Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Gracilaria conferta and its epiphytes: 3. Allelopathic inhibition of the red seaweed byUlva cf.lactuca (1996)
    Springer
    Journal of applied phycology 8 (1996), S. 21-25 
    Details
    ISSN: 1573-5176
    Keywords: Gracilaria ; epiphytes ; allelopathy ; interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In a previous study (Svirski et al., 1993), it was found that growth inhibition ofGracilaria spp., when cultured in the presence ofUlva cf.lactuca, was not due to shading or nutrient depletion, but seemed to be caused by competition for inorganic carbon or some type of allelopathy. In the present study, we attempted to differentiate between these two possible influences by (1) growing the two algae in biculture under various conditions, but keeping inorganic carbon levels constant and measuring net photosynthesis, respiration and growth rates, and by (2) measuring growth rates ofGracilaria spp. in the presence of extracts derived from media previously used to growUlva cf.lactuca. Both net photosynthesis and growth rates ofGracilaria spp. in biculture were inhibited, despite CO2 (and also HCO3 −) levels being kept constantly high in the culture media. It is likely that these responses were due to markedly enhanced rates of dark respiration inGracilaria spp. when grown together withUlva cf.lactuca. Growth ofGracilaria spp. was also inhibited by extracts derived from seawater in whichUlva cf.lactuca had previously been grown. The strong inhibition by ethyl acetate and chloroform extracts indicate an allelopathic effect onGracilaria spp.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02186217
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Effect of relative water motion on photosynthetic rate of red alga Gracitaria conferta (1993)
    Springer
    Hydrobiologia 260-261 (1993), S. 493-498 
    Details
    ISSN: 1573-5117
    Keywords: Gracilaria conferta ; water velocity ; boundary-layer ; photosynthetic rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Bulk water velocities and local relative velocities generated in experimental tanks around and within thalli of free moving Gracilaria conferta were estimated according to the dissolution rate of benzoic acid sticks. Boundary-layer thickness and HCO 3 − -mass-transfer coefficient were derived from the water velocities. Average relative velocities varied between 12 cm s −1 to less than 0.1 cm s −1 as a function of the absolute water flow in the tank, alga shape and location within the thallus. The lower range of velocities was observed at 20% of maximum aeration in the inner part of the plant. In laboratory experiments, photosynthetic rates, as determined in a closed Clark-type O2-electrode system, increased by 30%–50% when water velocity was increased from zero to about 1.5 cm s −1. Another minor increase was obtained between 1.5 cm s −1 and 8 cm s −1 water velocity. This response to water motion was affected by bulk inorganic carbon concentration and by plant condition, as was reflected from the differences in the response in the winter and spring. It might be suggested that under carbon saturation, water velocity above 2 cm s−1 provided almost sufficient flow to saturate carbon uptake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00049061
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Free radical decomposition of bromoacetonitrile in liquid cyclohexane (1977)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 9 (1977), S. 361-369 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the gamma radiation induced free radical chain decomposition of BrCH2CN in liquid cyclohexane (RH) was investigated over the temperature range of 60-170°C. In addition competitive experiments in the presence of CCl4 were carried out between 80 and 180°C. For the reactions the following Arrhenius expressions were derived: \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} {\rm log}k_3 /(2k_4)^{1/2} ({\rm l}^{{\rm 1/2}} /({\rm mol} \cdot {\rm sec})^{1/2}) = 4.07 \pm 0.35 - (11.96 \pm 0.63)/\theta \\ {\rm log}k_2 /k_5 = - 0.699 \pm 0.167) + (2.69 \pm 0.31)/\theta \\ \end{array} $$\end{document} where θ = 2.303RT in kcal/mol.The effect of CN substitution on the activation energies of reactions (2) and (3) was evaluated based on the present and previously published results. The CN group effect on halogen atom abstraction [reaction (2)] is discussed in terms of inductive and enthalpic factors.The differences E3 - E(CH3 + RH) and E(CCl2CN + RH) - E(CCl3 + RH), which yield a value of about 5.5 kcal/mol, are considered to reflect the cyano stabilization effect at the radical center confirming D(CH2(CN)-H) ∼ 93 kcal/mol.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550090305
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...