A number of studies indicate that tropical arthropods should be particularly vulnerable to climate warming. If these predictions are realized, climate warming may have a more profound impact on the ...functioning and diversity of tropical forests than currently anticipated. Although arthropods comprise over two-thirds of terrestrial species, information on their abundance and extinction rates in tropical habitats is severely limited. Here we analyze data on arthropod and insectivore abundances taken between 1976 and 2012 at two midelevation habitats in Puerto Rico’s Luquillo rainforest. During this time, mean maximum temperatures have risen by 2.0 °C. Using the same study area and methods employed by Lister in the 1970s, we discovered that the dry weight biomass of arthropods captured in sweep samples had declined 4 to 8 times, and 30 to 60 times in sticky traps. Analysis of long-term data on canopy arthropods and walking sticks taken as part of the Luquillo Long-Term Ecological Research program revealed sustained declines in abundance over two decades, as well as negative regressions of abundance on mean maximum temperatures. We also document parallel decreases in Luquillo’s insectivorous lizards, frogs, and birds. While El Niño/Southern Oscillation influences the abundance of forest arthropods, climate warming is the major driver of reductions in arthropod abundance, indirectly precipitating a bottom-up trophic cascade and consequent collapse of the forest food web.
The potential of merging photoredox and nickel catalysis to perform multicomponent alkene difunctionalizations under visible‐light irradiation is demonstrated here. Secondary and tertiary alkyl ...groups, as well as sulfonyl moieties can be added to the terminal position of the double bond with simultaneous arylation of the internal carbon atom in a single step under mild reaction conditions. The process, devoid of stoichiometric additives, benefits from the use of bench‐stable and easy‐to‐handle reagents, is operationally simple, and tolerates a wide variety of functional groups.
A cut of π: Demonstrated here is the use of a dual Ru/Ni catalytic system in a three‐component carbofunctionalization of alkenes under visible‐light irradiation. The method allows the simultaneous and regiocontrolled addition of aromatic groups together with either sulfonyl or alkyl groups across the π system with readily available, bench‐top stable sulfinate and alkylsilicate partners.
In recent years, cellular automata (CA) models for urban growth simulation have proliferated because of their simplicity, flexibility and intuitiveness, and particularly because of their ability to ...incorporate the spatial and temporal dimensions of the processes. Though apparently simple, CA models are capable of modeling complex dynamic systems such as urban systems. Currently, one of the main problems in actually applying CA models to urban planning practice is the choice or design of the most suitable CA model. For this reason, a review of urban CA models applied to real-world cases is provided, along with an analysis of their capabilities and limitations. The review and classification of CA models based on the main characteristics of the models has allowed for the analysis of their strengths and weaknesses. Finally, a discussion of the needs for further research is presented.
ABSTRACT
We study the effects of galaxy formation physics on the magnetization of the intergalactic medium (IGM) using the IllustrisTNG simulations. We demonstrate that large-scale regions affected ...by the outflows from galaxies and clusters contain magnetic fields that are several orders of magnitude stronger than in unaffected regions with the same electron density. Moreover, like magnetic fields amplified inside galaxies, these magnetic fields do not depend on the primordial seed, i.e. the adopted initial conditions for magnetic field strength. We study the volume filling fraction of these strong field regions and their occurrence in random lines of sight. As a first application, we use these results to put bounds on the photon–axion conversion from spectral distortion of the CMB. As photon–axion coupling grows with energy, stronger constraints could potentially be obtained using data on the propagation of gamma-ray photons through the IGM. Finally, we also briefly discuss potential applications of our results to the Faraday Rotation measurements.
This paper aims to study the factors determining the quality of sustainability reporting in Latin American business groups. Applying a logistic regression model, this study is pioneer in establishing ...how some distinct corporate variables of business groups influence disclosure quality of Corporate Social Responsibility practices in these groups in emerging economies. The results show that control concentration in the groups negatively affects the quality of sustainability reporting. Variables such as foreign ownership, the age of the business group and board size help business groups to improve the quality of their sustainability and voluntary disclosure practices. These results form the basis to conduct further studies on voluntary disclosure in business groups, since they evidence that corporate governance has implications for the group’s sustainability and their voluntary disclosure, especially in the institutional context of developing economies where sustainability is an emerging topic in its link with the nature of the firm (business group).
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To replace glass-fiber sheet molding compound (GF-SMC) using natural fiber-reinforced composites (NFRCs) in the automotive industry, this work intended to enhance mechanical properties and water ...resistance of NFRCs by impregnating magnesium hydroxide (MH) to kenaf fibers and fabricating composites using the vacuum bag resin transfer molding (VBRTM) technology. The modulus of rupture and tensile strength of modified composites were significantly increased by 73.9% and 54.6% compared with that of the regular NFRCs, respectively. Based on the scanning electron microscope observation, it was found that the MH impregnation significantly enhanced the compatibility of kenaf fibers and polymer matrix, benefiting to the mechanical-property improvements of the composites. Compared to the regular NFRC, the 24-h water absorption and thickness swelling of MH impregnated NFRC (MH-NFRC) were significantly reduced by 83.9% and 84.2%, respectively. When the composite density was factored in the comparison of MH-NFRC and GF-SMC, the specific modulus of rupture and tensile strength of MH-NFRC were 116.4% and 109.0% of the GF-SMC, respectively. Apart from the mechanical properties, the advantages of replacing GF-SMC by MH-NFRC were reflected in the reductions of energy consumption and environmental impacts. It was calculated that the energy consumption of fabricating MH-NFRC was decreased by 33.1% compared with GF-SMC. The comparisons of environmental impacts of MH-NFRC and GF-SMC were performed by life-cycle assessment (LCA) using the SimaPro software. The results demonstrated that the environmental burdens of the composites were reduced by 22.8%, when kenaf fibers were used. All major indices of environmental impacts of MH-NFRC, including the total Global warming, Acidification, Human Health (HH) cancer, HH noncancer, HH criteria air pollutants, Eutrophication, Ecotoxicity, Smog, Natural resource depletion, Habitat alteration, Water intake and Ozone depletion, were reduced by 13.66–51.91%, respectively. It was concluded that the newly developed NFRC had great potential for replacing the GF-SMC in automobile applications, with reduced energy consumption and environmental impacts.
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•Composites were fabricated using Mg(OH)2 impregnated kenaf fibers and polyester.•Dramatically enhanced mechanical properties using Mg(OH)2-impregnated fibers.•Comparable properties with automotive glass-fiber sheet molding compound (GF-SMC).•Energy consumption was decreased by 33.1% compared with GF-SMC.•Environmental impact was reduced by 22.8% from life-cycle assessment.
Xe is only produced by cryogenic distillation of air, and its availability is limited by the extremely low abundance. Therefore, Xe recovery after usage is the only way to guarantee sufficient supply ...and broad application. Herein we demonstrate DD3R zeolite as a benchmark membrane material for CO2/Xe separation. The CO2 permeance after an optimized membrane synthesis is one order magnitude higher than for conventional membranes and is less susceptible to water vapour. The overall membrane performance is dominated by diffusivity selectivity of CO2 over Xe in DD3R zeolite membranes, whereby rigidity of the zeolite structure plays a key role. For relevant anaesthetic composition (<5 % CO2) and condition (humid), CO2 permeance and CO2/Xe selectivity stabilized at 2.0×10−8 mol m−2 s−1 Pa−1 and 67, respectively, during long‐term operation (>320 h). This endows DD3R zeolite membranes great potential for on‐stream CO2 removal from the Xe‐based closed‐circuit anesthesia system. The large cost reduction of up to 4 orders of magnitude by membrane Xe‐recycling (>99+%) allows the use of the precious Xe as anaesthetics gas a viable general option in surgery.
Hydrophobic DD3R zeolite is a benchmark membrane material for Xe recovery. The CO2 permeance is one order magnitude higher than conventional membranes and is less susceptible to humidity. The high performance and long‐term stability endow DD3R zeolite membranes great potential for on‐stream CO2 removal from the exhaled Xe‐based anaesthetic gas.
β,β‐Disubstituted vinyl sulfones were obtained with complete regio‐ and stereocontrol in a multicomponent reaction involving alkynes, organoboronic acids, and sulfonyl chlorides in the presence of a ...nickel catalyst. The reaction proceeds via sulfonyl radicals generated in situ under mild reaction conditions.
Running mild: Readily available alkynes, boronic acids, and sulfonyl chlorides can be combined in the presence of a Ni catalyst to produce β,β‐disubstituted vinyl sulfones with complete regio‐ and stereocontrol. The reaction proceeds via sulfonyl radicals generated in situ under mild reaction conditions and with high functional‐group tolerance.
The β1-adrenergic-receptor (ADRB1) antagonist metoprolol reduces infarct size in acute myocardial infarction (AMI) patients. The prevailing view has been that metoprolol acts mainly on ...cardiomyocytes. Here, we demonstrate that metoprolol reduces reperfusion injury by targeting the haematopoietic compartment. Metoprolol inhibits neutrophil migration in an ADRB1-dependent manner. Metoprolol acts during early phases of neutrophil recruitment by impairing structural and functional rearrangements needed for productive engagement of circulating platelets, resulting in erratic intravascular dynamics and blunted inflammation. Depletion of neutrophils, ablation of Adrb1 in haematopoietic cells, or blockade of PSGL-1, the receptor involved in neutrophil-platelet interactions, fully abrogated metoprolol's infarct-limiting effects. The association between neutrophil count and microvascular obstruction is abolished in metoprolol-treated AMI patients. Metoprolol inhibits neutrophil-platelet interactions in AMI patients by targeting neutrophils. Identification of the relevant role of ADRB1 in haematopoietic cells during acute injury and the protective role upon its modulation offers potential for developing new therapeutic strategies.
Effect of DNA Origami Nanostructures on Bacterial Growth Garcia‐Diosa, Jaime Andres; Grundmeier, Guido; Keller, Adrian
Chembiochem : a European journal of chemical biology,
April 2, 2024, Letnik:
25, Številka:
7
Journal Article
Recenzirano
Odprti dostop
DNA origami nanostructures are a powerful tool in biomedicine and can be used to combat drug‐resistant bacterial infections. However, the effect of unmodified DNA origami nanostructures on bacteria ...is yet to be elucidated. With the aim to obtain a better understanding of this phenomenon, the effect of three DNA origami shapes, i.e., DNA origami triangles, six‐helix bundles (6HBs), and 24‐helix bundles (24HBs), on the growth of Gram‐negative Escherichia coli and Gram‐positive Bacillus subtilis is investigated. The results reveal that while triangles and 24HBs can be used as a source of nutrients by E. coli and thereby promote population growth, their effect is much smaller than that of genomic single‐ and double‐stranded DNA. However, no effect on E. coli population growth is observed for the 6HBs. On the other hand, B. subtilis does not show any significant changes in population growth when cultured with the different DNA origami shapes or genomic DNA. The detailed effect of DNA origami nanostructures on bacterial growth thus depends on the competence signals and uptake mechanism of each bacterial species, as well as the DNA origami shape. This should be considered in the development of antimicrobial DNA origami nanostructures.
Bacteria can use DNA origami nanostructures as a nutrient source, leading to increased population growth. This process depends not only on the competence signal and uptake mechanisms of each species, but also on DNA origami shape and superstructure. It should thus be considered in the design and development of antimicrobial DNA origami nanostructures.
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