In the context of global COVID-19 epidemic preparedness,the extensive use of disposable surgical masks(DSM)may lead to its emergence as a main new source of microplastics in the environment.Nowadays,DSMs have become a...In the context of global COVID-19 epidemic preparedness,the extensive use of disposable surgical masks(DSM)may lead to its emergence as a main new source of microplastics in the environment.Nowadays,DSMs have become a non-negligible source of plastic waste in aquatic environment,however,less research has been done on DSM after biofilm colonization in freshwater environment.The study investigated the microbial community of DSM-associated biofilms by 16S rRNA gene sequencing.Analysis of the microbial community in the middle and inner/outer layers of the DSM showed that the middle layer was different from the remaining two layers and that potential pathogens were enriched only in the middle layer of the DSM.Herein,we focused on the middle layer and explored the characterization properties and extracellular polymeric substances(EPS)components changes during biofilm formation.The results showed that the EPS components varied with the biofilm incubation time.As the formation of biofilm,the protein(PN)and polysaccharide(PS)in EPS showed an overall increasing trend,and the growth of PS was well synchronized with PN.Three fluorescent components of EPS were determined by the three-dimensional excitation emission matrix(3D-EEM),including humic acid-like,fulvic acid-like,and aromatic protein-like components.The percentage of fluorescent components varied with increasing biofilm development time and then stabilized.Fourier transform infrared spectroscopy(FTIR)characterization results elucidated the emergence of oxygen-containing functional groups during biofilm formation.Moreover,the hydrophilicity increased with biofilm development.In conclusion,the environmental behavior and ecological risks of DSM in aquatic environment deserve urgent attention in future studies.展开更多
With extensive attention being paid to the potential environmental hazards of discarded face masks,catalytic pyrolysis technologies have been proposed to realize the valorization of wastes.However,recent catalyst sele...With extensive attention being paid to the potential environmental hazards of discarded face masks,catalytic pyrolysis technologies have been proposed to realize the valorization of wastes.However,recent catalyst selection and system design have focused solely on conversion efficiency,ignoring economic cost and potential life-cycle environmental damage.Here,we propose an economic-environmental hybrid pre-assessment method to help identify catalysts and reactors with less environmental impact and high economic returns among various routes to convert discarded face masks into carbon nanotubes(CNTs)and hydrogen.In catalyst selection,it was found that a widely known Fe-Ni catalyst exhibits higher catalytic activity than a cheaper Fe catalyst,potentially increasing the economic viability of the catalytic pyrolysis system by 38%-55%.The use of this catalyst also results in a carbon reduction of 4.12-10.20kilogram CO_(2) equivalent for 1 kilogram of discarded face masks,compared with the cheaper Fe catalyst.When the price of CNTs exceeds 1.49×10^(4) USD·t^(-1),microwave-assisted pyrolysis is the optimal choice due to its superior environmental performance(in terms of its life-cycle greenhouse gas reduction potential,eutrophication potential,and human toxicity)and economic benefits.In contrast,conventional heating pyrolysis may be a more economical option due to its good stability over 43 reaction regeneration cycles,as compared with a microwave-assisted pyrolysis catalyst with a higher conversion efficiency.This study connects foundational science with ecological economics to guide emerging technologies in their research stage toward technical efficiency,economic benefits,and environmental sustainability.展开更多
Over 950 billion(about 3.8 million tons)masks have been consumed in the last four years around the world to protect human beings from COVID-19 and air pollution.However,very few of these used masks are being recycled,...Over 950 billion(about 3.8 million tons)masks have been consumed in the last four years around the world to protect human beings from COVID-19 and air pollution.However,very few of these used masks are being recycled,with the majority of them being landfilled or incinerated.To address this issue,we propose a repurposing upcycling strategy by converting these polypropylene(PP)-based waste masks to highperformance thermally conductive nanocomposites(PP@G,where G refers to graphene)with exceptional electromagnetic interference shielding property.The PP@G is fabricated by loading tannic acid onto PP fibers via electrostatic self-assembling,followed by mixing with graphene nanoplatelets(GNPs).Because this strategy enables the GNPs to form efficient thermal and electrical conduction pathways along the PP fiber surface,the PP@G shows a high thermal conductivity of 87 W m^(-1)K^(-1)and exhibits an electromagnetic interference shielding effectiveness of 88 dB(1100 dB cm^(−1)),making it potentially applicable for heat dissipation and electromagnetic shielding in advanced electronic devices.Life cycle assessment and techno-economic assessment results show that our repurposing strategy has significant advantages over existing methods in reducing environmental impacts and economic benefits.This strategy offers a facile and promising approach to upcycling/repurposing of fibrous waste plastics.展开更多
Owing to the significant increase in air pollutants and the spread of infectious diseases,it seems that the use of face masks will become an essential item in human societies.Therefore,there is a need to conduct more ...Owing to the significant increase in air pollutants and the spread of infectious diseases,it seems that the use of face masks will become an essential item in human societies.Therefore,there is a need to conduct more research to develop novel types of respirators utilizing upto-date science such as nanotechnology.In this study,we fabricated a nanocomposite fibrous filter containing modified graphene oxide(GO)and zinc oxide(ZnO)nanoparticles.This layer was used as an active filter for absorbing and removing air pollutants,such as suspended submicron particles(below 2.5 microns)and CO_(2),NO_(2),and SO_(2)gases.The synthesized nanostructures and fibrous filters were characterized by different analysis(FTIR,XRD,TGA,and FESEM),and the performance of the filters was surveyed by tests such as pressure drop,CO_(2),NO_(2),SO_(2)gas rejection,and particulate removal.The results showed that the stabilization of the modified GO and ZnO nanostructures on the fibrous filter improved the effectiveness of this filter as a mask for removing toxic particles and gases,and the filter containing nanoparticles had the best performance.展开更多
By using two PM2.5 automatic monitors,the protective effects of five common masks against PM2.5 were synchronously tested under actual ambient air conditions for a whole day. The results showed that not all masks had ...By using two PM2.5 automatic monitors,the protective effects of five common masks against PM2.5 were synchronously tested under actual ambient air conditions for a whole day. The results showed that not all masks had protective effects on PM2.5,and the protective effects of masks N95 and N90,which were designed specially for dust-proof,were superior among the five tested masks.展开更多
Notwithstanding the end of 2009 H1N1 pandemic,the threat for its revisit still persists and WHO has warned to remain vigilant.During that lime the situation was more panicky than fatal.In this article,a suggestion to ...Notwithstanding the end of 2009 H1N1 pandemic,the threat for its revisit still persists and WHO has warned to remain vigilant.During that lime the situation was more panicky than fatal.In this article,a suggestion to minimize the panic is provided by the usage of colour-coded masks and is proposed hereby as a "population segregation" approach in case of the revisit of HlNl or similar threatening respiratory viral infections.展开更多
The objective was to measure the effect of various face masks on speech recognition threshold and the word recognition score in the presence of varying background noise levels.20 normal-hearing adult subjects(a total ...The objective was to measure the effect of various face masks on speech recognition threshold and the word recognition score in the presence of varying background noise levels.20 normal-hearing adult subjects(a total of 40 ears)participated.Pure tone audiometry followed by speech recognition threshold and word recognition score at the most comfortable level in varying signal-to-noise ratios(SNR0,SNR10,and SNR15)using surgical,pleated cloth,and N95 masks.Using surgical,cloth,and N95 masks,speech recognition thresholds increased by 1.8 dB,4.4 dB,and 5.05 dB,respectively.Word recognition scores decreased by 32%without a mask,43.7%in a surgical mask,46.3%in a cloth mask,and 46.7%in N95 mask conditions,between SNR15 and SNR0.The speech recognition threshold was negatively affected with cloth and N95 masks.Surgical masks do not affect the word recognition scores at lower background noise levels.However,as the signal-to-noise ratio decreased,even the surgical,cloth,and N95 masks significantly impacted the word recognition score even in normal-hearing individuals.展开更多
Influenced by recent COVID-19,wearing face masks to block the spread of the epidemic has become the simplest and most effective way.However,after the people wear masks,thousands of tons of medical waste by used dis-po...Influenced by recent COVID-19,wearing face masks to block the spread of the epidemic has become the simplest and most effective way.However,after the people wear masks,thousands of tons of medical waste by used dis-posable masks will be generated every day in the world,causing great pressure on the environment.Herein,con-ductive polymer composites are fabricated by simple melt blending of mask fragments(mask polypropylene,short for mPP)and multi-walled carbon nanotubes(MWNTs).MWNTs were used as modifiers for composites because of their high strength and high conductivity.The crystalline structure,mechanical,electrical and thermal enhancement effect of the composites were investigated.MWNTs with high thermal stability acted the role of promoting the crystallisation of mPP by expediting the crystalline nucleation,leading to the improvement of amount for crystalline nucleus.MWNTs fibers interpenetrate with each other in mPP matrix to form conducting network.With 2.0 wt% MWNTs loading,the tensile strength and electrical conductivity of the composites were increased by 809% and 7 orders of magnitude.MWNTs fibers interpenetrate with each other in mPP matrix to form conducting network.Thus,more conducting paths were constructed to transport carriers.The findings may open a way for high value utilization of the disposable masks.展开更多
Since the fi rst cases of coronavirus disease 2019(COVID-19)caused by severe acute respiratory syndrome coro-navirus 2(SARS-CoV-2)were reported at the end of 2019,this infection has spread around the globe,becoming a ...Since the fi rst cases of coronavirus disease 2019(COVID-19)caused by severe acute respiratory syndrome coro-navirus 2(SARS-CoV-2)were reported at the end of 2019,this infection has spread around the globe,becoming a pandemic.The use of face masks and respirators is an important public health measure to reduce or prevent transmission of SARS-CoV-2.Here we discuss the hypothetical mechanisms by which exercise with face masks or respirators can induce detrimental effects on the cardiovascular system,potentially explaining adverse events such as cardiac arrhythmias and spontaneous pneumothorax.Although sudden death associated with the wearing of a face mask during running is a rare event,the risk is higher especially in those with existing cardiac comorbidities.In such cases,a mask designed specifi cally for runners with no or few side effects of oxygen defi ciency should be considered instead.展开更多
BACKGROUND Paediatric supraglottic airway devices(SGAs)are widely used in routine anaesthesia and serve as primary or back-up devices for difficult airway management.The inflatable Ambu laryngeal masks and non-inflata...BACKGROUND Paediatric supraglottic airway devices(SGAs)are widely used in routine anaesthesia and serve as primary or back-up devices for difficult airway management.The inflatable Ambu laryngeal masks and non-inflatable i-gel are two improvements of SGAs based on classic laryngeal masks.The clinical performance and safety of these two devices in paediatric patients are still unclear and warrant further investigation.AIM To perform a systematic review and meta-analysis on the clinical performance and safety of Ambu laryngeal masks and i-gel in anaesthetised paediatric patients.METHODS MEDLINE,Embase,Web of Science and Cochrane Central Register of Controlled Trials were searched from inception dates to April 2020.We identified published randomised controlled trials(RCTs)in which the intervention involved the use of Ambu laryngeal masks and i-gel in anaesthetised paediatric patients(age<18 years).We assessed the oropharyngeal leak pressure(OLP)as the primary outcome.The secondary outcomes were insertion time,success rate of insertion on the first attempt,and incidence of adverse events.RESULTS After searching for all relevant trials published up to April 2020,data from seven RCTs with a total of 667 paediatric patients(323 and 344 participants in the i-gel and Ambu groups,respectively)were evaluated.The mean OLP in anaesthetised paediatric patients was lower in the Ambu group[21.82 cmH2O for Ambu vs 23.98 cmH2O for i-gel,P=0.003,95%confidence interval(CI):-3.58 to-0.75,I2=68%,Mantel-Haenszel random model].We did not find any clear evidence of differences between the devices in terms of insertion time,success rate of insertion,and incidence of adverse events except for blood staining(risk ratio 5.86,95%CI:1.76 to 19.46,P=0.004,I2=0,fixed-effect model).CONCLUSION The i-gel airway may provide a better seal and is therefore probably more suitable than the Ambu laryngeal mask airway in anaesthetised paediatric patients.However,the evidence is insufficient to allow making firm conclusions or to guide clinical practice,owing to the small number of relevant published studies.展开更多
Several approaches to fabricate micro optical elements by use of half tone masks are studied and compared. It is shown that half tone masks employed in filtering image systems can obtain gray patterns with considerabl...Several approaches to fabricate micro optical elements by use of half tone masks are studied and compared. It is shown that half tone masks employed in filtering image systems can obtain gray patterns with considerably high precision, but it is hard to operate from the viewpoint of operation. The method using contacting lithography technology or laser ablation can be easily operated with the cost of reducing fabrication precision and the trouble of choosing appropriate materials. For all of these methods, the coding of half tone masks with corrections for the nonlinear characteristics of coding, imaging and photoresist is recommended.展开更多
In a letter to Vita Sackville-West dated 8 August 1931, eight years after Katherine Mansfield＇s death, Virginia Woolf confides that she ＂gave up＂ reading her literary rival＇s stories ＂because of their cheap sharp...In a letter to Vita Sackville-West dated 8 August 1931, eight years after Katherine Mansfield＇s death, Virginia Woolf confides that she ＂gave up＂ reading her literary rival＇s stories ＂because of their cheap sharp sentimentality＂. Woolf＇s observation invites us to question： is Mansfield a mere sentimentalist or is her characterisation technique misunderstood？ The first section of this paper demonstrates that attributing Mansfield＇ works as ＂sentimental＂ is erroneous since Mansfield＇s strategy is to change the masks of her characters within her stories, revealed in her letters and journal entries. Following the first section of this paper, I aim to explore how Mansfield extends this strategy of changing masks in daily life to her fictional characters in ＂Je ne parle pas fran^ais＂ （1918） by equipping them with different types of masks--speech and facial expressions, gender, and animality--to respond to changes in their situations and toward the characters around them. Particularly important to this exploration are Joan Riviere＇s insights into gender in her article, ＂Womanliness as Masquerade＂, Michael Goldman＇s theory of masks in acting in his The Actor＇s Freedom： Toward a Theory of Drama and Gilles Deleuze and Felix Guattari＇s concept of ＂becoming-animal＂ in KaJka.＂ Towards a Minor Literature.展开更多
Since COVID-19 was declared by the World Health Organization (WHO), wearing of protective equipment, hand washing using soap and frequent use of antiseptic solution are being applied globally to reduce the transmissio...Since COVID-19 was declared by the World Health Organization (WHO), wearing of protective equipment, hand washing using soap and frequent use of antiseptic solution are being applied globally to reduce the transmission rate. This study was intended to investigate handling of after wash waste water and masks among Tanzanian residents on the COVID-19 pandemic after it has been, declared by the World Health Organization (WHO) that, wearing of protective equipment, hand washing using soap and frequent use of antiseptic solution should be applied globally to reduce the transmission rate. The assessment of health care waste management in the facilities was conducted in all the 26 regions of Tanzania Mainland. A standardized checklist and tools were used to assess and monitor various aspects related to healthcare waste using open source software for collection (ODK). Data were analyzed using SPSS computer software. It has been indicated that before disposing the used mask, the best protocol is to spray 0.5% (5000 ppm) of chlorine disinfectant on the surface. In this study, about 46% consider used mask as normal municipal waste and 3% do not care they throw away the face masks in the street. Only 18% and 5% of reported to disposal as infectious and highly hazardous waste respectively. It is well documented that due to potential infectious disease like SARS-CoV-2, wastewater should be treated either on-site or conveyed off-site and treated in well-designed method or technology to kill the micro-organisms. The analysis revealed that majority of respondents (74.7%, 73.8%, 48.1% and 65% for healthcare center, district hospitals, regional hospitals and consultant hospitals respectively);dispose the waste in the open space. Continuous awareness creation programs about the negative impact of contaminated face masks and waste water on the health of individuals and introducing laws that can prohibit improper disposal are among the solutions that could help reduce the problem.展开更多
THE characteristically colorful Peking Opera masks emerged around 1894.A man of the Manchu ethnic group with the last name of Gui,who ardently loved Peking Opera.One day,he saw clay figurines in a temple fair,and at t...THE characteristically colorful Peking Opera masks emerged around 1894.A man of the Manchu ethnic group with the last name of Gui,who ardently loved Peking Opera.One day,he saw clay figurines in a temple fair,and at that moment an inspiration came to him to use a puddle to make a face-shaped mold.After making the mold,he dried it in the sun,and drew outlines and colored it according to the facial make-up of Peking Opera actors on the stage.For his creation,Gui became famous among Peking Opera fans in Beijing and was called“Painted face Gui”thereafter.展开更多
Corrosion control engineer: In the wilderness of the vast desert, accompanied by blowing sand, Chang Shuqiang has spent 14 of his youthful years along with the colorful paint that mirrors his splendid and sparkling li...Corrosion control engineer: In the wilderness of the vast desert, accompanied by blowing sand, Chang Shuqiang has spent 14 of his youthful years along with the colorful paint that mirrors his splendid and sparkling life. With the spray gun as his "weapon" and the brush as his "painting brush", he applies warm and anti-aging "masks" on field facilities with wisdom and effort.展开更多
The exact risk association of coronavirus disease 2019(COVID-19)for surgeons is not quantified which may be affected by their risk of exposure and individual factors.The objective of this review is to quantify the ris...The exact risk association of coronavirus disease 2019(COVID-19)for surgeons is not quantified which may be affected by their risk of exposure and individual factors.The objective of this review is to quantify the risk of COVID-19 among surgeons,and explore whether facemask can minimise the risk of COVID-19 among surgeons.A systematised review was carried out by searching MEDLINE to locate items on severe acute respiratory syndrome coronavirus 2 or COVID-19 in relation to health care workers(HCWs)especially those work in surgical specialities including surgical nurses and intensivists.Additionally,systematic reviews that assessed the effectiveness of facemask against viral respiratory infections,including COVID-19,among HCWs were identified.Data from identified articles were abstracted,synthesised and summarised.Fourteen primary studies that provided data on severe acute respiratory syndrome coronavirus 2 infection or experience among surgeons and 11 systematic reviews that provided evidence of the effectiveness of facemask(and other personal protective equipment)were summarised.Although the risk of COVID-19 could not be quantified precisely among surgeons,about 14%of HCWs including surgeons had COVID-19,there could be variations depending on settings.Facemask was found to be somewhat protective against COVID-19,but the HCWs’compliance was highly variable ranging from zero to 100%.Echoing surgical societies’guidelines we continue to recommend facemask use among surgeons to prevent COVID-19.展开更多
The outbreak of coronavirus has led to an increase in the demand for facemasks globally. Unavailability of appropriate polypropylene non-woven fabrics face masks as a result of inadequate supply to satisfy the growing...The outbreak of coronavirus has led to an increase in the demand for facemasks globally. Unavailability of appropriate polypropylene non-woven fabrics face masks as a result of inadequate supply to satisfy the growing population has brought about the manufacturing of locally fabrics masks to augment or substitute standard medical class facemasks. The study aims at analyzing airflow of these locally manufactured fabrics to determine possible means of transmitting the virus as well as establish comfort of the user of these masks. Standard polypropylene non-woven, woven and knitted fabrics were considered for the study. Air permeability test was conducted on these fabrics using Frazier Air permeability tester. Depending on the property significant variation in the textile fabrics, polypropylene non-woven is widely accepted for facial masks. Nevertheless, this study illustrates that woven and knitted fabrics have more open structures, which allow a high rate of air penetration and so may require two or three layers to prevent antimicrobial or antiviral potential.展开更多
Water is a very important natural resource and it supports all life forms on earth. It is used by humans in various ways including drinking, agriculture and for scientific research. The aim of this research was to dev...Water is a very important natural resource and it supports all life forms on earth. It is used by humans in various ways including drinking, agriculture and for scientific research. The aim of this research was to develop a routine to automatically extract water masks from RapidEye images, which could be used for further investigation such as water quality monitoring and change detection. A Python-based algorithm was therefore developed for this particular purpose. The developed routine combines three spectral indices namely Simple Ratios (SRs), Normalized Green Index (NGI) and Normalized Difference Water Index (NDWI). The two SRs are calculated between the NIR and green band, and between the NIR and red band. The NGI is calculated by rationing the green band to the sum of all bands in each image. The NDWI is calculated by differencing the green to the NIR and dividing by the sum of the green and NIR bands. The routine generates five intermediate water masks, which are spatially intersected to create a single intermediate water mask. In order to remove very small waterbodies and any remaining gaps in the intermediate water mask, morphological opening and closing were performed to generate the final water mask. This proposed algorithm was used to extract water masks from some RapidEye images. It yielded an Overall Accuracy of 95% and a mean Kappa Statistic of 0.889 using the confusion matrix approach.展开更多
The COVID-19 pandemic has led to the widespread mandatory use of personal protective equipment(PPE),including filtering face pieces(FFP).Emergency medical care providers now commonly use this equipment.
基金Supported by the Natural Science Foundation of Shandong Province(Nos.ZR2022MD115,ZR202111160067)。
文摘In the context of global COVID-19 epidemic preparedness,the extensive use of disposable surgical masks(DSM)may lead to its emergence as a main new source of microplastics in the environment.Nowadays,DSMs have become a non-negligible source of plastic waste in aquatic environment,however,less research has been done on DSM after biofilm colonization in freshwater environment.The study investigated the microbial community of DSM-associated biofilms by 16S rRNA gene sequencing.Analysis of the microbial community in the middle and inner/outer layers of the DSM showed that the middle layer was different from the remaining two layers and that potential pathogens were enriched only in the middle layer of the DSM.Herein,we focused on the middle layer and explored the characterization properties and extracellular polymeric substances(EPS)components changes during biofilm formation.The results showed that the EPS components varied with the biofilm incubation time.As the formation of biofilm,the protein(PN)and polysaccharide(PS)in EPS showed an overall increasing trend,and the growth of PS was well synchronized with PN.Three fluorescent components of EPS were determined by the three-dimensional excitation emission matrix(3D-EEM),including humic acid-like,fulvic acid-like,and aromatic protein-like components.The percentage of fluorescent components varied with increasing biofilm development time and then stabilized.Fourier transform infrared spectroscopy(FTIR)characterization results elucidated the emergence of oxygen-containing functional groups during biofilm formation.Moreover,the hydrophilicity increased with biofilm development.In conclusion,the environmental behavior and ecological risks of DSM in aquatic environment deserve urgent attention in future studies.
基金supported by the National Natural Science Foundation of China(52076099,52306257,and 72293601)。
文摘With extensive attention being paid to the potential environmental hazards of discarded face masks,catalytic pyrolysis technologies have been proposed to realize the valorization of wastes.However,recent catalyst selection and system design have focused solely on conversion efficiency,ignoring economic cost and potential life-cycle environmental damage.Here,we propose an economic-environmental hybrid pre-assessment method to help identify catalysts and reactors with less environmental impact and high economic returns among various routes to convert discarded face masks into carbon nanotubes(CNTs)and hydrogen.In catalyst selection,it was found that a widely known Fe-Ni catalyst exhibits higher catalytic activity than a cheaper Fe catalyst,potentially increasing the economic viability of the catalytic pyrolysis system by 38%-55%.The use of this catalyst also results in a carbon reduction of 4.12-10.20kilogram CO_(2) equivalent for 1 kilogram of discarded face masks,compared with the cheaper Fe catalyst.When the price of CNTs exceeds 1.49×10^(4) USD·t^(-1),microwave-assisted pyrolysis is the optimal choice due to its superior environmental performance(in terms of its life-cycle greenhouse gas reduction potential,eutrophication potential,and human toxicity)and economic benefits.In contrast,conventional heating pyrolysis may be a more economical option due to its good stability over 43 reaction regeneration cycles,as compared with a microwave-assisted pyrolysis catalyst with a higher conversion efficiency.This study connects foundational science with ecological economics to guide emerging technologies in their research stage toward technical efficiency,economic benefits,and environmental sustainability.
基金the National Key Research and Development Program of China(2023YFD2201404)the National Natural Science Foundation of China Youth Fund(No.52103072)+2 种基金Beijing Natural Science Foundation(No.2222068)5·5 Engineering Research&Innovation Team Project of Beijing Forestry University(No:BLRC2023A02)the Regional Research Collaboration(RRC)Program-“Sustainable Industry Manufacturing Planning for Long‑term Ecosystems(SIMPLE)Hub”.
文摘Over 950 billion(about 3.8 million tons)masks have been consumed in the last four years around the world to protect human beings from COVID-19 and air pollution.However,very few of these used masks are being recycled,with the majority of them being landfilled or incinerated.To address this issue,we propose a repurposing upcycling strategy by converting these polypropylene(PP)-based waste masks to highperformance thermally conductive nanocomposites(PP@G,where G refers to graphene)with exceptional electromagnetic interference shielding property.The PP@G is fabricated by loading tannic acid onto PP fibers via electrostatic self-assembling,followed by mixing with graphene nanoplatelets(GNPs).Because this strategy enables the GNPs to form efficient thermal and electrical conduction pathways along the PP fiber surface,the PP@G shows a high thermal conductivity of 87 W m^(-1)K^(-1)and exhibits an electromagnetic interference shielding effectiveness of 88 dB(1100 dB cm^(−1)),making it potentially applicable for heat dissipation and electromagnetic shielding in advanced electronic devices.Life cycle assessment and techno-economic assessment results show that our repurposing strategy has significant advantages over existing methods in reducing environmental impacts and economic benefits.This strategy offers a facile and promising approach to upcycling/repurposing of fibrous waste plastics.
文摘Owing to the significant increase in air pollutants and the spread of infectious diseases,it seems that the use of face masks will become an essential item in human societies.Therefore,there is a need to conduct more research to develop novel types of respirators utilizing upto-date science such as nanotechnology.In this study,we fabricated a nanocomposite fibrous filter containing modified graphene oxide(GO)and zinc oxide(ZnO)nanoparticles.This layer was used as an active filter for absorbing and removing air pollutants,such as suspended submicron particles(below 2.5 microns)and CO_(2),NO_(2),and SO_(2)gases.The synthesized nanostructures and fibrous filters were characterized by different analysis(FTIR,XRD,TGA,and FESEM),and the performance of the filters was surveyed by tests such as pressure drop,CO_(2),NO_(2),SO_(2)gas rejection,and particulate removal.The results showed that the stabilization of the modified GO and ZnO nanostructures on the fibrous filter improved the effectiveness of this filter as a mask for removing toxic particles and gases,and the filter containing nanoparticles had the best performance.
基金Supported by the Monitoring Scientific Research Foundation of Jiangsu Province,China in 2013(1321)
文摘By using two PM2.5 automatic monitors,the protective effects of five common masks against PM2.5 were synchronously tested under actual ambient air conditions for a whole day. The results showed that not all masks had protective effects on PM2.5,and the protective effects of masks N95 and N90,which were designed specially for dust-proof,were superior among the five tested masks.
文摘Notwithstanding the end of 2009 H1N1 pandemic,the threat for its revisit still persists and WHO has warned to remain vigilant.During that lime the situation was more panicky than fatal.In this article,a suggestion to minimize the panic is provided by the usage of colour-coded masks and is proposed hereby as a "population segregation" approach in case of the revisit of HlNl or similar threatening respiratory viral infections.
文摘The objective was to measure the effect of various face masks on speech recognition threshold and the word recognition score in the presence of varying background noise levels.20 normal-hearing adult subjects(a total of 40 ears)participated.Pure tone audiometry followed by speech recognition threshold and word recognition score at the most comfortable level in varying signal-to-noise ratios(SNR0,SNR10,and SNR15)using surgical,pleated cloth,and N95 masks.Using surgical,cloth,and N95 masks,speech recognition thresholds increased by 1.8 dB,4.4 dB,and 5.05 dB,respectively.Word recognition scores decreased by 32%without a mask,43.7%in a surgical mask,46.3%in a cloth mask,and 46.7%in N95 mask conditions,between SNR15 and SNR0.The speech recognition threshold was negatively affected with cloth and N95 masks.Surgical masks do not affect the word recognition scores at lower background noise levels.However,as the signal-to-noise ratio decreased,even the surgical,cloth,and N95 masks significantly impacted the word recognition score even in normal-hearing individuals.
基金M.Xiang and S.Dong wishes to thank the National Natural Science Foundation of China(21908086 and 51801083)Changzhou Sci&Tech Program(CJ20190035)+1 种基金Jiangsu Higher Education Institutions in China(19KJB610011)Natural Science Foundation of Jiangsu Province(BK20181044).
文摘Influenced by recent COVID-19,wearing face masks to block the spread of the epidemic has become the simplest and most effective way.However,after the people wear masks,thousands of tons of medical waste by used dis-posable masks will be generated every day in the world,causing great pressure on the environment.Herein,con-ductive polymer composites are fabricated by simple melt blending of mask fragments(mask polypropylene,short for mPP)and multi-walled carbon nanotubes(MWNTs).MWNTs were used as modifiers for composites because of their high strength and high conductivity.The crystalline structure,mechanical,electrical and thermal enhancement effect of the composites were investigated.MWNTs with high thermal stability acted the role of promoting the crystallisation of mPP by expediting the crystalline nucleation,leading to the improvement of amount for crystalline nucleus.MWNTs fibers interpenetrate with each other in mPP matrix to form conducting network.With 2.0 wt% MWNTs loading,the tensile strength and electrical conductivity of the composites were increased by 809% and 7 orders of magnitude.MWNTs fibers interpenetrate with each other in mPP matrix to form conducting network.Thus,more conducting paths were constructed to transport carriers.The findings may open a way for high value utilization of the disposable masks.
文摘Since the fi rst cases of coronavirus disease 2019(COVID-19)caused by severe acute respiratory syndrome coro-navirus 2(SARS-CoV-2)were reported at the end of 2019,this infection has spread around the globe,becoming a pandemic.The use of face masks and respirators is an important public health measure to reduce or prevent transmission of SARS-CoV-2.Here we discuss the hypothetical mechanisms by which exercise with face masks or respirators can induce detrimental effects on the cardiovascular system,potentially explaining adverse events such as cardiac arrhythmias and spontaneous pneumothorax.Although sudden death associated with the wearing of a face mask during running is a rare event,the risk is higher especially in those with existing cardiac comorbidities.In such cases,a mask designed specifi cally for runners with no or few side effects of oxygen defi ciency should be considered instead.
基金Supported by the Beijing Municipal Hospital Scientific Research Training Program,No.PX2017011。
文摘BACKGROUND Paediatric supraglottic airway devices(SGAs)are widely used in routine anaesthesia and serve as primary or back-up devices for difficult airway management.The inflatable Ambu laryngeal masks and non-inflatable i-gel are two improvements of SGAs based on classic laryngeal masks.The clinical performance and safety of these two devices in paediatric patients are still unclear and warrant further investigation.AIM To perform a systematic review and meta-analysis on the clinical performance and safety of Ambu laryngeal masks and i-gel in anaesthetised paediatric patients.METHODS MEDLINE,Embase,Web of Science and Cochrane Central Register of Controlled Trials were searched from inception dates to April 2020.We identified published randomised controlled trials(RCTs)in which the intervention involved the use of Ambu laryngeal masks and i-gel in anaesthetised paediatric patients(age<18 years).We assessed the oropharyngeal leak pressure(OLP)as the primary outcome.The secondary outcomes were insertion time,success rate of insertion on the first attempt,and incidence of adverse events.RESULTS After searching for all relevant trials published up to April 2020,data from seven RCTs with a total of 667 paediatric patients(323 and 344 participants in the i-gel and Ambu groups,respectively)were evaluated.The mean OLP in anaesthetised paediatric patients was lower in the Ambu group[21.82 cmH2O for Ambu vs 23.98 cmH2O for i-gel,P=0.003,95%confidence interval(CI):-3.58 to-0.75,I2=68%,Mantel-Haenszel random model].We did not find any clear evidence of differences between the devices in terms of insertion time,success rate of insertion,and incidence of adverse events except for blood staining(risk ratio 5.86,95%CI:1.76 to 19.46,P=0.004,I2=0,fixed-effect model).CONCLUSION The i-gel airway may provide a better seal and is therefore probably more suitable than the Ambu laryngeal mask airway in anaesthetised paediatric patients.However,the evidence is insufficient to allow making firm conclusions or to guide clinical practice,owing to the small number of relevant published studies.
基金supported by 973 Program of China under Grant No.2006CB302900part by the National Natural Science Foundation of China under Grant No.60825405 and No.60778018
文摘Several approaches to fabricate micro optical elements by use of half tone masks are studied and compared. It is shown that half tone masks employed in filtering image systems can obtain gray patterns with considerably high precision, but it is hard to operate from the viewpoint of operation. The method using contacting lithography technology or laser ablation can be easily operated with the cost of reducing fabrication precision and the trouble of choosing appropriate materials. For all of these methods, the coding of half tone masks with corrections for the nonlinear characteristics of coding, imaging and photoresist is recommended.
文摘In a letter to Vita Sackville-West dated 8 August 1931, eight years after Katherine Mansfield＇s death, Virginia Woolf confides that she ＂gave up＂ reading her literary rival＇s stories ＂because of their cheap sharp sentimentality＂. Woolf＇s observation invites us to question： is Mansfield a mere sentimentalist or is her characterisation technique misunderstood？ The first section of this paper demonstrates that attributing Mansfield＇ works as ＂sentimental＂ is erroneous since Mansfield＇s strategy is to change the masks of her characters within her stories, revealed in her letters and journal entries. Following the first section of this paper, I aim to explore how Mansfield extends this strategy of changing masks in daily life to her fictional characters in ＂Je ne parle pas fran^ais＂ （1918） by equipping them with different types of masks--speech and facial expressions, gender, and animality--to respond to changes in their situations and toward the characters around them. Particularly important to this exploration are Joan Riviere＇s insights into gender in her article, ＂Womanliness as Masquerade＂, Michael Goldman＇s theory of masks in acting in his The Actor＇s Freedom： Toward a Theory of Drama and Gilles Deleuze and Felix Guattari＇s concept of ＂becoming-animal＂ in KaJka.＂ Towards a Minor Literature.
文摘Since COVID-19 was declared by the World Health Organization (WHO), wearing of protective equipment, hand washing using soap and frequent use of antiseptic solution are being applied globally to reduce the transmission rate. This study was intended to investigate handling of after wash waste water and masks among Tanzanian residents on the COVID-19 pandemic after it has been, declared by the World Health Organization (WHO) that, wearing of protective equipment, hand washing using soap and frequent use of antiseptic solution should be applied globally to reduce the transmission rate. The assessment of health care waste management in the facilities was conducted in all the 26 regions of Tanzania Mainland. A standardized checklist and tools were used to assess and monitor various aspects related to healthcare waste using open source software for collection (ODK). Data were analyzed using SPSS computer software. It has been indicated that before disposing the used mask, the best protocol is to spray 0.5% (5000 ppm) of chlorine disinfectant on the surface. In this study, about 46% consider used mask as normal municipal waste and 3% do not care they throw away the face masks in the street. Only 18% and 5% of reported to disposal as infectious and highly hazardous waste respectively. It is well documented that due to potential infectious disease like SARS-CoV-2, wastewater should be treated either on-site or conveyed off-site and treated in well-designed method or technology to kill the micro-organisms. The analysis revealed that majority of respondents (74.7%, 73.8%, 48.1% and 65% for healthcare center, district hospitals, regional hospitals and consultant hospitals respectively);dispose the waste in the open space. Continuous awareness creation programs about the negative impact of contaminated face masks and waste water on the health of individuals and introducing laws that can prohibit improper disposal are among the solutions that could help reduce the problem.
文摘THE characteristically colorful Peking Opera masks emerged around 1894.A man of the Manchu ethnic group with the last name of Gui,who ardently loved Peking Opera.One day,he saw clay figurines in a temple fair,and at that moment an inspiration came to him to use a puddle to make a face-shaped mold.After making the mold,he dried it in the sun,and drew outlines and colored it according to the facial make-up of Peking Opera actors on the stage.For his creation,Gui became famous among Peking Opera fans in Beijing and was called“Painted face Gui”thereafter.
文摘Corrosion control engineer: In the wilderness of the vast desert, accompanied by blowing sand, Chang Shuqiang has spent 14 of his youthful years along with the colorful paint that mirrors his splendid and sparkling life. With the spray gun as his "weapon" and the brush as his "painting brush", he applies warm and anti-aging "masks" on field facilities with wisdom and effort.
文摘The exact risk association of coronavirus disease 2019(COVID-19)for surgeons is not quantified which may be affected by their risk of exposure and individual factors.The objective of this review is to quantify the risk of COVID-19 among surgeons,and explore whether facemask can minimise the risk of COVID-19 among surgeons.A systematised review was carried out by searching MEDLINE to locate items on severe acute respiratory syndrome coronavirus 2 or COVID-19 in relation to health care workers(HCWs)especially those work in surgical specialities including surgical nurses and intensivists.Additionally,systematic reviews that assessed the effectiveness of facemask against viral respiratory infections,including COVID-19,among HCWs were identified.Data from identified articles were abstracted,synthesised and summarised.Fourteen primary studies that provided data on severe acute respiratory syndrome coronavirus 2 infection or experience among surgeons and 11 systematic reviews that provided evidence of the effectiveness of facemask(and other personal protective equipment)were summarised.Although the risk of COVID-19 could not be quantified precisely among surgeons,about 14%of HCWs including surgeons had COVID-19,there could be variations depending on settings.Facemask was found to be somewhat protective against COVID-19,but the HCWs’compliance was highly variable ranging from zero to 100%.Echoing surgical societies’guidelines we continue to recommend facemask use among surgeons to prevent COVID-19.
文摘The outbreak of coronavirus has led to an increase in the demand for facemasks globally. Unavailability of appropriate polypropylene non-woven fabrics face masks as a result of inadequate supply to satisfy the growing population has brought about the manufacturing of locally fabrics masks to augment or substitute standard medical class facemasks. The study aims at analyzing airflow of these locally manufactured fabrics to determine possible means of transmitting the virus as well as establish comfort of the user of these masks. Standard polypropylene non-woven, woven and knitted fabrics were considered for the study. Air permeability test was conducted on these fabrics using Frazier Air permeability tester. Depending on the property significant variation in the textile fabrics, polypropylene non-woven is widely accepted for facial masks. Nevertheless, this study illustrates that woven and knitted fabrics have more open structures, which allow a high rate of air penetration and so may require two or three layers to prevent antimicrobial or antiviral potential.
文摘Water is a very important natural resource and it supports all life forms on earth. It is used by humans in various ways including drinking, agriculture and for scientific research. The aim of this research was to develop a routine to automatically extract water masks from RapidEye images, which could be used for further investigation such as water quality monitoring and change detection. A Python-based algorithm was therefore developed for this particular purpose. The developed routine combines three spectral indices namely Simple Ratios (SRs), Normalized Green Index (NGI) and Normalized Difference Water Index (NDWI). The two SRs are calculated between the NIR and green band, and between the NIR and red band. The NGI is calculated by rationing the green band to the sum of all bands in each image. The NDWI is calculated by differencing the green to the NIR and dividing by the sum of the green and NIR bands. The routine generates five intermediate water masks, which are spatially intersected to create a single intermediate water mask. In order to remove very small waterbodies and any remaining gaps in the intermediate water mask, morphological opening and closing were performed to generate the final water mask. This proposed algorithm was used to extract water masks from some RapidEye images. It yielded an Overall Accuracy of 95% and a mean Kappa Statistic of 0.889 using the confusion matrix approach.
基金funded by the Medical Scientific Fund of the Mayor of the City of Vienna(Grant#COVID054)。
文摘The COVID-19 pandemic has led to the widespread mandatory use of personal protective equipment(PPE),including filtering face pieces(FFP).Emergency medical care providers now commonly use this equipment.
