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Rheometrische und tensi ometrische Untersuchungen an lösemittelarmen Lackharzlösungen / Rheometric and Surface Energy Characterization of Varnish Resin Soluti ons with Low Solvent Content
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AULACOSEIRA SKVORTZOWII SP. NOV. (BACILLARIOPHYTA), A POORLY UNDERSTOOD DIATOM FROM LAKE BAIKAL, RUSSIA1
ABSTRACT Aulacoseira skvortzowii sp. nov. is a diatom taxon present in modern plankton assemblages and sedimentary deposits from Lake Baikal, Russia. It has been previously reported as A. islandica (O. Müll.) Simonsen, A. islandica ssp. helvetica (O. Müll.) Simonsen, a sporangial frustule of A. baicalensis (K. Meyer)…
Effect of the Composition of Polypyrrole Substrate on the Electrodeposition of Copper and Nickel
Electrodeposition of copper and nickel on a variety of substrates including conductive polymer films with two different compositions has been studied. The enhancement of the copper and nickel electrodeposition rate was observed for composite polypyrrole films with cation‐exchange properties in comparison to undoped po…
Anionic polymerization of oxirane in the presence of the polyiminophosphazene base t‐Bu‐P4
Abstract The use of the polyiminophosphazene base t ‐Bu‐P 4 (1) for the anionic polymerization of ethylene oxide is described. Polymerization initiated by a monoalkoxide of the protonated base leads to well‐defined poly(ethylene oxide)s with low polydispersity ( M w / M n ≈ 1.1). Furthermore, graft copolymers of poly[…
A single source approach to the synthesis of CdSe nanocrystallites
Synthetic routes to semiconductor nanocrystallites have become of particular interest since nanoparticle devices have been constructed. The route reported here for CdSe uses a single source in tri‐ n ‐octylphosphine oxide instead of the hazardous metal alkyls conventionally employed. The characterization of the nanocr…
Determination of the centroid or `the best centre' of a coordination polyhedron
The geometric parameters related to the point in the coordination polyhedron having the minimum variation of distances to the vertices (`the centroid of the coordination polyhedron') are proposed as a measure of polyhedral irregularity or deformation. The numerical method for the determination of the centroid coordina…
Some Nonionic Surfactants as Inhibitors of the Corrosion of Iron in Acid Chloride Solutions
The inhibition effect of the surfactants 1,2-hexanediol (HD), 1,2,3-octanetriol (OT); 1,2,3-nonanetriol (NT); and 3,7-dimethyl-1,2,3,6,7-octanepentol (DOP) on the corrosion of iron in 1 M hydrochloric acid (HCl) was studied. Results obtained from gravimetric methods showed inhibition efficiencies increased with increa…
EFFECTS OF HARVEST STAGE AND LIGHT ON THE BIOCHEMICAL COMPOSITION OF THE DIATOM THALASSIOSIRA PSEUDONANA1
ABSTRACT The marine diatom Thalassiosira pseudonana (Hustedt, clone 3H) Hasle and Heimdal was cultured under three different light regimes: 100 μmol photon · m −2 · s −1 on 12:12 h light : dark (L:D) cycles; 50 μmol photon · m −2 · s −2 on 24:0 h L:D; and 100 μmol photon · m −2 · s −1 on 24:0 h L:D. It was harvested d…
A new model for {1012} twin growth in hcp metals
Computer simulation has been used to study the interaction of a perfect, basal dislocation with a {1012} twin boundary in a hcp metal for the situation where the 1/3{1120} Burgers vector is inclined at 60° to the interface. It is found that slip is not transferred from one crystal to the other with a residual dislocat…
An Improved Mean Atomic Number Background Correction for Quantitative Microanalysis
Quantitative EPMA (electron probe microanalysis) intensity measurements require an accurate correction for the X-ray continuum (or background) created by the Bremsstrahlung effect from the primary electron beam. This X-ray continuum, as measured on a wavelength-dispersive spectrometer at any particular wavelength, is…
The Correction for Attenuation
This article examines the statistical correction for attenuation and the controversies surrounding the procedure. Although originally developed for test construction purposes, the correction for attenuation is also used in meta-analysis and assessments of validity generalization. Since Spearman's classic article in 19…
Size-Dependent Colors and Luminescences of Organic Microcrystals
Perylene microcrystals with different sizes from about 50 nm to about 200 nm were prepared using the reprecipitation method. Their excitonic absorption peaks were found to shift to the high energy side with decreasing crystal size, that is to say, the shifts from that of the bulk crystal were about 500 cm -1 and 1420…
Spin-state transition and high-spin polarons in LaCoO3
The spin gap energy (\ensuremath{\approx} 30 meV) associated with the low-spin ($S=0$) to high-spin ($S=2$) transition in LaCo${\mathrm{O}}_{3}$ was proved to be considerably smaller than the charge gap energy (\ensuremath{\approx} 0.1 eV) which was estimated by optical spectroscopy. Hole doping in the low-spin ground…
Powder diffraction
The powder diffraction method, by using conventional X-ray sources, was devised independently in 1916 by Debye and Scherrer in Germany and in 1917 by Hull in the United States. The technique developed steadily and, half a century later, the `traditional' applications, such as phase identification, the determination of…
Local elastic expansion model for viscous-flow activation energies of glass-forming molecular liquids
A model for the viscosity of glass-forming molecular liquids is proposed in which a ``flow event'' requires a local volume increase. The activation energy for a flow event is identified with the work done in shoving aside the surrounding liquid; this work is proportional to the high-frequency shear modulus, which incr…
Oxygen Vacancy Motion in Perovskite Oxides
Using electron paramagnetic resonance, the motion of oxygen vacancies within the oxygen octahedron in perovskite BaTiO 3 is observed via the alignment of oxygen vacancyrelated defect dipoles induced by bias/heat combinations. The vacancy motion is found to have an activation energy of 0.91 eV, in excellent agreement w…
Anomalously high entropy change in FeRh alloy
The temperature dependences of heat expansion, elastocaloric effect, magnetocaloric effect, and the shift in the critical temperature of the transition due to tensile stress have been measured using samples of the same concentration Fe49Rh51 in the antiferromagnetic-ferromagnetic (AF-F) transition range. Using data on…
High-temperature heat capacity and thermal expansion ofSrTiO3andSrZrO3perovskites
The heat capacity and thermal expansion of ${\mathrm{SrZrO}}_{3}$ and ${\mathrm{SrTiO}}_{3}$ have been determined by drop calorimetry and energy-dispersive x-ray diffraction from 300 up to 1800 K or more. For both compounds, thermal history has a slight influence on relative enthalpies in the range 900--1400 K but a s…