particularly at the molecular level,
remains largely not investigated. From this angle, the positron method utilizes positronium as its de- fect probe, which due to its small size (2 Å) and penetrability can directly characterize the microstructural damage to the cortex re- gion. This special feature of PALS technique, exploited in this study, could be the basis for an important and unique method of product testing and evaluation in the cosmetic industry.