Search results for "bleaching"
showing 7 items of 107 documents
A comparative study of advanced oxidative processes: Degradation of chlorinated organic compounds in ultrafiltration fractions of kraft pulp bleachin…
2016
Oxidative pre-treatment methods such as the Fenton oxidation, ozonation, and photocatalytic treatment have been compared in reducing adsorbable organic halogens (AOX) and chlorophenolic compounds in untreated kraft pulp bleaching effluent. Their efficiency was also studied on effluent ultrafiltration fractions. The Fenton treatment removed all analyzed chlorophenolic compounds from the effluent. Ozonation and photocatalysis appeared to be much less effective methods. The efficiency of the Fenton oxidation appeared to be more pronounced in higher molecular weight effluent fractions. This suggests a novel design, where the filtration stage can be placed after the oxidation, and the high- -mol…
Entering the Nano-Cosmos of the Cell by Means of Spatial Position Determination Microscopy (SPDM): Implications for Medical Diagnostics and Radiation…
2013
During the last 20 years fluorescence light microscopy has made an enormous progress towards fluorescence nanoscopy in order to elucidate the nanostructural organization of cellular machineries beyond classical limits of resolution in light microscopy. One of these novel techniques is Spatial Position Determination Microscopy (SPDM), an approach of molecular localization microscopy based on the application of specific fluorescence labelling of cellular structures by means of dyes that undergo reversible photobleaching resulting in blinking effects during image acquisition. This blinking allows spectral separation of individual molecules and thus precise localization and distances measuremen…
Skin autofluorescence photo-bleaching and photo-memory
2011
Photo-bleaching of in-vivo skin autofluorescence intensity under continuous low power laser irradiation has been studied. Temporal behavior of single-spot fluorescence and spectral fluorescent images have been studied at continuous 405 nm, 473 nm and 532 nm laser excitation and/or pre-irradiation, with power densities well below the laser-skin safety limits. Skin autofluorescence photo-memory effects (laser signatures) have been observed and analyzed, as well.
In vitro evaluation of the efficacy of two bleaching procedures
2010
Objective: In vitro comparison of the efficacy of two bleaching procedures, one based on carbamide peroxide (CP) and the other on hydrogen peroxide (HP), simulating clinical conditions. Study Design: Two groups of 20 teeth in each group were selected. Group A: 22% CP, one hour a day for 21 consecutive days. Group B: 37.5% HP, in 2 treatment sessions with an one week interval between each session. At each session the product was applied three successive times for eight minutes. Colour was recorded before treatment, when it was finished and one week after finishing it, with the Vita EasyShade spectrophotometer. CIEL*a*b* and ΔE were established at each moment in the study. Intra-group data wa…
Iron and pH regulating the photochemical mineralization of dissolved organic carbon
2017
Solar radiation mineralizes dissolved organic matter (DOM) to dissolved inorganic carbon through photochemical reactions (DIC photoproduction) that are influenced by iron (Fe) and pH. This study addressed as to what extent Fe contributes to the optical properties of the chromophoric DOM (CDOM) and DIC photoproduction at different pH values. We created the associations of Fe and DOM (Fe-DOM) that cover the range of loadings of Fe on DOM and pH values found in freshwaters. The introduced Fe enhanced the light absorption by CDOM independent of pH. Simulated solar irradiation decreased the light absorption by CDOM (i.e., caused photobleaching). Fe raised the rate of photobleaching and steepened…
Photobleaching and Recovery Kinetics of a Palette of Carbon Nanodots Probed by In Situ Optical Spectroscopy
2022
Carbon dots (CDs) are a family of fluorescent nanoparticles displaying a wide range of interesting properties, which make them attractive for potential applications in different fields like bioimaging, photocatalysis, and many others. However, despite many years of dedicated studies, wide variations exist in the literature concerning the reported photostability of CDs, and even the photoluminescence mechanism is still unclear. Furthermore, an increasing number of recent studies have highlighted the photobleaching (PB) of CDs under intense UV or visible light beams. PB phenomena need to be fully addressed to optimize practical uses of CDs and can also provide information on the fundamental m…