Federal University of Alfenas

Alfenas, Brazil

Time filter

Source Type

Morbec J.M.,Federal University of Alfenas | Rahman G.,Quaid-i-Azam University
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

Using ab initio calculations based on density functional theory, we investigate the effects of vacancies on the electronic and magnetic properties of zigzag SiC nanoribbons (Z-SiCNR). Single (VC and VSi) and double (VSiVSi and VSiVC) vacancies are observed to induce magnetism in Z-SiCNRs. The presence of a single VSi does not affect the half-metallic behavior of pristine Z-SiCNRs; however, a single VC leads to a transition from half-metallic to metallic behavior in Z-SiCNRs due to the edge Si p orbitals and the atoms surrounding the vacancy. The interactions of vacancies with foreign impurity atoms (B and N) are also investigated, and it is observed that V SiNC not only suppresses the oscillatory type magnetism of VSiVC but also retains the half-metallic character of the pristine Z-SiCNRs. The defect formation energies of vacancies can be reduced by substitutional B and N atoms. We believe that ferromagnetism is expected if Z-SiCNRs are grown under suitable conditions. © 2013 American Physical Society.

Damas G.B.,Federal University of Alfenas | Dias A.B.A.,Federal University of Alfenas | Costa L.T.,Federal University of Fluminense
Journal of Physical Chemistry B | Year: 2014

In recent years, the global climate change is in evidence and it is almost a consensus that it is caused by the greenhouse gases emissions. An alternative to reduce these emissions is carbon capture and storage (CCS), which employs solvents based on amine compounds. In this scene, ionic liquids (IL) have been investigated to a greater extent for this application. In this work, we make an evaluation of interactions between gases (CO2, SO2, and H2S) and anion/cation from IL, as well as cation-anion interactions. For this, quantum calculations under vacuum were performed at the B3LYP/6-311+G-* level of theory and using the M06-2X functional, where dispersion effects are considered. Among the well-studied systems based on imidazolium cations and fluorinated anions, we also studied the tetraalkylammonium, tetraalkylphosphonium, ether-functionalized imidazolium based systems, and tetrahexylammonium bis(trifluoromethanesulfonyl)imide, [THA][Tf2N], as a potential prototype. The ion pairs evaluated include [Tf2N]--based IL, with alkyl chain varying from [C1mim]+ to [C8mim]+ and [C 1mim]+-based IL. We found that the anion becomes more available to interact with gas with the weakening of the cation-anion interaction. [THA][Tf2N] has a binding energy of -274.89 kJ/mol at the B3LYP/6-311+G** level of theory, which is considered energetically interesting to gas capture applications. © 2014 American Chemical Society.

Dias K.S.T.,Federal University of Alfenas | Viegas C.,Federal University of Alfenas
Current Neuropharmacology | Year: 2014

Alzheimer’s disease (AD) is a complex neurodegenerative disorder with a multi-faceted pathogenesis. So far, the therapeutic paradigm “one-compound-one-target” has failed and despite enormous efforts to elucidate the pathophysiology of AD, the disease is still incurable. The multiple factors involved in AD include amyloid aggregation to form insoluble neurotoxic plaques of Aβ, hyperphosphorylation of tau protein, oxidative stress, calcium imbalance, mitochondrial dysfunction and deterioration of synaptic transmission. These factors together, accentuate changes in the CNS homeostasis, starting a complex process of interconnected physiological damage, leading to cognitive and memory impairment and neuronal death. A recent approach for the rational design of new drug candidates, also called multitarget-directed ligand (MTDL) approach, has gained increasing attention by many research groups, which have developed a variety of hybrid compounds acting simultaneously on diverse biological targets. This review aims to show some recent advances and examples of the exploitation of MTDL approach in the rational design of novel drug candidate prototypes for the treatment of AD. © 2014 Bentham Science Publishers.

Azevedo L.,Federal University of Alfenas
Journal of medicinal food | Year: 2010

The goal of the this study was to evaluate the mutagenic/antimutagenic effects of conventional (BRS133) and transgenic (BRS 245 RR) soybeans (CS and TS, respectively) in vivo using the bone marrow micronucleus (MN) test, histopathological analysis, chromosome aberration test (CAT), and mitotic index (MI) determination. Six-week-old male Swiss mice were fed with pelleted commercial diet mixed with CS or TS at 10% or 20%. Two experimental designs (MN and CAT) were conducted simultaneously with 10 groups each during a 15-day period. Animals were treated with pelleted commercial diet, CS (10% or 20%), or TS (10% or 20%), and on day 14 they also received cyclophosphamide (CP) (50 mg/kg i.p.). The 10% and 20% CS and TS diets did not significantly decrease the frequencies of micronucleated polychromatic erythrocytes in bone marrow induced by CP. However, the CAT indicated that the 10% and 20% CS diets significantly (P <.05) protected nucleated bone marrow cells against chemical-induced mutagenesis and also produced a significant (P <.05) decrease in the total percentage of spontaneous aberrations. Among the treatments with TS, only the 10% TS diet reduced the percentage of total aberrations induced by CP. The results also indicated that the treatment with 20% TS alone significantly (P <.05) decreased the MI, indicating cytotoxic effects related to the treatment. Taken together, our results suggest that, under the tested conditions, TS and CS have antimutagenic properties and are not toxic.

Vilela F.C.,Federal University of Alfenas | Giusti-Paiva A.,Federal University of Alfenas
Endocrinology | Year: 2011

The influence of glucocorticoids on the neuroendocrine system and behavior of lactating rats is not well known. To evaluate the effects of glucocorticoids on the neuroendocrine system and maternal and aggressive behavior, lactating female rats were treated with dexamethasone or vehicle for 2 h before experiments. Blood samples were collected 15 min after the beginning of suckling to evaluate hormonal changes. To evaluate the maternal behavior of lactating rats, eight pups were placed in their home cages on the side opposite the location of the previous nest, and the resulting behavior of the lactating rat was filmed for 30 min. Aggressive behavior was evaluated by placing a male rat (intruder) in the home cage. Dexamethasone treatment reduced oxytocin and prolactin secretion during lactation and reduced pup weight gain. Relative to control treatment, dexamethasone treatment also adversely affected a variety of maternal behaviors; it increased the latency to build a new nest, decreased the number of pups gathered to the nest, increased the latency to retrieve the first pup, and decreased the percentage of time spent in the arched-nursing position. Dexamethasone treatment, compared with control, also reduced aggressive behavior, as evidenced by an increase in the latency to the first attack, a reduction in the number of front and side attacks, and a decrease in lateral threat and biting. Taken together, our results suggest dexamethasone treatment in lactating rats disrupts prolactin and oxytocin secretion, and this is followed by an attenuation of maternal and aggressive behavior. Copyright © 2011 by The Endocrine Society.

de Carvalho B.C.,Federal University of Alfenas
The International journal of oral & maxillofacial implants | Year: 2013

This 15-year prospective study evaluated the success rate and preservation of the gingival margin of single implants placed in a flapless procedure loaded immediately after extraction or after a healing period. Immediate flapless implant placement was performed in patients who fulfilled specified inclusion criteria. Implants were either immediately restored with a provisional crown or left unloaded (received healing abutment only). Implant success and gingival margin levels were evaluated after implant placement and after 1 to 15 years. A total of 305 healthy nonsmoking subjects (90 men, 215 women) were treated with 430 immediate implants during a 15-year period (December 1994 to December 2009) and monitored for 1 to 15 years. Two hundred seventy-five implants received an immediate provisional crown, and 155 received a healing abutment. The implant survival rate was 93.03% (± 3.74%). The immediate provisional helped to maintain the original gingival margin, although the implant survival rate was higher for implants that were not immediately restored (96.78%) than for the implants that were immediately restored with a provisional (90.9%). This 15-year prospective study showed a favorable implant success rate related to the flapless immediate implant placement protocol with healing abutment placement or an immediate provisional crown to replace a single missing tooth.

Clerici M.T.P.S.,Federal University of Alfenas | Carvalho-Silva L.B.,Federal University of Alfenas
Food Research International | Year: 2011

Brazil is one of the three major fruit producers in the world. Native and/or exotic Brazilian fruits have great nutritional and economic potential. Eggfruit, blackberry, Brazilian guava, atemoya, bacuri, sweetsop, starfruit, feijoa, cactus pear, fruit of wolf, breadfruit, jaboticaba, jackfruit, rose apple, lychee, mangaba and marolo are already present in the Brazilian diet, but they are not yet industrialized and are minor agricultural products. These fruits are produced and used in the manufacture of handicraft products such as jellies and sweets that are available in free markets, but production is small-scale and without safe operational procedures. These fruits are seasonal with large postharvest losses. Thus, it is necessary to initiate competitive agribusinesses in the producing regions for these fruits to enhance local economies. This review summarizes the major nutritional and bioactive compounds found in these fruits, the technological aspects of their cultivation, and future prospects for introducing consumption of these fruits and their respective products to Brazilian and/or foreign markets. © 2011 Elsevier Ltd.

De Faria A.J.,Federal University of Alfenas
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2016

An optical procedure in the context of continuous variables to verify bipartite entanglement without destroying both systems and their entanglement is proposed. To perform the nondestructive verification of entanglement, the method relies on beam-splitter and quantum nondemolition (QND) interactions of the signal modes with two ancillary probe modes. The probe modes are measured by homodyne detections, and the obtained information is used to feed forward modulation of signal modes, concluding the procedure. Characterizing the method by figures of merit used in QND processes, we can establish the conditions for an effectively quantum scheme. Based on such conditions, it is shown that the classical information acquired from the homodyne detections of probe modes is sufficient to verify the entanglement of the output signal modes. The processing impact due to added noise on the output entanglement is assessed in the case of Gaussian modes. © 2016 American Physical Society.

Vilela F.C.,Federal University of Alfenas | Giusti-Paiva A.,Federal University of Alfenas
Behavioural Brain Research | Year: 2014

It has been shown that the endocannabinoid system is involved in the neurohypophyseal hormone secretion produced by exposure to several different stimuli; however, the influence of this system on neuroendocrine responses during lactation is unclear. Therefore, the aim of our study was to investigate the influence of an acute peripheral administration of WIN55,212-2 (cannabinoid receptor agonist) on behavioral and neuroendocrine responses during lactation. On day 6 of lactation, female rats were treated with vehicle or WIN55,212-2 30. min before the start of our experiments. To evaluate maternal behavior, the pups were returned to their home cages to the side of the cage opposite the previous nest, and the resulting behavior of the lactating rats was recorded for the next 30. min. Aggressive behavior was evaluated for 10. min following the placement of an intruder male rat in the home cage. The plasma level of oxytocin and the amount of milk consumption by the pups were evaluated 15. min after the onset of suckling. In addition, double-labelled c-Fos/oxytocin neurons in the medial magnocellular subdivision of the paraventricular nucleus and in the supraoptic nucleus were quantified for each lactating rat. The results show that WIN decreased maternal care, decreased aggressive behaviors, suppressed maternal anxiolysis, decreased plasma oxytocin levels and milk consumption by pups and decreased activation of oxytocinergic neurons in hypothalamic nuclei. Our results indicate that the changes in the behavioral responses of lactating rats treated with WIN maybe can be related to disruption in the neuroendocrine control of oxytocin secretion. © 2014 Elsevier B.V.

Ribeiro-Junior N.V.,Federal University of Alfenas
The International journal of periodontics & restorative dentistry | Year: 2013

Excessive gingival display during smiling ("gummy smile") is an esthetic issue that affects a considerable part of the population. The hyperactivity of the elevator muscle of the upper lip is one of the main causes of a gummy smile, and several techniques have been proposed for its treatment. The aim of this report is to describe a modification of the lip repositioning technique to achieve stable and significant outcomes through a more conservative procedure. Two patients complaining about a gummy smile were treated with the proposed technique and presented, after a 6-month follow-up, significant improvement in the amount of gingival exposure and esthetic satisfaction.

Loading Federal University of Alfenas collaborators
Loading Federal University of Alfenas collaborators