Materials Literature
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We present a first-principles study of 180\ifmmode^\circ\else\textdegree\fi{} ferroelectric domain walls in tetragonal barium titanate. The theory is based on an effective Hamiltonian that has previously been determined from first-principles ultrasoft-pseudopotential calculations. Statistical properties are investigat…
We study the interplay between an isostructural critical point and dislocation-mediated two-dimensional melting, using a combination of Landau and continuum elasticity theory. If dislocations are excluded, coupling to the elastic degrees of freedom leads to mean-field critical exponents. When dislocations are allowed,…
We have fabricated an all‐polymer battery utilizing the redox properties of electrically conducting polymers for the anode and cathode in conjunction with an ionic conducting polymer gel electrolyte. The anode and cathode consist of pyrrole electropolymerized onto a graphite fiber substrate resulting in a high‐surface…
Microbial synthesis of copolymers of [R]-3-hydroxybutyrate (3HB) and 4-hydroxybutyrate (4HB), P(3HB-co-4HB), by Alcaligenes eutrophus, Alcaligenes latus, and Comamonas acidovorans from various carbon sources has been studied. The copolyester compositions varied from 0 to 100 mol% 4HB, depending on the microorganism an…
A mesoscopic or coarse-grained approach is presented to study thermo-capillary induced flows. An order parameter representation of a two-phase binary fluid is used in which the interfacial region separating the phases naturally occupies a transition zone of small width. The order parameter satisfies the Cahn–Hilliard…
Abstract Assemblies of glycoproteins from within the mineralized tissues of sea urchins and mollusks both interact in vitro in a similar manner with growing calcite crystals. A protein‐rich fraction, a polysaccharide‐rich fraction, and a fraction composed of densely glycosylated peptide cores were obtained by chemical…
Abstract A new Monte Carlo simulation approach has been developed to describe electron scattering and secondary electron generation processes in solids. This approach is based on the uses of Mott's elastic scattering cross section and Penn's dielectric function. A very good agreement has been found on the energy distr…
The intrinsic biological and physiochemical characteristics of collagen have been exploited to prepare a variety of commercially available medical products spanning many medical specialties. The properties of purified collagen can be modified to obtain forms which comply to specific applications. In particular, collag…
Zinc oxide films of good quality have been cathodically deposited on NESA glasses from aqueous 0.03 to 0.1 mol/liter zinc nitrate electrolyte at 335 K.The films had a wurtzite structure and an optical bandgap energy of 3.3 eV which is characteristic of ZnO.
A biomimetic templating approach to the synthesis of lamellar silicas is demonstrated. The procedure is based on the hydrolysis and cross-linking of a neutral silicon alkoxide precursor in the interlayered regions of multilamellar vesicles formed from a neutral diamine bola-amphiphile. Unlike earlier surfactant-templa…
Abstract Vision and other light‐triggered biochemical transformations in plants and living organisms represent a sophisticated biological processes in which optical signals are recorded and transduced as (physico)chemical events. Photoswitchable biomaterials are a new class of substances in which optical signals gener…
Composite structures in which amorphous and crystalline phases coexist are formed by some organisms. The spicules of the sponge Clathrina are shown to be composed of a crystalline calcitic core and an outer layer of amorphous CaCO 3 (see figure). The latter material, normally a highly unstable mineral, is stabilized i…
Shear-induced crystallization of isotactic polypropylene (iPP) homo-, block, and random copolymers was studied and compared to that in quiescent melt. It was evidenced by means of the thermo-optical technique that melt-shearing, caused by fiber pulling, is associated with the development of α-row-nuclei. The surface o…
Corrosion of steels causes a loss of about 121 billion dollars annually and half the iron produced at present is used for the replacement of the existing deteriorated structures. Corrosion, being an electrochemical phenomenon, can be tackled through the use of electrochemistry and conducting polymers. Stainless steels…
Abstract The equilibrium H- and O-isotope fractionations can be approximated by the following equations which are based on experimental, empirical and/or theoretical data: Hydrogen: 1000 ln α kaolinite-water = −2.2 × 10 6 × T −2 − 7.7 Oxygen: 1000 ln α kaolinite-water = 2.76 × 10 6 × T −2 − 6.75 1000 ln α smectite-wat…
An existence result for the Cahn–Hilliard equation with a concentration dependent diffusional mobility is presented. In particular, the mobility is allowed to vanish when the scaled concentration takes the values $ \pm 1$, and it is shown that the solution is bounded by 1 in magnitude. Finally, applications of our met…
Electrochemical polymerization of aniline, on a Pt foil electrode coated with poly(methyl methacrylate) (PMMA), produces a homogeneous, free-standing, flexible, and conductive polymer film. The conductivity of the films depends on the aniline content and reaches 0.1–0.2 S/cm for films having aniline content of 15% or…
Rubber particle size is an important issue in toughening of engineering thermoplastics. Use of core-shell impact modifiers offers the advantage of a predetermined particle size; however, these particles must be appropriately dispersed in the matrix polymer to be effective for toughening. Recent work has shown that cor…
To improve the performance of rubber compounds using precipitated silica as a reinforcing filler, the silica surface was directly modified by (1) adsorption of a surfactant onto the surface, (2) adsolubilization of an organic monomer, (3) in situ polymerization of the monomer in the surfactant bilayer, and (4) partial…
Blends of chitosan with strongly crystalline polyamides (nylon-4 and nylon-6) and weakly crystalline polyamides (caprolactam/laurolactam and Zytel®) were investigated. Phase behavior, morphology, interactions with water, mechanical properties, and catalytic reactivity were studied. Films were made from formic acid sol…