Materials Literature
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Description Stabilization and solidification (S/S) technologies have been used for decades as a final treatment step prior to the disposal of radioactive and chemically hazardous wastes. STP 1240 provides you with the latest technical exchange of S/S information available from both of these scientific communities. The…
trans -1,2-Bis(2-pyrrolyl)ethenes (e.g. 18 − 20 ) are prepared by McMurry-type reductive coupling of the corresponding 2-formylpyrroles. The isomeric 1,1-bis(2-pyrrolyl)ethenes (e.g. 24 ) are prepared as a minor byproduct in the reaction of 2-unsubstituted pyrroles (e.g. 22 ) with acetic anhydride under Friedel−Crafts…
This study deals with the changes in the optical properties of polypropylene fibres (4:1 draw ratio 515 tex polypropylene, Bolton, UK) due to the effect of thermal annealing on its structural characteristics. Changes in the structure of annealed polypropylene fibres at a constant time of 2 h and different temperatures…
Total electron-yield (TEY) detection has long been regarded a method for XAS investigations of surface adsorbates under ultra-high vacuum conditions. Recent work has shown, however, that the technique can also be applied to in situ studies of catalysts under reaction conditions. We have thoroughly investigated the TEY…
It has long been recognized that the interphase, i.e., the region between adjacent phases in heterogeneous materials, is a major factor in determining many of the mechanical, optical, and electronic properties of such systems. Interphases are, in general, not abrupt, but exhibit a gradient in the composition from one…
This paper discusses the results on deposition conditions, rates of polymerization, and properties of carbon disulfide films prepared by two techniques, viz., plasma polymerization and argon-plasma-assisted polymerization of carbon disulfide. A higher rate of polymerization and sulfur content was obtained for carbon d…
Microstructures of reaction-bonded Si3N4 bodies, which were fabricated at 1623 K, have been studied to identify the nitridation mechanism of Si compacts by transmission electron microscopy. The percent nitridation of the Si compacts gradually increases with increasing reaction time. In the sample nitrided for 36 ks, t…
Influence of vulcanization conditions (time, pressure and mould thickness) on the electrical conductivity σ- of a 60 FEF/SBR sample was studied. It was found that the mechanism of conduction is highly affected by the different vulcanization conditions. The minimum conductivity value σmin of this compound increases wit…
The microstructure of the rare-earth intermetallic materials, under some circumstances, is very important in determining their extrinsic physical properties. It is demonstrated that some of the microstructural requirements, such as particle size, crystalline integrity, and the phase purity, etc., can be accomplished i…
The prediction of properties of molecules just on the basis of their chemical structures is desirable to selectively make molecules that have the wanted properties, like biological activity, viscosity, or toxicity. Here, we present an example of a new way to predict a property from the chemical structure of a chemical…
Two novel series of electron-beam photoresists possessing high sensitivity and contrast have been developed based on chemical amplification chemistry. The amplification process relies on the electron-beam-induced generation of acids derived from the decomposition of onium salts to catalytically deblock pendant tert -b…
The synthesis and characterization of regioirregular macrocyclics based on the conformationally flexible 1-(4-hydroxyphenyl)-2-(2-methyl-4-hydroxyphenyl)ethane (MBPE) and α,ω-dibromoalkanes, i.e ., MBPE-(c) X ( z ) (where c stands for cyclic, X = 4, 5, 9, and 11 represents the number of methylenic groups in the flexib…
The effect of reaction pressure in catalytic reforming was studied in a pilot reactor with a commercial Pt−Re/Al 2 O 3 reforming catalyst and a hydrotreated naphtha from a North Sea crude. Reformate and hydrogen yields, research octane numbers (RON), and reformate composition at reactor pressures in the range of 12−25…
Main aim of this paper is to present a mathematical model describing the shrinkage phenomenon of materials undergoing drying processes. The model was constructed using the methods of continuum mechanics and the principles of thermodynamics of irreversible processes.it considers the similtaneous deformation of the drie…
Mechanical alloying (MA) was examined by ball-milling the powder mixtures of various starting compositions, Ti-10, 20, 30, 40, 50, 60, 70, 80, 95 at%Mg plus 2 mass%NaCl powder. NaCl powder was an excellent anti-sticking agent for MA. The process of MA was mainly followed by X-ray diffraction and TEM methods. Super-sat…
The properties of lead zirconate titanate (PZT) thin films were characterized as a function of in-plane biaxial stress. Typical values of P/sub r/ and E/sub c/ for unstressed (i.e. no applied load) sol-gel films were measured using Pt/PZT/Pt/Ti/SiO/sub 2//Si test capacitors and are on the order of 28 /spl mu/C/cm/sup…
The effects of metallic concentrations of Zr, Sn, Nb, Ta, Pd, Mo, Co, Cr, Si, Ni and Fe in the medium on the relative growth ratios of fibroblasts L929, osteoblasts MC3T3-E1 cells and the colony formation ratio of fibroblasts V79 cells were investigated. The change in the relative growth ratio of L929 cells after 346…
The first stage of environmental stress cracking (ESC), namely craze initiation, is discussed. The currently accepted mechanisms of ESC initiation are reviewed and developments in methods of predicting ESC, both in terms of the stress conditions required and the thermodynamics of the polymer andenvironment are discuss…
Nd2Fe14B is currendy the best (highest energy product) hard magnet available. Like mostmagnetic materials, it is rather brittle. The fracture toughness of specimens of commercially available hard magnets were measured using a chevron notch, three-point bend test. Values for Nd2Fe14B magnets ranged from 2.5 to 5.5 MPa√…
Fe2O3-PbO-Bi2O3 glasses were prepared by the press-quenching method and their dc conductivities in the temperature range 373-573K were measured. The glass formation region was found to be Fe2O3=0-30mol%, PbO=0-40mol%, Bi2O3=0-100mol%. The Seebeck coefficients showed these glasses to be p-type semiconductors. The glass…