Explore the vast range of titles available.

The elongated microgravity flame thins the flame's upper boundary, increasing the flame's surface-to-volume ratio and making it easier for unconsumed soot particles to escape into the neighboring gas sweeping the microgravityflame's surface. [...]the fuel molecules breach the flame only to later congeal and form soot.

Particle transfer across the placenta has been suggested but to date, no direct evidence in real-life, human context exists. Here we report the presence of black carbon (BC) particles as part of combustion-derived particulate matter in human placentae using white-light generation under femtosecond pulsed illumination. BC is identified in all screened placentae, with an average (SD) particle count of 0.95 × 10 4 (0.66 × 10 4 ) and 2.09 × 10 4 (0.9 × 10 4 ) particles per mm 3 for low and high exposed mothers, respectively. Furthermore, the placental BC load is positively associated with mothers’ residential BC exposure during pregnancy (0.63–2.42 µg per m 3 ). Our finding that BC particles accumulate on the fetal side of the placenta suggests that ambient particulates could be transported towards the fetus and represents a potential mechanism explaining the detrimental health effects of pollution from early life onwards. Exposure to air pollution during pregnancy has been associated with impaired birth outcomes. Here, Bové et al. report evidence of black carbon particle deposition on the fetal side of human placentae, including at early stages of pregnancy, suggesting air pollution could affect birth outcome through direct effects on the fetus.

Background Traffic-related air pollution may contribute to cardiovascular morbidity. In urban areas, exposures during physical activity are of interest owing to increased breathing rates and close proximity to vehicle emissions. Methods We conducted a cross-over study among 53 healthy non-smoking women in Montreal, Canada during the summer of 2013. Women were exposed to traffic pollutants for 2-hours on three separate occasions during cycling on high and low-traffic routes as well as indoors. Personal air pollution exposures (PM 2.5 , ultrafine particles (UFP), black carbon, NO 2 , and O 3 ) were evaluated along each route and linear mixed-effects models with random subject intercepts were used to estimate the impact of air pollutants on acute changes in blood pressure, heart rate variability, and micro-vascular function in the hours immediately following exposure. Single and multi-pollutant models were examined and potential effect modification by mean regional air pollution concentrations (PM 2.5 , NO 2 , and O 3 ) was explored for the 24-hour and 5-day periods preceding exposure. Results In total, 143 exposure routes were completed. Each interquartile increase (10,850/cm 3 ) in UFP exposure was associated with a 4.91% (95% CI: -9.31, -0.512) decrease in reactive hyperemia index (a measure of micro-vascular function) and each 24 ppb increase in O 3 exposure corresponded to a 2.49% (95% CI: 0.141, 4.84) increase in systolic blood pressure and a 3.26% (95% CI: 0.0117, 6.51) increase in diastolic blood pressure 3-hours after exposure. Personal exposure to PM 2.5 was associated with decreases in HRV measures reflecting parasympathetic modulation of the heart and regional PM 2.5 concentrations modified these relationships (p < 0.05). In particular, stronger inverse associations were observed when regional PM 2.5 was higher on the days prior to the study period. Regional PM 2.5 also modified the impact of personal O 3 on the standard deviation of normal to normal intervals (SDNN) (p < 0.05): a significant inverse relationship was observed when regional PM 2.5 was low prior to study periods and a significant positive relationship was observed when regional PM 2.5 was high. Conclusion Exposure to traffic pollution may contribute to acute changes in blood pressure, autonomic and micro-vascular function in women. Regional air pollution concentrations may modify the impact of these exposures on autonomic function.

Soot-catalyst contact represents the main critical issue for an effective regeneration of catalytic (i.e., catalyst-coated) diesel particulate filters (DPFs). Most of the literature reviews on this topic have mainly been focused on studies dealing with powdered soot-catalyst mixtures. Although the results obtained on powders surely provide significant indications, especially in terms of intrinsic activity of materials towards soot oxidation, they cannot be directly extended to DPFs due to completely different soot-catalyst contact conditions generated during filtration and subsequent regeneration. In this work, attention is devoted to catalytic DPFs and, more specifically, studies on both catalyst dispersion and soot distribution inside the filter are critically reviewed from the perspective of soot-catalyst contact optimization. The main conclusion drawn from the literature analysis is that, in order to fully exploit the potential of catalytic DPFs in soot abatement, both a widespread and homogeneous presence of catalyst in the macro-pores of the filter walls and a suitably low soot load are needed. Under optimal soot-catalyst contact conditions, the consequent decrease in the temperature required for soot oxidation to values within the temperature range of diesel exhausts suggests the passage to a continuous functioning mode for catalytic filters with simultaneous filtration and regeneration, thus overcoming the drawbacks of periodic regeneration performed in current applications.

Organic‐lean and organic‐rich size‐selected soot particles were exposed to a varying O3 concentration, progressively decreasing the soot‐water contact angle (θ) to study its impact on ice nucleation (IN). The IN ability of fresh and O3‐aged soot between 218 and 233 K was observed while monitoring the particle mass and size distributions. The properties of fresh and O3‐aged bulk organic‐lean soot samples with a low and high O3‐adsorption were characterized for soot‐water θ, chemical composition, functional groups, soot‐water interaction ability and porosity. By retaining the soot porosity between aged and unaged samples, we demonstrate that a decrease in θ after O3‐aging enhances organic‐lean soot IN via pore condensation and freezing. Fresh organic‐rich soot exhibits suppressed homogeneous freezing, but after O3‐aging it freezes within uncertainty of the homogeneous freezing threshold of solution drops, because of increased hydrophilicity. Plain Language Summary This study investigates the ice formation ability of soot exposed to O3 in the temperature range <−40°C relevant to the cirrus cloud regime for the role of surface wettability in the ice formation ability of organic‐lean and ‐rich soot. O3‐aged organic‐lean soot is more effective at forming ice crystals than unaged soot, due to an increase in soot‐water interaction ability promoting capillary condensation of water into porous structures that subsequently freeze. As the chemical functional group abundance of the organic‐lean soot does not change after O3‐exposure, the increased soot‐water interaction ability for the soot is attributed to O3‐H2O binding rather than surface oxidation. However, both water sorption isotherms and pore size distribution derived from N2 sorption measurements confirm the O3‐adsorption does not change the porosity of organic‐lean soot. This highlights the sole importance of hydrophilicity in pore water condensation prior to soot ice nucleation. O3‐aged organic‐rich soot shows poor ice formation ability because of unavailability of porous structures to condense capillary water. This study implies that organic‐lean soot will have an enhanced ice formation ability in the upper troposphere if exposed to O3 concentrations similar to that simulated in this study. Key Points Higher O3‐concentration leads to a larger decease in water contact angle for organic‐lean soot without changing the soot porosity The decrease in soot‐water contact angle from O3‐aging produces an ice nucleation enhancement for organic‐lean soot via PCF at T < 233 K O3‐aged organic‐rich soot freezes homogeneously at bulk droplet conditions despite increased hydrophilicity due to unavailable pores

Ice accumulation causes various problems in our daily life for human society. The daunting challenges in ice prevention and removal call for novel efficient antiicing strategies. Recently, photothermal materials have gained attention for creating icephobic surfaces owing to their merits of energy conservation and environmental friendliness. However, it is always challenging to get an ideal photothermal material which is cheap, easily fabricating, and highly photothermally efficient. Here, we demonstrate a low-cost, high-efficiency superhydrophobic photothermal surface, uniquely based on inexpensive commonly seen candle soot. It consists of three components: candle soot, silica shell, and polydimethylsiloxane (PDMS) brushes. The candle soot provides hierarchical nano/microstructures and photothermal ability, the silica shell strengthens the hierarchical candle soot, and the grafted low-surface-energy PDMS brushes endow the surface with superhydrophobicity. Upon illumination under 1 sun, the surface temperature can increase by 53 °C, so that no ice can form at an environmental temperature as low as −50 °C and it can also rapidly melt the accumulated frost and ice in 300 s. The superhydrophobicity enables the melted water to slide away immediately, leaving a clean and dry surface. The surface can also self-clean, which further enhances its effectiveness by removing dust and other contaminants which absorb and scatter sunlight. In addition, after oxygen plasma treatment, the surface can restore superhydrophobicity with sunlight illumination. The presented icephobic surface shows great potential and broad impacts owing to its inexpensive component materials, simplicity, ecofriendliness, and high energy efficiency.

Atmospheric black carbon (BC) warms Earth's climate, and its reduction has been targeted for near-term climate change mitigation. Models that include forcing by BC assume internal mixing with non-BC aerosol components that enhance BC absorption, often by a factor of ∼2; such model estimates have yet to be clearly validated through atmospheric observations. Here, direct in situ measurements of BC absorption enhancements (E abs ) and mixing state are reported for two California regions. The observed E abs is small—6% on average at 532 nm—and increases weakly with photochemical aging. The E abs is less than predicted from observationally constrained theoretical calculations, suggesting that many climate models may overestimate warming by BC. These ambient observations stand in contrast to laboratory measurements that show substantial E abs for BC are possible.

Efficient catalysts for soot oxidation are critical for mitigating environmental pollution. In this study, CoMn 2 O 4 spinel catalysts were synthesised using reverse co-precipitation and co-precipitation methods to evaluate their performance in soot oxidation and kinetic behaviour. All samples exhibited a tetragonal phase (XRD) and spherical morphology with rough surfaces (SEM). Raman spectroscopy confirmed structural disorder and oxygen vacancies, while XPS analysis revealed the presence of low-valence Mn ions, facilitating oxygen vacancy formation critical for soot oxidation. Additionally, the co-existence of Co and Mn ions contributed to a synergistic effect, enhancing the catalytic properties of the spinel structure. The reverse co-precipitation method produced a catalyst with a higher concentration of oxygen vacancies and active oxygen species among the samples. This sample demonstrated superior catalytic performance, achieving a T 50% of 424 °C, low activation energy (153 kJ/mol) and pre-exponential factor (25 min − 1 ). Soot TPR analysis highlighted the role of catalyst reducibility, while thermogravimetric analysis revealed that activation energy and pre-exponential factors were influenced by surface composition. These findings provide valuable insights into the design of efficient catalysts for soot oxidation, emphasising the importance of synthesis methods and surface characteristics.

High quality personal exposure data is fundamental to understanding the health implications of household energy interventions, interpreting analyses across assigned study arms, and characterizing exposure-response relationships for household air pollution. This paper describes the exposure data collection for the Household Air Pollution Intervention Network (HAPIN), a multicountry randomized controlled trial of liquefied petroleum gas stoves and fuel among 3,200 households in India, Rwanda, Guatemala, and Peru. The primary objectives of the exposure assessment are to estimate the exposure contrast achieved following a clean fuel intervention and to provide data for analyses of exposure-response relationships across a range of personal exposures. Exposure measurements are being conducted over the 3-y time frame of the field study. We are measuring fine particulate matter [PM  in aerodynamic diameter ( )] with the Enhanced Children's MicroPEM™ (RTI International), carbon monoxide (CO) with the USB-EL-CO (Lascar Electronics), and black carbon with the OT21 transmissometer (Magee Scientific) in pregnant women, adult women, and children of age, primarily via multiple 24-h personal assessments (three, six, and three measurements, respectively) over the course of the 18-month follow-up period using lightweight monitors. For children we are using an indirect measurement approach, combining data from area monitors and locator devices worn by the child. For a subsample (up to 10%) of the study population, we are doubling the frequency of measurements in order to estimate the accuracy of subject-specific typical exposure estimates. In addition, we are conducting ambient air monitoring to help characterize potential contributions of exposure from background concentration. Stove use monitors (Geocene) are being used to assess compliance with the intervention, given that stove stacking (use of traditional stoves in addition to the intervention gas stove) may occur. The tools and approaches being used for HAPIN to estimate personal exposures build on previous efforts and take advantage of new technologies. In addition to providing key personal exposure data for this study, we hope the application and learnings from our exposure assessment will help inform future efforts to characterize exposure to household air pollution and for other contexts. https://doi.org/10.1289/EHP6422.

Accurate in vitro assessment of nanoparticle cytotoxicity requires a careful selection of the test systems. Due to high adsorption capacity and optical activity, engineered nanoparticles are highly potential in influencing classical cytotoxicity assays. Here, four common in vitro assays for oxidative stress, cell viability, cell death and inflammatory cytokine production (DCF, MTT, LDH and IL-8 ELISA) were assessed for validity using 24 well-characterized engineered nanoparticles. For all nanoparticles, the possible interference with the optical detection methods, the ability to convert the substrates, the influence on enzymatic activity and the potential to bind proinflammatory cytokines were analyzed in detail. Results varied considerably depending on the assay system used. All nanoparticles tested were found to interfere with the optical measurement at concentrations of 50 μg cm −2 and above when DCF, MTT and LDH assays were performed. Except for Carbon Black, particle interference could be prevented by altering assay protocols and lowering particle concentrations to 10 μg cm −2 . Carbon Black was also found to oxidize H 2 DCF-DA in a cell-free system, whereas only ZnO nanoparticles significantly decreased LDH activity. A dramatic loss of immunoreactive IL-8 was observed for only one of the three TiO 2 particle types tested. Our results demonstrate that engineered nanoparticles interfere with classic cytotoxicity assays in a highly concentration-, particle- and assay-specific manner. These findings strongly suggest that each in vitro test system has to be evaluated for each single nanoparticle type to accurately assess the nanoparticle toxicity.