Low SO2 Research Articles

Investigation of the SO2 release characteristics during co-combustion of Fenton/CaO treated municipal sewage sludge and rice husk

SO2 emissions from MSS combustion raise air purifying costs and environmental pollution. Molding pellets made from Fenton/CaO-conditioned MSS and rice husk (RH) were burned in a tube furnace. This research investigated the effects of RH/sludge mixing ratio, Fenton/CaO dosage, and burning temperature on SO2 release from molding fuel combustion. The synergistic effects of conditioning MSS and rice husk in combustion were fully analyzed. Optimal conditions for minimum SO2 had been obtained through Response surface methodology (RSM) analysis. Experiments indicated that RH lowered SO2 production, and MSS and RH had synergistic effects on SO2 release in combustion. The production of SO2 and the rate of fuel-S conversion both increased as combustion temperature rose. Increasing Fenton/CaO dosage could lower SO2 emissions and S conversion. RSM optimization outcomes were as follows: 67.9% RH, 165.1 mg/g Fenton/CaO conditioner, 801 °C combustion temperature, and the minimum SO2 output is 0.663 mg/g. These findings can advance SO2 control technology of MSS combustion.

Performance analysis of biomass gasification coupled with ultra-supercritical power generation system

In order to alleviate the impact of coal combustion on the environment, a scheme of biomass gasification in coal-fired ultra-supercritical power plant is proposed and simulated with Aspen plus. Simulation results show that the energy and exergy efficiencies of the coupled system have an increasing-decreasing tendency with the increase of the air/biomass ratio, reaching the maximum value when the air/biomass ratio is 1.6. The energy and exergy efficiencies of the coupled system decrease continuously with the increase of the excess air ratio. The coupled system has the highest energy and exergy efficiencies of 46.89% and 43.13%, which are 2.70% and 1.81% higher than those of an ultra-supercritical coal-fired system, respectively. Meanwhile, the coupled system has low CO2, SO2, and NOx emissions and thus many advantages in terms of environmental performance.

Variations in Sulfur and Nitrogen Oxidation Rates in Summer Aerosols from 2014 to 2020 in Wuhan, China

To date, research regarding the changes of the sulfur and nitrogen rates in Wuhan during the summer is limited. In this study, we analyzed the air quality in Wuhan, China, using water-soluble ion, gaseous precursor, and weather data. A Spearman correlation analysis was then performed to investigate the temporal changes in air quality characteristics and their driving factors to provide a reference for air pollution control in Wuhan. The results indicate that SO2 in the atmosphere at Wuhan undergoes secondary conversion and photo-oxidation, and the conversion degree of SO2 is higher than that of NO2. During the summers of 2016 and 2017, secondary inorganic atmospheric pollution was more severe than during other years. The fewest oxidation days occurred in summer 2020 (11 days), followed by the summers of 2017 and 2014 (25 and 27 days, respectively). During the study period, ion neutralization was the strongest in summer 2015 and the weakest in August 2020. The aerosols in Wuhan were mostly acidic and NH4+ was an important neutralizing component. The neutralization factors of all cations showed little change in 2015. K+, Mg2+, and Ca2+ level changes were the highest in 2017 and 2020. At low temperature, high humidity, and low wind speed conditions, SO2 and NO2 were more easily converted into SO42− and NO3−.

Targeting Atmospheric Oxidants Can Better Reduce Sulfate Aerosol in China: H2O2 Aqueous Oxidation Pathway Dominates Sulfate Formation in Haze.

Particulate sulfate is one of the most important components in the atmosphere. The observation of rapid sulfate aerosol production during haze events provoked scientific interest in the multiphase oxidation of SO2 in aqueous aerosol particles. Diverse oxidation pathways can be enhanced or suppressed under different aerosol acidity levels and high ionic strength conditions of atmospheric aerosol. The importance of ionic strength to sulfate multiphase chemistry has been verified under laboratory conditions, though studies in the actual atmosphere are still limited. By utilizing online observations and developing an improved solute strength-dependent chemical thermodynamics and kinetics model (EF-T&K model, EF is the enhancement factor that represents the effect of ionic strength on an aerosol aqueous-phase reaction), we provided quantitative evidence that the H2O2 pathway was enhanced nearly 100 times and dominated sulfate formation for entire years (66%) in Tianjin (a northern city in China). TMI (oxygen catalyzed by transition-metal ions) (14%) and NO2 (14%) pathways got the second-highest contributions. Machine learning supported the result that aerosol sulfate production was more affected by the H2O2 pathway. The collaborative effects of atmospheric oxidants and SO2 on sulfate aerosol production were further investigated using the improved EF-T&K model. Our findings highlight the effectiveness of adopting target oxidant control as a new direction for sustainable mitigation of sulfate, given the already low SO2 concentrations in China.

NO2 air pollution drives species composition, but tree traits drive species diversity of urban epiphytic lichen communities

Lichens serve as important bioindicators of air pollution in cities. Here, we studied the diversity of epiphytic lichens in the urban area of Munich, Bavaria, southern Germany, to determine which factors influence species composition and diversity. Lichen diversity was quantified in altogether 18 plots and within each, five deciduous trees were investigated belonging to on average three tree species (range 1–5). Of the 18 plots, two were sampled in control areas in remote areas of southern Germany. For each lichen species, frequency of occurrence was determined in 10 quadrats of 100 cm2 on the tree trunk. Moreover, the cover percentage of bryophytes was determined and used as a variable to represent potential biotic competition. We related our diversity data (species richness, Shannon index, evenness, abundance) to various environmental variables including tree traits, i.e. bark pH levels and species affiliation and air pollution data, i.e. NO2 and SO2 concentrations measured in the study plots. The SO2 levels measured in our study were generally very low, while NO2 levels were rather high in some plots. We found that the species composition of the epiphytic lichen communities was driven mainly by NO2 pollution levels and all of the most common species in our study were nitrophilous lichens. Low NO2 but high SO2 values were associated with high lichen evenness. Tree-level lichen diversity and abundance were mainly determined by tree traits, not air pollution. These results confirm that ongoing NO2 air pollution within cities is a major threat to lichen diversity, with non-nitrophilous lichens likely experiencing the greatest risk of local extinctions in urban areas in the future. Our study moreover highlights the importance of large urban green spaces for species diversity. City planners need to include large green spaces when designing urban areas, both to improve biodiversity and to promote human health and wellbeing.

Multiple pollutants control of NO, benzene and toluene from coal-fired plant by Mo/Ni impregnated TiO2-based NH3-SCR catalyst: A DFT supported experimental study

There was a dearth of understanding regarding the mechanism of MPC catalyst activity and the creation of effective MPC catalysts for industrial low oxygen and high SO2 concentration environments. Herein, Mo/Ni was utilized to modify the commonly used WVTiOX catalyst to investigate the role and reaction mechanism of Mo/Ni in the MPC process. Mo/Ni doping greatly improved the MPC performance of the WVTiOX catalyst, increased the number of Brønsted and Lewis acid sites on the surface, promoted surface active oxygen Oα ratio, and intensified metal oxide synergy. The TiO2 (001) models of WVTiOX and NiWVTiOX catalysts were built, and the adsorption energies of NH3, O2, NO, C6H6, and C7H8 gaseous molecules on the surfaces of the two catalysts were calculated by density functional theory (DFT). The DFT and in situ DRIFTS results proved that NH3-SCR process of the catalyst was mainly governed by the L-H mechanism, while the E-R mechanism also worked to a certain extent. The following are possible benzene and toluene oxidation pathways on NiWVTiOX: C6H6 → C6H4O2 → C4H2O3 → CO2 + H2O and C7H8 → C6H5CH2OH → C6H5CHO → C6H5COOH → C4H2O3 → CO2 + H2O.

Should India Move toward Vehicle Electrification? Assessing Life-Cycle Greenhouse Gas and Criteria Air Pollutant Emissions of Alternative and Conventional Fuel Vehicles in India.

We perform a state-specific life-cycle assessment of greenhouse gases (GHG) (CO2eq) and sulfur dioxide (SO2) emissions in India for representative passenger vehicles (two-wheelers, three-wheelers, four-wheelers, and buses) and technologies (internal combustion engine, battery electric, hybrid electric, and plug-in hybrid electric vehicles). We find that in most states, four-wheeler battery-electric vehicles (BEVs) have higher GHG and SO2 emissions than other conventional or alternative vehicles. Electrification of those vehicle classes under present conditions would not lead to emission reductions. Electrified buses and three-wheelers are the best strategies to reduce GHG emissions in many states, but they are also the worst strategy in terms of SO2 emissions. Electrified two-wheelers have lower SO2 emissions than gasoline in one state. The Indian grid would need to decrease its carbon dioxide emissions by 38-52% and SO2 emissions by 58-97% (depending on the state) for widespread vehicle electrification for sustainability purposes to make sense. If the 2030 goals for India under the Glasgow COP are met, we find that four-wheeler BEVs still have higher GHG emissions in 18 states compared to a conventional gasoline compact four wheeler, and all states will have higher SO2 emissions for BEVs across all vehicle types compared to their conventional counterparts.

Enhancement of desulfurization by hydroxyl ammonium ionic liquid supported on active carbon

Power plants emit sulfur dioxide (SO2) during combustion, which is typically removed via wet flue gas desulfurization, but this process produces numerous secondary pollutants. Ionic liquids (ILs) can potentially be used to remove SO2, but they suffer from poor mass transfer rates. Hydroxyl ammonium ILs are classical cheap ILs that contain electron-rich O and N sites that favor high absorption capacities. To accelerate mass transfer, two hydroxyl ammonium ILs, triethanolamine citrate and triethanolamine lactate, were immobilized on activated carbon (SILs) and used to capture SO2 from simulated flue gas. They exhibited excellent adsorption at low SO2 partial pressures due to the presence of a large gas-liquid interface. The molar adsorption ratios reached 7.65 and 2.40 mol/mol at 10 kPa SO2. The SILs possessed good SO2 selectivity in SO2/CO2 and SO2/O2 mixtures, because of the only 8% reduction in the total adsorption of SILs at 60 °C. And they exhibited excellent reversibility in which their total adsorption capacities were unaffected after 5 adsorption-desorption cycles. The mechanism analysis revealed that chemical adsorption was the major adsorption route, although physical adsorption also occurred. The main reactive sites included C–O and N–H groups in the ionic liquid. These SILs may potentially replace traditional chemical absorption materials for the separation of SO2 from flue gas.

Association between particulate matter, sulphur dioxide, nitrogen dioxide, ozone, benzo[a]pyrene air concentrations, suicide and suicide attempts in Poland

Background and objectivesCertain air pollutants are associated with mental health conditions, like cognitive decline, depression and suicide. The aim of the study was to assess the relationship between long-term exposure to airborne concentrations of particulate matter (PM), sulphur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3), benzo[a]pyrene (BaP) and suicide rates, suicide attempts and suicide attempts among people with mental disorder. MethodsThe data used covered the years 2013–2016 of 27 regions in Poland, came from the Chief Inspectorate for Environmental Protection, the Provincial Police Headquarters and the Central Statistical Office. Univariate and multivariate linear regression analyses had been performed. ResultsResults of the study indicate that ozone is correlated with the rate of suicide attempts, the rate of total suicides and attempts at suicide attempts among people with mental disorder (r = 0.548, p < 0.001; r = 0.371, p < 0.01; r = 0.422, p < 0.01, respectively). Independent predictors of suicide attempts were high ozone concentration (β = 0.00216, p < 0.001), high feminisation and a small number of beneficiaries of environmental social welfare per 10,000 population. Completed suicide rate was associated with increased air concentrations of PM10 particulate matter (b = 0.0003, p = 0.001; β = 0.003, p < 0.001), a high number of employees and a high level of total pollutant emissions (β = 0.00027, p = 0.031). Finally, suicide attempts among people with psychiatric disorder were linked to high ozone concentration (b = 0.0005; p < 0.001; β = 0.0003; p = 0.004) and low SO2 concentration (b = − 0.0011; p < 0.001; β = − 0.0008; p = 0.002). ConclusionsAir pollutions' impact on suicidality is comparable to some adverse demographic factors and it should be considered as a strong predictor for suicidal behaviour.

Greenwashing in the US metal industry? A novel approach combining SO2 concentrations from satellite data, a plant-level firm database and web text mining

This study deals with the issue of greenwashing, i.e. the false portrayal of companies as environmentally friendly. The analysis focuses on the US metal industry, which is a major emission source of sulfur dioxide (SO2), one of the most harmful air pollutants. One way to monitor the distribution of atmospheric SO2 concentrations is through satellite data from the Sentinel-5P programme, which represents a major advance due to its unprecedented spatial resolution. In this paper, Sentinel-5P remote sensing data was combined with a plant-level firm database to investigate the relationship between the US metal industry and SO2 concentrations using a spatial regression analysis. Additionally, this study considered web text data, classifying companies based on their websites in order to depict their self-portrayal on the topic of sustainability. In doing so, we investigated the topic of greenwashing, i.e. whether or not a positive self-portrayal regarding sustainability is related to lower local SO2 concentrations. Our results indicated a general, positive correlation between the number of employees in the metal industry and local SO2 concentrations. The web-based analysis showed that only 8% of companies in the metal industry could be classified as engaged in sustainability based on their websites. The regression analyses indicated that these self-reported ”sustainable” companies had a weaker effect on local SO2 concentrations compared to their “non-sustainable” counterparts, which we interpreted as an indication of the absence of general greenwashing in the US metal industry. However, the large share of firms without a website and lack of specificity of the text classification model were limitations to our methodology.

Using Bayesian networks for environmental health risk assessment.

The study investigated the potential relationships between air pollution, socio-economy, and proven pathologies (e.g., respiratory, cardiovascular) within an industrial area in Southern France (Etang de Berre), gathering steel industries, oil refineries, shipping, road traffic and experiencing a Mediterranean climate. A total of 178 variables were simultaneously integrated within a Bayesian model at intra-urban scale. Various unsupervised and supervised algorithms (maximum spanning tree, tree-augmented naive classifier) as well as sensitivity analyses were used to better understand the links between all variables, and highlighted correlations between population exposure to air pollutants and some pathologies. Adverse health effects (bronchus and lung cancers for 15-65 years old people) were observed for hydrofluoric acid at low background concentration (<0.003μgm-3) while exposure to particulate cadmium (0.210-0.250μgm-3) disrupts insulin metabolism for people over 65 years-old leading to diabetes. Bronchus and lung cancers for people over 65 years-old occurred at low background SO2 concentration (6μgm-3) below European limit values. When benzo[k]fluoranthene exceeded 0.672μgm-3, we observed a high number of hospital admissions for respiratory diseases for 15-65 years-old people. The study also revealed the important influence of socio-economy (e.g., single-parent family, people with no qualification at 15 years-old) on pathologies (e.g., cardiovascular diseases). Finally, a diffuse polychlorinated biphenyl (PCB) pollution was observed in the study area and can potentially cause lung cancers.

Study on Correlation Characteristics of PCDD/Fs Isomers Generation during the Coal-Combustion Process with Sludge Mixing

The 17 toxic polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) isomers as a persistent and refractory organic pollutant are one of the pollutants produced in solid fuel (including pulverized coal and mixed fuel) combustion, and regulating their distribution characteristics is an important aspect of effectively reducing their toxic equivalent. In this study, a correlation model of PCDD/Fs toxic equivalent was proposed to quantitatively analyze the correlation between HCl and SO2 concentrations in the reaction atmosphere, meanwhile, a pathway-diagnosis method of PCDD/Fs isomers transformation was adopted to analyze the PCDD/Fs distribution characteristics of coal combustion and that mixed with 10% sludge. The results show that the inflection point for the derivative of the relationship between HCl concentration and SO2 concentration moves towards the direction of lower SO2 concentration and higher HCl concentration with the increase of PCDD/Fs toxic equivalent. Besides, the functional pathways of mixing sludge on PCDD/Fs generation in coal combustion were obtained by calculating chlorine substitution probability. It has been deduced that five transformation pathways were improved by mixing sludge. Next, the critical pathways of the influence from mixing sludge on the distribution characteristics of PCDD/Fs isomers in coal combustion were analyzed by drawing the percentage content migration diagram of PCDD/Fs isomers and the average toxic equivalent migration diagram that combined with the toxic equivalent of PCDD/Fs isomers. The results showed that the main reasons for mixing sludge to further reduce the average toxic equivalent of PCDD/Fs isomers in coal combustion were the increased chlorine substitution probability at the 4-position of 12378 Pentachlorodibenzo-p-dioxin (12378-PeCDD), the decreased chlorine substitution probability at the 4-position of 2378 Tetrachlorodibenzo-p-furan (2378-TeCDF), and the increased total chlorine substitution probability of 23478 Pentachlorodibenzo-p-furan (23478-PeCDF), 123478-Hexachlorodibenzofuran (123478-HxCDF) and 123678-HxCDF respectively. Finally, the functional pathway diagram of PCDD/Fs isomers generated from coal combustion with sludge mixing was drawn.

Boosting low temperature De-NOx performance and SO2 resistance over Ce-doped two dimensional Mn-Cr layered double oxide catalyst

In this paper, Mn-Cr mixed oxides with different structures are prepared by a co-precipitation method and used as active catalysts for low-temperature NH3 selective catalytic reduction (SCR) of NO. The Mn-Cr layered structure catalyst shows the highest activity and SO2 resistance in SCR. Furthermore, a Ce doping process on the catalyst further improves the NH3-SCR activity with SO2 resistance. The features of unique texture property, acidity, reducibility, and Mn-Cr redox cycle in the derived Mn-Cr layered structure catalyst should contribute to the improved catalytic activity for the SCR. The SO2 resistance of the catalyst is also improved by suppressing manganese sulfate formation. The improved catalytic activity and SO2 resistance due to the reducibility and sulfur resistance of Ce suggest that the Ce-doped Mn-Cr layered structure catalyst could be used as an effective catalyst for NH3-SCR.

Promotion Effect of the Keggin Structure on the Sulfur and Water Resistance of Pt/CeTi Catalysts for CO Oxidation

Developing a catalyst with high SO2 and H2O resistance to achieve high-performance CO oxidation for specific industrial applications is highly desirable. Here, three catalysts were prepared using cerium titanium composite oxide (CeTi), molybdophosphate with Keggin structure-modified CeTi (Keg-CeTi), and molybdophosphate without Keggin structure-modified CeTi (MoP-CeTi) as supports, and their sulfur and water resistance in CO oxidation were tested. The characterization of XRD, BET, SO2/H2O-DRIFTS, XPS, TEM, SEM, NH3/SO2-TPD, H2-TPR, and ICP techniques revealed that the high SO2 and H2O resistance of Pt/Keg-CeTi in CO oxidation was related to its stronger surface acidity, better reduction of surface cerium and molybdenum species, and lower SO2 adsorption and transformation compared to Pt/CeTi and Pt/MoP-CeTi.

Simultaneous fractionation of sulfur dioxide explains mass independent fractionation of sulfur isotopes in Archean sedimentary pyrites

The relationship between ∆36S and ∆33S in Archean sedimentary pyrites has been used to evaluate early geologic processes, including photochemical reactions in the anoxic atmosphere, biological activity and thermochemical alteration during sediment deposition. We have applied statistical methods to quadruple S isotope analyses of Archean sedimentary pyrites, using data compiled from the literature. Most of the best-fit lines, on plots of ∆36S against ∆33S, have Archean reference array-like ∆36S/∆33S slopes that vary between −1.5 and − 0.9. Rigorous statistical tests were conducted to calculate the probability of the best-fit lines passing through the origin. Seventeen of 23 ∆36S-∆33S regression lines, which pass our reliability filter of R2 ≥ 75% and ∆33S range ≥ 2‰, have positive intercepts on the ∆36S axis, and 13 of these have a probability of < 5% of a zero intercept on the ∆36S axis. The observed ∆36S/∆33S slopes and the non-negative intercepts, which requires at least two mass-independent fractionation source reactions to operate simultaneously, can be produced by UV radiation in the atmosphere at low SO2 partial pressures by combining collision-induced intersystem crossing in the SO2 photoexcitation band (240–340 nm), with the self-shielding effect in the SO2 photolysis band (190–220 nm). The two SO2 photochemical processes must occur simultaneously in a single atmospheric reservoir in order that the fraction contributed by the end-member process remains constant across the full range of ∆33S values. We call this process simultaneous fractionation. We applied a two-end-member model to calculate the fraction of S contributed by the SO2 photoexcitation end-member (f) needed to produce the observed ∆36S/∆33S gradients and variable intercepts on the ∆36S axis in the Archean sedimentary pyrites, when the other end-member is SO2 photolysis with the self-shielding. The simplest explanation for variations in f, and therefore variations in ∆36S/∆36S gradients, is that it is controlled by changes in the partial pressure of SO2 in the atmosphere.

Valuation slagging factors and greenhouse gases emissions of paper mill reject and coal

There are quite a lot of paper mill rejects (PMR) as a by-product of paper mills and have not been utilized, currently. The purpose of this study is to evaluate the characteristics of paper mill reject (PMR) to coal and natural biomass and estimate the greenhouse (GHG) emissions of PMR and coal. Coal and PMR taken from five paper mills were analyzed for the content of moisture, proximate parameter (ash, volatile matter, fixed carbon), sulfur (S), gross calorific value (GCV), ash mineral and ash fusion temperature (AFT). The slagging factors of materials were calculated and evaluated. The resulting greenhouse gasses (GHG) emissions was also estimated. The results show that with the high calorific value, low ash and sulfur content of PMR, it has the potential to be used as a coal mixture for boiler fuel. It is very beneficial for the environment due to the low SO2 emissions. PMR has the characteristics of a low slagging index (SI), high fouling index (FI) and Slag Viscosity Index (SVI) which is almost similar with biomass, empty fruit bunches (EFB) and rice husk. The use of PMR as a coal mixture in paper mills in the amount of 10,285 ton/year can reduce greenhouse gases of 63.5 tons CO2-equivalent/year.

Wine Storage at Cellar vs. Room Conditions: Changes in the Aroma Composition of Riesling Wine.

Storage temperature is one of the most important factors affecting wine aging. Along with bottling parameters (type of stopper, SO2 level and dissolved O2 in wine), they determine how fast wine will evolve, reach its optimum and decline in sensory quality. At the same time, lowering of the SO2 level in wine has been a hot topic in recent years. In the current work, we investigated how Riesling wine evolved on the molecular level in warm (~25 °C) and cool (~15 °C) conditions depending on the SO2 level in the wine (low, medium and high), flushing of the bottle’s headspace with CO2 and three types of stoppers (Diam 30, Diam 30 origin and Diam 5) with different OIR levels (0.8–1.3 mg) and OTR levels (0.3–0.4 mg/year). It was demonstrated that the evolution of primary and secondary aromas, wine color and low molecular weight sulfur compounds (LMWSCs) during the two years of aging mainly depended on the storage temperature. Variation in the SO2 level and CO2 in the headspace affected mostly certain LMWSCs (H2S, MeSH) and β-damascenone. New aspects of C13-norisprenoids and monoterpenoids behavior in Riesling wine with different levels of SO2 and O2 were discussed. All three types of stoppers showed very close wine preservation properties during the two years of storage. The sensory analysis revealed that, after only six months, the warm stored wines with a low SO2 level were more oxidized and different from the samples with medium and high SO2 levels. A similar tendency was also observed for the cool stored samples.

Efficient absorption of low partial pressure SO2 by deep eutectic solvents based on pyridine derivatives

Efficient and reversible absorption of SO2 by deep eutectic solvents (DESs) has drawn much attention in recent years. In this work, a new type of deep eutectic solvents (DESs) were synthesized via pyridine derivatives, nicotinamide, aminopyridines and hydroxypyridines, as the hydrogen bond donors (HBDs) with common quaternary ammonium salt ionic liquids (ILs) as hydrogen bond acceptors (HBAs). The studied DESs exhibited an attractive absorption behavior for SO2, especially for low concentration SO2. The 1-allyl-3-methylimidazolium chloride (AmimCl)/2-aminopyridine (2-NH2Py) (2:1) and 1-butyl-3-methylimidazolium chloride (BmimCl)/3-aminopyridine (3-NH2Py) (2:1) could capture 0.273 and 0.223 g SO2/g DES at 293 K and 1.0 kPa, respectively, surpassing that of most DESs and ILs in the present literature. The influence of DES composition, temperature and pressure on SO2 absorption performance was systematically investigated. Moreover, the absorption mechanism studied by nuclear magnetic resonance (NMR) and Fourier transform infrared (FT-IR) spectroscopies indicated that the efficient absorption of SO2 was ascribed to the chemical interaction between the pyridine nitrogen atom and SO2.

Activity of keloids evaluated by multimodal photoacoustic/ultrasonic imaging system

Multiple objective assessments have been used to assess the activity of keloids to compare different therapeutic regimens and facilitate the best individual treatment choice for patients, but none of them are standardized. A multimodal photoacoustic/ultrasonic (PA/US) imaging system, including photoacoustic imaging, elastography, ultra-micro-angiography, and conventional US technologies (gray scale US, color Doppler US, and power Doppler US), was applied to evaluate keloids by a radiologist. Growing stages were defined by patients, and Vancouver Scar Scale (VSS) was assessed by a plastic surgeon. A comprehensive model based on multimodal ultrasound parameters (poor-echo pattern, high vascular density, decreased elasticity, and low SO2 within the keloid) and VSS might be a potential indicator of active keloids, comparing with VSS alone. The multimodal PA/US imaging system could be a promising technique for keloids assessment.

Synergistic effects of gaseous pollutants on hospital admissions for cardiovascular disease in Liuzhou, China.

Previous studies demonstrated that short-term exposure to gaseous pollutants (nitrogen dioxide (NO2), sulfur dioxide (SO2), and ozone (O3)) had a greater adverse effect on cardiovascular disease. However, little evidence exists regarding the synergy between gaseous pollutants and cardiovascular disease (CVD). Therefore, we aimed to estimate the effect of individual gaseous pollutants on hospital admissions for CVD and to explore the possible synergistic effects between gaseous pollutants. Daily hospitalization counts for CVD were collected from January 1, 2014, to December 31, 2015. We also collected daily time series on gaseous pollutants from the Environment of the People's Republic of China, including NO2, SO2, and O3. We used distributed lag nonlinear models (DLNMs) to assess the association of individual gaseous pollutants on CVD hospitalization, after controlling for seasonality, day of the week, public holidays, and weather variables. Then, we explored the variability across age and sex groups. In addition, we analyzed the synergistic effects between gaseous pollutants on CVD. Extremely low NO2 and SO2 increase the risk of CVD in all subgroup at lag 7 days. The greatest effect of high concentration of SO2 was observed in male and the elderly (≥ 65 years) at lag 3 days. Greater effects of high concentration of O3 were more pronounced in the young (< 65 years) and female at lag 3 days, while the effect of low concentration of O3 was greater in male and the young (< 65 years) at lag 0 day. We found a synergistic effect between NO2 and SO2 for CVD, as well as between SO2 and O3. The synergistic effects of NO2 and SO2 on CVD were stronger in the elderly (≥ 65) and female. The female was sensitive to synergistic effects of SO2-O3 and NO2-O3. Interestingly, we found that there was a risk of CVD in the susceptible population even for gaseous pollutant concentrations below the National Environmental Quality Standard. The synergy between NO2 and SO2 was significantly associated with cardiovascular disease hospitalization in the elderly (≥ 65). This study provides evidence for the synergistic effect of gaseous pollutants on hospital admissions for cardiovascular disease.