Materials Literature
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The biosynthesis of alpha-isopropylmalate (alphaIPM) synthetase, IPM isomerase, and betaIPM dehydrogenase in Bacillus subtilis can be derepressed in leucine auxotrophs by limiting them for leucine. The derepression of the three enzymes is apparently coordinate. A class of mutants resistant to 4-azaleucine excretes leu…
Abstract It has been recently discovered that polymers craze at low temperatures in the presence of nitrogen or argon. A quantitative theory has been developed which explains (1) the critical temperature above which the phenomenon disappears, (2) the critical stress for nucleating a craze, (3) the effect of strain rat…
This paper treats the statistics of thermally activated glide of a dislocation, modelled as a string of constant tension, through an array of randomly distributed identical immobile point obstacles. The parameters governing thermally activated glide are defined, and equations are developed giving the expected value an…
Abstract A series of energy calculations have been carried out in order to describe the epitaxial crystallization of polyethylene from solution in terms of molecular interactions. The total energy has been computed as the sum of electrostatic, dispersion, and repulsion contributions. The potential energy associated wi…
Directional solidification of the MgO‐MgAl 2 O 4 eutectic yields MgO whiskers in a spinel matrix. Microstructures produced at solidification rates of 0.4 to 30.0 cm/h were studied. The interlamellar spacing agrees with the inverse‐square‐root dependence on solidification rate. Colony‐free microstructures formed in all…
Abstract After examining the mechanism of mixing of elastomer with filler by both internal mixers and open mills, the failure characteristics of an elastomer (extension to break and ratio of elasticity to plasticity) were found to be important properties affecting the filler wetting and dispersion rates. The failure c…
GRACE M. FISCHER; Comparison of Collagen Dynamics in Different Tissues Under the Influence of Estradiol, Endocrinology, Volume 93, Issue 5, 1 November 1973, Pag
Abstract Surface microscopy studies have revealed the phase separation and exudation of a phenol type of antioxidant [4,4′‐thiobis (3‐methyl‐6 tert. butyl phenol)] from polyethylene at concentrations of 0.08 percent by weight. The equilibrium solubility of the antioxidant in polyethylene was estimated to be less than…
Abstract Differential thermal analysis offers a convenient and rapid way of determining stabilization levels in polyolefin compositions. Since it is normally used at temperatures in the fabrication range, it provides a direct readout of processing stability. At the same time, because the chemistry of the polymer syste…
Abstract Rates of oxygen absorption and formation of oxidation products were determined in γ‐initiated oxidations of thin films of high‐ and low‐density polyethylene, atactic and isotactic polypropylene, and of three ethylene–propylene copolymers. Radiation yields G for O 2 absorbed and formation of hydroperoxides dep…
Abstract Oxidations of bulk atactic polypropylene (PP) have been carried out at 22 and 45°C, and the dependence of rate of formation of each product on rate of initiation has been determined. The principal product is PP hydroperoxide, formed in a half‐order reaction. One termination product is polymeric dialkyl peroxi…
DISLOCATION STRUCTURE AND WORK-HARDENING OF COPPER SINGLE CRYSTALS WITH [100] AXIS ORIENTATION I. DISLOCATION ARRANGEMENT AND CELL STRUCTURE OF CRYSTALS DEFORMED IN TENSION Copper single crystals with [100] axis orientation are deformed in tension at room temperature and after load-removal are irradiated with neutrons…
The design and operational features are described for a computer-assisted ellipsometer (called ETA for Ellipsometric Thickness Analyzer), developed to provide reliable, real-time measurement of field-effect transistor gate insulator thickness in a manufacturing environment. ETA illuminates the sample with light of fix…
Abstract Melting and crystallization behavior of virgin polytetrafluoroethylene have been studied using a differential scanning calorimeter. Following quantitative relationship was found between number average molecular weight of polytetrafluoroethylene and the heat of crystallization in the molecular weight range of…
A 3.0-A resolution electron density map of lobster glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.12) was computed. The essentially single isomorphous replacement map was very substantially improved by averaging subunits. NAD binds in an open conformation at sites close to subunit interfaces. The coenzyme binding…
The appearance of smoke was studied by a video tape recorder. A typical smoke consisted of inner zone, inner front, outer zone and outer front. Smoke particles collected at different parts were studied by electron microscopy. They were large and often showed clear-cut habits in the inner front, while they were small a…
Abstract Poly(phenylene sulfides) were synthesized from m ‐benzenedithiol and aromatic dibromides in a basic medium of potassium carbonate in dimethylformamide or dimethylacetamide. The products obtained were slightly off‐white with relatively low melting ranges and had inherent viscosities in the 0.2–0.4 dl/g range i…
Abstract In a study of pressure‐sensitive adhesives prepared from mixtures of natural rubber and three different tackifying resins, it was shown that a tackifying resin may form either one‐ or two‐phase systems with natural rubber. Measurements of the viscoelastic properties of the adhesives show that the effect of ta…
Abstract Volatilization of NH 3 from NH 4 ‐ ‐N salts applied to the surface of a calcareous soil was investigated. Ammonia losses from surface applied NH 4 F, (NH 4 ) 2 SO 4 , and (NH 4 ) 2 HPO 4 were 68, 54, and 51%, respectively, of the added NH 4 ‐ ‐N in 100 hours. Ammonium nitrate, NH 4 Cl, and NH 4 I lost 18, 18,…
A procedure is described for optimizing the extraction of information from the diffraction data of a glass. A least-squares technique that minimizes the spurious detail in the radial distribution function (RDF) at small and large interatomic distances is employed both to isolate that portion of the total intensity fun…