Sökning: "Nitrogen selectivity"

Visar resultat 1 - 5 av 45 avhandlingar innehållade orden Nitrogen selectivity.

  1. 1. Optimization of Pretreatment of Kraft Pulp with Nitrogen Oxides

    Författare :Urban Öjteg; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Kappa number; lignins; Nitric acid; Magnesium; spent liquors; viscosity; softwood; oxygen bleaching; Nitrogen dioxide; Manganese; Oxygen; Nitrogen oxides; pretreatment; Kraft pulp;

    Sammanfattning : Modified kraft pulp subjected to oxygen bleaching following pretreatment with 2% nitrogen dioxide for 140 min with the addition of oxygen resulted in low selectivity after subsequent oxygen bleaching. In contrast, pretreatment in the absence of oxygen removed more than 80% of the lignin after oxygen bleaching and still maintained high selectivity (kappa number less than 5 at viscosity 950 dm3/kg). LÄS MER

  3. 2. PII proteins as global regulators of bacterial nitrogen metabolism

    Författare :Pedro Filipe Teixeira; Stefan Nordlund; Ray Dixon; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Rhodospirillum rubrum; nitrogen metabolism; signal transduction; PII proteins; Biochemistry; Biokemi; Biochemistry; biokemi;

    Sammanfattning : Nitrogen is an essential element to sustain life, being a component of most biological macromolecules. In spite of the abundance of gaseous N2, the availability of nitrogen compounds that can be readily used by most microorganisms is scarce and its production energetically demanding. LÄS MER

  4. 3. Microfabricated Gas Sensors Based on Hydrothermally Grown 1-D ZnO Nanostructures

    Författare :Mingzhi Jiao; Hugo Nguyen; Klas Hjort; Anita Lloyd Spetz; Uppsala universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; gas sensor; zinc oxide; on-chip; hydrothermal growth; nanorods; nanowires; annealing; palladium oxide; photoluminescence; alloy; sensitivity; selectivity; stability;

    Sammanfattning : In this thesis, gas sensors based on on-chip hydrothermally grown 1-D zinc oxide (ZnO) nanostructures are presented, to improve the sensitivity, selectivity, and stability of the gas sensors.Metal-oxide-semiconductor (MOS) gas sensors are well-established tools for the monitoring of air quality indoors and outdoors. LÄS MER

  5. 4. Novel catalysts development for NOx reduction from H2 combustion engines

    Författare :Jieling Shao; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; H2-SCR; SSZ-13 zeolite; in-situ DRIFTS; Iridium; Nitrogen selectivity; Platinum; reduction pretreatment; temperature intervals; BETA zeolite; Palladium;

    Sammanfattning : Hydrogen, as a clean energy carrier, burns without producing any carbon emissions. Hydrogen internal combustion engines (H2-ICE) are considered an alternative for the transition from conventional fossil-fuel vehicles. LÄS MER

  7. 5. Hemiparasites in the Subarctic: Resource acquisition, growth and population dynamics

    Författare :Carin H Nilsson; Biologiska institutionen; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; population dynamics; selectivity; Phenotypic plasticity; fitness; Plant ecology; Växtekologi;

    Sammanfattning : Parasitic plants are found in nearly every major terrestrial ecosystem and can be divided into two groups, holoparasites (lacking chlorophyll) and hemiparasites (chlorophyllous). The host-parasite connection is either situated above (stem parasites) or below ground (root parasites). LÄS MER