Development of efficient and durable oxygen evolution reaction (OER) catalysts has a direct impact on the water splitting efficiency and cost effectiveness. In this work, we report the successful ...synthesis of a new Ni(OH)
2
structure, strain-stabilized Ni(OH)
2
nanoribbons (NR-Ni(OH)
2
) two to three layers thick, with widths of 2-5 nm,
via
an electro-oxidation route. Conventional Ni(OH)
2
usually has negligible OER activity, while NR-Ni(OH)
2
shows high activity for the oxygen evolution reaction and an overpotential of 162 millivolts and furthermore exhibits long-term stability in alkaline electrolyte. The substantial reduction in the overpotential of NR-Ni(OH)
2
is due to its easier OOH* adsorption by the active four-coordinated Ni edge sites. The enhanced catalytic activity of NR-Ni(OH)
2
makes it an excellent candidate for industrial applications.
Development of efficient and durable oxygen evolution reaction (OER) catalysts has a direct impact on the water splitting efficiency and cost effectiveness.
High-energy photons from the Crab Nebula
The Crab Nebula contains a pulsar that excites the surrounding gas to emit high-energy radiation. The combination of the pulsar's youth and nearby location ...makes the nebula the brightest gamma-ray source in the sky. The LHAASO Collaboration report observations of this source at energies of tera– to peta–electron volts, extending the spectrum of this prototypical object. They combine these data with observations at lower energies to model the physics of the emission process. The multiwave-length data can be explained by a combination of synchrotron radiation and inverse Compton scattering.
Science
, abg5137, this issue p.
425
Detection of the Crab Nebula at peta–electron volt energies constrains the gamma-ray emission mechanism.
The Crab Nebula is a bright source of gamma rays powered by the Crab Pulsar’s rotational energy through the formation and termination of a relativistic electron-positron wind. We report the detection of gamma rays from this source with energies from 5 × 10
−4
to 1.1 peta–electron volts with a spectrum showing gradual steepening over three energy decades. The ultrahigh-energy photons imply the presence of a peta–electron volt electron accelerator (a pevatron) in the nebula, with an acceleration rate exceeding 15% of the theoretical limit. We constrain the pevatron’s size between 0.025 and 0.1 parsecs and the magnetic field to ≈110 microgauss. The production rate of peta–electron volt electrons, 2.5 × 10
36
ergs per second, constitutes 0.5% of the pulsar spin-down luminosity, although we cannot exclude a contribution of peta–electron volt protons to the production of the highest-energy gamma rays.
Background
Acupuncture is used to treat chronic functional constipation (CFC) in China, despite limited evidence. We aim to assess the effectiveness and safety of acupuncture in managing CFC.
Methods
...A multicenter randomized controlled trial was performed involving 684 patients with CFC; the patients were randomly allocated to receive He acupuncture (n = 172), Shu‐mu acupuncture (n = 171), He‐shu‐mu acupuncture (n = 171), or oral administration of mosapride (n = 170). Sixteen sessions of acupuncture were given in the treatment duration of 4 weeks. The primary outcome was the change in spontaneous bowel movements (SBMs) at week 4 (at the end of treatment) compared to baseline. The secondary outcomes included stool consistency (Bristol scale), the degree of straining during defecation, and adverse events.
Key Results
The SBMs increased in all the four groups at week 4, and the magnitude of increase was equivalent in the four groups (He acupuncture, 2.7 95% CI, 2.3‐3.1; Shu‐mu acupuncture, 2.7 95% CI, 2.3‐3.0; He‐shu‐mu acupuncture, 2.2 95% CI, 1.9‐2.5; and mosapride, 2.4 95% CI, 2.0‐2.9; P = .226). However, the change in SBMs at week 8 was significantly smaller in mosapride group (1.4 95% CI, 1.0‐1.8) than the three acupuncture groups (2.4 95% CI, 2.1‐2.7, 2.3 95% CI, 1.9‐2.7, 2.1 95% CI, 1.7‐2.5 in He, Shu‐mu, and He‐shu‐mu group, respectively, P = .005).
Conclusions & Interferences
The three acupuncture treatments were as effective as mosapride in improving stool frequency and stool consistency in CFC, but the magnitude of the treatment effect is unknown due to the lack of sham acupuncture control.
The effectiveness of acupuncture in the treatment of chronic functional constipation is unknown. Our study result showed that acupuncture treatments are as effective as mosapride in improving stool frequency and stool consistency.
Typical high-efficiency organic light-emitting diodes (OLEDs) require exotic high-refractive-index (n ≥ 1.8) substrates to enhance the outcoupling of trapped light in the device. One of the exciting ...possibilities of OLEDs is the use of lightweight flexible plastic substrates, which unfortunately have a low refractive index (n ≤ 1.6). To unlock the full potential of OLEDs on flexible plastic, we report high-efficiency phosphorescent OLEDs using a thin-film outcoupling enhancement method that does not depend on high-index substrates. In these devices, multifunctional anode stacks, consisting of a high-index Ta2 O5 optical coupling layer, electrically conductive gold layer and hole-injection MoO3 layer, are collectively optimized to achieve high efficiency. The maximum external quantum efficiency reaches 63% for green, which remains as high as 60% at >10,000 cd m-2 .
The electron rolling‐pin distribution, showing electron pitch angles primarily at 0°, 90°, and 180°, has been widely studied in the Earth's magnetosphere, but has never been reported in other ...planetary environments. Here, by utilizing the Jupiter Near‐polar Orbiter (Juno) measurements, we report for the first time the electron rolling‐pin distribution in Jupiter's magnetosphere. We reveal the energy range of such distribution and find it appears only above 19.5 keV, falling well into the suprathermal energy range. Moreover, we quantitively reproduce the formation processes of such distribution by using an analytical model. Gratifyingly, the distribution derived from the analytical model agrees well with the Juno observations, indicating such distribution is formed by the combination of global‐scale Fermi acceleration and local‐scale betatron acceleration. These results, demonstrating that the electron rolling‐pin distribution exists beyond the Earth, can improve our knowledge of electron dynamics in planetary magnetosphere.
Plain Language Summary
Examining the electron pitch angle distribution can help us better understand the electron dynamics in planetary magnetosphere. Up to now, it still remains unknown whether the rolling‐pin distribution, which shows pitch angles primarily at 0°, 90°, and 180°, exists beyond the Earth. Here using the Juno measurements, for the first time, we report such distribution in the Jupiter's magnetosphere. We find the rolling‐pin distribution appears only in the suprathermal electrons, and further explain its formation processes by using an analytical model. Our study is useful to understand electron dynamics in planetary magnetosphere.
Key Points
We for the first time provide the evidence of electron rolling‐pin distribution in Jupiter's magnetosphere
The rolling‐pin distribution appears only above 19.5 keV, falling well into the suprathermal energy range
The rolling‐pin distribution is formed by the combination of global‐scale Fermi acceleration and local‐scale betatron acceleration
Recently, the LHAASO Collaboration published the detection of 12 ultrahigh-energy γ-ray sources above 100 TeV, with the highest energy photon reaching 1.4 PeV. The first detection of PeV γ rays from ...astrophysical sources may provide a very sensitive probe of the effect of the Lorentz invariance violation (LIV), which results in decay of high-energy γ rays in the superluminal scenario and hence a sharp cutoff of the energy spectrum. Two highest energy sources are studied in this work. No signature of the existence of the LIV is found in their energy spectra, and the lower limits on the LIV energy scale are derived. Our results show that the first-order LIV energy scale should be higher than about 10^{5} times the Planck scale M_{Pl} and that the second-order LIV scale is >10^{-3}M_{Pl}. Both limits improve by at least one order of magnitude the previous results.
Full text
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In organic light-emitting diodes (OLEDs), a stack of multiple organic layers facilitates charge flow from the low work function ~4.7 electron volts (eV) of the transparent electrode (tin-doped indium ...oxide, ITO) to the deep energy levels (~6 eV) of the active light-emitting organic materials. We demonstrate a chlorinated ITO transparent electrode with a work function of >6.1 eV that provides a direct match to the energy levels of the active light-emitting materials in state-of-the art OLEDs. A highly simplified green OLED with a maximum external quantum efficiency (EQE) of 54% and power efficiency of 230 lumens per watt using outcoupling enhancement was demonstrated, as were EQE of 50% and power efficiency of 110 lumens per watt at 10,000 candelas per square meter.
The kilometer square array (KM2A) of the large high altitude air shower observatory (LHAASO) aims at surveying the northern γ-ray sky at energies above 10 TeV with unprecedented sensitivity. γ-ray ...observations have long been one of the most powerful tools for dark matter searches, as, e.g., high-energy γ rays could be produced by the decays of heavy dark matter particles. In this Letter, we present the first dark matter analysis with LHAASO-KM2A, using the first 340 days of data from 1/2-KM2A and 230 days of data from 3/4-KM2A. Several regions of interest are used to search for a signal and account for the residual cosmic-ray background after γ/hadron separation. We find no excess of dark matter signals, and thus place some of the strongest γ-ray constraints on the lifetime of heavy dark matter particles with mass between 10^{5} and 10^{9} GeV. Our results with LHAASO are robust, and have important implications for dark matter interpretations of the diffuse astrophysical high-energy neutrino emission.
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Previous studies of geometric and morphologic parameters of intracranial aneurysms have been conducted to determine rupture risk, which remains incompletely defined due to patient-specific risk ...factors, such as sex, hypertension, and age. To this end, we compared characteristics of ruptured and unruptured aneurysms in the same patients with symmetric bilateral intracranial aneurysms.
Between January 2008 and March 2014, 2361 patients with 2674 aneurysms were diagnosed by CT angiography or surgical findings at 4 medical centers. Geometric and morphologic parameters examined for symmetric bilateral intracranial aneurysms comprised aneurysm wall regularity, size, neck width, aspect ratio, size ratio, neck-to-parent artery ratio, and area ratio. Univariate and multivariate statistical analyses were performed to determine independent risk factors for rupture.
Sixty-three patients (48 women, 15 men; mean age, 62.5 ± 9.8 years) with symmetric bilateral aneurysms were eligible for the study and were included. The most frequent aneurysm location was the posterior communicating artery. Univariate analysis disclosed that aneurysm size, aspect ratio, size ratio, area ratio, and irregular wall differed between patients with ruptured and unruptured aneurysms. Multivariate analysis indicated that aspect ratio of ≥1.6 (adjusted OR, 9.521; 95% CI, 2.182-41.535), area ratio of ≥1.5 (adjusted OR, 4.089; 95% CI, 1.247-13.406), and irregular shape (adjusted OR, 10.443; 95% CI 3.394-32.135) were significant predictive factors for aneurysm rupture after adjustment for aneurysm size.
An aspect ratio of ≥1.6, area ratio of ≥1.5, and irregular wall are associated with aneurysm rupture independent of aneurysm size and patient characteristics. These characteristics alone can help in distinguishing ruptured bilateral intracranial aneurysms from unruptured ones.
Abstract
We report the discovery of an ultrahigh-energy (UHE) gamma-ray source, LHAASO J2108+5157, by analyzing the LHAASO-KM2A data of 308.33 live days. A significant excess of gamma ray–induced ...showers is observed in both energy bands of 25−100 and >100 TeV with 9.5
σ
and 8.5
σ
, respectively. This source is not significantly favored as an extended source with an angular extension smaller than the point-spread function of KM2A. The measured energy spectrum from 20 to 200 TeV can be approximately described by a power-law function with an index of −2.83 ± 0.18
stat
. A harder spectrum is demanded at lower energies considering the flux upper limit set by Fermi-LAT observations. The position of the gamma-ray emission is correlated with a giant molecular cloud, which favors a hadronic origin. No obvious counterparts have been found, and deeper multiwavelength observations will help to cast new light on this intriguing UHE source.
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