A clear correlation between defect‐related emissions and the magnetization of ZnO nanorods synthesized by a one‐step aqueous chemical method is demonstrated. The relative contribution of the emission bands arising from various types of defects is determined and found to be linked with the size of the nanorods and annealing conditions. When the size of the nanorods and the annealing temperature are increased, the magnetization of pure ZnO nanorods decreases with the reduction of a defect‐related band originating from singly charged oxygen vacancies ($V_{\rm o}^ +$). With a sufficient increase of annealing temperature (at 900 °C), the nanorods show diamagnetic behavior. Combining with the electron paramagnetic resonance results, a direct link between the magnetization and the relative occupancy of the singly charged oxygen vacancies present on the surface of ZnO nanorods is established.

Field emission (FE) has been extensively explored from various exotic low dimensional carbon nanomaterials, such as amorphous carbon films, 1 single and multiwalled carbon nanotubes (CNTs), 2 tubular graphitic cones, 3 vertically aligned nanowalls, 4 few-layered graphene (FLG) nanoflakes, 5,6 and, more recently, from doped and pristine graphene. 7,8 Graphene, a two-dimensional monatomic plane layer of hexagonally arrayed sp 2-hybridized carbon atoms forms the backbone of all the above-mentioned carbon nanostructures. 9 The highly desirable properties of graphene, such as atomic thickness, excellent electrical conductivity, and high aspect ratio, make it an ideal candidate for field emission applications. 7-9 Also, as compared to CNTs, the presence of a large number of edges may render graphene superior for electron tunneling. 7 Although FE in CNTs is highly efficient, it has been shown that heteroatom doping by elements, such as nitrogen, can further reduce the effective tunneling potential barrier, thereby reducing the turn-on field and significantly increasing the electron emission current. 10,11 Nitrogen acts as an electron donor in CNTs because it has five valence electrons and causes a shift in the Fermi level (E F) to the conduction band and increases the electron density of states (DOS). In the case of graphene, theoretical studies have shown that substitutional heteroatom doping can modulate the band structure of graphene, leading to a metal-semiconductor transition, thereby expanding the applications of graphene. 12,13 Although Malesevic et al. 5 and Qi et al. 6 have shown the field emission behavior of pristine and Ar plasma-treated FLG nanoflakes, respectively, to the best of our knowledge, until now, there ' EXPERIMENTAL SECTION The synthesis of FLGs was carried out in a SEKI MPECVD deposition system, equipped with a 1.5 kW, 2.45 GHz microwave source. The substrates used were bare n-type heavily doped Si wafers (resistivity < 0.005 Ω cm) (10 mm  10 mm). Prior to growth, the substrates were pretreated with N 2 plasma at 650 W at 40 Torr while the substrate temperature was maintained at 900°C. Synthesis was then carried out using CH 4 /N 2 (gas flow

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Zinc ferrite films were deposited on fused quartz substrate at different temperatures using pulsed laser ablation (PLA) and rf sputtering. X-ray diffraction indicated that all the films were single phase ZnFe2O4 with grain growing in the range of 8–80nm with substrate temperature. The nanocrystalline films were found to be magnetic and the spontaneous magnetization showed a strong dependence on the grain size, dropping sharply for films with larger grains. A PLA thin film deposited in vacuum at 500°C exhibited a room temperature magnetization value of 5560G.

By exploiting the presence of abundant carboxylic groups (-COOH) on graphene oxide (GO) and using EDC-NHS (1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride-N-hydroxysuccinimide) chemistry to covalently conjugate protein molecules, we demonstrate a novel electrochemical immunosensor for detection of antibody-antigen (Rabbit IgG-AntiRabbit IgG) interactions. The interactions were verified using Electrochemical Impedance Spectroscopy (EIS). Although GO is known to be a poor conductor, the charge transfer resistance (R P) of a GO modified glassy carbon electrode (GCE) was found to be as low as 1.26 U cm 2. This value is similar to that obtained for reduced graphene oxide (RGO) or graphene and an order of magnitude less than bare GCE. The EIS monitored antibody-antigen interactions showed a linear increase in R P and the overall impedance of the system with increase of antibody concentration. Rabbit IgG antibodies were detected over a wide range of concentrations from 3.3 nM to 683 nM with the limit of detection (LOD) estimated to be 0.67 nM. The sensor showed high selectivity towards Rabbit IgG antibody as compared to non-complementary myoglobin. RGO modified GCE showed no sensing properties due to the removal of carboxylic groups which prevented subsequent chemical functionalization and immobilization of antigen molecules. The sensitivity and selectivity achievable by this simple label free technique hint at the possibility of GO becoming the electrode material of choice for future electrochemical sensing protocols.