surface modification

摘要： The introduction of neurotrophic factors into injured peripheral nerve sites is beneficial to peripheral nerve regeneration.However,neurotrophic facto rs are rapidly degraded in vivo and obstruct axonal regeneration when used at a supraphysiological dose,which limits their clinical benefits.Bioactive mimetic peptides have been developed to be used in place of neurotrophic factors because they have a similar mode of action to the original growth fa ctors and can activate the equivalent receptors but have simplified sequences and structures.In this study,we created polydopamine-modified chitin conduits loaded with brain-derived neurotrophic factor mimetic peptides and vascular endothelial growth fa ctor mimetic peptides(Chi/PDA-Ps).We found that the Chi/PDA-Ps conduits were less cytotoxic in vitro than chitin conduits alone and provided sustained release of functional peptides.In this study,we evaluated the biocompatibility of the Chi/P DA-Ps conduits.Brain-derived neurotrophic factor mimetic peptide and vascular endothelial growth fa ctor mimetic peptide synergistically promoted prolife ration of Schwann cells and secretion of neurotrophic factors by Schwann cells and attachment and migration of endothelial cells in vitro.The Chi/P DA-Ps conduits were used to bridge a 2 mm gap between the nerve stumps in rat models of sciatic nerve injury.We found that the application of Chi/PDA-Ps conduits could improve the motor function of rats and reduce gastrocnemius atrophy.The electrophysiological results and the microstructure of regenerative nerves showed that the nerve conduction function and re myelination was further resto red.These findings suggest that the Chi/PDA-Ps conduits have great potential in peripheral nerve injury repair.

摘要： Rechargeable aqueous Zn-ion batteries(AZIBs)are one of the most promising energy storage devices for large-scale energy storage owing to their high specific capacity,eco-friendliness,low cost and high safety.Nevertheless,zinc metal anodes suffer from severe dendrite growth and side reactions,resulting in the inferior electrochemical performance of AZIBs.To address these problems,surface modification of zinc metal anodes is a facile and effective method to regulate the interaction between the zinc anode and an electrolyte.In this review,the current challenges and strategies for zinc metal anodes are presented.Furthermore,recent advances in surface modification strategies to improve their electrochemical performance are concluded and discussed.Finally,challenges and prospects for future development of zinc metal anodes are proposed.We hope this review will be useful for designing and fabricating highperformance AZIBs and boosting their practical applications.

摘要： The flashover performance of insulating materials plays an important role in the development of high-voltage insulation systems.In this paper,silicone rubber(SIR)is modified by CF4 radio frequency capacitively coupled plasma(CCP)for the improvement of surface insulation performance.The discharge mode and active particles of CCP are diagnosed by the digital single-lens reflex and the spectrometer.Scanning electron microscopy and x-ray photoelectron spectroscopy are used for the surface physicochemical properties of samples,while the surface charge dissipation,charge accumulation measurement,and flashover test are applied for the surface electrical characteristics.Experimental results show that the fluorocarbon groups can be grafted and the surface roughness increases after plasma treatment.Besides,the surface charge dissipation is decelerated and the positive charge accumulation is inhibited obviously for the treated samples.Furthermore,the surface flashover voltage can be increased by 26.67%after 10 min of treatment.It is considered that strong electron affinity of C–F and increased surface roughness can contribute to deepening surface traps,which not only inhibits the development of secondary electron emission avalanche but also alleviates the surface charge accumulation and finally improves the surface flashover voltage of SIR.

摘要： Stainless steel,titanium alloys,cobalt-chromium alloys and other metal materials are the most widely used orthopaedic implants.However,there are still some problems in clinical application,including a mechanical mismatch between metal and bone,inflammation and secondary operation.As a new generation of medical metal materials,magnesium(Mg)and its alloys have attracted much attention due to their excellent biodegradability.Biodegradable Mg-based metals have good mechanical and osteogenic properties,and are expected to become implant materials to treat challenging orthopaedic diseases.However,the rapid corrosion rate is still one of the main challenges restricting its clinical application.Alloy and surface modification are effective methods to control the corrosion rate of Mg alloys.This paper reviews the mechanical and biological properties of biodegradable Mg alloys and the problems when they are applied clinically,emphasizing the latest progress of Mg-based metals in alloying and surface modification.The status of the application of Mg-based implants in orthopaedics are also described.

摘要： The use of organically enhanced kaolin clay as reinforcing filler for NR(natural rubber)and blends of NR with NBR(nitrile-butadiene rubber)and poly BR(butadiene rubber)system were investigated on the basis of DMA(dynamic mechanical analysis).Kaolin clay was modified using a chemical complex of HH(hydrazine hydrate)and SRSO(sodium salt of rubber seed oil).Intercalation of SRSO into kaolin under optimized condition showed an inter-lamellar layer expansion to 4.668 nm,compared to the characteristic d001 XRD(X-ray diffraction)peak of pristine kaolin at 0.714 nm.The morphology,visco-elastic behavior,modulus property,polymer miscibility and Tg(glass transition temperature)of nano-kaolin filled NR and its blend with synthetic rubbers have been studied in detail.DMA showed a diminution in tanδpeak height and a modulus shift in correspondence with increased CLD(crosslink density).Pure NR shows only~1%increase in storage modulus(E′)while adding nanoclay rather than micron sized pristine clay under experimental conditions,because of the feeble interaction between filler and matrix,as compared to blend.An increment of~76%and~117%in E′was recognized by the addition of 4 wt%nanoclay in blends such as BR mK and NBR mK.With loss modulus(E″)pure NR shows only~7%decrease while adding nanoclay,compared to blend.A decrement of~54%and~55%in E″by the addition of 4 wt%nanoclay in BR mK and NBR mK blends were observed.As a whole,DMA was performed to figure out the effect of surface modification enabling to materialize composite.

摘要： Fluoroalkyl end-capped vinyltrimethoxysilane-N,N-dimethylacrylamide cooligomer [RF-(CH2-CHSi(OMe)3)x-(CH2-CHC(=O)NMe2)y-RF;RF = CF(CF3)OC3F7: RF-(VM)x-(DMAA)y-RF] was synthesized by reaction of fluoroalkanoyl peroxide [RF-C(=O)O-O(O=)C-RF] with vinyltrimethoxysilane (VM) and N,N-dimethylacrylamide (DMAA). The modified glass surface treated with the cooligomeric nanoparticles [RF-(VM-SiO3/2)x-(DMAA)y-RF] prepared under the sol-gel reaction of the cooligomer under alkaline conditions was found to exhibit an oleophobic/superhydrophilic property, although the corresponding fluorinated homooligomeric nanoparticles [RF-(VM-SiO3/2)n-RF] afforded an oleophobic/hydrophobic property on the modified surface under similar conditions. RF-(VM-SiO3/2)n-RF/RF-(VM-SiO3/2)x-(DMAA)y-RF/PSt (micro-sized polystyrene particles) composites, which were prepared by the sol-gel reactions of the corresponding homooligomer and cooligomer in the presence of PSt particle under alkaline conditions, provided an oleophobic/superhydrophilic property on the modified surface. However, it was demonstrated that the surface wettability on the modified surface treated with the RF-(VM-SiO3/2)n-RF/RF-(VM-SiO3/2)x-(DMAA)y-RF/PSt composites changes dramatically from oleophobic/superhydrophilic to superoleophilic/superhydrophilic and superoleophilic/superhydrophobic characteristics, increasing with greater feed ratios (mg/mg) of the RF-(VM)n-RF homooligomer in homooligomer/cooligomer from 0 to 100 in the preparation of the composites. Such controlled surfac

摘要： Polytetrafluoroethylene(PTFE)is a low-background polymer that is applied to several applications in rare-event detection and underground low-background experiments.PTFE-based electronic substrates are important for reducing the detection limit of high-purity germanium detectors and scintillator calorimeters,which are widely applied in dark matter and 0υββdetection experiments.The traditional adhesive bonding method between PTFE and copper is not conducive to working in liquid nitrogen and extremely low-temperature environments.To avoid adhesive bonding,PTFE must be processed for surface metallization owing to the mismatch between the PTFE and copper conductive layer.Low-background PTFE matrix composites(m-PTFE)were selected to improve the electrical and mechanical properties of PTFE by introducing SiO_(2)/TiO_(2) particles.The microstructures,surface elements,and electrical properties of PTFE and m-PTFE were characterized and analyzed following ion implantation.PTFE and m-PTFE surfaces were found to be broken,degraded,and cross-linked by ion implantation,resulting in C=C conjugated double bonds,increased surface energy,and increased surface roughness.Comparably,the surface roughness,bond strength,and conjugated double bonds of m-PTFE were significantly more intense than those of PTFE.Moreover,the interface bonding theory between PTFE and the metal copper foil was analyzed using the direct metallization principle.Therefore,the peel strength of the optimized electronic substrates was higher than that of the industrial standard at extremely low temperatures,while maintaining excellent electrical properties.

摘要： Extracorporeal membrane oxygenator(ECMO) has been in development for nearly 70 years, and the oxygenator has gone through several generations of optimizations, with advances from bubble oxygenators to membrane oxygenators leading to more and more widespread use of ECMO. Membrane is the core of a ECMO system and the working mechanism of membrane oxygenator depends on the membrane material,from PDMS flat membrane to PMP hollow fiber membrane, which have experienced three generations.Blood compatibility on the surface of the membrane material is very vital, which directly determines the use duration of the oxygenator and can reduce the occurrence of complications. The mechanism of mass transfer is the basis of oxygenator operation and optimization. This review summarizes the membrane development history and preparation technology, modification approaches and mass transfer theory in the process of oxygen and blood exchange. We hoped that this review will provide more ideas for the study of gas blood exchange membrane.

摘要： Zinc metal anodes face several challenges,including the uncontrolled formation of dendrites,hydrogen evolution,and corrosion,which seriously hinder their application in practice.To address the above problems such as dendrite formation and corrosion,we present a simple and applicable immersion method that enables in situ formation of a zinc phytate(PAZ)coating on the surface of commercial Zn flakes via a substitution reaction.This protective coating mitigates corrosion of zinc flakes by the electrolyte,reduces the interfacial impedance,and accelerates the migration kinetics of zinc ions.Besides,this method can preferentially expose the(002)crystal plane with strong atomic bonding,which not only improves the corrosion resistance of the zinc flake,but can also guide the parallel deposition of zinc ions along the(002)crystal plane and reduce the formation of dendrites.Benefiting from the above advantages,the PAZ@Zn‖Cu half-cell has shown over 900 cycles with average coulombic efficiency(CE)of99.81%at 4 mA cm^(-2).Besides,the PAZ@Zn‖PAZ@Zn symmetric cell operate stably for>1000 h at5 mA cm^(-2)and>340 h at 10 mA cm^(-2).Furthermore,we demonstrated that this in situ chemical treatment enables the formation of a robust,well-bound protective coating.This method provides insights for advancing the commercialization of zinc anodes and other metal anodes.

摘要： Poly(ethylene oxide)(PEO)-based solid polymer electrolyte(SPE)is considered as a promising solid-state electrolyte for all-solid-state lithium batteries(ASSLBs).Nevertheless,the poor interfacial stability with high-voltage cathode materials(e.g.,LiCoO_(2))restricts its application in high energy density solid-state batteries.Herein,high-voltage stable Li3AlF6 protective layer is coated on the surface of LiCoO_(2) particle to improve the performance and investigate the fail-ure mechanism of PEO-based ASSLBs.The phase transition unveils that chemical redox reaction occurs between the highly reactive LiCoO_(2) surface and PEO-based SPE,resulting in structure collapse of LiCoO_(2),hence the poor cycle performance of PEO-based ASSLBs with LiCoO_(2) at charging voltage of 4.2 V vs Li/Li+.By sharp contrast,no obvious structure change can be found at the surface of Li3AlF6-coated LiCoO2,and the original layered phase was well retained.When the charging voltage reaches up to 4.5 V vs Li/Li+,the intensive electrochemical decomposition of PEO-based SPE occurs,leading to the constant increase of cell impedance and directly causing the poor performance.This work not only provides important supplement to the failure mechanism of PEO-based batter-ies with LiCoO_(2),but also presents a universal strategy to retain structure stability of cathode-electrolyte interface in high-voltage ASSLBs.