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The MnII(HCO3–)–H2O2 (MnII-BAP) system shows high reactivity toward oxidation of electron-rich organic substrates; however, the predominant oxidizing species and its formation pathways involved in ...

Bi2+xWO6 is a cost-effective and environmentally friendly photocatalyst that shows high reactivity in the oxidation of various contaminants under visible light. However, under alkaline conditions, the reactive oxidative species in the Bi2+xWO6 system are still not clear yet. In this study, it is observed that the oxidation rates of As(III) increase with increasing pH values in the Bi2.15WO6 system. Photoluminescence and the Mott–Schottky analyses confirm that OH− promotes the separation and transfer of photogenerated electron–hole pairs over Bi2.15WO6, thus facilitating the oxidation of As(III). Electron spin resonance spectra analysis and quenching experiments rule out contributions of •OH, O2˙−, 1O2 and superoxo species to As(III) oxidation and indicate that surface –OOH and/or H2O2 are indeed the predominant species under alkaline conditions. The improved production of H2O2 by H-donors such as glucose and phenol, as well as the UV-vis diffuse reflectance and Raman analyses, further confirms the formation of surface –OOH on Bi2.15WO6 under alkaline conditions. In the dark, the significant higher oxidation rate of As(III) by H2O2–Bi2.15WO6 than that by H2O2 alone reveals that surface −OOH, instead of H2O2, plays an important role in As(III) oxidation. This study enriches our understanding of the diversity of reactive oxygen species (ROS) in the Bi2.15WO6 system and gives new insight into the mechanism involved in the oxidation of As(III) under alkaline conditions.

Bi2+xWO6 is a cost-effective and environmentally friendly photocatalyst that shows high reactivity in the oxidation of various contaminants under visible light. However, under alkaline conditions, the reactive oxidative species in the Bi2+xWO6 system are still not clear yet. In this study, it is observed that the oxidation rates of As(iii) increase with increasing pH values in the Bi2.15WO6 system. Photoluminescence and the Mott-Schottky analyses confirm that OH- promotes the separation and transfer of photogenerated electron-hole pairs over Bi2.15WO6, thus facilitating the oxidation of As(iii). Electron spin resonance spectra analysis and quenching experiments rule out contributions of •OH, O2˙-, 1O2 and superoxo species to As(iii) oxidation and indicate that surface -OOH and/or H2O2 are indeed the predominant species under alkaline conditions. The improved production of H2O2 by H-donors such as glucose and phenol, as well as the UV-vis diffuse reflectance and Raman analyses, further confirms the formation of surface -OOH on Bi2.15WO6 under alkaline conditions. In the dark, the significant higher oxidation rate of As(iii) by H2O2-Bi2.15WO6 than that by H2O2 alone reveals that surface -OOH, instead of H2O2, plays an important role in As(iii) oxidation. This study enriches our understanding of the diversity of reactive oxygen species (ROS) in the Bi2.15WO6 system and gives new insight into the mechanism involved in the oxidation of As(iii) under alkaline conditions.

The Mn

Although the oxidation processes mediated by persulfate (PS) and peroxymonosulfate (PMS) attract more attention in the degradation of various recalcitrant contaminants, the high concentrations of oxidants required for the low concentrations of contaminants always limit their large-scale applications. In this work, aniline can be effectively oxidized by CuO and PS under pH-neutral and alkaline conditions. The increased observed rate constant (kobs) values with increasing pHs indicate that the oxidation of aniline is facilitated by solution OH−. Meanwhile, the low ratios between the removed PS and aniline (1.19 at pH 7.0 and 1.68 at pH 12.0) indicate the high catalytic oxidation efficacy of the CuO-PS system. The insignificant contributions of SO4 −, OH, 1O2 and O2 − to aniline oxidation in quenching experiments and EPR analysis suggest that PS is likely activated on the surface of CuO via the non-radical pathway. The presence of carbon-centered radicals (CCRs), as well as UV and GC MS analysis, indicates the important intermediates of PhNH2 + and PhNH radicals during the oxidation process, revealing that separate transfer of an electron from aniline to the activated PS, followed by subsequent abstraction of a H+ by OH− to form PhNH are two important steps in the oxidation process. Further coupling of PhNH radicals results in the formation of insoluble polyaniline polymers at pHs 7.0 and 12.0. The high thermal stability and ideal pseudo-capacitive properties of the insoluble products indicate that the polyaniline produced from aniline wastewater can be used for high-temperature-resistant materials or capacitors. This study provides an efficient alternative to turn aniline waste to polyaniline polymers.

Turning heterocyclic contaminants into polymers from industrial wastewater is a promising method that opens a new door for feasible and cost-effective treatment for aromatic wastewater. In this study, CuO shows the high reactivity in the catalytic oxidation of thiophene by persulfate (PS) under pH-neutral condition, and the observed rate constant (kobs) in the PS-CuO system is about 10 times of that in the PS-alone system at pH 7.0. The linear relationship between the consumed PS and the removed thiophene reveals that a complete removal of 1.0 mM thiophene from solution requires 1.11 mM PS in the PS-CuO system, indicating that thiophene has not been completely mineralized into CO2 and H2O. Quenching experiments and EPR analysis rule out contributions of O2•− and 1O2 to thiophene oxidation, and suggest that although both SO4•− and •OH contribute to thiophene oxidation to some extent, they are not the primary oxidants in the PS-CuO system at pH 7.0. Meanwhile, the presence of thiophene radical cation indicates that electron abstraction from thiophene is an important pathway in the oxidation. The produced thiophene radical cations are then polymerized into polymers. Solid characterizations further confirm that polythiophene S,S-dioxide is the primary oxidation product. The electrochemical analysis indicates that the produced polythiophene S,S-dioxide polymers show pseudocapacitive characteristics and can be used for capacitors.

Pyrite is an extensively-distributed mineral that catalyzes oxidation of As(III) to As(V) by dissolved oxygen (DO) in natural environments; however, the catalytic mechanism of pyrite under alkaline conditions is still not clear. In this study, we observed increased oxidation rates of soluble As(III) with increasing pHs under alkaline conditions (7.5-11.0). ESR analysis and quenching experiments rule out contributions of •OH, O2•- and 1O2 to As(III) oxidation, and indicate that Fe(III)-OOH and/or H2O2 are indeed the primary oxidative species at pHs 9.0 and 11.0, and Fe(IV)=O also contributes at pH 11.0. Selective oxidation of a series of organic substrates to the corresponding oxidation products confirms the presence of Fe(III)-OOH and/or Fe(IV)=O in the pyrite system in alkaline solutions or organic solvents. Although the addition of glucose apparently increases the production of H2O2 at pHs 9.0 and 11.0, such an increase does not apparently accelerate the oxidation rate of As(III), implying that H2O2 is not the predominant species in the oxidation of As(III). This study provides new insight into the oxidative species in the pyrite-DO system under alkaline conditions.

Examination stress occurs so frequently in the lives of students. The neural mechanisms of attentional bias induced by examination stress in test-anxious individuals remain unclear. Accordingly, we investigated the attentional bias toward test-related threatening words in selected high and low test-anxious participants under the stress of final examinations by using an event-related potential (ERP) technique. A classic dot-probe paradigm was adopted with a test-related/test-unrelated threatening word and a neutral word pair as cues. Results showed attention bias and enhanced N200 amplitude toward test-related threat in high test-anxious individuals, whereas avoidance of test-related threat and decreased N200 amplitude were shown in low test-anxious individuals. Additionally, ERP data revealed the relatively enhanced LPP amplitude in low test-anxious participants compared with that in high test-anxious participants. No attentional bias toward test-unrelated threat was found. In conclusion, examination stress resulted in attentional bias and functional perturbations of a brain circuitry that reacted rapidly to test-related threat in high test-anxious individuals.

In order to improve the flexibility of computer protection on relay protection and to simplify the development process, this paper presents a new method which a programmable logic is applied to relay protection in form of software and hardware platform. The method can better satisfy the needs of relay protection. Aiming at the shortage of traditional relay protection deceive, this paper mainly discuss how to realize the modularization of the new hardware and software platform and to make the theoretical analysis about logic hardware and software platform.

Introgression of exotic maize (Zea mays L.) germplasm is an effective approach to broadening the genetic base of Chinese germplasm. America is the center of maize origin and germplasm diversity. By analyzing general combining ability effects and heterosis responses among maize populations from the U.S., International Maize and Wheat Improvement Center (CIMMYT), and Brazil studied by different authors, 24 elite maize populations from America region, including eight U.S. populations, eight CIMMYT populations, and eight Brazilian populations, were identified as having high potential in China. Based on adaptation improvement, we suggest to introgress BSSS(R)C10, BS10(FR)C14, BS13(S)C9, BSK(HI)C8 Syn 3, BR106, Pop44(C8), and Pop45(C3) into Chinese heterotic group A, and introgress BS11(FR)C14, BS16(S)C3 Syn 2, BS29(R)C3, BSCB1(R)C14, BR105, and Pop42(C4) into Chinese heterotic group B by forming semi-exotic populations or pools, respectively, in order to broaden the Chinese germplasm base.