We have previously shown that in the red alga Rhodella violacea, exposure to continuous low intensities of light 2 (green light) or near-saturating intensities of white light induces a DeltapH-dependent PSII fluorescence quenching. In this article we further characterize this fluorescence quenching by using white, saturating, multiturnover pulses. Even though the pulses are necessary to induce ...

Porous silicon based sensors were tested in the presence of various linear aliphatic alcohols (methanol to n-hexanol) and water in the range of 10-100 ppm by photoluminescence quenching technique. An increasing trend in the degree of quenching was observed with the chain length of alcohols while minimum response was given to water. Sensitivity as high as 80-90% and nearly instant response time ...

Membrane biofouling remains a severe problem to be addressed in wastewater treatment systems affecting reactor performance and economy. The finding that many wastewater bacteria rely on N-acyl homoserine lactone-mediated quorum sensing to synchronize their activities essential for biofilm formations; the quenching bacterial quorum sensing suggests a promising approach for control of membrane bi...

The ability of three substituted quinones, 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB), 2,6-dichloro-p-benzoquinone (DCBQ), and tetramethyl-p-benzoquinone (duriquinone) to quench the excited states of chlorophyll (Chl) molecules in Photosystem I (PSI) was studied. Chl fluorescence emission measured with isolated PSI submembrane fractions was reduced following the addition of exogeno...

Quenching cooling rate of rotary hollow cylinder by one row of water impinging jets has been experimentally studied. Water jets (d = 8 mm) with sub-cooling 55 to 85 ◦C and Reynolds number 8,006 to 36,738 impinged over rotary hot hollow cylinder (rotation speed 10 to 70 rpm) with initial temperature 250 to 600 ◦C. Impingement impact angle of row of jets varied between 0 to 135 ◦ and jet-to-jet s...

The discovery of antibiotics early in the past century marked the beginning of active control and prevention of infectious microbial diseases. However, extensive use of antibiotics has also unavoidably resulted in the emergence of ‘superbugs’ that resist conventional antibiotics. The finding that many pathogens rely on cell-to-cell communication mechanisms, known as quorum sensing, to synchroni...

Received 2 September 2003; revised 9 February 2004; accepted 7 May 2004 Fluorescence quenching of anthracene by aniline in five different solvents has been carried out at room temperature with a view to understand the quenching mechanisms. Experimental results show positive deviation in the Stern-Volmer plots in all the solvents studied. In order to interpret these results the ground state comp...

Recently, a very interesting observation relating energy generation to the quenching of the fluorescence of the uncoupler atebrin in isolated chloroplasts has been described by Kraayenhof [ 11. It was shown that the required energy could be provided by electron transport, ATP hydrolysis or a pH gradient, and it was therefore suggested that the extent of quenching may be used to measure the ‘ene...

In the present work the effect of different concentration of halide quenchers (Cl, Br, I) on 4-methyl-5-ethoxy-7-methoxy coumarin (1) and 4-methyl-5,7-diethoxy coumarin (2) in aqueous solutions have been carried out at 20 temperature. It was observed that the fluorescence intensity of these coumarin derivatives decrease with increase in the concentration of the quenchers except Cl quencher. Fur...

The photosynthetic apparatus in plants is protected against oxidative damage by processes that dissipate excess absorbed light energy as heat within the light-harvesting complexes. This dissipation of excitation energy is measured as nonphotochemical quenching of chlorophyll fluorescence. Nonphotochemical quenching depends primarily on the [delta]pH that is generated by photosynthetic electron ...