Institution
Technical University of Berlin
Education•Berlin, Germany•
About: Technical University of Berlin is a education organization based out in Berlin, Germany. It is known for research contribution in the topics: Quantum dot & Laser. The organization has 27292 authors who have published 59342 publications receiving 1414623 citations. The organization is also known as: Technische Universität Berlin & TU Berlin.
Topics: Quantum dot, Laser, Catalysis, Population, Raman spectroscopy
Papers published on a yearly basis
Papers
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TL;DR: A 330-metre core from the marine Permian/Triassic boundary in the Carnic Alps of Austria allows closely correlated studies of geochemistry, petrography and palaeontology across the boundary as mentioned in this paper.
Abstract: A 330-metre core drilled through the marine Permian/Triassic boundary in the Carnic Alps of Austria allows closely correlated studies of geochemistry, petrography and palaeontology across the boundary. The isotope shifts and metal concentrations are extended, multiple and complex, and do not resemble those seen at the Cretaceous/Tertiary boundary. Both the carbon isotope shifts and the chemical events (including an indium anomaly) may have causes related to a major regression of the sea.
270 citations
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TL;DR: It is indicated that argpyrimidine is synthesized through an intermediate 3-hydroxypentane-2,4-dione and provide a chemical basis for fluorescence in proteins modified by methylglyoxal, suggesting that it is a major product in such modified proteins.
270 citations
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TL;DR: Rabi oscillations renormalized and a damping that depends on the input pulse strength, a behavior not known from exponential dephasing mechanisms are found.
Abstract: Electron-phonon interaction is a major source of optical dephasing in semiconductor quantum dots. Within a density matrix theory the electron-phonon interaction is considered up to the second order of a correlation expansion, allowing the calculation of the quantum kinetic dephasing dynamics of optically induced nonlinearities in GaAs quantum dots for arbitrary pulse strengths and shapes. We find Rabi oscillations renormalized and a damping that depends on the input pulse strength, a behavior not known from exponential dephasing mechanisms.
270 citations
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15 Jun 1997TL;DR: Probing the protein structure by circular dichroism spectroscopy indicates that Teflon promotes the formation of helical structure in alpha-chymotrypsin, but the reverse effect is found with cutinase, and differential scanning calorimetry points to a heterogeneous population of adsorbed protein molecules with respect to their conformational states.
Abstract: A proteolytic enzyme, α-chymotrypsin, and a lipolytic enzyme, cutinase, were adsorbed from aqueous solution onto a hydrophobic Teflon surface and a hydrophilic silica surface. We investigated the influence of adsorption on the structure, the structure thermal stability and the activity of these enzymes. Probing the protein structure by circular dichroism spectroscopy indicates that Teflon promotes the formation of helical structure in α-chymotrypsin, but the reverse effect is found with cutinase. The perturbed protein structures on Teflon are remarkably stable, showing no heat-induced structural transitions up to 100°C, as monitored by differential scanning calorimetry. Contact with the hydrophilic silica surface leads to a loss in the helix content of both proteins. Differential scanning calorimetry points to a heterogeneous population of adsorbed protein molecules with respect to their conformational states. The fraction of the native-like conformation in the adsorbed layer increases with increasing coverage of the silica surface by the proteins. The specific enzymatic activity in the adsorbed state qualitatively correlates with the fraction of proteins in the native-like conformation.
269 citations
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TL;DR: It is revealed that the activity of Fe/N/C-catalysts prepared through a pyrolysis in NH3 is mostly imparted by acid-resistant FeN4-sites whose turnover frequency for the O2 reduction can be regulated by fine chemical changes of the catalyst surface.
Abstract: The high cost of proton-exchange-membrane fuel cells would be considerably reduced if platinum-based catalysts were replaced by iron-based substitutes, which have recently demonstrated comparable activity for oxygen reduction, but whose cause of activity decay in acidic medium has been elusive. Here, we reveal that the activity of Fe/N/C-catalysts prepared through a pyrolysis in NH3 is mostly imparted by acid-resistant FeN4-sites whose turnover frequency for the O2 reduction can be regulated by fine chemical changes of the catalyst surface. We show that surface N-groups protonate at pH 1 and subsequently bind anions. This results in decreased activity for the O2 reduction. The anions can be removed chemically or thermally, which restores the activity of acid-resistant FeN4-sites. These results are interpreted as an increased turnover frequency of FeN4-sites when specific surface N-groups protonate. These unprecedented findings provide new perspective for stabilizing the most active Fe/N/C-catalysts known to date.
269 citations
Authors
Showing all 27602 results
Name | H-index | Papers | Citations |
---|---|---|---|
Markus Antonietti | 176 | 1068 | 127235 |
Jian Li | 133 | 2863 | 87131 |
Klaus-Robert Müller | 129 | 764 | 79391 |
Michael Wagner | 124 | 351 | 54251 |
Shi Xue Dou | 122 | 2028 | 74031 |
Xinchen Wang | 120 | 349 | 65072 |
Michael S. Feld | 119 | 552 | 51968 |
Jian Liu | 117 | 2090 | 73156 |
Ary A. Hoffmann | 113 | 907 | 55354 |
Stefan Grimme | 113 | 680 | 105087 |
David M. Karl | 112 | 461 | 48702 |
Lester Packer | 112 | 751 | 63116 |
Andreas Heinz | 108 | 1078 | 45002 |
Horst Weller | 105 | 451 | 44273 |
G. Hughes | 103 | 957 | 46632 |