拍瓦激光与铜靶作用产生光核中子的数值模拟研究

激光驱动中子源由于中子通量高、短脉冲等特点受到广泛关注。通过辐射流体动力学、粒子动力学和蒙特卡罗三种数值模拟程序的组合使用,对超短强激光与铜靶作用产生光核中子进行了全物理过程模拟。首先使用辐射流体动力学程序获得激光预脉冲产生的预等离子体密度分布,然后将预等离子体输入粒子动力学程序获得超短强激光主脉冲产生的超热电子信息,最后将超热电子输入蒙特卡罗程序得到光核中子。模拟获得了光核中子的产额、能谱和角分布信息,发现采用强度1022 W/cm2激光、直径和厚度均为4 cm的Cu圆柱靶,可以获得产额为1.2108/J的光核中子。     

One-pot solvothermal synthesis of hypercrosslinked porous ionic polymer and its catalytic activity

The hypercrosslinked porous ionic polymer has been synthesized via one-pot polymerization and quaternization of vinyl pyridine and chloromethyl styrene under solvothermal condition. The effects of solvents and synthetic process on the polymer structure were investigated. Polymer from n-butanol showed the highest BET surface area of 555.6 m²/g. The catalytic activities were investigated though the aza-Michael addition and the results showed that the polymer owned even higher activity than homogenous ionic liquid. The high BET surface area, high catalytic activity and high stability made the polymer hold great potential for green chemical processes.     

原子力显微镜在纳米生物材料研究中的应用

在过去的20年里,原子力显微镜(AFM)在纳米生物材料领域有着广泛的应用。AFM可有力地揭示纳米生物材料的表面结构与力学性质,并且可作为纳米加工工具对其进行操作与处理。本文综述了AFM在纳米生物材料中的最新应用进展,包括纳米生物材料的成像与表征,力学性能测量和纳米加工。AFM可用来观察纳米生物材料的表面形貌并对其特征高度和表面粗糙度进行分析,还可对其动态过程进行原位观察。通过AFM相图还可得到有时候高度图无法获取的一些表面特征。AFM力曲线可用于测量针尖与纳米生物材料之间的黏附力及分子内外的相互作用力。AFM纳米压痕技术可用来测量材料的相关力学性质(弹力,杨氏模量,硬度,纳米断裂行为等)。此外,AFM也已经被探索用于精准、可控、可重复地加工纳米生物材料。总之,作为一个强大的纳米技术工具,AFM已成为纳米生物材料相关研究领域的一个理想的表面分析和表面加工工具。     

Evaluation of Chitosan Derivatives Modified Mesoporous Silica Nanoparticles as Delivery Carrier

Chitosan is a non-toxic biological material, but chitosan is insoluble in water, which hinders the development and utilization of chitosan. Chitosan derivatives N-2-Hydroxypropyl trimethyl ammonium chloride (N-2-HACC) and carboxymethyl chitosan (CMCS) with good water solubility were synthesized by our laboratory. In this study, we synthesized mesoporous SiO₂ nanoparticles by the emulsion, and then the mesoporous SiO₂ nanoparticles were modified with γ-aminopropyltriethoxysilane to synthesize aminated mesoporous SiO₂ nanoparticles; CMCS and N-2-HACC was used to cross-link the aminated mesoporous SiO₂ nanoparticles to construct SiO₂@CMCS-N-2-HACC nanoparticles. Because the aminated mesoporous SiO₂ nanoparticles with positively charged can react with the mucous membranes, the virus enters the body mainly through mucous membranes, so Newcastle disease virus (NDV) was selected as the model drug to evaluate the performance of the SiO₂@CMCS-N-2-HACC nanoparticles. We prepared the SiO₂@CMCS-N-2-HACC nanoparticles loaded with inactivated NDV (NDV/SiO₂@CMCS-N-2-HACC). The SiO₂@CMCS-N-2-HACC nanoparticles as delivery carrier had high loading capacity, low cytotoxicity, good acid resistance and bile resistance and enteric solubility, and the structure of NDV protein encapsulated in the nano vaccine was not destroyed. In addition, the SiO₂@CMCS-N-2-HACC nanoparticles could sustain slowly released NDV. Therefore, the SiO₂@CMCS-N-2-HACC nanoparticles have the potential to be served as delivery vehicle for vaccine and/or drug.     

Trost氮杂半冠醚手性配体在不对称催化反应中的应用

双功能手性金属络合物催化的不对称反应是目前有机化学研究的热点之一。本文综述了氮杂半冠醚手性配体与金属有机试剂络合的双金属催化剂,在催化不对称aldol反应、不对称Henry反应、不对称Michael反应、不对称Mannich反应、不对称Friedel-Crafts烷基化反应、不对称炔基化反应、不对称硅氰化反应、共聚反应、去对称化反应以及不对称Nozaki-Hiyama烯丙基化反应体系中的应用进展,重点介绍了不同催化体系对催化剂和反应底物之间立体效应和电子效应的影响,总结了控制反应立体选择性的规律以及有关催化反应的机理。     

Nontrivial Solution for a Kirchhoff Type Problem with Zero Mass

Consider the Kirchhoff type equation \begin{equation}\label{eq0.1}-\left(a+b\int_{\mathbb{R}^{N}}|\nabla u|^{2}\,dx\right) \Delta u=\left(\frac{1}{|x|^\mu}*F(u)\right)f(u)\ \ \mbox{in}\ \mathbb{R}^N, \ \ u\in D^{1,2}(\mathbb{R}^N), ~~~~~~(0.1)\end{equation}where $a>0$, $b\geq0$, $0<\mu<\min\{N, 4\}$ with $N\geq 3$, $f: \mathbb{R}\to\mathbb{R}$ is a continuous function and $F(u)=\int_0^u f(t)\,dt$. Under some general assumptions on $f$, we establish the existence of a nontrivial spherically symmetric solution for problem (0.1). The proof is mainly based on mountain pass approach and a scaling technique introduced by Jeanjean.     

On the origin of reactivity of steam reforming of ethylene glycol on supported Ni catalysts

This paper describes a strategy for producing hydrogen via steam reforming of ethylene glycol over supported nickel catalysts. Nickel plays a crucial role in conversion of ethylene glycol and production of hydrogen, while oxide supports affect product distribution of carbonaceous species. A plausible reaction pathway is proposed based on our results and the literature.     

Anisotropic plasticity of nanocrystalline Ti:A molecular dynamics simulation

Using molecular dynamics simulations,the plastic deformation behavior of nanocrytalline Ti has been investigated under tension and compression normal to the{0001},{1010},and{1210}planes.The results indicate that the plastic deformation strongly depends on crystal orientation and loading directions.Under tension normal to basal plane,the deformation mechanism is mainly the grain reorientation and the subsequent deformation twinning.Under compression,the transformation of hexagonal-close packed(HCP)-Ti to face-centered cubic(FCC)-Ti dominates the deformation.When loading is normal to the prismatic planes(both{1010}and{1210}),the deformation mechanism is primarily the phase transformation among HCP,body-centered cubic(BCC),and FCC structures,regardless of loading mode.The orientation relations(OR)of{0001}HCP||{111}FCC and<1210>HCP||<110>FCC,and{1010}HCP||{110}FCC and<0001>HCP||<010>FCC between the HCP and FCC phases have been observed in the present work.For the transformation of HCP→BCC→HCP,the OR is{0001}α1||{110}β||{1010}α2(HCP phase before the critical strain is defined as α1-Ti,BCC phase is defined as β-Ti,and the HCP phase after the critical strain is defined as α2-Ti).Energy evolution during the various loading processes further shows the plastic anisotropy of nanocrystalline Ti is determined by the stacking order of the atoms.The results in the present work will promote the in-depth study of the plastic deformation mechanism of HCP materials.     

Pixelated transmission‐mode diamond X‐ray detector

Fabrication and testing of a prototype transmission‐mode pixelated diamond X‐ray detector (pitch size 60–100 µm), designed to simultaneously measure the flux, position and morphology of an X‐ray beam in real time, are described. The pixel density is achieved by lithographically patterning vertical stripes on the front and horizontal stripes on the back of an electronic‐grade chemical vapor deposition single‐crystal diamond. The bias is rotated through the back horizontal stripes and the current is read out on the front vertical stripes at a rate of ～1 kHz, which leads to an image sampling rate of ～30 Hz. This novel signal readout scheme was tested at beamline X28C at the National Synchrotron Light Source (white beam, 5–15 keV) and at beamline G3 at the Cornell High Energy Synchrotron Source (monochromatic beam, 11.3 keV) with incident beam flux ranges from 1.8 × 10^?2 to 90 W mm^?2. Test results show that the novel detector provides precise beam position (positional noise within 1%) and morphology information (error within 2%), with an additional software‐controlled single channel mode providing accurate flux measurement (fluctuation within 1%).     

葛根中内源性组分葛根素的生物效应

探究了葛根中主要内源性组分葛根素的生物效应,为葛根的安全使用提供科学依据。将20只Balb/C健康小鼠按体重随机分为2组,即对照组和给药组,每组10只,雌雄各半。给药组小鼠一次性经口灌胃6000 mg·kg-1的葛根素,对照组灌胃等体积溶剂聚乙二醇400,连续观察7 d,每天记录小鼠的一般活动状态、体重及死亡情况。7 d后小鼠经眼眶静脉处取血后处死,解剖观察小鼠心脏、肝脏、肾脏,并经HE染色后进行组织病理学研究。结果表明,葛根素雌雄小鼠的体重变化和心脏、肝脏和肾脏指数与对照组之间无显著性差异（P>0.05）。葛根素组雌性小鼠血清中尿素（Urea, UREA）水平显著高于对照组（P<0.05）;葛根素组雌雄小鼠血清中乳酸脱氢酶（Lactic Dehydrogenase, LDH）和雄性大鼠血清中羟丁酸脱氢酶（Hydroxybutyric Dehydrogenase, HBDH）的含量极显著的低于对照组（P<0.05）。组织病理学研究表明,该剂量下的葛根素对小鼠的肝脏几乎不产生影响,但小鼠存在心肌溶解和肾小管间质局灶性出血。