Properties of the Broad-Range Nematic Phase of a Laterally Linked H-Shaped Liquid Crystal Dimer

In search for novel nematic materials, a laterally linked H-shaped liquid crystal dimer have been synthesized and characterized. The distinct feature of the material is a very broad temperature range (about 50 oC) of the nematic phase, which is in contrast with other reported H-dimers that show predominantly smectic phases. The material exhibits interesting textural features at the scale of nanometers (presence of smectic clusters) and at the macroscopic scales. Namely, at a certain temperature, the flat samples of the material show occurrence of domain walls. These domain walls are caused by the surface anchoring transition and separate regions with differently tilted director. Both above and below this transition temperature the material represents a uniaxial nematic, as confirmed by the studies of defects in flat samples and samples with colloidal inclusions, freely suspended drops, X-ray diffraction and transmission electron microscopy.Comment: 30 pages (including Supplementary Information), 7 Figure

Adolescent physical activity participation and motivational determinants across gender, age, and race.

Background: Physical activity (PA) declines as adolescents get older, and the motivational determinants of PA warrant further investigation. The purposes of this study were to investigate the amount of physical and sedentary activity that adolescents participated in across age, gender, and race, and to investigate adolescents’ attraction to PA and their perceived barriers and benefits across age, gender, and race. Methods: High school students (N = 1163) aged between 13 and 16 years completed questionnaires on minutes and intensity of physical and sedentary activity, interests in physical activity, and perceived benefits and barriers to participating in PA. Results: A series of multivariate analyses of variance were conducted and followed up with discriminant function analysis. PA participation decreased in older females. In addition, fun of physical exertion was a primary attraction to PA for males more than females. Body image as an expected outcome of participating in PA contributed most to gender differences. Conclusion: There is a need to determine why PA drops-off as females get older. Findings underscore the importance of structuring activities differently to sustain interest in male and female adolescents, and highlights motives of having a healthy body image, and making PA fun to enhance participation