PMA‐b‐PAA‐controlled synthesis of one‐dimensional CaCO3 superstructures

Crystallization of calcium carbonate (CaCO₃) crystals by a gas‐liquid diffusion method has been carried out in aqueous solution using a double‐hydrophilic block copolymer (DHBC) poly(maleic anhydride)‐b‐poly(acrylic acid) (PMA‐b‐PAA). The as‐prepared products were characterized with X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), selected area electron diffraction (SAED), high‐resolution transmission electron microscopy (HRTEM) and infrared spectroscopic analysis (FT‐IR). Uniform one‐dimensional calcite micro/nanostructures with different morphologies are fabricated through an assembled process. The influence of PMA‐b‐PAA copolymer concentration on the morphology of calcite nano/microwires is investigated, which plays an important role in the morphological control of building blocks composed of one‐dimensional calcite crystals. The possible formation mechanism of one‐dimensional CaCO₃ crystals was discussed. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Some properties on far-field pattern of scattering by penetrable obstacle in ocean waveguide

This paper is concerned with the properties of propagation fax-field patterns corresponding to the scattering of time harmonic acoustic waves by a bounded penetrable obstacle in an ocean waveguide. The sets of solutions to the transmission problem are constructed such that the restriction of these solutions to the boundary of the penetrable obstacle is dense in a Hilbert space. Then conditions under which a set of propagation far-field patterns is complete in a Hilbert space are determined. These properties are important in investigating inverse transmission problems in an ocean waveguide.     

关于Baskakov-Durrmeyer算子的局部逼近

本文主要讨论了用Ｈｏｌｄｅｒ连续函数表示Ｂａｓｋａｋｏｖ－Ｄｕｒｒｍｅｙｅｒ算子局部逼近阶的特征刻划问题。     

给定主曲率函数的一类特殊曲面的位置向量场

本文给出了 Ｒ３,Ｒ２．１内给定主曲率函数的一类特殊曲面在定义域范围内的位置向量场,从而完满地解决了［１］中所讨论的问题．     

Maximal regular subsemigroups of certain semigroups of transformations

Let T _n and P _n be the full and partial transformation semigroups on a finite set of order n respectively. The properties of the subsemigroups of T _n and P _n have been widely studied. But the maximal regular subsemigroups of T _n and P _n seem to be unknown. In this note, we determine all the maximal regular subsemigroups of all ideals of T _n and P _n . April 7, 1999     

组氨酸、谷胱甘肽混合修饰金纳米团簇的光稳定性研究

金纳米团簇(简称金簇)由几到几百个金原子及修饰试剂组成,由于其尺寸接近于电子费米波长,表现出良好的发光特性及生物相容性,是一类新型纳米标记探针。目前,金纳米团簇在生物检测、细胞成像、癌症诊断及治疗等领域受到研究者的广泛关注。然而,对于光照条件下金簇的稳定性还不清楚。在合成组氨酸、谷胱甘肽混合修饰金簇的基础上,系统研究了光照条件下金簇在不同pH(5.0,7.4和9.0)的荧光变化规律,结果表明,在氙灯强光照射下,金纳米团簇的荧光会随着照射时间的增加逐渐降低,在pH 9.0条件下比pH 5.0及7.4时降低更快,说明金簇在pH 5.0及7.4时光稳定性更好。在此基础上,采用紫外-可见吸收光谱、红外光谱等手段研究了光照前后金簇表面基团的变化规律,发现光照后金簇的紫外可见吸收光谱及红外光谱均发生了明显的变化,说明光照导致金簇表面修饰基团发生了变化。当向体系中通入氮气后,金簇最大发射波长处荧光强度随照射时间的变化明显变慢,说明金簇表面基团与溶液中溶解氧发生了反应,导致金簇表面电荷及修饰试剂状态发生变化,从而导致金簇荧光产生猝灭。相关研究结果对于金纳米团簇在生命科学及分析化学等领域的进一步应用具有一定的参考价值。     

高温超导YBCO双晶结毫米波谐波混频的实验研究

我们采用氧化锆双晶衬底制备了ＹＢａＣｕＯ双晶结,测量了其电流电压特性,采用液氮制冷和小型脉冲管制冷机分别实现了毫米波谐波混频实验．通过实验结果的初步讨论和比较,我们对系统的微波耦合和噪声抑制提出了改进方案     

A quasi-discrete Hankel transform for nonlinear beam propagation

We propose and implement a quasi-discrete Hankel transform algorithm based on Dini series expansion (DQDHT) in this paper. By making use of the property that the zero-order Bessel function derivative J' ₀(0)=0, the DQDHT can be used to calculate the values on the symmetry axis directly. In addition, except for the truncated treatment of the input function, no other approximation is made, thus the DQDHT satisfies the discrete Parseval theorem for energy conservation, implying that it has a high numerical accuracy. Further, we have performed several numerical tests. The test results show that the DQDHT has a very high numerical accuracy and keeps energy conservation even after thousands of times of repeating the transform either in a spatial domain or in a frequency domain. Finally, as an example, we have applied the DQDHT to the nonlinear propagation of a Gaussian beam through a Kerr medium system with cylindrical symmetry. The calculated results are found to be in excellent agreement with those based on the conventional 2D-FFT algorithm, while the simulation based on the proposed DQDHT takes much less computing time.     

远场光电探测器系统受激光干扰与损伤效果估计

空间光电探测器与地面距离较远 ,用脉冲或连续式激光直接损伤远场探测器非常困难。但光电探测器的光学接收系统对激光照射而言具有巨大的光学天线增益 ,实现激光对光电探测器的干扰与损伤是有可能的。通过计算 ,比较了脉冲激光与连续激光对远场光电探测器的作用效果 ,并在实验中验证了激光轴外干扰光电探测器系统的可行性     

Anomalous microwave reflection from a metal surface induced by spoof surface plasmon

The reflection of X-band microwaves (8-12 GHz) from a metallic aluminum (Al) surface with groove grating corrugations was investigated experimentally. It was shown that the reflection of p-polarization is much less than the microwave reflected from the corresponding area of an unruled Al surface, with selective wavelength. The experimental results demonstrated that the anomalous microwave reflection is strongly associated with the excitation of spoof surface plasmons at the Al-air interface by the surface grating coupler. This near-total absence of reflected microwaves is similar to the famous Wood's anomaly in the optical regime and is of fundamental importance to the applications of spoof surface plasmons in the microwave regime.