TY - JOUR AB - In this report, a flame spray pyrolysis setup has been examined with various in situ extraction methods of particle samples along the flame axis. First, two precursor formulations leading to the formation of iron oxide nanoparticles were used in a standardized SpraySyn burner system, and the final particle outcome was characterized by a broad range of established powder characterization techniques (TEM/HRTEM, SAXS, XRD, BET). The characterization of the powder products evidenced that mostly homogeneous gas-to-particle conversion takes place when applying an acidic precursor solution, whereas the absence of the acid leads to a dominant droplet-to-particle pathway. Our study indicates that a droplet-to-particle-pathway could be present even when processing the acidic formulation. However, even if a secondary pathway might take place in this case as well, it is not dominant and nearly negligible. Subsequently, the in situ particle structure evolution was investigated for the dominant gas-to-particle pathway, and particles were extracted along the flame axis for online SMPS and offline TEM/HRTEM analysis. Due to the highly reactive conditions within the flame (high temperatures, turbulent flow field, high particle number concentrations), the extraction of representative samples from spray flames is challenging. In order to handle the reactive conditions, two extraction techniques were tailored in this report. To extract an aerosol sample within the flame for SMPS measurement, a Hole in a Tube probe was adjusted. Thus, the mobility particle diameter as well as the corresponding distribution widths were obtained at different heights above the burner along the flame axis. For TEM/HRTEM image analysis, particle samples were collected thermophoretically by means of a tailored shutter system. Since all sampling grids were protected until reaching the flame axis and due to the low sampling time, momentary captures of local particle structures could be extracted precisely. The particle morphologies have clearly shown an evolution from spherical and paired particles in the flame center to fractal and compact agglomerates at later synthesis stages. AU - Tischendorf, R. AU - Simmler, M. AU - Weinberger, Christian AU - Bieber, M. AU - Reddemann, M. AU - Fröde, F. AU - Lindner, J. AU - Pitsch, H. AU - Kneer, R. AU - Tiemann, Michael AU - Nirschl, H. AU - Schmid, H.-J. ID - 25896 JF - Journal of Aerosol Science SN - 0021-8502 TI - Examination of the evolution of iron oxide nanoparticles in flame spray pyrolysis by tailored in situ particle sampling techniques ER - TY - JOUR AB - Photodynamic therapy (PDT) using TiO2 nanoparticles has become an important alternative treatment for different types of cancer due to their high photocatalytic activity and high absorption of UV-A light. To potentiate this treatment, we have coated commercial glass plates with TiO2 nanoparticles prepared by the sol–gel method (TiO2-m), which exhibit a remarkable selectivity for the irreversible trapping of cancer cells. The physicochemical properties of the deposited TiO2-m nanoparticle coatings have been characterized by a number of complementary surface-analytical techniques and their interaction with leukemia and healthy blood cells were investigated. Scanning electron and atomic force microscopy verify the formation of a compact layer of TiO2-m nanoparticles. The particles are predominantly in the anatase phase and have hydroxyl-terminated surfaces as revealed by Raman, X-ray photoelectron, and infrared spectroscopy, as well as X-ray diffraction. We find that lymphoblastic leukemia cells adhere to the TiO2-m coating and undergo amoeboid-like migration, whereas lymphocytic cells show distinctly weaker interactions with the coating. This evidences the potential of this nanomaterial coating to selectively trap cancer cells and renders it a promising candidate for the development of future prototypes of PDT devices for the treatment of leukemia and other types of cancers with non-adherent cells. AU - Garcia Diosa, Jaime Andres AU - Gonzalez Orive, Alejandro AU - Weinberger, Christian AU - Schwiderek, Sabrina AU - Knust, Steffen AU - Tiemann, Michael AU - Grundmeier, Guido AU - Keller, Adrian AU - Camargo Amado, Ruben Jesus ID - 22635 JF - Journal of Biomedical Materials Research Part B: Applied Biomaterials SN - 1552-4973 TI - TiO2 nanoparticle coatings on glass surfaces for the selective trapping of leukemia cells from peripheral blood VL - 109 ER - TY - JOUR AB - The tetratopic linker 1,1,2,2-tetrakis(4-phosphonophenyl)ethylene (H8TPPE) was used to synthesize the three new porous metal–organic frameworks of composition [M2(H2O)2(H2TPPE)]·xH2O (M = Al3+, Ga3+, Fe3+), denoted as M-CAU-53 under hydrothermal reaction conditions, using the corresponding metal nitrates as starting materials. The crystal structures of the compounds were determined ab initio from powder X-ray diffraction data, revealing small structural differences. Proton conductivity measurements were carried out, indicating different conductivity mechanisms. The differences in proton conductivity could be linked to the individual structures. In addition, a thorough characterization via thermogravimetry, elemental analysis, IR-spectroscopy as well as N2- and H2O-sorption is given. AU - Steinke, Felix AU - Javed, Ali AU - Wöhlbrandt, Stephan AU - Tiemann, Michael AU - Stock, Norbert ID - 25892 JF - Dalton Transactions SN - 1477-9226 TI - New isoreticular phosphonate MOFs based on a tetratopic linker ER - TY - CHAP AU - Eickelmann, Birgit ID - 29061 T2 - Chancen denken. Impulse für eine offene und mutige Gesellschaft im 21. Jahrhundert TI - Etwas anarchischer, freier, ungewohnter (Ein Gespräch mit Birgit Eickelmann) ER - TY - CHAP AU - Eickelmann, Birgit AU - Maaz, Kai ED - Maaz, Kai ED - Becker-Mrotzek, Michael ID - 29062 T2 - Schule weiter denken TI - Ungleichheiten im Bildungssystem – eine unangenehme Konstante. Sinnvolle Maßnahmen und die Grenzen des Möglichen ER - TY - GEN AU - Bonanati, Sabrina AU - Buhl, Heike M. AU - Eickelmann, Birgit ID - 29066 TI - Wie Lernen in digitalen Lernumgebungen motivieren kann – Stichwort: Gamification ER - TY - JOUR AB - Abstract Objective External focus (EF) of attention leads to improved balance performance. Consideration of the neuromodulatory effects of EF may inform its clinical utility in addressing neuroplastic impairments after musculoskeletal injuries. We aimed to determine whether electrocortical activity and balance performance changed with attentional foci that prioritized differing sensory feedback and whether changes in electrocortical activity and balance were associated. Methods Individuals who were healthy (n = 15) performed a single-limb balance task under 3 conditions: internal focus (IF), somatosensory focus [EF with a baton (EF-baton)], and visual focus [EF with a laser (EF-laser)]. Electrocortical activity and postural sway were recorded concurrently using electroencephalography and a triaxial force plate. Electroencephalographic signals were decomposed, localized, and clustered to generate power spectral density in θ and α-2 frequency bands. Postural sway signals were analyzed with center-of-pressure sway metrics (eg, area, distance, velocity) and knee angle. The relationship between percent change in clustered brain activity and task performance metrics was assessed. Results Both EF conditions resulted in increased cortical activity and improved balance performance compared to IF. EF-laser had the largest effect, demonstrating increased frontal θ power (d = 0.64), decreased central θ power (d = −0.30), and decreased bilateral motor, bilateral parietal, and occipital α-2 power (d = −1.38 to −4.27) as well as a shorter path distance (d = −0.94) and a deeper (d = 0.70) and less variable (d = −1.15) knee angle than IF. Weak to moderate associations exist between increases in cortical activity and improved balance performance (ρ = 0.405–0.584). Conclusions EF resulted in increased cortical activity associated with cognitive, motor, somatosensory, and visual processing. EF-laser, which prioritized visual feedback, had the largest and broadest effects. Changes in cortical activity resulting from EF were independently associated with improved balance performance. Impact This study demonstrates that goal-oriented attention results in functional increases in brain activity compared to internally directed self-focus. These results suggest EF may target neurophysiologic impairments and improve balance in clinical populations. AU - Sherman, David A AU - Lehmann, Tim AU - Baumeister, Jochen AU - Gokeler, Alli AU - Donovan, Luke AU - Norte, Grant E ID - 34024 JF - Physical Therapy KW - Physical Therapy KW - Sports Therapy and Rehabilitation SN - 0031-9023 TI - External Focus of Attention Influences Cortical Activity Associated with Single Limb Balance Performance ER - TY - JOUR AB - Whereas initial findings have already identified cortical patterns accompanying proprioceptive deficiencies in patients after anterior cruciate ligament reconstruction (ACLR), little is known about compensatory sensorimotor mechanisms for re-establishing postural control. Therefore, the aim of the present study was to explore leg dependent patterns of cortical contributions to postural control in patients 6 weeks following ACLR. A total of 12 patients after ACLR (25.1 ± 3.2 years, 178.1 ± 9.7 cm, 77.5 ± 14.4 kg) and another 12 gender, age, and activity matched healthy controls participated in this study. All subjects performed 10 × 30 s. single leg stances on each leg, equipped with 64-channel mobile electroencephalography (EEG). Postural stability was quantified by area of sway and sway velocity. Estimations of the weighted phase lag index were conducted as a cortical measure of functional connectivity. The findings showed significant group × leg interactions for increased functional connectivity in the anterior cruciate ligament (ACL) injured leg, predominantly including fronto−parietal [F(1, 22) = 8.41, p ≤ 0.008, η2 = 0.28], fronto−occipital [F(1, 22) = 4.43, p ≤ 0.047, η2 = 0.17], parieto−motor [F(1, 22) = 10.30, p ≤ 0.004, η2 = 0.32], occipito−motor [F(1, 22) = 5.21, p ≤ 0.032, η2 = 0.19], and occipito−parietal [F(1, 22) = 4.60, p ≤ 0.043, η2 = 0.17] intra−hemispherical connections in the contralateral hemisphere and occipito−motor [F(1, 22) = 7.33, p ≤ 0.013, η2 = 0.25] on the ipsilateral hemisphere to the injured leg. Higher functional connectivity in patients after ACLR, attained by increased emphasis of functional connections incorporating the somatosensory and visual areas, may serve as a compensatory mechanism to control postural stability of the injured leg in the early phase of rehabilitation. These preliminary results may help to develop new neurophysiological assessments for detecting functional deficiencies after ACLR in the future. AU - Lehmann, Tim AU - Büchel, Daniel AU - Mouton, Caroline AU - Gokeler, Alli AU - Seil, Romain AU - Baumeister, Jochen ID - 32434 JF - Frontiers in Human Neuroscience KW - Behavioral Neuroscience KW - Biological Psychiatry KW - Psychiatry and Mental health KW - Neurology KW - Neuropsychology and Physiological Psychology SN - 1662-5161 TI - Functional Cortical Connectivity Related to Postural Control in Patients Six Weeks After Anterior Cruciate Ligament Reconstruction VL - 15 ER - TY - JOUR AB - Abstract Mobile Electroencephalography (EEG) provides insights into cortical contributions to postural control. Although changes in theta (4–8 Hz) and alpha frequency power (8–12 Hz) were shown to reflect attentional and sensorimotor processing during balance tasks, information about the effect of stance leg on cortical processing related to postural control is lacking. Therefore, the aim was to examine patterns of cortical activity during single-leg stance with varying surface stability. EEG and force plate data from 21 healthy males (22.43 ± 2.23 years) was recorded during unipedal stance (left/right) on a stable and unstable surface. Using source-space analysis, power spectral density was analyzed in the theta, alpha-1 (8–10 Hz) and alpha-2 (10–12 Hz) frequency bands. Repeated measures ANOVA with the factors leg and surface stability revealed significant interaction effects in the left (p = 0.045, ηp2 = 0.13) and right motor clusters (F = 16.156; p = 0.001, ηp2 = 0.41). Furthermore, significant main effects for surface stability were observed for the fronto-central cluster (theta), left and right motor (alpha-1), as well as for the right parieto-occipital cluster (alpha-1/alpha-2). Leg dependent changes in alpha-2 power may indicate lateralized patterns of cortical processing in motor areas during single-leg stance. Future studies may therefore consider lateralized patterns of cortical activity for the interpretation of postural deficiencies in unilateral lower limb injuries. AU - Büchel, Daniel AU - Lehmann, Tim AU - Ullrich, Sarah AU - Cockcroft, John AU - Louw, Quinette AU - Baumeister, Jochen ID - 32435 IS - 4 JF - Experimental Brain Research KW - General Neuroscience SN - 0014-4819 TI - Stance leg and surface stability modulate cortical activity during human single leg stance VL - 239 ER - TY - JOUR AU - Büchel, Daniel AU - Lehmann, Tim AU - Sandbakk, Øyvind AU - Baumeister, Jochen ID - 35626 IS - 1 JF - Scientific Reports KW - Multidisciplinary SN - 2045-2322 TI - EEG‑derived brain graphs are reliable measures for exploring exercise‑induced changes in brain networks VL - 11 ER - TY - GEN AU - Neukötter, Moritz AU - Jesinghausen, Steffen AU - Schmid, Hans-Joachim ID - 24475 TI - Theoretische Beschreibung des Tropfenbildungsprozesses bei der Filament Extension Atomization: Entwicklung eines Vorhersagemodells für die Tropfengröße (Poster) ER - TY - GEN AU - Neukötter, Moritz AU - Jesinghausen, Steffen AU - Schmid, Hans-Joachim ID - 30221 TI - Filament Extension Atomization – A novel Process for Powder Production? (Presentation) ER - TY - JOUR AU - Möhring, Julia AU - Krumhöfner, Anika AU - Gräfin von Plettenberg, Elisabeth Gudila Sophia Ida Maria ID - 43016 JF - - TI - Bewegungsförderung in Ganztagsschulen ER - TY - GEN AU - Leineweber, Jonas ID - 33210 TI - Veranstaltungsbericht: Immaterielles Kulturerbe in Nordrhein-Westfalen – Steigerlied und Trinkhallenkultur im Ruhrgebiet erhalten Auszeichnung anlässlich der Neuaufnahmen in das nordrhein-westfälische Landesinventar ER - TY - GEN AU - Leineweber, Jonas ID - 33209 TI - Tagungsbericht: Immaterielles Kulturerbe und regionale Identität. Gesellschaftliche Repräsentation und Partizipation im Schützenwesen ER - TY - JOUR AB - Zinc oxide nanoparticles (ZnO NP) used for the channel region in inverted coplanar setup in Thin Film Transistors (TFT) were the focus of this study. The regions between the source electrode and the ZnO NP and the drain electrode were under investigation as they produce a Schottky barrier in metal-semiconductor interfaces. A more general Thermionic emission theory must be evaluated: one that considers both metal/semiconductor interfaces (MSM structures). Aluminum, gold, and nickel were used as metallization layers for source and drain electrodes. An organic-inorganic nanocomposite was used as a gate dielectric. The TFTs transfer and output characteristics curves were extracted, and a numerical computational program was used for fitting the data; hence information about Schottky Barrier Height (SBH) and ideality factors for each TFT could be estimated. The nickel metallization appears with the lowest SBH among the metals investigated. For this metal and for higher drain-to-source voltages, the SBH tended to converge to some value around 0.3 eV. The developed fitting method showed good fitting accuracy even when the metallization produced different SBH in each metal-semiconductor interface, as was the case for gold metallization. The Schottky effect is also present and was studied when the drain-to-source voltages and/or the gate voltage were increased. AU - Kaufmann, Ivan Rodrigo AU - Zerey, Onur AU - Meyers, Thorsten AU - Reker, Julia AU - Vidor, Fábio AU - Hilleringmann, Ulrich ID - 39383 IS - 5 JF - Nanomaterials KW - General Materials Science KW - General Chemical Engineering SN - 2079-4991 TI - A Study about Schottky Barrier Height and Ideality Factor in Thin Film Transistors with Metal/Zinc Oxide Nanoparticles Structures Aiming Flexible Electronics Application VL - 11 ER - TY - CONF AU - Reker, Julia AU - Meyers, Thorsten AU - Vidor, Fabio F. AU - Joubert, Trudi-Heleen AU - Hilleringmann, Ulrich ID - 39395 T2 - 2021 Smart Systems Integration (SSI) TI - Complementary Inverter Circuits on Flexible Substrates ER - TY - CONF AU - Hilleringmann, Ulrich AU - Petrov, Dmitry AU - Mwammenywa, Ibrahim AU - Kagarura, Geoffrey M. ID - 39381 T2 - 2021 IEEE AFRICON TI - Local Power Control using Wireless Sensor System for Microgrids in Africa ER - TY - CONF AU - Andrews, George AU - Hilleringmann, Ulrich AU - Joubert, Trudi-Heleen ID - 39385 T2 - 2021 IEEE AFRICON TI - The Viability of a Non-Flow Capacitive Biosensing Microsystem for Whole Cell Counting ER - TY - CONF AU - Andrews, George AU - Hilleringmann, Ulrich AU - Joubert, Trudi-Heleen ID - 39386 T2 - 2021 IEEE AFRICON TI - The Viability of a Non-Flow Capacitive Biosensing Microsystem for Whole Cell Counting ER - TY - CHAP AU - Gerhardts, Lara AU - Dehmel, Lukas AU - Meister, Dorothee M. ED - Wolf, Karsten D ED - Rummler, Klaus ED - Bettinger, Patrick ED - Aßmann, Sandra ID - 43143 T2 - Jahrbuch Medienpädagogik 16. Medienpädagogik in Zeiten einer tiefgreifenden Mediatisierung TI - Die berufliche Tabletaneignung von Lehrkräften als Beispiel der Mediatisierung pädagogischer Handlungskontexte. Theoretische Perspektiven und empirische Befunde ER - TY - CHAP AU - Dehmel, Lukas ED - Bernhard-Skala,, Christian ED - Bolten-Bühler, Ricarda ED - Koller, Julia ED - Rohs, Matthias ED - Wahl, Johannes ID - 43142 T2 - Erwachsenenpädagogische Digitalisierungsforschung. Impulse - Befunde - Perspektiven. Bielefeld TI - Zur Entgrenzung der Arbeit des medienpädagogischen Weiterbildungspersonals im Kontext tiefgreifender Mediatisierung ER - TY - JOUR AU - Hälterlein, Jens ID - 43278 IS - 1 JF - Big Data & Society TI - Epistemologies of predictive policing: Mathematical social science, social physics and machine learning VL - 8 ER - TY - JOUR AB - Let E be an ordinary elliptic curve over a finite field and g be a positive integer. Under some technical assumptions, we give an algorithm to span the isomorphism classes of principally polarized abelian varieties in the isogeny class of E⁹ . The varieties are first described as hermitian lattices over (not necessarily maximal) quadratic orders and then geometrically in terms of their algebraic theta null point. We also show how to algebraically compute Siegel modular forms of even weight given as polynomials in the theta constants by a careful choice of an affine lift of the theta null point. We then use these results to give an algebraic computation of Serre’s obstruction for principally polarized abelian threefolds isogenous to E³ and of the Igusa modular form in dimension 4. We illustrate our algorithms with examples of curves with many rational points over finite fields. AU - Kirschmer, Markus AU - Narbonne, Fabien AU - Ritzenthaler, Christophe AU - Robert, Damien ID - 34912 IS - 333 JF - Mathematics of Computation KW - Applied Mathematics KW - Computational Mathematics KW - Algebra and Number Theory SN - 0025-5718 TI - Spanning the isogeny class of a power of an elliptic curve VL - 91 ER - TY - GEN AU - Schroeter-Wittke, Harald ID - 41088 SN - 0540–6226 T2 - Jahrbuch für Evangelische Kirchengeschichte des Rheinlandes TI - Anette Baumann / Alexander Jendorff / Frank Theisen (Hgg.), Religion – Migration – Integration. Studien zu Wechselwirkungen religiös motivierter Mobilität im vormodernen Europa, Tübingen 2019 VL - 70 ER - TY - GEN AU - Schroeter-Wittke, Harald ID - 41090 SN - 0540–6226 T2 - Jahrbuch für Evangelische Kirchengeschichte des Rheinlandes TI - Hendrik Meyer-Magister, Wehrdienst und Verweigerung als komplementäres Handeln. Individualisierungsprozesse im bundesdeutschen Protestantismus der 1950er Jahre (RBRD 7), Tübingen 2019 VL - 70 ER - TY - GEN AU - Schroeter-Wittke, Harald ID - 41091 SN - 0540–6226 T2 - Jahrbuch für Evangelische Kirchengeschichte des Rheinlandes TI - Jutta Stander-Dulisch, Glaubenskrisen, Neue Religionen und der Papst. Religion in „Stern“ und Spiegel“ von 1960 bis 2014, Bielefeld 2019 VL - 70 ER - TY - JOUR AB - The relativistic wave equations determine the dynamics of quantum fields in the context of quantum field theory. One of the conventional tools for dealing with the relativistic bound state problem is the Klein-Fock-Gordon equation. In this work, using a developed scheme, we present how to surmount the centrifugal part and solve the modified Klein-Fock-Gordon equation for the linear combination of Hulthén and Yukawa potentials. In particular, we show that the relativistic energy eigenvalues and corresponding radial wave functions are obtained from supersymmetric quantum mechanics by applying the shape invariance concept. Here, both scalar potential conditions, which are whether equal and nonequal to vector potential, are considered in the calculation. The energy levels and corresponding normalized eigenfunctions are represented as a recursion relation regarding the Jacobi polynomials for arbitrary l states. Beyond that, a closed form of the normalization constant of the wave functions is found. Furthermore, we state that the energy eigenvalues are quite sensitive with potential parameters for the quantum states. The nonrelativistic and relativistic results obtained within SUSY QM overlap entirely with the results obtained by ordinary quantum mechanics, and it displays that the mathematical implementation of SUSY quantum mechanics is quite perfect. AU - Ahmadov, A. I. AU - Aslanova, S. M. AU - Orujova, M. Sh. AU - Badalov, S. V. ED - Vagnozzi, Sunny ID - 44042 JF - Advances in High Energy Physics KW - Nuclear and High Energy Physics SN - 1687-7365 TI - Analytical Bound State Solutions of the Klein-Fock-Gordon Equation for the Sum of Hulthén and Yukawa Potential within SUSY Quantum Mechanics VL - 2021 ER - TY - CONF AU - Meydani, Elnaz AU - Düsing, Christoph AU - Trier, Matthias ID - 44073 T2 - Innovation Through Information Systems: Volume II: A Collection of Latest Research on Technology Issues TI - Towards a Trust-Aware Item Recommendation System on a Graph Autoencoder with Attention Mechanism ER - TY - JOUR AU - Neufeld, Sergej AU - Bocchini, Adriana AU - Schmidt, Wolf Gero ID - 22310 JF - Physical Review Materials SN - 2475-9953 TI - Potassium titanyl phosphate Z- and Y-cut surfaces from density-functional theory ER - TY - JOUR AU - Plaickner, Julian AU - Speiser, Eugen AU - Braun, Christian AU - Schmidt, Wolf Gero AU - Esser, Norbert AU - Sanna, Simone ID - 22008 JF - Physical Review B SN - 2469-9950 TI - Surface localized phonon modes at the Si(553)-Au nanowire system ER - TY - JOUR AU - Meier, Lukas AU - Schmidt, Wolf Gero ID - 40244 IS - 1 JF - physica status solidi (b) KW - Condensed Matter Physics KW - Electronic KW - Optical and Magnetic Materials SN - 0370-1972 TI - GaInP/AlInP(001) Interfaces from Density Functional Theory VL - 259 ER - TY - JOUR AU - Ruiz Alvarado, Isaac Azahel AU - Karmo, Marsel AU - Runge, Erich AU - Schmidt, Wolf Gero ID - 22009 JF - ACS Omega SN - 2470-1343 TI - InP and AlInP(001)(2 × 4) Surface Oxidation from Density Functional Theory ER - TY - JOUR AB - We perform a theoretical analysis of the structural and electronic properties of sodium potassium niobate K1-xNaxNbO3 in the orthorhombic room-temperature phase, based on density-functional theory in combination with the supercell approach. Our results for x=0 and x=0.5 are in very good agreement with experimental measurements and establish that the lattice parameters decrease linearly with increasing Na contents, disproving earlier theoretical studies based on the virtual-crystal approximation that claimed a highly nonlinear behavior with a significant structural distortion and volume reduction in K0.5Na0.5NbO3 compared to both end members of the solid solution. Furthermore, we find that the electronic band gap varies very little between x=0 and x=0.5, reflecting the small changes in the lattice parameters. AU - Bidaraguppe Ramesh, Nithin AU - Schmidt, Falko AU - Schindlmayr, Arno ID - 22960 IS - 8 JF - The European Physical Journal B SN - 1434-6028 TI - Lattice parameters and electronic band gap of orthorhombic potassium sodium niobate K0.5Na0.5NbO3 from density-functional theory VL - 94 ER - TY - JOUR AU - Friedrich, Christoph AU - Blügel, Stefan AU - Schindlmayr, Arno ID - 22761 IS - 3 JF - Physical Review B SN - 2469-9950 TI - Erratum: Efficient implementation of the GW approximation within the all-electron FLAPW method [Phys. Rev. B 81, 125102 (2010)] VL - 104 ER - TY - JOUR AB - Uniaxial anisotropy in nonlinear birefringent crystals limits the efficiency of nonlinear optical interactions and breaks the spatial symmetry of light generated in the parametric down-conversion (PDC) process. Therefore, this effect is usually undesirable and must be compensated for. However, high gain may be used to overcome the destructive role of anisotropy in order to generate bright two-mode correlated twin-beams. In this work, we provide a rigorous theoretical description of the spatial properties of bright squeezed light in the presence of strong anisotropy. We investigate a single crystal and a system of two crystals with an air gap (corresponding to a nonlinear SU(1,1) interferometer) and demonstrate the generation of bright correlated twin-beams in such configurations at high gain due to anisotropy. We explore the mode structure of the generated light and show how anisotropy, together with crystal spacing, can be used for radiation shaping. AU - Riabinin, M. AU - Sharapova, Polina AU - Meier, Torsten ID - 37334 IS - 14 JF - Optics Express KW - Atomic and Molecular Physics KW - and Optics SN - 1094-4087 TI - Bright correlated twin-beam generation and radiation shaping in high-gain parametric down-conversion with anisotropy VL - 29 ER - TY - JOUR AU - Geraldi, Andrea AU - De, Syamsundar AU - Laneve, Alessandro AU - Barkhofen, Sonja AU - Sperling, Jan AU - Mataloni, Paolo AU - Silberhorn, Christine ID - 26287 JF - Physical Review Research SN - 2643-1564 TI - Transient subdiffusion via disordered quantum walks ER - TY - JOUR AU - Tiedau, J. AU - Engelkemeier, M. AU - Brecht, Benjamin AU - Sperling, Jan AU - Silberhorn, Christine ID - 21021 JF - Physical Review Letters SN - 0031-9007 TI - Statistical Benchmarking of Scalable Photonic Quantum Systems VL - 126 ER - TY - JOUR AU - Prasannan, Nidhin AU - De, Syamsundar AU - Barkhofen, Sonja AU - Brecht, Benjamin AU - Silberhorn, Christine AU - Sperling, Jan ID - 26286 JF - Physical Review A SN - 2469-9926 TI - Experimental entanglement characterization of two-rebit states VL - 103 ER - TY - JOUR AU - Köhnke, S. AU - Agudelo, E. AU - Schünemann, M. AU - Schlettwein, O. AU - Vogel, W. AU - Sperling, Jan AU - Hage, B. ID - 26285 JF - Physical Review Letters SN - 0031-9007 TI - Quantum Correlations beyond Entanglement and Discord ER - TY - JOUR AB - Employing the ultrafast control of electronic states of a semiconductor quantum dot in a cavity, we introduce an approach to achieve on-demand emission of single photons with almost perfect indistinguishability and photon pairs with near ideal entanglement. Our scheme is based on optical excitation off resonant to a cavity mode followed by ultrafast control of the electronic states using the time-dependent quantum-confined Stark effect, which then allows for cavity-resonant emission. Our theoretical analysis considers cavity-loss mechanisms, the Stark effect, and phonon-induced dephasing, allowing realistic predictions for finite temperatures. AU - Bauch, David AU - Heinze, Dirk Florian AU - Förstner, Jens AU - Jöns, Klaus AU - Schumacher, Stefan ID - 23816 JF - Physical Review B KW - tet_topic_qd SN - 2469-9950 TI - Ultrafast electric control of cavity mediated single-photon and photon-pair generation with semiconductor quantum dots VL - 104 ER - TY - JOUR AB - AbstractA detailed investigation of the energy levels of perylene-3,4,9,10-tetracarboxylic tetraethylester as a representative compound for the whole family of perylene esters was performed. It was revealed via electrochemical measurements that one oxidation and two reductions take place. The bandgaps determined via the electrochemical approach are in good agreement with the optical bandgap obtained from the absorption spectra via a Tauc plot. In addition, absorption spectra in dependence of the electrochemical potential were the basis for extensive quantum-chemical calculations of the neutral, monoanionic, and dianionic molecules. For this purpose, calculations based on density functional theory were compared with post-Hartree–Fock methods and the CAM-B3LYP functional proved to be the most reliable choice for the calculation of absorption spectra. Furthermore, spectral features found experimentally could be reproduced with vibronic calculations and allowed to understand their origins. In particular, the two lowest energy absorption bands of the anion are not caused by absorption of two distinct electronic states, which might have been expected from vertical excitation calculations, but both states exhibit a strong vibronic progression resulting in contributions to both bands. AU - Wiebeler, Christian AU - Vollbrecht, Joachim AU - Neuba, Adam AU - Kitzerow, Heinz-Siegfried AU - Schumacher, Stefan ID - 39653 IS - 1 JF - Scientific Reports KW - Multidisciplinary SN - 2045-2322 TI - Unraveling the electrochemical and spectroscopic properties of neutral and negatively charged perylene tetraethylesters VL - 11 ER - TY - JOUR AU - Klement, Philip AU - Dehnhardt, Natalie AU - Dong, Chuan-Ding AU - Dobener, Florian AU - Bayliff, Samuel AU - Winkler, Julius AU - Hofmann, Detlev M. AU - Klar, Peter J. AU - Schumacher, Stefan AU - Chatterjee, Sangam AU - Heine, Johanna ID - 40434 IS - 23 JF - Advanced Materials KW - Mechanical Engineering KW - Mechanics of Materials KW - General Materials Science SN - 0935-9648 TI - Atomically Thin Sheets of Lead‐Free 1D Hybrid Perovskites Feature Tunable White‐Light Emission from Self‐Trapped Excitons VL - 33 ER - TY - JOUR AU - Barkhausen, Franziska AU - Pukrop, Matthias AU - Schumacher, Stefan AU - Ma, Xuekai ID - 21359 IS - 7 JF - Physical Review B SN - 2469-9950 TI - Structuring coflowing and counterflowing currents of polariton condensates in concentric ring-shaped and elliptical potentials VL - 103 ER - TY - JOUR AU - Franz, Martin AU - Chandola, Sandhya AU - Koy, Maximilian AU - Zielinski, Robert AU - Aldahhak, Hazem AU - Das, Mowpriya AU - Freitag, Matthias AU - Gerstmann, Uwe AU - Liebig, Denise AU - Hoffmann, Adrian Karl AU - Rosin, Maximilian AU - Schmidt, Wolf Gero AU - Hogan, Conor AU - Glorius, Frank AU - Esser, Norbert AU - Dähne, Mario ID - 24975 JF - Nature Chemistry SN - 1755-4330 TI - Controlled growth of ordered monolayers of N-heterocyclic carbenes on silicon ER - TY - JOUR AB - Density-functional theory within a Berry-phase formulation of the dynamical polarization is used to determine the second-order susceptibility χ(2) of lithium niobate (LiNbO3). Defect trapped polarons and bipolarons are found to strongly enhance the nonlinear susceptibility of the material, in particular if localized at NbV–VLi defect pairs. This is essentially a consequence of the polaronic excitation resulting in relaxation-induced gap states. The occupation of these levels leads to strongly enhanced χ(2) coefficients and allows for the spatial and transient modification of the second-harmonic generation of macroscopic samples. AU - Kozub, Agnieszka L. AU - Schindlmayr, Arno AU - Gerstmann, Uwe AU - Schmidt, Wolf Gero ID - 23418 JF - Physical Review B SN - 2469-9950 TI - Polaronic enhancement of second-harmonic generation in lithium niobate VL - 104 ER - TY - CONF AU - Rose, Hendrik AU - Paul, Jagannath AU - Wahlstrand, Jared K. AU - Bristow, Alan D. AU - Meier, Torsten ED - Betz, Markus ED - Elezzabi, Abdulhakem Y. ID - 23475 T2 - Ultrafast Phenomena and Nanophotonics XXV TI - Theoretical analysis and simulations of two-dimensional Fourier transform spectroscopy performed on exciton-polaritons of a quantum-well microcavity system VL - 11684 ER - TY - JOUR AU - Krauss-Kodytek, L. AU - Hannes, W.-R. AU - Meier, Torsten AU - Ruppert, C. AU - Betz, M. ID - 37333 IS - 8 JF - Physical Review B SN - 2469-9950 TI - Nondegenerate two-photon absorption in ZnSe: Experiment and theory VL - 104 ER - TY - JOUR AU - Riabinin, Matvei AU - Sharapova, Polina AU - Bartley, Tim AU - Meier, Torsten ID - 21547 IS - 4 JF - Journal of Physics Communications SN - 2399-6528 TI - Generating two-mode squeezing with multimode measurement-induced nonlinearity VL - 5 ER - TY - JOUR AU - Krauss-Kodytek, L. AU - Hannes, Wolf-Rüdiger AU - Meier, Torsten AU - Ruppert, C. AU - Betz, M. ID - 23472 IS - 8 JF - Physical Review B SN - 2469-9950 TI - Nondegenerate two-photon absorption in ZnSe: Experiment and theory VL - 104 ER -