ZnSe/ZnSxSe1−x heterojunction valence band discontinuity measured by x-ray photoelectron spectroscopy

X-ray photoelectron spectroscopy was used to measure the valence band discontinuity at the ZnSe/ZnS_xSe_1−x interface as a function of alloy composition. Due to the large lattice mismatch, the experimental values have to be corrected in order to account for strain in the ZnSe layers. We find the valence band discontinuity to vary between 0 and 0.76 eV as a function of S content x. This result is in excellent agreement with theoretical calculations. It also shows that the conduction band discontinuity is not negligibly small.     

Comparison of the NIST and BIPM Standards for Air Kerma in Medium-Energy X-Rays

A comparison has been made of the air-kerma standards for medium-energy x-rays of the National Institute of Standards and Technology (NIST) and the Bureau International des Poids et Mesures (BIPM). The comparison involved a series of measurements at the BIPM and the NIST using the air-kerma standards and three NIST reference-class transfer ionization chamber standards. Reference beam qualities in the range from 100 kV to 250 kV were used. The results show the standards to be in reasonable agreement within the combined standard uncertainty of the comparison of 0.37 %, although a significant trend with radiation quality is observed and the possible sources discussed.     

X射线全息术及分辨率

本文论述了限制Ｘ射线全息术分辨率的一些主要因素．在记录过程中，影响Ｘ射线全息术分辨率的主要因素是样品对Ｘ射线的衍射和相干散射、记录方式和Ｘ射线束的相干性．本文分别讨论了上述各因素和Ｘ射线全息术分辨率的关系，指出了Ｘ射线全息术和一般光学全息术的差别．在再现过程中，影响Ｘ射线全息术分辨率的因素主要有两个，一个是探测工具的分辨率低于Ｘ射线全息图干涉条纹的空间频率，另一个是像差．本文着重讨论了在探测工具的分辨率高于Ｘ射线全息图干涉条纹空间频率的条件下像差和Ｘ射线全息图分辨率的关系，以及如何消除像差等间题．     

Properties and structures of Co-based metallic glasses

A fundamental study on Co-based metallic glasses has been conducted. The study focused on understanding the changes of the properties and structures of an Fe-B-Si glass as a function of Co, Co-Ni, Co-Mn, and Co-Ni-Mo additions. The separate addition of Co, Co-Ni, Co-Mn, and Co-Ni-Mo elements was successful in such a way that four new metallic glasses were produced. The compositions of the new glasses are Fe₆₆Co₁₈B₁₅Si₁, Co₆₆Fe₄B₁₄Si₁₅, Co₇₆Fe₂Mn₄B₁₂Si₆, and Co₆₉Fe₄Mo₂B₁₂Si₁₂. Consequently, an evaluation of the physical and magnetic properties was determined. Furthermore, the internal and surface structures of the glasses have been characterized by a transmission electron microscope (TEM), and a scanning tunneling microscope (STM), respectively. A comparison between the internal and surface structures of the glasses was carried out on both amorphous and crystalline forms. As a result, a correlation between the properties and structures of the glasses is established.     

Mechanical and tribological properties of TiN and SiCN nanocomposite coatings deposited using methyltrichlorosilane

The paper examines nanocomposite coatings based on TiN and SiCN obtained by plasma-enhanced chemical vapor deposition (PECVD) using methyltrichlorosilane (MTCS) as one of the precursors. The nanocomposite coatings demonstrate four types of structures depending on deposition modes: nc-TiN, nc-TiN/a-SiCN, nc-TiNC/nc-TiSi₂/a-SiCN, and nc-TiNC/nc-TiCl₂/a-SiCN. The nanohardness and elastic modulus of the coatings reach 31 and 350 GPa, respectively. The coatings on substrates of hard alloys, high-speed steel, and silicon increase the nanohardness of the base from 10 to 100%. The correlation between the H/E ratio and wear resistance is not observed. The coatings deposited at low radiofrequency powers demonstrate good adhesion to silicon substrates. It is shown that the use of MTCS as the main precursor allows one to obtain hard and wear-resistant nanocomposite coatings. __________ Translated from Poroshkovaya Metallurgiya, Vol. 47, No. 1–2 (459), pp. 125–133, 2008.     

氧化铝缓冲层对ZnO薄膜性质的影响

采用反应磁控溅射的方法在石英衬底上制备了一层AI2O3薄膜,并将其作为后续ZnO薄膜生长的缓冲层.然后,采用反应磁控溅射的方法在AI2O3缓冲层上制备了ZnO薄膜.对比研究了引入Al2O3缓冲层前后,ZnO薄膜的结构和光学特性.通过引入Al2O3缓冲层,发现ZnO薄膜样品的(002)方向X射线衍射峰的半峰宽(FWHM)明显减小,光致发光谱中与缺陷相关的可见发光峰强度明显减弱,吸收光谱中的吸收边变得更加陡峭.这些结果表明引入Al2Q3缓冲层后,ZnO薄膜的结构和光学特性得到了很大改善,为制备高质量ZnO薄膜提供了参考.     

基于Modelica技术的Dante谱仪解谱建模仿真

针对ICF实验数据量大、多学科、多项目的特点,提出了采用Modelica多领域建模与仿真语言进行ICF实验数据处理的建模思路,以使模型的标准统一,可读性强,同时利于ICF实验的知识积累,并进行了软X光谱仪基函数解谱方法的Modelica建模仿真。仿真结果符合实际情况,对构建基于Modelica的ICF实验数据处理系统具有重要意义。     

Crystallization of Enantiomerically Pure Proteins from Quasi‐Racemic Mixtures: Structure Determination by X‐Ray Diffraction of Isotope‐Labeled Ester Insulin and Human Insulin

As a part of a program aimed towards the study of the dynamics of human insulin‐protein dimer formation using two‐dimensional infrared spectroscopy, we used total chemical synthesis to prepare stable isotope labeled [(1‐¹³C=¹⁸O)Phe^B24)] human insulin, via [(1‐¹³C=¹⁸O)Phe^B24)] ester insulin as a key intermediate product that facilitates folding of the synthetic protein molecule (see preceding article). Here, we describe the crystal structure of the synthetic isotope‐labeled ester insulin intermediate and the product synthetic human insulin. Additionally, we present our observations on hexamer formation with these two proteins in the absence of phenol derivatives and/or Zn metal ions. We also describe and discuss the fractional crystallization of quasi‐racemic protein mixtures containing each of these two synthetic proteins.     

Morphology and Thermal Properties of Poly[bis(β-phenoxyethoxy)phosphazene]

The structure and thermal properties of poly[bis(-phenoxyethoxy)phosphazene)] (PBPEP) newly synthesized by us were investigated. The crystallization from the melt, the volumetric relaxation in the amorphous phase in the upper vicinity of the glass transition temperature (T _g) and the enthalpy of relaxation of the glass in the lower vicinity of the T _g were shown to be very slow. These slow rates may be related to the low chain mobility due to the bulky side chain. Two kinds of crystal forms, called and forms were found in the melt-crystallized sample. These forms were clearly seen as individual types of spherulites by optical microscopy. The melting temperature of these crystals were analyzed by the Hoffmann–Weeks plot. The so-called T(1) transition that had often been detected in many crystalline polyphosphazenes as the transition from the crystal phase to the mesophase was not observed by x-ray diffraction at elevated temperatures.     

Crystallization studies of crystalline–amorphous blends: Polyethylene terephthalate (PET)–polystyrene (PS)

Crystallization of crystalline–amorphous blends of polyethylene terephthalate–polystyrene (PET–PS) with and without the addition of triphenyl phosphate was followed by differential scanning calorimetry. Triphenyl phosphate acts as a nucleating agent. Thermal studies of various PET–PS compositions, crystallized from melt, have shown a marginal decrease in the rate of crystallization and an increase in the percentage of crystallinity of the blends. Triphenyl phosphate was found to have a nucleation-facilitation effect on 1:1 PET–PS blend composition and also has improved the crystallinity of PET in quenched blends.