Materials Literature
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The adsorption of nitrogen over an alumina-supported cobalt catalyst has been studied by means of infrared spectroscopy. An infrared band due to dinitrogen species adsorbed over the catalyst appears at 2214 cm–1 at 93 K. The band shifts to lower frequency by ca. 20 cm–1 in the presence of strongly adsorbed hydrogen, w…
The impurity diffusion coefficient of tin in γ-iron has been determined by the serial sectioning method with the radioactive tracer 113Sn in the temperature range between 1197 and 1653 K. The temperature dependence of the diffusion coefficient shows the linear Arrhenius relationship, expressed byD=(0.845−0.119+0.141)×…
Temperature dependence of electrical conductivity has been studied for hot pressed AlN ceramic having different volume percentage of porosity (0.2 to 15 %) in the temperature range (500 K to 950 K). It has been observed that electrical conductivity decreases by two orders of magnitude as the volume percentage of poros…
For a nematic solution of polydisperse rigid rods the osmotic pressure is proved to be independent of the length distribution and proportional simply to the total number density. This rule holds in the gaussian approximation to the Onsager theory. Its accuracy is demonstrated for bidisperse systems.
SummaryThe surface roughening of commercial purity aluminium for lithographic printing plates is commonly carried out by A. C. etching in dilute acids to produce a fairly uniform distribution of small pits. The uniformity of the etching process is affected by metal structure and composition.Techniques developed to sho…
Some principles of protection afforded by clothing in fire situations are reviewed briefly. Several examples of measurements of heat protective properties are given. The materials covered are single layers of fabrics appropriate for work uniforms, the same type of fabric combined with four popular underwear fabrics, a…
The kinetics of hydration of α-CaSO4·0.5H2O has been studied by calorimetry, analysis of the liquid phase, measurement of the combined water, and electron microscopic observations. Hemihydrate particles dissolve immediately after mixing with water and subsequently form hydrated layers on their surfaces by intrusion of…
The equilibrium constants associated with the inclusion compounds of n-butanol and n-pentanol with α-cyclodextrin in aqueous solutions have been measured using the head-space analysis technique involving gas chromatography. These data confirm that a 1:1 inclusion complex is formed. The kinetics associated with the for…
The dependence of ΔKth on crack size and geometry, and Vickers hardness Hv under stress ratio R=-1 was studied. The effects of crack size and geometry are unified with a geometrical parameter √(area) which is the square root of the area occupied by projecting defects or cracks onto the plane normal to the maximum tens…
Abstract The band structure in the high‐symmetry points of the TIGaSe 2 , Brillouin zone is calculated by the pseudopotential method. The top of the valence band is found to be located at the Γ point. The bottom of the conduction band is located at the line Γ–Y and the additional extremum of this band – at the point Γ…
The ASTM oxygen index, a standard atmospheric pressure test for comparing the flammability of plastics, has been used in combination with other tests to evaluate the suitability of nonmetals for use in oxygen service. In 1983, this test was extended to allow measurements at pressures to 2 MPa (300 psig). This paper de…
Surface-enhanced Raman scattering (SERS) of 3,5-pyridinedicarboxylate on colloidal gold in aqueous media and of the azo dye, dabsyl(N-4-dimethylaminoazobenzene-4′-sulphonyl) aspartate (DABS-ASP), on colloidal gold in ethanol was observed. Enhanced Raman spectra and excitation profiles over wavelengths 457.9–676.4 nm w…
Pulse radiolytic oxidation of zinc tetrakis(hydroxyphenyl)porphyrins in neutral solution results in formation of the π-radical cations which decay via disproportionation over a few ms. In alkaline solution, the hydroxy groups are dissociated and for the ortho and meta isomers the rate of disproportionation is reduced…
SUMMARY The wear algorithm described In this paper has the capability to predict the shapes into which rail vehicle wheels and rails wear in tangent track use. Results of the algorithm applied to a freight car model show that the wheel profiles wear into shapes that are nearly identical for four different wear model f…
The crystal structure of a carbonyl–1-methylimidazole–iron(II) porphyrin complex with one highly hindered face has been determined; the structural parameters indicate that the twelve membered polymethylene bridging chain does not induce steric deformation of the axial carbonyl ligand.
Thermal image furnace melting and twin-roller quenching were used to prepare glasses containing large amounts of rare earth oxides in Ln2O3-MXOY systems (Ln2O3=La2O3, Nd2O3, Y2O3; MXOY=SiO2, Al2O3, TiO2, Nb2O5).The glass-forming regions were found at the following compositions close to the eutectic points of the phase…
General effects of five types of ageing on textiles are examined. The types of ageing discussed are physical, photochemical, thermal, chemical and mechanical. Changes in the structure and properties of textiles that result from each type of ageing are discussed in general terms. This paper is expected to provide conse…
The effect of various surface treatments (grinding, polishing, and pickling) and of prefilming (anodizing and passivation). On the susceptibility of aluminium to pitting in 0·5M NaCl solution at 20°C under various hydrostatic pressures has been studied. It was found that the susceptibility to pitting increased and tha…
A. total often extracts of two plants Pleioceras barteri Baill and Marsdenia latifolia Schum, normally used in folkloric medicine in Nigeria have been screened for their phytoconstituents and implicated biological activity. Nine (90%) of the extracts gave positive test for alkaloids, four (40%) for flavonoids, five (5…
New measurements are reported of the elastic constants and refractive indices of the room temperature nematics RO-TN-200, -201, -403 and E7. The new measured material parameters show that the purely optical field induced first-order Freedericksz transition can not be attained by these materials. However, the first-ord…