磁性硅烯超晶格中电场调制的谷极化和自旋极化

研究了基于硅烯的静电势超晶格、铁磁超晶格、反铁磁超晶格中谷极化、自旋极化以及赝自旋极化的输运性质,分析了铁磁交换场、反铁磁交换场以及化学势对输运性质的影响,讨论了电场对谷极化、自旋极化以及赝自旋极化的调控作用.结果表明:当3种超晶格的晶格数达到10以上时,在硅烯超晶格中很容易实现100%的谷极化、自旋极化和赝自旋极化,而且通过调节超晶格上的外加电场可以使极化方向发生翻转,从而在硅烯超晶格中实现外电场对谷自由度、自旋自由度以及赝自旋自由度的操控.     

柠檬酸在烟草上的吸附性能研究

采用静态法，研究了柠檬酸在烟草上的吸附和解吸附性能以及共存物质对吸附能力的影响，测定了在不同浓度、温度下的吸附速率曲线和吸附等温线，并估算出吸附热。结果表明，柠檬酸在烟草上的吸附量大，吸附速率快，属物理吸附。当柠檬酸的浓度小于0．005mol/L时，吸附等温线呈直线型；而当柠檬酸的浓度增大到0．15mol/L的范围内时，吸附等温线则呈现典型的“台阶”型。     

Hg_2、Hg_2~(2 )、Hg_3、Hg_3~(4 )原子簇的电子结构和光谱的SCC-DV-X_α方法的计算

利用ＳＣＣ－ＤＶ－Ｘα方法计算了Ｈｇ２、Ｈｇ２＋２、Ｈｇ３、Ｈｇ４＋３原子簇的电子结构和光谱，分析了体系的稳定性和影响分子轨道的因素及可能的光谱跃迁波长，所得结果与所报道的实验结果作了比较。     

Short-Time Dynamical Behaviour of Depinning Transition in the Uniformly Frustrated Two-Dimensional XY Model

A short-time dynamic scaling approach is extended to study the depinning transition of the two-dimensional frustrated XY model driven by external currents. We investigate the scaling behaviour of depinning transition in the XY model with three different flux densities f = 1/2, 1/25, 1/30. The short-time scaling behaviour in the depinning transition of the two-dimensional XY model is clearly shown up. Besides the critical current, the exponent θ is obtained.     

分子对接模拟与多光谱法研究二水土霉素和牛血清白蛋白的相互作用

在模拟生理条件下,采用荧光光谱法、三维荧光光谱法、圆二色谱法以及分子对接模拟法,研究了二水土霉素与牛血清白蛋白(BSA)之间的相互作用。荧光光谱表明,二水土霉素能有效猝灭BSA的内源荧光,猝灭机制属静态猝灭。根据Vant’s Hoff方程确定结合过程中的热力学参数ΔS、ΔH,表明两者之间作用为疏水作用力。根据Foster’s非辐射能量转移理论,计算得到结合距离r=2.56nm。同步荧光光谱、三维荧光光谱、圆二色谱结果证明盐酸四环素能够改变BSA的二级结构和微环境。分子对接模拟表明二水土霉素结合在BSA的site Ⅰ(亚域ⅡA)疏水腔中。     

Sign reversal of anisotropic magnetoresistance and anomalous thickness-dependent resistivity in Sr2CrWO6/SrTiO3 films

High-quality Sr₂CrWO₆ (SCWO) films have been grown on SrTiO₃ (STO) substrate by pulsed laser deposition under low oxygen pressure. With decrease of the film thickness, a drastic conductivity increase is observed. The Hall measurements show that the thicker the film, the lower the carrier density. An extrinsic mechanism of charge doping due to the dominance of oxygen vacancies at SCWO/STO interfaces is proposed. The distribution and gradient of carrier concentration in SCWO films are considered to be related to this phenomenon. Resistivity behavior observed in these films is found to follow the variable range hopping model. It is revealed that with increase of the film thickness, the extent of disorder in the lattice increases, which gives a clear evidence of disorder-induced localization charge carriers in these films. Magnetoresistance measurements show that there is a negative magnetoresistance in SCWO films, which is considered to be caused by the magnetic scattering of magnetic elements Cr³⁺ and W⁵⁺. In addition, a sign reversal of anisotropic magnetoresistance (AMR) in SCWO film is observed for the first time, when the temperature varies across a characteristic value, T_M. Magnetization—temperature measurements demonstrate that this AMR sign reversal is caused by the direction transition of easy axis of magnetization from the in-plane ferromagnetic order at T > T_M to the out-of-plane at T < T_M.     

PVP为模板控制合成球形碳酸钙

Spherical calcium carbonate was prepared by the reaction of sodium carbonate with calcium chloride at the presence of a protein-like molecule， polyvinylpyrrolidone， as the template. The products were characterized by elemental analyses， XRD， SEM， and TG-DSC respectively. The effects of polyvinylpyrrolidone on the crystal form and morphology of the as-prepared CaCO₃ were investigated. It was found that the aggregative shape of the produced calcium carbonate crystalline could be well controlled by adjusting the concentration of the polyvinylpyrrolidone template. This may be of important meanings to the biomimetic synthesis of novel inorganic materials.     

密度不同的颗粒在流体中的沉降特性

采用格子Boltzmann方法(LBM)对雷诺数范围为5≤Re≤12的双颗粒沉降进行了直接数值模拟研究,主要关注颗粒之间的密度差异k对其周期性振动的影响。根据雷诺数颗粒沉降特性可以分成三个阶段,即当Re较小时,颗粒的振动幅度随k的增大而减小,当Re较大时则正好相反,介于两者之间存在一个临界雷诺数,在此雷诺数附近,颗粒的沉降同时具有以上两种特征。同时还研究了两个颗粒的稳定沉降结构以及重颗粒摆脱轻颗粒的条件。