3 research outputs found
Reconstruction of noisy images via stochastic resonance in nematic liquid crystals
Abstract We employ nematic liquid crystals as the nonlinear medium to recover noisy images via stochastic resonance, in which nonlinear coupling allows signals to grow at the expense of noise. The process is theoretically analyzed and the cross-correlation is numerically calculated. It is found that the quality of output images is affected by the input noise intensity, the applied voltage and the correlation length of noise light. Noise-hidden images can be effectively recovered by optimizing these parameters. The results suggest that nematic liquid crystals can be used for reconstruction of noisy images via stochastic resonance based on modulation instability with molecule reorientation nonlinearity
Pulse signal restoration via stochastic resonance in a Fabry–Perot cavity with an intracavity nematic liquid crystal film
Environmental Risk Implications of Metals in Sludges from Waste Water Treatment Plants: The Discovery of Vast Stores of Metal-Containing Nanoparticles
Nanoparticle
(NP) assessment in sludge materials, although of growing
importance in eco- and biotoxicity studies, is commonly overlooked
and, at best, understudied. In the present study, sewage sludge samples
from across the mega-city of Shanghai, China were investigated for
the first time using a sequential extraction method coupled with single
particle inductively coupled plasma mass spectrometry (SP-ICP-MS)
to quantify the abundance of metal-containing NPs in the extraction
fractions and transmission electron microscopy to specifically identify
the nanophases present. In general, most sludges observed showed high
concentrations of Cr, Cu, Cd, Ni, Zn, and Pb, exceeding the maximum
permitted values in the national application standard of acid soil
in China. NPs in these sludges contribute little to the volume and
mass but account for about half of the total particle number. Based
on electron microscopy techniques, various NPs were further identified,
including Ti-, Fe-, Zn-, Sn-, and Pb-containing NPs. All NPs, ignored
by traditional metal risk evaluation methods, were observed at a concentration
of 10<sup>7</sup> −10<sup>11</sup> particles/g within the bioavailable
fraction of metals. These results indicate the underestimate or misestimation
in evaluating the environmental risks of metals based on traditional
sequential extraction methods. A new approach for the environmental
risk assessment of metals, including NPs, is urgently needed