Materials Literature
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This Test Guideline describes the Zahn-Wellens/EMPA Test. It is used to determine inherent biodegradability. A mixture containing the non-volatile and water soluble test substance, mineral nutrients and a relatively large amount of activated sludge in aqueous medium is agitated and aerated at 20-25°C in the dark or i…
A technique enabling the study of adherence occurring among implant materials and epithelial and connective cells cultured in vitro and freshly obtained from explants of human gingival tissue is described. The data show that cell adherence to titanium alloy is influenced by the modality of implant surface preparation.
The wettability of eight nonaqueous elastomeric impression materials was studied by comparing their contact angles. The materials included three polyethers (one of which was light activated), three hydrophilic poly(vinyl siloxanes), one conventional poly(vinyl siloxane), and one poly(vinyl siloxane) putty. Extracted t…
Thin films of the organic semiconductor copper phthalocyanine (CuPc) are deposited onto glass substrates maintained at room temperature, and their structures investigated using X-ray diffractometry and infrared light absorption. Films of thicknesses approximately 0.1 μm are preferentially oriented in the [001] directi…
Cristallisation dans P4/ncc avec a = 7,447 et c = 16,138 A, Z = 4; affinement jusqu'a R = 0,023. La structure est du type BaFe[Si 4 O 10 ]. Elle contient des tetraedres SiO 4 qui partagent des sommets pour former des cycles a 4 membres qui a leur tour forment des couches Si 8 O 20 . Les cations Ba et Cu sont localises…
We have investigated the polar-angle dependence of medium-energy electron diffraction (MEED) from a Cu(100) surface. It is observed that MEED is characterized by a combination of coherent and incoherent scattering, and the incoherent part is governed by the forward-scattering mechanism. The incoherent MEED pattern dif…
In this paper we have subjected different layered transition-metal dichalcogenides to scanning tunneling microscopy to reveal the electronic charge distribution associated with the charge-density-wave (CDW) part of the superstructure, in addition to the atomic corrugation. The observations presented display three regi…
The lifetime of indirect excitons in AgBr quantum dots was studied at low temperature. Indirect-exciton luminescence shows a nonexponential decay. The unique nonexponential decay is well explained by a model that takes into account the discrete number of iodine impurities in a AgBr quantum dot. The obtained radiative…
Abstract Boron, aluminum, and gallium tristriflate are new effective catalysts for the polymerization of tetrahydrofuran (THF). High‐molecular‐weight polytetrahydrofuran (PTHF) was obtained in excellent yield in the bulk polymerization of THF at ambient temperature with all three catalysts. The PTHF samples were chara…
Highly correlated electronic structure calculations using many-body perturbation theory (MBPT) and coupled-cluster (CC) gradient techniques are applied to a study of a reaction pathway which links the two forms [C2v and D2d ] of diborane(4) [B2H4]. A reaction coordinate which preserves C2 symmetry is studied, as this…
The yeast fatty acid synthase (M(r) = 2.5 x 10(6)) is organized in an alpha 6 beta 6 complex. In these studies, the synthase structure has been examined by negative-stain and cryo-electron microscopy. Side and end views of the structure indicate that the molecule, shaped similar to a prolate ellipsoid, has a high-dens…
The sample length of the charge-density-wave (CDW) conductor ${\mathrm{TaS}}_{3}$ is found to be a sensitive function of the applied dc bias electric field E and time t. The length reflects transitions through metastable CDW configurations for both the pinned and sliding CDW in the presence of random impurities. Altho…
The magnetoresistance of single-crystal graphite has been measured at low temperatures in pulsed high magnetic fields up to 52 T applied parallel to the c axis. Many features were found in the high-field phase after the field-induced electronic phase transition. After the sharp rise at the phase transition, the resist…
We present a model of the electronic density of states (DOS) for a wide class of ternary and quaternary semiconductor alloys. Our approach is based on a large-cluster calculation using a semiempirical tight-binding model for the electronic structure. The microscopic lattice configuration is efficiently determined by a…
Cristallisation dans P2 1 /c avec a = 6,292, b = 12,329 et c = 9,233 A, β = 105,91 °, Z = 2; affinement jusqu'a R = 0,030. La structure consiste en cations et en anions maintenus ensemble par des liaisons hydrogene impliquant tous les atomes H excepte un H appartenant au groupe ammonium. Coordination octaedrique pour…
Abstract Tannin beads formed by reaction of Mimosa tannin (condensed‐type tannin) with formaldehyde in nonpolar polybutenous medium were microspherical resins. Resins prepared with 37.5% tannin concentration were porous spherical resins with 139.22 m 2 /g of surface area (adsorption method of iodine in n ‐hexane, 2.1…
The absorption spectra due to the 4 f →5 d transitions in Ce 3+ centres have been measured with the use of YAG:Ce 3+ single crystals with a lattice concentration [Ce 3+ ] L =(1.28±0.05)%. The data are almost independent of the spectral behaviour of a reference spectrum whose absorption constants are ∼2 cm -1 at the hi…
Photoemission data in which the signal from the first atomic layer is well resolved from that of the bulk are used to determine accurately the kinetic-energy dependence of the inelastic-electron mean free path in the alkali metals. At the higher kinetic energies, the data are in very good agreement with the theory of…
We present photoluminescence and transmission measurements of vapor-grown GaTe crystals. The ground-state 1S triplet and singlet excitonic peaks are well resolved in the optical photoluminescence spectra from high-quality crystals, the triplet state lying \ensuremath{\sim}1.6 meV lower in energy than the singlet state…
The two-particle correlation function is related to the structure factor by an integral transform and serves as an important connection between suspension microstructure, scattering experiments, and macroscopic properties. The nonequilibrium structure factor for a shearing colloidal suspension of spherical particles i…