Materials Literature
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The crystal structure of the mesoionic compound 2-oxo-3-benzoyloxazolo[3,2-a]pyridine (C 14 NO 3 H 9 ) has been determined from X-ray powder data using the grid search procedure. The crystal symmetry is orthorhombic (space group Pna2 1 , a=7,940(1) Å, b=24,562(3) Å, c=5,402(1) Å). The results of Rietveld refinement (R…
The present study describes the fabrication and characterization of cluster diamond (CD) dispersed Cu composites. A powder metallurgy method combining mechanical milling and hot pressing was used to produce CD dispersed Cu composites. The Cu matrix powders and CD were mechanically milled at 500 rpm in an Ar atmosphere…
In this paper we report on the synthesis and characterization of new mixtures of achiral liquid crystalline side-chain polymers with their monomers. The samples have a basic structure similar to materials prepared earlier showing antiferroelectric behaviour. They are investigated to study the influence of peculiar dif…
Polycrystalline Al 2 O 3 ceramics doped with Cr (sintered ruby) up to high concentrations (0.66, 0.76 and 0.97 wt%) were fabricated with an extrusion molding process using Al 2 O 3 and Cr 2 O 3 powders. It was found from absorption spectra that a high concentration of Cr ions was optically activated. The fluorescence…
We show that the Barkhausen avalanches exhibit power law distributions and scaling exponents belonging to two distinct universality classes. We explain these results in terms of the critical behavior of the domain wall at the depinning transition, with exponents set by the long-range dipolar interactions arising from…
This paper investigates inter-bubble gas diffusion in two-dimensional (2D) and three-dimensional (3D) wet foams using the bubble dynamics model. The bubble dynamics model avoids the need to consider T1 type bubble rearrangement events in three dimensions explicitly. Foam bubbles are approximated as overlapping paralle…
The internal friction Q–1 and the square of vibration frequency f2 (proportional to shear modulus G) were measured as functions of temperature on undoped Pb(Zr0.7Ti0.3)O3 (PZT73) and Pb(Zr0.3Ti0.7)O3 (PZT37) ceramics from 20 to 500 °C. Experiments were performed on an inverted torsion pendulum at low frequencies (0.1…
Simultaneous dielectric permittivity measurements and analysis of the first and the second harmonic electro-optical responses have been performed on a 26 mum thick planar oriented sample of the antiferroelectric liquid crystal tolane C8, which has a polymorphism similar to that of MHPOBC. Comparison of these measureme…
In this study, we investigated the reactivity of chromium, iron, and surface-treated 304L stainless steels (SS) toward molecules representing model epoxy resins. These molecules were ammonia (a basic probe molecule also representative of the hardener amine group), 1,2-epoxybutane (for epoxy groups) and 2(methylamino)e…
Abstract The effect of SO2 on activity for NO reduction by methanol over Ag/Al2O3 in the presence of excess oxygen has been investigated. Selective catalytic reduction activity was not decreased but increased and most effective NO reduction temperature shifted from 200-250 °C to 300-350 °C by pre-sulfated Ag/Al2O3 or…
X-ray Photoelectron spectroscopy (XPS) was used to detect major changes to the surface chemistry of polypropylene (PP), high density polyethylene (HDPE) and styrene-butadiene block copolymer (SBS) caused by electrochemical treatment using dilute nitric acid as electrolyte. Large increases in adhesion levels were obser…
We studied by lattice simulation the surface diffusion and relaxation of isolated, self-avoiding polymers partially adsorbed onto a flat surface. The key parameters describing the system are the number of segments in the chain, N, the adsorption energy of a segment, expressed as a dimensionless surface temperature Ts,…
The long-term comfort and durability properties of the flexible molded foams used in many forms of transportation seating are a subject of increasing interest to foam molders and seat producers. Existing and proposed new specifications for load bearing and other fatigue losses have necessitated a new look at the funda…
D.C. conductivity of the ferroelectric BaHPO4 is measured and is found to lie between usual conductivities of semiconductor and insulator. Its temperature dependence shows intrinsic conduction in defective crystals due to H+ ions. The a.c. conductivity calculated from the measured dielectric constant follows σ˜ω1.54,…
Based upon net collections of various mesh sizes (20–235 μm) from the open ocean, small (mostly 6–31 μm), abundant, bicapitate Nitzschia species have been found to aggregate on substrates. As many investigators have noted from water samples, they are also present as single cells in the plankton, thus filling two diffe…
Abstract Practical countermeasures to prevent the occurrence of ferroresonance in floating systems are compared. Most attention is paid to the design of practical damping circuits. Existing criteria to determine the necessary ohmic load are evaluated and a new mathematical tool based on harmonic balance is presented.…
Abstract By IR observation, Lewis acid sites of medium strength were found by CO adsorption on a mesoporous Ta-TMS-1 while no basic sites were detected by CO2 adsorption. Methyl migration of methoxy species and formation of methoxy species from adsorbed dimethyl ether were quantitatively demonstrated.
The magnetic and electrical properties of R1−xSrxCoO3 materials (R=La, Pr, Nd, Gd) (0⩽x⩽0.50) are studied. Rare-earths with angular momentum L≠0 enhance coercive field values. They are maximum for R=Nd (the highest L) and much smaller for Gd and La (L=0). The result is interpreted as the contribution of the L–S coupli…
The relaxation of the initial permeability has been measured in polycrystalline Ti-doped Ba–W hexaferrites with nominal composition BaTixFe18−xO27, with x ranging among x=0 and 0.3. The samples have been sintered at different temperatures in the 1250 °C<T<1350 °C range in a reducing CO2 atmosphere and ra…
Abstract Two types of periodic surfaces were fabricated by utilizing two-dimensionally ordered arrays, in one case as a template and in another as a mask. In the first case, a bulb-like microstructured surface was formed, and, in the second, a cylinder-like microstructure. The Raman spectra of these films indicate tha…