Materials Literature
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The lacunary α2-[As2W17O61]10− derived from the Dawson molecule α-[As2W18O62]6− was used as a ligand for the following metal cations: Mn2+, Fe3+, Co2+, Ni2+, Cu2+ and Zn2+. The cyclic voltammograms of this lacunary precursor species, as well as those of the substituted complexes were run in a medium at pH = 3. A syste…
(CdO)y(ZnO)1–y thin films have been prepared by the sol–gel process, based on precursor solutions used separately for such oxides. The Cd/(Cd + Zn) atomic ratio in solution ranged from 0 to 0.32. These compositions were selected on the basis of an observed abrupt fall, of ca. four orders of magnitude, in the resistivi…
Nanostructured MnFe2O4 particles in the size range 7–30 nm are prepared by the thermal decomposition of manganese iron citrate precursor at different temperatures (623–973 K) in an inert atmosphere. The Curie temperature (TC) of the as-prepared MnFe2O4 nanosized particles is found to be higher than the bulk material b…
The effective thermal conductivity of single and multilayer AlN/diamond composite films deposited on silicon substrate with a planar interface is determined experimentally. As a result of the small thickness and the good crystalline quality of the AlN and diamond films, the contribution to the effective thermal resist…
Abstract The crystal structures of two K 1- x Cs x BSi 2 O 6 solid solutions have been refined at room temperature by the Rietveld method: x = 0.12, a = 12.6858(4) Å, R wp = 7.66%, R F = 5.56% and x = 0.50, a = 12.8480(2) Å, R wp = 7.64%, R F = 3.10%. They are isostructural to cubic KBSi 2 O 6 with the space group I 4…
Abstract The adsorption of imidazole on a roughened polycrystalline iron electrode was investigated by the SERS technique at pH values of neutral, 11 and 14 and compared with those from each solution. The results indicated that imidazole was adsorbed as mainly the neutral form and/or a certain amount of ylide form on…
Based on experimentally motivated assumptions, a new kinetic model of protein crystallization by mass-convection than by bulk diffusion is proposed. It is assumed that the charged-mass conservation law is being fulfilled, and that the attractive potential is of (screened) electrostatic nature. The role of the double-l…
Abstract Sedimentary zeolite occurrences are widespread in Central and Western Anatolia, Turkey. Erionite occurrences in Central Anatolia have significant health implications for inhabitants of the region. The widespread occurrences of zeolites are generally associated with volcano-sedimentary rocks and consist of low…
Control over crystallographic orientation in ceramic thin films is important for highly anisotropic structures. Layered perovskites, like Bi 4 Ti 3 O 12 , have interesting properties associated with their ferroelectric nature, which may be fully exploited only when films are highly textured. Textured films of this tit…
I determined the phase boundaries for regularly branched block copolymers in the self-consistent classical path, circular/spherical unit cell approximation. In contrast to the case for linear chains, end-free “dead” zones are highly suppressed for highly branched molecules, greatly simplifying the integral equations t…
In an attempt to relate architecture to physical properties through a systematic study of degree of branching (DB), we recently reported the copolymerization of a series of AB/AB 2 monomers ranging from 0 to 1 mole fraction AB monomer content ( x AB ). However, the DB of copolymers with 0.25 < x AB < 1.0 were not meas…
A new organic ligand bearing four coordination sites that may be metallated in a stepwise manner is described, together with its CuII and FeII derivatives. This may be considered as the first ligand precursor for trimetallic systems.
Novel 2H-chromenes derived from hydroxycoumarins were synthesized, and their photochromic behaviour was studied under flash-photolysis conditions, showing a wide absorption range in the visible region. All the compounds exhibit low fluorescence, which apparently has no negative effect on their photochromic properties.
In the framework of perturbation theory, the first several one-particle energies and wave functions for electrons and holes (six for each) in spherical silicon quantum dots are obtained in the envelope function approximation ( kp method). It is shown that the model of an isotropic dispersion relation with the mean rec…
The Mössbauer spectra of Ho2Fe17 and Ho2Fe17D3.8 have been measured between 4.2 and 295 K and analyzed with a model which takes into account both the disordered nonstoichiometric hexagonal Th2Ni17-like structure and the basal orientation of the iron magnetic moments. The isomer shifts of the five crystallographically…
The high‐cycle high‐frequency fatigue behavior of a Nicalon‐fiber‐reinforced calcium aluminosilicate ceramic composite was investigated. A key goal of the room‐temperature fatigue experiments was to determine if a true fatigue limit or endurance limit existed for this ceramic matrix composite. Although no fatigue fail…
The optical absorption spectra of LaMnO 3 single crystals, pure and slightly doped with Ce and Sr (7%), were studied in the middle IR region. Ellipsometry measurements were performed in the visible region to determine real and imaginary permittivity parts. The energies of the onset of indirect transitions in LaMnO 3 a…
A new Monte Carlo move for polymer simulations is presented. The “wormhole” move is build out of reptation steps and allows a polymer to reptate through a hole in space; it is able to completely displace a polymer in time N2 (with N the polymer length) even at high density. This move can be used in a similar way as co…
Dimethylimidazolidinone/lithium chloride (DMI/LiCL) is shown to be an effective solvent system for a variety of celluloses, including the high molecular weight cellulose of cotton, when a swelling pretreatment in sodium hydroxide is incorporated. DMI/0.5% LiCl is suitable for use as a mobile phase in gel permeation ch…
FUNCTIONALIZED SILICA OBTAIN BY SOL-GEL METHOD. Some aspects of the chemistry involved in the preparation and characterization of functionalized silicon oxide by sol-gel method are considered in this work. The synthesis was performed with different silicon alcoxide precursors and the influence of the acid and basic ca…