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- ItemImpacts of meeting minimum access on critical earth systems amidst the Great Inequality(London : Springer Nature, 2022) Rammelt, Crelis F.; Gupta, Joyeeta; Liverman, Diana; Scholtens, Joeri; Ciobanu, Daniel; Abrams, Jesse F.; Bai, Xuemei; Gifford, Lauren; Gordon, Christopher; Hurlbert, Margot; Inoue, Cristina Y. A.; Jacobson, Lisa; Lade, Steven J.; Lenton, Timothy M.; McKay, David I. Armstrong; Nakicenovic, Nebojsa; Okereke, Chukwumerije; Otto, Ilona M.; Pereira, Laura M.; Prodani, Klaudia; Rockström, Johan; Stewart-Koster, Ben; Verburg, Peter H.; Zimm, CarolineThe Sustainable Development Goals aim to improve access to resources and services, reduce environmental degradation, eradicate poverty and reduce inequality. However, the magnitude of the environmental burden that would arise from meeting the needs of the poorest is under debate—especially when compared to much larger burdens from the rich. We show that the ‘Great Acceleration’ of human impacts was characterized by a ‘Great Inequality’ in using and damaging the environment. We then operationalize ‘just access’ to minimum energy, water, food and infrastructure. We show that achieving just access in 2018, with existing inequalities, technologies and behaviours, would have produced 2–26% additional impacts on the Earth’s natural systems of climate, water, land and nutrients—thus further crossing planetary boundaries. These hypothetical impacts, caused by about a third of humanity, equalled those caused by the wealthiest 1–4%. Technological and behavioural changes thus far, while important, did not deliver just access within a stable Earth system. Achieving these goals therefore calls for a radical redistribution of resources.
- ItemQuantum critical fluctuations in an Fe-based superconductor(London : Springer Nature, 2022) Jost, Daniel; Peis, Leander; He, Ge; Baum, Andreas; Geprägs, Stephan; Palmstrom, Johanna C.; Ikeda, Matthias S.; Fisher, Ian R.; Wolf, Thomas; Lederer, Samuel; Kivelson, Steven A.; Hackl, RudiQuantum critical fluctuations may prove to play an instrumental role in the formation of unconventional superconductivity. Here, we show that the characteristic scaling of a marginal Fermi liquid is present in inelastic light scattering data of an Fe-based superconductor tuned through a quantum critical point (QCP) by chemical substitution or doping. From the doping dependence of the imaginary time dynamics we are able to distinguish regions dominated by quantum critical behavior from those having classical critical responses. This dichotomy reveals a connection between the marginal Fermi liquid behavior and quantum criticality. In particular, the overlap between regions of high superconducting transition temperatures and quantum critical scaling suggests a contribution from quantum fluctuations to the formation of superconductivity.
- ItemCopper/iron co-catalyzed alkoxycarbonylation of unactivated alkyl bromides(London : Springer Nature, 2018) Li, Y.; Wu, X.-F.Carbonylative transformations of alkyl bromides have been explored less than those of aryl halides, in part because of the high barrier to activation of aryl bromides. Additionally, alkyl-metal reagents formed in situ can tend to undergo β-hydride elimination. Here we describe a copper/iron co-catalyzed alkoxycarbonylation of unactivated alkyl bromides. In the presence of catalytic quantities of iron and copper catalysts, primary, secondary, and tertiary alkyl bromides are carbonylatively transformed into the corresponding aliphatic esters in good yields. A potential reaction mechanism is proposed based on control experiments.
- ItemConsensus model of a cyanobacterial light-dependent protochlorophyllide oxidoreductase in its pigment-free apo-form and photoactive ternary complex(London : Springer Nature, 2019) Schneidewind, Judith; Krause, Frank; Bocola, Marco; Stadler, Andreas Maximilian; Davari, Mehdi D.; Schwaneberg, Ulrich; Jaeger, Karl-Erich; Krauss, UlrichPhotosynthetic organisms employ two different enzymes for the reduction of the C17 = C18 double bond of protochlorophyllide (Pchlide), yielding the chlorophyll precursor chlorophyllide. First, a nitrogenase-like, light-independent (dark-operative) Pchlide oxidoreductase and secondly, a light-dependent Pchlide oxidoreductase (LPOR). For the latter enzyme, despite decades of research, no structural information is available. Here, we use protein structure modelling, molecular dynamics (MD) simulations combined with multi-wavelength analytical ultracentrifugation (MWA-AUC) and small angle X-ray scattering (SAXS) experiments to derive a consensus model of the LPOR apoprotein and the substrate/cofactor/LPOR ternary complex. MWA-AUC and SAXS experiments independently demonstrate that the apoprotein is monomeric, while ternary complex formation induces dimerization. SAXS-guided modelling studies provide a full-length model of the apoprotein and suggest a tentative mode of dimerization for the LPOR ternary complex, supported by published cross-link constraints. Our study provides a first impression of the LPOR structural organization.
- ItemAll-optical supercontinuum switching(London : Springer Nature, 2020) Melchert, Oliver; Brée, Carsten; Tajalli, Ayhan; Pape, Alexander; Arkhipov, Rostislav; Willms, Stephanie; Babushkin, Ihar; Skryabin, Dmitry; Steinmeyer, Günter; Morgner, Uwe; Demircan, AyhanEfficient all-optical switching is a challenging task as photons are bosons and cannot immediately interact with each other. Consequently, one has to resort to nonlinear optical interactions, with the Kerr gate being the classical example. However, the latter requires strong pulses to switch weaker ones. Numerous approaches have been investigated to overcome the resulting lack of fan-out capability of all-optical switches, most of which relied on types of resonant enhancement of light-matter interaction. Here we experimentally demonstrate a novel approach that utilizes switching between different portions of soliton fission induced supercontinua, exploiting an optical event horizon. This concept enables a high switching efficiency and contrast in a dissipation free setting. Our approach enables fan-out, does not require critical biasing, and is at least partially cascadable. Controlling complex soliton dynamics paves the way towards building all-optical logic gates with advanced functionalities. © 2020, The Author(s).
- ItemNucleation of jet engine oil vapours is a large source of aviation-related ultrafine particles(London : Springer Nature, 2022) Ungeheuer, Florian; Caudillo, LucÃa; Ditas, Florian; Simon, Mario; van Pinxteren, Dominik; Kılıç, DoÄŸuÅŸhan; Rose, Diana; Jacobi, Stefan; Kürten, Andreas; Curtius, Joachim; Vogel, Alexander L.Large airports are a major source of ultrafine particles, which spread across densely populated residential areas, affecting air quality and human health. Jet engine lubrication oils are detectable in aviation-related ultrafine particles, however, their role in particle formation and growth remains unclear. Here we show the volatility and new-particle-formation ability of a common synthetic jet oil, and the quantified oil fraction in ambient ultrafine particles downwind of Frankfurt International Airport, Germany. We find that the oil mass fraction is largest in the smallest particles (10-18 nm) with 21% on average. Combining ambient particle-phase concentration and volatility of the jet oil compounds, we determine a lower-limit saturation ratio larger than 1 × 105 for ultra-low volatility organic compounds. This indicates that the oil is an efficient nucleation agent. Our results demonstrate that jet oil nucleation is an important mechanism that can explain the abundant observations of high number concentrations of non-refractory ultrafine particles near airports.
- ItemGlobal perturbation of stratospheric water and aerosol burden by Hunga eruption(London : Springer Nature, 2022) Khaykin, Sergey; Podglajen, Aurelien; Ploeger, Felix; Grooß, Jens-Uwe; Tence, Florent; Bekki, Slimane; Khlopenkov, Konstantin; Bedka, Kristopher; Rieger, Landon; Baron, Alexandre; Godin-Beekmann, Sophie; Legras, Bernard; Sellitto, Pasquale; Sakai, Tetsu; Barnes, John; Uchino, Osamu; Morino, Isamu; Nagai, Tomohiro; Wing, Robin; Baumgarten, Gerd; Gerding, Michael; Duflot, Valentin; Payen, Guillaume; Jumelet, Julien; Querel, Richard; Liley, Ben; Bourassa, Adam; Clouser, Benjamin; Feofilov, Artem; Hauchecorne, Alain; Ravetta, FrançoisThe eruption of the submarine Hunga volcano in January 2022 was associated with a powerful blast that injected volcanic material to altitudes up to 58 km. From a combination of various types of satellite and ground-based observations supported by transport modeling, we show evidence for an unprecedented increase in the global stratospheric water mass by 13% relative to climatological levels, and a 5-fold increase of stratospheric aerosol load, the highest in the last three decades. Owing to the extreme injection altitude, the volcanic plume circumnavigated the Earth in only 1 week and dispersed nearly pole-to-pole in three months. The unique nature and magnitude of the global stratospheric perturbation by the Hunga eruption ranks it among the most remarkable climatic events in the modern observation era, with a range of potential long-lasting repercussions for stratospheric composition and climate.
- ItemNickel-catalysed carbonylative homologation of aryl iodides(London : Springer Nature, 2018) Peng, J.-B.; Wu, F.-P.; Qi, X.; Ying, J.; Wu, X.-F.Homologation is an important organic transformation which extends the carbon chain of a parent molecule, and many procedures have been established. However, although carbonylation reactions are now well developed as valuable methods for the synthesis of carbonyl-containing compounds, studies of carbonylative homologation are limited. Here we report a nickel-catalysed carbonylative homologation of aryl iodides. With molybdenum hexacarbonyl as the solid carbon monoxide source and silane as the deoxygenation reagent, benzylic units can be effectively produced. Various (hetero)arenes can be successfully benzylated and give the corresponding products in moderate to excellent yields.
- ItemMagnetization-driven Lifshitz transition and charge-spin coupling in the kagome metal YMn6Sn6(London : Springer Nature, 2022) Siegfried, Peter E.; Bhandari, Hari; Jones, David C.; Ghimire, Madhav P.; Dally, Rebecca L.; Poudel, Lekh; Bleuel, Markus; Lynn, Jeffrey W.; Mazin, Igor I.; Ghimire, Nirmal J.The Fermi surface (FS) is essential for understanding the properties of metals. It can change under both conventional symmetry-breaking phase transitions and Lifshitz transitions (LTs), where the FS, but not the crystal symmetry, changes abruptly. Magnetic phase transitions involving uniformly rotating spin textures are conventional in nature, requiring strong spin-orbit coupling (SOC) to influence the FS topology and generate measurable properties. LTs driven by a continuously varying magnetization are rarely discussed. Here we present two such manifestations in the magnetotransport of the kagome magnet YMn6Sn6: one caused by changes in the magnetic structure and another by a magnetization-driven LT. The former yields a 10% magnetoresistance enhancement without a strong SOC, while the latter a 45% reduction in the resistivity. These phenomena offer a unique view into the interplay of magnetism and electronic topology, and for understanding the rare-earth counterparts, such as TbMn6Sn6, recently shown to harbor correlated topological physics.
- ItemStabilization mechanism of molecular orbital crystals in IrTe2(London : Springer Nature, 2022) Ritschel, Tobias; Stahl, Quirin; Kusch, Maximilian; Trinckauf, Jan; Garbarino, Gaston; Svitlyk, Volodymyr; Mezouar, Mohamed; Yang, Junjie; Cheong, Sang-Wook; Geck, JochenDoped IrTe2 is considered a platform for topological superconductivity and therefore receives currently a lot of interest. In addition, the superconductivity in these materials exists in close vicinity to electronic order and the formation of molecular orbital crystals, which we explore here by means of high-pressure single crystal x-ray diffraction in combination with density functional theory. Our crystallographic refinements provide detailed information about the structural evolution as a function of applied pressure up to 42 GPa. Using this structural information for density functional theory calculations, we show that the local multicenter bonding in IrTe2 is driven by changes in the Ir-Te-Ir bond angle. When the electronic order sets in, this bond angle decreases drastically, leading to a stabilization of a multicenter molecular orbital bond. This unusual local mechanism of bond formation in an itinerant material provides a natural explanation for the different electronic orders in IrTe2. It further illustrates the strong coupling of the electrons with the lattice and is most likely relevant for the superconductivity in this material.