31325 research outputs found
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Topological classification of cycloadditions occurring on-surface and in the solid-state
No full textThe study of cycloaddition mechanisms is central to the fabrication of extended sp 2 carbon nanostructures such as graphene nanoribbons and spin chains. Reaction modeling in this context has focused mostly on putative, energetically preferred, exothermic products with limited consideration for symmetry allowed or forbidden mechanistic effects. To classify and optimize allowed reaction mechanisms, modern topological tools can be explored. Here, we introduce a scheme for classifying symmetry-forbidden reaction coordinates in Woodward-Hoffmann correlation diagrams. We show that topological classifiers grant access to the study of reaction pathways and correlation diagrams in the same footing, for the purpose of elucidating mechanisms and products of polycyclic aromatic azomethine ylide (PAMY) cycloadditions of pentacene-yielding polycyclic aromatic hydrocarbons with an isoindole core in the solid-state and on surfaces, as characterized by mass spectrometry and scanning tunneling microscopy, respectively. By means of a tight-binding reaction model and broken-symmetry density functional theory (DFT), we find topologically-allowed pathways for an endothermic reaction mechanism. Our work unveils topological classification as a crucial element of reaction modeling for nanographene engineering, and highlights its fundamental role in the design of cycloadditions in on-surface and solid-state chemical reactions, while underscoring that exothermic pathways can be topologically-forbidden.National Natural Science Foundation of China (National Science Foundation of China)https://doi.org/10.13039/501100001809The German Research Foundation (DFG) within the Clusters of Excellence “Center for FiAdvancing Electronics Dresden (cfaed)”, “Matters of Activity”, the DFG-SNSF Research Project (EnhanceTopo, No. 429265950), the K. C. Wong Education Foundation of Chinese Academy of Sciences, the National Key Research and Development Program of China (Grant No. 2020YFA0308800) and the Alexander von Humboldt Foundation.Peer Reviewe
Working memory load-dependent modulation of neural activity predicts response to cognitive behavioral therapy in obsessive-compulsive disorder
No full textCognitive behavioral therapy (CBT) is an effective treatment for obsessive-compulsive disorder (OCD). However, CBT does not lead to a satisfying symptom reduction in a considerable number of patients with OCD. The identification of variables that predict insufficient treatment response could improve efficient treatment selection and inform the development of specific augmentative treatments. In the current study, we tested whether prediction of treatment response can be improved by including neurobiological markers during working memory (WM) performance. Forty-four patients with a primary OCD diagnosis participated in an n-back WM task with varying WM load while functional Magnetic Resonance Imaging (fMRI) was performed. Subsequently, all patients received CBT in an outpatient clinic. WM load-dependent modulation of the blood-oxygen-level-dependent (BOLD) signal in a bilateral cluster in inferior/superior parietal lobule predicted CBT response over and above clinical and sociodemographic variables (p < 0.05). Higher modulation was associated with larger relative symptom reduction. The results of the current study indicate that the ability of the WM system to flexibly adapt to changing task demands might be a useful indicator of CBT response in OCD. Possibly, this mechanism facilitates relearning processes during exposure-based CBT. However, findings need to be replicated in larger samples.Deutsche Forschungsgemeinschaft (German Research Foundation)https://doi.org/10.13039/501100001659Peer Reviewe
Monostudiengang, Überfachlicher Wahlpflichtbereich für andere Bachelorstudiengänge und -studienfächer
No full textQuantifying age-related disparities in outpatient psychotherapy utilization: a representation quotient analysis of routine data from 29 university clinics in Germany
No full textBackground: Although mental disorders are highly prevalent among older adults, evidence suggests that they underutilize psychotherapy. However, formal estimates of their actual representation in routine clinical settings are scarce. This study applied a representation quotient approach to identify and quantify age-related disparities in outpatient psychotherapy utilization in Germany. Methods: We analyzed data from 13,635 adult patients who initiated cognitive-behavioral therapy between 2018 and 2023 at 29 university outpatient clinics. Using a representation quotient approach, we compared the observed proportions of young-old adults (65–74 years) and old-old adults (≥75 years) with prevalence-stratified population age distributions. The robustness of the results was investigated by extensive sensitivity analyses, including alternative prevalence assumptions and adjustments for long-term care needs. Results: Even under conservative assumptions, young-old adults only accounted for about 25% and old-old adults for about 13% of their expected proportion. In contrast, young working-age adults (18–34 years) were particularly overrepresented in the sample. Underrepresentation of older adults was most pronounced among patients with post-traumatic stress disorder, eating disorders, and dysthymia, less pronounced among patients with generalized anxiety disorder, and not significant among patients with pain disorders. Conclusion: This study demonstrates the utility of representation quotients for systematically identifying and quantifying age-related disparities in psychotherapy utilization based on routine care data. Our analyses of large-scale data from university outpatient clinics in Germany revealed a marked underrepresentation of older adults in this setting. These findings highlight the need to improve access to, and utilization of, psychotherapeutic services for older adults.Open Access funding enabled and organized by Projekt DEAL.Friedrich-Schiller-Universität Jena (1010)Peer Reviewe
Kern- und Zweitfach im Kombinationsstudiengang, Überfachlicher Wahlpflichtbereich für andere Bachelorstudiengänge und -studienfächer
No full textTemporal recalibration to delayed visual consequences of saccades
No full textThe article processing charge was funded by the Open Access Publication Fund of Humboldt-Universität zu Berlin.The accurate inference of causality between actions and their sensory outcomes requires determining their temporal relationship correctly despite variable delays within and across sensory modalities. Temporal recalibration—the perceptual realignment of actions with delayed sensory feedback—has been demonstrated across various sensorimotor domains. Here, we investigate whether this mechanism extends to saccadic eye movements and sensory events contingent on them. In three experiments, participants made horizontal saccades that triggered high-contrast flashes at varying delays. They then reported whether the flashes occurred during or after the saccade, allowing us to track perceived event timing. Exposure to consistent delays between saccade onset and the flash led to a shift in perceptual reports: flashes presented after saccade offset were more often judged as occurring during the movement. This recalibration effect was robust even when we manipulated relevant visual cues such as the presence of a structured background or the continuity of the saccade target. In a replay condition, we found a significant but much smaller recalibration effect between replayed saccades and flash, demonstrating the importance of action execution for visuomotor temporal recalibration. These findings highlight the visual system's remarkable adaptability to temporal delays between eye movements and their sensory consequences. A similar recalibration mechanism may support perceptual stability in natural vision by dynamically realigning saccades with their resulting visual input, even amid changing visual conditions.Peer Reviewe
Graphene-Based in situ Electrochemical Plasmon Waveguide Resonance Sensor Incorporating a Polymer Layer
No full textThe article processing charge was funded by the Open Access Publication Fund of Humboldt-Universität zu Berlin.Surface plasmon resonance (SPR) sensing is a suitable analytical technique to obtain kinetic information about the solid–liquid interface. In the standard SPR configuration, a metallic structure is needed, and the sensitivity is limited to the region close to the metal surface. Hence, it is difficult to study electrochemical reactions free of the metal film. Here, the use of a polymer layer on the metal is proposed, which serves as a dielectric waveguide presenting additional modes due to plasmon waveguide resonance (PWR). This helps one to offset the analytical interface a few 100 nm away from the metal surface. For studying electrochemical reactions, a graphene sheet is incorporated as an electrode on top of the polymer waveguide, thereby completely decoupling the electrode from the plasmonic gold layer. As a proof-of-principle, the possibility of following the kinetics of nanoparticle growth and dissolution is demonstrated. Moreover, it is shown that the electrochemical PWR can be used to monitor the redox behavior of immobilized nanoparticles in situ during potential cycling. Although the chemical structural information is not obtained, the ability to extract in situ kinetic data will help us gather a deeper mechanistic understanding of active metal centers in the context of electrocatalysis.Peer Reviewe
A Radical-Cationic Covalent Organic Framework to Accelerate Polysulfide Conversion for Long-Durable Lithium–Sulfur Batteries
No full textCovalent organic frameworks (COFs) have emerged as promising metal-free sulfur hosts to facilitate the conversion kinetics and suppress the shuttling effect of lithium polysulfides (LiPSs) in lithium–sulfur (Li–S) batteries. However, constructing COFs with stable and high electrocatalytic functionality for LiPS conversion remains unexplored. Herein, we develop a radical-cationic COF (R-TTF•+-COF) with superior electrical conductivity of 3.9 S m–1 at room temperature, which features both nucleophilic and electrophilic sites for effective LiPS chemisorption and conversion. With this novel radical-based catalyst, the Li–S battery achieves superior longevity of 1500 cycles with a capacity fading of 0.027% per cycle at a current density of 0.5 C. The capacity retention of the Li–S battery based on R-TTF•+-COF at the current density of 2.0 C is nearly twice as high compared to a COF without radicals. The crucial role of radical cations in catalyzing LiPS conversion has been systematically elucidated through solid-state nuclear magnetic resonance spectroscopy, electron paramagnetic resonance spectroscopy, and theoretical simulations, which verify the reversible interactions between LiPSs and [TTF]2•+ moieties. This intriguing radical-assisted mechanism opens a new avenue for designing efficient catalytic sulfur hosts using organic molecules, offering a significant step toward the practical application of Li–S batteries.Alexander von Humboldt-Stiftung 10.13039/100005156Deutsche Forschungsgemeinschaft 10.13039/501100001659Deutsche Forschungsgemeinschaft 10.13039/501100001659Deutsche Forschungsgemeinschaft 10.13039/501100001659Deutsche Forschungsgemeinschaft 10.13039/501100001659Deutsche Forschungsgemeinschaft 10.13039/501100001659Deutsche Forschungsgemeinschaft 10.13039/501100001659China Scholarship Council 10.13039/501100004543Peer Reviewe
Kompendium artop-Science Day: „Beratungsforschung im Dialog – Systemische Beratung als Forschungsfeld“
No full textDer Science Day am 24. Februar 2025 stand unter dem Thema „Beratungsforschung im Dialog – Systemische Beratung als Forschungsfeld“. Die Veranstaltung, organisiert von Dr. Beate Fietze und Johannes Loermann im Rahmen von artop – Institut an der Humboldt-Universität zu Berlin, versammelte Wissenschaftler:innen, Studierende und Netzwerkpartner:innen, um wissenschaftlich fundierte Perspektiven auf systemische Beratung zu diskutieren.
Ziel war es, aktuelle Forschungsergebnisse zu präsentieren, neue Perspektiven zu entwickeln und den Austausch zwischen Wissenschaft und Praxis zu fördern. Das vorliegende Kompendium enthält die Zusammenfassungen der Vorträge und Diskussionsrunden und gibt einen Einblick in die inhaltlichen Schwerpunkte des Science Days. Jeder Beitrag wird durch eine thematische Einordnung ergänzt, die den Kontext der vorgestellten Inhalte erläutert. Ergänzend werden zu jeder Thematik drei zentrale Literaturempfehlungen gegeben.
Das Kompendium bietet somit sowohl eine inhaltliche Dokumentation als auch eine fundierte Weiterführung der Diskussionen in Theorie und Praxis systemischer Beratung
Enhanced joint energy transfer potential by the biarticular gastrocnemii muscles during perturbed walking
No full textOur objective was to explore how the potential for energy transfer between the ankle and knee joint via the biarticular gastrocnemii muscles is modulated during unpredictable and adapted trip-like and drop-like gait perturbations. Using kinematic parameters of the ankle and knee joints, the energy transfer potential between the two joints was determined as the fraction of contact time when the ankle and knee joint angles are in-phase. Additionally, the electromyographic activity of the gastrocnemius medialis and lateralis were captured during the drop-like perturbations. The energy transfer potential increased 1.6-fold in the trip-like and 2.5-fold in the drop-like perturbations compared to unperturbed walking, indicating a relevant involvement of biarticular mechanisms in maintaining body stability. The activation of the gastrocnemii was high (50–60% of a maximum voluntary contraction) in the phases of ankle-to-knee and knee-to-ankle joint energy transfer, which suggests a relevant contribution of biarticular mechanisms to the management of the body’s energy during the drop-like perturbations. Considering the similar ankle-to-knee joint energy transfer potential compared to unperturbed walking, the higher activation of the gastrocnemii muscles in the first 20% of the stance indicates a greater contribution of biarticular mechanisms to the absorption of body energy in the unpredictable perturbations.Open Access funding enabled and organized by Projekt DEAL.Humboldt-Universität zu Berlin (1034)Peer Reviewe