Construction of a macromolecular structural model of Chinese lignite and analysis of its low-temperature oxidation behavior

The aim of this paper is to analyze the change in the active structure of lignite during the process of lowtemperature oxidation by constructing a molecular structure model for lignite. Using quantum computation combined with experimental results of proximate analysis, ultimate analysis, Fourier transform infrared spectroscopy(FTIR) and X-ray photoelectron spectroscopy(XPS), a structural model for the large molecular structure was constructed. By analyzing the bond lengths in the model molecule, the evolution law for the active structure of lignite was predicted for the process of low-temperature oxidation. In low-temperature oxidation,alkanes and hydroxyls are the primary active structures observed in lignite, though ether may also react. These active functional groups react with oxygen to release heat, thereby speeding up the reaction between coal and oxygen. Finally, the content of various functional groups in the process of lignite low-temperature oxidation was analyzed by infrared analysis, and the accuracy of the model was verified.

Hydrogen Therapy Reduces Oxidative Stress-associated Risks Following Acute and Chronic Exposure to High-altitude Environment

Low pressure,low oxygen concentration,and intense ultraviolet（UV）radiation in high-altitude environments,can cause oxidative stress which can trigger mountain sickness.A recent study demonstrated that hydrogen gas with a good permeability in biological membranes can treat various disorders by exerting its selective anti-oxidation and anti-inflammatory effects,indicating that hydrogen therapy plays a role in scavenging free radicals and in balancing oxidation and anti-oxidation systems of ceils. Therefore, we hypothesize that inhaling low-dose hydrogen or drinking hydrogen-saturated water is a novel and simple method to prevent and treat oxidative stress injury caused by low pressure, low oxygen concentration and intense UV radiation in plateaus, thus reducing the risk of mountain sickness.

Ozonation of o-phenylenediamine in the presence of hydrogen peroxide by high-gravity technology

The study herein investigated the effectiveness of simultaneous use of ozone and hydrogen peroxide(O_3/H_2O_2 process) to degrade o-phenylenediamine(o-PDA) in a simulated wastewater. A rotor–stator reactor(RSR) was employed to create a high-gravity environment in order to enhance ozone-liquid mass transfer rate and possibly improve the degradation rate of o-PDA. The degradation efficiency of o-PDA(η) as well as the overall gas-phase volumetric mass transfer coefficient(KGa) were determined under different operating conditions of H_2O_2 concentration, initial o-PDA concentration, temperature of reaction, initial p H and rotation speed of RSR in attempt to establish the optimal conditions. Chemical oxygen demand reduction rate(rCOD) of wastewater treated at a particular set of conditions was also analyzed. Additionally, the intermediate products of degradation were identified using a gas chromatography-mass spectrometer(GC/MS) to further evaluate the extent of o-PDA degradation as well as establish its possible degradation pathway. Results were validated by comparison with those of sole use of ozone(O_3 process), and it was noted that η, KGa and rCODachieved by O_3/H_2O_2 process was 24.4%,31.6% and 25.2% respectively higher than those of O_3 process, indicating that H_2O_2 can greatly enhance ozonation of o-PDA. This work further demonstrates that an RSR can significantly intensify ozone-liquid mass transfer rate and thus provides a feasible intensification means for the ozonation of o-PDA as well as other recalcitrant organics.

Influence factors for the oxidation of pyrite by oxygen and birnessite in aqueous systems

The oxidation of exposed pyrite causes acid mine drainage, soil acidification, and the release of toxic metal ions. As the important abiotic oxidants in supergene environments,oxygen and manganese oxides participate in the oxidation of pyrite. In this work, the oxidation processes of natural pyrite by oxygen and birnessite were studied in simulated systems, and the influence of p H, Fe（II） and Cr（III） on the intermediates and redox rate was investigated. SO42-and elemental S were formed as the major and minor products,respectively, during the oxidation processes. Ferric（hydr） oxides including Fe（OH）3and goethite were formed with low degree of crystallinity. Low p H and long-term reaction facilitated the formation of goethite and ferric hydroxide, respectively. The rate of pyrite oxidation by birnessite was enhanced in the presence of air（oxygen）, and Fe（II） ions played a key role in the redox process. The addition of Fe（II） ions to the reaction system significantly enhanced the oxidation rate of pyrite; however, the presence of Cr（III） ions remarkably decreased the pyrite oxidation rate in aqueous systems. The introduction of Fe（II） ions to form a Fe（III）/Fe（II） redox couple facilitated the electron transfer and accelerated the oxidation rate of pyrite. The present work suggests that isolation from air and decreasing the concentration of Fe（II） ions in aqueous solutions might be effective strategies to reduce the oxidation rate of pyrite in mining soils.

Decoupled Ce-Nd Isotopic Systematics of the Neoproterozoic Huangling Intrusive Complex and Its Geological Significance, Eastern Three Gorges, South China

Cerium is one of multivalent rear earth elements, which can transfer from trivalence to tretavalence at oxidizing environment. This process may cause variable degrees of fractionation of Ce from other trivalent rear earth elements, and thus may provide specific insight into the geological processes associated with marked redoxomorphism. Multiple geochemical tracing of Sr-Nd-Ce isotopes are performed on the felsic and mafic intrusives of the Neoproterozoic（~800 Ma） Huangling complex located at the eastern Three Gorges, South China. The intrusive rocks exclusively show various extents of negative Ce anomalies. On the εCe-εNd plot, most samples from the mafic intrusions scatter within the second quadrant, whereas those from the felsic intrusions within the fourth Quadrant. Both of the two groups exhibit relatively large range of ？Ce（t） variation but limited ？Nd（t） range, which cause a deviation from the ＂crustal array＂ and reveal a decoupled Nd-Ce isotope correlation. The intermediate-felsic suite have varied Ce/Ce＊ ratios but broadly proximate εCe（t） values, indicating that their negative Ce anomalies were generated during the magmatism; on the contrary, a positive correlation between εCe（t） and Ce/Ce＊ is observed for the intermediate-mafic suite, an indication of an origin of post-magmatic alteration or metamorphism for their Ce anomalies. Calculation of model age, the occurrence age of negative Ce anomalies（TCe） for the intermediate-mafic samples infers that the alteration events took place 〉350 Ma. Data showed that negative Ce anomalies of the felsic intrusions may reflect an increase of oxygen fugacity during magma ascending, rather than an inheritance from their source rocks. This explanation implies that the Neoproterozoic magmatism occurred at the continental nucleus of the Yangtze block were developing at a geodynamic context of rapidly regional uplifting.