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The sluggish oxygen reduction reaction (ORR) on the cathode severely limits the energy conversion efficiency of microbial fuel cells (MFCs). In this study, cobalt and nitrogen co-doped ordered mesoporous carbon (Cox-N-OMC) was prepared by heat-treating a mixture of cobalt nitrate, melamine and ordered mesoporous carbon (OMC). The addition of cobalt nitrate remarkably improved the ORR reactivity, compared to the nitrogen-doped OMC catalyst. By optimizing the dosage of cobalt nitrate (x = 0.6, 0.8 and 1.0 g), the Co0.8-N-OMC catalyst displayed excellent ORR catalytic performances in neutral media with the onset potential of 0.79 V (vs. RHE), half-wave potential of 0.59 V and limiting current density of 5.43 mA/cm2, which was comparable to the commercial Pt/C catalyst (0.86 V, 0.60 V and 4.76 mA/cm2). The high activity of Co0.8-N-OMC catalyst was attributed to the high active surface area, higher total nitrogen amount, and higher relative distribution of graphitic nitrogen and pyrrolic nitrogen species. Furthermore, single chamber microbial fuel cell (SCMFC) with Co0.8-N-OMC cathode exhibited the highest power density of 389 ± 24 mW/m2, chemical oxygen demand (COD) removal of 81.1 ± 2.2% and coulombic efficiency (CE) of 17.2 ± 2.5%. On the other hand, in the Co1.0-N-OMC catalyst, increasing the cobalt dosage from 0.8 to 1.0 g resulted in more oxidized-N species, and the reduced power generation in SCMFC (360 ± 8 mW/m2). The power generated by these catalysts and results of electrochemical evaluation were strongly correlated with the total nitrogen contents on the catalyst surface. This study demonstrated the feasibility of optimizing the dosage of metal to enhance wastewater treatment capacity.

Many studies, including the HYENA and the DEBATS studies, showed a significant association between aircraft noise exposure and the risk of hypertension. Few studies have considered aircraft noise annoyance and noise sensitivity as factors of interest, especially in relation to hypertension risk, or as mediating or modifying factors. The present study aims 1) to investigate the risk of hypertension in relation to aircraft noise annoyance or noise sensitivity; and 2) to examine the role of modifier or mediator of these two factors in the association between aircraft noise levels and the risk of hypertension.

This study included 6,105 residents of ten European airports from the HYENA and DEBATS studies. Information on aircraft noise annoyance, noise sensitivity, and demographic, socioeconomic and lifestyle factors was collected during an interview performed at home. Participants were classified as hypertensive if they had either blood pressure levels above the WHO cut-off points or physician-diagnosed hypertlable studies to date suggesting adverse health effects associated with aircraft noise annoyance and noise sensitivity. The findings also indicate possible modifier effects of aircraft noise annoyance and noise sensitivity in the relationship between aircraft noise levels and the risk of hypertension. see more However, further investigations are needed to better understand this role using specific methodology and tools related to mediation analysis and causal inference.Health and safety hazards associated with the redevelopment of contaminated sites can be complex and pose considerable risks. A systematic literature review was conducted on risk assessment tools for contaminated sites. These tools have been identified from searching through leading academic databases and other professional sources. For each of the identified tools the relevant risk assessment stages, harm type, hazard category, receptor type and pathways are reported. Findings reveal that despite growing interest in the development of risk assessment tools, there are persistent knowledge gaps identified in this study, which serve as a basis for future research direction to where more advanced practical tools could be invented. For instance, it is evidenced there is a shortfall in practical tools available to contaminated site assessors conducting investigations at the preliminary risk assessment stage. Addressing this opening can benefit the planning process, coordinated between relevant stakeholders and, moreover, reduce uncertainty in the decision-making of contaminated site developers.Studying weekend-weekday variation in ground-level ozone (O3) allows one to better understand O3 formation conditions, with a potential for developing effective strategies for O3 control. Reducing inappropriately the O3 precursors emissions can either produce no reduction or increase surface O3 concentrations. This paper analyzes the weekend-weekday differences of O3 at 300 rural and 808 urban background stations worldwide from 2005 to 2014, in order to investigate the O3 weekend effect over time and assess the effectiveness of the precursors emissions control policies for reducing O3 levels. Data were analyzed with the non-parametric Mann-Kendall test and Theil-Sen estimator. Rural sites typically did not experience a weekend-weekday effect. In all urban stations, the mean O3 concentration on the weekend was 12% higher than on weekdays. Between 2005 and 2014, the annual mean of daily O3 concentrations increased at 74% of urban sites worldwide (+ 0.41 ppb year-1) and decreased in the United Kingdom (- 0.18 ppb year-1). Over this time period, emissions of O3 precursors declined significantly. However, a greater decline in nitrogen oxides (NOx) emissions caused an increase in Volatile Organic Compounds (VOCs) to NOx ratios leading to O3 formation. In France, South Korea and the United Kingdom, most urban stations showed a significant upward trend (+ 1.15% per year) for O3 weekend effect. Conversely, in Canada, Germany, Japan, Italy and the United States, the O3 weekend effect showed a significant downward trend (- 0.26% per year). Further or inappropriate control of anthropogenic emissions in Canada, Southern Europe, Japan, South Korea and the United States might result in increased daily O3 levels in urban areas.This study draws the link between COVID-19 and air pollution (ground ozone O3) from February 29, 2020 to July 10, 2020 in the top 10 affected States of the US. Utilizing quantile-on-quantile (QQ) estimation technique, we examine in what manner the quantiles of COVID-19 affect the quantiles of air pollution and vice versa. The primary findings confirm overall dependence between COVID-19 and air pollution. Empirical results exhibit a strong negative effect of COVID-19 on air pollution in New York, Texas, Illinois, Massachusetts, and Pennsylvania; especially at medium to higher quantiles, while New Jersey, Illinois, Arizona, and Georgia show strong negative effect mainly at lower quantiles. Contrarily, COVID-19 positively affects air pollution in Pennsylvania at extreme lower quantiles. On the other side, air pollution predominantly caused to increase in the intensity of COVID-19 cases across all states except lower quantiles of Massachusetts, and extreme higher quantiles of Arizona and New Jersey, where this effect becomes less pronounced or negative.