Direct ink writing technology is capable of using 2D MXene to construct 3D architectures for electrochemical energy storage (EES) devices that are normally difficult to achieve using conventional ...techniques. However, to meet specific rheological requirements for 3D printing, a large amount of MXene is needed in the ink, resulting in a severe self‐restacking structure after drying. Herein, a series of cellulose nanofibers (CNFs) with different morphologies and surface chemistries are applied to enhance the rheology of the MXene‐based inks with exceptional 3D printability. Various 3D architectures with superior shape fidelity and geometric accuracy are successfully printed using the optimized hybrid ink at a low solid content, generating self‐standing, hierarchically porous structures after being freeze‐dried, which improves surface area accessibility, ion transport efficiency, and ultimately, capacitive performance. A solid‐state interdigitated symmetrical supercapacitor is further 3D printed, which delivers an areal capacitance of 2.02 F cm−2 and an energy density of 101 μWh cm−2 at a power density of 0.299 mW cm−2, and maintains a capacitance retention rate of 85% after 5000 cycles. This work demonstrates the integration of 1D CNFs and 2D MXene in 3D printing technology to prepare customized, multiscale, and multidimensional architectures for the next generation of EES devices.
By rationally controlling the dimension and surface chemistry of cellulose nanofibers (CNFs), CNFs are successfully applied as rheology modifiers to formulate viscoelastic, 3D printable MXene‐based ink at a low solid concentration of 8 wt%. The freestanding, hierarchically porous MXene‐based electrode architectures can be achieved by 3D printing and freeze‐drying, which holds great potential in electrochemical energy storage devices.
Abstract
Background
Understanding the long-term effects of coronavirus disease 2019 (COVID-19) on cognitive function is essential for monitoring the cognitive decline in the elderly population. This ...study aims to assess the current cognitive status and the longitudinal cognitive decline in elderly patients recovered from COVID-19.
Methods
This cross-sectional study recruited 1539 COVID-19 inpatients aged over 60 years who were discharged from three COVID-19-designated hospitals in Wuhan, China, from February 10 to April 10, 2020. In total, 466 uninfected spouses of COVID-19 patients were selected as controls. The current cognitive status was assessed using a Chinese version of the Telephone Interview of Cognitive Status-40 (TICS-40) and the longitudinal cognitive decline was assessed using an Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE). Cognitive assessments were performed 6 months after patient discharge.
Results
Compared with controls, COVID-19 patients had lower TICS-40 scores and higher IQCODE scores TICS-40 median (IQR): 29 (25 to 32) vs. 30 (26 to 33),
p
< 0.001; IQCODE median (IQR): 3.19 (3.00 to 3.63) vs. 3.06 (3.00 to 3.38),
p
< 0.001. Severe COVID-19 patients had lower TICS-40 scores and higher IQCODE scores than non-severe COVID-19 patients TICS-40 median (IQR): 24 (18 to 28) vs. 30 (26 to 33),
p
< 0.001; IQCODE median (IQR): 3.63 (3.13 to 4.31) vs. 3.13 (3.00 to 3.56),
p
< 0.001 and controls TICS-40 median (IQR): 24 (18 to 28) vs. 30 (26 to 33),
p
< 0.001; IQCODE median (IQR) 3.63 (3.13 to 4.31) vs. 3.06 (3.00 to 3.38),
p
< 0.001. Severe COVID-19 patients had a higher proportion of cases with current cognitive impairment and longitudinal cognitive decline than non-severe COVID-19 patients dementia: 25 (10.50 %) vs. 9 (0.69 %),
p
< 0.001; Mild cognitive impairment (MCI): 60 (25.21 %) vs. 63 (4.84 %),
p
< 0.001 and controls dementia: 25 (10.50 %) vs. 0 (0 %),
p
< 0.001; MCI: 60 (25.21 %) vs. 20 (4.29 %),
p
< 0.001). COVID-19 severity, delirium and COPD were risk factors of current cognitive impairment. Low education level, severe COVID-19, delirium, hypertension and COPD were risk factors of longitudinal cognitive decline.
Conclusions
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is associated with an increased risk of long-term cognitive decline in elderly population. COVID-19 patients, especially severe patients, should be intensively monitored for post-infection cognitive decline.
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•2D Mxene sheets direct the growth of H2V3O8 nanowires to form an integrated structure.•This composite architecture shows enhanced electrical conductivity, leading to superior rate ...performance and long lifespan.•The flexible solid-state Zn-ion batteries are still workable even at different harsh environments.
Low electrical conductivity of the cathode for rechargeable aqueous Zn-ion batteries (RAZIBs) significantly limits the rate capability and shortens the cycling life. Herein, a highly stable composite is developed as a promising cathode by directly growing non-oriented H2V3O8 nanowires on 2D Mxene sheets. This composite architecture shows enhanced electrical conductivity and faster diffusion for charge transportation, resulting in improved rate performance and prolonged cycling life. Compared with the pristine H2V3O8 (306 mAh·g−1 at 0.2 A·g−1 and 900 cycles at 5 A·g−1), the resultant H2V3O8/Mxene composite exhibits larger specific capacities (365 mAh·g−1 at 0.2 A·g−1) and longer cycling life (≈84% capacity retention over 5600 cycles at 5 A·g−1). Even at 10 and 20 A·g−1, this composite cathode also delivers capacities of 164 and 73 mAh·g−1 for over 1900 and 500 cycles, respectively. Such superior electrochemical performance of RAZIB is ascribed to the enhanced electrical conductivity and improved charge transport kinetics. Furthermore, the reversible co-intercalation electrochemical reaction mechanism of Zn2+ and water was systemically demonstrated through various ex-situ characterizations. Additionally, highly safe and flexible solid-state ZIBs with polyacrylamide/cellulose nanofiber (CNF) hydrogel electrolyte deliver high capacities (317.4 mAh·g−1 at 0.2 A·g−1) and long cycle life (over 6600 cycles at 10 A·g−1). The solid-state batteries are still workable even at different harsh environments, such as freezing at −18 ℃ (152.5 mAh·g−1 at 0.5 A·g−1) and heating at 40 ℃ (307.3 mAh·g−1 at 0.5 A·g−1).
Carbon dots (CDs) have received an increasing amount of attention because of their significant advantages in terms of low toxicity, chemical inertness, tunable fluorescence, good water solubility, ...and physicochemical properties. Due to these desirable properties, they have been used in numerous fields, including chemo- and biosensing, fluorescence imaging, and drug delivery. In this review, we aim to demonstrate the recent progress in the green synthesis and formation mechanism of CDs, and provide guidance for developing CDs with the concepts of green chemistry. In addition, we discuss three kinds of most accepted luminescence origins: surface state, quantum confinement effect and molecular fluorescence. Finally, we systematically summarize the latest progress of CDs in fluorescence sensing applications, including both solution phase sensing and solid phase sensing. Furthermore, the challenges and future direction of CDs in this emerging field are discussed.
We systematically summarize the recent progress in the green synthesis and formation mechanism of CDs with the hope to provide guidance for developing CDs with the concept of green chemistry. In addition, we discuss and organize the current opinions on the fluorescence origin of CDs and the latest progress of CDs in fluorescence sensing applications.
Due to their specific properties, ion-adsorption rare earth mine sites may be a threat for adjacent environments. This work was undertaken to assess whether former mining operations on ion-adsorption ...rare earth mine sites have a significant impact on water bodies and soils of the surrounding environments. Tailing soil materials, stream waters and sediments, and farmland soils were collected from one of the largest ion-adsorption rare earth mine sites worldwide (Southern China). Total concentrations of rare earth elements (REEs), Fe, Al, etc., and pH were measured. Results revealed high concentrations of REEs in tailing soils (392 mg kg−1), stream waters (4460 μg L−1), sediments (462 mg kg−1) and farmland soils (928 mg kg−1) in comparison with control sites. In the tailing profiles, light REEs (LREEs) were preferentially leached compared to middle REEs (MREEs) and heavy REEs (HREEs). Anomalies in tailings and stream water indicated strong soil weathering (Eu) and leaching activities (Ce) within the tailings. The MREE enriched pattern in stream water was more related to water parameters such as Al and Fe oxides, and ligands, than to the source of REEs. Anomalies also indicated that REEs contamination in the farmland soils was mainly originated from the stream water contaminated by the leaching from the tailings. In conclusion, a heavy REEs pollution was recorded in the surrounding environment of ion-adsorption rare earth mine. REEs fractionation, Ce and Eu anomalies provided an insight to the understanding of REEs leaching and soil weathering processes, and REEs environmental fate in rare earth mining area.
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•Heavy REEs contamination at ion-adsorption rare earth mine sites, especially stream waters and farmland soils.•Heavy soil weathering and leaching activities within the tailings in which LREEs were preferentially leached.•REEs fractionation and anomalies facilitate to understand REEs geochemistry within ion-adsorption rare earth mine sites.
The 3D printing technique offers huge opportunities for customized thick‐electrode designs with high loading densities to enhance the area capacity in a limited space. However, key challenges remain ...in formulating 3D printable inks with exceptional rheological performance and facilitating electronic/ion transport in thick bulk electrodes. Herein, a hybrid ink consisting of woody‐derived cellulose nanofibers (CNFs), multiwalled carbon nanotubes (MWCNTs), and urea is formulated for the 3D printing nitrogen‐doped thick electrodes, in which CNFs serve as both dispersing and thickening agents for MWCNTs, whereas urea acts as a doping agent. By systematically tailoring the concentration‐dependent rheological performance and 3D printing process of the ink, a variety of gel architectures with high geometric accuracy and superior shape fidelity are successfully printed. The as‐printed gel architecture is then transformed into a nitrogen‐doped carbon block with a hierarchical porous structure and superior electrochemical performance after freeze‐drying and annealing treatments. Furthermore, a quasi‐solid‐state symmetric supercapacitor assembled with two interdigitated carbon blocks obtained by a 3D printing technique combined with a nitrogen‐doping strategy delivers an energy density of 0.10 mWh cm−2 at 0.56 mW cm−2. This work provides guidance for the formulation of the printable ink used for 3D printing of high‐performance thick carbon electrodes.
A 3D printable CMU ink consisting of CNFs, MWCNTs, and urea is successfully developed by rational tailoring the concentration‐dependent rheological performance of inks and optimization of the 3D printing parameters. The N‐doped, hierarchically porous, thick carbon architectures can be achieved by 3D printing, freeze‐drying, and annealing approach, which hold the great potential in customized electrochemical energy storage device.
Microplastics (MPs) are a type of contaminants produced during the use and disposal of plastic products, which are ubiquitous in our lives. With the high specific surface area and strong ...hydrophobicity, MPs can adsorb various hazardous microorganisms and chemical contaminants from the environment, causing irreversible damage to our humans. It is reported that the MPs have been detected in infant feces and human blood. Therefore, the presence of MPs has posed a significant threat to human health. It is critically essential to develop efficient, scalable and environmentally-friendly methods to remove MPs. Herein, recent advances in the MPs remediation technologies in water and wastewater treatment processes are overviewed. Several approaches, including membrane filtration, adsorption, chemically induced coagulation-flocculation-sedimentation, bioremediation, and advanced oxidation processes are systematically documented. The characteristics, mechanisms, advantages, and disadvantages of these methods are well discussed and highlighted. Finally, the current challenges and future trends of these methods are proposed, with the aim of facilitating the remediation of MPs in water and wastewater treatment processes in a more efficient, scalable, and environmentally-friendly way.
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•Reviewing the filtration, absorption, coagulation, bioremediation and AOP methods•Discussing the analytical methods for the evaluation of MPs removal efficiency•Proposing the mechanism, advantage and crucial challenge of MPs removal technology•Forecasting the future development trend of MPs removal technology
The aqueous zinc‐ion battery is promising as grid scale energy storage device, but hindered by the instable electrode/electrolyte interface. Herein, we report the lean‐water ionic liquid electrolyte ...for aqueous zinc metal batteries. The lean‐water ionic liquid electrolyte creates the hydrophobic tri‐layer interface assembled by first two layers of hydrophobic OTF− and EMIM+ and third layer of loosely attached water, beyond the classical Gouy–Chapman–Stern theory based electrochemical double layer. By taking advantage of the hydrophobic tri‐layer interface, the lean‐water ionic liquid electrolyte enables a wide electrochemical working window (2.93 V) with relatively high zinc ion conductivity (17.3 mS/cm). Furthermore, the anion crowding interface facilitates the OTF− decomposition chemistry to create the mechanically graded solid electrolyte interface layer to simultaneously suppress the dendrite formation and maintain the mechanical stability. In this way, the lean‐water based ionic liquid electrolyte realizes the ultralong cyclability of over 10000 cycles at 20 A/g and at practical condition of N/P ratio of 1.5, the cumulated areal capacity reach 1.8 Ah/cm2, which outperforms the state‐of‐the‐art zinc metal battery performance. Our work highlights the importance of the stable electrode/electrolyte interface stability, which would be practical for building high energy grid scale zinc‐ion battery.
An electrochemical hydrophobic tri‐layer interface is developed through the lean‐water ionic liquid electrolyte design to create stable electrode/electrolyte interface. The OTF‐ rich interface facilitates the formation of mechanically graded solid electrolyte interface. As a result, the lean‐water ionic liquid electrolyte enabled zinc metal battery stable operation at practical condition and under wide temperature range.
C‐type cytochromes located on the outer membrane (OMCs) of genus Shewanella act as the main redox‐active species to mediate extracellular electron transfer (EET) from the inside of the outer membrane ...to the external environment: the central challenge that must be met for successful EET. The redox states of OMCs play a crucial role in dictating the rate and extent of EET. Here, we report that the surface wettability of the electrodes strongly influences the EET activity of living organisms of Shewanella loihica PV‐4 at a fixed external potential: the EET activity on a hydrophilic electrode is more than five times higher than that on a hydrophobic one. We propose that the redox state of OMCs varies significantly at electrodes with different wettability, resulting in different EET activities.
Hydrophobic or hydrophilic: The electron flow from living microbes can be simply regulated by altering the surface wettability of the electrodes at a fixed external potential. The extracellular electron transfer activity on a hydrophilic electrode is shown to be more than five times higher than that on a hydrophobic one. TCA=tricarboxylic acid.
•Microwave-assisted DES pretreatment is employed for delignification of ECB in 30 min.•Subsequent ultrasonication produces LCNFs with highly entangled network.•Films with LCNFs showed improved ...mechanical and UV-resistance properties.
Lignin-containing cellulose nanofibers (LCNFs) from energy cane bagasse (ECB), were prepared using microwave assisted deep eutectic solvent (MV-DES) treatment in combination with ultrasonication. The yield of lignocellulose is up to 45.2 % with 81.0 % delignification under the optimal reaction condition (110 ℃, 30 min). The resulting LCNF exhibited a highly entangled network, which was caused by the binder role of lignin between cellulose nanofibers. The addition of LCNFs improved the stability of the polyanionic cellulose (PAC) film-forming suspension, which was confirmed by the increased zeta potential and viscosity values. The LCNF / PAC films showed tunable mechanical and UV-resistant properties, depending on the amount and type of LCNFs. PAC films with the addition of 5 % LCNFs (PEF-5 %) showed good mechanical properties (a tensile strength of 55.8 MPa with a 26.3 % strain to break) and high UV protection ability (a UV-transmittance of 2.9 %).
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