Materials Literature
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In this paper we report a time-resolved investigation of transients derived from curcumin, which may be intimately involved in the processes leading to its biological activity. Fluorescence and triplet quantum yields are respectively 0.06 and 0.11. The high percentage of internal conversion is proposed to proceed via…
Pressureless sintering of monolithic ceramics results in substantial shrinkage as the void space in the initially porous starting material is eliminated. Introduction of fibers or platelets inhibits sintering. Thus, when ceramic composites are made, processes other than sintering are used to achieve dense structures o…
Abstract Poly(propylene)s with narrow molecular weight distributions were prepared with various methylaluminoxane‐activated metallocene‐based Ziegler‐Natta catalysts to study the influence of randomly incorporated regio‐ and stereoirregularities on the crystallization behavior. As a function of the metallocene type an…
We describe here the experimental conditions under which the photoelectrochemical etching (PEC‐etching) of n‐type silicon in HF induces the formation of porous silicon. Two types of porous silicon are formed underneath an etch crater: a layer of nanoporous material with pores in the nanometer range on top of a macropo…
Pure Ta has been cold rolled and annealed at various temperatures. The crystallographic textures were studied by measuring X-ray pole figures and subsequently calculating the orientation distribution function. The microstructure was investigated via optical microscopy. The rolling textures were explained by dislocatio…
A photopyroelectric technique has been used to simultaneously measure the critical behavior of specific heat, thermal conductivity, and thermal diffusivity of ${\mathrm{Cr}}_{2}$${\mathrm{O}}_{3}$ at the antiferromagnetic-paramagnetic phase transition. An Ising-like behavior has been found for \ensuremath{\Vert}${\mat…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAtomic layer epitaxy growth of titanium dioxide thin films from titanium ethoxideMikko Ritala, Markku Leskela, and Eero RauhalaCite this: Chem. Mater. 1994, 6, 4, 556–561Publication Date (Print):April 1, 1994Publication History Published online1 May 2002Published inissue 1 A…
At the wall in a hybrid cell with strong anchoring, the nematic director is parallel to one wall and perpendicular to the other. Usually, the free energy is minimized by a configuration where the director orientation changes continuously with position across the cell. The boundary conditions can also be satisfied, how…
The kinetics of monoatomic steps in diffusion-controlled crystal growth and evaporation processes are investigated analytically using a Green's function approach. Integro-differential equations of motion for the steps are derived; a systematic linear stability analysis is carried out treating simultaneously perturbati…
Dielectric properties of lead magnesium niobate (PMN) and Ta-bearing strontium barium niobate (SBNT) were measured as a function of temperature, and the crystal structure of PMN was refined by the Rietveld analysis method. The results of structure refinement indicate that the volume of polar microregions (PMR) increas…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPolymerization of .epsilon.-Caprolactone by Divalent Samarium ComplexesWilliam J. Evans and Hideo KatsumataCite this: Macromolecules 1994, 27, 8, 2330–2332Publication Date (Print):April 1, 1994Publication History Published online1 May 2002Published inissue 1 April 1994https:…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMolecular Modeling of Polycarbonate. 1. Force Field, Static Structure, and Mechanical PropertiesCun Feng Fan, Tahir Cagin, Zhuo Min Chen, and Kennith A. SmithCite this: Macromolecules 1994, 27, 9, 2383–2391Publication Date (Print):April 1, 1994Publication History Published o…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAmorphous, biomimetic granules of polyhydroxybutyrate: preparation, characterization, and biological implicationsDaniel M. Horowitz and Jeremy K. M. SandersCite this: J. Am. Chem. Soc. 1994, 116, 7, 2695–2702Publication Date (Print):April 1, 1994Publication History Published…
Argon and carbon ion bombardment of p-diamond at 500–5000 eV in ultrahigh vacuum were studied by in situ x-ray photoelectron spectroscopy (XPS) and low energy electron diffraction analysis. Both argon and carbon ion bombardment at room temperature in the present energy range created a defective surface layer. The radi…
Abstract The binary exchange of cations on clays and soils is generally regarded as a thermodynamically reversible process. The literature on soil chemistry and geochemistry, however, abounds with reports on cation exchange reactions that appear to have only limited reversibility, i.e., that exhibit hysteresis. A sati…
A lumped-component equivalent circuit has been developed by our team to model the electric behavior of any two-winding transformer. This circuit is general: its topology is independent of shape, sizes, and technology chosen. Changing the sample results only in a change of numerical values. Moreover, this circuit is su…
Factors controlling the initiation and propagation of crevice corrosion on alloy 625 (UNS N06625) in ocean water of ambient temperature were explored within the contexts of the Oldfield-Sutton model for critical crevice corrosion solution (CCS) development and the ohmic criterion for crevice corrosion initiation. Data…
The cloned poly-3-hydroxybutyrate (PHB) synthesis pathway from Alcaligenes eutrophus has been introduced into sucrose-utilizing strains of Escherichia coli, Klebsiella aerogenes, and Klebsiella oxytoca. The plasmid-borne genes were well expressed in these environments and were able to mediate the production of signifi…
Ferroresonant overvoltages or undervoltages can occur in cable-fed power transformer installations when single phase switching or interrupting is practiced. This paper identifies the ferroresonant circuit as a nonlinear dynamical system. Analysis and classification methods are presented which provide new insight into…
Grain growth kinetics in alumina‐rich, zirconia–alumina composites have been examined as a function of volume fraction of zirconia. Both he microstructural scale and character alter during grain growth. Grain growth exponents between n = 3 and 4 were observed and have been rationalized in terms of current models for g…