Messung und Modulation membrannaher Prozesse in menschlichen Zellen mit optischen Methoden

Eine jede lebende Zelle hält an ihrer Plasmamembran ein elektrisches Ruhemembranpotential aufrecht, welches entscheidende Rollen u. a. bei der neuronalen Signalweiterleitung oder elektrogenen Transportprozessen einnimmt. In dieser Arbeit wurden dazu ratiometrische, genetisch codierte Spannungssensoren (rArc und rASAP) entwickelt, die in Kombination mit Verfahren zur automatisierten Hochdurchsatzmessung und Datenauswertung zur Bestimmung des zellulären Ruhemembranpotentials eingesetzt werden können. Mit den entwickelten Methoden konnte u. a. der hyperpolarisierende Effekt der ektopischen Expression krankheitsrelevanter Kaliumkanäle und Kaliumkanalmutanten auf das zelluläre Ruhemembranpotential nachgewiesen werden. Die Regulation des elektrischen Potentials der Plasmamembran wird maßgeblich über die Aktivität von Ionenkanälen bestimmt, die ihrerseits über intrazelluläre Signalmoleküle wie Ca2+, CO oder Fe2+ reguliert werden können. Es konnte gezeigt werden, dass das photolabile CO-freisetzende Molekül CORM-S1 auch als Fe2+-freisetzendes Molekül verwendet werden kann. CORM-S1 wurde in Kombination mit einer Blitzlichtquelle zur Erzeugung schneller Fe2+-Konzentrationssprünge eingesetzt und so die Geschwindigkeit der Fe2+-abhängigen Aktivitätsänderung von BKCa-Kaliumkanälen bestimmt. Signalprozesse über Signalmoleküle wie Ca2+ laufen häufig in räumlich stark begrenzten Bereichen ab. Hier wurden dazu aufwärtskonvertierende Nanopartikel (UCNPs), welche nahes Infrarotlicht in sichtbares bis ultraviolettes Licht umwandeln, auf ihre Eignung als lokale Quellen photochemischer Reaktionsnanodomänen untersucht. Als Modellsystem wurde die lokale Photokonversion des photokonvertierbaren Fluoreszenzproteins Dendra2 durch UCNPs untersucht. Mit diesem Modellsystem konnte gezeigt werden, dass molekular platzierte UCNPs zur räumlich begrenzten Manipulation von membrannahen Prozessen mit einer Auflösung weit unterhalb der Auflösungsgrenze klassischer Lichtmikroskopie geeignet sind

All-optical spatio-temporal control of electron emission from SiO2 nanospheres with femtosecond two-color laser fields

Field localization by nanostructures illuminated with laser pulses of well-defined waveform enables spatio-temporal tailoring of the near-fields for sub-cycle control of electron dynamics at the nanoscale. Here, we apply intense linearly-polarized two-color laser pulses for all-optical control of the highest energy electron emission from SiO2 nanoparticles. For the size regime where light propagation effects become important, we demonstrate the possibility to control the preferential emission angle of a considerable fraction of the fastest electrons by varying the relative phase of the two-color field. Trajectory based semi-classical simulations show that for the investigated nanoparticle size range the directional steering can be attributed to the two-color effect on the electron trajectories, while the accompanied modification of the spatial distribution of the ionization rate on the nanoparticle surface has only a minor effect

Few-cycle laser driven reaction nanoscopy on aerosolized silica nanoparticles

Nanoparticles offer unique properties as photocatalysts with large surface areas. Under irradiation with light, the associated near-fields can induce, enhance, and control molecular adsorbate reactions on the nanoscale. So far, however, there is no simple method available to spatially resolve the near-field induced reaction yield on the surface of nanoparticles. Here we close this gap by introducing reaction nanoscopy based on three-dimensional momentum-resolved photoionization. The technique is demonstrated for the spatially selective proton generation in few-cycle laser-induced dissociative ionization of ethanol and water on SiO2 nanoparticles, resolving a pronounced variation across the particle surface. The results are modeled and reproduced qualitatively by electrostatic and quasi-classical mean-field Mie Monte-Carlo (M3C) calculations. Reaction nanoscopy is suited for a wide range of isolated nanosystems and can provide spatially resolved ultrafast reaction dynamics on nanoparticles, clusters, and droplets

Few-cycle laser driven reaction nanoscopy on aerosolized silica nanoparticles

Nanoparticles offer unique properties as photocatalysts with large surface areas. Under irradiation with light, the associated near-fields can induce, enhance, and control molecular adsorbate reactions on the nanoscale. So far, however, there is no simple method available to spatially resolve the near-field induced reaction yield on the surface of nanoparticles. Here we close this gap by introducing reaction nanoscopy based on three-dimensional momentum-resolved photoionization. The technique is demonstrated for the spatially selective proton generation in few-cycle laser-induced dissociative ionization of ethanol and water on SiO2 nanoparticles, resolving a pronounced variation across the particle surface. The results are modeled and reproduced qualitatively by electrostatic and quasi-classical mean-field Mie Monte-Carlo (M3C) calculations. Reaction nanoscopy is suited for a wide range of isolated nanosystems and can provide spatially resolved ultrafast reaction dynamics on nanoparticles, clusters, and droplets

The individual relationship between atrial fibrillation sources from CARTOFINDER mapping and atrial cardiomyopathy: the catch me if you can trial

Background Targeting individual sources identified during atrial fibrillation (AF) has been used as an ablation strategy with varying results. Objective Aim of this study was to evaluate the relationship between regions of interest (ROIs) from CARTOFINDER (CF) mapping and atrial cardiomyopathy from late gadolinium enhancement (LGE) cardiovascular magnetic resonance imaging (CMR). Methods Twenty consecutive patients underwent index catheter ablation for persistent AF (PERS AF). Pre-processed LGE CMR images were merged with the results from CF mapping to visualize harboring regions for focal and rotational activities. Atrial cardiomyopathy was classified based on the four Utah stages. Results Procedural success was achieved in all patients (n = 20, 100%). LGE CMR revealed an intermediate amount of 21.41% ± 6.32% for LA fibrosis. ROIs were identified in all patients (mean no ROIs per patient n = 416.45 ± 204.57). A tendency towards a positive correlation between the total amount of atrial cardiomyopathy and the total number of ROIs per patient (regression coefficient, β = 10.86, p = .15) was observed. The degree of fibrosis and the presence of ROIs per segment showed no consistent spatial correlation (posterior: β = 0.36, p-value (p) = .24; anterior: β = −0.08, p = .54; lateral: β = 0.31, p = 39; septal: β = −0.12; p = .66; right PVs: β = 0.34, p = .27; left PVs: β = 0.07, p = .79; LAA: β = −0.91, p = .12). 12 months AF-free survival was 70% (n = 14) after ablation. Conclusion The presence of ROIs from CF mapping was not directly associated with the extent and location of fibrosis. Further studies evaluating the relationship between focal and rotational activity and atrial cardiomyopathy are mandatory

All-optical spatio-temporal control of electron emission from SiO2 nanospheres with femtosecond two-color laser fields

Field localization by nanostructures illuminated with laser pulses of well-defined waveform enables spatio-temporal tailoring of the near-fields for sub-cycle control of electron dynamics at the nanoscale. Here, we apply intense linearly-polarized two-color laser pulses for all-optical control of the highest energy electron emission from SiO2 nanoparticles. For the size regime where light propagation effects become important, we demonstrate the possibility to control the preferential emission angle of a considerable fraction of the fastest electrons by varying the relative phase of the two-color field. Trajectory based semi-classical simulations show that for the investigated nanoparticle size range the directional steering can be attributed to the two-color effect on the electron trajectories, while the accompanied modification of the spatial distribution of the ionization rate on the nanoparticle surface has only a minor effect. © 2019 The Author(s). Published by IOP Publishing Ltd on behalf of the Institute of Physics and Deutsche Physikalische Gesellschaf

Quenching of material dependence in few-cycle driven electron acceleration from nanoparticles under many-particle charge interaction

The excitation of nanoscale near-fields with ultrashort and intense laser pulses of well-defined waveform enables strongly spatially and temporally localized electron emission, opening up the possibility for the generation of attosecond electron pulses. Here, we investigate the electron photoemission from isolated nanoparticles of different materials in few-cycle laser fields at intensities where the Coulomb field of the ionized electrons and residual ions significantly contribute to the electron acceleration process. The dependences of the electron cut-off energy on the material’s dielectric properties and electron binding energy are investigated systematically in both experiments and semi-classical simulations. We find that for sufficiently high near-field intensities the material dependence of the acceleration in the enhanced near-fields is quenched by many-particle charge-interaction

Mobility in a Globalised World 2014

The term mobility has different meanings in the following science disciplines. In economics, mobility is the ability of an individual or a group to improve their economic status in relation to income and wealth within their lifetime or between generations. In information systems and computer science, mobility is used for the concept of mobile computing, in which a computer is transported by a person during normal use. Logistics creates by the design of logistics networks the infrastructure for the mobility of people and goods. Electric mobility is one of today’s solutions from engineering perspective to reduce the need of energy resources and environmental impact. Moreover, for urban planning, mobility is the crunch question about how to optimise the different needs for mobility and how to link different transportation systems. In this publication we collected the ideas of practitioners, researchers, and government officials regarding the different modes of mobility in a globalised world, focusing on both domestic and international issues

Le représentant Rühl fait part du civisme du citoyen Tramblez, de la section des Gardes-Françaises (Paris), au 9 thermidor, lors de la séance du 19 vendémiaire an III (10 octobre 1794)

Rühl Philipp jakob. Le représentant Rühl fait part du civisme du citoyen Tramblez, de la section des Gardes-Françaises (Paris), au 9 thermidor, lors de la séance du 19 vendémiaire an III (10 octobre 1794). In: Archives Parlementaires de 1787 à 1860 - Première série (1787-1799) Tome XCIX - Du 18 vendémiaire au 2 brumaire an III (9 au 23 octobre 1794) Paris : CNRS éditions, 1995. p. 42

Résultats de l'enquête du représentant Rühl, en mission dans les départements du Bas et du Haut-Rhin, sur la réception des lois et décrets ainsi que du Bulletin de la Convention, en annexe de la séance du 26 fructidor an II (12 septembre 1794)

Rühl Philipp jakob. Résultats de l'enquête du représentant Rühl, en mission dans les départements du Bas et du Haut-Rhin, sur la réception des lois et décrets ainsi que du Bulletin de la Convention, en annexe de la séance du 26 fructidor an II (12 septembre 1794). In: Archives Parlementaires de 1787 à 1860 - Première série (1787-1799) Tome XCVII - Du 23 fructidor an II au 2 vendémiaire an III (9 au 23 septembre 1794) Paris : CNRS éditions, 1993. pp. 125-130