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| 2. |
- Blad, Börje, et al.
(författare)
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Improvements in The Hardware of The Lund Impedance Tomography System
- 1992
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Ingår i: Clinical Physics and Physiological Measurement. - 0143-0815. ; 13, s. 15-17
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study is to improve the quality of the hardware of the existing Lund impedance tomography system. Improvement in the current generator and different isolation proposals are presented.
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| 3. |
- Bugaytsova, Zhanna, et al.
(författare)
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Localization, purification and properties of a tetrathionate hydrolase from Acidithiobacillus caldus
- 2004
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Ingår i: European Journal of Biochemistry. - Hoboken : Wiley-Blackwell. - 0014-2956 .- 1432-1033. ; 271:2, s. 272-280
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Tidskriftsartikel (refereegranskat)abstract
- The moderately thermophilic bacterium Acidithiobacillus caldus is found in bacterial populations in many bioleaching operations throughout the world. This bacterium oxidizes elemental sulfur and other reduced inorganic sulfur compounds as the sole source of energy. The purpose of this study was to purify and characterize the tetrathionate hydrolase of A. caldus. The enzyme was purified 16.7-fold by one step chromatography using a SP Sepharose column. The purified enzyme resolved into a single band in 10% polyacrylamide gel, both under denaturing and native conditions. Its homogeneity was confirmed by N-terminal amino acid sequencing. Tetrathionate hydrolase was shown to be a homodimer with a molecular mass of 103 kDa (composed from two 52 kDa monomers). The purified enzyme had optimum activity at pH 3.0 and 40 degreesC and an isoelectric point of 9.8. The periplasmic localization of the enzyme was determined by differential fractionation of A. caldus cells. Detected products of the tetrathionate hydrolase reaction were thiosulfate and pentathionate as confirmed by RP-HPLC analysis. The activity of the purified enzyme was drastically enhanced by divalent metal ions.
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| 4. |
- Dahrén, Börje, fil.dr, 1984-, et al.
(författare)
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Transformation or consolidation : Evaluating transformative agreements at Uppsala University with an eye to the future
- 2021
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Konferensbidrag (refereegranskat)abstract
- In the last few years, we have seen how publishing agreements have become increasingly common across Europe. At Uppsala University, the traditional subscription agreements now represent a minority of our agreements with the publishers and we suspect they will be phased out. Currently, our most common type of publishing agreements are the transformative agreements negotiated on the national level by the Bibsam consortia and offered to all Swedish higher education institutions. These transformative agreements currently cover most major international publishers and could be considered the new normal.Uppsala University is one of the largest and oldest universities in northern Europe. We are a truly multidisciplinary university, covering the humanities, social sciences, medicine, science and technology. This means that the university library should ideally be able to provide the same level of publishing support for theologists as well as geologists. With that in mind, the library was tasked to evaluate our portfolio of publishing agreements, with a special focus on the impact of the transformative ones. We wanted specifically to look at these new agreements in regards to 1) the impact for the individual researchers 2) economic aspects on various levels, and 3) the paradigm shift towards open science that is taking place in scholarly communication.–We have identified a few key effects and aspects of the transformative agreements:• They remove thresholds and provide a smooth transition to OA publishing• They are arguably very expensive. Are these just the latest iteration of the “Big Deals”?• The coverage is not equal for all parts of the university. Great coverage for STEM, not so much for the arts and humanities.• Other publishing actors are unfairly and disproportionally disadvantaged. Non-commercial OA publishers, diamond OA and small scale society publishing lose much of their advantage on the already dysfunctional publishing market.–What to do next?• A local strategy for publishing agreements is needed to complement what is provided by national consortia.• Libraries should divert more energy towards support for DIY publishing and other researcher-led initiatives.• The time for OA advocacy is in the past. It is time for global and holistic open science perspectives.In conclusion, our view is that transformative agreements are highly useful for us at this point in time, but need to be managed and complemented. It is essential that we keep monitoring the costs, provide alternatives and develop our services portfolio. Above all, we need to recognise that these agreements are a stepping stone on the path towards open science. They are, however, not the final solution.
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| 5. |
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| 6. |
- Dopson, Mark, et al.
(författare)
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ATP generation during reduced inorganic sulfur compound oxidation by Acidithiobacillus caldus is exclusively due to electron transport phosphorylation.
- 2002
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Ingår i: Extremophiles. - : Springer Science and Business Media LLC. - 1431-0651 .- 1433-4909. ; 6:2, s. 123-129
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Tidskriftsartikel (refereegranskat)abstract
- The synthesis of adenosine 5-triphosphate (ATP) (increase in phosphorylation potential) during the oxidation of reduced inorganic sulfur compounds was studied in the moderately thermophilic acidophileAcidithiobacillus caldus (strain KU) (formerly Thiohacillus caldus). The phosphorylation potential increased during the oxidation of all reduced inorganic sulfur compounds tested compared with resting cells. The generation of ATP in whole cells was inhibited by the F0F1 ATPase inhibitor oligomycin, electron transport chain inhibitors, valinomycin and potassium ions. There was no increase in the phosphorylation potential, nor synthesis of ATP. in the absence of electron transport. An apparent lack of substrate-level phosphorylation was indicated by the lack of adenosine 5-phosphosulfate reductase in tetrathionate-grown At. caldus. Studies were also performed on the synthesis of ATP by membrane vesicles of At. caldus when presented with an artificial proton gradient. Complete inhibition of ATP synthesis in these vesicles occurred when they were loaded with N,N-dicyclohexylcarbodiimide (DCCD), but not when they were loaded with oligomycin, vanadate or electron transport chain inhibitors. The data presented here suggest that during the oxidation of reduced inorganic sulfur compounds by At. caldus, all ATP is synthesized by oxidative phosphorylation via a membrane-bound F0F1 ATPase driven by a proton gradient.
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| 7. |
- Dopson, Mark, et al.
(författare)
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Mineral and iron oxidation at low temperatures by pure and mixed cultures of acidophilic microorganisms.
- 2007
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Ingår i: Biotechnol Bioeng. - : Wiley. - 0006-3592 .- 1097-0290. ; 97:5, s. 1205-15
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Tidskriftsartikel (refereegranskat)abstract
- An enrichment culture from a boreal sulfide mine environment containing a low-grade polymetallic ore was tested in column bioreactors for simulation of low temperature heap leaching. PCR-denaturing gradient gel electrophoresis and 16S rRNA gene sequencing revealed the enrichment culture contained an Acidithiobacillus ferrooxidans strain with high 16S rRNA gene similarity to the psychrotolerant strain SS3 and a mesophilic Leptospirillum ferrooxidans strain. As the mixed culture contained a strain that was within a clade with SS3, we used the SS3 pure culture to compare leaching rates with the At. ferrooxidans type strain in stirred tank reactors for mineral sulfide dissolution at various temperatures. The psychrotolerant strain SS3 catalyzed pyrite, pyrite/arsenopyrite, and chalcopyrite concentrate leaching. The rates were lower at 5 degrees C than at 30 degrees C, despite that all the available iron was in the oxidized form in the presence of At. ferrooxidans SS3. This suggests that although efficient At. ferrooxidans SS3 mediated biological oxidation of ferrous iron occurred, chemical oxidation of the sulfide minerals by ferric iron was rate limiting. In the column reactors, the leaching rates were much less affected by low temperatures than in the stirred tank reactors. A factor for the relatively high rates of mineral oxidation at 7 degrees C is that ferric iron remained in the soluble phase whereas, at 21 degrees C the ferric iron precipitated. Temperature gradient analysis of ferrous iron oxidation by this enrichment culture demonstrated two temperature optima for ferrous iron oxidation and that the mixed culture was capable of ferrous iron oxidation at 5 degrees C. (c) 2006 Wiley Periodicals, Inc.
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| 8. |
- Dopson, Mark, et al.
(författare)
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Toxicity of metal extraction and flotation chemicals to Sulfolobus metallicus and chalcopyrite bioleaching
- 2006
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Ingår i: Hydrometallurgy. - : Elsevier BV. - 0304-386X .- 1879-1158. ; 81:3-4, s. 205-213
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Tidskriftsartikel (refereegranskat)abstract
- The effect of chemicals used in preparation of mineral concentrates and subsequent extraction of metals to the thermophilic, acidophilic microorganism Sulfolobus metallicus has been tested. The chemicals tested included collectors and frothers employed during flotation of the oreto produce a mineral concentrate, solvent extraction reagents used to remove metals after leaching, and thiocyanate produced as a decomposition product during cyanidation for gold recovery. The effect of these chemicals to S. metallicus depends on the conditions and time frame that the experiments were carried out due to their mode of toxicity and stability in acid pH. The metal extraction chemical that had the least effect on bioleaching was potassium amyl xanthate that increased the leaching rate, possibly due to solubilization of sulfur that can form passivation layers on the surface of minerals. The frother Flotanol C-7 decreased the chalcopyrite leaching rate, despite having no effect on Fe2+ oxidation by S. metallicus resting cells. This is probably due to inhibition of oxygen transfer during bioleaching that had little effect on Fe2+ oxidation over 20 min. Solvent extraction chemicals inhibited both Fe2+ oxidation and bioleaching suggesting their mode of inhibition is due toFe2+ oxidation. The results suggest that relevant concentrations of metal extraction and flotation chemicals can be toxic to chalcopyritebioleaching by S. metallicus.
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| 9. |
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| 10. |
- Dunér, Fredrik, et al.
(författare)
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Permeability, ultrastructural changes, and distribution of novel proteins in the glomerular barrier in early puromycin aminonucleoside nephrosis.
- 2010
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Ingår i: Nephron. Experimental nephrology. - : S. Karger AG. - 1660-2129. ; 116:2
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND/AIMS: It is still unclear what happens in the glomerulus when proteinuria starts. Using puromycin aminonucleoside nephrosis (PAN) rats, we studied early ultrastructural and permeability changes in relation to the expression of the podocyte-associated molecules nephrin, α-actinin, dendrin, and plekhh2, the last two of which were only recently discovered in podocytes. METHODS: Using immune stainings, semiquantitative measurement was performed under the electron microscope. Permeability was assessed using isolated kidney perfusion with tracers. Possible effects of ACE inhibition were tested. RESULTS: By day 2, some patchy foot process effacement, but no proteinuria, appeared. The amount of nephrin was reduced in both diseased and normal areas. The other proteins showed few changes, which were limited to diseased areas. By day 4, foot process effacement was complete and proteinuria appeared in parallel with signs of size barrier damage. Nephrin decreased further, while dendrin and plekhh2 also decreased but α-actinin remained unchanged. ACE inhibition had no significant protective effect. CONCLUSIONS: PAN glomeruli already showed significant pathology by day 4, despite relatively mild proteinuria. This was preceded by altered nephrin expression, supporting its pivotal role in podocyte morphology. The novel proteins dendrin and plekhh2 were both reduced, suggesting roles in PAN, whereas α-actinin was unchanged.
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