This paper reviews current remediation technologies that use chelating agents for the 16 mobilization and removal of potentially toxic metals from contaminated soils. These 17 processes can be done in situ as enhanced phytoextraction, chelant enhanced electrokinetic 18 extraction and soil flushing, or ex situ as the extraction of soil slurry and soil heap/column 19 leaching. Current proposals on how to treat and recycle waste washing solutions after soil is 20 washed are discussed. The major controlling factors in phytoextraction and possible strategies 21 for reducing the leaching of metals associated with the application of chelants are also 22 reviewed. Finally, the possible impact of abiotic and biotic soil factors on the toxicity of 23 metals left after the washing of soil and enhanced phytoextraction are briefly addressed. 24 25
An ultrathin and broadband absorber is investigated in this paper. The metamaterial absorber is composed of a periodic array of loop-dielectric multilayered structure. By tuning the scale factor of the loop and the height of every layer, a desirable refractive index dispersion spectrum is realized, which is the reason to realize a successive anti-reflection in a wide frequency range. The interference mechanism and resonance absorption are identified through analytical derivation and numerical simulations. Numerical results show that the absorption at normal incidence is above 90% in the frequency range of 8.37–21 GHz. Moreover, the structure has a thickness of 3.65 mm (only 0.10λ to 0.26λ at the lowest and highest frequencies, respectively). The explanation to the physical mechanism of the metamaterial absorber is presented and verified.
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