The cornea is a special interface between the internal ocular tissue and the external environment that provides a powerful chemical, physical, and biological barrier against the invasion of harmful ...substances and pathogenic microbes. This protective effect is determined by the unique anatomical structure and cellular composition of the cornea, especially its locally resident innate immune cells, such as Langerhans cells (LCs), mast cells (MCs), macrophages, γδ T lymphocytes, and innate lymphoid cells. Recent studies have demonstrated the importance of these immune cells in terms of producing different cytokines and other growth factors in corneal homeostasis and its pathologic conditions. This review paper briefly describes the latest information on these resident immune cells by specifically analyzing research from our laboratory.
Porous CuO nanosheets were prepared on alumina tubes using a facile hydrothermal method, and their morphology, microstructure, and gas-sensing properties were investigated. The monoclinic CuO ...nanosheets had an average thickness of 62.5 nm and were embedded with numerous holes with diameters ranging from 5 to 17 nm. The porous CuO nanosheets were used to fabricate gas sensors to detect hydrogen sulfide (H2S) operating at room temperature. The sensor showed a good response sensitivity of 1.25 with respond/recovery times of 234 and 76 s, respectively, when tested with the H2S concentrations as low as 10 ppb. It also showed a remarkably high selectivity to the H2S, but only minor responses to other gases such as SO2, NO, NO2, H2, CO, and C2H5OH. The working principle of the porous CuO nanosheet based sensor to detect the H2S was identified to be the phase transition from semiconducting CuO to a metallic conducting CuS.
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•The sources, compositions, distributions, and sinks of indoor VOCs are reviewed.•The major factors driving indoor VOC chemistry are summarized.•The future research directions on ...indoor VOCs are proposed.
Gaseous organic compounds, mainly volatile organic compounds (VOCs), have become a wide concern in various indoor environments where we spend the majority of our daily time. The sources, compositions, variations, and sinks of indoor VOCs are extremely complex, and their potential impacts on human health are less understood. Owing to the deployment of the state-of-the-art real-time mass spectrometry during the last two decades, our understanding of the sources, dynamic changes and chemical transformations of VOCs indoors has been significantly improved. This review aims to summarize the key findings from mass spectrometry measurements in recent indoor studies including residence, classroom, office, sports center, etc. The sources and sinks, compositions and distributions of indoor VOCs, and the factors (e.g., human activities, air exchange rate, temperature and humidity) driving the changes in indoor VOCs are discussed. The physical and chemical processes of gas-particle partitioning and secondary oxidation processes of VOCs, and their impacts on human health are summarized. Finally, the recommendations for future research directions on indoor VOCs measurements and indoor chemistry are proposed.
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CuCo2S4 is regarded as a promising electrode material for supercapacitor, but has inferior conductivity and poor cyclic stability which restrict its wide-range applications. In this ...work, hierarchically hybrid composite of CuCo2S4/carbon nanotubes (CNTs) was synthesized using a facile hydrothermal and sulfuration process. The embedded CNTs in the CuCo2S4 matrix provided numerous effective paths for electron transfer and ion diffusion, and thus promoted the faradaic reactions of the CuCo2S4 electrode in the energy storage processes. The CuCo2S4/CNTs-3.2% electrode exhibited a significantly increased specific capacitance of 557.5 F g−1 compared with those of the pristine CuCo2S4 electrode (373.4 F g−1) and CuO/Co3O4/CNTs-3.2% electrode (356.5 F g−1) at a current density of 1 A g−1. An asymmetric supercapacitor (ASC) was assembled using the CuCo2S4/CNTs-3.2% as the positive electrode and the active carbon as the negative electrode, which exhibited an energy density of 23.2 Wh kg−1 at a power density of 402.7 W kg−1. Moreover, the residual specific capacitance of this ASC device retained 85.7% of its original value after tested for 10,000 cycles, indicating its excellent cycle stability.
The rapidly spread coronavirus disease (COVID-19) has limited people's outdoor activities and hence caused substantial reductions in anthropogenic emissions around the world. However, the air quality ...in some megacities has not been improved as expected due to the complex responses of aerosol chemistry to the changes in precursors and meteorology. Here we demonstrate the responses of primary and secondary aerosol species to the changes in anthropogenic emissions during the COVID-19 outbreak in Beijing, China along with the Chinese New Year (CNY) holiday effects on air pollution by using six-year aerosol particle composition measurements. Our results showed large reductions in primary aerosol species associated with traffic, cooking and coal combustion emissions by 30–50% on average during the CNY, while the decreases in secondary aerosol species were much small (5–12%). These results point towards a future challenge in mitigating secondary air pollution because the reduced gaseous precursors may not suppress secondary aerosol formation efficiently under stagnant meteorological conditions. By analyzing the long-term measurements from 2012 to 2020, we found considerable increases in the ratios of nitrate to sulfate, secondary to primary OA, and sulfur and nitrogen oxidation capacity despite the overall decreasing trends in mass concentrations of most aerosol species, suggesting that the decreases in anthropogenic emissions have facilitated secondary formation processes during the last decade. Therefore, a better understanding of the mechanisms driving the chemical responses of secondary aerosol to the changes in anthropogenic emissions under complex meteorological environment is essential for future mitigation of air pollution in China.
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•Different responses of primary and secondary species to the COVID-19 outbreak•30–50% decreases in primary aerosol species during the Chinese New Year holiday•Much smaller changes in secondary species compared with primary aerosol species•Large increases in sulfur and nitrogen oxidation capacity during the last decade
Abstract
The formation mechanism of aerosol sulfate during wintertime haze events in China is still largely unknown. As companions, SO
2
and transition metals are mainly emitted from coal combustion. ...Here, we argue that the transition metal-catalyzed oxidation of SO
2
on aerosol surfaces could be the dominant sulfate formation pathway and investigate this hypothesis by integrating chamber experiments, numerical simulations and in-field observations. Our analysis shows that the contribution of the manganese-catalyzed oxidation of SO
2
on aerosol surfaces is approximately one to two orders of magnitude larger than previously known routes, and contributes 69.2% ± 5.0% of the particulate sulfur production during haze events. This formation pathway could explain the missing source of sulfate and improve the understanding of atmospheric chemistry and climate change.
•Temperature warming significantly decreased soil labile organic C fractions.•Long-term organic manure application increased soil labile organic C fractions.•Long-term fertilization significantly ...affected soil enzyme activities.•Warming governed soil enzyme activities by altering labile organic C fractions.
The effects of temperature changes on soil organic carbon (SOC), labile organic carbon fractions (microbial biomass carbon, MBC; dissolved organic carbon, DOC; particulate organic carbon, POC), and enzyme activities under long-term fertilization regimes as well as their relationships at different temperatures were investigated in this study. Soil samples were collected in the fluvo-aquic soil of a 26-year fertilizer trial in the North China Plain after maize harvest in 2012, and four treatments were selected: control of no fertilizer (CK), standard rate of mineral fertilizer treatment (SMF), standard rate of organic manure treatment with N input rate equal to SMF (SMA), and half-standard rate of organic manure plus half-standard rate of mineral fertilizer treatment (1/2(SMA+SMF)). We determined soil chemical properties and labile organic carbon fractions using standard methods and the activities of nine soil enzymes involved in C, N, and P cycling in a 21-day incubation experiment at different temperatures (5°C, 15°C, 25°C, and 35°C) by micro-plate fluorometric assay. Additionally, we investigated the relationships among them using redundancy analyses (RDA) at four temperatures. The results indicated that (1) temperature, fertilization, and their interaction had significant effects on SOC, MBC, DOC, POC, and most of the soil enzyme activities; (2) long-term organic manure treatments (SMA and 1/2(SMA+SMF)) significantly improved SOC, MBC, DOC, and POC contents and seven hydrolytic enzyme activities (α-1,4-glucosidase, β-1,4-glucosidase, β-1,4-xylosidase, cellobiohydrolase, L-leucine aminopeptidase, β-1,4-N-acetylglucosaminidase, phosphatase) at different temperatures, compared with the mineral fertilized treatment (SMF) and CK. However, oxidoreductases (peroxidase and phenol oxidase) showed the opposite trend with hydrolytic enzyme activities and had higher values in SMF and CK treatments; (3) SOC, MBC, DOC, POC, and most of the soil enzyme activities decreased with increasing temperature; (4) RDA revealed that the dominant factors of SOC and soil labile organic carbon fractions affecting soil enzyme activities were POC and SOC at 5°C, DOC and POC at 15°C, DOC and SOC at 25°C, and MBC, DOC, and SOC at 35°C. In conclusion, temperature changes significantly altered soil enzyme activities by driving changes in the rates of SOC decomposition and the fractions of soil labile organic carbon. Our conclusions have clear implications for soil ecosystem and biogeochemical cycles under climate change.
Custom bus routes need to be optimized to meet the needs of a customized bus for personalized trips of different passengers. This paper introduced a customized bus routing problem in which trips for ...each depot are given, and each bus stop has a fixed time window within which trips should be completed. Treating a trip as a virtual stop was the first consideration in solving the school bus routing problem (SBRP). Then, the mixed load custom bus routing model was established with a time window that satisfies its requirement and the result were solved by Cplex software. Finally, a simple network diagram with three depots, four pickup stops, and five delivery stops was structured to verify the correctness of the model, and based on the actual example, the result is that all the buses ran 124.42 kilometers, the sum of kilometers was 10.35 kilometers less than before. The paths and departure times of the different busses that were provided by the model were evaluated to meet the needs of the given conditions, thus providing valuable information for actual work.
CeO2 nanowires were synthesized using a facile hydrothermal process without any surfactant, and their morphological, structural and gas sensing properties were systematically investigated. The CeO2 ...nanowires with an average diameter of 12.5 nm had a face-centered cubic fluorite structure and grew along 111 of CeO2. At the room temperature of 25 °C, hydrogen sulfide (H2S) gas sensor based on the CeO2 nanowires showed excellent sensitivity, low detection limit (50 ppb), and short response and recovery time (24 s and 15 s for 50 ppb H2S, respectively).
•The CeO2 nanowires were synthesized by hydrothermal route.•The sensor based on CeO2 film shows a high performance in detecting H2S gas.•The sensor’s detection limit towards H2S gas is as low as 50 ppb.•The sensor shows a short response/recovery time (24 s and 15 s, respectively for 50 ppb H2S).
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