Materials Literature
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Electron−hole pairs created upon optical excitation of conjugated dendrimers (fractal antenna macromolecules) are shown to be localized within segments connected by benzene rings substituted at the meta-position. The absorption spectra of two families of dendrimers are analyzed using collective electronic normal modes…
Raman spectra of the layered compound, antimony triiodide are reported for samples at ambient temperature and at pressures up to 16 GPa. Changes in the number of observed peaks and their wavenumbers, relative intensities and spectral linewidths are discussed. Evidence for reversible crystallographic phase transitions…
Article Redetermination of the crystal structure of copper(I) tetrathiovanadate (sulvanite), CU3VS4 was published on April 1, 1998 in the journal Zeitschrift für Kristallographie - New Crystal Structures (volume 213, issue 1-4).
This study describes the use of transmission electron holography to determine the mean inner potential of polystyrene. Spherical nanoparticles of amorphous polystyrene are studied so that the effect of specimen thickness on the phase shift of an incident electron wave can be separated from the intrinsic refractive pro…
Abstract Dissolved silver (Ag) in the presence of amorphous iron sulfide(FeS) rapidly equilibrates to ultra-trace levels ( ∼5 ng/L), which agrees with equilibrium calculations based on Ag2S solubility. This finding, along with the authors' discovery that crystalline Ag2S (acanthite) precipitates rapidly under supersat…
PbTiO3 nanocrystals were investigated by using Raman spectroscopy. The phonon modes in the nanocrystals exhibited an obvious frequency downshift as compared with bulk single crystals, and the mode frequencies in nanocrystalline PbTiO3 shifted up with annealing treatment. Size dependence of phonon modes in the nanocrys…
A lightning impulse causes substantial capacitive current in a water tree channel which, as a result of its small cross section, has relatively low conductance. Transient, nonlinear finite element computations with coupled thermal and electric fields for the geometry of a 15 kV XLPE dielectric cable indicate that an 8…
The ordering kinetics of cylindrical and spherical microdomains in a polystyrene-block-polyisoprene-block-polystyrene (SIS) copolymer were studied using synchrotron small-angle X-ray scattering (SAXS) and rheology upon quenching the sample from a disordered state to an ordered state having either spherical or cylindri…
Core and valence band spectra were obtained from a commercial PbO. The XPS data were collected with a VSW HA150 spectrometer equipped with a monochromatic Al Kα x-ray source and a multichannel detector. This report includes the Pb 4f, Pb 5d, Pb 4d, O 1s, C 1s, and valence band photoemission peaks. The XPS analysis sho…
Abstract Six‐membered D,L‐, L,L‐ and D,D‐lactides were polymerized by lipase over a temperature range of 80 to 130 °C to yield the polylactide with a molecular weight ( M w ) of greater than 270000. Among the lipases tested, lipase PS gave the greatest molecular weight of polylactide. The polymerization of D,L‐lactide…
Abstract Amorphous Si 37 C 32 N 31 and Si 37 C 29 N 34 ceramics were produced by pyrolysis of a polyhy-dromethylsilazane precursor. Their structure was investigated by X-ray and neutron diffraction. Wide angle diffraction showed that the Si-atoms are preferentially bonded to nitrogen atoms, but also bonding to carbon…
We have studied antiferroelectricity in twin dimers, in which two mesogens with alkyl tails are linked by an alkylene spacer. Since the conformation of dimers is confined by the spacer, the use of the spacer with an odd carbon number forces the dimer to assume a bent conformation. If a segregation between the spacer a…
The acidic and catalytic properties of the medium pore molecular sieves SAPO-11 and SAPO-31 synthesized by two different routes [from aqueous and nonaqueous (ethylene glycol) media] are compared. Samples synthesized from the nonaqueous medium possess more acidity (due to higher substitution of P 5+ by Si 4+ and conseq…
ZnO additions to BaTiO 3 have been studied in order to determine the role of this dopant on sintering and microstructure development. As a consequence of a better initial dopant distribution, samples doped with 0.1 wt% zinc stearate show homogeneous fine‐grained microstructure, while a doping level of 0.5 wt% solid Zn…
Laser processing of diamond and chemical-vapor-deposited diamond thin films are important in the microelectronics and cutting tool industries because the manufacture of diamond films with low surface roughness and complex shapes has proven to be difficult. In this paper we present a review of current laser polishing a…
Other| April 01, 1998 Reversed determination of the reaction; phlogopite+quartz = enstatite+potassium feldspar+H 2 O in the ranges 750-875 degrees C and 2-12 kbar at low H 2 O activity with concentrated KCl solutions L. Ya. Aranovich; L. Ya. Aranovich University of Chicago, Department of the Geophysical Sciences, Chic…
The models used to describe zinc oxide‐based varistors rely on diffusion and defect data obtained using techniques that have been replaced by more modern methods such as secondary ion mass spectrometry. We report values for oxygen diffusivities in undoped, single‐crystal ZnO as a function of temperature and orientatio…
Bacteria that degrade an aliphatic polycarbonate, poly(hexamethylene carbonate), were isolated from river water in Ibaraki. Prefecture, Japan, after enrichment in liquid medium containing poly(hexamethylene carbonate) suspensions as carbon source, and dilution to single cells. Four of the strains, 35L, WFF52, 61A and…
Previously manufactured oxide dispersion strengthened (ODS) ferritic steel cladding tubes had inferior internal creep rupture strength in the circumferential hoop direction. This unexpected feature of ODS cladding tubes was substantially ascribed to the needle-like grain structure aligned with the forming direction. I…
A theoretical analysis of the experimental bulk modulus Ke of both binary tellurite and binary phosphate glasses containing transition metal oxides V2O5 or MoO3 with different percentages has been done. The main parameters in the analysis were the calculated bulk modulus Kbc and Poisson's ratio σbc. The calculations h…