334 research outputs found

    Activity pattern and fat accumulation strategy of the Natterer’s bat (Vespertilionidae, Chiroptera) swarming population indicate the exact time of male mating effort

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    Studies concerning bat autumn swarming behavior suggest that the main purpose of this phenomenon is mating. However, the process of fat accumulation is crucial for surviving winter, and it seems to be in clear conflict with a need to strive for the opportunity to mate prior to hibernation. Investment in one activity limits the other one creating a trade-off between them. The aim of our study was to describe the activity pattern of each sex-age group (adult males, adult females, subadults) of the Natterer’s bat during swarming period and to investigate the fat accumulation process of adult males in the context of their reproductive strategy. Bats were captured by mist nets at the swarming site fortnightly from the early August until the late November. The age, sex, reproductive status, and body condition index (mass to forearm ratio, BCI) were recorded. The activity peak of both sexes, adults, and subadults was observed in the late September. That time in season, BCI of adult males was the lowest, and there was no correlation between the hour of an adult male capture and its BCI value within one night (rs = 0.23; p = 0.157). Such correlation was observed later in the season (early October: rs = 0.44; p = 0.020; late October: rs = 0.48; p = 0.002). A negative correlation between adult males’ BCI and proportion of adult females was found (r = 0.44; p = 0.000). We conclude that the activity peak of females is likely to be responsible for the effort of the mating behavior of the males, which is reflected by their low condition index. We suggest that the gleaning foraging strategy of Natterer’s bat allows the males to postpone their fat accumulation until just before hibernation

    Zirconium-based metal–organic frameworks as acriflavine cargos in the battle against coronaviruses : a theoretical and experimental approach

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    [Image: see text] In this study, we present a complementary approach for obtaining an effective drug, based on acriflavine (ACF) and zirconium-based metal–organic frameworks (MOFs), against SARS-CoV-2. The experimental results showed that acriflavine inhibits the interaction between viral receptor-binding domain (RBD) of spike protein and angiotensin converting enzyme-2 (ACE2) host receptor driving viral cell entry. The prepared ACF@MOF composites exhibited low (MOF-808 and UiO-66) and high (UiO-67 and NU-1000) ACF loadings. The drug release profiles from prepared composites showed different release kinetics depending on the local pore environment. The long-term ACF release with the effective antiviral ACF concentration was observed for all studied ACF@MOF composites. The density functional theory (DFT) calculations allowed us to determine that π–π stacking together with electrostatic interaction plays an important role in acriflavine adsorption and release from ACF@MOF composites. The molecular docking results have shown that acriflavine interacts with several possible binding sites within the RBD and binding site at the RBD/ACE2 interface. The cytotoxicity and ecotoxicity results have confirmed that the prepared ACF@MOF composites may be considered potentially safe for living organisms. The complementary experimental and theoretical results presented in this study have confirmed that the ACF@MOF composites may be considered a potential candidate for the COVID-19 treatment, which makes them good candidates for clinical trials

    Water-stable zirconium-based metal-organic framework material with high-surface area and gas-storage capacities.

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    We designed, synthesized, and characterized a new Zr-based metal-organic framework material, NU-1100, with a pore volume of 1.53 ccg(-1) and Brunauer-Emmett-Teller (BET) surface area of 4020 m(2) g(-1) ; to our knowledge, currently the highest published for Zr-based MOFs. CH4 /CO2 /H2 adsorption isotherms were obtained over a broad range of pressures and temperatures and are in excellent agreement with the computational predictions. The total hydrogen adsorption at 65 bar and 77 K is 0.092 g g(-1) , which corresponds to 43 g L(-1) . The volumetric and gravimetric methane-storage capacities at 65 bar and 298 K are approximately 180 vSTP /v and 0.27 g g(-1) , respectively.OKF, JTH and RQS thank DOE ARPA-E and the Stanford Global Climate and Energy Project for support of work relevant to methane and CO2, respectively. TY acknowledges support by the U. S. Department of Energy through BES Grant No. DE-FG02-08ER46522. WB acknowledges support from the Foundation for Polish Science through the “Kolumb” Program. DFJ acknowledges the Royal Society (UK) for a University Research Fellowship. This material is based upon work supported by the National Science Foundation (grant CHE-1048773).This is the accepted manuscript. The final version is available as 'Water-Stable Zirconium-Based Metal–Organic Framework Material with High-Surface Area and Gas-Storage Capacities' from Wiley at http://onlinelibrary.wiley.com/doi/10.1002/chem.201402895/abstract

    From Chalcogen Bonding to S–π Interactions in Hybrid Perovskite Photovoltaics

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    The stability of hybrid organic–inorganic halide perovskite semiconductors remains a significant obstacle to their application in photovoltaics. To this end, the use of low‐dimensional (LD) perovskites, which incorporate hydrophobic organic moieties, provides an effective strategy to improve their stability, yet often at the expense of their performance. To address this limitation, supramolecular engineering of noncovalent interactions between organic and inorganic components has shown potential by relying on hydrogen bonding and conventional van der Waals interactions. Here, the capacity to access novel LD perovskite structures that uniquely assemble through unorthodox S‐mediated interactions is explored by incorporating benzothiadiazole‐based moieties. The formation of S‐mediated LD structures is demonstrated, including one‐dimensional (1D) and layered two‐dimensional (2D) perovskite phases assembled via chalcogen bonding and S–π interactions, through a combination of techniques, such as single crystal and thin film X‐ray diffraction, as well as solid‐state NMR spectroscopy, complemented by molecular dynamics simulations, density functional theory calculations, and optoelectronic characterization, revealing superior conductivities of S‐mediated LD perovskites. The resulting materials are applied in n‐i‐p and p‐i‐n perovskite solar cells, demonstrating enhancements in performance and operational stability that reveal a versatile supramolecular strategy in photovoltaics

    From Chalcogen Bonding to S–π Interactions in Hybrid Perovskite Photovoltaics

    Get PDF
    The stability of hybrid organic–inorganic halide perovskite semiconductors remains a significant obstacle to their application in photovoltaics. To this end, the use of low‐dimensional (LD) perovskites, which incorporate hydrophobic organic moieties, provides an effective strategy to improve their stability, yet often at the expense of their performance. To address this limitation, supramolecular engineering of noncovalent interactions between organic and inorganic components has shown potential by relying on hydrogen bonding and conventional van der Waals interactions. Here, the capacity to access novel LD perovskite structures that uniquely assemble through unorthodox S‐mediated interactions is explored by incorporating benzothiadiazole‐based moieties. The formation of S‐mediated LD structures is demonstrated, including one‐dimensional (1D) and layered two‐dimensional (2D) perovskite phases assembled via chalcogen bonding and S–π interactions, through a combination of techniques, such as single crystal and thin film X‐ray diffraction, as well as solid‐state NMR spectroscopy, complemented by molecular dynamics simulations, density functional theory calculations, and optoelectronic characterization, revealing superior conductivities of S‐mediated LD perovskites. The resulting materials are applied in n‐i‐p and p‐i‐n perovskite solar cells, demonstrating enhancements in performance and operational stability that reveal a versatile supramolecular strategy in photovoltaics

    Performance of the CMS muon trigger system in proton-proton collisions at √s = 13 TeV

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    The muon trigger system of the CMS experiment uses a combination of hardware and software to identify events containing a muon. During Run 2 (covering 2015-2018) the LHC achieved instantaneous luminosities as high as 2 × 10 cm s while delivering proton-proton collisions at √s = 13 TeV. The challenge for the trigger system of the CMS experiment is to reduce the registered event rate from about 40 MHz to about 1 kHz. Significant improvements important for the success of the CMS physics program have been made to the muon trigger system via improved muon reconstruction and identification algorithms since the end of Run 1 and throughout the Run 2 data-taking period. The new algorithms maintain the acceptance of the muon triggers at the same or even lower rate throughout the data-taking period despite the increasing number of additional proton-proton interactions in each LHC bunch crossing. In this paper, the algorithms used in 2015 and 2016 and their improvements throughout 2017 and 2018 are described. Measurements of the CMS muon trigger performance for this data-taking period are presented, including efficiencies, transverse momentum resolution, trigger rates, and the purity of the selected muon sample. This paper focuses on the single- and double-muon triggers with the lowest sustainable transverse momentum thresholds used by CMS. The efficiency is measured in a transverse momentum range from 8 to several hundred GeV

    Porous Silsesquioxane–Imine Frameworks as Highly Efficient Adsorbents for Cooperative Iodine Capture

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    The efficient capture and storage of radioactive iodine (<sup>129</sup>I or <sup>131</sup>I), which can be formed during nuclear energy generation or nuclear waste storage, is of paramount importance. Herein, we present highly efficient aerogels for reversible iodine capture, namely, porous silsesquioxane–imine frameworks (PSIFs), constructed by condensation of octa­(3-aminopropyl)­silsesquioxane cage compound and selected multitopic aldehydes. The resulting PSIFs are permanently porous (Brunauer–Emmet–Teller surface areas up to 574 m<sup>2</sup>/g), thermally stable, and present a combination of micro-, meso-, and macropores in their structures. The presence of a large number of imine functional groups in combination with silsesquioxane cores results in extremely high I<sub>2</sub> affinity with uptake capacities up to 485 wt %, which is the highest reported to date. Porous properties can be controlled by the strut length and rigidity of linkers. In addition, <b>PSIF-1a</b> could be recycled at least four times while maintaining 94% I<sub>2</sub> uptake capacity. Kinetic studies of I<sub>2</sub> desorption show two strong binding sites with apparent activation energies of 77.0 and 89.0 kJ/mol. These energies are considerably higher than the enthalpy of sublimation of bulk I<sub>2</sub>
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