Recent theoretical proposals suggest that strain can be used to engineer graphene electronic states through the creation of a pseudo-magnetic field. This effect is unique to graphene because of its ...massless Dirac fermion-like band structure and particular lattice symmetry (C₃v). Here, we present experimental spectroscopic measurements by scanning tunneling microscopy of highly strained nanobubbles that form when graphene is grown on a platinum (111) surface. The nanobubbles exhibit Landau levels that form in the presence of strain-induced pseudo-magnetic fields greater than 300 tesla. This demonstration of enormous pseudo-magnetic fields opens the door to both the study of charge carriers in previously inaccessible high magnetic field regimes and deliberate mechanical control over electronic structure in graphene or so-called "strain engineering."
Observations of gravitational-wave signals from binary neutron-star mergers, like GW170817, can be used to constrain the neutron-star equation of state (EoS). One method involves modeling the EoS and ...measuring the model parameters through Bayesian inference. A previous study B. D. Lackey and L. Wade, Phys. Rev. D 91, 043002 (2015) has demonstrated the effectiveness of using a phenomenologically parameterized piecewise polytrope to extract constraining information from a simulated population of binary neutron-star mergers. Despite its advantages compared to more traditional methods of measuring the tidal deformability of neutron stars, notable deficiencies arise when using this EoS model. In this work, we describe in detail the implementation of a model built from a spectral decomposition of the adiabatic index that was used by the LIGO-Virgo Collaboration arXiv:1805.11581 to constrain the neutron-star EoS from GW170817. We demonstrate its overall consistency in recovering the neutron-star EoS from a simulated signal to the piecewise-polytropic implementation used by Lackey and Wade and explain any differences that arise. We find that both models recover consistent tidal information from the simulate signals with tightest constraints on the EoS around twice nuclear saturation density. As expected, the statistical error that arises in the piecewise-polytropic representation near the fixed joining densities is greatly reduced by using the spectral model. In addition, we find that our choice of prior can have a dominant effect on EoS constraints.
This article provides an overview of the current and projected climate change risks and impacts to mental health and provides recommendations for priority actions to address the mental health ...consequences of climate change.
The authors argue the following three points: firstly, while attribution of mental health outcomes to specific climate change risks remains challenging, there are a number of opportunities available to advance the field of mental health and climate change with more empirical research in this domain; secondly, the risks and impacts of climate change on mental health are already rapidly accelerating, resulting in a number of direct, indirect, and overarching effects that disproportionally affect those who are most marginalized; and, thirdly, interventions to address climate change and mental health need to be coordinated and rooted in active hope in order to tackle the problem in a holistic manner. This discussion paper concludes with recommendations for priority actions to address the mental health consequences of climate change.
Cobalt oxides and (oxy)hydroxides have been widely studied as electrocatalysts for the oxygen evolution reaction (OER). For related Ni-based materials, the addition of Fe dramatically enhances OER ...activity. The role of Fe in Co-based materials is not well-documented. We show that the intrinsic OER activity of Co1–x Fe x (OOH) is ∼100-fold higher for x ≈ 0.6–0.7 than for x = 0 on a per-metal turnover frequency basis. Fe-free CoOOH absorbs Fe from electrolyte impurities if the electrolyte is not rigorously purified. Fe incorporation and increased activity correlate with an anodic shift in the nominally Co2+/3+ redox wave, indicating strong electronic interactions between the two elements and likely substitutional doping of Fe for Co. In situ electrical measurements show that Co1–x Fe x (OOH) is conductive under OER conditions (∼0.7–4 mS cm–1 at ∼300 mV overpotential), but that FeOOH is an insulator with measurable conductivity (2.2 × 10–2 mS cm–1) only at high overpotentials >400 mV. The apparent OER activity of FeOOH is thus limited by low conductivity. Microbalance measurements show that films with x ≥ 0.54 (i.e., Fe-rich) dissolve in 1 M KOH electrolyte under OER conditions. For x < 0.54, the films appear chemically stable, but the OER activity decreases by 16–62% over 2 h, likely due to conversion into denser, oxide-like phases. We thus hypothesize that Fe is the most-active site in the catalyst, while CoOOH primarily provides a conductive, high-surface area, chemically stabilizing host. These results are important as Fe-containing Co- and Ni-(oxy)hydroxides are the fastest OER catalysts known.
Using archival Very Long Baseline Interferometry (VLBI) data for 3114 radio-luminous active galactic nuclei, we searched for binary supermassive black holes using a radio spectral index mapping ...technique which targets spatially resolved, double radio-emitting nuclei. Only one source was detected as a double nucleus. This result is compared with a cosmological merger rate model and interpreted in terms of (1) implications for post-merger time-scales for centralization of the two black holes, (2) implications for the possibility of 'stalled' systems and (3) the relationship of radio activity in nuclei to mergers. Our analysis suggests that binary pair evolution of supermassive black holes (both of masses ≥108 M⊙) spends less than 500 Myr in progression from the merging of galactic stellar cores to within the purported stalling radius for supermassive black hole pairs. The data show no evidence for an excess of stalled binary systems at small separations. We see circumstantial evidence that the relative state of radio emission between paired supermassive black holes is correlated within orbital separations of 2.5 kpc.
Fe cations dramatically enhance oxygen evolution reaction (OER) activity when incorporated substitutionally into Ni or Co (oxy)hydroxides, serving as possible OER active sites. Pure Fe ...(oxy)hydroxides, however, are typically thought to be poor OER catalysts and are not well-understood. Here, we report a systematic investigation of Fe (oxy)hydroxide OER catalysis in alkaline media. At low overpotentials of ∼350 mV, the catalyst dissolution rate is low, the activity is dramatically enhanced by an AuO x /Au substrate, and the geometric OER current density is largely independent of mass loading. At higher overpotentials of ∼450 mV, the dissolution rate is high, the activity is largely independent of substrate choice, and the geometric current density depends linearly on loading. These observations, along with previously reported in situ conductivity measurements, suggest a new model for OER catalysis on Fe (oxy)hydroxide. At low overpotentials, only the first monolayer of the electrolyte-permeable Fe (oxy)hydroxide, which is in direct contact with the conductive support, is OER-active due to electrical conductivity limitations. On Au substrates, Fe cations interact with AuO x after redox cycling, leading to enhanced intrinsic activity over FeOOH on Pt substrates. At higher overpotentials, the conductivity of Fe (oxy)hydroxide increases, leading to a larger fraction of the electrolyte-permeable catalyst film participating in catalysis. Comparing the apparent activity of the putative Fe active sites in/on different hosts/surfaces supports a possible connection between OER activity and local structure.
Better understanding of the dynamics of the current U.S. overdose epidemic may aid in the development of more effective prevention and control strategies. We analyzed records of 599,255 deaths from ...1979 through 2016 from the National Vital Statistics System in which accidental drug poisoning was identified as the main cause of death. By examining all available data on accidental poisoning deaths back to 1979 and showing that the overall 38-year curve is exponential, we provide evidence that the current wave of opioid overdose deaths (due to prescription opioids, heroin, and fentanyl) may just be the latest manifestation of a more fundamental longer-term process. The 38+ year smooth exponential curve of total U.S. annual accidental drug poisoning deaths is a composite of multiple distinctive subepidemics of different drugs (primarily prescription opioids, heroin, methadone, synthetic opioids, cocaine, and methamphetamine), each with its own specific demographic and geographic characteristics.
Many public health responses and modeled scenarios for COVID-19 outbreaks caused by SARS-CoV-2 assume that infection results in an immune response that protects individuals from future infections or ...illness for some amount of time. The presence or absence of protective immunity due to infection or vaccination (when available) will affect future transmission and illness severity. Here, we review the scientific literature on antibody immunity to coronaviruses, including SARS-CoV-2 as well as the related SARS-CoV, MERS-CoV and endemic human coronaviruses (HCoVs). We reviewed 2,452 abstracts and identified 491 manuscripts relevant to 5 areas of focus: 1) antibody kinetics, 2) correlates of protection, 3) immunopathogenesis, 4) antigenic diversity and cross-reactivity, and 5) population seroprevalence. While further studies of SARS-CoV-2 are necessary to determine immune responses, evidence from other coronaviruses can provide clues and guide future research.
Mitochondrial DNA (mtDNA) plays a crucial but incompletely understood role in cellular biochemistry and etiology of numerous disease states. Thus, there is an urgent need for targeted probes that can ...dynamically respond to changes to mtDNA such as copy number in live cells, but it is difficult to permeate the mitochondrial membrane of the living cell. Now, a ruthenium(II) light‐switching probe targeted by peptide vectorization selectively to mitochondrial nucleoids is presented. Evidence for DNA binding by the probe in live cells is derived from confocal fluorescence microscopy, resonance Raman, and luminescence lifetime imaging. While viable under imaging conditions, specific staining of mitochondrial DNA permitted efficient and selective photoinduced toxicity on a cell‐by‐cell basis under higher excitation intensities. This powerful combination of imaging and photocytotoxicity is an important step towards realizing phototheranostic application of such RuII probes.
Shining a light on mitochondrial DNA: Peptide vectorization targets a luminescence light‐switching RuII complex to mitochondrial DNA in live cells with high precision. Probe binding was multimodally interrogated by a combination of confocal, Raman, and lifetime imaging. This discrete targeting presents exciting opportunities to exploit the promising phototheranostic capabilities of RuII complexes.
Twelve key events leading up to the emergence of the current pandemic swine-origin influenza A (H1N1) virus are reviewed.
Twelve key events leading up to the emergence of the current pandemic ...swine-origin influenza A (H1N1) virus are reviewed.
On April 17, 2009, officials at the Centers for Disease Control and Prevention (CDC) confirmed two cases of swine influenza in children living in neighboring counties in California.
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Here we take a perspective from systems biology to review the series of evolutionary and epidemiologic events, starting in 1918, that led to the emergence of the current swine-origin influenza A (H1N1) strain (S-OIV), which is widely known as swine flu. This article is one of two historical articles on influenza A (H1N1) viruses in this issue of the
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Our review focuses on the key steps that characterize this viral . . .
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