分子动力学模拟HEWL晶体在不同环境中的动力学行为

简要阐述分子动力学模拟的原理及步骤,介绍研究溶菌酶的一般方法和优缺点。在Ubuntu操作系统环境下,利用Gromacs软件和其自带的Gromos96力场,通过分子动力学模拟(MD)鸡蛋清溶菌酶晶体(chicken egg-whitelysozyme,HEWL)溶液,考察真空、水溶液和加入NaCl 3种不同环境条件对溶菌酶晶体构象动力学行为的影响,发现无论从均方根位移(rmsd)、回旋半径、还是从B因子值的轨迹图分析,HEWL在水溶液特别是加入抗衡离子(Na~+,Cl~-)的水溶液的环境下的结构更稳定、合理,与(protein data bank)数据库的真实情况相符。原因是Cl~-与溶菌酶晶体在界面处发生了吸附现象,局部形成溶菌酶-Cl~-复合物,抑制了蛋白-水合物中水分子在相邻水合位置间的跳跃,从而使单晶体在离子液态中更加稳定。模拟结果表明,在pH值6.5,等电位点13.1,总电荷7.999 6的体系下,影响HEWL的吸附位点为123号残基(色氨酸),对从分子水平上解释HEWL晶体的动力学吸附行为具有重要指导意义。     

磺基甜菜碱型两性离子聚合物的盐溶液性质

将甲基丙烯酰氧乙基二甲基胺(DM)和1,3-丙基磺内酯,在55℃下反应20 h,合成了2-(2-甲基丙烯酰氧乙基二甲胺基)磺酸盐(DMAPS),将其在盐溶液中与丙烯酰胺(AM)单体进行自由基共聚合反应,获得了净电荷为零的磺基甜菜碱型两性离子共聚物P (AM-DMAPS).对该两性离子共聚物进行了表征,利用紫外分光光度计、乌氏黏度计以及布氏黏度计对该聚合物的溶解性以及其盐溶液黏度进行了测定.研究结果表明,该共聚物在盐溶液中的黏度比在纯水中的大,并且随着盐溶液浓度的增大聚合物特性黏数也随之增大,表现出明显的反聚电解质溶液性质,且该共聚物在Mg2+、Ca2+盐溶液中的黏度相对于普通聚电解质更大;升高相同温度,两性共聚物的黏度保留率是普通聚丙烯酰胺的1.5倍.     

Synthesis of star polymethyl acrylate by SET-LRP at ambient temperature

The star-shaped polymethyl acrylate (PMA) was synthesized by single electron transfer living radical polymerization (SET-LRP) at 30 °C in dimethyl sulfoxide, using 2,2-dibromomethyl-1,3-dibromopropane as the multifunctional initiator, Cu⁰ powder and tris-(2-dimethylamino ethyl)amine (Me₆-TREN) as catalyst. The structure of polymer was analyzed by ¹H NMR, and the results showed that the star-shaped PMA had perfect chain ends (–Br) retention. In addition, the polymerization proceeded smoothly and the time dependence of ln([M]₀/[M]) was linear, which could indicate a first order propagation rate with respect to both radicals and monomer concentration, the polymerization was the living polymerization. The M _n and M _w/M _n of polymer were being measured by Gel Permeation Chromatography. The k _p^app = 0.0367 h⁻¹ and the conversion was 36.3% at 16 h, meanwhile the M _n^GPC of the polymer was 13,300 and the M _w/M _n was 1.40.     

露天液压钻车变幅机构运动学分析与工作空间研究

针对某型露天液压钻车对变幅机构进行了介绍,首先利用D-H法建立露天液压钻车变幅机构的坐标系,并采用齐次变换法,建立其运动学方程;选取变幅机构特定姿态,验证所得运动学方程的正确性;利用MATLAB进行编程计算,采用伪随机数法得到露天液压钻车变幅机构的可达工作空间、有效工作空间及有效工作范围的相关视图,并进行了三种工作空间的对比。全面系统的提出了露天液压钻车变幅机构运动学分析方法与相关工作空间的概念。     

Corrosion Inhibition Efficiency and Adsorption Behavior of the Branched Cationic Tetrameric Surfactant for Carbon Steel in HCl Medium

Protection of Metals and Physical Chemistry of Surfaces - The branched cationic tetrameric surfactant (4C14tetraQ) that the length of four hydrocarbon chains is 14 was synthesized, and the...     

溶聚丁苯橡胶种类对高填充白炭黑/溶聚丁苯橡胶复合材料性能的影响

研究端基改性和多官能化主链改性溶聚丁苯橡胶（SSBR）对高填充白炭黑/SSBR复合材料性能的影响。结果表明：4种SSBR胶料的门尼粘度基本相同;与端基改性SSBR相比,多官能化主链改性SSBR胶料的焦烧时间延长,硫化胶的硬度和定伸应力减小,填料分散性改善,Payne效应减弱,同时胶料的损耗因子明显降低。     

温度响应型蠕虫胶束体系抗盐性能研究

为提高温度响应型蠕虫胶束的抗盐性,采用阴离子表面活性剂十八烷基苯磺酸钠(SOBS)和两性离子表面活性剂十八烷基羟基磺基甜菜碱(ODAHPS)制得蠕虫胶束体系,研究了温度对胶束黏度的影响,考察了胶束的抗盐和抗碱性能。研究结果表明,当ODAHPS和SOBS的摩尔比为7时,胶束的响应温度为50℃;胶束黏度随着温度升高呈现先增加后降低的趋势;达到响应温度后,胶束黏度随表面活性剂总浓度的增加而增大;随角频率的增加,胶束溶液逐渐由黏性流体向弹性流体转变;胶束黏度随无机盐浓度的增加先增大后降低;胶束耐碱性能良好,当弱碱和强碱质量浓度分别为2.5 g/L和12 g/L时,胶束黏度分别为133和196 mPa·s,可以作为驱油剂使用。     

Effect of co-doped Tb<Superscript>3+</Superscript> ions on electroluminescence of ZnO:Eu<Superscript>3+</Superscript> LED

Rare earth (RE) -doped ZnO electroluminescence is worthy of investigation for phosphor-free white light-emitting diodes (LEDs) due to their pure and sharp emissions. Whereas, the low solubility of RE ions in ZnO films is found to hinder the performance of RE-doped ZnO devices. Herein, ZnO:Eu and ZnO:Eu/Tb LEDs were synthesized and the electroluminescence properties were tested. The results show that the emission intensity of ZnO: Eu/Tb LED is 8 times higher than that of ZnO: Eu LED while the input power is smaller when the concentration of terbium is proper. Furthermore, we discussed the excitation mechanism and found that the ratio of the EL intensity of the ⁵D₁ → ⁷F₁ to ⁵D₀ → ⁷F_{J (J=0???4)} transition increases with increasing Tb doping concentration, which may indicate the possibility of energy transfer from Tb³⁺ to Eu³⁺. The results are believed to be an effective strategy to improve the electroluminescence of RE-doped semiconductor for white LEDs.     

光纤测量技术在岩土工程中的应用

阐明了光纤测试技术相对于传统岩土工程测试技术的优点，简要介绍了两种典型光纤传感器——Fabry-Perot光纤传感器和Bragg光栅传感器的工作原理，通过试验证明了其可靠性，并通过国内外几个工程实例说明了光纤传感器的主要用途。     

奇数碳烷基间二甲苯磺酸钠在大庆油砂上的吸附

 摘要：考察了11种结构明确的奇数碳烷基间二甲苯磺酸钠(mCn-hS)在大庆油砂上的吸附,探讨了mCn-hS的初始质量浓度、分子结构、分子中烷基链长度及助剂对其吸附量的影响。结果表明,随着mCn-hS初始质量浓度的增大,其在大庆油砂上的吸附量先增大至饱和,后略有降低;烷基链长度相同的mCn-hS,随着其中芳基位置向烷基链中间位置移动,其在大庆油砂上的吸附量降低;NaCl和NaOH的加入使mCn-hS在大庆油砂上的吸附量增大,而异戊醇的加入使其降低;加入助剂后,随着mCn-hS分子中烷基链长度的增加,mCn-hS在大庆油砂上的吸附量减小。