Materials Literature
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Silica fume is a pozzolanic addition specially used to get high resistance concrete. Present Spanish standards on additives dictate that silica fumes have to comply with specific requirements when used as concrete addition. Once it has been proved they comply with those requirements, microsilicas of different characte…
Near-band-edge cathodoluminescence of doped diamonds was studied at low temperatures. The doped diamonds were prepared either during the CVD growth of the diamond films by adding boron, phosphorus, or lithium sources to the reaction gases, or alternatively by ion implantation of boron, phosphorus, sodium, or arsenic.…
The time-averaged interaction force exerted by an acoustic field between two gas bubbles, known as the secondary Bjerknes force, is derived with an accuracy up to a component induced by the second harmonic of bubble oscillations. The surrounding medium is assumed to be an incompressible viscous liquid and the distance…
A mechanical alloying process is introduced to produce nanocrystalline metal hydride. The mechanical alloying process has recently emerged as a novel technique for producing alloy powders whose structures are nanocrystalline. alloys were prepared using planetary ball mill starting from mixtures of elemental powders. N…
Reference x-ray powder patterns and the crystal structures of the lanthanide compounds, BaR2ZnO5, in which R = La, Nd, Sm, Eu, Gd, Dy, Ho, Y, Er, or Tm, were determined by the x-ray Rietveld refinement technique. A structural trend was confirmed for this series of compounds. The compounds with smaller ionic radii (R =…
For biologically interfaced sensing applications, nanostructured porous silicon (PSi) is a very promising candidate, since mammalian cells can be cultured directly onto it. The development of cell culture systems for a PSi–cell interface is described, together with the development of a more “nature-identical” simulate…
The conditions, i.e., the interparticle potentials, for which vapor–liquid coexistence is supplanted by microphase separation are examined. The liquid phase is found for potentials with a steeply repulsive core and an attraction of not-too-short a range. To this potential we add a repulsion of longer range than the at…
Open‐cell ceramic foams were obtained from the pyrolysis, at 1000° to 1200°C under nitrogen, of a preceramic polymer (a silicone resin) and blown polyurethanes. The morphology of the expanded polyurethane was reproduced in the final architecture of the ceramic foam. The foams produced in this way consisted of an amorp…
We report a first principles study of the structure and the vibrational properties of the Si(100)-H(2 \times 1) surface in an electric field. The calculated vibrational parameters are used to model the vibrational modes in the presence of the electric field corresponding to a realistic STM tip-surface geometry. We fin…
We compare time-dependent solutions of different phase-field models for dendritic solidification in two dimensions, including a thermodynamically consistent model and several ad hoc models. The results are identical when the phase-field equations are operating in their appropriate sharp interface limit. The long time…
In this work, the many-spin interactions taking place in ${\mathrm{Mn}}_{12}$ large-spin clusters are extensively studied using the 8-spin model Hamiltonian, for which we determine the possible parameters based on experimental data. Account of the many-spin excitations satisfactorily explains positions of the neutron…
Nanocrystalline cerium(IV) oxide (CeO 2 ) powders were prepared by heating solutions of cerium(IV) salts in the presence of urea under hydrothermal conditions at 120° to 180°C. The effects of the concentration of urea and hydrothermal treatment temperature on the morphology and crystallite size of the synthesized part…
Abstract The construction and operation of a spray drier is described where the spray is produced using an air brush, essentially a miniature spray gun. The spray-dried products consist of spheres 50–60 µm in diameter and typical product recoveries are 80%, a marked improvement over simple two-nozzle systems. The spra…
The formation and decay of the optical hole (bleach) for 4 nm CdSe nanoparticles (NPs) with adsorbed electron acceptors (1,4-benzoquinone and 1,2-naphthoquinone) and the rise and decay of the reduced electron acceptors formed after interfacial electron transfer from the CdSe NPs were investigated by femtosecond laser…
We study the emission line shapes of single CdSe nanocrystallite quantum dots. Single dot line shapes are found to result from rapid spectral shifting of the emission spectrum rather than the intrinsic physics of the quantum dot. A strong dependence of single dot line widths on excitation intensity, wavelength, temper…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTUnusual Kinetic Stability of a Ground-State Singlet Oxomanganese(V) Porphyrin. Evidence for a Spin State Crossing EffectNing Jin and John T. GrovesView Author Information Department of Chemistry, Princeton University Princeton, New Jersey 08544 Cite this: J. Am. Chem.…
The electropolymerization of different azines from aqueous solutions was investigated. The structure of monomers was systematically varied changing both the nature of the second heteroatom and the substituents in the aromatic rings. Considering the electropolymerization process and the properties of the resulting poly…
Communication: The brightness and efficiency of liquid crystal displayscan be improved by replacing the second polarizer and color filter with a single oriented polyethylene film containing monodisperse silver nanoparticles, as revealed in the Figure. The preparation of the films, which exhibit bright colors and appea…
We report a novel method for the synthesis of stable, OH free zinc oxide quantum dots, using an electrochemical route. The optical properties of these quantum dots were studied at room temperature, by taking the optical absorption and luminescence spectra. The band gap luminescence is predominant in ZnO quantum dots s…
Self-assembly of cyclic bis-urea compounds takes place even at low concentrations to form very thin fibers which give a three-dimensional network in the solvent. The X-ray structure indicates that the molecules assemble into one-dimensional chains in which each unit forms eight hydrogen bonds with its neighbors (see p…