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A novel function of maleic anhydride grafted polypropylene (PP) with different backbone chain-lengths was demonstrated, i.e., in controlling the cobalt morphologies (dispersed polyhedral vs. assembled chain nanostructure), crystalline structures (ε- vs. β-phase), and magnetic property (242 vs. 808 Oe) in the synthesized magnetic PP nanocomposites.

Recent outbreaks of bacterial infection leading to human fatalities have been a motivational force for us to develop antibacterial agents with high potency and long-term stability. A novel cobalt (Co) based metal-organic framework (MOF) was tested and shown to be highly effective at inactivating model microorganisms. Gram-negative bacteria, Escherichia coli (strains DH5alpha and XL1-Blue) were selected to determine the antibacterial activities of the Co MOF. In this MOF, the Co serves as a central element and an octa-topic carboxylate ligand, tetrakis [(3,5-dicarboxyphenyl)-oxamethyl] methane (TDM(8-) ) serves as a bridging linker. X-ray crystallographic studies indicate that Co-TDM crystallizes in tetragonal space group P$\overline 4$2(1) m with a porous 3D framework. The potency of the Co-TDM disinfectant was evaluated using a minimal bactericidal concentration (MBC) benchmark and was determined to be 10-15 ppm within a short incubation time period (<60 min). Compared with previous work using silver nanoparticles and silver-modified TiO(2) nano- composites over the same time period, the MBC and effectiveness of Co-TDM are superior. Electron microscopy images indicate that the Co-TDM displayed distinctive grain boundaries and well-developed reticulates. The Co active sites rapidly catalyzed the lipid peroxidation, causing rupture of the bacterial membrane followed by inactivation, with 100% recycling and high persistence (>4 weeks). This MOF-based approach may lead to a new paradigm for MOF applications in diverse biological fields due to their inherent porous structure, tunable surface functional groups, and adjustable metal coordination environments., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Co nanowires have been electroplated into porous Al2O3 templates. The crystalline structure and magnetic properties of Co nanowires of diameters 65 and 200 nm have been studied. Long single crystal Co segments with a hexagonal closed-packed (hcp) structure have been found in the 65 nm-thick nanowires. A mixture of face-centered cubic and hcp single crystal Co segments was observed in the 200 nm-thick nanowires. This finding suggests that the small template pore size favors the growth of hcp Co phase. Magnetic force microscopy measurements showed longitudinal spontaneous magnetic moments in the 65 nm-thick nanowires and transverse moments in the 200 nm-thick nanowires. [ABSTRACT FROM AUTHOR]

Heusler Ni–Mn–(Ga, In, Sn, Sb) materials can provide large magnetic-field-induced strain, giant magnetocaloric and magnetoresistance effects based on their first-order solid-state martensitic transformation. In the present work, effects of Co doping on martensitic transformation behavior in melt-spun Ni–Mn–Sn ribbons were studied by x-ray diffraction, scanning/transmission electron microscopy, and thermal analysis. Experimental results showed that both martensitic transition and austenite Curie temperatures increased linearly with Co addition to Ni49Mn39Sn12; and meanwhile, crystal structures of the martensite evolved from four-layered orthorhombic (4O) to five-layered orthorhombic (10M), and then seven-layered monoclinic (14M). The compositional dependence of the martensitic transition temperatures was well correlated with changes of valence electron concentration (e/a) and unit-cell volume of high-temperature austenite. It was proposed that both increase of valence electron concentration and shrinkage of austenite unit-cell volume with Co addition are favorable to the occurrence of martensitic transformation. In addition, the Curie temperature of austenite increases with Co addition, which was ascribed to the enhancement of ferromagnetic exchange interaction. [ABSTRACT FROM PUBLISHER]

A high-pressure optical zone-melting technique was employed to grow a Mn-rich Heusler Mn 50 Ni 37 Co 3 In 10 unidirectional crystal in the present study. It was found that the Co-doped Mn 50 Ni 37 Co 3 In 10 unidirectional crystal showed a low magnetic hysteretic loss and a widened working temperature interval in the vicinity of the martensitic transformation. The inverse magnetic entropy change (∆ S M ) reached 7.84 Jkg −1 K −1 around 237.5 K under a magnetic field change of 30 kOe, and the corresponding effective refrigeration capacity ( RC eff ) was about 127.2 Jkg −1 . The experimental results demonstrated a high potential to develop high-performance Mn-rich Heusler Mn–Ni–In magnetocaloric materials by means of Co doping in combination with the high-pressure optical zone-melting fabrication technique. [ABSTRACT FROM AUTHOR]

In order to improve lithium storage capacity and cycle stability of the electrode materials, the combination of the active material and graphene is an effective way. Reduced graphene oxide (rGO) film on Ti substrate is obtained in an aqueous graphene oxide solution using a two-electrode constant voltage electrodeposition system. Then the rGO film on Ti substrate is used as working electrode to assemble lithium-ion batteries and discharged to 0.01 V. The discharged rGO film further reacts with cobalt ions in the cobalt acetate aqueous solution to fabricate the cobalt oxide (CoO)/rGO-precursor, and subsequently the CoO/rGO-700 composite is obtained by calcining the precursor at 700 °C under N 2. Different measurements are conducted to evaluate the samples. The CoO/rGO-700 composites are further used as electrode material of lithium-ion batteries, which deliver an initial capacity of 1290.6 mAh·g−1 at 100 mA·g−1. For the first time, the synthetic method reported in this work can be extended to the synthesis of other metal or oxide/rGO composites. Unlabelled Image • rGO film is successfully prepared by an electrodeposition method. • CoO nanoparticles are anchored on the discharged-graphene film successfully. • The CoO/rGO-700 composites deliver a reversible capacity of 1290.6 mAh·g−1 at 100 mA·g−1. [ABSTRACT FROM AUTHOR]