DDQ氧化法合成3-溴-1-（3-氯-2-吡啶基）二1H-吡唑-5-甲酸酯类化合物

以DDQ为氧化剂,对3-溴-1-（3-氯-2-吡啶基）-4,5-二氢-1H-吡唑-5-甲酸酯类化合物进行氧化研究,合成了一系列3-溴-1-（3-氯-2-吡啶基）-1H-吡唑-5-甲酸酯类化合物,其结构经氢谱、碳谱和高分辨质谱分析确证,该方法具有操作简便、产率高、适用范围广等优点．     

三维横向流体诱发直管振动的数值模拟

基于有限体积法和有限元法,结合动网格控制技术,建立了横向流体作用下三维弹性直管流致振动计算的数值模型,实现了计算结构动力学与计算流体力学之间的联合仿真．首先,通过对刚性管的静止绕流计算,研究了网格离散方式和不同湍流模型对圆柱类结构静止绕流流场特征的影响和预测能力,得到了适用于双向耦合分析的CFD模型;其次,利用基于双向流固耦合方法的流致振动模型,计算并分析了流体力与结构位移间的相位关系,指出流体力与位移间的相位差是由流体力引起的,同时对双向耦合和单向耦合进行了比较分析;最后通过对直管流致振动的数值计算,联合管表面压力、尾流区时均速度、分离角等时均量,分析了尾流区的流场特征.     

近红外光谱测定猪眼肌肌内脂肪中脂肪酸含量

为了快速无损测定猪眼肌肌内脂肪中脂肪酸含量,提出了近红外光谱技术检测的新方法。选用气相色谱法作为猪眼肌肌内脂肪中脂肪酸测定的标定方法,采用漫反射光纤探头采集由低密度聚乙烯塑料袋包装的猪眼肌样品的光谱,来测定眼肌内脂肪中脂肪酸的含量。利用光谱专用分析软件Unscrambler9.6, 对采集的光谱用平滑,二阶微分法进行预处理, 用偏最小二乘法(PLS)建立其定量检测模型。用于本实验的样本总数为82,将异常点除去后,将样品分为校正集和检验集。用校正集的样品来建立定标方程,再用它来预测检验集样品的值。结果表明,脂肪酸C14∶0,C15∶1,C16∶0,C16∶1,C18∶0,C18∶1,C18∶2,C18∶3,C20∶1,C20∶4,SFA,MUFA和PUFA校正模型的相关系数分别为0.57,0.76,0.71,0.77,0.62,0.81,0.86,0.91,0.85,0.91,0.67,0.81和0.95。可见, 用该方法测定肌内脂肪中脂肪酸有较高的测定精度,因此,应用近红外光谱对猪眼肌肌内脂肪中脂肪酸含量的快速无损检测具有可行性。     

Observation of Sub-femtosecond Polarization Beats Using Twin Noisy Driving Fields

We study the phase-conjugate polarization interference in a V-type three-level system and obtain an analytic closed form for the second-order stochastic correlation of sum-frequency polarization beat. In our Na vapour atomic system pumped by laser pulse of nano-second timescale duration, we experimentally demonstrate an ultrafast modulation of the four-wave mixing signal intensity with a sub-femtosecond timescale period, corre- sponding to the sum-frequency of the resonant transitions from 3S1/2 to 3Pl/2 and 3P3/2.     

水下宽带源方位估计的克拉美-罗界研究

推导了水下宽带源方位估计的克拉美-罗界(CRB)解析式。它揭示了宽带CRB的特点和影响方位估计性能的因素:(1)单源的宽带CRB可分为两部分:与阵列相关的部分包括阵列结构、目标方位及基阵参考点等因素;与信号相关的部分包括信号频率二阶矩及信噪比等。(2)相互独立的两个目标源,每个源的CRB与单源时相应目标源得到的结果相等。(3)两个相关源之间的夹角大于一个波束宽度时,每个源的CRB与单源结果也很接近。(4)由于信源数估计错误,单源误以为是双源,将使CRB值趋于无穷大。仿真结果验证了理论分析的正确性。因此,宽带CRB除给出宽带方位估计算法的最佳估计性能外,还能从方位估计的角度,为宽带阵列及信号波形设计等提供有益的指导。      

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.     

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.     

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.     

三唑类超分子化学与药物研究新进展

三唑环为含有三个氮原子的五元杂环, 唑环具有芳香性和丰富的电子, 易接受质子和络合金属离子, 因而三唑类化合物易通过配位键、氢键、离子-偶极、阳离子-?、?-?堆积、疏水效应以及范德华力等非共价键力形成超分子聚集体, 表现出许多特殊的性能及生物活性, 具有广泛的潜在应用如作为离子受体、材料、医药等. 近些年来, 相关三唑类超分子化学与医药的研究非常活跃, 发展特别迅速, 已成为十分活跃的热点研究领域. 本文结合自己的工作, 参考国内外近五年文献, 首次系统综述了三唑类化合物作为阳离子和阴离子受体以及三唑类超分子作为发光与磁性材料、医药在抗菌、抗真菌、抗癌等方面的研究与开发近况. 希望本综述对三唑类超分子化学与药物的进一步研发有所启迪.     

微纳尺度无机-有机杂化凝胶固定化木瓜蛋白酶研究

以吸附-絮凝耦合方法制备了微纳尺度的纳米TiO₂-聚丙烯酰胺(polyacrylamide, PAM)杂化凝胶固定化酶. 利用扫描电镜(SEM)、能谱面扫描(EDS)、粒度分析表征了杂化凝胶絮凝酶形貌、尺寸及分散性. 通过对酸碱度有效调控, 以及表面Zeta电位分析, 探寻了酶-纳米复合凝胶静电作用机制. 结果表明, 静电相互作用力对酶的负载和颗粒粒度分布影响较大, 在pH＝7.0, TiO₂和木瓜蛋白酶(papain, PA)质量比为7.5∶1时, 固定化酶负载量达121.84 mg/g, 负载率91.38%|杂化凝胶固定化酶尺寸约为0.444 μm左右, 固定化酶在杂化凝胶载体上高度分散. 该杂化凝胶絮凝酶经过5批次反应后相对酶活力能保持在50%以上. 可见由吸附-絮凝法制备的微纳尺度的杂化凝胶固定化酶, 分散性好, 稳定性好, 酶负载量高, 这是一种利用纳米材料和微纳结构进行固定化酶的新途径.