Kiel University

Wet-chemical processing of metals, for example, galvanic deposition, etching, and nanoparticle synthesis, usually requires complexing agents. In particular, for noble metal processing, anionic complexing species, such as halides or sulfide are indispensable. While it is known that these species strongly adsorb on metal surfaces and affect metal nucleation and growth, the detailed role of these anions in the underlying atomistic processes is less clear. Often, it is assumed that surface complexes are involved, but experimental evidence for the latter is still lacking. Here, we present direct in situ video-rate scanning tunneling microscopy observations of gold-bromide and gold-sulfur surface complexes on Au(100) electrodes. Based on the intramolecular resolution images obtained in these studies, these species can be assigned to a dimeric planar and a linear complex. Once formed, the surfaces complexes are stable even at rather negative potentials and diffuse as molecular species on the Ausurface.

Quantification of the human S100A8/S100A9 tetrameric protein complex in stool, referred to as fecal calprotectin, is an extensively validated biomarker supporting the diagnosis and management of gastrointestinal diseases. Here, we studied the quaternary protein structures (termed configuration) of S100A8 and S100A9 and their biological function in inflammatory bowel diseases (IBD). We dissected fecal S100A8 and S100A9 configurations in patients with IBD by size-exclusion chromatography coupled with tandem mass spectrometry and systematically defined human S100A8 and S100A9 homodimer functions compared with the calprotectin heterotetramer (CP) in the intestine of mice and in human epithelium and T cells. Moreover, we report a protein interaction network of fecal S100A8 and S100A9 in IBD. Stool from patients with active IBD contained abundant S100A8 and S100A9 dimers besides CP. Fecal S100A9 detection associated with clinical and endoscopic disease activity in IBD patients with low CP concentration. Oral exposure to human recombinant S100A8 and S100A9 homodimers, but not to CP, worsened intestinal inflammation in toxic and genetic mouse models. Functional profiling revealed that human S100A8 and S100A9 homodimers enhanced activation of cluster of differentiation 4+ and 8+ T cells, which promoted experimental colitis. In turn, genetic inactivation of S100a9 protected against experimental enteritis and colitis, and pharmacologic inhibition of S100A9 ameliorated chronic colitis. Collectively, this study links the detection of fecal S100A9 dimers with clinical and endoscopic disease activity in IBD and identifies inflammatory actions of S100A8 and S100A9 homodimers in the intestine. Our findings pave the way for novel diagnostic and therapeutic approaches in patients with inflammatory diseases of the intestine.

Abstract The Late Antique Migration period (LAMP; 300–700 CE) in what is today northeastern Germany was marked by significant socio-environmental shifts, including a decline in human activity, the abandonment of settlements, and a reduction in cereal cultivation, particularly of rye ( Secale cereale ). While these changes are well documented in pollen and archaeological records, the underlying drivers—whether socio-political instability, agricultural crises, or environmental pressures—remain debated.
Here, we use a multiproxy approach comprising high-resolution pollen data, archaeobotanical data, and climate reconstructions specific to the study area to explore the interplay between climatic fluctuations, agricultural practices, and human mobility during the LAMP. Although previous studies have examined socio-environmental changes during the Migration period using archaeological and palynological evidence, this study is the first to integrate these three proxies to systematically evaluate the role of climatic anomalies in shaping agricultural and demographic patterns.
We focus on the Dark Age Cold Period (DACP; 350–700 CE) and the Late Antique Little Ice Age (LALIA; 536–660 CE), which brought cold and wet conditions to northern Europe, likely disrupting agricultural productivity and fostering the spread of Claviceps purpurea (ergot), a fungus toxic to humans affecting cereal crops, particularly rye. Our findings suggest that these two climatic anomalies created favorable conditions for outbreaks of ergot, leading to agricultural instability and reduced food security, which, combined with socio-political pressures, contributed to the observed decline in human activity and settlement abandonment.
We suggest that climatic anomalies in the DACP and LALIA, coupled with the vulnerability of cereal crops to ergot infestation, influenced agricultural and demographic shifts in northeastern Germany. This paper not only refines our understanding of the DACP and the LALIA, but also demonstrates how climatic stressors and natural hazards can amplify socio-political vulnerabilities in pre-industrial societies.

ABSTRACT We benchmark nonequilibrium Green's function (NEGF) approaches for interaction quenches in the half‐filled Fermi–Hubbard model in one and two dimensions. We compare fully self‐consistent two‐time Kadanoff–Baym equations (KBE), the generalized Kadanoff–Baym ansatz (GKBA), and the recently developed NEGF‐based quantum fluctuations approach (NEGF‐QF) with second‐order Born (2B) and GW self‐energies. As references, we use DMRG in 1D and time‐dependent perturbation theory at weak coupling. While all methods reproduce the early‐time build‐up of correlations (prethermalization), different deficiencies emerge during the slower relaxation in the long‐time limit: KBE shows overdamped oscillations, GKBA exhibits a negative overshoot of the Fermi‐surface jump, and NEGF‐QF develops a prethermalization plateau with delayed relaxation. In 1D, we find that GKBA + 2B agrees best with DMRG across the explored parameter range, while QF + GW deviates the most, consistent with its reduced self‐consistency. In 2D, all approaches correctly capture the momentum‐dependence of the relaxation dynamics.

Emerging fungal pathogens have detrimental impacts on crops, animals, and humans. Despite the mounting threat of these emerging fungal pathogens, little is known about their transition from saprotrophic to pathogenic lifestyles. To gain insights into fungal lifestyle transitions, we study the Trichosporonales order, which includes both saprotrophic species and opportunistic human pathogens, as a system to reveal evolutionary adaptations leading to virulence in fungi. Here we use comparative genome analyses and experimental assays to demonstrate that the transition from saprotroph to opportunistic human pathogen is facilitated by adaptive translation. Codon optimization of metabolic genes grants these fungi the ability to quickly adapt to new environments. In this study, we link genomic data with fungal physiology, highlighting the role of adaptive translation in colonizing different environments and suggesting that gene translation optimization plays a critical role in fungal lifestyle evolution.

Conventional T cells recognize peptides presented by the human leukocyte antigen (HLA) proteins through their T cell receptors (TCRs). Given that thousands of HLA proteins have been discovered, each presenting thousands of different peptides, decoding the cognate HLA protein of a TCR experimentally is a challenging task. To address this problem, we combined statistical learning methods with a unique dataset of paired T cell repertoires and HLA allotypes for 6,794 individuals. This enabled us to discover 34,206 T cell receptor alpha (TRA) and 891,564 beta (TRB) clonotypes that were associated with 175 unique HLA alleles. The identified clonotypes target prevalent infections, e.g. influenza, cytomegalovirus and Epstein-Barr virus. Utilizing these clonotypes, we develop statistical models that impute the carriership of common HLA alleles from the TRA- or the TRB- repertoire. In conclusion, the identified allele-associated clonotypes encode the HLA fingerprints and the antigenic exposure history of individuals and populations.