A sensitive and specific high performance liquid chromatography （HPLC） method was developed and validated for the simultaneous determination of metformin hydrochloride （HCI） in human plasma. The HPLC method consis...A sensitive and specific high performance liquid chromatography （HPLC） method was developed and validated for the simultaneous determination of metformin hydrochloride （HCI） in human plasma. The HPLC method consists of isocratic eluation with a mixture of 60% buffer （10 mM sodium dihyrogenphosphate-10 mM sodium dodecyl sulphate） and 40% acetonitrile with final pH 7.0 with flow rate of 1.0 mL/min on a Kromasil~ Akzo Nobel RP-18 （4.6 mm ID ~ 250 mm, 5 ~tm） column at an ambient temperature. Photo diode array detection was performed in program mode at 234 rim. The analyte and diazepam as internal standard （IS） were extracted from plasma using 10% trichloroacetic acid. The assay was linear over the therapeutic concentration range of 20-2,500 ng/mL for metformin HCI with correlation coefficient of r = 0.9999. Limit of quantitation was 20 ng/mL. The results obtained for intraJinter day accuracy and precision complied very well with the generally accepted criteria for bio-analytical assay. The method was applied to bioequivalence （BE） study of metformin HCI in healthy Indonesian volunteers after treatment with 750 mg XR metformin HCI. This BE study shows that the two formulations are equivalent so that they were therapeutically interchangeable for each other.展开更多
‘Coherent control of high-harmonic generation in a two-color field’ has been widely concerned. Using split-operator algorithm, we have calculated the high-harmonic generation for helium ion He+ in a two-color field ...‘Coherent control of high-harmonic generation in a two-color field’ has been widely concerned. Using split-operator algorithm, we have calculated the high-harmonic generation for helium ion He+ in a two-color field which is composed of a driving field and a weak subsidiary high frequency field (Is = I0/100, (ω,13ω),...(ω, 120ω)) and found that such a field can produce much higher harmonic intensity, typically increasing the harmonics corresponding to the incident frequency of the subsidiary field. The different effects coming from the different subsidiary fields are calculated and analyzed. It is indicated that one of the important underlying mechanisms is high frequency photon induced radiation.展开更多
1,3-Propanediol （PDO） is an important bulk industrial material. It can be produced by microbial fermentation. In this study, the microbial flora of mangrove sediment was screened to identify strains with high produc...1,3-Propanediol （PDO） is an important bulk industrial material. It can be produced by microbial fermentation. In this study, the microbial flora of mangrove sediment was screened to identify strains with high production of PDO by fermentation of glycerol. The PDO productivities of the isolated strains were tested, and the strain with highest PDO productivity was characterized using the API20E and 16-s rRNA sequence analysis. The physiological and phylogenetic analysis indicated that the strain was closed related to K. pneumoniae species and was named as K. pneumoniae HSL4. The structure of the dha cluster which was responsible for the biosynthesis of PDO was analyzed. It is observed that K. pneumoniae HSL4 was tolerant to salt and partly tolerant to acetate and lactate, which will favor industrial applications. Fed-batch fermentation experiments revealed K. pneumoniae HSL4 exhibited an excellent ability to produce PDO with high concentration （80.08 g L^-1）, productivity （2.22 g L^-1h^-1） and conversion （0.435 g g^-1 or 0.53 mol mol^-1）. The metabolic flux profile illuminated that glycerol was consumed rapidly and PDO was accumulated quickly to a high level during the exponential growth phase. This study provided important information for further fermentation and metabolic engineering of PDO production by K. pneumoniae HSL4.展开更多
文摘A sensitive and specific high performance liquid chromatography （HPLC） method was developed and validated for the simultaneous determination of metformin hydrochloride （HCI） in human plasma. The HPLC method consists of isocratic eluation with a mixture of 60% buffer （10 mM sodium dihyrogenphosphate-10 mM sodium dodecyl sulphate） and 40% acetonitrile with final pH 7.0 with flow rate of 1.0 mL/min on a Kromasil~ Akzo Nobel RP-18 （4.6 mm ID ~ 250 mm, 5 ~tm） column at an ambient temperature. Photo diode array detection was performed in program mode at 234 rim. The analyte and diazepam as internal standard （IS） were extracted from plasma using 10% trichloroacetic acid. The assay was linear over the therapeutic concentration range of 20-2,500 ng/mL for metformin HCI with correlation coefficient of r = 0.9999. Limit of quantitation was 20 ng/mL. The results obtained for intraJinter day accuracy and precision complied very well with the generally accepted criteria for bio-analytical assay. The method was applied to bioequivalence （BE） study of metformin HCI in healthy Indonesian volunteers after treatment with 750 mg XR metformin HCI. This BE study shows that the two formulations are equivalent so that they were therapeutically interchangeable for each other.
文摘‘Coherent control of high-harmonic generation in a two-color field’ has been widely concerned. Using split-operator algorithm, we have calculated the high-harmonic generation for helium ion He+ in a two-color field which is composed of a driving field and a weak subsidiary high frequency field (Is = I0/100, (ω,13ω),...(ω, 120ω)) and found that such a field can produce much higher harmonic intensity, typically increasing the harmonics corresponding to the incident frequency of the subsidiary field. The different effects coming from the different subsidiary fields are calculated and analyzed. It is indicated that one of the important underlying mechanisms is high frequency photon induced radiation.
基金supported by the Scientific Research Project of the Marine Public Welfare Industry of China (201205020-4)Administration of Ocean and Fisheries of Guangdong Province (GD2012-D01-002)
文摘1,3-Propanediol （PDO） is an important bulk industrial material. It can be produced by microbial fermentation. In this study, the microbial flora of mangrove sediment was screened to identify strains with high production of PDO by fermentation of glycerol. The PDO productivities of the isolated strains were tested, and the strain with highest PDO productivity was characterized using the API20E and 16-s rRNA sequence analysis. The physiological and phylogenetic analysis indicated that the strain was closed related to K. pneumoniae species and was named as K. pneumoniae HSL4. The structure of the dha cluster which was responsible for the biosynthesis of PDO was analyzed. It is observed that K. pneumoniae HSL4 was tolerant to salt and partly tolerant to acetate and lactate, which will favor industrial applications. Fed-batch fermentation experiments revealed K. pneumoniae HSL4 exhibited an excellent ability to produce PDO with high concentration （80.08 g L^-1）, productivity （2.22 g L^-1h^-1） and conversion （0.435 g g^-1 or 0.53 mol mol^-1）. The metabolic flux profile illuminated that glycerol was consumed rapidly and PDO was accumulated quickly to a high level during the exponential growth phase. This study provided important information for further fermentation and metabolic engineering of PDO production by K. pneumoniae HSL4.
