The effects of the grain size of WQ on WO3-based sensor for NOx were investigated. By hydrolyzing ammonium paratungstate with hot nitric acid in solution and calcining the resulting precipitate in air at prescribed temperatures in the range of 300 to 600~ the mean crystallite sizes (D) of WQ were varied in the range of 16 to 57 nm. The sensitivities of the WO3 sensor elements to NO2 (10 ppm) as well as to NO (200 ppm) remained independent of D down to D = 33 nm, below which the sensitivities increased steeply with a decrease in D, reaching at D = 25 nm the sensitivity values three to four times as large as those for D > 33 nm.

Feasibility of two-dimensional propagation of the domain wall (DW) was investigated by micromagnetic simulations. Successful bit-by-bit propagation of the DW was demonstrated in a designed meandering magnetic strip with periodic material parameter modulation, used as DW pinning sites (PSs). The DW was successively shifted along the straight part and around the corner with a spin polarized current pulses with 1 ns-width, 3 ns-interval and same amplitude. A practical current amplitude margin (30 % of mid value) was achieved by analyzing the energy landscape around the meandering corner and optimizing the location of the PSs, which energy barrier height assures a thermal stability criterion (>60 kBT).