Sökning: "chemical evolution"

Visar resultat 1 - 5 av 391 avhandlingar innehållade orden chemical evolution.

  1. 1. Stochastic Chemical Evolution : A Study of Scatter in Relative Elemental Abundances in Extremely Metal-poor Stars

    Författare :Torgny Karlsson; Bengt Gustafsson; Mike Edmunds; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; nucleosynthesis; chemical evolution; Galactic evolution; supernovae; chemical abundances; Population II stars; Astronomi; Astronomy and astrophysics; Astronomi och astrofysik;

    Sammanfattning : Chemical evolution addresses the problem of the formation of the chemical elements and their evolution throughout the history of the universe. This thesis discusses in particular the chemical evolution in the young universe and what we may learn from the observations of the oldest stars. LÄS MER

  3. 2. Modelling Evolution : From non-life, to life, to a variety of life

    Författare :Yu Liu; David J. T. Sumpter; Peter Dittrich; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Mathematical biology; Biocomplexity; Artificial chemistry; Ecosystem evolution; Origin of life; Self-replication; Prebiotic evolution; Collectively-catalytic; Golden ratio; Tillämpad matematik och statistik; Applied Mathematics and Statistics;

    Sammanfattning : Life is able to replicate itself, e.g., a microorganism is able to divide into two identical ones, and a single plant is able to forest a whole island. LÄS MER

  4. 3. Computational Protein Evolution : Modeling the Selectivity and Promiscuity of Engineered Enzymes

    Författare :Klaudia Szeler; Shina C. Lynn Kamerlin; Mikael Widersten; Maria Ramos; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; enzymes; kinetics; catalysis; density functional theory; empirical valence bond; diesters; evolution; promiscuity; Biokemi; Biochemistry;

    Sammanfattning : Enzymes are biological catalysts that significantly increase the rate of all biochemical reactions that take place within cells and are essential to maintain life. Many questions regarding their function remain unknown. LÄS MER

  5. 4. Theoretical and Experimental Studies of Electrode and Electrolyte Processes in Industrial Electrosynthesis

    Författare :Rasmus Karlsson; Ann Cornell; Jan Rossmeisl; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Electrocatalysis; metallic oxides; ruthenium dioxide; titanium dioxide; DSA; doping; selectivity; ab initio modeling; density functional theory; Elektrokatalys; metalloxider; ruteniumdioxid; titandioxid; DSA; dopning; selektivitet; ab initio-modellering; täthetsfunktionalteori; Chemical Engineering; Kemiteknik;

    Sammanfattning : Heterogeneous electrocatalysis is the usage of solid materials to decrease the amount of energy needed to produce chemicals using electricity. It is of core importance for modern life, as it enables production of chemicals, such as chlorine gas and sodium chlorate, needed for e.g. materials and pharmaceuticals production. LÄS MER

  7. 5. A tandem Catalyst for hydrogenation of CO2 to light olefins — The role of the zeolite component

    Författare :Wei Di; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Brønsted acid density; MTO reaction; CO2 hydrogenation; tandem catalysts; HCPs; methanol-intermediate; pre-coking; Al distribution; light olefins; SSZ-13 zeolite;

    Sammanfattning : The catalytic conversion of waste CO2 into light olefins offers a sustainable pathway for green chemicals production in the future. Over a tandem catalyst with the bifunctional active sites for methanol synthesis (CTM) and methanol to olefins (MTO), CO2 can be efficiently converted via intermediate methanol into a mixture of light olefins (ethylene, propene, butene). LÄS MER