Oxygen vacancy engineering of Bi2O3/Bi2O2CO3 heterojunctions: Implications of the interfacial charge transfer, NO adsorption and removal

Efficient enrichment of targeted gaseous pollutants and fast diffusion rates of charge carriers are essential for the photocatalytic removal of nitric oxides at ambient concentration levels. Here we demonstrate that the construction of nano-structured Bi2O3/Bi2O2CO3 heterojunctions with oxygen vacancies, increasing the photocatalytic NO removal activity, durability and selectivity for final products nitrate formation. Combining the experimental and density-functional theory calculations, it was elucidated that the presence of surface oxygen vacancies not only work as adsorption sites of low concentration NO, but also offer an intimate and integrated structure between surface defects and the light-harvesting heterojunctions, which can facilitate solar energy conversion and charge carrier transfer (more than 2 times). Control experiments with pristine Bi2O3/Bi2O2CO3 also confirmed the crucial role of surface oxygen vacancies on the improvement of NO adsorption and removal ability during the photocatalytic degradation process. We explain the enhanced removal of NO through the synergistic effect of oxygen vacancy and heterojunction, which not only guaranteed the generation of more center dot OH radicals, but also provided another route to produce hydrogen peroxide. Our findings may provide an opportunity to develop a promising catalyst for air pollution control

Synthesis of a Bi2O2CO3/ZnFe2O4 heterojunction with enhanced photocatalytic activity for visible light irradiation-induced NO removal

Although bismuth subcarbonate (Bi2O2CO3), a member of the Aurivillius-phase oxide family, is a promising photocatalyst for the removal of gaseous NO at parts-per-billion level, the large band gap of this material restricts its applications to the UV light region. The above problem can be mitigated by heterojunction fabrication, which not only broadens the light absorbance range, but also inhibits the recombination of photogenerated charge carriers. Herein, we implement this strategy to fabricate a novel Bi2O2CO3/ZnFe2O4 photocatalyst for NO removal under visible light irradiation and authenticate the formation of the above p-n heterojunction using an array of analytical techniques. Notably, the above composite showed activity superior to those of its individual constituents, and the underlying mechanisms of this activity enhancement were probed by density functional theory calculations and photocurrent measurements. Elevated electron/hole separation efficiency caused by the presence of an internal electric field at the Bi2O2CO3/ZnFe2O4 interface was identified as the main reason of the increased photocatalytic activity, with the main active species were determined as center dot O-2(-) and center dot OH by electron spin resonance spectroscopy. Finally, cytotoxicity testing proved the good biocompatibility of Bi2O2CO3/ZnFe2O4. Thus, this work presents deep insights into the preparation and use of a green p-n heterojunction catalyst in various applications

Liraglutide-induced reduction of myocardial ischemiareperfusion injury in rats via ERK1/2 signaling pathway

Purpose: To investigate the protective effect of liraglutide on myocardial ischemia reperfusion (I/R) injury and its molecular mechanism.Methods: Ischemia reperfusion model male Sprague-Dawley (SD) rats were randomly divided into negative control group, I/R group (saline), liraglutide group (liraglutide) and PD group (liraglutide + PD98059). The weight of myocardium in ischemic and infarction areas of the heart, myocardial injury biomarker, oxidative stress, as well as expressions of mRNA molecules of apoptosis were determined.Results: The myocardial mass of ischemic and infarcted areas of the heart (relative to left ventricular mass) of I/R group were significantly higher (p ˂ 0.05) than those of negative control group, but significantly lower in liraglutide group than in I/R group (p > 0.05). However, the parameters were significantly higher in PD group than in liraglutide group (p ˂ 0.05). CK, CK-MB and LDH activities, as well as levels of cTnI and cTnT in I/R group were significantly higher (p ˂ 0.05) than those of negative control group. However, the parameters were significantly lower (p ˂ 0.05) in liraglutide group than in I/R group, but higher in PD group (p ˂ 0.05) than in liraglutide group. Serum SOD, GSH-Px, CAT activities and tBcl-2 mRNA expression were significantly lower in I/R group than those of negative control group (p ˂ 0.001), while those PD group were significantly lower than those of liraglutide group (p ˂ 0.001).Conclusion: Liraglutide alleviates myocardial ischemia-reperfusion injury and inhibits oxidative stress and apoptosis via ERK1/2 signaling pathway in rats, but further studies are required to ascertain the clinical efficacy and safety of the compound.Keywords: Ischemia-reperfusion injury, Liraglutide, ERK1/2 signal pathway, Oxidative stress, Apoptosi

Determinants of personal exposure to fine particulate matter (PM2.5) adult subjects in Hong Kong

Personal monitoring for fine particulate matter (PM2.5) was conducted for adults (48 subjects, 18-63 years of age) in Hong Kong during the summer and winter of 2014-2015. All filters were analyzed for PM2.5 mass and constituents (including carbonaceous aerosols, water-soluble ions, and elements). We found that season (p = 0.02) and occupation (p < 0.001) were significant factors affecting the strength of the personal-ambient PM2.5 associations. We applied mixed-effects models to investigate the determinants of personal exposure to PM2.5 mass and constituents, along with within- and between-individual variance components. Ambient PM2.5 was the dominant predictor of (R-2 = 0.12-0.59, p < 0.01) and the largest contributor (>37.3%) to personal exposures for PM2.5 mass and most components. For all subjects, a one-unit (2.72 mu g/m(3)) increase in ambient PM2.5 was associated with a 0.75 mu g/m(3) (95% CI: 0.59-0.94 mu g/m(3)) increase in personal PM2.5 exposure. The adjusted mixed-effects models included information extracted from individual's activity diaries as covariates. The results showed that season, occupation, time indoors at home, in transit, and cleaning were significant determinants for PM2.5 components in personal exposure (R-beta(2) = 0.06-0.63, p < 0.05), contributing to 3.0-70.4% of the variability. For onehour extra time spent at home, in transit; and cleaning an average increase of 1.7-3.6% (ammonium, sulfate, nitrate, sulfur), 2.7-12.3% (elemental carbon, ammonium, titanium, iron), and 8.7-19.4% (ammonium, magnesium ions, vanadium) in components of personal PM2.5 were observed, respectively. In this research, the within-individual variance component dominated the total variability for all investigated exposure data except PM2.5 and EC. Results from this study indicate that performing long-term personal monitoring is needed for examining the associations of mass and constituents of personal PM2.5 with health outcomes in epidemiological studies by describing the impacts of individual-specific data on personal exposures. (C) 2018 Elsevier B.V. All rights reserved

Multicolor Photometry Study of the Galaxy Cluster A2589: Dynamics, Luminosity Function and Star Formation History

In this paper we present a multicolor photometry for A2589 ($z=0.0414$) with 15 intermediate bands in the Beijing-Arizona-Taiwan-Connecticut (BATC) system which covers an optical wavelength range from 3000 \AA\ to 10000 \AA. The spectral energy distributions (SEDs) for more than 5000 sources are achieved down to {\it V} $\sim$ 20 mag in about 1 deg$^{2}$ field. A2589 has been also covered by the Sloan Digital Sky Survey (SDSS) in photometric mode only. A cross-identification of the BATC-detected galaxies with the SDSS photometric catalog achieves 1199 galaxies brighter than $i=19.5$ mag, among which 68 member galaxies with known spectroscopic redshifts are found. After combining the SDSS five-band photometric data and the BATC SEDs, the technique of photometric redshift is applied to these galaxies for selecting faint member galaxies. The color-magnitude relation is taken as a further restriction of early-type cluster galaxies. As a result, 106 galaxies are newly selected as member galaxies. Spatial distribution of member galaxies shows a north-south elongation which agrees with the X-ray brightness profile and the orientation of central cD galaxy, NGC 7647. No substructures are detected on the basis of positions and radial velocities of cluster galaxies, indicating that A2589 is a well-relaxed system. The luminosity function of A2589 exhibits a peak at $M_{R} \sim -20$ mag and a dip at $M_{R} \sim -19$ mag. The low-density outer regions are the preferred habitat of faint galaxies. With the evolutionary population synthesis model, PEGASE, the environmental effect on the star formation properties for 68 spectroscopically confirmed member galaxies is studied. The outlier faint galaxies tend to have longer time scales of star formation, shorter mean stellar ages, and lower metallicities of interstellar medium, which can be interpreted in the context of hierarchical cosmological scenario.Comment: 2011 Accepted to A

An immune-responsive Serpin regulates the melanization cascade in Drosophila

In arthropods, the melanization reaction is associated with multiple host defense mechanisms leading to the sequestration and killing of invading microorganisms. Arthropod melanization is controlled by a cascade of serine proteases that ultimately activates the enzyme prophenoloxidase (PPO), which, in turn, catalyzes the synthesis of melanin. Here we report the biochemical and genetic characterization of a Drosophila serine protease inhibitor protein, Serpin-27A, which regulates the melanization cascade through the specific inhibition of the terminal protease prophenoloxidase-activating enzyme. Our data demonstrate that Serpin-27A is required to restrict the phenoloxidase activity to the site of injury or infection, preventing the insect from excessive melanization