Poly(butylene succinate)/poly(vinyl phenol) blends. Part 1. Miscibility and crystallization

Miscibility has been investigated in blends of poly(butylene succinate) (PBSU) and poly(vinyl phenol) (PVPh) by differential scanning calorimetry in this work. PBSU is miscible with PVPh as shown by the existence of single composition dependent glass transition temperature over the entire composition range. In addition, the polymer–polymer interaction parameter, obtained from the melting depression of PBSU using the Nishi–Wang equation, is composition dependent, and its value is always negative. This indicates that PBSU/PVPh blends are thermodynamically miscible in the melt. Preliminary morphology study of PBSU/PVPh blends was also studied by optical microscopy (OM). OM experiments show the spherulites of PBSU become larger with the PVPh content, indicative of a decrease in the nucleation density, and the coarseness of PBSU spherulites increases too with increasing the PVPh content in the blends.     

溶剂对维生素C单晶生长动力学的影响

引　言当过饱和溶液中产生晶核或加入晶种时 ,溶质分子在过饱和度的推动下使晶核或晶种长大的过程就是晶体生长 .晶体生长动力学决定了晶体产品的形态及其物理性质 ,是结晶过程设计、优化和操作的基础 ,在结晶过程研究中占有重要地位[1,2 ] .晶体生长的外部条件例如过饱和度、温度、溶剂等都直接影响到晶面吸附情况的变化、晶体比表面自由焓 ,从而影响晶面的生长速度[3,4 ] .单晶研究是借助于显微镜、照相机、衍射仪等观察手段测定单晶各方向的尺寸随时间的变化 ,确定晶体生长动力学的方法[5] .作者曾采用间歇动态法实验测试维生素C在水 乙…     

基于Pro／E参数化斜齿轮建模技术

应用Pro／E软件的参数化造型功能，不需要二次开发，直接创建渐开线斜齿圆柱齿轮模型，对直齿、人字齿齿轮的建模具有借鉴作用。     

新法合成1，4－二羟基－2－萘甲酸

新法合成１，４ 二羟基 ２ 萘甲酸，操作简便，溶剂消耗少，反应时间短，收率高。探索了影响反应产率的几种因素。     

用KOH提取重组大肠杆菌中的PHA

用碱消化法从重组大肠杆菌中提取了PHA. 研究了碱液浓度、温度、消化时间及消化过程液固比等参数对产品PHA质量的影响. 提出了二段消化工艺,提高了PHA的产品纯度,所得PHA产品纯度为98.3%,同时较大幅度地降低了PHA的提取成本.     

Parameter Estimation for Periodically Stationary Time Series

Abstract. The innovations algorithm can be used to obtain parameter estimates for periodically stationary time series models. In this paper, we compute the asymptotic distribution for these estimates in the case, where the innovations have a finite fourth moment. These asymptotic results are useful to determine which model parameters are significant. In the process, we also develop asymptotics for the Yule–Walker estimates.     

耐药大肠杆菌的致病性与免疫原性

目的了解大肠杆菌耐药株的致病性与免疫原性。方法临床分离耐药大肠杆菌,经适宜条件培养后接种小鼠,观察耐药菌株对小鼠的致病性;并选择已知血清型的不同耐药谱和不同耐药水平的菌,分别培养至对数生长期,经甲醛灭活后免疫小鼠,2周后分别用致死剂量的原菌株和同期分离菌株进行攻毒,考察耐药菌株免疫原性。结果24株耐药菌普通肉汤培养物分别感染小鼠,在接种后18h,存活率仅为4%。只有2株菌在1周内仍不能将小鼠全部致死,经小鼠体内传3代后,可在18h内致死小鼠。耐药谱广的菌株感染的小鼠,心肌发生颗粒变性、局灶性出血、坏死;肝脏糖元溶解,脂肪变性;脾脏轻度淤血,淋巴细胞减少;肾脏出血,肾小球肾炎,上皮细胞颗粒变性,水泡变性。而耐药种类少的菌株与对照敏感菌株感染的小鼠主要特征为脾脏出血、淤血,坏死,脾小体消失;肠上皮细胞坏死、脱落、卡他性肠炎。免疫小鼠以免疫用菌株攻毒,均可得较高的保护率,最低为75%,最高为100%。免疫小鼠用非免疫菌株攻毒,小鼠感染后症状出现较缓慢,在18h后出现死亡高峰。耐药种类少的菌株免疫小鼠,对同期分离的非免疫用的致病性大肠杆菌攻击的保护率偏低,而对受试的11种抗生素耐受7种以上的菌株免疫小鼠后,对致病大肠杆菌攻击的保护率显著提高,多数达到75%以上,经统计学分析差异显著。结论耐药大肠杆菌具有较强致病性,且耐药特性与其免疫保护效果相关,多重耐药株对当前流行菌株具有更好的免疫保护作用。     

Phenol adsorption on porous and non-porous carbons

Phenol physisorption on a series of porous and non-porous amorphous carbons was studied at 298 K. Grand Canonical Monte Carlo computer simulations were performed to simulate phenol adsorption from the gas phase. Phenol is adsorbed in a solid-like state within the pores and there is no well-developed multilayer regime. The ‘t’ plot method was adapted to phenol adsorption and the results obtained are in agreement with the model solids employed. The simulated adsorption isotherms were compared with experimental results obtained for adsorption from aqueous solutions of phenol. BET surface areas were calculated. Other characteristics of the adsorption system analyzed were: adsorption energy distribution functions, density profiles, distribution of molecules according to gas-solid energy, and local isotherms.     

硫酸氢钠催化合成丁二酸二乙酯

在一水硫酸氢钠存在下 ,由乙醇和丁二酸合成了丁二酸二乙酯。当丁二酸、乙醇和硫酸氢钠的物质的量比为 1∶ 6∶ 0 .2 ,环己烷为溶剂 ,回流分水 5 0 m in,酯收率达 80 .5 %     

基于AD7884的分离脱落电连接器机械分离力测试台的设计

基于分级型模数转换器AD7884对分离脱落电连接器的分离力进行测量,采用8位单片机W77E58与之接口,进行数据处理并通过485串口传输到上位机。实现了对分离脱落电连接器的分离力进行测量,系统运行稳定,且与上位机数据交互简单、可靠。