Materials Literature
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A model calculation based on the effective-medium theory of the oxygen-induced reconstruction of the (110) and (100) surfaces of Cu is presented. Equilibrium structures are calculated from a minimization of the total energy of the system. Missing-row-type reconstructions are found to be most stable in both cases, and…
Abstract This paper reports the use of Electron Parametric Resonance (EPR) for preliminary investigation of radicals formed from P,p'‐dioctyldiphenylamine (‘Irganox’, an antioxidant) during heating in a synthetic aviation lubricant base oil di‐2‐ethylhexylsebacate. Relative concentrations of radicals were found to be…
Abstract After a and ß irradiation of fine-grain samples from quartz annealed at 650 oC three PTTL peaks appear at 100 oC, 150 oC and 195 oC after first readout up to 245 oC and UV illumination. Two different wavelengths, 315 nm and 275 nm cause the most significant PTTL. The peak heights of the PTTL peaks depend on i…
The kinetics of the solid-state reaction between Al and Pd is studied in the geometry of a lateral Al-Pd diffusion couple in the temperature range between 250 and 430 °C. The first reaction phase is the crystalline Al3Pd2(δ) phase. After the growth of Al3Pd2 reaches a critical length, the quasicrystalline decagonal Al…
Abstract The band texture formation of nematic poly(1,4‐phenyleneterephthalamide) (PPTA)/H 2 SO 4 solutions after shearing between rotating plates was studied. For a thickness of the solution layer larger than 20 μm the band texture appears immediately after the cessation of shearing, but a critical shear rate is need…
A series of TiO(2) flint glasses has been developed for producing GRIN glass by ion exchange. Both positive and negative axial and radial gradients were fabricated in high index glasses by exchange of Li(+) for Na(+) and Na(+) for Li(+), respectively. Index changes to 0.05 and depths up to 6 mm were achieved and a wid…
SUMMARY. An ecological study of two small maritime Antarctic lakes on Signy Island, South Orkney Islands, was undertaken from January 1986 to March 1987. Analysis of diatom counts from the lakes provided examples of oligotrophic and mesotrophic ecosystems. A diverse community of 104 epiphytic taxa was identified. Twen…
Abstract The figure of merit Z is a measure for the effectiveness of the thermoelectric material p‐(Bi 1− x Sb x ) 2 Te 3 and depends on the valence band structure, the charge carrier scattering, the lattice thermal conductivity, and the free carrier density. It is shown that crystals with the composition x = 0.75 are…
Latex stage epoxidation of natural rubber with in-situ formed performic acid with and without acetic acid at room temperature were studied at various feed composition. Epoxidised natural rubber was characterised by IR, NMR and DSC. A simple kinetic model was developed from laboratory ex perimental data. Various side r…
Abstract We present data on the mechanisms of phototransferred thermoluminescence (PTTL) and optically stimulated luminescence (OSL) in single crystal CaF2:Mn (3%) and in TLD-400 chips. The TL peak under study is the main dosimetry peak near 275 oC. From measurements of the excitation spectra for PTTL it is found that…
Abstract This paper presents an experimentally‐based analysis of the continuous filament regime of the melt‐blowing process. The experiments were performed with a versatile air‐polymer die, several die operating temperatures, and three different polymer feed resins. The measurements discern the effects upon the final…
Abstract Thermal expansivities along the a, b, and c axes of the orthorhombic unit cell of poly (ether‐ether‐ketone (PEEK) crystals have been determined from 160 to 470 K by wide‐angle x‐ray diffraction. The expansivities along the a and b axes are positive while the expansivity along the c (chain) direction is negati…
We report the design and performance of narrowband transmission filters employing the rapidly changing extinction coefficient that is characteristic of BaF(2) and SiO(2) films within certain wavelength intervals in the vacuum ultraviolet. We demonstrate the design concept for two filters centered at 135 nm for BaF(2)…
Abstract 2,5-Bis(dicyanomethylene)-2,5-dihydrofuran with a 2,5-furanoquinonoid skeleton and its extensive conjugated homologues, 5,5′-bis(dicyanomethylene)-5,5′-dihydro-Δ2,2′-bifuran (8a), and 5,5″-bis(dicyanomethylene)-5,5″-dihydro-Δ2,2′:5′,2″-terfuran (12a), have been prepared as a new type of oxygen-containing elec…
<div class="htmlview paragraph">Twenty-two physical and chemical properties of a typical automatic transmission fluid were determined. In most cases the properties were determined over a range of temperatures. In general, air solubility, volumetric thermal expansion, and specific heat increase with increasing te…
The effective thermal conductivity of binary dispersed composites prepared from mixed and compacted powders of AgCl and low-density polyethylene was measured over the entire range of volume fraction at temperatures in the range 100–330 K together with pressures up to 1.75 GPa. Measurements were made using the transien…
Abstract A simple method for the consolidation of all of the conventional cushion curves for a particular material into a single relationship is discussed. The method requires only one of the usual cushion curves for an arbitrary drop height and cushion thickness to deduce the dynamic stress‐strain curve for the mater…
Abstract The thermal annealing properties of (H3O4)0 centres in single crystal SiO2 were studies by means of electron spin resonance (ESR). The data indicate that these centres take part in the TL process at 110 oC in this material. The mechanism suggested for this TL signal is the thermal release of electrons from (G…
The possible use of Fourier transform infrared reflection‐absorption spectroscopy (FT‐IRAS) and Raman spectroscopy for surface studies of thin (<10 nm) corrosion products on Cu has been explored. Cu samples were exposed to 75% relative humidity and 25°C in flowing air, with additions of 0.25 ppm of SO 2 and NO 2 . X‐r…
Abstract The efficiency of α, I pair creation at exciton decay is high at 4.2 K for KCl, KBr, and RbBr crystals for which H centers are oriented along 〈110〉. The efficiency of α, I pair creation by VUV‐irradiation at 4.2 K is extremely low for NaCl crystals for which H centers are oriented along 〈111〉. The process of…