Materials Literature
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Streamer propagation and the streamer to leader transition have been thoroughly investigated for SF 6 and air/SF 6 mixtures under positive impulse conditions. This paper, being the first of two related papers on the matter, concentrates on the streamer corona. Streamer propagation in strongly electronegative gases is…
Using a general expression for the spatial dependence of the temperature determined by a steady-state heat flow equation for a cylindrical X-ray target anode with dimensions much larger than the incident electron beam radius, the radius of the melt region on the anode surface has been calculated as a function of the t…
Stable colour centres can be introduced in single crystals of alkali halides using electrolytic coloration. The powders obtained by crushing these single crystals lose colour very rapidly. Mobile dislocations which are present in far greater abundance in the powders are responsible for the reduced stability. Results o…
Abstract The three ligands H 4 dota, H 4 teta, and H 4 heta give binuclear complexes with Cu 2+ and Ni 2+ , the spectral properties of which have been studied. The structures of Cu 2 (dota)·5H 2 O and Cu 2 (teta)·6H 2 O have been established by X‐ray diffraction analysis.
Abstract The two tetraazamacrocycle‐ N , N ′, N ″, N ‴‐tetraacetic acids H 4 dota and H 4 teta form with Ni 2+ , Cu 2+ , and Zn 2+ (M 2+ ) mononuclear complexes MLH 2 and M′[ML], M′ being an alkaline earth ion. The structures of Ni(H 2 dota) and Cu(H 2 dota) have been solved by X‐ray structure analysis. The metal ions…
The 5RL centre has been produced in natural semiconducting diamond by radiation damage and annealing to about 300 degrees C. The 5RL system is observed in both absorption and cathodoluminescence, and is of interest because the zero-phonon transition couples to local-mode phonons with energies well above those of the l…
Using optical second-harmonic generation as a probe, we have observed polar ordering of ${4}^{\ensuremath{'}}\ensuremath{-}n\ensuremath{-}\mathrm{octyl}\ensuremath{-}4\ensuremath{-}\mathrm{cyanobiphenyl}$ (8CB) molecules in a monolayer at an 8CB-glass interface, but nonpolar ordering at the free surface of 8CB as well…
Durable electrochromic coatings of hydrated nickel oxide were produced by reactive rf magnetron sputtering of Ni followed by treatment in KOH. Spectrophotometry was used to assess the achievable modulation of luminous and solar transmittance and to verify that the studied material is interesting for ‘‘smart window’’ a…
A fundamental limitation of LEED as a surface-structure probe is the complexity of the theory compared with x-ray scattering from solids. By making one full dynamical calculation for a reference structure we express diffraction from modifications of this structure in first-order perturbation theory. This gives a theor…
Abstract A method is described for growing single crystals from a solution where a base’s concentration is controlled so that an adduct to be grown is equilibrated with the solution. A slight difference in its solubilities at two different temperatures is responsible for their growth process. The technique is valuable…
The effects of two commercial chitin synthesis inhibitors, dimilin and polyoxin D, on chitin fiber formation and cell sedimentation for the diatoms Thalassiosira fluviatilis and Cyclotella cryptica (Bacillariophyceae) were investigated. Dimilin treatments for both diatom species were indistinguishable from controls in…
Abstract Quarzglas enthält kleine Mengen Wasser, die beim Erhitzen frei werden. Das daraus beim Transport Von TiOCl oder Von Cr 2 S 3 (+AlCl 3 ) entstehende HCl kann für den Transportvorgang wesentlich sein.
Abstract Crystal defects in calcite containing Na and K ions were investigated by means of a model based on statistical thermodynamics and measurements of thermoelectric power. The varying amount of Na and K ions in the crystal was interpreted on an assumption of ideal solution of the ions as Ca1−x−y\squarex+y[Na2x, K…
The nature of fibre migration, the number of fibres in yarn cross-section and the factors that influence the strength of rotorand ring-spun yarns have been studied. Rotor yarn comprised 15%less fibres in yarn cross-section than the corresponding ring yarn. Fewer fibres in ~arn cross-section in rotor yarn result in les…
The radial packing density of rotor-spun yarn was measured on the basis of the theory reported earlier by the author [J ndian J Text Res, 11 (1986) 26]. The effect of yarn twist and count on the fibre packing density of rotor-spun yarn in comparison with tbat of ring-spun yarn was studied. The packing density of both…
Abstract A supplementary device to a scanning electron microscope allows the simultaneous taking of wide‐angle interferences in the directions of transmission and back reflection of identical specimen areas. A developed computer program simulates the complete reflex system so that the identity with the pattern is obta…
A novel laser-induced CVD apparatus with a direct pattern writing ability by a pyrolytic decomposition of SiH 4 has been developed. With this equipment, a CW argon laser with an output power of 20 W was used. The argon laser beam, which provides localized heating of the substrate, was utilized to decompose gas-phase m…
Electron microscope studies of as-ultraquenched and subsequently crystallized isotactic polybutylene (PB) are described in this paper. Cold shadowing of the as-quenched samples reveals no distinct structure larger than 30 Å in the amorphous PB. When rapidly warmed to room temperature PB crystallizes as microcrystals o…
Despite the availability of several commercial suspension formulations of metronidazole benzoate, there is no official method for its analysis. The conventional analytical method requires extensive extraction following each extraction with evaporation then non-aqueous titration with perchloric acid. The method is time…
011-in-glycerol/water emulsions at various ratios of water to glycerol in the external phase were prepared with Tween 80 and either light mineral oil or soybean oil. A minimum in the droplet size was observed at about 15% w/w water in the external phase of the emulsions. At the same water concentration, a clouding of…