Materials Literature
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Abstract More than activity, selectivity of catalytic reactions is the focus of research in the 21 st century. We review studies on model systems that address the issue of directing a catalytic reaction on disperse metal catalysts by controlling the specific surface site. Three examples are explored: methanol dehydrog…
Abstract The novel two‐ and three‐dimensional solid materials [Cu(en) 2 (H 2 O)]{PMo VI 8 V IV 6 O 42 [Cu(en) 2 ][Cu 0.5 (en)] 3 }·5.5H 2 O and H 3 {V V Mo VI 8 V IV 6 O 42 [Cu(en) 2 ] 4 }[MoO 4 ] 2 ·14H 2 O (en = ethylenediamine) have been hydrothermally assembled and structurally characterized. Both networks are bas…
The VLF transmitting system in Cutler, ME currently broadcasts at one frequency through a two-element antenna system. This study investigates simultaneous operation at 24.0 and 17.8 kHz. Detailed nonlinear PSPICE models were generated for the system including the amplifier triodes, saturable dynamic-tuning reactors, a…
This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 82260, "Matrix Acid Stimulation - A Review of the State of the Art," by Phil Rae, SPE, and Gino di Lullo, BJ Services Co., prepared for the 2003 SPE European Formation Damage Conference, The Hague, 13-14 May.
A new rubidium pentaborate is synthesized under hydrothermal conditions. Its crystal structure is studied by the heavy-atom method without any a priori knowledge of chemical formula. The chemical formula is Rb[B5O6(OH)4] · 0.5H2O, sp. gr. $$\bar P1$$ , lattice parameters a = 7.679(4) Å, b = 9.253(6) Å, c = 12.053(9) Å…
Chemical species during growth of carbon nanotubes (CNTs) in direct current-plasma-enhanced chemical vapor deposition were studied in detail using C3H4–NH3 and CO–NH3 mixtures through optical emission spectroscopy. In the C3H4–NH3 system, the relative intensities of CN (388.3 nm) and CH (431.4 nm) decreased and that o…
X-raying is used to study the structure of nanoporous carbon particles produced from carbides of various materials (SiC, TiC, Mo2C, and B4C) by chemical removal of carbide-forming elements. The X-ray diffraction patterns exhibit reflections in the double reflection angle ranges 2θ=23°–26° and 42°–44°. An analysis of t…
Abstract Two areas of networks modelling are described. The first is concerned with the application of a Monte‐Carlo (MC) algorithm to account fully for loop formation in RA 2 + R′B 3 and RA 2 + R′B 4 polymerisations. The resulting interpretation of experimental elastic moduli of HDI‐based polyurethane (PU) networks p…
(2003). Impact tensile properties of 6061 aluminium alloy to SUS 304 stainless steel friction-welded butt joints. Welding International: Vol. 17, No. 7, pp. 514-523.
Abstract Olefinic thermoplastic elastomers can be prepared by incorporating semi‐crystalline macromonomers (e.g. isotactic or syndiotactic poly(propylene), high‐density polyethylene) onto amorphous backbones (e.g. atactic poly(propylene), ethylene/ α ‐olefin copolymers). The macromonomer incorporation reaction can be…
The development of the chemistry of transition metal complexes formed by o -semiquinonato radical ligands has provided a useful topic for learning how to use chemical methods for obtaining systems with predetermined magnetic properties. Similar complexes can be used as building blocks for assembling magnetically coupl…
Scanning electron microscopy (SEM) images of polymer blends followed by digital image analysis is a rapid and easy method for the measurement of particle size and dispersion. The particle size determination is done with appropriate off-line image analysis software. However, it is necessary to understand how machine pa…
Abstract The correlation between the fiber structure and mechanical properties of two different poly(ethylene terephthalate) fiber types, that is, wool and cotton types produced by three producers, was studied. Fiber structure was determined using different analytical methods. Significant differences in the suprastruc…
The equilibrium partial pressures of vapour species generated in halide activated pack powder mixtures at high temperatures were calculated for a series of compositions using thermochemical analysis tools. The results obtained were applied to identify suitable activators and pack compositions for codepositing Al and S…
Abstract Poly(hydroxyalkanoate)s (PHA)s, as all melt‐processed polymers, may undergo thermal degradation at temperatures close to the melting point. The primary purpose of the present study is to screen out process variables on the basis of a factorial design for two variables at two levels. The investigated parameter…
We compare the diagonal /spl mu/ and off-diagonal /spl kappa/ permeability tensor components of magnetized polycrystalline ferrites given by the theoretical model of Gelin and Berthou with experimental ones at microwave frequencies. We used a broad-band and noniterative measurement technique recently developed within…
Abstract The effect of types of fillers on mechanical properties of rigid polyurethane composite samples was investigated. Polyurethane (PU) composites were prepared using a molasses polyol (MP, a mixture of molasses and polyethylene glycol, Mw=200) diphenylmethane diisocyanate (MDI) and fillers. The following plant p…
By applying the basic principles of metrology we discuss how to define the standards that any experimental method to measure resolution has to obey. Our results clearly indicate the need to apply a calibration procedure when designing algorithms to estimate resolution to satisfy accuracy requirements. Similarly, the p…
A discrete-component approach was taken to establish the operational feasibility of a novel, imaging, midinfrared, multispectral, polarimetric sensor for remote-sensing application. The sensor is designed to exploit the spectral and polarimetric characteristics of the scene as discriminants. Pixelated multispectral fi…
Covers advancements in spacecraft and tactical and strategic missile systems, including subsystem design and application, mission design and analysis, materials and structures, developments in space sciences, space processing and manufacturing, space operations, and applications of space technologies to other fields.