Heat preservation,antifouling,hemostatic and antibacterial aerogel wound dressings for emergency treatment

Hemostatic dressings with multiple functions are superior to current hemostatic dressings for use in the complex situation of emergency accidents.In particular,the existing dressings lack consideration for the prevention of hypothermic shock after massive hemorrhage.In this study,gelatin(GN)and oxidized pectin(OP)were used for Schiff base cross-linking,and then polyvinyl alcohol(PVA)solution mixed with hemostatic caffeic acid(CA)was introduced to obtain aerogel substrate material(CB)after lyophilization.Polydimethylsiloxane(PDMS)and silver nanowires(Ag NWs)were used to construct a hydrophobic layer,an antibacterial layer and an infrared reflective layer on both sides of CB to prepare a multifunctional aerogel wound dressing with heat preservation,antifouling,hemostasis and antibacterial properties(PDMS-Ag NW-CB).The results showed that the infrared transmittance of PDMS-Ag NW-CB is almost 0,so that thermal energy loss from the body is minimized.The contact angles with water and blood are 129°and 120°,respectively,which have the effect of antifouling.This dressing can absorb blood quickly within 10 min,adhere to and gather platelets,and achieve hemostasis.It has good antibacterial and biocompatibility.Therefore,PDMS-Ag NW-CB has great potential in application to emergency treatment.

Multi-scale structure engineering of covalent organic framework for electrochemical charge storage

Covalent organic frameworks(COFs),which are constructed by linking organic building blocks via dynamic covalent bonds,are newly emerged and burgeoning crystalline porous copolymers with features including programmable topological architecture,pre-designable periodic skeleton,well-defined micro-/meso-pore,large specific surface area,and customizable electroactive functionality.Those benefits make COFs as promising candidates for advanced electrochemical energy storage.Especially,for now,structure engineering of COFs from multiscale aspects has been conducted to enable optimal overall electrochemical performance in terms of structure durability,electrical conductivity,redox activity,and charge storage.In this review,we give a fundamental and insightful study on the correlations between multi-scale structure engineering and eventual electrochemical properties of COFs,started with introducing their basic chemistries and charge storage principles.The careful discussion on the significant achievements in structure engineering of COFs from linkages,redox sites,polygon skeleton,crystal nanostructures,and composite microstructures,and further their effects on the electrochemical behavior of COFs are presented.Finally,the timely cutting-edge perspectives and in-depth insights into COFbased electrodematerials to rationally screen their electrochemical behaviors for addressing future challenges and implementing electrochemical energy storage applications are proposed.

Economy Analysis of Flexible LCC-HVDC Systems with Controllable Capacitors

Commutation failure(CF)is a frequent dynamic event at inverter of LCC-HVDC systems caused by AC side faults which can lead to inverter blocking,interruption of active power transfer,and even system blackout.To eliminate CFs and improve system performance,new Flexible LCC-HVDC topologies have been proposed in previous research but with limited analysis on its economic performance.Therefore,to further validate the applicability of Flexible LCC-HVDC topologies,this paper utilizes Life-Cycle Cost Analysis model to analyze the life-cycle cost of inverter stations for conventional LCCHVDC,Capacitor Commutated Converter based HVDC(CCCHVDC)topology and Flexible LCC-HVDC topologies including Controllable Capacitor based Flexible LCC-HVDC,AC Filterless Controllable Capacitor based Flexible LCC-HVDC and improved Flexible LCC-HVDC.Through a case study based on a 500 kV,1000 MW LCC-HVDC scheme,comparison results show that the AC Filterless Controllable Capacitor based Flexible LCCHVDC topology and the improved Flexible LCC-HVDC topology have lower cost than the conventional LCC-HVDC and CCCHVDC topologies,which proves that the elimination of CFs can be achieved with reduced cost.