色氨酸和酪氨酸的双波长荧光光谱的研究

色氨酸 (Ｔｒｐ)和酪氨酸 (Ｔｙｒ)是自身具有荧光的物质 ,然而两者的激发光谱和发射光谱都互相重迭 ,给测定带来了困难。有人曾采用预分离方法[1 ] 、二阶导数荧光测定法[2 ] 等进行测定。本文则研究了色氨酸和酪氨酸在双体系中的双波长荧光光谱。双体系双波长荧光光谱法[3,4] ,是在两个完全独立的体系中选择波长对。结果表明 ,在适当的测定体系和参比体系中 ,不仅可以方便地消除共存部分的相互干扰 ,而且还使灵敏度有较大幅度的提高。1　实验部分1 .1　仪器与试剂日立Ｆ 30 1 0型荧光光度计 ( 1ｃｍ石英液槽 ) ,测定条件 :选择单色器带通 …     

关于仪器分析教材中闪耀波长的讨论

在国内一般仪器分析教材或参考书中,有关光栅单色器的光学性能的讨论,均以线色散率,分辨率和闪耀特性三方面论述.对闪耀特性的解释,各书讨论基本一致,即认为近代光栅采用定向闪耀的办法,将衍射的辐射强度集中在某一需要的波长范围内.但对闪耀波长和闪耀角,各书提法不同,可归结为下列几种:     

物质的颜色是怎样产生的?

在无机化学或者分析化学实验中,面对着五彩缤纷的物质,我们常会遇到这样的提问:物质的颜色是怎样产生的?实验早已证明,光是一种能量形式,常见的白光是由不同波长光混合而成的。在一定波长可见光之间存在着对应的互补关系。当物质选择性地吸收了白光中某种波长光时,它就会呈     

空气中二氧化碳气体滤光相关比对方法的研究

叙述空气中二氧化碳标准气体的气体滤光相关分析方法及其分析条件,对气体滤光相关分析方法的精密度和线性度进行了考察,该法对空气中二氧化碳标准气体测定结果的相对标准偏差小于0.2%(n=7),线性度在±0.1%FS之内.将气体滤光相关分析方法用于CCQM K52空气中二氧化碳的国际比对中,取得了理想的实验结果,比对结果的相对误差为0.07%(n=8).     

用同步荧光光谱测定苯并(a)芘

本文研究了致癌物苯并(a)芘(Bap)的同步荧光光谱测定法,通过选取一定的激发和发射单色器的波长差(△λ)来提高选择性,并用峰高进行定量计算。将此法测定实际样品的结果与环境监测中迄今所用的窄基线法进行了比较,二者一致性很好,且前者更简便,可靠。基本原理在常规的荧光法中,通常是根据所获得的激发光谱和发射光谱进行定性定量分析的。1971年Lloyd首先提出了同步光谱法,在激发和发射单色器间固定一定的波长差(△λ)而     

光致色变的螺吡喃聚合物

一些无机和有机化合物,在某些波长的光作用下,其颜色发生可逆变化,这就是光致色变现象。它具有下述三个主要特点:1,有色和无色亚稳态间的可控可逆变化;2,分子规模的变化过程;3,亚稳态间的变化程度与作用光强度呈线性关系。因此,它在图象显示、光信息存储元件、可变光密度的滤光元件,摄影模版和光控     

721型分光光度计

721型分光光度计是综合我厂原来生产的72型分光光度计、551型双光比色计、583型浦氏光度计等三种仪器的技术指标,并保持其各项优点,改革不合理的结构而制造的一种新产品,仪器的电源部分,单色器,比色部分以及测定读数部分全部装合成一件,便于操作。 721型分光光度计(见图1)可供工厂、矿山、医院以及科研单位的试验室在可见光谱区范围内进行一般的比色分析,仪器具有足够的光量调节范围,可采用有     

同步荧光法同时测定色氨酸、酪氨酸和苯丙氨酸

本文叙述一种新的色氨酸、酪氨酸和苯丙氨酸的同步荧光分析法。介质为KH_2PO_4-NaOH缓冲液(pH=7.4)。以激发单色器和发射单色器的波长差△λ=55nm进行同步扫描,其同步特征峰苯丙氨酸为217nm,酪氨酸为232nm,色氨酸为284nm(均指激发波长)。苯丙氨酸和酪氨酸可直接由其特征峰的高度进行定量测定。色氨酸的284nm特征峰略受酪氨酸同步峰拖尾的影响,其峰值信号需加校正。苯丙氨酸测定范围为0.07-5ppm,酪氨酸为0.02-1ppm,色氨酸为0.001—0.5ppm。     

金纳米团簇介导近红外光催化氧化官能化

<正>近年来,利用光作为绿色能源促进有机合成取得了十分可喜的进展,其在有机小分子合成及功能有机材料开发等方面发挥着越来越重要的作用^[1].光催化有机合成反应中,光催化剂吸收光能通过和底物间的电子转移或者能量转移途径,最终将光能转化为化学能^[2].目前所发展的一些使用较多的光催化剂,其最大吸收波长大多位于蓝光区域.而另一方面,由于发光二极管(LED)光源波长易于调节,     

甲醇-水、乙醇-水体系聚集态的共振散射光谱

自从Ｐａｓｔｅｒｎａｃｋ[1,2]使用普通荧光分光光度计建立共振光散射(ＲＬＳ)技术以来,人们用该技术建立了十分灵敏的蛋白质和核酸的分析方法[3,5]。同时该技术在研究化合物在溶液中的聚集态方面也有了较为广泛的应用,一般认为分子聚集体的形成是引起ＲＬＳ增强的主要原因[6]。已知甲醇、乙醇与水互溶形成均匀的溶液体系,那么在这些溶液体系中是否也存在某种形式的分子聚集体呢?为此本文研究了不同浓度的甲醇水溶液和乙醇水溶液的ＲＬＳ光谱。1　实验部分1 1　试剂和仪器甲醇(上海建鑫化工试剂厂,分析纯,含量%≥99 5);乙醇(安徽特酒总…     

利用手持技术改进测定乙醇分子结构实验

利用压强传感器代替排水集气法,改进测定乙醇分子结构实验的仪器装置,并探索最佳反应条件。另外,设计两个空白实验,结合压强变化曲线对实验误差进行相关讨论。     

光谱仪测试范围的扩展

由于石化行业的生产需要，其材质的使用具有多样性和广泛性，经常会出现顾客委托的测试样品的一个或几个元素跨越光谱仪现有测试程序测量范围的情况。本法通过对光谱仪测试原理的认识，根据光谱仪的测试能力及标样的采集，实现了一个或几个元素测量范围的扩展，并对其测量的影响因素进行了研究。     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

Influence of viscosity of medium on processes of oxygen quenching of excited states of mesoporphyrin

The oxygen quenching rate constants for singlet and triplet excited states of the dimethyl ester of mesoporphyrin IX increase with decreasing viscosity of the medium and reach a maximum at a viscosity of approximately 0.4 mPa·sec, after which the rate constants begin to decrease. The drop in rate constant with increasing fluidity of the medium may be related to a nonequilibrium character of the elementary act in the interaction of the reactants in the solvent cage. In viscous media such as isopropyl alcohol, isobutyl alcohol, and isoamyl alcohol, the reaction radius is greater than the sum of the radii of the reacting particles. The long-range character of these processes is due to the relatively weak dependence of the quenching probability on distance.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 2, pp. 161–167, March–April, 1989.     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

物质分配系数的测定实验改进

实验教学目的是从解决实际问题出发,以实验技术训练和实验设计思想培养为目标。介绍了将单一的物质分配系数测定实验改进为综合实验,提高了实验效果及实验资源利用率。     

Neutral diterpenoids of oleoresins of five species of conifers of Transcarpathia

The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodynkh Soedinenii, No. 6, pp. 812–816, November–December, 1988.     

Calculation of enthalpies of hydrogenation of hydrocarbons

Sets of hydrogen molecule equivalents have been developed which permit the calculation of hydrogenation of different types of carbon-carbon bonds from ab initio total energies (3-21G and 6-31G* basis sets, and, to a more limited extent, for MP2/6-31G* data) of reactants and products. The calculated enthalpies of hydrogenation are in good agreement with experiment for unstrained molecules, with average errors on the order of 2 kcal/mol. The 6-31G* equivalents allow the enthalpies for strained molecules to be calculated accurately, but the 3-21G equivalents do not. The equivalents for both basis sets have been tested by calculating the enthalpies of hydrogenation of carbon-carbon bonds in nitrogen- and oxygen-containing organic molecules, free radicals, and classical carbocations. The results are in good agreement with experiment in most cases.