Materials Literature
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Abstract The effects of ion irradiation in the ABO 4 -type compounds were compared by performing experiments on four materials that include the most common crystal structures (monazite vs. zircon) and chemical compositions (phosphates vs. silicates) for these phases. Pure synthetic single crystals of ZrSiO 4 , monocli…
A novel sensor based upon surface-enhanced Raman scattering (SERS) has been constructed by immobilizing colloidal silver particles onto the distal end of an optical fiber. This same single fiber was then used to both transport the exciting laser radiation and collect the Raman scattering from analytes sorbed onto the…
The morphology and behaviour of the chromosomes of dinoflagellates during the cell cycle appear to be unique among eukaryotes. We used synchronized and aphidicolin-blocked cultures of the dinoflagellate Crypthecodinium cohnii to describe the successive morphological changes that chromosomes undergo during the cell cyc…
We describe a pulsed spectrometer for detection of nuclear quadrupole resonance on the nuclei of nitrogen N-14 with fast Fourier transform. The use of a multipulse sequence, four channel system for data registration and processing permits detection of the nuclear quadrupole resonance (NQR) signal in the presence of st…
Abstract Hydrothermal syntheses were performed at various pH values and temperatures to induce variability in kaolinite defect density. Temperature of synthesis ranged from 200 to 240°C, for 21 d. Initial pH at room temperature ranged from 0.5 to 14. The starting material was a hydrothermally treated gel, with an atom…
The isothermal oxidation of the 200 face of HfC and TiC single crystals was performed at temperatures of 700°—1500°C and at oxygen pressures of 0.08—80 kPa for 4 h. The weight gain by oxidation of the two crystals was followed using an electromicrobalance. A polished cross section of the oxidized crystals was observed…
A gene (pueA, polyurethane esterase A) encoding an extracellular polyurethanase (PueA) was cloned from Pseudomonas chlororaphis into Escherichia coli. The enzyme secreted from E. coli showed esterase activity when assayed with p-nitrophenyl acetate. Subcloning of a 3. 2-kb SalI-EcoRI fragment into a T7 RNA polymerase…
One of the many forms of carbon, diamondlike carbon (DLC) or tetrahedral amorphous carbon (ta-C) consists mainly of sp3 bonded carbon atoms. If properly prepared, DLC can have properties that rival those of crystalline diamond. The beneficial properties of DLC stem from the continuous rigid random networks of sp3 carb…
The rates for nucleation ( I ) and crystal growth ( U ) for a lithium disilicate (Li 2 O·2SiO 2 , LS 2 ) glass were determined, as a function of temperature, using a new differential thermal analysis (DTA) technique. This technique requires in situ nucleation and crystal‐growth heat treatment of a small amount of powd…
CeO 2 ultrafine particles were prepared by solid‐state reactions at room temperature. These particles were found to have very fine particle sizes (∼3 nm) with a fluorite structure ( a = 5.42 Å). BET measurements showed that the surface area of the particles was 96.2 m 2 /g. The use of two different precursors was foun…
We describe a microfabrication process for fabricating micropolarizer devices with polarization thin film. The polarization film is less than a 0.5 microm thick and can have a polarization extinction ratio of approximately 330 in the visible wavelength range. A single-state micropolarizer array with polarizing pixels…
AbstractThe effects of partial substitution of tungsten for molybdenum on the microstructure and impact properties in 22Cr–5Ni–3Mo (wt-%) duplex stainless steel (DSS) have been investigated following aging heat treatments in the temperature range 600–1000°C. During aging the intermetallic σ and χ phases were precipita…
The gene encoding the phosphoglycerate kinase (PGK) from the Antarctic Pseudomonas sp. TACII18 has been cloned and found to be inserted between the genes encoding for glyceraldhyde-3-phosphate dehydrogenase and fructose aldolase. The His-tagged and the native recombinant PGK from the psychrophilic Pseudomonas were exp…
Neutron-diffraction, magnetic and transport measurements, and M\"ossbauer spectroscopy have been used in order to study the structural and magnetic changes of the magnetoresistive ${\mathrm{La}}_{0.7}{\mathrm{Pb}}_{0.3}{\mathrm{Mn}}_{1\ensuremath{-}x}{\mathrm{Fe}}_{x}{\mathrm{O}}_{3}$ $(x=0,$ 0.05, 0.1, 0.2, 0.3) pero…
This paper presents a dynamic model allowing the prediction of discharge activity leading to flashover of polluted insulators. It takes into account the instantaneous changes of the discharge (arc) parameters. For a given voltage, geometry and pollution severity, the model enables one to determine the following parame…
Abstract The work described in this paper deals with the preparation and the characterization of an homogeneous composite material composed of electrically conductive fillers dispersed in a thermoplastic insulating matrix. These fillers were chosen to have either a spherical shape or a high aspect ratio. Processing of…
[1]Silaferrocenophanes fcSiMe 2 ( 1 ) and fcSi(CH 2 ) 3 ( 3 ) (fc = Fe(η 5 -C 5 H 4 ) 2 ) were incorporated into the well-ordered, hexagonal channels of mesoporous silica (MCM-41). Characterization of the composite materials indicates the presence of ring-opened monomer, oligomer, and polymer, and, in the case of 1, a…
The electrochemical behavior of conducting polyaniline coatings on various aluminum alloys subjected to immersion in dilute Harrison solution (0.35% ammonium sulfate [(NH4)2SO4], 0.05% sodium chloride [NaCl]) was studied. Electrochemical impedance spectroscopy revealed that the charge-transfer resistance (Rct) of poly…
High resolution transmission electron microscopy is used to image the nanostructure of ultrafine ferroelectric lead titanate particles ranging from 20 to 2000 nm in diameter. The crystal structure, surface morphology, domain–wall structure, as well as surface reconstruction under a 400 KeV electron beam are studied. H…
The intramolecular cyclization in hyperbranching polycondensation reactions of the type AB2/Bf was investigated both theoretically and experimentally. Hyperbranched aliphatic polyesters prepared from 2,2-bis(hydroxymethyl)propionic acid (BisMPA) and 1,1,1-tris(hydroxymethyl)propane (TMP) as B3 core molecule as well as…