Effect of seating forces on cement-ceramic adhesion in microtensile bond tests

Objectives: The aim of this study was to evaluate the effect of different seating forces during cementation in cement-ceramic microtensile bond strength (μTBS). Materials and methods: Forty-five blocks (5 × 5 × 4 mm3) of a glass-infiltrated alumina-based ceramic (In-Ceram Alumina) were fabricated according to the manufacturer's instructions and duplicated in resin composite. Ceramic surfaces were polished, cleaned for 10 min in an ultrasonic bath, silica coated using a laboratory type of air abrasion device, and silanized. Each treated ceramic block was then randomly assigned to five groups (n = 9) and cemented to a composite block under five seating forces (10 g, 50 g, 100 g, 500 g, and 750 g) using a dual-cured resin cement (Panavia F). The ceramic-cement-composite assemblies were cut under coolant water to obtain bar specimens (1 mm × 0. 8 mm2). The μTBS tests were performed in a universal testing machine (1 mm/min). The mean bond strengths values were statistically analyzed using one-way ANOVA (α ≤ 0. 05). Results: Different seating forces resulted in no significant difference in the μTBS results ranging between 13. 1 ± 4. 7 and 18. 8 ± 2. 1 MPa (p = 0. 13) and no significant differences among cement thickness. Conclusions: Excessive seating forces during cementation seem not to affect the μTBS results. Clinical relevance: Excessive forces during the seating of single all-ceramic restorations cementation seem to display the same tensile bond strength to the resin cement. © 2012 Springer-Verlag.

A simple derivation of the Lindblad equation

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Efeitos do tratamento com formalina e sulfato de cobre sobre os parâmetros hematológicos e parasitos monogenéticos em juvenis de Hemigrammus sp. (Osteichthyes: Characidae)

The objective of this study was to evaluate the effectiveness of formalin and copper sulphate to control monogeneans in juvenile Hemigrammus sp and its effect on leukocyte count. We used a completely randomized design with five treatments and three replications. All treatments lasted for three days and consisted of: T1, control; T2 and T3 immersion bath for one hour in formalin, an of two concentrations of 0.25 ml formalin and the other 0.1 ml L-1; the T4 bath for 24 hours with 0,025 ml of formalin-L-1; and T5, bath 24 hours with copper sulphate (0.3 mg L-1). After the experimental period was observed that T2, 100% mortality. The T3 and T5 provided 100% efficiency, however, fish presented mortalities and intoxication of the 66 and 80% respectively. T4 showed an efficacy of 77.7% and decrease in parasitological indices: total number of parasites of11, 3 ± 9, mean infection intensity of 3.2 ± 2 and a prevalence of 47.1%. As the leukocytes was observed that at T3, T4 and T5 occurred differences in the proportion of lymphocytes, monocytes and neutrophils as compared to control. The CuSO4 and formalin reduce the parasite load, but presented to be toxic at higher concentrations.

Slimmer or Fertile? Pharmacological Mechanisms Involved in Reduced Sperm Quality and Fertility in Rats Exposed to the Anorexigen Sibutramine

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

GFAAS determination of mercury in muscle samples of fish from Amazon, Brazil

In the present study, a simple, rapid and sensitive method was developed for the determination of mercury concentrations in the muscle tissue of fish from the Brazilian Amazon using graphite furnace atomic absorption spectrometry (GFAAS) following acid mineralization of the samples in an ultrasonic cold water bath. Using copper nitrate as a chemical modifier in solution and sodium tungstate as permanent modifier, we were able to attain thermal stabilization of the mercury up to the atomisation temperature of 1600 °C in the GFAAS assay. The calculated limits of detection (LOD) and quantification (LOQ) were 0.014 and 0.047 mg kg-1, respectively. © 2013 Elsevier Ltd. All rights reserved.

Effect of diamond-like carbon thin film coated acrylic resin on candida albicans biofilm formation

Purpose: The purpose of this study was to evaluate the effect of diamond-like carbon thin films doped and undoped with silver nanoparticles coating poly(methyl methacrylate) (PMMA) on Candida albicans biofilm formation. The control of biofilm formation is important to prevent oral diseases in denture users. Materials and Methods: Forty-five PMMA disks were obtained, finished, cleaned in an ultrasonic bath, and divided into three groups: Gc, no surface coating (control group); Gdlc, coated with diamond-like carbon film; and Gag, coated with diamond-like carbon film doped with silver nanoparticles. The films were deposited using a reactive magnetron sputtering system (physical vapor deposition process). The specimens were characterized by optical profilometry, atomic force microscopy, and Rutherford backscattering spectroscopy analyses that determined differences in chemical composition and morphological structure. Following sterilization of the specimens by γ-ray irradiation, C. albicans (ATCC 18804) biofilms were formed by immersion in 2 ml of Sabouraud dextrose broth inoculated with a standardized fungal suspension. After 24 hours, the number of colony forming units (cfu) per specimen was counted. Data concerning biofilm formation were analyzed using ANOVA and the Tukey test (p < 0.05). Results: C. albicans biofilm formation was significantly influenced by the films (p < 0.00001), reducing the number of cfu, while not affecting the roughness parameters (p > 0.05). The Tukey test showed no significant difference between Gdlc and Gag. Films deposited were extremely thin (∼50 nm). The silver particles presented a diameter between 60 and 120 nm and regular distribution throughout the film surface (to Gag). Conclusion: Diamond-like carbon films, doped or undoped with silver nanoparticles, coating the base of PMMA-based dentures could be an alternative procedure for preventing candidosis in denture users. © 2013 by the American College of Prosthodontists.

Influence of current density on crystalline structure and magnetic properties of electrodeposited Co-rich CoNiW alloys

The influence of current density, at the interval 5-100 mA cm-2, on the structural and magnetic properties of electrodeposited (Co 100-xNix)100-yWy alloys (x = 23-33.5 at. % Ni, y = 1.7-7.3 at. % W) was studied from a glycine-containing bath. W-content decreases with the increase of the current density magnitude. X-ray data have shown stabilization of hexagonal close packed, face centered cubic or a mixture of these structures by modulating the applied cathodic current density, for values lower than 50 mA cm-2. Two structural phase transitions were observed: one from hexagonal close packed to face centered cubic structural transition occurring for a current density of 20 mA cm -2, and another one, from cubic crystalline phase to amorphous state, which happens for values higher than 50 mA cm-2. These structural phase transitions seem to be associated with the W-content as well as average crystalline grain sizes that reduce with increasing the current density value. The grain size effect may explain the face centered cubic stabilization in Co-rich CoNiW alloys, which was initially assumed to be basically due to H-adsorption/incorporation. Magnetic properties of Co-rich CoNiW alloys are strongly modified by the current density value; as a result of the changes on the W-content and their structural properties© 2013 Elsevier B.V. All rights reserved.

Hot Brownian carriers in the Langevin picture: Application to a simple model for the Gunn effect in GaAs

We consider a charged Brownian gas under the influence of external, static and uniform electric and magnetic fields, immersed in a uniform bath temperature. We obtain the solution for the associated Langevin equation, and thereafter the evolution of the nonequilibrium temperature towards a nonequilibrium (hot) steady state. We apply our results to a simple yet relevant Brownian model for carrier transport in GaAs. We obtain a negative differential conductivity regime (Gunn effect) and discuss and compare our results with the experimental results. © 2013.

Non-Markovian expansion in quantum Brownian motion

We consider the non-Markovian Langevin evolution of a dissipative dynamical system in quantum mechanics in the path integral formalism. After discussing the role of the frequency cutoff for the interaction of the system with the heat bath and the kernel and noise correlator that follow from the most common choices, we derive an analytic expansion for the exact non-Markovian dissipation kernel and the corresponding colored noise in the general case that is consistent with the fluctuation-dissipation theorem and incorporates systematically non-local corrections. We illustrate the modifications to results obtained using the traditional (Markovian) Langevin approach in the case of the exponential kernel and analyze the case of the non-Markovian Brownian motion. We present detailed results for the free and the quadratic cases, which can be compared to exact solutions to test the convergence of the method, and discuss potentials of a general nonlinear form. © 2013 Elsevier B.V. All rights reserved.

Comportamento de poedeiras criadas a diferentes densidades e tamanhos de grupo em ambiente enriquecido

The objective of this work was to determine the behavioral differences among laying hens reared at different densities and group sizes, in an enriched environment. Isa Brownlaying hens with ages from 30 to 32-week-old, in small-sized and deformed pens, were used. Hens were raised during 28 days in bays with shavings bedding, perch and nest. Two group sizes were evaluated (6 and 12 fowls) and at two rearing densities (774 and 1,440 cm2 by fowl) in a factorial arrangement with three replicates. In fifteen-minute video footages, it was recorded the frequency and the expression period for the following behavior were recorded: feather scratching, sand bath, wing beating, drinking water, pecking, head scratching, earth scratching, eating, perching, leg stretching, pursuing, sitting, and nest visiting. The treatments and the interaction between them had significant effects. The six-hen group increased the frequency of behavior types that indicate fowl frustration, regardless of density. The group size is the most important factor for hen well-being.

Determinação de resíduo hormonal na carcaça de tilápia do nilo (Oreochromis niloticus) após reversão sexual

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise teórica e experimental de um método interferométrico de detecção de fase óptica, auto-consistente e com elevada faixa dinâmica, aplicado à caracterização de atuadores piezoelétricos flextensionais

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Análise teórica de uma nova técnica de processamento de sinais interferométricos baseada na modulação triangular da fase óptica

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Método de detecção interferométrica de fase, com baixa profundidade de modulação, aplicado à medição de deslocamentos nanométricos em atuadores e mini-manipuladores piezoelétricos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Demodulação de sinais interferométricos de saída de sensor eletro-óptico de tensões elevadas utilizando processador digital de sinais

Pós-graduação em Engenharia Elétrica - FEIS