Targeting micromotion for mimicking natural bone healing by using NIPAM/Nb_(2)C hydrogel

Natural fracture healing is most efficient when the fine-tuned mechanical force and proper micromotion are applied.To mimick this micromotion at the fracture gap,a near-infrared-II(NIR–II)–activated hydrogel was fabricated by integrating two-dimensional(2D)monolayer Nb2C nanosheets into a thermally responsive poly(Nisopropylacrylamide)(NIPAM)hydrogel system.NIR–II–triggered deformation of the NIPAM/Nb2C hydrogel was designed to generate precise micromotion for co-culturing cells.It was validated that micromotion at 1/300 Hz,triggering a 2.37-fold change in the cell length/diameter ratio,is the most favorable condition for the osteogenic differentiation of bone marrow mesenchymal stem cells(BMSCs).Moreover,mRNA sequencing and verification revealed that micromotion-induced augmentation was mediated by Piezo1 activation.Suppression of Piezo1 interrupts the mechano-sensitivity and abrogates osteogenic differentiation.Calvarial and femoral shaft defect models were established to explore the biocompatibility and osteoinductivity of the Micromotion Biomaterial.A series of research methods,including radiography,micro-CT scanning,and immunohistochemical staining have been performed to evaluate biosafety and osteogenic efficacy.The in vivo results revealed that tunable micromotion strengthens the natural fracture healing process through the sequential activation of endochondral ossification,promotion of neovascularization,initiation of mineral deposition,and combinatory acceleration of full-thickness osseous regeneration.This study demonstrated that Micromotion Biomaterials with controllable mechanophysical characteristics could promote the osteogenic differentiation of BMSCs and facilitate full osseous regeneration.The design of NIPAM/Nb2C hydrogel with highly efficient photothermal conversion,specific features of precisely controlled micromotion,and bionic-mimicking bone-repair capabilities could spark a new era in the field of regenerative medicine.

Monolayer graphene/GaN heterostructure photodetector with UV‑IR dual‑wavelength photoresponses

An ultraviolet-infrared(UV-IR)dual-wavelength photodetector(PD)based on a monolayer(ML)graphene/GaN heterostructure has been successfully fabricated in this work.The ML graphene was synthesized by chemical vapor deposition(CVD)and subsequently transferred onto GaN substrate using polymethylmethacrylate(PMMA).The morphological and optical properties of the as-prepared graphene and GaN were presented.The fabricated PD based on the graphene/GaN heterostructure exhibited excellent rectify behavior by measuring the current–voltage(I–V)characteristics under dark conditions,and the spectral response demonstrated that the device revealed an UV-IR dual-wavelength photoresponse.In addition,the energy band structure and absorption properties of the ML graphene/GaN heterostructure were theoretically investigated based on density functional theory(DFT)to explore the underlying physical mechanism of the two-dimensional(2D)/three-dimensional(3D)hybrid heterostructure PD device.This work paves the way for the development of innovative GaNbased dual-wavelength optoelectronic devices,offering a potential strategy for future applications in the field of advanced photodetection technology.

V-substituted pyrochlore-type polyantimonic acid for highly enhanced lithium-ion storage

Pyrochlore-structured polyantimonic acid(PAA)is a potential high-capacity electrode material,but its innately poor electroconductivity(~10^(-10)S/cm)seriously impairs its electrochemical reversibility for lithium-ion storage.Herein,we report design and synthesis of a novel V-substituted PAA(PAA-V),where V^(5+)are introduced to partially replace Sb^(5+).Owing to identical valence and close ionic radius relative to Sb^(5+),the V^(5+)cation can constitute the covalent VO_6octahedra framework without changing the pyrochlore crystal structure of PAA.As a result,the V^(5+)-substitution is capable to modulate the electronic structure of PAA with significantly improved electrical conductivity(~10^(-6)S/cm for PAA-V)and meanwhile decreases the size of crystals with reduced diffusion length for Li^(+)-ions.With varying the ratio of V^(5+)-substitution,the PAA-V with optimized substitution molar ratio(18%)exhibits the best lithium-ion storage performance,delivering a long cycling life with high reversible capacity(731 m Ah/g after 1200cycles at 1 A/g)and outstanding rate capability(279 mAh/g at 15 A/g).More importantly,by pairing the PAA-V as anode and commercial LiFePO_(4)as cathode,the full cell with a limited negative/positive capacity ratio of 1.2 exhibits decent cycling stability at 1 C after 150 cycles with 85.5%capacity retention.

Fast optical-writing recognition based on two-dimensional photothermoelectric effect assisted with deep learning

The photothermoelectric(PTE)effect enables a simple structure to construct a noncontact and self-powered writing device.PTE detectors based on active materials and one-dimensional(1D)position-sensitive PTE effect have attracted considerable attentions.However,there is no research on applying the 1D position-sensitive PTE effect to a two-dimensional(2D)surface.Besides,flexible writing devices based on the PTE effect have not been reported.Here,we demonstrate a self-powered flexible optical writing device based on the 2D position-sensitive PTE effect of SnSe thin film.Laser positioning,tracking,and distinguishing of optically written characters have been realized by only measuring the bi-directional output voltages during the writing process.A deep convolutional neural network has been introduced to recognize optically written numbers and characters with high recognition accuracy(92%)and fast processing speed(8.6 ms).The flexible optical-writing device with a simple structure could rapidly and accurately recognize characters in a noncontact fashion using a small amount of training data.