Sökning: "oxygen evolution"

Visar resultat 1 - 5 av 133 avhandlingar innehållade orden oxygen evolution.

  1. 1. Critical potential and oxygen evolution of the chlorate anode

    Författare :Linda Nylén; Göran Lindbergh; Yohannes Kiros; KTH; []
    Nyckelord :ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; chlorate; chloride oxidation; oxygen evolution; critical anode potential; chromate; DSA; mass transport; RDE; Chemical engineering; Kemiteknik;

    Sammanfattning : In the chlorate process, natural convection arises thanks to the hydrogen evolving cathode. This increases the mass transport of the different species in the chlorate electrolyte. There is a strong connection between mass transport and the kinetics of the electrode reactions. LÄS MER

  2. 2. The evolution of ribonucleotide reductases

    Författare :Daniel Lundin; Anthony Poole; Britt-Marie Sjöberg; Christos Ouzounis; Stockholms universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; Evolution; ribonucleotide reductase; horizontal gene transfer; phylogeny; protein classification; Molecular biology; Molekylärbiologi; Molecular Biology; molekylärbiologi;

    Sammanfattning : Ribonucleotide reductase (RNR) catalyses the transformation of RNA building blocks, ribonucleotides, to DNA building blocks, deoxyribonucleotides. This is the only extant reaction pathway for de novo synthesis of DNA building blocks and the enzyme is thus necessary for life. RNR is found in all but a few organisms. LÄS MER

  3. 3. Ocean chemistry and the evolution of multicellularity

    Författare :Emma U. Hammarlund; Stefan Bengtson; Donald Canfield; Nils Holm; Graham Budd; Stockholms universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; Geochemistry; biology; paleontology; evolution; multicellularity; geokemi; Geochemistry;

    Sammanfattning : Oxygen has been assumed to be a vital trigger for the evolution of multicellular life forms on Earth, partly based on its power to promote substantial energy flux in cell respiration and partly as biosynthesis of compounds like collagen require oxygen. However, the co-evolution of large life and the Earth’s chemical environment is not well understood at present, and there is particular disagreement in the field about whether the Cambrian explosion of animal life forms was a chemical or biological event. LÄS MER

  4. 4. Egg size evolution and paternal care in pipefishes

    Författare :Inês Braga Gonçalves; Göteborgs universitet; Göteborgs universitet; Gothenburg University; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Egg size; embryo development; embryo survival; hypoxia; male quality; mate choice; mating constraints; oxygen; parental care; parental effects; paternal care; reproductive compensation; sex-role reversal; sexual conflict; Syngnathidae; Syngnathus typhle;

    Sammanfattning : In this thesis I explore how sexual selection, sexual conflicts, coevolution with parental care and an environmental selective agent (hypoxia) affect the evolution of different egg characteristics and embryo survival and size in pipefishes (Syngnathidae). In the broad-nosed pipefish, Syngnathus typhle Linnaeus, both sexes prefer to mate with large partners; large females produce more and larger eggs and large males can care for more young, and, as shown in this thesis, invest more per embryo and provide better oxygenation during brooding. LÄS MER

  5. 5. Factors Related to the Formation of Gas Porosity in Grey Cast Iron: Investigation of Core Gas Evolution and Gas Concentrations in Molten Iron

    Författare :Jessica Orlenius; Chalmers University of Technology; []
    Nyckelord :core binders; Gas porosity; hydrogen; grey iron; gas absorption; nitrogen; oxygen; gas evolution rate; green sand; mould filling; gas volume; gas solubility;

    Sammanfattning : Since gas porosity is a major casting problem, it is of greatest importance to increase the knowledge about the foundry process in order to minimise the presence of gas porosity and thereby improving the casting quality. Gas porosity is generally considered to originate from gases precipitated during solidification of iron and from entrained gas picked up by the metal during the mould filling. LÄS MER