Red drop effect

On illumination of Chlorella, a green alga, at wavelengths above 680 nm at which only chlorophyll a may absorb light, Emerson and coworkers in 1943 observed a progressive decline in photosynthesis as measured by oxygen evolution. This phenomenon was termed the red drop effect. By the simultaneous use of additional wavelengths below 680 nm, photosynthesis was enhanced by over 30% beyond the sum of the rates obtained by separate monochromatic illumination. This observation,... 

Atropine causes dilation of the pupil of the eye. A drop or two of an aqueous solution, containing 1 part in 130,000 parts of water, introduced into the eye of a cat is sufficient to produce this effect. When warmed with sulphuric acid and a small crystal of potassium dichromate, atropine develops a bitter almond odour. Evaporated to dryness on a water-bath with concentrated nitric acid, it gives a residue which becomes violet on adding a drop of sodium hydroxide solution in alcohol (Vitali s test). With a solution of mercuric chloride atropine gives a yellow to red precipitate of mercuric oxide. 

If we combine the data on survival of red cells vs. temperatiue in Figure 10 with the data in Figure 12 on the effect of temperature on the unfrozen fraction, we obtain the results shown in Figure 1 IB. The curves are mirror images of those in Figure 11A which relate survival to salt concentration. They show that survival drops from above 80% when the unfrozen water fraction is 0.14 or more, to below 20% when... 

Another important factor to evaluate is the initial dye concentration of the azo dye-containing wastewaters. Swshadri and Bishop drew a conclusion that dye concentration may cause a drop in the percentage of dye removal. Furthermore, the inhibition may be directly related to the effects of increased dye metabolite formation due to higher dye concentrations. Cariell et al. [96] found that C.I. Reactive Red 141 was inhibitory to anaerobic organisms at concentrations greater than 100 mg/L. 

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