Materials Literature
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The microscopic description of spin-Peierls substances is discussed. Particular attention is paid to the ordered (dimerised and incommensurably modulated) phases. Important points are the adiabatic and the antiadiabatic approach, generic soliton forms, elastic and magnetic interchain couplings. The wealth and the accu…
ZnO/Mg 0.2 Zn 0.8 O superlattices with a band-gap offset of about 0.5 eV were epitaxially grown by laser molecular-beam epitaxy on a sapphire(0001) substrate using a ZnO buffer layer. The superlattice structure with a period ranging from 8 to 18 nm was clearly verified by cross-sectional transmission electron microsco…
The effect of stearic acid concentration on the reversion behavior of epoxidized natural rubber (ENR 25 and ENR 50) was carried out in the temperature range of 150–180°C and 0.5–14.5 phr of stearic acid loading. Three common accelerators; namely, zinc dimethyldithiocarbamate (ZDMC), tetramethylthiuram disulfide (TMTD)…
The cation of the title compound, CI3HI4N~--C4H506-.H20, has a central guanidinium fragment with a planar geometry, as expected for sp 2 hybridization at the C atom. The conformation of the phenyl rings is syn-syn with respect to the unsubstituted N atom, but the overall conformation of the cation is far from the C2v…
Barium hexaferrite (BaM) thin films were deposited on (0001) LiTaO3 substrates by pulsed laser deposition. Effects of the substrate temperature and oxygen gas pressure on the formation and quality of these films were studied. Films deposited at a substrate temperature of 800 °C and an oxygen pressure around 0.23 mbar…
We have measured the photon-energy dependence of the $\mathrm{O}1s2s2s$ and $\mathrm{O}1s2s2p$ resonant Auger lines at the $\mathrm{O}K$ edge of NiO. The transition from the Raman-like regime, where these features are observed at constant binding energy, to the Auger regime, where they appear at constant kinetic energ…
High molecular weight carboxylated polybutadienes (cPBDs) with number-average molecular weight (Mn) from 98,000 to 200,000 and carboxylic acid (COOH) contents of 0.5–10 mol % were successfully synthesized through hydrocarboxylation of polybutadienes (PBDs) at temperatures of 140–150°C using PdCl2(PPh3)2 and SnCl2 · 2H…
In an attempt to view the onset of urea denaturation in ribonuclease we have collected X-ray diffraction data on ribonuclease S crystals soaked in 0, 1.5, 2, 3, and 5 molar urea. At concentrations above 2 M urea, crystals were stabilized by glutaraldehyde crosslinking. We have also collected data on ribonuclease S cry…
The crystal and magnetic structures of the system YFe11−xCoxTi have been investigated by high-resolution neutron powder diffraction for the compositions x=1, 3, 7, and 9. All compounds have the ThMn12 type structure, with space group symmetry I4/mmm. The distribution of the atoms over the independent crystallographic…
Thermal analysis based on TGA (thermal gravimetric analysis) and DSC (differential scanning calorimeter) shows no significant degradation for PVDC which has been annealed at 210°C for less than 2 min. And the following recrystallization behavior at lower temperature (120°C) is also independent of the thermal treatment…
This article describes the synthesis and the properties of polyesters and copolyesters prepared from ethylene glycol, terephthalic acid, 4,4′ biphenyldicarboxylic acid (BDA), and 2,6-naphthlenedicarboxylic acid (NDA). The effect of incorporating varying levels of BDA and NDA on polyethylene terephthalate (PET) is desc…
We have systematically studied the evolution of the optical properties of free-standing porous silicon (PS) films during thermal oxidation at 200 °C in air by measuring of the PL, IR, optical absorption and Raman scattering spectra. After thermal oxidation for 200 h, the PL peak energies of free-standing PS films focu…
In this work a complete valence-band structure of $\ensuremath{\alpha}\ensuremath{-}{\mathrm{MoTe}}_{2}$ using angular-resolved photoelectron spectroscopy (ARPES) with synchrotron radiation is presented. The dispersion along the perpendicular component ${k}_{\ensuremath{\perp}}$ of the wave vector is found to be non-n…
We did directional solidification experiments on Fe20Nd80 alloys at several low cooling rates in order to observe the solidification sequence, displayed along the length of the sample. We also took measurements of the transition temperatures around the eutectic temperature using a Calvet type calorimeter. Our results…
Inactivation of the Escherichia coli gene ydeA, which encodes a member of the major facilitator superfamily, decreased the efflux of L-arabinose, thereby affecting the expression of AraC-regulated genes. In addition, overexpression of ydeA decreased the expression of genes regulated by isopropyl-beta-D-thiogalactopyra…
Four series of photocrosslinkable-cum-flame retardant poly(benzylidene phosphoramide ester)s were synthesized from bis(4-hydroxy-3-methyoxybenzylidene) acetone, 2,5-bis(4-hydroxy-3-methoxybenzylidene)cyclopentanone, 2,6-bis(4-hydroxy-3- methoxybenzylidene)cyclohexanone and 2,7-bis(4-hydroxy-3-methoxybenzylidene) cyclo…
We have measured the temperature dependence of the absorption spectra in the band-edge region and the reflection spectra of the (CH 3 NH 3 ) 3 M 2 Br 9 (M:Sb,Bi) single crystals exhibiting serveral successive phase transitions. The dispersion-like reflection structure due to the band-edge exciton transition is observe…
Time-resolved photoluminescence measurements are performed on oxidized and fresh porous silicon at room temperature. Comparing the evolution of the nanosecond time-delayed photoluminescence (PL) in both cases, a new feature of the PL spectra is identified: a fast red band, present both in fresh and aged samples. The n…
The rhombohedral Pr2Fe17Hx compounds with the Th2Zn17 structure have been prepared for x=0–5. Their lattice parameters and Curie temperatures have been determined from powder x-ray diffraction and thermomagnetic measurements, respectively, and their Mössbauer spectra have been measured between 4.2 and 295 K. The Mössb…
The microwave heating technique is employed for obtaining high performance positive temperature coefficient of resistivity (PTCR) ceramics of Nb-doped BaTiO3 with a low resistivity at room temperature and a high resistivity jump above the Curie temperature. The grains of the BaTiO3:Nb ceramics prepared by microwave si…