人工神经网络X射线荧光光谱法测定钢中酸溶铝

建立了一种人工神经网络-X射线荧光光谱法测定钢中酸溶铝的方法，用X射线荧光光谱法测定低合金钢中总铝值，应用所建立的ANN-BP网络模型，输入总铝含量直接预测出酸溶铝含量。同时使用改进的BP算法，避免了神经网络学习中可能产生的麻痹现象。该方法用于钢中酸溶铝的测定，结果满意。     

铝试剂的荧光光谱与荧光量子产率

首次研究了铝试剂的荧光光谱和荧光量子产率,发现pH3至pH12条件下,用紫外光照射铝试剂溶液可以产生荧光,最大激发波长和最大发射波长分别为297nm和409nm,荧光强度与铝试剂浓度之间存在良好的线性关系,线性范围为0.01～3μg/mL,检测下限为0.01μg/mL,以硫酸奎宁为参比,测得铝试剂的荧光量子产率为0.16。     

荧光光谱法测定二氧化硫脲

在碱性加热的条件下,二氧化硫脲将没有荧光效应的硝基苯还原为具有较强荧光效应的苯胺,且苯胺的荧光强度与二氧化硫脲的浓度成线性关系。据此,提出了荧光光谱法测定二氧化硫脲的方法。优化的试验条件如下:1反应溶液的酸度为pH 9.6;21.000g·L-1硝基苯溶液的用量为2mL;3反应温度为70℃;4加热时间为15 min。二氧化硫脲的质量浓度在0.06~1.2mg·L-1范围内与其荧光强度呈线性关系,方法的检出限(3s/k)为3.1μg·L-1。以合成水样为基体进行加标回收试验,所得回收率在93.3%~107%之间。     

偶氮胂酸型荧光试剂测定铝的研究

比较了５种新试剂及偶氮胂－Ｉ的铝铬合物的荧光性能，讨论了试剂结构与性能之间的关系。试验出７－〔（４－甲基－２－胂酸基苯）偶氮〕－８－羟基喹啉－５－磺酸为铝的优良荧光试剂，并用其测定茶叶、含茶叶饲料，以及大白鼠排泄物中的铝和水样中的铝，结果满意。     

荧光光谱法测定奶制品中的三聚氰胺

三聚氰胺能够与荧光素在水溶液中发生作用,使荧光素的荧光强度增强,且在一定浓度范围内,荧光强度与三聚氰胺的浓度成线性关系,据此建立了一种新的测定奶制品中三聚氰胺的荧光分析方法。方法的回归方程为ΔI=178.2ρ(10-6g/L),r=0.9977,线性范围5.00×10-7~1.00×10-5g/L,RSD为1.9%(n=10),检出限为9.85×10-8g/L。采用该方法测定奶粉和液态奶中三聚氰胺的含量,测得的平均回收率分别为95.1%和95.8%。     

X射线荧光光谱法直接测定燃料油中铝、硅、硫、钒

提出了应用波长色散X射线荧光光谱法直接测定燃料油中铝、硅、硫及钒含量的方法,用理论α影响系数及内标法校正基体效应,试样预先在60℃及59 kHz超声水浴中搅拌45 min,达到有效地使样品均匀化.测得铝、硅、钒及硫4元素的检出限依次为1.0,0.9,0.7,0.6 mg·kg-1,对两个已知样品中4元素分别按所提出的方法测定7次,从而计算得方法的相对标准偏差在0.5%～12.6%范围内.对4个燃料油样品分别用此方法及标准方法作了分析,所测得4元素的含量互相吻合.     

荧光光谱法测定氨基酸的新方法

在醋酸 醋酸钠缓冲介质中 ,氨基酸能猝灭壳聚糖 茚三酮体系的荧光。基于此 ,建立了一种新的荧光光谱测定氨基酸的方法 ,探讨了其反应机理及测定条件。方法的线性范围为 0mol·L- 1 ～ 1 2× 1 0 - 4 mol·L- 1 ,已应用于测定果汁饮料     

荧光光谱法测定中成药中微量铅

基于二价铅离子在浓盐酸体系中所形成的PbCl42-配合物在紫外光的照射下发出蓝色荧光的原理,提出了一种测定中成药品中的微量铅的灵敏的荧光分析法。体系的荧光强度与Pb(Ⅱ)的质量浓度在0.02～2.00μg/mL范围内有良好的线性关系,检测下限为8.7×10-3μg/mL。用本法测定了中成药丸及原料药粉中的铅含量,回收率分别介于92 0%～107%和94%～101%之间。     

高效毛细管电泳-激光诱导荧光技术在荧光标记DNA分析中的研究进展

激光诱导荧光检测器是目前最灵敏的检测器之一,已广泛用于毛细管电泳DNA分析中.该文对毛细管电泳-激光诱导荧光技术在DNA分析中3种主要的DNA荧光标记方式:荧光基团共价标记、PCR后标记、内插荧光染料标记进行了综述,并对其发展前景进行了展望.引用了78篇文献.     

Fluorescence resonance energy transfer in dye-labeled DNA

We present the results of molecular modeling of dye-labeled, double-stranded DNA. The structural information obtained from the simulations are used as input to an analysis of energy transfer in this system. The simulations reveal the nature of the interaction between a pair of fluorophores and DNA. The donor, tetramethylrhodamine, TMR, attached to the 5′-end of DNA with a six-carbon tether, interacts primarily with DNA's minor groove, but occasionally stacks against the DNA base pairs. The acceptor, Cy5, attached to the opposite strand at positions n (n = 7, 12, 14, 16, 19, 24, 27), binds in the major groove in two distinct locations on the upper and lower part of the groove. We analyzed in detail the dye-to-dye distances, dipole orientation factors and fluorescence resonance energy transfer (FRET) rates. Tests of the validity of the Förster model were conducted using the transition density cube (TDC) method, which provides the exact Coulombic interaction within a certain model chemistry. Our studies show that the use of long tethers does not guarantee rotational freedom of the dyes, as intended in the experiments. Instead, the tethers allow Cy5 to bind in two different geometries, which causes a large uncertainty in the dye-to-dye distances. Our results also show significant fluctuation in the orientation factor, κ², which, together with uncertainty in dye-to-dye distances, cause considerable uncertainty in interpreting FRET measurements. We suggest that molecular modeling, combined with the TDC method, provides a useful tool in designing and interpreting FRET experiments.     

Flow-injection chemiluminescence assay for ultra-trace determination of DNA using rhodamine B-Ce(IV)-DNA ternary system in sulfuric acid media

A novel flow-injection chemiluminescence method for the determination of DNA at ultra-trace level has been established. In 0.8 M sulfuric acid media, the chemiluminescence of the rhodamine B-cerium (IV) or Ce(IV) system is enhanced by DNA, activated previously by imidazole-HCl buffer solution (pH 7.0). The enhanced intensity of chemiluminescence is in proportion to log DNA concentration 1.0×10⁻⁸ to 0.1 μg ml⁻¹ for herring sperm DNA and 2.0×10⁻⁶ to 0.2 μg ml⁻¹ for calf thymus DNA with 3σ detection limits of 8.3×10⁻⁹ μg ml⁻¹ for herring sperm DNA and 3.5×10⁻⁷ μg ml⁻¹ for calf thymus DNA, respectively. The relative standard deviation for 1.0×10⁻⁴ μg ml⁻¹ herring sperm DNA was 0.99% and 2.0×10⁻³ μg ml⁻¹ for calf thymus DNA was 1.1% (n=11). Using the optimized system, DNA contents in six synthetic samples has been determined with recoveries of 99.5-109.0%. The possible mechanism has also been studied in this paper.     

自猝灭荧光探针法测定DNA

随着现代分子生物学和分子生物技术的发展，体内重要的遗传物质──脱氧核糖核酸（DNA）越来越引起人们的重视，对于DNA探针的研究也日渐深入．DNA探针作为研究DNA的有力工具，在90年代取得了长足的进展，新的靶扩增技术（PCR）已日臻完善，发光标记探针也已经与放射性同位素标记具有同等重要的地位，而且已应用于DNA杂交研究、疾病诊断和食品微生物检测等方面[1~5]．但是，研究开发新的、灵敏度高的DNA探针仍然是十分迫切和有意义的工作．本文报道了一种新的基于水杨酸、邻氨基苯甲酸荧光自碎灭的DNA探针技术，这对筛选灵敏度高…     

Fluorescence Microscopy with 6 nm Resolution on DNA Origami

Resolution of emerging superresolution microscopy is commonly characterized by the width of a point‐spread‐function or by the localization accuracy of single molecules. In contrast, resolution is defined as the ability to separate two objects. Recently, DNA origamis have been proven as valuable scaffold for self‐assembled nanorulers in superresolution microscopy. Here, we use DNA origami nanorulers to overcome the discrepancy of localizing single objects and separating two objects by resolving two docking sites at distances of 18, 12, and 6 nm by using the superresolution technique DNA PAINT(point accumulation for imaging in nanoscale topography). For the smallest distances, we reveal the influence of localization noise on the yield of resolvable structures that we rationalize by Monte Carlo simulations.     

Voltammetric determination of DNA hybridization using methylene blue and self-assembled alkanethiol monolayer on gold electrodes

An electrochemical DNA biosensor based on the recognition of single stranded DNA (ssDNA) by hybridization detection with immobilized complementary DNA oligonucleotides is presented. DNA and oligonucleotides were covalently attached through free amines on the DNA bases using N-hydroxysulfosuccinimide (NHS) and N-(3-dimethylamino)propyl-N′-ethylcarbodiimide hydrochloride (EDC) onto a carboxylate terminated alkanethiol self-assembled monolayers (SAM) preformed on a gold electrode (AuE). Differential pulse voltammetry (DPV) was used to investigate the surface coverage and molecular orientation of the immobilized DNA molecules. The covalently immobilized probe could selectively hybridize with the target DNA to form a hybrid on the surface despite the bases being attached to the SAM. The changes in the peak currents of methylene blue (MB), an electroactive label, were observed upon hybridization of probe with the target. Peak currents were found to increase in the following order: hybrid-modified AuE, mismatched hybrid-modified AuE, and the probe-modified AuE which indicates the MB signal is determined by the extent of exposed bases. Control experiments were performed using a non-complementary DNA sequence. The effect of the DNA target concentration on the hybridization signal was also studied. The interaction of MB with inosine substituted probes was investigated. Performance characteristics of the sensor are described.     

利用荧光标记引物和DNA自动测序仪确定DNA的断裂位点

建立了利用荧光标记引物和DNA自动测序仪进行DNA断裂位点分析的新方法, 该方法简便易行、灵敏度高、重复性好、数据分析客观性强、结果可靠, 适用于各种因素造成的DNA断裂位点的分析.     

荧光猝灭法研究氟比洛芬与DNA相互作用

采用荧光光谱法和紫外光谱法, 在生理条件下(pH=7.40)对氟比洛芬(FP)与脱氧核糖核酸(DNA)的作用方式进行了研究.证实了氟比洛芬通过沟槽结合方式与DNA发生相互作用.实验表明, DNA与氟比洛芬的相互作用为静态猝灭过程,测得结合常数为5.53×10~5 L·mol~(-1),结合位点数为1.12.