Materials Literature
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In this paper we present results obtained on the preparation of amorphous silicas from aqueous solutions of the octahedral silicon complex K2[Si(C6H4O2)3]· 2H2O at approximately neutral pH conditions (initial pHs of 6.67 and 7.1) in the presence and absence of cellulose. 1H solution NMR was used to monitor complex con…
Polymers from 1,4:3,6-Dianhydrosorbitol 1,4:3,6-Dianhydrosorbitol and several similar dioles are easily accessible by technical processes. They can be used for the the synthesis of high molecular polyesters, polyurethanes and polycarbonates. The thermal and mechanical properties of the obtained polymers are similar to…
Abstract SERS spectra of cytosine, 1‐methylcytosine, 5‐methylcytosine and 1,5‐dimethylcytosine on silver and on copper colloids are reported. A study of the influence of pH on the normal Raman spectra of these compounds was made in order to understand better the behaviour of these molecules on metal surfaces. The resu…
A hysteresis controller with a sinusoidal band for current regulation is described. The behavior of the conventional fixed-band controller and the proposed sinusoidal band controller has been thoroughly studied. Simulation results demonstrate that with no lockout (permitting a very high switching frequency) the curren…
New viologens, in which two pyridinium moieties are linked by a central five-membered heteroaromatic or phenylene framework, giving stable radical cations on single electron reduction and showing an intense fluorescence emission are efficiently synthesized and characterized.
The mechanical behavior and the effect of deformation on the martensitic transformation of Ti44Ni47Nb9 alloy were investigated in detail by tensile tests and electrical resistance measurements. The tensile behavior at various temperatures, the effect of annealing temperature after cold work and the aging effect were s…
A free boundary value problem is considered modeling solidification of a liquid by making use of the phase field approach as it was introduced by G. Caginalp [1] and others. Existence and uniqueness is proved as well as stability under mild assumptions. But the main goal of this paper is to establish results for the d…
Five species of salps retained plastic beads ≥2.5 μm diameter with high (≥60%) efficiency, while 1.0 μm beads were retained with low (≤15%) efficiency in all but one experiment.
Wettability and ESCA studies have been carried out using unextracted and extracted kraft pulps with different amounts of lignin. The effect of oxygen plasma treatment was investigated. The wettability was studied by placing a drop of water on a sheet made from the pulp and following the decrease in drop volume and app…
A novel liquid-crystalline material, S-2-chloropropyl 4′-(4″-n-nonyloxyphenylpropioloyloxy)biphenyl-4-carboxylate (902C13T), which undergoes an inversion of helical-twist sense in the cholesteric phase, was prepared and its physical properties were investigated. The behaviour of the pitch and the twist sense of the he…
It is possible to incorporate up to eight Ti ions per unit cell, which is probably the maximum, into the MFI structure (TS-1) using our improved synthesis procedure; 29Si NMR studies have helped in evolving the sysnthesis route.
The equilibrium structure of a monolayer formed by long polyelectrolyte chains grafted at one end onto an impermeable planar surface is analyzed. In contrast to the case of uncharged grafted polymer layer the unit density profile in a swollen state is not of the parabolic, but o the exponential type. The decrease in t…
Direct correlations are made between the extent of chromium depletion at grain boundaries and intergranular stress corrosion cracking (IGSCC) of 304 stainless steel during slow-strain-rate (SSR) tensile tests in 288 °C air-saturated water. IGSCC was found to depend on the minimum chromium concentration, the spacing of…
Current models of nutrient utilization by planktonic algae generally assume that cells transport nutrients continuously. This assumption is violated in the case of Si utilization by diatoms. Silicic acid transport is confined to specific portions of the cell cycle such that only a fraction of the cells in a population…
Description Describes current research on the effects of radiation on structural materials. The section on Ceramics and Nuclear Fuels has five papers that reflect this interest. Other topics include: • Irradiation facilities • Current commercial power reactor systems • Micro structural characterization of irradiation…
Spirobenzopyran derivatives carrying a monoazacrown moiety, such as 12-crown-4, 15-crown-5, and 18-crown-6 moieties, and their acyclic analogue, at the 8-position have been synthesized. Alkali metal ion complexation by the crowned spirobenzopyrans, followed by isomerization to the corresponding merocyanine form, and t…
Physiological stress was quantified in specimens of the European flat oyster Ostrea edulis, acclimated to a matrix of temperature (5–25°C) and salinity (16–34%o) conditions, using the Scope for Growth (SFG) index. Variations in the index were interpreted from the responses of its components, absorption efficiency, fil…
The structural and electronic properties of cubic and tetragonal zirconia (${\mathrm{ZrO}}_{2}$) are studied using a periodic ab initio Hartree-Fock method. Only valence electrons are treated explicitly, while effective core potentials are used for describing core electrons. The equilibrium geometries and elastic prop…
Al2O3/SiC nanocomposites exhibited the high fracture toughness and strength at room temperature and good high-temperature mechanical properties. These significant improvements of mechanical properties were contributed to the dispersion of nanometer-size SiC particle within Al2O3 matrix grains. In this paper, the sinte…
A versatile approach to dendritic macromolecules with aromatic polyester inner structure and a readily modified hydrophobic/hydrophilic ‘surface’ is described. The polyester fragments are prepared by a convergent growth process involving 3,5-bis(benzyloxy)benzoic acid as the ‘surface’ or chain-ending moiety and trichl…