@article{64015, abstract = {{Periodate oxidation reaction occurring directly on chitin has been neglected in polysaccharide chemistry so far. Herein, we present the first direct alkaline periodate oxidation of chitin, which demonstrates at the same time a novel approach for the preparation of chitin nanocrystals (ChNCs). This oxidation is based on an unprecedented selective reaction of non-ordered domains of chitin by the dimeric orthoperiodate ions (H2I2O104−) as the major species in alkaline surroundings. Nearly 50 wt% of non-ordered regions are dissolved after sequential accelerated partial deacetylation, periodate oxidation and β-alkoxy fragmentation, which allows the isolation of up to 50 wt% of uniform anisotropic zwitterionic ChNCs.}}, author = {{Liu, Peiwen and Liu, Huan and Schäfer, Timmy and Gutmann, Torsten and Gibhardt, Holger and Qi, Houjuan and Tian, Lin and Zhang, Xizhou Cecily and Buntkowsky, Gerd and Zhang, Kai}}, journal = {{Green Chemistry}}, number = {{2}}, pages = {{745–751}}, publisher = {{The Royal Society of Chemistry}}, title = {{{Unexpected selective alkaline periodate oxidation of chitin for the isolation of chitin nanocrystals}}}, doi = {{10.1039/D0GC04054A}}, volume = {{23}}, year = {{2021}}, } @article{64006, abstract = {{Three chiral dirhodium coordination polymers Rh2–Ln (n = 1–3) have been synthesized via ligand exchange between dirhodium trifluoroacetate Rh2(TFA)4 and differently sized chiral dicarboxylic acids derived from l-tert-leucine. SEM images indicate that the Rh2–Ln (n = 1–3) polymers have a lamellar structure. XPS data demonstrate that the oxidation state of rhodium in the dirhodium nodes is maintained during the synthesis of the polymers. The coordination polymers have been further characterized by FTIR, 1H → 13C CP MAS NMR and 19F MAS NMR spectroscopy to prove the formation of polymers via ligand exchange. Although the quantitative 19F MAS NMR spectra reveal incomplete ligand substitution in the coordination polymers, these catalysts show excellent activity and selectivity in the asymmetric cyclopropanation reaction between styrene and diazooxindole. In particular, the enantioselectivity has been significantly improved compared with previously designed dirhodium coordination polymers, which were synthesized from aromatic dicarboxylic acids derived from l-phenylalanine. Meanwhile, the dirhodium polymers can be easily recycled five times without significant reduction in their catalytic efficiency.}}, author = {{Li, Zhenzhong and Rösler, Lorenz and Wissel, Till and Breitzke, Hergen and Hofmann, Kathrin and Limbach, Hans-Heinrich and Gutmann, Torsten and Buntkowsky, Gerd}}, issn = {{2044-4753}}, journal = {{Catalysis Science & Technology}}, number = {{10}}, pages = {{3481–3492}}, publisher = {{The Royal Society of Chemistry}}, title = {{{Design and characterization of novel dirhodium coordination polymers – the impact of ligand size on selectivity in asymmetric cyclopropanation}}}, doi = {{10.1039/D1CY00109D}}, volume = {{11}}, year = {{2021}}, } @article{64005, abstract = {{A novel immobilized chiral dirhodium catalyst, Rh2(S-PTTL)3(S-PTTL-linker)∼SBA-15 (8), has been prepared via click reaction of azide-groups on functionalized SBA-15 with the dirhodium complex Rh2(S-PTTL)3(S-PTTL-alkyne) (6) containing an alkyne moiety. During the synthesis of this complex, one chiral ligand of the parent Rh2(S-PTTL)4 catalyst is exchanged with an analogous chiral ligand system containing an alkyne moiety, which to a great extent maintains the intrinsic catalytic performance of the catalyst. The heterogeneous dirhodium catalyst is characterized by FT-IR and 13C solid-state NMR to validate the successful immobilization. The catalytic performance of the heterogeneous catalyst 8 is investigated in the asymmetric cyclopropanation of 3-diazooxindole with different aryl alkenes that form spiro-cyclopropyloxindoles which serve as precursors for pharmaceuticals. The resulting heterogeneous catalyst shows high catalytic activity and significant enantioselectivity. Importantly, it can be readily recovered and reused at least four times without significant loss of its catalytic performance.}}, author = {{Li, Zhenzhong and Rösler, Lorenz and Wissel, Till and Breitzke, Hergen and Gutmann, Torsten and Buntkowsky, Gerd}}, journal = {{Journal of CO2 Utilization}}, keywords = {{immobilized catalyst, asymmetric cyclopropanation, Chiral dirhodium}}, pages = {{101682}}, title = {{{Immobilization of a chiral dirhodium catalyst on SBA-15 via click-chemistry: Application in the asymmetric cyclopropanation of 3-diazooxindole with aryl alkenes}}}, doi = {{10.1016/j.jcou.2021.101682}}, volume = {{52}}, year = {{2021}}, } @article{63993, abstract = {{A synthetic strategy to β-silylphospholes with three methoxy, ethoxy, chloro, hydrido, or phenyl substituents at silicon has been developed, starting from trimethoxy, triethoxy, or triphenyl silyl substituted phenyl phosphanides and 1,4-diphenyl-1,3-butadiyne. These trifunctional silylphospholes were attached to the surface of uniform spheric silica particles (15 μm) and, for comparison, to a polyhedral silsesquioxane (POSS)–trisilanol as a molecular model to explore their luminescent properties in comparison with the free phospholes. Density functional theory calculations were performed to investigate any electronic perturbation of the phosphole system by the trifunctional silyl anchoring unit. For the immobilized phospholes, cross-polarization magic-angle-spinning NMR measurements (13C, 29Si, and 31P) were carried out to explore the bonding situation to the silica surface. Thermogravimetric analysis and X-ray photoelectron spectroscopy measurements were performed to approximate the amount of phospholes covering the silica surface. Identity and purity of all novel phospholes have been established with standard techniques (multinuclear NMR, mass spectrometry, and elemental analysis) and X-ray diffraction for the POSS derivative.}}, author = {{Klintuch, Dieter and Höfler, Mark V. and Wissel, Till and Bruhn, Clemens and Gutmann, Torsten and Pietschnig, Rudolf}}, journal = {{Inorganic Chemistry}}, number = {{18}}, pages = {{14263–14274}}, publisher = {{American Chemical Society}}, title = {{{Trifunctional Silyl Groups as Anchoring Units in the Preparation of Luminescent Phosphole–Silica Hybrids}}}, doi = {{10.1021/acs.inorgchem.1c01775}}, volume = {{60}}, year = {{2021}}, } @article{63992, abstract = {{Solid-state NMR combined with dynamic nuclear polarization (DNP NMR) is used to study hydration processes in tricalcium silicate (Ca3SiO5, abbreviated as C3S) samples. The studied C3S samples have experienced early stage hydration (1–30 h) and slow aging (9 years) processes. The appearance of Q3 and Q4 lines in the 29Si MAS and 1H → 29Si CP MAS NMR spectra obtained for partly hydrated C3S samples indicated the formation of amorphous silica which corresponds to their carbonation, which was corroborated by complementary FTIR data. Significant DNP signal enhancements obtained for the studied samples allowed to further investigate the C3S carbonation process in detail employing the 1H → 29Si CP MAS FSLG HETCOR technique. Finally, DNP enhanced 1H → 13C CP MAS and 1H → 13C CP MAS FSLG HETCOR techniques enabled to directly observe the formation of carbonate moieties in partly hydrated C3S samples.}}, author = {{Klimavicius, Vytautas and Hilbig, Harald and Gutmann, Torsten and Buntkowsky, Gerd}}, issn = {{1932-7447}}, journal = {{Journal of Physical Chemistry C}}, number = {{13}}, pages = {{7321–7328}}, publisher = {{American Chemical Society}}, title = {{{Direct Observation of Carbonate Formation in Partly Hydrated Tricalcium Silicate by Dynamic Nuclear Polarization Enhanced NMR Spectroscopy}}}, doi = {{10.1021/acs.jpcc.0c10382}}, volume = {{125}}, year = {{2021}}, } @article{63982, abstract = {{Polyethylene glycol (PEG) is gaining interest as an alternative green solvent in chemical synthesis and processing. This report presents density and viscosity data from 293.15 K to 358.15 K as well as self-diffusion coefficient data from 298.15 K to 358.15 K for oligomers of PEG from di- to nonaethylene glycol. The results were obtained by extrapolation from measurement series where water, the most common impurity in PEGs, was intentionally added in several increments. The obtained results are carefully compared to literature data, which are widely available only for density and viscosity, and only for the lower oligomers. Densities are found to be linearly dependent on temperatures for all studied oligomers. The temperature dependence of viscosity and self-diffusion coefficients show only slight deviations from the Arrhenius equation over the investigated temperature range. The activation energies obtained from the viscosity data agree well with the activation energies from the self-diffusion coefficient data and appear to be linearly dependent with respect to the number of ethylene oxide repeat units in the PEG oligomer. This linearity combined with the observation that the pre-exponential factor appears to be the same for all studied oligomers may serve as a tool to estimate viscosities and self-diffusion coefficients for higher oligomers within the investigated temperature range. The densities of the oligomers all fall within a rather narrow range without a clear trend in homologous series.}}, author = {{Hoffmann, Markus M. and Horowitz, Rachel H. and Gutmann, Torsten and Buntkowsky, Gerd}}, journal = {{Journal of Chemical and Engineering Data}}, number = {{6}}, pages = {{2480–2500}}, publisher = {{American Chemical Society}}, title = {{{Densities, Viscosities, and Self-Diffusion Coefficients of Ethylene Glycol Oligomers}}}, doi = {{10.1021/acs.jced.1c00101}}, volume = {{66}}, year = {{2021}}, } @article{63986, abstract = {{13C and 15N solid-state nuclear magnetic resonance (NMR) combined with dynamic nuclear polarization (DNP) is used to investigate the structure of dye-doped biopolymer-based materials that can be used in amplified spontaneous emission (ASE) experiments. By comparing calligraphic paper prepared from cellulose and scaffolds prepared from chitosan as substrates, differences in the interactions of the carrier material with the dye molecule Calcofluor White are obtained. These are most probably induced by structural changes of the carrier material due to its interaction with water forming hydrogen bonds. Such structural differences may explain the obtained variation of the emission wavelength of Calcofluor White doped on these substrates in ASE experiments.}}, author = {{Höfler, Mark V. and Hoinka, Nicolai and Schäfer, Timmy and Horn, Marilia and Aussenac, Fabien and Fuhrmann-Lieker, Thomas and Gutmann, Torsten}}, issn = {{1932-7447}}, journal = {{Journal of Physical Chemistry C}}, number = {{39}}, pages = {{21550–21558}}, publisher = {{American Chemical Society}}, title = {{{Light Amplification Materials Based on Biopolymers Doped with Dye Molecules—Structural Insights from 15N and 13C Solid-State Dynamic Nuclear Polarization}}}, doi = {{10.1021/acs.jpcc.1c06737}}, volume = {{125}}, year = {{2021}}, } @article{63973, abstract = {{A novel specific spin-labeling strategy for bioactive molecules is presented for eptifibatide (integrilin) an antiplatelet aggregation inhibitor, which derives from the venom of certain rattlesnakes. By specifically labeling the disulfide bridge this molecule becomes accessible for analytical techniques such as Electron Paramagnetic Resonance (EPR) and solid state Dynamic Nuclear Polarization (DNP). The necessary spin-label was synthesized and inserted into the disulfide bridge of eptifibatide via reductive followed by insertion by a double Michael addition under physiological conditions. This procedure is universally applicable for disulfide containing biomolecules and is expected to preserve their tertiary structure with minimal change due to the small size of the label and restoring of the previous disulfide connection. HPLC and MS analysis show the successful introduction of the spin label and EPR spectroscopy confirms its activity. DNP-enhanced solid state NMR experiments show signal enhancement factors of up to 19 in 13C CP MAS experiments which corresponds to time saving factors of up to 361. This clearly shows the high potential of our new spin labeling strategy for the introduction of site selective radical spin labels into biomolecules and biosolids without compromising its conformational integrity for structural investigations employing solid-state DNP or advanced EPR techniques.}}, author = {{Herr, Kevin and Fleckenstein, Max and Brodrecht, Martin and Höfler, Mark V. and Heise, Henrike and Aussenac, Fabien and Gutmann, Torsten and Reggelin, Michael and Buntkowsky, Gerd}}, journal = {{Scientific Reports}}, number = {{1}}, pages = {{13714}}, title = {{{A novel strategy for site selective spin-labeling to investigate bioactive entities by DNP and EPR spectroscopy}}}, doi = {{10.1038/s41598-021-92975-6}}, volume = {{11}}, year = {{2021}}, } @article{63947, abstract = {{The interactions of molecules such as surfactants with solid interfaces are not sufficiently understood since their study is challenging with standard spectroscopic methods. In this work, octanol-d17 as a model system confined in the mesopores of SBA-15 is studied by variable temperature deuterium solid-state NMR, and the findings are compared to those of bulk octanol-d17. The magic angle spinning (MAS) as well as the static, nonspinning case, are investigated, showing that the described observations are independent of the applied NMR method. The 2H NMR spectra of both the bulk and the confined octanol-d17 show a large and a small quadrupolar Pake pattern below the melting point, suggesting a rigid conformation of the observed molecules with a 3-fold jump motion of the terminal CD3-group. Apart from the melting of the solid, no other phase transition is observed for either sample. The confined octanol-d17 forms a pore solid, exhibiting a melting point 38 K lower than bulk octanol-d17. The interactions of the molecule with the mesoporous SBA-15 bring about a distribution of activation energies for the melting process, resulting in a gradual melting process.}}, author = {{Döller, Sonja C. and Brodrecht, Martin and Haro Mares, Nadia B. and Breitzke, Hergen and Gutmann, Torsten and Hoffmann, Markus and Buntkowsky, Gerd}}, issn = {{1932-7447}}, journal = {{Journal of Physical Chemistry C}}, number = {{45}}, pages = {{25155–25164}}, publisher = {{American Chemical Society}}, title = {{{Deuterium NMR Studies of the Solid–Liquid Phase Transition of Octanol-d17 Confined in SBA-15}}}, doi = {{10.1021/acs.jpcc.1c05873}}, volume = {{125}}, year = {{2021}}, } @article{64275, abstract = {{Abstract We explain by elementary means why the existence of a discrete series representation of a real reductive group G implies the existence of a compact Cartan subgroup of G. The presented approach has the potential to generalize to real spherical spaces.}}, author = {{Krötz, Bernhard and Kuit, Job J. and Opdam, Eric M. and Schlichtkrull, Henrik}}, issn = {{0075-4102}}, journal = {{Journal für die reine und angewandte Mathematik (Crelles Journal)}}, number = {{782}}, pages = {{109--119}}, publisher = {{Walter de Gruyter GmbH}}, title = {{{Ellipticity and discrete series}}}, doi = {{10.1515/crelle-2021-0063}}, volume = {{2022}}, year = {{2021}}, } @book{64262, author = {{Kusay-Merkle, Ursula}}, isbn = {{9783662628096}}, publisher = {{Springer Berlin Heidelberg}}, title = {{{Agiles Projektmanagement im Berufsalltag}}}, doi = {{10.1007/978-3-662-62810-2}}, year = {{2021}}, } @inproceedings{21178, abstract = {{When engaging in argumentative discourse, skilled human debaters tailor claims to the beliefs of the audience, to construct effective arguments. Recently, the field of computational argumentation witnessed extensive effort to address the automatic generation of arguments. However, existing approaches do not perform any audience-specific adaptation. In this work, we aim to bridge this gap by studying the task of belief-based claim generation: Given a controversial topic and a set of beliefs, generate an argumentative claim tailored to the beliefs. To tackle this task, we model the people's prior beliefs through their stances on controversial topics and extend state-of-the-art text generation models to generate claims conditioned on the beliefs. Our automatic evaluation confirms the ability of our approach to adapt claims to a set of given beliefs. In a manual study, we additionally evaluate the generated claims in terms of informativeness and their likelihood to be uttered by someone with a respective belief. Our results reveal the limitations of modeling users' beliefs based on their stances, but demonstrate the potential of encoding beliefs into argumentative texts, laying the ground for future exploration of audience reach.}}, author = {{Alshomary, Milad and Chen, Wei-Fan and Gurcke, Timon and Wachsmuth, Henning}}, booktitle = {{Proceedings of the 16th Conference of the European Chapter of the Association for Computational Linguistics: Main Volume}}, location = {{Online}}, pages = {{224--233}}, publisher = {{Association for Computational Linguistics}}, title = {{{Belief-based Generation of Argumentative Claims}}}, doi = {{10.18653/v1/2021.eacl-main.17}}, year = {{2021}}, } @misc{45855, author = {{Asenkerschbaumer, Stefan and Buhl, Hans-Ulrich and Sureth-Sloane, Caren and Weißenberger, Barbara E.}}, booktitle = {{Frankfurter Allgemeine Zeitung}}, number = {{101}}, pages = {{20}}, title = {{{Georg Giersberg: die Stimme für die BWL}}}, year = {{2021}}, } @inproceedings{41883, author = {{Lettner, Thomas and Gyger, Samuel and Zeuner, Katharina D. and Schweickert, Lucas and Steinhauer, Stephan and Reuterskiöld Hedlund, Carl and Stroj, Sandra and Rastelli, Armando and Hammar, Mattias and Trotta, Rinaldo and Jöns, Klaus D. and Zwiller, Val}}, number = {{24}}, pages = {{10501--10506}}, title = {{{Strain-Controlled Quantum Dot Fine Structure for Entangled Photon Generation at 1550 nm}}}, doi = {{10.1021/acs.nanolett.1c04024}}, volume = {{21}}, year = {{2021}}, } @inproceedings{59780, author = {{Petrov, Dmitry and Taron, Kim-Florian and Hilleringmann, Ulrich and Joubert, Trudi-Heleen}}, booktitle = {{2021 Smart Systems Integration (SSI)}}, publisher = {{IEEE}}, title = {{{Low-cost Sensor System for on-the-field Water Quality Analysis}}}, doi = {{10.1109/ssi52265.2021.9466956}}, year = {{2021}}, } @inproceedings{59777, author = {{Hilleringmann, Ulrich and Petrov, Dmitry and Mwammenywa, Ibrahim and Kagarura, Geoffrey Mark}}, booktitle = {{2021 IEEE AFRICON}}, publisher = {{IEEE}}, title = {{{Local Power Control using Wireless Sensor System for Microgrids in Africa}}}, doi = {{10.1109/africon51333.2021.9570970}}, year = {{2021}}, } @inproceedings{39397, author = {{Petrov, Dmitry and Kroschewski, Konstantin and Hilleringmann, Ulrich}}, booktitle = {{2021 Smart Systems Integration (SSI)}}, publisher = {{IEEE}}, title = {{{Microcontroller Firmware Design for Industrial Wireless Sensors}}}, doi = {{10.1109/ssi52265.2021.9467010}}, year = {{2021}}, } @article{59779, author = {{Petrov, Dmitry and Hilleringmann, Ulrich}}, issn = {{2415-6698}}, journal = {{Advances in Science, Technology and Engineering Systems Journal}}, number = {{5}}, pages = {{267--272}}, publisher = {{ASTES Journal}}, title = {{{Low-Power Primary Cell with Water-Based Electrolyte for Powering of Wireless Sensors}}}, doi = {{10.25046/aj060529}}, volume = {{6}}, year = {{2021}}, } @inproceedings{59774, author = {{Petrov, Dmitry and Kroschewski, Konstantin and Mwammenywa, Ibrahim and Kagarura, Geoffrey Mark and Hilleringmann, Ulrich}}, booktitle = {{2021 IEEE Sensors}}, publisher = {{IEEE}}, title = {{{Low-Cost NB-IoT Microgrid Power Quality Monitoring System}}}, doi = {{10.1109/sensors47087.2021.9639641}}, year = {{2021}}, } @phdthesis{64765, author = {{Nikitin, Natalie}}, title = {{{Regularity properties of infinite-dimensional Lie groups and exponential laws}}}, year = {{2021}}, }