In order to understand the composition and structure of herbicidal active substance from the root of Flaveria bidentis （L.） Kuntze, the isolation and structural identification were researched in this paper. The crud...In order to understand the composition and structure of herbicidal active substance from the root of Flaveria bidentis （L.） Kuntze, the isolation and structural identification were researched in this paper. The crude extract from the root ofF. bidentis （L.） Kuntze was extracted by petroleum ether, ethyl acetate, and water saturation of n-butyl alcohol, respectively, and the extraction fluid was separated by using the method of TLC, then the main fraction was separated by HPLC, and the structure of the herbicidal active substance was analyzed by LC-MS, elemental analysis and ~H-NMR. The results showed that the petroleum extraction had the strongest herbicidal activity, and the purple blue stripe separated by TLC had the strongest effect on Digitaria sanguinalis. The herbicidal active substance was identified as ct-terthienyl according to the data of LC-MS, elemental analysis and 1H-NMR.展开更多
Aimed at the problem of classification of non-hydrocarbons of crude oil, the theoretical standpoint that the polarity of a compound depends on the whole structure and composition of molecule instead of a kind of heter...Aimed at the problem of classification of non-hydrocarbons of crude oil, the theoretical standpoint that the polarity of a compound depends on the whole structure and composition of molecule instead of a kind of heteroatom or its functional group was presented. A method was established for the systematically structural identification of nitric compounds in crude oil. The pre-fractionation of a crude oil sample into 7 fractions was performed by di- adsorption column chromatography with neutral aluminum oxide and silica gel. Subsequently, the individual components were obtained by using capillary column gas chromatography, and the types of compounds were detected by a mass spectrometer. In combination with a chemometric resolution, the compounds of fraction were further identified. This method can relieve the difficulty of classical analysis in identifying those species with very low contents or without being completely separated. The structures of 168 nitric compounds in a crude oil sample were determined by this method.展开更多
AIM: To analyze the major constituents in Radix Scrophulariae(Scrophularia ningpoensis). METHOD: Radix Scrophulariae was analyzed by HPLC coupled with electrospray ionization quadrupole time-of-flight tandem mass spec...AIM: To analyze the major constituents in Radix Scrophulariae(Scrophularia ningpoensis). METHOD: Radix Scrophulariae was analyzed by HPLC coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry(ESI-Q-TOF MS/MS). Compounds were separated by HPLC using a C18 column and gradient elution of acetonitrile and 0.1 %(V/V) acetic acid-water. Negative ion mode was employed. RESULTS: A total of thirty-six compounds, including fourteen iridoid glycosides, nineteen phenylpropanoid glycosides, and three organic acids, were identified from Radix Scrophulariae based on the accurate mass measurement of precursor and product ions. Twenty-one of the constituents were identified by comparing their retention times(tR) and ESI-MS/MS data with those of reference standards and/or previous publications, while another fifteen compounds were tentatively identified or deduced according to their Q-TOF MS/MS data which afforded sufficient structural information. CONCLUSION: It is believed that this study is useful for the identification of constituents in Radix Scrophulariae, as well as related plants and complex prescriptions.展开更多
[Objective]Staphylococcus arthritis became an increasingly significant health problem in intensive chicken farming in China.[Method]In this study,a bacteria strain was isolated from the broiler chicken suffering from ...[Objective]Staphylococcus arthritis became an increasingly significant health problem in intensive chicken farming in China.[Method]In this study,a bacteria strain was isolated from the broiler chicken suffering from arthritis and named as the strain Gg1.[Result]It was then identified as Staphylococcus chromogenes by the biochemical tests and phylogenetic tree analysis based on 16S rDNA sequence.Furthermore,the catalase（katA）gene was amplified by PCR using the designed primers,and the expected fragment was 1 232 bp long encoding a protein of 410 amino acids that shares the conserved motifs including catalase,heme-binding ligand and active center motif.Six phosphorylation sites（Ser95,Thr96,Ser241,Ser242,Thr281,Ser338）,four conserved residues（Ser95,His216,Tyr281,Asp341）and two active sites（His56,Asn129）were demonstrated by multiple sequence alignment and homology comparisons.The homology modeling of 3D structure of katA protein was done by SWISSMODEL server based on the template retrieved from the catalase（PDB：2ISA_A）of Vibrio salmonicida.The katA protein represents a four-domain globular protein,the quality and reliability of the resulting protein structure was further verified by Ramachandran plot.[Conclusion]To our knowledge,this is the first report of S.chromogenes linked to arthritis in chicken and the bioinformatic characterization of its katA gene.展开更多
Endophytic fungi are widely found in almost all kinds of plants. Many endophytic fungi can produce some physio-logical active compounds, which are same to or analog to those isolated from their hosts. Producing physio...Endophytic fungi are widely found in almost all kinds of plants. Many endophytic fungi can produce some physio-logical active compounds, which are same to or analog to those isolated from their hosts. Producing physiological active com-pounds through microbial fermentation can give a new way to resolve resource limitation and to find out alternative source. Through the methods of organic solvent extraction, thin layer chromatography (TLC) and column chromatography, compound I was isolated, purified from the liquid fermentation metabolites of the taxoids-produced endophytic fungi (Alternaria. alternata var. taxi 1011 Y. Xiang et LU An-guo) that was screened from the bark of Taxus. cuspidata Sieb.et Zucc.. Compound I was identified as one kind of taxoids type III, based on the analyzing results by using the methods of ultraviolet spectroscopy (UV), infrared spectroscopy (IR), mass spectrometry (MS) and nuclear magnetic resonance spectroscopy (NMR). This study provides a com-pleted method for separation and purification of the endophytic fungi as well as structure identification of its fermentation me-tabolite展开更多
To separate, purify and identify the antioxidative compositions of black rice, using total antioxidation capacity （TAC） as an activity-monitoring parameter, different fractions of black rice antioxidative extracts w...To separate, purify and identify the antioxidative compositions of black rice, using total antioxidation capacity （TAC） as an activity-monitoring parameter, different fractions of black rice antioxidative extracts were obtained using solvents of different polarities such as petroleum ether, chloroform, ethyl acetate and normal butyl alcohol. The main anfioxidative components were separated from the strongest antioxidative fractions by using Sephadex LH-20 resin and the structures were analyzed by ultraviolet-vis, infra-red, ESI-MS, ^1H-NMR and ^13C-NMR spectrums. Results showed that the water fraction and normal butyl alcohol antioxidafive extract fraction of black rice had the strongest antioxidation capacities and their TACs reached 383 and 392 ku g^-1, respectively. Four main antioxidative components were separated from the water fraction and their TACs reached 976, 878, 1 134 and 1087 ku g^-, respectively. The spectroscopy analysis indicated that the four active components of the antioxidative extract of black rice were four anthocyanin compounds of malvidin, pelargonidin- 3, 5-diglucoside, cyaniding-3-glucoside and cyaniding-3, 5-diglucoside. It is concluded that the anthocyanin compounds are the most important substantial foundations for antioxidation.展开更多
In order to understand the compsition and structure of herbicidal component of Pythium aphanidermatum,the isolation and structural indentification were researched.The culture filtrate was extracted by ethyl acetate,pe...In order to understand the compsition and structure of herbicidal component of Pythium aphanidermatum,the isolation and structural indentification were researched.The culture filtrate was extracted by ethyl acetate,petroleum,and chloroform with the same volume respectively and the activity of the crude toxin was bioassayed.The toxin was separated by using the method of thin layer chromatography（TLC）,then the main fraction was separated by HPLC,and the structure was analyzed by the sepctrum of IR,13C-NMR and 1HNMR.The results showed that the ethyl acetate extracts had the strongest herbicidal activity.Using the method of TLC,the bioassay results showed that the extracts with Rf 0.19 had the strongest effect on weeds and the inhibition to Digitaria sanguinalis and Amaranthus retroflexus reached five levels,and the component was proved to be dimethyl o-phthalate from the spectrum of IR,13C-NMR and 1HNMR,which was one of the components from the toxin,and it had herbicidal activity.展开更多
To improve the accuracy and anti-noise ability of the structural damage identification method,a bridge damage identification method is proposed based on a deep belief network(DBN).The output vector is used to establis...To improve the accuracy and anti-noise ability of the structural damage identification method,a bridge damage identification method is proposed based on a deep belief network(DBN).The output vector is used to establish the nonlinear mapping relationship between the mode shape and structural damage.The hidden layer of the DBN is trained through a layer-by-layer pre-training.Finally,the backpropagation algorithm is used to fine-tune the entire network.The method is validated using a numerical model of a steel truss bridge.The results show that under the influence of noise and modeling uncertainty,the damage identification method based on the DBN can identify the accurate damage location and degree identification compared with the traditional damage identification method based on an artificial neural network.展开更多
In this paper, structure identification of an uncertain network coupled with complex-variable chaotic systems is in- vestigated. Both the topological structure and the system parameters can be unknown and need to be i...In this paper, structure identification of an uncertain network coupled with complex-variable chaotic systems is in- vestigated. Both the topological structure and the system parameters can be unknown and need to be identified. Based on impulsive stability theory and the Lyapunov function method, an impulsive control scheme combined with an adaptive strategy is adopted to design effective and universal network estimators. The restriction on the impulsive interval is relaxed by adopting an adaptive strategy. Further, the proposed method can monitor the online switching topology effectively. Several numerical simulations are provided to illustrate the effectiveness of the theoretical results.展开更多
Polysaccharide produced by mutated strain of Streptococcus zooepidemicus was purified by the procedures including Savage method, quaternary ammonium compound precipitation, DEAE-cellulose(DE52) chromatography and Seph...Polysaccharide produced by mutated strain of Streptococcus zooepidemicus was purified by the procedures including Savage method, quaternary ammonium compound precipitation, DEAE-cellulose(DE52) chromatography and Sephadex G-75 gel filtration. The structure of the purified polysaccharide has been characterized by means of chemical composition analysis,13C NMR spectrum, infrared spectrum and circular dichroism (CD). All the results showed that the purified polysaccharide was hyaluronic acid (HA). The single helix conformation of the purified HA was determined by Congo red experiment. The molecular weight of the HA was about 1.16×106D, which was measured by viscosity method.展开更多
The interpretation of regional gravity and magnetic data, especially the extracted information about concealed targets and structures, provide important evidence for geological structure research, oil-gas resource ass...The interpretation of regional gravity and magnetic data, especially the extracted information about concealed targets and structures, provide important evidence for geological structure research, oil-gas resource assessment, mineral potential forecast and prospective area delineation. Several interpretation methods have been proposed to determine structural boundary, including vertical derivative, horizontal first-order derivative, total horizontal derivative, total gradient modulus, tilt derivative, and theta graph, and each have their advantages and disadvantages. This study used the tilt derivate method to obtain bouguer gravity anomalies in the Beya area, as shown in Fig. 1a.展开更多
In our previous work,we found a new method by chance for the synthesis of thiazole derivatives with diversified substitutes on 2-and 5-positions of the thiazole scaffold which was published in Chinese Chemical Letters...In our previous work,we found a new method by chance for the synthesis of thiazole derivatives with diversified substitutes on 2-and 5-positions of the thiazole scaffold which was published in Chinese Chemical Letters[2014,Vol.25 p.411].The structures were identified by ~1H NMR,^（13）C NMR and HRMS as 2-alkoxy-4-amino-Narylthiazole-5-carboxamides.展开更多
Nafamostat mesylate is a serine protease inhibitor used in the treatment of acute pancreatitis.The impurities in nafamostat mesylate,the active pharmaceutical ingredient(API),were profiled via high performance liquid ...Nafamostat mesylate is a serine protease inhibitor used in the treatment of acute pancreatitis.The impurities in nafamostat mesylate,the active pharmaceutical ingredient(API),were profiled via high performance liquid chromatography tandem ion trap coupled with time-of-flight mass spectrometer(HPLC-IT-TOF/MS).The chromatography was performed on an ACE-3 C18 column(200 mm4.6 mm,3 mm)using methanol and 0.1%formic acid in purified water as mobile phase at a flow rate of 1.0 mL/min.The ions were detected by IT-TOF/MS with a full-scan mass analysis from m/z 100 to 800.In total,eleven impurities were detected in nafamostat mesylate API.The impurity profile was estimated based on the HPLC-IT-TOF/MS data,including accurate masses,MSn fingerprints of fragmentation pathways and a series of double-charged ions.Finally,seven impurities were identified and reported for the first time.The results will provide technical support for the quality control and clinical safety of nafamostat mesylate.展开更多
In this paper, we address the problem of structure identification of Volterra models. It consists in estimating the model order and the memory length of each kernel. Two methods based on input-output crosscumulants ar...In this paper, we address the problem of structure identification of Volterra models. It consists in estimating the model order and the memory length of each kernel. Two methods based on input-output crosscumulants are developed. The first one uses zero mean independent and identically distributed Caussian input, and the second one concerns a symmetric input sequence. Simulations are performed on six models having different orders and kernel memory lengths to demonstrate the advantages of the proposed methods.展开更多
Several parameters of a commercial Si-based Schottky barrier diode (SBD) with unknown metal material and semiconductor-type have been investigated in this work from dark forward and reverse I-V characteristics in the ...Several parameters of a commercial Si-based Schottky barrier diode (SBD) with unknown metal material and semiconductor-type have been investigated in this work from dark forward and reverse I-V characteristics in the temperature (T) range of [274.5 K - 366.5 K]. Those parameters include the reverse saturation current (I<sub>s</sub>), the ideality factor (n), the series and the shunt resistances (R<sub>s</sub> and R<sub>sh</sub>), the effective and the zero bias barrier heights (Φ<sub>B</sub> and Φ<sub>B0</sub>), the product of the electrical active area (A) and the effective Richardson constant (A**), the built-in potential (V<sub>bi</sub>), together with the semiconductor doping concentration (N<sub>A</sub> or N<sub>D</sub>). Some of them have been extracted by using two or three different methods. The main features of each approach have been clearly stated. From one parameter to another, results have been discussed in terms of structure performance, comparison on one another when extracted from different methods, accordance or discordance with data from other works, and parameter’s temperature or voltage dependence. A comparison of results on Φ<sub>B</sub>, ΦB0</sub>, n and N<sub>A</sub> or N<sub>D</sub> parameters with some available data in literature for the same parameters, has especially led to clear propositions on the identity of the analyzed SBD’s metal and semiconductor-type.展开更多
Phytochemical investigation of the leaves of Premna microphylla Turcz led to the isolation of 13 known compounds. Based on spectroscopic and chemical evidences, their structures were identified as diosmetin （1）, blu...Phytochemical investigation of the leaves of Premna microphylla Turcz led to the isolation of 13 known compounds. Based on spectroscopic and chemical evidences, their structures were identified as diosmetin （1）, blumenol A （2）, （3S,5R,6S,7E,9R）-5,6-epoxy-3,9-dihydroxy-7-megastigmene （3）, 3β-hydroxy-5a,6a-epoxy-γ-megastigmen-9-one （4）, ixerol B （5）, （-）-dehydrovomifoliol （6）, 3S,5R-dihydroxy-6S,7-megastigmadien-9-one （7）, loliotide （8）, （＋）-dehydrololiolide （9）, （＋）-medioresinol （10）, 4-oxopinoresinol （11）, tormentic acid （12）, and indole-3-carboxylic acid （13）. Compounds 2-13 described above were isolated from this genus for the first time.展开更多
The aim of current study was to investigate the chemical constituents from the flowers of Rhododendron molle G. Don. The isolation and purification of components were achieved by a series of chromatography including s...The aim of current study was to investigate the chemical constituents from the flowers of Rhododendron molle G. Don. The isolation and purification of components were achieved by a series of chromatography including silica gel, Sephadex LH-20, and reversed-phase HPLC. Their structures were identified based on 1D, 2D NMR, and mass spectral analysis. Fifteen known compounds were isolated and their structures were identified as 2E,4Z-abscisic acid（1）, 2α-hydroxy-oleanolic acid（2）, oleanic acid（3）, asiatic acid（4）, benzyl glucoside（5）, dibutyl phthalate（6）, β-sitosterol（7）, vitexin（8）, quercetin（9）, steraric acid（10）, rhodomollein I（11）, rhodojaponin VI（12）, rhodomollein XI（13）, rhodojaponin II（14）, kalmanol（15）. Compounds 1–10 were isolated from Rhododendron molle for the first time.展开更多
Chemical constituents of the whole herb of Rhodiola kirilowii(Regl) Maxim.were investigated.The separation of the constituents was achieved by using a combination of various chromatographic techniques including column...Chemical constituents of the whole herb of Rhodiola kirilowii(Regl) Maxim.were investigated.The separation of the constituents was achieved by using a combination of various chromatographic techniques including column chromatography over silica gel,ODS,Sephadex LH-20 and reversed-phase HPLC.Their structures were elucidated by spectroscopic techniques including 1D and 2D NMR spectroscopy.Eleven compounds were obtained and identified as 4-hydroxyphenylethyl-(4'- methoxyphenylethyl)ether(1),1-(2-hydroxy-2-methylbutanoate)-β-D-glucopyranose(2),4-ethoxy-phenylethanol acetate(3),p-hydroxyacetophenone (4),p-hydroxy-benzoic acid ethylester(5),4-hydroxybenzoic acid(6),4-hydroxybenzaldehyde(7),R(-)-mellein (8),stigmasterol(9),4-methoxy-phenylethanol(10),and methylgallate(11).Among them,1 and 2 are new compounds; compounds 3,5,7,8,and 10 were isolated from Rhodiola genus for the first time;and compounds 4,6,9,and 11 were isolated from Rhodiola kirilowii(Regl) Maxim.for the first time.展开更多
Fifteen compounds were isolated from the processed seeds of Strychnos nux-vomica and were identified as follows：strychnine（1）,brucine（2）,pseudostrychnine（3）,pseudobrucine（4）,secoxyloganin（5）,caffeic acid（6...Fifteen compounds were isolated from the processed seeds of Strychnos nux-vomica and were identified as follows：strychnine（1）,brucine（2）,pseudostrychnine（3）,pseudobrucine（4）,secoxyloganin（5）,caffeic acid（6）,p-hydroxybenzoic acid（7）,p-hydroxyphenylacetic acid（8）,uvaol（9）,stigmasta-7,22,25-triene-3-ol（10）,lupeol（11）,11-oxo-α-amyrin palmitate（12）,catechol（13）,maltol（14）,adenosine（15）.Compounds 5-15 were isolated from genus Strychnos for the first time.展开更多
基金the National Natural Science Foundation of China(31171877)
文摘In order to understand the composition and structure of herbicidal active substance from the root of Flaveria bidentis （L.） Kuntze, the isolation and structural identification were researched in this paper. The crude extract from the root ofF. bidentis （L.） Kuntze was extracted by petroleum ether, ethyl acetate, and water saturation of n-butyl alcohol, respectively, and the extraction fluid was separated by using the method of TLC, then the main fraction was separated by HPLC, and the structure of the herbicidal active substance was analyzed by LC-MS, elemental analysis and ~H-NMR. The results showed that the petroleum extraction had the strongest herbicidal activity, and the purple blue stripe separated by TLC had the strongest effect on Digitaria sanguinalis. The herbicidal active substance was identified as ct-terthienyl according to the data of LC-MS, elemental analysis and 1H-NMR.
文摘Aimed at the problem of classification of non-hydrocarbons of crude oil, the theoretical standpoint that the polarity of a compound depends on the whole structure and composition of molecule instead of a kind of heteroatom or its functional group was presented. A method was established for the systematically structural identification of nitric compounds in crude oil. The pre-fractionation of a crude oil sample into 7 fractions was performed by di- adsorption column chromatography with neutral aluminum oxide and silica gel. Subsequently, the individual components were obtained by using capillary column gas chromatography, and the types of compounds were detected by a mass spectrometer. In combination with a chemometric resolution, the compounds of fraction were further identified. This method can relieve the difficulty of classical analysis in identifying those species with very low contents or without being completely separated. The structures of 168 nitric compounds in a crude oil sample were determined by this method.
基金supported by the National Natural Science Foundation of China(Nos.30901956,30973965)2011’Program for Excellent Scientific and Technological Innovation Team of Jiangsu Higher Education and the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘AIM: To analyze the major constituents in Radix Scrophulariae(Scrophularia ningpoensis). METHOD: Radix Scrophulariae was analyzed by HPLC coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry(ESI-Q-TOF MS/MS). Compounds were separated by HPLC using a C18 column and gradient elution of acetonitrile and 0.1 %(V/V) acetic acid-water. Negative ion mode was employed. RESULTS: A total of thirty-six compounds, including fourteen iridoid glycosides, nineteen phenylpropanoid glycosides, and three organic acids, were identified from Radix Scrophulariae based on the accurate mass measurement of precursor and product ions. Twenty-one of the constituents were identified by comparing their retention times(tR) and ESI-MS/MS data with those of reference standards and/or previous publications, while another fifteen compounds were tentatively identified or deduced according to their Q-TOF MS/MS data which afforded sufficient structural information. CONCLUSION: It is believed that this study is useful for the identification of constituents in Radix Scrophulariae, as well as related plants and complex prescriptions.
基金Supported by the National Natural Science Foundation of China (No.31272692,No.30800847)
文摘[Objective]Staphylococcus arthritis became an increasingly significant health problem in intensive chicken farming in China.[Method]In this study,a bacteria strain was isolated from the broiler chicken suffering from arthritis and named as the strain Gg1.[Result]It was then identified as Staphylococcus chromogenes by the biochemical tests and phylogenetic tree analysis based on 16S rDNA sequence.Furthermore,the catalase（katA）gene was amplified by PCR using the designed primers,and the expected fragment was 1 232 bp long encoding a protein of 410 amino acids that shares the conserved motifs including catalase,heme-binding ligand and active center motif.Six phosphorylation sites（Ser95,Thr96,Ser241,Ser242,Thr281,Ser338）,four conserved residues（Ser95,His216,Tyr281,Asp341）and two active sites（His56,Asn129）were demonstrated by multiple sequence alignment and homology comparisons.The homology modeling of 3D structure of katA protein was done by SWISSMODEL server based on the template retrieved from the catalase（PDB：2ISA_A）of Vibrio salmonicida.The katA protein represents a four-domain globular protein,the quality and reliability of the resulting protein structure was further verified by Ramachandran plot.[Conclusion]To our knowledge,this is the first report of S.chromogenes linked to arthritis in chicken and the bioinformatic characterization of its katA gene.
文摘Endophytic fungi are widely found in almost all kinds of plants. Many endophytic fungi can produce some physio-logical active compounds, which are same to or analog to those isolated from their hosts. Producing physiological active com-pounds through microbial fermentation can give a new way to resolve resource limitation and to find out alternative source. Through the methods of organic solvent extraction, thin layer chromatography (TLC) and column chromatography, compound I was isolated, purified from the liquid fermentation metabolites of the taxoids-produced endophytic fungi (Alternaria. alternata var. taxi 1011 Y. Xiang et LU An-guo) that was screened from the bark of Taxus. cuspidata Sieb.et Zucc.. Compound I was identified as one kind of taxoids type III, based on the analyzing results by using the methods of ultraviolet spectroscopy (UV), infrared spectroscopy (IR), mass spectrometry (MS) and nuclear magnetic resonance spectroscopy (NMR). This study provides a com-pleted method for separation and purification of the endophytic fungi as well as structure identification of its fermentation me-tabolite
基金This study was supported by the National Natural Science Foundation of China(39870537)the Natural Science Foundation of Guangdong Province,China(990519).
文摘To separate, purify and identify the antioxidative compositions of black rice, using total antioxidation capacity （TAC） as an activity-monitoring parameter, different fractions of black rice antioxidative extracts were obtained using solvents of different polarities such as petroleum ether, chloroform, ethyl acetate and normal butyl alcohol. The main anfioxidative components were separated from the strongest antioxidative fractions by using Sephadex LH-20 resin and the structures were analyzed by ultraviolet-vis, infra-red, ESI-MS, ^1H-NMR and ^13C-NMR spectrums. Results showed that the water fraction and normal butyl alcohol antioxidafive extract fraction of black rice had the strongest antioxidation capacities and their TACs reached 383 and 392 ku g^-1, respectively. Four main antioxidative components were separated from the water fraction and their TACs reached 976, 878, 1 134 and 1087 ku g^-, respectively. The spectroscopy analysis indicated that the four active components of the antioxidative extract of black rice were four anthocyanin compounds of malvidin, pelargonidin- 3, 5-diglucoside, cyaniding-3-glucoside and cyaniding-3, 5-diglucoside. It is concluded that the anthocyanin compounds are the most important substantial foundations for antioxidation.
基金supported by a grant from the National High Technology Research and Development Program of China (2006AA10A214)the Natural Science Foundation of Hebei Province,China (C2007000464)
文摘In order to understand the compsition and structure of herbicidal component of Pythium aphanidermatum,the isolation and structural indentification were researched.The culture filtrate was extracted by ethyl acetate,petroleum,and chloroform with the same volume respectively and the activity of the crude toxin was bioassayed.The toxin was separated by using the method of thin layer chromatography（TLC）,then the main fraction was separated by HPLC,and the structure was analyzed by the sepctrum of IR,13C-NMR and 1HNMR.The results showed that the ethyl acetate extracts had the strongest herbicidal activity.Using the method of TLC,the bioassay results showed that the extracts with Rf 0.19 had the strongest effect on weeds and the inhibition to Digitaria sanguinalis and Amaranthus retroflexus reached five levels,and the component was proved to be dimethyl o-phthalate from the spectrum of IR,13C-NMR and 1HNMR,which was one of the components from the toxin,and it had herbicidal activity.
基金The National Natural Science Foundation of China(No.51378104)。
文摘To improve the accuracy and anti-noise ability of the structural damage identification method,a bridge damage identification method is proposed based on a deep belief network(DBN).The output vector is used to establish the nonlinear mapping relationship between the mode shape and structural damage.The hidden layer of the DBN is trained through a layer-by-layer pre-training.Finally,the backpropagation algorithm is used to fine-tune the entire network.The method is validated using a numerical model of a steel truss bridge.The results show that under the influence of noise and modeling uncertainty,the damage identification method based on the DBN can identify the accurate damage location and degree identification compared with the traditional damage identification method based on an artificial neural network.
基金Project supported by the Tianyuan Special Funds of the National Natural Science Foundation of China(Grant No.11226242)the Natural Science Foundation of Jiangxi Province of China(Grant No.20122BAB211006)
文摘In this paper, structure identification of an uncertain network coupled with complex-variable chaotic systems is in- vestigated. Both the topological structure and the system parameters can be unknown and need to be identified. Based on impulsive stability theory and the Lyapunov function method, an impulsive control scheme combined with an adaptive strategy is adopted to design effective and universal network estimators. The restriction on the impulsive interval is relaxed by adopting an adaptive strategy. Further, the proposed method can monitor the online switching topology effectively. Several numerical simulations are provided to illustrate the effectiveness of the theoretical results.
文摘Polysaccharide produced by mutated strain of Streptococcus zooepidemicus was purified by the procedures including Savage method, quaternary ammonium compound precipitation, DEAE-cellulose(DE52) chromatography and Sephadex G-75 gel filtration. The structure of the purified polysaccharide has been characterized by means of chemical composition analysis,13C NMR spectrum, infrared spectrum and circular dichroism (CD). All the results showed that the purified polysaccharide was hyaluronic acid (HA). The single helix conformation of the purified HA was determined by Congo red experiment. The molecular weight of the HA was about 1.16×106D, which was measured by viscosity method.
文摘The interpretation of regional gravity and magnetic data, especially the extracted information about concealed targets and structures, provide important evidence for geological structure research, oil-gas resource assessment, mineral potential forecast and prospective area delineation. Several interpretation methods have been proposed to determine structural boundary, including vertical derivative, horizontal first-order derivative, total horizontal derivative, total gradient modulus, tilt derivative, and theta graph, and each have their advantages and disadvantages. This study used the tilt derivate method to obtain bouguer gravity anomalies in the Beya area, as shown in Fig. 1a.
文摘In our previous work,we found a new method by chance for the synthesis of thiazole derivatives with diversified substitutes on 2-and 5-positions of the thiazole scaffold which was published in Chinese Chemical Letters[2014,Vol.25 p.411].The structures were identified by ~1H NMR,^（13）C NMR and HRMS as 2-alkoxy-4-amino-Narylthiazole-5-carboxamides.
基金This work was financially supported by the National Major Science and Technology Projects of China(2017ZX09101001)the Double First-Class University Project(CPU2018GY33).
文摘Nafamostat mesylate is a serine protease inhibitor used in the treatment of acute pancreatitis.The impurities in nafamostat mesylate,the active pharmaceutical ingredient(API),were profiled via high performance liquid chromatography tandem ion trap coupled with time-of-flight mass spectrometer(HPLC-IT-TOF/MS).The chromatography was performed on an ACE-3 C18 column(200 mm4.6 mm,3 mm)using methanol and 0.1%formic acid in purified water as mobile phase at a flow rate of 1.0 mL/min.The ions were detected by IT-TOF/MS with a full-scan mass analysis from m/z 100 to 800.In total,eleven impurities were detected in nafamostat mesylate API.The impurity profile was estimated based on the HPLC-IT-TOF/MS data,including accurate masses,MSn fingerprints of fragmentation pathways and a series of double-charged ions.Finally,seven impurities were identified and reported for the first time.The results will provide technical support for the quality control and clinical safety of nafamostat mesylate.
文摘In this paper, we address the problem of structure identification of Volterra models. It consists in estimating the model order and the memory length of each kernel. Two methods based on input-output crosscumulants are developed. The first one uses zero mean independent and identically distributed Caussian input, and the second one concerns a symmetric input sequence. Simulations are performed on six models having different orders and kernel memory lengths to demonstrate the advantages of the proposed methods.
文摘Several parameters of a commercial Si-based Schottky barrier diode (SBD) with unknown metal material and semiconductor-type have been investigated in this work from dark forward and reverse I-V characteristics in the temperature (T) range of [274.5 K - 366.5 K]. Those parameters include the reverse saturation current (I<sub>s</sub>), the ideality factor (n), the series and the shunt resistances (R<sub>s</sub> and R<sub>sh</sub>), the effective and the zero bias barrier heights (Φ<sub>B</sub> and Φ<sub>B0</sub>), the product of the electrical active area (A) and the effective Richardson constant (A**), the built-in potential (V<sub>bi</sub>), together with the semiconductor doping concentration (N<sub>A</sub> or N<sub>D</sub>). Some of them have been extracted by using two or three different methods. The main features of each approach have been clearly stated. From one parameter to another, results have been discussed in terms of structure performance, comparison on one another when extracted from different methods, accordance or discordance with data from other works, and parameter’s temperature or voltage dependence. A comparison of results on Φ<sub>B</sub>, ΦB0</sub>, n and N<sub>A</sub> or N<sub>D</sub> parameters with some available data in literature for the same parameters, has especially led to clear propositions on the identity of the analyzed SBD’s metal and semiconductor-type.
基金National Natural Science Foundation of China(Grant No.31270390)Program for New Century Excellent Talents in University(Grant No.NCET-08-0224)
文摘Phytochemical investigation of the leaves of Premna microphylla Turcz led to the isolation of 13 known compounds. Based on spectroscopic and chemical evidences, their structures were identified as diosmetin （1）, blumenol A （2）, （3S,5R,6S,7E,9R）-5,6-epoxy-3,9-dihydroxy-7-megastigmene （3）, 3β-hydroxy-5a,6a-epoxy-γ-megastigmen-9-one （4）, ixerol B （5）, （-）-dehydrovomifoliol （6）, 3S,5R-dihydroxy-6S,7-megastigmadien-9-one （7）, loliotide （8）, （＋）-dehydrololiolide （9）, （＋）-medioresinol （10）, 4-oxopinoresinol （11）, tormentic acid （12）, and indole-3-carboxylic acid （13）. Compounds 2-13 described above were isolated from this genus for the first time.
基金National Natural Science Foundation of China(Grant No.81172943)
文摘The aim of current study was to investigate the chemical constituents from the flowers of Rhododendron molle G. Don. The isolation and purification of components were achieved by a series of chromatography including silica gel, Sephadex LH-20, and reversed-phase HPLC. Their structures were identified based on 1D, 2D NMR, and mass spectral analysis. Fifteen known compounds were isolated and their structures were identified as 2E,4Z-abscisic acid（1）, 2α-hydroxy-oleanolic acid（2）, oleanic acid（3）, asiatic acid（4）, benzyl glucoside（5）, dibutyl phthalate（6）, β-sitosterol（7）, vitexin（8）, quercetin（9）, steraric acid（10）, rhodomollein I（11）, rhodojaponin VI（12）, rhodomollein XI（13）, rhodojaponin II（14）, kalmanol（15）. Compounds 1–10 were isolated from Rhododendron molle for the first time.
基金National Natural Science Foundation of China (Grant No.30973628).
文摘Chemical constituents of the whole herb of Rhodiola kirilowii(Regl) Maxim.were investigated.The separation of the constituents was achieved by using a combination of various chromatographic techniques including column chromatography over silica gel,ODS,Sephadex LH-20 and reversed-phase HPLC.Their structures were elucidated by spectroscopic techniques including 1D and 2D NMR spectroscopy.Eleven compounds were obtained and identified as 4-hydroxyphenylethyl-(4'- methoxyphenylethyl)ether(1),1-(2-hydroxy-2-methylbutanoate)-β-D-glucopyranose(2),4-ethoxy-phenylethanol acetate(3),p-hydroxyacetophenone (4),p-hydroxy-benzoic acid ethylester(5),4-hydroxybenzoic acid(6),4-hydroxybenzaldehyde(7),R(-)-mellein (8),stigmasterol(9),4-methoxy-phenylethanol(10),and methylgallate(11).Among them,1 and 2 are new compounds; compounds 3,5,7,8,and 10 were isolated from Rhodiola genus for the first time;and compounds 4,6,9,and 11 were isolated from Rhodiola kirilowii(Regl) Maxim.for the first time.
基金Research Platform for Quality Standard of TCM and Information System Building(Grant No.2009ZX09308-04)National S&T Major Project-Created Major New Drugs Projects(Grant No.2009ZX09311-004)
文摘Fifteen compounds were isolated from the processed seeds of Strychnos nux-vomica and were identified as follows：strychnine（1）,brucine（2）,pseudostrychnine（3）,pseudobrucine（4）,secoxyloganin（5）,caffeic acid（6）,p-hydroxybenzoic acid（7）,p-hydroxyphenylacetic acid（8）,uvaol（9）,stigmasta-7,22,25-triene-3-ol（10）,lupeol（11）,11-oxo-α-amyrin palmitate（12）,catechol（13）,maltol（14）,adenosine（15）.Compounds 5-15 were isolated from genus Strychnos for the first time.
