聚二甲基硅氧烷分子尺寸的温度依赖性

作者等用Elias沉淀点法求得聚二甲基硅氧烷-乙苯-邻苯二甲酸二乙酯体系在10—100℃间的一系列θ-溶剂组成。从聚二甲基硅氧烷一个级份(M_η=1.4·10~6)的这些θ-溶液特性粘数测定得到dln[η]θ/dlnT=0.45,按Flory-Fox特性粘数理论计算得dlnh~2_0/dlnF=0.30,即聚二甲基硅氧烷分子的无扰尺寸随温度升高而增大。由于Me_2SiO单元间的偶极-偶极相互作用使分子链的左右式构象的位能低于反式构象的位能。     

聚二甲基硅氧烷分子尺寸的温度依赖性——Ⅱ.溶剂效应

聚二甲基硅氧烷分子尺寸的温度依赖性,文献报导出入甚大.Ciferri测定了一个试样在二甲基硅油中30—150℃的特性粘数.Mark、Flory测定了两个级份(M_w=2.5×10~6,4.3×10~5)在二甲基硅油中30—105℃的特性粘数,从所得良溶剂内[η]值依据稀溶液理论外推;钱人元、余世诚、高玉书采用乙苯-邻苯二甲酸二乙酯混合溶剂体系,在     

聚二甲基硅氧烷在混合溶剂中的粘度和光散射

用Elias沉淀点法求取聚二甲基硅氧烷25℃在乙苯-邻苯二甲酸二乙酯体系,庚烷-二氧六环体系的θ-溶剂组成。测定了聚二甲基硅氧烷八个级份在甲苯溶液中光散射和两种θ-溶剂中特性粘数,得到 [η]_θ=7.62×10~(-2)(?)_ω~(0.50)乙苯-邻苯二甲酸二乙酯体系γ_ω=19.0％ [η]_θ=8.28×10~(-2)(?)_ω~(0.50)庚烷-二氧六环体系γ_ω=77.2％ 聚二甲基硅氧烷分子无扰尺寸存在溶剂介质依赖性。     

聚甲基丙烯酸己磺酸钠特性粘数与数均分子量关系

前文已报导了具有较好抗凝血性能的新型聚电解质,聚甲基丙烯酸己磺酸钠(PSSH-MA)的合成,用统计方法对盐存在时PSSHMA溶液的粘性研究及用小角激光光散射法测定的PSSHMA体系的特性粘数和重均分子量的关系。本文进一步用KNAUER膜渗透计测定了该体系的特性粘数与数均分子量的关系^[6],并进一步探讨聚电解质水溶液渗透压测定中的一些问题。     

高聚物各种平均相对分子质量的绝对测定——GPC和特性粘数法

从GPC数据和特性粘数能较准确迅速求出高聚物的数均、粘均、重均、Z均相对分子质量及相对分子质量与特性粘敷关联参数。该方法经聚甲基丙烯酸甲酯验证后,用其表征了聚碳酸亚乙酯(PEC)和聚碳酸亚丙酯(PPC)。     

聚壬酰胺在苯酚-乙酸混合溶剂中的特性粘数-分子量关系

以苯酚为溶剂,甲醇为沉淀剂将三个聚壬酰胺试样(??各为20400,12900和7100)分级沉淀.每一试样至少经过二次分级,共得到二十级份.取其中七个级份测定其数均分子量及特性粘数.粘度测定在25℃,溶剂用苯酚-乙酸(2∶1重量比).在分子量4300-20000内,得到下列特性粘数-分子量关系: [η]=7.52×10~(-3)M~(0.96)ml/g M=200[η]-360 苯酚-乙酸(2∶1重量比)混合溶剂容易纯化且不引起聚壬酰胺的降解,能溶解尼龙-6,66,7,9和11,可作聚酰胺粘度测定的普适溶剂.     

高聚物各种平均相对分子质量的绝对测定——GPC和特性粘数法

从ＧＰＣ数据和特性粘数能较准确迅速求出高聚物的数均、粘均、重均、Ｚ查对分子后进琢相对分子质量与特性粘数关联参数。该方法经聚甲基丙烯酸甲酯验证后，用其表征了聚碳酸亚乙酯（ＰＥＣ）和聚碳酸亚丙酯（ＰＰＣ）。     

聚甲基丙烯酸三烷基锡酯的溶解性能和溶度参数的订定

本文研究了聚甲基丙烯酸三丁基锡酯(PTBTM)和聚甲基丙烯酸三甲基锡酯(PTMTM)在约六十种溶剂中的溶解性能。测定了它们在不同性质溶剂中的特性粘数,订定了PTBTM和PTMTM的溶度参数。并就有机锡聚合物中锡原子上的取代基对其溶解性能的影响进行了讨论。     

一点法测定特性粘数

高聚物的分子量可由溶液的特性粘数求得。特性粘数通常要从几个浓度的溶液粘度作图外推得到,这是比较麻烦费时的。为了提高测定特性粘数效率和尽快得到可靠的数据,以便指导生产实践,文献中早有从一个浓度溶液的测定数据计算特性粘数。近年来,许多人仍重视该问题的研究,并设计成了一种快速测定一个浓度溶液的粘度计和计算     

从GPC和特性粘数计算高聚物各种平均相对分子质量的新方法

聚合物相对分子质量表征问题可以从ＧＰＣ数据和特性粘数较可靠地迅速解决，同时求出其烽均、粘均、重均，动力学平均相对分子质量及相对分子质量－特性粘数关联参数。为些须对以往方法作较大的改进，其关键是用迭代法进行特性粘数与相对分子质量的关联。方法经用聚甲基丙烯酸甲酯验证后用于聚碳酸亚乙酯（ＰＥＣ）和聚碳酸亚丙酯（ＰＰＣ）分别得到关系式。     

中国硫回收技术进展(英文)

综述了国内硫回收技术的现状,并对今后１０－１５年内硫回收技术的发展进行了展望。     

INCREASED UV EXPOSURE IN FINLAND IN 1993

Abstract—
Exceptionally low total ozone, up to 40% below the normal level, was measured over Northern Europe during winter and spring in 1992 and 1993. In 1993 the depletion persisted up to the end of May, resulting in a significant increase of biologically effective UV radiation. The increases were significantly smaller in 1992 and 1994 than in 1993. The UV exposure of the Finnish population was evaluated through measurements and theoretical calculations. The increase in measured erythemal (International Lighting Commission) UV falling onto horizontal surfaces on clear days was determined relative to model calculations for an average ozone amount. The increase was on average 10% from April to May 1993, and the maximal measured increase was 34%. Theoretical calculations for both erythemal and carcinogenic (Skin Cancer Utrecht-Philadelphia) UV indicated that in 1993 the theoretical annual increase to a vertical (cylinder) surface ranged from 8 to 13% in Finland. The reflection of UV from snow considerably increases facial UV doses in Northern Finland.     

COLLOID CHEMISTRY IN PETROLEUM INDUSTRY IN CHINA

Wool-wax alcohols are remarkably effective in stabilization of water-in-oil emulsions. The structural changes in the continuous phase have been analysed by X-ray diffraction technique between the emulsification temperature, when the alcohol phase is liquid, down to room temperature. Evidence is given for the formation of sterol multilayer structure at the oil/water interface. The bilayer thickness of the sterols is 34,3 Å, and at about 37 °C there is a transition into a phase with X-ray data in close agreement with these of anhydrous cholesterol. The aliphatic alcohol molecules, which thus separate from the sterol molecules, start to form an ordered structure at about 50 °C. First a lamellar liquid-crystalline phase is formed with a bilayer thickness of 41,1 Å. Ano α-crystal phase, with hexagonal chain packing and vertical molecules is formed at further cooling to about 40 °C. The relation between emulsion stability and ordered interfacial structure is discussed.     

ICP-AES 法测定我国三个不同地域生长的板栗中20种元素

应用ICP—AES测定了我国三个不同地域生长的板栗中20种无机元素的含量并作了成分的比较研究，对试样的溶解条件及仪器的工作参数也进行了研究和优化。各元素分析结果的RSD值在0．11％～6．9％之间，回收率在95．1％～108．0％之间。     

RHODOPSIN-PHOSPHOLIPID INTERACTION IN DETERGENT AND IN THE DISK

Abstract— Solubilization of cattle disk membrane in deoxycholate shifted the fluorescence emission maximum from 324 to 331 nm without changing the intensity. Tryptophyl residues are probably located at the hydrophobic interface between rhodopsin and phospholipid. Depletion of deoxycholate concentration from the solubilized disk by Sephacryl 200 column chromatography produced rhodopsin-phospholipid complexes with different characteristics that are the intermediate stages of membrane formation from homogeneous molecular solution. Association of rhodopsin takes place in a two-dimensional way even in the appreciably low content of phospholipid.
Sedimentation velocity studies showed that reassociation of lipid and rhodopsin occurs in 0.2% deoxycholate as well as in 0.05% sodium dodecylsulfate.
By using Sephacryl column we can now prepare, within 60 min, the rhodopsin-lipid complex that can form large vesicles in response to the addition of MgCl₂ without dialysis. This type of lipoprotein complex will be useful to the study of the mechanism of the two dimensional membrane formation.     

TRANSPORT OF LIGHT IN TISSUE IN PHOTODYNAMIC THERAPY

Abstract The dose rate in photodynamic therapy is proportional to the energy fluence rate and the concentration of the photosensitizer. Calculations of the energy fluence rate have been performed in slab, cylindrical and spherical geometries with the discrete ordinates transport method and diffusion theory. The attentuation of the energy fluence rate is least in slab geometry and greatest in spherical geometry. Violet (405 nm) light is attenuated much more rapidly than red (630 nm) light. Small tissue dimensions or narrow beam irradiation further decrease the energy fluence rate with radius and depth. Anisotropic scattering increases the energy fluence rate at large depths, but decreases it near the source. Measurements of the absolute energy fluence rate vs depth in a mouse tumor model exhibit an order of magnitude attenuation through the skin and a 3 mm thick tumor. Calculations of the energy fluence rate of the DHE fluorescence have been carried out to guide measurement of the concentration. Violet light excitation is much more efficient than red light excitation.