Materials Literature
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This work describes the comparison of experimental measurements of electron beam spread in the environmental scanning electron microscope with model predictions. Beam spreading is the result of primary electrons being scattered out of the focused beam by interaction with gas molecules in the low-vacuum specimen chambe…
Abstract Centrifuge extraction and Rotavapor recovery were used to determine the effect of solvent type (trichloroethylene and four n-propyl bromide products) on recovered asphalt binder properties. Mix variables included three binders mixed with each of two aggregate sources (one gradation). When recovered binder pro…
Cr 2 N, CrN, and their mixtures (with desired fractions) have been prepared via self‐propagating high‐temperature synthesis (SHS) under a controlled nitrogen pressure, followed by hot isostatic pressing at 1300°C and 196 MPa under an atmosphere of argon gas. The combustion temperature increased as the nitrogen pressur…
This paper describes the vacuum ultraviolet (VUV) radiation durability screening testing of thin (12.7–25.4 μm) polyimide films proposed for use on the Next Generation Space Telescope (NGST) sunshield. Materials included in this screening test were Kapton®E, Kapton®HN, Upilex®S, CP1, CP1 with vapour deposited aluminiu…
Calculations for a set of nuclear multifragmentation data are made using a canonical and a grand canonical model. The physics assumptions are identical but the canonical model has an exact number of particles, whereas the grand canonical model has a varying number of particles, hence, is less exact. Interesting differ…
An analytic link between the oxygen partial pressure and the concentrations of the point defects for given temperatures and A/B conditions is presented for perovskites. A clear distinction between three different conditions is made. These are the sintering conditions, an intermediate metastable state, and a low‐temper…
Two series of related poly(oxadiazole-amide)s have been synthesized by solution polycondensation reaction of aromatic diamines containing preformed 1,3,4-oxadiazole rings with diacid chlorides having silicon or hexafluoroisopropylidene groups. All these polymers were soluble in polar amidic solvents, such as N-methylp…
Abstract Red phosphorus contained in non‐irradiated polyamide‐6 at concentrations up to 12.5 does not significantly improve the fire resistance of the polymer. It weakens the thermal stability of the polymer as reflected by a decrease in the onset temperature for mass loss from 407°C to 363°C, but causes char formatio…
The selection of fouling resistances to design plate-and-frame heat exchangers is usually based on experience or guesswork. The primary aim of this study was to compare fouling resistances for plate heat exchangers with values obtained in a parallel double-pipe heat exchanger under comparable operating conditions. The…
Several composites with short glass fiber of a copolymer of ethylene and 1-octene, synthesized with a metallocene catalyst, have been prepared, up to a fiber content of 60 wt.-%. The effect of the fiber on the structure and mechanical behavior has been analyzed. Though the peak melting and crystallization temperatures…
A tenacificação da matriz vítrea de poliestireno (PS) pela adição de borracha polibutadiênica, que tem como conseqüência um aumento de sua resistência ao impacto, origina um polímero com características singulares, o Poliestireno de Alto Impacto (HIPS). Durante a polimerização in situ de estireno em uma solução de bor…
The visualization of mesopores and defects in porous molecular sieves, as well as of the incorporation dynamics and spatial distribution of guest molecules, is achieved by optical confocal microscopy of single crystals immersed in solutions of fluorescent dyes. The Figure shows a fluorescence image of a silicalite cry…
The bending and tapering of microtwin needles at the interface between two martensite laminates in ${\mathrm{Ni}}_{65}{\mathrm{Al}}_{35}$ are addressed. A theory is presented, based on the assumption that the microstructure is essentially stress-free; it predicts a linear relationship between the bending and tapering…
Single crystals of γ-Li 3 PO 4 have been grown from flux. The 4 × 8 × 9-mm crystals have the cleavage along the [010] and [120] directions. The anisotropy in ionic conductivity in the grown crystals, ((σ ‖ a )/(σ ‖ b ) = 2.5 and (σ ‖ a )/(σ ‖ c ) = 1.3), is explained by specific features of the γ-Li 3 PO 4 structure.
Direct formation of a large vacancy loop by displacement cascade in α-Fe has been observed for the first time in a molecular dynamics (MD) computer simulation study. This phenomenon occurred in one anomalous run out of 100 simulations of 50 keV primary knock-on atom energy cascades, in which one large displacement cas…
Ab initio coupled perturbated Hartree−Fock calculations, using 6-31G** basis sets, on a heterocyclic zwitterionic molecule with a σ-spacer between the donor and the acceptor ring shows a static first hyperpolarizability (β 0 ) of around 240 × 10 -30 esu. Substitution of electron withdrawing functional groups, such as…
Optical absorption of nanocrystalline thin films can be influenced by the presence of both porosity and grain size effects. If both are present simultaneously, their effects are difficult to separate. In this study it is shown that the combination of uv-vis transmittance and reflectance measurements on porous CeO2 fil…
Monte Carlo simulations have been performed for the linear tangent hard sphere model. The models considered in this work consisted of m=3, 4, 5, 6, and 7 monomer units. For the models m=3 and m=4 we find an isotropic fluid and an ordered solid. For the m=5 model we find the sequence of phases isotropic–nematic–smectic…
We discuss mathematical models of capillary flow in complex geometries representative of the void spaces formed between fibers in a textile yarn. Moisture transport in textile yarns and fabrics is an important factor affecting physiological comfort. We have extended an existing analytical model for capillary flow in c…
This paper discusses environmental management and technical considerations for the decommissioning, closure and reclamation of a mine site. The management and technical aspects discussed include planning; decommissioning, closure and reclamation design basis and performance measures; implementation; monitoring; and fi…