Materials Literature
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We suggest an approach to account for spatial (composition) and thermal fluctuations in "disordered" magnetic models (e.g. Heisenberg, Ising) with given spatial dependence of magnetic spin-spin interaction. Our approach is based on introduction of fluctuating molecular field (rather than mean field) acting between the…
A transit is the motion of a system from one many-particle potential energy valley to another. We report the observation of transits in molecular dynamics calculations of supercooled liquid argon and sodium. Each transit is a correlated simultaneous shift in the equilibrium positions of a small local group of particle…
It is shown and discussed how the conventional system of hydrodynamic equations for ferrofluids was derived. The set consists of the equation of fluid motion, the Maxwell equations, and the magnetization equation. The latter was recently revised by Felderhof [Phys. Rev. E, v.62, p.3848 (2000)]. His phenomenological ma…
A new magnetization equation recently derived from irreversible thermodynamics is employed to the calculation of an increase of ferrofluid viscosity in a magnetic field. Results of the calculations are compared with those obtained on the basis of two well-known magnetization equations. One of the two was obtained phen…
The contributions of the covalent bond energies of various atom pairs to the cohesive energy of MgB2 and AlB2 are analysed with a variant of our recently developed energy-partitioning scheme for the density-functional total energy. The covalent bond energies are strongest for the intralayer B-B pairs. In contrast to t…
First-principles density functional calculations reveal that aluminum can form planar chains in zigzag and ladder structures. The most stable one has equilateral triangular geometry with four nearest neighbors; the other stable zigzag structure has wide bond angle and allows for two nearest neighbors. An intermediary…
Nonlocal Hamiltonians are used widely in first-principles quantum calculations; the nonlocality stems from eliminating undesired degrees of freedom, e.g. core electrons. To date, attempts to couple nonlocal systems to external electromagnetic (EM) fields have been heuristic or limited to weak or long wavelength fields…
Convective instability in a ferrofluid layer heated from below or from above in the presence of a uniform vertical magnetic field is investigated theoretically. Convection is caused by a magnetic mechanism based on the temperature and concentration dependence of magnetization. An imposed temperature gradient establish…
We report the development of new bioactive coatings of biomaterials based on the alternate deposition of oppositely charged polyelectrolytes. We selected polylysine (PLL) and poly(glutamic acid) (PGA) for the polyelectrolytes and murine melanoma cells as a biological test model system. These cells respond specifically…
Nearly monodisperse (1.7 ± 0.2 nm) palladium nanoparticles were prepared within the interiors of three different generations of hydroxyl-terminated poly(amidoamine) (PAMAM) dendrimers. These dendrimer-encapsulated catalysts (DECs) were used to hydrogenate allyl alcohol and four α-substituted derivatives in a 4:1 metha…
Transition metal nanoparticles used in catalysis in solution are stabilized by capping the surfaces that are supposed to be used for catalysis. Determining how these two properties, that is, the catalytic activity and stability of nanoparticles, change as different capping materials are used is the aim of this work. P…
SBA-15 siliceous materials templated using triblock copolymers have recently received considerable attention because of their potential applications in catalysis and separations of large molecules. SBA-15 materials possess a regular hexagonal array of cylindrical channels of 5−30 nm in diameter and, unless specially t…
Abstract This study covers the preparation and characterization of perlite‐filled polypropylene (PP). The compositions of 15, 30, and 50 % by weight perlite–PP composites were prepared by melt‐mixing. The PP used in this study was either applied in the virgin form or γ‐irradiated in air at the doses of 10, 25, 50, and…
Local proton dynamics in several kinds of perovskite-type high-temperature protonic conductors were investigated by spectral hole burning spectroscopy. Spectral holes based on light-induced protonic motion were observed. By applying a temperature-cycling technique, the potential barriers for local protonic motion, whi…
A series of combined type thermotropic liquid crystalline (LC) poly(oxy-1,4-phenyleneoxyterephthaloyl)s bearing pendant cholesterol moieties attached to the backbone through oxyalkyleneoxy groups (hexamethylene, octamethylene, decamethylene, and dodecamethylene) of varying length, have been synthesized anew. And their…
Spectral properties of the tetrapyrrolidinyl PNP-lariat ether, L, and its complexes with K+, Na+, and Ag+ were investigated. Crystal structures of L and its complex with potassium iodide [KL]I were determined. Protonation constants of the ligand and formation constants of its complexes with Ag+, K+, and Na+ in aqueous…
This paper examines the use of direct nonradiative energy transfer (DET) experiments to determine the interface thickness in films of symmetric poly(styrene- b -methyl methacrylate) (PS−PMMA) block copolymers. The films were prepared from mixtures of two polymers of identical length and compositions, labeled at their…
The experimental heat capacity of ${\mathrm{Na}}_{8}{\mathrm{Si}}_{46}$ has been determined from 35--300 K, and its lattice parameters have been measured over the range 100--330 K. The experimental heat capacity and the thermal-expansion coefficient are compared with theoretical lattice-dynamical calculations for ${\m…
The composition ( φ ) and temperature dependence ( T ) of the monomeric friction factor ( ζ ) has been examined for styrene (S) and methyl methacrylate (MMA) in five SMMA diblock copolymers and the corresponding homopolymers. In all cases the degree of polymerization was approximately 150, sufficiently low to ensure t…
Abstract The mechanism of adhesive bonding of rubber to metal using an interlayer of bonding agent (adhesive) is discussed with respect to various physical and chemical events such as adsorption at the metal surface, chemical crosslinking within the adhesive, interdiffusion, and formation of interpenetrating networks…