2,266 results on '"Redinger AS"'
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2. Stabilization of highly efficient perovskite solar cells with a tailored supramolecular interface
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Chenxu Zhao, Zhiwen Zhou, Masaud Almalki, Michael A. Hope, Jiashang Zhao, Thibaut Gallet, Anurag Krishna, Aditya Mishra, Felix T. Eickemeyer, Jia Xu, Yingguo Yang, Shaik M. Zakeeruddin, Alex Redinger, Tom J. Savenije, Lyndon Emsley, Jianxi Yao, Hong Zhang, and Michael Grätzel
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Science - Abstract
Abstract The presence of defects at the interface between the perovskite film and the carrier transport layer poses significant challenges to the performance and stability of perovskite solar cells (PSCs). Addressing this issue, we introduce a dual host-guest (DHG) complexation strategy to modulate both the bulk and interfacial properties of FAPbI3-rich PSCs. Through NMR spectroscopy, a synergistic effect of the dual treatment is observed. Additionally, electro-optical characterizations demonstrate that the DHG strategy not only passivates defects but also enhances carrier extraction and transport. Remarkably, employing the DHG strategy yields PSCs with power conversion efficiencies (PCE) of 25.89% (certified at 25.53%). Furthermore, these DHG-modified PSCs exhibit enhanced operational stability, retaining over 96.6% of their initial PCE of 25.55% after 1050 hours of continuous operation under one-sun illumination, which was the highest initial value in the recently reported articles. This work establishes a promising pathway for stabilizing high-efficiency perovskite photovoltaics through supramolecular engineering, marking a significant advancement in the field.
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- 2024
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3. Stabilization of highly efficient perovskite solar cells with a tailored supramolecular interface
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Zhao, Chenxu, Zhou, Zhiwen, Almalki, Masaud, Hope, Michael A., Zhao, Jiashang, Gallet, Thibaut, Krishna, Anurag, Mishra, Aditya, Eickemeyer, Felix T., Xu, Jia, Yang, Yingguo, Zakeeruddin, Shaik M., Redinger, Alex, Savenije, Tom J., Emsley, Lyndon, Yao, Jianxi, Zhang, Hong, and Grätzel, Michael
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- 2024
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4. Mammal declines correspond with increasing prevalence of Burmese pythons at their southern invasion front in the Florida Keys
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Redinger, Joseph, Lord, Isaac, Dixon, Jeremy, and Cove, Michael V.
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- 2024
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5. How much gallium do we need for a p-type Cu(In,Ga)Se2?
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Ramírez, Omar, Lanzoni, Evandro Martin, Poeira, Ricardo G., Weiss, Thomas P., Leturcq, Renaud, Redinger, Alex, and Siebentritt, Susanne
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Condensed Matter - Materials Science ,Physics - Applied Physics - Abstract
Doping in the chalcopyrite Cu(In,Ga)Se2 is determined by intrinsic point defects. In the ternary CuInSe2, both N-type and P-type conductivity can be obtained depending on the growth conditions and stoichiometry: N-type is obtained when grown Cu-poor, Se-poor and alkali-free. CuGaSe2, on the other hand, is found to be always a P-type semiconductor that seems to resist all kinds of N-type doping no matter whether it comes from native defects or extrinsic impurities. In this contribution, we study the N-to-P transition in Cu-poor Cu(In,Ga)Se2 single crystals in dependence of the gallium content. Our results show that Cu(In,Ga)Se2 can still be grown as an N-type semiconductor until the gallium content reaches the critical concentration of 15-19%, where the N-to-P transition occurs. Furthermore, trends in the Seebeck coefficient and activation energies extracted from temperature-dependent conductivity measurements, demonstrate that the carrier concentration drops by around two orders of magnitude near the transition concentration. Our proposed model explains the N-to-P transition based on the differences in formation energies of donor and acceptor defects caused by the addition of gallium.
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- 2022
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6. Cirrhosis and the surgical patient
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Grossniklaus, Emily J., Redinger, Jeffrey W., and Johnson, Kay M.
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- 2024
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7. The Great Lakes’ most unwanted: Characterizing the impacts of the top ten Great Lakes aquatic invasive species
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Lower, El, Sturtevant, Rochelle, Iott, Susannah, Martinez, Felix, Rutherford, Ed, Mason, Doran M., Redinger, Joseph, and Elgin, Ashley K.
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- 2024
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8. Human monoclonal antibodies inhibit invasion of transgenic Plasmodium knowlesi expressing Plasmodium vivax Duffy binding protein
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Quentin D. Watson, Lenore L. Carias, Alyssa Malachin, Karli R. Redinger, Jürgen Bosch, Martino Bardelli, Lea Baldor, Lionel Brice Feufack-Donfack, Jean Popovici, Robert W. Moon, Simon J. Draper, Peter A. Zimmerman, and Christopher L. King
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A monoclonal antibody ,Plasmodium vivax ,Plasmodium knowlesi ,Duffy binding protein ,Duffy antigen ,Arctic medicine. Tropical medicine ,RC955-962 ,Infectious and parasitic diseases ,RC109-216 - Abstract
Abstract Background Plasmodium vivax has been more resistant to various control measures than Plasmodium falciparum malaria because of its greater transmissibility and ability to produce latent parasite forms. Therefore, developing P. vivax vaccines and therapeutic monoclonal antibodies (humAbs) remains a high priority. The Duffy antigen receptor for chemokines (DARC) expressed on erythrocytes is central to P. vivax invasion of reticulocytes. P. vivax expresses a Duffy binding protein (PvDBP) on merozoites, a DARC ligand, and the DARC: PvDBP interaction is critical for P. vivax blood stage malaria. Therefore, PvDBP is a leading vaccine candidate for P. vivax and a target for therapeutic human monoclonal antibodies (humAbs). Methods Here, the functional activity of humAbs derived from naturally exposed and vaccinated individuals are compared for the first time using easily cultured Plasmodium knowlesi (P. knowlesi) that had been genetically modified to replace its endogenous PkDBP orthologue with PvDBP to create a transgenic parasite, PkPvDBPOR. This transgenic parasite requires DARC to invade human erythrocytes but is not reticulocyte restricted. This model was used to evaluate the invasion inhibition potential of 12 humAbs (9 naturally acquired; 3 vaccine-induced) targeting PvDBP individually and in combinations using growth inhibition assays (GIAs). Results The PvDBP-specific humAbs demonstrated 70–100% inhibition of PkPvDBPOR invasion with the IC50 values ranging from 51 to 338 µg/mL for the 9 naturally acquired (NA) humAbs and 33 to 99 µg/ml for the 3 vaccine-induced (VI) humAbs. To evaluate antagonistic, additive, or synergistic effects, six pairwise combinations were performed using select humAbs. Of these combinations tested, one NA/NA (099100/094083) combination demonstrated relatively strong additive inhibition between 10 and 100 µg/mL; all combinations of NA and VI humAbs showed additive inhibition at concentrations below 25 µg/mL and antagonism at higher concentrations. None of the humAb combinations showed synergy. Invasion inhibition efficacy by some mAbs shown with PkPvDBPOR was closely replicated using P. vivax clinical isolates. Conclusion The PkPvDBPOR transgenic model is a robust surrogate of P. vivax to assess invasion and growth inhibition of human monoclonal Abs recognizing PvDBP individually and in combination. There was no synergistic interaction for growth inhibition with the humAbs tested here that target different epitopes or subdomains of PvDBP, suggesting little benefit in clinical trials using combinations of these humAbs.
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- 2023
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9. Carrier concentration resolved
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Redinger, Alex
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- 2024
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10. Perioperative Liver and Kidney Diseases
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Redinger, Jeffrey W., Johnson, Kay M., and Slawski, Barbara A.
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- 2024
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11. An improved method to assess the encapsulation response in arthropods
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Kirschman, Lucas J., Eastman, Hannah M., Irovic, Frank J., Nix, Nathaniel A., Bui, Ly Tuan Kiet, Blackmon, Sydney L., Greenlee, Jaylen S., Lamichhane, Rubina, Mabuce, Jack D., McAllister, Hannah K., Nevill, Lilly F., Redinger, Peyton, Rivers, Nia I., and Sprague, Jackson L.
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- 2024
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12. Human monoclonal antibodies inhibit invasion of transgenic Plasmodium knowlesi expressing Plasmodium vivax Duffy binding protein
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Watson, Quentin D., Carias, Lenore L., Malachin, Alyssa, Redinger, Karli R., Bosch, Jürgen, Bardelli, Martino, Baldor, Lea, Feufack-Donfack, Lionel Brice, Popovici, Jean, Moon, Robert W., Draper, Simon J., Zimmerman, Peter A., and King, Christopher L.
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- 2023
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13. What internal medicine attendings talk about at morning report: a multicenter study
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Redinger, Jeffrey W., Heppe, Daniel B., Albert, Tyler J., Cornia, Paul B., Gordon, Kirsha S., Arundel, Cherinne, Bradley, Joel M., Caputo, Laura M., Chun, Jonathan W., Cyr, Jessica E., Ehlers, Erik T., Guidry, Michelle M., Jagannath, Anand D., Kwan, Brian K., Laudate, James D., Mitchell, Christine A., Smeraglio, Andrea C., Sweigart, Joseph R., Tuck, Matthew G., and Gunderson, Craig G.
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- 2023
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14. Modification of mono-layer MoS2 through post-deposition treatment and oxidation for enhanced optoelectronic properties
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Jonathan Rommelfangen, Marco A. Gonzalez-Angulo, Devendra Pareek, Levent Gütay, Phillip J. Dale, and Alex Redinger
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Biotechnology ,TP248.13-248.65 ,Physics ,QC1-999 - Abstract
Precise control of the optical and electrical properties of mono-layer (ML) thin MoS2 is crucial for future applications in functional devices. Depending on the synthesis route and the post-deposition annealing protocols, the number of sulfur vacancies in the material is different, which has a profound impact on the properties of the 2D layer. Here, we show that the sulfur vacancy-rich ML MoS2 films oxidize already at room temperature, which changes the photoluminescence (PL) yield, the MoS2–Al2O3 substrate interaction, and the structural integrity of the films. We used x-ray photoelectron spectroscopy to monitor the formation of MoO3 and possibly MoS3−xOx after exposure to air and to quantify the number of sulfur defects in the films. Atomic force microscopy measurements allow us to pinpoint the exact regions of oxidation and develop a dedicated low temperature heating procedure to remove oxidized species, leading to MoO3-free MoS2 films. AFM and Kelvin probe force microscopy show that the MoS2–Al2O3 substrate coupling is changed. The reduction in the MoS2–substrate coupling, combined with a preferential oxidation of sulfur vacancies, leads to a sevenfold increase in the PL intensity, and the ratio between trions and neutral excitons is changed. Our work highlights the importance of oxidized sulfur vacancies and provides useful methods to measure and manipulate their number in MoS2. Furthermore, changes in the MoS2–substrate interaction via sulfur vacancies and oxidation offer an elegant pathway to tune the optoelectronic properties of the two-dimensional films.
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- 2024
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15. Quantifying recombination and charge carrier extraction in halide perovskites via hyperspectral time-resolved photoluminescence imaging
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H. Phirke, S. Gharabeiki, A. Singh, A. Krishna, S. Siebentritt, and A. Redinger
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Energy conservation ,TJ163.26-163.5 ,Renewable energy sources ,TJ807-830 - Abstract
Identifying sources of nonradiative recombination and quantifying charge carrier extraction in halide perovskite solar cells are important in further developing this thin-film technology. Steady-state and time-resolved photoluminescence (TRPL), in combination with analytical modeling, have emerged as non-destructive tools to achieve the desired results. However, the exact location of the recombination and charge carrier extraction losses in devices is often obscured by various competing processes when photoluminescence measurements are analyzed. Here, we show via absolute-photon-calibrated hyperspectral photoluminescence and TRPL imaging how surface passivation and inhomogeneities at interfaces impact the photoluminescence quantum yields and minority carrier lifetimes. Laser illumination from the perovskite and glass/TiO2 sides allows us to disentangle changes in surface recombination velocity from the charge carrier extraction at the electron transport layer. We find that charge extraction is spatially modulated due to an inhomogeneous mesoporous (mp)-TiO2 film thickness. Our results show that the mp-TiO2 layer is not fully optimized since the electronic properties are spatially modified, leading to lateral changes in quasi-Fermi-level splitting, minority carrier lifetime and, consequently, a reduction in open-circuit voltage.
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- 2024
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16. First principles studies of the electronic and structural properties of the rutile VO$_{2}$(110) surface and its oxygen-rich terminations
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Planer, Jakub, Mittendorfer, Florian, and Redinger, Josef
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Condensed Matter - Materials Science - Abstract
We present a Density Functional Theory (DFT) study of the structural and electronic properties of bare rutile VO$_{2}$(110) surfaces and its oxygen-rich terminations. We discuss the performance of various DFT functionals, including PBE, PBE+U (U = 2 eV), SCAN and SCAN+rVV functionals with non-magnetic and ferromagnetic spin ordering. We predict the presence of a ring-like termination that is electronically and structurally related to a V$_{2}$O$_{5}$(001) monolayer and shows a higher stability than pure oxygen adsorption phases. Despite the fact that the calculated phase stabilities depend on the chosen functional, our results show that employing the spin-polarized SCAN functional offers a good compromise yielding both a reasonable description of the structural and electronic properties of the rutile VO$_{2}$ bulk phase and the enthalpy of formation for different stages of vanadium oxidation.
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- 2021
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17. An oxygen-rich, tetrahedral surface phase on high-temperature rutile VO$_2$(110)$_\text{T}$ single crystals
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Wagner, Margareta, Planer, Jakub, Heller, Bettina S. J., Langer, Jens, Limbeck, Andreas, Boatner, Lynn A., Steinrück, Hans-Peter, Redinger, Josef, Maier, Florian, Mittendorfer, Florian, Schmid, Michael, and Diebold, Ulrike
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Condensed Matter - Materials Science - Abstract
Vanadium dioxide undergoes a metal-insulator transition (MIT) from an insulating (monoclinic) to a metallic (tetragonal) phase close to room temperature, which makes it a promising functional material for many applications, e.g. as chemical sensors. Not much is known about its surface and interface properties, although these are critical in many of its applications. This work presents an atomic-scale investigation of the tetragonal rutile VO$_2$(110)$_\text{T}$ single-crystal surface and reports results obtained with scanning tunneling microscopy (STM), low-energy electron diffraction (LEED) and X-ray photoelectron spectroscopy (XPS), supported by density-functional theory-based (DFT) calculations. The surface reconstructs into an oxygen-rich (2$\times$2) superstructure that coexists with small patches of the underlying, unreconstructed (110)-(1$\times$1) surface. The best structural model for the (2$\times$2) surface termination, conceptually derived from a vanadium pentoxide (001) monolayer, consists of rings of corner-shared tetrahedra. Over a wide range of oxygen chemical potentials this reconstruction is more stable than the unreconstructed (110) surface as well as models proposed in the literature.
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- 2021
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18. The impact of Kelvin probe force microscopy operation modes and environment on grain boundary band bending in perovskite and Cu(In,Ga)Se2 solar cells
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Lanzoni, Evandro Martin, Gallet, Thibaut, Spindler, Conrad, Ramirez, Omar, Boumenou, Christian Kameni, Siebentritt, Susanne, and Redinger, Alex
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Condensed Matter - Materials Science - Abstract
An in-depth understanding of the electronic properties of grain boundaries (GB) in polycrystalline semiconductor absorbers is of high importance since their charge carrier recombination rates may be very high and hence limit the solar cell device performance. Kelvin Probe Force Microscopy (KPFM) is the method of choice to investigate GB band bending on the nanometer scale and thereby helps to develop passivation strategies. Here, it is shown that amplitude modulation AM-KPFM, which is by far the most common KPFM measurement mode, is not suitable to measure workfunction variations at GBs on rough samples, such as Cu(In,Ga)Se2 and CH3NH3PbI3. This is a direct consequence of a change in the cantilever-sample distance that varies on rough samples. Furthermore, we critically discuss the impact of different environments (air versus vacuum) and show that air exposure alters the GB and facet contrast, which leads to erroneous interpretations of the GB physics. Frequency modulation FM-KPFM measurements on non-air-exposed CIGSe and perovskite absorbers show that the amount of band bending measured at the GB is negligible and that the electronic landscape of the semiconductor surface is dominated by facet-related contrast due to the polycrystalline nature of the absorbers.
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- 2021
19. Tauchen und Herz-Kreislauf-Erkrankungen
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Heger, Maria, Kaiblinger, Josef, Preiml, Ulrike, Redinger, Christian, and Niebauer, Josef, editor
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- 2023
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20. Electronic and compositional properties of the rear‐side of stoichiometric CuInSe2 absorbers
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Boumenou, Christian Kameni, Elizabeth, Amala, Babbe, Finn, Debot, Alice, Mönig, Harry, and Redinger, Alex
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CuInSe2 ,Kelvin probe force microscopy ,scanning tunneling microscopy ,Condensed Matter Physics ,Electrical and Electronic Engineering ,Materials Engineering ,Applied Physics - Abstract
In-depth understanding and subsequent optimization of the contact layers in thin film solar cells are of high importance in order to reduce the amount of nonradiative recombination and thereby improve device performance. In this work, the buried MoSe2/CuInSe2 interface of stoichiometric absorbers is investigated with scanning tunneling spectroscopy and Kelvin probe force microscopy combined with compositional measurements acquired via photo-electron spectroscopy after a mechanical lift-off process. We find that the local density of states, as measured with scanning tunneling spectroscopy, is similar to the front-side of ultra-high vacuum annealed CISe absorbers. The grain boundaries exhibit a weak upward band bending, opposite to Cu-poor CuGaSe2, and we measure an increased Cu accumulation at the rear CISe surface compared to the bulk composition and a non-zero concentration of Cu on the Mo-side. Grazing incidence X-ray diffraction measurements corroborate that a small amount of a CuxSe secondary phase is present at the MoSe2/CuInSe2 interface in contrast to reports on Cu-poor material. Our findings shed new light into the complex interface formation of CuInSe2-based thin film solar cells grown under Cu-rich conditions.
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- 2021
21. Electronic and compositional properties of the rear-side of stoichiometric CuInSe2 absorbers
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Kameni Boumenou, C, Elizabeth, A, Babbe, F, Debot, A, Mönig, H, and Redinger, A
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CuInSe2 ,Kelvin probe force microscopy ,scanning tunneling microscopy ,Condensed Matter Physics ,Electrical and Electronic Engineering ,Materials Engineering ,Applied Physics - Abstract
In-depth understanding and subsequent optimization of the contact layers in thin film solar cells are of high importance in order to reduce the amount of nonradiative recombination and thereby improve device performance. In this work, the buried MoSe2/CuInSe2 interface of stoichiometric absorbers is investigated with scanning tunneling spectroscopy and Kelvin probe force microscopy combined with compositional measurements acquired via photo-electron spectroscopy after a mechanical lift-off process. We find that the local density of states, as measured with scanning tunneling spectroscopy, is similar to the front-side of ultra-high vacuum annealed CISe absorbers. The grain boundaries exhibit a weak upward band bending, opposite to Cu-poor CuGaSe2, and we measure an increased Cu accumulation at the rear CISe surface compared to the bulk composition and a non-zero concentration of Cu on the Mo-side. Grazing incidence X-ray diffraction measurements corroborate that a small amount of a CuxSe secondary phase is present at the MoSe2/CuInSe2 interface in contrast to reports on Cu-poor material. Our findings shed new light into the complex interface formation of CuInSe2-based thin film solar cells grown under Cu-rich conditions.
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- 2021
22. Telescoping prey selection in invasive Burmese pythons spells trouble for endangered rodents
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Lord, Isaac, Redinger, Joseph, Dixon, Jeremy, Hart, Kristen M., Guzy, Jacquelyn, Romagosa, Christina M., and Cove, Michael V.
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- 2023
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23. What internal medicine attendings talk about at morning report: a multicenter study
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Jeffrey W. Redinger, Daniel B. Heppe, Tyler J. Albert, Paul B. Cornia, Kirsha S. Gordon, Cherinne Arundel, Joel M. Bradley, Laura M. Caputo, Jonathan W. Chun, Jessica E. Cyr, Erik T. Ehlers, Michelle M. Guidry, Anand D. Jagannath, Brian K. Kwan, James D. Laudate, Christine A. Mitchell, Andrea C. Smeraglio, Joseph R. Sweigart, Matthew G. Tuck, and Craig G. Gunderson
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Medical education ,Graduate medical education ,Morning report ,Internal medicine residency ,Special aspects of education ,LC8-6691 ,Medicine - Abstract
Abstract Background Morning report is a core educational activity in internal medicine resident education. Attending physicians regularly participate in morning report and influence the learning environment, though no previous study has described the contribution of attending physicians to this conference. This study aims to describe attending comments at internal medicine morning reports. Methods We conducted a prospective, observational study of morning reports conducted at 13 internal medicine residency programs between September 1, 2020, and March 30, 2021. Each attending comment was described including its duration, whether the comment was teaching or non-teaching, teaching topic, and field of practice of the commenter. We also recorded morning report-related variables including number of learners, report format, program director participation, and whether report was scripted (facilitator has advance knowledge of the case). A regression model was developed to describe variables associated with the number of attending comments per report. Results There were 2,344 attending comments during 250 conferences. The median number of attendings present was 3 (IQR, 2–5). The number of comments per report ranged across different sites from 3.9 to 16.8 with a mean of 9.4 comments/report (SD, 7.4). 66% of comments were shorter than one minute in duration and 73% were categorized as teaching by observers. The most common subjects of teaching comments were differential diagnosis, management, and testing. Report duration, number of general internists, unscripted reports, and in-person format were associated with significantly increased number of attending comments. Conclusions Attending comments in morning report were generally brief, focused on clinical teaching, and covered a wide range of topics. There were substantial differences between programs in terms of the number of comments and their duration which likely affects the local learning environment. Morning report stakeholders that are interested in increasing attending involvement in morning report should consider employing in-person and unscripted reports. Additional studies are needed to explore best practice models of attending participation in morning report.
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- 2023
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24. New Developments in Psychiatric Boarding in Emergency Departments
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Redinger, Michael J., primary, Gibb, Tyler S., additional, and Redinger, Kathryn E., additional
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- 2024
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25. Virtual Emergency Medicine Clerkship Curriculum during the COVID-19 Pandemic: Development, Application, and Outcomes
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Redinger, Kathryn E. and Greene, Jeffrey D.
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Emergency Medicine ,Clerkship ,Curriculum ,Distance Learning ,COVID-19 - Abstract
The COVID-19 pandemic has been a significant catalyst for change in medical education and clinical care. The traditional model of bedside clinical teaching in required advanced clerkships was upended on March 17, 2020, when the Association of American Medical Colleges recommended removing medical students from direct patient care to prevent further spread of the disease and also to help conserve scarce personal protective equipment (PPE). This created unique challenges for delivering a robust, advanced emergency medicine (EM) clerkship since the emergency department is ground zero for the undifferentiated and potentially infected patient and has high demand for PPE. Here, we describe the development, application, and program evaluation of an online-based, virtual advanced EM curriculum developed rapidly in response to the COVID-19 pandemic. Starting March 23, 2020, we began rotating fourth-year medical students through a four-week rotation. We completed a total of four virtual clerkship experiences comprised of 56 students through July 27, 2020. Through analysis of the students’ performance on a national standardized EM shelf exam, students participating in this virtual clerkship demonstrated a fund of knowledge that was not significantly different from that of their peers who completed a traditional clerkship in the specialty prior to the pandemic interruptions. Additionally, the critical review of the traditional course created the opportunity to make improvements and enrich the medical student educational experience in a virtual environment and upon resumption of the traditional course when students returned to the in-person environment. The resources provided for those interested in adopting our pedagogical approach include a course syllabus, calendar, and learner summative assessment.
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- 2021
26. Passivation of the CuInSe2 surface via cadmium pre-electrolyte treatment
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Boumenou, Christian Kameni, Babbe, Finn, Elizabeth, Amala, Melchiorre, Michele, Spindler, Conrad, Guillot, Jérome, Mönig, Harry, Siebentritt, Susanne, and Redinger, Alex
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Physical Sciences ,Engineering ,Materials Engineering ,Nanotechnology ,Macromolecular and materials chemistry ,Materials engineering ,Condensed matter physics - Abstract
Effective defect passivation of semiconductor surfaces and interfaces is indispensable for the development of high efficiency solar cells. In this study we systematically investigated the surface and grain boundary properties of CuInSe2 (CISe) with scanning tunneling microscopy (STM) and spectroscopy (STS) after different surface treatments such as potassium cyanide (KCN) etching, pre-electrolyte treatment with cadmium ions, and annealing in ultrahigh vacuum (UHV). We show that air exposed samples with a subsequent KCN etching step exhibits a highly defective surface. However, a Cd pre-electrolyte treatment passivates most of these defects, which manifests itself by a reduction of the high conductance in the STS measurements at positive sample biases. The origin of the improvement can be traced back to an increase in surface band bending, which leads to a type inversion, induced by a change in the concentration of Cu vacancies. We observe a defect passivation at the CISe surface and at the grain boundaries. Our results give a direct explanation of why the CdS buffer layer in CISe thin film solar cells is of utmost importance for high efficiency devices.
- Published
- 2020
27. Π-Π interactions stabilize PeptoMicelle-based formulations of Pretomanid derivatives leading to promising therapy against tuberculosis in zebrafish and mouse models
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Dal, Nils-Jørgen K., Schäfer, Gabriela, Thompson, Andrew M., Schmitt, Sascha, Redinger, Natalja, Alonso-Rodriguez, Noelia, Johann, Kerstin, Ojong, Jessica, Wohlmann, Jens, Best, Andreas, Koynov, Kaloian, Zentel, Rudolf, Schaible, Ulrich E., Griffiths, Gareth, Barz, Matthias, and Fenaroli, Federico
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- 2023
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28. Variable stoichiometric and macronutrient responses to lizard predation in Ozark glade grasshopper communities
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Redinger, Joseph M., Halvorson, Halvor M., and Gifford, Matthew E.
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- 2022
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29. A Multicenter Observational Study Comparing Virtual with In-Person Morning Reports during the COVID-19 Pandemic
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Bradley, Joel M., Redinger, Jeffrey W., Tuck, Matthew G., Sweigart, Joseph R., Smeraglio, Andrea C., Mitchell, Christine A., Laudate, James D., Kwan, Brian K., Jagannath, Anand D., Heppe, Daniel B., Guidry, Michelle M., Ehlers, Erik T., Cyr, Jessica E., Cornia, Paul B., Chun, Jonathan W., Caputo, Laura M., Arundel, Cherinne, Albert, Tyler J., and Gunderson, Craig G.
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- 2023
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30. POS0191 A LUPUS FLARE RISK INDEX INFORMED BY SELECT ADAPTIVE AND TNF SUPERFAMILY IMMUNE MEDIATORS: VALIDATION IN A CONFIRMATORY COHORT
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Munroe, M. E., primary, Blankenship, D., additional, Defreese, D., additional, Holloway, A., additional, Purushothaman, M., additional, Dejager, W., additional, Macwana, S., additional, Guthridge, J. M., additional, Kamp, S., additional, Redinger, N., additional, Aberle, T., additional, Chakravary, E. F., additional, Arriens, C., additional, LI, Y., additional, Zeng, H., additional, Dezzutti, S., additional, Izmirly, P., additional, Thanarajasingam, U., additional, Kamen, D. L., additional, Buyon, J. P., additional, James, J. A., additional, and Jupe, E., additional
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- 2024
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31. OP0255 SELECT SOLUBLE MEDIATORS INFORM A REFINED LUPUS DISEASE ACTIVITY IMMUNE INDEX THAT CHARACTERIZES CLINICAL DISEASE ACTIVITY IN SYSTEMIC LUPUS ERYTHEMATOSUS
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Munroe, M. E., primary, Blankenship, D., additional, Defreese, D., additional, Holloway, A., additional, Purushothaman, M., additional, Dejager, W., additional, Macwana, S., additional, Guthridge, J. M., additional, Kamp, S., additional, Redinger, N., additional, Aberle, T., additional, Chakravary, E. F., additional, Arriens, C., additional, LI, Y., additional, Zeng, H., additional, Dezzutti, S., additional, Izmirly, P., additional, Thanarajasingam, U., additional, Kamen, D. L., additional, Buyon, J. P., additional, James, J. A., additional, and Jupe, E., additional
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- 2024
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32. Grain boundaries are not the source of Urbach tails in Cu(In,Ga)Se2 absorbers
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Sevan Gharabeiki, Muhammad Uzair Farooq, Taowen Wang, Mohit Sood, Michele Melchiorre, Christian A Kaufmann, Alex Redinger, and Susanne Siebentritt
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CIGSe ,Urbach tails ,grain boundaries ,photoluminescence ,Kelvin probe force microscopy ,alkali post deposition treatment ,Production of electric energy or power. Powerplants. Central stations ,TK1001-1841 ,Renewable energy sources ,TJ807-830 - Abstract
The presence of Urbach tails in Cu(In,Ga)Se _2 (CIGSe) absorbers has been identified as a limiting factor for the performance of the CIGSe solar cells. The tail states contribute to both radiative and non-radiative recombination processes, ultimately leading to a reduction in the open-circuit voltage and, consequently, decreasing the overall efficiency of CIGSe devices. Urbach tails result from structural and thermal disorders. The Urbach tails can be characterized by the Urbach energy, which is associated with the magnitude of the tail states. Within polycrystalline CIGSe absorbers, grain boundaries can be considered as structural disorder and, therefore, can potentially contribute to the Urbach tails. In fact, it has been proposed that the band bending at grain boundaries contribute significantly to the tail states. This study focuses on examining the correlation between Urbach tails and the band bending at the grain boundaries. The Urbach energies of the CIGSe samples are extracted from photoluminescence (PL) measurements, which reveal that the introduction of Sodium (Na) into the material can lead to a reduction in the Urbach energy, and an even further decrease can be achieved through the RbF post-deposition treatment. The band bending at the grain boundaries is investigated by Kelvin probe force microscopy measurements. A thorough statistical analysis of more than 340 grain boundaries does not show any correlation between Urbach tails and grain boundaries. We measure small band bending values at the grain boundaries, in the range of the thermal energy (26 meV at room temperature). Furthermore, our intensity dependent PL measurements indicate that Urbach tails are, at least in part, a result of electrostatic potential fluctuations. This supports the model that the introduction of alkali elements mainly decreases the magnitude of electrostatic potential fluctuations, resulting in a subsequent reduction in the Urbach energy.
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- 2024
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33. Single-crystalline TiO2 nanoparticles for stable and efficient perovskite modules
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Ding, Yong, Ding, Bin, Kanda, Hiroyuki, Usiobo, Onovbaramwen Jennifer, Gallet, Thibaut, Yang, Zhenhai, Liu, Yan, Huang, Hao, Sheng, Jiang, Liu, Cheng, Yang, Yi, Queloz, Valentin Ianis Emmanuel, Zhang, Xianfu, Audinot, Jean-Nicolas, Redinger, Alex, Dang, Wei, Mosconic, Edoardo, Luo, Wen, De Angelis, Filippo, Wang, Mingkui, Dörflinger, Patrick, Armer, Melina, Schmid, Valentin, Wang, Rui, Brooks, Keith G., Wu, Jihuai, Dyakonov, Vladimir, Yang, Guanjun, Dai, Songyuan, Dyson, Paul J., and Nazeeruddin, Mohammad Khaja
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- 2022
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34. Internal Medicine Residents’ Perceptions of Virtual Morning Report: a Multicenter Survey
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Albert, Tyler J., Bradley, Joel, Starks, Helene, Redinger, Jeff, Arundel, Cherinne, Beard, Albertine, Caputo, Laura, Chun, Jonathan, Gunderson, Craig G., Heppe, Dan, Jagannath, Anand, Kent, Kyle, Krug, Michael, Laudate, James, Palaniappan, Vignesh, Pensiero, Amanda, Sargsyan, Zaven, Sladek, Emily, Tuck, Matthew, and Cornia, Paul B.
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- 2022
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35. Adsorption and Intermolecular Interaction of Cobalt Phthalocyanine on CoO(111) Ultrathin Films: An STM and DFT Study
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Schmitt, Tobias, Ferstl, Pascal, Hammer, Lutz, Schneider, M. Alexander, and Redinger, Josef
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Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
We investigate the adsorption of cobalt phthalocyanine (CoPc) molecules on a thin layer of cobalt oxide grown on Ir(100). To that end we compare the results of low-temperature scanning tunneling microscopy (STM) with those of ab-initio density functional theory (DFT) calculations and reveal the adsorption geometry. We find that the CoPc molecules lie flat on the surface and that their central cobalt atom forms a chemical bond to a substrate oxygen ion. However, this bond contributes only modestly to the adsorption energy, while van-der-Waals forces dominate the potential landscape and determine to a large extend the geometry as well as the distortion of substrate and molecule. Furthermore they lead to attractive molecule-molecule interactions at higher molecular coverages. The DFT calculations predict energetic positions of the molecular orbitals which are compared to scanning tunneling spectroscopy (STS) measurements., Comment: 14 pages, 5 figures
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- 2018
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36. Monatomic Co, CoO$_2$, and CoO$_3$ Nanowires on Ir(100) and Pt(100) surfaces: Formation, Structure, and Energetics
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Ferstl, P., Mittendorfer, F., Redinger, J., Schneider, M. A., and Hammer, L.
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Condensed Matter - Materials Science - Abstract
In this study we investigate the structural and chemical changes of monatomic CoO$_2$ chains grown self-organized on the Ir(100) surface [P. Ferstl et al., PRL 117, 2016, 046101] and on Pt(100) under reducing and oxidizing conditions. By a combination of quantitative low-energy electron diffraction, scanning tunnelling microscopy, and density functional theory we show that the cobalt oxide wires are completely reduced by H$_2$ at temperatures above 320 K and a 3x1 ordered Ir$_2$Co or Pt$_2$Co surface alloy is formed. Depending on temperature the surface alloy on Ir(100) is either hydrogen covered (T < 400 K) or clean and eventually undergoes an irreversible order-disorder transition at about 570 K. The Pt$_2$Co surface alloy disorders with the desorption of hydrogen, whereby Co submerges into subsurface sites. Vice versa, applying stronger oxidants than O$_2$ such as NO$_2$ leads to the formation of CoO3 chains on Ir(100) in a 3x1 superstructure. On Pt(100) such a CoO$_3$ phase could not be prepared so far, which however, is due to the UHV conditions of our experiments. As revealed by theory this phase will become stable in a regime of higher pressure. In general, the structures can be reversibly switched on both surfaces using the respective agents O$_2$, NO$_2$ and H$_2$., Comment: 13 pages, 10 figures
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- 2018
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37. The perovskite/transport layer interfaces dominate non-radiative recombination in efficient perovskite solar cells
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Stolterfoht, Martin, Caprioglio, Pietro, Wolff, Christian M., Márquez, José A., Nordmann, Joleik, Zhang, Shanshan, Rothhardt, Daniel, Hörmann, Ulrich, Redinger, Alex, Kegelmann, Lukas, Albrecht, Steve, Kirchartz, Thomas, Saliba, Michael, Unold, Thomas, and Neher, Dieter
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Physics - Applied Physics - Abstract
Charge transport layers (CTLs) are key components of diffusion controlled perovskite solar cells, however, they can induce additional non-radiative recombination pathways which limit the open circuit voltage (V_OC) of the cell. In order to realize the full thermodynamic potential of the perovskite absorber, both the electron and hole transport layer (ETL/HTL) need to be as selective as possible. By measuring the quasi-Fermi level splitting (QFLS) of perovskite/CTL heterojunctions, we quantify the non-radiative interfacial recombination current for a wide range of commonly used CTLs, including various hole-transporting polymers, spiro-OMeTAD, metal oxides and fullerenes. We find that all studied CTLs limit the V_OC by inducing an additional non-radiative recombination current that is significantly larger than the loss in the neat perovskite and that the least-selective interface sets the upper limit for the V_OC of the device. The results also show that the V_OC equals the internal QFLS in the absorber layer of (pin, nip) cells with selective CTLs and power conversion efficiencies of up to 21.4%. However, in case of less selective CTLs, the V_OC is substantially lower than the QFLS which indicates additional losses at the contacts and/or interfaces. The findings are corroborated by rigorous device simulations which outline several important considerations to maximize the V_OC. This work shows that the real challenge to supress non-radiative recombination losses in perovskite cells on their way to the radiative limit lies in the suppression of carrier recombination at the perovskite/CTL interfaces., Comment: Update of Figure 3 and Figure S9 and new Figure S10 added
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- 2018
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38. Adsorption of CO on the Ca3Ru2O7(001) surface
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Mayr-Schmölzer, Wernfried, Halwidl, Daniel, Mittendorfer, Florian, Schmid, Michael, Diebold, Ulrike, and Redinger, Josef
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Condensed Matter - Materials Science - Abstract
The adsorption of CO molecules at the Ca3Ru2O7(001) surface was studied using low-temperature scanning tunneling microscopy (STM) and density functional theory (DFT). Ca3Ru2O7 can be easily cleaved along the (001) plane, yielding a smooth, CaO-terminated surface. The STM shows a characteristic pattern with alternating dark and bright stripes, resulting from the tilting of the RuO$_6$ octahedra. At 78,K, CO adsorbs at an apical surface O at the channel edge with a predicted binding energy of $E_{ads} = -0.85$eV. After annealing at room temperature, the CO forms a strong bond ($E_{ads}= -2.04$eV) with the apical O and the resulting carboxylate takes the place of the former surface O. This carboxylate can be decomposed by scanning the surface with a high sample bias voltage of +2.7V, restoring the original surface.
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- 2018
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39. Adsorption of a superoxo O2- species on the pure an Ca doped Sr3Ru2O7(001) surface
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Mayr-Schmölzer, Wernfried, Mittendorfer, Florian, and Redinger, Josef
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Condensed Matter - Materials Science - Abstract
Only recently, the activation of oxygen molecules on clean defect-free transition metal oxide surfaces has been reported, for example on the CaO-terminated surface of the Ruddelsden-Popper perovskite \crosurf. In this work we show that oxygen molecules adsorb as an activated superoxo species on a clean SrO-terminated surface of \srosurf. At all coverages, the electrons activating the molecule originate from the subsurface RuO$_2$ layer. At low coverages, the presence of a Ca dopant in the terminating SrO layer slightly increases the adsorption energy. At high coverage, DFT predicts a flat potential energy surface and a preferred adsorption of the \oom\ near surface cations. Advanced many-electron calculations (RPA) predict adsorption energies of $-0.99$\,eV and $-0.49$\,eV per \oom~molecule for low and high coverages, respectively, and a preference for forming line-like structures in the latter case.
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- 2018
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40. Adsorption of water at the SrO surface of ruthenates
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Halwidl, Daniel, Stöger, Bernhard, Mayr-Schmölzer, Wernfried, Pavelec, Jiri, Fobes, David, Peng, Jin, Mao, Zhiqiang, Parkinson, Gareth S., Schmid, Michael, Mittendorfer, Florian, Redinger, Josef, and Diebold, Ulrike
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Condensed Matter - Materials Science - Abstract
Although perovskite oxides hold promise in applications ranging from solid oxide fuel cells to catalysts, their surface chemistry is poorly understood at the molecular level. Here we follow the formation of the first monolayer of water at the (001) surfaces of Sr$_{n+1}$Ru$_n$O$_{3n+1}$ ($n$ = 1, 2) using low-temperature scanning tunnelling microscopy, X-ray photoelectron spectroscopy, and density functional theory. These layered perovskites cleave between neighbouring SrO planes, yielding almost ideal, rocksalt-like surfaces. An adsorbed monomer dissociates and forms a pair of hydroxide ions. The OH stemming from the original molecule stays trapped at Sr-Sr bridge positions, circling the surface OH with a measured activation energy of 187 $\pm$ 10 meV. At higher coverage, dimers of dissociated water assemble into one-dimensional chains and form a percolating network where water adsorbs molecularly in the gaps. Our work shows the limitations of applying surface chemistry concepts derived for binary rocksalt oxides to perovskites.
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- 2018
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41. High chemical activity of a perovskite surface: reaction of CO with Sr$_3$Ru$_2$O$_7$
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Stöger, Bernhard, Hieckel, Marcel, Mittendorfer, Florian, Wang, Zhiming, Fobes, David, Peng, Jin, Mao, Zhiqiang, Schmid, Michael, Redinger, Josef, and Diebold, Ulrike
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Condensed Matter - Materials Science - Abstract
Adsorption of CO at the Sr$_3$Ru$_2$O$_7$(001) surface was studied with low-temperature scanning tunneling microscopy (STM) and density functional theory. In situ cleaved single crystals terminate in an almost perfect SrO surface. At 78 K, CO first populates impurities and then adsorbs above the apical surface O with a binding energy E$_\mathrm{ads}$=-0.7 eV. Above 100 K, this physisorbed CO replaces the surface O, forming a bent CO2 with the C end bound to the Ru underneath. The resulting metal carboxylate (Ru-COO) can be desorbed by STM manipulation. A low activation (0.2 eV) and high binding (-2.2 eV) energy confirm a strong reaction between CO and regular surface sites of Sr$_3$Ru$_2$O$_7$; likely, this reaction causes the "UHV aging effect" reported for this and other perovskite oxides.
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- 2018
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42. Point defects at cleaved Sr$_{n+1}$Ru$_n$O$_{3n+1}$(001) surfaces
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Stöger, Bernhard, Hieckel, Marcel, Mittendorfer, Florian, Wang, Zhiming, Schmid, Michael, Parkinson, Gareth S., Fobes, David, Peng, Jin, Ortmann, John. E., Limbeck, Andreas, Mao, Zhiqiang, Redinger, Josef, and Diebold, Ulrike
- Subjects
Condensed Matter - Materials Science - Abstract
The (001) surfaces of cleaved Sr$_3$Ru$_2$O$_7$ and Sr$_2$RuO$_4$ samples were investigated using low-temperature scanning tunneling microscopy and density functional theory calculations. Intrinsic defects are not created during cleaving. This experimental observation is consistent with calculations, where the formation energy for a Sr and O vacancy, 4.19 eV and 3.81 eV, respectively, is significantly larger than that required to cleave the crystal, 1.11 eV/(1 $\times$ 1) unit cell. Surface oxygen vacancies can be created through electron bombardment, however, and their appearance is shown to vary strongly with the imaging conditions. Point defects observed on as-cleaved surfaces result from bulk impurities and adsorption from the residual gas.
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- 2018
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43. Pt$_3$Zr(0001): A substrate for growing well-ordered ultrathin zirconia films by oxidation
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Antlanger, Moritz, Mayr-Schmölzer, Wernfried, Pavelec, Jiří, Mittendorfer, Florian, Redinger, Josef, Varga, Peter, Diebold, Ulrike, and Schmid, Michael
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Condensed Matter - Materials Science - Abstract
We have studied the surface of pure and oxidized Pt$_3$Zr(0001) by scanning tunneling microscopy (STM), Auger electron microscopy, and density functional theory (DFT). The well-annealed alloy surface shows perfect long-range chemical order. Occasional domain boundaries are probably caused by nonstoichiometry. Pt$_3$Zr exhibits ABAC stacking along [0001]; only the A-terminated surfaces are seen by STM, in agreement with DFT results showing a lower surface energy for the A termination. DFT further predicts a stronger inward relaxation of the surface Zr than for Pt, in spite of the larger atomic size of Zr. A closed ZrO$_2$ film is obtained by oxidation in $10^{-7}$ mbar O$_2$ at 400 $^\circ$C and post-annealing at $\approx 800 ^\circ$C. The oxide consists of an O-Zr-O trilayer, equivalent to a (111) trilayer of the fluorite structure of cubic ZrO$_2$, but contracted laterally. The oxide forms a $(\sqrt{19} \times \sqrt{19})$R23$^\circ$ superstructure. The first monolayer of the substrate consists of Pt and contracts, similar to the metastable reconstruction of pure Pt(111). DFT calculations show that the oxide trilayer binds rather weakly to the substrate. In spite of the O-terminated oxide, bonding to the substrate mainly occurs via the Zr atoms in the oxide, which strongly buckle down towards the Pt substrate atoms, if near a Pt position. According to DFT, the oxide has a bandgap; STM indicates that the conduction band minimum lies $\approx 2.3$ eV above $E_\mathrm{F}$.
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- 2018
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44. Cross-sectional associations between mental health indicators and social vulnerability, with physical activity, sedentary behaviour and sleep in urban African young women
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Catherine E. Draper, Caylee J. Cook, Stephanie Redinger, Tamsen Rochat, Alessandra Prioreschi, Dale E. Rae, Lisa J. Ware, Stephen J. Lye, and Shane A. Norris
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Low- and middle-income country ,Physical activity ,Sedentary behaviour ,Sleep ,Mental health ,Nutritional diseases. Deficiency diseases ,RC620-627 ,Public aspects of medicine ,RA1-1270 - Abstract
Abstract Background Relationships between mental health and multiple health behaviours have not been explored in young South African women experiencing social constraints. The aim of this study was to identify associations between mental health indicators and risk factors with physical activity, sedentary behaviour, and sleep, amongst young women living in Soweto, a predominantly low-income, urban South African setting. Methods For this cross-sectional study, baseline measurements for participants (n = 1719, 18.0–25.9 years old) recruited for the Healthy Life Trajectories Initiative were used including: physical activity, sedentary behaviour (sitting, screen and television time), sleep (duration and quality), depression and anxiety indicators, emotional health, adverse childhood experiences, alcohol-use risk; social vulnerability, self-efficacy, and social support. Results Multiple regression analyses showed that depression (β = 0.161, p
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- 2022
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45. Complex reactions on a convertible catalyst surface: A study of the S-O-Cu system
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Dürrbeck, S, Shi, X-R, Samadashvili, M, Redinger, J, Bertel, E, and Salmeron, M
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Chemical Sciences ,Physical Chemistry ,Condensed Matter Physics ,Quantum Physics ,Physical Chemistry (incl. Structural) ,Chemical Physics ,Physical chemistry ,Condensed matter physics ,Quantum physics - Abstract
The interaction of clean and partially oxidized Cu(110) with sulphur was studied by scanning tunneling microscopy and density functional theory calculations in the low-coverage range. On the clean Cu surface individual S atoms adsorb in the troughs between the Cu atom rows. Hollow sites are preferred, but long-bridge sites are occasionally occupied as well. The majority of adsorbed S, however, seems to be involved in the formation of highly mobile CuxSy clusters of various sizes. The clusters preferentially attach to steps thus changing the step morphology completely. Some of the clusters form aggregates on the terraces. On the partially oxidized surface similar clusters form and cause long-range mass transport to steps. Additionally, nanowires form in [001] direction on and along the surface oxide stress domains. These nanowires have a complex composition, exhibit different corrugations and appear sometimes as three-dimensional needles. Occasionally they flip their direction by 90°, but doing so they partially decompose. Finally, annealing of the S-O-Cu surface leads to consumption of the surface oxide stripes indicating loss of oxygen presumably via SO2 formation. Simultaneously, linear sulphur chains suspended between the [001] –O-Cu-O- chains form in [11¯0] direction. The surprising multitude of processes and products even at low-pressure, low-temperature conditions in the comparatively simple S-O-Cu system highlights the difficulty of controlling reactivity and selectivity on such convertible catalyst surfaces.
- Published
- 2018
46. The Effect of an Insectivorous Lizard Predator (Crotaphytus collaris) on Ozark Glade Orthopteran Assemblages
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Redinger, Joseph M. and Gifford, Matthew E.
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Biological sciences ,Earth sciences - Abstract
Insectivorous lizards can alter arthropod community structure and composition. Collared lizards (Crotaphytus collaris) are believed to be keystone predators for Ozark glade grasshopper (Orthoptera) communities by increasing species richness on smaller glades. However, the interaction between collared lizard presence and glade area on orthopteran species richness has been inconsistent between studies on glades in southeastern Missouri. In this study, we explored the effects of collared lizard presence on orthopteran abundance, diversity, and assemblage composition in Ozark glades located in northern Arkansas. We found the presence of predatory collared lizard populations significantly affected orthopteran assemblage composition. However, the presence of collared lizards did not affect orthopteran abundance or diversity. Additionally, there were no interaction effects between collared lizard presence and glade area on orthopteran assemblages. We did find that month had the most consistent effect on orthopteran abundance, diversity, anti assemblage composition. These results contrast with other studies that indicate collared lizards influence orthopteran species richness on other glade communities within the region. In this study, seasonal effects, glade area, and unmeasured bottom-up effects appear more important for determining orthopteran diversity than predation. Our results provide further evidence that the strength of top-down effects can vary across a predator's range and could have implications for glade restoration plans in the region., INTRODUCTION Predation is a fundamental environmental factor that influences species diversity and community composition at lower trophic levels (Hairston et al, 1960; Paine, 1969; Menge and Sutherland, 1976; Terborgh et [...]
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- 2022
47. Cross-sectional associations between mental health indicators and social vulnerability, with physical activity, sedentary behaviour and sleep in urban African young women
- Author
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Draper, Catherine E., Cook, Caylee J., Redinger, Stephanie, Rochat, Tamsen, Prioreschi, Alessandra, Rae, Dale E., Ware, Lisa J., Lye, Stephen J., and Norris, Shane A.
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- 2022
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48. Suppression of material transfer at contacting surfaces: The effect of adsorbates on Al/TiN and Cu/diamond interfaces from first-principles calculations
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Feldbauer, Gregor, Wolloch, Michael, Bedolla, Pedro O., Redinger, Josef, Vernes, András, and Mohn, Peter
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Condensed Matter - Materials Science - Abstract
The effect of monolayers of oxygen (O) and hydrogen (H) on the possibility of material transfer at aluminium/titanium nitride (Al/TiN) and copper/diamond (Cu/C$_{\text{dia}}$) interfaces, respectively, were investigated within the framework of density functional theory (DFT). To this end the approach, contact, and subsequent separation of two atomically flat surfaces consisting of the aforementioned pairs of materials were simulated. These calculations were performed for the clean as well as oxygenated and hydrogenated Al and C$_{\text{dia}}$ surfaces, respectively. Various contact configurations were considered by studying several lateral arrangements of the involved surfaces at the interface. Material transfer is typically possible at interfaces between the investigated clean surfaces; however, the addition of O to the Al and H to the C$_{\text{dia}}$ surfaces was found to hinder material transfer. This passivation occurs because of a significant reduction of the adhesion energy at the examined interfaces, which can be explained by the distinct bonding situations., Comment: 27 pages, 8 figures
- Published
- 2017
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49. Mind-Body Classroom Strategies: Techniques to Reduce Elementary Student Stress Following Active Shooter Drills.
- Author
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Biber, Duke D. and Redinger, Amanda
- Abstract
Active shooter drills are widely used in schools throughout the United States, with more than 92% of public schools having an active shooter plan. These drills can increase student stress and anxiety and can have a variety of negative effects, such as somatic complaints, anxiety, poor self-regulation of emotions and behaviors, risk for depression, and prevalence of obesity and eating disorders. This article describes the efficacy of physical activity breaks, mindful breathing techniques, and emotional regulation strategies to reduce stress reactivity and enhance recovery in elementary-age students following active shooter safety drills. A list of example activities is provided for each of the three stress management categories. Each of the activities can be adapted to various developmental levels (i.e., K-12), settings (i.e., classroom, hallway, outdoors), and time availability (i.e., one minute to 10 minutes). The strategies may also be utilized following other emergency drills or during other times of high student and classroom stress. [ABSTRACT FROM AUTHOR]
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- 2024
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50. Tin Halide Perovskite Epitaxial Films on Gold Surfaces: Atomic Structure and Stability.
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Abbasli, Madad, Hieulle, Jeremy, Schrage, Jenny, Wilks, Dina, Samad, Abdus, Schwingenschlögl, Udo, Redinger, Alex, Busse, Carsten, and Ohmann, Robin
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LOW energy electron diffraction ,SCANNING tunneling microscopy ,THIN films ,PHOTOELECTRON spectroscopy ,VACUUM deposition - Abstract
Tin‐based halide perovskite solar cells can be efficient and environmentally friendly substitutions to lead‐based halide perovskite solar cells, but they have a drawback due to oxidation from Sn2+ to Sn4+. Using vacuum deposition, epitaxially aligned CsSnBr3 ultrathin films are prepared on Au(111) and Au(100) and characterized with scanning tunneling microscopy (STM), low‐energy electron diffraction (LEED), and X‐ray photoelectron spectroscopy (XPS). By co‐evaporation of the precursor molecules CsBr and SnBr2, few monolayers of perovskite are obtained. On Au(111), CsSnBr3 grows in three differently oriented domains due to the hexagonal symmetry of the substrate. On Au(100), which has square symmetry, identical to CsSnBr3, but with about half the lattice constant of the perovskite, a (2×2) superstructure is observed. The perovskite is terminated with the (001) facet showing a square surface structure in agreement with density functional theory (DFT) calculations. Chemical analysis is performed in ultra‐high vacuum (UHV) conditions and no indication of a tin oxidation state higher than Sn2+ is found in the films. However, after exposure to air, rapid and severe changes in the films are observed, highlighting the importance of preparing tin perovskites in a controlled environment to maintain their stability and avoid oxidation‐related issues. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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