Use of electronic cigarettes has grown exponentially over the past few years, raising concerns about harmful emissions. This study quantified potentially toxic compounds in the vapor and identified ...key parameters affecting emissions. Six principal constituents in three different refill “e-liquids” were propylene glycol (PG), glycerin, nicotine, ethanol, acetol, and propylene oxide. The latter, with mass concentrations of 0.4–0.6%, is a possible carcinogen and respiratory irritant. Aerosols generated with vaporizers contained up to 31 compounds, including nicotine, nicotyrine, formaldehyde, acetaldehyde, glycidol, acrolein, acetol, and diacetyl. Glycidol is a probable carcinogen not previously identified in the vapor, and acrolein is a powerful irritant. Emission rates ranged from tens to thousands of nanograms of toxicants per milligram of e-liquid vaporized, and they were significantly higher for a single-coil vs a double-coil vaporizer (by up to an order of magnitude for aldehydes). By increasing the voltage applied to a single-coil device from 3.3 to 4.8 V, the mass of e-liquid consumed doubled from 3.7 to 7.5 mg puff–1 and the total aldehyde emission rates tripled from 53 to 165 μg puff–1, with acrolein rates growing by a factor of 10. Aldehyde emissions increased by more than 60% after the device was reused several times, likely due to the buildup of polymerization byproducts that degraded upon heating. These findings suggest that thermal degradation byproducts are formed during vapor generation. Glycidol and acrolein were primarily produced by glycerin degradation. Acetol and 2-propen-1-ol were produced mostly from PG, while other compounds (e.g., formaldehyde) originated from both. Because emissions originate from reaction of the most common e-liquid constituents (solvents), harmful emissions are expected to be ubiquitous when e-cigarette vapor is present.
This study characterized emissions from IQOS, a heated tobacco product promoted as a less harmful alternative to cigarettes. Consumable tobacco plugs were analyzed by headspace GC/MS to assess the ...influence of heating temperature on the emission profile. Yields of major chemical constituents increased from 4.1 mg per unit at 180 °C to 6.2 mg at 200 °C, and 10.5 mg at 220 °C. The Health Canada Intense smoking regime was used to operate IQOS in an environmental chamber, quantifying 33 volatile organic compounds in mainstream and sidestream emissions. Aldehydes, nitrogenated species, and aromatic species were found, along with other harmful and potentially harmful compounds. Compared with combustion cigarettes, IQOS yields were in most cases 1–2 orders of magnitude lower. However, yields were closer to, and sometimes higher than electronic cigarettes. Predicted users’ daily average intake of benzene, formaldehyde, acetaldehyde and acrolein were 39 μg, 32 μg, 2.2 mg and 71 μg, respectively. Indoor air concentrations were estimated for commonly encountered scenarios, with acrolein levels of concern (over 0.35 μg m–3) derived from IQOS used in homes and public spaces. Heated tobacco products are a weaker indoor pollution source than conventional cigarettes, but their impacts are neither negligible nor yet fully understood.
We analyze the modifications that a dense nuclear medium induces in the Ds0⁎(2317)± and Ds1(2460)±. In the vacuum, we consider them as isoscalar D(⁎)K and ▪S-wave bound states, which are dynamically ...generated from effective interactions that lead to different Weinberg compositeness scenarios. Matter effects are incorporated through the two-meson loop functions, taking into account the self energies that the D(⁎), ▪, K, and ▪ develop when embedded in a nuclear medium. Although particle-antiparticle Ds0,s1(⁎)(2317,2460)+versusDs0,s1(⁎)(2317,2460)− lineshapes are the same in vacuum, we find extremely different density patterns in matter. This charge-conjugation asymmetry mainly stems from the very different kaon and antikaon interaction with the nucleons of the dense medium. We show that the in-medium lineshapes found for these resonances strongly depend on their D(⁎)K/▪ molecular content, and discuss how this novel feature can be used to better determine/constrain the inner structure of these exotic states.
Reactive Black 5, RB5, has been used as a model azo dye to evaluate the removal efficiency of sorption on Macrocystis pyrifera biomass (Mpyr) and commercial zerovalent iron nanoparticles (nZVI) in ...individual and combined treatments. The best conditions for the treatment with the isolated materials were first determined, and then, in series and combined treatments were performed under these conditions, achieving removal efficiencies higher than 80% of the initial dye concentration. Strengths and weaknesses of all removal strategies (individual, in series and combined) are analyzed regarding the application on real effluents. Mpyr efficiently adsorbed RB5, but also increased the total organic content by partial dissolution of components of the algal biomass. Removal experiments with commercial nZVI were also efficient but liberated Fe to the solution, and sulfanilic acid was observed after the treatment as a product of RB5 degradation. In contrast, after the Mpyr treatment, no sulfanilic acid was detected, suggesting that sulfanilic acid is efficiently adsorbed by the biomass. The best condition was the integrated use of Mpyr and nZVI, with a remarkable removal efficiency (69–80%) obtained after only 1 h of treatment. Finally, nZVI were successfully immobilized in Mpyr, and the hybrid material was used to remove RB5 in continuous flow experiments at pH 3, obtaining a removal capacity of 39.9 mg RB5 g−1 after a total processed volume of 630 mL of RB50 = 100 mg L−1.
•RB5 removal with zerovalent iron nanoparticles and Macrocystis pyrifera biomass.•Integrated use of Mpyr and N25 yielded remarkable removal efficiency (69–80%).•nZVI immobilized in Mpyr yielded a removal capacity of 71.5 mg RB5 g−1 nZVI@Mpyr.
Self-cleaning surfaces containing TiO2 nanoparticles have been postulated to efficiently remove NOx from the atmosphere. However, UV irradiation of NOx adsorbed on TiO2 also was shown to form harmful ...gas-phase byproducts such as HONO and N2O that may limit their depolluting potential. Ambient pressure XPS was used to study surface and gas-phase species formed during adsorption of NO2 on TiO2 and subsequent UV irradiation at λ = 365 nm. It is shown here that NO3(-), adsorbed on TiO2 as a byproduct of NO2 disproportionation, was quantitatively converted to surface NO2 and other reduced nitrogenated species under UV irradiation in the absence of moisture. When water vapor was present, a faster NO3(-) conversion occurred, leading to a net loss of surface-bound nitrogenated species. Strongly adsorbed NO3(-) in the vicinity of coadsorbed K(+) cations was stable under UV light, leading to an efficient capture of nitrogenated compounds.
•An outstanding Cr(VI) removal was achieved with these nZVI in only 30min.•The passive outer layer formed after treatment prevents further Cr(VI) removal.•Cr(III) is the only chromium species at the ...external layer after reaction.•A structure of hydroxychromites→magnetite→Fe0 developed towards the core of the nZVI.
Nanoscale zerovalent iron (nZVI) particles were successfully employed for Cr(VI) removal from aqueous solutions at pH 3. It was found that the capacity of the system increases with increasing nZVI dosage. Starting at 300μM, a complete Cr(VI) conversion was achieved in 30min with a Fe:Cr(VI) molar ratio (MR) of 3, and 45% conversion with MR=1 over the same period of time. The material exhibited an enhanced reactivity in comparison with other previously tested similar materials.
The proposed mechanism involves an initial reduction of Cr(VI) to Cr(III) by reaction with Fe0 or Fe(II) on the particle surface or in solution (secondary pathway), followed by an arrest on Cr(VI) removal attributed to the passivation of the surface of the nanoparticles. Passivation was confirmed by Raman and X-ray photoelectron spectroscopies (XPS). Furthermore, XPS analysis demonstrated that Cr(III) is the only Cr species present in the external layer of the nanoparticles after the reaction. Raman analysis and XPS measurements performed after mild sputtering showed that nZVI exposed to Cr(VI) presented a structure, from outside to inside, of hydroxychromites→magnetite→Fe0.
E-cigarettes likely represent a lower risk to health than traditional combustion cigarettes, but they are not innocuous. Recently reported emission rates of potentially harmful compounds were used to ...assess intake and predict health impacts for vapers and bystanders exposed passively. Vapers’ toxicant intake was calculated for scenarios in which different e-liquids were used with various vaporizers, battery power settings and vaping regimes. For a high rate of 250 puff day–1 using a typical vaping regime and popular tank devices with battery voltages from 3.8 to 4.8 V, users were predicted to inhale formaldehyde (up to 49 mg day–1), acrolein (up to 10 mg day–1) and diacetyl (up to 0.5 mg day–1), at levels that exceeded U.S. occupational limits. Formaldehyde intake from 100 daily puffs was higher than the amount inhaled by a smoker consuming 10 conventional cigarettes per day. Secondhand exposures were predicted for two typical indoor scenarios: a home and a bar. Contributions from vaping to air pollutant concentrations in the home did not exceed the California OEHHA 8-h reference exposure levels (RELs), except when a high emitting device was used at 4.8 V. In that extreme scenario, the contributions from vaping amounted to as much as 12 μg m–3 formaldehyde and 2.6 μg m–3 acrolein. Pollutant concentrations in bars were modeled using indoor volumes, air exchange rates and the number of hourly users reported in the literature for U.S. bars in which smoking was allowed. Predicted contributions to indoor air levels were higher than those in the residential scenario. Formaldehyde (on average 135 μg m–3) and acrolein (28 μg m–3) exceeded the acute 1-h exposure REL for the highest emitting vaporizer/voltage combination. Predictions for these compounds also exceeded the 8-h REL in several bars when less intense vaping conditions were considered. Benzene concentrations in a few bars approached the 8-h REL, and diacetyl levels were close to the lower limit for occupational exposures. The integrated health damage from passive vaping was derived by computing disability-adjusted life years (DALYs) lost due to exposure to secondhand vapor. Acrolein was the dominant contributor to the aggregate harm. DALYs for the various device/voltage combinations were lower thanor comparable tothose estimated for exposures to secondhand and thirdhand tobacco smoke.
OBJECTIVE: To compare the diagnostic characteristics of tests used for a prompt diagnosis of chronic osteomyelitis in the diabetic foot, using bone histology as the criterion standard. The tests ...assessed were probe-to-bone (PTB), clinical signs of infection, radiography signs of osteomyelitis, and ulcer specimen culture. RESEARCH DESIGN AND METHODS: A prospective study was performed on patients with foot ulcers referred to our diabetic foot clinic. Ulcer infection was diagnosed by recording clinical signs of infection and taking specimens for culture. The presumptive diagnosis of osteomyelitis was based on these results and the findings of a plain X-ray and PTB test. All patients with a clinical suspicion of bone infection were subjected to surgical treatment of the affected bone. During surgery, bone specimens were obtained for a histological diagnosis of osteomyelitis. RESULTS: Over 2.5 years, 210 foot lesions were consecutively examined and 132 of these wounds with clinical suspicion of infection selected as the study sample. Of these, 105 (79.5%) lesions were diagnosed as osteomyelitis. Among the tests compared, the best results were yielded by the PTB test including an efficiency of 94%, sensitivity of 98%, specificity of 78%, positive predictive value of 95%, and negative predictive value of 91% (P < 0.001, κ 0.803); the positive likelihood ratio was 4.41, and the negative likelihood ratio was 0.02 (95% CI). CONCLUSIONS: In our outpatient population with a high prevalence of osteomyelitis, the PTB test was of greatest diagnostic value, especially for neuropathic ulcers, and proved to be efficient for detecting osteomyelitis in the diabetic foot.
Aims
To analyse the risk of reulceration caused by the transfer of lesions in patients with diabetes, undergoing resection of at least one metatarsal head.
Methods
A total of 119 patients with ...diabetes from the Diabetic Foot Unit (Complutense University, Madrid, Spain), who underwent resection of at least one metatarsal head were analysed prospectively from November 2006 to December 2011 to assess reulceration in the other metatarsal head.
Results
Seven patients were excluded for being subjected to a pan‐metatarsal head resection and 11 patients dropped out. During a median follow‐up period of 13.1 months (interquartile range 6.1–22.8 months), 41% of patients suffered from reulcerations. Reulceration frequency in patients operated on the 1st, 2nd, 3rd, 4th, 5th and several metatarsal heads was 9 (69%), 8 (44%), 12 (52%), 2 (25%), 6 (19%) and 4 (50%) events, respectively. The Cox regression model showed hazard ratios that were significant for the location of the metatarsal resection. The first metatarsal showed the highest risk for reulceration (hazard ratio 3.307; 1.472–7.430) and the fifth metatarsal showed the lowest risk (hazard ratio 0.339; 0.138–0.832).
Conclusions
Reulceration is a frequent event following resection of a metatarsal head and should be regarded as an implicit complication of the intervention. The location of the resection determines the risk of reulceration, which is highest for patients operated on the first metatarsal head and lowest for patients operated on the fifth metatarsal head.
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