A new hydrosol of gold clusters
Reduction of gold(III) ions by tetrakis(hydroxymethyl)phosphonium chloride gives a hydrosol of gold clusters with mean diameter 1.5 nm (average nuclearity about Au170) and smaller.
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Ethylene-vinyl acetate (EVA) copolymers: a general review
Ethylene-vinyl acetate (EVA) copolymers are used extensively in the wire and cable industry for making heat shrinkable insulation, semi-conductive insulation jackets, and flame retardant insulation. A general review of EVA copolymers is given. The following items are reviewed: EVA copolymer development, methods of man…
Monte Carlo investigations of a Gay—Berne liquid crystal
We report extensive Monte Carlo simulations of two systems with 512 and 1000 particles interacting with a Gay–Berne potential with strength parameters (µ= 1, ν= 3) that enhance the side-by-side and end-to-end interactions between the particles. We show that the system has a smectic, nematic and isotropic phase and we…
Surface chemistry of colloidal silver: surface plasmon damping by chemisorbed iodide, hydrosulfide (SH-), and phenylthiolate
The optical changes that occur upon the addition of iodide, iodine, and colloidal silver iodide to a colloidal solution of silver particles 6 nm mean diameter were monitored spectrophotometrically. For small concentrations of added I and I2 formation of less than a monolayer of adsorbate , the changes in the shape of…
Vanadium oxide films for optical switching and detection
Structural, electrical, and optical properties of the polycrystalline films of VO<sub>2</sub>, V<sub>2</sub>O<sub>5</sub>, and mixtures of these two oxides are presented. Resistivity change by a factor larger than 10<sup>3</sup> accompanying the semiconductor-metal phase transition in the VO<sub>2</sub> films is repor…
The use of FTi.r.-a.t.r. spectroscopy to characterize penetrant diffusion in polymers
The diffusion of small molecules in polymers was measured using Fourier transform infra-red-attenuated total reflection (FTi.r.-a.t.r) spectroscopy, a new approach which allows one to study liquid diffusion in thin polymer films in situ. The system used to test this technique was the diffusion of liquid water in polya…
Tonminerale und Tone
Die Tonminerale heben sich durch eine Vielfalt von Reaktionen von allen anderen Mineralen und anorganischen Feststoffen abo Als wichtigste Bestandteile der Tone verleihen sie diesen die besonderen Eigenschaften, die die Menschen in ihren frfiheren Kulturen als Bau-und Gefrulmaterial auszunutzen wuBten. Heute haben die…
Polymer-protected palladium–platinum bimetallic clusters: preparation, catalytic properties and structural considerations
Refluxing mixed solutions of palladium(II) chloride and hexachloroplatinic(IV) acid in ethanol–water (1 : 1, v/v) in the presence of poly(N-vinyl-2-pyrrolidone) results in well dispersed and stable colloidal dispersions of polymer-protected palladium/platinum bimetallic clusters. The UV–VIS absorption spectra and tran…
Classification of partial discharges
For a long time, classification of partial discharges was performed by eye, by studying discharge patterns at the ellipse of an oscilloscope screen. The introduction of digital processing techniques allowed automation of the recognition procedure. These procedures are reported and applied to a number of actual HV cons…
Flashover of insulators in vacuum: review of the phenomena and techniques to improved holdoff voltage
Reviews surface flashover of insulator, primarily in vacuum, although some comments are made about the effect of ambient gases on surface flashover. It presents theoretical mechanisms of surface flashover and pertinent experimental results. The holdoff voltage of insulators depends upon many insulator parameters, such…
A Simple Synthesis of 4,5-Disubstituted 1,2-Dicyanobenzenes and 2,3,9,10,16,17,23,24-Octasubstituted Phthalocyanines
All articles of this category 4,5-Dichloro-1,2-dicyanobenzene (5) was prepared in an overall yield of 49% from 4,5-dichloro-1,2-benzenedicarboxylic acid (1) . The reactions of 5 with phenols, thiophenol and 1-propanethiol led in a nucleophilic displacement reaction to the 4,5-bis(aryloxy)-,4, 5-bis(phenylthio)-and 4,5…
Containerless processing in the study of metallic melts and their solidification
The study of metallic melts, their physical properties, and their solidification behaviour is of relevance to understanding of fundamental principles and to metallurgical applications. Many, if not most, of these properties are extremely sensitive to contamination of the melt by impurities. Consequently, containerless…
Surface modification of polymeric biomaterials with poly(ethylene oxide), albumin, and heparin for reduced thrombogenicity
Appropriate surface modification has significantly improved the blood compatibility of polymeric biomaterials. This article reviews methods of surface modification with water-soluble polymers, such as polyethylene oxide (PEO), albumin, and heparin. PEO is a synthetic, neutral, water-soluble polymer, while albumin and…
High Resolution XPS of Organic Polymers: The Scienta ESCA300 Database (Beamson, G.; Briggs, D.)
Stimulating thoughts about how science is practiced, how it is explained, and how its history is written.
Thermodynamic modeling of hydrothermal synthesis of ceramic powders
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThermodynamic modeling of hydrothermal synthesis of ceramic powdersMalgorzata M. Lencka and Richard E. RimanCite this: Chem. Mater. 1993, 5, 1, 61–70Publication Date (Print):January 1, 1993Publication History Published online1 May 2002Published inissue 1 January 1993https://…
Quasicrystals and crystalline approximants
Over the past seven years, many examples of periodic crystals closely related to quasicrystalline alloys have been discovered. These crystals have been termed approximants, since the arrangements of atoms within their unit cells closely approximate the local atomic structures in quasicrystals. This colloquium focuses…
A first course in electrochemical engineering
PREFACE Electrochemical Engineering may be defined as understanding and development of practical materials and processes which involve electrochemical reactions The discipline includes electrochemical methods of synthesis, process recycling, energy conversion and materials protection. Moreover, its importance must gro…
Convergent evolution of similar enzymatic function on different protein folds: The hexokinase, ribokinase, and galactokinase families of sugar kinases
Kinases that catalyze phosphorylation of sugars, called here sugar kinases, can be divided into at least three distinct nonhomologous families. The first is the hexokinase family, which contains many prokaryotic and eukaryotic sugar kinases with diverse specificities, including a new member, rhamnokinase from Salmonel…
Magnetostriction : theory and applications of magnetoelasticity
This outstanding reference provides a comprehensive discussion of magnetoelasticity based on three accepted descriptions of magnetostriction: elastomagnetic matrices, a group symmetrical description, and a tensor formalism. It explores recent advances that rely mainly on Callen's work and emphasizes the influence of t…
Calculations of electron inelastic mean free paths (IMFPS). IV. Evaluation of calculated IMFPs and of the predictive IMFP formula TPP‐2 for electron energies between 50 and 2000 eV
Abstract We have made additional evaluations of the electron inelastic mean free paths (IMFPs) and of the predictive IMFP formula TPP‐2 presented in papers II and III of this series. Comparisons have been made with other formulae for the IMFPs and electron attenuation lengths (ALs). We find substantial differences bet…