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  • Thermodynamics  (3)
  • Protoplasts  (2)
  • Tricalcium phosphate  (2)
  • cuticular lipid  (2)
  • Springer  (7)
  • Nature Publishing Group
  • Oxford University Press
  • Springer Nature
  • 1975-1979  (7)
  • 1960-1964
  • 1950-1954
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  • Springer  (7)
  • Nature Publishing Group
  • Oxford University Press
  • Springer Nature
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  • 1
    Digitale Medien
    Digitale Medien
    A thermodynamic analysis of the secondary transition in the spontaneous precipitation of calcium phosphate (1978)
    Springer
    Calcified tissue international 25 (1978), S. 209-216 
    Details
    ISSN: 1432-0827
    Schlagwort(e): Thermodynamics ; Kinetics ; Apatite ; Octacalcium phosphate ; Tricalcium phosphate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary A thermodynamic analysis has been made of the secondary transition stage in the spontaneous precipitation of calcium phosphate following the amorphous-crystalline transformation. The first formed crystalline material has a solubility similar to that of octacalcium phosphate (OCP) and the computed thermodynamic solubility product remains invariant in the pH range 7.00–8.60. The duration of the secondary stage is sensitive to pH and the transition appears to occur by hydrolysis of the first formed OCP-like phase to a more basic apatitic phase with a tricalcium phosphate (TCP) stoichiometry. The crystalline material at the end of this transition has an invariant solubility product, in the pH range 7.00 to 8.60, when the TCP-like molecular formula is assumed. Changes in the solution chemistry which accompany the solid-tosolid transitions are consistent with the above conclusions. The results of this study are also consistent with those of a previous study which suggest that the stability of the amorphous calcium phosphate phase is dependent upon the instability of the solution phase with respect to OCP formation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02010771
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    A thermodynamic analysis of the amorphous to crystalline calcium phosphate transformation (1978)
    Springer
    Calcified tissue international 25 (1978), S. 59-68 
    Details
    ISSN: 1432-0827
    Schlagwort(e): Amorphous calcium phosphate ; Thermodynamics ; Apatite ; Octacalcium phosphate ; Tricalcium phosphate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary A thermodynamic analysis of the precipitation of amorphous calcium phosphate (ACP) and its transformation to crystalline apatite has been made. A nearly constant ion product, over a wide variety of conditions, was obtained for a tricalcium phosphate (TCP)-like phase suggesting that the molecular unit which governs the solubility of ACP may be similar in composition to TCP. The introduction of 10% acid phosphate into the formula for the TCP ion product improves the fit of experimental data and results in an invariant ion product. The stability of ACP in solution was found to be dependent upon its thermodynamic instability with respect to an octacalcium phosphate (OCP)-like phase. The dependence of the induction period for the amorphous to crystalline transformation upon the pH and the Ca/P ratio of the solution is best explained by the assumption that an OCP-like phase is initially nucleated on the surfaces of the ACP particles. The events that occur in the immediate post-transition period suggest the hydrolysis of this OCP-like material to an apatitic phase.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02010752
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  • 3
    Digitale Medien
    Digitale Medien
    Hydroxyl content of solution-precipitated calcium phosphates (1979)
    Springer
    Calcified tissue international 27 (1979), S. 153-160 
    Details
    ISSN: 1432-0827
    Schlagwort(e): Hydroxide ; Hydroxyapatite ; Titration ; Precipitation ; Thermodynamics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Notizen: Summary A method is described for determination of the titratable hydroxide ion in calcium phosphate precipitates. The procedure requires accurate analysis of the other titratable species in the crystal lattice but is unaffected by the presence of other lattice constituents or impurities. The method was applied to precipitates that had been previously analyzed by solution thermodynamic techniques, and the results were consistent with the earlier observations. The hydroxide content of the precipitates increased with crystal maturity and with increasing pH of the precipitation medium. The hydroxide content of the amorphous phase and the immediate post-amorphous-crystalline transformation phase was shown to be nearly zero. After 3 to 4 days' maturation, the hydroxide content of precipitates prepared at pH values of 7, 8, and 9 was shown to increase to approximately 23, 40, 56% of that required for pure hydroxyapatite.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02441178
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  • 4
    Digitale Medien
    Digitale Medien
    Cytology of budding and cleavage in tobacco mesophyll protoplasts cultivated in saline medium (1978)
    Springer
    Planta 142 (1978), S. 11-21 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Budding ; Cleavage ; Mesophyll ; Protoplasts ; Tobacco
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Tobacco (Nicotiana tabacum L., cv. Maryland) mesophyll protoplasts cultivated in saline medium divide by bud formation, migration of one nucleus into the bud, and subsequent furrowing. This process was investigated light and electron microscopically. The cytoplasm of the growing bud is richer in dictyosomes, rough endoplasmic reticulum profiles, mitochondria, and small vacuoles than is the cytoplasm of the mother cell, but in early stages lacks plastids. Only patches of wall material are found; most of the cell surface appears naked. Oriented sections of the cleavage furrow do not reveal a contractile ring of microfilaments under the fixation conditions used. The furrow is flanked by numerous microtubules, and is rich in coated vesicles. Nuclear division appears normal, but the phragmoplast vesicles appear empty, and the phragmoplast seems to disintegrate again later. The nucleus migrating into the bud does not show any signs of associated contractile structures. The results demonstrate that, in principle, higher plant cells are capable of a mode of division usually said to be “yeast-like”. The events of karyokinesis and cell plate formation are not therefore obligatorily linked processes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00385114
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  • 5
    Digitale Medien
    Digitale Medien
    Time course of hormonal control of the first mitosis in tobacco mesophyll protoplasts cultivated in vitro (1979)
    Springer
    Planta 147 (1979), S. 181-185 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Mitosis ; Nicotiana ; Phytohormones ; Protoplasts
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The presence of auxin and cytokinin is necessary for the induction of mitosis in tobacco mesophyll protoplasts cultivated in vitro. In their absence, protoplasts firstly accumulate inhibitors of mitosis in the culture medium, possibly because of non-coordinated cell-wall synthesis, and secondly evolve a nonmitotic and degenerative metabolism. By changing the intoxified medium, it is possible to show that auxin is necessary from the beginning of culture, while cytokinin is only required later to allow a step in the development of the mitotic apparatus.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00388735
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Mating stimulant pheromone and cuticular lipid constituents ofFannia femoralis (Stein) (Diptera: Muscidae) (1978)
    Springer
    Journal of chemical ecology 4 (1978), S. 83-93 
    Details
    ISSN: 1573-1561
    Schlagwort(e): Fannia femoralis (Stein) ; pheromone ; mating stimulant pheromone ; (Z)-11-hentriacontene ; cuticular lipid ; fly
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract The cuticular lipids of male and femaleFannia femoralis were similar for recently emerged insects but soon began to develop chromatographic patterns characteristic of each sex. Mature females contained more C31 and C33 monoolefin in the cuticular lipid than males. Also, the double bonds in the monoolefins of the female lipid were situated predominantly at the eleventh and thirteenth carbons, while most of those from the males were centrally located in the molecule or at the ninth carbon. The female C31 monoolefin stimulated copulation by the males, but more mating activity occurred when the saturated hydrocarbons present in the female cuticular lipids were added. The synthetic monoolefin most active as a mating stimulant pheromone was (Z)-11-hentriacontene, but the addition of female alkanes or of syntheticn-alkanes to (Z)-11-hentriacontene increased the activity of the synthetic pheromone.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00988263
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  • 7
    Digitale Medien
    Digitale Medien
    Mating stimulant pheromone and cuticular lipid constituents ofFannia pusio (Wiedemann) (Diptera: Muscidae) (1978)
    Springer
    Journal of chemical ecology 4 (1978), S. 73-81 
    Details
    ISSN: 1573-1561
    Schlagwort(e): Fannia pusio (Wiedemann) ; pheromone ; mating stimulant pheromone ; (Z)-11-hentriacontene ; cuticular lipid ; fly
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Chromatograms of the cuticular lipids washed from newly emerged male and femaleFannia pusio were nearly identical. By the time the flies were 1 day old, the chromatographic profiles for the sexes were different. Mature females contained more C31- and C33-hydrocarbons than the males. The double bonds of the female monoolefins were mostly at the eleventh and thirteenth carbons, but those of the males were predominantly at the ninth carbon. Most active in stimulating copulation by males were the unbranched monoolefins with 31 and 33 carbons from the females. When they were synthesized and tested, the most active compound was (Z)-11-hentriacontene.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00988262
    Standort Signatur Erwartet Verfügbarkeit
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