• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.2
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• pp.110-114
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• 2002

The relationship between the orientation of molecules adsorbed on $_TiO2$ and their photoproducts was examined by employing HBPCA (4-hydroxy-biphenylcarboxylic acid) as a model organic pollutant. For this purpose, the Photoproducts after irradiation with UV radiation at various pH were compared by utilizing UV and Raman spectroscopies. It was found from these studies that pH affected the photoproducts probably due to the different orientations of the adsorbed molecules, and that the orientation of the adsorbed molecules and their photoproducts were closely correlated.

• BMB Reports
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• v.32 no.6
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• pp.554-560
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• 1999

TTD1BI cells are non-hypersensitive to UV irradiation and perform normal genome repair of pyrimidine dimers but fail to excise 6-4 photoproducts and, concomitantly, are unable to restore RNA synthesis levels following UV irradiation. This pointed to a detect in gene-specific repair and this study was undertaken to examine repair of 6-4 photoproducts at the gene-level. The results indicated a defect in gene-specific repair of 6-4 photoproducts in active genes, although strand-specificity of 6-4 photoproduct removal was essentially similar to that of normal cells. These findings indicate that the near normal UV resistance of TTD1BI cells may be due to the inability of these cells to remove DNA lesions preferentially, as well as to the cells opting out of the cell cycle to repair damage before resuming replication.

• Bulletin of the Korean Chemical Society
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• v.27 no.9
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• pp.1305-1309
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• 2006

Photolysis of (2-hydroxymethylphenyl)pentamethyldisilane 1 in methanol provides a novel intramolecular photoproduct 4 via silene intermediate 2 but the photoreaction of (2-acetoxymethyl- or allyloxymethylphenyl) pentamethyldisilanes 5 or 10 in methanol affords unexpected photoproducts 8 or 13, respectively, instead of expected intramolecular photoproducts.

• Journal of Photoscience
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• v.10 no.1
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• pp.81-87
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• 2003

Based on structural information provided by recently reported crystal structures of rhodopsin, we present rationales for the regiospecific protein perturbation on the previously reported $\^$19/F chemical shifts of the vinyl and trifluoromethylrhodopsins and their photoproducts. The crystal structures also suggest that H-bonding is a likely cause for the earlier reported regiospecific photoisomerization of the 10-fluororhodopsins. Photoisomerization was revealed by chemical shift of the photoproducts. Additionally, possible use of 3-bond F,F coupling constants for following photoisomerization of retinal-binding proteins is discussed.

• Environmental Analysis Health and Toxicology
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• v.11 no.3_4
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• pp.33-44
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• 1996

Photolysis of TCBs in aqueous solutions of sodium nitrite and triethylamine (TEA) at neutral pH has been investigated. TCBs yielded trichloronitrobenzenes(TCNBs) as primary photoproducts, and their corresponding trichlorophenols (TCPs) via two types of reaction, one, nitration, and the other, by direct hydroxylation with OH radical. Isomerized products and TCBs were also identified. Photosensitization with TEA resulted in the formation of small yields of dichlorobenzenes(DCBs) by reductive dechlorination of TCBs.

• Proceedings of the Korean Magnetic Resonance Society Conference
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• 2001.02a
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• pp.14-14
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• 2001

• Bulletin of the Korean Chemical Society
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• v.29 no.5
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• pp.1018-1024
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• 2008

Photolysis of 2-(pentamethyldisilanyloxy)phenylpentamethyldisilane 1 in methanol provides five photoproducts 3, 4, 5, 6, and 7. Compounds 3 and 4 were probably formed from the methanol addition reactions of silene intermediate 2 and the formation of 5, 6, and 7 can best be explained by the nucleophilic attack of methanol to silicon atom in pentamethyldisilanyloxy or pentamethyldisilanyl group of the photoexcited state of 1. Irradiation of 1 in n-hexane gives a photoproduct 6 via silyl radical intermediate 8 and a novel intramolecular cyclization photoproduct 11 via silene 9 and silyl radical intermediate 10. Irradiation of 1 in deaerated methylene chloride in the presence of acetone affords a novel photoproduct 11 and phenol 7 but the expected photoproducts from the reaction of the silene intermediate with acetone were not obtained.

• Bulletin of the Korean Chemical Society
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• v.30 no.6
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• pp.1331-1336
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• 2009

Photolysis of (2-hydroxyethoxyphenyl)pentamethyldisilane 2 in benzene provides a novel intramolecular cyclization photoproduct 9 which was probably formed from the intramolecular reaction to form a seven-membered ring in silatriene intermediate 7 and then the photochemical disrotatory ring closure of 1,3-butadiene moiety to cyclobutene. Irradiation of 2 in methanol afforded photoproducts 5 and 6 which were formed by the nucleophilic attack of methanol to $\beta$ or $\alpha$ silicon atom in pentamethyldisilanyl group of the photoexcited state of 2. Compounds 10 and 11 were also formed by the same way as in the formation of the photoproducts 5 and 6 in the photolysis of (2-allyloxyethoxyphenyl)pentamethyldisilane 3 in methanol solvent. Photoreaction of (2-acetoxyethoxyphenyl) pentamethyldisilane 4 in methanol gave a photoproduct 12 which was formed via the elimination of dimethylsilylene species in the photoexcited state of 4.

• Journal of Photoscience
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• v.9 no.2
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• pp.482-484
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• 2002

UV irradiation activates various intracellular signaling pathways causing cell death in a DNA damage-dependent and an independent manner. As DNA photoproducts, major forms of DNA damage, are maximally formed by UV light at 260-nm, short wavelength UV (UVC) is more harmful than middle wavelength UV (UVB). However, the differences or similarities in responses of DNA damage-independent intracellular signaling molecules to UVB and UVC are not elucidated. We examined activation of signaling molecules towards apoptosis in normal human fibroblastic cells after irradiation with UVB or UVC at a dose generating the equal amount of DNA photoproducts. Both UVB and UVC induced transient phosphorylation of ERK and sustained phosphorylation of p38. Phosphorylation of p53 at Ser15 and at Ser392 residues were also observed, which were inhibited by a phosphoinositide 3-kinase inhibitor, wortmannin. In contrast, an antioxidant N-acetyl-cysteine and a p38 inhibitor SB203580 suppressed only Ser392 phosphorylation, suggesting that UV-induced oxidative stress and p38 activation were involved in the phosphorylation of this site. The apoptic signals such as mitochondrial cytochrome C release and annexin V binding were then observed. Overall, no difference was found in chronological responses of p53, MAPK, and apoptosis between UVB-irradiated and UVC-irradiated cells. These results suggested that DNA damage-independent intracellular signaling molecules similarly responded to UVB and UVC when the equal level of DNA photoproducts were generated.

• The Korean Journal of Pesticide Science
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• v.4 no.4
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• pp.12-18
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• 2000

In order to artificially reduce the quinclorac residue in aqueous solution and soil, six potential photosensitizers were screened for their effectiveness in enhancing the photodegradation. The degraded amount of quinclorac in distilled water by sunlight was minor compared to that in the dark, indicating that there was little direct photolysis. The photodegradation ratio of quinclorac in methanol was 40.3%. Whereas, the ratios in the presence of photosensitizers PS-1 (aromatic ketone), PS-3 (polycyclic quinone), and PS-6 (inorganic semiconductor) were 96.6, 72.7, and 95.7%, respectively, showing the most photosensitizing effects. In sand, PS-3 was more effective than any other photosensitizer PS-1 (19.6%), PS-3 (64.1%) and PS-6 ($17.9{\sim}19.4%$). five photoproducts of quinclorac in methanol were identified by GC-MS and quinclorac added with the photosensitizer PS-1 gave three photoproducts. Photoproducts with an aldehyde group formed in methanol were confirmed by the reduction of sodium 3,5-dinitrosalicylate in the Lindsay's method. E. crus-galli war. oryzicola was not controlled by the quinclorac residues photodegraded at tile concentrations higher than 30 ppm of the photosensitizer PS-3 in a flooded rice paddy soil. These results indicate that the quinclorac residues in aqueous solution and soil can be degraded efficiently by tile photosensitizers PS-1, PS-3, and PS-6.