Double network self-healing hydrogel based on hydrophobic association and ionic bond for formation plugging

Self-healing hydrogels have attracted tremendous attention in the field of oil and gas drilling and production engineering because of their excellent self-healing performance after physical damage.In this study,a series of double network self-healing(DN_(SA))hydrogels based on hydrophobic association and ionic bond were prepared for plugging pores and fractures in formations in oil and gas drilling and production engineering.The mechanical,rheological,and self-healing properties of the DN_(SA)hydrogels were investigated.Results revealed that the DN_(SA)hydrogels exhibited excellent mechanical properties with a tensile stress of 0.67 MPa and toughness of 7069 kJ/cm^(3) owing to the synergistic effect of the double network.In addition,the DN_(SA)hydrogels exhibited excellent compression resistance,notch insensitivity,and self-healing properties.The DN_(SA)-2 hydrogel was granulated and made into gel particles with different particle sizes and used as a plugging agent.The self-healing mechanism of DN_(SA)-2 hydrogel particles in fractures was explored,and it’s plugging effect on fractures of different widths and porous media of different permeabilities were investigated.Experimental results revealed that the plugging capacity of the DN_(SA)-2 hydrogel particles for a fracture with width of 5 mm and a porous medium with a permeability of 30μm^(2) was 3.45 and 4.21 MPa,respectively,which is significantly higher than those of commonly used plugging agents in the oilfield.The DN_(SA)hydrogels with excellent mechanical and self-healing properties prepared in this study will provide a new approach for applying hydrogels in oil and gas drilling and production engineering.

Mechanical reliable,NIR light-induced rapid self-healing hydrogel electrolyte towards flexible zinc-ion hybrid supercapacitors with low-temperature adaptability and long service life

Hydrogel electrolytes hold great potential in flexible zinc ion supercapacitors(ZICs)due to their high conductivity,good safety,and flexibility.However,freezing of electrolytes at low temperature(subzero)leads to drastic reduction in ionic conductivity and mechanical properties that deteriorates the performance of flexible ZICs.Besides,the mechanical fracture during arbitrary deformations significantly prunes out the lifespan of the flexible device.Herein,a Zn^(2+)and Li^(+)co-doped,polypyrrole-dopamine decorated Sb_(2)S_(3)incorporated,and polyvinyl alcohol/poly(N-(2-hydroxyethyl)acrylamide)double-network hydrogel electrolyte is constructed with favorable mechanical reliability,anti-freezing,and self-healing ability.In addition,it delivers ultra-high ionic conductivity of 8.6 and 3.7 S m^(-1)at 20 and−30°C,respectively,and displays excellent mechanical properties to withstand tensile stress of 1.85 MPa with tensile elongation of 760%,together with fracture energy of 5.14 MJ m^(-3).Notably,the fractured hydrogel electrolyte can recover itself after only 90 s of infrared illumination,while regaining 83%of its tensile strain and almost 100%of its ionic conductivity during−30–60°C.Moreover,ZICs coupled with this hydrogel electrolyte not only show a wide voltage window(up to 2 V),but also provide high energy density of 230 Wh kg^(-1)at power density of 500 W kg^(-1)with a capacity retention of 86.7%after 20,000 cycles under 20°C.Furthermore,the ZICs are able to retain excellent capacity even under various mechanical deformation at−30°C.This contribution will open up new insights into design of advanced wearable flexible electronics with environmental adaptability and long-life span.

A Self-Healing Optoacoustic Patch with High Damage Threshold and Conversion Efficiency for Biomedical Applications

Compared with traditional piezoelectric ultrasonic devices,optoacoustic devices have unique advantages such as a simple preparation process,anti-electromagnetic interference,and wireless long-distance power supply.However,current optoacoustic devices remain limited due to a low damage threshold and energy conversion efficiency,which seriously hinder their widespread applications.In this study,using a self-healing polydimethylsiloxane(PDMS,Fe-Hpdca-PDMS)and carbon nanotube composite,a flexible optoacoustic patch is developed,which possesses the self-healing capability at room temperature,and can even recover from damage induced by cutting or laser irradiation.Moreover,this patch can generate high-intensity ultrasound(>25 MPa)without the focusing structure.The laser damage threshold is greater than 183.44 mJ cm^(-2),and the optoacoustic energy conversion efficiency reaches a major achievement at 10.66×10^(-3),compared with other carbon-based nanomaterials and PDMS composites.This patch is also been successfully examined in the application of acoustic flow,thrombolysis,and wireless energy harvesting.All findings in this study provides new insight into designing and fabricating of novel ultrasound devices for biomedical applications.

High performance photodegradation resistant PVA@TiO_(2)/carboxyl-PES self-healing reactive ultrafiltration membrane

The occurrence of ultrafiltration(UF)membrane fouling frequently hampers the sustainable advancement of UF technology.Reactive self-cleaning UF membranes can effectively alleviate the problem of membrane fouling.Nevertheless,the self-cleaning process may accelerate membrane aging.Addressing these concerns,we present an innovative design concept for composite self-healing materials based on self-cleaning UF membranes.To begin,TiO_(2)nanoparticles were incorporated into the polymer molecular structure via molecular design,resulting in the synthesis of TiO_(2)/carboxyl-polyether sulfone(PES)hybrid materials.Subsequently,the nonsolvent-induced phase inversion technique was employed to prepare a novel of UF membrane.Lastly,a polyvinyl alcohol(PVA)hydrogel coating was applied to the hybrid UF membrane surface to create PVA@TiO_(2)/carboxyl-PES self-healing reactive UF membranes.By establishing a covalent bond,the TiO_(2)nanoparticles were effectively and uniformly dispersed within the UF membrane,leading to exceptional self-cleaning properties.Furthermore,the water-absorbing and swelling properties of PVA hydrogel,along with its capacity to form hydrogen bonds with water molecules,resulted in UF membranes with improved hydrophilicity and active self-healing abilities.The results demonstrated that the water contact angle of PVA@5%TiO_(2)/carboxyl-PES UF membrane was 43.1°.Following a 1-h exposure to simulated solar exposure,the water flux recovery ratio increased from 48.16%to 81.03%.Moreover,even after undergoing five cycles of 12-h simulated sunlight exposure,the UF membranes exhibited a consistent retention rate of over 97%,thus fully demonstrating their exceptional self-cleaning,antifouling,and selfhealing capabilities.We anticipate that the self-healing reactive UF membrane system will serve as a pioneering and comprehensive solution for the self-cleaning antifouling challenges encountered in UF membranes while also effectively mitigating the aging effects of reactive UF membranes.

An intrinsically self-healing and anti-freezing molecular chains induced polyacrylamide-based hydrogel electrolytes for zinc manganese dioxide batteries

The anti-freezing strategy of hydrogels and their self-healing structure are often contradictory,it is vital to break through the molecular structure to design and construct hydrogels with intrinsic anti-freezing/self-healing for meeting the rapid development of flexible and wearable devices in diverse service conditions.Herein,we design a new hydrogel electrolyte(AF/SH-Hydrogel)with intrinsic anti-freezing/self-healing capabilities by introducing ethylene glycol molecules,dynamic chemical bonding(disulfide bond),and supramolecular interaction(multi-hydrogen bond)into the polyacrylamide molecular chain.Thanks to the exceptional freeze resistance(84%capacity retention at-20℃)and intrinsic self-healing capabilities(95%capacity retention after 5 cutting/self-healing cycles),the obtained AF/SH-Hydrogel makes the zinc||manganese dioxide cell an economically feasible battery for the state-of-the-art applications.The Zn||AF/SH-Hydrogel||MnO_(2)device offers a near-theoretical specific capacity of 285 m A h g^(-1)at 0.1 A g^(-1)(Coulombic efficiency≈100%),as well as good self-healing capability and mechanical flexibility in an ice bath.This work provides insight that can be utilized to develop multifunctional hydrogel electrolytes for application in next generation of self-healable and freeze-resistance smart aqueous energy storage devices.

Effect of drying cracks on swelling and self-healing of bentonite-sand blocks used as engineered barriers for radioactive waste disposal

Experiments were conducted to evaluate the healing of drying cracks in air-dried bentonite-sand blocks after hydration and swelling in groundwater,providing justifications to simplify the protection of blocks prior to installation in a high-level radioactive waste repository.Synthetic groundwater was prepared to represent the geochemistry of Beishan groundwater,and was used to hydrate the blocks during the swelling pressure and swelling strain measurements,as Beishan is the most promising site for China's repository.Healing of the surface cracks was recorded by photography,and healing of the internal cracks was visualized by CT images and hydraulic conductivity of air-dried blocks.The results indicate that the maximum swelling pressure and swelling strain are primarily affected by the geochemistry of Beishan groundwater,but not affected by the drying cracks.The maximum swelling pressure and swelling strain of air-dried blocks are comparable to or even higher than the pressure and strain of fresh blocks.The maximum swelling pressure measured in strong(i.e.high ion strength)Beishan groundwater was 44%of the pressure measured in deionized(DI)water,and the maximum swelling strain was reduced to 23%of the strain measured in DI water.Nevertheless,the remained swelling of the blocks hydrated in strong Beishan groundwater was sufficient to heal the surface and internal drying cracks,as demonstrated by the pictures of surface cracks and CT images.The hydraulic conductivity of the air-dried block permeated with strong groundwater was comparable(3.7×higher)to the hydraulic conductivity of the fresh block,indicating the self-healing of drying cracks after hydration and swelling in groundwater.A simplified method of protecting the block with plastic wraps before installation is recommended,since the remained swelling of the block hydrated in Beishan groundwater is sufficient to heal the drying cracks.

A Self-Healing and Nonflammable Cross-Linked Network Polymer Electrolyte with the Combination of Hydrogen Bonds and Dynamic Disulfide Bonds for Lithium Metal Batteries

The self-healing solid polymer electrolytes(SHSPEs)can spontaneously eliminate mechanical damages or micro-cracks generated during the assembly or operation of lithium-ion batteries(LIBs),significantly improving cycling performance and extending service life of LIBs.Here,we report a novel cross-linked network SHSPE(PDDP)containing hydrogen bonds and dynamic disulfide bonds with excellent self-healing properties and nonflammability.The combination of hydrogen bonding between urea groups and the metathesis reaction of dynamic disulfide bonds endows PDDP with rapid self-healing capacity at 28°C without external stimulation.Furthermore,the addition of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide(EMIMTFSI)improves the ionic conductivity(1.13×10^(−4)S cm^(−1)at 28°C)and non-flammability of PDDP.The assembled Li/PDDP/LiFePO_(4)cell exhibits excellent cycling performance with a discharge capacity of 137 mA h g^(−1)after 300 cycles at 0.2 C.More importantly,the self-healed PDDP can recover almost the same ionic conductivity and cycling performance as the original PDDP.

Self-Healing Liquid Metal Magnetic Hydrogels for Smart Feedback Sensors and High-Performance Electromagnetic Shielding

Hydrogels exhibit potential applications in smart wearable devices because of their exceptional sensitivity to various external stimuli.However,their applications are limited by challenges in terms of issues in biocompatibility,custom shape,and self-healing.Herein,a conductive,stretchable,adaptable,self-healing,and biocompatible liquid metal GaInSn/Ni-based composite hydrogel is developed by incorporating a magnetic liquid metal into the hydrogel framework through crosslinking polyvinyl alcohol(PVA)with sodium tetraborate.The excellent stretchability and fast self-healing capability of the PVA/liquid metal hydrogel are derived from its abundant hydrogen binding sites and liquid metal fusion.Significantly,owing to the magnetic constituent,the PVA/liquid metal hydrogel can be guided remotely using an external magnetic field to a specific position to repair the broken wires with no need for manual operation.The composite hydrogel also exhibits sensitive deformation responses and can be used as a strain sensor to monitor various body motions.Additionally,the multifunctional hydrogel displays absorption-dominated electromagnetic interference(EMI)shielding properties.The total shielding performance of the composite hydrogel increases to~62.5 dB from~31.8 dB of the pure PVA hydrogel at the thickness of 3.0 mm.The proposed bioinspired multifunctional magnetic hydrogel demonstrates substantial application potential in the field of intelligent wearable devices.

Intrinsic Self-Healing Chemistry for Next-Generation Flexible Energy Storage Devices

The booming wearable/portable electronic devices industry has stimulated the progress of supporting flexible energy storage devices.Excellent performance of flexible devices not only requires the component units of each device to maintain the original performance under external forces,but also demands the overall device to be flexible in response to external fields.However,flexible energy storage devices inevitably occur mechanical damages(extrusion,impact,vibration)/electrical damages(overcharge,over-discharge,external short circuit)during longterm complex deformation conditions,causing serious performance degradation and safety risks.Inspired by the healing phenomenon of nature,endowing energy storage devices with self-healing capability has become a promising strategy to effectively improve the durability and functionality of devices.Herein,this review systematically summarizes the latest progress in intrinsic self-healing chemistry for energy storage devices.Firstly,the main intrinsic self-healing mechanism is introduced.Then,the research situation of electrodes,electrolytes,artificial interface layers and integrated devices based on intrinsic self-healing and advanced characterization technology is reviewed.Finally,the current challenges and perspective are provided.We believe this critical review will contribute to the development of intrinsic self-healing chemistry in the flexible energy storage field.

Self-Healing MXene-and Graphene-Based Composites:Properties and Applications

Today,self-healing graphene-and MXene-based composites have attracted researchers due to the increase in durability as well as the cost reduction in long-time applications.Different studies have focused on designing novel self-healing graphene-and MXenebased composites with enhanced sensitivity,stretchability,and flexibility as well as improved electrical conductivity,healing efficacy,mechanical properties,and energy conversion efficacy.These composites with self-healing properties can be employed in the field of wearable sensors,supercapacitors,anticorrosive coatings,electromagnetic interference shielding,electronic-skin,soft robotics,etc.However,it appears that more explorations are still needed to achieve composites with excellent arbitrary shape adaptability,suitable adhesiveness,ideal durability,high stretchability,immediate self-healing responsibility,and outstanding electromagnetic features.Besides,optimizing reaction/synthesis conditions and finding suitable strategies for functionalization/modification are crucial aspects that should be comprehensively investigated.MXenes and graphene exhibited superior electrochemical properties with abundant surface terminations and great surface area,which are important to evolve biomedical and sensing applications.However,flexibility and stretchability are important criteria that need to be improved for their future applications.Herein,the most recent advancements pertaining to the applications and properties of self-healing graphene-and MXene-based composites are deliberated,focusing on crucial challenges and future perspectives.

“Smart”micro/nano container-based self-healing coatings on magnesium alloys:A review

Coating technologies are a commonly used way to protect metals against corrosion.However,with more and more severe service environments of materials,many protective coating systems often are not environmentally friendly or toxic as in the case of chromates.Based on the world’s abundant ideal magnesium(Mg)and its alloy,the smart self-healing anticorrosive coating can autonomously restore the damaged part of the coating according to the environmental changes,strengthen the corrosion protection ability,and prolong its service life.This paper reviews the research progress of smart self-healing coatings on Mg alloys.These coatings mostly contain suitable corrosion inhibitors encapsulated into micro/nano containers.Moreover,the different self-healing mechanisms and functionalities of micro/nano containers are discussed.The micro/nano containers range from inorganic nanocontainers such as mesoporous nanoparticles(silica(SiO_(2)),titanium dioxide(TiO_(2)),etc.),over inorganic clays(halloysite,hydrotalcite-like,zeolite),to organic nanocontainers such as polymer microcapsules,nanofibers,chitosan(CS)and cyclodextrin(CD),as well as,carbon materials such as graphene and carbon nanotubes and hybrids such as metal organic frameworks.The functioning of micro/nano containers can be divided in two principal groups:autonomous(based on defect filling and corrosion inhibition)and non-autonomous(based on dynamic bonds and shape memory polymers).Moreover,multi functionalities and composite applications of various micro/nano containers are summarized.At present,significant progress has been made in the preparation methods and technologies of micro/nano containers.Achieving long-term self-healing properties of coatings sensing of coating failure and early warning after self-healing function failure can be expected as the main development direction of self-healing corrosion protection coatings in the future.

Self-healing wearable self-powered deep ultraviolet photodetectors based on Ga_(2)O_(3)

Gallium oxide(Ga_(2)O_(3))based flexible heterojunction type deep ultraviolet(UV)photodetectors show excellent solar-blind photoelectric performance,even when not powered,which makes them ideal for use in intelligent wearable devices.How-ever,traditional flexible photodetectors are prone to damage during use due to poor toughness,which reduces the service life of these devices.Self-healing hydrogels have been demonstrated to have the ability to repair damage and their combination with Ga_(2)O_(3) could potentially improve the lifetime of the flexible photodetectors while maintaining their performance.Herein,a novel self-healing and self-powered flexible photodetector has been constructed onto the hydrogel substrate,which exhibits an excellent responsivity of 0.24 mA/W under 254 nm UV light at zero bias due to the built-in electric field originating from the PEDOT:PSS/Ga_(2)O_(3) heterojunction.The self-healing of the Ga_(2)O_(3) based photodetector was enabled by the reversible property of the synthesis of agarose and polyvinyl alcohol double network,which allows the photodetector to recover its original configu-ration and function after damage.After self-healing,the photocurrent of the photodetector decreases from 1.23 to 1.21μA,while the dark current rises from 0.95 to 0.97μA,with a barely unchanged of photoresponse speed.Such a remarkable recov-ery capability and the photodetector’s superior photoelectric performance not only significantly enhance a device lifespan but also present new possibilities to develop wearable and intelligent electronics in the future.

The Optimization Study about Fault Self-Healing Restoration of Power Distribution Network Based on Multi-Agent Technology

In order to quickly and accurately locate the fault location of the distribution network and increase the stability of the distribution network,a fault recovery method based on multi-objective optimization algorithm is proposed.The optimization of the power distribution network fault system based on multiagent technology realizes fast recovery of multi-objective fault,solve the problem of network learning and parameter adjustment in the later stage of particle swarm optimization algorithm falling into the local extreme value dilemma,and realize the multi-dimensional nonlinear optimization of the main grid and the auxiliary grid.The system proposed in this study takes power distribution network as the goal,applies fuzzy probability algorithm,simplifies the calculation process,avoids local extreme value,and finally realizes the energy balance between each power grid.Simulation results show that the Multi-Agent Technology enjoys priority in restoring important load,shortening the recovery time of power grid balance,and reducing the overall line loss rate of power grid.Therefore,the power grid fault self-healing system can improve the safety and stability of the important power grid,and reduce the economic loss rate of the whole power grid.

Screening biomarkers for spinal cord injury using weighted gene co-expression network analysis and machine learning

Immune changes and inflammatory responses have been identified as central events in the pathological process of spinal co rd injury.They can greatly affect nerve regeneration and functional recovery.However,there is still limited understanding of the peripheral immune inflammato ry response in spinal cord inju ry.In this study.we obtained microRNA expression profiles from the peripheral blood of patients with spinal co rd injury using high-throughput sequencing.We also obtained the mRNA expression profile of spinal cord injury patients from the Gene Expression Omnibus(GEO)database(GSE151371).We identified 54 differentially expressed microRNAs and 1656 diffe rentially expressed genes using bioinformatics approaches.Functional enrichment analysis revealed that various common immune and inflammation-related signaling pathways,such as neutrophil extracellular trap formation pathway,T cell receptor signaling pathway,and nuclear factor-κB signal pathway,we re abnormally activated or inhibited in spinal cord inju ry patient samples.We applied an integrated strategy that combines weighted gene co-expression network analysis,LASSO logistic regression,and SVM-RFE algorithm and identified three biomarke rs associated with spinal cord injury:ANO10,BST1,and ZFP36L2.We verified the expression levels and diagnostic perfo rmance of these three genes in the original training dataset and clinical samples through the receiver operating characteristic curve.Quantitative polymerase chain reaction results showed that ANO20 and BST1 mRNA levels were increased and ZFP36L2 mRNA was decreased in the peripheral blood of spinal cord injury patients.We also constructed a small RNA-mRNA interaction network using Cytoscape.Additionally,we evaluated the proportion of 22 types of immune cells in the peripheral blood of spinal co rd injury patients using the CIBERSORT tool.The proportions of naive B cells,plasma cells,monocytes,and neutrophils were increased while the proportions of memory B cells,CD8^(+)T cells,resting natural killer cells,resting dendritic cells,and eosinophils were markedly decreased in spinal cord injury patients increased compared with healthy subjects,and ANO10,BST1 and ZFP26L2we re closely related to the proportion of certain immune cell types.The findings from this study provide new directions for the development of treatment strategies related to immune inflammation in spinal co rd inju ry and suggest that ANO10,BST2,and ZFP36L2 are potential biomarkers for spinal cord injury.The study was registe red in the Chinese Clinical Trial Registry(registration No.ChiCTR2200066985,December 12,2022).

Wide temperature range-and damage-tolerant microsupercapacitors from salt-tolerant, anti-freezing and self-healing organohydrogel via dynamic bonds modulation

The advance of microelectronics requires the micropower of microsupercapacitors(MSCs) to possess wide temperature-and damage-tolerance beyond high areal energy density.The properties of electrolyte are crucial for MSCs to meet the above requirements.Here,an organohydrogel electrolyte,featured with high salt tolerance,ultralow freezing point,and strong self-healing ability,is experimentally realized via modulating its inner dynamic bonds.Spectroscopic and theoretical analysis reveal that dimethyl sulfoxide has the ability to reconstruct Li^(+)solvation structure,and interact with free water and polyvinyl alcohol chains via forming hydrogen bonds.The organohydrogel electrolyte is employed to build MSCs,which show a boosted energy density,promising wide temperature range-and damage-tolerant ability.These attractive features make the designed organohydrogel electrolyte have great potential to advance MSCs.

A self-healing and conductive ionic hydrogel based on polysaccharides for flexible sensors

In this study,we proposed a self-healing conductive hydrogel based on polysaccharides and Li+to serve as flexible sensors.At first,the oxidized sodium alginate(OSA)was obtained through the oxidation reaction of sodium alginate(SA).Then OSA,carboxymethyl chitosan(CMC),and agarose(AGO)were dissolved in LiCl solution,respectively.Finally,the hydrogel was obtained through heating,mixing,and cooling processes.Because of the Schiff base structure and hydrogen bonding,the hydrogel demonstrates good mechanical and self-healing properties.The presence of Li+provides good conductivity for the hydrogel.In addition,we demonstrated the application of the hydrogel as the flexible sensors.It can perceive the process of pressing Morse code with the index finger as a pressure sensor and monitor sliding movement of the thumb as the strain sensor to browse the web with the mobile phone.Thus,the selfhealing conductive hydrogel may have potential applications in flexible wearable sensors.

Thermo-driven oleogel-based self-healing slippery surface behaving superior corrosion inhibition to Mg-Li alloy

Bioinspired by Nepenthes, lubricant infused surfaces(LIS) have attracted widespread attention in the field of anticorrosion. However,the lubricant coating has some disadvantages such as complex construction processing and easy loss of oil phase in air or dynamic water phase. In this study, oleogel is infused into a lotus leaf inspired super-hydrophobic matrix to form an oleogel infused surface(OIS) for enhancing corrosion resistance of active Mg-Li alloy. For reserving oleogel, firstly, a facile one-step electrodeposition method is used to construct super-hydrophobic surface(SHS) composed by samarium/myristic acid complex micro-nano flower structure onto Mg-Li alloy.The coating exhibits excellent superhydrophobic property at a static contact angle of 160° by applying 30 V electrolysis for 30 min. The protection efficiency of single SHS highly relates with the metal itself. For short period immersion in water phase, SHS can afford protection to Mg-Li alloy. However, the long-term immersion will see the rapid failure of SHS, and the high activity of Mg-Li alloy is one main reason.We assume that SHS cannot be a good choice for protecting Mg-Li alloy. Then, a Nepenthes inspired liquid coating is formed by infusing oleogel into the micro-nano structure by a spin-coating method. The liquid coating performs prominent corrosion resistance with Rctreaching as high as 1.51 × 10^(10)Ω cm^(2). After the mechanical damage from the external environment, the liquid coating can realize self-repair through thermal assistance, and the liquid coating can still restore Rctup to 1.24 × 10^(10)Ω cm^(2) after healing. The corrosion resistance of the liquid coating remains strong by showing Rctas high as 1.14 × 10^(9)Ω cm^(2), even after immersion in representative corrosive 3.5 wt% Na Cl solution for 30 d.

Pluggable multitask diffractive neural networks based on cascaded metasurfaces

Optical neural networks have significant advantages in terms of power consumption,parallelism,and high computing speed,which has intrigued extensive attention in both academic and engineering communities.It has been considered as one of the powerful tools in promoting the fields of imaging processing and object recognition.However,the existing optical system architecture cannot be reconstructed to the realization of multi-functional artificial intelligence systems simultaneously.To push the development of this issue,we propose the pluggable diffractive neural networks(P-DNN),a general paradigm resorting to the cascaded metasurfaces,which can be applied to recognize various tasks by switching internal plug-ins.As the proof-of-principle,the recognition functions of six types of handwritten digits and six types of fashions are numerical simulated and experimental demonstrated at near-infrared regimes.Encouragingly,the proposed paradigm not only improves the flexibility of the optical neural networks but paves the new route for achieving high-speed,low-power and versatile artificial intelligence systems.

Recyclability and Self-Healing of Dynamic Cross-Linked Polyimide with Mechanical/Electrical Damage

Recyclability and self-healing are two most critical factors in developing sustainable polymers to deal with environmental pollution and resource waste.In this work,a dynamic cross-linked polyimide insulation film with full closed-loop recyclability is successfully prepared,which also possesses good self-healing ability after being mechanical/electrical damaged depending on the Schiff base dynamic covalent bonds.The recycled and self-healed polyimide film still maintain its good tensile strength(r t)>60 MPa with Young’s modulus(E)>4 GPa,high thermal stability with glass transition temperature(T g)>220℃,and outstanding insulation property with breakdown strength(E 0)>358 kV mm^(-1),making it a very promising low energy consumption and high temperature resistant insulation material.The strategy of using Schiff base dynamic covalent bonds for reversible repairing the structure of high T g polyimides promotes the wider application of such sustainable and recyclable material in the field of electrical power and micro-electronics.

Social-ecological perspective on the suicidal behaviour factors of early adolescents in China:a network analysis

Background In early adolescence,youth are highly prone to suicidal behaviours.Identifying modifiable risk factors during this critical phase is a priority to inform effective suicide prevention strategies.Aims To explore the risk and protective factors of suicidal behaviours(ie,suicidal ideation,plans and attempts)in early adolescence in China using a social-ecological perspective.Methods Using data from the cross-sectional project‘Healthy and Risky Behaviours Among Middle School Students in Anhui Province,China',stratified random cluster sampling was used to select 5724 middle school students who had completed self-report questionnaires in November 2020.Network analysis was employed to examine the correlates of suicidal ideation,plans and attempts at four levels,namely individual(sex,academic performance,serious physical llness/disability,history of self-harm,depression,impulsivity,sleep problems,resilience),family(family economic status,relationship with mother,relationship with father,family violence,childhood abuse,parental mental illness),school(relationship with teachers,relationship with classmates,school-bullying victimisation and perpetration)and social(social support,satisfaction with society).Results In total,37.9%,19.0%and 5.5%of the students reported suicidal ideation,plans and attempts in the past 6 months,respectively.The estimated network revealed that suicidal ideation,plans and attempts were collectively associated with a history of self-harm,sleep problems,childhood abuse,school bullying and victimisation.Centrality analysis indicated that the most influential nodes in the network were history of self-harm and childhood abuse.Notably,the network also showed unique correlates of suicidal ideation(sex,weight=0.60;impulsivity,weight=0.24;family violence,weight=0.17;relationship with teachers,weight=-0.03;school-bullying perpetration,weight=0.22),suicidal plans(social support,weight=-0.15)and suicidal attempts(relationship with mother,weight=-0.10;parental mental llness,weight=0.61).Conclusions This study identified the correlates of suicidal ideation,plans and attempts,and provided practical implications for suicide prevention for young adolescents in China.Firstly,this study highlighted the importance of joint interventions across multiple departments.Secondly,the common risk factors of suicidal ideation,plans and attempts were elucidated.Thirdly,this study proposed target interventions to address the unique influencing factors of suicidal ideation,plans and attempts.