Accessing the Low-Polar Molecular Composition of Boreal and Arctic Peat-Burning Organic Aerosol via Thermal Analysis and Ultrahigh-Resolution Mass Spectrometry: Structural Motifs and Their Formation.

Peatland fires emit organic carbon-rich particulate matter into the atmosphere. Boreal and Arctic peatlands are becoming more vulnerable to wildfires, resulting in a need for better understanding of the emissions of these special fires. Extractable, nonpolar, and low-polar organic aerosol species emitted from laboratory-based boreal and Arctic peat-burning experiments are analyzed by direct-infusion atmospheric pressure photoionization (APPI) ultrahigh-resolution mass spectrometry (UHRMS) and compared to time-resolved APPI UHRMS evolved gas analysis from the thermal analysis of peat under inert nitrogen (pyrolysis) and oxidative atmosphere. The chemical composition is characterized on a molecular level, revealing abundant aromatic compounds that partially contain oxygen, nitrogen, or sulfur and are formed at characteristic temperatures. Two main structural motifs are identified, single core and multicore, and their temperature-dependent formation is assigned to the thermal degradation of the lignocellulose building blocks and other parts of peat.

Laboratory study on the characteristics of fresh and aged PM1 emitted from typical forest vegetation combustion in Southwest China.

The frequency and intensity of forest fires are amplified by climate change. Substantial quantities of PM1 emitted from forest fires can undergo gradual atmospheric dispersion and long-range transport, thus impacting air quality far from the source. However, the chemical composition and physical properties of PM emitted from forest fires and its changes during atmospheric transport remain uncertain. In this study, the evolution of organic carbon (OC), elemental carbon (EC), water-soluble ions, and water-soluble metals in the particulate phase of smoke emitted from the typical forest vegetation combustion in Southwest China before and after photo-oxidation was investigated in the laboratory. Two aging periods of 5 and 9 days were selected. The OC and TC mass concentrations tended to decrease after 9-days aged compared to fresh emissions. OP, OC2, and OC3 in PM1 are expected to be potential indicators of fresh smoke, while OC3 and OC4 may serve as suitable markers for identifying aged carbon sources from the typical forest vegetation combustion in Southwest China. K+ exhibited the highest abundant water-soluble ion in fresh PM1, whereas NO3- became the most abundant water-soluble ion in aged PM1. NH4NO3 emerged as the primary secondary inorganic aerosol emitted from typical forest vegetation combustion in Southwest China. Notably, a 5-day aging period proved insufficient for the complete formation of the secondary inorganic aerosols NH4NO3 and (NH4)2SO4. After aging, the mass concentration of the water-soluble metal Ni in PM1 from typical forest vegetation combustion in Southwest China decreased, while the mean mass concentrations of all other water-soluble metals increased in varying degrees. These findings provide valuable data support and theoretical guidance for studying the atmospheric evolution of forest fire aerosols, as well as contribute to policy formulation and management of atmospheric environment safety and human health.

Measurement of inward leakage of full-face masks in EN and ISO standards: comparison of gas and aerosol test agents.

In Europe, respiratory protective devices must be certified before they can be marketed. Among the parameters of interest, inward leakage (IL) characterizes the tightness between the face seal and the face, to verify that the device is well-designed. European standard EN 13274-1 (2001) and International Organization for Standardization (ISO) standard ISO 16900-1 (2019) specify that IL should be measured using sodium chloride (NaCl) aerosol or sulfur hexafluoride (SF6) gas. For reusable masks made of nonporous materials, both test agents are considered equally acceptable. However, the few studies that have compared IL values measured with various aerosols and gases have come to divergent conclusions. This work then aimed to measure IL with the test agents recommended by the standards to determine whether they are really equivalent. Since krypton (Kr) is an interesting candidate for replacing SF6 in standard tests, IL was assessed with SF6 and Kr simultaneously, and with NaCl aerosol using various calculation methods. Tests were carried out on 5 models of full-face masks donned on a headform connected to a breathing machine simulating 3 sinusoidal breathing rates of various intensities. The respirator fit on the headform was evaluated using a controlled negative pressure method to determine a manikin fit factor. Four scenarios were then tested to represent very poor, bad, good, and excellent fit. Gas concentration was measured using a mass spectrometer, and IL was calculated for SF6 and Kr. A combination of 3 devices allowed the determination of the number-based concentration of particles with diameters between 20 nm and 2 µm, and IL was calculated for each of the 33 channels, as well as using a cumulative number concentration. In addition, to comply with standards, a conversion was carried out to calculate IL using a cumulative mass concentration. The results of this work evidenced that the IL values measured with NaCl were systematically lower than those determined with gases. IL was also shown to vary with particle size, with a maximum value exceeding that calculated with cumulative concentrations (in number or mass). As part of the revision of the standards, protocols for measuring inward leakage should be redefined. On the one hand, acceptability thresholds should be re-evaluated according to the nature of the test agent (gas or aerosol), as it is clear that the 2 options do not give the same results for a given configuration. On the other hand, the aerosol leakage measurement protocol needs to be reworked to enable the measurement of a well-defined, robust, and reproducible inward leakage value.

An improved meteorological variables-based aerosol optical depth estimation method by combining a physical mechanism model with a two-stage model.

A two-stage model integrating a spatiotemporal linear mixed effect (STLME) and a geographic weight regression (GWR) model is proposed to improve the meteorological variables-based aerosol optical depth (AOD) retrieval method (Elterman retrieval model-ERM). The proposed model is referred to as the STG-ERM model. The STG-ERM model is applied over the Beijing-Tianjin-Hebei (BTH) region in China for the years 2019 and 2020. The results show that data coverage increased by 39.0% in 2019 and 40.5% in 2020. Cross-validation of the retrieval results versus multi-angle implementation of atmospheric correction (MAIAC) AOD shows the substantial improvement of the STG-ERM model over earlier meteorological models for AOD estimation, with a determination coefficient (R2) of daily AOD of 0.86, root mean squared prediction error (RMSE) and the relative prediction error (RPE) of 0.10 and 36.14% in 2019 and R2 of 0.86, RMSE of 0.12 and RPE of 37.86% in 2020. The fused annual mean AOD indicates strong spatial variation with high value in south plain and low value in northwestern mountainous areas of the BTH region. The overall spatial seasonal mean AOD ranges from 0.441 to 0.586, demonstrating strongly seasonal variation. The coverage of STG-ERM retrieved AOD, as determined in this exercise by leaving out part of the meteorological data, affects the accuracy of fused AOD. The coverage of the meteorological data has smaller impact on the fused AOD in the districts with low annual mean AOD of less than 0.35 than that in the districts with high annual mean AOD of greater than 0.6. If available, continuous daily meteorological data with high spatiotemporal resolution can improve the model performance and the accuracy of fused AOD. The STG-ERM model may serve as a valuable approach to provide data to fill gaps in satellite-retrieved AOD products.

[Change Characteristics of Carbonaceous Aerosol in Chengdu from 2018 to 2021].

Carbonaceous aerosol is an important component of atmospheric fine particulates （PM2.5） that has an important effect on global climate change, atmospheric visibility, regional air quality, and human health. In order to investigate the long-term change characteristics of carbonaceous aerosols under the background of emission reduction, the concentrations of organic carbon （OC）, elemental carbon （EC） in PM2.5 samples, and volatile organic compounds （VOCs） in Chengdu from 2018 to 2021 and the corresponding meteorological factors were obtained through real-time online monitoring. The results showed that the average ρ（OC） and ρ（EC） during the monitoring period were （10.9 ±5.7） µg·m-3 and （2.6 ±1.9） µg·m-3, accounting for 25.2% and 6.0% of PM2.5, respectively, and the average ρ（SOC） was （5.7 ±3.3） µg·m-3, accounting for 52.9% of OC. The concentrations of OC, EC, and PM2.5 showed a downward trend from 2018 to 2020 [PM2.5： The concentration of average annual decrease was -7.1 µg·ï¼ˆm3·a） -1, with an average annual decrease of -14.6 %·a-1； OC： -1.7 µg·ï¼ˆm3·a）-1, -14.2 %·a-1； EC： -0.1 µg·ï¼ˆm3·a）-1, -4.4 %·a-1], and the concentrations of each pollutant in 2021 rebounded in different ranges compared with those in 2020. The concentrations of PM2.5 and OC were as follows： winter > spring > autumn > summer, and the concentrations of EC were as follows： winter > autumn > spring > summer. The proportions of OC and EC were higher in summer and autumn than in other seasons, with the average proportions of 26.8% and 6.9%, respectively. With the aggravation of the pollution level, OC, EC, and SOC concentrations gradually increased, but the proportions in PM2.5 showed a gradual downtrend, indicating that the control factor of PM2.5 pollution in Chengdu was not the carbon component. Source apportionment results showed that carbonaceous aerosols in Chengdu were mainly affected by motor vehicles, industrial sources, biomass combustion sources, and VOCs secondary reaction. From 2019 to 2021, EC was affected by the characteristic components of motor vehicles and decreased yearly. OC and EC were affected by VOCs more in spring and autumn than in other seasons. VOCs emission management should be increased in spring and autumn to reduce the impact of secondary reaction.

Outcome of patients with peritoneal metastasis from ovarian cancer treated with Pressurized IntraPeritoneal Aerosol Chemotherapy (PIPAC).

Objectives: There are few data on Pressurized IntraPeritoneal Aerosol Chemotherapy with cisplatin and doxorubicin (PIPAC C/D) in women with primary unresectable or recurrent platinum-resistant peritoneal metastasis (PM) from ovarian cancer (OC). We evaluated survival, histological and cytological response, Quality of Life (QoL) and toxicity after PIPAC C/D in these patients. Methods: Retrospective analysis of patients from the prospective PIPAC-OPC1 and -OPC2 studies. The histological response was evaluated by the Peritoneal Regression Grading Score (PRGS). QoL questionnaires were collected at baseline and after third PIPAC or 60 days. Adverse events were collected until 30 days after the last PIPAC. Demographic and survival data were analysed based on intention to treat. Response, QoL and toxicity were analysed per protocol (≥1 PIPAC). Results: Twenty-nine patients were included. Five patients (17 %) were non-accessible at PIPAC 1. One patient was excluded due to liver metastases at PIPAC 1. Thus, 23 patients had 76 PIPACs (median 2, range 1-12). Median overall survival was 8.2 months (95 % CI 4.4-10.3) from PIPAC 1. Biopsy data were available for 22 patients, and seven (32 %) patients had a major/complete histological response (PRGS≤2) at PIPAC 3. No cytological conversions were registered. Symptoms and function scores worsened, while emotional scores improved. Three patients had severe adverse reactions (two ileus, one pulmonary embolism); no life-threatening reactions or treatment-related mortality was observed. Conclusions: PIPAC C/D was feasible and induced histological regression in a substantial proportion of patients with platinum-resistant PM from OC. Larger studies are needed to evaluate impact on survival.

RNA expression profiling of peritoneal metastasis from pancreatic cancer treated with Pressurized Intraperitoneal Aerosol Chemotherapy (PIPAC).

Objectives: Pressurized Intraperitoneal Aerosol Chemotherapy (PIPAC) is an experimental treatment option in peritoneal metastasis from pancreatic cancer (PM-PC). Aims were to examine mRNA profile of fibrosis due to response after systemic chemotherapy and PIPAC (Regression) compared to treatment-naïve PM-PC and chronic cholecystitis-related peritoneal fibrosis (Controls). Methods: Peritoneal biopsies (PBs) from PM-PC patients who had undergone systemic chemotherapy and PIPAC were evaluated with Peritoneal Regression Grading Score (PRGS). We extracted RNA from PBs with Regression (PRGS 1, n=11), treatment-naïve PM-PC (n=10), and Controls (n=10). Profiling of 800 mRNAs was performed (NanoString nCounter, PanCancer Immuno-Oncology 360 (IO-360) and 30 additional stroma-related mRNAs). Results: Regression vs. PM-PC identified six up-regulated and 197 down-regulated mRNAs (FDR≤0.05), linked to TNF-α signaling via NF-kB, G2M checkpoint, epithelial-mesenchymal transition, estrogen response, and coagulation. Regression vs. Controls identified 43 significantly up-regulated mRNAs, linked to interferon-α response, and down-regulation of 99 mRNAs, linked to TNF-α signaling via NF-kB, inflammatory response, epithelial-mesenchymal transition, KRAS signaling, and hypoxia (FDR≤0.05). Conclusions: In regressive fibrosis of PM-PC after systemic chemotherapy and PIPAC (Regression), downregulation of mRNAs related to key tumor biological pathways was identified. Regression also showed transcriptional differences from unspecific, benign fibrosis (Controls). Future studies should explore whether mRNA profiling of PBs with PM from PC or other primaries holds prognostic or predictive value.

Review on treatment of pleural metastasis and malignant pleural effusion with Pressurized IntraThoracic Aerosol Chemotherapy (PITAC).

Background: Malignant pleural effusion (MPE) is a common and debilitating condition seen in advanced cancer disease, and life-expectancy is short. Symptoms include pain and severe shortness of breath. Current first-line treatment options include pleural drainage using catheters as well as pleurodesis. However, these treatment modalities are often inefficient and patients need repeated procedures. Pressurized IntraThoracic Aerosol Chemotherapy (PITAC) is a minimally invasive procedure, where antineoplastic agents are nebulized under pressure into the pleural space. Content: We present the preliminary safety, feasibility, and response assessment data for PITAC based on a comprehensive literature review. Summary: Five retrospective studies reported data on 38 PITACs in 21 patients. Data were heterogeneous and incomplete on several important aspects such as procedure, safety, local effect and long-term outcomes. PITAC seems technically feasible with a low risk of complications and may provide some reduction in MPE in selected cases. Outlook: PITAC seems feasible, but prospective phase I and II studies are needed to define safety, indications, and efficacy.

Large-eddy simulation of aerosol concentrations in a realistic urban environment: Model validation and transport mechanism.

Air pollution in urban environments exhibits large spatial and temporal variations due to high heterogeneous air flow and emissions. To address the complexity of local air pollutant dynamics, a comprehensive large-eddy simulation using the PALM model system v6.0 was conducted. The distribution of flow and vehicle emitted aerosol particles in a realistic urban environment in Malmö, Sweden, was studied and evaluated against on-site measurements made using portable instrumentation on a spring morning in 2021. The canyon transport mechanisms were investigated, and the convective and turbulent mass-transport rates compared to clarify their role in aerosol transport. The horizontal distribution of aerosols showed acceptable evaluation metrics for both mass and number. Flow and pollutant concentrations were more complex than those in idealized street canyon networks. Vertical turbulent mass-transport rate was found to dominate the mass transport process compared with the convective transport rate, contributing more than 70% of the pollutant transport process. Our findings highlight the necessity of examining various aerosol metric due their distinct dispersion behaviour. This study introduces a comprehensive high-resolution modelling framework that accounts for dynamic meteorological and aerosol background boundary conditions, real-time traffic emission, and detailed building features, offering a robust toll for local urban air quality assessment.

Zinc fever in a painter and varnisher: a case report.

BACKGROUND: Zinc fever is well described in medical literature, particularly in workers after handling zinc-containing materials at high temperatures e.g., in the welding of hot-dip galvanized steel sheets. It is not known whether zinc fever also occurs at low temperatures. CASE PRESENTATION: We present the case of a 33-year-old Caucasian atopic painter and varnisher with work-related dyspnea, sweating, as well as multiple occurrences of fever. He was sent to Institute for Prevention and Occupational medicine of the German Social Accident Insurance, Institute of the Ruhr-Universität Bochum (IPA) for the evaluation of isocyanate asthma, but an inhalative challenge with hexamethylene diisocyanate was negative. Since symptoms were closely related to the use of zinc coatings at room temperature without adequate protective measures, the diagnosis of zinc fever was made. After exposure cessation the worker immediately became symptom-free. The work as painter and varnisher may be associated with various exposures to hazardous substances. Besides solvents, epoxy compounds and isocyanates, which can cause obstructive respiratory diseases; additionally, zinc-containing agents should be considered as health hazards. CONCLUSIONS: This case demonstrates that zinc fever may occur also after application of zinc coatings by spray painting at low temperatures.

An Extensive Study of the Influence of Key Flow Variables on Printed Line Quality Outcomes during Aerosol Jet Printing Using Coupled Three-Dimensional Numerical Models.

A three-dimensional (3D) numerical model was developed to explore the intricate aerodynamic mechanisms associated with aerosol jet printing (AJP). The proposed approach integrates computational fluid dynamics and discrete phase modeling, offering a comprehensive understanding of the deposition mechanisms of the AJP process. Initially, numerical solutions of the governing equations were obtained under the assumptions of compressible and laminar flows, facilitating an analysis of certain key flow variables, in this case, the sheath gas flow rate and carrier gas flow rate across the fluid domain. Subsequently, incorporating a Lagrangian discrete phase model allowed a detailed examination of the droplet behavior after nozzle ejection, considering the influence of the Saffman lift force. Finally, experiments were performed to elucidate the influence of key flow variables on the printed width. Generally, the measured printed line morphology and corresponding line electrical performance exhibited close conformity with the numerical model, demonstrating that the proposed numerical model is important for making well-informed decisions during process optimization.

Deciphering the seasonal dynamics of multifaceted aerosol-ozone interplay: Implications for air quality management in Eastern China.

We employed an enhanced WRF-Chem to investigate the discrete mechanisms of aerosol-radiation-feedback (ARF), extinction-photochemistry (AEP), and heterogeneous-reactions (AHR) across different seasons in eastern China, aiming to assess the synergistic effects arising from the simultaneous operation of multiple processes on O3 and PM2.5. Our findings demonstrated that ARF fostered the accumulation of pollutants and moisture, initiating two distinct feedback mechanisms concerning O3. The elevation in the NO/NO2 ratio amplified O3 consumption. Increased near-surface moisture diminished upper-level cloud formation, thereby enhancing photolysis rates and O3 photochemical production. The pronounced impact of heightened NO/NO2 on O3 led to a decrease of 0.1-2.7 ppb. When decoupled from ARF, AEP led to a more significant reduction in photolysis rates, resulting in declines in both O3 and PM2.5, except for an anomalous increase observed in summer, with O3 increasing by 1.6 ppb and PM2.5 by 2.5 µg m-3. The heterogeneous absorption of hydroxides in spring, autumn, and winter predominantly governed the AHR-induced variation of O3, leading to a decrease in O3 by 0.7-1 ppb. Conversely, O3 variations in summer were primarily dictated by O3-sensitive chemistry, with heterogeneous absorption of NOy catalyzing a decrease of 2.4 ppb in O3. Furthermore, AHR accentuated PM2.5 by facilitating the formation of fine sulfates and ammonium while impeding nitrate formation. In summer, the collective impact of ARF, AEP, and AHR (ALL) led to a substantial reduction of 6.2 ppb in O3, alleviating the secondary oxidation of PM2.5 and leading to a decrease of 0.3 µg m-3 in PM2.5. Conversely, albeit aerosol substantially depleted O3 by 0.4-4 ppb through their interactions except for summer, aerosol feedback on PM2.5 was more pronounced, resulting in a significant increase of 1.7-6.1 µg m-3 in PM2.5. Our study underscored the seasonal disparities in the ramifications of multifaceted aerosol-ozone interplay on air quality.

Dynamic swatch testing of liquid aerosols in a laboratory-sized recirculating wind tunnel.

Chemical warfare agents (CWAs) pose a threat as gaseous substances and as liquid aerosols, necessitating chemical warfare-protective clothing for soldiers. The paramount consideration lies in the effectiveness of the clothing as a barrier against the pertinent CWAs. This paper presents a dynamic swatch test method aimed at evaluating the performance of such clothing against liquid-phase aerosol penetration. Central to the methodology is a specialized test cell designed to rotate to the left and right, integrated within a laboratory wind tunnel, replicating mission-relevant conditions with varying wind speeds. Utilizing di(2-ethylhexyl) sebacate particles as liquid aerosols, tests were conducted at wind speeds of 1.0, 3.0, and 5.0 m/s. Penetration assessment relied on analyzing particle counts downstream and upstream of the fabric, with preliminary studies showing that higher wind speeds and fabric air permeabilities increase penetration at an equivalent face velocity of 5.0 cm/s. Interestingly, penetration decreased when fabric samples were subjected to rotation. The system and methodology devised demonstrated consistent and repeatable results, offering valuable insights into optimizing the effectiveness of chemical warfare-protective clothing. This research contributes to advancing methodologies for testing protective clothing, crucial for ensuring the safety of military personnel in hazardous environments.

Dynamics of nanocluster aerosol in the indoor atmosphere during gas cooking.

Nanocluster aerosol (NCA: particles in the size range of 1-3 nm) are a critically important, yet understudied, class of atmospheric aerosol particles. NCA efficiently deposit in the human respiratory system and can translocate to vital organs. Due to their high surface area-to-mass ratios, NCA are associated with a heightened propensity for bioactivity and toxicity. Despite the human health relevance of NCA, little is known regarding the prevalence of NCA in indoor environments where people spend the majority of their time. In this study, we quantify the formation and transformation of indoor atmospheric NCA down to 1 nm via high-resolution online nanoparticle measurements during propane gas cooking in a residential building. We observed a substantial pool of sub-1.5 nm NCA in the indoor atmosphere during cooking periods, with aerosol number concentrations often dominated by the newly formed NCA. Indoor atmospheric NCA emission factors can reach up to ∼1016 NCA/kg-fuel during propane gas cooking and can exceed those for vehicles with gasoline and diesel engines. Such high emissions of combustion-derived indoor NCA can result in substantial NCA respiratory exposures and dose rates for children and adults, significantly exceeding that for outdoor traffic-associated NCA. Combustion-derived indoor NCA undergo unique size-dependent physical transformations, strongly influenced by particle coagulation and condensation of low-volatility cooking vapors. We show that indoor atmospheric NCA need to be measured directly and cannot be predicted using conventional indoor air pollution markers such as PM2.5 mass concentrations and NO x (NO + NO2) mixing ratios.

Aerosol Delivery Efficiency With High-Flow Nasal Cannula Therapy in Neonatal, Pediatric, and Adult Nasal Upper-Airway and Lung Models.

BACKGROUND: High-flow nasal cannula (HFNC) systems employ different methods to provide aerosol to patients. This study compared delivery efficiency, particle size, and regional deposition of aerosolized bronchodilators during HFNC in neonatal, pediatric, and adult upper-airway and lung models between a proximal aerosol adapter and distal aerosol circuit chamber. METHODS: A filter was connected to the upper airway to a spontaneously breathing lung model. Albuterol was nebulized using the aerosol adapter and circuit at different clinical flow settings. The aerosol mass deposited in the upper airway and lung was quantified. Particle size was measured with a laser diffractometer. Regional deposition was assessed with a gamma camera at each nebulizer location and patient model with minimum flow settings. RESULTS: Inhaled lung doses ranged from 0.2-0.8% for neonates, 0.2-2.2% for the small child, and 0.5-5.2% for the adult models. Neonatal inhaled lung doses were not different between the aerosol circuit and adapter, but the aerosol circuit showed marginally greater lung doses in the pediatric and adult patient models. Impacted aerosols and condensation in the non-heated HFNC and aerosol delivery components contributed to the dispersion of coarse liquid droplets, high deposition (11-44%), and occlusion of the supine neonatal upper airway. In contrast, the upright pediatric and adult upper-airway models had minimal deposition (0.3-7.0%) and high fugitive losses (∼24%) from liquid droplets leaking out of the nose. The high impactive losses in the aerosol adapter (56%) were better contained than in the aerosol circuit, resulting in less cannula sputter (5% vs 22%), fewer fugitive losses (18% vs 24%), and smaller inhaled aerosols (5 µm vs 13 µm). CONCLUSIONS: The inhaled lung dose was low (1-5%) during HFNC. Approaches that streamline aerosol delivery are needed to provide safe and effective therapy to patients receiving aerosolized medications with this HFNC system.

Cryomilled electrospun nanofiber mats containing d-mannitol exhibit suitable for aerosol delivery of proteins.

Dry powder inhalers (DPIs) are the first choice for inhalation drug development. However, some conventional DPI formulation processes require heating, which may damage high molecular weight drugs such as proteins and nucleic acids. In this study, we propose a novel DPI preparation process that avoids the use of heat. Dry powders were prepared by cryomilling nanofiber mats composed of polyvinyl alcohol, D(-)-mannitol (Man), and α-chymotrypsin (α-Chy) as the model drug using the electrospinning method. The addition of Man conferred high dispersibility and excellent in vitro aerosol performance to the nanofiber mat powder in a very short milling time (less than 0.5 min) as assessed using the Andersen cascade impactor. Powders were classified according to the degree of friability, and among these, nanofiber mats containing 15 % Man and milled for 0.25 min exhibited the highest aerosol performance. Nanofiber mats containing Man milled for less than 0.5 min also exhibited greater α-Chy enzymatic activity than a nebulized α-Chy solution. Furthermore, single inhalation induced no significant lung tissue damage as evidenced by lactate dehydrogenase activity assays of mouse bronchoalveolar lavage fluid. This novel DPI formulation process may facilitate the safe and efficient inhalational delivery of therapeutic proteins.

A Comparative Investigation of Aerosol Generation and Exposure Risk During Access Cavity Preparation With or Without Rubber Dam Application.

BACKGROUND: Aerosols generated during dental procedures have taken the forefront of discussion in dentistry. Due to the nature of their work, dental professionals face a significant risk of exposure to various biological hazards, such as saliva, blood, aerosols, and droplets. Aerosols, which are tiny particles with a diameter of less than 50µm, have a unique property that allows them to stay suspended in the air for extended periods. This is primarily due to their small size and lightweight nature which makes them highly susceptible to air currents and prevents them from quickly settling down. As a result, these aerosols can linger in the atmosphere, creating a potential risk for respiratory infections. AIM: The aim is to evaluate and compare the efficacy of rubber dams in preventing aerosols generated cross-contamination. METHODS AND MATERIAL: This in-vivo experimental study comprised 60 individuals who were suggested for root canal treatment in the mandibular first permanent molar tooth. The passive air sampling technique using "settle plates" was applied to investigate microbial fallout during access opening with and without rubber dam application. Sheep blood agar plates were used to do the colony forming unit (CFU) count. All patients were randomly divided into two groups comprising 30 patients each based on usage of rubber dam application or not, i.e., Group I: Without rubber dam application and Group II: With rubber dam application. RESULTS: Using a rubber dam while performing an endodontic procedure significantly impacts decreased aerosol generation at 0.5-m and 2-m distances than its counterpart with a p-value < 0.01. CONCLUSION: Using a rubber dam during endodontic procedures reduces the likelihood of aerosol generation, thereby decreasing the risk of cross-contamination and lowering the susceptibility of dental professionals to respiratory illnesses.

Aerosol exposure at air-liquid-interface (AE-ALI) in vitro toxicity system characterisation: Particle deposition and the importance of air control responses.

Experimental systems allowing aerosol exposure (AE) of cell cultures at the air-liquid-interface (ALI) are increasingly being used to assess the toxicity of inhaled contaminants as they are more biomimetic than standard methods using submerged cultures, however, they require detailed characterisation before use. An AE-ALI system combining aerosol generation with a CULTEX® exposure chamber was characterised with respect to particle deposition and the cellular effects of filtered air (typical control) exposures. The effect of system parameters (electrostatic precipitator voltage, air flowrate to cells and insert size) on deposition efficiency and spatial distribution were investigated using ICP-MS and laser ablation ICP-MS, for an aerosol of CeO2 nanoparticles. Deposition varied with conditions, but appropriate choice of operating parameters produced broadly uniform deposition at suitable levels. The impact of air exposure duration on alveolar cells (A549) and primary small airway epithelial cells (SAECs) was explored with respect to LDH release and expression of selected genes. Results indicated that air exposures could have a significant impact on cells (e.g., cytotoxicity and expression of genes, including CXCL1, HMOX1, and SPP1) at relatively short durations (from 10 mins) and that SAECs were more sensitive. These findings indicate that detailed system characterisation is essential to ensure meaningful results.

HONO chemistry and its impact on the atmospheric oxidizing capacity over the Indo-Gangetic Plain.

Chemical processes involving nitrous acid (HONO) play a pivotal role as it is a notable source of hydroxyl (∙OH) radicals, influencing the oxidation capacity of the atmosphere. We conduct a comprehensive investigation into the temporal dynamics of HONO, other gases (nitrogen oxides (NOx), ozone (O3), ammonia (NH3), sulphur dioxide (SO2), and nitric acid (HNO3)), particulate matter (PM2.5), and meteorological parameters using measurements that took place during the Winter Fog Experiment (WiFEx) campaign in Delhi, India, during the winter of 2017-2018. Remarkable day-to-day variations in HONO concentrations are observed, with the peak value reaching 54.5 µg m-3 during a fog event. This coincides with elevated levels of sulfate and nitrate in aerosols, underscoring the significant role of heterogeneous fog chemistry in HONO production. We investigated HONO sources and sinks during fog periods by using a photochemical box model. The model shows that the gas-phased chemistry of HONO predicts concentrations lower by an order of magnitude compared to observations (peaking at 0.60 µg m-3 compared to the average observed value of 7.00 µg m-3). The calculated production rates of HONO from observations for daytime to nighttime peaks are 3.10 µg m-3 h-1 (1.1 × 107 molecules cm3 s-1) and 2.00 µg m-3 h-1 (7.1 × 106 molecules cm3 s-1), respectively. This shows the existence of an undefined heterogeneous reaction pathway for HONO production. At the peak of HONO concentration, we estimated an ∙OH formation rate of 9.4 × 107 molecules cm3 s-1 due to the photolysis of HONO, which is much higher than the production of HONO from the reaction of O1D with H2O. This underscores the predominant role of HONO photolysis as the primary source of ∙OH radicals compared to other pathways and highlights the significant role of HONO chemistry in influencing atmospheric oxidation capacity.

Substrate-induced strain in molybdenum disulfide grown by aerosol-assisted chemical vapor deposition.

Transition metal dichalcogenides have been extensively studied in recent years because of their fascinating optical, electrical, and catalytic properties. However, low-cost, scalable production remains a challenge. Aerosol-assisted chemical vapor deposition (AACVD) provides a new method for scalable thin film growth. In this study, we demonstrate the growth of molybdenum disulfide (MoS2) thin films using AACVD method. This method proves its suitability for low-temperature growth of MoS2thin films on various substrates, such as glass, silicon dioxide, quartz, silicon, hexagonal boron nitride, and highly ordered pyrolytic graphite. The as-grown MoS2shows evidence of substrate-induced strain. The type of strain and the morphology of the as-grown MoS2highly depend on the growth substrate's surface roughness, crystallinity, and chemical reactivity. Moreover, the as-grown MoS2shows the presence of both direct and indirect band gaps, suitable for exploitation in future electronics and optoelectronics.