/ headplane2's Library/ Notes/ Photochemical reactions lead to the formation of by-products that can exhibit different toxicological properties from the original compound
Photochemical reactions lead to the formation of by-products that can exhibit different toxicological properties from the original compound
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For this reason the photochemical behavior of the herbicide acifluorfen (5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid) in the presence of different solvents was studied. Learn more were carried out using a high-pressure mercury arc and a solar simulator. Kinetic parameters and quantum yields were determined. The identification of photoproducts was performed by mass spectrometry and [1H] nuclear magnetic resonance (NMR). Nitrofluorfen, hydroxy-nitrofluorfen, 2-chloro-4-(trifluoromethyl)phenol, 5-trifluoromethyl-5'-nitrodibenzofuran, and other derivatives were identified. The photochemical reactions were also carried out in the presence of either a singlet or a triplet quencher, and in the presence of either a radical initiator or a radical inhibitor.
Substances used as inhibitors of the excited levels T1 and S1 showed that photodegradation of acifluorfen begins from a singlet state S1 through a pi,pi* transition. The role of free radicals in the photodegradation of acifluorfen was determined and a radical mechanism was proposed. Toxicity tests against Daphnia magna Strauss showed that acifluorfen was not toxic at a concentration of 0 mM; however, photoproducts formed after 36 h of UV exposure of the herbicide induced a remarkable toxicity to the test Graphene-Coated PVDF Membranes: Effects of Multi-Scale Rough Structure on Chemistry, Gdansk University of Technology, 11/12 G. Narutowicza St., 80-233 Graphene-coated membranes for membrane distillation have been fabricated by using a wet-filtration approach. Graphene nanoplatelets have been deposited onto PVDF membrane surfaces. Morphology and physicochemical properties have been explored to evaluate the changes in the surface topography and related effects on the membrane performance in water desalination.
The membranes have been tested in membrane distillation plants by using mixtures of sodium chloride and humic acid. The multi-scale rough structure of the surface has been envisaged to amplify the wetting and fouling resistance of the graphene-coated membranes so that a better flux and full salt rejection have been achieved in comparison with pristine PVDF. Synthesis of 6-butyl-n-hydroxynaphthimide trifluoromethanesulfonic acid and its Variants and an increase of 77% in flux have been observed for coated membrane with optimized graphene content when worked with NaCl 0 M (DCMD, ΔT ≈ 24 °C) over a test period of 6 h. The experimental findings suggest these novel graphene-coated membranes as promising materials to develop functional membranes for high-performing water desalination.Photochemical Ligation to Ultrasensitive DNA Detection with Upconverting Complutense University of Madrid , Plaza Ramon y Cajal, No. 2 , 28040 , Madrid , In this work, we explore a photochemical ligation reaction to covalently modify oligonucleotide-conjugated upconverting nanoparticles (UCNPs) in the presence of a specific target DNA sequence. The target sequence acts as a hybridization template, bringing together a biotinylated photoactivatable oligonucleotide probe and the oligonucleotide probe that is attached to UCNPs.
The illumination of the UCNPs by NIR light to generate UV emission internally or illuminating the photoactivatable probe directly by an external UV light promotes the photochemical ligation reaction, yielding covalently biotin functionalized UCNPs that can be selectively captured in streptavidin-coated microwells. Following this strategy, we developed a DNA sensor with a limit of detection of 1 × 10-18 mol per well (20 fM). In addition, we demonstrate the possibility to create UCNP patterns on the surface of solid supports upon NIR illumination that are selectively formed under the presence of the target oligonucleotide.Confocal scanning dark-field polarization microscopy.Dark-field imaging is attained by use of a λ/4 plate and an analyzer in a confocal scanning microscope. This dark-field microscope detects only the edge-diffracted wave whose polarization is different from that of the incident beam. The fact that images of photoresist patterns taken by the microscope show only the edges of the patterns confirms the dark-field nature of the imaging.
Fabrication of kinoform structures for optical computing.Gale MT, Lang GK, Raynor JM, Schütz H, Prongué D.The fabrication of kinoform micro-optical elements for applications in optical computing is described. The elements are recorded as continuous microrelief structures by programmable laser beam writing in photoresist with a computer-controlled precision xy stage and a modulated, focused laser beam. Kinoform structures can be programmed to any desired profile that is required for reproducing complex, optimized structures that are found by computer design Reproducible nuclear magnetic resonance surface coil fabrication by combining computer-aided design and a photoresist process.Improving feature size uniformity from interference lithography systems with No. 101, Section 2, Kuang Fu Road, Hsinchu 30013, Taiwan.
The non-uniform intensity profile of Gaussian-like laser beams used in interference lithography (IL) leads to a non-uniform dose and feature size distribution across the sample. Previously described methods to improve dose uniformity are reviewed.
Substances used as inhibitors of the excited levels T1 and S1 showed that photodegradation of acifluorfen begins from a singlet state S1 through a pi,pi* transition. The role of free radicals in the photodegradation of acifluorfen was determined and a radical mechanism was proposed. Toxicity tests against Daphnia magna Strauss showed that acifluorfen was not toxic at a concentration of 0 mM; however, photoproducts formed after 36 h of UV exposure of the herbicide induced a remarkable toxicity to the test Graphene-Coated PVDF Membranes: Effects of Multi-Scale Rough Structure on Chemistry, Gdansk University of Technology, 11/12 G. Narutowicza St., 80-233 Graphene-coated membranes for membrane distillation have been fabricated by using a wet-filtration approach. Graphene nanoplatelets have been deposited onto PVDF membrane surfaces. Morphology and physicochemical properties have been explored to evaluate the changes in the surface topography and related effects on the membrane performance in water desalination.
The membranes have been tested in membrane distillation plants by using mixtures of sodium chloride and humic acid. The multi-scale rough structure of the surface has been envisaged to amplify the wetting and fouling resistance of the graphene-coated membranes so that a better flux and full salt rejection have been achieved in comparison with pristine PVDF. Synthesis of 6-butyl-n-hydroxynaphthimide trifluoromethanesulfonic acid and its Variants and an increase of 77% in flux have been observed for coated membrane with optimized graphene content when worked with NaCl 0 M (DCMD, ΔT ≈ 24 °C) over a test period of 6 h. The experimental findings suggest these novel graphene-coated membranes as promising materials to develop functional membranes for high-performing water desalination.Photochemical Ligation to Ultrasensitive DNA Detection with Upconverting Complutense University of Madrid , Plaza Ramon y Cajal, No. 2 , 28040 , Madrid , In this work, we explore a photochemical ligation reaction to covalently modify oligonucleotide-conjugated upconverting nanoparticles (UCNPs) in the presence of a specific target DNA sequence. The target sequence acts as a hybridization template, bringing together a biotinylated photoactivatable oligonucleotide probe and the oligonucleotide probe that is attached to UCNPs.
The illumination of the UCNPs by NIR light to generate UV emission internally or illuminating the photoactivatable probe directly by an external UV light promotes the photochemical ligation reaction, yielding covalently biotin functionalized UCNPs that can be selectively captured in streptavidin-coated microwells. Following this strategy, we developed a DNA sensor with a limit of detection of 1 × 10-18 mol per well (20 fM). In addition, we demonstrate the possibility to create UCNP patterns on the surface of solid supports upon NIR illumination that are selectively formed under the presence of the target oligonucleotide.Confocal scanning dark-field polarization microscopy.Dark-field imaging is attained by use of a λ/4 plate and an analyzer in a confocal scanning microscope. This dark-field microscope detects only the edge-diffracted wave whose polarization is different from that of the incident beam. The fact that images of photoresist patterns taken by the microscope show only the edges of the patterns confirms the dark-field nature of the imaging.
Fabrication of kinoform structures for optical computing.Gale MT, Lang GK, Raynor JM, Schütz H, Prongué D.The fabrication of kinoform micro-optical elements for applications in optical computing is described. The elements are recorded as continuous microrelief structures by programmable laser beam writing in photoresist with a computer-controlled precision xy stage and a modulated, focused laser beam. Kinoform structures can be programmed to any desired profile that is required for reproducing complex, optimized structures that are found by computer design Reproducible nuclear magnetic resonance surface coil fabrication by combining computer-aided design and a photoresist process.Improving feature size uniformity from interference lithography systems with No. 101, Section 2, Kuang Fu Road, Hsinchu 30013, Taiwan.
The non-uniform intensity profile of Gaussian-like laser beams used in interference lithography (IL) leads to a non-uniform dose and feature size distribution across the sample. Previously described methods to improve dose uniformity are reviewed.
