| 986051. |
- Maric, Jelena, 1983
(författare)
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Choice of bed material: a critical parameter in the optimization of dual fluidized bed systems
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Dual Fluidized Bed (DFB) gasification is a promising alternative method for the production of biofuels. In the DFB gasification process, the bed material, which is a crucial component of the process, has two possible roles: 1) to provide the heat needed for the gasification reaction; and 2) if it has catalytic properties, to improve the quality of the produced gas. Ash-forming elements that are introduced together with the biomass into the system can interact with the bed material, and therefore have catalytic potential. As they alternate between the different environments, and depending on the nature of the bonds formed between the bed material and ash elements, some of the inorganic compounds may be released in the gas phase, thereby influencing the final composition of the produced gas. The present work advances current understanding of how biomass ash-induced changes alter the impact of the bed material on the performance of a DFB gasifier. Thus, understanding the bed material-biomass ash interactions can be used to improve the performance of the system. By improving the gasification step, which is the main step in the biomass conversion, the costs associated with the downstream processes, and consequently, the overall cost of the biomass to biofuel pathway can be reduced. In addition, utilizing naturally occurring materials as catalytic bed materials is advantageous given their relatively low price and low environmental impact which in terms of disposal of the material post-process. The work for this thesis was conducted at the Chalmers facility. The possibilities for process improvement were investigated by the use of different bed materials in the gasifier, as well as in a secondary upgrading step. When applied to the gasification step, the interactions between inorganics and bed material alter the chemical properties of the bed, thereby influencing the gasification process. Within the investigations presented in this thesis, six naturally occurring materials were tested in the beds. Tests with silica sand, olivine sand, and bauxite were performed in the Chalmers 2–4-MWth gasifier. For each tested material, the process was evaluated with respect to: 1) the composition of the produced gas; 2) the tar content; and 3) the physicochemical properties of the bed material. The key finding is that the transport of alkalis from the boiler to the gasifier, where they are released, is the major factor influencing the gas composition. An improved understanding the importance of potassium transport was crucial in salvaging the commissioning and start-up of the GoBiGas gasification system, which had suffered from the problem of insufficient gas quality. Even though a positive effect of alkali on the gasification is known, high levels of alkali entail a risk for agglomeration. In this regard, a natural ore of iron, ilmenite, was used in the Chalmers 12–MWth boiler as a material for fluidized bed combustion. It was found that ilmenite has the capability to store potassium in a non-releasable form, thereby decreasing the risk of bed agglomeration in fluidized bed boilers. To enable further upgrading of the gas produced by biomass gasification, two naturally occurring materials were tested in a Chemical Looping Reforming system: a manganese ore; and feldspar. Both materials were able to reform tars and persisted throughout the process with negligible decrease in activity.
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| 986052. |
- Maric, Jovana, et al.
(författare)
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Cytokine-induced endogenous production of prostaglandin D-2 is essential for human group 2 innate lymphoid cell activation
- 2019
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Ingår i: Journal of Allergy and Clinical Immunology. - : MOSBY-ELSEVIER. - 0091-6749 .- 1097-6825. ; 143:6, s. 2202-2214.e5
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Tidskriftsartikel (refereegranskat)abstract
- Objective: We set out to examine PG production in human ILC2s and the implications of such endogenous production on ILC2 function. Methods: The effects of the COX-1/2 inhibitor flurbiprofen, the hematopoietic prostaglandin D2 synthase (HPGDS) inhibitor KMN698, and the CRTH2 antagonist CAY10471 on human ILC2s were determined by assessing receptor and transcription factor expression, cytokine production, and gene expression with flow cytometry, ELISA, and quantitative RT-PCR, respectively. Concentrations of lipid mediators were measured by using liquid chromatography-tandem mass spectrometry and ELISA. Results: We show that ILC2s constitutively express HPGDS and upregulate COX-2 upon IL-2, IL-25, and IL-33 plus thymic stromal lymphopoietin stimulation. Consequently, PGD2 and its metabolites can be detected in ILC2 supernatants. We reveal that endogenously produced PGD2 is essential in cytokine-induced ILC2 activation because blocking of the COX-1/2 or HPGDS enzymes or the CRTH2 receptor abolishes ILC2 responses. Conclusion: PGD2 produced by ILC2s is, in a paracrine/autocrine manner, essential in cytokine-induced ILC2 activation. Hence we provide the detailed mechanism behind how CRTH2 antagonists represent promising therapeutic tools for allergic diseases by controlling ILC2 function.
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| 986053. |
- Maric, Jelena, 1983, et al.
(författare)
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Emissions of dioxins and furans during steam gasification of Automotive Shredder residue; experiences from the Chalmers 2–4-MW indirect gasifier
- 2020
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Ingår i: Waste Management. - : Elsevier BV. - 0956-053X .- 1879-2456. ; 102, s. 114-121
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Tidskriftsartikel (refereegranskat)abstract
- © 2019 Emissions of dioxins and furans during the gasification of Automotive Shredder Residue (ASR) were investigated. The experimental work was carried out in a Dual Fluidized Bed (DFB) system, which consists of a 2–4-MWth gasifier that is fluidized with steam, and an interconnected fluidized bed combustor that is fluidized with air. Two different ASR fractions with higher and lower contents of plastic were tested. Measurements were carried out in the flue gas stream exiting the combustion side of the DFB, as well as in the raw gas stream exiting the gasifier side. A calcium (lime) coat was applied to the flue gas filter to ensure compliance with the emissions regulations regarding the retention of HCl and dioxins. The results showed lower emissions of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/PCDF) in the flue gas when the raw gas derived from the ASR gasification was combusted, as compared to the direct combustion of ASR. The level of polychlorinated compounds in the flue gas before the lime-coated filter was 0.11 ng/m3N dry gas (I-TEQ) when gasification was used as a pre-step, as compared to 0.27 ng/m3N dry gas (I-TEQ) when the ASR was directly combusted. The raw gas produced by gasification contained very low levels of PCDD/PCDF, whereby the toxicity per kg of ASR was 0.17 ng/kgASR, as compared to 3.44 ng/kgASR after passage through the combustion and cooling sections and 0.34 ng/kgASR at the outlet after the lime-coated filter. A higher content of plastic in the ASR led to an increase in the levels of dioxins and furans in the raw gas, with the highest yield seen for highly chlorinated compounds, while higher temperature in the gasifier is shown to be beneficial in reducing dioxin formation.
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| 986054. |
- Maric, Jelena, 1983, et al.
(författare)
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Impact of Biomass Ash-Bauxite Bed Interactions on an Indirect Biomass Gasifier
- 2016
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 30:5, s. 4044-4052
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Tidskriftsartikel (refereegranskat)abstract
- The influence of interactions between biomass ash and bauxite bed material on the performance of an indirect gasification system was investigated. With bauxite as the starting material, changes in gasification performance over time were assessed through measurements of gas composition, the amount of tar in the gas, cold gas efficiency, and carbon conversion. As the operation progressed and interactions with ash elements occurred, the bauxite showed increased activities for tar decomposition and carbon conversion. Additional experiments with solid samples that were extracted from the gasifier were performed in a laboratory-scale reactor and revealed the activity of the bauxite toward a water gas shift reaction as well as an increased ability to transport oxygen. Further analyses of the same solid samples showed that the bauxite had been enriched with ash elements; specifically, catalytically active alkali metals were detected in leachable form. In general, bauxite has been shown as an interesting material from a fuel conversion point of view. However, the effect on fuel conversion has been overshadowed by the high oxygen transport ability of bauxite.
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| 986055. |
- Maric, Jasmina
(författare)
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INTERACTIVE DESIGN OF COLLABORATIVE ART PROJECT FOR 21ST CENTURY LEARNING
- 2019
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Ingår i: IADIS International Journal on WWW/Internet. - 1645-7641. ; 7:2, s. 28-43
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Tidskriftsartikel (refereegranskat)abstract
- While many of us researchers dream about the opportunity to design a collaborative art project that would connect our youth with big, mainstream cultural and educational institutions, we seldom analyse the challenges of such collaborations. This paper presents the user-centered, interdisciplinary interaction design (ID) of the collaborative digital art project. The project design is made in collaboration with the young participants of the Meet the Ministry project run by the Dance Company of the Opera House (DCOH) in Gothenburg, and the members of The Swedish School of Library and Information Science Social Media Studies (TSLIS) research group. Using the research through design approach to augment the outreach of the collaborative digital art project, enhance youth engagement with the contemporary dance, and learn from the young participants, we analyze the implications introduced by inter-institutional and interdisciplinary collaboration. This paper proposes a view which suggests that learning can be effective and pure joy, while at the same time delivering 21st-century skills to those who learn, and new conditions for social inclusion and sustainable society. One argument is that we need new teaching approaches to successfully prepare our youngest for the 21st century. The other reason is that we would be better off if the investments in our public institutions could positively influence a larger society, which would result in a more sustainable society. Drawing from the different scientific research experiences this paper calls for interdisciplinary and interinstitutional collaborative art projects as learning tools, and tools to leverage social sustainability
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| 986056. |
- Maric, Jasmina
(författare)
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Learning from the youth. The challenges of interdisciplinary, inter-institutional collaboration.
- 2020
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Ingår i: Cultural Management: Science and Education (CMSE). - 2512-6962. ; 4:1
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Tidskriftsartikel (refereegranskat)abstract
- If our contemporary society needs innovative solutions we argue that we need to learn from our youth. This paper presents the most prevailing issues that arose during the collaborative digital art project designed to connect our youth with big, mainstream cultural institution, and to augment the outreach of the project. By using the research through design approach and surveys with participants, we analyse the implications introduced by inter-institutional and interdisciplinary collaboration. We claim that such collaborations are rich, but expensive and risky. Still, they are powerful mechanisms for learning new concepts, developing creative and critical thinking, and above all social capital acquisition.
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| 986057. |
- Maric, Jasmina, 1968
(författare)
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Magnets
- 2022
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Ingår i: Interactions. - : Association for Computing Machinery (ACM). - 1072-5520 .- 1558-3449. ; 29:3, s. 10-11
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 986058. |
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| 986059. |
- Maric, Jovana, et al.
(författare)
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Prostaglandin E-2 suppresses human group 2 innate lymphoid cell function
- 2018
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Ingår i: Journal of Allergy and Clinical Immunology. - : MOSBY-ELSEVIER. - 0091-6749 .- 1097-6825. ; 141:5, s. 1761-1773.e6
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Tidskriftsartikel (refereegranskat)abstract
- Background: Group 2 innate lymphoid cells (ILC2s) are involved in the initial phase of type 2 inflammation and can amplify allergic immune responses by orchestrating other type 2 immune cells. Prostaglandin (PG) E-2 is a bioactive lipid that plays protective roles in the lung, particularly during allergic inflammation.Objective: We set out to investigate how PGE(2) regulates human ILC2 function.Methods: The effects of PGE(2) on human ILC2 proliferation and intracellular cytokine and transcription factor expression were assessed by means of flow cytometry. Cytokine production was measured by using ELISA, and real-time quantitative PCR was performed to detect PGE(2) receptor expression.Results: PGE(2) inhibited GATA-3 expression, as well as production of the type 2 cytokines IL-5 and IL-13, from human tonsillar and blood ILC2s in response to stimulation with a combination of IL-25, IL-33, thymic stromal lymphopoietin, and IL-2. Furthermore, PGE(2) downregulated the expression of IL-2 receptor alpha (CD25). In line with this observation, PGE(2) decreased ILC2 proliferation. These effects were mediated by the combined action of E-type prostanoid receptor (EP) 2 and EP4 receptors, which were specifically expressed on ILC2s.Conclusion: Our findings reveal that PGE(2) limits ILC2 activation and propose that selective EP2 and EP4 receptor agonists might serve as a promising therapeutic approach in treating allergic diseases by suppressing ILC2 function.
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| 986060. |
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