Ab initio calculations on the mechanism of isobutane and 2-butene alkylation reaction catalyzed by hydrofluoric acid

Ab initio method was employed to determine the mechanism of alkylation reaction of 2-butene with isobutane. The results indicated that 2-butene is rapidly protonated to form sec-butyl carbonium ion, which then reacts with isobutane to form tert-butyl carbonium ion. The resulting carbonium ion is then deprotonated to form isobutene that reacts rapidly with tert-butyl carbonium ion to form trimethylpentane (TMP) carbonium ion. Finally, the TMP⁺ carbonium ion is converted to TMP via the hydride transfer process. The transition states of the interactions were obtained by using the SCAN method (a calculation key word for potential energy surface) first and then the intrinsic reaction coordinates were traced using the Gaussian program. In addition, the energy changes and geometric parameters of the interactions were analyzed. The computed results indicated that the energy barriers are close to or less than zero for the interaction of isobutane with protonated 2-butene or for the interaction of tert-butyl carbonium ion with isobutene, suggesting rapid reaction steps of the carbonium ions. The 2,2,3-TMP is kinetically controlled, while the formation of 2,2,4-TMP is controlled by reaction equilibrium. The calculated results were in good agreement with the experimental results.     

The summary of researches on ADS in China

The conceptual study on the accelerator driven system (ADS) that lasted for about five years ended in 1999 in China. As one project of the National Basic Research Program of China (973 Program) in the energy domain, which is sponsored by the China Ministry of Science and Technology (MOST), a five-year-program of fundamental research of ADS physics and related technology was launched in 2000 and passed national review at the end of 2005. The China Institute of Atomic Energy (CIAE), the Institute of High Energy Physics (IHEP), the Institute of Heavy Ion Physics in Peking University (PKU-IHIP) and other institutions jointly carried out the research. The research activities were focused on HPPA physics and technology, reactor physics of external source driven sub-critical assembly, nuclear data base and material study. For HPPA, a high current injector consisting of an ECR ion source, LEBT and an RFQ accelerating structure of 3.5 MeV was built. In reactor physics study, a series of neutron multiplication experimental study has been carried out and still being done. The VENUS facility has been constructed as the basic experimental platform for neutronics study in ADS blanket. It’s a zero power sub-critical neutron multiplying assembly driven by external neutron produced by a pulsed neutron generator. The theoretical, experimental and simulation study on nuclear data, material properties and nuclear fuel circulation related to ADS is carrying on to provide the database for ADS system analysis. The main results on ADS related researches will be reported.     

泡沫沥青混合料动态性能研究

为更好地模拟泡沫沥青混合料在车辆动载作用下的动态性能，便于与国外相关研究进行比较，采用劈裂法对混合料动态性能进行研究。通过试验研究骨料类型、级配、水泥用量等对泡沫沥青混合料动态回弹模量的影响，总结了泡沫沥青混合料动静模量的关系。     

考虑渗流力的基坑涌砂分析

本文根据基坑防渗帷幕周围的地下水渗流特征，分析了渗流力对基坑流砂的影响，提出了按涌砂安全系数进行防渗帷幕埋入深度计算的方法。     

Electron microscopic observations and DNA chain fragmentation studies on apoptosis in bone tumor cells induced by ~(153)Sm-EDTMP

ＥｌｅｃｔｒｏｎｍｉｃｒｏｓｃｏｐｉｃｏｂｓｅｒｖａｔｉｏｎｓａｎｄＤＮＡｃｈａｉｎｆｒａｇｍｅｎｔａｔｉｏｎｓｔｕｄｉｅｓｏｎａｐｏｐｔｏｓｉｓｉｎｂｏｎｅｔｕｍｏｒｃｅｌｓｉｎｄｕｃｅｄｂｙ１５３ＳｍＥＤＴＭＰＺｈｕＳｈｏｕＰｅｎｇ，Ｘｉａ...     

光纤中二次谐波的产生及机理的电镜分析

本文报导了石英光纤中的二次谐波产生及用透射电子显微镜观察光纤内部物质结构变化的实验结果,观察到了已“预置”光纤中缺陷的存在.     

上向分层尾砂充填法在仓上金矿的新应用

本文介绍了垂直矿体走向布置的上向分层尾砂充填采矿法新方案的特点及其在仓上金矿中厚矿体的具体应用。     

贝氏体钢内水冷穿孔顶头的粘钢及防止措施

从顶头生产工艺控制的角度,分析了贝氏体钢内水冷穿孔顶头产生粘钢的原因、特点和机制,指出掉鼻、缺肉是顶头粘钢的另一种更为严重的失效形式,强化熔炼工艺控制和保证夹杂物总量在A0.5B1C0.5D1级水平,粘钢问题可以得到有效控制。     

船舶管系减振材料的应用研究

为适应我国舰船减振降噪的需要，试制出ＱＧＤ－１和ＱＧＤ－２两种穿孔型隔振垫，主要用于管路马脚，也可用于基座等振动部位。对两种隔振垫的阻尼性能、阻燃性能、耐油性能与国外同类产品进行了比较。经管路模型试验和水泵机组试验证明，这两种隔振垫可使管路系统振动加速度级明显下降。     

环境放射化学研究中几个问题的讨论

本文从辐射环境保护和公众辐射防护的角度，讨论了放射性核素在环境中的迁移行为，放射性核素与环境介质的相互作用和放射性核素在环境中的形态等涉及到环境放射化学研究方向的问题，并讨论了它们之间相互依存的关系。