Photochemistry Research Papers - Academia.edu (original) (raw)

Abstract— Irradiation of 1,3–dimethyluracil (DMU) in 1–aminopropane (AP) with u.v. light resulted in the formation of reduced and dimeric forms of DMU and adducts between DMU and AP. The formation of these compounds may be rationalized... more

Abstract— Irradiation of 1,3–dimethyluracil (DMU) in 1–aminopropane (AP) with u.v. light resulted in the formation of reduced and dimeric forms of DMU and adducts between DMU and AP. The formation of these compounds may be rationalized from the activation of either DMU or AP. Irradiation of DMU and poly-l-lysine in water with u.v. light resulted in the extensive binding of DMU to poly-l-lysine. The pyrimidine is probably attached to the ε-carbon of the polypeptide at the 6–position. The biological implications of these studies are discussed.

The photochemical behavior of oxyfluorfen [2-chloro-1-(3-etoxy-4-nitrophenoxy)-4-(trifluoromethyl) benzene] on two Greek soils was investigated. Soils were sampled from Nea Malgara and Preveza regions, characterized by a different organic... more

The photochemical behavior of oxyfluorfen [2-chloro-1-(3-etoxy-4-nitrophenoxy)-4-(trifluoromethyl) benzene] on two Greek soils was investigated. Soils were sampled from Nea Malgara and Preveza regions, characterized by a different organic matter content. Soils were spiked with the diphenyl-ether herbicide and irradiation experiments were performed either in the laboratory with a solar simulator (xenon lamp) or outside, under natural sunlight irradiation; other soil samples were kept in the dark to control the retention reaction. Kinetic parameters of both retention and photochemical reactions were calculated using zero-, first- and second- (Langmuir-Hinshelwood) order equations, and best fit was checked through statistical analysis. The soil behaviors were qualitatively similar but quantitatively different, with the soil sampled from the Nea Malgara region much more sorbent as compared with Preveza soil. All studied reactions followed second-order kinetics and photochemical reaction...

Iron overload in human body causes damages to our internal organs and can be fatal if untreated. To make aware of this ill effect to the public living nearby an Iron Workshop in residential area of Ernakulam District in Kerala, a study on... more

Iron overload in human body causes damages to our internal organs and can be fatal if untreated. To make aware of this ill effect to the public living nearby an Iron Workshop in residential area of Ernakulam District in Kerala, a study on the iron concentrations in soil samples collected within a distance of 200 meters around a Iron Workshop was done. It was found that the iron content as Fe (II) was higher than that of the normal value expected within in this area. During the raining season, this excess iron may leach out into the nearby wells. People drinking this well water may have a chance of getting iron overload. Based on our studies we have given awareness to the public regarding the symptoms of iron overload and precautions to be taken.

The fate of electronically excited states in DNA base stacks is of tremendous importance for subsequent photochemical damage reactions in the genome. In this study we present a femtosecond broadband pump-probe study on the adenine isomer... more

The fate of electronically excited states in DNA base stacks is of tremendous importance for subsequent photochemical damage reactions in the genome. In this study we present a femtosecond broadband pump-probe study on the adenine isomer 2-aminopurine (Ap) incorporated into trinucleotides. After selective excitation of Ap we can monitor energy delocalization between neighboring Ap moieties as well as excited state electron transfer, depending on the sequence of the trinucleotide. Our results establish the time scale for intrastand excimer formation and reveal the lifetime of the excimer state.

An increase in random molecular vibrations of a solid owing to heating above the melting point leads to a decrease in its long-range order and a loss of structural symmetry. Therefore conventional liquids are isotropic media. Here we... more

An increase in random molecular vibrations of a solid owing to heating above the melting point leads to a decrease in its long-range order and a loss of structural symmetry. Therefore conventional liquids are isotropic media. Here we report on a light-induced isothermal transition of a polymer film from an isotropic solid to an anisotropic liquid state in which the

A method was developed for the determination of aflatoxin B1 in medical herbs (senna pods, botanical name Cassia angustifolia; devil's claw, botanical name Harpagophytum procumbens; and ginger roots, botanical name Zingiber... more

A method was developed for the determination of aflatoxin B1 in medical herbs (senna pods, botanical name Cassia angustifolia; devil's claw, botanical name Harpagophytum procumbens; and ginger roots, botanical name Zingiber officinale). The method, which was tested in a mini-collaborative study by 4 laboratories, is based on an immunoaffinity cleanup followed by reversed-phase high-performance liquid chromatography separation and fluorescence detection after post-column derivatization. It allows the quantitation of aflatoxin B1 at levels lower than 2 ng/g. A second extractant (acetone-water) was tested and compared to the proposed methanol-water extractant. Several post-column derivatization options (electrochemically generated bromine, photochemical reaction, and chemical bromination) as well as different integration modes (height versus area) were also investigated. No differences were found depending on the choice of derivatization system or the signal integration mode used. ...

Radiographers process X-ray films using developer and fixer solutions that contain chemicals known to cause or exacerbate asthma. In a study in British Columbia, Canada, radiographers' personal exposures to glutaraldehyde (a... more

Radiographers process X-ray films using developer and fixer solutions that contain chemicals known to cause or exacerbate asthma. In a study in British Columbia, Canada, radiographers' personal exposures to glutaraldehyde (a constituent of the developer chemistry), acetic acid (a constituent of the fixer chemistry), and sulfur dioxide (a byproduct of sulfites, present in both developer and fixer solutions) were measured. Average full-shift exposures to glutaraldehyde, acetic acid, and sulfur dioxide were 0.0009 mg/m3, 0.09 mg/m3, and 0.08 mg/m3, respectively, all more than one order of magnitude lower than current occupational exposure limits. Local exhaust ventilation of the processing machines and use of silver recovery units lowered exposures, whereas the number of films processed per machine and the time spent near the machines increased exposures. Personnel in clinic facilities had higher exposures than those in hospitals. Private clinics were less likely to have local exha...