Aim In the present study a RP-HPLC method was developed and validated toinvestigate the stability of baicalin aqueous solution. Methods The influences of temperature and pHon the stability of baicalin aqueous solution...Aim In the present study a RP-HPLC method was developed and validated toinvestigate the stability of baicalin aqueous solution. Methods The influences of temperature and pHon the stability of baicalin aqueous solution were investigated by classic homoiothermicacceleration test, and the pH for the most stable solution was determined. Results The time whenbaicalin suffered 10% loss was found to be 18.1 h, and the degradation activation energy of baicalinwas 79.1 kJ·moL^(-1) . The pH at which baicalin is most stable is 4.28. Conclusion The temperatureshould be kept at a lower level and the pH should be adjusted to near that for the most stablesolution in the production of baicalin preparations.展开更多
Objective: To establish a new assay for platelet-activating factor (PAF), to compare it with bio-assay; and to discuss its significance in some elderly people diseases such as cerebral infarction and coronary heart di...Objective: To establish a new assay for platelet-activating factor (PAF), to compare it with bio-assay; and to discuss its significance in some elderly people diseases such as cerebral infarction and coronary heart disease. Methods: To measure PAF levels in 100 controls, 23 elderly patients with cerebral infarction and 65 cases with coronary heart disease by reversed phase high-performance liquid chromatographic technique (rHPLC). Results:rHPLC is more convenient, sensitive,specific, and less confusing, compared with bio-assay. The level of plasma PAF in patients with cerebral infarction was higher than that in the controls (P<0.01), and in patients with coronary heart disease. Conclusion: Detection of PAF with rHPLC is more reliable and more accurate. The new assay has important significance in PAF research.展开更多
the effects of reduction procedure, reaction temperature andcomposition of feed gas on the activity of a CuO-ZnO-Al_2O_3 catalystfor liquid phase methanol synthesis were studied. An optimizedprocedure different from c...the effects of reduction procedure, reaction temperature andcomposition of feed gas on the activity of a CuO-ZnO-Al_2O_3 catalystfor liquid phase methanol synthesis were studied. An optimizedprocedure different from conventional ones was developed to obtainhigher activity and better stability of the catalyst. Both CO andCO_2 in the feed gas were found to be necessary to maintain theactivity of catalyst in the synthesis process. Reaction temperaturewas limited up to 523 K, otherwise the catalyst will be deactivatedrapidly.展开更多
A Glycoside hydrolase （GH） typically contains one catalytic module and varied non-catalytic regions （NCRs）. However, effects of the NCRs to the catalytic modules remain mostly unclear except the carbohydrate-bindi...A Glycoside hydrolase （GH） typically contains one catalytic module and varied non-catalytic regions （NCRs）. However, effects of the NCRs to the catalytic modules remain mostly unclear except the carbohydrate-binding modules （CBMs）. AgaG4 is a GH16 endo-β-agarase of the agarolytic marine bacterium Flammeovirga sp. MY04. The enzyme consists of an extra sugar-binding peptide within the catalytic module, with no predictable CBMs but function-unknown sequences in the NCR, which is a new characteristic of agarase sequences. In this study, we deleted the NCR sequence, a 140-amino acid peptide at the C-terminus and expressed the truncated gene, agaG4-T140, in Escherichia coli. After purification and refolding, the trtmcated agarase rAgaG4-T140 retained the same catalytic temperature and pH value as rAgaG4. Using combined fluorescent labeling, HPLC and MS/MS techniques, we identified the end-products of agarose degradation by rAgaG4-T140 as neoagarotetraose and neoagarohexaose, with a final molar ratio of 1.53：1 and a conversion ratio of approximately 70%, which were similar to those of rAgaG4. However, the truncated agarase rAgaG4-T140 markedly decreased in protein solubility by 15 times and increased in enzymatic activities by 35 times. The oligosaccharide production of rAgaG4-T140 was approximately 25 times the weight of that produced by equimolar rAgaG4. This study provides some insights into the influences of NCR on the biochemical characteristics of agarase AgaG4 and implies some new strategies to improve the properties of a GH enzyme.展开更多
The effect of catalyst properties on residue oil hydroconversion was studied at moderate operating conditions(at a temperature of 400 ℃, an initial hydrogen pressure of 10 MPa, and a reaction time of 4 h) in a batch ...The effect of catalyst properties on residue oil hydroconversion was studied at moderate operating conditions(at a temperature of 400 ℃, an initial hydrogen pressure of 10 MPa, and a reaction time of 4 h) in a batch mode slurry phase with different catalyst samples. The results showed that the catalyst acidity had a good effect on residue conversion and MCR(micro carbon residue) conversion but brought about higher coke yield. Residue conversion was thermally induced but the catalyst acidity changed its conversion route. A catalyst with higher metal loading, higher hydrogenation activity and appropriate pore size had higher sulfur and metal removal rate, higher MCR conversion and also a lower coke formation. The activity of spent commercial catalyst AS1 and DS1 was slightly lower than the corresponding fresh ones but was still high enough for residue oil hydroconversion. It assumes that the role of the catalyst is to activate hydrogen species toward reaction with an aromatic carbon radical to yield a cyclohexadienyl type intermediate which will turn into liquid and also to absorb the mesophase which can easily aggregate to form coke.展开更多
Biological treatment efficiency of six pharmaceutical compounds （acetazolamide, metronidazole, opipramol, piracetam, salicylamide and tinidazole） was evaluated using lab-scale Sequencing Batch Reactor （SBR）. Compa...Biological treatment efficiency of six pharmaceutical compounds （acetazolamide, metronidazole, opipramol, piracetam, salicylamide and tinidazole） was evaluated using lab-scale Sequencing Batch Reactor （SBR）. Comparative biological degradation processes of two types of activated sludge from municipal and pharmaceutical industry sewage treatment plants were examined. Three different organic loadings （0.05 g COD/g MLSS.d, 0.1 g COD/g MLSS.d and 0.2 g COD/g MLSS-d） and reaction time on the efficiency of Active Pharmaceutical Ingredient （API） decomposition were examined. Chemical oxygen demand, non-purgeable organic carbon as well as ammonium nitrogen contents were monitored by standard methods. Percentage of API decomposition was analysed by High Performance Liquid Chromatography （HPLC）. The overall API removal efficiency was strictly dependent on the type of activated sludge origin. The main biodegradation products were identified using HPLC-MS,1H NMR and 13C NMR methods as e.g. （{4-[3-（5H-dibenzo[b,f]azepin-5-yl]piperazin-l-yl}methanamine） and （2-amino-1,3,4-thiadiazol-5-sulfonamide） for opipramol and acetazolamide respectively.展开更多
文摘Aim In the present study a RP-HPLC method was developed and validated toinvestigate the stability of baicalin aqueous solution. Methods The influences of temperature and pHon the stability of baicalin aqueous solution were investigated by classic homoiothermicacceleration test, and the pH for the most stable solution was determined. Results The time whenbaicalin suffered 10% loss was found to be 18.1 h, and the degradation activation energy of baicalinwas 79.1 kJ·moL^(-1) . The pH at which baicalin is most stable is 4.28. Conclusion The temperatureshould be kept at a lower level and the pH should be adjusted to near that for the most stablesolution in the production of baicalin preparations.
文摘Objective: To establish a new assay for platelet-activating factor (PAF), to compare it with bio-assay; and to discuss its significance in some elderly people diseases such as cerebral infarction and coronary heart disease. Methods: To measure PAF levels in 100 controls, 23 elderly patients with cerebral infarction and 65 cases with coronary heart disease by reversed phase high-performance liquid chromatographic technique (rHPLC). Results:rHPLC is more convenient, sensitive,specific, and less confusing, compared with bio-assay. The level of plasma PAF in patients with cerebral infarction was higher than that in the controls (P<0.01), and in patients with coronary heart disease. Conclusion: Detection of PAF with rHPLC is more reliable and more accurate. The new assay has important significance in PAF research.
基金Work performed while the authors were at the Laboratory for Catalysis and Chemical Reaction Engineering, National Institute of Chemistry, Slovenia, and supported by the Ministry of Science and Technology of Slovenia (No. J2-0783).
文摘the effects of reduction procedure, reaction temperature andcomposition of feed gas on the activity of a CuO-ZnO-Al_2O_3 catalystfor liquid phase methanol synthesis were studied. An optimizedprocedure different from conventional ones was developed to obtainhigher activity and better stability of the catalyst. Both CO andCO_2 in the feed gas were found to be necessary to maintain theactivity of catalyst in the synthesis process. Reaction temperaturewas limited up to 523 K, otherwise the catalyst will be deactivatedrapidly.
基金financially supported by the Open Research Fund Program of Shandong Provincial Key Laboratory of Glycoscience&Glycotechnology(Ocean University of China)KLGG(OUC)201301the National Natural Science Foundation of China Grants 31300664 and 31130004the State Key Laboratory of Microbial Technology Grant(Shandong University)M2013-11
文摘A Glycoside hydrolase （GH） typically contains one catalytic module and varied non-catalytic regions （NCRs）. However, effects of the NCRs to the catalytic modules remain mostly unclear except the carbohydrate-binding modules （CBMs）. AgaG4 is a GH16 endo-β-agarase of the agarolytic marine bacterium Flammeovirga sp. MY04. The enzyme consists of an extra sugar-binding peptide within the catalytic module, with no predictable CBMs but function-unknown sequences in the NCR, which is a new characteristic of agarase sequences. In this study, we deleted the NCR sequence, a 140-amino acid peptide at the C-terminus and expressed the truncated gene, agaG4-T140, in Escherichia coli. After purification and refolding, the trtmcated agarase rAgaG4-T140 retained the same catalytic temperature and pH value as rAgaG4. Using combined fluorescent labeling, HPLC and MS/MS techniques, we identified the end-products of agarose degradation by rAgaG4-T140 as neoagarotetraose and neoagarohexaose, with a final molar ratio of 1.53：1 and a conversion ratio of approximately 70%, which were similar to those of rAgaG4. However, the truncated agarase rAgaG4-T140 markedly decreased in protein solubility by 15 times and increased in enzymatic activities by 35 times. The oligosaccharide production of rAgaG4-T140 was approximately 25 times the weight of that produced by equimolar rAgaG4. This study provides some insights into the influences of NCR on the biochemical characteristics of agarase AgaG4 and implies some new strategies to improve the properties of a GH enzyme.
文摘The effect of catalyst properties on residue oil hydroconversion was studied at moderate operating conditions(at a temperature of 400 ℃, an initial hydrogen pressure of 10 MPa, and a reaction time of 4 h) in a batch mode slurry phase with different catalyst samples. The results showed that the catalyst acidity had a good effect on residue conversion and MCR(micro carbon residue) conversion but brought about higher coke yield. Residue conversion was thermally induced but the catalyst acidity changed its conversion route. A catalyst with higher metal loading, higher hydrogenation activity and appropriate pore size had higher sulfur and metal removal rate, higher MCR conversion and also a lower coke formation. The activity of spent commercial catalyst AS1 and DS1 was slightly lower than the corresponding fresh ones but was still high enough for residue oil hydroconversion. It assumes that the role of the catalyst is to activate hydrogen species toward reaction with an aromatic carbon radical to yield a cyclohexadienyl type intermediate which will turn into liquid and also to absorb the mesophase which can easily aggregate to form coke.
文摘Biological treatment efficiency of six pharmaceutical compounds （acetazolamide, metronidazole, opipramol, piracetam, salicylamide and tinidazole） was evaluated using lab-scale Sequencing Batch Reactor （SBR）. Comparative biological degradation processes of two types of activated sludge from municipal and pharmaceutical industry sewage treatment plants were examined. Three different organic loadings （0.05 g COD/g MLSS.d, 0.1 g COD/g MLSS.d and 0.2 g COD/g MLSS-d） and reaction time on the efficiency of Active Pharmaceutical Ingredient （API） decomposition were examined. Chemical oxygen demand, non-purgeable organic carbon as well as ammonium nitrogen contents were monitored by standard methods. Percentage of API decomposition was analysed by High Performance Liquid Chromatography （HPLC）. The overall API removal efficiency was strictly dependent on the type of activated sludge origin. The main biodegradation products were identified using HPLC-MS,1H NMR and 13C NMR methods as e.g. （{4-[3-（5H-dibenzo[b,f]azepin-5-yl]piperazin-l-yl}methanamine） and （2-amino-1,3,4-thiadiazol-5-sulfonamide） for opipramol and acetazolamide respectively.
