Suppress oxygen evolution of lithium-rich manganese-based cathode materials via an integrated strategy

Improving the reversibility of anionic redox and inhibiting irreversible oxygen evolution are the main challenges in the application of high reversible capacity Li-rich Mn-based cathode materials.A facile synchronous lithiation strategy combining the advantages of yttrium doping and LiYO_(2) surface coating is proposed.Yttrium doping effectively suppresses the oxygen evolution during the delithiation process by increasing the energy barrier of oxygen evolution reaction through strong Y–O bond energy.LiYO_(2) nanocoating has the function of structural constraint and protection,that protecting the lattice oxygen exposed to the surface,thus avoiding irreversible oxidation.As an Li^(+) conductor,LiYO_(2) nano-coating can provide a fast Li^(+) transfer channel,which enables the sample to have excellent rate performance.The synergistic effect of Y doping and nano-LiYO_(2) coating integration suppresses the oxygen release from the surface,accelerates the diffusion of Li^(+)from electrolyte to electrode and decreases the interfacial side reactions,enabling the lithium ion batteries to obtain good electrochemical performance.The lithium-ion full cell employing the Y-1 sample(cathode)and commercial graphite(anode)exhibit an excellent specific energy density of 442.9 Wh kg^(-1) at a current density of 0.1C,with very stable safety performance,which can be used in a wide temperature range(60 to-15℃)stable operation.This result illustrates a new integration strategy for advanced cathode materials to achieve high specific energy density.

Plasma preparation of highly reactive Ag-Cu NPs anchored in N-PC as catalysts for Aluminum-air battery

Efficient,stable and economical catalysts play a crucial role in enhancing the kinetics of slow oxygen reduction reactions(ORR)in Aluminum-air batteries.Among the potential next-generation candidates,Ag catalysts are promising due to their high activity and low cost,but weaker oxygen adsorption has hindered industrialization.To address this bottleneck,Ag-alloying has emerged as a principal strategy.In this work,we successfully prepared Ag-Cu nanoparticles(NPs)with a rich eutectic phase and uniform dispersion structure using plasma evaporation.The increased solid solution of Ag and Cu led to changes in the electronic structure,resulting in an upward shift of the d-band center,which significantly improved oxygen adsorption.The combination of Ag and Cu in the NPs synergistically enhanced the adsorption of Ag and the desorption of Cu.Density functional theory(DFT)calculations revealed that Ag-Cu25 NPs exhibited the smallest limiting reaction barrier,leading to increased ORR activity.To further optimize the catalyst’s performance,we utilized N-doped porous nanocarbon(N-PC)with high electrical conductivity and abundant mesoporous channels as the support for the Ag-Cu NPs.The N-PC support provided optimal mass transfer carriers for the highly active Ag-Cu25 NPs.As a result,the Ag-Cu25/NPC catalyst displayed excellent ORR activity in alkaline media,with a half-wave potential(E_(1/2))of 0.82 V.Furthermore,the Al-air battery incorporating the Ag-Cu25/NPC catalyst exhibited outstanding electrochemical performance.It demonstrated high open-circuit voltages of 1.89 V and remarkable power densities of 193 m W cm^(-2).The battery also sustained a high current output and maintained a stable high voltage for 120 hours under mechanical charging,showcasing its significant potential for practical applications.

Bone tissue engineering scaffold materials: Fundamentals, advances, and challenges

Bone damage caused by trauma and tumors is a serious problem for human health, therefore, three-dimensional (3D) scaffolding materials that stimulate and promote the regeneration of broken bone tissues have become the focus of current research in the field of bone damage repair.To this regard, a preferential combination of materials and preparation techniques is considered crucial for the preparation of advanced bone tissue engineering scaffolds to better facilitate the regeneration of broken bone.In this review, current research advances and challenges in bone tissue engineering scaffolds are discussed and analyzed in detail.First, we elucidated the structure and self-healing mechanism of bone tissue.Subsequently, the main applications of different materials, including inorganic and organic materials, in bone tissue engineering scaffolds are summarized.Moreover, we overview the latest research progress of the mainstream preparation strategies of bone tissue engineering scaffolds, and provide an in-depth analysis of the different advantages of each method.Finally, promising future directions and challenges of bone tissue engineering scaffolds are systematically discussed.

Exosome-functionalized magnesium-organic framework-based scaffoldswith osteogenic, angiogenic and anti-inflammatory properties foraccelerated bone regeneration

Exosomes derived from human adipose-derived stem cells (hADSCs-Exos) have shown potential as an effectivetherapeutic tool for repairing bone defects. Although metal-organic framework (MOF) scaffolds are promisingstrategies for bone tissue regeneration, their potential use for exosome loading remains unexplored. In this study,motivated by the potential advantages of hADSCs-Exos and Mg-GA MOF, we designed and synthesized anexosome-functionalized cell-free PLGA/Mg-GA MOF (PLGA/Exo-Mg-GA MOF) scaffold, taking using of thebenefits of hADSCs-Exos, Mg2+, and gallic acid (GA) to construct unique nanostructural interfaces to enhanceosteogenic, angiogenic and anti-inflammatory capabilities simultaneously. Our in vitro work demonstrated thebeneficial effects of PLGA/Exo-Mg-GA MOF composite scaffolds on the osteogenic effects in human bonemarrow-derived mesenchymal stem cells (hBMSCs) and angiogenic effects in human umbilical endothelial cells(HUVECs). Slowly released hADSCs-Exos from composite scaffolds were phagocytosed by co-cultured cells,stabilized the bone graft environment, ensured blood supply, promoted osteogenic differentiation, and acceleratedbone reconstruction. Furthermore, our in vivo experiments with rat calvarial defect model showed thatPLGA/Exo-Mg-GA MOF scaffolds promoted new bone formation and satisfactory osseointegration. Overall, weprovide valuable new insights for designing exosome-coated nanocomposite scaffolds with enhanced osteogenesisproperty.

Integration exosomes with MOF-modified multifunctional scaffold for accelerating vascularized bone regeneration

Designing a multifunctional scaffold with osteogenic and angiogenic properties holds promise for ideal bone regeneration. Innovative scaffold was here constructed by immobilizing exosomes derived from human bone mesenchymal stem cells(h BMSCs) onto porous polymer meshes which developed by PLGA and Cu-based MOF(PLGA/Cu BDC@Exo). The synthesized exosome-laden scaffold capable of providing a dual cooperative controllable release of bioactive copper ions and exosomes that promote osteogenesis and angiogenesis, thereby achieving cell-free bone regeneration. In vitro assay revealed the composite stent not only substantially upregulated the expression of osteogenic-related proteins(ALP, Runx2, Ocn)and VEGF in h BMSCs, but promoted the migration and tube formation of the human umbilical vein endothelial cells(HUVECs). In vivo evaluation further confirmed this scaffold dramatically stimulated bone regeneration and angiogenesis in critical-sized defects in rats. Altogether, this composite scaffold carrying therapeutic exosomes had an osteogenic-angiogenic coupling effect and offered a new idea for cell-free bone tissue engineering.

Iron-based metal-organic framework as a dual cooperative release system for enhanced vascularization and bone regeneration

Vascularization and bone regeneration are closely related in the process of bone remodeling,and designing a bioactive scaffold with pro-angiogenic and osteogenic properties may accelerate the repair of bone defects.In this work,an iron-based metal-organic framework(MIL-88)was developed as a carrier for loading a pro-angiogenic small molecular drug(dimethyloxallyl glycine,DMOG),and then embedded into the PLGA nanofibrous scaffolds to repair cranial defects in rats.Imaging and histological evaluation indicated that PLGA/MIL@D scaffold markedly enhanced vascularization and bone regeneration in vivo.Moreover,in vitro assay showed that co-delivery system significantly promoted angiogenesis by stimulating endothelial cell migration,tube formation,and enhanced osteogenesis by promoting expression of osteoblast related proteins.In addition,PLGA/MIL@D scaffold promotes angiogenesis by activating the hypoxia-inducible factor-1(HIF-1)/vascular endothelial growth factor(VEGF)signaling pathway.Altogether,this bioactive PLGA/MIL@D scaffold can combine angiogenesis with osteogenesis,and will be a bright strategy for the repair of bone defects.

Hydrogel electrodes with conductive and substrate-adhesive layers for noninvasive long-term EEG acquisition

Noninvasive brain–computer interfaces (BCIs) show great potential in applications including sleep monitoring, fatigue alerts, neurofeedback training, etc. While noninvasive BCIs do not impose any procedural risk to users (as opposed to invasive BCIs), the acquisition of high-quality electroencephalograms (EEGs) in the long term has been challenging due to the limitations of current electrodes. Herein, we developed a semidry double-layer hydrogel electrode that not only records EEG signals at a resolution comparable to that of wet electrodes but is also able to withstand up to 12 h of continuous EEG acquisition. The electrode comprises dual hydrogel layers: a conductive layer that features high conductivity, low skin-contact impedance, and high robustness;and an adhesive layer that can bond to glass or plastic substrates to reduce motion artifacts in wearing conditions. Water retention in the hydrogel is stable, and the measured skin-contact impedance of the hydrogel electrode is comparable to that of wet electrodes (conductive paste) and drastically lower than that of dry electrodes (metal pin). Cytotoxicity and skin irritation tests show that the hydrogel electrode has excellent biocompatibility. Finally, the developed hydrogel electrode was evaluated in both N170 and P300 event-related potential (ERP) tests on human volunteers. The hydrogel electrode captured the expected ERP waveforms in both the N170 and P300 tests, showing similarities in the waveforms generated by wet electrodes. In contrast, dry electrodes fail to detect the triggered potential due to low signal quality. In addition, our hydrogel electrode can acquire EEG for up to 12 h and is ready for recycled use (7-day tests). Altogether, the results suggest that our semidry double-layer hydrogel electrodes are able to detect ERPs in the long term in an easy-to-use fashion, potentially opening up numerous applications in real-life scenarios for noninvasive BCI.

鞘状碳纳米管人工肌肉纤维在弱电流刺激下的驱动性能提升机制

电热驱动的鞘状人工肌肉已经展示出广阔的应用前景.当受到高电流产生的焦耳热影响时,它们的鞘层会膨胀和软化,有效地释放芯部纤维内储存的扭转能量,这种现象显著地提高了驱动性能.本工作制备了一种包裹在聚二甲基硅氧烷(PDMS)鞘层中的预捻碳纳米管(CNT)人工肌肉纤维.施加频率为0.25 Hz的50 mA电流,其可以产生13.28%的收缩变形和9.82 MPa的收缩应力,功率密度为3.8 W g^(−1).得益于非螺旋结构,CNT纤维@PDMS的运行速率可达42%s^(−1),我们据此开发了快速运行的开关和仿生臂.有趣的是,我们观察到即使在较弱的电流不足以诱导驱动所需的PDMS鞘层膨胀和软化的情况下,CNT纤维@PDMS的驱动性能也有所改善.为了解释这一现象,我们提出了一种鞘层致密化机制.当电流通入CNT纤维时,其内部CNTs间产生的安培吸引力也会引发驱动,PDMS鞘层在固化过程中产生沿CNT纤维径向分布的收缩应力,会使CNTs间距减小,从而提升安培吸引力.我们通过检测CNT纤维@PDMS在不同温度下的驱动行为、内部微观结构、力学和电学性能的变化证实了这种致密化机制的存在,并分析了整个驱动过程中能量的变化.

Properties and mechanism of ionic liquid/silicone oil based magnetorheological fluids

A magnetorheological fluid(MRF)is a smart composite suspension composed of nonmagnetic liquid and soft magnetic particles.Carrier fluids can considerably influence the performance of MRFs;therefore,to investigate the effect of carrier fluids on MRFs,an SO/IL-MRF was prepared by mixing an ionic liquid(IL)with silicone oil(SO)in this study.Three types of MRF samples were prepared for experiments(pure SO,pure IL,and SO/IL).According to the experi-mental results,the SO/IL-MRF has better sedimentation stability than those based on pure SO and pure IL.Further,three methods were used to determine the shear yield stresses of the MRFs.The SO/IL-MRF achieved a higher shear yield stress than those of the other two because a network structure is formed between the ionic fragments and the molecular chains of the SO in the SO/IL-MRF.This increases the movement resistance of the particles in the carrier fluid,and it is unlike the mechanism of the IL-enhanced MRF.This work provides new ideas for improving the MRF performance.