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Particle and Fibre Toxicology Feb 2024Airborne environmental and engineered nanoparticles (NPs) are inhaled and deposited in the respiratory system. The inhaled dose of such NPs and their deposition location...
BACKGROUND
Airborne environmental and engineered nanoparticles (NPs) are inhaled and deposited in the respiratory system. The inhaled dose of such NPs and their deposition location in the lung determines their impact on health. When calculating NP deposition using particle inhalation models, a common approach is to use the bulk material density, ρ, rather than the effective density, ρ. This neglects though the porous agglomerate structure of NPs and may result in a significant error of their lung-deposited dose and location.
RESULTS
Here, the deposition of various environmental NPs (aircraft and diesel black carbon, wood smoke) and engineered NPs (silica, zirconia) in the respiratory system of humans and mice is calculated using the Multiple-Path Particle Dosimetry model accounting for their realistic structure and effective density. This is done by measuring the NP ρ which was found to be up to one order of magnitude smaller than ρ. Accounting for the realistic ρ of NPs reduces their deposited mass in the pulmonary region of the respiratory system up to a factor of two in both human and mouse models. Neglecting the ρ of NPs does not alter significantly the distribution of the deposited mass fractions in the human or mouse respiratory tract that are obtained by normalizing the mass deposited at the head, tracheobronchial and pulmonary regions by the total deposited mass. Finally, the total deposited mass fraction derived this way is in excellent agreement with those measured in human studies for diesel black carbon.
CONCLUSIONS
The doses of inhaled NPs are overestimated by inhalation particle deposition models when the ρ is used instead of the real-world effective density which can vary significantly due to the porous agglomerate structure of NPs. So the use of realistic ρ, which can be measured as described here, is essential to determine the lung deposition and dosimetry of inhaled NPs and their impact on public health.
Topics: Humans; Mice; Animals; Particle Size; Inhalation Exposure; Lung; Soot; Nanoparticles; Carbon
PubMed: 38368385
DOI: 10.1186/s12989-024-00567-9 -
ACS Omega Feb 2024This study investigates the utilization of an α-MnO/nanocarbon ball (NCB) additive to enhance the performance of second-, third-, and fourth-generation biodiesels...
This study investigates the utilization of an α-MnO/nanocarbon ball (NCB) additive to enhance the performance of second-, third-, and fourth-generation biodiesels (SSGB, PVB, and GMCB). Various tests including XRD, XPS, TEM, HRTEM, BET, torque and power measurements, EGT, BTE, emissions analysis (CO, CO, HC, soot, and NOx), and BSFC were conducted. The combination of GMCB5N50 with α-MnO/NCB yielded the highest torque (35.77 N m) and power (6.47 kW), indicating an improved engine performance. GMCB5N50 exhibited efficient combustion with a peak pressure of 76.04 bar. The nanoadditive also demonstrated significant reduction in BSFC, achieving up to 34% improvement in fuel efficiency. When GMCB20N50 was used, the highest BTE values were observed, reaching approximately 39.5%. EGT values for GMCB5N50 were only slightly elevated compared to pure diesel. Notably, GMCB20N50 showcased substantial decreases in emissions, including carbon dioxide (CO: 55% reduction), carbon monoxide (CO: 35% reduction), hydrocarbons (HC: 58% reduction), and soot (98% reduction), indicating a promising direction for the development of low-emission alternative fuels. The investigation of the effects of the oxygen lattice, surface area, and oxygen adsorption on engine performance and emission reduction revealed their positive contributions. These findings highlight the potential of the studied α-MnO/NCB additive for improving biodiesel performance and advancing the development of sustainable and environmentally friendly fuels.
PubMed: 38343977
DOI: 10.1021/acsomega.3c05848 -
Sensors (Basel, Switzerland) Feb 2024Black carbon (BC) or soot contains ultrafine combustion particles that are associated with a wide range of health impacts, leading to respiratory and cardiovascular...
Black carbon (BC) or soot contains ultrafine combustion particles that are associated with a wide range of health impacts, leading to respiratory and cardiovascular diseases. Both long-term and short-term health impacts of BC have been documented, with even low-level exposures to BC resulting in negative health outcomes for vulnerable groups. Two aethalometers-AethLabs MA350 and Aerosol Magee Scientific AE33-were co-located at a Utah Division of Air Quality site in Bountiful, Utah for just under a year. The aethalometer comparison showed a close relationship between instruments for IR BC, Blue BC, and fossil fuel source-specific BC estimates. The biomass source-specific BC estimates were markedly different between instruments at the minute and hour scale but became more similar and perhaps less-affected by high-leverage outliers at the daily time scale. The greater inter-device difference for biomass BC may have been confounded by very low biomass-specific BC concentrations during the study period. These findings at a mountainous, high-elevation, Greater Salt Lake City Area site support previous study results and broaden the body of evidence validating the performance of the MA350.
Topics: Air Pollutants; Soot; Carbon; Environmental Monitoring; Particulate Matter; Aerosols
PubMed: 38339682
DOI: 10.3390/s24030965 -
Nanomaterials (Basel, Switzerland) Feb 2024Wettability, typically estimated through the contact angle, is a fundamental property of surfaces with wide-ranging implications in both daily life and industrial...
Wettability, typically estimated through the contact angle, is a fundamental property of surfaces with wide-ranging implications in both daily life and industrial processes. Recent scientific interest has been paid to the surfaces exhibiting extreme wettability: superhydrophobic and superhydrophilic surfaces, characterized by high water repellency and exceptional water wetting, respectively. Both chemical composition and morphology play a role in the determination of the wettability "performance" of a surface. To tune surface-wetting properties, we considered coatings of carbon nanoparticles (CNPs) in this study. They are a new class of nanomaterials synthesized in flames whose chemistry, dimension, and shape depend on combustion conditions. For the first time, we systematically studied the wettability of CNP coatings produced in a controlled rich ethylene/air flame stabilized over a McKenna burner. A selected substrate was intermittently inserted in the flame at 15 mm above the burner to form a thin coating thanks to a thermophoretic-driven deposition mechanism. The chemical-physical quality and the deposed quantity of the CNPs were varied by opportunely combing the substrate flame insertion number (from 1 to 256) and the carbon-to-oxygen ratio, C/O (from 0.67 to 0.87). The wettability of the coatings was evaluated by measuring the contact angle, CA, with the sessile drop method. When the C/O = 0.67, the CNPs were nearly spherical, smaller than 8 nm, and always generated hydrophilic coatings (CA < 35°). At higher C/O ratios, the CNPs reached dimensions of 100 nm, and fractal shape aggregates were formed. In this case, either hydrophilic (CA < 76°) or superhydrophobic (CA ~166°) behavior was observed, depending on the number of carbon nanoparticles deposed, i.e., film thickness. It is known that wettability is susceptible to liquid surface tension, and therefore, tests were conducted with different fluids to establish a correlation between the flame conditions and the nanostructure of the film. This method offers a fast and simple approach to determining mesoscale information for coating roughness and topographical homogeneity/inhomogeneity of their surfaces.
PubMed: 38334572
DOI: 10.3390/nano14030301 -
ACS Omega Jan 2024Wall impingement, particularly liquid-wall impingement, has been demonstrated to be one of the critical causes of combustion deterioration in plateau diesel engines....
Wall impingement, particularly liquid-wall impingement, has been demonstrated to be one of the critical causes of combustion deterioration in plateau diesel engines. Obviously, the complexity of wall impingement is exacerbated by the plateau scenario. However, fundamental studies specifically dedicated to this phenomenon are still inconclusive and insufficiently detailed, obviating the feasibility of the targeted design and optimization of diesel engines operating in regions with different altitudes. Consequently, the second part of this investigation, presented in this work, focused on the detailed physical and chemical processes of impinging spray combustion under different altitude conditions. A wall impingement system was designed to generate an impinging spray flame. The impingement distance was varied from 77 to 37 mm to cover different situations of wall impingement. The liquid spray, ignition, and combustion processes were visualized in detail by using different optical diagnostics. The results showed that the variation of the liquid length with the impingement distance was mainly dependent on the liquid impingement under the same altitude condition. The effect of the impingement distance on the ignition distance was more sensitive to the altitude. The quantitative analysis of the flame natural luminosity confirmed the decisive effect of the impinging flame morphology on the ambient entrainment and fuel-air mixing under different altitude conditions, and it also revealed that there was an optimal impingement distance under identical altitude conditions to achieve minimum soot emissions. And interestingly, the optimal impingement distance increased with altitude. Finally, the spray combustion processes of an impinging diesel jet were determined to occur in four typical regions, upon which a schematic diagram depicting the flame structure of an impinging diesel jet was proposed to phenomenologically describe the role of altitude in impinging spray combustion processes. Based on this, an attempt was made to explore some new perspectives beyond the popular solutions to recover and improve the performance of plateau diesel engines.
PubMed: 38313479
DOI: 10.1021/acsomega.3c07357 -
Environmental Science & Technology Feb 2024With the increased occurrences of wildfires worldwide, there has been an increase in scientific interest surrounding the chemistry of fire-derived "black" carbon (BC)....
With the increased occurrences of wildfires worldwide, there has been an increase in scientific interest surrounding the chemistry of fire-derived "black" carbon (BC). Traditionally, wildfire research has assumed that condensed aromatic carbon (ConAC) is produced via combustion, and thus, ConAC is equated to BC. However, the lack of correlations between ConAC in soils or rivers and wildfire history suggests that ConAC may be produced non-pyrogenically. Here, we show quantitative evidence that this occurs during the oxidation of biomass with environmentally ubiquitous hydroxyl radicals. Pine wood boards exposed to iron nails and natural weather conditions for 12 years yielded a charcoal-like ConAC-rich material. ConAC was also produced during laboratory oxidations of pine, maple, and brown-rotted oak woods, as well as algae, corn root, and tree bark. Back-of-the-envelope calculations suggest that biomass oxidation could be producing massive non-pyrogenic ConAC fluxes to terrestrial and aquatic environments. These estimates (e.g., 163-182 Tg-ConAC/year to soils) are much higher than the estimated pyrogenic "BC" fluxes (e.g., 128 Tg-ConAC/year to soils) implying that environmental ConAC is primarily non-pyrogenic. This novel perspective suggests that wildfire research trajectories should shift to assessing non-pyrogenic ConAC sources and fluxes, developing new methods for quantifying true BC, and establishing a new view of ConAC as an intermediate species in the biogeochemical processing of biomass during soil humification, aquatic photochemistry, microbial degradation, or mineral-organic matter interactions. We also advise against using BC or pyrogenic carbon (pyC) terminologies for ConAC measured in environmental matrices, unless a pyrogenic source can be confidently assigned.
Topics: Biomass; Carbon; Charcoal; Fires; Soot; Soil
PubMed: 38294931
DOI: 10.1021/acs.est.3c05448 -
Burns : Journal of the International... May 2024In South Africa, fire-related deaths are common, particularly within dense informal housing settlements. Published data on deaths from fire incidents in Cape Town is...
BACKGROUND
In South Africa, fire-related deaths are common, particularly within dense informal housing settlements. Published data on deaths from fire incidents in Cape Town is sparse. Additionally, little emphasis has been placed on the role of toxicological investigations in these deaths, despite the known risk of alcohol and drug impairment to burn injury.
METHODS
A retrospective, descriptive analysis of post-mortem case reports from Salt River Mortuary was conducted to investigate all deaths in which fires were involved in the west metropole of Cape Town, between 2006 to 2018. Demographic, circumstantial, and toxicological data were analyzed using R software.
RESULTS
In total 1370 fire deaths occurred over 13 years, with a mean of 106 (SD ± 18) cases per annum (≈3% of the annual caseload and a mortality rate of 5.5 per 100,000). Males (70.4%), adults (mean=30.7 years), and toddlers (1-4 years old) were notably at risk. Deaths typically occurred in the early morning (00h00 - 06h00) (45.7%), during winter (32.1%), and in lower socioeconomic areas with highly dense informal settlements (65.6%), with 29% of deaths occurring in multi-fatality incidents. Ethanol was detected (≥0.01 g/100 mL) in 55.1% of cases submitted for analysis (71.5%), with a mean of 0.18 g/100 mL, and with 93.8% of positive cases > 0.05 g/100 mL. Carboxyhaemoglobin (COHb) analysis was requested in 76.4% of cases, with 57% of cases having a %COHb of ≥ 20%. Toxicology results (for drugs other than ethanol) from the national laboratory were outstanding in 34.4% of the cases at the conclusion of the study. BAC and %COHb were significantly higher in deaths from burns and smoke inhalation (usually accidents) than deaths from combined trauma and burns (typically homicides). Fire deaths with high COHb levels were more likely to display cherry-red discoloration (OR=3.1) and soot in the airways (OR=2.7) at autopsy.
CONCLUSION
This article provides an updated description of fire deaths in the west metropole of Cape Town. The importance of BAC and COHb testing in these cases was noted, and the authors call for an investigation of the role of drug impairment (specifically frequently misused drugs methamphetamine and methaqualone) as a risk factor in these deaths. Areas of high-density informal settlements, where open flames are used to heat, light, and cook, were noted as high risk.
Topics: Humans; South Africa; Retrospective Studies; Male; Adult; Female; Burns; Fires; Infant; Child, Preschool; Child; Middle Aged; Adolescent; Young Adult; Carboxyhemoglobin; Aged; Blood Alcohol Content; Methamphetamine; Age Distribution; Ethanol; Sex Distribution; Smoke Inhalation Injury; Carbon Monoxide Poisoning; Seasons; Aged, 80 and over; Substance-Related Disorders; Central Nervous System Depressants
PubMed: 38290966
DOI: 10.1016/j.burns.2024.01.001 -
Environmental Pollution (Barking, Essex... Mar 2024Household air pollution (HAP) from cooking with solid fuels used during pregnancy has been associated with adverse pregnancy outcomes. The Household Air Pollution... (Randomized Controlled Trial)
Randomized Controlled Trial
Effects of a liquefied petroleum gas stove intervention on stillbirth, congenital anomalies and neonatal mortality: A multi-country household air pollution intervention network trial.
Household air pollution (HAP) from cooking with solid fuels used during pregnancy has been associated with adverse pregnancy outcomes. The Household Air Pollution Intervention Network (HAPIN) trial was a randomized controlled trial that assessed the impact of a liquefied petroleum gas (LPG) stove and fuel intervention on health in Guatemala, India, Peru, and Rwanda. Here we investigated the effects of the LPG stove and fuel intervention on stillbirth, congenital anomalies and neonatal mortality and characterized exposure-response relationships between personal exposures to fine particulate matter (PM), black carbon (BC) and carbon monoxide (CO) and these outcomes. Pregnant women (18 to <35 years of age; gestation confirmed by ultrasound at 9 to <20 weeks) were randomly assigned to intervention or control arms. We monitored these fetal and neonatal outcomes and personal exposure to PM, BC and CO three times during pregnancy, we conducted intention-to-treat (ITT) and exposure-response (E-R) analyses to determine if the HAPIN intervention and corresponding HAP exposure was associated with the risk of fetal/neonatal outcomes. A total of 3200 women (mean age 25.4 ± 4.4 years, mean gestational age at randomization 15.4 ± 3.1 weeks) were included in this analysis. Relative risks for stillbirth, congenital anomaly and neonatal mortality were 0.99 (0.60, 1.66), 0.92 (95 % CI 0.52, 1.61), and 0.99 (0.54, 1.85), respectively, among women in the intervention arm compared to controls in an ITT analysis. Higher mean personal exposures to PM, CO and BC during pregnancy were associated with a higher, but statistically non-significant, incidence of adverse outcomes. The LPG stove and fuel intervention did not reduce the risk of these outcomes nor did we find evidence supporting an association between personal exposures to HAP and stillbirth, congenital anomalies and neonatal mortality.
Topics: Adult; Female; Humans; Infant, Newborn; Pregnancy; Young Adult; Air Pollution; Air Pollution, Indoor; Cooking; Infant Mortality; Particulate Matter; Petroleum; Soot; Stillbirth; Adolescent
PubMed: 38286258
DOI: 10.1016/j.envpol.2024.123414 -
Constructing transferable and interpretable machine learning models for black carbon concentrations.Environment International Feb 2024Black carbon (BC) has received increasing attention from researchers due to its adverse health effects. However, in-situ BC measurements are often not included as a...
Black carbon (BC) has received increasing attention from researchers due to its adverse health effects. However, in-situ BC measurements are often not included as a regulated variable in air quality monitoring networks. Machine learning (ML) models have been studied extensively to serve as virtual sensors to complement the reference instruments. This study evaluates and compares three white-box (WB) and four black-box (BB) ML models to estimate BC concentrations, with the focus to show their transferability and interpretability. We train the models with the long-term air pollutant and weather measurements in Barcelona urban background site, and test them in other European urban and traffic sites. Despite the difference in geographical locations and measurement sites, BC correlates the strongest with particle number concentration of accumulation mode (PN, r = 0.73-0.85) and nitrogen dioxide (NO, r = 0.68-0.85) and the weakest with meteorological parameters. Due to its similarity of correlation behaviour, the ML models trained in Barcelona performs prominently at the traffic site in Helsinki (R = 0.80-0.86; mean absolute error MAE = 3.90-4.73 %) and at the urban background site in Dresden (R = 0.79-0.84; MAE = 4.23-4.82 %). WB models appear to explain less variability of BC than BB models, long short-term memory (LSTM) model of which outperforms the rest of the models. In terms of interpretability, we adopt several methods for individual model to quantify and normalize the relative importance of each input feature. The overall static relative importance commonly used for WB models demonstrate varying results from the dynamic values utilized to show local contribution used for BB models. PN and NO on average have the strongest absolute static contribution; however, they simultaneously impact the estimation positively and negatively at different sites. This comprehensive analysis demonstrates that the possibility of these interpretable air pollutant ML models to be transfered across space and time.
Topics: Environmental Monitoring; Nitrogen Dioxide; Air Pollutants; Air Pollution; Soot; Machine Learning; Carbon; Particulate Matter
PubMed: 38286044
DOI: 10.1016/j.envint.2024.108449 -
Scientific Reports Jan 2024The parallel measurements of wavelength dependent optical absorption, particle number size distribution have made by a multi wavelength photoacoustic spectrometer...
The parallel measurements of wavelength dependent optical absorption, particle number size distribution have made by a multi wavelength photoacoustic spectrometer (4λ-PAS) and scanning mobility particle sizer (SMPS) respectively at different modes of a diesel engine using two different types of fuel. The thermal evolution of the emission was also investigated using posterior temperature treatment of emission. The bimodal size distribution of emitted particles at a set reference temperature has been observed regardless of the applied fuel at idle. However, the emitted particulate assembly had lognormal size distribution falls into the accumulation mode at all other defined engine modes and both fuel types. The total number- and volume concentration (TNC and TVC) showed retrograde tendency with the increasing torque and rpm independently of the applied fuel types. The TNC values decreased up to 50% for both fuels with engine operation changes from idle engine mode(em#1) to low engine mode(em#2). With further increase in torque and rpm of engine, the change in TNC is negligible. On the other hand, the TVC remains more or less the same for idle to low engine mode transition and increased more than 60% for high mode (em#3) transition. The Optical Absorption Coefficient (OAC) values measured at the operational wavelengths of the 4λ-PAS instrument decreased at all wavelengths with increasing rpm and torque. The wavelength dependency quantified by Aerosol Ängström Exponent (AAE) was applied here for qualitative analysis of the carbonaceous emission and showed decreased values towards the higher engine speed and torque output of the engine. The proposed technique can be used as real-time, precise and accurate measurement of light absorption by DPM aerosols, which opens up novel possibilities for the volatility and thermal evolution investigation of diesel emissions.
PubMed: 38278878
DOI: 10.1038/s41598-024-52832-8