He—HF体系的结构和分析势能函数

利用Ｇｕａｓｓｉａｎ９４程序和ＱＣＩＳＤ／６－３１１＋＋Ｇ方法得到Ｈｅ－ＨＦ和Ｈｅ－ＦＨ两种线性平衡结构,计算出了这两种弱结合分子的结构参数、离解能和二阶力常数。在此基础上,利用多体项展式方法民出Ｈｅ－ＨＦ（Ｘ＾１Σ＾＋）体系的分析势能函数,得到的势能面准确地再现了Ｈｅ－ＨＦ和Ｈｅ－ＦＨ两种线性结构。     

鲁西南沿黄县区玉米中铅、镉、砷、铬的重金属含量及健康风险评价

为了评估鲁西南沿黄县区(东明县、牡丹区、鄄城县、郓城县)玉米中铅、镉、砷、铬重金属的污染风险,采集该地区玉米果穗,利用电感耦合等离子体质谱(ICP-MS)仪测定其玉米籽粒中铅、镉、砷、铬的含量,并使用单因子污染指数法、内梅罗综合多因子指数法和目标危险系数法开展玉米籽粒重金属污染评价和健康风险评价。结果表明,鲁西南沿黄县区玉米籽粒中重金属铅、镉、砷、铬的含量均未超出GB 2762—2017中规定的限量,重金属含量以Cr最高;鲁西南沿黄县区P_综和TTHQ均小于1,说明玉米籽粒中的重金属元素含量为清洁安全等级,食用该地区玉米对人体的健康风险较低。     

稀土氧化物提高中高碳钢堆焊试样抗开裂性机制的研究

采用5CrNiMo热锻模具钢作为研究对象，分析了堆焊试样上的裂纹形貌，测定了堆焊残余应力场并进行了数值模拟。在此基础上，分析了稀土氧化物改善堆焊金属结晶组织和变质夹杂物的作用。结果表明：堆焊裂纹主要在粗大的树枝晶之间、夹杂物和热影响区粗大奥氏体晶粒处形成，并且，在堆焊金属中心和热影响区残余拉应力作用下扩展。堆焊金属中加入稀土氧化物能细化一次柱状晶组织；变质夹杂物。同时，降低堆焊金属马氏体相变温度，从而降低上述危险部位的拉应力峰值。     

The discovery of nanometer fringes in laser self-mixing interference

We demonstrate the influences of optical feedback from an external mirror with high reflectivity in a He-Ne laser on self-mixing interference fringes and laser polarization states. When the external mirror is tilted to a certain level, the stable and uniform nanometer resolution fringes are generated. The fringe density is 40 times than that of the conventional self-mixing interference or two beam interference, and has still potential to be improved. Each self-mixing interference fringe corresponds to λ/80 displacement of the external mirror, i.e. 7.91 nm displacement of the external mirror. Moreover, when the movement direction of the external mirror is changed, the polarization flipping between two eigenstates will happen. The potential applications of the results are also discussed.     

仿真水晶成分的鉴定

介绍仿真水晶工艺品成分的鉴定过程。对常见阴、阳离子进行分组、分类检定，并用红外光谱法和差热分析法进行验证，最终确定仿真水晶样品的主要成分为含有部分硅酸盐杂质的铵明矾。鉴定结果对仿真水晶的制作有一定的借鉴意义。     

Ce^4+水解切籽5'-AMP,3'-AMPA和CAMP的原位增强 拉曼光谱研究

首次用原位增强拉曼光谱技术研究了Ce^4+水解切断核苷酸的过程,实验表明在粗糙化的银表面可以得到5'---AMP,3'－AMP和CAMP明显增强的拉曼光谱,Ce^4+水解切断5'--AMP时在2895cm^-1和2950cm^-1处分别出现CH~2的动振峰;3'---AMP中原有CH~2振动峰,当它的磷酸酯键被Ce^4+水解切断时,这些峰则明显减弱,甚至消失,把Ce^4+水解切断CAMP过程的原位拉曼光谱与5'---SAMP同Ce^4+反应以后的拉曼光谱相比较,推测Ce^4+断裂CAMP和3'--AMP时,首先切断CAMP中的一个磷酸酯键,生成5'--AMP和3'---AMP随着反应的进行Ce^4+再逐渐断裂5'--AMP和3'---AMP的磷酸酯键,生成最终产物腺苷。     

Synthesis of cyclic carbonates from epoxides catalyzed by metal–BINOL complexes

Synthesis of cyclic carbonates from CO₂ and terminal epoxides catalyzed by Mg, Ca and In BINOL complexes was achieved without organic solvents. Effects of temperature, CO₂ pressure, reaction time and co‐catalyst on the cycloaddition were investigated. Propylene carbonate was obtained under a CO₂ pressure of 1.2 MPa within 10 hours in a yield of 98% catalyzed by Ca–BINOL at 120°C. The order of catalytic activity of the metal center is Ca > In > Mg. Copyright © 2014 John Wiley & Sons, Ltd.     

ADT-based adaptive back-stepping control for the switched non-affine nonlinear system with uncertain parameters

Nonlinear Dynamics - The adaptive back-stepping control issue for the switched non-affine nonlinear system with the uncertain parameter is addressed in this paper. Inspired by the “extended...     

Novel polymeric ionic liquid microspheres with high exchange capacity for fast extraction of plasmid DNA

A novel polymeric ionic liquid (PIL) microsphere, poly(1-vinyl-3-(2-methoxy-2-oxyl ethyl)imidazolium) hexafluorophosphate, is prepared via W/O emulsion polymerization. Rapid ion-exchange between the anionic moieties of PIL and DNA fragments is demonstrated facilitating the exchange equilibrium to be reached within 1 min. The PIL microspheres exhibit a high capacity of 190.7 μg mg⁻¹ for DNA adsorption. A fast DNA isolation protocol is thus developed with the PIL microspheres as solid phase adsorbent. It is feasible to facilitate DNA adsorption or stripping from the microspheres by simply regulating the concentration of salt. DNA adsorption is facilitated at low salt concentration, while higher concentration of salt entails DNA recovery from the microspheres. In practice, the retained DNA could be readily recovered with 1.0 mol L⁻¹ NaCl as stripping reagent, giving rise to a recovery of ca. 80.7%. The PIL microspheres are used for the adsorption/isolation of plasmid DNA from E. coli cell culture, demonstrating a superior adsorption performance with respect to that achieved by a commercial Plasmid Miniprep Kit.     

Dissimilar material joints with and without free-edge stress singularities: Part I. A biologically inspired design

An integrated experimental and numerical investigation was conducted for removing the free-adge stress singularities in dissimilar material joints. A convex inter-face/joint design, inspired by the shape and mechanics of trees, will result in reduced stress singularities at bimaterial corners for most engineering material combinations.In situ photoelasticity experiments on convex polycarbonate-aluminum joints showed that the free-edge stress singularity was successfully removed. As a result, the new design not only improves the static load transfer capacity of dissimilar meterial joints, but also yields more reasonable interfacial tensile strength evaluation. For convex polycarbonate-aluminum and poly(methyl methacrylate)-aluminum joint specimens, the ultimate tensile load increased up to 81% while the total material volume was reduced by at least 15% over that of traditional butt-joint specimens with severe free-edge stress singularities.