With the further development of China's reform and opening up, buildings are getting higher and higher. In these high-rise buildings, most of the windows are floor to floor windows to increase the indoor lighting. However, because these glasses generally do not have the function of adjusting the light, if the residents want to adjust the light, they usually install a group of curtains on the windows, and adjust the opening and closing of the windows to adjust the light. However, by installing curtains to adjust the light, not only the process increases and increases the cost, but also the users need to manually adjust the opening and closing of windows, which is not convenient.

Nano violet tungsten oxide has optical properties and strong absorption ability in near infrared region. Therefore, it can be used as a photothermal conversion material and used in cancer treatment. Nano violet tungsten oxide has a very high application value in the preparation of near infrared photothermal medicine.

Under an atmosphere of H₂ or Ar, WS₂ nanotube with small diameter and few layers can be successfully synthesized by heating W₁₈O₄₉ nanowire and sulfur powders at 840°C. During the preparation process, W₁₈O₄₉ nanowire is first prepared from WCl₆ and ethanol.