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- Arnberg, Lars, et al.
(författare)
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Solvent refining of silicon for solar cells –some practical aspects
- 2020
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Ingår i: Journal of Crystal Growth. - : Elsevier B.V.. - 0022-0248 .- 1873-5002. ; 531
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Tidskriftsartikel (refereegranskat)abstract
- Solvent refinement has been suggested as an energy- and cost-efficient process to produce high purity silicon for photovoltaic solar cells. In this process, metallurgical grade silicon is dissolved in a liquid metal e.g. Al at high temperature. High purity silicon crystals can then be precipitated by decreasing the temperature and extracted from the melt. Residual aluminium is then removed by leaching, and after remelting and directional solidification, the purified silicon can be used as silicon for solar cells. Metallurgical grade silicon (99 wt%Si) with iron as the main impurity has been dissolved to 40 wt% in liquid aluminium at 1000 °C. Silicon crystals have been extracted slightly above the eutectic temperature. The crystals have then been leached in 10% hydrochloric acid at room temperature. Silicon crystal have been sorted into three size fraction which have been melted separately and thereafter analyzed by light optical- and electron microscopy with EDS analysis. After leaching, extracted material has been remelted together with silicon oxide in order to oxidize residual aluminium. The extracted material contains significant amounts of residual Al-Si eutectic. The aluminium has not been removed completely by the leaching and insoluble metal rich intermetallic compounds have been found in the smallest size fraction. The residual aluminium can be further reduced by oxidation by silicon oxide and sedimentation of the aluminium oxide.
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- Arnberg, Niklas, et al.
(författare)
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Adenovirus type 37 binds to cell surface sialic acid through a charge-dependent interaction
- 2002
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Ingår i: Virology. - : Elsevier. - 0042-6822 .- 1096-0341. ; 302:1, s. 33-43
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Tidskriftsartikel (refereegranskat)abstract
- Most adenoviruses use the coxsackie-adenovirus receptor (CAR) as a major cellular receptor. We have shown recently that adenovirus types 8, 19a, and 37, which are the major causes of epidemic keratoconjunctivitis, use sialic acid rather than CAR as a major cellular receptor. The predicted isoelectric point of the receptor-interacting knob domain in the adenovirus fiber protein is unusually high (9.0-9.1) in type 8, 19a, and 37. The pKa of sialic acid is low, 2.6, implying a possible involvement of charge in fiber knob-sialic acid interactions. Here we show that (i) positively charged adenovirus knobs require sialic acid for efficient cell membrane interactions; (ii) viral and knob interactions with immobilized sialic acid or cell-surface sialic acid are sensitive to increased ionic strength; (iii) negatively charged molecules such as sulfated glycosaminoglycans inhibit the binding of virions to target cells in a nonspecific, charge-dependent manner; and that (iv) the ability of adenovirus knobs to interact with sialic acid correlates with the overall charge on the top surface of the respective knobs as predicted by homology modeling. Taken together, the results presented provide strong evidence for a charge mechanism during the interaction between the Ad37 fiber knob and sialic acid.
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- Arnberg, Niklas, et al.
(författare)
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Adenovirus type 37 uses sialic acid as a cellular receptor
- 2000
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Ingår i: Journal of Virology. - 0022-538X .- 1098-5514. ; 74:1, s. 42-48
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Tidskriftsartikel (refereegranskat)abstract
- Two cellular receptors for adenovirus, coxsackievirus-adenovirus receptor (CAR) and major histocompatibility complex class I (MHC-I) alpha2, have recently been identified. In the absence of CAR, MHC-I alpha2 has been suggested to serve as a cellular attachment protein for subgenus C adenoviruses, while members from all subgenera except subgenus B have been shown to interact with CAR. We have found that adenovirus type 37 (Ad37) attachment to CAR-expressing CHO cells was no better than that to CHO cells lacking CAR expression, suggesting that CAR is not used by Ad37 during attachment. Instead, we have identified sialic acid as a third adenovirus receptor moiety. First, Ad37 attachment to both CAR-expressing CHO cells and MHC-I alpha2-expressing Daudi cells was sensitive to neuraminidase treatment, which eliminates sialic acid on the cell surface. Second, Ad37 attachment to sialic acid-expressing Pro-5 cells was more than 10-fold stronger than that to the Pro-5 subline Lec2, which is deficient in sialic acid expression. Third, neuraminidase treatment of A549 cells caused a 60% decrease in Ad37 replication in a fluorescent-focus assay. Moreover, the receptor sialoconjugate is most probably a glycoprotein rather than a ganglioside, since Ad37 attachment to sialic acid-expressing Pro-5 cells was sensitive to protease treatment. Ad37 attachment to Pro-5 cells occurs via alpha(2-->3)-linked sialic acid saccharides rather than alpha(2-->6)-linked ones, since (i) alpha(2-->3)-specific but not alpha(2-->6)-specific lectins blocked Ad37 attachment to Pro-5 cells and (ii) pretreatment of Pro-5 cells with alpha(2-->3)-specific neuraminidase resulted in decreased Ad37 binding. Taken together, these results suggest that, unlike Ad5, Ad37 makes use of alpha(2-->3)-linked sialic acid saccharides on glycoproteins for entry instead of using CAR or MHC-I alpha2.
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- Arnberg, Niklas, et al.
(författare)
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Initial interactions of subgenus D adenoviruses with A549 cellular receptors : sialic acid versus alpha(v) integrins
- 2000
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Ingår i: Journal of Virology. - 0022-538X .- 1098-5514. ; 74:16, s. 7691-3
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Tidskriftsartikel (refereegranskat)abstract
- Selected members of the adenovirus family have been shown to interact with the coxsackie adenovirus receptor, alpha(v) integrins, and sialic acid on target cells. Initial interactions of subgenus D adenoviruses with target cells have until now been poorly characterized. Here, we demonstrate that adenovirus type 8 (Ad8), Ad19a, and Ad37 use sialic acid as a functional cellular receptor, whereas the Ad9 and Ad19 prototypes do not.
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