Hair keratin has a complex hierarchical structure, and in order to understand the correlation of the structure and the mechanical properties of hair fiber, not only must the relationships between structure and properties in the respective layers be grasped but the properties must also be grasped as being expressed by interactions among the respective layers. This paper consists of three sections, which contain (1) the architectural structure of intermediate filament (IF) protein in the hair cortex, (2) disulfide (SS) cross-linked network structures of IF and matrix protein (KAP), and (3) the effect of the time of washing after reduction on the concentration of mixdisulfide groups in permanent waved hair prepared by reduction with thioglycolic acid. In the first section, the structure models presented for IF protein in the cortex, which controls mechanical properties of hair are categorized into the tetramer antiparallel molecular model and the tetramer parallel chain model. The latter has been presented recently on the basis of the piezoelectric effect arising from the parallel chain configuration of peptide dipoles of helix molecules. Mechanical properties are also deeply related not only to the architecture of IF, but to the network structures of IF and KAP components in the cortex. In the second section, a mechanical method for analyzing the number, type, and location of SS cross-links in the keratin cortex and the results obtained to date are explained in detail with some illustrations. In the last section, a SS cross-linked network structure for permanent waved hair is proposed. The structure was determined by applying a rubber elasticity theory to the corresponding swollen hair fiber. The reformation mechanism of SS cross-links during washing after reduction is exhuastively discussed on the basis of the values of structural parameters obtained for SS bonding in the cortex. An important conclusion is derived that the reproduction of SS cross-links followed by simultaneous loss of mixdisulfide groups is due to the reverse reaction of reduction induced by removing reductant molecules from an equilibrium system by those diffusions.

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Alkyl phosphates are well known and have been commonly used for a long time in the cosmetic and detergent fields as a mild surfactant. However, many of the general industrial products of alkyl phosphate in the market are the mixtures of mono-, di- and tri-esters which do not have the specific features of mono-esters. If we use the alkyl phosphate which has highly purified mono-ester, it is expected to form a new beautiful self-assembling structure. In this study, by increasing the mono alkyl content, we tried to discover such a new functional behavior and structure using highly purified hexadecyl alkyl phosphate. Among the compounds studied, hexadecyl phosphate neutralized with L-arginine (R16MP-Arg) in an aqueous system showed characteristic solution properties and association behavior below the Krafft temperature. Spontaneous swelling of R16MP-Arg was observed below the Krafft temperature, and a gel structures composed of R16MP-Arg and water was formed without heating or shaking. This gel was identified as a thermodynamically stable “α-gel” based on the results of DSC and SAXS measurements. In this study, we revealed that highly purified mono hexadecyl phosphate with L-arginine organized a very stable α-gel structure. Cosmetics in which this α-gel is used as the base give a refreshing and smoothing sensation when applied to the skin. The unique property of R16MP-Arg is that it affords a stable gel structure even when mixed with fatty alcohol.

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Pearls have attracted attention for their elegant beauty. The unique luster of pearls is the result of complex optical phenomena caused by their multilayer structure which creates a lustrous appearance. Our aim was to apply the same lustrous effect to base makeup products. We conducted research on the influence of the optical phenomena of pearls embodied on a human face using a 3DCG simulation. At first, we were able to successfully generate facial images using a simulation of the optical phenomena of pearls such as blurring and interference. Following that, we evaluated 3DCG face images by surveying 215 women, changing each component's parameter. The images which synthesized blurring phenomena received the highest ratings for their attractiveness and visual sensory evaluation such as finishing, skin color preference and translucency. Finally, we examined the association between the optical phenomena of pearls, the visual sensory evaluation factors, and attractiveness value. We found that blurring is the most influential factor among the optical phenomena of pearls and attractiveness value. The results indicate that the influence of blurring is a valuable indicator for the development of base makeup that has a pearly appearance.

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Concerning glyceryl ascorbate, of which stability was enhanced by introducing a glyceryl group into the enediol of ascorbic acid, various glyceryl-ascorbate derivatives having various lengths of alkyl-chains were synthesized in our laboratory and investigated in terms of the relationship between the molecular structures of the derivatives and their inhibitory abilities on the melanogenesis of B16 mouse melanoma cells. As a result, 2-O-alkyl-3-O-glyceryl ascorbates, having a long alkyl-chain with not less than 12 carbon atoms, showed high melanogenesis-inhibitory effect comparable to that of hydroquinone. Furthermore it was suggested that the melanogenesis-inhibitory ability was enhanced by exchanging the functional groups between the C-2 and C-3 position of 2-O-alkyl-3-O-glyceryl ascorbate, and the high ability required the introduction of not only an alkyl-chain but also a glyceryl group.

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The orbicularis oculi muscle, one of the muscles of facial expression, influences age-related changes in the eye area. It has the role of supporting the orbital fat-pad as well as closing the eyelids. With aging, the attenuated orbicularis oculi muscle loses its ability to support the orbital fat-pad adequately, which leads to orbital fat prolapse and baggy lower eyelids. However, the mechanism of age-related attenuation of the orbicularis oculi muscle has not been clarified. The latest research has shown that IGF-1 produced by fibroblasts plays an important role in orbicularis oculi muscle formation which involves myoblast proliferation and myotube formation. Therefore, the age-related change in IGF-1 production in fibroblasts was investigated. Additionally, the effects of IGF-1 on myoblast proliferation and myotube formation were studied. Furthermore, the effect of Macroptilium atropurpureum extract on IGF-1 production in fibroblasts was investigated. As a result, IGF-1 mRNA expression in fibroblasts decreased with cellular aging. Myoblast proliferation, fusion and myotube formation were increased by the addition of IGF-1. Moreover, Macroptilium atropurpureum extract increased IGF-1 mRNA expression in fibroblasts. On the basis of these results, it was considered that the age-dependent decrease of IGF-1 production in fibroblasts causes the weakening of the orbicularis oculi muscle, which leads to baggy lower eyelids. Since IGF-1 promotes myoblast proliferation and myotube formation, Macroptilium atropurpureum extract is considered to strengthen the orbicularis oculi muscle by up-regulating the IGF-1 level in dermal fibroblasts. Therefore, Macroptilium atropurpureum extract would be an effective material for the prevention of age-related changes in the eye area.

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