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《Chaos, solitons, and fractals》2007,31(4):1020-1023
Propagation of linear and nonlinear electron-acoustic waves (EAWs) in an unmagnetized collisionless plasma consisting of a cold electron fluid, non-thermal hot electrons and stationary ions are investigated. The standard normal-mode analysis is used to study the stability condition of linear (EAWs) waves. For nonlinear (EAWs) waves, a reductive perturbation method was employed to obtain a Korteweg–de Vries (KdV) equation for the first-order potential. The effects of a non-thermal distribution of hot electrons on the amplitude, width and energy of electrostatic solitary structures are also discussed. 相似文献
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Chaowei Yuan Wen Cui Yanjuan Sun Jiadong Wang Ruimin Chen Jin Zhang Yuxin Zhang Fan Dong 《中国化学快报》2020,31(3):751-754
It is of a great challenge to develop semiconductor photocatalysts with potential possibilities to simultaneously enhance photocatalytic efficiency and inhibit generation of toxic intermediates.In this study,we developed a facile method to induce the La doping and cationic vacancie(V(Zn))on ZnO for the highly efficient complete NO oxidation.The photocatalytic NO removal efficiency increases from 36.2%to 53,6%.Most importantly,a significant suppressed NO2 production also has been realized.According to the DFT calculations,ESR spectra and in situ FTIR spectra,the introduction of La^3+induce the redistribution of charge carriers in La-ZnO,which promote the production of·O2^- and lead to the formation of V(Zn)for the formation of·OH,contributing to the complete oxidation of NO to nitrate.Besides,the conversion pathway of photocatalytic NO oxidation has been elaborated,This work paves a new way to simultaneously realize the photocatalytic pollutants removal and the inhibition of toxic intermediates generation for efficient and safe air purification. 相似文献
4.
PageRank算法已经成为网络搜索引擎的核心技术。针对PageRank问题导出的线性方程组,首先将Krylov子空间方法中的重启GMRES(generalized minimal residual)方法与多分裂迭代(multi-splitting iteration,MSI)方法相结合,提出了一种重启GMRES修正的多分裂迭代法;然后,给出了该算法的详细计算流程和收敛性分析;最后,通过数值实验验证了该算法的有效性。 相似文献
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Xin-Rui Wang Hui-Min Cheng Xue-Wei Gao Wei Zhou Shu-Jing Li Xue-Li Cao Dongpeng Yan 《中国化学快报》2019,30(4):919-923
The inhibitor of melanin and the bacteriostatic agent kojic acid was inserted into Zn-Ti layered double hydroxide (LDH) by anion-exchange reaction. The structure, slow release, antibacterial and skin whitening activity were studied. 相似文献
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合成了一种新的钌(II)配合物[Ru(bpy)2(Hfip)](ClO4)2, 其中bpy代表2,2′-联吡啶, Hfip代表2-(9H-芴-2-基)-1H-咪唑-[4,5-f]-[1,10]-邻菲啰啉. 通过紫外可见光谱、荧光光谱、稳态荧光淬灭、与溴化乙锭的竞争实验、粘度测量和DNA热变性研究了该配合物与小牛胸腺DNA的键合性质. 结果表明, 该配合物能嵌入键合DNA, 键合常数Kb=8.6×105 L·mol-1 (50 mmol·L-1 NaCl). 相似文献
8.
《Spectrochimica Acta Part B: Atomic Spectroscopy》2005,60(5):699-703
The determination of chromium (VI) compounds in plants by electrothermal atomic absorption spectrometry (ET AAS) is proposed based on their leaching with 0.1 M Na2CO3. Due to the presence of relatively high amounts of Na2CO3 in the resulting samples, the temperature and time of pyrolysis and atomization stages must be optimized to minimize the influence of the matrix. A limit of detection (LOD) for determination of Cr(VI) in plants by ET AAS was found to be 0.024 μg g−1.The concentration of Cr(VI) and total chromium in plants collected in different geographical areas (South Africa and Russia), grown on soils high in chromium was determined. The concentration of Cr(VI) and total Cr in stems and leaves of plants was in the range of 0.04–0.7 μg g−1 and 0.5–10 μg g−1, respectively. The limited uptake of Cr(III) by plants, in comparison to its concentration in soil, can be explained by the very low solubility of natural Cr(III) compounds.Results for the determination of Cr(VI) were confirmed by the analysis of BCR CRM 545 (Cr(VI) in welding dust) with good agreement between certified (39.5 ± 1.3 μg mg−1) and found (38.8 ± 1.2 μg mg−1) values. The total concentration of Cr in plants has also been determined by ET AAS after dry ashing of samples at 650 °C. Results were confirmed by the analysis of BCR CRM 281 (Trace elements in Rye Grass) with good agreement between the found (2.12 ± 0.16 μg g−1) and certified value (2.14 ± 0.12 μg g−1). 相似文献
9.
A magnetic cotton/polyester fabric with photocatalytic, sonocatalytic, antibacterial and antifungal activities was successfully prepared through in-situ sonosynthesis method under ultrasound irradiation. The process involved the oxidation of Fe2+ to Fe3+ via hydroxyl radicals generated through bubbles collapse in ultrasonic bath. The treated samples were analyzed by X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy and vibrating sample magnetometry. Photocatalytic and sonocatalytic activities of magnetite treated fabrics were also evaluated toward Reactive Blue 2 decoloration under sunlight and ultrasound irradiation. Central composite design based on response surface methodology was applied to study the influence of iron precursor, pH and surfactant concentration to obtain appropriate amount for the best magnetism. Findings suggested the potential of one-pot sonochemical method to synthesize and fabricate Fe3O4 nanoparticles on cotton/polyester fabric possessing appropriate saturation magnetization, 95% antibacterial efficiency against Staphylococcus aureus and 99% antifungal effect against Candida albicans, 87% and 70% dye photocatalytic and sonocatalytic decoloration along with enhanced mechanical properties using only one iron rich precursor at low temperature. 相似文献
10.
环糊精包结作用下水溶液共聚合制备疏水改性阳离子聚丙烯酰胺及其絮凝效果研究 总被引:1,自引:0,他引:1
在水溶液中制备了甲基环糊精(Me-β-CD)/疏水单体2-苯氧乙基丙烯酸酯(POEA)的包结物(1a)。利用紫外-可见光谱及核磁共振波谱等检测手段研究了Me-β-CD与POEA的包合作用,并对包合物的结构、性能进行了表征和分析。同时在水溶液中引发丙烯酰胺(AM)、阳离子单体丙烯酰氧乙基三甲基氯化铵(DAC)以及1a的均相共聚合得到疏水修饰的阳离子聚丙烯酰胺P(AM-DAC-POEA),实现了用绿色方法合成高效高分子絮凝剂的目的,并对该高分子对高岭土模拟污水的絮凝效果进行了考察。 相似文献