Auxetic Photonic Patterns with Ultrasensitive Mechanochromism.

Photonic crystals with mechanochromic properties are currently under intensive study to provide intuitive colorimetric detection of strains for various applications. However, the sensitivity of color change to strain is intrinsically limited, as the degree of deformation determines the wavelength shift. To overcome this limitation, auxetic photonic patterns that exhibit ultra-sensitive mechanochromism are designed. These patterns have a regular arrangement of cuts that expand to accommodate the strain, while the skeletal framework undergoes torsional deformation. Elastic photonic crystals composed of a non-close-packed array of colloidal particles are embedded in the cut area of the auxetic patterns. As the cut area amplifies the strains, the elastic photonic crystals show significant color change even for small total strains. The degree of local-strain amplification, or sensitivity of color change, is controllable by adjusting the width of cuts in the auxetic framework. In this work, a maximum sensitivity of up to 60 nm/% is achieved, which is 20 times higher than bulk films. It is believed that the auxetic photonic patterns with ultra-sensitive mechanochromism will provide new opportunities for the pragmatic use of mechanochromic materials in various fields, including structural health monitoring.

Association of Metabolic Syndrome with the Number of Breastfed Children in Postmenopausal Korean Women.

BACKGROUND: Metabolic syndrome is closely related to cardiovascular disease, and the prevalence of metabolic syndrome in postmenopausal women is increasing rapidly. OBJECTIVE: The purpose of this study is to investigate the association between the number of breastfed children and the risk factors for metabolic syndrome in postmenopausal women and to evaluate the association between metabolic syndrome and bone mineral density and body composition variables in postmenopausal women depending on the number of breastfed children Methods: Data from KNHANES V-1 and 2 (2010-2011) were used, and a total of 939 postmenopausal women with 1 to 6 breastfed children aged 65-80 years participated in this study. We divided these women into three groups (group1 with 1-2, group2 with 3-4, group3 with 5-6) depending on the number of breastfed children Results: In the analysis of the associations between metabolic syndrome and its risk factors, highdensity lipoprotein cholesterol was the most negatively strongly associated with group1 (OR=0.103 [0.047-0.225]), triglyceride showed the highest association with group2 (OR=7.760 [3.770-15.97]) and group3 (OR=7.668 [4.102-14.33]). The risk factors of metabolic syndrome except for highdensity lipoprotein cholesterol and triglyceride was not associated with group1. In contrast, all risk factors of metabolic syndrome displayed a high association with group2 and group3. CONCLUSION: The findings of the present study suggest that the number of breastfed children is significantly associated with a more significant number of risk factors of metabolic syndrome in postmenopausal women, and the association between metabolic syndrome and body composition variables may differ depending on the number of breastfed children.