Materials Literature
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Abstract The radioactivity of Greek lignites and their ashes was studied. It was found that the radionuclides in them belong to the uranium series. Fly ashes are relatively rich in radioactivity. Concentrations up to 7 · 10 -5 g/g and 12 pCi/g were measured for 238 U and 226 Ra, respectively. The associated hazards fr…
Thermal degradation of aromatic polyesters (see text for formula) (m = 2, 3, 4, 5, and 6) was studied by pyrolysis/gas chromatography using a Curie-point pyrolyzer directly attached to a gas chromatograph with a thermally stable polar separation column (Thermon-1000) to cover a wide range of the degradation products.…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMolybdenum(IV)-porphyrin derivatives: the oxo(5,10,15,20-tetra-p-tolylporphyrinato)molybdenum(IV), MoO(TTP), and the dichloro(5,10,15,20-tetra-p-tolylporphyrinato)molybdenum(IV), Mo(Cl)21(TTP). Syntheses and structuresTharcis Diebold, Bernard Chevrier, and Raymond WeissCite…
Abstract The tensile mechanical properties of diethylenetriamine (DETA)‐cured bisphenol‐A‐diglycidyl ether (DGEBA) epoxies prepared from 9, 11 and 13 phr DETA are reported as a function of thermal history, strain‐rate and test temperature. These epoxies exhibit macroscopic yield stresses and >10% ultimate elongatio…
Abstract The title compounds can be synthesized by fusion reaction of the alkali carbonates with copper and sulfur at 790 °C. The structure was solved from X-ray diffractometer data of single crystals and refined to an R-value of 0.06. The compounds crystallize with the same layer-type structure which is closely relat…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXT3a-Hydroperoxypyrroloindole from tryptophan. Isolation and transformation to formylkynurenineMasako Nakagawa, Shiro Kato, Shigehiro Kataoka, and Tohru HinoCite this: J. Am. Chem. Soc. 1979, 101, 11, 3136–3137Publication Date (Print):May 1, 1979Publication History Published o…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSolid Solution Formation and Fractionation in Quasi-Binary Systems of Polyethylene FractionsPaul Smith and R. St. John ManleyCite this: Macromolecules 1979, 12, 3, 483–491Publication Date (Print):May 1, 1979Publication History Published online1 May 2002Published inissue 1 Ma…
Sternheimer shielding functions $\ensuremath{\gamma}(r)$ are derived by means of Sternheimer's procedure for a series of elements (Li, Na, K, Rb, F, Cl, Br, I, Cu, Fe, Ag, and Pr) with varying electronic configurations, with and without valence electrons, which are generally included in molecular-orbital calculations…
A computer simulation is described which allows the study of charge motion in thin polymer films of the type used for electret transducers. The simulation operates with a variety of possible boundary conditions and can include nonlinear transport terms as well as time-varying radiation-induced conductivity. Electron-i…
A series of technical data for the preparation of ferroelectric thin film PLZT by RF sputtering at substrate temperatures lower than 400°C with subsequent annealing is described. Films with dielectric and optical properties of considerable quality have been obtained under certain conditions. Parametric changes in the…
Abstract The aromatic polysulfone poly(oxy‐1,4‐phenylenesulfonyl‐1,4‐phenyleneoxy‐1,4‐phenyleneiso‐propylidene‐1,4‐phenylene) (I) showed no change in flexural yield strength after doses of γ‐radiation up to 600 Mrad in vacuum at 35,80, and 125°C ( T g = 190°C)). However, the flexural strength decreased markedly with d…
The authors present magnetisation measurements performed on a single crystal of TbCo 2 as well as spontaneous distortion studied by X-ray powder diffraction. At any temperature below T c (240K) the easy magnetisation direction is (111) while the most difficult is (100). A huge rhombohedral distortion appears below T c…
ZnO-Br2-O2, ZnCl2-O2, and ZnO-H2-H2O-O2 chemical-vapor-deposition (CVD) systems are studied to obtain as-grown optical waveguides of single-crystalline ZnO on sapphire. The waveguide is made on a very thin sputter-deposited epitaxial layer of ZnO on sapphire by using the ZnO-H2-H2O-O2 isothermal CVD system. The minimu…
Abstract Elastomeric networks made up of chain molecules of sufficient structural regularity generally exhibit strain‐induced crystallization. Crystallites thus formed have a pronounced reinforcing effect within the network, and thus increase its ultimate properties (ultimate strength and maximum extensibility), Incre…
Abstract The primary objective of the present study was to elucidate the relative contributions of exchangeable cations and surface forces to the swelling pressure, Π, of montmorillonite. To achieve this objective, measurements were made of the amount of water imbibed by Na‐saturated montmorillonites having different…
A model for high-spin?low-spin transitions in transition metal compounds is presented. The Jahn–Teller coupling between the d electrons and local distortion is considered as the driving force for the transition. The system built up of octahedrally coordinated Fe(II) complexes is studied microscopically on the basis of…
Further investigations, succeeding to the works of J. Phys. Soc. Japan 26 (1969) 631 and 29 (1970) 323, on the magnetic properties of Co(S x Se 1- x ) 2 in the whole concentration ranges (0≤ x ≤1) were performed by means of high magnetic field, electrical resistivity and low temperature X-ray diffraction measurements.…
The NADPH molecule binds to dihydrofolate reductase in an extended conformation. Several of the individual dihedral angles, especially in the adenine mononucleotide portion of the coenzyme, differ from their minimum energy conformations. The ribose phosphate portions of the coenzyme are involved in numerous specific h…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTInvestigation of the Structure of Acetylene-Terminated Polyimide Resins Using Magic-Angle Carbon-13 Nuclear Magnetic ResonanceM. D. Sefcik, E. O. Stejskal, R. A. McKay, and Jacob SchaeferCite this: Macromolecules 1979, 12, 3, 423–425Publication Date (Print):May 1, 1979Public…
Abstract Periodic feed switching between carbon monoxide/argon and oxygen/argon mixtures to a gradientless reactor has been found to significantly increase the average reaction rate as compared to the steady state rate, when the time averaged feed concentrations in both cases are stoichiometric. The rate enhancement a…