Materials Literature
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Separation of methylalumoxane (MAO) by adsorption on siliceous porous materials with different average pore diameters has been carried out; polymerization of ethylene was conducted with Cp2ZrCl2 using the separated MAO as cocatalyst, it was found that the MAO adsorbed on MCM-41 with average pore size of ca. 25 Å is ve…
Abstract New materials derived from metathesized soybean oil have been prepared and characterized. Thermal polymerization of metathesized soybean oil in the presence of air results in yellow, brittle gels. These materials display a curious tendency to produce audible popping sounds when exposed to chlorinated organic…
The “silica garden’', an amorphous aluminosilicate produced from a solution of sodium silicate seeded with crystalline aluminium nitrate, has been examined by FTIR, TGA, solid-state NMR and catalytic testing. The silica garden is a Brønsted acid catalyst and we characterize its porosity, acidity and catalytic activity…
Design and optimization of high-frequency magnetic components usually involve a number of tradeoffs between performance functions. This paper investigates the relationships between some of these factors by direct implementation of the thermal reference model previously presented by the authors. This unique thermal mod…
A method to estimate precise iron loss in an electrical machine is presented. This method implements a 2D finite element simulation of moving structure including the non-linear magnetic behaviour and a new dynamical hysteresis model of the magnetic circuit. The 2D finite element simulation is used to evaluate the indu…
Chiral nematic liquid crystal compositions containing mono- and di-acrylates in mixtures with non-reactive liquid crystal molecules were produced. Defect-free planar macroscopic alignment of the molecules was induced between uniaxially rubbed substrates. Polymerization of the acrylate groups was initiated photochemica…
This paper reviews some relevant citations regarding the non-specific forces that must be considered in oral bioadhesive events. These range from forces related to restorative dentistry to those related to prevention and molecular biology. Types of interactions discussed are: 1. Van der Waal's forces; 2. electrostatic…
Several new members (n = 2, 3, 4 members) of the family of layered perovskites Li2[AxBnO3n + 1] (A = Ca, Sr, La; B = Nb, Ta, Ti, Fe) have been synthesized for the first time. The structure analysis of Li2SrNb2O7 and Li2SrTa2O7 determined by powder X-ray diffraction (XRD), and of Li2La1.78Nb0.66Ti2.34O10 and Li2Sr2Nb3.…
Monolayers of the amphiphile 1-monopalmitoyl- rac -glycerol at the air−water interface assemble into domains in which the molecular tilt azimuth is organized into star-shaped patterns. When the domains are transferred to solid supports as Langmuir−Blodgett films, they are capable of producing a macroscopic azimuthal o…
In this paper a new iterative method is proposed for solving non-linear two point boundary value problems. The method is based on combining the well-known Newton iterative method and the Alternating Group Explicit (A.G.E.) method and is suitable for use on parallel computers.
Thin flakes of yttrium hydroxide coagulate in a manner similar to the houses of cards at an aging temperature lower than room temperature. Increasing the temperature results in an increase in the thickness of the flakes together with collapse of the structure of the house of cards. Relatively thick tablets of yttrium…
We propose a first principles computation of the thermodynamics of simple fragile glasses starting from the two-body interatomic potential. A replica formulation translates this problem into that of a gas of interacting molecules, each molecule being build of m atoms, and having a gyration radius (related to the cage…
Dielectric and Raman investigations in the temperature and frequency ranges 300–550K and 102 – 104Hz respectively show that M2(SO4). Te(OH)6 with (M = K, Rb and Cs) materials present three phase transition. The first transition observed at 480, 440 and 460K respectively for M = K, Rb and Cs and should be probably of o…
Liposomes have been used widely to improve the therapeutic activity of pharmaceutical agents. The traditional approach for such applications has been to formulate the pharmaceutical agent in liposomes prior to administration in vivo. In this report we demonstrate that liposomes exhibiting a transmembrane pH gradient i…
The reaction of tris-tetrahalogeno-o-benzosemiquinonate chromium(III) complexes, [CrIII(X4SQ)3] (X = Cl 1a or Br 1b), with bis(cyclopentadienyl) cobalt [CoIICp2], tetramethyltetraselenafulvalene (TMTSF) and tetrakis(methylsulfanyl)tetrathiafulvalene (TMT-TTF) afforded four charge-transfer compounds, [CoIIICp2][CrIII(X…
Biological polymers produced by microbial fermentation are naturally biodegradable and are potential environment-friendly substitutes for synthetic plastics. However, broader applications are restricted by high production costs. In this study, activated sludge bacteria in a conventional system treating a wastewater th…
Correlations in the atomic structure and dynamics extend in glasses and (supercooled) liquids to an intermediate range, which is a few times longer than the interatomic spacing. Motion on this length scale can be expected to be particularly revealing of collective phenomena. However, due to neutron scattering experime…
The synthesis of 2-methyl-1,4-bis[2-(4-propionyloxypropyloxyphenyl)ethenyl]benzene (1) and 2-methyl-1,4-bis[2-(4-acryloyloxypropyloxyphenyl)ethenyl]benzene (2) is reported. The liquid crystalline and photophysical behaviour has been investigated. Two liquid crystalline phases can be detected, with the lower temperatur…
The variational method for the calculation of the electronic polarizability of molecules within the NDDO-based semiempirical MO methods MNDO, AM1, and PM3 was parametrized to improve its accuracy. A training set of 156 compounds was used to fit 34 parameters simultaneously for 12 elements using a simplex optimization.…
The structure and dynamics of sodium disilicate are studied by molecular dynamics computer simulation. The structure is described by a partially destroyed tetrahedral SiO4 network and a spherical superstructure formed by the silicon and sodium atoms. The static structure factor of this simulation is in very good agree…