Abstract
Gamma-ray bursts (GRBs) exhibit a diversity of spectra. Several spectral models (e.g., Band, cutoff power law (CPL), and blackbody) and their hybrid versions (e.g., Band+blackbody) have been ...widely used to fit the observed GRB spectra. Here, we attempt to collect all the bursts detected by Fermi/GBM with known redshifts from 2008 July to 2022 May, having been motivated to (i) provide a parameter catalog independent of the official Fermi/GBM team and (ii) achieve a “clean” model-based GRB spectral energy correlation analysis. A nearly complete GRB sample is created, containing 153 such bursts (136 long GRBs and 17 short GRBs). Using the sample and by performing detailed spectral analysis and model comparisons, we investigate two GRB spectral energy correlations: the correlation of the cosmological rest-frame peak energy (
E
p,
z
) of the
ν
F
ν
prompt emission spectrum with (i) the isotropic-bolometric-equivalent emission energy
E
γ
,iso
(the Amati relation) and (ii) the isotropic-bolometric-equivalent peak luminosity
L
p,iso
(the Yonetoku relation). From a linear regression analysis, a tight correlation between
E
p,
z
and
E
γ
,iso
(and
L
γ
,iso
) is found for both Band-like and CPL-like bursts (except for CPL-like long burst
E
p,
z
–
E
γ
,iso
correlation). More interestingly, CPL-like bursts do not fall on the Band-like burst Amati and Yonetoku correlations, suggesting distinct radiation processes, and pointing to the fact that these spectral energy correlations are tightly reliant on the model-wise properties.
Although ether‐based electrolytes have been extensively applied in anode evaluation of batteries, anodic instability arising from solvent oxidability is always a tremendous obstacle to matching with ...high‐voltage cathodes. Herein, by rational design for solvation configuration, the fully coordinated ether‐based electrolyte with strong resistance against oxidation is reported, which remains anodically stable with high‐voltage Na3V2(PO4)2O2F (NVPF) cathode under 4.5 V (versus Na+/Na) protected by an effective interphase. The assembled graphite//NVPF full cells display superior rate performance and unprecedented cycling stability. Beyond that, the constructed full cells coupling the high‐voltage NVPF cathode with hard carbon anode exhibit outstanding electrochemical performances in terms of high average output voltage up to 3.72 V, long‐term cycle life (such as 95 % capacity retention after 700 cycles) and high energy density (247 Wh kg−1). In short, the optimized ether‐based electrolyte enriches systematic options, the ability to maintain oxidative stability and compatibility with various anodes, exhibiting attractive prospects for application.
By rational design of the solvation configuration, a cation–solvent fully coordinated ether‐based electrolyte with strong oxidation resistance up to 4.5 V (versus Na+/Na) was developed and applied in graphite//NVPF and LHC//NVPF full cells which showed superior rate performance and unprecedented cycling stability.
With increasing trend of internet use in all age groups, whether internet use can prevent frailty in middle-aged and older adults remains unclear. Five cohorts, including Health and Retirement Study ...(HRS), China Health and Retirement Longitudinal Study (CHARLS), the Survey of Health, Ageing and Retirement in Europe (SHARE), English Longitudinal Study of Aging (ELSA), and Mexican Health and Aging Study (MHAS), were used in this study. Internet use, social isolation, and frailty status was assessed using similar questions. The Generalized estimating equations models, random effects meta-analysis, COX regression, and mediation analysis were utilized. In the multicohort study, a total of 155,695 participants were included in main analysis. The proportion of internet use was varied across countries, ranging from 5.56% in China (CHARLS) to 83.46% in Denmark (SHARE). According to the generalized estimating equations models and meta-analysis, internet use was inversely associated with frailty, with the pooled ORs (95%CIs) of 0.72 (0.67,0.79). The COX regression also showed that participants with internet use had a lower risk of frailty incidence. Additionally, the association was partially mediated by social isolation and slightly pronounced in participants aged 65 and over, male, not working for payment, not married or partnered, not smoking, drinking, and not co-residence with children. Our findings highlight the important role of internet use in preventing frailty and recommend more engagements in social communication and activities to avoid social isolation among middle-aged and older adults.
Self‐Powered Nanoscale Photodetectors Tian, Wei; Wang, Yidan; Chen, Liang ...
Small (Weinheim an der Bergstrasse, Germany),
12/2017, Letnik:
13, Številka:
45
Journal Article
Recenzirano
Odprti dostop
Novel self‐powered nanoscale photodetectors that can work without an external power source, which have great application potential in next‐generation nanodevices that operate wirelessly and ...independently, are being widely studied. This review aims to give a comprehensive summary of the state‐of‐the‐art research results on self‐powered nanoscale photodetectors. An introduction of recent progress on Schottky junction photodetectors is provided. Two types of Schottky junctions are discussed in detail: metal–semiconductor and semiconductor–graphene junctions. Next, recent developments of p–n junction photodetectors are highlighted, including homojunction and heterojunction photodetectors. Then, piezo‐phototronic effect enhanced photodetection performances of Schottky junctions and p–n junctions are discussed. Then, significant results on the photoelectrochemical‐cell‐based photodetector and integrated self‐powered nanosystem are presented, followed by a systematic comparison of different types of photodetectors. Finally, a summary of the previous results is given, and the major challenges that need to be addressed in the future are outlined. The hope is that this review can provide valuable insights into the current status of self‐powered photodetectors and spur new structure and device designs to further enhance photodetection performance.
Self‐powered nanoscale photodetectors that work without an external power source and meet the demands of small size, low weight, and low power consumption are being widely studied for next generation nanodevices. Here, a comprehensive summary is given of the state‐of‐the‐art results on self‐powered nanoscale photodetectors, including those based on the Schottky junction, p–n junction, photoelectrochemical cell, and integrated nanosystem.
Many COVID-19 patients infected by SARS-CoV-2 virus develop pneumonia (called novel coronavirus pneumonia, NCP) and rapidly progress to respiratory failure. However, rapid diagnosis and ...identification of high-risk patients for early intervention are challenging. Using a large computed tomography (CT) database from 3,777 patients, we developed an AI system that can diagnose NCP and differentiate it from other common pneumonia and normal controls. The AI system can assist radiologists and physicians in performing a quick diagnosis especially when the health system is overloaded. Significantly, our AI system identified important clinical markers that correlated with the NCP lesion properties. Together with the clinical data, our AI system was able to provide accurate clinical prognosis that can aid clinicians to consider appropriate early clinical management and allocate resources appropriately. We have made this AI system available globally to assist the clinicians to combat COVID-19.
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•AI system that can diagnose COVID-19 pneumonia using CT scans•Prediction of progression to critical illness•Potential to improve performance of junior radiologists to the senior level•Can assist evaluation of drug treatment effects with CT quantification
Zhang et al. present an AI-based system, based on hundreds of thousands of human lung CT scan images, that can aid in distinguishing patients NCP versus other common pneumonia and can help to predict the prognosis of COVID-19 patients.
Evapotranspiration (ET) is one of the key variables in the water and energy exchange between land surface and atmosphere. This paper develops an end-member-based two-source approach for estimating ...land surface ET (i.e., the ESVEP model) from remote sensing data, considering the differing responses of soil water content at the upper surface layer to soil evaporation and at the deeper root zone layer to vegetation transpiration. The ESVEP model first diverges the soil-vegetation system net radiation into soil and vegetation components by considering the transmission of direct and diffuse shortwave radiation separately from the transmission of longwave radiation through the canopy, then calculates the four dry/wet soil/vegetation end-members with the diverged soil and vegetation net radiations, and last separates soil evaporation from vegetation transpiration based on the two-phase ET dynamics and the four end-member temperatures. The model can overall produce reasonably good surface energy fluxes and is no more sensitive to meteorology, vegetation, and remote sensing inputs than other two-source energy balance models and surface temperature versus vegetation index (T_{R} -VI) trapezoid models. A reasonable agreement could be found with a small bias of ±8 W/\text{m}^{2} and a root-mean-square error within 60 W/\text{m}^{2} (comparable to accuracies published in other studies) when both model-estimated sensible heat flux and latent heat flux from MODIS remote sensing data are validated with ground-based large aperture scintillometer measurements.
•Sample-to-sample amount variation could be larger than analytical variation.•Sample normalization is a critical step in quantitative metabolomics.•Sample normalization should be incorporated into a ...metabolomic profiling workflow.•There is no unified method but a number of methods have been reported.•The performance of sample normalization methods needs to be carefully considered to select a proper method.
To reveal metabolomic changes caused by a biological event in quantitative metabolomics, it is critical to use an analytical tool that can perform accurate and precise quantification to examine the true concentration differences of individual metabolites found in different samples. A number of steps are involved in metabolomic analysis including pre-analytical work (e.g., sample collection and storage), analytical work (e.g., sample analysis) and data analysis (e.g., feature extraction and quantification). Each one of them can influence the quantitative results significantly and thus should be performed with great care. Among them, the total sample amount or concentration of metabolites can be significantly different from one sample to another. Thus, it is critical to reduce or eliminate the effect of total sample amount variation on quantification of individual metabolites. In this review, we describe the importance of sample normalization in the analytical workflow with a focus on mass spectrometry (MS)-based platforms, discuss a number of methods recently reported in the literature and comment on their applicability in real world metabolomics applications. Sample normalization has been sometimes ignored in metabolomics, partially due to the lack of a convenient means of performing sample normalization. We show that several methods are now available and sample normalization should be performed in quantitative metabolomics where the analyzed samples have significant variations in total sample amounts.
A biomimetic (titin protein molecular structure) strategy is reported for preparing transparent and healable elastomers featuring supertoughness (345 MJ m−3) and high tensile strength (44 MPa) after ...self‐healing enabled by hierarchical (single, double, and quadruple) hydrogen‐bonding moieties in the polymer backbone. The rigid domain containing hierarchical H‐bonds formed with urethane, urea, and 2‐ureido‐41H‐pyrimidinone groups leads to a durable network structure that has enhanced mechanical properties and is also dynamic for rapid self‐healing. Healable polymers with hierarchical hydrogen‐bonding interactions show excellent recoverability and high energy dissipation owing to the durable interaction between polymer chains. This biomimetic strategy of using hierarchical hydrogen bonds as building blocks is an alternative approach for obtaining dynamic, strong, yet smart self‐healing polymers for heavy‐duty protection materials and wearable electronics.
Supertough self‐healing elastomers were constructed by a biomimetic synthetic strategy and control of the nanophase structure with hierarchical (single, double, quadruple) hydrogen‐bonding motifs. The successive dynamic interaction of the H‐bonds and increased chain mobility contribute to the self‐healing and supertough mechanical properties. The toughness after self‐healing reached 345 MJ m−3.
Key points
In a cold environment, mammals increase their food intake while fish decrease or stop feeding. However, the physiological value of fasting during cold resistance in fish is currently ...unknown.
Fasting for more than 48 h enhanced acute cold resistance in zebrafish, which correlated with lipid catabolism and cell damage attenuation.
Lipid catabolism and autophagy were necessary for cold resistance in fish and the inhibition of mitochondrial fatty acid β‐oxidation or autophagy weakened the fasting‐induced cold resistance.
Repression of mechanistic target of rapamycin (mTOR) signalling pathway by rapamycin largely mimicked the beneficial effects of fasting in promoting cold resistance, suggesting mTOR signalling may be involved in the fasting‐induced cold resistance in fish.
Our study demonstrates that fasting may be a protective strategy for fish to survive under cold stress.
In cold environments, most homeothermic animals increase their food intake to supply more energy to maintain body temperature, whereas most poikilothermic animals such as fishes decrease or even stop feeding under cold stress. However, the physiological value of fasting during cold resistance in poikilotherms has not been explained. Here, we show that moderate fasting largely enhanced cold resistance in fish. By using pharmacological (fenofibrate, mildronate, chloroquine and rapamycin) and nutritional approaches (fatty acids diets and amino acids diets) in wild‐type or specific gene knock‐out zebrafish models (carnitine palmitoyltransferase‐1b‐deficient strain, CPT1b−/−, or autophagy‐related protein 12‐deficient strain, ATG12−/−), we verified that fasting‐stimulated lipid catabolism and autophagy played essential roles in the improved cold resistance. Moreover, suppression of the mechanistic target of rapamycin (mTOR) pathway by using rapamycin mostly mimicked the beneficial effects of fasting in promoting cold resistance as either the physiological phenotype or transcriptomic pattern. However, these beneficial effects were largely reduced when the mTOR pathway was activated through high dietary leucine supplementation. We conclude that fasting helps fish to resist cold stress by modulating lipid catabolism and autophagy, which correlates with the mTOR signalling pathway. Therefore, fasting can act as a protective strategy of fish in resisting coldness.
Key points
In a cold environment, mammals increase their food intake while fish decrease or stop feeding. However, the physiological value of fasting during cold resistance in fish is currently unknown.
Fasting for more than 48 h enhanced acute cold resistance in zebrafish, which correlated with lipid catabolism and cell damage attenuation.
Lipid catabolism and autophagy were necessary for cold resistance in fish and the inhibition of mitochondrial fatty acid β‐oxidation or autophagy weakened the fasting‐induced cold resistance.
Repression of mechanistic target of rapamycin (mTOR) signalling pathway by rapamycin largely mimicked the beneficial effects of fasting in promoting cold resistance, suggesting mTOR signalling may be involved in the fasting‐induced cold resistance in fish.
Our study demonstrates that fasting may be a protective strategy for fish to survive under cold stress.
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