新方法构筑超分子β-CDP-PAN与表征

用分子自组装的方法制备电流变液分散相材料－超分子包结物β-CDP-PAN微粒,其特别是通过分子自组装可以改变介电微粒的微观结构,进而使包结物的电流变活性比主体（β-CDP）有很大提高。分别采用液相法、固相法和液固协同法制备了包结物,发现固相法和液固协同法具有操作简便、包结反应速度快及制备成本低等特点。用荧光分析、IR及XRD等手段对β-CDP-PAN的结构进行了表征,证实了客体PAN中极性较小的萘环进入了环糊精内腔。     

新方法构筑超分子β-CDP-PAN与表征

用分子自组装的方法制备电流变液分散相材料-超分子包结物β-CDP-PAN微粒, 其特点是通过分子自组装可以改变介电微粒的微观结构, 进而使包结物的电流变活性比主体(β-CDP)有很大提高.分别采用液相法、固相法和液固协同法制备了包结物,发现固相法和液固协同法具有操作简便、包结反应速度快及制备成本低等特点.用荧光分析、 IR及XRD等手段对β-CDP-PAN的结构进行了表征,证实了客体PAN中极性较小的萘环进入了环糊精内腔.     

Pt(100)/离子液体OMIPF6界面结构的STM研究

本文运用电化学扫描隧道显微术研究了离子液体OMIPF₆中Pt（100）表面结构在电化学双层区随电极电位的变化. OMI⁺阳离子在Pt（100）表面形成有序吸附结构,并且在约1.2 V宽的电位区间内稳定地存在Pt（100）表面。在电位负于-0.6 V时,有序吸附结构会发生向无序吸附结构的转变. 在电位正于+0.6 V时,较强的静电排斥力才能克服OMIPF₆与Pt（100）表面之间的化学作用,从而导致OMI+阳离子的脱附. 研究表明,OMI+阳离子具有的较长烷基侧链与Pt金属产生的较强化学相互作用是影响该Pt（100）/ OMIPF6界面结构的重要因素.     

Parametric down-conversion with local operation and two-way classical communication

The decoy-state quantum key distribution protocol suggested by Adachi et al. (Phys. Rev. Lett. 99 180503 (2007)) is proven to be secure and feasible with current techniques. It owns two attractive merits,i.e.,its longer secure transmission distance and more convenient operation design. In this paper,we first improve the protocol with the aid of local operation and two-way classical communication (2-LOCC). After our modifications,the secure transmission distance is increased by about 20 km,which will make the protocol more practicable.     

Deterministically distinguishing a remote Bell state

It has been proven that, with a single copy provided, the four Bell states cannot be distinguished by local operations and classical communications (LOCC). Traditionally, a Bell basis projective measurement is needed to distinguish the four Bell states, which is usually carried out with a local interference between two particles. This paper presents an interesting protocol that allows two remote parties to distinguish four Bell states deterministically. We prove that our protocol of distinguishing remote Bell states is beyond LOCC.     

The reliability of AlGaN/GaN high electron mobility transistors under step-electrical stresses

In spite of their extraordinary performance, AlGaN/GaN high electron mobility transistors (HEMTs) still lack solid reliability. Devices under accelerated DC stress tests (off-state, V_DS =0 state, and on-state step-stress) are investigated to help us identify the degradation mechanisms of the AlGaN/GaN HEMTs. All our findings are consistent with the degradation mechanism based on crystallographic-defect formation due to the inverse piezoelectric effects in Ref. [1] (Joh J and del Alamo J A 2006 IEEE IDEM Tech. Digest p. 415). However, under the on-state condition, the devices are suffering from both inverse piezoelectric effects and hot electron effects, and so to improve the reliability of the devices both effects should be taken into consideration.     

环糊精在手性药物分离分析研究中的应用

环糊精由于自身特殊的手性环境和结构特征,已广泛运用于手性化合物的对映体拆分及分析。对近年来环糊精在各种色谱、质谱及核磁等分析方法中的应用进行了归纳总结,综述了环糊精及其衍生物在手性药物的分离分析方面的研究进展。     

First principle study of nitrogen vacancy in aluminium nitride

In the framework of density functional theory, using the plane-wave pseudopotential method, the nitrogen vacancy ($V_{\rm N})$ in both wurtzite and zinc-blende AlN is studied by the supercell approach. The atom configuration, density of states, and formation energies of various charge states are calculated. Two defect states are introduced by the defect, which are a doubly occupied single state above the valance band maximum (VBM) and a singly occupied triple state below the conduction band minimum (CBM) for wurtzite AlN and above the CBM for zinc-blende AlN. So $V_{\rm N}$ acts as a deep donor in wurtzite AlN and a shallow donor in zinc-blende AlN. A thermodynamic transition level $E({3 + } \mathord{\left/ {\vphantom {{3 + } + }} \right. \kern-\nulldelimiterspace} + )$ with very low formation energy appears at 0.7 and 0.6eV above the VBM in wurtzite and zinc-blende structure respectively, which may have a wide shift to the low energy side if atoms surrounding the defect are not fully relaxed. Several other transition levels appear in the upper part of the bandgap. The number of these levels decreases with the structure relaxation. However, these levels are unimportant to AlN properties because of their high formation energy.     

一种快速测定厌氧污泥活性的顶空气相色谱技术

将含有厌氧污泥的样品放入一顶空样品瓶内,在恒定的温度下平衡,并通过多次顶空抽提的方式对样品瓶中所产生的甲烷量随时间的变化进行气相色谱检测,从而实现厌氧污泥比产甲烷活性的检测。实验表明,多次顶空抽提-气相色谱测定厌氧污泥产甲烷活性的技术用约3 h就可以得出厌氧污泥产甲烷的线性规律,其结果与对比试验的数据相近。因而该方法适用于厌氧污泥活性的快速预测,可大大提高相关厌氧污泥活性测定及废水处理领域研究的效率。     

A hybrid strategy to control uncertain nonlinear chaotic system

In this paper, a new method, based on firefly algorithm(FA) and extreme learning machine(ELM), is proposed to control chaos in nonlinear system. ELM is an efficient predicted and classified tool, and can match and fit nonlinear systems efficiently. Hence, mathematical model of uncertain nonlinear system is obtained indirectly. For higher fitting accuracy, a novel swarm intelligence algorithm FA is drawn in our proposed way. The main advantage is that our proposed method can remove the limitation that mathematical model must be known clearly and can be applied to unknown nonlinear chaotic system.