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Large quantities of monodispersed single-crystal rhombic dodecahedral (RD) Fe 3 O 4 nanocrystals (NCs) bounded by high-energy {110} facets were prepared by using a one-pot toluene−water two-phase interfacial reaction method. By adjusting the Fe(acac) 3 concentration and the volume of hydrazine hydrate, their sizes could be controlled in the range from 60 to 100 nm. The formation of these RD Fe 3 O 4 NCs with exposed highenergy {110} surfaces might be the result of selective stabilization of such unstable facets by the C 17 H 33 COO − based on FT-IR analysis. The magnetic measurement revealed that the saturation magnetization (M s ) of the RD Fe 3 O 4 NCs was 85 emu/g at room temperature. When used as peroxidase mimetics, the prepared RD Fe 3 O 4 NCs showed excellent peroxidase-like catalytic activity toward oxidation of the substrate 3,3′,5,5′-tetramethylbenzidine and degradation of the aniline compound methylene blue dye in the presence of H 2 O 2 . When tested as anode materials for lithium-ion batteries, these as-obtained RD Fe 3 O 4 NCs showed a high initial discharge capacity of 1147 mA h g −1 at the current density of 0.2 C, a good cycle performance (362 mA h g −1 at 0.2 C after 100 cycles and 191 mA h g −1 at 1 C up to 130 cycles), and good rate capability at high current rates of 1−4 C.

We report a theoretical study of electron transport along helical molecules under an external electric field, which is perpendicular to the helix axis of the molecule. Our results reveal that the topological states could appear in single-helical molecule and double-stranded DNA in the presence of the perpendicular electric field. And these topological states guarantee adiabatic charge pumping across the helical molecules by rotating the electric field in the transverse plane and the pumped current at zero bias voltage is quantized. In addition, the quantized current constitutes multiple plateaus by scanning the Fermi energy as well as the bias voltage, and hold for various model parameters , since they are topologically protected against perturbations. These results could motivate further experimental and theoretical studies in the electron transport through helical molecules, and pave the way to detect topological states and quantized current in the biological systems. Introduction.-Helix structures are ubiquitous both in the biological world[1-3] and for synthetic materials[4-6]. The electron transport along helical molecules, such as DNA and α-helical protein, has been receiving much attention among the scientific communities[7-17], because this subject can enrich our knowledge regarding the electronic properties of low-dimensional systems due to the unique helix structure and provides valuable information for understanding the biological processes in living organisms[18-20]. It was reported by direct charge transport experiments that double-stranded DNA (dsDNA) could exhibit fascinating physical phenomena, such as the proximity-induced superconductivity[21], the negative differential resistance[22], and the piezoelectric effect[23]. Additionally, it was shown that both dsDNA and α-helical protein can behave as electric field-effect transistors[24-27] and as efficient spin filters[28-35].

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Highly photoluminescent carbon nanoparticles with a quantum yield of 37.40% were directly synthesized by a simple hydrothermal treatment of oatmeal in pure water without using any surface passivation and oxidizing agents. Due to the bright fluorescence, high photo-stability, low toxicity and good biocompatibility, the as-prepared carbon nanoparticles are demonstrated to be excellent probes in bio-imaging.