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- ItemAuthor Correction: A combination of electrochemistry and mass spectrometry to monitor the interaction of reactive species with supported lipid bilayers (Scientific Reports, (2020), 10, 1, (18683), 10.1038/s41598-020-75514-7)(London : Nature Publishing Group, 2021) Ravandeh, M.; Kahlert, H.; Jablonowski, H.; Lackmann, J.-W.; Striesow, J.; Agmo Hernández, V.; Wende, K.Correction to: Scientific Reports https://doi.org/10.1038/s41598-020-75514-7, published online 29 October 2020
- ItemPhase-enabled metal-organic framework homojunction for highly selective CO2 photoreduction(London : Nature Publishing Group, 2021) Liu, Yannan; Chen, Chuanshuang; Valdez, Jesus; Meira, Debora Motta; He, Wanting; Wang, Yong; Harnagea, Catalin; Lu, Qiongquiong; Guner, Tugrul; Wang, Hao; Liu, Cheng-Hao; Zhang, Qingzhe; Huang, Shengyun; Yurtsever, Aycan; Chaker, Mohamed; Ma, DonglingConversion of clean solar energy to chemical fuels is one of the promising and up-and-coming applications of metal–organic frameworks. However, fast recombination of photogenerated charge carriers in these frameworks remains the most significant limitation for their photocatalytic application. Although the construction of homojunctions is a promising solution, it remains very challenging to synthesize them. Herein, we report a well-defined hierarchical homojunction based on metal–organic frameworks via a facile one-pot synthesis route directed by hollow transition metal nanoparticles. The homojunction is enabled by two concentric stacked nanoplates with slightly different crystal phases. The enhanced charge separation in the homojunction was visualized by in-situ surface photovoltage microscopy. Moreover, the as-prepared nanostacks displayed a visible-light-driven carbon dioxide reduction with very high carbon monooxide selectivity, and excellent stability. Our work provides a powerful platform to synthesize capable metal–organic framework complexes and sheds light on the hierarchical structure-function relationships of metal–organic frameworks.
- ItemImproved kinetic behaviour of Mg(NH2)2-2LiH doped with nanostructured K-modified-LixTiyOz for hydrogen storage(London : Nature Publishing Group, 2020) Gizer, G.; Puszkiel, J.; Riglos, M.V.C.; Pistidda, C.; Ramallo-López, J.M.; Mizrahi, M.; Santoru, A.; Gemming, T.; Tseng, J.-C.; Klassen, T.; Dornheim, M.The system Mg(NH2)2 + 2LiH is considered as an interesting solid-state hydrogen storage material owing to its low thermodynamic stability of ca. 40 kJ/mol H2 and high gravimetric hydrogen capacity of 5.6 wt.%. However, high kinetic barriers lead to slow absorption/desorption rates even at relatively high temperatures (>180 °C). In this work, we investigate the effects of the addition of K-modified LixTiyOz on the absorption/desorption behaviour of the Mg(NH2)2 + 2LiH system. In comparison with the pristine Mg(NH2)2 + 2LiH, the system containing a tiny amount of nanostructured K-modified LixTiyOz shows enhanced absorption/desorption behaviour. The doped material presents a sensibly reduced (∼30 °C) desorption onset temperature, notably shorter hydrogen absorption/desorption times and reversible hydrogen capacity of about 3 wt.% H2 upon cycling. Studies on the absorption/desorption processes and micro/nanostructural characterizations of the Mg(NH2)2 + 2LiH + K-modified LixTiyOz system hint to the fact that the presence of in situ formed nanostructure K2TiO3 is the main responsible for the observed improved kinetic behaviour.
- ItemPublisher Correction: Rapid and low-cost insect detection for analysing species trapped on yellow sticky traps(London : Nature Publishing Group, 2021) Böckmann, Elias; Pfaff, Alexander; Schirrmann, Michael; Pflanz, MichaelCorrection to: Scientific Reports https://doi.org/10.1038/s41598-021-89930-w, published online 17 May 2021
- ItemCoherent interaction of atoms with a beam of light confined in a light cage(London : Nature Publishing Group, 2021) Davidson-Marquis, Flavie; Gargiulo, Julian; Gómez-López, Esteban; Jang, Bumjoon; Kroh, Tim; Müller, Chris; Ziegler, Mario; Maier, Stefan A.; Kübler, Harald; Schmidt, Markus A.; Benson, OliverControlling coherent interaction between optical fields and quantum systems in scalable, integrated platforms is essential for quantum technologies. Miniaturised, warm alkali-vapour cells integrated with on-chip photonic devices represent an attractive system, in particular for delay or storage of a single-photon quantum state. Hollow-core fibres or planar waveguides are widely used to confine light over long distances enhancing light-matter interaction in atomic-vapour cells. However, they suffer from inefficient filling times, enhanced dephasing for atoms near the surfaces, and limited light-matter overlap. We report here on the observation of modified electromagnetically induced transparency for a non-diffractive beam of light in an on-chip, laterally-accessible hollow-core light cage. Atomic layer deposition of an alumina nanofilm onto the light-cage structure was utilised to precisely tune the high-transmission spectral region of the light-cage mode to the operation wavelength of the atomic transition, while additionally protecting the polymer against the corrosive alkali vapour. The experiments show strong, coherent light-matter coupling over lengths substantially exceeding the Rayleigh range. Additionally, the stable non-degrading performance and extreme versatility of the light cage provide an excellent basis for a manifold of quantum-storage and quantum-nonlinear applications, highlighting it as a compelling candidate for all-on-chip, integrable, low-cost, vapour-based photon delay.
- ItemExperimental proof of Joule heating-induced switched-back regions in OLEDs(London : Nature Publishing Group, 2020) Kirch, Anton; Fische, Axel; Liero, Matthias; Fuhrmann, Jürgen; Glitzky, Annegret; Reineke, SebastianOrganic light-emitting diodes (OLEDs) have become a major pixel technology in the display sector, with products spanning the entire range of current panel sizes. The ability to freely scale the active area to large and random surfaces paired with flexible substrates provides additional application scenarios for OLEDs in the general lighting, automotive, and signage sectors. These applications require higher brightness and, thus, current density operation compared to the specifications needed for general displays. As extended transparent electrodes pose a significant ohmic resistance, OLEDs suffering from Joule self-heating exhibit spatial inhomogeneities in electrical potential, current density, and hence luminance. In this article, we provide experimental proof of the theoretical prediction that OLEDs will display regions of decreasing luminance with increasing driving current. With a two-dimensional OLED model, we can conclude that these regions are switched back locally in voltage as well as current due to insufficient lateral thermal coupling. Experimentally, we demonstrate this effect in lab-scale devices and derive that it becomes more severe with increasing pixel size, which implies its significance for large-area, high-brightness use cases of OLEDs. Equally, these non-linear switching effects cannot be ignored with respect to the long-term operation and stability of OLEDs; in particular, they might be important for the understanding of sudden-death scenarios. © 2020, The Author(s).
- ItemThe SciQA Scientific Question Answering Benchmark for Scholarly Knowledge(London : Nature Publishing Group, 2023) Auer, Sören; Barone, Dante A.C.; Bartz, Cassiano; Cortes, Eduardo G.; Jaradeh, Mohamad Yaser; Karras, Oliver; Koubarakis, Manolis; Mouromtsev, Dmitry; Pliukhin, Dmitrii; Radyush, Daniil; Shilin, Ivan; Stocker, Markus; Tsalapati, EleniKnowledge graphs have gained increasing popularity in the last decade in science and technology. However, knowledge graphs are currently relatively simple to moderate semantic structures that are mainly a collection of factual statements. Question answering (QA) benchmarks and systems were so far mainly geared towards encyclopedic knowledge graphs such as DBpedia and Wikidata. We present SciQA a scientific QA benchmark for scholarly knowledge. The benchmark leverages the Open Research Knowledge Graph (ORKG) which includes almost 170,000 resources describing research contributions of almost 15,000 scholarly articles from 709 research fields. Following a bottom-up methodology, we first manually developed a set of 100 complex questions that can be answered using this knowledge graph. Furthermore, we devised eight question templates with which we automatically generated further 2465 questions, that can also be answered with the ORKG. The questions cover a range of research fields and question types and are translated into corresponding SPARQL queries over the ORKG. Based on two preliminary evaluations, we show that the resulting SciQA benchmark represents a challenging task for next-generation QA systems. This task is part of the open competitions at the 22nd International Semantic Web Conference 2023 as the Scholarly Question Answering over Linked Data (QALD) Challenge.
- ItemTunneling current modulation in atomically precise graphene nanoribbon heterojunctions(London : Nature Publishing Group, 2021) Senkovskiy, B.; Nenashev, A.; Alavi, S.; Falke, Y.; Hell, M.; Bampoulis, P.; Rybkovskiy, D.; Usachov, D.; Fedorov, A.; Chernov, A.; Gebhard, F.; Meerholz, K.; Hertel, D.; Arita, M.; Okuda, T.; Miyamoto, K.; Shimada, K.; Fischer, F.; Michely, T.; Baranovskii, S.; Lindfors, K.; Szkopek, T.; Grüneis, A.Lateral heterojunctions of atomically precise graphene nanoribbons (GNRs) hold promise for applications in nanotechnology, yet their charge transport and most of the spectroscopic properties have not been investigated. Here, we synthesize a monolayer of multiple aligned heterojunctions consisting of quasi-metallic and wide-bandgap GNRs, and report characterization by scanning tunneling microscopy, angle-resolved photoemission, Raman spectroscopy, and charge transport. Comprehensive transport measurements as a function of bias and gate voltages, channel length, and temperature reveal that charge transport is dictated by tunneling through the potential barriers formed by wide-bandgap GNR segments. The current-voltage characteristics are in agreement with calculations of tunneling conductance through asymmetric barriers. We fabricate a GNR heterojunctions based sensor and demonstrate greatly improved sensitivity to adsorbates compared to graphene based sensors. This is achieved via modulation of the GNR heterojunction tunneling barriers by adsorbates.
- ItemMultiple fermion scattering in the weakly coupled spin-chain compound YbAlO3(London : Nature Publishing Group, 2021) Nikitin, S.; Nishimoto, S.; Fan, Y.; Wu, J.; Wu, L.; Sukhanov, A.; Brando, M.; Pavlovskii, N.; Xu, J.; Vasylechko, L.; Yu, R.; Podlesnyak, A.The Heisenberg antiferromagnetic spin-1/2 chain, originally introduced almost a century ago, is one of the best studied models in quantum mechanics due to its exact solution, but nevertheless it continues to present new discoveries. Its low-energy physics is described by the Tomonaga-Luttinger liquid of spinless fermions, similar to the conduction electrons in one-dimensional metals. In this work we investigate the Heisenberg spin-chain compound YbAlO3 and show that the weak interchain coupling causes Umklapp scattering between the left- and right-moving fermions and stabilizes an incommensurate spin-density wave order at q = 2kF under finite magnetic fields. These Umklapp processes open a route to multiple coherent scattering of fermions, which results in the formation of satellites at integer multiples of the incommensurate fundamental wavevector Q = nq. Our work provides surprising and profound insight into bandstructure control for emergent fermions in quantum materials, and shows how neutron diffraction can be applied to investigate the phenomenon of coherent multiple scattering in metals through the proxy of quantum magnetic systems.
- ItemTumor cytotoxicity and immunogenicity of a novel V-jet neon plasma source compared to the kINPen(London : Nature Publishing Group, 2021) Miebach, Lea; Freund, Eric; Horn, Stefan; Niessner, Felix; Sagwal, Sanjeev Kumar; von Woedtke, Thomas; Emmert, Steffen; Weltmann, Klaus-Dieter; Clemen, Ramona; Schmidt, Anke; Gerling, Torsten; Bekeschus, SanderRecent research indicated the potential of cold physical plasma in cancer therapy. The plethora of plasma-derived reactive oxygen and nitrogen species (ROS/RNS) mediate diverse antitumor effects after eliciting oxidative stress in cancer cells. We aimed at exploiting this principle using a newly designed dual-jet neon plasma source (Vjet) to treat colorectal cancer cells. A treatment time-dependent ROS/RNS generation induced oxidation, growth retardation, and cell death within 3D tumor spheroids were found. In TUM-CAM, a semi in vivo model, the Vjet markedly reduced vascularized tumors' growth, but an increase of tumor cell immunogenicity or uptake by dendritic cells was not observed. By comparison, the argon-driven single jet kINPen, known to mediate anticancer effects in vitro, in vivo, and in patients, generated less ROS/RNS and terminal cell death in spheroids. In the TUM-CAM model, however, the kINPen was equivalently effective and induced a stronger expression of immunogenic cancer cell death (ICD) markers, leading to increased phagocytosis of kINPen but not Vjet plasma-treated tumor cells by dendritic cells. Moreover, the Vjet was characterized according to the requirements of the DIN-SPEC 91315. Our results highlight the plasma device-specific action on cancer cells for evaluating optimal discharges for plasma cancer treatment.