Sökning: "entropy"

Visar resultat 11 - 15 av 318 avhandlingar innehållade ordet entropy.

  1. 11. Calculations of Reaction Mechanisms and Entropic Effects in Enzyme Catalysis

    Författare :Masoud Kazemi; Johan Åqvist; Per E. M. Siegbahn; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Enzyme catalysis; Entropy; Cytidine deamination; Ribosome; Peptidyl-tRNA hydrolysis; Peptide bond formation; Empirical valence bond method; Density functional theory; Biology with specialization in Structural Biology; Biologi med inriktning mot strukturbiologi; Biokemi; Biochemistry; Biology with specialization in Molecular Biotechnology; Biologi med inriktning mot molekylär bioteknik;

    Sammanfattning : Ground state destabilization is a hypothesis to explain enzyme catalysis. The most popular interpretation of it is the entropic effect, which states that enzymes accelerate biochemical reactions by bringing the reactants to a favorable position and orientation and the entropy cost of this is compensated by enthalpy of binding. LÄS MER

  3. 12. Microkinetic Modeling of Nanoparticle Catalysis using Density Functional Theory

    Författare :Mikkel Jørgensen; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Density Functional Theory; Methane oxidation; Mean-field approximation; Microkinetic modeling; Kinetic Monte Carlo; Nanoparticles; Entropy; CO oxidation; Catalysis;

    Sammanfattning : Heterogeneous catalysis is vitally important to modern society, and one path towardsrational catalyst design is through atomistic scale understanding. The atomistic scalecan be linked to macroscopic observables by microkinetic models based on first-principlescalculations. LÄS MER

  4. 13. On unequal probability sampling designs

    Författare :Anton Grafström; Lennart Bondesson; Sara De Luna; Imbi Traat; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; conditional Poisson sampling; correlated Poisson sampling; entropy; extended Sampford sampling; Horvitz-Thompson estimator; inclusion probabilities; list-sequential sampling; non-rejective implementation; Pareto sampling; Poisson sampling; probability functions; ratio estimator; real-time sampling; repeated Poisson sampling; Sampford sampling; sampling designs; splitting method; unequal probability sampling; Mathematical statistics; Matematisk statistik; Mathematical Statistics; matematisk statistik;

    Sammanfattning : The main objective in sampling is to select a sample from a population in order to estimate some unknown population parameter, usually a total or a mean of some interesting variable. When the units in the population do not have the same probability of being included in a sample, it is called unequal probability sampling. LÄS MER

  5. 14. Towards Measurable and Tunable Security

    Författare :Reine Lundin; Simone Fischer-Hubner; Stefan Lindskog; Viiveke Fåk; Karlstads universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; tunable security; security measures; metrics; entropy; guesswork; privacy; anonymity; selective encryption; Computer science; Datavetenskap; Datavetenskap; Computer Science;

    Sammanfattning : Many security services today only provides one security configuration at run-time, and cannot then utilize the trade-off between performance and security. In order to make use of this trade-off, tunable security services providing several security configurations that can be selected at run-time are needed. LÄS MER

  7. 15. Kinetics of Nanoparticle Catalysis from First Principles

    Författare :Mikkel Jørgensen; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; Density functional Theory; Mean field approximation; Acetylene hydrogenation; Kinetic Monte Carlo; CO oxidation; Entropy; Methane oxidation; Heterogeneous catalysis; Kinetic modeling; Nanoparticles;

    Sammanfattning : Modern society depends heavily on heterogeneous catalysis, which creates strong economical and environmental incentives to improve catalyst efficiency. Heterogeneous catalysts are often realized as metal nanoparticles (NPs) supported on oxide surfaces, and catalysts are traditionally developed by trial and error approaches. LÄS MER