Studying Electrophoretic Separations Using Cholate Micelles: Effects Of Ph, Temperature, And Composition

Micelle-forming bile salts have previously been shown to be effective pseudo-stationary phases for separating the chiral isomers of binaphthyl compounds with micellar electrokinetic capillary chromatography (MEKC). Here, cholate micelles are systematically investigated via electrophoretic separations and NMR using R, S-1, 1¿- binaphthyl- 2, 2¿-diylhydrogenphosphate (BNDHP) as a model chiral analyte. The pH, temperature, and concentration of BNDHP were systematically varied while monitoring the chiral resolution obtained with MEKC and the chemical shift of various protons in NMR. NMR data for each proton on BNDHP is monitored as a function of cholate concentration: as cholate monomers begin to aggregate and the analyte molecules begin to sample the micelle aggregate we observe changes in the cholate methyl and S-BNDHP proton chemical shifts. From such NMR data, the apparent CMC of cholate at pH 12 is found to be about 13-14 mM, but this value decreases at higher pH, suggesting that more extreme pHs may give rise to more effective separations. In general, CMCs increase with temperature indicating that one may be able to obtain better separations at lower temperatures. S-BNDHP concentrations ranging from 50 ¿M to 400 ¿M (pH 12.8) gave rise to apparent cholate CMC values from 10 mM to 8 mM, respectively, indicating that S-BNDHP, the chiral analyte molecule, may play an active role in stabilizing cholate aggregates. In all, these data show that NMR can be used to systematically investigate a complex multi-variable landscape of potential optimizations of chiral separations.

Studying the Roles of Nonprofits, Government, and Business in Providing Activities and Services to Youth in the Phoenix Metropolitan Area

The article addresses the questions, What do children in urban areas do on Saturdays? What types of organizational resources do they have access to? Does this vary by social class? Using diary data on children's activities on Saturdays in the Phoenix-Mesa-Scottsdale metropolitan area, the authors describe the different types of venues (households, businesses, public space, associations, charities, congregations, and government/tribal agencies) that served different types of children. They find that the likelihood of using a charity or business rather than a government or tribal provider increased with family income. Also, the likelihood of using a congregation or a government facility rather than a business, charity, or household increased with being Hispanic. The authors discuss the implications for the urban division of labor on Saturdays and offer research questions that need further investigation.

Where Is "Home"? Value Conflicts, Identity Crises and the Formation of Cosmopolitan Identity in Myanmar Students Studying in the United States

Fully engaging in a new culture means translating oneself into a different set of cultural values, and many of the values can be foreign to the individual. The individual may face conflicting tensions between the psychological need to be a part of the new society and feelings of guilt or betrayal towards the former society, culture or self. Many international students from Myanmar, most of whom have little international experience, undergo this value and cultural translation during their time in American colleges. It is commonly assumed that something will be lost in the process of translation and that the students become more Westernized or never fit into both Myanmar and US cultures. However, the study of the narratives of the Myanmar students studying in the US reveals a more complex reality. Because individuals have multifaceted identities and many cultures and subcultures are fluctuating and intertwined with one another, the students¿ cross-cultural interactions can also help them acquire new ways of seeing things. Through their struggle to engage in the US college culture, many students display the theory of ¿cosmopolitanism¿ in their transformative identity formation process and thus, define and identify themselves beyond one set of cultural norms.