Eliminierungsreaktionen in der Pyrrol‐Reihe
Abstract Heiße Phosphorsäure eliminiert Carboxyl, Äthoxycarbonyl‐ und Acyl‐Gruppen aus Pyrrol· Derivaten.
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Epitaxial Synthesis of Diamond in the Metastable Region
Recent trends in the preparation of synthetic diamonds, relying on the influence of surface forces exerted by the diamond seed crystal on the carbon deposition processes, are discussed. Epitaxial synthesis can occur from carbon-containing gases or from molten metals. Foreign publications and patents are discussed as w…
The density and distribution of dislocation etch pits in deformed cadmium crystals
Cadmium single crystals of high purity have been deformed at room temperature, by basal slip in uniaxial tension, at a strain rate of 8 × 10−6 s−1. The density and distribution of edge dislocations have been examined by an etch pit technique and it is found, in contradiction to the results of a similar study by Kratoc…
DIRECT OBSERVATION OF SINGLE-DOMAIN SrTiO3
A single-domain SrTiO3 crystal is obtained by stressing along the [110] direction at 2°K and is observed optically for the first time. Domain structure under [001] stress is also examined. The importance of understanding the domain structure is discussed.
Collagen structure in solution. IV. Conformational properties of refolded cross-linked chains
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCollagen structure in solution. IV. Conformational properties of refolded cross-linked chainsPeter V. Hauschka and William F. HarringtonCite this: Biochemistry 1970, 9, 19, 3745–3754Publication Date (Print):September 15, 1970Publication History Published online1 May 2002Publ…
93Nb NMR Study of the LiNbO3–LiTaO3 Solid-Solution System
The 93Nb nuclear magnetic resonance has been studied in sintered powders of the solid-solution system LiNbO3–LiTaO3. The Nb nuclear quadrupole coupling constant decreases linearly with an increase in LiTaO3 concentration and this behavior agrees with the calculated electric field gradient. A variation of the 93Nb NMR…
Diffusion and Correlation Effects in Copper-Zinc Alloys
The self-diffusion coefficients of copper in copper-zinc alloys containing 0-4-at.% zinc have been measured at 894.4 and 946.7\ifmmode^\circ\else\textdegree\fi{}C. These results, together with the correlation factor for the diffusion of zinc in copper as determined from measurements of the isotope effect, are used to…
Photoabsorption near theLII,IIIEdge of Silicon and Aluminum
The absorption coefficients of Al, Si, and SiO were determined in the extreme uv with high spectral resolution, using synchrotron radiation. A detailed comparison of the ${L}_{\mathrm{I}\mathrm{I},\mathrm{I}\mathrm{I}\mathrm{I}}$ edge in the metal and in the semiconductor shows important differences. The spikes observ…
Spin-Disorder Scattering in Iron- and Nickel-Base Alloys
The electrical resistivities of iron-base alloys with Cr, W, Mn, Ru, Co, Ni, Si, or Ge solutes, and of nickel-base alloys with Cr, Fe, Cu, or Pd solutes were measured from 4.2 \ifmmode^\circ\else\textdegree\fi{}K to above the Curie temperatures $\ensuremath{\theta}$. The solute resistivities ${\ensuremath{\rho}}_{r}(T…
Debye-Waller Factors and the PbTe Band-Gap Temperature Dependence
Measurements of the temperature variation of x-ray diffraction peak intensities have been used to show that the mean-square thermal displacement of Pb in PbTe is approximately twice that of Te. This phenomenon is explained, using a calculation of the mean-square displacements from vibrational eigenvalues and eigenvect…
New Set of Tetrahedral Covalent Radii
A table of additive covalent radii for tetrahedrally coordinated crystals is obtained by simple quantum-mechanical considerations using the bond lengths of the four diamond-type crystals and only two free parameters. The 39 bond lengths so obtained agree with experiment with an rms error of less than 1%. The extension…
Calculation of the Band Structure and Optical Constants of Diamond Using the Nonlocal-Pseudopotential Method
The electronic band structure and optical constants of diamond are calculated using the empirical-pseudopotential method with an additional $\ensuremath{\ell}=1$ nonlocal term ${V}_{\mathrm{NL}}(\stackrel{\ensuremath{\rightarrow}}{r})$ added to account for the strong potential experienced by $p$ electrons in the core…
Viscous Liquids and the Glass Transition. II. Secondary Relaxations in Glasses of Rigid Molecules
The dielectric loss factor and dielectric permittivity of 8–16 mol% solutions of chlorobenzene, o-dichlorobenzene, and 1-chloronaphthalene in cis-decalin; 50–60 mol% mixtures of pyridine with chlorobenzene, bromobenzene, 1-chloronaphthalene, and toluene; 50–60 mol% mixtures of tetrahydrofuran with bromobenzene and 1-c…
Order Parameter and Phase Transitions of Stressed SrTiO3
EPR spectra of $\mathrm{F}\mathrm{e}\ensuremath{-}{V}_{\mathrm{O}}$ pairs were used to study how the order parameter of SrTi${\mathrm{O}}_{3}$ varies with uniaxial stress applied to a (111) face. A second-order cubic-trigonal phase boundary appears above the stress-free transition temperature ${T}_{a}$. A first-order…
Temperature-Dependent Tilt Angle in the SmecticCPhase of a Liquid Crystal
Measurement of the tilt angle of the smectic $C$ phase of terephthal-bis-($4\ensuremath{-}n\ensuremath{-}\mathrm{b}\mathrm{u}\mathrm{t}\mathrm{y}\mathrm{l}\mathrm{a}\mathrm{n}\mathrm{i}\mathrm{l}\mathrm{i}\mathrm{n}\mathrm{e}$) has been made using conoscopic observation and circularly polarized light. The new phenomen…
Optical and Magnetic Investigations of the Localized States in Semiconducting Glasses
We measured optical absorption and magnetic susceptibility of amorphous ${\mathrm{As}}_{2}$${\mathrm{S}}_{3}$ as a function of temperature. An exponential variation of absorption constant with photon energy was found in the range $0.09<\ensuremath{\alpha}<0.5$ ${\mathrm{cm}}^{\ensuremath{-}1}$. A Curie term in t…
Field-enhanced conductivity effects in thin chalcogenide-glass switches
The anomalous behaviour of chalcogenide-glass switches, in the thin-film limit, is incorporated into the electrothermal switching model by taking account of both temperature and field dependences of the electrical conductivity. Calculations of the critical field as a function of temperature and thickness are compared…
Thermal degradation of copolymers of styrene and acrylonitrile. III. Chain‐scission reaction
Abstract The chain‐scission reaction which occurs in copolymers of styrene and acrylonitrile has been studied at temperatures of 262, 252, and 240°C. Under these conditions volatilization is negligible, and chain scission can be studied in virtual isolation. At 262°C three kinds of chain scission are discernible, name…
The crystallite size of pyrolytic graphite
x-ray line broadening techniques have been used to determine both a - and c -direction crystallite sizes for a range of pyrolytic graphite samples whose effective formation temperature lay between 2330 and 3020°C. x-ray line profiles were analysed using the variance method. It is shown that if the proper allowance is…
EVIDENCE OF DICALCIUM PHOSPHATE PRECIPITATION IN A CALCAREOUS SOIL
Summary The‘precipitated‐calcium/precipitated‐phosphorus’ mole ratio approached a limiting value of 1 as the amount of phosphate, added to a suspension of calcareous soil in 0·01m CaC1 2 , was increased, indicating the precipitation of dicalcium phosphate. The phosphate and lime potentials provided further evidence th…