低温等离子体对塑料表面处理——低温等离子体对高密度聚乙烯表面处理的ESR研究

本文研究了不同处理条件(处理功率、处理时间和处理压力)下等离子体气体(Ar、N₂、O₂和空气等)对高密度聚乙烯表面处理产生的自由基的ESR谱。我们观察到等离子体处理产生的自由基是相当稳定的,它的ESR信号强度随处理功率和处理时间增加而增加。但处理压力对它影响不大。我们证明了紫外线对高密度聚乙烯表面产生自由基作用随处理条件而变化。并初步解释了谱的超精细相互作用。     

Effect of plasma treatment on interface property of BCN/GaN structure

Interface properties of BCN/GaN metal-insulator-semiconductor (MIS) structures are investigated by X-ray photoelectron spectroscopy (XPS) and capacitance versus voltage (C-V) characteristics measurements. The BCN/GaN samples are fabricated by in situ process consisting of plasma treatment and deposition of BCN film in the plasma-assisted chemical vapor deposition (PACVD) apparatus. XPS measurement shows that the oxide formation at the BCN/GaN interface is suppressed by nitrogen (N₂) and hydrogen (H₂) plasma treatment. The interface state density is estimated from C-V characteristics measured at 1 MHz using Terman method. The minimum interface state density appears from 0.2 to 0.7 eV below the conduction band edge of GaN. The minimum value of the interface state density is estimated to be 3.0 × 10¹⁰ eV⁻¹ cm⁻² for the BCN/GaN structure with mixed N₂ and H₂ plasma treatment for 25 min. Even after annealing at 430 °C for 10 min, the interface state density as low as 6.0 × 10¹⁰ eV⁻¹ cm⁻² is maintained.     

Intrinsic Fluorescence of Actin

In this work actin is used to illustrate connection of protein fluorescence characteristics with its structure. On one hand, it has been demonstrated what kind of information about the contribution of each tryptophan residues to the bulk fluorescence spectrum can be obtained from the special analysis of protein three-dimensional structure. On the other hand, potentials of intrinsic fluorescence for elucidation of proteins structure, dynamics and processes of folding-unfolding are shown. In particular, using this method a new essentially unfolded kinetic intermediate state of actin was detected and characterized, and the place of inactivated actin and its kinetic predecessor in the process of folding-unfolding was determined. It has been revealed that inactivated actin is not intermediate state between the native and completely unfolded states, as it has been accepted before, but a result of protein misfolding. On the basis of the obtained data a new model of actin folding-unfolding pathway has been proposed.     

HT—6M闭环反馈平衡控制系统

本文描述HT-6M托卡马克装置闭环反馈平衡控制系统的结构组成,通过对各个环节的简化,得到了有效实用的数学模型,进而分析了系统稳态和动态性能。实验结果表明,该系统运行可靠;并且,将等离子体环水平位移控制在2mm以内。     

On the hydrogen etching mechanism in plasma nitriding of metals

Iron alloys and aluminum were nitrogen implanted in a controlled oxygen atmosphere and the role of hydrogen on the surface etching mechanisms studied. The surface composition was analyzed by in situ photoemission electron spectroscopy (XPS). In iron alloys, hydrogen strongly etches oxygen, improving nitrogen retention on the surface. On the other hand, hydrogen removes nitrogen from aluminum surfaces, with a deleterious effect on the nitriding effectiveness. The oxygen removal in iron alloys is associated with the catalytic effect of electrons in d-orbitals and the nitrogen removal in aluminum is associated with a steric effect.     

“阳”加速器钼丝X-pinch初步实验研究

 在“阳”加速器上进行了直径分别为10, 15, 20 μm, 交叉角为32°,45°,60°的钼（Mo）丝X-pinch实验。“阳”加速器产生的电流峰值约520 kA，上升时间80 ns。实验中通过X射线功率谱仪和纳秒分幅相机等仪器对Mo丝X-pinch辐射特性进行了诊断。实验表明：Mo丝X-pinch过程中会出现多次X射线爆发，箍缩过程中产生的热点辐射出能量超过3 keV的X射线，探测到的最小热点直径小于30 μm。     

Electrophoretic study of the effect of ultradisperse iron powder on cotton seed proteins

The protein composition of seeds treated with a suspension of ultradisperse iron was studied using electrophoresis on PAAG. Changes were noted in the fractions with relative electrophoretic mobility (REM) 0.11 of water-soluble and REM 0.37 of buffer-soluble An-9 cotton seed proteins. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 384–385, July–August, 2006.     

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用高密度等离子体模型可以计算出一整套输运参数,并且在很宽的等离子体温度和密度范围内有合理的精度,可广泛应用于Z箍缩等离子体、激光聚变和磁约束聚变等领域,并将这个模型计算出的各种输运参数拟合成了实用的公式。     

Interpretive approach to collective effects of electrons in multicenter problems

Interpretive theoretical tools prove valuable in guiding the analysis of experiments in the realm of atomic clusters. Here, we review basic elements of an analytic approach that makes it possible to find and visualize the effective electrostatic potential and Coulomb correlations in multicenter problems. To illustrate the utility of these concepts we apply them to exploring molecular-doped metallic clusters. This study is aiming at a systematic, visual assessment of changes induced in screening, Coulomb correlation and effective potential by varying the charge of the electronegative impurity and its position in the cluster cage.     

Scanning probe microscopy characterization of gold-chemisorbed poplar plastocyanin mutants

Two poplar plastocyanin mutants adsorbed onto gold electrodes have been characterized at single molecule level by scanning probe microscopy. Immobilization of the two redox metalloprotein mutants on Au(1 1 1) surface was achieved by either a disulphide bridge (PCSS) or a single thiol (PCSH), both the anchoring groups having been introduced by site-directed mutagenesis. Scanning tunneling microscopy (STM) and atomic force microscopy (AFM) analysis gives evidence of a stable and robust binding of both mutants to gold. The lateral dimensions, as estimated by STM, and the height above the gold substrate, as evaluated by AFM, of the two mutants well agree with crystallographic sizes. A narrower height distribution is observed for PCSS compared to PCSH, corresponding to a more homogeneous orientation of the former mutant adsorbed onto gold. Major differences between the mutants are observed by electrochemical STM. In particular, the image contrast of adsorbed PCSS is affected by tuning the external electrochemical potential to the redox levels of the mutant, consistent with some involvement of copper active site in the tunneling process. On the contrary, no contrast variation is observed in electrochemical STM of adsorbed PCSH. Moreover, scanning tunneling spectroscopy experiments reveal asymmetric I–V characteristics for single PCSS proteins, reminiscent of a rectifying-like behaviour, whereas an almost symmetric I–V relation is observed for PCSH.