Materials Literature
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Photoelectric yields and directional photoemission spectra for clean (100) and (111) faces of copper measured with provision for varying the angle of incidence and the light polarization, and with photon energies up to 6.60 eV, are presented. Contrasting the structureless Fowler-like behavior of the (100) face, the (1…
Abstract A detailed study of the shrinkage behaviour of homopolymers and copolymers of acrylonitrile has been made. Apart from chemical shrinkage, a physical shrinkage, which is independent of temperature and oxidizing gas was observed. This shrinkage occurs even at temperatures below 180°C. The effect of temperature…
New optically active biphenyl compounds have been synthesised. Low-melting mixtures with biphenyl nematogens give stable, room-temperature cholesteric liquid crystals of positive dielectric anisotropy. These give the cholesteric-nematic electro-optical phase-change effect. Mixtures of the new compounds exhibit thermoc…
We have studied the behavior of several nematics in Couette flow with homeotropic boundary conditions. When Leslie's viscosity ${\ensuremath{\alpha}}_{3}>0$, the director tumbles at a critical shear rate, ${S}_{c}$. When $S>{S}_{c}$ a stable, stationary state is observed. When $S>{S}_{E}>{S}_{c}$, the flow…
A model is discussed which for the first time provides a unified description of many electrical and optical properties of chalcogenide glasses. It is proposed that localized gap states are at dangling bonds, and that lattice-distortion effects are sufficiently strong that these states exhibit an effective negative ele…
Comparing recent experimental results of the thermal and acoustic properties of glasses, it appears that the degree of purity and the method of sample preparation have a noticeable influence on the specific heat, but hardly any effect on the phonon transport properties such as the thermal conductivity, ultrasonic atte…
A model and an approximate theory is presented for conduction in solids which have a charge-ordered low-temperature phase and show a first-order phase transition of 'semiconductor-semimetal' type at a characteristic temperature T nu (e.g. Fe 3 O 4 ). The structure and the conduction mechanisms of the low-temperature p…
Measurements of the thermal conductivity of type I diamonds have been analysed in terms of various phonon-scattering processes. From the relations between the point-defect scattering rates and the total nitrogen contents, it appears that the nitrogen occurs in groups of approximately 10 atoms. The relation between nit…
Enol derivatives in the chlorophyll series. 13 2 ‐Desmethoxycarbonyl‐17 3 ‐desoxy‐13 2 ,17 3 ‐cyclochlorophyllide a‐enol and a method for the introduction of magnesium into porphinoid ligands under mild conditions Magnesium transfer from the iodo‐magnesium salt of 3,5‐di‐ t ‐butyl‐4‐hydroxy‐toluene (BHT) into methyl p…
Enol derivatives in the chlorophyll series. Preparation of 13 2 ,17 3 ‐cyclopheophorbide enols 13 2 ,17 3 ‐Cyclopheophorbide enols have been prepared as model systems for studying the effect of ring E enolization upon the properties of chlorophyll derivatives.
The structure of the variable portions of a K-type Bence-Jones protein REI forming a dimer has been determined by X-ray diffraction to a resolution of 2.0 A. The structure has been refined using a constrained crystallographic refinement procedure. The final R value is 0.24 for 15000 significantly measured reflections;…
The doublet at 850 and 830 cm-1 in the Raman spectra of proteins containing tyrosyl residues has been examined as to its origin and the relation of its components to the environment of the phenyl ring, the state of the phenolic hydroxyl group, and the conformation of the amino acid backbone. Raman spectral studies on…
Article Determination of the crystal symmetry of the polymorphs of thallium indium disulfide, TlInS2 was published on November 1, 1975 in the journal Zeitschrift für Kristallographie - Crystalline Materials (volume 141, issue 1-6).
Abstract The DTA patterns of synthesized coprecipitated gels, the SiO2–Al2O3–Sc2O3–H2O system, resembled that of allophane as well as those of coprecipitated gels, the SiO2–Al2O3–M2O3–H2O system (M: Fe, Ga, or In). The exothermic reaction around 980 °C in the DTA was confirmed to arise from the formation of mullite. T…
According to earlier measurements with the two-aperture method, the brightness of electron guns has sometimes a maximum value near the cut-off potential. This result has been confirmed by means of the lens method. Experiments with well-oriented monocrystalline spherical cathodes lead to the result that a brightness ma…
The effects of the background vacuum level and of atomic migration on the stability of pulsed-field emission have been investigated. Initial studies concerned the emission characteristics that depend on the emitter temperature. Then the effects of the bias field and the change of the emitter shape were considered, in…
Microminiaturization for the production of modern large-scale integrated circuits requires electron-optical devices capable of recording more than 10 000 resolved lines per frame at a resolution of 0.1 μm. Magnetic demagnifying electron-projection systems with compensated chromatic field aberrations are capable of rec…
Abstract The accelerated aging of a vulcanizate of fluorosilicone rubber was studied by four methods: infrared spectroscopy, GPC, weight loss, and stress relaxation, with the object of gathering information pertinent to understanding the basic mechanism of its aging. No changes were observed in infrared spectra of the…
Specific rates have been measured for hydrogen–water deuterium isotope exchange over unsupported nickel promoted with about 20% of various metal oxides. The oxides used were Cr 2 O 3 , MoO 2 , MnO, WO 2 −WO 3 , and UO 2 . Nickel surface areas, which are required to measure the specific rates, were determined by hydrog…
Abstract The effects of diffusion in the oxidation of cis ‐1,4‐polyisoprene vulcanizates were investigated by means of the stress relaxation method. It was assumed that the diffusion of oxygen is coupled with first‐order oxygen consumption and that the rate of chain scission is proportional to the rate of oxygen consu…