Materials Literature
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Fast and temperature-stable emission band at 5.8 EV has been reveadled in a K2SO4 crystal. This emission can be effectively excited by photons of hv > 15 eV and is interpreted as radiative electron transitions between the subbands of a splitted valence band. The threshold of the formation of electron-hole pairs equals…
Electron and neutron irradiation of diamond produces a wide variety of different EPR defect centres. The definitive establishment of the vacancy (neutral and negatively charged), the nearest neighbour di-vacancy (R4/W6) and a nearest neighbour pair of ⟨100⟩ split interstitials (R1) form some starting points, from whic…
Ethylene-propylene-diene terpolymer rubberlnatural rubber blends (EPDM/NR) in different proportions (100 : 0, 75 : 25, 50 : 50, 25 : 75, and 0 : 100) reinforced with 20 phr semireinforcing furnace carbon black have been studied. The permittivity ∊' and dielectric loss ∊″ for these samples were determined in the freque…
One-step preparation of composites of alkaline poly(6-hexanelactam) (PCL) with solid lubricants (SL), such as graphite and molybdenum disulfide, is an energy-saving process as additional polymer fusion and melt mixing are not necessary. The initiator/activator system used were: (i) sodium dihydrido-bis(2-methoxyethoxo…
A simple method is reported for preparing gold nanoparticles capped with 3-mercaptopropionic acid(MPA). The capped Au nanoparticles can be isolated as a dark brown solid which can be re-dispersed in sodium hydrate solution. The average size of nanoparticles is 4.9 ± 0.7 nm, determined by HRTEM. The surface plasmon ban…
Photochemical charge transfer excitation of tetra-phenyl(porphyrinato)iron(III) complexes yields tetraphenyl) (porphyrinato)iron(II) which is able to coordinate molecular oxygen under formation of oxo-[tetraphenyl(porphyrinato)]- iron(IV). Based on this photochemical reaction pathway photocatalytic oxygenation of α-pi…
Visible electroluminescence (EL) from n‐type porous silicon (n‐PS) in an electrolyte solution containing was investigated by potential‐sweep and potential‐step methods. Potential sweep measurements showed that both the cathodic current and EL intensity increased and the EL spectra blue‐shifted as the potential became…
Standard periphyton samplers were used to examine the colonization pattern of periphytic algae on an artificial substrate (glass slides) in the Lam Tsuen River, Hong Kong, between October 1995 and August 1996. Changes in the taxonomic composition, species diversity (Shannon-Wiener diversity index), total standing crop…
We demonstrate how the mathematical treatment of the switching current data allows to characterize the variation of the domain structure during fatigue. Investigating PZT/YBCO heterostructures on SrTiO3 and NdGaO3 substrates we propose two different scenarios of fatigue-induced evolution of the domain structure. The e…
The magneto-thermoelectric power (TEP) $\ensuremath{\Delta}S(T,H)$ of perovskite-type manganese oxide ${\mathrm{La}}_{0.6}{\mathrm{Y}}_{0.1}{\mathrm{Ca}}_{0.3}{\mathrm{MnO}}_{3}$ is found to exhibit a sharp peak at some temperature ${T}^{*}=170 \mathrm{K}.$ By approximating the true shape of the measured magneto-TEP i…
Graphite has normally been used to synthesise fullerenes and nanotubes. However, coal is a cheaper and more suitable industrial material. Because coal is a molecular solid, unlike graphite, the mechanism by which fullerene and nanotubes are formed is different. Moreover, other products such as polyaromatic hydrocarbon…
Abstract The tensile strengths, σ b , and apparent fracture energies, G , of edge-cut strip specimens (28 mm wide) of carbon black-filled vulcanizates of natural rubber (NR), cis -butadiene rubber ( cis -BR), and a 50/50 blend have been determined. The BR vulcanizate exhibited a rather steady decrease in σ b with incr…
A ferroelectric phase transition is observed in Langmuir-Blodgett films prepared from substituted copper phthalocyanine molecules. The linear and nonlinear dielectric properties of the films and the switching of their spontaneous polarization are investigated in the temperature range of the phase transition. The obser…
KDN (2-keto-3-deoxy-D-glycero-D-galacto-nononic acid), a sialic acid analog, has been found to be widely distributed in nature. Despite the structural similarity between KDN and Neu5Ac, alpha-ketosides of KDN are refractory to conventional sialidases. We found that the hepatopancreas of the oyster, Crassostrea virgini…
The stability of the aromatic phase of two-dimensional monolayers of BN, C, Si, GaAs, and SiC is theoretically investigated using an ab initio tight-binding-like method. It is found that BN, C, and SiC prefer to form the flat aromatic phase while Si and GaAs prefer to pucker, although Si is found to be a borderline ca…
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X-ray diffraction studies of ammonium myristate and palmitate show crystals that belong to space group P 2 1 / n with the methylene groups packing in a triclinic subcell. The infrared spectra of the palmitate and stearate are similar as expected, but the bands of the myristate salt show additional splitting in the met…
A new series of N 2 O tridentate ligands HL n ( n = 2−5) have been prepared through N -methylation or N -benzylation of 2- N -(2-pyridylmethyl)aminophenol (HL 1 ). Treatment of these ligands with WO 2 Cl 2 (DME) (DME = 1,2-dimethoxyethane) in the presence of triethylamine leads to the formation of cis -dioxotungsten(V…
This paper presents a characterization study of the microstructural evolution of various carbon fibre-reinforced polycarbosilane (PCS)-derived SiC matrix composites during high temperature heat treatment. Both surface-treated and untreated carbon fibre reinforcements were investigated. The STEM/EELS technique was foun…
The crystallization of stoichiometric barium osumilite (BaMg 2 Al 6 Si 9 O 30 ) glass manufactured by melting or by sol‐gel processing using an all‐alkoxide route (AAR) or a partial‐alkoxide route (PAR) using mixed alkoxides and salts has been characterized by thermal methods, phase analysis, and microstructural analy…