What is the fine-grained topic of the following text: The aim of the study is to predict how the optical properties of the superficial layer of the human skin (stratum corneum) can be modified by means of nanoparticles, assuming that these particles are spheres and do not aggregate (this is achieved by application of some modern treatment techniques). Only return the topic.
Predicting modifications in optical properties of human skin's superficial layer through nanoparticle application.