The speculation that a flat molecule without a side-chain might not readily undergo the hydrophobicity-driven process of aggregation has been shown to be a plausible proposition by the fact that pyrene molecules do no...The speculation that a flat molecule without a side-chain might not readily undergo the hydrophobicity-driven process of aggregation has been shown to be a plausible proposition by the fact that pyrene molecules do not form excimers even in a supersaturated solution with relatively high solvent aggregating power(SAgP).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
The thermodynamic ionization constant K° of p-nitrophenol in {10 mass% ethanol-water} mixed solvent is derived from measurements of its absorption spectrum and pH by the two methods: Debye--Huckel extrapolation a...The thermodynamic ionization constant K° of p-nitrophenol in {10 mass% ethanol-water} mixed solvent is derived from measurements of its absorption spectrum and pH by the two methods: Debye--Huckel extrapolation and polynomial approximation proposed by us in suitable buffer solution at constant ionic strength from 0.1 to 2.0 mol.kg^(-1) at 298.2 ± 0.2 K. The results from both methods are pK° =7.406 and 7.415, respectively. The effect of medium on the ultraviolet spectra of p-nitrophenol has been discussed.展开更多
Central inhibition, discovered by Sechenov in 1862, suggests that electrically stimulating the forebrain or medulla oblongata in frog generally suppresses reflexes. However, the underlying molecular mechanisms are sti...Central inhibition, discovered by Sechenov in 1862, suggests that electrically stimulating the forebrain or medulla oblongata in frog generally suppresses reflexes. However, the underlying molecular mechanisms are still unclear. Using ethanol (EtOH), noradrenalin (NA), and other neurotransmitters in thalamic preparations, Sechenov inhibition was stimulated in Bufo toads in this study. The result showed that, similar to Sechenov inhibition, the acute application of EtOH or NA excited the thalamus and prolonged the latency of withdrawal reflex. Our study evidences the involvement of α-adrenoceptors in such central inhibition, and explains the role of acute EtOH application in the in- duction of reflex inhibition.展开更多
基金This work was supported by the National Natural Science Foundation of China
文摘The speculation that a flat molecule without a side-chain might not readily undergo the hydrophobicity-driven process of aggregation has been shown to be a plausible proposition by the fact that pyrene molecules do not form excimers even in a supersaturated solution with relatively high solvent aggregating power(SAgP).
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.
基金Project supported by The National Natural Science Foundation of China.
文摘The thermodynamic ionization constant K° of p-nitrophenol in {10 mass% ethanol-water} mixed solvent is derived from measurements of its absorption spectrum and pH by the two methods: Debye--Huckel extrapolation and polynomial approximation proposed by us in suitable buffer solution at constant ionic strength from 0.1 to 2.0 mol.kg^(-1) at 298.2 ± 0.2 K. The results from both methods are pK° =7.406 and 7.415, respectively. The effect of medium on the ultraviolet spectra of p-nitrophenol has been discussed.
基金the Major State Basic Research Development Program of China (973 Program) (Grant No. 2005CB522503)
文摘Central inhibition, discovered by Sechenov in 1862, suggests that electrically stimulating the forebrain or medulla oblongata in frog generally suppresses reflexes. However, the underlying molecular mechanisms are still unclear. Using ethanol (EtOH), noradrenalin (NA), and other neurotransmitters in thalamic preparations, Sechenov inhibition was stimulated in Bufo toads in this study. The result showed that, similar to Sechenov inhibition, the acute application of EtOH or NA excited the thalamus and prolonged the latency of withdrawal reflex. Our study evidences the involvement of α-adrenoceptors in such central inhibition, and explains the role of acute EtOH application in the in- duction of reflex inhibition.
