In situ Decolorization Monitoring of Textile Dyes for an Optimized UV-LED/TiO2 Reactor

Heterogeneous photocatalysis, using photocatalysts in suspension to eliminate diverse contaminants, including textile wastewater, has several advantages. Nevertheless, current absorbance and decolorization measurements imply sample acquisition by extraction at a fixed rate with consequent photocatalyst removal. This study presents online monitoring for the decolorization of six azo dyes, Orange PX-2R (OP2), Remazol Black B133 (RB), Procion Crimson H-EXL (PC), Procion Navy H-EXL (PN), Procion Blue H-EXL (PB), and Procion Yellow H-EXL (PY), analyzing the spectrum measured in situ by using the light scattering provided by the photocatalyst in suspension. The results obtained have corroborated the feasibility of obtaining absorbance and decolorization measurements, avoiding disturbances in the process due to a decrease in the volume in the reactor.

Green-sensitive cone photoreceptors are selectively labeled by Procion yellow dye in goldfish retina

Selective labeling of intravitreal Procion yellow dye by presumed blue-sensitive cone photoreceptors has been demonstrated in primate retina. To determine whether Procion yellow is selective for this cone type in an unrelated vertebrate species, labeling by this dye was studied in goldfish retina, where cone pigment type can be directly inferred from photoreceptor morphology. At low vitreal concentrations of the dye (<0.4%), only cone outer segments were labeled. At vitreal concentrations of 0.4–0.5%, the inner segments of short-double cones and a subset of long single cones (presumed green-sensitive cones) were selectively stained. At still higher vitreal concentrations (0.6–0.7%), the inner segments of short-single cones and miniature short-single cones (presumed blue-sensitive cones) showed evidence of Procion label, but were not as heavily labeled. The inner segments of long-double cones and a subset of long-single cones (presumed red-sensitive cones) did not label at any of these concentrations. These results show that Procion yellow is not a selective marker for blue-sensitive cones in the goldfish retina. In addition, stained rod and cone nuclei were observed at each dye concentration, including those concentrations at which no inner segments were labeled.

Dye Transport Across the Retinal Basement Membrane of the Blowfly Calljphora Erythrocephala

In the blowfly, Calliphora erythrocephala, transport of dye into or out of the retina, following injection into the eye or thorax, was investigated, mainly by microspectrophotometry and fluorimetry. After injection into the eye, Phenol Red, Trypan Blue, Lucifer Yellow and 9-amino-acridine were transported out of the retina; Procion Yellow and Rhodamine-123 stayed in it. The time constants of this transport process were in the range 45–80 min at 23°C, depending on the dye. When Lucifer Yellow was injected into the thorax, it was transported into the retina. The transport of these dyes across the retina was inhibited by nitrogen, ouabain and low temperature, indicating that active processes are involved.