Materials Literature
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Abstract The solubilization of the calcium soaps of long chain fatty acids by liquid fatty acids was observed. The solubilities of calcium palmitate, calcium laurate, and calcium oleate were 15.6, 22.8, and 53.3 wt%, respectively, in oleic acid at 40°C. The formation of an acid‐calcium soap complex was demonstrated by…
Abstract Upper Jurassic claystones of Kimmeridgian-Volgian(-Ryazanian) age are the main source rocks for oil in the Central Trough, North Sea. Drill cuttings and cores from the depth interval 2368–4548 m, the interval from early-mature to peak oil generation, have been investigated by high-resolution transmission elec…
The use of contrast agents in MRI is well established as a means to improve diagnosis. MRI diflers from other imaging modalities because signal and contrast are multiparametric in both the properties of the tissue and the method of measurement. Contrast depends on differences in proton-spin density, magnetic susceptib…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCalorimetric determination of the heats of protonation of the metal in (methyl-substituted cyclopentadienyl)iridium complexes, Cp'Ir(1,5-COD)John R. Sowa Jr. and Robert J. AngeliciCite this: J. Am. Chem. Soc. 1991, 113, 7, 2537–2544Publication Date (Print):March 1, 1991Publi…
Thin films of LiyV2O5 (0<y<1) were made by reactive dc magnetron sputtering of V followed by electrochemical treatment in LiClO4. X-ray diffractometry showed an orthorhombic structure that varied from nanocrystalline (n-X ) for unheated substrates to polycrystalline (p-X ) for substrates at 180 °C. Optic…
This paper focuses on the résponse of bubbles to sudden changes in the ambient pressure. Trains of bubbles with radii varying between 45 and 200 μm were exposed to various pressure steps, and their response was monitored by pulsed laser holography. The experiments were performed in a specially constructed chamber, all…
Abstract— Monomer and dimer absorption and emission spectra, and dimerization constants are reported for the diamide of the zinc‐tetracarboxyphthalocyanine in pure dimethylformamide (DMF) and in H 2 O/DMF mixtures at room temperature. The dimerization constant increases steadily with the water content. The monomer abs…
Vickers hardness measurements have been made at room temperature for four thermodynamically stable quasicrystals. The hardness value of Al-Li-Cu icosahedral quasicrystal is about 500 (kg/mm 2 ) and those of Al-transition metal quasicrystals are commonly around 1000, which is extremely high for aluminum based alloys. A…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPorphyrin sponges. Inversion disorder and inversion twinning in lattice clathrates based on five-coordinate metallotetraarylporphyrin complexesMarianne P. Byrn and Charles E. StrouseCite this: J. Am. Chem. Soc. 1991, 113, 7, 2501–2508Publication Date (Print):March 1, 1991Pub…
Klebsiella pneumoniae catabolizes both 4-hydroxyphenylacetic acid and 3-hydroxyphenylacetic acid via meta-cleavage of 3,4-dihydroxyphenylacetic acid, ultimately yielding pyruvate and succinate. The organism can synthesize two hydroxylases catalysing 3,4-dihydroxyphenylacetic acid formation, which differ in substrate s…
Abstract Cationic ring‐opening polymerization of e‐caprolactone using triethyloxonium hexafluorophosphate initiator in the presence of alcohol to produce low molecular weight polyester glycol was examined. The polymerization proceeded by an activated monomer mechanism; thus the polymer molecular weight increased direc…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTComplexation, luminescence, and energy transfer of cerium(3+) with a series of multidentate aminophosphonic acids in aqueous solutionSteven T. Frey and William D. Horrocks Jr.Cite this: Inorg. Chem. 1991, 30, 5, 1073–1079Publication Date (Print):March 1, 1991Publication Hist…
Abstract A review of relevant microscopic processes, both chemical and physical, which occur during suspension, bulk and emulsion polymerization (both before and after pressure drop) is given. The state of the art of kinetic modelling of monomer consumption rate, reactor pressure, molecular weight and short and long c…
We present a derivation of the microscopic expressions for the elastic constants of nematic liquid crystals within the density functional formalism. We recover the expressions of Poniewierski and Stecki for molecules with three planes of symmetry, but our general expression includes the effects of the relaxation in th…
Continuous stoichiometric silicon nitride fiber was produced by the pyrolysis of perhydropolysilazane. This high‐purity silicon nitride fiber is colorless and has high strength, modulus of elasticity, and thermal stability which are properties suitable for reinforcing plastics, metals, glasses, and even ceramics. The…
As-polymerized poly(L-lactide) test rods were sterilized by seven different specially designed computer-operated autoclaving programs. As a control, common hospital sterilization was performed. In all cases, the molecular weight decreased after sterilization. A short time high-temperature sterilization led to less mol…
At high temperatures in clean oxidizing environments, SiC forms a very protective SiO 2 film, but, in environments containing low levels of gaseous alkali salt contaminants or where condensed salts may deposit on the surface, the resistance of the film is significantly reduced. Oxidation kinetics of SiC were measured…
Albumin and fibrinogen were competitively adsorbed onto dimethyldichlorosilane-coated glass (DDS-glass) and platelet activation was examined as a function of the surface fibrinogen concentration. The weight ratio of albumin to fibrinogen in the adsorption solution was varied from 10 to 700. Platelet activation was qua…
We compared the relative toxicities of standard concentrations of two magnetic resonance imaging (MRI) contrast agents, ionic gadolinium diethylenetriaminepentacetic acid (DTPA) and low-osmolar gadolinium-1, 4, 7 tris (carboxymethyl)-10-(2'-hydroxypropyl)-1, 4, 7, 10 tetra-azacyclododecane (HP-DO3A) with that of the c…
The photoredox behavior of various iron meso-tetraarylporphyrins in ethanol-containing solvents is examined. The reduction of Fe(III) to Fe(II) is observed in every case under irradiation with light of 350-450 nm. The electron-drawing or -repelling power of the meso-aryl substituents are found to have a scarce influen…