Materials Literature
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Summary A kinetic and X-ray study of the dehydroxylation of datolite, CaBSiO 4 (OH), has shown that the decomposition occurs very rapidly above 700°C in air, with an activation energy for the reaction of the order of 200 kcal mole −1 . The transformation is topotactic, the dehydroxylated phase being tetragonal with a…
The pressure dependence of the specific heat of high-density polyethylene was determined from simultaneous measurements of thermal conductivity and diffusivity in a cylindrical geometry at 300 K and in the pressure range 0–25 kbar. The thermal conductivity and the diffusivity both increase strongly with pressure, the…
Abstract Molar volumes of substantially amorphous polymers may be calculated by using additive constants derived from constitutive atomic and structural parachor contributions. For 34 polymers, ranging in density from 0.83 to 2.03 g/cm 3 , the greatest error in the calculated molar volume compared with the measured va…
Abstract The far ultraviolet absorptions of aliphatic amino acids such as glycine, alanine, aminobutyric acid, valine, and leucine were measured with their solid thin films down to 120 nm. Four absorption bands arising from the carboxyl group were observed in the 200–140 nm region. It was found that the band positions…
Abstract The efficiency of production of F centres in CaF 2 by X‐irradiation has been studied as a function of temperature and compared with the results of an earlier detailed investigation of SrF 2 [1]. The efficiency begins to fall gradually at about 20 K and at 100 K has reached a very low value. It does not recove…
Polycarbonate is a polymer which exhibits extreme toughness, a pronounced yield behavior, and the ability to flow extensively prior to fracture. These characteristics coupled with its birefringent properties indicate its suitability as a model material for photoelastic analyses. This study treats the photoplastic resp…
High-temperature treatment of thermosensitive dna mutants lysogenic for phage lambda leads to prophage induction and release of phage (at the permissive temperature) in elongation-defective mutants of the genotypes dnaB, dnaE, and dnaG. In initiation-defective mutants no prophage induction occurs at 42 C in mutants of…
Raman spectra of crystalline polyethylene n-C23H43 and n-C44H90 at pressures as high as 40 kbar have been studied at 77 and 298°K, and five bands characteristic of lattice modes have been observed at various pressures. Each of these bands has been assigned to a lattice mode through symmetry arguments and vibrational a…
An attempt has been made to discover the mechanism of iron cementation in clays by comparing the aggregation effected in dispersed pure mineral clay by its exposure to different stages in the active hydrolysis of a ferric chloride solution. Contact of the clay with the early products of the hydrolysis is apparently ne…
Back scattered, conversion electron, Mössbauer spectroscopy was used to study oxide films formed by the thermal oxidation of iron at 225, 350, and 450 C (437, 662, and 842 F). The technique was found to be useful in the study of oxide films from approximately 50 to several hundred Angstroms in thickness without remova…
ADVERTISEMENT RETURN TO ISSUEPREVArticleBis(trifluoromethyl)acetolactone, a Stable a-Lactone'Waldemar Adam, Ju-Chao Liu, and Oswaldo RodriguezCite this: J. Org. Chem. 1973, 38, 12, 2269–2270Publication Date (Print):June 1, 1973Publication History Published online1 May 2002Published inissue 1 June 1973https://doi.org/1…
Isothermal annealing of thermally shocked UO 2 bars (O/M= 2.00 ±0.01) at 1600°, 1800°, and 2000°C caused crack healing, which was determined from recovery of room‐temperature fracture strength. The activation energy for crack healing was ∼0.5 of that for volume diffusion, and healing occurred at the same rate as grain…
Abstract Earlier theoretical work on aggregation in imperfect gases and in solutions of protein molecules is reformulated here in such a way as to be applicable to a number of aggregation systems in solution. The theory is most easily developed for an “osmotic” solution. It is exact, in principle, and in particular do…
The actions of low symmetry crystalline electric fields and the spin-orbit coupling in the t2g4 electronic configuration have been considered for the interpretation of magnetic data (susceptibility. Mössbauer effect, etc.). The results of numerical calculations of the various spin Hamiltonian parameters (D.E.ḡ.Ā.efg)…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCrystal and molecular structure of a salt of the (o-benzoquinone diimine)tetracyanoiron(II) ionGary G. Christoph and Virgil L. GoedkenCite this: J. Am. Chem. Soc. 1973, 95, 12, 3869–3875Publication Date (Print):June 1, 1973Publication History Published online1 May 2002Publis…
The phase relationships in the six component system NaAlSi_3O_8- \nCaAl_2Si_2O_8-Na_2CO_3-H_2O were determined between 650° and 950°C and 1 kb pressure \nalong the joins Ab_(80)An_(20)-Na_2CO_3 and Ab_(50)An_(50)-Na_2CO_3, both with 10 percent H_2O \npresent. The phase relationships are complex. Crystallin…
Congenitally athymic (nude) mice have been shown to accept for their lifetime full thickness, normal human skin grafts without immunosuppressive therapy. The biological and medical significance of the long-term maintenance of human tissues in nonhuman subjects is discussed.
Lattice constants, grain size, electrical conductivity, and luminescence were measured for sintered BaTiO 3 ceramics doped with 0 to 1.2 at.% rare‐earth ions. BaTiO 3 doped with low levels of rare‐earth ions contains grains 10 μm in size and has lattice constants nearly equal to those of undoped ceramics. In this case…
The elastic constants, thermal expansion, thermal conductivity, and heat capacity are reported for a new class of laser hosts-the silicate oxyapatites. For Ca2La8(SiO4)6O2 the five independent elastic constants obtained from sound velocity measurements are C11=1.71, C12=0.62, C33=1.71, C44=0.52, and C13=0.39×1012 dyn/…
Diffusion in lattice arrays reducible to cubic symmetry can be simulated by Monte Carlo procedures. Tracer correlation factors can be derived for diffusion mechanisms in such arrays which include simple solids with point defects and non-stoichiometric materials with complex defect structures subject to defect-defect i…