XXXVII COMU Scientific Awards

[...] This year we accepted 41 scientific projects to apply for the traditional and renowned Oswaldo Cruz Awards, Panel Awards and Monograph Awards. All the projects were evaluated focusing to improve the medical formation, excellence in teaching, commitment to the research and to prepare qualifiedprofessional. [...

Local structural analyses on molten terbium fluoride in lithium fluoride and lithium–calcium fluoride mixtures

X-ray absorption fine structure (XAFS) measurements on terbium fluoride in molten lithium fluoride and in molten lithium–calcium fluoride mixtures, (e.g. 0.20TbF3–0.80LiF, 0.20TbF3–0.62LiF–0.18CaF2, 0.20TbF3–0.48LiF–0.32CaF2, 0.50TbF3–0.50LiF, and 0.50TbF3–0.38LiF–0.12CaF2), have been carried out. In the solid state, coordination number of terbium (Ni) and inter ionic distances between terbium and fluorine in the first neighbor (ri) are nearly constant in all mixtures. In 0.20TbF3–0.80LiF, 0.20TbF3–0.62LiF–0.18CaF2 and 0.50TbF3–0.50LiF mixtures, Ni's decrease from ca. 8 to 6 and ri's also decrease from ca. 2.29 to 2.26 Å on melting. On the other hands, in molten 0.20TbF3–0.48LiF–0.32CaF2 and 0.50TbF3–0.38LiF–0.12CaF2 mixtures, Ni's are slightly larger than 6 and ri's do not change. These facts correspond to the amount of F− supplied by solvent melts, i.e. the effect of CaF2 becomes predominant at bCaF2 > 0.32 in ternary 0.20TbF3–aLiF–bCaF2 mixtures and at bCaF2 > 0.12 in ternary 0.50TbF3–aLiF–bCaF2 mixtures

Elasticity Constants of Single Crystals of Nickel-Copper Alloys

Single crystals of Ni-Cu alloys were prepared by the Bridgman method of slow solidification, and Young\u27s moduli were measured at room temperature by a new microscopic method. From the measured values, Young\u27s moduli for the principal orientations were derived. Young\u27s modulus in[100]direction decreases at first with the addition of copper to nickel, reaches the minimum at about 10, the maximum at about 25 per cent copper, and then decreases with further increasing content of copper. The behavior of Young\u27s modulus in[110]direction is similar to that of E_, while in[111]direction it decreases monotonously. The three principal elastic coefficients S_, S_ and S_ were determined by using the data of compressibility for polycrystals of Ni, Cu and a Ni-Cu alloy containing 45 per cent of copper. Futhermore, the principal rigidity moduli were derived

On Young\u27s Modulus and Grain Size in Nickel-Copper Alloys

Young\u27s modulus and the grain size have been measured with 10 kinds of polycrystalline ferromagnetic nickel-copper alloys annealed at 700°, 800°, 900°, 1000°and 1100℃. The following empirical relation has been found between Young\u27s modulus E and the average area of crystal grains S : E = E_0 - B log S, where E_0 and B are constants. Young\u27s modulus vs. composition curves for alloys with the same grain size were not always similar to one another, but every curve showed a minimum. The composition corresponding to the minimum shifted toward the nickel side as the grain size became large. With the addition of copper, Young\u27s modulus of nickel with comparatively small grains increased, whereas that with comparatively large grains decreased. These results suggest that the complication of the so-far as observed Young\u27s modulus vs. composition curves for nickel-copper alloys may be due partly to the difference in the grain size of the individual specimens. Finally, the measured results were compared with those calculated by the formula derived by Voigt and Reuss

Growth Rates of Recrystallization in Polycrystalline Nickel-Copper Alloys

The recrystallization rates in polycrystalline nickel-copper alloys were measured isothermally. The velocity constant of crystal growth, K, was obtained from the slope of the linear portion of growth curve of recrystallized crystals. The relation between K and copper concentration was not always simple, and showed a maximum at the composition of about 15 weight per cent of copper. It was found that the relation between K and heating temperature follows Arrhenius equation from which the activation energy, Q, for the recrystallization could be obtained. The relation between Q and copper concentrations exhibited a minimum at the composition of about 12 per cent of copper