Materials Literature
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Block copolymer micelles have been employed as nanosized reactors in which single gold particles were formed. Films can be produced by a process consisting of four steps. Monolayers of hexagonally assembled micelles (see Figure and this month's cover) can be prepared with rather regularly arranged, size‐controlled Au…
The fundamental theory of the UHF method for detecting partial discharge (PD) in gas insulated substations (GIS) is presented. The effects of position, size, current amplitude and pulse shape of the PD source on the UHF signal can be predicted using this theory. Excitation of propagating electromagnetic waves by a PD…
Polymerized (F-)actin is induced to form bundles by a number of polycations including divalent metal ions, Co(NH3)63+, and basic polypeptides. The general features of bundle formation are largely independent of the specific structure of the bundling agent used. A threshold concentration of polycation is required to fo…
A classical model for the lattice distortions of ${\mathrm{La}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathit{A}}_{\mathit{x}}$${\mathrm{MnO}}_{3}$ is derived and, in a mean field approximation, solved. The model is based on previous work by Kanamori and involves localized Mn d electrons (which induce tetragonal dist…
What can stop the mountain of discarded plastic packaging from growing? One solution to be considered is the development and use of biodegradable polymers. The advantages and drawbacks of various biodegradable plastics, water‐soluble polymers, and natural and semisynthetic polymers are outlined in tis review. The Figu…
A predictive model was developed for uniform carbon dioxide (CO2) corrosion, based on modeling of individual electrochemical reactions in a water-CO2 system. The model takes into account the electrochemical reactions of hydrogen ion (H+) reduction, carbonic acid (H2CO3) reduction, direct water reduction, oxygen reduct…
We present mathematical results which dramatically enhance the computational efficiency of the phase-field method for modeling the solidification of a pure material. These results make it possible to resolve a smaller capillary length to interface thickness ratio and thus render smaller undercooling and three-dimensio…
The coupled-wave method formulated by Moharam and Gaylord [ J. Opt. Soc. Am.73, 451 ( 1983)] is known to be slowly converging, especially for TM polarization of metallic lamellar gratings. The slow convergence rate has been analyzed in detail by Li and Haggans [ J. Opt. Soc. Am. A10, 1184 ( 1993)], who made clear that…
Carbon nanotubes subject to large deformations reversibly switch into different morphological patterns. Each shape change corresponds to an abrupt release of energy and a singularity in the stress-strain curve. These transformations, simulated using a realistic many-body potential, are explained by a continuum shell m…
Publised data on the activity and selectivity of titanium-containing catalysts of esterification and transesterification reactions are surveyed. The influence of the nature of ligand and of the composition of the medium on the activity of catalysts is shown. The selectivity of the catalysts is considered from the view…
The characteristic features of the synthesis and properties of cardo polyheteroarylenes (polyarylates, aromatic polyethers, polyamides, polyimides, polyoxadiazoles, and others) are examined and surveyed. It is shown that cardo polymers containing bulky side-groups, linked via cyclic groups to the polymer main chain, h…
Molecular dynamics calculations and optical spectroscopy measurements of weakly active infrared modes are reported. The results are qualitatively understood in terms of the "motional diminishing" of IR lines, a process analogous to the motional narrowing of a nuclear magnetic resonance (NMR) signal. In molecular solid…
Alkaline-sulphate activation processes of a Spanish granulated blast furnace slag (Avilés, Ensidesa) have been studied. Activator solutions used were: deionized water (as reference solution), Ca(OH)2 (3,5∙10-3N), NaOH (1N), Na2CO3 (2N), CaSO4∙2H2O (3,0∙10-3N) at 25ºC. The influence of the nature of alkaline or sulphat…
Algae are ubiquitous; a multitude of species ranging from microscopic unicells to gigantic kelps inhabit the world's oceans, freshwater bodies, soils, rocks, and trees, and are responsible for most of the global production of organic matter by photosynthesis. They thus play a fundamental role in the world's ecosystems…
Poly(ethylene terephthalate) (PET) is a useful high-temperature plastic. Its shortcoming is that it has poor impact-strength properties. The impact strength of this polymer was dramatically improved by blending with a copolyester thermoplastic elastomer, or an acrylate core/shell elastomer. The addition of triphenyl p…
We report the first very low temperature (from 93 mK to 7.3 K) specific heat data of a modulated incommensurate dielectric (Cl${\mathrm{C}}_{6}$${\mathrm{H}}_{4}$${)}_{2}$S${\mathrm{O}}_{2}$. They reveal three different contributions in excess of that of normal acoustic phonons: low frequency excitations predominant b…
We have examined structural instabilities and elastic anomalies in CuCl via first-principles calculations and find that its crystal structure is not ideal zinc blende but that correlated displacements of groups of four Cu atoms lead to a more stable configuration. About 20% of the Cu atoms are estimated to be affected…
We develop a microscopic model for the mixed alkali effect in crystals of the $\ensuremath{\beta}$- and ${\ensuremath{\beta}}^{\ensuremath{'}\ensuremath{'}}$-alumina type, which is based on the formation of certain mobile defects and the fact that different types of mobile ions have a different preference to become pa…
We present calculations using a simple model of radiative recombination in 2D slabs, 1D wires, and 0D spheres of hydrogenated amorphous silicon (a-Si:H) showing a significant size dependence of the photoluminescence. Room-temperature peak emission energies ≳1.8 eV and efficiencies near unity are possible in a-Si:H sph…
These results reflect what is believed to be the first observation of electron emission from carbon-doped boron nitride (BN). The n-type BN films were synthesized on n-type polycrystalline diamond on (100)Si using reactive laser ablation. The electron emission current density measured at room temperature shows a power…