Influence of reagent vibration on the stereodynamics of the Li + HF → LiF + H reaction

We investigate the influence of reagent vibration on the stereodynamics of the title reaction by the quasi-classical trajectory on the Aguado-Paniagua2-potential energy surface developed by Aguado et al. (J. Chem. Phys. 1997 106 1013). The cross sections and reaction probability as functions of the reagent vibration are calculated in the centre-of-mass frame. The product angular distributions of p(θ_r), p(φ_r), and p(θ_r, φ_r), which reflect the vector correlation, are also presented and discussed. The results indicate that the vector properties are sensitively affected by the vibrational excitation.     

Short distributed feedback fiber laser with unidirectional output for sensing applications

A short distributed feedback fiber laser with a nearly unidirectional output is fabricated and tested. The short fiber laser is made of a polarization-dependent phase-shift grating fabricated with a vertically polarized 244-nm ultraviolet (UV) laser. A single ∏ phase-shift is introduced to a 2-cm grating at a specified position by directly moving the phase mask during UV beam scanning. Test results show that the laser has a single polarization longitudinal mode with 2.6-mW pump threshold. The backward-to-forward output power ratio is approximately 30:1. The relative intensity noise is -88 dB/Hz, and the linewidth is approximately 10 kHz at 75-mW 980-nm pumping. The unidirectional output and short dimension of this short fiber laser make it very useful in sensing applications, especially in multiplexed sensing applications.     

高效液相色谱-二极管阵列检测法及高效液相色谱-电喷雾串联质谱法测定植物源性蛋白中残留的三聚氰胺

建立了高效液相色谱-二极管阵列检测器(HPLC-DAD)及HPLC-电喷雾串联质谱(ESI-MS/MS)测定植物源性蛋白中残留的三聚氰胺的方法。利用HPLC-DAD进行样品中三聚氰胺的初筛,利用HPLC-MS/MS进行确证。采用三氯乙酸溶液沉淀样品中的蛋白,同时提取目标分析物,质谱检测时样品再经强阳离子固相萃取柱富集净化。HPLC-DAD的检测低限为10 mg/kg,HPLC-MS/MS的检测低限为0.5 mg/kg;HPLC-DA的添加回收率为76%～88%,HPLC-MS/MS的添加回收率为72%～82%(基质匹配曲线校正),两种方法的添加回收率的相对标准偏差(RSD)为3.4%～6.4%。     

测定牛奶中5种青霉素残留量的高效液相色谱柱前衍生法

样品采用乙腈直接提取,离心分离及固相（Ｃ１８柱）净化方式,经衍生后,用液相色谱紫外检测器测定牛奶中５种青霉素残留,方法最小检测质量 度０．００５ｍｇ／Ｌ,回收率范围在６８．９％－１０１．３％之间,相对标准偏差为３．２１％－６．１８％。     

Quasi-classical trajectory investigation on the stereodynamics of Li ＋ DF（v=1-6,j=0）→LiF＋D reaction

In this paper, the stereodynamics of Li ＋ DF → Li F ＋ D reaction is investigated by the quasi-classical trajectory（QCT）method on the ^2A＇ potential energy surface（PES） at a relatively low collision energy of 8.76 kcal/mol. The scalar properties of the title reaction such as reaction probability and cross section are studied with vibrational quantum number of v = 1–6. The product angular distributions P（θr） and P（φr） are presented in the same vibrational level range. Moreover, two polarization-dependent generalized differential cross sections（PDDCSs）, i.e., the PDDCS00 and PDDCS22＋are calculated as well. These stereodynamical results demonstrate sensitive behaviors to the vibrational quantum numbers.     

TiY2N@C80电子结构的第一性原理研究

采用第一性原理方法研究了TiY₂N@C₈₀分子的几何、振动和电子性质．理论计算结果表明TiY₂N@C₈₀分子的电子结构性质明显与Sc₃N@C₈₀和Y₃N@C₈₀的不同,而与TiSc₂N@C₈₀相近．对TiY₂N@C₈₀分子进行载流子掺杂时,其磁性     

耗损型产品的可靠性评估方法

本文研究耗损型产品可靠度的评定方法 .耗损型产品的可靠度随着每次的使用 ,可靠度会有所降低 .根据多次使用的试验数据 ,推断产品在某次使用之后的可靠度 .这是一个变动母体的统计推断问题 .本文在变动母体的假定下给出了耗损型产品可靠度的置信下限     

四溴双酚-A与牛血清白蛋白相互作用的光谱学及电化学研究

采用荧光光谱、同步荧光光谱、三维光谱和循环伏安曲线法研究了溴化阻燃剂四溴双酚-A(TBBPA)与牛血清白蛋白(BSA)的相互作用。研究表明,TBBPA对BSA的内源荧光有显著的猝灭作用,根据不同温度下TBBPA对BSA的荧光猝灭作用及室温的循环伏安曲线,证实猝灭机理为静态猝灭。运用位点模型计算出结合常数KA和结合位点数n,说明TBBPA与BSA仅有1个结合位点。由ΔH0和ΔS0分别为-33.06 kJ/mol和-64.73 J/(mol.K),推断范德华力或氢键在二者结合过程中起主要作用。并通过同步荧光光谱和三维光谱研究了TBBPA对BSA构象的影响,结果表明,TBBPA分子的引入改变了BSA疏水腔内疏水微环境,从而导致BSA的构象发生变化。     

液相色谱-电喷雾串联质谱法同时测定蜂胶保健品中的活性成分和降糖西药

采用超高效液相色谱-电喷雾串联四极杆质谱仪(UPLC-ESI-MS/MS)同时测定蜂胶保健品中14种活性成分和9种违禁降糖西药。蜂胶保健品样品用甲醇稀释,超声波提取,样品溶液经高速离心后过滤。使用ACQUITY UPLC C18反相柱(50 mm×2.1 mm,1.7μm);流动相为0.3%甲酸溶液和乙腈,在梯度条件下分析,目标分析物在多反应监测(MRM)模式下以保留时间和离子对(母离子和两个碎片离子)信息比较进行定性和定量分析。本方法的活性成分检出限(LOD)为0.7～42.0 mg/kg;定量限(LOQ)为2.2～140 mg/kg;活性成分的加标回收率为77.8%～113.6%;违禁降糖西药的LOD为0.1～0.9 mg/kg,LOQ为0.3～2.5 mg/kg;违禁降糖西药的平均回收率为79.3%～108.5%。本方法简便、有效、灵敏,为评价蜂胶保健品质量提供了新的检测方法。