P-N heterojunction NiO/ZnO nanowire based electrode for asymmetric supercapacitor applications.

Nickel-based oxides are selected for their inexpensive cost, well-defined redox activity, and flexibility in adjusting nanostructures via optimization of the synthesis process. This communique explores the field of energy storage for hydrothermally synthesized NiO/ZnO nanowires by analysing their capacitive behaviour. The p-type NiO was successfully built onto the well-ordered mesoporous n-type ZnO matrix, resulting in the formation of p-n heterojunction artefacts with porous nanowire architectures. NiO/ZnO nanowire-based electrodes exhibited much higher electrochemical characteristics than bare NiO nanowires. The heterojunction at the interface between the NiO and ZnO nanoparticles, their specific surface area, as well as their combined synergetic influence, are accountable for the high specific capacitance (Cs) of 1135 Fg-1at a scan rate of 5 mV s-1. NiO/ZnO nanowires show an 18% dip in initial capacitance even after 6000 cycles, indicating excellent capacitance retention and low resistance validated by electrochemical impedance spectroscopy. In addition, the specific capacitance, energy and power density of the solid state asymmetric capacitor that was manufactured by employing NiO/ZnO as the positive electrode and activated carbon as the negative electrode were found to be 87 Fg-1, 23 Whkg-1and 614 Wkg-1, respectively. The novel electrode based on NiO/ZnO demonstrates excellent electrochemical characteristics all of which point to its promising application in supercapacitor devices.

Surface properties and biocompatibility of nanostructured TiO2 film deposited by RF magnetron sputtering.

Nanostructured TiO2 films are deposited on a silicon substrate using 150-W power from the RF magnetron sputtering at working pressures of 3 to 5 Pa, with no substrate bias, and at 3 Pa with a substrate bias of -50 V. X-ray diffraction (XRD) analysis reveals that TiO2 films deposited on unbiased as well as biased substrates are all amorphous. Surface properties such as surface roughness and wettability of TiO2 films, grown in a plasma environment, under biased and unbiased substrate conditions are reported according to the said parameters of RF power and the working pressures. Primary rat osteoblasts (MC3T3-E1) cells have been cultured on nanostructured TiO2 films fabricated at different conditions of substrate bias and working pressures. The effects of roughness and hydrophilicity of nanostructured TiO2 films on cell density and cell spreading have been discussed.

Harmonic mode locking of bound solitons.

We systematically investigate the passive harmonic mode locking (HML) of the bound states of two solitons in a fiber laser that has been mode locked by nonlinear polarization rotation (NPR). The experiment shows that the stable HML state of the bound solitons (BSs) with a fixed and discrete separation is obtained. The repetition rate changes by increasing the pump power and slightly altering the polarization state in the cavity. The dynamic is similar to the HML of a single-pulse operation. In our experiment, the repetition rate can be turned from the fundamental mode locking up to ninth-order HML when the pump power is increased from 168 to 476.1 mW. Once the BSs are obtained, their separation is fixed at 1.5 ps, regardless of the HML order. Under the direct BS interaction, the BS trains are very stable and easily reproducible. This HML behavior of BSs confirms that the BS is another intrinsic feature of the laser, except for the single soliton.