For this study, we synthesized diamond using the hot tube chemical vapor deposition （CVD） method, for which the filament of thermal filament CVD is replaced by cylindrical metal foil. Effects of the tube length, total gas flow rate, and distance between the gas outlet and the substrate were investigated when using this method. Diamond and nanocrystalline diamond （NCD） films were obtained with tube lengths greater than 10 mm. Additionally, longer tube lengths were associated with increased deposition rates and decreased film quality, suggesting enhanced gas decomposition. The deposition rate increased along with the total flow rate. At 1500 ℃ tube temperature, the maximum deposition rate of 6 μm/h was achieved under conditions of 3 mm substrate distance and 20 mm tube length. The intensity ratio of the diamond peak to the non-diamond peak, calculated from the Raman spectrum, reached a maximum value of 3.2 for 10 mm tube length and 10 mm substrate distance.

Using smartphone and color information software, we conducted plating solution analysis and practical evaluation. For a nickel plating solution, the conventional volumetric analysis result was 64.23（g/L）. The result obtained by our developed method was 63.91（g/L）. These findings confirm that this method yielded results similar to those obtained by volumetric analysis.

Porous-type anodic oxide with re-entrant structures formed by two distinct anodizing processes suppressed the delay of boiling initiation. Even after long-term boiling, the nanostructured oxide surface maintained its structure. Moreover, the boiling cooling performance of hydrofluoroether-7100 was equal to that before the test.