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'Fluorescence Lifetimes' in keywords Facet   Publication Year 1982  [X]
Facet   section ZfN Section C  [X]
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1Author    SeymourSteven BrodyRequires cookie*
 Title    Absorption and Picosecond Fluorescence Characteristics o f Chlorophyll Vesicles as a Function o f Temperature  
 Abstract    With chlorophyll a-dipalmitoylphosphatidylcholine-liposomes, the absorption increases at 706 and 450 nm, and decreases at 660 and 420 nm, as the temperature is lowered. As the temperature is increased opposite changes are observed. A lipid phase change occurs at 34°. The pigment to lipid ratio is 1 to 5 in the liposome. With chlorophyll a-soy bean lecithin-liposomes the absorption increases at 706, 680 and 440 nm, and decreases at 650 and 430 nm, as the temperature is lowered. As the temperature is increased, opposite changes are observed. A lipid phase change occurs at 26-27 °C. The pigment to lipid ratio is 1 to 13. The spectral change at 706 nm is identified with aggregated chlorophyll. The concentration o f chlorophyll aggregate increases as the temperature is lowered, and decreases as the temperature is raised. Fluorescence decay from chlorophyll a-soy bean lecithin-liposomes is biphasic. The lifetimes o f freshly prepared liposomes are 121 ± 4 ps and 1400 + 200 ps. The relative contribution o f the fast and slow fluorescence components are modified by temperature. Heating results in an increase in both lifetimes, and an increase in fluorescence from the long lived component. These changes are interpreted as resulting from a decrease in energy transfer and concentration quenching. The origin o f the biphasic fluorescence and spectral transformations in liposomes, and the possible re­ lation between in vitro and in vivo picosecond fluorescence is discussed. 
  Reference    Z. Naturforsch. 37c, 260—267 (1982); received October 161981 
  Published    1982 
  Keywords    Liposome, Chlorophyll, Photosynthesis, Fluorescence Lifetime, Lipid Phase Change 
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 TEI-XML for    default:Reihe_C/37/ZNC-1982-37c-0260.pdf 
 Identifier    ZNC-1982-37c-0260 
 Volume    37 
2Author    S. S. BrodyRequires cookie*
 Title    Effect of Aging on the Fluorescence Lifetime of Chloroplasts  
 Abstract    The lifetime of fluorescence from pea chloroplasts at room temperature increases with age. The ratio of the fluorescence intensities of the slow to fast decay components, decreases with age o f the chloroplasts. This observation can account for the wide range o f lifetimes reported in the literature. The variability of biological material (cultured and prepared with similar procedures) introduces considerable variation in the fluorescence lifetimes measured with pea chloroplasts. Sonication of chloroplasts results in an increase in both the fast and slow fluorescence lifetimes. 
  Reference    Z. Naturforsch. 37c, 881—883 (1982); received January 4/May 24 1982 
  Published    1982 
  Keywords    Photosynthesis, Fluorescence Lifetimes, Aging, Sonicated Chloroplasts 
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 TEI-XML for    default:Reihe_C/37/ZNC-1982-37c-0881.pdf 
 Identifier    ZNC-1982-37c-0881 
 Volume    37