Rio de Janeiro, Brazil

Federal University of Fluminense
Rio de Janeiro, Brazil

The Fluminense Federal University is one of the four federally funded public universities in the State of Rio de Janeiro, Brazil. The university was established by federal law on December 18, 1960. It is the union of five federal colleges and three state colleges. It has about 50,000 undergraduate students, and 12,000 graduate students . It has six campuses in the city of Niterói, on the southeast side of Guanabara Bay, and 12 satellite campuses in towns of the state. There are 68 undergraduate and 208 graduate programs available at UFF in Natural and Social science.The word fluminense in Portuguese, from Latin flumen , is the native adjective for the state of Rio de Janeiro.The Law School of Fluminense Federal University was founded in 1912. The School of Medicine of Fluminense Federal University is one of the Brazilian leading schools in scientific research and article publications.UFF holds the first undergraduate course in Film ever created in Brazil, founded by Nelson Pereira dos Santos. Wikipedia.

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Mattos L.V.,Federal University of Fluminense | Jacobs G.,University of Kentucky | Davis B.H.,University of Kentucky | Noronha F.B.,Brazilian National Institute of Technology
Chemical Reviews | Year: 2012

Significant progress has been made in gaining insight into the reaction mechanisms of ethanol reforming. To this end, infrared spectroscopy has been a powerful tool in achieving this goal. The dissociation of ethanol to ethoxy species can occur on the support, and those with sufficiently labile O adatoms or OH groups offer a means of accomplishing this step. Dehydrogenation of the ethoxy species to acetaldehyde is very likely assisted by the metal particles added to the support, as well as the presence of labile O adatoms or hydroxyl groups located on the support. A major route to catalyst deactivation is that of carbon formation. Temperature-programmed oxidation, used to characterize the nature of carbon deposits, demonstrated significant amounts of carbon deposited on the catalyst surface. The metal appears to operate across the metal-oxide junction to assist in hydrogen transfer and related reactions such as acetate demethanation.

Rakov N.,Federal University of Vale do São Francisco | Maciel G.S.,Federal University of Fluminense
Optics Letters | Year: 2014

Er3+ doped powders are generally used for fluorescence-based temperature sensing application when near-infrared lasers are the excitation sources of choice. The fluorescence of Er3+ is produced by nonlinear (upconversion) processes, which generate strong internal heat. Lowering the excitation power causes drastic reduction of the fluorescence signal, and as a consequence the sensor applicability of Er3+ doped powders becomes compromised. Here we propose the use of the downconverted fluorescence of Yb3+ produced by efficient energy transfer from Nd3+ as an alternative temperature sensing system. Our results are presented for yttrium silicate powders prepared by combustion synthesis. © 2014 Optical Society of America.

Reis M.S.,Federal University of Fluminense
Applied Physics Letters | Year: 2011

This Letter presents the oscillatory behavior found in the magnetic entropy change of diamagnetic materials. We show that this quantity depends on the oscillating term and, as a consequence, the magnetocaloric potential can be tuned as either inverse or normal, depending on the value of the magnetic field change. A quite small change (≈10-3 T) of the magnetic field change is able to invert the magnetic entropy change. These results open doors for applications at quite low temperatures and can be further developed to be incorporated into adiabatic demagnetization refrigerators, as well as sensible magnetic field sensors. © 2011 American Institute of Physics.

Soares R.L.S.,Federal University of Fluminense
World Journal of Gastroenterology | Year: 2014

Irritable bowel syndrome (IBS) remains a clinical challenge in the 21st century. It's the most commonly diagnosed gastrointestinal condition and also the most common reason for referral to gastroenterology clinics. Its can affect up to one in five people at some point in their lives, and has a significantly impact of life quality and health care utilization. The prevalence varies according to country and criteria used to define IBS. Various mechanisms and theories have been proposed about its etiology, but the biopsychosocial model is the most currently accepted for IBS. The complex of symptoms would be the result of the interaction between psychological, behavioral, psychosocial and environmental factors. The diagnosis of IBS is not confirmed by a specific test or structural abnormality. It is made using criteria based on clinical symptoms such as Rome criteria, unless the symptoms are thought to be atypical. Today the Rome Criteria III is the current goldstandard for the diagnoses of IBS. Secure positive evidence of IBS by means of specific disease marker is currently not possible and cannot be currently recommended for routine diagnosis. There is still no clinical evidence to recommend the use of biomarkers in blood to diagnose IBS. However, a number of different changes in IBS patients were demonstrated in recent years, some of which can be used in the future as a diagnostic support. IBS has no definitive treatment but could be controlled by non-pharmacologic management eliminating of some exacerbating factors such certain drugs, stressor conditions and changes in dietary habits. The traditional pharmacologic management of IBS has been symptom based and several drugs have been used. However, the cornerstone of its therapy is a solid patient physician relationship. This review will provide a summary of pathophysiology, diagnostic criteria and current and emerging therapies for IBS. © 2014 Baishideng Publishing Group Inc. All rights reserved.

Reis M.S.,Federal University of Fluminense
Applied Physics Letters | Year: 2012

The magnetocaloric effect of non-relativistic diamagnetic materials presents an oscillatory character due to the crossing of the Landau levels with the Fermi energy. This effect occurs at low temperature (ca 1 K) and high magnetic field (ca 10 T). Considering the relativistic properties of graphenes, a 2D massless diamagnetic material, these oscillations could be preserved and the effect occurs in a much higher temperature (ca 100 K), due to the huge Fermi velocity (106 m/s). In addition, the magnetocaloric effect can be tuned as either inverse or normal, by changing the magnetic field change in ca 3.4 T. © 2012 American Institute of Physics.

Reis M.S.,Federal University of Fluminense
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2014

The present Letter describes the magnetocaloric effect of a diamagnetic material with a magnetic field B∥ along the z axis and a transversal and oscillating field B⊥(≪B∥) parallel to the x-y plane. We show that the magnetocaloric potentials due to a change in B∥ are the same as those due to a change in the frequency of B⊥. These results raise the possibility of building magnetocaloric devices without moving parts, since changing frequency is a simple electronic issue, while changing the field from permanent magnets depends on mechanical aspects. © 2014 Elsevier B.V.

Rulli C.C.,Federal University of Fluminense | Sarandy M.S.,Federal University of Fluminense
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

We propose a global measure for quantum correlations in multipartite systems, which is obtained by suitably recasting the quantum discord in terms of relative entropy and local von Neumann measurements. The measure is symmetric with respect to subsystem exchange and is shown to be nonnegative for an arbitrary state. As an illustration, we consider tripartite correlations in the Werner-GHZ (Greenberger-Horne-Zeilinger) state and multipartite correlations at quantum criticality. In particular, in contrast with the pairwise quantum discord, we show that the global quantum discord is able to characterize the infinite-order quantum phase transition in the Ashkin-Teller spin chain. © 2011 American Physical Society.

Reis M.S.,Federal University of Fluminense
Solid State Communications | Year: 2012

The fundamental model to describe a diamagnetic material is an electron gas; and a huge applied magnetic field promotes a degeneracy, named Landau levels. Oscillations on the thermodynamic quantities are found when the Landau levels cross the Fermi energy of the non-perturbed gas at low temperatures regime ( εFkBT). The adiabatic temperature change ΔT characterizes the magnetocaloric properties and here this quantity is described for the system above mentioned. We show that ΔT oscillations are possible to be found in Gold in standard values of temperature and magnetic field; c.a.2 K and 8.5 T. These oscillations are around zero, i.e., both, normal and inverse magnetocaloric effect arises and a possible application of this effect is in magnetic field sensor, since this system is sensible to 0.8 mT with a thermal response of 50 mK (at 2.56 K). © 2012 Elsevier Ltd. All rights reserved.

Reis M.S.,Federal University of Fluminense
Solid State Communications | Year: 2013

The present effort explores the influence of a longitudinal applied electric field on the magnetocaloric properties of graphenes. The magnetic entropy change ΔS(T,ΔB,E) has two contributions: Scos(T,B,E) with an oscillating character on m, inversely proportional to the magnetic field; and Sper(T,B,E) with a periodic character also on m. In comparison to the case without electric field, the maximum value of the magnetic entropy change either increases or decreases due to an applied electric field, depending on the value of m; and, in addition, the temperature in which the maximum entropy change occurs decreases due to the electric field. © 2013 Elsevier Ltd. All rights reserved.

Goutorbe B.,Federal University of Fluminense
Earth and Planetary Science Letters | Year: 2010

The thermal structure and evolution of the oceanic lithosphere is revisited with the help of a global shear velocity model of the upper mantle. Seismic velocities of the lithospheric mantle are converted to temperatures, with a particular care dedicated to the estimation of final uncertainties. These are evaluated from a Monte Carlo error propagation, taking into account the uncertainties on velocities and those on the parameters related to the velocity-temperature relationship (mantle composition, thermoelastic properties and attenuation factor). The seismically derived temperature, averaged by age interval, serves to constrain the thermal structure of the lithosphere, together with surface heat flow and ocean depth. Using an experimentally determined thermal expansivity α, the Chablis model, which prescribes a constant heat flow at some isotherms, provides a much better fit to all data than the plate model, which imposes a constant basal temperature. Only a strongly reduced α (30% reduction) allows the latter model to achieve a joint fitting comparable to the Chablis model, and then with a fit to seismically derived temperature that remains inferior the latter model. The good fit of the plate model thus depends on a reduction of α down to the lower possible limit and relies mostly on ocean depth, whose behavior at old ages is considerably obscured by anomalous crust. The Chablis model therefore appears favored by this study, which should give new perspectives on various processes related to mantle convection and to the dynamics of the lithosphere. © 2010 Elsevier B.V.

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