| 1. |
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| 2. |
- Abdel-Motal, Ussama M., et al.
(författare)
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Major histocompatibility complex class I binding glycopeptides for the estimation of 'empty' class I molecules
- 1995
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Ingår i: Journal of Immunological Methods. - : Elsevier BV. - 0022-1759. ; 188:1, s. 21-31
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Tidskriftsartikel (refereegranskat)abstract
- Different forms of major histocompatibility complex (MHC) class I heavy chains are known to be expressed on the cell surface, including molecules which are functionally 'empty'. Direct peptide binding to cells is obvious during sensitization of target cells in vitro for cytotoxic T lymphocyte killing and 'empty' MHC-I molecules are comparatively abundant on TAP- 1 2 peptide transporter mutant cells. In the present work we have estimated the fraction of 'empty' MHC class I molecules using glycosylated peptides and cellular staining with carbohydrate specific monoclonal antibodies. Synthetic Db and Kb binding peptides were coupled at different positions with different di- or trisaccharides, using different spacing between the carbohydrate and the peptide backbone. Binding of sugar specific mAbs was compared in ELISA and cellular assays. An optimal Db binding glycopeptide was used for comparative staining with anti-Db and anti-carbohydrate monoclonal antibodies to estimate fractions of 'empty' molecules on different T lymphoid cells. On activated normal T cells, a large fraction of Db molecules were found to be 'empty'. The functional cole of such 'empty' MHC class I molecules on T cells is presently unclear. However, on antigen presenting cells they might participate in the antigen presentation process.
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| 3. |
- Abelius, Martina, 1980-
(författare)
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Immunological interactions between mother and child during pregnancy in relation to the development of allergic diseases in the offspring
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Pregnancy and allergic disease have both been postulated as T-helper 2 (Th2) phenomena. Thus, the increased propensity of allergic mothers to mount Th2-responses might generate favourable effects on the maintenance of pregnancy, but might also be unfavorable, as fetal exposure to a strong Th2 environment could influence the immune development in the offspring to a Th2-like phenotype, favouring IgE production and possibly allergy development later in life. The influence of the intrauterine environment on the immunity and allergy development in the offspring needs to be further investigated.Aim: The aim of this thesis was to explore the Th1/Th2 balance in allergic and non-allergic women during pregnancy and its influence on the shaping of the Th1/Th2 profile in the neonate and the development of allergic diseases in the offspring.Material and methods: The study group included 20 women with and 36 women without allergic symptoms followed during pregnancy (gestational week 10-12, 15-16, 25, 35, 39) and 2 and 12 months postpartum, and their children followed from birth to 6 years of age. The circulating Th1-like chemokines CXCL9, CXCL10, CXCL11, Th2-like chemokines CCL17, CCL18 and CCL22, and the allergen-induced secretion of interleukin-4 (IL-4), IL-5, IL-10, IL-13, Interferon-γ (IFN-γ), CXCL10 and CCL17 were measured by Luminex and ELISA. The allergen-specific and total IgE levels were quantified using ImmunoCAP Technology. mRNA expression of Th1-, Th2-, Treg- and Th17-associated genes were measured by PCR arrays and real-time PCR.Results: We found that sensitised women with allergic symptoms had increased total IgE levels and birch- and cat-induced IL-5, IL-13 and CCL17 responses during pregnancy as compared with postpartum. The non-sensitised women without allergic symptoms had elevated cat-induced IL-5 and IL-13 responses and lower birch- and cat-induced IFN-γ during pregnancy, but similar IgE levels as compared with postpartum.Maternal total IgE levels during and after pregnancy correlated with cord blood (CB) IgE and CCL22 levels (regardless of maternal allergy status). Circulating CXCL11, CCL18 and CCL22 levels during pregnancy and postpartum correlated with the corresponding chemokine levels in the offspring at various time points during childhood. Maternal IL-5 expression in peripheral blood mononuclear cells (PBMC) was associated with neonatal Galectin-1, and placental p35 expression was negatively associated with neonatal Tbx21 expression. Increased mRNA expression of CCL22 in cord blood mononuclear cells (CBMC), and increased CCL17 and CCL22 levels in CB were observed in children later developing allergic symptoms and sensitisation as compared with children who did not. Development of allergic symptoms and sensitisation were associated with increased total IgE, CCL17, CCL18 and CCL22 levels during childhood.Conclusions: Maternal allergy was associated with a pronounced Th2 deviation during pregnancy, shown as increased total IgE levels and birch- and cat-induced IL-5, IL-13 and CCL17 responses during pregnancy, possibly exposing their fetuses to a particular strong Th2 environment during gestation.Correlations were shown between the maternal immunity during pregnancy and the offspring’s immunity at birth and later during childhood, indicating an interplay between the maternal and fetal immunity.Allergy development during the first 6 years of life was associated with a marked Th2 deviation at birth and a delayed down-regulation of this Th2-skewed immunity during childhood.
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| 4. |
- Aldén, Liselotte, et al.
(författare)
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Nedmontering av vindkraftverk och efterbehandling av platsen
- 2014
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Rapport (populärvet., debatt m.m.)abstract
- Dennarapport haranalyseratoch jämförtlagar, historia och tillstånd om nedmontering och dess kostnader samtolika alternativ för borttagandet och efterbehandlingav plats iSverigeoch i andra länder.Lagar och regelverk om nedmonteringundersöktes för land-och havsbaserad vindkraft i flera länder. Särskild uppmärksamhet har ägnats åt krav på ekonomisk säkerhet för efterbehandlingoch nedmontering i dessa länder. Ingen av de granskade länderna hade exakt samma krav, men det fanns likheter i vem som bestämde kraven och om en ekonomisk säkerhet föreskrivs.Rapporten har undersöktvindkraftsavvecklingeniSverigeochDanmarkochenkostnadsstudieav nedmonteringar iSverige, DanmarkochUSAhar genomförts. Kostnadsstudienbehandlarolikamoment vidnedmontering och efterbehandlingsamt olika grader av efterbehandling. Studiens resultattyder på attvindkraftverkens installerade effekt, lokaliseringochgradavefterbehandlingharstörst påverkanpåden totala kostnaden förnedmontering och efterbehandling.Hanteringen av vindkraftverk efter nedmontering och alternativ för borttagande av vindkrafts-komponenterna har granskats. Idag finns tre alternativ för vindkraftverk efter nedmontering: renovering, återförsäljning eller återvinning. Renovering av komponenterna i ett vindkraftverk kan potentiellt förlänga deras livslängd, men kan begränsas av eventuella kostnader, tillförlitlighet och tillgänglighet. Återförsäljning av vindkraftverk för fortsatt användning är ett realistiskt alternativ men det krävs att det finns en efterfrågan. Återvinningsvärdet är beroende på storlek och typ av skrot och aktuellametallpriser. För övrigt kan vissa komponenter inte återvinnas på ett ekonomiskt försvarbart sätt i dag, främst rotorbladen.Kravenpå ekonomisk säkerhet för efterbehandlingochnedmonteringitillstånds-och anmälningsärendeniSverigeunder åren 2010-2012har undersökts. I nästanalla tillståndsbeslutkrävsen ekonomisksäkerhet för nedmontering och efterbehandling. Storleken på säkerhet varierade stort, menett specifikt säkerhetsbelopppå 300000 kronoranvändesiettstortantaltillstånd. Kraven på efterbehandlingsgraditillståndsbeslutenvaroftastallmänt formulerade ochnästansamtliga var delegerade till tillsynsmyndighetenatt fastställaden slutligaefterbehandlingsgraden. Majoriteten avbesluteni anmälningsärendeninnehöllliknande återställningskravsom itillståndsbesluten,menenligt lagkan deinteinnehållaenekonomisk säkerhetpå samma sätt som för tillståndspliktiga vindkraftverk.Enjämförelse av antalet vindkraftverk med tillstånds-och anmälningsbeslutefterlagändringen2009har utförtsmen eftersom data inte var tillförlitligahar ingen trendellerprognospresenterats. Rapporten avslutasmed att konstatera att det är en stor variation påregler och kravide studerade länderna. Slutsatsennoteraräven de specifikaresultatenfrånfallstudien ochfrån granskningenavtillstånds-ochanmälningsbesluten. Resultatenjämförs ochtvåområden har identifieratsför framtidafördjupaddiskussion, nämligenstorleken på ekonomisk säkerhetochnär ochvem som skabestämma graden av efterbehandling.
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| 5. |
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| 7. |
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| 8. |
- Broberg, Marita, 1973, et al.
(författare)
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Cell swelling precedes seizures induced by inhibition of astrocytic metabolism.
- 2008
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Ingår i: Epilepsy Res.. - : Elsevier BV. - 0920-1211. ; 80:2-3, s. 132-41
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Tidskriftsartikel (refereegranskat)abstract
- It is currently unknown what processes take place at the interface between non-ictal and ictal activity during seizure initiation. In this study, using paralysed awake rats, we focally inhibited astrocytic metabolism with fluorocitrate (FC), causing seizures. We measured changes in electroencephalogram (EEG) (0-300 Hz), and extracellular ion-concentrations during ictal onsets defining possible relationships with impedance-determined cell swelling. In animals showing ictal activity (69%) there were spike-wave discharges, spike-wave discharges followed by spreading depression and spreading depression without any discharges. In a high proportion of spike-wave discharges (>95%), just prior to the first spike-wave discharge, there was a decrease in the volume of the extracellular space. Following the initiation of cell swelling and prior to discharges, there were increases in high-frequency (150-300 Hz) EEG activity, increases in extracellular potassium- and decreases in extracellular calcium-concentrations. We suggest that EEG and ionic changes are not causative of cell swelling. Cell swelling due to metabolic failure in astrocytes at the injected site may release excitatory amino acids. At the same time, our results suggest ion homeostasis is not maintained and increased neuronal excitability and synchronisation occur. These could be the drivers changing normal brain activity into ictal activity.
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| 9. |
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| 10. |
- Creaser, Derek, 1966, et al.
(författare)
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Kinetic modeling of autothermal reforming of dimethyl ether
- 2010
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 49:20, s. 9712-9719
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Tidskriftsartikel (refereegranskat)abstract
- A global kinetic model was developed for the autothermal reforming of dimethyl ether (DME) over a Pd-Zn/Al2O3 catalyst on a cordierite monolith. A kinetic model consisting of five key overall reactions was found to capture the main features of experimental data. The modeling also accounted for heat transport effects in the reactor that are of importance when coupling the exothermic oxidation reactions with endothermic steam reforming reactions. The modeling confirmed that oxidation reactions dominate near the inlet of the reactor, generating a local hot spot. The heat from oxidation reactions accelerates the reforming reactions. Water adsorption was found to have a weak detrimental influence on the activity. Based on the model, the influence of the reactor scale and oxygen supply by air feed on the performance of the reactor was examined.
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| 11. |
- Dahlin, Sandra, et al.
(författare)
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Multivariate analysis of the effect of biodiesel-derived contaminants on V2O5-WO3/TiO2 SCR catalysts
- 2016
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Ingår i: Applied Catalysis B. - : Elsevier. - 0926-3373 .- 1873-3883. ; 183, s. 377-385
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates the effect of biodiesel-derived contaminants on vanadia-based NH3-SCR catalysts in heavy-duty exhaust aftertreatment. The aim was to study, not only the effect of single contaminants on the catalyst performance, but also of possible interaction effects between poisons.The effect of six potential catalyst poisons (Na, K, Mg, P, S and Zn) was evaluated using an experimental design and multivariate data analysis. Monolithic V2O5-WO3/TiO2 catalysts were subjected to accelerated laboratory-scale aging, where the six contaminants were fed simultaneously using a wet impregnation method. In addition to NOx conversion tests, the catalysts were characterized by means of ICP-OES, SEM-EDX, XPS, N2 physisorption and NH3-TPD. The lab-aged samples were compared to fresh and vehicle-aged catalysts.The accelerated aging method showed good reproducibility and gave rise to surface compounds similar to those found in vehicle-aged catalysts. Despite plausible differences regarding penetration depth of the contaminants into the walls of the catalyst, the aging method appears to be an efficient way to point out significant chemical poisons.The model obtained from the experimental design was found to correlate well with the experimental data and can therefore be used to predict effects of the various poisons and poison interactions. Significant effects on the NO. x conversion were found for P, S, Na, Mg and K as well as for the interactions P. ×. Na, P. ×. K and S. ×. Na. A poisoning effect was found for Mg, Na, K, P. ×. K, and P. ×. Na, where Na and K exhibited the strongest poisoning effect. The deactivating effect of alkali was lowered in the presence of phosphorus and sulfur, which is explained by the formation of phosphates and sulfates, preventing the interaction of the alkali metals with the vanadia active sites.
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| 12. |
- Farouk, Salah E, et al.
(författare)
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Gamma delta T cells inhibit in vitro growth of the asexual blood stages of Plasmodium falciparum by a granule exocytosis-dependent cytotoxic pathway that requires granulysin.
- 2004
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Ingår i: European Journal of Immunology. - : Wiley. - 0014-2980 .- 1521-4141. ; 34:8, s. 2248-56
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Tidskriftsartikel (refereegranskat)abstract
- Several reports have stated the ability of gamma delta T cells to inhibit the growth of the asexual blood stages of Plasmodium falciparum in vitro. However, little information is available about the mechanisms involved. In this study, in vitro systems were used to study the role of the granule exocytosis-dependent cytotoxic pathway in the growth inhibition/killing of P. falciparum by human gamma delta T cells. Our results show that the inhibition requires cell-to-cell contact and that gamma delta T cells kill the asexual blood stages of P. falciparum through a granule exocytosis-dependent cytotoxic pathway after recognition of certain ligands or molecules expressed on the surface of infected erythrocytes or merozoites. The in vitro inhibitory capacity of gamma delta T cells was strongly correlated with the expression of granulysin in the cytotoxic granules, while non-inhibitory CD4+ and CD8+ T cells expressed very little, implicating a role for granulysin in parasite inhibition. This was further suggested by the addition of neutralizing anti-granulysin antibodies, which abrogated the parasite inhibitory capacity of the gamma delta T cells. Taken together, our results suggest that the capacity of gamma delta T cells for inhibition/killing of P. falciparum is based on the granule exocytosis-dependent cytotoxic pathway and that the presence of granulysin is essential to maintain efficient killing.
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| 13. |
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| 14. |
- Granestrand, Jonas, 1988-, et al.
(författare)
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Assessment of the impact of trace elements in FAME biodiesel on diesel oxidation catalyst activity after full lifetime of operation in a heavy-duty truck
- 2024
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Ingår i: Applied Catalysis B. - Amsterdam : Elsevier. - 0926-3373 .- 1873-3883.
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Tidskriftsartikel (refereegranskat)abstract
- FAME biodiesel contains some trace amounts of Na, K, P, Ca and Mg. A diesel oxidation catalyst that had been used for an entire regulatory lifetime in a heavy-duty truck was studied, to investigate whether the presence of such trace elements poisons the catalyst. The vehicle-aged catalyst contained high loadings of S, P and Na, as well as a visible layer of soot. Activity in the NO oxidation reaction was severely decreased compared to a fresh catalyst of the same type, while the CO and C3H6 oxidation reactions were less affected. Activity testing after subsequent selective trace element removal procedures was used to decouple the effect of different poisons. Sintering was observed to be the main cause of catalyst deactivation. Of the trace elements present on the catalyst, P had the largest effect on catalyst activity, while the other trace elements had little effect.
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| 15. |
- Granestrand, Jonas, et al.
(författare)
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Assessment of the Impact of Trace Elements in FAME Biodiesel on Diesel Oxidation Catalyst Activity after Full Lifetime of Operation in A Heavy-Duty Truck
- 2020
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Ingår i: Catalysts. - : MDPI AG. - 2073-4344. ; 10:12
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Tidskriftsartikel (refereegranskat)abstract
- Fatty acid methyl ester (FAME) biodiesel contains some trace amounts of Na, K, P, Ca, and Mg. Our objective was to investigate whether the presence of such elements can poison a diesel oxidation catalyst that has been used for an entire regulatory lifetime in a heavy-duty truck fueled by FAME biodiesel. The investigated vehicle-aged catalyst contained high loadings of S, P, and Na, as well as a visible layer of soot. Activity in the NO oxidation reaction was severely decreased compared to a fresh catalyst of the same type, while the CO and C3H6 oxidation reactions were less affected. Subsequent selective trace element removal procedures, followed by activity tests, were used to decouple the effect of different poisons. Sintering was observed to be the main cause of catalyst deactivation. Of the trace elements present on the catalyst, P had the greatest effect on catalyst activity, while the other trace elements had little effect.
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| 16. |
- Granestrand, Jonas, 1988-, et al.
(författare)
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Catalytic aftertreatment systems for trucks fueled by biofuels – aspects on the impact of fuel quality on catalyst deactivation
- 2018
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Ingår i: RSC Catalysis. - London : Royal Society of Chemistry. - 0140-0568 .- 1465-1920. ; 30, s. 64-145, s. 64-145
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Tidskriftsartikel (refereegranskat)abstract
- The issue of sustainable energy supply is a global problem for pursuing future endeavours in the energy area. In countries such as China and India there is a tremendous growth at the moment, which is envisaged by an ever growing demand for vehicles. Hence, one of the grand challenges of society is to meet the demands for sustainable and environmentally-friendly technologies in the transport sector. One way to tackle the problem of growing concentrations of carbon dioxide, which is believed to contribute to global warming, is the use of biofuels. It is becoming more and more evident that global warming is partly due to increasing anthropogenic carbon dioxide emissions. An important contribution to these emissions is the use of fossil fuels in the transport sector. Hence, more efficient engines and an increased use of biofuels would be a step in the right direction. Although new propulsion systems are emerging, such as hybrid power-trains and fuel cell systems, analysis shows that combustion systems with excess oxygen, such as the diesel engine, will be the most important engine concept for the next 20 years. In this paper we will identify the specific challenges related to the production and use of biofuels in heavy-duty trucks and how they influence the catalytic units in the emission after-treatment system in the truck. Biofuels, such as biodiesel, contain potential poisons for the vehicle exhaust after-treatment, such as potassium, sodium, magnesium, phosphorus, zinc, sulfur and other compounds.
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| 17. |
- Granlund, Moa Z., 1983-, et al.
(författare)
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Evaluation of Co, La, and Mn promoted Rh catalysts for autothermal reforming of commercial diesel
- 2014
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Ingår i: Applied Catalysis B. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 154, s. 386-394
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this paper was to study the influence three promoters (Co, La, Mn) had on the catalytic activity of Rh-based catalysts for autothermal reforming of diesel. The catalysts were supported on CeO2ZrO2 and the loading was 1 wt.% Rh and 6 wt.% promoter. The catalytic activity was evaluated in a monolith bench scale reactor with Swedish Environmental diesel, MK1. The process parameters employed at the ATR experiments were; O-2/C similar to 0.45, H2O/C similar to 2.5 and GHSV similar to 50,000h(-1), meanwhile the reactor temperature was ramped from 700 degrees C to 950 degrees C. The catalysts were compared based on their fuel conversion, H-2 yield and the selectivity of different short-chain hydrocarbons. The results showed that all three catalysts had both high fuel conversion and H-2 yield in the optimal ATR operation temperatures. The H-2 yield and fuel conversion were increasing in the order Rh/Mn, Rh/La, Rh/Co. To get further insight in the difference between the materials the fresh and aged catalytic materials were characterized. The characterization methods used were H-2-temperature programmed reduction (H-2-TPR), powder X-ray diffraction (XRD), and BET surface measurements. The BET surface measurements showed that promotion with La gave improved thermal stability of the material. The XRD showed a high dispersion of all metals except Co, which was present as crystals in the size range of the particles of the support.
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| 18. |
- Granlund, Moa Z., et al.
(författare)
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Evaluation of Co, La, and Mn promoted Rh catalysts for autothermal reforming of commercial diesel : Aging and characterization
- 2015
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Ingår i: Applied Catalysis B. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 172, s. 145-153
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Tidskriftsartikel (refereegranskat)abstract
- In this study, three bimetallic catalysts are evaluated for autothermal reforming (AIR) of fuels (1 wt.% Rh and 6 wt.% X (X= Co, La or Mn) supported on high-surface area CeO2-ZrO2). The catalysts are aged for approximately 35 h and carefully characterized both as fresh and aged materials. The objective is to illuminate the changes in material properties after time on stream as well as the differences among the materials. The changes in material properties are evaluated by H-2-TPR, BET surface area analysis, TEM, SEM, and STEM. The material's tendency to coke is investigated by TPO analysis. The three materials exhibit promising initial activity. However, the Co-promoted sample decreases sharply in activity after 25 h of operation. Meanwhile, the other two materials display a more stable activity throughout the evaluated time. The deactivation of the Co-promoted material could be linked to the high amount of coke deposited during operation. Based on the results from the activity evaluation and characterization, the material promoted with lanthanum displays the most promising results. The addition of lanthanum resulted in a catalyst that was both stable and had high activity, even though a low rhodium loading is used. The material also shows superior thermal resistance compared to the other two materials. In addition, the tendency to coke is significantly lower compered to the other materials, which is especially beneficial when dealing with AIR of complex fuels.
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| 19. |
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| 20. |
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| 21. |
- Hedelin, M., et al.
(författare)
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Dietary intake of fish, omega-3, omega-6 polyunsaturated fatty acids and vitamin D and the prevalence of psychotic-like symptoms in a cohort of 33 000 women from the general population
- 2010
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Ingår i: BMC Psychiatry. - 1471-244X. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Background: Low intake of fish, polyunsaturated fatty acids (PUFA) and vitamin D deficiency has been suggested to play a role in the development of schizophrenia. Our aim was to evaluate the association between the intake of different fish species, PUFA and vitamin D and the prevalence of psychotic-like symptoms in a population-based study among Swedish women. Methods: Dietary intake was estimated using a food frequency questionnaire among 33 623 women aged 30-49 years at enrolment (1991/92). Information on psychotic- like symptoms was derived from a follow-up questionnaire in the years 2002/03. Participants were classified into three predefined levels: low, middle and high frequency of symptoms. The association between diet and psychotic- like symptoms was summarized in terms of relative risks (RR) and corresponding 95% confidence intervals and was evaluated by energy-adjusted multinomial logistic regression. Results: 18 411 women were classified as having a low level of psychotic- like symptoms, 14 395 as middle and 817 as having a high level. The risk of high level symptoms was 53% (95% CI, 30-69%) lower among women who ate fish 3-4 times per week compared to women who never ate fish. The risk was also lower for women with a high intake of omega-3 and omega-6 PUFA compared to women with a lower intake of these fatty acids. The effect was most pronounced for omega-6 PUFAs. The RR comparing the highest to the lowest quartile of omega-6 PUFAs intake was 0.78 (95% CI, 0.64-0.97). The associations were J-shaped with the strongest reduced risk for an intermediate intake of fish or PUFA. For fatty fish (herring/mackerel, salmon-type fish), the strongest inverse association was found for an intermediate intake (RR: 0.81, 95% CI, 0.66-0.98), whereas a high intake of fatty fish was associated with an increased risk of psychotic- like symptoms (RR: 1.90, 95% CI, 1.34-2.70). Women in the highest compared with the lowest quartile of vitamin D consumption experienced a 37% (95% CI, 22-50%) lower risk of psychotic- like symptoms. Conclusion: Our findings raise a possibility that adult women with a high intake of fish, omega-3 or omega-6 PUFA and vitamin D have a lower rate of psychotic- like symptoms.
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| 22. |
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| 23. |
- Johansson, Maria A, et al.
(författare)
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Early-Life Gut Bacteria Associate with IL-4-, IL-10- and IFN-γ Production at Two Years of Age
- 2012
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:11, s. e49315-(9 pp)
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Tidskriftsartikel (refereegranskat)abstract
- Microbial exposure early in life influences immune maturation and potentially also the development of immune-mediated disease. Here we studied early-life gut colonization in relation to cytokine responses at two years of age. Fecal samples were collected from infants during the first two months of life. DNA was extracted from the fecal samples and Bifidobacterium (B.) adolescentis, B. breve, B. bifidum, a group of lactobacilli (L. casei, L. paracasei and L. rhamnosus) as well as Staphylococcus (S.) aureus were detected with real time PCR. Peripheral mononuclear cells were stimulated with phytohaemagglutinin (PHA) and numbers of IL-4-, IL-10- and IFN-γ secreting cells were evaluated using ELISpot. We further stimulated peripheral blood mononuclear cells with bacterial supernatants in vitro and assessed the IL-4-, IL-10- and IFN-γ inducing capacity by flow cytometry and ELISA. Early S. aureus colonization associated with higher numbers of IL-4- (p = 0.022) and IL-10 (p = 0.016) producing cells at two years of age. In contrast to colonization with S. aureus alone, co-colonization with lactobacilli associated with suppression of IL-4- (p = 0.004), IL-10- (p = 0.004) and IFN-γ (p = 0.034) secreting cells. In vitro stimulations of mononuclear cells with bacterial supernatants supported a suppressive role of L. rhamnosus GG on S. aureus-induced cytokine responses. We demonstrate that the early gut colonization pattern associates with the PHA-induced cytokine profile at two years of age and our in vitro findings support that specific bacterial species influence the T helper cell subsets. This suggests that dysbiosis in the early microbiota may modulate the risk of developing inflammatory conditions like allergy.
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| 24. |
- Karatzas, Xanthias, et al.
(författare)
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Characterization and optimization of an autothermal diesel and jet fuel reformer for 5 kW(e) mobile fuel cell applications
- 2010
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Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947 .- 1873-3212. ; 156:2, s. 366-379
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Tidskriftsartikel (refereegranskat)abstract
- The present paper describes the characterization of an autothermal reformer designed to generate hydrogen by autothermal reforming (ATR) from commercial diesel fuel (similar to 10 ppm S) and jet fuel (similar to 200 ppm S) for a 5 kW(e) polymer electrolyte fuel cell (PEFC). Commercial noble metal-based catalysts supported on 900 cpsi cordierite monoliths substrates were used for ATR with reproducible results. Parameters investigated in this study were the variation of the fuel inlet temperature, fuel flow and the H2O/C and O-2/C ratios. Temperature profiles were studied both in the axial and radial directions of the reformer. Product gas composition was analyzed using gas chromatography. It was concluded from the experiments that an elevated fuel inlet temperature (>= 60 degrees C) and a higher degree of fuel dispersion, generated via a single-fluid pressurized-swirl nozzle at high fuel flow, significantly improved the performance of the reformer. Complete fuel conversion, a reforming efficiency of 81% and an H-2 selectivity of 96% were established for ATR of diesel at P=5kW(e), H2O/C = 2.5, O-2/C = 0.49 and a fuel inlet temperature of 60 degrees C. No hot-spot formation and negligible coke formation were observed in the reactor at these operating conditions. The reforming of jet fuel resulted in a reforming efficiency of only 42%. A plausible cause is the coke deposition, originating from the aromatics present in the fuel, and the adsorption of S-compounds on the active sites of the reforming catalyst. Our results indicate possibilities for the developed catalytic reformer to be used in mobile fuel cell applications for energy-efficient hydrogen production from diesel fuel.
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| 25. |
- L. Bergman, Susanna, et al.
(författare)
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In-situ characterization by Near-Ambient Pressure XPS of the catalytically active phase of Pt/Al2O3 during NO and CO oxidation
- 2018
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Ingår i: Applied Catalysis B. - Amsterdam : Elsevier. - 0926-3373 .- 1873-3883. ; 220, s. 506-511
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Tidskriftsartikel (refereegranskat)abstract
- This study concerns near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) studies of a Pt/Al2O3 diesel oxidation catalyst used in exhaust aftertreatment. We apply the technique to an industrial-grade porous catalyst, thus bridging both the pressure and materials gap, and probe the shift in binding energy of Pt 4d under different atmospheres. We observe that oxidizing atmospheres induce a shift in binding energy, corresponding to changes in Pt oxidation state, especially pronounced under an atmosphere of NO and O2. Such changes in Pt oxidation state have previously been linked to dynamic changes in NO oxidation activity.
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| 27. |
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| 28. |
- Lind, Alexandra, et al.
(författare)
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Ocular findings and growth in 5-year-old preterm children born to mothers with preeclampsia
- 2020
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Ingår i: Acta Ophthalmologica. - : Wiley. - 1755-375X .- 1755-3768. ; 98:7, s. 671-678
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Tidskriftsartikel (refereegranskat)abstract
- Purpose To evaluate growth, blood pressure and ophthalmological status in preschool children born preterm to mothers with preeclampsia. Methods In a prospective cohort study, 78 children (34 girls) born preterm without retinopathy of prematurity were examined regarding length/height, weight, head circumference and insulin-like growth factor I (IGF-I) at birth and at 5 years of age. At 5 years, IGF-binding protein 3 and blood pressure were also measured. A detailed ophthalmological examination including ocular dimensions, fundus morphology, visual fields, visual evoked potentials and perceptual visual dysfunction was performed. Children born to preeclamptic mothers (n = 24) were compared to children with non-preeclamptic mothers (n = 54). Results Children exposed to preeclampsia had lower weight (p = 0.0002, mean difference -1.46, 95% CI -2.09; -0.83), length (p = 0.013, -1.10, 95% CI -1.92; -0.23) and IGF-I levels (p = 0.0002, -26.0, 95% CI -36.0; -16.1) at birth compared to non-exposed children. At 5 years of age, the preeclamptic group had larger optic cup areas (p = 0.0006, 0.32, 95% CI 0.15; 0.46, in right eye, p = 0.049, 0.18, 95% CI 0.001; 0.35, in left eye). There was no significant difference between the groups regarding other ophthalmological findings or blood pressure. Children with reduced eye motility had lower neonatal IGF-I levels (p = 0.033, 15.5, 95% CI 1.1; 30.3). Conclusion Preeclampsia was shown to affect growth and IGF-I levels, confirming previous studies. Children exposed to preeclampsia were shown to have larger optic cup areas. Furthermore, lower neonatal IGF-I levels were seen in preterm children with reduced eye motility at 5 years of age.
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| 29. |
- Lindström, B., et al.
(författare)
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Diesel fuel reformer for automotive fuel cell applications
- 2009
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Ingår i: International journal of hydrogen energy. - : Elsevier BV. - 0360-3199 .- 1879-3487. ; 34:8, s. 3367-3381
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Tidskriftsartikel (refereegranskat)abstract
- Fuel economy and emission abatement are issues, which are highly prioritized areas in the automotive industry of today. The debate about climate change has in recent years even more emphasized the importance of these issues and has increased the search for finding sustainable technical solutions. This paper describes an effort to develop an innovative and environmentally-benign hydrogen generation system operating on commercial diesel fuel to avoid running the engine to supply electricity at stand-still. The use of a fuel cell-based auxiliary power unit (APU) has the potential of delivering electricity at high efficiencies independent of the heavy-duty truck engine. During the reformer development phase, spray formation and mixing of reactants proved to be crucial to obtain high reforming efficiencies and low diesel slip. The diesel is being injected through a nozzle creating a spray of fine droplets of a size which can establish rapid evaporation. Air and steam are being pre-heated and injected into the mixture chamber and subsequently mixed with the evaporated diesel fuel. Depending on the operating parameters, a part of the fuel is being oxidized and produces heat. Autothermal reforming was chosen to circumvent the heat transfer problem in catalytic steam reforming. By supplying heat directly to the catalyst surface by an oxidation reaction the heat demand of the strongly endothermic steam reforming reaction can be fulfilled. We employed CFD calculations, which revealed the importance of avoiding large recirculation zones leading to a prolonged residence time of the hydrocarbon molecules and causing auto-ignition and excessive temperatures in the catalyst. Five different reformer generations are being described and discussed in detail in this publication. The first one was based on a fixed bed reactor, while the other four all relied on catalytic monoliths enabling low pressure drops. The early reactor designs all suffered from auto-ignition and instability problems. The latter generations exhibited a considerably more stable temperature profile in the reformer. The conversion of diesel and the reformer efficiencies are significantly higher than the early generation diesel reformers.
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| 30. |
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| 31. |
- Louka, A S, et al.
(författare)
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HLA in coeliac disease families: a novel test of risk modification by the 'other' haplotype when at least one DQA1*05-DQB1*02 haplotype is carried.
- 2002
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Ingår i: Tissue antigens. - 0001-2815 .- 1399-0039. ; 60:2, s. 147-54
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Tidskriftsartikel (refereegranskat)abstract
- Predisposition to coeliac disease (CD) involves HLA genes. We investigated whether any haplotypes modify risk when carried trans to a known high-risk haplotype, DQA1*05-DQB1*02. Earlier attempts to rank levels of risk contributed by the 'other' haplotype were burdened by use of case-control populations; haplotype frequencies were estimated and homozygosity was only presumed. In contrast, exact haplotypes can be determined and allele transmission can be traced in families. A similar study in narcolepsy reported strata of different degrees of predisposition, attributable to the 'other' haplotype. A gene dosage effect similar to that described for DQB1*02 in CD, has also been reported in narcolepsy. We genotyped 439 simplex/multiplex trios for DQA1 and DQB1. We designed a new statistic to test risk modulation by the trans haplotype, even if the affected offspring was homozygous. We tested for significant deviation in transmission of the 'other' haplotype, i.e., modification of DQA1*05-DQB1*02 risk. We also addressed the proposed difference in risk, between DQA1*05-DQB1*02 homozygotes and DQA1*05-DQB1*02/DQA1*0201-DQB1*02 heterozygotes, reported in Southern Europe. We confirmed a DQB1*02 gene dosage effect. However, no haplotypes were found to modify risk when carried trans to DQA1*05-DQB1*02, except DQA1*05-DQB1*02 and DQA1*0201-DQB1*02 which were already known. We did not find credible evidence for a difference in risk conferred by DQA1*05-DQB1*02 and DQA1*0201-DQB1*02, when carried with DQA1*05-DQB1*02. The new test, which directly inspects haplotype transmissions rather than estimated haplotype frequencies, was used to demonstrate that the 'other' haplotype (except DQA1*05-DQB1*02 and DQA1*0201-DQB1*02) does not modify risk conferred by DQA1*05-DQB1*02. The test is applicable to other diseases.
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| 32. |
- Moen, Inger E, et al.
(författare)
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Dietary intake and nutritional status in a Scandinavian adult cystic fibrosis-population compared with recommendations
- 2011
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Ingår i: Food & Nutrition Research. - : SNF Swedish Nutrition Foundation. - 1654-6628 .- 1654-661X. ; 55, s. 7561-
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Malnutrition is a well-known complication in cystic fibrosis (CF). There is good evidence that maintaining a normal body-weight correlates well with improved survival in CF. Energy intake in excess of 120% of the estimated average requirement (EAR) has been advised since 1980s. OBJECTIVES: To investigate the nutritional intake and status in the adult Scandinavian CF-population. SUBJECTS/METHODS: A cross-sectional multi-centre study was used to investigate the nutritional status of 456 adult CF-patients (2003 2006). Height and weight were measured and body mass index (BMI) and z-scores were calculated. Pulmonary function was examined by dynamic spirometry. A 7-day pre-coded food record (FR) obtained energy and nutrient intake data in 180 patients. RESULTS: The mean energy intake was 114 (SD 30.0)% of EAR and thus significantly lower than the target of 120% EAR (p< 0.001) for patients with pancreatic insufficiency (PI) (n=136). Mean BMI was 22.0 (SD 2.9), the prevalence of BMI <18 was 13% and the prevalence of BMI ≥25 was 15% (n=136). Mean BMI was 20.8 (SD 2.4) in PI-patients with FEV(1) <70% and 23.2% (SD 3.0), in PI-patients with FEV(1) ≥70%, mean difference 2.4, (95% CI: 1.5, 3.3) (p<0.001), but there was no difference in energy intake. BMI ≥18.5 and a reported energy intake <120% were revealed in 54% of the PI-patients. CONCLUSIONS: The energy intake did not reach the recommended 120% EAR, but the prevalence of underweight was lower than reported in other studies. The recommendation may exceed the requirement for a number of CF-patients. The nutritional status must still be closely monitored and nutritional advice and intervention should be individualised and adjusted to actual needs.
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| 33. |
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| 34. |
- Nilsson, Anna C., et al.
(författare)
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A pilot phase 2a, randomized, double-blind, placebo-controlled study to explore the antiviral activity, clinical outcomes, safety, and tolerability of rilematovir at two dose levels in non-hospitalized adults with respiratory syncytial virus infection
- 2023
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Ingår i: Clinical Microbiology and Infection. - 1198-743X. ; 29:10, s. 1320-1327
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To assess the antiviral effect, clinical outcomes, and safety of the respiratory syncytial virus (RSV) fusion inhibitor rilematovir in non-hospitalized RSV-infected adults. Methods: This phase 2a, double-blind, multicentre study randomly assigned RSV-positive adult outpatients ≤5 days from symptom onset 1:1:1 to receive rilematovir 500 mg, 80 mg, or placebo once-daily for 7 days. Antiviral effect was assessed by RSV RNA viral load (VL), measured by quantitative RT-PCR, and Kaplan-Meier (KM) estimates of time to undetectable VL. Clinical course was assessed by KM estimates of median time to resolution of key RSV symptoms assessed through patient-reported outcomes. Results: RSV-positive patients (n = 72) were randomly assigned; 66 had confirmed RSV infection and received rilematovir 500 mg (n = 23), 80 mg (n = 21) or placebo (n = 22). Differences versus placebo in mean RSV RNA VL area under the curve (90% CI) through days 3, 5 and 8, respectively, were 0.09 (−0.837; 1.011), −0.10 (−2.171; 1.963), and −1.03 (−4.746; 2.682) log10 copies.day/mL for rilematovir 500 mg, and 1.25 (0.291; 2.204), 2.53 (0.430; 4.634), and 3.85 (0.097; 7.599) log10 copies.day/mL for rilematovir 80 mg. KM estimates of median (90% CI) time-to-first confirmed undetectable VL were 5.9 (3.85; 6.90), 8.0 (6.86; 12.80) and 7.0 (6.62; 10.88) days and 5.7 (2.93; 7.01), 8.1 (6.74; 12.80) and 7.9 (6.62; 11.74) days in patients with symptom onset ≤3 days, for rilematovir 500 mg, 80 mg, and placebo, respectively. KM estimates of median (90% CI) time to resolution of key RSV symptoms were 7.1 (5.03; 11.43), 7.6 (5.93; 8.32), and 9.6 (5.95; 14.00) days for rilematovir 500 mg, 80 mg, and placebo, respectively; and in patients with symptom onset ≤3 days, median 8.0, 7.6, and 11.8 days, respectively. Discussion: Rilematovir use, initiated early, suggests a potential clinical benefit in RSV-infected adults, with data supporting development of RSV therapeutic options. Trial registration: This study is registered with clinicaltrials.gov (NCT03379675).
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| 35. |
- Nilsson, C, et al.
(författare)
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Epstein-Barr virus and cytomegalovirus are differentially associated with numbers of cytokine-producing cells and early atopy
- 2009
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Ingår i: Clinical and Experimental Allergy. - Oxford : Blackwell. - 0954-7894 .- 1365-2222. ; 39:4, s. 509-517
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: We have previously shown that Epstein-Barr virus (EBV) seropositivity, at 2 years of age, was inversely related to IgE-sensitization and that this effect was enhanced when EBV is combined with cytomegalovirus (CMV) seropositivity. We hypothesize that early exposure to EBV or CMV will affect the cytokine balance in the individual.OBJECTIVE: The aim of this study was to relate the cytokine profile in peripheral blood mononuclear cells (PBMC) to the EBV and CMV serostatus and IgE-sensitization in children at 2 years of age.METHODS: Seventy-five children were followed prospectively from birth until 2 years of age. Their EBV and CMV serostatus was correlated to the numbers of IFN-gamma, IL-4, IL-10 and IL-12-producing PBMC following PHA stimulation in vitro. Skin prick tests and allergen-specific IgE antibodies were used to assess IgE-sensitization.RESULTS: In the study cohort, there was an inverse association between EBV seropositivity and IgE-sensitization but not with CMV seropositivity. Following linear regression analysis, we did not detect any statistically significant associations between children with IgG antibodies against EBV at 2 years of age and the investigated cytokines. However, there was a non-significant tendency to a positive association between high numbers of all individual cytokine-producing cells and EBV seropositivity. Children who were CMV seropositive had significantly higher numbers of IFN-gamma and lower numbers of IL-4-producing cells compared with CMV negative children. There was a significant, positive association between the number of IL-4-producing cells and IgE-sensitization.CONCLUSION: Taken together our results indicate that infections with EBV and CMV in different ways will interact with the immune system and may protect children from developing early atopy.
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| 36. |
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| 37. |
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| 38. |
- Nilsson, Josefin, 1973, et al.
(författare)
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Normal visual evoked potentials in preschool children born small for gestational age.
- 2011
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Ingår i: Acta paediatrica (Oslo, Norway : 1992). - : Wiley. - 1651-2227 .- 0803-5253. ; 100:8, s. 1092-6
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies have shown visual evoked potential (VEP) abnormalities in infants and animals born small for gestational age (SGA) compared with controls. The current exploratory study aims to investigate whether VEP abnormalities persist in older ages.
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| 39. |
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| 40. |
- Nilsson, Marita, et al.
(författare)
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Assessing the adaptability to varying fuel supply of an autothermal reformer
- 2008
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Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947 .- 1873-3212. ; 142, s. 309-317
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Tidskriftsartikel (refereegranskat)abstract
- The present paper describes the study of an autothermal reformer and its fuel-flexible capabilities. Experiments have been performed in a reactor designed to generate hydrogen by autothermal reforming for a 1-5 kW(e) polymer electrolyte fuel cell. Both logistic fuels (diesel, gasoline, and E85) and alternative fuel candidates (methanol, ethanol, and dimethyl ether) were tested in the reformer. The same catalyst composition, Rh supported on Ce/La-doped gamma-Al2O3 and deposited on cordierite monoliths, was used for all fuels. The practical feasibility of reforming each fuel in the present reactor design was tested and evaluated in terms of fuel conversion and selectivity to hydrogen and carbon dioxide. Temperature profiles were studied both in the axial and radial direction of the reformer. It was concluded from the experiments that the reformer design was most suitable for use with hydrocarbon mixtures Such as diesel, gasoline, and E85, where it represents a good basis for an optimized multifuel-reformer design.
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| 41. |
- Nilsson, Marita, et al.
(författare)
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Catalytic properties of Pd supported on ZnO/ZnAl2O4/Al2O3 mixtures in dimethyl ether autothermal reforming
- 2009
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Ingår i: Applied Catalysis B. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 86:02-jan, s. 18-26
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Tidskriftsartikel (refereegranskat)abstract
- The catalytic properties of Pd supported on mixtures of zinc oxide, zinc aluminate, and alumina, prepared from gamma-alumina and zinc nitrate, were studied for autothermal reforming (ATR) of dimethyl ether (DME). The performance of the catalysts was tested in a small-scale reactor, using cordierite monoliths as substrate. The catalysts exhibited high activity and generated hydrogen-rich product gases with CO concentrations below 5 vol.% in the temperature range between 350 and 450 degrees C (at O-2:DME = 0.7, H2O:DME = 2.5, and GHSV = 15000 h(-1)). The highest DME conversion was obtained for a catalyst in which the support comprised mainly ZnAl2O4. Physical mixing of the catalysts with gamma-Al2O3 resulted in increased DME conversion but a lowering of the CO2 selectivity. The catalysts were characterized by CO chemisorption, liquid nitrogen adsorption, temperature-programmed desorption of ammonia, temperature-programmed reduction, transmission electron microscopy, and X-ray diffraction. It was found that decreasing surface area and decreasing number of acid sites, caused by thermal treatment during generation of the supports, did not affect the activity negatively. The high CO2 selectivity of the catalysts was correlated with PdZn alloy formation.
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| 42. |
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| 43. |
- Nilsson, Marita, et al.
(författare)
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Evaluation of Pd-based catalysts and the influence of operating conditions for autothermal reforming of dimethyl ether
- 2007
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Ingår i: Applied Catalysis B. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 76, s. 41-49
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Tidskriftsartikel (refereegranskat)abstract
- A series of different Pd-based catalysts supported on ceramic monoliths were synthesized and tested in a screening study for autothermal reforming of dimethyl ether (DME). Alumina-supported Pd was shown to be very active for this reaction at temperatures between 350 and 400 degrees C. Adding Zn to Pd/gamma-Al2O3 decreased the activity of decomposition reactions leading to better reforming activity, and resulting in high selectivity to carbon dioxide. Pd-Zn/gamma-Al2O3 was further evaluated in a parameter study varying oxygen-to-DME ratio, steam-to-DME ratio and temperature. The effect on the reformer performance of changing the operating conditions is discussed. The Pd-Zn/gamma-Al2O3 catalyst generated carbon monoxide concentrations below 5%, and hydrogen concentrations close to 50%. The catalyst performance was significantly improved by preconditioning in hydrogen. Results from a first round of catalyst characterization studies suggest that Pd-Zn species are formed on the alumina support following reduction
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| 44. |
- Nilsson, Marita
(författare)
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Hydrogen Generation for Fuel Cells in Auxiliary Power Systems
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Heavy-duty trucks are in idle operation during long periods of time, providing the vehicles with electricity via the alternator at standstill. Idling trucks contribute to large amounts of emissions and high fuel consumption as a result of the low efficiency from fuel to electricity. Auxiliary power units, which operate independently of the main engine, are promising alternatives for supplying trucks with electricity. Fuel cell-based auxiliary power units could offer high efficiencies and low noise. The hydrogen required for the fuel cell could be generated in an onboard fuel reformer using the existing truck fuel. The work presented in this thesis concerns hydrogen generation from transportation fuels by autothermal reforming focusing on the application of fuel cell auxiliary power units. Diesel and dimethyl ether have been the fuels of main focus. The work includes reactor design aspects, preparation and testing of reforming catalysts including characterization studies and evaluation of operating conditions. The thesis is a summary of five scientific papers. Major issues for succeeding with diesel reforming are fuel injection, reactant mixing and achieving fuel cell quality reformate. The results obtained in this work contribute to the continued research and development of diesel reforming catalysts and processes. A diesel reformer, designed to generate hydrogen to feed a 5 kWe polymer electrolyte fuel cell has been evaluated for autothermal reforming of commercial diesel fuel. The operational results show the feasibility of the design to generate hydrogen-rich gases from complex diesel fuel mixtures and have, together with CFD calculations, been supportive in the development of a new improved reformer design. In addition to diesel, the reforming reactor design was shown to run satisfactorily with other hydrocarbon mixtures, such as gasoline and E85. Rh-based catalysts were used in the studies and exhibit high performance during diesel reforming without coke formation on the catalyst surface. An interesting finding is that the addition of Mn to Rh catalysts appears to improve activity during diesel reforming. Therefore, Mn could be considered to be used to decrease the noble metal loading, and thereby the cost, of diesel reforming catalysts. Dimethyl ether is a potential diesel fuel alternative and has lately been considered as hydrogen carrier for fuel cells in truck auxiliary power units. The studies related to dimethyl ether have been focused on the evaluation of Pd-based catalysts and the influence of operating parameters for autothermal reforming. PdZn-based catalysts were found to be very promising for DME reforming, generating product gases with high selectivity to hydrogen and carbon dioxide. The high product selectivity is correlated to PdZn interactions, leading to decreased activity of decomposition reactions. Auxiliary power systems fueled with DME could, therefore, make possible fuel processors with very low complexity compared to diesel-fueled systems. The work presented in this thesis has enhanced our understanding of diesel and DME reforming and will serve as basis for future studies.
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| 45. |
- Nilsson, Marita
(författare)
-
Hydrogen generation from dimethyl ether by autothermal reforming
- 2007
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Heavy-duty trucks are in idle operation during long periods of time, providing the vehicles with electricity via the alternator at standstill. Idling trucks contribute to large amounts of emissions and high fuel consumption as a result of the low efficiency from fuel to electricity. Truck manufacturers are working to develop equipment using auxiliary power units to supply the trucks with electricity, which operate independently of the main engine. Fuel cell-based auxiliary power units could offer high efficiencies and low noise and vibrations. The hydrogen required for the fuel cell can be generated in an onboard fuel reformer. This thesis is devoted to hydrogen generation from dimethyl ether, DME, by autothermal reforming focusing on the application of fuel cell auxiliary power units. In the search for alternative fuels, DME has lately been identified as a promising diesel substitute. The first part of the thesis gives an introduction to the field of DME reforming with a literature survey of recent studies within the area. Included are also results from thermodynamic equilibrium calculations. In the following parts of the thesis, experimental studies on autothermal reforming of DME are presented. A reformer constructed to generate hydrogen to feed a 5 kWe polymer electrolyte fuel cell is evaluated with emphasis on trying to work close to a practically viable process, i.e. without external heating and using gas mixtures resembling real conditions. Additional experiments have been conducted to investigate the use of catalytic oxidation of dimethyl ether as a heat source during startup. The results of these studies are presented in Paper I. In the second experimental study of this thesis, which is presented in Paper II, Pd-based monolithic catalysts are evaluated at small scale for use in autothermal reforming of DME. A screening of various catalyst materials has been performed followed by a study of the influence on the product composition of varying operating parameters such as oxygen-to-DME ratio, steam-to-DME ratio, and temperature.
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| 46. |
- Nilsson, Marita, et al.
(författare)
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Hydrogen generation from dimethyl ether for fuel cell auxiliary power units
- 2006
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 20:5, s. 2164-2169
-
Tidskriftsartikel (refereegranskat)abstract
- Copper-based catalysts have been evaluated for the combined partial oxidation and steam reforming of dimethyl ether (DME) in a reformer designed to produce hydrogen for a full-scale heavy-duty truck auxiliary power unit. The experiments were conducted using gas mixtures similar to realistic operating conditions. A Pd-promoted CuZn catalyst was found to be highly selective for hydrogen production from DME at O-2/DME = 0.25 and H2O/ DME = 2.5. The catalysts were characterized using Brunauer-Emmett-Teller surface area measurement, X-ray diffraction, and temperature-programmed reduction. The copper surface area was determined by pulse chemisorption of nitrous oxide. In addition to the reforming catalyst evaluation, a startup sequence was tested, where DME was catalytically ignited and combusted over platinum or iron oxide catalysts.
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| 47. |
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| 48. |
- Oldin, Anna, et al.
(författare)
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Traumatic dental injuries among children aged 0–17 years in the BITA study – A longitudinal Swedish multicenter study
- 2015
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Ingår i: Dental Traumatology. - : Wiley. - 1600-4469 .- 1600-9657. ; 31:1, s. 9-17
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Tidskriftsartikel (refereegranskat)abstract
- Abstract BACKGROUND/AIM: To prevent traumatic dental injuries (TDI), there is a need for vital information. This information could be reached using certain specific variables. The aim of this study, therefore, was to investigate TDI in different age groups, their etiology, and differences by gender, in Swedish children aged 0-17 years. SUBJECTS AND METHODS: The study included 2363 children in four different age cohorts from 12 Public Dental Service clinics in Sweden. The design was a 5-year longitudinal study including yearly clinical examinations, retrospective and prospective data compiled from dental records and interviews regarding TDI. RESULTS: The prevalence for TDI was 37.6% (889) with no gender differences. Boys suffered more injuries during the spring and fall compared to girls. The incidence of 2.8% varied between the age groups where preschool children presented the highest incidence. No changes in prevalence for TDI were found for the years included in the study. The most common reason for TDI was Falling (42.1%). The frequencies for the etiological factors varied between the ages. CONCLUSIONS: The TDI prevalence showed to be stable at a high level in spite of great efforts in Sweden and worldwide to reduce it. Knowledge in why, where, and when TDI appears is therefore essential for dental personnel who will work to reduce TDI.
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| 49. |
- Olsson, Torsten, 1937, et al.
(författare)
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Cell Swelling, Seizures and Spreading Deprssion: An Impedance Study
- 2006
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Ingår i: Neuroscience. - : Elsevier BV. - 0306-4522. ; 140:2
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Tidskriftsartikel (refereegranskat)abstract
- The cellular processes that take place during the transition from pre-seizure state to seizure remain to be defined. In this study in awake, paralyzed rats, we used an electrical impedance measure of changes in extra-cellular intracranial volume to estimate changes in cell size in acute models of epilepsy. Animals were prepared with extradural electroencephalographic (EEG)/impedance electrodes and a venous catheter. On a subsequent day, animals were paralyzed, ventilated and treated with picrotoxin, kainic acid or fluorocitrate in doses that usually induce epileptiform discharges. We now report that increases in baseline impedance were induced by kainic acid and smaller increases by picrotoxin. We also demonstrated that epileptiform discharges were preceded by small, accelerated increases in impedance. Increases in baseline impedance were highly correlated with increases in power of non-ictal high frequency EEG activity. Seizures were accompanied by increases in impedance and all treatments induced transient, relatively large, increases in impedance often associated with unilateral reductions in low frequency EEG, likely periods of spreading depression. We conclude: cerebral cells swell in convulsant models of epilepsy, that there are pre-ictal accelerations in cell swelling, and that spreading depression-like events are frequently associated with seizures.
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| 50. |
- Raffa, Lina H., et al.
(författare)
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Electrophysiological changes in 12-year-old children born MLP : reduced VEP amplitude in MLP children
- 2017
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Ingår i: British Journal of Ophthalmology. - : BMJ Publishing Group Ltd. - 0007-1161 .- 1468-2079. ; 101:9, s. 1156-1161
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Tidskriftsartikel (refereegranskat)abstract
- AIM: To study the electrophysiological changes in relation to fundus morphology in moderate-to-late preterm (MLP) children with no previous history of retinopathy of prematurity.METHODS: Visual acuity (VA), refraction and fundus variables measured by optical coherence tomography, pattern reversal visual evoked potentials and full-field electroretinography (ff-ERG) were obtained from 22 twelve-year-old MLP children (11 male, 11 female) and 21 full-term controls.RESULTS: There were no significant differences between the MLP and control groups in VA, refraction or optic disc parameters. There was a trend for thinner papillary retinal nerve fibre layer in the MLP group. Visual evoked potential amplitudes (P100) were lower in the MLP group than in controls, that is, right eye p=0.0027, left eye p=0.0037. No differences in latencies were found. After Bonferroni adjustment for multiple testing, no ff-ERG differences were noted between MLP and controls. Lower gestational age was correlated with smaller light-adapted 3.0 b-wave amplitudes (p=0.0076, r=0.565).CONCLUSIONS: Our results indicate that moderate premature birth may affect visual evoked potential amplitudes without clear retinal structural changes in MLP children at 12 years of age.
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