Radiography of biological specimens with alpha particles and the CR-39 SSNTD

This work studies the alpha particle radiography technique in conjunction with the CR-39 SSNTD. The irradiations were made in the CV-28 cyclotron at IEN/CNEN/RJ using a 7 MeV/nucleon alpha particle beam. The best etch time to obtain radiographs was determined as six hours. A calibration curve was obtained, so to allow a quantitative interpretation of the images to be performed. Its behavior was checked by several experiments with other energy degrading materials. Several radiographs of “in-vitro” biological specimens were obtained. The results showed the potential capability of this technique for studies in paleontology.     

Nonconservation of muon number in a model of lepton structure

We speculate on a possible primary structure for leptons similar to the quark structure for hadrons, and thus propose a new possible approach to the study of these particles. A suppression mechanism is provided for the effects of the new interaction upon the muon anomalous magnetic moment and in the decay amplitude for μ → eγ.     

Transition to chaos in the conservative four-wave parametric interactions

In this work, we analyze the transition from regular to chaotic states in the parametric four-wave interactions. The temporal evolution describing the coupling of two sets of three-waves with quadratic nonlinearity is considered. This system is shown to undergo a chaotic transition via the separatrix chaos scenario, where a soliton-like solution (separatrix) that is found for the integrable (perfect matched) case becomes irregular as a small mismatch is turned on. As the mismatch is increased the separatrix chaotic layer spreads along the phase space, eventually engrossing most part of it. This scenario is typical of low-dimensional Hamiltonian systems.     

Activity Coefficients of Potassium Chloride and Sodium Chloride in the Quaternary System KCl-NaCl-Water-Ethanol

Activity coefficients of KCl and NaCl were determined in the quaternary system KCl-NaCl-water-ethanol, for 10 and 20% (w/w) ethanol in the solvent, from experimental electromotive force data. The molalities varied from 0.1 mol kg^–1 to near saturation and measurements were taken in the temperature range 20 to 50°C. The Pitzer-Simonson equations were used to describe the nonideal behavior of both electrolytes and the corresponding activity coefficients were determined for each solvent and temperature.     

Production of an antiproliferative furanoheliangolide by Lychnophora ericoides cell culture

This work reports for the first time the production a furanoheliangolide (goyazensolide) by plant cell culture. Monitoring of the goyazensolide metabolism revealed that the maximum production occurred during the lag phase of the Lychnophora ericoides callus culture. The antiproliferative activity of obtained goyazensolide was evaluated against seven cancer cell lines using MTT assay. The results revealed a potent cytotoxic activity for the furaheliangolide with IC50 values in the range of 0.06 microg/ml for CEM leukemia cells to 0.75 microg/ml for B16 melanome cells.     

Gold complexes with dithiothiophene ligands: a metal based on a neutral molecule

The gold complexes n-Bu4N[Au(alpha-tpdt)2] (5), n-Bu4N[Au(dtpdt)2] (4) and n-Bu4N[Au(tpdt)2] (6) based on new dithiothiophene ligands (alpha-tpdt= 2,3-thiophenedithiolate, dtpdt=2,3-dihydro-5,6-thiophenedithiolate and tpdt = 3,4-thiophenedithiolate) have been prepared and characterised. These gold(III) complexes are diamagnetic, but they can be oxidised with iodine to the paramagnetic compounds [Au(alpha-tpdt)2] (8), [Au(dtpdt)2] (7) and n-Bu4N[[Au(tpdt)2]n-2] (9), which were isolated as fine powders and which exhibit paramagnetic susceptibilities that are almost temperature independent with room temperature values of 2.5 x 10(-4), 2.0 x 10(-4) and 5 x 10(-4) emu x mol(-1), respectively. Interestingly, the neutral complex [Au(alpha-tpdt)2] (8) as a polycrystalline sample displays the properties of a metallic system with a room temperature electrical conductivity of 6 S x cm(-1) and a thermoelectric power of 5.5 microVK(-1); this is the first time that this metallic property has been observed in a molecular system based on a neutral species.     

Delayed specific luminescence of aromatic scintillators

A modified expression for the delayed specific luminescence of organic scintillators as a function of the incident-particle linear energy transfer is presented. Theoretical curves thus produced show a good fit to the experimental results obtained with doped polystyrene films irradiated with α particles of energy ranging from 1 to 5 MeV. The adjusted value for the bimolecular interaction parameter B_T for the different concentrations of solute in the films gives consistency to the assumptions made.     

Elemental distribution in breast tissue samples using X-ray fluorescence microtomography

Summary The X-ray fluorescence microtomography (XRFMT) is a non-destructive technique, based on the detection of X-ray fluorescence emitted by the elements in the sample, and it is used to complement other techniques for sample characterization. In this work some tissues of human breast (healthy tissue, benign tumor and malignant tumor) have been analyzed in order to verify the efficiency of the system in the determination of the elemental distribution in these types of samples. The experiments were performed at the X-ray fluorescence beam line (D09B-XRF) of the Brazilian Synchrotron Light Source (LNLS), Campinas, Brazil. A white beam was used for the excitation of the elements and an HPGe detector detected the fluorescence photons. The incident beam was monitored by an ionization chamber and a fast scintillator detector was used to detect the transmitted radiation. All the tomographies have been reconstructed using a filtered-back projection algorithm. In the tissues samples, the elements of higher concentration were Zn, Cu and Fe.     

A first-order level-2 phase transition in thermodynamic formalism

We show the existence of a phase transition at the level of measures for the generalized dimension of the maximal entropy measure in a model that was considered by F. Hofbauer and which is related to a model of M. Fisher. The model presented here is related to the one-dimensional Ising model in which a wall effect is assumed. In this situation, the problem has to be considered in the one-dimensional lattice . In general there is no first-order transition for the Ising model in the lattice , but under our assumptions such transitions can occur. The Ising model has the purpose of explaining the magnetization of ferromagnetic systems at low temperatures. The main difference of our result from a previous result of F. Hofbauer is that the transition is analyzed in the setting of the generalized dimension. This setting is more closely related to the observables. The main purpose of this paper is to explain another mathematical model for phase transition using the mathematical results obtained by F. Hofbauer. We also use results of the thermodynamic formalism in an essential way.