Materials Literature
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A brown gel was prepared by mixing Zr(OBu n ) 4 and Ce(acac) 3 in anhydrous ethanol. The pyrolysis of this sample was followed under helium flow by online thermogravimetric (TG), gas chromatographic (GC), and mass spectrometric (MS) measurements, to study the conversion of the gel into densified powders. Two different…
X-band EPR spectra of lead titanate (PT) and lead magnesium niobate (PMN) powders prepared by different synthetic methods and a PMN/PT powder of the composition 0.9 PMN/0.1 PT were obtained at 85 and 10 K. Several EPR signals due to adventitious Fe 3+ ion impurities, a signal due to the Ti 3+ ion, and a signal due to…
The adsorption of graft copolymers of poly(acrylamide) (PAAm, backbone) and poly(ethylene oxide) (PEO, side chains) from aqueous solution onto silica and titania was studied with reflectometry. Two high-molar-mass copolymers were used with different PEO graft densities (10 and 18% w/w PEO in copolymers G10 and G18, re…
The reaction order with respect to TiCl 4 was investigated in the living polymerization of isobutylene (IB) initiated by 2-chloro-2,4,4-trimethylpentane (TMPCl)/TiCl 4 in hexane/methyl chloride (Hx/MeCl) 60/40 v/v cosolvents at −80 °C. It was found that the reaction is more complex than previously believed. The TiCl 4…
The reaction of Eu with molten lithium polyselenide produced a new rare-earth dichalcogenide, EuSe 2 . This compound cannot be obtained via direct combination of the elements and is therefore an example of how alkali metal chalcogenide fluxes can access metastable or kinetically stable phases. The crystals of EuSe 2 a…
Having in mind to produce electrically conductive carbon–epoxy composite materials, we have filled an insulating epoxy resin with an electronic conducting polymer, polypyrrole (PPy). To select the PPy that best suits this process, various PPys were chemically synthesized. The syntheses were performed in water via a di…
The response of three commercial fluoropolymer films, untreated and γ-irradiated poly(vinyl fluoride) (PVF), poly(vinylidene fluoride) (PVDF), and poly(ethylene-co-tetrafluoroethylene) (ETFE), to ultraviolet (UV) irradiation was studied. The changes in tensile properties, thermal behavior, and chemical structure were…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTSuzuki Porphyrins: New Synthons for the Fabrication of Porphyrin-Containing Supramolecular AssembliesAlison G. Hyslop, Matthew A. Kellett, Peter M. Iovine, and Michael J. TherienView Author Information Department of Chemistry, University of Pennsylvania, Philadelphia,…
In the present study, low-density polyethylene (LDPE) and plasticized starch (PLST) blends, containing different percentages of PLST, were prepared. In these blends, two different polyethylene/maleic anhydride graft (PE-g-MA) copolymers containing 0.4 and 0.8 mol % anhydride groups, respectively, were added as compati…
We investigated the Rayleigh scattering of silica core optical fibers, parts of which were heat treated at various temperatures, in relation to their fictive temperatures (T(f)). The scattering intensities from short fiber segments were clearly reduced by heat treatment compared with those of the unheated parts. The T…
The photochromic pair 1,1‘-binaphthylpyran ( 1 ) and 2-hydroxy-2‘-hydroxymethyl-[1,1‘]-binaphthylene ( 2 ) was examined to assess suitability as optical triggers in a liquid crystal switch. Both 1 and 2 are chiral and they were resolved into enantiomers by HPLC. The absorption and circular dichroism spectra of optical…
To identify structural features important for low temperature activity in archaeal proteins, elongation factor 2 (EF-2) genes (aef2) were sequenced from psychrophilic, mesophilic and thermophilic methanogens. Scatter plots were used to compare evolutionary distances for EF-2 amino acid sequences vs. 16S-rRNA sequences…
The morphology and self-diffusion in thin films of asymmetric polystyrene- b -2-vinylpyridine (PS−PVP) diblock copolymers were investigated by secondary ion mass spectrometry (SIMS). An oscillatory depth profile of the PVP volume fraction is observed, implying a periodic arrangement of layers of PVP spherical domains…
1 H and 13 C nuclear magnetic resonance (NMR) relaxation studies of thiophenol-capped CdS nanocrystals are presented. The transverse and longitudinal relaxation times were investigated as a function of nanocrystal radius, and the transverse relaxation time was also studied as a function of temperature. Both proton and…
Copper(II)-mediated oxidative coupling of the blue, 18-electron mononuclear complex [Ru II {C 6 H 3 (CH 2 NMe 2 ) 2 -2,6}(terpy)]Cl, 3 (terpy = 2,2‘;6‘,2‘‘-terpyridine), affords the unique diamagnetic, binuclear 34-electron complex [(Ru III ) 2 (4,4‘-{C 6 H 2 (CH 2 NMe 2 ) 2 -2,6} 2 )(terpy) 2 ](CuCl 2 ) 4, 5a . This…
A large number of ternary hydrides of transition metals and alkali or alkaline earth metals have been synthesized and structurally characterized in the last twenty years. These compounds exhibit a puzzling variety of compositions, transition metal coordination numbers, transition metal coordination geometries, and dis…
The effect of inclusion of diarylethenes in cyclodextrin cavities on cyclization quantum yields and on circular dichroism (CD) spectral changes by photoirradiation was studied. The addition of β- and γ-cyclodextrins to an aqueous solution of the open-ring form of 2,2‘-dimethyl-3,3‘-(perfluorocyclopentene-1,2-diyl)bis(…
The electronic and optical properties of (Zn,Mg)(S,Se) wide-gap solid solutions are studied using ab initio techniques and starting from the previously determined atomistic structure of the alloy. Compositional disorder is shown to close substantially the gap with respect to the predictions of the virtual-crystal appr…
Solutions containing KAu(CN) 2 (∼5 × 10 - 4 M), methanol (0.3 M), and nitrous oxide (2.5 × 10 - 2 M) are γ-irradiated in the presence of colloidal gold (∼6 × 10 - 5 M; mean particle size, 15 nm). The hydroxymethyl radicals, • CH 2 OH, which are generated in these solutions, reduce Au(I) in Au(CN) 2 -, and the reduced…
Strong and sustained electron emission at low electric fields was observed in undoped, nanostructured diamond. Electron emission of 10 milliamperes per square centimeter was observed at applied fields of 3 to 5 volts per micrometer. These are the lowest fields ever reported for any field-emitting material at technolog…