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Considering a spherical misfitting precipitate growing into a finite elastic-perfectly plastic supersaturated matrix, a kinetic modeling for such solid-state partitioning phase transformation is presented, where the interactions of interface migration, solute diffusion and misfit accommodation are analyzed. The linkage between interface migration and solute diffusion proceeds through interfacial composition and interface velocity; their effects on misfit accommodation are mainly manifested in an effective transformation strain, which depends on instantaneous composition field and precipitate size. Taking γ to α transformation of a binary Fe-0.5 at.% C alloy under both isothermal and continuous cooling conditions as examples, the effects of misfit accommodation on the coupling interface migration and solute diffusion are well evaluated and discussed. For the isothermal transformation, a counterbalancing influence between mechanical and chemical driving forces is found so that the mixed-mode transformation kinetics is not sensitive with respect to the elastic–plastic accommodation of the effective misfit strain. Different from the isothermal process, during the continuous cooling condition, the effects of misfit accommodation on the kinetics of solid-state partitioning phase transformation are mainly manifested in the great decrease of the transformation starting temperature and the thermodynamic equilibrium composition. The present kinetic modeling was applied to predict the experimentally measured γ / α transformation of Fe-0.47 at.% C alloy conducted with a cooling rate of 10 K min −1 and a good agreement was achieved. [ABSTRACT FROM AUTHOR]

Abstract: Black carbon (BC), carbon monoxide (CO), and particle number size distribution were measured near a major urban expressway of Beijing during summer and winter field campaigns in 2009. BC was also observed at urban and rural sites. The temporal variations of BC and its relationships with CO and particle number size distribution were analyzed. The average BC concentrations at the roadside site were 12.3 and 17.9 μg m−3 during the summer and winter campaigns, respectively. BC concentrations ranked in the order of roadside > urban > rural. A general diurnal pattern at all sites showed that the higher BC levels were observed at night. The diurnal pattern of summertime BC at the roadside site followed the variations of heavy-duty diesel vehicles (HDDVs). The increased proportion of HDDVs at night contributed to high ΔBC/ΔCO ratios. This study suggests that HDDVs are an important contributor to nighttime BC and particle number concentrations of both Aitken and accumulation modes near major roadways in Beijing, especially in summer. [Copyright &y& Elsevier]

Size-resolved particulate matter in the three size ranges (0.2–0.5 μm, 0.5–1.0 μm, and 1.0–2.5 μm) were collected at a roadside site in Beijing during and after the 2008 Olympic Games. The concentrations of PM mass, 14 elements, 3 major inorganic ions, and carbonaceous species were determined. The main contributors to PM2.5 were crustal sources, vehicle emissions, secondary aerosol formation along with coal combustion, biomass from burning, and industrial processes, with vehicle emissions contributing more to roadside PM2.5 than in the urban areas. The peaks at 0.5–1.0 μm in summer for PM mass and inorganic ions were most likely due to secondary aerosol formation, whereas the peaks at 0.2–0.5 μm in winter for PM mass and some elements were probably attributed to combustion from heating sources. The temporary control measures applied during the Olympics showed different effects on various emission sources and chemical species. [Copyright &y& Elsevier]

• This study is the first to investigate indoor formaldehyde contribution to ambient. • Residential building materials are a significant source of ambient formaldehyde. • The share of residential emissions to 81 anthropogenic sources was 6.66% (rank 6th). • Residential emission intensities were higher in more urbanized areas. • Building density, building materials, T and RH are influencing factors of emission. This study investigates the contribution of formaldehyde from residential building materials to ambient air in mainland China. Based on 265 indoor field tests in 9 provinces, we estimate that indoor residential sources are responsible for 6.66% of the total anthropogenic formaldehyde in China's ambient air (range for 31 provinces: 1.88–18.79%). Residential building materials rank 6th among 81 anthropogenic sources (range: 2nd–10th for 31 provinces). Emission intensities show large spatial variability between and within regions due to different residential densities, emission characteristics of building materials, and indoor thermal conditions. Our findings indicate that formaldehyde from the indoor environment is a significant source of ambient formaldehyde, especially in urban areas. This study will help to more accurately evaluate exposure to ambient formaldehyde and its related pollutants, and will assist in formulating policies to protect air quality and public health. [ABSTRACT FROM AUTHOR]

Abstract Emissions from power plants in China and India contain a myriad of fine particulate matter (PM 2.5 , PM ≤ 2.5 μm in diameter) precursors, posing significant health risks among large, densely settled populations. Studies isolating the contributions of various source classes and geographic regions are limited in China and India, but such information could be helpful for policy makers attempting to identify efficient mitigation strategies. We quantified the impact of power generation emissions on annual mean PM 2.5 concentrations using the state-of-the-art atmospheric chemistry model WRF-Chem (Weather Research Forecasting model coupled with Chemistry) in China and India. Evaluations using nationwide surface measurements show the model performs reasonably well. We calculated province-specific annual changes in mortality and life expectancy due to power generation emissions generated PM 2.5 using the Integrated Exposure Response (IER) model, recently updated IER parameters from Global Burden of Disease (GBD) 2015, population data, and the World Health Organization (WHO) life tables for China and India. We estimate that 15 million (95% Confidence Interval (CI): 10 to 21 million) years of life lost can be avoided in China each year and 11 million (95% CI: 7 to 15 million) in India by eliminating power generation emissions. Priorities in upgrading existing power generating technologies should be given to Shandong, Henan, and Sichuan provinces in China, and Uttar Pradesh state in India due to their dominant contributions to the current health risks. Highlights • Health risks of emissions from power plants in China and India are estimated using the state-of-the-science framework. • Both mortality burdens and years of life lost (YLL) are calculated for each province/state in China and India. [ABSTRACT FROM AUTHOR]

Speciated mercury gridded emissions inventories together with chemical transport models and concentration measurements are essential when investigating both the effectiveness of mitigation measures and the mercury cycle in the environment. Since different mercury species have contrasting behaviour in the atmosphere, their proportion in anthropogenic emissions could determine the spatial impacts. In this study, the time series from 1970 to 2012 of the EDGARv4.tox2 global mercury emissions inventory are described; the total global mercury emission in 2010 is 1772 tonnes. Global grid-maps with geospatial distribution of mercury emissions at a 0.1° × 0.1° resolution are provided for each year. Compared to the previous tox1 version, tox2 provides updates for more recent years and improved emissions in particular for agricultural waste burning, power generation and artisanal and small-scale gold mining (ASGM) sectors. We have also developed three retrospective emissions scenarios based on different hypotheses related to the proportion of mercury species in the total mercury emissions for each activity sector; improvements in emissions speciation are seen when using information primarily from field measurements. We evaluated them using the GEOS-Chem 3-D mercury model in order to explore the influence of speciation shifts, to reactive mercury forms in particular, on regional wet deposition patterns. The reference scenario S1 (EDGARv4.tox2_S1) uses speciation factors from the Arctic Monitoring and Assessment Programme (AMAP); scenario S2 (“EPA_power”) uses factors from EPA's Information Collection Request (ICR); and scenario S3 (“Asia_filedM”) factors from recent scientific publications. In the reference scenario, the sum of reactive mercury emissions (Hg-P and Hg 2+ ) accounted for 25.3% of the total global emissions; the regions/countries that have shares of reactive mercury emissions higher than 6% in total global reactive mercury are China+ (30.9%), India+ (12.5%) and the United States (9.9%). In 2010, the variations of reactive mercury emissions amongst the different scenarios are in the range of −19.3 t/yr (China+) to 4.4 t/yr (OECD_Europe). However, at the sector level, the variation could be different, e.g., for the iron and steel industry in China reaches 15.4 t/yr. Model evaluation at the global level shows a variation of approximately ±10% in wet deposition for the three emissions scenarios. An evaluation of the impact of mercury speciation within nested grid sensitivity simulations is performed for the United States and modelled wet deposition fluxes are compared with measurements. These studies show that using the S2 and S3 emissions of reactive mercury, can improve wet deposition estimates near sources. [ABSTRACT FROM AUTHOR]

This study aims to clarify the formation of heterogeneous microstructure and its effect on corrosion properties of high-silicon stainless steel (high-Si SS) S38815 weldment. A series of tests about microstructure and electrochemical characteristics were performed, including the electron backscatter diffraction (EBSD) analysis, Mott-Schottky tests, electrochemical impedance spectroscopy (EIS) tests, potentiodynamic and potentiostatic polarization tests. The formation mechanism of heterogeneous microstructure related to high-silicon and its correlation on corrosion was discussed extensively. The results show that the significantly deformed and recrystallised grains were observed at the low temperature heat affected zone (LT-HAZ) and high temperature heat affected zone (HT-HAZ) respectively. The metastable pitting and low impedance values were formed in the above region, despite their low donor density. The deterioration in corrosion resistance of S38815 weldment as a result of high-angle grain boundaries (HAGBs) and carbides is more pronounced than the beneficial impact of Cr and Si oxidation. This study provides valuable references to the manufacturing and enhancing the anti-corrosion properties of this high-Si SS. • The first study of S38815 high silicon stainless steel weldment. • Further oxidation of chromium and silicon was observed in the heat-affected zone. • Temperature and stress of welding promote metastable pitting and impedance drop. [ABSTRACT FROM AUTHOR]

Hydrogen can play a key role in facilitating the transition to a future deeply decarbonized energy system and can help accommodate higher penetrations of renewables in the power system. Arguments to justify this conclusion are supported by an analysis based on real-world data from China's Western Inner Mongolia (WIM). The economic feasibility and decarbonization potential of renewable-based hydrogen production are discussed through an integrated power-hydrogen-emission analytical framework. The framework combines a high-resolution wind resource analysis with hourly simulation for the operation of power systems and hydrogen production considering technical and economic specifications on selection of three different types of electrolyzers and two operating modes. The results indicate that using wind power to produce hydrogen could provide a cost-competitive alternative (<2 $kg−1) to WIM's current coal-dominated hydrogen manufacturing system, contributing at the same time to important reductions in wind curtailment and CO 2 emissions. The levelized cost for hydrogen production is projected to decrease in the coming decade consistent with increases in wind power capacity and decreases in capital costs for electrolyzers. Lessons learned from the study can be applied to other regions and countries to explore possibilities for larger scale economically justified and carbon saving hydrogen production with renewables. • Propose an integrated power-hydrogen-emission analytical framework for H2 production. • Conduct hourly system simulations with real data for Western Inner Mongolia China. • Alkaline and solid oxide electrolyzers are the most cost-effective options for 2020 and 2030. • Carbon-free H2 produced from wind power can be cost-competitive (0.5-2 $/kg). • An evidence of economic feasibility for renewable-based H2 production to other regions/countries. [ABSTRACT FROM AUTHOR]

To better understand the role of stationary sources during the evolution of haze, we investigated sulfate formation characteristics at different stages of four haze events in Beijing, China. The mass fraction of sulfate in PM 2.5 increased while that of nitrate declined slightly during the worsening process of most haze events, consistent with higher ratios of SO 4 2−/NO 3 − on haze days (0.50 on average) than those on clean days (0.32 on average). Further calculations indicated that sulfate had a higher mass growth rate than nitrate during the haze-worsening process, probably due to regional transport of sulfate from heavy industrial areas accompanied by increased sulfate secondary transformation during polluted periods. We quantitatively evaluated the contribution of the S(IV) + NO 2 reaction (pH-dependent) in sulfate formation during the haze evolution. The production rate (P S(IV)+NO2) of the S(IV) + NO 2 pathway ranged from 1.97 × 10−4 to 5.91 (mean: 0.39) μg·m−3·h−1. Its proportion to sulfate total heterogeneous production rate (P S(IV)+NO2 / P het) was generally correlated positively with PM 2.5 concentrations, indicating the relative importance of this pathway on haze days. Due to the mutual restriction between aerosol pH and aerosol liquid water content (ALWC) during haze evolution, the relative contribution of the S(IV) + NO 2 pathway to sulfate heterogeneous formation was generally limited to 40%. Unlabelled Image • Compositions of secondary inorganic aerosols collected during haze events in Beijing are analyzed. • Sulfate has a higher mass growth rate than nitrate during the haze-worsening process. • Rapid increase of sulfate is caused by regional-transport together with secondary transformation. • The relative contribution of the S(IV) + NO 2 pathway to sulfate heterogeneous formation is generally limited to 40%. [ABSTRACT FROM AUTHOR]

Reverse austenite transformation (RAT) is critical for designing advanced high-strength steels (AHSS), which, however, has not been sufficiently studied in nanostructured (NS) steels or Fe alloys, and hence not fully understood yet. Herein, the RAT (e.g. ferrite to austenite) kinetics in the NS Fe alloy upon continuous heating was experimentally and theoretically investigated, where, the ultrafine austenite characterized by a sluggish growth velocity and a high thermal stability, and additionally, an appreciable solute partitioning detected using atom probe microscopy, indicate the diffusion-controlled mechanism of RAT. The double-edged role of grain boundaries (GBs) in the NS alloy is elucidated, i.e. enhancing the diffusivity due to the type-A kinetics, and simultaneously, facilitating the formation of constrained diffusion field mainly due to the segmented effect of GB nucleation. On this basis, a modified diffusion model incorporating the effect of GBs is implemented to understand the GB-constrained austenite growth and the associated partitioning behavior, and further complemented with Cahn model, an austenite growth model is applied to predict the overall kinetics of RAT in the NS Fe alloy. It then follows that a strategy by combination of diffusion-controlled growth model and microstructure model could serve as a framework to predict the kinetics of RAT in the NS alloys. Regarding the RAT kinetics in the NS alloys, the present work uncovers the ‘GB-constrained’ mechanism, which is expected to offer the potential application for nanostructure manipulation in the development of AHSS. [ABSTRACT FROM AUTHOR]

How to describe the bainitic transformation (BT) has always been considered as a key problem in designing high strength low alloyed (HSLA) steels. Here, an analytical treatment was performed to evaluate quantitatively the growth retardation of BTs, by analysis of thermodynamic driving force Δ G and kinetic energy barrier Q , in combination with modeling transformed fraction by Ravi et al. [Acta Mater. 105 (2016) 155‒164]. Unified expressions for thermo-kinetic correlation and generalized stability (GS) were derived for BT with simultaneously decreased Δ G and increased Q. By fits of the current model to experimental results, the more enduring BT comes from the higher GS, corresponding to the more sustainable BT. Based on a proposed criterion of high Δ G -high GS, the present model can be adopted to design the BT, which will produce the bainitic microstructure with high strength and high plasticity, as evidenced by the current experiments. [Display omitted] [ABSTRACT FROM AUTHOR]

The profiles of particulate polycyclic aromatic hydrocarbons (PAHs) near a major road and relative major sources were determined based on five 1-week intensive field campaigns in 2008 and 2009, and the impacts of temporary control measures on roadside PAHs during the Beijing Olympics are discussed. The annual average concentration of PAHs in the non-Olympic period was 42.3±52.4ng/m3 and clear seasonal variation was present. Diesel vehicles, gasoline vehicles and coal combustion were identified as the three possible major sources of roadside PAHs using positive matrix factorization analysis. During the Olympics, the average total PAH concentration decreased to 4.8±2.7ng/m3, which was attributed primarily to the reduction of local emissions. Temporary traffic control measures significantly changed the diurnal pattern of particulate PAHs at the roadside site. Diesel vehicle contribution, in particular, decreased to a negligible fraction because heavy-duty diesel vehicles were strictly banned. [ABSTRACT FROM AUTHOR]

Secondary inorganic aerosols (SIA, including sulfate, nitrate, and ammonium) were found to be the most dominant aerosol components during haze period. Elucidating the driving factors during liquid-phase reaction formation process of SIA is a key step for understanding the origin of airborne particulate pollution. In this work, we used online instruments and collected hourly concentrations of ions, gases, meteorological parameters in a northern city of China. Source emissions were estimated by receptor model PMF/ME2 pulling run solution (Partial Target Transformation-PMF: PTT-PMF), and six sources were identified (dust, coal combustion, vehicle exhaust, secondary sulfate, secondary nitrate and biomass burning & SOC). pH values were calculated by ISORROPIA-II, with an average value of 4.68. The relationships between RH, pH, source behaviors and concentrations of SIA during different pollution episodes were discussed. Source emissions were found to influence pH and subsequently the SIA; high RH could result in high SIA because aerosol water content in atmosphere increases with RH, which is favorable for liquid-phase reactions. Finally, we employed statistical and machine learning (Random forest classification: RFC) methods to analysis importance of driving factors on SIA formation during different pollution episodes. Results showed precursors, wet conditions, atmospheric oxidation capacity and acidity favor formation of sulfate and nitrate at different pollution levels; changes of gaseous precursors, RH and temperature are more important to determine PM 2.5 pollution classification (clean, slightly polluted, moderately polluted, heavily polluted episodes). The findings of this work can provide useful information for better understanding formation mechanism of SIA, mitigating air pollution and improving human health. Image 1 • Precursors, wet condition and acidity are favorable for secondary ions formation. • Gases emitted by primary sources influence secondary ions at pollution episodes. • The sensitivity factors of NO 3 − and SO 4 2− are different as pollution aggravation. • Random forest classification can help to understand feature importance of factors. • Gaseous precursors (NO 2 and SO 2) get the highest values of feature importance. [ABSTRACT FROM AUTHOR]

• ICP-MS/MS O 2 mode was applied to eliminate interferences in determination of arsenic. • Ultrasonic extraction with ultrapure water ensured the stability of arsenic species. • Most wild edible mushrooms tested contained only non-toxic organic arsenic species. • Inorganic arsenic in some tested mushrooms were relatively high. Some varieties of edible mushrooms can accumulate high contents of arsenic, which is a public health concern. In this study, we developed a high-performance liquid chromatography method linked to inductively coupled plasma triple quadrupole mass spectrometry (HPLC-ICP-MS/MS) for sensitive and accurate determination of arsenite, arsenate, monomethylarsonic acid, dimethylarsinic acid, arsenocholine and arsenobetaine in edible mushrooms. The six arsenic species were extracted ultrasonically from mushrooms using ultrapure water at 60 °C as the solvent, separated on a PRP-X100 anion exchange column (4.1 × 250 mm, 10 µm), with 20 mmol/L NH 4 HCO 3 and 50 mmol/L (NH 4) 2 CO 3 as the mobile phase, and quantified using ICP-MS/MS in the oxygen reaction mode. The linear range of the method was 0.5 µg/L–100 µg/L with detection and quantification limits of 2.5 µg/kg–10 µg/kg (S/N = 3), and 8 µg/kg–33 µg/kg (S/N = 10), respectively. This method was applied successfully to the detection and speciation of arsenic in eight varieties (266 samples) of mushrooms. Our results indicated that most wild edible mushrooms contained organic arsenic, mainly arsenobetaine and arsenocholine. However, the inorganic arsenic content of Armillariella tabescens (3.63 mg/kg) and parts of the cultivated Agaricus blazei murrill (up to 4.50 mg/kg) were relatively high, which is potential risk to the health of consumers. [ABSTRACT FROM AUTHOR]