Materials Literature
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In a previous paper it was shown that in-crystal ion polarizabilities derived from low-frequency precision measurements of the dielectric constants of single-crystal oxides can be given a quantitative interpretation using a quantum mechanically based result for a single, completely filled, electron subshell. In this p…
The compressibility of wurtzitic boron nitride (wBN) taken in mixture with cubic BN has been measured at room temperature up to 66 GPa, using a diamond anvil cell and powder diffraction of synchrotron radiation. From the obtained pressure-volume relation for wBN the isothermal bulk modulus of B0=375±9 GPa and its firs…
We report the results of magnetization measurements on pseudomorphic (fully strained) c-axis oriented colossal magnetoresistance manganite thin films grown by molecular beam epitaxy. We observe uniaxial magnetic anisotropy (hard axis/easy plane) with the easy plane being the film plane. Within the plane a weaker biaxi…
A method for the calculation of the temperature dependence of dielectric and piezoelectric responses, based on the use of a first-principles effective Hamiltonian, is described. Results are presented for the ferroelectric perovskite PbTiO3. While the method includes only the soft-mode contributions to the responses, i…
A method of controlling threading dislocation densities in Ge on Si involving graded SiGe layers and chemical-mechanical polishing (CMP) is presented. This method has allowed us to grow a relaxed graded buffer to 100% Ge without the increase in threading dislocation density normally observed in thick graded structures…
We described genetically engineered syntheses of tandem repetitive polypeptides consisting of glycine-rich sequence, GlyLeuGlyGlyGlnGlyGlyGlyAlaGlyGlnGlyGlyTyrGly, designated SCAP(1), in spidroin 1 of spider dragline silk from Nephila clavipes and the secondary conformational analyses in the solid state by Fourier tra…
A variety of approximate methods for efficient modeling of large lanthanide (Ln) complexes were studied. Attention was paid to ligand motifs prevalent in Ln coordination chemistry. Gadolinium was chosen given its central location in the Ln series and its importance in areas such as magnetic resonance imaging. A semiem…
Continuing with the evaluation of costabilizers along with preheated metal stearates to stabilize poly(vinyl chloride) (PVC), pentaerythritol was chosen as a long-term costabilizer. During normal stabilization conditions, the polyol enhances the induction time to degradation but produces large amounts of polyenes. The…
Traditional and gradient interpenetrating polymer networks (IPNs) of various composition have been prepared on the basis of crosslinked siliceous polyurethane and a copolymer of butylmethacrylate and dimethacrylate triethylene glycol. For various layers of gradient IPNs cut from the surface to the center of the sample…
The mixed alcohols were synthesized at different reaction temperatures, different GHSVs, and different pressures over K−MoO 3 supported on different supports such as γ-Al 2 O 3 and SiO 2 . The ammonia adsorption over the catalysts was studied using temperature program desorption (TPD). The ethanol decomposition was st…
Continuing with the evaluation of costabilizers along with preheated metal stearates to stabilize poly(vinyl chloride) (PVC), pentaerythritol was chosen as a long-term costabilizer. During normal stabilization conditions, the polyol enhances the induction time to degradation but produces large amounts of polyenes. The…
Dichlorocarbene-modified styrene–butadiene rubber (SBR) prepared by the alkaline hydrolysis of chloroform using cetyltrimethylammonium bromide as a phase-transfer agent resulted in a product that showed good mechanical properties, excellent flame resistance, solvent resistance, and good thermal stability. The activati…
The influence of a β-diketone on the already observed anomalous behavior of preheated metal stearates as stabilizers for PVC has been evaluated. During normal stabilization procedure, the addition of diketones reduce the stabilization times, but the pretreatment of the mixture of metal soaps or of the individual zinc…
Three series of poly(aryl ether sulfone)s (PAESs) containing the phthalazinone moiety in the polymer backbone were synthesized by solution polycondensation of bis(4-chlorophenyl) sulfone with three commercial bisphenols and 4-(4-hydroxyphenyl)-2,3-phthalazin-1-one. Bisphenol-A, hydroquinone, and bis(4-hydroxyphenyl) s…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Molecular Wire Approach to Sensory Signal AmplificationTimothy M. SwagerView Author Information Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 Cite this: Acc. Chem. Res. 1998, 31, 5, 201–207Publication Date (Web):April 4, 1…
Von Purpurfarben nach Grün wechselt die Farbe bei Zugabe von Tetrathiafulvalen (TTF) zum makrobicyclischen Rezeptor 14+, der sich aus einem Cyclobis(paraquat-p-phenylen)-Tetrakation und einem 1,5-Naphtho-p-phenylen-[36]krone-10-Makrocyclus mit gemeinsamem p-Phenylenring zusammensetzt. Das TTF-Molekül verdrängt dabei d…
Geomicrobiology: Interactions Between Microbes and Minerals. JILLIAN F. BANFIELD and KENNETH H. NEALSON, Eds. Mineralogical Society of America, Washington, DC, 1997. xvi, 448 pp., illus. Paper, $32. ISBN 0-939950-45-6. Reviews in Mineralogy, vol. 35.
Trotz größerer Entfernung sind die Porphyringruppen in 1 stärker konjugiert als in der analogen Verbindung, in der sie nur durch eine Butadiin-Einheit verbrückt sind, was sich in einer bathochromen Verschiebung von Absorptions- und Emissionsbanden zeigt.
A place in the sun for solutions of [(Ph3P)2N]2[Mn(CN)6] provides—by photochemical degradation—[MnII(CN)4]2− ions, the only homoleptic cyanide complex ion that is high spin (structure depicted on the right). Magnetic measurements indicate a high-spin 6A1 ground state (S=5/2), and the cyanide ligands are virtually enti…
A continuous process for the synthesis of mesoporous silicates such as MCM-41 at room temperature has been achieved by employing a tubular reactor in which tetraethoxysilane was used as the silicate source (see schematic representation below). The formation of the hexagonal mesophase, which was monitored by using in s…