Materials Literature
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Molecular dynamics simulations for γ-Al2O3 and La3+-doped γ-Al2O3 crystals have been performed. From bulk simulations a description of the crystal-terminating layers in both doped and pure alumina solids is reported. The molecular dynamics simulations allow us to describe systematically for the first time the surface…
Three alumina preparations, doped with ca. 3% CaO and corresponding to the γ-, δ,θ- and α-Al2O3 phases, respectively, have been studied by XRD, TEM and FTIR spectroscopy. Owing to the presence of Ca, no bulk phase stabilization/destabilization effects were observed, but the particle morphology of the γ- and α-phases w…
We review recent experimental studies of smectic A layering of asymmetric mesogens with emphasis on their relationship to phase transition physics. The formation of one and two dimensional lattices with long range order in the positions of the heads (tails) of molecules is considered as having either a polar or a ster…
Raman spectroscopy is nondestructive and relatively rapid and is well suited for the characterization of carbon films. The Raman spectra of a-C and a-C:H films consisting of two broad and overlapped features between 1000 and 1600 cm/sup -1/ have been obtained. Specific features in the Raman spectra are empirically cor…
Abstract Electrical conductivity and the Seebeck coefficient of compositions in the system Y 1- y Ca y MnO 3 and La 1- y Ca y MnO 3 were studied to determine the mechanism of electrical transport and defect structure. Electrical conduction appeared to occur via a small polaron hopping mechanism for compositions with 0…
Abstract Paramagnetic impurities, Fe 3+, Mn 2+and vanadyl (VO 2+) ions, along with paramagnetic radiation-induced defect centers, trapped holes, have been investigated with electron paramagnetic resonance (EPR) in more than 350 kaolin samples from different localities. The trace elements determined are either substitu…
The anodic polarisation behaviour of Ni–Ti shape memory alloy (SMA) in three different microstructural conditions, namely parent phase (β), martensite phase, and 30% cold worked martensite phase, was studied in simulated human body media, namely Hank's physiological solution and artificial saliva. Annealed 316L stainl…
Micelle-forming block copolymer–drug conjugates, Adriamycin-conjugated polyethylene glycol–poly(aspartic acid) block copolymers (PEG-P[Asp(ADR)]), were synthesized in eight compositions with varying chain lengths of the segments constituting the block co-polymer. The antitumor activity of this micelle-forming polymeri…
Abstract
Layered perovskite oxides of the formula ACa~,La,Nb3-,Ti,010 (A = K, Rb, Cs and 0 < x d 2) have been prepared. The members adopt the structures of the parent ACazNb3010. Interlayer alkali cations in the niobium-titanium oxide series can be ion-exchanged with Li+, Na+, NH4+, or H+ to give new derivatives. Intercalation…
Oxygen transport in many ionically conducting oxides occurs by diffusion or migration of oxygen-ion vacancies. An important issue in our understanding of these materials is the mechanism by which vacancies become trapped or ordered, and how this process affects transport. In this paper we reinvestigate the mechanism o…
The photocatalytic oxidation of liquid propan-2-ol to propanone has been investigated using semiconductor–zeolite composites consisting of either CdS or TiO2 in Y zeolite. CdS-based composites were prepared by cation exchange with Cd2+ followed by sulfidation with either Na2S or H2S, whereas TiO2-based composite was p…
The heat capacity Cp of UO2 was measured in a laboratory experiment where sintered 0.5-to 1-mm-diam microspheres were heated by four tetrahedrally oriented laser beams in an inert-gas-filled autoclave at pressures up to ∼1000 bar. The sample, suspended by a tungsten needle, was heated to 8000 K during pulses of a few…
Abstract With a FT Raman spectrometer highly resolved and reliable Raman spectra of B 4.3 C were obtained largely refuting previous results of other authors. The symmetry selection rules of IR and Raman active phonons are proved to hold. The most prominent Raman doublet at 270/320 and that at 869/928 cm −1 are due to…
The diffusion problem with internal and external resistances to misture transport is theoretically analysed with special attention paid to wood drying problems. The coefficients involved are all as ...
Fourier transform infrared absorption (FTIR) spectroscopy has been used to study a discotic liquid crystal. IR spectra are reported as a function of temperature for hexapentyloxytriphenylene (H5T). The order parameter S has been determined using unpolarized radiation and by comparing the spectra of the discotic phase…
The aerospace and naval industries both have a need for lightweight materials that can operate under extreme conditions, and yet retain their basic mechanical properties for long duration. Many of the papers presented in STP 1174 address on-going research
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhotochemistry of axially chiral (arylmethylene)cycloalkanes: a search for suitable photoswitchable liquid crystalline materialsRobert P. Lemieux and Gary B. SchusterCite this: J. Org. Chem. 1993, 58, 1, 100–110Publication Date (Print):January 1, 1993Publication History Publ…
A two-dimensional computer analysis of the surface charging on angled insulators has been performed by using the Monte Carlo simulation method. Results are compared to the charge in equilibrium model, originally proposed by C.H. de Tourreil and K.D. Srivastava (1973).>
Abstract The synthesis of the octasubstituted phthalocyanine 1 , highly soluble in organic solvents, is described. Its aggregation properties in different solvents and in the presence of alkaline, alkaline earth, and ammonium salts are studied.