The oxidative behaviour of natural pentlandite (FeNi)9S8 has been studied by thermogravimetry (TG) and differential thermal analysis (DTA) in a dynamic oxygen atmosphere (0.21 min−1) over the temperature range 20–1000°. Gaseous products were analysed by a coupled quadrupole mass spectrometer. The reaction products at various intermediate temperatures were characterised by X-ray diffractometry and chemical analysis. A reaction sequence has been deduced, in which in the temperature range 460–700° pentlandite breaks down with the formation of Fe2O3, NiSO4, NiO, NiS and NiFe2O4; FeSO4 was also formed but decomposed above 640°. Beyond 700° NiS was completely oxidised, and NiSO4 decomposed slowly. Another sulphide phase, possibly Ni3±xS2, was formed at 740° and completely oxidised at 790°, and above 800° NiSO4 decomposed completely leaving only Fe2O3, NiO and NiFe2O4 as stable products.
Authors:C. Tharp, J. Kelly, J. Morris, C. Baskett, V. Spate, M. Mason, T. Cheng, and T. Nichols
Chronic dietary deficiency of selenium has been shown to be associated with degenerative heart disease in production animals
in the U.S. and in the human in parts of China. In the latter, subjects in the endemic areas suffer high rates of a cardiomyopathy
known as Keshan's Disease which is normally fatal in early adulthood and can be prevented, or reversed in its early stages,
via selenium supplementation. Selenium, as the active moiety in the enzyme glutathione peroxidase, protects against oxidative
attack of cell membranes by peroxides formed during normal metabolism. In this study, we investigated the distribution of
selenium in healthy porcine and bovine heart tissue freshly collected at slaughter. The whole heart was perfused with DI water
and carefully de-fatted. Representative samples of left and right atria and ventricles and the interventricular septum were
collected, lyophilized and homogenized prior to preparing replicate samples for analysis. Replicates were analyzed for selenium
via an INAA scheme employing a 5, 15 and 25 second irradiation (φth = 8·1013 n·cm−2·s−1), decay and real-time count (77mSe,T1/2=17.4 s), respectively, using high-resolution gamma-ray spectroscopy with Westphal pulse pile-up correction. Selenium distribution
will be discussed relative to differentiated function and oxygenation of the specific tissues.
Authors:D. Hunt, J.P. Chambers, A. Behpouri, S.P. Kelly, L. Whelan, M. Pietrzykowska, F. Downey, P.F. McCabe, and C.K.-Y. Ng
Brachypodium distachyon is emerging as the model species for temperate monocotyledonous grasses of the Pooideae, and the genome of the B. distachyon community inbred line Bd21 has recently been sequenced. Here, we report the development of a procedure for the efficient establishment of a cell suspension culture derived from calli. We show that embryogenic potential is maintained in 3-month-old cultures as the cells were positively labelled by the monoclonal antibody, JIM8 which recognizes a carbohydrate epitope often present in arabinogalactan proteins found in the cell walls of cells in embryogenic cultures. Additionally, we were able to regenerate plants from these cell suspension cultures. The cell suspension culture we have established can also be used in studies on plant programmed cell death (PCD). Our results clearly demonstrate that B. distachyon cells can undergo apoptosis-like PCD (AL-PCD) as visualised by the characteristic retraction of the protoplast from the cell wall. As B. distachyon is genetically related to important temperate cereal grass crops like wheat and barley, the ability to utilise cell suspension cultures of B. distachyon to dissect the underlying mechanisms PCD will have important implications for understanding developmental processes in economically important cereal crops.
Authors:Kelly C. Teixeira, Gabriela F. Moreira, Welber G. Quirino, Cristiano Legnani, Raigna A. Silva, Marco Cremona, Hermi F. Brito, and Carlos A. Achete
The improvement of operational lifetime and efficiency of organic light-emitting devices has stimulated many studies focused on the mechanisms responsible for their degradation. Such instabilities can be induced by several factors such as (i) current flow and heating, (ii) chemical reactions, (iii) self-conversion of the charge transporting molecules to cation, anion, and/or radical species. This work aims at investigating the thermal stability of rare-earth based tetrakis beta-diketonates complexes like M[Eu(dbm)4] (M = Li+, TMPip+, and Morf+) through TG technique coupled with FTIR. Preliminary results show that Li[Eu(dbm)4]·4H2O complex presents no degradation in its structure until 300 °C. However, evidences of rapid thermal degradation of the other two compounds have been found at temperatures lower than 100 °C, implying that these complexes could be degraded during the thermal deposition process at relatively high temperatures.