Synthesis and Mesogenic Properties of Liquid Crystals Containing Terminal Cyclohexylmethanol,Cyclopentylmethanol, Cyclobutylmethanol and Cyclopropylmethanol Moiety

Four series of compounds 11?50 containing terminal alicyclic rings such as cyclohexylmethyl, cyclopentylmethyl, cyclobutylmethyl, and cyclopropylmethyl rings were synthesized and their liquid crystal behavior studied. The ring size and the length of flexible alkoxy chain influence the phase formation in different ways. While the smaller ring and the shorter alkoxy chain tend to favor the formation of the N phase, the larger ring and the longer alkoxy chain tend to favor the formation of the SmC phase. All the compounds except 11 and 21 exhibit SmA phases. The widest temperature range of the N, SmA, and SmC phases are found in the compounds 41 , 46 , and 20 , respectively, which are 75 °C for 41 , 115 °C for 46 , and 100 °C for 20 .     

Decontamination of radioactive cesium from natural NaCl by amide-type open-chain crown ethers

An attempt has been made to develop a radiochemical methodology for the decontamination of a trace amount of radioactive cesium from a bulk amount of natural NaCl by liquid-liquid extraction (LLX). Open chain crown ethers, of amide type, namely, N,N,N",N"-tetraphenyl-3,6-dioxaoctanediamide (TDD), N,N,N",N"-tetraphenyl-3,6,9-trioxaundecanediamide and N,N"-dinaphthyl-N,N"-diphenyl-3,6-dioxaoctanediamide (DDD) have been chosen for this purpose. The separation factor between Cs and Na is the highest when 10^-4M TDD dissolved in nitrobenzene is used as extractant and 0.4M picric acid at pH 5.0 is used as aqueous phase. About 60% Cs is extracted in this condition in a single run.     

Synthesis of 2'-O-methoxyethylguanosine using a novel silicon-based protecting group

A short and efficient synthesis of 2'-O-methoxyethylguanosine (8) is described. Central to this strategy is the development of a novel silicon-based protecting group (MDPSCl(2), 2) used to protect the 3',5'-hydroxyl groups of the ribose. Silylation of guanosine with 2 proceeded with excellent regioselectivity and in 79% yield. Alkylation of the 2'-hydroxyl group of 6 proceeded with methoxyethyl bromide and NaHMDS and afforded compound 7 in 85% yield, without any noticeable cleavage of the silyl protecting group and without the need to protect the guanine base moiety. Finally, deprotection of 7 was achieved using TBAF and produced 8 in 97% yield.     

Tetra‐n‐butylammonium bis(2‐thioxo‐1,3‐dithiole‐4,5‐dithiolato‐κ2S4,S5)nickelate(III)

The crystal structure of the title compound, (C₁₆H₃₆N)[Ni(C₃S₅)₂], is isomorphous with that of the corresponding Pt complex but different from the structures reported for compounds of the same chemical composition, and so provides a new crystalline phase of this complex. The nickel complex anion has good planarity and lies on a crystallographic inversion centre. There is disorder in the two terminal C atoms of two of the butyl chains of the tetra‐n‐butyl­ammonium cation, the N atom of which is located on a twofold axis.     

Effect of nucleating agent on the structure and properties of polypropylene/poly(ethylene-octene) blends

The effect of the sorbital nucleating agent on properties of the ethylene-octene copolymer (POE) toughened polypropylene (PP) was studied. The results show that the addition of POE increases notched Izod and Charpy impact strength significantly but impair the tensile strength and flexural modulus. As a nucleating agent (1,3,2,4-di(p-methylbenzylidene) sorbitol, DM) was added, the toughness and stiffness of toughed PP increased simultaneously at the same content of POE. This result shows that the toughness and stiffness of toughed PP are in balance. Polarized light microscopy analysis shows that with the addition of POE and nucleating agent, only a low level of PP spherulites were observed.     

Calculation of Gurney parameters for aqueous tetraalkylammonium halides based on Friedman's cosphere-overlap model

Recalculations of the Gurney free-energy parameters A_ij based on the cosphereoverlap model of Friedman and co-workers have been made using more recent experimental data. Our procedure for calculation seems to be more systematic than those previously reported. The excess energy, entropy, and volume parameters (E_ij, TS_ij, and V_ij) were also recalculated for some aqueous tetraalkylammonium halides. In addition, the excess-heat-capacity parameters C_ij are also reported here for the first time. These data are discussed briefly in terms of the structural implications.     

离子交换树脂纯化酪蛋白磷酸肽研究

通过单因素实验和正交试验确定了使用D-201型大孔强碱性阴离子交换树脂纯化酪蛋白磷酸肽(CPPs)的操作条件为：洗脱温度40℃、洗脱酸(HCI)浓度0．2mol／L、洗脱速度2．3ml／min、进样浓度2％(w／v)，进一步应用HPSEC技术分析考察了离子交换树脂纯化后含磷洗脱峰分子量分布情况，并计算了产品氮磷比与纯化收率．     

Formation of SnO2 Nanoparticles on External Surface of NaY Zeolite

Tin dioxide nanoparticles of 5 nm in size were prepared on NaY zeolite external surface by impregnation of SnCl2 solution and subsequent calcination at 623 K. A SnO2-NaY based chemical sensor for detecting H2 was demonstrated.     

Interaction between sodium tanshinone IIA sulfonate and the adriamycin semiquinone free radical: A possible mechanism for antagonizing adriamycin-induced cardiotoxity

Adriamycin (ADR) is a powerful and widely used antitumor drug, but its dose dependent cardiotoxicity limits its application. This side effect is believed to be caused by the adriamycin semiquinone free radical (ASFR). The primary focus of this work is to test effects of sodium tanshinone IIA sulfonate (STS) on ASFR and adriamycin–induced lipid peroxidation. It was found that ADR, whether in the system of heart homogenate, heart mitochondria or heart submitochondria, with NADH as the substrate or in xanthine/xanthine oxidase under anaerobic conditions, all produced ASFR rapidly. STS was shown to effectively scavenge ASFR in all these systems and postpone the appearance of ASFR. The delayed time was proportional to the amount of STS. Under aerobic conditions, ASFR could be oxidized to generate oxygen free radicals. STS could not scavenge these oxygen free radicals, but it could effectively scavenge lipid free radicals generated from membrane lipid peroxidation of heart mitochondria. STS could significantly reduce mitochondrial swelling and lipid peroxidation induced by ADR. Animal experiments show that treatment of STS could inhibit endogenous lipid peroxidation caused by ADR. Here, a protective mechanism of STS is suggested that STS can rapidly and univalently oxidize ASFR, causing the cycle of adriamycin between its quinone form and semiquinone form and inhibiting the accumulation of ASFR. Under aerobic condition, STS can protect heart mitochondria by scavenging lipid free radicals generated from adriamycin-induced mitochondrial lipid peroxidation. This investigation shows that STS may be a physiological drug to antagonize the cardiotoxicity of ADR.     

利用DPN技术直接构建磁性纳米图形

在纳米尺度下构建有序的磁性模板和图形是当前的研究热点之一 [1,2 ] .这种模板在生物样品的分离[1] 、磁电子学研究和信息存储 [2 ] 等领域具有重要意义 .目前 ,光刻 [3] 、微触点印刷 [4 ] 和自组装 [5] 等多项技术已被用来构建各种纳米模板 .1 999年 ,美国西北大学 Mirkin小组 [6 ]发明的 Dip- pen纳米刻蚀技术 (简称 DPN技术 )更在可控组装方面显示出巨大优越性 .这项技术是在一定驱动力作用下 ,使吸附在原子力显微镜 ( AFM)针尖上的分子“墨水”逐渐转移到基底表面上 ,实现纳米模板的可控构建 .与传统技术相比 ,DPN技术可在纳米尺…