One-Pot Etching Pyrolysis to Defect-Rich Carbon Nanosheets to Construct Multiheteroatom-Coordinated Iron Sites for Efficient Oxygen Reduction.

Constructing multiheteroatom coordination structure in carbonaceous substrates demonstrates an effective method to accelerate the oxygen reduction reaction (ORR) of supported single-atom catalyst. Herein, the novel etching route assisted by potassium thiocyanate (KCNS) is developed to convert metal-organic framework to 2D defect-rich porous N,S-co-doped carbon nanosheets for anchoring atomically dispersed iron sites as the high-performance ORR catalysts (Fe-SACs). The well-designed KCNS-assisted etching route can generate spatial confinement template to direct the carbon nanosheet formation, etching condition to form defect-rich structure, and additional sulfur atoms to coordinate iron species. Spectral and microscopy analysis reveals that the iron element in Fe-SACs is highly isolated on carbon nanosheet and anchored by nitrogen and sulfur atoms in unsymmetrical Fe-S1N3 structure. The optimized Fe-SACs with large specific surface area could show remarkable alkaline ORR performances with a high half-wave potential of 0.920 V versus RHE and excellent durability. The rechargeable zinc-air battery assembled with Fe-SACs air electrodes delivers a large power density of 350 mW cm-2 and a stable voltage platform during charge and discharge over more than 1300 h. This work proposes a novel strategy for the preparation of single-atom catalysts with multiheteroatom coordination structure and highly exposed active sites for efficient ORR.

A sodium alginate/carboxymethyl chitosan dual-crosslinked injectable hydrogel scaffold with tunable softness/hardness for bone regeneration.

Recently, injectable dual-crosslinked (DC) hydrogel scaffolds have attracted many attentions as a class of excellent bone regeneration biomaterials with in-situ tunable functions. However, the design of injectable DC hydrogels with cell behavior-compatible network structure and mechanical property remains a bottleneck. Herein, based on the in-situ gelling method, we constructed an injectable CMCS/PEG+SA/CaCl2 (CPSC) chemical/physical DC hydrogel scaffold with tunable softness/hardness mechanical properties and good biocompatibility. The formation mechanism and properties of the CPSC hydrogel scaffold were investigated by FTIR, XRD, rheometry, and mechanical testing. It is found that proper softness/hardness mechanical properties can be obtained by adjusting the secondary network structure of the hydrogel. The CPSC hydrogel scaffold prepared under optimal conditions can effectively promote cell infiltration, nutrient transport, and the osteogenic differentiation of rat bone mesenchymal stem cells (rBMSCs). The in vivo experiments show that the rBMSCs-loaded injectable CPSC hydrogels with appropriate mechanical properties can effectively promote bone reconstruction. This study has provided important guidance for the construction of injectable DC hydrogels with adjustable softness/hardness to promote osteogenesis for bone defect repair.

A natural polymer-based hydrogel with shape controllability and high toughness and its application to efficient osteochondral regeneration.

Hydrogels prepared from sustainable natural polymers have broad prospects in the biological field. However, their poor mechanical properties and challenges in achieving shape control have limited their application. Herein, a novel preforming dual-effect post-enhancing method is proposed to address these issues. The method utilizes the hydrogen bonding of agar to obtain a shape-controllable preformed hydrogel at low polymer concentrations using casting, injection, or 3D printing techniques. Subsequently, the preformed hydrogel was subjected to a permeation process to form a post-enhanced multi-network (PEMN) hydrogel with hierarchical chain entanglements to ensure its high toughness, which exhibits tensile and compressive strengths of up to 0.51 MPa and 1.26 MPa with solely physically crosslinking networks. The excellent biocompatibility of the PEMN hydrogel prepared without the need for additional initiator agents under mild conditions was confirmed by both in vitro and in vivo experiments. Furthermore, the adaptability for irregular defects, suitable toughness, adhesive properties, and degradability of PEMN hydrogels are beneficial to provide mechanical support, induce endogenous cell mineralization, and accelerate the regeneration of cartilage and subchondral bone with more than 40% bone regeneration in 12 weeks. Our work has provided a novel solution to simultaneously achieve shape controllability and high toughness based on natural polymers among the already well-explored strategies for osteochondral regeneration.

Tuning Carbon Defect in Copper Single-Atom Catalysts for Efficient Oxygen Reduction.

Defect chemistry in carbon matrix shows great potential for promoting the oxygen reduction reaction (ORR) of metal single-atom catalysts. Herein, a modified pyrolysis strategy is proposed to tune carbon defects in copper single-atom catalysts (Cu-SACs) to fully understand their positive effect on the ORR activity. The optimized Cu-SACs with controllable carbon defect degree and enhanced active specific surface area can exhibit improved ORR activity with a half-wave potential of 0.897 VRHE , ultrahigh limiting current density of 6.5 mA cm-2 , and superior turnover frequency of 2.23 e site-1 s-1 . The assembled Zn-air batteries based on Cu-SACs can also show well-retained reversibility and voltage platform over 1100 h charge/discharge period. Density functional theory calculations reveal that suitable carbon defects can redistribute charge density of Cu-N4 active sites to weaken the O-O bond in adsorbed OOH* intermediate and thus reduce its dissociation energy. This discovery offers a universal strategy for fabricating superior single-atom catalysts with high-efficiency active sites toward energy-directed applications.

A facile and simple microwave-assisted synthesis method for mesoporous ultrathin iron sulfide nanosheets as an efficient bifunctional electrocatalyst for overall water splitting.

The engineering of inexpensive, high-efficiency and stable electrodes related to both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is highly desired for full water splitting devices to promote future advances in this energy technology. Therefore, a large surface area, rich in exposed surface atoms, and mesoporosity are very effective parameters in electrochemical reactions. Herein, we have, for the first time, synthesized free-standing mesoporous Fe3S4 nanosheets with a large surface area of 129.65 m2 g-1 through a microwave-assisted synthetic technique. Our present synthesis strategy demonstrates a facile and cost-effective method to overcome the obstacles of fabricating ultrathin two-dimensional graphene-like transition metal sulfide nanosheets. The as-synthesized Fe3S4 nanosheets are applied as both cathodic and anodic electrodes for full water electrolysis. Remarkably, Fe3S4 nanosheets can exhibit a small overpotential (η = 103 mV) to provide the required 10 mA cm-2 current density during the HER process. Meanwhile, a low overpotential of 230 mV is also exhibited for the OER process to allow a 10 mA cm-2 current density. Furthermore, the assembled full water splitting device can achieve potentials of 1.43 and 1.65 V at 10 and 100 mA cm-2 current densities, respectively, in an alkaline electrolyte with excellent cycling stability over 24 h. Our current study may provide an advanced channel for transition metal sulfide catalysts towards commercial water splitting applications.

Anionic Te-Substitution Boosting the Reversible Redox in CuS Nanosheet Cathodes for Magnesium Storage.

The conversion-type copper chalcogenide cathode materials hold great promise for realizing the competitive advantages of rechargeable magnesium batteries among next-generation energy storage technologies; yet, they suffer from sluggish kinetics and low redox reversibility due to large Coulombic resistance and ionic polarization of Mg2+ ions. Here we present an anionic Te-substitution strategy to promote the reversible Cu0/Cu+ redox reaction in Te-substituted CuS1-xTex nanosheet cathodes. X-ray absorption fine structure analysis demonstrates that Te dopants occupy the anionic sites of sulfur atoms and result in an improved oxidation state of the Cu species. The kinetically favored CuS1-xTex (x = 0.04) nanosheets deliver a specific capacity of 446 mAh g-1 under a 20 mA g-1 current density and a good long-life cycling stability upon 1500 repeated cycles with a capacity decay rate of 0.0345% per cycle at 1 A g-1. Furthermore, the CuS1-xTex (x = 0.04) nanosheets can also exhibit an enhanced rate capability with a reversible specific capacity of 100 mAh g-1 even under a high current density of 1 A g-1. All the obtained electrochemical characteristics of CuS1-xTex nanosheets significantly exceed those of pristine CuS nanosheets, which can contribute to the improved redox reversibility and favorable kinetics of CuS1-xTex nanosheets. Therefore, anionic Te-substitution demonstrates a route for purposeful cathode chemistry regulation in rechargeable magnesium batteries.

General metal-organic framework-derived strategy to synthesize yolk-shell carbon-encapsulated nickelic spheres for sodium-ion batteries.

Transition-metal compounds have attracted enormous attention as potential energy storage materials for their high theoretical capacity and energy density. However, the most present transition-metal compounds still suffer from severe capacity decay and limited rate capability due to the lack of robust architectures. Herein, a general metal-organic framework-derived route is reported to fabricate hierarchical carbon-encapsulated yolk-shell nickelic spheres as anode materials for sodium-ion batteries. The nickelic metal-organic framework (Ni-MOF) precursors can be in situ converted into hierarchical carbon-encapsulated Ni2P (Ni2P/C), NiS2 (NiS2/C) and NiSe2 (NiSe2/C) by phosphorization, sulfuration, and selenation reaction, respectively, and maintain their yolk-shell sphere-like morphology. The as-synthesized Ni2P/C sample can deliver much lower polarization and discharge platform, smaller voltage gap, and faster kinetics in comparison with that of the other two counterparts, and thus achieve higher initial specific capacity (3222.1/1979.3 mAh g-1) and reversible capacity of 765.4 mAh g-1 after 110 cycles. This work should provide new insights into the phase and structure engineering of carbon-encapsulated transition-metal compound electrodes via MOFs template for advanced battery systems.

Facile One-Step Microwave-Assisted Method to Synthesize Nickel Selenide Nanosheets for High-Performance Hybrid Supercapacitor.

Nanosheets structures can be employed as the most promising electrode material to enhance electrochemical performance for supercapacitors. Nickel Selenide (Ni0.85Se) nanosheets are synthesized using a rapid microwave synthesis method in a single step. The Ni0.85Se nanosheets possess a high surface area (125 m2g-1) with a hexagonal crystalline structure. It shows magnificent electrochemical properties, such as splendid specific capacitance (2530 Fg-1 at 0.5 Ag-1). An asymmetric hybrid supercapacitor is fabricated with nickel selenide nanosheets as a positive electrode and activated carbon as a negative electrode. The assembled hybrid supercapacitor displays a high energy density of 63.5 WhKg-1 at a power density of 404 WKg-1, and after 8000 cycles, only 5% capacitance is lost along with the better voltage window at 0-1.6 V.

Cuprous Self-Doping Regulated Mesoporous CuS Nanotube Cathode Materials for Rechargeable Magnesium Batteries.

Copper sulfides are broadly explored as the possible cathode materials for rechargeable magnesium batteries on account of their high theoretical capacity of 560 mAh g-1. However, the CuS cathodes usually suffer from serious capacity decay caused by structure collapse during the repeated magnesiation/demagnesiation process. Herein, we present a cuprous self-doping strategy to synthesize mesoporous CuS nanotubes with robust structural stability for rechargeable magnesium batteries and regulate their electrochemical magnesium storage behavior. Electrochemical results show that the mesoporous CuS nanotubes can exhibit high specific capacity, remarkable cycling performance, and good rate capability. The observed discharge capacity of the mesoporous CuS nanotubes could reach about 281.2 mAh g-1 at 20 mA g-1 and 168.9 mAh g-1 at 500 mA g-1. Furthermore, a remarkable ultralong-term cyclic stability with a reversible capacity of 72.5 mAh g-1 at 1 A g-1 is obtained after 550 cycles. These results demonstrate that the mesoporous nanotube structure and the simple cuprous self-doping effect could promote the practical application of copper sulfide cathode materials for rechargeable magnesium batteries.

Facile synthesis of 3D silk fibroin scaffolds with tunable properties for regenerative medicine.

Silk fibroin (SF) porous scaffolds provide mechanical support and biochemical signals to encourage cell attachment and modify biological performance. The available methods for the preparation of SF scaffolds are still required. The crosslinkers used are likely to impact the biocompatibility. Herein, water-insoluble SF scaffolds were prepared by physical methods. The phosphate solution promoted SF molecules aggregate from SF/heparin mixed solution. Then SF scaffolds were prepared in centrifuge tubes under different centrifugal speed. The phosphate was leached from the scaffolds, leaving porous structure. The centrifugal force produced shear-induced silk crystallinity to tune the mechanical performance like the natural silkworm gland. The relationship between performance and second structure of the scaffolds have been revealed by X-ray Diffraction (XRD) and deconvoluting Fourier Transform Infrared spectroscopy (FTIR). Due to changes in the ß-sheet content, pore structure, mechanical strength, and drug-loaded behavior was adjustable. The scaffolds performed excellent on the Activated Partial Thromboplastin Time (APTT) value, and it can keep sustainable released for 7 days. The scaffolds prepared in mild environment showed tunable stiffness, good anticoagulation, and improved cell compatibility, suggesting its potential application in regenerative medicine.

Cobalt-doping SnS2 nanosheets towards high-performance anodes for sodium ion batteries.

Layered SnS2 is considered as a promising anode candidate for sodium-ion batteries yet suffers from low initial coulombic efficiency, limited specific capacity and rate capability. Herein, we report a cobalt metal cation doping strategy to enhance the electrochemical performance of a SnS2 nanosheet array anode through a facile hydrothermal method. Benefitting from this special structure and heteroatom-doping effect, this anode material displays a high initial coulombic efficiency of 57.4%, a superior discharge specific capacity as high as 1288 mA h g-1 at 0.2 A g-1 after 100 cycles and outstanding long-term cycling stability with a reversible capacity of 800.4 mA h g-1 even at 2 A g-1. These excellent performances could be ascribed to the Co-doping effect that can increase the interlayer spacing, produce rich defects, regulate the electronic environment and improve conductivity. Besides, a carbon cloth substrate can maintain the integrity of the electrode material framework and buffer its volume variation, thus boosting intrinsic dynamic properties and enhancing sodium storage performance.

Anionic Se-Substitution toward High-Performance CuS1- x Sex Nanosheet Cathode for Rechargeable Magnesium Batteries.

Rechargeable magnesium batteries (rMBs) are promising as the most ideal further energy storage systems but lack competent cathode materials due to sluggish redox reaction kinetics. Herein, developed is an anionic Se-substitution strategy to improve the rate capability and the cycling stability of 2D CuS1- x Sex nanosheet cathodes through an efficient microwave-induced heating method. The optimized CuS1- x Sex (X = 0.2) nanosheet cathode can exhibit high reversible capacity of 268.5 mAh g-1 at 20 mA g-1 and good cycling stability (140.4 mAh g-1 at 300 mA g-1 upon 100 cycles). Moreover, the CuS1- x Sex (X = 0.2) nanosheet cathode can deliver remarkable rate capability with a reversible capacity of 119.2 mAh g-1 at 500 mA g-1 , much higher than the 21.7 mAh g-1 of pristine CuS nanosheets. The superior electrochemical performance can be ascribed to the enhanced reaction kinetics, enriched cation storage active sites, and shortened ion diffusion pathway of the CuS1- x Sex nanosheet. Therefore, tuning anionic chemical composition demonstrates an effective strategy to develop novel cathode materials for rMBs.

Mo-Modified P2-type Manganese Oxide Nanoplates with an Oriented Stacking Structure and Exposed {010} Active Facets as a Long-Life Sodium-Ion Battery Cathode.

Layered manganese-based cathode materials are of great interest because of their high specific capacities for sodium-ion batteries. However, the Jahn-Teller effect and the inevitable phase transition are detrimental for achieving considerable cycling stability and rate capability. Herein, a P2-type manganese oxide nanoplate cathode material modified by Mo-substitution with an oriented stacking structure and exposed {010} active facets is reported. The manganese oxide nanoplate cathode yields remarkable capacity retention of 86% after 1200 cycles at 10 C (2000 mA g-1). The specific power density is estimated to be as high as 530 W kg-1 with a specific discharge capacity 143.9 mA h g-1 at 1 C and 89.6% capacity retention up to 100 cycles. The superior electrochemical performances can be attributed to the efficient chemical modification and the unique structural features of the present manganese oxide nanoplate. Mo-modification can endow the manganese oxide cathode with enlarged lattice space and average oxidation state and thus favorable Na+ diffusion to inhibit the Jahn-Teller effect and improve the structure stability, thereby achieving an extremely long cycling life. A multilayer oriented stacking nanoplate structure with exposed {010} active facets is also beneficial for providing more surface active sites and shortening the Na+ diffusion path, leading to better rate capability.

In situ synthesis of poly (γ- glutamic acid)/alginate/AgNP composite microspheres with antibacterial and hemostatic properties.

In the present work, a poly(γ-glutamic acid)/alginate/silver nanoparticle (PGA/Alg/AgNP) composite microsphere with excellent antibacterial and hemostatic properties was prepared by the in situ UV reduction and emulsion internal gelation method, and its potential application for antibacterial hemostatic dressing was explored. Well dispersed AgNPs were in situ synthesized by a UV reduction method with alginate as stabilizer and reductant. The AgNPs showed excellent antibacterial activities against both gram-negative and gram-positive bacteria. Additionally, the AgNPs prepared by the in-situ UV reduction exhibited better biocompatibility and antibacterial effects than those prepared by the conventional chemical reduction method. PGA/Alg/AgNP composite microspheres were then prepared with the AgNPs by an emulsion internal gelation method. Such microspheres were found to be a porous and hollow network with pH-sensitive swelling properties and excellent hemostatic performance, indicating its application potentials as an advanced antibacterial hemostatic material.

The Kiss2/GPR54 system stimulates the reproductive axis in male black porgy, Acanthopagrus schlegelii.

Although it is well established that the Kiss1/GPR54 system stimulates the reproductive axis in mammals, its functional roles, especially in male reproduction of non-mammalian species, is less clear. In this study, we have isolated the full-length kiss2 and gpr54 cDNAs from black porgy (Acanthopagrus schlegelii). The Kiss2 precursor expressed from kiss2 comprises 124 amino acids and contains a highly conserved 10-amino acid sequence, Kiss2-10 (FNFNPFGLRF). GPR54 comprises 375 amino acid residues and contains distinct characteristics of G protein-coupled receptors. Real-time PCR analysis indicated that kiss2 and gpr54 were expressed highly in the brain regions. Moreover, intraperitoneal injection of porgy Kiss2-10 could stimulate genes expression of the gpr54, gnrh1, gnrh3, fshß, lhß, p450c17, star, and ar, and the serum testerone level in male black porgy. Our findings demonstrate that the Kisspeptin stimulates the male reproductive axis in black porgy.

Microwave-Assisted Synthesis of CuS Hierarchical Nanosheets as the Cathode Material for High-Capacity Rechargeable Magnesium Batteries.

Rechargeable magnesium batteries (rMBs) have been recognized as one of most promising next-generation energy storage devices with high energy and power density. However, the development of rMBs has been hampered by the lack of usable cathode materials with high capacity and cycling stability. Herein, we report an ultra-rapid, cost-effective, and scalable synthesis of ultrathin CuS hierarchical nanosheets by a one-step microwave-assisted preparation. Benefiting from the exceptional structural configuration, when used as the cathode material for rMBs at room temperature, the CuS hierarchical nanosheets deliver a high reversible discharge capacity of 300 mA h g-1 at 20 mA g-1, remarkable rate capability (256.5 mA h g-1 at 50 mA g-1 and 237.5 mA h g-1 at 100 mA g-1), and excellent cycling stability (135 mA h g-1 at 200 mA g-1 over 200 cycles). To date, the obtained excellent electrochemical performances are superior to most results ever reported for cathode materials of rMBs.

Hierarchical LiMn2O4 Hollow Cubes with Exposed {111} Planes as High-Power Cathodes for Lithium-Ion Batteries.

Hierarchical LiMn2O4 hollow cubes with exposed {111} planes have been synthesized using cube-shaped MnCO3 precursors, which are fabricated through a facile co-precipitation reaction. Without surface modification, the as-prepared LiMn2O4 exhibits excellent cyclability and superior rate capability. Surprisingly, even over 70% of primal discharge capacity can be maintained for up to 1000 cycles at 50 C, and with only about 72 s of discharge time the as-prepared materials can deliver initial discharge capacity of 96.5 mA h g(-1). What is more, the materials have 98.4% and 90.7% capacity retentions for up to 100 cycles at 5 C under the temperatures of 25 and 60 °C, respectively. The superior electrochemical performance can be attributed to the unique hierarchical and interior hollow structure, exposed {111} planes, and high-quality crystallinity.

The complete mitochondrial genome of Acanthopagrus schlegelii (Perciformes: Sparidae) with phylogenetic consideration.

The complete mitochondrial genome of the Acanthopagrus schlegelii was presented in this study. The mitochondrial genome is 16 798 bp long and consists of 13 protein-coding genes, two rRNA genes, 22 tRNA genes and a control region. The gene order and composition of Acanthopagrus schlegelii mitochondrial genome was similar to that of most other vertebrates. The nucleotide compositions of the light strand in descending order is 28.04% of T, 27.94% of G, 27.87% of A and 16.15% of C. With the exception of the NADH dehydrogenase subunit 6 (ND6) and eight tRNA genes, all other mitochondrial genes are encoded on the heavy strand. The phylogenetic analysis by maximum-likelihood (ML) method shown that the Acanthopagrus schlegelii has the closer relationship to the Rhabdosargus sarba in the phylogenetic relationship.

The complete mitochondrial genome of Acanthopagrus schlegelii (Perciformes: Sparidae) with phylogenetic consideration.

The complete mitochondrial genome of the Acanthopagrus schlegelii was presented in this study. The mitochondrial genome is 16,798 bp long and consists of 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes and a control region. The gene order and composition of A. schlegelii mitochondrial genome was similar to that of most other vertebrates. The nucleotide compositions of the light strand in descending order is 28.04% of T, 27.94% of G, 27.87% of A and 16.15% of C. With the exception of the NADH dehydrogenase subunit 6 (ND6) and 8 tRNA genes, all other mitochondrial genes are encoded on the heavy strand. The phylogenetic analysis by maximum-likelihood method shown that he A. schlegelii has the closer relationship to the Rhabdosargus sarba in the phylogenetic relationship.

Characterization of the complete mitochondrial genome of Priacanthus tayenus (Perciformes: Priacanthidae) with phylogenetic consideration.

The complete mitochondrial genome of the Priacanthus tayenus was sequenced and analyzed in this study. The mitochondrial genome is 16,866 bp long and consists of 13 protein-coding genes, two rRNA genes, 22 tRNA genes and a control region. The gene order and the composition of P. tayenus mitochondrial genome were similar to that of most other vertebrates. The nucleotide composition of the light strand in descending order is 30.91% of G, 26. 35% of T, 25.61% of A and 17.13% of C. The NADH dehydrogenase subunit 6 (ND6) and eight tRNA genes were localized in the light strand, and all other mitochondrial genes were encoded on the heavy strand. The phylogenetic analysis by maximum-likelihood (ML) method revealed that the P. tayenus showed the closer relationship to the Sciaenops ocellatus.