A New Synthetic Method for N-Mono- and N,N-Disubstituted Selenoamides

N-Mono and N,N-disubstituted selenoamides are synthesized in a one-pot procedure from nitriles, selenium metal and NaBH₄ followed by the amine group exchange of the intermediate primary selenoamide with an amine.     

Brans-Dick宇宙中的轻子数生成

讨论了\,Brans-Dicke\,理论中的辅助性标量,\phi,在宇宙的重子数不对称起源中所扮演的可能角色.在,Morganstern,关于,Brans-Dicke(BD)宇宙学的一系列工作的基础上, 讨论了这个引力性标量场的导数和重子流, J^μB ,或者重子--轻子'流, J^μB-L ,的耦合效应. 发现由这个耦合形成的自发重子数生成机制, 只要其中大统一发生的时标足够提前, 就可以产生足够的重子数不对称,n_B/s～10^-10. 此外,也研究了由,Davoudiasl,引进的里奇标量,R,的导数和重子流之间的相互作用耦合在辐射为主的,BD,宇宙中的重子数生成效应. 结果表明, 在此情况下因为,R,不再为零也同样可以获得重子数的不对称, 从而不同于爱因斯坦宇宙框架下的相关结论.     

一类代理多重签名方案的密码学分析与改进

2001年，傅晓彤等提出了一种新的代理多重签名体制，即多个原始签名人分别将签名权力委托给各自的代理签名人，再由这些代理签名人联合生成代表所有原始签名人的数字签名．然而，周红生等（2004）指出他们的方案不存在抗抵赖性以及代理签名者能滥用代理签名权的缺陷，同时给出了一个改进方案．本文指出，周红生等的方案也是不安全的，任一原始签名人或任一代理人都能生成有效的代理多重签名，而且可以任意修改代理签名的期限．为克服他们的安全性弱点，给出了一个改进的方案．     

Effect of temperature on the hybrid supercapacitor based on NiO and activated carbon with alkaline polymer gel electrolyte

A hybrid supercapacitor was fabricated with NiO and activated carbon as positive and negative electrode, PVA–KOH–H₂O containing 5 M KOH as alkaline polymer gel electrolyte, respectively. Cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge–discharge measurements were applied to investigate the dependence of the hybrid supercapacitor on the temperatures from − 20 to 40 °C. The results demonstrated that the capacitive performance of the hybrid supercapacitor turned even better with the temperatures rising up from − 20 to 40 °C. The increase of temperature improved the conductivity of the alkaline polymer gel electrolyte, decreased the charge-transfer resistance and made the better contact at the interface between the electroactive materials and the alkaline gel electrolyte at higher operating temperature. The maximum of the specific capacitance and energy density of the hybrid supercapacitor were 73.4 F/g and 26.1 Wh/kg at the current density of 0.1 A/g and the operating temperature of 40 °C, respectively.     

乘子交换子的有界性

本文研究了乘子与Lipschitz函数生成的交换子,建立了这类交换子在Lebesgue空间与Hardy空间中的有界性．     

Inequalities of Maximum of Partial Sums and Weak Convergence for a Class of Weak Dependent Random Variables

In this paper, we establish a Rosenthal-type inequality of the maximum of partial sums for ρ^- -mixing random fields. As its applications we get the Hájeck -Rènyi inequality and weak convergence of sums of ρ^- -mixing sequence. These results extend related results for NA sequence and p^＊ -mixing random fields,     

Comparison of two approximate methods for hard-edged diffracted flat-topped light beams

The integral resulted in an infinite series of Bessel functions and expanding a hard aperture into a complex-Gaussians shape are proposed as two methods for studying the propagation properties of the hard-edged diffraction flat-topped light beam. Using the two methods, the corresponding analytical propagation equations of flat-topped light beams through a circular apertured ABCD optical system are obtained. Some numerical calculations and comparative analyses by using the two methods and the diffraction integral formulae are made. It is shown that the first method of an infinite series of Bessel functions is superior to the second of expanding a hard aperture function into a complex-Gaussians shape at the aspect of calculation accuracy, but the second method is superior to the first method at the aspect of the improvement in the calculation efficiency.     

集值映射空间在紧开拓扑下的$\aleph_0$性质

本文讨论了点紧致的连续集值映射空间在赋予紧开拓扑下的某些拓扑性质,证明了:若$X,Y$为$\aleph_0$空间,则$X$到$Y$上的点紧致的连续集值映射族依紧开拓扑是$\aleph_{0}$空间,从而将Michael$^{[1]}$的结论推广到更大的映射空间类上.     

纳米级掺锶钴氧化物的溶胶-水热合成及其表征

采用硝酸钴、硝酸锶及尿素为原料,通过溶胶-水热合成方法制备出掺锶钴氧化物前驱体.前驱体在氮气保护下以650 ℃恒温煅烧3 h,获得纳米级粉末状黑色氧化物.利用DSC-TG、XRD、SEM、PPMS、FT-IR等对产品的物性和结构进行了表征.结果表明:Sr2+进入钴氧化物晶格,最终获得纳米级的掺锶钴氧化物,产物具有顺磁性.     

The Aharonov–Bohm effect in noncommutative quantum mechanics

The Aharonov–Bohm effect in noncommutative (NC) quantum mechanics is studied. First, by introducing a shift for the magnetic vector potential we give the Schrödinger equations in the presence of a magnetic field on NC space and NC phase space, respectively. Then, by solving the Schrödinger equations, we obtain the Aharonov–Bohm phase on NC space and NC phase space, respectively.