Magnetocaloric Effect In The Rni5 (r = Pr, Nd, Gd, Tb, Dy, Ho, Er) Series

In this paper, the magnetocaloric effect in the hexagonal intermetallic compounds belonging to the RNi5 series was calculated using a Hamiltonian including the crystalline electrical field, exchange interaction, and the Zeeman effect. Experimental work was performed and the two thermodynamics quantities, namely, isothermal entropy change and adiabatic temperature change were obtained for polycrystalline samples using heat capacity measurements, and compared to the theoretical predictions.70131344281-134428-6Pecharsky, V.K., Gschneidner Jr., K.A., (1997) Phys. Rev. Lett., 78, p. 4494Gschneidner Jr., K.A., Pecharsky, V.K., (1997) Rare Earths: Science, Technology and Application III, , edited by R. C. Bautista, C. O. Bounds, T. W. Ellis, and B. T. Kilbourn (The Minerals, Metals and Materials Society, Warendale, PATegus, O., Bruck, E., Buschow, K.H.J., De Boer, F.R., (2002) Nature (London), 415, p. 150Wada, H., Tanabe, Y., (2001) Appl. Phys. Lett., 79, p. 20(2001) Appl. Phys. Lett., 79, p. 3302Wada, H., Morikawa, T., Taniguchi, K., Shibata, T., Yamada, Y., Akishige, Y., (2003) Physica B, 328, p. 114Von Ranke, P.J., De Oliveira, N.A., Gama, S., (2004) J. Magn. Magn. Mater., 277, p. 78Von Ranke, P.J., De Campos, A., Caron, L., Coelho, A.A., Gama, S., De Oliveira, N.A., unpublishedVon Ranke, P.J., De Oliveira, N.A., Gama, S., (2004) Phys. Lett. A, 320, p. 302Von Ranke, P.J., Lima, A.L., Nóbrega, E.P., Da Silva, X., Guimarães, A.P., Oliveira, I.S., (2001) Phys. Rev. B, 63, p. 024422Von Ranke, P.J., Pecharsky, V.K., Gschneidner, K.A., Korte, B.J., (1998) Phys. Rev. B, 58, p. 14436Buschow, K.H.J., Van Der Goot, A.S., (1971) Acta Crystallogr., Sect. B: Struct. Crystallogr. Cryst. Chem., 27, p. 1085Stevens, K.W.H., (1952) Proc. Phys. Soc., London, Sect. A, 65, p. 209Radwanski, R.J., Kim-Ngan, N.H., Kayzel, F.E., Franse, J.J.M., Gignoux, D., Schmitt, D., Zhang, F.Y., (1992) J. Phys.: Condens. Matter, 4, p. 8853Tishin, A.M., Magnetocaloric effect in the vicinity of phase transitions (1999) Handbook of Magnetic Materials, 12, pp. 395-524. , edited by K. H. J. Buschow (North-Holland Elsevier, Amsterdam, the Netherlands), Chap. 4Marzouk, N., Graig, R.S., Wallace, W.E., (1973) J. Phys. Chem. Solids, 34, p. 15Barthem, V.M.T.S., Gignoux, D., Schmitt, D., (1989) J. Magn. Magn. Mater., 78, p. 56Zhang, F.Y., Gignoux, D., Schmitt, D., Franse, J.J.M., Kayzel, F.E., Kim-Ngan, N.H., Radwanski, R.J., (1994) J. Magn. Magn. Mater., 130, p. 108Morellon, L., Algarabel, P.A., Ibarra, M.R., Del Moral, A., Gignoux, D., Schmitt, D., (1996) J. Magn. Magn. Mater., 153, p. 17Barthem, V.M.T.S., Gignoux, D., Nait-Saada, A., Schmitt, D., Takeuchi, A.Y., (1989) J. Magn. Magn. Mater., 80, p. 142Gignoux, D., Givord, D., Del Moral, A., (1976) Solid State Commun., 19, p. 891Andreeff, A., Valter, V., Grissmann, H., Kaun, L.P., Lipold, B., Mats, V., Franzkhaim, T., (1978) JINR Rapid Commun., 1978, pp. 14-11324Marzouk, N., Graig, R.S., Wallace, W.E., (1973) J. Phys. Chem. Solids, 34, p. 1

Economic analysis of an agrosilvipastoral system for a mountainous area in Zona da Mata Mineira, Brazil

The objective of this work was to evaluate the economic viability of an agrosilvipastoral system developed for Zona da Mata mountainous areas in Minas Gerais state, Brazil, as well as to compare different options for wood (Eucalyptus grandis and Acacia mangium) commercialization of the second thinning. The data were obtained from a 10 year-old agrosilvipastoral system established in four hectares at Embrapa Gado de Leite station in Coronel Pacheco, MG, Brazil. As evaluation criteria for the economic viability analysis, the adopted methods were the net present value (NPV) and the internal rate of return (IRR), both calculated at 6% interest rate. Despite the small difference, adding value to forest products increased the attractiveness of the proposed system. Considered separately, the agricultural activity was impracticable, whereas the forestry and livestock activities were independently viable. The studied system seems to be equally tolerant to price variations for forest and livestock products, as well as strongly tolerant to variations in production costs