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Reinjection of powder in wet process rotary kilns
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Influence of setting retarders on concrete shrinkage
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Criteria on cement specifications
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Use of flying ashes according to the recent Pittsburgh symposium
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Einfluß der kristallstruktur und der überstruktur auf einige eigenschaften von polypropylen
Abstract Isotaktisches Polypropylen bildet bei der Kristallisation vier verschiedene Typen von Sphärolithen, die nach P ADDEN und K EITH als Typ I bis IV bezeichnet werden. Die Typen I und II zeigen eine monokline Kristallstruktur, während die Typen III und IV pseudohexagonal kristallisieren. Die Sphärolithe vom Typ I…
Mercury-photosensitized decomposition of dimethyl ether. Part II. The thermal decomposition of the methoxymethyl radical
The decomposition of the methoxymethyl radical, generated in the mercury-photosensitized decomposition of dimethyl ether, has been investigated over the temperature range 200 to 300 °C and the pressure range 3 to 600 mm Hg. The radical decomposes to give a formaldehyde molecule and a methyl radical. The effects of pre…
RELATIONSHIPS BETWEEN THE NONLINEAR ELASTIC CONSTANTS OF MONOCRYSTALLINE AND POLYCRYSTALLINE SOLIDS OF CUBIC SYMMETRY
The relationships between the third-order elastic constants of monocrystalline and polycrystalline (quasi-isotropic, randomly oriented) solids of cubic symmetry are derived according to elastic strain energy balances assuming negligibly small elastic strain energy contribution from mismatching of the grain boundaries.…
Dielectric Relaxations in Reduced Rutile (TiO2−x) at Low Temperatures
The complex dielectric constant of reduced rutile, $\mathrm{Ti}{\mathrm{O}}_{2\ensuremath{-}x}$, has been measured at frequencies between ${10}^{2}$ and ${10}^{5}$ Hz at temperatures between 1.2 and 50\ifmmode^\circ\else\textdegree\fi{}K. Three distinct relaxation processes have been observed: process I at temperature…
Isotope Effect in Self-Diffusion in Zinc
The isotope effect has been measured for self-diffusion in single crystals of zinc parallel and perpendicular to the $c$ axis at seven temperatures in the range 289-418\ifmmode^\circ\else\textdegree\fi{}C. A vacancy mechanism is found, with $\ensuremath{\Delta}K=0.93$, independent of temperature within the experimenta…
Internal Strain and Raman-Active Vibrations in Solids
In lattices in which not all ions possess inversion symmetry, internal-strain effects give rise to piezoelectricity and contribute to the elastic response. It is possible to describe these internal strains as static optical-phonon-mode displacements and to analyze the internal-strain contributions to the elastic and p…
Crystal Structure of Piezoelectric Bismuth Germanium Oxide Bi12GeO20
Piezoelectric Bi12GeO20 crystallizes in the cubic system with space group I23 and lattice constant a = 10.1455±0.0008 Å at 298°K. The complete x-ray scattering pattern within a reciprocal lattice hemisphere of radius (sinθ)/λ = 1.02 Å−1 was determined with PEXRAD. A total of 4812 reflections were measured, resulting i…
Thermal Expansions from 2 to 40°K of Ge, Si, and Four III-V Compounds
Linear thermal-expansion data are given for Ge, Si, GaAs, GaSb, InAs, and InSb at temperatures from 1.89\ifmmode^\circ\else\textdegree\fi{}K to approximately 40\ifmmode^\circ\else\textdegree\fi{}K. The data were obtained using a variable transformer as a sensor and are absolute in sample length changes. At the lowest…
Mobility of Charge Carriers in Semiconducting Layer Structures
The electrical resistivities and the Hall constants of the compound semiconductors GaSe, Mo${\mathrm{S}}_{2}$, Mo${\mathrm{Se}}_{2}$, and W${\mathrm{Se}}_{2}$, which crystallize in layer structures, have been measured at temperatures ranging from 100 to 700\ifmmode^\circ\else\textdegree\fi{}K. The Hall mobilities deri…
Aragonite in fossils
Abstract The distribution of aragonite in the skeletal parts of living organisms is reviewed, and its distribution in fossils is described on the basis of several hundred new determinations. Aragonitic fossils are extensively preserved in Tertiary sediments, and are common in Mesozoic rocks, particularly where the enc…
Electric Field Dependence of Optical-Phonon Frequencies
In electric-field-induced Raman-scattering experiments on the cubic perovskite SrTi${\mathrm{O}}_{3}$, a striking electric field shift and splitting of the "soft" optical phonon mode is observed. Experiments were done at temperatures ranging from 8 to 250\ifmmode^\circ\else\textdegree\fi{}K and for electric fields bet…
Fano Factor in Germanium at 77°K
The Fano factor in germanium at liquid-nitrogen temperature has been found to be $F=0.129\ifmmode\pm\else\textpm\fi{}0.003$ using $\ensuremath{\gamma}$ rays at energies from 0.122 to 4.8 MeV. $F$ appears to be independent of the primary energy in the investigated energy range. Care has been exercised to eliminate the…
Infrared Luminescence ofFe2+in ZnS
The infrared luminescence spectra of four different crystals of cubic ${\mathrm{Zn}}_{1\ensuremath{-}x}{\mathrm{Fe}}_{x}\mathrm{S}$ with ${10}^{\ensuremath{-}4}\ensuremath{\le}X\ensuremath{\le}{10}^{\ensuremath{-}2}$ have been measured at 5 and 77\ifmmode^\circ\else\textdegree\fi{}K. There is no appreciable luminescen…
Magnetic Interactions and Spiral Ground States in Spinels, with Application to ZnCr2Se4
It is found that five distinct distant-neighbor interactions must be considered in order to characterize adequately the Heisenberg energy in normal cubic spinels having diamagnetic $A$-site ions. The classical theory of the ground spin state is presented in terms of these interactions, which span a five-dimensional pa…
Semiconducting Properties of Ferromagnetic CdCr2Se4
Measurements of the electrical conductivity, the Seebeck effect, and the Hall effect were performed on hot-pressed Cd${\mathrm{Cr}}_{2}$${\mathrm{Se}}_{4}$ between 77 and 300\ifmmode^\circ\else\textdegree\fi{}K. The conductivity of $n$-type Cd${\mathrm{Cr}}_{2}$${\mathrm{Se}}_{4}$ (In-doped) shows a sharp minimum at 1…