19F NMR study of relative polarities and reactivities of N-H,N-Hg,and N-Au bonds in 2-(4-fluorophenyl)benzimidazole and its PhHg and Ph3PAu derivatives in intermolecular exchange

It has been shown by the¹⁹F NMR method that the relative polarities of nitrogenelement bonds in 2-(4-fluorophenyl)benzimidazole and its PhHg and PPh₃Au derivatives increase in the order N-H19F NMR. It has been found that these reactions occur by a bimolecular associative mechanism and that the N-H bond is substantially less reactive than the N-Hg and N-Au bonds, which have identical reactivities within the limits of sensitivity of the method used.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1574–1580, August, 1995.This work was carried out with financial support from the Russian Foundation for Basic Research (Project No. 93-03-5528).     

NMR Study of the propagation center in the cationic polymerization of N-benzoyl-8-octanelactam. II. Investigation of the propagation center

The nature of the propagation center in the cationic polymerization of N-benzoyl-8-octanelactam initiated by octanoylium hexachlcroantimonate, SbCl₅, and Ph₃CAsF₆ in perdeuterated tetrachloroethane or its mixture with o-dichlorobenzene was studied using ¹H, ¹³C, ¹⁹F, ³¹P, ⁷⁵As, and ¹²¹Sb nuclear magnetic resonance (NMR) of model oligomers and the products of their end-capping with triphenylphosphine. In all cases, the nature of the propagation center has been found to be of an acylium ion pair with an SbCl₆^? or AsF₆^? counterion coordinated with the nearest benzoylamide group and cosolvated by the solvent. © 1994 John Wiley & Sons, Inc.     

M-M型纳米颗粒膜的巨磁电阻效应

探讨了M-M型纳米颗粒膜巨磁电阻效应的物理机制，指出了影响颗粒膜巨磁电阻效应的因素，推导出M-M型纳米颗粒膜巨磁电阻效应的计算公式。     

对城市供水行业改革的思考

分析了目前各地供水行业改革中遇到的问题,提出了加强政府对供水行业的监管力度,慎重选择投资主体和特许经营者,理顺供水价格调整机制等城市供水行业改革的措施。     

Collective mechanism for nuclear stopping and transverse flow in heavy-ion collisions

The role of filamentation instability of quark-gluon plasma, in explaining collective phenomena in relativistic heavy-ion collisions, has been analyzed. Using equations of SU(2) two fluid color hydrodynamics it is shown that this instability can significantly enhance nuclear stopping and might contribute to collective sideward flows.     

以中日韩自由贸易区为核心和先导的东北亚合作模式

2003年10月中日韩三国领导人在印尼巴厘岛《中日韩推进三方合作联合宣言》的签署之后，东北亚合作的问题日益成为人们关注的焦点，加强东北亚各国的合作不仅有利于促进亚太区域内各国经济的发展，促成亚太地区经济进一步崛起，还会化解东北亚各国之间的矛盾和冲突．东北亚的合作应当加强信任、走制度化的合作道路，创设以中日韩自由贸易区为核心和先导的东北亚合作模式．以次区域合作先行的模式来带动东北亚经济一体化的发展。     

Kinetics and mechanism of polymerization of methyl methacrylate initiated by stibonium ylide

Homopolymerization of methyl methacrylate (MMA) was carried out in the presence of triphenylstibonium 1,2,3,4-tetraphenyl-cyclopentadienylide as an initiator in dioxane at 65°C±0·l°C. The system follows non-ideal radical kinetics (R _p ∝ [M]^1·4 [I]^0·44 @#@) due to primary radical termination as well as degradative chain-transfer reaction. The overall activation energy and average value ofk ₂ ^p /k _t were 64 kJmol⁻¹ and 0.173 × 10⁻³ 1 mol⁻¹ s⁻¹ respectively     

Succinic acid adsorption from fermentation broth and regeneration

More than 25 sorbents were tested for uptake of succinic acid from aqueous solutions. The best resins were then tested for successive loading and regeneration using hotwater. The key desired properties for an ideal sorbent are high capacity, complete stable regenerability, and specificity for the product. The best resins have a stable capacity of about 0.06 g of succinic acid/g of resin at moderate concentrations (1–5 g/L) of succinic acid. Several sorbents were tested more exhaustively for uptake of succinic acid and for successive loading and regeneration using hot water. One resin, XUS 40285, has a good stable isotherm capacity, prefers succinate over glucose, and has good capacities at both acidic and neutral pH. Succinic acid was removed from simulated media containing salts, succinic acid, acetic acid, and sugar using a packed column of sorbent resin, XUS 40285. The fermentation byproduct, acetate, was completely separated from succinate. A simple hot water regeneration successfully concentrated succinate from 10 g/L (inlet) to 40–110 g/L in the effluent. If successful, this would lower separation costs by reducing the need for chemicals for the initial purification step. Despie promising initial results of good capacity (0.06 g of succinic/g of sorbent), 70% recovery using hot water, and a recovered concentration of >100 g/L, this regeneration was not stable over 10 cycles in the column. Alternative regeneration schemes using acid and base were examined. Two (XUS 40285 and XFS-40422) showed both good stable capacities for succinic acid over 10 cycles and >95% recovery in a batch operation using a modified extraction procedure combining acid and hot water washes. These resins showed comparable results with actual broth.     

Enthalpies of sorption of linear hydrocarbons (C2–C8) and chloroderivatives of methane and ethylene on the surface of hydrotalcite

Differential molar adsorption enthalpies (DMAE) were determined by gas chromatographic measurements of specific retention volume of vapors on the surface of two forms of Mg–Al hydrotalcite. A linear dependence of the DMAE on the number of the carbon atoms in hydrocarbons was observed for both form of hydrotalcite. The dependence of the differential molar adsorption enthalpies on the number of chlorine atoms in organic molecules is discussed. A linear dependence of DMAE on the molecular weight of chloroderivatives of methane and ethylene on the basic form in an order monochloromethane < dichloromethane < trichloromethane or vinylidene chloride < 1,1-dichloroethylene < trichloroethylene was found.