SU(2)规范场的一系列“无源”解——静点磁荷系的SU(2)势及U(1)势

场与源这一对矛盾双方如何对立与统一是经典电磁场及引力场理论中议论纷云的一个根本问题.非Abel规范场的静无源解(应该说是无外源,但以场自身为源)提供了一个不含奇异点的、场与源互相制约构成自洽稳定的有机统一体的一个值得注意的例子(孤粒子).现有的这种解都是在无外源(实际上以场的奇异点——磁荷为源)的吴杨单位磁荷解([4]的情况a)的基础上加上径向“形状因子”得到的,因此只限于总磁荷为单位值(本文取Schwinger量子化值为磁荷单位)的静同步球对称情况.为了弄清楚更一般     

Zn Belavin模型反射方程的多参数解

利用A_(n－1)⁽¹⁾面模型反射方程的对角解,得到了ZnBelavin模型反射方程的含有n+1个参数的解.当n=2时,其结果与侯伯宇等人给出的8项角反射方程的解是一致的.     

中药白茅根中金属元素的含量测定

火焰原子吸收光谱法测定中草药白茅根茎部的Fe、Cu、Zn、Mn、Ca、Mg,方法简单、精密度好、回收率在92.0%-104.4%之间,相对标准偏差(RSD)小于1.8%,结果令人满意.     

显微镜工作台闭环控制系统的设计与实现

高精度工作台控制系统是现代自动显微系统的重要组成部分,其精度直接影响显微镜对样品的检测质量。介绍了一种基于AT89C52单片机的显微镜工作台闭环控制系统的设计方案。工作台移动时作为检测元件的光栅输出脉冲信号。单片机控制电路实现脉冲的计数并计算误差值,控制步进电机进行反馈补偿。步进电机通过细分驱动模块可以以四种不同的步距驱动工作台移动,以实现显微镜对工作台移动速度的不同需要。8位数码管实时显示工作台移动的实际位置。实验结果表明,该系统的重复定位精度可达到0.020mm,可满足显微镜对控制工作台的要求。     

New bifurcations of basin boundaries involving Wada and a smooth Wada basin boundary

This paper demonstrates and analyses double heteroclinic tangency in a three-well potential model, which can produce three new types of bifurcations of basin boundaries including from smooth to Wada basin boundaries, from fractal to Wada basin boundaries in which no changes of accessible periodic orbits happen, and from Wada to Wada basin boundaries. In a model of mechanical oscillator, it shows that a Wada basin boundary can be smooth.     

β-delayed neutron decay of 21N

The β-delayed neutron and γ spectra of neutron-rich nucleus ²¹N using β-γ and β-n coincidence measurements were presented in this paper. Thirteen new neutron groups ranging from 0.28 MeV to 4.98 MeV and with a total branching ratio 88.7±4.2% were observed. One γ transition among the excited states of ²¹O, and four γ transitions among the excited states of ²⁰O were identified in the β decay chain of ²¹N. The ungated half-life of 83.8±2.1 ms was also determined for ²¹N.     

An alternating periodic－chaotic ISI sequence of HH neuron under external sinusoidal stimulus

A study of Hodgkin－Huxley (HH) neuron under external sinusoidal excited stimulus is presented in this paper. As is well known, the stimulus frequency is to be considered as a bifurcate parameter, and numerous phenomena, such as synchronization, period, and chaos appear alternatively with the changing of the stimulus frequency. For the stimulus frequency less than 2f_B (f_B being the base frequency in this paper), the simulation results demonstrate that the single HH neuron could completely convey the sinusoidal signal in anti-phase into interspike interval (ISI) sequences. We also report, perhaps for the first time, another kind of phenomenon, the beat phenomenon, which exists in the phase dynamics of the ISI sequences of the HH neuron stimulated by a sinusoidal current. It is shown furthermore that intermittent transition results in the general route to chaos.     

Image charge effect on the light emission of rutile TiO_2(110) induced by a scanning tunneling microscope

The plasmon-enhanced light emission of rutile TiO_2(110) surface has been investigated by a low-temperature scanning tunneling microscope(STM). We found that the photon emission arises from the inelastic electron tunneling between the STM tip and the conduction band or defect states of TiO_2(110). In contrast to the Au(111) surface, the maximum photon energy as a function of the bias voltage clearly deviates from the linear scaling behavior, suggesting the non-negligible effect of the STM tip on the band structure of TiO_2. By performing differential conductance( dI/dV) measurements, it was revealed that such a deviation is not related to the tip-induced band bending, but is attributed to the image charge effect of the metal tip, which significantly shifts the band edges of the TiO_2(110) towards the Femi level(E_F) during the tunneling process. This work not only sheds new lights onto the understanding of plasmon-enhanced light emission of semiconductor surfaces, but also opens up a new avenue for engineering the plasmon-mediated interfacial charge transfer in molecular and semiconducting materials.     

Derivative of Electron Density in Non-Equilibrium Green's Function Technique and Its Application to Boost Performance of Convergence

The non-equilibrium Green＇s function （NEGF） technique provides a solid foundation for the development of quantum mechanical simulators. However, the convergence is always of great concern. We present a general analytical formalism to acquire the accurate derivative of electron density with respect to electrical potential in the framework of NEGF. This formalism not only provides physical insight on non-local quantum phenomena in device simulation, but also can be used to set up a new scheme in solving the Poisson equation to boost the performance of convergence when the NEGF and Poisson equations are solved self-consistently. This method is illustrated by a simple one-dimensional example of an N＋＋ N＋ N＋＋ resistor. The total simulation time and iteration number are largely reduced.     

理论研究F2BN3多聚体的结构特色和热力学稳定性

在密度泛函理论（DFT）B3LYP/6-311+G*水平上计算研究了叠氮二氟硼多聚体(F2BN3)n (n=1-4),获得了它们的结构和热力学性质,讨论了几何参数随聚合度的变化趋势。多聚体(F2BN3)2-4的优化构型均为由不同子体系的叠氮基α−N和B原子相连形成的环状结构。三聚体的船扭式构象比椅式构象的结合能低10.54 kJ•mol-1;四个新获得的四聚体的结合能差异较大,大小为3.1~45.65 kJ•mol-1。由焓变可知,单体形成二聚体在热力学上是不利的,而形成三聚体和四聚体在高达1200 K的温度下是有利的,同时分析比较了后续反应的热力学参数。