Resumo O mexilhão dourado (Limnoperna fortunei) e Corbicula fluminea são espécies invasoras consideradas bem estabelecidas nos rios do Brasil e da América do Sul. Além dos problemas ambientais resultantes deste processo de invasão, a questão econômica, especialmente nas hidrelétricas, é muito preocupante e mobilizou vários tipos de estudos sobre esses bivalves. A detecção e identificação desses organismos em sua fase adulta nos rios não são um problema, no entanto, a identificação de larvas de bivalves por métodos morfológicos habituais é difícil devido à similaridade extremamente conservada nestes estágios. O uso do PCR-RFLP se mostrou como um método molecular eficiente e ágil que permitiu a detecção de padrões diferentes no gel de agarose para os dois bivalves testados. O padrão do gel mostrou uma banda de 100 pb para L. fortunei que não foi detectado para C. fluminea. Desta forma com o uso de amostras de água é possível detectar os dois moluscos, o que pode ser uma ferramenta poderosa para programas de monitoramento ambiental em espécies aquáticas invasoras.

Abstract The golden mussel (Limnoperna fortunei) and Corbicula fluminea are considered well-established invasive species in the rivers of Brazil and South America. In addition to the environmental problems resulting from this invasion process, the economic issue, especially in hydroelectric dams, is very worrisome and has mobilized several types of studies on these invasive bivalves. The detection and identification of these organisms in their adult phase in the rivers is not a problem; however, the identification of bivalve larvae by usual morphological methods is difficult due to high similarity conserved in these stages. The use of PCR-RFLP has proven to be an efficient and agile molecular method that allowed the detection of different patterns in the agarose gel for the two bivalves tested. The gel pattern showed a 100 bp band for L. fortunei not detected for C. fluminea. Thus, it is possible to detect larvae of these species from water samples, which can be a powerful tool for environmental monitoring programs on aquatic invasive species.

ABSTRACT Mutant hemoglobins thermodynamic phase transitions (HbS, HbC, etc.) have been the causes of serious hemoglobinopathies that have been affecting mankind since the dawn of human race. HbS polymerization is the best known of these transitions and the original cause of sickle cell anemia. Hydroxyurea (HU, NH2CONHOH) is widely used as the main drug administered for the treatment of Sickle Cell Anemia (SCA). Several hypotheses have been raised on the effects of HU on SCA. The most widespread and accepted one points to the production of fetal hemoglobin by the bone marrow, hindering the polymerization of deoxygenated HbS. Moreover, recent studies have reported that the short term in vivo effects of the HU have not been elucidated. By ordinary techniques of Materials Science (scanning electron microscopy, viscoelasticity, viscosity measurements, DSC and weight loss) we assessed the anti-nucleating, depolymerizing, and antigelling direct effects of HU on suspensions and type I bovine collagen gels. Scanning electron microscopy (SEM) revealed that the addition of HU results in the disappearance of the percolating three-dimensional network typical of collagen gels. Vane Rheometry tests pointed to a reduction in the yield stress (σ0) by adding HU into collagen gels with a concentration of 2.2 % w/v. In the liquid phase (sol), suspensions increased viscosity over time but decreased with the addition of HU, highlighting the depolymerizing effect of this substance. The weight loss of the sols is also affect by the addition of HU probably related to the lowering of the interactions between collagen/water as HU is added. The DSC essays indicated changes in the Cp curves as HU is added to the gel, decreasing the structural relaxations commonly observed in those gels. As a result, HU showed an effect on the phase transition of the studied gel, strengthening the hypothesis of anti-nucleating and anti-gelling action thereof on physical, reversible gels, and possibly on physical, reversible gels of mutant hemoglobin (HbS).

Aragonite is a metastable polymorph of calcium carbonate found in mollusk’s shells, appearing in tiles and prismatic columns, cemented in a protein matrix - mainly proteins - that acts as a framework on which the aragonite is nucleated forming nacre, besides selecting the morphology of the nucleated cristaline phase. The presence of the mineralyzing organic matrix may affect osteoinductive properties of biogenic aragonite, hypothesis tested by combinated tests, comparing viability and bioactivity of biomineralizated aragonite and nacre. Bioactivity was observed by deposition of Ca-P (presumably calcium phosphate) on the surface of samples immersed in Simulated Body Fluid; biocompatibility was verified by adhesion with VERO cells; cytotoxicity and alkaline phosphatase activity assays were performed with human adipose stem cells (hASC). Samples were characterized by scanning electron microscopy and X-ray diffraction. Both materials showed similar behaviour on bioactivity assay; in contrast, exhibited different behaviours in the presence of hASC.

Applying the theories of Materials Science and Engineering to describe the composition and hierarchy of microstructures that comprise biological systems could help the search for new materials and results in a deeper insight into evolutionary processes. The layered microstructure that makes up the freshwater bivalve Limnoperna fortunei shell, an invasive specie in Brazil, was investigated utilizing SEM and AFM for the determination of the morphology and organization of the layers; and XRD was used to determine the crystalline phases of the calcium carbonate (CaCO3) present in the shell. The presence of the polymorphs calcite and aragonite were confirmed and the calcite is present only on the external side of the shell. The shell of L. fortunei is composed of two layers of aragonite with distinct microstructures (the aragonite prismatic layer and the aragonite sheet nacreous layer) and the periostracum (a protein layer that covers and protects the ceramic part of the shell). A new morphology of the calcite layer was found, below the periostracum, without defined form, albeit crystalline.

Os tijolos refratários do sistema Al2O3-SiC-C foram introduzidos nos revestimentos para carros-torpedo na década de 80. A formação de trincas paralelas à face quente desses tijolos com posterior lascamento da porção afetada é o principal motivo da redução da vida útil desse revestimento. As modificações microestruturais nesses tijolos, combinadas com esforços de natureza mecânica e térmica, são apontadas como a causa mais freqüente da fratura desses refratários. Os resultados da caracterização realizada em amostras de tijolos refratários novos, cuja formulação comercial foi intencionalmente modificada, indicaram que o tipo de resina fenólica, utilizado como ligante das partículas cerâmicas dos refratários para carro-torpedo, exerce efeitos significativos nas propriedades desses tijolos.

Al2O3-SiC-C bricks have been widely used for torpedo cars since the 80's. Crack formation parallel to the hot face of the Al2O3-SiC-C bricks followed by the spalling of the affected portion has been the main reason for the premature wear of the refractories. Microstructure changes, combined with mechanical and thermal stresses, have been pointed out as the cause for the fracture of these materials. The current results of laboratory tests used for characterizing four Al2O3-SiC-C bricks indicated, for the evaluated conditions, that the kind of resin has significant effect on the properties of Al2O3-SiC-C bricks.

Our hypothesis is that the action of aggregating and disaggregating substances in the blood can be detected and quantified by the Microplate Reader. To ascertain the validity of this hypothesis, we selected two types of blood: one that naturally presents erythrocyte aggregation (pig blood) and the other that does not present aggregation (bovine blood). One important reason for the choice of pig blood is that its erythrocyte aggregation resembles that of human blood. T. infestans saliva was added to the pig blood as a disaggregating substance, while bovine fibrinogen was added to the bovine blood as a substance that promotes erythrocyte aggregation. We investigated the dynamic viscosity (h) of these mammals' blood, of T. infestans saliva and of the absorption (A) by Microplate Reader, carrying out UV-Vis spectrophotometric assays of pig plasma with different concentrations of triatominae saliva and of bovine blood with different concentrations of fibrinogen. Our findings indicate that spectroscopic techniques such as the Microplate Reader complement and expand the study of blood rheology, erythrocyte sedimentation and aggregation.