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  • 1
    Electronic Resource
    Electronic Resource
    Cation selective tubular carrier-PVC-membranes containing polymeric plasticizer with low tendency of migration for Solid State Contact Electrodes (1994)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 336 (1994), S. 575-580 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The lifetime of cation selective carrier-PVC-membranes partially depends on the components' remaining in the membrane. An exchange of monomeric by polymeric plasticizers with low tendency to migrate lengthens the function time drastically. Other than for Na+ - and NH4+-selective membranes, it is essential for K+ - and Ca2+-selective membranes and optional for H+-selective membranes to incorporate lipophilic anions in order to make the phase transfer catalysis more efficient. The resistence to saponification of phthalic acid polyester gives H+-selective membranes a high stability of measured values even in the alkaline range.For anion selective PVC-membranes, instead of cation selective plasticizers the plasticizing qualities of a liquid charged ligand should be used.The tubular carrier-PVC-membranes of our ion selective flow through measuring systems are diffusion welded to the ends of two PVC-tubes [1] so that they are absolutely tight with no risk of potential leakage. Migration of the membrane components plasticizer and ionophore across this border as well as their extraction [2, 3] into the measuring solution [4] will naturally reduce the membrane's functionning time [5].
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19943360703
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  • 2
    Electronic Resource
    Electronic Resource
    Substituierte Alkinyle als axiale Liganden an häminähnlich gebundenem Eisen(III) - Einordnung in eine spektrochemische SerieHerrn Professor Dr. E. Hoyer zum 60. Geburtstag gewidmet (1991)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 333 (1991), S. 423-430 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Substituted Alkinyles as Axial Ligands at Hemine Like Bound Iron(III) - Incorporation into a Spectrochemical Series.Substituted lithium alkynyles Li—C≡C—R (R = tBu, Ph, p-Cl—C6H4, Me3Si, iPr3Si, Ph3Si) react with the hemine like macrocyclic iron(III) complex 6,13-di(ethoxycarbonyl)-5, 14-dimethyl-1, 4, 8, 11-tetraazatetradeca-4,6,12,14-tetraenato[2-]iron(III)-iodide (formula 2;) in tetrahydrofuran to form anionic low-spin di-adducts [fe(C≡C—R)2]-. The incorporation of the alkynyles into a spectrochemical series of the axial ligands (studied by the sharp equatorial-ligand-to-metal CT absorption band) results in the wavelength-sequence (nm): OH- (≍ 510) « N3- (≍ 625) 〈 tBu—C≡C- (664) 〈 NH3 (666) 〈 Ph—C≡C- (692) 〈 Ph—NH2 (695) 〈 Me3Si—C≡C- (698) 〈 SCN- (713) 〈 Ph3Si—C ≡ C- (716) 〈 CN- (739) 〈 4-picoline (759) 〈 pyridine (765) 〈 nicotinamide (776) 〈 methylnicotinat (788) 〈 pyrazine (798) and points to a significant π-acceptor ability of the silyl substituents.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19913330307
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  • 3
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    Studies of specific hepatic enzymes involved in the conversion of carbohydrates to lipids in rats exposed to prolonged spaceflight aboard Cosmos 1129 (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: (Previously announced in STAR as N81-32831)
    Keywords: LIFE SCIENCES (GENERAL)
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  • 4
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    Stabilization of the yeast desaturase system by low levels of oxygen (1983)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The stability of particulate palmitoyl-CoA desaturase preparations from anaerobically grown yeast cells was increased by exposure to low levels of oxygen. The stabilizing effect of oxygen may be based upon the increased amounts of palmitoleic acid and ergosterol that become available to the cells. These results suggest the evolutinary appearance of this system at a time when atmospheric oxygen was at a low level.
    Keywords: LIFE SCIENCES (GENERAL)
    Type: Origins of Life (ISSN 0302-1688); 13; March 19
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  • 5
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    Factors affecting the palmitoyl-coenzyme A desaturase of Saccharomyces cerevisiae (1975)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: The activity and stability of the palmitoyl-coenzyme A (CoA) desaturase complex of Saccharomyces cerevisiae was influenced by several factors. Cells, grown nonaerobically and then incubated with glucose, either in air or under N2, showed a marked increase in desaturase activity. Cycloheximide, added during such incubations, prevented the increase in activity, suggesting de novo synthesis. The stability of the desaturase from cells grown nonaerobically was affected by subsequent treatment of the cells; enzyme from freshly harvested cells, or from cells that were then shaken under nitrogen, readily lost activity upon washing or during density gradient analysis, whereas aerated cells, in the presence or absence of glucose, yielded stable enzyme preparations. The loss of activity in nonaerobic preparations could be reversed by adding soluble supernatant from these homogenates and could be prevented by growing the cells in the presence of palmitoleic acid and ergosterol, but not with several other lipids tested.
    Keywords: LIFE SCIENCES (GENERAL)
    Type: Journal of Bacteriology; 124; Nov. 197
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  • 6
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    Oxygen as a factor in eukaryote evolution - Some effects of low levels of oxygen on Saccharomyces cerevisiae (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A comparative study of the effects of varying levels of oxygen on some of the metabolic functions of the primitive eukaryote, Saccharomyces cerevisiae, has shown that these cells are responsive to very low levels of oxygen: the level of palmitoyl-Co A desaturase was greatly enhanced by only 0.03 vol % oxygen. Similarly, an acetyl-CoA synthetase associated predominantly with anaerobic growth was stimulated by as little as 0.1% oxygen, while an isoenzyme correlated with aerobic growth was maximally active at much higher oxygen levels (greater than 1%). Closely following this latter pattern were three mitochondrial enzymes that attained maximal activity only under atmospheric levels of oxygen.
    Keywords: LIFE SCIENCES (GENERAL)
    Type: Origins of Life; 9; Sept
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  • 7
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    Subunit specificity of the two acetyl-CoA synthetases of yeast as revealed by an immunological approach (1980)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Keywords: LIFE SCIENCES (GENERAL)
    Type: Biochimica et Biophysica Acta; 614; 1980
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  • 8
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    Experiment K304: Studies of specific hepatic enzymes and liver constituents involved in the conversion of carbohydrates to lipids in rats exposed to prolonged space flight (1981)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The effects of space flight on the activities of 26 enzymes concerned with carbohydrate and lipid metabolism in hepatic tissue taken from male Wistar rats are investigated. These activities were measured in the various hepatic cell compartments, i.e., cytosol, mitochondria and microsomes. In addition, the levels of glycogen, total lipids, phospholipids, triglycerides, cholesterol, cholesterol esters, and the fatty acid composition of the rat livers were also examined and quantified. A similar group of ground-based rats treated in an identical manner served as controls. Both flight and synchronous control rats were sacrificed at three time intervals: R+0, 7-11 hours after recovery; R+6, after 6 days; R+6(S), after 6 days (having undergone 2-5 hour periods of fixed stress in a "backupward" position on days 0, 3, 4, 5 and 6) and R+29, after 29 days post-flight. Although most of the enzyme activities and the amounts of liver constituents studied were unaffected by the period of weightlessness, some significant differences were observed.
    Keywords: LIFE SCIENCES (GENERAL)
    Type: US Rat Expts. Flown on the Soviet Satellite Cosmos 1129; p 35-100
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  • 9
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    Effects of aeration on formation and localization of the acetyl coenzyme A synthetases of Saccharomyces cerevisiae (1979)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Previous studies on the yeast Saccharomyces cerevisiae have shown that two different forms of the enzyme acetyl coenzyme A synthetase (ACS) are present, depending on the conditions under which the cells are grown. The paper evaluates the usefulness of a method designed to assay both synthetases simultaneously in yeast homogenates. The data presented confirm the possibility of simultaneous detection and estimation of the amount of both ACSs of S. cerevisiae in crude homogenates of this strain, making possible the study of physiological factors involved in the formation of these isoenzymes. One important factor for specifying which of the two enzymes is found in these yeast cells is the presence or absence of oxygen in their environment. Aeration not only affects the ratio of the two ACSs but also appears to affect the cellular distribution of these enzymes. Most of the data presented suggest the possibility that the nonaerobic ACS may serve as a precursor to the aerobic form.
    Keywords: LIFE SCIENCES (GENERAL)
    Type: Journal of Bacteriology; 137; Jan. 197
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  • 10
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    Oxygen requirements for formation and activity of the squalene expoxidase in Saccharomyces cerevisiae (1983)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: The effect of oxygen on squalene epoxidase activity in Saccharomyces cerevisiae was investigated. In cells grown in standing cultures, the epoxidase was localized mainly in the 'mitochondrial' fraction. Upon aeration, enzyme activity increased and the newly formed enzyme was associated with the 'microsomal' fraction. At 0.03 percent (vol/vol) oxygen, epoxidase levels doubled, whereas the ergosterol level was only slightly increased. Cycloheximide inhibited the increase in epoxidase under these conditions. An apparent K sub m for oxygen of 0.38 percent (vol/vol) was determined from a crude particulate preparation for the epoxidase.
    Keywords: LIFE SCIENCES (GENERAL)
    Type: Journal of Bacteriology (ISSN 0021-9193); 488-492
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