Biodegradable polymers are highly attractive as potential alternatives to petroleum-based polymers in an attempt to achieve carbon neutrality whilst maintaining the mechanical properties of the structures.Among these ...Biodegradable polymers are highly attractive as potential alternatives to petroleum-based polymers in an attempt to achieve carbon neutrality whilst maintaining the mechanical properties of the structures.Among these polymers,polylactic acid(PLA)is particularly promising due to its good mechanical properties,biocompatibility and thermoplasticity.In this work,we aim to enhance the mechanical properties of PLA using mechanically-defibrated cellulose nanofibers(CNFs)that exhibit remarkable mechanical properties and biodegradability.We also employ fused deposition modeling(FDM),one of the three-dimensional printing methods for thermoplastic polymers,for the low-cost fabrication of the products.Mechanically-defibrated CNF-reinforced PLA matrix composites are fabricated by FDM.Their tensile properties are investigated in two printing directions(0°/90°and+45°/-45°).The discussion about the relationship between printing direction and tensile behavoir of mechanically-defibrated CNF-reinforced PLA matrix composite is the unique point of this study.We further discuss the microstructure and fracture surface of mechanically-defibrated CNF-reinforced PLA matrix composite by scanning electron microscope.展开更多
Two anaerobic membrane bioreactors(AnMBRs)equipped with different membrane pore size(0.4 or 0.05μm)were operated at 25℃and fed with domestic wastewater.The hydraulic retention time(HRT)of the reactors was shortened....Two anaerobic membrane bioreactors(AnMBRs)equipped with different membrane pore size(0.4 or 0.05μm)were operated at 25℃and fed with domestic wastewater.The hydraulic retention time(HRT)of the reactors was shortened.The microbial communities of the two AnMBRs were investigated by 16S rRNA gene amplicon sequencing to see the effects of HRT.The predominant Archaea was an aceticlastic methanogen Methanosaeta.The composition of hydrogenotrophic methanogens changed with the HRTs:the population of Methanobacterium was higher for longer HRTs,whereas the population of unclassified Methanoregulaceae was higher for shorter HRTs.The Anaerolineae,Bacteroidia and Clostridia bacteria were dominant in both of the reactors,with a combined relative abundance of over 55%.The relative abundance of Anaerolineae was proportional to the biogas production performance.The change in the population of hydrogenotrophic methanogens or Anaerolineae can be used as an indicator for process monitoring.The sum of the relative abundance of Anaerolineae and Clostridia fluctuated slightly with changes in the HRT in both AnMBRs when the reactor was stably operated.The co-occurrence analysis revealed the relative abundance of the operational taxonomic units belonging to Anaerolineae and Clostridia was functionally equivalent during the treatment of real domestic sewage.A principal coordination analysis revealed that the changes in the microbial community in each reactor were consistent with the change of HRT.In addition,both the HRT and the stability of the process are important factors for maintaining microbial community structures.展开更多
Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)is involved in aerosol particles and droplets excreted from a coronavirus disease 2019(COVID-19)patient.Such aerosol particles or droplets including infectiou...Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)is involved in aerosol particles and droplets excreted from a coronavirus disease 2019(COVID-19)patient.Such aerosol particles or droplets including infectious virions can be attached on fomite,so fomite is not a negligible route for SARS-CoV-2 transmission within a community,especially in indoor environment.This necessarily evokes a need of fomite disinfection to remove virions,but the extent to which fomite disinfection breaks off virus transmission chain in indoor environment is still elusive.In this study,we evaluated the fomite disinfection effectiveness on COVID-19 case number using network analysis that reproduced the reported indoor outbreaks.In the established network,virus can move around not only human but also air and fomite while growing in human and decaying in air and on fomite,and infection success was determined based on the exposed virus amount and the equation of probability of infection.The simulation results have demonstrated that infectious virions on fomite should be kept less than a hundred to sufficiently reduce COVID-19 case,and every-hour disinfection was required to avoid stochastic increase in the infection case.This study gives us a practical disinfection manner for fomite to control SARS-CoV-2 transmission in indoor environment.展开更多
基金supported by the Program for Creation of Interdisciplinary Research and Ensemble Program of Frontier Research Institute for Interdisciplinary Sciences,Tohoku University。
文摘Biodegradable polymers are highly attractive as potential alternatives to petroleum-based polymers in an attempt to achieve carbon neutrality whilst maintaining the mechanical properties of the structures.Among these polymers,polylactic acid(PLA)is particularly promising due to its good mechanical properties,biocompatibility and thermoplasticity.In this work,we aim to enhance the mechanical properties of PLA using mechanically-defibrated cellulose nanofibers(CNFs)that exhibit remarkable mechanical properties and biodegradability.We also employ fused deposition modeling(FDM),one of the three-dimensional printing methods for thermoplastic polymers,for the low-cost fabrication of the products.Mechanically-defibrated CNF-reinforced PLA matrix composites are fabricated by FDM.Their tensile properties are investigated in two printing directions(0°/90°and+45°/-45°).The discussion about the relationship between printing direction and tensile behavoir of mechanically-defibrated CNF-reinforced PLA matrix composite is the unique point of this study.We further discuss the microstructure and fracture surface of mechanically-defibrated CNF-reinforced PLA matrix composite by scanning electron microscope.
基金supported by Grant-in-Aids for JSPS Fellows(KAKENHI Grant nos.JP19J11931 and JP19J12023)Scientific Research(B)(KAKENHI Grant no.JP18H01564)+1 种基金Scientific Research(A)(KAKENHI Grant no.JP19H01160)from Japan Society for the Promotion of Scienceby Ministry of the Environment,Japan(Low Carbon Technology Research,Development and Demonstration Program:Innovative sewage treatment system for energy saving and energy production,20172019)。
文摘Two anaerobic membrane bioreactors(AnMBRs)equipped with different membrane pore size(0.4 or 0.05μm)were operated at 25℃and fed with domestic wastewater.The hydraulic retention time(HRT)of the reactors was shortened.The microbial communities of the two AnMBRs were investigated by 16S rRNA gene amplicon sequencing to see the effects of HRT.The predominant Archaea was an aceticlastic methanogen Methanosaeta.The composition of hydrogenotrophic methanogens changed with the HRTs:the population of Methanobacterium was higher for longer HRTs,whereas the population of unclassified Methanoregulaceae was higher for shorter HRTs.The Anaerolineae,Bacteroidia and Clostridia bacteria were dominant in both of the reactors,with a combined relative abundance of over 55%.The relative abundance of Anaerolineae was proportional to the biogas production performance.The change in the population of hydrogenotrophic methanogens or Anaerolineae can be used as an indicator for process monitoring.The sum of the relative abundance of Anaerolineae and Clostridia fluctuated slightly with changes in the HRT in both AnMBRs when the reactor was stably operated.The co-occurrence analysis revealed the relative abundance of the operational taxonomic units belonging to Anaerolineae and Clostridia was functionally equivalent during the treatment of real domestic sewage.A principal coordination analysis revealed that the changes in the microbial community in each reactor were consistent with the change of HRT.In addition,both the HRT and the stability of the process are important factors for maintaining microbial community structures.
基金supported by MHLW Research on Health Security Control Program Grant Number JPMH21LA1007.
文摘Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)is involved in aerosol particles and droplets excreted from a coronavirus disease 2019(COVID-19)patient.Such aerosol particles or droplets including infectious virions can be attached on fomite,so fomite is not a negligible route for SARS-CoV-2 transmission within a community,especially in indoor environment.This necessarily evokes a need of fomite disinfection to remove virions,but the extent to which fomite disinfection breaks off virus transmission chain in indoor environment is still elusive.In this study,we evaluated the fomite disinfection effectiveness on COVID-19 case number using network analysis that reproduced the reported indoor outbreaks.In the established network,virus can move around not only human but also air and fomite while growing in human and decaying in air and on fomite,and infection success was determined based on the exposed virus amount and the equation of probability of infection.The simulation results have demonstrated that infectious virions on fomite should be kept less than a hundred to sufficiently reduce COVID-19 case,and every-hour disinfection was required to avoid stochastic increase in the infection case.This study gives us a practical disinfection manner for fomite to control SARS-CoV-2 transmission in indoor environment.
