Unraveling the physics of the Yellowstone magmatic system using geodynamic simulations

The Yellowstone magmatic system is one of the largest magmatic systems on Earth, and thus an ideal location to study magmatic processes. Whereas previous seismic tomography results could only image a shallow magma reservoir, a recent study using more seismometers showed that a second and massive partially molten mush reservoir exists above the Moho (Huang et al., 2015). To understand the measurable surface response of this system to visco-elasto-plastic deformation, it is thus important to take the whole system from the mantle plume up to the shallow magma reservoirs into account. Here, we employ lithospheric-scale 3D visco-elasto-plastic geodynamic models to test the influence of parameters such as the connectivity of the reservoirs and rheology of the lithosphere on the dynamics of the system. A gravity inversion is used to constrain the effective density of the magma reservoirs, and an adjoint modeling approach reveals the key model parameters affecting the surface velocity. Model results show that a combination of connected reservoirs with plastic rheology can explain the recorded slow vertical surface uplift rates of around 1.2 cm/year, as representing a long term background signal. A geodynamic inversion to fit the model to observed GPS surface velocities reveals that the magnitude of surface uplift varies strongly with the viscosity difference between the reservoirs and the crust. Even though stress directions have not been used as inversion parameters, modeled stress orientations are consistent with observations. However, phases of larger uplift velocities can also result from magma reservoir inflation which is a short term effect. We consider two approaches: (1) overpressure in the magma reservoir in the asthenosphere and (2) inflation of the uppermost reservoir prescribed by an internal kinematic boundary condition. We demonstrate that the asthenosphere inflation has a smaller effect on the surface velocities in comparison with the uppermost reservoir inflation. We show that the pure buoyant uplift of magma bodies in combination with magma reservoir inflation can explain (varying) observed uplift rates at the example of the Yellowstone volcanic system

Structural and evolutionary classification of Type II restriction enzymes based on theoretical and experimental analyses

For a very long time, Type II restriction enzymes (REases) have been a paradigm of ORFans: proteins with no detectable similarity to each other and to any other protein in the database, despite common cellular and biochemical function. Crystallographic analyses published until January 2008 provided high-resolution structures for only 28 of 1637 Type II REase sequences available in the Restriction Enzyme database (REBASE). Among these structures, all but two possess catalytic domains with the common PD-(D/E)XK nuclease fold. Two structures are unrelated to the others: R.BfiI exhibits the phospholipase D (PLD) fold, while R.PabI has a new fold termed ‘half-pipe’. Thus far, bioinformatic studies supported by site-directed mutagenesis have extended the number of tentatively assigned REase folds to five (now including also GIY-YIG and HNH folds identified earlier in homing endonucleases) and provided structural predictions for dozens of REase sequences without experimentally solved structures. Here, we present a comprehensive study of all Type II REase sequences available in REBASE together with their homologs detectable in the nonredundant and environmental samples databases at the NCBI. We present the summary and critical evaluation of structural assignments and predictions reported earlier, new classification of all REase sequences into families, domain architecture analysis and new predictions of three-dimensional folds. Among 289 experimentally characterized (not putative) Type II REases, whose apparently full-length sequences are available in REBASE, we assign 199 (69%) to contain the PD-(D/E)XK domain. The HNH domain is the second most common, with 24 (8%) members. When putative REases are taken into account, the fraction of PD-(D/E)XK and HNH folds changes to 48% and 30%, respectively. Fifty-six characterized (and 521 predicted) REases remain unassigned to any of the five REase folds identified so far, and may exhibit new architectures. These enzymes are proposed as the most interesting targets for structure determination by high-resolution experimental methods. Our analysis provides the first comprehensive map of sequence-structure relationships among Type II REases and will help to focus the efforts of structural and functional genomics of this large and biotechnologically important class of enzymes

Effect of remote ischaemic conditioning on clinical outcomes in patients with acute myocardial infarction (CONDI-2/ERIC-PPCI): a single-blind randomised controlled trial.

BACKGROUND: Remote ischaemic conditioning with transient ischaemia and reperfusion applied to the arm has been shown to reduce myocardial infarct size in patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI). We investigated whether remote ischaemic conditioning could reduce the incidence of cardiac death and hospitalisation for heart failure at 12 months. METHODS: We did an international investigator-initiated, prospective, single-blind, randomised controlled trial (CONDI-2/ERIC-PPCI) at 33 centres across the UK, Denmark, Spain, and Serbia. Patients (age >18 years) with suspected STEMI and who were eligible for PPCI were randomly allocated (1:1, stratified by centre with a permuted block method) to receive standard treatment (including a sham simulated remote ischaemic conditioning intervention at UK sites only) or remote ischaemic conditioning treatment (intermittent ischaemia and reperfusion applied to the arm through four cycles of 5-min inflation and 5-min deflation of an automated cuff device) before PPCI. Investigators responsible for data collection and outcome assessment were masked to treatment allocation. The primary combined endpoint was cardiac death or hospitalisation for heart failure at 12 months in the intention-to-treat population. This trial is registered with ClinicalTrials.gov (NCT02342522) and is completed. FINDINGS: Between Nov 6, 2013, and March 31, 2018, 5401 patients were randomly allocated to either the control group (n=2701) or the remote ischaemic conditioning group (n=2700). After exclusion of patients upon hospital arrival or loss to follow-up, 2569 patients in the control group and 2546 in the intervention group were included in the intention-to-treat analysis. At 12 months post-PPCI, the Kaplan-Meier-estimated frequencies of cardiac death or hospitalisation for heart failure (the primary endpoint) were 220 (8·6%) patients in the control group and 239 (9·4%) in the remote ischaemic conditioning group (hazard ratio 1·10 [95% CI 0·91-1·32], p=0·32 for intervention versus control). No important unexpected adverse events or side effects of remote ischaemic conditioning were observed. INTERPRETATION: Remote ischaemic conditioning does not improve clinical outcomes (cardiac death or hospitalisation for heart failure) at 12 months in patients with STEMI undergoing PPCI. FUNDING: British Heart Foundation, University College London Hospitals/University College London Biomedical Research Centre, Danish Innovation Foundation, Novo Nordisk Foundation, TrygFonden

Friction Force Microscopy as a tool to investigate (electro)catalytic processes at surfaces

Friction Force Microscopy as a tool to investigate (electro)catalyticprocesses at surfacesM.Maksumov1,2, A. Kaus2,3, Z. Teng4, K. Kleiner4, F. Gunkel3, F. Hausen1,21Forschungszentrum Jülich, IEK-9, 52428 Jülich, Germany2RWTH Aachen University, IPC, Landoltweg 2, 52065 Aachen, Germany3Forschungszentrum Jülich, PGI-7, 52428 Jülich, Germany4University of Münster, MEET, Correnstraße 46, 48149 Münster, [email protected]@fz-juelich.deA thorough understanding of (electro)catalytic surface transformations under dynamic reaction conditions is of utmost importance for a knowledge-based catalyst design. Friction Force Microscopy (FFM) as an atomic force microscopy based technique is capable to obtain materials specific information in addition to electrical and structural properties of catalysts in liquid media and under electrochemical conditions. This is especially relevant as surface transitions at early catalytic activity are subtle and might be easily overseen by pure topography mapping.It is the objective of this work to demonstrate the capabilities of FFM for investigating (electro)catalysts. It has been shown earlier that the frictional behavior of a bare metal differs significantly from its oxy/hydroxy-terminated surface under electrochemical conditions.The new results on combined electrochemical and frictional experiments on well-defined epitaxial perovskite oxide structures in aqueous liquids are illustrated. This approach represents the first application of these technique with respect to (electro)catalysis. Simultaneously recorded cyclic voltammograms and lateral forces, so-called frictograms, allow to correlate subtle and local surface transformations and the applied potential precisely.In conclusion, FFM represents a versatile new operando technique to investigate (electro)catalytic reactions under dynamic conditions on a local scale with high sensitivity to materials and structural changes

Friction Force Microscopy as a tool to investigate (electro)catalytic activities at surfaces

Production of green hydrogen energy based on water electrolysis, currently, have become one of the crucial topics in the framework of energy transition towards green energy technologies. In water splitting electrolysis catalysis or electrocatalysts play a critical role, where the development of active, stable and low-cost electrocatalysts is always on the agenda of the research works. [1] Designing of electrocatalysts with fundamental understanding of their surface transformations under dynamic reaction conditions still remains very challenging. This requires a fundamental understanding of all the processes involved on the atomic level, which is the main focus of my research work and part of the common goals of DFG Priority Programme 2080. The slow reaction kinetics at oxygen evolution reaction (OER) due to high overpotentials keep electrolysis from being of practical use and perovskites, as catalysts, could be used to minimize the overpotentials. However, perovskite electrocatalysts suffer from irreversible degradation reactions such as undesired surface transformations and morphology changes at grain boundaries and surfaces. [2-3] A comprehensive understanding of perovskite surface transformations under dynamic OER conditions at atomic level could be achieved by implementation of different electrochemical scanning probe microscopy techniques. Mainly, to investigate fundamental processes at the solid/liquid interface in electrocatalysis advanced atomic force microscopy (AFM) and scanning tunneling microscopy (STM) are employed in liquid environment under applied voltage bias. AFM enables the collection of data regarding the nanomechanical, electrical, and structural properties of sample in addition to the standard topography map that is captured. This is highly valuable considering sole topography mapping likely to miss the expected surface changes at the beginning of the OER. Previously, F. Hausen et al [4] applying a common tribology method based on AFM, operando electrochemical friction force microscopy (EC-AFM), reported that friction differences between a bare metal and and oxy/hydroxy-terminated surface in liquid environment clearly indicates direct fingerprint of chemical surface transformation. In our work, we investigate exclusively epitaxially grown perovskite oxide catalysts based on La1-xSrxCoO3 in alkali environment before and after electrocatalysis under dynamic and steady state operation conditions (as illustrated in Fig.1). Figure 1 clearly illustrates the difference of surface between as-grown perovskite oxide with the higher average friction of 18-20 nN than the post-catalaysis perovskite oxide with the average friction of 10-12 nN. The relevance of this research work and necessity to exchange the ideas with researchers around the world working on hydrogen energy technologies is highly encouraged from SPP2080 project as well as well aligned within the scope of H2Educate program from National Energy Education Development (NEED Project, US), which was designed to promote young researchers with educational materials, training and exchange programs. Figure 1. Friction maps of as-grown and post-catalysis of LaxSr1-xCoO3 in air, a and b respectively.1. Wang S., Lu A., Zhong CJ. Hydrogen production from water electrolysis: role of catalysts. Nano Convergence 8, 4 (2021). 2. Grimaud, A. et al. Double perovskites as a family of highly active catalysts for oxygen evolution in alkaline solution. Nat. Commun. 4, 2439 (2013).3. Wan, G. et al. Amorphization mechanism of SrIO3 electrocatalyst: How oxygen redox initiates ionic diffusion and structural reorganization. 4. Hausen, F. et al. Anion adsorption and atomic friction on Au (111). Electrochimica Acta. 56, 28, 10694-10700 (2011)