A highly selective dual-channel Hg2+ chemosensor based on an easy to prepare double naphthalene Schiff base

Science China Chemistry - A non-sulfur chemosensor based on an easy to prepare double naphthalene Schiff base is reported for the colorimetric and fluorometric dual-channel sensing of Hg2+ ions by...     

Analyses of f→f Transition Spectra of Ln(DPA)3 3-ComplexeS

A new parameter b characterizing covalent behaviour of 4f orbit has been developed on the basis of spectral properties of trivalent lanthanides and used to tested the interaction between 4f electrons and ligands for many of the lanthanides compounds. The factors influencing covalent bonding and changing law of covalency have been discussed by the new parameter.     

The Synthesis of 1-Phenoxy-3- Arylseleno-2-Propanol

A general and efficient synthetic method of 1-phenoxy-3-arylseleno-2-propanol by reducing diary1 diselenides with sodium borohydride in basic environment and their reaction with epoxypropoxyphenols are described.     

双肋式T形梁力学性能的理论分析

以能量变分原理为基础,考虑了剪滞翘曲应力自平衡条件、剪力滞后和剪切变形等因素,建立了双肋式T形梁广义位移的控制微分方程和自然边界条件,获得了相应广义位移的闭合解.进而以算例为基础讨论了自平衡条件、剪力滞后和剪切变形等因素对双肋式T形梁正应力和挠度的贡献.解析解与有限元数值解吻合更好,说明了本文方法的有效性.     

Dark lump excitations in superfluid Fermi gases

We study the linear and nonlinear properties of two-dimensional matter-wave pulses in disk-shaped superfluid Fermi gases.A Kadomtsev-Petviashvili I(KPI) solitary wave has been realized for superfluid Fermi gases in the limited cases of Bardeen-Cooper-Schrieffer(BCS) regime,Bose-Einstein condensate(BEC) regime,and unitarity regime.Onelump solution as well as one-line soliton solutions for the KPI equation are obtained,and two-line soliton solutions with the same amplitude are also studied in the limited cases.The dependence of the lump propagating velocity and the sound speed of two-dimensional superfluid Fermi gases on the interaction parameter are investigated for the limited cases of BEC and unitarity.     

吸附氢分子的振动态及熵的计算

用第一性原理方法研究了H_2在(MgO)_9及(AlN)_(12)团簇上的吸附态、振动模式及熵.分析表明,吸附体系的振动中有六个简正模式可归为氢分子的振动;由于氢分子质量很小,零点能修正对吸附能有重要影响.利用振动配分函数计算了吸附氢分子的熵,表明吸附态H_2的熵主要决定于较低的同相振动的频率,并不完全与吸附强度相关;在标准大气压下70—350 K的温度范围内,吸附H_2的熵与气态H_2的熵之间存在很好的线性关系,吸附后H_2的熵减小约10.2R.     

基于动量原理的大坡度沥青路面动水压力计算及影响因素分析Calculation and influence factors analysis for hydrodynamic pressure of asphalt pavement with large slope based on momentum theorem

在多雨地区长大纵坡沥青路面是雨天事故多发区域。应用动量定理，建立了沥青路面动水压力的力学计算模型，并系统分析了车辆荷载、行车速度和道路纵坡对动水压力的影响。结果表明，当水膜厚度＜3 mm时，动水压力随车速及车辆荷载的增大而增大，上坡时，动水压力随着纵坡坡度的增大而增大，下坡时，动水压力随着纵坡坡度的增大而减小。当水膜厚度＞3 mm时，动水压力随车速、车辆荷载增大而增大，上坡时，动水压力随着纵坡坡度的增大而增大，下坡时，动水压力随着纵坡坡度的增大呈先缓慢增加然后又缓慢减小的变化趋势；无论是上坡还是下坡，动水压力都随着车轮半径的增大而增大。本研究成果为多雨地区长大纵坡沥青路面重载交通高速行车易发生交通事故提供了理论分析依据。     

液相阴极辉光放电原子发射光谱法高灵敏测定精铜矿中的铅和锌

由于重金属毒性大，且在环境、动物和人体器官中易积聚，因而在矿石开采、冶炼和加工之前，监测其中的微量重金属显得尤为重要。著名的原子光谱仪器，如原子荧光光谱(AFS)、原子吸收光谱(AAS)、电感耦合等离子体(ICP)等已广泛用于各种样品中元素的检测，但它们体积大、能耗高、价格昂贵、气体消耗大，这些缺点严重阻碍了野外现场的连续监测。为了满足分析仪器的微型化趋势，1993年Cserfalvi开发了一种电解液阴极放电原子发射光谱(ELCAD-AES)技术并将其用于分析检测中。该装置中，待测溶液以8～10 mL·min-1的流速从细管顶端溢出，然后沿管壁流入装满电解液的35 mL储液池中，以溢出溶液的液面作为放电阴极，在和流动液体电极相距2～4 mm处放一金属W(Ti)棒为阳极，细管浸入电解液并尖端向上弯曲超出储液池液面1～3 mm，细管顶端溢出的液体流入储液池并通过其中的碳棒与电源负极相连，从而构建放电系统。从那时起，为了提高激发效率和放电稳定性，人们对ELCAD进行了大量改进。基于ELCAD的特点，通过改进放电装置，建立了一种新的液相阴极辉光放电(LCGD)分析系统。该系统中，放电在直径0.5 mm的铂针阳极和内径1 mm的毛细管顶端溢出的溶液阴极之间的间隙中产生。毛细管上端和铂丝之间的间隙为2 mm，毛细管插入石墨管且露出石墨管的距离为2.5 mm。样品溶液以4.5 mL·min-1从毛细管顶端溢出流经石墨管上的凹槽，石墨管和电源负极连接。与ELCAD相比，LCGD的优点在于：Pt针做阳极，可形成尖端放电，从而降低能耗(<60 W)，提高激发效率；蠕动泵管上打结，可降低泵的脉动性，提高放电的稳定性；石墨管链接电源负极，删除ELCAD中的储液池，使样品消耗更少。为了评估方法的分析性能，用LCGD测定了HNO₃-HCl消化的精铜矿样品中的铅和锌。系统研究了放电稳定性以及放电电压、溶液流速、支持电解质和溶液pH对发射强度的影响，并将LCGD与其他ELCAD的分析性能进行比较。此外，用ICP对LCGD的测试结果进行验证，t检验分析两种结果的差异性。结果表明，当电压从620升高到680 V，发射强度逐渐增大，这是因为电压升高，激发能量增大，单位体积内激发的金属原子增多，激发效率提高。考虑到放电稳定性，选择650 V为最佳放电电压。当流速从2.5增加到4.5 mL·min-1时，发射强度增加，这是由于流速增加导致进入放电区的样品量增加，发射强度增强；流速高于4.5 mL·min-1后，发射强度有下降的趋势，这是由于水荷载的增加引起放电区能量密度降低以及过量水加热消耗了用于激发样品的能量，导致激发能量降低。因此，选择最佳流速为4.5 mL·min-1。pH=1的HNO₃具有较高的激发强度，因而选择pH=1为最佳pH。最佳条件下，Pb和Zn的检出限分别为0.38和0.59 mg·L-1，相对标准偏差分别为0.9%和1.2%，功率低于60 W。实验中的检出限与其他类似方法所测结果有一定差距，这可能与所选谱仪有关。固定激发波长下研究发现，放电过程有较好的稳定性。矿石样品中Pb和Zn的回收率在87.6%~107.4％，LCGD测试结果与ICP基本一致，两种方法基本无显著性差异。与ICP相比，LCGD具有低能耗、高激发效率、小型便携等优点。随着进一步改进，有望开发出可用于实时、在线检测金属元素的微型化仪器。     

Friedel–Crafts alkylation between chalcone epoxides and heteroarenes induced by triarylaminium salt

Triarylaminium salt was disclosed as a highly efficient nonmetallic initiator for the Friedel–Crafts reaction between chalcone epoxides and heteroarenes to construct a series of complex β-heteroaryl α-ketols in mild conditions and with good yields. Chalcone epoxides were presented as valuable halogen-free pre-electrophile in Friedel–Crafts alkylation through the formation of the stabilized benzylic cation intermediates. A plausible radical cation chain mechanism was also proposed.     

A simple and an efficient strategy to synthesize multi-component nanocomposites for biosensor applications

We demonstrate that core–shell multi-component nanocomposites can be grown in situ at room temperature by a novel one-step approach without adding any reductant and stabilizer. We have presented a one-step method for the synthesis of multi-component nanocomposites in water solution, the multi-component nanocomposites could be produced directly and quickly in an in situ wet-chemical reaction. Here, Au–polypyrrole (PPy)/Prussian blue (PB) nanocomposites have been synthesized successfully under the same circumstance. With the addition of pyrrole monomers into mixture solutions, the autopolymerization of pyrrole into PPy and AuCl₄⁻ was reduced to elemental Au instantaneously as well as simultaneously. At the same time, PB produced along with elemental Au serving as a catalyst. Furthermore, we investigated the performance of Au–PPy/PB nanocomposites as amperometric sensor toward the reduction of H₂O₂, which displayed high sensitivity, fast response and good stability. The peak current of H₂O₂ increased linearly with the concentration of H₂O₂ in the range from 2.5 × 10⁻⁹ to 1.2 × 10⁻⁶ M, and the low detection limit of 8.3 × 10⁻¹⁰ M (S/N = 3) was obtained. Therefore, this work provides a new pathway to design and fabricate novel multi-component nanocomposites, which have unique characteristics and hold great applications in the fields of sensors, electrocatalysis and others.