球形钨合金破片空气阻力系数实验研究

 实验研究了理想球形钨合金破片和经历爆轰驱动的球形钨合金破片长距离飞行时的速度衰减规律。实验结果表明：（1）对于理想球形钨合金破片,在同一初始速度条件下,衰减系数为常数,空气阻力系数与初始速度有关,两者成线性关系;（2）对于经历爆轰驱动的球形钨合金破片,由于有轻微的质量损失和变形,速度衰减规律与理想球形钨合金破片有明显的区别,空气阻力系数与飞行速度有关,两者成线性关系。     

无内热激光器运转对抽运光光强的需求条件研究

研究了无内热激光器和激光放大器运转时对抽运光的需求条件.运用激光器的速率方程理论,给出了抽运光所应满足条件的表达式.无内热激光运转时,不仅要求抽运光光强要大于阈值条件,而且要大于某个最小抽运光强(与增益材料性质、抽运光波长、激光波长等有关).以掺镱的KY(WO4)2晶体为无内热激光器的放大介质,计算了抽运光光强应满足的空间分布条件.要使激光器无内热运转,抽运光光强需随激光光强的增大而相应减小.对于无内热激光器,抽运光光强的空间分布与谐振腔前后镜的反射率和增益介质长度密切相关,在谐振腔输出耦合镜反射率不是太低的情况下,腔内抽运光强需近似为均匀分布.     

圆形阵列光电探测系统双目标识别方法

针对双弹丸同时着靶情况下的立靶坐标测量问题,提出一种圆形阵列光电探测系统的双目标识别方法.采用光电探测器件组成1个圆形的探测阵列,并将3个发光角度均为60°的扇形一字线激光器均匀设置于圆形探测阵列上组成探测光幕.当2发弹丸同时穿过探测光幕时,会在圆形探测阵列上产生6个弹丸投影,通过信号处理电路识别6个弹丸投影的中心位置...     

固相萃取/超高效液相色谱-串联质谱法测定儿童化妆品中新康唑等4种抗生素

建立了测定儿童化妆品中新康唑等4种抗生素的超高效液相色谱-串联质谱法(UPLC-MS/MS)。样品经70%乙腈水溶液超声提取后,使用SCX固相萃取小柱净化,以0.1%甲酸水和乙腈作为流动相,经Waters ACQUITY BEH C₁₈(2.1 mm×100 mm,2.5μm)色谱柱分离,使用多反应监测模式(MRM)进行测定。结果表明,4种抗生素线性关系良好,相关系数(r)均为0.999,方法检出限(LOD)和定量下限(LOQ)分别为0.005～0.250μg/g和0.010～0.500μg/g。4种抗生素在3种基质和3个加标水平的平均回收率为89.3%～113%,相对标准偏差(RSD)为0.90%～7.2%。该方法高效、准确、特异性好,满足新康唑等4种抗生素在儿童化妆品中的测定需求。     

自动化学间断分析仪和原子吸收光谱法测定锥栗不同授粉组合果实的元素含量

为探讨锥栗不同授粉组合果实中矿质元素是否也存在花粉直感效应，应用全自动间断化学分析仪和原子吸收光谱法测定了“华栗1号”、“华栗2号”、“华栗3号”和“黄榛”四个锥栗主栽品种自交、异交以及自然授粉的子代坚果中主要矿质元素的含量。结果表明，锥栗不同授粉组合坚果的N，P，K，Ca，Mg，Fe，Zn和Mn八种矿质元素含量差异较为显著，其矿质元素具有明显的花粉直感效应，尤其是铁、锌元素受花粉直感作用的影响较大，“华栗2号”ד黄榛”授粉组合果实铁、锌元素含量最高，分别为162.13和41.79 μg·g-1；“黄榛”ד华栗1号”授粉组合果实中Mn元素含量最高为165.67 μg·g-1，为锰微肥的利用提供了参考；通过主成分分析，评价出19个组合中在矿质元素方面表现最优的授粉组合为“华栗2号”ד黄榛”。该研究结果可为锥栗生产上合理配置授粉树和改善果实品质提供科学的依据。     

傅里叶变换法求解两类简单的薛定谔方程

自由粒子和一维无限深势阱的薛定谔方程的求解是量子力学较为基础的内容.本文采用傅里叶变换对这两类简单的薛定谔方程进行了求解讨论.通过偏微分方程的傅里叶变换解法和偏微分方程作分离变数成常微分方程后的傅里叶变换解法的深入讨论,均得到与有关教材一致的结果,并讨论了这两种方法之间的差别和联系.     

A Unified Boundary Behavior of Large Solutions to Hessian Equations

This paper is concerned with strictly k-convex large solutions to Hessian equations S_k(D~2u(x)) = b(x)f(u(x)), x ∈ ?, where ? is a strictly(k-1)-convex and bounded smooth domain in Rn, b ∈ C~∞(?) is positive in ?, but may be vanishing on the boundary.Under a new structure condition on f at infinity, the author studies the refined boundary behavior of such solutions. The results are obtained in a more general setting than those in [Huang, Y., Boundary asymptotical behavior of large solutions to Hessian equations,Pacific J. Math., 244, 2010, 85–98], where f is regularly varying at infinity with index p k.     

Detection of Reactive Oxygen and Nitrogen Species by Upconversion Nanoparticle-Based Near-Infrared Nanoprobes: Recent Progress and Perspectives

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are essential oxidative metabolites of organisms, which are closely related to physiological, pathological and pharmacological processes. The accurate detection of ROS/RNS is important for the understanding of biological processes, monitoring of pharmacological effects, and predicting the course of disease. The recently developed NIR nanoprobes based on upconversion nanoparticles (UCNPs) hold great prospects in sensitive and deep-tissue detection of ROS/RNS, and considerable progress has been achieved so far. In this review, we systematically summarize the up-to-date advances of UCNPs-based near-infrared (NIR) probes for ROS/RNS sensing, and the potential challenges and perspectives for further research are also highlighted. We envision that such a research field will have a bright future for modern biomedical applications.     

Adsorption Site Regulation to Guide Atomic Design of Ni–Ga Catalysts for Acetylene Semi-Hydrogenation

Atomic regulation of metal catalysts has emerged as an intriguing yet challenging strategy to boost product selectivity. Here, we report a density functional theory-guided atomic design strategy for the fabrication of a NiGa intermetallic catalyst with completely isolated Ni sites to optimize acetylene semi-hydrogenation processes. Such Ni sites show not only preferential acetylene π-adsorption, but also enhanced ethylene desorption. The characteristics of the Ni sites are confirmed by multiple characterization techniques, including aberration-corrected high-resolution scanning transmission electron microscopy and X-ray absorption spectrometry measurements. The superior performance is also confirmed experimentally against a Ni₅Ga₃ intermetallic catalyst with partially isolated Ni sites and against a Ni catalyst with multi-atomic ensemble Ni sites. Accordingly, the NiGa intermetallic catalyst with the completely isolated Ni sites shows significantly enhanced selectivity to ethylene and suppressed coke formation.