Materials Literature
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Large second hyperpolarizabilities, 〈γxxxx〉, have been measured in solutions of two recently prepared organic polymer superlattices. These compounds have period aromatic and quinoidal structures and differ from each other by a side group substituent. The values observed are 1.6×10−29 esu for the parent copolymer and 3…
Infinitely many lines of zero thickness may be adsorbed onto a plane without overlap, and it is shown that the number of lines adsorbed should scale as 1 3/, where is the number of adsorption trials per unit area of surface. This is confirmed by numerical simulation. The adsorption of ellipses with major and minor axe…
The special properties of calcium aluminate cements make them of value in the construction, mining and refractory industries. This book brings together new international research information on their performance. As well as a state-of-the-art review, it includes reports on studies of: mineralogy, hydration and microst…
Abstract The powders of Bombyx mori silk fibroin were prepared from aqueous solutions of silk fibroin by several kinds of the insolubilization methods, some of which used methanol. The insolubilization appeared to be effected by the conformational transition of silk fibroin from the random coil to antiparallel β‐sheet…
X-ray diffraction analysis (at 2.1-A resolution) of an acid alpha-amylase from Aspergillus niger allowed a detailed description of the stereochemistry of the calcium-binding sites. The primary site (which is essential in maintaining proper folding around the active site) contains a tightly bound Ca2+ with an unusually…
For pt.I see ibid., vol.21, p.3165 (1988). The density-functional theory of freezing is extended to the case of binary mixtures of hard discs viewed as a simple model for monolayers adsorbed on a smooth substrate. The theory is applied to the fluid-disordered crystal transition. The results are similar to those alread…
The long-range behaviour of the orientational fluctuations of a pair distribution function is studied. The existence of the instability of an isotropic liquid against formation of the state with bond orientational order is shown. The estimated for the instability points for a Lennard-Jones liquid are obtained, and a c…
The properties of the ferroelectric IV-VI semiconductor GeTe have been studied as a function of pressure up to 25 GPa at room temperature, by powder X-ray diffraction in a diamond anvil cell. In a truly hydrostatic medium, the transition from the rhombohedral to cubic NaCl-type structure was not observed up to 8 GPa w…
Pyrite films were prepared using the pure elements as source materials: thin iron films were evaporated on quartz substrates and exposed to a sulfur plasma. The process was controlled by a transmission measurement. X-ray spectroscopy was used to characterize the films and preliminary optical and electrical measurement…
The photoconductivity of vacuum-evaporated vitreous selenium films has been found to depend strongly on residual gases which exist in the vacuum chamber. Specific effects depend on whether these gases are the result of increased system outgassing or purge gas leaked into the evaporation chamber. Films that were evapor…
Different solid-state refining techniques can be used to decrease the interstitial impurity level of refractory and other high melting metals. Purification by external gettering is particularly effective for carbon, oxygen and nitrogen in vanadium and niobium. Oxygen and nitrogen can also be readily removed from niobi…
Abstract Yield strength of NaCl: Eu 2+ monocrystals was studied as function of both the dopant concentration and the annealing parameters. Main attention was paid to the strengthening mechanisms induced by the presence of europium related second phases the structure of which was controlled by means of optical methods.…
Abstract 29 Si‐NMR has been used to identify and analyze oligomeric mixtures of diorganyl cyclosiloxanes of the general formula F n D m − n (D = (CH 3 ) 2 SiO, F = CH 3 (CH 2 CH)SiO, m = 3–5 and n = 0 − m ). Chemical shift assignments were confirmed by comparing 29 Si‐NMR and GC‐MS results for composition of the mixt…
The first order Raman spectra and their temperature dependence of lead molybdate single crystals(PbMoO4) have been measured using Argon ion laser(= 5145A) as exciting radiation source. We obtained 13 Raman active modes which are in good agreement with the results of group theory, but 170 cm−1 mode of Ag is found at Ag…
Earlier efforts to investigate the material properties of ceramic (1−x) Pb(Mg⅓Nb⅔)O3−xPbTiO3 (PMN-PT) have primarily been concentrated upon exploring the utility of PMN-PT in applications where the high dielectric constant, low thermal expansion, and large, reproducible electrostrictive strains present in the composit…
Trialkyl amines from triethyl to tristearylamine were quaternized with benzyl chloride and compared for the effect of chain length on the rate of quaternization. Triethylamine reacted about twice as fast as tripropylamine with virtually no chain‐length effect from propyl to stearyl. Results are compared to previous ra…
Various metallization schemes are used to provide conducting layers in IC fabrication. X‐ray fluorescence spectrometry has been utilized to examine the chlorine and fluorine levels in some of these metallization schemes after patterning and etching. The metallization systems investigated include Al‐Si and Al‐Si‐Cu, wi…
Abstract We present an analysis of the critical factors for the determination of surface concentrations from derivative Auger spectra. A new spectroscopic quantity, P σ 2 , should supersede the peak‐to‐peak signal. This quantity is the product of the negative‐peak‐to‐background value, P , multiplied by the square of t…
Thin amorphous selenium (a-Se) films and Se films doped with indium have been prepared by thermal evaporation under high vacuum and controlled deposition conditions. Measurement or DC conductivity made in situ as a function of temperature (in the range room temperature to 400 K) and absorption in the photon energy ran…
Azotobacter vinelandii hydrolyzed melibiose exocellularly, leading to an accumulation of free glucose and galactose in the medium. This enzyme could also be induced by galactose, raffinose, and stachyose. The alpha-galactosidase activity could be detected quantitatively by using p-nitrophenyl-alpha-galactopyranoside a…