5,422 research outputs found
Core excitation in Ozone localized to one of two symmetry-equivalent chemical bonds - molecular alignment through vibronic coupling
Core excitation from terminal oxygen O in O is shown to be an
excitation from a localized core orbital to a localized valence orbital. The
valence orbital is localized to one of the two equivalent chemical bonds. We
experimentally demonstrate this with the Auger Doppler effect which is
observable when O is core-excited to the highly dissociative
O1s7a state. Auger electrons emitted from the atomic oxygen
fragment carry information about the molecular orientation relative to the
electromagnetic field vector at the moment of excitation. The data together
with analytical functions for the electron-peak profiles give clear evidence
that the preferred molecular orientation for excitation only depends on the
orientation of one bond, not on the total molecular orientation. The
localization of the valence orbital "7a" is caused by mixing of the valence
orbital "5b" through vibronic coupling of anti-symmetric stretching mode
with b-symmetry. To the best of our knowledge, it is the first discussion
of the localization of a core excitation of O. This result explains the
success of the widely used assumption of localized core excitation in
adsorbates and large molecules
Granular cooling of hard needles
We have developed a kinetic theory of hard needles undergoing binary
collisions with loss of energy due to normal and tangential restitution. In
addition, we have simulated many particle systems of granular hard needles. The
theory, based on the assumption of a homogeneous cooling state, predicts that
granular cooling of the needles proceeds in two stages: An exponential decay of
the initial configuration to a state where translational and rotational
energies take on a time independent ratio (not necessarily unity), followed by
an algebraic decay of the total kinetic energy . The simulations
support the theory very well for low and moderate densities. For higher
densities, we have observed the onset of the formation of clusters and shear
bands.Comment: 7 pages, 8 figures; major changes, extended versio
The pasta phase within density dependent hadronic models
In the present paper we investigate the onset of the pasta phase with
different parametrisations of the density dependent hadronic model and compare
the results with one of the usual parametrisation of the non-linear Walecka
model. The influence of the scalar-isovector virtual delta meson is shown. At
zero temperature two different methods are used, one based on coexistent phases
and the other on the Thomas-Fermi approximation. At finite temperature only the
coexistence phases method is used. npe matter with fixed proton fractions and
in beta-equilibrium are studied. We compare our results with restrictions
imposed on the the values of the density and pressure at the inner edge of the
crust, obtained from observations of the Vela pulsar and recent isospin
diffusion data from heavy-ion reactions, and with predictions from spinodal
calculations.Comment: 15 pages, 11 figures and 7 table
Índice de sobrevivência de portaenxertos de citros enxertados com pomeleiro sob estresse salino.
Altas concentrações de sais no solo tendem a promover redução no crescimento e na produção das maiorias das plantas cultivadas, fato que é observado, principalmente em regiões áridas e semi-áridas, pois, normalmente, há condição de balanço hídrico negativo, ou seja, a evapotranspiração ocorrente durante o ano é maior que a precipitação, verificando-se a evaporação da água e acumulo de sais na superfície (AYERS e WESTCOT, 1999; TESTER e DAVENPORT, 2003). Para Richards (1954), os sais podem afetar o desenvolvimento das plantas devido à sua concentração na solução do solo, diminuindo o potencial osmótico e reduzindo a disponibilidade de água para os vegetais; pode haver, também, o efeito tóxico de íons específicos, como sódio, cloreto e boro, dentre outros que causam sintomas característicos de injúria (FLOWERS e FLOWERS, 2005). Porém algumas culturas produzem rendimentos economicamente viáveis em níveis altos de salinidade no solo, enquanto outras são sensíveis em níveis relativamente baixos; diferença relacionada à maior capacidade de adaptação osmótica que algumas espécies possuem (AYERS e WESTCOT, 1999). Tal fato é muito útil para seleção de genótipos mais tolerantes quando não se pode manter a salinidade do solo em níveis baixos (TESTER e DAVENPORT, 2003).pdf 230
Tiling the plane without supersymmetry
We present a way of tiling the plane with a regular hexagonal network of
defects. The network is stable and follows in consequence of the
three-junctions that appear in a model of two real scalar fields that presents
symmetry. The symmetry is effective in both the vacuum and defect
sectors, and no supersymmetry is required to build the network.Comment: Revtex, 4 pages, 1 ps figure; version to appear in Phys. Rev. Let
Zoneamento climático da ferrugem do eucalipto para o Estado do Paraná.
Edição do 37º Congresso Paulista de Fitopatologia. CD-ROM. Resumo 140
Vortex Glass and Vortex Liquid in Oscillatory Media
We study the disordered, multi-spiral solutions of two-dimensional
homogeneous oscillatory media for parameter values at which the single
spiral/vortex solution is fully stable. In the framework of the complex
Ginzburg-Landau (CGLE) equation, we show that these states, heretofore believed
to be static, actually evolve on ultra-slow timescales. This is achieved via a
reduction of the CGLE to the evolution of the sole vortex position and phase
coordinates. This true defect-mediated turbulence occurs in two distinct
phases, a vortex liquid characterized by normal diffusion of individual
spirals, and a slowly relaxing, intermittent, ``vortex glass''.Comment: 4 pages, 2 figures, submitted to Physical Review Letter
AMLODIPINE BESYLATE LOADED POLYMERIC NANOPARTICLES: PREPARATION AND IN VITRO CHARACTERISATION
Objective: The present investigation aims to formulate the ideal drug formulation using different surfactants and optimize the amlodipine-loaded polymeric nanoparticles.
Methods: The present work was to formulate the drug-loaded polymeric nanoparticles to enhance the dissolution rate of a poorly water-soluble drug, amlodipine besylate, using the anti-solvent precipitation method. The Characterisation studies include particle size (nm), Zeta potential (mV), polydispersity index, Drug entrapment efficiency (%), in vitro release drug release, and surface morphological studies like SEM and XRD.
Results: The drug-loaded Polymeric nanoparticles of F3 containing PLGA and PVA shows the desired smaller particle size is 198.8±5.25, maximum zeta potential is-24.76±2.54 mv and the stable polydispersity index of 0.957±0.45. The drug entrapment efficiency is 93%, and the controlled dissolution of the ideal formulation pattern is about 94.88±2.45 in 24h.
Conclusion: The release pattern observed that PNs significantly improved the dissolution character of amlodipine besylate. PNs have a controlled drug release pattern and can be used as a suitable drug delivery carrier for low solubility and poorly bioavailable drugs like amlodipine to improve its dissolution rate
Efeitos de gramíneas forrageiras sobre a porosidade do solo em Uruará (Transamazônica), Pará.
Cópia de CD-ROM
Muons enhancements at sea level in association with Swift-BAT and MILAGRO triggers
Recently, triggers occurring during high background rate intervals have been
reporter by Swift-BAT Gamma Ray Burst (GRB) detector. Among them, there were
two on January 24, two on January 25, and two on February 13, and 18, all in
2008. These Swift-BAT triggers in most cases are probably noise triggers that
occurred while Swift was entering the South Atlantic Anomaly (SAA). In fact, we
show that they happen during a plentiful precipitation of high energy particles
in the SAA, producing muons in the atmosphere detected by two directional
telescopes at sea level, inside the SAA region (Tupi experiment). They look
like sharp peaks in the muon counting rate. In the same category are two
triggers from MILAGRO ground based detector, on January 25 and 31, 2008
respectively. In addition, the trigger coordinates are close to (and, in two
cases, inside) the field of view of the telescopes. From an additional analysis
in the behavior of the muon counting rate, it is possible to conclude that the
events are produced by precipitation of high energy charged particles in the
SAA region. Thus, due to its localization, the Tupi experiment constitutes a
new sensor of high energy particle precipitation in the SAA, and it can be
useful in the identification of some triggers of Gamma Ray Burst detectors.Comment: 7pages, 5 figure
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