Ozone (O3) pollution is becoming increasingly severe in China. In addition, our limited understanding of the relationship between O3 and volatile organic compounds (VOCs), is an obstacle to improving air quality. By developing an improved source-oriented speciated VOC emission inventory in 2013, we estimated the ozone formation potential (OFP) and investigated its characteristics in China. Besides, a comparison was made between our estimates and space-based observations from the ozone monitoring instrument (OMI) on the National Aeronautics and Space Administration (NASA)’s Aura satellite. According to our estimates, m-/p-xylene, ethylene, formaldehyde, toluene, and propene were the five species that had the largest potential to form ozone, and on-road vehicles, industrial processes, biofuel combustion, and surface coating were the key contributing sectors. Among different regions of China, the North China Plain, Yangtze River Delta, and Pearl River Delta had the highest OFP values. Our results suggest that O3formation is VOC-limited in major urban areas of China. Additionally, considering the different photochemical reactivities of various VOC species and the disparate energy and industry structures in the different regions of China, more efficient OFP-based and localized VOC control measures should be implemented, instead of the current mass-based and nationally uniform policies.
The distribution of archaeal community and the associated environmental variables in constructed wetland (CW), especially in free water surface flow CW (FWSF-CW), remain poorly understood. The present study explored the spatial and temporal dynamics of archaeal community in an FWSF-CWused for surface water treatment and evaluated the driving environmental variables. The archaeal density varied considerably among sites and seasons, ranging from 3.37 x 10(8) to 3.59 x 10(9) 16S rRNA gene copies per gram dry sediment/soil. The archaeal population density was adversely affected by high temperatures and tended to be lower during summer than during spring and winter. Moreover, considerable spatio-temporal variations of archaeal richness, diversity and community structure also occurred in the FWSF-CW. Higher nutrient contents correlated with a lower archaeal richness and diversity. Nitrate and carbon/nitrogen ratiowere found to play important roles in shaping the overall archaeal community structure. Euryarchaeota and Bathyarchaeota were the dominant archaeal phyla in wetland sediments, while Thaumarchaeota tended to be dominant in wetland soils. In addition, the wetland archaeal community was related to vegetation type. (C) 2017 Elsevier B.V. All rights reserved.
Biochars derived from animal manures may accumulate potentially toxic metals and cause a potential risk to ecosystem. The synchrotron-based X-ray spectroscopy, sequential fractionation schemes, bioaccessibility extraction and leaching procedure were performed on poultry and swine manure-derived biochars (denoted PB and SB, respectively) to evaluate the variance of speciation and activity of Cu and Zn as affected by the feedstock and pyrolysis temperature. The results showed that Cu speciation was dependent on the feedstock with Cu-citrate-like in swine manure and species resembling Cu-glutathione and CuO in poultry manure. Pyrolyzed products, however, had similar Cu speciation mainly with species resembling Cu-citrate, CuO and CuS/Cu2S. Organic bound Zn and Zn-3(PO4)(2)-like species were dominant in both feedstock and biochars. Both Cu and Zn leaching with synthetic precipitation leaching procedure (SPLP) and toxicity characteristic leaching procedure (TCLP) decreased greatly with the rise of pyrolysis temperature, which were consistent with the sequential extraction results that pyrolysis converted Cu and Zn into less labile phases such as organic/sulfide and residual fractions. The potential bioaccessibility of Zn decreased for both the PB and SB, closely depending on the content of non-residual Zn. The bioaccessibility of Cu, however, increased for the SB prepared at 300 degrees C-700 degrees C, probably due to the increased proportion of CuO. Concerning the results of sequential fractionation schemes, bioaccessibility extraction and leaching procedure, pyrolysis at 500 degrees C was suggested as means of reducing Cu/Zn lability and poultry manure was more suitable for pyrolysis treatment. (C) Higher Education Press and Springer-Verlag Berlin Heidelberg 2017
Salivary and pancreatic amylases (encoded by AMY1 and AMY2 genes, respectively) are responsible for digesting starchy foods. AMY1 and AMY2 show copy number variations that affect differences in amylase amount and activity, and AMY1 copies have been associated with adiposity. We investigated whether genetic variants determining amylase gene copies are associated with 2-year changes in adiposity among 692 overweight and obese individuals who were randomly assigned to diets varying in macronutrient content. We found that changes in body weight (BW) and waist circumference (WC) were significantly different according to the AMY1-AMY2 rs11185098 genotype. Individuals carrying the A allele (indicating higher amylase amount and activity) showed a greater reduction in BW and WC at 6, 12, 18, and 24 months than those without the A allele (P < 0.05 for all). The association was stronger for long-term changes compared with short-term changes of these outcomes. The genetic effects on these outcomes did not significantly differ across diet groups. In conclusion, the genetic variant determining starch metabolism influences the response to weight-loss dietary intervention. Overweight and obese individuals carrying the AMY1-AMY2 rs11185098 genotype associated with higher amylase activity may have greater loss of adiposity during low-calorie diet interventions.
Simultaneous measurements of meteorological data, trace gases, and volatile organic compounds were made in two regional sites, viz. Backgarden and Kaiping, in the Pearl River Delta (PRD) during summer and autumn, respectively. The strong deviations from the NO-NO2-O-3 Photostationary State, quantified by the leighton ratios, are carefully deduced through a comprehensive data set consist of the high-quality measurements of NO, NO2, O-3 and JNoz as well as the peroxy radical measurements. This is the first report of the Leighton ratio in China, with relatively high recorded values of 2.3 +/- 0.4 (Backgarden) and 3.1 +/- 1.4 (Kaiping), suggesting a strongly oxidising atmosphere in the PRD, typical of the ozone pollution season. A sensitivity analysis using a zero-dimensional chemical box model based on the regional atmospheric chemistry mechanism, version 2 (RACM2) constrained by the experimental measurements, indicated that peroxy radicals account for 70 (Backgarden) and 66% (Kaiping) of the observed positive deviations from the NOx photostationary state (characterized by a Leighton ratio of 1) on average. We consider that the remaining deviations result from neglecting the effects of chlorine chemistry, so We introduced a Cl chemistry module into RACM2, and the modelled results for Cl were as follows: 4.7 x 10(-4) pptv in Backgarden and 1.3 x 10(-3) pptv in Kaiping; these results are lower than the CI concentration derived from the NOx photostationary state. More work is required to confirm the role of additional peroxy radical sources at both high and low NOx regimes, as well as that of the halogen radicals, in perturbing the NO-NOx-O-3 cycle, which would significantly enhance trace gas removal and photochemical ozone production. (C) 2017 Elsevier Ltd. All rights reserved.
Objective: To investigate the clinical phenotypes and the mutant allele proportion of parents with SCN1A gene mutation mosaicism of Dravet syndrome (DS) children, thus to provide guidance for family reproduction and prenatal diagnosis. Method: The clinical data and peripheral blood DNA samples of DS patients with a SCN1A gene mutation proved by Sanger sequencing were collected prospectively from February 2005 to November 2016 in Department of Pediatrics, Peking University First Hospital. The same mutation was searched in parents and other available relatives. Parental somatic mosaicism was confirmed and quantified by Ion Torrent Personal Genome Machine (PGM) and Raindrop droplet digital PCR (ddPCR). The families were followed up and prenatal diagnosis was provided. Result: Mosaicisms of SCN1A gene mutation in parents were identified in 5.2% (30 out of 575) DS families. Seventeen were fathers and thirteen were mothers. The mutant allele proportion ranged from 1.7% to 32.9% by PGM and from 0.82% to 34.51% by ddPCR, respectively. In 30 parents with somatic mosaicism, thirteen were asymptomatic, ten had a history of febrile seizures (FS), five with epilepsy, one with febrile seizure plus and one had a history of afebrile seizure. Four families had two children with DS. Three siblings of the probands were confirmed genetically with the same pathogenic mutation. One deceased sister of the proband was assumed to have the same pathogenic mutation because she matched DS diagnosis after medical history review despite no blood sample. Two families received prenatal diagnosis. One second pregnancy was terminated because the fetus inherited the mutation as the mother's wish. Conclusion: Sanger sequencing detects parents of some children with DS are SCN1A mutation mosaics. PGM and ddPCR can be used for accurate quantification of mutant mosaics, which can provide accurate guidance for family genetic counseling.
The particle phase state is a key factor for determining gas particle partitioning, particle reactive gas uptake, and multiphase chemical reactions, with associated links to secondary aerosol formation. In this study, the particle phase state was investigated by measuring particle rebound fraction fin the highly polluted atmosphere of Beijing, China. The particle phase state was sensitive to ambient relative humidity (RH). The particles changed from rebounding to adhering when the RH increased above 60%, suggesting a transition from the semisolid to liquid state. This transition RH was below the deliquescence RH of both (NH4)(2)SO4 and NH4NO3. Submicrometer particles were in the liquid state during heavy haze episodes. This might be because the elevated RH and inorganic fraction in particles resulted in an increase in aerosol liquid water content. The transition to a liquid phase state, marking the beginning of the haze episode, might kick off a positive feedback loop. The liquid particles might readily take up pollutants that then react to form inorganics, thereby further increasing the rate of water uptake. We propose that the liquid phase state facilitates the mass transfer and multiphase reactions of the particles, thereby accelerating secondary particle growth in haze over the North China Plain.
The particle phase state is a key factor for determining gas particle partitioning, particle reactive gas uptake, and multiphase chemical reactions, with associated links to secondary aerosol formation. In this study, the particle phase state was investigated by measuring particle rebound fraction fin the highly polluted atmosphere of Beijing, China. The particle phase state was sensitive to ambient relative humidity (RH). The particles changed from rebounding to adhering when the RH increased above 60%, suggesting a transition from the semisolid to liquid state. This transition RH was below the deliquescence RH of both (NH4)(2)SO4 and NH4NO3. Submicrometer particles were in the liquid state during heavy haze episodes. This might be because the elevated RH and inorganic fraction in particles resulted in an increase in aerosol liquid water content. The transition to a liquid phase state, marking the beginning of the haze episode, might kick off a positive feedback loop. The liquid particles might readily take up pollutants that then react to form inorganics, thereby further increasing the rate of water uptake. We propose that the liquid phase state facilitates the mass transfer and multiphase reactions of the particles, thereby accelerating secondary particle growth in haze over the North China Plain.
The ultralow friction between atomic layers of hexagonal MoS2, an important solid lubricant and additive of lubricating oil, is thought to be responsible for its excellent lubricating performances. However, the quantitative frictional properties between MoS2 atomic layers have not been directly tested in experiments due to the lack of conventional tools to characterize the frictional properties between 2D atomic layers. Herein, a versatile method for studying the frictional properties between atomic-layered materials is developed by combining the in situ scanning electron microscope technique with a Si nanowire force sensor, and the friction tests on the sliding between atomic-layered materials down to monolayers are reported. The friction tests on the sliding between incommensurate MoS2 monolayers give a friction coefficient of ≈10−4 in the regime of superlubricity. The results provide the first direct experimental evidence for superlubricity between MoS2 atomic layers and open a new route to investigate frictional properties of broad 2D materials.
