苯三甲酸-水分子为主体晶格的四丁基铵层状包合物的合成与晶体结构

合成了一种新颖的苯三甲酸 -水分子为主体晶格的四丁基铵氢键包合物 ,(C4H9) 4 N+ [1,3 ,5 C6H3 (COOH) 2 (COO-) ]·2H2 O ,并进行了X射线晶体结构分析 .晶体为单斜晶系 ,P2 1 /c空间群 ,a =1 3 62 1( 2 )nm ,b =1 3 691( 2 )nm ,c =1 60 94( 2 )nm ,β =10 9 665 ( 3 )° ,V =2 82 61( 7)nm3 ,Z =4,R1 =0 0 5 0 8,wR =0 12 17.包合物中 ,苯三甲酸阴离子之间通过 3位与 5位羧基形成的O—H…O分子间氢键键连成沿b轴无限延伸的锯齿形长链 .位于长链较大空隙处的单一氢键键连的水分子二聚体 ,同时与两酸根的羧基生成给体氢键 ,形成一条苯三甲酸阴离子 -水分子复合宽带 .位于宽带外侧的 1位羧基与相邻宽带的水分子生成的氢键 ,将这些宽带连成平行于 ( 0 0 1)面的层状氢键主体晶格 .四丁基铵阳离子层填充在相邻主体晶格的层间空隙处 ,构成“三明治”式夹层结构的包合物     

应用化学专业实验教学综合改革探索

简要介绍正在实施的新的应用化学专业实验课程体系及正在开展的“面向 2 1世纪化学实验课程教学综合改革与研究”项目的内容、进展及初步效果     

四-(4-三甲铵苯基)卟啉间接分光光度法测定痕量锌

近年来,四-(4-三甲铵苯基)卟啉〔T(4-TAP)P〕与铜和锌的显色反应条件及其在分析上的应用已有报导,但在测定锌时,受到铜的严重干扰,限制了方法的应用范围。我们在pH4.5醋酸介质中,形成锌络合物,后加入稍为过量的铜,使剩余的试剂全部转化为络合物,用硫酸将溶液酸化至0.15M,这时,仅锌络合物完全分解,通过测定释放出试剂在Soret带的吸光度间接测定锌,以此消除铜的干扰。本方法λ_(max)=432nm,ε_(432)=     

Preliminary research on the relationship between long-range correlations and predictability

By establishing the Markov model for a long-range correlated time series (LRCS) and analysing its evolutionary characteristics, this paper defines a physical effective correlation length (ECL) τ, which reflects the predictability of the LRCS. It also finds that the ECL has a better power law relation with the long-range correlated exponent γ of the LRCS: τ= Kexp (-γ/0.3)+Y, (0 < γ < 1) -- the predictability of the LRCS decays exponentially with the increase of γ. It is then applied to a daily maximum temperature series (DMTS) recorded at 740 stations in China between the years 1960--2005 and calculates the ECL of the DMTS. The results show the remarkable regional distributive feature that the ECL is about 10--14 days in west, northwest and northern China, and about 5--10 days in east, southeast and southern China. Namely, the predictability of the DMTS is higher in central-west China than in east and southeast China. In addition, the ECL is reduced by 1--8 days in most areas of China after subtracting the seasonal oscillation signal of the DMTS from its original DMTS; however, it is only slightly altered when the decadal linear trend is removed from the original DMTS. Therefore, it is shown that seasonal oscillation is a significant component of daily maximum temperature evolution and may provide a basis for predicting daily maximum temperatures. Seasonal oscillation is also significant for guiding general weather predictions, as well as seasonal weather predictions.     

一种新的测定诺氟沙星的化学发光分析法

基于在碱性条件下,诺氟沙星(NFLX)对鲁米诺-过氧化氢(Luminol-H2O2)化学发光体系的化学发光信号有强烈的抑制作用,建立了一种简单、快速、可连续测定诺氟沙星的流动注射化学发光分析新方法.该方法线性范围为7.0×10-8-1.0×10-6mol/L,检出限(3σ)为1×10-8mol/L,对3.0×10-7m...     

Exchange-coupling-induced fourfold magnetic anisotropy in CoFeB/FeRh bilayer grown on SrTiO3(001)

Exchange coupling across the interface between a ferromagnetic (FM) layer and an antiferromagnetic (AFM) or another FM layer may induce a unidirectional magnetic anisotropy and/or a uniaxial magnetic anisotropy, which has been extensively studied due to the important application in magnetic materials and devices. In this work, we observed a fourfold magnetic anisotropy in amorphous CoFeB layer when exchange coupling to an adjacent FeRh layer which is epitaxially grown on an SrTiO₃(001) substrate. As the temperature rises from 300 K to 400 K, FeRh film undergoes a phase transition from AFM to FM phase, the induced fourfold magnetic anisotropy in the CoFeB layer switches the orientation from the FeRh$\langle 110\rangle $ to FeRh$\langle 100\rangle $ directions and the strength is obviously reduced. In addition, the effective magnetic damping as well as the two-magnon scattering of the CoFeB/FeRh bilayer also remarkably increase with the occurrence of magnetic phase transition of FeRh. No exchange bias is observed in the bilayer even when FeRh is in the nominal AFM state, which is probably because the residual FM FeRh moments located at the interface can well separate the exchange coupling between the below pinned FeRh moments and the CoFeB moments.