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Abstract: A composite coating which could control drug release and biocorrosion of magnesium alloy stent materials WE42 was prepared. This composite coating was fabricated on the surface of the micro-arc oxidation (MAO) film of the magnesium alloy, WE42, by mixing different degrees of cross-linked gelatin with well-dispersed poly(dl-lactide-co-glycolide) (PLGA) nanoparticles. The PLGA nanoparticles were prepared by emulsion solvent evaporation/extraction technique. Nano ZS laser diffraction particle size analyzer detected that the size of the nanoparticles to be 150–300nm. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) was used to analyze the morphology of the nanoparticles and the composite coating. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were used to evaluate the corrosion behavior of the composite coating. Drug release was determined by ultraviolet–visible (UV–vis) spectrophotometer. The corrosion resistance of the composite coating was improved by preventing the corrosive ions from diffusing to the MAO films. The drug release rate of paclitaxel (PTX) exhibited a nearly linear sustained-release profile with no significant burst releases. [Copyright &y& Elsevier]

Highlights • Ultrafine porous carbon/MnO 2 nanowires were expected to shorten the ion diffusion path. • The carbon aerogel derived from methyl cellulose provides a cost-consuming system. • The hierarchical structure serves as stable framework to reduce the agglomeration. • The composite can be stamped into arbitrary patterns to be applied in micro-devices. Abstract A green and scaled-up strategy has been successfully employed to fabricate asymmetric supercapacitors (ASC) in conjunction with high energy density as well as highly efficient electrode materials. In this study, a B, N-dual doped porous carbon aerogel negative and a novel ultrafine nanowire positive composite, composed of manganese oxide (MnO 2) core and carbon aerogel shell, were proposed. Methyl cellulose (MC) is spaciously available and the affluent hydroxyl groups on the molecular chains are conductive to trigger supramolecular assemble process to form self-crosslinking hydrogel. And then the hydrogel was dried and carbonized to obtain the B, N-dual doped porous carbon aerogel (BN-MC), with the specific area of 989.8 m2 g−1. Subsequently, a facile and efficient hydrothermal system, introduced to synthesize BN-MC/α-MnO 2 composite, is prone to achieve hybrid nanowires with an average width of ∼15 nm. The prepared 0.1BN-MC/MnO 2 -8 sample (0.1 M NH 4 HB 4 O 7 doping agent and 8 mg BN-MC addition) exhibits highest electrochemical behavior, whose capacitance is up to 338 F g−1 at 1 A g−1. That is ascribed to the well-dispersed α-MnO 2 nanowires and uniformly cladding BN-MC shell. The ASC, assembled with BN-MC/MnO 2 and BN-MC, significantly enhances energy density reaching to 27.75 Wh kg−1 at a power density of 1.35 kW kg−1 operating under 1.8 V voltage window. This ASC also shows superior cycling stability for maintaining 95.6% initial capacitance after 2000 cycles. What's more, the BN-MC/MnO 2 can be stamped into arbitrary patterns in seconds. This provides a new rapid prototyping technology for fabricating flexible and portable micro-supercapacitor devices. [ABSTRACT FROM AUTHOR]

Nanoscale zero-valent iron (nZVI) has high removal efficiency and strong reductive ability to organic and inorganic contaminants, but concerns over its stability and dispersity limit its application. In this study, nZVI was modified with sulfide to enhance Cd(II) removal from aqueous solutions. TEM and SEM analyses showed that sulfide-modified nZVI (S-nZVI) had a core-shell structure of nano-sized spherical particles, and BET results proved that sulfide modification doubled the specific surface area from 26.04 to 50.34 m 2  g −1 and inhibited the aggregation of nZVI. Mechanism analysis indicated that Cd(II) was immobilized through complexation and precipitation. Cd(II) removal rate on nZVI was only 32% in 2 h, while complete immobilization could be achieved in 15 min on S-nZVI, and S-nZVI with an optimal S/Fe molar ratio of 0.3 offered a cadmium removal capacity of about 150 mg g −1 at pH 7 and 303 K. The process of Cd(II) immobilization on S-nZVI was fitted well with pseudo-second-order kinetic model, and the increase of temperature favored Cd(II) immobilization, suggesting an endothermic process. The presence of Mg 2+ and Ca 2+ hindered Cd(II) removal while Cu 2+ did the opposite, which led to the order as Cu 2+  > control > Mg 2+  > Ca 2+ . The removal rate of 20 mg L −1 Cd(II) maintained a high level with the fluctuation of environmental conditions such as pH, ion strength and presence of HA. This study demonstrated that S-nZVI could be a promising adsorbent for Cd(II) immobilization from cadmium-contaminated water. [ABSTRACT FROM AUTHOR]

In this study, a novel bamboo activated carbon (BAC) with ethylene diamine tetraacetic acid (EDTA) functionality was prepared by direct grafting in the presence of tetraethyl orthosilicate (TEOS) as a crosslinking agent. The BAC@SiO 2 -EDTA was characterized by SEM, TEM, TGA, FTIR, XPS and its adsorption property for removal of Pb(II) and Cu(II) under various experimental conditions was also investigated. The characterization results reflected that EDTA was successfully assembled on the surface of the BAC and average pore size increased from 4.10 to 4.83 nm as BAC grafted with EDTA. Adsorption data fitted very well in Langmuir isotherm model and pseudo-second-order kinetic model. As compared with the raw BAC, the maximum adsorption capacities of BAC@SiO 2 -EDTA for the Pb(II) and Cu(II) increased from 45.45 to 123.45 mg g −1 and from 6.85 to 42.19 mg g −1 , since the existence of EDTA on modified BAC promoted the formation of chemical complex. The removal of heavy metal ions mainly depended on the complexation with EDTA and the electrostatic attractions with negatively charged surface of BAC@SiO 2 -EDTA. The adsorption of Pb(II)/Cu(II) on the BAC@SiO 2 -EDTA was pH dependent and pH 5–6 was considered an optimum. However, lower temperature favored the adsorption and the maximum adsorption was recorded at 20 °C. In addition, BAC@SiO 2 -EDTA had an excellent reusability with about 40% decline in the adsorption capacity for Pb(II) after fifth reuse. Insignificant influences of co-existing cations and natural organic matter (NOM) were found on the adsorption of Pb(II) and Cu(II). All the results demonstrate that BAC@SiO 2 -EDTA is a potential adsorbent for metal ions in wastewater. [ABSTRACT FROM AUTHOR]

The novel Sn-Cu nanotubes enveloped in three-dimensional (3D) hierarchical polyaniline (PANI) hydrogel (Sn-Cu/PANI) were successfully prepared as a high performance anode for lithium-ion battery. The binder-free electrode exhibits reversible capacity of 548 mA h g −1 after 500 cycles and admirable rate capacity even up to 5000 mA g −1 . The exceptional electrochemical performance of Sn-Cu/PANI hydrogel could be attributed to the unique structure: (1) The inactive Cu matrix in binary Sn-Cu compounds and the tubular construction conduce to relieve the volume swing; The high porosity originated from galvanic replacement reaction accelerates ions transmission, which contributes to rapid charging and discharging. (2) The 3D porous PANI framework offers a continuous electron and lithium ions transport network among the whole electrode; the hierarchical PANI serves as mechanical support to accommodate the stress related to the large volume change of Sn-Cu nanotubes, thus reducing the risk of electrode pulverization. [ABSTRACT FROM AUTHOR]

A novel reversible interaction in polymeric nanoparticles is used to induce hollow Sn 4+ -MOPs. Then ultrafine Sn nanoparticles uniformly embedded in shell of N-doped hollow carbon spheres is successfully synthesized by pyrolysis of the Sn 4+ -MOPs precursor. In this architecture, the N-doped carbon shells can effectively avoid the direct exposure of embedded Sn nanoparticles to the electrolyte and efficiently accommodate the volume change of Sn nanoparticles. Furthermore, the hollow structure of carbon sphere can prevent Sn nanoparticles aggregation over repeated cycling and shorten the diffusion path of both electrons and ions. As a consequence, this N-doped hollow Sn/C anode delivers a reversible capacity of 606 mA h g −1 at a current density of 0.2 A g −1 after 250 cycles and a reversible capacity of 221 mA h g −1 even at a much higher current density of 10 A g −1 , which are much better than those of pure Sn nanoparticles. The desirable cyclic stability and rate capability were attributed to the unique architecture that provided fast pathway for electron transport and simultaneously solved the major issues of Sn-based anodes, such as pulverization, aggregation and loss of electrical contact. [ABSTRACT FROM AUTHOR]

In this study, EDTA-functionalized Fe 3 O 4 (Fe 3 O 4 @SiO 2 -EDTA) was prepared by silanization reaction between N-(trimethoxysilylpropyl) ethylenediamine triacetic acid (EDTA-silane) and hydroxyl groups for Pb(II) and Cu(II) removal from aqueous solutions. Fe 3 O 4 @SiO 2 -EDTA composites were characterized using SEM, TEM, EDX, FTIR, XPS, TGA and saturated magnetization techniques. Maximum Pb(II) adsorption capacity was found to be 114.94 mg g −1 with SiO 2 /EDTA molar ratio of 2.5:1. The adsorption rate was significantly fast and the equilibrium was reached within 10 min. The optimum pH was recorded to be 5.0. The maximum adsorption capacity of the studied heavy metal ions calculated by Langmuir model followed the order: Cu(II) (0.58 mmol g −1 ) > Pb(II) (0.55 mmol g −1 ) ≈ Ni(II) (0.55 mmol g −1 ) > Cd(II) (0.45 mmol g −1 ). Moreover, Pb(II) and Cu(II) adsorption capacities were not significantly affected by co-existing cations and NOM. These results suggested that this adsorbent can be considered as a promising adsorbent to remove Pb(II) and Cu(II) from wastewaters. [ABSTRACT FROM AUTHOR]

Polymethyl methacrylate (PMMA)-coated hollow Sn–Co nanospheres (Sn–Co@PMMA) with superior electrochemical performance had been synthesized via a facile galvanic replacement method followed by an in situ emulsion polymerization route. The properties were investigated in detail and results show that the hollow Sn–Co nanospheres were evenly coated with PMMA. Benefiting from the protection of the PMMA layers, the hollow Sn–Co@PMMA nanocomposite is capable of retaining a high capacity of 590 mAh g −1 after 100 cycles with a coulomb efficiency above 98%, revealing better electrochemical properties compared with hollow Sn–Co anodes. The PMMA coating could help accommodate the mechanical strain caused by volume expansion and stabilize the solid electrolyte interphase (SEI) film formed on the electrode. Such a facile process could be further extended to other anode materials for lithium-ion batteries. [ABSTRACT FROM AUTHOR]