Imprints of management history on hemiboreal forest ecosystems in the Baltic States

In the Baltic States region, anthropogenic disturbances at different temporal and spatial scales mostly determine dynamics and development phases of forest ecosystems. We reviewed the state and condition of hemiboreal forests of the Baltic States region and analyzed species composition of recently established and permanent forest (PF). Agricultural deforestation and spontaneous or artificial conversion back to forest is a scenario leading to ecosystems designated as recent forest (RF, age up to two hundred years). Permanent forest (PF) was defined as areas with no records of agricultural activity during the last 200 yr, including mostly forests managed by traditional even-aged (clear-cut) silviculture and salvage after natural disturbances. We hypothesized that RF would have distinctive composition, with higher dominance by hardwoods (e.g., aspen and birch), compared to PF. Ordination revealed divergence in the RF stands; about half had the hypothesized composition distinct from PF, with a tight cluster of stands in the part of the ordination space with high hardwood dominance, while the remaining RF stands were scattered throughout the ordination space occupied by PF with highly variable species composition. Planting of conifers, variability in site quality, and variability in spatial proximity to PF with relatively natural ecosystem legacies likely explained the variable compositions of this latter group of RF. We positioned the observations of RF in a classic quantification of site type conditions (based on Estonian forest vegetation survey previously carried out by LA mu hmus), which indicated that RF was more likely to occur on areas of higher soil fertility (in ordination space). Climatic and anthropogenic changes to RF create complex dynamic trends that are difficult to project into the future. Further research in tracing land use changes (using pollen analysis and documented evidence) should be utilized to refine the conceptual framework of ecosystem legacy and memory. Occurrence and frequency of deforestation and its characteristics as a novel disturbance regime are of particular interest.Peer reviewe

Advancing Digital Twin-Based Collision Avoidance: A Comprehensive Analysis of Communication Networks for Safety-Critical Applications in Industry 4.0

This study presents a theoretical framework for defining the performance level of wireless safety functions within industrial environments. While acknowledging the simplifications inherent in our approach—primarily based on packet loss rates as a measure of system performance—the study underscores the dynamic challenges posed by real-world warehouses. Through an in situ measurement study of a forklift truck safety system, we validate the proposed method and emphasize the need for a more nuanced examination of wireless communication in complex settings. The study advocates for an expanded theoretical framework that considers fluctuations in warehouse dynamics, accounting for their impact on packet loss rates and, consequently, the precision of performance-level assessments. Furthermore, the research highlights the complexity introduced by wireless system characteristics not addressed in the simplified model, urging future investigations to incorporate these factors for a comprehensive understanding of wireless safety systems. The absence of specific criteria for wireless systems within existing standards emphasizes the necessity for a specialized framework in addressing safety aspects unique to wireless applications

Effects of electron beam generated lattice defects on the periodic lattice distortion structure in 1T-Ta S2 and 1T-TaS e2 thin layers

We have investigated the influence of electron beam generated defects on the structure of periodic lattice distortions (PLDs) which accompany charge density wave modulations in 1T-TaS2 and 1T-TaSe2. Lattice defects were generated through irradiation with high-energy electrons in a transmission electron microscope (TEM). Using atomically resolved high-resolution TEM imaging, we investigate the PLD structure and the changes in this structure with prolonged exposure to the electron beam. We observe the formation of dislocationlike topological defects in the PLD structure. Prolonged exposure to the electron beam also leads to an increase in density of these defects. This is also accompanied by an increase in structural disorder of the PLD. Density functional theory calculations were also performed in order to understand sulfur (S) and selenium (Se) vacancy defect formation in 1T-TaSe2 and 1T-TaS2 and their effects on the PLD structure. The formation energy of Se/S vacancies was calculated to be lowest for the highly displaced S/Se atoms in the vicinity of PLD maxima. Vacancies formed at the less displaced sites near the PLD minima were found to have lower formation energy. The calculations also showed that an increase in the S/Se vacancies leads to the formation of dislocations and an increase in disorder in the PLD structures. This supports the experimental observations.Peer reviewe

Structural and Chemical Modifications of Few-Layer Transition Metal Phosphorous Trisulfides by Electron Irradiation

Funding Information: We want to thank all cooperation associates in the framework of this manuscript. Further, we especially thank the Institute Laue-Langevin, for the syntheses of the TMPT materials used in this work. We thank Gabriele Es-Samlaoui for successfully preparing the samples for TEM investigation. Further, we thank Hannu Pekka-Komsa for the fruitful discussions on Debye temperatures in TMPTs. This work is supported by a project funded by Carl Zeiss foundation. The computational support from the Technical University of Dresden computing cluster (TAURUS) and High-Performance Computing Center (HLRS) in Stuttgart is gratefully appreciated. We further thank the German Research Foundation (DFG) through projects KR 4866/8-1, the collaborative research center “Chemistry of Synthetic 2D Materials” CRC-1415-417590517, and the collaborative research center “Exploiting the Human Peptidome for Novel Antimicrobial and Anticancer Agents” CRC-1279-316249678 for financial support. Publisher Copyright: © 2022 The Authors. Published by American Chemical Society.Transition metal phosphorous trisulfides (TMPTs) are inorganic materials with inherent magnetic properties. Due to their layered structure, they can be exfoliated into ultra-thin sheets, which show properties different from their bulk counterparts. Herein, we present a detailed analysis of the interaction of the electron beam (30-80 kV) in a transmission electron microscope with freestanding few-layer TMPTs, with the aim of tailoring their properties. The irradiation-induced structure modifications were systematically investigated by various transmission electron microscopy methods on FePS3, MnPS3, and NiPS3, and the results are rationalized with the help of ab initio calculations, which predict that the knock-on threshold for removing sulfur is significantly lower than that for phosphorus. Therefore, a targeted removal of sulfur is feasible. Eventually, our experiments confirm the dose-dependent, predominant removal of sulfur by the impinging electrons, thus showing the possibility of tuning the sulfur concentration. Using ab initio calculations, we analyze the electronic structure of the TMPTs with single vacancies and oxygen impurities and predict distinct electronic properties depending on the type of defect. Therefore, our study shows the possibility of tuning the properties of ultra-thin freestanding TMPTs by controlling their stoichiometry.Peer reviewe

Defect Agglomeration and Electron-Beam-Induced Local-Phase Transformations in Single-Layer MoTe2

Funding Information: We acknowledge funding from the German Research Foundation (DFG), project KR 48661/1, and through the collaborative research center “Chemistry of Synthetic 2D Materials” SFB-1415-417590517. We acknowledge the German Research Foundation (DFG) and the Ministry of Science, Research and the Arts (MWK) of the federal state of Baden-Württemberg, Germany, in the frame of the SALVE (sub-Angström low-voltage electron microscopy) project (KA1295/21-1). We further thank HLRS, Stuttgart, Germany, and TU Dresden (Taurus cluster) for the generous grant of CPU time. Publisher Copyright: ©Atom migrations in single-layer 1H-MoTe2 are studied with Cc/Cs-corrected high-resolution transmission electron microscopy at an electron energy of 40 keV using the electron beam simultaneously for material modification and imaging. After creating tellurium vacancies and vacancy lines, we observe their migration pathways across the lattice. Furthermore, we analyze phase transformations from the 1H- to the 1T′-phase associated with the strain induced due to the formation of Te vacancy lines. Combining the experimental data with the results of first-principles calculations, we explain the energetics and driving forces of point- and line-defect migrations and the phase transformations due to an interplay of electron-beam-induced energy input, atom ejection, and strain spread. Our results enhance the understanding of defect dynamics in 2D transition metal dichalcogenides, which should facilitate tailoring their local optical and electronic properties.Peer reviewe

Electron-Beam- and Thermal-Annealing-Induced Structural Transformations in Few-Layer MnPS3

Funding Information: We want to thank all cooperation associates in the framework of this manuscript. Further, we especially thank the Institut Laue-Langevin for the synthesis of the TMPT materials and Gabriele Es-Samlaoui for the preparation of TEM samples used in this work. This work was supported by the German Science Foundation (DFG), project CRC 1279 (project number 316249678), projects KR 4866/8-1, and the collaborative research center “Chemistry of Synthetic 2D Materials” SFB-1415-417590517. This work was supported by a project funded by the Carl Zeiss foundation. The computational support from the Technical University of Dresden computing cluster (TAURUS) and High-Performance Computing Center (HLRS) in Stuttgart is gratefully appreciated. M.K.K. acknowledges funding from the Deutsche Forschungsgemeinschaft (DFG) within the project DFG: KI 2546/1-1. Publisher Copyright: © 2023 The Authors. Published by American Chemical Society.Quasi-two-dimensional (2D) manganese phosphorus trisulfide, MnPS3, which exhibits antiferromagnetic ordering, is a particularly interesting material in the context of magnetism in a system with reduced dimensionality and its potential technological applications. Here, we present an experimental and theoretical study on modifying the properties of freestanding MnPS3 by local structural transformations via electron irradiation in a transmission electron microscope and by thermal annealing under vacuum. In both cases we find that MnS1-xPx phases (0 ≤ x < 1) form in a crystal structure different from that of the host material, namely that of the α- or γ-MnS type. These phase transformations can both be locally controlled by the size of the electron beam as well as by the total applied electron dose and simultaneously imaged at the atomic scale. For the MnS structures generated in this process, our ab initio calculations indicate that their electronic and magnetic properties strongly depend on both in-plane crystallite orientation and thickness. Moreover, the electronic properties of the MnS phases can be further tuned by alloying with phosphorus.Peer reviewe

Defect agglomeration and electron-beam-induced local-phase transformations in single-layer MoTe2

Abstract Atom migrations in single-layer 1H-MoTe2 are studied with Cc/Cs-corrected high-resolution transmission electron microscopy at an electron energy of 40 keV using the electron beam simultaneously for material modification and imaging. After creating tellurium vacancies and vacancy lines, we observe their migration pathways across the lattice. Furthermore, we analyze phase transformations from the 1H- to the 1T’-phase associated with the strain induced due to the formation of Te vacancy lines. Combining the experimental data with the results of first-principles calculations, we explain the energetics and driving forces of point- and line-defect migrations and the phase transformations due to an interplay of electron-beam-induced energy input, atom ejection, and strain spread. Our results enhance the understanding of defect dynamics in 2D transition metal dichalcogenides, which should facilitate tailoring their local optical and electronic properties

Sonication-assisted liquid exfoliation and size-dependent properties of magnetic two-dimensional α-RuCl₃

Gefördert im Rahmen des Projekts DEA

Hemiboreal forest: natural disturbances and the importance of ecosystem legacies to management

The condition of forest ecosystems depends on the temporal and spatial pattern of management interventions and natural disturbances. Remnants of previous conditions persisting after disturbances, or ecosystem legacies, collectively comprise ecosystem memory. Ecosystem memory in turn contributes to resilience and possibilities of ecosystem reorganization following further disturbance. Understanding the role of disturbance and legacies is a prerequisite for maintaining resilience in the face of global change. Several legacy concepts discussed in the peer-reviewed literature, including disturbance, biological, soil, land-use, and silvicultural legacies, overlap in complex ways. Here, we review these established legacy concepts and propose that the new terms “material legacy” (individuals or matter, e.g., survivors, coarse woody debris, nutrients left after disturbance) and “information legacy” (adaptations to historical disturbance regimes) cut across these previous concepts and lead to a new classification of legacies. This includes six categories: material legacies with above- and belowground, and biotic and abiotic categories, and information legacies with above- and belowground categories. These six legacies are influenced by differential patterns of editing and conditioning by “legacy syndromes” that result from natural or human-manipulated disturbance regimes that can be arranged along a gradient of naturalness. This scheme is applied to a case study of hemiboreal forests in the Baltic States of Estonia, Latvia, and Lithuania, where natural disturbance, traditional clearcut silviculture, and afforestation of abandoned agricultural lands constitute the three main legacy syndromes. These legacy syndromes in turn influence forest response to management actions and constrain resilience, leading to a mosaic of natural, manipulated, and artificial (novel) ecosystems across the landscapeVytauto Didžiojo universitetasŽemės ūkio akademij