المؤلفون: L. Uranga-Piña, A. Martínez-Mesa, Lídice Cruz-Rodríguez, Christoph Meier

المصدر: Chemical Physics Letters. 715:211-216

مصطلحات موضوعية: Physics, 010304 chemical physics, Quantum dynamics, General Physics and Astronomy, 02 engineering and technology, Hydrogen atom, Electron, Photoionization, 021001 nanoscience & nanotechnology, Laser, 01 natural sciences, law.invention, law, Ionization, 0103 physical sciences, Physics::Atomic Physics, Physical and Theoretical Chemistry, Atomic physics, 0210 nano-technology, Wave function, Quantum

الوصف: A methodology of quantum dynamics based on interacting trajectories without reference to any wave function is applied to ultrashort laser ionization of a model hydrogen atom. The pulses are chosen to be so short that the relative phase between the carrier wave and the pulse envelope becomes important. As main results we show that the trajectory-only approach is capable of correctly describing the large amplitude motion and energetics of the laser driven electron and of reproducing carrier-envelope effects onto the photoelectron spectra. It also provides an intuitive picture of the dynamical quantum processes involved.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::dc9756e2fe589b2163c4367838c1f7daTest
https://doi.org/10.1016/j.cplett.2018.11.031Test

المؤلفون: Christoph Meier, Lorenz Grimm, Andreas Ebneter, Dirk Theisen-Kunde, Boris Považay, Patrik Arnold, Christian Burri, Ralf Brinkmann, Alessa Hutfilz

المصدر: Medical Laser Applications and Laser-Tissue Interactions IX.

مصطلحات موضوعية: Retina, Retinal pigment epithelium, Materials science, genetic structures, medicine.diagnostic_test, Pulse (signal processing), Retinal, Laser, eye diseases, law.invention, chemistry.chemical_compound, Microsecond, medicine.anatomical_structure, chemistry, Optical coherence tomography, law, medicine, Microbubbles, sense organs, Biomedical engineering

الوصف: Selective retina therapy (SRT) is a short pulse (μs-regime) alternative to conventional laser photocoagulation (LPC) for treatment of retinal diseases. LPC leads to collateral damage of retinal layers adjacent to the retinal pigment epithelium (RPE), including healthy, non-regenerative photoreceptors due to the high thermal load, whereas in SRT, RPE cells are destroyed by microbubbles without damaging the neuronal retina. A novel experimental SRT laser operating at 532 nm wavelength can deliver 2 – 20 μs pulse sequences. Its tight integration into an upgraded diagnostic SPECTRALIS system combines beam control for treatment planning with real-time optical coherence tomography (OCT) overexposure protection of the photoreceptors. This “Spectralis Centaurus” system, was built and preliminary tested on porcine ex-vivo samples, reaching an unprecedented accuracy with unique planning and follow-up capabilities for upcoming clinical cellular level micro-surgery. The combination of OCT with SRT selectively limits cell death to the RPE by precisely controlling energy deposition while optically monitoring tissue response.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::ea3a2370a25f00b48d91b7a305e2ba06Test
https://doi.org/10.1117/12.2526720Test

المؤلفون: Alessa Hutfilz, Christoph Meier, Ralf Brinkmann, Christian Burri

المصدر: Medical Laser Applications and Laser-Tissue Interactions IX.

مصطلحات موضوعية: Retina, Retinal pigment epithelium, Materials science, Pulse (signal processing), Pulse duration, Laser, medicine.disease, law.invention, medicine.anatomical_structure, law, Fiber laser, medicine, sense organs, Intensity modulation, Cell damage, Biomedical engineering

الوصف: Selective retina therapy (SRT) is currently used in clinical studies to treat several chorioretinal diseases. For SRT a laser pulse duration of 1,7 µs is currently used. At this pulse duration the retinal pigment epithelium (RPE) cells are destroyed by transient microbubbles without damaging the neuronal retina. So far it is unclear whether slightly longer laser pulses are still acting thermomechanically or whether thermal effects show responsible for cell damage close above damage threshold. In order to investigate the damage threshold increase with pulse duration, a novel laser with adjustable pulse duration in the range of 2-20 µs was used to investigate RPE damage on ex-vivo porcine RPE explants. The specimen were fixed in an eye model and were exposed to laser pulse energies ranging from 15-150 µJ with a top hat square of 120x120µm², exhibiting a spatial intensity modulation factor of 1,3. Viability tests using binary evaluation result in threshold values with peak radiant exposures of 233 mJ/cm2 and 389 mJ/cm2 for 2 µs and 20 µs laser durations, respectively. An almost logarithmic increase of the threshold radiant exposure over pulse duration was found.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::2b9ef48fc87a217094a8d99d9cb5eee1Test
https://doi.org/10.1117/12.2526948Test

المؤلفون: Jörn Justiz, Daniel Kaufmann, Christoph Meier, Volker M. Koch, Boris Považay, Patrik Arnold, Christian Burri

مصطلحات موضوعية: genetic structures, media_common.quotation_subject, 01 natural sciences, Article, law.invention, 010309 optics, 03 medical and health sciences, chemistry.chemical_compound, 0302 clinical medicine, Optical coherence tomography, law, 0103 physical sciences, Dosimetry, Medicine, Contrast (vision), media_common, Retina, Retinal pigment epithelium, medicine.diagnostic_test, Pulse (signal processing), business.industry, Retinal, Laser, Atomic and Molecular Physics, and Optics, eye diseases, medicine.anatomical_structure, chemistry, 030221 ophthalmology & optometry, sense organs, business, Biotechnology, Biomedical engineering

الوصف: Selective treatment of the retinal pigment epithelium (RPE) by using short-pulse lasers leads to a less destructive treatment for certain retinal diseases in contrast to conventional photocoagulation. The introduction of selective retina therapy (SRT) to clinical routine is still precluded by the challenges to reliably monitor treatment success and to automatically adjust dose within the locally varying therapeutic window. Combining micrometer-scale depth resolving capabilities of optical coherence tomography (OCT) with SRT can yield real-time information on the laser-induced changes within the RPE after a laser pulse or even during treatment with a laser pulse train. In the present study, SRT and OCT were combined to treat ex-vivo porcine eyes demonstrating closed-loop dose-control. We found a reliable correlation of specific signal changes in time resolved OCT images and physiological lesions in the RPE. First experiments, including 23 porcine eyes, prove the feasibility of the novel treatment concept.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::8e868d339f9f37179f159af6d87ebe14Test
https://europepmc.org/articles/PMC6033566Test/

المؤلفون: Cong-Zhang Gao, Christoph Meier, Eric Suraud, Phuong Mai Dinh, Paul-Gerhard Reinhard

المساهمون: Systèmes de Fermions Finis - Agrégats (LPT), Laboratoire de Physique Théorique (LPT), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées, Institut für Theoretische Physik, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Théorie (LCAR), Laboratoire Collisions Agrégats Réactivité (LCAR), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)

المصدر: Physical Review A
Physical Review A, American Physical Society, 2017, 95, pp.033427. ⟨10.1103/PhysRevA.95.033427⟩

مصطلحات موضوعية: Physics, media_common.quotation_subject, [PHYS.PHYS.PHYS-ATM-PH]Physics [physics]/Physics [physics]/Atomic and Molecular Clusters [physics.atm-clus], Jellium, FOS: Physical sciences, Angle-resolved photoemission spectroscopy, Electron, Laser, 01 natural sciences, 7. Clean energy, Asymmetry, 010305 fluids & plasmas, 3. Good health, law.invention, law, Excited state, 0103 physical sciences, Physics - Atomic and Molecular Clusters, Sensitivity (control systems), Atomic physics, Atomic and Molecular Clusters (physics.atm-clus), 010306 general physics, ComputingMilieux_MISCELLANEOUS, Energy (signal processing), media_common

الوصف: We theoretically analyze angle-resolved photo-electron spectra (ARPES) generated by the interaction of C$_{60}$ with intense, short laser pulses. In particular, we focus on the impact of the carrier-envelope phase (CEP) onto the angular distribution. The electronic dynamics is described by time-dependent density functional theory, and the ionic background of $\csixty$ is approximated by a particularly designed jellium model. Our results show a clear dependence of the angular distributions onto the CEP for very short pulses covering only very few laser cycles, which disappears for longer pulses. For the specific laser parameters used in a recent experiments, a very good agreement is obtained. Furthermore, the asymmetry is found to depend on the energy of the emitted photoelectrons. The strong influence of the angular asymmetry of electron emission onto the CEP and pulse duration suggests to use this sensitivity as a means to analyze the structure of few-cycle laser pulses.
8 pages, 6 figures

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::c270a6ebe874cc15dd7dd194604fecc9Test
https://doi.org/10.1103/physreva.95.033427Test

المؤلفون: Christoph Meier, Arunangshu Debnath, Cyril Falvo

المساهمون: Théorie (LCAR), Laboratoire Collisions Agrégats Réactivité (LCAR), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées, Institut des Sciences Moléculaires d'Orsay (ISMO), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)

المصدر: Journal of Physical Chemistry A
Journal of Physical Chemistry A, American Chemical Society, 2013, 117 (48), pp.12884-12888. ⟨10.1021/jp410473u⟩

مصطلحات موضوعية: DYNAMICS, POLARIZATION, HEME POCKET, RELAXATION, 010402 general chemistry, 01 natural sciences, MOLECULAR DISSOCIATION, MYOGLOBIN, Spectral line, law.invention, ENERGY, law, 0103 physical sciences, Ultrafast laser spectroscopy, VIBRATIONAL-EXCITATION, Vibrational energy relaxation, Physical and Theoretical Chemistry, 010304 chemical physics, Chemistry, Relaxation (NMR), Laser, Pulse shaping, 0104 chemical sciences, Coherent control, COHERENT CONTROL, Atomic physics, ULTRAFAST INFRARED-SPECTROSCOPY, Excitation

الوصف: International audience; We present simulations of the excitation of specific vibrational levels of the CO stretch in carboxyhemoglobin by shaped mid-IR laser pulses. The pulses are calculated using local control theory, adapted to account for the protein fluctuations, which are included using a microscopic model developed previously. We show that efficient selective vibrational state preparation can be obtained, despite the presence of the fluctuations and orientational averaging, and can be monitored using transient absorption spectra. The mid-IR pulses are found to be in a realistic intensity regime and might soon be available by IR pulse shaping. This opens the way to a direct monitoring of vibrational relaxation from individually prepared, high-lying vibrational states of complex systems.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::9f182a7dab6eaa6d0dbfd71424460f24Test
https://doi.org/10.1021/jp410473uTest

المؤلفون: Oleksandr Astakhov, Alexander Schnegg, Klaus Lips, Christoph Meier, Robert Bittl, Christian Teutloff, Jan Behrends

المصدر: Journal of Magnetic Resonance. 234:1-9

مصطلحات موضوعية: Solar cells, Nuclear and High Energy Physics, Materials science, Silicon, Electrically detected magnetic resonance, Biophysics, Analytical chemistry, Resonance, chemistry.chemical_element, Condensed Matter Physics, Biochemistry, Molecular physics, Spectral line, Multi-frequency EDMR, Amorphous solid, law.invention, Paramagnetism, Microcrystalline, chemistry, law, Electron spin resonance, Microcrystalline silicon, Thin film, Electron paramagnetic resonance

الوصف: Pulsed multi-frequency electrically detected magnetic resonance (EDMR) at X-, Q- and W-Band (9.7, 34, and 94 GHz) was applied to investigate paramagnetic centers in microcrystalline silicon thin-film solar cells under illumination. The EDMR spectra are decomposed into resonances of conduction band tail states (e states) and phosphorus donor states (P states) from the amorphous layer and localized states near the conduction band (CE states) in the microcrystalline layer. The e resonance has a symmetric profile at all three frequencies, whereas the CE resonance reveals an asymmetry especially at W-band. This is suggested to be due to a size distribution of Si crystallites in the microcrystalline material. A gain in spectral resolution for the e and CE resonances at high fields and frequencies demonstrates the advantages of high-field EDMR for investigating devices of disordered Si. The microwave frequency independence of the EDMR spectra indicates that a spin-dependent process independent of thermal spin-polarization is responsible for the EDMR signals observed at X-, Q- and W-band.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::84e63fcd96619b878ec219593557b868Test
https://doi.org/10.1016/j.jmr.2013.06.002Test

المؤلفون: Robert Bittl, Jan Behrends, Christoph Meier

المصدر: Molecular Physics. 111:2683-2689

مصطلحات موضوعية: Rabi cycle, Chemistry, Biophysics, Condensed Matter Physics, law.invention, Paramagnetism, Microcrystalline silicon, law, Solar cell, Thin film solar cell, Physical and Theoretical Chemistry, Atomic physics, Spin (physics), Molecular Biology, Microwave, Rabi frequency

الوصف: The microscopic structure of light-activated paramagnetic conduction band tail states and their participation in spin-dependent hopping transport is studied in a microcrystalline silicon thin-film solar cell. Application of X- and S-band electrically detected magnetic resonance (EDMR) experiments in combination with numerical simulations of Rabi oscillations indicates that the spin-dependent process takes place between two neighbouring band tail states. For sufficiently high microwave (mw) power, two Rabi frequencies Ω1 and Ω2 = 2Ω1 show up in the coherent EDMR signals. An analysis of their relative contributions to the Rabi traces suggests that the g-values of both spin partners are not correlated for the majority of the EDMR-active pairs. A small fraction of doublet pairs with similar g-values may explain the appearance of a larger Ω2 contribution than predicted by the simulations.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::0701b4654f18293c6788b768fcc2defcTest
https://doi.org/10.1080/00268976.2013.820361Test

المؤلفون: Jonathan M. Grimes, Joanne E. Nettleship, Rene Assenberg, David I. Stuart, Thomas S. Walter, Kin Fai Au, Christoph Meier, Raymond J. Owens, Anil Verma, Jingshan Ren

المصدر: Structure (London, England : 1993)

مصطلحات موضوعية: Models, Molecular, Protein Conformation, Reductive methylation, Lysine, X ray instrumentation, Crystallography, X-Ray, Biochemistry, Methylation, Article, law.invention, Cohort Studies, 03 medical and health sciences, Protein structure, law, Structural Biology, Humans, Crystallization, Molecular Biology, 030304 developmental biology, 0303 health sciences, Murine hepatitis virus, Chemistry, Flavivirus, 030302 biochemistry & molecular biology, Chemical modification, Computational Biology, Proteins, Bacillus anthracis, Protein crystallization

الوصف: Summary Crystallization remains a critical step in X-ray structure determination. Because it is not generally possible to rationally predict crystallization conditions, commercial screens have been developed which sample a wide range of crystallization space. While this approach has proved successful in many cases, a significant number of proteins fail to crystallize despite being soluble and monodispersed. It is established that chemical modification can facilitate the crystallization of otherwise intractable proteins. Here we describe a method for the reductive methylation of lysine residues which is simple, inexpensive, and efficient, and report on its application to ten proteins. We describe the effect of methylation on the physico-chemical properties of these proteins, and show that it led to diffraction-quality crystals from four proteins and structures for three that had hitherto proved refractory to crystallization. The method is suited to both low- and high-throughput laboratories.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::3a8bd3c9e9061e5acf235baa2f314738Test
https://doi.org/10.1016/j.str.2006.09.005Test

المؤلفون: Dietmar Filsinger, Christoph Meier, Marco Leonetti, M. Kreschel, Michael Bargende, H. Schulze

المصدر: Proceedings ISBN: 9783658132545

مصطلحات موضوعية: Noise, Bearing (mechanical), Rotor (electric), law, Pressure control, Environmental science, Exhaust gas, Gas compressor, Automotive engineering, law.invention, Petrol engine, Turbocharger

الوصف: Emissions and fuel consumption are key development goals in modern vehicle engines. To use down-sizing and down-speeding the best way, an optimized charging strategy for the combustion engine is necessary. Due to their higher overall efficiency, compared with mechanical charging systems, exhaust gas turbocharging has become a technical standard of today’s vehicle engines. Especially in the upper and middle class vehicles the acoustic comfort is an important unique selling point and must not be affected by turbocharging. The constant tone is one of the relevant noise phenomena of turbochargers. His origins are natural-modes of the rotor radial bearings. Because of that an experimental investigation is significantly more complex in comparison with other noises at the turbocharger. The investigations are carried out on a turbocharger of a 2.0l gasoline engine with a waste-gate for boost pressure control. The turbocharger is mounted acoustic-decoupled from the engine to avoid unwanted interactions which distorts the results. Displacement sensors were applied inside turbocharger housing and were used to measure the displacement path of the rotor on compressor- and turbine-side. Also sensors to measure the radial bearing bush speeds are applied. The studies show a direct relationship between the rotational speeds of the floating bush bearing and the constant-tone phenomenon in air- and structure-borne noise. Simultaneous to the constant-tone occurrence also a change in the oscillation mode of the rotor can be observed. Furthermore the influence of the oil temperature, the oil supply pressure and the air mass flow were investigated.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::a4994b32c47530d410432e834fa484b6Test
https://doi.org/10.1007/978-3-658-13255-2_112Test