[Objectives]This study aimed to establish a quality evaluation method for Herba Cistanche based on the HPLC characteristic chromatograms of the phenylethanoid glycosides and iridoid glycosides,and compare the HPLC cha...[Objectives]This study aimed to establish a quality evaluation method for Herba Cistanche based on the HPLC characteristic chromatograms of the phenylethanoid glycosides and iridoid glycosides,and compare the HPLC characteristic chromatograms of different origins of Herba Cistanche.[Methods]The chromatographic conditions used were as follows:column,Agilent ZORBAX Eclipse Plus C18 column(4.6 mm×250 mm,5μm);gradient elution,acetonitrile-0.1%phosphoric acid aqueous solution;flow rate,1.0 mL/min;detection wavelength,240 nm;column temperature,30℃.[Results]Cistanche tubulosa(Schenk)Wight showed 9 characteristic peaks,Cistanche deserticola Y.C.Ma showed 10 characteristic peaks,Cistanche salsa(C.A.Mey.)G.Beck showed 7 characteristic peaks,and Cistanche sinensis G.Beck showed 4 characteristic peaks.Peak 6 was echinacoside,peak 7 was verbascoside,peak 8 was tubuloside A,peak 9 was isoacteoside and peak 10 was cistanoside A.The characteristic chromatograms of the four different origins of Herba Cistanche were significantly different.[Conclusions]This characteristic chromatogram method has good reproducibility and can be used to distinguish 4 different origins of Herba Cistanche,C.deserticola Y.C.Ma,C.tubulosa(Schenk)Wight,C.sinensis G.Beck and C.salsa(C.A.Mey.)G.Beck.展开更多
[Objectives]This study was conducted to establish characteristic chromatograms of of the volatile oil of Xinyi Biyan Pills by gas chromatography,discover possible problems in the production processes of different manu...[Objectives]This study was conducted to establish characteristic chromatograms of of the volatile oil of Xinyi Biyan Pills by gas chromatography,discover possible problems in the production processes of different manufacturers,and further improve the quality control methods.[Methods]The volatile oil in samples was extracted and tested by gas chromatography to collect chromatograms,which were analyze and evaluated by the similarity evaluation software of chromatographic fingerprints of traditional Chinese medicine.[Results]Nineteen common peaks were calibrated in the characteristic chromatograms;and the characteristic chromatograms of samples produced by different manufacturers were obviously different.[Conclusions]Controlling the volatile components in Xinyi Biyan Pills by the established characteristic chromatograms of GC is accurate and feasible,and can be used as a quality control method for Xinyi Biyan Pills.展开更多
[Objectives]To establish a HPLC characteristic spectrum of honeysuckle stem formula granules,and to evaluate the quality consistency based on the standard decoction.[Methods]Using Agilent ZORBAX SB-C_(18)(5μm,250 mm&...[Objectives]To establish a HPLC characteristic spectrum of honeysuckle stem formula granules,and to evaluate the quality consistency based on the standard decoction.[Methods]Using Agilent ZORBAX SB-C_(18)(5μm,250 mm×4.6 mm)chromatographic column;gradient elution with acetonitrile-0.4%phosphoric acid solution(0.2:99.8,V/V),column temperature at 25℃;detection wavelength at 236 nm;flow rate 1.0 mL/min;using"Similarity Evaluation System for Chromatographic Fingerprint of Traditional Chinese Medicine",to evaluate the similarity of the characteristic chromatogram of crude drug,standard decoction and formula granules of honeysuckle stem.[Results]The similarity of characteristic chromatogram was higher than 0.94,and 6 components were identified from 10 characteristic peaks.[Conclusions]The established method can more comprehensively reflect the overall appearance of the chemical substances in the honeysuckle stem and the transmission law,and can provide an experimental basis for the consistency of the quality of the honeysuckle stem formula granules.展开更多
By gas chromatogram, six crude oils fingerprinting distributed in four oilfields and four oil platforms were analyzed and the corre- sponding normal paraffin hydrocarbon ( including pristane and phytane) concentrati...By gas chromatogram, six crude oils fingerprinting distributed in four oilfields and four oil platforms were analyzed and the corre- sponding normal paraffin hydrocarbon ( including pristane and phytane) concentration was obtained by the internal standard methed. The normal paraffin hydrocarbon distribution patterns of six crude oils were built and compared. The cluster analysis on the normal paraffin hydrocarbon concentration was conducted for classification and some ratios of oils were used for oils comparison. The results indicated: there was a clear difference within different crude oils in different oil fields and a small difference between the crude oils in the same oil platform. The normal paraffin hydrocarbon distribution pattern and ratios, as well as the cluster analysis on the nomad paraffin hydrocarbon concentration can have a better differentiation result for the crude oils with small difference than the original gas chromatogram.展开更多
DNA barcoding and HPLC specific chromatogram were used to identify three kinds of Plumeria flowers respectively. DNAs extracted from the three Plumeria species were amplified by PCR with universal primers, and the psb...DNA barcoding and HPLC specific chromatogram were used to identify three kinds of Plumeria flowers respectively. DNAs extracted from the three Plumeria species were amplified by PCR with universal primers, and the psbA-trnH region was selected. All the amplified products were sequenced and the results were analyzed by MEGA 5.0. Chemometric methods including principal components analysis and hierarchical clustering analysis were conducted on the SAS 9.0 software to demonstrate the variability among samples. In conclusion, the psbA-trnH of all samples were successfully amplified from total DNA and sequenced. These three varieties of Plumeria can be differentiated by the psbA-trnH region and clustered into three groups respectively through building neighbor joining tree, which conformed to their germplasm origins. However, it was hard to distinguish them by HPLC specific chromatograms combined with chemometrics analysis. These indicated that DNA barcoding was a promising and reliable tool for the identification of three kinds of Plumeria flowers compared to HPLC specific chromatogram generally used. It could be treated as a powerful complementary method for traditional authentication, especially for those varieties which are difficult to be identified by conventional chromatography.展开更多
Selective cerebral deep hypothermia and blood flow occlusion can enhance brain tolerance to ischemia and hypoxia and reduce cardiopulmonary complications in monkeys. Excitotoxicity induced by the release of a large am...Selective cerebral deep hypothermia and blood flow occlusion can enhance brain tolerance to ischemia and hypoxia and reduce cardiopulmonary complications in monkeys. Excitotoxicity induced by the release of a large amount of excitatory amino acids after cerebral ischemia is the major mechanism underlying ischemic brain injury and nerve cell death. In the present study, we used selective cerebral deep hypothermia and blood flow occlusion to block the bilateral common carotid arteries and/or bilateral vertebral arteries in rhesus monkey, followed by reperfusion using Ringer's solution at 4~C. Microdialysis and transmission electron microscope results showed that selective cerebral deep hypothermia and blood flow occlusion inhibited the release of glutamic acid into the extracellular fluid in the brain frontal lobe and relieved pathological injury in terms of the ultrastructure of brain tissues after severe cerebral ischemia. These findings indicate that cerebral deep hypothermia and blood flow occlusion can inhibit cytotoxic effects and attenuate ischemic/ hypoxic brain injury through decreasing the release of excitatory amino acids, such as glutamic acid.展开更多
A novel artificial site specific cleavage reagent, with peptide nucleic acid (PNA) as sequence-recognizing moiety and cerium (IV) ions as “scissors” for cleaving target DNA, was synthesized. Subsequently, it was...A novel artificial site specific cleavage reagent, with peptide nucleic acid (PNA) as sequence-recognizing moiety and cerium (IV) ions as “scissors” for cleaving target DNA, was synthesized. Subsequently, it was employed in the cleavage of target 26-mer single-stranded DNA (ssDNA), which has 10-mer sequence complementary with PNA recognizer in the hybrids, under physiological conditions. Reversed-phase high-performance liquid chromatogram (RPHPLC) experiments indicated that the artificial site specific cleavage reagent could cleave the target DNA specifically.展开更多
[Objectives] To establish fingerprint chromatogram of Tetracera asiatica and provide basis for controlling and assessing the quality of Tetracera asiatica.[Methods] The high-performance liquid chromatography( HPLC) me...[Objectives] To establish fingerprint chromatogram of Tetracera asiatica and provide basis for controlling and assessing the quality of Tetracera asiatica.[Methods] The high-performance liquid chromatography( HPLC) method was used. Phenomenex C18( 5 μm,4. 6 ×250 mm),acetonitrile-0. 1% phosphoric acid water,gradient elution,flow rate 1 m L/min,detection wavelength 214 nm,and column temperature 25 ℃. The fingerprint chromatogram of 10 batches of samples of Tetracera asiatica was determined for similarity comparison. [Results] It established HPLC fingerprint chromatogram of Tetracera asiatica produced in Guangxi,determined a total of 13 common fingerprint peaks. The similarity of 10 batches of Tetracera asiatica was > 0. 9.[Conclusions] The method is rapid and accurate and can provide references for assessing the quality of Tetracera asiatica.展开更多
[Objectives]This study aimed to establish HPLC chromatograms of decoction pieces,standard decoction and formula granules of Spica Prunellae.[Methods]The chromatographic conditions were as follows:column,SHISEIDO CAPCE...[Objectives]This study aimed to establish HPLC chromatograms of decoction pieces,standard decoction and formula granules of Spica Prunellae.[Methods]The chromatographic conditions were as follows:column,SHISEIDO CAPCELL PAK C18 MGII column(4.6 mm×250 mm,5μm);mobile phase,acetonitrile-0.1%phosphoric acid;gradient elution;detection wavelength,280 nm;flow rate,1.0 mL/min;and column temperature,30℃.The correlation between the decoction pieces,standard decoction and formula granules of Spica Prunellae was analyzed by specific chromatograms.[Results]The fingerprint chromatograms of decoction pieces,standard decoction and formula granules of Spica Prunellae showed five common peaks,with good correlation.Among the five common peaks,four of them were tanshinol,protocatechuic acid,caffeic acid and rosmarinic acid.[Conclusions]The main chemical constituents of decoction pieces,standard decoction and formula granules of Spica Prunellae are basically the same.The HPLC specific chromatogram established can be used for the quality control of Spica Prunellae formula granules.展开更多
[Objectives] To study the typical HPLC chromatogram of petroleum ether in Abutilon indicum (L.) Sweet from different habitats, in order to provide experimental basis for the quality control of A. indicum and the spect...[Objectives] To study the typical HPLC chromatogram of petroleum ether in Abutilon indicum (L.) Sweet from different habitats, in order to provide experimental basis for the quality control of A. indicum and the spectrum-efficacy relationship of petroleum ether.[Methods] The HPLC chromatogram of petroleum ether was obtained using Agilent SB-C 18 (4.6 mm×250 mm, 5 μm) and acetine-0.1% phosphoric acid solution for gradient elution at temperature of 30 ℃, flow rate of 1.0 mL/min and detection wavelength of 205 nm.[Results] The typical HPLC chromatogram of petroleum ether in A. indicum was preliminarily established, with 12 characteristic peaks. It was verified by A. indicum from different habitats, characterized by reproducibility and stability.[Conclusions] Typical HPLC chromatogram provides a stable new method for the quality control of petroleum ether in A. indicum . This study provides experimental basis for further study on the medicinal parts of A. indicum .展开更多
A defect of chromatogram in a 35kV oil-immersed three-phase one-piece electric reactor in a 500kV substation。The initial analysis suggests that the defect is caused by the loose connection of the iron core magnet shi...A defect of chromatogram in a 35kV oil-immersed three-phase one-piece electric reactor in a 500kV substation。The initial analysis suggests that the defect is caused by the loose connection of the iron core magnet shield (magnet shield layer of iron core or earthling top). Examination of winding DC resistance, DGA and other relevant examinations were carried out to investigate the defect reasons., which is demonstrated by the dismantlement. In-depth study is taken and corresponding prevention measures are put forward in the paper.展开更多
Ⅰ. INTRODUCTION In the last few years, much effort has been devoted to developing the expert system for liquid chromatography (ESLC). In our previous papers, a strategy for the development of ESLC was established. Es...Ⅰ. INTRODUCTION In the last few years, much effort has been devoted to developing the expert system for liquid chromatography (ESLC). In our previous papers, a strategy for the development of ESLC was established. Establishment of a chromatogram base is one of the most important aspects in developing ESLC. Due to the fact that one of the most time-consuming and often frustrating jobs in chromatographic lab is to develop LC method for a展开更多
The effect of copper concentration on the performance of the catalytic reaction between silicon and methyl chloride was investigated using online gas chromatogram. The catalyst concentration greatly influences various...The effect of copper concentration on the performance of the catalytic reaction between silicon and methyl chloride was investigated using online gas chromatogram. The catalyst concentration greatly influences various aspects of the direct organosilane synthesis process, including the reaction rate, the selec- tivity, and the silicon conversion. The reaction activity and the silicon conversion increase as the catalyst concentration increases. However, the reaction selectivity decreases for the catalyst concentrations more .than 9 wt.%. The cross-sections of deactivated contact mass particles were observed by optical microscopy and analyzed by scanning electron microscope combined with energy dispersive X-ray detector (SEM-EDX) The observations showed that a textured substance formed on the original flat surface of the silicon particles after deactivation with copper only in a shallow surface layer of the contact mass. This indicates that the copper diffusion is the rate limiting step which causes the reaction deactivation.展开更多
Large size self-sustained film with considerable thickness ranging from 30 to 500 μm was prepared with sol-gel method by using dimethyldiethoxysilane/tetraethoxysilane composite alkoxide as precursor. The film exhibi...Large size self-sustained film with considerable thickness ranging from 30 to 500 μm was prepared with sol-gel method by using dimethyldiethoxysilane/tetraethoxysilane composite alkoxide as precursor. The film exhibits good plasticity as well. Various factors that may influence the film properties were investigated. IR and AFM techniques were adopted to study the film structure and surface morphology. Gas chromatogram/mass spectrum technique was also adopted to characterize the network structure of the material through identification of different polymers formed during hydrolysis and condensation course.展开更多
基金Nanning Excellent Young Scientist Program(RC20180206).
文摘[Objectives]This study aimed to establish a quality evaluation method for Herba Cistanche based on the HPLC characteristic chromatograms of the phenylethanoid glycosides and iridoid glycosides,and compare the HPLC characteristic chromatograms of different origins of Herba Cistanche.[Methods]The chromatographic conditions used were as follows:column,Agilent ZORBAX Eclipse Plus C18 column(4.6 mm×250 mm,5μm);gradient elution,acetonitrile-0.1%phosphoric acid aqueous solution;flow rate,1.0 mL/min;detection wavelength,240 nm;column temperature,30℃.[Results]Cistanche tubulosa(Schenk)Wight showed 9 characteristic peaks,Cistanche deserticola Y.C.Ma showed 10 characteristic peaks,Cistanche salsa(C.A.Mey.)G.Beck showed 7 characteristic peaks,and Cistanche sinensis G.Beck showed 4 characteristic peaks.Peak 6 was echinacoside,peak 7 was verbascoside,peak 8 was tubuloside A,peak 9 was isoacteoside and peak 10 was cistanoside A.The characteristic chromatograms of the four different origins of Herba Cistanche were significantly different.[Conclusions]This characteristic chromatogram method has good reproducibility and can be used to distinguish 4 different origins of Herba Cistanche,C.deserticola Y.C.Ma,C.tubulosa(Schenk)Wight,C.sinensis G.Beck and C.salsa(C.A.Mey.)G.Beck.
基金Guangxi Key R&D Program Project (GK AB19110027).
文摘[Objectives]This study was conducted to establish characteristic chromatograms of of the volatile oil of Xinyi Biyan Pills by gas chromatography,discover possible problems in the production processes of different manufacturers,and further improve the quality control methods.[Methods]The volatile oil in samples was extracted and tested by gas chromatography to collect chromatograms,which were analyze and evaluated by the similarity evaluation software of chromatographic fingerprints of traditional Chinese medicine.[Results]Nineteen common peaks were calibrated in the characteristic chromatograms;and the characteristic chromatograms of samples produced by different manufacturers were obviously different.[Conclusions]Controlling the volatile components in Xinyi Biyan Pills by the established characteristic chromatograms of GC is accurate and feasible,and can be used as a quality control method for Xinyi Biyan Pills.
基金Supported by Major Project of Nanning Scientific Research and Technology Development Plan in 2020(20201048)。
文摘[Objectives]To establish a HPLC characteristic spectrum of honeysuckle stem formula granules,and to evaluate the quality consistency based on the standard decoction.[Methods]Using Agilent ZORBAX SB-C_(18)(5μm,250 mm×4.6 mm)chromatographic column;gradient elution with acetonitrile-0.4%phosphoric acid solution(0.2:99.8,V/V),column temperature at 25℃;detection wavelength at 236 nm;flow rate 1.0 mL/min;using"Similarity Evaluation System for Chromatographic Fingerprint of Traditional Chinese Medicine",to evaluate the similarity of the characteristic chromatogram of crude drug,standard decoction and formula granules of honeysuckle stem.[Results]The similarity of characteristic chromatogram was higher than 0.94,and 6 components were identified from 10 characteristic peaks.[Conclusions]The established method can more comprehensively reflect the overall appearance of the chemical substances in the honeysuckle stem and the transmission law,and can provide an experimental basis for the consistency of the quality of the honeysuckle stem formula granules.
基金the National Natural Science Foundation of China under contract No.49976027 the Important Topic of Scientific Research of the State 0ceanic Administration, China, on the construction system of oil fingerprinting database and the key technology (from 2004 to 2005 ).
文摘By gas chromatogram, six crude oils fingerprinting distributed in four oilfields and four oil platforms were analyzed and the corre- sponding normal paraffin hydrocarbon ( including pristane and phytane) concentration was obtained by the internal standard methed. The normal paraffin hydrocarbon distribution patterns of six crude oils were built and compared. The cluster analysis on the normal paraffin hydrocarbon concentration was conducted for classification and some ratios of oils were used for oils comparison. The results indicated: there was a clear difference within different crude oils in different oil fields and a small difference between the crude oils in the same oil platform. The normal paraffin hydrocarbon distribution pattern and ratios, as well as the cluster analysis on the nomad paraffin hydrocarbon concentration can have a better differentiation result for the crude oils with small difference than the original gas chromatogram.
基金supported by the Industry-University-Research Cooperation Program from Science and Technology Department of Guangdong Province (No.: 2013B090600058)the National Key Research and Development Program of China (2017YFC170116)
文摘DNA barcoding and HPLC specific chromatogram were used to identify three kinds of Plumeria flowers respectively. DNAs extracted from the three Plumeria species were amplified by PCR with universal primers, and the psbA-trnH region was selected. All the amplified products were sequenced and the results were analyzed by MEGA 5.0. Chemometric methods including principal components analysis and hierarchical clustering analysis were conducted on the SAS 9.0 software to demonstrate the variability among samples. In conclusion, the psbA-trnH of all samples were successfully amplified from total DNA and sequenced. These three varieties of Plumeria can be differentiated by the psbA-trnH region and clustered into three groups respectively through building neighbor joining tree, which conformed to their germplasm origins. However, it was hard to distinguish them by HPLC specific chromatograms combined with chemometrics analysis. These indicated that DNA barcoding was a promising and reliable tool for the identification of three kinds of Plumeria flowers compared to HPLC specific chromatogram generally used. It could be treated as a powerful complementary method for traditional authentication, especially for those varieties which are difficult to be identified by conventional chromatography.
基金supported by the National Natural Science Foundation of China, No. 30960398the 47th Post-doctoral Scientific Foundation of China, No. 20100470376the Natural Science Foundation of Yunnan Province, No.2009CD178
文摘Selective cerebral deep hypothermia and blood flow occlusion can enhance brain tolerance to ischemia and hypoxia and reduce cardiopulmonary complications in monkeys. Excitotoxicity induced by the release of a large amount of excitatory amino acids after cerebral ischemia is the major mechanism underlying ischemic brain injury and nerve cell death. In the present study, we used selective cerebral deep hypothermia and blood flow occlusion to block the bilateral common carotid arteries and/or bilateral vertebral arteries in rhesus monkey, followed by reperfusion using Ringer's solution at 4~C. Microdialysis and transmission electron microscope results showed that selective cerebral deep hypothermia and blood flow occlusion inhibited the release of glutamic acid into the extracellular fluid in the brain frontal lobe and relieved pathological injury in terms of the ultrastructure of brain tissues after severe cerebral ischemia. These findings indicate that cerebral deep hypothermia and blood flow occlusion can inhibit cytotoxic effects and attenuate ischemic/ hypoxic brain injury through decreasing the release of excitatory amino acids, such as glutamic acid.
基金This work was supported by the National Natural Science Foundation of China(No.20443005)the Nanotechnology Special Projects of Shanghai(No.0352nm123)
文摘A novel artificial site specific cleavage reagent, with peptide nucleic acid (PNA) as sequence-recognizing moiety and cerium (IV) ions as “scissors” for cleaving target DNA, was synthesized. Subsequently, it was employed in the cleavage of target 26-mer single-stranded DNA (ssDNA), which has 10-mer sequence complementary with PNA recognizer in the hybrids, under physiological conditions. Reversed-phase high-performance liquid chromatogram (RPHPLC) experiments indicated that the artificial site specific cleavage reagent could cleave the target DNA specifically.
基金Supported by Natural Science Foundation Project of Guangxi(2016GXNSFBA380014)Program of Self-raised Fund of Ethnic Medicine of Guangxi Traditional Chinese Medicine(GZZC16-24)+5 种基金Scientific Research Project of Institutions of Higher Learning in Guangxi(KY2015YB160)Scientific Research Project of Guangxi University of Traditional Chinese Medicine(2015LX005)Key Laboratory Project of Guangxi Zhuang and Yao Medicine(Gui Ke Ji Zi:2014,No.32)Collaborative Innovation Center Project of Zhuang and Yao Medicine(Gui Jiao Ke Yan:2013,No.20)Guangxi Key Discipline(Zhuang Medicine Study)Project(Gui Jiao Ke Yan:2013,No.16)Bagui Scholar Program"Innovation Theory and Efficacy Studies of Traditional Chinese Medicine"
文摘[Objectives] To establish fingerprint chromatogram of Tetracera asiatica and provide basis for controlling and assessing the quality of Tetracera asiatica.[Methods] The high-performance liquid chromatography( HPLC) method was used. Phenomenex C18( 5 μm,4. 6 ×250 mm),acetonitrile-0. 1% phosphoric acid water,gradient elution,flow rate 1 m L/min,detection wavelength 214 nm,and column temperature 25 ℃. The fingerprint chromatogram of 10 batches of samples of Tetracera asiatica was determined for similarity comparison. [Results] It established HPLC fingerprint chromatogram of Tetracera asiatica produced in Guangxi,determined a total of 13 common fingerprint peaks. The similarity of 10 batches of Tetracera asiatica was > 0. 9.[Conclusions] The method is rapid and accurate and can provide references for assessing the quality of Tetracera asiatica.
基金Supported by Scientific Research and Technology Development Project of Nanning City(20173158-5).
文摘[Objectives]This study aimed to establish HPLC chromatograms of decoction pieces,standard decoction and formula granules of Spica Prunellae.[Methods]The chromatographic conditions were as follows:column,SHISEIDO CAPCELL PAK C18 MGII column(4.6 mm×250 mm,5μm);mobile phase,acetonitrile-0.1%phosphoric acid;gradient elution;detection wavelength,280 nm;flow rate,1.0 mL/min;and column temperature,30℃.The correlation between the decoction pieces,standard decoction and formula granules of Spica Prunellae was analyzed by specific chromatograms.[Results]The fingerprint chromatograms of decoction pieces,standard decoction and formula granules of Spica Prunellae showed five common peaks,with good correlation.Among the five common peaks,four of them were tanshinol,protocatechuic acid,caffeic acid and rosmarinic acid.[Conclusions]The main chemical constituents of decoction pieces,standard decoction and formula granules of Spica Prunellae are basically the same.The HPLC specific chromatogram established can be used for the quality control of Spica Prunellae formula granules.
基金Supported by National Natural Science Foundation of China(81260673)
文摘[Objectives] To study the typical HPLC chromatogram of petroleum ether in Abutilon indicum (L.) Sweet from different habitats, in order to provide experimental basis for the quality control of A. indicum and the spectrum-efficacy relationship of petroleum ether.[Methods] The HPLC chromatogram of petroleum ether was obtained using Agilent SB-C 18 (4.6 mm×250 mm, 5 μm) and acetine-0.1% phosphoric acid solution for gradient elution at temperature of 30 ℃, flow rate of 1.0 mL/min and detection wavelength of 205 nm.[Results] The typical HPLC chromatogram of petroleum ether in A. indicum was preliminarily established, with 12 characteristic peaks. It was verified by A. indicum from different habitats, characterized by reproducibility and stability.[Conclusions] Typical HPLC chromatogram provides a stable new method for the quality control of petroleum ether in A. indicum . This study provides experimental basis for further study on the medicinal parts of A. indicum .
文摘A defect of chromatogram in a 35kV oil-immersed three-phase one-piece electric reactor in a 500kV substation。The initial analysis suggests that the defect is caused by the loose connection of the iron core magnet shield (magnet shield layer of iron core or earthling top). Examination of winding DC resistance, DGA and other relevant examinations were carried out to investigate the defect reasons., which is demonstrated by the dismantlement. In-depth study is taken and corresponding prevention measures are put forward in the paper.
文摘Ⅰ. INTRODUCTION In the last few years, much effort has been devoted to developing the expert system for liquid chromatography (ESLC). In our previous papers, a strategy for the development of ESLC was established. Establishment of a chromatogram base is one of the most important aspects in developing ESLC. Due to the fact that one of the most time-consuming and often frustrating jobs in chromatographic lab is to develop LC method for a
文摘The effect of copper concentration on the performance of the catalytic reaction between silicon and methyl chloride was investigated using online gas chromatogram. The catalyst concentration greatly influences various aspects of the direct organosilane synthesis process, including the reaction rate, the selec- tivity, and the silicon conversion. The reaction activity and the silicon conversion increase as the catalyst concentration increases. However, the reaction selectivity decreases for the catalyst concentrations more .than 9 wt.%. The cross-sections of deactivated contact mass particles were observed by optical microscopy and analyzed by scanning electron microscope combined with energy dispersive X-ray detector (SEM-EDX) The observations showed that a textured substance formed on the original flat surface of the silicon particles after deactivation with copper only in a shallow surface layer of the contact mass. This indicates that the copper diffusion is the rate limiting step which causes the reaction deactivation.
文摘Large size self-sustained film with considerable thickness ranging from 30 to 500 μm was prepared with sol-gel method by using dimethyldiethoxysilane/tetraethoxysilane composite alkoxide as precursor. The film exhibits good plasticity as well. Various factors that may influence the film properties were investigated. IR and AFM techniques were adopted to study the film structure and surface morphology. Gas chromatogram/mass spectrum technique was also adopted to characterize the network structure of the material through identification of different polymers formed during hydrolysis and condensation course.