Sökning: "nitrogen depletion"

Visar resultat 1 - 5 av 36 avhandlingar innehållade orden nitrogen depletion.

1. 1. Nitrogen Losses from a Clay-rich Soil used for Cereal Production in south-western Sweden

   Författare :Magdalena Wallmann; Göteborgs universitet; []
   Nyckelord :LANTBRUKSVETENSKAPER; AGRICULTURAL SCIENCES; LANTBRUKSVETENSKAPER; AGRICULTURAL SCIENCES; nitrogen; fertilisers; soil; nitrous oxide; nitrogen leaching; 15N; nitrogen use efficiency; nitrogen budget; agriculture; Sweden;

   Sammanfattning : Addition of fertiliser nitrogen (N) in crop production increases yields and protein contents, but all is not taken up by the crop. Instead, some of the N is lost to air and waters, contributing e.g. to climate change, stratospheric ozone depletion, eutrophication and acidification. LÄS MER

3. 2. Microstructure and properties of welds in the lean duplex stainless steel LDX 2101

   Författare :Elin M. Westin; John Ågren; Hannu Hänninen; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Duplex stainless steel; welding; HAZ; nitrogen; manganese; microstructure; austenite formation; phase balance; precipitates; element distribution; segregation; depletion; solidification; pitting corrosion resistance; solidification; element loss; evaporation; deposition; weld oxide; thermo-mechanical simulation; thermodynamic modelling; EPMA; XPS; post-weld cleaning; pickling; Metallurgical process and manufacturing engineering; Metallurgisk process- och produktionsteknik;

   Sammanfattning : Duplex stainless steels can be very attractive alternatives to austenitic grades due to their almost double strength at equal pitting corrosion resistance. When welding, the duplex alloys normally require addition of filler metal, while the commodity austenitic grades can often be welded autogenously. LÄS MER

4. 3. Metabolic engineering and cultivation strategies for recombinant production of (R)-3-hydroxybutyrate

   Författare :Mariel Perez-Zabaleta; Gen Larsson; Antonius J. A. van Maris; Diethard Mattanovich; KTH; []
   Nyckelord :Escherichia coli; R -3-hydroxybutyrate; nitrogen limitation; nitrogen depletion; lignocellulose; fed batch; acetate; β-ketothiolase; acetoacetyl-CoA reductase; Halomonas boliviensis.; Bioteknologi; Biotechnology;

   Sammanfattning : Metabolic engineering and process engineering are two powerful disciplines to design and improve microbial processes for sustainable production of an extensive number of compounds ranging from chemicals to pharmaceuticals. The aim of this thesis was to synergistically combine these two disciplines to improve the production of a model chemical called (R)-3-hydroxybutyrate (3HB), which is a medium-value product with a stereocenter and two functional groups. LÄS MER

5. 4. Benthic metabolism and sediment nitrogen cycling in Baltic sea coastal areas : the role of eutrophication, hypoxia and bioturbation

   Författare :Stefano Bonaglia; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Eutrophication; Sediment; Benthic Flux; Nitrogen Cycle; Denitrification; Baltic Sea; Biogeochemistry; biogeokemi; marin- och brackvattensekologi; Marine and Brackish Water Ecology; Marine Ecology; marin ekologi; geokemi; Geochemistry;

   Sammanfattning : Eutrophication is one of the greatest threats for the Baltic Sea, and one of its more critical consequences is bottom water hypoxia. Nutrient enrichment and oxygen-depletion affect both the deep central basins and a number of coastal areas, even though strategies for nutrient reduction have lately been implemented. LÄS MER

7. 5. Optimizing processes for biological nitrogen removal in Nakivubo wetland, Uganda

   Författare :Joseph Kyambadde; Gunnel Dalhammar; Karin Tonderski-Sundblad; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Environmental technology; Ammonium-oxidizing bacteria; Biological nitrogen removal; Coliform retention; Constructed wetlands; Cyperus papyrus; Miljöteknik; Environmental engineering; Miljöteknik;

   Sammanfattning : The ability of Nakivubo wetland (which has performed tertiary water treatment for Kampala city for the past 40 years) to respond to pollution and to protect the water quality of Inner Murchison Bay of Lake Victoria was investigated. The aim of this study was to assess the capacity of Nakivubo wetland to remove nitrogen from the wastewater after its recent encroachment and modification, in order to optimize biological nitrogen removal processes using constructed wetland technology. LÄS MER