Materials Literature
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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…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTCharacterization of Binary Solvent MixturesJ. Catalán, C. Díaz, and F. García-BlancoView Author Information Departamento de Química Física Aplicada, Universidad Autónoma de Madrid, Cantoblanco, E-28049 Madrid, Spain, and Departamento de Físico-Química, Facultad de Farmacia, Uni…
An alternative, pyroelectric effect based technique was developed for the direct measurement of the surface polarization in homogeneously and homeotropically oriented nematic cells as well as for the measurement of the flexoelectric polarization in hybrid aligned nematic cells. The pyroelectric response was measured w…
Closed analytical expressions for scattering intensity and other global structure factors are derived for a new solvable model of polydisperse sticky hard spheres. The starting point is the exact solution of the “mean spherical approximation” for hard core plus Yukawa potentials, in the limit of infinite amplitude and…
INTRODUCTION: Eye drops made from Euphrasia rostkoviana Hayne have been used in anthroposophical medicine for more than 70 years for the structuring of the fluid organism in the eye, especially in inflammatory and catarrhal conjunctivitis. The aim of this prospective cohort trial was to describe the efficacy and toler…