Abstract
Although the interactions between soil moisture (SM) and vegetation dynamics have been extensively investigated, most of previous findings are derived from satellite-observed and/or ...model-simulated SM data, which inevitably include multiple sources of error. With the effort of many field workers and researchers in
in-situ
SM measurement and SM data integration, it is now possible to obtain the integrated
in-situ
SM dataset in the global range. Here we used the
in-situ
SM dataset of the International Soil Moisture Network to analyze the anomaly correlation between SM and leaf area index (LAI). We found that positive (negative) correlations exist between SM (LAI) and temporally lagged LAI (SM). The peak correlation and lagging time to reach it (often less than 3 months) depends on climate, land cover and rooting depths. The high SM-LAI anomaly correlation prevails in water-limited regions, e.g. dryland, where plant physiology has strong sensitivity to subsurface water stress. Dynamics of vegetation with deeper maximum rooting depths are not always correlated with SM in deeper soil layers, and vegetation dynamics with shallower maximum rooting depth may strongly correlate with SM in deeper soil layers. Overall, we highlight the potential of the global
in-situ
SM observation network to analyze the interactions between SM and vegetation dynamics.
Abstract
Potassium metal is an appealing alternative to lithium as an alkali metal anode for future electrochemical energy storage systems. However, the use of potassium metal is hindered by the ...growth of unfavourable deposition (e.g., dendrites) and volume changes upon cycling. To circumvent these issues, we propose the synthesis and application of nitrogen and zinc codoped porous carbon nanofibres that act as potassium metal hosts. This carbonaceous porous material enables rapid potassium infusion (e.g., < 1 s cm
−2
) with a high potassium content (e.g., 97 wt. %) and low potassium nucleation overpotential (e.g., 15 mV at 0.5 mA cm
−2
). Experimental and theoretical measurements and analyses demonstrate that the carbon nanofibres induce uniform potassium deposition within its porous network and facilitate a dendrite-free morphology during asymmetric and symmetric cell cycling. Interestingly, when the potassium-infused carbon material is tested as an active negative electrode material in combination with a sulfur-based positive electrode and a nonaqueous electrolyte solution in the coin cell configuration, an average discharge voltage of approximately 1.6 V and a discharge capacity of approximately 470 mA h g
−1
after 600 cycles at 500 mA g
−1
and 25 °C are achieved.
Hydroxyl radicals are often called the "detergent" of the atmosphere because they control the atmosphere's capacity to cleanse itself of pollutants. Here, we show that the reaction of electronically ...excited nitrogen dioxide with water can be an important source of tropospheric hydroxyl radicals. Using measured rate data, along with available solar flux and atmospheric mixing ratios, we demonstrate that the tropospheric hydroxyl contribution from this source can be a substantial fraction (50%) of that from the traditional O(¹D) + H₂O reaction in the boundary-layer region for high solar zenith angles. Inclusion of this chemistry is expected to affect modeling of urban air quality, where the interactions of sunlight with emitted NOx species, volatile organic compounds, and hydroxyl radicals are central in determining the rate of ozone formation.
Full text
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Considering its high theoretical energy density and high safety, the all-solid-state lithium-sulfur battery (ASSLSB) has become a promising candidate for the next-generation energy storage system. ...However, the low reactivity of sulfur and high interfacial resistances between the cathodes and solid electrolytes seriously hinder the practical application of high performance ASSLSBs. Sulfurized polyacrylonitrile (S@pPAN), which can effectively alleviate the volume expansion of sulfur, is a suitable choice for the sulfur cathode, but shows limited performance in ASSLSB. Here, we demonstrate a tellurium-doped S@pPAN (Te0.05S0.95@pPAN) cathode coated with solid electrolyte (Li7P3S11) for an ASSLSB with high reactivity and significant cycling stability. Benefiting from the thin layer coating of Li7P3S11 and the effect of Te-doping, the Te0.05S0.95@pPAN@Li7P3S11 composite delivers significantly enhanced reaction kinetics and excellent interfacial compatibility with the solid electrolyte. At room temperature, the assembled ASSLSB exhibits excellent rate and long cycling performance, with a reversible capacity over 1173.1 mAh g−1 and stable cycling over 500 cycles. The strategy of Te-doping and surface coating not only is facile and promising, but also provides guidance for constructing applicable ASSLSBs.
A facile strategy involving Te-doping and surface coating is demonstrated in modifying sulfurized polyacrylonitrile (S@pPAN) cathode for all-solid-state lithium-sulfur battery (ASSLSB). Benefiting from the thin layer coating of Li7P3S11 and the effect of Te-doping, the Te0.05S0.95@pPAN@Li7P3S11 composite exhibits elevated reactivity and cycling stability, resulting in a high performance ASSLSB. Display omitted
●A facile strategy using Te-doping and surface coating is shown to modify the cathode for a high performance all-solid-state lithium-sulfur battery.●Through an in situ liquid-phase approach, a thin solid electrolyte (Li7P3S11) is coated on the surface of Te-doped sulfurized polyacrylonitrile.●The combination of Te-doping and surface coating leads to enhanced reactivity and cycling stability in the all-solid-state battery.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Predicting students’ performance is very important in matters related to higher education as well as with regard to deep learning and its relationship to educational data. Prediction of students’ ...performance provides support in selecting courses and designing appropriate future study plans for students. In addition to predicting the performance of students, it helps teachers and managers to monitor students in order to provide support to them and to integrate the training programs to obtain the best results. One of the benefits of student’s prediction is that it reduces the official warning signs as well as expelling students because of their inefficiency. Prediction provides support to the students themselves through their choice of courses and study plans appropriate to their abilities. The proposed method used deep neural network in prediction by extracting informative data as a feature with corresponding weights. Multiple updated hidden layers are used to design neural network automatically; number of nodes and hidden layers controlled by feed forwarding and backpropagation data are produced by previous cases. The training mode is used to train the system with labeled data from dataset and the testing mode is used for evaluating the system. Mean absolute error (MAE) and root mean squared error (RMSE) with accuracy used for evolution of the proposed method. The proposed system has proven its worth in terms of efficiency through the achieved results in MAE (0.593) and RMSE (0.785) to get the best prediction.
Countries have sought to stop the spread of coronavirus disease 2019 (COVID-19) by severely restricting travel and in-person commercial activities. Here, we analyse the supply-chain effects of a set ...of idealized lockdown scenarios, using the latest global trade modelling framework. We find that supply-chain losses that are related to initial COVID-19 lockdowns are largely dependent on the number of countries imposing restrictions and that losses are more sensitive to the duration of a lockdown than its strictness. However, a longer containment that can eradicate the disease imposes a smaller loss than shorter ones. Earlier, stricter and shorter lockdowns can minimize overall losses. A 'go-slow' approach to lifting restrictions may reduce overall damages if it avoids the need for further lockdowns. Regardless of the strategy, the complexity of global supply chains will magnify losses beyond the direct effects of COVID-19. Thus, pandemic control is a public good that requires collective efforts and support to lower-capacity countries.
Abstract
As demonstrated during the COVID-19 pandemic, advanced deep ultraviolet (DUV) light sources (200–280 nm), such as AlGaN-based light-emitting diodes (LEDs) show excellence in preventing virus ...transmission, which further reveals their wide applications from biological, environmental, industrial to medical. However, the relatively low external quantum efficiencies (mostly lower than 10%) strongly restrict their wider or even potential applications, which have been known related to the intrinsic properties of high Al-content AlGaN semiconductor materials and especially their quantum structures. Here, we review recent progress in the development of novel concepts and techniques in AlGaN-based LEDs and summarize the multiple physical fields as a toolkit for effectively controlling and tailoring the crucial properties of nitride quantum structures. In addition, we describe the key challenges for further increasing the efficiency of DUV LEDs and provide an outlook for future developments.
Abstract
Economic growth is principally powered by energy fuels. While the potential energy transition pathways in developed countries are clear, they have not been well explored for developing ...countries. Here, we study the average annual growth rate of energy consumption in 12 aggregated regions during 2001–2017 and the driving factors behind that growth. The countries with high energy consumption growth rates were concentrated in Asia and North Africa and four of the top five regions were in Asia, while the energy consumption in developed countries was stable or even declined in that period. Therefore, based on a comprehensive consideration of factors such as population and economic development, to quantify the role of renewable energy, we analyze the long time series of energy consumption for China, India, Indonesia, Myanmar and Bangladesh since the 1970s. Despite economic development and population growth accelerating energy consumption substantially upward, energy intensity made energy consumption decrease. Coal and oil dominated the energy transition pathway in China and India, while biomass and natural gas dominated in Indonesia, Myanmar and Bangladesh. The amount of CO
2
emissions in different countries was closely related to the amount and type of the energy they used. Our research results emphasize the importance of improving energy efficiency and adjusting energy structure to reduce energy consumption and achieve sustainable development.
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