Materials Literature
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The relationship between a composite and its constituents with respect to high‐temperature deformation behavior was investigated using the Al 2 O 3 ‐Y 3 Al 5 O 12 (YAG) eutectic system. The eutectic is essentially a composite with sapphire and YAG as the two phases with a volume fraction of YAG of 0.45. The deformatio…
Thermodiffusion, the cross coupling between temperature and concentration, is studied in dilute polymer solutions by forced Rayleigh light scattering. First a spatial temperature grating is created within the solution by absorption of an optical interference grating and subsequently a concentration grating builds up.…
In this perspective, some of the general phenomena associated with liquid-crystal behaviour are introduced before selective consideration is given to the effect which a metal can have when it forms part of a liquid-crystalline molecule.
A 3-D model of a protein can be constructed from its amino acid sequence and the 3-D structures of one or more homologues by annealing three sets of fragments: the structurally conserved regions, structurally variable regions and the side chains. The method encoded in the computer program COMPOSER was assessed by gene…
Abstract
Alkali-mediated reaction of 5,10,15,20-tetrakis(3′,5′-dihydroxyphenyl)porphine with dendritic bromide gives the novel porphyrin covalently encapsulated into a huge dendritic cage (‘caged’ porphyrin).
The geometry of gold–gold interactions in a group of 693 gold-containing crystal structures has been examined using data from the Cambridge Structural Database. These contacts occur in the range 2.50–4.00 Å. Intermolecular Au ⋯ Au contacts are formed by compounds of the type AuXY (X, Y = any element) with the X-Au–Au-…
Experimentally measured second-order nonlinear hyperpolarizability (βµ) data for a new series of donor-acceptor conjugated compounds containing tricyanovinyl acceptors and thiophene conjugating units, reveal that this combination results in a dramatic enhancement (αµ= 6000–9000 × 10–48 esu) of their molecular nonlinea…
Facile alkoxylation of 4′-chloro-2,2′ :6′,2″-terpyridine with the mono- and tri-hydroxylic cascade (dendritic) building blocks, 4-(3-hydroxypropyl)-4-(3-benzyloxypropyl)-1,7-bis(benzyloxy)heptane 4 and 4-amino-4-(3-hydroxypropyl)heptane-1,7-diol 3, has allowed the synthesis of a dodecaruthenium macromolecule 11 employ…
Conventional small-molecule methods of solving the phase problem from native data alone, without the use of heavy-atom derivatives, known fragment geometries or anomalous dispersion, have been tested on 0.9 A resolution data for two small proteins: rubredoxin, from Desulfovibrio vulgaris, and crambin. The presence of…
The four redox steps between the dication and the dianion of didodecylsexithiophene 1, a soluble oligothiophene with defined structure and chain length, were studied by a combination of in situ UV/VIS/near IR and ESR spectroscopy. The reversible dimerization 1˙+ → (1) provides a new description of the doping behavior…
The dosage redistribution and interfacial structure of a polysilicon film deposited by a novel two‐step continuous deposition of in situ doped and undoped polycrystalline silicon is described. A tungsten silicide film is deposited on the composite layers which then makes contacts with the p − substrate. The depth prof…
Nickel oxide supported on high-surface-area magnesia (123 m2 g–1) containing 10 wt.% nickel was prepared in a systematic way by the impregnation method. The problems associated with the reduction of nickel oxide due to formation of an NiO–MgO solid solution are discussed. At 673 K the interaction between NiO and MgO s…
A 4<i>f</i>-type optical system for performing matrix multiplication is presented. The system consists of a holographic mask and two Fourier lenses. With this system, the inner products of 4 x 8 and 8 x 4 matrices are calculated, yielding results that are in agreement with theoretical values.
A new rapid air-drying technique for scanning electron microscopy (SEM) with results comparable to critical point drying (CPD) has been developed. In earlier studies a trematode parasite and a fungus were used as test specimens. Here the application of the new method for SEM of some mammalian tissue is described. The…
XPS measurements of the core levels, including energy losses, and the valence band of a MgO(100) crystal are presented.
Ultraviolet optical properties near the edge of transparency (just above and below the band gap) of polycrystalline ALON (aluminum oxynitride, Al<sub>23</sub>O<sub>27</sub>N<sub>5</sub>) and spinel are not well characterized. The edge of transparency is commonly found to obey Urbach's rule, and this is the case for si…
A. V. Powell, Annu. Rep. Prog. Chem., Sect. C: Phys. Chem., 1993, 90, 177 DOI: 10.1039/PC9939000177
Hartman–Perdok theory enables classification of crystal faces as F, S or K faces. Only F faces should be present on growth forms as they grow slowly according to a layer mechanism. Such a classification can be quantified for ionic crystals by the calculation of attachment energies in electrostatic point-charge models.…
At present, several definitions of partial discharge inception voltage (PDIV) have been advanced. To establish the value of each of these definitions, four practical electrical insulating fluids are selected, and their PDIV is determined according to three of these different specifications. The results suggest that th…