Nanocomposite conductive fiber has been newly developed as a lightweight material with high flexibility and strong weavability, which can meet the requirements of flexible wearable devices. Herein, lightweight porous aramid nanofibers (ANF) and carbon nanotube (CNT) aerogel fibers coated with polypyrrole (PPy) layers are prepared by a wet spinning method for motion detection and information transmission. The ANF/CNT/PPy aerogel fiber with low density (56.3 mg/cm3), conductivity (6.43 S/m), and tensile strength (2.88 MPa) were used as motion sensors with high sensitivity (0.12) and long life (1000 cycles). At the same time, the differential conductivity of aerogel fibers is utilized to reduce the information transmission time (up to 46%). High- and low-temperature-resistant (−196 to 100 °C) aerogel fibers are also available as a quick heater and ionic solution detector. In summary, the prepared ANF/CNT/PPy aerogel fiber can be used as a multifunctional sensor for human-health detection and motion monitoring.

This paper is concerned with uniqueness in inverse electromagnetic scattering with phaseless farfield pattern at a fixed frequency. In our previous work [SIAM J. Appl. Math. 78 (2018), [3024][3025][3026][3027][3028][3029][3030][3031][3032][3033][3034][3035][3036][3037][3038][3039], by adding a known reference ball into the acoustic scattering system, it was proved that the impenetrable obstacle and the index of refraction of an inhomogeneous medium can be uniquely determined by the acoustic phaseless far-field patterns generated by infinitely many sets of superpositions of two plane waves with different directions at a fixed frequency. In this paper, we extend these uniqueness results to the inverse electromagnetic scattering case. The phaseless far-field data are the modulus of the tangential component in the orientations e φ and e θ , respectively, of the electric far-field pattern measured on the unit sphere and generated by infinitely many sets of superpositions of two electromagnetic plane waves with different directions and polarizations. Our proof is mainly based on Rellich's lemma and the Stratton-Chu formula for radiating solutions to the Maxwell equations. 1 generated by one plane wave is invariant under the translation of the scatterers. This implies that it is impossible to recover the location of the scatterer from the phaseless far-field data with one plane wave as the incident field. Several iterative methods have been proposed in [12,13,14,21] to reconstruct the shape of the scatterer. Under a priori condition that the sound-soft scatterer is a ball or disk, it was proved in [22] that the radius of the scatterer can be uniquely determined by a single phaseless far-field datum. It was proved in [23] that the shape of a general, sound-soft, strictly convex obstacle can be uniquely determined by the phaseless far-field data generated by one plane wave at a high frequency. However, there is no translation invariance property for phaseless near-field data. Therefore, many numerical algorithms for inverse scattering problems with phaseless near-field data have been developed (see, e.g., [3,4,6,18,32,36] for the acoustic case and [5] for the electromagnetic case). Uniqueness results and stability have also been established for inverse scattering problems with phaseless near-field data (see [16,17,19,24,26,27,30,37,42,43] for the acoustic and potential scattering case and [29,37] for the electromagnetic scattering case).Recently in [38], it was proved that the translation invariance property of the phaseless far-field pattern can be broken by using superpositions of two plane waves as the incident fields with an interval of frequencies. Following this idea, several algorithms have been developed for inverse acoustic scattering problems with phaseless far-field data, based on using the superposition of two plane waves as the incident field (see [38,39,40]). Further, by using the spectral properties of the far-field operator, rigorous uniqueness results have also been established in [34] for inverse acousti...

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This paper is concerned with uniqueness in inverse acoustic scattering with phaseless far-field data at a fixed frequency. In our previous work (SIAM J. Appl. Math. 78 (2018), 1737-1753, by utilizing spectral properties of the far-field operator we proved for the first time that the obstacle and the index of refraction of an inhomogeneous medium can be uniquely determined by the phaseless far-field patterns generated by infinitely many sets of superpositions of two plane waves with different directions at a fixed frequency under the a priori assumption that the obstacle is known to be a sound-soft or non-absorbing impedance obstacle and the index of refraction n of the inhomogeneous medium is real-valued and satisfies that either n − 1 ≥ c 1 or n − 1 ≤ −c 1 in the support of n − 1 for some positive constant c 1 . In this paper, we remove the a priori assumption on the obstacle and the index of refraction of the inhomogeneous medium by adding a reference ball to the scattering system together with a simpler method of using Rellich's lemma and Green's representation formula for the scattering solutions. Further, our new method is also used to prove uniqueness in determining a locally rough surface from the phaseless far-field patterns corresponding to infinitely many sets of superpositions of two plane waves with different directions as the incident fields at a fixed frequency.

A new composite absorbent with multifunctional and environmental-friendly structures was prepared using chitosan, diatomite and polyvinyl alcohol as the raw materials, and glutaraldehyde as a cross-linking agent. The structure and morphology of the composite absorbent, and its adsorption properties of Hg(II) in water were characterized with Fourier transform infrared (FT-IR) spectra, scanning electron microscope (SEM), X-ray diffraction (XRD), Brunauer Emmett Teller (BET) measurements and ultraviolet–visible (UV–Vis) spectra. The effect of the pH value and contact time on the removal rate and absorbance of Hg(II) was discussed. The adsorption kinetic model and static adsorption isotherm and regeneration of the obtained composite absorbent were investigated. The results indicated that the removal of Hg(II) on the composite absorbent followed a rapid adsorption for 50 min, and was close to the adsorption saturation after 1 h, which is in accord with the Langmuir adsorption isotherm model and the pseudo-second-order kinetic model. When the pH value, contact time and the mass of the composite absorbent was 3, 1 h and 100 mg, respectively, the removal rate of Hg(II) on the composite absorbent reached 77%, and the maximum adsorption capacity of Hg(II) reached 195.7 mg g−1.