Materials Literature
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On the basis of realistic tight-binding band-structure calculations, we predict that carbon microtubules exhibit striking variations in electronic transport, from metallic to semiconducting with narrow and moderate band gaps, depending on the diameter of the tubule and on the degree of helical arrangement of the carbo…
Abstract Peroxide initiated graft copolymerization of vinyl trimethoxy silane (VTMO) and vinyl triethoxy silane (VTEO) onto polyethylene (PE) and ethylene propylene copolymer (EPR) was studied. The kinetics of grafting, studied by differential scanning calorimetry, are the same for all the systems and the activation e…
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” opt…
In contrast to virtually all natural diamonds, synthetic diamonds show a considerable, reversible, change in colour upon heating. This colour change from yellow to reddish brown in the type Ib diamonds is especially noticeable above 500 K and is attributed to the interaction of optical transitions at the substitutiona…
Light scattering measurements have been performed on single crystals of the solid solution of silver tantalate-niobate in a temperature range extending from 10 K to about 800 K. The experimental results are analysed and discussed by comparison with dielectric and structural data as functions of temperature and relativ…
A new bistable surface switching device using nematic liquid crystals in bookshelflike geometry is presented. The surface bistability is controlled by an external pulsed electric field of defined polarity, which breaks the surface anchoring and selects the final state from dielectric and flexoelectric couplings. A wri…
The transition from a fluid to solid state is investigated by studying the viscosity of concentrated noncolloidal monodisperse and bidisperse suspensions of hard spheres. The notion of a range of fluidity limits, analogous to glass transition densities, is introduced. Lower bounds to this range are determined and comp…
Abstract The wavelengths of the L series of argon, krypton and xenon, the K series of argon, and the M series of curium were measured by means of wavelength dispersive X-ray microanalysis. The specimens for the investigations were TiC layers which had been HF sputtered under reduced argon pressure by the PVD method, k…
Current UK strategy for decommissioning stainless steel plant used for tritium containment centres on heating/melting the bulk metal to effect release of dissolved gases. However, hydrogen isotope containment vessels used for approximately 20 years with mercury pumps and exposed to air and water impurities, exhibit tr…
The recent results of the Isotope Separation System (ISS) operations at the Tritium Systems Test Assembly (TSTA) with 100 g of tritium indicate that the system generally satisfies design goals, while system stability problems remain to be solved. We configured the ISS system for the three column mode, which is one of…
Abstract A method is developed for determining the environmental stress cracking resistance (ESCR) of blow molded poly(ethylene terephthalate) (PET) containers. By this method, the internal chamber of a container is presurized in 68.9 kPa (10 psi) increments while the outside of the base is being exposed to an environ…
The force of adhesion of an aqueous phase (pH 9.6 borate) to steel in the presence of a xylene solution of hydroxy-terminated polybutadiene increases below the potential of zero charge (-550 mV vs Ag/AgCl). Incorporation of a high molecular weight quaternary ammonium cation in the xylene phase inhibits displacement of…
Abstract Degradable copolymers which respond to external stimuli such as pH, ionic strength, and temperature were successfully prepared by direct polycondensation of L ‐lactic acid (LA), D , L ‐mandelic acid (MA), and 3‐( p ‐hydroxyphenyl)propionic acid (HPPA) without the use of a catalyst at 200°C by bubbling nitroge…
Desilication product (DSP) formed in the Bayer process is difficult to study using electron microscopy because it is masked by iron oxide particles. Differences in the rate of DSP formation under plant and laboratory conditions, which may be due to particle size and hence surface area, are difficult to resolve. Iron o…
X-ray photoelectron spectroscopy was used to analyze a 1 cm2, 0.13 mm thick coupon of polytetrafluoroethylene (PTFE). The material was examined as received from the manufacturer following a cleaning with isopropyl alcohol and trichlorotrifluoroethane. The PTFE coupon was examined with a Hewlett-Packard 5950B ESCA syst…
The crystal structure of 1,4-dibromocubane has been determined by X-ray diffraction. The crystal is monoclinic, P2 1 /n, a = 6.878(1), b = 6.960(7), c = 8.793(2) Å, β = 113.08(2)°, Z = 2, R = 0.055. The C—Br bond length, at 1.926 Å, is shorter than usual and the carbon framework is probably distorted by longer bonds a…
t Introduction Silk consists mainly of fibroin and sericin along with very small amounts of waxy substances, mineral salts and colouring matter. The sericin is also referred to as silk gum and its removal is, therefore, called degumming. The sericin is removed by hydrolytically breaking it into smaller water-soluble f…
The authors discuss stator winding deterioration mechanisms and their consequences. Inspection and test procedures which will detect these mechanisms, as well as programs to arrest them, are also discussed. The analysis is broken down into sections on the slot region of the stator winding and on the end winding region…
It is noted that the moving model and the product model have different variations in the height of minor loops and thus a means of differentiating between the models. Measurements show that, for particulate magnetic recording media, the moving model yields more realistic results and that previous reversible magnetizat…
We have studied a process for filling narrow spaces between adjacent metallic conductors (gaps). The process consists of cycles of deposition of by plasma‐enhanced chemical vapor deposition (PECVD) and sputter etching in Ar. For a fixed process and metal thickness, as the gaps decrease in size, i.e. , as the aspect ra…