Materials Literature
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A method is described which uses a scanning electron microscope for the investigation of charge trapping in insulators under electron bombardment. The technique commonly used to deduce the amount of trapped charge and its spatial extent is based on the mirror effect, while in the present approach the electron-beam def…
Amorphous carbon nitride films containing increasing concentrations of nitrogen were deposited by ion beam assisted deposition at a substrate temperature of 150 °C. The relationship between the deposition conditions and the chemical bonding structure was investigated by x-ray photoelectron, ultraviolet photoelectron,…
A quasi-harmonic molecular-mean-field model for analyzing anharmonic temperature evolution of anisotropic displacement parameters is described. Anharmonic effects are taken into account through a Gruneisen-type temperature dependence of effective vibrational frequencies. The method is applied to neutron and X-ray diff…
Large amounts of hydrogen are produced as a result of the anoxic corrosion of iron in the proposed container materials for some geologic repositories. Another hydrogen source, less important than the anoxic corrosion of iron, is the radiolysis of water by the spent fuel radiation. Gas phase formation occurs when the p…
The influence of surface states, defects and adsorbates on the electronic properties of diamond surfaces are discussed. As far as surface states and reconstructions are concerned the principal crystallographic surfaces, (100), (111) and (110), are essentially understood in their adsorbate free form and also when termi…
Two series of homopolyimides based on oxydiphthalic anhydride and bisphenol A bisether-4-diphthalic anhydride were synthesized with 12 kinds of aromatic diamines. Several thermo-processable homopolyimides were the focus of further investigation. The structure–property relationships of these homopolyimides were examine…
Silicon dioxide thin films are deposited on (100) silicon substrates at low pressure (5 mTorr), from O2/tetraethoxysilane (TEOS) helicon plasmas. The reactor is operated at 300 W radio frequency power without any intentional heating or biasing of the substrate. The samples are characterized using infrared spectroscopy…
The smectic-A phase boundaries of a hard-spherocylinder fluid are calculated using a density-functional theory based on one proposed earlier by Somoza and Tarazona [Phys. Rev. A 41, 965 (1990)]. Our calculations do not employ the translation-rotation decoupling approximation used in previous density-functional theorie…
A one-bath process to apply both antimicrobial and fluorochemical repellent finishes to nonwoven surgical gown fabrics is investigated in this study. The finishes are applied to two nonwovens: a polypropylene spunbonded/meltblown/spunbonded fabric and a wood pulp/polyester spunlaced fabric. Four different add-on level…
Detailed analysis of the microstructure of grain boundaries, especially triple‐grain and multiple‐grain junctions, in ZnO varistor materials has been performed using transmission electron microscopy. Different polymorphs of Bi 2 O 3 are shown to exhibit different wetting properties on ZnO interfaces. Recent investigat…
Magnetic and structural transitions at low temperatures are exhibited by the novel open-framework cobalt(II) phosphate of the composition [enH2][Co3.5(PO4)3] (en=ethylenediamine), the structure of which contains 12-membered channels (see picture). In the presence of a magnetic field, the compound undergoes a transitio…
Pseudomonas oleovorans is capable of producing poly(3-hydroxyalkanoates) (PHAs) as intracellular storage material. To analyze the possible involvement of phaD in medium-chain-length (MCL) PHA biosynthesis, we generated a phaD knockout mutant by homologous recombination. Upon disruption of the phaD gene, MCL PHA polyme…
Highly photoconductive devices with very broad absorbance spectra are presented here. These double-layer devices consist of nanocrystals of titanyl phthalocyanine (see Figure, M=TiO) dispersed in thin films of a conjugated ladder polymer (BBL). The presence of the BBL increases the spectral range for commercial TiOPc…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTExploring the Limits of Efficiency of Proton-Transfer Catalysis in Models and EnzymesEwa Hartwell, David R. W. Hodgson, and Anthony J. KirbyView Author Information University Chemical Laboratory, Cambridge University Cambridge CB2 1EW, UK Cite this: J. Am. Chem. Soc. 2…
In the Sr–Bi–Ta–Nb–O system, three crystallographic phases are known to exist: the SrBi 2 (Ta 1- x Nb x )O 9 (SBTN) perovskite, fluorite and pyrochlore phases. It is considered that the fluorite phase is a low-temperature phase of SBT, which tends to grow in excess bismuth compositions, and the pyrochlore phase tends…
Both phenomenological and molecular-statistical theories of the anticlinic smectic-C(A) phase (Sm-C(A)) are considered in detail. The anticlinic structure produces antiferroelectricity in the chiral smectic-C(A) phase (Sm-C(A)*). The molecular theory is based on a simple model potential which stabilizes Sm-C(A) with r…
Two electrochemical methods designed for the synthesis of polypyrrole (PPy) wires and nanotubules are the topic of this paper. The concept that allows the morphology of PPy to be controlled is discussed for each method, and the performances of the two complementary techniques are compared in terms of dimension, shape…
The structure of the Sr 0.75 Ba 0.25 Nb 2 O 6 single crystal has been investigated by x-ray diffraction. The occupancies of the Ba and Sr sites in two structural channels are determined. It is found that these sites are split in the large (pentagonal) channel. A qualitative correlation is revealed between the smearing…
Banana-shaped molecules having two side wings attached to a bent core may exhibit liquid crystallinity. The most studied material is 8-OPIMB that comprises 1,3-dihydroxybenzene as a central core, a Schiff 's base moieties as the wing groups and octyloxy tail groups. To clarify the effect of chemical structure on the l…
The first-principles calculations for FeMn and MnPt alloys both of ordered and disordered phases have been performed with the TB-LMTO method combined with the CPA. The magnetic structure of FeMn in the disordered phase is suggested to be non-collinear 3Q structure where the average moment is around 1.7 µ B and the Nee…