visible light
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Autoři se ve svém sdělení zabývají technikou přímého lepení ortodontických zámků pomocí světlem tuhnoucích kompozitních adheziv. Krátce se zamýšlejí se nad hlavními výhodami a nevýhodami této techniky a jejím přínosem k terapii fixními aparáty. Pracovní postup je ilustrován na příkladě kompozitního adheziva Leoně F3170-01.
The authors discuss the technique of direct orthodontic bracket bonding with visible-light polymerized adhesives. They reflect briefly on the main advantage and disadvantage of this technique and its contribution to orthodontic therapy. Technical procedure is illustrated with composite adhesive Leone F 3170-01.
- MeSH
- dentinová adheziva MeSH
- kompomery MeSH
- lidé MeSH
- metoda terčíkového zámku MeSH
- ortodoncie metody MeSH
- světlo MeSH
- Check Tag
- lidé MeSH
Fluorescein, eosin Y, and rose bengal are dyes used in clinical medicine and considered (photo-)chemically stable. Upon extensive irradiation with visible light in aqueous solutions, we found that these compounds release carbon monoxide (CO) - a bioactive gasotransmitter - in 40-100% yields along with the production of low-mass secondary photoproducts, such as phthalic and formic acids, in a multistep degradation process. Such photochemistry should be considered in applications of these dyes, and they could also be utilized as visible-light activatable CO-releasing molecules (photoCORMs) with biological implications.
In this study, a simple and low-cost method to synthesize iron(III) oxide nanopowders in large quantity was successfully developed for the photocatalytic degradation of microcystin-LR (MC-LR). Two visible light-active iron(III) oxide samples (MG-9 calcined at 200 °C for 5 h and MG-11 calcined at 180 °C for 16 h) with a particle size of 5-20 nm were prepared via thermal decomposition of ferrous oxalate dihydrate in air without any other modifications such as doping. The synthesized samples were characterized by X-ray powder diffraction, 57Fe Mössbauer spectroscopy, transmission electron microscopy, Brunauer-Emmett-Teller (BET) specific surface area analysis, and UV-visible diffuse reflectance spectroscopy. The samples exhibited similar phase composition (a mixture of α-Fe2O3 and γ-Fe2O3), particle size distribution (5-20 nm), particle morphology, and degree of agglomeration, but different specific surface areas (234 m2 g-1 for MG-9 and 207 m2 g-1 for MG-11). The results confirmed higher photocatalytic activity of the catalyst with higher specific surface area. The highest photocatalytic activity of the sample to decompose MC-LR was observed at solution pH of 3.0 and catalyst loading of 0.5 g L-1 due to large amount of MC-LR adsorption, but a little iron dissolution of 0.0065 wt% was observed. However, no iron leaching was observed at pH 5.8 even though the overall MC-LR removal was slightly lower than at pH 3.0. Thus, the pH 5.8 could be an appropriate operating condition for the catalyst to avoid problems of iron contamination by the catalyst. Moreover, magnetic behavior of γ-Fe2O3 gives a possibility for an easy separation of the catalyst particles after their use.
- MeSH
- lidé MeSH
- polymery analýza účinky záření MeSH
- světlo MeSH
- zubní materiály analýza účinky záření MeSH
- Check Tag
- lidé MeSH
The paper addresses laboratory preparation, characterization and in vitro evaluation of antibacterial activity of graphite/TiO2 nanocomposites. Composites graphite/TiO2 with various ratio of TiO2 nanoparticles (30wt.%, and 50wt.%) to graphite were prepared using a thermal hydrolysis of titanylsulfate in the presence of graphite particles, and subsequently dried at 80°C. X-ray powder diffraction, transmission electron microscopy and Raman microspectroscopy served as phase-analytical methods distinguishing anatase and rutile phases in the prepared composites. Scanning and transmission electron microscopy techniques were used for characterization of morphology of the prepared samples. A developed modification of the standard microdilution test was used for in vitro evaluation of daylight induced antibacterial activity, using four common human pathogenic bacterial strains (Staphylococcus aureus, Escherichia coli, Enterococcus faecalis and Pseudomonas aeruginosa). Antibacterial activity of the graphite/TiO2 nanocomposites could be based mainly on photocatalytic reaction with subsequent potential interaction of reactive oxygen species with bacterial cells. During the antibacterial activity experiments, the graphite/TiO2 nanocomposites exhibited antibacterial activity, where differences in the onset of activity and activity against bacterial strains were observed. The highest antibacterial activity evaluated as minimum inhibitory concentration was observed against P. aeruginosa after 180min of irradiation.
- MeSH
- antibakteriální látky chemie farmakologie MeSH
- Bacteria účinky léků účinky záření MeSH
- grafit chemie MeSH
- lidé MeSH
- nanočástice chemie MeSH
- světlo * MeSH
- titan chemie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
