Thermomechanical heat of deformation studies on cis-polybutadiene

Thermomechanical heat of torsional deformation measurements have been made on crosslinked cis-polybutadiene by means of a Calvet microcalorimeter operated at 30°C. When corrected for volume changes utilizing the Gaussian statistical theory of elasticity, the data gave a value for the relative energy contribution to the torsional couple, $\text{M}{}_{\mathrm{e}}\text{M}$, of 0.14 ± 0.02. Measurements were also made on a sample subjected to simple tensile deformations. The relative energy contribution to the tensile force ($\text{f}{}_{\mathrm{e}}\text{f}$) was found to agree within experimental error with the value obtained for $\text{M}{}_{\mathrm{e}}\text{M}$, and the two results gave an average value for din $\text{〈r}{}^2{}_0\text{〉}\text{d}\text{T}$ of 4.1 × 10^?4 K^?1.     

1-(5-乙基-1,3,4-噻二唑基)-3-苯基硫脲的合成及生物活性

研究了 1 - ( 5 -乙基 - 1 ,3,4-噻二唑基 ) - 3-苯基硫脲的合成及抗菌活性。以 5 -乙基 - 2 -氨基 - 1 ,3,4-噻二唑和异硫氰酸苯酯为原料 ,在十六烷基三甲基溴化铵催化下 ,合成 1 - ( 5 -乙基 - 1 ,3,4-噻二唑基 ) - 3-苯基硫脲 ,找到了较好的合成工艺条件 ,结果表明 :5 -乙基 - 2 -氨基 - 1 ,3,4-噻二唑和异硫氰酸苯酯的摩尔比为 1∶ 1 .8,乙腈为溶剂 ,水浴加热回流 4.0 h,十六烷基三甲基溴化铵为 2 g,1 - ( 5 -乙基 - 1 ,3,4-噻二唑基 ) - 3-苯基硫脲的产率为 5 9.76%。同时发现 1 - ( 5 -乙基 - 1 ,3,4-噻二唑基 ) - 3-苯基硫脲有较强的抗菌活性     

A comparison of vapour pressure measurements of quinizarin and leuco-quinizarin via transpiration and thermogravimetry

The vapour pressure of solids can be obtained using a number of methods, including the Knudsen effusion method, the Knudsen torque-effusion method and a transpiration method. Each method has benefits and disadvantages. Reported is a comparison of vapour pressure data for two compounds, quinizarin and leuco -quinizarin, using a transpiration method and a recently developed method based on thermogravimetry. Thermogravimetry provided vapour pressure–temperature dependence data for each compound with expediency and in agreement with the transpiration method.     

5-烷基-2-氨基-1,3,4-噻二唑的合成及应用

用硫代氨基脲与甲酸、乙酸、丙酸、丁酸、异丁酸、异戊酸等在盐酸、磷酸、多聚磷酸、硫酸催化下 ,分别合成了 2 -氨基 -1 ,3 ,4-噻二唑 (a)、5 -甲基 -2 -氨基 -1 ,3 ,4-噻二唑 (b)、5 -乙基 -2 -氨基 -1 ,3 ,4-噻二唑 (c)、5 -丙基 -2 -氨基 -1 ,3 ,4-噻二唑 (d)、5 -异丙基 -2 -氨基 -1 ,3 ,4-噻二唑 (e)、5 -异丁基 -2 -氨基 -1 ,3 ,4-噻二唑 (f)。并对工艺条件进行了试验 ,结果表明 :最佳工艺条件为硫代氨基脲与酸的摩尔比为 1∶ 1 .4,合成 2 -氨基 -1 ,3 ,4-噻二唑为多聚磷酸催化 ,合成其它的为浓盐酸催化 ,回流 3 h,产率分别为 96.78%、74.3 4%、73 .67%、71 .68%、68.44%、67.5 4%。同时以 a～f为原料合成了具有抗菌作用的 5 -烷基 -1 ,3 ,4-噻二唑硫脲乙酸和 5 -烷基 -2 -苯基 -硫脲 -1 ,3 ,4-噻二唑的衍生物     

空间低温氧化物熔体晶体生长的数字模拟研究

地面上 ,由于受浮力对流、分层和沉淀等因素的影响 ,难以阐明晶体生产和凝固现象的本质 ,从而无法获得组份均匀、结构完整和性能优良的材料 ,因此自七十年代以来 ,已进行了大量的空间晶体生长实验 ,但由于对空间环境在晶体生长过程中的流体效应参数缺乏了解 ,实验结果往往与设想的不一致。数字模拟方法可以模拟实际晶体生产过程 ,了解晶体生长参数的变化对晶体生长的影响 ,本文利用数字模拟的方法 ,对本实验室建立的空间三维实时观察装置中 ,低温生产NaNO3熔体晶体中的流体效应及温场进行了数字模拟研究 ,结果表明 ,在地面生长 ,熔体内部存在复杂的双涡流动模式 ,重力对熔体中的温场和速度场的分布产生强烈的作用 ,而在空间 ,当微重力水平达到一定程度时 ,可以使熔体中的流动模式简单化 ,从而降低流动效应对传热、传质造成的不稳定性和不均匀性 ,有利于提高晶体生长的质量。同时通过对流场中的温度分布分析表明 ,降低重力可以明显改变晶体生长固液界面附近的温度梯度 ,并使温场 ,速度场分布朝着稳态生长的方向发展     

微通道内气-液传质研究

以CO₂-H₂O为模型体系，实验考察了当量直径为667 μm的单通道和16个并行通道内的气-液传质行为.实验发现，液体表观速度增加，单通道内液侧体积传质系数明显提高;同一液体表观速度下，液侧体积传质系数随气体表观速度增加而增加;在实验数据基础上关联了液侧体积传质系数与气-液两相流参数间的关系.微通道内的液侧体积传质系数较常规尺度气-液接触设备至少高1～2个数量级.并讨论了并行微通道内气-液两相流分配特性对整体传质性能的影响，表明合理设计气、液流动分布结构，可保证微通道内优异的传质特性.     

Lipids of seven cereal grains

Grain samples of representative varieties of barley, corn, oats, rye, sorghum, triticale, and wheat grown commercially in the north central US were analyzed. Chemical constituents of the varieties studied are presented to provide an overview of their characteristics. Lipids of the milled grain samples were solvent extracted, classified by silicic acid column chromatography, and separated by thin layer chromatography. Fatty acid composition of the total lipid was determined by gas liquid chromatography and the fatty acid content was determined by saponification and extraction. Total lipid content of the grains ranged from 2.3% for ‘Polk’ wheat to 6.6% for ‘Chief’ oats. Lipid composition varied considerably. The row crops, corn and sorghum, have a high neutral lipid and low glycolipid content. The small grain varieties have a more balanced distribution among neutral lipids, glycolipids, and phospholipids. Fatty acid composition of the total lipid was similar for all grains. Minor qualitative differences were noted among the lipid classes of the 7 cereals.     

Evaluation of thermodynamic theories to predict interfacial tension between polystyrene and polypropylene melts

The commonly used thermodynamic theories (mean field theory and the square gradient theory) to predict interfacial tension between polymers have been modified. The results of these theoretical developments have not yet been fully tested and compared to experimental data. In this paper, experimental data for the effects of temperature, molecular weight, and molecular weight dispersity on interfacial tension for polypropylene/polystyrene polymer pairs are compared with the predictions of the new versions of the above theories. To evaluate these theories, it is necessary to know the Flory-Huggins interaction parameter for the polymer pairs studied. The relation correlating the Flory-Huggins interaction parameter to the Hildebrand solubility parameter was not suitable for evaluating the theoretical predictions of interfacial tension. Instead, the Flory Huggins interaction parameter was expressed as the sum of an enthalpic contribution, χ_H, and entropic contribution, χ_s. In the absence of reliable experimental values, a method was developed to evaluate the two contributions, based on interfacial tension data. The procedure provided an interaction parameter that is allowed to depend on molecular weight. When this approach was used, the predictions of only the new version of the square gradient theory were in good agreement with the experimental data for the influence of temperature and molecular weight on interfacial tension. However, the theory predicted the effect of polydispersity on interfacial tension only at high temperatures.     

基于Android平台简易即时通讯的研究与设计

论文简单介绍Android平台的特性,主要阐述了基于Android平台简易即时通讯(IM)的作用和功能以及实现方法。     

Ultramicroscopy of association colloids formed from block copolymers

Ultramicroscopy studies have been made of micelle formation by two poly(styrene)-poly(isoprene) block copolymers in organic solvents (N,N-dimethylacetamide and n-decane respectively) and a poly(l-glutamic acid)-poly(l-leucine) block copolymer in an aqueous solution of 0.2M NaCl at pH = 4.0. The technique provides a method of determining the number-average translational diffusion coefficient) $\text{D}\text{?}{}_{\mathrm{n}}$, of association colloids and leads, via the Stokes-Einstein relation, to a measure of the number-average of the reciprocal hydrodynamic radius $\text{(R}{}_{\mathrm{<mtext>D</mtext><mtext>?</mtext>}}{}^1\text{)}{}_{\mathrm{n}}$ for spherical particles. Particles having a radius less than approximately 30 nm were too small to be detected by the technique.The ultramicroscopy results were compared with data obtained by laser light scattering photon correlation spectroscopy which provides a measure of the z-average translational diffusion coefficient. $\text{D}\text{?}{}_{\mathrm{z}}$. An additional comparison was made by carrying out measurements on two well-characterized poly(styrene/divinyl benzene) latices.