Materials Literature
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We study spin-dependent interband resonant tunneling in double-barrier InAs/AlSb/ GaMnSb heterostructures. We demonstrate that these structures can be used as spin filters utilizing spin-selective tunneling of electrons through the light-hole resonant channel. High densities of the spin polarized electrons injected in…
Surface effects on the electronic energy loss of charged particles entering a metal surface are investigated within linear-response theory, in the framework of time-dependent density functional theory. Interesting phenomena occur in the loss spectra originated by the boundary (bregenzung) effect, which is as a consequ…
A discrete model for the sintering of polydisperse, inhomogeneous arrays of cylinders is presented with empirical contact force-laws, taking into account plastic deformations, cohesion, temperature dependence (melting), and long-time effects. Samples are prepared under constant isotropic load, and are sintered for dif…
We report temperature and field dependent measurements of the magnetic susceptibility, specific heat and resistivity of sintered YbB2 pellets, prepared via two distinct reaction routes, utilizing different temperatures, pressures and sintering times. Sample behavior is affected by the preparation procedure, as a conse…
In this paper, a recently developed analytical equation of state (EOS) is used to investigate the bulk modulus of compressed liquid cesium and to locate common compression factor and the bulk modulus quiescence point(s). This EOS is applied quick well to Na and Rb far from Tc. Bulk modulus of liquid cesium have two qu…
Attractive alternatives to conventional contrast agents for magnetic resonance imaging applications are the paramagnetic chemical exchange saturation transfer (CEST) agents based on saturation transfer (ST) to the solvent water resonance. The ratio of ST effects obtained upon irradiating Ln-coordinated water and amide…
A simple and efficient concept has been developed for the synthesis of pH-responsive molecular nanocarriers based on commercially available hyperbranched polymers. These dendritic core-shell architectures can encapsulate, transport, and selectively release polar guest molecules in an acidic environment (pH 3–6, see sc…
The thermodynamic properties and the morphology of syndiotactic polystyrene solid samples exposed to solvents (benzene and toluene) are investigated. It is shown that, as far as the melting properties are concerned, there is no significant difference between these samples and solution-cast samples. This suggests that…
The photoluminescence efficiency of InP nanocrystals prepared via the dehalosilylation reaction between indium chloride and tris-(trimethylsilyl)phosphine in mixtures of trioctylphosphine and trioctylphosphine oxide can be drastically improved by etching with fluorine compounds, as proposed several years ago by Micic…
We present density-functional theory for linear and nonlinear response functions using an explicit exponential parametrization of the density operator. The response functions are derived using two alternative variation principles, namely, the Ehrenfest principle and the quasienergy principle, giving different but nume…
We investigate the optical properties of spherical gold and silver clusters with diameters of 20 nm and larger. The light scattering spectra of individual clusters are measured using dark-field microscopy, thus avoiding inhomogeneous broadening effects. The dipolar plasmon resonances of the clusters are found to have…
X-ray photoelectron spectroscopy (XPS) investigations of supported nanoparticles smaller than 10 nm show a significant shift of the electron binding energy of core levels compared with the bulk values. In this work, such shifts were examined at differently supported and prepared gold nanoparticles for the 4f electron…
A major challenge to increasing bandwidth in optical telecommunications is to encode electronic signals onto a lightwave carrier by modulating the light up to very fast rates. Polymer electro-optic materials have the necessary properties to function in photonic devices beyond the 40-GHz bandwidth currently available.…
We report on the high-temperature ferromagnetism in Co-doped ZnO films fabricated by the sol–gel method above 350 K. The lattice constant of c axis of wurtzite Zn1−xCoxO follows Vergard’s law for 0<x<0.25. For Zn1−xCoxO with x⩾0.25, a secondary phase is detected. The Zn1−xCoxO exhibits ferromagnetic beha…
Despite being first demonstrated over 160 years ago, and offering significant environmental benefits and high electrical efficiency, it is only in the last two decades that fuel cells have offered a realistic prospect of being commercially viable. The solid oxide fuel cell (SOFC) offers great promise and is presently…
The scope of this paper is to present some aspects in modeling of electrical field in high-voltage direct-current (HVDC) cables. Some computation models for electrical fields are presented. Computation procedures are developed for DC cables with one and two imperfect dielectric insulation layers for capacitive and res…
While measuring the resistive losses in transformer windings, a great difference between the measurement results of additional losses was noticed due to the skin-effect at the transformer without box and the theoretical calculated results. In order to find the reason for the phenomenon, measurements of resistive losse…
AC dissipation current waveforms of polyethylene and polypropylene films show nonlinear distortion in AC high-field region. This non-linearity was supposed to be related to the behavior of AC space charge formation in the sample. However, the measurement of AC space charge distribution is not so easy due to the resolu…
For the polymeric insulating materials such as polypropylene (PP) and low density polyethylene (LDPE), the surface oxidization and chain scission that deteriorate the insulation performance are induced by the irradiation of the ultraviolet photons. Photochemical reactions are responsible for such oxidization and bond…
In this paper, we have investigated the trapping parameters in the surface layer of two kinds of insulating materials. The final aim is to construct the relationship between the surface microstructure of an insulating material and its flashover phenomena.