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The purpose of this study was to investigate how the characteristics of a poly-L-lactic acid mini-plate changed with dynamic loading in an environment with hydrolytic degradation.We prepared a mandible osteosynthesis model with specimen poly-L-lactic acid mini-plates to simulate sagittal splitting ramus osteotomy. The model was then subjected to dynamic loading, and changes in specimen shape and surface quality were observed. Specimen bending strength was then measured, and degree of hydrolytic degradation estimated. Statistical studies included an analysis of variance (ANOVA).Neither dynamic loading nor degree of load clearly affected degree of hydrolytic degradation. The specimens maintained their original shape and bending strength for up to 4 weeks with dynamic loading of 40 N or less in an environment with hydrolytic degradation. However, at 8 weeks, under the same conditions, the specimens showed cracks or fractures, or both, together with a clear decrease in bending strength.The results suggest that dynamic loading causes cracking in a poly-L-lactic acid mini-plate, and that growth of those cracks decreases bending strength over time, leading to fatigue fracture.--2

In the present study, the comfort properties of knitted fabrics made from a two-ply yarn comprising a paper yarn and a cotton yarn were investigated. The objective was to elucidate the characteristics of paper yarn in comparison with cotton in terms of the design and development of comfortable and ecofriendly textiles that directly contact the skin. A two-ply yarn comprising a paper yarn made from abacá and a cotton yarn was prepared. Five fabrics with different proportions of paper were prepared by changing the knitting ratio of the two-ply yarn to a 100% cotton yarn. The mechanical properties (tensile, shearing, bending, compression, surface, contact area, and air permeability properties) and various thermal and moisture-transport properties of the fabric samples were determined. Those investigations revealed that the surface roughness increased, the friction coefficient decreased, the contact area decreased (in both the dry and wet state), the air permeability increased, the thermal conductivity increased, and the moisture diffusivity increased as the proportion of paper yarn increased. The fabric consisting of only the two-ply yarn was noticeably stiffer than the fabrics that also contained a pure cotton yarn. The results suggest the possibility of developing clothes that feel comfortable next to the skin, even when wet (e.g. underwear and socks) by knitting the two-ply yarn in a well-balanced ratio with cotton yarns.

The purpose of this study is to evaluate the wearing comfort of uniform-shirts and to investigate the suitable value for the preset temperature of a i r c o n d i t i o n e r s t h o r o u g h m e a s u r i n g m a t e r i a l p r o p e r t i e s a n d psychophysiological responses. The uniform shirt was made of cellulose materials such as rayon and tencel for wearing in hot conditions like summers in Japan. Material properties measurement were made according to Kawabata Evaluation System (KES), Japan Industrial Standards (JIS) and Moisture Management Tester (MMT). Physiological response measurements were electrocardiogram (ECG), respiration, skin temperature and the humidity inside the clothes. Psychological response measurements were by semantic differential method and ranking method. We concluded that the uniform shirts made of rayon are comfortable even in hot conditions like summer in Japan. 29˚C as the temperature setting of air conditioners is too hot for people. Respiration seems to be an important factor for evaluation of wearing comfort.

The purpose of this study is to evaluate the wearing comfort of polypropylene (PP) clothes thorough measuring material properties and physiological and psychological responses. PP fiber has low thermal conductivity, is hydrophobic, and has a lighter specific gravity. These features are useful in a clothing material. PP fibers have attracted much attention in the apparel industry. We assumed that PP is a good material for a comfortable warm-up underwear, since PP clothes would prevent the decreases in skin surface temperature when perspiring. Material properties measurement were made according to Kawabata Evaluation System (KES) and Japan Industrial Standards (JIS). We examined the characteristics of the samples, and then narrowed down the samples by cluster analysis for the clothing experiment. After that, we conducted an experiment measuring the physiological and psychological responses in the state of wearing a sample while warming up the lower limb. Physiological response measurements were electrocardiogram (ECG), respiration, and the temperature and humidity in the clothes. Psychological response measurements were by semantic differential method and ranking method. We calculated LF/HF as an indicator of autonomic nerve activity by ECG. Then we created a comfort indicator called SAC from the LF/HF and humidity in clothes. Order by ranking method corresponds with ranking by SAC. We concluded that PP clothes are comfortable when perspiring.