Monochromatic Ultraviolet Irradiation Research Articles

Effects of UV254 irradiation on residual chlorine and DBPs in chlorination of model organic-N precursors in swimming pools

Ultraviolet (UV) irradiation is commonly applied as a secondary disinfection process in chlorinated pools. UV-based systems have been reported to yield improvements in swimming pool water and air chemistry, but to date these observations have been largely anecdotal. The objectives of this investigation were to evaluate the effects of UV irradiation on chlorination of important organic-N precursors in swimming pools.Creatinine, L-arginine, L-histidine, glycine, and urea, which comprise the majority of the organic-N in human sweat and urine, were selected as precursors for use in conducting batch experiments to examine the time-course behavior of several DBPs and residual chlorine, with and without UV254 irradiation. In addition, water samples from two natatoria were subjected to monochromatic UV irradiation at wavelengths of 222 nm and 254 nm to evaluate changes of liquid-phase chemistry. UV254 irradiation promoted formation and/or decay of several chlorinated N-DBPs and also increased the rate of free chlorine consumption. UV exposure resulted in loss of inorganic chloramines (e.g., NCl3) from solution. Dichloromethylamine (CH3NCl2) formation from creatinine was promoted by UV exposure, when free chlorine was present in solution; however, when free chlorine was depleted, CH3NCl2 photodecay was observed. Dichoroacetonitrile (CNCHCl2) formation (from L-histidine and L-arginine) was promoted by UV254 irradiation, as long as free chlorine was present in solution. Likewise, UV exposure was observed to amplify cyanogen chloride (CNCl) formation from chlorination of L-histidine, L-arginine, and glycine, up to the point of free chlorine depletion. The results from experiments involving UV irradiation of chlorinated swimming pool water were qualitatively consistent with the results of model experiments involving UV/chlorination of precursors in terms of the behavior of residual chlorine and DBPs measured in this study.The results indicate that UV254 irradiation promotes several reactions that are involved in the formation and/or destruction of chlorinated N-DBPs in pool settings. Enhancement of DBP formation was consistent with a mechanism whereby a rate-limiting step in DBP formation was promoted by UV exposure. Promotion of these reactions also resulted in increases of free chlorine consumption rates.

Tuning depth profiles of organosilicate films with ultraviolet curing

This study demonstrates that ultraviolet (UV) radiation curing can control depth profiles of organosilicate films. Striking differences between the effects of monochromatic and broadband UV irradiation were observed. For the same as-deposited organosilicate film and cure duration, monochromatic radiation has a greater impact on film structure, elastic modulus, and fracture resistance, but also results in a greater degree of depth dependent properties. Oscillating elastic modulus through the film thickness was observed with force modulation atomic force microscopy. We present a new standing wave model that accurately predicts the resulting depth dependent stiffness variations considering changes in film shrinkage and refractive index in terms of curing time, and can further be used to account for initial film thickness dependence of UV curing and film absorption. Promising applications of the depth dependent UV curing to produce multifunctional ultralow-k layers with a single postdeposition curing process are discussed.

Induction and inhibition of cyclobutane pyrimidine dimer photolyase in etiolated cucumber (Cucumis sativus) cotyledons after ultraviolet irradiation depends on wavelength

Under polychromatic ultraviolet (UV) irradiation (maximum energy at 327 nm) the activity of DNA photolyase specific to cyclobutane pyrimidine dimers (CPDs), CPD photolyase, increased by an amount which depended on UV irradiance, and the level of CPD photolyase gene (CsPHR) transcripts temporarily increased before the activity reached a constant level. UV light (>320 nm) was more effective than visible light at increasing CPD photolyase activity. In contrast, monochromatic UV irradiation at wavelengths <300 nm increased the level of CsPHR transcripts similarly to irradiation at wavelengths >320 nm, but reduced CPD photolyase activity compared with the dark control. Exposure of a CPD photolyase solution to UV-C (254 nm) reduced enzyme activity and induced accumulation of H(2)O(2). Addition of H(2)O(2) to the enzyme solution also inactivated CPD photolyase activity. These results suggest the possibility that reactive oxygen species participate in the inactivation of CPD photolyase in cotyledons exposed to UV irradiation of <300 nm.

Effect of ultraviolet irradiation on the protein synthesis of human skin cells: a study with a monochromatic ultraviolet irradiation apparatus.

Human beings always suffer from serious risk of exposure to ultraviolet (UV) rays in general as well as in work environments but the health effects of UV are not yet fully understood. To enable fine analysis of the biological effects of UV at any given wavelength, we developed an apparatus that can experimentally irradiate cultured mammalian cells with monochromatic UV rays at any given wavelength. With this device, the effects of UV at 260, 280, 300 and 320 nm on the total protein synthesis of human skin-derived NB1RGB cells were examined. An inhibitory effect of UV at 260 and 280 nm was evident, whereas UV at 300 and 320 nm had only a marginal effect. UV at 280 nm also decreased amino acid uptake, which appears, at least partly, to be responsible for reduced protein synthesis. Metallothioneins (MTs), known as proteins defending against heavy metal toxicity, have been reported to be induced after UV irradiation, but UV at 280 nm did not induce MTs in NB1RGB cells. Cadmium pretreatment of cells, that had been assumed to protect cells from UV damage via MT induction, did not increase cell viability after exposure to UV at 280 nm. The present study unambiguously revealed the biological effects of monochromatic UV rays, also showing that the UV-irradiating apparatus can be a powerful tool for studying the health effects of UV.

紙の劣化とその対策 第ＩＩ報 機械パルプ含有紙の老化

Degradation of book papers has been compared to a slow fire since decades and some conservation studies such as neutralization by diethyl zinc have been investigated. This paper deals with differentiation of papers from mechanical and chemical pulps by various accelerated aging tests.Papers containing mechanical pulp, such as so-called semi-woodfree, wood containing, printing paper grade D and newsprint, showed no greater degradation rates in folding endurance and brightness at 105°C dry, 80°C -65%RH moist and repetition of 30% to 80%RH at 80°C recycling in 2 hrs interval accelerated agings compared with acidic and neutral woodfree papers.When thermomechaniacal pulp was partially delignified with chlorine dioxide solution, handsheets from the pulps showed greater degradation rates with lower lignin contents.According to color reversion tests under direct sun light, sun light through glass plate and fluorescence light, papers containing mechanical pulp exhibited significantly faster color reversion than in high temperature accelerated aging tests. The maximum color reversion at around 340 nm was observed by a monochromatic ultra-violet irradiation, however, no deterioration effect on folding endurance was observed at the above mentioned wave length.

Xeroderma pigmentosum complementation group F in a non-Japanese patient

Genetic complementation studies allowed assignment of a 22-year-old-white woman to the rare complementation group of classic, excision-defective xeroderma pigmentosum (group F cell strain), previously reported only in patients from Japan. She manifested mild cutaneous changes, with no tumors and normal sensitivity to monochromatic ultraviolet irradiation. Unscheduled deoxyribonucleic acid synthesis in cultured fibroblasts (XP126LO) after irradiation with germicidal ultraviolet light was reduced to 13% of control values during the first 2 hours and rose to 45% of normal by 7 to 8 hours.

Study of the interaction between yeast tRNA Phe and yeast phenylalanyl-tRNA synthetase by monochromatic ultraviolet irradiation at various wavelengths Advantages and limits of the method

The interactions between yeast tRNA Phe and phenylalanyl-tRNA synthetase were studied by analysis of the covalent adducts obtained upon monochromatic ultraviolet irradiation at different wavelengths (248, 282, 292, 302 and 313 nm). The high extent of inactivation of phenylalanyl-tRNA synthetase, together with the partial modification of tRNA, as well as the peculiar instability of most of the covalent bonds formed upon irradiation constitute severe limitations to the use of the technique and to the interpretation of the results. These disadvantages led us to select an irradiation wavelength of 248 nm and to use only mild isolation procedures allowing a good recovery of the covalent adducts formed. Seven major tryptic peptides of the enzyme were found to be cross-linked to tRNA Phe whereas six major T 1-oligonucleotides were covalently linked to the protein, among these, the three cross-linked oligonucleotides previously described by Shoemaker and Schimmel (J. Biol. Chem. 250 (1975) 4440–4444) in the same system. The difference in the number of covalently linked oligonucleotides is discussed in the light of the instability of the covalent linkages. The localization of the six oligonucleotides at the inside of the two branches forming the L-shaped tRNA molecule is similar to that observed in the yeast valine system (Renaud et al., Eur. J. Biochem. 101 (1979) 475–483) and is consistent with the interaction model previously described (Rich and Schimmel, Nucl. Acids Res. 4 (1977) 1649–1665 and Ebel et al. in Transfer RNA: structure, properties and recognition, (1979) pp. 325–343 Cold Spring Harbor Laboratory, NY). The occurrence of covalent cross-linking upon irradiation in the tryptophan absorption band (302 nm) strongly suggests the participation of this residue in the stabilization of the tRNA enzyme complex.

Virulence of Heliothis nuclear polyhedrosis virus exposed to monochromatic ultraviolet irradiation

Suspensions of polyhedra of the Heliothis nuclear polyhedrosis virus were irradiated at 16 microwatts/cm 2 with narrow-band ultraviolet energy at wavelengths of 257 nanometer (nm) (1 nm = 1 × 10 −9 meter = 1 millimicron = 10 Ångstrom units), 307.5 nm, and 364 nm and with broad-band energy in the visible and near-infrared range and assayed for virulence with 20-mg larval bollworms, Heliothis zea, and tobacco budworms, Heliothis virescens. Wavelengths of 257 nm and 307.5 nm significantly inactivated virus, and 364 nm and the visible range may have inactivated it. Mortality was reduced 45 and 88.9% in bollworm and tobacco budworm, respectively, when they were assayed with a polyhedral suspension (1250 viral inclusions/mm 2 of diet surface) treated with monochromatic energy at 307.5 nm.

Production of lethal mutations in the fungus Chætomium globosum by monochromatic ultra-violet irradiation

Production of lethal mutations in the fungus Chaetomium globosum by monochromatic ultra-violet irradiation

Lethal and Quasi-Lethal Effects Produce by Monochromatic Ultra-Violet Irradiation

ABSTRACT Lethal and quasi-lethal effects produced by monochromatic ultra-violet irradiation of biological material representing the phyla Bacteria, Fungi, Angiospermae, Protozoa and Arthropoda have been observed and recorded over a range of wavelengths from 254 to 365 mµ. Although the materials represent high and low forms in both vegetable and animal kingdoms, there is a striking similarity in their behaviour. There is a sudden increase in the lethal effect between 313 and 297 mµ in every case. Although the curves connecting lethal dose with wave-length are closely similar in all cases, the absolute magnitudes of doses are widely different. The ratio of lethal doses for different material may be as high as two hundred to one at corresponding wave-lengths. The ratio of the greatest to the least dose recorded is of the order of a million to one. Tables and curves are given recording lethal and quasi-lethal doses for the different materials at different wave-lengths, and brief accounts of the conditions in which the experiments were conducted are given in the text. An interesting correlation is exhibited between the form of the lethal dose curves and the ultra-violet radiation in daylight.

Production of saltants of Chaetomium globosum by monochromatic ultra-violet irradiation

Production of saltants of Chaetomium globosum by monochromatic ultra-violet irradiation