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First-Principles Investigation of Adsorption of Ethene on a Twice Oxidized NiF2 (001) Surface: A Model for the Simons Process
No full textElectrochemical fluorination on a nickel anode (Simons process) is an important process for producing fluorinated compounds. Despite its success, the mechanism is still under debate. Here a first-principles study is presented of fluorination of ethene on a model fluorinated (001) NiFmathematical equation surface, which is chosen because it is stabilized under the external potential close to that at which the Simons cell operates and because it has a readily available mathematical equation unit providing fluorine source to aid fluorination reactions. The adsorption of the simplest double bond containing hydrocarbon on this surface is investigated. It is placed on the surface in different orientation, leading to six distinct structural outcomes upon relaxation. These include formation of 1,2-difluoroethane, fluoroethene, and 1,2-difluoroethene, alongside other fluorinated products as well as monocarbon fragments. This is one of the first computational studies of the catalytic Simons-type fluorination and can, despite its simplicity, offers some insight into reaction pathways and surface interactions
Behavior change and infection induced immunity led to the decline of the 2022 Mpox outbreak in Berlin
No full textBackground
Mpox denotes a viral zoonosis caused by the Orthopoxvirus monkeypox (MPXV), which is endemic in West and Central Africa. In spring 2022, notable outbreaks of MPXV clade IIb were recorded in several high-income countries, predominantly affecting men who have sex with men (MSM). At the peak of the outbreak, over 200 new mpox cases per week were reported in Berlin, which constitutes one of the largest MSM population in Europe. Within the same year, the outbreak significantly declined, and it is unclear which factors contributed to this rapid decrease.
Methods
To investigate the concomitant effects of sexual contact networks, transient contact reductions and the effect of infection- vs. vaccine-derived immunity on the 2022 mpox outbreak, we calibrated an agent-based model with epidemic, vaccination, contact- and behavioral data.
Results
Our results indicate that vaccination has a marginal effect on the epidemic decline. Rather, a combination of infection-induced immunity of high-contact individuals, as well as transient behavior changes reduce the number of susceptible individuals below the epidemic threshold. However, the 2022 mpox vaccination campaign, together with infection-derived immunity may contribute to herd-immunity in the Berlin MSM population against ongoing clade I mpox outbreaks. Demographic changes and immune waning may deteriorate this herd immunity over time.
Conclusions
These findings highlight that, in addition to vaccination, timely and clear communication of transmission routes may trigger spontaneous protective behavior within key populations; underscoring the importance of targeted sexual health education as a core component of outbreak response
Do Natural Disasters Affect Household Saving? Evidence From the August 2002 Flood in Germany
No full textRecently, there is a growing interest in understanding how individuals adapt to changing climate conditions and climate-induced extreme weather events. An underexplored question is whether and how climate-related natural hazards affect household saving behavior. For this purpose, we exploit a natural experiment stemming from the European Flood of August 2002. Combining micro data with geo-coded flood maps allows us to analyze the causal impact of flood exposure on household savings within a difference-in-differences setting. We find that flood exposure depresses household saving behavior in the medium run. A likely explanation is moral hazard induced by massive government support for affected households
A sub-chondritic nickel stable isotope composition of Mars
No full textTo understand accretion and differentiation of Mars, we report high-precision mass-dependent Ni (siderophile and chalcophile) isotope data of 37 bulk Martian meteorites. Large δ60/58Ni variations observed among these Martian meteorites are attributed primarily to magmatism and Ni diffusion in zoned olivine and sulfide. Shergottites show systematically higher Mg# and lower δ60/58Ni values relative to nakhlites, which can be caused by olivine crystallization, consistent with the Ni isotope fractionation factor between olivine and melt. Two Ni-rich chassignites (Martian dunites) provide the best current estimate of the upper limit of δ60/58Ni of bulk silicate Mars (BSM): 0.110 ± 0.031 ‰, since olivine crystallization causes Ni isotope fractionation. Subtracting a presumably chondritic contribution by late accretion, the proto-BSM should possess a δ60/58Ni of ≤ 0.074 ‰ that is lower than the average of chondrites (∼0.24 ‰). This sub-chondritic value of Martian mantle suggests the sulfur-rich core formation has not caused Ni isotope fractionation, because the sulfide and Martian sulfur-rich core is believed to enrich in light Ni isotopes. Instead, Ni isotope differences between Earth, Mars, Vesta, and the ureilites can be inherited from non-bulk chondritic precursor materials
Graptolite biostratigraphy of the Dapingian GSSP and its global correlation
No full textThe graptolite fauna of the Dapingian Global Stratotype Section and Point (GSSP) at Huanghuachang is relatively poorly preserved and difficult to correlate with the graptolite record of other regions. A few tie points have been identified, indicating that the base of the Dapingian lies above the base of the regional Azygograptus suecicus Biozone of South China. The base of this graptolite zone, however, represents the first appearance datum (FAD) of the genus Azygograptus instead of the species, as the species Azygograptus suecicus is considerably younger. The Azygograptus suecicus Biozone can be correlated indirectly with Scandinavia through the presence of isograptids associated with Azygograptus specimens in Sweden and Norway. The correlation of the upper Dapingian is uncertain, even though the top of the Dawan Formation with Levisograptus austrodentatus at the base of the Darriwilian indicates a correlation of the upper Dapingian with the Australasian upper Castlemainian and Yapeenian
Leveraging mirror-image glycans in carbohydrate materials
No full textChirality has become a fundamental design principle to craft peptide materials. In contrast, the systematic exploitation of chirality to build glycan materials remains largely unexplored, despite the rich chiral diversity of carbohydrates, with both D- and L-configurations readily available in nature. Here, we emphasize the added value of exploring mirror-image glycans to tailor carbohydrate materials. By examining the distinctive chiral features of carbohydrates in comparison to peptides, we demonstrate how these characteristics provide powerful opportunities to modulate and elucidate the rules governing glycan assembly. We discuss examples of carbohydrate materials based on individual enantiomers, the co-assembly of racemic mixtures, and the assembly of heterochiral sequences. Each section is introduced with key insights from peptide materials, serving as inspiration and guidance for the future design of glycan assemblies
Steuerung der Kooperativität bei Spinübergängen von Molekülen in Kontakt mit Oberflächen
No full textThe possibility to switch between a high-spin (HS) and a low-spin (LS) state by external means makes spin-crossover (SCO) molecules highly interesting for a molecule-based spin electronics. Cooperativity in the spin transition is thereby one of the most important issues, since it can lead to bistability in the spin states. In order to obtain insight into the emergence of cooperative effects, a series of polynuclear iron(II) SCO complexes was prepared and investigated. In a first approach, dinuclear Fe(II) SCO complexes composed of two Fe(II)(bpz)2 moieties (bpz = dihydrobis(pyrazolyl)borate) bridged by bis(2,2´-bipyridine) ligands were characterized in the bulk form by magnetic susceptibility as well as Mössbauer, UV/vis, and X-ray absorption spectroscopy (XAS) measurements. Moreover, these complexes were deposited on surfaces by pulsed liquid injection and investigated as thin films by XAS. Applying THz spectroscopy to these systems, detailed information on their electronic and vibrational properties could be obtained. In particular, careful analysis of their far infrared (FIR) spectra provided evidence for a mixed HS-LS state being populated in the course of the thermal transition from HS-HS at room temperature to LS-LS at 4 K. Besides these studies on dimeric SCO complexes, three strategies for the synthesis of polymeric SCO compounds were followed that can also be applied to surfaces. These involve the bridging of Fe(II) complexes equatorially coordinated by N4 ligands through 4,4´-bipyridine molecules and the covalent coupling of Fe(II) SCO complexes supported by tridentate and tripodal ligands. To this end, ditopic ligands with tridentate, deprotonatable endgroups were developed that form SCO polymers upon mixing with Fe(II) salts. Moreover, ditopic ligands with tris(pyrazolyl)borate endgroups were prepared that also form SCO polymers in the presence of Fe(II) ions. As an alternative to the latter approach, pre-formed Fe(II) bis((trispyrazolyl)borate) complexes were polymerized via Sonogashira coupling and characterized structurally as well as spectroscopically.Die Möglichkeit, den Spinzustand von Spin-Crossover- (SCO)-Molekülen durch externe Parameter zwischen einem High-Spin- (HS) und einem Low-Spin- (LS)-Zustand zu schalten, ist von großem Interesse für eine zukünftige molekulare Spinelektronik. Von großer Wichtigkeit ist dabei die Kooperativität beim Spinschalten, da dadurch Bistabilität erreicht werden kann. Um Einblicke in die Entstehung kooperativer Effekte zu erhalten, wurde eine Serie polynuklearer Fe(II) SCO-Komplexe synthetisiert und untersucht. In einem ersten Ansatz wurden dinukleare Fe(II) SCO-Komplexe, die zwei Fe(II)(bpz)2 Einheiten (bpz = dihydrobis(pyrazolyl)bo-rate) enthalten, hergestellt und als Volumenmaterialien mit magnetischer Suszeptibilität sowie Mössbauer-, UV/vis- und Röntgenabsorptions-Spektroskopie (XAS) untersucht. Weiterhin wurden diese Komplexe mit Hilfe von Pulsed Liquid Injection auf Oberflächen deponiert und als dünne Filme mit XAS charakterisiert. Die Anwendung von THz-Spektroskopie auf diese Systeme lieferte detaillierte Informationen hinsichtlich ihrer elektronischen Struktur und ihrer Schwingungseigenschaften. Insbesondere gelang es durch sorgfältige Analyse ihrer Fern-Infrarot- (FIR)-Spektren, einen gemischten HS-LS-Zustand nachzuweisen, welcher im Lauf des thermischen Spinübergangs von HS-HS bei Raumtemperatur zu LS-LS bei 4 K populiert wird. Neben diesen Studien an dimeren SCO-Komplexen wurden drei Strategien für die Synthese polymerer SCO-Verbindungen verfolgt, welche auch auf Oberflächen anwendbar sind. Diese umfassen die Verbrückung von Fe(II) SCO-Komplexen, welche äquatorial durch planare N4-Liganden koordiniert sind, durch 4,4´-Bipyridin sowie die kovalente Verknüpfung von Fe(II) SCO-Komplexen, welche durch tridentate und tripodale Liganden koordiniert sind. Dazu wurden ditopische Liganden mit tridentaten, deprotonierbaren Endgruppen entwickelt, welche beim Zusammengeben mit Fe(II)-Salzen Polymere bilden. Weiterhin wurden ditopische Liganden mit Tris(pyrazolyl)borat-Endgruppen hergestellt, welche ebenfalls SCO-Polymere in der Gegenwart von Fe(II)-Ionen bilden. Zum Vergleich mit der letztgenannten Strategie wurden auch funktionalisierte Fe(II) bis(tris(pyrazolyl)borat)-Komplexe über Sonogashira-Kopplung polymerisiert und strukturell sowie spektroskopisch charakterisiert
Optimal Regularity of Area Maximizing Hypersurfaces in Minkowski Space
No full textIn 1982, Bartnik and Simon proved that area maximizing hypersurfaces are smooth, strictly spacelike and maximal (mean curvature zero) away from a singular set which consists of light rays connecting boundary points. Around the same time, Leon Simon conjectured that area maximizing hypersurfaces ought to be of class C^{1,1} across their singular set, and pointed out that, if correct, this regularity statement could not be improved to C^2 in view of a certain example. In this paper, we prove Leon Simon’s conjecture.1982 bewiesen Bartnik und Simon, dass flächenmaximierende Hyperflächen glatt, streng raumartig und maximal (mittlere Krümmung Null) sind, abgesehen von einer singulären Menge, die aus Lichtstrahlen besteht, die Randpunkte verbinden. Etwa zur gleichen Zeit stellte Leon Simon die Vermutung auf, dass flächenmaximierende Hyperflächen über ihre singuläre Menge hinweg der Klasse C^{1,1} angehören müssten, und wies darauf hin, dass diese Regularitätsaussage angesichts eines bestimmten Beispiels nicht auf C^2 verbessert werden könne, sollte sie zutreffen. In diesem Artikel beweisen wir Leon Simons Vermutung
Schrödinger’s off-balance-sheet fiscal agency: the Recovery and Resilience Facility and the limits to incremental fiscal integration in Europe
No full textThe Recovery and Resilience Facility (RRF), introduced as the EU’s main macro-financial response to the COVID-19 pandemic, is an off-balance-sheet fiscal agency (OBFA) that has been hailed as Europe’s Hamiltonian moment and raised great expectations for future fiscal integration. Building on the emerging Critical Macro-Finance literature, we scrutinise both the RRF and the debt instruments it issues. We find that its innovative legal construction yielded ‘Schrödinger’s OBFA’: The RRF has an ‘institutional ambiguity’ which places it simultaneously on and off the EU budget to mitigate the EU fiscal rules. Moreover, as it lacks ‘immortality’ due to its exceptional and temporary nature, it is alive and already dead from a financial market perspective. As Schrödinger’s OBFA, the RRF’s institutional status places inherent limitations on the EU’s ongoing process of incremental fiscal integration and makes it incapable of issuing securities that could assume the status of European safe assets
A Systems Perspective: How Social–Ecological Networks Can Improve Our Understanding and Management of Biological Invasions
No full textReversing biodiversity loss and the sustainability crisis requires approaches that explicitly consider human–nature interdependencies. Social–ecological networks, which incorporate social and ecological actors and entities, as well as their interactions, provide such an approach. Social–ecological networks have been applied to a range of complex issues, including sustainable resource use, management of ecosystem services and disservices, and collective action. However, the application of social–ecological networks to invasion science remains limited so far, despite their clear potential for studying human contributions to introduction pathways of nonnative species, invasion success, direct and indirect impacts, and their management. In the present article, we review past applications of social–ecological networks to biological invasions, provide guidance on how to construct and analyze such networks, with an illustrative example, and outline future opportunities of social–ecological networks in invasion science. We aim to inform and inspire the applications of social–ecological networks to improve our ability to meet the diverse challenges facing invasion science