The dependence of the structural and optical properties on the Te mole fraction in ZnS1−xTex/GaAs heterostructures

Lattice-mismatched ZnS_1−xTe_x epilayers with various Te mole fractions on GaAs (100) substrates were grown by double well temperature gradient vapor deposition. X-ray diffraction patterns showed that the grown ZnS_1−xTe_x layers were epitaxial films. The photoluminescence spectra showed that the peak position of the acceptor-bound exciton (A⁰, X) varied dramatically with changing the Te mole fraction and that the behavior of the (A⁰, X) peak position of the ZnS_1−xTe_x epilayers with a small amount of the Te mole fraction was attributed to a bowing effect. The reflectivity and ellipsometry spectra showed that the absorption energy peak was significantly affected due to the Stoke's effect. These results provide important information on the structural and optical properties of ZnS_1−xTe_x/GaAs heterostructures for improving optoelectronic device efficiencies operating in the spectral range between near ultraviolet and visible regions.     

Estimation and Bootstrap with Censored Data in Fixed Design Nonparametric Regression

We study Beran's extension of the Kaplan-Meier estimator for thesituation of right censored observations at fixed covariate values. Thisestimator for the conditional distribution function at a given value of thecovariate involves smoothing with Gasser-Müller weights. We establishan almost sure asymptotic representation which provides a key tool forobtaining central limit results. To avoid complicated estimation ofasymptotic bias and variance parameters, we propose a resampling methodwhich takes the covariate information into account. An asymptoticrepresentation for the bootstrapped estimator is proved and the strongconsistency of the bootstrap approximation to the conditional distributionfunction is obtained.     

便携式岩样核磁共振分析仪磁体的设计

核磁共振中的磁体设计有许多方案，但是要使磁体体积小、重量轻、均匀区大、稳定性好，将面临一系列的问题. 而这些问题的解决主要依赖于电磁场计算. 文中首先阐述这些问题，然后对方案进行优化分析计算，从中找出一个最佳的解决方案. 采用本方案研制出来磁体，我们研制成功了便携式核磁共振岩样分析仪. 经过多次的现场实验测试表明由该磁体构成的磁共振岩样分析仪的稳定性高、重复性好、满足现场恶劣的环境要求.     

Single-column ion chromatography of passive monitors for atmospheric pollution

Nitrite, nitrate and sulfate anions deposited on passive monitors were determined by using single-column ion chromatography. These monitors were exposed outdoors for various periods of time in an atmosphere with a very low degree of pollution, and they were used to evaluate the rate of deposition of some corrosive species on metallic materials. Two types of passive monitors were studied, namely sulfation and nitration plates. Comparison of the results obtained by using the classical turbidimetric method and single-column ion chromatography shows that turbidimetry is inappropriate for low sulfate concentrations (<2.5 mg/plate) deposited on sulfation plates. Thus, ion chromatography should be used to obtain a representative value of sulfate deposition because it allows the determination of sulfate in amounts as low as 200 μg/plate without further preconcentration. For nitration plates, ion chromatography permits simultaneous determination of nitrite, nitrate and sulfate from the same plate, whereas only nitrite can be determined by the classical colorimetric method. Both gluconate/borate and phthalate eluents were investigated and the results show that phthalate eluent is more appropriate for these plates. It was found that the pH of the sample has an important effect on the area of the sulfate peak. For both eluents, the area increases when the sample pH is lower than 6. This demonstrates the importance of an adequate sample treatment before injection in order to obtain reproducible and accurate values.     

Exact results and self-averaging properties for random-random walks on a one-dimensional infinite lattice

We present new exact results for a one-dimensional asymmetric disordered hopping model. The lattice is taken infinite from the start and we do not resort to the periodization scheme used by Derrida. An explicit resummation allows for the calculation of the velocityV and the diffusion constantD (which are found to coincide with those given by Derrida) and for demonstrating thatV is indeed a self-averaging quantity; the same property is established forD in the limiting case of a directed walk.     

Butson Hadamard matrices with partially cyclic core

In this paper, we introduce a class of generalized Hadamard matrices, called a Butson Hadamard matrix with partially cyclic core. Then a new construction method for Butson Hadamard matrices with partially cyclic core is proposed. The proposed matrices are constructed from the optimal balanced low-correlation zone(LCZ) sequence set which has correlation value ?1 within LCZ.     

马氏环境中的马氏链与马氏双链

本文研究了马氏环境中的马氏链,利用马氏双链的性质,得到了马氏环境中的马氏链回返于小柱集上的概率的若干估计式.     

Effect of FeCl3 and acetone on the structure of Na–montmorillonite studied by Mössbauer and XRD measurements

⁵⁷Fe Mössbauer spectroscopy, X-ray diffraction, X-ray fluorescence spectroscopy and infrared spectroscopy were used to study the effect of FeCl₃ and acetone on the structure of a Na–bentonite. XRD indicated the incorporation of Fe³⁺ ions into the interlayer space since the basal lattice spacing of montmorillonite increased to 1.6 from 1.24 nm after treatment with FeCl₃ dissolved in acetone. Interlayer Na⁺ ions could be exchanged to Fe³⁺. Magnetically split Mössbauer subspectra with internal magnetic fields 41 and 46 T at 74 K, were associated with two main Fe³⁺ microenvironments within the interlayer regions. The resultant Fe–montmorillonite was successfully applied as a catalyst in the preparation of 1,1-diacetates from aromatic aldehydes and acetic acid anhydride.     

Determination of piezoelectric coefficients of ferroelectric thin films using GaAs:Cr adaptive interferometer

We report on simple interferometric technique for the measurement of piezoelectric coefficients of thin films using GaAs:Cr adaptive photodetectors in the geometry of modified Mach–Zehnder interferometer. The technique needs no special vibroinsulation and automatically adjusts and keeps the operation point of the interferometer. Strong hysteresis effects with a slightly asymmetric form of the hysteresis loop were observed at the dependence of d₃₃ coefficients of the Pb(Zr,Ti)O₃ (PZT) thin film versus DC electric field. The obtained values of d₃₃ coefficients are in agreement with known data.     

Discovery of a small-molecule inhibitor of Dvl–CXXC5 interaction by computational approaches

The Wnt/β-catenin signaling pathway plays a significant role in the control of osteoblastogenesis and bone formation. CXXC finger protein 5 (CXXC5) has been recently identified as a negative feedback regulator of osteoblast differentiation through a specific interaction with Dishevelled (Dvl) protein. It was reported that targeting the Dvl–CXXC5 interaction could be a novel anabolic therapeutic target for osteoporosis. In this study, complex structure of Dvl PDZ domain and CXXC5 peptide was simulated with molecular dynamics (MD). Based on the structural analysis of binding modes of MD-simulated Dvl PDZ domain with CXXC5 peptide and crystal Dvl PDZ domain with synthetic peptide–ligands, we generated two different pharmacophore models and applied pharmacophore-based virtual screening to discover potent inhibitors of the Dvl–CXXC5 interaction for the anabolic therapy of osteoporosis. Analysis of 16 compounds selected by means of a virtual screening protocol yielded four compounds that effectively disrupted the Dvl–CXXC5 interaction in the fluorescence polarization assay. Potential compounds were validated by fluorescence spectroscopy and nuclear magnetic resonance. We successfully identified a highly potent inhibitor, BMD4722, which directly binds to the Dvl PDZ domain and disrupts the Dvl–CXXC5 interaction. Overall, CXXC5–Dvl PDZ domain complex based pharmacophore combined with various traditional and simple computational methods is a promising approach for the development of modulators targeting the Dvl–CXXC5 interaction, and the potent inhibitor BMD4722 could serve as a starting point to discover or design more potent and specific the Dvl–CXXC5 interaction disruptors.