Materials Literature
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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…
Die Änderungen des Oxidationszustands redoxaktiver Liganden ist eine leistungsfähige Methode, um die Reaktivität und auch die Selektivität gebundener Übergangsmetalle zu kontrollieren (siehe rechts). So konnte in einigen Fällen durch einfache Abspaltung eines Elektrons aus einem Metall-Ligand-Komplex die Reaktionsgesc…
We propose a new type of hybrid systems formed by conventional semiconductor nanostructures with the addition of remote insulating layers, where the electron-hole interaction is enhanced by combining quantum and dielectric confinement over different length scales. Due to the polarization charges induced by the dielect…
We report on a first-principles study of the structure of O/Rh(001) at half a monolayer of oxygen coverage, performed using density-functional theory. We find that oxygen atoms sit at the center of the black squares of a chess-board, $c(2\times 2)$, pattern. This structure is unstable against a rhomboid distortion of…
Crystal structures of wild-type tryptophan synthase alpha2beta2 complexes from Salmonella typhimurium were determined to investigate the mechanism of allosteric activation of the alpha-reaction by the aminoacrylate intermediate formed at the beta-active site. Using a flow cell, the aminoacrylate (A-A) intermediate of…
The microphase separation of a diblock copolymer melt confined by hard walls and in the presence of a gravitational field is simulated by means of a cell dynamical system model. It is found that the presence of hard walls normal to the gravitational field are key ingredients to the formation of well ordered lamellae i…
We use the maximally-localized Wannier function method to study bonding properties in amorphous silicon. This study represents, to our knowledge, the first application of the Wannier-function analysis to a disordered system. Our results show that, in the presence of disorder, this method is extremely helpful in provid…
The class of second-order curvilinear gratings consists of all the curvilinear gratings that are obtained by second-order spatial transformations of periodic gratings. It includes, for example, circular, elliptic, and hyperbolic gratings as well as circular, elliptic, and hyperbolic zone plates. Such structures occur…
Abstract The anticipated size of the world airliner market over the period 1997-2016, and the resultant requirements for aluminium plate and extrusions to satisfy potential Airbus wing box production is reviewed. The ‘value’ of technology and the threat posed by polymer composites to the future of aluminium alloys for…
Time-dependent chemical compositions for 13N and 15O induced in the air atmosphere of a high energy electron accelerator room have been studied using a computer simulation method. A radiation chemistry model was developed to describe the chemical reactions of 13N and 15O species with the air molecules and their radiol…
The complementary allocated pit address (CAPA) signal in a digital versatile rewritable disc (DVD-RAM) is susceptible to an objective lens radial shift; the reduction of its signal amplitude occurs and the S/N ratio decreases. To alleviate this situation, we propose a new readout signal processing scheme, the center s…
A core-shell microstructure is adopted to account for the unique resistivity-temperature (ρ– T ) behavior of (Pb 0.6 Sr 0.4 )TiO 3 materials prepared by the rapid thermal sintering (RTS) process. Instead of a V–shaped temperature coefficient of resistivity (VTCR) with critical temperature ( T ′ c1 ) at around 220°C, c…
Right- and left-handed polymer-dispersed cholesteric (chiral nematic) liquid-crystal (PDCLC) layers are stacked directly between a pair of substrates. Each layer in a device containing these stacked layers exhibits independent characteristics. This is because the PDCLC structure confines the liquid crystal (LC) within…
2nd update of database ICSD in 1998, CSD