Materials Literature
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Abstract The backscattered electron signal (BSE) in the scanning electron microscope (SEM) has been used for investigation of a specimen surface composition (COMPO mode). Creation of a material composition map is difficult because the dependence of backscattering coefficient η on the atomic number Z for Z > 40 is n…
Abstract Parameters of wetting dry fibers with non‐Newtonian liquids are studied experimentally. Rheological tests show that seven of the 13 test liquids adhere to Newtonian behavior with a wide range of viscosities 3 < μ < 30,000 mPa·s. The other six liquids show shear‐thinning behavior with different flow indi…
Abstract The incorporation reaction of zinc(II) and cadmium(II) into 21-(4-nitrobenzyl)-5,10,15,20-tetrakis(4-sulfonatophenyl)-23H-porphyrin (NO2Bz(Htpps)4−; HP4−) and the dissociation reaction of the metalloporphyrins ([MP]3−) have been studied spectrophotometrically at I = 0.1 mol dm−3 (NaNO3). The formation rate of…
The effects of ambient pressure ranging from 101 up to 3040 kPa and temperature from 233 up to 353 K on burning rate of both high and low fuel content Si-Pb3O4 mixtures have been investigated. Also tests have been made to further reduce pressure effects using additions of metal fluorides. Sodium and calcium fluorides…
Magnesium oxide-supported polytitazane copper complex is prepared and found to be a very effective catalyst for the Baeyer-Villiger oxidation of ketones and cyclohexanol in the presence of an aldehyde as a reductant under an atmospheric pressure of oxygen at room temperature. The δ-valerolactone and δ-caprolactone can…
The dynamics of guanidinium nitrate studied by inelastic neutron scattering, infrared and Raman spectroscopy is reported. The experimental frequencies were assigned to the fundamental modes of nitrate and guanidinium ions on the basis of qualitative considerations. The assignment of the out-of-plane bending mode γ(N–H…
X-ray diffraction based on the comparison between the experimental and the calculated (20,11) and (02,31) powder profiles enabled determination of the structural characteristics of a Tunisian nacrite. The nacrite has space group Cc and the stacking mode is 2M. The two-layer periodicity could be described by a rotation…
The inherent properties of diamond make it an ideal material for detectors in the high rate, high radiation environments near the collision point of future colliders such as the LHC. We have constructed charged particle position sensitive detectors using high quality chemical vapor deposited (CVD) diamond. Using detec…
The liquidus isotherms for the Ga–As–Bi system were determined at 973 and 923 K in the Ga–As–GaAs region. The liquid phase epitaxial growth of GaAs from Ga–As and Ga–As–Bi solutions were investigated. The addition of ten atomic percent of Bi to the Ga–As solution increase the growth rate of the grown epilayers nearly…
Challenges in the integration of ferroelectric nonvolatile memories with complementary metal-oxide-semiconductor (CMOS) technology for low-voltage and low-power applications are discussed. The main driving force for commercialization is to take advantage of the true high-speed (100 ns), low-voltage (0.9 V) write poten…
Abstract A novel method for the preparation of water‐soluble polypyrrole graft copolymers with polyamines or polyimines is described. The polyreaction is performed in acidic solution by using chemical oxidants, e.g. iron(III) chloride or ammonium peroxodisulfate. The graft copolymers showed electrical semiconductivity…
What can be done with radioactive waste? This extremely difficult question has not really been answered anywhere in the world; yet it must be answered. Like death and taxes, radioactive waste is with us—it cannot be wished away. This special, five-article issue of PHYSICS TODAY reviews the technical problems and risks…
We found aromatic copolymers comprising 4′-hydroxy 4-biphenyl carboxylic acid and 6-hydroxy 2-naphthoic acid with high second-harmonic-generation (SHG) activity. The polarization dependence of SHG in the solid film formed from the nematic phase reveals uniaxial and biaxial polar orderings.
A new theoretical method of evaluating polarizabilities of liquid crystals is presented and applied to the liquid crystalline compounds, namely n-alkyl-p-(4-ethoxy benzylidene amino)--methyl cinnamates, which exhibit smectic A and nematic phases. In the present method, vibrational frequencies are used to evaluate forc…
A synthesis of the d,l and meso forms of isochrysohermidin 3 is outlined which employs the singlet oxygen oxidation of pyrroles as the key step. The bipyrrole precursor 8 was synthesized from a 3-hydroxy monopyrrole which, in turn, was prepared by addition of methylamine to a vinyl vicinal tricarbonyl.
An analysis of Li‐intercalation and deintercalation in a tungsten‐oxide based electrochromic device is presented. An hysteresis between intercalation and deintercalation has been separately observed in both the built‐in potential and the optical efficiency of the devices. This hysteresis is explained by a two‐phase mo…
Recently, the innovative metallocene based catalyst technology has offered a new class of olefin polymers with molecular structures different from the traditional polyolefins produced with Ziegler-Natta catalysts. Metallocene polyolefins exhibit improved clarity, flexibility and impact resistance in comparison with co…
Abstract The glass transition temperatures of impact modified PVC with different amounts of lubricants have been used to define two new parameters of lubrication: the saturation concentration and the efficiency constant. The use of lubricants at significantly lower concentration than the saturation concentration ensur…
The sol−gel method was employed to prepare the precursor of zirconium oxide by the reaction of zirconyl chloride octahydrate (ZrOCl 2 ·8H 2 O and EDTA in ammonia. The reaction of ZrOCl 2 · 8H 2 O and the ionized complexing agent R(COO - ) n was achieved through sequential hydrolysis (4ZrOCl 2 ·8H 2 O + 20H 2 O → [Zr 4…
Parts I and II explain and evaluate a theoretical model that can predict the stress-strain and torque-strain curves of a yarn. Part III discusses the results of the experimental work on input parameters, that is, properties and arrangement of the fibers in the yarn. When appropriate values are taken for fiber and yarn…