Materials Literature
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Discotic charge transfer twins, a novel class of discotic liquid-crystalline compounds were studied. These compounds consist of triphenylene units (as donors) which are chemically linked via flexible spacers of various lengths to trinitrofluorenone units (acting as acceptor). They display a liquid-crystalline phase ov…
Studies of the surface composition and CO chemisorption on the [111] and [100] oriented single crystals of the isostructural [face-centered-cubic (fcc)] alloys of bulk stoichiometry Pt3M (M=Ti, Co, and Sn) are reviewed. In principle, the study of these alloys is ideal for separating ensemble effects from electronic ef…
Abstract The CO 2 permeability of uniaxially drawn high‐density polyethylene (HDPE) was investigated and drastic changes were observed as a function of draw ratio. An estimation of variations in both density and fractional free volume of the amorphous component in the drawn polymers was made on the basis of experiment…
Controlled laboratory experimental results of coherent microwave propagation through a random medium are reported. The medium consisted of layers of styrofoam with spherical glass beads embedded at predetermined random positions generated by computer. The magnitude and phase of the transmitted field was measured over…
Glutamate dehydrogenase (GDH) of Clostridium symbiosum, like GDH from other species, is inactivated by pyridoxal 5'-phosphate (pyridoxal-P). This inactivation follows a similar pattern to that for beef liver GDH, in which a non-covalent GDH-pyridoxal-P complex reacts slowly to form a covalent complex in which pyridoxa…
Abstract A series of fluorinated aromatic polyethers was synthesized via aromatic nucleophilic substitution of highly fluorinated aromatics (1,2,4,5‐tetrafluorobenzene, hexafluorobenzene, and decafluorobiphenyl) with bisphenol AF or bisphenol A. Polymerization with 1,2,4,5‐tetrafluorobenzene was not observed, and poly…
Abstract The effects of molecular structure on the dicumyl peroxide crosslinking of two low density polyethylenes have been studied. Peroxide efficiency was determined largely by the content of terminal vinyls in the two polymers. Differences in molecular weight distribution and branch content had comparatively little…
The nature and strength of bonding of carbon dioxide to a high area (136 m2g-1) polycrystalline copper supported on silica has been determined by the combined techniques of Fourier transform infrared spectroscopy (FTIR) and temperature programmed desorption (TPD). These show the room temperature interaction to be init…
The aerobactin operon of the virulence plasmid pColV-K30 of Escherichia coli K12 consists of four genes for biosynthesis and one for transport of the siderophore. Regulation by iron occurs at the transcriptional level and is mediated by a ferrous iron binding protein designated Fur (ferric uptake regulation). The meta…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTBulk semiconductors from molecular solids: a mechanistic investigationW. E. Farneth, N. Herron, and Y. WangCite this: Chem. Mater. 1992, 4, 4, 916–922Publication Date (Print):July 1, 1992Publication History Published online1 May 2002Published inissue 1 July 1992https://pubs.…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCharacterization techniques for the study of silica fragmentation in the early stages of ethylene polymerizationWalter D. Niegisch, Salvatore T. Crisafulli, Tatyana S. Nagel, and Burkhard E. WagnerCite this: Macromolecules 1992, 25, 15, 3910–3916Publication Date (Print):July…
Low-energy electron diffraction, soft x-ray photoemission, cathodoluminescence (CL), and Auger electron spectroscopies have been performed to investigate the geometric, chemical, and electronic properties of GaAs (100) surfaces as a function of annealing temperature and surface reconstruction. These measurements indic…
Abstract Melt blends of nylon‐6/modified ABS (acrylonitrile‐butadiene‐styrene terpolymer) have been prepared using a single screw extruder. Electron microscopic observations revealed that the rubber particles are as finely dispersed as in ABS. Both the heat of fusion and the dynamic storage modulus of the blends were…
The nature of the porphyrin pi-cation radicals in the horseradish peroxidase and bovine liver catalase (BLC) compound I species have been investigated by studying their resonance Raman spectra. A variety of laser excitation and sample interrogation procedures have been employed in order to minimize previously document…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDihydrogen complexes of metalloporphyrins: characterization and catalytic hydrogen oxidation activityJames P. Collman, Paul S. Wagenknecht, James E. Hutchison, Nathan S. Lewis, Michel Angel Lopez, Roger Guilard, Maurice L'Her, Aksel A. Bothner-By, and P. K. MishraCite this:…
The chemisorption and reaction of dichlorosilane (SiH2Cl2) with Si(111) and Si(100) surfaces is investigated with core-level soft x-ray photoelectron spectroscopy employing synchrotron radiation, in order to ascertain the surface chemistry involved in atomic layer epitaxy (ALE). Exposures to 8 kL of SiH2Cl2 were perfo…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNew thermally stable hydroperoxo- and peroxo-copper complexesMohammad Mahroof-Tahir, Narasappa Narasimha Murthy, Kenneth D. Karlin, Ninian J. Blackburn, Shahid N. Shaikh, and Jon ZubietaCite this: Inorg. Chem. 1992, 31, 14, 3001–3003Publication Date (Print):July 1, 1992Publi…
This paper describes experimental studies of the distributions of ligand field sites occupied by ${\mathrm{Cr}}^{3+}$ dopant ions in inorganic glasses with different chemical compositions. The effects of site-to-site disorder are observed via the steady-state spectral band-shape and decay patterns of $^{4}$${\mathit{T…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTInduction of noncentrosymmetry by polar hydrogen-bonded chains in nitroaniline crystalsMargaret C. Etter and Kin Shan HuangCite this: Chem. Mater. 1992, 4, 4, 824–827Publication Date (Print):July 1, 1992Publication History Published online1 May 2002Published inissue 1 July 1…
New relaxation processes are observed in ferroelectric liquid crystals with considerable high spontaneous polarization. These processes are attributed to the formation of ferroelectric domains in FLC cells. The domains have different characteristic periodicities and relaxation times in the bulk of FLC cell and near th…