[FeFe] hydrogenases are Nature's most efficient catalysts for the cleavage and evolution of molecular hydrogen. Despite decades of research, key aspects of the catalytic cycle and the underlying geometrical and electronic properties of the active-site cofactor, called the H-cluster, are not fully understood. Spectroscopic techniques have played a central role in establishing the current state of knowledge on [FeFe] hydrogenases, and further advances in the field depend critically on novel techniques that yield so-far inaccessible insights into structural and mechanistic aspects. Infrared (IR) absorption spectroscopy represents a well-established and versatile technique that can identify and characterize all active and inactive states of the H-cluster by means of structurally sensitive and spectrally isolated CO and CN stretching vibrations. However, the amount of information that can be extracted from these linear experiments is inherently limited. Here we introduce experimental and computational two-dimensional (2D-)IR spectroscopy for the characterization of [FeFe] hydrogenases. Utilizing the Hinact state of the H-cluster as a model system, we demonstrate that this nonlinear technique yields direct information about the nature and interactions of the CO and CN stretching vibrations. These insights allow, for the first time, to quantitatively describe the character of these widely used reporter vibrations, their spatial localization, and the way they change upon structural variation of the H-cluster. The strength of this approach is demonstrated by correctly identifying the proposed structure of the Hinact state, in solution and at ambient temperature. In conclusion, the introduced combination of experimental and computational 2D-IR spectroscopy represents a powerful approach for studying [FeFe] hydrogenases and other complex organometallic targets.

In this paper we study the optimal control of a class of semilinear elliptic partial differential equations which have nonlinear constituents that are only accessible by data and are approximated by nonsmooth ReLU neural networks. The optimal control problem is studied in detail. In particular, the existence and uniqueness of the state equation are shown, and continuity as well as directional differentiability properties of the corresponding control-to-state map are established. Based on approximation capabilities of the pertinent networks, we address fundamental questions regarding approximating properties of the learning-informed control-to-state map and the solution of the corresponding optimal control problem. Finally, several stationarity conditions are derived based on different notions of generalized differentiability.

A dinuclear copper(I) complex Cu2L22 (L2 = 3,3-dimethyl-1-(1-methyl-1H-benzo[d]imidazole-2-yl)-N-(propan-2-ylidene)butan-2-amine) containing benzimidazole and imino donors was previously reported by some of us as an efficient catalyst for the aerobic oxidation of alcohols to aldehydes in presence of TEMPO (2,2,6,6-tetramethylpiperidinyloxyl) and an external base NMI (N-methyl imidazole). Cu(III)2(bis-μ-oxo) and Cu(II)2(bis-μ-hydroxo) cores were trapped as viable intermediates in the reaction, which provided deeper mechanistic insights. Here, we report two new ligand systems L3 (N-isopropyl-3,3-dimethyl-1-(1-methyl-1H-benzol[d]imidazole-2-yl)butane-2-amine) and L4 ((Z)-2,4-di-tert-butyl-6-(((3,3-dimethyl-1-(1-methyl-1H-benzol[d]imidazole-2-yl)butane-2-yl)imino)methyl)phenol), which are designed to perturb the overall electronics of the complexes and the resulting effects on their O2 activation mechanisms. The stronger donation of the secondary amine group stabilizes a mononuclear CuIL3 core, which nevertheless follows a dinuclear O2 activation mechanism as in Cu2L22. Notably, the CuIL3/TEMPO catalyst system performs the aerobic oxidation of alcohols to aldehydes with good yields and turnover numbers, even in the absence of NMI. The dinuclear CuI2L42 complex involving a non-innocent phenolate group, in contrast, exhibits depleted catalytic activity, because of the instability of the Cu(III)2(bis-μ-oxo) core against intramolecular H-atom abstraction to form an alkoxo bridged dicopper(II) complex.

The development of immunocompetent skin models marks a significant advancement in in vitro methods for detecting skin sensitizers while adhering to the 3R principles, which aim to reduce, refine, and replace animal testing. This study introduces for the first time an advanced immunocompetent skin model constructed entirely from induced pluripotent stem cell (iPSC)-derived cell types, including fibroblasts (iPSC-FB), keratinocytes (iPSC-KC), and fully integrated dendritic cells (iPSC-DC). To evaluate the skin model’s capacity, the model was treated topically with a range of well-characterized skin sensitizers varying in potency. The results indicate that the iPSC-derived immunocompetent skin model successfully replicates the physiological responses of human skin, offering a robust and reliable alternative to animal models for skin sensitization testing, allowing detection of extreme and even weak sensitizers. By addressing critical aspects of immune activation and cytokine signaling, this model provides an ethical, comprehensive tool for regulatory toxicology and dermatological research.

This article examines the condition of hybrid sovereignties in unstable borderlands characterised by conflict, crime and cross-border mobility as well as the competition and collusion between violent non-state actors and state authorities. While in political practice open borders are often associated with mobility (of people), closed borders are imagined as guarantors of security (of nation-states). This dichotomy, however, ignores porosity as a third dimension. The article theorises the link between the porosity of borders and complementary governance constellations and discusses its implications for hybrid sovereignty. We illustrate our argument with insights from the Colombian-Venezuelan borderlands.

This article investigates how social inequality is reproduced through the recontextualization of mathematics pedagogy, using Dowling’s social activity method as an analytical framework. The study identifies the selection and transmission of pedagogic messages as a potential pathway. Findings indicate that teachers in upper-stream schools favour abstract, context-independent messages and metonymically organize tasks to maintain their messages in esoteric mathematical domain. In contrast, their middle- and bottom-streams counterparts often select everyday, context-dependent tasks and assemble tasks metaphorically, limiting students’ access to the abstract mathematical system. These results suggest that class differences are transformed and legitimized through the differential selection and transmission of pedagogic messages, shaping students’ social consciousness in different ways and perpetuating social stratification.

Type 2 inflammation is an essential defense mechanism of the innate and adaptive immune systems, but when dysregulated, it can cause chronic atopic diseases like allergic asthma and atopic dermatitis. Thymic stromal lymphopoietin (TSLP) helps drive type 2 inflammation by guiding T cells toward a type 2 helper cell (TH2) subtype and stimulating B cells’ antibody production. Fibronectin (FN) has recently been found at elevated levels in the plasma of children with atopic dermatitis and shown a potential proinflammatory role in bronchial epithelium tissue models. Both proteins’ surface charges suggest potential interaction with charged molecules. Seeking new strategies against type 2 inflammation, we found that negatively charged polyglycerol sulfates strongly bind to TSLP and FN. We confirmed that these molecules inhibit inflammation by reducing the TSLP-mediated type 2 polarization of CD4+ T cells. We found that adding polyglycerol sulfate to FN-triggered inflamed bronchial epithelium models reduced TSLP expression and interleukin 6 secretion.

Advancing cancer research depends significantly on developing accurate and reliable models that can replicate the complex tumor microenvironment. Tumor spheroids─three-dimensional clusters of cancer cells─have become crucial tools for this purpose. The overarching goal of tumor spheroid culture is to develop biomaterials that mimic the dynamic mechanical behavior of the native extracellular matrix, enabling high-fidelity culture models. In this study, we developed dynamic hydrogels based on dual-dynamic covalently cross-linked polyglycerol, using boronate bonds and Schiff-base interactions. In addition to good biocompatibility and long-term stability, the hydrogels showed tunable mechanical properties that enabled cells to actively remodel their surrounding microenvironment. This platform was used for successful 3D culture of various cancer cell lines, including HeLa, A549, HT-29, BT-474, and SK-BR-3, which were encapsulated in situ and formed 3D tumor spheroids. These results demonstrate the feasibility and versatility of our dynamic hydrogel system in supporting tumor spheroid culture.

The cyanobacterium Aetokthonos hydrillicola has recently become famous as the “eagle killer”, producing the biindole alkaloid aetokthonotoxin (AETX), a pentabrominated neurotoxin causing the wildlife disease vacuolar myelinopathy. HPLC-HRMS2 analysis of extracts from environmental samples of the cyanobacterium revealed the presence of AETX derivatives and biosynthetic intermediates of the cyanobacterial neurotoxin. Mass spectrometry-based molecular networking and other advanced computational data mining techniques were employed to explore the chemical space of natural AETX derivatives. We identified a total of 43 biosynthetic intermediates and derivatives of AETX, including several iodinated derivatives, a rare halogenation in specialized metabolites of freshwater organisms. Structural characterization of these metabolites showed that most of them are AETX derivatives with varying substitution patterns of the bromo or iodo substituents, but also, AETX biosynthetic intermediates and other biindole derivatives were detected. Cytotoxicity assays of two isolated derivatives and AETX showed that they differ markedly in their activity.

We present VeRidium, a fully immersive and interactive virtual reality environment for the utilization in university-level teaching. In a comparative study, one cohort of students was revisiting the fundamental structures of the metals in the virtual environment, another cohort was given the same tasks with clay models. Pre-Post-Test analyses reveal the efficacy and strengths of the virtual environment despite a larger preparational effort. Some lessons-learned are given from our journey starting with the programming of the environment from scratch, to final upload in the app store and implementation in lecture halls.

In many valuations, the cost of equity is determined on the basis of the CAPM. The dominating instrument for estimating the beta factor within this framework is the so-called Market Model. As far as the own beta of the valuation object is concerned, the reliability of the data available for this purpose is often questioned and an alternative tool, in particular a peer group beta, is used. The following article identifies types of data bias that do not affect the outcome of beta estimation – both for an individual company and for a peer group. The results urge caution against a hasty rejection of the object beta and an almost automatic use of peer group betas.

We report the synthesis of a fluorescent polycyclic aromatic hydrocarbon dye with a “symmetry-broken” core, derived from the related hexa-peri-benzocoronene (HBC) core with a fluoranthene subunit. The fluorophore is composed of a pure carbon skeleton without heteroatoms and exhibits remarkable photoluminescence properties with a photoluminescence quantum yield (PLQY) of up to 67% in toluene, exceeding that of the parent HBC by a factor of 30. The single crystal X-ray structure reveals the distorted polycyclic aromatic hydrocarbon structure, which is responsible for the optoelectronic properties, as supported by density functional theory calculations. We show that the new fluorescent dye can be readily used for the fabrication of organic light-emitting diodes (OLED) without extensive optimization, whereby solubility in a variety of solvents and successful film formation are decisive.

For enhancing the performance of electric double-layer capacitors, the porous electrodes must be further optimized. While many studies on electrolyte and electrode structures enable detailed insights, the length of the pore channels of the electrode has been overlooked. Here, we use films of two-dimensional conductive metal–organic frameworks, where the film thickness (and thus the pore channel length) is rationally tuned over a wide range. Cyclic voltammetry experiments with two different electrolytes were conducted, revealing the charge transport kinetics in the porous electrodes. For the highly mobile electrolyte, the kinetics is not limited by ion transport (i.e., diffusion) even for thick films, exhibiting mainly surface-controlled kinetic behavior. In contrast, for the less mobile electrolyte, the kinetics is primarily limited by ion diffusion, and the pore channel length has a severe impact, where long channels result in strongly decreased capacitances, highlighting the importance of adjusting the channel length.

Basándonos en el análisis de las novelas Dos veces junio (Martín Kohan, 2002) y El desierto (Carlos Franz, 2005), este artículo examina la representación ficcional de los regímenes totalitarios. Ambas obras pueden analizarse con el trasfondo del llamado giro victimario; su particularidad es que están narradas desde la perspectiva de los perpetradores o de sus cómplices. Sobre el trasfondo de esta observación, se introduce el concepto del narrador cómplice, que implica una estrategia específica de emocionalización del público lector.

There is evidence that judges evaluate auditor effort with hindsight bias, overestimating the likelihood that the auditor has not met the standard of due care. In an analytical analysis, this paper shows that auditors will rationally anticipate judges’ hindsight bias and will thus likely exert excessive effort in the first place. Furthermore, the paper shows that, counterintuitively, (a) capping liability and (b) lowering the standard of due care to gross negligence are generally not helpful remedies to efficiently counteract hindsight bias. Indeed, a debiasing strategy intended to mitigate judges’ hindsight bias, such as by providing appropriate training, may actually cause excessive auditor effort. However, if the legislator tightens the standard of due care sufficiently, this will provide efficient incentives. At the same time, tightening the standard of due care is not a suitable remedy for a different form of hindsight bias, which induces a judge to find the auditor's behaviour reckless and to award punitive damages. Consequently, the proper design of remedies to mitigate the effects of judges’ hindsight bias depends on whether or not punitive damages are allowed.

Addressing the global biodiversity crisis requires conservation engagement across generations. However, generational amnesia and extinction of experience probably threaten this effort, reflecting declines in nature knowledge, experience and engagement among younger generations. We examined urban green area visit frequency, nature-relatedness, identification skills and familiarity with species (plants, birds and butterflies) and pro-conservation behaviour intentions in adolescents (15–17 years, mean = 15.97), young adults (18–29 years, mean = 23.72) and older adults (> 30 years, mean = 40.54) in Germany. With a path analysis, we explored relationships between concepts across all age groups. Although all age groups visited green areas similarly, identification skills, nature-relatedness and intentions declined progressively from older to younger groups. Nature-relatedness predicted intentions and identification skills predicted nature-relatedness across all groups. Our findings support the importance of fostering nature-relatedness and species knowledge through age-sensitive access to urban green areas with opportunities to connect with and learn about nature.

This geo-historical case study analyses Vistelius’ ingenious idea of conceptual stochastic models and their application as Markov chain analysis in the geosciences. Vistelius (1915–1995) is regarded as one of the founders of mathematical geology. He was the first to define mathematical geology as “a scientific discipline concerned with the construction, analysis and use of conceptual mathematical models of geological events to solve concrete problems” (Vistelius in Principles of mathematical geology, Nauka, Leningrad, 1980; Principles of mathematical geology, Kluwer Academic Publishers, Dordrecht, 1992). Mathematical models in this context should be primarily probabilistic because of the large number of influencing natural factors. They must be conceptual to avoid fundamental errors in application. Vistelius devoted his seminal book to geological random sequences and their description and analysis using Markov models as stochastic tools. He applied this approach to grain sequences in granitic intrusive rocks and to sedimentary rock layers. Among other things, Vistelius has used Markov chain analysis in mineral resource exploration to distinguish between “ideal” granites, which are not subsequently mineralized, and mainly hydrothermally mineralized, sometimes ore-bearing granites which contain at least two generations of main minerals. The application of this special conceptual stochastic model is demonstrated on Lusatian granite (Saxony, Germany).

Schizophrenia is a chronic and severe mental disorder. It is currently treated with antipsychotic drugs (APD). However, APD’s work only in a limited number of patients and may have cognition impairing side effects. A growing body of evidence points out the potential involvement of abnormal sphingolipid metabolism in the pathophysiology of schizophrenia. Here, an analysis of human gene polymorphisms and brain gene expression in schizophrenia patients identified an association of SMPD1 and SMPD3 genes coding for acid- (ASM) and neutral sphingomyelinase-2 (NSM). In a rat model of psychosis using amphetamine hypersensitization, we found a locally restricted increase of ASM activity in the prefrontal cortex (PFC). Short-term haloperidol (HAL) treatment reversed behavioral symptoms and the ASM activity. A sphingolipidomic analysis confirmed an altered ceramide metabolism in the PFC during psychosis. Targeting enhanced ASM activity in a psychotic-like state with the ASM inhibitor KARI201 reversed psychotic like behavior and associated changes in the sphingolipidome. While effective HAL treatment led to locomotor decline and cognitive impairments, KARI201 did not. An RNA sequencing analysis of the PFC suggested a dysregulation of numerous schizophrenia related genes including Olig1, Fgfr1, Gpr17, Gna12, Abca2, Sox1, Dpm2, and Rab2a in the rat model of psychosis. HAL and KARI201 antipsychotic effects were associated with targeting expression of other schizophrenia associated genes like Col6a3, Slc22a8, and Bmal1, or Nr2f6a, respectively, but none affecting expression of sphingolipid regulating genes. Our data provide new insight into a potentially pathogenic mechanism of schizophrenia and suggest a new pharmaco-treatment strategy with reduced side effects.

The thermal unfolding of lysozyme in aqueous solution has been analyzed by (nano) differential scanning fluorimetry (nanoDSF) and differential scanning calorimetry (DSC). In addition, dynamic light scattering (DLS) acquired in parallel to the DSF measurements, was used to confirm that the change in hydrodynamic radius upon unfolding is rather small (RH,f=1.75 nm in the folded state; and RH,u=1.91 nm in the unfolded state). NanoDSF measurements were evaluated to characterize the folding/unfolding transition within the classical two-state folding model. The temperature of unfolding (Tm) is found to be the most robust quantity. The unfolding enthalpy DHu and the change of specific heat were also obtained and errors in the range of 5–10% and 30–50% were determined, respectively. A comparison of thermodynamic parameters from nanoDSF and DSC measurements provides evidence for an increasing unfolding enthalpy DHu with protein concentration. A comparison with data from literature suggests that a weak association in the folded state can lead to the observed change of the unfolding enthalpy. For Δcp significantly higher values is deduced from the analysis of temperature dependent nanoDSF measurements (10 kJ/(K mol)) as compare to DSC (3–5 kJ/(K mol)).

In this article, we examine the clinical encounters of people diagnosed with a severe mental illness (SMI). Drawing on more than 1-year of ethnographic research and interviews in Indonesia, we show that instances of moral self-reflection occurring in the process of acquiring and appropriating clinical insight emerge at the intersection of heterogeneous discursive regimes. When biomedical notions of health and illness dominate these discourses, they reimagine pre-existing notions about spirituality and religion. Furthermore, consenting to psychiatric notions of health and illness can create common ground and a sense of shared experience, leading to grassroots movements for the empowerment of the mentally ill, self-help groups, and other support structures. At the same time, these processes can increase uncertainty and be generative of a culture of blame, as individuals are caught in overlapping and at times contradictory moral systems that each have the potential to strip patients of their moral status.