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| 2. |
- Larsson, L, et al.
(författare)
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Oxidation of Pyrite by Acidianus brierleyi: Importance of Physical Contact Between the Pyrite and the Microorganisms
- 1993
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Ingår i: Biotechnology Letters. - 1573-6776. ; 15:1, s. 99-104
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Tidskriftsartikel (refereegranskat)abstract
- Experiments were done in order to study the thermophilic archaebacterium Acidianus brierleyi during oxidation of pyrite (FeS2). The microorganisms were grown both separated from the pyrite by a membrane and in close contact with the pyrite. From the results it can be concluded that direct contact is needed for good growth of the strain studied. The obtained results indicated that the direct contact mechanism may be applied to oxidation of sulfidic minerals by A. brierleyi.
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| 3. |
- Olsson, G, et al.
(författare)
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Desulfurization of Low Sulfur Coal by it Acidianus brierleyi: Effects of Microbial Treatment on the Properties of Coal
- 1993
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Ingår i: Fuel Processing Technology. - : Elsevier BV. - 0378-3820. ; 33:2, s. 83-93
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Tidskriftsartikel (refereegranskat)abstract
- The effect of microbial desulfurization of two different low-sulfur coals by the thermophilic archaebacteria Acidianus brierleyi was studied with respect to the following properties of the coal: porosity, surface area, pore diameter, particle size, heating value, proximate and ultimate analyses as well as ash composition. About 35-40 percent of the sulfur was oxidized microbially. The microbial treatment only had a slight or negligible effect on most properties. Significant increases were seen with respect to oxygen content and volatile matter for one of the coals. The ash content had a significant increase in phosphorus which originated from the growth medium. Furthermore, jarosite formation was significant, especially for one of the coals investigated. For the same coal a large increase in porosity was seen and the surface area decreased significantly at the same time.
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| 4. |
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| 5. |
- Olsson, U, et al.
(författare)
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Effects of selenium deficiency on xenobiotic-metabolizing and other enzymes in rat liver.
- 1993
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Ingår i: International Journal for Vitamin and Nutrition Research. - 0300-9831 .- 1664-2821. ; 63:1
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Tidskriftsartikel (refereegranskat)abstract
- The present study was undertaken to characterize effects of selenium (Se) deficiency on 16 enzymes recovered in either one or more of the subcellular fractions of rat liver (as a basis for future studies on the mechanisms underlying the observed changes). Male rats were fed a Torula-yeast based diet with 0.23 mg Se/kg or the same diet with 0.009 mg Se/kg, from weaning and for 10 weeks. Statistically significant effects of Se deficiency were the following: Se-dependent glutathione peroxidase decreased to 0.14% of the Se-adequate controls, while cytosolic glutathione transferase increased 3-fold in Se deficiency when CDNB was the substrate, but decreased significantly when trans-stilbene oxide (diagnostic for subunit 4) was used as the substrate. Cytosolic DT-diaphorase increased about 7-fold in Se deficiency. Further, DT-diaphorase in the microsomal fraction was also significantly increased in Se deficiency, as were the microsomal and mitochondrial epoxide hydrolases and microsomal glutathione transferase. Furthermore, increased activity of the peroxisomal marker enzyme catalase (P < 0.05) was noted in Se-deficient rats. It is our working hypothesis that changes in enzyme activities in Se deficiency are mainly due to changed levels of endogenously generated metabolites or altered functions of endocrine tissues.
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| 6. |
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| 7. |
- Wohlfart, B., et al.
(författare)
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Problems of AMS dating the Swedish varved clays of the last glacial-interglacial transition and the potential and difficulties of calibrating Late Weichselian "absolute" chronologies.
- 1993
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Ingår i: Boreas. - : Wiley. - 0300-9483 .- 1502-3885. ; 22:2, s. 113-128
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Tidskriftsartikel (refereegranskat)abstract
- The increasing focus on the chronology of environmental and climatic changes of the last glacial-interglacial transition has led to several independent attempts to try to calibrate the 14C time-scale beyond the Holocene. The Late Weichselian Gotiglacial varved clays of the Swedish Time Scale could potentially be used for this purpose. The reliability of the Swedish Time Scale is discussed as well as different ways of using the Swedish varved clays for calibrating the 14C chronology. The strategy and initial results from an ongoing calibration project are presented. They show clearly that, if the right strategy is adopted, varved clay may be dated by accelerator mass spectrometry (AMS) 14C measurement of terrestrial macrofossils. A Late Weichselian 'event stratigraphy', including the Vedde Ash fall-out, is established for south Scandinavia using three dating categories: clay varve measurements, terrestrial macrofossil measurement, and lake sediment (including aquatic mosses) measurements. It suggests that a 14C chronology based on terrestrial organic remains is not consistent with the traditional Late Weichselian chronostratigraphy based on lake-sediment samples, and that 'clay varve years' exceed 'terrestrial 14C years' by c. 900 years at the end of, and by 1100–1200 years at the beginning of the Younger Dryas Chronozone. Further back in time, the time-scales appear to converge. These results are compared with other recently published calibration studies.
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