Separators play a pivotal role in the electrochemical performance and safety of lithium‐ion batteries (LIBs). The commercial microporous polyolefin‐based separators often suffer from inferior ...electrolyte wettability, low thermal stability, and severe safety concerns. Herein, a novel kind of highly flexible and porous separator based on hydroxyapatite nanowires (HAP NWs) with excellent thermal stability, fire resistance, and superior electrolyte wettability is reported. A hierarchical cross‐linked network structure forms between HAP NWs and cellulose fibers (CFs) via hybridization, which endows the separator with high flexibility and robust mechanical strength. The high thermal stability of HAP NW networks enables the separator to preserve its structural integrity at temperatures as high as 700 °C, and the fire‐resistant property of HAP NWs ensures high safety of the battery. In particular, benefiting from its unique composition and highly porous structure, the as‐prepared HAP/CF separator exhibits near zero contact angle with the liquid electrolyte and high electrolyte uptake of 253%, indicating superior electrolyte wettability compared with the commercial polyolefin separator. The as‐prepared HAP/CF separator has unique advantages of superior electrolyte wettability, mechanical robustness, high thermal stability, and fire resistance, thus, is promising as a new kind of separator for advanced LIBs with enhanced performance and high safety.
A new kind of highly flexible, porous, high‐wettability, fire‐resistant hydroxyapatite nanowire‐based separator with superior performance and high safety is prepared for advanced lithium‐ion batteries. The batteries with the hydroxyapatite nanowire‐based separators show better cyclability and enhanced rate capability compared with those with the commercial polypropylene separator. The as‐prepared batteries adopting the hydroxyapatite nanowire‐based separator can safely work at 150 °C.
•This paper reviews the state of the art of wind energy conversion systems.•Different types of common wind energy conversion systems are classified and compared.•The four most popular MPPT control ...methods are reviewed and compared.•The latest development of wind energy conversion technologies is introduced.•Future trends of the wind energy conversion technologies are discussed.
This paper gives a comprehensive review of the state of the art of wind energy conversion systems (WECS) and technologies, with an emphasis on wind power generator and control. First, different types of common WECSs are classified according to their features and drive train types. The WECSs are compared on the basis of the volume, weight, cost, efficiency, system reliability and fault ride through capability. The maximum power point tracking (MPPT) control, which aims to make the generator speed meet an optimum value to ensure the maximum energy yield, plays a key role in the variable speed WECSs. A comprehensive review and comparison of the four most popular MPPT control methods are carried out and improvements for each method are presented. Furthermore, the latest development of wind energy conversion technologies is introduced, such as the brushless doubly fed induction generator (BDFIG), the stator permanent magnet synchronous generators, the magnetic-geared generators, dual power flow WECS with the electrical variable transmission (EVT) machine, and direct grid-connected WECS. Finally, the future trends of the technologies are discussed.
Microvesicles (MVs) derived from human mesenchymal stem cells (MSC MVs) were demonstrated to ameliorate inflammation in lungs. We have found their content of mRNA for keratinocyte growth factor was ...partly involved in their therapeutic effects. As MSC MVs also contained a substantial quantity of angiopoietin-1 (Ang-1) mRNA, which plays an essential role in vascular stabilization and resolving inflammation, we hypothesized that Ang-1 mRNA might similarly account for a part of their therapeutic effects. We downregulated Ang-1 mRNA expression in MVs, using a lentivirus vector carrying Ang-1 short hairpin RNA to transfect MSCs. A mouse model of lipopolysaccharide induced acute lung injury (ALI) was used in vivo. We also studied in vitro interactions between Ang-1 mRNA deficient MVs on macrophages and human lung microvascular endothelial cells. Compared with negative control, Ang-1 mRNA deficient MVs increased the influx of neutrophils and macrophage inflammatory protein-2 levels in bronchoalveolar lavage fluid by 136% and 105%, respectively, suggesting a deteriorative lung inflammation and a failure to restore pulmonary capillary permeability assessed by Evan's blue dye and bronchoalveolar lavage albumin level. In vitro, the addition of Ang-1 mRNA deficient MVs failed to maintain the integrity of endotoxin-stimulated microvascular endothelial cells and abrogated the decrease in tumor necrosis factor-α level and the increase in interleukin-10 level mediated by negative control in RAW 264.7 cells. In summary, the therapeutic effects of MVs in ALI, and their immunomodulatory properties on macrophages were partly mediated through their content of Ang-1 mRNA. Stem Cells 2017;35:1849-1859.
Practical applications of nanostructured materials have been largely limited by the difficulties in controllable and scaled-up synthesis, large-sized highly ordered self-assembly, and macroscopic ...processing of nanostructures. Hydroxyapatite (HAP), the major inorganic component of human bone and tooth, is an important biomaterial with high biocompatibility, bioactivity, and high thermal stability. Large-sized highly ordered HAP nanostructures are of great significance for applications in various fields and for understanding the formation mechanisms of bone and tooth. However, the synthesis of large-sized highly ordered HAP nanostructures remains a great challenge, especially for the preparation of large-sized highly ordered ultralong HAP nanowires because ultralong HAP nanowires are easily tangled and aggregated. Herein, we report our three main research findings: (1) the large-scale synthesis of highly flexible ultralong HAP nanowires with lengths up to >100 μm and aspect ratios up to >10000; (2) the demonstration of a strategy for the rapid automated production of highly flexible, fire-resistant, large-sized, self-assembled highly ordered ultralong HAP nanowires (SHOUHNs) at room temperature; and (3) the successful construction of various flexible fire-resistant HAP ordered architectures using the SHOUHNs, such as high-strength highly flexible nanostructured ropes (nanoropes), highly flexible textiles, and 3-D printed well-defined highly ordered patterns. The SHOUHNs are successively formed from the nanoscale to the microscale then to the macroscale, and the ordering direction of the ordered HAP structure is controllable. These ordered HAP architectures made from the SHOUHNs, such as highly flexible textiles, may be engineered into advanced functional products for applications in various fields, for example, fireproof clothing.
With the growing popularity of electrical communication equipment, high-performance electromagnetic interference (EMI) shielding materials are widely used to deal with radiation pollution. However, ...the large thickness and poor mechanical properties of many EMI shielding materials usually limit their applications. In this study, ultrathin and highly flexible Ti3C2T x (d-Ti3C2T x , MXene)/cellulose nanofiber (CNF) composite paper with a nacre-like lamellar structure is fabricated via a vacuum-filtration-induced self-assembly process. By the interaction between one-dimensional (1D) CNFs and two-dimensional (2D) d-Ti3C2T x MXene, the binary strengthening and toughening of the nacre-like d-Ti3C2T x /CNF composite paper has been successfully achieved, leading to high tensile strength (up to 135.4 MPa) and fracture strain (up to 16.7%), as well as excellent folding endurance (up to 14 260 times). Moreover, the d-Ti3C2T x /CNF composite paper exhibits high electrical conductivity (up to 739.4 S m–1) and excellent specific EMI shielding efficiency (up to 2647 dB cm2 g–1) at an ultrathin thickness (minimum thickness 47 μm). The nacre-inspired strategy in this study offers a promising approach for the design and preparation of the strong integrated and flexible MXene/CNF composite paper, which may be applied in various fields such as flexible wearable devices, weapon equipment, and robot joints.
Plasmonic color filtering and color printing have attracted considerable attention in recent years due to their supreme performance in display and imaging technologies. Although various color‐related ...devices are designed, so far very few studies have touched the topic of dynamic color generation. In this article, dynamic color generation is demonstrated by integrating plasmonic nanostructures with vanadium dioxide based on its tunable optical properties through insulator–metal transition. Periodic arrays of silver nanodisks on a vanadium dioxide film are fabricated to realize different colors, relying on the excitation of localized and propagating surface plasmons, and Wood's anomaly. By tuning spatial periodicity of the arrays and diameter of the silver nanodisks, various colors can be achieved across the entire visible spectrum. Further, using insulator–metal transition of vanadium dioxide, the colors can be actively tuned by varying temperature. The approach of dynamic color generation based on the phase transition of vanadium dioxide can easily realize diverse color patterns, which makes it beneficial for display and imaging technology with distinct advantages of multifunctionality, flexibility, and high efficiency.
Dynamic color generation is realized by integrating plasmonic nanostructures with vanadium dioxide based on its tunable optical properties through insulator–metal transition. Various colors can be designed across the visible spectrum via adjusting the spatial periodicity and nanodisk diameter of the silver‐nanodisk array, and the colors can be tuned dynamically by varying the temperature.
Solar energy‐driven water evaporation is a promising sustainable strategy to purify seawater and contaminated water. However, developing solar evaporators with high water evaporation rates and ...excellent salt resistance still faces a great challenge. Herein, inspired by the long‐range ordered structure and water transportation capability of lotus stem, a biomimetic aerogel with vertically ordered channels and low water evaporation enthalpy for high‐efficiency solar energy‐driven salt‐resistant seawater desalination and wastewater purification is developed. The biomimetic aerogel consists of ultralong hydroxyapatite nanowires as heat‐insulating skeletons, polydopamine‐modified MXene as a photothermal material with broadband sunlight absorption and high photothermal conversion efficiency, polyacrylamide, and polyvinyl alcohol as reagents to lower the water evaporation enthalpy and as glues to enhance the mechanical performance. The honeycomb porous structure, unidirectionally aligned microchannels, and nanowire/nanosheet/polymer pore wall endow the biomimetic aerogel with excellent mechanical properties, rapid water transportation, and excellent solar water evaporation performance. The biomimetic aerogel exhibits a high water evaporation rate (2.62 kg m−2 h−1) and energy efficiency (93.6%) under one sun irradiation. The superior salt‐rejecting ability of the designed water evaporator enables stable and continuous seawater desalination, which is promising for application in water purification to mitigate the global water crisis.
A lotus stem‐inspired aerogel water evaporator with vertically aligned channels and low water evaporation enthalpy is fabricated using ultralong hydroxyapatite nanowires, polyacrylamide, polyvinyl alcohol, and polydopamine‐modified MXene, which exhibits a high water evaporation rate and high energy efficiency as well as stable and salt‐rejecting seawater desalination.
Water pollution and freshwater shortage have deteriorated the global water crisis. Developing sustainable methods to alleviate contaminated water has become an urgent affair. Herein, inspired by ...water transportation and transpiration of natural trees, the authors report an ultralong hydroxyapatite nanowires‐based biomimetic aerogel with vertically aligned channels and multiple functions for continuous flow catalysis, water disinfection, solar energy‐driven water purification, and seawater desalination. Ultralong hydroxyapatite nanowires act as carriers to immobilize catalyst nanoparticles and serve as building blocks to assemble with chitosan to form the biomimetic aerogel with structure‐function integration. Benefiting from the interconnected cellular structure, unidirectional aligned channels, nanowire‐interwoven networked pore wall, and evenly distributed catalyst nanoparticles, the biomimetic aerogel exhibits high catalytic activity (97.6% treatment efficiency) and permeability (1786 L m−2 h−1), excellent recyclability and stability in continuous flow catalytic degradation of methylene blue solely driven by gravity. The biomimetic aerogel exhibits excellent performance for bacteria removal and anti‐biofouling. The superior photothermal conversion and heat confinement properties enable the biomimetic aerogel with a high efficiency (86.7%) for solar energy‐driven seawater desalination and wastewater purification under one sun irradiation. The multifunctional biomimetic aerogel has promising applications in catalytic reactions, wastewater remediation, and environmental engineering.
A tree‐inspired multifunctional aerogel with vertically aligned channels is fabricated from ultralong hydroxyapatite nanowires, immobilized palladium nanoparticles, and chitosan through a unidirectional freeze‐drying approach. The biomimetic aerogel exhibits high performances in gravity‐driven continuous flow catalytic reactions, water disinfection, and solar energy‐driven water purification and seawater desalination.
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