Materials Literature
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Abstract Ce/Al- and La/Al-pillared smectites were prepared by cation exchange of bentonite, saponite and laponite with hydrothermally treated (130–160 °C for 16–136 h) solutions containing mixtures of aluminumchlorohydrate (ACH) and Ce 3+ -/and La 3+ -salts. After calcination at 500 °C, the pillared products are chara…
The synthesis of some water-insoluble synthetic polyelectrolyte complexes formed between a weak polyanion and a strong polycation was followed. Sodium salts of poly(acrylic acid) and of some copolymers of acrylic acid with itaconic acid or maleic acid were used as anionic polymers. Cationic polyelectrolytes with quate…
We study the phenomena associated with the low-velocity impact of two solid discs of equal size using a cell model of brittle solids. The fragment ejection exhibits a jet-like structure the direction of which depends on the impact parameter. We obtain the velocity and the mass distribution of the debris. Varying the r…
This paper deals with optimization of a class of linear dynamic systems with n states and m control inputs, commanded to move between two fixed states in a prescribed final time. This problem is solved conventionally using Lagrange’s multipliers and it is well known that the optimal solution satisfies 2n first-order l…
Abstract The fracture response of injection molded short glass fiber (GF) reinforced and rubber‐toughened poly(butylene terephthalate) (PBT) composites has been characterized by the fracture toughness (K c ) and energy (G c ), measured on static‐loaded compact tension (CT) specimens. The related failure of the composi…
Abstract This report describes the synthesis of a water soluble polyaniline through a biochemical synthetic route. The oxidative free radical coupling mechanism for the synthesis of poly( p ‐aminobenzoic acid) is catalyzed by horseradish peroxidase in the presence of hydrogen peroxide. The resulting polymer is electro…
Abstract : A set of partial differential equations describing time-dependent heat and mass transfer through porous hygroscopic materials was developed which includes factors such as the swelling of the solid due to water inhibition, and the heat of sorption evolved when the water is absorbed by the polymeric matrix. A…
End-grafted polymer brush exposed to strong shear solvent flow is studied. Under strong enough shear flow, the shear force is nonlinear with the blob size depending on the shear force and not on the monomer volume fraction $\ensuremath{\varphi}$. We derive the crossover force scale separating the weak and strong shear…
We present a recently developed nonlinear model based on the constitutive undercooling mechanism to explain oscillatory zoning in plagioclase. It uses diffusion-controlled growth kinetics coupled with a nonlinear partition relation. Regular oscillatory zoning, period doubling sequence and chaotic zoning are possible f…
Abstract The properties of new fluorescent dyes (derivatives of unsaturated 1,8-naphthalimide) are stud-ied. Spectral characteristics of the dyes are recorded in both isotropic (ethanol, dioxane) and anisotropic (nematogenic liquid crystal mixture ZLI 1840) media. The optical, electro-optical, and thermodynamical prop…
Abstract The preparation and characterization of Ti-pillared acid-activated clays (designated Ti PAACs) and conventional Ti-pillared clays (designated Ti PILCs) are described. Preliminary catalytic results show that these materials possess remarkably enhanced abilities to catalyse the dehydration of pentanol compared…
LARC ™ -RP46 resin system is a PMR type polyimide and is prepared by replacing methylenedianiline in the PMR-15 composition with 3,4′-oxydianiline. This resin system retains the same processing characteristics as PMR-15 but also offers enhanced fracture toughness. Rheological measurements were conducted on pre-imidize…
Abstract An indolylfulgide having a 1-(1,2-dimethyl-3-indolyl)-2,2,2-trifluoroethylidene group on the succinic anhydride showed an excellent resistivity towards the repetition of photochromic transformation between the photostationary states of UV- and visible-light irradiation both in toluene and in a PMMA film under…
Particle uptake and translocation occur at specific sites in the gastrointestinal tract. Several drugs are also absorbed from solution only through narrow "windows' in the small intestine. In these circumstances, optimum therapeutic benefit would be obtained if the active agent was targeted to the appropriate site in…
Poly(etherurethane) elastomers are useful materials in medical devices because of their mechanical properties and biocompatibility. However, it is necessary to stabilize these elastomers against the oxidation of their ether soft segments. Synthetic antioxidants such as Santowhite and Irganox are often satisfactory; ho…
A series of Pd–Cu/KL zeolites with varying Pd : Cu ratios have been studied by a combination of FTIR and XANES. XANES indicates that only one PdCu alloy is formed for all samples and that the bulk of the alloy is not modified by extended periods under CO/H2at elevated temperatures. A combination of low temperature ads…
Abstract From neutron powder diffraction intensities it is often problematic to distinguish between centrosymmetry and non-centrosymmetry. X-ray single crystal diffraction may be more accurate. In this paper we compare refinement results of crystal structures on the basis of neutron powder data of orthorhombic NdGaO 3…
In water, the inertial collapse of a bubble is more violent after expansion by a negative acoustic pressure pulse than when directly compressed by a positive pulse of equal amplitude and duration. In tissues, gas bodies may be limited in their ability to expand and, therefore, the relatively strong effectiveness of ne…
The effect of various degrees of deformation was investigated at specific locations in the stress-strain curve under compression on the corrosion resistance of a wrought Ni-Ti alloy with a martensite to austenite transformation peak of 110 degrees C. Two metallurgical conditions were evaluated: 30% cold drawn and anne…
The water absorption properties of a PE-CVD (plasma-enhanced chemical vapor deposition) fluorine-doped SiO 2 film with a low dielectric constant were studied. It was concluded that highly stable F-doped SiO 2 film was obtained at F contents from 2.0% to 4.2% (3.2≤ k ≤3.6) using high-density plasma CVD. However, at F c…