Refine
Year of publication
Document Type
- Doctoral Thesis (130)
- Article (98)
- Conference Proceeding (17)
Language
- English (245) (remove)
Has Fulltext
- yes (245)
Is part of the Bibliography
- no (245)
Keywords
- - (78)
- Plasma (23)
- Plasmaphysik (22)
- Stellarator (13)
- Plasmadiagnostik (10)
- Komplexes Plasma (7)
- Wendelstein 7-X (7)
- Cluster (6)
- Kernfusion (6)
- dusty plasma (6)
- Ionenfalle (5)
- Metallcluster (5)
- barrier discharge (5)
- Atmosphärendruckplasma (4)
- Divertor (4)
- Fusion (4)
- Fusionsplasma (4)
- Hochfrequenzplasma (4)
- Massenspektrometrie (4)
- Modellierung (4)
- Penningfalle (4)
- Physik (4)
- Plasmachemie (4)
- Polyanion (4)
- Simulation (4)
- Spektroskopie (4)
- magnetron sputtering (4)
- plasma (4)
- stellarator (4)
- surface charge (4)
- 52.70.Ds (3)
- Absorptionsspektroskopie (3)
- Aluminium (3)
- Clusterion (3)
- Dissertation (3)
- Festkörperphysik (3)
- Flugzeitspektrometrie (3)
- Gasentladung (3)
- Kernphysik (3)
- Laserinduzierte Fluoreszenz (3)
- Laserspektroskopie (3)
- Niedertemperaturplasma (3)
- Penning trap (3)
- Plasma Physics (3)
- Plasma-Wand-Wechselwirkung (3)
- Plasmadynamik (3)
- Plasmamedizin (3)
- Plasmarandschicht (3)
- Polyelektrolyt (3)
- Quantenoptik (3)
- Tokamak (3)
- Turbulenz (3)
- laser spectroscopy (3)
- mass separation (3)
- negative ions (3)
- oxygen (3)
- plasma diagnostics (3)
- polyanion (3)
- tokamak (3)
- 3D (2)
- Alfvén-Welle (2)
- Anion (2)
- Barrierenentladung (2)
- Cardiolipin (2)
- Clusterphysik (2)
- Computerphysik (2)
- Diffusion (2)
- Driftwelle (2)
- Dynamik (2)
- Emissionsspektroskopie (2)
- FT-IR-Spektroskopie (2)
- FTIR spectroscopy (2)
- Festkörper (2)
- Floquet (2)
- Flugzeitmassenspektrometrie (2)
- Fragmentation (2)
- Fullerene (2)
- Fusionsreaktor (2)
- Graphen (2)
- Heißes Plasma (2)
- Impurities (2)
- Infrarotspektroskopie (2)
- Instabilität (2)
- Kaltes Plasma (2)
- Kernstruktur (2)
- Laser (2)
- Leuchtstofflampe (2)
- Low Temperature Plasma (2)
- MR-ToF MS (2)
- MR-ToF device (2)
- Magnetfeld (2)
- Magnetic Confinement (2)
- Magnetische Rekonnexion (2)
- Magnetohydrodynamik (2)
- Magnetron (2)
- Monte-Carlo-Simulation (2)
- Multi-reflection time-of-flight mass spectrometry (2)
- Nuclear Physics (2)
- Optomechanik (2)
- Plasma physics (2)
- RNS (2)
- Rekonstruktion (2)
- Sekundärelektronen (2)
- Stereoskopie (2)
- Theoretische Physik (2)
- W7-AS (2)
- W7-X (2)
- atomic clusters (2)
- atomic force microscopy (2)
- cell mechanics (2)
- cold physical plasma (2)
- complex plasma (2)
- dusty plasmas (2)
- electrode (2)
- electron–hole plasma (2)
- erosion (2)
- gap voltage (2)
- guided streamer (2)
- inductively coupled plasma (2)
- ion mass spectrometry (2)
- ionosphere (2)
- laser photodetachment (2)
- laser-induced fluorescence (2)
- low temperature plasma (2)
- magnetic fields (2)
- mapping (2)
- memory effect (2)
- microwave interferometry (2)
- mode transition (2)
- numerical simulation (2)
- plasma chemistry (2)
- plasma medicine (2)
- polyelectrolyte multilayer (2)
- pre-ionization (2)
- reconstruction (2)
- solar EUV (2)
- stereoscopy (2)
- topologische Isolatoren (2)
- turbulence (2)
- 4D flow MRI (1)
- 52.27.Lw (1)
- 52.50.Dg (1)
- 52.65.-y (1)
- 52.75.Hn (1)
- 52.80.Hc (1)
- 7755384-6 (1)
- 89.75.Fb (1)
- ARPES (1)
- ASDEX (1)
- ASDEX Upgrade (1)
- Ab-initio-Rechnung (1)
- Abregung (1)
- Absorption Spectroscopy (1)
- Adsorption (1)
- Alfven (1)
- Alfvén Waves (1)
- Algorithm (1)
- Algorithmen (1)
- Algorithmus (1)
- Aluminium Cluster (1)
- Aluminium cluster (1)
- Aminogruppe (1)
- Anode (1)
- Antikoagulans (1)
- Antrieb (1)
- Argon metastables (1)
- Artificial nerual networks (1)
- Astrophysik (1)
- Atmospheric pressure plasma (1)
- Atmosphärendruckentladung (1)
- Atomemissionsspektroskopie (1)
- Atomspektrum (1)
- Auftrittsgröße (1)
- BAM (1)
- Barium (1)
- Bayes'sche Datenanalyse (1)
- Bayes-Verfahren (1)
- Bayesian Data Analysis (1)
- Beam (1)
- Biasing (1)
- Biomechanics (1)
- Biomolecules (1)
- Blei (1)
- Bogenentladung (1)
- Boltzmann equation (1)
- Bootstrap current (1)
- Bose-Einstein Kondensation (1)
- Bose-Einstein condensation (1)
- Bose-Einstein-Kondensation (1)
- Brennfleck (1)
- Brewster angle microscopy (1)
- Bürstenpolymere (1)
- CD Spektroskopie (1)
- Cadmium (1)
- Cavity Enhanced Absorption Spectroscopy (1)
- Cavity Ring-Down Spectroscopy (1)
- Cavity-Enhanced-Absorptionsspektroskopie (1)
- Cavity-Ring-Down-Spektroskopie (1)
- Cell biophysics (1)
- Cell cultures (1)
- Cell mechanics (1)
- Cell processes and subcellular processes (1)
- Cells (1)
- Cluster beam (1)
- Cluster charge (1)
- Cluster flow (1)
- Cluster formation (1)
- CoFeB (1)
- Coatings (1)
- Coil Optimization (1)
- Collisions (1)
- Colloidal Probe Technique (1)
- Complex plasma (1)
- Computersimulation (1)
- Connection length (1)
- Correlation Analysis (1)
- DBD (1)
- DIT (1)
- De-Excitation (1)
- Dense Plasmas (1)
- Density (1)
- Destabilisierung (1)
- Detachment (1)
- Diagnostik (1)
- Diamant (1)
- Dichte Plasmen (1)
- Dichtematrix (1)
- Dielectric Barrier Discharge (1)
- Dielektrische Entladung (1)
- Digital Ion Trap (1)
- Digital ion trap (1)
- Digitale Ionenfalle (1)
- Dirac-cone physics (1)
- Direct Force Measurement (1)
- Dispersion function (1)
- Dispersionsrelation (1)
- Dissipation (1)
- Domänen-Wachstum (1)
- Doppler cooling (1)
- Driftwellen (1)
- Duennschichten (1)
- Dust acoustic waves (1)
- Dusty Plasma (1)
- Dusty plasma (1)
- Dämpfung (1)
- Dünne Schicht (1)
- Dünne Schichten (1)
- Dünnes Plasma (1)
- ECRH (1)
- EEDF (1)
- EEVF (1)
- EPR (1)
- Edelgas (1)
- Effluent (1)
- Elastizität (1)
- Electric Propulsion (1)
- Elektrische Polarisation (1)
- Elektrode (1)
- Elektron (1)
- Elektronegative Plasmen / negative Ionen (1)
- Elektronenbad (1)
- Elektronenemission (1)
- Elektronenparamagnetische Resonanz (1)
- Emission (1)
- Emission Spectroscopy (1)
- Emitter (1)
- Empfindlichkeit (1)
- Energiereiches Teilchen (1)
- Entropie (1)
- Erosion (1)
- Escape factor (1)
- ExB-Drift (1)
- ExB-drift (1)
- Expansion (1)
- Exziton (1)
- FT-ICR-Spektroskopie (1)
- FTIR (1)
- FTIR-Spektrometrie (1)
- Far (1)
- Fast Particles (1)
- FeSe (1)
- Femtosecond lasers (1)
- Fernerkundung (1)
- Finite Systeme (1)
- Finite-element analysis (1)
- Fluid flows (1)
- Fluid-Modellierung (1)
- Fluorkohlenstoffhaltigen Plasmen (1)
- Fluorocarbon Plasmas (1)
- Flüssigkeiten (1)
- Fourier analysis (1)
- Fusion , Plasma , Plasmaphysik (1)
- Fusion plasma (1)
- Fusion plasmas (1)
- F‐actin (1)
- GPU computing (1)
- GaAs sputtering (1)
- Gas Cell (1)
- Gaselektronik (1)
- Gasphasenabscheidung (1)
- Gaszelle (1)
- Gaussian beam (1)
- Glass (1)
- Glimmentladung (1)
- Glimmentladungsspektroskopie (1)
- Graphene (1)
- Green-Funktion (1)
- Greenwald (1)
- Group (1)
- Guided Streamer (1)
- Gyro-kinetic Theory (1)
- Gyrokinetik (1)
- H-L back transition (1)
- Heat flux (1)
- Heat load (1)
- Heat-flux (1)
- Heparin (1)
- Heterostructures (1)
- Heterostrukturen (1)
- HiPIMS (1)
- High-Precision Mass Spectrometry (1)
- High-Temperature (1)
- Hoch Performanz (1)
- Hochfrequenzentladung (1)
- Hochfrequenzplasma / Plasmadynamik / Interferometrie / Photodetachment / Sauerstoff Plasma (1)
- Hot plasma (1)
- Hy (1)
- Hydrogen peroxide (1)
- Hydroperoxyl (1)
- IR-TDLAS (1)
- ISOLDE/CERN (1)
- ISOLTRAP (1)
- Informationstheorie (1)
- Infrarot (1)
- Infrarotabsorption (1)
- Innere Energie (1)
- Instrumentation for FEL (1)
- Instrumentation for radioactive beams (fragmentation devices, fragment and isotope, separators incl. ISOL, isobar separators, ion and atom traps, weak-beam diagnostics, radioactive-beam ion sources) (1)
- Ion Thruster (1)
- Ion Traps (1)
- Ion thrusters (1)
- Ion traps (1)
- Ionenbeschuss (1)
- Ionenfallen (1)
- Ionenstrahlfalle (1)
- Ionentriebwerk (1)
- Ionthruster (1)
- Isothermal Titration Calorimetry (1)
- Kalorimetrie (1)
- Kathode (1)
- Kerr microscopy (1)
- Kinetic Transport Theory (1)
- Kinetic simulation (1)
- Kinetische Gastheorie (1)
- Kinetische Theorie (1)
- Kinetische Transporttheorie (1)
- Kondo effect (1)
- Konformation (1)
- Kontaktmodell (1)
- Kontraktion (1)
- Kontrolle (1)
- Korrespondenzprinzip (1)
- Kraftmikroskopie (1)
- Künstliche Intelligenz (1)
- LE/LC phase transition (1)
- Laboratory experiment (1)
- Laboratory procedures (1)
- Laborexperiment (1)
- Ladungsdichtewelle (1)
- Ladungstransfer (1)
- Laminar flows (1)
- Langmuir Monolayers (1)
- Langmuir probe (1)
- Langmuir probe diagnostics (1)
- Langmuir-Blodgett and Schaefer techniques (1)
- Langmuir-Sonde (1)
- Laser spectroscopy (1)
- Laser-Cluster-Wechselwirkung (1)
- Laser-cluster interaction (1)
- Laser-induced fluoresence (LIF) (1)
- Laserheizung (1)
- Least-squares method (1)
- Lipid monolayers (1)
- Lipid-Monoschichten (1)
- Lipid-Oxidation (1)
- Low temperature plasma (1)
- Luftleuchten (1)
- L–H transition (1)
- MG-63 (1)
- MIR-Spektroskopie (1)
- Machine learning (1)
- Madden-Julian Oscillation (1)
- Magnetfelddiagnostik (1)
- Magnetic edge properties (1)
- Magnetic field diagnostics (1)
- Magnetic fields (1)
- Magnetic reconnection (1)
- Magnetische Rekonnektion (1)
- Magnetischer Einschluss (1)
- Magnetischer Sensor (1)
- Magnetismus (1)
- Magnetized (1)
- Magnetron sputtering (1)
- Marangoni flow (1)
- Mass Specrtometry (1)
- Mass spectrometers (1)
- Mass spectrometry (1)
- Master-Gleichung (1)
- Matrix (1)
- Mechanical properties (1)
- Mechanical stress (1)
- Mechanik (1)
- Mehrfach negativ geladene (1)
- Metall-Isolator-Phasenumwandlung (1)
- Microfluidic devices (1)
- Microfluidics (1)
- Microgravity (1)
- Microwave interferometry / Electron density / Laserphotodetachment (1)
- Mid-IR absorption spectroscopy (1)
- Mikrofluidik , Mechanik , Zelle , Holographie , Hologramm , Deformation , Biomedizin , Bluttransfusion , Cytometrie , Viskoelastizität (1)
- Mineral (1)
- Model Membranes (1)
- Modell (1)
- Modellbildung (1)
- Moden (1)
- Modendynamik (1)
- Modenübergang (1)
- Molecular Kinetics (1)
- Molekulardynamik (1)
- Molekülkinetik (1)
- Monoschicht (1)
- Multischicht (1)
- N incorporation (1)
- NBI (1)
- NEXT (1)
- Nachstellungsszenarien (1)
- Nachtluftleuchten (1)
- Nanocluster (1)
- Nanokompositschichten (1)
- Nanopartikel (1)
- Nanoplasmamodell (1)
- Negative ion (1)
- Neoclassical transport (1)
- Nerve cells (1)
- Neutral Beam Injection (1)
- Neutralisation (1)
- Neutralization (1)
- Neutrino (1)
- Neutronenbeugung (1)
- Neutronenstern (1)
- Nichtgleichgewicht (1)
- Nichtlineare Dynamik (1)
- Niederdruckplasma (1)
- Niedertemperatur-Plasma (1)
- Nuclear Structure (1)
- Nuclear fusion (1)
- Nukleosynthese (1)
- OLR-based MJO Index (1)
- OMI (1)
- Oberfläche (1)
- Oberflächenkräfte (1)
- Oberflächenladungen (1)
- Oberflächenmodifizierung (1)
- Oberflächenstöße (1)
- Operante Konditionierung (1)
- Optisches Messgerät (1)
- Oxidative stress (1)
- P3M (1)
- PDADMA (1)
- PEI,PDADMA,PSS,surface forces,atomic force microscopy, colloidal probe (1)
- PIC (1)
- PSS (1)
- PWV (1)
- Parallelstrom (1)
- Particle flux (1)
- Particle in Cell Simulation (1)
- Particle-in-Cell (1)
- Particle-in-cell (1)
- Particle-in-cell method (1)
- Paul-Falle (1)
- Penning Trap (1)
- Penning-Falle (1)
- Phase transitions (1)
- Phasenübergänge (1)
- Phospholipide (1)
- Phospholipids (1)
- Photoströme (1)
- Plasma , Plasmaphysik , Laser , Fluoreszenz , Interferometer , Wakefield , CERN , Kielfeld-Beschleuniger , Teilchenbeschleuniger , Laserinduzierte Fluoreszenz (1)
- Plasma , Plasmaphysik , Tokamak , Stellarator , Magnetohydrodynamik , Kinetische Theorie , Simulation , Alfvén-Welle , Energiereiches Teilchen (1)
- Plasma / Turbulenz (1)
- Plasma Chemistry (1)
- Plasma Instability (1)
- Plasma Modeling (1)
- Plasma Surface Interaction (1)
- Plasma diagnostics (1)
- Plasma diagnostics techniques and instrumentation (1)
- Plasma dynamics (1)
- Plasma medicine (1)
- Plasma surface interaction (1)
- Plasma-Flüssigkeits-Wechselwirkung (1)
- Plasma-Oberflächen-Wechselwirkung (1)
- Plasma-wall interaction (1)
- Plasmainstabilität (1)
- Plasmajet (1)
- Plasmanitrieren (1)
- Plasmaschwingung (1)
- Plasmasimulation (1)
- Plasmasonde (1)
- Plasmaspektroskopie (1)
- Plasmastrom (1)
- Plasmatheorie (1)
- Plasmatransport (1)
- Plasmawelle (1)
- Polarisation (1)
- Polaron (1)
- Polyanionen (1)
- Polyanions (1)
- Polydimethylsiloxan (1)
- Polyelektrolytbürste (1)
- Polymere (1)
- Polystyrolsulfonate (1)
- Potenzialhyperfläche (1)
- Power decay (1)
- Proteine (1)
- Präzisionsmassenmessung (1)
- Python (1)
- QCLAS (1)
- Quadrupole mass filter (1)
- Quantendot (1)
- Quantenkaskadenlaser (1)
- Quantenmechanik (1)
- Quantenphasenübergang (1)
- Quantenpunkt (1)
- Quantentheorie (1)
- Quantum Cascade Laser (1)
- RF Plasma (1)
- RF mass Spectrometry (1)
- ROS (1)
- ROS, cell and mitochondria mechanics (1)
- Radial axis shift (1)
- Radioactive Ion Beams (1)
- Radioaktivität (1)
- Radiofrequenz (1)
- Rasterkraftmikroskop (1)
- Rasterkraftmikroskopie (1)
- Reaktionsdynamik (1)
- Reinforcement learning (1)
- Relativistische Quantenmechanik (1)
- Relaxationskinetik (1)
- Renormalization (1)
- Robust (1)
- Rohstoffgewinnung (1)
- Rotational transform (1)
- Rydberg excitons (1)
- Röntgenbeugung (1)
- S/XB coefficient (1)
- Sauerstoff (1)
- Schadstoffabbau (1)
- Schaumflotation (1)
- Schlieren (1)
- Schnelles Teilchen (1)
- Schnittstelle (1)
- Schwerelosigkeit (1)
- Scrape-off layer width (1)
- Scraper (1)
- Secondary Electrons (1)
- Seebeck effect (1)
- Selbstorganisation (1)
- Self-absorption (1)
- Shape dynamics (1)
- Sheath transmission coefficient (1)
- Signal-to-noise ratio (1)
- Silber (1)
- Simulationsexperiment (1)
- Spectral imaging (1)
- Spectroscopy (1)
- Spin Trap (1)
- Spin Trapping (1)
- Spintronic devices (1)
- Spintronik (1)
- Sputterdeposition (1)
- Stark gekoppelte Systeme (1)
- Staub (1)
- Staubdichtewelle (1)
- Staubige Plasmen (1)
- Staubiges Plasma (1)
- Stickstoff (1)
- Stickstoff-Sauerstoff-Gemisch (1)
- Stickstoffgruppe (1)
- Stochstic Programming (1)
- Stoffwandlung (1)
- Stoß (1)
- Streutheorie (1)
- Strikeline (1)
- Sulfide (1)
- Supervised learning (1)
- Surface Collisions (1)
- Symmetrie (1)
- TDLAS (1)
- THz (1)
- TMCL (1)
- TOF (1)
- Temperatur (1)
- Terahertz radiation (1)
- Terahertz spectroscopy (1)
- Theoretical Physics (1)
- Thermografie (1)
- Thin films (1)
- Thrombozytopenie (1)
- Ti-Cu-N coating (1)
- Time-of-flight mass spectrometry (1)
- Titan Tholins (1)
- Titan-Tholine (1)
- Tomographie (1)
- Topologischer Isolator (1)
- Tracer particles (1)
- Tracerpartikel (1)
- Transmission electron microscopy (1)
- Transporttheorie (1)
- Turbulente Strömung (1)
- UV-VIS-Spektroskopie (1)
- VUV-Strahlung (1)
- Velocity distribution (1)
- Verdampfung (1)
- Verschränkung (1)
- Verunreinigungstransport (1)
- Vielteilchensystem (1)
- Vielteilchentheorie (1)
- Viscoelastic properties (1)
- Vorionisation (1)
- WSS (1)
- Wand-Abregung-Wahrscheinlichkeit (1)
- Waves (1)
- Wellen (1)
- Wellenmagnetfeld (1)
- Wellenwechselwirkung (1)
- Wendelstein (1)
- Wendelstein 7-x (1)
- Whistlerwelle (1)
- Wolfram (1)
- X-ray diffraction (1)
- X-ray photoelectron spectroscopy (1)
- Zeeman and Stark effects (1)
- Zeeman- und Stark-Effekte (1)
- Zelle (1)
- Zellmechanik (1)
- Zitterbewegung (1)
- absorption spectroscopy (1)
- actin cytoskeleton (1)
- actin quantification (1)
- airglow (1)
- alumina (1)
- amino polymer (1)
- anomal transport (1)
- anomaler Transport (1)
- anti-adhesive surface (1)
- antimatter plasma (1)
- aortic arch (1)
- appearance size (1)
- atherosclerosis (1)
- atmosphere (1)
- atmospheric pressure discharge (1)
- atmospheric pressure plasma (1)
- atomic level scheme (1)
- atomic masses of cesium isotopes (1)
- atomic spectra (1)
- barrier corona (BC) (1)
- bipolar pulse (1)
- borosilicate (1)
- calcium ion signaling (1)
- cathodes (1)
- cavity QED (1)
- cavity ring-down (1)
- cell adhesion (1)
- cell membrane (1)
- cell spreading (1)
- cell-material interaction (1)
- cell‐surface contacts (1)
- charge measurement (1)
- charge-density-wave (1)
- climate (1)
- cluster (1)
- cold atmospheric pressure plasmajet (1)
- combination therapy (1)
- complex plasmas (1)
- computer vision (1)
- consistent (1)
- contact model (1)
- control (1)
- copper nitride (1)
- correlation analysis (1)
- coupled phonon-plasmon modes (1)
- crystal structure (1)
- cylindrical wave (1)
- data-mining (1)
- density limit (1)
- diagnostics (1)
- dice lattice (1)
- dielectric barrier discharge (DBD) (1)
- dielectric response (1)
- dielektrisch behinderte Entladung (1)
- diffusion within multilayers (1)
- dipole magnetic field (1)
- discharge evolution (1)
- discharge mode transition (1)
- disruption (1)
- divertor (1)
- domain growth (1)
- drift waves (1)
- dust (1)
- dust charge (1)
- dust-density waves (1)
- electric field (1)
- electric propulsion (1)
- electrochemistry (1)
- electron bath (1)
- electron cyclotron emission (1)
- electron emission (1)
- electron energy loss spectroscopy (1)
- electronegativity (1)
- electronic structure (1)
- electron–positron plasma (1)
- ellipsometry (1)
- energetic ion (1)
- energy-resolved ion mass spectrometry (1)
- entanglement (1)
- entropy (1)
- evaporation (1)
- fast optical and electrical diagnostics (1)
- fdtd (1)
- finite difference in time domain (1)
- finite systems (1)
- flow dynamics (1)
- fluid modelling (1)
- fluid simulation (1)
- fluorescence (1)
- fluorescent lamp (1)
- fluorescent lamps (1)
- food quality (1)
- forcing (1)
- fractals (1)
- froth flotation (1)
- ftir spectroscopy (1)
- full-wave (1)
- fusion plasma (1)
- gas cell (1)
- gepulster Betrieb (1)
- glow-like discharge (1)
- glow-to-arc transition (1)
- gyrokinetic (1)
- gyrokinetics (1)
- gyrokinetisch (1)
- heavy actinides (1)
- helicon, fluorescence, accelerator (1)
- helium barrier discharge (1)
- helium–oxygen barrier discharge (1)
- high performance (1)
- high power impulse magnetron sputtering (1)
- high spatial resolution (1)
- hollow cathode discharge (1)
- hot spot (1)
- human osteoblasts (1)
- hydrogen peroxide (1)
- in situ (1)
- in-situ Diagnostik (1)
- inflammatory/immunological response (1)
- infrared spectroscopy (1)
- inhomogeneous plasma (1)
- inhomogenes plasma (1)
- instabilities (1)
- interchange (1)
- internal energy (1)
- intramuscularly implantation (1)
- intraseasonal variation (1)
- ion accelerator (1)
- ion composition (1)
- ion drag (1)
- ion traps (1)
- ion-beam trap (1)
- ionenwind (1)
- ionosphere modeling (1)
- ipf-fd3d (1)
- iron based superconductors (1)
- isotherms (1)
- kinetic modelling (1)
- konsistent (1)
- laser atomic absorption (1)
- laser heating (1)
- laser photodesorption (1)
- layer-by-layer (1)
- leafy greens (1)
- lebensdauerabhängige Auftrittsgrößen (1)
- lifetime-depentend appearance size (1)
- lipid domain growth (1)
- lipid monolayer (1)
- lipid oxidation (1)
- low-temperature plasma (1)
- low-temperature plasma polymerization (1)
- low‐temperature plasma (1)
- magic number (1)
- magnesia (1)
- magnetic characterization methods (1)
- magnetic field (1)
- magnetic materials (1)
- magnetic microscopy (1)
- magneto-hydrodynamic equilibrium (1)
- magneto-optical effects (1)
- magneto-optics (1)
- magnetron sputtering discharge (1)
- mass spectrometer (1)
- mass spectrometry (1)
- mathematical modeling (1)
- medical gas plasma technology (1)
- melamine-formaldehyde (1)
- metal-insulator transition (1)
- microcontact printing (1)
- microdischarge (1)
- microfluidics, cell mechanics, cells, holography, hologram, deformation, biomedicine, transfusion medicine, cytometry, viscoelasticity (1)
- microgravity research (1)
- microinstabilities (1)
- microinstabilitäten (1)
- microwave-driven discharge (1)
- mimic scenario (1)
- mixed-valence correlations (1)
- mode dynamics (1)
- modeling (1)
- modern experimental methods (1)
- molecular ion formation (1)
- monolayer (1)
- mouse (1)
- multi-reflection time-of-flight mass spectrometry (1)
- multilayer composition (1)
- multilayers (1)
- multiview geometry (1)
- mutlinucleon transfer (1)
- nanoparticles (1)
- nanosecond-pulsed streamer (1)
- nanowire (1)
- negative Ionen (1)
- nematicity (1)
- neoclassic (1)
- neoklassisch (1)
- networks (1)
- neural (1)
- neuron-rich calcium isotopes (1)
- neutral recycling (1)
- neutron reflectometry (1)
- neutron-rich nuclei (1)
- nicht-Hermitizität (1)
- nichtlinear (1)
- nightglow (1)
- nitrogen metastables (1)
- nitrogen-oxygen gas mixtures (1)
- non-Hermitian (1)
- non-equilibrium (1)
- non-thermal processing (1)
- nonlinear dynamics (1)
- numerische simulation (1)
- offene Quantensysteme (1)
- oncology (1)
- open quantum systems (1)
- optical diagnostics (1)
- optical emission and absorption spectroscopy (1)
- optical emission spectroscopy (1)
- optomechanics (1)
- osteoblasts (1)
- oxidation processes (1)
- pair plasma (1)
- parallel current (1)
- paramagnetic particles (1)
- partial discharge (PD) (1)
- partial mutual information (1)
- particle (1)
- particle tracking (1)
- particle transport (1)
- particle-in-cell (1)
- patterned discharge (1)
- penning trap mass spectrometer ISOLTRAP (1)
- permutation (1)
- phase resolved surface charge measurement (1)
- phase separation (1)
- phonon localization (1)
- phonon propagation (1)
- photocurrent (1)
- photodetachment spectroscopy (1)
- phototdissociation (1)
- pinch (1)
- plaque characteristics (1)
- plasma applications (1)
- plasma confinement (1)
- plasma current (1)
- plasma devices (1)
- plasma diagnostic (1)
- plasma in liquids (1)
- plasma instabilities (1)
- plasma jet (1)
- plasma material processing (1)
- plasma modeling (1)
- plasma physics (1)
- plasma science and technology (1)
- plasma sheaths (1)
- plasma simulation (1)
- plasma theory (1)
- plasma-fluorocarbon-polymer (1)
- plasma-liquid-interaction (1)
- platelet biomechanics (1)
- platelet cytoskeleton (1)
- plume (1)
- pollution control (1)
- polyelectrolyte (1)
- polyelectrolytes (1)
- positive Säule (1)
- positive column (1)
- positively biased anode (1)
- positron beam (1)
- precision mass measurements (1)
- pulse length dependence (1)
- pulsed laser deposition (1)
- pulsed operation (1)
- pulsed power (1)
- pump-probe spectroscopy (1)
- quantum cascade laser (1)
- quantum corrections (1)
- quantum phase transition (1)
- quasi-two-dimensional systems (1)
- r-Prozess (1)
- radiation detection (1)
- radioactive nuclei (1)
- reactive mode (1)
- reactive oxygen and nitrogen species (1)
- reactive oxygen species (1)
- ready-to-eat produce (1)
- real‐time deformability cytometry (1)
- remote (1)
- resistive ballooning (1)
- resonance ionization (1)
- retrieval (1)
- roadmap (1)
- rule changes (1)
- scanning ion conductance microscopy (1)
- scattering processes (1)
- schnelle optische und elektrische Diagnostik (1)
- scrape-off layer (1)
- secondary electron emission (1)
- secondary electron emission coefficient (1)
- secondary electrons (1)
- seed electrons (1)
- self-assembly (1)
- semi-empirical (1)
- sensitivity (1)
- separatrix (1)
- shear flow (1)
- short-lived nuclides (1)
- similarity laws (1)
- similarity scaling (1)
- simulation (1)
- simulations (1)
- skyrmions (1)
- solar variability (1)
- solenoid separator (1)
- solid-state physics (1)
- space charge (1)
- species conversion (1)
- spin-polarized current (1)
- statistical analysis (1)
- strain fields (1)
- strong correlations (1)
- superconductivity (1)
- superoxide anion (1)
- superposed epoch analysis (1)
- supported lipid bilayers (1)
- surface charge sensing (1)
- surface charges (1)
- surface double layer (1)
- surface electrons (1)
- surface forces (1)
- surface physics (1)
- symmetry (1)
- temperature (1)
- terahertz ellipsometry (1)
- terahertz emission spectroscopy (1)
- terahertz spintronics (1)
- terahertz time‐domain spectroscopy (1)
- terahertz transmission spectroscopy (1)
- theoretical description and modelling (1)
- thermionische Emission (1)
- thermography (1)
- thermosphere (1)
- thin film deposition (1)
- thin films (1)
- thrusters (1)
- time-correlated single photon counting (TC-SPC) (1)
- time-resolved optical emission spectroscopy (1)
- titanium (Ti) alloys (1)
- titanium surface modification (1)
- topological insulator (1)
- topological insulators (1)
- transient spark (1)
- transport coefficients (1)
- tumor immunology (1)
- tunable diode laser absorption spectroscopy (1)
- tungsten (1)
- two-photon absorption laser-induced fluorescence (1)
- ultrafast spincaloritronics (1)
- ultrafast spintronics (1)
- valleytronics (1)
- vision (1)
- voltage stabilization (1)
- wave interaction (1)
- wave magnetic field (1)
- weather forecasting (1)
- wettability (1)
- wetted area (1)
- whistler wave (1)
- zeta potential (1)
- zylindrische Welle (1)
- Überwachtes Lernen (1)
Institute
- Institut für Physik (245) (remove)
Publisher
- IOP Publishing (63)
- MDPI (13)
- Copernicus (7)
- AIP Publishing (6)
- Frontiers Media S.A. (4)
- Wiley (4)
- American Physical Society (APS) (3)
- Springer Nature (3)
- Cambridge University Press (2)
- European Geosciences Union (2)
In course of the recent results from Wendelstein 7-X, stellarators are on the brink for assessing their maturity as a fusion reactor. To this end, stellarator specific transport regimes need detailed exploration both with appropriate systematic experimental investigations and models. A way to enhance the efficiency of this process is seen in an systematic evaluation of existing experimental data. We propose appropriate tools developed in information theory for examining large datasets. Information entropy calculations, that have proven to assist the systematic assessment of datasets in many other scientific fields, are used for novelty detection.
Potentially, as a first use-case of this holistic process, this thesis attempts to link and to develop approaches to examine the stellarator specific core-electron-root-confinement (CERC) regime. The specific interest for CERC emerges from the behavior of the radial electric field. While ion-root conditions exhibit negative radial electric fields, CERC’s positive field in the very core of fusion grade plasmas adds an outward thermodynamic force to high-Z impurities and could add to potential actuators to control impurity influx as to be examined for full-metal wall operation in large stellarators. Recently, this feature received revived intent for reactor scale stellarators.
Also, in this work, parameter regions close to the transition from ion-root to CERC are
examined. At lower rotational transform (a characteristic feature of the magnetic field confining fusion grade plasmas), transitions were detected when the plasma current evolved. As in smaller stellarators, it is concluded that low-order rationals and magnetic islands are related to the transitions. This is widely supported by extensive MHD simulations which finally provide indications for the role of zonal flow oscillations. As one of the outcomes, gyrokinetic instabilities are seen interacting for the first time with the neoclassical mechanisms in experiments.
In order to cope with the vast number of highly sampled spatio-temporal plasma data, new
techniques for novelty detection are required. Fundamental prerequisites for the detailed
physics investigations were the feasibility study of entropy-based data analysis techniques, and their adaptation to detect previously unrevealed transition mechanisms. These tools were applied to multivariate bulk plasma emissivity data, which allowed the exploration of large parameter spaces and provided insights in the spatio-temporal dynamics of CERC transitions.
In this manner, this research highlights the feasibility of information flow measure analysis in fusion studies. Applications of different entropy-based complexity measures are explored and this work sheds light on the capabilities, added value and limitations of these techniques. This investigation presents the integration of information flow measures to gain deeper understanding of plasma transport phenomena, by providing an approach to fast systematic data mining suited for real-time analysis. This work paves the way for further development and implementation of information-theoretic methods for plasma data analysis.
In summary, this research highlights the gained insight on CERC transitions, while showcasing the feasibility, added values and limitations of information flow measure analysis for fusion studies, to induce theory based analysis revealing new insights in fundamental, stellarator-specific transport mechanisms.
The combination of the Layer-by-Layer (LbL) method, a nano-material such as carbon nanotubes (CNTs), and charged polyelectrolytes (PEs) is a reliable approach to produce highly functionalized surface coatings. These coatings are stable, controllable, ultra-thin, and most importantly, biocompatible. The ability to tune their properties by varying the preparation conditions and the terminating layer opens up a wide range of applications in the fields of biology and medicine. Here, the goal was to create electrically conductive coatings on which cells grow and proliferate. To achieve this goal, a coating with a stable conductive film structure, a suitable film surface topography, and suitable surface potential (and 𝜁-potential) must be prepared.
At the beginning of this thesis, the focus was on the fabrication of electrically conductive multilayer films, whose electrical properties should be stable and adjustable in a controlled manner (Article 1). The combination of chemically modified CNTs as polyanions, a strong linear polycation like poly(diallyldimethylammonium chloride) (PDADMA), and the LbL-method allowed us to prepare such films. Their characterization was carried out in air at ambient conditions. Since PDADMA is non-conductive, the charge transfer within the film and thus the electrical conductivity itself depends mainly on the CNTs and their arrangement. It was found that four CNT/PDADMA bilayers (BL) were always necessary to create a lateral network structure with multiple CNT crossing points to enable and support electron transport within the film. Moreover, additional CNT/PDADMA BL resulted in decreasing sheet resistance, while the conductivity remained constant at ≈ 4 kS/m regardless of the number of bilayers. Increasing the PDADMA molecular weight (Mw) from 44.4 kDa to 322 kDa did not affect film properties such as thickness or electrical conductivity.
However, increasing the CNT concentration from 0.15 mg/ml to 0.25 mg/ml in the deposition suspension resulted in thicker and less conductive films. This is attributed to a faster adsorption process of the CNTs leading to more adsorption sites for the polycation. We found an increased PDADMA monomer/CNT ratio compared to films prepared with the lower CNT concentration in the deposition suspension. The electrical conductivity decreased by a factor of four down to 1.1 kS/m, which can be attributed to fewer contact points between the CNTs. Overall, we were able to prepare stable and electrically conductive multilayer films. Additionally, by varying the preparation conditions tuning of the electrical conductivity is possible.
To fulfill requirements regarding i.e., medical implants, film properties not only have to be stable and controllable in a dry state (described in Article 1) but also in a biological aqueous environment. Therefore, in Article 2 we immersed our coated samples in three different solutions usually employed in biological research and compared their properties with their dry state, respectively. Also, hydration/swelling effects that normally occur for polyelectrolyte multilayer films (PEMs) in solutions were investigated.
For the film preparation, PDADMA (Mw = 322 kDa) and a deposition suspension of modified CNTs with two different concentrations (0.15 mg/ml and 0.25 mg/ml), which aged for two years, were used. Independent of the CNT suspension concentration, it turned out that the film thickness of the samples, prepared from the aged suspension, decreased significantly compared to the film thickness previously measured in Article 1. As a cross-check a new and fresh CNT suspension was made, which allowed us to reproduce the film thickness described in Article 1.
These results indicated that something happened with the CNT suspension over a two-year period. An analysis via X-ray photoelectron spectroscopy (XPS) showed a decrease in the percentage of functional groups in the CNTs from the aged suspension. The loss of functional groups resulted in less negatively charged CNTs and thus in fewer adsorption sites for the polycation PDADMA. Consequently, the PDADMA monomer/CNT ratio decreased, which lowered the thickness per bilayer by a factor of three, compared to films prepared with a freshly prepared CNT suspension. The lower linear charge density of the aged CNTs also enhanced their hydrophobicity, which is, in combination with the electrostatic forces, another important factor for multilayer cohesion. In contrast to PEMs made from polycations and polyanions, no swelling of the films occurred when immersed in solutions. This can be attributed to the fact that the increased hydrophobicity of the CNTs and the hydrophobic nature of the PDADMA backbone prevent the incorporation of water into the multilayer film. In solution, the films slightly shrink (by ≈ 2 nm), which makes them even more compact. Yet they remain stable. The result is an increased electrical conductivity from 9.6 kS/m, in the dry state, up to 15.3 kS/m immersed in solutions. To summarize, we showed that by tuning the interpolyelectrolyte forces the swelling and the ensuing decrease of the electrical conductivity of the films can be prevented.
Regarding the application in biology and medicine, we must consider that long-term exposure of cells to nano-materials like CNTs could lead to damage and inflammation of adjacent tissue. Therefore, it is necessary to prevent direct contact between the electrically conductive multilayer, i.e., CNT/PDADMA film, and the cells. The solution to this problem is a biocompatible top film that covers the CNT/PDADMA multilayer completely and still provides a lateral surface structure that supports cell adhesion and proliferation. Additional layers consisting solely of PEs could provide such a top film.
In Article 3 we investigated the self-patterning of PEM films as function of deposition steps. After preparation in water, the films were dried, characterized in air, and in vacuum. The films were built with high and low molecular weight PEs. PDADMA was used as polycation and poly(styrene sulfonate) sodium salt (PSS) as polyanion. The observation via Atomic Force Microscopy (AFM) showed that films prepared with high molecular weight PEs are laterally homogeneous and form no patterns, due to the chain immobility. The flat surfaces are ineligible as a substrate for cell adhesion.
In contrast, films built with a short PSS, especially at Mw, PSS = 10.7 kDa, began to self-pattern after seven deposited PDADMA/PSS bilayers. With each additionally deposited bilayer, the surface got more and more structured, from grooves over stripes to circular domains. Increasing film thickness led to an increased lateral mean distance between the surface structures. Scanning Electron Microscopy (SEM) images showed that exposure to a vacuum resulted in a decrease in the film thickness attributed to water removal, while the mean distance between the domains increased. Thus, by using this self-pattering process we are able to prepare PEMs with a highly structured surface. By adding PDADMA/PSS bilayers, not only the CNT/PDADMA film can be covered completely, but also a suitable surface morphology for cells can be created. Controlling the number of deposited bilayers allows the preparation of suitable coatings for cells.
To further improve the interaction of the cell and coated substrate not only the lateral structure but also the interacting electrostatic forces between cells and substrate are important for the nature of cell adhesion, function, and proliferation. In Article 4 we investigated PEMs, consisting of strong PEs with a low (PDADMA) and high (PSS) linear charge density. We performed asymmetric force measurements with the help of the colloidal probe technique (CP). Here, the forces between a PEM-covered surface and a colloidal probe (silica sphere) glued to a cantilever were investigated. The colloidal probe was either bare or covered with polycation poly(ethylenimine) (PEI). The surfaces were immersed in NaCl solutions with different ionic strengths (INaCl), starting with deionized water, then enriched up to 1 mol/L NaCl. The interaction force between a CP and the surface was measured. Thus, insight into the surface potential/charge was obtained.
During film preparation, two growth regimes (parabolic and linear) exist. These regimes and the terminating layer determine the surface force of the PEM. PEMs with a terminating PSS layer are predominantly flat and negatively charged when the ion concentration is low and the film is in the parabolic growth regime (between 1 and ≈ 15 BL). This indicates charge reversal on PSS adsorption. At the transition point between the parabolic and linear growth regimes, the ratio between polyanion and polycation monomers starts to switch and some cationic monomers are neutralized not by anionic monomers but by monovalent ions. Therefore, the surface charge density in diluted NaCl solutions changed from slightly positive near the transition to positive in the linear growth regime. At the lowest ionic strengths (INaCL) the range of the surface potential goes from – 40.5 mV (9 BL, parabolic) up to + 50 mV (19 BL, linear).
In contrast, polycation (PDADMA) terminated films are overall positive in diluted NaCl solutions. At the beginning of the parabolic growth regime, the layers are more compact and flat. However, with each additional layer deposited, the film becomes less compact and the chains begin to loosen. The now more loosely bound chains start to protrude into the solution and form pseudo-brushes. This could already be observed for 10.5 BL.
It intensifies in the linear growth regime (begin at ≈ 15 BL) and results in steric surface forces. Changing the surrounding INaCl affects this behavior and the pseudo-brushes scale as polyelectrolyte brushes.
By controlling the number of bilayers (thus the growth regime), the surrounding ionic strength, and the conformation of PEs at the PEM surface, it is possible to prepare a suitable range of surface properties i.e., for cell adhesion and proliferation. To prove that these multilayers can provide a suitable surface and have a positive effect on cell behavior, we coated in Article 5 titanium-covered samples with PEMs. Investigated was the cell interaction with the surface at different zeta(ζ) - potentials, a parameter for dynamic surface potential. Here the cell activity is measured by the mobilization of calcium (Ca2+) within the cell as a function of the ζ - potential of the substrate and the externally applied electrical potential. The cell activity indicates if the ζ - potential, provided by the sample surface, is suitable or not for the cells. The favorable interaction with the substrate is also reflected in the cell morphology and proliferation. The results showed that highly negative ζ - potentials between - 90 and - 3 mV led to a decreasing/reduced Ca2+ mobilization which correlates with reduced cell activity. Nearly neutral to moderate positive surfaces (ζ - potential + 1 to + 10 mV) i.e., PSS-terminated PEMs are able to promote cell adhesion and growth as demonstrated by an increased Ca2+ mobilization. The access to the intracellular Ca2+ stores, provided by the external stimulus, is now more effective and suggests a higher cell activity. Increasing the ζ - potentials up to ≈ + 50 mV (highly positive), i.e., PDADMA - terminated PEMs with pseudo-brushes, resulted in restricted cell viability and impaired Ca2+ mobilization, which led to a disturbed cell morphology and proliferation. In conclusion, only surfaces, terminated with i.e., PEI, with moderate positive charges (ζ - potential + 1 to + 10 mV) are able to improve the Ca2+ mobilization and thus the cell activity and proliferation. PEMs with a PSS termination provide negative 𝜁−potentials, onto which cells adhere, and proliferate. Therefore, they are a good alternative for surface functionalization for implant surfaces. In summary, the objective set at the beginning of the thesis is addressed within articles written as part of this thesis. It is possible to fabricate PEMs with modified CNTs to produce coatings that are electrically conductive with tunable sheet resistance, whether dry in air or immersed in an aqueous solution (Articles 1 and 2). Also, for pure PEMs, it is shown that with the right molecular weight of PEs and a certain number of bilayers, a suitable surface structure for cell adhesion can be produced (Article 3). Additional surface properties such as a suitable surface charge density can be provided by PEMs which can improve the cell activity as monitored with Ca2+ mobilization (Articles 4 and 5). The next step is to combine the knowledge gained from Articles 1 – 5 and link it to the application of external electrical fields to cells.
In this work, 2-dimensional measurements in the THz frequency range with self-made spintronic THz emitters were presented. The STE were used to optimize the spatial resolution and determine the magnetization in geometric shapes. At the beginning, various combinations of FM and NM layers were produced and measured to achieve an optimal composition of the STE. The layer thickness of the ferromagnetic CoFeB layer and the nonmagnetic PT layer was also varied. The investigations have shown that a layer combination of 2 nm thick CoFeB and 2 nm thick Pt, applied to a fused silica glass substrate and covered with a 300 nm thick SiO2 layer, emits the highest THz amplitude. Based on these, a structured sample, consisting of an STE and an additional layer system of 5 nm Cr and 100 nm Au, was produced. Further, three wedge-shaped structures were removed from the gold layer by an etching process so that the THz radiation generated by the STE can pass through these areas. This enables the optimization of the resolution of the system. For this purpose, the sample was moved perpendicular to the laser beam by two stepping motors with a step size of 5 μm and imaged 2-dimensionally. By reducing the step size to 0.2 μm, the beam diameter could be measured at the edge of the structure using the knife-edge method. Based on this measurement, the resolution of the system could be determined as 5.1 ± 0.5 μm at 0.5 THz, 4.9 ± 0.4 μm at 1 THz, and 5.0 ± 0.5 μm at 1.5 THz. These results are confirmed by simulations considering the propagation of THz wave packets through the SiO2. The expansion of the FWHM of the waves, passing through the 300 nm thick layer, is about 1%. Only a SiO2 layer with a thickness in the μm range occurs an expansion of around 10%. This shows that it is possible to perform 2-dimensional THz spectroscopy with a resolution in the dimension of the exciting laser beam by using near-field optics. Afterward, the achieved spatial resolution was used to investigate the influence of external magnetic fields on the STE and the emitted THz radiation. By implementing a pair of coils above the sample, an external magnetic field could be applied parallel to the pattern. The used sample was designed in such a way that only certain geometric areas on the fused silica glass substrate were coated with an STE so that THz radiation is emitted only in those areas. The 2-dimensional images show the geometric structures for f = 1.0 THz and f = 1.5 THz clearly. By applying a permanent, positive magnetic field (+M), a positive course of the THz amplitude can be seen. A rotation of the magnetic field by 180° (-M) leads to a reversal of the orientation of the emitted THz radiation, whereby the magnetic field does not influence the corresponding frequency spectrum. By using minor loops, the sample was demagnetized by the constant reduction of the magnetic field strength with alternating magnetic field direction. The 2-dimensional representation of the pattern with a step size of 10 μm shows that the sample was demagnetized since both, positively and negatively magnetized structures, could be imaged. In addition, in the 2nd row from the top, a completely demagnetized circle and a rectangle with a division into two domains can be seen. These structures have both positive and negative magnetized areas, which are separated by a domain wall. To investigate this in more detail a 2-dimensional measurement of the divided regions was made with a step size of 2.5 μm. These images confirm the division of the structures into positive and negative domains, separated by a domain wall, which was verified by Kerr-microscope measurements. Both data show a similar course of the domains and the domain wall. However, to be able to examine the domain wall more precisely using 2-dimensional THz spectroscopy, the resolution of the system must be improved to a range of a few nm, because the expected domain wall width is between 𝑙𝑊 = 12.56 nm and 𝑙𝑊 = 125.6 nm. The improved resolution would make it possible to image foreign objects, such as microplastics in biological cells or tissue. For this purpose, different plastics, such as polypropylene, polyethylene, and polystyrene, were investigated in the THz frequency range up to 4 THz. While no specific absorption could be determined for PP, characteristic absorption peaks were found for PE and PS. The energy of the photons with a frequency of about 2.2 THz excites lattice vibrations in the PE. Therefore, this frequency is specifically absorbed, and the intensity in the transmission spectrum is lower than for other frequencies. PS absorbs especially THz radiation with a frequency of 3.2 THz. In addition, all of the investigated plastics are mostly transparent for THz radiation, which makes imaging of these materials feasible. Based on these basic properties, it will be possible to image and identify these types of plastic.
Interplay of reactive oxygen species with the mechanical properties of cells and mitochondria
(2023)
Cell mechanical properties are a popular label-free method for understanding basic cellular processes. In this thesis, I used Real-time deformability cytometry (RT-DC), a high-throughput microfluidic technology, to investigate the mechanical properties of cells and mitochondria under various conditions such as increased reactive oxygen species (ROS) levels and the application of different ligand coated gold nano-particles (Au-Nps) effect on cells. Initially, we showed the possibility to measure organelles, cells, and tissue-like structures (spheroids) in a single system by constructing a virtual fluidic channel. We investigated a potential application using cytochalasin D (cyto D) treatment, which revealed increased deformation and decreased stiffness in both the normal and virtual channels. Using mechanics as a marker, I investigated the effect of excessive ROS on the mechanical properties of human myeloid precursor cells (HL60). My findings suggest that the mechanical response of HL60 cells to increased ROS levels is mediated by re-localization of microtubules toward the cell center and F-actin to the cell periphery. Interestingly, I also observed intracellular acidification, which is a largely unexplored mechanism that may have contributed to our findings. I then extended our ROS and mechanics assay to investigate cell-AuNP interactions, demonstrating that cell properties vary depending on the cell culture media and ligand coating. The results showed that dextran coated gold nano-particels (Au-Nps) had low cytotoxicity, lower ROS release, and no change in cell mechanics, indicating a potential application for dextran Au NPs. Finally, I expanded our assays to include high-throughput microfluidic characterization of isolated mitochondria. Using both exogenously and endogenously induced ROS, we found an increase in mitochondrial deformation and a decrease in their size, which could have implications on mitochondrial function, i.e., fission and fusion. We believe that advanced applications of RT-DC technology will improve the comparability of results across different sample sizes while also promoting it as a disease detection technique.
Graphene is a strictly two-dimensional honeycomb lattice of carbon atoms whose low-energy charge-carrier dynamics obey the massless pseudospin-1/2 Dirac-Weyl equation (or chiral Weyl equation) where the chiral centers (or valleys) are the corners K and K‘ of the Brillouin zone. The linear spectrum near the Dirac nodal points lends graphene its exotic and ultra-relativistic properties.
However, condensed matter systems can possess fermionic excitations with linear dispersions that have no analog in high-energy physics since the crystal space group - instead of the Poincare group - constrains the energy dispersions. Perhaps the first example in this regard is the T_3 lattice (Dice Gitter), a honeycomb-like lattice with an extra atom placed at the center of each hexagon and coupled to only one of the sublattices. The spectrum features a strictly flat band that crosses the two conical intersections of the Dirac cones at K and K' inherited from graphene. The enlarged pseudospin-1 Dirac-Weyl equation describes the low-energy dynamics. By rescaling the transfer amplitude of the additional atoms in the T_3 lattice with a parameter 0<α<1, the resulting α-T_3 lattice continously interpolates between graphene and the T_3 lattice.
In this work, we explore the behavior of generalized Dirac-Weyl quasiparticles in external magnetic and valley-dependent pseudoelectromagnetic fields induced by out-of-plane strain. First, we studied Dirac-Weyl quasiparticles in external fields confined to circular quantum dots by generalizing the infinite-mass boundary condition to the α-T_3 lattices. We verified the analytically derived valley-anisotropic eigenstates of the quantum dot by numerically solving the tight-binding lattice-model in closed (isolated) and open (contacted) systems.
Second, we considered strain fields in the α-T_3 lattices to modify the low-energy transport properties by an effective pseudo-gauge field with opposite signs at the K and K‘ valley. In particular, we showed that the inhomogeneous pseudomagnetic field generated by Gaussian out-of-plane strain at the center of a four-terminal Hall bar setup acts as a valley filter. Most interestingly, the valley polarization is most dominant when incoming electrons are excited to pseudo-Landau level subbands. These bands are linked to different iso-field orbits encircling the lobes of the pseudomagnetic field. Addittionaly, any intermediate α breaks the inversion symmetry of the α-T_3 lattice and thus splits the pseudo-Landau levels into sublattice-polarized bands.
Third, we equipped the out-of-plane strain with a time-periodic drive to induce a valley-dependent pseudoelectric field perpendicular to the pseudomagnetic field. We assessed the steady-state transport properties and found – besides the static regime for small energies – two α-dependent valley-filtering regimes due to the periodic drive. Firstly, we found an additional valley-polarization plateau at the Floquet-zone boundary between the central and first Floquet copy that also displayed a “flower”-like pattern in the local density of states. Secondly, we detected a series of transmission gaps at the center of every Floquet sideband 2mΩ related to the Floquet coupling of the flat band with the central Floquet copy. Under certain strain parameters, a novel valley-filtering regime appears near the transmission gaps where the incoming K electrons are focused through the bump by the pseudoelectric field, instead of encircling the lobes of the pseudomagnetic field. A stability analysis demonstrated that the polarization regimes are tunable by the driving frequency.
Lastly, we demonstrated that the flat band in the Haldane-dice lattice modified by a uniaxial strain along the zigzag orientation remains singular at all band crossings where the model undergoes a topological phase transition between C=+-2 and C=0. To show this, we computed the compact localized eigenstates and the quantum distance of the Bloch wave function around the band-touching points. We derived the resulting non-contractible loop states and an extended state whose components are tunabe by the system parameters.
This thesis presents the production of polyanionic clusters within two ion storage devices:
Considering a Penning trap, the accessible range of polyanionic aluminium clusters has been expanded up to the 10th charge state. In particular, abundance curves for clusters with 5 to 9 excess electrons have been measured for the first time and analysed with respect to their lifetime-dependent appearance sizes. These sizes reveal a nearly quadratic dependency on the charge state for experimentally accessible lifetimes.
Additionally, the production of polyanionic clusters has been enabled in a radiofrequency ion trap. Therefore, the transition from a harmonic to a digital 2- and 3-state guiding signal has been investigated with respect to the ion storage. The passing of electrons through the trap during field-free periods of the guiding signal led to the first production of polyanionic clusters within a radiofrequency ion trap.
Research into nuclear physics has enjoyed a long and rich history since the earliest experiments began investigating atomic constituents. The discovery of the atomic nucleus in the early 20th century started a complex field of research that has undergone many transformations with the advancements of modern technology. Today, atomic nuclei are not only studied to advance our understanding of the strong force but also to gain more information on the synthesis of elements in the universe, to exploit nuclear decay to investigate the weak interaction, and to search for physics beyond the standard model.
In this work, we will study the strong force in atomic nuclei, i.e. the way nucleons (protons and neutrons) arrange themselves in a many-body system governed by the repulsive Coulomb interaction and the attractive strong interaction. In particular, we will focus on nuclear structure near nuclei with a "magic number" of Z protons and N neutrons, so-called doubly-magic nuclei, exhibiting a particularly stable configuration with respect to neighboring nuclei.
Within the nuclear shell model, similar to the atomic shells, the magic numbers indicate shell closures accompanied by energy gaps. Nuclei at double-shell closures and their direct vicinity provide an important playground to benchmark nuclear theories and models that aim to predict the intricate interplay of the nucleons that lead to enhanced nuclear binding energies, significant changes in charge radii and transition strengths, etc.
Of particular interest are nuclear isomers, long-lived excited states, in which the nucleon configuration with respect to its ground state is altered, resulting in a modification of their properties despite having the same number of protons and neutrons.
The main part of this work consists of three publications, which report on nuclear structure investigations through mass measurements and laser spectroscopy near the doubly magic nuclei nickel-78, tin-100, and lead-208.
The nuclides investigated in this work include neutron-deficient indium isotopes, neutron-rich zinc isotopes, and neutron-rich mercury isotopes.
In this thesis, I was able to provide answers to transport processes in lipid monolayers, which are ultimately, all of biological relevance. In particular, I was interested in lipid oxidation and dynamic compression/expansion processes of surfactant monolayers at the air-water interface:
Lipid oxidation was shown to be a consequence of the formation of a high concentration of reactive oxygen species (ROS) during cell respiration, which finally can lead to severe cell damage. It is not yet understood clearly, which part of the lipid molecules is especially prone to a ROS attack. I was particularly interested in the role of the double bonds of the acyl chains of the lipid molecules during oxidation. Further, I wanted to know the time scales of lipid interaction with the ROS.
Compared to lipid vesicles, lipid monolayers have the advantage that many parameters of the system can be adjusted easily. In our system, I made use of this by setting the lateral pressure to low values during H2O2 treatment, which facilitated the ROS to reach the double bonds in the acyl chains.
A prime example of biological systems out of thermal equilibrium was given in the alveolus surface, which is covered with a surfactant monolayer. During breathing, these monolayers undergo such a highly dynamic compression and expansion. Arising flows from breathing could disrupt a film and consequently, it would lose its protective role. One of my goals was to understand flows and their influence on domain shape. Dependent on the strength of the flows, I expected different growth regimes, with differing prevailing transport processes. Once understanding the underlying mechanisms in domain shaping would allow me to draw conclusions on biological systems.
In order to address these questions, I established two systems, both based on the compression of lipid monolayers. I used isotherms to study the phase behavior of the lipids:9 During compression, the lipids can undergo phase transitions from the gaseous phase to the liquid expanded phase (LE-phase) and further from the LE-phase to the liquid condensed phase (LC-phase). A coexistence regime is observed in between the LE-phase and the LC-phase, characterized by a flat increase of lateral pressure with decreasing molecular area. Some lipids exhibited LC-phase domains. These were further investigated with Brewster angle microscopy (BAM). The used BAM was equipped with an integrated Scheimpflug optics, enabling an overall focused image plane. Furthermore, time-resolved observation of the growth of the domains was possible by recording videos (20 frames per seconds).
The first system enabled the investigation of lipid peroxidation, when the lipids were exposed to ROS. I chose DMPC, POPC, DOPC and PLPC, since these are phospholipids differing in the number and position of double bonds in acyl chains, but not in the head group. I used a H2O2 enriched phosphate buffered saline (PBS) solution, which served as a precursor for more reactive ROS, like hydroxyls (.OH). PBS was chosen, since it resembles the cell environment best. During defined waiting times of H2O2 treatment, the ROS diffused vertically from the subphase towards the monolayer. The lipid molecules were in the LE-phase, which facilitated the ROS molecules to reach also the double bonds of the acyl chains. The oxidized monolayers were then compressed at constant compression speed. Since the corresponding isotherms could be measured with high precision, the relative area increase δA/A between oxidized and non-oxidized monolayer along the isotherm proved to be a good measure for lipid peroxidation. The area increase δA in the molecular area of the oxidized molecules was explained by the eventually added, more hydrophilic −OOH group at the position of a carbon atom adjacent to a double bond in the unsaturated acyl chain. The −OOH group is drawn to the hydrophilic head group of the lipid. This leads to a kink in the acyl chain, which increases the molecular area A by δA. A model, which explained this peroxidation process in lipid vesicles, could be adopted to monolayers.
I compared the oxidation of phospholipids, differing in the number and position of the double bonds of their acyl chains. I found that δA/A increased with the growing number of double bonds in one acyl chain. However, a comparison of DOPC with POPC also showed the importance of the position of the acyl chain. I determined a slow reaction kinetic. It could be estimated by a √t dependence of the number density N_surface, which denominates the ROS sticking on the monolayer. The transport of ROS towards the monolayer was found to be diffusive, because it was the slowest process in the reaction. This interpretation was reinforced by a comparison of the temperature dependence of the relative area increase δA/A with the Stokes-Einstein diffusion coefficient of water molecules. The initial ROS concentration c_0 in the trough could be traced back (c_0~ 50 nM), which is indeed a realistic value found in human cells.
Concluding, our results can be understood as a feasibility study. The complexity of the monolayer can be arbitrarily increased, for example by the addition of proteins, allowing the investigation of other oxidative processes occurring in the cell membrane.
The second system allowed the investigation of growth of LC domains during fast compression processes of monolayers. I chose erucic acid monolayers, due to its low line tension and a continuous nucleation phase, enabling the formation of fractal domains. The monolayers were investigated with isotherms and BAM videos. Since v_C (compression speed of the monolayer) was continuous over the whole compression time, I had a system with well-defined hydrodynamic conditions. This allowed me a complete analysis of the system, starting with descriptive features of the observed domains to a classification of the observed growth regimes by means of hydrodynamic theory, through to the distinction and quantification of different kind of flows and supersaturations, involving Ivantsov theory:
Dependent on the compression speed v_C, I observed seaweed or dendritic domains. The LE/LC phase transition pressure pi_t was slightly increased compared to pi_inf of the equilibrium isotherm. A high compression speed v_C induced a supersaturation Δc. I introduced the excess lateral pressure Δpi=pi-pi_inf as an appropriate quantity to describe the supersaturation Δc. I showed a linear behavior of Δc on Δpi. Δc is a macroscopic quantity since it is averaged over the whole monolayer area. I characterized the domains of the seaweed and dendritic regime with respect to tip radii, branch lengths, side branch separations and fractal dimensions. I calculated the growth speed of the main branches. A roughly doubling of the growth speed of dendritic domains, compared to seaweed domains was observed. This was an evidence of adjunctive (Marangoni) flow in the subphase.
For each monolayer, I observed drifts during domain growth, which I explained by an anisotropy in the LE-phase, caused by the continuous nucleation of the domains. These kind of surface flows were superimposed to bulk flows in the subphase. Since I had a well established system, I could analyze the influence of these surface flows on domain shape, in terms of magnitude, direction and duration of the surface flows. I therefore used FFT spectra and directionality histograms. At low flows, the FFT showed six-fold symmetry. Higher drifts exhibited incisions in the FFT, eventually leading to dumbbell shaped FFTs at very high drifts. The domains grew preferentially in the direction parallel to the incision.
I used directionality histograms to analyze the angular distribution of the growing domains. They showed that the drift direction always correlated with a minimum in the histogram. In order to analyze drift duration, I split the domain in downstream and upstream side. I could show that for small drift durations, downstream growth was preferred. However, for longer drift durations, the flows got more isotropic and consequently growth was more balanced then.
I could observe only a weak correlation between drift velocity v_D and compression speed v_C. However, dendrites were formed when the compression speed v_C was high, while seaweed domains were formed when v_C was small. Domain distortion occurred in the same way, independent if seaweed or dendritic domains were considered. I further showed that hydrodynamic flows in the subphase and surface flows are superimposed and scale differently. Consequently, they have different impact on domain shape: hydrodynamic flows act on μm scale and influence the domain morphology (distance between side branches, and tip radius) and the growth speed of the main branches. Surface flows act on the mm to cm scale, cause an anisotropic flow in the LE phase surrounding the domain, and thus affect the overall domain shape.
The anisotropy in the LE-phase led to a locally different degree of supersaturation. To take this into account, I introduced a local normalized supersaturation Δ, based on the Ivantsov solution. Therefore, I calculated Péclet numbers p of measured quantities of the system. I obtained values of 0.88 ≤Δ≤0.90 for the seaweed regime (p<5) and 0.93 ≤Δ≤0.96 for the dendritic regime (p>6). Since the Ivantsov solution can only be applied for purely diffusive processes, I applied a modified Ivantsov solution Δ_mod, which calculates Δ at a distance 𝛿 ahead of the dendrite tip. I was able to determine the progression of the diffusive layer 𝛿, however a quantitative determination failed.
Applying hydrodynamic theory allowed me to classify the two growth regimes with respect to the Boussinesq number Bq. Since for both growth regimes, I achieved values of Bq<1, bulk viscous losses dominated over surface viscous losses. Further, a cross-over length 𝜉 was calculated, from which one can distinguish, whether advective transport dominates over diffusion.
I further connected the two defined supersaturations Δ and Δc via the excess lateral pressure Δpi. From this, I saw differences in the seaweed and dendritic growth regimes: The local normalized supersaturation Δ of seaweed growth seemed to be quite stable for a further increase of the lateral excess pressure Δpi, whereas it reacted quite sensitive in the dendritic regime. This was found to be an indication of a non-equilibrium regime, caused by the strong coupling of the monolayer to the subphase. It reinforces therefore the theory of Marangoni-flow.
The findings of this thesis emphasize the importance of understanding highly dynamic compression/expansion processes arising in surfactant monolayers. Using the example of the compression of the alveolus surface, it can be seen that a more realistic model of the pulmonary alveolus is not only enabled by increasing the complexity of the surfactant monolayer (e.g. by adding specific proteins or lipid mixtures to the monolayer). Equally important is the understanding in transport processes and the consequences for the monolayer structure. By the analysis of domain shapes, I presented a method, which is suitable for such a study.
In future fusion reactors disruptions must be avoided at all costs. Disruptions due to the density limit (DL) are typically described by the power-independent Greenwald scaling. Recently, a power dependence of the disruptive DL was predicted by several authors (Zanca et al 2019 Nucl. Fusion 59 126011; Giacomin et al 2022 Phys. Rev. Lett. 128 185003; Singh and Diamond 2022 Plasma Phys. Control. Fusion 64 084004; Stroth et al 2022 Nucl. Fusion 62 076008; Brown and Goldston 2021 Nucl. Mater. Energy 27 101002). It is investigated whether this increases the operational range of the tokamak. Increasing the heating power in the L-mode can induce an L-H transition, and therefore a power-dependent DL and the L-H transition cannot be considered independently. The different models are tested on a data base for separatrix parameters at the separatrix of ASDEX Upgrade and compared with the concept (SepOS) presented in Eich and Manz (2021 Nucl. Fusion 61 086017). The disruptive separatrix density scales with the power ne ∝ P0.38±0.08 in good agreement to all models. Also the back transition from high to low (H-L) confinement shows an approximately Greenwald scaling with an additional power dependence ne ∝ P0.4 according to the SepOS concept. For future devices operating at much higher heating power such a power scaling may allow operation at much higher separatrix densities than are common in H-mode operation. Preconditions to extrapolation for future devices are discussed.
The controlled formation and adjustment of size and density of magnetic skyrmions in Ta/CoFeB/MgO trilayers with low Dzyaloshinskii–Moriya interaction is demonstrated. Close to the out-of-plane to in-plane magnetic spin reorientation transition, we find that small energy contributions enable skyrmion formation in a narrow window of 20 pm in CoFeB thickness. Zero-field stable skyrmions are established with proper magnetic field initialization within a 10 pm CoFeB thickness range. Using magneto-optical imaging with quantitative image processing, variations in skyrmion distribution and diameter are analyzed quantitatively, the latter for sizes well below the optical resolution limit. We demonstrate the controlled merging of individual skyrmions. The overall demonstrated degree of comprehension of skyrmion control aids to the development of envisioned skyrmion based magnetic memory devices.