RWTH Aachen University

In 1962, Martin Kruskal coined the term “asymptotology”. As it is known, asymptotic methods, the essence of which is the study of phenomena in limiting cases, are at the heart of natural sciences of nature. It is now a well-developed part of pure mathematics, closely related to applied mathematics. Kruskal, in his lecture, drew the attention of the audience to the fact that, for all the diversity of asymptotic methods, it is possible to identify some common features in them and study them on their own, regardless of the objects to which they are applied. Such meta-science should constitute the subject of asymptotology. It is necessary to say directly that over the past 60 years such ideology, although it attracted (and still attracts) certain attention, has not become mainstream. Does this mean that Kruskal's idea is currently of purely historical interest? It should be emphasized that we are talking about asymptotology as a kind of meta-science. Asymptotic methods as the most important tool of scientific analysis are not threatened by Big Data and AI. In this paper we tried to analyze the opinions of prominent users of asymptotic methods about the future of asymptotology.

Intestinal disorders and vascular calcification (VC) are often associated with chronic kidney disease (CKD). While gut barrier alterations have been reported in CKD (such as abnormal intestinal permeability, bacterial overgrowth, and inflammation), it is not clear if vascular calcification influences these alterations. To investigate whether the bidirectional relationships between VC and gut dysfunction could be mediated by increased inflammation and uremic toxin generation, we used the SNx‐VC model of uremic vascular calcification (rats undergoing subtotal 5/6th nephrectomy and fed a procalcifying high‐phosphate and vitamin D diet). We confirmed the presence of CKD and VC by von Kossa staining and observed increased gut‐origin uremic toxin, indoxyl sulfate (IS), in SNx‐VC animals compared to controls. In SNx‐VC rats, we observed decreased mucus production (Alcian blue, Mucin 2 staining) in the colon and ileum which was correlated with the level of calcification. There was no change in inflammation markers or tight junction protein expression. We assessed intestinal levels in the NOD‐like receptor family pyrin domain containing 6 (NLRP6) protein, known to regulate mucus secretion, and found no change in the colon or ileum. Nlrp6 mRNA was, however, decreased in the colon of SNx‐VC rats, along with other mRNA (Ly96, Sod1), while Tlr2 was increased compared to controls. Our observations of low mucus, low Nlrp6 mRNA, and high IS in SNx‐VC rats confirm a link between gut barrier alterations and uremic VC. This suggests that alterations in the mucus layer could favor the generation of gut‐origin uremic toxins and promote VC in CKD. Thus, improving the gut mucus barrier function in the context of uremic VC could be considered as a possible therapeutic strategy in CKD patients.

We consider a variational model for heterogeneous phase separation, based on a diffuse interface energy with moving wells. Our main result identifies the asymptotic behavior of the first variation of the phase field energies as the width of the diffuse interface vanishes. This convergence result allows us to deduce a Gibbs–Thomson relation for heterogeneous surface tensions. Proceeding from this information, we prove that (weak) solutions of the Allen–Cahn equation with space dependent potential converge to a BV solution of weighted mean curvature flow, under an energy convergence hypothesis. Additionally, relying on the relative energy technique, we establish a weak-strong uniqueness principle for solutions of weighted mean curvature flow.

Laser powder bed fusion is a cornerstone technology for additive manufacturing (AM) of metals and polymers, yet challenges in achieving consistent reproducibility and process optimization persist. Addressing these requires a systematic understanding of the interactions between feedstock, process parameters, and final part characteristics throughout the entire production chain. This study presents results from a comprehensive interlaboratory investigation conducted by 32 research institutions, evaluating six feedstock, including nanoparticle‐modified aluminum alloy and polyamide powders, under standardized protocols. Data analysis encompasses 69 powder properties, 15 process parameters per print, and 78 part features, culminating in a dataset of over 1.2 million correlations. Advanced statistical methods and machine learning are employed to identify critical variability drivers, such as the impact of nanoparticle modifications on powder flowability and thermal conductivity, as well as the influence of process parameters on reproducibility. Newly introduced dimensionless figures of merit provide universal metrics to describe and predict thermal and mechanical interactions, simplifying process optimization and material characterization. The findings, supported by an open‐access dataset adhering to findable, accessible, interoperable, and reusable principles, advance understanding of material–process–structure–property relationships. They establish a benchmark for future research and lay the foundation for improving the reliability, quality, and sustainability of AM processes.

We propose a novel approach for modeling chemical reactions within the particle-based Fokker–Planck framework for gas flow simulations which conserves mass, momentum, and energy while retaining the performance advantages of the Fokker–Planck approach over the Direct Simulation Monte Carlo (DSMC) method in areas of high density. We show an application of the approach to recombination and exchange reactions, discuss verification results, and demonstrate performance advantages when compared to DSMC for applications in low Knudsen number regimes. The developed method can be applied to simulation of flows in the continuum and transitional regimes as well as to multi-scale coupled Fokker–Planck-DSMC simulations.

Introduction: The concept of oncological communication skills training (CST) has already proven to be effective and has been incorporated into the relevant guidelines. The current status of CSTs in Germany is unclear. Methods: We approached all oncology centers in Germany certified by Deutsche Krebsgesellschaft (DKG) and investigated quantitative and qualitative aspects of CST programs in a mixed-methods approach using questionnaires and interviews. Results: Only a quarter (23.7%, n = 18/76) of the responding centers demonstrated a regular CST. These CSTs were partially congruent with the consensus recommendations while deviating significantly in other areas, such as duration, scope, and course content. We asked centers that do not offer CST or do not offer fully satisfactory CST (respondents n = 60) for factors that hinder successful implementation, which were identified as, e.g., scarce time and personnel resources (92%), no counterpart funding (27%), lack of appreciation (25%) and knowledge about the concept (3%), organizational obstacles (22%), and low prioritization (12%). Steps that could facilitate nationwide implementation were found, such as support for implementation through concrete instructions (27%), mandatory participation (20%), an active management level in the question of responsibility (17%), inclusion in the certification criteria for oncology centers (12%), and an integration into the Weiterbildungsordnung (WBO, specialist training guideline) (10%). Conclusion: Although previous studies have shown that CSTs have positive effects, sufficient implementation has not yet been achieved across the board in Germany. Individual starting points have been identified; further efforts are needed to advance this goal.

Future problems request the development of materials, which serve as components in technologies addressing these challenges. In this context, tellurides are of great interest since many members of that remarkable family of solids are at the frontline of fundamental research and technological applications. The tailored design of novel tellurides showing task-specific features also demands a proper understanding of their electronic structures, as the knowledge of them provides invaluable insights into the materials characteristics. Therefore, it will be quite helpful if there is a fundamental design principle that allows us to plan electronic peculiarities in tellurides in a straightforward manner. Eventually, the Zintl−Klemm−Busmann idea is a recipe that can guide us through electronic structures based on the corresponding crystal structures and it has been applied to several tellurides to date; yet, how helpful is that approach with regard to the prediction of electronic peculiarities for tellurides in general? In the framework of this review, it will be the overall goal to answer that question.

A series of manganese complexes derived from (imino)phenol/pyridine proligands have been synthesized, structurally characterized and used as catalysts in the ring‐opening polymerization (ROP) of rac‐lactides (rac‐LA). Reactions of MnCl2·4H2O salt with 2‐[((2‐hydroxyethyl)imino)methyl]phenol (L1H2) afford a tetranuclear Mn(III) complex [Mn(L1)Cl]4 (Mn1). Separately, treatment of MnCl2·4H2O with 2‐[((2‐methoxyethyl)imino)methyl]phenol (L2H) gave the mononuclear Mn(II) complex [Mn(L2)2(CH3OH)2] (Mn2). Further, reactions of (imino)pyridine proligands ((E)‐2‐((pyridine‐2‐ylmethylene)amino)ethan‐1‐ol (L3H) and (E)‐N‐(2‐methoxyethyl)‐1‐(pyrid‐2‐yl)methanimine (L4)) with MnCl2·4H2O afforded polynuclear Mn(II) complexes [Mn(L3H)Cl2]3 (Mn3) and [Mn(L4)Cl2]3 (Mn4), respectively. The molecular structure of Mn1 established the tridentate binding mode of the dianionic alkoxy‐(imino)phenol proligand ((L1²⁻)) through the phenoxo and pendant‐arm alkoxy‐oxygen and the imine‐nitrogen atoms. In contrast, the molecular structure of Mn2 showed that the ether‐(imino)phenol pro‐ligand (L2H) is monoanionic (L2⁻) and bidentately coordinated to the Mn(II) metal center through the phenoxo‐oxygen and the imine‐nitrogen atoms. The dinuclear complex Mn3 contains a neutral N^N bidentately bound proligand (L3H). All the complexes (Mn1–Mn4) formed active catalysts in ROP of rac‐LA with the propagation rate constant kp of up to (4.25 ± 0.15) × 10⁻² L mol⁻¹ s⁻¹. The polymers obtained were atactic biased (Pr = 0.55–0.59), produced with moderate control over average‐number molecular weights and were moderately dispersed (Đ up to 1.8) under melt conditions.

We propose a variant of the shortest path problem where the order in which vertices occur in the path is subject to precedence constraints. Precedence constraints are defined in terms of vertex pairs (a,b)$\left(a,b\right)$ which indicate that a vertex a a is the predecessor of a vertex b b . A feasible (not necessarily simple) path may visit a vertex only upon having covered all its predecessors. The problem generalizes the graphic TSP Path, which makes it APX‐hard. We propose a dynamic program and identify input classes for which the dynamic program yields an optimal solution in polynomial time. We also explore the limits of efficient solvability by proving that the problem remains hard even when significantly restricting the structure of the graph or the structure of the precedence constraints: Surprisingly, the problem remains hard even when restricted to spiders.

Background & Aims Cholangiocarcinoma (CCA) displays remarkable anatomical and histological heterogeneity. Besides diagnosis confirmation, histology currently does not have a major role in the management of CCA. We aimed to study the clinical relevance of histological heterogeneity of CCA and putative tissue biomarkers by creating a multicentric digitalized European CCA Histology Registry. Approach & Results Nine referral centers, participating in the International Cholangiocarcinoma clinical registry, shared samples and data from 293 patients. Histological and immunohistochemistry stains (n=10) were performed. Computed tomography (CT) scans (n=112 cases) were analyzed by morphological and radiomics techniques. A selection of cases (n=18) was processed for spatial transcriptomics analysis. No significant differences in 5-year overall survival (OS) were found in perihilar CCA vs intrahepatic (i) CCA, and in Small Bile Duct (SBD) vs Large Bile Duct (LBD) iCCA. When cases were classified by periodic acid of Schiff (PAS) positivity (mucin content), PAS HIGH LBD iCCA showed a significantly worse 5-year OS compared to PAS LOW iCCA. Multivariate Cox regression identified PAS HIGH LBD iCCA phenotype as an independent predictor of a worse OS. PAS HIGH LBD iCCA subtype showed specific molecular characteristics at spatial transcriptomics and immunohistochemistry; CT scans and serology could distinguish PAS HIGH LBD iCCA phenotype with excellent accuracy. Conclusion Our data underline the importance of identifying morphological subclasses with a significant prevalence in CCA as a tool for risk stratification and prognosis. The European CCA Histology Registry represents a valuable platform for integrating digital pathology with clinical, radiological, and molecular information as a framework for digital twin advancement.

DNA-encoded libraries (DELs) are useful for hit discovery in the pharmaceutical industry. Although a large number of individually coded molecules are accessible through DELs, their structural diversity is limited because few transformations are benign and chemoselective enough to be applied in the presence of DNA in aqueous environments. In particular, C–H functionalization chemistry that could be ideally suited to increase structural diversity through late-stage functionalization is currently absent from DEL synthesis. Here we present a general C–H functionalization of electron-rich arenes on DNA. The development of a selenoxide reagent is key to achieving the regio- and chemoselective formation of arylselenonium salts in aqueous media. The introduction of arylselenonium salts offers a versatile linchpin on DNA conjugates, which gives access to a multitude of analogues through diverse subsequent reactions, including transition-metal-mediated and photochemical transformations for the formation of C–C, C–I and C–S bonds.

In underground hydrogen storage operations, reservoir rocks often experience periodic pore pressure fluctuations due to annual or more frequent gas extraction and injection cycles. These fluctuations subject the reservoir rocks to cyclic effective stress changes, causing their mechanical and transport behaviors to differ from those under static conditions. However, understanding how porous rocks react to cyclic loading conditions is still limited. To bridge previous research gaps, cyclic loading tests were conducted on Castlegate and St Bees Sandstone, with applied stress amplitudes ranging from 70 to 90% of their monotonic peak strength. This experimental approach was designed to replicate the in situ stress conditions experienced by reservoir rocks during gas operations. Concurrently, we utilised the steady-state method to measure permeability changes under cyclic loading. By comparing the micro-CT features of the sandstones before and after cyclic loading tests, we quantitatively analysed the microscopic mechanisms driving these alterations in sandstone samples. Our results show that under cyclic loading conditions, the inelastic axial strain and Young’s Modulus initially increase for both sandstones, with the most significant changes occurring within the 1st cycle, followed by a trend towards stability. Permeability decreases with increasing stress and loading cycles. For the Castlegate Sandstone, elevated confining pressure intensified permeability loss, while in St Bees Sandstone, high confining pressure resulted in less permeability loss compared to low confining pressure, which was related to shear band development. Microstructural analysis showed grain movement, rotation, and rearrangement in Castlegate Sandstone under external forces, leading to pore/throat compression and reduced porosity/permeability. In contrast, St Bees Sandstone microstructure changes under low stress involved grain cracking from shear dilatancy, increasing porosity but blocking throats, complicating pore structure, then reducing permeability. Under high confining pressure, the strength of St Bees Sandstone rose without sufficient differential stress for shear dilatancy. Decreased permeability and pore volume were linked to compaction-dominated deformation.

Designing optoelectronic devices based on cesium lead chloride (CsPbCl3) perovskites requires accurate values of their optical constants. Unfortunately, experimental data for this material are limited thus far. Here, we applied spectroscopic ellipsometry (SE) to measure the complex optical constants of thermally evaporated CsPbCl3 thin films on Si/SiO2 substrates. An optical dispersion model was developed, where necessary parameters were extracted by employing Tauc–Lorentz in conjunction with two harmonic oscillators. The extinction coefficient spectrum exhibited a sharp absorption edge at 411 nm. The optical bandgap was calculated as ∼2.99 eV as consistent across SE and absorption data. This work provides fundamental insights for designing CsPbCl3-based optoelectronic devices.

A classical coulombic correlation functional in one-loop (1L) and local-density-approximation (LDA) is derived for electrolyte solutions, starting from a first-principles many-body partition function. The 1L–LDA functional captures correlations between electrolyte ions and solvent dipoles, such as screening and solvation, which are ignored by conventional mean-field theories. This 1L–LDA functional introduces two parameters that can be tuned to the experimental dielectric permittivity and activity coefficients in the bulk electrolyte solution. The capabilities of the 1L–LDA functional for the description of metal–electrolyte interfaces are demonstrated by embedding the functional into a combined quantum–classical model. Here, the 1L–LDA functional leads to a more pronounced double-peak structure of the interfacial capacitance with higher peaks and shorter peak-to-peak distance, significantly improving the agreement with experimental data and showing that electrolyte correlation effects exert a vital impact on the capacitive response.

Aiming at challenges posed by rock freeze-thaw (FT) in cold regions rock mass engineering, it is of great significance to analyze its macro- and micro-mechanical properties and damage laws for the smooth progress of construction. In this study, indoor freeze-thaw cycle (FTC) tests on sandstone were conducted to analyze the mass change rate, density change rate, longitudinal wave velocity change rate, microstructure change and mechanical properties of sandstone after FTC. A microscopic FT damage variable reflecting the FT damage was defined based on the changes of rock porosity before and after the FTC, enabling the derivation of the total damage variable under the coupled action of FTC and mechanical loading. A damage evolution equation and a microscopic damage constitutive model for rock under coupled FTC and confining pressure were established by using Lemaitre’s strain equivalence principle, the theory of continuous damage mechanics, and the assumption that the failure of rock micro-units follows the SMP criterion. The rationality and accuracy of the model were verified using triaxial compression test data for FT-damaged rock. The results show that both macro- and micro- mechanical properties of sandstone are degraded under the action of FTC, resulting in significant damage. The developed microscopic damage constitutive model can reflect the stress-strain characteristics of the whole process of FT rock triaxial compression, with excellent agreement observed between experimental and theoretical curves. This validates the reliability of the model and the methodology for determining its parameters. Additionally, defining the microscopic FT damage variable based on rock porosity changes is demonstrated to be a feasible and highly accurate approach to reflect rock FT damage degree. This model expands the damage model for rock under the coupling effect of FTC and confining pressure, further illuminating the damage mechanism and failure law in such environments. The findings provide references for the construction of rock mass engineering in cold regions.

The transition from an autotrophic to a heterotrophic lifestyle is associated with numerous genomic changes. These often involve large genomic alterations, potentially driven by repetitive DNAs. Despite their recognized role in shaping plant genomes, the contribution of repetitive DNAs to parasitic plant genome evolution remains largely unexplored. This study presents the first analysis of repetitive DNAs in Hydnoraceae genomes, a plant family whose members are holoparasitic. Repetitive DNAs were identified and annotated de novo. Abundant transposable elements and 35S ribosomal DNA in the Hydnora visseri genome were reconstructed in silico. Their patterns of abundance and presence–absence were individually and comparatively analyzed. Both Hydnoraceae genera, Hydnora and Prosopanche, exhibit distinct repeatome profiles which challenge our current understanding of repeatome and rDNA evolution. The Hydnora genomes are dominated by long terminal repeat retrotransposons, while the Prosopanche genomes vary greatly in their repeat composition: Prosopanche bonacinae with a highly abundant single DNA transposon and Prosopanche panguanensis with over 15% 5S rDNA, compared to ≤ 0.1% in the Hydnora genomes. The repeat profiles align with the phylogeny, geographical distribution, and host shifts of the Hydnoraceae, indicating a potential role of repetitive DNAs in shaping Hydnoraceae genomes to adapt to the parasitic lifestyle.