Synthesis and Recognition Properties of Higher Order Tetrathiafulvalene (Ttf) Calix N Pyrroles (N=4-6)

Two new benzoTTF-annulated calix[n]pyrroles (n = 5 and 6) were synthesized via a one-step acid catalyzed condensation reaction and fully characterized via single crystallographic analyses. As compared to the known tetra-TTF annulated calix[4]pyrrole, which is also produced under the conditions of the condensation reaction, the expanded calix[n]pyrroles (n = 5 and 6) are characterized by a larger cavity size and a higher number of TTF units (albeit the same empirical formula). Analysis of the binding isotherms obtained from UV-Vis spectroscopic titrations carried out in CHCl3 in the presence of both anionic (Cl-, Br-, I-, CH3COO-, H2PO4-, and HSO4-) and neutral (1,3,5-trinitrobenzene (TNB) and 2,4,6-trinitrotoluene (TNT)) substrates revealed that as a general rule the calix[6]pyrrole derivative proved to be the most efficient molecular receptor for anions, while the calix[4]pyrrole congener proves most effective for the recognition of TNB and TNT. These findings are rationalized in terms of the number of electron rich TTF subunits and NH hydrogen bond donor groups within the series, as well as an ability to adopt conformations suitable for substrate recognition, and are supported by solid state structural analyses.National Science Foundation CHE 1057904, 0741973Robert A. Welch Foundation F-1018Danish Natural Science Research Council (FNU) 272-08-0047, 11-106744WCU (World Class University) program of Korea R32-2010-10217-0Villum FoundationChemistr

Electron transport in a two-terminal Aharonov-Bohm ring with impurities

Electron transport in a two-terminal Aharonov-Bohm ring with a few short-range scatterers is investigated. An analytical expression for the conductance as a function of the electron Fermi energy and magnetic flux is obtained using the zero-range potential theory. The dependence of the conductance on positions of scatterers is studied. We have found that the conductance exhibits asymmetric Fano resonances at certain energies. The dependence of the Fano resonances on magnetic field and positions of impurities is investigated. It is found that collapse of the Fano resonances occurs and discrete energy levels in the continuous spectrum appear at certain conditions. An explicit form for the wave function corresponding to the discrete level is obtained.Comment: 25 pages (one-column), 8 figure

MoS2-HgTe Quantum Dot Hybrid Photodetectors beyond 2 μm

Mercury telluride (HgTe) colloidal quantum dots (CQDs) have been developed as promising materials for the short and mid-wave infrared photodetection applications because of their low cost, solution processing and size tunable absorption in the short wave- and mid- infrared spectrum. However, the lowmobility and poor photo-gain have limited the responsivity of HgTe CQDs-based photodetectors to only tens of mA/W. Here, we integrated HgTe CQDs on a TiO2 encapsulated MoS2 transistor channel to form hybrid phototransistors with high responsivity of ~106 A/W, the highest reported to date for HgTe QDs. By operating the phototransistor in the depletion regime enabled by the gate modulated current of MoS2, the noise current is significantly suppressed leading to an experimentally measured specific detectivity D* of ~1012 Jones at a wavelength of 2 μm. This work demonstrates for the first time the potential of the hybrid 2D/QD detector technology in reaching out to wavelengths beyond 2 μm with compelling sensitivity.Peer ReviewedPostprint (author's final draft

Armut erzählen: Biografische Selbstrepräsentationen von Menschen in Armutslagen

Aktuelle Prognosen der zunehmenden Armut, die vielfältigen Lebenslagen in Armut und das homogene Bild von „Armen“ nimmt der Beitrag zum Anlass, um mit dem Konzept immersiver Macht (Mühlhoff 2018) aus einer affekttheoretischen Brille auf biografische Erzählungen von in Armut lebenden Person zu blicken und deren Schilderungen in den Kontext aktueller gesellschaftlicher und sozialarbeiterischer Herausforderungen zu stellen. Entlang des biografischen Interviews von Erika F., die an der Studie „Armut in Schleswig-Holstein“ teilnahm, entfaltet der Beitrag Zustände der emotionalen Überforderung wie auch (affektive) Bewältigungsmechanismen, mit der finanziellen Lage zurechtzukommen. Zudem fragt der Beitrag danach, in welchem Verhältnis gefühlte (Selbst-)Wahrnehmung, gesellschaftliche Zuschreibung und materiellen Grundlagen stehen und führt damit biografische Forschung, Armutsforschung und affekttheoretische Überlegungen zusammen

ProofBuddy: A Proof Assistant for Learning and Monitoring

Proof competence, i.e. the ability to write and check (mathematical) proofs, is an important skill in Computer Science, but for many students it represents a difficult challenge. The main issues are the correct use of formal language and the ascertainment of whether proofs, especially the students' own, are complete and correct. Many authors have suggested using proof assistants to assist in teaching proof competence, but the efficacy of the approach is unclear. To improve the state of affairs, we introduce ProofBuddy: a web-based tool using the Isabelle proof assistant which enables researchers to conduct studies of the efficacy of approaches to using proof assistants in education by collecting fine-grained data about the way students interact with proof assistants. We have performed a preliminary usability study of ProofBuddy at the Technical University of Denmark.Comment: In Proceedings TFPIE 2023, arXiv:2308.0611

Online-Lernen im Schülerlabor: Der Online-Workshop „Evolution von Coronaviren“

Das Schülerlabor teutolab-biotechnologie hat in Zeiten der Covid-19-Pandemie ein umfassendes Online-Angebot entwickelt. Der Online-Kurs „Evolution von Coronaviren“ richtet sich an Q2-Biologiekurse der gymnasialen Oberstufe. Er behandelt genetische Untersuchungen (Analyse von Genmutationen), phylogenetische Untersuchungen (Erstellung von Stammbäumen) sowie die Diagnostik von SARS-CoV-2 und wird von Mitarbeiter*innen des teutolab-biotechnologie via Zoom durchgeführt.

Establishment, characterization and functional testing of two novel ex vivo extraskeletal myxoid chondrosarcoma (EMC) cell models

Extraskeletal myxoid chondrosarcoma (EMC) is a malignant mesenchymal neoplasm of uncertain differentiation as classified by the WHO Classification of Tumours 2020. Although often associated with pronlonged survival, EMC has high rates of distant recurrences and disease-associated death. EMCs are translocation sarcomas and harbor in > 90% of the cases an NR4A3 rearrangement. The molecular consequences of the NR4A3 gene fusions are not yet fully elucidated as well-characterized ex vivo cell models for EMC are lacking. Patient-derived ex vivo models are important and essential tools for investigating disease mechanisms associated with diseases that are rare, that exhibit poor prognosis and for the identification of potential novel treatment options. We established two novel EMC ex vivo models (USZ20-EMC1 and USZ22-EMC2) for functional testing and research purposes. USZ20-EMC1 and USZ22-EMC2 were established and maintained as sarco-sphere cell models for several months in culture. The cells were molecularly characterized using DNA sequencing and methylation profiling. Both cell models represent their native tumor tissue as confirmed by histomorphology and their molecular profiles, suggesting that native tumor cell function can be recapitulated in the ex vivo models. Using a functional screening approach, novel anti-cancer drug sensitivities including potential synergistic combinations were identified. In conclusion, two novel EMC ex vivo cell models (USZ20-EMC1 and USZ22-EMC2) were successfully established and characterized from native tumor tissues. Both cell models will be useful tools for further investigating disease mechanisms and for answering basic and translational research questions. Keywords: Ex vivo cell model; Extraskeletal myxoid chondrosarcoma; Functional testing; Molecular profiling; Sarco-spher