SO3H-功能化离子液体的合成及用于催化酯化反应的研究

采用两步法制备了一种基于4-二甲氨基吡啶(DMAP)的SO3H-功能化Brnsted酸性离子液体,并将其应用于催化1,4-丁二醇与乙酸的酯化反应。DMAP与1,3-丙烷磺酸内酯(PS)反应生成单一的两性离子化合物,收率接近100%。该离子液体对1,4-丁二醇与乙酸的酯化反应催化活性较高,在温度为40℃时酯化率可达88.1%,选择性为100%,催化剂易与产物分离,且可以循环使用。     

锂 - 氧化铜电池及其反应机理

本文研究了Li/CuO电池和Li/CuO电池的一般放电行为,着重探讨了它们的反应机理。X射线衍射分析、ESR分析、XPS分析和循环伏安试验等结果表明,电池反应的实质是锂在正极内进行电化学嵌入反应,并在一定嵌入度后因Cu—O键断裂而析出金属铜。其化学反应式可表达为: xLi+CuO(Cu_2O)→Li_xCuO(Li_xCu_2O)(a) x_1Li+Li_xCuO(Li_xCu_2O)→ Li_(x+x_1)Cu_(1-y)O(Li_(x+x_1)CU_(2-y)O)+yCu (b) 用电化学暂态方法测得嵌入锂离子在正极内部的化学扩散系数约为2×10~(-12)cm~2·s~(-1)(室温),该值与在Li_xWO_3和Li_xTiO_2中的相近,与实际电池的放电速率是一致的。     

微阵列芯片的荧光光漂白特性

微阵列技术为大量基因表达水平的同时监控提供了一种高效的手段。随着微阵列芯片朝着小型化、高通量和弱信号方向发展,荧光检测技术以其易寻址和高灵敏度等优势越来越受到世人关注。在微阵列技术中,人们通过检测微阵列芯片上不同位置斑点的荧光信号强度,可以得知微阵列芯片不同位置固定的已知序列探针与荧光染料标记的cDNA样品的杂交情况。对一张微阵列芯片多次扫描后,荧光染料发生光漂白,荧光强度发生衰减变化,它将为微阵列的数据分析带来误差。使用荧光浓度梯度微阵列芯片研究了芯片经多次扫描后荧光斑点强度的衰减情况,通过拟合相同荧光斑点经多次重复扫描后得到的信号强度,得到了荧光斑点强度按指数形式衰减的规律,并在此基础上研究了荧光斑点强度衰减指数模型中的参数与荧光斑点初始浓度的关系,为进行微阵列芯片数据光漂白误差修正提供了实验依据。     

爱丁顿、钱德拉塞卡关于白矮星的争论及其启示

对爱丁顿、钱德拉塞卡关于白矮星的争论作了介绍,讨论了这场争论和钱德拉塞卡的科研风格带给我们的启示．     

Temperature Properties in Polydisperse Granular Mixtures

Numerical simulations are employed to consider the problem of determining the granular temperatures of the species of a homogeneous heated granular mixture with a power-law size distribution. The partial granular temperature ratios are studied as functions of the fractal dimension D, the restitution coefficient e, the rescaled viscosity time, the average occupied area fraction φ, the total particle number N and the number fraction. Different species of particles in a power-law system typically do not have the same mean kinetic energy, namely the granular temperature. It is found that the extent of nonequipartition of kinetic energy is determined by the fractal dimension D, the restitution coefficient e and the rescaled viscosity time, while is insensitive to the total particle number N , the area fraction φ and the number fraction.     

H2的自由扩散和吸附状态的对比研究

运用巨正则Monte Carlo方法, 模拟了H₂在自由扩散状态下及碳纳米管吸附状态下的分布, 对H₂的自由扩散和吸附状态进行了对比研究. 研究表明: 77 K和2 MPa下, (30, 30)扶手椅型碳纳米管质量储氢密度为3.74%, 77 K和10 MPa下, 质量储氢密度为7.4%. 吸附状态的H₂分子主要汇聚在碳纳米管内外两个壁面. 关键词： 储氢 碳纳米管 巨正则Monte Carlo     

计算实对称矩阵特征值特征向量的幂法

幂法是一种计算实矩阵主特征值的一种迭代方法,在幂法的基础上进行了扩展,提出了一种能计算实对称矩阵所有特征向量和特征值的迭代方法,并对该方法的收敛性进行了证明,最后通过数值实验验证了该方法的有效性。     

Charge noise acting on graphene double quantum dots in circuit quantum electrodynamics architecture

We investigate the dephasing mechanisms induced by the charge noise and microwave heating effect acting on a graphene double quantum dot(DQD) capacitively coupled to a microwave resonator. The charge noise is obtained from DC transport current, and its contribution to dephasing is simultaneously determined by the amplitude response of the microwave resonator. A lowfrequency 1/f-type noise is demonstrated to be the dominant factor of the dephasing of graphene DQD. Furthermore, when the applied microwave power is larger than-90 d Bm, the dephasing rate of graphene DQD increases rapidly with the increase of microwave power, and fluctuates slightly with the applied microwave power smaller than-90 d Bm. Our results can be applied to suppress the impeditive influence on the dephasing of graphene-based devices associated with microwave input in the perspective investigations.     

Spin manipulation in semiconductor quantum dots qubit

Thirty years of effort in semiconductor quantum dots has resulted in significant developments in the control of spin quantum bits(qubits). The natural two-energy level of spin states provides a path toward quantum information processing. In particular, the experimental implementation of spin control with high fidelity provides the possibility of realizing quantum computing. In this review, we will discuss the basic elements of spin qubits in semiconductor quantum dots and summarize some important experiments that have demonstrated the direct manipulation of spin states with an applied electric field and/or magnetic field. The results of recent experiments on spin qubits reveal a bright future for quantum information processing.     

阳射线研究简史

人们在回顾气体放电研究的历史时,对阴极射线作过详尽的探讨,但对阳射线（ｐｏｓｉｔｉｖｅｒａｙｓ）研究的历史,却很少有人注意,实际上,这段鲜为人知的历史,对原子物理学的进展,有着极为重要的意义,本文所讨论的正是这项研究的简要历史。一、阳射线的早期研究１８８６年,德国物理学家戈德斯坦（Ｅ。Ｇｏ?...