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Numerous research results have already pointed towards the negative influence of increased mental stress on educational processes and motivational criteria. It has also been shown that the global public health crisis induced by COVID-19 was related to anxiety symptoms and elevated levels of distress. To holistically elucidate the dynamics of the pandemic-related mental stress of first-year medical students, the associated parameters of three different cohorts were measured at the beginning of the pandemic-related restrictions on university life in Germany (20/21), at the peak of the COVID-19-related restrictions (21/22) and during the easing of the restrictions in the winter term 22/23. In a repeated cross-sectional study design, the constructs of worries, tension, demands and joy were collected from first-year medical students (n = 578) using the Perceived Stress Questionnaire. The results demonstrate significantly increased values of the constructs worries (p < 0.001), tension (p < 0.001) and demands (p < 0.001) at the peak of the pandemic related restrictions compared to the previous and following year as well as significantly decreasing values of general joy of life during the observed period of 3 years (all p-values < 0.001). A confirmatory factor analysis was performed to verify the questionnaire’s factor structure regarding the addressed target group during the pandemic (CFI: 0.908, RMSEA: 0.071, SRMR: 0.052). These data, collected over a period of three years, provide information regarding dynamically manifesting mental stress during the COVID-19 pandemic, and refer to new areas of responsibility for the faculties to adequately counteract future crisis situations.

The variability of the molecular composition of dissolved organic matter (DOM) in soils is predominantly explained by microbial mineralization and assimilation as well as interactions with mineral surfaces and soil organic matter (SOM). From a temperate site with calcareous soil it is established that the molecular composition of DOM shifts from plant-derived towards microorganism-derived signals in soil depth profiles. This variability is largely explained by microbial activity and only to a minor degree by soil-derived parameters like texture and SOM. Here we analyze the molecular composition of DOM in depth profiles of tropical rainforest soils in order to compare its variability to the temperate site as the tropical ecosystems have larger variability in soil texture and mineralogy and lower SOM content. We collected porewater in soil profiles of four ecosystems belonging to two major Amazon rainforest types, terra firme forest on clay soils and white-sand forest on sandy soils. We analyzed the molecular composition of DOM using solid-phase extraction and ultrahigh resolution mass spectrometry.The concentration and composition of DOM differed strongly between the sandy white-sand and clayey terra firme sites. DOM concentration in white-sand soils was much higher and decreased less with depth compared to the terra firme forests. Topsoil DOM in white-sand forests was characterized by high abundance of aromatic plant-derived compounds, whereas it reflected a stronger microbial imprint in terra firme sites. The molecular composition of DOM changed significantly with depth at all sites. In both terra firme and one white-sand forest the transformation was consistent with the expected shift from plant-derived signals towards increasing microbial reworking. The Bray-Curtis dissimilarity between topsoil and greater depth was considerably higher in terra firme compared to white-sand soils with values of 0.32 +- 0.06 and 0.14 +- 0.04, respectively, suggesting much slower DOM transformation in sandy soils. The dissimilarity was correlated similarly to pH, clay content and mineralogy (Pearson R2 = 0.27, 0.21 and 0.23, respectively). The high dissimilarity in the terra firme sites that vary strongly in clay content and mineralogy was only significantly correlated to pH (R2 = 0.16). This suggests that clay content and mineralogy, likely linked to DOM adsorption, were less important for the observed depth trend, which aligns with results from the temperate site. The significant effect of soil pH on the molecular transformation is in line with the importance of microorganisms for DOM transformation as soil pH is a major control on microbial community structure. Overall, our results suggest that similar processes control DOM transformation in temperate and tropical ecosystems, which are likely linked to microbial processing and formation of DOM.

The lake Laacher See (East Eifel, Germany) is affected by eutrophication due to high phosphorous concentration for stagnant waters averaging 34 µg/l (range of 25–40 µg/l P since the year 2000). These elevated concentrations have been monitored since the 1950s and an oligotrophic status could not be achieved despite various measures [2]. A linear correlation was determined between dissolved phosphate (211 – 643 μg/l) and vanadium (6.7 – 28.4 μg/l) in groundwaters of the Ringseitert volcanic complex (West Eifel) with implications for drinking water use [4]. These issues are the motivation to investigate the geogenic input of phosphorous into Laacher See and of vanadium into groundwaters by fluid-rock-interaction.Laacher See is the water-filled crater area of the Plinian-erupted Laacher-See-volcano, which belongs to the East Eifel Volcanic Field with an active volcanism for 0.46 Ma [6]. The catchment of this lake includes rocks of siliciclastic Lower Devonian basement, scoria cones and lava flows of basanitic and tephritic compositions, and phonolithic to foiditic tephra from the Rieden volcanic complex. The youngest volcanic unit is the phonolithic, strong geochemically zoned tephra from the Laacher-See-volcano, which ejected 6 km³ magma in form of pumice and ash 12.9 ka ago [3,6].The dissolution of apatite (primary) and vivianite (secondary phosphate phase) is assumed to be the reason of geogenic input of phosphorous and vanadium by groundwater flow. A particularity of the Laacher See area is the occurrence of mofettes that lead to elevated concentrations of CO2, decreased pH and enhanced apatite dissolution [5]. The hydrochemical modelling program PHREEQC is used to investigate the equilibrium state of phosphate and vanadium in groundwaters at specific Eh/pH-conditions, p(CO2)-values and compositions. In addition, residence times calculated by hydraulic conductivities and dissolution rates from batch experiments are used to distinguish between rate-limited or equilibrium process in phosphate dissolution. Data on phosphorous concentrations and pH of soils in the vicinity of the Laacher See and their equilibrium solutions are evaluated to their geological, geochemical and anthropogenic background and provide clues to phosphorous sources [1].In future studies, bulk rock concentrations will be measured using XRF and total digestion, and detailed dissolution rates will be measured using extended batch experiments to combine these findings into a conceptual hydrogeological model of geogenic phosphate and vanadium input to lake Laacher See.References:[1] Armbruster, M. & Wiesler, F. 2012. Ermittlung der P-Gehalte entlang von 10 Transekten am Laacher See. LUFA Speyer, Speyer. P.24 (unpublished)[2] Block, U. et al. 2015. Übersicht über die Phosphatthematik am Laacher See. Fachhochschule Bingen. P.41[3] Bogaard, P.v.d. & Schmincke, H.U. 1984. The eruptive center of the late quaternary Laacher see tephra. Geologische Rundschau, 73, 933-980, http://doi.org/10.1007/BF01820883.[4] Härter, L.M. et al. 2020. Vorkommen von Vanadium im Grundwasser der Vulkaneifel. Grundwasser, 25, 127-136, http://doi.org/10.1007/s00767-020-00447-x.[5] Pan, H.B. & Darvell, B.W. 2009. Calcium Phosphate Solubility: The Need for Re-Evaluation. Crystal Growth & Design, 9, 639-645, http://doi.org/10.1021/cg801118v.[6] Schmincke, H.-U. 2007. The Quaternary Volcanic Fields of the East and West Eifel (Germany). In: Ritter, J.R.R. & Christensen, U.R. (eds) Mantle Plumes: A Multidisciplinary Approach. Springer Berlin Heidelberg, Berlin, Heidelberg, 241-322, http://doi.org/10.1007/978-3-540-68046-8_8

International audience; In the current study, contrasting growth behaviour of redox sensitive Fe0 nanoparticles (nZVI)was observed on different clay surfaces i.e., 1:1 non-swelling kaolinite (K-nZVI) and 2:1swelling bentonite (B-nZVI). Osmotic swelling of bentonite led to Fe0 nucleation and growthof 5-7 nm size particles in the broadened interlayer spaces. B-nZVI had negative zeta potentialdue to the domination of the surface charge of bentonite clay. Whereas kaolinite has showndominant surface growth of nZVI particles (>24.8±7.4 nm) and positive zeta potential,suggesting domination of Fe0 nanoparticles (nZVI) characteristics. This surface-dependentvariation led to higher and faster removal of oxy-anions with K-nZVI, i.e., chromium andarsenic (87.5 and 157.35 mg/g) than B-nZVI (18.4 and 86.9 mg/g). In comparison, B-nZVI hasshown higher sorption of cations i.e., nickel and cadmium (36 mg/g and 46 mg/g) than K-nZVI(25 and 27 mg/g). XPS and pXRD analysis of reaction precipitates confirmed reductivesorption of chromium, co-precipitation/ complexation of arsenic, electrostatic attraction andcomplexation of nickel and cadmium as major removal mechanisms. Drastically higher totalcontaminant sorption capacities of B-nZVI (327 mg/g) and K-nZVI (372 mg/g) in multicontaminant(Cr+As+Ni+Cd) solutions than individual capacities in mono-ionic solutions wasdue to co-operative effects and newer sites induced via sorption and redox-transformation ofother ionic species. K-nZVI removed chromium and arsenic to below drinking waterpermissible limits whereas B-nZVI succeeded in separating nickel and cadmium to drinkablelevels in groundwater, freshwater, river water, and wastewater samples, emphasizing theirapplicability in high cationic—low anionic and low cationic-higher anionic speciescontaminated waters, respectively.

Anthropogenic phosphorus (P) input from fertilised and unfertilised topsoils into surface water and re-dissolution from sediments can be key drivers of eutrophication. This study aimed to (1) analyse the P input processes into streams/rivers particularly via erosion from fertilised and unfertilised fields and (2) study the effectiveness of the riparian strip in reducing P emissions from diffuse sources. For the investigation, Cambisol-Tschernosem and Luvisol samples from Loess were taken from Thuringian test fields (Germany). Three laboratory simulations were designed to analyse P re-dissolution and leaching behaviour from topsoils and sediments and further extrapolated to a realistic scenario based on the P input path into receiving waters via erosion. Organic bonded phosphorus and orthophosphate were leached out at the beginning. Upscaling to a realistic scenario showed that the main source of P in receiving waters was leaching from sediment interstitial sites (57.5%) via percolation while the P re-dissolution via diffusion (13%), due to two heavy rain events (17%), and leaching from soil interstitial sites (12.5%) only played a minor role. The risk of eutrophication exceeded the threshold total P of 0.10 mg L-1 given as an orientation value by the Federal/State water consortium (LAWA). This was observed in percolates from all sandy soils (0.17–0.85 mg L-1), only slightly in the clayey soils (≤ 0.11 mg L-1) but not in either streambed sediment (≤ 0.08 mg L-1). However, local differences such as steeper slope, different soil compositions such as higher sand and lower clay percentages, and poorer buffering due to lower lime and aluminium content were identified as reasons for a higher risk of eutrophication.

Objectives: Accurate self-assessment and -reflection of competencies are crucial skills for all health professions. The National Competence-Based Learning Objectives Catalogue (NKLM) guiding medical faculties in Germany points out reflection as a non-technical skill and competency-based medical education (CBME) as important approaches. In this context, the role and structure of curricula and skills labs evolved. Especially in peer-assisted trainings, reflection of competencies is important to improve self-regulated learning. Traditionally, we assume self-reflection skills to evolve automatically with learners’ experience. This approach aims to find empirical evidence for this assumption and implements self-reflection of competencies in clinical skills education. Here, we quantify the influence of age and semester of study and its interaction on the concordant self-reflection of students’ own competencies. Methods: Investigation was based on a retrospective analysis of evaluation data from peer-assisted “first aid” and “physical examination” courses in the skills labs of the medical faculty at the Ruhr-University Bochum, Germany. Participants were asked for self-assessed competencies before (pre) and after (post) the course. Additionally, they were asked to retrospectively re-rate their “before” competencies after completing the course (post-pre). Differences between pre and post-pre competencies were assessed as the concordant self-reflection in a moderated regression analysis. Group means and standard deviation were depicted using univariate analysis of variance (ANOVA) with post-hoc Tukey HSD testing in IBM SPSS Statistics V.28. Moderated regression and simple slope analyses were conducted to calculate interaction effects of age and semester of study on the concordant self-reflection. Results: As expected, participants (n = 168) showed significant progress in subjective self-assessment (pre vs. post) in all 18 assessed domains in the course (all p < 0.001). Additionally, participants self-assessed their previous competencies after the course (post-pre) differently than before the course (pre) in 11 out of 18 domains. Hereby, the interaction of age and semester of study explained a significant part of variance in the first aid course (∆R2 = 0.008, ∆F (1;1020) = 8.53, p < 0.005) and in the physical examination course (ΔR2 = 0.03, ΔF (1;10,280) = 10.72, p < 0.001). Conclusions: We quantified that interaction of age and semester has a significant influence on concordant self-reflection skills using a moderated regression analysis. Assumed as an indicator, we conclude that advanced and older students show less differences in pre- vs. post-pre-ratings. This has implications for curriculum development, postulating that an exposure to self-reflection as a metacognitive process should be introduced early in order to train competencies in health professionals. Prospective studies with competency-based assessments are necessary to validate findings.

Chromite ore processing residues (COPR) are real environmental threats, leading to CrO42-, i.e., Cr (VI) leaching into groundwater. It is of serious concern as Cr (VI) is proven to be carcinogenic. Here we emphasize the application of novel and eco-friendly chitin functionalized iron-enriched hydroxyapatite nanocomposite (HAP-Fe0-Ct) in the remediation of Cr (VI)-contaminated groundwater samples collected from Khan Chandpur, India, where the level of Cr (VI) is found to be 11.7 mg/L in a complex aqueous matrix having 793 mg/L of total dissolved solids. Chitin functionality in the composite has resulted in positive zeta potential at circum-neutral pH, favoring electrostatic attraction of chromate ions and resulting in its bulk surface transport. The HAP-Fe0-Ct showed faster kinetics of removal with efficiency (qm = 13.9 ± 0.46 mg/g) for Cr (VI). The composite has shown sorption equilibrium and 100% removal of Cr (VI) within 3 h of interaction time in groundwater samples. No Cr (VI) leaching in the acid wash process at pH 3.5 also suggests chromium’s strong chemisorption onto nanocomposite. During the interaction in aqueous solutions, the reduced iron (Fe0) on the nanocomposite becomes oxidized, suggesting the probable simultaneous reduction of Cr (VI) and its co-precipitation. Continuous column extraction of chromate ions was also efficient in both spiked solutions (39.7 ± 0.04 mg/g) and COPR contaminated water (13.2 ± 0.09 mg/g). Reusability up to three cycles with almost complete Cr (VI) removal may be attributed to surface protonation, new binding sites generation, and electron transfer from Fe0 core through defects. The study concludes that HAP-Fe0-Ct could be utilized for continuous Cr (VI) removal from COPR contaminated complex groundwater matrices.

It is our great pleasure to briefly introduce our motivation to collect scientific contributions for this Special Issue, entitled “Nano Geochemistry” [...]

Fungi living in heavy metals and radionuclides contaminated environments, namely the Chernobyl Exclusion Zone need to be able to cope with these pollutants. In this study, the wood-rot fungus Schizophyllum commune was investigated for its metal tolerance mechanisms, and for its ability to transport such metals through its hyphae. Effects of temperature and pH on tolerance of Cs, Sr, Cd, and Zn were tested. At concentrations allowing for half-maximal growth, adapted strains were raised. The strontium-adapted strain, S. commune 12-43 Sr, showed transport of specifically Sr over distances on a cm-scale using split plates. The adaptation did not yield changes in cell or colony morphology. Intracellular metal localization was not changed, and gene expression profiles under metal stress growing on soil versus artificial medium showed a higher impact of a structured surface for growth on soil than with different metal concentrations. In the transcriptome, transporter genes were mostly down-regulated, while up-regulation was seen for genes involved in the secretory pathway under metal stress. A comparison of wildtype and adapted strains could confirm lower cellular stress levels leading to lack of glutathione S-transferase up-regulation in the adapted strain. Thus, we could show metal transport as well as specific mechanisms in metal stress avoidance.

The Long-term In-situ Test (LIT) of the Colloid Formation and Migration project (CFM) at the Grimsel Test Site, investigates the generation of bentonite colloids and, hence, radionuclide mobilization within a well-defined and controlled shear zone in a crystalline rock. In this context, the determination of radionuclide aqueous speciation is essential to understand whether radionuclides are easily transported or immobilized by precipitation or uptake processes in the bentonite barrier included in a repository concept for nuclear waste, and mimic in the LIT experiment. The objective of this work is to determine the aqueous speciation of seven radionuclides (i.e. 75Se(VI), 99Tc(VII),233U(VI), 237Np(V), 241Am(III), Th(IV) and 242Pu(IV)) by thermodynamic calculations in different water compositions representing the geochemical evolution through the LIT. A comparison of the results obtained from two different modelling groups allows the identification of the geochemical key parameters affecting radionuclide mobility in this context and the corresponding numerical and conceptual uncertainties. Particularly, silicate complexes of trivalent actinides and uranium(VI) carbonato complexes (i.e. CanUO2(CO3)3(4-2n) n = 1 or 2) seem to be crucial in these environments, even at reducing conditions. Conceptual uncertainties like inclusion/exclusion of tetravalent actinide-bearing colloids formation and polyselenides have clearly been identified.

In the frame of studies on the safe disposal of nuclear waste, there is a great interest for understanding the migration behavior of 99Tc. 99Tc originating from nuclear energy production and global fallout shows environmental levels down to 107 atoms/g of soil (∼2 fg/g). Extremely low concentrations are also expected in groundwater after diffusion of 99Tc through the bentonite constituting the technical barrier for nuclear waste disposal. The main limitation to the sensitivity of the mass spectrometric analysis of 99Tc is the background of its stable isobar 99Ru. For ultratrace analysis, the Accelerator Mass Spectrometry (AMS) setup of the Technical University of Munich using a Gas-Filled Analyzing Magnet System (GAMS) and a 14 MV Tandem accelerator is greatly effective in suppressing this interference. In the present study, the GAMS setup is used for the analysis of 99Tc in samples of the seawater reference material IAEA-443, a peat bog lake, and groundwater from an experiment of in situ diffusion throug...

To assess a reliable safety case for future deep underground repositories for highly active nuclear waste the retention of radionuclides by the surrounding host rock must be understood comprehensively. Retention is influenced by several parameters such as mineral heterogeneity and surface roughness, as well as pore water chemistry (e.g., pH). However, the interplay between those parameters is not yet well understood. Therefore, we present a correlative spectromicroscopic approach to investigate sorption of the actinide Cm(III) on: 1) bulk K-feldspar crystals to determine the effect of surface roughness and pH (5.5 and 6.9) and 2) a large feldspar grain as part of a complex crystalline rock system to observe how sorption is influenced by the surrounding heterogeneous mineralogy. Our findings show that rougher K-feldspar surfaces exhibit increased Cm(III) uptake and stronger complexation. Similarly, increasing pH leads to higher surface loading and stronger Cm(III) binding to the surface. Within a heterogeneous mineralogical system sorption is further affected by neighboring mineral dissolution and competitive sorption between mineral phases such as mica and feldspar. The obtained results express a need for investigating relevant processes on multiple scales of dimension and complexity to better understand trivalent radionuclide retention by a potential repository host rock.

International audience; For the prevention of freshwater reservoirs from contamination through industrial effluents, eco-friendly adsorbents with minimal aging impact are required. Here, redox-sensitive nanoscale zero-valent iron(nZVI) particles were supported on four different surfaces with varying bentonite(B)/charcoal(C) ratio to mimic layered and porous surfaces. Different dyes, i.e. rhodamine-B(RB) and methylene blue(MB) were reacted with redox-sensitive supported nZVI composites, and degradation mechanisms were delineated using FT-IR spectroscopic analysis of reaction precipitates. A 300-day exposure to open-air was provided to the composites to comparatively evaluate the impact of aging on their reactivity for dyes in wastewater.Results interpret that dyes removal was a combination of different interfacial chemical processes, i.e., reduction or organic degradation probably through Fenton like processes, along with sorption. These mechanisms were found to be surface dependent, i.e., nZVI on charcoal enriched porous surfaces, degrade dyes through organic degradation while on layered clay surfaces, MB gets removed through reduction with limited and slower RB removal. Nanocomposites show a minimal impact of aging with removal capacities >100 mg/g for BC-1/3-nZVI and C-nZVI for MB and 50-75 mg/g for RB with significant removal in wastewater. Overall, the study concludes C-nZVI and novel BC-1/3-nZVI as two efficient dye adsorbents with minimal aging impact.

Atmospheric particulate matter has become a major issue in urban areas from both a health and an environmental perspective. In this context, biomonitoring methods are a potential complement to classical monitoring methods like impactor samplers, being spatially limited due to higher costs. Monitoring using spider webs is compared with the more common moss bag technique in this study, focusing on mass fractions and ratios of elements and the applicability for source identification. Spider webs and moss bags with Hypnum cupressiforme were sampled at the same 15 locations with different types of traffic in the city of Jena, Germany. In the samples, mass fractions of 35 elements, mainly trace metals, were determined using inductively coupled plasma-optical emission spectroscopy (ICP-OES) and inductively coupled plasma-mass spectrometry (ICP-MS) after aqua regia digestion. Significantly higher mass fractions in spider webs than in moss bags were found, even after a much shorter exposure period, and could not be ascribed completely to a diluting effect by the biological material in the samples. Different mechanisms of particle retention by the two materials are therefore assumed. More significant correlations between elements have been found for the spider web dataset. Those patterns allow for an identification of different sources of particulate matter (e.g. geogenic dust, brake wear), while correlations between elements in the moss bags show a rather general anthropogenic influence. Therefore, it is recommended to use spider webs for the short-term detection of local sources while moss bag biomonitoring is a good tool to show a broader, long-term anthropogenic influence.

Background: The prevalence of obstructive sleep apnea (OSA) is very high in stroke patients, whereas the acceptance of positive airway pressure (PAP) therapy is low. Although telemedicine offers new options to increase acceptance, effective concepts and patient groups are not yet known. Objective: The aim of this study was to investigate the effect of a telemedicine concept consisting of telemonitoring and support when usage time drops. Methods: PAP naive stroke patients with apnea-hypopnea index (AHI) >15 were randomized in a prospective parallel design comparing home therapy with standard care (SC) as opposed to telemedicine care (TC) over a period of 6 months. The TC group received a standardized phone call to offer help and advice if the average weekly usage of PAP fell below 4 h/night. Results: Eighty patients were included, 5 were lost to follow-up, 75 (20 females, age: 57.0 ± 9.9, body mass index: 30.9 ± 6.0 kg/m2, AHI: 39.4 ± 18.6) were evaluated. While inpatient usage was similar in both groups, a significant difference was identified after 6 months of receiving home therapy (TC: 4.4 ± 2.5 h, SC: 2.1 ± 2.2 h; p < 0.000063). On average, 4.7 ± 3.1 interventional phone calls were needed (173 calls in total, ranging from 0 to 10 calls per patient), primarily for the purpose of motivation (61.3%), mask problems (16.2%), nasopharyngeal complaints or humidification issues (11.2%), and technical questions (10.6%). Sleepiness (Epworth Sleepiness Scale [ESS]) differed significantly (TC: 3.7 + 3.2, SC: 6.1 + 4.1; p = 0.008), as well as systolic blood pressure, which was available in a subgroup of 55 patients (TC: 129.5 + 15.2 mm Hg, SC: 138.8 + 16.1 mm Hg; p = 0.034). Conclusion: A concept of telemonitoring and short telephone calls from the sleep lab raised PAP therapy adherence significantly in a group of stroke patients with moderate to severe OSA.

Experimental and theoretical studies were conducted to identify the molecular-scale reaction mechanism for Cr(VI) removal by a ferrous phosphate mineral, vivianite. The surface-normalized rate constant for Cr(VI) removal in a vivianite suspension at pH 7 was higher than those obtained for other Fe(II)-containing minerals (i.e., magnetite and pyrite). The highest rate constant was obtained at pH 5, which was 35- and 264-times higher than those obtained at pH 7 and 9, respectively, indicating the dramatic acceleration of removal kinetics with decreasing pH of suspension. The X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge structure (XANES) spectroscopy revealed that Cr(VI) removal involved reduction of Cr(VI) to Cr(III) coupled with oxidation of Fe(II) to Fe(III) on the vivianite surface. In addition, the density functional theory (DFT)-optimized structure of the Cr(VI)-vivianite complex was consistent with that obtained from extended X-ray absorption fine structure (EXAFS) spectroscopy and revealed the transformation of vivianite to amorphous Fe(III) phosphate. We also demonstrated that both Cr(VI) species, HCrO

The combination of in-flight separation with a gas-filled stopping cell has opened a new field for experiments with exotic nuclei. For instance, at the SHIP/SHIPTRAP facility at GSI in Darmstadt high-precision mass measurements of rare nuclei have been successfully performed. In order to extend the reach of SHIPTRAP to exotic nuclei that are produced together with high rates of unwanted reaction products, a novel compact radio frequency quadrupole (RFQ) system has been developed. It implements ion cooling, identification and separation according to mass numbers and bunching capabilities. The system has a total length of one meter only and consists of an RFQ cooler, an RFQ mass filter and an RFQ buncher. A mass resolving power (FWHM) of 240 at a transmission efficiency of 90% has been achieved. The suppression of contaminants from neighboring masses by more than four orders of magnitude has been demonstrated at rates exceeding 1 0 6 ions/s. A longitudinal emittance of 0.45 eV μ s has been achieved with the RFQ buncher, which will enable improved time-of-flight mass spectrometry downstream of the device. With this triple RFQ system the measurement of e.g. N = Z nuclides in the region up to tin will become possible at SHIPTRAP. The technology is also well suited for other rare-isotope facilities with experimental setups behind a stopping cell, such as the fragment separator FRS with the FRS Ion Catcher at GSI.

Scale formation processes in the surface installations of geothermal power plants may have a negative effect on power plant performance. In addition, scales formed within the geothermal water circuit frequently accumulate natural radionuclides. Consequently, scale formation may lead to radiation dose rates, which are of radiological concern, and deposits, which may have to be disposed as radioactive waste. In order to minimize these problems and to foster geothermal power plant availability, it is of major interest to understand scale formation processes and to develop methods for their inhibition. One important pre-requisite towards this goal is a sound mineralogical and geochemical characterization of the formed material. Geothermal brines at sites in the Upper Rhine Graben are in general highly mineralized and become, upon cooling in the heat exchanger, supersaturated with respect to sulfate solid-solutions, e.g. (Ba,Sr)SO 4 , and other mineral phases. Some geothermal power plants very successfully tested the application of sulfate scaling inhibitors. Here we present mineralogical analyses of scale samples from geothermal power plants in the Upper Rhine Valley deposited in absence and presence of sulfate scaling inhibitors. Solid samples are investigated using wet-chemistry (after digestion), XRPD, SEM-EDX, XPS, EA-IRMS, Raman spectroscopy, and XANES (for explanation of abbreviations, see main text). Samples of scales deposited in the absence of a sulfate scaling inhibitor mainly consist of two phases. The largest part is made up of a barite type (Ba,Sr,Ca)SO 4 solid-solution. Traces of Ra occurring in the scaling are assumed to be incorporated in the barite type solid solution. Further minor phases are sulfide phases, either an X-ray amorphous nano-particulate phase or galena (PbS). Since the application of the sulfate inhibitor, sulfate minerals are no longer detectable in the scale samples. Subsequent scalings are Pb-dominated and consist mainly of galena (PbS), elemental lead (Pb), arsenic (As) and antimony (Sb). As and Sb are likely present as a nanocrystalline intermetallic mixed compound ((Sb, As) or Pb 3 (Sb,As) 2 S 3 ). The absence of barite-type minerals demonstrates the success of the application of the sulfate inhibitor. The precipitation of elemental Pb, As, and Sb, which are more noble than iron, may enhance the corrosion of mild steel pipes in the geothermal water circuit. Elution tests and oxidation of the scalings upon storage at atmospheric conditions demonstrate that proper disposal of the toxic heavy metal and metalloid containing scalings may be challenging.

Elevated levels of particulate matter (PM) in urban atmospheres are one of the major environmental challenges of the Anthropocene. To effectively lower those levels, identification and quantification of sources of PM is required. Biomonitoring methods are helpful tools to tackle this problem but have not been fully established yet. An example is the sampling and subsequent analysis of spider webs to whose adhesive surface dust particles can attach. For a methodical inspection, webs of orb-weaving spiders were sampled repeatedly from 2016 to 2018 at 22 locations in the city of Jena, Germany. Contents of Ag, Al, As, B, Ba, Ca, Cd, Co, Cr, Cs, Cu, Fe, K, La, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, S, Sb, Si, Sn, Sr, Th, Ti, V, Y, Zn and Zr were determined in the samples using inductively coupled plasma-mass spectrometry (ICP-MS) and inductively coupled plasma-optical emission spectroscopy (ICP-OES) after aqua regia digestion. Multivariate statistical methods were applied for a detailed evaluation. A combination of cluster analysis and principal component analysis allows for the clear identification of three main sources in the study area: brake wear from car traffic, abrasion of tram/train tracks and particles of geogenic origin. Quantitative source contributions reveal that high amounts of most of the metals are derived from a combination of brake wear and geogenic particles, the latter of which are likely resuspended by moving vehicles. This emphasizes the importance of non-exhaust particles connected to road traffic. Once a source identification has been performed for an area of interest, classification models can be applied to assess air quality for further samples from within the whole study area, offering a tool for air quality assessment. The general validity of this approach is demonstrated using samples from other locations.

Surface chemistry of mineral phases in aqueous environments generates the electrostatic forces involved in particle-particle interactions. However, few models directly take into account the influence of surface speciation and changes in solution speciation when the diffuse layer potential profiles of approaching particles overlap and affect each other. These electrostatic interactions can be quantified, ideally, through charge regulation, considering solution and surface speciation changes upon particle approach by coupling state-of-the-art surface complexation models for the two particle surfaces with a Poisson-Boltzmann type distribution of electrostatic potential and ions in the inter-particle space. These models greatly improve the accuracy of inter-particle force calculations at small inter-particle separations compared to constant charge and constant potential approaches. This work aims at advancing charge regulation calculations by including full chemical speciation and advanced surface complexation models (Basic Stern-, three-, or four plane models and charge distribution concepts), for cases of similar and dissimilar surfaces involving the numerical solution of the Poisson-Boltzmann equation for arbitrary electrolytes. The concept was implemented as a Python-based code and in COMSOL. The flexibility and precision of both, concept and implementations are demonstrated in several benchmark calculations testing the new codes against published results or simulations using established speciation codes, including aqueous speciation, surface complexation and various interaction force examples. Due to the flexibility in terms of aqueous chemistry and surface complexation models for various geometries, a large variety of potential applications can be tackled with the developed codes including industrial, biological, and environmental systems, from colloidal suspensions to gas bubbles, emulsions, slurries like cement paste, as well as new possibilities to assess the chemistry in nano-confined systems.

This study investigates the appropriateness of monodisperse carboxylated polystyrene spheres as clay colloid analogues. Colloid transport experiments using Na-illite are conducted within a parallel-plate fracture flow cell with an aperture of 0.75 mm at pH 5 under low ionic strength (1 mM NaCl) and laminar flow (7 mL/h) conditions. The effects of collector surface material (Grimsel granodiorite or acrylic glass), fracture orientation and residence time on colloid retention are examined. In order to avoid full surface coverage effects, ultra-trace (30 ppb) Na-illite colloid concentrations are used. Laser-induced breakdown detection is applied in order to detect and quantify the Na-illite colloids. The results are directly compared to the experiments of Stoll, et al. [1] who investigated the transport and surface interaction of carboxylated polystyrene spheres (25 and 1000 nm diameter) using the same experimental setup and conditions. It is concluded that polystyrene spheres are no ideal analogue to predict the mobility and transport behavior of a polydisperse clay colloid suspension. Despite the higher solid density, the Na-illite colloids show higher mobility compared to the polystyrene spheres without significant impact of surface roughness or gravity. The platelet shape, the non-uniform surface charge distribution and slower sedimentation may account for the observed differences.

Die Schwangerschaft hat einen erheblichen Einfluss auf Atmungsregulation und Atemmechanik sowie auf die Schlafregulation: Durch seine Grosenzunahme schrankt der Uterus zwar die maximale willkurliche Ventilation ein, das Schwangerschaftshormon Progesteron hingegen bewirkt eine kompensierende Bronchodilatation und eine markante Hyperventilation mit arteriellen PCO2-Werten der Schwangeren unter 30 mmHg. Die Schlafqualitat nimmt in der Schwangerschaft ab, insbesondere aufgrund steigender Hormonspiegel des Progesterons, einer generellen Stoffwechselsteigerung, Nykturie, fetaler Bewegungen und wegen der Begunstigung schlafbezogener Atmungsstorungen. Beim Embryo entwickelt sich bereits in der 4. Woche die Lungenanlage und reift uber ein pseudoglandulares, kanalikulares, sakkulares zum alveolaren Stadium. Ab Schwangerschaftswoche 29 – 30 sezernieren Typ-2-Alveozyten Surfactant. Ab der Mitte des zweiten Trimenons sind fetale Atembewegungen nachweisbar. Ohne sie fehlt der Stimulus fur ein adaquates Lungenwachstum. Sie sind abhangig vom Ruhe-/Aktivitatsrhythmus des Fetusses und antworten auf erhohten Kohlendioxidpartialdruck, wahrend sie durch Sauerstoffmangel inhibiert werden. Die innere Uhr entwickelt sich beim Fetus im letzten Trimester und wird durch Zeitgeber der Mutter, zum Beispiel durch den Melatoninspiegel synchronisiert. In den letzten 10 Wochen der Schwangerschaft lassen sich Phasen ruhigen (NREM-) und aktiven (REM-)Schlafes differenzieren. Schwangerschaft und intrauterine Entwicklung sind von erheblichen Veranderungen von Atmung und Schlaf bei Mutter und Kind begleitet, die Ansatzpunkte pathophysiologischer Entwicklungen sein konnen. Schlafbezogene Atmungsstorungen (SBAS) in Form von Schnarchen oder obstruktivem Schlafapnoe-Syndrom (OSAS) sind auch bei Frauen insbesondere nach der Menopause haufige Schlafstorungen. Aber auch pramenopausal tritt das OSAS mit einer Haufigkeit von mehr als 2 % auf. Einige wahrend der Schwangerschaft auftretende physiologische Veranderungen sind prinzipiell in der Lage, das Auftreten von obstruktiven SBAS zu fordern. Gerade jungere Frauen haben aber oft eine nicht SBAS-typische Symptomatik. Screening-Fragebogen auf SBAS sind fur jungere Frauen und somit auch in der Schwangerschaft daher weniger geeignet. Die Pravalenzangaben von SBAS bei Schwangeren sind unterschiedlich je nach Definition, Methode und Untersuchungskollektiv. Schnarchen und OSA sind aber bei gesunden normalgewichtigen Frauen zu Beginn der Schwangerschaft eher selten. Ubergewicht und Alter sind die entscheidenden Risikofaktoren fur das Auftreten von pathologischem Schnarchen und OSAS zu Beginn der Schwangerschaft und fur die Zunahme der Haufigkeit wahrend der Schwangerschaft. Im 3. Trimenon muss mit einer Haufigkeit von SBAS von ca. 10 – 30 % gerechnet werden. Diese Schwangerschaften sind als Risikoschwangerschaften einzuschatzen und haben wahrscheinlich einen negativen Effekt auf maternal-fetale Morbiditat und Mortalitat. Die Koinzidenz von Schwangerschaft und OSAS stellt im Hinblick auf Schwangerschaftskomplikationen sowohl fur die Schwangere als auch das Ungeborene ein gesundheitliches Risiko dar. Frauen, die in der Schwangerschaft schnarchen, haben ein signifikant hoheres Risiko im Hinblick auf Erkrankungen wie Kardiomyopathie, Lungenembolie, Eklampsie und Praeklampsie sowie eine erhohte Muttersterblichkeit. Zu den sog. „adverse effects“ bei Ungeborenen bzw. Neonaten von Muttern mit OSAS zahlen die vorzeitige Geburt, haufigere Entbindung per Sectio caesarea, ein niedriges bzw. nicht altersentsprechendes Geburtsgewicht sowie ein signifikant niedrigerer 1- und 5-Minuten-APGAR-Wert. Aufgrund der potenziellen und verhaltnismasig haufigen Koinzidenz von Schwangerschaft und OSAS sowie der genannten Gefahrdung von Mutter und Kind mussen nicht nur Schlafmediziner, sondern auch insbesondere Gynakologen diesem Umstand zunehmend Beachtung schenken. Pregnancy has a significant influence on respiratory regulation and respiratory mechanics as well as on sleep regulation. Due to its increased size, the uterus restricts the maximum voluntary ventilation; the pregnancy hormone progresterone, on the other hand, causes compensatory bronchodilatation and marked hyperventilation with arterial PCO2 values of the pregnant women below 30 mmHg. Sleep quality decreases during pregnancy, especially due to increasing hormone levels of progesterone, general metabolism, nocturia, fetal movements, and the promotion of sleep-related breathing disorders. In the embryo, the lung develops as early as the 4th week and matures through a pseudoglandular, canalicular, sacular to the alveolar stage. From pregnancy week 29 – 30 type 2 alveocytes begin to produce surfactant. From the middle of the second trimester fetal respiratory movements are detectable. They cause the essential stimulus for adequate lung growth, are dependent on the resting/activity rhythm of the fetus and respond to increased carbon dioxide partial pressure, while they are inhibited by hypoxia. The fetal internal clock develops in the last trimester, and is controlled by running conditions of the mother, e. g., by the melatonin level. In the last 10 weeks of pregnancy, phases of quiet (NREM-) and active (REM-) sleep can be differentiated. Pregnancy and intrauterine development are accompanied by considerable changes in breathing and sleep in mother and child, which can be the starting points of pathophysiological developments. Sleep related disorders of breathing (SRDB) in terms of snoring and obstructive sleep apnea syndrome (OSAS) are common in postmenopausal women. But also in the premenopausal period OSAS has a frequency of more than 2 %. Some physiological changes during pregnancy may support the appearance of obstructive SRDB. But younger women with sleep apnea very often do not suffer from typical symptoms of SRDB. Therefore screening questionnaires for SRDB are not very suitable for the detection of sleep apnea in younger women and notably during pregnancy. The prevalence rate of SRDB in pregnancy varies dependent on definitions, methods and the investigated population. At least at the beginning of pregnancy in young women with normal weight snoring and OSAS are rather seldom. Overweight and older age are the crucial risk factors for the appearance of pathological snoring and OSAS at the beginning of pregnancy and for the increase of frequency of SRDB during pregnancy. In the 3rd trimenon the frequency of SRDB increases up to 10 – 30 %. SRDB are supposed to have both a negative impact on morbidity and mortality of the mother and on the fetal outcome. The coincidence of pregnancy and OSAS can result in a variety of pregnancy-related complications both for mother, the unborn respectively the newborn child. Women who snore during pregnancy have an increased risk e. g. for cardiomyopathy, pulmonary embolism, eclampsia and pre-eclampsia. Additionally maternal mortality is increased under these circumstances. With regard to the unborn respectively new born child so called „adverse effects“ may appear e. g. premature birth, an increased rate of caesarean sections, insufficient birth weight respectively unappropriate weight and significantly reduced 1- and 5 minutes APGAR-values. Due to this potential coincidence of pregnancy and OSAS and the negative sequelae both for mother and child, sleep physicians and gynaecologists should increasingly pay attention to this subject.

The multiactinide analysis with accelerator mass spectrometry (AMS) was applied to samples collected from the run 13-05 of the Colloid Formation and Migration (CFM) experiment at the Grimsel Test Site (GTS). In this in situ radionuclide tracer test, the environmental behavior of 233U, 237Np, 242Pu, and 243Am was investigated in a water conductive shear zone under conditions relevant for a nuclear waste repository in crystalline rock. The concentration of the actinides in the GTS groundwater was determined with AMS over 6 orders of magnitude from ∼15 pg/g down to ∼25 ag/g. Levels above 10 fg/g were investigated with both sector field inductively coupled plasma mass spectrometry (SF-ICPMS) and AMS. Agreement within a relative uncertainty of 50% was found for 237Np, 242Pu, and 243Am concentrations determined with the two analytical methods. With the extreme sensitivity of AMS, the long-term release and retention of the actinides was investigated over 8 months in the tailing of the breakthrough curve of run 1...

The potential to provide base-load electricity as well as industrial and domestic heat places geothermal energy in a unique position in the future energy mix. As estimated by the International Energy Agency, geothermal power can contribute to 3.5% to the worldwide power and 3.9% to heat production by 2050. This includes the development of Enhanced Geothermal Systems (EGS) in low-enthalpy systems. The EGS technology is still in an early stage of development and the intended upscaling of power plant capacities presupposes the assurance of efficiency, profitability and safety of geothermal facilities. Pushing EGS technologies towards market maturity requires a long-term strategic approach and massive investments in research and development. Comprehensive multidisciplinary research programs combining fundamental and applied concepts tackling technological, economic and ecological and safety challenges along the EGS process chain are needed. The Karlsruhe Institute of Technology has defined a broad research program on EGS technology development following the necessity of a transdisciplinary approach. Research activities cover the whole process chain including system integration and span from fundamental to applied research across scales. The research concept is embedded in the national research program of the Helmholtz Association and is structured in four clusters: reservoir characterization and engineering; thermal water circuit; materials and geo-processes; and power plant operation. The proximity to industry closely interlinked with fundamental research forms the basis of a target-orientated concept. It combines the disciplines geosciences, geophysics, material sciences, engineering, geochemistry and numerics. The present paper aims at giving an overview of geothermal research at KIT and emphases the need for concerted research efforts at the international level to accelerate technological breakthrough of EGS as essential part of a future sustainable energy system.

Das Lehrforschungsprojekt Gesundheit und Gesundheitsversorgung von Menschen in prekaren Lebenslagen ist eine interdisziplinare fakultatsubergreifende Veranstaltung, die im Modus eines Peer-Learning-Kurses durchgefuhrt wird. Nach einer zweijahrigen Forderphase durch das Universitatsprogramm „Forschendes Lernen“ ist es mittlerweile als regelmasiges Lehrangebot der beteiligten Fakultaten fur Medizin und Sozialwissenschaft verstetigt worden.

In this study, the critical coagulation concentration (CCC) for FEBEX bentonite colloids is determined by colloid coagulation studies under variation of pH, electrolyte concentration, and fulvic acid (GoHy-573FA) content. For CaCl2 electrolyte solution, a pH-independent Ca-CCC of 1 mmol L&minus, 1 is found. In the case of NaCl background electrolyte, a pH-dependent Na-CCC can be determined with 15 &plusmn, 5 mmol L&minus, 1 at pH 6, 20 &plusmn, 1 at pH 7, 200 &plusmn, 50 mmol L&minus, 1 at pH 8, 250 &plusmn, 1 at pH 9, and 350 &plusmn, 100 mmol L&minus, 1 at pH 10, respectively. The addition of 1 mg L&minus, 1 dissolved organic carbon in the form of fulvic acid (FA) increases the Ca-CCC to 2 mmol L&minus, 1. An association of FA with FEBEX bentonite colloids as surface coating can clearly be identified by scanning transmission X-ray microscopy (STXM). The experimental bentonite stability results are described by means of an extended DLVO (Derjaguin&ndash, Landau&ndash, Verwey&ndash, Overbeek) approach summing up hydration forces, short-range Born repulsion, van der Waals attraction, and electrical double layer repulsion. The measured zeta (&zeta, )-potential of the bentonite colloids is applied as platelet face electrokinetic potential and the edge electrokinetic potential is estimated by the combination of silica and alumina &zeta, potential data in the ratio given by the FEBEX bentonite structural formula. Adjusting the montmorillonite face electrokinetic potential by a maximum of &plusmn, 15.9 mV is sufficient to successfully reproduce the measured stability ratios. Due to the uncertainty in the &zeta, potential measurement, only semiquantitative calculations of the stability ratio can be given.

Uranium and thorium decay series disequilibria in deep geothermal brines are a result of water–rock interaction processes. The migratory behavior of radionuclides provides valuable site-specific information and can therefore be an important tool for reservoir characterization and sustainable management of geothermal sites. In this study, we present data from long-term monitoring of naturally occurring 238U, 232Th and 235U series radionuclides analyzed in brine samples collected from the Permo-Triassic sedimentary reservoir rock at the Bruchsal geothermal site (SW Germany). The results show that radionuclides of the elements radium (226Ra, 228Ra, 224Ra, 223Ra), radon (222Rn), and lead (210Pb, 212Pb) are rather soluble in brine, while isotopes of uranium (238U, 234U, 235U), thorium (232Th, 228Th, 230Th), polonium (210Po), and actinium (227Ac, 228Ac) have low solubilities and are mostly immobile. Activities of radium isotopes in the geothermal brine exceed those of their thorium progenitors (average 226Ra = 29.9 Bq kg−1, about 103 times that of its 230Th parent). Modelling the observed disequilibria allows the following conclusion on water–rock interaction processes: (1) supply from alpha-recoil depends on isotope half-life because it is limited by the rate of diffusion through microfractures causing isotopic fractionation. (2) Radium retardation due to adsorption is low (226Ra/222Rn = 1.3) resulting in adsorption–desorption rate constants in the order of 10−10 s−1 for k1 and 10−9 for k2. (3) Scavenging of 226Ra from brine can best be explained by co-precipitation with barite resulting in an observed 226Ra anomaly in the solids of the reservoir section. The precipitation rate constant amounts to ca. 3.4 × 10−8 s−1 corresponding to a mean removal time of radium from brine by mineral precipitation to approximately 1 year. Open-Access-Publikationsfonds 2020

Proceeding investigations of G protein-coupled receptor (GPCR) heterocomplexes have demonstrated that the dopamine D2 receptor (D2R), one of the hub receptors in the physiology of schizophrenia, interacts with both the neurotensin NTS1 (NTS1R) and the serotonin 5-HT2A receptor (5-HT2AR) in cell lines and rodent brain tissue. In situ proximity ligation assay and BRET-based saturation experiments confirmed interacting receptor assemblies in HEK293T and neuronal HT22 cells. The NTS1R agonist NT(8-13) reduces the Gαq-mediated calcium signal in the NTS1R-D2R complex compared to the NTS1R monomer which could be reversed by D2R antagonists. The bivalent ligand CS148 (NTS1R-agonistic, D2R-antagonistic) increased the calcium response addressing the dimer, consistent with the effect of the monovalent ligands suggesting an allosteric D2R-mediated modulation. In contrast, the 5-HT2AR-D2R heteromer did not show a calcium-altering receptor-receptor interaction. Despite their common coupling-preference for Gαq, 5-HT2AR and NTS1R supposedly interact with D2R each in a unique mode. This remarkably diverse ligand-mediated signalling in two different D2R heteroreceptor complexes illustrates the complexity of receptor-receptor interactions and their potential of modifying cell responses to external stimuli. Therefore, GPCR heteromers may provide a very promising novel target for the therapy of neuropsychiatric disorders.

In the frame of studies on the safe disposal of nuclear waste, there is a great interest for understanding the migration behavior of

Phosphoinositide 3-kinase (PI3K) imposes central regulatory signals that promote cell growth, proliferation, motility, and suppression of apoptosis. PI3K is dysregulated in a broad spectrum of human tumours.[1] Considering the central role attributed to PI3K signaling in cancer biology, the success of clinical trials in the field was below expectations, mainly due to metabolic on-target adverse effects. Here, we present a novel, highly selective PI3Kα-covalent inhibitor (compound 19), which combines the exceptional affinity of the pan-PI3K inhibitor PQR514[2] with a linker moiety, directing a warhead to selectively react via a Michael addition with isoform-specific Cys862 of PI3Kα. Cellular assay platforms were combined to validate 19, specifically, to assess its target selectivity and occupancy, and to translate its in vitro activity to cellular readouts. Overall, 19 exhibited excellent cellular activity with a superior profile compared to CNX-1351[3], a previously reported covalent PI3Kα inhibitor. A NanoBRET (Bioluminescence Resonance Energy Transfer) drug-target engagement assay allowed for an investigation of inhibitory efficacy in HEK293 cells. NanoBRET experiments exploiting the Cys862Ser mutant PI3Kα protein confirmed selective reactivity with Cys862. Various cell lines either constitutively activated in PI3Kα (MCF7, T47D, SKOV3) or deficient in PTEN (PC3 and A2058) were used to resolve target engagement, which confirmed a persistent and prolonged suppression of protein kinase B (PKB/Akt, Ser473) phosphorylation after washout of 19 over non-covalent structural analogs thereof that lack a functional warhead. Furthermore, nucleo-cytoplasmic translocation probes based on the FOXO1 transcription factor enabled the investigation of signal propagation downstream of PKB/Akt. In PI3Kα-dependent cell lines, FOXO1, maintained a predominant nuclear localization even after removal of 19, confirming extended PI3Kα targeting upon covalent attachment of specifically this drug. Importantly, 19 provided a considerable gain in potency over BYL719, a clinically approved non-covalent PI3Kα-selective inhibitor. Taken together, our results present a major step towards an increased local and temporal control of PI3Kα signaling through isoform-selective covalent anchoring. This strategy is a step towards the development of drug-like, isoform-selective, covalent PI3K inhibitor scaffolds, and 19 provides a template for the development of PI3Kα inhibitors with overall reduced adverse side effects in cancer therapy. Moreover, our covalent inhibition strategy will pave the way for a better molecular understanding of PI3K isoform signaling in general. [1] Wymann M. P. and Schneiter R. Nat. Rev. Mol. Cell Biol. 2008, 9, 162-176. [2] Borsari, C et. al. ACS Med. Chem. Lett. 2019, 10 (10), 1473-1479. [3] Nacht M et. al. J. Med. Chem. 2013, 56 (3), 712-721. Citation Format: Erhan Keles, Chiara Borsari, Rohitha Sriramaratnam, Thorsten Schäfer, Matthias P. Wymann. A novel, highly potent PI3Kα covalent inhibitor deconvolutes class I PI3K isoforms in cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1378.

The effect of fracture geometry on bentonite erosion for a generic repository site in crystalline host rock environment was investigated by means of 2-d numerical simulations. Fracture geometry was varied systematically using random aperture normal distributions with a mean aperture of 1 mm and standard deviations between 0 and 0.7 mm, respectively. Moreover, two aperture correlation lengths (0.2 m and 2 m) were applied. Based on the synthetic fracture aperture fields generated the cubic law in conjunction with the Darcy equation is used to simulate fracture flow fields for mean flow velocities in the fracture between 1 × 10 −5 m/s and 1 × 10−7 m/s. These flow fields are used in a two-way coupling approach to bentonite erosion simulations. The results of the study clearly show the influence of variable fracture aperture on bentonite erosion behaviour and erosion rates (kg/a). Increasing fracture aperture standard deviation leads to increasing heterogeneous flow velocity distributions governing the erosion behaviour and erosion rates. Calculated steady state erosion rates are in the range of ~0.25 kg/a down to ~0.014 kg/a. The highest erosion rate is calculated for the highest mean flow velocity in conjunction with the highest standard deviation. The effect of aperture heterogeneity diminishes for the lowest flow velocities. In summary, the results show the effect of fracture heterogeneity on bentonite erosion, especially for high to medium mean flow velocities combined with high to medium fracture heterogeneity under the model boundary conditions and model capabilities and limitations considered. An increase of up to ~83% in erosion rate compared to the constant aperture case highlights the need to consider fracture aperture heterogeneity and its effect on the bentonite erosion in the assessment of the safety and evolution of a high-level nuclear waste repository.