Materials Literature
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In the variable pressure scanning electron microscope (VP-SEM) the incident electrons pass through a gaseous environment and the beam is scattered by these interactions. We show here that the experimental intensity profile of the scattered beam can be described as Gaussian in form to a high level of accuracy. This pro…
Le présent travail concerne la détermination des propriétés mécaniques des âmes nids d'abeilles de forme hexagonale et de leurs versions sur-expansées rectangulaires. Ces âmes en papiers Nomex® sont présentes sur les voiliers multicoques de courses océaniques entièrement réalisés à partir de sandwichs à peaux de tissu…
The microspinning technology has generally been used for cotton in the case of small scale spinning test methods (50 gram fibres). One type of silk fibre waste -pierced cocoonprepared previously as short silk fibre with cut length of 35 mm is blended with cotton fibre to obtain further data concerning two blending tec…
The electronic structure and plastic properties are investigated for a number of alkali halide crystals (CsCl, CsBr, CsI). First-principles calculations are carried out within the Hartree-Fock and density-functional theory approximations using several variants of the exchange-correlation functional, including the hybr…
Based on typification in Ehrenberg's original material, the nomenclature and taxonomy of Gyrosigma fasciola (Ehrenberg) J.W. Griffith et Henfrey are discussed. This diatom is compared to two morphologically similar taxa, Gyrosigma sulcatum (Grunow in Cleve & Grunow) Frenguelli and Gyrosigma arcuatum (Donkin) Sterrenbu…
Three‐dimensional silica fiber reinforced silicon nitride‐based composites were fabricated at 873–1073 K in ammonia using polyhydriomethylsilazane and perhydropolysislazane, respectively. The composites showed high weight pickups during repeated pyrolysis cycles, non‐brittle failure behavior with fiber pull‐out in the…
Results of neutron diffraction studies of R 0.5 Sr 0.5 MnO 3 manganites (R = Sm, Nd 0.772 Tb 0.228 , and Nd 0.544 Tb 0.456 ) performed to reveal the microscopic origins of the giant oxygen isotope effect recently discovered in Sm 0.5 Sr 0.5 MnO 3 are presented. It is shown that two crystalline phases differing in the…
Abstract Interfacial reaction between Cu and Ti 2 SnC during the processing of Cu–Ti 2 SnC composite was investigated by using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. It is shown that the reaction is closely related to the reaction temperature, reaction time, and relative…
Este trabalho trata do efeito da hibridização do reforço, através da adição de uma carga mineral (bentonita) nanoparticulada, no desempenho mecânico de compósitos poliuretano/sisal contendo 25% em massa de fibras de sisal e moldados por compressão. As propriedades mecânicas, de tração e impacto, dos sistemas compósito…
The high-temperature characteristics of donor-doped SrTiO 3 /indium tin oxide (ITO) Schottky solar cells were investigated by current–voltage and impedance analyses at various oxygen partial pressures ( P O 2 ) (1–10 -4 bar) at 873 K. Both current–voltage and impedance characteristics showed a reversible oxygen partia…
The ferrimagnetic compounds Ca(Cu x Mn 3− x )Mn 4 O 12 of the double distorted perovskites AC 3 B 4 O 12 family exhibit a rapid increase of the ferromagnetic component in magnetization at partial substitution of square coordinated (Mn 3+ ) C for (Cu 2+ ) C . In the transport properties, this is seen as a change of the…
The grain microstructure evolution in the course of two dimensional (2D) grain growth is considered in greater detail, taking into account the influence of grain boundary triple junctions. It is shown that there are two limiting regimes of grain growth in polycrystals: the first one is associated with the situation wh…
The photoelectric properties of TlGa 1− x Yb x S 2 ( x = 0, 0.01) single crystals are investigated. It is established that partial substitution of ytterbium for gallium leads to (i) an increase in the electrical resistivity of the samples, (ii) a shift in the maximum of the intrinsic photocurrent toward the long-wavel…
Dielectric properties of the relaxor films are theoretically investigated with the Monte Carlo simulation. We find that the size effect on the dielectric susceptibility of films is neglectable while the influence of the surface layer of the film is overlooked. On the contrary, while the surface layer is explicitly con…
Recent studies involving porphyrin systems bearing fused five-membered rings are reviewed, these including pyrrolo[3,4-b]porphyrins and fused metallocenoporphyrins. Diels-Alder cycloadditions between pyrroloporphyrins, to give benzoporphyrins, are discussed. The syntheses of mono-, and the two regioisomers (adj- and o…
A novel electrically conductive photoresist has been formulated to fabricate microcomponents. The developed conductive photoresist is based upon SU-8 photopolymer, an insulating negative-tone epoxy, in which protonically doped polyaniline (PANI) nanoparticles have been dispersed to enhance the electrical properties. T…
In Gd1−x SrxMnO3 (x = 0.5, 0.6, 0.7) single crystals, a change in electric polarization (ΔP ∼ 100 μK/m2) is found to accompany the suppression of the charge-ordered spin-glass state and the transition to the ferromagnetic conducting phase (H cr ∼ 100 kOe at 4.5 K). The transition is also characterized by jumps in magn…
Os polietilenos lineares de baixa densidade (PELBD) são uma classe de polietilenos com cadeias lineares contendo somente ramificações de cadeia curta devido à inserção de uma alfa-olefina durante as reações de copolimerização com o eteno. As alfa-olefinas comumente utilizadas são o 1-buteno, o 1-hexeno e o 1-octeno. D…
Abstract The effect of a large amount of precipitated amorphous white silica nanofiller, pre-treated with bis[3-triethoxysilylpropyl-)tetrasulfide (TESPT), on the mechanical properties of a sulfur-cured natural rubber (NR) was studied. TESPT chemically adheres silica to rubber and also prevents silica from interfering…
Neste trabalho foi feito um estudo de tendências tecnológicas em nanotecnologia aplicado ao setor de materiais poliméricos, com base em informações extraídas de documentos de patentes. Foi usada como fonte de dados o banco de patentes da USPTO (United States Patent Trademark Office). Os dados foram obtidos via web, ut…