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A highly selective and sensitive optical sensor was developed to colorimetric detect trace Fe3+ ions in aqueous solution. The sensor was the sulfasalazine (SSZ) functionalized microgels (SSZ-MGs), which were fabricated via in-situ quaternization reaction. The obtained SSZ-MGs had hydrodynamic radius of about 259 ± 24 nm with uniform size distribution at 25 °C. The SSZ-MG aqueous suspensions can selectively and sensitively response to Fe3+ ions in aqueous solution at 25 °C and pH of 5.6, which can be quantified by UV-visible spectroscopy and also easily distinguished by the naked eye. Job’s plot indicated that the molar binding ratio of SSZ moiety in SSZ-MGs to Fe3+ was close to 1:1 with an apparent association constant of 1.72 × 104 M−1. A linear range of 0–12 μM with the detection limit of 0.110 μM (0.006 mg/L) was found. The obtained detection limit was much lower than the maximum allowance level of Fe3+ ions in drinking water (0.3 mg/L) regulated by the Environmental Protection Agency (EPA) of the United States. The existence of 19 other species of metal ions, namely, Ag+, Li+, Na+, K+, Ca2+, Ba2+, Cu2+, Ni2+, Mn2+, Pb2+, Zn2+, Cd2+, Co2+, Cr3+, Yb3+, La3+, Gd3+, Ce3+, and Bi3+, did not interfere with the detection of Fe3+ ions.

This paper focuses on the design and modeling of a hydraulic soft actuator which can perform space motion with multiple degrees of freedom (DOF). The cylinder soft actuator made of elastomer has three fiber-reinforced hydraulic chambers distributed symmetrically. By controlling the pressure vector in the chambers, the motion of the soft actuator can be expressed by three independent variables including axial elongation, bending angle, and azimuth angle. This paper firstly presents the actuation principle, structural design, and fabrication method of the soft actuator. Secondly, the relationship between the input pressure and the axial length of the chamber is derived by taking the nonlinear deformation behavior of the elastomer into account, which is seldom considered in the state of the art. Thirdly, the kinematics of the soft actuator is modeled to predict the coordinates of its tip position with the piecewise constant-curvature (PCC) assumption. Finally, an experimental platform is set up and a series of experiments are implemented to identify some parameters which are difficult to be quantified analytically as well as to validate the developed model. The results show that the measured data are in good accordance with the predicted data. In addition, a model-based open-loop control experiment is carried out to realize the path following.

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Thermosensitive fluorescent microgels (HMQC-MGs) were developed as selective and sensitive sensing systems for the detection of trace Fe3+ and Mn2+ ions in aqueous solutions. HMQC-MGs, which were synthesized via in situ quaternization reaction and surfactant free emulsion copolymerization (SFEP) of N-isopropylacrylamide (NIPAm) and 1-vinylimidazole (VIM) in the presence of 1,6-dibromhexane and 3-hydroxy-2-methyl-4-quinolinecarboxylicacid (HMQC), were fluorescent and thermosensitive with a hydrodynamic radius of 153 ± 2 nm at 25 °C in aqueous solutions. Interestingly, HMQC-MGs exhibited different affinities and distinct fluorescent patterns toward various metal ions in aqueous solutions with different pH values (2, 7, and 12). Selective and fast fluorescent quenching of HMQC-MGs was observed in the presence of Fe3+ and Mn2+ ions at pH 2 and pH 12, respectively. The detection limits (D Ls) of Fe3+ and Mn2+ ions were determined to be about 60 and 247 nM, respectively, which are far lower than the safety limits in drinking water regulated by the U.S. Environmental Protection Agency (EPA). The mechanisms of fluorescence quenching after the addition of Fe3+ and Mn2+ ions were attributed to the combined dynamic/static quenching and inner filter effect, respectively. HMQC-MG fluorescent microgels could be potentially applied as sensing systems for the detection of trace Fe3+ and Mn2+ ions in real water samples.

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Herein, a straightforward and efficient route for the construction of dual α,β-C(sp3)–H functionalized cyclic N-aryl amines using a combination of electrocatalysis and iron catalysis is disclosed. This approach is achieved...