D.c. conductivity of amorphous CulnSe2 films

Journal of Materials Science Letters -     

Pulsed NMR in solid D2. II. Stimulated echo

A study of the NMR stimulated echo resulting from an r.f. three-pulse sequence is presented for hcp D₂ with para-D₂ concentrations X between 0.06 and 0.49 and over the temperature range 0.07 < T < 1.5 K. The echo has two components, a sharp one on top of a broad one, which are the signals of the I = I (p-D₂) and the I= 2 (o-D₂) spins respectively. The echo widths reflect the different degrees of molecular orientational ordering. The echo amplitudes are studied as a function of the experimental parameters in the r.f. pulse sequence. The temperature dependence of the amplitude shows the expected Curie law behavior for the I = 2 spins, but a strong deviation from this law for the I = 1 spins. This anomalous behavior is consistent with that found for the I = 1 solid echo signal. The echo decay time _E is found to be very different for both spin systems, both in magnitude and in temperature dependence. The comparison of the I=1 spin results in D₂ with those in H₂, where the molecular orientational ordering is also from quadrupolar interaction, shows substantial differences. These are discussed in terms of the spin diffusion within each NMR line, and of the cross-relaxation between the two I = 1 and I = 2 spin systems.     

Interface Engineering in 2D/2D Heterogeneous Photocatalysts

Assembling different 2D nanomaterials into heterostructures with strong interfacial interactions presents a promising approach for novel artificial photocatalytic materials. Chemically implementing the 2D nanomaterials’ construction/stacking modes to regulate different interfaces can extend their functionalities and achieve good performance. Herein, based on different fundamental principles and photochemical processes, multiple construction modes (e.g., face-to-face, edge-to-face, interface-to-face, edge-to-edge) are overviewed systematically with emphasis on the relationships between their interfacial characteristics (e.g., point, linear, planar), synthetic strategies (e.g., in situ growth, ex situ assembly), and enhanced applications to achieve precise regulation. Meanwhile, recent efforts for enhancing photocatalytic performances of 2D/2D heterostructures are summarized from the critical factors of enhancing visible light absorption, accelerating charge transfer/separation, and introducing novel active sites. Notably, the crucial roles of surface defects, cocatalysts, and surface modification for photocatalytic performance optimization of 2D/2D heterostructures are also discussed based on the synergistic effect of optimization engineering and heterogeneous interfaces. Finally, perspectives and challenges are proposed to emphasize future opportunities for expanding 2D/2D heterostructures for photocatalysis.     

Pulsed NMR studies in solid D2. I. Solid echo

The solid echoes for both I = 1 and I = 2 nuclear spins from a two-pulse sequence are studied forp-D₂ concentrations between 0.06 and 0.5 and for 0.06 < T < 1.5 K. The drop of the I = 1 echo amplitude from Curie's law reported earlier is confirmed and is discussed. The density matrix method, previously developed to describe the I = 1 echo properties in solid H₂ as a function of various parameters, is applied to p-D₂, and similarly accounts for most of the observations. An analysis of the I =2 echoes for o-D₂ is carried out in similar fashion in the absence of a complete density matrix theory. Studies of the echo amplitude for the I = 1 and I = 2 spins versus r.f. pulse widths are reported and discussed. Various measurements associated with the echo decay as a function of the time between the two r.f. pulses are described. They include the I = 2 echo maximum shift respective to that of I = 1, the echo amplitude ratio S (I = 1)/S(I =2), the intermodular nuclear interaction magnitude, the local inhomogeneous field distribution, and the absence of expected satellite echoes for I =2. A comparison is made with the results of a similar study on solid H₂.     

I2D

I2D意为“从创新到设计”（Innovatlon To Design），反映了公司的理念：优秀设计是在概念上实现突破性创新、并把创新概念转化为独特卓越设计的战略性过程。     

基于工程三视图三维实体重构技术的研究

提出了一种利用ObjectARX技术进行三维重构的方法。通过对工程三视图中各种二维图形特征的分类和提取,进行二维视图特征的匹配,以投影模式库为基础求得与之对应的三维基本体素。然后按一定规则将这些基本体素通过各种布尔运算及坐标变换最终形成三维实体,最后在AutoCAD上开发了一个重建系统。在算法的具体实现过程中采用了新颖的二维特征识别方法及匹配方法,比较成功的完成了一定范围内的三维实体的重建。     

尼康D2Xs

最近,笔者试用了尼康最新上市的数码单反旗舰D2Xs,与2004年9月发布的D2X相比,只能说是其改进版,算不上更新换代,和尼康D70s、D2Hs等一样是同机型的健全与成熟,故尼康习惯地用其原机型后面加个小s命名.也正因为如此,D2Xs的"升级"并不令尼康影友们看好与兴奋.笔者经过一段时间试用,感觉D2Xs对于D2X的改进与完善还是必要的、成功的,可以说是经典的再提升,因为D2X问世后就成为广受赞誉的名机.这次的完善,对于尼康"影像·从心"理念的显现和一个素以专业、稳重的影像器材制造商来说,无可厚非,应该是一个理智的举措--不让经典留下遗憾.     

2D Josephson junction

The paper is devoted to the determination of processes in the two-dimensional Josephson junction via numerical solution of 2+1 dimensional sine-Gordon equation (sGe) with suitably chosen boundary conditions. There is adopted an assumption that the normal derivative of the phase order parameter on a border of a junction is given by the surface current distribution on superconductive electrodes. This current distribution can be determined exactly since it makes a linear problem even in a presence of an external magnetic field although the surface current distribution is not uniform and can be singular. A rectangular junction is discussed as an example.