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Water-insoluble organic carbon (WIOC) constitutes a substantial portion of organic carbon (OC) and contributes significantly to light absorption by brown carbon (BrC), playing pivotal roles in climate forcing. China is a hotspot region with high levels of OC and BrC, but information regarding the sources and light-absorbing properties of WIOC on a national scale remains scarce. Here, we investigated the light-absorbing properties and sources of WIOC in 10 representative urban cities in China. On average, WIOC made up 33.4 ± 7.66 % and 40.5 ± 9.73 % of concentrations and light absorption at 365 nm (Abs 365) of extractable OC (EX-OC), which includes relatively hydrophobic OC (WIOC and humic-like substances, HULIS-C) and hydrophilic OC (non-humic-like substances, non-HULIS-C). The mass absorption efficiency of WIOC at 365 nm (MAE 365) was (1.59 ± 0.55 m2(gC)-1) comparable to that of HULIS (1.54 ± 0.57 m2(gC)-1) but significantly higher than non-HULIS (0.71 ± 0.28 m2(gC)-1), indicating that hydrophobic OC possesses a stronger light-absorbing capacity than hydrophilic OC. Biomass burning (31.0 %) and coal combustion (31.1 %) were the dominant sources of WIOC, with coal combustion sources exhibiting the strongest light-absorbing capacity. Moreover, employing the simple forcing efficiency (SFE 300–700nm) method, we observed that WIOC exhibited the highest SFE 300–700nm (6.57 ± 5.37 Wg-1) among the EX-OC fractions. The radiative forcing of EX-OC was predominantly contributed by hydrophobic OC (WIOC – 39.4 ± 15.5 % and HULIS – 39.5 ± 12.1 %). Considering the aromaticity, sources, and atmospheric processes of different carbonaceous components, we propose a light-absorbing carbonaceous continuum, revealing that components enriched with fossil sources tend to possess stronger light-absorbing capacity, higher aromatic levels, increased molecular weights, and greater recalcitrance in the atmosphere. Reducing fossil fuel emissions emerges as an effective means of mitigating both gaseous (CO2) and particulate light-absorbing carbonaceous warming components. [ABSTRACT FROM AUTHOR]

The optical properties of secondary brown carbon (BrC) aerosols are poorly understood, hampering quantitative assessments of their impact. We propose a new method for estimating secondary source of BrC using excitation‐emission matrix (EEM) fluorescence spectroscopy, combined with parallel factor analysis (PARAFAC) and partial least squares regression (PLSR). Experiments were conducted on a collection of PM2.5 samples from urban areas in five Chinese cities during winter and summer. The humic‐like component with long‐emission wavelengths (L‐HULIS) was identified as a secondary source tracer of BrC. This was confirmed by correlating PARAFAC components with secondary organic aerosol tracers and molecular oxidation indices obtained from Fourier transform ion cyclotron resonance mass spectrometry analysis. Using L‐HULIS as a secondary tracer of BrC, it was determined that the contribution of secondary sources to water‐soluble BrC (WS‐BrC) in source emission samples is significantly smaller than in PM2.5 from five Chinese cities, supporting our method. In the five cities, secondary source derived via L‐HULIS contributes a dominant potion (80% ± 3.5%) of WS‐BrC at 365 nm during the summer, which is approximately twice as high as during the winter (45% ± 4.9%). Radiocarbon isotope (14C) analysis provides additional constraints to the sources of L‐HULIS‐derived secondary WS‐BrC in urban PM2.5, suggesting that aged biomass burning is the dominant contributor to secondary WS‐BrC in winter, and biogenic emission is dominant during summer. This study is the first report on identification of secondary sources of BrC using the fluorescence technique. It demonstrates the potential of this method in characterizing non‐fossil source secondary BrC in the atmosphere. Plain Language Summary: Brown carbon (BrC) originates from primary combustion emissions and secondary formation, with large source‐dependent uncertainties of radiative forcing. Direct measurements to separate the primary and secondary BrC are challenging due to the chemical complexity. Recent online studies have shown that excitation‐emission matrix fluorescence spectroscopy coupled with parallel factor (PARAFAC) analysis identified some fluorescent components that may be linked to secondary sources. However, there is a knowledge gap on whether PARAFAC components correlate closely with atmospheric secondary chemical components, particularly biogenic and anthropogenic secondary organic aerosol, as their precursors can also form secondary BrC chromophores. We established the correlations between PARAFAC components and secondary organic aerosol tracers and compound oxidations to identify the long‐emission‐wavelength humic‐like component as a secondary source tracer of BrC. Then, we estimated non‐fossil source secondary BrC in urban aerosols during the winter and summer. Our studies provide references for quantifying secondary sources of BrC in the atmosphere. Key Points: A fluorescence‐based method was developed to investigate secondary sources of water‐soluble brown carbon in five cities in ChinaThe contribution of secondary sources to water‐soluble brown carbon in the summer is approximately twice as high as during the winterThis secondary water‐soluble brown carbon was more associated with aging biomass burning in winter and biogenic emissions in summer [ABSTRACT FROM AUTHOR]

Water-insoluble carbon (WIOC) constitutes a substantial portion of organic carbon (OC) and contributes significantly to light absorption by brown carbon (BrC), playing pivotal roles in climate forcing and human health. China as hotspots regions with high level of OC and BrC, information regarding the sources and light-absorbing properties of WIOC on national scale remains scarce. Here, we investigated the light-absorbing properties and sources of WIOC in ten representative urban cities across China. On average, WIOC accounted for 33.4 ± 7.66 % and 40.5 ± 9.73 % of the concentrations and light-absorbing efficiency at 365 nm (Abs365) of extractable OC (EX-OC, comprising relatively hydrophobic OC [WIOC and humic-like substances: HULIS-C], and hydrophilic OC [non-humic-like substances: non-HULIS-C]). The mass absorption efficiency of WIOC at 365 nm (MAE365) was (1.59 ± 0.55 m2/gC) comparable to that of HULIS (1.54 ± 0.57 m2/gC) but significantly higher than non-HULIS (0.71 ± 0.28 m2/gC), indicating that hydrophobic OC possesses a stronger light-absorbing capacity than hydrophilic OC. Biomass burning (31.0 %) and coal combustion (31.1 %) were the dominant sources of WIOC, with coal combustion sources exhibited the strongest light-absorbing capacity. Moreover, employing the simple forcing efficiency (SFE300–700nm) method, we observed that WIOC exhibited the highest SFE300–700nm (6.57 ± 5.37 W/g) among the EX-OC fractions. The radiative forcing of EX-OC was predominantly contributed by hydrophobic OC (WIOC: 39.4 ± 15.5 % and HULIS: 39.5 ± 12.1 %). Considering the aromaticity, sources, and atmospheric processes of different carbonaceous components, we propose a light-absorbing carbonaceous continuum, revealing that components enriched with fossil sources tend to possess stronger light-absorbing capacity, higher aromatic levels, increased molecular weights, and greater recalcitrance in the atmosphere. Reducing fossil fuel emissions emerges as an effective means of mitigating both gaseous (CO2) and particulate light-absorbing carbonaceous warming components. [ABSTRACT FROM AUTHOR]

Humic‐like substances (HULIS) are significant contributor to the light absorption of water‐soluble brown carbon (WSBrC), which contains certain strong light‐absorbing chemical components that are not well understood, impeding the assessment of WSBrC's climate impact. China as the hotspot regions with high loading of WSBrC characterized by high light‐absorbing capacity, here, we investigated the sources and atmospheric processes (δ13C–Δ14C), molecular composition (Fourier transform ion cyclotron resonance mass spectrometry), and light absorption properties (UV spectrophotometry) of HULIS in PM2.5 from 10 Chinese cities. HULIS‐C was major contributor to the light absorption coefficient (70.5 ± 6.6%) of WSBrC at 365 nm, which was more enriched with fossil sources (48.0 ± 9.0% vs. 30.3 ± 13.9%) but depleted in 13C (δ13C: −25.6 ± 0.9‰ vs. −22.4 ± 1.0‰) relative to non‐HULIS‐C. This suggests that the fossil components in HULIS are more recalcitrant to oxidative aging and exhibit higher light‐absorbing capacity, while the non‐fossil organic carbon is more likely to be oxidatively bleached into small, colorless, and highly polar molecules (i.e., non‐HULIS). Aromatic components are the major strong light‐absorbing fossil components in HULIS, dominantly originating from coal combustion (>77%). Non‐negative matrix factorization model showed that aromatic molecules from coal combustion have higher molecular weight and lower oxidation levels than biomass burning, potentially making them to be photo‐recalcitrant compounds. Our finding that coal combustion‐derived BrC maybe more persistent in the atmosphere and has greater long‐term impact on climate than BrC derived from biomass burning is an important consideration in climate models and mitigation policies. Plain Language Summary: Both the loading and light‐absorbing capacity of water‐soluble brown carbon (WSBrC) are high in China, but little is known about sources and atmospheric processes of strong light‐absorbing components in WSBrC. Humic‐like substances (HULIS) account for a significant fraction of light absorption by WSBrC, which may contain strong light‐absorbing components. Through dual carbon isotopic analysis, we discovered that HULIS‐C from 10 Chinese cities had relatively higher fossil sources contribution but lower δ13C values compared to non‐HULIS‐C. This indicates that the fossil components in HULIS not only possess a higher light‐absorbing capacity but are also more resistant to oxidative aging than non‐fossil components. The higher light‐absorbing capacity and resilience of fossil components can be attributed to the enrichment of aromatic compounds derived from coal combustion. Using the non‐negative matrix factorization model, we found that coal combustion tends to generate aromatic compounds with higher molecular weight and lower oxidation‐to‐carbon (O/C: 0.31 ± 0.03 vs. 0.50 ± 0.07) ratios than biomass burning. This characteristic may contribute to the recalcitrant property of coal combustion‐derived HULIS. Our findings highlight that coal combustion‐derived BrC may persists longer in the atmosphere and has a greater long‐term impact on climate than that derived from biomass burning. [ABSTRACT FROM AUTHOR]

The Bohai Sea (BS) region, an area of China that is severely polluted with atmospheric polycyclic aromatic hydrocarbons (PAHs), has received wide attention in recent decades. To characterize the variations of the concentrations and sources of PAHs from June 2014 to May 2019, 15 PAH congeners (Σ15PAHs) were measured in atmospheric samples (N = 228) collected at 12 sites around the BS, and the health risk and direct medical costs associated with lung cancer caused by exposure to PAHs were also estimated. The annual daily average concentration of Σ15PAHs was 56.78 ± 4.75 ngm-3 , which was dominated by low molecular weight PAHs (LMW-PAHs) containing three rings (58.7 ± 7.8 %). During the 5-year sampling period, the atmospheric Σ15PAHs concentration reduced by 17.5 % for the whole BS region, with an especially large drop of 51.7 % observed in the tightly controlled area of Tianjin (TJ), which was mainly due to a decrease in the concentration of high molecular weight PAHs (HMW-PAHs) containing five or six rings. Generally, the concentration of Σ15PAHs was highest in winter and lowest in summer, which can mainly be attributed to the change in LMW-PAH concentration. Based on the positive matrix factorization (PMF) model, PAHs in the BS region were mainly ascribed to coal combustion and biomass burning. The PAH contributions of coal combustion and motor vehicles showed different trends for the BS region (PAHs from coal combustion rose by 7.2 % and PAHs from motor vehicles fell by 22.4 %) and for TJ (PAHs from coal combustion fell by 12.6 % and PAHs from motor vehicles rose by 6.9 %). The incidence of lung cancer (ILCR) caused by exposure to atmospheric PAHs decreased by 74.1 % and 91.6 % from 2014 to 2018 in the BS region and in TJ, respectively. This was mainly due to the decrease in the concentration of highly toxic HMW-PAHs and was reflected in USD 10.7 million of savings in direct medical costs of lung cancer caused by exposure to PAHs, which represent a decrease of 46.1 % compared to the corresponding costs before air pollution prevention and control was implemented around the BS. There was an even higher reduction in medical costs of 54.5 % in TJ. Hence, this study proves that implementing pollution prevention and control not only effectively reduced the concentration of pollutants and the risks caused by them, but it also significantly reduced the medical costs of diseases caused by the corresponding exposure. [ABSTRACT FROM AUTHOR]

Plant height is a key agronomic trait that affects yield and is controlled by both phytohormone gibberellin (GA) and ultraviolet-B (UV-B) irradiation. However, whether and how plant height is modulated by UV-B-mediated changes in GA metabolism are not well understood. It has not been reported that the E3 ubiquitin ligase Anaphase Promoting Complex/Cyclosome (APC/C) is involved in the regulation of plant growth in response to environmental factors. We perform a forward genetic screen in soybean and find that a mutation in Glycine max Increased Leaf Petiole Angle1 (GmILPA1), encoding a subunit of the APC/C, lead to dwarfism under UV-B irradiation. UV-B promotes the accumulation of GmILPA1, which ubiquitinate the GA catabolic enzyme GA2 OXIDASE-like (GmGA2ox-like), resulting in its degradation in a UV-B-dependent manner. Another E3 ligase, GmUBL1, also ubiquitinate GmGA2ox-like and enhance the GmILPA1-mediated degradation of GmGA2ox-like, which suggest that GmILPA1-GmGA2ox-like module counteract the UV-B-mediated reduction of bioactive GAs. We also determine that GmILPA1 is a target of selection during soybean domestication and breeding. The deletion (Indel-665) in the promoter might facilitate the adaptation of soybean to high UV-B irradiation. This study indicates that an evolutionary GmILPA1 variant has the capability to develop ideal plant architecture with soybean cultivars. Gibberellins (GA) negatively regulate UVB-mediated suppression of plant height in plants. Here, the authors show that GmILPA1-mediated degradation of GmGA2ox-like protein counteract the UV-B-mediated reduction of bioactive GAs contributing to the linkage between the affection of UV-B and GA on plant height of soybean. [ABSTRACT FROM AUTHOR]

This study was designed to assess the distribution of organochlorines (OCs) in fish species, their spatio-temporal variations, bioaccumulation potential, and associated human health risks via dietary intake. The levels of twenty-three organochlorine pesticides (OCPs) and thirty-five polychlorinated biphenyls (PCBs) were analyzed in six fish species collected from the riverine ecosystem of Punjab Province, Pakistan. The results indicated that the mean levels of Σ23OCPs were 74.1 ng/g ww and 184 ng/g ww, and for Σ35PCBs the levels were 38.8 ng/g ww and 74.8 ng/g ww in herbivorous and carnivorous fish species, respectively. The most abundant contaminants in all fish species were DDTs (65%) and HCHs (14%) among OCPs and heavier PCB congeners (62%) among PCBs. As for dioxin-like PCBs, the WHO toxic equivalency values (ng TEQ/g ww) were in the range of 0.21 (Cyprinus Carpio) to 2.38 (Rita Rita), exceeding the maximum allowable limit of 0.004 ng TEQ/g, ww by the European Commission. Spatio-temporal analysis indicated relatively higher OC levels in winter season with elevated concentrations in fish samples from industrial zone. The bioconcentration factor (L/kg) values ranged from 723 to 2773 for PCBs and 315 to 923 for OCPs in all fish species, with higher levels were reported in carnivorous species. The human health risk assessment at both 50th and 95th percentiles revealed the absence of any significant non-carcinogenic risk as calculated HR was less than 1. However, the critical carcinogenic risk was found to be associated for most of the contaminants, signifying the dietary exposure to OCPs and PCBs might pose the public health concern. [ABSTRACT FROM AUTHOR]

The Bohai Sea (BS) as the most polluted area of PAHs in China has been received wide attention in recent decades. To characterize the variations of concentrations and sources of PAHs from June 2014 to May 2019, fifteen congeners of PAHs (∑15PAHs) were measured from atmospheric samples (N=228) collected at 12 sites around the BS, and health risk and direct medical costs associated with lung cancer exposed to PAHs were also estimated. The annual daily average concentration of ∑15PAHs was 56.8 ± 4.7 ng m-3, dominated by low molecular weight (LMW-PAHs, 3-ring) (58.9 ± 7.8 %). During the five-year sampling period, the atmospheric ∑15PAHs concentration reduced by 17.5 % for the whole BS, especially in the tightly controlled area of Tianjin (TJ) with a drop of 51.7 %, which was mainly due to the decrease of high molec-ular weight PAHs (HMW-PAHs, 5-6 ring) concentration. Generally, the concentration of ∑15PAHs was highest in winter and lowest in summer, mainly attributed to the change of LMW-PAHs concentration. Based on PMF model, PAHs at the BS were mainly ascribed to coal combustion and biomass burning. And the contribution of coal combustion and motor vehicle to PAHs had a different performance between the BS (coal combustion rose by 6.7 %, motor vehi-cle fell by 22.7 %) and TJ (coal combustion fell by 13.2 %, motor vehicle rose by 6.7 %). The in-cidence of lung cancer (ILCR) caused by exposing to atmospheric PAHs at the BS and TJ de-creased by 74.1 % and 91.6 % from 2014 to 2018, respectively. That was mainly due to the de-crease of the concentration of highly toxic HMW-PAHs. It was reflected on the savings of $10.7 million in direct medical costs of lung cancer exposed PAHs, which was accounted 46.1 % before air prevention and control around the BS. And there was a higher cost reduction of 54.5 % in TJ. Hence, this study proved that implementing pollution prevention and control not only effective-ly reduced the concentration of pollutants and the caused risks, but also significantly reduced the medical costs of diseases caused by corresponding expose. [ABSTRACT FROM AUTHOR]

Excitation-emission matrix (EEM) fluorescence spectroscopy has been widely used to characterize chemical components of brown carbon (BrC), yet the molecular basics and formation mechanisms of chromophores decomposed by parallel factor (PARAFAC) analysis are not fully understood. Here, water-soluble organic carbon (WSOC) in aerosols from Karachi, Pakistan, were characterized with EEM spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Three PARAFAC components were identified, including two humic-like (C1 and C2), and one protein-like (C3) species. Among them, the C2 shows the longest emission maxima (~494 nm), and correlates tightly with the mass absorption efficiency at 365 nm (MAE365), the character of BrC. Molecular families associated with each of the three components were determined by Spearman correlation analysis between FT-ICR MS peaks and PARAFAC component intensities. The C1 and C2 components are associated with nitrogen-enriched compounds, despite that C2 more with higher aromaticity, higher N content, and highly oxygenated compounds. The formulas associated with C3 include fewer nitrogen-containing species, with a lower unsaturated degree and oxidation state. A dominant oxidation pathway for the formation of C1 and C2 components was suggested, notwithstanding their different precursor types. A large number of formulas associated with C2 were found to be located in the "potential BrC" region, overlapped with BrC-associated formulas, and readily correlated tightly with MAE365. This suggests that the compounds illuminating C2 may have also contributed substantially to the BrC light absorption. These findings were important for future studies using the EEM-PARAFAC method to explore the compositions, processes, and sources of atmospheric BrC. [ABSTRACT FROM AUTHOR]

The aim of the present study was to determine the occurrence, spatio-temporal variations, source apportioning, and ecological risk assessment of selected PCBs and OCPs in surface water and sediments collected riverine environment of Punjab province, Pakistan. The concentration of ΣOCPs (water: 64–455 ng/L; sediments: 117–616 ng/g) and ΣPCBs (water: 2–132 ng/L; sediments: 3.27–200 ng/g) was found comparatively higher than the levels reported from other parts of the world. The higher concentrations of DDTs and HCHs were detected in both studied matrices, whereas among PCBs, CB-28, 49 and CB-37, 82 were dominant in water and sediments, respectively. The isomeric ratios including α-HCH/γ-HCH, (DDE + DDD) / DDTs, and α /β-endosulfan reflected the recent use of lindane, technical DDT, and endosulfan in the study area. The WHO–TEQ values of DL-PCBs ranged from 3.6 × 10−6 to 0.115 ng/L and 8.7 × 10−6 to 0.157 ng/g in surface water and sediments in both seasons, respectively. The spatial variation analysis revealed that the sites in the industrial and agricultural zones were highly contaminated. The OCPs and PCBs fluxes to downstream areas were estimated to be 12.4 tons/year and 1.9 tons/year, respectively. The significant ecological risks were estimated to be posed by OCPs and PCBs, as their levels in 67% and 62% of surface water and sediment samples were exceeding the threshold limits, highlighting effects to ecological integrities. [ABSTRACT FROM AUTHOR]

Secondary organic aerosols (SOAs) are important components of fine particulates in the atmosphere. However, the sources of SOA precursor and atmospheric processes affecting SOAs are poorly understood. This limits our abilities to improve air quality and model aerosol-mediated climate forcing. Here, we use novel compound-specific dual-carbon isotope fingerprints (Δ14 C and δ13 C) for individual SOA tracer molecules (i.e., oxalic acid) to investigate the fates of SOAs in the atmosphere at five emission hotspots in China. Coal combustion and vehicle exhaust accounted for ∼ 55 % of the sources of carbon in oxalic acid in Beijing and Shanghai, but biomass burning and biogenic emissions accounted for ∼ 70 % of the sources of carbon in oxalic acid in Chengdu, Guangzhou, and Wuhan during the sampling period. The dual-carbon isotope signatures of oxalic acid and bulk organic carbon pools (e.g., water-soluble organic carbon) were compared to investigate the fates of SOAs in the atmosphere. Photochemical aging and aqueous-phase chemical processes dominate the formation of oxalic acid in summer and in winter, respectively. The results indicated that SOA carbon sources and chemical processes producing SOAs vary spatially and seasonally, and these variations need to be included in Chinese climate projection models and air quality management practices. [ABSTRACT FROM AUTHOR]

Incomplete understanding of the sources of secondary organic aerosol (SOA) leads to large uncertainty in both air quality management and in climate change assessment. Chemical reactions occurring in the atmospheric aqueous phase represent an important source of SOA mass, yet, the effects of anthropogenic emissions on the aqueous SOA (aqSOA) are not well constrained. Here we use compound-specific dual-carbon isotopic fingerprints (δ13C and Δ14C) of dominant aqSOA molecules, such as oxalic acid, to track the precursor sources and formation mechanisms of aqSOA. Substantial stable carbon isotope fractionation of aqSOA molecules provides robust evidence for extensive aqueous-phase processing. Contrary to the paradigm that these aqSOA compounds are largely biogenic, radiocarbon-based source apportionments show that fossil precursors produced over one-half of the aqSOA molecules. Large fractions of fossil-derived aqSOA contribute substantially to the total water-soluble organic aerosol load and hence impact projections of both air quality and anthropogenic radiative forcing. Our findings reveal the importance of fossil emissions for aqSOA with effects on climate and air quality. Isotope fingerprinting is used to track precursor sources and formation pathways of aqueous SOA, such as oxalic acid, finding that fossil fuel precursors contributions have largely been underestimated. [ABSTRACT FROM AUTHOR]

In the context of China's agricultural labor shortage and the pressure of aging, this paper uses the land fragmentation index and the intermediary efficiency model to measure the degree of land fragmentation based on farmer-level data from the main garlic producing area in Lanling County in Shandong Province in 2020. The direct effect of labor structure on land-use efficiency and the mediating effect through land fragmentation are analyzed. The research results show that: (1) the average land-use efficiency of the sample farmers is relatively low; (2) the change in labor structure has an "inverted U"-shaped direct effect on land-use efficiency; and (3) the change in land fragmentation in the labor structure has a direct effect on land-use efficiency. The influence of land-use efficiency played a nonlinear mediating effect. The change in labor structure with the degree of land fragmentation showed an "inverted U"-shaped relationship, and the degree of land fragmentation and land-use efficiency had a "U"-shaped relationship. In order to improve land-use efficiency, two aspects of policy support should be increased: encouraging farmers to integrate land and supporting specialized and diversified planting. [ABSTRACT FROM AUTHOR]

Organosulfur compounds (OrgSs), especially organosulfates, have been widely reported to be present in large quantities in particulate organic matter found in various atmospheric environments. Despite hundreds of organosulfates and their formation mechanisms being previously identified, a large fraction of OrgSs remain unexplained at the molecular level, and a better understanding of their formation pathways and critical environmental parameters is required to explain the variations in their concentrations. In this study, the abundance and molecular composition of OrgSs in fine particulate samples collected in Guangzhou were reported. The results revealed that the ratio of the annual average mass of organic sulfur to total particulate sulfur was 33 ± 12 %, and organic sulfur had positive correlations with SO 2 (r=0.37 , p<0.05) and oxidant (NO x + O 3 , r=0.40 , p<0.01). A Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) analysis revealed that more than 80 % of the sulfur-containing formulas detected in the samples had the elemental composition of o/(4s+3n)≥1 , indicating that they were largely in the form of oxidized organosulfates or nitrooxy organosulfates. Many OrgSs that were previously tentatively identified as having biogenic or anthropogenic origins were also present in freshly emitted aerosols derived from combustion sources. The results indicated that the formation of OrgSs through an epoxide intermediate pathway could account for up to 46 % of OrgSs from an upper bound estimation, and the oxidant levels could explain 20 % of the variation in the mass of organic sulfur. The analysis of our large dataset of FT-ICR MS results suggested that relative humidity, oxidation of biogenic volatile organic compounds via ozonolysis, and NO x -related nitrooxy organosulfate formation were the major reasons for the molecular variation of OrgSs, possibly highlighting the importance of the acid-catalyzed ring-opening of epoxides, oxidation processes, and heterogeneous reactions involving either the uptake of SO 2 or the heterogeneous oxidation of particulate organosulfates into additional unrecognized OrgSs. [ABSTRACT FROM AUTHOR]

Atmospheric nitrogen‐containing organic compounds (NOCs) are critical components of global nitrogen deposition and light‐absorption species. The sources and compositions of NOCs are complex and remain largely unknown. Here, NOCs in 55 ambient aerosol samples collected in Guangzhou, South China, were analyzed via ultrahigh‐resolution Fourier transform ion cyclotron resonance mass spectrometry in negative‐ion and positive‐ion electrospray ionization (ESI) modes. The molecular compositions of NOCs measured via ESI– and ESI+ exhibited considerable differences. NOCs detected in the negative mode were mainly composed of highly oxygenated organic nitrates (O/N = 6), whereas NOCs detected in the positive mode were mainly composed of reduced nitrogen‐containing compounds (e.g., amides and amino acids). CHN compounds potentially corresponding to amines and alkaloids showed low abundance in the detection modes. Non‐metric multidimensional scaling and individual compound correlation analyses showed that the molecular compositions of NOCs were mainly affected by anthropogenic activities and meteorological parameters. For example, anthropogenic activities such as biomass burning and secondary nitrogen‐chemistry processes led to the accumulation of aromatic and highly oxygenated NOCs during winter. During summer, higher OH radical concentrations and temperatures will result in more prevalent or persistent reduced aliphatic NOCs, particularly lipid‐like amines. Some variables (e.g., relative humidity) have distinct effects on the variation of different types of NOCs. More research is needed to reveal the influencing mechanisms. This study clarifies the molecular compositions of NOCs and the mechanisms by which various factors influence the molecular variations. The findings can guide the assessment of NOCs evolution and deposition. Plain Language Summary: Negative and positive electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry (ESI‐FT‐ICR‐MS) was used to characterize the molecular composition of nitrogen‐containing organic compounds (NOCs) from aerosol samples in Guangzhou. It was determined that a large amount of various NOCs are present in the samples, with NOCs in highly oxidative and reduced states can be roughly identified by distinct ionization modes. By combining the ESI‐FT‐ICR‐MS results and statistical analysis, the factors that associated with the distribution of NOCs and how these factors worked were identified. Anthropogenic activities and meteorological parameters (e.g., temperature and oxidation levels) are the two important drivers that led to the variations of NOCs, resulting to inverse molecular patterns with different response to aromatic/highly unsaturated and saturated structures, respectively. This study provides a useful clue for studying NOCs in complex system, bridges the links between the filed observation and knowledge about sources and formation pathways of NOCs that derived from controlled laboratory studies. Key Points: Most of identified CHON− species had O/N ≥ 3 and showed higher O/C ratios than CHON+ species; CHN only constituted small fraction of nitrogen‐containing organic compounds (NOCs)Biomass burning and secondary inorganic‐nitrogen processes lead to the accumulation of aromatic and phenolic NOCs during winterHigher OH radical concentrations and temperatures result in more prevalent or persistent reduced aliphatic NOCs in summer [ABSTRACT FROM AUTHOR]

Oxidative stress is a key mechanism by which ambient particulate matter induces adverse health effects. Most studies have focused on the oxidative potential (OP) of water-soluble constituents, while there has been limited work on the OP of solvent-extractable organic matter (EOM OP). In this study, the EOM OP of ambient total suspended particulate (TSP) from Bangkok, Thailand, was determined using the dithiothreitol (DTT) assay. Positive matrix factorization (PMF), combined with chemical analysis of molecular markers, was employed to apportion the contributions of various emission sources to EOM OP. The volume-normalized OP initially increased with organic carbon (OC) concentration and plateaued gradually, while the mass-normalized OP fitted well with OC concentration using a power function. Fossil fuel combustion (62%) and plastic waste burning (23%) were the major contributors to EOM OP, while biomass burning demonstrated only a limited contribution. EOM OP correlated well with each group of polycyclic aromatic hydrocarbons (PAHs), suggesting that secondary formation of quinones associated with fossil fuel combustion and plastic waste burning could be an important pathway of TSP toxicity. This study underscores the importance of considering different emission sources when evaluating potential health impacts and the implementation of air pollution regulations. [ABSTRACT FROM AUTHOR]

Municipal solid waste incineration products of bottom ash (BA), fly ash (FA), and pickling sludge (PS), causing severe environmental pollution, were transformed into glass ceramic foams with the aid of CaCO3 as a pore-foaming agent during sintering. The effect of the BA/FA mass ratio on the phase composition, pore morphology, pore size distribution, physical properties, and glass structure was investigated, with results showing that with the increase in the BA/FA ratio, the content of the glass phase, Si-O-Si, and Q3Si units decrease gradually. The glass transmission temperature of the mixture was also reduced. When combined, the glass viscosity decreases, causing bubble coalescence and uneven pore distribution. Glass ceramic foams with uniform spherical pores are fabricated. When the content of BA, FA, and PS are 35wt%, 45wt%, and 20wt%, respectively, contributing to high performance glass ceramic foams with a bulk density of 1.76 g/cm3, porosity of 56.01%, and compressive strength exceeding 16.23 MPa. This versatile and low-cost approach provides new insight into synergistically recycling solid wastes. [ABSTRACT FROM AUTHOR]

The mobility of arsenic (As) in soil depends on its sorption/desorption processes on soil particles. Plant uptake locally lowers As concentration in soil pore water, which would trigger resupplies of As from soil solid phase. To better understand the fate of As in soil system after its inputs into soil and its subsequent dynamic processes, diffusive gradients in thin films (DGT) technique along with DGT-induced fluxes in soils (DIFS) model were introduced to study the kinetic information of As in soils, including its response time (TC) and resupply rate constant (k−1). To achieve a series of soils with gradient As level, two different types of soils with similar As level (total As in soil JL is 7.4 mg kg−1, while in soil BJ is 6.5 mg kg−1) were collected and amended with exogenous As. Then, DGT deployments were carried out following a period of 90-day soil incubation. The simulated TC values in non-amended soil JL and soil BJ were 0.036 and 0.001 s−1, respectively. The difference may due to the properties of these two soils, including pH values and contents of adsorption materials, such as Fe and Al compounds. After As inputs into soils, the intrinsic rate of As release from the solid phase to the solution phase in As-amended JL soil was much higher than that in non-amended soil. While for soil BJ, a decreasing trend was observed after As spiking. The redistribution of As may responsible for the different variation trends of As kinetics in these two soils after As spiking. The results indicated that the distribution coefficient of As (Kd) in soil was mainly affected by soil Olsen-P content due to an ubiquitous competition between P and As on soil particles. [ABSTRACT FROM AUTHOR]

Most existing wireless networking solutions are best-effort and do not provide any delay guarantee required by important applications, such as mobile multimedia conferencing and real-time control of cyber-physical systems. Recently, Hou and Kumar provided a novel framework for analyzing and designing delay-guaranteed wireless networking solutions. While inspiring, their idle-time-based analysis applies only to flows with a special traffic pattern called the frame-synchronized setting. The problem remains largely open for general traffic patterns. This paper addresses this challenge by proposing a general framework that characterizes and achieves the complete delay-constrained capacity region with general traffic patterns in single-hop downlink access-point wireless networks. We first show that the timely wireless flow problem is fundamentally an infinite-horizon Markov decision process (MDP). Then, we judiciously combine different simplification methods to prove that the timely capacity region can be characterized by a finite-size convex polygon. This for the first time allows us to characterize the timely capacity region of wireless flows with general traffic patterns. We then design three scheduling policies to optimize network utility and/or support feasible timely throughput vectors for general traffic patterns. The first policy achieves the optimal network utility and supports any feasible timely throughput vector but suffers from the curse of dimensionality. The second and third policies are inspired by our MDP framework and are of much lower complexity. Simulation results show that both achieve near-optimal performance and outperform other existing alternatives. [ABSTRACT FROM PUBLISHER]

In this paper, novel three-dimensional (3D) CuO precursor was synthesized under the ice water bath. The flower-like micellar polyp-phenylenediamine (PpPD) was synthesized when the p-phenylenediamine-salicylic acid ([SA]/PPD) ratio was 1:1. The two amino groups of PpPD interacted with Cu by the coordination interactions. After calcination in the air, dandelion-like CuO nanoflowers were successfully prepared. The physicochemical properties of the as-prepared CuO were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), infrared spectrometer (FT-IR), UV-vis absorption spectra (UV-vis), and energy-dispersive spectrometer (EDS). In the participation of HO, the as-obtained CuO nanoflowers exhibited high efficiency on the decolorization of rhodamine B (RhB) by the synergy of ·OH and ·O . The novel dandelion-like CuO also provided more active sites to improve the photocatalytic effect. It can be applied to the degradation of dyes, such as RhB, and plays a role in environmental pollution control. [ABSTRACT FROM AUTHOR]

ABSTRACT Because of the great demand for fluorescent materials, fluorescent dyes, semiconductor quantum dots, and carbon-based quantum dots have been studied extensively. However, the poor photostability and potential biological toxicity need to be resolved. In this study, we demonstrated the synthesis of a new biomass quantum dot, the polydopamine dot (PDADs), via a simple hydrothermal method under an acidic environment. This new biomass quantum dot showed not only remarkable photoluminescence properties (quantum yield = 0.93) but also a high stability and low toxicity. Moreover, these PDADs could be used as a fluorescent probe for the rapid detection of Cr(VI) (response time = 0.01 s). The detection limit (1 × 10−11 M) is the lowest detection limit reported for Cr(VI) fluorescent probes. The mechanism efficient quenching progress could have been due to the fast redox progress between the PDADs and Cr(VI). Moreover, we also showed a practical application of PDADs for Cr(VI) detection in vitro. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44784. [ABSTRACT FROM AUTHOR]

In this work, o-phenylenediamine-m-phenylenediamine copolymer dots (omCPs) with designed surface groups are synthesized and characterized. Here, we explored a simple, rapid semiquantitative detection system for Cu2+ with a wide detection range (5–7 orders of magnitude) based on the fluorescence in the solid state of omCPs and their tunable detection limits. The construction and application of the rapid semiquantitative detection system for Cu2+ are developed and demonstrated for the practical applications. What’s more, the detection limit can be modulated easily by adjusting the surface groups of these dots through the monomer dose control before the co-polymerization. Moreover, we demonstrated that this new technological approach is suitable for the semiquantitative determination of other ions pollutants (i.e., Na+, K+, Cu2+, Pb2+, Hg2+, and NO2−) in environmental water. [ABSTRACT FROM AUTHOR]

In this paper, we study the problem of link scheduling for multi-hop wireless networks with per-flow delay constraints under the K-hop interference model. Specifically, we are interested in algorithms that maximize the asymptotic decay-rate of the probability with which the maximum end-to-end backlog among all flows exceeds a threshold, as the threshold becomes large. We provide both positive and negative results in this direction. By minimizing the drift of the maximum end-to-end backlog in the converge-cast on a tree, we design an algorithm, Largest-Weight-First (LWF), that achieves the optimal asymptotic decay-rate for the overflow probability of the maximum end-to-end backlog as the threshold becomes large. However, such a drift minimization algorithm may not exist for general networks. We provide an example in which no algorithm can minimize the drift of the maximum end-to-end backlog. Finally, we simulate the LWF algorithm together with a well known algorithm (the back-pressure algorithm) and a large-deviations optimal algorithm in terms of the sum-queue (the P-TREE algorithm) in converge-cast networks. Our simulation shows that our algorithm performs significantly better not only in terms of asymptotic decay-rate, but also in terms of the actual overflow probability. [ABSTRACT FROM AUTHOR]

We study the delay performance in large-scale wireless multihop networks with unreliable links from percolation perspective. Previous works have showed that the end-to-end delay scales linearly with the source-to-destination distance, and thus the delay performance can be characterized by the delay–distance ratio \gamma. However, the range of \gamma, which may be the most important parameter for delay, remains unknown. We expect that \gamma may depend heavily on the node density \lambda of a wireless multihop network. In this paper, we investigate the fundamental relationship between \gamma and \lambda. Obtaining the exact value of \gamma(\lambda) is extremely hard, mainly because of the dynamically changing network topologies caused by the link unreliability. Instead, we provide both upper bound and lower bound to the delay–distance ratio \gamma(\lambda). Simulations are conducted to verify our theoretical analysis. [ABSTRACT FROM PUBLISHER]

While the aging of agricultural labor force and its impact on agricultural production have been attracting extensive attention, little is known about the relationship between aging of agricultural labor force and technical efficiency in the garlic production. Based on the survey data of garlic growers in Lanling County, Shandong Province, the Data envelopment analysis (DEA) model is used to measure the production technical efficiency of garlic growers in 84 villages in Lanling County, Shandong Province, with the aging of the labor force. The distribution characteristics and changing trends of garlic production technology efficiency are analyzed in terms of family characteristics and garlic planting characteristics, and regression analysis is performed on the differences of the results. The study found the following: (1) Garlic growers in Lanling County, Shandong Province, accounted for a high proportion of laborers over 60 years old, and their physical health status was weaker than that of young laborers, which reduced the technical efficiency of garlic planting and production. (2) The number of garlic varieties grown by garlic growers and the number of garlic planted in acres have a significant negative impact on the technical efficiency of garlic planting by farmers. (3) There is a significant positive correlation between the annual household income of farmers and the production technology efficiency of garlic growers; when the number of garlic training is not more than three times, it has a positive impact on the production technology efficiency of garlic planting by farmers, and more than three times are related to garlic production technology. The efficiency is negatively correlated. [ABSTRACT FROM AUTHOR]

Mobile devices have steadily gained acceptance as a multimedia platform, not only that, one of the most valuable pieces of contextual information for an intelligent mobile application is the user's location. The university campus is an interesting application environment for location-based and context-aware mobile services: wherever the students are, they are eager to announce to others and want to know what happens in the university campus, even alumni always care about the latest in his or her campus. The Campus View, what is described in this article, is a smart-phone based context and location-aware video sharing mobile application implemented on Android 2.1. It first gives a full panorama to one Chinese university campus, which will provide a campus overview and variations to alumni and potential students. Different from Street-view of Google which was only created once and demands not to drive anywhere more than once, our campus panorama is timely updated by our DIYed Street-view camera. What's more, the application users inside the campus can use it to recode the latest happenstance and then upload the video short with Geo-information to the server. The recoded video short will be further shared as a H. 264 stream attached to a specific panorama. This paper presents the development framework of Campus View application and an evaluation of key framework components to assess their consumption of mobile device's resources. [ABSTRACT FROM AUTHOR]

By taking into account the valence electron number and periodic number of constituting metals, a new method is first proposed to calculate the structural enthalpy in the Miedema's model and the modified Miedema's model is then used to predict the formation of metastable phases in Ni-Ti system. To testify the relevance of the present prediction, the multilayered films of NiTi ( x=27.3, 30.5, 42.4, 83.1, 89) are prepared and irradiated by 200 keV xenon ions. Experiment results reveal that uniform amorphous phases are obtained in the NiTi, NiTi, and NiTi films by increasing the irradiation dose. While for the NiTi and NiTi films, an hcp Ti-based solid solution phase and a bcc Ti-rich solid solution phase coexist upon irradiation dose higher than 6×10 Xe/cm. The predictions of relative stabilities of metastable phases in Ni-Ti system by the modified Miedema's model match well with IBM experiments, thus justifying the modification proposed in the present study. [ABSTRACT FROM AUTHOR]

Eva-1 homolog A (EVA1A) is regarded as TMEM166 (transmembrane protein 166) or FAM176A (family with sequence similarity 176) and a lysosome and endoplasmic reticulum-associated protein involved in regulating autophagy and apoptosis. EVA1A regulates embryonic neurogenesis, cardiac remodeling, islet alpha-cell functions, acute liver failure, and hepatitis B virus replication. However, the related mechanisms are not fully clear. Autophagy is a process in which cells transfer pathogens, abnormal proteins and organelles to lysosomes for degradation. It plays an important role in various physiological and pathological processes, including cancer, aging, neurodegeneration, infection, heart disease, development, cell differentiation and nutritional starvation. Recently, there are many studies on the important role of EVA1A in many physiological and pathological processes by regulating autophagy. However, the related molecular mechanisms need further study. Therefore, we summarize the above-mentioned researches about the role of EVA1A in physiological and pathological processes through regulating autophagy in order to provide theoretical basis for future researches. [ABSTRACT FROM AUTHOR]

Mobile activity recognition is significant to the development of human-centric pervasive applications including elderly care, personalized recommendations, etc. Nevertheless, the distribution of inertial sensor data can be influenced to a great extent by varying users. This means that the performance of an activity recognition classifier trained by one user’s dataset will degenerate when transferred to others. In this study, we focus on building a personalized classifier to detect four categories of human activities: light intensity activity, moderate intensity activity, vigorous intensity activity, and fall. In order to solve the problem caused by different distributions of inertial sensor signals, a user-adaptive algorithm based on K-Means clustering, local outlier factor (LOF), and multivariate Gaussian distribution (MGD) is proposed. To automatically cluster and annotate a specific user’s activity data, an improved K-Means algorithm with a novel initialization method is designed. By quantifying the samples’ informative degree in a labeled individual dataset, the most profitable samples can be selected for activity recognition model adaption. Through experiments, we conclude that our proposed models can adapt to new users with good recognition performance. [ABSTRACT FROM AUTHOR]