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San Jose State University

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Articles 631 - 648 of 648

Full-Text Articles in Physical Sciences and Mathematics

Measurement Of Synchrotron X-Ray Energies And Line Shapes Using Diffraction Markers, Juana Vivó Acrivos, S.S. P. Parkin, K. Hathaway, J. R. Reynolds, M. P. Klein, A. Thompson, D. Goodin Jan 1982

Measurement Of Synchrotron X-Ray Energies And Line Shapes Using Diffraction Markers, Juana Vivó Acrivos, S.S. P. Parkin, K. Hathaway, J. R. Reynolds, M. P. Klein, A. Thompson, D. Goodin

Faculty Publications, Chemistry

Standard reference markers for accurate, reproducible synchrotron x-ray energies are obtained using a three Si crystal spectrometer. The first two crystals are in the monochromator and the third is used to obtain diffraction markers which monitor the energy. Then for any value of the glancing angle on the reference Si crystal the energy for the (333) diffraction must occur at 3/4 that of the (444) and 3/5 of that for the (555). This establishes for the first time an absolute synchrotron energy scale. Higher-order diffractions are used to determine excitation line profiles. We conclude that the use of reference diffractions …

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Effects Of N2h4 On The Transition Temperature In The Anisotropic Superconductor Tase3, K. Yamaya, T. H. Geballe, Juana Vivó Acrivos, J. Code Jan 1981

Effects Of N2h4 On The Transition Temperature In The Anisotropic Superconductor Tase3, K. Yamaya, T. H. Geballe, Juana Vivó Acrivos, J. Code

Faculty Publications, Chemistry

No abstract provided.

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Conduction Band Symmetry In Ta Chalcogenides From Ta L Edge X-Ray Absorption Spectroscopy (Xas), Juana Vivó Acrivos, S.S. P. Parkin, J. Code, J. Reynolds, K. Hathaway, H. Kurasaki, E. Marseglia Jan 1981

Conduction Band Symmetry In Ta Chalcogenides From Ta L Edge X-Ray Absorption Spectroscopy (Xas), Juana Vivó Acrivos, S.S. P. Parkin, J. Code, J. Reynolds, K. Hathaway, H. Kurasaki, E. Marseglia

Faculty Publications, Chemistry

No abstract provided.

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Mott G-Ratios In Rbx(Nh3)1-X And Oxidation State Of Rubidium Compounds From Xas, Juana Vivó Acrivos, K. Hathaway, A. Robertson, M. P. Klein, A. Thompson Jan 1981

Mott G-Ratios In Rbx(Nh3)1-X And Oxidation State Of Rubidium Compounds From Xas, Juana Vivó Acrivos, K. Hathaway, A. Robertson, M. P. Klein, A. Thompson

Faculty Publications, Chemistry

The x-ray absorption spectra (XAS) of Rb metal, Rh,("JH,J, ,, 2H-NbSe2Rb111x and RbBr near the Rb K-edge have been used to ascertain that the oxidation state V of rubidium dissolved in ammonia and intt:rcalated in the layer compound is in the range 0 < V < I. Theobservededge shifts with temperature for semimctals are explainedin terms of the population of band states, and the ratio of the density states near the mobility edge over that calculated for a free electron model, i.e. the Mott ratio g, is ascertained using a semiempirical relation developed for the x-ray absorbance from Is levels to empty states ncar the mobility edge.

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Adaptative Alteration In Phospholipid Composition Of Plasma Membranes From A Somatic Cell Mutant Defective In The Regulation Of Cholesterol Biosynthesis, Michael Sinensky Jan 1980

Adaptative Alteration In Phospholipid Composition Of Plasma Membranes From A Somatic Cell Mutant Defective In The Regulation Of Cholesterol Biosynthesis, Michael Sinensky

Faculty Publications, Biological Sciences

A somatic cell mutant (CR1) of a Chinese hamster ovary cell (CHO-K1) which has previously been shown to be defective in the regulation of cholesterol biosynthesis accumulates more cholesterol than the parental cell line in plasma membranes. Although such an increase in membrane cholesterol should lead to an increase in the order parameter of these membranes, as measured with an electron spin resonance spin probe, the order parameters of mutant and wild-type plasma membranes are identical--apparently because of an adaptive alteration in membrane phospholipid composition. The phospholipid compositions of mutant and wild-type cell plasma membranes are compared and the mutant …

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In Situ Intercalation Of Tas2 In The Electron Microscope, G. Tatlock, Juana Acrivos Jan 1978

In Situ Intercalation Of Tas2 In The Electron Microscope, G. Tatlock, Juana Acrivos

Faculty Publications, Chemistry

Electron diffraction had been used to study the formation of a variety of complex superlattices in the 1T, 2H and 4Hb polytypes of TaS2 during intercalation with hydrazine gas (N2H4), in situ in the electron microscope. Results are presented over the temperature range 15K-360K and are interpreted in terms of scattering from periodic lattice distortions linked to charge density waves. Comparisons are also made with similar effects in both the as-grown crystals and the TaS2 samples containing other adducts.

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Properties Of Intercalated 2h-Nbse2, 4hb-Tas2 And 1t-Tas2, S. F. Meyer, R. E. Howard, G. R. Stewart, Juana Vivó Acrivos, T. H. Geballe Jan 1975

Properties Of Intercalated 2h-Nbse2, 4hb-Tas2 And 1t-Tas2, S. F. Meyer, R. E. Howard, G. R. Stewart, Juana Vivó Acrivos, T. H. Geballe

Faculty Publications, Chemistry

The layered compounds 2H-NbSe, 24Hb-TaS, 2and 1T-TaS2 have been intercalated with organic molecules; and the resulting crystal structure, heat capacity, conductivity, and superconductivity have been studied. The coordination in the disulfide layers was found to be unchanged in the product phase. Resistance minima appear and the superconducting transition temperature is reduced in the NbSe2 complex. Conversely, superconductivity is induced in the 4Hb-TaS2 complex. Corresponding evidence of a large change of the density of states, negative for 2H-NbSe2 and positive for 4Hb-TaS2, was also observed upon intercalation. The transport properties of all the intercalation complexes show a pronounced dependence upon the …

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Properties Of Hxtas2, D. W. Murphy, F. J. Disalvo, G. W. Hull, J. V. Waszczak, S. F. Meyers, G. R. Stewart, S. Early, Juana Vivó Acrivos, T. H. Geballe Jan 1975

Properties Of Hxtas2, D. W. Murphy, F. J. Disalvo, G. W. Hull, J. V. Waszczak, S. F. Meyers, G. R. Stewart, S. Early, Juana Vivó Acrivos, T. H. Geballe

Faculty Publications, Chemistry

The preparation of Hx TaS2 (0 < x < 0.87) is described. The compounds are only marginally stable at room temperature, slowly evolving H2S and H2 (and possibly Hp in air). Magnetic susceptibility data show that a low temperature transformation in 2H ... TaS2 (at so•K) is suppressed with the addition of hydrogen, and· at the same time the superconducting transition temperature T c rises from 0.8 to ~4.2•K at x = 0.11. Heat capacity measurements near this concentration show the superconductivity to be a bulk effect. Finally, by correlation of this data with susceptibility and T c measurements in other intercalation compounds, we suggest that the rise of T c (at low electron transfer) is due to suppression of the low temperature transformation and not due to an excitonic mechanism of superconductivity.

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Optical Studies Of Metal- Semiconductor Transmutations Produced By Intercalation, Juana Vivó Acrivos, Y. Liang, J. Wilson, A. Yoffe Jan 1971

Optical Studies Of Metal- Semiconductor Transmutations Produced By Intercalation, Juana Vivó Acrivos, Y. Liang, J. Wilson, A. Yoffe

Faculty Publications, Chemistry

Spectra of the alkali metal intercalation products of MoS2 and NbSc2 arc interpreted in terms of a previously published band model.

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Resonance Absorption Of P-Benzosemiquinone In The Zeeman Region, Juana Vivó Acrivos Jan 1967

Resonance Absorption Of P-Benzosemiquinone In The Zeeman Region, Juana Vivó Acrivos

Faculty Publications, Chemistry

No abstract provided.

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Spin-Resonance Transitions Of Free Radicals In The Zeeman Region, Juana Vivó Acrivos Jan 1966

Spin-Resonance Transitions Of Free Radicals In The Zeeman Region, Juana Vivó Acrivos

Faculty Publications, Chemistry

No abstract provided.

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Application Of The Sideband Technique To Wide-Line Nmr Spectra, Juana Vivó Acrivos Jan 1962

Application Of The Sideband Technique To Wide-Line Nmr Spectra, Juana Vivó Acrivos

Faculty Publications, Chemistry

No abstract provided.

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Hyperfine Splitting In Aromatic Free Radicals, Juana Acrivos Dec 1961

Hyperfine Splitting In Aromatic Free Radicals, Juana Acrivos

Faculty Publications, Chemistry

No abstract provided.

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Analysis Of The A3(X3)3 Nuclear Spin System And -Electron Coupled Hyperfine Splitting Constants In Aromatic Hydrocarbons, Juana Acrivos Jan 1961

Analysis Of The A3(X3)3 Nuclear Spin System And -Electron Coupled Hyperfine Splitting Constants In Aromatic Hydrocarbons, Juana Acrivos

Faculty Publications, Chemistry

The nuclear spin functions for the A3(X3)3 system have been developed and used to analyse the NMR spectra of (CH3)3C6H3 and (CF3)3C6H3. The π-electron coupled hyperfine splitting constants, obtained from the Ramsey theory with simple Hückel M.O.'s for benzene and without the assumption of an average energy of excitation for the virtual processes which give rise to the coupling, are in agreement with the hyperfine constants observed between the methyl groups and the ring protons in the above compounds.

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An Esr Study Of Stable Free Radicals In Natural And Synthetic Melanins, Juana Acrivos Sep 1958

An Esr Study Of Stable Free Radicals In Natural And Synthetic Melanins, Juana Acrivos

Faculty Publications, Chemistry

No abstract provided.

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Esr Of Impurities In Mgo, John Wertz, Juana Vivó, B. Musulin Jan 1955

Esr Of Impurities In Mgo, John Wertz, Juana Vivó, B. Musulin

Faculty Publications, Chemistry

SP1. Electron Spin Resonance of Impurities in Magnesium Oxide. John E. Wertz, Juana L. Vivo, and Boris Musulin, University of Minnesota.

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Study Of The Complex Products Of Polymerization Of Some Quinones By Esr Spectroscopy, Juana Acrivos, M Blois Jan 1955

Study Of The Complex Products Of Polymerization Of Some Quinones By Esr Spectroscopy, Juana Acrivos, M Blois

Faculty Publications, Chemistry

No abstract provided.

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Esr Of Defect Centers In Magnesium Oxide, John Wertz, Juana Acrivos Jan 1955

Esr Of Defect Centers In Magnesium Oxide, John Wertz, Juana Acrivos

Faculty Publications, Chemistry

B8. Electron Spin Resonance of Defect Centers in Magnesium Oxide.* John E. Wertz and Juana L. Vivo, University of Minnesota.

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