Materials Literature
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The effect of tolyltriazole (TTA) on the corrosion of Al‐Cu, Al‐Si‐Cu and Al‐Cu‐Fe alloys in HCl (pH = 0.5) and NaCl (pH = 6 and 11) respectively at 15 ○ C, 25 ○ C and 35 ○ C has been studied by electrochemical methods. Corrosion potentials, corrosion rates, polarization resistances, inhibition efficiencies and activa…
The line tension of a dislocation is measured in a vertical smectic-A film as a function of temperature and film thickness. There are two contributions to the line tension: a bulk contribution that corresponds to the energy of the dislocation in an infinite medium and a surface correction that accounts for interaction…
A finite-element full-vectorial beam-propagation method is presented, for the first time, for the analysis of 3-D anisotropic optical waveguides. Full 3/spl times/3 permittivity and permeability tensors are considered. The formulation takes into account the polarization dependence and the component coupling due to the…
A simple method for the fabrication of nanocrystalline Cu 4 O 3 in polyaniline is reported. An aqueous solution of copper(II) acetate and aniline (1:10 mole ratio) is irradiated by ultrasound to produce nanophased Cu 4 O 3 embedded in a polyaniline matrix. The as-prepared Cu 4 O 3 - polyaniline is characterized by X-r…
An inspection technique based on angular dispersive X-ray diffraction (ADXRD) has been developed to chemically specific detection of explosives for screening applications. The technique identifies explosives from benign materials using the characteristic Bragg features seen in coherently scattered X-rays. To implement…
Poly(3-hydroxyalkanoate)s, PHAs, containing pendant carboxyl groups were prepared by the chemical modification of unsaturated PHAs using potassium permanganate (KMnO4) at 55°C, although there is a severe loss in molecular weight of PHAs during the reaction. The introduction of carboxylic groups in the products was ver…
Several previous studies of ${\mathrm{K}}_{1\ensuremath{-}x}{\mathrm{Li}}_{x}{\mathrm{TaO}}_{3}$ (KLT) have revealed the presence, above the structural transition, of polar nanoregions. Recently, these have been shown to play an essential role in the relaxor behavior of KLT. In order to characterize these regions, we…
Photoinduced electron transfer processes between C 60 / C 70 and phthalocyanines such as tetra-tert-butylphthalocyanine ( H 2 TBPc ) and its zinc derivative ( ZnTBPc ) in polar solvents have been studied by observing the transient absorption spectra in the visible and near-IR regions. Upon predominant excitation of TB…
The electrical transport in quasiperiodic systems at zero temperature is studied by means of the Kubo-Greenwood formula within a tight-binding model. Their dc conductivity is compared with that obtained from the Landauer formula. Special attention is paid to the transparent states, whose transmittance is unity. The ac…
Monoclinic and hexagonal forms of celsians (BaAl 2 Si 2 O 8 ) were synthesized by hydrolysis–polycondensation of Si/Al alkoxide mixtures. Dilatometry, Raman scattering, IR absorption, and X‐ray diffraction techniques were used to identify various hexacelsian phases and their conversion into the monoclinic phase as a f…
Phase‐pure perovskite Pb(Zn x Mg 1– x ) 1/3 Nb 2/3 O 3 solid solution (PZ x M 1– x N) is obtained for x ≦ 0.7 by heating a milled stoichiometric mixture of PbO, Mg(OH) 2 , Nb 2 O 5 , and 2ZnCO 3 ·3Zn(OH) 2 ·H 2 O at 1100°C for 1 h. Percent perovskite ( f P ) with respect to total crystalline phase decreases with incre…
Among other soft chemistry processes, sol-gel chemistry offers a versatile access to chemically designed new hybrid organic-inorganic materials. Two approaches to synthesize hybrids are presented: the hydrolysis of organo functional metal alkoxides or the assembly of nanobuilding blocks.
A generalized theory that includes short-range elasticity, long-range elasticity, and flow effects is used to simulate and characterize the shear flow of liquid crystalline materials as a function of the Deborah (De) and Ericksen (Er) numbers in the presence of fixed planar director boundary conditions; the results ar…
Complex particles have been formed by the electrostatic association of protonated polystyrene- b -poly(2-vinylpyridine) (PS- b -PVPH + ) micelles with sodium poly(styrenesulfonate) (PSS - Na + ), all at pH 1. Light scattering demonstrates that there is a large mass excess of PSS - associated with each PS- b -PVPH + mi…
Abstract Owing to their large and chemically active surface, hydroxy-intercalated and pillared clays can be potent sorbents for organic compounds. The sorption behavior of Al and Zr-hydroxy-intercalated bentonite (HAl-, HZr-MX80), Al and Zr-pillared bentonite (Al-MX80, Zr-MX80), and a commercial Al-pillared bentonite…
The compound $({\mathrm{CH}}_{3}{)}_{2}{\mathrm{CHNH}}_{3}{\mathrm{CuCl}}_{3},$ which consists of ferromagnetic-dominant ferromagnetic and antiferromagnetic alternating Heisenberg chains with $S=1/2,$ is regarded as a Haldane system with $S=1$ at low temperatures because a pair of ferromagnetically coupled spins behav…
It is shown that the fraction f(u) of imaginary-frequency instantaneous normal modes (INM) may be defined and calculated in a random energy model (REM) of liquids. The configurational entropy S(c) and the averaged hopping rate among the states, R, are also obtained and related to f(u) with the results R approximately…
Abstract Two analogous inorganic-organic hybrids with a phyllosilicate-like structure SILMg1 and SILMg2, containing 3-aminopropyl- and N-propylethylenediaminetrimethoxysilane were synthesized through a sol-gel process. These hybrids adsorbed divalent cations of cobalt, nickel, copper, and zinc from aqueous solution to…
The dispersing behavior of MgO‐doped mullite suspension suitable for the production of reticulate ceramics by sponge impregnation was studied. Three deflocculants were tested and the optimum dispersing conditions for the mullite suspension were found. Electrokinetic studies of magnesia in water evidence that it underg…
We have described a method that maximizes the phase separation of graphitic particles (GP) and multiwalled carbon nanotubes (MWNT) in solutions of various organic polymeric hosts. This involves the formation of sediment and a solute. These components were characterized for MWNT and GP content using electron paramagnet…