Hydrophilic polymer membranes containing carboxylic groups—I. Acrylic acid—methyl methacrylate—glycidyl methacrylate copolymers

Copolymers of acrylic acid, methyl methacrylate and glycidyl methacrylate have been synthesized and converted into cross-linked hydrophilic membranes by successive treatments with heat, alkali solution and acidic solution. The copolymerization was carried out in solution using tetrahydrofuran and p-dioxane as solvents. The polymer was obtained as a clear viscous solution at yields of approximately 95%. The polymerization was stopped before gelation took place. This gelation resulted from the reaction of epoxy and carboxylic groups of the polymeric chain. The polymerization time ranged from 3.5 to 7 hr depending on the content of the glycidyl methacrylate in the feed. The monomer mixture consisted of 25–45 mol% of acrylic acid, 40–70 mol% of methyl methacrylate and 2.5–15 mol% of glycīdyl methacrylate. With increasing content of acrylic acid, the membranes became soft and elastic; with decreasing content, they became brittle and hydrophobic. The swelling of the cured polymeric film increased with increase in the acrylic acid content of the monomer mixture and decreased with increasing glycidyl methacrylate content. Dialysis runs were conducted with sodium chloride, urea and a series of ethylene glycols with molecular weights up to 600. The permeability coefficients through the membranes for the ethylene glycols were similar to those through a commercial cellulose membrane (Cuprophane). The permeability proportional to $\text{(permeant molecular wt)}{}^{\mathrm{<mtext>?</mtext><mtext>1</mtext><mtext>2</mtext>}}$. The membranes showed very low permeabilities to sodium chloride compared with those of commercial nonionic membranes. This appears to be due to the ionic exclusion mechanisms expected for ion exchange membranes.     

深圳市1408例儿童发中钙,铁,镁含量调查与分析

用火焰原子吸收法检测了深圳市１４０８例１３岁以下儿童发中钙，铁，镁的元素含量，并探讨了元素含量与年龄，性别的关系，结果显示，性别差异有显著意义，钙，镁含量随年龄增长有相似变化。     

Perfluorinated anion-exchange polymer mercury film electrode for anodic stripping voltammetric determination of zinc(II): effect of model organic compounds

The determination of zinc ion (1-60 ng ml⁻¹) by anodic square-wave stripping voltammetry on an anion-exchange perfluorinated polymer Tosflex mercury film electrodes (TMFE) was evaluated. The detection limit was 0.1 ng ml⁻¹ Zn(II). The effect of various organic compounds (gelatin, albumin, starch, camphor, humic acid, Triton X-100, sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB)) is explored. The results indicate that due to the size-exclusion and ion-exchange properties of Tosflex film, the TMFE is considerably more resistant to organic interference than the bare mercury film electrode.     

双核银络合物[Ag_2(dppm)_2(Py)_2(μ-Cl)]ClO_4的合成与结构

二-(二苯基膦)甲烷(dppm)是一种易与金属形成多核络合物的有机膦配体。我们用dppm作为配体合成了一系列银的多核络合物,并对其结构进行了研究。本文报导了其中一个双核化合物[Ag_2(dppm)_2(Py)_2(μ-Cl)]ClO_4的合成及晶体结构、分子结构的测定。     

Ab Initio Study of Prednisolone, 6α-Fluoroprednisolone, 9α-Fluoroprednisolone,and 6α,9α-Difluoroprednisolone

A theoretical study of prednisolone, 6-fluoroprednisolone, 9-fluoroprednisolone, and 6,9-difluoroprednisolone has been performed at the ab initio HF/6-31G, MP2/6-31G, and B3LYP/6-31G levels. Structural information and the electronic features of prednisolone and its derivatives and the synergistic effect of 6,9-difluoroprednisolone was examined. Contrary to the AM1 and MNDO results, we found 9-fluoroprednisolone is more stable than the 6-fluoroprednisolone. The increased corticosteroid activity of the 6,9-difluoroprednisolone is most likely due to electronic effects, mainly related to the receptor binding.     

Isoochotensine,a New Spirobenzyusoquinoline Alkaloid from: Corydalis Ochotensis Turcz

Separation of the phenolic fraction of Corydalis ochotensis afforded a new spirobenzylisoquinoline alkaloid, isoochotensine ( 1 ) and three known alkaloids, ochotensine ( 3 ), cheilanthifoline ( 7 ), and lienkonine ( 9 ) as their acetyl derivatives together with a known nonphenolic alkaloid, ochotensimine ( 5 ). Their structures were elucidated by the spectral data.     

Cationic polymerization with boron halides. V. Synthesis of poly(isobutylene-b-styrene) and poly(styrene-b-isobutylene)

Block copolymers of isobutylene and styrene, PIB-b-PSt and PSt-b-PIB, have been prepared by a two-step synthesis involving (1) preparation of terminally chlorinated (telechelic) polyisobutylene or polystyrene “prepolymers” by using the H₂O/BCl₃ initiator system and (2) blocking from these telechelic prepolymers a second polymer segment by using an alkyaluminum, e.g., Et₂AlCl coinitiator. The telechelic polyisobutylene and polystyrene contain tertiary and benzylic chlorine termini, respectively. Block copolymer characterization included detailed selective solvent extraction procedures, coupled with GPC determinations, PMR, solubility, and intrinsic viscosity studies. The synthesis of PIB-b-PSt and PSt-b-PIB provides direct chemical evidence for the presence and position of active chlorine termini in BCl₃-coinitiated olefin polymerizations.     

Harnack Inequalities for Functional SDEs Driven by Subordinate Brownian Motions

Potential Analysis - Using coupling by change of measure and an approximation technique, Wang’s Harnack inequalities are established for a class of functional SDEs driven by subordinate...     

A theory of tensor products for module categories for a vertex operator algebra,I

This is the first part in a series of papers developing a tensor product theory for modules for a vertex operator algebra. The goal of this theory is to construct a vertex tensor category structure on the category of modules for a suitable vertex operator algebra. The notion of vertex tensor category is essentially a complex analogue of the notion of symmetric tensor category, and in fact a vertex tensor category produces a braided tensor category in a natural way. The theory applies in particular to many familiar rational vertex operator algebras, including those associated with WZNW models, minimal models and the moonshine module. In this paper (Part I), we introduce the notions ofP(z)- andQ(z)-tensor product, whereP(z) andQ(z) are two special elements of the moduli space of spheres with punctures and local coordinates, and we present the fundamental properties and constructions ofQ(z)-tensor products.