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In this study, a microfluidic process is proposed for preparing monodisperse micrometer-sized hydrogel beads. This process utilizes non-equilibrium aqueous droplets formed in a polar organic solvent. The water-in-oil droplets of the hydrogel precursor rapidly shrunk owing to the dissolution of water molecules into the continuous phase. The shrunken and condensed droplets were then gelled, resulting in the formation of hydrogel microbeads with sizes significantly smaller than the initial droplet size. This study employed methyl acetate as the polar organic solvent, which can dissolve water at 8%. Two types of monodisperse hydrogel beads—Ca-alginate and chitosan—with sizes of 6–10 μm (coefficient of variation < 6%) were successfully produced. In addition, we obtained hydrogel beads with non-spherical morphologies by controlling the degree of droplet shrinkage at the time of gelation and by adjusting the concentration of the gelation agent. Furthermore, the encapsulation and concentration of DNA molecules within the hydrogel beads were demonstrated. The process presented in this study has great potential to produce small and highly concentrated hydrogel beads that are difficult to obtain by using conventional microfluidic processes. 相似文献
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Lifelong learning is essential to participation in society, and presents important challenges for educational gerontology. This study compares Canadian and Japanese perspectives on (a) attitudes toward aging, (b) the learning needs of older adults, and (c) the role of centers of learning. Surveys were conducted of sample populations in two elder colleges in Japan (N = 419, 753; mean age 66.4,70.5) and two senior centers in Canada (N = 122; mean age 75.0). Results suggest Canadian respondents have more positive attitudes toward aging; Japanese respondents have greater needs for social/communicative learning; and Canadians have a greater need for traditional learning. Future implications for older-adult education and research are discussed. 相似文献
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This study compares older adult learning in Korean and Japanese sample populations, paying special attention to learning after age 70. Surveys with nearly identical questionnaires were conducted in the Bundang Senior Welfare Center in Korea (N = 549, mean age 73.6 years) and at Osaka Prefecture Senior College in Japan (N = 1,491, 787, mean age = 67.4, 69.5 years). The main results are as follows: (a) in terms of learning needs, selected ratios of topics of “life review” and “communication with other seniors” increased as respondents increased in age from their 60s to 70s in both countries; (b) attitudes toward learning and social activities changed from “Novelty” to “Continuity” to “Disengagement” as respondents increased in age in both countries; and (c) the threshold age to old age was identified at around 75 years, not 70 years, particularly in Korean data. These results suggest that old age is a diverse period, and that creating ways to facilitate learning after age 70 is an urgent issue in the field of educational gerontology. 相似文献
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Hori Ghaneialvar Leila Soltani Hamid Reza Rahmani Abbas Sahebghadam Lotfi Masoud Soleimani 《Indian journal of clinical biochemistry : IJCB》2018,33(1):46-52
Mesenchymal stem cells are multipotent cells capable of replicating as undifferentiated cells, and have the potential of differentiating into mesenchymal tissue lineages such as osteocytes, adipocytes and chondrocytes. Such lineages can then be used in cell therapy. The aim of present study was to characterize bone marrow derived mesenchymal stem cells in four different species, including: sheep, goat, human and mouse. Human bone-marrow mesenchymal stem cells were purchased, those of sheep and goat were isolated from fetal bone marrow, and those of mouse were collected by washing bone cavity of femur and tibia with DMEM/F12. Using flow-cytometry, they were characterized by CD surface antigens. Furthermore, cells of third passage were examined for their osteogenic and adipogenic differentiation potential by oil red and alizarin red staining respectively. According to the results, CD markers studied in the four groups of mesenchymal stem cells showed a different expression. Goat and sheep expressed CD44 and CD166, and weakly expressed CD34, CD45, CD105 and CD90. Similarly, human and mouse mesenchymal cells expressed CD44, CD166, CD105 and CD90 whereas the expression of CD34 and CD45 was negative. In conclusion, although all mesenchymal stem cells display plastic adherence and tri-lineage differentiation, not all express the same panel of surface antigens described for human mesenchymal stem cells. Additional panel of CD markers are necessary to characterize regenerative potential and possible application of these stem cells in regenerative medicine and implantology. 相似文献
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