| 1. |
- Rizzi, Maria C., 1987-, et al.
(författare)
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Snabbcykelstråk i planeringen och praktiken : erfarenheter från Sverige, Norge och Danmark
- 2022
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Syftet med studien har varit att ge en övergripande bild av vilka utmaningar, kunskapsluckor och behov som transportaktörer i Sverige, Norge och Danmark möter i hanteringen av snabbcykelstråk. Fokus har varit på hur tjänstemän från dessa tre länder med ansvar eller engagemang i snabbcykelstråk upplever planering, utformning, drift och underhåll samt utvärdering av stråken. I rapporten lyfts områden där det upplevs saknas stöd eller kunskap, samt likheter och skillnader mellan länderna.En webbenkät med efterföljande intervjuer har använts som datainsamlingsmetod. Webbenkäten sändes till 40 personer i Sverige, Norge och Danmark som på olika sätt arbetar med snabbcykelstråk. Svar inkom från 25 personer. Av dessa valdes sju personer ut för att genomföra en efterföljande intervju.Förutsättningarna att arbeta med snabbcykelstråk skiljer sig mellan länderna, till exempel med hänsyn till väghållaransvar och finansieringsmöjligheter, men även inom länderna kan förutsättningar skilja sig. Det tycks finnas ett behov av nationell samordning kring snabbcykelstråk, samtidigt som man inte ville se några ”tvingande regler” kring utformning. I Sverige efterlyser man särskilt en samordning kring skyltning av snabbcykelstråk, något som redan finns i Danmark. Det upplevdes svårare att planera för snabbcykelstråk jämfört med annan cykelinfrastruktur och det finns aspekter av snabbcykelstråk som skiljer sig från annan cykelinfrastruktur, som till exempel högre krav på utformning, underhåll och säkerhet, samt högre krav på samarbete och samordning. Utvärdering av snabbcykelstråken är något man arbetar med lokalt, och det finns ingen sammanställd systematisk kunskap kring de modeller eller metoder som används för utvärdering. Informationsutbyte mellan olika aktörer i Sverige, Norge och Danmark skulle kunna öka kunskapen och ge nya infallsvinklar hur planering och genomförande av snabbcykelvägar kan förbättras.
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| 2. |
- Filipsson, Magnus, et al.
(författare)
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Efterbehandling av gruvavfall med morän/grönlutslam i tätskiktskonstruktionen : Massor med fördelar
- 2015
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Ingår i: Bygg och Teknik. - 0281-658X .- 2002-8350. ; :1, s. 66-70
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Dagens praxis för täckning av sulfidhaltiga gråbergsrester är att täcka med morän. Det görs som ”kvalificerad täckning” genom att lägga på ett tätskikt med lerig morän som packas tätt. I ett önskescenario finns siltig/lerig morän i anslutning till området som är tillräckligt tätt och som kan användas för att anlägga tätskikt. Erfarenhet visar dock att täta moräner förekommer sällan i gruvans närområde och funktionen som syrebarriär inte alltid uppfylls av lokalt förekommande morän. Alternativet är att använda andra tätskiktsmaterial, bentonitmatta, lera etcetera eller att modifiera lokalt förekommande morän. Ett alternativ är att modifiera lokalt förekommande morän genom inblandning av grönlutslam. Grönlutslammet har stor vattenhållande förmåga och en inblandning på cirka tio procent grönlutslam i siktad morän förbättrar moränens funktion som tätskikt avsevärt.Ett vanligt sätt att efterbehandla gruvavfall är att täcka det med ett skikt som hindrar syret att nå avfallet och därmed hindra oxidationen, även kallad kvalificerad täckning. Huvudfunktionkskravet är att minimera syretransporten och främst syrediffusionen över tid, vilket innebär i praktiken att tätskiktets hydrauliska konduktivitet ska vara under 10-8 m/s. I ett önskescenario finns siltig/lerig morän i anslutning till området som är tillräckligt tätt och som kan användas för att anlägga dessa skikt.
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| 3. |
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| 4. |
- Ikumapayi, Fatai, et al.
(författare)
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Recycling of process water in sulphide flotation : Effect of calcium and sulphate ions on flotation of galena
- 2011
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Ingår i: 5th International Flotation Conference 2011. - Red Hook : Curran Associates, Inc.. - 9781618393951 ; , s. 222-249
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Konferensbidrag (refereegranskat)abstract
- The effects of major components of calcium and sulphate species present in recycled process water on galena flotation has been investigated through Hallimond flotation, zeta-potential, diffuse reflectance FTIR spectroscopy and XPS measurements using pure galena mineral as well as bench scale flotation tests using complex sulphide ore. The significance of process water species in flotation has been assessed using deionised water, process water and simulated water containing calcium and sulphate ions in experiments. In addition, the effect of temperature in bench scale flotation tests has also been examined.Hallimond flotation indicated lower recoveries of galena in the presence of calcium and sulphate ions using potassium amyl xanthate as collector. Calcium ions increase zeta-potential of galena while sulphate ions have no effect. FTIR and XPS studies revealed the presence of surface oxidised sulfoxy, hydroxyl and carbonate species on galena at pH 10.5 in deionised and process water, which surface species affected xanthate adsorption. Bench scale flotation using two different complex sulphide ores showed that galena recovery is better in process water than tap water at room temperature. Flotation results also indicated decrease of galenarecovery at temperatures lower than 22oC in either tap water or process water.
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| 5. |
- Ikumapayi, Fatai, et al.
(författare)
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Recycling of process water in sulphide flotation : effect of calcium and sulphate ions on flotation of galena
- 2012
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Ingår i: Minerals Engineering. - : Elsevier BV. - 0892-6875 .- 1872-9444. ; 39, s. 77-88
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Tidskriftsartikel (refereegranskat)abstract
- The effects of major components of calcium and sulphate species present in recycled process water on galena flotation has been investigated through Hallimond flotation, zeta-potential, diffuse reflectance FTIR spectroscopy and XPS measurements using pure galena mineral. The significance of process water species in flotation has been understood using deionised water, process water and simulated tap water containing equivalent calcium and sulphate ions concentration as in process water.Hallimond flotation indicated marginally lower recoveries of galena in the presence of calcium and sulphate ions using potassium amyl xanthate as collector. Zeta-potential shows the adsorption of calcium ions whereby the potential are seen to increase while sulphate ions have no significant effect. FTIR and XPS studies revealed surface calcium carbonate and/or calcium sulphate species in process water which affected xanthate adsorption. Presence of surface oxidised species such as sulfoxy, hydroxyl species on galena at pH 10.5 in deionised and process water was also revealed.
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| 6. |
- Ikumapayi, Fatai, et al.
(författare)
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Recycling process water in complex sulphide ore flotation
- 2012
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Ingår i: XXVI International Mineral Processing Congress (IMPC) 2012. - New Dehli : The Indian Institute of Metals. - 9788190171434 ; , s. 4411-4425
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Konferensbidrag (refereegranskat)abstract
- An approach to environmental sustainability and improved process economy, in sulphide minerals production is recycling of process water in flotation of complex sulphide ores, although the chemistry of process water may be a critical issue to flotation efficiency. The influence of major components of calcium and sulphate ions in process water on xanthate collector adsorption and flotation response using pure chalcopyrite, galena and sphalerite minerals were investigated by Hallimond flotation, zeta-potential measurement, FTIR and XPS spectroscopy studies, while bench scale flotation tests were also carried out using complex sulphide ores. The impact of the species in flotation was comprehended using deionised water, tap water, process water and simulated water containing equivalent amount of calcium and sulphate species in process water. Hallimond flotation results showed a decrease of chalcopyrite and galena recovery in process water and also in the presence of calcium and sulphate ions in both deionised and process waters, whereas sphalerite does not respond to flotation. The adsorption of calcium and metal ions but not sulphate ions on the minerals is evidenced by zeta-potential data. FTIR and XPS studies revealed the presence of surface oxidized sulfoxy species and surface calcium carbonates on chalcopyrite in the presence of process water and water containing calcium ions, surface oxidized sulfoxy and carbonate species on galena in the presence of deionised water, process water and water containing calcium and sulphate ions, all at flotation pH 10.5, and these surface species influenced xanthate adsorption. The presence of surface oxidized sulfoxy and carbonate species at the sphalerite flotation pH 11.5 were seen in the presence of deionised water, process water and water containing calcium and sulphate ions, but the surface species does not influence xanthate adsorption. Bench scale flotation using two different complex sulphide ores showed that chalcopyrite, galena and sphalerite recoveries are better in process water than tap water. The studies showed that the process water can be recycled in flotation with no detrimental effect on grade and recovery of sulphide minerals.
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| 7. |
- Ikumapayi, Fatai, et al.
(författare)
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Recycling process water in sulfide flotation, Part A: Effect of calcium and sulfate on sphalerite recovery
- 2012
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Ingår i: Minerals & metallurgical processing. - : Springer Science and Business Media LLC. - 0747-9182. ; 29:4, s. 183-191
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Tidskriftsartikel (refereegranskat)abstract
- In order to predict and minimize detrimental production problems due to the recycling of process water in sulfide ore processing, the influence of major species, calcium and sulfate in process water on sphalerite flotation was investigated through Hallimond tube flotation, zeta potential, diffuse reflectance Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) measurements using sphalerite mineral sample. Assessment of process water species in flotation was done using deionized water, process water and simulated water containing calcium and sulfate ions in experiments. Hallimond flotation shows increased sphalerite floatability in process water compared to deionized water, but no significant effect on the presence of calcium and sulfate ions in deionized water using isobutyl xanthate as a collector. The presence of calcium ions reduced the sphalerite's negative zeta potential, while at higher concentrations, a charge reversal occurred, at about pH 11. FTIR and XPS studies revealed the presence of surface-oxidized sulfoxy and carbonate species on sphalerite at pH 11.5 in deionized water, process water and water containing calcium and sulfate ions. These surface species do not influence xanthate adsorption.
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| 8. |
- Jia, Yu, et al.
(författare)
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Elemental mobility in sulfidic mine tailings reclaimed with paper mill by-products as sealing materials
- 2017
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Ingår i: Environmental Science and Pollution Research. - : Springer. - 0944-1344 .- 1614-7499. ; 24:25, s. 20372-20389
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Tidskriftsartikel (refereegranskat)abstract
- Sealing layers made of two alkaline paper mill by-products, fly ash and green liquor dregs, were placed on top of 50-year-old sulfide-containing tailings as a full-scale remediation approach. The performance and effectiveness of the sealing layers with high water content for an oxygen barrier and low hydraulic conductivity for a sealing layer in preventing the formation of acid rock drainage were evaluated 5 years after the remediation. The leaching behavior of the covered tailings was studied using batch leaching tests (L/S ratio 10 L/kg). The leaching results revealed that, in general, the dregs- and ash-covered tailings released relatively lower concentrations of many elements contained in acid rock drainage compared to those from the uncovered tailings. A change in the chemical composition and mineralogical state of the tailings was observed for the tailings beneath the covers. The increase in pH caused by the alkaline materials promoted metal precipitation. Geochemical modeling using PHREEQC confirmed most of the geochemical changes of the covered tailings. Both the ash and dregs showed potential to function as sealing materials in terms of their geochemical properties. However, mobilization of Zn and Ni from the lower part of the dregs-covered tailings was observed. The same phenomenon was observed for the lower part of the ash-covered tailings. Ash showed advantages over dregs as a cover material; based on geochemical studies, the ash immobilized more elements than the dregs did. Lysimeters were installed below the sealing layers, and infiltrating water chemistry and hydrology were studied to monitor the amount and quality of the leachate percolating through.
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| 9. |
- Jia, Yu, et al.
(författare)
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Use of amended tailings as mine waste cover
- 2013
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Ingår i: Waste and Biomass Valorization. - : Springer Science and Business Media LLC. - 1877-2641 .- 1877-265X. ; 4:4, s. 709-718
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Tidskriftsartikel (refereegranskat)abstract
- The present study addresses the effectiveness of green liquor dregs (GLD, a residue from paper pulp-making) as a paste additive with different proportions in tailings for stabilizing mine waste by testing of uniaxial compressive strength and hydraulic conductivity. Selected samples were also investigated for freeze–thaw effect on hydraulic conductivity, and the water retention capacity was discussed based on previous results. Fly ash was also added to the paste to study the auxiliary functions such as solidification in the sealing material. GLD have the potential for use as a barrier layer material for stabilizing mine tailings by decreasing water percolation and improving water retention properties. However, the solidified paste of GLD-amended tailings possesses low uniaxial compressive strength, but the addition of fly ash to the paste increased the uniaxial compressive strength by up to 2–3 times 1 month after it was solidified, with a further two- to threefold strength increase after 3-months curing time. Although the hydraulic conductivity of the tailings paste decreased as a consequence of mixing with both GLD and FA, the difference was within one order of magnitude. The hydraulic conductivity was also reduced as the water/solid ratio of pure GLD decreased. The climatic freeze–thaw cyclic process led to 20 % increase in hydraulic conductivity. A proportion of 7:2:1 for tailings:GLD:FA was found to be a geotechnical satisfactory recipe to seal the mine waste. If porosity is reduced, improved water retention capacity and no cracking in the tailings can be assured, oxygen diffusion is limited, and oxidation of the mine waste is decelerated, thus mitigating acid rock drainage.
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| 10. |
- Jia, Yu, et al.
(författare)
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Use of rest products as additive in tailings paste for the mitigation of ARD : Effect of green liquor dregs and fly ash addition on geotechnical stabilization of tailings
- 2012
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Ingår i: Proceedings of the 8th International Conference on the Environmental and Technical Implications of Construction with Alternative Materials. - : ISCOWA.
-
Konferensbidrag (refereegranskat)abstract
- This study focuses on the effect of green liquor dregs (GLD) and fly ash (FA) on geotechnical stabilization of tailings, using shear strength test.The objectives were to evaluate thickening of tailings using GLD to paste to improve its water retention and to reduce waste percolation, to identify optimal proportion of additives regarding geotechnical stabilization of tailings, and to study the role of FA in the decrease of porosity and thus to reduce oxygen diffusion via hardening process.The results showed that GLD is a potential material for tailings stabilization by decreasing water percolation and improving water retention property. However, the paste of GLD amended tailings withstands low shear strength. The addition of FA to the paste greatly improves shear strength which is up to 2-3 times higher. Moreover, the fly ash hardening process effectively reinforces the strength of GLD amended tailings paste. Longer curing period (3 months) for specimens leads to up to 2-3 folds higher strength compared to that of 1 month. Hydraulic conductivity is reduced as a result of GLD and FA addition, since the porosity of the tailings decreased. If reduced porosity, improved water retention capacity and no cracks are ensured in the tailings, oxygen diffusion can be limited.
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| 11. |
- Jia, Yu, et al.
(författare)
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Variation of green liquor dregs from different pulp and paper mills for use in mine waste remediation
- 2019
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Ingår i: Environmental Science and Pollution Research. - : Springer. - 0944-1344 .- 1614-7499. ; 26:30, s. 31284-31300
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Tidskriftsartikel (refereegranskat)abstract
- The geotechnical, chemical, and mineralogical properties of green liquor dregs (GLDs) generated as byproducts from five paper mills were investigated to assess their buffering and heavy metal immobilization capacities and their roles as water and oxygen barriers. One type of GLD was further studied to test the effects of the retrieval process and the storage, drying, and hydration of GLD. The high water retention capacity of the GLDs is valuable for limiting O2diffusion. Laboratory results showed that the GLDs had hydraulic conductivities of 3.7 × 10−9–4.6 × 10−8 m/s and varied regularly in plasticity. The chemical and mineralogical compositions of the GLDs varied greatly, reflecting the raw material used to produce paper and the process used to retrieve GLDs. Although they had high total heavy metal contents, none of the leached elements from the GLDs (L/S 10 cm3/kg) exceeded the European Union’s limits for landfills of non-hazardous waste. The GLDs exhibited high buffering capacities. In a supplementary test, the buffering capacities varied (0.0041–0.0114 M H+/g GLD) over 72 d after acid was added to the GLD. Changing the filtration process did not greatly affect the GLDs’ properties but mainly affected the hydraulic conductivity, total heavy metal contents and sulfur content. Analyzing the storage of GLDs is necessary in the mining industry because remediation measures require large amounts of material over short periods. The buffering capacity of the dried GLD decreased slightly. The effect of dewatering caused by the mixing of 2% Na-lignosulfate with GLD (w/w) was low.
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| 12. |
- Larsson, Jan, et al.
(författare)
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“Painting of Fourth” in different evolutionary lineages of Drosophila suggests chromosome specific gene regulation
- 2004
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 101:26, s. 9728-9733
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Tidskriftsartikel (refereegranskat)abstract
- Painting of fourth (POF) is a chromosome-specific protein in Drosophila and represents the first example of an autosome-specific protein. POF binds to chromosome 4 in Drosophila melanogaster, initiating at the proximal region, followed by a spreading dependent on chromosome 4-specific sequences or structures. Chromosome-specific gene regulation is known thus far only as a mechanism to equalize the transcriptional activity of the single male X chromosome with that of the two female X chromosomes. In Drosophila, a complex including the male-specific lethal proteins, "paints" the male X chromosome, mediating its hypertranscription, explained to some extent by the acetylation of lysine 16 on histone H4. Here, we show that Pof is essential for viability in both sexes and for female fertility. POF binding to an autosome, the F element, is conserved in genus Drosophila, indicating functional conservation of the autosome specificity. In three of nine studied species, POF binds to the male X chromosome. When bound to the male X, it also colocalizes with the dosage compensation protein male-specific lethal 3, suggesting a relationship to dosage compensation. The chromosome specificity is determined at the species level and not by the amino acid sequence. We argue that POF is involved in a chromosome-specific regulatory function
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| 13. |
- Larsson, Jan, et al.
(författare)
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Painting of fourth in genus Drosophila suggests autosome-specific gene regulation
- 2004
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - Washington : National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 101:26, s. 9728-9733
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Tidskriftsartikel (refereegranskat)abstract
- Painting of fourth (POF) is a chromosome-specific protein in Drosophila and represents the first example of an autosome-specific protein. POF binds to chromosome 4 in Drosophila melanogaster, initiating at the proximal region, followed by a spreading dependent on chromosome 4-specific sequences or structures. Chromosome-specific gene regulation is known thus far only as a mechanism to equalize the transcriptional activity of the single male X chromosome with that of the two female X chromosomes. In Drosophila, a complex including the male-specific lethal proteins, "paints" the male X chromosome, mediating its hypertranscription, explained to some extent by the acetylation of lysine 16 on histone H4. Here, we show that Pof is essential for viability in both sexes and for female fertility. POF binding to an autosome, the F element, is conserved in genus Drosophila, indicating functional conservation of the autosome specificity. In three of nine studied species, POF binds to the male X chromosome. When bound to the male X, it also colocalizes with the dosage compensation protein male-specific lethal 3, suggesting a relationship to dosage compensation. The chromosome specificity is determined at the species level and not by the amino acid sequence. We argue that POF is involved in a chromosome-specific regulatory function.
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| 14. |
- Löfgren, Kent, 1966-, et al.
(författare)
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Meeting the Challenges of Generational Change in the Teaching Profession : Towards a European Model for Intergenerational Teacher Collaboration
- 2013
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Ingår i: Educational Research eJournal. - : Educational Research e-Journal (EREJ). - 2254-0385. ; 2:2, s. 107-119
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Tidskriftsartikel (refereegranskat)abstract
- In a European-wide effort to improve the professional development of teachers, the 2AgePro project was conducted from November 2008 to October 2010. One of its goals was to develop and test different forms of intergenerational teacher collaboration among junior and senior teachers in primary and secondary schools. Another aim was to utilise the results from these pilots, which were conducted in the Czech Republic, Finland, Germany, the Netherlands, and Sweden, to create a model for intergenerational collaboration that could be used in any national or cultural setting. This article reports on the national pilots and proposes a European model for intergenerational collaboration for teachers.
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| 15. |
- Maurice, Christian, et al.
(författare)
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Green liquor dregs for the amendment of tailings
- 2010
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Ingår i: Paste 2010. - Nedlands, WA : Australian Centre for Geomechanics. - 9780980615401 ; , s. 487-494
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Konferensbidrag (refereegranskat)abstract
- Green liquor dregs (GLD) from the sulphate pulping process is one of the main wastes from the pulp industry still being landfilled in Sweden. GLD has similar hydro-geotechnical properties as tailings paste and may be used as an amendment to tailings to reduce the leachate generation, improve the leachate quality, and improve the geotechnical properties of the mixture. The addition of 10% GLD (dry weight basis) reduced the hydraulic conductivity of the tailings by a factor of two. Addition of a 30% mixture (on a dry weight basis) of GLD and fly ash (FA) to tailings reduced the hydraulic conductivity by more than one order of magnitude. Thanks to its alkaline properties and it negative zeta potential, GLD has a direct effect on the metal leaching from tailings. The alkaline capacity of the pulping wastes raised the pH in the stabilized tailings and reduced leaching of Cu, Co, Cd, and Ni. Addition of 10% pulping waste to tailings on a dry weight basis was sufficient to reduce copper leaching by a factor of 4 to 10.
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| 16. |
- McCrann, Donald J., et al.
(författare)
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Differential expression of NADPH oxidases in megakaryocytes and their role in polyploidy
- 2009
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Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 114:6, s. 1243-1249
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Tidskriftsartikel (refereegranskat)abstract
- Megakaryocytes (MKs) undergo an endomitotic cell cycle, leading to polyploidy. We examined the expression of the flavoproteins and oxidative stress-promoting enzymes, NADPH oxidases (Nox's), in MKs because of their known role in promoting the cell cycle. Although the expression of Nox isoforms varies between cell types, they are induced at the mRNA level by mitogenic stimuli. Western blotting or reverse transcription-polymerase chain reaction of purified mouse MKs isolated from thrombopoietin (TPO)-treated bone marrow (BM) cultures indicated high expression of Nox1, a weak expression of Nox4, and no significant expression of Nox2. Immunofluorescence of freshly isolated MKs confirmed strong expression of Nox1 in one-third of MKs, whereas Nox1 staining was detected in nearly all MKs in TPO-stimulated BM cultures. Treatment of mouse BM cultures with Nox inhibitors resulted in accumulation of MKs with low DNA content levels and significant reduction of higher ploidy MKs. Purified, Nox-inhibited MKs showed a notable decrease in the level of the G1 phase cyclin E, a cyclin associated with MK polyploidy, and its up-regulation restored most of the effect of Nox inhibitors. Hence, this study shows the expression of Nox isoforms in MKs and highlights a potential role of flavoproteins in promoting polyploidization in this lineage
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| 17. |
- Mäkitalo, Maria, et al.
(författare)
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An Evaluation of Using Various Admixtures of Green Liquor Dregs, a Residual Product, as a Sealing Layer on Reactive Mine Tailings
- 2016
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Ingår i: Mine Water and the Environment. - : Springer Science and Business Media LLC. - 1025-9112 .- 1616-1068. ; 35:3, s. 283-293
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Tidskriftsartikel (refereegranskat)abstract
- Green liquor dregs (GLD), a residual product from sulfate paper mills, was blended with tailings, fly ash, and bark sludge with the aim of improving the material’s physical properties so that it could function as a sealing layer in dry covers on sulfidic mine waste. Geotechnical and geochemical investigations, including weathering cell tests, were carried out on GLD with admixtures to assess their effectiveness. Due to its alkaline character, GLD was shown to have the potential to improve leachate quality by decreasing metal mobility when blended with tailings. The admixtures showed favorable sealing layer properties such as high water retention capacity and low hydraulic conductivity. However, caution must be exercised when the dregs are blended with tailings containing large amounts of As and Mo, since increased leaching of these elements may be expected.
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| 18. |
- Mäkitalo, Maria, et al.
(författare)
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Assessment of the effect of aging on green liquor dregs cover for tailings deposits - Field investigation
- 2012
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Ingår i: Proceedings of the 8th WASCON 2012 – towards effective, durable and sustainable production and use of alternative materials in construction.. - : ISCOWA.
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Konferensbidrag (refereegranskat)abstract
- Green liquor dregs (GLD) are the largest waste fraction retrieved at the sulphate pulp mill. GLD has a low hydraulic conductivity and is alkaline which opens the possibility of using it for construction of sealing layers. Two sites have been sampled where the GLD age is known. The effect of aging on the material properties specifically the ability to function as a barrier against oxygen and its capacity to buffer in the long term was studied. The mechanical strength has also been evaluated to asses if it can withstand the pressures from the cover layer. Suction tests showed that the capillarity forces in GLD bind water strongly to the particles preventing it from drying. The high water content in GLD and the strength of the water bounding are major advantages for the use in sealing layers to create a water saturated layer preventing oxygen penetration. GLD is therefore believed to be an excellent barrier material in the sealing layer. The GLD’s buffering capacity is high and the results indicate that it will last for a long time which is consistent with its large reservoir of lime. The shear strength increased when the GLD is placed in field conditions.
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| 19. |
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| 20. |
- Mäkitalo, Maria, et al.
(författare)
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Characterization of Green Liquor Dregs, Potentially Useful for Prevention of the Formation of Acid Rock Drainage
- 2014
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Ingår i: Minerals. - : MDPI AG. - 2075-163X. ; 4:2, s. 330-344
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Tidskriftsartikel (refereegranskat)abstract
- Using alternative materials such as residual products from other industries to mitigate the negative effects of acid rock drainage would simultaneously solve two environmental problems. The main residual product still landfilled by sulphate paper mills is the alkaline material green liquor dregs (GLD). A physical, mineralogical and chemical characterization of four batches of GLD was carried out to evaluate the potential to use it as a sealing layer in the construction of dry covers on sulphide-bearing mine waste. GLD has relatively low hydraulic conductivity (10−8 to 10−9 m/s), a high water retention capacity (WRC) and small particle size. Whilst the chemical and mineralogical composition varied between the different batches, these variations were not reflected in properties such as hydraulic conductivity and WRC. Due to relatively low trace element concentrations, leaching of contaminants from the GLD is not a concern for the environment. However, GLD is a sticky material, difficult to apply on mine waste deposits and the shear strength is insufficient for engineering applications. Therefore, improving the mechanical properties is necessary. In addition, GLD has a high buffering capacity indicating that it could act as an alkaline barrier. Once engineering technicalities have been overcome, the long-term effectiveness of GLD should be studied, especially the effect of aging and how the sealing layer would be engineered in respect to topography and climatic conditions.
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| 21. |
- Mäkitalo, Maria
(författare)
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Green liquor dregs as sealing layer material to cover sulphidic mine waste deposits
- 2012
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Waste rock and tailings generated by sulphide ore mining often contains large amounts of iron sulphides which oxidize when exposed to atmospheric oxygen and may generate acidity. In the absence of alkaline minerals to neutralize this acidity, elements including harmful heavy metals become mobile. Clearly, it is a high priority for mining operations to reduce the impact of mining waste on the environment. New research aimed to take advantage of industrial rest products to inhibit acid mine drainage has yielded some reason for optimism. The recycling of chemicals in sulphate pulp mills yields green liquor dregs (GLD). The fact that GLD have a low hydraulic conductivity and are alkaline opens the possibility of using it for construction of sealing layers for sulphidic mine waste. The study consists of two parts. The aim of the first part was to characterize the GLD and evaluate their suitability for sealing layer purposes. GLD were characterized physically, mineralogically and chemically to define variations in the properties of the material and to evaluate if they can act as a potential candidate for construction of sealing layers. Compared to lime, the pure GLD appear to have a higher porosity and surface area even though both materials have comparable particle size. The shear strength may, however, be insufficient. In cover applications, where high compaction grade and low hydraulic conductivity are desirable, mixing additives to GLD is necessary to improve the material properties. Based on the characterization results, the difference between batches is fairly small both mineralogically and physically. GLD could be an alternative to traditional sealing layers made of till since it was shown to have relatively low hydraulic conductivity and high water retention potential. The small particle size and high buffer capacity makes it a better candidate than till which usually varies in size and hydraulic conductivity. There is a chemical variation of the material but the element content does not seem to be an environmental concern.The aim of the second part of the study was to improve the performance of the GLD by blending them with other rest products. Geotechnical and geochemical investigations were performed on GLD mixed with tailings. Humidity cell tests were used to study the effect of GLD on the mobility of elements considered to be major environmental issues in the tailings. By adding tailings to GLD, the shear strength improved 2-3 times after 1 month of curing. The water retention capacity remained at a high level. Humidity cell tests revealed that a 50/50 mix of GLD and tailings has a direct effect on the metal leaching from tailings. The alkaline capacity of the pulping waste raised the pH, thereby stabilizing the tailings and reducing the leaching of Al, Cd, Cu, Ni, Co, Cr and Mn. The amount of leached elements could be directly related to the pH during the test. Elements that showed an increase of leaching as a result of the application of GLD were Mo and As. This is explained by the chemical behavior of these elements and their tendency to become mobile at high pH.In summary, GLD have the potential to both reduce the amount of leachate generated in tailings and, due to their alkaline property, improve the leachate quality by decreasing the metal mobility. However, restrictions occur when GLD are blended with tailings containing large amounts of As and Mo since an increased leaching may be expected. Further research will focus on the aging of the material and its long-term stability.
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| 22. |
- Mäkitalo, Maria
(författare)
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Green Liquor Dregs in Sealing Layers to Prevent the Formation of Acid Mine drainage : From characterization to implementation
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- One of the mining industry’s main concerns is the management of waste rock and tailings generated by sulfide ore extraction. Upon exposure to atmospheric oxygen, iron sulfides oxidize producing acidity. In the absence of alkaline minerals to neutralize this acidity, elements including harmful heavy metals may be transported with percolated water, forming acid mine drainage (AMD). A common solution to prevent oxygen and water entering sulfide-bearing mine waste, thereby minimizing the formation of AMD, is to construct a dry cover comprised of soil. In Sweden, clayey till is often used. Due to a shortage of fine-grained till close to mines, other sealant materials must be considered. This thesis presents an alternative to the traditional materials used as sealing layers in dry covers. Green liquor dregs (GLD) are a residual waste originating from the recycling of chemicals in sulfate pulp mills. The objective was to evaluate the suitability of GLD for use in sealing layers for sulfidic mine waste. This was carried out by analyzing samples both in the laboratory and in the field in a pilot-scale study. GLD was characterized physically, mineralogically and chemically to determine variations in the properties of the material. Based on the characterization results, the difference between batches was small both mineralogically and physically. In addition, it had favorable qualities with respect to reducing water percolation and oxygen diffusion, as it exhibited low hydraulic conductivity and high water retention potential. However, the shear strength was insufficient for cover applications. In an attempt to improve shear strength, but also to reduce the amount of GLD to save transportation costs, fly ash, tailings and till were blended with GLD. All of these additives increased the shear strength. Humidity cell tests were used to study the effect of GLD on the mobility of elements found in the tailings that are considered to cause major environmental issues. They showed that the alkaline capacity of the GLD raised the pH, thereby stabilizing the tailings and reducing the leaching of Zn, Cd, Cu, Ni, Co and Cr. The amount of leached elements could be directly related to pH. Mo and As leaching increased as a result of the application of GLD. This is explained by the chemical behavior of these elements and their tendency to become mobile at high pH. Because covers on mine waste should be efficient over the long-term, the aging of GLD was studied with material ranging from 0-13 years old. Aged GLD showed a hydraulic conductivity of 10-8 m/s. This is not expected to affect the function of the sealing layer to minimize oxidation because older GLD exhibited a high water retention capacity and a degree of water saturation of >91%, which would effectively limit oxygen diffusion. Leaching, mainly of S and K, was observed but had no major effect on the hydraulic properties of the material. The effects of aging are largely related to the quantity of water passing through the GLD, thereby changing its chemical composition and, in the long term, its pH. An implementation study using GLD as an additive to improve the hydraulic properties of till in the construction of sealing layers in a cover system design was carried out. The results showed that the quality of till, i.e., hydraulic conductivity and water retention capacity, could be improved by the addition of GLD. Addition of 10% GLD was found to be sufficient to take full advantage of its hydraulic properties and sufficient compaction could be achieved. Based on the results, GLD is expected to be a viable alternative to traditional cover materials. The pilot-scale study, as well as a full-scale trial that is currently in progress, will be used to evaluate further the function of a GLD-based sealing layer.
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| 23. |
- Mäkitalo, Maria, et al.
(författare)
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Improving Properties of Sealing Layers Made of Till by Adding Green Liquor Dregs to Reduce Oxidation of Sulfidic Mine Waste
- 2015
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Ingår i: Geotechnical and Geological Engineering. - : Springer Science and Business Media LLC. - 0960-3182 .- 1573-1529. ; 33:4, s. 1047-1054
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Tidskriftsartikel (refereegranskat)abstract
- A common solution to minimize formation of acid rock drainage in sulfide-bearing mine waste is to construct a composite cover comprising till. Due to a shortage of fine-grained till close to mines, other sealant materials must be considered. Here, the feasibility of using green liquor dregs (GLD), an alkaline and inorganic residual waste, as an additive to improve low quality till in the construction of sealing layers in cover system designs was studied. GLD was blended with three types of till in a pilot scale study. 10–15 % (wet weight) GLD was found to be sufficient to take full advantage of the physical properties of the residual waste. Different mixing techniques were also evaluated. The results showed that the quality of till, i.e., hydraulic conductivity and water retention capacity, could be improved by addition of 10 % GLD. Short duration and efficient mixing was preferred as vigorous mixing released water bound in the GLD, resulting in increased w and reduced compaction efficiency, making the blended material difficult to apply and use in sealing layer constructions.
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| 24. |
- Mäkitalo, Maria, et al.
(författare)
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Prediction of the long-term performance of green liquor dregs as a sealing layer to prevent the formation of acid mine drainage
- 2016
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Ingår i: Journal of Environmental Chemical Engineering. - : Elsevier BV. - 2213-3437. ; 4:2, s. 2121-2127
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Tidskriftsartikel (refereegranskat)abstract
- One of the mining industry's main concerns is the management of waste rock and tailings generated by sulfide ore extraction. Upon exposure of atmospheric oxygen, iron sulfides oxidize generating acidity. Infiltrating water form a metal-rich acidic leachate called acid mine drainage (AMD), that can cause serious environmental problems. Green liquor dregs (GLD) is a material that resists the passage of oxygen and water and could thus be used to seal mine wastes, preventing their oxidation and AMD formation. To enable its use in dry mine waste covers, the long-term efficiency of such GLD sealing layers must be evaluated. In this study, fresh GLD and GLD aged for 3 to 13 years was collected from two sites and analysed to determine how aging affects its chemical and physical properties. Aged and fresh GLD were very similar with respect to all the properties important in a sealing layer. In particular, there was no evidence of calcite dissolution in aged GLD samples. Aged GLD also exhibited high water saturation (>91%) and chemical stability, both of which are important for effective long-term sealing. The shear strength of GLD deployed in the field increased over time but not sufficiently to ensure the long-term physical integrity of a pure GLD sealing layer. The development of hybrid materials with improved shear strength will therefore be necessary.
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| 25. |
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| 26. |
- Nguyen, Hao G., et al.
(författare)
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Conditional overexpression of transgenes in megakaryocytes and platelets in vivo
- 2005
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Ingår i: Blood. - : American Society of Hematology. - 0006-4971 .- 1528-0020. ; 106:5, s. 1559-1564
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Tidskriftsartikel (refereegranskat)abstract
- Megakaryocyte (MK)-specific transgene expression has proved valuable in studying thrombotic and hemostatic processes. Constitutive expression of genes, however, could result in altered phenotypes due to compensatory mechanisms or lethality. To circumvent these limitations, we used the tetracycline/doxycycline (Tet)-off system to conditionally over-express genes in megakaryocytes and platelets in vivo. We generated 3 transactivator transgenic lines expressing the Tet transactivator element (tTA), under the control of the MK-specific platelet factor 4 promoter (PF4-tTA-VP16). Responder lines were simultaneously generated, each with a bidirectional minimal cytomegalovirus (CMV)-tTA responsive promoter driving prokaryotic β-galactosidase gene, as a cellular reporter, and a gene of interest (in this case, the mitotic regulator Aurora-B). A transactivator founder line that strongly expressed PF4-driven tTA-viral protein 16 (VP16) was crossbred to a responder line. The homozygous double-transgenic mouse line exhibited doxycycline-dependent transgene overexpression in MKs and platelets. Using this line, platelets were conveniently indicated at sites of induced stress by β-galactosidase staining. In addition, we confirmed our earlier report on effects of constitutive expression of Aurora-B, indicating a tight regulation at protein level and a modest effect on MK ploidy. Hence, we generated a new line, PF4-tTA-VP16, that is available for conditionally overexpressing genes of interest in the MK/platelet lineage in vivo.
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| 27. |
- Nguyen, Hao G., et al.
(författare)
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Deregulated Aurora-B induced tetraploidy promotes tumorigenesis
- 2009
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Ingår i: The FASEB Journal. - : Wiley. - 0892-6638 .- 1530-6860. ; 23:8, s. 2741-2748
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Tidskriftsartikel (refereegranskat)abstract
- High expression of Aurora-B has been observed in various cancers, and inhibition of this kinase has been shown to halt cellular proliferation. However, the mechanism of effect of Aurora-B on cellular transformation has not been fully explored. Here, we show that overexpression of Aurora-B in murine epithelial cells promotes generation of tetraploids. In search of a related mechanism, spectral karyotyping was carried out, showing premature chromatid separation (PCS). Of interest, PCS is a hallmark of Robert's syndrome, which also involves cellular polyploidy and aneuploidy. Sorted tetraploid Aurora-B-overexpressing cells promoted significant mammary epithelial cancers when injected into nude mice, as compared to injection of nonfractionated cells, suggesting that tetraploidy is an important mediator of Aurora-B-induced tumorigenesis. Comparative chromosome hybridization performed on DNA derived from tetraploid cell-induced tumors indicates amplifications and deletions of regions throughout the genome, which include tumor-promoting or tumor-suppressing genes, respectively. Thus, sustained expression of Aurora-B induces tetraploidy, which, in turn, facilitates genomic instability and tumor development in a xenograft model
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| 28. |
- Papadantonakis, Nicholas, et al.
(författare)
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Direct visualization of the endomitotic cell cycle in living megakaryocytes : differential patterns in low and high ploidy cells
- 2008
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Ingår i: Cell Cycle. - : Informa UK Limited. - 1538-4101 .- 1551-4005. ; 7:15, s. 2352-2356
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Tidskriftsartikel (refereegranskat)abstract
- Endomitosis in megakaryocytes (MKs) involves repeated DNA replication in the absence of cytokinesis and is a crucial part of MK development. However, chromosomal dynamics have never been observed in living MKs. We developed a new transgenic mouse model in which the expression of human histone H2B fused in-frame to green fluorescent protein is targeted to MKs. Ex vivo time-lapse microscopy analysis indicated that chromosomal condensation occurs at early mitosis in all MKs. In high ploidy MKs (≥ 8N), late anaphase was marked by a ring-type alignment of chromosomes with multiple territories formed between them. By contrast, in low ploidy MKs mitotic chromosomes segregated to form two groups separated by a clear space before re-joining to one cluster. This is the first study to document chromosomal segregation patterns during endomitosis ex vivo and to indicate their potential differential regulation in low and high ploidy cells.
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| 29. |
- Young, D., et al.
(författare)
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The A2b adenosine receptor protects against inflammation and excessive vascular adhesion
- 2006
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Ingår i: Journal of Clinical Investigation. - 0021-9738 .- 1558-8238. ; 116:7, s. 1913-1923
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Tidskriftsartikel (refereegranskat)abstract
- Adenosine has been described as playing a role in the control of inflammation, but it has not been certain which of its receptors mediate this effect. Here, we generated an A2B adenosine receptor-knockout/reporter gene-knock-in (A2BAR-knockout/reporter gene-knock-in) mouse model and showed receptor gene expression in the vasculature and macrophages, the ablation of which causes low-grade inflammation compared with age-, sex-, and strain-matched control mice. Augmentation of proinflammatory cytokines, such as TNF-alpha, and a consequent downregulation of IkappaB-alpha are the underlying mechanisms for an observed upregulation of adhesion molecules in the vasculature of these A2BAR-null mice. Intriguingly, leukocyte adhesion to the vasculature is significantly increased in the A2BAR-knockout mice. Exposure to an endotoxin results in augmented proinflammatory cytokine levels in A2BAR-null mice compared with control mice. Bone marrow transplantations indicated that bone marrow (and to a lesser extent vascular) A2BARs regulate these processes. Hence, we identify the A2BAR as a new critical regulator of inflammation and vascular adhesion primarily via signals from hematopoietic cells to the vasculature, focusing attention on the receptor as a therapeutic target
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| 30. |
- Özkaya Sahin, Gülsen, et al.
(författare)
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Generation of neutralizing antibodies and divergence of SIVmac239 in cynomolgus macaques following short-term early antiretroviral therapy.
- 2010
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Ingår i: PLoS Pathogens. - : Public Library of Science (PLoS). - 1553-7366 .- 1553-7374. ; 6:9
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Tidskriftsartikel (refereegranskat)abstract
- Neutralizing antibodies (NAb) able to react to heterologous viruses are generated during natural HIV-1 infection in some individuals. Further knowledge is required in order to understand the factors contributing to induction of cross-reactive NAb responses. Here a well-established model of experimental pathogenic infection in cynomolgus macaques, which reproduces long-lasting HIV-1 infection, was used to study the NAb response as well as the viral evolution of the highly neutralization-resistant SIVmac239. Twelve animals were infected intravenously with SIVmac239. Antiretroviral therapy (ART) was initiated ten days post-inoculation and administered daily for four months. Viral load, CD4(+) T-cell counts, total IgG levels, and breadth as well as strength of NAb in plasma were compared simultaneously over 14 months. In addition, envs from plasma samples were sequenced at three time points in all animals in order to assess viral evolution. We report here that seven of the 12 animals controlled viremia to below 10(4) copies/ml of plasma after discontinuation of ART and that this control was associated with a low level of evolutionary divergence. Macaques that controlled viral load developed broader NAb responses early on. Furthermore, escape mutations, such as V67M and R751G, were identified in virus sequenced from all animals with uncontrolled viremia. Bayesian estimation of ancestral population genetic diversity (PGD) showed an increase in this value in non-controlling or transient-controlling animals during the first 5.5 months of infection, in contrast to virus-controlling animals. Similarly, non- or transient controllers displayed more positively-selected amino-acid substitutions. An early increase in PGD, resulting in the generation of positively-selected amino-acid substitutions, greater divergence and relative high viral load after ART withdrawal, may have contributed to the generation of potent NAb in several animals after SIVmac239 infection. However, early broad NAb responses correlated with relatively preserved CD4(+) T-cell numbers, low viral load and limited viral divergence.
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