276 research outputs found
Band-gap Shift In Cds Semiconductor By Photoacoustic Spectroscopy: Evidence Of A Cubic To Hexagonal Lattice Transition
The band-gap energies of the CdS semiconductor are obtained by a photoacoustic spectroscopy (PAS) technique over a range of temperature of thermal annealing (TTA), in which the evolution of the sample structure is characterized by x-ray diffraction patterns. The PAS experiment gives a set of data for the band-gap shift in the region of the fundamental absorption edge. With increasing TTA the band-gap shift increases up to a critical TTA when its slope decreases in a roughly symmetrical way. It is suggested that at this temperature a cubic to hexagonal-lattice transition occurs.64329129
Mechanistic Framework for the Formation of Different Sulfur Species by Electron Irradiation of n-Dodecanethiol Self-Assembled Monolayers on Au(111) and Au(100)
The electron-induced damage in self-assembled monolayers (SAMs) of n-dodecanethiolate on Au(111) and Au(100) single-crystalline surfaces is investigated in situ by X-ray photoelectron spectroscopy. The same irradiation dose produced different adsorbed groups. The damage at the headgroupâsubstrate interface leads to find dialkyl sulfide (RSâRâČ) on Au(111), while dialkyl disulfide (RSâSR) and/or thiol (RSH) were produced on Au(100). With regard to C species, significant amounts of CâC are generated on Au(111) but not on Au(100), showing that double bond formation is not triggered through the same pathways on these surfaces. Detailed analysis of a variety of mechanisms, which involved cationic (RS+), anionic (RSâ), or thiyl radical (RSâą) species, in combination with ab initio density functional theory (DFT) calculation, leads to the conclusion that the radical pathways successfully explain the experimental results. Molecular dynamics simulations show that the n-dodecanethiolate SAMs on both surfaces are equivalent with regard to the van der Waals interactions. The breakage of the SâAu bonds is studied by means of DFT calculations. The thiyl radical would form close to the Au(100) surface, making it likely to react with another thiyl radical or thiolate to form the RSâSR species. On the other hand, for Au(111), the thiyl radical would form farther from the surface, reacting with the alkyl chains of neighboring molecules to form RSâRâČ species. The mechanistic framework proposed here is very useful to explain the behavior of related systems.This work was supported in part by CONICET (PIP 0333), ANPCyT (PICT 2017-4519), Universidad Nacional de La Plata (UNLP X786) of Argentina, and Universidad Nacional de Cuyo. J.O.-A. and M.M.M. acknowledge financial support from CONICET through Grant PIP 11220150100141CO, FONCyT PICT-2015-2191, and SeCyT UNC. This work has used computational resources from CCAD, Universidad Nacional de CoÌrdoba (http://ccad.unc.edu.ar/) and resources provided by the CYTED co-funded Thematic Network RICAP (517RT0529)
Caso clĂnico: bacteriemia por Erysipelothrix rhusiopathiae
Erysipelothrix rhusiopatiae es una bacteria comensal y patógena de animales, especialmente cerdos. En humanos, puede aparecer en forma de lesiones cutåneas llamada erisipeloide, es infrecuente la bacteriemia asociada o no a compromiso cutåneo. En América Latina se han comunicado solo 5 casos de bacteriemia por esta especie.Facultad de Ciencias Veterinaria
Caso clĂnico: bacteriemia por Erysipelothrix rhusiopathiae
Erysipelothrix rhusiopatiae es una bacteria comensal y patógena de animales, especialmente cerdos. En humanos, puede aparecer en forma de lesiones cutåneas llamada erisipeloide, es infrecuente la bacteriemia asociada o no a compromiso cutåneo. En América Latina se han comunicado solo 5 casos de bacteriemia por esta especie.Facultad de Ciencias Veterinaria
Caso clĂnico: bacteriemia por <i>Erysipelothrix rhusiopathiae</i>
Erysipelothrix rhusiopatiae es una bacteria comensal y patógena de animales, especialmente cerdos. En humanos, puede aparecer en forma de lesiones cutåneas llamada erisipeloide, es infrecuente la bacteriemia asociada o no a compromiso cutåneo. En América Latina se han comunicado solo 5 casos de bacteriemia por esta especie.Facultad de Ciencias Veterinaria
Comparison of three microsatellite analysis methods for detecting genetic diversity in Phytophthora sojae (Stramenopila: Oomycete)
Analysis of an organismâs genetic diversity requires a method that gives reliable, reproducible results. Microsatellites are robust markers, however, detection of allele sizes can be difficult with some systems as well as consistency among laboratories. In this study, our two laboratories used 219 isolates of Phytophthora sojae to compare three microsatellite methods. Two capillary electrophoresis methods, the Applied Biosystems 3730 Genetic Analyzer and the CEQ 8000 Genetic Analysis system, detected an average of 2.4-fold more alleles compared to gel electrophoresis with a mean of 8.8 and 3.6 alleles per locus using capillary and gel methods, respectively. The two capillary methods were comparable, although allele sizes differed consistently by an average of 3.2Â bp across isolates. Differences between capillary methods could be overcome if reference standard DNA genotypes are shared between collaborating laboratories
Stand-alone tsunami alarm equipment
One of the quickest means of tsunami evacuation is transfer to
higher ground soon after strong and long ground shaking. Ground shaking
itself is a good initiator of the evacuation from disastrous tsunami. Longer period seismic waves are considered to be more correlated with the
earthquake magnitude. We investigated the possible application of this to
tsunami hazard alarm using single-site ground motion observation. Information
from the mass media is sometimes unavailable due to power failure soon after
a large earthquake. Even when an official alarm is available, multiple
information sources of tsunami alert would help people become aware of the coming
risk of a tsunami. Thus, a device that indicates risk of a tsunami without requiring other data would be helpful to those who should evacuate. Since
the sensitivity of a low-cost MEMS (microelectromechanical systems)
accelerometer is sufficient for this purpose, tsunami alarm equipment for
home use may be easily realized. Amplitude of long-period (20âŻs cutoff)
displacement was proposed as the threshold for the alarm based on empirical
relationships among magnitude, tsunami height, hypocentral distance, and peak
ground displacement of seismic waves. Application of this method to recent
major earthquakes indicated that such equipment could effectively alert
people to the possibility of tsunami
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