This study focuses on the Danjiangkou reservoir, and investigates the release regulation of total nitrogen, nitrate, nitrite and ammonia from sediments as a function of temperature, perturbation and aeration conditions. Moreover, a simulation reactor was set up to explore the elimination of endogenous nitrogen pollution through high-efficient aerobic denitrification microorganism augmentation. Effects of high-efficient aerobic denitrification microorganisms on the microbial community structure in the sediments was also evaluated by means of high-throughput sequencing technology. The results indicated that increasing temperature could promote the release of nitrate and nitrite from sediments, while inhibiting the release of ammonium. Disturbances of water was beneficial to nitrogen release from sediments, and the nitrogen amount accumulated in the overlying water was proportional to the agitation speed. Concentrations of dissolved oxygen had great effects on the nitrogen release from sediments. It was found that the aeration treatment significantly reduced the release of total nitrogen and nitrite from sediments, and the subsequent accumulation in water. After addition of the a high-efficient aerobic denitrification bacteria Pseudomonas stutzeri (PCN-1) into the simulation reactor, concentrations of all the forms of nitrogen in the reactor increased at first and then decreased. On the 65th day of the experiment, removal rates of total nitrogen and nitrate released from sediments were as high as 75.87% and 79.96% respectively, suggesting effective control of the endogenous nitrogen. The relative abundance of Proteobacteria, Bacteroidetes and Spirochaetes in sediments was significantly increased after PCN-1 addition, so the microbial community structure in the sediments was changed by microbial augmentation treatment with PCN-1 as well.以丹江口水库为例,考察水库底泥在不同温度、扰动和曝气等条件下,总氮、硝氮、氨氮和亚硝氮的释放规律。设置模拟反应器,探究高效好氧脱氮微生物强化消除 水库底泥内源氮污染的效果,并运用高通量测序技术,分析高效好氧脱氮微生物对底泥微生物群落结构的影响。结果表明,温度升高会减少氨氮的释放,增加硝氮和 亚硝氮的积累;水体扰动会加速底泥中氮素释放,且上覆水中的氮素释放累积量与扰动速度成正比;溶解氧对底泥氮素释放有显著影响,曝气处理可以明显地降低底 泥中总氮和硝氮的释放及其在水体中的累积。在反应器中底泥-上覆水界面投加高效好氧脱氮微生物Pseudomonas stutzeri (PCN-1)后,反应器内各种形态的氮素都出现先上升、后下降的趋势;在反应器运行的第65天,底泥释放的总氮和硝氮的去除率分别高达75.87%和7 9.96%,底泥内源氮污染得到有效的控制。对比投加菌株前后的微生物群落结构,发现底泥中Proteobacteria, Bacteroidetes和Spirochaetes的相对丰度明显增加, PCN-1强化脱氮处理能够改变底泥的微生物群落结构。
We develop a non-perturbative approach for calculating the superconducting transition temperatures (\$T\_\c\\$) of liquids. The electron-electron scattering amplitude induced by electron-phonon coupling (EPC), from which the effective pairing interaction can be inferred, is related to the fluctuation of the \$T\$-matrix of electron scattering induced by ions. By applying the relation, EPC parameters can be extracted from a path-integral molecular dynamics simulation. For determining \$T\_\c\\$, the linearized Eliashberg equations are re-established in the non-perturbative context. We apply the approach to estimate \$T\_\c\\$ of metallic hydrogen liquids. It indicates that metallic hydrogen liquids in the pressure regime from \$0.5\$ to \$1.5$\backslash$mathrm\$\backslash$,TPa\\$ have \$T\_\c\\$ well above their melting temperatures, therefore are superconducting liquids.
Combined water pollution with the coexistence of heavy metals and organic contaminants is of great concern for practical wastewater treatment. In this study, a jaboticaba-like nanocomposite, titanate nanotubes supported TiO2 (TiO2/TiNTs), was synthesized by a two-step hydrothermal treatment. TiO2/TiNTs had large surface area, abundant of –ONa/H groups and fine crystal anatase phase, thus exhibited both good adsorptive performance for Cu(II) and high photocatalytic activity for phenanthrene degradation. The maximum Cu(II) adsorption capacity on TiO2/TiNTs was 115.0 mg/g at pH 5 according to Langmuir isotherm model, and >95% of phenanthrene was degraded within 4 h under UV light. TiO2/TiNTs showed about 10 times higher observed rate constant (kobs) for phenanthrene degradation compared to the unmodified TiNTs. More importantly, the coexistence of Cu(II) promoted photocatalytic degradation of phenanthrene, because the incorporated Cu(II) in the lattice of TiNTs could trap photo-excited electron and thus inhibited the electron-hole recombination. Density functional theory (DFT) calculation indicated that the sites of phenanthrene with high Fukui index (f0) preferred to be attacked by OH radicals. The quantitative structure–activity relationship (QSAR) analysis revealed that the degradation intermediates had lower acute toxicity and mutagenicity than phenanthrene. TiO2/TiNTs also owned high stability, as only slight loss of Cu(II) and phenanthrene removal efficiency was observed even after four reuse cycles. The developed material in this study is of great application potential for water or wastewater treatment with multi-contaminants, and this work can help us to better understand the mechanisms on reaction between Ti-based nanomaterials and different kinds of contaminants.
Conventional gyrotron backward-wave oscillators (gyro-BWOs) operate in a low-order mode, e.g., TE 0,1 mode. As the operating frequency extends to the terahertz (THz) band, the transverse size of low-order mode cavity shrinks, and the power capability is reduced, consequently. A solution to adopt an overmoded interaction cavity with a significantly enlarged index of the operating mode is valid on the condition that the challenging problem of mode competition can be controlled during the broadband frequency tuning. In this paper, a high-order whispering-gallery mode (WGM) THz gyro-BWO with a cathode-end output circuit is investigated. A segment-tapered circuit is applied to suppress the Q factors of competing modes and to obtain a the competition-free stable start-oscillation scenario. The theoretical result predicts that the effective frequency tuning range continuously covers between 252.3 and 260 GHz when the B-field is changed from 9.41 to 9.96 T. Our studies are beneficial to the development of high-performance sources for THz biomedical and material science applications.
Ternary solar cells have been proven to be an effective way to increase the power conversion efficiency (PCE) of organic solar cells (OSCs). Up to now, research effort has mostly focused on fullerene derivatives and acceptor–donor–acceptor (A–D–A) type non-fullerene acceptor-based ternary solar cells, while perylene diimide (PDI)-based ternary devices have been rarely studied. In this contribution, we introduced a new type of ternary solar cell based on a PDI-based small-molecule acceptor (PBI-Por) and a polymer donor (PTB7-Th) with a third PDI-based polymer acceptor (PDI-V). The introduction of PDI-V into the ternary blends not only broadens the absorption of blend films but also increases the electron mobilities. As a result, a high efficiency of 9.43% was obtained for the ternary OSC, which is 20% higher than that of the binary OSC. Detailed studies indicate that PDI-V showed good compatibility with PBI-Por in the blend films, which demonstrates a promising way to fabricate high-performance PDI-based OSCs.
