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Congresos y Seminarios

Direct resistance profile for an electrical pulse induced resistance change device

We report the direct microscale resistance profile measurements on a symmetric thin-film electrical pulse induced resistance change (EPIR) device composed of a Pa0.7Ca0.3MnO3 (PCMO) active layer, using surface scanning Kelvin probe microscopy. The resistance switching is found to be an integration of the resistance ch…

Semiconductor Rings Fabricated by Self-Assembly of Nanocrystals

Three types of nonlinear organization schemes for creating ringlike semiconductors have been elucidated with the self-assembly of nanocrystals in aqueous phase under one-pot conditions. The synthetic architecture is based on morphological controls of primary nanocrystals which possess an intrinsic hexagonal symmetry.…

Photoluminescence of rare-earth-doped glasses

Summary. — Rare-earth elements are of interest in several high-tech and envi-ronmental application areas, the two major ones concerning magnetic and optical devices. In the latter field, one can exploit the unique photoluminescence properties of rare-earth ions to develop novel or advanced lasers and optical amplifier…

Retrosynthesis of Nacre via Amorphous Precursor Particles

Synthetic nacre morphologically indistinguishable from the natural archetype was synthesized with amorphous calcium carbonate precursors by confinement in the scaffold of the original insoluble nacre matrix. The precursors were generated using a synthetic polyelectrolyte highlighting the physicochemical aspects of bio…

Fluorescent Nanoparticle Probes for Cancer Imaging

Optical imaging technique has strong potential for sensitive cancer diagnosis, particularly at the early stage of cancer development. This is a sensitive, non-invasive, non-ionizing (clinically safe) and relatively inexpensive technique. Cancer imaging with optical technique however greatly relies upon the use of sens…

White-light emitting ZnO–SiO2nanocomposite thin films prepared by the target-attached sputtering method

ZnO–SiO 2 nanocomposite thin films were prepared using the target-attached RF sputtering method without substrate heating. The PL measurements showed that the SiO 2 films containing uniformly dispersed ZnO nanoparticles emit white light consisting of violet, blue, and green–yellow band emissions. The presence of the b…

Step Position Distributions and the Pairwise Einstein Model for Steps on Crystal Surfaces

The Pairwise Einstein Model (PEM) of steps not only justifies the use of the Generalized Wigner Distribution (GWD) for Terrace Width Distributions (TWDs), it also predicts a specific form for the Step Position Distribution (SPD), i.e., the probability density function for the fluctuations of a step about its average p…

Nematic-isotropic interfaces under shear: A molecular-dynamics simulation

We present a large-scale molecular-dynamics study of nematic-paranematic interfaces under shear. We use a model of soft repulsive ellipsoidal particles with well-known equilibrium properties, and consider interfaces which are oriented normal to the direction of the shear gradient (common stress case). The director at…

Electronic structure investigation ofTi3AlC2,Ti3SiC2, andTi3GeC2by soft x-ray emission spectroscopy

The electronic structures of epitaxially grown films of ${\mathrm{Ti}}_{3}{\mathrm{AlC}}_{2}$, ${\mathrm{Ti}}_{3}{\mathrm{SiC}}_{2}$, and ${\mathrm{Ti}}_{3}{\mathrm{GeC}}_{2}$ have been investigated by bulk-sensitive soft x-ray emission spectroscopy. The measured high-resolution Ti $L$, C $K$, Al $L$, Si $L$, and Ge $…

Inhibition of acid corrosion of mild steel by Telfaria occidentalis extract

Purpose To investigate the efficacy of Telfaria occidentalis extract as a corrosion inhibitor for mild steel in 2 M HCl and 1 M H 2 SO 4 solutions, respectively, and to assess the effect of temperature and halide additives on the inhibition efficiency. Design/methodology/approach Corrosion rate was monitored by carefu…

Two-dimensional hierarchical porous silica film and its tunable superhydrophobicity

Based on a monolayer polystyrene (PS) colloidal crystal, large-scale two-dimensional (2D) hierarchical porous silica (orderly arranged macropores and disordered mesopores in its skeleton) with a high specific surface area was fabricated by the sol–gel technique. Such material has demonstrated superhydrophilicity with…

Structure and Properties of Atomic Nanoclusters

# Introduction to Clusters # Experimental Production of Clusters # Van der Waals Clusters # Electronic and Atomic Shells in Metal Clusters # Electronic and Optical Properties of Simple Metal Clusters # Melting and Fragmentation of Metal Clusters # Bimetallic Clusters # Clusters of the Transition Metals # Magnetism # C…

Fabrication and characterisation of CdSe photonic structures from self-assembly

We demonstrate here a method to fabricate CdSe photonic crystal from a very cheap fabrication route of templated self-assembly. The hexagonal close-packed photonic crystals are formed by the electrochemical growth of CdSe through the interstitial spaces between polymer nano/micro sphere templates. The confocal voids c…

Low temperature magnetization and the excitation spectrum of antiferromagnetic Heisenberg spin rings

Accurate results are obtained for the low temperature magnetization versus magnetic field of Heisenberg spin rings consisting of an even number N of intrinsic spins s = 1/2, 1, 3/2, 2, 5/2, 3, 7/2 with nearest-neighbor antiferromagnetic (AF) exchange by employing a numerically exact quantum Monte Carlo method. A strai…

Silk sericin as a moisturizer: an in vivo study

BACKGROUND: Excessive transepidermal water loss (TEWL) is the one of the causes of dry skin, and skin moisturizers have been used to overcome it. AIM: The purpose of this research was to study the moisturizing effect of sericin, a silk protein. Because silk sericin has resemblance with the natural moisturizing factor…

Silicone rubber dielectrics modified by inorganic fillers for outdoor high voltage insulation applications

The paper discusses the mechanisms by which inorganic fillers in silicone rubber dielectrics enhance the properties of thermal conductivity, relative permittivity, and electrical conductivity making them useful in outdoor high voltage insulation applications. The addition of alumina trihydrate or silica fillers to sil…

Stimulated Emissions in Aligned CdS Nanowires at Room Temperature

Aligned CdS nanowires (NWs) were obtained through a simple thermal evaporation process with highly active CdS nanoparticles as the evaporation source. These NWs show prominent optical waveguides behavior under a continuous-wave (CW) laser excitation. Excitation intensity-dependent photoluminescence (PL) measurements s…

Part III: Surface-Enhanced Raman Scattering of Amino Acids and Their Homodipeptide Monolayers Deposited onto Colloidal Gold Surface

Surface-enhanced Raman scattering (SERS) spectra were measured for monolayers of various amino acids: L-methionine (Met), L-cysteine (Cys), L-glycine (Gly), L-leucine (Leu), L-phenylalanine (Phe), and L-proline (Pro) and their homodipeptides (Met-Met, Cys-Cys, Gly-Gly, Leu-Leu, Phe-Phe, and Pro-Pro) deposited onto a c…

Signal denoising techniques for partial discharge measurements

One of the major challenges of on-site partial discharge (PD) measurements is the recovery of PD signals from a noisy environment. The different sources of noise include thermal or resistor noise added by the measuring circuit, and high-frequency sinusoidal signals that electromagnetically couple from radio broadcasts…