RESUMEN
Single phase CeO2 nanocrystals were bio-synthesized using Hoodia gordonii natural extract as an effective chelating agent. The nanocrystals with an average diameter of ãØã ~ 5-26 nm with 4+ electronic valence of Ce displayed a remarkable UV selectivity and an exceptional photostability. The diffuse reflectivity profile of such CeO2 exhibited a unique UV selectivity, in a form of a Heaviside function-like type profile in the solar spectrum. While the UV reflectivity is significantly low; within the range of 0.7%, it reaches 63% in the VIS and NIR. Their relative Reactive Oxygen Species (ROS) production was found to be < 1 within a wide range of concentration (0.5-1000 µg/ml). This exceptional photostability conjugated to a sound UV selectivity opens a potential horizon to a novel family of green nano-cosmetics by green nano-processing.
Asunto(s)
Cerio , Nanopartículas , Antioxidantes/química , Cerio/química , Nanopartículas/química , Especies Reactivas de OxígenoRESUMEN
The authors examine the effects of demographic aging and the changing age structure on the labor force in the United States, Canada, and Japan over the period from 1950 to 1980. They find that "the changing age structure and population aging have generally had a favorable effect on the proportion of labour force or crude labour force rate.... The remarkable feature was the rate effect of the female labour force, which was positive and often substantially reinforced the positive age effect.... The proportion of the female labour force soared during the 1960s and 1970s in these countries, and a dramatic convergence of male and female labour force participation rates took place."
Asunto(s)
Empleo , Dinámica Poblacional , Factores Sexuales , Américas , Asia , Canadá , Demografía , Países Desarrollados , Economía , Asia Oriental , Fuerza Laboral en Salud , Japón , América del Norte , Población , Características de la Población , Investigación , Estados UnidosRESUMEN
PIP: During the past decade, the international statistical community has made several efforts to develop standards for the definition, collection and publication of statistics on international migration. This article surveys the history of official initiatives to standardize international migration statistics by reviewing the recommendations of the International Statistical Institute, International Labor Organization, and the UN, and reports a recently proposed agenda for moving toward comparability among national statistical systems. Heightening awareness of the benefits of exchange and creating motivation to implement international standards requires a 3-pronged effort from the international statistical community. 1st, it is essential to continue discussion about the significance of improvement, specifically standardization, of international migration statistics. The move from theory to practice in this area requires ongoing focus by migration statisticians so that conformity to international standards itself becomes a criterion by which national statistical practices are examined and assessed. 2nd, the countries should be provided with technical documentation to support and facilitate the implementation of the recommended statistical systems. Documentation should be developed with an understanding that conformity to international standards for migration and travel statistics must be achieved within existing national statistical programs. 3rd, the call for statistical research in this area requires more efforts by the community of migration statisticians, beginning with the mobilization of bilateral and multilateral resources to undertake the preceding list of activities.^ieng