Biodegradable poly(lactic acid) (PLA)/poly(butylene adipate‐co‐terephthalate) (PBAT) blends and PLA/PBAT/Al2O3 nanocomposites were fabricated via solution blending. The influence of PBAT and Al2O3 ...content on the thermal stability, flexural properties, impact strength, and morphology of both the PLA/PBAT blends and the PLA/PBAT/Al2O3 nanocomposites were investigated. The impact strength of the PLA/PBAT/Al2O3 nanocomposites containing 5 wt% PBAT increased from 4.3 to 5.2 kJ/m2 when the Al2O3 content increased from 0 to 1 wt%. This represents a 62% increase compared to the impact strength of pristine PLA and a 20% increase compared to the impact strength of PLA/PBAT blends containing 5 wt% PBAT. Scanning electron microscopy imaging revealed that the Al2O3 nanoparticles in the PLA/PBAT/Al2O3 nanocomposites function as a compatibilizer to improve the interfacial interaction between the PBAT and the PLA matrix.
As one of the fascinating high capacity cathodes, O3‐type layered oxides usually suffer from their intrinsic air sensitivity and sluggish kinetics originating from the spontaneous lattice Na ...extraction during air exposure and high tetrahedral site energy of Na+ diffusion transition state. What is worse, the improvement on the two handicaps is hard to simultaneously realize because of the contradiction between Na containment suggested in air stability mechanism and enhanced Na diffusion mentioned in kinetics strategy. Herein, it is shown that a simple strategy of introducing proper Na vacancies into lattice can simultaneously realize a dual performance improvement. Na vacancies decrease the charge density on transitional metal ions and enhance the antioxidative capability of material, ensuring a stable lattice Na containment for Na0.93Li0.12Ni0.25Fe0.15Mn0.48O2 when exposed to air. Additionally, more Na+ diffusional sites and enlarged Na layer spacing are obtained and result in a significantly decreased energy barrier from ≈1000 to 300 meV and a high rate capability of 70.8% retention at 2000 mA g−1. Remarkably, such a strategy can be easily realized by either pre‐ or post‐treating, which exhibits excellent universality for various O3 materials, implying its enormous potential to promote the commercial application of O3‐type cathodes.
A universal strategy of introducing proper Na vacancies into a crystal lattice is proposed to simultaneously improve air‐stability and kinetics of O3‐type layered oxide cathodes. The dual improvement benefits from the multiple effects of Na vacancies on crystalline and electronic structure, namely, decreased charge density on transition metal ions, enhanced antioxidative capability, decreased Na+ diffusion barrier, and optimized migration path.
In the network economy domain, urban competitiveness refers to the comparison between cities in terms of competition and development. It is the ability to gain competitive advantage under different ...factors. The evaluation of urban competitiveness will help cities to learn from each other, and provides reference for the government to enhance urban competitiveness. Unlike various studies in the literature exploiting only the non-linear characteristics of urban competitiveness, this paper selects BP (Back Propagation) network as the main framework for evaluation. A Genetic Algorithm BP (GABP) network based on genetic optimization is utilized. The weights are optimized besides the crossover mutation of GA algorithm. To compensate the slow prediction in the stand-alone mode, this work proposes a MapReduce (MP) based method; MR-GABP via cloud computing. The model ensures effective urban competitiveness evaluation with improved convergence speed and threshold generation speed. The systematic experiments conducted verify effectiveness of the method while the results obtained reveal that performance of the method is better than the other methods in terms of accuracy and recall yielded as 95.1% and 92.6% respectively.
A subzero‐temperature cathode material is obtained by nucleating cubic prussian blue crystals at inhomogeneities in carbon nanotubes. Due to fast ionic/electronic transport kinetics even at −25 °C, ...the cathode shows an outstanding low‐temperature performance in terms of specific energy, high‐rate capability, and cycle life, providing a practical sodium‐ion battery powering an electric vehicle in frigid regions.
The uncontrolled growth of Li dendrites upon cycling might result in low coulombic efficiency and severe safety hazards. Herein, a lithiophilic binary lithium–aluminum alloy layer, which was ...generated through an in situ electrochemical process, was utilized to guide the uniform metallic Li nucleation and growth, free from the formation of dendrites. Moreover, the formed LiAl alloy layer can function as a Li reservoir to compensate the irreversible Li loss, enabling long‐term stability. The protected Li electrode shows superior cycling over 1700 h in a Li|Li symmetric cell.
Dendrite‐free anodes: An efficient lithium–aluminum alloy medium with increased affinity for Li and generated through an in situ electrochemical process is engineered to guide uniform Li nucleation and suppress the growth of Li dendrites.
Owing to its excellent mechanical properties, processability, and biodegradability, poly(lactic acid) (PLA) has been widely investigated in the past few decades as a biomaterial. However, the poor ...heat resistance of PLA severely limits its applicability. In this review, several heat resistance modification methods, such as nucleating agent addition, fiber reinforcement, compounding, blending, stereoisomer complexation, and chemical modification, have been reviewed and their related mechanisms have been discussed in brief.
With the development of connected automated vehicles (CAVs) technologies, traffic flow on the road is converting into the heterogeneous traffic flow, which consists of CAVs and human-driven vehicles ...(HDVs). Considering the function of CAVs would degrade when following HDVs in heterogeneous traffic flow. Moreover, the reaction time of degraded CAVs would be different with CAVs or HDVs. This paper deduces and analyzes the linear stability of such heterogeneous traffic flow based on CAVs degradations and reaction time diversity. Firstly, considering the degradations of CAVs, the vehicle types and their ratios in heterogeneous traffic flow are analyzed. Secondly, the car-following model and the reaction time of three types of vehicles are discussed. Then, the linear stability condition of heterogeneous traffic flow is proposed. Finally, the impact factors on the stability condition are illustrated through numerical analysis. The results show that the high penetration rate of CAVs and the short reaction time can improve the linear stability of heterogeneous traffic flow. Besides, when the penetration rate of CAVs increases to 65%, the stability of heterogeneous traffic flow is not affected by speed. Furthermore, the analysis shows that CAVs degradations also has a negative effect on linear stability.
•The linear stability condition based on three types of vehicles and reaction time is derived.•The impacts of CAVs’ penetration rate and reaction time on stability are analyzed.•The critical penetration rate of CAVs independent of speed is obtained under the impact of DCAVs.
This paper first explores and evaluates English-Chinese translation skills through deep learning in machine learning based on big data technology, focusing on applying convolutional neural networks ...and long and short-term memory network models in English-Chinese translation. Then it is to construct a deep learning evaluation model based on the dataset with text-level labels of English-Chinese translation. The structure of the deep learning evaluation model consists of three categories: data representation of text, feature extraction of text, and text classifier. Finally, the research object is determined from the purpose of the study, and the data analysis is performed on the experimental and control groups using the deep learning model to characterize the fluency by the continuous convergence of the data. The results showed that the continuous convergence of the experimental group remained in the range of 76.95% to 82.6%, and its average value was 79.76%. The continuous convergence of the control group remained in the range of 60.15% to 71.92%, with a mean value of 67.02%. The average convergence value of the experimental group was 12.74% higher than that of the control group, and the experimental group outperformed the control group. This study should learn and cultivate English-Chinese translation skills while improving the efficiency and accuracy of English-Chinese translation, which is a guiding reference value for the progress of translation talents.
Rechargeable magnesium batteries have attracted recent research attention because of abundant raw materials and their relatively low‐price and high‐safety characteristics. However, the sluggish ...kinetics of the intercalated Mg2+ ions in the electrode materials originates from the high polarizing ability of the Mg2+ ion and hinders its electrochemical properties. Here we report a facile approach to improve the electrochemical energy storage capability of the Li4Ti5O12 electrode in a Mg battery system by the synergy between Mg2+ and Li+ ions. By tuning the hybrid electrolyte of Mg2+ and Li+ ions, both the reversible capacity and the kinetic properties of large Li4Ti5O12 nanoparticles attain remarkable improvement.
Synergy between Mg2+ and Li+ ions: By controlling the collaborative electrochemistry of magnesium and lithium cations, Li4Ti5O12 electrodes (LTO; see picture) close to sub‐micron size gain extraordinary electrochemical energy storage capability. The electrodes show improved kinetics in rechargeable magnesium batteries.
As one of the most promising cathode candidates for room‐temperature sodium‐ion batteries (SIBs), P2‐type layered oxides face the challenge of simultaneously realizing high‐rate performance while ...achieving long cycle life. Here, a stable Na2/3Ni1/6Mn2/3Cu1/9Mg1/18O2 cathode material is proposed that consists of multiple‐layer oriented stacking nanoflakes, in which the nickel sites are partially substituted by copper and magnesium, a characteristic of the material that is confirmed by multiscale scanning transmission electron microscopy and electron energy loss spectroscopy techniques. Owing to the optimal morphology structure modulation and chemical element substitution strategy, the electrode displays remarkable rate performance (73% capacity retention at 30C compared to 0.5C) and outstanding cycling stability in Na half‐cell system couple with unprecedented full battery performance. The underlying thermal stability, phase stability, and Na+ storage mechanisms are clearly elucidated through the systematical characterizations of electrochemical behaviors, in situ X‐ray diffraction at different temperatures, and operando X‐ray diffraction upon Na+ deintercalation/intercalation. Surprisingly, a quasi‐solid‐solution reaction is switched to an absolute solid‐solution reaction and a capacitive Na+ storage mechanism is demonstrated via quantitative electrochemical kinetics calculation during charge/discharge process. Such a simple and effective strategy might reveal a new avenue into the rational design of excellent rate capability and long cycle stability cathode materials for practical SIBs.
A stable copper and magnesium cosubstituted Na2/3Ni1/6Mn2/3Cu1/9Mg1/18O2 cathode material consisting of multiple‐layer oriented stacking nanoflakes is reported. An optimal structure design and a chemical element substitution strategy are demonstrated to greatly improve Na+ transport kinetics and structural stability of P2‐type cathode material, resulting in high‐rate and long cycle life for a sodium‐ion battery.
