双峰倍增配平法用于同步、导数-同步荧光法同时测定邻羟基苯甲酸和间羟基苯甲酸

邻羟基苯甲酸（ｏＨＢＡ）和间羟基苯甲酸（ｍＨＢＡ）荧光光谱严重重叠，同步及导数技术虽使选择性有所改善，但仍不能完全分辨开重叠谱。用双峰倍增配平计算法结合同步、一阶导数－同步荧光法对双组分体系（邻羟基苯甲酸／间羟基苯甲酸，ｐＨ１２介质）同时测定。结合计算的两种测定方法精密度、回收率和不同组分间浓度比范围均优于一阶导数－同步荧光法。     

EXAMINATION OF THE SURFACE FREE ENERGY AND ACID-BASE PROPERTIES OF CELLULOSE BY THE COLUMN WICKING TECHNIQUE AND THE CRITICAL PACKING HEIGHT/DENSITY

INTRODUCTIONThe wicking technique has been used to determine the surface energy components of solids[1-7]. Generally, thereare two wicking processes in practice, i.e. thin layer wicking and column wicking. A comparison of the twowicking techniques made by van Oss et al.[2], shows that column wicking has a problem of showing differentpacking density due to some kinds of powder materials, i.e. clay can not give good repacking reproducibility[2].But thin layer wicking has a problem in sample…     

Synthese de derives mono- ou disilicies au niveau d'un carbone fonctionnel

Aliphatic saturated amides treated with Me₃SiCl/Li/THF were found to react in two ways. Either alkoxysilanes, mono- or di-silylated at the functional carbon, or C-silylated amines were obtained dependent of the original amide structure and the experimental conditions. (Me₃Si)₂CHN(SiMe₃)₂ exhibited Physicochemical properties that are particular for hindered rotation about the CN bond. A general mechanism is proposed to explain these results.     

Isotope‐Coded Affinity Tagging Technique Using Avidin Functional Affinity Electrophoresis: An Alternative to an Avidin Affinity Column

Avidin functional affinity electrophoresis (AFAEP) is substituted for an avidin affinity column (AAC) to capture biotinylated peptides in the Isotope‐Coded Affinity Tagging (ICAT) technique which is a valuable tool in quantitative proteomics. In this new technique, the AFAEP‐captured ICAT‐labeled biotinylated peptides are extracted with the biotin tag intact from the polyacrylamide gel piece with aqueous 95% formamide (pH 8.2) at 65 °C for 20 min, and then detected by a matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometer. Bovine serum albumin (BSA) and the ¹²C‐ and ¹³C‐ICAT reagents are used to test this AFAEP‐ICAT technique. The results show that both AFAEP and AAC methods provide quantitative information of the relative amounts of ¹²C‐ and ¹³C‐ICAT‐labeled biotinylated tryptic peptides of BSA in a sample. Compared with AAC, the AFAEP is cheaper to perform, more stringent in capturing the biotinylated peptides, and capable of simultaneously processing multiple samples.     

Hydrophobic interaction chromatography coupled with atomic fluorescence spectrometric detection Effect of the denaturation on the determination of thiolic proteins

Hydrophobic interaction chromatography coupled online with chemical vapour atomic fluorescence spectrometry (HIC-CVGAFS) has been optimized for the analysis of thiolic proteins in denaturing conditions. Proteins are pre-column simultaneously denatured and derivatized in phosphate buffer solution containing 8.0 mol dm⁻³ urea and p-hydroxymercurybenzoate (PHMB) and the derivatized denatured proteins are separated on a silica HIC Eichrom Propyl column in the presence of 8.0 M urea in the mobile phase. Post-column online reaction of derivatized denatured proteins with bromine, generated in situ by KBr/KBrO₃ in HCl medium, allowed the fast conversion of the uncomplexed PHMB and of the PHMB bound to proteins to inorganic mercury also in presence of urea. Hg²⁺, present in solution as Hg²⁺-urea complex, is selectively detected by AFS in a Ar/H₂ miniaturized flame after sodium borohydride reduction to Hg. Under optimized conditions, online bromine treatment gives a 100±2% recovery of both free and protein-complexed PHMB. Denatured glyceraldehyde-3-phosphate dehydrogenase, aldolase, lactate dehydrogenase, trioso phosphate isomerase and β-lactoglobulin have been examined. As the sensitivity and limit of detection of proteins in the HIC-CVGAFS apparatus depends on number of SH groups reacting with PHMB, the denaturation process, which increases the number of PHMB-reactive thiolic groups in proteins, improves the analytical performances of the described system in protein analysis. The detection limit for the denatured proteins examined was found in the range of 10⁻¹⁰-10⁻¹² mol dm⁻³, depending on the considered protein, with linear calibration curves spanning over four decades of concentration.     

Study on the Binding Effect between Cordycepin and Calf Thymus DNA by Circular Dichroism

DNA works as hereditary material and plays vital role in life science. The study of the binding of small molecules complex to DNA has been the focus of intense investigation, owning to their stereo and sequence specific interaction with the double helix1-…     

多色蓝在核酸分子上的Langmuir聚集吸附

用微相吸附-光谱修正（MPASC）新技术研究核酸与多色蓝(PCB)探针分子间的相互作用，分析核酸分子内双静电膜的形成与Langmuir吸附的关联性.通过pH 7.24的介质核酸-PCB反应的光谱研究，测定了结合产物的物理化学参数：结合比1PCB:2DNA-PCB、1PCB:3RNA-PCB, 平衡常数KDNA-PCB=5.42×104， KRNA-PCB=2.82×104,摩尔吸收系数ε(DNA-PCB, 625 nm)=5.65×103（mo1－1•L ）•cm－1， ε(RNA-PCB, 625 nm)=3.85×103 （mol－1•L）•cm－1.结果表明， RNA分子仅形成约60％双螺旋结构链，核酸双螺旋每一周期的负静电沟最大聚集10个PCB分子.该吸附反应用于核酸样品测定，结果良好.     

Topical Problems in Elemental Analysis of Advanced Ceramic Materials

Selected prominent problems in the analysis of advanced ceramic materials are surveyed. The importance of reliability of results is discussed in the field of elemental trace- and microanalysis in view of its interaction with economy, power of detection, local resolution and speciation selectivity. Particular problems in the analysis of major constituents, trace components and microlocal distributions are based on the striking propertics of ceramics; they are exemplified. Analytical assistance must start from the beginning of the production processing, in the preparation of the powdered base materials. Determination of the stoichiometry requires high accuracy and differentiation of chemical species in bulk and surface analysis of ceramic base powders. Element trace determination by direct instrumental methods requires standard reference materials for calibration; these are currently inavailable in a sufficient variety. For optimum reliability and power of detection, element traces must be prepared in isolated form in a small excitation volume for analysis. A review on the state-of-the-art of wet-chemical combined procedures is presented. Decomposition position procedures are emphasized, due to their risk of contributing severe systematic error. Combustion in elementary fluorine is presented for decomposition of refractory materials. The performance of some direct procedures is discussed. Very efficient methods are available for element trace determinations in ceramic materials, offering high detection power. Several approaches for high-resolution local microanalysis in non-conductive ceramic materials are identified as the most promising development in the analysis of sintered compact ceramic products and devices.     

Analysis of trimethylsilyl-isopropylidene derivatives of sorbose by combined gas chromatography- and mass-spectrometry

Summary A method has been developed using gas chromatography — electron impact mass spectrometry for the determination of the di-0-isopropylidene-sorbofuranose and mono-0-isopropylidene-sorbofuranose. The compounds are separated as their trimethylsilyl derivatives on a capillary column coated with the stationary phase SE-52. The mass spectra show that the silylation reaction is quantitiative and that the isopropylidene groups does not change.     

甲烷在Ni表面及La薄膜上激活解离化学吸附

利用分子束技术改变甲烷的平动能E_k来研究E_k及其法向分量E_n对甲烷在Ni表面及La薄膜上激活解离吸附的影响。对CH_4/Ni及CH_4/La系统, 当甲烷的平动能E_k分别低于58.5 kJ·mol~(-1)及52.3 kJ·mol~(-1)时, 没观察到甲烷的解离吸附。当甲烷的平动能超过此阈值时, 即对CH_4/Ni系统, 当Ek=58.5增至63.8 kJ·mol~(-1)时, 初始沾着几率s_0由0至0.54线性增加; 对CH_4/La系统, 当E_k=52.3增至63.8 kJ·mol~(-1)时, S_0由0至0.49线性增加。这些结果表明, 两个系统的化学吸附是不经过前趋态的直接化学吸附。最后求出CH_4/Ni, CH_4/La系统的表观活化能分别为46.8 kJ·mol~(-1)和38.1 kJ·mol~(-1)。