198 JOURNAL OF COSMETIC SCIENCE The factors that are conventionally suggested as be- ing responsible for the dark circles around the eyes include the retention of blood and poor circulation. In actual fact, however, reports of measurements of blood flow around the eyelid are scarce, and the literature is silent on research into any direct rela- tionship between dark circles and the kinetics of blood flow. In the present work, we used a laser Doppler flowmeter and depthprobe to measure at four different depths, the hemodynamic parameters of blood flow (Flow), mass (Mass), and velocity (Vel.), in a bid to elucidate the circulatory kinetics at the site of formation of dark circles. We also sought to shed more light on the phenomenon of dark circles by measuring skin color and skin surface temperature at the same site. In the periphery of the internal canthus, where dark circles are more readily formed, we found that blood mass (Mass) was high and blood velocity (Vel.) was slow at the skin sur- face. We also demonstrated that the retention of blood, conventionally regarded as occurring at the site of formation of dark circles, can be characterized by greater blood mass (Mass) and slower blood ve- locity (Vel.). As well, the skin brightness (L*) was low in the periphery of the internal canthus, and was correlated with blood mass (Mass), suggesting that retention of blood in the surface of the skin may be a significant factor in the development of dark circles. The Relationship between Moisture Content of Human Fingernails and the Mechanical Proper- ties of the Fingernail (Part 3) Tooru Sugawara, Mizue Kawai, Toshiyuki Suzuki, Cosmetic Research Laboratories, Kao Corporation It is well known that nail damages such as yellow- ing, split nails and peeled nails (onychoschisis) is caused by continuous use of nail enamel for a long period. Within serious nail damages, we aimed at split nails and peeled nails and basically investigated the effect of organic solvents on fingernail moisture content and the mechanical properties to make clear the factors affecting those nail damages. As a result, the change in fingernail volume of fingernail dipped in water was much more considerable than that dipped in organic solvents. It is suggested that the fingernails dipped in organic solvents is harder and brittler than the fingernails dipped in water from the result of E' and tan of the fingernails dipped in water and organic solvents. Moreover we proposed the mechanism of the split nails caused by organic solvents. Optical Characteristic of Zirconia Coated Spherical Complex Silica and Application to Cosmetic Foundations Motoaki Ito, Noboru Nagatani, Masahiko Asahi, Toshiyuki Suzuki, Skin Care Research Laboratories, Kao Corporation One of the important functions for cosmetic foun- dations is to conceal pores of the skin. In order to search for powders that can both conceal pores and provide a natural finish, we evaluated various pow- ders by measuring the chrominance and luminosity. As a result, the zirconia coated spherical silica in- cluding titania (TSZ) was the most effective powder. The reasons for the effectiveness of TSZ were as- sumed as follows: (1) the optical characteristic due to the complex structure consisting of a high refrac- tive index inclusion which provides coverage, and a moderate refractive index substance which covers the outmost layer (2) the spherical shape allowing it to be applied in the pores selectively. By applying TSZ to cosmetic foundations, we obtained products that conceal pores effectively and yet offer natural finish.