Permutability of Backlund transformation for N=1 supersymmetric sinh-Gordon

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

de Sitter geodesics: reappraising the notion of motion

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

On the solutions of the position-dependent effective mass Schrodinger equation of a nonlinear oscillator related with the isotonic oscillator

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Higher order Painleve equations and their symmetries via reductions of a class of integrable models

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Type-II Backlund transformations via gauge transformations

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

3D calculation of Tucson-Melbourne 3NF effect in triton binding energy

As an application of the new realistic three-dimensional (3D) formalism reported recently for three-nucleon (3N) bound states, an attempt is made to study the effect of three-nucleon forces (3NFs) in triton binding energy in a non partial wave (PW) approach. The spin-isospin dependent 3N Faddeev integral equations with the inclusion of 3NFs, which are formulated as function of vector Jacobi momenta, specifically the magnitudes of the momenta and the angle between them, are solved with Bonn-B and Tucson-Melbourne NN and 3N forces in operator forms which can be incorporated in our 3D formalism. The comparison with numerical results in both, novel 3D and standard PW schemes, shows that non PW calculations avoid the very involved angular momentum algebra occurring for the permutations and transformations and it is more efficient and less cumbersome for considering the 3NF.

Effect of partial crystallization on the mechanical properties and cytotoxicity of bioactive glass from the 3CaO center dot P2O5-SiO2-MgO system

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

Scaling investigation for the dynamics of charged particles in an electric field accelerator

Some dynamical properties of an ensemble of trajectories of individual (non-interacting) classical particles of mass m and charge q interacting with a time-dependent electric field and suffering the action of a constant magnetic field are studied. Depending on both the amplitude of oscillation of the electric field and the intensity of the magnetic field, the phase space of the model can either exhibit: (i) regular behavior or (ii) a mixed structure, with periodic islands of regular motion, chaotic seas characterized by positive Lyapunov exponents, and invariant Kolmogorov-Arnold-Moser curves preventing the particle to reach unbounded energy. We define an escape window in the chaotic sea and study the transport properties for chaotic orbits along the phase space by the use of scaling formalism. Our results show that the escape distribution and the survival probability obey homogeneous functions characterized by critical exponents and present universal behavior under appropriate scaling transformations. We show the survival probability decays exponentially for small iterations changing to a slower power law decay for large time, therefore, characterizing clearly the effects of stickiness of the islands and invariant tori. For the range of parameters used, our results show that the crossover from fast to slow decay obeys a power law and the behavior of survival orbits is scaling invariant. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4772997]

Thermal behavior of Cu-Al alloys near the alpha-Cu-Al solubility limit

The thermal behavior of Cu-Al alloys with 17, 19 and 21 at.%Al was examined by differential thermal analysis (DTA), differential scanning calorimetry (DSC), X-ray diffractometry (XRD), optical microscopy (OM) and scanning electron microscopy (SEM). The presence of the gamma phase (Al4Cu9) was clearly detected for the Cu-19 at.%Al alloy and caused the alpha (2) phase disordering process in two stages. The tendency to increase the alpha (2) dissolution precipitates with the increase in the Al content seems to be reverted for compositions at about 21 at.%Al and the heating/cooling ratio seems to influence the thermal response of this process. The presence of the endothermic peak corresponding to the beta (1)--> beta transformation depends on an incomplete beta decomposition reaction. The variation of the heating rate showed that the beta (1)-->(alpha+gamma (1)) decomposition is the dominant reaction for alloys containing 19 and 21 at.%Al.

Effect of 4 mass% Ag addition on the thermal behavior of the Cu-9 mass% Al alloy

The effect of 4 mass% Ag addition on the thermal behavior of the Cu-9 mass% Al alloy was studied using differential scanning calorimetry (DSC), optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and X-ray diffractometry (XRD). The results showed that the presence of silver causes (Cu)-alpha+(alpha+gamma1)-->(Cu)-alpha+beta transformation to occur in two stages. In the first one, part of the produced beta phase combines with the precipitated Ag to give a silver-rich phase and in the second one the transformation is completed. The formation of this silver-rich phase seems to be enhanced at very low cooling rates.

On the reversed crystal growth of BaZrO3 decaoctahedron: shape evolution and mechanism

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

beta Phase transformations in the Cu-11mass%Al alloy with Ag additions

In the Cu-Al system, due to the sluggishness of the beta a dagger" (alpha + gamma(1)) eutectoid reaction, the beta phase can be retained metastably. During quenching, metastable beta alloys undergo a martensitic transformation to a beta' phase at Al low content. The ordering reaction beta a dagger" beta(1) precedes the martensitic transformation. The influence of Ag additions on the reactions containing the beta phase in the Cu-11mass%Al alloy was studied using differential scanning calorimetry and in situ X-ray diffractometry. The results indicated that, on cooling, two reactions are occurring in the same temperature range, the beta -> (alpha + gamma(1)) decomposition reaction and the beta -> beta(1) reaction, with different reaction mechanisms (diffusive for the former and ordering for the latter) and, consequently, with different reaction rates. For lower cooling rates, the dominant is the decomposition reaction and for higher cooling rates the ordering reaction prevails. on heating, the (alpha + gamma(1)) -> beta reverse eutectoid reaction occurs with a resulting beta phase saturated with alpha. The increase of Ag concentration retards the beta -> (alpha + gamma(1)) decomposition reaction and the beta -> beta(1) ordering reaction, which occurs in the same temperature range, becomes the predominant process.

Dynamics and cytochemistry of oogenesis in Astyanax fasciatus (Cuvier) (Teleostei, Characiformes, Characidae) from Rio Sapucaí, Minas Gerais State, Brazil

Oogenesis involves a set of transformations which are undergone by female germ cells These cells change into oogonias and then into mature oocytes. Sexually mature female fish were collected monthly, during one year, from the Sapucaí River, a tributary of the Rio Grande, which is part of the Furnas Reservoir in the state of Minas Gerais. During the several stages of maturation, we observed small round oogonias with a large nucleus, a single nucleolus, and weakly stained cytoplasm with eosinophilic granules. The primary oocytes showed a large basophilic nucleus, with a developed peripheral nucleolus and a reduced cytoplasm. The previtellogenic oocytes presented voluminous cytoplasm and nucleus with several small peripheral nucleoli. The oocytes underwent vitellogenesis with the development of the zona radiata and the follicle cells. Their cytochemical reactions indicated that the two layers of the zona radiata of A. fasciatus contained proteins and polysaccharides. The initially squamous follicle cells, became cuboidal. In mature oocytes, the nucleus moved toward the periphery, next to the micropyle, and the yolk granules formed by proteins, fulfilled the cytoplasm. The clear unstained vesicles are likely to be the cortical alveoli in the perivitelline region.

Dynamics and cytochemistry of oogenesis in Leporinus striatus Kner (Teleostei, Characiformes, Anostomidae) from the Rio Sapucaí, Minas Gerais State, Brazil

Oogenesis involves a sequense of transformations which are undergone by female germ cells. These cells change into oogonias and then into mature oocytes. Sexually mature females were collected monthly, during one year, from the Rio Sapucaí, tributary of the Rio Grande, which is part of the Furnas Reservoir system in the state of Minas Gerais. The observed material showed that oogonias were small spherical cells, had a big spherical nucleus, with a single nucleolus, and weakly stained cytoplasm with eosinophilic granules (FG stained), which indicate their protein content. The primary oocytes showed a big basophilic nucleus, with a large peripheral nucleolus, and several smaller nucleoli. They show a reduced cytoplasmic content. The previtellogenic oocytes presented voluminous cytoplasm and nucleus with several small peripheral nucleoli. The oocytes underwent vitellogenesis with the development of the zona radiata and the follicle cells. The zona radiata had two layers, the outer and the inner, which showed its protein content when stained with CM and FG techniques. TB pH 2.5 and pH 4.0 staining showed that oocytes undergoing vitellogenesis presented weakly stained cytoplasm and peripheral cytoplasmic vesicles. The follicle cells that were squamous became cuboidal. In mature oocytes, the yolk granules that filled the cytoplasm became green and blue when stained with FG and CM techniques, indicating their protein content. The perivitclline region showed rosy stained vesicles (TB pH 2.5 and pH 4.0) spread among the weakly stained peripheral vesicles, which seemed to be the cortical alveoli. The zona radiata cells, CM and FG stained, still showed two layers like the oocytes from the previous stage, but thicker.

Addition of sedimentary rock to kaolinitic clays: influence on sintering process

Foram avaliadas, durante o processo de sinterização, as propriedades mecânicas de peças cerâmicas a base de argila com adição de rocha sedimentar. Foram preparados corpos de prova com 0, 20, 40, 60 e 80% em peso de rocha adicionada ao material argiloso. As peças foram sinterizadas nas temperaturas de 500, 800, 900, 1000, 1100 e 1200 °C e, posteriormente, submetidas à análise de difração de raios X e a ensaios tecnológicos Os resultados de difração de raios X mostram que a rocha sedimentar apresenta argilominerais micáceos enquanto o material argiloso possui a caulinita como fase principal. Técnicas de análises térmicas e difração de raios X das diferentes misturas mostram reações que indicam transformação (inversão do quartzo), decomposição (perda de hidróxidos) e formação de fase (mulita) durante o aquecimento das amostras. Os ensaios tecnológicos mostram que a adição da rocha sedimentar melhora algumas propriedades do material sinterizado, auxiliada pela presença de fundentes. Entretanto, a presença de quartzo na rocha dificulta a formação da fase mulita. A formação de novas fases e as transformações ocorridas no aquecimento e resfriamento das amostras ajuda explicar as propriedades tecnológicas dos materiais cerâmicos.