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- Ahlsson, Anders J., et al.
(författare)
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Postoperative atrial fibrillation is not correlated to C-reactive protein
- 2007
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Ingår i: Annals of Thoracic Surgery. - : Elsevier BV. - 0003-4975 .- 1552-6259. ; 83:4, s. 1332-1337
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The peak incidence of postoperative atrial fibrillation (AF) occurs around the second postoperative day, a time at which serum inflammatory markers are elevated. The aim of this study was to investigate differences between patients with and without postoperative AF with special regard to C-reactive protein (CRP) serum levels. METHODS: The study cohort included all heart surgery patients who had sinus rhythm preoperatively, survived postoperative day 3, and were operated on between July 1, 2004, and June 30, 2005 (n = 524). Any episode of AF during the first 7 postoperative days defined the patient as belonging to the postoperative AF group. Creatine kinase-myocardial band (CK-MB) was measured at postoperative day 1, and CRP was measured preoperatively and at postoperative day 3. Risk factors for postoperative AF were determined using bivariate and multivariate regression analysis. RESULTS: Of 524 patients, 182 had at least one episode of AF (34.7%). Preoperative and postoperative CRP concentrations did not differ between the groups (postoperative CRP 175.4 +/- 64.4 versus 175.3 +/- 60.1 mg/L respectively, p = 0.99). Atrial fibrillation patients were significantly older (p < 0.001) and had higher CK-MB levels (33.6 +/- 53.1 microg/L versus 22.5 +/- 26.7 microg/L, respectively, p = 0.009). The odds ratio for postoperative AF with postoperative CK-MB greater than 70 microg/L was 3.5 (confidence interval: 1.4 to 8.6). CONCLUSIONS: Postoperative AF has no correlation to the inflammatory marker CRP in heart surgery patients. Ischemic myocardial injury might predispose for postoperative AF.
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| 5. |
- von Kraemer, Sophie, et al.
(författare)
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Evaluation of TiO2 as catalyst support in Pt-TiO2/C composite cathodes for the proton exchange membrane fuel cell
- 2008
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753 .- 1873-2755. ; 180:1, s. 185-190
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Tidskriftsartikel (refereegranskat)abstract
- Anatase TiO2 is evaluated as catalyst support material in authentic Pt-TiO2/C composite gas diffusion electrodes (GDEs), as a different approach in the context of improving the proton exchange membrane fuel cell (PEMFC) cathode stability. A thermal stability study shows high carbon stability as Pt nanoparticles are supported on TiO2 instead of carbon in the Pt-TiO2/C composite material, presumably due to a reduced direct contact between Pt and C. The performance of Pt-TiO2/C cathodes is investigated electrochemically in assembled membrane-electrode assemblies (MEAs) considering the added carbon fraction and Pt concentration deposited on TiO2. The O-2 reduction current for the Pt-TiO2 alone is expectedly low due to the low electronic conductivity in bulk TiO2. However, the Pt-TiO2/C composite cathodes show enhanced fuel cell cathode performance with growing carbon fraction and increasing Pt concentration deposited on TiO2. The proposed reasons for these observations are improved macroscopic and local electronic conductivity, respectively. Electron micrographs of fuel cell tested Pt-TiO2/C composite cathodes illustrate only a minor Pt migration in the Pt-TiO2/C structure, in which anatase TiO2 is used as Pt support. On the whole, the study demonstrates a stable Pt-TiO2/C Composite material possessing a performance comparable to conventional Pt-C materials when incorporated in a PEMFC cathode.
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| 6. |
- Wikander, Kjell, et al.
(författare)
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Alternative catalysts and carbon support material for PEMFC
- 2006
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Ingår i: Fuel Cells. - : Wiley. - 1615-6846 .- 1615-6854. ; 6:1, s. 21-25
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Tidskriftsartikel (refereegranskat)abstract
- In order to investigate the possibility of increasing the reactivity for oxygen reduction reaction (ORR) of the cathode in a PEMFC a series of Pt/C catalysts was prepared using water-in-oil microemulsions for synthesizing Pt nanoparticles. The Pt nanoparticles were deposited on porous carbon support (Vulcan XC-72 or a mesoporous carbon) and the catalysts were processed into MEAs. The MEA samples were evaluated and compared with a commercial sample and with Pt/C catalyst samples prepared using a conventional direct impregnation method. The mesoporous carbon support investigated as a potential alternative to Vulcan XC72 has a very high specific surface area and a narrow pore size distribution. The materials were characterized with XRD, TEM, SEM-EDX, N-2 sorption and steady state polarization. It was found that it is possible to increase the ORR reactivity using the microemulsion route for formation of Pt nanoparticles. It was concluded that the MEA processing conditions for the mesoporous carbon support have to be modified to reach improved ORR reactivity, likely due to the large differences in specific surface area, porosity and conductivity compared to the Vulcan carbon.
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| 8. |
- Ajpi, Cesario, et al.
(författare)
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Crystal structure and Hirshfeld surface analysis of poly[tris(mu(4)-benzene-1,4-dicarboxylato)tetrakis(di-methylformamide)tr inickel(II)] : a two-dimensional coordination network
- 2019
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Ingår i: Acta Crystallographica Section E. - : International Union of Crystallography. - 2056-9890. ; 75, s. 1839-1843
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Tidskriftsartikel (refereegranskat)abstract
- The crystal structure of the title compound, [Ni-3(C8H4O4)(3)(C3H7NO)(4)], is a two-dimensional coordination network formed by trinuclear linear Ni-3(tp)(3)(DMF)(4) units (tp = terephthalate = benzene-1,4-dicarboxylate and DMF = dimethyl-formamide) displaying a characteristic coordination mode of acetate groups in polynuclear metal-organic compounds. Individual trinuclear units are connected through tp anions in a triangular network that forms layers. One of the DMF ligands points outwards and provides interactions with equivalent planes above and below, leaving the second ligand in a structural void much larger than the DMF molecule, which shows positional disorder. Parallel planes are connected mainly through weak C-H center dot center dot center dot O, H center dot center dot center dot H and H center dot center dot center dot C interactions between DMF molecules, as shown by Hirshfeld surface analysis.
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| 9. |
- Ajpi, Cesario, et al.
(författare)
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Crystal structure and Hirshfeld surface analysis of poly[tris-(μ4-benzene-1,4-di-carboxyl-ato)tetra-kis-(di-methyl-formamide)-trinickel(II)] : a two-dimensional coordination network.
- 2019
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Ingår i: Acta Crystallographica Section E. - 2056-9890. ; 75:Pt 12, s. 1839-1843
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Tidskriftsartikel (refereegranskat)abstract
- The crystal structure of the title compound, [Ni3(C8H4O4)3(C3H7NO)4], is a two-dimensional coordination network formed by trinuclear linear Ni3(tp)3(DMF)4 units (tp = terephthalate = benzene-1,4-di-carboxyl-ate and DMF = di-methyl-formamide) displaying a characteristic coordination mode of acetate groups in polynuclear metal-organic compounds. Individual trinuclear units are connected through tp anions in a triangular network that forms layers. One of the DMF ligands points outwards and provides inter-actions with equivalent planes above and below, leaving the second ligand in a structural void much larger than the DMF mol-ecule, which shows positional disorder. Parallel planes are connected mainly through weak C-H⋯O, H⋯H and H⋯C inter-actions between DMF mol-ecules, as shown by Hirshfeld surface analysis.
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| 10. |
- Ajpi Condori, Cesario, 1978-
(författare)
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Hybrid materials for lithium-ion batteries
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Lithium‐ion batteries are the most important power source for electronic devices as electronics, storage and the different electric vehicles. The research and development of new materials for different applications has increased, especially in the development of materials with better electrochemical properties (Specific capacity, rate capability, high energy density and cyclability). Inorganic materials such as LiFePO4, LiMn2O4 and organic materials such as Li4C6O6, quinones and anthraquinones, polyaniline (PANI) and others have been extensively studied. Improvement of the electrochemical properties involve different aspects as: control in the particle size of the materials, doping with other elements and the combination of the different properties of the organic an inorganic materials. The development of hybrids materials with improved electrochemical properties need a combination between of inorganic and organic structures. This type of hybrids materials are a very attractive option for the development of advanced materials. For the design of this type of hybrid materials it is necessary to form interactions between the inorganic and organic part (supramolecular chemistry). This opens up for using an immense amount of organic materials such as conductive polymers and PANI (Polyaniline) are attractive alternatives in the development of hybrid materials due to their excellent electronic conductivity. Other attractive types of hybrid materials are compounds based on metal-organic frameworks (MOF), coordination polymers (CP) and coordination networks (CN).This thesis work is focused in the synthesis, structural characterization and electrochemical characterization of two groups of hybrid materials: 1) LiFePO4-PANI synthetized by different methods.2) Metal-organic compounds M-BDC-DMF with M=Ni2+, Fe2+, C8H4O2=Terephthalate=BDC=Benzene dicarboxylate, DMF=N,N-dimethylformamide.The materials were synthesized by chemical oxidation methods combined with thermal treatment (LiFePO4-PANI-Li hybrid powder) and by solvothermal methods (M-BDC-DMF). The materials were characterized by SCXRD, PXRD, FTIR, SEM and electrochemical methods and the electrochemical characterization was carried out using CV, EIS and galvanostatics methods. The specific capacities of PANI was 95 mAh/g, of LiFePO4 was 120 mAh/g and of LiFePO4-PANI was 145 mAh/g at 0.1C. At 2C the capacity of LiFePO4 was 70 mAh/g and LiFePO4-PANI was 100 mAh/g. The specific capacities of Ni3(C8H4O4)3(C3H7NO)4 is ~50 mAh/g and Fe-BDC-DMF was ~175 mAh/g. The work has shown that PANI can improve the performance of LFP also at higher discharges rates. For M-BDC-DMF stability seems to be an issue which should be studied more in the future.
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