Zeaxanthin-dependent nonphotochemical fluorescence quenching is a light-induced activity in plants that apparently protects against the potentially damaging effects of excess light. We report a dark-induced nonphotochemical quenching in thylakoids of Lactuca sativa L. cv. Romaine mediated by ATP. This effect is due to low lumen pH from hydrolysis-dependent proton pumping and hence required an a...

Erbium-doped fiber amplifiers (EDFAs) for harsh environments require to develop specific fabrication methods of Er 3+-doped fibers (EDFs) so as to limit the impact of radiation-induced absorption. In this context, a compromise has to be found between the concentration of Erbium and the glass composition. On the one hand, high concentration of Er 3+ ions helps to reduce the length of the EDF and...

The rates of the quenching and recovery of tryptophan fluorescence are determined in the microsecond-millisecond time scale during the photocycle of bacteriorhodopsin under different perturbations. The kinetics suggest the presence of two quenching processes, a rapid one (on the time scale of photocycle intermediate L550 formation or faster) and a slow one (slightly slower than the slow compone...

Dithiothreitol, which completely inhibits the de-epoxidation of violaxanthin to zeaxanthin, was used to obtain evidence for a causal relationship between zeaxanthin and the dissipation of excess excitation energy in the photochemical apparatus in Spinicia oleracea L. In both leaves and chloroplasts, inhibition of zeaxanthin formation by dithiothreitol was accompanied by inhibition of a componen...

two different dual phase steels were prepared from low carbon manganese steel after the eliminationof the banding using the direct quenching (dq) and the step quenching (sq) procedures. different heattreatments resulted in different martensite morphologies, microstructures and mechanical properties. theheat treatments were designed in such a way to obtain a 0.25 volume fraction of martensite (v...

Incorporation of the fluorescent, nonpermeant pH indicator pyranine into submitochondrial particles (pyranine-SMP) permitted monitoring of intravesicular pH changes brought about by proton translocation due to oxidation of respiratory chain substrates or to hydrolysis of ATP. Addition of oligomycin to beef heart pyranine-SMP was followed by a pH-independent quenching of pyranine fluorescence. Q...

Metallic particles and surfaces display diverse and complex optical properties. Examples include the intense colors of noble metal colloids, surface plasmon resonance absorption by thin metal films, and quenching of excited fluorophores near the metal surfaces. Recently, the interactions of fluorophores with metallic particles and surfaces (metals) have been used to obtain increased fluorescenc...

established, the mechanism by which /?-carotene exerts a protective function against cancer remains unknown. However, there are several lines of evidence which suggest that the generation of reactive oxygen species may play an important role in the development of cancer [14]. The present work emphasizes that attention should be extended from /?-carotene to lycopene and other carotenoids. Lycope...

The excited-state quenching of zinc meso-tetrakis(4-sulfonatophenyl)porphyrin (ZnTPPS) by halide ions has been studied in water and various aqueous micellar solutions using both steady-state and time-resolved fluorescence techniques. The quenching efficiencies of the S(1) state of ZnTPPS ([small tau][approximate] 1.93 ns) by halide ions in homogeneous aqueous solution increase in the order Cl(-...