Materials Literature
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The usefulness of Crewe's Z-contrast technique for the study of small catalyst particles in the scanning transmission electron microscope is investigated and discussed. By forming suitable combinations of the annular dark-field and energy-loss signals, structural details in platinum particles as small as 2 nm may be i…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTExcluded-Volume Effects in Dilute Polymer Solutions. 7. Very High Molecular Weight Polystyrene in Benzene and CyclohexaneY. Miyaki, Y. Einaga, and H. FujitaCite this: Macromolecules 1978, 11, 6, 1180–1186Publication Date (Print):November 1, 1978Publication History Published…
The Judd-Ofelt (JO) theory was applied to optical-absorption transitions in Nd+3 : YVO4 to obtain intensity parameters (Ω2=5.88×10−20 cm2; Ω4=4.08×10−20 cm2; Ω6=5.11×10−20 cm2) and the radiative lifetime (152 μs) and quantum efficiency (0.72) of the 4F3/2 state. The variations of the absorptions with respect to the op…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMixed valence interactions in di-.mu.-oxo bridged manganese complexes. Electron paramagnetic resonance and magnetic susceptibility studiesStephen R. Cooper, G. Charles Dismukes, Melvin P. Klein, and Melvin CalvinCite this: J. Am. Chem. Soc. 1978, 100, 23, 7248–7252Publicatio…
Abstract High‐pressure CO 2 sorption data in semicrystalline poly(ethylene terephthalate) (PET) are presented for temperatures ranging from 25 to 115°C. The results are described by Henry's law above the glass‐transition temperature of PET, while a dual‐mode sorption model comprised of a Henry's law and a Langmuir iso…
A phase diagram for all the possible collinear spin arrangements for ${\mathrm{V}}_{2}$${\mathrm{O}}_{3}$ is derived within the atomic limit. Due to the fact that the ${a}_{1g}$ electrons of the V atoms form a diamagnetic bond for the vertical pairs of V atoms, the magnetic structure of ${\mathrm{V}}_{2}$${\mathrm{O}}…
An improved method of crystallographic structure refinement, especially suitable for large molecules, is described, it is based on simultaneous minimization of a realistic potential-energy function and a crystallographic residual. The method has already proved its worth in the final stages of refinement of two structu…
Although the problem of cellular proliferation may seem at first glance to be tremendously complex, the mechanisms which control it may be extremely simple. One of the primary factors which regulates the mitogenic response of a given cell type to a given class of mitogenic agents seems to be the cellular shape. We hav…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCompositional Variation of Glass-Transition Temperatures. 2. Application of the Thermodynamic Theory to Compatible Polymer BlendsP. R. CouchmanCite this: Macromolecules 1978, 11, 6, 1156–1161Publication Date (Print):November 1, 1978Publication History Published online1 May 2…
Abstract Deformation processes in viscoelastic polymers are examined in terms of an energy balance involving work, strain energy, viscous dissipation and damage. The concepts of time dependent damage and reversible cracks are presented. The latter, while giving rise to novel mechanical behavior in viscoelastic materia…
Abstract A method is given for the determination of Clebsch‐Gordan coefficients of finite groups. The Clebsch‐Gordan coefficients may be arranged into vectors which are eigenvectors of certain projection matrices. It is shown how an appropriate set of orthonormal eigenvectors of these matrices may be obtained; this se…
Grain size‐microcracking trends are examined in the three pseudobrookite oxides MgTi 2 O 5 , Fe 2 TiO 5 , and Al 2 TiO 5 . These trends are toward smaller critical grain sizes, lower elastic moduli, and lower strengths with increased thermal expansion anisotropy. Extension of an energy criterion relates the micro‐crac…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStudy of metal oxide catalysts by temperature programmed desorption. 4. Oxygen adsorption on various metal oxidesMasakazu Iwamoto, Yukihiro Yoda, Noboru Yamazoe, and Tetsuro SeiyamaCite this: J. Phys. Chem. 1978, 82, 24, 2564–2570Publication Date (Print):November 1, 1978Publ…
Raman spectra of FeO, Fe 3 O 4 , α-Fe 2 O 3 , α-FeOOH, and γ-FeOOH, the common products of iron oxidation, have been measured. The spectra of FeO and Fe 3 O 4 appear to be identical. Armco iron oxidized in air at 250°C was examined by Raman spectroscopy after varying periods of exposure and the surface film was found…
Greatly enhanced Raman scattering from monolayers of pyridine adsorbed on silver has been reported by several authors. I propose that the anomalous intensity arises from preresonant or resonant excitations of conduction electron resonances in adsorbate covered metal bumps on the surface. The bumps form a two-dimension…
X-ray data on silicon, tetracyanoethylene, p -nitropyridine N -oxide and ammonium thiocyanate are refined with a generalized aspherical-atom formalism as introduced by Stewart, but modified to have a spherical valence more similar to the unperturbed HF valence shell. Several types of radial dependences of the multipol…
The crystal structure of NbSe 3 has been refined from single crystal X-ray diffraction data. It has a monoclinic symmetry with lattice parameters: a=10.009 AA, b=3.4805 AA, c=15.629 AA, beta =109.47 AA, space group P2 1 /m and six formulae per unit cell. The crystal structure of NbSe 3 as determined at 100K shows that…
Abstract La polymérisation de I'acttoxy‐2 styrène, du parachloro acétoxy‐2 styrène, du paramb thyl acétoxy‐2 styrène et du paranitro acetoxy‐2 styrène a été obtenue avec des amorceurs radicalaires ou par voie thermique. Les polymtres obtenus possedent des masses moyennes en nombre atteignant 200000. L'étude du comport…
Abstract It has been studied the intrinsic viscosity ratios of cellulose solutions in different solvents and of the corresponding nitrates dissolved in aceton using cellulose samples from different origins and with different degrees of polymerization. The results demonstrate that with FeTNa and CdEn as solvents, molec…
The adsorption of nitric oxide and its dissociation on the Ru(001) surface have been studied through the vibrational energies of the adsorbed layer. The inelastic electron scattering measurements show that two distinct states of molecular NO are adsorbed at 130 K. The dissociation of a bridged NO is complete at 316 K,…