334 research outputs found
Activity pattern and fat accumulation strategy of the Nattererâs bat (Vespertilionidae, Chiroptera) swarming population indicate the exact time of male mating effort
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 Nattererâs 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 malesâ 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 Nattererâs bat allows the males to postpone their fat accumulation until just before hibernation
Zirconium-based metalâorganic frameworks as acriflavine cargos in the battle against coronaviruses : a theoretical and experimental approach
[Image: see text] In this study, we present a complementary approach for obtaining an effective drug, based on acriflavine (ACF) and zirconium-based metalâorganic 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 ÏâÏ 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.
We designed, synthesized, and characterized a new Zr-based metal-organic framework material, NU-1100, with a pore volume of 1.53â
ccg(-1) and Brunauer-Emmett-Teller (BET) surface area of 4020â
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 65â
bar and 77â
K is 0.092â
gâg(-1) , which corresponds to 43â
gâL(-1) . The volumetric and gravimetric methane-storage capacities at 65â
bar and 298â
K are approximately 180â
vSTP /v and 0.27â
gâg(-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 âKolumbâ 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 MetalâOrganic 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 SâÏ Interactions in Hybrid Perovskite Photovoltaics
The stability of hybrid organicâinorganic halide perovskite semiconductors remains a significant obstacle to their application in photovoltaics. To this end, the use of lowâdimensional (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 Sâmediated interactions is explored by incorporating benzothiadiazoleâbased moieties. The formation of Sâmediated LD structures is demonstrated, including oneâdimensional (1D) and layered twoâdimensional (2D) perovskite phases assembled via chalcogen bonding and SâÏ interactions, through a combination of techniques, such as single crystal and thin film Xâray diffraction, as well as solidâstate NMR spectroscopy, complemented by molecular dynamics simulations, density functional theory calculations, and optoelectronic characterization, revealing superior conductivities of Sâmediated LD perovskites. The resulting materials are applied in nâiâp and pâiân perovskite solar cells, demonstrating enhancements in performance and operational stability that reveal a versatile supramolecular strategy in photovoltaics
From Chalcogen Bonding to SâÏ Interactions in Hybrid Perovskite Photovoltaics
The stability of hybrid organicâinorganic halide perovskite semiconductors remains a significant obstacle to their application in photovoltaics. To this end, the use of lowâdimensional (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 Sâmediated interactions is explored by incorporating benzothiadiazoleâbased moieties. The formation of Sâmediated LD structures is demonstrated, including oneâdimensional (1D) and layered twoâdimensional (2D) perovskite phases assembled via chalcogen bonding and SâÏ interactions, through a combination of techniques, such as single crystal and thin film Xâray diffraction, as well as solidâstate NMR spectroscopy, complemented by molecular dynamics simulations, density functional theory calculations, and optoelectronic characterization, revealing superior conductivities of Sâmediated LD perovskites. The resulting materials are applied in nâiâp and pâiân 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 âs = 13 TeV
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 Ă 10 cm s while delivering proton-proton collisions at âs = 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 SilsesquioxaneâImine Frameworks as Highly Efficient Adsorbents for Cooperative Iodine Capture
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 silsesquioxaneâimine frameworks (PSIFs), constructed
by condensation of octaÂ(3-aminopropyl)Âsilsesquioxane cage compound
and selected multitopic aldehydes. The resulting PSIFs are permanently
porous (BrunauerâEmmetâTeller 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>
- âŠ