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- Kanai, M, et al.
(author)
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- 2023
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swepub:Mat__t
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- Niemi, MEK, et al.
(author)
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- 2021
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swepub:Mat__t
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- Beale, S. B., et al.
(author)
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Combined two-phase co-flow and counter-flow in a gas channel/porous transport layer assembly
- 2020. - 9
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In: PRiME 2020 : Polymer Electrolyte Fuel Cells and Electrolyzers 20 (PEFC and E 20) - Polymer Electrolyte Fuel Cells and Electrolyzers 20 (PEFC and E 20). - : The Electrochemical Society. - 1938-5862 .- 1938-6737. - 9781607685395 ; 98:9, s. 305-315
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Conference paper (peer-reviewed)abstract
- This paper considers a detailed numerical analysis of combined liquid-gas co-flow in a gas channel, with liquid-gas counter-flow in a porous transport layer, as is typically found on the cathode side of a polymer electrolyte fuel cell. The geometry is obtained by digital reconstruction of nano-computer tomography images. From this, the domain is tessellated with an unstructured castellated or octree mesh, upon which the equations of mass and momentum are solved by means of a volume of fluid method. Liquid water is produced from an electrode where gaseous oxygen is simultaneously consumed by electrochemical reduction; Liquid-gas counter flow in the porous transport layer results in liquid drops being entrained in co-flow in the gas channels and convected by the gas downstream.
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- Georgakis, Marios K., et al.
(author)
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Association of Circulating Monocyte Chemoattractant Protein-1 Levels with Cardiovascular Mortality : A Meta-analysis of Population-Based Studies
- 2021
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In: JAMA Cardiology. - : American Medical Association (AMA). - 2380-6583. ; 6:5, s. 587-592
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Journal article (peer-reviewed)abstract
- Importance: Human genetics and studies in experimental models support a key role of monocyte-chemoattractant protein-1 (MCP-1) in atherosclerosis. Yet, the associations of circulating MCP-1 levels with risk of coronary heart disease and cardiovascular death in the general population remain largely unexplored. Objective: To explore whether circulating levels of MCP-1 are associated with risk of incident coronary heart disease, myocardial infarction, and cardiovascular mortality in the general population. Data Sources and Selection: Population-based cohort studies, identified through a systematic review, that have examined associations of circulating MCP-1 levels with cardiovascular end points. Data Extraction and Synthesis: Using a prespecified harmonized analysis plan, study-specific summary data were obtained from Cox regression models after excluding individuals with overt cardiovascular disease at baseline. Derived hazard ratios (HRs) were synthesized using random-effects meta-analyses. Main Outcomes and Measures: Incident coronary heart disease (myocardial infarction, coronary revascularization, and unstable angina), nonfatal myocardial infarction, and cardiovascular death (from cardiac or cerebrovascular causes). Results: The meta-analysis included 7 cohort studies involving 21401 individuals (mean [SD] age, 53.7 [10.2] years; 10012 men [46.8%]). Mean (SD) follow-up was 15.3 (4.5) years (326392 person-years at risk). In models adjusting for age, sex, and race/ethnicity, higher MCP-1 levels at baseline were associated with increased risk of coronary heart disease (HR per 1-SD increment in MCP-1 levels: 1.06 [95% CI, 1.01-1.11]; P =.01), nonfatal myocardial infarction (HR, 1.07 [95% CI, 1.01-1.13]; P =.02), and cardiovascular death (HR, 1.12 [95% CI, 1.05-1.20]; P <.001). In analyses comparing MCP-1 quartiles, these associations followed dose-response patterns. After additionally adjusting for vascular risk factors, the risk estimates were attenuated, but the associations of MCP-1 levels with cardiovascular death remained statistically significant, as did the association of MCP-1 levels in the upper quartile with coronary heart disease. There was no significant heterogeneity; the results did not change in sensitivity analyses excluding events occurring in the first 5 years after MCP-1 measurement, and the risk estimates were stable after additional adjustments for circulating levels of interleukin-6 and high-sensitivity C-reactive protein. Conclusions and Relevance: Higher circulating MCP-1 levels are associated with higher long-term cardiovascular mortality in community-dwelling individuals free of overt cardiovascular disease. These findings provide further support for a key role of MCP-1-signaling in cardiovascular disease..
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10. |
- Andersson, M., et al.
(author)
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Coupling of lattice boltzmann and volume of fluid approaches to study the droplet behavior at the gas diffusion layer/gas channel interface
- 2018. - 13
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In: ECS Transactions. - : The Electrochemical Society. - 1938-6737 .- 1938-5862. - 9781607688600 ; 86, s. 329-336
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Conference paper (peer-reviewed)abstract
- A typical polymer electrolyte fuel cell (PEFC) flow field consists of micro/minichannels. The continues removal of liquid water from the cathode channels is a critical topic, as water droplets forming in the channels may block the transport of gaseous oxygen to the active sites, which not only gives an uneven current distribution and substantial loss of performance, but also, increases degradation rates and unstable operation. Water generated by the electrochemical reactions condenses, depending on temperature mainly, into liquid form, potentially flooding various part of the PEFC. The aim of this work is to obtain an increased understanding of the droplet behavior at the gas diffusion layer (GDL) interface with the gas channels in PEFCs by the coupling of Lattice Boltzmann (LB) and Volume of Fluid (VOF) approaches. A multiscale environment is established with input parameters in the VOF model being extracted from in-house LB calculations. It is clear that the contact angle as well as the size of the liquid droplet vary with positions at the GDL surface, depending on the stochastic GDL geometry. A VOF model describing one straight channel with one gas inlet, one liquid inlet (at the GDL surface) and one two-phase outlet is employed.
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