiazoli n-5-thione and 1,2,4-triazolin-5-thiones have been prepared and subjected to aminomethylation reactions in pres ence of formaldehyde and amines. Secondary as well as primary aromatic amines bearing different substituents have been successfully utilized in the aminomcthylation reaction. The aminomethylated products have been tested for antibacterial, antifungal, antiviral, anticancer, antileishmanial and antifilarial activity. A number of such products have exhibited promising antifungal and antileishmanial activities. and sulfur five membered heterocyclic com pounds active hydrogen atom to nitrogen | 1 |
94920295 | 4-Chloroisatin 70% pH 4.5 The isomeric mixture 5 of 4 and 6 ch\oro isatins was dissolved in N/2 NaOH. The solution was filtered. To the filtrate N/2 HCl was gradually added. As the pH dropped below 8 precipitation of 4-chloroisatin commenced which was completed at pH 4. 5 be due to extensive sulfonation of the aromatic ring due to strong activating influence of methoxy group. With a view to moderating the electron donating influence of methoxy group to a considerable extent a bromine/chlorine atom has now been introduced at position-3 of panisidine and position-4 of m-anisidine. The 3-bromo/ chloro-4-methoxy and 4-bromo/ch !oro-3-methox y anilines, thus obtained, were converted to the corresponding isonitrosoacetanilides, which underwent smooth cyclization in cone. sulphuric acid furnishing the mixtures of isomeric pairs consisting of 4-bromo/chloro-5methoxy-, 6-bromo/chloro-5-methoxy-and 5-bromo/ chloro-4-methoxy-, 5-bromo/ch loro-6-methoxy-isatins in 80-85% yields. Thus, mild electron withdrawing or mild electron donating groups give isatins in excellent yields and strong electron donating groups have to be suitably moderated in order to obtain better results (Scheme 4). During dissolution of isomeric pairs of 4-and 6-substituted isatins in sodium hydroxide solution, the isatin ring opens up resulting in the formation of the sodium salt of the corresponding isatinic acid which on acidification with HCl immediately cyclizes back to isatin (Scheme 4). The isatinic acid anion corresponding to the 4-substituted isatin is a relatively strong conjugate base, and, therefore, more inclined to accept a proton. It stabilizes at pH 8.0 or above. The lowering of pH value below 8.0 destabilizes the isatinic acid anion resulting in the liberation of isatinic acid which, immediately gets transformed into the 4-substituted isatin. The continuous removal of isatinic acid in the form of 4-substituted isatin prevents the establishment of isatinic acid anion!isatinic acid equilibrium resulting in almost total conversion of isatinic acid anion to the 4-substituted isatin as the pH is progressively brought down to 4.5. The isatinic acid anion corresponding to the 6-substituted isatin is a relatively weak conjugate base and, therefore, less inclined to accept a proton. It continues to remain stable at pH as low as 4.0. The anion gets destabilized when the pH value is lowered below 4.0 leading to the formation of the corresponding isatinic acid which immediately undergoes cyclisation yielding the 6-substituted isatin. The precipitation is complete as the pH is brought down to 2.0. | 2 |
94920295 | ¢' -~ It is obvious that the precipitation of 4-and 6-substituted isatins from alkaline solution of their isomeric mixtures over widely differing pH values affords a novel and efficient method for their separation. The method, indeed is of wide applicability as it can be used to separate iso-meric binary mixtures of organic acids with a marked difference in their relative acidity. This has been experimentally verified by effecting the separation of ochlorobenzoic acid and p-chlorobenzoic acid from the alkaline solution of their mixtures. As expected the pchlorobenzoic acid, being relatively week acid, precipitated out at a higher pH while the o-chlorobenzoic acid separated out at a lower pH value. The substituents at 4/6 position of isatin acquire positions ortho!para to the carbonyl group in the conesponding isatinic acid, respectively. The acidity of isatinic acids is determined to a large extent by the proximity of the carbonyl group to the carboxylic group. The relative acidity of an isatinic acid with a substituent ortho to the carbonyl group is apparently less than its isomer with substituent para to the carbonyl group. This is in contrast to the substituted aromatic acids where the orthosubstituted acids are invariably stronger than their paraisomers. The relative proximity of the substituent ortho to the carbonyl group, greatly reduces ·its inductive effect, thus rendering the isatinic acid relatively week. The substituent para to the carbonyl group, on the other hand, exerts its inductive effect in a normal manner, thereby making the isatinic acid relatively strong. Aminomcthylation of 4-bromo-5-rncthox.yisati 11 and 6-bromo-5mctbox.yisatin 630 isati ns 6 ( 19) thus separated in a pure state were aminomethylated with morpholine in the presence of formalin to yield corresponding !-ami nomethylated products (20,21). It is interesting to note that the is<itin N-Mannich bases appeared to be more promising as antiviral agents. Next a series of 4-arylthiosemicarbazides were prepared and condensed with isatins in acidic medium. The 3-arylthiosemicarbazono-2-indolinones thus prepared were then treated with formalin and secondary amines leading to aminomethylated-2-indolinones (28). A number of benzoyl hydrazines, anilino-acetyl hydrazines and phenoxy acetyl hydrazines were prepared by the standard procedures. These hydrazine derivatives were then condensed with isatins as nucleophilesl4-17. The products obtained after condensation were subjected to a1ninomethylation reactions. The aminomethylated products were obtained in excellent yields (32)(33)(34)41) compound (39) was prepared via a number of steps starting from (35) as indicated in the Scheme 5. | 3 |
94920295 | Aminomethylation of benzimidazole Benzimidazole(s) (48) contain an active hydrogen atom attached to nitrogen which can be easily replaced by an aminomethyl group 18 -22 (49) in the presence of formalin and an amine. Many benzimidazoles arc available commercially. If desired they arc easily prepared from appropriately substituted o-phcnylcnc diamine (47) and formic acid. One can also take acetic acid in place of formic acid to get 2 methylbenzimidazolc. Thus by taking appropriate carboxylic acid one can get appropriately 2-substituted benzimidazoles. 2-Substitutents in benzimidazole bulkier l!CS-2 | 4 |
94920295 | 632 During fusion with urea considerable decomposition takes place resulting in the lower yields of the material. We have developed a preparative method for benzoxazolinone-2. In this procedure o-aminophenol and urea are heated in dry pryridine. After pyridine is distilled off the residue is poured into water thereby pure benzoxazolinone-2 is obtained in high yields 29 . Aminomethylation of benzoxazolinone-2 has been done in ethanolic medium in the presence of formalin and an amine. Different types of amines have been utilized to obtained the required amino methylated products 30 -4 | 7 |
94920295 | Aminomethylation of benzoxazolin-2-thione Next we have taken a closely related system benzoxazolin-2-thione (64) to be studied for amino-methylation reaction. Its method of preparation is described in organic synthesis 41 . The procedure involves treatment of o-aminophenol (63) with potassium ethylxanthate in ethanol followed by acidification of the reaction mixture with acetic acid. The benzoxazolin-2-thione (64) thus obtained has been treated with formalin and amines. The reaction takes place both with secondary as well as with primary aromatic amines 42 -4 4 (69) (Scheme 9). | 8 |
94920295 | Aminomethylation of benzotriazole Benzotriazole, a five membered heterocyclic system with three nitrogen atoms at 1.2,3 positions contains an active hydrogen atom attached to nitrogen atom. It was subjected to aminomethy1ation reaction 45 benzotriazoles (72) can also be obtained by treating l-hydroxymethylbenzotriazole46 (71) with primary aromatic amines, when 1-dimethylaminomethylbenzotriazole (73) was treated with aniline, the dimethylamino group got displaced with aniline (Scheme 10). | 9 |
94920295 | Microwave mediated aminomethylation Microwave mediated synthesis of heterocyclic compounds have attracted more attention of chemists because of shorter reaction time, simple reaction conditions, higher yields and purer products. Many reactions like oxidation, reduction, alkylation, 0-benzylation, hydrazinolysis, esterification, aromatic substitution and decarboxylation proceed smoothly under microwave conditions. Aminomethylation 57 was the further addition to the microwave mediated reactions. | 10 |
94920295 | Mechanism of aminomethylation reaction The aminomethylation reaction 61 -6 7 is believed to tak.-: place in two steps. Initially the amine reacts with formaldehyde to generate an aminomethylol (A). The aminomethylol (A) then reacts with active hydrogen containing substrate [say for instance benzoxazolinone-2 (B)] to furnish amino methylated product (C). Antileishmanial activity against Aminomethylated compounds showing promising antifungal and antileishmanial activity are listed in Tables 1 and 2. I. | 11 |
85505397 | INTRODUCTION The usage of bismuth as a solvent instead of gallium in the liquid phase epitaxy (LPE) of GaAs has been recently reported and associated with a decrease of the carrier concentration and a considerable increase of carrier mobility in the deposited GaAs layers [1,2].It is well known that silicon is a residual impurity which is always present in GaAs deposited by PLE techniques and therefore this may be explained by a high coefficient of bismuth and silicon interaction Si-Bi in the solutions [1].In depositing GaAs from the Bi-solution we have in fact a three component system GaAs-Bi.The phase diagram of GaAs-Bi system in the area of Ga-Bi-GaAs has been experimentally defined by Evgenev and Ganina [3].It is also known that the GaAs compound is the only interphase of a constant composition and that bismuth is an isoelectronic dopant in the analysed system [4].Its segregation coefficient and solubility in GaAs are very low [1,2,3].By depositing the GaAs epitaxial layers from stoichiometrical solution of Ga and As in bismuth, the greatest solubility Bi in GaAs should be obtained. The physical properties of epitaxial layers obtained from Ga-As-Bi solution over a wide range of compositions of liquid phase have not been described in the literature so far.In this paper preliminary assessment of such layers obtained from Ga-As-Bi solutions with different amounts of bismuth are presented. | 2 |
85505397 | EXPERIMENTAL 2.1 Growth of Specimens The epitaxial layers were grown on Cr-doped semi-insulating (100)m oriented GaAs substrates with > 107ff2cm and dislocation density 5.104/cm supplied by the CEMI (a local vendor).The substrates were cut to dimensions 10 x 11.5 mm and cleaned in organic solvents followed by an etch in a H2SO4:HzOz:H20 solution (12:1:1 volume ratio) and finally rinsed in propan-2-ol.Bismuth, qallium and polycrystalline GaAs of 6N purity were used for preparing of solutions.The mass of the initial composition of liquid phase, i.e. mGa + mBi was constant and equal to 2 gm.This corresponded to 3.2 mm (for 0 at.% Ga) height of the melt in the graphite boat. The epitaxial deposition of GaAs layers were performed in horizontal open system quartz reactor, which contained a conventional graphite sliding boat [5] in a Pd purified H2 ambient atmosphere. The growth processes were performed in two different ways: 1.A two phase technique where the melt was saturated by arsenic from polycrystalline GaAs. 2. An equilibrium cooling technique where the melt was saturated with help of a dummy GaAs:Cr substrate which was identical to a proper substrate.(In this case of course the melt would also contain some chromium, which was present in the dummy substrate.) The saturation of the melt or solution was made for 2 hours at 1073 K. 1073 K is also the normal deposition temperature regardless of melt composition.The compositions of the solutions used in this work are presented in Table 1. Following saturation the melt was brought into contact (by moving the slider of the boat) with the substrate.Simultaneously, the program of the linear cooling with the rate, vn 0.25 K/min was initiated.The layer was deposited for 30 min.Growth times of subsequent layers also 30 mins.Taking into account composition of the solutions used, the epitaxial layers obtained were classified into six technological groups.The compositions of the used solutions and the thicknesses of the obtained layers are shown in Table 1. | 3 |
85505397 | Electrical evaluations of the GaAs Epilayers Hall and C-V measurements were used to characterise the GaAs epitaxial layers and results are summarised in Table 2. The measurements were carried out at 300K.The layers of IV to VI groups were not measured. .3 X-Ray Investigations X-Ray diffraction patterns for the epitaxial layers taken from the technological groups presented in Table 1 were obtained.They were identical in spite of differences in the solution compositions used.(i.e.The same as for the monocrystalline GaAs with cry- stallographic orientation (100).)X-ray photographs obtained by the Laue method confirm the monocrystallinity of each layer.The X-ray photographs of the GaAs:Cr substrate and the epitaxial layers deposited on the substrate for the most representative groups I-VI are presented in Figure 1.Additionally, these layers were tested using X-ray microprobe. | 4 |
85505397 | DISCUSSIONS AND CONCLUSIONS The following conclusions can be drawn from the investigations: the epitaxial layers are GaAs monocrystalline with the crystallographic orientation (100) independent of the used solution composition.Bi and Cr were not identified in the investigated layers in the sensitivity range (0.1 at %) of the X-ray microprobe used. These preliminary results suggest that GaAs of good crystallinity and a carrier density as low as 1014cm -3 can be grown by LPE from Ga-As-Bi solutions and that such a process may offer the potential for producing materials for device fabrication. As K [keV] | 6 |
101406833 | The research work is focused on thermal engine structures undergoing isobaric expansion-compression based thermal engines powered by ocean thermal energy. The isobaric expansion-compression based thermal cycles referred to in this paper, differs from the conventional quadrilateral Carnot based thermal cycles in that the conversion of heat to mechanical work is performed assuming a load reaction driven path function, where as heat is being absorbed (isobaric expansion process) and rejected (isobaric compression process), mechanical work is simultaneously performed without the conventional quasi-entropic expansion, contrary to what happens in conventional quadrilateral based Carnot engines. An analysis of the ideal thermal cycle performed by means of an isobaric expansioncompression based cylinder is carried out and results compared with some previously achieved results of conventional technology including that of a Carnot cycle operating under the same ratio of temperatures. Into the range of its inherent low operating temperatures high ideal thermal efficiency is achieved for hydrogen and helium as working fluids. The achieved results associated with a simple and compact machine Original Research Article British Journal of Applied Science & Technology, 4(26): 3840-3855, 2014 3841 envisage the way towards a new generation of ocean thermal energy convertor (OTEC) power plants operating with the isobaric expansion-compression based cylinder. | 1 |
101406833 | INTRODUCTION All the known thermal cycles under use so far are derived from the Carnot engine, which means quadrilateral cycles in which ideally heat is absorbed at constant temperature (top temperature) and work is delivered when temperature decreases from the top temperature to approach the bottom temperature under a quasi entropic transformation. The power cycles that obey to this model are classified in two main groups based on the nature of the working fluid: gas power cycles and vapour power cycle. The difference between the two groups is that in the first case the working fluid is gaseous and does not experience any phase change, while for the second group, there is a liquid-vapour phase change process of the working fluid within the cycle. In Fig.1 a simple classification of heat engines based cycles is depicted. Thermal cycle based on load reaction driven path functions. Isobaric expansion based path functions at constant load, [19] Non Carnot based heat engine (a) (b) Renewable energy conversion techniques contribute on reducing carbon dioxide emissions, global warming, and environmental pollution. The ocean thermal energy conversion (OTEC) procedure uses the temperature difference between the surface warm seawater and the deep cold seawater to drive Rankine cycle based power plants as power source [1][2][3]. OTEC techniques exhibit a very small environment impact. However the low net efficiency of OTEC as consequence of its inherent low difference of operating temperatures restricts the implementation of this technology [4]. Consequently, improving the thermal efficiency of OTEC based power plants has becoming an important objective, for instance by selecting suitable working fluids for use in the Rankine cycles. In [5,6] the major components of an OTEC plant theoretically and experimentally have been studied. In their simulation results, the temperatures of warm and cold seawater were 26ºC and 4ºC, for optimising a 100-MW OTEC system. The authors reported also that R717 was one of the suitable working fluids for a closed Rankine cycle OTEC power plant. Using R717 as the working fluid, the authors of the work referenced as [7] studied theoretically the effects of temperature and flow rate of cold seawater on the net output of an OTEC power plant. They concluded that the network has a maximal output at a specific cold seawater flow rate. In order to enhance thermal efficiency while reducing system costs, the organic Rankine cycle (ORC) is used with working fluids that have a low boiling temperature. In this way, in [8] and [9] suitable working fluids for an ORC have been investigated to convert low-grade heat. The design for an OTEC based ORC with R717 and R134a has been optimised in [10]. Various applications aiming to increase the thermal efficiency of the OTEC system uses solar heat energy [11,12] and the waste heat of nuclear power condenser [13] to increase the temperature of warm seawater contribution on the thermal efficiency enhancement. In [14] an experimental study measured the temperature and pressure before and after each component of a demonstration OTEC system was reported. According to the report, a maximum thermal efficiency of approximately 1.5% was obtained in the OTEC system when R134a was used as the working fluid. They also determined that both the thermal efficiency and the power output of the system increased upon increasing the operating temperature difference, which is the temperature difference between warm and cold seawater. In [15] a regenerative ORC in which R123 was used as working fluid, and reported that the performance of basic ORC system and the regenerative system were 6.15% and 7.98%, respectively, with a 130ºC geothermal heat source has been experimentally investigated. These results showed that the regenerator in the ORC system improved by 1.83% as the power output was 6kW. From the points of view of performance and economy, finding the optimal operating temperature of the heat exchanger is critical for making the heat exchanger as small as possible when using an available temperature difference of only approximately 20ºC. The heat transfer performance in exchangers of the Rankine cycle has been considered widely to evaluate OTEC systems from an economic standpoint. An objective function, which represented the ratio of total heat transfer area to the net power output of the OTEC system, was presented in [16], who analyzed the optimization for a 1-MW OTEC power system operated in a simple closed Rankine cycle with R717 being used as the working fluid. In [17] A Preliminary assessment of OTEC resources has been performed. Calculations indicated a long-term heating of the tropical water column if deep cold seawater were used at flow rates per unit area of the order of the average abyssal upwelling. The author concluded that this phenomenon would correspond to a transient cooling of the tropical mixed layer, and that such predictions should be further evaluated with a three-dimensional model of the oceanic circulation since a one-dimensional representation does not allow any potential adjustment from convective horizontal currents. According to the mentioned study, about 5 TW of steady-state OTEC power may be available at most. This is slightly more than a recent estimate based on conservative standardised OTEC conditions but it remains much smaller than values generally available in the technical literature. However, the present OTEC resource estimates still largely exceed today's worldwide electricity consumption. It is unlikely that a possible lack of sustainability of OTEC resources at very large scales will ever be tested in practice. Taking into consideration the studies carried out in [17], a limited amount of OTEC based power should be installed and exploited in order to assure long time sustainability. The work has been organised into 5 main sections, where section is 2 is devoted to the description of the combined OTEC power plant, section 3 describes the new thermodynamic concepts regarding the thermal cycle options, in section 4 a case study is included in which the performance analysis and discussion of results have been carried out on a feasible structure of the projected plant, and finally in section 5 some relevant conclusions are highlighted. | 2 |
101406833 | DESCRIPTION OF THE OTEC POWER PLANT OPERATING WITH CLOSED ISOBARIC EXPANSION-COMPRESSION BASED TRANSFORMATIONS The core of the proposed OTEC power convertor is the isobaric expansion-compression based cylinders (IECC), which is schematically depicted in Fig. 2. The OTEC-IECC system shown in Fig. 2 uses four operating fluids: -the thermal working fluid (WF) confined into the cooler and heater heat exchangers and the cylinder, -the cooling working fluid consisting of cool deep seawater necessary to cool the WF acting as heat rejection device which transfers heat from cylinder to the environment, and -the heating working fluid pumped from the hot seawater surface by means of the HSW necessary to heat the WF, and -the hydraulic fluid responsible for transferring hydraulic energy to the hydraulic motor-generation set. The proposed OTEC-IECC depicted schematically in Fig. 2, is composed of the following components: actuator cylinder, coolers, heaters, I/O cooler valves, I/O heater valves, regenerator valve, hot sea water pump, cold sea water pump, reciprocating hydraulic pump equipped with inlet and outlet three way-two position valves, and a hydraulic motorgenerator set. | 3 |
101406833 | Description of the IECC Functioning The IECC is an active part of the OTEC responsible for converting the thermal energy of a gaseous working fluid into mechanical work. According to the structure of the IECC, two general modes of converting thermal energy to mechanical work are feasible: -Conversion of thermal energy to mechanical work by cooling a gaseous working fluid and, -Conversion of thermal energy to mechanical work by heating a gaseous working fluid. | 4 |
101406833 | Fig. 2. Structure of the OTEC implemented with an actuator cylinder as power power convertor The processes of cooling and heating a working fluid, which are responsible for converting heat into work (performing mechanical work), are depicted in Fig. 3. The process of converting partially the thermal energy contained into a gaseous working fluid to mechanical work can be carried out by rejecting heat to the environment for which the condition that the cooling environment temperature is colder than the temperature of the working fluid must be met. To show such paradigm, a double effect cylinder equipped with two coolers and two heaters is depicted in Fig. 3(a). The closed thermodynamic transformations carried out during the cooling process of the cylinder chamber X is referred to the T-s diagram shown in the Fig. 3(b), where the state changes (4)-(5)-(6)-(1) are performed while cooling the cylinder chamber X. In the same way, the process of converting partially the thermal energy contained into a gaseous working fluid to mechanical work can be carried out by absorbing heat from a heat source for which the condition that the heating environment temperature is hotter than the temperature of the working fluid must be met. Thus, the closed thermodynamic transformation carried out during the heating process of the cylinder chamber X is referred to | 5 |
101406833 | Performing mechanical work by cooling a fluid Considering the piston located at position Y and the two position three way valves positioned so that cooler X and heater Y are active, with the rest of heat exchangers inactive, the energy balance for the cooling transformation yields ) ( has been assumed. Therefore the mechanical work delivered during the cooling process is defined as From equations (1) and (2) follows that mechanical work is being developed by rejecting heat as qo. | 6 |
101406833 | Performing mechanical work by heating a fluid Considering the piston located at position X and the two position three way valves positioned so that the heater X and the cooler Y are active, with the rest of heat exchangers inactive, the energy balance for the heating transformation yields has been assumed. As consequence, the mechanical work delivered while heating process is defined as From equations (3) and (4) follows that mechanical work is being developed by absorbing heat as q i . | 7 |
101406833 | Description of the OTEC Thermal Cycle The structure of the thermal cycle composed by IECCs (isobaric expansion-compression based cylinders) which exhibits certain similarity with the plant structure described in [18] is shown in Fig. 2 and Fig. 4 respectively. The cycle functioning consists of four main operating steps described according to the plant structure depicted in Fig. 4 (a) and the T-s diagram of the Fig. 4 (b). The status of the valves is described in Table 1 for non regenerative and regenerative cycles. | 8 |
101406833 | Non-regenerative IECC The non regenerative cycle is composed by the following steps according to the information depicted in Fig. 4(a) and Fig. 4(b): where hot WF expands at constant pressure p 3 =p 2 into the side (X) of the cylinder coming through the valve (HV) at high temperature, and simultaneously, cooled WF is being compressed at constant pressure p 4 = p 1 into the side (Y), leaving the cylinder through the valve (CV) at low temperature. -step (3)-(4)-(1)-(2) where hot WF expands at constant pressure p 2 = p 3 into the cylinder through the valve (HV), and simultaneously cooled WF is being compressed at constant pressure p 4 = p 1 into the side (X) leaving the cylinder through the valve (CV), completing a cycle. | 9 |
101406833 | Regenerative IECC The regenerative IECC is composed by the following steps according to the information depicted with Fig. 4(a) and Fig. 4(c): -step (6)-(1) corresponding to the regeneration phase, where the regeneration valve (RV) remains open and the pressure in the side (X) of the cylinder increases from p 6 to p 1 =p 4 and in the side (Y) decreases from p 3 to p 4 = p 1 , so that the pressure in both sides is equal p 4 = p 1 . -step (1)-(2)-(3) where hot WF expands at constant pressure p 3 =p 2 into the side (X) of the cylinder coming through the valve (HV) at high temperature, and simultaneously, cooled WF is being compressed at constant pressure p 5 = p 6 into the side (Y) at low temperature. -step (4)-(5)-(6) where hot WF expands at constant pressure p 2 = p 3 into the cylinder , and simultaneously cooled WF is being compressed at constant pressure p 5 = p 6 into the side (X), completing a cycle. | 10 |
101406833 | MODELLING THE CLOSED TRANSFORMATION BASED NON REGENERATIVE IECC This section introduces a class of thermal engines characterised by its ability to develop mechanical work simultaneously during the heat absorbing and heat rejection processes. In order to show the behaviour of a generic IECC to which the Carnot statement does not apply, the case of a double acting cylinder designed to develop mechanical work under a constant load-based path function (isobaric path function at constant load) along its active strokes is described. | 11 |
101406833 | The Non Regenerative IECC In order to apply a technique on closed system based transformations in which the cooling phase (4)-(1) responsible for heat rejection is carried out by performing simultaneously useful mechanical work, the thermal cycle depicted in Fig. 4(a) and 4(b) is analysed under ideal assumptions [19]. The supplied heat from an external power source is ( 2 3 2 2 3 2 3 2 3 2 2 3 23 32 The rejected heat to the heat sink is ) )( The specific work is then given as Thus the ideal thermal efficiency is Taking into account that the term ) ( (8) is almost the unity, in practical applications follows that equation (8) (9) which means that the cycle temperatures has very little influence on the ideal thermal efficiency. | 12 |
101406833 | THE NON-REGENERATIVE CASE STUDY Cycle modelling is carried out with data extracted from [20] (REFPROP) and the tool Engineering Equation Solver (EES). The REFPROP consists of an up-to date data base used for property calculations and is available in commercial software packages whose library makes use of Helmholtz fundamental equation correlations to determine fluid properties from the highest-accuracy published data available in literature. Furthermore, the database can be linked with software based tools such Visual Basic, Fortran, C, and even spread sheets to help the automation of data processing. In the proposed case study the data necessary to carry out the performance analysis is presented in Tables A1 and A2 shown in appendix A. For the analysis of the cycle with hydrogen and helium as working fluids, several tests have been carried out to study it's the cycle performance and behaviour into a range of top temperatures of (294-300 K). | 13 |
101406833 | Results and Discussion The results of the study achieved using the EES yield the values of Table 2 and Fig. 5 using the data shown in Table A1 of the appendix A. The data used in the case study for the study of the hydrogen and helium as working fluids is taken from reference [20]. Cycle computation is referred to the T-s diagram of Fig. 4(a) and 4(b) for the non regenerative IECC. The values of the state variables corresponding to each cycle state point for the two working fluids are shown in appendix A, where for every working fluid a range of top temperatures from 294K to 300K has been considered. The seawater temperatures are assumed into a range of 279 K for the cold seawater near to the seabed and 293-299 K for the warm seawater at the sea surface. According to the results shown in Table 2, as the top temperatures increases from 294 K to 300 K it is observed that the thermal efficiencies remain almost constant approaching 58.5% for hydrogen and 80.5% for helium. | 14 |
101406833 | =280 K and T 3 = 298 K It is observed also that while the ideal thermal efficiency exhibits almost no temperature dependence, specific work depends strongly on temperature according to the results shown in Table 2. However, the pressure ratio (defined as the ratio of the highest (top) pressure to the lowest (bottom) pressure into the cylinder) exerts a strong influence on the specific work as depicted in Fig. 5. Consequently, the specific work depends on the top temperature and pressure ratio. From the commented premises follows that high operating pressure with low pressure ratios yield good performance on the basis of a low specific volume, which means low structural masses and sizes while keeping high constant thermal efficiencies. Restrictions on the thermal efficiency imposed by the Carnot factor cannot be applied to the IECC because of its very low dependence on the operating temperatures. As consequence of the analysis of the achieved results shown in Table 2 regarding the Carnot factor, follows that it isn't comparable to the results rendered by the IECC based OTEC because of the inherent differences of the proposed cycle. However the OTEC power plant investigated in [18] will be taken as reference to compare performance results. Thus, in [18] (10) Assuming the losses for the IECC based OTEC similar to the losses of the OTEC described in [18], because of its structural similarities with respect to its heat exchangers, the overall efficiency for a non regenerative IECC can be estimated as Therefore, the net IECC thermal efficiency has been computed for the same top temperatures assumed for the Table 1, which are within the range of 294 K and 300 K. As noted from Table 3, net efficiencies are yet substantially higher than both, the Carnot factor and the CAPILI engine studied in [18]. With the aim of scaling up the proposed model, the results achieved as consequence of the studied case have been extrapolated to a 10 MW OTEC. Thus, using hydrogen and helium as working fluids and using the results depicted in the Table A2 of the appendix A, the main operating parameters for the 10 MW OTEC are shown in Table 4. In this way, Table 4 shows the amount of required working fluid (WF mass kg), the volume at 11 bar (WF vol. m 3 ), including the volume of the heat exchangers located into the cylinder, the total heat flow (heat flow kJ/s), and the total seawater flow (seawater flow kg/s), which includes the cold seawater and the warm seawater. | 15 |
238085136 | Background: This study assessed the effects of varying concentrations of silicon (Si) on the reduction of cadmium (2mg/kg Cd) toxicity in Zingiber officinale Rosc. via growth modulation, photosynthetic efficiency, and antioxidant defense. Result: As the Cd level increased, the physiological indexes of ginger exhibited a decreasing trend. This trend was especially noticeable when the Cd level was 2mg/kg. Next, the effect of different content of soil conditioner Si on ginger under 2mg/kg Cd soil background was explored. This effect was assessed under 2mg/kg Cd soil background. The three treatment Si0 (0), Si1 (1g/kg), Si2 (2g/kg) were examined. Morphology indexes, Cd content, Cd transfer and absorption coefficient, photosynthesis, and antioxidant enzyme activities under Cd stress were determined. On day 120 of the experiment, plant height had increased by 18.8% and 24.7% under the Si1 and Si2 treatments compared with the CK treatment. Meanwhile, the fresh weight of the rhizomes in Si1 and Si2 had increased by 14.3% and 19.5% in comparison with the Si0 treatment. Also, the yield of ginger improved dramatically under the Si1 and Si2 treatments. These treatments had increased by 14.3% and 19.5% compared with the CK treatment. The growth of ginger increased after the addition of Si under Cd stress, especially under the Si2 treatment. The Cd content of the mother-ginger, son-ginger, and grandson-ginger decreased by 27.6%, 35.5%, and 51.2%, respectively, under 2mg/kg Cd stress in the Si2 treatment. The Cd transfer was inhibited from the underground to the aboveground in the high-concentration Si treatment (Si2). When 1 g/kg and 2 g/kg Si was added to the soil, the leaf photosynthetic rate increased by 15.1% and 26.9% compared with the CK treatment at 11:00, respectively. Conclusion : Above all, soil conditioner Si could alleviate the negative effects of Cd stress on ginger by improving growth parameters, photosynthetic efficiency and the antioxidative defense. Si2 (2g/kg) oxide contributes to cadmium toxicity cadmium up-20 | 1 |
238085136 | 3 Background Cadmium (Cd) is one of the most poisonous heavy metals and widespread environmental pollutants [1]. The concentration of Cd in soil has been increasing in recent years. It is ranked as number seven among the top 20 toxins [2]. Its absorption coefficient is higher compared with other heavy metals such as copper and zinc. Absorption of Cd relies on the Cd concentration in soil [3]. As a result of industrial wastewater, exhaust emissions, and inappropriate use of pesticides and fertilizers, Cd pollution in the soil has become increasingly common. It thus poses a serious health risk to humans. Cd can immobilize in soil by binding to organic matter, and it is easily taken up and accumulated by plants [4]. Thus, dietary intake of the biotoxic crops could be a severe threat to humans, and the most likely risk is chronic toxicity in humans [5]. Besides being carcinogenic, Cd inhalations could harm the lungs, liver, kidneys, and bones [6]. In taller plants, Cd could accumulate in any part of the plant since it is highly mobile in phloem tissue. Cd toxicity changes chloroplast ultrastructure, decreases the net photosynthetic rate, leaf transpiration, and stomatal conductance [7]. Cd toxicity is usually accompanied by oxidative stress and DNA breakdown [8] and, ultimately, causes cellular damage or apoptosis [9, 10]. Recent studies indicate that a variety of strategies have been developed to lessen the toxic effects of Cd pollution. Nitric oxide (NO), as a signaling molecule, has a pivotal role in plant resistance to various stresses, including heavy metal stresses, such as Cd [11]. NO could interact with ROS, especially O 2− , because of the presence of an unpaired ewithin the NO molecule [12]. NO improved tolerance to Cd toxicity by reducing oxidative stress that is considered as the leading cause of cell death [13]. In Lupinus, when roots were grown in 50 µM Cd, NO could stimulate SOD activity to counteract the overproduction 4 of O 2− [ 14]. One study found that salicylic acid alleviates Cd-induced photosynthetic damage and cell death by inhibiting reactive oxygen overproduction [15]. The improvement of signal transduction also increased plant tolerance to Cd, and decreased cell death resulted from Cd [10,16]. The soil amendment, Biochar, has been known to protect plants against heavy metal stress [17]. In wheat, Biochar reduced cadmium toxicity for plants growing in Cd-contaminated saline soil [18].Biochar application decreased the oxidative stress in plants and recovered the antioxidant enzyme activities. Silicon is the second-most abundant element in the world, and it could promote plant growth and weaken both biological and non-biological stresses [19,20]. It has been reported that Si plays a vital role in the transfer and accumulation of Cd in plants [21]. Si alleviates Cd toxicity in several ways. It activates the antioxidant system in plants [22], forms Si and Cd precipitants, and restrains Cd translocation, which weakens its biological activity [23]. In rice, 120 mg L − 1 Si decreased Cd accumulation and also reduced the ratio of Cd, transferring from roots to shoots, which lessened the Cd toxicity [24]. In Pisum sativum L, the application of Si decreased Cd accumulation and increased the absorption of macronutrients and micronutrients in shoots and roots, which alleviated Cd toxicity | 2 |
238085136 | Result The effect of cadmium stress on the growth and quality of ginger There is an impact on ginger growth when 1, 2, and 4 mg/kg of Cd are applied during the growth process of ginger (Table 1). At 40d, the plant height and fresh weight were significantly lower than the CK at four mg/kg Cd level. At 80d and 120d after the treatment, the physiological indexes of ginger decreased as Cd levels increased. Above all, the physiological indexes under 2 mg/kg and 4 mg/kg of Cd stress were significantly lower than those of the CK. This indicates that the root growth was significantly inhibited, the number of branches was reduced, and the biomass of the above-ground parts was reduced when the Cd level was higher than 2 mg/kg ( Table 1). The quality indexes of ginger rhizomes indicated there were significant differences among the treatments. The yield and dry weight of ginger showed a decreasing trend with the increasing of Cd levels. The yield decreased by 9.1%, and dry weight decreased by 7.8% 6 compared with the CK at 2 mg/kg of Cd. Gingerols act as the primary indicators when evaluating ginger flavor and quality. As seen in Table 2, the content of gingerols significantly decreased as the Cd level increased. The content of gingerols was reduced by 12.1%, 31.0%, and 38.0% compared with the CK. This showed that the ginger quality was significantly reduced at 2 mg/kg Cd stress ( Table 2). The effect of silicon on the growth and quality of ginger under Cd stress Based on the effect of Cd stress on the growth and quality of ginger, the physiology indexes significantly decreased compared with the CK from the 2 mg/kg of Cd. Because of this, 2 mg/kg of Cd was chosen for the background value in the subsequent research. To observe the effect of silicon on the growth and quality of ginger under Cd stress, we used 0 g/kg, 1 g/kg, 2 g/kg Si to explore the alleviation effect of varying Si concentrations under 2 mg/kg of Cd stress. The growth of ginger was promoted after the addition of Si under Cd stress (Fig. 1). There is no significant difference among different treatments at 40d, but the difference was significant at the rhizome stage. (Table 3). Also, the yield of ginger improved dramatically under the Si1 and Si2 treatments, which showed an increase of 14.3% and19.5% compared with the CK. Soluble sugar, crude cellulose, soluble protein, free amino acid, and vitamin C increased as the application of Si increased. The effect was the greatest in the Si2 treatment. Application of Si could improve ginger flavor quality. The content of gingerols was improved by 36.8% and 63.2% under Si1 and Si2, compared with the Si0 (Table 4). | 3 |
238085136 | 7 The effect of silicon on Cd content, Cd accumulation in different organ of ginger under Cd stress Cd content was significantly reduced after the addition of Si under 2 mg/kg Cd stress (Table 5). At 40d and 80d, the Cd content of the rhizome and the root was significantly reduced after the addition of Si. At the same time, the Cd content of the stem and the leaves had reduced, but not significantly so. At 120d, Cd content of each part was dramatically decreased after applying Si. The Cd content had reduced from 0.2566, 0.1070, and 0.0580 µg/g, respectively, to 0.1861, 0.0686, and 0.0277 µg/g, respectively, in mother-ginger, son-ginger, and grandson-ginger under the Si2 treatment (Table 5). As Table 6 shows, Cd accumulation in the root and rhizome was less than the CK under the Si1 treatment. The Cd accumulation in the aboveground part changed insignificantly and showed a slightly increasing trend, indicating that Cd accumulation in the aboveground part was promoted after applying Si. The Cd accumulation under the Si2 treatment significantly decreased compared with the CK, indicating that high-concentration Si treatment significantly inhibited Cd accumulation. In conclusion, Si in ginger could promote or inhibit Cd accumulation, depending on the concentration of Si in the soil (Table 6). The effect of silicon on cadmium absorption coefficient and transfer coefficient under Cd stress The primary transfer coefficient under the Si2 treatment was significantly lower than the Si0 and Si1 treatments, implying that higher concentrations of Si inhibited Cd migration from the root to the rhizome ( Table 7). The secondary transfer coefficient under the Si1 treatment was significantly higher than in the Si0 and Si2 treatments, which indicates that the lower concentration of silicon promotes the transfer of Cd from the rhizome to the ground. The root absorption coefficient of the Si2 treatment was significantly lower than in 8 the Si0 and Si1 treatments, which indicates that a high concentration of silicon could dramatically inhibit the root from absorbing Cd from the soil. The aboveground absorption coefficient of the Si2 treatment (0.023) was significantly lower than the Si0 (0.040) and Si1 (0.038) treatments, indicating that a high concentration of silicon inhibited the plant from absorbing Cd from the soil ( Table 7). The ROS level exhibited a rising trend as the treatment days increased (Fig. 4) (Fig. 4). The SOD, POD, and CAT increased as the Si content increased under two mg/kg Cd (Fig. 5). There was a significant difference in the three treatments, and the Si2 treatment was the highest. With the extension of time, the SOD activity of the Si0 treatment gradually decreased. The SOD activity of the Si1 treatment and the Si2 treatment increased and then decreased. At 120d, the SOD activity of the Si2 treatment was the highest, the Si1treatment was second, and the Si0 treatment was the lowest, suggesting that the addition of Si inhibited the SOD activity declining (Fig. 5). The most minor damage to the membrane system in the ginger leaf was in the Si2 treatment, while the Si1 treatment was second. The Si0 treatment showed the most critical damage to the membrane system. During the whole growth stage, the extent of damage was increasingly severe as time went on. At 120d, the MDA content reached the maximum. The MDA of the Si1 treatment and the Si2 treatment was reduced by 14.6% and 20.0% compared with the Si0 treatment which indicates that the damage of the membrane system in the ginger leaf was lower when silicon-containing fertilizer was applied. The Proline content significantly decreased from the Si0 treatment to the Si1 treatment, to the Si2 treatment during the whole growth period (Fig. 6). | 4 |
238085136 | Silicon augmented plant growth and biomass Heavy metal stress can destroy the physiological and biochemical processes in plants Silicon restored photosynthetic efficiency Cd could reduce chlorophyll synthesis, the photochemical quantum yield of ΦPSII, and the CO 2 fixation rate. It was reported that in maize, chlorophyll synthesis and the photochemical quantum yield of ΦPSII decreased under Cd stress [42]. In durum wheat, Cd affected chlorophyll fluorescence [43]. However, the exogenous addition of Si under Cd stress had powerful effects on chlorophyll synthesis and photosynthetic machinery. In our study, the Pn was the least at 13:00, and the Pn of the Si1 and the Si2 treatments were improved by 14.4% and 24.6%, respectively, compared with the CK. Therefore, Si addition under Cd stress alleviated the damage to the ginger plants by weakening the decreasing trend of the Pn under Cd stress (Figure 2). The results were similar in peas, cotton, and maize. In the pea plant, Si addition promoted the contents of chlorophyll pigment and carotene [44]. The same condition occurred in cotton seedlings; the contents of photosynthetic pigments were increased with the addition of exogenous Si [45]. The positive effects of Si on photosynthesis could be due to the destroyed uptake of heavy metals, which could enhance PSI and PSII activation [46]. In maize, Si alleviates Cd toxicity by increasing photosynthetic rate in the modified bundle sheath cells [47]. | 5 |
238085136 | Silicon modulated antioxidant activity Plants could use a series of strategies against the toxic effects of heavy metals under heavy metal stress conditions. The activities of SOD, POD, and CAT are of considerable significance to scavenge the ROS caused by heavy metals [48,49]. Previous studies have reported that Si mediates up-regulation of the antioxidant defense system by increasing the SOD, POD, CAT, and GR activity [50,51].Alleviation of heavy metals toxicity by Si was correlated with protection against oxidative damage. In a previous report, Si could alleviate Cd stress because of a noticeable increase in antioxidant activity and a decrease in MDA in pakochi [52]. In cotton, Si addition could significantly improve the plant's defense capacity against oxidative damage caused by Cd stress. MDA, H 2 O 2 , and electrolyte leakage were reduced, and SOD, POD, APX, and CAT activities were enhanced under Cd stress [45]. In cucumber, the application of Si could eliminate heavy metal Mn toxicity by improving antioxidant activity, according to Shi et al. [53]. Our study showed that SOD, POD, and CAT activities were increased as the Si content 13 increased under Cd stress (Fig.5). At 120d, MDA of the Si1 treatment and the Si2 treatment was reduced by 14.6% and 20.0% compared with the Si0 treatment, indicating that the damage of the membrane system in the ginger leaf was lower when siliconcontaining fertilizer was applied. Proline content was markedly decreased from the Si0 treatment to the Si1 treatment to the Si2 treatment during the whole growth period (Fig.6). At 120d, after applying Si, the Cd content in various organs of the ginger plant was reduced. The Pn of ginger leaves appeared in double peaks in one day, and the diurnal variation trend of each treatment was similar, ranked as Si2 > Si1 > Si0. Overall, our results suggest that Si could alleviate the negative effect of Cd stress on ginger, and the Si2 treatment was the most effective. | 6 |
238085136 | Experimental materials The experiment took place at Shandong Agricultural University at the experimental 14 horticulture station. The ginger variety used was "Laiwudajiang" (WanXing Food company, LaiWu, Shandong Province). The soil tested was pH=7.3, with 100.5 mg/kg alkalihydrolyzed nitrogen (N), 63.4 mg/kg available phosphorus (P 2 O 5 ), and 127.8 mg/kg available potassium (K 2 O). The background value of soil Cd was 0.14 mg/kg. The soil used for the study was air-dried and put into a plastic basin with a 30 cm diameter and a height of 28 cm. Each basin contained 8.0 kg of air-dried soil. The ginger was planted when it germinated to 1cm. Two plants were grown per pot. | 7 |
238085136 | Experimental design The experiment followed the environmental quality standard GB15618-2009.The Cd level was set at zero, one, two, and four mg/kg (soil). There were 10 basins per treatment, and each treatment had three replicates. Varying concentrations of cadmium chloride (CdCl2·2.5 H2O) solution was added to the soil via sewage irrigation once the ginger emerged. The CdCl2·2.5 H2O was applied in this way to ensure the uniform distribution of heavy metals in the soil and to prevent loss from the plastic containers. Other aspects of the experiment were conducted according to the standard method. Samples were collected at the seedling stage, trilling stage, and rhizome expansion stage, respectively (i.e., 40 d, 80 d, and 120 d), after the sewage irrigation treatment, and relevant indexes were determined. Based on the experiment done in the first year, the stress level of Cd was set at two mg/kg (soil), and the amount of silicon fertilizer was zero, one, and two g/kg (soil), respectively. There were 10 pots in each treatment, and each treatment had three replicates. When sowing ginger, the silicon fertilizer mixed with the 10 cm topsoil in a basin. Two mg/kg Cd (in terms of Cd 2+ ) were applied to the soil using the sewage irrigation method when the ginger emerged. The sewage irrigation method was used to 15 ensure that the heavy metals were evenly distributed in the soil and not lost from the pot. Samples were taken at 40 d, 80 d, and 120 d after treatment, and relevant indexes were measured. | 8 |
238085136 | Determination of growth indexes The plants were taken and rinsed with water. Plant height, stem diameter, branch number, leaf number, root, stem, leaf and fresh weight of rhizome were measured. After 20 minutes in the drying oven at 105 ℃, the samples were dried to constant weight at 75 ℃. The dry matter of each organ was measured. | 9 |
238085136 | Determination of quality The volume of soluble proteins, soluble sugars, free amino acids, crude fiber, and vitamin C were measured using various methods. Soluble proteins were measured by staining with Coomassie Brilliant Blue. Soluble sugar content was determined using the anthrone colorimetry technique [54]. Free amino acids were measured using the ninhydrin method [55]. Crude fiber volume was determined by the acid-wash method. And vitamin C was measured using the standard of 2,6-dichloro indophenol [56]. To measure the content of gingerols, 1 g of ginger powder was added to the 100-ml volumetric flask, then 70 ml acetone was mixed into the mixture and shaken for 1 h at 50°C. The mixture was then cooled and diluted with acetone to volume. Filter liquor was used for determining the content of gingerols [57]. | 10 |
238085136 | Funding This study was supported by the National Characteristic Vegetable Industry Technology System Project (Grant No. CARS-24-A-09) and the Shandong Province's dual-class discipline construction project (Grant No. SYL2017YSTD06).The funding organizations provided the financial support to the research projects, but were not involved in the design of the study, data collection, analysis of the data, or the writing of the manuscript. | 15 |
40189029 | A pirólise rápida do ácido oleico foi estudada sobre catalisadores com 10% Ni suportados em sílica e alumina. Os catalisadores foram impregnados com 10% m/m de ácido oleico. Os precursores secos e os catalisadores contendo ácido oleico foram caracterizados por análise termogravimétrica. Os catalisadores calcinados foram analisados por difração de raios X (XRD) e redução à temperatura programada (TPR). As amostras com ácido oleico adsorvido foram submetidos à pirólise rápida a 650 °C. A pirólise de ácido oleico puro levou a 10% de conversão, enquanto a pirólise catalítica resultou em praticamente completa conversão. O catalisador NiO/alumina produziu mais hidrocarbonetos do que o NiO/sílica. Os principais produtos obtidos com NiO/sílica foram 1-alcenos, enquanto que os principais produtos obtidos com NiO/alumina foram isômeros de alcenos e aromáticos, e pequenas quantidades de compostos oxigenados, principalmente álcoois. A pirólise rápida de ácido oleico adsorvido em catalisadoras representa um método útil para distinguir as propriedades dos catalisadores e suas diferentes atividades. | 1 |
40189029 | Introduction Upgrading of vegetable oils and related compounds to obtain liquid fuels has been extensively studied since the end of the 70's.][3][4][5][6] Transesterification is the process usually employed at the industrial level.In this case, vegetable oils react with a short chain alcohol to form esters of fatty acids.These esters are usually named biodiesel.Industrially, methyl esters of fatty acids can be added to petroleum diesel up to 7-8 wt.%.These mixtures, unlike pure petroleum diesel, show a slightly lower energetic power due to their oxygen content and they have limited chemical stability. 7herefore, stabilizers must be added to biodiesel to render it useful. 8,9The thermochemical routes can lead to highly deoxygenated compounds fully miscible with liquid fuels of fossil origin. 5Companies, such as UOP LLC, Neste Oil, Petrobras and Eni S. p. A., have studied hydrocracking of triglycerides with catalysts similar to the ones used in the hydrotreatment processes.For example, Eni S. p. A. and UOP LLC are using the Ecofining™ technology to obtain green diesel, a qualitative biofuel. 10When carried out in the presence of hydrotreating-type catalysts, at hydrogen pressures higher than 3 MPa and at temperatures between 300-400 °C, hydrocracking of triglycerides leads to important amounts of saturated linear hydrocarbons, with a high selectivity towards C16-C18 molecules. 5,11During hydrocracking two main routes have been observed: decarboxylation and decarbonylation (DCO).In both of these reactions the triglycerides are initially transformed into fatty acids that can lose CO 2 and CO + H 2 O, producing hydrocarbons which have a carbon chain with one less C atom than the fatty acid from the initial feed. 5A third reaction is also observed in the presence of hydrogen and is considered as hydrodeoxygenation (HDO).In this case, oxygen is eliminated from the intermediate fatty acid as H 2 O and the main hydrocarbon molecules formed have the same carbon number as the starting fatty acid chain. 5Because the HDO reaction consumes important amounts of hydrogen, studies aiming at favoring DCO over HDO are important.Kubicka and Kaluza 12 showed that hydrotreating-type catalysts containing only Mo species favor HDO during rapeseed oil hydrocracking, whereas the addition of Ni favors DCO.Kubicka et al. 13 also showed that Ni-Mo catalysts with the same composition and the same method of preparation have HDO activity varying with the nature of the support.Therefore, modification of the composition of catalysts appears as an effective way to direct hydrocracking of triglycerides towards DCO. In order to limit hydrogen consumption, cracking of triglycerides and/or model compounds in the absence of added hydrogen has been considered.5][16][17] When using catalysts, the degree of deoxygenation is generally enhanced. 180][21] When the catalysts have strong acid sites, the amount of liquid alkenes and alkanes is decreased whereas important amounts of aromatic compounds are formed. 22umerous studies have considered the use of model compounds to help understand some mechanistic aspects of the decomposition of triglyceride molecules due to their high complexity.2][23][24][25][26][27][28][29] A recent study on the pyrolysis of oleic acid in an autogeneous atmosphere, between 350 and 450 °C, confirmed that both decarboxylation and decarbonylation took place in the reactor, but also revealed internal cracking at the allylic C position, leading to a predominance of C6-C10 hydrocarbons in the liquid products and the formation of C9 and C10 fatty acids. 30The amount of fatty acids decreased when the temperature of pyrolysis was increased, whereas the amount of mono-and poly-aromatic compounds increased.A recent study from our group described the flash pyrolysis of micro amounts of fatty compounds adsorbed on different solid catalysts, NaZSM-5, HZSM-5, g-alumina, SAPO-5 and NiMo/SAPO-5, as a rapid way to screen some catalyst properties and confirm the presence of even minute amounts of products, especially primary reaction intermediates. 31he present work studies the flash pyrolysis of oleic acid, as it is the main fatty acid in most triglycerides taken from vegetable oils.Supported nickel catalysts were used to increase the deoxygenation process.We pre-adsorbed a very small amount of oleic acid on the surface of the catalysts in order to limit the influence of pyrolysis without catalyst.Thus, we could study the role of the catalyst in the initial steps of the decomposition of oleic acid. | 2 |
40189029 | Experimental Preparation of the catalysts Supported nickel catalysts with 10 wt.% Ni (as NiO) were prepared by impregnation with an excess of aqueous solution of nickel(II) nitrate hexahydrate (Merck PA).The supports used were a transition alumina (Pural Sasol), and a commercial silica (Kali Chemie AF125), both in powder form.The solids obtained after evaporation in a rotating device were dried at 110 °C in static air, manually ground for homogenization and calcined under air at 650 °C (heating rate of 10 °C min -1 ) to generate the calcined catalysts precursors.Supports impregnated with pure water were treated in the same way as the supported catalysts in order to have a true reference carrier when necessary. | 3 |
40189029 | Addition of oleic acid onto the catalysts NiO/silica and NiO/alumina after a new drying at 150 °C were mixed with small amounts of pure oleic acid (OA) (Sigma Aldrich > 93%), in a mass proportion of 1 g of catalyst for 0.1 g of OA, under permanent manual agitation to allow complete spreading of the OA.At the end of this "pseudo" impregnation, the catalysts maintained their powder form.They are referred to as OA/NiO/support in the following sections.The use of a high catalyst:reactant ratio was to provide high availability of catalytic sites and minimize the influence of thermal pyrolysis. | 4 |
40189029 | Characterization of the catalysts Pure nickel nitrate and nickel nitrate deposited on both supports at the end of the drying treatment, as well as OA/NiO/silica and OA/NiO/alumina, were characterized by thermogravimetric/differential thermal analysis (TG/DTA) using a Perkin Elmer STA 6000 instrument.The experiments were conducted under a synthetic airflow rate of 20 mL min -1 between 30 and 600 °C at a heating rate of 10 °C min -1 .The reduction of supported NiO was done using a homemade temperature programmed reduction (TPR) equipment, at a heating rate of 10 °C min -1 up to 800 °C, using a mixture of H 2 /argon (1.5 vol.% of hydrogen) with a gas flow rate of 70 mL min -1 .The supports, the calcined NiO supported samples and the reduced catalysts at the end of TPR were characterized by X-ray diffraction (XRD) (Shimadzu diffractometer, model 6000) using the CuKα radiation, between 10 and 80° at a scanning rate of 2° min -1 .The accelerating voltage and the current employed were 40 kV and 30 mA, respectively.The acidity of the catalysts was determined by using pyridine as probe molecule in the same TG Perkin Elmer equipment.An amount of 3 mg of catalyst was pre-treated from 35 to 110 °C for 30 min to remove humidity and then heated to 550 °C at 20 °C min -1 to remove chemisorbed water.After cooling the sample an amount of 1 µL of pyridine per mg of catalyst was carefully added to the catalyst at 120 °C.The desorption of pyridine excess was carried out at the same temperature until reaching equilibrium, after about 60 min.The chemisorbed pyridine was desorbed by heating up to 550 °C at 10 °C min -1 and the loss of mass was recorded with temperature.Specific surface area of the catalysts was determined by the Brunauer-Emmett-Teller (BET) method in a Quantachrome NOVA-2000 equipment at 77 K (-196 °C) with nitrogen adsorption.Samples were pre-treated at 250 °C for 2 h under vacuum before measurement. | 5 |
40189029 | Flash pyrolysis experiments The flash pyrolysis of pure OA and OA adsorbed on both NiO/supported samples were performed in a Pyroprobe CDS-5200 micropyrolysis set up, linked to a gas chromatography/mass spectrometry (GC/MS) analysis system (Shimadzu GC-MS QP 2010 Plus).The powdered sample of the OA/catalyst was placed in a 2 mm × 25 mm quartz tube between quartz wool plugs, in an amount of around 1.0 mg of catalyst with 0.1 mg of impregnated oleic acid.The quartz tube was placed inside a resistive platinum coil heater.The flash pyrolysis was conducted at 650 °C for 0.25 min, at a heating rate estimated as 1000 °C min -1 with a helium flow rate through the sample of 150 mL min -1 .After pyrolysis, the vapors and gases flowed to the GC injector through a transfer line heated at 170 o C, as shown in Figure 1.The chromatographic analysis was performed in a DB-5MS analytical column (30 m × 0.25 mm × 0.25 µm), with a helium flow rate through the column of 1 mL min -1 .The column program was 5 min at 45 °C, heating to 280 °C at a heating rate of 4 °C min -1 , with a 10 min stay at 280 °C.The ion source was maintained at 280 °C and the interface at 290 °C.The m/z data were measured between 40 and 400.The chromatographic peaks of the pyrolysis products were identified using the National Institute of Standards and Technology (NIST) library standards as well as comparing with data from the literature.The probability of products identification was better than 90% for the great majority of the peaks.The standard deviations of the main peaks in some replicated experiments were smaller than 25%.are attributed to water loss, whereas the high temperature event is due to NO x release. 32,33Above 650 °C, no further mass loss was observed suggesting a complete decomposition of pure nickel nitrate to nickel oxide.In the presence of both supports, a first mass loss ending between 150 and 170 °C is attributed to water release from the support.Further mass losses vary with the nature of the support, a clear mass loss process appearing only with nickel nitrate deposited onto silica, with a maximum rate at around 270 °C.The other steps are not well resolved.Table 1 shows the mass loss percentage from the decomposition of pure or supported nickel nitrate on silica and alumina, obtained from the TG curves.Figure 2 and Table 1 show that the decomposition temperature of the nickel nitrate for the release of NOx follows the order: NiO/alumina > NiO/silica.This suggests that the interaction of the nickel with alumina is higher than with silica. | 6 |
55253853 | Nowadays, the uncontrolled use of antibiotics has created the problem of bacterial resistance to them, what has motivated the search for new alternatives of drug for the treatment of bacterial diseases. Here, we compare antimicrobial activity of spent substrate of mushroom Pleurotus ostreatus and Lentinula edodes, against Escherichia coli, Salmonella tiphymorium, Staphylococcus aureus and Micrococcus luteus. We designed two mixtures, barley straw to be used as a substrate of cultivation of mushroom Pleurotus ostreatus and oats or cedar for the cultivation of mushroom Lentinula edodes; and were obtained aqueous extracts from spent substrates; extracts were tested for antibacterial activity. The protocol was a completely randomized assay with a factorial arrangement design. The data were analyzed with PROC GLM, SAS. The results showed that in the case of Escherichia coli the greatest inhibition zone was of 12.66 mm at a concentration of 6 mg mL, with treatment of Lentinula edodes/Cedar; Salmonella tiphymorium showed a greatest inhibition zone of 31.10 mm to a concentration of 5.12 mg mL, with treatment of Pleurotus ostreatus/Barley straw; Staphylococcus aureus showed a greatest inhibition zone of 9.33 mm to a concentration of 100 mg mL, with the treatment of Lentinula edodes/Cedar and finaly, Micrococcus luteus showed a greatest inhibition zone of 15.00 mm to a concentration of 50 mg mL, with the treatment Lentinula edodes/Oats. In conclusion, the results suggest that it is possible to use indistinctly the spent substrate of Pleurotus ostreatus and Lentinula edodes as source of extracts with antibacterial activity. | 1 |
55253853 | Introduction The uncontrolled use of antibiotics has caused serious problems in human and animal health, causing that bacterias develop resistance to them, so World Health Organization considered to infections caused by bacteria resistant to drugs as a public health problem; therefore, it is necessary to find new pharmacological strategies, among which we can find natural products such as plants and fungi (Roca et al., 2015). Spent mushroom substrate containing carbohydrates as cellulose and hemicellulose, lignin, remnant of edible fungi, is a byproduct of mushroom production industry.Substrate used as growth media to produce mushroom is composed of maize cobs, wheat straw, grass straw, sugarcane bagasse, field hay, corn cobs, cotton seed hulls and some other.After several mushroom harvesting cycles, the productivity of the substrate could decrease so that the substrate is declared as spent (Guoa & Choroverb, 2006;Onyango, Palapala, Arama, Wagai, & Gichimu, 2011).One of the main problems in the production of mushrooms still the treatment and disposal of spent mushroom substrate; many studies have already been carried out for the use of such substrates, among which we mention feeding and/or antimicrobial activity (Zhu, Sheng, Yan, Qiao, & Lv, 2012). The fungi have an important role in the degradation of organic matter (Chang & Miles, 1984), in addition to being a source of bioactive substances to produce antibiotics or pharmaceutical drugs, such as functional food and additives in feeding stuffs (Santoyo, Ramírez-Anguiano, Reglero, & Soler-Rivas, 2009).Crop of mushrooms (Pleurotus ostreatus) it is a source of products agricultural, their organic waste generated can be used as a source of food with high protein content and as an alternative pharmaceutical treatment; Pleurotus ostreatus is a fungus that has the ability to grow on agricultural wastes, accelerates the biodegradation and recycling them, avoiding its burning and the subsequent environmental pollution (Varnero, Quiroz, & Álvarez, 2010).Lentinula edodes, fungi edible, is the most studied, has been shown that fruiting body and mycelium have antimicrobial properties; likewise, the lentine inhibits mycelium growth of other fungi as Physalospora piricola, Mycosphaerella arachidicola and Botrytis cinerea (Rojas, 2013;Romero-Arenas, Martínez, Damian, Ramírez, & López-Olguín, 2015). The production of mushroom has been used with a large number of substrates; one of the main is straw, used as a source of carbon to increase the nutritional characteristics and palatability of the fruiting body, getting a better nutritional quality (Sánchez, 2010).The crop of fungi and the quick growth in mushroom production worldwide has resulted in large quantities of spent substrate mushroom (about 13.6 million t year -1 ).The massive amounts of waste can cause environmental problems; this causes, led more research to develop technologies for its treatment or use (Lin et al., 2014). In recent years, there has been a need study antimicrobial phytochemicals with potential to generate new pharmacological options.Our group previously demonstrated that the use of spent substrate of Pleurotus ostreatus mixed or not with medicinal plants, has antibacterial activity (Ayala et al., 2015).Therefore, the objective of this study was to determine the antibacterial activity of spent substrate of Pleurotus ostreatus and/or Lentinula edodes against Escherichia coli, Salmonella tiphymorium, Staphylococcus aureus and Micrococcus luteus at different concentrations. | 2 |
55253853 | Strain, Substrates and Cultivation Mushrooms The blocks (1 Kg) were obtained from Centro de Investigaciones Biológicas of the Universidad Autónoma del Estado de Hidalgo, México.The blocks were formed by a mixture of barley straw; which were purchased in Central Abastos in Pachuca Hidalgo, Mexico, the taxonomic identification did it the botanist Dr. Miguel Angel Villavicencio Nieto; the specimens were deposited at the Herbarium of the Centro de Investigación de Ciencias Biológicas, of the Universidad Autónoma del Estado de Hidalgo, México.To form the substrate, barley straw was colonized with mycelium of Pleurotus ostreatus UAEH-004 in solid substrate fermentation; mushrooms were harvested at 23 d and was obtained spent substrate; on the other hand, oats or cedar were colonized with mycelium of Lentinula edodes UAEH-015 in solid substrate fermentation; mushrooms were harvested at 90 d and were obtained spent substrate of each one. | 3 |
55253853 | Preparation of Organic Extracts The extracts were obtained by mixing 100 g of spent substrate mushroom of each treatments and 300 mL distilled water in case of Pleurotus ostreatus and 600 mL distilled water in case of Lentinula edodes.Then, the mix was macerated in blender during 1 min.Subsequently, mix macerated was filtered using gauze, to separate solid and liquid parts, was filtered through filter paper Whatman® #41.The extract was placed in a water bath to 70 °C for 48 h, to obtain the sample dry; for each 25 ml of liquid extract were obtained 0.472 g of Pleurotus ostreatus and 0.451 g of Lentinula edodes of dry extract. | 4 |
55253853 | Antimicrobial Assay The antibacterial activity of the spent substrate of Pleurotus ostreatus and/or Lentinula edodes extracts were studied by the method of paper disc diffusion assay with slight modification (Kil et al., 2009).The bacterial pathogens strain were grown in liquid medium for 24 h to yield a final concentration of Escherichia coli 7.7 × 10 6 CFU/200 µL, Salmonella tiphymorium 1.11 × 10 7 CFU/200 µL, Staphylococus aureus 1.0 × 10 7 CFU/200 µL and Micrococcus luteus 1.04 × 10 7 CFU/ 200µL.Next, aliquots of 0.1 ml of the test microorganisms were spread over the surface of agar plates.Sterilised filter paper discs of 6 mm diameter (paper Whatman® #41) were saturated with 50 μl of different concentrations (0, 6, 12.5, 25, 50 and 100 mg mL -1 ) spent substrate of Pleurotus ostreatus and/or Lentinula edodes extracts.The soaked discs were then placed in the middle of the plates and incubated for 24 h at 37 °C (Forma Series II Water Jacket CO 2 , Incubator, Model 3100, Thermo Scientific, USA), after which the diameter (in mm) of each inhibitory zone was measured (scalimeter).Negative control was prepared with distilled water; as positive control was used commercial antibiotic (Penicillin G sodium salt, Sigma-Aldrich, St. Louis, MO, USA) to a concentration 100 mg mL -1 on medium culture Mac Conkey and Estafilococos No. 110. | 5 |
55253853 | Results Treatment with spent substrate of Pleurotus ostreatus and Lentinula edodes extracts were effective against four bacterial strains tested; antibacterial activity at different concentrations is showed in Table 1; the tested bacteria were quantitatively assessed by measuring the diameter of inhibition generated for each sample; each result is the mean of three replicates.The results showed that the spent substrate Pleurotus ostreatus/Barley straw extracts presented highest inhibitory effect against Escherichia coli (7.7 × 10 6 CFU/200 µL) at a concentration of 12.5 mg mL -1 with 9.86 mm inhibition halo; Staphylococus aureus (1.0 × 10 7 CFU/200 µL) at a concentration of 25 mg mL -1 with 9 mm inhibition halo and Micrococcus luteus (1.04 × 10 7 CFU/ 200µL) at a concentration of 50 mg mL -1 with 9.66 mm inhibition halo.Salmonella tiphymorium (1.11 × 10 7 CFU/200 µL) at a concentration of 12.5 mg mL -1 with 31.10 mm inhibition halo, showing significant differences with the concentrations 6, 25, 50 and 100 mg mL -1 (P < .05). When comparing the largest zone of inhibition of the three treatments tested (Pleurotus ostreatus/Barley straw, Lentinula edodes/Oats y Lentinula edodes/Cedar) against each bacteria (Table 2), the results showed in the case of Escherichia coli the largest zone of inhibition was at a concentration of 6 mg mL -1 (12.66 mm) with treatment of Lentinula edodes/Cedar; Salmonella typhimurium showed the largest zone of inhibition at a concentration of 5.12 mg mL -1 (31.10 mm) with treatment of Pleurotus ostreatus/Barley straw; Staphylococcus aureus showed the largest zone of inhibition at a concentration of 100 mg mL -1 (9.33 mm) with the treatment of Lentinula edodes/Cedar and Micrococcus luteus showed the largest zone of inhibition at a concentration of 50 mg mL -1 (15.00 mm) with treatment of Lentinula edodes/Oats.Salmonella typhimurium and Staphylococcus aureus no showed significant differences between each treatments; Escherichia coli treated with Lentinula edodes/Oats is significantly different to the treatment Lentinula edodes/Cedar (P < 0.05), but without showing difference significant with treatment Pleurotus ostreatus/Barley straw, while Micrococcus luteus treated with Lentinula edodes/Oats is significantly different with treatment of Lentinula edodes/Cedar and Pleurotus ostreatus/Barley straw (P < 0.05). | 7 |
55253853 | Discussion In recent years the bacteria have acquired the ability of multi-resistance to antibiotics (Nehra, Meenakshi, & Yadav, 2012) which has generated that recent research are focus in the search for alternative treatments, such as fungi.Edible fungi such as Pleurotus ostreatus, have shown a high nutritional value as food (Patel, Naraian, & Singh, 2012) and anti-inflammatory, antidiabetic, antiviral, antioxidant, anticancer, antitumor, inmunomodulatory and antibacterial activity; however, most of the research has been based on the study of the fruiting body and not in spent substrate (Hearst et al., 2009;Deepalakshmi & Mirunalini, 2014). A water-soluble polysaccharide named PL was isolated and purified from spent mushroom substrate, the polysaccharide contained two fractions (PL1 and PL2), composed of glucose, rhamnose and mannose; the antibacterial activity of polysaccharide against E. coli was the strongest, while the weakest against Sarcina lutea, the minimal inhibition concentrations of PL2 were 12.5, 25 and 100 μg/mL, respectively (Zhu et al., 2012).We show that aqueous extract of spent substrate of Pleurotus ostreatus/Barley straw has antibacterial activity against Escherichia coli (9.86 mm), Staphylococcus aureus (9.00 mm), Micrococcus luteus (9.66 mm) and Salmonella tiphymorium (31.10 mm), similar to that obtained using extracts of mushroom Pleurotus ostreatus obtained with different organic solvents (24.56 and 14 mm) for Gram positive and Gram negative bacteria (Nehra et al., 2012). For the cultivation of Lentinula edodes for many years have used various agricultural and industrial wastes, among which we mention sorghum, sugar cane, sawdust, oak, cedar (Grodzínskaya et al., 2002) as carbon source; shiitake mushrooms (Lentinus edodes) is of great importance, due to its attributed not only to its nutritional value, but also potential applications in industrial food and medicine as antibacterial (Hearst et al., 2009) and/or antitumor, among other features; this activity is due to the lentina (one polysaccharide isolated from fruiting body), which acts as an enhancer of host defense; has shown action against Staphylococcus aureus, Bacillus subtilis and Escherichia coli (Hatvani, 2001).Chowdhury, Kubrai, and Ahmed (2015) mentioned antimicrobial activity of 3 edible mushrooms (Pleurotus ostreatus, Lentinula edodes, Hypsizigus tessulatus) methanolic extracts, indicated considerable activity against bacteria and fungi, reveling zone of inhibition ranged from 7 ± 0.2 to 20 ± 0.1 mm; Kazue, Megumi, and Dantas (2001) found that the mycelium of 35 different strains of Lentinus edodes, has antibacterial activity against B. subtilis, with inhibition halos 5-20 mm in diameter similar to our findings. This work is novel because for the first time is studied the use of spent substrate Lentinula edodes as antibacterial, since only been shown this activity in the fruiting body; they have been used different extraction techniques: high-pressure operations and low-pressure methods.The high-pressure technique was applied to obtain Lentinus edodes extracts using pure CO 2 and CO 2 with co-solvent or organic solvents such as n-hexane, ethyl acetate and dichloromethane (Kitzberger, Smânia Jr., Pedrosa, & Ferreira, 2007); here it is included barley straw as a substrate for the cultivation of Pleurotus ostreatus and oats or cedar for the cultivation of Lentinula edodes, in order to obtain aqueous extracts and determine its antibacterial activity; the findings suggest that it is feasible to use these substrates in the future for obtain antibacterial pharmaceutical compounds and at the same time reduce the pollution by their accumulation. | 8 |
5300972 | Os extratos de alcalóides de Lupinus spp., obtidos por métodos convencionais (maceração/ sonicação – extração em fase sólida; maceração/sonicação –extração líquido-líquido) e por SFE (extração com fluido supercrítico) usando CO2 e CO2 modificado (CO2/MeOH, CO2/EtOH, CO2/iPrOH e CO2/H2O) foram analisados por CGAR-DIC (cromatografia gasosa de alta resolução com detector de ionização de chama) e CGAR-EM (cromatografia gasosa de alta resolução acoplada à espectrometria de massas). As análises quantitativas por CGAR-DIC foram feitas pelo método do padrão interno, para a quantificação de lupanina, multiflorina e um alcalóide derivado da esparteína. CGAR-EM permitiu a identificação dos constituintes químicos (alcalóides e outras substâncias) destes extratos. | 1 |
5300972 | Introduction Lupinus spp.has been investigated in several countries as a potential alimentary source due to its relatively high protein and oil content (35 -40% and 8 -12%, respectively), high productivity and low cost.Although lupine protein levels are similar or larger than that of the soya bean, the main problem is the quinolizidine alkaloids, which are known to provide a bitter taste and toxicity to the seeds.An usual procedure for the elimination of these alkaloids is washing the seeds with flowing water; despite simple, this method requires large volumes of water for the commercial scale Lupinus processing [1][2][3] .SFE (supercritical fluid extraction) is a valuable method both for industrial scale food processing and also for analytical scale studies, as an alternative extraction method to reduce the use of liquid solvents (mainly organic solvents).However, analytical scale SFE of polar compounds is still underexplored, mainly due to the low diffusibility and low polarity of supercritical CO 2 .Some moderately polar natural products such as alkaloids and flavonoids have been extracted by SFE 4,5 . In this work, the extraction of Lupinus spp.alkaloids by SFE is compared with conventional methods (maceration/sonication -solid phase extraction, and maceration/sonication -liquid-liquid extraction).The extracts were analysed by HRGC-FID (high resolution gas chromatography -flame ionisation detector), for the quantification of lupanine, multiflorine and a spartein-like alkaloid.HRGC-MS (high resolution gas chromatography coupled with mass spectrometry) analysis allowed the identification of the chemical constituents (alkaloids and other compounds) from the extracts obtained by different methods from Lupinus samples obtained from markets in São Paulo, SP. | 2 |
5300972 | Sample extraction: SFE Supercritical fluid extractions were performed on an analytical scale "home-made" system, previously described 6 .Powdered Lupinus samples (0.5 g each) were extracted for approximately 20 minutes in a dynamic mode, using as extraction fluids pure CO 2 or CO 2 modified with different solvents, as indicated in Table 1. All the extracts were collected in analytical grade CH 2 Cl 2 (Merck, Darmstadt, Germany) contained in a test tube, in an ice bath.The solvent was removed at room temperature, under nitrogen flux, followed by drying in a vacuum oven at room temperature until constant weight.Whenever possible, extractions were made in triplicate (see remarks in Tables 2 and 3).Residues were dissolved in analytical grade methanol (Merck, Darmstadt, Germany) prior to HRGC analysis. | 5 |
5300972 | Clean up Clean up was done by percolating the extract (obtained by conventional extraction or SFE), solubilized in 5.0 mL analytical grade methanol, through a glass Pasteur-type pipette containing 0.5 g silica gel 60, 70 -230 mesh (Merck, Darmstadt, Germany) and 0.5 g active charcoal (Reagen, Rio de Janeiro, Brazil). Extracts obtained by SFE using aqueous mixtures have been submitted to SPE (solid phase extraction), using Sep-Pak C-18 cartridges (Waters), preconditioned with 8.0 mL methanol followed with 8.0 mL H 2 O.The extract was Sequential mode extractions were done firstly with pure CO 2 , followed by extraction of the same Lupinus sample using CO 2 modified with 10% EtOH.Temperature and pressure conditions of each step were as reported in Table 1.percolated through the cartridge and eluted with methanol, acetone, ethyl acetate and chloroform, successively (8.0 mL each).These fractions were collected and combined for total yield determination and chromatographic analysis.Some samples were not submitted to the clean up step and were directly analyzed by HRGC; they are indicated in Table 3. | 6 |
5300972 | Chromatographic analysis HRGC-MS analyses were performed using a HP 5970 mass selective detector (Hewlett -Packard, USA), (EI, 70 eV), coupled to a HP 5890 GC.The column used was a 95% methyl, 5% phenylpolysiloxane, LM-5 (50 m x 0.25 mm x 0.65 mm) supplied by L & M (São Carlos, Brazil).Samples were injected using the split mode (1:30), with injector temperature and HRGC-MS interface temperature both at 300°C.The column temperature was programmed to rise from 170 °C (3.5 min), at 6 °C min -1 , to 300 °C (held during 20 min).Helium was used as carrier gas, at the average linear velocity of 35 cm sec -1 ; MS data were processed using a CPU HP 7946 / HP 9000-300.Tentative identifications were made by comparison of the obtained spectra with literature data 7,8 .The HRGC-FID analyses were performed on a HP 5890 GC, using the same column and the same temperature program as used for the HRGC-MS analysis.Detector (FID) temperature was 320 °C, split (1:30), injector temperature was 280 °C, data were obtained on HP 3396 A integrator.Hydrogen was used as the carrier gas, at an average linear velocity of 40 cm sec -1 .All quantitative analyses were made by the internal standard method, using caffeine as an analytical standard.The Lupinus extracts were diluted to 1.0 mL in methanol, and 0.3 mL of a caffeine standard solution (1 mg mL -1 ) was added to the sample, which was analyzed by HRGC-FID.For each alkaloid quantified a corresponding calibration curve was prepared (injections in triplicate for each concentration), and linearity for internal standard quantification was checked within the range of 0.05 -0.50 mg caffeine mL -1 . | 7 |
5300972 | Extraction methods The yields for each extraction procedure were determined using both Brazilian commercial and Chilean samples (Table 2).The conventional extraction gave a similar yield, both by Extrelut preconcentration and liquid-liquid extraction (Figure 1).Most of the SFE procedures gave better yields than the conventional method.Some of the SFE experiments showed a large standard deviation, due to some specific problems of some fluid mixtures.For example, water extracted polar compounds, which plugged the system due to the production of foam.Another problem was the trapping of CO 2 extracts: losses of extracts due to plugging (ice formation in the extremity of restrictor) are inherent to extract collection in solvents (the process herein adopted).The time required for SFE was 20 minutes for each extraction while for conventional methods the total time was several hours for the complete procedure. | 8 |
5300972 | Chemical composition of the extracts HRGC-MS analysis of the extracts obtained from a commercial Lupinus sample allowed tentative identification of three alkaloids, by comparison with literature data 7 : lupanine (1), multiflorine (2) and a spartein derivative (3).Many other compounds were identified as alkaloids, but a more detailed tentative identification was not possible.The main feature of these unidentified alkaloids was a peak at m/z = 58, which is found in several lupane-type alkaloids 7 .Some extracts also contained other compounds, mainly fatty acids and long chain hydrocarbons, which were identified by their MS profiles 9 .The CO 2 /H 2 O mixture required slightly stronger conditions, since the critical constants of H 2 O are significantly higher than those of organic solvents 10 .SFE using CO 2 modified with 5% H 2 O was the most selective condition for alkaloid extraction; however, the critical conditions of this mixture (Pc = 89.1 atm, Tc = 69.1 o C; calculated according to the literature 11 ), require a relatively high temperature for the usual working conditions with natural products.SFE using CO 2 modified with 10% methanol showed the best yield with a lower temperature (Pc = 73.7 atm, Tc = 60.0 o C). Figure 2 (peaks key on Table 3) shows the TIC-HRGC-MS profile of these two extracts. | 9 |
5300972 | Quantitative analysis Quantitative analyses were made for the main alkaloids.Lupanine was found in all of the Lupinus extracts.The regres-sion equations for the analytical curves were y= 0.0359 + 0.6647 x (r=0.999) for lupanine (1), y= -0.0236 + 0.1126 x (r= 0.999) for multiflorine (2) and y= 0.06203 + 0.02893 x (r= 0.968 ) for the spartein derivative (3).The average percentage standard error for the peak areas for replicate injections was less than 5%, showing good reproducibility.The content of each alkaloid in all Lupinus extracts is shown in Table 3. The sum of the alkaloid content in the extract obtained by SFE using CO 2 modified with 10% ethanol and not submitted to clean-up before HRGC-FID was the greater of all extraction methods.Unfortunately EtOH usually shows problems in reproducibility as a SFE modifier, since commercial ethanol has a significant (for SFE) variation in water content. Utilization of isopropanol as a modifier showed no significant improvement in extraction process (yield or selectivity), so this solvent should be considered only as a third option in the choice of modifiers, due to its cost and the difficulty of removing residual solvent from extracts. | 10 |
54744402 | An efficient and convenient method was developed for synthesis of 2-amino-3-cyanopyridine derivatives via the four-component coupling reaction between ketone, aldehyde, malononitrile, and ammonium acetate in the presence of 2 mol% copper nanoparticles on charcoal (Cu/C) catalyst. A variety of ketones and aldehydes was used to afford the corresponding products in good to excellent yields. The method is applicable to large-scale operation without any problem. The catalyst could be quantitatively recovered from the reaction mixture by simple filtration and reused at least eight times with almost consistent activity. | 1 |
54744402 | Introduction 2][3] Polysubstituted pyridines possess important biological and pharmacological activities and could be used as potential agrochemicals, for example as herbicides. 4In addition, the molecules containing pyridine moiety are used as non linear optical materials, 5 electrical materials, 6 and chelating agents in metal ligand chemistry. 7Among them, 2-amino-3-cyanopyridines are known as IKK-β-inhibitors. 8hey have been identified to possess multiple biological activities such as antimicrobial, 9 antiviral, 10 antibacterial, 11 antifungal, 12 antitumor, 13 anti-inflammatory, 14 as well as antihypertensive 15 properties.Besides, they are important and useful intermediates in preparing a variety of heterocyclic compounds. 12,16he interesting biological properties of these compounds have promoted a great deal of research effort toward development of new synthetic methodologies for the preparation of 2-amino-3-cyanopyridines and their derivatives.Therefore, the synthesis of 2-amino-3cyanopyridine derivatives continues to attract much interest in organic chemistry. A survey of the literature shows that the major synthetic approaches that are used to prepare various types of 2-amino-3-cyanopyridine derivatives involve utilization of corresponding 2-chloro derivatives as substrates, 17 chalcones on treatment with ammonium acetate via the condensation reaction, 18 as well as via a one pot four components reaction 19,20 in conventional heating or under microwave irradiation, and also by some other methods. 21,22n recent efforts to develop more facile methods for the synthesis of 2-amino-3-cyanopyridines, metal-catalyzed reactions have been developed. 19n recent years, the use of heterogeneous catalysts has received considerable interest in organic synthesis.Using heterogeneous catalysts in synthetic organic routes has some advantages over their counterparts, such as great durability toward the reaction conditions, having highly active sites, recyclability and reusability of catalyst. 23][26] Based on the above mentioned reports and in continuation of our efforts to develop facile and general methods for the preparation of 2-amino-3-cyanopyridine derivatives, and as a part of our studies to utilize heterogeneous catalyst for the synthesis of organic compounds, [27][28][29][30][31] here we wish to report a heterogeneous catalyst system based on Cu/C and illustrate its application for the synthesis of 2-amino-3-cyanopyridine derivatives without any cocatalyst or activator under mild conditions.recorded on a Bruker Avance DPX-250 spectrometer ( 1 H NMR at 250 MHz and 13 C NMR at 62.5 MHz) in pure deuterated solvents with tetramethylsilane (TMS) as an internal standard.Infrared (IR) spectra were obtained using a Shimadzu FTIR 8300 spectrophotometer.Mass spectra were determined on a Shimadzu GCMS-QP 1000 EX instrument at 70 or 20 eV.Elemental analyses were performed with a Thermo Finnigan CHNS-O 1112 series analyzer.Melting points were determined in open capillary tubes in a Büchi 535 circulating oil melting point apparatus.The purity determination of the substrates and reaction monitoring were accomplished by thin-layer chromatography (TLC) on silica gel PolyGram SILG/ UV 254 plates.Column chromatography was carried out on short columns of silica gel 60 (70-230 mesh) in glass columns (2-3 cm diameter) using 15-30 g of silica gel per g crude mixture.Chemical materials were purchased from Fluka, Aldrich and Merck.The used activated carbon was also purchased from Merck (Art.No. 9631, 0.3-0.05mm). | 2 |
54744402 | Synthesis of copper nanoparticles on charcoal (Cu/C) The activated carbon (1.0 g) was refluxed in nitric acid solution (5.0 mol L -1 , 30 mL) for 6 h, washed with deionized water until pH 6-7 and finally dried in an oven at 110 °C for 12 h under vacuum.For the synthesis of Cu/C, CuI (100 mg) was dissolved in absolute ethanol (30 mL), and stirred at reflux temperature for 4 h under nitrogen atmosphere in the presence of 1.0 g of purified activated carbon.The resulting solid was washed with ethanol (4 × 30 mL).Finally, the copper in charcoal was dried under vacuum in an oven overnight at 110 °C. 24neral procedure General procedure for the synthesis of 1-17 A 25 mL flask was filled with the mixture of substituted aldehyde (1.0 mmol), ketone (1.0 mmol), malononitrile (1.5 mmol), ammonium acetate (2.0 mmol), Cu/C nanocatalyst (2.0 mol%) and then stirred in acetonitrile (2.0 mL) at 80 °C under ambient atmosphere.Progress of the reactions was monitored with TLC using n-hexane/ ethyl acetate (10:1).After completion, the crude reaction mixture was filtered through a pad of Celite and washed with hot ethanol (3 × 10 mL).The recovered catalyst was dried under vacuum at 40 °C for 5 h and stored for another consecutive reaction run, and the combined filtrates were concentrated in vacuo and the resulting residue was purified by silica gel column chromatography employing n-hexane/ ethyl acetate (10:1) as eluent. | 3 |
54744402 | 2-Amino-4,6-diphenylnicotinonitrile (1) White solid; m.p. 176-177 °C; IR (KBr) ν max / cm -1 3465 (w), 3379 (w), 3306 (w), 3181 (w), 2207 (s), 1641 (s), 1585 (s), 1574 (s), 1550 (m), 1497 (w), 1452 (w), 1370 (w), 1259 (w), 759 (s), 699 (s); 1 We commenced our investigation with the reaction of starting materials in chloroform as solvent in the presence of Cu/C as a catalyst.Analysis of the resulting mixture revealed that the desired product 1 was formed after 6 h in only 10% yield (Table 1, entry 1).Yield of the reaction increased upon using N,N-dimethylformamide (DMF) instead of chloroform (entry 2 vs. 1).Replacement of DMF with ethanol (entry 3) did not give an improved outcome, while the formation of product 1 was markedly improved when using the same catalyst in acetone at reflux condition (entry 4).Further condition screening suggested that when the reaction was carried out in the presence of Cu/C, upon switching the solvents from acetone to ethyl acetate, tetrahydrofuran (THF) or polyethylene glycol 300 g mol -1 (PEG 300), the yield of desired product decreased (entries 5-7).However, when the reaction was carried out in toluene at reflux condition for 6 h, the expected product was achieved in 76% yield (entry 8).Interestingly, when model compounds were treated with 2 mol% of Cu/C in acetonitrile at reflux for 6 h, the expected reaction proceeded successfully to give product in 91% yield (entry 9).A further decrease in the catalyst loading resulted in 74% isolated yield (entry 10), but increase in the catalyst loading did not enhance the reaction yield any further (entry 11).Further optimization of the reaction conditions revealed that other Cu sources regardless of their oxidation states (either I or II) did not show better catalytic activity (entries 12 and 13).We speculate that the observed higher yields are probably due to the large surface area and more stability of the formed nanoparticles of Cu/C.In addition, CuI showed lower yield in comparison with Cu/C under these reaction conditions.It is possibly due to the disproportionation of this salt under optimization reaction condition.When this reaction was carried out in acetonitrile at reflux condition for 6 h, without any catalyst, no desired 2-amino-3-cyanopyridine was obtained (Table 1, entry 14).Next, experiment was carried out to distinguish the effect of temperature on the reaction.As depicted in Table 1, the desired product could not be detected at room temperature (entry 15).In addition, control experiments demonstrated that no reaction occurred in the presence of charcoal as a catalyst (entry 16). After the optimization reaction conditions, in order to examine the scope of the reaction, we treated various aldehydes and methylketones in the presence of malonitrile and NH 4 OAc with Cu/C in refluxing acetonitrile, and desired 2-amino-3-cyanopyridine derivatives were obtained in good to high yields (Table 2). From the results shown, aldehydes with both electronwithdrawing and -donating substituting groups afforded the 2-amino-3-cyanopyridine derivatives through reaction Vol.27, No. 4, 2016 with acetophenone, malononitrile and ammonium acetate and the isolated yields range from 86 to 94% (Table 2, entries 2-5).In an effort to apply the present reaction conditions to the synthesis of heterocycles related to 2-amino-3-cyanopyridines, the feasibility of the reaction with heteroaromatic aldehyde was examined (entry 6).It is noteworthy that the reaction of 3-thiophenecarbaldehyde as a heterocyclic aldehyde proceeded well to give the desired products in 86% yield.To expand the scope of the current method, aliphatic aldehyde was also examined as a substrate.The desired product 7 was obtained with good yields (entry 7).We further explored the potential of the present protocol from the standpoint of variety of ketones.As seen from Table 2, this strategy is effective for a great diversity of ketones such as alkylaryl (entries 8-11), cyclic (entries 12 and 13), and dialkyl ketones (entries 14-17).Acetophenone with both electron-withdrawing and -donating substituting groups fairly tolerate the reaction conditions and also afford the desired products in good yields (entries 8-10), and proves the generality of the strategy elaborated.The highly conjugated ketone derivative was also an excellent substrate for this reaction, and the corresponding compound 11 was produced (entry 11).For cyclic ketones, this transformation proceeded smoothly and afforded the products in good yields.For example, the reaction of cyclohexanone or 4-methyl cyclohexanone led to the corresponding products in 84 and 86% isolated yields, respectively (entries 12 and 13).To our delight, this method could be successfully applied to dialkyl ketones.For example, the product having t-butyl, isopropyl or methyl groups derived from the corresponding methyl ketone was formed in satisfactory yield (entries 14-16).Meanwhile, methyl acetoacetate also reacted with benzaldehyde and generated the corresponding product 17 in 85% yield (entry 17). In addition, to evaluate the feasibility of this method on a large scale, the model reaction was performed on the 40 mmol scale and the desired product was obtained in 89% yield. Next, we studied the reusability of the heterogeneous nano Cu/C catalyst in the model reaction (Table 3).After completion of the reaction, the catalyst was filtered from the reaction mixture, washed with hot ethanol, dried and used directly for the next round of reaction.The ease of recovery, combined with the stability of catalyst, allows the catalyst to be recycled over 8 times in reactions without any significant loss in activity. | 4 |
97099960 | Uma nova família de ésteres tiazolínicos e tiazóis foram sintetizados e as propriedades térmicas são apresentadas e discutidas. Os ésteres tiazolínicos foram obtidos pela reação de ciclização de benzonitrilas 4-substituídas com o amino ácido L-cisteína seguido da reação de esterificação com álcoois e fenol previamente selecionados. A oxidação dos ésteres tiazolínicos mediado pelo reagente BrCCl3/DBU permitiu a transformação dos respectivos ésteres tiazolínicos em ésteres tiazóis . Os compostos finais dos ésteres tiazolínicos e tiazóis são formados por cadeias alquílicas, (perfluoroalquil)alquílicas e p-alcoxifenilas. Alguns cristais líquidos mostraram serem mais relevantes. Um deles apresentou mesofase esmética A (SmA) monotrópica enquanto que outros apresentaram mesofase estável SmA. Como esperado, as cadeias de alcanos semifluorados induziram a formação de mesofase ortogonal via efeito de segregação. | 1 |
97099960 | Introduction Liquid crystals (LC) have been long recognized as one of the most extensive and attracting fields of materials research.The first studies, dating from 150 years ago, prompted nowadays researches worldwide increasing scientific interest, focusing on obtaining and monitoring new LC compounds. 1he most common application of liquid crystal technology is in liquid crystal displays (LCDs).From the ubiquitous wrist watch and pocket calculator to an advanced computer screen, this type of display has evolved into an important and versatile interface.Since the discovery of interesting electro-optical properties in the middle sixties and the production of the first LCD panel in the beginning of the seventies, many other practical applications of these molecules have been largely studied. As they show a variety of physical properties, these molecules find application in diverse fields of science, such as display technologies, 2 light emitting diodes 3 and photo/semiconducting materials. 4Thus, great effort has been made in developing synthetic strategies for acquisition of new and diverse mesomorphic compounds. Heterocyclic compounds are of great importance in many fields of chemistry.It is very common the observation of interesting biological activity on compounds bearing these structures. 5Insertion of a heterocyclic unit in the skeleton of a mesogenic molecule aggregates many advantages, once one could enhance design possibilities and count up several changes in liquid crystalline properties.Also it is well-known that a minor change in molecular geometry may bring about substantial variations on mesomorphic behavior. 6Furthermore, the presence of heteroatom alters considerably the polarity and polarisability of the molecule, and the heterocycle core has the ability of impart lateral and/or longitudinal dipoles. 7In particular 1,3 thiazoles derivatives show bond angles of 153° and 133°, depending on the substitution pattern, and a dipole moment of 1.6 D. 8 In addition, the presence of the electron-rich sulfur atom attains modifications on the ionization potential that could induce smectic mesophases. 9oreover, mesophase morphologies can be further tuned by replacement of a flexible non branched alkyl chain for a perfluorinated segment. 10The increased rigidity, linearity and low surface energy of the perfluorinated chain compared to the hydrocarbon one, settles particular properties modifications, as the fluorophobic effect, which reduces the miscibility of the fluorinated moieties with other sides of the molecule. 11Thus, fluoro substituents and perfluorochains have been incorporated to LC compounds leading to a variety of modifications on these substances behaviors, as broad mesomorphic ranges, different mesophase morphologies, lower melting points and transition temperatures as well as stabilization of preexisting mesophases, due to the combination of small size, intense polarity and high strength of the C-F bond. 10 Such attributes can be successfully comprised in the structure of mesogens and are of major significance in terms of primary structure property relationships, any more than crucial to the development of novel liquid crystal materials. 12For the thiazole building block showed in Figure 1, the general structure carries always on a flexible alkyl chain from one side of the molecule and a carboxylic group at the other side to be derivatized into aliphatic or aromatic esters and amides.Among the wide range of methodologies for preparation of thiazoline derivatives, 13 the one based on cyclization of nitriles with the natural amino acid L-cysteine was elected, 14,15 once it employs readily accessfull and low cost starting materials.Also, this method delivery the target precursor bearing the desirable carboxyl group mentioned above, which enables the possibility to attach a variety of substituents by means of esterification procedures employing different alcohols phenols. Thiazolines synthesis and their subsequent oxidation to heteroaromatic thiazole rings are an interesting way to prepare building block to be used in many branchs of the synthetic organic chemistry.As demonstrated in this work, a sequential oxidation of the thiazoline to thiazole ring leads to an enhancement of geometrical anisometry of the rigid core contributing for emergence of mesomorphic and photoluminescent properties.Thereby, we wish to report a simple and straightforward methodology for the synthesis of a new class of compounds derived from the thiazoline precursor using the chain elongation strategy as well as to investigate the liquid-crystalline behavior of the final thiazole esters. General structure of target thiazole esters is presented in Figure 1.Primitive core is formed by aromatic and thiazole ring connected by a single bond.Variable connection means the chemical communication between additional group on the right side and the primitive core intermediated by carboxyl group presented in the target esters.Thiazolines 6a-k and thiazoles 7a-k are composed of a flexible hydrogenated alkyl chain on the left side of Figure 1, except for those from 4-bromophenyl nitrile.On the right side of Figure 1, terminal segments connected by carboxyl group are composed of flexible alkyl chains (hydrogenated chain), (perfluoralkyl) alkyl chains (semifluorinated alkane) 16 and p-alkoxyphenyl chains.Figure 1 shows the general structure of the new thiazole esters synthesized in this work. | 2 |
97099960 | Synthesis The synthesis of key intermediate thiazoline carboxylic acids 4a-c is outlined in Scheme 1.The strategy applied here begins with the commercially available nitriles 1a and 1b, which were submitted to the alkylation reaction with 1-bromoctane under basic conditions, affording the alkylated nitriles 2a and 2b in almost quantitatively yields.From this point, in Scheme 1, 4-bromobenzonitrile (2c) was added to our plan of the synthesis of 4a-c.Next step nitriles 2a-c were submitted to cyclization reaction with amino acid L-cysteine (3) to generate the key intermediates thiazoline derivatives 4a-c.In general, the most common procedure for this reaction involves a system of water/ alcohol under buffer control by several days. 17In our hands the experimental condition describe above to yield the corresponding thiazoline carboxylic acids 4a-c gave very low yields of the described thiazoline derivatives.In order to achieve better results, we changed the initial protocol reaction to one that has been used by Loughlin et al.. 18 Under the new experimental conditions, we prepared the intermediate 4a-c in a good yield.Thus, exposing nitriles 2a-c to L-cysteine mediate by sodium bicarbonate, morpholine and reflux in an alcoholic solvent (ethanol or isopropanol), the cyclizated products 4a-c were afforded in excellent overall yields.This is an interesting and an alternative way to prepare thiazolines in a simple and almost inexpensive methodology. After accomplished successfully the synthesis of 4a-c, the esters formation was initiated to complete our synthetic plan.Esterification reactions with activation of acids by carbodiimides are probably the most versatile procedures for preparation of ester compounds. 19The chemical linkage between 4a-c and 5a-d to obtain the final thiazoline esters 6a-k was firstly attempted using the dicyclohexylcarbodiimide/4-N,N-dimethylaminopyridine (DCC/DMAP) protocol. 20However, due to the troublesome to remove the by-product urea, we changed DCC to 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDCI) to promote the ester ligation.Thus, thiazoline esters 6a-k were synthesized as outlined in Scheme 2, by activation of acids 4a-c with EDCI followed by the reaction with several alcohols 5a-d in dichloromethane and DMAP as a catalyst.Table 1 summarizes the results for the thiazoline esters 6a-k.It is noteworthy to mention that EDCI/DMAP couple worked successfully for a variety of chosen alcohols, such as alkyl and (perfluoralkyl)alkyl and phenols, delivering the intermediates compounds 6a-k to be transformed into LC in good yields by oxidation process. The 2,5-disubstituted thiazole core in the final compounds 7a-k was accomplished as described in Scheme 3. Several methods were evaluated to perform this transformation, such as reactions with 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ), 21 NiO 2 22 and MnO 2 . 23First attempts employing this later strategy resulted in poor yields of target final products, as well as a complex mixture of by-products detected by thin layer chromatography (TLC) analysis of crude reaction extract.In order to improve the obtention of these target mesogens, the oxidative dehydrogenation step was most conveniently performed using a mixture of bromotrichloromethane and 1,8-diazabicyclo[5.4.0]undec-7-ene (BrCCl 3 /DBU). 24In comparison to the ones mentioned above, this synthetic protocol is advantageous for its milder conditions and tolerating to a large variety of functional groups.Therefore, the bromination takes place first in 6a-k and then, the dehidrobromination in presence of DBU in dry DCM furnished the final products 7a-k in good to excellent yields (Table 2). 25 | 3 |
97099960 | General methods All starting materials were purchased from commercial suppliers (Sigma Aldrich Chemical Co., Acros Organics and ABCR Chemicals) and used without further purification.All reactions were carried out under a nitrogen atmosphere in oven-dried glassware with magnetic stirring.Solvents were dried, purified and degassed under classical methods.Solvents used in extraction and purification were distilled prior to use.TLC was performed using silica gel 60 F254 aluminum sheets and the visualization of the spots has been done under UV light (254 nm) or stained with iodine vapor.Products were purified by flash chromatography on silica gel 60 M, 230-400 mesh.Melting and mesophase transition temperatures and textures of the samples points were measured using an Olympus BX43 microscope equipped with a Mettler Toledo FP82HT Hot Stage FP90. 1 H ( 13 C) NMR spectra were recorded at 300 (75) MHz on a Varian Inova and 400 (100) MHz Bruker spectrometer using CDCl 3 as solvent.The 1 H and 13 constants J [Hz] were directly taken from the spectra and are not averaged.Splitting patterns are designated as s (singlet), d (doublet), t (triplet), q (quartet), m (multiplet) and br (broad).Low-resolution mass spectra were obtained with a Shimadzu GC-MS-QP5050 mass spectrometer interfaced with a Shimadzu GC-17A gas chromatograph equipped with a DB-17 MS capillary column.HRMS spectra were obtained from a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer equipped with an Infinity™ cell, a 7.0 Tesla superconducting magnet, an RF-only hexapole ion guide and an external electrospray ion source (off axis spray) and with ESI(+)-MS and tandem ESI(+)-MS/MS using a hybrid high-resolution and high accuracy MicroTOF-Q II mass spectrometer (Bruker Daltonics), or on a Micromass Q-TOFmicro instrument. General procedure for the synthesis of thiazolines 4a-c A solution of L-cysteine hidrochloride (60 mmol; 10.8 g), NaHCO 3 (60 mmol; 5.3g), the appropriate nitrile (20 mmol) in 85 mL of ethanol was refluxed for 30 min.After, the pH was adjusted to 8.0 by adding a few drops of morpholine, and the reflux was continued for additional 12 h.The ethanol was removed, the residue dissolved in distilled water and acidified to pH 1.5 by adding concentrated HCl.The product was extracted with CH 2 Cl 2 (3 × 50 mL), the organic layers where combined, dried over MgSO 4 and the solvent removed under vacuum.The products were obtained with satisfactory purity and were used in the next step without further purification. | 6 |
97099960 | General procedure for esterification of thiazolines 6a-k To a stirred solution of the corresponding thiazoline 4a-c (2.0 mmol) in dry CH 2 Cl 2 (8 mL) under N 2 atmosphere at room temperature, were added subsequently the corresponding alcohol (2.0 mmol) EDCI (2.0 mmol) and catalytic amount of DMAP.After 16 h, the organic phase was transferred to an extraction funnel, washed with saturated NaHCO 3 (2 × 10 mL), water (2 × 10 mL) and the organic layer was dried with Na 2 SO 4 .The solvent was evaporated and the remaining product was purified by chromatography (hexanes/AcOEt = 80:20). | 7 |
55209977 | The effect of biodiesel produced from waste cooking oil on the particulate emissions of a direct injection (DI) diesel engine was investigated experimentally and the results were compared with two diesel fuels, namely, an ultra low sulfur diesel fuel with less than 10-ppm-wt of sulfur (ULSD) and a low sulfur diesel fuel with 400-ppm-wt of sulfur (LSD). For each fuel, the number and mass based particle emissions, as well as the particle volatility, were evaluated and compared. The particulate mass emissions were measured with a tapered element oscillating balance (TEOM) and further divided into different size bins using a micro-orifice uniform deposition impactor (MOUDI). The particle number concentration and size distribution were measured with a scanning mobility particle sizer (SMPS). The size-segregated samples collected with the MOUDI were further analyzed with a thermogravimetric analyzer (TGA) to obtain the mass of volatile substances in each size bin. The SMPS was further connected in series with a thermodenuder (TD) to obtain the number concentration and size distribution of non-volatile particles, and hence the number concentration and size distribution of the volatile particles. The results indicate that the biodiesel could effectively reduce the particle mass and number concentrations, including the volatile substances, in all the measured size range, compared with LSD. Compared with ULSD, there is also a reduction in the particle mass and number concentrations, however, a higher concentration of volatile substances was found with the use of biodiesel, which should be a concern in the application of this fuel. | 1 |
55209977 | INTRODUCTION Diesel particulates are composed of soot aggregates and volatile substances which include hydrocarbons and sulfate.Volatile substances have complex composition, some of which are toxic and carcinogenic.Therefore, it is important to analyze the volatility of diesel particles because it is an indication of the toxicity of these particles (Giechaskiel et al., 2009;Chuang et al., 2010;Ning and Sioutas, 2010;Wu et al., 2010;Tsai et al., 2011).There are different methods for investigating particle volatility.Maricq et al. (2002) used a scanning mobility particle sizer (SMPS) and a thermal denuder (TD) to investigate the particulate emissions of a diesel engine fueled with a diesel fuel containing 350 ppmwt sulfur.They found that most of the nuclei mode particles could be adsorbed by the TD.Rönkkö et al. (2007) compared the particle number-size distribution using a nano-SMPS and a TD and found that the nucleation mode particles have a non-volatile core with volatile species condensed on it.Kwon et al. (2003) and Sakurai et al. (2003) investigated the volatility of diesel particles using a tandem differential mobility analyzer (TDMA) and found that the volatility was size-dependent.Filter-based methods have also been used to investigate the volatile substance in diesel particles.These methods include thermal-gravimetric analysis, thermal optical carbon analysis and Soxhlet extraction (Kerminen et al., 1997;Ning et al., 2004;Collura et al., 2005;Shen et al., 2009;Mustafi et al., 2010). Former investigations on particle volatile mainly focused on the effects of fuel sulfur content, which have been well reported (Maricq et al., 2002;Vaaraslahti et al., 2004;Ristovski et al., 2006;Rönkkö et al., 2007) and induced the tightening up of diesel sulfur content.In China, the national standard of diesel fuel follows the standard EN590.The limit of sulfur content in EN590 and its execution date in Europe and China are listed in Table 1.In China the current maximum sulfur content is limited to about 350 ppm-wt and will be further reduced, while in Europe, it has been limited to less than 10 ppm-wt.Over the past decade, using biodiesel as an alternate diesel fuel has drawn increasing interest due to its biodegradable and nontoxic properties and using biodiesel can significantly reduce particulate emissions and overall life-cycle CO 2 emission from the engine (Lapuerta et al., 2008).However, research on volatility of particles generated from the combustion of biodiesel, in particular biodiesel produced from waste cooking oil, is rare (Jung et al., 2006;Heikkilä et al., 2009;Surawski et al., 2011a, b). In this study, we investigated the effect of a biodiesel produced from waste cooking oil on the particle number/ mass-size distributions and the volatility of the particles in the exhaust of a diesel engine.We used a SMPS and a TD to investigate the number-size distributions of the volatile substances, and used a thermal-gravimetric analyzer to investigate the mass-size distributions of the volatile substances in the particles collected with a micro-orifice uniform deposition impactor (MOUDI), and the two results were compared.Investigation on both mass-based and number-based particle volatility is rarely reported in the literature.Two diesel fuels with different sulfur contents of 10-ppm-wt sulfur and 400-ppm-wt sulfur were used for comparison. | 2 |
55209977 | EXPERIMENTAL METHODS The study was performed on a naturally-aspirated, water cooled, 4-cylinder direct-injection diesel engine (ISUZU 4HF1).The specifications of the engine are shown in Table 2.The engine was connected to an eddy-current dynamometer and a control system was used for adjusting its speed and torque.The major properties of the three fuels are given in Table 3. ULSD is widely used in Europe while the properties of the LSD are similar to the diesel fuel available in China.The biodiesel used in this study was produced from waste cooking oil by Dynamic Progress Ltd. and its properties are in compliance with the standard EN14214. The schematic of the experimental system is shown in Moreover, for minimizing cross contamination of different fuels, the engine was allowed to operate with the new fuel for thirty minutes to clean the fuel system. Particle number concentration and size distribution was measured with a scanning mobility particle sizer (SMPS TSI Model 3934) for the size range of 10-486 nm.For each test condition, the SMPS scan was repeated 4 times.Before passing through the SMPS, the engine exhaust gas was diluted with a two-stage dilution unit (Dekati Ltd.).The transfer line from the exhaust to the diluter was heated at 170°C.The first stage was heated to keep the dilution air at 150°C to avoid condensation of volatile substances.The second diluter was directly connected to the first diluter and the diluted gas was maintained at about 25°C for direct coupling to the SMPS which counts particle concentrations on volume basis.The dilution ratio was determined from the measured CO 2 concentrations of background air, undiluted exhaust gas and diluted exhaust gas.CO 2 concentrations were measured with a non-dispersive infra-red analyzer (NDIR, CAI 300).The dilution ratio for the SMPS varied from 67.5 to 89.6, depending on the actual operating conditions.The dilution process will induce some variation of the particle size distribution in the exhaust gas, especially the nucleation mode particles which are sensitive to the dilution conditions (Shi and Harrison, 1999). Particulate mass concentration was measured with a tapered element oscillating microbalance (TEOM, Series 1105, Rupprecht & Patashnick Co., Inc.).The engine exhaust gas passed through the TEOM with the first stage dilution and the sampling temperature was around 52°C.The dilution ratio for the TEOM was one-eighth of that for the SMPS.Classified particulate samples were also collected using a micro-orifice uniform deposition impactor (MOUDI-110R, MSP Corporation) with 10 cut-point sizes of 10, 5.6, 3.2, 1.8, 1.0, 0.56, 0.32, 0.18, 0.1 and 0.056 μm for investigating the particle mass-size distributions.The sampling conditions are the same for the MOUDI and the TEOM, both have onestage dilution.47mm quartz filters (Whatman Corporation) were used as impaction substrate for the MOUDI to collect particulate samples.The quartz filters were prebaked at 500°C for 4 hours to remove any carbon contamination.Before and after sampling, the quartz filters in the MOUDI were allowed at least 24 hours equilibration in a controlled environment with a temperature of 21-22°C and relative humidity of 40-45% and then weighed with a microbalance (Mettler-Toledo XS105).Previous studies indicated that for motor vehicles, 80-90% of the particulate mass fraction is within the fine-particle size range (Kerminen et al., 1997;Chien et al., 2009;Zhang et al., 2009).Therefore, in this study, despite particles in all size bins were collected, only those less than 1.8 μm were weighed and analyzed.Two methods were used to investigate particle volatility, namely, a mass-based method and a number-based method.The former method involves the thermogravimetry analysis (TGA) of filter samples collected with the MOUDI.TGA was conducted using the Netzch-STA 449 TGA/DSC (thermogravimetric analyzer/differential scanning calorimetry) with Al 2 O 3 crucible.The particulate samples were firstly heated in an argon environment with a heating rate of 10°C per minute to 400°C, and then held at 400°C for 10 minutes.The mass loss in the argon environment was taken as the mass of the volatile substances.The remaining part was heated at an air environment with a heating rate of 10°C per minutes to 800°C.The mass loss at the air environment was taken as the mass of the non-volatile substances.Similar approach had been used by Boehman et al. (2005) and Mustafi et al. (2010) to distinguish the volatile and non-volatile fractions of diesel particles.The numberbased method was conducted by comparing the SMPS measurements with and without the Dekati thermo-denuder (TD).The TD consists of a heated section followed by an adsorber section where the vaporized compounds are adsorbed in activated charcoal.In this study, the particle number-size distributions obtained after the TD have been corrected for diffusion losses using the measured diesel particle number concentration with the TD set at 25°C (Surawski et al., 2011b). For the particle number and mass concentrations, the average values were presented.The standard errors were determined following the method of Kline and McClintock (1953).In order to ensure that the results are repeatable within the experimental uncertainties, for each test condition, the tests were repeated twice.In this study, the maximum standard errors are 2.5% for particle mass concentration using TEOM, 1.7% for particle number concentration, 2.3% for particle geometric mean diameter, and 4.5% for the volatile mass fraction determined with the TGA. | 3 |
55209977 | Particle Mass Concentrations and Size Distribution The total particulate mass concentration for each fuel and at each engine load was measured with the TEOM.The variation of brake specific particulate matter (BSPM) with engine load is shown in Fig. 2. For each fuel, the minimum BSPM appears at some intermediate engine loads which can be attributed to the lower brake thermal efficiency at low engine load and the higher particulate emissions at high engine load.At high engine load, the increase in fuel burned in the diffusion mode leads to a rapid increase in the particulate mass concentration in the engine exhaust gas and hence a corresponding increase in the BSPM. For the three fuels, the biodiesel and LSD generate the lowest and highest BSPM, respectively.The BSPM of biodiesel is 229.8 mg/kWh, on average of the five engine loads, which is 26.5% and 43.3% lower than BSPM of ULSD and LSD, respectively.The effectiveness of biodiesel on reducing particulate emission has been reported in the literature (Corporan et al., 2005;Tsolakis, 2006;Lapuerta et al., 2008).In general, there are three reasons leading to the lower particulate emission with biodiesel.Firstly, the advanced fuel ignition associated with biodiesel provides a longer time for soot oxidation.Secondly, the oxygen content of biodiesel enables more complete combustion and promotes the oxidation of the already formed soot.Thirdly, the absence of aromatics in biodiesel leads to a reduction in soot formation.Therefore, in this study, the engine fueled with biodiesel has lower particulate emission than fueled with the two diesel fuels.On the other hand, the lower aromatics content and the lower sulfur content are reasons for the lower particulate emission of ULSD, compared with LSD.Ullman et al. (1994) found a 3-5% particulate reduction for a 100 ppm-wt reduction in fuel sulfur on a heavy-duty diesel engine tested under a transient drive cycle. The particulate emission at the engine load of 0.7 MPa was chosen for the investigation of particulate mass-size distribution using the MOUDI.The BSPM at different size bins are shown in Fig. 3 while the mass median diameters (MMD) and their geometric standard deviations of the diesel particulate are listed in Table 4.For each fuel, the masssize distribution of the particles exhibits a peak BSPM at the size bin of 100-180 nm.The brake specific emissions of PM 1.8 are 198.8,399.6 and 576.4 mg/kWh for the biodiesel, ULSD and LSD, respectively.Effect of the biodiesel on reducing particulate emission in comparison with the ULSD and LSD, is in line with results obtained with the TEOM.As shown in Fig. 3, biodiesel could reduce BSPM in all the size bins, while the MMD of biodiesel particles is less than those of the ULSD and LSD, which indicates that the biodiesel particles contain a larger proportion of smallsize particles and the reduction on particulate emission arises from the reduction of the large-size particles.The same reasons which cause a larger reduction of particulate emissions with biodiesel, compared with the two diesel fuels, also lead to a larger reduction in particle MMD (Mathis et al., 2005;Tsolakis, 2006).Moreover, the reduction in particulate mass concentration may also suppress particle coagulation and hence reduce the MMD. | 4 |
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