Materials Literature
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In vitro degradation studies of devices fabricated from polylactic acid (PLA) and polyglycolic acid (PGA) are usually performed at the physiologic 37°C and often take long periods of time to complete. The objective of the present study was to examine the degradation of a 50:50 PLA-PGA copolymer over a wide temperature…
Using a mixture of cetyltrimethylammonium bromide and carboxylate anionic surfactant (CnH2n+1COONa, n = 11, 13, 15, 17) as templates, siliceous MCM-48 is synthesized with low molar ratio (0.168:1) of mixed surfactants to silica and low concentration (5 wt %) of mixed surfactants.
In 2 O 3 exhibits a dramatic increase in solubility of SnO 2 and ZnO when they are cosubstituted into In 2 O 3 . The resultant material, In 2-2 x Sn x Zn x O 3-δ with x = 0−0.4, displays the same order of magnitude conductivity and transparency compared with bulk ITO (tin-doped indium oxide). Rapid quenching of In 2-2…
The two compounds CoCu(obbz)(H 2 O) 4 ·2H 2 O ( I ) and CoCu(obze)(H 2 O) 4 ·2H 2 O ( II ) have been synthesized, and their crystal structures have been determined at room temperature. Both compounds crystallize in the monoclinic system, space group P 2 1 / n . The lattice parameters are a = 7.8190(6) Å, b = 12.534(2)…
Among the many developments associated with sol−gel processing of particular relevance for information processing and optics applications is the preparation of photochromic sol−gel materials. If these materials are properly processed as thin films or attached to optical fibers, throughout the design of an adequate the…
The kinetics of the CO + NO and CO + O 2 reactions have been studied over several different Pd/Al 2 O 3 powder catalysts covering a wide range of average Pd particle sizes. The structure-insensitive nature of the CO + O 2 reaction over Pd has been exploited to determine the relative dispersions in several Pd/Al 2 O 3…
[ N, N ‘-Ethylenebis( o -( tert -butyl- p -methylsalicylaldiminato)]oxovanadium(IV) ( 1 ), [ N, N ‘-propanediylbis( o -( tert -butyl- p -methylsalicylaldiminato)]oxovanadium(IV) ( 2 ), bis( N -methylsalicylaldiminato)oxovanadium(IV) ( 3 ), bis( N -isopropyl- o -methylsalicylaldiminato)oxovanadium(IV) ( 4 ), and, bis(…
Low-energy phonons were studied in the ferromagnetic and paramagnetic phases of the Heusler alloy ${\mathrm{Ni}}_{2}\mathrm{MnGa}.$ The investigated sample shows a martensitic phase transformation with a transition temperature ${T}_{M}\ensuremath{\approx}284\mathrm{K},$ only about 80 K below the Curie temperature. The…
The emergence of the synchrotron radiation center in the past decade has resulted in a tremendous development of various techniques. XAS is an efficient tool for describing local organization in materials such as nanometer-scale metallic clusters but is insensitive to polydispersity. Ab initio calculations of the diff…
A mathematical model of a complete cell containing a porous intercalation electrode with two characteristic particle sizes is presented. Galvanostatic cycling and relaxation phenomena on open‐circuit are compared to a cell with a single particle size. Electrodes with a particle‐size distribution show modestly inferior…
Abstract The acidic properties of acid-modified montmorillonite and vermiculite were determined by pyridine and ammonia adsorption to correlate with the alkylating and dehydrating activity of the activated samples. Treatment of the minerals with different concentrations of hydrochloric acid results in the variation of…
Abstract The effects of exchanged cation and layer charge on the sorption of water and ethylene glycol monoethyl ether (EGME) vapors on montmorillonite have been studied on SAz-1 and SWy-1 source clays, each exchanged respectively with Ca, Na, K, Cs and tetramethylammonium (TMA) cations. The corresponding lattice expa…
[Cu(hyetrz) 3 ](ClO 4 ) 2 ·3H 2 O (hyetrz = 4-(2-hydroxyethyl)-1,2,4-triazole) represents the first structurally characterized metal(II) chain compound containing triple N 1, N 2 -1,2,4-triazole bridges. The structure has been solved at 298 K by single-crystal X-ray analysis. catena -Poly[μ-tris(4-(2-hydroxyethyl)-1,2…
We have performed magnetic measurements on a diluted system of $\ensuremath{\gamma}\ensuremath{-}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$ nanoparticles $(d\ensuremath{\sim}7 \mathrm{nm})$, and on a ferritin sample. In both cases, the zero-field cooled (ZFC) peak presents a nonmonotonic field dependence, as has already been…
High molecular mass and high regioregularity favor the more common polymorph (form I) of poly(3-alkylthiophenes) and substantially extend toward high temperatures the existence domain of the 2D mesomorphic phase, which these systems access above 70−80 °C. Morphological observations indicate that in thin films of form…
The effect of relatively small additions (1‐5 wt%) of nickel, nickel boride (NiB), and iron to promote the liquid‐phase sintering of titanium diboride (TiB 2 ) has been studied. Carbon also was added to some samples, to reduce the amount of oxygen impurities in the TiB 2 ceramics. Green bodies that were formed by unia…
Abstract A combined powder X-ray diffraction (XRD) and X-ray absorption (XAS) study of Fe(III) cation ordering within pyroaurite is described. It is concluded that there is no correlation between Fe(III) cation positions over distances of a few tens of angstroms, but that there is a very high level of local ordering,…
Water-soluble sodium poly(2-(3-thienyloxy)ethanesulfonate) and sodium poly(2-(4-methyl-3-thienyloxy)ethanesulfonate) have been synthesized. The sulfonic acid form of these new polymers has revealed a self-acid-doping reaction that leads to stable, highly conducting (0.5−5 S/cm) materials together with low absorption i…
We apply the molecular kinetic theory of wetting to the relaxation of the dynamic contact angle during the spreading of liquid droplets on solid surfaces. Experimental data have been obtained for several solid−liquid combinations and are successfully fitted using the theory. Physical parameters are extracted and inter…
The primary structure of the alpha-chain of preCol-D (molecular mass = 80 kDa), a tanned collagenous protein predominating in the distal portion of the byssal threads of the mussel Mytilus edulis, was deduced from cDNA to encode an unprecedented natural block copolymer with three major domain types: a central collagen…