| 1. |
- Allgurén, Thomas, 1986, et al.
(författare)
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Investigation of the Behavior of Alkali Chlorides during Sulfur Recirculation in a Waste-to-Energy Facility
- 2018
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- High temperature corrosion related issues are known problems for Waste-to-Energy facilities where the formation of alkali chlorides is among the most problematic species formed during the combustion. Sulfur Recirculation is a novel technology developed to reduce the chlorine content in the ash and in that way also the corrosivity of the ash. This concept has been installed at the Maabjerg Energy Center (MEC) in Denmark. This work aims to take a first step towards a reaction kinetics based model that can describe systems like the MEC boiler and to evaluate the impact of Sulfur Recirculation. This is done by implementing a plug flow reactor model in the software Chemkin. Previously obtained data from on-site experiments and CFD simulations is used as input to the model. The model is focused on describing the sulfation of alkali chlorides and the result from the model is compared to experiments. The model is able to predict the degree of sulfation with less than 10% deviation from the experimental results. Both the experiment and the model show a clear benefit from implementing sulfur recirculation which lowers the chlorine content in the up to as much as 70%. It is, however, also shown that the results are sensitive towards several of the assumptions made. Even though there is a relatively good agreement in final sulfation between model and experiments the model is not able to represent the detailed chemistry in a realistic way in its current state; further development is required.
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| 2. |
- Li, Lu, 1964, et al.
(författare)
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Epigallocatechin gallate increases the formation of cytosolic lipid droplets and decreases the secretion of apoB-100 VLDL
- 2006
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Ingår i: J Lipid Res. - 0022-2275. ; 47:1, s. 67-77
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Tidskriftsartikel (refereegranskat)abstract
- Epigallocatechin gallate (EGCG) increases the formation of cytosolic lipid droplets by a mechanism that is independent of the rate of triglyceride biosynthesis and involves an enhanced fusion between lipid droplets, a process that is crucial for their growth in size. EGCG treatment reduced the secretion of both triglycerides and apolipoprotein B-100 (apoB-100) VLDLs but not of transferrin, albumin, or total proteins, indicating that EGCG diverts triglycerides from VLDL assembly to storage in the cytosol. This is further supported by the observed increase in both intracellular degradation of apoB-100 and ubiquitination of the protein (indicative of increased proteasomal degradation) in EGCG-treated cells. EGCG did not interfere with the microsomal triglyceride transfer protein, and the effect of EGCG on the secretion of VLDLs was found to be independent of the LDL receptor. Thus, our results indicate that EGCG promotes the accumulation of triglycerides in cytosolic lipid droplets, thereby diverting lipids from the assembly of VLDL to storage in the cytosol. Our results also indicate that the accumulation of lipids in the cytosol is not always associated with increased secretion of VLDL.
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| 3. |
- Mukama, Evode, 1968-
(författare)
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Information and Communication Technology in Teacher Education : Thinking and learning in computer‐supported social practice
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this thesis is to investigate how new knowledge can be developed in computer-supported social practice. Participants were selected from newly qualified secondary school teachers and student teachers at a higher education institution in Rwanda. The thesis consists of four empirical case studies, the findings of which were analysed from a sociocultural perspective. In the first study, it has been shown that novice teachers are motivated to acquire information and communication technology (ICT) and to use it in their teaching and learning. The study also reveals that they succeed in situations where school administrators grant them easy access to computers. This implies a need to develop school-based curricula and appropriate pedagogy in the area of ICT literacy, which can allow teachers to develop critical reflection vis-à-vis the new technology and enable them to cope with change in social practice. In the second study, it has been shown that, while acquiring hands-on computer skills in small task-based groups, student teachers can adopt one of the three major learning patterns: individual-led, group-led, or individual-group hybrid-led. Moreover, the study shows that the group-led framework seems to create a supportive environment for knowledge building. This may require that students receive the right kind of teacher assistance and focus on criterion-referenced reflection to regulate their learning. The findings of the third article reveal that students coping with web-based literature face a twofold reality of learning discourse rooted in their sociocultural and educational contexts: the one conveyed through the foreign languages in which they are instructed, the other whose vehicle is their native language. The study suggests an alternative way of constructing a substantial learning discourse based on dissolution of language boundaries. The fourth article shows that appropriation of ICT use can stem from learning conditions including users’ motivation and their participation in social practice. Additionally, it can stem from collaboration between active users and other students. Given this, the study suggests that active ICT users can play a role as agents of change in the implementation of the new technology. Together, the four studies show that thinking and learning with ICT can develop through the interplay of mediation, learning conditions, collaboration and critical reflection.
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| 4. |
- Alfonsson, Sven, et al.
(författare)
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The effects of clinical supervision on supervisees and patients in cognitive-behavioral therapy : a study protocol for a systematic review
- 2017
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Ingår i: Systematic Reviews. - : Springer Science and Business Media LLC. - 2046-4053. ; 6:94, s. 1-6
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Forskningsöversikt (refereegranskat)abstract
- Background: Clinical supervision by a senior therapist is a very common practice in psychotherapist training and psychiatric care settings. Though clinical supervision is advocated by most educational and governing institutions, the effects of clinical supervision on the supervisees ’ competence, e.g., attitudes, behaviors, and skills, as well as on treatment outcomes and other patient variables are debated and largely unknown. Evidence-based practice is advocated in clinical settings but has not yet been fully implemented in educational or clinical training settings. The aim of this systematic review is to synthesize and present the empirical literature regarding effects of clinical supervision in cognitive-behavioral therapy. Methods: This study will include a systematic review of the literature to identify studies that have empirically investigated the effects of supervision on supervised psychotherapists and/or the supervisees ’ patients. A comprehensive search strategy will be conducted to identify published controlled studies indexed in the MEDLINE, EMBASE, PsycINFO, and Cochrane Library databases. Data on supervision outcomes in both psychotherapists and their patients will be extracted, synthesized, and reported. Risk of bias and quality of the included studies will be assessed systematically. Discussion: This systematic review will rigorously follow established guidelines for systematic reviews in order to summarize and present the evidence base for clinical supervision in cognitive-behavioral therapy and may aid further research and discussion in this area.
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| 5. |
- Andersson, Linda, 1973, et al.
(författare)
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PLD1 and ERK2 regulate cytosolic lipid droplet formation
- 2006
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Ingår i: J Cell Sci. ; 119:Pt 11, s. 2246-57
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Tidskriftsartikel (refereegranskat)abstract
- We have previously uncovered roles for phospholipase D (PLD) and an unknown cytosolic protein in the formation of cytosolic lipid droplets using a cell-free system. In this report, PLD1 has been identified as the relevant isoform, and extracellular signal-regulated kinase 2 (ERK2) as the cytosolic protein. Increased expression of PLD1 increased lipid droplet formation whereas knockdown of PLD1 using siRNA was inhibitory. A role for ERK2 in basal lipid droplet formation was revealed by overexpression or microinjection, and ablation by siRNA knockdown or pharmacological inhibition. Similar manipulations of other Map kinases such as ERK1, JNK1 or JNK2 and p38alpha or p38beta were without effect. Insulin stimulated the formation of lipid droplets and this stimulation was inhibited by knockdown of PLD1 (by siRNA) and by inhibition or knockdown (by siRNA) of ERK2. Inhibition of ERK2 eliminated the effect of PLD1 on lipid droplet formation without affecting PLD1 activity, suggesting that PLD1 functions upstream of ERK2. ERK2 increased the phosphorylation of dynein which increased the amount of the protein on ADRP-containing lipid droplets. Microinjection of antibodies to dynein strongly inhibited the formation of lipid droplets, demonstrating that dynein has a central role in this formation. Thus dynein is a possible target for ERK2.
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| 6. |
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| 7. |
- Andersson, Sven, 1968, et al.
(författare)
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High Temperature Corrosion and Dioxin Abatement Using Sulfur Recirculation in a Waste-to-Energy Plant
- 2019
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Ingår i: Detritus. - : Eurowaste SRL. - 2611-4127 .- 2611-4135. ; 5:Mars, s. 92-98
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Tidskriftsartikel (refereegranskat)abstract
- Sulfur Recirculation is a novel technique for reducing the high temperature corrosion and dioxin formation in Waste-to-Energy plants by recirculating sulfur from the wet flue gas cleaning back to the boiler. This is achieved by separating SO2 from the flue gas in a wet scrubber downstream of a HCl scrubber. H2O2 dosed into the scrubber reacts with SO, in the gas and produces a 15-25 wt% H2SO4 solution, which is injected into the boiler producing SO2, thus creating a sulfur loop. The first permanent full-scale installation has been in operation in one of the two commercial full-scale Waste-to Energy boilers at Maabjerg Energy Center (MEC) in Denmark since October 2016. The recirculated sulfur increased the gas concentration of SO2 by a factor of 2-3 in the boiler, thereby enhancing the sulfation of corrosive alkali chlorides to non-corrosive alkali sulfates. The chlorine content of the superheater deposits decreased by 85%, and the superheater corrosion rate decreased by 40-90% during the first year of operation. The dioxin concentrations upstream of the dioxin removal system decreased by 75% and the dioxin emissions decreased by 72% with Sulfur Recirculation in operation. Furthermore, the sulfate containing effluent water was almost eliminated due to the increased sulfation of the ashes and deposits.
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| 8. |
- Andersson, Sven, 1968
(författare)
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Network Disruption and Turbulence in Fibre Suspensions
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The production of paper pulp involves the handling of large quantities of fibre suspensions. Today's call for energy efficiency and environmentally sound processes has led to the development of MC (Medium Consistency) technology. Most unit operations in the pulp industry are now routinely performed at concentrations higher than 10 %, at which fibre suspensions behave as solids at low shear rates. If the shear rate is sufficiently high, however, the behaviour of MC suspensions resembles that of pure water. This thesis deals with the network strength (or yield stress) of fibre suspensions, which is a suspension property that may be related to the flow transitions of fibre suspensions. The main cause of network strength is the frictional force in the contact points between single fibres. A novel measurement method was developed to measure the inter-fibre friction of single pulp fibres. The coefficient of friction was found to be around 0.6 for dry kraft fibres and range between 0.6-0.8 for wet kraft fibres. A mechanistic model has been developed for predicting the network strength of homogeneous suspensions. It gives fair agreement with experimental yield stress data for homogeneous suspensions; the experimental values for flocculated suspensions were lower. The turbulent flow of pulp fibre suspensions at Medium Consistency has been subject to much speculation due to the absence of direct measurements. A rotary shear-tester, resembling an industrial mixer, was designed and constructed to permit direct velocity measurements using Laser Doppler Anemometry (LDA). The fibre concentrations were up to 20 wt % using a refractive index matched glass fibre suspension. Both mean and fluctuating velocities were found to be close to those of single-phase flow at flows above a critical rotational speed. At lower rotational speeds, the turbulence was strongly suppressed, whereas the mean velocities were close to those of fully developed turbulent flow. The single-phase flow was compared to single-phase CFD (Computational Fluid Dynamics) calculations using the sliding-grid technique. The flow field was predicted well by using the standard k-epsilon turbulence model, but the absolute values were 25 % too low. Boundary-layer measurements, including the viscous sub-layer, were performed as well. Linear velocity profiles were obtained close to the wall for both the single-phase and the tested suspensions. Further from the wall, flatter velocity profiles were obtained in the fibre suspensions than for single-phase flow.
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| 9. |
- Andersson, Sven, 1968, et al.
(författare)
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Sulphur recirculation for high temperature corrosion and dioxin abatement in Waste-to-Energy boilers
- 2018
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Ingår i: Sulphur 2018 + Sulphuric Acid. ; , s. 315-320
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Konferensbidrag (refereegranskat)abstract
- Sulphur Recirculation is a new patented technology for reducing high temperature boiler corrosion and dioxin formation in Waste-to-Energy plants. SO2 is separated from a tail end wet scrubber using H2O2, producing a 15-25wt% H2SO4 solution, which is injected into the boiler producing SO2, thus creating a sulphur loop. The recirculated sulphur will increase the gas concentration of SO2 in the boiler and decrease the Cl/S ratio of the deposits and ashes, thus producing a less corrosive environment for the superheaters. Furthermore, the lower chlorine content of the boiler deposits also significantly decreased the dioxin formation rates as well as dioxin emissions. Sulphur Recirculation was initially demonstrated in pilot plant tests as well as full-scale tests at a Waste to Energy plant in Göteborg (Sweden) during nearly two months of operation. Babcock & Wilcox Vølund AB in Sweden has installed their Sulphur Recirculation technology in one of the two Waste-to Energy lines at Maabjerg Energy Center (MEC) in Denmark in order to combat high temperature corrosion and dioxin formation. This is the first commercial installation and it has been operating since mid-October 2016. Sulphur Recirculation decreased the high temperature corrosion rates of the superheaters in this full-scale installation by approximately 50%, which may increase green electricity production from combustion of biomass and waste in the future. Furthermore, the dioxin gas concentrations decreased by 72%. Sulphur Recirculation almost entirely decreased the need for costly road transports of effluent sulphate water for the Sulphur Recirculation line, since most sulphur from the waste now ends up in the ashes instead of creating a surplus dilute Na2SO4 solution. The sulphur content of the waste varies with time, which may create periods of sulphur surplus and deficit respectively. Most of these variations are being evened out by a storage vessel for H2SO4. These variations may facilitate a small market of waste sulphuric acid between plants in the future.
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| 10. |
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