三苯基膦和亚磷酸酯类配体在双环戊二烯氢甲酰化反应中的对比研究

以具有不同取代基的三苯基膦和亚磷酸酯为配体,铁磁性的钴铑双金属为催化剂,考察双环戊二烯氢甲酰化合成三环癸烷不饱和单醛的反应。结果表明,反应存在一定的诱导期,诱导期越短,反应速率越快;配体上的取代基对反应活性和产物选择性具有显著影响,吸电子取代基催化活性较高,诱导期较短,反应速率较快,但选择性较低。亚磷酸酯配体中以亚磷酸三苯酯效果最好,与三苯基膦相比,转化率和选择性均相对较低。在考察的配体中,三苯基膦作为配体,三环癸烷不饱和单醛选择性最高,达97%。     

气象预警管理系统在宁夏农村防灾减灾中的应用

以LED电子屏和语音大喇叭的气象预警管理系统在宁夏农村防灾减灾建设中的研究为背景,介绍该系统的结构、功能和特点,以及使用中存在的问题和对策等.该气象预警管理系统基于C/S架构,结合了LED气象预警电子屏终端和语音大喇叭,主要实现面向LED电子屏及大喇叭的气象预报、预警信息编辑、录入、审核、发布与GPRS终端管理等功能,为宁夏农村气象信息服务和防灾减灾服务提供安全、快捷、有效的发布管理平台.     

Energetic analysis of binding of progesterone and 5{beta}-androstane-3,17-dione to anti-progesterone antibody DB3 using molecular dynamics and free energy calculations

Molecular dynamics simulations and molecular mechanics–Poisson–Boltzmannsurface area (MM-PBSA) free energy calculations were used tostudy the energetics of the binding of progesterone (PRG) and5ß-androstane-3,17-dione (5AD) to anti-PRG antibodyDB3. Although the two steroids bind to DB3 in different orientations,their binding affinities are of the same magnitude, 1 nM forPRG and 8 nM for 5AD. The calculated relative binding free energyof the steroids, 8.8 kJ/mol, is in fair agreement with the experimentalenergy, 5.4 kJ/mol. In addition, computational alanine scanningwas applied to study the role of selected amino acid residuesof the ligand-binding site on the steroid cross-reactivity.The electrostatic and van der Waals components of the totalbinding free energies were found to favour more the bindingof PRG, whereas solvation energies were more favourable forthe binding of 5AD. The differences in the free energy componentsare due to the binding of the A rings of the steroids to differentbinding pockets: PRG is bound to a pocket in which electrostaticantibody–steroid interactions are dominating, whereas5AD is bound to a pocket in which van der Waals and hydrophobicinteractions dominate.     

Surface wettability and flow properties of non-metallic pipes in laminar flow

In this paper, three liquids flowing in five pipes with the same inner diameter of 14 mm were studied to determine the relationship between the surface wettability and flow properties in laminar flow(Re b 2000). This was motivated by oilfield observations of increased pressure drops in non-metallic pipes compared to those in metal pipes,which was contrary to expectations. A new expression for the frictional coefficient that considers the Reynolds number and contact angle θ in laminar flow for non-metallic pipes was proposed based on the experimental results of single-phase flow using dimension and regression analyses. The solutions of the anomalous phenomenon were proposed from the perspectives of the pipe diameter, contact-angle difference, and the compatibility between flexible composite pipe and JLHW105 oil according to the new formula. The surprising finding was that the surface wettability could control the frictional resistance by the critical contact angle(39.9°) obtained at the same Reynolds number. If 0° b θ≤ 39.9°, the frictional coefficient increased as the contact angle increased. In contrast, if 39.9° b θ b 180°,the frictional coefficient decreased with increasing contact angle. The influences of the pipe diameter and contactangle difference on the pressure drop difference of JLHW105 oil showed an inversely proportional relation. A series of materials and liquids were tested. The selection of pipe material for transporting a given fluid can be based on the contact angle, surface tension, and critical limit of the contact angle obtained. The research results are expected to provide some guidelines for the selection of the appropriate pipe material for a given set of fluids.     

隔膜中残油量对锂电池性能的影响

锂离子电池隔膜在锂离子电池中主要起隔绝正负极防止短路和允许锂离子导通的作用[1],因此,锂离子电池隔膜品质的优劣直接影响到锂离子电池的应用性能。在锂电池隔膜制备的过程中,以石蜡油作为造孔剂,用热致相分离法制备聚乙烯微孔膜,石蜡油的残留不可避免。本文研究了隔膜中石蜡油的残留量对电池自放电、倍率放电、高温存储、循环性能等应用性能的影响。研究结果表明,残油量越低锂电池的应用性能越优。     

连续挤压大宽厚比产品的物理模拟实验研究

针对连续挤压大宽厚比产品中易出现的裂边等产品质量问题,进行模具设计。传统塑性加工实验易造成材料浪费且不易操作,实验采用橡皮泥作为模拟材料,对所设计模具进行物理模拟,并依据模拟结果对模具进行改进。结果表明,改进后的模具具有良好的材料成形性,产品裂边问题得到有效控制。     

草莓型P(St-BA)/SiO_2纳米复合微球制备与表征

在混合溶剂丙酮/水介质中,以纳米SiO_2粒子为Pickering乳化剂,阳离子单体甲基丙烯酰氧乙基三甲基氯化铵(MTC)为辅助单体,苯乙烯(St)和丙烯酸丁酯(BA)发生无皂乳液聚合制备了固含量高达25%的草莓型P(St-BA)/SiO_2纳米复合微球。研究了初始硅溶胶用量、软硬单体配比对复合微球形态、粒径和SiO_2吸附量的影响,并测试了乳胶膜的吸水性能。结果表明:在实验范围内制备得到的复合微球粒径在290～560 nm之间,SiO_2的吸附量介于28～34wt%之间。     

具有间隙的风力机变桨距系统模糊自整定PID控制

因加工、安装和磨损的原因,大型风力机的变桨距电液控制机构铰链处不可避免的存在间隙,过大的间隙会使得变桨过程超调量增大,调节过程震荡次数过多,甚至引起叶片与塔架共振,最终导致风力机停机事故。分析了变桨距机构铰链处间隙的形成机制,提出了用模糊自整定PID控制算法对间隙进行补偿的方法,依据间隙的振-冲模型制定模糊推理规则,对PID控制器参数进行自适应整定。在间隙分别为0.2、0.4、0.6和0.8 mm时对常规PID控制器与模糊自整定PID控制性能进行对比研究。结果表明:相比常规PID控制器,模糊自整定PID控制方法使得变桨距控制系统超调量和震荡次数显著减小,有效地避免了系统变桨冲击。     

硬态切削工件表面白层厚度预测方法

硬态切削过程中产生了高的机械载荷和热载荷,工件表面易产生白层组织,研究硬态切削工件表面白层的形成机理并对白层厚度进行建模预测,对于改善硬态切削加工技术具有指导意义。以探究白层形成机理为研究目标,综合运用弹塑性力学、热力学和材料相变理论,建立热力耦合的硬态切削模型,模拟了硬态切削过程中的温度场和应力场,分析了工件表面白层形成的组织转变过程,以热力影响下的材料相变温度作为白层形成的判据,建立了白层厚度的预测方法,并以轴承钢GCr15为研究对象,预测了不同切削参数下白层的厚度,对预测结果加以对比验证。研究结果表明:对于硬态切削工件表面白层的形成,基于相变理论的白层厚度预测方法是可行的。     

高压电气产品铝合金支架铸件的工艺优化

高压电气铝合金支架铸件,原工艺采用金属型树脂砂芯倾转铸造一模一件,由于产品需求量激增,质量要求逐渐提高,现有的一模一件倾转模具已满足不了客户需求。通过优化工艺方案,采用金属型低压铸造(取消树脂砂芯)一模八件的生产方式,大大提高了铸件的生产效率和工艺出品率,并降低了成本。