Sobre interações escalares e vetoriais na teoria de Duffin-Kemmer-Petiau

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Soluções analíticas da equação de Duffin-Kemmer-Petiau

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Flag-dipole spinor fields in ESK gravities

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

S Q E D (4) and Q E D (4) on the Null-Plane

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Investigation of the conduction processes in PZT-based multiferroics: Analysis from Jonscher's formalism

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Involutive constrained systems and Hamilton-Jacobi formalism

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

Corrosion-fatigue life of commercially pure titanium and Ti-6Al-4V alloys in different storage environments

Statement of problem. Removable partial dentures are affected by fatigue because of the cyclic mechanism of the masticatory system ansi frequent insertion and removal. Titanium and its alloys have been used in the manufacture of denture frameworks; however, preventive agents with fluorides are thought to attack titanium alloy surfaces.Purpose. This study evaluated, compared, analyzed the corrosion-fatigue life of commercially pure titanium and Ti-6Al-4V alloy in different storage environments.Material and methods. For each metal, 33 dumbbell rods, 2.3 mm in diameter at the central segment, were cast in the Rematitan system. Corrosion-fatigue strength test was carried out through a universal testing machine with a load 30% lon er than the 0.2% offset yield strength and a combined influence of different: environments: in air at room temperature, with synthetic saliva, and with fluoride synthetic saliva. After failure, the number of cycles were recorded, and fracture surfaces were examined with on SEM.Results. ANOVA and Tukey's multiple comparison rest indicated that Ti-6Al-4V alloy achieved 21,269 cycles (SD = 8,355) against 19,157 cycles (SD = 3,624) for the commercially purr Ti. There were no significant differences between either metal in the corrosion-fatigue life for dry specimens, but when the solutions were present, the fatigue life was significantly reduced, probably because of the product-ion of corrosion pits caused by superficial reactions.

Higher-derivative non-Abelian gauge fields via the Faddeev-Jackiw formalism

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

VSR symmetries in the DKP algebra: The interplay between Dirac and Elko spinor fields

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Reproductive performance and reconception of nellore cows according to their pure- or cross-bred calves

Contents The objective of the present research was to evaluate the effect of a calf's genetic group on the productive and reproductive efficiency of its Nellore dam. Fixed-time artificial insemination was applied to 800 cows using semen extracted from Nellore, Simmental and Angus Red bulls. Four hundred eleven cows calved, producing 119 Nellore, 103 1/2Simmental-1/2Nellore and 189 1/2Nellore-1/2Angus Red calves. The second mating period, which paired Nellore cows with Simmental bulls, was initiated 10days after parturitions began and lasted for 5months. Based on the two successive parturitions, the cumulative parturition rate for calving periods of 3, 4 and 5months was calculated. Although no significant difference was observed for birth weight among the genetic groups, cross-bred calves weighed, on average, 10% more than did pure-bred calves at the age of 205days. Nellore dams experienced a gestation period that was 7days longer than did the cross-bred dams, and the former showed a higher parturition rate at 90 and 120days of the calving season, but not at 150days (calving rates of 80.6, 76.4 and 76.2% for mothers of Nellore, 1/2Nellore-1/2Angus Red and 1/2Nellore-1/2Simmental, respectively, p>0.05). At 90 and 120days, Nellore dams produced more kg of calf per mated dam. In conclusion, in a short breeding season, Nellore dams nursing pure-bred Nellore calves were found to have a higher biological efficiency compared with Nellore dams nursing cross-bred calves.

Spontaneous symmetry breaking in a spin-orbit-coupled f=2 spinor condensate

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

Questing mass dimension 1 spinor fields

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Potentiodynamic behaviour of CuA1Ag alloys in NaOH: a comparative study related to the pure metals electrochemistry

The mechanism of electrochemical oxidation of surface reformed CuA1Ag alloys having different composition of heat treatment, in 0.5 M NaOH was studied by means of cyclic polarization, constant potential electrolysis, ICP, AA, SEM and EDX. The surface reformation consisted of a repetitive triangular potential sweep (RTPS) between H 2 and O 2 evolution at 100 mV s -1 in the working solution itself, performed in order to increase the electrode roughness and obtain a quasi-stationary I/E profile in which the potentiodynamic behaviour of copper and silver was clearly revealed. The alloys suffer aluminum dealloying after such an RTPS. The quasi-stationary cyclic polarization curve exhibits a multiplicity of current peaks which have been related to the electrochemical reactions involving the pure alloying elements. Complex potential perturbation programmes in regions having different anodic and cathodic limits allowed the study of the mechanism of the electrochemical oxidation of the surface reformed alloys and the compare with that corresponding to the pure metals. The basic differences between the electro-oxidation processes of the surface reformed CuA1Ag alloys with respect to those established for the high purity alloying metals are the splitting of the peaks corresponding to the formation of the Cu(I) and Ag(I) species. © 1991.

Histomorphometric analysis of pure titanium implants with porous surface versus rough surface

The purpose of this study was to analyze the bone repair around commercially pure titanium implants with rough and porous surface, fabricated using powder metallurgy technique, after their insertion in tibiae of rabbits. Seven male rabbits were used. Each animal received 3 porous-surface implants in the left tibia and 3 rough-surface implants in the right tibia. The rabbits were sacrificed 4 weeks after surgery and fragments of the tibiae containing the implants were submitted to histological and histomorphometric analyses to evaluate new bone formation at the implant-bone interface. Means (%) of bone neoformation obtained in the histomorphometric analysis were compared by Student's t-test for paired samples at 5% significance level.. The results of the histological analysis showed that osseointegration occurred for both types of implants with similar quality of bone tissue. The histomorphometric analysis revealed means of new bone formation at implant-bone interface of 79.69 ± 1.00% and 65.05 ± 1.23% for the porous- and rough-surface implants, respectively. Statistically significant difference was observed between the two types of implants with respect to the amount new bone formation (p<0.05). In conclusion, the porous-surface implants contributed to the osseointegration because they provide a larger contact area at implant-bone interface.

Evaluation of pure and Ag-doped TiO2 films in the photocatalytic activity of phenol

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