218 research outputs found

    Mechanisms of Electrical Conductivity in Y(1-x)CaxBa2Cu3O6.1 System

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    Systematic studies of transport properties in deoxygenated Y(1-x)CaxBa2Cu3O6.1 series allowed to propose a diagram of conductivity mechanisms for this system. At intermediate temperature a variable range hopping (VRH) in 2 dimensions prevails. At lower temperature VRH in the presence of a Coulomb gap for smaller x and VRH in 2 dimensions for larger x are found. In a vicinity of superconductivity we observe conductivity proportional to \sqrt{T}. Thermally activated conductivity dominates at higher temperature. This diagram may be universal for the whole family of undoped high Tc related cuprates.Comment: 5 page

    Electronic structure and transport properties of CeNi9In2

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    We investigated CeNi9In2 compound, which has been considered as a mixed valence (MV) system. Electrical resistivity vs. temperature variation was analysed in terms of the model proposed by Freimuth for systems with unstable 4f shell. At low temperature the resistivity dependence is consistent with a Fermi liquid state with a contribution characteristic of electron-phonon interaction. Ultraviolet photoemission spectroscopy (UPS) studies of the valence band did not reveal a Kondo peak down to 14 K. A difference of the spectra obtained with photon energies of low and high photoionization cross sections for Ce 4f electrons indicated that 4f states are located mainly close to the Fermi energy. The peaks related to f_{5/2}^1 and f_{7/2}^1 final states cannot be resolved but form a plateau between -0.3 eV and the Fermi energy. X-ray photoemission spectroscopy (XPS) studies were realized for the cerium 3d level. The analysis of XPS spectra within the Gunnarsson-Sh\"onhammer theory yielded a hybridization parameter of 104 meV and non-integer f level occupation, being close to 3. Calculations of partial densities of states were realized by a full potential local orbital (FPLO) method. They confirm that the valence band is dominated by Ni 3d states and are in general agreement with the experiment except for the behavior of f-electrons.Comment: 10 pages, 5 figure

    Health Concerns of Adolescents and Adults with Spina Bifida

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    The Transitional and Lifelong Care (TLC) program is a multidisciplinary clinical service providing comprehensive, coordinated care to adolescents and adults with spina bifida (SB). This study sought to identify the most common health concerns among this population at initial consultation and identify patient factors related to these concerns to ultimately improve health care delivery. A retrospective chart review was performed. Descriptive analyses were completed and associations between concerns and patient factors were determined using Spearman’s rho correlation coefficients. A multiple linear regression was performed to estimate the relationship between patient factors and total number of concerns reported. Ninety-four patient charts were reviewed (Mean age=29.04 ± 13.8 years). On average, patients reported 9 health concerns with care coordination being the most prevalent concern. Patient factors were not related to specific or total number of health concerns. Individualized, coordinated care and a medical home are warranted for adults with SB

    Evidence of momentum dependent hybridization in Ce2Co0.8Si3.2

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    We studied the electronic structure of the Kondo lattice system Ce2Co0.8Si3.2 by angle-resolved photoemission spectroscopy (ARPES). The spectra obtained below the coherence temperature consist of a Kondo resonance, its spin-orbit partner and a number of dispersing bands. The quasiparticle weight related to the Kondo peak depends strongly on Fermi vectors associated with bulk bands. This indicates a highly anisotropic hybridization between conduction band and 4f electrons - V_{cf} in Ce2Co0.8Si3.2.Comment: 6 page

    Electronic structure of TmPdIn

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    Electronic structure of a ternary TmPdIn compound, which crystallizes in the hexagonal ZrNiAl-type structure, was studied by X-ray photoemission spectroscopy and ultraviolet photoemission spectroscopy. Density of states in the valence band was calculated by means of the augmented plane wave/local orbital method based on density functional theory. The results showed that the valence band is formed mainly of Tm 4f and Pd 4d states. In the ultraviolet photoemission spectra one can distinguish Pd 4d maximum and Tm 4f multiplet peaks, which are displaced with respect to those of pure Tm

    FTIR spectroscopy of water glass - the binder moulding modified by ZnO nanoparticles

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    The subject of the paper is the determination of the infl uence of the colloidal nanoparticles of zinc oxide on the structure of sodium water glass. Nanoparticles of zinc oxide in ethanol solvent were introduced into the water glass. The modification and structural changes were determined by means of the FT-IR absorption spectra. In order to determine the kind of infl uence: binder-modifier the spectroscopic FTIR analysis of samples of a fresh binder and of a binder hardened for 24 h in the air was performed by means of the spectrometer Digilab Excalibur with a standard DTGS detector

    FTIR spectroscopy of water glass - the binder moulding modified by ZnO nanoparticles

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    The subject of the paper is the determination of the infl uence of the colloidal nanoparticles of zinc oxide on the structure of sodium water glass. Nanoparticles of zinc oxide in ethanol solvent were introduced into the water glass. The modification and structural changes were determined by means of the FT-IR absorption spectra. In order to determine the kind of infl uence: binder-modifier the spectroscopic FTIR analysis of samples of a fresh binder and of a binder hardened for 24 h in the air was performed by means of the spectrometer Digilab Excalibur with a standard DTGS detector

    Cohesion and adhesion properties of modified water glass with colloidal solutions of ZnO

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    The article discusses the issue of the influence of colloidal solutions of nanoparticles of ZnO obtained using original method on physical and chemical properties (cohesions, adhesion, wettability) of water glass. Adhesion and cohesion strength has been determined on the basis of own methodology of measurement using a special apparatus. The results of the above measurements have been supplemented with selected measurements of quartz wettability by the modified binder. Also, exemplary results have been presented of tests involving basic properties of moulding sans containing an addition of the aforementioned binder. In conclusions, the influence of binder modification on the properties of moulding sands have been presented

    Cohesion and adhesion properties of modified water glass with colloidal solutions of ZnO

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    The article discusses the issue of the influence of colloidal solutions of nanoparticles of ZnO obtained using original method on physical and chemical properties (cohesions, adhesion, wettability) of water glass. Adhesion and cohesion strength has been determined on the basis of own methodology of measurement using a special apparatus. The results of the above measurements have been supplemented with selected measurements of quartz wettability by the modified binder. Also, exemplary results have been presented of tests involving basic properties of moulding sans containing an addition of the aforementioned binder. In conclusions, the influence of binder modification on the properties of moulding sands have been presented

    Generalized Spectral Signatures of Electron Fractionalization in Quasi-One and -Two Dimensional Molybdenum Bronzes and Superconducting Cuprates

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    We establish the quasi-one-dimensional Li purple bronze as a photoemission paradigm of Luttinger liquid behavior. We also show that generalized signatures of electron fractionalization are present in the angle resolved photoemission spectra for quasi-two-dimensional purple bronzes and certain cuprates. An important component of our analysis for the quasi-two-dimensional systems is the proposal of a ``melted holon'' scenario for the k-independent background that accompanies but does not interact with the peaks that disperse to define the Fermi surface.Comment: 7 pages, 8 figure
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