Materials Literature
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We reconsider a number of measurements for the overall hydration kinetics of tricalcium silicate pastes having an initial water to cement weight ratio close to 0.5. We find that the time dependent ratio of hydrated and unhydrated silica mole numbers can be well characterized by two power-laws in time, $x/(1-x)\sim (t/…
The strain induced by lattice mismatch at the interface is responsible for the different value of the band discontinuities observed recently for the AlN/GaN (AlN on GaN) and the GaN/AlN (GaN on AlN) polar (0001) interface. We present a first-principles calculation of valence band offsets, interface dipoles, strain-ind…
There exists a generic relationship between the thermodynamics of a continuous polymer with a generic self-interaction and the two-point function of an interacting field-theory. In addition, the (2N)-point function of the resulting field theory is similarly related to a system of N interacting polymers. In the present…
A continuum model derived from an atomistic Hamiltonian is used to examine the ordering kinetics in CuAu. A detailed description of the formation of the low and high temperature ordered and modulated superlattice states is given. The metastability of the modulated phase at low temperatures is shown to severely hinder…
I consider the effects of polymers on the smectic phase of a host liquid-crystal matrix. Focusing on the regime in which the polymers are predominatly confined between the smectic layers, I find that the presence of the polymers can lead to a re-entrant phase diagram with the smectic-C sandwiching the smectic-A phase…
A novel intramolecular allylic migration from silicon to carbon was observed during the reaction of allylmethyldichlorosilane with tropolone in the presence of triethylamine to give an isomeric mixture of pentacoordinate silicon compounds having allylated tropolonato ligand. The molecular structure of the major isomer…
An oblate rhombohedral unit cell of α-boron crystal was constructed and the transition of two icosahedra lying at the ends of its short body diagonal was simulated. By applying ab initio Hartree-Fock self-consistent field methods different configurations of two icosahedra were investigated. The obtained structure B 24…
Quasicrystals are solids with quasiperiodic atomic structures and symmetries forbidden to ordinary periodic crystals-e.g., 5-fold symmetry axes. A powerful model for understanding their structure and properties has been the two-dimensional Penrose tiling. Recently discovered properties of Penrose tilings suggest a sim…
New ferrocenyl dendritic macromolecules based on flexible poly(propylenimine) dendrimer cores, built up to the fifth generation, containing 4, 8, 16, 32, and 64 peripheral ferrocenyl moieties, have been prepared and characterized. Solution electrochemical studies showed that all the ferrocenyl redox centers attached t…
To demonstrate that crystallographic methods can be applied to index and interpret diffraction patterns from well-ordered quasicrystals that display non-crystallographic 5-fold symmetry, we have characterized the properties of a series of periodic two-dimensional lattices built from pentagons, called Fibonacci pentili…
We study the approach to global breakdown in disordered media driven by increasing external forces. We first analyze the problem by mean-field theory, showing that the failure process can be described as a first-order phase transition, similarly to the case of thermally activated fracture in homogeneous media. Then we…
We study the behavior of fracture in disordered systems close to the breakdown point. We simulate numerically both scalar (resistor network) and vectorial (spring network) models with threshold disorder, driven at constant current and stress rate respectively. We analyze the scaling of the susceptibility and the clust…
It has been recently observed that synthetic materials subjected to an external elastic stress give rise to scaling phenomena in the acoustic emission signal. Motivated by this experimental finding we develop a mesoscopic model in order to clarify the nature of this phenomenon. We model the synthetic material by an ar…
We present an exact calculation to show that an infinite Sierpinski gasket fractal supports an infinite number of extended electron states. We work within the real space renormalization group (RSRG) scheme and show that by analysing the recursion relations for the Hamiltonian parameters one can extract the eigenvalues…
Br K-edge EXAFS spectra of solid and liquid KBr have been performed and analysed using advanced techniques for data analysis (GNXAS). Structural results on solid KBr at room temperature and near melting are compared with molecular dynamics (MD) simulations and diffraction data. The first-neighbour distribution is foun…
The structure, phase transformation and magnetic properties of mechanically alloyed (MA) alloys and have been studied systematically. The compound can be formed within a wide window for the range of composition and annealing temperature. More carbon than the stoichiometric content for is necessary to stabilize the tet…
Low-sulfate seawater (LSSW) technology provides operational and economic benefits for desulfating seawater to control barium sulfate (BaSO{sub 4}) and strontium sulfate (SrSO{sub 4}) scale. This concluding article in a three part series describes, from a scale control perspective, the membrane technology deployed in t…
This Letter describes neutron diffraction measurements of the rocksalt structured phase of AgI at high pressure and temperature and the structural disorder which accompanies its high conductivity. In contrast to the first-order structural phase transition which results in fast-ionic $\ensuremath{\alpha}$-AgI at ambien…
Measurements of isothermal ( ), high-pressure behaviour (up to 270 MPa) of complex electric permittivity in supercooled glycerol are presented. The observed peaks of relaxation in absorption curves show increasing relaxation time with increasing pressure. The behaviour of can be reproduced by the pressure version of a…
The vibrations of boron carbide have been studied by the valence force model. There have been so far several ambiguities in the interpretation of experimental spectra, which made theoretical study difficult. This paper solves the main difficulties, that is, characterization of the highest band and most of the Raman ba…