In situ,ex situ EBSD and HR TEM analyses of primary, secondary and tertiary twin development in an Mg 4 wt Li alloy

This study presents experimental evidence for the sequence of activation and the evolution of primary tension TTW , secondary compression CTW and tertiary double twinning DTW in an extruded Mg 4 wt Li alloy during uniaxial compression by means of in situ and ex situ EBSD and HR TEM. In situ EBSD analysis reveals that the secondary CTWs propagate very slowly ,while the tertiary DTWs propagate faster once nucleated. Thereby, when DTW ing overtakes the CTW, CTW boundary migration stops, indicating that the thickness of the CTW is limited by the onset of internal DTW ing.This finding confirms some prior proposals based on post mortem analyses. High resolution HR TEM analysis of a 18 compressed sample reveals significant basal slip activity and a high amount of basal stacking faults within the primary TTW as well as within the secondary CTW. Additionally, the HR TEM analysis showed a large amount of basa ldislocations within the area of the CTW DTW transition.These findings give strong experimental evidence that the observed predominance of type 1 DTW ing is related to the dissociation of extended basal dislocation

Contaminação por mercúrio em sedimento e em moluscos do Pantanal, Mato Grosso, Brasil Mercury contamination in sediment and in molluscs of Pantanal, Mato Grosso, Brazil

<abstract language="eng">The total level of mercury detected in the sediment and in the tissues of molluscs from the Bento Gomes basin, although low, have shown that the mercury used in the gold mining activities in the Poconé wetlands has contaminated those aquatic habitats in Pantanal. From 69 sediment samples analyzed, 26 % (N = 18) have shown levels ranging from 0.01 to 0.25µg.g-1 of mercury (moist weight). Mercury levels analyzed in 54 samples of mollusc tissues (Ampullaria scalaris Orbigny, 1835; A. canaliculata Lamarck, 1819 and Marisa planogyra Pilsbry, 1933) have shown that 30% (N = 16) were contaminated with levels ranging from 0.02 to 1.16µg.g-1 moist weight. This study shows that the mercury used in digs for gold mining and released into the environment has reached the habitats of Pantanal spread from the sediment into the molluscs living in the region

The Effects of University Patenting and Licensing on Downstream R&D Investment and Social Welfare

A central argument behind the Bayh-Dole Act presumed that firms had no incentives to invest in downstream R&D aimed at developing university inventions committed to the public domain. The empirical evidence on university patenting and licensing is partly at odds with the premises of this argument. Non-exclusive licensing of university patents has been common and lucrative, and in the area of biomedical technologies university patents and licensing restrictions may be a hindrance to downstream R&D, rather than a stimulus. The paper presents a model of R&D competition based on a university invention where appropriability conditions are defined by the patentability of downstream innovations and imitation opportunities. A comparison of equilibria under “open access” to university inventions and under “university patenting” shows that only under restrictive conditions the latter regime results in increased R&D investment and social welfare. In general, university licensing royalties are therefore a poor gauge of social welfare gains from university patenting. Copyright Springer Science+Business Media, LLC 2006university patents, R&D competition, Bayh-Dole Act, downstream innovation, O310, O340,