RWTH Aachen University

Sorption in shales is a key process controlling their gas storage capacity. It is, however, a complex phenomenon due to the broad and variable petrophysical characteristics of shales. This complexity is further compounded by the simultaneous occurrence of gas adsorption on mineral and organic surfaces and absorption processes within sedimentary organic matter. In this study, gravimetric sorption experiments were conducted on three geologically distinct shales at 40 °C and pressures ranging from 2 to 15 MPa. We examined both pristine powdered shale samples and their solvent-extracted counterparts to investigate the dominant controls and sorption mechanisms of hydrogen (H 2 ) and carbon dioxide (CO 2 ) - two gases central to energy transition. The sorption capacity of H 2 is shown to be independent of the total organic carbon (TOC) content and is rather governed by the available pore volume in the shale, with thermal maturity exerting a positive influence on porosity development, particularly in samples exhibiting contrasting maturities. Conversely, the CO 2 sorption capacity is controlled by both TOC content and available pore volume. An increase in either parameter enhances the sorption capacity. Comparisons of H 2 and CO 2 sorption capacities among samples possessing relatively similar textural properties and contrasting TOC content indicate that the contribution of H 2 absorption in organic matter becomes increasingly significant at elevated pressures, while CO 2 absorption is shown to increase the total sorption capacity at all investigated pressures. This study provides the first experimental evidence on the role of H 2 and CO 2 absorption in increasing the sorption capacity of immature organic-rich shales. • H 2 retention occurs via adsorption, governed mainly by textural properties. • At high pressure and in TOC-rich shales, absorption enhances H 2 sorption. • CO 2 sorption is enhanced by larger textural properties and/or higher TOC content.

• Extend optimal experimental design for guaranteed parameter estimation to LLE systems • Employ rigorous calculations for the LLE using the Baker’s criterion • Avoid problematic parameter values, which may lead to erroneous predictions • Present proof-of-concept case study, reducing the parameter uncertainty by at least 10.3924909 % Semi-empirical models for LLE are essential for chemical process design but rely on experimental data for parameter estimation. In the face of high experimental costs, determining an informative experimental plan is crucial for constructing and validating these models efficiently. OED for (bounded-error) guaranteed GPE is a valuable approach to planning LLE experiments, but it has been limited to systems with simple input-output relations. We extend this method to systems whose input-output relation is implicitly given by an equation system with additional semi-infinite constraints, which corresponds to the rigorous computation of an LLE. Excess Gibbs free energy models are highly flexible but can predict spurious phase splits due to (i) using non-rigorous computations, or (ii) parameter values that are problematic in the sense that they lead to erroneous model behavior. To mitigate these issues in experiment planning, we (i) employ rigorous calculations using Baker’s criterion, and (ii) enforce additional requirements, based on [Mitsos et al. Chem. Eng. Sci., 64(3):548–559, 2009] to exclude parameter values that lead to erroneous model behavior. We solve the resulting problem using (generalized) semi-infinite programming techniques and provide a proof of concept using the Redlich-Kister model to plan the OED to reduce parameter uncertainty. Our approach successfully avoids wrong predictions due to problematic parameter values and computes an experimental design that significantly reduces the predicted parameter uncertainty. However, our method is computationally demanding, necessitating advancements in numerical methods for practical applications involving multiple parameters or more complex excess models.

Combined sewer overflows (CSO) are a significant source of urban water pollution, with sediments originating from sewers contributing substantial loads of organic matter, nutrients, and particulate-associated contaminants to receiving waters. In Germany, constructed wetlands for CSO treatment (CSOCWs) are well-established, yet their large surface area limits their implementation in urban areas. The present study investigates the potential of compact CSOCWs, operated at doubled flow rate, with tailored filter substrates and the addition of biopolymers to enhance treatment performance. A series of flocculation experiments was first conducted to identify a suitable biopolymer for CSO treatment. Subsequently, small-scale pilot column tests were performed to evaluate compact CSOCW configurations. Here, different filter substrates were investigated, including sand, sand-gravel, gravel, shells, sand-activated carbon, and sand-zeolite, with and without the selected biopolymer introduced into the inflow to assess its effect on treatment performance. Results show that compact CSOCWs with suitable substrates and increased flow rates achieved removal efficiencies comparable to the reference CSOCW in standard operation, exhibiting only minor deviations. Sorptive and fine-grained substrates (activated carbon, zeolite) demonstrated high performance for particulates, COD, DOC, and NH4N, respectively. Biopolymer dosing significantly enhanced particle and COD retention in coarse filter substrates (gravel, shells), thereby reducing performance differences across configurations. In contrast, phosphorus removal remained limited across all configurations, independent of biopolymer dosing. These findings demonstrate that compact CSOCWs can provide a robust treatment option for CSOs and urban runoff under increased hydraulic loading, particularly in densely populated areas.

Words and sentences can be used to carry out a wide range of different communicative actions. Recognizing these actions quickly is crucial for effective understanding. Previous research indicates that communicative action understanding is a rapid process, as brain signatures of different communicative actions differ within ca. 250 ms following the relevant linguistic information. However, previous work has explored a restricted set of communicative actions, leaving other ones still unexplored. In the present study, we examine emotion-related utterances in the 1st person singular ("I am happy"), which are typically applied to express an emotional state of the speaker, that is, to perform so-called a 'expressive' communicative action. We recorded brain potentials while subjects read such 'expressive sentences' and similar ones in the 3rd person singular, which are likely applied to assert or report facts ("he is happy"). Further assertive control past-tense sentences were included to control for any 1st/3rd person differences. Brain responses to sentences with expressive communicative actions differed from those to assertives 221-270 ms after the critical sentence-final word appeared, and an even earlier dissociation was observed. These results extend previous findings from contrasting assertive and directive communicative actions by demonstrating that the brain is quick in discriminating between communicative actions, therefore suggesting a generalizable temporal pattern. Since communicative action is processed fast, within ca. 250 ms after the critical utterance-related information is presented, our results are consistent with parallel models of language processing stating that pragmatic processing occurs rapidly and near-simultaneously with that of semantic and morphosyntactic information.

• A strong correlation was found between the representative cooling rate of eutectoid phase transformation and the characteristics of the pearlite matrix in a fully pearlitic ductile cast iron. • The yield limit found to be strongly dependent on the interlamellar spacing of the pearlite matrix, following a modified Hall-Petch relationship. • In regions of higher strain, the graphite morphology is the dominant factor influencing mechanical properties under static loading. • Microstructure-informed simulation provides insights into how interlamellar spacing affects yield strength, highlighting the crucial role of pearlite fineness in yielding behavior. Microstructural features of ductile cast iron (DCI), including graphite morphology and the pearlitic matrix, are influenced by solidification and subsequent eutectoid transformation and can be effectively tailored through the cooling conditions. While the relationship between pearlite characteristics and mechanical properties is well established for pearlitic steels, the specific contribution of the pearlitic matrix to the mechanical response of DCI has received limited attention. In this study, fully pearlitic DCIs were cast under various cooling rates between 0.1 to 0.34 K/s, enabling systematic variations in microstructure to be correlated with changes in mechanical properties. The resulting interlamellar spacing (ILS) of the pearlite matrix ranged from 291 to 564 nm and was associated with an approximately 70 MPa difference in yield strength. A modified Hall-Petch-type relationship was formulated to describe the dependence of yield strength on ILS. To support predictive capability, representative volume elements were generated from optical micrographs and micromechanical simulations were conducted to isolate the effect of varying ILS on yield strength. The simulation results showed excellent agreement with the experiments, confirming that the ILS predominantly governs the onset of plastic deformation and that pearlite refinement is a key controlling factor for the yield strength of pearlitic DCI.

Grid-following (GFL) and grid-forming (GFM) inverters are usually synchronized with the phase-locked loop and the power synchronization control respectively, and they exhibit complementary characteristics on the grid strength adaptability. How to make the best of two synchronization approaches and endow the system with superior grid strength adaptivity and transient stability, remains a significant yet unsolved challenge. Based on their structural similarity and duality, this paper proposes a family of novel integrated synchronizations, which are in a symmetric and elegant form. The interaction between the integrated synchronization and other control parts is described by evolving the complex system into a simple single-input-single-output model. On its basis, comprehensive small-signal and transient stability analysis reveals that the proposed synchronization methods can ensure the robust operation of inverters and enhance their tolerance to severe faults.

Detection of antibodies in allergy diagnostics requires allergens to be immobilized, e.g., on microtiter plates; thereby, immobilization without capturing antibodies remains a challenge. An immobilization platform, based on the material-binding peptide Snakin-1, addresses the outlined challenge for ELISA-based allergy detection on the example of Bet v 1 from birch pollen. Bet v 1 from birch pollen is the main cause of allergic rhinitis in Europe. Snakin-1 was selected among five material-binding peptides due to its polystyrene (PS)-binding properties, productive immobilization in a fusion protein with Bet v 1, and lack of interference with the primary and secondary antibody of the assay. The developed ELISA covers the whole range of antibody detection in diagnostics of the anti-Bet v 1 antibody. The reached sensitivity of the Bet v 1-Snakin-1 ELISA on standard PS plates is comparable to the Bet v 1 signal on high-binding PS plates, and the Bet v 1-Snakin-1 ELISA outperforms the Bet v 1 ELISA on high-binding plates (1.3-fold). SPR measurements of binding Bet v 1 and Bet v 1-Snakin-1 to PS, as well as subsequent antibody detection, confirm the role of Snakin-1 in productive immobilization of the Bet v 1 allergen on PS. The necessity to block the microtiter plate with BSA could be omitted, and a detection limit of at least 0.333ng/mL (0.14 kU/L) sIgE in serum was achieved. The latter results make the scalable coating of allergens on untreated PS plates from aqueous solutions, in combination with ELISA, a highly attractive platform for allergy diagnostics.