The intrinsic viscosity and viscometric interaction parameters of perfluorosulfonic acid （PFSA） and poly（vinyl alcohol） （PVA） were measured by dilute solution viscometry. The miscibility between PFSA and PVA was...The intrinsic viscosity and viscometric interaction parameters of perfluorosulfonic acid （PFSA） and poly（vinyl alcohol） （PVA） were measured by dilute solution viscometry. The miscibility between PFSA and PVA was estimated by the criteria of AB and μ. The results indicated that PFSA and PVA were completely miscible for any weight fraction in aqueous solution.展开更多
The perfluorosulfonic acid （PFSA）/SiO2 composite catalysts were prepared by sol-gel method. Differences concerning pore structure analysis of PFSA/SiO2 catalysts were discussed on the basis of nitrogen adsorption. T...The perfluorosulfonic acid （PFSA）/SiO2 composite catalysts were prepared by sol-gel method. Differences concerning pore structure analysis of PFSA/SiO2 catalysts were discussed on the basis of nitrogen adsorption. Their surface area and pore size distributions were evaluated by Brunauer-Emmett-Teller （BET） and Barrett-Joyner-Halenda （BJH） methods, respectively. The nitrogen adsorption-desorption isotherms associated with adsorption hysteresis of PFSA/SiO2 catalysts were analyzed in detail. The adsorption isotherms of PFSA/SiOe catalysts belonged to Type IV isotherms accompanied by hysteresis loops of Type H1 for PFSA/SiO2 catalysts with content of 5%, 13% and 20% PFSA （PFSA-5, PFSA-13 and PFSA-20）, and the hysteresis loop of Type H2 for PFSA/SiO2 catalyst with 40% PFSA content （PFSA-40）. It indicated that PFSA-5, PFSA-13 and PFSA-20 catalysts had narrow pore size distributions and the well-defined cylindrical pores, while PFSA-40 catalyst had wide pore size distribution and inkbottle-like pores. The pore structure of PFSA-40 catalyst from the analysis of the hysteresis loop was not in agreement with that from BJH method. As an emendation for evaluation of pore size distributions of PFSA/SiOz catalysts, the comparison plots method was introduced, which was helpful to evaluate the pore structure of PFSA/SiO2 catalysts more factually.展开更多
Perfluorosulfonic acid/Polysulfone(PFSA/PSf) hollow fiber composite membranes have been prepared by dip-coating method using PSf ultrafiltration(UF) membrane as substrate with recovered PFSA.The composite membranes we...Perfluorosulfonic acid/Polysulfone(PFSA/PSf) hollow fiber composite membranes have been prepared by dip-coating method using PSf ultrafiltration(UF) membrane as substrate with recovered PFSA.The composite membranes were applied to the pervaporation separation of 95% ethanol(EtOH)/H2O mixture.SEM images show that the thickness of the PFSA skin layer of the composite membranes is about 2 μm,much thinner than those of other PFSA composite membranes revealed in the literatures.Effects of annealing temperature,coating solution concentration and counter-ions of PFSA on the pervaporation performances of the composite membranes were investigated.The total flux decreases and separation factor increases with the increase of annealing temperature.The highest permeation flux of 3230 g m-2 h-1 and a separation factor of 5.4 is obtained for the composite membrane annealed at 80°C.The lowest permeation flux of 396 g m-2 h-1 and a separation factor of 27.7 is obtained for the composite membrane annealed at 160°C.The permeation performances of the PFSA/PSf composite membrane are evidently influenced by the counter-ions of PFSA.The flux sequence of the PFSA/PSf composite membranes with different counter-ions is H+】Li+】Ca2+】Mg2+】Na+】K+】Ba2+】Fe3+】Al3+,and the separation factor sequence is H+【Li+【Al3+【Na+【Mg2+【Ca2+【K+ 【Ba2+【Fe3+.The apparent activation energy △Eapp values of the composite membranes with different counter-ions were calculated by Arrhenius law.The sequence of △Eapp values for the membranes with monovalent counter-ions is Li+】Na+】K+.There are very little variations of △Eapp values between the composite membranes with three divalent counterions(Mg2+,Ca2+ and Ba2+),and the △Eapp values of the composite membranes with two trivalent counterions(Fe3+ and Al3+) are relatively high.展开更多
分析了无结构对等网络若干经典搜索算法的优缺点,进而提出一种兼顾查询深度与广度的平台搜索算法(PFSA:P latform Search ing A lgorithm)。该算法在提高了网络资源利用率、保持较快搜索速度的同时维持着较低的消息冗余度;其子查询算法...分析了无结构对等网络若干经典搜索算法的优缺点,进而提出一种兼顾查询深度与广度的平台搜索算法(PFSA:P latform Search ing A lgorithm)。该算法在提高了网络资源利用率、保持较快搜索速度的同时维持着较低的消息冗余度;其子查询算法针对B lind Counter RumorMongering算法的不足加以改进,使得搜索算法可以根据不同的网络动态地调整自身参数,大大提高了算法的鲁棒性。展开更多
The performance of proton exchange membrane fuel cells (PEMFC) is strongly determined by the structure and composition of the electrode layer.The interactions between the ionomer,carbon black particles,and solvent aff...The performance of proton exchange membrane fuel cells (PEMFC) is strongly determined by the structure and composition of the electrode layer.The interactions between the ionomer,carbon black particles,and solvent affect the suspension properties and thus the layer morphology.We analyze the effect of the ionomer-to-carbon (I/C) weight ratio for two different types of carbon black on the suspension and layer characteristics.Highly branched carbon blacks with a high surface area tend to form less cracked layers.As less branched carbons can pack together more closely,a smaller pore size results in a larger capillary pressure during drying and thus more cracks.The added ionomer adsorbs on the carbon particles and improves the colloidal stability of the carbon black particles.The carbon black aggregates are thus smaller,resulting in closer packing and thinner layers.Moreover,the addition of the ionomer increases the critical coating thickness (CCT) of the layers because drying stresses are dissipated by the deformation of the ionomer,preventing crack formation.An optimum I/C weight ratio is identified for optimal layer formation and minimized crack formation.展开更多
We used a new approach,protein folding shape code（PFSC）,to predict the potential staurosporine binding sites in protein kinases.Firstly,all available three dimensioned（3D） structures of protein kinases in protein ...We used a new approach,protein folding shape code（PFSC）,to predict the potential staurosporine binding sites in protein kinases.Firstly,all available three dimensioned（3D） structures of protein kinases in protein databank（PDB） were converted into one-dimensional PFSC description,based on which a PFSC-kinome library was constructed.Secondly,a set of protein kinase-staurosporine complexes were analyzed to define the common structural features of the binding sites.Thirdly,the structural features of the staurosporine binding sites were used to virtually screen the PFSC-kinome library to predict multiple protein receptors that have potential binding capacity for staurosporine.Collectively,the development of the similar method for predicting drug binding site demonstrates that virtual screening protein database can provide valuable information on drug discovery and understanding of pharmacological pathways.展开更多
基金supported by the Innovation Program of Shanghai Municipal Education Commission (Grant No.09YZ163)
文摘The intrinsic viscosity and viscometric interaction parameters of perfluorosulfonic acid （PFSA） and poly（vinyl alcohol） （PVA） were measured by dilute solution viscometry. The miscibility between PFSA and PVA was estimated by the criteria of AB and μ. The results indicated that PFSA and PVA were completely miscible for any weight fraction in aqueous solution.
基金supported by the National Basic Research Program of China (2003CB615705)Chemistry & Chemical Technology Research Center Plan of Shanghai Huayi Group Company (A200-8608 and A200-80726)
文摘The perfluorosulfonic acid （PFSA）/SiO2 composite catalysts were prepared by sol-gel method. Differences concerning pore structure analysis of PFSA/SiO2 catalysts were discussed on the basis of nitrogen adsorption. Their surface area and pore size distributions were evaluated by Brunauer-Emmett-Teller （BET） and Barrett-Joyner-Halenda （BJH） methods, respectively. The nitrogen adsorption-desorption isotherms associated with adsorption hysteresis of PFSA/SiO2 catalysts were analyzed in detail. The adsorption isotherms of PFSA/SiOe catalysts belonged to Type IV isotherms accompanied by hysteresis loops of Type H1 for PFSA/SiO2 catalysts with content of 5%, 13% and 20% PFSA （PFSA-5, PFSA-13 and PFSA-20）, and the hysteresis loop of Type H2 for PFSA/SiO2 catalyst with 40% PFSA content （PFSA-40）. It indicated that PFSA-5, PFSA-13 and PFSA-20 catalysts had narrow pore size distributions and the well-defined cylindrical pores, while PFSA-40 catalyst had wide pore size distribution and inkbottle-like pores. The pore structure of PFSA-40 catalyst from the analysis of the hysteresis loop was not in agreement with that from BJH method. As an emendation for evaluation of pore size distributions of PFSA/SiOz catalysts, the comparison plots method was introduced, which was helpful to evaluate the pore structure of PFSA/SiO2 catalysts more factually.
基金supported by the Leading Academic Discipline Project of SHNU (No.DZL807)Innovation Program of Shanghai Municipal Education Commission (No.09YZ163)Shanghai Municipal Natural Science Foundation (No.09ZR1423300)
文摘Perfluorosulfonic acid/Polysulfone(PFSA/PSf) hollow fiber composite membranes have been prepared by dip-coating method using PSf ultrafiltration(UF) membrane as substrate with recovered PFSA.The composite membranes were applied to the pervaporation separation of 95% ethanol(EtOH)/H2O mixture.SEM images show that the thickness of the PFSA skin layer of the composite membranes is about 2 μm,much thinner than those of other PFSA composite membranes revealed in the literatures.Effects of annealing temperature,coating solution concentration and counter-ions of PFSA on the pervaporation performances of the composite membranes were investigated.The total flux decreases and separation factor increases with the increase of annealing temperature.The highest permeation flux of 3230 g m-2 h-1 and a separation factor of 5.4 is obtained for the composite membrane annealed at 80°C.The lowest permeation flux of 396 g m-2 h-1 and a separation factor of 27.7 is obtained for the composite membrane annealed at 160°C.The permeation performances of the PFSA/PSf composite membrane are evidently influenced by the counter-ions of PFSA.The flux sequence of the PFSA/PSf composite membranes with different counter-ions is H+】Li+】Ca2+】Mg2+】Na+】K+】Ba2+】Fe3+】Al3+,and the separation factor sequence is H+【Li+【Al3+【Na+【Mg2+【Ca2+【K+ 【Ba2+【Fe3+.The apparent activation energy △Eapp values of the composite membranes with different counter-ions were calculated by Arrhenius law.The sequence of △Eapp values for the membranes with monovalent counter-ions is Li+】Na+】K+.There are very little variations of △Eapp values between the composite membranes with three divalent counterions(Mg2+,Ca2+ and Ba2+),and the △Eapp values of the composite membranes with two trivalent counterions(Fe3+ and Al3+) are relatively high.
文摘分析了无结构对等网络若干经典搜索算法的优缺点,进而提出一种兼顾查询深度与广度的平台搜索算法(PFSA:P latform Search ing A lgorithm)。该算法在提高了网络资源利用率、保持较快搜索速度的同时维持着较低的消息冗余度;其子查询算法针对B lind Counter RumorMongering算法的不足加以改进,使得搜索算法可以根据不同的网络动态地调整自身参数,大大提高了算法的鲁棒性。
文摘The performance of proton exchange membrane fuel cells (PEMFC) is strongly determined by the structure and composition of the electrode layer.The interactions between the ionomer,carbon black particles,and solvent affect the suspension properties and thus the layer morphology.We analyze the effect of the ionomer-to-carbon (I/C) weight ratio for two different types of carbon black on the suspension and layer characteristics.Highly branched carbon blacks with a high surface area tend to form less cracked layers.As less branched carbons can pack together more closely,a smaller pore size results in a larger capillary pressure during drying and thus more cracks.The added ionomer adsorbs on the carbon particles and improves the colloidal stability of the carbon black particles.The carbon black aggregates are thus smaller,resulting in closer packing and thinner layers.Moreover,the addition of the ionomer increases the critical coating thickness (CCT) of the layers because drying stresses are dissipated by the deformation of the ionomer,preventing crack formation.An optimum I/C weight ratio is identified for optimal layer formation and minimized crack formation.
基金Supported by the National Natural Science Foundation of China（Nos.20771030, 20671025）.Acknowledgements We are thankful to HAN Weiwei and WANG Ye in the Key Laboratory for Molecular Enzymology and Engineering of the Ministry of Education, Jilin University for assistance in using the computational facilities.
文摘We used a new approach,protein folding shape code（PFSC）,to predict the potential staurosporine binding sites in protein kinases.Firstly,all available three dimensioned（3D） structures of protein kinases in protein databank（PDB） were converted into one-dimensional PFSC description,based on which a PFSC-kinome library was constructed.Secondly,a set of protein kinase-staurosporine complexes were analyzed to define the common structural features of the binding sites.Thirdly,the structural features of the staurosporine binding sites were used to virtually screen the PFSC-kinome library to predict multiple protein receptors that have potential binding capacity for staurosporine.Collectively,the development of the similar method for predicting drug binding site demonstrates that virtual screening protein database can provide valuable information on drug discovery and understanding of pharmacological pathways.
