According to Le Chatelier's principle,increasing the reaction pressure of O_(2) is expected to significantly enhance H_(2) O_(2) electrosynthesis performance,but this effect remains unexplored.By comparing various...According to Le Chatelier's principle,increasing the reaction pressure of O_(2) is expected to significantly enhance H_(2) O_(2) electrosynthesis performance,but this effect remains unexplored.By comparing various catalysts under different pressures,we uncover an intriguing phenomenon.Namely,in a pressurized electrolyzer(2.0 V,30 bar O_(2)),a microporous metal-organic framework(MAF-2) with enzyme-mimicking dicopper(I) active sites on its pore surface achieved a current density of 90 m A cm^(-2),Faradaic efficiency of ~95%,a record yield rate of 4.2 mol g_(cat)^(-1)h^(-1),and record energy conversion efficiency of 27% for H_(2) O_(2) production,generating pure and salt-free H_(2) O_(2) at medical-grade concentration(3.3 wt%).Notably,this performance at30 bar O_(2) is seven times higher than at 1 bar O_(2).The performance increase caused by this pressurization far exceeds those of other types of catalysts(e.g.,carbon black and BBL-PcNi covalent framework),which rely solely on particle-surface active sites and exhibit <10% pressure response.Mechanism studies reveal that while O_(2) struggles to enter MAF-2 pores at 1 bar(uptake <2 cm^(3)g^(-1)),pressurization facilitates oxygen entering the pores(adsorption enthalpy =-45 kJ mol^(-1),uptake = 40 cm^(3)g^(-1)at30 bar) and contact with abundant highly active dicopper(I) sites on the pore surface,thereby significantly enhancing its highpressure performance.This study highlights the synergistic advantages of dual active sites and MOF porosities in electrocatalytic gas molecule conversion,providing critical insights for designing high-performance catalysts under high pressure.展开更多
Indeed,medicinal importance of honey has been documented in the world's oldest medical literatures,and since the ancient times,it has been known to possess antimicrobial property as well as wound-healing activity....Indeed,medicinal importance of honey has been documented in the world's oldest medical literatures,and since the ancient times,it has been known to possess antimicrobial property as well as wound-healing activity.The healing property of honey is due to the fact that it offers antibacterial activity,maintains a moist wound condition,and its high viscosity helps to provide a protective barrier to prevent infection.Its immunomodulatory property is relevant to wound repair too.The antimicrobial activity in most honeys is due to the enzymatic production of hydrogen peroxide.However,another kind of honey,called non-peroxide honey(viz.,manuka honey),displays significant antibacterial effects even when the hydrogen peroxide activity is blocked.Its mechanism may be related to the low pH level of honey and its high sugar content(high osmolality) that is enough to hinder the growth of microbes.The medical grade honeys have potent in vitro bactericidal activity against antibiotic-resistant bacteria causing several life-threatening infections to humans. But,there is a large variation in the antimicrobial activity of some natural honeys,which is due to spatial and temporal variation in sources of nectar.Thus,identification and characterization of the active principle(s) may provide valuable information on the quality and possible therapeutic potential of honeys(against several health disorders of humans),and hence we discussed the medicinal property of honeys with emphasis on their antibacterial activities.展开更多
Expanded polytetrafluoroethylene(ePTFE)is promising in biomedical fields such as covered stents and plastic surgery owing to its excellent biocompatibility and mechanical properties.However,ePTFE material prepared by ...Expanded polytetrafluoroethylene(ePTFE)is promising in biomedical fields such as covered stents and plastic surgery owing to its excellent biocompatibility and mechanical properties.However,ePTFE material prepared by the traditional biaxial stretching process is with thicker middle and thinner sides due to the bowing effect,which poses a major problem in industrial-scale fabrication.To solve this problem,we design an olive-shaped winding roller to provide the middle part of the ePTFE tape with a greater longitudinal stretching amplitude than the two sides,so as to make up for the excessive longitudinal retraction tendency of the middle part when it is transversely stretched.The as-fabricated ePTFE membrane has,as designed,uniform thickness and node-fibril microstructure.In addition,we examine the effects of mass ratio of lubricant to PTFE powder,biaxial stretching ratio and sintering temperature on the performance of the resultant ePTFE membranes.Particularly,the relation between the internal microstructure of the ePTFE membrane and its mechanical properties is revealed.Besides stable mechanical properties,the sintered ePTFE membrane exhibits satisfactory biological properties.We make a series of biological assessments including in vitro hemolysis,coagulation,bacterial reverse mutation and in vivo thrombosis,intracutaneous reactivity test,pyrogen test and subchronic systemic toxicity test;all of the results meet the relevant international standards.The muscle implantation of the sintered ePTFE membrane into rabbits indicates acceptable inflammatory reactions of our sintered ePTFE membrane fabricated on industrial scale.Such a medical-grade raw material with the unique physical form and condensed-state microstructure is expected to afford an inert biomaterial potentially for stent-graft membrane.展开更多
基金supported by the National Key R&D Program of China (2024YFF0506100)the National Natural Science Foundation of China (NSFC)(22090061,22488101,22371304)+3 种基金the Special Fund Project for Science and Technology Innovation Strategy of Guangdong Province (STKJ2023078)the Fundamental Research Funds for the Central Universitiesthe Sun Yat-sen University (24lgzy006)the Guangzhou Science and Technology Program (SL2023A04J01767)。
文摘According to Le Chatelier's principle,increasing the reaction pressure of O_(2) is expected to significantly enhance H_(2) O_(2) electrosynthesis performance,but this effect remains unexplored.By comparing various catalysts under different pressures,we uncover an intriguing phenomenon.Namely,in a pressurized electrolyzer(2.0 V,30 bar O_(2)),a microporous metal-organic framework(MAF-2) with enzyme-mimicking dicopper(I) active sites on its pore surface achieved a current density of 90 m A cm^(-2),Faradaic efficiency of ~95%,a record yield rate of 4.2 mol g_(cat)^(-1)h^(-1),and record energy conversion efficiency of 27% for H_(2) O_(2) production,generating pure and salt-free H_(2) O_(2) at medical-grade concentration(3.3 wt%).Notably,this performance at30 bar O_(2) is seven times higher than at 1 bar O_(2).The performance increase caused by this pressurization far exceeds those of other types of catalysts(e.g.,carbon black and BBL-PcNi covalent framework),which rely solely on particle-surface active sites and exhibit <10% pressure response.Mechanism studies reveal that while O_(2) struggles to enter MAF-2 pores at 1 bar(uptake <2 cm^(3)g^(-1)),pressurization facilitates oxygen entering the pores(adsorption enthalpy =-45 kJ mol^(-1),uptake = 40 cm^(3)g^(-1)at30 bar) and contact with abundant highly active dicopper(I) sites on the pore surface,thereby significantly enhancing its highpressure performance.This study highlights the synergistic advantages of dual active sites and MOF porosities in electrocatalytic gas molecule conversion,providing critical insights for designing high-performance catalysts under high pressure.
文摘Indeed,medicinal importance of honey has been documented in the world's oldest medical literatures,and since the ancient times,it has been known to possess antimicrobial property as well as wound-healing activity.The healing property of honey is due to the fact that it offers antibacterial activity,maintains a moist wound condition,and its high viscosity helps to provide a protective barrier to prevent infection.Its immunomodulatory property is relevant to wound repair too.The antimicrobial activity in most honeys is due to the enzymatic production of hydrogen peroxide.However,another kind of honey,called non-peroxide honey(viz.,manuka honey),displays significant antibacterial effects even when the hydrogen peroxide activity is blocked.Its mechanism may be related to the low pH level of honey and its high sugar content(high osmolality) that is enough to hinder the growth of microbes.The medical grade honeys have potent in vitro bactericidal activity against antibiotic-resistant bacteria causing several life-threatening infections to humans. But,there is a large variation in the antimicrobial activity of some natural honeys,which is due to spatial and temporal variation in sources of nectar.Thus,identification and characterization of the active principle(s) may provide valuable information on the quality and possible therapeutic potential of honeys(against several health disorders of humans),and hence we discussed the medicinal property of honeys with emphasis on their antibacterial activities.
基金supports from National Natural Science Foundation of China(grant no.52130302)National Key R&D Program of China(grant no.2016YFC1100300)。
文摘Expanded polytetrafluoroethylene(ePTFE)is promising in biomedical fields such as covered stents and plastic surgery owing to its excellent biocompatibility and mechanical properties.However,ePTFE material prepared by the traditional biaxial stretching process is with thicker middle and thinner sides due to the bowing effect,which poses a major problem in industrial-scale fabrication.To solve this problem,we design an olive-shaped winding roller to provide the middle part of the ePTFE tape with a greater longitudinal stretching amplitude than the two sides,so as to make up for the excessive longitudinal retraction tendency of the middle part when it is transversely stretched.The as-fabricated ePTFE membrane has,as designed,uniform thickness and node-fibril microstructure.In addition,we examine the effects of mass ratio of lubricant to PTFE powder,biaxial stretching ratio and sintering temperature on the performance of the resultant ePTFE membranes.Particularly,the relation between the internal microstructure of the ePTFE membrane and its mechanical properties is revealed.Besides stable mechanical properties,the sintered ePTFE membrane exhibits satisfactory biological properties.We make a series of biological assessments including in vitro hemolysis,coagulation,bacterial reverse mutation and in vivo thrombosis,intracutaneous reactivity test,pyrogen test and subchronic systemic toxicity test;all of the results meet the relevant international standards.The muscle implantation of the sintered ePTFE membrane into rabbits indicates acceptable inflammatory reactions of our sintered ePTFE membrane fabricated on industrial scale.Such a medical-grade raw material with the unique physical form and condensed-state microstructure is expected to afford an inert biomaterial potentially for stent-graft membrane.
