Materials Literature
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We use transient optical hole burning and photoluminescence to investigate the static and dynamic electronic properties of 32-\AA{} CdSe quantum dots. We observe a number of discrete electronic transitions, resolve LO-phonon progressions, and obtain homogeneous linewidths and electron--LO-phonon couplings. We find tha…
It was found that two different crystal forms, namely a platelike α-form and a hairlike β-form, were obtained by cooling crystallization of quizalofop-ethyl dissolved in ethyl alcohol. The solubilities, supersolubility and stabilities of the two crystals were investigated. Two solubility curves for the α-form and the…
The aqueous preparation of supported niobium oxide catalysts was developed by using niobium oxalate as a precursor. The molecular states of aqueous niobium oxalate solutions were investigated by Raman spectroscopy as a function of pH. The results show that two kinds of niobium ionic species exist in solution and their…
Crystallization from solution is an important separation and purification process in a wide variety of industries. These range from basic materials such as sucrose, sodium chloride and fertilizer chemicals to pharmaceuticals, catalysts and specialty chemicals. The major purpose of crystallization processes is the prod…
Ribonuclease H digests the RNA strand of duplex RNA.DNA hybrids into oligonucleotides. This activity is indispensable for retroviral infection and is involved in bacterial replication. The ribonuclease H from Escherichia coli is homologous with the retroviral proteins. The crystal structure of the E. coli enzyme revea…
The bacterial tryptophan synthase bienzyme complexes (with subunit composition alpha 2 beta 2) catalyze the last two steps in the biosynthesis of L-tryptophan. For L-tryptophan synthesis, indole, the common metabolite, must be transferred by some mechanism from the alpha-catalytic site to the beta-catalytic site. The…
Using the boundary-integral formulation, we show that the fully isotropic model of eutectic growth in directional solidification supports solutions with a broken parity symmetry. These correspond to the tilted ``waves'' observed recently by Faivre et al. Our results are in good agreement with these experiments. For a…
The complete amino-acid sequence of the bovine olfactory epithelium adenosine 3',5'-cyclic monophosphate (cAMP)-gated channel has been determined by cloning and sequencing its cDNA. It exhibits a high degree of sequence homology with the cGMP-gated channel of rod photoreceptors, suggesting that cyclic nucleotide-gated…
Diamond (100) substrates have been fluorinated under ultrahigh vacuum conditions with both atomic and molecular fluorine. X-ray photoelectron spectra of the resulting samples indicate that atomic fluorine, F, reacts efficiently at 300 K producing a saturation coverage of about three quarters of a monolayer (one monola…
The variations of the electrical resistivity, the magnetization, and the grain boundary precipitates of a binary NiSn alloy system with Sn content up to 8 at% are investigated as functions of the annealing time at 773 K. For samples homogenized at 1325 K, clear grain boundaries are observed; the residual electrical r…
The influence of the substituents on the prefiring conditions of nickel ferrites from the system Nix1Cux2Cox3Znx4Mnx5Alx6Fex7O4 where 0.14 ≤ x1 ≤ 1;0 ≤ x2 ≤ 0.3; 0 ≤ x3 ≤ 0.06; 0 ≤ x4 ≤ 0.5; 0 ≤ x5 ≤ 0.06; 0 ≤ x6 ≤ 0.2; 1.8 ≤ x7 ≤ 2.1 is investigated. It is found that the prefiring conditions influence the resonance l…
Solid solutions of magnesium ferrite and magnesium titanate are prepared by ceramic technique from α-Fe2O3, TiO2, and magnesium oxalate by heating at high temperature followed by quenching or by slow cooling. The compounds crystallise in monophasic cubic spinel structure. The compounds are studied for their initial su…
The effect of heat treatment on the magnetic properties and microstructure of (Nd, Dy)–(Fe, Co)–B based sintered magnets with small additions of alloy elements are investigated. It is found that the magnetic properties of these magnets are almost unchanged by heat treatment at 900°C (T1), which is useful for relieving…
A series of oxyhalogenide 30 SiO2–55 PbO–15 Pb(F1−xClx)2 (0 ≥ x ≥ 1) glasses belonging to the quaternary SiO2PbOPbF2PbCl2 system are prepared. A study of the electrical properties of these materials allows to prove the existence of a mixed mobile ion (MMI) effect in these anion-conducting glasses over the whole mix…
Internal friction measurements at constant frequency are useful in determining the liquid–glass transition of non-crystalline materials that devitrify easily or when the number of available configurations are entropically not sufficiently high to develop a neat endotherm at Tg. This method is applied to oxide glasses…
ESR and photo-ESR measurements of the V centre are performed to determine the charge states of the oxygen vacancies in ZnO raw material and Li-doped ZnO ceramics. The temperature dependence of the relative ESR intensity and the optical excitation of the ESR signal of the V centre are investigated. The results show, th…
Cristallisation dans P4/nmm avec a=4,696, c=7,559, Z=2; affinement jusqu'a R=0,0223. La structure est caracterisee par des couches de tetraedres ∞ 2 [NaS − 4/4 ], separees par des couches doubles de Rb, pour former une geometrie de type PbFCl
β-Pb 0,333 V 2 O 5 cristallise dans C2/m avec a=15,463, b=3,6477, c=10,116 A, β=109,20 o , Z=6; affinement jusqu'a R=0,054. La structure est du meme type que celle de β-Na x V 2 O 5 . Du fait du desordre monodimensionnel des chaines decalees d'ions Pb le long de [010], des reflexions du sous-reseau apparaissant a h/2,…
Cristallisation dans Cmcm avec a=3,6784, b=11,6120, c=18,6332 A, Z=8; affinement jusqu'a R=0,041. Des octaedres VO 6 deformes sont lies pour former des couches V 2 O 5 paralleles a (001). Des ions K sont situes entre les couches, entoures par 8 atomes O, et sont dans un miroir au parallele a (001)
The oxidation of the GaAs(110) surface with ${\mathrm{NO}}_{2}$ has been studied by Fourier-transform infrared spectroscopy, molecular-beam techniques, and transport measurements. We find that ambient ${\mathrm{NO}}_{2}$ dissociatively adsorbs with an average low-coverage probability of 0.03 at room temperature and 0.…