2,170 research outputs found
Pancake bouncing on superhydrophobic surfaces
Engineering surfaces that promote rapid drop detachment is of importance to a
wide range of applications including anti-icing, dropwise condensation6, and
self-cleaning. Here we show how superhydrophobic surfaces patterned with
lattices of submillimetre-scale posts decorated with nano-textures can generate
a counter-intuitive bouncing regime: drops spread on impact and then leave the
surface in a flattened, pancake shape without retracting. This allows for a
four-fold reduction in contact time compared to conventional complete rebound.
We demonstrate that the pancake bouncing results from the rectification of
capillary energy stored in the penetrated liquid into upward motion adequate to
lift the drop. Moreover, the timescales for lateral drop spreading over the
surface and for vertical motion must be comparable. In particular, by designing
surfaces with tapered micro/nanotextures which behave as harmonic springs, the
timescales become independent of the impact velocity, allowing the occurrence
of pancake bouncing and rapid drop detachment over a wide range of impact
velocities.Comment: 11 pages, 4 figures, 31 references, + 5 pages of supplementary
informatio
Tracking 21st century anthropogenic and natural carbon fluxes through model-data integration
Monitoring the implementation of emission commitments under the Paris agreement relies on accurate estimates of terrestrial carbon fluxes. Here, we assimilate a 21st century observation-based time series of woody vegetation carbon densities into a bookkeeping model (BKM). This approach allows us to disentangle the observation-based carbon fluxes by terrestrial woody vegetation into anthropogenic and environmental contributions. Estimated emissions (from land-use and land cover changes) between 2000 and 2019 amount to 1.4 PgC yr ā1 , reducing the difference to other carbon cycle model estimates by up to 88% compared to previous estimates with the BKM (without the data assimilation). Our estimates suggest that the global woody vegetation carbon sink due to environmental processes (1.5 PgC yr ā1 ) is weaker and more susceptible to interannual variations and extreme events than estimated by state-of-the-art process-based carbon cycle models. These findings highlight the need to advance model-data integration to improve estimates of the terrestrial carbon cycle under the Global Stocktake
Temporal Evolution of Island Arc Magmatism and Its Influence on Long-Term Climate: Insights From the Izu Intra-Oceanic Arc
Continental arcs have an episodic magmatic activity over long-time periods, which is believed to modulate long-term climate. Island arcs have also the potential to release large amount of CO2 into the atmosphere, but whether they display an episodic magmatic history throughout their lifespan that contributes to the long-term (>10Ā Ma) climate changes remains an open question. To set additional constraints on the magmatic history of island arcs, here we examine fresh basalts and mineral-hosted melt inclusions from the Izu intra-oceanic arc, shortly after the eruption of boninites (ā¼45Ā Ma ago). Using chemical markers, we show that the long-term magmatic activity of the mature Izu arc has been relatively continuous over its lifespan, except during opening of the Shikoku back-arc Basin (ā¼23ā20Ā Ma). Because slab dehydration and slab melting trigger decarbonation and carbonate dissolution of the subducted plate, we use slab-fluid markers (Ba/Th, Cs/Th, Cs/Ba, Rb/Th, Th/Nb) to examine the variations of slab-derived CO2 captured by the arc magmas. The long-term steadiness in the arc magmatic activity and in the slab-fluid contribution suggests that the CO2 outgassed during mature arc volcanism may have remained relatively homogeneous for the past 40Ā Ma in Izu. If worldwide mature island arcs also maintain a relatively steady-state magmatic activity over their lifespan, the long-term CO2 outgassed by these arc volcanoes may be rapidly balanced by chemical weathering and tectonic erosion, which rapidly draw down the atmospheric CO2 (within 200ā300 kyr). This rapid negative feedback to long-term volcanic degassing permits to sustain a viable atmospheric CO2 for millions of years. The lack of co-variations between the markers of climate changes (Ī“13O, Ī“18C) and the long-term averages of the markers of slab fluids further implies that long-term volcanic degassing of CO2 from mature island arcs might play a minor role in the slide into icehouse climatic conditions. This long-term degassing stability may be, instead, a contributor to maintaining a broadly stable climate over long timescales
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Local lung hypoxia determines epithelial fate decisions during alveolar regeneration.
After influenza infection, lineage-negative epithelial progenitors (LNEPs) exhibit a binary response to reconstitute epithelial barriers: activating a Notch-dependent ĪNp63/cytokeratin 5 (Krt5) remodelling program or differentiating into alveolar type II cells (AEC2s). Here we show that local lung hypoxia, through hypoxia-inducible factor (HIF1Ī±), drives Notch signallingĀ andĀ Krt5pos basal-like cell expansion. Single-cell transcriptional profiling of human AEC2s from fibrotic lungs revealed a hypoxic subpopulation with activated Notch, suppressed surfactant protein C (SPC), and transdifferentiation toward a Krt5pos basal-likeĀ state. Activated murine Krt5pos LNEPs and diseased human AEC2s upregulate strikingly similar core pathways underlyingĀ migration and squamous metaplasia. While robust, HIF1Ī±-driven metaplasia is ultimately inferior to AEC2 reconstitution inĀ restoring normal lung function. HIF1Ī± deletion or enhanced Wnt/Ī²-catenin activity in Sox2pos LNEPs blocks Notch andĀ Krt5Ā activation, instead promoting rapid AEC2 differentiation and migration and improving the quality of alveolar repair
High-dose influenza vaccination and mortality among predominantly male, white, senior veterans, United States, 2012/13 to 2014/15
Introduction: It is unclear whether high- dose influenza vaccine (HD) is more effective at reducing mortality among seniors. Aim: This study aimed to evaluate the relative vaccine effectiveness (rVE) of HD. Methods: We linked electronic medical record databases in the Veterans Health Administration (VHA) and Medicare administrative files to examine the rVE of HD vs standard- dose influenza vaccines (SD) in preventing influenza/pneumonia-associated and cardiorespiratory mortality among VHA-enrolled veterans 65 years or older during the 2012/13, 2013/14 and 2014/15 influenza seasons. A multivariable Cox proportional hazards model was performed on matched recipients of HD vs SD, based on vaccination time, location, age, sex, ethnicity and VHA priority level. Results: Among 569,552 person-seasons of observation, 207,574 (36%) were HD recipients and 361,978 (64%) were SD recipients, predominantly male (99%) and white (82%). Pooling findings from all three seasons, the adjusted rVE estimate of HD vs SD during the high influenza periods was 42% (95% confidence interval (CI): 24-59) against influenza/pneumonia-associated mortality and 27% (95% CI: 23-32) against cardiorespiratory mortality. Residual confounding was evident in both early and late influenza periods despite matching and multivariable adjustment. Excluding individuals with high 1-year predicted mortality at baseline reduced the residual confounding and yielded rVE of 36% (95% CI: 10-62) and 25% (95% CI: 12-38) against influenza/pneumonia-associated and cardiorespiratory mortality, respectively. These were confirmed by results from two-stage residual inclusion estimations. Discussion: The HD was associated with a lower risk of influenza/pneumonia-associated and cardiorespiratory death in men during the high influenza period
A bony-crested Jurassic dinosaur with evidence of iridescent plumage highlights complexity in early paravian evolution
The Jurassic Yanliao theropods have offered rare glimpses of the early paravian evolution and particularly of bird origins, but, with the exception of the bizarre scansoriopterygids, they have shown similar skeletal and integumentary morphologies. Here we report a distinctive new Yanliao theropod species bearing prominent lacrimal crests, bony ornaments previously known from more basal theropods. It shows longer arm and leg feathers than Anchiornis and tail feathers with asymmetrical vanes forming a tail surface area even larger than that in Archaeopteryx. Nanostructures, interpreted as melanosomes, are morphologically similar to organized, platelet-shaped organelles that produce bright iridescent colours in extant birds. The new species indicates the presence of bony ornaments, feather colour and flight- related features consistent with proposed rapid character evolution and significant diversity in signalling and locomotor strategies near bird origins
Kinematic Distances to Molecular Clouds identified in the Galactic Ring Survey
Kinematic distances to 750 molecular clouds identified in the 13CO J=1-0
Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey
(BU-FCRAO GRS) are derived assuming the Clemens rotation curve of the Galaxy.
The kinematic distance ambiguity is resolved by examining the presence of HI
self-absorption toward the 13CO emission peak of each cloud using the Very
Large Array Galactic Plane Survey (VGPS). We also identify 21 cm continuum
sources embedded in the GRS clouds in order to use absorption features in the
HI 21 cm continuum to distinguish between near and far kinematic distances. The
Galactic distribution of GRS clouds is consistent with a four-arm model of the
Milky Way. The locations of the Scutum-Crux and Perseus arms traced by GRS
clouds match star count data from the Galactic Legacy Infrared Mid-Plane Survey
Extraordinaire (GLIMPSE) star-count data. We conclude that molecular clouds
must form in spiral arms and be short-lived (lifetimes < 10 Myr) in order to
explain the absence of massive, 13CO bright molecular clouds in the inter-arm
space
Design, synthesis, and evaluation of substituted nicotinamide adenine dinucleotide (NAD+) synthetase inhibitors as potential antitubercular agents
Nicotinamide adenine dinucleotide (NAD+) synthetase catalyzes the last step in NAD+ biosynthesis. Depletion of NAD+ is bactericidal for both active and dormant Mycobacterium tuberculosis (Mtb). By inhibiting NAD+ synthetase (NadE) from Mtb, we expect to eliminate NAD+ production which will result in cell death in both growing and nonreplicating Mtb. NadE inhibitors have been investigated against various pathogens, but few have been tested against Mtb. Here, we report on the expansion of a series of urea-sulfonamides, previously reported by Brouillette et al. Guided by docking studies, substituents on a terminal phenyl ring were varied to understand the structure-activity-relationships of substituents on this position. Compounds were tested as inhibitors of both recombinant Mtb NadE and Mtb whole cells. While the parent compound displayed very weak inhibition against Mtb NadE (IC50=1000ĀµM), we observed up to a 10-fold enhancement in potency after optimization. Replacement of the 3,4-dichloro group on the phenyl ring of the parent compound with 4-nitro yielded 4f, the most potent compound of the series with an IC50 value of 90ĀµM against Mtb NadE. Our modeling results show that these urea-sulfonamides potentially bind to the intramolecular ammonia tunnel, which transports ammonia from the glutaminase domain to the active site of the enzyme. This hypothesis is supported by data showing that, even when treated with potent inhibitors, NadE catalysis is restored when treated with exogenous ammonia. Most of these compounds also inhibited Mtb cell growth with MIC values of 19-100Āµg/mL. These results improve our understanding of the SAR of the urea-sulfonamides, their mechanism of binding to the enzyme, and of Mtb NadE as a potential antitubercular drug target
Three-Dimensional Au Microlattices as Positive Electrodes for LiāO_2 Batteries
We demonstrate the feasibility of using a 3-dimensional gold microlattice with a periodic porous structure and independently tunable surface composition as a LiāO_2 battery cathode. The structure provides a platform for studying electrochemical reactions in architected LiāO_2 electrodes with large (300 Ī¼m) pore sizes. The lack of carbon and chemical binders in these Au microlattices enabled the investigation of chemical and morphological processes that occur on the surfaces of the microlattice during cycling. LiāO_2 cells with Au microlattice cathodes were discharged in 0.5 M lithium-bis(trifluoromethane)sulfonamide (LiTFSI) in a 1,2-dimethoxyethane (DME) electrolyte, with lithium metal foil as the anode. SEM analysis of microlattice cathodes after first discharge revealed the presence of toroidal-shaped 500ā700 nm particles covering the surface of the electrode, which disappeared upon subsequent charging. Raman and FTIR spectroscopy analysis determined these particulates to be Li_2O_2. The morphology of discharge products evolved with cycling into micrometer-sized clusters of arranged āplateletsā, with a higher amount of side reaction products such as Li_2CO_3 and LiOH. This work shows that properly designed 3-dimensional architected materials may provide a useful foundation for investigating fundamental surface electrochemistry while simultaneously enabling mechanical robustness and enhancing the surface area over a factor of 30 compared with a thin film with the same foot print
OXYGEN REACTIVE POLYMERS FOR TREATMENT OF TRAUMATIC BRAIN INJURY
Methods and compositions for treating traumatic brain injury . The methods and compositions utilize a multi - functional oxygen reactive polymer ( ORP ) that includes repeating units that include a reactive oxygen species ( ROS ) scavenging group and a polyalkylene oxide group . For theranostic applications , the oxygen reactive polymer fur ther includes a diagnostic group
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