Confined systems through variational supersymmetric quantum mechanics

The energy states of the confined harmonic oscillator and the Hulthén potentials are evaluated using the Variational Method associated to Supersymmetric Quantum Mechanics.

State Dependent Riccati Equation (SDRE) control method applied in cancellation of a parametric resonance in a magnetically levitated body

Here, a simplified dynamical model of a magnetically levitated body is considered. The origin of an inertial Cartesian reference frame is set at the pivot point of the pendulum on the levitated body in its static equilibrium state (ie, the gap between the magnet on the base and the magnet on the body, in this state). The governing equations of motion has been derived and the characteristic feature of the strategy is the exploitation of the nonlinear effect of the inertial force associated, with the motion of a pendulum-type vibration absorber driven, by an appropriate control torque [4]. In the present paper, we analyzed the nonlinear dynamics of problem, discussed the energy transfer between the main system and the pendulum in time, and developed State Dependent Riccati Equation (SDRE) control design to reducing the unstable oscillatory movement of the magnetically levitated body to a stable fixed point. The simulations results showed the effectiveness of the (SDRE) control design. Copyright © 2011 by ASME.

Magnetothermal instabilities in magnetized anisotropic plasmas

Using the 16-moment transport equations for an ideal anisotropic collisionless plasma we analyze the influence of pressure anisotropy on the magnetothermal (MTI) and heat-flux-driven buoyancy (HBI) instabilities. We calculate the dispersion relation and the growth rates for these instabilities in the presence of a background heat flux and for configurations with static pressure anisotropy, finding that when the frequency at which heat conduction acts is much larger than any other frequency in the system (i.e. weak magnetic field) the pressure anisotropy has no effect on the MTI/HBI, provided the degree of anisotropy is small. In contrast, when this ordering of timescales does not apply the instability criteria depend on pressure anisotropy.

Elucidating capacitance and resistance terms in confined electroactive molecular layers

Electrochemical analyses on confined electroactive molecular layers, herein exemplified with electroactive self-assembled monolayers, sample current contributions that are significantly influenced by additional nonfaradaic and uncompensated resistance effects that, though unresolved, can strongly distort redox analysis. Prior work has shown that impedance-derived capacitance spectroscopy approaches can cleanly resolve all contributions generated at such films, including those which are related to the layer dipolar/electrostatic relaxation characteristics. We show herein that, in isolating the faradaic and nonfaradaic contributions present within an improved equivalent circuit description of such interfaces, it is possible to accurately simulate subsequently observed cyclic voltammograms (that is, generated current versus potential patterns map accurately onto frequency domain measurements). Not only does this enable a frequency-resolved quantification of all components present, and in so doing, a full validation of the equivalent circuit model utilized, but also facilitates the generation of background subtracted cyclic voltammograms remarkably free from all but faradaic contributions. © 2012 American Chemical Society.

Utilização de plasmas em pressão atmosférica para modificação de polímeros biocompatíveis

Pós-graduação em Ciência e Tecnologia de Materiais - FC

Efeito da implantação iônica por imersão em plasmas sobre a bioatividade de titânio

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

TENSILE AND CREEP BEHAVIOR OF GEOSYNTHETICS USING CONFINED-ACCELERATED TESTS

A major aspect in geosynthetics creep analysis is the load level applied to the specimen, usually referred as a percentage of the geosynthetic ultimate tensile strength (UTS). Since both tensile and creep standard tests are performed with in-isolation specimens, they may not reproduce the possibly significant effect of soil-geosynthetic interaction. A new creep testing machine was recently developed and successfully addressed this concern. However, further developments allowed tensile tests to be performed in the same conditions used in nonconventional creep ones. This paper presents the results of nonconventional tensile tests performed with a woven biaxial polyester geogrid. They were used to define its UTS in the same conditions employed in creep tests performed with the new equipment. Despite changes in tensile curves shapes were found, the UTS from confined, accelerated and confined-accelerated tensile tests were quite similar to those obtained with standard tensile test procedure.

A magnetically drivable nanovehicle for curcumin with antioxidant capacity and MRI relaxation properties

Curcumin possesses wide-ranging anti-inflammatory and anti-cancer properties and its biological activity can be linked to its potent antioxidant capacity. Superparamagnetic maghemite (gamma-Fe2O3), called surface-active maghemite nanoparticles (SAMNs) were surface-modified with curcumin molecules, due to the presence of under-coordinated Fe-III atoms on the nanoparticle surface. The so-obtained curcumin-modified SAMNs (SAMN@curcumin) had a mean size of 13 +/- 4 nm. SAMN@curcumin was characterized by transmission and scanning electron microscopy, UV/Vis, FTIR, and Mossbauer spectroscopy, X-ray powder diffraction, bulk susceptibility (SQUID), and relaxometry measurements (MRI imaging). The high negative contrast proclivity of SAMN@curcumin to act as potential contrast agent in MRI screenings was also tested. Moreover, the redox properties of bound curcumin were probed by electrochemistry. SAMN@curcumin was studied in the presence of different electroactive molecules, namely hydroquinone, NADH and ferrocyanide, to assess its redox behavior. Finally, SAMN@curcumin was electrochemically probed in the presence of hydrogen peroxide, demonstrating the stability and reactivity of bound curcumin.

Lysine in the diet of Rhamdia voulezi male broodstocks confined in net cages

The focus of this study was to evaluate the effect of lysine on the productive (weight and length gain, apparent feed conversion, specific growth rate and condition factor) and reproductive performance of Rhamdia voulezi males confined in net cages during the first reproductive cycle. The following parameters were assessed: seminal parameters (motility rate and duration, survival, sperm concentration, morphology, pH and osmolarity), hormonal parameters (cortisol and testosterone), testicular tissue (histomorphology), organosomatic indices (gonadosomatic, hepatosomatic and viscerosomatic indices) and composition of essential amino acids, crude protein and moisture of whole carcass. Four hundred fish were used, distributed in a random experimental design with four treatments and four replications in 16 net cages with 25 fish each. The treatments consisted of four different diets prepared so as to contain the following levels of lysine: 1.20, 1.40, 1.60 and 1.80%, with 30% crude protein and 3500 kcal kg(-1) digestible energy for 185 days (Jul./12-Jan./13). Eighteen males were selected per treatment, and they all released semen after slight abdominal pressure. The males were weighed, measured, submitted to hypophysation (2.5 mg kg(-1) carp pituitary extract), and then had their semen and blood collected. The fish were sacrificed by cervical dislocation, dissected, and the testes, liver, fat and guts were removed and weighed. The effects (p < 0.05) for the means of final weight, weight gain, apparent feed conversion and condition factor were observed for the analysis of productive performance. With regard to the reproductive parameters, only the seminal volume was affected (p < 0.05). Thus, the levels of testosterone showed quadratic effect (p < 0.05). The anatomy and the histomorphology of the testes were similar between the treatments during the spermiation period. With regard to the organosomatic indices, there was no influence (p > 0.05) between the treatments. The amino acids in the carcass were not affected (p > 0.05). The increment of lysine in the diet provided linear increase for weight gain and seminal volume and linear decrease for feed conversion in R. voulezi broodstocks confined in net cages. (C) 2014 Elsevier B.V. All rights reserved.

Caracterização de plasmas através da espectrometria de massa

Mass spectrometry is a diagnosis that can aid in the understanding of the kinetics of chemical plasma environment. Through this you can get information about some species present in the environment and make inferences about the behavior of the plasma when parameters such as pressure and applied power changes. When analyzed plasmas generated by the discharge of argon and diglyme (both individually and mixtures of them in various proportions) could be found conditions in which the plasma behavior was different from what is often found in the literature. By the end some peculiar characteristics of plasmas generated by mixing argon / diglyme were raised and it was found that the noble gas is a good mediator of physical and chemical reactions that occur in the environment, and help in the understanding of chemical kinetics. Therefore mass spectrometry was shown highly important tool for the study of plasma environment

Caracterização de plasmas a partir do monômero digime através da espectrometria de massa: deposição polimérica

Pós-graduação em Engenharia Mecânica - FEG

Avaliação das características de superfície e formação de biofilmes em materiais odontológicos tratados em plasmas de HMDSO

Pós-graduação em Reabilitação Oral - FOAR

Lipid sources with different fatty acid profile alters the fatty acid profile and quality of beef from confined nellore steers

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Magnetically drivable nano-bio-conjugate mimicking free curcumin redox behavior

Curcumin possesses wide-ranging anti-inflammatory and anti-cancer properties and its biological activity can be correlated to its potent antioxidant capacity. Novel maghemite (gamma-Fe3O4) nanoparticles, characterized by a diameter of about 10 nm and possessing peculiar colloidal properties and surface interactions, called Surface Active Maghemite Nanoparticles (SAMN), were superficially modified with curcumin by simple incubation, due to the presence of under-coordinated Fe(III) atoms on nanoparticle surface. The resulting curcumin-modified SAMNs (SAMN@curcumin) were characterized by transmission electron microscopy (TEM), FTIR, Mossbauer, EPR and UV-Vis spectroscopy. The redox properties of bound curcumin were tested by electrochemistry. Finally, SAMN@curcumin was studied in the presence of different electroactive substances, namely hydroquinone, NADH and ferrocyanide, in order to assess its electrochemical behavior. Moreover, SAMN@curcumin was electrochemically tested in the presence of one of the most diffuse reactive oxygen specie, such as hydrogen peroxide, demonstrating its stability. SAMN@curcumin in which curcumin is firmly bound, but still retaining its redox features represents a feasible adduct: a magnetically drivable nano-bio-conjugate mimicking free Curcumin redox behavior. The proposed nanostructured material could be exploited as magnetic drivable curcumin vehicle for biomedical applications.

Influence of the Hall effect on convection in plasmas

The influence of the Hall effect on stationary convection in shearless current-carrying plasma columns is considered. It is shown that the Hall effect can inhibit the formation of convection cells generated by viscosity and resistivity.