冲击压缩下甲烷-空气混合气体状态参数实验研究

 为研究强冲击状态下混入少量空气的甲烷气体的冲击状态参数,利用二级轻气炮加载技术,使加速到5 km/s的钨合金飞片撞击封装有常态下空气混入量依次为零（纯甲烷气体）、1%、5%、10%的甲烷-空气混合气体铝靶。采用六通道瞬态光学高温计记录冲击压缩气体的光辐射历程曲线,得到了相同初始条件下4种不同比例混合气体的冲击状态参数。结果表明,在强冲击压缩下,混合气体的冲击温度随着空气混入比例的增大而增高,冲击波后混合气体存在非平衡辐射过程。采用Saha电离平衡方程,对空气混入量为10%的混合气体的电离度进行了估算。结果表明,常态下空气含量C_air≤10%的甲烷 空气混合气体具有电探针保护能力。     

丝氨酸异构体的电子-分子形状共振态及其解离动力学理论研究

Shape resonances of electron-molecule system formed in the low-energy electron attachment to four low-lying conformers of serine (serine 1, serine 2, serine 3, and serine 4) in gas phase are investigated using the quantum scattering method with the non-empirical model potentials in single-center expansion. In the attachment energy range of 0-10 eV, three shape resonances for serine 1, serine 2, and serine 4 and four shape resonances for serine 3 are predicted. The one-dimensional potential energy curves of the temporary negative ions of electron-serine are calculated to explore the correlations between the shape resonance and the bond cleavage. The bond-cleavage selectivity of the different resonant states for a certain conformer is demonstrated, and the recent experimental results about the dissociative electron attachment to serine are interpreted on the basis of present calculations.     

3种黄酮醇类化合物核磁共振碳谱的理论研究

在B3LYP/6-31G水平下优化了3种黄酮醇类（山奈酚,槲皮素,杨梅素）化合物的几何构型. 在振动分析中,均未出现虚频率. 在B3LYP/6-31G的水平下计算了该类化合物的核磁共振碳谱. 研究结果表明：3种分子均有分子内氢键形成,且分子内氢键的键长为0.17~0.18 nm左右 . 本文讨论了羟基引入之后对邻近C的化学位移的影响. 从取代基对NMR的影响来看,随着取代基对苯环的供电子能力的加强,取代基邻近的一些C的化学位移有所改变.      

Electrospinning of Biomaterials for Vascular Regeneration

Cardiovascular diseases have been the leading cause of morbidity and mortality in the world recently. With the growing aging population accompanied by chronic diseases, such as uremia and diabetes, there is an increasing clinical demand for vascular grafts with proper performance. Although some achievements have been made in the development of tissue-engineered vascular grafts composed of natural and synthetic polymeric materials or decellularized vessels, clinical applications with a diameter of less than 6 mm are still principally derived from autografts, such as autologous saphenous veins. Many challenges remain in anti-thrombosis, rapid endothelialization, modulating the inflammatory response and inhibition of intimal hyperplasia and calcification. In the review, recent progress in the electrospinning of biodegradable polymers for vascular regeneration are summarized, especially from the view of biomechanical factors. Hybrid vascular grafts consisting of natural and synthetic polymers with multicomponent, di-or tri-layers are focused in order to provide novel experiences in biomaterials for applications in this field.     

A broadband self-powered UV photodetector of aβ-Ga2O3/γ-CuI p–n junction

The symmetric Ti/Au bi-layer point electrodes have been successfully patterned on theβ-Ga;O;films which are prepared by metal–organic chemical vapor deposition(MOCVD)and theγ-Cu I films which are prepared by spin-coating.The fabricated heterojunction has a large open circuit voltage(Voc)of 0.69 V,desired for achieving self-powered operation of a photodetector.Irradiated by 254-nm ultraviolet(UV)light,when the bias voltage is-5 V,the dark current(Idark)of the device is 0.47 p A,the photocurrent(Iphoto)is-50.93 n A,and the photo-to-dark current ratio(Iphoto/Idark)reaches about 1.08×10;.The device has a stable and fast response speed in different wavelengths,the rise time(τr)and decay time(τd)are 0.762 s and 1.741 s under 254-nm UV light illumination,respectively.While theτr andτd are 10.709 s and7.241 s under 365-nm UV light illumination,respectively.The time-dependent(I–t)response(photocurrent in the order of10-10 A)can be clearly distinguished at a small light intensity of 1μW·cm;.The internal physical mechanism affecting the device performances is discussed by the band diagram and charge carrier transfer theory.     

基于组态软件和多串口通讯的真空检漏监测系统设计与开发

许 婕,蔡立君,卢 勇,罗 山,张 龙,田培红     

“天光”一号MOPA系统光学元件加工与镀膜的进展

本文阐述了在中国原子能科学研究院“天光一号”ＫｒＦ激光核聚变实验装置上，ＭＯＰＡ系统光学元件加工与镀膜研究工作的进展。实验测量结果表明，加工后的基片表面均方根粗糙度对于Ｋ９光学玻璃与熔融石英玻璃来说分别为σｒｍｓ＝１．８±０．５ｎｍ，σｒｍｓ＝２．０±０．４ｎｍ。镀ＨｆＯ２／ＳｉＯ２高反射膜的光学元件的反射率与破坏阈值分别为Ｒ＞９９．５％，Ｅｔｈ＝１．３０～１．３３Ｊ／ｃｍ２。镀Ａｌ２Ｏ３／ＭｇＦ２增透膜的光学元件的透射率与破坏阈值分别为Ｔ＞９９．５％，Ｅｔｈ＝１．３～１．９７Ｊ／ｃｍ２。     

Synthesis, structural and magnetic properties of the nanocomposite Fe63B23Nd7Y3Nb3Cr1 magnets

The Fe₆₃B₂₃Nd₇Y₃Nb₃Cr₁ nanocomposite magnets in the form of sheets have been prepared by copper mold casting technique. The phase evolution, crystal structure, microstructural and magnetic properties have been investigated in the as-cast and annealed states. The as-cast sheets show magnetically soft behaviors which become magnetically hard by thermal annealing. The optimal annealed microstructure was composed of nanosize soft magnetic α-Fe (19-29 nm) and hard magnetic Nd₂Fe₁₄B (45-55 nm) grains. The best hard magnetic properties such as intrinsic coercivity, _jH_c of 1119 kA/m, remanence, B_r of 0.44 T, magnetic induction to saturation magnetization ratio, M_r/M_s=0.61 and maximum energy product, (BH)_max of 55 kJ/m³ was obtained after annealing at 680 °C for 15 min. The annealing treatment above 680 °C results in non-ideal phase grains growth, which degrade the magnetic properties.     

On perturbation bounds for orthogonal projections

In this paper, we present some new perturbation bounds for the orthogonal projections onto the column and row spaces of a matrix, which improve some existing results. Numerical examples are presented to illustrate our results.