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  • Analytical Chemistry and Spectroscopy  (5)
  • Information processing  (2)
  • 1
    ISSN: 1615-6102
    Keywords: Physarum polycephalum ; Spatio-temporal pattern of Ca2+ ; concentration ; Information processing ; Intracellular Ca2+ ; Chemotaxis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The development of a spatio-temporal pattern of Ca2+ concentration by a plasmodium ofPhysarum polycephalum during chemotaxis was studied using fura-2. Whenever the cell displayed coordinated migration in one direction as a whole body, a spatiotemporal pattern was established with a characteristic feature along the longitudinal axis. Calcium concentration oscillated with a period of a few minutes within the cell; the mean concentration at the front was higher than that at the rear. When the cell was given an attractant only at the rear end, the mean concentration rose at the site of application with an immediate increase in the frequency of oscillation. First, the change of the frequency is propagated toward the other end and then the mean level of the Ca2+ concentration at the non-stimulated site decreases. As a result, the Ca2+ gradient is reversed along the cell, which then begins to migrate in a coordinated manner in the reverse direction. This study showed that the spatiotemporal pattern of Ca2+ concentration is closely related to information processing for coordinated migration in chemotaxis. The role of the pattern in that process is discussed.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1615-6102
    Keywords: Chemotaxis ; Information processing ; Oscillation ; Physarum polycephalum ; Thermal image camera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The spatial and temporal pattern of oscillating temperatures on the cell surface of a plasmodial strand ofPhysarum polycephalum was measured with a sensitive thermal image camera. The longitudinal tension of the strand was studied simultaneously. In the absence of chemical stimulation, the phases of the temperature oscillation observed at various portions of the strand were entrained with almost coincidental phase. The temperature and tension oscillation were synchronized, although the phase difference between them was occasionally changed. With local chemical stimulation, the phase of the temperature oscillation advanced in the portion to which the plasmodium would be induced to migrate. The phases between temperature and tension oscillations then became constant. The mechanism by which the plasmodium processes local information of chemical stimulus to global information for the migration is discussed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 26 (1995), S. 963-967 
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: High-pressure Raman spectra of liquid and solid CH4 and CD4 were measured up to 18 and 13 GPa, respectively, at 300 K in a gasketed diamond-anvil cell. On the basis of visual observations under the polarizing microscope and changes in the Raman spectra, it was confirmed that there are only two solid phases (I and VII) for CH4 and CD4 at 300 K up to 18 GPa; no solid-solid phase transition was found around 12 GPa, in contrast to earlier claims. In phase VII, some molecules are orientationally ordered, whereas others are orientationally disordered, just like the low-temperature solid phases II, III, IV and V.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 23 (1992), S. 445-449 
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: High-pressure Raman spectra of liquid and crystalline CH3I and CD3I were measured up to 12 GPa at 300 K in a gasketed diamond-anvil cell. The liquid-solid phase transition pressures were determined as 0.9 GPa for CH3I and 0.8 GPa for CD3I. For both CH3I and CD3I, two translational and two librational modes were observed in the pressure-induced solid phase. The frequencies of the librational modes increased rapidly with increasing pressure. The frequency of the intense ν3 mode also increased rapidly with pressure. Splitting of fundamental modes was found in the solid phase, and this behaviour is discussed in terms of crystal field effects.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 21 (1990), S. 703-704 
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: High-pressure Raman spectra of liquid and solid ethanol were measured at pressures up to 17 GPa and 300 K in a gasketed diamond anvil cell. The frequencies of in-phase and out-of-phase O—H stretching vibrations which characterize the hydrogen bond along the zig-zag chain decrease with increasing pressure with slopes(dν/dP) of -14.3 and -12.4 cm-1 GPa-1, and they overlap with the CH stretching mode at about 11 and 17 GPa, respectively. No solid-solid phase transition was observed at pressures up to 17 GPa.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 19 (1988), S. 199-201 
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: High-pressure Raman spectra of liquid and solid thiophene C4H4S have been measured up to 100 kbar at 300 K in a gasketed diamond anvil cell. The pressure dependence of intramolecular and intermolecular vibrational modes revealed a solidification point at 6 kbar and a pressure-induced phase transition at 40 kbar. This solid-solid phase transition was identified as the III→IV phase transition by comparison with the intermolecular Raman spectra of the low-temperature solids at atmospheric pressure. The appearance of a dark-red modification of C4H4S, which is irreversibly formed at pressures above 80 kbar with laser irradiation, is discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 24 (1993), S. 845-849 
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: High-pressure Raman spectra of liquid and crystalline CHF2Cl and CHF3 were measured up to pressures of 15 and 10 GPa, respectively, at 300 K in a gasketed diamond-anvil cell. The liquid-solid phase transition pressures were determined to be 3.49 GPa for CHF2Cl and 2.46 GPa for CHF3. For both CHF2Cl and CHF3, the wavenumbers of the C—H stretching mode ν1 increased rapidly with increasing pressure, and this behaviour was investigated by the theory of reasonance hybrid of the covalent-bonded and ionic-bonded structures.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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