Materials Literature
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Synthesis of La/sub 1-x/Sr/sub x/MnO/sub 3/ (x=0.1, 0.2 and 0.3) by homogenous coprecipitation method using urea as precipitant agent is reported. The particles are smaller than 200 nm after heating at 950/spl deg/C. Temperature dependence of the electrical resistivity was found to be similar to the reported value for…
A recently developed Rigaku parallel-beam X-ray diffraction system equipped with a parabolic graded-multilayer mirror in the incident beam and a parallel-slits analyzer in the diffracted beam was used for precision high-temperature diffraction studies. The lattice parameters a and c of α-Al 2 O 3 at room temperature a…
Four new species of Pleurosigma are described from the region of Alexandria in Egypt: P. williamsiisp. nov., P. mariutensissp. nov., P. ramlehensissp. nov. and P. rushdyensissp. nov. The taxa had been previously misidentified as P. rigidum W. Sm., P. elongatum W. Sm., P. speciosum var. sumatricum H. Perag. and P. form…
Abstract [2.2]Paracyclo(3,6)carbazolophane (1a) and [2.2](1,4)naphthaleno(3,6)carbazolophane (1b) were prepared. The structures of 1a and 1b were characterized by 1H NMR. X-ray analysis of 1a revealed that the carbazole ring extremely deviates from the conjugated plane. Electronic spectra of 1a and 1b showed the broad…
This paper reports on the results of crystal chemical analysis and computer simulation of the defect structure of potassium dihydrogen phosphate (KDP) containing impurities of bivalent and trivalent metals. It is shown that these impurities can form defect centers of different types: isolated centers formed by M 3+ an…
Heavily boron-doped nanocrystalline (nc) diamond films were deposited using microwave plasma chemical vapor deposition process in which the growing film surface was continuously bombarded by H+ and hydrocarbon ions. The dependency of grain size and phase purity on the process parameters and boron incorporation was inv…
Abstract The conditions of heat and moisture transport in a car-seat upholstery package are briefly presented, and the necessity of investigation especially of moisture transport is stressed. Three upholstery packages of different furniture covering textiles have been tested with the use of a measuring system for asse…
Abstract Modern disposable articles for personal and health care should offer excellent absorbency as well as comfort in use, need to be aesthetic and ensure discretion. There are numerous challenges facing the designers of nonwoven fabrics for absorption of body fluids, which result from various engineering contradic…
We studied the optical performance of a reflective wire-grid polarizer designed for visible light. The polarizer reflects E polarization and transmits H polarization with low losses. The studies of transmission and reflectivity of nonpolarized and polarized light from single grids and stacked grids show that the optic…
Magnetization and remagnetization processes in a close-packed nanodispersed barium hexaferrite powder sample in the magnetically stable state were analyzed. Reversibility effects were discussed in terms of interparticle interaction. Judging from the magnetization curve and the parameters characterizing remagnetization…
A full analysis of magnetization reversal of a uniformly magnetized body by coherent rotation is presented. The magnetic energy of the body in the presence of an applied field H is modeled as E=(/spl mu//sub 0//2)M/sup T/ DM-/spl mu//sub 0/H/sup T/M, where T denotes a matrix transpose. This model includes shape anisot…
The conventional analytical description of axial shielding for cylindrical shields is based on the assumption that the field reduction inside the shield is due to the demagnetizing field within the equivalent ellipsoid. It seems more reasonable, however, to employ in the axial shielding equation the demagnetizing fact…
A new compound, [Cu(dpyam)(OH)]2(ClO4)2 (dpyam = di-2-pyridylamine) is studied in detail and characterised by magnetic susceptibility and heat capacity measurements. This unique compound exhibits two phase transitions at 192 and 116 K. To obtain more insight into the origin of this transition, X-ray crystal structures…
The changes of supramolecular structure of PET fibres upon supercritical fluid (SCF) dyeing, conventional water dyeing, hot air thermofixation at 130 °C, respectively were studied. The following observations were made; the increase in crystallinity is nearly alike with the SCF and water treated sample, while hot air r…
Polymer cholesteric liquid-crystal flakes suspended in a fluid with nonnegligible conductivity can exhibit motion in the presence of an ac electric field. The plateletlike particles with a Grandjean texture initially lie parallel to the cell substrates and exhibit a strong selective reflection that is diminished or ex…
Abstract Compounding ground tire rubber (GRT) with commercial polyolefins such as polypropylene (PP) is a possible way of recycling GRT. These new blends can provide low cost materials. The present study describes new materials which are obtained by the ultrasonically treated PP/GRT blends. In order to improve the eff…
We report on our observation of the formation of permanent holographic gratings induced in nematic liquid crystals doped with carbon nanotubes by the simultaneous action of both a spatially modulated light and dc electric field. Properties of these irreversible gratings were investigated with a normally incident laser…
Abstract Three raw samples of Fe-rich smectites from Gafsa (Jebels Shemsi and Hammadi, Tunisia) have been characterized by different techniques which indicate that they contain (15 – 20%) illite, probably interstratified and to a lesser extent they also contain kaolinite, calcite, quartz and Fe oxides. These samples p…
For the first time, time-resolved emission and excitation spectra, as well as decay kinetics of luminescence of CsCl : Tl single crystals have been measured at 10 K under excitation in the 4–20 eV energy range. The results obtained confirm the earlier conclusion that the emission spectrum of the main thallium centres…
It is shown that high-temperature treatment of self-poled lead zirconate-titanate films containing an excess of lead oxide, followed by prolonged storage at room temperature, results in a charge redistribution in the near-electrode regions of ferroelectric films. Such heat treatment destroys, as a rule, the self-poled…