Materials Literature
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A new beamline, fully dedicated to X-ray powder diffraction (XPD) measurements, has been installed after the exit port B of the bending magnet D10 at the Brazilian Synchrotron Light Laboratory (LNLS) and commissioned. The technical characteristics of the beamline are described and some performance indicators are liste…
Abstract Hybrid thin films of conjugated polymers and CdSe nanoparticles have been fabricated by using a layer‐by‐layer (LbL) approach driven by covalent coupling reactions. This method permits facile covalent crosslinking of the polymer/nanoparticle interlayers in common organic solvents, which provides a general rou…
We extensively study the phase diagram of a diblock copolymer melt confined in a cylindrical nanopore using real-space self-consistent mean-field theory. We discover a rich variety of new two-dimensional structures that have no analogue in the unconfined system. These include nonhexagonally coordinated cylinder phases…
A recently proposed microscopic activated barrier hopping theory [K. S. Schweizer and E. J. Saltzman, J. Chem. Phys. 119, 1181 (2003)] of slow single-particle dynamics in glassy liquids, suspensions, and gels is derived using nonequilibrium statistical mechanics. Fundamental elements underlying the stochastic nonlinea…
[reaction: see text] Oxidation of alkynes to alpha-dicarbonyl derivatives through a convenient one-pot procedure via a Brønsted acid-promoted "hydration" and a DMSO-based oxidation sequence has been achieved in high yields. The scope and limitations of the reaction have also been investigated.
The 19ID undulator beamline of the Structure Biology Center has been designed and built to take full advantage of the high flux, brilliance and quality of X-ray beams delivered by the Advanced Photon Source. The beamline optics are capable of delivering monochromatic X-rays with photon energies from 3.5 to 20 keV (3.5…
At low pressure, free surfaces play a crucial role in the melting transition. Under pressure, the surface of the sample is acted upon by some pressure transmitting medium. To examine the effect of this medium on melting, we performed Monte Carlo simulations of a system of argon atoms in the form of a slab with two bou…
Based on experimental 59Co-NMR data in the temperature range between 0.1 and 300 K, we address the problem of the character of the Co 3d-electron based magnetism in Na0.7CoO2. Temperature dependent 59Co-NMR spectra reveal different Co environments below 300 K and their differentiation increases with decreasing tempera…
The Thomas-Fermi (TF) approximation for the static dielectric constant of a three-dimensional electron liquid can be derived from minimizing the TF local-density approximation for the kinetic-energy functional. Here we show that this connection between energy functionals and model dielectric constants is not an artifa…
We study solid surface morphology created by off-normal ion-beam sputtering with an atomistic, solid-on-solid model of sputter erosion. With respect to an earlier version of the model, we extend this model with the inclusion of lateral erosion. Using the 2-dimensional structure factor, we found an upper bound $μ\simeq…
The work describes the capabilities of Laser Scanning Microscopy (LSM) as a spatially resolved method of testing high_Tc materials and devices. The earlier results obtained by the authors are briefly reviewed. Some novel applications of the LSM are illustrated, including imaging the HTS responses in rf mode, probing t…
We propose and demonstrate a spatial partition method for the high-frequency photo-response of superconducting devices correlated with inductive and resistive changes in microwave impedance. Using a laser scanning microscope, we show that resistive losses are mainly produced by local defects at microstrip edges and by…
The flow anisotropy of a concentrated colloidal suspension at the jamming transition is studied. It is shown that the use of rough spherical particles reduces the hydrodynamic lubrication forces between adjacent colloids and makes possible the study of the stress tensor anisotropy. At low shear rates, the suspension e…
The work in this paper analyses the applicability of carbon nanotube (CNT) bundles as interconnects for VLSI circuits, while taking into account the practical limitations in this technology. A model is developed to calculate equivalent circuit parameters for a CNT-bundle interconnect based on interconnect geometry. Us…
The propagation of an interfacial crack along a heterogeneous weak plane of a transparent Plexiglas block is followed using a high resolution fast camera. We show that the fracture front dynamics is governed by local and irregular avalanches with very large size and velocity fluctuations. We characterize the intermitt…
White light-emitting diodes (WLEDs) were fabricated by combining blue InGaN chips with luminescent colloidal core-shell CdSe-ZnSe quantum dots (QDs). The core-shell CdSe-ZnSe QDs synthesized by thermal deposition approach exhibited high photoluminescence efficiency with a quantum yield more than /spl sim/40%, and size…
We describe a rapid, room temperature, reverse emulsion polymerization method to chemically synthesize bulk quantities of micrometers long nanotubes of electrically conducting poly(3,4-ethylenedioxythiophene) (PEDOT) having tube diam-eters in the range 50-100 nm. Composites of PEDOT nanotubes with noble metals, metal…
Fluorescent nanoparticles were isolated from both pristine and nitric acid-oxidized commercially available carbon nanotubes that had been produced by an electric arc method. The pristine and oxidized carbon nanotube-derived fluorescent nanoparticles exhibited a molecular-weight-dependent photoluminescence in the viole…
Novel bone-scaffolding materials were successfully fabricated by electrospinning from polycaprolactone (PCL) solutions containing nanoparticles of calcium carbonate (CaCO(3)) or hydroxyapatite (HA). The diameters of the as-spun fibers were found to increase with the addition and increasing amounts of the nanoparticles…
Recent efforts in scientific research in the field of peripheral nerve regeneration have been directed towards the development of artificial nerve guides. We have studied various materials with the aim of obtaining a biocompatible and biodegradable two layer guide for nerve repair. The candidate materials for use as a…