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61.
62.
Harlan W. Stockman 《Soil & Sediment Contamination》1998,7(5):615-647
The solubility of plutonium was estimated for waste buried at the Greater Confinement Disposal site in Nevada. The EQ3/6 thermochemical database was modified to include recent data on Pu complex formation, and the solubilities of two critical phases (probertite (CaNaB5O9·5H2O), added as a backfill material; and Ca sac-charate) were determined by experiment. Reaction path runs were used to model effects of cellulose degradation, including complexation of actinides by organic acids and carbonate, decay of the complexing agents, and the buildup and diffusive loss of CO2 through the permeable alluvium. For most waste interaction scenarios, long-term (≈103 years) concentrations of Pu in pore waters are ≤10?7 molal and are dominated by carbonate complexes, although organic complexes could dominate in the first ≈103 years. In unusual circumstances, carbonation of buried lithium could produce very high Pu solubilities; however, even in such a system, a slight lowering of the effective redox potential dramatically lowers Pu solubility. A sensitivity analysis suggests that the “base case” calculations are conservative, tending to overestimate long-term solubility, with the system redox and the identity of the organic acids the major sources of uncertainty. 相似文献
63.
Qayyum Husain 《Critical reviews in biotechnology》2013,33(4):201-221
ABSTRACTRecently, the enzymatic approach has attracted much interest in the decolorization/degradation of textile and other industrially important dyes from wastewater as an alternative strategy to conventional chemical, physical and biological treatments, which pose serious limitations. Enzymatic treatment is very useful due to the action of enzymes on pollutants even when they are present in very dilute solutions and recalcitrant to the action of various microbes participating in the degradation of dyes. The potential of the enzymes (peroxidases, manganese peroxidases, lignin peroxidases, laccases, microperoxidase-11, polyphenol oxidases, and azoreductases) has been exploited in the decolorization and degradation of dyes. Some of the recalcitrant dyes were not degraded/decolorized in the presence of such enzymes. The addition of certain redox mediators enhanced the range of substrates and efficiency of degradation of the recalcitrant compounds. Several redox mediators have been reported in the literature, but very few of them are frequently used (e.g., 1-hydroxybenzotriazole, veratryl alcohol, violuric acid, 2-methoxy-phenothiazone). Soluble enzymes cannot be exploited at the large scale due to limitations such as stability and reusability. Therefore, the use of immobilized enzymes has significant advantages over soluble enzymes. In the near future, technology based on the enzymatic treatment of dyes present in the industrial effluents/wastewater will play a vital role. Treatment of wastewater on a large scale will also be possible by using reactors containing immobilized enzymes. 相似文献
64.
Jia Liang Zonghao Liu Longbin Qiu Zafer Hawash Lingqiang Meng Zhifang Wu Yan Jiang Luis K. Ono Yabing Qi 《Liver Transplantation》2018,8(20)
In this work all‐inorganic perovskite CsPbIBr2 are doped with Mn to compensate their shortcomings in band structure for the application of perovskite solar cells (PSCs). The novel Mn‐doped all‐inorganic perovskites, CsPb1?xMnxI1+2xBr2?2x, are prepared in ambient atmosphere. As the concentration of Mn2+ ions increases, the bandgaps of CsPb1?xMnxI1+2xBr2?2x decrease from 1.89 to 1.75 eV. Additionally, when the concentration of Mn dopants is appropriate, this novel Mn‐doped all‐inorganic perovskite film shows better crystallinity and morphology than its undoped counterpart. These advantages alleviate the energy loss in hole transfer and facilitate the charge‐transfer in perovskites, therefore, PSCs based on these novel CsPb1?xMnxI1+2xBr2?2x perovskite films display better photovoltaic performance than the undoped CsPbIBr2 perovskite films. The reference CsPbIBr2 cell reaches a power conversion efficiency (PCE) of 6.14%, comparable with the previous reports. The CsPb1?xMnxI1+2xBr2?2x cells reach the highest PCE of 7.36% (when x = 0.005), an increase of 19.9% in PCE. Furthermore, the encapsulated CsPb0.995Mn0.005I1.01Br1.99 cells exhibit good stability in ambient atmosphere. The storage stability measurements on the encapsulated PSCs reveal that PCE is dropped by only 8% of the initial value after >300 h in ambient. Such improved efficiency and stability are achieved using low‐cost carbon electrodes (without expensive hole transport materials and Au electrodes). 相似文献
65.
Electronic and Defective Engineering of Electrospun CaMnO3 Nanotubes for Enhanced Oxygen Electrocatalysis in Rechargeable Zinc–Air Batteries
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Shengjie Peng Xiaopeng Han Linlin Li Shulei Chou Dongxiao Ji Huangjiao Huang Yonghua Du Jian Liu Seeram Ramakrishna 《Liver Transplantation》2018,8(22)
Rational design and massive production of bifunctional catalysts with superior oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activities are essential for developing metal–air batteries and fuel cells. Herein, controllable large‐scale synthesis of sulfur‐doped CaMnO3 nanotubes is demonstrated via an electrospinning technique followed by calcination and sulfurization treatment. The sulfur doping can not only replace oxygen atoms to increase intrinsic electrical conductivity but also introduce abundant oxygen vacancies to provide enough catalytically active sites, which is further demonstrated by density functional theory calculation. The resulting sulfur‐modified CaMnO3 (CMO/S) exhibits better electrocatalytic activity for ORR and OER in alkaline solution with higher stability performance than the pristine CMO. These results highlight the importance of sulfur treatment as a facile yet effective strategy to improve the ORR and OER catalytic activity of the pristine CaMnO3. As a proof‐of‐concept, a rechargeable Zn–air battery using the bifunctional catalyst exhibits a small charge–discharge voltage polarization, and long cycling life. Furthermore, a solid‐state flexible and rechargeable Zn–air battery gives superior discharge–charge performance and remarkable stability. Therefore, the CMO/S nanotubes might be a promising replacement to the Pt‐based electrocatalysts for metal–air batteries and fuel cells. 相似文献
66.
Designing Redox‐Stable Cobalt–Polypyridyl Complexes for Redox Flow Batteries: Spin‐Crossover Delocalizes Excess Charge
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Chunzhen Yang Georgios Nikiforidis Ji Young Park Jonghoon Choi Yong Luo Liang Zhang Shi‐Cheng Wang Yi‐Tsu Chan Jihun Lim Zhaomin Hou Mu‐Hyun Baik Yunho Lee Hye Ryung Byon 《Liver Transplantation》2018,8(14)
Redox‐active organometallic molecules offer a promising avenue for increasing the energy density and cycling stability of redox flow batteries. The molecular properties change dramatically as the ligands are functionalized and these variations allow for improving the solubility and controlling the redox potentials to optimize their performance when used as electrolytes. Unfortunately, it has been difficult to predict and design the stability of redox‐active molecules to enhance cyclability in a rational manner, in part because the relationship between electronic structure and redox behavior has been neither fully understood nor systematically explored. In this work, rational strategies for exploiting two common principles in organometallic chemistry for enhancing the robustness of pseudo‐octahedral cobalt–polypyridyl complexes are developed. Namely, the spin‐crossover between low and high‐spin states and the chelation effect emerging from replacing three bidentate ligands with two tridentate analogues. Quantum chemical models are used to conceptualize the approach and make predictions that are tested against experiments by preparing prototype Co‐complexes and profiling them as catholytes and anolytes. In good agreement with the conceptual predictions, very stable cycling performance over 600 cycles is found. 相似文献
67.
Review on Challenges and Recent Advances in the Electrochemical Performance of High Capacity Li‐ and Mn‐Rich Cathode Materials for Li‐Ion Batteries
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Prasant Kumar Nayak Evan M. Erickson Florian Schipper Tirupathi Rao Penki Nookala Munichandraiah Philipp Adelhelm Hadar Sclar Francis Amalraj Boris Markovsky Doron Aurbach 《Liver Transplantation》2018,8(8)
Li and Mn‐rich layered oxides, xLi2MnO3·(1–x)LiMO2 (M=Ni, Mn, Co), are promising cathode materials for Li‐ion batteries because of their high specific capacity that can exceed 250 mA h g?1. However, these materials suffer from high 1st cycle irreversible capacity, gradual capacity fading, low rate capability, a substantial charge‐discharge voltage hysteresis, and a large average discharge voltage decay during cycling. The latter detrimental phenomenon is ascribed to irreversible structural transformations upon cycling of these cathodes related to potentials ≥4.5 V required for their charging. Transition metal inactivation along with impedance increase and partial layered‐to‐spinel transformation during cycling are possible reasons for the detrimental voltage fade. Doping of Li, Mn‐rich materials by Na, Mg, Al, Fe, Co, Ru, etc. is useful for stabilizing capacity and mitigating the discharge‐voltage decay of xLi2MnO3·(1–x)LiMO2 electrodes. Surface modifications by thin coatings of Al2O3, V2O5, AlF3, AlPO4, etc. or by gas treatment (for instance, by NH3) can also enhance voltage and capacity stability during cycling. This paper describes the recent literature results and ongoing efforts from our groups to improve the performance of Li, Mn‐rich materials. Focus is also on preparation of cobalt‐free cathodes, which are integrated layered‐spinel materials with high reversible capacity and stable performance. 相似文献
68.
69.
Effects of manganese toxicity on photosynthesis of white birch (Betula platyphylla var. japonica) seedlings 总被引:5,自引:0,他引:5
The effects of manganese (Mn) toxicity on photosynthesis in white birch ( Betula platyphylla var. japonica ) leaves were examined by the measurement of gas exchange and chlorophyll fluorescence in hydroponically cultured plants. The net photosynthetic rate at saturating light and ambient CO2 (Ca ) of 35 Pa decreased with increasing leaf Mn concentrations. The carboxylation efficiency, derived from the difference in CO2 assimilation rate at intercellular CO2 pressures attained at Ca of 13 Pa and O Pa, decreased with greater leaf Mn accumulation. Net photosynthetic rate at saturating light and saturating CO2 (5%) also declined with leaf Mn accumulation while the maximum quantum yield of O2 evolution at saturating CO2 was not affected. The maximum efficiency of PSII photochemistry (Fv /Fm ) was little affected by Mn accumulation in white birch leaves over a wide range of leaf Mn concentrations (2–17 mg g−1 dry weight). When measured in the steady state of photosynthesis under ambient air at 430 μmol quanta m−2 s−1 , the levels of photochemical quenching (qP) and the excitation capture efficiency of open PSII (F'v /F'm ) declined with Mn accumulation in leaves. The present results suggest that excess Mn in leaves affects the activities of the CO2 reduction cycle rather than the potential efficiency of photochemistry, leading to increases in QA reduction state and thermal energy dissipation, and a decrease in quantum yield of PSII in the steady state. 相似文献
70.
Maureen D. Keller Rhonda C. Selvin Wolfgang Claus Robert R. L. Guillard 《Journal of phycology》1987,23(4):633-638
A medium (K) developed for culturing fastidious oceanic phytoplankton has been tested using recently isolated ultraphytoplankton clones representing at least seven different algal classes. The medium was designed to satisfy as completely as possible the nutritional requirements of this diverse group of phytoplankters. Important aspects are the addition of selenium, the inclusion of both nitrate and ammonium, an increased level of chelation and a moderate level of pH buffering. The seawater-based version of this medium has been tested on 200 clones of which 186 grew reliably. A synthetic counterpart (AK) was tested on 40 of the more difficult clones and 27 grew well; 13 grew not all. While neither medium meets the exacting nutritional needs of all the ultraphytoplankton forms tested, they are excellent for most oceanic clones and are very successful for the isolation and establishment in culture of new oceanic phytoplankton clones. 相似文献