3 resultados para isolating

em Digital Archives@Colby


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The history of a gay and lesbian student community at Colby seems to point to the difficulty of visibility. For students who were able to find others like themselves, their group of lesbian and gay friends had to remain underground. For students who were grappling with their newly found, socially stigmatized sexuality, the experience was isolating if they did not know where to find others like themselves. This paper seeks to address the social forces that kept sexually variant students from expressing their sexual identities openly on campus. Part of this difficulty is attributable to the compulsory heterosexuality assumed by general American society at the time, manifested in the silence or outright hostility directed against homosexuals. Naturally, Colby students replicated this assumption. Some of the students we interviewed seemed to internalize compulsory heterosexuality, while it was forced upon others. Religion and psychology were two methods of enforcing heterosexuality that were relevant to the people we interviewed. Another significant obstacle to visibility was Colby's location and the nature of Colby's student body. Waterville, unlike more urban cities, did not have a history of gay life, and thus an established gay community or gay identity into which one could be socialized. Colby, as a small, homogeneous and isolated space, posed difficulties in establishing a gay community as the population to draw from was small and regulated.

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To date there are no analytical techniques designed to exclusively measure bioavailable iron in marine environments. The goal of this research is to develop such a technique by isolating the bioavailable iron using the terrestrial siderophore desferrioxamine B (DFB). This project contained many challenging aspects, but the specific goal of this study was to develop a robust analytical technique for quantification of Fe(III)-DFB complexes at nanomolar concentrations. Past work showed that oxalate (Ox) promotes photodissociation of Fe(III)-DFB to Fe(Il), and we are specifically interested in the mechanism of this process. A model was developed using known thermodynamic constants for Fe(III)-DFB and Fe(III) oxalato complexes and adjusting for ionic strength. The model was confirmed by monitoring the UV-VIS absorbance of the system at a variety of oxalate concentrations and pH. The model did not include ternary complexes. Next., the rate of Fe(1I) production during UV irradiation was examined. The results showed that the rate of Fe(II) production was based entirely on the [Fe(Ox)?]3- speciation, and that reoxidation of Fe(II) occurred via reactive oxygen intermediates. This reoxidation could be avoided by either decreasing the oxygen concentration or by adding a Fe(II) stabilizing reagent, such as ferrozine. Further studies need to be done to confirm that these results apply at sub nanomolar concentrations, and the issue of Fe(II) reoxidation at lower Fe concentrations needs to be addressed.

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Volvox carteri, a multi-celled green algae, can grow synchronously given a sixteen hour light period followed by an eight hour dark period, a cycle which is repeated for a 48 hour growth cycle total. Near the end of each light period, reproductive cells divide rapidly resulting in the differentiation of ceIls. When the dark period begins, this differentiation stops and the cells remain dormant with little protein synthesis or differentiation occurring. Immediately after the lights come back on, however, the cells again undergo rapid protein synthesis and complete their differentiation. Previous studies have concluded that Volvox carteri discontinue protein synthesis during the dark phase due to regulation at the translational level and not the transcriptional level. Therefore, the inhibition of protein synthesis does not lie in the transfer of the protein coding sequence from DNA to mRNA, but rather in the transfer of this information from the mRNA to the ribosomes. My research examined this translational regulation to determine the factor(s) causing the discontinuation of protein synthesis during the dark phase. Evidence from other research further suggests that the control of translation lies in the initiation step rather than the elongation step. Eukaryotic initiation factors aid in the binding of the ribosomal subunits to the mRNA to initiate protein synthesis. It is known that initiation factors can be modified by phosphorylation, regulating their activity. Therefore, my study focused upon isolating some of these initiation factors in order to determine whether or not such modifications are responsible for the inhibition of dark phase protein synthesis in Volvox carteri.