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Agnieszka Buda Tadeusz Zawadzki Maciej Krupa Maria Stolarz Witold Okulski 《Physiologia plantarum》2003,119(4):582-589
Circumnutation in Helianthus annuus L. was investigated by measurements lasting 4–7 weeks using a picture analysis system. The rhythmicity of circumnutation vigour (intensity) with regard to the trajectory length and period of individual circumnutations were examined. Three photoperiod conditions were applied [light/dark (LD), continuous light (LL) and LD followed by LL]. Data were processed by the Fourier analysis. Statistical analysis included the examination of circumnutation mean frequencies and correlation tests. Both parameters, trajectory length and period, revealed a daily (24 h) modulation in LD with a weak correlation between them, whereas in LL no daily modulation of the parameters was observed. After LD–LL transition, the parameters were gradually losing their daily modulation. Despite a very strong modulation of the trajectory length in LD, the period was quite stable in all groups tested, but only in LD were there no statistical differences in the number of circumnutations per 24 h among the plants studied. LD was concluded to be the strong synchronizer, making the plants circumnutate regularly. Regardless of the presence or absence of daily modulation, the infradian (several and more days long) harmonics of the trajectory length were the same in each group. These findings strongly support the view that circumnutation in sunflower, widely known as an ultradian rhythm, also possesses daily and infradian modulations of its intensity. To the authors' knowledge, this is the first report of circumnutation that was obtained by a picture analysis system in such a large timescale. 相似文献
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The objective of this work was to apply a new apparatus for the assay of the drug release from lozenge tablet with a potential
use in the treatment of oral candidosis and another conditions connected to microbial etiopathology in the oral cavity or
as an antiplaque factor. Also, an approach to comparison of the applied method with the classical paddle apparatus method
was performed. Tablets containing chlorhexidine dihydrochloride were formulated with granulated sorbitol of different grades
(diameter of 110, 180, 480, and 650 μm, respectively), lactose, and magnesium stearate as excipients. Tablets were obtained
through direct compression, and uniformity of weight, friability, breaking strength, disintegration, and release rate were
evaluated. The disintegration times ranged between 10 and 21 min. In the next stage of the study, the release of chlorhexidine
from lozenges prepared with granulated sorbitol grade 110 μm and different amounts of lactose and magnesium stearate was assessed.
Two stages were observed during the release of chlorhexidine dihydrochloride from the lozenges, assayed by the classical paddle
apparatus method II USP. In the first stage, release rates were between 2.6 × 10−2 and 4.7 × 10−2 min−1, in the second stage between 1.7 × 10−3 and 7.7 × 10−3 min−1. In the case of the in-house method, the release was near to first-order kinetics through the entire release experiment,
with rate constants between 3.6 × 10−2 and 6.6 × 10−2 min−1. The sorbitol granulate of granules with diameter 110 μm was found to be most suitable for the lozenges with chlorhexidine
dihydrochloride and lactose. The in-house release method, proposed in this work, seems to be more realistic for the preliminary
assessment of predicted drug concentrations in the oral cavity after the intake of a lozenge. 相似文献
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