Supercapacitors attract great interest because of the increasing and urgent demand for environment‐friendly high‐power energy sources. Ti3C2, a member of MXene family, is a promising electrode ...material for supercapacitors owing to its excellent chemical and physical properties. However, the highest gravimetric capacitance of the MXene‐based electrodes is still relatively low (245 F g−1) and the key challenge to improve this is to exploit more pseudocapacitance by increasing the active site concentration. Here, a method to significantly improve the gravimetric capacitance of Ti3C2Tx MXenes by cation intercalation and surface modification is reported. After K+ intercalation and terminal groups (OH−/F−) removing , the intercalation pseudocapacitance is three times higher than the pristine MXene, and MXene sheets exhibit a significant enhancement (about 211% of the origin) in the gravimetric capacitance (517 F g−1 at a discharge rate of 1 A g−1). Moreover, the as‐prepared electrodes show above 99% retention over 10 000 cycles. This improved electrochemical performance is attributed to the large interlayer voids of Ti3C2 and lowest terminated surface group concentration. This study demonstrates a new strategy applicable to other MXenes (Ti2CTx, Nb2CTx, etc.) in maximizing their potential applications in energy storage.
Cation intercalation and surface modification are new strategies in maximizing the potential applications of MXene in energy storage. After K+ intercalation and terminal groups (OH−/F−) removing, the intercalation‐pseudocapacitance of Ti3C2 MXene is three times higher than pristine MXene and exhibits a significant enhancement in the gravimetric capacitance and energy density. The as‐prepared electrodes show above 99% retention over 10 000 cycles.
Water splitting requires development of cost‐effective multifunctional materials that can catalyze both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) efficiently. ...Currently, the OER relies on the noble‐metal catalysts; since with other catalysts, its operation environment is greatly limited in alkaline conditions. Herein, an advanced water oxidation catalyst based on metallic Co9S8 decorated with single‐atomic Mo (0.99 wt%) is synthesized (Mo‐Co9S8@C). It exhibits pronounced water oxidization activity in acid, alkali, and neutral media by showing positive onset potentials of 200, 90, and 290 mV, respectively, which manifests the best Co9S8‐based single‐atom Mo catalyst till now. Moreover, it also demonstrates excellent HER performance over a wide pH range. Consequently, the catalyst even outperforms noble metal Pt/IrO2‐based catalysts for overall water splitting (only requiring 1.68 V in acid, and 1.56 V in alkaline). Impressively, it works under a current density of 10 mA cm−2 with no obvious decay during a 24 h (0.5 m H2SO4) and 72 h (1.0 m KOH) durability experiment. Density functional theory (DFT) simulations reveal that the synergistic effects of atomically dispersed Mo with Co‐containing substrates can efficiently alter the binding energies of adsorbed intermediate species and decrease the overpotentials of the water splitting.
Novel precious‐metal free Mo single‐atom bifunctional catalysts can catalyse the oxygen evolution reaction, hydrogen evolution reaction, and overall water splitting reactions in pH‐universal conditions. Furthermore, the reported Mo‐Co9S8@C sample exhibits the best durability for a given activity over a wide pH range (acid, base, and neutral) among all reported catalysts. Consequently, the bifunctional Mo‐Co9S8@C catalyst outperforms noble metal Pt/IrO2‐based catalysts for overall water splitting.
The primary goal of the present study was to develop the nano-drug consisting of doxorubicin and exosome derived from mesenchymal stem cells, and to explore its effect on osteosarcoma in vitro.
The ...exosomes were isolated from bone marrow MSCs (BM-MSCs) by an Exosome Isolation Kit. The exosome-loaded doxorubicin (Exo-Dox) was prepared by mixing exosome with Dox-HCl, desalinizing with triethylamine and then dialyzing against PBS overnight. The nanoparticle tracking analysis (NTA) and transmission electron microscope (TEM) were used to characterize of the exosome and Exo-Dox. The cytotoxicity of Exo-Dox was determined by CCK-8 assay. Further, the cellular uptake of different drugs was analyzed using inverted fluorescence microscope and flow cytometry.
The typical exosome structures can be observed by TEM. After loading with doxorubicin, its size is larger than free exosome. Compared with the free Dox, the prepared Exo-Dox showed enhanced cellular uptake efficiency and anti-tumor effect in osteosarcoma MG63 cell line but low cytotoxicity in myocardial H9C2 cell line.
The prepared Exo-Dox could be used as an excellent chemotherapeutic drug for treatment of osteosarcoma in vitro. Considering the tumor-homing feature of BM-MSCs, the Exo-Dox may be a good candidate for targeted osteosarcoma treatment in future study.
A novel architecture of 3D graphene growth on porous Al2O3 ceramics is proposed for thermal management using ambient pressure chemical vapor deposition. The formation mechanism of graphene is ...attributed to the carbothermic reduction occurring at the Al2O3 surface to initialize the nucleation and growth of graphene. The graphene films are coated on insulating anodic aluminum oxide (AAO) templates and porous Al2O3 ceramic substrates. The graphene coated AAO possesses one‐dimensional isolated graphene tubes, which can act as the media for directional thermal transport. The graphene/Al2O3 composite (G‐Al2O3) contains an interconnected macroporous graphene framework with an extremely low sheet electrical resistance down to 0.11 Ω sq−1 and thermal conductivity with 8.28 W m−1 K−1. The G‐Al2O3 provides enormous conductive pathways for electronic and heat transfer, suitable for application as heat sinks. Such a porous composite is also attractive as a highly thermally conductive reservoir to hold phase change materials (stearic acid) for thermal energy storage. This work displays the great potential of CVD direct growth of graphene on dielectric porous substrates for thermal conduction and electronic applications.
A novel architecture of 3D graphene is proposed by direct growth on porous Al2O3 ceramics by using chemical vapor deposition. The graphene/Al2O3 composite provides enormous conductive pathways for electron and phonon transport, suitable for application as a heat sink. Furthermore, the composite acts as a new type of highly thermally conductive reservoir to accommodate phase change materials for thermal energy storage.
The possibility of superconductivity in tetragonal FeS has attracted considerable interest because of its similarities to the FeSe superconductor. However, all efforts made to pursue ...superconductivity in tetragonal FeS have failed so far, and it remains controversial whether tetragonal FeS is metallic or semiconducting. Here we report the observation of superconductivity at 5 K in tetragonal FeS that is synthesized by the hydrothermal reaction of iron powder with sulfide solution. The obtained samples are highly crystalline and less air-sensitive, in contrast to those reported in the literature, which are meta-stable and air-sensitive. Magnetic and electrical properties measurements show that the samples behave as a paramagnetic metal in the normal state and exhibit superconductivity below 5 K. The high crystallinity and the stoichiometry of the samples play important roles in the observation of superconductivity. The present results demonstrate that tetragonal FeS is a promising new platform to realize high-temperature superconductors.
Modification of rutile titanium dioxide (TiO2) for hydrogen generation and water cleaning is a grand challenge due to the chemical inertness of rutile, while such inertness is a desired merit for its ...stability in photoelectrochemical applications. Herein, we report an innovative two-step method to prepare a core–shell nanostructured S-doped rutile TiO2 (R′-TiO2-S). This modified black rutile TiO2 sample exhibits remarkably enhanced absorption in visible and near-infrared regions and efficient charge separation and transport. As a result, the unique sulfide surface (TiO2–x :S) boosts the photocatalytic water cleaning and water splitting with a steady solar hydrogen production rate of 0.258 mmol h–1 g–1. The black titania is also an excellent photoelectrochemical electrode exhibiting a high solar-to-hydrogen conversion efficiency of 1.67%. The sulfided surface shell is proved to be an effective strategy for enhancing solar light absorption and photoelectric conversion.
Organic phase change materials are usually insulating in nature, and they are unlikely to directly trigger latent heat storage through an electrical way. Here we report a multifunctional phase change ...composite in which the energy storage can be driven by small voltages (e.g., 1.5 V) or light illumination with high electro-to-heat or photo-to-thermal storage efficiencies (40% to 60%). The composite is composed of paraffin wax infiltrated into a porous, deformable carbon nanotube sponge; the latter not only acts as a flexible encapsulation scaffold for wax but also maintains a highly conductive network during the phase change process (for both solid and liquid states). Uniform interpenetration between the nanotube network and paraffin wax with high affinity results in enhanced phase change enthalpy and thermal conductivity compared to pure paraffin wax. Our phase change composite can store energy in practical ways such as by sunlight absorption or under voltages applied by conventional lithium-ion batteries.
This paper investigates one of the key decision-making problems referring to the integrated production planning (IPP) for the steelmaking continuous casting-hot rolling (SCC-HR) process in the steel ...industry. The complexities of the practical IPP problem are mainly reflected in three aspects: large-scale decision variables; multiple objectives and interval-valued uncertain parameters. To deal with the difficulty of large-scale decision variables, we introduce a new concept named “order-set” for modeling. In addition, considering the multiple objectives and uncertainties of the given IPP problem, we construct a multi-objective optimization model with interval-valued objective functions to optimize the throughput of each process, the hot charge ratio of slabs, the utilization rate of tundishes and the additional cost of technical operations. Furthermore, we propose a novel approach based on a modified interval multi-objective optimization evolutionary algorithm (MI-MOEA) to solve the problem. The proposed model and algorithm were tested with daily production data from an iron and steel company in China. Computational experiments demonstrate that the proposed method generates quite effective and practical solutions within a short time. Based on the IPP model and MI-MOEA, an IPP system has been developed and implemented in the company.
•An integrated production planning problem in steel industry is investigated.•A new concept of “order-set” is introduced to reduce the size of the problem.•Multi-objective optimization model with interval-valued uncertain parameters.•Modified interval multi-objective optimization evolutionary algorithm.•The proposed method generates effective and practical solutions in a short time.
Lipopolysaccharide (LPS) and Receptor Activator of Nuclear Factor-κB Ligand (RANKL) are the two important factors causing bone loss, which is an important pathogenesis for osteoporosis. However, the ...relationship between LPS and RANKL is not yet clear. LPS can be involved in the weakened osteoblast formation as an autophagy regulator, and osteoblasts and their precursors are the source cells for RANKL production. Our study aimed to explore the relationship between autophagy changes and RANKL production during LPS-regulated osteoblasts. Our results showed that LPS inhibited autophagy (LC3 conversion and autophagosome formation) and enhanced the protein and mRNA expression of RANKL in MC3T3-E1 osteoblast precursor line. Autophagy upregulation with Rapamycin over BECN1 overexpression rescued LPS-inhibited osteoblast formation and -promoted RANKL protein production in MC3T3-E1 cells. In vivo experiments supported that damaged bone mass, bone microstructure, osteoblastic activity (ALP and P1NP production by ELISA assays) and enhanced RANKL production by LPS administration were partially rescued by Rapamycin application. In conclusion, LPS can inhibit autophagy in osteoblast precursors, thereby inhibiting osteoblast formation and RANKL autophagic degradation.
We report a carbon nanotube array-encapsulated phase change composite in which the nanotube distribution (or areal density) could be tailored by uniaxial compression. The n-eicosane (C20) was ...infiltrated into the porous array to make a highly conductive nanocomposite while maintaining the nanotube dispersion and connection among the matrix with controlled nanotube areal density determined by the compressive strains along the lateral direction. The resulting electrically conductive composites can store heat at driven voltages as low as 1 V at fast speed with high electro-to-heat conversion efficiencies. Increasing the nanotube density is shown to significantly improve the polymer crystallinity and reduce the voltage for inducing the phase change process. Our results indicate that well-organized nanostructures such as the nanotube array are promising candidates to build high-performance phase change composites with simplified manufacturing process and modulated structure and properties.
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