整函数及其差分分担有限集的唯一性

研究了整函数及其差分多项式分担有限复数集的唯一性,得到了如下结果:设S_m={1,ω,…,ω~(m-1)},其中ω=cos(2π/m)+i sin(2π/m),c为非零有限复数,n(>5),m(≥2)均为正整数.如果f(z),g(z)为有限级整函数,满足E(S_m,f(z)~n(f(z)-1)f(z+c))=E(S_m,g(z)~n(g(z)-1))g(z+c)),那么f(z)≡g(z).     

亚纯函数及其n阶导数权分担两个值

研究亚纯函数及其n阶导数权分担两个值的唯一性问题.得到了：如果两个非常数亚纯函数f,g分担（∞,∞）,f（n）与g（n）分担（1,0）,n（≥0）为一整数,且满足C0：=（4n＋6）λ＋δn＋1（0,f）＋δn＋1（0,g）＋δn＋2（0,f）＋δn＋2（0,g）＋δn（0,f）〉4n＋10,其中λ=max{min{Θ（∞,f）,Θ（0,f）},min{Θ（∞,g）,Θ（0,g）}},那么f（n）·g（n）≡1,或者f≡g.该结果改进了前人的有关定理.     

基于方向数据的核密度估计的对称检验的大偏差

设$f_n$是基于核函数$K$和取值于$d$-维单位球面${\mathbb{S}}^{d-1}$的独立同分布随机变量列的非参数核密度估计. 我们证明了若核函数是有界变差函数, 随机变量的密度函数$f$是连续的和对称的, $\{\sup_{x\in {\mathbb{SS}}^{d-1}}|f_n(x)-f_n(-x)|,n\ge 1\}$的大偏差原理成立.     

Enantiomerization Mechanism of Thalidomide and the Role of Water and Hydroxide Ions

The significance of the molecular chirality of drugs has been widely recognized due to the thalidomide tragedy. Most of the new drugs reaching the market today are single enantiomers, rather than racemic mixtures. However, many optically pure drugs, including thalidomide, undergo enantiomerization in vivo, thus negating the single enantiomers’ benefits or inducing unexpected effects. A detailed atomic level understanding of chiral conversion, which is still largely lacking, is thus critical for drug development. Herein, we use first‐principle density function theory (DFT) to explore the mechanism of enantiomerization of thalidomide. We have identified the two most plausible interconversion pathways for isolated thalidomide: 1) proton transfer from the chiral carbon center to an adjacent carbonyl oxygen atom, followed by isomerization and rotation of the glutarimide ring (before the proton hops back to the chiral carbon atom); and 2) a pathway that is the same as “1”, but with the isomerization of the glutarimide ring occurring ahead of the initial proton transfer reaction. There are two remarkable energy barriers, 73.29 and 23.59 kcal mol^?1, corresponding to the proton transfer and the rotation of the glutarimide ring, respectively. Furthermore, we found that water effectively catalyzes the interconversion by facilitating the proton transfer with the highest energy barrier falling to approximately 30 kcal mol^?1, which, to our knowledge, is the first time that this important role of water in chiral conversion has been demonstrated. Finally, we show that the hydroxide ion can further lower the enantiomerization energy barrier to approximately 24 kcal mol^?1 by facilitating proton abstraction, which agrees well with recent experimental data under basic conditions. Our current findings highlight the importance of water and hydroxide ions in the enantiomerization of thalidomide and also provide new insights into the mechanism of enantiomerization at an atomic level.     

Preparation and characterization of N–Ti-MCM-22 mesoporous molecular sieve and investigation of its photocatalytic properties

Nanocrystalline N-doped and Ti-containing MCM-22 catalyst was synthesized by the static hydrothermal method, using sodium azide as nitrogen source for doping, and tetra-n-butyl titanate [Ti(OC₄H₉)₄] as precursor for TiO₂. The catalysts were characterized by X-ray diffraction, transmission electron microscopy, and energy-dispersive spectroscopy. The results showed that a mesoporous region with ca. 3-nm pore size was created by expansion between lamellar crystalline sheets in Ti-MCM-22. Nitrogen was substituted for some of the lattice oxygen atoms. During liquid phase photocatalytic degradation of methylene blue under high-pressure Hg arc lamp irradiation, the as-prepared N-doped Ti-MCM-22 exhibited much higher activity than the undoped Ti-MCM-22, attributed to the effect of the nitrogen dopant. The effects of N-doping amount, catalyst concentration, initial solution pH, and initial concentration of MB on the photocatalytic activity were investigated.     

In situ synthesis of Ag–Cu bimetallic nanoparticles in silicate glass by a two-step ion-exchange route

Ag–Cu bimetallic nanoparticle/silicate glass composites were fabricated by means of a two-step ion-exchange and subsequently thermal treatment. Optical absorption spectroscopy and transmission electron microscopy (TEM) were used to study the influence of preparation conditions on the formation of Ag–Cu bimetallic nanoparticles in silicate glass. The results show that the volume fraction of copper nanoparticles increases with ion-exchange duration when keeping the same annealing temperature and duration in hydrogen atmosphere during the first stage of Cu doped glass. The Cu doped glass is beneficial to the formation of Ag nanoparticles during subsequent Ag⁺ for Na⁺ ion exchange. Extending Cu⁺ for Na⁺ ion exchange duration makes against the introduction of Ag ions into the Cu doped glass and the formation of Ag nanoparticles in the glass matrix. A few Cu₂O nanoparticles were found in the glass matrix due to the oxidization of small Cu nanoparticles.     

The approximation of Laplace–Stieltjes transformations with finite order on the left half plane

In this paper, we study the error in approximating the analytic function defined by a Laplace–Stieltjes transformation of finite order, which converges on the left half plane, and obtain the relation theorems between the error, the coefficients, and the proximate order of the Laplace–Stieltjes transformation.     

Dirichlet级数及其Dirichlet-Hadamard 乘积的增长性

研究了一类Dirichlet级数关于q-级的增长性问题,并讨论了由两个Dirichlet级数组成的Dirichlet-Hadamard乘积的增长性,获得了Dirichlet-Hadamard乘积与原级数在增长性方面的几个关系.     

High performance two-color one megapixel CMOS ROIC for QWIP detectors

FLIR Systems, Inc. has designed and fabricated the ISC0501 CMOS readout integrated circuit (ROIC) for quantum well infrared photodetectors (QWIPs). The ISC0501 is a two-color 1024 × 1024 format array with a 30 μm pixel pitch. The ROIC contains a separate analog signal path for each wavelength band. Separate signal paths allow the two-colors to have optimized detector biases, integration times, offsets and gains. This architecture also allows both colors to simultaneously sample a scene and readout the pixel data. This paper will describe the interface, design and features of the ROIC as well as a summary of the characterization test results. A sample image is included from a focal plane array (FPA) built by the Jet Propulsion Laboratory (JPL) using the ISC0501 ROIC with QWIP detectors designed by JPL.     

单因素方差分析的一种非参数统计模型方法

本文研究了单因素方差分析中样本是连续的位置参数族的假设检验问题,利用秩统计量,获得了一种有效的假设检验方法,同时也用计算机算出了检验统计量的部分概率函数值.