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  • Polarography  (3)
  • *Light  (2)
  • Burkard sporetrap  (2)
  • 1995-1999  (7)
  • 1
    Digitale Medien
    Digitale Medien
    Sampling in aerobiology. Differences between traverses along the length of the slide in Hirst sporetraps (1996)
    Springer
    Aerobiologia 12 (1996), S. 161-166 
    Details
    ISSN: 1573-3025
    Schlagwort(e): Aerobiology ; Methodology ; Sampling error ; Burkard sporetrap
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Two years of data from four longitudinal traverses along each day's slide prepared from a continuously running Burkard sporetrap have been analyzed statistically. Using the Friedman test, a statistically significant difference was found between the four traverses, with a greater than 7% loss of pollen grains in the two outer traverses in relation to the inner. Four slides were then selected for more detailed analysis, using 18 longitudinal traverses with a 1-mm separation from the upper to the lower edge of the Melinex tape. There was found to be a progressive decline from the centre to the outside, and more than 4% of pollen grains were found outside the typical 14 mm width of the impaction orifice. There was no correlation between pollen grain size and the decline in counts from the centre to the outside. For the complete data set, there was a general rise in the diversity of bollen types with increasing sample counts, but above about 1000 pollen grains per sample there were no more than 27 pollen types found, often even fewer. A discussion is presented of whether four traverses really should be a fixing sample size, or whether it might be better to fix the total pollen count beginning with a traverse in the middle of the slide and ending with a variable number of traverses when that count is reached.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02447407
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Sampling in aerobiology. Differences between traverses along the length of the slide in Hirst sporetraps (1996)
    Springer
    Aerobiologia 12 (1996), S. 161-166 
    Details
    ISSN: 1573-3025
    Schlagwort(e): Aerobiology ; Methodology ; Sampling error ; Burkard sporetrap
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Two years of data from four longitudinal traverses along each day's slide prepared from a continuously running Burkard sporetrap have been analyzed statistically. Using the Friedman test, a statistically significant difference was found between the four traverses, with a greater than 7% loss of pollen grains in the two outer traverses in relation to the inner. Four slides were then selected for more detailed analysis, using 18 longitudinal traverses with a 1-mm separation from the upper to the lower edge of the Melinex tape. There was found to be a progressive decline from the centre to the outside, and more than 4% of pollen grains were found outside the typical 14 mm width of the impaction orifice. There was no correlation between pollen grain size and the decline in counts from the centre to the outside. For the complete data set, there was a general rise in the diversity of pollen types with increasing sample counts, but above about 1000 pollen grains per sample there were no more than 27 pollen types found, often even fewer. A discussion is presented of whether four traverses really should be a fixing sample size, or whether it might be better to fix the total pollen count beginning with a traverse in the middle of the slide and ending with a variable number of traverses when that count is reached.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02248144
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Electrochemical behavior of metallothioneins and related molecules. Part I: Lys-Cys-Thr-Cys-Cys-Ala thionein fragment [56-61] MT I (1995)
    Weinheim : Wiley-Blackwell
    Electroanalysis 7 (1995), S. 663-669 
    Details
    ISSN: 1040-0397
    Schlagwort(e): Polarography ; Methallothioneins ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In order to obtain a better understanding of the electrochemical behavior of the Metallothionein (MT), the peptidic fragment Lys-Cys-Thr-Cys-Cys-Ala [56-61] MT I (FT) compound constitutive of the proteic structure has been studied. The elucidation of the electrochemical mechanism at the electrode could be reached from comparison with other mechanisms proposed for similar molecules. This study stems from a more complete work. Under our experimental conditions, with a low concentration of the substance (〈 5 × 10-5 M) and the use of a dropping mercury electrode, a diffusion controlled mechanism is suggested for the electrochemical behavior of FT. In this case the mercury electrode itself is involved in the charge transfer step and the polarographic response is attributed to the oxidation of the mercury electrode in the presence of the chelating agent FT. This hypothesis was supported by the lack of modification of the electrocapillary curves in the presence of low concentration of FT in relation to those obtained with the supporting electrolyte alone and by the linear relationship between the polarographic intensity and the concentration at a low concentration of FT. The influence of the pH of the solution on the behavior of FT was investigated using DC and DPP methods. The variation of i1, ip and Ep with pH was determined. From these results the apparent acid-base dissociation constant of the FT was evaluated, corresponding to the dissociation of protons from the thiol groups. Likewise the apparent stability constants of the Hg-FT were estimated as a function of the pH. It was assumed that the main complex of Hg-FT possessed a stoichiometry of 1 : 1 but it is probable that two or more different complexes coexisted.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/elan.1140070713
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  • 4
    Digitale Medien
    Digitale Medien
    Electrochemical behavior of metallothioneins and related molecules. Part III: Metallothionein (1995)
    Weinheim : Wiley-Blackwell
    Electroanalysis 7 (1995), S. 674-680 
    Details
    ISSN: 1040-0397
    Schlagwort(e): Polarography ; Metallothionein ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The electrochemical behavior of Cd-Zn Thionein from rabbit liver and horse kidney with respect to pH of the solution at the dropping mercury electrode was studied, using differential pulse polarography (DPP). At pH 7.5 three well defined peaks were observed at a potential different from the potentials corresponding to pure Cd2+ and Zn2+. Two different electrochemical systems are involved: the oxidation of the mercury electrode in the presence of thiol groups contained in the metallothionein and the reduction of either free (pH 〈 4) or complexed (pH 〉 6) metal ions. The apparent acid-base dissociation constant of metallothionein was estimated. The apparent stability constants of the complexes CdT, ZnT and HgT were estimated at different pH values. Cadmium forms at least two complexes with thionein exhibiting different stabilities and probably different structures. Modifications in the polarograms with the addition of Cd, Zn and the peptidic fragment [56-61] MT I, a molecule intrinsic to the metallothionein structure, were studied. A diagram showing the oxido-reduction potentials corresponding to twelve diflerent electrochemical species is given. DPP allows one to distinguish the chemical forms of compounds (speciation).
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/elan.1140070715
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  • 5
    Digitale Medien
    Digitale Medien
    Electrochemical behavior of metallothioneins and related molecules. Part II: Lys-Cys-Thr-Cys-Cys-Ala thionein fragment [56-61] MT I in the presence of cadmium and/or zinc (1995)
    Weinheim : Wiley-Blackwell
    Electroanalysis 7 (1995), S. 670-673 
    Details
    ISSN: 1040-0397
    Schlagwort(e): Polarography ; Metallothioneins ; related molecules ; Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: An electrochemical study, using differential pulse polarography (DPP), of a peptide Lys-Cys-Thr-Cys-Cys-Ala Thionein Fragment [56-61] MT I (FT) was performed in order to compare the behavior of metallothioneins and that of this less complex molecule, intrinsic to the metallothionein structure. The influence of different parameters, such as the solution pH and the concentration of metal elements, cadmium and zinc was investigated. Two different electrochemical systems were distinguished: in the first one, the mercury electrode itself is involved in the charge transfer steps; in this case, peaks are attributed to the oxidation of the mercury electrode in the presence of the peptide acting as a chelating agent. The second electrochemical system corresponds to the reduction of metal cations, cadmium and zinc, at a dropping mercury electrode either as free ions or complexed by the peptide. The apparent stability constants for complexes of FT with cadmium, zinc and mercury were estimated. The order of affinity is: K′HgFT ≫ K′CdFT 〉 K′ZnFT. The DPP response can be used for elucidation of the chemical forms of compounds (speciation).
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/elan.1140070714
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  • 6
    facet.materialart.
    Unbekannt
    Regulation of the mammalian pineal by non-rod, non-cone, ocular photoreceptors (1999)
    American Association for the Advancement of Science (AAAS)
    Details
    Publikationsdatum: 1999-04-16
    Beschreibung: In mammals, ocular photoreceptors mediate an acute inhibition of pineal melatonin by light. The effect of rod and cone loss on this response was assessed by combining the rd mutation with a transgenic ablation of cones (cl) to produce mice lacking both photoreceptor classes. Despite the loss of all known retinal photoreceptors, rd/rd cl mice showed normal suppression of pineal melatonin in response to monochromatic light of wavelength 509 nanometers. These data indicate that mammals have additional ocular photoreceptors that they use in the regulation of temporal physiology.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lucas, R J -- Freedman, M S -- Munoz, M -- Garcia-Fernandez, J M -- Foster, R G -- New York, N.Y. -- Science. 1999 Apr 16;284(5413):505-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, Sir Alexander Fleming Building, Imperial College of Science, Technology and Medicine, London, SW7 2AZ, UK. r.j.lucas@ic.ac.uk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10205062" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Biological Clocks/physiology ; Circadian Rhythm/*physiology ; Cryptochromes ; Darkness ; *Drosophila Proteins ; *Eye Proteins ; Flavoproteins/genetics/physiology ; *Light ; Light Signal Transduction ; Melatonin/*metabolism ; Mice ; Mice, Inbred C3H ; Mice, Transgenic ; *Photoreceptor Cells, Invertebrate ; Photoreceptor Cells, Vertebrate/*physiology ; Pineal Gland/*metabolism ; Receptors, G-Protein-Coupled ; Retina/cytology/*physiology ; Retinal Ganglion Cells/physiology ; Retinal Pigments/genetics/physiology
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Publiziert von American Association for the Advancement of Science (AAAS)
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  • 7
    facet.materialart.
    Unbekannt
    Regulation of mammalian circadian behavior by non-rod, non-cone, ocular photoreceptors (1999)
    American Association for the Advancement of Science (AAAS)
    Details
    Publikationsdatum: 1999-04-16
    Beschreibung: Circadian rhythms of mammals are entrained by light to follow the daily solar cycle (photoentrainment). To determine whether retinal rods and cones are required for this response, the effects of light on the regulation of circadian wheel-running behavior were examined in mice lacking these photoreceptors. Mice without cones (cl) or without both rods and cones (rdta/cl) showed unattenuated phase-shifting responses to light. Removal of the eyes abolishes this behavior. Thus, neither rods nor cones are required for photoentrainment, and the murine eye contains additional photoreceptors that regulate the circadian clock.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Freedman, M S -- Lucas, R J -- Soni, B -- von Schantz, M -- Munoz, M -- David-Gray, Z -- Foster, R -- New York, N.Y. -- Science. 1999 Apr 16;284(5413):502-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, Alexander Fleming Building, Imperial College of Science, Technology and Medicine, London, SW7 2AZ, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10205061" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Biological Clocks/*physiology ; Circadian Rhythm/*physiology ; *Light ; Mice ; Mice, Transgenic ; Motor Activity ; *Ocular Physiological Phenomena ; Photoreceptor Cells, Vertebrate/*physiology ; Pigments, Biological/physiology ; Retinal Cone Photoreceptor Cells/physiology ; Retinal Pigments/physiology ; Retinal Rod Photoreceptor Cells/physiology
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Publiziert von American Association for the Advancement of Science (AAAS)
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