| 1. |
- Chen, Yuxi, et al.
(författare)
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Magnetohydrodynamic With Embedded Particle-In-Cell Simulation of the Geospace Environment Modeling Dayside Kinetic Processes Challenge Event
- 2020
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Ingår i: Earth and Space Science. - : American Geophysical Union (AGU). - 2333-5084. ; 7:11
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Tidskriftsartikel (refereegranskat)abstract
- We use the magnetohydrodynamic (MHD) with embedded particle-in-cell model (MHD-EPIC) to study the Geospace Environment Modeling (GEM) dayside kinetic processes challenge event at 01:50-03:00 UT on 18 November 2015, when the magnetosphere was driven by a steady southward interplanetary magnetic field (IMF). In the MHD-EPIC simulation, the dayside magnetopause is covered by a PIC code so that the dayside reconnection is properly handled. We compare the magnetic fields and the plasma profiles of the magnetopause crossing with the MMS3 spacecraft observations. Most variables match the observations well in the magnetosphere, in the magnetosheath, and also during the current sheet crossing. The MHD-EPIC simulation produces flux ropes, and we demonstrate that some magnetic field and plasma features observed by the MMS3 spacecraft can be reproduced by a flux rope crossing event. We use an algorithm to automatically identify the reconnection sites from the simulation results. It turns out that there are usually multiple X-lines at the magnetopause. By tracing the locations of the X-lines, we find that the typical moving speed of the X-line endpoints is about 70 km/s, which is higher than but still comparable with the ground-based observations.
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| 2. |
- Jang, David H., et al.
(författare)
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Alterations in cerebral and cardiac mitochondrial function in a porcine model of acute carbon monoxide poisoning
- 2021
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Ingår i: Clinical Toxicology. - : Informa UK Limited. - 1556-3650 .- 1556-9519. ; 59:9, s. 801-809
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The purpose of this study is the development of a porcine model of carbon monoxide (CO) poisoning to investigate alterations in brain and heart mitochondrial function. Design: Two group large animal model of CO poisoning. Setting: Laboratory. Subjects: Ten swine were divided into two groups: Control (n = 4) and CO (n = 6). Interventions: Administration of a low dose of CO at 200 ppm to the CO group over 90 min followed by 30 min of re-oxygenation at room air. The Control group received room air for 120 min. Measurements: Non-invasive optical monitoring was used to measure cerebral blood flow and oxygenation. Cerebral microdialysis was performed to obtain semi real time measurements of cerebral metabolic status. At the end of the exposure, both fresh brain (cortical and hippocampal tissue) and heart (apical tissue) were immediately harvested to measure mitochondrial respiration and reactive oxygen species (ROS) generation and blood was collected to assess plasma cytokine concentrations. Main results: Animals in the CO group showed significantly decreased Complex IV-linked mitochondrial respiration in hippocampal and apical heart tissue but not cortical tissue. There also was a significant increase in mitochondrial ROS generation across all measured tissue types. The CO group showed a significantly higher cerebral lactate-to-pyruvate ratio. Both IL-8 and TNFα were significantly increased in the CO group compared with the Control group obtained from plasma. While not significant there was a trend to an increase in optically measured cerebral blood flow and hemoglobin concentration in the CO group. Conclusions: Low-dose CO poisoning is associated with early mitochondrial disruption prior to an observable phenotype highlighting the important role of mitochondrial function in the pathology of CO poisoning. This may represent an important intervenable pathway for therapy and intervention.
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| 3. |
- Lin, Hongzhen, et al.
(författare)
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Collective Fluorescence Blinking in Linear J-Aggregates Assisted by Long-Distance Exciton Migration.
- 2010
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 10:2, s. 620-626
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Tidskriftsartikel (refereegranskat)abstract
- Fluorescence blinking corresponding to collective quenching of up to 100 dye monomers is reported for individual J-aggregates of a perylene bisimide (PBI) dye. This implies an exciton diffusion length up to 70 nm in these one-dimensional assemblies. The number of quenched monomers was directly measured by comparing the fluorescence brightness of the J-aggregates with that of noncoupled PBI molecules. This brightness analysis technique is useful for unraveling photophysical parameters of any individual fluorescent nanosystem.
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| 4. |
- Lin, Hongzhen, et al.
(författare)
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Fate of Excitations in Conjugated Polymers : Single-Molecule Spectroscopy Reveals Nonemissive "Dark" Regions in MEH-PPV Individual Chains
- 2009
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Ingår i: Nano letters (Print). - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 9:12, s. 4456-4461
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Tidskriftsartikel (refereegranskat)abstract
- Single chains of the conjugated polymer MEH-PPV (poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene)) were studied with wide-field fluorescence microscopy (dispersion in inert polymer matrices) and with fluorescence correlation spectroscopy (chloroform solution). The fluorescence yield of individual molecules in matrices was found to be 1-2 orders of magnitude lower than that in solution and it decreased substantially with increasing chain length. It suggests that isolation of MEH-PPV molecules in polymer matrices creates favorable conditions for photogeneration of nonemissive primary excited states.
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| 5. |
- Piel, Sarah, et al.
(författare)
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Effect of dimethyl fumarate on mitochondrial metabolism in a pediatric porcine model of asphyxia-induced in-hospital cardiac arrest
- 2024
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Ingår i: Scientific Reports. - 2045-2322. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Neurological and cardiac injuries are significant contributors to morbidity and mortality following pediatric in-hospital cardiac arrest (IHCA). Preservation of mitochondrial function may be critical for reducing these injuries. Dimethyl fumarate (DMF) has shown potential to enhance mitochondrial content and reduce oxidative damage. To investigate the efficacy of DMF in mitigating mitochondrial injury in a pediatric porcine model of IHCA, toddler-aged piglets were subjected to asphyxia-induced CA, followed by ventricular fibrillation, high-quality cardiopulmonary resuscitation, and random assignment to receive either DMF (30 mg/kg) or placebo for four days. Sham animals underwent similar anesthesia protocols without CA. After four days, tissues were analyzed for mitochondrial markers. In the brain, untreated CA animals exhibited a reduced expression of proteins of the oxidative phosphorylation system (CI, CIV, CV) and decreased mitochondrial respiration (p < 0.001). Despite alterations in mitochondrial content and morphology in the myocardium, as assessed per transmission electron microscopy, mitochondrial function was unchanged. DMF treatment counteracted 25% of the proteomic changes induced by CA in the brain, and preserved mitochondrial structure in the myocardium. DMF demonstrates a potential therapeutic benefit in preserving mitochondrial integrity following asphyxia-induced IHCA. Further investigation is warranted to fully elucidate DMF’s protective mechanisms and optimize its therapeutic application in post-arrest care.
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