N,N-二甲基甲酰胺中电沉积制备镁镍储氢合金

采用恒电位沉积法, 选用适宜的添加剂和络合剂, 成功地从N,N-二甲基甲酰胺(DMF)中沉积出致密的黑色Mg-Ni储氢合金膜. 并初步探讨了其共沉积机理. XRD显示沉积层中含有非晶态Mg-Ni相和微晶态Mg相. SEM图及相应能谱图分析表明合金颗粒以团聚状态存在, 合金成分不是很均匀. AAS分析表明沉积合金中Mg的原子摩尔分数达27.3%. LAND电池测试系统测得所镀合金膜的放电比容量最高为172.4 mAh/g.     

INTRAPARTICLE DIFFUSION EFFECTS IN FISCHER-TROPSCH SYNTHESIS Ⅰ. MODELING OF DIFFUSION AND REACTION

IntroductionCatal}ticrcactionsaffcctcdb}'diffosionaIlimitationincatal}'stporcshavcbccnextensive1}dcaltx`ithinlit.rat.rcll~5I.Scvcraltcchniqucsonthcspccialcase0fFischcr-Tropschs}'nthcsis(FTS)t\crcapplicdtocxplorcthebchaviorofthiscatal}ticrcactionundercxpcrimcntalandopcrationaIconditionsI3~5l.It`"ouldbeofvaluctoindicatchcrcthatthcseinvcstigationsx"ercmainl}'bascdonthesimplcstkineticsofthcfirstordcrinH2proposedbyAndersonl6]attheearIystages.However-thesetboents,striCtlyspeaking,areinvalidfor…     

氢化物发生-冷原子吸收光谱法测定化妆品中汞

介绍用氢化物发生-冷原子吸收光谱法在重铬酸钾-硝酸溶液存在下测定化妆品中汞的含量。方法空白值低、灵敏、准确、精密度好，特别适合于化妆品中汞的测定。     

Interaction of tetrandrine with human serum albumin: a fluorescence quenching study.

The interaction of tetrandrine with human serum albumin (HSA) was studied by measuring fluorescence quenching spectra, synchronous fluorescence spectra and ultra-violet spectra. The fluorescence quenching spectra of HSA in the presence of tetrandrine showed that tetrandrine quenched the fluorescence of HSA. The quenching constants of tetrandrine on HSA were determined using the Stern-Volmer equation. Static quenching and non-radiation energy transfer were the two main reasons leading to the fluorescence quenching of HSA by tetrandrine. According to the F?rster theory of non-radiation energy transfer, the binding distances (r) and the binding constants (K(A)) were obtained. The thermodynamic parameters obtained in this study revealed that the interaction between tetrandrine and HSA was mainly driven by a hydrophobic force. The conformational changes of HSA were investigated by synchronous spectrum studies.     

What controls the melting properties of DNA-linked gold nanoparticle assemblies?

We report a series of experiments and a theoretical model designed to systematically define and evaluate the relative importance of nanoparticle, oligonucleotide, and environmental variables that contribute to the observed sharp melting transitions associated with DNA-linked nanoparticle structures. These variables include the size of the nanoparticles, the surface density of the oligonucleotides on the nanoparticles, the dielectric constant of the surrounding medium, target concentration, and the position of the nanoparticles with respect to one another within the aggregate. The experimental data may be understood in terms of a thermodynamic model that attributes the sharp melting to a cooperative mechanism that results from two key factors: the presence of multiple DNA linkers between each pair of nanoparticles and a decrease in the melting temperature as DNA strands melt due to a concomitant reduction in local salt concentration. The cooperative melting effect, originating from short-range duplex-to-duplex interactions, is independent of DNA base sequences studied and should be universal for any type of nanostructured probe that is heavily functionalized with oligonucleotides. Understanding the fundamental origins of the melting properties of DNA-linked nanoparticle aggregates (or monolayers) is of paramount importance because these properties directly impact one's ability to formulate high sensitivity and selectivity DNA detection systems and construct materials from these novel nanoparticle materials.     

Synthesis of Enantiomerically Pure Carbohydrate-Derived Annulated Cyclopentadienes and Ferrocenes

The cyclopentadienes 3a/b/c, 8b/c, 12a/b/d , and 16a/b/d were prepared as mixtures of regioisomers from the D -mannitol-derivatives 1,6,10 , and 14 and transformed into the ferrocenes 17, 18 , and 19 (73%; 38:17:45), 23, 24 , and 25 (70%; 6:42 :52), 26 (31%), and 27 (27%), respectively. Deprotection of 17–19 with HCl/MeOH gave the H₂O-soluble ferrocenes 20–22 ; chloromercuration and iodination of 17 via 29 led to the C₂-symmetric diiodo-ferrocene 30 . The mono(chloromercurio) derivative 28 , obtained as a by-product, was also transformed into 29 . The structure of the ferrocenes 18 and 19 , and of the bis(chloromercurio)ferrocene 29 has been established by X-ray analysis. The starting cyclopentadienes 3 were obtained in 50% yield from 1 by dialkylation of CpNa, followed by thermolysis of the spiro-annulated 2 . Similarly, dimesylate 6 (from 4 ) gave the spiro-annulated diene 7 and the annulated dienes 8 in about equal amounts; thermolysis transformed 7 into 8 (62%). The dienes 12 were prepared in 15% yield from the ditriflate 10 via 11 , the dimesylate 9 proving insufficiently reactive, and the dienes 16 (49%) from 14 via 15 .     

Synthesis and Reactivity of (β-Amino-α-acylalkenyl)phenyliodonium Salts

During the last few years alkenyl(phenyl)iodonium salts have risen from mere chemical curiosities to valuable synthetic intermediates. [1] Because of an excellent leaving group ability of a phenyliodonyl moiety, alkenyl(phenyl) iodonium salts undergo nucleophilic vinyl substitutions under mild conditions, thus providing a useful route for the synthesis of various kinds of olefins. Recently, some of functionalized alkenyl iodonium salts have been prepared. [2]     

Analysis of Equilibrium and Kinetics of Chromium-Fluoride Complexation from Spectroscopic Data via Chemometrics Methods

IntroductionStudies on reversible kinetic systems are consi-dered as a hotspot of chemical and biochemical kineticresearches[1,2]. Of late, some researches have been fo-cused on the simultaneous optimization of the obverseand reverse rate constants[3,4].H…     

A Novel Method for Quantification of Circulating DNA in Serum by Capillary Zone Electrophoresis

In this paper, we first presented a novel method for quantification of circulating DNA in human serum based on capillary zone electrophoresis with laser-induced fluorescence detection (CZE-LIF). The serum was digested by proteinase to release free DNA, and then CZE-LIF system was used for the quantification of total circulating DNA. This method was successfully used to quantify the circulating DNA levels in sera from healthy individuals and certain cancer patients.We found the significantly elevated circulating DNA levels in certain prostate cancer patients. Our results demonstrated that CZE-LIF system has good linearity, excellent sensitivity (0.5 ng/mL DNA),satisfactory reproducibility (RSDs in one day and between days were both less than 5%) and reliability, and is well suitable to the quantification of the circulating DNA in human serum or plasma.     

Ultrathin polymer film formation by collision-induced cross-linking of adsorbed organic molecules with hyperthermal protons

A new synthetic approach for the formation of ultrathin polymer films with customizable properties was developed. In this approach, the kinematic nature of proton collisions with simple organic molecules condensed on a substrate is exploited to break C-H bonds preferentially. The subsequent recombination of carbon radicals gives a cross-linked polymer thin film, and the selectivity of C-H cleavage preserves the chemical functionalities of the precursor molecules. The nature and validity of the method are exemplified with theoretical results from ab initio molecular dynamics calculations and experimental evidence from a variety of characterization techniques. Its applicability is demonstrated by the synthesis of ultrathin polymer films with precursor molecules such as dotriacontane, docosanoic acid, poly(acrylic acid) oligomer, and polyisoprene. The approach is fundamentally different from conventional chemical synthesis as it involves an unusual mix of physical and chemical processes including charge exchange, projectile penetration, kinematics, collision-induced dissociation, inelastic energy transfer, chain transfer, and chain cross-linking.