Materials Literature
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Quantum antidots are subnanometer scale vacancy clusters, the localized electronic structure of which can significantly alter the properties of a nanomaterial. We use positron spectroscopy to study vacancy clusters generated during the formation of gold nanoparticles via ion implantation in an MgO matrix. We observed…
This work addressed the bound train fraction of an adsorbing model polyelectrolyte ((dimethylamino)ethyl methacrylate, DMAEMA), for variations in pH, which altered the relative charge densities of the polymer and substrate (silica). In addition to the weakly basic and acidic natures of the polyelectrolyte and substrat…
Measuring the magnetization and the specific heat of ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{MnO}}_{3}$ single crystals with $0.11<~x<~0.15$ we have investigated the charge order (CO) transition in lightly doped manganites. Though the properties of the ferromagnetic insulating state at low tem…
The electronic energy-band structures of ordered ${\mathrm{Fe}}_{2}\mathrm{P}$-type intermetallic superconducting compounds $\mathrm{ZrRu}X$ $(X=\mathrm{P},\mathrm{A}\mathrm{s},\mathrm{S}\mathrm{i})$ have been calculated by the full-potential linearized augmented plane-wave method within the local-density approximatio…
The conformation of ethylene oxide segments has been found to vary when they are incorporated into triblock oligomers [H(CH 2 ) m (CH 2 CH 2 O) n (CH 2 ) m H] or microblock copolymers [−(CH 2 ) m (CH 2 CH 2 O) n −] x of ethylene (E) and ethylene oxide (EO) depending on the relative length ( m vs n ) of the sequences.…
The structures of thymine, 2′-deoxythymidine (dT), 5′-thymidinemonophosphate (TMP) and the anti-HIV drug 3′-azido-3′-deoxythymidine (AZT) are studied in this work in solid state, aqueous solution and when these molecules are adsorbed on Ag colloids by means of Raman and surface-enhanced Raman spectroscopy (SERS). The…
Conformational contributions to the heat capacity of the interacting system of polymer−water have been studied on the example of starch with and without low concentrations of water. This work continues a series of thermal analyses of biological materials. The heat capacity has been linked to its vibrational, external,…
A highly active and stable zirconia supported 12-tungstophosphoric acid catalyst is found to be 2-3 times more active in benzylation and acylation reactions than a tungstated zirconia catalyst.
Polymer-mediated self-assembly of functionalized Pd and SiO2 nanoparticles provides highly active hydrogenation and Heck coupling catalysts.
Syndiotactic polypropylene (sPP) was melt-quenched in an ice−water bath and directly drawn at 0 °C up to a draw ratio of 6. The oriented sample was kept in the cold bath for 10 days under tension, and then analyzed at room temperature either fixed or after releasing tension. The fully extended fiber showed by X-ray di…
A series of partially fluorinated (C 6 F 13 H-modified) polystyrene- b -1,2-polybutadiene (PS- b -1,2-PB) copolymers were prepared by the reaction of a model PS- b -1,2-PB copolymer with n -C 6 F 13 I followed by substitution of hydrogen for the iodine by hydrogenolysis. The morphologies and domain spacings of the ord…
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” opt…
Thermoplastic vulcanizates (TPVs) prepared by dynamic vulcanization are blends in which cross-linked rubber particles are finely dispersed in a thermoplastic matrix. These blend materials, which are in our case based on nylon-6 and EPDM rubber, show excellent strain recovery behavior, even though the matrix consists o…
Computer modeling of the variable-range-hopping (VRH) conductivity in two-dimensional systems has been done by a kinetic Monte Carlo method, which includes some new elements. Study of the temperature dependence of the conductivity, testing of the different scaling relations, and study of the size effect show the detai…
The role of proteins in biomineralization and the mechanism of eggshell formation are not well understood. We have isolated and purified the major protein, ansocalcin from goose eggshell matrix. The amino acid sequence study indicates that ansocalcin is homologous to the chicken eggshell protein, ovocleidin 17, and C-…
Tunneling junctions of stacked monolayers of uniform, organically functionalized ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$ nanocrystals of 5.5 nm average diameter were prepared. Current-voltage characteristics of the junctions were studied as function of temperature and magnetic field. An abrupt increase in the resistance w…
Supramolecular systems--their successes, problems, and potential--are discussed with allusion to specific examples.
We have constructed microscopic, structurally relaxed atomistic models of $\mathrm{Si}/{\mathrm{SiO}}_{2}$ superlattices. The structural distortion and oxidation-state characteristics of the interface Si atoms are examined in detail. The role played by the interface Si suboxides in raising the band gap and producing d…
Diffuse neutron scattering is a valuable tool to obtain information about the size and orientation of the polar nanoregions that are a characteristic feature of relaxor ferroelectrics. In this paper, we present new diffuse scattering results obtained on Pb(Zn1/3Nb2/3)O3 (PZN for short) and (1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO…
The wave function and binding energy for shallow donors in GaAs are calculated within the tight binding (TB) approach, for supercells containing up to two million atoms. The resulting solutions, coupled with a scaling law, allow extrapolation to the bulk limit. A sharp shallow-deep transition is obtained as the impuri…