Materials Literature
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Neutron diffraction studies have been made of ice nucleation in various forms of porous sol−gel silicas and ordered aluminosilicates. It is shown that the crystal structure of the ice exhibits significant variation according to the conditions and often has a diffraction pattern composed of a hybrid with both cubic and…
Molecular dynamics simulations of calcium silicate (CaSiO 3 )intergranular films that were formed during the liquid‐phase sintering of alumina (Al 2 O 3 )ceramics were conducted. A constant‐pressure algorithm was used in the simulations to accommodate changes in the sample size during heat treatment and tensile tests.…
The phenomenon of photoinduced molecular reorientation of absorbing nematic liquid crystals is analyzed in a macroscopic general framework and with a specific molecular model. The photoinduced torque responsible for the reorientation is shown to describe a transfer of angular momentum from the molecule center-of-mass…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTStructural Distortion in Five-Coordinate Nitrosyl Iron Porphyrins. Axial Ligand Tilting and Its Effect on Equatorial GeometryMary K. Ellison and W. Robert ScheidtView Author Information The Department of Chemistry and Biochemistry University of Notre Dame, Notre Dame,…
The scanning electrochemical microscope (SECM) is used to generate localized corrosion at passivating iron surfaces by using the tip to generate ions. Use of the SECM allows the rapid establishment of a locally aggressive chemical environment at a preselected site on the iron surface. The susceptibility for passive la…
The melting behavior of isothermally crystallized PET has been studied using linear heating in a differential scanning calorimeter (DSC). Variables such as crystallization temperature, crystallization time, heating rate, and average molecular weight are the main focus of the study. On the basis of several experimental…
We used molecular dynamics (MD) techniques to examine the encapsulation of Bengal Rose (BR) molecules in the Meijer dendrimer box (DBox) formed by the addition of tert -butyloxycarbonyl- l -Phe (tBOC- l -Phe) cap molecules to the 64 terminal primary amines of a fifth generation poly(propyleneimine) (PPI-5) dendrimer.…
The facile and clean synthesis of a novel class of highly solvatochromic chromophores 1 is reported. Compounds 1 are push−pull systems containing a negatively charged dicyanomethanide as a donor group and a positively charged N -alkylpyridinium as an acceptor group. The terminal polar functions are spaced by a thiophe…
Other| August 01, 1997 All-atom ab initio energy minimization of the kaolinite crystal structure J. David Hobbs; J. David Hobbs Sandia National Laboratories, Computational Material Sciences Department, Albuquerque, NM, United States Search for other works by this author on: GSW Google Scholar Randall T. Cygan; Randall…
The complexes [Cu 8 (dpk·OH) 8 (O 2 CMe) 4 ](ClO 4 ) 4 ·9H 2 O ( 1 ) and [Cu(dpk·H 2 O) 2 ](O 2 CMe)(ClO 4 )·2H 2 O ( 2 ), where dpk·H 2 O is the hydrated, gem -diol form of di-2-pyridyl ketone, have been prepared. Complex 1 crystallizes in triclinic space group P 1̄ with the following unit cell dimensions at 25 °C: a…
A series of dicopper(II) complexes with two tetradentate (N 4 ) diazine ligands (PAHAP ( 1 ), PMHAP ( 2 )) is reported, in which the two d x 2 - z 2 type copper centers are bridged by a single N−N bond. Varying the coligands leads to a situation where the angle between the copper planes can be varied. For small angles…
Insect cells coinfected with a baculovirus coding for the proalpha1(I) chain of human type I procollagen and a double promoter virus coding for the alpha and beta subunits of human prolyl 4-hydroxylase produced homotrimeric [proalpha1(I)]3 procollagen molecules. The use of an additional virus coding for the proalpha2(…
A new low-pressure flow reactor operated as a Knudsen cell and intended for chemical kinetic studies is described. The reactor is specifically designed to study the kinetics of heterogeneous reactions. Gas-phase species are detected either by mass-spectrometric sampling or by in situ optical techniques, e.g., laser-in…
A new electroluminescent polyester based on an electrochemically stable polypyridylruthenium(II) complex was prepared by the step-growth polymerization method. The versatility of changing its solubility by changing counteranions makes it possible to prepare thin-film devices by either spin-coating or the self-assembly…
The new pure silica polymorph ITQ-4, structure code IFR, Si32O64, monoclinic I2/m a = 18.65243(13), b = 13.49597(8), c = 7.63109(6) Å, β = 101.9781(5)°, is a zeolitic material containing a large sinusoidal channel with 12-member ring windows as minimum apertures. Its void volume (0.21 cm3/g) is surpassed only by that…
The dynamics of diglycidyl ether of bisphenol-A (DGEBA) was studied by employing broadband dielectric spectroscopy over a wide temperature range extending from below to above the glass-transition temperature. Dielectric spectra reveal the existence of two relaxation processes: the structural relaxation, slowing down f…
The characteristic sizes of perovskite ferroelectrics have been examined by mean-field theory in a three dimensional base, leading to a detailed evaluation of the ultimate limits of physical sizes in nanostructured ferroelectrics with the stable polar phase in situations where the influence of depolarizing field can b…
The irreversible electro-optical response (memory effect) of 'liquid crystal-aerosil' suspensions under the influence of an electric field is investigated. Thereby, the influence of the aerosil concentration on the efficiency of the memory effect is studied. The experimental results are discussed in the frame of a mod…
The curing of unsaturated polyesters in the presence of organic and inorganic fillers was studied by rheology and differential scanning calorimetry (DSC). A commercial resin was used as unsaturated polyester and pressed olive stones, which are an agricultural by-product, talc and quartz in different concentrations wer…
Evolved gas analysis−Fourier transform infrared spectroscopy was used to investigate the pyrolysis of tris(2,4-pentanedionato)aluminum on glass surfaces between 500 and 900 K in vacuum and in low-pressure water vapor atmospheres. Pyrolysis of tris(2,4-pentanedionato)aluminum in vacuum produced Al 2 O 3, carbon, water…