Projectile breakup dynamics for (6)Li+(59)Co: Kinematical analysis of alpha-d coincidences

A study of the kinematics of the alpha-d coincidences in the (6)Li + (59)Co system at a bombarding energy of E(lab) = 29.6MeV is presented. With exclusive measurements performed over different angular intervals it is possible to identify the respective contributions of the sequential and direct projectile breakup components. The angular distributions of both breakup components are fairly well described by the Continuum-Discretized Coupled-Channels framework (CDCC). Furthermore, a careful analysis of these processes using a semiclassical approach provides information on both their lifetime and their distance of occurrence with respect to the target. Breakup to the low-lying (near-threshold) continuum is delayed, and happens at large internuclear distances. This suggests that the influence of the projectile breakup on the complete fusion process can be related essentially to the direct breakup to the (6)Li high-lying continuum spectrum.

High specific surface area LaFeCo perovskites-Synthesis by nanocasting and catalytic behavior in the reduction of NO with CO

LaFe(1-x)CO(x)O(3) perovskites were conventionally or nanocasting synthesized. The nanocasting involved the preparation of a micro-mesoporous carbon mould using a Silica Aerosil 200 and a carbon source. Then, perovskites were carbon cast at 800 degrees C. The solids were characterized by XRD, N(2) sorption, FTIR, TGA/DTG, SEM and TEM. N(2) sorption evidenced that the nanocast perovskites did not show significant intraparticle porosity in despite of their enhanced (30-50 m(2)/g) specific surface area (SSA). Nevertheless, TEM images, XRD and Rietveld refinement data showed that the solids are constituted at least by 97 wt% of perovskite phase and by agglomerates smaller than 100 nm constituted by crystallites of about 6 nm. TGA/DTG results demonstrated carbon oxidation during the perovskite formation, thus eliminating the template effect and facilitating the occurrence of sintering, which limited the SSA increase. The nanocast perovskites were more active in the reduction of NO than the uncast ones, behavior that was attributed to the increase in their SSA that allows the exposure of a higher number of accessible active sites. However, the perovskite composition and the presence of impurities can reduce the effect of the improvement of the textural properties. The nanocast perovskites also showed high thermal and catalytic stability, corroborating their potential as catalysts for the studied reaction. (C) 2009 Elsevier B.V. All rights reserved.

Structural effects and hydrogen bonds on N,N `-di(methoxycarbonylsulfenyl)urea, [CH(3)OC(O)SNH](2)CO, studied by experimental and theoretical methods

Pure N,N`-di(methoxycarbonylsulfenyl)urea, [CH(3)OC(O)SNH](2)CO, is quantitatively prepared by the hydrolysis reaction of CH(3)OC(O)SNCO and characterized by (1)H NMR, GC-MS and FTIR spectroscopy techniques. Structural and conformational properties are analyzed using a combined approach with data obtained from X-ray diffraction, vibrational spectra and theoretical calculation methods. The IR and Raman spectra for normal and deuterated species are reported. The crystal structure of [CH(3)OC(O)SNH](2)CO was determined by X-ray diffraction methods. The substance crystallizes in the orthorhombic P2(1)2(1)2 space group with a = 9.524(2), b = 12.003(1), c = 4.481 (1) angstrom, and Z = 2 moieties in the unit cell. The molecule is sited on a twofold crystallographic axis (C(2)) parallel to c and shows the anti-anti conformation (S-N single bonds antiperiplanar with respect to the opposite C-N single bonds in sulfenyl-urea-sic group). Neighboring molecules are arranged in a chain motif that extends along the C(2)-axis and is held by bifurcated NH center dot center dot center dot O center dot center dot center dot HN intermolecular bonds. A local planar symmetry is observed in the crystal for the central -SN(H)C(O)N(H)S- skeleton. Experimental and calculated data allow to trace this structural feature to the occurrence of N-H center dot center dot center dot O=C hydrogen bonding interactions. Calculated vibrational and structural properties are in good agreement with the experimentally determined features. (C) 2008 Elsevier B.V. All rights reserved.

Investigation of the CO tolerance mechanism at several Pt-based bimetallic anode electrocatalysts in a PEM fuel cell

The electrocatalysis of CO tolerance of Pt/C, PtRu/C, PtFe/C, PtMo/C, and PtW/C at a PEM fuel cell anode has been investigated using single cell polarization and online electrochemical mass spectrometry (EMS) measurements, and cyclic voltammetry, X-ray diffraction (XRD), in situ X-ray absorption near edge structure (XANES) analyses of the electrocatalysts. For all bimetallic electrocatalysts, which presented higher CO tolerance, EMS results have shown that the production of CO(2) start at lower hydrogen electrode overpotentials as compared to Pt/C, confirming the occurrence of the so-called bifunctional mechanism. On the other hand, XANES results indicate an increase in the Pt 5d-band vacancies for the bimetallic catalysts, particulary for PtFe/C, this leading to a weakening of the Pt-CO bond, helping to increase the CO tolerance (the so-called electronic effect). For PtMo/C and PtRu/C supplied with H(2)/CO, the formation of CO(2) is observed even when the cell is at open circuit, confirming some elimination of CO by a chemical process, most probably the water gas shift reaction. (C) 2008 Elsevier Ltd. All rights reserved.

Characterization of Atrazine-Loaded Biodegradable Poly(Hydroxybutyrate-Co-Hydroxyvalerate) Microspheres

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

Micropartículas de poli (ácido lático-co-ácido glicólico) obtidas por spray drying para a liberação prolongada de metotrexato

Methotrexate (MTX) is a drug used in the chemotherapy of some kind of cancers, autoimmune diseases and non inflammatory resistant to corticosteroids uveits. However, the rapid plasmatic elimination limits its therapeutic success, which leads to administration of high doses to maintain the therapeutic levels in the target tissues, occurring potential side effects. The aim of this study was to obtain spray dried biodegradable poly-lactic acid co-glycolic acid (PLGA) microparticles containing MTX. Thus, suitable amounts of MTX and PLGA were dissolved in appropriate solvent system to obtain solutions at different ratios drug/polymer (10, 20, 30 and 50% m/m). The physicochemical characterizing included the quantitative analysis of the drug using a validate UV-VIS spectrophotometry method, scanning electron microscopy (SEM), infrared spectrophotometry (IR), thermal analyses and X-ray diffraction analysis. The in vitro release studies were carried out in a thermostatized phosphate buffer pH 7.4 (0.05 M KH2PO4) medium at 37°C ± 0.2 °C. The in vitro release date was subjected to different kinetics release models. The MTX-loaded PLGA microparticles showed a spherical shape with smooth surface and high level of entrapped drug. The encapsulation efficiency was greater then 80%. IR spectroscopy showed that there was no chemical bond between the compounds, suggesting just the possible occurrence of hydrogen bound interactions. The thermal analyses and X-ray diffraction analysis shown that MTX is homogeneously dispersed inside polymeric matrix, with a prevalent amorphous state or in a stable molecular dispersion. The in vitro release studies confirmed the sustained release for distinct MTX-loaded PLGA microparticles. The involved drug release mechanism was non Fickian diffusion, which was confirmed by Kornmeyer-Peppas kinetic model. The experimental results demonstrated that the MTX-loaded PLGA microparticles were successfully obtained by spray drying and its potential as prolonged drug release system.

Occurrence of anti-Neospora caninum and anti-Toxoplasma gondii IgG antibodies in goats and sheep in western Maranhão, Brazil

A neosporose e a toxoplasmose são doenças parasitárias que podem causar problemas reprodutivos em caprinos e ovinos. O objetivo deste estudo foi determinar a ocorrência de anticorpos IgG anti-Neospora caninum e anti-Toxoplasma gondii em caprinos e ovinos dos municípios de Amarante do Maranhão e Buritirana, microrregião de Imperatriz, Oeste maranhense, Nordeste do Brasil, bem como avaliar fatores associados à infecção por esses agentes etiológicos. Amostras de sangue de 110 animais (46 caprinos e 64 ovinos), provenientes de cinco propriedades, foram coletadas, e a reação de imunofluorescência indireta utilizada para o diagnóstico sorológico. Das 46 amostras de caprinos, 17,39% (n = 8) apresentaram anticorpos anti-N. caninum e 4,35% (n = 2) anti-T. gondii, enquanto das 64 amostras de ovinos, 4,69% (n = 3) e 18,75% (n = 12) apresentaram anticorpos anti-N. caninum e anti-T. gondii, respectivamente. Não houve diferença significativa, considerando-se a presença de gato e/ou cão na propriedade e assistência veterinária para ambos os agentes estudados. Entretanto, suplementação alimentar e presença de animais com problemas reprodutivos diferiram significativamente (p < 0,05) em ovinos e caprinos, respectivamente. Os resultados do presente estudo demonstraram que caprinos e ovinos, da região Oeste do Maranhão são expostos aos coccídios N. caninum e T. gondii. Essa é a primeira evidência desses agentes em pequenos ruminantes nessa região.

Co-cultivation of plant cells as a technique for the elicitation of secondary metabolite production

Cells of Mikania glomerata, Cephaelis ipecacuanha and Maytenus aquifolia were co-cultured in a two-phase system using filter paper as a solid support. The species were co-cultured in all possible paired combinations. Interaction between Mikania and Maytenus cells resulted in increased biomass production of Maytenus cells, but the friedelin content was reduced. Co-cultivation of Cephaelis and Mikania cells enhanced coumarin content, but inhibited the growth of Mikania cells. However, yield of emetine as well as Cephaelis biomass accumulation were positively stimulated by the co-cultivation. Results indicate a possible occurrence of allelopathy in such a system.

Efeitos de vocalizações de co-específicos e do escuro sobre o ritmo circadiano da atividade motora em sagüis (Callithrix jacchus)

The principal zeitgeber for most of species is the light-dark photocycle (LD), though other environment factors as food availability, temperature and social cues may act. Daily adjustment of the circadian pacemaker may result from integration of environmental photic and non-photic cues with homeostatic cues. Characterization of non-photic effects on circadian timing system in diurnal mammals is scarce in relation to nocturnal, especially for ecologically significant cues. Thus, we analyzed the effect of conspecific vocalizations and darkness on circadian activity rhythm (CAR) in the diurnal primate Callithirx jacchus. With this objective 7 male adults were isolated in a room with controlled illumination, temperature (26,8 ± 0,2°C) and humidity (81,6 ± 3,6%), and partial acoustic isolation. Initially they were under LD 12:12 (~300:2 lux), and subsequently under constant illumination (~2 lux). Two pulses of conspecific vocalizations were applied in total darkness, separated by 22 days, at 7:30 h (external time) during 1 h. They induced phase delays at circadian times (CTs) 1 and 10 and predominantly phase advances at CTs 9 and 15. After that, two dark pulses were applied, separated by 14 days, during 1 h at 7:30 h (external time). These pulses induced phase delays at CTs 2, 3 and 18, predominantly phase advances at CTs 8, 10 and 19, and no change at CT 14. However, marmosets CAR showed oscillations in endogenous period and active phase duration influenced by vocalizations from animals outside the experimental room, which interfered on the phase responses to pulses. Furthermore, social masking and relative coordination with colony were observed. Therefore, phase responses obtained in this work cannot be attributed only to pulses. Afterwards, pulses of conspecific vocalizations were applied in total darkness at 19:00 h (external time), during 1 h for 5 consecutive days, and after 21 days, for 30 consecutive days, on attempt to synchronize the CAR. No animal was synchronized by these daily pulses, although oscillations in endogenous period were observed for all. This result may be due to habituation. Other possibility is the absence of social significance of the vocalizations for the animals due to random reproduction, since each vocalization has a function that could be lost by a mixture of sounds. In conclusion, conspecific vocalizations induce social masking and relative coordination in marmosets CAR, acting as weak zeitgeber

Macrofauna de ambientes não consolidados adjacentes à recifes da área de proteção ambiental dos recifes de corais Rio Grande do Norte, Brasil

This study aimed to characterize, for the first time, the benthic invertebrates that inhabit the region of soft bottoms adjacent to the APARC reefs in order to situate them as an important component of infralittoral coastal areas of Northeast Brazil. Soft bottoms areas of APARC corresponds to infralittoral zones vegetated by seagrass Halodule wrightii and unvegetated infralittoral zones, both subjected to substantial hydrodynamic stress. Through scuba diving, biological and sedimentary samples of both habitats were analyzed, with a cylindrical sampler. We identified 6160 individuals belonging to 16 groups and 224 species. The most abundant macrofaunal group was Polychaeta (43%), followed by Mollusca (25%) and Crustacea (14%), what was expected for these environments. In the first chapter, regarding vegetated areas, we tested three hypotheses: the existence of differences in the faunal structure associated with H. wrightii banks submitted to different hydrodynamic conditions; the occurrence of minor temporal variations on the associated macrofauna of banks protected from hydrodynamic stress; and if the diversity of macrofauna is affected by both benthophagous predators and H. wrightii biomass. It was observed that macrofauna associated at the Exposed bank showed differences in structure when comparing the Protected bank, the granulometry of the sediments, that co-varies with the hydrodynamism, was the cause of these variations. The results also pointed to a lower temporal variation in the macrofaunal structure on the Protected bank and a negative relation between macrofaunal and benthophagous fish abundance. At the Exposed bank, a greater faunal diversity was observed, probably due to the higher seagrass biomass. The second chapter compares the vegetated and non-vegetated areas in order to test the hypothesis that due to greater seasonal stability in tropical environments, seagrass structure would act to distinguish the vegetated and non-vegetated areas macrofauna, over time. It was also expected that depositivores were the most representative invertebrates on non-vegetated environments, on the assumption that the seagrass bank would work as a source of debris to adjacent areas, enriching them. Considering all sampling periods, the total macrofauna abundance and diversity were higher in vegetated areas, when compared to non-vegetated ones. Seasonally, the structural complexity provided by Halodule differentiated more clearly the fauna from vegetated and non-vegetated areas, but only at the climatic extremes, i.e. Dry season (extreme climatic stability, with low hydronamism variation) and Rainy season (great hydrodynamism variation and probably vegetated bank burial). Furthermore, the high organic matter levels measured in the sandy banks coincided with an outstanding trophic importance of deposit feeders, proving the debris-carrying hypothesis. The last chapter focused on the non-vegetated areas, where we tested that the hypothesis infaunal halo in tropical reefs depending on local granulometry. In this context, we also tested the hypothesis that benthophagous fish predation would have an effect on the low abundance of macrofaunal groups due to the high hydrographic stress, thus allowing other predatory groups to have greater importance in these environments. Proving the hypothesis, no spatial variation, both on abundance families neither on community structure, occur along distance of the edge reefs. However, we found that complex combinations of physical factors (grain size and organic matter levels originated from local hydronamic conditions) covary with the distance from the reefs and has stronger influence on macrofauna than considered biological factors, such as predation by benthophagous fishes. Based on the main results, this study shows that unconsolidated areas around APARC reefs are noteworthy from an ecological and conservational point of view, as evidenced by the biota-environment and organismal relations, never before described for these areas

Anoftalmia clínica bilateral associada à hidrocefalia congênita em cão

A ausência completa do bulbo ocular é muito rara em cães e gatos, enquanto a hidrocefalia é comumente observada como distúrbio congênito em cães de raças miniatura ou braquicefálicas, com menos de um ano de idade. O presente trabalho relata a ocorrência de anoftalmia clínica bilateral associada à hidrocefalia congênita em um cão da raça poodle, sendo este o primeiro relato de caso da associação dessas alterações no Brasil.

Occurrence of Aggregatibacter actinomycetemcomitans in Brazilian indians from Umutina Reservation, Mato Grosso, Brazil

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

Aquatic macrophyte distribution in relation to water and sediment conditions in the Itaipu Reservoir, Brazil

Aquatic macrophyte community distribution along the eastern shoreline of the Itaipu Reservoir (one of the South America's largest impoundments) is described in relation to limnological and sedimentological factors. The central body of the reservoir is mesotrophic, while the arms (flooded influent river valleys) along the eastern shore may be oligo-mesotrophic to eutrophic, depending on time of year and sub-catchment characteristics. Macrophyte community composition and species cover were surveyed at 30 sites in four arms, in relation to sediment total P and organic matter; underwater light regime; and water total P and Kjeldahl N concentration, alkalinity, conductivity, depth and pH. Seventeen euhydrophyte and six emergent macrophyte species were recorded. Large stands of Egeria najas dominated the euhydrophyte vegetation, together with free-floating weed species (Pistia stratiotes Linn., Salvinia auriculata Aublet and Eichhornia crassipes (Mart.) Solms.). Canonical Correspondence Analysis of the data showed that two sets of variables were important predictors of aquatic macrophyte community structure. Floating macrophyte assemblage was closely related to concentration of nutrients in both water and sediment, while light penetration was the strongest predictor of submerged species occurrence. Although a large number of potential nuisance species were present, dense growths were restricted to shallower areas of the Itaipu Reservoir, causing localised problems. The possibility of increasing interference by these plants with fisheries, recreational use, transport and hydroelectricity generation suggests a need for continued monitoring of weed distribution and abundance, and investigation of appropriate management measures.

Changes in ichthyofauna composition along a gradient from clearwaters to blackwaters in coastal streams of Atlantic forest (southeastern Brazil) in relation to environmental variables

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