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  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 19 (1980), S. 885-898 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Potentiometric titration curves of oxidized and reduced horse heart cytochrome c in 0.15M KCl at 20°C have been obtained by timed titration (0.125-0.500 μmol/sec) from the isoionic points (pH 10.2-10.4) to pH 3 and back to the isoionic point. Computer-assisted (PROPHET) data acquisition and blank corrections give curves with good precision with a maximum standard deviation of 0.3 groups for an average error of 1%. The potentiometric titration curve of reduced cytochrome c is reversible within the precision of the method and for the pH range studied. The potentiometric curves for oxidized cytochrome c titrated upscale (pH 3-10) and downscale (pH 10-3) are not reversible. However, they show the same ionization behavior after the initial downscale titration. This is probably the result of a conformational change. Comparison of the data herein reported with the titration curves of oxidized cytochrome c already published by others indicates good agreement on the basis of a normalization of the concentration of protein or on the basis of 25 titrable groups between the acid end point and the isoionic pH.Titration of the 2 μmol imidazole in the upscale or downscale direction gives the correct analytical concentration and pK′ after correction for the solvent titration. Titration of reduced cytochrome c in the presence and absence of an additional equivalent of imidazole gave a difference titration curve, which indicates that a group on the protein shifts from pK′ 5.8 to pK′ 5.3 in the presence of imidazole. The pK′ of imidazole, in the presence of the protein, remains at a nearly normal value of 7.34.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2020-02-12
    Description: The 2016 LoNNe (Loss of the Night Network) intercomparison campaign is the fourth of four campaigns planned during EU COST Action ES1204. The first campaign took place in 2013 in Lastovo, Croatia, the second in Madrid, Spain (Bará et al 2015), the third in Torniella and Florence, Italy (Kyba et al 2015a). The 2016 campaign took place at the Parc Astronòmic Montsec (PAM). The campaign was supported by the European Collective Awareness Platform for Social and Sustainable Innovation (CAPPSI) STARS4ALL, in which the activity is planned to become a continuous light pollution initiative (LPI). The financing of this campaign, which is listed as a milestone in the MoU of the COST Action ES1204, was unexpectedly waived by the EU-COST Office due to administrative complications and re-organization of the grant-periods. The campaign continued the strategy of taking measurements at multiple sites, this year with a main fixed site and then excursions to other sites. The goals of the campaigns included: ● Understanding the difference between extinction measurements made by DSLR photometry and classical astronomical (telescope) photometry, and also understanding the relation between extinction and sky brightness at these two sites. ● Examining the difference in radiance measured with the mosaic technique of the US National Parks Service camera compared to all-sky fisheye imagery ● Examining the relationships between all-sky and zenith radiance reported by different instruments ● Quantifying the sky brightness at the sites, including full zenith spectral radiance at selected locations ● Measuring the systematic uncertainty on handheld SQM observations due to unit-to-unit differences This report provides a brief synopsis of the campaign and its preliminary outcomes. Section 2 describes the measurement locations, the detailed activities of the participants, the instruments used, and the environmental conditions. Section 3 describes a meeting with local authorities that took place during the campaign. Section 4 provides some preliminary results, outlines the ongoing analyses, and presents research questions for the next campaign to address. Section 5 provides recommendations for future intercomparison campaigns. The Municipality of Balaguer coordinated with us regarding the time that architectural lamps were turned off, and the village of Àger allowed us to turn all street lighting off at a time of our choice.
    Language: English
    Type: info:eu-repo/semantics/report
    Format: application/pdf
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