Adsorption of L-Alanine on Cu（111） Studied by Scanning Tunnelling Microscopy

The adsorption of L-alanine on Cu（111） surface is studied by means of scanning tunnelling microscopy under ultra-high vacuum conditions. The results show that the adsorbates are chemisorbed on the surface, and can form a two-dimensional gas phase, chain phase and solid phase, depending on deposition rate and amount. The adsorbed molecules can be imaged as individual protrusions and parallel chains in gas and chain phases respectively. It is also found that alanine can form （2 × 2） superstructure on Cu（111） and copper step facet to （110） directions in solid phase. On the basis of our scanning tunnelling microscopic images, a model is proposed for the Cu（111）（2 ×2）-alanine superstructure. In the model, we point out the close link between （110）-direction hydrogen bond chains with the same direction copper step faceting.     

用吐温80-硫酸铵-水体系的液-固萃取光度法测定痕量镍

研究了Ni()-PAR在吐温80-硫酸铵-水体系中的最佳萃取条件,建立了水样中测定痕量镍的非有机溶剂液-固萃取光度法。在NH3·H2O-NH4Cl缓冲溶液中,金属配合物Ni()-PAR可被吐温80固相富集萃取,最大吸收波长为500nm,镍含量在0—1.0μg/mL范围内服从朗伯-比耳定律,表观摩尔吸光系数为6.345×104L·mol-1·cm-1。该法测定水样中镍含量,回收率可达96.3%—103.0%。     

The dynamical properties of Rydberg hydrogen atom near a metal surface

The dynamical properties of Rydberg hydrogen atom near a metal surface are presented by using the methods of phase space analysis and closed orbit theory. Transforming the coordinates of the Hamiltonian, we find that the phase space of the system is divided into vibrational and rotational region. Both the Poincaré surface of section and the closed orbit theory verify the same conclusion clearly. In this paper we choose the atomic principal quantum number asn=20. The dynamical character of the exited hydrogen atom depends sensitively on the atom-surface distanced. Whend is sufficiently large, the atom-surface potential can be expressed by the traditional van der Waals force and the system is integrable. Whend becomes smaller, there exists a critical valued _c. Ford>d _c, the system is near-integrable and the motion is regular. While chaotic motion appears ford<d _c, and the system tends to be non-integrable. The trajectories become unstable and the electron might be captured onto the metal surface.     

Periodic solution and chaotic strange attractor for shunting inhibitory cellular neural networks with impulses

By using the continuation theorem of coincidence degree theory and constructing suitable Lyapunov functions, we study the existence, uniqueness, and global exponential stability of periodic solution for shunting inhibitory cellular neural networks with impulses, dx(ij)dt=-a(ij)x(ij)- summation operator(C(kl)inN(r)(i,j))C(ij) (kl)f(ij)[x(kl)(t)]x(ij)+L(ij)(t), t>0,t not equal t(k); Deltax(ij)(t(k))=x(ij)(t(k) (+))-x(ij)(t(k) (-))=I(k)[x(ij)(t(k))], k=1,2,...] . Furthermore, the numerical simulation shows that our system can occur in many forms of complexities, including periodic oscillation and chaotic strange attractor. To the best of our knowledge, these results have been obtained for the first time. Some researchers have introduced impulses into their models, but analogous results have never been found.     

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利用Matlab语言将EFIT程序反演计算过程进行优化整合,简化了程序操作步骤,并增加了对计算结果的分析与存储功能。利用整合后的 EFIT 程序,计算分析了 J-TXET 装置放电过程中等离子体磁场位形和其它参数的演变,绘制了等离子体压强剖面图、等离子体电流密度和安全因子分布等磁面信息的重建结果。此外,还将反演结果与软X射线测算数据进行比对。结果表明,改善后的EFIT程序能够初步满足对实验放电的反演计算分析要求,为J-TXET装置的放电控制和运行提供重要的参考数据。     

Post collision interactions and polarization effect in (e, 2e) collisions of helium

A modified distorted-wave Born approximation (DWBA) method is used to calculate the triple differential cross sections (TDCSs) in a coplanar asymmetric geometry for the electron impact single ionization of a He (1s²) atom at intermediate and lower energies. The post-collision interaction and the polarization effect in (e, 2e) collisions of helium are considered in the calculations. The polarization potentials from the damping method and density functional theory (DFT) are compared. Theoretical results are compared with the recent experimental data.     

RF and field measurements of the SSC-LINAC RFQ

The 53.667 MHz continuous-wave heavy ion RFQ has been designed and manufactured for the SSC-LINAC project.This four-rod RFQ accelerates ions with maximum mass to charge ratio of 7 from 3.728 keV/u to 143 keV/u.Measurements have been carried out to check the RF performance of the cavity and the quality of the electric field.The S11 of the power coupler is adjusted to better than-44 dB,and the Q0 of the cavity is 6440.The quality of the electric field is evaluated by the perturbation method.The measurement procedure and data analysis will be discussed in detail.The error due to gravity of the perturbation bead has been corrected by averaging the fields in different quadrants.As a result,the unflatness of the electric field is±2.5%,and the dipole field component distributes from 0%to 20%in different longitudinal positions,which indicates the asymmetry of the quadrupole field.The unflatness of the quadrupole field distribution represents a good agreement with the simulation results.High power RF test and beam commissioning of the RFQ are on schedule in early 2014.     

自旋场效应晶体管的原理和研究进展

基于电子具有自旋的特性,介绍了自旋场效应晶体管的基本原理和研究进展;通过研究发现自旋场效应晶体管具有良好的电导开关效应,外加磁场后则呈现出磁开关效应．     

Study of top and bottom contact resistance in one organic field-effect transistor

This paper reports that the organic field-effect transistors with hybrid contact geometry were fabricated, in which the top electrodes and the bottom electrodes were combined in parallel resistances within one transistor. With the facility of the novel structure, the difference of contact resistance between the top contact geometry and the bottom contact geometry was studied. The hybrid contact devices showed similar characteristics with the top contact configuration devices, which provide helpful evidence on the lower contact resistance of the top contact configuration device. The origin of the different contact resistance between the top contact device and the bottom contact device was discussed.     

R717双蒸发温度回路三级混流制冷系统的研究设计

基于降低初投资、节约能源、与环境友好及符合国情的原则,从制冷剂选用和制冷系统构成两个方面,探究"超低温"冷库制冷系统的设计方案和适用技术路线,完成了以天然工质氨为制冷剂,双蒸发温度回路三级混流制冷系统的可行性研究及其关键设备的开发设计,并以此建造了具有-30℃和-60℃库温,库容分别为30吨和200吨双冷间的"超低温"实验冷库。试运行半年,完全达到设计要求,已通过山东省科技厅专家组技术鉴定。