Confined State and Electronic Transport in an Artificial Graphene-Based Tunnel Junction

Artificial graphene structures embedded in semiconductors could open novel routes for studies of electron interactions in low-dimensional systems. We propose a way to manipulate the transport properties of massless Dirac fermions in an artificial graphene-based tunnel junction. Velocity-modulation control of electron wave propagation in the different regions can be regarded as velocity barriers. Transmission probability of electron is
affected profoundly by this velocity barrier. We find that there is no confinement for Dirac electron as the velocity ratioξ is less than 1, but when the velocity ratio is larger than 1 the confined state appears in the continuum band. These localized Dirac electrons may lead to the decreasing of transmission probability.     

Microscopic Theory of Nonlinear Spin Waves in Ferromagnets

Considering the attractive interaction between two magnons with opposite wave vectors in a Heisenberg ferromagnet, we propose the model of magnon-pairs, which is suitable for low-temperature environment. A dressed magnon is an energy quantum of the magnon-pairs whose energy is a monotonically
increasing function of absolute temperature. Based on the model, we re-investigate the excitation mechanism and thermodynamic properties of the Heisenberg ferromagnet. The correction factore(0) plays an important role in studying the low-temperature properties of a ferromagnet.     

苏氨酸和谷氨酸在d318树脂上的吸附分离热力学

阴离子交换树脂;苏氨酸;谷氨酸;吸附分离;热力学性质     

压力下氯化钠型SnAs结构和电子性质的密度泛函理论研究

基于第一性原理计算方法研究了压力对氯化钠型SnAs结构和电子特性的影响。计算结果表明,晶格参数随着压力的增加而减小;状态密度显示随着压力的增加,As-p态的减小导致了SnAs 电导率降低。通过对电荷密度和Mulliken重叠布居的研究,分析了Sn和As原子之间的键合情况,表明了SnAs中共价键随着压力的增加而增强。进一步分析得知费米能级电子态密度的降低,可能导致了Tc的降低。     

稀酸处理稻草LCC的光谱研究

在提取纯化稻草木质素-碳水化合物(LCC)基础上,模拟稀硫酸糖化过程处理LCC,对稀酸处理前后产物进行FTIR和HPLC分析,研究稀酸糖化过程中LCC结构变化。研究结果表明:稻草LCC中部分碳水化合物稀酸糖化过程中不稳定,易发生降解,处理产物液相中主要组分为木糖和葡萄糖,残余物中LCC中部分碳水化合物对稀酸具有一定的稳定性。     

β-衰变中容许跃迁和禁戒跃迁的衰变规律

在考虑容许跃迁和禁戒跃迁的基础上, 对远离β稳定线附近原子核的β^-衰变寿命进行了系统的研究, 发现对于远离β稳定线的原子核的β^-衰变寿命, 其容许跃迁和禁戒跃迁寿命(T_1/2)与母核的质子数和中子数之间存在指数规律. 利用这个规律, 计算了β^-衰变中的容许跃迁和禁戒跃迁(包括一级禁戒跃迁和二级禁戒跃迁)的衰变寿命, 理论计算结果与实验值符合得很好. 在此基础上, 对于一些核素的β^-衰变寿命进行预言, 这对于核物理和天体物理中β^-衰变研究具有重要意义.     

First-principles study of the structural,elastic, mechanical,electronic, and optical properties of cubic Mg<Subscript>2</Subscript>TiO<Subscript>4</Subscript>

We have performed ab-initio total energy calculations using the plane-wave ultrasoft pseudopotential technique based on the first-principles density-functional theory (DFT) to study structural, elastic, mechanical, electronic, and optical properties of cubic Mg₂TiO₄. The calculated lattice parameter a is in good agreement with the experimental values. The independent elastic constants are calculated. The mechanical properties including bulk, shear and Young’s modulus, Poisson’s coefficient, compressibility and Lamé’s constants are obtained using the Voigt-Reuss-Hill method. Debye temperature is estimated using the Debye-Grüneisen model. Band structure, density of states and charge densities are shown and analyzed. In order to clarify the mechanism of optical transitions of cubic Mg₂TiO₄, the complex dielectric function, refractive index, extinction coefficient, reflectivity, absorption coefficient, loss function and complex conductivity function are calculated.     

Development and characterization of an amperometric sensor for triclosan detection based on electropolymerized molecularly imprinted polymer

A novel amperometric sensor based on electropolymerized molecularly imprinted polymer (MIP) for triclosan detection is reported. The sensor was prepared by electropolymerizing o-phenylenediamine (o-PD) on a glassy carbon electrode in the presence of template triclosan. The template can be quickly removed by NaOH solution. After incubating in acetate buffer for 15 min, the sensor response sensitively to triclosan over a linear range of 2.0 × 10^{− 7} to 3.0 × 10^{− 6} mol/L and a detection limit as low as 8.0 × 10^{− 8} mol/L is obtained. This sensor provides an efficient way for eliminating interferences from compounds with similar structures to that of triclosan.     

Finite-size corrections to the radiation laws of a Kerr nonlinear blackbody

In a Kerr nonlinear blackbody (KNB), bare photons with opposite wave vectors and helicities are bound into pairs and unpaired photons are transformed into nonpolaritons. The nonpolariton system can constitute free thermal radiation in the blackbody. The present paper investigates the radiation of a KNB in a cavity of finite-size. For a given geometry, we obtain explicit expressions of the modified Planck and Stefan-Boltzmann blackbody radiation laws as a function of the temperature, size and shape of the cavity by using semiclassical techniques. Moreover, we discuss these corrections of a spherical KNB and the range of parameters (temperature and size of the cavity) in which these effects are accessible to experimental detection. Finally, we calculate the finite-size corrections (FSCs) under these conditions, and this work may lay the foundation for the experimental verification of a KNB.     

Klein Paradox and Disorder-Induced Delocalization of Dirac Quasiparticles in One-Dimensional Systems

Dirac particle penetration is studied theoretically with Dirac equation in one-dimensional systems. We investigate a one-dimensional system with N barriers where both barrier height and well width are constants randomly distributed in certain range. The one-parameter scaling theory for nonrelatiyistic particles is still valid for massive Dirac particles. In the same disorder sample, we find that the localization length of relativistic particles is always larger than that of nonrelativistic particles and the transmission coefficient related to incident particle in both cases fits the form T～ exp（-αL）. More interesting, massless relativistic particles are entirely delocalized no matter how big the energy of incident particles is.