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Three novel metal–organic assemblies (MOAs), namely, [Ag(2,4′-Hpdc)(4,4′-bpy)]n (1), [Ag(2,2′-Hpdc)(4,4′-bpy)0.5]n (2), and [Cu(2,2′-Hpdc)2(1,4-bib)]n (3) [2,4′-H2pdc = 2,4′-biphenyldicarboxylic acid; 2,2′-H2pdc = 2,2′-biphenyldicarboxylic acid; 4,4′-bpy = 4,4′-bipyridine; 1,4-bib = 1,4-bis(1-imidazolyl)benzene] have been hydrothermally synthesized by using mixed ligands and characterized by single crystal X-ray diffraction, infrared (IR), elemental analysis and thermogravimetric analysis (TGA). The crystal structures of the three compounds indicate that the hydrogen bonding (C–H…O and C–H…π) and π…π stacking interactions play critical roles in the formation of an extended supramolecular array. The combination of C–H…π and π…π stacking interactions endow 1 with a 3D network. 2 displays a rare 3D structure with a unique 1D structure based on an eight-membered {Ag2C2O4} ring and compound 3 shows a 1D chain structure, which is propagated to form an extended 3D structure only by C–H…π hydrogen bonding. The two Ag(i)-compounds display blue emissions in the solid state at 298 K and 77 K. More significantly, compound 1 shows excellent selectivity, fast detection time (＜5 min), and high sensitivity (detection limit, 9.63 nM) for Hg2+ ions in aqueous solution due to a great enhancement of 1-luminescence, which can be attributed to Hg2+ cation binding by a non-coordinated carboxyl group efficiently. This is a rare example of Hg2+ detection in aqueous solution based on luminescent silver MOAs. In addition, adsorption spectra reveal the semiconductive nature (2.76 eV for 2, but not detected for 1), thus the role of the Ag…Ag interaction in controlling the performance of the semiconductor properties is highlighted. [ABSTRACT FROM AUTHOR]

Background: Although Pneumatic Artificial Muscle (PAM) has a promising future in rehabilitation robots, it's difficult to realize accurate position control due to its highly nonlinear properties.Objective: This paper deals with position control of PAM.Methods: To describe the hysteresis inside PAM, a polynomial based phenomenological function is developed. Based on the phenomenological model for PAM and analysis of pressure dynamics within PAM, an adaptive cascade controller is proposed. Both outer loop and inner loop employ BP Neural Network tuned PID algorithm. The outer loop is to handle high nonlinearities and unmodeled dynamics of PAM, while the inner loop is responsible for nonlinearities caused by pressure dynamics.Results: Experimental results show high tracking accuracy as compared with a convention PID controller.Conclusion: The proposed controller is effective in improving performance of PAM and will be implemented in a rehabilitation robot. [ABSTRACT FROM AUTHOR]

Background: When using upper limb exoskeletons that assist the movement of physically weak people, safety should be the most important index.Objective: In this paper, a passively safe, cable-driven upper limb exoskeleton with parallel actuated joints, which perfectly mimics human motions, is proposed.Methods: Compared with the existing upper limb exoskeletons which are mostly designed only considering the realization of functional properties, and having poor wearabity, a passively safe prototype for motion assistance based on human anatomy structure has been developed in our design. This design is based on the prior exoskeleton structure with the adoption of a gravity balanced device.Results and Conclusion: The gravity balanced mechanism was confirmed in theory and simulation, showing it has a positive effect on balance. [ABSTRACT FROM AUTHOR]

Polymer‐based radiation shielding materials are receiving more and more interests due to their desirable advantages in lightweight and maneuverability. Herein, we employ polypropylene (PP) as the matrix to construct γ‐ray shielding composites through the embedment of PbO particles with a wet reaction melt blending method. From the changes in dynamic rheological behaviors and fracture surface of PP/PbO composite, it can be found that the gradient addition of PbO particles facilitates the formation of heterogeneous network structure with, and high PbO content may make the composites undergo a “liquid–solid” transition. Rheological temperature and time scanning show that both PbO content and heterogeneous network structure greatly contribute to the storage modulus (G') and thermal stability. The γ‐ray (137Cs) shielding tests manifest that BPP/PbO‐4 has the best shielding performance, whose thicknesses of half value layer (HVL) and tenth value layer (TVL) are 0.32 and 1.05 cm, respectively, obviously smaller than those shielding materials ever reported. The analyses on effective atomic number (Zeff) and effective electron density (NE) reveal that the good shielding performance of BPP/PbO‐4 benefits from its proper content and dispersion of PbO particles. [ABSTRACT FROM AUTHOR]

Due to the high carcinogenicity and bioaccumulation effects of dichromate ions in the human body, sensitive and rapid detection of Cr 2 O 7 2- ions is necessary. Herein, two lanthanide coordination polymers based on a linear dicarboxylic acid ligand, named {Ln(cpon)(Hcpon)(H 2 O) 3 } n [Ln = Tb, Tbcpon ; Eu, Eucpon ; H 2 cpon = 5-(4-carboxy-phenoxy)-nicotinic acid], have been successfully synthesized. These two isostructural compounds contain one-dimensional zigzag chains that consist of uncoordinated carboxyl groups and pyridine groups in the framework, and the one-dimensional chains can further form a three-dimensional supramolecular stacking structure by intermolecular interaction. Both Tbcpon and Eucpon show good luminescence performance and high stability. Tbcpon exhibits a good ability to sense Cr 2 O 7 2- ions in aqueous solution. Moreover, the composite film material composed of Tbcpon and poly(methyl methacrylate) (PMMA) exhibits superior luminescence properties compared to those of pure Tbcpon . The Tbcpon-PMMA film exhibits an excellent ability to recognize Cr 2 O 7 2- ions with high selectivity and a low detection limit of 5.6 ppb, which is much lower than the maximum contamination standard of 100 ppb in drinking water specified by the U.S. Environmental Protection Agency. Furthermore, the Tbcpon-PMMA film shows good recyclability for more than five cycles and anti-interference ability. After the introduction of the slightly soluble polymer poly(vinyl alcohol) (PVA), the Tbcpon-PVA composite film can effectively detect Cr 2 O 7 2- ions in as little as 1 min. These composite films could be potentially used as test strips for trace detection and rapid detection of Cr 2 O 7 2- ions in aqueous solution.

Three novel metal-organic assemblies (MOAs), namely, [Ag(2,4'-Hpdc)(4,4'-bpy)] n (1), [Ag(2,2'-Hpdc)(4,4'-bpy) 0.5 ] n (2), and [Cu(2,2'-Hpdc) 2 (1,4-bib)] n (3) [2,4'-H 2 pdc = 2,4'-biphenyldicarboxylic acid; 2,2'-H 2 pdc = 2,2'-biphenyldicarboxylic acid; 4,4'-bpy = 4,4'-bipyridine; 1,4-bib = 1,4-bis(1-imidazolyl)benzene] have been hydrothermally synthesized by using mixed ligands and characterized by single crystal X-ray diffraction, infrared (IR), elemental analysis and thermogravimetric analysis (TGA). The crystal structures of the three compounds indicate that the hydrogen bonding (C-HO and C-Hπ) and ππ stacking interactions play critical roles in the formation of an extended supramolecular array. The combination of C-Hπ and ππ stacking interactions endow 1 with a 3D network. 2 displays a rare 3D structure with a unique 1D structure based on an eight-membered {Ag 2 C 2 O 4 } ring and compound 3 shows a 1D chain structure, which is propagated to form an extended 3D structure only by C-Hπ hydrogen bonding. The two Ag(i)-compounds display blue emissions in the solid state at 298 K and 77 K. More significantly, compound 1 shows excellent selectivity, fast detection time (<5 min), and high sensitivity (detection limit, 9.63 nM) for Hg 2+ ions in aqueous solution due to a great enhancement of 1-luminescence, which can be attributed to Hg 2+ cation binding by a non-coordinated carboxyl group efficiently. This is a rare example of Hg 2+ detection in aqueous solution based on luminescent silver MOAs. In addition, adsorption spectra reveal the semiconductive nature (2.76 eV for 2, but not detected for 1), thus the role of the AgAg interaction in controlling the performance of the semiconductor properties is highlighted.