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- ItemSynthesis and Characterization of Oxide Chloride Sr2VO3Cl, a Layered S = 1 Compound(Washington, DC : ACS Publications, 2023) Sannes, Johnny A.; Kizhake Malayil, Ranjith K.; Corredor, Laura T.; Wolter, Anja U. B.; Grafe, Hans-Joachim; Valldor, MartinThe mixed-anion compound with composition Sr2VO3Cl has been synthesized for the first time, using the conventional high-temperature solid-state synthesis technique in a closed silica ampule under inert conditions. This compound belongs to the known Sr2TmO3Cl (Tm = Sc, Mn, Fe, Co, Ni) family, but with Tm = V. All homologues within this family can be described with the tetragonal space group P4/nmm (No. 129); from a Rietveld refinement of powder X-ray diffraction data on the Tm = V homologue, the unit cell parameters were determined to a = 3.95974(8) and c = 14.0660(4) Å, and the atomic parameters in the crystal structure could be estimated. The synthesized powder is black, implying that the compound is a semiconductor. The magnetic investigations suggest that Sr2VO3Cl is a paramagnet at high temperatures, exhibiting a μeff = 2.0 μB V-1 and antiferromagnetic (AFM) interactions between the magnetic vanadium spins (θCW = −50 K), in line with the V-O-V advantageous super-exchange paths in the V-O layers. Specific heat capacity studies indicate two small anomalies around 5 and 35 K, which however are not associated with long-range magnetic ordering. 35Cl ss-NMR investigations suggest a slow spin freezing below 4.2 K resulting in a glassy-like spin ground state.
- ItemSynthesis and crystal structure of a one-dimensional chain-like strontium(II) coordination polymer built of N-methyldiethanolamine and isobutyrate ligands(Chester : International Union of Crystallography, 2021) Seiss, Maximilian; Schmitz, Sebastian; Börner, Martin; Monakhov, Kirill Yu.The one-dimensional coordination polymer (I) [Sr(ib)2 (H2mda)]n (Hib = isobutyric acid, C4H8O2, and H2mda = N-methyldiethanolamine, C5H13NO2), namely, catena-poly[[(N-methyldiethanolamine-k3O, N, O')strontium(II)]-di-μ2- isobutyrato-K3O, O':O;K3O:O, O'], was prepared by the one-pot aerobic reaction of [Zr6O4 (OH)4 (ib)12 (H2O)].3Hib with Sr(NO3)2 and H2mda in the presence of MnCl2 and Et3N in acetonitrile. The use of MnCl2 is key to the isolation of I as high-quality colorless crystals in good yield. The molecular solid-state structure of I was determined by single-crystal X-ray diffraction. Compound I crystallizes in the monoclinic space group P21/c and shows a one-dimensional polymeric chain structure. Each monomeric unit of this coordination polymer consists of a central SrII ion in the NO8 coordination environment of two deprotonated ib- ligands and one fully protonated H2mda ligand. The C and O atoms of the H2mda ligand were refined as disordered over two sets of sites with site occupancies of 0.619 (3) and 0.381 (3). Compound I shows thermal stability up to 130°C in air. © 2021 International Union of Crystallography. All rights reserved.
- ItemSingle-crystal neutron and X-ray diffraction study of garnet-type solid-state electrolyte Li6La3ZrTaO12: An in situ temperature-dependence investigation (2.5 ≤ T ≤ 873 K)(Oxford [u.a.] : Wiley-Blackwell, 2021) Redhammer, Günther J.; Meven, Martin; Ganschow, Steffen; Tippelt, Gerold; Rettenwander, DanielLarge single crystals of garnet-type Li6La3ZrTaO12 (LLZTO) were grown by the Czochralski method and analysed using neutron diffraction between 2.5 and 873 K in order to fully characterize the Li atom distribution, and possible Li ion mobility in this class of potential candidates for solid-state electrolyte battery material. LLZTO retains its cubic symmetry (space group Ia 3 d) over the complete temperature range. When compared to other sites, the octahedral sites behave as the most rigid unit and show the smallest increase in atomic displacement parameters and bond length. The La and Li sites show similar thermal expansion in their bond lengths with temperature, and the anisotropic and equivalent atomic displacement parameters exhibit a distinctly larger increase at temperatures above 400 K. Detailed inspection of nuclear densities at the Li1 site reveal a small but significant displacement from the 24d position to the typical 96h position, which cannot, however, be resolved from the single-crystal X-ray diffraction data. The site occupation of LiI ions on Li1 and Li2 sites remains constant, so there is no change in site occupation with temperature. © 2021 International Union of Crystallography. All rights reserved.
- ItemBlind Super-Resolution Approach for Exploiting Illumination Variety in Optical-Lattice Illumination Microscopy(Washington, DC : ACS Publications, 2021) Samanta, Krishnendu; Sarkar, Swagato; Acuña, Sebastian; Joseph, Joby; Ahluwalia, Balpreet Singh; Agarwal, KrishnaOptical-lattice illumination patterns help in pushing high spatial frequency components of the sample into the optical transfer function of a collection microscope. However, exploiting these high-frequency components require precise knowledge of illumination if reconstruction approaches similar to structured illumination microscopy are employed. Here, we present an alternate blind reconstruction approach that can provide super-resolution without the requirement of extra frames. For this, the property of exploiting temporal fluctuations in the sample emissions using “multiple signal classification algorithm” is extended aptly toward using spatial fluctuation of phase-modulated lattice illuminations for super-resolution. The super-resolution ability is shown for sinusoidal and multiperiodic lattice with approximately 3- and 6-fold resolution enhancements, respectively, over the diffraction limit. © 2021 The Authors. Published by American Chemical Society
- ItemStrain Engineered Electrically Pumped SiGeSn Microring Lasers on Si(Washington, DC : ACS, 2022) Marzban, Bahareh; Seidel, Lukas; Liu, Teren; Wu, Kui; Kiyek, Vivien; Zoellner, Marvin Hartwig; Ikonic, Zoran; Schulze, Joerg; Grützmacher, Detlev; Capellini, Giovanni; Oehme, Michael; Witzens, Jeremy; Buca, DanSiGeSn holds great promise for enabling fully group-IV integrated photonics operating at wavelengths extending in the mid-infrared range. Here, we demonstrate an electrically pumped GeSn microring laser based on SiGeSn/GeSn heterostructures. The ring shape allows for enhanced strain relaxation, leading to enhanced optical properties, and better guiding of the carriers into the optically active region. We have engineered a partial undercut of the ring to further promote strain relaxation while maintaining adequate heat sinking. Lasing is measured up to 90 K, with a 75 K T0. Scaling of the threshold current density as the inverse of the outer circumference is linked to optical losses at the etched surface, limiting device performance. Modeling is consistent with experiments across the range of explored inner and outer radii. These results will guide additional device optimization, aiming at improving electrical injection and using stressors to increase the bandgap directness of the active material.
- ItemNi-In Synergy in CO2Hydrogenation to Methanol(Washington, DC : ACS Publications, 2021) Zhu, Jiadong; Cannizzaro, Francesco; Liu, Liang; Zhang, Hao; Kosinov, Nikolay; Filot, Ivo A.W.; Rabeah, Jabor; Brückner, Angelika; Hensen, Emiel J.M.Indium oxide (In2O3) is a promising catalyst for selective CH3OH synthesis from CO2but displays insufficient activity at low reaction temperatures. By screening a range of promoters (Co, Ni, Cu, and Pd) in combination with In2O3using flame spray pyrolysis (FSP) synthesis, Ni is identified as the most suitable first-row transition-metal promoter with similar performance as Pd-In2O3. NiO-In2O3was optimized by varying the Ni/In ratio using FSP. The resulting catalysts including In2O3and NiO end members have similar high specific surface areas and morphology. The main products of CO2hydrogenation are CH3OH and CO with CH4being only observed at high NiO loading (≥75 wt %). The highest CH3OH rate (∼0.25 gMeOH/(gcath), 250 °C, and 30 bar) is obtained for a NiO loading of 6 wt %. Characterization of the as-prepared catalysts reveals a strong interaction between Ni cations and In2O3at low NiO loading (≤6 wt %). H2-TPR points to a higher surface density of oxygen vacancy (Ov) due to Ni substitution. X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, and electron paramagnetic resonance analysis of the used catalysts suggest that Ni cations can be reduced to Ni as single atoms and very small clusters during CO2hydrogenation. Supportive density functional theory calculations indicate that Ni promotion of CH3OH synthesis from CO2is mainly due to low-barrier H2dissociation on the reduced Ni surface species, facilitating hydrogenation of adsorbed CO2on Ov © 2021 The Authors. Published by American Chemical Society
- ItemHandreichung Urheberrecht und Datenschutz(Genève : CERN, 2023) Blumtritt, Ute; Euler, Ellen; Fadeevy, Yuliya; Pohle, Jörg; Rack, Fabian; Wrzesinski, MarcelDie vorliegende Handreichung adressiert wissenschaftsgeleitete Zeitschriften sowie herausgebende Einrichtungen. Sie sollen in die Lage versetzt werden, erste urheberrechtliche wie datenschutzrechtliche Fragen zu beantworten und dabei Qualitätsstandards einzuhalten. Dieser Text ersetzt keine Rechtsberatung, sondern bietet grundsätzliche Informationen, gibt Empfehlungen zum Weiterlesen für klassische Fragestellungen und verweist auf gelungene Beispiele im weiteren Feld des wissenschaftsgeleiteten Publizierens.
- ItemMelt Electrowriting of Graded Porous Scaffolds to Mimic the Matrix Structure of the Human Trabecular Meshwork(Washington, DC : ACS Publ., 2022) Włodarczyk-Biegun, Małgorzata K.; Villiou, Maria; Koch, Marcus; Muth, Christina; Wang, Peixi; Ott, Jenna; del Campo, AranzazuThe permeability of the human trabecular meshwork (HTM) regulates eye pressure via a porosity gradient across its thickness modulated by stacked layers of matrix fibrils and cells. Changes in HTM porosity are associated with increases in intraocular pressure and the progress of diseases such as glaucoma. Engineered HTMs could help to understand the structure-function relation in natural tissues and lead to new regenerative solutions. Here, melt electrowriting (MEW) is explored as a biofabrication technique to produce fibrillar, porous scaffolds that mimic the multilayer, gradient structure of native HTM. Poly(caprolactone) constructs with a height of 125-500 μm and fiber diameters of 10-12 μm are printed. Scaffolds with a tensile modulus between 5.6 and 13 MPa and a static compression modulus in the range of 6-360 kPa are obtained by varying the scaffold design, that is, the density and orientation of the fibers and number of stacked layers. Primary HTM cells attach to the scaffolds, proliferate, and form a confluent layer within 8-14 days, depending on the scaffold design. High cell viability and cell morphology close to that in the native tissue are observed. The present work demonstrates the utility of MEW for reconstructing complex morphological features of natural tissues.
- ItemComparative Verification of the Digital Library of Mathematical Functions and Computer Algebra Systems(Berlin ; Heidelberg : Springer, 2022) Greiner-Petter, André; Cohl, Howard S.; Youssef, Abdou; Schubotz, Moritz; Trost, Avi; Dey, Rajen; Aizawa, Akiko; Gipp, Bela; Fisman, Dana; Rosu, GrigoreDigital mathematical libraries assemble the knowledge of years of mathematical research. Numerous disciplines (e.g., physics, engineering, pure and applied mathematics) rely heavily on compendia gathered findings. Likewise, modern research applications rely more and more on computational solutions, which are often calculated and verified by computer algebra systems. Hence, the correctness, accuracy, and reliability of both digital mathematical libraries and computer algebra systems is a crucial attribute for modern research. In this paper, we present a novel approach to verify a digital mathematical library and two computer algebra systems with one another by converting mathematical expressions from one system to the other. We use our previously developed conversion tool (referred to as ) to translate formulae from the NIST Digital Library of Mathematical Functions to the computer algebra systems Maple and Mathematica. The contributions of our presented work are as follows: (1) we present the most comprehensive verification of computer algebra systems and digital mathematical libraries with one another; (2) we significantly enhance the performance of the underlying translator in terms of coverage and accuracy; and (3) we provide open access to translations for Maple and Mathematica of the formulae in the NIST Digital Library of Mathematical Functions.
- ItemHandreichung Technik und Infastrukturen(Genève : CERN, 2023) Eichler, Frederik; Eppelin, Anita; Kampkaspar, Dario; Schrader, Antonia C.; Söllner, Konstanze; Vierkant, Paul; Withanage, Dulip; Wrzesinski, MarcelIn der vorliegenden Handreichung stellen wir unterschiedliche technische Ressourcen vor, die redaktionelle Arbeiten unterstützen können. Dabei empfiehlt es sich, Software und Systeme zu nutzen, die den Wandel hin zu einer offenen, niederschwelligen und nachhaltigen Wissenschaftskultur fördern. Hierzu zählt in erster Linie die Verwendung von Open-Source-Software. Unsere Empfehlungen haben dabei eine begrenzte Reichweite: Serviceanbieter, Software und Projekte sind zu einem späteren Zeitpunkt ggf. nicht mehr verfügbar. Auch sind gerade die Infrastruktureinrichtungen in das föderale Wissenschaftssystem integriert, was sie bestimmten Unwägbarkeiten aussetzt.