Educação ambiental e a experiência da Embrapa Florestas.

A educação ambiental tornou-se uma prática indispensável em todas as empresas e instituições públicas e privadas nas esferas municipal, estadual e federal. Este trabalho objetivou apresentar a experiência do Programa de Educação Ambiental da Embrapa Florestas (PREA), no período de 2001 a 2006. Durante seis anos de atividades, o PREA ministrou inúmeros cursos e palestras, conduziu grupos em trilhas ecológicas, participou de eventos, organizou encontros referentes a meio ambiente, realizou diagnósticos ambientais, estabeleceu parcerias de cooperação técnica com vários órgãos e empresas e publicou material didático sobre educação ambiental. Os resultados indicaram que a Embrapa Florestas, juntamente com seus parceiros, desenvolveu e aplicou métodos eficientes de educação ambiental e os transmitiu para um número significativo de pessoas.bitstream/CNPF-2009-09/41611/1/BPD29_CD.pd

Educação ambiental na trilha ecológica da Embrapa Florestas

bitstream/CNPF-2009-09/42612/1/Doc147.pdf1 CD-ROM

Study of overload effects in bainitic steel by synchrotron X-ray diffraction

This work presents an in-situ characterisation of crack-tip strain fields following an overload bymeans of synchrotron X-ray diffraction. The study is made on very fine grained bainitic steel, thus allowing avery high resolution so that small changes occurring around the crack-tip were captured along the crack plane atthe mid-thickness of the specimen. We have followed the crack as it grew through the overload location. Oncethe crack-tip has progressed past the overload event there is strong evidence that the crack faces contact in theregion of the overload event (though not in the immediate vicinity of the current locations of the crack tip) atKmin even when the crack has travelled 1mm beyond the overload location. It was also found that at Kmax thepeak tensile strain ahead of the crack-tip decreases soon after the overload is applied and then graduallyrecovers as the crack grows past the compressive region created by the overload

Fermi surface nesting in several transition metal dichalcogenides

By means of high-resolution angle resolved photoelectron spectroscopy (ARPES) we have studied the fermiology of 2H transition metal dichalcogenide polytypes TaSe2, NbSe2, and Cu0.2NbS2. The tight-binding model of the electronic structure, extracted from ARPES spectra for all three compounds, was used to calculate the Lindhard function (bare spin susceptibility), which reflects the propensity to charge density wave (CDW) instabilities observed in TaSe2 and NbSe2. We show that though the Fermi surfaces of all three compounds possess an incommensurate nesting vector in the close vicinity of the CDW wave vector, the nesting and ordering wave vectors do not exactly coincide, and there is no direct relationship between the magnitude of the susceptibility at the nesting vector and the CDW transition temperature. The nesting vector persists across the incommensurate CDW transition in TaSe2 as a function of temperature despite the observable variations of the Fermi surface geometry in this temperature range. In Cu0.2NbS2 the nesting vector is present despite different doping level, which lets us expect a possible enhancement of the CDW instability with Cu-intercalation in the CuxNbS2 family of materials.Comment: Accepted to New J. Phy

Residual stress control of multipass welds using low transformation temperature fillers

Low transformation temperature (LTT) weld fillers can be used to replace tensile weld residual stresses with compressive ones and reduce the distortion of single-pass welds in austenitic plates. By contrast, weld fillers in multipass welds experience a number of thermal excursions, meaning that the benefit of the smart LTT fillers may not be realised. Here, neutron diffraction and the contour method are used to measure the residual stress in an eight pass groove weld of a 304 L stainless steel plate using the experimental LTT filler Camalloy 4. Our measurements show that the stress mitigating the effect of Camalloy 4 is indeed diminished during multipass welding. We propose a carefully selected elevated interpass hold temperature and demonstrate that this restores the LTT capability to successfully mitigate residual tensile stresses

Polarization Selection Rules and Superconducting Gap Anisotropy in Bi2Sr2CaCu2O8Bi_2Sr_2CaCu_2O_8

We discuss polarization selection rules for angle-resolved photoemission spectroscopy in Bi2212. Using these we show that the ``hump'' in the superconducting gap observed in the $X$ quadrant in our earlier work is not on the main $CuO_2$ band, but rather on an umklapp band arising from the structural superlattice. The intrinsic gap is most likely quite small over a range of $\pm 10^\circ$ about the diagonal directions.Comment: 3 pages, revtex, 3 uuencoded postscript figure