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1.
J Chromatogr A ; 1627: 461402, 2020 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-32823107

RESUMO

Surfactants are used in various applications: cosmetics, pharmaceuticals, petrochemicals, environmental, etc. Many of these compounds are polydisperse, and because of this intrinsic polydispersity, it is essential to have a universal detector with a uniform response to quantify them in a simple way. Indeed, Charged Aerosol Detector (CAD) was presented as a universal detector with a uniform response. Thus, in the present study, the CAD response, in a High-Performance Liquid Chromatography - CAD configuration (HPLCCAD), was evaluated using purified alcohol ethoxylated surfactants. A semi-preparative liquid chromatography step using a Hydrophilic interaction chromatography (HILIC) bare silica column (150 mm, 4.6 mm, 2.6 µm) was implemented to prepare eleven homologues of BrijC10, a nonionic surfactant. These homologues differed only by the number of ethylene oxide units. BrijC10 homologues were analyzed by HPLCCAD, using a HILIC bare silica column (150 mm, 2.1 mm, 2.6 µm) to determine the HPLCCAD response factors of purified homologues. From the calibration curves (from 100 to 500 mg.kg-1), their response factors were estimated: differences in response factors were observed and a maximum difference in response factors of 3.6 was obtained. Thus, it could be concluded that CAD hyphenated to HILIC separation did not present a uniform response for this homologue's distribution.


Assuntos
Aerossóis/química , Cromatografia Líquida de Alta Pressão/métodos , Calibragem , Cromatografia Líquida de Alta Pressão/normas , Etil-Éteres/química , Interações Hidrofóbicas e Hidrofílicas , Dióxido de Silício/química , Tensoativos/química
2.
PLoS One ; 15(8): e0236063, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32756567

RESUMO

The primary objective of this research was to extract the essential information needed for setting atomization break up models, specifically, the Linear Instability Sheet Atomization (LISA) breakup model, and alternative hollow cone models. A secondary objective was to gain visualization and insight into the atomization break up mechanism caused by the effects of viscosity and surface tension on primary break-up, sheet disintegration, ligament and droplet formation. High speed imaging was used to capture the near-nozzle characteristics for water and drug formulations. This demonstrated more rapid atomization for lower viscosities. Image processing was used to analyze the near-nozzle spray characteristics during the primary break-up of the liquid sheet into ligament formation. Edges of the liquid sheet, spray break-up length, break-up radius, cone angle and dispersion angle were obtained. Spray characteristics pertinent for primary breakup modelling were determined from high speed imaging of multiple spray actuations. The results have established input data for computational modelling involving parametrical analysis of nasal drug delivery.


Assuntos
Sprays Nasais , Nebulizadores e Vaporizadores , Administração Intranasal , Aerossóis/química , Composição de Medicamentos , Sistemas de Liberação de Medicamentos/instrumentação , Desenho de Equipamento , Humanos , Tamanho da Partícula , Tensão Superficial , Viscosidade , Água/química
3.
J Cataract Refract Surg ; 46(9): 1297-1301, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32649436

RESUMO

PURPOSE: To study propensity of aerosol and droplet generation during phacoemulsification using high-speed shadowgraphy and quantify its spread amid COVID-19 pandemic. SETTING: Aerosol and droplet quantification laboratory. DESIGN: Laboratory study. METHODS: In an experimental set-up, phacoemulsification was performed on enucleated goat eyes and cadaveric human corneoscleral rims mounted on an artificial anterior chamber. Standard settings for sculpt and quadrant removal mode were used on Visalis 100 (Carl Zeiss Meditec AG). Microincision and standard phacoemulsification were performed using titanium straight tips (2.2 mm and 2.8 mm in diameter). The main wound incisions were titrated equal to and larger than the sleeve size. High-speed shadowgraphy technique was used to detect the possible generation of any droplets and aerosols. The visualization and quantification of size of the aerosols and droplets along with calculation of their spread were the main outcome measures. RESULTS: In longitudinal phacoemulsification using a peristaltic pump device with a straight tip, no aerosol generation was seen in a closed chamber. In larger wounds, there was a slow leak at the main wound. The atomization of balanced salt solution was observed only when the phacoemulsification tip was completely exposed next to the ocular surface. Under this condition, the nominal size of the droplet was approximately 50 µm, and the maximum calculated spread was 1.3 m. CONCLUSIONS: There was no visible aerosol generation during microincision or standard phacoemulsification. Phacoemulsification is safe to perform in the COVID-19 era by taking adequate precautions against other modes of transmission.


Assuntos
Aerossóis/química , Betacoronavirus , Infecções por Coronavirus/transmissão , Transmissão de Doença Infecciosa do Paciente para o Profissional/prevenção & controle , Microbolhas , Facoemulsificação/métodos , Pneumonia Viral/transmissão , Animais , Infecções por Coronavirus/epidemiologia , Diagnóstico por Imagem/métodos , Cabras , Modelos Animais , Oftalmologistas , Pandemias , Pneumonia Viral/epidemiologia
4.
J Chromatogr A ; 1625: 461336, 2020 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-32709360

RESUMO

Thermal desorption aerosol gas chromatography mass spectrometry is capable of online measuring speciated organics in atmospheric aerosols. Compared to the one-dimensional gas chromatography, comprehensive two-dimensional gas chromatography increases the resolution and the sensitivity, mitigates the unresolved complex mixture and co-elution occurred in one-dimensional gas chromatography. In this study, we report a quartz filter-based thermal desorption aerosol comprehensive two-dimensional gas chromatography mass spectrometry (2D-Q-TAG). It combines a solid-state thermal modulator with a quartz filter-based thermal desorption aerosol gas chromatography mass spectrometry. The solid-state thermal modulator conducts modulation independently from the chromatographic oven without using cryogens or compressed air, which makes the system readily adaptive for field measurement. The 2D-Q-TAG was evaluated using C7-C40 n-alkanes and 16 polycyclic aromatic hydrocarbons (PAHs). It has low limits of detection from 0.001 to 0.104 ng. The instrument was then deployed to measure atmospheric PM2.5 (particulate matter with an equivalent aerodynamic diameter  ≤  2.5 µm) in urban Beijing. It allows in-situ detection of speciated organics in atmospheric aerosols with hourly time resolution. Organic classes including alkanes, furanones, alcohols, aldehydes, ketones, acids, PAHs, oxy-PAHs, and alkyl-naphthalenes were well separated and detected. The total mass concentration of n-alkanes ranged from 122.1 to 629.9 ng/m3. Diurnal variation of n-alkanes was captured due to the high time resolution of the instrument.


Assuntos
Aerossóis/análise , Cromatografia Gasosa-Espectrometria de Massas/métodos , Compostos Orgânicos/análise , Temperatura , Aerossóis/química , Alcanos/análise , Atmosfera/química , Limite de Detecção , Material Particulado/análise , Hidrocarbonetos Policíclicos Aromáticos/análise , Padrões de Referência , Fatores de Tempo
5.
Emerg Microbes Infect ; 9(1): 1415-1417, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: covidwho-526750

RESUMO

SARS-CoV-2, the causative agent of the COVID-19 pandemic, may be transmitted via airborne droplets or contact with surfaces onto which droplets have deposited. In this study, the ability of SARS-CoV-2 to survive in the dark, at two different relative humidity values and within artificial saliva, a clinically relevant matrix, was investigated. SARS-CoV-2 was found to be stable, in the dark, in a dynamic small particle aerosol under the four experimental conditions we tested and viable virus could still be detected after 90 minutes. The decay rate and half-life was determined and decay rates ranged from 0.4 to 2.27 % per minute and the half lives ranged from 30 to 177 minutes for the different conditions. This information can be used for advice and modelling and potential mitigation strategies.


Assuntos
Aerossóis/química , Betacoronavirus/crescimento & desenvolvimento , Infecções por Coronavirus/virologia , Meios de Cultura/química , Pneumonia Viral/virologia , Saliva Artificial/química , Salvia/virologia , Microbiologia do Ar , Betacoronavirus/química , Betacoronavirus/genética , Betacoronavirus/efeitos da radiação , Infecções por Coronavirus/transmissão , Escuridão , Humanos , Umidade , Cinética , Pandemias , Pneumonia Viral/transmissão
6.
PLoS One ; 15(6): e0234189, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32497139

RESUMO

BACKGROUND: Electronic nicotine delivery systems (ENDS; e-cigarettes), consisting of a battery, heating element and e-liquid, have evolved significantly with wide variation in design, components, operating powers, and chemical constituents. Generated aerosols have been reported to contain potentially toxic substances. We conducted a systematic review to assess what is known about the presence of toxicants in ENDS aerosols in order to inform how system design could mitigate risk. METHODS: Articles reporting on or evaluating design characteristics of ENDS and aerosol constituents were included and summarized. RESULTS: The search identified 2,305 articles, of which 92 were included after full-text review. Findings were grouped into 6 major categories of potentially harmful chemicals: carbonyls, volatile organic chemicals, trace elements, reactive oxygen species and free radicals, polycyclic aromatic hydrocarbons, and tobacco-specific nitrosamines. In general, higher concentrations of aerosol toxicants are associated with increased power or voltage. Aerosol toxicants are also associated with e-liquid flavoring agents existing as primary ingredients or as products of thermal degradation. CONCLUSIONS: Improved ENDS design can reduce toxicant levels. Additional research is needed to develop a framework for optimizing system characteristics to minimize exposure, especially with respect to heating power and e-liquids. Both manufacturers and regulatory agencies have roles in reducing toxicants and potential health risks from ENDS.


Assuntos
Aerossóis/toxicidade , Sistemas Eletrônicos de Liberação de Nicotina , Aerossóis/química , Humanos
7.
ACS Nano ; 14(7): 9188-9200, 2020 07 28.
Artigo em Inglês | MEDLINE | ID: mdl-32584542

RESUMO

Filtration efficiency (FE), differential pressure (ΔP), quality factor (QF), and construction parameters were measured for 32 cloth materials (14 cotton, 1 wool, 9 synthetic, 4 synthetic blends, and 4 synthetic/cotton blends) used in cloth masks intended for protection from the SARS-CoV-2 virus (diameter 100 ± 10 nm). Seven polypropylene-based fiber filter materials were also measured including surgical masks and N95 respirators. Additional measurements were performed on both multilayered and mixed-material samples of natural, synthetic, or natural-synthetic blends to mimic cloth mask construction methods. Materials were microimaged and tested against size selected NaCl aerosol with particle mobility diameters between 50 and 825 nm. Three of the top five best performing samples were woven 100% cotton with high to moderate yarn counts, and the other two were woven synthetics of moderate yarn counts. In contrast to recently published studies, samples utilizing mixed materials did not exhibit a significant difference in the measured FE when compared to the product of the individual FE for the components. The FE and ΔP increased monotonically with the number of cloth layers for a lightweight flannel, suggesting that multilayered cloth masks may offer increased protection from nanometer-sized aerosol with a maximum FE dictated by breathability (i.e., ΔP).


Assuntos
Infecções por Coronavirus/prevenção & controle , Máscaras/normas , Pandemias/prevenção & controle , Equipamento de Proteção Individual/normas , Pneumonia Viral/prevenção & controle , Dispositivos de Proteção Respiratória/normas , Têxteis/normas , Aerossóis/química , Betacoronavirus/patogenicidade , Filtração , Humanos , Máscaras/virologia , Nanopartículas/química , Nanopartículas/virologia , Equipamento de Proteção Individual/virologia , Dispositivos de Proteção Respiratória/virologia , Têxteis/efeitos adversos , Têxteis/virologia
8.
Emerg Microbes Infect ; 9(1): 1415-1417, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32496967

RESUMO

SARS-CoV-2, the causative agent of the COVID-19 pandemic, may be transmitted via airborne droplets or contact with surfaces onto which droplets have deposited. In this study, the ability of SARS-CoV-2 to survive in the dark, at two different relative humidity values and within artificial saliva, a clinically relevant matrix, was investigated. SARS-CoV-2 was found to be stable, in the dark, in a dynamic small particle aerosol under the four experimental conditions we tested and viable virus could still be detected after 90 minutes. The decay rate and half-life was determined and decay rates ranged from 0.4 to 2.27 % per minute and the half lives ranged from 30 to 177 minutes for the different conditions. This information can be used for advice and modelling and potential mitigation strategies.


Assuntos
Aerossóis/química , Betacoronavirus/crescimento & desenvolvimento , Infecções por Coronavirus/virologia , Meios de Cultura/química , Pneumonia Viral/virologia , Saliva Artificial/química , Salvia/virologia , Microbiologia do Ar , Betacoronavirus/química , Betacoronavirus/genética , Betacoronavirus/efeitos da radiação , Infecções por Coronavirus/transmissão , Escuridão , Humanos , Umidade , Cinética , Pandemias , Pneumonia Viral/transmissão
9.
AAPS PharmSciTech ; 21(5): 158, 2020 May 26.
Artigo em Inglês | MEDLINE | ID: mdl-32458106

RESUMO

The relationship between the geometric particle size distribution (GPSD) and the aerodynamic particle size distribution (APSD) of commercial solution and suspension metered-dose inhaler (MDI) formulations was assessed to clarify the use of GPSD to estimate the APSD. The size distribution of particles discharged from four suspension and four solution MDIs was measured using the Inas®100 light-scattering spectrometer and a Next Generation Impactor. The conversion factor was calculated by measuring the GPSD and APSD of MDIs. The morphology and physical properties of MDIs were studied using scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). Six of the eight MDIs showed similar conversion factor profiles, irrespective of their composition and formulation types. Applying the conversion factor obtained from one of the six MDIs resulted in a particle size distribution comparable to each APSD except for some formulations. The two other solution MDIs, which contained citric acid, had much higher and variable conversion factors. SEM images and DSC scans of the solids obtained by nebulization of the solutions containing beclomethasone and/or citric acid showed the formation of a paste-like amorphous solid. These results indicated that APSD of solution and suspension MDIs that form rigid particles may be estimated by using the conversion factor and GPSD. Contrarily, the estimation is more difficult in formulations that tend to lose the particle structure during the measurement.


Assuntos
Inaladores Dosimetrados , Tamanho da Partícula , Administração por Inalação , Aerossóis/química , Beclometasona/química , Nebulizadores e Vaporizadores , Soluções , Suspensões
10.
Paediatr Anaesth ; 30(8): 900-904, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32464695

RESUMO

INTRODUCTION: As the pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 or COVID-19) has impacted hospital routines in recent weeks, recommendations to reduce healthcare worker infections are being developed. METHODS: We report preliminary experience with the efficacy of an enclosure with augmented airflow to decrease the risk of exposure to aerosolized pathogens during airway management including endotracheal intubation. A particle generator was used to test the efficacy of the reduction of aerosolized particles by measuring their concentration within the enclosure and in the environment. RESULTS: No reduction in the concentration of aerosolized particles was noted with the enclosure flap open, whether the interior suction was on or off. However, with the enclosure closed and no augmented airflow (suction off), the particle concentration decreased to 1.2% of baseline. The concentration decreased even further, to 0.8% of baseline with the enclosure closed with augmented airflow (suction on). DISCUSSION: Aerosolized particulate contamination in the operating room can be decreased using a clear plastic enclosure with minimal openings and augmented airflow. This may serve to decrease the exposure of healthcare providers to aerosolized pathogens.


Assuntos
Aerossóis/química , Manuseio das Vias Aéreas/métodos , Betacoronavirus , Infecções por Coronavirus/prevenção & controle , Intubação Intratraqueal/métodos , Pandemias/prevenção & controle , Pneumonia Viral/prevenção & controle , Anestesia por Inalação/métodos , Humanos , Material Particulado , Ventilação Pulmonar , Sucção
11.
ACS Nano ; 14(5): 6339-6347, 2020 May 26.
Artigo em Inglês | MEDLINE | ID: covidwho-115796

RESUMO

The emergence of a pandemic affecting the respiratory system can result in a significant demand for face masks. This includes the use of cloth masks by large sections of the public, as can be seen during the current global spread of COVID-19. However, there is limited knowledge available on the performance of various commonly available fabrics used in cloth masks. Importantly, there is a need to evaluate filtration efficiencies as a function of aerosol particulate sizes in the 10 nm to 10 µm range, which is particularly relevant for respiratory virus transmission. We have carried out these studies for several common fabrics including cotton, silk, chiffon, flannel, various synthetics, and their combinations. Although the filtration efficiencies for various fabrics when a single layer was used ranged from 5 to 80% and 5 to 95% for particle sizes of <300 nm and >300 nm, respectively, the efficiencies improved when multiple layers were used and when using a specific combination of different fabrics. Filtration efficiencies of the hybrids (such as cotton-silk, cotton-chiffon, cotton-flannel) was >80% (for particles <300 nm) and >90% (for particles >300 nm). We speculate that the enhanced performance of the hybrids is likely due to the combined effect of mechanical and electrostatic-based filtration. Cotton, the most widely used material for cloth masks performs better at higher weave densities (i.e., thread count) and can make a significant difference in filtration efficiencies. Our studies also imply that gaps (as caused by an improper fit of the mask) can result in over a 60% decrease in the filtration efficiency, implying the need for future cloth mask design studies to take into account issues of "fit" and leakage, while allowing the exhaled air to vent efficiently. Overall, we find that combinations of various commonly available fabrics used in cloth masks can potentially provide significant protection against the transmission of aerosol particles.


Assuntos
Aerossóis/química , Filtração/normas , Máscaras/normas , Dispositivos de Proteção Respiratória/normas , Têxteis/normas , Absorção Fisico-Química , Eletricidade Estática , Têxteis/classificação
12.
ACS Nano ; 14(5): 6213-6221, 2020 05 26.
Artigo em Inglês | MEDLINE | ID: covidwho-115548

RESUMO

The 2019 coronavirus outbreak (COVID-19) is affecting over 210 countries and territories, and it is spreading mainly by respiratory droplets. The use of disposable surgical masks is common for patients, doctors, and even the general public in highly risky areas. However, the current surgical masks cannot self-sterilize in order to reuse or be recycled for other applications. The resulting high economic and environmental costs are further damaging societies worldwide. Herein, we reported a unique method for functionalizing commercially available surgical masks with outstanding self-cleaning and photothermal properties. A dual-mode laser-induced forward transfer method was developed for depositing few-layer graphene onto low-melting temperature nonwoven masks. Superhydrophobic states were observed on the treated masks' surfaces, which can cause the incoming aqueous droplets to bounce off. Under sunlight illumination, the surface temperature of the functional mask can quickly increase to over 80 °C, making the masks reusable after sunlight sterilization. In addition, this graphene-coated mask can be recycled directly for use in solar-driven desalination with outstanding salt-rejection performance for long-term use. These roll-to-roll production-line-compatible masks can provide us with better protection against this severe virus. The environment can also benefit from the direct recycling of these masks, which can be used for desalinating seawater.


Assuntos
Aerossóis/química , Grafite/química , Máscaras/normas , Dispositivos de Proteção Respiratória/normas , Absorção de Radiação , Desinfecção/métodos , Filtração , Temperatura Alta , Interações Hidrofóbicas e Hidrofílicas , Luz , Máscaras/virologia , Dispositivos de Proteção Respiratória/virologia , Condutividade Térmica
13.
ACS Nano ; 14(5): 6213-6221, 2020 05 26.
Artigo em Inglês | MEDLINE | ID: mdl-32329600

RESUMO

The 2019 coronavirus outbreak (COVID-19) is affecting over 210 countries and territories, and it is spreading mainly by respiratory droplets. The use of disposable surgical masks is common for patients, doctors, and even the general public in highly risky areas. However, the current surgical masks cannot self-sterilize in order to reuse or be recycled for other applications. The resulting high economic and environmental costs are further damaging societies worldwide. Herein, we reported a unique method for functionalizing commercially available surgical masks with outstanding self-cleaning and photothermal properties. A dual-mode laser-induced forward transfer method was developed for depositing few-layer graphene onto low-melting temperature nonwoven masks. Superhydrophobic states were observed on the treated masks' surfaces, which can cause the incoming aqueous droplets to bounce off. Under sunlight illumination, the surface temperature of the functional mask can quickly increase to over 80 °C, making the masks reusable after sunlight sterilization. In addition, this graphene-coated mask can be recycled directly for use in solar-driven desalination with outstanding salt-rejection performance for long-term use. These roll-to-roll production-line-compatible masks can provide us with better protection against this severe virus. The environment can also benefit from the direct recycling of these masks, which can be used for desalinating seawater.


Assuntos
Aerossóis/química , Grafite/química , Máscaras/normas , Dispositivos de Proteção Respiratória/normas , Absorção de Radiação , Desinfecção/métodos , Filtração , Temperatura Alta , Interações Hidrofóbicas e Hidrofílicas , Luz , Máscaras/virologia , Dispositivos de Proteção Respiratória/virologia , Condutividade Térmica
14.
Nature ; 582(7813): 557-560, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32340022

RESUMO

The ongoing outbreak of coronavirus disease 2019 (COVID-19) has spread rapidly on a global scale. Although it is clear that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is transmitted through human respiratory droplets and direct contact, the potential for aerosol transmission is poorly understood1-3. Here we investigated the aerodynamic nature of SARS-CoV-2 by measuring viral RNA in aerosols in different areas of two Wuhan hospitals during the outbreak of COVID-19 in February and March 2020. The concentration of SARS-CoV-2 RNA in aerosols that was detected in isolation wards and ventilated patient rooms was very low, but it was higher in the toilet areas used by the patients. Levels of airborne SARS-CoV-2 RNA in the most public areas was undetectable, except in two areas that were prone to crowding; this increase was possibly due to individuals infected with SARS-CoV-2 in the crowd. We found that some medical staff areas initially had high concentrations of viral RNA with aerosol size distributions that showed peaks in the submicrometre and/or supermicrometre regions; however, these levels were reduced to undetectable levels after implementation of rigorous sanitization procedures. Although we have not established the infectivity of the virus detected in these hospital areas, we propose that SARS-CoV-2 may have the potential to be transmitted through aerosols. Our results indicate that room ventilation, open space, sanitization of protective apparel, and proper use and disinfection of toilet areas can effectively limit the concentration of SARS-CoV-2 RNA in aerosols. Future work should explore the infectivity of aerosolized virus.


Assuntos
Aerossóis/análise , Aerossóis/química , Aparelho Sanitário , Betacoronavirus/isolamento & purificação , Infecções por Coronavirus/virologia , Hospitais , Pneumonia Viral/virologia , Local de Trabalho , Betacoronavirus/genética , China/epidemiologia , Infecções por Coronavirus/epidemiologia , Infecções por Coronavirus/prevenção & controle , Infecções por Coronavirus/transmissão , Aglomeração , Desinfecção , Humanos , Unidades de Terapia Intensiva , Máscaras , Corpo Clínico , Pandemias/prevenção & controle , Pacientes/estatística & dados numéricos , Pneumonia Viral/epidemiologia , Pneumonia Viral/prevenção & controle , Pneumonia Viral/transmissão , RNA Viral/análise , Isolamento Social , Ventilação
15.
ACS Nano ; 14(5): 6339-6347, 2020 May 26.
Artigo em Inglês | MEDLINE | ID: mdl-32329337

RESUMO

The emergence of a pandemic affecting the respiratory system can result in a significant demand for face masks. This includes the use of cloth masks by large sections of the public, as can be seen during the current global spread of COVID-19. However, there is limited knowledge available on the performance of various commonly available fabrics used in cloth masks. Importantly, there is a need to evaluate filtration efficiencies as a function of aerosol particulate sizes in the 10 nm to 10 µm range, which is particularly relevant for respiratory virus transmission. We have carried out these studies for several common fabrics including cotton, silk, chiffon, flannel, various synthetics, and their combinations. Although the filtration efficiencies for various fabrics when a single layer was used ranged from 5 to 80% and 5 to 95% for particle sizes of <300 nm and >300 nm, respectively, the efficiencies improved when multiple layers were used and when using a specific combination of different fabrics. Filtration efficiencies of the hybrids (such as cotton-silk, cotton-chiffon, cotton-flannel) was >80% (for particles <300 nm) and >90% (for particles >300 nm). We speculate that the enhanced performance of the hybrids is likely due to the combined effect of mechanical and electrostatic-based filtration. Cotton, the most widely used material for cloth masks performs better at higher weave densities (i.e., thread count) and can make a significant difference in filtration efficiencies. Our studies also imply that gaps (as caused by an improper fit of the mask) can result in over a 60% decrease in the filtration efficiency, implying the need for future cloth mask design studies to take into account issues of "fit" and leakage, while allowing the exhaled air to vent efficiently. Overall, we find that combinations of various commonly available fabrics used in cloth masks can potentially provide significant protection against the transmission of aerosol particles.


Assuntos
Aerossóis/química , Filtração/normas , Máscaras/normas , Dispositivos de Proteção Respiratória/normas , Têxteis/normas , Absorção Fisico-Química , Eletricidade Estática , Têxteis/classificação
16.
Chemosphere ; 249: 126258, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32213391

RESUMO

Secondary Organic aerosols (SOA) are important components of PM 2.5. In order to control the heavy haze pollution, it is essential to find out the contributions of main SOA precursors. Nowadays, the tracer-based method has been widely used in analyzing the contributions of the precursors to SOA. However, it is not well known that whether the SOA tracers can be oxidized or how the instability of the SOA tracers would influence the accuracy of the tracer-based method for source apportionment. In this paper, the heterogeneous oxidation experiments of SOA tracers produced from isoprene and toluene as well as their mixtures under different conditions were conducted in a 2 m3 indoor chamber. The relative rate constants approach was used to determine the effective rate constants of the ozone reactions of the tracers. Concentrations of 2-Methyl Erythritol, a tracer of isoprene SOA, and 2, 3-Dihydroxy-4-oxopentanoic Acid, a tracer of toluene SOA, were analyzed using GC-MS. The effects of different seed aerosols and initial VOC0/NO on the heterogeneous oxidation of the tracers were investigated. The effects of co-existing components in the SOA produced from the mixture of isoprene and toluene on the heterogeneous oxidation of the tracers by ozone were also studied.


Assuntos
Aerossóis/química , Butadienos/química , Hemiterpenos/química , Ozônio/química , Tolueno/química , Aerossóis/análise , Poluentes Atmosféricos/análise , Oxirredução
17.
Cell Physiol Biochem ; 54(2): 230-251, 2020 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-32153152

RESUMO

BACKGROUND/AIMS: Adverse effects of cigarette smoke on health are widely known. Heating rather than combusting tobacco is one of strategies to reduce the formation of toxicants. The sensitive nature of mitochondrial dynamics makes the mitochondria an early indicator of cellular stress. For this reason, we studied the morphology and dynamics of the mitochondrial network in human bronchial epithelial cells (BEAS-2B) exposed to total particulate matter (TPM) generated from 3R4F reference cigarette smoke and from aerosol from a new candidate modified risk tobacco product, the Tobacco Heating System (THS 2.2). METHODS: Cells were subjected to short (1 week) and chronic (12 weeks) exposure to a low (7.5 µg/mL) concentration of 3R4F TPM and low (7.5 µg/mL), medium (37.5 µg/mL), and high (150 µg/mL) concentrations of TPM from THS 2.2. Confocal microscopy was applied to assess cellular and mitochondrial morphology. Cytosolic Ca2+ levels, mitochondrial membrane potential and mitochondrial mass were measured with appropriate fluorescent probes on laser scanning cytometer. The levels of proteins regulating mitochondrial dynamics and biogenesis were determined by Western blot. RESULTS: In BEAS-2B cells exposed for one week to the low concentration of 3R4F TPM and the high concentration of THS 2.2 TPM we observed clear changes in cell morphology, mitochondrial network fragmentation, altered levels of mitochondrial fusion and fission proteins and decreased biogenesis markers. Also cellular proliferation was slowed down. Upon chronic exposure (12 weeks) many parameters were affected in the opposite way comparing to short exposure. We observed strong increase of NRF2 protein level, reorganization of mitochondrial network and activation of the mitochondrial biogenesis process. CONCLUSION: Comparison of the effects of TPMs from 3R4F and from THS 2.2 revealed, that similar extent of alterations in mitochondrial dynamics and biogenesis is observed at 7.5 µg/mL of 3R4F TPM and 150 µg/mL of THS 2.2 TPM. 7 days exposure to the investigated components of cigarette smoke evoke mitochondrial stress, while upon chronic, 12 weeks exposure the hallmarks of cellular adaptation to the stressor were visible. The results also suggest that mitochondrial stress signaling is involved in the process of cellular adaptation under conditions of chronic stress caused by 3R4F and high concentration of THS 2.2.


Assuntos
Aerossóis/química , Mitocôndrias/metabolismo , Dinâmica Mitocondrial/efeitos dos fármacos , Material Particulado/toxicidade , Cálcio/metabolismo , Linhagem Celular , Corantes Fluorescentes/química , Humanos , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Microscopia Confocal , Mitocôndrias/efeitos dos fármacos , Material Particulado/química , Fumaça/efeitos adversos , Fatores de Tempo , Produtos do Tabaco/análise
18.
Chemosphere ; 252: 126456, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32182508

RESUMO

Submicron sea spray aerosol (SSA) particles play an essential role in atmospheric chemical processes and the Earth's radiative balance. In this study, different combinations of NaCl, MgSO4, malonic acid (MA), d-fructose and sodium malonate were used to explore the effect of MA on submicron SSA generation. SSA particles were produced at room temperature by bubble bursting from an adjustable home-built SSA generator with sintered glass filters. We found that MA could promote the generation of SSA particles and make the geometric mean diameter (GMD) to decrease for MA concentrations ranging between 8 and 32 mM and then, to increase for MA concentrations in the range of 64-160 mM. d-fructose could improve the generation of SSA with increasing GMD. Interestingly, sodium malonate could significantly enhance the production of SSA, with the change of morphology. Besides, different parameters including flow rate, underwater depth, pore size and size span of sintered glass filter and salinity of water were tested to obtain the characterization of our self-made adjustable SSA generator. Three modes could be found among different SSA generation methods, and they exhibited an obvious accumulation mode around 100 nm. The SSA generation under different conditions was compared with oceanic measurements from the literature, which showed that the sintered glass filter has advantages in generating submicron SSA from film drops.


Assuntos
Aerossóis/química , Água do Mar/química , Modelos Químicos , Oceanos e Mares , Sódio , Cloreto de Sódio/química , Água
19.
Chemosphere ; 252: 126573, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32220725

RESUMO

The interaction-based oxidative potential (OPint) represents the prediction of binary mixture effects distinguishing from linear additivity by including information on binary mixtures among PM components. The objective of this work is to develope a reliable estimate on the possible synergistic or antagonistic possibility of binary PM components and to quantify the combined effect. We firstly assessed the interactions among PM components in generating the OP based on DTT consumption rate and AA depletion. We started with the standard solution sequence (from 0.005 to 10 µM), including quinones (PQ, 1,2-NQ, and 1,4-NQ) and metals (Cu, Mn, and Fe). The interactions between metals were antagonistic interactions in DTT consumption. Cu showed antagonistic interaction with PQ, but additive with 1,2-NQ and 1,4-NQ. Mn interacted synergistically with 1,4-NQ in DTT consumption but antagonistically with PQ (where CPQ < 2.5 µM) and 1,4-NQ (where CPQ < 2 µM). Fe showed synergistic with quinones in investigated concentration range (from 0.01 to 5 µM). Finally, applying a moderate approach, on the basis of interaction magnitude (M = 5), resulted in 1-17% higher environmental risks, compared with the classical calculation method using simple addition. This work highlights a new approach to quantify the interaction effects between metals and quinones in PM components, and apportioning the components' contributions for PM OP.


Assuntos
Aerossóis/química , Material Particulado/química , Monitoramento Ambiental , Metais , Oxirredução , Estresse Oxidativo , Quinonas
20.
J Chromatogr A ; 1619: 460941, 2020 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-32044124

RESUMO

Carbohydrates (such as levoglucosan) are a class of important water-soluble organic compounds in atmosphere. In this study, a high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) was applied to characterize carbohydrates in aerosol particles. Since carbohydrate was a kind of compound with low response in mass spectrometry, the conventional HPLC-MS/MS method was not sensitive enough to determine it. When acetate acid was added into mobile phase as buffer, the transition of [M+CH3COO]-→[M-H]- could be selected as the quantification ions. In the range from 1.0 µg L-1 to 20 µg mL-1, the coefficients of regression (r2) were more than 0.990, and relative standard deviations (RSD) for replicated injections were lower than 2%. The limit of detection (LOD) and quantification (LOQ) were lower than 2.5 ng L-1 and 10 ng L-1, respectively. The precision and accuracy were examined by spiked samples at three different concentration levels (10 µg L-1, 100 µg L-1, and 500 µg L-1) in five replicates. Recovery ratios ranged from 85% to 115% with RSD lower than 16%. Matrix effects of different carbohydrates ranged from 62% to 120%. The most sensitive HPLC-MS/MS method was developed and validated to analyze 40 aerosol samples successfully. The carbohydrates including three sugar alcohols (threitol, arabitol and sorbitol), one monosaccharide sugar (inositol), two disaccharides (sucrose, trehalose), one anhydrosugar (levoglucosan) and one 2-methyltetrols (2-Methylbutane-1,2,3,4-tretraol) were successfully quantified.


Assuntos
Aerossóis/química , Carboidratos/análise , Cromatografia Líquida de Alta Pressão , Monitoramento Ambiental/métodos , Espectrometria de Massas em Tandem , Atmosfera/química , Limite de Detecção , Reprodutibilidade dos Testes , Água/química
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