Materials Literature
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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[…
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…
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…
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…
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…
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…
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…
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…
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…
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…
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…
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…
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…
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…
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…
Aspects of the ultrastructural interaction between collagen and mineral crystals in embryonic chick bone have been examined by the novel technique of high voltage electron microscopic tomography to obtain three-dimensional information concerning extracellular calcification in this tissue. Newly mineralizing osteoid al…
We have studied the temperature dependence of dielectric relaxation times in terms of the peak frequency fmax(T) of dielectric loss ε″(ω) and the dc-conductivity σdc(T) of several glass-forming liquids, covering 12 decades in the peak frequency fmax and 9 decades in σdc. Although dc-conductivity samples the mobility o…
Direct electrodeposition of zinc oxide films is reported for the first time. That this method of preparation is suited to large‐scale production could be important for applications of ZnO, e.g., in solar cells. In addition to a description of the preparation and properties of the films, it is shown that the morphology…
Results of a detailed investigation of the structure and electron-transport properties of ${\mathrm{La}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathit{A}}_{\mathit{x}}$${\mathrm{MnO}}_{3}$ (A=Ca, Sr) over a wide range of compositions are presented along with those of parent ${\mathrm{LaMnO}}_{3}$ containing different…
A suitable relationship between the linear refractive index n0, the energy gap Eg, and the nonlinear refractive index n2 has been looked for on the basis of experimental and theoretical data reported in the literature for numerous simple oxides. It has been established that the nonlinear refractive index increases wit…