218 research outputs found
Mechanisms of Electrical Conductivity in Y(1-x)CaxBa2Cu3O6.1 System
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
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
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
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
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
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
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
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
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
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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