The health effects of inhaled electronic cigarette (e-cigarette) flavoring compounds are largely unknown. Earlier reports of their chemical reactivity have been conflicting, with some claiming, for example, that the d...
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The health effects of inhaled electronic cigarette (e-cigarette) flavoring compounds are largely unknown. Earlier reports of their chemical reactivity have been conflicting, with some claiming, for example, that the degradation of flavoring chemicals in e-cigarettes to aldehydes is statistically insignificant. It is thus important to understand how these molecules react to afford enhanced aerosol products. The purpose of the current study was to investigate the origin of formaldehyde, acrolein, and acetaldehyde in e-cigarettes that contain the popular additive, triacetin (TA). By using C-13 labeling and a combination of H-1 NMR and C-13 NMR, we were able to identify that ester hydrolysis of TA occurs to form acetic acid (HOAc) during aerosolization. The released HOAc acts as a catalyst in the degradation of propylene glycol (PG) and glycerol (GLY), increasing the formation of formaldehyde hemiacetals, acrolein, and acetaldehyde. A solution of 10% TA in 1:1 PG/GLY e-liquid was aerosolized using two different e-cigarettes at two wattages. Each device exhibited a significant increase in aldehyde levels, of up to 185% compared to the aerosol from a 1:1 PG/GLY e-liquid. In addition, the GLY formaldehyde hemiacetal was more predominant within the presence of HOAc, indicating that GLY may be relatively more prone to degradation from protonation.
The treatment of aerosols, clouds, radiation, and precipitation in climate models, in addition to their interactions and as- sociated feedbacks, has long been one of the largest sources of uncertainty in predicting an...
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The treatment of aerosols, clouds, radiation, and precipitation in climate models, in addition to their interactions and as- sociated feedbacks, has long been one of the largest sources of uncertainty in predicting any potential future climate changes. Although many improvements have been made in CMIP5, aerosols, clouds, radiation, and their feedbacks are still a problem in climate models, as concluded in IPCC AR5 and published papers. Many studies have shown that modeled aerosols, clouds, radiation, and precipitation agree with observations within a certain range on a global scale; however, large biases occur at the regional scale. Characterizing the effects of aerosols and clouds on energy and the hydrological cycle and understanding the interactions among aerosols, clouds, radiation, and precipitation, are critical for weather forecasting and climate models. Significant improvements are needed, which require advanced observations and modeling at a range of spatial and temporal scales.
Brake cleaner liquid is commonly used for cleaning of engines and motor parts. The commercially available products usually contain mainly volatile organic compounds. As a consequence brake cleaner evaporates fast and ...
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Brake cleaner liquid is commonly used for cleaning of engines and motor parts. The commercially available products usually contain mainly volatile organic compounds. As a consequence brake cleaner evaporates fast and almost completely from the cleaned surface. This case report presents a fatal accidental inhalation of brake cleaner liquid aerosols due to the attempted cleaning of a boat engine. A 16 year old boy was found lifeless in the engine compartment of a boat engine. In close proximity to the body, the police found cleanings wipes soaked with brake cleaner as well as a pump spray bottle filled with brake cleaner. Essentially the autopsy revealed a cerebral oedema with encephalomalacia, no coagulated blood as well as increased blood and tissue fluid content of the lung. Toxicological analysis revealed brake cleaner fluid in the lung, gastric content and heart blood. (c) 2018 Elsevier B.V. All rights reserved.
Atmospheric deposition of iron (Fe) can limit primary productivity and carbon dioxide uptake in some marine ecosystems. Recent modeling studies suggest that biomass burning aerosols may contribute a significant amount...
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Atmospheric deposition of iron (Fe) can limit primary productivity and carbon dioxide uptake in some marine ecosystems. Recent modeling studies suggest that biomass burning aerosols may contribute a significant amount of soluble Fe to the surface ocean. Existing studies of burn-induced trace element mobilization have often collected both entrained soil particles along with material from biomass burning, making it difficult to determine the actual source of aerosolized trace metals. In order to better constrain the importance of biomass versus entrained soil as a source of trace metals in burn aerosols, small-scale burn experiments were conducted using soil-free foliage representative of a variety of fire-impacted ecosystems. The resulting burn aerosols were collected in two stages (PM > 2.5 μm and PM < 2.5 μm) on cellulose filters using a high-volume air sampler equipped with an all-Teflon impactor. Unburned foliage and burn aerosols were analyzed for Fe and other trace metals using inductively coupled plasma mass spectrometry (ICP-MS). Results of this analysis show that less than 2% of Fe in plant biomass is likely mobilized as atmospheric aerosols during biomass burning events. The results of this study and estimates of annual global wildfire area were used to estimate the impact of biomass burning aerosols on total atmospheric Fe flux to the ocean. I estimate that foliage-derived Fe contributes 114 ± 57 Gg annually. Prior studies, which implicitly include both biomass and soil-derived Fe, concluded that biomass burning contributes approximately 690 Gg of Fe. Together, these studies suggest that fire-entrained soil particles contribute 83% (576 Gg) of Fe in biomass burning emissions, while plant derived iron only accounts for at most 17%.
Pharmaceutical aerosols are used to treat many pulmonary diseases. The use of low-density powders has proven useful to support efficient drug delivery. Measurements must account for the low-density, spherical particle...
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Pharmaceutical aerosols are used to treat many pulmonary diseases. The use of low-density powders has proven useful to support efficient drug delivery. Measurements must account for the low-density, spherical particle features contributing to aerodynamic behavior. Ideally, the aerodynamic particle size distribution (APSD) is measured experimentally. Without formal measurement of APSD, calculations may be performed using surrogate measures such as bulk or tapped density and dynamic shape factor in Stokes' equation. However, the particles' low density must be established independently for this approach to be valid. In addition, where particles deviate from sphericity, the dynamic shape factor must be estimated from aerodynamic measurement not from geometric imaging of morphology. Finally, geometric sizing from particle images results in number distributions that exhibit smaller median sizes than mass distributions for the same polydisperse system. Simply applying density and shape factor corrections to geometric particle sizes does not convert number distributions to mass distributions. For log-normally distributed particle size distributions, Hatch-Choate equations, employing both median size and geometric standard deviation terms, may be used to convert number to mass distributions. Assigning small APSDs from calculations based on erroneous assumptions will result in serious interpretive flaws in subsequent in vitro and in vivo data. (c) 2018 American Pharmacists Association (R). Published by Elsevier Inc. All rights reserved.
Titan, Saturns largest moon, has a dense atmosphere, together with lakes and seas of liquid hydrocarbons. These liquid bodies, which are in polar regions and up to several hundred kilometres in diameter, generally hav...
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Volatile organic molecules formed by photochemistry in the upper atmosphere of Titan can undergo condensation as pure ices in the stratosphere and the troposphere as well as condense as ice layers onto the organic aer...
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We measured H-1 and C-13 nuclear magnetic resonance (NMR) spectra of Humic-like substances (HULIS) in urban atmospheric aerosols isolated by diethylaminoethyl (DEAE) and hydrophilic-lipophilic balance (HLB) resin to c...
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We measured H-1 and C-13 nuclear magnetic resonance (NMR) spectra of Humic-like substances (HULIS) in urban atmospheric aerosols isolated by diethylaminoethyl (DEAE) and hydrophilic-lipophilic balance (HLB) resin to characterize their chemical structure. HULIS isolated by DEAE resin were characterized by relatively high contents of aromatic protons and relatively low contents of aliphatic protons in comparison with HULIS isolated by HLB resin, while the contents of protons bound to oxygenated aliphatic carbon atoms were similar. These results were consistent with the results of the C-13 NMR analysis and indicate that hydrophobic components were more selectively adsorbed onto HLB, while DEAE resins selectively retained aromatic carboxylic acids. Furthermore, we demonstrated that the chemical structural features of HULIS were significantly different between spring and summer samples and that these disparities were reflective of their different sources. The estimated concentrations of HULIS in spring were found to be regulated by vehicle emissions and pollen dispersion, while the behavior of HULIS in summer was similar to photochemical oxidant and nitrogen dioxide concentrations. The proportion of aliphatic protons for summer samples was higher than that for spring samples, while the proportion of aromatic protons for summer samples was lower than that for spring samples. These seasonal changes of the chemical structure may also involve in their functional expression in the atmosphere.
The presence of small ions influences the growth dynamics of a size distribution of aerosols. Specifically the often neglected mass of small ions influences the aerosol growth rate, which may be important for terrestr...
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