The a-L-rhamnopyranosyl phosphomonoesters conjugated with L-amino acid methyl esters were stereoselectively synthesized in a convenient route by utilizing H-phosphonate intermediate.
Two new minor steroidal saponins, (25R) spirostan-3β-ol-6-one-3-O-[α-L- arabinopyranosyl(1-4)]-β-D-glucopyranosidc (1) and (25S) spirost-5-en -3β, 17α, 27-triol-3-O- [α-L-arabinopyranosyl(1-6)]-β-D-glucopyranos...Two new minor steroidal saponins, (25R) spirostan-3β-ol-6-one-3-O-[α-L- arabinopyranosyl(1-4)]-β-D-glucopyranosidc (1) and (25S) spirost-5-en -3β, 17α, 27-triol-3-O- [α-L-arabinopyranosyl(1-6)]-β-D-glucopyranosidc (2) were isolated from the roots of Smilax lebrunii. Their structures were established on thc basis of chemical and spectral methods.展开更多
The reaction between D-glucose, D-ribose and 2, 2,2-trimethoxy-4, 5-diphenyl-2, 2-dihydro-1, 3, 2-dioxaphospholene were investigates by P-31 NMR and FAB-MS. The results showed that there were a lot of differences in t...The reaction between D-glucose, D-ribose and 2, 2,2-trimethoxy-4, 5-diphenyl-2, 2-dihydro-1, 3, 2-dioxaphospholene were investigates by P-31 NMR and FAB-MS. The results showed that there were a lot of differences in the reactions via pentacoordinate phosphorus compound, and it should give it significant clue to the metabolism of carbohydrate phosphate in nature.展开更多
In order to further confirm the biomimic properties of N-phosphoamino acids. A series of model compounds, analogue of phosphoryl amino acids, were synthesized and their biomimic mechanism was also investigated by NMR ...In order to further confirm the biomimic properties of N-phosphoamino acids. A series of model compounds, analogue of phosphoryl amino acids, were synthesized and their biomimic mechanism was also investigated by NMR and MS methods. The results indicated that the reactivity of phosphoryl biological small molecules was depended on the configuration, function groups and positions.展开更多
A new compound. methyl 4. 6-O-benzylidene-a-D-glucopyranoside 2. 3-cyclicphosphite ethyl ester was synthesized via the reaction of methyl 4. 6-O-benzylidene-a-D-glucopyranoside and ethyl dichlorophosphite. Its structu...A new compound. methyl 4. 6-O-benzylidene-a-D-glucopyranoside 2. 3-cyclicphosphite ethyl ester was synthesized via the reaction of methyl 4. 6-O-benzylidene-a-D-glucopyranoside and ethyl dichlorophosphite. Its structure was confirmed by NMR and MSspectral methods.展开更多
Based on the stability theory of linear time-varying continuous system, this paper investigates the synchronization of two linear bidirectionally-coupled systems. Sufficient conditions for asymptotic synchronization a...Based on the stability theory of linear time-varying continuous system, this paper investigates the synchronization of two linear bidirectionally-coupled systems. Sufficient conditions for asymptotic synchronization are obtained for general chaotic system with bidirectional coupling via linear error feedback. Since the trajectory of chaotic system is continuous and bounded, one can choose suitable coupled pararneters to satisfy the proposed criterion. The criterion can also be applied to the global synchronization for chaotic systems with linear unidirectional coupling. The chaotic Chen system and the generalized Lorenz-like system are taken as examples, the simulations verify the effectiveness of the proposed method.展开更多
A New steroidal saponin was isolated from the rhizomes of Smilax lebrunii. On the basis of spectral and chemical methods, its structure was elucidated as:(25S)spirost-5-en-3β, 17α, 27-triol-3-0-[β-D-glucopyranosyl(...A New steroidal saponin was isolated from the rhizomes of Smilax lebrunii. On the basis of spectral and chemical methods, its structure was elucidated as:(25S)spirost-5-en-3β, 17α, 27-triol-3-0-[β-D-glucopyranosyl(1-4)][α-L-arabinopyranosyl(1-6)]-β-D-glucopyranoside.展开更多
Oxyphosphorane reacted with glucose to give disaccharide which was confirmed by FAB-MS and C-13-NMR. The mechanism for formation of oligosaccharides through the participation of phosphorus was proposed.
Two minor steroidal saponins were isolated from the roots of Smilax menispermoidea.One of them is new and its structure was established as(25S) spirost-5-en-3β,17α,27-triol-3-O-[α-L-rhamnopyranosyl(1-4)]-β-D-gluco...Two minor steroidal saponins were isolated from the roots of Smilax menispermoidea.One of them is new and its structure was established as(25S) spirost-5-en-3β,17α,27-triol-3-O-[α-L-rhamnopyranosyl(1-4)]-β-D-gluco- pyranoside using spectroscopic and chemical methods.展开更多
In the presence of phosphoryl group, N-diisopropyloxy phosphoryl amino ac ids become more reactive and undergo self-catalys is to farm the peptides by coupling with amino acids or their esters in aqueous solution at l...In the presence of phosphoryl group, N-diisopropyloxy phosphoryl amino ac ids become more reactive and undergo self-catalys is to farm the peptides by coupling with amino acids or their esters in aqueous solution at low temperature. The different side chain amino acid would appear with different reactivity. It might be important for the prebiotic synthesis of protein.展开更多
Prediction of electric field impact on residential houses is required in the design of UHVDC transmission lines.The calculation of electric field distribution on houses is a 3D problem,however,the effectiveness of som...Prediction of electric field impact on residential houses is required in the design of UHVDC transmission lines.The calculation of electric field distribution on houses is a 3D problem,however,the effectiveness of some 2D calculation meth-ods has been validated by specific reduced-scale experimental models.The 2D methods are simple in operation and quick in computation compared with the 3D methods.In this paper,the deviation ranges of 2D electric field calculation results on houses are discussed.Then,a 3D electric field reconstruction method is proposed to correct the 2D results according to the size and location of the houses.The 3D electric field distribution on the houses can be obtained based on efficient 2D calculations,and a direct 3D calculation is avoided.Finally,the validity of the calculation methods is verified by the measurement results of a full-scale experimental system.展开更多
Based on block copolymer assisted topochemical polymerization,a new strategy for facilely producing robust nanoporous membranes with controlled incorporation of functional groups onto nanopores is developed.As exempli...Based on block copolymer assisted topochemical polymerization,a new strategy for facilely producing robust nanoporous membranes with controlled incorporation of functional groups onto nanopores is developed.As exemplified by preparing nanoporous polypyrrole decorated with amino acids,this strategy exhibits a high degree of freedom for tailoring the surface functionality in the created pores.展开更多
A new oleanolic acid derivative with A-ring lactone,C-ring rearrangement and decarboxylation at C28 was synthesized,which was confirmed by HRMS,NMR and X-ray crystal structure.It is the first report about the methyl r...A new oleanolic acid derivative with A-ring lactone,C-ring rearrangement and decarboxylation at C28 was synthesized,which was confirmed by HRMS,NMR and X-ray crystal structure.It is the first report about the methyl rearrangement on C-ring of oleanolic phenylmethyl ester,and the possible mechanism was proposed as the 1,2-methyl shift.展开更多
Ground total electric field(GTEF)is a vital parameter in the field of electromagnetic environment of high voltage direct current(HVDC)lines.Some experimental works re-ported that airborne suspended particles can be ch...Ground total electric field(GTEF)is a vital parameter in the field of electromagnetic environment of high voltage direct current(HVDC)lines.Some experimental works re-ported that airborne suspended particles can be charged in the corona ion flow of the lines and thus affect GTEF.This paper aims at studying the charging models for particles.Equivalent unipolar charging models(EUCMs)and bipolar charging models(BCMs)for describing field and diffusion charging mechanisms in bipolar ion environments are introduced and the Maxwell-Wagner relaxation is proposed to be incorporated.Besides,the EUCMs and BCMs are analysed and validated through comparisons with experimental data.The results show that BCMs are applicable to describing the particle charging in a bipolar ion environment,while EUCMs are not.The predictions made by BCM that takes into account the Maxwell-Wagner relaxation are in good agreement with experimental results.Moreover,the BCMs are proposed to analyse the experimental results about GTEF in the presence of particles,which are not understood before.It is demonstrated that the BCMs are able to qualitatively explain these results.Finally yet importantly,a new charging model combining field and diffusion charging mechanism is proposed for airborne suspended particles around HVDC lines and validated by experiments.The results show that the proposed hybrid field-diffusion charging model is able to give predictions consistent with experiments.展开更多
基金The authors would like to thank the financial supports from the NNSF of China(No.201 72033),the Ministry of Science and Technology,the Ministry of Education and Tsinghua University.
文摘The a-L-rhamnopyranosyl phosphomonoesters conjugated with L-amino acid methyl esters were stereoselectively synthesized in a convenient route by utilizing H-phosphonate intermediate.
基金Project supported by the Nahonal Natural Sciencc Foundahon and the grant for doctoral program from State Education Commission of China
文摘Two new minor steroidal saponins, (25R) spirostan-3β-ol-6-one-3-O-[α-L- arabinopyranosyl(1-4)]-β-D-glucopyranosidc (1) and (25S) spirost-5-en -3β, 17α, 27-triol-3-O- [α-L-arabinopyranosyl(1-6)]-β-D-glucopyranosidc (2) were isolated from the roots of Smilax lebrunii. Their structures were established on thc basis of chemical and spectral methods.
文摘The reaction between D-glucose, D-ribose and 2, 2,2-trimethoxy-4, 5-diphenyl-2, 2-dihydro-1, 3, 2-dioxaphospholene were investigates by P-31 NMR and FAB-MS. The results showed that there were a lot of differences in the reactions via pentacoordinate phosphorus compound, and it should give it significant clue to the metabolism of carbohydrate phosphate in nature.
文摘In order to further confirm the biomimic properties of N-phosphoamino acids. A series of model compounds, analogue of phosphoryl amino acids, were synthesized and their biomimic mechanism was also investigated by NMR and MS methods. The results indicated that the reactivity of phosphoryl biological small molecules was depended on the configuration, function groups and positions.
文摘A new compound. methyl 4. 6-O-benzylidene-a-D-glucopyranoside 2. 3-cyclicphosphite ethyl ester was synthesized via the reaction of methyl 4. 6-O-benzylidene-a-D-glucopyranoside and ethyl dichlorophosphite. Its structure was confirmed by NMR and MSspectral methods.
基金This work was supported bythe National Natural Science Foundation (No .60174005) Natural Science Foundation of Jiangsu Province (No .BK2001054) .
文摘Based on the stability theory of linear time-varying continuous system, this paper investigates the synchronization of two linear bidirectionally-coupled systems. Sufficient conditions for asymptotic synchronization are obtained for general chaotic system with bidirectional coupling via linear error feedback. Since the trajectory of chaotic system is continuous and bounded, one can choose suitable coupled pararneters to satisfy the proposed criterion. The criterion can also be applied to the global synchronization for chaotic systems with linear unidirectional coupling. The chaotic Chen system and the generalized Lorenz-like system are taken as examples, the simulations verify the effectiveness of the proposed method.
文摘A New steroidal saponin was isolated from the rhizomes of Smilax lebrunii. On the basis of spectral and chemical methods, its structure was elucidated as:(25S)spirost-5-en-3β, 17α, 27-triol-3-0-[β-D-glucopyranosyl(1-4)][α-L-arabinopyranosyl(1-6)]-β-D-glucopyranoside.
文摘Oxyphosphorane reacted with glucose to give disaccharide which was confirmed by FAB-MS and C-13-NMR. The mechanism for formation of oligosaccharides through the participation of phosphorus was proposed.
基金Project supported by the National Natural Scicnce Foundation of Chinathe grant for doctoral program from State Education Commission of China
文摘Two minor steroidal saponins were isolated from the roots of Smilax menispermoidea.One of them is new and its structure was established as(25S) spirost-5-en-3β,17α,27-triol-3-O-[α-L-rhamnopyranosyl(1-4)]-β-D-gluco- pyranoside using spectroscopic and chemical methods.
文摘In the presence of phosphoryl group, N-diisopropyloxy phosphoryl amino ac ids become more reactive and undergo self-catalys is to farm the peptides by coupling with amino acids or their esters in aqueous solution at low temperature. The different side chain amino acid would appear with different reactivity. It might be important for the prebiotic synthesis of protein.
基金This work was supported in part by National Key Research and Development Program under Grant 2016YFB0900900in part by State Grid Corporation of China under Project GY71-18-008.
文摘Prediction of electric field impact on residential houses is required in the design of UHVDC transmission lines.The calculation of electric field distribution on houses is a 3D problem,however,the effectiveness of some 2D calculation meth-ods has been validated by specific reduced-scale experimental models.The 2D methods are simple in operation and quick in computation compared with the 3D methods.In this paper,the deviation ranges of 2D electric field calculation results on houses are discussed.Then,a 3D electric field reconstruction method is proposed to correct the 2D results according to the size and location of the houses.The 3D electric field distribution on the houses can be obtained based on efficient 2D calculations,and a direct 3D calculation is avoided.Finally,the validity of the calculation methods is verified by the measurement results of a full-scale experimental system.
基金financial support from the Ministry of Science and Technology of the People's Republic of China(MOST,Nos.2017YFA0204501,2013CB834502)National Natural Science Foundation of China(NSFC,Nos.21773135,21473098 and 21421064)。
文摘Based on block copolymer assisted topochemical polymerization,a new strategy for facilely producing robust nanoporous membranes with controlled incorporation of functional groups onto nanopores is developed.As exemplified by preparing nanoporous polypyrrole decorated with amino acids,this strategy exhibits a high degree of freedom for tailoring the surface functionality in the created pores.
基金The project was supported by NSFC(No.21172130)and NBRPC(973 Program,No.2012CB821600).
文摘A new oleanolic acid derivative with A-ring lactone,C-ring rearrangement and decarboxylation at C28 was synthesized,which was confirmed by HRMS,NMR and X-ray crystal structure.It is the first report about the methyl rearrangement on C-ring of oleanolic phenylmethyl ester,and the possible mechanism was proposed as the 1,2-methyl shift.
基金State Grid Corporation of China,Grant/Award Number:52010118001P。
文摘Ground total electric field(GTEF)is a vital parameter in the field of electromagnetic environment of high voltage direct current(HVDC)lines.Some experimental works re-ported that airborne suspended particles can be charged in the corona ion flow of the lines and thus affect GTEF.This paper aims at studying the charging models for particles.Equivalent unipolar charging models(EUCMs)and bipolar charging models(BCMs)for describing field and diffusion charging mechanisms in bipolar ion environments are introduced and the Maxwell-Wagner relaxation is proposed to be incorporated.Besides,the EUCMs and BCMs are analysed and validated through comparisons with experimental data.The results show that BCMs are applicable to describing the particle charging in a bipolar ion environment,while EUCMs are not.The predictions made by BCM that takes into account the Maxwell-Wagner relaxation are in good agreement with experimental results.Moreover,the BCMs are proposed to analyse the experimental results about GTEF in the presence of particles,which are not understood before.It is demonstrated that the BCMs are able to qualitatively explain these results.Finally yet importantly,a new charging model combining field and diffusion charging mechanism is proposed for airborne suspended particles around HVDC lines and validated by experiments.The results show that the proposed hybrid field-diffusion charging model is able to give predictions consistent with experiments.
