Ni–Fe and Ni–Fe–Co mixed-metal oxide (MMO) films were investigated as electrocatalysts for the oxygen evolution reaction (OER) in 0.1 M KOH. In an effort to optimize MMO morphology, aniline was used ...as a capping agent to produce high-surface-area Ni–Fe–Co films on Raney nickel supports. This catalyst exhibits enhanced mass activity in comparison to the Ni–Fe OER electrocatalysts reported to date. Cyclic voltammetry shows changes in the potential of the Ni2+/3+ transitions in Fe- or Co-containing MMO films. In situ X-ray absorption spectroscopy (XAS) analysis confirms that Fe acts to stabilize Ni in the 2+ oxidation state, while Co facilitates oxidation to the 3+ state. The results of this study support the recent claims that Fe (not Ni) is the OER active site. The OER enhancement of the ternary Ni–Fe–Co catalyst results from two effects: (1) the charge-transfer effects of Co result in the formation of the conductive NiIIIOOH phase at lower overpotential, thus activating the Fe sites which are otherwise inaccessible to electron transfer in the nonconductive NiII(OH)2 host lattice, and (2) XAS analysis shows that the presence of Co effectively “shrinks” the Ni and Fe local geometry, likely resulting in an optimized Fe–OH/OOH bond strength. In addition, analysis of heat-treatment effects indicates that calcination at 400 °C improves the OER activity of Ni–Fe–Co but deactivates Ni–Fe. Annealing studies under argon show that MMO surfaces with a hydrated Ni(OH)2 phase and a crystalline NiO phase exhibit nearly identical OER activities. Finally, the morphology of the MMO catalyst film on Raney Ni support provides excellent catalyst dispersion and should result in high active-site utilization for use in technologically relevant gas-diffusion electrodes.
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Realization of the hydrogen economy relies on effective hydrogen production, storage, and utilization. The slow kinetics of hydrogen evolution and oxidation reaction (HER/HOR) in alkaline media ...limits many practical applications involving hydrogen generation and utilization, and how to overcome this fundamental limitation remains debatable. Here we present a kinetic study of the HOR on representative catalytic systems in alkaline media. Electrochemical measurements show that the HOR rate of Pt‐Ru/C and Ru/C systems is decoupled to their hydrogen binding energy (HBE), challenging the current prevailing HBE mechanism. The alternative bifunctional mechanism is verified by combined electrochemical and in situ spectroscopic data, which provide convincing evidence for the presence of hydroxy groups on surface Ru sites in the HOR potential region and its key role in promoting the rate‐determining Volmer step. The conclusion presents important references for design and selection of HOR catalysts.
Bifunctional mechanism: Experimental evidence for hydroxy groups adsorbed onto Ru surface sites at the hydrogen oxidation reaction (HOR) potential region supports the bifunctional mechanism for the HOR kinetics of Pt‐Ru/C and Ru/C catalysts in alkaline media. The result presents important references for the design and selection of HOR catalysts.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Despite recent progress in developing active and durable oxygen reduction catalysts with reduced Pt content, lack of elegant bottom-up synthesis procedures with knowledge over the control of atomic ...arrangement and morphology of the Pt–alloy catalysts still hinders fuel cell commercialization. To follow a less empirical synthesis path for improved Pt-based catalysts, it is essential to correlate catalytic performance to properties that can be easily controlled and measured experimentally. Herein, using Pt–Co alloy nanoparticles (NPs) with varying atomic composition as an example, we show that the atomic distribution of Pt-based bimetallic NPs under operating conditions is strongly dependent on the initial atomic ratio by employing microscopic and in situ spectroscopic techniques. The Pt x Co/C NPs with high Co content possess a Co concentration gradient such that Co is concentrated in the core and gradually depletes in the near-surface region, whereas the Pt x Co/C NPs with low Co content possess a relatively uniform distribution of Co with low Co population in the near-surface region. Despite their different atomic structure, the oxygen reduction reaction (ORR) activity of Pt x Co/C and Pt/C NPs is linearly related to the bulk average Pt–Pt bond length (R Pt–Pt). The R Pt–Pt is further shown to contract linearly with the increase in Co/Pt composition. These linear correlations together demonstrate that (i) the improved ORR activity of Pt x Co/C NPs over pure Pt NPs originates predominantly from the compressive strain and (ii) the R Pt–Pt is a valid strain descriptor that bridges the activity and atomic composition of Pt-based bimetallic NPs.
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Results have been conflicting whether long-term ambient hydrogen sulfide (H2S) affects lung function or is a risk factor for asthma or chronic obstructive pulmonary disease (COPD). Rotorua city, New ...Zealand, has the world's largest population exposed to ambient H2S-from geothermal sources.
We investigated associations of H2S with lung function, COPD and asthma in this population.
1,204 of 1,639 study participants, aged 18-65 years during 2008-2010, provided satisfactory spirometry results. Residences, workplaces and schools over the last 30 years were geocoded. Exposures were estimated from data collected by summer and winter H2S monitoring networks across Rotorua. Four metrics for H2S exposure, representing both current and long-term (last 30 years) exposure, and also time-weighted average and peak exposures, were calculated. Departures from expected values for pre-bronchodilator lung function, calculated from prediction equations, were outcomes for linear regression models using quartiles of the H2S exposure metrics. Separate models examined participants with and without evidence of asthma or COPD, and never- and ever-smokers. Logistic regression was used to investigate associations of COPD (a post-bronchodilator FEV1/FVC < 70% of expected) and asthma (doctor-diagnosed or by FEV1 response to bronchodilator) with H2S exposure quartiles.
None of the exposure metrics produced evidence of lung function decrement. The logistic regression analysis showed no evidence that long-term H2S exposure at Rotorua levels was associated with either increased COPD or asthma risk. Some results suggested that recent ambient H2S exposures were beneficially associated with lung function parameters.
The study found no evidence of reductions in lung function, or increased risk of COPD or asthma, from recent or long-term H2S exposure at the relatively high ambient concentrations found in Rotorua. Suggestions of improved lung function associated with recent ambient H2S exposures require confirmation in other studies.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
•We estimate the impact of a learning community on first-year college retention at a four-year public research university using a randomized control trial.•Intent-to-treat and ...local-average-treatment-effect estimates reveal no discernable programmatic effects.•Observational approaches find impacts that are positive, large and statistically significant.•Decomposing the observational estimates reveal that non-random selection into the experimental sample accounts for the major difference in the two estimates.•This exercise cautions against generalizing the RCT result for populations outside the experiment.
In this paper, we estimate the impact of a learning community on first-year college retention at a four-year public research university using a randomized control trial (RCT) for those students who opt into the experiment. Intent-to-treat and local-average-treatment-effect estimates reveal no discernable programmatic effects. We also generate estimates of program impact using observational techniques and find estimated impacts that are positive, large and statistically significant. We explore a variety of selection processes to better understand the differences between the RCT and observational estimates and to reflect on the generalizability of the RCT results for various other populations of interest. Non-random selection into the experimental sample accounts for the major difference in the two estimates and also cautions against generalizing the RCT result for populations outside the experiment.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Kerosene has been an important household fuel since the mid-19th century. In developed countries its use has greatly declined because of electrification. However, in developing countries, kerosene ...use for cooking and lighting remains widespread. This review focuses on household kerosene uses, mainly in developing countries, their associated emissions, and their hazards. Kerosene is often advocated as a cleaner alternative to solid fuels, biomass and coal, for cooking, and kerosene lamps are frequently used when electricity is unavailable. Globally, an estimated 500 million households still use fuels, particularly kerosene, for lighting. However, there are few studies, study designs and quality are varied, and results are inconsistent. Well-documented kerosene hazards are poisonings, fires, and explosions. Less investigated are exposures to and risks from kerosene's combustion products. Some kerosene-using devices emit substantial amounts of fine particulates, carbon monoxide (CO), nitric oxides (NO
x
), and sulfur dioxide (SO
2
). Studies of kerosene used for cooking or lighting provide some evidence that emissions may impair lung function and increase infectious illness (including tuberculosis), asthma, and cancer risks. However, there are few study designs, quality is varied, and results are inconsistent. Considering the widespread use in the developing world of kerosene, the scarcity of adequate epidemiologic investigations, the potential for harm, and the implications for national energy policies, researchers are strongly encouraged to consider collecting data on household kerosene uses in studies of health in developing countries. Given the potential risks of kerosene, policymakers may consider alternatives to kerosene subsidies, such as shifting support to cleaner technologies for lighting and cooking.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
A third of the world's population uses solid fuel derived from plant material (biomass) or coal for cooking, heating, or lighting. These fuels are smoky, often used in an open fire or simple stove ...with incomplete combustion, and result in a large amount of household air pollution when smoke is poorly vented. Air pollution is the biggest environmental cause of death worldwide, with household air pollution accounting for about 3·5-4 million deaths every year. Women and children living in severe poverty have the greatest exposures to household air pollution. In this Commission, we review evidence for the association between household air pollution and respiratory infections, respiratory tract cancers, and chronic lung diseases. Respiratory infections (comprising both upper and lower respiratory tract infections with viruses, bacteria, and mycobacteria) have all been associated with exposure to household air pollution. Respiratory tract cancers, including both nasopharyngeal cancer and lung cancer, are strongly associated with pollution from coal burning and further data are needed about other solid fuels. Chronic lung diseases, including chronic obstructive pulmonary disease and bronchiectasis in women, are associated with solid fuel use for cooking, and the damaging effects of exposure to household air pollution in early life on lung development are yet to be fully described. We also review appropriate ways to measure exposure to household air pollution, as well as study design issues and potential effective interventions to prevent these disease burdens. Measurement of household air pollution needs individual, rather than fixed in place, monitoring because exposure varies by age, gender, location, and household role. Women and children are particularly susceptible to the toxic effects of pollution and are exposed to the highest concentrations. Interventions should target these high-risk groups and be of sufficient quality to make the air clean. To make clean energy available to all people is the long-term goal, with an intermediate solution being to make available energy that is clean enough to have a health impact.
We report a Ni–Cr/C electrocatalyst with unprecedented mass-activity for the hydrogen evolution reaction (HER) in alkaline electrolyte. The HER kinetics of numerous binary and ternary Ni-alloys and ...composite Ni/metal-oxide/C samples were evaluated in aqueous 0.1 M KOH electrolyte. The highest HER mass-activity was observed for Ni–Cr materials which exhibit metallic Ni as well as NiO x and Cr2O3 phases as determined by X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) analysis. The onset of the HER is significantly improved compared to numerous binary and ternary Ni-alloys, including Ni–Mo materials. It is likely that at adjacent Ni/NiO x sites, the oxide acts as a sink for OHads, while the metallic Ni acts as a sink for the Hads intermediate of the HER, thus minimizing the high activation energy of hydrogen evolution via water reduction. This is confirmed by in situ XAS studies that show that the synergistic HER enhancement is due to NiO x content and that the Cr2O3 appears to stabilize the composite NiO x component under HER conditions (where NiO x would typically be reduced to metallic Ni0). Furthermore, in contrast to Pt, the Ni(O x )/Cr2O3 catalyst appears resistant to poisoning by the anion exchange ionomer (AEI), a serious consideration when applied to an anionic polymer electrolyte interface. Furthermore, we report a detailed model of the double layer interface which helps explain the observed ensemble effect in the presence of AEI.
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Bovine leukemia virus (BLV) infection is widespread in cattle globally and is present in marketed beef and dairy products. Human infection with BLV has been reported in breast and lung cancer tissues ...and was significantly associated with breast cancer in 3 case-control studies. The purpose of this current research was to determine if BLV is present in human blood cells and if antibodies to BLV are related to blood cell infection.
Standard liquid PCR and Sanger DNA sequencing were used to test for BLV in buffy coat cells (leukocytes and platelets) of blood specimens from 95 self-selected female subjects. Enzyme-linked immunosorbent assay (ELISA) for IgG, IgM, and IgA was used to detect antibodies to BLV in the plasma of the corresponding blood samples.
BLV DNA was detected in the buffy coat cells of blood in 33/95 (38%) of the subjects by PCR and DNA sequencing. IgG antibodies were detected in 30/95(32%), IgM in 55/95(58%), and IgA in 30/95(32%) of the subjects. There was no significant correlation between presence of the antibodies and presence of BLV DNA.
This first report of BLV in human blood raises the question of whether infection of leukocytes could conceivably lead to leukemia as it does in infected cattle. Also, system wide circulation of infected blood cells could facilitate BLV transit to various internal tissues/organs with potential for their infection and subsequent development of cancer. The most likely route of BLV transmission to humans would be zoonotic, as a foodborne infection. Although eradicated from cattle in some countries, BLV still has a high rate of infection in the Americas, the Middle East, and parts of Europe and Asia. This report of BLV in the blood layer containing human leukocytes/platelets adds important information which could be useful to elucidate possible routes of transmission of BLV to humans and to prevent further human infection.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Household air pollution generated from solid fuel use for cooking is one of the leading risk factors for ill-health globally. Deployment of advanced cookstoves to reduce emissions has been a major ...focus of intervention efforts. However, household usage of these stoves and resulting changes in usage of traditional polluting stoves is not well characterized. In Palwal District, Haryana, India, we carried out an intervention utilizing the Philips HD4012 fan-assisted stove, one of the cleanest biomass stoves available. We placed small, unobtrusive data-logging iButton thermometers on both the traditional and Philips stoves to collect continuous data on use patterns in 200 homes over 60 weeks. Intervention stove usage declined steadily over time and stabilized after approximately 200 days; use of the traditional stove remained relatively constant. We additionally evaluated how well short-duration usage measures predicted long-term use. Measuring usage over time of both traditional and intervention stoves provides better understanding of cooking behaviors and can lead to more precise quantification of potential exposure reductions and consequent health benefits attributable to interventions.
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