Surface-initiated atom transfer radical polymerization of methyl methacrylate on magnetite nanoparticles

The synthesis of magnetite nanoparticles coated with a well-defined graft polymer is reported. The magnetite nanoparticles with an initiator group for copper-mediated atom transfer radical polymerization (ATRP), 2-(4-chlorosulfonylphenyl) ethyltrichlorosilane (CTCS) chemically bound on their surfaces were prepared by the self-assembled monolayer-deposition method. The surface-initiated ATRP of methyl methacrylate (MMA) was carried out with the CTCS-coated magnetite nanoparticles in the presence of free (sacrificing) initiator, p-toluenesulfonyl chloride. Polymerization proceeded in a living fashion, exhibiting first-order kinetics of monomer consumption and a proportional relationship between molecular weight of the graft polymer and monomer conversion, thus providing well-defined, low-polydispersity graft polymers with an approximate graft density of 0.7 chains/nm². The molecular weight and polydispersity of the graft polymer were nearly equal to those of the free polymer produced in the solution, meaning that the free polymer is a good measure of the characteristics of the graft polymer. The graft polymer possessed exceptionally high stability and remarkably improved dispersibility of the magnetite nanoparticles in organic solvent.     

传统大豆发酵食品的生理功能

本文综述了我国传统大豆发酵食品的各种功能性成分，总结了其生物调节功能，并针对我国传统大豆发酵食品的研究开发提出了一些建议。     

紫外分光光度法对微酸性电生功能水中有效氯成分的检测

作为测量有效氟的经典方法,碘量滴定法和DPD法(N,N-二乙基-1,4-笨二胺滴定法)各有其局限性,因此亟需一种简便、快捷的电生功能水分析、测定方法.本实验研究讨论了紫外分光光度法测量不同电解质的电生功能水中有效氟成分-HClO和ClO-的应用;并利用紫外扫描光谱对电生功能水贮存中的失效因素进行分析.实验证明紫外分光光...     

常德发酵米粉中的微生物分离纯化与鉴定

本文对常德发酵米粉中的微生物进行了分离纯化,并用试剂盒对其进行了鉴定.鉴定结果为胚芽乳杆菌（Lactobacillus plantaum）等十二株乳酸杆菌,鸟链球菌（Enterococcus avium）等五株乳酸链球菌,酿酒酵母（Saccharomyces cervisiae）等九株酵母菌.     

Optically detected cyclotron resonance in semiconductors

In high quality semiconductor crystals, occurrence of cyclotron resonance is beautifully reflected on luminescence spectra. This feature is demonstrated in typical elemental semiconductor Ge, both doped and undoped. One obtains new information of kinetics in free carriers, free excitons, bound excitons and electron-hole drops.     

Schiff's bases of polyallylamine

Summary Schiffs bases of polyallylamine were synthesized by the reaction with four aldehydes. Salicylaldehyde (S)- and 2-pyridinecarboxaldehyde (P)-Schiff's base could be used as reverse osmosis membranes when crosslinked with divinyl sulfone, diacetyl or ethylene glycol diglycidyl ether. S-base membrane had a high mechanical strength but poor water permeability (K₁), while P-base membrane showed a high rejection, particularly against CoCl₂, and a high K₁ because of chlate formation, but poor strength. The membranes of P-base and a hybrid PS-base exhibited a possibility of separating alkali metal salts and transition metal salts from each other.     

Properties of poly(4-vinylpyridine-co-methyl vinyl ketone) membranes for reverse osmosis

The copolymer prepared from 4-vinylpyridine and methyl vinyl ketone could form a dense and tough membrane which is stronger than cellulose acetate when crosslinked with malonyl dihydrazide (MD) or 2-phenyl-4,6-dihydrazino-s-triazine (PDT), showing a fair performance in reverse osmosis for NaCl and CoCl₂ feed. The relationship between the content of MD or PDT and the membrane performance was investigated. An increase in MD or PDT led to an increase in membrane thickness and water content as well as the performance. A maximum rejection was obtained at ca. 30 mol % MD and ca. 13 mol % PDT based on MVK, and a maximum membrane strength at 20–30 mol % crosslinking agent. A membrane of a lower NaCl rejection tended to be permselective due to the complexation of the CoCl₂ with membrane. About 1:1 copolymer gave membranes of a higher rejection, which may be related to monomer arrangement in the copolymer chain. There methods for the flux improvement were presented and discussed: preparation of a copolymer blend membrane containing a hydrophilic monomer, crosslinking quaternization of membranes with diiodobutane, and oximation of the membrane material in order to introduce hydrophilic groups.     

Rates of gas absorption with interfacial turbulence caused by micro-stirrers

Rates of absorption of CO₂ into water, a 0.2 mol/L NaOH solution and a 40 wt% glycerol solution with and without the interfacial turbulence caused by micro-stirrers, made of a magnetic material, were measured with use of a stirred vessel with known gas-liquid interfacial area. The effect of the interfacial turbulence on the rate of gas absorption was remarkable in the lower range of the bulk turbulence. The enhancement factors due to the interfacial turbulence were calculated with use of the age distribution function of the Danckwerts type and they agreed well with the experimental results.     

Gas absorption with consecutive chemical reaction: Absorption of carbon dioxide into aqueous amine solutions

Experiments were carried out over a wide range of contact time for the absorption of carbon dioxide into aqueous amine solutions. It was suggested from the experimental results with a laminar liquid-jet, a wetted wall column and a quiescent liquid absorber that the present absorption processes should be analyzed by a gas absorption with the consecutive reaction of the form of A + 2B →k_I R and A + R →k_II Products. The values of rate constants for the second-order first reaction step (k₁) for the diethanolamine and triethanolamine were estimated as 1340 and 16.8 1/mol-sec, respectively. The value of rate constant for the second reaction step was found to be constant irrespective of the liquid reactant.     

Properties of reverse osmosis membranes prepared from poly(4-vinyl pyridine)-acrylonitrile copolymer and the partially quaternized copolymer

Reverse osmosis membranes were prepared from 4-vinyl pyridine(4VP)-acrylonitrile (AN) copolymers and those partially quaternized. Their salt rejection (S) and hydraulic water permeability (K₁) were investigated with regard, to co-polymer composition, the membrane profile by SEM observation, cross-linking quaternization with diiodobutane (DIB) and the method of membrane preparation. S decreased with increasing AN content, but K₁ was closely dependent on water content which had a minimum at about 65% 4VP. The increase in K₁ and water content in a high AN range was caused by the change in the membrane structure from dense to porous one.Quaternization with DIB to a small extent notably improved K₁, up to ten times without significant change in S, and most effectively improved both of the membrane structure and the performance of AN rich copolymer membranes which were the highest in tensile strength among the copolymers. It was found by IR and elemental analysis that DIB charged was nearly completely reacted. The DIB modified membranes were anion exchangeable and more than two-thirds of iodide were exchanged for chloride. The modification reduced the membrane strength, to the least extent in the AN rich copolymers, with increasing DIB due to an increase in water content. The quaternized membranes prepared by surface-treating with DIB gave an essentially similar performance and had a composite structure which held unreacted layer.Monofunctional quaternizing agents merely brought about a poor membrane performance.Water transport through the membranes followed solution-diffusion mechanism for the membranes of volume fraction of water smaller than 0.41. The membranes modified with DIB to a small degree were regarded as tight ionic membranes and able to be treated as a nonionic ones, although they behaved ionically showing a decrease in S with the increasing feed concentration.