| 1. |
- Andersson, Johan, et al.
(författare)
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Biologisk metanisering av syngas från förgasning och pyrolys - lovande koncept mot implementering
- 2024
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Biological methanation of syngas from pyrolysis and gasification – promising concepts for implementation The need for increased biogas production is significant, and in the EU, there are plans for a substantial expansion in the coming years through the RePowerEU initiative. Part of the increase will come from the expansion of conventional digestion technology, where organic materials such as food waste, manure, and crop residues are used for biogas production. However, to meet the future increased demand, it is also necessary to utilize more difficult-to-digest substrates, such as biomass rich in lignocellulose, for biogas production. This could be forest residues such as branches and tops, sawdust, or bark. This type of substrates cannot be used in a conventional digestion process, and other technology chains are therefore required to convert such biomass into biomethane. This can be done by first converting the biomass into syngas through a thermochemical process such as gasification or pyrolysis. This is followed by a methanation process where the syngas is converted into biogas, and finally, the gas is upgraded to reach biomethane quality. These types of technology chains are not currently available on a commercial scale, but they have been demonstrated, for example, through the Gobigas project, where gasification was followed by catalytic methanation for biomethane production. As full-scale implementation of catalytic methanation of bio-syngas has not yet been achieved, thereis a need to develop alternative conversion technologies that can more cost-effectively achieve the methanation of woody biomass. One possible opportunity for to this is to apply biological methanation instead of a catalytic process. A biological process comes with several advantages, including a greater ability to handle contaminants, higher selectivity in the conversion of syngas, and operation at relatively low temperature and pressure, which simplifies material selection and reactor design. RISE, together with its partners, are developing a concept based on biological methanation of syngas. This project has examined the biological process's ability to handle contaminants in syngas through continuous experiments in carrier-filled trickle bed reactors with an active volume of 5 liters. The process's ability to handle and break down contaminants is an important parameter that can affect and simplify the design of the gas cleaning that occurs after gasification or pyrolysis. Another aspect of the project has been to put the experimental results into context at the concept and system level. Different production techniques for syngas have been mapped out, which could be combined with biological methanation. Based on the mapping, three types of plants have been selected for more detailed analyses of techno-economics, carbon footprint, and opportunities for increased carbon efficiency. The methanation experiments lasted for 552 days, and overall, it was a stable process with high turnover of syngas and high methane production over a long time. There have been some operational disturbances, mainly related to the supply of gas to the process (i.e. delivery of gas cylinders). However, biochemical inhibition or disturbances have been rare, demonstrating a high robustness for biological methanation of syngas. The breakdown of contaminants has been excellent in the process, with levels decreasing below the detection limit. At the same time, as contaminants have been continuously added to the process, microbiology has been able to maintain high turnover of hydrogen and carbon monoxide to methane. The specific methane production was high both during the reference period without contaminants and during the experimental periods with added contaminants. During long periods, the specific methane production has been around 4 L CH4/Lbed volume /day, which is about 4 times higher than our previously achieved results. The transition to thermophilic temperature and using carriers with higher effective surface area has contributed to this increase. During the project, three types of plants have been selected for more detailed analysis: 1) Gasification with Cortus process, which generates a relatively clean syngas with minimal purification needs before biological methanation. There is no need for co-location with a heating plant, but it is an advantage if there is access to the district heating network to sell waste heat. 2) Gasification with Bioshares' concept, where the gasifier is integrated into a larger cogeneration plant and where the produced syngas is purified with an RME-scrubber before biological methanation. Co-location with a larger cogeneration plant provides interesting synergies and integration opportunities, but also sets the boundaries for where the plants can be located. 3) Slow pyrolysis according to Envigas' concept, where the primary product is biochar and where the produced syngas is seen as a by-product. The syngas contains some impurities but generally requires no other purification than cooling to the right temperature (condensing out tars) before being added to biological methanation. This type of plant differs from plant types 1-2 in that the syngas formed is not the primary product, and the syngas has a relatively low energy value compared to the others. Syngas from plant types 2 and 3 contains some hydrocarbons (C1-C3) that are considered inert over the methanation step and therefore do not negatively affect the process. This means that heavier hydrocarbons do not need to be removed upstream, which would likely have been required with catalytic methanation. This leads to a higher system efficiency, and the need for reactor capacity for biological methanation decreases since there is less gas to be processed (more of the end-product consists of hydrocarbons already formed during the thermochemical conversion upstream). For all plant types, downstream of the methanation step, there is a need for further gas purification and upgrading. During the upgrading step carbon dioxide is separated to reach the product specification required by the end user. If long distance distribution is required a final process step consisting of a liquefaction plant for the production of liquid biogas (LBG) can be added to the concept. As another option, the systems can be supplemented with treatment of the carbon dioxide flow out of the upgrading plant, where the flow is processed by drying, compression, and cooling to produce liquid carbon dioxide. For plant type 2, where benzene is present in the syngas, this gas is expected to be separated with relatively high precision in the system and thereby generate a small flow of liquid benzene as a side product. The carbon dioxide emissions for the final product LBG are in the range of 1.6 to 2.6 gCO2-eq/MJLBG, which compares favorably to other types of second-generation biofuels. Compared to fossil gas, the reduction in greenhouse gas emissions is 96-97%. The carbon efficiency of the systems can be significantly increased if excess carbon dioxide is utilized either through BECCS or BECCU. If the carbon dioxide stream from the upgrading plant is processed into liquid carbon dioxide, the production cost is estimated to be 187-204 SEK/ton. If the product is to be sent to permanent storage the cost for transportation and storage would need to be added to estimate total cost of BECCS, but this is out of scope for the current project.. Assuming that BECCS is applied and that the entire carbon sink is allocated to the final product LBG, this will result in negative emissions in the range of -35 to -104 gCO2-eq/MJLBG. An alternative is to utilize excess carbon dioxide directly in the methanation process by boosting incoming gas with extra hydrogen. Hydrogen and carbon dioxide are then converted by methanogens, which generates extra methane. Since the addition of extra hydrogen is assumed to come from electrolysis, the additional methane production can likely be classified as electrofuel, so-called e-methane. The techno-economic evaluation results in a production cost ranging from 740 to 1300 SEK/MWhLBG, including all sensitivity scenarios. The lower price scenarios include a lower investment cost, which can be assumed to represent cases with public investment support. Overall, a large part of the scenarios are considered to be within the range of what can be considered market relevant production costs. This leads to the conclusion that there is techno-economic potential at this stage to justify continued development of concepts based on biological methanation of syngas. With scaling up and continued development in the right direction, the concepts may eventually lead to cost-effective utilization of forest residues for the production of biomethane at a commercially relevant scale. The next step in the development is scaling up to pilot scale, which will take place during 2023-2025 through an EU-funded project and will be carried out by RISE, Wärtsilä, Cortus and Swedish Gas Association. A pilot plant for biological methanation will then be operated with syngas from Cortus' gasifier in Höganäs.
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| 2. |
- Bäck, Sophia, et al.
(författare)
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Comprehensive left atrial flow component analysis reveals abnormal flow patterns in paroxysmal atrial fibrillation
- 2024
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Ingår i: American Journal of Physiology. Heart and Circulatory Physiology. - : AMER PHYSIOLOGICAL SOC. - 0363-6135 .- 1522-1539. ; 326:3, s. H511-H521
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Tidskriftsartikel (refereegranskat)abstract
- Left atrial (LA) blood flow plays an important role in diseases such as atrial fibrillation (AF) and atrial cardiomyopathy since alterations in the blood flow might lead to thrombus formation and stroke. Using traditional techniques, such as echocardiography, atrial flow velocities can be measured at the pulmonary veins and the mitral valve, but a comprehensive understanding of the three-dimensional atrial flow field is missing. Previously, ventricular flow has been analyzed using flow component analysis, revealing new insights into ventricular flow and function. Thus, the aim of this project was to develop a comprehensive flow component analysis method for the LA and explore its utility in 21 patients with paroxysmal atrial fibrillation compared with a control group of 8 participants. The flow field was derived from time-resolved CT acquired during sinus rhythm using computational fluid dynamics. Flow components were computed from particle tracking. We identified six atrial flow components: conduit, reservoir, delayed ejection, retained inflow, residual volume, and pulmonary vein backflow. It was shown that conduit flow, defined as blood entering and leaving the LA within the same diastolic phase, exists in most subjects. Although the volume of conduit and reservoir is similar in patients with paroxysmal AF in sinus rhythm and controls, the volume of the other components is increased in paroxysmal AF. Comprehensive quantification of LA flow using flow component analysis makes atrial blood flow quantifiable, thus facilitating investigation of mechanisms underlying atrial dysfunction and can increase understanding of atrial blood flow in disease progression and stroke risk. NEW & NOTEWORTHY We developed a new comprehensive approach to atrial blood component analysis that includes both conduit flow and residual volume and compared the flow components of atrial fibrillation (AF) patients in sinus rhythm with controls. Conduit and reservoir flow were similar between the groups, whereas components with longer residence time in the left atrium were increased in the AF group. This could add to the pathophysiological understanding of atrial diseases and possibly clinical management.
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| 3. |
- Walser, Marion, 1961, et al.
(författare)
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Brain tissue haemoglobin expression in saline-perfused vs non-perfused rodents
- 2024
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Ingår i: Heliyon. - 2405-8440. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- Haemoglobin beta (Hbb) and delta-aminolevulinate synthase 2 (Alas2) messenger RNA (mRNA) is mainly found in immature red blood cells, reticulocytes, and not in mature erythrocytes. However, these are also expressed in other tissues such as brain cells, mostly neurons. Therefore, exact quantification of neural tissue homogenates may be confounded by remaining blood in the brain vasculature that may give falsely high values of Hbb/Alas2 expression. To investigate and compare the contribution of local Hbb/Alas2 expression, we investigated mRNA expression locally in the hippocampus and prefrontal cortex, in post-sacrifice saline-perfused and non-perfused mice and rats. Although there was a higher level of Hbb/Alas2 transcripts in the non-perfused animals, there was a significant mRNA expression in perfused brains that could at most partially be explained by remaining blood. Finally, we suggest that saline-perfusion should be recommended for quantification of brain Hbb/Alas2 transcripts in homogenates.
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| 4. |
- Almroth, Henrik, et al.
(författare)
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Haemodynamic changes after atrial fibrillation initiation in patients eligible for catheter ablation: a randomized controlled study
- 2023
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Ingår i: European Heart Journal Open. - : Oxford University Press. - 2752-4191. ; 3:6
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Tidskriftsartikel (refereegranskat)abstract
- AbstractAims: Atrial fibrillation (AF) haemodynamics is less well studied due to challenges explained by the nature of AF. Until now, no randomized data are available. This study evaluates haemodynamic variables after AF induction in a randomized setting.Methods and results: Forty-two patients with AF who had been referred for ablation to the University Hospital, Linköping, Sweden, and had no arrhythmias during the 4-day screening period were randomized to AF induction vs. control (2:1). Atrial fibrillation was induced by burst pacing after baseline intracardiac pressure measurements. Pressure changes in the right and left atrium (RA and LA), right ventricle (RV), and systolic and diastolic blood pressures (SBP and DBP) were evaluated 30 min after AF induction compared with the control group. A total of 11 women and 31 men (median age 60) with similar baseline characteristics were included (intervention n = 27, control group n = 15). After 30 min in AF, the RV end-diastolic pressure (RVEDP) and RV systolic pressure (RVSP) significantly reduced compared with baseline and between randomization groups (RVEDP: P = 0.016; RVSP: P = 0.001). Atrial fibrillation induction increased DBP in the intervention group compared with the control group (P = 0.02), unlike reactions in SBP (P = 0.178). Right atrium and LA mean pressure (RAm and LAm) responses did not differ significantly between the groups (RAm: P = 0.307; LAm: P = 0.784).Conclusion: Induced AF increased DBP and decreased RVEDP and RVSP. Our results allow us to understand some paroxysmal AF haemodynamics, which provides a haemodynamic rationale to support rhythm regulatory strategies to improve symptoms and outcomes.Trial registration number clinicaltrialsgov: No NCT01553045. https://clinicaltrials.gov/ct2/show/NCT01553045?term=NCT01553045&rank=1.
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| 5. |
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| 6. |
- Bäck, Sophia, et al.
(författare)
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Elevated atrial blood stasis in paroxysmal atrial fibrillation during sinus rhythm: a patient-specific computational fluid dynamics study
- 2023
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Ingår i: Frontiers in Cardiovascular Medicine. - : FRONTIERS MEDIA SA. - 2297-055X. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Atrial fibrillation (AF) is associated with an increased risk of stroke, often caused by thrombi that form in the left atrium (LA), and especially in the left atrial appendage (LAA). The underlying mechanism is not fully understood but is thought to be related to stagnant blood flow, which might be present despite sinus rhythm. However, measuring blood flow and stasis in the LAA is challenging due to its small size and low velocities. We aimed to compare the blood flow and stasis in the left atrium of paroxysmal AF patients with controls using computational fluid dynamics (CFD) simulations.Methods : The CFD simulations were based on time-resolved computed tomography including the patient-specific cardiac motion. The pipeline allowed for analysis of 21 patients with paroxysmal AF and 8 controls. Stasis was estimated by computing the blood residence time.Results and Discussion: Residence time was elevated in the AF group (p < 0.001). Linear regression analysis revealed that stasis was strongest associated with LA ejection ratio (p < 0.001, R-2 = 0.68) and the ratio of LA volume and left ventricular stroke volume (p < 0.001, R-2 = 0.81). Stroke risk due to LA thrombi could already be elevated in AF patients during sinus rhythm. In the future, patient specific CFD simulations may add to the assessment of this risk and support diagnosis and treatment.
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| 7. |
- Charitakis, Emmanouil, et al.
(författare)
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Predictors of recurrence after catheter ablation and electrical cardioversion of atrial fibrillation: an umbrella review of meta-analyses
- 2023
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Ingår i: Europace. - : OXFORD UNIV PRESS. - 1099-5129 .- 1532-2092. ; 25:1, s. 40-48
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Forskningsöversikt (refereegranskat)abstract
- Aims The recurrence rates after catheter ablation (CA) and direct current (DC) cardioversion remain high, although they have been established treatments of rhythm control of atrial fibrillation (AF). This umbrella review systematically appraises published meta-analyses of both observational and randomized controlled trials (RCTs) for the association of risk and protective factors for arrhythmia recurrence after CA and DC cardioversion of AF. Methods and results Three bibliographic databases were searched up to June 2021. Evidence of association was rated as convincing, highly suggestive, suggestive, weak, or not significant with respect to observational studies and as high, moderate, low, or very low with respect to RCTs, according to established criteria. Thirty-one meta-analyses were included. Of the 28 associations between CA and the risk of arrhythmia recurrence, none presented convincing evidence, and only the time from diagnosis to ablation over 1 year provided highly suggestive evidence. The association between hypertension and metabolic profile provided suggestive evidence. The associations of Class IC and III antiarrhythmic drugs use with the recurrence after DC cardioversion were supported by an intermediate level of evidence. Conclusion Although AF is a major health issue, few risk- and protective factors for AF recurrence have been identified. None of these factors examined were supported by convincing evidence, whereas established factors such as female gender and left atrial volume showed only weak association. An early CA strategy combined with treatment of metabolic syndrome and hypertension prior to CA may reduce the risk of arrhythmia recurrence. The use of antiarrhythmics can increase the success rate of DC cardioversion. Systematic review registration PROSPERO registry number: CRD42021270613.
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| 8. |
- Häggqvist, Henric, 1981-, et al.
(författare)
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240 years of Swedish terms of trade : structure, volatility, and connection to economic growth
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this paper we present new foreign trade- and price data to analyze Swedish terms of trade in the very long run, from 1780 to 2018. We examine what influenced the trend in the terms of trade in the long run, particularly in how it related to the general trade structure. We also analyze the volatility of the terms of trade, and discuss how it might have affected economic growth in Sweden. The index improved slowly but substantially over the century from 1850 to 1950, which was likely connected to another poignant trend, a steadily increasing share of manufactures and finished goods in the export basket. In comparative perspective, Sweden had more industrial exports and lower export concentration than most of the rest of the European periphery, as well as much lower terms of trade volatility. We find that the growth trend and low volatility of Swedish terms of trade was positively connected with economic growth, but only really so from about 1850 to 1913. During this period the development of the terms of trade was particularly connected to increasing investment in new industries. The years from 1914 to 1960 were on the other hand characterized by high volatility in the terms of trade, and was still connected to high growth rates, such as during the interwar period. Hence, we conclude that while low volatility was connected to the onset of Swedish industrialization, it was also possible to maintain high growth rates during periods of high terms of trade volatility.
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| 9. |
- Kondyli, Vasiliki, 1989-
(författare)
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Behavioural Principles for the Design of Human-Centred Cognitive Technologies : The Case of Visuo-Locomotive Experience
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The successful application, usability, and social emancipation of AI technologies necessitates that the design and implementation of technical systems be founded on human-centred principles, be it cognitive or behavioural, social, ethical etc. Towards this objective, this thesis develops an interdisciplinary methodology for embedding cognitive behavioural principles in the design and development of next-generation human-centred AI technologies that aim to assist and empower humans in everyday life.The interdisciplinary methodology developed in this research categorically focusses on two key aspects pertaining to human-centred technology design and engineering: (1) human behavioural precedents; and (2) cognitively founded representational and computational modalities:Human behavioural precedents are established by systematically analysing human visuo-locomotive experience during everyday activities involving (embodied) multimodal interactions. We conduct naturalistic behavioural experiments focusing on aspects of visual perception (e.g., inattention blindness) and spatial cognition (e.g., orientation, navigation) in diverse settings of everyday mobility. As specific -in-the-wild- experimental contexts, we focus on behavioural aspects involved in everyday (human) navigation and driving.Representational and computational modalities are developed based on cognitively-driven articulation of behavioural precedents. Particularly, a cognitive model of visuospatial complexity for grounding embodied multimodal interactions is developed by incorporating behavioural precedents pertaining to representations of space, motion, and interaction. Furthermore, precedents concerning human preferences are used as a basis for semantically-driven computational synthesis (e.g. in the generation and manipulation of spatial morphologies), and in the articulation of human-centred evaluation and standardisation of AI systems.As case studies we demonstrate the developed methodology in the backdrop of two application domains: (a) design assistance technologies, and (b) autonomous driving. More broadly, this thesis emphasises the need for embedding ecologically valid behavioural knowledge within the development of "human-centred" technologies. Furthermore, this research paves the way for the development of systems that understand, interpret and anticipate human behaviour under ecologically valid naturalistic circumstances.
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| 10. |
- Skibniewski, Mikolaj, et al.
(författare)
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Long-term antithrombotic therapy after coronary artery bypass grafting in patients with preoperative atrial fibrillation. A nationwide observational study from the SWEDEHEART registry
- 2023
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Ingår i: American Heart Journal. - : Elsevier BV. - 0002-8703 .- 1097-6744. ; 257, s. 69-77
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Tidskriftsartikel (refereegranskat)abstract
- Aims To provide data guiding long-term antithrombotic therapy after coronar y arter y by-pass grafting (CABG) in patients with preoperative atrial fibrillation (AF). Methods and results From the SWEDEHEART registry, we included all patients, between January 2006 and September 2016, with preoperative AF and CHA2DS2-VASC score >2, undergoing CABG. Based on dispensed prescriptions 12 to 18 months after CABG, patients were divided in 3 groups: use of platelet inhibitors (PI) only, oral anticoagulant (OAC) only or a combination of OAC + PI. Outcomes were: Major adverse cardiac and cerebrovascular events (MACCE, [all-cause death, myocardial infarction, or stroke]), net adverse clinical events (NACE, [MACCE or bleeding]) and the individual components of NACE. Inverse probability of treatment weighting was used to adjust for the non-randomized study design. Among 2,564 patients, 1,040 (41%) were treated with PI alone, 1,064 (41%) with OAC alone, and 460 (18%) with PI + OAC. Treatment with PI alone was associated with higher risk for MACCE (adjusted HR 1.43, 95% CI 1.09-1.88), driven by higher risk for stroke and MI, compared with OAC alone. Treatment with PI + OAC, was associated with higher risk for NACE (adjusted HR 1.40, 95% CI 1.06-1.85), driven by higher risk for bleeds, compared with OAC alone. Conclusion In this real-world observational study, a high proportion of patients with AF, undergoing CABG, did not receive a long-term OAC therapy. Treatment with OAC alone was associated with a net clinical benefit, compared with PI alone or PI + OAC. (Am Heart J 2023;257:69-77.)
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