Zn–air batteries are becoming the promising power sources for portable and wearable electronic devices and hybrid/electric vehicles because of their high specific energy density and the low cost for ...next‐generation green and sustainable energy technologies. An air electrode integrated with an oxygen electrocatalyst is the most important component and inevitably determines the performance and cost of a Zn–air battery. This article presents exciting advances and challenges related to air electrodes and their relatives. After a brief introduction of the Zn–air battery, the architectures and oxygen electrocatalysts of air electrodes and relevant electrolytes are highlighted in primary and rechargeable types with different configurations, respectively. Moreover, the individual components and major issues of flexible Zn–air batteries are also highlighted, along with the strategies to enhance the battery performance. Finally, a perspective for design, preparation, and assembly of air electrodes is proposed for the future innovations of Zn–air batteries with high performance.
Air electrodes integrated with oxygen electrocatalysts are the most important component of Zn–air batteries. Advances in air electrodes and related components for Zn–air batteries are reviewed, providing valuable insights to promote innovation and commercialization of Zn–air batteries.
Computed tomography (CT) is the preferred imaging method for diagnosing 2019 novel coronavirus (COVID19) pneumonia. We aimed to construct a system based on deep learning for detecting COVID-19 ...pneumonia on high resolution CT. For model development and validation, 46,096 anonymous images from 106 admitted patients, including 51 patients of laboratory confirmed COVID-19 pneumonia and 55 control patients of other diseases in Renmin Hospital of Wuhan University were retrospectively collected. Twenty-seven prospective consecutive patients in Renmin Hospital of Wuhan University were collected to evaluate the efficiency of radiologists against 2019-CoV pneumonia with that of the model. An external test was conducted in Qianjiang Central Hospital to estimate the system's robustness. The model achieved a per-patient accuracy of 95.24% and a per-image accuracy of 98.85% in internal retrospective dataset. For 27 internal prospective patients, the system achieved a comparable performance to that of expert radiologist. In external dataset, it achieved an accuracy of 96%. With the assistance of the model, the reading time of radiologists was greatly decreased by 65%. The deep learning model showed a comparable performance with expert radiologist, and greatly improved the efficiency of radiologists in clinical practice.
Microarc oxidation (MAO) is a common surface treatment technology for Mg alloys. The MAO layer, however, often fails to provide long-term protection due to its inherent porosity. Current interests ...are mostly focused on strengthening the corrosion resistance by combining MAO with other film techniques. In this work, we developed a smart protective system characteristic of superhydrophobicity and active self-healing capability on Mg alloy by integrating MAO and electro-assisted sol–gel deposition. The porous MAO precoating could work as both a “shield” and a “reservoir”, respectively, to gain enhanced impedance and sufficient inhibitor loading. The top silica skeletons were responsible for surface superhydrophobicity, used for blocking electrolyte invasion and avoiding premature inhibitor leaching. Using this new system, a highly enhanced corrosion barrier relative to pristine MAO or single superhydrophobic surface was acquired. Furthermore, the self-healing effect of embedded inhibitor was underpinned by in situ scanning vibrating electrode technology. It is expected that the MAO-based duplex coating would further boost the development of functional surfaces for Mg alloy protection.
•Non-uniform electric field results in the variation of Cu2+/Cu+ ratio.•A two-layered structure was formed in the black area.•Both Cu species and Ca, P-rich compounds are crucial for biological ...performance.
In the present work, a Cu-incorporated TiO2 coating was successfully fabricated through a one-step micro-arc oxidation (MAO) of Ti in a solution containing 10 g/L ethylene diamine tetraacetic acid cupric disodium (Na2Cu-EDTA). Interestingly, different colour appearances of the resultant Cu-incorporated TiO2 coating were noticed with the presence of black area at the edge and brown area in the centre. Further, microstructural characterization reveals that, unlike the central brown area with high amount of Cu+, the peripheral black area is mainly enriched in Cu2+, which exhibits a two-layered structure consisting of TiO2 inner layer and porous Ca, P-rich outer layer containing nano-sized hydroxyapatite (HA) crystals. Finally, biological examination reveals that the peripheral black area exhibits both improved bone formability and enhanced antibacterial capability in comparison to the central brown area. Based on the observation, the coating formation mechanism is proposed, which provides valuable guidance for the utilization of MAO method in the field of bio-medical materials.
On 3 January 2019, the Chang'e‐4 (CE‐4) touched down on the Von Karman crater located inside the South Pole‐Aitken Basin, providing for the first time the opportunity for in situ measurements of the ...lunar regolith at the farside of the Moon. The CE‐4 ground penetrating radar reveals that fine‐grained regolith, coarse impact ejecta, and fractured bedrocks lie beneath the exploration path of the Yutu‐2 rover. The variations of regolith permittivity with depth and the radargrams indicate that the CE‐4 site has a fine‐grained regolith layer thickness of 11.1 m, which is about 1.3–3 times higher than the in situ measurement results at the Apollo and Chang'e‐3 (CE‐3) sites except for Apollo 16, possibly due to a faster weathering rate of ejecta deposits compared with coherent basalt substrates. The penetration depth of CE‐4 is about 2.85 times (in terms of round‐way delay) deeper than CE‐3, probably due to the differences in abundances of ilmenite and rocks in the regolith.
Plain Language Summary
CE‐4 is the first craft in history to land on the lunar farside. Its rover is equipped with a ground‐penetrating radar (GPR), the same as the one mounted on the CE‐3 rover, which uses pulses of electromagnetic energy to reveal the subsurface structure and properties, especially useful to study the lunar soil layer (“regolith”) that mantles most of the lunar surface. The results from the GPR show that the thickness of the regolith at the CE‐4 site is 1.3–3 times higher than the in situ measurements at the Apollo 11,12,14,15, 17, and CE‐3 sites even though the ages of the surfaces of Apollo 11 and Apollo 17 are thought to be comparable with that of the CE‐4 site. It implies a faster regolith growth speed at the CE‐4 site. The mineral mix of the surface materials at the CE‐4 site is different from that at the CE‐3: this results in less radar signal attenuation, thus increasing the detection limit up to the depth of 35 m, 2.85 times deeper than the CE‐3.
Key Points
The LPR measurements at the CE‐4 landing site reveal that the shallow structure comprises of fine‐grained regolith, coarse impact ejecta, and fractured bedrocks
The CE‐4 landing site has a thicker regolith layer (~11 m) compared with the CE‐3, hinting at a longer weathering history
A lower abundance of ilmenite and rocks in the regolith at the CE‐4 site allows 2.85 times the penetration depth compared with CE‐3 site
Stereo matching in binocular endoscopic scenarios is difficult due to the radiometric distortion caused by restricted light conditions. Traditional matching algorithms suffer from poor performance in ...challenging areas, while deep learning ones are limited by their generalizability and complexity. We introduce a non-deep learning cost volume generation method whose performance is close to a deep learning algorithm, but with far less computation. To deal with the radiometric distortion problem, the initial cost volume is constructed using two radiometric invariant cost metrics, the histogram of gradient angle and amplitude descriptors. Then we propose a new cross-scale propagation framework to improve the matching reliability in small homogenous regions without increasing the running time. The experimental results on the Middlebury Version 3 Benchmark show that the performance of the combination of our method and Local-Expansion, an optimization algorithm, ranks top among non-deep learning algorithms. Other quantitative experimental results on a surgical endoscopic dataset and our binocular endoscope show that the accuracy of the proposed algorithm is at the millimeter level which is comparable to the accuracy of deep learning algorithms. In addition, our method is 65 times faster than its deep learning counterpart in terms of cost volume generation.
On January 3, 2019, Chang'E-4 (CE-4) probe successfully achieved soft landing on the farside of the Moon. A large number of small craters in the landing area can be found in the high-resolution ...remote sensing images. These small craters played a vital role in the evolution of lunar regolith because of the overturning and mixing of lunar surface material through excavating and ejecting during impact processes. However, the research of the gardening process by small craters and the evolution of farside lunar regolith are still insufficient. This research aims to make quantitative analysis to the evolution of the lunar regolith from regional small impacts and apply them in the CE-4 landing area. Firstly, the processes of excavation and ejection of a single small impact on the lunar surface are analyzed, during which the formation and distribution of lunar regolith are numerically modeled. Then, based on the remote sensing observation and the analysis of regional impact flux, a group of impact events with resulting lunar regolith are modeled by Monte Carlo method. Thirdly, the above analysis is applied in the CE-4 landing area, and the thickness, grain size distribution, and overturning times of the lunar regolith are calculated. Finally, the influencing factors are discussed and evolution process of lunar regolith is summarized. The results indicate that the formation of lunar regolith is controlled by larger impact events, while the surficial overturning and mixing of lunar regolith are mainly caused by smaller impact events. In addition, the lunar regolith is mostly formed in the earlier times because of the high impact flux at that time. For example, the absolute model age of the CE-4 landing area is about 3.5 Ga, while the lunar regolith had mostly been formed before 3.0 Ga and changed slowly afterwards. Our model beyond the observational capability of the Yutu-2's lunar penetrating radar (LPR), and the results can contribute to better understanding of the regional lunar regolith formation and evolution.
•Lunar regolith evolution is quantitatively analyzed with the proposed EMSC.•Lunar regolith formation is mostly controlled by larger impact events.•Lunar regolith in CE-4 landing area is mainly formed before 3.0 Ga.
Designing earth-abundant electrocatalysts with high performance towards water oxidation is highly decisive for the sustainable energy technologies. This study develops a facile natural corrosion ...approach to fabricate nickel-iron hydroxides for water oxidation. The resulted electrode demonstrates an outstanding activity and stability with an overpotential of 275 mV to deliver 10 mA·cm
−2
. Experimental and theoretical results suggest the corrosion-induced formation of hydroxides and their transformation to oxyhydroxides would account for this excellent performance. This work not only provides an interesting corrosion approach for the fabrication of excellent water oxidation electrode, but also bridges traditional corrosion engineering and novel materials fabrication, which would offer some insights in the innovative principles for nanomaterials and energy technologies.
Fenofibrate is a marketed fibric acid derivative for lipid-lowering in patients with lipid disorders. Numerous studies have proven fenofibrate had a certain effect on serum uric acid, here we ...conducted this study to quantitatively assess the effect of fenofibrate intervention in modulating serum uric acid concentration and the influence on serum creatinine. The PubMed, Embase and Cochrane were systematically searched for randomized controlled trials update to January, 2020. Primary endpoints focused on serum uric acid concentration and serum creatinine concentration. The pooled effects were calculated as weighted mean difference (WMD) by a random-effects model. Finally, 9 studies representing 487 patients were included in the meta-analysis. The meta-analysis demonstrated that fenofibrate significantly reduced serum uric acid levels (WMD –1.32 mg/dL, 95%CI –1.61 to –1.03, p < 0.001) and an elevated level in serum creatinine (WMD 0.09 mg/dL, 95%CI 0.02 to 0.15, p < 0.001) following fenofibrate therapy compared with placebo. The present study provided strong evidence that fenofibrate intervention exerted a significant reduction on serum uric acid and a mild increase on serum creatinine. Meta-analysis suggested that there were no significant association between the serum uric acid lowering effect with either dose or treatment duration. Overall, our meta-analysis ascertained that fenofibrate have potential therapeutic effects in patients with lipid metabolic abnormalities but with mid nephrotoxicity. There is strong evidence to provide future direction of practical application and clinical researches of fenofibrate.
Recently, Wi-Fi channel state information (CSI) motion detection systems have been widely researched for applications in human health care and security in flat floor environments. However, these ...systems disregard the indoor context, which is often complex and consists of unique features, such as staircases. Motion detection on a staircase is also meaningful and important for various applications, such as fall detection and intruder detection. In this paper, we present the difference in CSI motion detection in flat floor and staircase environments through analysing the radio propagation model and experiments in real settings. For comparison in the two environments, an indoor CSI motion detection system is proposed with several novel methods including correlation-based fusion, moving variance segmentation (MVS), Doppler spread spectrum to improve the system performance, and a correlation check to reduce the implementation cost. Compared with existing systems, our system is validated to have a better performance in both flat floor and staircase environments, and further utilized to verify the superior CSI motion detection performance in staircase environments versus flat floor environments.
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