Peptídeos derivados da toxina bacteriana ParE: síntese, estrutura e ação inibitória sobre a atividade de topoisomerases

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Desenvolvimento de métodos para determinação de sulfonamidas, dipirona e citrato de sildenafil em matrizes diversas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Propriedades multifuncionais do CaCu3Ti4O12: estudo dos mecanismos e suas aplicações

Pós-graduação em Ciência e Tecnologia de Materiais - FC

Lattice effects in the quasi-two-dimensional valence-bond-solid Mott insulator EtMe3P[Pd(dmit)(2)](2)

The organic charge-transfer salt EtMe3P[Pd(dmit)(2)](2) is a quasi-two-dimensional Mott insulator with localized spins S = 1/2 residing on a distorted triangular lattice. Here we report measurements of the uniaxial thermal expansion coefficients alpha(i) along the in-plane i = a and c axis as well as along the out-of-plane b axis for temperatures 1.4 K <= T <= 200 K. Particular attention is paid to the lattice effects around the phase transition at T-VBS = 25 K into a low-temperature valence-bond-solid phase and the paramagnetic regime above where effects of short-range antiferromagnetic correlations can be expected. The salient results of our study include (i) the observation of strongly anisotropic lattice distortions accompanying the formation of the valence-bond-solid phase, and (ii) a distinct anomaly in the thermal expansion coefficients in the paramagnetic regime around 40 K. Our results demonstrate that upon cooling through T-VBS the in-plane c axis, along which the valence bonds form, contracts while the second in-plane a axis elongates by the same relative amount. Surprisingly, the dominant effect is observed for the out-of-plane b axis which shrinks significantly upon cooling through T-VBS. The pronounced anomaly in alpha(i) around 40 K is attributed to short-range magnetic correlations. It is argued that the position of this maximum, relative to that in the magnetic susceptibility around 70 K, speaks in favor of a more anisotropic triangular-lattice scenario for this compound than previously thought.

Thermal study of the solid-state reactions on Pt-15%Rh/Hg system

Thermogravimetry (TG), energy dispersive X-ray microanalysis (EDX), scanning electron microscopy (SEM), mapping surface and X-ray diffraction (XRD) were used for the study of solid-state reaction on Pt-15%Rh with electrodeposited mercury. The results suggest when heated the mercury film react with the Pt-15%Rh alloy to form intermetallics having different thermal stabilities indicated by three mass loss steps. The first mass loss step occurs between room temperature and 184 degrees C only the bulk Hg is removed and PtHg4, PtHg2 and RhHg2 were characterized by XRD. The second step, between 184 and 271 degrees C, was attributed to PtHg4 decomposition with formation of PtHg2 stabilized by RhHg2. The third step, between 271 and 340 degrees C, was attributed to decomposition of a solid-solution of PtHg2/RhHg2. The fourth step, between 340 and 600 degrees C, was ascribed to: (1) a thermal decomposition of PtHg2, formed by a PtHg eutectoid reaction (similar to 340 degrees C) on the surface and (2) Hg removal from a solid solution of Pt-15%Rh(Hg). (C) 2013 Elsevier B.V. All rights reserved.

Hygroscopic properties of solid agro-industrial by-products used in solid-state fermentation

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo das propriedades físicas de sistemas ferroelétricos com estruturas tipo Aurivillius

Pós-graduação em Ciência dos Materiais - FEIS

Estabilização da fase perovskita e propriedades estruturais de filmes finos relaxores do sistema PLZT

Pós-graduação em Ciência dos Materiais - FEIS

Estudo das propriedades ópticas de pós cerâmicos à base de Zn3Ga2Ge2O10: X% Cr3+ (X = 0 ; 0,5 ; 0,75 ; 1,0)

Ceramic powders based on Zn3Ga2Ge2O10: Cr3+ X% (X = 0.0; 0.5; 0.75; 1.0) were synthesized by solid-state reaction method. The gallium-zinc germanate doped with chromium presents an interesting property of phosphorescence, that means, it is capable of emitting light when excited by a source of radiation, and such emission remains for some time after stopping the source. For this reason, these materials can be widely applied in night-vision surveillance, (through the use of solar energy, for example), electronic devices screen, emergency routes signals, control panels indicators in dark environments, etc. In this job were considered different amounts of dopant in order to perform a comparison of structural and photoluminescent properties. For that, some analyses were performed on samples, such as XRD, FT-Raman, SEM, UV-vis and photoluminescence measurements (PL). Such analysis allowed to infer that the presence of chromium results in no phase transformation, so that the four compositions have the same set of phases: cubic, rhombohedral and hexagonal. Although the structure was not changed, chromium influences other properties / characteristics of these materials. Examples are: increase of band-gap, decrease of average particle size, small changes in binding energy checked by Raman and especially the increase of photoluminescent property. The chromium ions have great ease in replacing gallium ions in octahedral sites, resulting in emission of light with a wavelength of about 700 nm (infrared region), which is justified by the spin-forbidden 2E 4A2 transition. In other words, chromium is a favorable luminescent center, acting as a trap in the crystal structure, since it imprisons the excitation energy easily and releases it gradually, allowing the phosphorescence. It was observed that the composition ... (Complete abastract click electronic access below)