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Electronic excitations in hybrid perovskites
No full textMetallhalogenid-Perowskite sind von besonderem Interesse als Lichtabsorber in Solarzellen und zunehmend auch für andere optoelektronische Anwendungen. Ihre theoretische Untersuchung ist anspruchsvoll, da sie eine große strukturelle Vielfalt und entsprechend große Einheitszellen aufweisen können. Zudem enthalten sie oft schwere Elemente, die starke Spin-Bahn-Wechselwirkungen verursachen, deren genaue und effiziente Behandlung eine Herausforderung darstellt. In dieser Arbeit werden elektronische Anregungen in drei- und zweidimensionalen hybriden Bleijodid-Perowskiten mithilfe der Dichtefunktionaltheorie und Methoden der Vielteilchenstörungstheorie untersucht. Ein Schwerpunkt liegt auf der Entwicklung effizienter und genauer Verfahren zur Berechnung der Bandlücken. In diesem Zusammenhang werden verschiedene Austausch-Korrelations-Funktionale und deren Leistungsfähigkeit als Ausgangspunkt für One-Shot-GW-Berechnungen untersucht. Ein besonderer Schwerpunkt liegt auf den Hybridfunktionalen PBE0 und HSE06 sowie auf Methoden zur Bestimmung ihrer Parameter. Zudem wird untersucht, inwieweit organische Bestandteile durch Cäsiumatome ersetzt werden können, um die Größe zweidimensionaler Systeme zu verringern. Nach der Validierung dieses Ansatzes für eine 7-Atom-BA2PbI4-Zelle wird er auf die Hoch- und Tieftemperaturphasen angewendet. Alle Studien wurden mit dem all-electron full-potential exciting-Code durchgeführt, der augmentierte ebene Wellen und lokale Orbitale als Basisfunktionen nutzt. Zur Erzielung der präsentierten Ergebnisse wurden verschiedene Implementierungen realisiert. Besonders die Einführung des HSE06-Funktionals stellt einen wichtigen Fortschritt dar. Die starken Spin-Bahn-Kopplungseffekte erforderten zusätzliche Weiterentwicklungen, darunter eine Methode, die relativistische lokale Orbitale als explizite Basisfunktionen im Second-Variation-Schema verwendet.Metal halide perovskites are of particular interest as light absorbers in solar-cell devices. More recently, interest has extended to many other optoelectronic applications. The study of their electronic excitations using theoretical methods presents many challenges. These include the variety of structures that they can form and the large unit-cell sizes they can easily reach. Moreover, they are made by heavy elements, which causes large spin-orbit coupling effects that are difficult to treat accurately and efficiently. This thesis presents a study of electronic excitations in 3D and two-dimensional (2D) hybrid lead-iodide-based perovskites using density-functional theory and many-body perturbation theory. One focus is the search for efficient and accurate methods to compute their band gaps. In this context, we consider different exchange-correlation functionals and their performance as starting points for one-shot GW calculations. A special focus is on the hybrid functionals PBE0 and HSE06, including methods for tuning their parameters. In addition, we investigate the effect of replacing the organic part with a cesium atom to reduce the size of the 2D systems. After validating this approach for a 7-atom BA2PbI4 cell, the same approach is applied to its high and low-temperature phases. All these studies are performed with the all-electron full-potential code exciting, using augmented plane waves and local orbitals as basis functions. To achieve the results presented, we realize different implementations. Among them, that of HSE06 is a major step forward for the exciting code. The presence of significant spin-orbit coupling effects also required new advancements. In this context, we develop an efficient and accurate method that uses relativistic local orbitals as explicit basis functions in the second variation scheme
Der Chiton im Wandel. Teil V - Multimedia (Abbildungen II)
No full textDiese ZIP-Datei enthält die Abbildungen 84 bis 117a des Abbildungsteils sowie ein Abbildungsverzeichnis mit Bildnachweis. Da einige der bereitgestellten Fotos oftmals unterschiedliche Lizenzen aufweisen, finden sich diese im Abbildungsverzeichnis direkt unter der entsprechenden Abbildungsnummer vermerkt. Sowohl zur jeweiligen Lizenz als auch zur Quelle des Bildes führen entweder Links oder Angaben zu Printmedien.Diese dissertationsbezogenen Forschungsdaten gehören als separat vorliegender Appendix zur Dissertationsarbeit: Der Chiton im Wandel. Er bildet Teil V und umfasst den Multimedia-Bereich. In erster Linie sind hier die durchnummerierten Fotoabbildungen und Videos zusammengestellt, auf die im Text verwiesen wird. Ebenso ist das entsprechende Abbildungsverzeichnis mit den Bildnachweisen in diesem Teil enthalten. Des Weiteren befinden sich hier die eigens erstellten Verzeichnisse, in denen Informationen gesammelt und zusammengestellt sind, die zwar auch Resultate der Forschungsarbeit darstellen, aber nicht unmittelbar Bestandteil der Untersuchung sind. Hierzu gehören das Griechische Glossar und die Tabelle zur Terminologie. Ersteres ist eine begonnene Sammlung an griechischem (Bekleidungs-)Vokabular, das in den herangezogenen Schriftquellen auftaucht. Bei Letzterem handelt es sich um eine Zusammenstellung, die die teils in der Forschungsliteratur verschieden verwendeten Termini für den Chiton mit ihrem jeweiligen Schnittschema, einer Definition und dem entsprechenden Forscher verknüpft.This study-related research data is a separate appendix to the dissertation: Der Chiton im Wandel. It forms Part V and is called the multimedia section. Primarily, it contains the figures and videos and the corresponding list of illustrations with picture credits. Additionally, this section includes self-created indexes – the Greek glossary and the terminology table. These are not part of the PhD thesis but resulted from the research process – using them can make it easier to work with some text references of written sources. The glossary is an initiated (ongoing) collection of Greek (clothing) vocabulary that appears in written sources. The table is a compilation that links the terms for the chiton – some of these are used differently in the research literature – with their respective pattern, a definition, and the corresponding researcher
The case of the German bioeconomy
No full textThe article processing charge was funded by the Open Access Publication Fund of Humboldt-Universität zu Berlin.The transition towards a sustainable bioeconomy still faces several difficulties, which have persisted during the last decades despite the intense efforts to support the bioeconomy by introducing policy measures. This study aims to foster a systematic understanding of factors that hinder the transition towards a sustainable bioeconomy and explores how the policy mix addresses those problems. In particular, we assess how the policy mix reacts to blocking mechanisms that hinder system functioning by studying the bioeconomy in Germany through the lens of the Technological Innovation Systems. In this regard, we analyze the policy mix elements introduced between 2006 and 2024 along three core blocking mechanisms, which we labelled as: Market Uncertainty, Policy Uncertainty, and Feedstock Uncertainty. The results reveal that the policy mix reacts to the identified bottlenecks by adding new or updating existing elements over time. These measures are yet mainly soft policy instruments. The policy mix will benefit from stricter instruments to foster the transition more substantially.Peer Reviewe
Sustainable mechanochemical approach for the selective synthesis of multicomponent organic solids: real-time in situ insights
No full textCrystalline multicomponent organic solids (MOSs) such as cocrystals and ionic cocrystals hold immense potential in diverse functional applications, ranging from pharmaceuticals to optoelectronics. However, conventional solution-based crystallization methods often result in polymorphic mixtures and lack precise control over product composition. Herein, we report a comparative investigation of solution crystallization versus mechanochemical synthesis for constructing MOSs from 9-anthracenecarboxylic acid (ACA) and 4,4′-bipyridine (BPY). Solution-based approaches consistently yielded concomitant formation of neutral cocrystal (CC) and ionic cocrystal (ICC) forms, regardless of the solvent used. The resulting multicomponent solids were comprehensively characterized using a combination of single crystal X-ray diffraction, powder X-ray diffraction, Fourier-transform infrared spectroscopy, differential thermal analysis, and thermogravimetric analysis. In contrast, mechanochemical methods, including neat grinding (without solvent) and liquid-assisted grinding (with minimum solvent), enabled selective formation of either a phase pure CC or ICC form. Less polar and nonpolar organic solvents favor the kinetic CC, while polar water promotes formation of the thermodynamically stable ICC. Time-resolved in situ powder X-ray diffraction (TRIS-PXRD) captures the dynamic evolution of solid-state phases and reveals the complete transformation of the CC into ICC under neat grinding or water-assisted conditions. This study highlights the powerful role of mechanochemistry and in situ monitoring in steering solid-state reactivity and offers a sustainable pathway for the targeted and scalable synthesis of pure multicomponent organic materials.Peer Reviewe
Modernes Personengesellschaftsrecht
No full textThe publication of this work was supported by the Open Access Publication Fund of Humboldt-Universität zu Berlin.Das Personengesellschaftsrecht erfindet sich neu. Mit dem MoPeG vollzieht das Recht der GbR, OHG und KG den größten Wandel seit 1900. Der vorliegende Band beleuchtet in einer umfassenden Bestandsaufnahme die neuen und alten Grundstrukturen des Personengesellschaftsrechts und ihre praktischen Anwendungen. Renommierte Expertinnen und Experten aus Wissenschaft und Praxis analysieren kritisch zentrale Themen wie das neue Gesellschaftsregister, das Beschlussanfechtungsrecht und die Kommanditistenhaftung. Dabei nehmen sie auch die Herausforderungen der Zukunft in den Blick: Von Krypto-, und Daten-Gesellschaften über Venture Capital bis zu grenzüberschreitenden Konstellationen. Der Band verbindet dogmatische und methodische Fundierung mit praxisnaher Perspektive und zeigt bestehende Systemlücken sowie Handlungsbedarf auf. Länderberichte zur Schweiz und zu Österreich runden das Werk ab
Projections of climate change vulnerability along the Shared Socioeconomic Pathways 2020–2100
No full textThis data descriptor presents the GVI Projections Database with projections of socioeconomic vulnerability for the period 2020–2100 along three Shared Socioeconomic Pathways (SSPs) for almost all countries of the world. The projections are based on the GDL Vulnerability Index (GVI), a composite index for monitoring the human components of vulnerability to climate change, natural disasters and other shocks for societies and geographic areas across the globe. The GVI is based on an additive formula that summarizes the essence of seven major socioeconomic dimensions of vulnerability into one number. This formula approach makes it possible to compute the index for any region at any point in time for which the underlying indicators are available. We derive projections of these indicators from the SSP databases for each fifth year in the period 2020–2100. These projections are subsequently used to compute future GVI values for countries and major global regions for three SSPs: the green road scenario (SSP1), the middle of the road scenario (SSP2), and the rocky road scenario (SSP3).The research presented in this paper was conducted for the Climate Vulnerability Monitor 3 (CVM3) project of the Climate Vulnerability Forum (CVF) and funded by the United Nations Office for Project Services (UNOPS) under grant number 22146/2021/05.Peer Reviewe
Centimeter-Sized Single Layer WSe2 by Gold-Mediated Exfoliation for Ambipolar Field Effect Transistors at Ultra-Low Voltages
No full textThe article processing charge was funded by the Open Access Publication Fund of Humboldt-Universität zu Berlin.Transition Metal Dichalcogenides (TMDCs) are promising semiconductor alternatives to silicon in CMOS technology. Their layered nature allows scaling to a single layer (1L) without degrading electrical performance, enabling further miniaturization of field-effect transistors (FETs). TMDCs like WSe2 exhibit ambipolar transport, allowing fabrication of both p-type and n-type devices on a single flake, simplifying circuit design. Ambipolar, large-area, high-quality 1L-WSe2 is therefore highly desirable. Here, centimeter-scale exfoliated 1L-WSe2 is achieved, reaching 1L areas of up to 20 mm2 via thermally activated gold-mediated TMDC exfoliation using large, high-quality WSe₂ parent crystals. The quality of 1L-WSe2 is comprehensively investigated via Raman spectroscopy, photoluminescence, X-ray, and ultraviolet photoelectron spectroscopy, as well as electronic transport measurements. For the latter, 1L-WSe2-based FETs are fabricated on lithium-ion conducting glass ceramic substrates serving as both supporting substrate and high-performance gate. Subthreshold slopes as steep as 30 and 50 mV dec−1, maximum mobilities of 15 and 18 cm2 V⁻¹ s⁻¹, and ON/OFF ratios of ≈108 and 109 for electron and hole currents, respectively, are achieved at ultra-low gate voltages (≈2 V). The performance, demonstrated across 15 devices, suggests that 1L-WSe2 in this device architecture can pave the way toward providing an alternative to conventional silicon-based CMOS technology for innovative, further miniaturized devices.Peer Reviewe
Die Wahrheit der Anderen: Zeugnis, Zweifel und Zauberei in Valvasors Ehre dess Herzogthums Crain
No full textPeer Reviewe
Differential Gaze Disengagement from Friendly and Disdainful Facial Expressions Predicts Reliable Increase of Depressive Symptoms Following Euthymia: Preliminary Evidence from an Eye-Tracking Study at 6-Month Follow-up
No full textBackground: Attentional biases to emotional information are assumed to play a crucial role in the onset and maintenance of depression. Moreover, recent studies show that biases may remain present in previously affected individuals during non-symptomatic stages even after acute depression has fully subsided. For example, in an investigation probing attentional disengagement from facial expressions of happiness, sadness, and disgust, never-depressed individuals showed speeded disengagement from disgusted expressions in comparison to happy faces, but this differential processing pattern was absent in currently euthymic individuals with a history of major depression. Purpose: Building on these findings, the present follow-up study aimed to explore the predictive power of that previously described disengagement bias by assessing depressive symptoms in 63 initially euthymic individuals six months after they had participated in a gaze-contingent eye tracking task. Methods: Each participants’ mean difference in saccade latency to initiate eye movements away from facial expressions of happiness and disgust was assessed at baseline, and tested for associations with self-reported depressive symptom gains six months later. Results: The individual’s difference between these two emotion conditions when performing attentional disengagement (ADΔhappiness-disgust) significantly predicted the occurrence of a reliable increase in depressive symptom severity at six months follow-up. This effect remained significant when controlling for baseline symptom severity and lifetime history of depression. Conversely, dimensional change in depressive symptom severity was not predicted by the ADΔhappiness-disgust score. Conclusions: We suggest that an individual difference score reflecting the ability to disengage attention from facial expressions of disgust versus happiness may be particularly useful in identifying individuals prone to experiencing reliable increases in depressive symptoms.Open Access funding enabled and organized by Projekt DEAL.Robert-Enke-Stiftung, GermanyStudienstiftung des deutschen Volkes, GermanyHumboldt-Universität zu Berlin (1034)Peer Reviewe
BORC-mediated regulation of TLR7 and its implications for lupus
No full textDer Toll-like-Rezeptor 7 (TLR7) ist ein intrazellulärer Mustererkennungsrezeptor, der einzelsträngige RNA (ssRNA) erkennt und eine zentrale Rolle in der antiviralen Immunität spielt. Eine übermäßige TLR7-Aktivierung wird zunehmend mit Autoimmunerkrankungen in Verbindung gebracht. Jüngste Studien haben Mutationen in TLR7 und seinem Chaperon UNC93B1 als monogene Ursachen für systemischen Lupus erythematodes (SLE) identifiziert und damit die Bedeutung einer präzisen Regulation der TLR7-Signalübertragung hervorgehoben. Diese Mutationen führen zu einer hyperaktiven TLR7-Signalgebung und zum Verlust der Immuntoleranz gegenüber körpereigenen Nukleinsäuren. TLR7 befindet sich in späten endosomalen Kompartimenten, die ein dynamisches Transportnetzwerk bilden und zentrale Funktionen für Signalübertragung und Proteinabbau erfüllen. Zusammen mit UNC93B1 durchläuft TLR7 dieses System, um sein Signalkompartiment zu erreichen. Eine genaue Steuerung dieses Transports ist entscheidend, um Fehlaktivierungen zu vermeiden. In dieser Arbeit identifiziere ich den BLOC-1-Related Complex (BORC) als entscheidenden Regulator des TLR7-Abbaus. BORC fördert über seine Effektor-GTPase Arl8b den homöostatischen Abbau von TLR7. Co-Immunpräzipitationen und funktionelle Analysen zeigen eine selektive Interaktion zwischen TLR7 und Arl8b, vermittelt durch UNC93B1, das mit TLR7 assoziiert bleibt, sich aber von anderen endosomalen TLRs wie TLR3 und TLR9 löst. Diese anhaltende Bindung ermöglicht die Rekrutierung des BORC–Arl8b-Komplexes und den gezielten Abbau von TLR7. Eine Störung dieser Interaktion, entweder durch Mutationen in UNC93B1 oder den Verlust von BORC-Komponenten führt zu einer Akkumulation von TLR7 und verstärkter Signalübertragung. Eine de novo UNC93B1-Mutation bei einem Kind mit früh einsetzendem Lupus zeigte eine gestörte Arl8b-Bindung und reduzierten TLR7-Abbau. Dies belegt einen mechanistischen Zusammenhang zwischen gestörtem endosomalem Transport und Autoimmunität. Diese Arbeit beschreibt einen neuartigen Abbauweg, der TLR7-Aktivität gezielt begrenzt, und zeigt, dass der BORC–Arl8b-Komplex als Schutzmechanismus fungiert, der übermäßige Immunreaktionen und den Verlust der Selbsttoleranz verhindert.Toll-like receptor 7 (TLR7) is an intracellular pattern recognition receptor that recognizes single-stranded RNA (ssRNA) and plays a central role in antiviral immunity. However, excessive TLR7 activation has increasingly been linked to autoimmune diseases. Recent studies have identified mutations in TLR7 and its chaperone UNC93B1 as monogenic causes of systemic lupus erythematosus (SLE), underscoring the importance of precise regulation of TLR7 signaling. These mutations lead to hyperactive TLR7 signaling and the loss of immune tolerance to self-nucleic acids. TLR7 resides within late endosomal compartments that form a dynamic trafficking network essential for signal transduction and protein degradation. Together with UNC93B1, TLR7 passes through this system to reach its signaling compartment. Tight regulation of this trafficking is crucial to prevent aberrant receptor activation. In this study, I identify the BLOC-1-related complex (BORC) as a critical regulator of TLR7 degradation. BORC, through its effector GTPase Arl8b, promotes the homeostatic turnover of TLR7. Co-immunoprecipitation and functional analyses reveal a selective interaction between TLR7 and Arl8b, mediated by UNC93B1, which remains associated with TLR7 but dissociates from other endosomal TLRs such as TLR3 and TLR9. This persistent association enables recruitment of the BORC–Arl8b complex and targeted degradation of TLR7. Disruption of this interaction, either through mutations in UNC93B1 or genetic loss of BORC components leads to TLR7 accumulation and enhanced downstream signaling. A de novo UNC93B1 mutation identified in a child with early-onset lupus showed impaired binding to Arl8b and defective TLR7 degradation. This establishes a mechanistic link between disturbed endosomal trafficking and autoimmunity. This work uncovers a novel degradation pathway that selectively constrains TLR7 activity and demonstrates that the BORC–Arl8b complex acts as a safeguard preventing excessive immune activation and the breakdown of self-tolerance