Interferometric optical testing using computer-generated hologram （CGH） can give highly accurate measurement of aspheric surfaces has been proved. After the system is designed, a phase function is obtained according...Interferometric optical testing using computer-generated hologram （CGH） can give highly accurate measurement of aspheric surfaces has been proved. After the system is designed, a phase function is obtained according to the CGH＇s surface plane. For the requirement of accuracy, an optimization algorithm that transfers the phase function into a certain mask pattern file is presented in this letter, based on the relationship between the pattern error of CGH and the output wavefront accuracy. Then the writing machine is able to fabricate such a mask with this kind of file. With that mask, an improved procedure on fabrication of phase type CGH is also presented. Interferometrie test results of an aspherie surface show that the whole test system obtains the demanded accuracy.展开更多
Despite cities being recognized as being potential sources of microplastic pollution to the wider environment, most surveys of COVID-19 plastic-based litter have been undertaken through linear transects of marine beac...Despite cities being recognized as being potential sources of microplastic pollution to the wider environment, most surveys of COVID-19 plastic-based litter have been undertaken through linear transects of marine beaches. For the far fewer number of studies conducted on inland and urban locations, the site-specific focus has primarily been surveys along the length of streets. The present study is the first to specifically assess the standing stock (i.e., moment-in-time) of littered face masks for the entire surface area of urban parking lots. The density of face masks in 50 parking lots in a Canadian coastal town (0.00054 m2 ± 0.00051 m2) was found to be significantly greater than the background level of littering of town streets. Face mask density was significantly related to visitation “usage” of parking lots as gauged by the areal size of the lots and of their onsite buildings, as well as the number of vehicles present. Neither parking lot typology nor estimates of inferred export (various measures of wind exposure) and entrapment (various metrics of obstruction) of face masks had a significant influence on the extent of whole-lot littering. In consequence, modelling of the potential input of mask-derived microplastics to the marine environment from coastal communities can use the areal density of face masks found here in association with the total surface area of lots for individual municipalities as determined through GIS analysis.展开更多
The worldwide COVID-19 pandemic has led to an attention on the usage of personal protective face masks.However,the longevity and safety of the commercial face masks are limited due to the charge dissipation of the ele...The worldwide COVID-19 pandemic has led to an attention on the usage of personal protective face masks.However,the longevity and safety of the commercial face masks are limited due to the charge dissipation of the electret meltblown nonwovens,which are dominate in the face mask filters.Herein,we design a type of multi-layer structured nonwovens using meltblowing and electrospinning technologies.The complex nonwovens involving meltblown and electrospun fibers are designed to possess multilevel fiber diameters and pore sizes.The micro/nanofibers with porous and wrinkled surface morphologies can well capture particulate matters(PMs),and the multilevel pore sizes contribute to low air resistance under high filtration efficiency.Airflow field simulation was carried out to understand the pressure distribution within the nonwovens in the filtration process.Meanwhile,by adding Ag nanoparticles(AgNPs)as additives,the nonwovens exhibit excellent antibacterial performance.The resultant nonwovens exhibit filtration efficiency of 99.1%for PM0.3 and low pressure drop of 105 Pa under the 10.67 cm/s inlet air velocity,and antibacterial rate of>99.99%for Escherichia coli.These performances and functions make the designed complex nonwovens a promising filter core for face masks.展开更多
文摘Interferometric optical testing using computer-generated hologram （CGH） can give highly accurate measurement of aspheric surfaces has been proved. After the system is designed, a phase function is obtained according to the CGH＇s surface plane. For the requirement of accuracy, an optimization algorithm that transfers the phase function into a certain mask pattern file is presented in this letter, based on the relationship between the pattern error of CGH and the output wavefront accuracy. Then the writing machine is able to fabricate such a mask with this kind of file. With that mask, an improved procedure on fabrication of phase type CGH is also presented. Interferometrie test results of an aspherie surface show that the whole test system obtains the demanded accuracy.
文摘Despite cities being recognized as being potential sources of microplastic pollution to the wider environment, most surveys of COVID-19 plastic-based litter have been undertaken through linear transects of marine beaches. For the far fewer number of studies conducted on inland and urban locations, the site-specific focus has primarily been surveys along the length of streets. The present study is the first to specifically assess the standing stock (i.e., moment-in-time) of littered face masks for the entire surface area of urban parking lots. The density of face masks in 50 parking lots in a Canadian coastal town (0.00054 m2 ± 0.00051 m2) was found to be significantly greater than the background level of littering of town streets. Face mask density was significantly related to visitation “usage” of parking lots as gauged by the areal size of the lots and of their onsite buildings, as well as the number of vehicles present. Neither parking lot typology nor estimates of inferred export (various measures of wind exposure) and entrapment (various metrics of obstruction) of face masks had a significant influence on the extent of whole-lot littering. In consequence, modelling of the potential input of mask-derived microplastics to the marine environment from coastal communities can use the areal density of face masks found here in association with the total surface area of lots for individual municipalities as determined through GIS analysis.
基金the National Natural Science Foundation of China(No.12172087)Shanghai Frontier Science Research Center for Modern Textiles,Donghua University。
文摘The worldwide COVID-19 pandemic has led to an attention on the usage of personal protective face masks.However,the longevity and safety of the commercial face masks are limited due to the charge dissipation of the electret meltblown nonwovens,which are dominate in the face mask filters.Herein,we design a type of multi-layer structured nonwovens using meltblowing and electrospinning technologies.The complex nonwovens involving meltblown and electrospun fibers are designed to possess multilevel fiber diameters and pore sizes.The micro/nanofibers with porous and wrinkled surface morphologies can well capture particulate matters(PMs),and the multilevel pore sizes contribute to low air resistance under high filtration efficiency.Airflow field simulation was carried out to understand the pressure distribution within the nonwovens in the filtration process.Meanwhile,by adding Ag nanoparticles(AgNPs)as additives,the nonwovens exhibit excellent antibacterial performance.The resultant nonwovens exhibit filtration efficiency of 99.1%for PM0.3 and low pressure drop of 105 Pa under the 10.67 cm/s inlet air velocity,and antibacterial rate of>99.99%for Escherichia coli.These performances and functions make the designed complex nonwovens a promising filter core for face masks.
