| 1. |
- Agrell, J., et al.
(författare)
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Production of hydrogen by partial oxidation of methanol over Cu/ZnO catalysts prepared by microemulsion technique
- 2001
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Ingår i: Applied Catalysis A. - 0926-860X .- 1873-3875. ; 211:2, s. 239-250
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Tidskriftsartikel (refereegranskat)abstract
- Production of hydrogen by partial oxidation of methanol, using air as oxidant. has been studied over a series of Cu/ZnO catalysts prepared by microemulsion technique. The catalytic activity was compared to that of a reference catalyst prepared by conventional co-precipitation. The BET surface areas of the microemulsion catalysts (30-70 wt.% Cu) ranged from 22 to 36 m(2)/g and were considerably lower than that of the reference (60 m(2)/g). Nevertheless, the microemulsion catalysts were more active in the partial oxidation reaction and exhibited high hydrogen and carbon dioxide selectivities. At a molar O-2/CH3OH ratio of 0.1, hydrogen production was initiated at about 185 degreesC over the microemulsion catalysts. Over the reference, hydrogen production began at 215 degreesC under the same conditions. The catalytic activity was Found to be strongly dependent on the partial pressure of oxygen, which also plays an important role in determining the product distribution. By increasing the O-2/CH3OH ratio, the methanol conversion and carbon dioxide selectivity increase. while production of water occurs at the expense of hydrogen. By TEM and TPR, it was observed that Cu is less well-dispersed in the microemulsion catalysts than in the reference. The higher catalytic activity is not expected considering the lower number of exposed Cu sites, i.e, the turnover frequencies are substantially higher over the microemulsion catalysts. It is possible that, a strong interaction between a small part of CuO and the ZnO lattice is responsible for the higher turnover frequencies of the microemulsion catalysts, or that particular crystallographic Cu planes or surface imperfections are the active sites of the reaction.
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| 5. |
- Jansson, E., Grönvik, K.-O., Johannisson, A., Näslund, K. Westergren, E. and Pilström, L
(författare)
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Monoclonal antibodies to lymphocytes of rainbow trout (Oncorhynchus mykiss)
- 2003
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Ingår i: Fish & Shellfish Immunology. ; 14, s. 239-257
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Tidskriftsartikel (refereegranskat)
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| 6. |
- Li, X P, et al.
(författare)
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A pigment-binding protein essential for regulation of photosynthetic light harvesting
- 2000
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Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 403:6768, s. 391-395
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Tidskriftsartikel (refereegranskat)abstract
- Photosynthetic light harvesting in plants is regulated in response to changes in incident light intensity. Absorption of light that exceeds a plant's capacity for fixation of CO2 results in thermal dissipation of excitation energy in the pigment antenna of photosystem II by a poorly understood mechanism. This regulatory process, termed nonphotochemical quenching, maintains the balance between dissipation and utilization of light energy to minimize generation of oxidizing molecules, thereby protecting the plant against photo-oxidative damage. To identify specific proteins that are involved in nonphotochemical quenching, we have isolated mutants of Arabidopsis thaliana that cannot dissipate excess absorbed light energy. Here we show that the gene encoding PsbS, an intrinsic chlorophyll-binding protein of photosystem II, is necessary for nonphotochemical quenching but not for efficient light harvesting and photosynthesis, These results indicate that PsbS may be the site for nonphotochemical quenching, a finding that has implications for the functional evolution of pigment-binding proteins.
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| 7. |
- Persson, K., et al.
(författare)
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Preparation of alumina-supported palladium catalysts for complete oxidation of methane
- 2003
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Ingår i: Applied Catalysis A. - : Elsevier BV. - 0926-860X .- 1873-3875. ; 249:1, s. 165-174
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Tidskriftsartikel (refereegranskat)abstract
- Alumina-supported palladium catalysts (Pd/Al2O3) have been prepared by incipient wetness (IW), grafting (G) and microemulsion techniques (ME). Two slightly different microemulsion methods have been used (ME1) and (ME2). The catalysts have been calcined at 1000 degreesC for 4 h. The catalysts have then been examined with respect to their activity for the combustion of methane, during heating and cooling ramps. Pd/Al2O3-IW and Pd/Al2O3-ME2 exhibit the highest activity whereas Pd/Al2O3-ME1 and Pd/Al2O3-G are the less active. There is not much of a difference in activity between Pd/Al2O3-IW and Pd/Al2O3-ME2, despite strong differences in palladium particle size observed by TEM analysis. TPO experiments show that Pd/Al2O3-IW and Pd/Al2O3-ME2 present a higher PdO/Pd ratio than the other samples exhibit. The preparation technique affects the reoxidation ability of palladium during cooling, hence the combustion activity of the fresh catalyst, as PdO is more active than Pd for the complete oxidation of methane under lean conditions.
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| 8. |
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| 9. |
- Welch, AA, et al.
(författare)
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Variability of fish consumption within the 10 European countries participating in the European Investigation into Cancer and Nutrition (EPIC) study
- 2002
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Ingår i: Public Health Nutrition. - 1475-2727. ; 5:6B, s. 1273-1285
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To describe-and compare the consumption of total fish (marine foods) and the fish sub-groups - white fish, fatty fish, very fatty fish, fish products and crustacea, in participants from the European Investigation into. Cancer and Nutrition (EPIC) study. Design: Cross-sectional analysis of dietary intake using a computerised standardised 24-hour recall interview. Crude means, means and standard errors adjusted by age, season and day of the week were calculated, stratified by centre and gender, Setting: Twenty-seven redefined centres in the 10 European countries participating in the EPIC study. Subjects.. In total, 35 955 subjects (13 031 men and 22 924 women), aged 35-74 years, selected from the main EPIC cohort. Results: A six- to sevenfold variation in total fish consumption exists in women and men, between the lowest consumption in Germany and the highest in Spain. Overall, white fish represented 49% and 45% of the intake of total fish in women and men, respectively, with the greatest consumption in centres in Spain and Greece and the least in the German and Dutch centres. Consumption of fatty fish reflected that of total fish. However, the greatest intake of very fatty fish was in the coastal areas of northern Europe (Denmark, Sweden and Norway) and in Germany. Consumption of fish products was greater in northern than in southern Europe, with white fish products predominating in centres in France, Italy, Spain, The Netherlands and Norway. Intake of roe and roe products was low. The highest consumption of crustacea was found in the French, Spanish and Italian centres. The number of fish types consumed was greater in southern than in northern Europe. The greatest variability in consumption by day of the week-was found in the countries with - the lowest fish intake. Conclusions: Throughout Europe, substantial geographic variation exists in total fish intake, fish sub-groups and the number of types consumed. Day-to-day variability in consumption is also high.
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