In order to explore the effect mechanism of solvent on the synthesis of the metal organic framework materials, the microscopic interaction between solvent and framework and the effects of N,N-dimethyl-formamide(DMF) o...In order to explore the effect mechanism of solvent on the synthesis of the metal organic framework materials, the microscopic interaction between solvent and framework and the effects of N,N-dimethyl-formamide(DMF) or N-methyl- 2-pyrrolidone(NMP) on solvothermal synthesis of [Zn4O(BDC)3]8 were investigated through a combined DFT and experimental study. XRD and SEM showed that the absorbability of NMP in the pore of [Zn4O(BDC)3]8 was weaker than that of DMF. The thermal decomposition temperature of [Zn4O(BDC)3]8 synthesized in DMF was higher than that in NMP according to TG and FT-IR. In addition, the nitrogen sorption isotherms indicated that NMP improved gas sorption property of [Zn4O(BDC)3]8. The COSMO optimized calculations indicated that the total energy of Zn4O(BDC)3 in NMP was higher than that in DMF, and compared with non-solvent system, the charge of zinc atoms decreased and the charge value was the smallest in NMP. Furthermore, the interaction of DMF, NMP or DEF in [Zn4O(BDC)3]8 crystal model was calculated by DFT method. The results suggested that NMP should be easier to be removed from pore of materials than DMF from the point of view of energy state. It can be concluded that NMP was a favorable solvent to synthesize [Zn4O(BDC)3]8 and the microscopic mechanism was that the binding force between Zn4O(BDC)3 and NMP molecule was weaker than DMF.展开更多
The content and the caking index of the heavy,the dense medium and the loose medium components of coal,obtained by extraction and stripping with CS_2/N-methyl-2-pyrrolidinone mixed solvent(1:1 by volume),were studied ...The content and the caking index of the heavy,the dense medium and the loose medium components of coal,obtained by extraction and stripping with CS_2/N-methyl-2-pyrrolidinone mixed solvent(1:1 by volume),were studied and correlated with the caking property of raw coals.Images of the three group components after heat treatment were analyzed.The results show that both caking index(G) and maximum thickness of plastic layer(Y) of coals have a good linear relationship with the content of the medium component;the dense medium and the loose medium components are the two key factors to determine the caking property of raw coals-they are the source materials of fluidity and swelling of coal,respectively;the heavy component without the swelling and fluidity was cohered by the other components;two new indexes,which can extend current understanding of the caking properties,were introduced.展开更多
Terephthalic acid(PTA) is practically one of the main materials of polyester. Its corresponding solid-liquid equilibrium data will provide essential support for industry design and further theoretical studies. In this...Terephthalic acid(PTA) is practically one of the main materials of polyester. Its corresponding solid-liquid equilibrium data will provide essential support for industry design and further theoretical studies. In this work,solid-liquid equilibriums of terephthalic acid in four solvents, N,N-dimethylformamide, N,N-dimethylacetamide,dimethylsulphoxide and N-methyl-2-ketopyrrolidene, were determined in the temperature range from 293.15 K to 364.6 K by dynamic method. All these data were regressed by λh model, Wilson model and NRTL model, average absolute relative deviations of which are 1.25%, 15.02% and 7.22% respectively. It indicates that λh model is mostsuitable for description of the solid-liquid equilibrium containing PTA.展开更多
Poly(p-phenylene terephthalamide)(PPTA)pulp was prepared by polycondensation of the p-phenylene diamine(PPDA)with terephthaloyl chloride(TPC)in the completely anhydrous solvent system of N-methyl pyrrolidone(NMP)havin...Poly(p-phenylene terephthalamide)(PPTA)pulp was prepared by polycondensation of the p-phenylene diamine(PPDA)with terephthaloyl chloride(TPC)in the completely anhydrous solvent system of N-methyl pyrrolidone(NMP)having calcium chloride,in the presence of poly(vinyl pyrrolidone)(PVP)having a viscosity average molecular weight lower than 40 000.It was confirmed that the polycondensation could be accelerated,the inherent viscosity of the polymer could be increased,and the polymers could be fibrillated more easily by the addition of the PVP.FTIR and X-ray spectra proved that PVP had not combined into molecular chains of the resultant PPTA pulps.The morphology of the resultant pulps,the effect of viscosity average molecular weight,amount and adding mode of PVP on inherent viscosity,specific surface area,and mean length of the resultant pulps were discussed in detail.And the friction and wear properties of the compound reinforced by the resultant pulps were simply investigated.展开更多
Improvement of coking properties of sub-bituminous coal (A) and bituminous coal (B) was done using blended organic solvents, namely, n-methyl-2-pyrrolidinone (NMP) and ethylenediamine (EDA). Various solvent bl...Improvement of coking properties of sub-bituminous coal (A) and bituminous coal (B) was done using blended organic solvents, namely, n-methyl-2-pyrrolidinone (NMP) and ethylenediamine (EDA). Various solvent blends were employed for the coal extraction under the total reflux condition. A low-cost ceramic membrane was fabricated using industrial waste iron ore slime of M/s TATA steel R&D, Jamshedpur (India) to separate out the dissolved coking fraction from the solvent-coal mixture. Membrane separations were carried out in a batch cell, and around 75 % recovered NMP was reused. The fractionated coal properties were determined using proximate and ultimate analyses. In the case of bituminous coal, the ash and sulfur contents were decreased by 99.3 % and 79.2 %, respectively, whereas, the carbon content was increased by 23.9 % in the separated coal fraction. Three different cleaning agents, namely deionized water, sodium dodecyl sulphate and NMP were used to regain the original membrane permeability for the reusing.展开更多
Catalyst plays an important role in the dehydration of N-(hydroxylethyl)pyrrolidone (NHP) to prepare N-vinyl-pyrrolidone (NVP). At present, NVP yield is only about 30% on commercial ZrO2 catalyst. A coupled prec...Catalyst plays an important role in the dehydration of N-(hydroxylethyl)pyrrolidone (NHP) to prepare N-vinyl-pyrrolidone (NVP). At present, NVP yield is only about 30% on commercial ZrO2 catalyst. A coupled precipitation and solid dispersion technique was designed to prepare the nano-ZrO2 catalyst, in which rare earth metal oxides (REOx) was used as electronic promoter. The results indicated that the catalyst doped REOx (S-1.0) exhibits the optimum performance of NHP dehydration at moderate conditions. NHP conversion and NVP selectivity are respectively 97.0%, 82.3%. Of special interest is that the indexes of the catalyst (S-1.0-1.0) are up to 98.4% and 89.2% respectively. Furthermore, this catalyst bears the good stability. It means that nano-ZrO2 doped REOx catalyst might be a potential commercial catalyst for the NHP dehydration.展开更多
Kinetics of copolymerization of acrylonitrile(AN) with N-vinylpyrrolidone(NVP) initiated by azodi-isobutyronitrile(AIBN) was investigated in H2O/dimethyl sulphoxide(DMSO) mixture between 50℃ and 70℃ under N2 atmosph...Kinetics of copolymerization of acrylonitrile(AN) with N-vinylpyrrolidone(NVP) initiated by azodi-isobutyronitrile(AIBN) was investigated in H2O/dimethyl sulphoxide(DMSO) mixture between 50℃ and 70℃ under N2 atmosphere. The rate of copolymerization and particle size were measured respectively. The kinetic equation of copolymerization system is obtained as Rpat 60℃. The overall activation energy for copolymerization system was computed as 87.3kJ.mol-1. Effect of additives of hydroquinone and dioxane on copolymerization was discussed. The polymerization is retarded by hydroquinone and accelerated by dioxane, which confirms the free radical copolymerization of AN with NVP.展开更多
With N-vinyl-2-pyrrolidone (NVP) and itaconic acid(IA), poly(N-vinyl-2-pyrrolidone/itaconic acid)[P(NVP/IA)] hydrogel was synthesized by free radical solution polymerization. The structure of this (P(NVP/IA)) was char...With N-vinyl-2-pyrrolidone (NVP) and itaconic acid(IA), poly(N-vinyl-2-pyrrolidone/itaconic acid)[P(NVP/IA)] hydrogel was synthesized by free radical solution polymerization. The structure of this (P(NVP/IA)) was characterized by IR. Effects of concentration of itaconic acid, amount of cross-link agent, N,N′-methylene-bis-acrylamide, reaction temperature, and time on properties of swelling ratio(SR) of the hydrogel were investigated.The results show that the best swelling property of the hydrogel is obtained at 50 ℃ and 1.5 h. pH sensitivity increases as the concentration of itaconic acid in the hydrogel system increases. Swelling ratio of the hydrogel decreases as the amount of cross-link agent increases.展开更多
Nano-silver/polyvinylpyrrolidone(PVP)composite materials were successfully synthesized bi-insitu from silver nitrate solution with N-vinyl pyrrolidone (NVP) monomer,containing neither initiator nor reductant, in ultra...Nano-silver/polyvinylpyrrolidone(PVP)composite materials were successfully synthesized bi-insitu from silver nitrate solution with N-vinyl pyrrolidone (NVP) monomer,containing neither initiator nor reductant, in ultraviolet irradiation conditions.The resultant Ag/PVP nanocomposites were characterized by infrared spectroscopy (FT-IR), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD).TEM show that nano silver particles are homogeneously dispersed in PVP polymer matrix, and the mean size of spherical silver particles is about 5 nm.The spectroscopy of XPS and FTIR showed that there is an interaction between nano silver not only with carbonyl oxygen but also with the nitrogen group within the NVP molecule through the p-π conjugation effect in the nano-silver/PVP composites system.展开更多
The crystal structure of the title compound UO2(NO3)2[CH2(CH2)2CONC8H17] was determined by single-crystal X-ray diffraction. Crystal data: triclinic, space group P , a = 7.456(2), b = 8.371(2), c = 13.470(3) ? ?= 95.6...The crystal structure of the title compound UO2(NO3)2[CH2(CH2)2CONC8H17] was determined by single-crystal X-ray diffraction. Crystal data: triclinic, space group P , a = 7.456(2), b = 8.371(2), c = 13.470(3) ? ?= 95.66(1), ?= 94.64(2), ?= 102.67(2), C24H46N4O10U, Mr = 788.68, V = 811.7(3) ?, Dc = 1.613 g/cm3, Z = 1, F(000) = 390, ?= 5.052 mm-1, the final R = 0.0256 and wR = 0.0568 for 2826 observed reflections (I > 2(I)). The central uranyl ions are coordinated by six oxygen atoms. Two of them are from the carbonyl groups of N-octyl-a-pyrrolidone molecules, and the other four from two nitrate groups.展开更多
The mass spectrometry of gold clusters stabilized by poly(N‐vinyl‐2‐pyrrolidone) (Au:PVP) re‐vealed the presence of Cl adsorbates derived from synthetic precursors, mainly on the Au34 and Au43 clusters. Chang...The mass spectrometry of gold clusters stabilized by poly(N‐vinyl‐2‐pyrrolidone) (Au:PVP) re‐vealed the presence of Cl adsorbates derived from synthetic precursors, mainly on the Au34 and Au43 clusters. Changes in the amount of Cl adsorbates on the Au clusters did not affect the catalytic prop‐erties for the aerobic oxidation of benzyl alcohol, suggesting that the Cl atoms were only weakly bound to the Au clusters. In contrast, the replacement of Cl with Br on the Au34 and Au43 clusters significantly suppressed activity, without any influence on the electronic structure. This result indi‐cated that the Br atoms were strongly bound to the Au clusters and sterically blocked their active sites. The substantial reduction of the catalytic activity by the Br adsorbates suggested that the Au34 and Au43 clusters made a major contribution to the catalytic activity of the Au:PVP.展开更多
High dispersed carbon black was applied for LiFePO4 cathodes as conductive agent.Nano-conductive carbon agent was pre-dispersed with poly acrylic acid(PAA) as dispersant in organic N-methyl-pyrrolidone(NMP) solvent sy...High dispersed carbon black was applied for LiFePO4 cathodes as conductive agent.Nano-conductive carbon agent was pre-dispersed with poly acrylic acid(PAA) as dispersant in organic N-methyl-pyrrolidone(NMP) solvent system.The dispersion property of nano-conductive carbon agent was evaluated using particle size distribution measurements,scanning electron microscopy(SEM) and transmission electron microscope(TEM).LiFePO4 cathode with as-received nano-conductive carbon agent(SP) and LiFePO4 cathode with pre-dispersed nano-conductive carbon agent(SP-PAA) were examined by scanning electron microscopy(SEM),cyclic voltammetry(CV),electrochemical impendence spectroscopy(EIS) and charge/discharge cycling performance.Results show that the dispersion property of carbon black is improved by using PAA as the dispersant.The LiFePO4 cathodes with SP-PAA exhibit improved rate behaviors(4C,135.1 mAh/g) and cycle performance(95%,200 cycles) compared to LiFePO4 cathodes with SP(4C,103.9 mAh/g and 83%,200 cycles).Because pre-dispersed carbon black(SP-PAA) is dispersed homogeneously in the dried composite electrode to form a more uniform conductive network between the active material particles,electrochemical performances of the LiFePO4 cathodes are improved.展开更多
In this study, the polyacrylate intraocularr lens is irradiated by argon ion which can produce free radicals. In order to obtain better hydrophilic and lower platelets adhesion, monomer vinyl pyrrolidone (NVP) is graf...In this study, the polyacrylate intraocularr lens is irradiated by argon ion which can produce free radicals. In order to obtain better hydrophilic and lower platelets adhesion, monomer vinyl pyrrolidone (NVP) is grafted onto the hydrophobic polyacrylate intraocular lens surface in a certain reaction conditions. Specific changes in intraocular lens are detected by static contact angle (CA), scanning electron microscope (SEM) and light transmittance. The results show that this surface modification can greatly improve its hydrophilic character and surface formation.展开更多
Experimental data on density and viscosity at 303.15K and 323.15K are presented for the binary mixtures of p-xylene with cyclohexane, n-heptane, n-octane, sulfolane, N-methyl-2-pyrrolidone and acetic acid.From these d...Experimental data on density and viscosity at 303.15K and 323.15K are presented for the binary mixtures of p-xylene with cyclohexane, n-heptane, n-octane, sulfolane, N-methyl-2-pyrrolidone and acetic acid.From these data, the excess molar volume and deviations in viscosity have been calculated. The computed quantities have been fitted to the Redlich-Kister Equation to derive coefficients and estimate the standard error values. Results are discussed in terms of intermolecular interactions.展开更多
Monophasic mullite gel with composition 3Al2O3·2SiO2 was prepared by the sol-gel method using aluminium nitrate nonahydrate, aluminium-tri-isopropoxide, and tetraethylorthosili-cate as reagents. Gels with differe...Monophasic mullite gel with composition 3Al2O3·2SiO2 was prepared by the sol-gel method using aluminium nitrate nonahydrate, aluminium-tri-isopropoxide, and tetraethylorthosili-cate as reagents. Gels with different drying control chemical additives(DCCAs) and polyvinylpyrrolidone(PVP) as spinning assistant were dried at several temperatures. The influences of temperature, DCCAs and PVP in the drying process were investigated. N,N-dimethylformamide(DMF) was the optimum DCCA at 70℃ in the drying process. PVP decreased the solvent volatilization speed and prevented gel crack to a certain extent. FTIR results revealed that free water, ethanol, and isopropanol were completely removed by the drying procedure.展开更多
基金Project(51104185)supported by the National Natural Science Foundation of ChinaProject(2010QZZD003)supported by the Key Project of Central South University of Fundamental Research Funds for the Central Universities of China
文摘In order to explore the effect mechanism of solvent on the synthesis of the metal organic framework materials, the microscopic interaction between solvent and framework and the effects of N,N-dimethyl-formamide(DMF) or N-methyl- 2-pyrrolidone(NMP) on solvothermal synthesis of [Zn4O(BDC)3]8 were investigated through a combined DFT and experimental study. XRD and SEM showed that the absorbability of NMP in the pore of [Zn4O(BDC)3]8 was weaker than that of DMF. The thermal decomposition temperature of [Zn4O(BDC)3]8 synthesized in DMF was higher than that in NMP according to TG and FT-IR. In addition, the nitrogen sorption isotherms indicated that NMP improved gas sorption property of [Zn4O(BDC)3]8. The COSMO optimized calculations indicated that the total energy of Zn4O(BDC)3 in NMP was higher than that in DMF, and compared with non-solvent system, the charge of zinc atoms decreased and the charge value was the smallest in NMP. Furthermore, the interaction of DMF, NMP or DEF in [Zn4O(BDC)3]8 crystal model was calculated by DFT method. The results suggested that NMP should be easier to be removed from pore of materials than DMF from the point of view of energy state. It can be concluded that NMP was a favorable solvent to synthesize [Zn4O(BDC)3]8 and the microscopic mechanism was that the binding force between Zn4O(BDC)3 and NMP molecule was weaker than DMF.
基金the National Basic Research Program of China (No.2012CB214900)the National Natural Science Foundation of China (No.51274201)+1 种基金the Coal Joint Fund from National Natural Science Foundation of China and Shenhua Group Corporation Limited (No.U1361116)the Priority Academic Program Development of Jiangsu Province Higher Education Institutions
文摘The content and the caking index of the heavy,the dense medium and the loose medium components of coal,obtained by extraction and stripping with CS_2/N-methyl-2-pyrrolidinone mixed solvent(1:1 by volume),were studied and correlated with the caking property of raw coals.Images of the three group components after heat treatment were analyzed.The results show that both caking index(G) and maximum thickness of plastic layer(Y) of coals have a good linear relationship with the content of the medium component;the dense medium and the loose medium components are the two key factors to determine the caking property of raw coals-they are the source materials of fluidity and swelling of coal,respectively;the heavy component without the swelling and fluidity was cohered by the other components;two new indexes,which can extend current understanding of the caking properties,were introduced.
基金Supported by China Petroleum & Chemical Corporation(No.200049).
文摘Terephthalic acid(PTA) is practically one of the main materials of polyester. Its corresponding solid-liquid equilibrium data will provide essential support for industry design and further theoretical studies. In this work,solid-liquid equilibriums of terephthalic acid in four solvents, N,N-dimethylformamide, N,N-dimethylacetamide,dimethylsulphoxide and N-methyl-2-ketopyrrolidene, were determined in the temperature range from 293.15 K to 364.6 K by dynamic method. All these data were regressed by λh model, Wilson model and NRTL model, average absolute relative deviations of which are 1.25%, 15.02% and 7.22% respectively. It indicates that λh model is mostsuitable for description of the solid-liquid equilibrium containing PTA.
文摘Poly(p-phenylene terephthalamide)(PPTA)pulp was prepared by polycondensation of the p-phenylene diamine(PPDA)with terephthaloyl chloride(TPC)in the completely anhydrous solvent system of N-methyl pyrrolidone(NMP)having calcium chloride,in the presence of poly(vinyl pyrrolidone)(PVP)having a viscosity average molecular weight lower than 40 000.It was confirmed that the polycondensation could be accelerated,the inherent viscosity of the polymer could be increased,and the polymers could be fibrillated more easily by the addition of the PVP.FTIR and X-ray spectra proved that PVP had not combined into molecular chains of the resultant PPTA pulps.The morphology of the resultant pulps,the effect of viscosity average molecular weight,amount and adding mode of PVP on inherent viscosity,specific surface area,and mean length of the resultant pulps were discussed in detail.And the friction and wear properties of the compound reinforced by the resultant pulps were simply investigated.
文摘Improvement of coking properties of sub-bituminous coal (A) and bituminous coal (B) was done using blended organic solvents, namely, n-methyl-2-pyrrolidinone (NMP) and ethylenediamine (EDA). Various solvent blends were employed for the coal extraction under the total reflux condition. A low-cost ceramic membrane was fabricated using industrial waste iron ore slime of M/s TATA steel R&D, Jamshedpur (India) to separate out the dissolved coking fraction from the solvent-coal mixture. Membrane separations were carried out in a batch cell, and around 75 % recovered NMP was reused. The fractionated coal properties were determined using proximate and ultimate analyses. In the case of bituminous coal, the ash and sulfur contents were decreased by 99.3 % and 79.2 %, respectively, whereas, the carbon content was increased by 23.9 % in the separated coal fraction. Three different cleaning agents, namely deionized water, sodium dodecyl sulphate and NMP were used to regain the original membrane permeability for the reusing.
文摘Catalyst plays an important role in the dehydration of N-(hydroxylethyl)pyrrolidone (NHP) to prepare N-vinyl-pyrrolidone (NVP). At present, NVP yield is only about 30% on commercial ZrO2 catalyst. A coupled precipitation and solid dispersion technique was designed to prepare the nano-ZrO2 catalyst, in which rare earth metal oxides (REOx) was used as electronic promoter. The results indicated that the catalyst doped REOx (S-1.0) exhibits the optimum performance of NHP dehydration at moderate conditions. NHP conversion and NVP selectivity are respectively 97.0%, 82.3%. Of special interest is that the indexes of the catalyst (S-1.0-1.0) are up to 98.4% and 89.2% respectively. Furthermore, this catalyst bears the good stability. It means that nano-ZrO2 doped REOx catalyst might be a potential commercial catalyst for the NHP dehydration.
文摘Kinetics of copolymerization of acrylonitrile(AN) with N-vinylpyrrolidone(NVP) initiated by azodi-isobutyronitrile(AIBN) was investigated in H2O/dimethyl sulphoxide(DMSO) mixture between 50℃ and 70℃ under N2 atmosphere. The rate of copolymerization and particle size were measured respectively. The kinetic equation of copolymerization system is obtained as Rpat 60℃. The overall activation energy for copolymerization system was computed as 87.3kJ.mol-1. Effect of additives of hydroquinone and dioxane on copolymerization was discussed. The polymerization is retarded by hydroquinone and accelerated by dioxane, which confirms the free radical copolymerization of AN with NVP.
文摘With N-vinyl-2-pyrrolidone (NVP) and itaconic acid(IA), poly(N-vinyl-2-pyrrolidone/itaconic acid)[P(NVP/IA)] hydrogel was synthesized by free radical solution polymerization. The structure of this (P(NVP/IA)) was characterized by IR. Effects of concentration of itaconic acid, amount of cross-link agent, N,N′-methylene-bis-acrylamide, reaction temperature, and time on properties of swelling ratio(SR) of the hydrogel were investigated.The results show that the best swelling property of the hydrogel is obtained at 50 ℃ and 1.5 h. pH sensitivity increases as the concentration of itaconic acid in the hydrogel system increases. Swelling ratio of the hydrogel decreases as the amount of cross-link agent increases.
文摘Nano-silver/polyvinylpyrrolidone(PVP)composite materials were successfully synthesized bi-insitu from silver nitrate solution with N-vinyl pyrrolidone (NVP) monomer,containing neither initiator nor reductant, in ultraviolet irradiation conditions.The resultant Ag/PVP nanocomposites were characterized by infrared spectroscopy (FT-IR), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD).TEM show that nano silver particles are homogeneously dispersed in PVP polymer matrix, and the mean size of spherical silver particles is about 5 nm.The spectroscopy of XPS and FTIR showed that there is an interaction between nano silver not only with carbonyl oxygen but also with the nitrogen group within the NVP molecule through the p-π conjugation effect in the nano-silver/PVP composites system.
基金This work was supported by the National Natural Science Foundation of China and the funds of the Key Laboratory of Organic Syntheses of Jiansu Province
文摘The crystal structure of the title compound UO2(NO3)2[CH2(CH2)2CONC8H17] was determined by single-crystal X-ray diffraction. Crystal data: triclinic, space group P , a = 7.456(2), b = 8.371(2), c = 13.470(3) ? ?= 95.66(1), ?= 94.64(2), ?= 102.67(2), C24H46N4O10U, Mr = 788.68, V = 811.7(3) ?, Dc = 1.613 g/cm3, Z = 1, F(000) = 390, ?= 5.052 mm-1, the final R = 0.0256 and wR = 0.0568 for 2826 observed reflections (I > 2(I)). The central uranyl ions are coordinated by six oxygen atoms. Two of them are from the carbonyl groups of N-octyl-a-pyrrolidone molecules, and the other four from two nitrate groups.
基金supported by the Elements Strategy Initiative for Catalysts and Batteries (ESICB)a Grant-in-Aid for Scientific Research (26248003, 15H01042) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan
文摘The mass spectrometry of gold clusters stabilized by poly(N‐vinyl‐2‐pyrrolidone) (Au:PVP) re‐vealed the presence of Cl adsorbates derived from synthetic precursors, mainly on the Au34 and Au43 clusters. Changes in the amount of Cl adsorbates on the Au clusters did not affect the catalytic prop‐erties for the aerobic oxidation of benzyl alcohol, suggesting that the Cl atoms were only weakly bound to the Au clusters. In contrast, the replacement of Cl with Br on the Au34 and Au43 clusters significantly suppressed activity, without any influence on the electronic structure. This result indi‐cated that the Br atoms were strongly bound to the Au clusters and sterically blocked their active sites. The substantial reduction of the catalytic activity by the Br adsorbates suggested that the Au34 and Au43 clusters made a major contribution to the catalytic activity of the Au:PVP.
基金Project(51204211) supported by the National Natural Science Foundation of ChinaProject(2012M521543) supported by the China Postdoctoral Science Foundation
文摘High dispersed carbon black was applied for LiFePO4 cathodes as conductive agent.Nano-conductive carbon agent was pre-dispersed with poly acrylic acid(PAA) as dispersant in organic N-methyl-pyrrolidone(NMP) solvent system.The dispersion property of nano-conductive carbon agent was evaluated using particle size distribution measurements,scanning electron microscopy(SEM) and transmission electron microscope(TEM).LiFePO4 cathode with as-received nano-conductive carbon agent(SP) and LiFePO4 cathode with pre-dispersed nano-conductive carbon agent(SP-PAA) were examined by scanning electron microscopy(SEM),cyclic voltammetry(CV),electrochemical impendence spectroscopy(EIS) and charge/discharge cycling performance.Results show that the dispersion property of carbon black is improved by using PAA as the dispersant.The LiFePO4 cathodes with SP-PAA exhibit improved rate behaviors(4C,135.1 mAh/g) and cycle performance(95%,200 cycles) compared to LiFePO4 cathodes with SP(4C,103.9 mAh/g and 83%,200 cycles).Because pre-dispersed carbon black(SP-PAA) is dispersed homogeneously in the dried composite electrode to form a more uniform conductive network between the active material particles,electrochemical performances of the LiFePO4 cathodes are improved.
基金National Natural Science of Foundation of Chinagrant number:81070716
文摘In this study, the polyacrylate intraocularr lens is irradiated by argon ion which can produce free radicals. In order to obtain better hydrophilic and lower platelets adhesion, monomer vinyl pyrrolidone (NVP) is grafted onto the hydrophobic polyacrylate intraocular lens surface in a certain reaction conditions. Specific changes in intraocular lens are detected by static contact angle (CA), scanning electron microscope (SEM) and light transmittance. The results show that this surface modification can greatly improve its hydrophilic character and surface formation.
文摘Experimental data on density and viscosity at 303.15K and 323.15K are presented for the binary mixtures of p-xylene with cyclohexane, n-heptane, n-octane, sulfolane, N-methyl-2-pyrrolidone and acetic acid.From these data, the excess molar volume and deviations in viscosity have been calculated. The computed quantities have been fitted to the Redlich-Kister Equation to derive coefficients and estimate the standard error values. Results are discussed in terms of intermolecular interactions.
文摘Monophasic mullite gel with composition 3Al2O3·2SiO2 was prepared by the sol-gel method using aluminium nitrate nonahydrate, aluminium-tri-isopropoxide, and tetraethylorthosili-cate as reagents. Gels with different drying control chemical additives(DCCAs) and polyvinylpyrrolidone(PVP) as spinning assistant were dried at several temperatures. The influences of temperature, DCCAs and PVP in the drying process were investigated. N,N-dimethylformamide(DMF) was the optimum DCCA at 70℃ in the drying process. PVP decreased the solvent volatilization speed and prevented gel crack to a certain extent. FTIR results revealed that free water, ethanol, and isopropanol were completely removed by the drying procedure.