At present, China's major cities are booming in the construction of rail transit projects. Because of its unparalleled advantages, shield method has been widely used in the construction of rail transit tunnels.

For electronic and photoelectric applications, solar cells convert energy from sunlight to electricity. Graphene has excellent charge transfer performance. Electrons move in graphene at 1 / 30 of the speed of graphite - much faster than other materials. This shows that graphene can be used in solar cells, but graphene also has a major disadvantage, which hinders this application - its ultra short life excited electrons are only about one picosecond (one millionth of a second).

Rare earth trivalent ions have rich 4f energy level configuration, and their fluorescence characteristics are greatly affected by the crystal field environment and the symmetry of the lattice. At present, many scholars use the small size effect of semiconductor nano materials (ZnO, TiO₂) and lattice sensitization to improve the optical properties of rare earth trivalent ions, which are widely used in biological fluorescent probes, optical devices and new luminescent materials.

With the continuous exploitation of tungsten resources, scheelite and medium ores with high impurity content become the main sources of tungsten smelting raw materials. In the existing technology, the smelting of Scheelite Concentrate and medium ore generally adopts the high alkali pressure boiling technology, and the alkali input is generally 2.8-4 times of the theoretical amount. The quality ratio of excess NaOH and WO₃ in the coarse sodium tungstate solution obtained after the alkali pressure boiling slurry is 0.7-1.2. If not recovered, it will not only bring adverse effects on the subsequent process, but also consume sulfuric acid to neutralize it before discharging.