A nanostructured thin film of NiO with thickness (1250 ± 30) nm was synthesized using the RF-reactive planer magnetron sputtering technique over a cleaned glass substrate. Structural analysis of the nanostructured NiO films was conducted utilising the XRD method, and the films were found to have a polycrystalline nature with a preferred (200) plane reflection at the angle 2θ equal to 43.35ᵒ. The optical measurement for NiO thin films manifested the transmittance, the energy band gap and the absorption coefficient in the ultraviolet and visible regions. A scanning electron microscope (SEM) was used to analyses the surface morphology of the NiO thin film sample. The ability of nanostructured NiO thin films to sense different NO₂ gas concentrations in terms of the time working was studied and reported. The nanostructured NiO film had better sensitivity at the gas ratio of 350 ppm and the operating temperature 150ᵒC.

Thin-walled parts are commonly used in the aerospace sector. However, there are serious machining challenges, such as deflection, deformation and vibration. The final thin-walled component machining will deteriorate the dimensional accuracy and surface quality. This is due to the vibration and deformation that occurs during flexible milling of thin-walled structures since the workpiece rigidity is lower than the cutting forces of the milling cutter. The gradual reduction of the thin-wall thickness during the end milling process results in significant deflections and deformations due to its low rigidity and low stiffness. In recent years, different approaches have been used to deal with these challenges. This paper presents a new technique for machining thin-walled parts with great accuracy, excellent flatness and straightness properties, and good productivity. The authors have developed a new milling technique using simultaneous double-sided cutter milling, in which synchronized vertical double end milling cutter finishes and machines both thin-wall surfaces simultaneously. This produces lower cutting thrust forces on the walls, as each cutting thrust force cancels out the other. The rotation of the milling machine spindle is transmitted to the double cutters by an in-house double-axis adapter. Surface errors are minimized, flatness and straightness properties are significantly improved, and the thin-wall deflection can be neglected, as shown in our results. The thin wall can be finished in only one pass, and a 50% reduction in machining time can be achieved. In addition, thin-wall flatness is improved about two to three times, compared to the conventional milling procedure.