Materials Literature
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The formation of the riboflavin precursor, 6,7-dimethyl-8-ribityllumazine, from 5-amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione requires a phosphorylated 4-carbon intermediate which has been designated as Compound X (Neuberger, G., and Bacher, A. (1985) Biochem. Biophys. Res. Commun. 127, 175-181). The enzyme cataly…
This paper is an overview of studies performed at the IBM Thomas J. Watson Research Center on diamondlike carbon (hydrogenated amorphous carbon) films, including some recent results on their tribological properties. The films were prepared by rf plasma-assisted chemical vapor deposition (PACVD) from acetylene. Their s…
An intense source of positive, negative, and neutral carbon clusters using excimer laser ablation of polyimide is described. The detection probability for large masses using a standard channel plate configuration is shown to increase exponentially with ion velocity. The large clusters are formed via aggregation of ato…
Total-energy band calculations using the local-spin-density approximation, the augmented-spherical-wave method, and the fixed-spin-moment procedure are used to investigate the volume dependence of the magnetic and electronic properties of 3d transition metals constrained to cubic environments in one-atom or two-atom u…
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We report a determination of the temperature dependence of the upper critical magnetic fields ${\mathit{H}}_{\mathit{c}2}$ for \ensuremath{\kappa}-(BEDT-TTF${)}_{2}$Cu[N(CN${)}_{2}$]Br, with the use of dc-magnetization measurements that show a well-defined diamagnetic onset. We find large slopes of -20 T/K and -2.2 T/…
Bovine myelin basic protein (MBP) was found to be an excellent in vitro substrate (apparent Km = 50 microM) for MAP (mitogen-activated protein) kinase and can be used in lieu of microtubule-associated protein 2 for purification and functional studies of the enzyme. MBP phosphotransferase activity co-purified with MAP…
Abstract 1. For unswollen vulcanizates, storage modulus ( E ′) decreases with the increase in temperature and decrease in loading and surface area of carbon-black filler. On partial swelling, these effects are much reduced, and E ′ becomes independent of surface area and loading on equilibrium swelling. 2. Loss modulu…
Exchangeable Al in subsoils of Ultisols in the southeastern USA can restrict rooting depth. Downward movement of basic cations (Ca, Mg, and K), applied as lime and fertilizer, may diminish that restriction over time. Materials from the argillic horizon were collected from three paired sites, having managed (long-term…
Abstract Imidization of polyamic acid prepared from pyromellitic dianhydride and 4,4′‐methylenedianiline was investigated at 373–493 K. At a certain degree of imidization, depending on the reaction temperature, the reaction is significantly slowed down. For this reason, imidization was divided into two phases, a fast…
A mathematical model for forced‐flow chemical vapor infiltration (CVI) for densification of porous ceramic composites is presented. The process consists of mass transport of reactants by both convection and diffusion into a porous preform, decomposition of reactants, and subsequent deposition of solid product on pore…
The ferromagnetic Heusler alloy Pd2MnSn shows large reduction in magnetization by cold working, without any appreciable change in the Curie temperature. In order to clarify the relationship between the reduction and the defect structure in Pd2MnSn, transmission electron microscopic observation, high-resolution neutron…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPreparation of electrically conducting indium-tin-oxide thin films by heat treatment of mixed-metal hydroxide dispersion containing polymer binderTakaki Kanbara, Masayuki Nagasaka, and Takakazu YamamotoCite this: Chem. Mater. 1990, 2, 6, 643–645Publication Date (Print):Novem…
The bifunctional enzyme involved in tyrosine biosynthesis, chorismate mutase-prephenate dehydrogenase, has been isolated from extracts of a plasmid-containing strain of Escherichia coli K12 and purified to homogeneity by a modified procedure that involves chromatography on both Matrex Blue A and Sepharose-AMP. Detaile…
Article Elastic and thermoelastic properties of isotypic KClO4, RbClO4, CsClO4, TlClO4, NH4ClO4, TlBF4, NH4BF4 and BaSO4 was published on November 1, 1990 in the journal Zeitschrift für Kristallographie - Crystalline Materials (volume 192, issue 1-4).
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTConcentrated emulsions. Investigation of polydispersity and droplet distortion and their effect on volume fraction and interfacial areaAshok K. Das and Pushpito K. GhoshCite this: Langmuir 1990, 6, 11, 1668–1675Publication Date (Print):November 1, 1990Publication History Pub…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectronic structure and conformation of polymers from cluster molecular orbital and molecular mechanics calculations: polyimideSherif A. Kafafi, John P. LaFemina, and Jeffrey L. NaussCite this: J. Am. Chem. Soc. 1990, 112, 24, 8742–8746Publication Date (Print):November 1, 1…
UNLABELLED: A varied-space grating mounted to both rotate and translate constitutes a practical single element fixed slit monochromator which is in focus at all wavelengths. KEYWORDS: Monochromators, diffraction gratings, grazing incidence, x-ray optics.
Abstract The belt-skim rubber of a passenger-car tire has changes in its tensile properties, M 100 and λ b , during service in the field. The changes are larger in higher temperature fields with an equivalent duration. It can be interpreted that the changes are caused simply by oxidative crosslinking similar to that w…
Abstract In the course of work on linear and ring polybutadienes with 62% 1,2 units, a number of discrepancies were noted with data on polybutadienes of various microstructure available in the literature. For example, G N ο =870 kPa for our 62% 1,2-polybutadiene. This is larger than G N ο =730 kPa for a 56% 1,2-polybu…