The present work is focused on the use of electrochemical cathode-reduction method for leaching LiCoO2 produced by spent lithium-ion batteries. The thermodynamics, kinetics, and electrochemical ...impedance spectroscopy analyses are used to determine the probable control mechanism involved in the leaching of cobalt from spent LiCoO2. The leaching efficiencies reached about 90% for cobalt and nearly 94% for lithium using 1.25 mol/L of malic acid and a working voltage of 8 V for 180 min at 70 °C. Kinetics analysis indicates that the leaching process of cobalt could be divided into two stages: the first stage is controlled by a surface chemical reaction, and the second stage is controlled by a combination of the surface chemical reaction and diffusion. Electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy analysis show that the combination control at the second stage is related to the form of Co(OH)3 produced during the leaching process of spent LiCoO2. Finally, a novel process for the leaching of cobalt from spent LiCoO2 is proposed.
•A novel process of electrochemical cathode reduction is designed for leaching of spent LiCoO2 batteries.•The thermodynamics, kinetics and EIS are analyzed for understanding the controlling mechanism of leaching process.•The SEM, XPS and TEM are analyzed for clarifying the combination control at second stage of leaching process.
Microporous nitrogen‐doped carbons produced by hydrothermal carbonization of biomass derivative followed by chemical activation showed excellent supercapacitive capacitance performance both in acid ...and base electrolytes.
•Entropy and entransy theories are reviewed and compared from three perspectives.•Multi-objective optimization with entropy generation cannot meet various demands.•Minimum entropy generation does not ...lead to maximum heat transfer coefficient.•Entransy dissipation extremum corresponds to maximum heat transfer coefficient.•Entransy with Pareto Optimality is more appropriate for heat transfer optimization.
Performance improvement of convective heat transfer processes is significant for energy conservation. Considering the trade-off between the heat transfer enhancement and the pumping power reduction, the optimization of convective heat transfer processes can be modeled as a multi-objective optimization problem in the entropy-based approach and a constrained optimization problem in the entransy-based approach. This article first reviews these two theories and then compares them from the perspectives of optimization criteria, optimization methods and optimization results. Studies have shown that simply analyzing the entropy generation rate or other entropy generation criteria cannot meet the diverse objectives of various practical applications. Besides, the minimum heat transfer entropy generation does not always lead to the maximum of convective heat transfer coefficient, as reason is also analyzed here. In contrast, the entransy dissipation extremum corresponds to the maximum convective heat transfer coefficient as has been shown mathematically. Moreover, the entransy dissipation extremum principle and the variational method can be combined to find the optimal flow and temperature fields with better heat transfer results than determined using the entropy generation minimization principle. The entransy optimization results can then be used to design better augmentation technologies for convective heat transfer processes. In summary, the entransy theory is more appropriate for optimizing convective heat transfer processes without heat-work conversion processes.
Janus MXene-decorated CNFs/luffa (JMCL) aerogel integrated the multifunction of fast water transport, good thermal management, fast vapor escape, and efficient photothermal conversion in a ...single-module. The hydrophobic lower part and hydrophilic upper part perform complementary functions, endowing the JMCL aerogel with high sunlight-to-heat-to-vapor conversion efficiency and self-floating performance. The JMCL aerogels delivered a water evaporation rate of 1.40 kg m-2h−1 and an efficiency of 91.20% under 1 sun illumination. In addition, the mechanical strength of JMCL aerogels is 437 times that of MXene/CNFs aerogels. The excellent salt resistance during 24h working and long-term solar vapor generation of up to 28 days were achieved.
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Interfacial solar steam generation (ISSG) is considered to be an attractive technique to address the water shortage. However, developing a sustainable thermal management, salt rejection, and excellent mechanical strength ISSG device for long-term stability desalination is still a challenge. Herein, a biomass ISSG device with superb mechanical properties was prepared by introducing a luffa sponge as the skeleton and constructing the MXene/cellulose nanofibers (CNFs) aerogels via freeze-drying. The Janus MXene-decorated CNFs/luffa (JMCL) aerogels integrated the multifunction of fast water transport, good thermal management, and efficient photothermal conversion in a single module, to achieve high-efficiency desalination. 3D Janus structure endowed the JMCL aerogel with opposite wettability, which is feasible to construct the localized photothermal generation and self-floating. The mechanical strength of JMCL aerogels is 437 times that of MXene/CNFs aerogels. The JMCL aerogels delivered a water evaporation rate of 1.40 kg m-2h−1 and an efficiency of 91.20% under 1 sun illumination. The excellent salt resistance during 24 h working and long-term solar vapor generation of up to 28 days were achieved. The multifunctional JMCL aerogels with 3D Janus structure offer new insights for developing good durability and eco-friendly biopolymer-based steam generators.
Robust, ultrathin, and environmental‐friendliness papers that synergize high‐efficiency electromagnetic interference (EMI) shielding, personal thermal management, and wearable heaters are essential ...for next‐generation smart wearable devices. Herein, MXene nanocomposite paper with a nacre‐like structure for EMI shielding and electrothermal/photothermal conversion is fabricated by vacuum filtration of Ti3C2Tx MXene and modified sawdust. The hydrogen bonding and highly oriented structure enhance the mechanical properties of the modified sawdust/MXene composite paper (SM paper). The SM paper with 50 wt% MXene content shows a strength of 23 MPa and a toughness of 13 MJ·M−3. The conductivity of the SM paper is 10 195 S·m−1, resulting in an EMI shielding effectiveness (SE) of 67.9 dB and a specific SE value (SSE/t) of 8486 dB·cm2·g−1. In addition, the SM paper exhibits excellent thermal management performance including high light/electro‐to‐thermal conversion, rapid Joule heating and photothermal response, and sufficient heating stability. Notably, the SM paper exhibits low infrared emissivity and distinguished infrared stealth performance, camouflaging a high‐temperature heater surface of 147–81 °C. The SM‐based e‐skin achieves visualization of Joule heating and realizes human motions monitoring. This work presents a new strategy for designing MXene‐based wearable devices with great EMI shielding, artificial intelligence, and thermal management applications.
A TDS/MXene (SM) paper is prepared by Ti3C2Tx and modified sawdust as the smart wearable device, showing a strength of 23 MPa and an EMI SE of 67.9 dB. The SM paper achieves a high Joule heating and photothermal temperature and exhibits notable infrared stealth performance, camouflaging a high‐temperature. The paper‐based e‐skin visualizes Joule heating temperature and monitors human motions.
Convenient generation of stable superatomic silver clusters and their systematic site-specific tailoring and directional assembly present an enduring and significant challenge. In this work, we ...prepared a face-centered cubic (fcc) array of Ag14 superatoms protected by face-capping 1,2-dithiolate-o-carborane (C2B10H10S2) ligands, each produced from 1-thiol-o-carborane in crystallization with simultaneous reduction of Ag+ to Ag0. We find that the corner N-donor ligands contribute predominately to the stability and luminescence of the Ag14 superatom. As the first-formed nanocluster Ag14(C2B10H10S2)6(CH3CN)8·4CH3CN (NC-1) with labile vertex-coordinated CH3CN ligands is highly unstable, monodendate pyridine ligands were used to replace these CH3CN species site-specifically, giving Ag14(C2B10H10S2)6(pyridine/p-methylpyridine)8 (NCs-2,3) in gram scale with its core structure intact, which features ultrastability up to 150 °C in air. Moreover, using bidentate N-containing ligands to bridge the superatomic Ag14 building blocks, we constructed an unprecedented hierarchical series of 1D-to-3D superatomic silver cluster-assembled materials (SCAM-1,2,3,4), and SCAM-4 is air-stable up to 220 °C. Furthermore, this series of stable solid-state superatomic-nanocluster materials exhibit tunable dual emission with wide-range thermochromism. The present study constitutes a major step toward the development of ligand-modulation of the structure, stability, assembly, and functionality of superatomic silver nanoclusters.
Achieving lightweight, robust, and resilient materials is a sought-after goal, yet concurrently achieving these attributes presents a substantial challenge. A biomimetic design approach opens doors ...to innovative possibilities in this domain. In this paper, we use the ice-shaping properties of zirconium acetate (ZRA) to obtain Al/Al2O3 composites with tunable architectures through freeze casting and pressure infiltration. The concentration of ZRA in the initial slurry is critical in controlling the final structure of the composites. The composites’ bending strength, compressive strength, and crack-initiation fracture toughness KIc improve with increasing ZRA concentration in the initial slurry. Interestingly, the crack-extension fracture toughness KJc demonstrates an initial decrease followed by subsequent improvement. In addition, the relationship between cracking mode and structural features in the composites is elucidated to explain the underlying strengthening and toughening mechanisms. This tunable and scale-able ice-templating and manufacturing approach opens new doors for developing high-performance metal-ceramic composites.
In modern Russia it is widely believed that China has adopted all the best from the USSR: the ideas of the equality of citizens, the socialist structure of the state, the fight against corruption, ...cultural trends, trends in education. The Russian village prose has become part of the school curriculum of China, just as it has done in its homeland in Russia. Rustic prose is close in spirit to the bulk of the population of the Chinese provinces. The ideas and trends that concern the Russian people could not leave the citizens of China indifferent. Russian literature has been influencing the national literature of China since 1917; using the example of the works of Russian literature, the people of China realized the need for change, writers understood the basics of creating new, modern literature. In the 90s, the place of the Russian village prose was so great that the Chinese population perceived it as their native literature. In China, the works of V. Astafyev, V. Rasputin, V. Shukshin are appreciated, the peculiarities of the writers’ styles are studied. The works written in the genre of rustic prose are of great importance for Chinese citizens, they fall out of the usual genre, preserve the historical memory of the people, show the tragedies of the times of collectivization, the hardships of wartime logistics, the restoration of the destroyed state, and others.Village life fascinates with its simplicity. Breaking away from his roots, destroying intra-family ties, being carried away by opposing tendencies and ideas, the hero of the works of Russian authors makes himself unhappy, but the understanding of the mistake comes to him late, alongside the remorse, or does not come at all.
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•SBSE in combination with GC–MS was applied in Longjing tea aroma analysis.•A total of 151 volatile compounds were identified and quantified.•Fourteen compounds were distinguished as ...the most important key aroma compounds.•Dimethyl sulfoxide was first recognized as a key aroma compound in Longjing tea.
Longjing tea is the most famous premium green tea, and is regarded as the national tea in China, with its attractive aroma contributing as a prime factor for its general acceptability; however, its key aroma compounds are essentially unknown. In the present study, volatile compounds from Longjing tea were extracted and examined using stir bar sorptive extraction (SBSE) combined with gas chromatography-mass spectrometry (GC–MS). Data obtained from the present study revealed that 151 volatile compounds from 16 different chemical classes were identified by GC–MS analysis. Enols (8096 µg/kg), alkanes (6744 µg/kg), aldehydes (6442 µg/kg), and esters (6161 µg/kg) were the four major chemical classes and accounted for 54% of the total content of volatile compounds. Geraniol (6736 µg/kg) was the most abundant volatile compound in Longjing tea, followed by hexanal (1876 µg/kg) and β-ionone (1837 µg/kg). Moreover, 14 volatile compounds were distinguished as the key aroma compounds of Longjing tea based on gas chromatography-olfactometry (GC-O) analysis, odor activity value (OAV) calculations, and a preliminary aroma recombination experiment, including 2-methyl butyraldehyde, dimethyl sulfoxide, heptanal, benzaldehyde, 1-octen-3-ol, (E, E)-2,4-heptadienal, benzeneacetaldehyde, linalool oxide I, (E, E)-3,5-octadien-2-one, linalool, nonanal, methyl salicylate, geraniol, and β-ionone. This is the first comprehensive report describing the aroma characterizations and the key aroma compounds in Longjing tea using SBSE/GC–MS. The findings from this study contribute to the scientific elucidation of the chemical basis for the aromatic qualities of Longjing tea.
Extracellular vesicles (EVs), including exosomes and microvesicles, are present in a variety of bodily fluids, and the concentration of these sub-cellular vesicles and their associated biomarkers ...(proteins, nucleic acids, and lipids) can be used to aid clinical diagnosis. Although ultracentrifugation is commonly used for isolation of EVs, it is highly time-consuming, labor-intensive and instrument-dependent for both research laboratories and clinical settings. Here, we developed an integrated double-filtration microfluidic device that isolated and enriched EVs with a size range of 30-200 nm from urine, and subsequently quantified the EVs via a microchip ELISA. Our results showed that the concentration of urinary EVs was significantly elevated in bladder cancer patients (n = 16) compared to healthy controls (n = 8). Receiver operating characteristic (ROC) analysis demonstrated that this integrated EV double-filtration device had a sensitivity of 81.3% at a specificity of 90% (16 bladder cancer patients and 8 healthy controls). Thus, this integrated device has great potential to be used in conjunction with urine cytology and cystoscopy to improve clinical diagnosis of bladder cancer in clinics and at point-of-care (POC) settings.
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