Pressure-induced structural transition and thermodynamic properties of RhN2 and the effect of metallic bonding on its hardness

The elastic constant, structural phase transition, and effect of metallic bonding on the hardness of RhN2 under high pressure are investigated through the first-principles calculation by means of the pseudopotential plane-wave method. Three structures are chosen to investigate for RhN2, namely, simple hexagonal P6/mmm （denoted as SH）, orthorhombic Pnnm （marcasite）, and simple tetragonal P4/mbm （denoted as ST）. Our calculations show that the SH phase is energetically more stable than the other two phases at zero pressure. On the basis of the third-order Birch Murnaghan equation of states, we find that the phase transition pressures from an SH to a marcasite structure and from a marcasite to an ST structure are 1.09 GPa and 354.57 GPa, respectively. Elastic constants, formation enthalpies, shear modulus, Young＇s modulus, and Debye temperature of RhN2 are derived. The calculated values are, generally speaking, in good agreement with the previous theoretical results. Meanwhile, it is found that the pressure has an important influence on physical properties. Moreover, the effect of metallic bonding on the hardness of RhN2 is investigated. This is a quantitative investigation on the structural properties of RhN2, and it still awaits experimental confirmation.     

High-peak-power,single-mode,nanosecond pulsed,all-fiber laser for high resolution 3D imaging LIDAR system

This study presents an eye-safe, single-mode, nanosecond-pulsed, and all-fiber laser source with master- oscillator-power-amplifier configuration at 1 550 nm that is suitable for high-resolution three-dimensional (3D) imaging light detection and ranging (LIDAR) system. The output peak power of 7.6 kW is obtained at the 1.2-ns pulse width and 50-kHz repetition rate. The single-mode pulse laser output ensures the range precision and imaging results of the LIDAR system. The laser is used as a transmitter for the 3D imaging LIDAR system. The detailed characteristics of the LIDAR system and the results of the 3D imaging are presented.     

Identification of the metabolites after oral administration of extract of ziziphi spinosae semen to rats or dogs by high‐performance liquid chromatography/linear ion trap FTICR hybrid mass spectrometry

Ziziphi spinosae semen (ZSS) is a traditional Chinese medicine that has been widely used to treat insomnia and anxiety. Modern pharmacological studies have demonstrated that flavonoids are the main active compounds in ZSS. However, the metabolites and the metabolic pathways of flavonoids in ZSS have not been investigated thoroughly. In this study, a method based on high‐performance liquid chromatography coupled with Fourier transform ion cyclotron resonance mass spectrometry (HPLC/FTICR‐MS) was established to identify the metabolites of flavonoids after oral administration of extract of ZSS to rats or dogs, using parent mass list‐triggered data‐dependent multiple‐stage mass analysis at a resolving power of 50,000 in the external calibration mode. The mass accuracies obtained for all full‐scan analyses were less than 4 ppm (<2 ppm in most cases). A total of 15 compounds were detected in biological samples of rats and dogs, and nine compounds were identified. The metabolic pathways of flavonoids of ZSS in rats and dogs were proposed. The results may help better understand the material basis and pharmacological mechanism of ZSS. Copyright © 2012 John Wiley & Sons, Ltd.     

Radiography of a K_α X-ray source generated through ultrahigh picosecond laser–nanostructure target interaction

Laser-driven ultrafast X-ray sources are widely used for diagnostic radiography. However, there is a large divergence of fast electrons when they are generated by an intense short-pulse laser interacting with a foil target.We design a nanowire array target to achieve a more compact point X-ray source. Fast electrons are confined and guided by the nanowire array structure in order to generate a Kαsource with a small spot size. In our work, the smallest measured source size is comparable to the laser spot size, while the conversion efficiency can reach2.4 × 10-4.     

Multiple-image hiding based on interference principle

A method for hiding multiple images into one image is presented. The method is based on interference principle and double random phase mask method. A uniform plane wave interferes with two beams of light wave carrying information of two encrypted images on an output plane. The obtained interference distribution image contains information of two encrypted images. By using frequency spectrum center shift technique, the two encrypted images can be recovered successfully. Then, the interference distribution is encoded into an index matrix through a host image. The optical encryption system parameters and the host image can all be used as encryption keys, which make encrypted image information safer. Numerical simulation indicates that the method can encrypt more information into one image and reconstruct the encryption image information successfully.     

Effect of defects on strain state in nonpolar a-plane GaN

We have investigated the influence of basal stacking fault (BSF) and impurity related defect on the strain state of a-plane GaN epilayers. Four a-plane GaN epilayers were grown on r-plane sapphire using different growth strategies by metalorganic chemical vapor deposition. It is found that with a growing number of stacking fault, both the anisotropic in-plane strain and compressive out-plane strain along c-axis are relieved. Epitaxial lateral overgrowth with a TiN interlayer is an effective way to relieve in-plane strain and reduce BSF density. The extrapolated lattice parameters free of biaxial strain increase with the normalized yellow luminescence intensity. Hydrostatic strain induced by impurity-related defects is the possible cause of this phenomenon.     

2-(4-取代苄基-1,4-高哌嗪-1-基)-N-(5-溴喹喔啉-6-基)乙酰胺衍生物的合成及正性肌力活性研究

设计合成了一系列2-(4-取代苄基-1,4-高哌嗪-1-基)-N-(5-溴喹喔啉-6-基)乙酰胺化合物,测定其对家兔离体左心房搏出量的影响,对化合物的正性肌力活性进行了初步评价.结果显示,一些衍生物在测试浓度下显示出比上市药物米力农更好的正性肌力活性,其中活性最好的化合物是3f,在浓度为3×10-5mol L-1时,增强左心房搏出量的强度达(6.18±0.06)%[米力农:(2.46±0.07)%].实验中所合成的化合物通过IR,1H NMR,MS和元素分析测试进行了确证.     

A new micromechanical approach of micropolar continuum modeling for 2-D periodic cellular material

In this paper, we present a new united approach to formulate the equivalent micropolar constitutive relation of two-dimensional (2-D) periodic cellular material to capture its non-local properties and to explain the size effects in its structural analysis. The new united approach takes both the displacement compatibility and the equilibrium of forces and moments into consideration, where Taylor series expansion of the displacement and rotation fields and the extended aver-aging procedure with an explicit enforcement of equilibrium are adopted in the micromechanical analysis of a unit cell. In numerical examples, the effective micropolar constants obtained in this paper and others derived in the literature are used for the equivalent micropolar continuum simulation of cellular solids. The solutions from the equivalent analysis are compared with the discrete simulation solutions of the cellu-lar solids. It is found that the micropolar constants developed in this paper give satisfying results of equivalent analysis for the periodic cellular material.     

Visible-light-promoted oxidative difunctionalization of alkenes with sulfonyl chlorides to access β-keto sulfones under aerobic conditions

A mild, practical and efficient strategy to prepare β-keto sulfones has been developed by visible light promoted reactions. This reaction involves Ir(ppy)₂(dtbbpy)PF₆ catalyzed direct funcationalization of alkenes with sulfonyl chlorides under mild conditions. Air was used as oxidant without any additives. The transformation affords the corresponding products in moderate to high yields.