Aerosol influence on cloud macrophysical and microphysical properties over the Tibetan Plateau and its adjacent regions.

This study uses aerosol optical depth (AOD) and cloud properties data to investigate the influence of aerosol on the cloud properties over the Tibetan Plateau and its adjacent regions. The study regions are divided as the western part of the Tibetan Plateau (WTP), the Indo-Gangetic Plain (IGP), and the Sichuan Basin (SCB). All three regions show significant cloud effects under low aerosol loading conditions. In WTP, under low aerosol loading conditions, the effective radius of liquid cloud particles (LREF) decreases with the increase of aerosol loading, while the effective radius of ice cloud particles (IREF) and cloud top height (CTH) increase during the cold season. Increased aerosol loading might inhibit the development of warm rain processes, transporting more cloud droplets above the freezing level and promoting ice cloud development. During the warm season, under low aerosol loading conditions, both the cloud microphysical (LREF and IREF) and macrophysical (cloud top height and cloud fraction) properties increase with the increase of aerosol loading, likely due to higher dust aerosol concentration in this region. In IGP, both LREF and IREF increase with the increase in aerosol loading during the cold season. In SCB, LREF increases with the increase in aerosol loading, while IREF decreases, possibly due to the higher hygroscopic aerosol concentration in the SCB during the cold season. Meteorological conditions also modulate the aerosol-cloud interaction. Under different convective available potential energy (CAPE) and relative humidity (RH) conditions, the influence of aerosol on clouds varies in the three regions. Under low CAPE and RH conditions, the relationship between LREF and aerosol in both the cold and warm seasons is opposite in the WTP: LREF decreases with the increase of aerosol in the cold season, while it increases in the warm season. This discrepancy may be attributed to a difference in the moisture condition between the cold and warm seasons in this region. In general, the influence of aerosols on cloud properties in TP and its adjacent regions is characterized by significant nonlinearity and spatial variability, which is likely related to the differences in aerosol types and meteorological conditions between different regions.

Comparison of nebulisation 0.75% ropivacaine with 2% lignocaine for attenuation of haemodynamic response due to intubation: A prospective randomised study.

INTRODUCTION: Laryngoscopy and intubation are associated with the reflex response of hypertension, tachycardia and other intraoperative complications. Nebulised route drug administration and entropy-guided induction enable optimal intubating conditions. AIMS: To compare pre-induction nebulisation between 0.75% ropivacaine and 2% lignocaine in blunting the nasotracheal intubation response. MATERIALS AND METHODS: A total of 100 patients undergoing elective faciomaxillary surgeries were prospectively randomised to receive pre-induction nebulisation: 5mL of 2% lignocaine (100mg) (Group L) or 5mL of 0.75% ropivacaine (37.5mg) (Group R). Patients were induced and intubated (nasotracheal) with entropy monitoring. Observed parameters included systolic blood pressure, diastolic blood pressure, mean arterial pressure, heart rate, entropy at baseline, induction, intubation, post-intubation one, three and five minutes, propofol induction dose, electrocardiogram changes and peri-intubation cough reflex. RESULTS: Ropivacaine aerosol proved significantly better than lignocaine aerosol on haemodynamics (systolic blood pressure, diastolic blood pressure, mean arterial pressure, heart rate) and cough reflex (p < 0.05). Both groups experienced similar entropy changes and propofol induction dose requirements and no fresh electrocardiogram changes (compared with the baseline). CONCLUSION: Pre-induction nebulised ropivacaine offers superior intubating conditions than lignocaine regarding haemodynamic response and cough reflex for faciomaxillary surgeries.

Satellite NO2 Retrieval Complicated by Aerosol Composition over Global Urban Agglomerations: Seasonal Variations and Long-Term Trends (2001-2018).

Tropospheric nitrogen dioxide (NO2) poses a serious threat to the environmental quality and public health. Satellite NO2 observations have been continuously used to monitor NO2 variations and improve model performances. However, the accuracy of satellite NO2 retrieval depends on the knowledge of aerosol optical properties, in particular for urban agglomerations accompanied by significant changes in aerosol characteristics. In this study, we investigate the impacts of aerosol composition on tropospheric NO2 retrieval for an 18 year global data set from Global Ozone Monitoring Experiment (GOME)-series satellite sensors. With a focus on cloud-free scenes dominated by the presence of aerosols, individual aerosol composition affects the uncertainties of tropospheric NO2 columns through impacts on the aerosol loading amount, relative vertical distribution of aerosol and NO2, aerosol absorption properties, and surface albedo determination. Among aerosol compositions, secondary inorganic aerosol mostly dominates the NO2 uncertainty by up to 43.5% in urban agglomerations, while organic aerosols contribute significantly to the NO2 uncertainty by -8.9 to 37.3% during biomass burning seasons. The possible contrary influences from different aerosol species highlight the importance and complexity of aerosol correction on tropospheric NO2 retrieval and indicate the need for a full picture of aerosol properties. This is of particular importance for interpreting seasonal variations or long-term trends of tropospheric NO2 columns as well as for mitigating ozone and fine particulate matter pollution.

Comparison of the Application of Vibrating Mesh Nebulizer and Jet Nebulizer in Chronic Obstructive Pulmonary Disease: A Systematic Review and Meta-analysis.

Objective: To comparison of the application of Vibrating Mesh Nebulizer and Jet Nebulizer in chronic obstructive pulmonary disease (COPD). Research Methods: This systematic review and meta-analysis was conducted following the Preferred Reporting Items for Systematic Review and Meta-analyses (PRISMA) statements. The primary outcome measures analyzed included: The amount of inhaler in the urine sample at 30 minutes after inhalation therapy (USAL0.5), The total amount of inhaler in urine sample within 24 hours (USAL24), Aerosol emitted, Forced expiratory volume in 1 second (FEV1), Forced vital capacity (FVC). Results: Ten studies were included with a total of 314 study participants, including 157 subjects in the VMN group and 157 subjects in the JN group. The data analysis results of USAL0.5, MD (1.88 [95% CI, 0.95 to 2.81], P = 0.000), showed a statistically significant difference. USAL24, MD (1.61 [95% CI, 1.14 to 2.09], P = 0.000), showed a statistically significant difference. The results of aerosol emitted showed a statistically significant difference in MD (3.44 [95% CI, 2.84 to 4.04], P = 0.000). The results of FEV1 showed MD (0.05 [95% CI, -0.24 to 0.35], P=0.716), the results were not statistically significant. The results of FVC showed MD (0.11 [95% CI, -0.18 to 0.41], P=0.459), the results were not statistically significant. It suggests that VMN is better than JN and provides higher aerosols, but there is no difference in improving lung function between them. Conclusion: VMN is significantly better than JN in terms of drug delivery and utilization in the treatment of patients with COPD. However, in the future use of nebulizers, it is important to select a matching nebulizer based on a combination of factors such as mechanism of action of the nebulizer, disease type and comorbidities, ventilation strategies and modes, drug formulations, as well as cost-effectiveness, in order to achieve the ideal treatment of COPD.

Development of a dry powder insufflation device with application in in vitro cell-based assays in the context of respiratory delivery.

Research on pharmaceutical dry powders has been increasing worldwide, along with increased therapeutic strategies for an application through the pulmonary or the nasal routes. In vitro methodologies and tests that mimic the respiratory environment and the process of inhalation itself are, thus, essential. The literature frequently reports cell-based in vitro assays that involve testing the dry powders in suspension. This experimental setting is not adequate, as both the lung and the nasal cavity are devoid of abundant liquid. However, devices that permit powder insufflation over cells in culture are either scarce or technically complex and expensive, which is not feasible in early stages of research. In this context, this work proposes the development of a device that allows the delivery of dry powders onto cell surfaces, thus simulating inhalation more appropriately. Subsequently, a quartz crystal microbalance (QCM) was used to establish a technique enabling the determination of dry powder deposition profiles. Additionally, the determination of the viability of respiratory cells (A549) after the insufflation of a dry powder using the developed device was performed. In all, a prototype for dry powder insufflation was designed and developed, using 3D printing methods for its production. It allowed the homogenous dispersion of the insufflated powders over a petri dish and a QCM crystal, and a more detailed study on how dry powders disperse over the supports. The device, already protected by a patent, still requires further improvement, especially regarding the method for powder weighing and the efficiency of the insufflation process, which is being addressed. The impact of insufflation of air and of locust bean gum (LBG)-based microparticles revealed absence of cytotoxic effect, as cell viability roughly above 70% was always determined.

[Source and Cause Analysis of High Concentration of Inorganic Aerosol During Two Typical Pollution Processes in Winter over Tianjin].

Inorganic aerosol is the main component of haze days in winter over Tianjin. In this study, two typical high concentrations of secondary inorganic aerosol (SIA) processes, defined as CASE1 and CASE2, were selected during polluted days in January 2020 over Tianjin, and the effects of meteorological factors, regional transport, and chemical processes were comprehensively investigated combined with observations and numerical models (WRF-NAQPMS). The average SIA concentrations in CASE1 and CASE2 were 76.8 µg·m-3 and 66.0 µg·m-3, respectively, and the nitrate concentration was higher than that of sulfate and ammonium, which were typical nitrate-dominated pollution processes. Meteorological conditions played a role in inorganic aerosol formation. The temperature of approximately -6-0℃ and 2-4℃ and the relative humidity of 50%-60% and 80%-100% would be suitable conditions for the high SIA concentration (>80 µg·m-3) in CASE1, whereas the temperature of approximately 2-4℃ and the relative humidity of 60%-70% would be suitable in CASE2. The average contribution rates of external sources to SIA in the CASE1 and CASE2 processes were 62.3% and 22.1%, which were regional transport-dominant processes and local emission-dominant processes, respectively. The contribution of the local emission of CASE1 to nitrate and sulfate was 16.2 µg·m-3 and 8.2 µg·m-3, respectively, higher than that of external sources (31.7 µg·m-3 and 8.8 µg·m-3). the local contribution of CASE2 to nitrate and sulfate was 29.3 µg·m-3 and 25.1 µg·m-3, respectively, whereas the contribution from external sources was 8.1 µg·m-3 and 9.4 µg·m-3, respectively. The quantitative result indicated that local formation and regional transport resulted in higher nitrate concentration than sulfate in CASE1, in contrast to only local sources in CASE2. The gas phase reaction was the main source of inorganic aerosol formation, contributing 48.9% and 57.8% in CASE1 and CASE2, respectively, whereas the heterogeneous reactions were also important processes, with contribution rates of 48.1% and 42.2% to SIA. The effect of aqueous phase reaction was negligible.

Aerosol-Synthesized Surfactant-Free Single-Walled Carbon Nanotube-Based NO2 Sensors: Unprecedentedly High Sensitivity and Fast Recovery.

This study pioneers a chemical sensor based on surfactant-free aerosol-synthesized single-walled carbon nanotube (SWCNT) films for detecting nitrogen dioxide (NO2). Unlike conventional CNTs, the SWCNTs used in this study exhibit one of the highest surface-to-volume ratios. They show minimal bundling without the need for surfactants and have the lowest number of defects among reported CNTs. Furthermore, the dry-transferrable and facile one-step lamination results in promising industrial viability. When applied to devices, the sensor shows excellent sensitivity (41.6% at 500 ppb), rapid response/recovery time (14.2/120.8 s), a remarkably low limit of detection (below ≈0.161 ppb), minimal noise, repeatability for more than 50 cycles without fluctuation, and long-term stability for longer than 6 months. This is the best performance reported for a pure CNT-based sensor. In addition, the aerosol SWCNTs demonstrate consistent gas-sensing performance even after 5000 bending cycles, indicating their suitability for wearable applications. Based on experimental and theoretical analyses, the proposed aerosol CNTs are expected to overcome the limitations associated with conventional CNT-based sensors, thereby offering a promising avenue for various sensor applications.

In vitro toxicological evaluation of glo menthol and non-menthol heated tobacco products.

Heated tobacco products (HTPs) are non-combustible, inhaled tobacco products that generate an aerosol with fewer and lower levels of toxicants, with a potential to reduce risk relative to cigarette smoking. Here, we assessed in vitro toxicological effects of three menthol (glo neo neoCLICK, neo Smooth Menthol and Fresh Menthol) and one non-menthol (neo Smooth Tobacco) variants of glo HTP, along with market comparators for cigarettes and HTPs. Limited chemical characterization of the study products revealed significantly lower levels of acetaldehyde, acrolein, crotanaldehyde and formaldehyde in test samples from HTPs than those from cigarettes. The glo HTPs were non-mutagenic in the bacterial reverse mutagenesis assay. Although, the whole aerosol exposures of glo HTPs were classified as genotoxic in the in vitro micronucleus assay, and cytotoxic in the NRU (monolayer) and MTT (3 dimensional EpiAirway™ tissues) assays, the cigarette comparators were the most toxic study products in each of these assessments. Further, glo HTPs elicited oxidative stress responses only at the highest dose tested, whereas the cigarette comparators were potent inducers of oxidative stress at substantially lower doses in the EpiAirway tissues. The comparator (non-glo) HTP results were similar to the glo HTPs in these assays. Thus, the glo HTPs exhibit substantially lower toxicity compared to cigarettes.

Triage-initiated intranasal fentanyl for hip fractures in an Emergency Department - Results from introduction of an analgesic guideline.

BACKGROUND: Pain relief is a priority for patients with hip fractures who present to Emergency Departments (EDs). Intranasal fentanyl (INF) is an ideal option for nurse initiated analgesia as it does not require intravenous access and can expedite care prior to examination by a physician. LOCAL PROBLEM: Pain relief in patients with hip fractures is delayed during episodes of ED crowding. METHODS: A retrospective medical record review was conducted following introduction of an INF guideline in an adult ED in 2018. Patients were included over a 4-month period during which the guideline was introduced. Historical and concurrent control groups receiving usual care were compared to patients receiving INF. INTERVENTIONS: This quality improvement initiative investigated whether an INF analgesia at triage guideline would decrease time to analgesic administration in adults with hip fracture in ED. RESULTS: This study included 112 patients diagnosed with fractured hips of which 16 patients received INF. Background characteristics were similar between groups. Mean time to analgesic administration (53 v 110 minutes), time to x-ray (46 v 75 minutes), and ED length of stay (234 v 298 minutes) were significantly decreased in the intervention group. Inadequate documentation was a limiting factor in determining improved efficacy of analgesia. CONCLUSION: Use of triage-initiated INF significantly decreased time to analgesic administration, time to imaging and overall length of stay in ED.

Inflammatory-Targeted Lipid Carrier as a New Nanomaterial to Formulate an Inhaled Drug Delivery System.

There is a pressing need for efficacious therapies in the field of respiratory diseases and infections. Lipid nanocarriers, administered through aerosols, represent a promising tool for maximizing therapeutic concentration in targeted cells and minimizing systemic exposure. However, this approach requires the application of efficient and safe nanomaterials. Palmitoylethanolamide (PEA), an endocannabinoid-like endogenous lipid, plays a crucial role in providing protective mechanisms during inflammation, making it an interesting material for preparing inhalable lipid nanoparticles (LNPs). This report aims to preliminarily explore the in vitro behavior of LNPs prepared with PEA (PEA-LNPs), a new inhalable inflammatory-targeted nanoparticulate drug carrier. PEA-LNPs exhibited a size of about 250 nm, a rounded shape, and an marked improvement in PEA solubility in comparison to naked PEA, indicative of easily disassembled nanoparticles. A twin glass impinger instrument was used to screen the aerosol performance of PEA-LNP powders, obtained via freeze-drying in the presence of two quantities of mannose as a cryoprotectant. Results indicated that a higher amount of mannose improved the emitted dose (ED), and in particular, the fine particle fraction (FPF). A cytotoxicity assay was performed and indicated that PEA-LNPs are not toxic towards the MH-S alveolar macrophage cell line up to concentrations of 0.64 mg/mL, and using coumarin-6 labelled particles, a rapid internalization into the macrophage was confirmed. This study demonstrates that PEA could represent a suitable material for preparing inhalable lipid nanocarrier-based dry powders, which signify a promising tool for the transport of drugs employed to treat respiratory diseases and infections.

Hydrolysis reactivity reveals significant seasonal variation in the composition of organic peroxides in ambient PM2.5.

Atmospheric organic peroxides (POs) play a key role in the formation of O3 and secondary organic aerosol (SOA), impacting both air quality and human health. However, there still remain technical challenges in investigating the reactivity of POs in ambient aerosols due to the instability and lack of standards for POs, impeding accurate evaluation of their environmental impacts. In the present study, we conducted the first attempt to categorize and quantify POs in ambient PM2.5 through hydrolysis, which is an important transformation pathway for POs, thus revealing the reactivities of various POs. POs were generally categorized into hydrolyzable POs (HPO) and unhydrolyzable POs (UPO). HPO were further categorized into three groups: short-lifetime HPO (S-HPO), intermediate-lifetime HPO (I-HPO), and long-lifetime HPO (L-HPO). S-HPO and L-HPO are typically formed from Criegee intermediate (CI) and RO2 radical reactions, respectively. Results show that L-HPO are the most abundant HPO, indicating the dominant role of RO2 pathway in HPO formation. Despite their lower concentration compared to L-HPO, S-HPO make a major contribution to the HPO hydrolysis rate due to their faster rate constants. The hydrolysis of PM2.5 POs accounts for 19 % of the nighttime gas-phase H2O2 growth during the summer observation, constituting a noteworthy source of gas-phase H2O2 and contributing to the atmospheric oxidation capacity. Seasonal and weather conditions significantly impact the composition of POs, with HPO concentrations in summer being significantly higher than those in winter and elevated under rainy and nighttime conditions. POs are mainly composed of HPO in summer, while in winter, POs are dominated by UPO.

Dust and climate interactions in the Middle East: Spatio-temporal analysis of aerosol optical depth and climatic variables.

The Middle East (ME) is grappling with an alarming increase in dust levels, measured as aerosol optical depth (AOD), which poses significant threats to air quality, human health, and ecological stability. This study aimed to investigate correlations between climate and non-climate driving factors and AOD in the ME over the last four-decade (1980-2020), based on analysis of three variables: actual evapotranspiration (AET), potential evapotranspiration (PET), and precipitation (P). A comprehensive analysis is conducted to discern patterns and trends, with a particular focus on regions such as Rub al-Khali, Ad-Dahna, An-Nafud Desert, and southern Iraq, where consistently high dust levels were observed. 77 % of the study area is classified as arid or semi-arid based on the aridity index. Our results indicate an upward trend in dust levels in Iraq, Iran, Yemen, and Saudi Arabia. We noted an increasing AET trend in regions such as the Euphrates and Tigris basin, northern-Iran, and the Nile region, along with rising PET levels in arid and semi-arid zones such as Iran, Iraq, and Syria. Conversely, P showed a notable decrease in northern-Iraq, Syria, southwestern Iran, and southern-Turkey. Comparison of long-term changes (10-year moving averages) of AOD and P showed a consistent increase in AOD with P levels decreasing in all climate regions. The Budyko space analysis indicates shifts in evaporation ratio across different climate classes from 1980 to 2020, with predominant movement patterns towards higher aridity indices in arid and semi-arid regions, while factors beyond long-term aridity changes influence shifts in evaporation ratio across various climatic zones. The Middle East experiences complex and intricate interactions between dust events and their drivers. To address this issue, a comprehensive and multi-system approach is necessary, which considers both climate and non-climate drivers. Moreover, an efficient dust control strategy should include soil and water conservation, advanced monitoring, and public awareness campaigns that involve regional and international collaboration.

Analysis of characteristics and changes in three-dimensional spatial and temporal distribution of aerosol types in Central Asia.

Atmospheric aerosol types and characteristics have regional and seasonal characteristics mainly due spatial and temporal differences in emission sources and diffuse transport conditions. We explored regional three-dimensional spatial and temporal distribution characteristics of aerosol types in Central Asia from daytime to nighttime by using long-term (2007-2021) CALIPSO lidar measurements. The three results are as follows: (1) Average aerosol optical depth (AOD) values during the 14 years were 0.44 and 0.47 during daytime and nighttime, respectively, with an overall decreasing trend, among which the AOD in spring in the southern border region and in winter in the northern border region showed high values, 0.66 and 0.31 during daytime and 0.69 and 0.33 during nighttime, respectively, and nighttime AOD values were higher than those of daytime, possibly due to the lower signal-to-noise ratio of the CALIPSO during the daytime than during the nighttime. (2) The primary representative aerosol type in the Taklamakan Desert region being pure sand and dust, and more apparent winter-polluted sand and dust exist along the northern slope of the Tianshan Mountains in Xinjiang in winter than in other areas. High-altitude soot mainly existed below 4 km and was primarily concentrated in northern Central Asia, with the highest values (0.016 and 0.003) in summer and winter, respectively, which may be due to different diffusion and transport conditions. (3) Dust aerosols in spring were mainly concentrated in the region of 2-6 km in the Taklamakan Desert area; pure dust particles in summer and fall lifted height diffusion and gradually moved to the northern border region; polluted dust was mainly in northern Xinjiang in fall and winter and spread to northern Central Asia; and the average top height of aerosols in the transmission process reached the top of the troposphere, and transmission height was higher than source area.

Response of biogenic secondary organic aerosol formation to anthropogenic NOx emission mitigation.

This study investigates the effects of anthropogenic nitrogen oxide (NOx) mitigation reduction on secondary organic aerosol (SOA) formation from monoterpene and sesquiterpene precursors across Europe, using the three-dimensional (3-D) Chemical Transport Model (CTM) CHIMERE. Two SOA mechanisms of varying complexity are employed: the GENOA-generated Biogenic Mechanism (GBM) and the Hydrophobic/Hydrophilic Organic mechanism (H2O). GBM is a condensed SOA mechanism generated by automatic reduction from near-explicit chemical mechanisms (i.e., the Master Chemical Mechanism - MCM and the peroxy radical autoxidation mechanism - PRAM) using the GENerator of Reduced Organic Aerosol Mechanisms version 2.0 (GENOA v2.0). Conversely, the H2O mechanism is developed primarily based on experimental data, with simplified chemical pathways and SOA formation yields reflecting those from chamber experiments. In the 3-D simulations conducted for the summer of 2018 over Europe, the implementation of GBM significantly improved the model's performance in comparison to simulations using the H2O mechanism, yielding results more consistent with measured aerosol concentrations extracted from the EBAS database. In response to NOx emission mitigation, simulated SOA concentrations increase with GBM but decrease when using the H2O mechanism, unless a highly oxygenated molecules (HOMs) formation scheme is incorporated. The SOA composition becomes more oxidized and concentrations elevate after NOx reduction, particularly in simulations using GBM. These higher concentrations are likely due to enhanced reaction rates of organic peroxy radicals (RO2) with HO2, resulting in more oxidized products from monoterpene degradation that favors HOM formation. The results suggest that detailed SOA mechanisms including autoxidation are necessary for accurate predictions of SOA concentrations in 3-D modeling.

Social Network Analysis of e-Cigarette-Related Social Media Influencers on Twitter/X: Observational Study.

BACKGROUND: An e-cigarette uses a battery to heat a liquid that generates an aerosol for consumers to inhale. e-Cigarette use (vaping) has been associated with respiratory disease, cardiovascular disease, and cognitive functions. Recently, vaping has become increasingly popular, especially among youth and young adults. OBJECTIVE: The aim of this study was to understand the social networks of Twitter (now rebranded as X) influencers related to e-cigarettes through social network analysis. METHODS: Through the Twitter streaming application programming interface, we identified 3,617,766 unique Twitter accounts posting e-cigarette-related tweets from May 3, 2021, to June 10, 2022. Among these, we identified 33 e-cigarette influencers. The followers of these influencers were grouped according to whether or not they post about e-cigarettes themselves; specifically, the former group was defined as having posted at least five e-cigarette-related tweets in the past year, whereas the latter group was defined as followers that had not posted any e-cigarette-related tweets in the past 3 years. We randomly sampled 100 user accounts among each group of e-cigarette influencer followers and created corresponding social networks for each e-cigarette influencer. We compared various network measures (eg, clustering coefficient) between the networks of the two follower groups. RESULTS: Major topics from e-cigarette-related tweets posted by the 33 e-cigarette influencers included advocating against vaping policy (48.0%), vaping as a method to quit smoking (28.0%), and vaping product promotion (24.0%). The follower networks of these 33 influencers showed more connections for those who also post about e-cigarettes than for followers who do not post about e-cigarettes, with significantly higher clustering coefficients for the former group (0.398 vs 0.098; P=.005). Further, networks of followers who post about e-cigarettes exhibited substantially more incoming and outgoing connections than those of followers who do not post about e-cigarettes, with significantly higher in-degree (0.273 vs 0.084; P=.02), closeness (0.452 vs 0.137; P=.04), betweenness (0.036 vs 0.008; P=.001), and out-of-degree (0.097 vs 0.014; P=.02) centrality values. The followers who post about e-cigarettes also had a significantly (P<.001) higher number of followers (n=322) than that of followers who do not post about e-cigarettes (n=201). The number of tweets in the networks of followers who post about e-cigarettes was significantly higher than that in the networks of followers who do not post about e-cigarettes (93 vs 43; P<.001). Two major topics discussed in the networks of followers who post about e-cigarettes included promoting e-cigarette products or vaping activity (55.7%) and vaping being a help for smoking cessation and harm reduction (44.3%). CONCLUSIONS: Followers of e-cigarette influencers who also post about e-cigarettes have more closely connected networks than those of followers who do not themselves post about e-cigarettes. These findings provide a potentially practical intervention approach for future antivaping campaigns.

Enhanced Light Absorption and Elevated Viscosity of Atmospheric Brown Carbon through Evaporation of Volatile Components.

Samples of brown carbon (BrC) material were collected from smoke emissions originating from wood pyrolysis experiments, serving as a proxy for BrC representative of biomass burning emissions. The acquired samples, referred to as "pyrolysis oil (PO1)," underwent subsequent processing by thermal evaporation of their volatile compounds, resulting in a set of three additional samples with volume reduction factors of 1.33, 2, and 3, denoted as PO1.33, PO2, and PO3. The chemical compositions of these POx samples and their BrC chromophore features were analyzed using a high-performance liquid chromatography instrument coupled with a photodiode array detector and a high-resolution mass spectrometer. The investigation revealed a noteworthy twofold enhancement of BrC light absorption observed for the progression of PO1 to PO3 samples, assessed across the spectral range of 300-500 nm. Concurrently, a decrease in the absorption Ångstrom exponent (AAE) from 11 to 7 was observed, indicating a weaker spectral dependence. The relative enhancement of BrC absorption at longer wavelengths was more significant, as exemplified by the increased mass absorption coefficient (MAC) measured at 405 nm from 0.1 to 0.5 m2/g. Molecular characterization further supports this darkening trend, manifesting as a depletion of small oxygenated, less absorbing monoaromatic compounds and the retention of relatively large, less polar, more absorbing constituents. Noteworthy alterations of the PO1 to PO3 mixtures included a reduction in the saturation vapor pressure of their components and an increase in viscosity. These changes were quantified by the mean values shifting from approximately 1.8 × 103 µg/m3 to 2.3 µg/m3 and from ∼103 Pa·s to ∼106 Pa·s, respectively. These results provide quantitative insights into the extent of BrC aerosol darkening during atmospheric aging through nonreactive evaporation. This new understanding will inform the refinement of atmospheric and chemical transport models.

Optical properties and radiative forcing of carbonaceous aerosols in a valley city under persistent high temperature.

Carbonaceous aerosols were collected in the valley city of Baoji city in Northern China in August 2022. The light absorption characteristics and influencing factors of black carbon (BC) and brown carbon (BrC) were analyzed, and their radiative forcing was estimated. The results showed that the light absorption of secondary brown carbon [AbsBrC,sec (370)] was 7.5 ± 2.4 Mm-1, which was 2.5 times that of primary brown carbon [AbsBrC,pri (370), 3.0 ± 1.2 Mm-1]. During the study period, the absorption Ångström exponent (AAE) of aerosol was 1.6, indicating that there was obvious secondary aerosol formation or carbonaceous aerosol aging in the valley city of Baoji. Except for secondary BrC (BrCsec), the light absorption coefficient (Abs) and mass absorption efficiency (MAE) of BC and primary BrC (BrCpri) during the persistent high temperature period (PHT) were higher than those during the normal temperature period (NT) and the precipitation period (PP), which indicated that the light absorption capacity of black carbon and primary brown carbon increased, while the light absorption capacity of secondary brown carbon decreased under persistent high temperature period. Secondary aerosols sulfide (SO42-), nitrate (NO3-) and secondary organic carbon (SOC) are important factors for promoting the light absorption enhancemen of BC and BrCpri and photobleaching of BrCsec during persistent high temperature period. The Principal Component Analysis-Multiple Linear Regression (PCA-MLR) model showed that traffic emissions was the most important source of pollution in Baoji City. Based on this, the secondary source accelerates the aging of BC and BrC, causing changes in light absorption. During PHT, the radiative forcing of BC and BrCpri were enhanced, while the radiative forcing of BrCsec was weakened, but the positive radiative forcing generated by them may aggravate the high-temperature disaster.

Major source categories of PM2.5 oxidative potential in wintertime Beijing and surroundings based on online dithiothreitol-based field measurements.

Fine particulate matter (PM2.5) causes millions of premature deaths each year worldwide. Oxidative potential (OP) has been proposed as a better metric for aerosol health effects than PM2.5 mass concentration alone. In this study, we report for the first time online measurements of PM2.5 OP in wintertime Beijing and surroundings based on a dithiothreitol (DTT) assay. These measurements were combined with co-located PM chemical composition measurements to identify the main source categories of aerosol OP. In addition, we highlight the influence of two distinct pollution events on aerosol OP (spring festival celebrations including fireworks and a severe regional dust storm). Source apportionment coupled with multilinear regression revealed that primary PM and oxygenated organic aerosol (OOA) were both important sources of OP, accounting for 41 ± 12 % and 39 ± 10 % of the OPvDTT (OP normalized by the sampled air volume), respectively. The small remainder was attributed to fireworks and dust, mainly resulting from the two distinct pollution events. During the 3.5-day spring festival period, OPvDTT spiked to 4.9 nmol min-1 m-3 with slightly more contribution from OOA (42 ± 11 %) and less from primary PM (31 ± 15 %). During the dust storm, hourly-averaged PM2.5 peaked at a very high value of 548 µg m-3 due to the dominant presence of dust-laden particles (88 % of total PM2.5). In contrast, only mildly elevated OPvDTT values (up to 1.5 nmol min-1 m-3) were observed during this dust event. This observation indicates that variations in OPvDTT cannot be fully explained using PM2.5 alone; one must also consider the chemical composition of PM2.5 when studying aerosol health effects. Our study highlights the need for continued pollution control strategies to reduce primary PM emissions, and more in-depth investigations into the source origins of OOA, to minimize the health risks associated with PM exposure in Beijing.

Investigation of the in vitro toxic effects induced by real-time aerosol of electronic cigarette solvents using microfluidic chips.

The safety of propylene glycol (PG) and vegetable glycerin (VG) as solvents in electronic cigarette liquid has received increasing attention and discussion. However, the conclusions derived from toxicity assessments conducted through animal experiments and traditional in vitro methodologies have consistently been contentious. This study constructed an original real-time aerosol exposure system, centered around a self-designed microfluidic bionic-lung chip, to assess the biological effects following exposure to aerosols from different solvents (PG, PG/VG mixture alone and PG/VG mixture in combination with nicotine) on BEAS-2B cells. The study aimed to investigate the impact of aerosols from different solvents on gene expression profiles, intracellular biomarkers (i.e., reactive oxygen species content, nitric oxide content, and caspase-3/7 activity), and extracellular biomarkers (i.e., IL-6, IL-8, TNF-α, and malondialdehyde) of BEAS-2B cells on-chip. Transcriptome analyses suggest that ribosomal function could serve as a potential target for the impact of aerosols derived from various solvents on the biological responses of BEAS-2B cells on-chip. And the results showed that aerosols of PG/VG mixtures had significantly less effect on intracellular and extracellular biomarkers in BEAS-2B cells than aerosols of PG, whereas increasing nicotine levels would significantly elevate these effects of aerosol from PG/VG mixture.