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Scheme depicting the ion-imprinting process on GO surface by RAFT polymerization.

In the present study, a Cr(III)-imprinted polymer (Cr(III)-IIP) was prepared by an easy one-step sol-gel reaction with a surface imprinting technique on the support of silica mesoporous material. A new SPE method for the speciation, separation, preconcentration, and determination of Cr(III) and Cr(VI) by inductively coupled plasma atomic emission spectrometry and UV on the mesoporous-imprinted polymer adsorbent was developed. The structure of the imprinted polymer was characterized by Fourier transform infrared spectroscopy, X-ray powder diffraction, transmission electron microscopy, and nitrogen adsorption-desorption isotherms. The adsorption kinetics, thermodynamics behavior, and recognition ability toward Cr(III) on Cr(III)-IIP and nonimprinted polymer were compared. The results showed that Cr(III)-IIP had higher selectivity and nearly a two times larger Langmuir adsorption capacity (38.50 mg/g) than that of NIP. The proposed method has been successfully applied in the determination and speciation of chromium in natural water samples with satisfactory results.

In the present work, a novel two-dimensional (2D) nickel ion-imprinted polymer (RAFT-IIP) has been successfully synthesized based on the graphene oxide/SiO2 composite by reversible addition-fragmentation chain-transfer (RAFT) polymerization. The imprinted materials obtained are characterized by Fourier transmission infrared spectrometry (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The results show that the thermal stability of the graphene oxide/SiO2 composite is obviously higher than that of graphene oxide. RAFT-IIP possesses an excellent 2D homogeneous imprinted polymer layer, which is a well-preserved unique structure of graphene oxide/SiO2. Owing to the intrinsic advantages of RAFT polymerization and 2D imprinted material, RAFT-IIP demonstrate a superior specific adsorption capacity (81.73 mg/g) and faster adsorption kinetics (30 min) for Ni(II) in comparison to the ion-imprinted polymer prepared by traditional radical polymerization and based on the common carbon material. Furthermore, the adsorption isotherm and selectivity toward Ni(II) onto RAFT-IIP and nonimprinted polymer (NIP) are investigated, indicating that RAFT-IIP has splendid recognizing ability and a nearly 3 times larger adsorption capacity than that of NIP (30.94 mg/g). Moreover, a three-level Box-Behnken experimental design with three factors combining the response surface method is utilized to optimize the desorption process. The optimal conditions for the desorption of Ni(II) from RAFT-IIP are as follows: an HCl-type eluent, an eluent concentration of 2.0 mol/L, and an eluent volume of 10 mL.

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A Position and Orientation System (POS) integrating an Inertial Navigation Systems (INS) and the Global Positioning System (GPS) is a key component of remote sensing motion compensation. It can provide reliable and high-frequency high-precision motion information using a Kalman Filter (KF) during GPS availability. However, the performance of a POS significantly degrades during GPS outages. To maintain reliable POS outputs, this paper proposes a new hybrid predictor based on modelling the nonlinear time-series data-driven INS-errors using Noisy Input Gaussian Process Regression (NIGPR), which takes the input noise into account. The proposed approach is used to learn the nonlinear INS-errors model when GPS signals are available. When GPS outages occur, it starts to predict the observation measurement, and then feeds it to a KF as a virtual update to estimate all the INS errors. The proposed approach is verified in a real airplane, which combines a POS and Synthetic Aperture Radar (SAR). Experimental results show that the proposed approach significantly improves the performance of the POS, with improvements more than 90% better than a KF and 10% better than a Gaussian Process Regression (GPR/KF) combination during various GPS outages.

In this work, 3D CdIn2S4 nano-octahedron/2D ZnO nanosheet heterojunctions (CIS/ZO-x) were fabricated for the first time via a facile and green impregnation-hydrothermal method, where three-dimensional (3D) CdIn2S4 nano-octahedra densely anchor onto both sides of 2D ZnO nanosheets to form an embedded nanostructure with intimate interfacial contacts. Various characterization techniques were adopted to measure the morphologies, structures and optical properties of the as-prepared CIS/ZO-x heterojunctions in detail. The photocatalytic performance of the as-prepared CIS/ZO-x was evaluated via the photodegradation of tetracycline hydrochloride (TCH) under visible light irradiation, and the result shows that the hybridization of ZnO nanosheets with CdIn2S4 nano-octahedra significantly enhances the photocatalytic activity of heterojunctions. The highly stable and reusable sample CIS/ZO-2 possesses the highest photocatalytic activity (94.04%), and its rate constant (k = 0.06357 min-1) is about 4.96 and 22.31 times as high as those of pure CdIn2S4 and ZnO. Interestingly, the removal efficiency of TCH and the rate constant are also much higher than those of numerous previously reported composite photocatalysts. The synergistic effect and the unique 3D/2D hybrid structure with intimate interfacial contacts are primarily responsible for the enhanced photocatalytic activity. A possible photocatalytic mechanism for the TCH photodegradation over the CIS/ZO sample is also proposed. This work provides a novel 3D/2D composite photocatalyst for the efficient removal of antibiotic pollutants and will be helpful for designing other 3D/2D heterojunctions.

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