Materials Literature
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The electrical properties of CaCu 3 Ti 4 O 12 ceramic materials, showing an enormously large dielectric constant, were investigated. It was found that the grain boundary plays an important role in the giant dielectric behaviour of these ceramics. Measurement of the electrical current density ( J ) versus the electrica…
We have developed a theory of exciton-polariton band structure of resonant three-dimensional photonic crystals for arbitrary dielectric contrast and effective mass of the exciton that is excited in one of the compositional materials. The calculation has been carried out for a periodic array of spheres embedded in a di…
We report the low-temperature multi-frequency ESR studies of copper pyrimidine dinitrate, a spin-1/2 antiferromagnetic chain with alternating $g$-tensor and the Dzyaloshinskii-Moriya interaction, allowing us to test a new theoretical concept proposed recently by Oshikawa and Affleck [Phys. Rev. Lett. 82, 5136 (1999)].…
Magnetic nanoparticles can be used for a variety of biomedical applications. They can be used in the targeted delivery of therapeutic agents in vivo , in the hyperthermic treatment of cancers, in magnetic resonance (MR) imaging as contrast agents and in the biomagnetic separations of biomolecules. In this study, a cha…
We use the Surface Green Function Matching (SGFM) method and a tight-binding hamiltonian to calculate the (100)-surface electronic band structure and local density of states of the series of Cu-based A^{I}B^{III}C2^{VI} chalcopyrites . We find four surface states in the optical gap energy region of s-p character and t…
Small but influential: Chirality transfer from a small chiral organic unit (D- or L-tartrate) to a very large metal–oxide framework is demonstrated by the enantiomerically pure, nonracemizing polytungstates d- or L-1 (see picture, the central part is shown in polyhedral form; purple Zr, gray W, blue P, black C, red O)…
Magnetic-field-induced electric polarization in nanostructured multiferroic composite films was studied by using the Green's function approach. The calculations showed that large magnetic-field-induced polarization could be produced in multiferroic nanostructures due to enhanced elastic coupling interaction. Especiall…
The luminescence properties of Eu 2+ -activated alkaline-earth silicon-oxynitrides have been studied. In the BaO−SiO 2 −Si 3 N 4 system, a new BaSi 2 O 2 N 2 compound was obtained having the monoclinic structure with lattice parameters a = 14.070(4) Å, b = 7.276(2) Å, c = 13.181(3) Å, β = 107.74(6)°. All MSi 2 O 2 - δ…
The recent literature concerning the magnetocaloric effect (MCE) has been reviewed. The MCE properties have been compiled and correlations have been made comparing the behaviours of the different families of magnetic materials which exhibit large or unusual MCE values. These families include: the lanthanide (R) Laves…
The odd-even effect is demonstrated, for the first time, in dilute polymeric solutions of polyethers, consisting of substituted luminescent quinquephenyl units which are connected by flexible aliphatic chains of 7-12 methylene groups. The effect, which is demonstrated by means of steady state and time resolved fluores…
Natural convection plays an important role in determining the thermal load from molten core accumulated in the reactor vessel lower head during a severe accident. Several numerical and experimental programs were conducted to study the heat transfer in the molten pool. Previous investigations were mostly related to the…
Abstract Poly(vinyl chloride) (PVC) resin was modified by grafting the non‐ionic surfactant poly(oxyethylene 20 sorbitan) monolaurate (Tween ® 20) using isocyanate chemistry. PVC was aminated using ethylenediamine and coupled with hexamethylene diisocyanate. Tween 20 was then reacted with the polymer, resulting in the…
PURPOSE: To determine whether tissue edema changes gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA)-enhanced T1 relaxation times of the viable myocardium. MATERIALS AND METHODS: A total of 16 isolated pig hearts were divided into four groups (N=4/group) and perfused in a Langendorff apparatus. Gd-DTPA was inje…
The phenomenon of the Portevin-LeChatelier effect is described on the basis of a constitutive model of dynamic strain ageing, which was implemented in three-dimensional finite element analysis. The simulation of the deformation behaviour of Al–Cu alloys is performed, using the constitutive parameters as required by th…
Abstract A series of poly(trimethylenecarbonate‐ε‐caprolactone)‐block‐poly( p‐ dioxanone) copolymers were prepared with varying feed rations by using two step polymerization reactions. Poly(trimethylenecarbonate)(ε‐caprolactone) random copolymer was synthesized with stannous‐2‐ethylhexanoate and followed by adding p‐…
Temperature behaviors of X-ray luminescence (XL), photoluminescence (PL), photostimulated luminescence, and thermoluminescence (TL) were studied in BaFCl:Eu2+ single crystals from room temperature to liquid nitrogen temperature. Six emissions at 275, 315, 365, 385, 435, and 500 nm were observed in the XL spectra and a…
Abstract A 1‐D model for methane partial oxidation in a tubular microreactor is considered. This work is motivated by a recent report by Kikas et al. that experimentally demonstrated the possibility of autothermal generation of hydrogen by partial oxidation of methane in a tubular microreactor. The reactor consists of…
We present a theoretical investigation of energy transfer in the phenylene ethynelene dendrimer known as the nanostar. Data from extensive molecular dynamics simulations are used to model the dynamical effects caused by torsional motion of the phenyl groups. We compare rate constants for energy transfer between the tw…
Abstract Nickel–chromium ferrites NiCr x Fe 2– x O 4 (0 ≤ x ≤ 1.4) were studied using X‐ray diffraction, magnetization measurements and Mössbauer spectroscopy. X‐ray diffraction patterns show that all samples have cubic spinel structure. The temperature dependent magnetic measurements revealed that a magnetic compensa…
We report the global minima for aluminium, gold and platinum metal clusters modelled by the Voter–Chen version of the embedded-atom model potential containing up to 80 atoms using the basin-hopping Monte Carlo minimization approach. The results show that the global minima of the Al, Au and Pt clusters have structures…