31325 research outputs found
Sort by
Rh-doped, InGaAs-based Quantum-Photoconductor with Superior Carrier Mobility-Lifetime Trade-off for THz Time-Domain Spectroscopy
No full textPhotoconductive antennas (PCAs) are key elements for the implementation of fiber-coupled terahertz (THz) time-domain spectroscopy (TDS) systems as they provide high infrared-to-THz conversion efficiency. However, their performance is fundamentally limited by the trade-off between carrier mobility and lifetime that is inherent to the photoconducitve material. Here, we present for the first time Rh-doped InGaAs-based quantum photoconductors (QPCs), which overcome this limitation by spatially seperating carrier transport and trapping. With this approach, a sub-picosecond carrier lifetime of 0.75 ps is achieved in combination with very high carrier mobility of 3397 cm 2 /Vs, which represents a 1.7 times increase compared to state-of-the-art Rh-doped bulk InGaAs PCAs. In addition, we demonstrate the application of these Rh-doped QPCs as photoconductive receivers in a fiber-coupled THz TDS system, achieving a THz spectral bandwidth of more than 6 THz and a peak dynamic range of up to 100 dB. These results are already competitive with the performance of state-of-the-art devices and show the great potential of QPCs for the next generation of fiber-coupled THz TDS systems.Open Access funding enabled and organized by Projekt DEAL.Deutsche Forschungsgemeinschafthttps://doi.org/10.13039/501100001659Fraunhofer-Institut für Nachrichtentechnik, Heinrich-Hertz-Institut HHI (1050)Peer Reviewe
Edit this!: LIBREAS ist 20 und schreibt sich in die Wikipedia. Ein fröhlich-reflexiver Bericht
No full textPeer Reviewe
Lewis-acid induced mechanochemical degradation of polyvinylidene fluoride: transformation into valuable products
No full textPolyvinylidene fluoride (–[CH2CF2]n–, PVDF) waste poses significant environmental challenges due to its recalcitrant nature and widespread use. This study addresses the end-of-life management of PVDF by introducing a novel, sustainable mechanochemical approach for its valorisation. We investigated the degradation of PVDF into value-added materials using ball milling with anhydrous AlCl3 to achieve a quantitative mineralisation producing AlF3 and halide-functionalised graphite, along with gaseous products (HCl and CH4). Mechanistic key steps involve Lewis-acid catalysed C–F bond activation, dehydrofluorination and aromatisation. This approach provides an effective solution for PVDF waste management while offering a promising route for the production of high-value materials from polymer waste streams. Our findings contribute to sustainable practices in polymer recycling and resource recovery, respond to pressing environmental concerns associated with fluoropolymer disposal, and demonstrate the potential to convert polymer wastes into useful products.Deutsche Forschungsgemeinschaft 10.13039/501100001659Peer Reviewe
Broadband high-performance terahertz polarizers by nanoimprint lithography for advanced applications
No full textThe article processing charge was funded by the Open Access Publication Fund of Humboldt-Universität zu Berlin.Terahertz polarizers are needed for advanced spectroscopic systems, but they have drawbacks such as low transmission, short bandwidths, and low extinction ratios. A method for the development of ultrabroadband THz polarizers based on the nanoimprint lithography technique is reported here, in which high performance is achieved for a double-wire-grid polarizer (DWGP) structures on cyclic olefin copolymer (COC) substrates. Over the 0.1–25 THz frequency range, the polymer DWGPs exhibited more than twice the TM-polarized transmittance of their silicon-based counterparts. The degree of polarization was greater than 98% in the 0.1–16 THz range, and the extinction ratio was greater than 65.4 dB at 4.2 THz. THz time-domain spectroscopy (THz-TDS) and Fourier-transform infrared spectroscopy (FTIR) were also employed to characterize the optical properties of materials over the frequency ranges of 0.1–40 THz and 0.9–20 THz, respectively. The nanofabricated polymer DWGP showed better optical properties than the Si DWGP in terms of enhanced TM transmittance and reduced TE leakage. In addition, the prepared COC polarizers exhibited cost-effectiveness, scalability, and durability and can be considered environmentally friendly alternatives to conventional Si-based polarizers. This study opens up the possibility of using polymer-based DWGPs as important high-performance components in THz imaging and sensing applications and in wireless communication systems.Peer Reviewe
DINI-Zertifikat für Open-Access-Publikationsdienste 2025
No full textDas DINI-Zertifikat wurde von der DINI-Arbeitsgemeinschaft Elektronisches Publizieren (https://dini.de/ag/e-pub/) entwickelt, die die erste Version im Jahr 2004 vorlegte. Der Kriterienkatalog des Zertifikats wird von in der AG vertretenen Expert*innen seitdem alle drei Jahre an aktuelle Entwicklungen und Anforderungen angepasst und in andere Sprachen übersetzt. Beim aktuellen Zertifikat handelt es sich um die nunmehr achte Version. Mit dem vorliegenden Kriterienkatalog werden sie in konkrete Mindestanforderungen übersetzt, die an Open-Access-Publikationsdienste zu stellen sind. Diese bilden als Plattformen für die Veröffentlichung und Bereitstellung wissenschaftlicher Publikationen in elektronischer Form wichtige Knotenpunkte für den wissenschaftlichen Kommunikationsprozess und tragen als Open-Access-Dienste zur Verbreitung und Demokratisierung von Wissen bei
Epigenetic markers of disease risk and psychotherapy response in anxiety disorders – a longitudinal analysis of the DNA methylome
No full textEpigenetic mechanisms such as DNA methylation are hypothesized to play a pivotal role in the pathogenesis of anxiety disorders and to predict as well as relate to treatment response. An epigenome-wide association study (EWAS) (Illumina MethylationEPIC BeadChip) was performed at baseline (BL), post-treatment (POST) and 6-month follow-up (FU) in the so far largest longitudinal sample of patients with anxiety disorders ( N = 415) treated with exposure-based cognitive behavioral therapy (CBT), and in 315 healthy controls. Independent of comorbidity with depression, anxiety disorders were significantly ( p ≤ 6.409E–08) associated with altered DNA methylation at 148 CpGs partly mapping to genes previously implicated in processes related to anxiety, brain disorders, learning or plasticity (e.g., GABBR2 , GABRD , GAST , IL12RB2 , LINC00293 , LOC101928626 , MFGE8 , NOTCH4 , PTPRN2 , RIMBP2 , SPTBN1 ) or in a recent cross-anxiety disorders EWAS ( TAOK1 ) after pre-processing and quality control ( N = 378 vs. N = 295). Furthermore, BL DNA methylation at seven and three CpGs, respectively, was suggestively ( p < 1E–5) associated with treatment response at POST ( ABCA7 , ADRA2C , LTBR , RPSAP52 , SH3RF3 , SLC47A2 , ZNF251 ) and FU ( ADGRD1 , PRSS58 , USP47 ). Finally, suggestive evidence for dynamic epigenome-wide DNA methylation changes along with CBT response emerged at four CpGs from BL to FU ( ADIPOR2 , EIF3B , OCA2 , TMCC1 ). The identification of epigenetic biomarkers may eventually aid in developing environment-based preventive strategies aimed at increasing resilience by providing deeper molecular insights into the mechanisms underlying anxiety disorders. Defining epigenetic signatures as predictors or key mechanisms in exposure-based interventions could pave the way for more targeted and personalized treatments for anxiety disorders.PROTECT‐AD (Providing Tools for Effective Care and Treatment of Anxiety Disorders“), Federal Ministry of Education and Research (BMBF; www.fzpe.de), grant number: 01EE1402Peer Reviewe
Predation Response of Macrolophus caliginosus Wagner (Hemiptera: Heteroptera: Miridae) Across Multiple Prey Density Levels of Aphis craccivora Under Fixed Temperature Conditions
No full textMacrolophus caliginosus Wagner (Hemiptera: Heteroptera: Miridae), a predatory bug widely used in biological control against whiteflies and spider mites, also shows strong efficiency on aphids, with females consuming on average ~43.2 first-instar Aphis gossypii nymphs per day under laboratory conditions. This study evaluates the predation capacity and functional response of M. caliginosus to varying densities of Aphis craccivora, aiming to assess its potential as a biological control agent against this significant agricultural pest. The research examines how each instar’s predation rate responds to three temperatures (20 °C, 25 °C, and 30 °C) and five prey density levels (5, 10, 15, 20, and 25). Predation rates were measured by exposing individual predators to different prey densities and recording the number of aphids consumed daily. Functional response parameters, including handling time (Th), search rate (α), and the average number of prey killed (Ha), were calculated using Holling’s disc equation. This study is a laboratory-based investigation conducted under controlled conditions. Macrolophus caliginosus nymphs showed a clear Type II functional response against Aphis craccivora, with first instars exhibiting the highest predation efficiency, consuming significantly more aphids than older instars, At 20 °C, predation capacity increased with prey density, peaking in the first instar and declining in later instars; at 25 °C, consumption patterns fluctuated, with reduced efficiency in higher instars; and at 30 °C, predation rates varied, with some instars showing improved efficiency. Functional response parameters revealed that the first instar had the shortest handling time at 20 °C, indicating high efficiency, while efficiency decreased at 25 °C and improved at 30 °C. The second instar showed enhanced predation at 25 °C but slightly reduced efficiency at 30 °C. The third instar exhibited high efficiency at 20 °C, declined at 25 °C, and partially recovered at 30 °C. The fourth instar consistently had the lowest predation rates and longest handling times across temperatures, improving efficiency at 30 °C; These findings underscore the interplay of temperature, prey density, and predator instars in determining predation rates. The data highlights the adaptability of M. caliginosus to environmental changes, providing critical insights for applications in biological pest control under varying climatic conditions.Open Access funding enabled and organized by Projekt DEAL.Humboldt-Universität zu Berlin (1034)Peer Reviewe
Unidirectional incentive compatibility
No full textWe study unidirectional incentive compatibility which incentivizes truth-telling by an agent who can misrepresent private information in one direction only. In the canonical setting with quasi-linear preferences and continuous, one-dimensional private information, we show that unidirectional incentive compatibility imposes no restrictions on the allocation rule and revenue equivalence fails. Moreover, unidirectional incentive compatibility holds if and only if the change of the agent’s information rent respects a lower bound based on the allocation rule’s monotone envelope. With strong interdependent values or countervailing incentives, optimal screening contracts differ from optimal bidirectionally incentive compatible contracts, possibly displaying non-monotone allocations.Peer Reviewe
A tris(pyrazolyl)-based model for the aminocyclopropane carboxylic acid oxidase and its behavior towards oxidants
No full textA low-molecular-weight analog of the 1-aminocyclopropane carboxylic acid oxidase (ACCO), [TpMesFeACC], 1, where the (His₂Asp)iron(II) moiety is mimicked by a hydrotris(3-mesitylpyrazol-1-yl)borato iron(II) unit, to which the natural substrate aminocyclopropane carboxylate is coordinated, has been accessed and structurally characterized. It was found to react slowly with O2 to yield the biological product ethylene. To create models of the intermediates proposed as part of the catalytic cycle of the ACCO 1 was treated with tBuOOH and mCPBA at low temperatures, which generated the respective FeIIIOOtBu and FeIV=O intermediates as shown by spectroscopic analysis. Studies on their behavior upon annealing reveal a non-biomimetic reactivity.Graphical AbstractOpen Access funding enabled and organized by Projekt DEAL.Deutsche Forschungsgemeinschafthttps://doi.org/10.13039/501100001659Humboldt-Universität zu Berlin (1034)Peer Reviewe
Household energy transition, fertility transition and women empowerment: linkages and opportunities for sustainable development
No full textDer Zugang zu moderner Energie bietet Dienstleistungen, die für die Befriedigung grundlegender menschlicher Bedürfnisse unerlässlich sind. Während Es ist zwar weithin anerkannt, dass sich der Zugang zu moderner Energie besonders positiv auf das Wohlergehen von Frauen auswirkt, doch seine Auswirkungen auf die reproduktive Gesundheit und die Fertilität sind noch nicht ausreichend untersucht worden. In dieser Arbeit habe ich die Auswirkungen der Energiewende in den Haushalten auf die Fertilität in in Ländern mit niedrigem bis mittlerem Einkommen, die Rolle der Frauen und die Auswirkungen dieser Beziehungen auf die Erreichung der Ziele für nachhaltige Entwicklung. Nach der Erstellung eines theoretischen Rahmens habe ich gezeigt, dass der Zugang von Frauen zu Elektrizität und modernen Kochbrennstoffen in 44 Ländern negativ mit der Fertilitätsrate verbunden ist und nach der Bildung der Frauen der stärkste Faktor für den Fertilitätsrückgang ist. In einer Fallstudie für Sambia habe ich herausgefunden, dass die Gesamtenergienachfrage um 27 % niedriger wäre als in einem Basisszenario, wenn die gesamte Bevölkerung Zugang zu moderner Energie hätte, und dass ein geringeres Bevölkerungswachstum aufgrund des universellen Energiezugangs bis 2050 zu einer Verringerung der Energienachfrage um 55 % gegenüber dem Basisszenario beiträgt. Insgesamt zeigt diese Arbeit, dass der universelle Zugang zu Energie mit den Zielen des Klimaschutzes und der reproduktiven Gesundheit und Rechte synergetisch ist. Ich plädiere für eine stärkere Berücksichtigung des Zusammenhangs zwischen Energie und Fertilität in der demografischen Forschung. Die Einbeziehung dieses Zusammenhangs in Energiemodelle kann wichtige Möglichkeiten aufzeigen, die Herausforderungen der Armut mit geringen Energie- und Kohlenstoffkosten anzugehen und gleichzeitig zur Gleichstellung der Geschlechter und zum Aufbau von Klimaresilienz beizutragen.Access to modern energy provides services that are essential for meeting basic human needs. While it is widely recognized that access to modern energy is particularly beneficial to women’s well-being, its impact on reproductive health and fertility has not been well studied. In this thesis, I examined the impact of household energy transition on fertility change in low- to middle-income countries, how women’s empowerment comes into play, and the implications of these relationships for achieving sustainable development goals. After laying the theoretical groundwork (Chapter 1) and constructing an international micro-dataset (Chapter 2), I used statistical analyses to show that women’s access to electricity and modern cooking fuels is negatively associated with fertility rates in 44 countries (Chapter 3), and is the strongest factor of fertility decline after women’s education. I then used a microsimulation model to project population and energy demand in Zambia. I found that if the entire population of Zambia had access to modern energy, total energy demand would be 27% lower than in a baseline scenario. I also found that reduced population growth due to universal energy access contributes to a 55% reduction in energy demand by 2050 compared to baseline scenario (Chapter 4). Finally, I provided a perspective piece that argues that planning for energy systems that are resilient to climate impacts is critical to reaping the benefits of the household energy transition for women’s empowerment and sustainable development (Chapter 5). Overall, this thesis shows that universal energy access is synergistic with climate protection and reproductive health and rights goals. I argue for greater attention to the energy-fertility nexus in demographic research. Incorporating this relationship into energy models can reveal important opportunities to address poverty challenges at low energy and carbon costs, while contributing to gender equality and building climate resilience