Search

Lithium sulfide (Li2S) is a promising alternative cathodic material for lithium–sulfur batteries, which can alleviate the volume expansion of sulfur‑based cathodes. As a fully lithiated cathode, Li2S can be paired with Li-free anodes, thereby increasing the selectivity of anodic materials. Nevertheless, Li2S cathode is hindered by its high cost, harsh preparation conditions, and inadequate conductivity, which impose limitations on its practical application. Hence, the crucial factor in enabling the practicality of Li2S cathode is the development of low-cost and facile synthetic methods to produce highly conductive Li2S material. Herein, a high‑conductivity Li2S@C/CNT composite cathode is prepared using low-cost Li2SO4 as a lithium source through a facile spray drying technique combined with carbothermal reduction method. Benefiting from the high-speed three-dimensional pathway for electron transport provided by the in-situ formed botryoidal highly conductive network, the Li2S@C/CNT cathode exhibits ultrahigh initial discharge capacity (1028.5 mA h g− 1@1 C), superior cycle stability (520.6 mA h g− 1 after 200 cycles), and remarkable rate capability (301.8 mA h g− 1@5 C). This work not only presents a simple and feasible approach for the low-cost preparation of high‑performance Li2S cathode, but also proposes an innovative idea for advancing the development of high energy density lithium–sulfur batteries. [ABSTRACT FROM AUTHOR]

All-solid-state lithium–sulfur batteries are considered one of the most promising candidates for energy storage devices due to their high energy density and safety. However, the poor electron transport of sulfur-based cathodes significantly reduces their reaction kinetics, resulting in low utilization efficiency and subpar rate performance. Herein, leveraging the similar chemical properties of sulfur and selenium, we uniformly deposit SexS1−x (x = 0–0.3) solid solutions with different selenium content on the surface of active carbon via a facile melt-diffusion method to achieve SexS1−x@AC (x = 0–0.3) composite materials. The introduction of selenium effectively enhances the lithium-ion diffusion coefficient of the SexS1−x@AC (x = 0–0.3) cathodes, and improves the stability of the cathode/solid electrolyte interface. With the increase in selenium content, the reaction kinetics of the SexS1−x@AC (x = 0–0.3) cathodes are altered. Specifically, the average lithium-ion diffusion coefficients for the S@AC and Se0.2S0.8@AC cathodes are 6.11 × 10−14 and 1.65 × 10−13 cm2 s−1, respectively, showing a twofold increase. Concurrently, the Se0.2S0.8@AC cathode exhibits higher discharge capacity (698.8 mA h g−1) than that of the S@AC cathode (501.3 mA h g−1) at 1 A g−1. Surprisingly, even when the mass loading increases to 8.85 mg cm−2, the Se0.2S0.8@AC cathode still shows superior cycling stability, which is attributed to the fast ionic/electronic transport pathways within the cathode. Moreover, the Se0.2S0.8@AC cathode maintains good physical contact at the cathode/SE interface after cycling. In all-solid-state lithium–sulfur batteries, the introduction of selenium in the sulfur cathode enhances reaction kinetics (1.65 × 10−13 cm2 s−1), provides additional reactive sites, and significantly improves the electrochemical performance of Se0.2S0.8@AC even with high mass loading (8.85 mg cm−2). [ABSTRACT FROM AUTHOR]

This study aimed to investigate the value of tissue doppler imaging (TDI) and 4D myocardial strain parameters in evaluating left heart function of pregnant women with hypertension and the association between these parameters and relevant factors. Forty-five pregnant women with hypertensive disorder, including 20 with hypertension, 15 with mild preeclampsia, and 10 with severe preeclampsia, were recruited, and their cardiac functions were compared with those of 30 healthy pregnant women as controls. High Left ventricular end-systolic volume (LVESV), Left atrial volume index (LAVI), E/e were observed in hypertensive disorder, while Mitral peak diastolic velocity(E), Early diastolic peak velocity(e), E/A, Left ventricularglobal longitudinal strain (LVGLS), Left ventricularglobal area strain (LVGAS), and Left atrialglobal longitudinal strain (LAGLS) were decreased; for pre-eclampsia, Left ventricular end-systolic diameter (LVESD), Left atrial anteroposterior diameter (LAD-ap), LVESV, LAVI were significantly increased, LVGLS, LAGLS were significantly decreased, Left ventricular end-diastolic diameter (LVEDD), Left ventricular end-diastolic volume (LVEDV), A peak, E/e were increased, while E peak, E/A, e, Left ventricle global radial strain (LVGRS), Left ventricle global circumferential strain (LVGCS), LVGAS were decreased but not significantly; for severe preeclampsia, Left ventricular end diastolic diameter (LVEDD), LVESD, LAD-ap, Left ventricular end-diastolic volume (LVEDV), LVESV, LAVI, A, and E/e were significantly increased, while LVGLS, LVGRS, LVGCS, LVGAS, LAGLS, E peak, E/A, and e were significantly reduced. TDI combined with 4D myocardial strain parameters can detect early changes in cardiac function of hypertensive disorders in pregnancy, with LVGLS, LVGAS, and LAGLS being the most sensitive indicators for early changes. Such findings provide a basis for effective clinical treatment of these symptoms. [ABSTRACT FROM AUTHOR]

This paper discusses the challenges of mobile edge computing with low latency and energy consumption caused by the explosive growth of communication traffic and data generated by mobile devices. To address the issue of selecting edge servers, a multi-user-oriented edge server selection strategy is proposed. The strategy minimizes the weighted sum of network latency and total energy consumption and develops an improved SPEA2-based algorithm to choose the most suitable edge server. The resource allocation problem is also considered, and a resource allocation strategy is proposed that maximizes the energy efficiency ratio. A DQN-based resource allocation strategy is devised to find the best resource allocation strategy. Experimental results demonstrate that the proposed server selection strategy reduces system overhead in terms of energy consumption and latency while improving resource utilization. The resource allocation strategy improves the computational efficiency of edge servers while reducing latency and total energy consumption. [ABSTRACT FROM AUTHOR]

Owing to the high specific capacity and cost-effectiveness, cobalt-free high-nickel cathode materials (LiNixMn1−xO2, x > 0.5) are widely used in lithium-ion batteries for various electronic equipment and energy storage systems. However, their unsatisfactory electrochemical performance and relatively high cost still limit the large-scale application of LiNixMn1−xO2 cathodes. Herein, we propose a series of blended LiNi0.6Mn0.4O2(NM64)/LiMn2O4(LMO) cathode materials synthesized by a simple mechanical mixing method to significantly reduce the cathode material cost, as well as to ameliorate the cycling life span and rate ability. It is demonstrated that this feasible and economic blending strategy fully exploits the advantages of high-specific-capacity NM64 with a layered structure and low-cost LMO with a spinel structure, which could effectively compensate for the inferior rate performance of NM64 and the poor cycling performance of LMO. Specifically, when the mass ratio of NM64 to LMO is 85:15, the NM64 and LMO particles not only uniformly fill their respective inter-particle gaps, effectively increasing the compaction density of the binary blended materials, but also exhibit comprehensively enhanced electrochemical properties in terms of high specific capacity (154.29 mA h g−1 at the first cycle), long cycling life span (79.7% at 0.2C after 100 cycles), and excellent rate performance (70.70 mA h g−1 at 2C). Such ingeniously designed cobalt-free oxides cathode will pave the new avenue in the sustainable development of economical oxides cathodes for high-performance lithium-ion batteries. [ABSTRACT FROM AUTHOR]

With the scarcity of cobalt resources and soaring prices, the removal of cobalt from nickel-rich layered cathodes is now a priority to reduce the material costs and develop the sustainability of lithium-ion batteries (LIBs). In this work, we report a single-crystal cobalt-free LiNi0.6Mn0.4O2 (NM64) layered oxide cathode and compare it with single-crystal LiNi0.6Co0.1Mn0.3O2 (NCM613) cathode. On the one hand, NM64 exhibits competitive energy density to NCM613 and better long-term cycle stability under a high cutoff voltage of 4.5 V. Impressively, single-crystal NM64 not only could effectively suppress the microcrack formation, resulting in the excellent structural stability and long cycling lifespan even at the full delithiated state, but also, it has superior thermal stability to single-crystal NCM613, which is beneficial to achieve high operational safety of LIBs. On the other hand, due to the removal of expensive cobalt, the material cost of NM64 is only 2/3 of NCM613, which is conducive to significantly reducing the cost of LIBs. As a result, NM64 exhibits high energy density (765.27 Wh kg−1) and remarkable cycle stability (93.21 mA h g−1 after 200 cycles at a high charging voltage of 4.5 V). Considering the cost and electrochemical performance advantages, the NM64 cathode is highly expected to stand out in the next generation of cobalt-free LIBs. [ABSTRACT FROM AUTHOR]

Depending on various government policies, COVID-19 (Corona Virus Disease-19) lockdowns have had diverse impacts on global aerosol concentrations. In 2022, Changchun, a provincial capital city in Northeast China, suffered a severe COVID-19 outbreak and implemented a very strict lockdown that lasted for nearly two months. Using ground-based polarization Light Detection and Ranging (LiDAR), we detected real-time aerosol profile parameters (EC, extinction coefficient; DR, depolarization ratio; AOD, aerosol optical depth), as well as air-quality and meteorological indexes from 1 March to 30 April in 2021 and 2022 to quantify the effects of lockdown on aerosol concentrations. The period in 2022 was divided into three stages: pre-lockdown (1–10 March), strict lockdown (11 March to 10 April), and partial lockdown (11–30 April). The results showed that, during the strict lockdown period, compared with the pre-lockdown period, there were substantial reductions in aerosol parameters (EC and AOD), and this was consistent with the concentrations of the atmospheric pollutants PM2.5 (particulate matter with an aerodynamic diameter ≤ 2.5 µm) and PM10 (particulate matter with an aerodynamic diameter ≤ 10 µm), and the O3 concentration increased by 8.3%. During the strict lockdown, the values of EC within 0–1 km and AOD decreased by 16.0% and 11.2%, respectively, as compared to the corresponding period in 2021. Lockdown reduced the conventional and organized emissions of air pollutants, and it clearly delayed the time of seasonal emissions from agricultural burning; however, it did not decrease the number of farmland fire points. Considering meteorological factors and eliminating the influence of wind-blown dust events, the results showed that reductions from conventional organized emission sources during the strict lockdown contributed to a 30% air-quality improvement and a 22% reduction in near-surface extinction (0–2 km). Aerosols produced by urban epidemic prevention and disinfection can also be identified using the EC. Regarding seasonal sources of agricultural straw burning, the concentrated burning induced by the epidemic led to the occurrence of heavy pollution from increased amounts of atmospheric aerosols, with a contribution rate of 62%. These results indicate that there is great potential to further improve air quality in the local area, and suggest that the comprehensive use of straw accompanied by reasonable planned burning is the best way to achieve this. [ABSTRACT FROM AUTHOR]

CNC machine tools play an extremely important role in the equipment manufacturing industry. Because a machine tool has multiple geometric errors which are highly coupled, the error identification process is difficult. Most direct and indirect measurement methods do not consider the dynamic errors in the actual cutting process. This study aims to optimize the error identification process of three-axis CNC machine tools, and proposes an efficient identification and separation method for the dynamic error and the quasi-static error based on feature workpiece cutting. In this study, a stepped feature workpiece that can reflect geometric errors is designed, and the mapping relationship between the geometric error components and the features is established. After the feature workpiece is cut, it performs two tests of on-machine measurement and CMM calibration sequentially. It can realize the identification and separation of 7 geometric errors and corresponding dynamic errors based on the two sets of test data. This method takes the actual cutting workpiece as the error source and can identify and separate the dynamic error and the quasi-static error simultaneously. Thus, the measurement efficiency of this method is higher than direct measurements. The geometric error identification result is highly consistent with the laser interferometer measurement, which proves the method in this study is feasible, efficient, and accurate. [ABSTRACT FROM AUTHOR]

Uncertainty assessments of hydrological prediction results can reflect additional hydrological information and reveal important hydrological characteristics of river basins, which is of great significance to disaster prevention and reduction. The hydrological uncertainty processor (HUP), which is a key part of the Bayesian forecasting system (BFS), has derived a variety of methods for hydrological uncertainty forecasting. The HUP allows for any form of marginal distributions of hydrological data and does not require a unified estimation structure for the marginal distribution function. The Gaussian mixture model (GMM) is a probability distribution estimation model that can approximate any probability distribution with arbitrary precision. In this paper, the GMM was used to estimate the marginal distribution of observed and modelled data, and this method is called HUP-GMM. The uncertainty of river discharge at the Yichang hydrological station on the main stem of the Yangtze River in China is predicted by the HUP-GMM. The Weibull and Gamma distributions, which are commonly used hydrological probability distributions, are compared to analyse the performance of the GMM. In June, when the measured flow h3 is 13,850 m3/s and the GMM, Gamma and Weibull distributions are used, the prior probabilities are 1.63E-04, 1.05E-04 and 9.50E-05 and the posterior probabilities are 2.57E-04, 1.61E-04 and 1.38E-04, respectively. In September, when the measured flow h3 is 35,400 m3/s and the GMM, Gamma and Weibull distributions are used, the prior probabilities are 5.98E-05, 2.21E-05 and 2.18E-05 and the posterior probabilities are 1.64E-04, 9.15E-05 and 8.43E-05, respectively. The results show that the performance of the uncertainty estimation of the prior and posterior probability distributions in the HUP-GMM has been improved. [ABSTRACT FROM AUTHOR]

The Yangtze River Economic Belt is one of the three national strategies of China, while flood risk is one of the most important concerns in the development of Yangtze River Economic Belt. In order to decrease the risks caused by floods, complete flood management system and adequate pre-arranged planning are desiderated to be researched in advance. This study considers two typical situations of flood risk, in which one is sluice-control situation in flood detention area and another is dike-break situation in flood-protected area, and proposes a framework for flood risk mapping. The results show that the losses caused by flood hazards are massive both in the two typical cases when extreme floods happen. The economic losses of different indicators are of great difference in flood detention area and flood-protected area, respectively. The framework effectively handles the complex boundaries in the Yangtze River Economic Belt and provides more accurate flood routing information. The evacuation plan module which has been incorporated in the framework also provides informative assistance for emergent action of evacuation under urgent condition. [ABSTRACT FROM AUTHOR]

LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode material is prized in the electric vehicles (EVs) industry for its high capacity and voltage during operation. However, the high residual alkali content and inferior ionic conductivity of Ni‑rich cathode materials are the intractable obstacles to the large-scale commercial application for a long time. Herein, a feasible Nb2O5 coating strategy is proposed to eliminate residual alkali along with constructing high Li+ conductive coating layer on NCM811 cathode materials surface. Impressively, 0.3% Nb2O5‑coated NCM811 cathode exhibits superior rate capability (146.4 mA h g−1@400 mA g−1) and remarkable rate cyclic stability (188.5 mA h g−1 after 100 cycles with capacity retention of 94.8%). On the one hand, a small quantity of Nb2O5 coating on NCM811 surface can react with surface residual alkali to promote the transformation of low electronic conductivity surface residual alkali into the Li+ conductor of LiNbO3 coating layer, enhancing Li+ de-intercalation kinetics and rate performance. On the other hand, excessive Nb2O5 coating may introduce Nb5+ into the lattice of NCM811, acting as pivotal components within the Li+ layer, which effectively suppresses the H2 ↔ H3 phase transition, contributing to long-term cyclic stability. This work paves a new path for the rational design and facile coating of Ni-rich oxide cathode materials with reinforced structure stability and boosted rate capability in high‑energy‑density lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Examines the oxidation of a copper alloy using transmission electron microscopy. Sizes of oxide grains; Formation of grains along the planes of the stacking fault; Occurrence of shape memory effect of the alloy.

TiNb2O7 (TNO) has been regarded as a promising anode material for high-power lithium–ion batteries due to its high theoretical capacity and work voltage (387.6 mA h g−1, 1.6 V vs. Li+/Li). Herein, a series of microspherical TNO anode materials are synthesized by a facile solvothermal method, and the effect of solvothermal time on the microstructure and electrochemical performance is investigated. Specifically, when the solvothermal time is 12 h, the TNO microsphere (TNO-12) exhibits higher specific surface area and more reasonable pore size distribution. As a result, TNO-12 anode delivers a high reversible discharge capacity of 299.87 mA h g−1 with a superior initial coulombic efficiency above 98.5%, excellent cycling capacity retention of 80.15% after 100 cycles at 0.5 C (150 mA g−1), and good rate performance at 0.1–2 C. Most importantly, the full cell constructed with TNO anode and commercial oxide cathode (LiNi0.6Mn0.4O2/LiMn2O4 with a mass ratio of 85: 15) exhibits excellent cycling stability at high current densities (79.14% after 100 cycles at 0.5 C). This study optimizes the synthesis process for high-performance microspherical TNOs, providing new insights for the next generation of commercial anodes. [ABSTRACT FROM AUTHOR]