Photoreactivation of RNA in UV-irradiated insect eggs (Smittia SP., Chironomidae, Diptera)

International Nuclear Information System (INIS)

Jaeckle, H.; Kalthoff, K.

1978-01-01

Irradiation of Smittia eggs with UV during intravitelline cleavage causes the formation of pyrimidine dimers in the (largely ribosomal) RNA of the eggs. The yield of dimers is wavelength-dependent in a way that strongly suggests the involvement of photosensitizing egg components. Illumination of UV-irradiated eggs with light (380 or 400 nm) causes both photoreactivation of the eggs and monomerization of the pyrimidine dimers in their RNA. The photoreactivable sector of the biological damage is correlated with the amount of pyrimidine dimers present in the RNA after inactivation of the eggs with UV of different wavelengths. The data are regarded as the first direct evidence that the photoreactivation of a eukaryotic organism is correlated with the light-dependent (and apparently enzymatic) monomerization of pyrimidine dimers in RNA. (author)

Redistribution of melanosomal complexes within keratinocytes following UV-A irradiation

International Nuclear Information System (INIS)

Lavker, R.M.; Kaidbey, K.H.

1982-01-01

In contrast to other ultraviolet (UV) wavelengths, UV-A can induce long-term or 'true' pigmentation rapidly with little or no latency. The response cannot be clearly separated from immediate pigment darkening and is too rapid in onset to be explained by neomelanogenesis. In order to investigate possible mechanisms for this phenomenon, UV-irradiated skin was examined microscopically and ultrastructurally 18 h postirradiation. Specimens from skin sites tanned by exposure to melanogenic doses of UV-A showed a paradoxical reduction in the degree of basal melanization by light microscopy compared to unirradiated skin. Ultrastructurally, there was migration and dispersion of packaged melanosomes within keratinocytes from their normal, aggregated location around the nucleus towards the periphery of the cell. These changes were not observed in specimens exposed to melanogenic doses of UV-B. We propose that UV-A wavelengths can selectively cause redistribution of melanin-laden organelles within human keratinocytes in vivo and that this phenomenon accounts for the visually observed hyperpigmentation that develops soon after single exposures to these wavelengths. Dispersion of melanosomal complexes may be another mechanism by which UV-radiation (UVR) can induce tanning in human skin. (orig.)

Redistribution of melanosomal complexes within keratinocytes following UV-A irradiation

Energy Technology Data Exchange (ETDEWEB)

Lavker, R.M.; Kaidbey, K.H.

1982-03-01

In contrast to other ultraviolet (UV) wavelengths, UV-A can induce long-term or 'true' pigmentation rapidly with little or no latency. The response cannot be clearly separated from immediate pigment darkening and is too rapid in onset to be explained by neomelanogenesis. In order to investigate possible mechanisms for this phenomenon, UV-irradiated skin was examined microscopically and ultrastructurally 18 h postirradiation. Specimens from skin sites tanned by exposure to melanogenic doses of UV-A showed a paradoxical reduction in the degree of basal melanization by light microscopy compared to unirradiated skin. Ultrastructurally, there was migration and dispersion of packaged melanosomes within keratinocytes from their normal, aggregated location around the nucleus towards the periphery of the cell. These changes were not observed in specimens exposed to melanogenic doses of UV-B. We propose that UV-A wavelengths can selectively cause redistribution of melanin-laden organelles within human keratinocytes in vivo and that this phenomenon accounts for the visually observed hyperpigmentation that develops soon after single exposures to these wavelengths. Dispersion of melanosomal complexes may be another mechanism by which UV-radiation (UVR) can induce tanning in human skin.

Influence of UV-Irradiation on Latent Tracks in Polyethylene Terephthalate Films

International Nuclear Information System (INIS)

Wen Qi; Wang Peng-Fei; Ling Yun; Wang Mao; Yan Dong-Xiao; Wang Yu-Gang; Cao Xing-Zhong; Wang Bao-Yi

2016-01-01

Polyethylene terephthalate (PET) films in thickness of 12 μm are irradiated by Xe and Au ions at the energies of 9.5 and 11.4MeV/u and with the ion fluence from 5 × 10"9 cm"−"2 to 1 × 10"1"1 cm"−"2. After irradiation, ultra-violet lights are used to illuminate the samples with latent tracks at the wavelength of 365 nm with flux density of 4.2 mW/cm"−"2. UV-irradiation effects on tracked PET are investigated by the UV-vis spectrum and positron annihilation lifetime spectroscopy (PALS). It is found that carbonaceous clusters in PET films are generated by ion irradiation and decomposed with UV illumination by calculating the optical energy band gap E_g in the UV-vis spectrum. The free volumes behave differently in track and bulk after UV illumination. In our experiment, the PALS results show an increase in radius and density of free volume in tracked PET films after UV treatment, which indicates an expansion in radius of latent tracks. (paper)

Plant responses to UV-B irradiation are modified by UV-A irradiation

International Nuclear Information System (INIS)

Middleton, E.M.; Teramura, A.H.

1993-01-01

The increasing UV-B radiation (0.28-0.32 μm) reaching the earth's surface is an important concern. Plant response in artificial UV-B irradiation studies has been difficult to assess, especially regarding photosynthetic pigments, because the fluorescent lamps also produce UV-A (0.32-0.40μm) radiation which is involved with blue light in pigment synthesis. Both UV-A and UV-B irradiances were controlled in two glasshouse experiments conducted under relatively high PPFD (> 1300μmol m -2 s -1 ) at two biologically effective daily UV-B irradiances (10.7 and 14.1 kJ m -2 ); UV-A irradiances were matched in Controls (∼5, 9 kJ m -2 ). Normal, chlorophyll-deficient, and flavonoid-deficient isolines of soybean cultivar, Clark, were utilized. Many growth/ pigment variables exhibited a statistically significant interaction between light quality and quantity: in general, UV-A radiation moderated the damaging effects of UV-B radiation. Regression analyses demonstrated that a single negative function related photosynthetic efficiency to carotenoid Content (r 2 =0.73, P≤0.001), implying a open-quotes costclose quotes in maintaining carotenoids for photoprotection. A stomatal limitation to photosynthesis was verified and carotenoid content was correlated with UV-B absorbing compound levels, in UV-B irradiated plants

Retrieval of Surface Ozone from UV-MFRSR Irradiances using Deep Learning

Science.gov (United States)

Chen, M.; Sun, Z.; Davis, J.; Zempila, M.; Liu, C.; Gao, W.

2017-12-01

High concentration of surface ozone is harmful to humans and plants. USDA UV-B Monitoring and Research Program (UVMRP) uses Ultraviolet (UV) version of Multi-Filter Rotating Shadowband Radiometer (UV-MFRSR) to measure direct, diffuse, and total irradiances every three minutes at seven UV channels (i.e. 300, 305, 311, 317, 325, 332, and 368 nm channels with 2 nm full width at half maximum). Based on the wavelength dependency of aerosol optical depths, there have been plenty of literatures exploring retrieval methods of total column ozone from UV-MFRSR measurements. However, few has explored the retrieval of surface ozone. The total column ozone is the integral of the multiplication of ozone concentration (varying by height and time) and cross section (varying by wavelength and temperature) over height. Because of the distinctive values of ozone cross section in the UV region, the irradiances at seven UV channels have the potential to resolve the ozone concentration at multiple vertical layers. If the UV irradiances at multiple time points are considered together, the uncertainty or the vertical resolution of ozone concentrations can be further improved. In this study, the surface ozone amounts at the UVMRP station located at Billings, Oklahoma are estimated from the adjacent (i.e. within 200 miles) US Environmental Protection Agency (EPA) surface ozone observations using the spatial analysis technique. Then, the (direct normal) irradiances of UVMRP at one or more time points as inputs and the corresponding estimated surface ozone from EPA as outputs are fed into a pre-trained (dense) deep neural network (DNN) to explore the hidden non-linear relationship between them. This process could improve our understanding of their physical/mathematical relationship. Finally, the optimized DNN is tested with the preserved 5% of the dataset, which are not used during training, to verify the relationship.

Reactivation of UV- and γ-irradiated herpes virus in UV- and X-irradiated CV-1 cells

International Nuclear Information System (INIS)

Takimoto, K.; Niwa, O.; Sugahara, T.

1982-01-01

Enhanced reactivation of UV- and γ-irradiated herpes virus was investigated by the plaque assay on CV-1 monkey kidney monolayer cells irradiated with UV light or X-rays. Both UV- and X-irradiated CV-1 cells showed enhancement of survival of UV-irradiated virus, while little or no enhancement was detected for γ-irradiated virus assayed on UV- or X-irradiated cells. The enhanced reactivation of UV-irradiated virus was greater when virus infection was delayed 24 or 48 h, than for infection immediately following the irradiation of cells. Thus the UV- or X-irradiated CV-1 cells are able to enhance the repair of UV damaged herpes virus DNA, but not of γ-ray damaged ones. (author)

Far UV irradiation of DNA in the presence of proteins, amino acids or peptides

International Nuclear Information System (INIS)

Larcom, L.L.; Rains, C.A.

1985-01-01

The DNA of bacteriophage SPO2c12 was subjected to 254 nm irradiation in solutions containing lysozyme or histone. The sensitivity of phage DNA to biological inactivation by UV increased as the amount of lysozyme bound per DNA strand increased. Although binding constants could not be measured for the DNA-histone interaction, this protein had a protective effect which was greater under conditions which cause enhanced binding. No crosslinking of either protein could be detected. Irradiation was also performed in the presence of various amino acids and short peptides. These were chosen to include amino acids which: (1) are positively charged, (2) absorb UV of this wavelength or (3) form UV-induced crosslinks to DNA. None of the amino acids tested affected sensitivity of the DNA to biological inactivation. Peptides containing a UV-absorbing amino acid and a positively charged amino acid enhanced sensitivity. For each of these peptides, a mixture of the constituent amino acids had the same effect as the peptide itself. Under the conditions used, no evidence for formation of DNA-amino acid crosslinks was found. The results indicate that proteins and peptides can sensitize DNA to UV inactivation by mechanisms other than covalent crosslink formation. (author)

The competitive action of UV of different wavelengths of the survival of Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Ivanova, Eh.V.; Pospelov, M.E.; Strakhovskaya, M.G.; Frajkin, G.Ya.

1982-01-01

During investigation into combined action of different wavelengths of UV spectrum on Saccharomyces cerevisiae yeast (strains XII and CI-9) it was established that 334 nm preliminary irradiation causes photoprotection of cells from lethal action of 254 and 313 nm UV-rays. During 334 postradiation irradiation strengthening of lethal action of 254 and 313 nm UV-rays for strain XII, not capable of photoreactivation, is observed. Using specific inhibitor of serotonin-biosynthesis- parachlorophenyl alanine it is shown that 334 nm serotonin synthesis induced by light lies in the base of mechanism of both effects. The effect of postradiation action of 334 nm light for strain CI-9, capable of photoreactivation, depends on interaction of two different photobiological reactions caused by light, photoreactivation and photoinduced synthesis of serotonin

Effect of UV irradiation on the apoptosis and necrosis of Jurkat cells using UV LEDs

Science.gov (United States)

Inada, Shunko A.; Amano, Hiroshi; Akasaki, Isamu; Morita, Akimichi; Kobayashi, Keiko

2009-02-01

Phototherapy is a very effective method for treating most of the incurable skin diseases. A fluorescent light bulb is used as a conventional UV light source for this type of therapy. However, infrared radiation from the light source sometimes causes serious problems on patient's health. In addition, the normal part of the skin is irradiated when a large fluorescent light bulb is used. Moreover, a conventional UV irradiation system is heavy and has a short lifetime and a high electrical power consumption. Therefore, a new UV light source for solving the problems of phototherapy is required. To realize low-power-consumption, lightweight and long-lifetime systems, group III nitride-based UV-A1 light-emitting diodes (LEDs) were investigated. We examined the UV LED irradiation of Jurkat cell, which is a tumor cell and more sensitive to UV light than a healthy cell. The numbers of apoptotic and necrotic cells were confirmed to be the same using a UV LED and a conventional lamp system. The UV LED showed the possibility of realizing a new UV light source for phototherapy.

The inhibition of repair in UV irradiated human cells

International Nuclear Information System (INIS)

Collins, A.R.S.; Schor, S.L.; Johnson, R.T.

1977-01-01

Three different assay procedures are used to determine the effects of hydroxyurea on excision repair in UV-irradiated HeLa cells. At the cytological level, incubation of UV-irradiated metaphase cells with hydroxyurea caused chromosome decondensation. Using a modified alkaline sucrose gradient sedimentation technique involving minimal lysis before centrifugation, a marked retardation was found in the sedimentation of DNA from UV-irradiated cells incubated for a short period with hydroxyurea. The effect of hydroxyurea on the incorporation of [ 3 H]thymidine by UV-irradiated G1 cells was found to depend on the concentration of thymidine present in the medium. The results point to an inhibition of repair DNA synthesis by hydroxyurea (or deoxyadenosine), at the level of the supply of DNA precursors, i.e. in the same way that these agents inhibit semiconservative DNA synthesis. In the presence of these inhibitors, single-strand gaps accumulate in the DNA

The cloud effects on UV irradiance modeled in Antarctica

International Nuclear Information System (INIS)

Rafanelli, C.; Anav, A.; Ciattaglia, L.; Di Menno, I.; Di Menno, M.; Araujo, J.; Ochoa, H.; Rodriguez, H.

2004-01-01

Full text: The measurement of solar UV radiation in Antarctica is very important in order to obtain information about Ozone level, and many spectro radiometers are installed in the area to perform this task. Usually, their use is very difficult in harsh environment like Southern polar regions, and several multichannel radiometers have been installed. The evaluation of the irradiance and total ozone levels are done using analytical models. A new semi-analytical method to estimate the solar UV irradiance at ground, named WL4UV, was developed. Using spectral irradiance values at 4 selected wavelengths in the UV-B and UV-A regions (305, 320, 340 and 380 nm), the solar UV irradiance at ground is evaluated with low percent of error. The applicability of the method has been tested for clear sky but such conditions are not common in Antarctic. This work investigate the applicability of the WL4UV model under cloudy sky conditions. The 4 irradiance necessary for the model were selected from spectrophotometer Brewer measurements carried out in the Argentinean Belgrano II base (77 degrees 52' S and 34 degrees 38' W). Other tests using spectrophotometers, Brewer and SUV 100, located in Ushuaia, (54 degrees 50' S and 68 degrees 19' W), were also too. This project was funded by the PNRA, IIA-DNA and CADIC for funding and supporting the activities. They thank also all the Brewer operators that in these years spent their time in the management of the instrument. Last but not the least they thank all IIA-DNA personnel for the professional help they put in carrying out the activities in all these years. (author)

Risks of increased UV-B radiation for humans

International Nuclear Information System (INIS)

Przybilla, B.; Eberlein-Koenig, B.; Bergner, T.

1994-01-01

If not compensated in any way, depletion of the stratospheric ozone layer leads to an increase of UV-B radiation at the earth's surface, especially towards the short-wave range, which is biologically the more active. The most concerning effect here is that of UV-B induced skin reactions, in particular malignant skintumors (malignant melanoma, spinocellular carcinoma, basalioma), whose incidence is expected to increase in future. As some photoreactions can be inhibited or enhanced also by radiation outside their action spectrum, it is possible for changes in solar spectral radiation flux density to influence photo-induced reactions that are driven at wavelengths outside the UV-B range. The authors have performed studies for developing methods of quantifying individual UV sensitivity. In vitro studies have shown that UV-A dependent photoreactions can be partly inhibited by UV-B. A number of drugs, as well as sulphites, which are used as preservatives amongst other things, have been shown to have phototoxic properties that may be relevant to photocarcinogenesis. Irradiation tests on cell cultures for different UV-B ranges have shown that irradiation at shorter wavelengths leads to a stronger release of proinflammatory cytokines that ar longer wavelengths with the same dose. Altogether it can be said that despite compelling theoretical evidence it is not easily possible to predict the actual consequences of an increase in particular of short-wave UV-B radiation at the earth's surface. The assumed effects must be examined individually by appropriate methods. (orig.) [de

The Effects of Short Wave UV Irradiation (254-366nm on Color Values of Recycled and Bleached ONP/OMP Pulps

Directory of Open Access Journals (Sweden)

Emrah Peşman

2011-04-01

Full Text Available ABSTRACT As it is known, mechanical pulp papers include significant amount of lignin and carbohydrates as well as cellulose. Thus, when these lignin reach papers irradiated with short wave UV light they could not protect their color. In this study, bleaching of ONP/OMG recycled pulps with hydrogen peroxide, sodium percarbonate, sodium dithyonite, sodium borohydride and formamidin sulfunic acid were performed. Then the test papers of these pulps were irradiated with 254-366nm UV light and changes in the ISO Brightness, CIE L*a*b*, yellowness (YI and whiteness (WI values were observed. At the result of study, all bleaching agents were determined as insufficient in the respect of color stability. But if they compared with each other, the two stages sodium percarbonate-sodium borohydride bleaching sequence was gave the best results against to color reversion. Keywords: Old news/old magazine papers (ONP/OMG, Bleaching, Color Stability, UV Irradiation

A UV pre-ionized dual-wavelength short-pulse high-power CO{sub 2} laser facility for laser particle acceleration research

Energy Technology Data Exchange (ETDEWEB)

Ebrahim, N A; Mouris, J F; Davis, R W

1994-12-01

In this report we describe the Chalk River dual-wavelength, short-pulse, single-mode, high-power CO{sub 2} laser facility for research in laser particle acceleration and CANDU materials modifications. The facility is designed and built around UV-preionized transversely-excited atmospheric-pressure (TEA) Lumonics CO{sub 2} laser discharge modules. Peak focussed power densities of up to 2 x 10{sup 14} W/cm{sup 2} in 500 ps pulses have been obtained. (author). 10 refs., 9 figs.

Effect of UV irradiation on optical, mechanical and microstructural properties of PVA/NaAlg blends

Science.gov (United States)

Sheela, T.; Bhajantri, R. F.; Ravindrachary, V.; Rathod, Sunil G.; Pujari, P. K.; Poojary, Boja; Somashekar, R.

2014-10-01

Poly(vinyl alcohol) (PVA)/Sodium alginate (NaAlg) blend films with 60:40 wt% were prepared by solution casting method and subjected to UV irradiation for different intervals of time. The optical, mechanical and morphological properties of the blend films were modified after UV irradiation. The FTIR and FT-Raman results show the chemical interaction between PVA and NaAlg. The UV-vis absorption peak at 278 nm shifts slightly towards longer wavelength and the absorption increases with irradiation time, indicate the increase in crosslinking network. The XRD results show an increase in amorphous nature with increase in UV irradiation time. The DSC/TGA results show a single glass transition temperature (Tg), which confirm that the blends are completely miscible and thermally stable up to 250 °C. The Young's modulus, tensile strength and stiffness of the blend films increase with increase in UV irradiation time. The SEM images confirm that the surface of 48 h UV irradiated PVA:NaAlg blend is more photo-resistant than unirradiated blend.

Action spectra for the depression of photosynthesis by UV irradiation in Lactuca sativa L. and Rumex alpinus L

International Nuclear Information System (INIS)

Bogenrieder, A.

1982-01-01

In previous investigations it was shown that effects of UV on photosynthesis, growth and development of higher plants are mainly inhibitory, although over a long period stimulation may also be seen. These short term effects can often, depending on wavelength and fluence rate, to be found after only a few minutes. Further investigations showed that even by the highest available UB fluence rates, a linear relationship between total fluence and depression of photosynthesis occurred, at least for an irradiation period of 6 hours (Bogenrieder and Klein 1982). An action spectrum for this relatively short term effect is presented. (orig./AJ)

Direct comparison between the angular distributions of the erythemal and eye-damaging UV irradiances: a pilot study.

Science.gov (United States)

Schouten, P; Parisi, A V

2011-02-07

Several broadband ultraviolet (UV) radiation angular distribution investigations have been previously presented. As the biologically damaging effectiveness of UV radiation is known to be wavelength dependent, it is necessary to expand this research into the distribution of the spectral UV. UV radiation is also susceptible to Rayleigh and Mie scattering processes, both of which are completely wavelength dependent. Additionally, the majority of previous measurements detailing the biologically damaging effect of spectral UV radiation have been oriented with respect to the horizontal plane or in a plane directed towards the sun (sun-normal), with the irradiance weighted against action spectra formulated specifically for human skin and tissue. However, the human body consists of very few horizontal or sun-normal surfaces. Extending the previous research by measuring the distribution of the spectral irradiance across the sky for the complete terrestrial solar UV waveband and weighting it against erythemal, photoconjunctivital and photokeratital action spectra allowed for the analysis of the differences between the biologically effective irradiance (UV(BE)) values intercepted at different orientations and the effect of scattering processes upon the homogeneity of these UV(BE) distributions. It was established that under the local atmospheric environment, the distribution profile of the UV(BE) for each biological response was anisotropic, with the highest intensities generally intercepted at inclination angles situated between the horizontal and vertical planes along orientations closely coinciding with the sun-normal. A finding from this was that the angular distributions of the erythemal UV(BE) and the photoconjunctivital UV(BE) were different, due to the differential scattering between the shorter and longer UV wavelengths within the atmosphere. Copyright © 2010 Elsevier B.V. All rights reserved.

Quality assessment of solar UV irradiance measured with array spectroradiometers

Science.gov (United States)

Egli, Luca; Gröbner, Julian; Hülsen, Gregor; Bachmann, Luciano; Blumthaler, Mario; Dubard, Jimmy; Khazova, Marina; Kift, Richard; Hoogendijk, Kees; Serrano, Antonio; Smedley, Andrew; Vilaplana, José-Manuel

2016-04-01

The reliable quantification of ultraviolet (UV) radiation at the earth's surface requires accurate measurements of spectral global solar UV irradiance in order to determine the UV exposure to human skin and to understand long-term trends in this parameter. Array spectroradiometers (ASRMs) are small, light, robust and cost-effective instruments, and are increasingly used for spectral irradiance measurements. Within the European EMRP ENV03 project "Solar UV", new devices, guidelines and characterization methods have been developed to improve solar UV measurements with ASRMs, and support to the end user community has been provided. In order to assess the quality of 14 end user ASRMs, a solar UV intercomparison was held on the measurement platform of the World Radiation Center (PMOD/WRC) in Davos, Switzerland, from 10 to 17 July 2014. The results of the blind intercomparison revealed that ASRMs, currently used for solar UV measurements, show a large variation in the quality of their solar UV measurements. Most of the instruments overestimate the erythema-weighted UV index - in particular at large solar zenith angles - due to stray light contribution in the UV-B range. The spectral analysis of global solar UV irradiance further supported the finding that the uncertainties in the UV-B range are very large due to stray light contribution in this wavelength range. In summary, the UV index may be detected by some commercially available ASRMs within 5 % compared to the world reference spectroradiometer, if well characterized and calibrated, but only for a limited range of solar zenith angles. Generally, the tested instruments are not yet suitable for solar UV measurements for the entire range between 290 and 400 nm under all atmospheric conditions.

Interrelations of UV-global/global/diffuse solar irradiance components and UV-global attenuation on air pollution episode days in Athens, Greece

International Nuclear Information System (INIS)

Koronakis, P.S.; Sfantos, G.K.

2002-01-01

An investigation of global ultraviolet (G UV ), global (G) and diffuse (G d ) solar intensities, continuously recorded over a period of five years at a station in Athens, Greece, and stored on the basis of hourly time intervals since 1996, has revealed the following: (a) UV-global irradiation, associated with the 290-395 nm wavelength region, constitutes 4.1% of global solar. (b) UV-global irradiance ranges from an average minimum of 2.4 W m -2 and 3.1% of global solar in January to an average maximum of 45 W m -2 and 7.8%, respectively, in June, both considered at 13:00, solar time. (c) There exists a good correlation among the two dimensionless irradiance ratios G UV /G d and G d /G in the form of an exponential relationship. (d) UV-global monthly irradiation data show evidence of temporal variability in Athens, from 1996 to 2000. (e) Anthropogenic and photochemical atmospheric pollutant agents (O 3 , CO, SO 2 , NO x , smoke) causing air pollution episodes seem to affect differently solar irradiance components. The main results of analysis (measurements within ± 2 h from solar noon) indicate that a buildup of O 3 and NO x inside the urban Athens plume during cloudless and windless warm days could cause: (i) UV-global irradiance depletion between 5.4% and 14.4%. (ii) Diffuse solar irradiance enhancement up to 38.1%. (iii) Global solar irradiance attenuation ranging up to 6.3%. (author)

Effects of UV-B irradiation on photomovement in the desmid, Cosmarium cucumis

International Nuclear Information System (INIS)

Haeder, D.-P.

1987-01-01

Monochromatic UV-B irradiation affects neither the absorption nor the fluorescence of the bulk pigments in the desmid Cosmarium cucumis but it impairs photomovement of these organisms at fluence rates which are not higher than the ambient level of solar UV-B irradiation. Photoaccumulations and phototaxis are strongly inhibited especially at wavelengths <= 300 nm while photodispersal at higher white light fluence rates is hardly affected by supplementary UV-B. This effect has important consequences for the growth and survival of populations in their natural environment: these photosynthetic organisms utilize photomovement to find and stay in areas of suitable visible light fluence rates. The UV-B component of solar irradiation both impairs the strategy of the organisms to find a suitable position and the escape mechanism by which the cells move out of areas with too strong white illuminances which photooxidize the bulk pigments and bleach the population within a few days. (author)

Delayed expression of enhanced reactivation and decreased mutagenesis of UV-irradiated adenovirus in UV-irradiated ataxia telangiectasia fibroblasts

International Nuclear Information System (INIS)

Bennett, C.B.; Rainbow, A.J.

1988-01-01

In this study the authors examined UV-enhanced reactivation (UVER) and UV-enhanced mutagenesis (UVEM) of UV-irradiated adenovirus in AT fibroblasts. UVER factors for Ad V antigen expression were significantly less than normal in AT strains tested when infection occurred immediately after UV-irradiation of cells. However, UVER factors were >1 and similar to those found for normal strains when cells were infected 24 h after UV-irradiation, indicating delay in the expression of UVER for Ad V antigen in AT cells. UV-irradiation of both normal and AT cells 24 h prior to infection also resulted in a significant increase in progeny survival for UV-irradiated Ad. In normal cells, this progeny UVER was concomitant with a significant increase in the mutation frequency for UV-irradiated virus (increase in targeted mutagenesis) suggesting existence of an inducible error-prone DNA repair mode in normal human cells. In contrast, pre-UV-irradiation of AT cells resulted in a significant decrease in the mutation frequency for UV-irradiated virus. (author)

Sexual dimorphism of short-wavelength photoreceptors in the small white butterfly, Pieris rapae crucivora

NARCIS (Netherlands)

Arikawa, K; Wakakuwa, M; Qiu, XD; Kurasawa, M; Stavenga, DG; Qiu, Xudong

2005-01-01

The eyes of the female small white butterfly, Pieris rapae crucivora, are furnished with three classes of short-wavelength photoreceptors, with sensitivity peaks in the ultraviolet (UV) (lambda(max) = 360 nm), violet (V) (lambda max = 425 nm), and blue (B) (lambda(max) = 453 nm) wavelength range.

Tritium-doping enhancement of polystyrene by ultraviolet laser and hydrogen plasma irradiation for laser fusion experiments

Energy Technology Data Exchange (ETDEWEB)

Iwasa, Yuki, E-mail: iwasa-y@ile.osaka-u.ac.jp [Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871 (Japan); Yamanoi, Kohei; Iwano, Keisuke; Empizo, Melvin John F.; Arikawa, Yasunobu; Fujioka, Shinsuke; Sarukura, Nobuhiko; Shiraga, Hiroyuki; Takagi, Masaru; Norimatsu, Takayoshi; Azechi, Hiroshi [Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871 (Japan); Noborio, Kazuyuki; Hara, Masanori; Matsuyama, Masao [Hydrogen Isotope Research Center, Organization for Promotion of Research, University of Toyama, 3190 Gofuku, Toyama 930-8555 (Japan)

2016-11-15

Highlights: • Tritium-doped polystyrene films are fabricated by the Wilzbach method with UV laser and hydrogen plasma irradiation. • The 266-nm laser-irradiated, 355-nm laser-irradiated, and hydrogen plasma-irradiated polystyrene films exhibit higher PSL intensities and specific radioactivities than the non-irradiated sample. • Tritium doping by UV laser irradiation can be largely affected by the laser wavelength because of polystyrene’s absorption. • Hydrogen plasma irradiation results to a more uniform doping concentration even at low partial pressure and short irradiation time. • UV laser and plasma irradiations can be utilized to fabricate tritium-doped polystyrene shell targets for future laser fusion experiments. - Abstract: We investigate the tritium-doping enhancement of polystyrene by ultraviolet (UV) laser and hydrogen plasma irradiation. Tritium-doped polystyrene films are fabricated by the Wilzbach method with UV laser and hydrogen plasma. The 266-nm laser-irradiated, 355-nm laser-irradiated, and hydrogen plasma-irradiated polystyrene films exhibit higher PSL intensities and specific radioactivities than the non-irradiated sample. Tritium doping by UV laser irradiation can be largely affected by the laser wavelength because of polystyrene’s absorption. In addition, UV laser irradiation is more localized and concentrated at the spot of laser irradiation, while hydrogen plasma irradiation results to a more uniform doping concentration even at low partial pressure and short irradiation time. Both UV laser and plasma irradiations can nevertheless be utilized to fabricate tritium-doped polystyrene targets for future laser fusion experiments. With a high doping rate and efficiency, a 1% tritium-doped polystyrene shell target having 7.6 × 10{sup 11} Bq g{sup −1} specific radioactivity can be obtained at a short period of time thereby decreasing tritium consumption and safety management costs.

Photoreactivation of cells and phages inactivated by UV of ecological wave-lengths

International Nuclear Information System (INIS)

Samojlova, K.A.; Yanovska, Eh.; Vizdalova, M.; Ceskoslovenska Akademie Ved, Brno. Biofysikalni Ustav)

1979-01-01

It has been found that the photoreactivity of infusoria Paramecium caudatum and bacteria Escherichia coli is high and practically similar if they are irradiated with short-wave (254 nm) and mean-wave (300-315 nm) UV radiation. The cells damaged with long-wave (315-400 nm) UV rays are not photoactivated. The latter is caused by the appearance of nonphotoreactivated damages since the phages jrradiated with the same UV rays are reactivated extremely weakly in the intact cells of bacteria (phage T7) or are not reactivated at all (phage lambdasub(c1 857))

Short wavelength FELS

International Nuclear Information System (INIS)

Sheffield, R.L.

1991-01-01

The generation of coherent ultraviolet and shorter wavelength light is presently limited to synchrotron sources. The recent progress in the development of brighter electron beams enables the use of much lower energy electron rf linacs to reach short-wavelengths than previously considered possible. This paper will summarize the present results obtained with synchrotron sources, review proposed short- wavelength FEL designs and then present a new design which is capable of over an order of magnitude higher power to the extreme ultraviolet. 17 refs., 10 figs

Short wavelength FELS

Energy Technology Data Exchange (ETDEWEB)

Sheffield, R.L.

1991-01-01

The generation of coherent ultraviolet and shorter wavelength light is presently limited to synchrotron sources. The recent progress in the development of brighter electron beams enables the use of much lower energy electron rf linacs to reach short-wavelengths than previously considered possible. This paper will summarize the present results obtained with synchrotron sources, review proposed short- wavelength FEL designs and then present a new design which is capable of over an order of magnitude higher power to the extreme ultraviolet. 17 refs., 10 figs.

Action spectrum for photobleaching of human lenses by short wavelength visible irradiation

DEFF Research Database (Denmark)

Kessel, Line; Larsen, Michael

2015-01-01

transmission with increasing laser irradiation. CONCLUSIONS: For a 75 year old lens an effect corresponding to elimination of 15 years or more of optical ageing was obtained. This study of the spectral characteristics and intensity needed to bleach the human lens with single-photon laser effects found...... an action-spectrum peak at 420 nm tailing gradually off toward longer wavelengths and more steeply toward shorter wavelengths. The results may be used to guide experiments with two-photon bleaching....

Enhanced UV light detection using wavelength-shifting properties of Silicon nanoparticles

International Nuclear Information System (INIS)

Magill, S.; Xie, J.; Nayfeh, M.; Fizari, M.; Malloy, J.; Maximenko, Y.; Yu, H.

2015-01-01

Detection of UV photons is becoming increasingly necessary with the use of noble gases and liquids in elementary particle experiments. Cerenkov light in crystals and glasses, scintillation light in neutrino, dark matter, and rare decay experiments all require sensitivity to UV photons. New sensor materials are needed that can directly detect UV photons and/or absorb UV photons and re-emit light in the visible range measurable by existing photosensors. It has been shown that silicon nanoparticles are sensitive to UV light in a wavelength range around ∼ 200 nm. UV light is absorbed and re-emitted at wavelengths in the visible range depending on the size of the nanoparticles. Initial tests of the wavelength-shifting properties of silicon nanoparticles are presented here that indicate by placing a film of nanoparticles in front of a standard visible-wavelength detecting photosensor, the response of the sensor is significantly enhanced at wavelengths < 320 nm

A study on UV irradiated HDPE

International Nuclear Information System (INIS)

Sang Haibo; Liu Zimin; Wu Shishan; Shen Jian

2006-01-01

The structure and properties of HDPE irradiated by ultraviolet (UV) in ozone atmosphere were studied by FT-IR, XPS, gel, and water contact angle test. The oxygen-containing groups such as C=O, C-O and C(=O)O were introduced onto high density polyethylene (HDPE) chains through ultraviolet irradiation in ozone atmosphere, their content increased with the UV irradiation time. Under the same UV irradiation conditions, amount of the oxygen-containing groups introduced in ozone atmosphere was more than that in air atmosphere, indicating that the speed of oxygen-containing groups introduced through UV irradiation in ozone atmosphere was faster than that in air. Therefore, HDPE could be quickly functionalized through UV irradiation in ozone atmosphere. There was no gel formed in the HDPE irradiated in ozone atmosphere. After UV irradiation, the water contact angle of HDPE decreased, and its hydrophilicity was improved, suggesting that the compatibility between the irradiated HDPE and polar polymer or inorganic fillers may be better. Compared with HDPE, the temperature of initial weight loss for irradiated HDPE decreased. The structure and properties of irradiated HDPE/CaCO 3 blend were also investigated. The results showed that the compatibility and interfacial action of the irradiated HDPE/CaCO 3 blend were improved compared to that of HDPE/CaCO 3 blend. The mechanical properties of irradiated HDPE/CaCO 3 blend increased with increasing irradiation time. (authors)

Factors affecting color strength of printing on film-coated tablets by UV laser irradiation: TiO2 particle size, crystal structure, or concentration in the film, and the irradiated UV laser power.

Science.gov (United States)

Hosokawa, Akihiro; Kato, Yoshiteru

2011-08-01

The purpose of this article is to study factors affecting color strength of printing on film-coated tablets by ultraviolet (UV) laser irradiation: particle size, crystal structure, or concentration of titanium dioxide (TiO2) in film, and irradiated UV laser power. Hydroxypropylmethylcellulose films containing 4.0% of TiO2, of which BET particle sizes were ranging from 126.1 to 219.8 nm, were irradiated 3.14W of UV laser at a wavelength 355 nm to study effects of TiO2 particle size and crystal structure on the printing. The films containing TiO2 concentration ranging from 1.0 to 7.7% were irradiated 3.14 or 5.39W of the UV laser to study effect of TiO2 concentration on the printing. The film containing 4.0% of TiO2, was irradiated the UV laser up to 6.42W to study effect of the UV laser power on the printing. The color strength of the printed films was estimated by a spectrophotometer as total color difference (dE). Particle size, crystal structure, and concentration of TiO2 in the films did not affect the printing. In the relationship between the irradiated UV laser power and dE, there found an inflection point (1.6W). When the UV laser power was below 1.6W, the films were not printed. When it was beyond the point, total color difference increased linearly in proportion with the irradiated laser power. The color strength of the printing on film was not changed by TiO2 particle size, crystal structure, and concentration, but could be controlled by regulating the irradiated UV laser power beyond the inflection point.

Solar UV Variations During the Decline of Cycle 23

Science.gov (United States)

DeLand, Matthew, T.; Cebula, Richard P.

2011-01-01

Characterization of temporal and spectral variations in solar ultraviolet irradiance over a solar cycle is essential for understanding the forcing of Earth's atmosphere and climate. Satellite measurements of solar UV variability for solar cycles 21, 22, and 23 show consistent solar cycle irradiance changes at key wavelengths (e.g. 205 nm, 250 nm) within instrumental uncertainties. All historical data sets also show the same relative spectral dependence for both short-term (rotational) and long-term (solar cycle) variations. Empirical solar irradiance models also produce long-term solar UV variations that agree well with observational data. Recent UV irradiance data from the Solar Radiation and Climate Experiment (SORCE) Spectral Irradiance Monitor (SIM) and Solar Stellar Irradiance Comparison Experiment (SOLSTICE) instruments covering the declining phase of Cycle 23 present a different picture oflong-term solar variations from previous results. Time series of SIM and SOLSTICE spectral irradiance data between 2003 and 2007 show solar variations that greatly exceed both previous measurements and predicted irradiance changes over this period, and the spectral dependence of the SIM and SOLSTICE variations during these years do not show features expected from solar physics theory. The use of SORCE irradiance variations in atmospheric models yields substantially different middle atmosphere ozone responses in both magnitude and vertical structure. However, short-term solar variability derived from SIM and SOLSTICE UV irradiance data is consistent with concurrent solar UV measurements from other instruments, as well as previous results, suggesting no change in solar physics. Our analysis of short-term solar variability is much less sensitive to residual instrument response changes than the observations of long-term variations. The SORCE long-term UV results can be explained by under-correction of instrument response changes during the first few years of measurements

Low-level laser irradiation protects the chick embryo chorioallantoic membrane from UV cytotoxicity

Directory of Open Access Journals (Sweden)

Hammami Amira

2018-01-01

Full Text Available Low-level laser therapy or photobiomodulation is the medical use of a very low intensity light in the red to near infrared (wavelengths in the range of 630-940 nm. The present work was conducted to explore the effects of both UV and low-level laser irradiation (LLLI on microcirculation using the in vivo model of the chick embryo chorioallantoic membrane (CAM. The effects were assessed by measuring lipid peroxidation and antioxidant enzyme activity. Cell cytotoxicity, survival and intracellular reactive oxygen species (ROS of the CAM were also evaluated. We found that UV irradiation induced alterations of the vessels, leading to bleeding and extravasation. This effect was intensified after 60 min of exposure to UV irradiation, leading to marked edema. UVA irradiation increased cell cytotoxicity as assessed by lactate dehydrogenase (LDH release (56.23% of control and reduced cell viability as assessed by decreased fluorescein diacetate (FDA fluorescence (56.23% of control. Pretreatment with LLLI prior to UV exposure protected the CAM tissue from UV-mediated cell death. This protective effect was supported by the observation of significantly inhibited lipid peroxidation (from 0.3±0.004 for UV, to 0.177±0.012 after LLLI pretreatment, ROS and O2 -production, as indicated by respective dihydrorhodamine (DHR and dihydroethidium (DHE intensities (from 132.78% of control for UVA, to 95.90% of control for L-UV (DHR, and from 127.34% of control for UVA, to 82.03% of control for L-UV (DHE, and by preventing the increase in oxidative activities. LLLI efficiently protected CAM cells from UV-induced oxidative stress and appeared as a safe protective pretreatment against UV irradiation.

First performance results of two novel spectroradiometers developed for fast scanning of solar spectra UV irradiance

Science.gov (United States)

Feister, Uwe; Kaifel, Anton K.; Grewe, Rolf-Dieter; Kaptur, Jasmine; Reutter, Oliver; Wohlfart, Michael; Gericke, Klaus

2003-11-01

Two recently developed different types of fast spectroradiometers measuring solar UV irradiance have been compared in a field campaign: i) the UV spectroradiometer on filter model basis (UV-SPRAFIMO) and ii) the modified version of the spectroradiometer SPECTRO 320D by Instrument Systems. The all-weather UV-SPRAFIMO instrument combines a UV filter radiometer with 5 narrow-band (FBHM ~ 2.0 to 2.5 nm) filters centered within +/- 0.01 nm at 303.5, 309.0, 314.5, 327.0 and 387.0 nm, and an advanced neural network-based model. It allows up to 5 measurements per second to be taken that are averaged within time intervals between 5 and 30 s. The neural networks model that is embedded in the PC-based processing software converts the 5 measured irradiances into a full spectrum from 280 to 450 nm at small wavelength steps (>= 0.05 nm). These spectra can be convoluted with user-defined slit function and integrated to broad-band and action-spectra-weighted irradiance values. Users can access the data stored in the internal data logger by a serial RS232 interface or by a modem and display them on a PC-based Graphical User Interface. The spectroradiometer SPECTRO320D consists of a grating double monochromator with a cooled (-20°C) PMT receiver. The modified instrument version run by DWD uses a Schreder type cosine diffuser that directs the solar global irradiance via quartz fiber optics onto the spectroradiometer's entrance slit. The spectroradiometer used at the campaign was installed in a thermostatted (22 +/- 0.02)°C aluminum box. The modified instrument version performs a spectral scan over the whole UV region in two subsequent parts, with a lower speed in the UV-B than in the UV-A to account for the exponential changes of solar irradiance with increasing wavelengths in the UV-B and for the almost linear change in the UV-A region. In the configuration applied in the comparison, i.e. wavelength steps of 0.2 nm within the scan range from 290 nm to 450 nm, the resulting scan

Effect of remote clouds on surface UV irradiance

Energy Technology Data Exchange (ETDEWEB)

Deguenther, M.; Meerkoetter, R. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Wessling (Germany). Inst. fuer Physik der Atmosphaere

2000-06-01

Clouds affect local surface UV irradiance, even if the horizontal distance from the radiation observation site amounts to several kilometers. In order to investigate this effect, which we call remote clouds effect, a 3-dimensional radiative transfer model is applied. Assuming the atmosphere is subdivided into a quadratic based sector and its surrounding, we quantify the influence of changing cloud coverage within this surrounding from 0% to 100% on surface UV irradiance at the sector center. To work out this remote clouds influence as a function of sector base size, we made some calculations for different sizes between 10 km x 10 km and 100 km x 100 km. It appears that in the case of small sectors (base size {<=}20 km x 20 km) the remote clouds effect is highly variable: Depending on cloud structure, solar zenith angle and wavelength, the surface UV irradiance may be enhanced up to 15% as well as reduced by more than 50%. In contrast, for larger sectors it is always the case that enhancements become smaller by 5% if sector base size exceeds 60 km x 60 km. However, these values are upper estimates of the remote cloud effects and they are found only for special cloud structures. Since these structures might occur but cannot be regarded as typical, different satellite observed cloud formations (horizontal resolution about 1 km x 1 km) have also been investigated. For these more common cloud distributions we find remote cloud effects to be distinctly smaller than the corresponding upper estimates, e.g., for a sector with base size of 25 km x 25 km the surface UV irradiance error due to ignoring the actual remote clouds and replacing their influence with periodic horizontal boundary conditions is less than 3%, whereas the upper estimate of remote clouds effect would suggest an error close to 10%. (orig.)

Increase in the temperature of a laser plasma formed by two-frequency UV - IR irradiation of metal targets

International Nuclear Information System (INIS)

Antipov, A A; Grasyuk, Arkadii Z; Efimovskii, S V; Kurbasov, Sergei V; Losev, Leonid L; Soskov, V I

1998-01-01

An experimental investigation was made of a laser plasma formed by successive irradiation of a metal target with 30-ps UV and IR laser pulses. The UV prepulse, of 266 nm wavelength, was of relatively low intensity (∼ 10 12 W cm -2 ), whereas the intensity of an IR pulse, of 10.6 μm wavelength, was considerably higher (∼3 x 10 14 W cm -2 ) and it was delayed by 0 - 6 ns (the optimal delay was 2 ns). Such two-frequency UV - IR irradiation produced a laser plasma with an electron temperature 5 times higher than that of a plasma created by singe-frequency IR pulses of the same (∼3 x 10 14 W cm -2 ) intensity. (interaction of laser radiation with matter. laser plasma)

Short wavelength laser-plasma interaction experiments in a spherical geometry

International Nuclear Information System (INIS)

Keck, R.L.

1984-01-01

Short wavelength (250 to 500 nm) lasers should provide reduced fast electron preheat and increased laser-pellet coupling efficiency when used as laser fusion drivers. As part of an ongoing effort to study short wavelength laser plasm interaction, six beams of the 24 beam OMEGA Nd-glass laser system have been converted to operation at the third harmonic. This system is capable of providing in excess of 250 Joules of 351 nm light on spherical targets at intensities up to 2 x 10/sup 15/ W/cm/sup 2/. To date, experiments have been performed to study the uniformity of irradiation, laser absorption, fast electron production and preheat, energy transport within the target and underdense plasma instabilities. Both x-ray continuum measurements and Kα line measurements indicate that the absorption is dominated by inverse bremsstrahlung. Electron energy transport has been studied using x-ray burn-through and charge collector measurements. The results show that with 351 nm irradiation ablation pressures of order 100 Mbars are generated at intensities of 10/sup 15/ W/cm/sup 2/

Expression of Nudix hydrolase genes in barley under UV irradiation

Science.gov (United States)

Tanaka, Sayuri; Sugimoto, Manabu; Kihara, Makoto

Seed storage and cultivation should be necessary to self-supply foods when astronauts would stay and investigate during long-term space travel and habitation in the bases on the Moon and Mars. Thought the sunlight is the most importance to plants, both as the ultimate energy source and as an environmental signal regulating growth and development, UV presenting the sunlight can damage many aspects of plant processes at the physiological and DNA level. Especially UV-C, which is eliminated by the stratospheric ozone layer, is suspected to be extremely harmful and give a deadly injury to plants in space. However, the defense mechanism against UV-C irradiation damage in plant cells has not been clear. In this study, we investigated the expression of Nudix hydrolases, which defense plants from biotic / abiotic stress, in barley under UV irradiation. The genes encoding the amino acid sequences, which show homology to those of 28 kinds of Nudix hydrolases in Arabidopsis thaliana, were identified in the barley full-length cDNA library. BLAST analysis showed 14 kinds of barley genes (HvNUDX1-14), which encode the Nudix motif sequence. A phylogenetic tree showed that HvNUDX1, HvNUDX7, HvNUDX9 and HvNUDX11 belonged to the ADP-ribose pyrophosphohydrolase, ADP-sugar pyrophosphohydrolase, NAD(P)H pyrophosphohydrolase and FAD pyrophosphohydrolase subfamilies, respectively, HvNUDX3, HvNUDX6, and HvNUDX8 belonged to the Ap _{n}A pyrophosphohydrolase subfamilies, HvNUDX5 and HvNUDX14 belonged to the coenzyme A pyrophosphohydrolase subfamilies, HvNUDX12 and HvNUDX13 belonged to the Ap _{4}A pyrophosphohydrolase subfamilies. Induction of HvNUDX genes by UV-A (340nm), UV-B (312nm), and UV-C (260nm) were analyzed by quantitative RT-PCR. The results showed that HvNUDX4 was induced by UV-A and UV-B, HvNUDX6 was induced by UV-B and UV-C, and HvNUDX7 and HvNUDX14 were induced by UV-C, significantly. Our results suggest that the response of HvNUDXs to UV irradiation is different by UV

Development of UV absorbing PET through Electron Irradiation

International Nuclear Information System (INIS)

Kim, Jung Woo; Lee, Na Eun; Lim, Hyung San; Park, Yang Jeong; Cho, Sung Oh

2017-01-01

Experiment to increase UV absorbance through electron beam irradiation on PET was performed. Moreover, surface hardness and roughness of each sample were observed to find the key factor increasing UV absorbance. PET sheets were irradiated with an electron beam at various fluences. The irradiated samples, as well as pristine sample, were subjected to UV-visible spectral study(UV-Vis), pencil hardness test, and scanning electron microscopy(SEM) experiment. In this study, PET samples irradiated at several conditions were analyzed through various measurements. UV absorbance-another meaning of transmittance in this study- of irradiated PET sample increased compared with pristine sample as fluence was increased in UV-Visible spectroscopy experiment.

Omega: A 24-beam UV irradiation facility

International Nuclear Information System (INIS)

Richardson, M.C.; Beich, W.; Delettrez, J.

1985-01-01

The authors report on the characterization and performance of the 24-beam Omega laser facility under full third harmonic (351-nm) upconversion. This system provides for the first time a multibeam laser facility for the illumination of spherical targets with UV laser light in symmetric irradiation conditions with energies in the kilojoule range. This facility is capable of providing sufficient irradiation uniformity to test concepts of direct drive laser fusion with UV-driven ablation targets. The results of initial studies of ablatively driven DT-fueled glass microballoon targets will be described. The 24-beam Omega Nd:phosphate glass facility is capable of providing at 1054 nm output powers in excess of 10 TW in short ( 10 4 full system shots to date) irradiation facility with beam synchronism of approx. =3 psec, beam placement accuracy on target of 10 μm, and interbeam energy variance of approx. =2%. From measured target plane intensity distributions, overall illumination uniformity with tangentially focused beams is estimated to be approx. =5%. In 1984, a symmetric set of six beams was upconverted to 351-nm radiation using the polarization-mismatch scheme developed by Craxton. Monolithic cells of 20-cm clear aperture containing both frequency and doubler and tripler type II KDP crystals in index-matching propylene carbonate liquid were incorporated to output of six of the Omega beams with a full set of UV beam diagnostics

Stimulation of DNA synthesis by 340nm/ 351nm UV laser irradiation

International Nuclear Information System (INIS)

Meldrum, R.A.; Wharton, C.W.

1991-01-01

During preliminary experiments designed to test the feasibility of using a 'caged' DNA break trapping agent, the authors observed a stimulation of incorporation of 3 H-thymidine into DNA when cells were irradiated with low doses (100-1000J/m 2 ) of 351nm UV laser irradiation. This wavelength is used to photolyse 'caged' dideoxynucleotides in our fast time course measurements of DNA repair in mammalian cells. The dose at which this stimulation was observed is well below that at which measurable damage is detected. (author)

Expression of UV-irradiated adenovirus in normal and UV-sensitive Chinese hamster ovary cells

International Nuclear Information System (INIS)

Rainbow, A.J.

1985-01-01

The chinese hamster ovary (CHO) cell mutants UV-20, UV-24, and UV-41 are abnormally sensitive to UV and harbour various defects lin their ability to repair cellular DNA. This study has examined the expression of UV-irradiated AD2 in these cells. HCR of UV-irradiated Ad2, as measured by viral structural antigen (Vag) formation or progeny production, was found to be similar for the normal and the UV-sensitive CHO strains. UV-irradiation of Ad2 (1200 J/m/sup 2/) resulted in a delay of Vag expression of 18 hours in normal human fibroblasts, which is thought to reflect the time required for removal of UV-induced lesions from the DNA before viral DNA synthesis can proceed. However, a similar UV-irradiation of Ad2 did not result in a delay of Vag expression for infection of CHO cells, suggesting that UV-induced lesions in Ad2 DNA do not inhibit its replication in CHO cells. These results indicate a fundamental difference in the processing of UV-irradiated AD2-DNA in CHO as compared to human cells

Towards short wavelengths FELs workshop

International Nuclear Information System (INIS)

Ben-Zvi, I.; Winick, H.

1993-01-01

This workshop was caged because of the growing perception in the FEL source community that recent advances have made it possible to extend FEL operation to wavelengths about two orders of magnitude shorter than the 240 nm that has been achieved to date. In addition short wavelength FELs offer the possibilities of extremely high peak power (several gigawatts) and very short pulses (of the order of 100 fs). Several groups in the USA are developing plans for such short wavelength FEL facilities. However, reviewers of these plans have pointed out that it would be highly desirable to first carry out proof-of-principle experiments at longer wavelengths to increase confidence that the shorter wavelength devices will indeed perform as calculated. The need for such experiments has now been broadly accepted by the FEL community. Such experiments were the main focus of this workshop as described in the following objectives distributed to attendees: (1) Define measurements needed to gain confidence that short wavelength FELs will perform as calculated. (2) List possible hardware that could be used to carry out these measurements in the near term. (3) Define a prioritized FEL physics experimental program and suggested timetable. (4) Form collaborative teams to carry out this program

Towards short wavelengths FELs workshop

Science.gov (United States)

Ben-Zvi, I.; Winick, H.

1993-11-01

This workshop was caged because of the growing perception in the FEL source community that recent advances have made it possible to extend FEL operation to wavelengths about two orders of magnitude shorter than the 240 nm that has been achieved to date. In addition short wavelength FEL's offer the possibilities of extremely high peak power (several gigawatts) and very short pulses (of the order of 100 fs). Several groups in the USA are developing plans for such short wavelength FEL facilities. However, reviewers of these plans have pointed out that it would be highly desirable to first carry out proof-of-principle experiments at longer wavelengths to increase confidence that the shorter wavelength devices will indeed perform as calculated. The need for such experiments has now been broadly accepted by the FEL community. Such experiments were the main focus of this workshop as described in the following objectives distributed to attendees: (1) Define measurements needed to gain confidence that short wavelength FEL's will perform as calculated. (2) List possible hardware that could be used to carry out these measurements in the near term. (3) Define a prioritized FEL physics experimental program and suggested timetable. (4) Form collaborative teams to carry out this program.

Investigation of the influence of UV irradiation on collagen thin films by AFM imaging

Energy Technology Data Exchange (ETDEWEB)

Stylianou, Andreas, E-mail: styliand@mail.ntua.gr; Yova, Dido; Alexandratou, Eleni

2014-12-01

Collagen is the major fibrous extracellular matrix protein and due to its unique properties, it has been widely used as biomaterial, scaffold and cell-substrate. The aim of the paper was to use Atomic Force Microscopy (AFM) in order to investigate well-characterized collagen thin films after ultraviolet light (UV) irradiation. The films were also used as in vitro culturing substrates in order to investigate the UV-induced alterations to fibroblasts. A special attention was given in the alteration on collagen D-periodicity. For short irradiation times, spectroscopy (fluorescence/absorption) studies demonstrated that photodegradation took place and AFM imaging showed alterations in surface roughness. Also, it was highlighted that UV-irradiation had different effects when it was applied on collagen solution than on films. Concerning fibroblast culturing, it was shown that fibroblast behavior was affected after UV irradiation of both collagen solution and films. Furthermore, after a long irradiation time, collagen fibrils were deformed revealing that collagen fibrils are consisting of multiple shells and D-periodicity occurred on both outer and inner shells. The clarification of the effects of UV light on collagen and the induced modifications of cell behavior on UV-irradiated collagen-based surfaces will contribute to the better understanding of cell–matrix interactions in the nanoscale and will assist in the appropriate use of UV light for sterilizing and photo-cross-linking applications. - Highlights: • Collagen thin films were formed and exposed in UV irradiation. • Collagen thin films were formed from UV-irradiated collagen solution. • Nanocharacterization of collagen thin films by AFM • Fluorescence and absorption spectroscopy studies on collagen films • Investigation of fibroblast response on collagen films.

Investigation of the influence of UV irradiation on collagen thin films by AFM imaging

International Nuclear Information System (INIS)

Stylianou, Andreas; Yova, Dido; Alexandratou, Eleni

2014-01-01

Collagen is the major fibrous extracellular matrix protein and due to its unique properties, it has been widely used as biomaterial, scaffold and cell-substrate. The aim of the paper was to use Atomic Force Microscopy (AFM) in order to investigate well-characterized collagen thin films after ultraviolet light (UV) irradiation. The films were also used as in vitro culturing substrates in order to investigate the UV-induced alterations to fibroblasts. A special attention was given in the alteration on collagen D-periodicity. For short irradiation times, spectroscopy (fluorescence/absorption) studies demonstrated that photodegradation took place and AFM imaging showed alterations in surface roughness. Also, it was highlighted that UV-irradiation had different effects when it was applied on collagen solution than on films. Concerning fibroblast culturing, it was shown that fibroblast behavior was affected after UV irradiation of both collagen solution and films. Furthermore, after a long irradiation time, collagen fibrils were deformed revealing that collagen fibrils are consisting of multiple shells and D-periodicity occurred on both outer and inner shells. The clarification of the effects of UV light on collagen and the induced modifications of cell behavior on UV-irradiated collagen-based surfaces will contribute to the better understanding of cell–matrix interactions in the nanoscale and will assist in the appropriate use of UV light for sterilizing and photo-cross-linking applications. - Highlights: • Collagen thin films were formed and exposed in UV irradiation. • Collagen thin films were formed from UV-irradiated collagen solution. • Nanocharacterization of collagen thin films by AFM • Fluorescence and absorption spectroscopy studies on collagen films • Investigation of fibroblast response on collagen films

Pulsed UV laser-induced modifications in optical and structural characteristics of alpha-irradiated PM-355 SSNTD.

Science.gov (United States)

Alghamdi, S S; Farooq, W A; Baig, M R; Algarawi, M S; Alrashidi, Talal Mohammed; Ali, Syed Mansoor; Alfaramawi, K

2017-10-01

Pre- and postalpha-exposed PM-355 detectors were irradiated using UV laser with different number of pulses (100, 150, 200, 300, and 400). UV laser beam energy of 20mJ per pulse with a pulse width of 9ns was incident on an area of 19.6mm 2 of the samples. XRD spectra indicated that for both reference and UV-irradiated samples, the structure is amorphous, but the crystallite size increases upon UV irradiation. The same results were obtained from SEM analysis. Optical properties of PM-355 polymeric solid-state nuclear track detectors were also investigated. Absorbance measurements for all PM-355 samples in the range of 200-400nm showed that the absorption edge had a blue shift up to a certain value, and then, it had an oscillating behavior. Photoluminescence spectra of PM-355 at 250nm revealed a decrease in the broadband peak intensity as a function of the number of UV pulses, while the wavelengths corresponding to the peaks had random shifts. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of visible and UV irradiation on the aggregation stability of CdTe quantum dots

International Nuclear Information System (INIS)

Tsipotan, Aleksei S.; Gerasimova, Marina A.; Aleksandrovsky, Aleksandr S.; Zharkov, Sergey M.; Slabko, Vitaliy V.

2016-01-01

The possibility of controlling the aggregation stability of CdTe quantum dots (QDs) stabilized by thioglycolic acid (TGA) is important for implementation of quasi-resonant laser-induced self-assembly. This study examines the influence of irradiation by the UV as well as by the visible light on the photostimulated aggregation of QDs. Different photochemical mechanisms are identified, depending on whether light wavelength falls into an interband transition or the first exciton transition. Irradiation by visible light does not lead to changes in the absorption spectra but decreases luminescence intensity through the detachment of TGA and the formation of dangling bonds, leading to the creation of radiativeless relaxation centers. UV irradiation (in the 300–370 nm range), at an intensity of 0.4 W/cm"2, initially (during the first 75 min) leads to the degradation of the stabilizer and QDs’ surface. After 75 min of combined UV and visible light irradiation, a gradual increase in spontaneous aggregation takes place, testifying excessive decrease in stabilizing potential barrier height. Hence, the laser-induced self-assembly of CdTe QDs is recommended to be performed over a time period of between 80 and 100 min after the beginning of low-intensity UV irradiation under conditions equivalent to those applied in this study.

Effect of Bifidobacterium breve B-3 on skin photoaging induced by chronic UV irradiation in mice.

Science.gov (United States)

Satoh, T; Murata, M; Iwabuchi, N; Odamaki, T; Wakabayashi, H; Yamauchi, K; Abe, F; Xiao, J Z

2015-01-01

Probiotics have been shown to have a preventative effect on skin photoaging induced by short term UV irradiation, however, the underlying mechanisms and the effect of probiotics on skin photoaging induced by chronic UV irradiation remain unclear. In this study, we investigated the effect of Bifidobacterium breve B-3 on skin photoaging induced by chronic UV irradiation in hairless mice. Mice were irradiated with UVB three times weekly and orally administered B. breve B-3 (2×10(9) cfu/mouse /day) for 7 weeks. Nonirradiated mice and UVB-irradiated mice without probiotic treatment were used as controls. B. breve B-3 significantly suppressed the changes of transepidermal water loss, skin hydration, epidermal thickening and attenuated the damage to the tight junction structure and basement membrane induced by chronic UVB irradiation. Administration of B. breve B-3 tended to suppress the UV-induced interleukin-1β production in skin (P=0.09). These results suggest that B. breve B-3 could potentially be used to prevent photoaging induced by chronic UV irradiation.

Enhanced UV light detection using a p-terphenyl wavelength shifter

Science.gov (United States)

Joosten, S.; Kaczanowicz, E.; Ungaro, M.; Rehfuss, M.; Johnston, K.; Meziani, Z.-E.

2017-10-01

UV-glass photomultiplier tubes (PMTs) have poor photon detection efficiency for wavelengths below 300 nm due to the opaqueness of the window material. Costly quartz PMTs could be used to enhance the efficiency below 300 nm. A less expensive solution that dramatically improves this efficiency is the application of a thin film of a p-terphenyl (PT) wavelength shifter on UV-glass PMTs. This improvement was quantified for Photonis XP4500B PMTs for wavelengths between 200 nm and 400 nm. The gain factor ranges up to 5 . 4 ± 0 . 5 at a wavelength of 215 nm, with a material load of 110 ± 10 μg /cm2 (894 nm). The wavelength shifter was found to be fully transparent for wavelengths greater than 300 nm. The resulting gain in detection efficiency, when used in a typical C̆erenkov counter, was estimated to be of the order of 40%. Consistent coating quality was assured by a rapid gain testing procedure using narrow-band UV LEDs. Based on these results, 200 Photonis XP4500B PMTs were treated with PT for the upgraded low-threshold C̆erenkov counter (LTCC) to be used in the CEBAF Large Acceptance Spectrometer upgraded detector (CLAS12) at the Thomas Jefferson National Accelerator Facility.

Modeling the natural UV irradiation and comparative UV measurements at Moussala BEO (BG)

Science.gov (United States)

Tyutyundzhiev, N.; Angelov, Ch; Lovchinov, K.; Nitchev, Hr; Petrov, M.; Arsov, T.

2018-03-01

Studies of and modeling the impact of natural UV irradiation on the human population are of significant importance for human activity and economics. The sharp increase of environmental problems – extraordinary temperature changes, solar irradiation abnormalities, icy rains – raises the question of developing novel means of assessing and predicting potential UV effects. In this paper, we discuss new UV irradiation modeling based on recent real-time measurements at Moussala Basic Environmental Observatory (BEO) on Moussala Peak (2925 m ASL) in Rila Mountain, Bulgaria, and highlight the development and initial validation of portable embedded devices for UV-A, UV-B monitoring using open-source software architecture, narrow bandpass UV sensors, and the popular Arduino controllers. Despite the high temporal resolution of the VIS and UV irradiation measurements, the results obtained reveal the need of new assumptions in order to minimize the discrepancy with available databases.

Laser spectroscopy on atoms and ions using short-wavelength radiation

International Nuclear Information System (INIS)

Larsson, Joergen.

1994-05-01

Radiative properties and energy structures in atoms and ions have been investigated using UV/VUV radiation. In order to obtain radiation at short wavelengths, frequency mixing of pulsed laser radiation in crystals and gases has been performed using recently developed frequency-mixing schemes. To allow the study of radiative lifetimes shorter than the pulses from standard Q-switched lasers, different techniques have been used to obtain sufficiently short pulses. The Hanle effect has been employed following pulsed laser excitation for the same purpose. High-resolution spectroscopic techniques have been adapted for use with the broad-band, pulsed laser sources which are readily available in the UV/VUV spectral region. In order to investigate sources of radiation in the XUV and soft X-ray spectral regions, harmonic generation in rare gases has been studied. The generation of coherent radiation by the interaction between laser radiation and relativistic electrons in a synchrotron storage ring has also been investigated. 60 refs

Transformation of UV-hypersensitive Chinese hamster ovary cell mutants with UV-irradiated plasmids

International Nuclear Information System (INIS)

Nairn, R.S.; Humphrey, R.M.; Adair, G.M.

1988-01-01

Transfection of UV-hypersensitive, DNA repair-deficient Chinese hamster ovary (CHO) cell lines and parental, repair-proficient CHO cells with UV-irradiated pHaprt-1 or pSV2gpt plasmids resulted in different responses by recipient cell lines to UV damage in transfected DNA. Unlike results reported for human cells, UV irradiation of transfecting DNA did not stimulate genetic transformation of CHO recipient cells. In repair-deficient CHO cells, proportionally fewer transformants were produced with increasing UV damage than in repair-proficient cells in transfections with UV-irradiated hamster adenine phosphoribosyltransferase (APRT) gene contained in plasmid pHaprt-1. Transfection of CHO cells with UV-irradiated pSV2gpt resulted in neither decline in transformation frequencies in repair-deficient cell lines relative to repair-proficient cells nor stimulation of genetic transformation by UV damage in the plasmid. Blot hybridization analysis of DNA samples isolated from transformed cells showed no dramatic changes in copy number or arrangement of transfected plasmid DNA with increasing UV dose. The authors conclude responses of recipient cells to UV-damaged transfecting plasmids depend on type of recipient cell and characteristics of the genetic sequence used for transfection. (author)

UV-irradiation effects on polyester nuclear track detector

International Nuclear Information System (INIS)

Agarwal, Chhavi; Kalsi, P.C.

2010-01-01

The effects of UV irradiation (λ=254 nm) on polyester nuclear track detector have been investigated employing bulk-etch technique, UV-visible spectrophotometry and infra-red spectrometry (FTIR). The activation energy values for bulk-etching were found to decrease with the UV-irradiation time indicating the scission of the polymer. Not much shift in the absorption edge due to UV irradiation was seen in the UV-visible spectra. FTIR studies also indicate the scission of the chemical bonds, thereby further validating the bulk-etch rate results.

Reconstruction of solar spectral surface UV irradiances using radiative transfer simulations.

Science.gov (United States)

Lindfors, Anders; Heikkilä, Anu; Kaurola, Jussi; Koskela, Tapani; Lakkala, Kaisa

2009-01-01

UV radiation exerts several effects concerning life on Earth, and spectral information on the prevailing UV radiation conditions is needed in order to study each of these effects. In this paper, we present a method for reconstruction of solar spectral UV irradiances at the Earth's surface. The method, which is a further development of an earlier published method for reconstruction of erythemally weighted UV, relies on radiative transfer simulations, and takes as input (1) the effective cloud optical depth as inferred from pyranometer measurements of global radiation (300-3000 nm); (2) the total ozone column; (3) the surface albedo as estimated from measurements of snow depth; (4) the total water vapor column; and (5) the altitude of the location. Reconstructed daily cumulative spectral irradiances at Jokioinen and Sodankylä in Finland are, in general, in good agreement with measurements. The mean percentage difference, for instance, is mostly within +/-8%, and the root mean square of the percentage difference is around 10% or below for wavelengths over 310 nm and daily minimum solar zenith angles (SZA) less than 70 degrees . In this study, we used pseudospherical radiative transfer simulations, which were shown to improve the performance of our method under large SZA (low Sun).

Optimizing UV Index determination from broadband irradiances

Science.gov (United States)

Tereszchuk, Keith A.; Rochon, Yves J.; McLinden, Chris A.; Vaillancourt, Paul A.

2018-03-01

A study was undertaken to improve upon the prognosticative capability of Environment and Climate Change Canada's (ECCC) UV Index forecast model. An aspect of that work, and the topic of this communication, was to investigate the use of the four UV broadband surface irradiance fields generated by ECCC's Global Environmental Multiscale (GEM) numerical prediction model to determine the UV Index. The basis of the investigation involves the creation of a suite of routines which employ high-spectral-resolution radiative transfer code developed to calculate UV Index fields from GEM forecasts. These routines employ a modified version of the Cloud-J v7.4 radiative transfer model, which integrates GEM output to produce high-spectral-resolution surface irradiance fields. The output generated using the high-resolution radiative transfer code served to verify and calibrate GEM broadband surface irradiances under clear-sky conditions and their use in providing the UV Index. A subsequent comparison of irradiances and UV Index under cloudy conditions was also performed. Linear correlation agreement of surface irradiances from the two models for each of the two higher UV bands covering 310.70-330.0 and 330.03-400.00 nm is typically greater than 95 % for clear-sky conditions with associated root-mean-square relative errors of 6.4 and 4.0 %. However, underestimations of clear-sky GEM irradiances were found on the order of ˜ 30-50 % for the 294.12-310.70 nm band and by a factor of ˜ 30 for the 280.11-294.12 nm band. This underestimation can be significant for UV Index determination but would not impact weather forecasting. Corresponding empirical adjustments were applied to the broadband irradiances now giving a correlation coefficient of unity. From these, a least-squares fitting was derived for the calculation of the UV Index. The resultant differences in UV indices from the high-spectral-resolution irradiances and the resultant GEM broadband irradiances are typically within 0

Effect of visible and UV irradiation on the aggregation stability of CdTe quantum dots

Energy Technology Data Exchange (ETDEWEB)

Tsipotan, Aleksei S.; Gerasimova, Marina A.; Aleksandrovsky, Aleksandr S., E-mail: aleksandrovsky@kirensky.ru; Zharkov, Sergey M.; Slabko, Vitaliy V. [Siberian Federal University (Russian Federation)

2016-11-15

The possibility of controlling the aggregation stability of CdTe quantum dots (QDs) stabilized by thioglycolic acid (TGA) is important for implementation of quasi-resonant laser-induced self-assembly. This study examines the influence of irradiation by the UV as well as by the visible light on the photostimulated aggregation of QDs. Different photochemical mechanisms are identified, depending on whether light wavelength falls into an interband transition or the first exciton transition. Irradiation by visible light does not lead to changes in the absorption spectra but decreases luminescence intensity through the detachment of TGA and the formation of dangling bonds, leading to the creation of radiativeless relaxation centers. UV irradiation (in the 300–370 nm range), at an intensity of 0.4 W/cm{sup 2}, initially (during the first 75 min) leads to the degradation of the stabilizer and QDs’ surface. After 75 min of combined UV and visible light irradiation, a gradual increase in spontaneous aggregation takes place, testifying excessive decrease in stabilizing potential barrier height. Hence, the laser-induced self-assembly of CdTe QDs is recommended to be performed over a time period of between 80 and 100 min after the beginning of low-intensity UV irradiation under conditions equivalent to those applied in this study.

Evaluating UV-C LED disinfection performance and investigating potential dual-wavelength synergy.

Science.gov (United States)

Beck, Sara E; Ryu, Hodon; Boczek, Laura A; Cashdollar, Jennifer L; Jeanis, Kaitlyn M; Rosenblum, James S; Lawal, Oliver R; Linden, Karl G

2017-02-01

A dual-wavelength UV-C LED unit, emitting at peaks of 260 nm, 280 nm, and the combination of 260|280 nm together was evaluated for its inactivation efficacy and energy efficiency at disinfecting Escherichia coli, MS2 coliphage, human adenovirus type 2 (HAdV2), and Bacillus pumilus spores, compared to conventional low-pressure and medium-pressure UV mercury vapor lamps. The dual-wavelength unit was also used to measure potential synergistic effects of multiple wavelengths on bacterial and viral inactivation and DNA and RNA damage. All five UV sources demonstrated similar inactivation of E. coli. For MS2, the 260 nm LED was most effective. For HAdV2 and B. pumilus, the MP UV lamp was most effective. When measuring electrical energy per order of reduction, the LP UV lamp was most efficient for inactivating E. coli and MS2; the LP UV and MP UV mercury lamps were equally efficient for HAdV2 and B. pumilus spores. Among the UV-C LEDs, there was no statistical difference in electrical efficiency for inactivating MS2, HAdV2, and B. pumilus spores. The 260 nm and 260|280 nm LEDs had a statistical energy advantage for E. coli inactivation. For UV-C LEDs to match the electrical efficiency per order of log reduction of conventional LP UV sources, they must reach efficiencies of 25-39% or be improved on by smart reactor design. No dual wavelength synergies were detected for bacterial and viral inactivation nor for DNA and RNA damage. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of UV irradiation and UV/chlorine co-exposure on natural organic matter in water

International Nuclear Information System (INIS)

Liu, Wei; Zhang, Zaili; Yang, Xin; Xu, Yiyue; Liang, Yongmei

2012-01-01

The effects of co-exposure to ultraviolet (UV) irradiation (with either low- or medium-pressure UV lamps) and free chlorine (chloramine) at practical relevant conditions on changes in natural organic matter (NOM) properties were investigated using four waters. The changes were characterized using the specific disinfection by-product formation potential (SDBPFP), specific total organic halogen formation potential (STOXFP), differential UV absorbance (∆UVA), and size-exclusion chromatography (SEC). The results for exposure to UV irradiation alone and for samples with no exposure were also obtained. The SDBPFPs in all UV-irradiated NOM waters observed were higher than those of non-irradiated samples. UV irradiation led to increases in STOXFPs as a result of chlorination, but no changes, or only small decreases, from chloramination. UV irradiation alone led to positive ∆UVA spectra of the four NOM waters; co-exposure to UV and chlorine gave larger negative ∆UVA spectra than those obtained by chlorine exposure alone. No obvious changes in SEC results were observed for samples only irradiated with UV light; co-exposure gave no detectable changes in the abundances of small fractions for exposure to chlorine only. Both UV photooxidation and photocatalytic oxidation appear to affect the reactivity of the NOM toward subsequent chlorination, and the magnitude of the changes is generally greater for medium-pressure lamps than for low-pressure lamps. These results suggest that applying UV disinfection technology to a particular source may not always be disinfection by-product-problem-free, and the interactions between UV light, chlorine, and NOM may need to be considered. - Highlights: ► We discussed the effects of co-exposure to UV light and chlorine on properties of natural organic matters in waters. ► UV irradiation led to increases in SDBPFP and STOXFP of NOM waters from chlorination. ► We suggest that applying an UV disinfection technology to a particular

Effect of UV irradiation on cutaneous cicatrices

DEFF Research Database (Denmark)

Due, Eva; Rossen, Kristian; Sorensen, Lars Tue

2007-01-01

The aim of this study was to examine the effect of ultraviolet (UV) irradiation on human cutaneous cicatrices. In this randomized, controlled study, dermal punch biopsy wounds served as a wound healing model. Wounds healed by primary or second intention and were randomized to postoperative solar UV...... postoperatively, UV-irradiated cicatrices healing by second intention: (i) were significantly pointed out as the most disfiguring; (ii) obtained significantly higher scores of colour, infiltration and cicatrix area; and (iii) showed significantly higher increase in skin-reflectance measurements of skin......-pigmentation vs. non-irradiated cicatrices. No histological, immunohistochemical or biochemical differences were found. In conclusion, postoperative UV exposure aggravates the clinical appearance of cicatrices in humans....

Effects of UV-C irradiation on development of goldfish embryos

International Nuclear Information System (INIS)

Wu Jian; Dai Guifu; Zhang Fengqiu; Lu Lei

2005-01-01

Goldfish embryos at five different developmental stages, from fertilized eggs to heat beating stage, were irradiated by UV rays, and hatching rate, darkly pigmented eye rate and abnormal embryo rate of the irradiated embryos were investigated. Being subjected to very low amount (≤3 min.) of the UV irradiation, the embryos earlier than gastrula stage showed hormesis. However, the embryos at gastrula or heart beating stage were very sensitive to UV irradiation, showing just damage effect, which was very strong even at very low amount of the UV irradiation. The results also showed that development of the gastrula embryos irradiated by the UV rays stopped before darkly pigmented eye state, whereas embryos irradiated at heart beating stage by the UV rays could develop to the darkly pigmented eye stage, though they could not hatch out. (authors)

Alteration in murine epidermal Langerhans cell population by various UV irradiations: quantitative and morphologic studies on the effects of various wavelengths of monochromatic radiation on Ia-bearing cells

International Nuclear Information System (INIS)

Obata, M.; Tagami, H.

1985-01-01

The present study was undertaken in order to clarify the exact mode of the Langerhans cell (LC) depleting process caused by UV irradiation. Following irradiation with a single dose of various wavelengths of monochromatic UV radiation (UVR), the number of Ia-positive cells were studied in mouse epidermal sheets quantitatively, particularly with regard to dose-response relationships, action spectrum, and time course change. In addition, morphologic alterations of these cells were studied using electron- and immunoelectron microscopy (EM and IEM). The authors obtained the following results after a single dose of UVB radiation (200 mJ/cm2 of 300 nm) or PUVA (1% of 8-methoxypsoralen (8-MOP) 20 microliter and 1 J/cm2 of 360 nm): (1) EM and IEM showed that while some LCs simply lost their Ia marker without any structural alterations, the majority of the LCs disappeared due to actual cell damage. (2) During an ''injury phase,'' the initial 48 h, and a ''recovery phase,'' lasting from 4-14 days after irradiation, enlargement of the size of remaining Ia-positive LCs occurred. The degree of enlargement was closely related to the degree of reduction in number, suggesting a process compensating for the loss of the LC population. (3) It was found that the recovery rate of LCs after irradiation damage was slower than that of keratinocytes, indicating different cell kinetics between these distinct cell populations in the epidermis, i.e., restoration of LCs after irradiation seems to be achieved at least partially through a repopulation process originating in the bone marrow

Semi-conservative synthesis of DNA in UV-sensitive mutant cells of Chinese hamster after UV-irradiation

International Nuclear Information System (INIS)

Vikhanskaya, F.L.; Khrebtukova, I.A.; Manuilova, E.S.

1985-01-01

A study was made of the rate of semi-conservative DNA synthesis in asynchronous UV-resistant (clone V79) and UV-sensitive clones (VII and XII) of Chinese hamster cells after UV-irradiation. In all 3 clones studied, UV-irradiation (5-30 J/m 2 ) induced a decrease in the rate of DNA synthesis during the subsequent 1-2 h. In the resistant clone (V79) recovery of DNA synthesis rate started after the first 2 h post-irradiation (5 J/m 2 ) and by the 3rd hour reached its maximum value, which constituted 70% of that observed in control, non-irradiated cells. The UV-sensitive mutant clones VII and XII showed no recovery in the rate of DNA synthesis during 6-7 h post-irradiation. The results obtained show that the survival of cells is correlated with the ability of DNA synthesis to recover after UV-irradiation in 3 clones studied. The observed recovery of UV-inhibited DNA synthesis in mutant clones may be due to certain defects in DNA repair. (orig.)

Effect of UV laser irradiation on tissue

International Nuclear Information System (INIS)

Nakayama, Takeyoshi; Kubo, Uichi

1992-01-01

Laser-tissue interactions have been investigated through Electron Probe Micro Analysis (EPMA), UV-visible optical absorption and Fourier Transform Infrared Spectroscopy (FTIR). Three excimer lasers, ArF, KrF and XeCl, were used to irradiate tissue; cow thighbone and gelatin thin film. Features of UV laser irradiation are described. (author)

Microbial inactivation and cytotoxicity evaluation of UV irradiated coconut water in a novel continuous flow spiral reactor.

Science.gov (United States)

Bhullar, Manreet Singh; Patras, Ankit; Kilanzo-Nthenge, Agnes; Pokharel, Bharat; Yannam, Sudheer Kumar; Rakariyatham, Kanyasiri; Pan, Che; Xiao, Hang; Sasges, Michael

2018-01-01

A continuous-flow UV reactor operating at 254nm wave-length was used to investigate inactivation of microorganisms including bacteriophage in coconut water, a highly opaque liquid food. UV-C inactivation kinetics of two surrogate viruses (MS2, T1UV) and three bacteria (E. coli ATCC 25922, Salmonella Typhimurium ATCC 13311, Listeria monocytogenes ATCC 19115) in buffer and coconut water were investigated (D 10 values ranging from 2.82 to 4.54mJ·cm -2 ). A series of known UV-C doses were delivered to the samples. Inactivation levels of all organisms were linearly proportional to UV-C dose (r 2 >0.97). At the highest dose of 30mJ·cm -2 , the three pathogenic organisms were inactivated by >5 log 10 (pUV-C irradiation effectively inactivated bacteriophage and pathogenic microbes in coconut water. The inactivation kinetics of microorganisms were best described by log linear model with a low root mean square error (RMSE) and high coefficient of determination (r 2 >0.97). Models for predicting log reduction as a function of UV-C irradiation dose were found to be significant (pUV-C treatment did not generate cytotoxic compounds in the coconut water. This study clearly demonstrated that high levels of inactivation of pathogens can be achieved in coconut water, and suggested potential method for UV-C treatment of other liquid foods. This research paper provides scientific evidence of the potential benefits of UV-C irradiation in inactivating bacterial and viral surrogates at commercially relevant doses of 0-120mJ·cm -2 . The irradiated coconut water showed no cytotoxic effects on normal intestinal and healthy mice liver cells. UV-C irradiation is an attractive food preservation technology and offers opportunities for horticultural and food processing industries to meet the growing demand from consumers for healthier and safe food products. This study would provide technical support for commercialization of UV-C treatment of beverages. Copyright © 2017 Elsevier Ltd. All

Sensitivity of bacteria to photoactivated titanium dioxide in comparison with UV irradiation

International Nuclear Information System (INIS)

Kersters, Ilse; De Keyser, Tilly; Verstraete, Willy

1998-01-01

Titanium dioxide was used as a photocatalyst to generate hydroxyl radicals in a flowthrough water reactor. Experiments were performed with cultures of Aeromonas hydrophila AWWX1 and Pseudomonas fluorescens R 2 f to evaluate the disinfection capabilities of the reactor. Although a decrease in viable counts was observed with long-wavelength (λ=370 nm) irradiated TiO 2 pellets, direct UV 254 irradiation seems a superior technology for the disinfection of transparent potable water since the viable counts of the test strains declined stronger (2-5 logs) and faster (20x) in UV 254 -treated water than in photoactivated TiO 2 -treated water. Outdoor tests conducted in the summer noonday sun showed that the viable counts of Aeromonas hydrophila AWWX1 decreased strongly (ca 5 log units) in transparent and turbid water samples (750 NTU) exposed to natural sunlight (47,000 lux). The addition of TiO 2 to the solar irradiated waters did not influence the die-off of the strain. These observations indicate that the photocatalytic approach does not offer real prospects as an alternative technology for the disinfection of drinking water. (author)

Photodegradation of pharmaceuticals in the aquatic environment by sunlight and UV-A, -B and -C irradiation.

Science.gov (United States)

Kawabata, Kohei; Sugihara, Kazumi; Sanoh, Seigo; Kitamura, Shigeyuki; Ohta, Shigeru

2013-01-01

In order to investigate the effect of sunlight on the persistence and ecotoxicity of pharmaceuticals contaminating the aquatic environment, we exposed nine pharmaceuticals (acetaminophen (AA), amiodarone (AM), dapsone (DP), dexamethasone (DX), indomethacin (IM), naproxen (NP), phenytoin (PH), raloxifene (RL), and sulindac (SL)) in aqueous media to sunlight and to ultraviolet (UV) irradiation at 254, 302 or 365 nm (UV-C, UV-B or UV-A, respectively). Degradation of the pharmaceuticals was monitored by means of high-performance liquid chromatography (HPLC). Sunlight completely degraded AM, DP and DX within 6 hr, and partly degraded the other pharmaceuticals, except AA and PH, which were not degraded. Similar results were obtained with UV-B, while UV-A was less effective (both UV-A and -B are components of sunlight). All the pharmaceuticals were photodegraded by UV-C, which is used for sterilization in sewage treatment plants. Thus, the photodegradation rates of pharmaceuticals are dependent on both chemical structure and the wavelength of UV exposure. Toxicity assay using the luminescent bacteria test (ISO11348) indicated that UV irradiation reduced the toxicity of some pharmaceuticals to aquatic organisms by decreasing their amount (photodegradation) and increased the toxicity of others by generating toxic photoproduct(s). These results indicate the importance of investigating not only parent compounds, but also photoproducts in the risk assessment of pharmaceuticals in aquatic environments.

UV irradiation and autoclave treatment for elimination of contaminating DNA from laboratory consumables.

Science.gov (United States)

Gefrides, Lisa A; Powell, Mark C; Donley, Michael A; Kahn, Roger

2010-02-01

Laboratories employ various approaches to ensure that their consumables are free of DNA contamination. They may purchase pre-treated consumables, perform quality control checks prior to casework, and use in-house profile databases for contamination detection. It is better to prevent contamination prior to DNA typing than identify it after samples are processed. To this end, laboratories may UV irradiate or autoclave consumables prior to use but treatment procedures are typically based on killing microorganisms and not on the elimination of DNA. We report a systematic study of UV and autoclave treatments on the persistence of DNA from saliva. This study was undertaken to determine the best decontamination strategy for the removal of DNA from laboratory consumables. We have identified autoclave and UV irradiation procedures that can eliminate nanogram quantities of contaminating DNA contained within cellular material. Autoclaving is more effective than UV irradiation because it can eliminate short fragments of contaminating DNA more effectively. Lengthy autoclave or UV irradiation treatments are required. Depending on bulb power, a UV crosslinker may take a minimum of 2h to achieve an effective dose for elimination of nanogram quantities of contaminating DNA (>7250mJ/cm(2)). Similarly autoclaving may also take 2h to eliminate similar quantities of contaminating DNA. For this study, we used dried saliva stains to determine the effective dose. Dried saliva stains were chosen because purified DNA as well as fresh saliva are less difficult to eradicate than dried stains and also because consumable contamination is more likely to be in the form of a collection of dry cells.

Mean Annual UV-B Irradiance

Data.gov (United States)

U.S. Environmental Protection Agency — Ultraviolet-B (UV-B) radiation is the most energetic part of sunlight reaching the Earth's surface (wavelength region is 280 to 315 nm), and it has been shown to...

The effect of UV and visible light irradiation on the development of microsclerotium of the fungus Macrophomina phaseolina

International Nuclear Information System (INIS)

Nagy, P.; Fischl, G.

2002-01-01

Macrophomina phaseolina is a poliphagus fungus, which is able to infect numerous host-plant (maize, sunflower, pepper) and causes large yield losses. Our in vitro experiments demonstrate, how different wavelength light irradiation influences the growth of mycelium and the formation of microsclerotium. The habit of cultures treated by blue light and UV radiation changed, the formed microsclerotia had a convenient sharpness for the data evaluation by CCD camera. The mycelium was degraded as a result of UV radiation

Changes in UV absorption of sunscreens after UV irradiation

Science.gov (United States)

Tarras-Wahlberg, N.; Stenhagen, G.; Larkö, O.; Rosén, A.; Wennberg, A.-M.; Wennerström, O.

2000-03-01

In the present investigation we have studied the change in the absorption spectrum of some photoactive organic species in sunscreens after UVA and UVB irradiation in a dose normally encountered during a full day in the sun. The absorbance of 2-ethylhexyl 4-methoxycinnamate was reduced significantly, while 3-(4-methylbenzyliden)camphor seemed to be rather stable. The benzophenones studied seemed to be relatively stable. In the case of 4-tert.butyl-4´-methoxy-dibenzoylmethane there was a rapid decrease in the UVA absorption leading to unsatisfactory protection in the UVA region. 4-Isopropyl-dibenzoylmethane also lost most of its UV protective capacity after irradiation with UVA. UVB seemed to have a minor effect on all the samples. The present study including gas chromatography and mass spectrometry analysis indicates that some of the photoactive organic species commonly used today in sunscreens are unstable following UV irradiation.

Influence of uvA on the erythematogenic and therapeutic effects of uvB irradiation in psoriasis; photoaugmentation effects

International Nuclear Information System (INIS)

Boer, J.; Schothorst, A.A.; Suurmond, D.

1981-01-01

The effect of repeated exposure to an additive dose of long ultraviolet (uvA) radiation on the erythemogenic and therapeutic effects of middle ultraviolet (uvB) irradiation was investigated in 8 patients with psoriasis. The surface of the backs of these patients was divided into 2 parts, 1 of which received only uvB irradiation 4 times a week and the other uvA + uvB. uvB was provided by Philips TL-12 lamps and uvA by glass-filtered Philips TL-09 lamps. uvA was held constantly at 10 J/cm2, whereas uvB alone were evaluated by 4 tests during the treatment to determine the minimal erythema dose (MED). Test I (at the start of the therapy) showed a photoaugmentative effect which was no longer apparent in Test III (third week). Test III showed a reversal of the ratios of the MEDs of the sites irradiated with the uvA + uvB and uvB (MED A + B/MED B). This is ascribed to the marked pigmentation which appeared after repeated irradiation with the uvA + uvB combination. Comparison showed for the improvement of the psoriasis no distinct differences between uvA + uvB irradiation and uvB alone, but the former had the cosmetic advantage of giving pleasing tan

Sulfonation of polyester fabrics by gaseous sulfur oxide activated by UV irradiation

International Nuclear Information System (INIS)

Kordoghli, Bessem; Khiari, Ramzi; Mhenni, Mohamed Farouk; Sakli, Faouzi; Belgacem, Mohamed Naceur

2012-01-01

Highlights: ► In this paper, an original technique was present to improve the hydrophilic properties of polyester fibres. ► The modification of PET fabric was carried out using gaseous sulfur trioxide activated by UV irradiations. ► We fully characterized the modified and untreated fabrics. - Abstract: This paper describes an original technique aiming to improve the hydrophilic properties of polyester fibres. In this method, the sulfonation of the aromatic rings is carried out using gaseous sulfur trioxide activated by UV irradiations. Thus, exposing the polyester textile fabric to the UVC light (wavelength around 254 nm) under a stream of sulfur trioxide leads to the fixation of -SO 3 H groups. The amounts of the fixed sulfonate groups depended on the reaction conditions. Evidence of grafting deduced from the measurements of hygroscopic properties was carried out by contact angle measurement, moisture regain as well as by measuring the rate of retention. SEM and FT-IR analysis, DSC and DTA/TGA thermograms showed that no significant modifications have occurred in the bulk of the treated PET fabrics.

Enhanced reactivation and mutagenesis of UV-irradiated adenovirus in normal human fibroblasts

International Nuclear Information System (INIS)

Bennett, C.B.; Rainbow, A.J.

1988-01-01

UV-enhanced reactivation (UVER) and UV-enhanced mutagenesis (UVEM) for two adenovirus temperature-sensitive mutants were examined following the infection of normal human fibroblasts. UV-irradiation of the virus alone resulted in dose-dependent increase in the UV-induced reversion frequency (RF) of viral progeny and a dose-dependent exponential decrease in progeny survival, when infecting non-irradiated cells. Analysis of the slopes of the UV-induced reversion curves suggested that 2.5 ± 0.3 and 2.4 ± 0.5 'hits' were required to produce a targeted reversion event among the viral progeny of Ad5ts36 and Ad5ts125 respectively. UV-irradiation of cells 24 h prior to infection resulted in a significant increase in progeny survival for UV-irradiated virus (UVER factor = 3.4 ± 0.8) concomitant with a significant increase in RF for UV-irradiated virus (targeted increase = 1.9 ± 0.3). The UV-induced RF per lethal hit to the virus was also significantly greater in UV-irradiated compared with non-irradiated cells. These results are consistent with the existence of a UV-inducible error-prone DNA repair mechanism in normal human cells. (author)

UV, visible and IR laser interaction with gelatine

International Nuclear Information System (INIS)

Oujja, M; Rebollar, E; Abrusci, C; Amo, A Del; Catalina, F; Castillejo, M

2007-01-01

In this work we investigate the effects on gelatine films of nanosecond pulsed laser irradiation at different laser wavelengths from the UV to the IR at 248, 266, 355, 532 and 1064 nm. We compared gelatines differing in gel strength values (Bloom 75 and 225) and in crosslinking degree. Formation of bubbles at the wavelengths in the UV (248 and 266 nm), melting and resolidification at 355 nm, and formation of craters by ablation in the VIS and IR (532 and 1064 nm) are the observed morphological changes. On the other hand, changes of the fluorescence behaviour of the films upon UV irradiation reveal chemical modifications of photolabile chromophores

[Investigation of multi-wavelength effect during the measurement of UV-enhanced film's emission spectrum].

Science.gov (United States)

Liu, Meng; Ni, Zheng-ji; Zhang, Da-wei; Huang, Yuan-shen; Zhuang, Song-lin

2009-09-01

The UV-responsive detector is a dual-use device for civilian and military after the laser and IR-responsive sensors. Typical image sensor coated with a layer of down-convert frequency thin film on it's photosurface to enhance UV response is the key technology of enhancing UV-response. The UV-enhanced thin film was made in the experimental laboratory using the Zn2SiO4:Mn phosphor by spin coating method. Two peaks at 520 and 560 nm respectively in the emission spectrum of the UV-enhanced film were found by SP1702 spectrograph when the excitation wavelength was 260 and 280 nm. The peaks were found in the process of experiment of measuring and counting the quantum efficiency of UV-enhanced thin film. But the light peaks at 520 and 560 nm are not the emission light peaks by the exciting light of 260 and 280 nm. The reason why the light at 520 and 560 nm is not the emission light was analyzed based on the measurement principle of grating spectrograph. The reasons for the multi-wavelength of light overlaps during the measurement of emission spectrum were also discussed. And the equipment used to separate the overlapped different wavelengths was designed, which will be used to resolve the problem of the overlap of multi-wavelength.

Studies on the mechanism of printing film-coated tablets containing titanium dioxide in the film by using UV laser irradiation.

Science.gov (United States)

Kato, Yoshiteru; Nakashima, Yasuhiko; Shino, Naoki; Sasaki, Koichi; Hosokawa, Akihiro; Ishihara, Hiroshi

2010-04-01

The purpose of this article is to study a detailed mechanism of printing when film-coated tablets were irradiated by UV laser at a wavelength of 355 nm. Hydroxypropylmethylcellulose (HPMC) film containing titanium dioxide (TiO(2)) and the film not containing TiO(2) and TiO(2) powder were lirradiated by the UV laser and estimated by the morphological observation by zoom stereo microscope, thermogravimetric analysis (TGA), total color difference (dE), X-ray powder diffraction (XRD), and dispersive Raman microscopy. In the case of the film containing TiO(2), the film showed a visible change in its color from white to gray by the UV laser irradiation. By zoom stereo microscope, it was found that the entire UV laser-irradiated area was not grayed uniformly, but many black particles, whose diameter was about 2 microm, were observed on the film. When TiO(2) powder was irradiated by the UV laser, a visible change in its color from white to gray was observed similar to the case of the film containing TiO(2). There were many black particles locally in the UV laser-treated TiO(2) powder by the morphological observation, and these black particles, agglomerates of the grayed oxygen-defected TiO(2), were associated with the visible change of the TiO(2). It was found that the film-coated tablets were printed utilizing the formation of the black particles by the agglomeration of the grayed oxygen-defected TiO(2) by the UV laser irradiation.

DNA metabolism in peripheral lymphocytes of UV-B wholebody irradiated men

International Nuclear Information System (INIS)

Klein, W.; Kocsis, F.; Altmann, H.

1983-02-01

Healthy probands were UV-B irradiated and different times after the treatment blood was taken and lymphocytes were isolated. Semiconservative DNA-synthesis was enhanced after 4 in vivo expositions. DNA repair replication in lymphocytes after in vitro UV-C damage was initially increased in UV-B wholebody irradiated people. With nucleoidsedimentation DNA strand breaks after in vivo UV-B irradiation were detected. (Author) [de

The role of free radicals and stress signalling in persistent genomic instability induced by long wavelength UV light

International Nuclear Information System (INIS)

Phillipson, R.; McMillan, T.J.

2003-01-01

Induction of persistent genomic instability has commonly been investigated with ionising radiation. It has been characterised as a decrease in plating efficiency, and an increase in chromosomal aberrations and mutation frequency in the progeny of cells that survive the initial irradiation. We now present data demonstrating the phenomenon following exposure to long-wavelength solar UV-A (320-400nm) radiation at environmentally relevant doses. Using the spontaneously immortalised human skin keratinocyte line, HaCaT, we observed a significant decrease in plating efficiency (77 +/- 2% of control), and increase in micronuclei (2.5 fold) and mutation frequency (2 fold), 7 days after the initial radiation insult. Modification of UV-A-induced instability by incubation with exogenous catalase implicated reactive oxygen species (ROS), in-particular hydrogen peroxide, in the production and/or maintenance of the phenomenon. Assessment of anti-oxidant enzymes revealed a significant increase in glutathione-s-transferase activity (158 +/- 4% of control) at day 7 in the irradiated cell population, which was inhibited by incubation with exogenous catalase (97 +/- 3%), providing further evidence for an ROS-mediated pathway. Furthermore, inhibition of UV-A-induced micronuclei at day 7 by the flavonoid-containing-protein inhibitor diphenyleneiodonium (DPI) indicates that the NADPH oxidase family of enzymes may be involved in this phenomenon. Measurement of superoxide production by the cytochrome c reduction assay revealed that the irradiated cell population produce 50% more superoxide than the unirradiated controls, and that incubation with DPI led to a preferential reduction in superoxide production in the UV-A treated population at day 7. Finally, NADPH oxidase activity is increased significantly over controls in UV-A-treated cells. These data demonstrate that oxidative stress, analogous to that produced by ionising radiation, induces persistent genomic instability through a

Covalent bindings in proteins following UV-C irradiation

International Nuclear Information System (INIS)

Diezel, W.; Meffert, H.; Soennichsen, N.; Reinicke, C.

1980-01-01

Following a UV-C irradiation of catalase cross-linked catalase subunits could be detected by sodium dodecylsulfate gel electrophoresis. The subunits of aldolase were not cross-linked. The origin of covalent bindings in the catalase molecule is suggested to be effected by a free radical chain reaction induced by the heme component of catalase after UV-C irradiation. (author)

UV irradiation improves the bond strength of resin cement to fiber posts.

Science.gov (United States)

Zhong, Bo; Zhang, Yong; Zhou, Jianfeng; Chen, Li; Li, Deli; Tan, Jianguo

2011-01-01

The purpose is to evaluate the effect of UV irradiation on the bond strength between epoxy-based glass fiber posts and resin cement. Twelve epoxy-based glass fiber posts were randomly divided into three groups. Group 1 (Cont.): No surface treatment. Group 2 (Low-UV): UV irradiation was conducted from a distance of 10 cm for 10 min. Group 3 (High-UV): UV irradiation was conducted from a distance of 1 cm for 3 min. A resin cement (CLEARFIL SA LUTING) was used for the post cementation to form resin slabs which contained fiber posts in the center. Microtensile bond strengths were tested and the mean bond strengths (MPa) were 18.81 for Cont. group, 23.65 for Low-UV group, 34.75 for High-UV group. UV irradiation had a significant effect on the bond strength (pUV irradiation demonstrates its capability to improve the bond strength between epoxy-based glass fiber posts and resin cement.

Photocatalytic properties of Au-deposited mesoporous SiO_2–TiO_2 photocatalyst under simultaneous irradiation of UV and visible light

International Nuclear Information System (INIS)

Okuno, T.; Kawamura, G.; Muto, H.; Matsuda, A.

2016-01-01

Mesoporous SiO_2 templates deposited TiO_2 nanocrystals are synthesized via a sol–gel route, and Au nanoparticles (NPs) are deposited in the tubular mesopores of the templates by a photodeposition method (Au/SiO_2–TiO_2). The photocatalytic characteristics of Au/SiO_2–TiO_2 are discussed with the action spectra of photoreactions of 2-propanol and methylene blue. Photocatalytic activities of SiO_2–TiO_2 under individual ultraviolet (UV) and visible (Vis) light illumination are enhanced by deposition of Au NPs. Furthermore, Au/SiO_2–TiO_2 shows higher photocatalytic activities under simultaneous irradiation of UV and Vis light compared to the activity under individual UV and Vis light irradiation. Since the photocatalytic activity under simultaneous irradiation is almost the same as the total activities under individual UV and Vis light irradiation, it is concluded that the electrons and the holes generated by lights of different wavelengths are efficiently used for photocatalysis without carrier recombination. - Graphical abstract: This graphic shows the possible charge behavior in Au/SiO_2–TiO_2 under independent light irradiation of ultraviolet and visible light irradiation. Both reactions under independent UV and Vis light irradiation occurred in parallel when Au/SiO_2–TiO_2 photocatalyst was illuminated UV and Vis light simultaneously, and then photocatalytic activity is improved by simultaneous irradiation. - Highlights: • Au nanoparticles were deposited in mesoporous SiO_2–TiO_2 by a photodeposition method. • Photocatalytic activity under UV and Vis light was enhanced by deposition of Au. • Photocatalytic activity of Au/SiO_2–TiO_2 was improved by simultaneous irradiation.

LED-based UV source for monitoring spectroradiometer properties

Science.gov (United States)

Sildoja, Meelis-Mait; Nevas, Saulius; Kouremeti, Natalia; Gröbner, Julian; Pape, Sven; Pendsa, Stefan; Sperfeld, Peter; Kemus, Fabian

2018-06-01

A compact and stable UV monitoring source based on state-of-the-art commercially available ultraviolet light emitting diodes (UV-LEDs) has been developed. It is designed to trace the radiometric stability—both responsivity and wavelength scale—of array spectroradiometers measuring direct solar irradiance in the wavelength range between 300 nm and 400 nm. The spectral irradiance stability of the UV-LED-based light source observed in the laboratory after seasoning (burning-in) the individual LEDs was better than 0.3% over a 12 h period of continuous operation. The integral irradiance measurements of the source over a period of several months, where the UV-LED source was not operated continuously between the measurements, showed stability within 0.3%. In-field measurements of the source with an array spectroradiometer indicated the stability of the source to be within the standard uncertainty of the spectroradiometer calibration, which was within 1% to 2%.

A cure for the blues: opsin duplication and subfunctionalization for short-wavelength sensitivity in jewel beetles (Coleoptera: Buprestidae).

Science.gov (United States)

Lord, Nathan P; Plimpton, Rebecca L; Sharkey, Camilla R; Suvorov, Anton; Lelito, Jonathan P; Willardson, Barry M; Bybee, Seth M

2016-05-18

Arthropods have received much attention as a model for studying opsin evolution in invertebrates. Yet, relatively few studies have investigated the diversity of opsin proteins that underlie spectral sensitivity of the visual pigments within the diverse beetles (Insecta: Coleoptera). Previous work has demonstrated that beetles appear to lack the short-wavelength-sensitive (SWS) opsin class that typically confers sensitivity to the "blue" region of the light spectrum. However, this is contrary to established physiological data in a number of Coleoptera. To explore potential adaptations at the molecular level that may compensate for the loss of the SWS opsin, we carried out an exploration of the opsin proteins within a group of beetles (Buprestidae) where short-wave sensitivity has been demonstrated. RNA-seq data were generated to identify opsin proteins from nine taxa comprising six buprestid species (including three male/female pairs) across four subfamilies. Structural analyses of recovered opsins were conducted and compared to opsin sequences in other insects across the main opsin classes-ultraviolet, short-wavelength, and long-wavelength. All nine buprestids were found to express two opsin copies in each of the ultraviolet and long-wavelength classes, contrary to the single copies recovered in all other molecular studies of adult beetle opsin expression. No SWS opsin class was recovered. Furthermore, the male Agrilus planipennis (emerald ash borer-EAB) expressed a third LWS opsin at low levels that is presumed to be a larval copy. Subsequent homology and structural analyses identified multiple amino acid substitutions in the UVS and LWS copies that could confer short-wavelength sensitivity. This work is the first to compare expressed opsin genes against known electrophysiological data that demonstrate multiple peak sensitivities in Coleoptera. We report the first instance of opsin duplication in adult beetles, which occurs in both the UVS and LWS opsin classes

Photoreactivation of UV-irradiated blue-green algae and algal virus LPP-1

Energy Technology Data Exchange (ETDEWEB)

Singh, P K [Central Rice Research Inst., Cuttack (India)

1975-01-01

Ultraviolet (UV) sensitivity and photoreactivation of blue-green algae Cylindrospermum sp., Plectonema boryanum, spores of Fischerella muscicola and algal virus (cyanophage) LPP-1 were studied. The survival value after UV irradiation of filaments of Cylindrospermum sp. and Virus LPP-1 showed exponential trend and these were comparatively sensitive towards UV than F. muscicola and P. boryanum. Photoreactivation of UV-induced damage occurred in black, blue, green, yellow, red and white light in Cylindrospermum sp., however only black, blue and white light were capable of photorepair of UV-induced damage in P. boryanum, spores of F. muscicola and virus LPP-1 in infected host alga. Pre-exposure to yellow and black light did not show photoprotection. The non-heterocystous and nitrogen fixation-less mutants of Cylindrospermum sp. were not induced by UV and their spontaneous mutation frequency was not affected after photoreactivation. The short trichome mutants of P. boryanum were more resistant towards UV. The occurrence of photoreactivation of UV-induced killing in wide range of light in Cylindrospermum sp. is the first report in organisms.

Surface properties of UV irradiated PC–TiO{sub 2} nanocomposite film

Energy Technology Data Exchange (ETDEWEB)

Jaleh, B., E-mail: bkjaleh@yahoo.com; Shahbazi, N.

2014-09-15

Highlights: • Production of PC–TiO{sub 2} nanocomposite films. • Fully characterization of PC–TiO{sub 2} nanocomposite films. • Influence of UV irradiation on surface properties and hardness of PC–TiO{sub 2} nanocomposite film. - Abstract: In this work, polycarbonate–TiO{sub 2} nanocomposite films were prepared with two different percentages. The structure of samples were studied by X-ray diffraction. Thermal stability of the nanocomposites was studied by thermogravimetric analysis (TGA). The polycarbonate and polycarbonate–TiO{sub 2} nanocomposite films were exposed by UV light at different irradiation times. The effects of UV irradiation on the surface properties of samples have been studied by different characterization techniques, viz. scanning electron microscopy (SEM), FTIR spectroscopy, X-ray photoelectron spectroscopy (XPS), contact angle measurement and Vickers microhardness tester. Hydrophilicity and surface energy of UV treated samples varied depending on UV irradiation time. TGA curves showed that nanocomposite films have higher resistance to thermal degradation compared to polycarbonate. XPS analysis shows that surface of samples become more oxidized due to UV irradiation. For nanocomposite film, the smallest contact angle was observed in association with the longest UV irradiation time. The contact angle significantly decreased from 90° to 12° after 15 h of UV irradiation. It is observed that the hardness of the nanocomposite films increases after UV irradiation.

UV-observations with a Brewer spectrophotometer at Hohenpeissenberg

Science.gov (United States)

Vandersee, Winfried; Koehler, U.

1994-01-01

Regular spectral UV-B measurements with a Brewer spectrophotometer have been performed at Hohenpeissenberg since 1990. Intercomparison of the Brewer instrument with other UV-B monitoring devices have shown agreement to within plus or minus 10 percent. Comparisons of UV-B spectra measured on fair weather days reveal the well known increasing influence of ozone on UV-B irradiance with decreasing wavelengths. The integral amplification factor the erythemal irradiance reaches values up to 2.8, which can be diminished by increasing turbidity. The influence of cirrus cloud on the UV-B is also shown.

Nitrogen Incorporation in CH4-N2 Photochemical Aerosol Produced by Far UV Irradiation

Science.gov (United States)

Trainer, Melissa G.; Jimenez, Jose L.; Yung, Yuk L.; Toon, Owen B.; Tolbert, Margaret A.

2012-01-01

Nitrile incorporation into Titan aerosol accompanying hydrocarbon chemistry is thought to be driven by extreme UV wavelengths (lambda irradiated gas. The aerosol mass greatly decreases when N2 is removed, indicating that N2 plays a major role in aerosol production. Because direct dissociation of N2 is highly improbable given the immeasurably low cross-section at the wavelengths studied, the chemical activation of N2 must occur via another pathway. Any chemical activation of N2 at wavelengths > 120 nm is presently unaccounted for in atmospheric photochemical models. We suggest that reaction with CH radicals produced from CH4 photolysis may provide a mechanism for incorporating N into the molecular structure of the aerosol. Further work is needed to understand the chemistry involved, as these processes may have significant implications for prebiotic chemistry on the early Earth and similar planets.

Wavelength dependence of biological damage induced by UV radiation on bacteria.

Science.gov (United States)

Santos, Ana L; Oliveira, Vanessa; Baptista, Inês; Henriques, Isabel; Gomes, Newton C M; Almeida, Adelaide; Correia, António; Cunha, Ângela

2013-01-01

The biological effects of UV radiation of different wavelengths (UVA, UVB and UVC) were assessed in nine bacterial isolates displaying different UV sensitivities. Biological effects (survival and activity) and molecular markers of oxidative stress [DNA strand breakage (DSB), generation of reactive oxygen species (ROS), oxidative damage to proteins and lipids, and the activity of antioxidant enzymes catalase and superoxide dismutase] were quantified and statistically analyzed in order to identify the major determinants of cell inactivation under the different spectral regions. Survival and activity followed a clear wavelength dependence, being highest under UVA and lowest under UVC. The generation of ROS, as well as protein and lipid oxidation, followed the same pattern. DNA damage (DSB) showed the inverse trend. Multiple stepwise regression analysis revealed that survival under UVA, UVB and UVC wavelengths was best explained by DSB, oxidative damage to lipids, and intracellular ROS levels, respectively.

Low-temperature formation of high-quality gate oxide by ultraviolet irradiation on spin-on-glass

International Nuclear Information System (INIS)

Usuda, R.; Uchida, K.; Nozaki, S.

2015-01-01

Although a UV cure was found to effectively convert a perhydropolysilazane (PHPS) spin-on-glass film into a dense SiO x film at low temperature, the electrical characteristics were never reported in order to recommend the use of PHPS as a gate-oxide material that can be formed at low temperature. We have formed a high-quality gate oxide by UV irradiation on the PHPS film, and obtained an interface midgap trap density of 3.4 × 10 11  cm −2 eV −1 by the UV wet oxidation and UV post-metallization annealing (PMA), at a temperature as low as 160 °C. In contrast to the UV irradiation using short-wavelength UV light, which is well known to enhance oxidation by the production of the excited states of oxygen, the UV irradiation was carried out using longer-wavelength UV light from a metal halide lamp. The UV irradiation during the wet oxidation of the PHPS film generates electron-hole pairs. The electrons ionize the H 2 O molecules and facilitate dissociation of the molecules into H and OH − . The OH − ions are highly reactive with Si and improve the stoichiometry of the oxide. The UV irradiation during the PMA excites the electrons from the accumulation layer, and the built-in electric field makes the electron injection into the oxide much easier. The electrons injected into the oxide recombine with the trapped holes, which have caused a large negative flat band voltage shift after the UV wet oxidation, and also ionize the H 2 O molecules. The ionization results in the electron stimulated dissociation of H 2 O molecules and the decreased interface trap density

Low-temperature formation of high-quality gate oxide by ultraviolet irradiation on spin-on-glass

Energy Technology Data Exchange (ETDEWEB)

Usuda, R.; Uchida, K.; Nozaki, S., E-mail: nozaki@ee.uec.ac.jp [Graduate School of Informatics and Engineering, The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu-shi, Tokyo 182-1515 (Japan)

2015-11-02

Although a UV cure was found to effectively convert a perhydropolysilazane (PHPS) spin-on-glass film into a dense SiO{sub x} film at low temperature, the electrical characteristics were never reported in order to recommend the use of PHPS as a gate-oxide material that can be formed at low temperature. We have formed a high-quality gate oxide by UV irradiation on the PHPS film, and obtained an interface midgap trap density of 3.4 × 10{sup 11 }cm{sup −2} eV{sup −1} by the UV wet oxidation and UV post-metallization annealing (PMA), at a temperature as low as 160 °C. In contrast to the UV irradiation using short-wavelength UV light, which is well known to enhance oxidation by the production of the excited states of oxygen, the UV irradiation was carried out using longer-wavelength UV light from a metal halide lamp. The UV irradiation during the wet oxidation of the PHPS film generates electron-hole pairs. The electrons ionize the H{sub 2}O molecules and facilitate dissociation of the molecules into H and OH{sup −}. The OH{sup −} ions are highly reactive with Si and improve the stoichiometry of the oxide. The UV irradiation during the PMA excites the electrons from the accumulation layer, and the built-in electric field makes the electron injection into the oxide much easier. The electrons injected into the oxide recombine with the trapped holes, which have caused a large negative flat band voltage shift after the UV wet oxidation, and also ionize the H{sub 2}O molecules. The ionization results in the electron stimulated dissociation of H{sub 2}O molecules and the decreased interface trap density.

The UV-A and visible solar irradiance spectrum: inter-comparison of absolutely calibrated, spectrally medium resolution solar irradiance spectra from balloon- and satellite-borne measurements

Directory of Open Access Journals (Sweden)

W. Gurlit

2005-01-01

Full Text Available Within the framework of the ENVISAT/-SCIAMACHY satellite validation, solar irradiance spectra are absolutely measured at moderate resolution in the UV/visible spectral range (in the UV from 316.7-418 nm and the visible from 400-652 nm at a full width half maximum resolution of 0.55 nm and 1.48 nm, respectively from aboard the azimuth-controlled LPMA/DOAS balloon gondola at around 32 km balloon float altitude. After accounting for the atmospheric extinction due to Rayleigh scattering and gaseous absorption (O3 and NO2, the measured solar spectra are compared with previous observations. Our solar irradiance spectrum perfectly agrees within +0.03% with the re-calibrated Kurucz et al. (1984 solar spectrum (Fontenla et al., 1999, called MODTRAN 3.7 in the visible spectral range (415-650 nm, but it is +2.1% larger in the (370-415 nm wavelength interval, and -4% smaller in the UV-A spectral range (316.7-370 nm, when the Kurucz spectrum is convolved to the spectral resolution of our instrument. Similar comparisons of the SOLSPEC (Thuillier et al., 1997, 1998a, b and SORCE/SIM (Harder et al., 2000 solar spectra with MODTRAN 3.7 confirms our findings with the values being -0.5%, +2%, and -1.4% for SOLSPEC -0.33%, -0.47%, and -6.2% for SORCE/SIM, respectively. Comparison of the SCIAMACHY solar spectrum from channels 1 to 4 (- re-calibrated by the University of Bremen - with MODTRAN 3.7 indicates an agreement within -0.4% in the visible spectral range (415-585 nm, -1.6% within the 370-415 nm, and -5.7% within 325-370 nm wavelength interval, in agreement with the results of the other sensors. In agreement with findings of Skupin et al. (2002 our study emphasizes that the present ESA SCIAMACHY level 1 calibration is systematically +15% larger in the considered wavelength intervals when compared to all available other solar irradiance measurements.

Sulfonation of polyester fabrics by gaseous sulfur oxide activated by UV irradiation

Energy Technology Data Exchange (ETDEWEB)

Kordoghli, Bessem [Laboratory of Applied Chemical and Environment (UR-CAE) - University of Monastir (Tunisia); Textile Research Laboratory (LRT) - ISET Kasr Hellal, University of Monastir (Tunisia); Khiari, Ramzi, E-mail: khiari_ramzi2000@yahoo.fr [Laboratory of Applied Chemical and Environment (UR-CAE) - University of Monastir (Tunisia); LGP2 - Laboratory of Pulp and Paper Science, 461, Rue de la Papeterie - BP 65, 38402 Saint Martin d' Heres Cedex (France); Mhenni, Mohamed Farouk [Laboratory of Applied Chemical and Environment (UR-CAE) - University of Monastir (Tunisia); Sakli, Faouzi [Textile Research Laboratory (LRT) - ISET Kasr Hellal, University of Monastir (Tunisia); Belgacem, Mohamed Naceur [LGP2 - Laboratory of Pulp and Paper Science, 461, Rue de la Papeterie - BP 65, 38402 Saint Martin d' Heres Cedex (France)

2012-10-01

Highlights: Black-Right-Pointing-Pointer In this paper, an original technique was present to improve the hydrophilic properties of polyester fibres. Black-Right-Pointing-Pointer The modification of PET fabric was carried out using gaseous sulfur trioxide activated by UV irradiations. Black-Right-Pointing-Pointer We fully characterized the modified and untreated fabrics. - Abstract: This paper describes an original technique aiming to improve the hydrophilic properties of polyester fibres. In this method, the sulfonation of the aromatic rings is carried out using gaseous sulfur trioxide activated by UV irradiations. Thus, exposing the polyester textile fabric to the UVC light (wavelength around 254 nm) under a stream of sulfur trioxide leads to the fixation of -SO{sub 3}H groups. The amounts of the fixed sulfonate groups depended on the reaction conditions. Evidence of grafting deduced from the measurements of hygroscopic properties was carried out by contact angle measurement, moisture regain as well as by measuring the rate of retention. SEM and FT-IR analysis, DSC and DTA/TGA thermograms showed that no significant modifications have occurred in the bulk of the treated PET fabrics.

Effect of artificial UV irradiation on spore content of stall air and fattening pig breeding

International Nuclear Information System (INIS)

Kalich, J.; Blendl, H.M.

1978-01-01

The influence of a continuous UV irradiation (emitter NN 33/89 original Hanau) during the fattening periods primarily in the bactericide region of 253.7 nm of various intensities on the spore content of air, on the state of health and on the fattening breeding of pigs was tested in two fattening procedures. The high spore number per m 3 air of over 700 000 upon occupying the stall in the first fattening procedure was reduced by 90.5% to about 70 000 after 1 week of UV irradiation, and in the second procedure, from 111 500 to 16 000, i.e. a reduction of 85.5%. The spore content of the stall air then exhibited large deviations reducing and increasing. The same deviations were recorded for dust content. There was no absolute correlation between dust and spore content of the air until the 11th week after starting UV irradiation in either test. The spore content sank in the reference stalls also without UV irradiation, by 29.9% in the first fattening procedure 1 week after occupying the stall and even by 75% in the second procedure. The spore content of the air in the reference stalls also then exhibited deviations sinking and rising as in the test stalls with UV irradiation. Here too, there was no correlation between dust and spore content of the air. The spore content in the air was 2 to 7 times higher in the reference stalls than in the test stalls. One may conclude from the tests that the promoting irradiation strength is between 15 and 20 μW/cm 2 and that short-term stool production in danish stalling, 60 μW/cm 2 are not harmful. Air disinfection with UV irradiation, can only be part of the total hygiene measures taken in veterinary medicine and may only be considered as an important link in the chain of the health promoting and increased efficient hygiene measures in the intensification of aggriculturally useful animals. (orig./AJ) [de

Impact of Room Location on UV-C Irradiance and UV-C Dosage and Antimicrobial Effect Delivered by a Mobile UV-C Light Device.

Science.gov (United States)

Boyce, John M; Farrel, Patricia A; Towle, Dana; Fekieta, Renee; Aniskiewicz, Michael

2016-06-01

OBJECTIVE To evaluate ultraviolet C (UV-C) irradiance, UV-C dosage, and antimicrobial effect achieved by a mobile continuous UV-C device. DESIGN Prospective observational study. METHODS We used 6 UV light sensors to determine UV-C irradiance (W/cm2) and UV-C dosage (µWsec/cm2) at various distances from and orientations relative to the UV-C device during 5-minute and 15-minute cycles in an ICU room and a surgical ward room. In both rooms, stainless-steel disks inoculated with methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), and Clostridium difficile spores were placed next to sensors, and UV-C dosages and log10 reductions of target organisms achieved during 5-minute and 15-minute cycles were determined. Mean irradiance and dosage readings were compared using ANOVA. RESULTS Mean UV-C irradiance was nearly 1.0E-03 W/cm2 in direct sight at a distance of 1.3 m (4 ft) from the device but was 1.12E-05 W/cm2 on a horizontal surface in a shaded area 3.3 m (10 ft) from the device (P4 to 1-3 for MRSA, >4 to 1-2 for VRE and >4 to 0 log10 for C. difficile spores, depending on the distance from, and orientation relative to, the device with 5-minute and 15-minute cycles. CONCLUSION UV-C irradiance, dosage, and antimicrobial effect received from a mobile UV-C device varied substantially based on location in a room relative to the UV-C device. Infect Control Hosp Epidemiol 2016;37:667-672.

Presence of UV-endonuclease sensitive sites in daughter DNA of UV-irradiated mammalian cells

International Nuclear Information System (INIS)

D'Ambrosio, S.; Setlow, R.B.

1978-02-01

Asynchronous Chinese hamster cells were irradiated with 10 Jm -2 uv radiation and 0.25 to 4 hours later pulse-labeled with [ 3 H]thymidine. Cells synchronized by shaking off mitotic and G 1 cells were irradiated in either the G 1 -phase or S-phase of the cell cycle and pulse-labeled with [ 3 H]thymidine in the S-phase. After a 12 to 14 hour chase in unlabeled medium, the DNA was extracted, incubated with Micrococcus luteus uv-endonuclease and sedimented in alkaline sucrose. The number of endonuclease sensitive sites decreased as the time between uv irradiation and pulse-labeling of daughter DNA increased. Further, there were significantly less endonuclease sensitive sites in the daughter DNA from cells irradiated in the G 1 -phase than in the S-phase. These data indicate that very few, if any, dimers are transferred from parental DNA to daughter DNA and that the dimers detected in daughter DNA may be due to the irradiation of replicating daughter DNA before labeling

An EPR study on wastewater disinfection by peracetic acid, hydrogen peroxide and UV irradiation.

Science.gov (United States)

Bianchini, Roberto; Calucci, Lucia; Caretti, Cecilia; Lubello, Claudio; Pinzino, Calogero; Piscicelli, Michela

2002-09-01

EPR spectroscopy was applied to obtain qualitative and quantitative information on the radicals produced in disinfection processes of wastewater for agricultural reuse. The DEPMPO spin trap was employed to detect hydroxyl and carbon-centered short living radicals in two different peracetic acid solutions and a hydrogen peroxide solution used for water disinfection either in the absence or in the presence of UV-C irradiation. Moreover, three different kinds of water (wastewater, demineralized water, distilled water) were analysed in order to assess the contribution of Fenton reactions to the radical production. The spectroscopic results were discussed in relation to the efficiency of the different oxidizing agents and UV irradiation in wastewater disinfection evaluated as Escherichia Coli, Faecal and Total Coliforms inactivation.

Color tuning of photonic gel films by UV irradiation

Science.gov (United States)

Shin, Sung Eui; Kim, Su Young; Shin, Dong Myung

2010-02-01

Block copolymers have drawn increasing attention for fabricating functional nanomaterials due to their properties of self-assembly. In particular, photonic crystals hold promise for multiple optical applications. We prepared 1D photonic crystals with polystyrene-b-poly(2-vinyl pyridine) (PS-b-P2VP) lamellar films which is hydrophobic block-hydrophilic polyelectrolyte block polymer of 57 kg /mol-b-57 kg/mol. The lamellar stacks, which are alternating layers of hydrophilic and hydrophobic moiety of PS-b-P2VP, are obtained by exposing the spin coated film under chloroform vapor. The band gaps of the lamellar films interestingly varied after immersion into the quaternizing solvents containing 5wt% of iodomethane solubilized in n-hexane. We demonstrate about the influence of UV light on those photonic gel films. To study of different properties of films, UV-visible absorption spectra were measured as a different UV irradiation time at swollen films with distilled water. The UV-visible maximum absorption spectra shifted by UV irradiation time. Dependent on the time of UV irradiations, we can change the photonic band gap.

Patterning of nanoparticulate transparent conductive ITO films using UV light irradiation and UV laser beam writing

International Nuclear Information System (INIS)

Solieman, A.; Moharram, A.H.; Aegerter, M.A.

2010-01-01

Indium tin oxide (ITO) thin film is one of the most widely used as transparent conductive electrodes in all forms of flat panel display (FPD) and microelectronic devices. Suspension of already crystalline conductive ITO nanoparticles fully dispersed in alcohol was spun, after modifying with coupling agent, on glass substrates. The low cost, simple and versatile traditional photolithography process without complication of the photoresist layer was used for patterning ITO films. Using of UV light irradiation through mask and direct UV laser beam writing resulted in an accurate linear, sharp edge and very smooth patterns. Irradiated ITO film showed a high transparency (∼85%) in the visible region. The electrical sheet resistance decrease with increasing time of exposure to UV light and UV laser. Only 5 min UV light irradiation is enough to decrease the electrical sheet resistance down to 5 kΩ□.

Mutagenesis and reparation processes in the methylotrophic bacterium Pseudomonas methanolica after UV irradiation

International Nuclear Information System (INIS)

Naumov, G.N.; Bokhan, I.K.; Multykh, I.G.

1986-01-01

High resistance of cells of methylotrophic bacterium Pseudomonas methanolica to bactericidal and mutagenous effects of ultraviolet irradiation is shown as well as activity of reparation processes after UV irradiation. The presence of low photoreactivating activity in P. methanolica is shown as well. Observed recovery in innutritious medium and decrease of irradiated cells survival rates under effect of reparation inhibitors (coffeine and acriflavine) testify to activity of excision reparation and, perhaps, recombination branch of postreplicative reparation. No manifestation of inducible reparation system is discovered. It is concluded that increased resistance of P. methanolica cells to bactericidal and mutagenous effects of short-wave ultraviolet radiation is related to activity of exact reparation systems

Coumarin-BODIPY hybrids by heteroatom linkage: versatile, tunable and photostable dye lasers for UV irradiation.

Science.gov (United States)

Esnal, I; Duran-Sampedro, G; Agarrabeitia, A R; Bañuelos, J; García-Moreno, I; Macías, M A; Peña-Cabrera, E; López-Arbeloa, I; de la Moya, S; Ortiz, M J

2015-03-28

Linking amino and hydroxycoumarins to BODIPYs through the amino or hydroxyl group lets the easy construction of unprecedented photostable coumarin-BODIPY hybrids with broadened and enhanced absorption in the UV spectral region, and outstanding wavelength-tunable laser action within the green-to-red spectral region (∼520-680 nm). These laser dyes allow the generation of a valuable tunable UV (∼260-350 nm) laser source by frequency doubling, which is essential to study accurately the photochemistry of biological molecules under solar irradiation. The tunability is achieved by selecting the substitution pattern of the hybrid. Key factors are the linking heteroatom (nitrogen vs. oxygen), the number of coumarin units joined to the BODIPY framework and the involved linking positions.

Choice of Eye-Safe Radiation Wavelength in UV and Near IR Spectral Bands for Remote Sensing

Directory of Open Access Journals (Sweden)

M. L. Belov

2016-01-01

Full Text Available The introduction of laser remote sensing systems carries a particular risk to the human’s sense of vision. A structure of the eye, and especially the retina, is the main critical organ as related to the laser radiation.The work uses the optical models of the atmosphere, correctly working in both the UV and the near-IR band, to select the eye-safe radiation wavelengths in the UV (0.355 m and near-IR (~ 1.54 and ~ 2 m spectral bands from the point of view of recorded lidar signal value to fulfill the tasks of laser sensing the natural formations and laser aerosol sensing in the atmosphere.It is shown that the remote sensing lasers with appropriate characteristics can be selected both in the UV band (at a wavelength of 0.355 μm and in the near-IR band (at wavelengths of 1.54 ~ or ~ 2 μm.Molecular scattering has its maximum (for the selected wavelength at a wavelength of 0.355 μm in the UV band, and the minimum at the wavelengths of 1.54 and 2.09 μm in the near -IR band. The main contribution to the molecular absorption at a wavelength of 0.355 μm is made by ozone. In the near-IR spectral band the radiation is absorbed due to water vapor and carbon dioxide.Calculations show that the total effect of the molecular absorption and scattering has no influence on radiation transmission for both the wavelength of 0.355 μm in the UV band, and the wavelengths of 1.54 and 2.09 μm in the near-IR band for sensing trails ~ 1 km.One of the main factors of laser radiation attenuation in the Earth's atmosphere is radiation scattering by aerosol particles.The results of calculations at wavelengths of 0.355 μm, 1.54 μm and 2.09 μm for the several models of the atmosphere show that a choice of the most effective (in terms of the recorded signal of lidar and eye-safe radiation wavelength depends strongly on the task of sensing.To fulfill the task of laser sensing the natural formations, among the eye-safe wavelengths there is one significantly advantageous

Evaluating the effects of UV-B and UV-A irradiances on plant pigments, photosynthesis and growth in Glycine max L

International Nuclear Information System (INIS)

Middleton, E.H.M.

1993-01-01

Increasing penetration of UV-B radiation to the earth's surface resulting from stratospheric ozone depletion is an important environmental concern, but plant response to UV-B irradiation has been difficult to assess. The UV-A irradiance has not been specifically measured or controlled previously. The experimental UV-A was controlled in a series of three glasshouse experiments conducted under high photosynthetic photon flux (midday PPF ≥ 1200 μmol m -2 s -1 ). Low (LT) and High (HT) daily UV-B BE irradiances (10.7; 14.1 kJ m -2 ) were utilized in two experiments, whereas treatments with different UV-B BE :UV-A ratios ( BE :UV-A ratios

UV irradiation assisted growth of ZnO nanowires on optical fiber surface

Energy Technology Data Exchange (ETDEWEB)

Gong, Bo; Shi, Tielin; Liao, Guanglan; Li, Xiaoping; Huang, Jie; Zhou, Temgyuan; Tang, Zirong, E-mail: zirong@mail.hust.edu.cn

2017-06-01

Highlights: • A new fabrication process combined a hydrothermal process with UV irradiation from optical fiber is developed. • The growth of ZnO nanowires is efficient in the utilization of UV light. • A novel hybrid structure which integrates ZnO nanowires on optical fiber surface is synthesized. • The UV assisted growth of ZnO nanowires shows preferred orientation and better quality. • A mechanism of growing ZnO nanowires under UV irradiation is proposed. - Abstract: In this paper, a novel approach was developed for the enhanced growth of ZnO nanowires on optical fiber surface. The method combined a hydrothermal process with the efficient UV irradiation from the fiber core, and the effects of UV irradiation on the growth behavior of ZnO nanowires were investigated. The results show that UV irradiation had great effects on the preferred growth orientation and the quality of the ZnO nanowires. The crystallization velocity along the c-axis would increase rapidly with the increase of the irradiation power, while the growth process in the lateral direction was marginally affected by the irradiation. The structure of ZnO nanowires also shows less oxygen vacancy with UV irradiation of higher power. The developed approach is applicable for the efficient growth of nanowires on the fiber surface, and the ZnO nanowires/optical fiber hybrid structures have great potentials for a wide variety of applications such as optical fiber sensors and probes.

Effect of UV-irradiation on rotavirus

International Nuclear Information System (INIS)

Smirnov, Y.A.; Kapitulets, S.P.; Kaverin, N.V.; Amitina, N.N.; Ginevskaya, V.A.

1991-01-01

The effect of UV-irradiation on the infectivity of the SAll rotavirus was examined. The time behavior of the inactivation of infectivity generally exhibited the one-hit pattern. The effect was studied with respect to two phenomena, viz. the RNA-protein linkage and the formation of uracil dimers. To determine the number of the latter, purified 3 H-uridine-labelled rotavirus was exposed to UV radiation, and the RNA was extracted and analyzed by paper chromatography in the ascending mode. The formation of photodimers was found to be an important mechanism in the rotavirus inactivation on conventional irradiation, whereas RNA-protein linkages were observed on the application of high doses only. (author). 3 figs., 10 refs

Action spectrum and mechanisms of UV radiation-induced injury in lupus erythematosus

International Nuclear Information System (INIS)

Kochevar, I.E.

1985-01-01

Photosensitivity associated with lupus erythematosus (LE) is well established. The photobiologic basis for this abnormal response to ultraviolet radiation, however, has not been determined. This paper summarizes the criteria for elucidating possible photobiologic mechanisms and reviews the literature relevant to the mechanism of photosensitivity in LE. In patients with LE, photosensitivity to wavelengths shorter than 320 nm has been demonstrated; wavelengths longer than 320 nm have not been adequately evaluated. DNA is a possible chromophore for photosensitivity below 320 nm. UV irradiation of skin produces thymine photodimers in DNA. UV-irradiated DNA is more antigenic than native DNA and the antigenicity of UV-irradiated DNA has been proposed, but not proven, to be involved in the development of clinical lesions. UV irradiation of mice previously injected with anti-UV-DNA antibodies produces Ig deposition and complement fixation that appears to be similar to the changes seen in lupus lesions. Antibodies to UV-irradiated DNA occur in the serum of LE patients although a correlation between antibody titers and photosensitivity was not observed. Defective repair of UV-induced DNA damage does not appear to be a mechanism for the photosensitivity in LE. Other mechanisms must also be considered. The chromophore for photosensitivity induced by wavelengths longer than 320 nm has not been investigated in vivo. In vitro studies indicate that 360-400 nm radiation activates a photosensitizing compound in the lymphocytes and serum of LE patients and causes chromosomal aberrations and cell death. The mechanism appears to involve superoxide anion

EPR and UV spectrometry investigation of sucrose irradiated with carbon particles

International Nuclear Information System (INIS)

Karakirova, Yordanka; Yordanov, Nicola D.

2010-01-01

Solid state/EPR (SS/EPR) dosimeters of carbon ions irradiated sucrose are studied with EPR, and their water solutions - with UV spectroscopy. Doses between 20 and 200 Gy are used with linear energy transfer (LET) values for carbon ions of 63, 77, 96 and 230 keV μm -1 . After irradiation all samples show typical for irradiated sucrose EPR and UV spectra. The obtained data are compared with those previously reported for nitrogen particles and gamma rays irradiated sucrose. The identical shape of both the EPR and UV spectra of irradiated with various type radiation samples suggests that generated free radicals are not influenced by the nature of radiation. The lack of difference in the line width of the separate lines or the whole EPR spectrum, obtained for gamma and heavy particles irradiation, suggests negligible spin-spin interaction among the radiation-generated free radicals in the samples. The linear dependence of the EPR response on the absorbed dose radiation is found to be higher when generated by gamma rays, than by the same absorbed dose of heavy particles. In addition, the EPR response for carbon ions is higher than that for nitrogen ions. Water solutions of irradiated sucrose exhibit UV spectrum with absorption maximum at 267 nm, attributed to the recombination products of free radicals. The UV band intensity depends on the absorbed dose radiation. The UV spectra obtained for carbon, nitrogen and gamma rays irradiated sucrose are also compared.

Assays of residual antibiotics after treatment of γ-ray and UV irradiation

International Nuclear Information System (INIS)

Shin, Ji Hye; Nam, Ji Hyun; Lee, Dong Hun; Yu, Seung Ho; Lee, Myun Joo

2010-01-01

The pollution of antibiotics is a major cause of spreading antibiotics resistant bacteria in the environment. Applications of ozonation, UV, and γ-ray irradiations have been introduced to remove antibiotics in the effluents from wastewater treatment system. In this study, we compared the chemical (HPLC) and biological (antimicrobial susceptibility test, AMS) assays in measuring of the concentrations of residual antibiotics after γ-ray and UV irradiation. Most samples were degraded by γ-ray irradiation (1 ∼ 2 kGy). However, lincomycin and tetracycline were not degraded by UV irradiation. The concentration of residual antibiotics, that was treated with γ-ray and UV irradiation, measuring by bioassay was similar to HPLC. The concentrations of γ-ray irradiated cephradine measured by AMS test were 2 times higher than of HPLC assay, indicating AMS test is more sensitive than HPLC assay. These results indicate that γ-ray irradiation technique is more useful than UV irradiation, and biological assay is more useful to detect the antibiotics and toxic intermediates in antibiotics degradation

Controlled UV-C light-induced fusion of thiol-passivated gold nanoparticles.

Science.gov (United States)

Pocoví-Martínez, Salvador; Parreño-Romero, Miriam; Agouram, Said; Pérez-Prieto, Julia

2011-05-03

Thiol-passivated gold nanoparticles (AuNPs) of a relatively small size, either decorated with chromophoric groups, such as a phthalimide (Au@PH) and benzophenone (Au@BP), or capped with octadecanethiol (Au@ODCN) have been synthesized and characterized by NMR and UV-vis spectroscopy as well as transmission electron microscopy (TEM). These NPs were irradiated in chloroform at different UV-wavelengths using either a nanosecond laser (266 and 355 nm, ca. 12 mJ/pulse, 10 ns pulse) or conventional lamps (300 nm UV-vis spectroscopy, as well as by TEM. Laser irradiation at 355 nm led to NP aggregation and precipitation, while the NPs were photostable under UV-A lamp illumination. Remarkably, laser excitation at 266 nm induced a fast (minutes time-scale) increase in the size of the NPs, producing huge spherical nanocrystals, while lamp-irradiation at UV-C wavelengths brought about nanonetworks of partially fused NPs with a larger diameter than the native NPs.

Investigation of the mechanisms by which UV irradiation activates the tyrosinase gene

International Nuclear Information System (INIS)

Bao, Y.

2000-04-01

Tyrosinase, tyrosinase related protein-1 (TRP-1) and tyrosinase related protein-2 (TRP-2) are the enzymes involved in melanin pigment synthesis. They are expressed specifically in melanocytic cells. UV irradiation is the major physiological stimulant of melanogenesis. Tyrosinase is the rate-limiting enzyme in melanin synthesis and its activity is regulated by UV irradiation in melanocytes. The molecular mechanism underlying the activation of tyrosinase by UV is still not clear. In this thesis, the effects of UV irradiation on tyrosinase, TRP-1 and TRP-2 gene expression in mouse B16 melanoma cells were studied as well as the effects of UV irradiation on the activity of the tyrosinase promoter in mouse, and human melanoma cells. UV irradiation caused an increase in tyrosinase mRNA level, without change in either TRP-1 or TRP-2 mRNA levels, as determined by Northern blot analysis. In order to determine whether UV- induced increase of tyrosinase mRNA expression involved modulation of tyrosinase promoter activity, transient transfection approaches involving a series of constructs containing either chloramphenicol acetyl transferase (CAT) or luciferase reporter genes linked to different lengths of the tyrosinase gene- promoter were used. UV irradiation specifically induced CAT gene expression from both the mouse and the human tyrosinase promoters, suggesting that UV irradiation induced the transcription of the tyrosinase gene. These observations indicated that the promoter region between -250 and -150 bp of the human tyrosinase promoter may contain important cis-regulatory elements involved in the UV response. To localise the cis-regulatory elements responsible for the UV response of the tyrosinase promoter, the 100-bp between -250 bp and -150 bp of the tyrosinase promoter was inserted upstream of a CAT reporter. It was shown that transcription from the 100-bp promoter fragment was activated by UV irradiation. Mutations of a potential cAMP response element (CRE) motif

Short wavelength FELs using the SLAC linac

International Nuclear Information System (INIS)

Winick, H.; Bane, K.; Boyce, R.

1993-08-01

Recent technological developments have opened the possibility to construct a device which we call a Linac Coherent Light Source (LCLS); a fourth generation light source, with brightness, coherence, and peak power far exceeding other sources. Operating on the principle of the free electron laser (FEL), the LCLS would extend the range of FEL operation to much aborter wavelength than the 240 mn that has so far been reached. We report the results of studies of the use of the SLAC linac to drive an LCLS at wavelengths from about 3-100 nm initially and possibly even shorter wavelengths in the future. Lasing would be achieved in a single pass of a low emittance, high peak current, high energy electron beam through a long undulator. Most present FELs use an optical cavity to build up the intensity of the light to achieve lasing action in a low gain oscillator configuration. By eliminating the optical cavity, which is difficult to make at short wavelengths, laser action can be extended to shorter wavelengths by Self-Amplified-Spontaneous-Emission (SASE), or by harmonic generation from a longer wavelength seed laser. Short wavelength, single pass lasers have been extensively studied at several laboratories and at recent workshops

Wavelength shifting films on multianode PMTs with UV-extended window for the CBM RICH detector

Energy Technology Data Exchange (ETDEWEB)

Adamczewski-Musch, J. [GSI Darmstadt (Germany); Becker, K.-H. [University Wuppertal (Germany); Belogurov, S. [ITEP Moscow (Russian Federation); Boldyreva, N. [PNPI Gatchina (Russian Federation); Chernogorov, A. [ITEP Moscow (Russian Federation); Deveaux, C. [University Gießen (Germany); Dobyrn, V. [PNPI Gatchina (Russian Federation); Dürr, M., E-mail: Michael.Duerr@ap.physik.uni-giessen.de [University Gießen (Germany); Eom, J. [Pusan National University (Korea, Republic of); Eschke, J. [GSI Darmstadt (Germany); Höhne, C. [University Gießen (Germany); Kampert, K.-H. [University Wuppertal (Germany); Kleipa, V. [GSI Darmstadt (Germany); Kochenda, L. [PNPI Gatchina (Russian Federation); Kolb, B. [GSI Darmstadt (Germany); Kopfer, J., E-mail: Jan.Kopfer@uni-wuppertal.de [University Wuppertal (Germany); Kravtsov, P. [PNPI Gatchina (Russian Federation); Lebedev, S.; Lebedeva, E. [University Gießen (Germany); Leonova, E. [PNPI Gatchina (Russian Federation); and others

2014-12-01

Electron identification in the Compressed Baryonic Matter (CBM) experiment at the future Facility for Antiproton and Ion Research (FAIR) will be performed using a gaseous RICH detector. Due to the UV transparency of the CO{sub 2} radiator, a high photon detection efficiency of the PMTs in use at small wavelengths is favourable. The use of wavelength shifting (WLS) films aims at increasing the integral quantum efficiency of the photon sensors. WLS films absorb UV photons and re-emit photons at longer wavelengths where the quantum efficiency of common photocathodes is higher. As photon sensors, multianode PMTs (MAPMTs) with bialkali or superbialkali photocathodes and UV-extended windows are envisaged. We present quantum efficiency measurements with and without WLS coating for different types of MAPMTs as well as results from a beam test at the CERN PS. An increased photon yield was observed when using WLS films. In addition, we discuss the effect of WLS films on the spatial resolution of MAPMTs. - Highlights: • Wavelength shifting (WLS) films were applied on MAPMTs with UV-window. • WLS films considerably enhance MAPMT quantum efficiency in the UV range. • In-beam tests with a RICH detector show an enhanced total photon yield by approx. 20%. • Yield enhancement depends on the MAPMT window and photocathode materials. • No significant effect of WLS films on ring sharpness was detected.

UV-induced cross-linking of abscisic acid to binding proteins

International Nuclear Information System (INIS)

Cornelussen, M.H.M.; Karssen, C.M.; Loon, L.C. van

1995-01-01

Conditions for UV-induced cross-linking of abscisic acid (ABA) through its enone chromophore to binding proteins were evaluated. The effects of a UV-light band between 260 and 530 nm on both unconjugated and protein-conjugated ABA, as well as on anti-ABA antibodies as models of ABA-binding proteins were determined. UV irradiation caused both isomerization and photolysis of ABA, but increasing the lower irradiation boundary to 345 nm strongly reduced photolysis and largely prevented isomerization. When conjugated to alkaline phosphatase (AP), ABA remained stable when using either a 320 or a 345 nm filter. At these wavelengths both binding of ABA to antibodies as well as AP enzymatic activity were maintained. UV-induced cross-linking of monoclonal anti-ABA antibodies to immobilized ABA was analysed by immunoassays. Optimal cross-linking was achieved after a 5 min irradiation period at 0°, using a long pass, cut-on filter to quench wavelengths below 290 nm. This cross-linking faithfully reflected cognate binding activity. (author)

UV irradiation promotes the accumulation of triglyceride in Lipomyces lipofer

International Nuclear Information System (INIS)

Konno, A.; Suzuki, Y.; Ogawa, T.; Taniuchi, T.

2009-01-01

Yeasts of the genus Lipomyces are known as fat yeasts, and they store large amounts of lipids. Because the major lipid produced by Lipomyces is triglyceride, which can be used as a food and energy resource, the control of lipid production by Lipomyces sp. is an important issue. Here we report the effects of UV irradiation on lipid production in Lipomyces lipofer cells. UV irradiation (315-400 nm) led to a 4-fold increase in the amount of triglyceride per cell. We discovered a novel phenomenon, that UV irradiation promotes triglyceride accumulation in L. lipofer. (author)

UV-LEDs Efficiently Inactivate DNA and RNA Coliphages

Directory of Open Access Journals (Sweden)

Alyaa M. Zyara

2017-01-01

Full Text Available UV-LEDs are a new method of disinfecting drinking water. Some viruses are very resistant to UV and the efficiency of UV-LEDs to disinfect them needs to be studied. Drinking water was disinfected with UV-LEDs after spiking the water with MS2 and four UV- and/or Cl-resistant coliphages belonging to RNA or DNA coliphages isolated from municipal wastewater. UV-LEDs operating at a wavelength of 270 nm for 2 min with 120 mW of irradiation caused 0.93–2.73 Log10-reductions of coliphages tested in a reactor of a 5.2 L volume. Irradiation time of 10 min in the same system increased the Log10-reductions to 4.30–5.16. Traditional mercury UV (Hg-UV lamp at a 254 nm wavelength caused 0.67–4.08 Log10-reductions in 2 min and 4.56–7.21 Log10-reductions in 10 min in 10 mL of water. All coliphages tested except MS2 achieved 4 Log10-reductions with UV-LEDs at a dose that corresponded to 70 mWs/cm2 using Hg-UV. Thus, UV-LEDs are a promising method of disinfecting UV- and/or Cl-resistant viruses.

RNA synthesis during germination of UV-irradiated Dictyostelium discoideum spores

International Nuclear Information System (INIS)

Okaichi, Kumio

1987-01-01

UV irradiation to the spores of Dictyostelium discoideum NC4 resulted in a more prolonged delay of amoeba-emergence from swollen spores with increasing UV fluence. During the germination, an inhibition of total RNA synthesis and a shift of stage of maximum RNA synthesis to the later period were observed. The maximum poly(A) + RNA synthetic activity was found on an early stage of amoeba-emergence prior about 1 h to the beginning of rRNA synthesis in unirradiated spore germination; but, in UV-irradiated spore germination, the stage of maximum poly(A) + RNA synthesis shifted to the later stage of germination with increasing UV fluence. A decreased synthesis of poly(A) + RNA and a severe inhibition of rRNA synthesis were observed on UV-irradiated and germinated spores, but no significant inhibition of 4 - 5 S RNA synthesis was detected. Actinomycin D suppressed almost completely the rRNA synthesis of emerged amoebae but the drug apparently did not affect the emergence of amoebae at any stage of germination. It was postulated that the delay of amoeba-emergence in UV-irradiated spore must be mainly due to the shift of the stage of maximum synthesis of poly(A) + RNA to the later stage of germination. (author)

Effect of UV irradiation on the early development of silkworm embryos, (2). Development of irradiated eggs

Energy Technology Data Exchange (ETDEWEB)

Kobayashi, Y. (Hokkaido Univ., Sapporo (Japan). Faculty of Agriculture)

1981-02-01

The development of silkworm eggs irradiated with UV was compared with that of normal eggs. When the eggs were irradiated with UV from the lateral side immediately after oviposition, development was decelerated, but the germ band was produced. The side of the germ band that was irradiated with UV was abnormal with holes, but the opposite side was hole-free and normal. The normal half of the germ band splits longitudinally, but developed along with the abnormal half to form various malformations. When the eggs were irradiated from the ventral side, the ventral part of the germ band was abnormal at the early stage, the germ band did not concentrate to one place, and produced the half-embryos longitudinally divided by the median line. The UV irradiation at the beginning of the blastoderm stage produced similar results. In the areas irradiated by UV, cleavage nuclei invaded into the surrounding protoplasm, and mitotic figures were observed, but the cell number did not increase even with the advance of development unlike normal cells, whereas the sizes of the cells, their nuclei and nucleoli were enlarged, and intercellular space widened so that the cells were no longer in close contact. The germ band cells produced in the non-irradiated area were normal. The above results suggest that when either the protoplasm or the nucleus of a silkworm egg is damaged by UV, the effect first appears as the inhibition of cell division in the germ band, and as the enlargement of the cell, nucleus and nucleoli. It is presumed that this induces the subsequent inhibition of cell differentiation or abnormalities.

Review of short wavelength lasers

International Nuclear Information System (INIS)

Hagelstein, P.L.

1985-01-01

There has recently been a substantial amount of research devoted to the development of short wavelength amplifiers and lasers. A number of experimental results have been published wherein the observation of significant gain has been claimed on transitions in the EUV and soft x-ray regimes. The present review is intended to discuss the main approaches to the creation of population inversions and laser media in the short wavelength regime, and hopefully aid workers in the field by helping to provide access to a growing literature. The approaches to pumping EUV and soft x-ray lasers are discussed according to inversion mechanism. The approaches may be divided into roughly seven categories, including collisional excitation pumping, recombination pumping, direct photoionization and photoexcitation pumping, metastable state storage plus optical pumping, charge exchange pumping, and finally, the extension of free electron laser techniques into the EUV and soft x-ray regimes. 250 references

Review of short wavelength lasers

Energy Technology Data Exchange (ETDEWEB)

Hagelstein, P.L.

1985-03-18

There has recently been a substantial amount of research devoted to the development of short wavelength amplifiers and lasers. A number of experimental results have been published wherein the observation of significant gain has been claimed on transitions in the EUV and soft x-ray regimes. The present review is intended to discuss the main approaches to the creation of population inversions and laser media in the short wavelength regime, and hopefully aid workers in the field by helping to provide access to a growing literature. The approaches to pumping EUV and soft x-ray lasers are discussed according to inversion mechanism. The approaches may be divided into roughly seven categories, including collisional excitation pumping, recombination pumping, direct photoionization and photoexcitation pumping, metastable state storage plus optical pumping, charge exchange pumping, and finally, the extension of free electron laser techniques into the EUV and soft x-ray regimes. 250 references.

Effects of caffeine on DNA repair of UV-irradiated Dictyostelium discoideum

International Nuclear Information System (INIS)

Ohnishi, T.; Okaichi, K.; Ohashi, Y.; Nozu, K.

1981-01-01

Caffeine enhances the UV-killing of amoeboid cells of NC-4, but UV-irradiated γs-13 is insensitive to caffeine. UV-irradiated NC-4 becomes insensitive to the effect of caffeine during a postirradiation incubation in buffer for about 90 min, but γs-13 remains unchanged in the sensitivity to caffeine throughout the incubation for 180 min. Amoeboid cells of γs-13 can remove pyrimidine dimers as well as NC-4 even in the presence of caffeine. Caffeine inhibits rejoining of strand-breaks of DNA in UV-irradiated NC-4, but the rejoining in γs-13 is insensitive to caffeine. (author)

Comparison of UV action spectra for lethality and mutation in Salmonella typhimurium using a broad band source and monochromatic radiations

International Nuclear Information System (INIS)

Calkins, John; Selby, Christopher; Enoch, H.G.

1987-01-01

The UV-B region (280-320 nm) is thought to be primarily responsible for the mutagenic, lethal, and carcinogenic effects of solar radiation. We have conducted UV-B action spectroscopy for mutagenesis and survival of Ames' Salmonella typhimurium strain TA98 (uvrB, pKM101) using both monochromatic radiation from a dye laser and broader bandwidth radiation emitted from FS-20 sunlamps. A series of optical filters having different transmission cut-offs together with the sunlamp source provided bandwidths having successively less short wavelength components from which a ''broad band'' action spectrum was deduced. The two sets of action spectra differed both qualitatively and quantitatively: in comparison to the monochromatic action spectra, the ''broad band'' spectra showed up to a 200-fold reduced efficiency for both mutation induction and lethality by UV-B wavelengths. These results suggest a large protective effect of the background UV-A and/or visible radiations which were present during the broad spectrum irradiations and which are also present in solar radiation. Additional experiments show that to the extent tested this protective effect is not due to photo-reactivation or irradiance (dose rate) effects. (author)

Inactivation of Aspergillus flavus in drinking water after treatment with UV irradiation followed by chlorination

International Nuclear Information System (INIS)

Al-Gabr, Hamid Mohammad; Zheng, Tianling; Yu, Xin

2013-01-01

The disinfection process for inactivating microorganisms at drinking water treatment plants is aimed for safety of drinking water for humans from a microorganism, such as bacteria, viruses, algae, fungi by using chlorination, ozonation, UV irradiation, etc. In the present study, a combination of two disinfectants, UV irradiation followed by chlorination, was evaluated for inactivating Aspergillus flavus under low contact time and low dosage of UV irradiation. The results indicated an inverse correlation between the inactivation of A. flavus by using UV irradiation only or chlorination alone. By using UV radiation, the 2 log 10 control of A. flavus was achieved after 30 s of irradiation, while chlorination was observed to be more effective than UV, where the 2 log was achieved at chlorine concentration of 0.5, 1, 2 and 3 mg/l, in contact time of 60, 5, 1 and 1 min, respectively. However, combined use (UV irradiation followed by chlorination) was more effective than using either UV or chlorination alone; 5 s UV irradiation followed by chlorination produced 4 log 10 reduction of A. flavus at chlorine concentrations of 2 and 3 mg/l under a contact time of 15 min. The results indicated that efficiency of UV irradiation improves when followed by chlorination at low concentrations. - Highlights: • As a disinfectant, chlorine is more effective than UV in inactivating Aspergillus flavus. • As a combined method, UV irradiation followed by chlorination shows high efficiency. • UV irradiation can improve effectiveness of chlorination in reducing Aspergillus flavus

Influence of UV-irradiation on the nauplius larvae of the barnacle Chthamalus sp

International Nuclear Information System (INIS)

Hori, Masayuki; Nagayama, Shougo; Kawabe, Atsushi; Yamashita, Keiji.

1990-01-01

The purpose of this study is to investigate the influence of UV-irradiation on the nauplius larvae of the barnacle and to use this as the basis for researching the possibility of UV-irradiation as a new method for anti-macrofouling control. The nauplius larvae in the petri dishes were exposed to UV-irradiation (λ max = 253.7 nm), then the larval states and behaviour were observed. UV-intensisties were 3.0 mW·cm -2 -7.0 mW·cm -2 and the exposure time was 15 sec -10 min. The water in the petri dishes was changed intermittently but the larvae were not fed. The results were as follows: 1) UV-irradiation may have a delayed lethal effect and metamorphosis-inhibitory effect on the nauplius larvae. 2) The lethal effect of the sum of the dosages of UV on the larvae may nearly equate each other despite differences in each UV-intensity. 3) Within ca. 72 hr, 100 % of UV-irradiated larvae were dead with the dosage of at least 672 mW·sec·cm -2 and were incapable of swimming with the dosage of at least 168 mW·sec·cm -2 . 4) UV-irradiated larvae could not exuviate with the dosage of at least 246 mW·sec·cm -2 and could only exuviate with the dosage of 45 mW·sec·cm -2 . 5) After UV-irradiation even the 'actively swimming' larvae may have suffered some sort of physiological damage. (author)

Antigen-antibody reactions of UV-irradiated phage DNA

International Nuclear Information System (INIS)

Fink, A.

1976-01-01

The observation of others could be confirmed that UV-irradiated DNA is a better immunogen than unirradiated DNA. The author's immune sera contained a high amount of antibodies with a specific action against photoproducts in the DNA. The thymine dimer was identified as relevant photoproduct and thus as antigenic determinant. In comparison, the amount of unspecific antibodies reacting with denaturated DNA was low and varied between sera. Thymin-dimer antibodies showed a high specificity without cross-reaction with other pyrimidine dimers such as anti CC and anti CT; they belong to the class of IgG molecules. UV-irradiated dinucleotide dTpT is sufficient to induce the formation of antibodies reacting with the cis-syn thymine dimers in UV-irradiated DNA. Antibody binding is proportional to the UV doses applied to the DNA. When using completely denaturated DNA, there is a linear increase changing into a plateau at higher doses. The extent of antigen-antibody binding is strongly dependent on the degree of denaturation of the DNA. With increasing denaturation, the antibody binding of the DNA increases. The antigen-antibody reaction can thus be used to estimate the degree of denaturation of the DNA. There were no signs of an influence of the degree of denaturation of the DNA on the quantum yield of thymine dimers. The different amounts of antibodies is therefore due to the masking of thymine dimers in native DNA. When irradiating intact phage particles, there was no sign of an influence of the phages' protein covers on the antibody binding capacity of DNA compared with DNA irradiated in vitro. (orig.) [de

Spectral dependence of some UV-B and UV-C responses of Tetrahymena pyriformis irradiated with dye laser generated UV

International Nuclear Information System (INIS)

Calkins, John; Colley, Ed; Wheeler, John; Kentucky Univ., Lexington

1987-01-01

We have generated UV-B and UV-C radiations using a flashlamp driven tunable dye laser combined with frequency doubling crystals. Using this novel UV source, we have investigated lethality and its modification by growth phase, photoreactivation and caffeine in Tetrahymena pyriformis at 254 nm and from 260-315 nm in 5 nm steps. From the observed responses we have constructed action spectra for lethality, with or without caffeine (a repair inhibitor) and under conditions of photoreactivation. We have also estimated quantum efficiencies for these responses. Our observations suggest that complex changes in response occur at several wavelengths over the UV-C and UV-B regions. (author)

[Efficiency of photodecomposition of trace NDMA in water by UV irradiation].

Science.gov (United States)

Xu, Bing-Bing; Chen, Zhong-Lin; Qi, Fei; Ma, Jun

2008-07-01

Efficiency of photodecomposition of trace NDMA by UV irradiation was investigated with analyzing the initial concentration of NDMA, solution pH, irradiation area, irradiation intensity and water quality effect on NDMA photolysis. NDMA could be effectively photodegraded by UV irradiation. The removal efficiency of NDMA was 97.5% after 5 min of UV irradiation. Effect of initial NDMA concentration on photodecomposition of NDMA was not remarkable. With pH value ascending, the removal rate of NDMA photodecomposition decreased. The yields of photoquantum were more under lower solution pH than that under higher pH. NDMA had fastest reaction rate at solution pH = 2.2. Removal efficiency of NDMA increased with the available irradiation area ascending. Increscent ultraviolet irradiation intensity was good for NDMA degradation. Water quality affected the removal of NDMA slightly. The removal efficiency of NDMA in tap water and Songhua River raw water were 96.7% and 94.8%, respectively.

Effect of UV-irradiation on sol-gel optical films

International Nuclear Information System (INIS)

Yang Fan; Shen Jun; Zhou Bin; Wu Guangming; Luo Aiyun; Sun Qi

2005-01-01

Sol-gel optical films were deposited on K9 glass and silicon wafer substrates by spin-coating method and a high-pressure mercury lamp was used to perform ultraviolet treating to solidify these films and improve their performance. SEM, AFM, IR and ellipsometer were used to characterize the structure and optical properties of the films. Mechanical property of films was measured by pencil hardness-testing device. Laser damage threshold of films was measured by a Q-switched Nd:YAG high power laser with the wave length of 1064 nm and the pulse width of 15 ns. The results show that UV-irradiation can improve the mechanical property and increase the refractive index of the films. Besides, the nodules on the surface of the films can be changed into pits by UV-irradiation process, so the laser damage threshold of sol-gel thin films will be increased. After UV-irradiation the laser damage threshold of single-layer ZrO 2 film reached 50.6 J/cm 2 (1064 nm, 1 ns). It is found that UV-irradiation is an effective method to avoid the infiltrating between the layers, and the degree of homogeneity of the multilayer films can be improved by this way. (authors)

Immunological aspects of the investigation in the effect of external UV-irradiation and UV-irradiated bioliquids of the Langerhans cell

International Nuclear Information System (INIS)

Volyanskij, Yu.L.; Marchuk, L.M.; Telepneva, L.G.

1989-01-01

The origin and role of the Langerhans cell are considered in the immune response of the organism, as well as in a number of human diseases. It is noted that the antigen-presenting function of this macrophage suffers when taking glucocorticosteroid preparations, at AIDS and large doses of ultraviolet radiation. Therefore, the investigation of the effect of UV-irradiated blood reinfusion on the Langerhans cell will help to determine the possibilities of UV-irradiated blood therapy in treating a wide range of diseases, including AIDS, in the transplantation of organs and tissues. 163 refs.; 2 figs

Quercetin oxidation by horseradish peroxidase: The effect of UV-B irradiation

Directory of Open Access Journals (Sweden)

Savić Saša R.

2013-01-01

Full Text Available Horseradish peroxidase (HRP, a highly-investigated member of the peroxidase family has been known, among many other biological activities, to catalyze the oxidation of flavonoids and phenolic substrates overall, including quercetin. On the other hand, quercetin is very well known for its antioxidant activities, which in the case of UV external radiation is exibited partly in a preventive manner since it is an excellent UV-absorber. Therefore the aim of this investigation is to study quercetin oxidation by HRP in phosphate buffer under the conditions of UV-stress, i.e. continuous, prolonged UV-B irradiation. The results show that while UV-B irradiation affects the activity of HRP, and the overal rate of quercetin oxidation by HRP, it probably has very little effect on it for longer UV-B-irradiation periods (>30 min. [Acknowledgements. This work was supported by the Ministry of Education and Science of the Republic of Serbia under Project No.TR-34012 and OI-172044

In vivo activation of human immunodeficiency virus type 1 long terminal repeat by UV type A (UV-A) light plus psoralen and UV-B light in the skin of transgenic mice

OpenAIRE

Morrey, John D; Bourn, S M; Bunch, T D; Jackson, M K; Sidwell, R W; Barrows, L R; Daynes, R A; Rosen, C A

1991-01-01

UV irradiation has been shown to activate the human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR) in cell culture; however, only limited studies have been described in vivo. UV light has been categorized as UV-A (400 to 315 nm), -B (315 to 280 nm), or -C (less than 280 nm); the longer wavelengths are less harmful but more penetrative. Highly penetrative UV-A radiation constitutes the vast majority of UV sunlight reaching the earth's surface but is normally harmless. UV-B ir...

Coupling UV irradiation and electrocoagulation for reclamation of urban wastewater

International Nuclear Information System (INIS)

Cotillas, Salvador; Llanos, Javier; Miranda, Oscar G.; Díaz-Trujillo, Gerardo C.; Cañizares, Pablo; Rodrigo, Manuel A.

2014-01-01

Graphical abstract: - Highlights: • Iron electrodes allow removing turbidity and E. coli in urban wastewaters. • Enmeshment into growing flocs and oxidation are the key disinfection processes. • A synergistic effect of coupling UV and EC is found at low current densities. • Efficiency of UV irradiation is lowered at high current density. - Abstract: This work focuses on coupling electrocoagulation, with iron electrodes, and UV irradiation (photo-electrocoagulation) for the simultaneous removal of turbidity and E. coli from actual treated municipal wastewaters. Results show that single electrocoagulation behaves as a very efficient technology even using low current densities. E. coli is removed not only by the enmeshment of microorganisms into growing flocs, but also by the attack of electrochemically produced chlorine disinfectant species. Coupling UV irradiation to electrocoagulation with iron electrodes improves the process performance in terms of E. coli and turbidity removal. The effect of current density on process performance was evaluated, finding a synergistic interaction of both techniques at low current density (1.44 A m −2 ) but an antagonistic effect at higher values of current density (7.20 A m −2 ). This antagonistic effect is caused by the less efficient transmission of UV irradiation to the bulk solution due to the increase in the concentration of solids

Assessment of interplay between UV wavelengths, material surfaces and food residues in open surface hygiene validation

DEFF Research Database (Denmark)

Abban, Stephen; Jakobsen, Mogens; Jespersen, Lene

2014-01-01

The use of UV-visible radiation for detecting invisible residue on different surfaces as a means of validating cleanliness was investigated. Wavelengths at 365, 395, 435, 445, 470 and 490 nm from a monochromator were used to detect residues of beef, chicken, apple, mango and skim milk. These were....... It is important when UV-systems are used as real-time tools for assessing cleanliness of surfaces that the surface materials being illuminated are taken into account in the choice of lamp wavelength, in addition to expected residue. This will ensure higher confidence in results during the use of UV-light for real...

Bromate Formation Characteristics of UV Irradiation, Hydrogen Peroxide Addition, Ozonation, and Their Combination Processes

Directory of Open Access Journals (Sweden)

Naoyuki Kishimoto

2012-01-01

Full Text Available Bromate formation characteristics of six-physicochemical oxidation processes, UV irradiation, single addition of hydrogen peroxide, ozonation, UV irradiation with hydrogen peroxide addition (UV/H2O2, ozonation with hydrogen peroxide addition (O3/H2O2, and ozonation with UV irradiation (O3/UV were investigated using 1.88 μM of potassium bromide solution with or without 6.4 μM of 4-chlorobenzoic acid. Bromate was not detected during UV irradiation, single addition of H2O2, and UV/H2O2, whereas ozone-based treatments produced . Hydroxyl radicals played more important role in bromate formation than molecular ozone. Acidification and addition of radical scavengers such as 4-chlorobenzoic acid were effective in inhibiting bromate formation during the ozone-based treatments because of inhibition of hydroxyl radical generation and consumption of hydroxyl radicals, respectively. The H2O2 addition was unable to decompose 4-chlorobenzoic acid, though O3/UV and O3/H2O2 showed the rapid degradation, and UV irradiation and UV/H2O2 showed the slow degradation. Consequently, if the concentration of organic contaminants is low, the UV irradiation and/or UV/H2O2 are applicable to organic contaminants removal without bromate formation. However, if the concentration of organic contaminants is high, O3/H2O2 and O3/UV should be discussed as advanced oxidation processes because of their high organic removal efficiency and low bromate formation potential at the optimum condition.

Calibration of UV instruments and limitations on accuracy

International Nuclear Information System (INIS)

Clare, J.F.; Hamlin, J.D.

1993-01-01

Instruments measuring UV radiation may be classified as either spectrometers or broadband monitors; whilst the former determine irradiance as a function of wavelength the latter measure a summation of spectral irradiance weighted by some instrument response function which may be designed to approximate a desired action spectrum. For both classes a proper calibration requires the determination of the instrument's absolute spectral responsivity across the relevant wave-band together with an adequate determination of the wavelengths involved. (author). 7 refs

Overproduction of single-stranded-DNA-binding protein specifically inhibits recombination of UV-irradiated bacteriophage DNA in Escherichia coli

International Nuclear Information System (INIS)

Moreau, P.L.

1988-01-01

Overproduction of single-stranded DNA (ssDNA)-binding protein (SSB) in uvr Escherichia coli mutants results in a wide range of altered phenotypes. (i) Cell survival after UV irradiation is decreased; (ii) expression of the recA-lexA regulon is slightly reduced after UV irradiation, whereas it is increased without irradiation; and (iii) recombination of UV-damaged lambda DNA is inhibited, whereas recombination of nonirradiated DNA is unaffected. These results are consistent with the idea that in UV-damaged bacteria, SSB is first required to allow the formation of short complexes of RecA protein and ssDNA that mediate cleavage of the LexA protein. However, in a second stage, SSB should be displaced from ssDNA to permit the production of longer RecA-ssDNA nucleoprotein filaments that are required for strand pairing and, hence, recombinational repair. Since bacteria overproducing SSB appear identical in physiological respects to recF mutant bacteria, it is suggested that the RecF protein (alone or with other proteins of the RecF pathway) may help RecA protein to release SSB from ssDNA

Short wavelength sources and atoms and ions

International Nuclear Information System (INIS)

Kennedy, E.T.

2008-01-01

The interaction of ionizing radiation with atoms and ions is a key fundamental process. Experimental progress has depended in particular on the development of short wavelength light sources. Laser-plasma and synchrotron sources have been exploited for several decades and most recently the development of short wavelength Free Electron Laser (FEL) sources is revolutionizing the field. This paper introduces laser plasma and synchrotron sources through examples of their use in studies of the interaction of ionizing radiation with atoms and ions, ranging from few-electron atomic and ionic systems to the many-electron high atomic number actinides. The new FEL source (FLASH) at DESY is introduced. (author)

A new diagnostic for the tritium phase of JET covering the visible and UV wavelength range

International Nuclear Information System (INIS)

Morsi, H.W.; Hatzky, R.; Hellermann, M. von

1991-01-01

The objectives of an active-phase direct optical link between the JET tokamak and spectral instruments beyond the biological shield are manifold. The present optical fibre links, which are used as a standard at JET, may be subjected to much enhanced radiation levels in future operations with D-T plasmas, and a direct optical link, based on a system of remotely controllable relay mirrors, will be a vital test for future activated fusion devices. A further aim is to extend the spectral range of exploitable charge exchange (CX) lines to shorter wavelengths, which is presently limited by the transmission of quartz fibres to CX lines above 4000 A. The latter aspect is particularly relevant in the case of HeII where the sole CX line of HeII (n = 4 to 3) in the visible, is superimposed by a BeIV CX line (n = 8 to 6) at the same wavelength (4685 A). This fact constraints the present helium analysis to plasma conditions with n(Be)<0.3·n(He). For future alpha particle studies, especially at low alpha particle densities, this constraint may require either sophisticated analysis procedures or alternatively the use of other less ''disturbed'' lines, possibly in the UV wavelength range. Finally the UV link is intended to provide an optical transfer channel for short optical jumpers to other JET observation ports - for example coherent fibre bundles imaging the X-point strike zone - to the diagnostic instruments in the roof laboratory of JET. (author) 1 ref., 6 figs

UV exposure in cars.

Science.gov (United States)

Moehrle, Matthias; Soballa, Martin; Korn, Manfred

2003-08-01

There is increasing knowledge about the hazards of solar and ultraviolet (UV) radiation to humans. Although people spend a significant time in cars, data on UV exposure during traveling are lacking. The aim of this study was to obtain basic information on personal UV exposure in cars. UV transmission of car glass samples, windscreen, side and back windows and sunroof, was determined. UV exposure of passengers was evaluated in seven German middle-class cars, fitted with three different types of car windows. UV doses were measured with open or closed windows/sunroof of Mercedes-Benz E 220 T, E 320, and S 500, and in an open convertible car (Mercedes-Benz CLK). Bacillus subtilis spore film dosimeters (Viospor) were attached to the front, vertex, cheeks, upper arms, forearms and thighs of 'adult' and 'child' dummies. UV wavelengths longer than >335 nm were transmitted through car windows, and UV irradiation >380 nm was transmitted through compound glass windscreens. There was some variation in the spectral transmission of side windows according to the type of glass. On the arms, UV exposure was 3-4% of ambient radiation when the car windows were shut, and 25-31% of ambient radiation when the windows were open. In the open convertible car, the relative personal doses reached 62% of ambient radiation. The car glass types examined offer substantial protection against short-wave UV radiation. Professional drivers should keep car windows closed on sunny days to reduce occupational UV exposure. In individuals with polymorphic light eruption, produced by long-wave UVA, additional protection by plastic films, clothes or sunscreens appears necessary.

Conformational Effects of UV Light on DNA Origami.

Science.gov (United States)

Chen, Haorong; Li, Ruixin; Li, Shiming; Andréasson, Joakim; Choi, Jong Hyun

2017-02-01

The responses of DNA origami conformation to UV radiation of different wavelengths and doses are investigated. Short- and medium-wavelength UV light can cause photo-lesions in DNA origami. At moderate doses, the lesions do not cause any visible defects in the origami, nor do they significantly affect the hybridization capability. Instead, they help relieve the internal stress in the origami structure and restore it to the designed conformation. At high doses, staple dissociation increases which causes structural disintegration. Long-wavelength UV does not show any effect on origami conformation by itself. We show that this UV range can be used in conjunction with photoactive molecules for photo-reconfiguration, while avoiding any damage to the DNA structures.

Replicative intermediates in UV-irradiated Simian virus 40

International Nuclear Information System (INIS)

Clark, J.M.; Hanawalt, P.C.

1984-01-01

The authors have used Simian virus 40 (SV40) as a probe to study the replication of UV-damaged DNA in mammalian cells. Viral DNA replication in infected monkey kidney cells was synchronized by incubating a mutant of SV40 (tsA58) temperature-sensitive for the initiation of DNA synthesis at the restrictive temperature and then adding aphidicolin to temporarily inhibit DNA synthesis at the permissive temperature while permitting pre-replicative events to occur. After removal of the drug, the infected cells were irradiated at 100 J/m 2 (254 nm) to produce 6-7 pyrimidine dimers per SV40 genome, and returned to the restrictive temperature to prevent reinitiation of replication from the SV40 origin. Replicative intermediates (RI) were labeled with [ 3 H]thymidine. The size distribution of daughter DNA strands in RI isolated shortly after irradiation was skewed towards lengths less than the interdimer spacing in parental DNA; this bias persisted for at least 1 h after irradiation, but disappeared within 3 h by which time the size of the newly-synthesized DNA exceeded the interdimer distance. Evidence was obtained for the generation at late times after irradiation, of Form I molecules in which the daughter DNA strand contain dimers. Thus DNA strand exchange as well as trans-dimer synthesis may be involved in the generation of supercoiled Form I DNA from 0V-damaged SV40 replicative intermediates. (Auth.)

Effect of reactive monomer on PS-b-P2VP film with UV irradiation

Science.gov (United States)

Kim, H. J.; Shin, D. M.

2012-03-01

Poly(styrene-b-2-vinyl pyridine) (PS-b-P2VP) lamellar film which is hydrophobic block hydrophilic polyelectrolyte block polymer of 52 kg/mol -b- 57 kg/mol and PS-b-P2VP film with reactive monomer (RM257) were prepared for photonic gel films. The lamellar stacks, which is alternating layer of hydrophilic and hydrophobic part of PS-b-P2VP. We reported about the influence of reactive monomer on those photonic gel films. Added reactive monomer photonic gel film had higher absorbance than pure photonic gel films. And band gaps of the lamellar films shifted by the time of UV light irradiation. That Photonic gel films were measured with the UV spectrophotometer. As a result the photonic gel film with reactive monomer had more clear color. The lamellar films were swollen by DI water, Ethyl alcohol (aq) and calcium carbonate solution. Since the domain spacing of dried photonic gel films were not showing any color in visible wavelength. The band gap of the lamellar films were drastically shifted to longer wavelength swollen by calcium carbonate solution (absorbance peak 565nm-->617nm). And the lamellar films were shifted to shorter wave length swollen by ethanol (absorbance peak 565nm-->497nm). So each Photonic gel film showed different color.

Effect of UV-A and UV-B irradiation on the metabolic profile of aqueous humor in rabbits analyzed by 1H NMR spectroscopy.

Science.gov (United States)

Tessem, May-Britt; Bathen, Tone F; Cejková, Jitka; Midelfart, Anna

2005-03-01

This study was conducted to investigate metabolic changes in aqueous humor from rabbit eyes exposed to either UV-A or -B radiation, by using (1)H nuclear magnetic resonance (NMR) spectroscopy and unsupervised pattern recognition methods. Both eyes of adult albino rabbits were irradiated with UV-A (366 nm, 0.589 J/cm(2)) or UV-B (312 nm, 1.667 J/cm(2)) radiation for 8 minutes, once a day for 5 days. Three days after the last irradiation, samples of aqueous humor were aspirated, and the metabolic profiles analyzed with (1)H NMR spectroscopy. The metabolic concentrations in the exposed and control materials were statistically analyzed and compared, with multivariate methods and one-way ANOVA. UV-B radiation caused statistically significant alterations of betaine, glucose, ascorbate, valine, isoleucine, and formate in the rabbit aqueous humor. By using principal component analysis, the UV-B-irradiated samples were clearly separated from the UV-A-irradiated samples and the control group. No significant metabolic changes were detected in UV-A-irradiated samples. This study demonstrates the potential of using unsupervised pattern recognition methods to extract valuable metabolic information from complex (1)H NMR spectra. UV-B irradiation of rabbit eyes led to significant metabolic changes in the aqueous humor detected 3 days after the last exposure.

Evaluation of the desert dust effects on global, direct and diffuse spectral ultraviolet irradiance

Directory of Open Access Journals (Sweden)

R. Román

2013-01-01

Full Text Available This paper presents a study of a strong desert dust episode over the Iberian Peninsula, and its effect on the spectral ultraviolet (UV irradiance in Granada, Spain. Remote sensing measurements, forecast models, and synoptic analysis are used to identify a Saharan desert dust outbreak that affected the Iberian Peninsula starting 20 July 2009. Additionally, a Bentham DMc150 spectroradiometer is employed to obtain global, direct and diffuse spectral UV irradiances every 15 minutes in Granada. The desert dust caused a large attenuation of the direct UV irradiance (up to 55%, while the diffuse UV irradiance increased up to 40% at 400 nm. The UVSPEC/LibRadtran radiative transfer model is used to study the spectral dependence of the experimental UV irradiance ratios (ratios of spectral irradiance for the day with the highest aerosol load to that measured in days with low–moderate load. The spectral increase or decrease of the UV direct irradiance ratios depends on a new parameter: a threshold wavelength. The spectral dependence of the UV diffuse irradiance ratio can be explained because under the influence of the intense dust outbreak, the Mie scattering by aerosols at shorter wavelengths is stronger than the Rayleigh scattering by gases. Finally, the sensitivity analysis of the aerosol absorption properties shows a substantial attenuation of UV spectral irradiance with a weak spectral dependence.

Determining optimum wavelength of ultraviolet rays to pre-exposure of non-uniformity error correction in Gafchromic EBT2 films

Science.gov (United States)

Katsuda, Toshizo; Gotanda, Rumi; Gotanda, Tatsuhiro; Akagawa, Takuya; Tanki, Nobuyoshi; Kuwano, Tadao; Noguchi, Atsushi; Yabunaka, Kouichi

2018-03-01

Gafchromic films have been used to measure X-ray doses in diagnostic radiology such as computed tomography. The double-exposure technique is used to correct non-uniformity error of Gafchromic EBT2 films. Because of the heel effect of diagnostic x-rays, ultraviolet A (UV-A) is intended to be used as a substitute for x-rays. When using a UV-A light-emitting diode (LED), it is necessary to determine the effective optimal UV wavelength for the active layer of Gafchromic EBT2 films. This study evaluated the relation between the increase in color density of Gafchromic EBT2 films and the UV wavelengths. First, to correct non-uniformity, a Gafchromic EBT2 film was pre-irradiated using uniform UV-A radiation for 60 min from a 72-cm distance. Second, the film was irradiated using a UV-LED with a wavelength of 353-410 nm for 60 min from a 5.3-cm distance. The maximum, minimum, and mean ± standard deviation (SD) of pixel values of the subtraction images were evaluated using 0.5 inches of a circular region of interest (ROI). The highest mean ± SD (8915.25 ± 608.86) of the pixel value was obtained at a wavelength of 375 nm. The results indicated that 375 nm is the most effective and sensitive wavelength of UV-A for Gafchromic EBT2 films and that UV-A can be used as a substitute for x-rays in the double-exposure technique.

Color change of tourmaline by heat treatment and electron beam irradiation: UV-Visible, EPR, and Mid-IR spectroscopic analyses

Science.gov (United States)

Maneewong, Apichate; Seong, Baek Seok; Shin, Eun Joo; Kim, Jeong Seog; Kajornrith, Varavuth

2016-01-01

The color of pink tourmaline gemstone changed to colorless when heating at temperature of 600 °C in air. This colorless tourmaline recovered its pink color when irradiated with an electron beam (e-beam) of 800 kGy. The origin of the color change was investigated in three types of tourmaline gemstones, two pink are from Afghanistan and one green are from Nigeria, by using Ultraviolet-visible spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FTIR), Electron paramagnetic resonance (EPR), and Energy Dispersive X-ray Fluorescence (EDXRF). The UV-Vis absorption spectrum of the pink tourmaline with higher Mn concentration (T2, 0.24 wt%) showed characteristic absorption peaks originating from the Mn3+ color center: two absorption bands centered at wavelength of 396 and 520 nm, respectively. Both absorption bands disappeared when heated in air at 600 °C and then reappeared when irradiated with an e-beam at 800 kGy. EPR T2 spectra showed that the color change was related to the valence change of Mn3+ to Mn2+ and vice versa. The pink tourmaline of lower MnO content (T1, 0.08 wt%) also became colorless when heated, but the color was not recovered when the gemstone underwent e-beam irradiation. Instead, a yellow color was obtained. UV-Vis and FTIR spectra indicated that this yellow color originated from a decomposition of the hydroxyl group (-OH) into O- and Ho by the e-beam irradiation. Green tourmaline did not show any color change with either heat treatment or e-beam irradiation.

In Vitro Repair of UV-Irradiated Micrococcus luteus Bacteriophage N1 Transfecting DNA 1

Science.gov (United States)

Mahler, Inga; George, Jeanne; Grossman, Lawrence

1974-01-01

Calcium-treated UV-sensitive, host cell reactivation− strains of Micrococcus luteus are infected with UV-irradiated N1 DNA. In strains lacking UV endonuclease, in vitro treatment of the irradiated DNA results in transfection enhancement. PMID:4823319

Monoclonal antibodies reactive with common tumor antigens on UV-induced tumors also react with hyperplastic UV-irradiated skin

International Nuclear Information System (INIS)

Spellman, C.W.; Beauchamp, D.A.

1986-01-01

Most murine skin tumors induced by ultraviolet light (UVB, 280-340 nm) can be successfully transplanted only into syngeneic hosts that have received subcarcinogenic doses of UVB. The tumor susceptible state is long-lived and mediated by T suppressor cells that control effector responses against common antigens on UV-induced tumors. Because antigen specific suppression arises prior to the appearance of a tumor, questions arise about the source of the original antigen. They have previously reported transplantation studies indicating that UV-irradiated skin is antigenically cross-reactive with UV-induced tumors. They now report on flow cytometry analyses showing that a series of MoAb reactive with common antigens expressed by UV-induced tumors are also reactive on cells from UV-irradiated skin. Various antigens appear at different times in the UV irradiation scheme, and some persist while others are transient. They speculate that the common antigens detected may be the ones to which functional suppression is directed. If true, these results suggest that successful tumors need not escape host defenses to emerge. Rather, tumors may arise and grow progressively if they express antigens that cross-react with specificities to which the host has previously mounted a suppressive response

Electron irradiation of near-UV GaN/InGaN light emitting diodes

Energy Technology Data Exchange (ETDEWEB)

Lee, In-Hwan; Cho, Han-Su [Department of Materials Science and Engineering, Korea University, Seoul (Korea, Republic of); Polyakov, Alexander Y.; Smirnov, N.B.; Shchemerov, I.V.; Zinovyev, R.A.; Didenko, S.I.; Lagov, P.B. [National University of Science and Technology MISiS, Moscow (Russian Federation); Shmidt, N.M.; Shabunina, E.I. [Ioffe Physico-Technical Institute, St. Petersburg (Russian Federation); Tal' nishnih, N.A. [Submicron Heterostructures for Microelectronics Research and Engineering Center, St. Petersburg (Russian Federation); Hwang, Sung-Min [Soft-Epi, Inc., Opo-ro 240, Gwangju-si, Gyeonggi-do (Korea, Republic of); Pearton, S.J. [Department of Materials Science and Engineering, University of Florida, Gainesville, FL (United States)

2017-10-15

Irradiation with 6 MeV electrons of near-UV (peak wavelength 385-390 nm) multi-quantum-well (MQW) GaN/InGaN light emitting diodes (LEDs) causes an increase in density of deep electron traps near E{sub c} -0.8 and E{sub c} -1 eV, and correlates to a 90% decrease of electroluminescence (EL) efficiency after a fluence of 1.1 x 10{sup 16} cm{sup -2}. The likely origin of the EL efficiency decrease is this increase in concentration of the E{sub c} -0.8 eV and E{sub c} -1 eV traps. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Results of preliminary experiments on tritium decontamination by UV irradiation

International Nuclear Information System (INIS)

Oya, Yasuhisa; Shu, Wataru; O'hira, Shigeru; Hayashi, Takumi; Nishi, Masataka

2000-03-01

In the point of view of protection of workers from the radiation exposure and the limitation of the contamination with radioactive materials, it is important to decontaminate mobile tritium from plasma facing components of a nuclear fusion reactor at the beginning of their maintenance work. It is considered that the heating is the most effective method for decontamination. However, it is important to develop new decontamination method of adsorbed hydro-carbon based substances from the materials that cannot be heated or the inner pipe of double pipes. This report presents results of preliminary experiments performed for the development of the effective tritium decontamination technique pursuing under US/Japan collaborative program on technology for fusion-fuel processing (Annex IV). In the experiments, the effects of Ultra Violet (UV) irradiation on tritium removal from some kinds of materials, such as poly vinyl chloride -(CH 2 CHCl) n - film, polyethylene film and graphite samples coated by C 2 H 2 plasma were examined. As the result of UV irradiation, it was confined that hydrogen and carbon based compounds could be released from the specimen during UV irradiation. It is concluded that UV irradiation is one of the hopeful candidates for effective tritium decontamination. (author)

Ultraviolet and short wavelength visible light exposure: why ultraviolet protection alone is not adequate.

Science.gov (United States)

Reichow, Alan W; Citek, Karl; Edlich, Richard F

2006-01-01

The danger of exposure to ultraviolet (UV) radiation in both the natural environment and artificial occupational settings has long been recognized by national and international standards committees and worker safety agencies. There is an increasing body of literature that suggests that protection from UV exposure is not enough. Unprotected exposure to the short wavelengths of the visible spectrum, termed the "blue light hazard", is gaining acceptance as a true risk to long-term visual health. Global standards and experts in the field are now warning that those individuals who spend considerable time outdoors should seek sun filter eyewear with high impact resistant lenses that provide 100% UV filtration, high levels of blue light filtration, and full visual field lens/frame coverage as provided by high wrap eyewear. The Skin Cancer Foundation has endorsed certain sunglasses as "product[s]...effective [as] UV filter[s] for the eyes and surrounding skin". However, such endorsement does not necessarily mean that the eyewear meets all the protective needs for outdoor use. There are several brands that offer products with such protective characteristics. Performance sun eyewear by Nike Vision, available in both corrective and plano (nonprescription) forms, is one such brand incorporating these protective features.

Inferring brown carbon content from UV aerosol absorption measurements during biomass burning season

Science.gov (United States)

Mok, J.; Krotkov, N. A.; Arola, A. T.; Torres, O.; Jethva, H. T.; Andrade, M.; Labow, G. J.; Eck, T. F.; Li, Z.; Dickerson, R. R.; Stenchikov, G. L.; Osipov, S.

2015-12-01

Measuring spectral dependence of light absorption by colored organic or "brown" carbon (BrC) is important, because of its effects on photolysis rates of ozone and surface ultraviolet (UV) radiation. Enhanced UV spectral absorption by BrC can in turn be exploited for simultaneous retrievals of BrC and black carbon (BC) column amounts in field campaigns. We present an innovative ground-based retrieval of BC and BrC volume fractions and their mass absorption efficiencies during the biomass burning season in Santa Cruz, Bolivia in September-October 2007. Our method combines retrieval of BC volume fraction using AERONET inversion in visible wavelengths with the inversion of total BC+BrC absorption (i.e., column effective imaginary refractive index, kmeas) using Diffuse/Direct irradiance measurements in UV wavelengths. First, we retrieve BrC volume fraction by fitting kmeas at 368nm using Maxwell-Garnett (MG) mixing rules assuming: (1) flat spectral dependence of kBC, (2) known value of kBrC at 368nm from laboratory absorption measurements or smoke chamber experiments, and (3) known BC volume fraction from AERONET inversion. Next, we derive kBrC in short UVB wavelengths by fitting kmeas at 305nm, 311nm, 317nm, 325nm, and 332nm using MG mixing rules and fixed volume fractions of BC and BrC. Our retrievals show larger than expected spectral dependence of kBrC in UVB wavelengths, implying reduced surface UVB irradiance and inhibited photolysis rates of surface ozone destruction. We use a one-dimensional chemical box model to show that the observed strong wavelength dependence of BrC absorption leads to inhibited photolysis of ozone to O(1D), a loss mechanism, while having little impact or even accelerating photolysis of NO2, an ozone production mechanism. Although BC only absorption in biomass burning aerosols is important for climate radiative forcing in the visible wavelengths, additional absorption by BrC is important because of its impact on surface UVB radiation

Heat-shock-induced enhanced reactivation of UV-irradiated Herpesvirus

Energy Technology Data Exchange (ETDEWEB)

Yager, J.D.; Zurlo, J.; Penn, A.L.

1985-09-01

The objective of this study was to compare the ability of heat shock (HS) with that of another type of cellular stress, UV irradiation, to cause the induction of enhanced viral reactivation, a process that may represent an SOS-type repair process in mammalian cells. These results indicate that, like UV irradiation, HS at levels inhibitory to cell growth induced enhanced viral reactivation in Vero cells. The results also suggest that at least two proteins in the HS protein family are not necessary for this response to occur. (Auth.). 27 refs.; 5 figs.

Self-amplified spontaneous emission for short wavelength coherent radiation

International Nuclear Information System (INIS)

Kim, K.J.; Xie, M.

1992-09-01

We review the recent progress in our understanding of the self-amplified spontaneous emission (SASE), emphasizing the application to short wavelength generation. Simple formulae are given for the start-up, exponential gain and the saturation of SASE. Accelerator technologies producing high brightness electron beams required for short wavelength SASE are discussed. An example utilizing electron beams from a photocathode-linac system to produce 4nm SASE in the multigigawatt range is presented

Changes in the DRIFT Spectra of Softwood Materials Irradiated by UV-laser as a Function of Energy

Directory of Open Access Journals (Sweden)

BARTA, Edit

2005-01-01

Full Text Available We investigated energy dependence of the effect of UV-laser irradiation on the DRIFT spectra of softwood samples. Changes in the spectra of softwoods have been studied with 248.5 nm wavelength of UV-laser radiation. To monitor the energy dependence, different number of laser impulses were directed towards the sample’s surface. The dependence on energy of different bands can be listed into four groups. Broad absorption bands, which belong to the same chemical groups located at various positions, do not show consistent changes due to the absorption of different energy dozes. The intensity of OH bands for the treated samples can be higher or lower depending on the amount of radiation energy. In the CHn and in the band of non-conjugated carbonyl groups only absorption increase can be observed. Bands resulting from only one chemical component, and containing no other absorption maxima around them, uniformly decreased. The regions where the band of a chemical component lies next to another one, showed no consistent changes during the irradiation. The initial decrease was followed by increase.

Functional characterization of spectral tuning mechanisms in the great bowerbird short-wavelength sensitive visual pigment (SWS1), and the origins of UV/violet vision in passerines and parrots.

Science.gov (United States)

van Hazel, Ilke; Sabouhanian, Amir; Day, Lainy; Endler, John A; Chang, Belinda S W

2013-11-13

One of the most striking features of avian vision is the variation in spectral sensitivity of the short wavelength sensitive (SWS1) opsins, which can be divided into two sub-types: violet- and UV- sensitive (VS & UVS). In birds, UVS has been found in both passerines and parrots, groups that were recently shown to be sister orders. While all parrots are thought to be UVS, recent evidence suggests some passerine lineages may also be VS. The great bowerbird (Chlamydera nuchalis) is a passerine notable for its courtship behaviours in which males build and decorate elaborate bower structures. The great bowerbird SWS1 sequence possesses an unusual residue combination at known spectral tuning sites that has not been previously investigated in mutagenesis experiments. In this study, the SWS1 opsin of C. nuchalis was expressed along with a series of spectral tuning mutants and ancestral passerine SWS1 pigments, allowing us to investigate spectral tuning mechanisms and explore the evolution of UV/violet sensitivity in early passerines and parrots. The expressed C. nuchalis SWS1 opsin was found to be a VS pigment, with a λmax of 403 nm. Bowerbird SWS1 mutants C86F, S90C, and C86S/S90C all shifted λmax into the UV, whereas C86S had no effect. Experimentally recreated ancestral passerine and parrot/passerine SWS1 pigments were both found to be VS, indicating that UV sensitivity evolved independently in passerines and parrots from a VS ancestor. Our mutagenesis studies indicate that spectral tuning in C. nuchalis is mediated by mechanisms similar to those of other birds. Interestingly, our ancestral sequence reconstructions of SWS1 in landbird evolution suggest multiple transitions from VS to UVS, but no instances of the reverse. Our results not only provide a more precise prediction of where these spectral sensitivity shifts occurred, but also confirm the hypothesis that birds are an unusual exception among vertebrates where some descendants re-evolved UVS from a violet type

Post-irradiation replication and repair in UV-irradiated cells of Proteus mirabilis depends on protein synthesis and a functioning rec+ gene

International Nuclear Information System (INIS)

Hofemeister, J.

1977-01-01

The amount of and the molecular weight of newly synthesized DNA (piDNA) as well as its repair after UV irradiation in excision-proficient strains of P.mirabilis and E.coli K12 have been compared. A fraction of post-replication repair (PRR) in P.mirabilis is found to be dependent on de novo protein synthesis after UV irradiation. Pre-irradiation by UV and pre-treatment with nalidixic acid increase the efficiency of post-irradiation replication and PRR even in the presence of chloramphenicol. An inducible repair function in P.mirabilis is supposed to stimulate post-irradiation replication and repair. (author)

Loss of photoreactivation in UV-irradiated cultured fish cells under different conditions

International Nuclear Information System (INIS)

Mano, Y.; Kator, K.; Egami, N.

1982-01-01

CAF-MM1 cells derived from a goldfish have photoreactivability for the damage induced by ultraviolet light. When UV-irradiated cells were incubated in the dark at 26 0 C, the longest interval in which photoreactivation (PR) was observed, measured by colony formation technique, was about 30h after the UV irradiation. However, if the cells were incubated at 20 0 C, the effective time was prolonged. Since each time appeared to correspond to the doubling time of the cells at each temperature, the loss of photoreactivability is suggested to be closely related to cell growth or progression of cell cycle. The loss of PR was not observed in the cells held in confluence up to 48h after UV irradiation. Photoreactivating enzyme in growing CAF-MM1 cells incubated in the dark for 24h after UV irradiation was shown to be active, so that it is not possible that the cause of the loss of PR is change in the activity of photoreactivating enzyme. (author)

Sensitivity of Vibrio cholerae cells to lethal and mutagenic effect of UV-irradiation mediated by plasmids

International Nuclear Information System (INIS)

Tiganova, I.G.; Evdokimova, N.M.; Aleshkin, G.I.

1988-01-01

The effect of UV-irradiation on Vibrio cholerae cells and its changes mediated by the plasmid R245 have been studied. Vibrio cholerae strains 569B and RV31 have been shown to be considerably more sensitive to lethal effect of UV-irradiation as compared with Escherichia coli and Salmonella typhimurium cells. Highly toxigenic strain 569B and practically atoxigenic strain RV31 have the same UV-sensitivity. Lethla effect of UV-irradiation on Vibrio cholerae cells is incresed when the irradiated cells are plated on enriched media. UV-induction of mutations was not registered in plasmidless strains of Vibrio cholerae. Plasmid R245 increase UV-resistance of vibrio cells and makes them UV-mutable

[UV-irradiation-induced skin cancer as a new occupational disease].

Science.gov (United States)

Diepgen, T L; Drexler, H; Elsner, P; Schmitt, J

2015-03-01

With the revision of the German Ordinance on Occupational Diseases, skin cancer due to UV irradiation was amended as a new occupational disease to the list of occupational diseases in Germany. The new occupational disease BK 5103 has the following wording: "Squamous cell carcinoma or multiple actinic keratosis of the skin caused by natural UV irradiation". Actinic keratoses are to be considered as multiple according to this new occupational diseases if they occur as single lesions of more than five annually, or are confluent in an area > 4 cm(2) (field cancerization). It is estimated that more than 2.5 million employees are exposed to natural UV irradiation due to their work (outdoor workers) in Germany and therefore have an increased risk of skin cancer. In this article the medical and technical prerequisites which have to be fulfilled for this new occupational disease in Germany are introduced.

DNA repair capacity and rate of excision repair in UV-irradiated mammalian cells

International Nuclear Information System (INIS)

Inoue, Masao; Takebe, Hiraku.

1978-01-01

Repair capacities of five mammalian cell strains were measured by colony-forming ability, HCR of UV-irradiated virus, UDS, pyrimidine dimer excision, and semi-conservative DNA replication. Colony-forming ability of UV-irradiated cells was high for human amnion FL cells and mouse L cells, slightly low for African green monkey CV-1 cells, and extremely low for xeroderma pigmentosum cells. HCR of UV-irradiated Herpes simplex virus was high in CV-1 cells, FL and normal human fibroblast cells, low in both XP and L cells. The amount of UDS was high in FL and normal human fibroblast cells, considerably low in CV-1 cells, and essentially no UDS was observed in XP cells. Rate of UDS after UV-irradiation was slower for CV-1 cells than FL and human fibroblast cells. Rate of the excision of thymine-containing dimers from the acid-insoluble fraction during post-irradiation incubation of the cells was rapid in FL and normal human cells and slow in CV-1 cells, and no excision took place in XP cells. Semi-conservative DNA synthesis was reduced after UV-irradiation in all cell lines, but subsequently recovered in FL, normal human and CV-1 cells. The onset of recovery was 4 h after UV-irradiation for FL and normal human cells, but about 6 h for CV-1 cells. The apparent intermediate repair of CV-1 cells except for HCR may be related to the slow rate of excision repair. ''Patch and cut'' model is more favorable than ''cut and patch'' model to elucidate these results. (auth.)

Fullerene-catalyzed reduction of azo derivatives in water under UV irradiation

KAUST Repository

Guo, Yong; Li, Wengang; Yan, Jingjing; Moosa, Basem; Amad, Maan H.; Werth, Charles; Khashab, Niveen M.

2012-01-01

Metal-free fullerene (C60) was found to be an effective catalyst for the reduction of azo groups in basic aqueous solution under UV irradiation in the presence of NaBH4. Use of NaBH4 by itself is not sufficient to reduce the azo dyes without the assistance of a metal catalyst such as Pd and Ag. Experimental and theoretical results suggest that C 60 catalyzes this reaction by using its vacant orbital to accept the electron in the bonding orbital of azo dyes, which leads to the activation of the N=N bond. UV irradiation increases the ability of C60 to interact with electron-donor moieties in azo dyes. Filling a vacancy: Experimental and theoretical methods have been combined to show that C60-catalyzed reductions of azo compounds form aromatic amines under UV irradiation (see scheme). The obtained results show that C60 acts as an electron acceptor to catalyze the reduction of azo compounds, and the role of UV irradiation is to increase the ability of C60 to interact with electron-donor moieties in azo compounds. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fullerene-catalyzed reduction of azo derivatives in water under UV irradiation

KAUST Repository

Guo, Yong

2012-09-27

Metal-free fullerene (C60) was found to be an effective catalyst for the reduction of azo groups in basic aqueous solution under UV irradiation in the presence of NaBH4. Use of NaBH4 by itself is not sufficient to reduce the azo dyes without the assistance of a metal catalyst such as Pd and Ag. Experimental and theoretical results suggest that C 60 catalyzes this reaction by using its vacant orbital to accept the electron in the bonding orbital of azo dyes, which leads to the activation of the N=N bond. UV irradiation increases the ability of C60 to interact with electron-donor moieties in azo dyes. Filling a vacancy: Experimental and theoretical methods have been combined to show that C60-catalyzed reductions of azo compounds form aromatic amines under UV irradiation (see scheme). The obtained results show that C60 acts as an electron acceptor to catalyze the reduction of azo compounds, and the role of UV irradiation is to increase the ability of C60 to interact with electron-donor moieties in azo compounds. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Temporal variation of optimal UV exposure time over Korea: risks and benefits of surface UV radiation

Science.gov (United States)

Lee, Y. G.; Koo, J. H.

2015-12-01

Solar UV radiation in a wavelength range between 280 to 400 nm has both positive and negative influences on human body. Surface UV radiation is the main natural source of vitamin D, providing the promotion of bone and musculoskeletal health and reducing the risk of a number of cancers and other medical conditions. However, overexposure to surface UV radiation is significantly related with the majority of skin cancer, in addition other negative health effects such as sunburn, skin aging, and some forms of eye cataracts. Therefore, it is important to estimate the optimal UV exposure time, representing a balance between reducing negative health effects and maximizing sufficient vitamin D production. Previous studies calculated erythemal UV and vitamin-D UV from the measured and modelled spectral irradiances, respectively, by weighting CIE Erythema and Vitamin D3 generation functions (Kazantzidis et al., 2009; Fioletov et al., 2010). In particular, McKenzie et al. (2009) suggested the algorithm to estimate vitamin-D production UV from erythemal UV (or UV index) and determined the optimum conditions of UV exposure based on skin type Ⅱ according to the Fitzpatrick (1988). Recently, there are various demands for risks and benefits of surface UV radiation on public health over Korea, thus it is necessary to estimate optimal UV exposure time suitable to skin type of East Asians. This study examined the relationship between erythemally weighted UV (UVEry) and vitamin D weighted UV (UVVitD) over Korea during 2004-2012. The temporal variations of the ratio (UVVitD/UVEry) were also analyzed and the ratio as a function of UV index was applied in estimating the optimal UV exposure time. In summer with high surface UV radiation, short exposure time leaded to sufficient vitamin D and erythema and vice versa in winter. Thus, the balancing time in winter was enough to maximize UV benefits and minimize UV risks.

Wavelength Dependence of Solar Flare Irradiation and its Influence on the Thermosphere

Science.gov (United States)

Huang, Yanshi; Richmond, Arthur D.; Deng, Yue; Qian, L.; Solomon, S.; Chamberlin, P.

2012-01-01

The wavelength dependence of solar flare enhancement is one of the important factors determining how the Thermosphere-Ionosphere (T-I) system response to flares. To investigate the wavelength dependence of solar flare, the Flare Irradiance Spectral Model (FISM) has been run for 34 X-class flares. The results show that the percentage increases of solar irradiance at flare peak comparing to pre-flare condition have a clear wavelength dependence. In the wavelength range between 0 - 195 nm, it can vary from 1% to 10000%. The solar irradiance enhancement is largest ( 1000%) in the XUV range (0 - 25 nm), and is about 100% in EUV range (25 - 120 nm). The influence of different wavebands on the T-I system during the October 28th, 2003 flare (X17.2-class) has also been examined using the latest version of National Center for Atmospheric Research (NCAR) Thermosphere- Ionosphere-Electrodynamics General Circulation Model (TIE-GCM). While the globally integrated solar energy deposition is largest in the 0 - 14 nm waveband, the impact of solar irradiance enhancement on the thermosphere at 400 km is largest for 25 - 105 nm waveband. The effect of 122 - 195 nm is small in magnitude, but it decays slowly.

Luteolin as reactive oxygen generator by X-ray and UV irradiation

Science.gov (United States)

Toyama, Michiru; Mori, Takashi; Takahashi, Junko; Iwahashi, Hitoshi

2018-05-01

Non-toxic X-ray-responsive substances can be used in the radiosensitization of cancer, like porphyrin mediated radiotherapy. However, most X-ray-responsive substances are toxic. To find novel non-toxic X-ray-responsive substances, we studied the X-ray and UV reactivity of 40 non-toxic compounds extracted from plants. Dihydroethidium was used as an indicator to detect reactive oxygen species (ROS) generated by the compounds under X-ray or UV irradiation. We found that 13 of the investigated compounds generated ROS under X-ray irradiation and 17 generated ROS under UV irradiation. Only 4 substances generated ROS under both X-ray and UV. In particular, luteolin exhibited the highest activity among the investigated compounds; therefore, the ROS generated by luteolin were thoroughly characterized. To identify the ROS, we employed a combination of ROS detection reagents and their quenchers. O2·- generation by luteolin was monitored using dihydroethidium and superoxide dismutase (as an O2·- quencher). OH· and 1O2 generation was determined using aminophenyl fluorescein with ethanol (OH· quencher) and Singlet Oxygen Sensor Green® with NaN3 (1O2 quencher), respectively. Generation of O2·- under X-ray and UV irradiation was observed; however, no OH· or 1O2 was detected. The production of ROS from luteolin is surprising, because luteolin is a well-known antioxidant.

Structure and properties of UV-irradiated LLDPE and alloy of PA66 and the irradiated LLDPE

International Nuclear Information System (INIS)

Ran Qianping; Zou Hua; Wu Shishan; Shen Jian

2006-01-01

Some oxygen-containing groups such as C=O, C-O and -OH were introduced onto linear low-density polyethylene (LLDPE) chains by UV irradiation in air. Their concentration increased with the irradiation time. Crystal shape of the irradiated LLDPE remained an orthorhombic structure, while space of the crystalline plane kept unchanged. The melting temperature and crystallinity decreased due to the LLDPE chain scission into small molecules compound and crystalline defects caused by UV irradiation. Compared with pristine LLDPE, hydrophilicity of the irradiated LLDPE increased due to the introduction of polar oxygen-containing groups, but the tensile strength decreased due to the LLDPE chain degradation and reduction of crystallinity. The temperature of initial weight loss of the irradiated LLDPE was lower than that of pristine LLDPE. An alloy of PA66 and the irradiated LLDPE (irradiated PA66/LLDPE) was prepared by melting blend at 260-270 degree C. Compared to non-irradiated PA66/LLDPE alloy, dispersion of LLDPE particles in the irradiated PA66/LLDPE alloy and interfacial interactions between the components were markedly improved. Therefore, tensile strength and impact strength of the irradiated PA66/ LLDPE were higher than those of the control. (authors)

UV-B-irradiation effect on growth reactions of phytopathogenic fungus fusarium solani

International Nuclear Information System (INIS)

Gushcha, M.Yi.; Dyachenko, A.Yi.; Dmitryijev, O.P.

2002-01-01

The UV-B irradiation effect on spore germination and hyphae growth of phythopathogenic fungus Fusarium solani was studied. Spores irradiation by small doses of 0,1 - 1,0 kJ/m 2 results in growth stimulation of primary hyphae. Adaptive effect of UV-B small doses for fungi was shown. Preliminary irradiation in doses of 0,1 - 0,5 kJ/m 2 increased spore radioresistance and diminished the effect of the next damaging dose

The influence of dose distributions on the results of UV-biodosimetry

International Nuclear Information System (INIS)

Cabaj, A.; Sommer, R.; Kundi, M.

1996-01-01

Disinfection of drinking water with ultraviolet radiation has become a common method in Austria and in many other countries. The water usually is disinfected in flow through systems with low pressure mercury lamps as UV source, which emit predominantly UV radiation with wavelength 253.7 nm. Because of varying residence times of microorganizms and the special distribution of fluence rate in the irradiation volume, caused by different distances from the radiation source, by absorption of radiation in the water and by reflexion at the walls of the reactor, the microorganizms passing through in a turbulent flow, receive different fluences. In Austria UV-disinfection plants for drinking water must deliver a minimal dose of 400 Jm -2 for radiation of wavelength 253.7 nm. The fulfillment of this demand is proved during type testing. As dosimeter suspensions of bacterial spores are used whose UV-susceptibility has to be measured in a laboratory irradiation device. The dose, determined in this way, is called Reduction Equivalent Dose'. (author)

Protective and therapeutic effects of fucoxanthin against sunburn caused by UV irradiation

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Mio Matsui

2016-09-01

Full Text Available Mild exposure to ultraviolet (UV radiation is also harmful and hazardous to the skin and often causes a photosensitivity disorder accompanied by sunburn. To understand the action of UV on the skin we performed a microarray analysis to isolate UV-sensitive genes. We show here that UV irradiation promoted sunburn and downregulated filaggrin (Flg; fucoxanthin (FX exerted a protective effect. In vitro analysis showed that UV irradiation of human dermal fibroblasts caused production of intracellular reactive oxygen species (ROS without cellular toxicity. ROS production was diminished by N-acetylcysteine (NAC or FX, but not by retinoic acid (RA. In vivo analysis showed that UV irradiation caused sunburn and Flg downregulation, and that FX, but not NAC, RA or clobetasol, exerted a protective effect. FX stimulated Flg promoter activity in a concentration-dependent manner. Flg promoter deletion and chromatin immunoprecipitation analysis showed that caudal type homeo box transcription factor 1 (Cdx1 was a key factor for Flg induction. Cdx1 was also downregulated in UV-exposed skin. Therefore, our data suggested that the protective effects of FX against UV-induced sunburn might be exerted by promotion of skin barrier formation through induction of Flg, unrelated to quenching of ROS or an RA-like action.

Local gene expression changes after UV-irradiation of human skin.

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Benjamin Weinkauf

Full Text Available UV-irradiation is a well-known translational pain model inducing local inflammation and primary hyperalgesia. The mediators and receptor proteins specifically contributing to mechanical or heat hyperalgesia are still unclear. Therefore, we irradiated buttock skin of humans (n = 16 with 5-fold MED of UV-C and assessed the time course of hyperalgesia and axon reflex erythema. In parallel, we took skin biopsies at 3, 6 and 24 h after UVC irradiation and assessed gene expression levels (RT-PCR of neurotrophins (e.g. NGF, BDNF, GDNF, ion channels (e.g. NaV1.7, TRPV1, inflammatory mediators (e.g. CCL-2, CCL-3 and enzymes (e.g. PGES, COX2. Hyperalgesia to mechanical impact (12 m/s and heat (48 °C stimuli was significant at 6 h (p<0.05 and p<0.01 and 24 h (p<0.005 and p<0.01 after irradiation. Axon reflex erythema upon mechanical and thermal stimuli was significantly increased 3 h after irradiation and particularly strong at 6 h. A significant modulation of 9 genes was found post UV-C irradiation, including NGF (3, 6, 24 h, TrkA (6, 24 h, artemin, bradykinin-1 receptor, COX-2, CCL-2 and CCL-3 (3 and 6 h each. A significant down-regulation was observed for TRPV1 and iNOS (6, 24 h. Individual one-to-one correlation analysis of hyperalgesia and gene expression revealed that changes of Nav1.7 (SCN9A mRNA levels at 6 and 24 h correlated to the intensity of mechanical hyperalgesia recorded at 24 h post UV-irradiation (Pearson r: 0.57, p<0.04 and r: 0.82, p<0.001. Expression of COX-2 and mPGES at 6 h correlated to the intensity of heat-induced erythema 24 h post UV (r: 0.57, p<0.05 for COX-2 and r: 0.83, p<0.001 for PGES. The individual correlation analyses of functional readouts (erythema and pain response with local expression changes provided evidence for a potential role of Nav1.7 in mechanical hyperalgesia.

Stability of carotenoids toward UV-irradiation in hexane solution

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DRAGAN CVETKOVIC

2008-01-01

Full Text Available The stabilities of four selected carotenoids dissolved in hexane, two carotenes and two xanthophylls, toward UV-irradiation of three different ranges (UV-A, UV-B and UV-C were studied in this work. The carotenoids underwent bleaching via a probable free radical mediated mechanism following first-order kinetics. The bleaching rates were highly dependent on the input of the involved photons and, although not consistently, on the chemical structures of the investigated compounds. For the two xanthophylls, a possible role of oxygen associated with their bleaching cannot be neglected.

UV-irradiation potentiates the antimutagenicity of p-aminobenzoic and p-aminosalicylic acids in Salmonella typhimurium

International Nuclear Information System (INIS)

Gichner, T.; Baburek, I.; Veleminsky, J.; Kappas, A.

1991-01-01

UV-irradiation (254 nm, 10 or 20 J/cm 2 ) of p-aminobenzoic acid (PABA) and p-aminosalicylic acid (NaPAS) potentiated their antimuta-genicity towards N-methyl-N'-nitro-N-nitrosoguanide metagenesis in Salmonella typhimurium. Their inhibitory action towards the formation of mutagen N-methyl-N-mitrosourea from the nitrosation mixture of N-methylurea and nitrite was also increased by UV-irradiation. In contrast, UV-irradiated PABA exhibited no inhibitory effects towards the mutagenicity of sodium azide or 3-azidoglycerol. Neither PABA nor NaPAS not their UV-irradiation products were themselves mutagenic in the Ames assay. 13 refs.; 5 tabs

Kinetic study of UV-irradiated amorphous sulfur by EPR spectroscopy

International Nuclear Information System (INIS)

El Mkami, H.; Smith, G.M.

2005-01-01

Electron paramagnetic resonance (EPR) spectroscopy is used to investigate UV-irradiation damage in amorphous sulfur by examining post-irradiation kinetics as a function of UV-exposure time. The kinetic study is described by first-order concurrent reactions where the sulfur, as reactant, undergoes two parallel processes leading to the formation of two distinct defects called S 1 * and S 2 *. The temperature dependence of the EPR intensities of the signals, related to these defects, is used in the kinetic study

X-UV lasers and their promising applications

International Nuclear Information System (INIS)

Ros, D.

2004-01-01

The author reviews 30 years of research and achievements concerning X-UV lasers. Typical features of X-UV lasers are: a large number of photons emitted per impulse (between 10 12 and 10 14 ) and very short impulses (between 1 and 100 ps). When a crystal is irradiated by a X-UV laser, these features favor new physical processes that did not appear when the irradiation was performed with other X-UV sources like synchrotron radiation for instance. Their high brilliance and coherence properties make them efficient means as irradiating sources or imaging tools. X-UV laser interferometry allows the mapping of a surface at the nano-metric scale without any interaction between the laser beam and the surface. (A.C.)

Transformation of avobenzone in conditions of aquatic chlorination and UV-irradiation.

Science.gov (United States)

Trebše, Polonca; Polyakova, Olga V; Baranova, Maria; Kralj, Mojca Bavcon; Dolenc, Darko; Sarakha, Mohamed; Kutin, Alexander; Lebedev, Albert T

2016-09-15

Emerging contaminants represent a wide group of the most different compounds. They appear in the environment at trace levels due to human activity. Most of these compounds are not yet regulated. Sunscreen UV-filters play an important role among these emerging contaminants. In the present research the reactions of 4-tert-butyl-4'-methoxydibenzoylmethane (avobenzone), the most common UV filter in the formulation of sunscreens, were studied under the combined influence of active chlorine and UV-irradiation. Twenty five compounds were identified by GC/MS as transformation products of avobenzone in reactions of aquatic UV-irradiation and chlorination with sodium hypochlorite. A complete scheme of transformation of avobenzone covering all the semivolatile products is proposed. The identification of the two primary chlorination products (2-chloro-1-(4-tert-butylphenyl)-3-(4-methoxyphenyl)-1,3-propanedione and 2,2-dichloro-1-(4-tert-butylphenyl)-3-(4-methoxyphenyl)-1,3-propanedione) was confirmed by their synthesis and GC/MS and NMR analysis. Although the toxicities of the majority of these products remain unknown substituted chlorinated phenols and acetophenones are known to be rather toxic. Combined action of active chlorine and UV-irradiation results in the formation of some products (chloroanhydrides, chlorophenols) not forming in conditions of separate application of these disinfection methods. Therefore caring for people «well-being» it is of great importance to apply the most appropriate disinfection method. Since the primary transformation products partially resist powerful UV-C irradiation they may be treated as stable and persistent pollutants. Copyright © 2016 Elsevier Ltd. All rights reserved.

Transformation of Saccharomyces cerevisiae with UV-irradiated single-stranded plasmid.

Science.gov (United States)

Zgaga, Z

1991-08-01

UV-irradiated single-stranded replicative plasmids were used to transform different yeast strains. The low doses of UV used in this study (10-75 J/m2) caused a significant decrease in the transforming efficiency of plasmid DNA in the Rad+ strain, while they had no effect on transformation with double-stranded plasmids of comparable size. Neither the rev3 mutation, nor the rad18 or rad52 mutations influenced the efficiency of transformation with irradiated single-stranded plasmid. However, it was found to be decreased in the double rev3 rad52 mutant. Extracellular irradiation of plasmid that contains both URA3 and LEU2 genes (psLU) gave rise to up to 5% Leu- transformants among selected Ura+ ones in the repair-proficient strain. Induction of Leu- transformants was dose-dependent and only partially depressed in the rev3 mutant. These results suggest that both mutagenic and recombinational repair processes operate on UV-damaged single-stranded DNA in yeast.

Reductone effect on UV-irradiated starved E. coli cells

International Nuclear Information System (INIS)

Felzenszwalb, I.; Gomes, R.A.

1982-01-01

A starvation-induced resistence enhancement (SIRE) to UV and reductone treatments was observed in repair-profient E. coli cells. The UV-reductone positive interaction, which is possibly related to excision repair mechanisms, was not modified by prestarvation when all cells in culture had completed their round of DNA replication. In irradiated prestarved reductone-treated cells, a decrease in the DNA degradation rate was detected after the removal of reductone and the induction of a lower number of DNA single-strand breaks. The induction kinectics of DNA single-strand breaks in prestarved UV-irradiated and the repair kinetics of these lesions are slower than in non-starved cells. The resistance enhancement demonstrated under these conditions could be justified either by the generation of fewer doubles strand breaks during repair or by the possibility of repair of these lesions. (Author) [pt

EFFECT OF UV IRRADIATION ON THE DYEING OF COTTON FABRIC WITH REACTIVE BLUE 204

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ROŞU Liliana

2017-05-01

Full Text Available Reactive dyes are synthetic organic compounds used on a wide scale in textile industry, for painting materials of different types and compositions (e.g. 100% cotton, wool, natural satin, viscose, synthetic fibres. Reactive dyes are solid compounds (powders completely water soluble at normal temperature and pressure conditions. Their structures contain chromophore groups, which generate colour, and auxochrome groups, which determine the compounds water solubility and the capacity to fix to the textile fiber. Such organic compounds absorb UV-Vis radiations at specific wavelengths, corresponding to maximum absorbtion peaks, in both solution and dyed fiber. The human organism, through the dyed clothing, comes in direct contact with those dyes which can undergo modifications once exposed to UV radiations, having the posibility to reach the organism via cutanated transport. As it is known, the provoked negative effects are stronger during summer when UV radiations are more intense and in order to reduce their intensity dark coloured clothing is avoided. Dyes can be transformed in compounds which are easily absorbed into the skin. Some of these metabolites can be less toxic than the original corresponding dye, whilst others, such as free radicals, are potentially cancerous. Knowledge of the biological effects of the organic dyes, reactive dyes in particular, correlated with their structural and physical characteristics, permanently consists an issue of high scientific and practical interest and its solution may contribute in the diminishing of risk factors and improving of population health. UV radiation influence on the structural and colour modifications of textile materials were studied. Colour modifications are due to structural changes in aromatic and carbonil groups. In most cases photo-oxidative processes were identified in the dye structure. Dyeing was performed using non-irradiated and irradiated cotton painted with reactive blue dye 204.

Feeding response of the silkworm, Bombyx mori, to UV irradiation of mulberry leaves

International Nuclear Information System (INIS)

Yazawa, M.; Shimizu, T.; Hirao, T.

1992-01-01

Ultraviolet irradiation of mulberry leaves caused a reduced feeding response in Bombyx mori larvae (ca. 22% reduction in consumption as compared with control). Sucrose content of the foliage decreased after exposure to UV irradiation (0.5 mW/cm 2 ) for 1 hr. Electrophysiological responses of the sensilla styloconica-I to sucrose concentration (ca. 0-80 mg/g) showed a reduced response to UV-irradiated foliage when compared with the control. From feeding, gustatory, and electrophysiological responses, as well as the measurement of sucrose contents of the leaves, we concluded that the reduced feeding response to UV-irradiated leaves is due to the reduced sucrose content of the mulberry leaves, thus reducing pleogostimulatory levels

The effect of UV irradiation on the early development of silkworm embryos, (2)

International Nuclear Information System (INIS)

Kobayashi, Yoshihiro

1981-01-01

The development of silkworm eggs irradiated with UV was compared with that of normal eggs. When the eggs were irradiated with UV from the lateral side immediately after oviposition, development was decelerated, but the germ band was produced. The side of the germ band that was irradiated with UV was abnormal with holes, but the opposite side was hole-free and normal. The normal half of the germ band splits longitudinally, but developed along with the abnormal half to form various malformations. When the eggs were irradiated from the ventral side, the ventral part of the germ band was abnormal at the early stage, the germ band did not concentrate to one place, and produced the half-embryos longitudinally divided by the median line. The UV irradiation at the beginning of the blastoderm stage produced similar results. In the areas irradiated by UV, cleavage nuclei invaded into the surrounding protoplasm, and mitotic figures were observed, but the cell number did not increase even with the advance of development unlike normal cells, whereas the sizes of the cells, their nuclei and nucleoli were enlarged, and intercellular space widened so that the cells were no longer in close contact. The germ band cells produced in the non-irradiated area were normal. The above results suggest that when either the protoplasm or the nucleus of a silkworm egg is damaged by UV, the effect first appears as the inhibition of cell division in the germ band, and as the enlargement of the cell, nucleus and nucleoli. It is presumed that this induces the subsequent inhibition of cell differentiation or abnormalities. (Kaihara, S.)

Alignment control of columnar liquid crystals with wavelength tunable CO2 laser irradiation

International Nuclear Information System (INIS)

Monobe, Hirosato; Awazu, Kunio; Shimizu, Yo

2008-01-01

Infrared-induced alignment change with wavelength tunable CO 2 laser irradiation for columnar liquid crystal domains was investigated for a liquid crystalline triphenylene derivative. A uniformly aligned alignment change of domains was observed when a chopped linearly polarized infrared laser light corresponding to the wavelength of the aromatic C-O-C stretching vibration band (9.65 μm) was irradiated. The results strongly imply that the infrared irradiation is a possible technique for device fabrication by use of columnar mesophase as a liquid crystalline semiconductor

Post-irradiation replication and repair in uv-irradiated cells of Proteus mirabilis depends on protein synthesis and a functioning rec/sup +/ gene

Energy Technology Data Exchange (ETDEWEB)

Hofemeister, J [Akademie der Wissenschaften der DDR, Gatersleben. Zentralinstitut fuer Genetik und Kulturpflanzenforschung

1977-02-28

The amount of and the molecular weight of newly synthesized DNA (piDNA) as well as its repair after uv irradiation in excision-proficient strains of P.mirabilis and E.coli K12 have been compared. A fraction of post-replication repair (PRR) in P.mirabilis is found to be dependent on de novo protein synthesis after uv irradiation. Pre-irradiation by uv and pre-treatment with nalidixic acid increase the efficiency of post-irradiation replication and PRR even in the presence of chloramphenicol. An inducible repair function in P.mirabilis is supposed to stimulate post-irradiation replication and repair.

Loss of photoreactivation in UV-irradiated cultured fish cells under different conditions

Energy Technology Data Exchange (ETDEWEB)

Mano, Y.; Kator, K.; Egami, N. (Tokyo Univ. (Japan). Faculty of Science)

1982-05-01

CAF-MM1 cells derived from a goldfish have photoreactivability for the damage induced by ultraviolet light. When UV-irradiated cells were incubated in the dark at 26/sup 0/C, the longest interval in which photoreactivation (PR) was observed, measured by colony formation technique, was about 30h after the UV irradiation. However, if the cells were incubated at 20/sup 0/C, the effective time was prolonged. Since each time appeared to correspond to the doubling time of the cells at each temperature, the loss of photoreactivability is suggested to be closely related to cell growth or progression of cell cycle. The loss of PR was not observed in the cells held in confluence up to 48h after UV irradiation. Photoreactivating enzyme in growing CAF-MM1 cells incubated in the dark for 24h after UV irradiation was shown to be active, so that it is not possible that the cause of the loss of PR is change in the activity of photoreactivating enzyme.

Photochemical oxidation of short-chain polychlorinated n-alkane mixtures using H2O2/UV and the photo-Fenton reaction

OpenAIRE

Ken J. Friesen; Taha M. El-Morsi; Alaa S. Abd-El-Aziz

2004-01-01

The photochemical oxidation of a series of short-chain polychlorinated n-alkane (PCA) mixtures was investigated using H2O2/UV and modified photo-Fenton conditions (Fe3+/H2O2/UV) in both Milli-Q and lake water. All PCA mixtures, including chlorinated (Cl5 to Cl8) decanes, undecanes, dodecanes and tridecanes degraded in 0.02 M H2O2/UV at pH 2.8 in pure water, with 80±4% disappearance after 3 h of irradiation using a 300 nm light source. Degradation was somewhat enhanced under similar conditions...

Thermal Degradation and Damping Characteristic of UV Irradiated Biopolymer

Directory of Open Access Journals (Sweden)

Anika Zafiah M. Rus

2015-01-01

Full Text Available Biopolymer made from renewable material is one of the most important groups of polymer because of its versatility in application. In this study, biopolymers based on waste vegetable oil were synthesized and cross-link with commercial polymethane polyphenyl isocyanate (known as BF. The BF was compressed by using hot compression moulding technique at 90°C based on the evaporation of volatile matter, known as compress biopolymer (CB. Treatment with titanium dioxide (TiO2 was found to affect the physical property of compressed biopolymer composite (CBC. The characterization of thermal degradation, activation energy, morphology structure, density, vibration, and damping of CB were determined after UV irradiation exposure. This is to evaluate the photo- and thermal stability of the treated CB or CBC. The vibration and damping characteristic of CBC samples is significantly increased with the increasing of UV irradiation time, lowest thickness, and percentages of TiO2 loading at the frequency range of 15–25 Hz due to the potential of the sample to dissipate energy during the oscillation harmonic system. The damping property of CBC was improved markedly upon prolonged exposure to UV irradiation.

The co-application effects of fullerene and ascorbic acid on UV-B irradiated mouse skin

International Nuclear Information System (INIS)

Ito, Shinobu; Itoga, Kazuyoshi; Yamato, Masayuki; Akamatsu, Hirohiko; Okano, Teruo

2010-01-01

The role of fullerene as a pro-oxidant or anti-oxidant in Ultraviolet B ray (UV-B)-induced disorders in mouse skin was investigated. Fullerene gave no photo-toxic effect to UV-B-irradiated mouse skin. Since erythema was concentrated at the pore circumference in a UV-B irradiation experiment in mouse skin, the sebaceous gland pairs was strongly implicated as a site for the generation of reactive oxygen species (ROS). In a histological evaluation of the skin stained with CH 3 MDFDA (ROS index) and YO-Pro-1 (apoptosis index), the fluorescence intensity of a sebaceous gland significantly increased with UV-B irradiation. With the application of fullerene to UV-irradiated mouse skin, no toxicity was recognized in comparison with the control, and erythema, the ROS index, and the apoptosis index decrease with the application of fullerene. Ascorbyl radical (AA·) increased with the application of ascorbate (AA) to UV-B-irradiated mouse skin, and AA· decreased with the application of fullerene. The co-application of AA and fullerene, which suppressed AA· in vitro, significantly suppressed erythema, and also suppressed both the ROS index and apoptosis index in mouse skin after UV-B irradiation. In both mouse skin at 48 h after UV-B irradiation and in an attempt to reproduce this phenomenon artificially in vitro, a similar high AA· peak (AA·/H· > 4) was observed in electron spin resonance (ESR) charts. The binding of fullerene with AA impairs the Fenton reaction between AA and Fe-protein based on the observation of ascorbate-specific UV absorption and a linear equation for the calibration curve. Therefore, fullerene may impair the intercalation of AA to a heme pocket by binding with AA. These results suggest that the co-application of AA and fullerene is effective against oxidative skin damage caused by UV-B irradiation, and the development of an AA· inhibitor such as fullerene should be useful for reducing organ damage associated with Fe-protein oxidation.

Protective and therapeutic effects of fucoxanthin against sunburn caused by UV irradiation.

Science.gov (United States)

Matsui, Mio; Tanaka, Kosuke; Higashiguchi, Naoki; Okawa, Hisato; Yamada, Yoichi; Tanaka, Ken; Taira, Soichiro; Aoyama, Tomoko; Takanishi, Misaki; Natsume, Chika; Takakura, Yuuki; Fujita, Norihisa; Hashimoto, Takeshi; Fujita, Takashi

2016-09-01

Mild exposure to ultraviolet (UV) radiation is also harmful and hazardous to the skin and often causes a photosensitivity disorder accompanied by sunburn. To understand the action of UV on the skin we performed a microarray analysis to isolate UV-sensitive genes. We show here that UV irradiation promoted sunburn and downregulated filaggrin (Flg); fucoxanthin (FX) exerted a protective effect. In vitro analysis showed that UV irradiation of human dermal fibroblasts caused production of intracellular reactive oxygen species (ROS) without cellular toxicity. ROS production was diminished by N-acetylcysteine (NAC) or FX, but not by retinoic acid (RA). In vivo analysis showed that UV irradiation caused sunburn and Flg downregulation, and that FX, but not NAC, RA or clobetasol, exerted a protective effect. FX stimulated Flg promoter activity in a concentration-dependent manner. Flg promoter deletion and chromatin immunoprecipitation analysis showed that caudal type homeo box transcription factor 1 (Cdx1) was a key factor for Flg induction. Cdx1 was also downregulated in UV-exposed skin. Therefore, our data suggested that the protective effects of FX against UV-induced sunburn might be exerted by promotion of skin barrier formation through induction of Flg, unrelated to quenching of ROS or an RA-like action. Copyright © 2016 The Authors. Production and hosting by Elsevier B.V. All rights reserved.

The influence of urban area opacity on biologically active UV-B irradiance

Science.gov (United States)

Chubarova, Nataly; Rozental', Victor

2013-04-01

The study of UV irradiance changes in urban area is an essential problem due to the significant effect of UV irradiance on human health which can be positive (vitamin D synthesis) and negative (erythema, skin cancer, eye damage). According to the results of several experiments within the Moscow megacity we studied the effects of urban area opacity on the different types of biologically active UV-B irradiance on the base of a specially developed mobile photometric complex snd additional measurements of the urban opacity by Nikon Fisheye Converter FC-E8. We analyzed both the level of erythemally-active irradiance and the UV eye damaging radiation using the broadband UVB-1 YES pyranometer calibrated against ultraviolet spectroradiometer Bentham DTM-300 of the Medical University of Innsbruck (courtesy of Dr. M.Blumthaler). In order to estimate the effects of the urban opacity the measurements were normalized on similar measurements at the Meteorological Observatory of Moscow State University with zero opacity. This ratio is defined as an urban radiative transmittance (URT). Different atmospheric conditions were considered. In cloudy conditions the effect of opacity on URT is much less than that in conditions when the sun disk is open from clouds. We revealed some spectral features in transmittance of biologically active UV-B irradiance which is characterized by higher URT variations in overcast cloudy conditions due to more intensive scattering and smaller direct solar radiation component. In the absence of cloudiness the effect of opacity was studied for open and screening solar disk conditions. We obtained much higher URT in UVB spectral region compared with that for total solar irradiance for screening solar disk conditions with a significant URT dependence on the opacity only in UVB spectral region. No URT dependence was obtained for total solar irradiance in these conditions. Some model calculations were fulfilled to match the experimental results.

Improved osteoblast response to UV-irradiated PMMA/TiO2 nanocomposites with controllable wettability.

Science.gov (United States)

Shayan, Mahdis; Jung, Youngsoo; Huang, Po-Shun; Moradi, Marzyeh; Plakseychuk, Anton Y; Lee, Jung-Kun; Shankar, Ravi; Chun, Youngjae

2014-12-01

Osteoblast response was evaluated with polymethylmethacrylate (PMMA)/titanium dioxide (TiO2) nanocomposite thin films that exhibit the controllable wettability with ultraviolet (UV) treatment. In this study, three samples of PMMA/TiO2 were fabricated with three different compositional volume ratios (i.e., 25/75, 50/50, and 75/25) followed by UV treatment for 0, 4, and 8 h. All samples showed the increased hydrophilicity after UV irradiation. The films fabricated with the greater amount of TiO2 and treated with the longer UV irradiation time increased the hydrophilicity more. The partial elimination of PMMA on the surface after UV irradiation created a durable hydrophilic surface by (1) exposing higher amount of TiO2 on the surface, (2) increasing the hydroxyl groups on the TiO2 surface, and (3) producing a mesoporous structure that helps to hold the water molecules on the surface longer. The partial elimination of PMMA on the surface was confirmed by Fourier transform infrared spectroscopy. Surface profiler and atomic force microscopy demonstrated the increased surface roughness after UV irradiation. Both scanning electron microscopy and energy-dispersive X-ray spectroscopy demonstrated that particles containing calcium and phosphate elements appeared on the 8 h UV-treated surface of PMMA/TiO2 25/75 samples after 4 days soaking in Dulbecco's Modified Eagle Medium. UV treatment showed the osteoblast adhesion improved on all the surfaces. While all UV-treated hydrophilic samples demonstrated the improvement of osteoblast cell adhesion, the PMMA/TiO2 25/75 sample after 8 h UV irradiation (n = 5, P value = 0.000) represented the best cellular response as compared to other samples. UV-treated PMMA/TiO2 nanocomposite thin films with controllable surface properties represent a high potential for the biomaterials used in both orthopedic and dental applications.

Change of properties of erythrocytes membranes in UV-irradiated blood

International Nuclear Information System (INIS)

Gromov, A.E.; Vetosh, A.N.; Nikonchuk, N.P.; Perelygin, V.G.; Ruzanov, I.B.

1986-01-01

An increase in erythrocyte membrane permeability for gases, decrease in erythrocyte thermal stability and activation of membrane transport systems after autotransfusion of UV-irradiated blood are ascertained. The data obtained testify to the fact that the greatest changes in membranes take place not directly under irradiation but after the introduction of irradiated blood to the organism

Influence of the UV Environment on the Synthesis of Prebiotic Molecules.

Science.gov (United States)

Ranjan, Sukrit; Sasselov, Dimitar D

2016-01-01

Ultraviolet radiation is common to most planetary environments and could play a key role in the chemistry of molecules relevant to abiogenesis (prebiotic chemistry). In this work, we explore the impact of UV light on prebiotic chemistry that might occur in liquid water on the surface of a planet with an atmosphere. We consider effects including atmospheric absorption, attenuation by water, and stellar variability to constrain the UV input as a function of wavelength. We conclude that the UV environment would be characterized by broadband input, and wavelengths below 204 nm and 168 nm would be shielded out by atmospheric CO2 and water, respectively. We compare this broadband prebiotic UV input to the narrowband UV sources (e.g., mercury lamps) often used in laboratory studies of prebiotic chemistry and explore the implications for the conclusions drawn from these experiments. We consider as case studies the ribonucleotide synthesis pathway of Powner et al. (2009) and the sugar synthesis pathway of Ritson and Sutherland (2012). Irradiation by narrowband UV light from a mercury lamp formed an integral component of these studies; we quantitatively explore the impact of more realistic UV input on the conclusions that can be drawn from these experiments. Finally, we explore the constraints solar UV input places on the buildup of prebiotically important feedstock gasses like CH4 and HCN. Our results demonstrate the importance of characterizing the wavelength dependence (action spectra) of prebiotic synthesis pathways to determine how pathways derived under laboratory irradiation conditions will function under planetary prebiotic conditions.

Alteration of Paramecium candatum germinal nucleus morphology after UV irradiation

Energy Technology Data Exchange (ETDEWEB)

Fokin, S.I. (Leningradskij Gosudarstvennyj Univ. (USSR). Biologicheskij Nauchno-Issledovatel' skij Inst.)

1982-09-01

A study was made on morphologic changes of micronucleus (Mi) after whole-body ultraviolet (UV) irradiation of paramecia as well as after local irradiation of this nucleus or the area of macronucleus (Ma). The whole-body irradiation of its Ma part leads to generative nucleus growth in sizes and chromatin structure change, which is expressed in occurence of large chromatin bodies. Aftereffects of local action on Mi for viable descendants are expressed in nucleus size transformation (usually in reduction), gaining ''comet-shaped'' form and probably in reduction of dna amount. Irradiation of Ma and total effect on cell cause Mi changes of reversible character. All morphologic changes of Mi after local ultraviolet irradiation are conserved in descendants and are not photoreactivated. Possible reasons for this phenomenon are discussed. The results obtained make it possible to speak about different mechanisms of action on Mi in the case of local and whole-body UV irradiation of cell. The effect of irradiated Ma on generative nucleus, but not direct damage of this nucleus is the reason for Mi morphologic reconstruction after whole-body action on paramecium.

Partial replicas of uv-irradiated bacteriophage T4 genomes and their role in multiplicity reactivation

International Nuclear Information System (INIS)

Rayssiguier, C.; Kozinski, A.W.; Doermann, A.H.

1980-01-01

A physicochemical study was made of the replication and transmission of uv-irradiated T4 genomes. The data presented in this paper justify the following conclusions. (i) For both low and high multiplicity of infection there was abundant replication from uv-irradiated parental templates. It exceeded by far the efficiency predicted by the hypothesis that a single lethal hit completely prevents replication of the killed phage DNA: i.e., some dead phage particles must replicate parts of their DNA. (ii) Replication of the uv-irradiated DNA was repetitive as shown by density reversal experiments. (iii) Newly synthesized progeny DNA originating from uv-irradiated templates appeared as significantly shorter segments of the genomes than progeny DNA produced from non-uv-irradiated templates. A good correlation existed between the number of uv hits and the number of random cuts that would be needed to reduce replication fragments to the length observed. (iv) The contribution of uv-irradiated parental DNA among progeny phage in multiplicity reactivation was disposed in shorter subunits than was the DNA from unirradiated parental phage. It is important to emphasize that it was mainly in the form of replicative hybrid. These conclusions appear to justify excluding interparental recombination as a prerequisite for multiplicity reactivation. They lead directly to some form of partial replica hypothesis for multiplicity reactivation

High reflectivity YDH/SiO2 distributed Bragg reflector for UV-C wavelength regime

KAUST Repository

Alias, Mohd Sharizal

2018-02-15

A distributed Bragg reflector (DBR) composed of Y2O3-doped HfO2 (YDH)/SiO2 layers with high reflectivity spectrum centered at a wavelength of ~240 nm is deposited using radio-frequency magnetron sputtering. Before the DBR deposition, optical properties for a single layer of YDH, SiO2, and HfO2 thin films were studied using spectroscopic ellipsometry and spectrophotometry. To investigate the performance of YDH as a material for the high refractive index layer in the DBR, a comparison of its optical properties was made with HfO2 thin films. Due to larger optical bandgap, the YDH thin films demonstrated higher transparency, lower extinction coefficient, and lower absorption coefficient in the UV-C regime (especially for wavelengths below 250 nm) compared to the HfO2 thin films. The deposited YDH/SiO2 DBR consisting of 15 periods achieved a reflectivity higher than 99.9% at the wavelength of ~240 nm with a stopband of ~50 nm. The high reflectivity and broad stopband of YDH/SiO2 DBRs will enable further advancement of various photonic devices such as vertical-cavity surface-emitting lasers, resonant-cavity light-emitting diodes, and resonant-cavity photodetectors operating in the UV-C wavelength regime.

X-ray or UV-ray imaging sensor utilizing optically stimulated luminescence phenomenon in Eu-doped KCl phosphors

International Nuclear Information System (INIS)

Nanto, Hidehito; Murayama, Kazuhiko; Hirai, Yoshiaki; Taniguchi, Shin-ichi; Makamura, Shouichi; Takeuchi, Nozomu.

1993-01-01

An intense OSL with a peak at about 420 [nm] has been observed by stimulating an X-ray or UV-ray irradiated KCl: Eu crystal with F-band light whose wavelength is about 560 [um]. A possible excitation and emission mechanisms for the 420 [um] OSL peak X-ray or UV-ray irradiated sample is proposed. It is found that the OSL intensity is proportional to the X-ray absorbed dose or UV-ray irradiation dose. It is also found that X-ray or UV-ray irradiated KCl; Eu exhibited excellent fading characteristics. These results strongly suggest that the KCl: Eu is one of the most attractive candidates for two-dimensional X-ray or UV-ray imaging sensor utilizing the OSL phenomenon. (J.P.N.)

Assessment of DNA damage and repair in Mycobacterium terrae after exposure to UV irradiation.

Science.gov (United States)

Bohrerova, Z; Linden, K G

2006-11-01

Ultraviolet (UV) irradiation for drinking water treatment was examined for inactivation and subsequent dark and photo-repair of Mycobacterium terrae. UV sources tested were low pressure (monochromatic, 254 nm) and medium pressure (polychromatic UV output) Hg lamps. UV exposure resulted in inactivation, and was followed by dark or photo-repair experiments. Inactivation and repair were quantified utilizing a molecular-based endonuclease sensitive site (ESS) assay and conventional colony forming unit (CFU) viability assay. Mycobacterium terrae was more resistant to UV disinfection compared to many other bacteria, with approximately 2-log reduction at a UV fluence of 10 mJ cm(-2) ; similar to UV inactivation of M. tuberculosis. There was no difference in inactivation between monochromatic or polychromatic UV lamps. Mycobacterium terrae did not undergo detectable dark repair. Photo-repair resulted in recovery from inactivation by approximately 0.5-log in less than 30 min for both UV lamp systems. Mycobacterium terrae is able to photo-repair DNA damage within a short timeframe. The number of pyrimidine dimers induced by UV light were similar for Escherichia coli and M. terrae, however, this similarity did not hold true for viability results. There is no practical difference between UV sources for disinfection or prevention of DNA repair for M. terrae. The capability of M. terrae to photo-repair UV damage fairly quickly is important for wastewater treatment applications where disinfected effluent is exposed to sunlight. Finally, molecular based assay results should be evaluated with respect to differences in the nucleic acid content of the test micro-organism.

DNA repair in gamma-and UV-irradiated Escherichia coli treated with caffeine and acriflavine

International Nuclear Information System (INIS)

Zhestyanikov, V.D.; Savel'eva, G.E.

1978-01-01

A study is made of the postradiation effect of caffeine and acriflavine on the survival rate and DNA repair in E. coli exposed to γ- and UV-radiation. When added to postradiation growth medium caffeine and acriflavine lower the survival rate of γ-irradiated radioresistant strains, B/r and Bsub(s-1)γR, and UV-irradiated UV-resistant strain B/r, and do not appreciably influence the survival of strains that are sensitive to γ- and UV-radiation. The survival rate of UV-irradiated mutant BsUb(s-1) somewhat increases in the presence of caffeine. Caffeine and acriflavine inhibit repair of single-stranded DNA breaks induced in strain B/r by γ-radiation (slow repair) and UV light. Acriflavine arrests a recombination branch of postreplication repair of DNA in E. coli Bsub(s-1)γR Whereas caffeine does not influence this process

Modelling UV irradiances on arbitrarily oriented surfaces: effects of sky obstructions

Directory of Open Access Journals (Sweden)

M. Hess

2008-07-01

Full Text Available A method is presented to calculate UV irradiances on inclined surfaces that additionally takes into account the influence of sky obstructions caused by obstacles such as mountains, houses, trees, or umbrellas. With this method it is thus possible to calculate the impact of UV radiation on biological systems, such as, for instance, the human skin or eye, in any natural or artificial environment. The method, which consists of a combination of radiation models, is explained here and the accuracy of its results is demonstrated. The effect of a natural skyline is shown for an Alpine ski area, where the UV irradiance even on a horizontal surface may increase due to reflection from snow by more than 10 percent. In contrast, in a street canyon the irradiance on a horizontal surface is reduced to 30% in shadow and to about 75% for a position in the sun.

Modelling UV irradiances on arbitrarily oriented surfaces: effects of sky obstructions

Science.gov (United States)

Hess, M.; Koepke, P.

2008-07-01

A method is presented to calculate UV irradiances on inclined surfaces that additionally takes into account the influence of sky obstructions caused by obstacles such as mountains, houses, trees, or umbrellas. With this method it is thus possible to calculate the impact of UV radiation on biological systems, such as, for instance, the human skin or eye, in any natural or artificial environment. The method, which consists of a combination of radiation models, is explained here and the accuracy of its results is demonstrated. The effect of a natural skyline is shown for an Alpine ski area, where the UV irradiance even on a horizontal surface may increase due to reflection from snow by more than 10 percent. In contrast, in a street canyon the irradiance on a horizontal surface is reduced to 30% in shadow and to about 75% for a position in the sun.

Photochemical decomposition of perfluorooctanoic acid in aqueous periodate with VUV and UV light irradiation

International Nuclear Information System (INIS)

Cao, M.H.; Wang, B.B.; Yu, H.S.; Wang, L.L.; Yuan, S.H.; Chen, J.

2010-01-01

The photochemical decomposition of perfluorooctanoic acid (PFOA) in aqueous periodate (IO 4 - ) was investigated under two types of low-pressure mercury lamps: one emits at 254 nm light (UV light) and the other emits both 254 nm and 185 nm light (VUV light). PFOA decomposed efficiently under VUV light irradiation while it decomposed poorly under UV light irradiation. The addition of IO 4 - significantly increased the rate of decomposition and defluorination of PFOA irradiated with UV light whereas it decreased both processes under VUV irradiation. Reactive radical (IO 3 ·) generated by photolysis of IO 4 - initiated the oxidation of PFOA in UV process. Aquated electrons (e aq - ), generated from water homolysis, scavenged IO 4 - resulting in decrease of reactive radical species production and PFOA decomposition. The shorter-chain perfluorocarboxylic acids (PFCAs) formed in a stepwise manner from long-chain PFCAs.

UV irradiation to mouse skin decreases hippocampal neurogenesis and synaptic protein expression via HPA axis activation.

Science.gov (United States)

Han, Mira; Ban, Jae-Jun; Bae, Jung-Soo; Shin, Chang-Yup; Lee, Dong Hun; Chung, Jin Ho

2017-11-14

The skin senses external environment, including ultraviolet light (UV). Hippocampus is a brain region that is responsible for memory and emotion. However, changes in hippocampus by UV irradiation to the skin have not been studied. In this study, after 2 weeks of UV irradiation to the mouse skin, we examined molecular changes related to cognitive functions in the hippocampus and activation of the hypothalamic-pituitary-adrenal (HPA) axis. UV exposure to the skin decreased doublecortin-positive immature neurons and synaptic proteins, including N-methyl-D-aspartate receptor 2 A and postsynaptic density protein-95, in the hippocampus. Moreover, we observed that UV irradiation to the skin down-regulated brain-derived neurotrophic factor expression and ERK signaling in the hippocampus, which are known to modulate neurogenesis and synaptic plasticity. The cutaneous and central HPA axes were activated by UV, which resulted in significant increases in serum levels of corticosterone. Subsequently, UV irradiation to the skin activated the glucocorticoid-signaling pathway in the hippocampal dentate gyrus. Interestingly, after 6 weeks of UV irradiation, mice showed depression-like behavior in the tail suspension test. Taken together, our data suggest that repeated UV exposure through the skin may negatively affect hippocampal neurogenesis and synaptic plasticity along with HPA axis activation.

Irradiation uniformity of spherical targets by multiple uv beams from OMEGA

International Nuclear Information System (INIS)

Beich, W.; Dunn, M.; Hutchison, R.

1984-01-01

Direct-drive laser fusion demands extremely high levels of irradiation uniformity to ensure uniform compression of spherical targets. The assessment of illumination uniformity of targets irradiated by multiple beams from the OMEGA facility is made with the aid of multiple beams spherical superposition codes, which take into account ray tracing and absorption and a detailed knowledge of the intensity distribution of each beam in the target plane. In this report, recent estimates of the irradiation uniformity achieved with 6 and 12 uv beams of OMEGA will be compared with previous measurements in the IR, and predictions will be made for the uv illumination uniformity achievable with 24 beams of OMEGA

Rutin increases critical wavelength of systems containing a single UV filter and with good skin compatibility.

Science.gov (United States)

Peres, D A; de Oliveira, C A; da Costa, M S; Tokunaga, V K; Mota, J P; Rosado, C; Consiglieri, V O; Kaneko, T M; Velasco, M V R; Baby, A R

2016-08-01

Ultraviolet (UV) radiation is responsible for sunburns, skin cancer, photoaging, and the production of reactive oxygen species (ROS). The awareness on preventing these deleterious effects made the use of anti-UVB formulations an important part of population habits; however, despite the availability of several antioxidants capable of ROS scavenging, the pharmaceutical market lacks products associating UV filters with natural compounds of proven efficacy. Here, we investigated the effect of rutin, a flavonoid with antioxidant activity, associated with UVB filters in dermocosmetic preparations. Formulations were assessed through its antioxidant activity, in vitro photoprotective effectiveness, photostability, and in vivo skin tolerance (hydration, transepidermal water loss, and erythema). Samples containing rutin were compatible with the human skin and presented a pronounced antioxidant potential, with scavenging activity values 75% higher than the ones containing only UVB filters. Although rutin could not prevent the sunscreens photodegradation post-irradiation, the bioactive compound significantly increased the formulations critical wavelengths, showing a photoprotective gain, especially in the UVA range. In conclusion, the absorption in the UVA range, coupled with ROS scavenging potential, proved the positive effect of rutin applied to anti-UVB formulations, making this bioactive compound a promising candidate for photoprotection improvement. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Photoreversible UV-inactivation of messenger RNA in an insect embryo (Smittia spec., chironomidae, diptera)

International Nuclear Information System (INIS)

Jaeckle, H.; Kalthoff, K.

1980-01-01

Smittia embryos were UV-irradiated during intravitelline cleavage while nuclei are heavily shielded by yolk-rich cytoplasm and do not synthesize detectable amounts of RNA. Irradiation at 265, 285 and 295 nm wavelength caused biological inactivation, and pyrimidine dimer formation in maternal RNA. Marked effects on protein synthesis were also observed: (1) the overall rate of 35 S-methionine incorporation in vivo was reduced to less than half of the normal rate, (2) two dimensional gel electrophoresis revealed quantitative variations in the synthetic rate of some polypeptides and the appearance of new ones in UV-irradiated embryos, (3) translation of polyadenylated RNA from Smittia embryos in a cell-free system was inhibited by UV-irradiation in vivo, (4) the apparent degradation during early embryogenesis, of maternal polyadenylated RNA was retarded in UV-irradiated embryos. Exposure to light (400 nm) after UV caused partial photoreversal of all UV effects observed. This is the first data showing that animal mRNA, after UV-irradiation, can be photoreactivated in vivo. The results also strongly suggest that the photorepairable lesions consist of pyrimidine dimers generated in a photosensitized reaction. (author)

Short-wavelength luminescence in Ho{sup 3+}-doped KGd(WO{sub 4}){sub 2} crystals

Energy Technology Data Exchange (ETDEWEB)

Malinowski, M., E-mail: m.malinowski@elka.pw.edu.p [Institute of Microelectronics and Optoelectronics, Koszykowa 75, 00-662 Warsaw (Poland); Kaczkan, M.; Stopinski, S.; Piramidowicz, R. [Institute of Microelectronics and Optoelectronics, Koszykowa 75, 00-662 Warsaw (Poland); Majchrowski, A. [Institute of Applied Physics, Military University of Technology, Kaliskiego 2, 00-908 Warsaw (Poland)

2009-12-15

Emissions from the high-lying excited states, energy transfer and upconversion processes are investigated in Ho{sup 3+}-activated KGd(WO{sub 4}){sub 2} crystal. The spectral assignment based on time-resolved emission spectra allowed to identify various near ultra-violet (UV), blue and green emissions starting from the excited {sup 3}H{sub 5}, {sup 5}G{sub 4}, {sup 5}G{sub 5}, {sup 5}F{sub 3} and {sup 5}S{sub 2} levels. The temporal behavior of these transitions after pulsed excitation was analyzed as a function of temperature and holmium ions concentration. The shortening and nonexponentiality of the decays, observed with increasing activator concentrations, indicated cross-relaxation (CR) among the Ho{sup 3+} ions. Cross-relaxation rates were experimentally determined as a function of activator concentration and used to evaluate the values of the nearest-neighbor trapping rates X{sub 01} and to model the decays. It was observed that KGW, despite higher than in YAG maximum phonon energy of about 900 cm{sup -1}, is more efficient short-wavelength emitter than YAG. Examples of the excited-state absorption (ESA) and energy transfer (ET) mechanisms responsible for the upconverted, short-wavelength emissions were identified by analyzing fluorescence dynamics and possible energy resonances.

Ultraviolet-C irradiation for inactivation of viruses in foetal bovine serum.

Science.gov (United States)

Vaidya, Vivek; Dhere, Rajeev; Agnihotri, Snehal; Muley, Ravindra; Patil, Sanjay; Pawar, Amit

2018-07-05

Foetal Bovine Serum (FBS) and porcine trypsin are one of the essential raw materials used in the manufacturing of cell culture based viral vaccines. Being from animal origin, these raw materials can potentially contaminate the final product by known or unknown adventitious agents. The issue is more serious in case of live attenuated viral vaccines, where there is no inactivation step which can take care of such adventitious agents. It is essential to design production processes which can offer maximum viral clearance potential for animal origin products. Ultraviolet-C irradiation is known to inactivate various adventitious viral agents; however there are limited studies on ultraviolet inactivation of viruses in liquid media. We obtained a recently developed UVivatec ultraviolet-C (UV-C) irradiation based viral clearance system for evaluating its efficacy to inactivate selected model viruses. This system has a unique design with spiral path of liquid allowing maximum exposure to UV-C light of a short wavelength of 254 nm. Five live attenuated vaccine viruses and four other model viruses were spiked in tissue culture media and exposed to UV-C irradiation. The pre and post UV-C irradiation samples were analyzed for virus content to find out the extent of inactivation of various viruses. These experiments showed substantial log reduction for the majority of the viruses with few exceptions based on the characteristics of these viruses. Having known the effect of UV irradiation on protein structure, we also evaluated the post irradiation samples of culture media for growth promoting properties using one of the most fastidious human diploid cells (MRC-5). UV-C exposure did not show any notable impact on the nutritional properties of culture media. The use of an UV-C irradiation based system is considered to be promising approach to mitigate the risk of adventitious agents in cell culture media arising through animal derived products. Copyright © 2018 Elsevier Ltd. All

Determination of 2-alkylcyclobutanones in ultraviolet light-irradiated fatty acids, triglycerides, corn oil, and pork samples: Identifying a new source of 2-alkylcyclobutanones.

Science.gov (United States)

Meng, Xiangpeng; Chan, Wan

2017-02-15

Previous studies have established that 2-alkylcyclobutanones (2-ACBs) are unique radiolytic products in lipid-containing foods that could only be formed through exposure to ionizing radiation, but not by any other means of physical/heat treatment methods. Therefore, 2-ACBs are currently the marker molecules required by the European Committee for Standardization to be used to identify foods irradiated with ionizing irradiation. Using a spectrum of state-of-the-art analytical instruments, we present in this study for the first time that the generation of 2-ACBs was also possible when fatty acids and triglycerides are exposed to a non-ionizing, short-wavelength ultraviolet (UV-C) light source. An irradiation dosage-dependent formation of 2-ACBs was also observed in UV-C irradiated fatty acids, triglycerides, corn oil, and pork samples. With UV-C irradiation becoming an increasingly common food treatment procedure, it is anticipated that the results from this study will alert food scientists and regulatory officials to a potential new source for 2-ACBs. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of UV irradiation on the shear bond strength of titanium with segmented polyurethane through gamma-mercapto propyl trimethoxysilane.

Science.gov (United States)

Sakamoto, Harumi; Hirohashi, Yohei; Doi, Hisashi; Tsutsumi, Yusuke; Suzuki, Yoshiaki; Noda, Kazuhiko; Hanawa, Takao

2008-01-01

The objective of this study was to investigate the effect of UV irradiation on shear bond strength between a titanium (Ti) and a segmented polyurethane (SPU) composite through gamma-mercapto propyl trimethoxysilane (gamma-MPS). To this end, the shear bond strength of Ti/SPU interface of Ti-SPU composite under varying conditions of ultraviolet ray (UV) irradiation was evaluated by a shear bond test. The glass transition temperatures of SPU with and without UV irradiation were also determined using differential scanning calorimetry. It was found that the shear bond strength of Ti/SPU interface increased with UV irradiation. However, excessive UV irradiation decreased the shear bond strength of Ti/SPU interface. Glass transition temperature was found to increase during 40-60 seconds of UV irradiation. In terms of durability after immersion in water at 37 degrees C for 30 days, shear bond strength was found to improve with UV irradiation. In conclusion, UV irradiation to a Ti-SPU composite was clearly one of the means to improve the shear bond strength of Ti/SPU interface.

The alteration of Paramecium candatum germinal nucleus morphology after UV irradiation

International Nuclear Information System (INIS)

Fokin, S.I.

1982-01-01

A study was made on morphologic changes of micronucleus (Mi) after whole-body ultraviolet (UV) irradiation of paramecia as well as after local irradiation of this nucleus or the area of macronucleus (Ma). The whole-body irradiation of its Ma part leads to generative nucleus growth in sizes and chromatin structure change, which is expressed in occurence of large chromatin bodies. Aftereffects of local action on Mi for viaable descendants are expressed in nucleus size transformation (usually in reduction), gaining ''comet-shaped'' form and probably in reduction of dna amount. Irradiation of Ma and total effect on cell cause Mi changes of reversible character. All morphologic changes of Mi after local ultraviolet irradiation are conserved in descendants and are not photoreactivated. Possible reasons for this phenomenon are discussed. The results obtained make it possible to speak about different mechanisms of action on Mi in the case of local and whole-body UV irradiation of cell. The effect of irradiated Ma on generative nucleus, but not direct damage of this nucleus is the reason for Mi morphologic reconstruction after whole-body action on paramecium

UV emission properties of thulium-doped fluorozirconate glasses

Energy Technology Data Exchange (ETDEWEB)

Piramidowicz, R., E-mail: r.piramidowicz@elka.pw.edu.p [Institute of Microelectronics and Optoelectronics, Koszykowa 75, 00-662 Warsaw (Poland); Telekomunikacja Polska Research and Development Centre, Obrzezna 7, 02-691 Warsaw (Poland); Bok, A.; Klimczak, M.; Malinowski, M. [Institute of Microelectronics and Optoelectronics, Koszykowa 75, 00-662 Warsaw (Poland)

2009-12-15

In this work, we present our latest results on UV emission in bulk ZBLAN glasses doped with thulium ions, broadening knowledge of the short-wavelength optical properties of this system. We examined a set of samples with different activator concentrations (2500, 10,000, 25,000 and 50,000 ppm) in respect of absorption and short-wavelength emission properties. The concentration-dependant spectra of UV emission from the {sup 1}I{sub 6}+{sup 3}P{sub 0} and {sup 1}D{sub 2} levels and fluorescence dynamics profiles have been recorded and carefully examined under direct (one-photon) excitation, enabling discussion of fluorescence quenching mechanisms and determination of appropriate cross-relaxation rates. According to authors' best knowledge, the three-photon red-to-UV up-conversion has been reported for the first time under excitation of a laser diode.

Local Analysis Approach for Short Wavelength Geopotential Variations

Science.gov (United States)

Bender, P. L.

2009-12-01

The value of global spherical harmonic analyses for determining 15 day to 30 day changes in the Earth's gravity field has been demonstrated extensively using data from the GRACE mission and previous missions. However, additional useful information appears to be obtainable from local analyses of the data. A number of such analyses have been carried out by various groups. In the energy approximation, the changes in the height of the satellite altitude geopotential can be determined from the post-fit changes in the satellite separation during individual one-revolution arcs of data from a GRACE-type pair of satellites in a given orbit. For a particular region, it is assumed that short wavelength spatial variations for the arcs crossing that region during a time T of interest would be used to determine corrections to the spherical harmonic results. The main issue in considering higher measurement accuracy in future missions is how much improvement in spatial resolution can be achieved. For this, the shortest wavelengths that can be determined are the most important. And, while the longer wavelength variations are affected by mass distribution changes over much of the globe, the shorter wavelength ones hopefully will be determined mainly by more local changes in the mass distribution. Future missions are expected to have much higher accuracy for measuring changes in the satellite separation than GRACE. However, how large an improvement in the derived results in hydrology will be achieved is still very much a matter of study, particularly because of the effects of uncertainty in the time variations in the atmospheric and oceanic mass distributions. To be specific, it will be assumed that improving the spatial resolution in continental regions away from the coastlines is the objective, and that the satellite altitude is in the range of roughly 290 to 360 km made possible for long missions by drag-free operation. The advantages of putting together the short wavelength

Males do not see only red: UV wavelengths and male territorial aggression in the three-spined stickleback ( Gasterosteus aculeatus)

Science.gov (United States)

Rick, Ingolf P.; Bakker, Theo C. M.

2008-07-01

Animal colour signals serve important functions in intraspecific interactions, including species recognition, mate choice and agonistic behaviour. An increasing interest concerns ultraviolet (UV) wavelengths, for instance studies on the effect of UV in mating decisions. More recently, some studies also established that UV signals affect intrasexual interactions. We studied the role of UV during aggressive encounters between male three-spined sticklebacks ( Gasterosteus aculeatus), a species in which UV has an effect on female and male mate choice and shoaling behaviour. To that aim, we compared the aggressive response of a territorial male to male intruders, either seen in UV-including (UV+) or UV-lacking (UV-) conditions. Our prediction was that, if UV wavelengths are used in male-male competition, a territorial male should show less competitive behaviour towards an intruder representing a lower threat, i.e. the one presented without UV light. Male sticklebacks showed significantly lower levels of aggression towards male opponents lacking an UV component to their coloration than male opponents possessing this colour component. Discrimination was not influenced by a difference in brightness between the UV+ and UV- stimuli. Finally, we present some reflectance-spectrophotometrical data of two skin regions (cheek and abdomen) of the experimental males and analysed relationships between colorimetric variables, body variables and behaviour. Our study emphasises that UV visual cues are of importance in different communicational tasks in the three-spined stickleback.

UV-B radiation and photosynthetic irradiance acclimate eggplant for outdoor exposure

International Nuclear Information System (INIS)

Latimer, J.G.; Mitchell, G.A.

1987-01-01

Treatment of greenhouse-grown eggplant (Solanum melongena L. var. esculentum Nees. 'Burpee's Black Beauty') seedlings with supplemental photosynthetically active radiation from cool-white fluorescent lamps increased growth of plants subsequently transferred outdoors relative to growth of plants that received no supplemental radiation or were shaded to 45% of solar irradiation in the greenhouse before transfer outdoors. Eggplant seedlings transferred outdoors were placed under plastic tarps either to provide relative protection from solar ultraviolet-B (UV-B) radiation (280-315 nm) using Mylar film or to allow exposure to UV-B using cellulose acetate. Protection of seedlings from UV-B radiation resulted in greater leaf expansion than for UV-B-exposed seedlings, but no change in leaf or shoot dry weight occurred after 9 days of treatment. Specific leaf weight increased in response to UV-B exposure outdoors. Exposure of eggplant to UV-B radiation from fluorescent sunlamps in the greenhouse also decreased leaf expansion and leaf and shoot dry weight gain after 5 days of treatment. However, there were no differences in leaf or shoot dry weight relative to control plants after 12 days of UV-B treatment, indicating that UV-B treated plants had acclimated to the treatment and actually had caught up with non-UV-B-irradiated plants in terms of growth

Luminescence spectroscopic observation of singlet oxygen formation in extra virgin olive oil as affected by irradiation light wavelengths, 1,4-diazabicyclo[2.2.2]octane, irradiation time, and oxygen bubbling.

Science.gov (United States)

Jung, Mun Y; Choi, Dong S; Park, Ki H; Lee, Bosoon; Min, David B

2011-01-01

A spectrofluorometer equipped with a highly sensitive near-IR InGaAs detector was used for the direct visualization of singlet oxygen emission at 1268 nm in olive oil during light irradiation with various different wavelengths. The virgin olive oil in methylene chloride (20% w/v, oxygen saturated) was irradiated at the 301, 417, 454, 483, and 668 nm, then the emission at 1268 nm, singlet oxygen dimole decaying was observed. The result showed the highest production of (1)O(2) with light irradiation at 417 nm, and followed by at 668 nm in virgin olive oil, indicating that pheophytin a and chlorophyll a were the most responsible components for the production of singlet oxygen. The UV light irradiations at the wavelength of 200, 250, and 300 nm did not induce any detectable luminescence emission at 1268 nm, but 350 nm produced weak emission at 1269 nm. The quantity of (1)O(2) produced with excitation at 350 nm was about 1/6 of that of irradiation at 417 nm. Addition of an efficient (1)O(2) quencher, 1,4-diazabicyclo[2.2.2]octane, in virgin olive oil in methylene chloride greatly decreased the luminescence emission at 1268 nm, confirming the singlet oxygen production in olive oil. Singlet oxygen production was more efficient in oxygen-purged virgin olive oil than in oxygen non-purged olive oil. This represents first report on the direct observation of singlet oxygen formation in olive oil as well as in real-food system after visible light illumination. Practical Application: The present results show the positive evidence of the singlet oxygen involvement in rapid oxidative deterioration of virgin olive oil under visible light. This paper also shows the effects of different wavelength of light irradiation on the formation of singlet oxygen in olive oil. The present results would provide important information for the understanding of the mechanism involved in rapid oxidative quality deterioration of virgin olive oil under light illumination and for searching the

Specific inhibition of cytotoxic memory cells produced against uv-induced tumors in uv-irradiation mice

International Nuclear Information System (INIS)

Thorn, R.M.

1978-01-01

Cytotoxic responses of uv-irradiated mice against syngeneic uv-induced tumors were measured by using a 51 Cr-release assay to determine if uv treatment induced a specific reduction of cytotoxic activity. The in vivo and in vitro primary responses against syngeneic tumors and allogeneic cells were unaffected, as was the ''memory'' response (in vivo stimulation, in vitro restimulation) against alloantigens. In contrast, the memory response of uv-treated mice against syngeneic, uv-induced tumors was consistently and significantly depressed. The cytotoxicity generated by tumor cell stimulation in vivo or in vitro was tumor-specific and T cell-dependent. Since the primary response against syngeneic uv-induced tumors produces apparently normal amounts of tumor-specific cytotoxic activity, uv-treated mice may not reject transplanted syngeneic tumors because of too few T effector memory cells. These results imply that, at least in this system, tumor rejection depends mostly on the secondary responses against tumor antigens and that at least one carcinogen can, indirectly, specifically regulate immune responses

Damage to UV-sensitive cells by short UV in photographic flashes

International Nuclear Information System (INIS)

Menezes, S.; Monteiro, C.

1996-01-01

Light emitted by electronic photographic flash units is shown to damage bacteria and human skin fibroblasts deficient in repair systems, with survival curves very similar to those produced by 254 nm short UV. The lesions induced by these flashes are as photorepairable by the photolyase enzyme as those induced by 254 nm UV and result in equivalent survival rates. Biological dosimetry performed with microorganisms highly sensitive to UV (Escherichia coli K12 AB2480, deficient in excision and recombinational-dependent repair systems and Bacillus subtilis UVSSP spores, deficient in excision and in a specific spore repair process) revealed that each 1 ms flash of light from the photographic unit used in this work contained the equivalent of 0.25 J m -2 of 254 nm UV, when measured at a distance of 7.0 cm. This dose of UV was found to be lethal to both repair-deficient E. coli bacteria and repair-deficient human skin fibroblasts obtained from xeroderma pigmentosum donors, as well as mutagenic in B/r wild-type and HCR-mutant bacteria. (Author)

Corrosion prevention of iron with novel organic inhibitor of hydroxamic acid and UV irradiation

International Nuclear Information System (INIS)

Deng Huihua; Nanjo, Hiroshi; Qian, Pu; Xia Zhengbin; Ishikawa, Ikuo; Suzuki, Toshishige M.

2008-01-01

Corrosion prevention by self-assembled monolayers (SAM) of monomer and polymer inhibitor on iron covered with air-formed oxide films was investigated by cyclic voltammetry in borate buffer solution. Anti-corrosion efficiency of the SAM-coated Fe electrodes depends on UV irradiation duration on Fe electrodes prior to coating and inhibitor concentration to form SAM. The 1-h UV-irradiated Fe electrodes coated with SAM exhibits the most effective corrosion resistance despite the anti-corrosion efficiency of air-formed films on Fe was linearly increased with UV irradiation. The addition of monomer in polymer solution improves the stability and corrosion resistance of SAM

UV-C irradiation disrupts platelet surface disulfide bonds and activates the platelet integrin alphaIIbbeta3

NARCIS (Netherlands)

Verhaar, Robin; Dekkers, David W. C.; de Cuyper, Iris M.; Ginsberg, Mark H.; de Korte, Dirk; Verhoeven, Arthur J.

2008-01-01

UV-C irradiation has been shown to be effective for pathogen reduction in platelet concentrates, but preliminary work indicated that UV-C irradiation of platelets can induce platelet aggregation. In this study, the mechanism underlying this phenomenon was investigated. Irradiation of platelets with

Effects of gamma radiation on commercial food packaging films--study of changes in UV/VIS spectra

International Nuclear Information System (INIS)

Moura, E.A.B.; Ortiz, A.V.; Wiebeck, H.; Paula, A.B.A.; Silva, A.L.A.; Silva, L.G.A.

2004-01-01

The effects of gamma irradiation doses up to 100 kGy on the optical properties of different commercial packaging films were studied in this paper. The packaging films analyzed were: polyethylene 'LDPE', amide 6-amide 6.6 copolymer 'PA6-PA6.6' and poly(ethylene terephthalate) 'PET'. An investigation on film samples before and after irradiation was performed by UV/VIS spectroscopy. The results showed that, in the absorption spectra of irradiated LDPE and PA6-PA6.6 films, a red-shift in the wavelength of the UV cutoff and a marked reduction in % transmittance (at low wavelengths) occur with increasing radiation dose. With respect to PET samples, no significant changes were observed in either light absorption or transmittance

Effect of uv-irradiation on genetic recombination of Simian virus 40 mutants

International Nuclear Information System (INIS)

Gentil, A.; Margot, A.; Sarasin, A.

1983-01-01

Genetic recombination in monkey kidney cells has been studied using Simian virus 40 (SV40) as a molecular probe. Control or uv-irradiated cells have been co-infected with two thermosensitive mutants of SV40, tsA58 and tsA30. Recombination between the two viral genomes gives rise to a wild type virus phenotype, able to grow at the restrictive temperature of 41 0 C, which was taken as a measure of the recombination activity of the host cells. Results show that recombination takes place at a low frequency when viruses are not uv-irradiated. Irradiation of one or both viruses increases drastically recombination frequency. Pretreatment of the host cells with uv-light or mitomycin C 24 hours before being infected does not increase recombination frequency measured in our experimental conditions. 23 references, 5 tables

Effects of whole body UV-irradiation on oxygen delivery from the erythrocyte

International Nuclear Information System (INIS)

Humpeler, E.; Mairbaeurl, H.; Hoenigsmann, H.

1982-01-01

In 16 healthy caucasian volunteers (mean age: 22.2 years) the influence of whole body UV-irradiation on the oxygen transport properties of erythrocytes was investigated. Four hours after irradiation with UV (using the minimal erythema dose, MED) no variation of haemoglobin concentration, hematocrit, mean corpuscular haemoglobin concentration, pH or standard bicarbonate could be found, whereas inorganic plasma phosphate (Psub(i)), calcium, the intraerythrocytic 2,3-diphosphoglycerate (2,3-DPG), the activity of erythrocytic phosphofructokinase (PFK) and pyruvatekinase (PK) increased significantly. The half saturation tension of oxygen (P 50 -value) tended to increase. The increase of Psub(i) causes - via a stimulation of the glycolytic pathway - an increase in 2,3-DPG concentration and thus results in a shift of the oxygen dissociation curve. It is therefore possible to enhance tissue oxygenation by whole body UV-irradiation. (orig.)

Short-wavelength ablation of polymers in the high-fluence regime

International Nuclear Information System (INIS)

Liberatore, Chiara; Juha, Libor; Vyšín, Ludek; Endo, Akira; Mocek, Tomas; Mann, Klaus; Müller, Matthias; Pina, Ladislav; Rocca, Jorge J

2014-01-01

Short-wavelength ablation of poly(1,4-phenylene ether-ether-sulfone) (PPEES) and poly(methyl methacrylate) (PMMA) was investigated using extreme ultraviolet (XUV) and soft x-ray (SXR) radiation from plasma-based sources. The initial experiment was performed with a 10 Hz desktop capillary-discharge XUV laser lasing at 46.9 nm. The XUV laser beam was focused onto the sample by a spherical mirror coated with a Si/Sc multilayer. The same materials were irradiated with 13.5 nm radiation emitted by plasmas produced by focusing an optical laser beam onto a xenon gas-puff target. A Schwarzschild focusing optics coated with a Mo/Si multilayer was installed at the source to achieve energy densities exceeding 0.1 J cm −2 in the tight focus. The existing experimental system at the Laser Laboratorium Göttingen was upgraded by implementing a 1.2 J driving laser. An increase of the SXR fluence was secured by improving the alignment technique. (paper)

DNA degradation and reduced recombination following UV irradiation during meiosis in yeast (Saccharomyces cerevisiae)

International Nuclear Information System (INIS)

Salts, Y.; Pinon, R.; Simchen, G.

1976-01-01

Irradiation of meiotic yeast cells with moderate doses of ultraviolet irradiation (1,600 erg/mm 2 ) leads to the arrest of premeiotic DNA synthesis, massive (5-40%) DNA degradation, and a 40-50% loss of cell viability. In contrast, such doses of UV irradiation had a minor effect on viability (15-20% loss) of logarithmically growing cells, and no comparable DNA degradation was observed in irradiated synchronized vegetative cells. Meiotic recombination is also affected by UV irradiation. When administered at a stage comparable to meiotic prophase, low doses of irradiation result in a reduction in recombination frequency without significantly affecting cell viability. (orig.) [de

Model animal experiments on UV-c irradiation of blood and isolated cell populations

International Nuclear Information System (INIS)

Repke, H.; Scherf, H.P.; Wiesner, S.

1984-01-01

The cellular and molecular basis of the therapeutically used effect of reinjected ultraviolet (UVC) irradiated blood is unknown. First approaches to that problem were made in this study by aid of model experiments. Neither the spontaneous degranulation nor the antigen-induced histamine release from rat connective tissue mast cells (in vivo) was influenced by the injection (i.v.) of UV-irradiated blood or blood lymphocytes. By comparison of the effect of UV light on blood lymphocytes (number of dead cells, strength of chemoluminescence) after irradiation of the isolated cells and the unfractionated blood, respectively, it was shown that the strong light absorption within the blood sample prevents damage or functional alterations of the blood lymphocytes. The compound 48/80 - induced histamine release from rat peritoneal mast cells can be completely inhibited by UV irradiation (0.6 mJ/cm 2 ) without increasing the spontaneous histamine release. (author)

A thermal after-effect of UV irradiation of muscle glycogen phosphorylase b.

Directory of Open Access Journals (Sweden)

Valeriya V Mikhaylova

Full Text Available Different test systems are used to characterize the anti-aggregation efficiency of molecular chaperone proteins and of low-molecular-weight chemical chaperones. Test systems based on aggregation of UV-irradiated protein are of special interest because they allow studying the protective action of different agents at physiological temperatures. The kinetics of UV-irradiated glycogen phosphorylase b (UV-Phb from rabbit skeletal muscle was studied at 37°C using dynamic light scattering in a wide range of protein concentrations. It has been shown that the order of aggregation with respect to the protein is equal to unity. A conclusion has been made that the rate-limiting stage of the overall process of aggregation is heat-induced structural reorganization of a UV-Phb molecule, which contains concealed damage.

Reactions of the intracellular NADpool in the yeast S. cerevisiae after UV-C- or X-ray irradiation

International Nuclear Information System (INIS)

Winckler, K.; Herfurth, E.

1988-01-01

The reaction of the intracellular NADpool after irradiation of cells either with UV-C light or with X-rays was studied in four different strains of the yeast S. cerevisiae. We found neither in wildtype strains nor in radiation sensitive mutants remarkable changes in the NADpool within 2 h after irradiation. Preculture of cells in medium enriched with nicotinic acid, a precursor of NAD, influenced the intracellular NAD concentration only to a small extent in all strains, but enhanced the radiation resistance against UV-C significantly in one rad6 mutant strain. The uptake of NAD and NAC by all strains before and after irradiation with UV-C and X-ray was tested also. NAD generally is taken up by the cells to a very low extent before and after irradiation without irradiation-dose dependency. NAC is taken up by all strains before and after irradiation. Only the rad6 mutant exhibited an irradiation-dose dependent NAC-uptake after UV-C irradiation. (orig.)

Row orientation effect on UV-B, UV-A and PAR solar irradiation components in vineyards at Tuscany, Italy

Science.gov (United States)

Grifoni, D.; Carreras, G.; Zipoli, G.; Sabatini, F.; Dalla Marta, A.; Orlandini, S.

2008-11-01

Besides playing an essential role in plant photosynthesis, solar radiation is also involved in many other important biological processes. In particular, it has been demonstrated that ultraviolet (UV) solar radiation plays a relevant role in grapevines ( Vitis vinifera) in the production of certain important chemical compounds directly responsible for yield and wine quality. Moreover, the exposure to UV-B radiation (280-320 nm) can affect plant-disease interaction by influencing the behaviour of both pathogen and host. The main objective of this research was to characterise the solar radiative regime of a vineyard, in terms of photosynthetically active radiation (PAR) and UV components. In this analysis, solar spectral UV irradiance components, broadband UV (280-400 nm), spectral UV-B and UV-A (320-400 nm), the biological effective UVBE, as well as the PAR (400-700 nm) component, were all considered. The diurnal patterns of these quantities and the UV-B/PAR and UV-B/UV-A ratios were analysed to investigate the effect of row orientation of the vineyard in combination with solar azimuth and elevation angles. The distribution of PAR and UV irradiance at various heights of the vertical sides of the rows was also studied. The results showed that the highest portion of plants received higher levels of daily radiation, especially the UV-B component. Row orientation of the vines had a pronounced effect on the global PAR received by the two sides of the rows and, to a lesser extent, UV-A and UV-B. When only the diffused component was considered, this geometrical effect was greatly attenuated. UV-B/PAR and UV-A/PAR ratios were also affected, with potential consequences on physiological processes. Because of the high diffusive capacity of the UV-B radiation, the UV-B/PAR ratio was significantly lower on the plant portions exposed to full sunlight than on those in the shade.

Effect of ultraviolet B irradiation on accumulation of catechins in tea ...

African Journals Online (AJOL)

Effect of UV-B irradiation time on accumulation of foliar catechins in two tea cultivars was investigated. Low influence rate and short term irradiation of UV-B stimulated accumulation of major tea catechins, resulting in an increase in level of total catechins. Excessive irradiation of UV-B supressed the accumulation of tea ...

Carcinogenic effect of sequential artificial sunlight and UV-A irradiation in hairless mice. Consequences for solarium 'therapy'

International Nuclear Information System (INIS)

Staberg, B.; Wulf, H.C.; Poulsen, T.; Klemp, P.; Brodthagen, H.

1983-01-01

The carcinogenic effect of artificial UV sunlight followed by UV-A irradiation in human solaria doses has been studied with the use of the hairless mouse as an animal model. Artificial sunlight exposure alone induced only a moderate skin tumor incidence (animals with at least one tumor) of 0.15 after one year, and UV-A irradiation alone induced no tumor formation. However, the combination of artificial sunlight exposure and subsequent UV-A irradiation significantly increased the tumor incidence to 0.72. We conclude that, in humans, tanning with UV-A for cosmetic purposes may not be an innocuous procedure

Effect of laser UV radiation on the eye scleral tissue in patients with open-angle glaucoma

Science.gov (United States)

Razhev, A. M.; Iskakov, I. A.; Churkin, D. S.; Orishich, A. M.; Maslov, N. A.; Tsibul'skaya, E. O.; Lomzov, A. A.; Ermakova, O. V.; Trunov, A. N.; Chernykh, V. V.

2018-05-01

We report the results of an experimental study of the effect of short-pulse laser UV radiation on the eye scleral tissue. As samples, we used isolated flaps of the eye scleral tissue from the patients with open-angle glaucoma of the second and third stages. The impact was implemented using the radiation of an excimer XeCl laser with a wavelength of 308 nm and a laser with a wavelength tunable within from 210 to 355 nm. Depending on the problem to be solved, the energy density on the surface of the irradiated tissue varied from a fraction of mJ cm-2 to 15 J cm-2. For the first time we studied the optical properties of the intraocular fluid in the UV and blue spectral range. The study of the ablation process under the action of radiation with a wavelength of 308 nm showed that the rate of material evaporation can vary within 24%–30% at an energy density above 7 J cm-2, depending on the glaucoma stage and the individual features of a patient. The excitation–emission matrices of laser-induced fluorescence (LIF) of the eye scleral tissue were studied experimentally using a laser with a wavelength tuned in the range 210–355 nm. We found the differences in the LIF spectra caused by the excitation wavelength and the openangle glaucoma stage.

Formation of halogenated C-, N-DBPs from chlor(am)ination and UV irradiation of tyrosine in drinking water

International Nuclear Information System (INIS)

Chu Wenhai; Gao Naiyun; Krasner, Stuart W.; Templeton, Michael R.; Yin Daqiang

2012-01-01

The formation of regulated and emerging halogenated carbonaceous (C-) and nitrogenous disinfection by-products (N-DBPs) from the chlor(am)ination and UV irradiation of tyrosine (Tyr) was investigated. Increased chlorine contact time and/or Cl 2 /Tyr ratio increased the formation of most C-DBPs, with the exception of 4-chlorophenol, dichloroacetonitrile, and dichloroacetamideChloroform and dichloroacetic acid increased with increasing pH, dichloroacetonitrile first increased and then decreased, and other DBPs had maximum yields at pH 7 or 8. The addition of ammonia significantly reduced the formation of most C-DBPs but increased 4-chlorophenol, dichloroacetonitrile, dichloroacetamide, and trichloroacetonitrile yields for short prechlorination contact times before dosing ammonia. When UV irradiation and chlorination were performed simultaneously, the concentrations of the relatively stable C-DBPs increased, and the concentrations of dichloroacetonitrile, dichloroacetamide, and 4-chlorophenol decreased with increasing UV dose. This information was used to develop a mechanistic model for the formation of intermediate DBPs and end products from the interaction of disinfectants with tyrosine. Highlights: ► Increased contact time and/or Cl 2 /Tyr decreased the formation of some N-DBPs. ► Changing the pH of disinfection decreases the formation of some N-DBPs. ► N-DBP yields increased for short prechlorination contact time before dosing ammonia. ► Low pressure UV before chlorination did not impact the formation of DBPs from Tyr. ► A novel integrated formation pathway of halogenated C-, N-DBPs is proposed. - Exploring the integrated formation mechanism of regulated and emerging highly toxic DBPs, which is expected to preferably reduce their occurrence in drinking water.

Effect of Gamma Irradiation and Coagualtion on the Molegular Weight Distribution of Soluble Organic Substances in Paper Mill Effluent

International Nuclear Information System (INIS)

He Shijun; Wang Jianlong; Wan Jianxin; Sun Mengmeng; Ye Longfei

2012-01-01

In order to look into the insights of the influence of gamma irradiation and coagulation on the molecular weight distribution (MWD) of soluble organic substances in real paper mill effluent, various parameters of wastewater samples before and after treated were investigated, including chemical oxygen demand (COD), biochemical oxygen demand (BOD 5 ), dissolved organic carbon (DOC) and absorbance at 254 nm wavelength (UV 254 ) as well. In addition, the effects of irradiation on oxygen uptake and on acute toxicity were also presented. The results showed that irradiation alone cannot promote the biodegradability and oxygen uptake as originally expected. The whole acute toxicity of samples was reduced after gamma irradiation. On the other side, coagulation can not only effectively eliminate the sectors with high molecular weight (MW>3000 Dalton, in short HMW), but also improve the capacity of ionizing irradiation initiated the transformation of medium molecular weight (1000 Dalton< MW<3000 Dalton, in short MMW) into low molecular weight (MW<1000 Dalton, in short LWM), which is readily degraded by the subsequently activated sludge process. (author)

Effect of Gamma Irradiation and Coagualtion on the Molegular Weight Distribution of Soluble Organic Substances in Paper Mill Effluent

Energy Technology Data Exchange (ETDEWEB)

Shijun, He; Jianlong, Wang [Institute of Nuclear and New Energy Technology (INET), Tsinghua University, Beijing 100084 (China); Jianxin, Wan; Mengmeng, Sun [Institute of Nuclear and New Energy Technology (INET), Tsinghua University, Beijing 100084 (China); School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan 430070 (China); Longfei, Ye [Institute of Nuclear and New Energy Technology (INET), Tsinghua University, Beijing 100084 (China); College of Environmental Science and Engineering, Hunan University, Changsha, Hunan 410082 (China)

2012-07-01

In order to look into the insights of the influence of gamma irradiation and coagulation on the molecular weight distribution (MWD) of soluble organic substances in real paper mill effluent, various parameters of wastewater samples before and after treated were investigated, including chemical oxygen demand (COD), biochemical oxygen demand (BOD{sub 5}), dissolved organic carbon (DOC) and absorbance at 254 nm wavelength (UV{sub 254}) as well. In addition, the effects of irradiation on oxygen uptake and on acute toxicity were also presented. The results showed that irradiation alone cannot promote the biodegradability and oxygen uptake as originally expected. The whole acute toxicity of samples was reduced after gamma irradiation. On the other side, coagulation can not only effectively eliminate the sectors with high molecular weight (MW>3000 Dalton, in short HMW), but also improve the capacity of ionizing irradiation initiated the transformation of medium molecular weight (1000 Daltonshort MMW) into low molecular weight (MW<1000 Dalton, in short LWM), which is readily degraded by the subsequently activated sludge process. (author)

The Effect of Lycopene Preexposure on UV-B-Irradiated Human Keratinocytes

Science.gov (United States)

Ascenso, Andreia; Pedrosa, Tiago; Pinho, Sónia; Pinho, Francisco; de Oliveira, José Miguel P. Ferreira; Cabral Marques, Helena; Oliveira, Helena; Simões, Sandra; Santos, Conceição

2016-01-01

Lycopene has been reported as the antioxidant most quickly depleted in skin upon UV irradiation, and thus it might play a protective role. Our goal was to investigate the effects of preexposure to lycopene on UV-B-irradiated skin cells. Cells were exposed for 24 h to 10 M lycopene, and subsequently irradiated and left to recover for another 24 h period. Thereafter, several parameters were analyzed by FCM and RT-PCR: genotoxicity/clastogenicity by assessing the cell cycle distribution; apoptosis by performing the Annexin-V assay and analyzing gene expression of apoptosis biomarkers; and oxidative stress by ROS quantification. Lycopene did not significantly affect the profile of apoptotic, necrotic and viable cells in nonirradiated cells neither showed cytostatic effects. However, irradiated cells previously treated with lycopene showed an increase in both dead and viable subpopulations compared to nonexposed irradiated cells. In irradiated cells, lycopene preexposure resulted in overexpression of BAX gene compared to nonexposed irradiated cells. This was accompanied by a cell cycle delay at S-phase transition and consequent decrease of cells in G0/G1 phase. Thus, lycopene seems to play a corrective role in irradiated cells depending on the level of photodamage. Thus, our findings may have implications for the management of skin cancer. PMID:26664697

Photoreactivation of RNA in UV-irradiated insect eggs (Smittia SP., Chironomidae, Diptera)

International Nuclear Information System (INIS)

Kalthoff, K.; Urban, K.; Jaeckle, H.

1978-01-01

Two biological effects of UV radiation upon Smittia eggs are observed, both of which seem to be associated with the formation of pyrimidine dimers in the RNA (largely ribosomal) of the eggs. While irradiation of the anterior pole region causes the formation of an aberrant segment pattern (double abdomen induction), irradiation of entire eggs leads to an arrest of their development (inactivation). Both UV effects are photoreversible with different action spectra of the photoreactivating light. A dose rate dependence of the photoreactivation can be observed after both UV effects. The saturating dose rate is about 6 W/m 2 (at 440 nm) after UV induction of double abdomens. Upon UV inactivation, the saturating dose rate level for the photoreactivating light is much higher, and a single light flash causes both a considerable biological reactivation and the disappearance of about 7 x 10 9 pyrimidine dimers from the total RNA per egg. The results indicate the presence of heterogeneous light-dependent repair activities acting upon UV induced pyrimidine dimers in the RNA of the eggs. (author)

Survival and mutagenesis in UV-irradiated phage: Multi-hit kinetics of mutation induction and lack of indirect induction by infection with UV-irradiated phage of error-prone repair

International Nuclear Information System (INIS)

Krauss, G.; Mennigmann, H.D.; Kaplan, R.W.

1980-01-01

The paper is concerned with the question of whether Weigle-reactivation (WR) and Weigle-mutagenesis (WM) can be indirectly induced by infection with UV-irradiated phage. Experiments neither with phage lambda of Escherichia coli nor with phage kappa of Serratia marcescens show such induction. In this respect phage DNA differs from F'-DNA or Hfr-DNA; possible explanations are discussed. In both systems clear plaque mutations can also be induced by UV without irradiation of the host cells; they appear, in unirradiated and irradiated host cells, with an increase in frequency which is greater than proportional to the UV dose. It is concluded that mutation induction of phage in the unirradiated host cells is due to a low level constitutive mutagenic repair; this could either be due to 'spontaneous' induction of the mutagenic SOS function or it could be a mechanism different from this one. Host irradiation would give rise to additional activity by the induced SOS function leading to WR and WM. It is further concluded that deviation of the induction kinetics from a linear dose-dependence is not due to the necessary induction of SOS functions. (author)

Absorption of uv-radiation by Chibro trademark -Uvelin eye drops

International Nuclear Information System (INIS)

Schreder, J.G.; Blumthaler, M.; Daxer, A.; Ettl, A.

1998-01-01

The preparation Chibro trademark -Uvelin is recommended against both solar and artificial uv-radiation. At wavelengths greater than 290 nm and at an effective layer thickness of 10 μm measurements with a high resolution doublemonochromator showed a transmission larger than 90%. The solar spectrum is characterised by almost no irradiance on the earth's surface for wavelengths smaller than 290 nm due to absorption in the atmospheric ozon layer. Therefore, no significant protective effect of the eye-drops against keratitis and cataract under solar exposure can be expected. A significantly better sagging of the radiation of artificial UV-sources with a high amount of UV-C is reached. The recommended application as chemical protective goggles in this spectral range is not permissible. (orig.) [de

Repair and mutagenesis of herpes simplex virus in UV-irradiated monkey cells

International Nuclear Information System (INIS)

Lytle, C.D.; Goddard, J.G.; Lin, C.H.

1980-01-01

Mutagenic repair in mammalian cells was investigated by determining the mutagenesis of UV-irradiated or unirradiated herpes simplex virus in UV-irradiated CV-1 monkey kidney cells. These results were compared with the results for UV-enhanced virus reactivation (UVER) in the same experimental situation. High and low multiplicities of infection were used to determine the effects of multiplicity reactivation (MR). UVER and MR were readily demonstrable and were approximately equal in amount in an infectious center assay. For this study, a forward-mutation assay was developed to detect virus mutants resistant to iododeoxycytidine (ICdR), probably an indication of the mutant virus being defective at its thymidine kinase locus. ICdR-resistant mutants did not have a growth advantage over wild-type virus in irradiated or unirradiated cells. Thus, higher fractions of mutant virus indicated greater mutagenesis during virus repair and/or replication. The data showed that: (1) unirradiated virus was mutated in unirradiated cells, providing a background level of mutagenesis; (2) unirradiated virus was mutated about 40% more in irradiated cells, indicating that virus replication (DNA synthesis) became more mutagenic as a result of cell irradiation; (3) irradiated virus was mutated much more (about 6-fold) than unirradiated virus, even in unirradiated cells; (4) cell irradiation did not change the mutagenesis of irradiated virus except at high multiplicity of infection. High multiplicity of infection did not demonstrate UVER or MR alone to be either error-free or error-prone. When the two processes were present simultaneously, they were mutagenic. (orig.)

Surface photo-discoloration and degradation of dyed wood veneer exposed to different wavelengths of artificial light

Energy Technology Data Exchange (ETDEWEB)

Liu, Yi [MOE Key Laboratory of Wooden Material Science and Application, Beijing Forestry University, Beijing 100083 (China); Beijing Key Laboratory of Wood Science and Engineering, Beijing Forestry University, Beijing 100083 (China); MOE Engineering Research Center of Forestry Biomass Materials and Bioenergy, Beijing Forestry University, Beijing 100083 (China); Forest Products Development Center, School of Forestry and Wildlife Sciences, Auburn University, Auburn, AL 36830 (United States); Shao, Lingmin [MOE Key Laboratory of Wooden Material Science and Application, Beijing Forestry University, Beijing 100083 (China); Gao, Jianmin, E-mail: jmgao@bjfu.edu.cn [MOE Key Laboratory of Wooden Material Science and Application, Beijing Forestry University, Beijing 100083 (China); Beijing Key Laboratory of Wood Science and Engineering, Beijing Forestry University, Beijing 100083 (China); MOE Engineering Research Center of Forestry Biomass Materials and Bioenergy, Beijing Forestry University, Beijing 100083 (China); Guo, Hongwu, E-mail: hwg5052@163.com [MOE Key Laboratory of Wooden Material Science and Application, Beijing Forestry University, Beijing 100083 (China); Beijing Key Laboratory of Wood Science and Engineering, Beijing Forestry University, Beijing 100083 (China); MOE Engineering Research Center of Forestry Biomass Materials and Bioenergy, Beijing Forestry University, Beijing 100083 (China); Chen, Yao [MOE Key Laboratory of Wooden Material Science and Application, Beijing Forestry University, Beijing 100083 (China); Beijing Key Laboratory of Wood Science and Engineering, Beijing Forestry University, Beijing 100083 (China); MOE Engineering Research Center of Forestry Biomass Materials and Bioenergy, Beijing Forestry University, Beijing 100083 (China); Cheng, Qingzheng; Via, Brian K. [Forest Products Development Center, School of Forestry and Wildlife Sciences, Auburn University, Auburn, AL 36830 (United States)

2015-03-15

Highlights: • Investigate the selective absorption of different wavelengths of UV–vis light by dyed wood chromophores. • Identify connection between light wavelengths and surface color changes and chemical structure degradation. • Study hypochromic effect based on surface reflectance and K/S absorption changes during UV–vis irradiation. - Abstract: The surface of dyed wood is prone to discoloration when exposed to light irradiation which significantly decreases its decorative effect and shortens its service life. The influence of light wavelength exposure to the surface of dyed wood was investigated to study the effect on discoloration and degradation. Acid Blue V and Acid Red GR dyed wood veneers were subjected to light exposure with different wavelengths from the UV to visible region (254–420 nm). Results showed that the surface discoloration of dyed wood was linearly related to lignin concentration and dyes degradation and the consequent transformation of chromophoric groups such as aromatic (C=C) and carbonyl (C=O) through methoxy reaction. The dyes, lignin and some active constituents were degraded severely, even at short exposures. Acid Blue V dyed wood exhibited greater discoloration than the Acid Red GR treatment. The reflectance and K/S absorption curve showed a hypochromic effect on the dyed wood surface. The dyes and wood chemical structure played a complex and combined role on the selective absorption of different wavelengths of light. The color change rate was apparent with 254 nm exposure in the initial stages, but a greater discoloration rate occurred on the samples irradiated at 313 and 340 nm than at 254 and 420 nm with the time prolonged. The degradation rate and degree of discoloration correlated well with the light energy and wavelength.

The optimal UV exposure time for vitamin D3 synthesis and erythema estimated by UV observations in Korea

Science.gov (United States)

Lee, Y. G.; Koo, J. H.

2016-12-01

Solar UV radiation in a wavelength range between 280 to 400 nm has both positive and negative influences on human body. Surface UV radiation is the main natural source of vitamin D, providing the promotion of bone and musculoskeletal health and reducing the risk of a number of cancers and other medical conditions. However, overexposure to surface UV radiation is significantly related with the majority of skin cancer, in addition other negative health effects such as sunburn, skin aging, and some forms of eye cataracts. Therefore, it is important to estimate the optimal UV exposure time, representing a balance between reducing negative health effects and maximizing sufficient vitamin D production. Previous studies calculated erythemal UV and vitamin-D UV from the measured and modelled spectral irradiances, respectively, by weighting CIE Erythema and Vitamin D3 generation functions (Kazantzidis et al., 2009; Fioletov et al., 2010). In particular, McKenzie et al. (2009) suggested the algorithm to estimate vitamin-D production UV from erythemal UV (or UV index) and determined the optimum conditions of UV exposure based on skin type Ⅱ according to the Fitzpatrick (1988). Recently, there are various demands for risks and benefits of surface UV radiation on public health over Korea, thus it is necessary to estimate optimal UV exposure time suitable to skin type of East Asians. This study examined the relationship between erythemally weighted UV (UVEry) and vitamin D weighted UV (UVVitD) from spectral UV measurements during 2006-2010. The temporal variations of the ratio (UVVitD/UVEry) were also analyzed and the ratio as a function of UV index was applied to the broadband UV measured by UV-Biometer at 6 sites in Korea Thus, the optimal UV exposure time for vitamin D3 synthesis and erythema was estimated for diurnal, seasonal, and annual scales over Korea. In summer with high surface UV radiation, short exposure time leaded to sufficient vitamin D and erythema and vice

Novel phenomena in clusters irradiated by short-wavelength free-electron lasers

International Nuclear Information System (INIS)

Fukuzawa, Hironobu; Ueda, Kiyoshi

2017-01-01

By electron spectroscopy, we investigated various phenomena that are caused by the irradiation of extreme ultraviolet (EUV) and X-ray free-electron laser (FEL) pulses on rare-gas clusters. The results for the Ne clusters, which were irradiated by EUVFEL pulses at a photon energy of 20.3 eV below the ionization threshold, illustrate that novel interatomic processes yield low-energy electrons. The results for the Xe clusters, irradiated by EUVFEL pulses at a photon energy of 24.3 eV above the threshold, illustrate that nanoplasma is formed as a result of trapping the photoelectrons and consequently emits low-energy thermal electrons. The results for the Ar clusters irradiated by 5 keV XFEL pulses illustrate that nanoplasma is formed by trapping low-energy Auger electrons and secondary electrons in the tens of fs range, and continuous thermal emission from the plasma occurs in the ps range. (author)

Estimates of SASE power in the short wavelength region

International Nuclear Information System (INIS)

Kim, Kwang-Je.

1992-03-01

Given a sufficiently bright electron beam, the self-amplified-spontaneous emission (SASE) can provide gigawatts of short wavelength coherent radiation. The advantages of SASE approach are that is requires neither optical cavity nor an imput seed laser. In this note, we estimate the peak power performance of SASE for wavelengths shorter than 1000 Angstrom. At each wavelength, we calculate the saturated power from a uniform parameter undulator and the enhanced power from a tapered undulator. The method described here is an adaptation of that discussed by L.H. Yu, who discussed the harmonic generation scheme with seeded laser, to the case of SASE

Effect of UV irradiation on Cu2ZnSnS4 thin films prepared by the sol–gel sulfurization method

International Nuclear Information System (INIS)

Miyazawa, Hayato; Tanaka, Kunihiko; Uchiki, Hisao

2015-01-01

Cu 2 ZnSnS 4 (CZTS) thin films were fabricated on Mo-coated soda lime glass substrates by the sol–gel sulfurization method, which is a non-vacuum process. UV irradiation was introduced to the drying process, resulting in a significant increase in the grain size and density as well as a remarkable improvement in the crystallinity of the CZTS films. In addition, sulfurization of the Mo substrate was suppressed due to the increased density. We confirmed that the carbon/metal ratio in the precursor increased as a result of the UV irradiation. - Graphical abstract: Surface and cross sectional SEM images of the (a) CZTS prepared without UV irradiation and (b) CZTS prepared with UV irradiation. - Highlights: • CZTS thin film was prepared by sol–gel sulfurization method. • UV irradiation was introduced during the drying process. • Density and crystallinity of the CZTS films were improved by the UV irradiation. • Sulfurization of Mo substrates was suppressed by the UV irradiation.

Effect of arsenite on the DNA repair of UV-irradiated Chinese hamster ovary cells

International Nuclear Information System (INIS)

Lee-Chen, S.F.; Yu, C.T.; Jan, K.Y.

1992-01-01

Arsenite, an ubiquitous human carcinogen, has been shown to enhance the cytotoxicity, mutagenicity and clastogenicity of UV light in mammalian cells. Arsenite may exert its co-genotoxic effects by inhibiting DNA repair. Results from alkaline sucrose gradient sedimentation show that arsenite did not accumulate UV-induced DNA strand breaks in Chinese hamster ovary (CHO) K1 cells as aphidicolin plus hydroxyurea (HU) did. These data indicate that arsenite did not inhibit the activity of DNA polymerase α in UV repair. Treatment with arsenite before UV irradiation slightly reduced the DNA strand breaks accumulated by cytosine β-D-arabinofuranoside (AraC) plus HU. This effect implies that arsenite only slightly inhibited the incision of UV-induced DNA adducts. The low molecular weight DNA accumulated by post-UV incubation with AraC plus HU shifted to high molecular weight upon the incubation of cells in drug-free medium, but this shifting was prohibited by the presence of arsenite. This suggests that arsenite inhibited the rejoining of DNA strand breaks. When a pulse-chase labelling procedure was applied on UV-irradiated cells, the chain elongation of nascent DNA was strongly inhibited by post-incubation with arsenite. These data show that arsenite inhibited post-replication repair in UV-irradiated cells. Therefore, the steps inhibited by arsenite in UV-induced cells. Therefore, the steps inhibited by arsenite in UV-induced DNA repair in CHO K1 cells are different from human fibroblasts. (author)

Effect of arsenite on the DNA repair of UV-irradiated Chinese hamster ovary cells

Energy Technology Data Exchange (ETDEWEB)

Lee-Chen, S.F.; Yu, C.T.; Jan, K.Y. (Academia Sinica, Taipei, (Taiwan). Institute of Zoology)

1992-01-01

Arsenite, an ubiquitous human carcinogen, has been shown to enhance the cytotoxicity, mutagenicity and clastogenicity of UV light in mammalian cells. Arsenite may exert its co-genotoxic effects by inhibiting DNA repair. Results from alkaline sucrose gradient sedimentation show that arsenite did not accumulate UV-induced DNA strand breaks in Chinese hamster ovary (CHO) K1 cells as aphidicolin plus hydroxyurea (HU) did. These data indicate that arsenite did not inhibit the activity of DNA polymerase [alpha] in UV repair. Treatment with arsenite before UV irradiation slightly reduced the DNA strand breaks accumulated by cytosine [beta]-D-arabinofuranoside (AraC) plus HU. This effect implies that arsenite only slightly inhibited the incision of UV-induced DNA adducts. The low molecular weight DNA accumulated by post-UV incubation with AraC plus HU shifted to high molecular weight upon the incubation of cells in drug-free medium, but this shifting was prohibited by the presence of arsenite. This suggests that arsenite inhibited the rejoining of DNA strand breaks. When a pulse-chase labelling procedure was applied on UV-irradiated cells, the chain elongation of nascent DNA was strongly inhibited by post-incubation with arsenite. These data show that arsenite inhibited post-replication repair in UV-irradiated cells. Therefore, the steps inhibited by arsenite in UV-induced cells. Therefore, the steps inhibited by arsenite in UV-induced DNA repair in CHO K1 cells are different from human fibroblasts. (author).

OMEGA: a short-wavelength laser for fusion experiments

International Nuclear Information System (INIS)

Soures, J.M.; Hutchison, R.J.; Jacobs, S.D.; Lund, L.D.; McCrory, R.L.; Richardson, M.C.

1983-01-01

The OMEGA, Nd:glass laser facility was constructed for the purpose of investigating the feasibility of direct-drive laser fusion. With 24 beams producing a total energy of 4 kJ or a peak power of 12 TW, OMEGA is capable of nearly uniform illumination of spherical targets. Six of the OMEGA beams have recently been converted to short-wavelength operation (351 nm). In this paper, we discuss details of the system design and performance, with particular emphasis on the frequency-conversion system and multi-wavelength diagnostic system

Research with high-power short-wavelength lasers

International Nuclear Information System (INIS)

Holzrichter, J.F.; Campbell, E.M.; Lindl, J.D.; Storm, E.

1985-01-01

Three important high-temperature, high-density experiments were conducted recently using the 10-TW, short-wavelength Novette laser system at the Lawrence Livermore National Laboratory. These experiments demonstrated successful solutions to problems that arose during previous experiments with long wavelength lasers (lambda greater than or equal to 1μm) in which inertial confinement fusion (ICF), x-ray laser, and other high-temperature physics concepts were being tested. The demonstrations were: (1) large-scale plasmas (typical dimensions of up to 1000 laser wavelengths) were produced in which potentially deleterious laser-plasma instabilities were collisionally damped. (2) Deuterium-tritium fuel was imploded to a density of 20 g/cm 3 and a pressure of 10 10 atm. (3) A 700-fold amplification of soft x rays by stimulated emission at 206 and 209 A (62 eV) from Se +24 ions was observed in a laser-generated plasma. Isoelectronic scaling to 155 A (87 eV) in Y +29 was also demonstrated

Protective effect of poly ({alpha}-L-glutamate) against UV and {gamma}-irradiation

Energy Technology Data Exchange (ETDEWEB)

Furuta, Masakazu E-mail: mfuruta@riast.osakafu-u.ac.jp; Huy, Nguyen Quang; Tsuchiya, Akihito; Nakatsuka, Hiroshige; Hayashi, Toshio

2004-10-01

We occasionally found that poly ({alpha}-L-glutamate) showed a superior protective effect on enzymes against UV and {sup 60}Co-{gamma} irradiation. We selected papain and {alpha}-amylase as a model enzyme and irradiated the aqueous solution (10 mg/ml) of each enzyme with UV and {sup 60}Co-{gamma} rays in the presence of poly ({alpha}-L-glutamate) ({alpha}-PGA), poly (glucosyl oxyethyl methacrylate (GEMA)), and glucose (1.25% w/v each). The mixture of the three compounds has a significant protective effect on the activity of papain solution showing 40% of remaining activity twice as much as the control containing no additive at the dose of 15 kGy. Among them, {alpha}-PGA showed the highest protecting effect on the both papain and {alpha}-amylase even after 10-kGy irradiation at which 50% of the activity was retained. {alpha}-PGA also showed significant protective activity on {alpha}-amylase against UV both in solution and under dried state.

Protective effect of poly (α-L-glutamate) against UV and γ-irradiation

International Nuclear Information System (INIS)

Furuta, Masakazu; Huy, Nguyen Quang; Tsuchiya, Akihito; Nakatsuka, Hiroshige; Hayashi, Toshio

2004-01-01

We occasionally found that poly (α-L-glutamate) showed a superior protective effect on enzymes against UV and 60 Co-γ irradiation. We selected papain and α-amylase as a model enzyme and irradiated the aqueous solution (10 mg/ml) of each enzyme with UV and 60 Co-γ rays in the presence of poly (α-L-glutamate) (α-PGA), poly (glucosyl oxyethyl methacrylate (GEMA)), and glucose (1.25% w/v each). The mixture of the three compounds has a significant protective effect on the activity of papain solution showing 40% of remaining activity twice as much as the control containing no additive at the dose of 15 kGy. Among them, α-PGA showed the highest protecting effect on the both papain and α-amylase even after 10-kGy irradiation at which 50% of the activity was retained. α-PGA also showed significant protective activity on α-amylase against UV both in solution and under dried state

Depression of pyrimidine dimer excision from the aspects of uv reversibility of irradiated cells

Energy Technology Data Exchange (ETDEWEB)

Slamenova, D; Slezarikova, V; Masek, F [Slovenska Akademia Vied, Bratislava (Czechoslovakia)

1977-04-01

Depression of pyrimidine dimer excision induced in uv-irradiated E.coli B/r T/sup -/trp/sup -/Hcr/sup +/ cells by preirradiation cultivation in conditions of starving for the essential amino acid and thymine does not increase uv-reversibility of irradiated cells and does not influence the time of expression of trp/sup +/ reversions. The expression of mutations becomes completed in control and prestarved cells prior to restoration of postradiation division. Genetic deficiency leads up to their high sensitivity to the mutagenic activity of uv irradiation. Expression of trp/sup +/ revertants in Hcr/sup -/ type cells does not become completed until after commencement of the postradiation division of irradiated cells. Prestarved E.coli B/r T/sup -/trp/sup -/Hcr/sup +/ cells exhibited depression of excision even with postradiation cultivation in the absence of an essential amino acid, which is associated with greater stability of newly synthesized DNA and overall decrease of the death rate of cells. In postradiation starvation for the essential amino acid E.coli B/r T/sup -/trp/sup -/Hcr/sup -/ cells irradiated with low uv light doses behaved similarly. Control E.coli B/r T/sup -/trp/sup -/Hcr/sup +/ cells, cultivated after irradiation without amino acid, excised pyrimidine dimers; they are characterised by high degradation of newly synthesized DNA and increased death rate of cells.

Prevention of MHC-alloimmunization by UV-B irradiation in a murine model: effects of UV dose and number of transfused cells

International Nuclear Information System (INIS)

Grijzenhout, M.A.; Claas, F.H.J.

1994-01-01

The optimal dose of UV-B radiation for prevention of in vivo alloimmunization (AI) against major histocompatibility complex (MHC) antigens was investigated in a murine transfusion model. Two groups with five C57BL/6 mice (H-2 b ) each were transfused at weekly intervals with 1 x 10 5 or 1 x 10 6 DBA/2 (H-2 d ) leucocytes. Both suspensions induced anti-H-2 d antibodies in all mice after the second transfusion. The minimal UV-B dose required for abolition of alloreactivity in the mixed leucocyte reaction (MLR) was 0.6 J/cm 2 . This dose completely prevented the onset of MHC-AI in all five mice transfused with six suspensions containing 1 x 10 5 leucocytes. In contrast, suspensions with 1 x 10 6 leucocytes and exposed to 0.6 J/cm 2 induced immunization in 4/5 mice. Further increase of the dose to 1.8 or 5.4 J/cm 2 did not prevent the onset of MHC-AI. We conclude that the number of leucocytes per transfusion determines the efficacy of UV irradiation for the prevention of MHC-AI. For UV irradiation of human platelet concentrates (PCs) we propose to reduce the number of leucocytes by centrifugation prior to UV exposure. UV-B irradiation of PCs with high numbers of leucocytes may not be effective for prevention of alloimmunization. (Author)

Mutation induction by and mutational interaction between monochromatic wavelength radiations in the near-ultraviolet and visible ranges

International Nuclear Information System (INIS)

Tyrrell, R.M.

1980-01-01

The induction of mutations (reversion to tryptophan independence) by various UV (254, 313, 334 and 365 nm) and visible (405 and 434 nm) wavelengths was measured in exponential phase populations of Escherichia coli B/r thy trp and B/r thy trp uvr A by assay of irradiated populations on semi-enriched media. No mutations were induced in the repair proficient strain at wavelengths longer than 313 nm. Mutations were induced to the excisionless strain at wavelengths as long as 405 nm but less than expected from the known amount of DNA damage induced. Irradiation at the long wavelenths (434, 405, 365 and 334 nm) suppressed the appearance of 254- or 313 nm-induced mutations in the repair competent strain but not in the excision deficient strain. The relative dose-requirement for mutation suppression was related to the relative efficiency of these wavelengths in inducing growth delay. These results suggest that the growth delay induced by near-UV and visible wavelenghts allows more time for the 'error-free' excision repair process to act on the potentially mutagenic lesions induced by 254- and 313-nm radiations, thereby reducing the mutation frequency observed in the repair-proficient strain. The level of near-UV mutation induced in the excision deficient strain is lower than expected from the DNA damage known to be induced. It is possible that near-UV radiation induces a class of lethal lesions that are not susceptible to error-prone repair. (author)

Direct synthesis of graphitic mesoporous carbon from green phenolic resins exposed to subsequent UV and IR laser irradiations

Science.gov (United States)

Sopronyi, Mihai; Sima, Felix; Vaulot, Cyril; Delmotte, Luc; Bahouka, Armel; Matei Ghimbeu, Camelia

2016-01-01

The design of mesoporous carbon materials with controlled textural and structural features by rapid, cost-effective and eco-friendly means is highly demanded for many fields of applications. We report herein on the fast and tailored synthesis of mesoporous carbon by UV and IR laser assisted irradiations of a solution consisting of green phenolic resins and surfactant agent. By tailoring the UV laser parameters such as energy, pulse repetition rate or exposure time carbon materials with different pore size, architecture and wall thickness were obtained. By increasing irradiation dose, the mesopore size diminishes in the favor of wall thickness while the morphology shifts from worm-like to an ordered hexagonal one. This was related to the intensification of phenolic resin cross-linking which induces the reduction of H-bonding with the template as highlighted by 13C and 1H NMR. In addition, mesoporous carbon with graphitic structure was obtained by IR laser irradiation at room temperature and in very short time periods compared to the classical long thermal treatment at very high temperatures. Therefore, the carbon texture and structure can be tuned only by playing with laser parameters, without extra chemicals, as usually required. PMID:28000781

Photoreactivation of developmental abnormality in sea urchin embryos induced by UV-irradiated sperm

International Nuclear Information System (INIS)

Ejima, Yosuke; Shiroya, Tuguo.

1980-01-01

The effects of UV-irradiation of sperm on the embryonic development of sea urchins (H. pulcherrimus, Anthocidaris crassispina, Pseudocentrotus depressus, and C. japonicus) were studied. Eggs inseminated with UV-irradiated sperm developed almost normally into blastulae without arrest of cleavage or hatching, even though they showed some division delay. Morphogenesis was disturbed in and after the gastrula stage, and the formation of normal pluteus larvae was inhibited depending on the UV dose (5 - 30 J/m 2 ) given to the sperm. Morphological abnormalities observed were as follows: inhibition of gastrulation; abnormal delamination and random arrangement of primary mesenchymal cells onto the ectodermal wall; abnormal localization or an excess number of spicules; malformed skeletons. These developmental abnormalities were photoreactivated with high efficiency. Inhibition of pluteus formation to less than 5% by the UV-irradiation with 20 J/m 2 completely recovered under fluorescent light illumination with 10 klux. By treating the eggs with brief illumination at various times after insemination, a stage-dependent change of the photoreactivation (PR) efficiency was found. PR treatment after the insemination up to the onset of the first DNA synthesizing phase was highly effective for the recovery, while the PR efficiency began to decrease during the S phase, becoming zero on and after the end of the phase. In eggs fertilized with UV-irradiated sperm, mitoses were abnormal and shromosomal bridges were formed at the anaphase of the first mitosis. Their frequency increased depending on the UV dose. The mitotic abnormality was also photoreactivated with visible light treatment after fertilization. The change in PR efficiency of the illumination was very similar to that of morphological abnormality. (Author)

Effect of UV irradiation on aflatoxin reduction: a cytotoxicity evaluation study using human hepatoma cell line.

Science.gov (United States)

Patras, Ankit; Julakanti, Sharath; Yannam, Sudheer; Bansode, Rishipal R; Burns, Mallory; Vergne, Matthew J

2017-11-01

In this proof-of-concept study, the efficacy of a medium-pressure UV (MPUV) lamp source to reduce the concentrations of aflatoxin B 1 , aflatoxin B 2 , and aflatoxin G 1 (AFB 1, AFB 2 , and AFG 1 ) in pure water is investigated. Irradiation experiments were conducted using a collimated beam system operating between 200 to 360 nm. The optical absorbance of the solution and the irradiance of the lamp are considered in calculating the average fluence rate. Based on these factors, the UV dose was quantified as a product of average fluence rate and treatment time. Known concentrations of aflatoxins were spiked in water and irradiated at UV doses ranging from 0, 1.22, 2.44, 3.66, and 4.88 J cm -2 . The concentration of aflatoxins was determined by HPLC with fluorescence detection. LC-MS/MS product ion scans were used to identify and semi-quantify degraded products of AFB 1 , AFB 2 , and AFG 1 . It was observed that UV irradiation significantly reduced aflatoxins in pure water (p UV light may have caused photolysis of AFB 1 , AFB 2 , and AFG 1 molecules. In cell culture studies, our results demonstrated that the increase of UV dosage decreased the aflatoxin-induced cytotoxicity in HepG 2 cells. Therefore, our research finding suggests that UV irradiation can be used as an effective technique for the reduction of aflatoxins.

Vitamin C affects the antioxidative/oxidative status in rats irradiated with ultraviolet (UV) and infrared (IR) light

DEFF Research Database (Denmark)

Niemiec, T.; Sawosz, E.; Chwalibog, André

2006-01-01

Four grups of twenty growing Wistar rats were irradiated with either UV, IR, UV+IR light or were not irradiated (control). Ten rats from each group received a diet supplemented with 0.6% of L-ascorbic acid. The effects of the mega-dose of vitamin C were evaluated by changes in the antioxidative....../oxidative status. UV and IR radiation promoted oxidative DNA degradation in rat livers and supplementation with ascorbic acid strengthened the prooxidative effects on DNA oxidation in rats irradiated with UV or IR light. Vitamin C also increased the tiobarbituric acid reactive substances (TBARS) concentration...

Modeling of UV laser-induced patterning of ultrathin Co films on bulk SiO2: verification of short- and long-range ordering mechanisms

Science.gov (United States)

Trice, Justin; Favazza, Christopher; Kalyanaraman, Ramki; Sureshkumar, R.

2006-03-01

Irradiating ultrathin Co films (1 to 10 nm) by a short-pulsed UV laser leads to pattern formation with both short- and long-range order (SRO, LRO). Single beam irradiation produces SRO, while two-beam interference irradiation produces a quasi-2D arrangement of nanoparticles with LRO and SRO. The pattern formation primarily occurs in the molten phase. An estimate of the thermal behavior of the film/substrate composite following a laser pulse is presented. The thermal behavior includes the lifetime of the liquid phase and the thermal gradient during interference heating. Based on this evidence, the SRO is attributed to spinodal dewetting of the film while surface tension gradients induced by the laser interference pattern appear to influence LRO [1]. [1] C.Favazza, J.Trice, H.Krishna, R.Sureshkumar, and R.Kalyanaraman, unpublished.

Replication of UV-irradiated DNA in human cell extracts: Evidence for mutagenic bypass of pyrimidine dimers

International Nuclear Information System (INIS)

Thomas, D.C.; Kunkel, T.A.

1993-01-01

The authors have examined the efficiency and fidelity of simian virus 40-origin-dependent replication of UV-irradiated double-stranded DNA in extracts of human cells. Using as a mutational target the α-complementation domain of the Escherichia coli lacZ gene in bacteriophage M13mp2DNA, replication of undamaged DNA in HeLa cell extracts was highly accurate, whereas replication of DNA irradiated with UV light (280-320 nm) was both less efficient and less accurate. Replication was inhibited by irradiation in a dose-dependent manner. Nonetheless, covalently closed, monomer-length circular products were generated that were resistant to digestion by Dpn I, showing that they resulted from semiconservative replication. These products were incised by T4 endonuclease V, whereas the undamaged replication products were not, suggesting that pyrimidine dimers were bypassed during replication. When replicated, UV-irradiated DNA was used to transfect an E. coli α-complementation host strain to score mutant M13mp2 plaques, the mutant plaque frequency was substantially higher than that obtained with either unirradiated, replicated DNA, or unreplicated, UV-irradiated DNA. Both the increased mutagenicity and the inhibition of replication associated with UV irradiation were reversed by treatment of the irradiated DNA with photolyase before replication. Sequence analysis of mutants resulting from replication of UV-irradiated DNA demonstrated that most mutants contained C → T transition errors at dipyrimidine sites. A few mutants contained 1-nt frameshift errors or tandem double CC → TT substitutions. The data are consistent with the interpretation that pyrimidine dimers are bypassed during replication by the multiprotein replication apparatus in human cell extracts and that this bypass is mutagenic primarily via misincorporation of dAMP opposite a cytosine (or uracil) in the dimer. 56 refs., 2 figs., 3 tabs

Ozone and ultraviolet-B irradiances: experimental determination of the radiation amplification factor

International Nuclear Information System (INIS)

Blumthaler, M.; Salzgeber, M.; Ambach, W.

1995-01-01

During the period 1981-1993, measurements of solar UV irradiances were made at the High-Alpine Research Station Jungfraujoch (Switzerland, 3576 m a.s.l.) to determine the radiation amplification factor (RAF) for the Robertson-Berger sunburn meter and for the narrow-band wavelength ranges of the Eppley filter spectrometer. The Robertson-Berger sunburn meter model 500 showed a RAF of 1.07 ± 0.15 at solar elevations between 20 o and 60 o . The RAF for human erythema is 1.1 in comparison. Therefore the Robertson-Berger sunburn meter is suitable to measure the influence of total atmospheric ozone variations on the effective erythemal irradiance. In the narrow-band wavelength ranges of the Eppley filter spectrometer the RAF increases greatly at shorter wavelengths with RAF of 1.06, 1.40 and 2.35 for the optical centers 315.1 nm, 311.1 nm and 305.2 nm, evaluated at 30 o solar elevation. In order to minimize perturbations by aerosol optical depth and albedo in the evaluation of the RAF the ratios of UV irradiances to total irradiances were evaluated. (Author)

UV irradiation alters deoxynucleoside triphosphate pools in Escherichia coli

International Nuclear Information System (INIS)

Das, S.K.; Loeb, L.A.

1984-01-01

UV irradiation of exponentially growing Escherichia coli increased intracellular concentration of dATP and dTTP without significantly changing the concentrations of dGTP and dCTP. These selective increases in dATP and dTTP pools are seen in wild-type E. coli K12 and AB1157, as well as in recA and umuC strains, and are proportional to UV dose. The possible significance of these findings with respect to induction of the SOS response and nontargeted mutagenesis are discussed. (orig.)

Photoreactivation rescue and dark repair demonstrated in UV-irradiated embryos of the self-fertilizing fish Rivulus ocellatus marmoratus (Teleostei; Aplocheilidae)

International Nuclear Information System (INIS)

Park, E.-H.; Yi, A.-K.

1989-01-01

The effects of photoreactivation (PR) rescue and dark repair on the survival of UV-irradiated embryos of the hermaphroditic fish (Rivulus ocellatus marmoratus) are reported. When UV-irradiated embryos were illuminated by photoreactivating light (PRL) from fluorescent lamps, survival at the hatching stage was markedly increased. The maximum recovery to UV damage was shown by embryos that were exposed to PRL for at least 6 h after UV irradiation. The effect of PRL decreased 30 min after UV irradiation and not PR rescue ws detected beyond 96 h. Treatment with 2 mM caffeine for 48 h after UV irradiation increased the sensitivity of the embryos in the dark. The above results demonstrate that Rivulus embryos have an efficient PR system and a caffeine-sensitive dark repair capacity. (author). 31 refs.; 5 figs

Ion yields in UV-MALDI mass spectrometry as a function of excitation laser wavelength and optical and physico-chemical properties of classical and halogen-substituted MALDI matrixes.

Science.gov (United States)

Soltwisch, Jens; Jaskolla, Thorsten W; Hillenkamp, Franz; Karas, Michael; Dreisewerd, Klaus

2012-08-07

The laser wavelength constitutes a key parameter in ultraviolet-matrix-assisted laser desorption ionization-mass spectrometry (UV-MALDI-MS). Optimal analytical results are only achieved at laser wavelengths that correspond to a high optical absorption of the matrix. In the presented work, the wavelength dependence and the contribution of matrix proton affinity to the MALDI process were investigated. A tunable dye laser was used to examine the wavelength range between 280 and 355 nm. The peptide and matrix ion signals recorded as a function of these irradiation parameters are displayed in the form of heat maps, a data representation that furnishes multidimensional data interpretation. Matrixes with a range of proton affinities from 809 to 866 kJ/mol were investigated. Among those selected are the standard matrixes 2,5-dihydroxybenzoic acid (DHB) and α-cyano-4-hydroxycinnamic acid (HCCA) as well as five halogen-substituted cinnamic acid derivatives, including the recently introduced 4-chloro-α-cyanocinnamic acid (ClCCA) and α-cyano-2,4-difluorocinnamic acid (DiFCCA) matrixes. With the exception of DHB, the highest analyte ion signals were obtained toward the red side of the peak optical absorption in the solid state. A stronger decline of the molecular analyte ion signals generated from the matrixes was consistently observed at the low wavelength side of the peak absorption. This effect is mainly the result of increased fragmentation of both analyte and matrix ions. Optimal use of multiply halogenated matrixes requires adjustment of the excitation wavelength to values below that of the standard MALDI lasers emitting at 355 (Nd:YAG) or 337 nm (N(2) laser). The combined data provide new insights into the UV-MALDI desorption/ionization processes and indicate ways to improve the analytical sensitivity.

Nonlinear propagation of short wavelength drift-Alfven waves

DEFF Research Database (Denmark)

Shukla, P. K.; Pecseli, H. L.; Juul Rasmussen, Jens

1986-01-01

Making use of a kinetic ion and a hydrodynamic electron description together with the Maxwell equation, the authors derive a set of nonlinear equations which governs the dynamics of short wavelength ion drift-Alfven waves. It is shown that the nonlinear drift-Alfven waves can propagate as two-dim...

Thermoluminescent properties of ZrO{sub 2}:Mn for UV light dosimetry; Propiedades termoluminiscentes de ZrO{sub 2}:Mn para dosimetria de la luz UV

Energy Technology Data Exchange (ETDEWEB)

Rivera M, T. [Universidad Autonoma Metropolitana Iztapalapa, Deparatmento de Fisica, 09340 Mexico D.F. (Mexico); Azorin N, J. [CICATA-IPN, 11500 Mexico D.F. (Mexico); Falcony G, C. [CINVESTAV-IPN, Departamento de Fisica, 07300 Mexico D.F. (Mexico); Martinez, E.; Garcia, M. [Universidad Nacional Autonoma de Mexico, Instituto de Investigaciones en Materiales, 04510 Mexico D.F. (Mexico)

1999-07-01

The main source of ultraviolet light (UV) to whom is exposed the population is the one coming from the Sun, although exist some artificial sources too. The UV light can be classified in UV A (315-400)nm, in UV B (180-315) nm and UV C (100-180) nm. In this work are presented the results studying in the thermoluminescent characteristics of ZrO{sub 2}: Mn for the UV dosimetry. The studied dosimetric characteristics were: concentration effect of the doping material, erased thermal treatment, posterior thermal treatment to the irradiation, Tl curve, response in function to the wavelength, response in function to the dose and reproducibility. Finally, presenting results highly promisers for the UV light dosimetry. (Author)

Effect of local UV irradiation of generative nuclei of Paramecium caudatum on sexual functions of the cells

International Nuclear Information System (INIS)

Skoblo, I.I.; Borkhsenius, O.N.

1979-01-01

The functions of micronucleus (MI) were studied in the period of the sexual process in Paramecium caudatum-infusoria the descendants of the cells, whose micronucleus was locally irradiated with UV rays at the dose of 3060 erg/mm 2 . It has been found that the descendants of the irradiated cells (the cells of UV clones) can be involved into the sexual process irrespoctive of the morphological type of their MI. Four out of forteen UV clones have changed the initial mating type for the opposite one. It is suggested that the change of the mating type is related to the changes of MI genome resulted from UV irradiation. The pathway of nuclear transformations in the course of sexual process was traced in cells of three UV clones. It has been found, that local UV irradiation of MI causes a number of deviations in the behaviour of MI derivatives in the metagamic part of the sexual process in the clones, whose MI have undergone substantial morphological changes. The exconjugants produced by crossing of UV clones with such changed MI and the normal test-clone were characterized by low viability

Effects of UV-B irradiation on isoforms of antioxidant enzymes and their activities in red alga Grateloupia filicina (Rhodophyta)

Science.gov (United States)

Zhao, Jiqiang; Li, Lixia

2014-11-01

Macroalgae in a littoral zone are inevitably exposed to UV-B irradiance. We analyzed the effects of UV-B on isoenzyme patterns and activities of superoxide dismutase (SOD), peroxidase (POX), catalase (CAT), and ascorbate peroxidase (APX) of red algae Grateloupia filicina (Lamour.) C. Agardh. The activities of SOD, CAT, and APX changed in response to UV-B in a time- and dose-dependent manner. POX activity increased significantly under all three UV-B treatments. The enzymatic assay showed three distinct bands of SODI (Mn-SOD), SODII (Fe-SOD), and SODIII (CuZn-SOD) under a low (Luv) and medium (Muv) dose of UV-B irradiation, while SODI and SODIII activities decreased significantly when exposed to a high dose of UV-B irradiation (Huv). The activity of POX isoenzymes increased significantly after exposure to UV-B, which is consistent with the total activity. In addition, a clear decrease in activity of CATIV was detected in response to all the three doses of UV treatments. Some bands of APX isoenzyme were also clearly influenced by UV-B irradiation. Correspondingly, the daily growth rate declined under all the three exposure doses, and was especially significant under Muv and Huv treatments. These data suggest that, although the protection mechanisms of antioxidant defense system are partly inducible by UV-B to prevent the damage, G. filicina has incomplete tolerance to higher UV-B irradiation stress.

UV irradiation analysis of complementation between, and replication of, RNA-negative temperature-sensitivie mutants of Newcastle disease virus

International Nuclear Information System (INIS)

Peeples, M.E.; Bratt, M.A.

1982-01-01

Random uv irradiation-induced lesions destroy the infectivity of Newcastle disease virus (NDV) by blocking downstream transcription from the single viral promoter. The nucleocapsid-associated polypeptides most likely to be involved in RNA synthesis are located at the extreme ends of the genome: NP and P are promoter proximal genes, and L is the most distal gene. We attempted to order the two temperature-sensitive (ts) RNA-negative (RNA-) mutant groups of NDV by determining the uv target sizes for the complementing abilities of mutants A1 and E1. After uv irradiation, E1 was unable to complement A1, a result compatible with the A mutation lying in the L gene. In contrast, after uv irradiation A1 was able to complement E1 for both virus production and viral protein synthesis, with a target size most consistent with the E mutation lying in the P gene. UV-irradiated virus was unable to replicate as indicated by its absence in the yields of multiply infected cells, either as infectious virus or as particles with complementing activity. After irradiation, ts mutant B1ΔP, with a non-ts mutation affecting the electrophoretic mobility of the P protein, complemented E1 in a manner similar to A1, but it did not amplify the expression of ΔP in infected cells. This too is consistent with irradiated virus being unable to replicate despite the presence of the components needed for replication of E1. At high uv doses, A1 was able to complement E1 in a different, uv-resistant manner, probably by direct donation of input polypeptides. Multiplicity reactivation has previously been observed at high-multiplicity infection by uv-irradiated paramyxoviruses. In this case, virions which are noninfectious because they lack a protein component may be activated by a protein from irradiated virions

Thermoluminescent properties of ZrO2:Mn for UV light dosimetry

International Nuclear Information System (INIS)

Rivera M, T.; Azorin N, J.; Falcony G, C.; Martinez, E.; Garcia, M.

1999-01-01

The main source of ultraviolet light (UV) to whom is exposed the population is the one coming from the Sun, although exist some artificial sources too. The UV light can be classified in UV A (315-400)nm, in UV B (180-315) nm and UV C (100-180) nm. In this work are presented the results studying in the thermoluminescent characteristics of ZrO 2 : Mn for the UV dosimetry. The studied dosimetric characteristics were: concentration effect of the doping material, erased thermal treatment, posterior thermal treatment to the irradiation, Tl curve, response in function to the wavelength, response in function to the dose and reproducibility. Finally, presenting results highly promisers for the UV light dosimetry. (Author)

Mitochondrial genetics X: Effects of UV irradiation on transmission and recombination of mitochondrial genes in Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Dujon, B.; Kruszewska, A.; Slonimski, P.P.; Bolotin-Fukuhara, M.; Coen, D.; Deutsch, J.; Netter, P.; Weill, L.

1975-01-01

UV irradiation has been applied either to one parent prior to crossing or to newly formed zygotes. The effects of UV have been studied on the transmission of mitochondrial alleles at the loci conferring resistance to antibiotic and the frequency of recombinants between various combinations of alleles at these loci. The effects of UV depend on the nature of the cross i.e. homosexual (ω + x ω + or ω - x ω - ) or heterosexual (ω + x ω - ). In all cases UV irradiation of one of the parents diminishes the transmission of the mitochondrial alleles originated from the irradiated parent. In homosexual crosses the decrease of transmission is the same for alleles at all the loci. In heterosexual crosses, when the ω + parent is irradiated, there is a differential decrease of transmission depending on the distance of the resistance locus relative to the ω locus. In heterosexual crosses irradiation of the ω + parent increases the frequency of recombinants while irradiation of the ω - parent slightly decreases it. In homosexual crosses the frequency of recombinants diminishes when a high UV dose is applied to one of the parents. No or only minor modifications of the polarity of recombination are observed. Irradiation of newly formed zygotes has no or minor effects on the transmission of alleles and recombinant frequencies. All these effects can be interpreted in terms of a general model for recombination of mitochondrial genes. UV irradiation of one of the parents leads to a modification of the input fraction in favor of the non irradiated parent. As a consequence of this modification the output of alleles and the frequency of recombinants are changed. A good quantitative agreement between the predictions calculated on the basis of the model and the experimental data is found. Relationships between the molecular events responsible for the modifications of input and the production of rho - primary clones by UV are discussed. (orig./MG) [de

Cytological evidence for DNA chain elongation after UV irradiation in the S phase

International Nuclear Information System (INIS)

Minka, D.F.; Nath, J.

1981-01-01

Human cells irradiated with UV light synthesize lower molecular weight DNA than unirradiated cells. This reduction in molecular weight is greater in xeroderma pigmentosum (XP) cells than in normal cells. The molecular weight of DNA is further reduced by the addition of caffeine to XP cells. By several hours after irradiation, DNA fragments are barely detectable. Cells from excision-proficient and excision-deficient XP patients were studied autoradiographically to produce cytological evidence of DNA chain elongation. Replicate cultures with and without caffeine were synchronized and irradiated with UV light during the S phase. Caffeine was removed in G2, and the cells were labeled with 3 H-thymidine. Results showed significantly increased labeling during G2 of excision-deficient XP cells. Labeling was dependent on the time of irradiation and presence of caffeine. The XP variant cells had no increase in labeling for any irradiation time

Efficacy of UV-irradiated larval vaccine of Ancylostoma ceylanicum (Looss, 1911) in golden hamsters (Merocricetus auratus)

International Nuclear Information System (INIS)

Menon, S.; Bhopale, M.K.

1985-01-01

A vaccination trial in golden hamsters with UV-irradiated infective larvae of Ancylostoma ceylanicum was attempted. One oral vaccination of hamsters with 100 infective larvae irradiated by means of UV-tube (390 nm) at different time intervals induced the development of resistance. As the time exposure of irradiation was increased, there was a corresponding decrease in the subsequent worm establishment. A high level of protection afforded by larvae irradiated for 15 min UV-exposure was recorded giving 99.0% and 95.0% worm reduction against the challenge doses of 100 and 1000 normal larvae respectively. There was no marked difference in worm establishment in hamsters vaccinated either orally or subcutaneously, followed by oral challenge. In the vaccinated hamsters, the manifestations of resistance at 15 min UV-exposure were shown by marked reduction in worm establishment and highly reduced epg in pellets with significantly higher blood haemoglobin levels compared with those given normal larvae as vaccine and challenge controls. (author)

Activation of Peroxisome Proliferator-Activated Receptor Alpha Improves Aged and UV-Irradiated Skin by Catalase Induction.

Science.gov (United States)

Shin, Mi Hee; Lee, Se-Rah; Kim, Min-Kyoung; Shin, Chang-Yup; Lee, Dong Hun; Chung, Jin Ho

2016-01-01

Peroxisome proliferator-activated receptor alpha (PPARα) is a nuclear hormone receptor involved in the transcriptional regulation of lipid metabolism, fatty acid oxidation, and glucose homeostasis. Its activation stimulates antioxidant enzymes such as catalase, whose expression is decreased in aged human skin. Here we investigated the expression of PPARα in aged and ultraviolet (UV)-irradiated skin, and whether PPARα activation can modulate expressions of matrix metalloproteinase (MMP)-1 and procollagen through catalase regulation. We found that PPARα mRNA level was significantly decreased in intrinsically aged and photoaged human skin as well as in UV-irradiated skin. A PPARα activator, Wy14643, inhibited UV-induced increase of MMP-1 and decrease of procollagen expression and caused marked increase in catalase expression. Furthermore, production of reactive oxygen species (ROS) was suppressed by Wy14643 in UV-irradiated and aged dermal fibroblasts, suggesting that the PPARα activation-induced upregulation of catalase leads to scavenging of ROS produced due to UV irradiation or aging. PPARα knockdown decreased catalase expression and abolished the beneficial effects of Wy14643. Topical application of Wy14643 on hairless mice restored catalase activity and prevented MMP-13 and inflammatory responses in skin. Our findings indicate that PPARα activation triggers catalase expression and ROS scavenging, thereby protecting skin from UV-induced damage and intrinsic aging.

Optical Detection in Ultrafast Short Wavelength Science

International Nuclear Information System (INIS)

Fullagar, Wilfred K.; Hall, Chris J.

2010-01-01

A new approach to coherent detection of ionising radiation is briefly motivated and recounted. The approach involves optical scattering of coherent light fields by colour centres in transparent solids. It has significant potential for diffractive imaging applications that require high detection dynamic range from pulsed high brilliance short wavelength sources. It also motivates new incarnations of Bragg's X-ray microscope for pump-probe studies of ultrafast molecular structure-dynamics.

Thermal helix-coil transition in UV irradiated collagen from rat tail tendon.

Science.gov (United States)

Sionkowska, A; Kamińska, A

1999-05-01

The thermal helix-coil transition in UV irradiated collagen solution, collagen film and pieces of rat tail tendon (RTT) were compared. Their thermal stability's were determined by differential scanning calorimeter (DSC) and by viscometric measurements. The denaturation temperatures of collagen solution, film and pieces of RTT were different. The helix-coil transition occur near 40 degrees C in collagen solution, near 112 degrees C in collagen film, and near 101 degrees C in pieces of RTT. After UV irradiation the thermal helix-coil transition of collagen samples were changed. These changes depend on the degree of hydratation.

UV dissociation of vibrationally excited UF6

International Nuclear Information System (INIS)

Alexandre, M.; Clerc, M.; Gagnon, R.; Gilbert, M.; Isnard, P.; Nectoux, P.; Rigny, P.; Weulersse, J.M.

1983-01-01

Before application of laser photodissociation of UF 6 to the separation of uranium isotopes becomes practical, isotopic selectivity should be optimized. We present here results on the cross sections involved in the irradiation of UF 6 simultaneously with infrared and ultraviolet lasers, as a function of wavelengths, fluence and temperature (at 293 K and 105 K, in an adiabatic expansion). The experiment uses a Nd 3+ YAG pumped lithium niobate optical parametric oscillator as a tunable 16 μ light source. Energies of the order of 1 mJ can be obtained with linewidths smaller than 0.1 cm - . The UV source used is based on ND 3+ YAG pumped dye laser and various frequency mixing schemes. At low temperature the frequency variation of the absorbed infrared energy per molecule depends markedly on the IR fluence phisub(IR) with a maximum value varying as phisub(IR)sup(-1/2) and a frequency extension far beyond the low level absorption spectrum. The absorbed vibrational energy leads to a change in the UV cross section comparable with the effect of a rise in temperature. Using this a model is put forward to express the isotopic selectivity 235 U/ 238 U as a function of UV wavelength and IR irradiation conditions. Experimental results agree with this model, and yield to maximum selectivity close to two [fr

Repair of radiation damage of Micrococcus radioproteolyticus due to gamma and UV irradiation

International Nuclear Information System (INIS)

Ryznar, L.; Drasil, V.

1982-01-01

Cells were irradiated in dry state with gamma radiation and UV radiation. The post-irradiation warming of freeze dried cells (2 hours to 60deg or to 80deg) influenced the ability to repair sublethal damage. Heating to 80deg caused a mild reduction in survival. The repair of irradiated and heated cells required more time than that of cells which had only been irradiated. (M.D.)

Inhibition of Escherichia coli respiratory enzymes by short visible femtosecond laser irradiation

International Nuclear Information System (INIS)

Lu, Chieh-Han; Hsu, Yung-Yuan; Lin, Kung-Hsuan; Tsen, Kong-Thon; Kuan, Yung-Shu

2014-01-01

A visible femtosecond laser is shown to be capable of selectively inactivating a wide spectrum of microorganisms in a wavelength and pulse width dependent manner. However, the mechanism of how a visible femtosecond laser affects the viability of different microorganisms is still elusive. In this paper, the cellular surface properties, membrane integrity and metabolic rate of Escherichia coli (E. coli) irradiated by a visible femtosecond laser (λ = 415 nm, pulse width = 100 fs) with different exposure times were investigated. Our results showed that femtosecond laser treatment for 60 min led to cytoplasmic leakage, protein aggregation and alternation of the physical properties of the E. coli cell membrane. In comparison, a 10 min exposure of bacteria to femtosecond laser irradiation induced an immediate reduction of 75% in the glucose-dependent respiratory rate, while the cytoplasmic leakage was not detected. Results from enzymatic assays showed that oxidases and dehydrogenases involved in the E. coli respiratory chain exhibited divergent susceptibility after laser irradiation. This early commencement of respiratory inhibition after a short irradiation is presumed to have a dominant effect on the early stage of bacteria inactivation. (paper)

Alternative strawberry disease management strategy: combing low UV-C irradiation in dark, disabling pathogen’s UV-C repair mechanism, and preventing pathogen establishment with biocontrol agents

Science.gov (United States)

The limitations of current fungicides necessitate a search for new approaches. Low-dose or sub-lethal UV-C irradiation (12.36 J/m2) alone is not effective in controlling fungal diseases, especially when the plants are exposed to UV-C irradiation during the day. We found, however, that application ...

Treating cell culture media with UV irradiation against adventitious agents: minimal impact on CHO performance.

Science.gov (United States)

Yen, Sandi; Sokolenko, Stanislav; Manocha, Bhavik; Blondeel, Eric J M; Aucoin, Marc G; Patras, Ankit; Daynouri-Pancino, Farnaz; Sasges, Michael

2014-01-01

Sterility of cell culture media is an important concern in biotherapeutic processing. In large scale biotherapeutic production, a unit contamination of cell culture media can have costly effects. Ultraviolet (UV) irradiation is a sterilization method effective against bacteria and viruses while being non-thermal and non-adulterating in its mechanism of action. This makes UV irradiation attractive for use in sterilization of cell culture media. The objective of this study was to evaluate the effect of UV irradiation of cell culture media in terms of chemical composition and the ability to grow cell cultures in the treated media. The results showed that UV irradiation of commercial cell culture media at relevant disinfection doses impacted the chemical composition of the media with respect to several carboxylic acids, and to a minimal extent, amino acids. The cumulative effect of these changes, however, did not negatively influence the ability to culture Chinese Hamster Ovary cells, as evaluated by cell viability, growth rate, and protein titer measurements in simple batch growth compared with the same cells cultured in control media exposed to visible light. © 2014 The Authors. Published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers.

The formation of space network in structure of polyallyl cinnamates under UV- and γ-irradiation

International Nuclear Information System (INIS)

Yagudeev, T.

2003-01-01

Influence of UV- and γ-irradiation on polyallyl cinnamates (PAC) structure are investigated. UV-irradiation of polymers samples carried out by lamp PRK-2 at 25-30 deg. C.; 60 Co was used for γ-irradiation: mean value of dose power - 50 μR/s; average energy of γ-quantum E γ =1.25 MeV. It was shown that under various kinds of irradiation polyallyl cinnamates forms space networks and samples of PAC kept itself physico-mechanical properties (light transparent - 90 %), or increase its (microhardness reach 150 %). It can be concluded that such polymers may find application for creation of elements of laser optics

Investigation of concept of efficient short wavelength laser. Final technical report, April 1, 1977-July 31, 1979

International Nuclear Information System (INIS)

Piper, L.G.; Krech, R.H.; Pugh, E.; Taylor, R.L.

1979-01-01

The feasibility of producing an efficient, short wavelength, storage laser for ICF driven applications by making use of certain state-specific reactions of exoergic azide compounds has been investigated. The ultraviolet (approx. 300 nm) photolysis of gaseous ClN 3 produced prompt emission in the red, which was attributed to the efficient formation of ClN(b 1 Σ + ) with subsequent ClN(X reverse arrow b) fluorescence. Based on these results, a small-scale laser demonstration experiment was constructed using short duration Xe flash lamps as the photolytic source. The results of this latter experiment were negative. The most plausible explanation was that the flash lamps provided sufficient far-uv radiation to dissociate and/or ionize the ClN(b) produced in the primary photolytic step. In parallel, limited experiments were performed on the rapid pyrolysis of a solid, ionic azide, NaN 3 , to produce gaseous N 3 radicals and subsequent production of triplet N 2 molecules

Photomimetic effect of serotonin on yeast cells irradiated by far-UV radiation

International Nuclear Information System (INIS)

Fraikin, G.Y.; Strakhovskaya, M.G.; Rubin, L.B.

1982-01-01

The effect of serotonin on the survival of far-UV irradiated cells of the yeast Candida guilliermondii was studied. Serotonin was found to have a photomimetic property. Preincubation of cells with serotonin results in protection against far-UV inactivation, whereas the post-radiation treatment with serotonin causes a potentiation of far-UV lethality. Both effects are similar to those produced by near-UV (334 nm) radiation. The observations provide support to the previously proposed idea that photosynthesized serotonin is the underlying cause of the two effects of near-UV radiation, photoprotection and potentiation of far-UV lethality. Experiments with an excision-deficient strain of the yeast Saccharomyces cerevisiae suggest that the effect of serotonin is by its binding to DNA. (author)

Dermal damage promoted by repeated low-level UV-A1 exposure despite tanning response in human skin.

Science.gov (United States)

Wang, Frank; Smith, Noah R; Tran, Bao Anh Patrick; Kang, Sewon; Voorhees, John J; Fisher, Gary J

2014-04-01

exposures did not suppress type I procollagen expression. A limited number of low-dose UV-A1 exposures, as commonly experienced in daily life, potentially promotes photoaging by affecting breakdown, rather than synthesis, of collagen. Progressive skin darkening in response to repeated low-dose UV-A1 exposures in lightly pigmented individuals does not prevent UV-A1-induced collagenolytic changes. Therefore, for optimal protection against skin damage, sunscreen formulations should filter all UV wavelengths, including UV-A1 irradiation.

Probing behaviors of Sitobion avenae (Hemiptera: Aphididae on enhanced UV-B irradiated plants

Directory of Open Access Journals (Sweden)

Hu Zu-Qing

2013-01-01

Full Text Available UV-B induced changes in plants can influence sap-feeding insects through mechanisms that have not been studied. Herein the grain aphid, Sitobion avenae (Fabricius (Hemiptera: Aphididae, was monitored on barley plants under the treatments of control [0 kJ/ (m2.d], ambient UV-B [60 kJ/ (m2.d], and enhanced UV-B [120 kJ/ (m2.d] irradiation. Electrical penetration graph (EPG techniques were used to record aphid probing behaviors. Enhanced UV-B irradiated plants negatively affected probing behaviors of S. avenae compared with control plants. In particular, phloem factors that could diminish sieve element acceptance appeared to be involved, as reflected by smaller number of phloem phase, shorter phloem ingestion, and fewer aphids reaching the sustained phloem ingestion phase (E2>10min. On the other hand, factors from leaf surface, epidermis, and mesophyll cannot be excluded, as reflected by higher number of non-probing, longer non-probing and pathway phase, and later the time to first probe.

UV-visible absorbance spectroscopy as a proxy for peatland dissolved organic carbon (DOC) quantity and quality: considerations on wavelength and absorbance degradation.

Science.gov (United States)

Peacock, Mike; Evans, Chris D; Fenner, Nathalie; Freeman, Chris; Gough, Rachel; Jones, Timothy G; Lebron, Inma

2014-05-01

Absorbance in the UV or visible spectrum (UV-vis) is commonly used as a proxy for DOC concentrations in waters draining upland catchments. To determine the appropriateness of different UV-vis measurements we used surface and pore water samples from two Welsh peatlands in four different experiments: (i) an assessment of single wavelength proxies (1 nm increments between 230-800 nm) for DOC concentration demonstrated that 254 nm was more accurate than 400 nm. The highest R(2) values between absorbance and DOC concentration were generated using 263 nm for one sample set (R(2) = 0.91), and 230 nm for the other three sample sets (respective R(2) values of 0.86, 0.81, and 0.93). (ii) A comparison of different DOC concentration proxies, including single wavelength proxies, a two wavelength model, a proxy using phenolic concentration, and a proxy using the area under a UV spectrum at 250-350 nm. It was found that both a single wavelength proxy (≤263 nm) and a two wavelength model performed well for both pore water and surface water. (iii) An evaluation of the E2 : E3, E2 : E4, E4 : E6 ratios, and SUVA (absorbance at 254 nm normalised to DOC concentration) as indicators of DOC quality showed that the E4 : E6 ratio was subject to extensive variation over time, and was highly correlated between surface water and pore water, suggesting that it is a useful metric to determine temporal changes in DOC quality. (iv) A repeated weekly analysis over twelve weeks showed no consistent change in UV-vis absorbance, and therefore an inferred lack of degradation of total DOC in samples that were filtered and stored in the dark at 4 °C.

Drop and recovery of thermal conductivity of AlN upon UV irradiation

International Nuclear Information System (INIS)

AlShaikhi, A; Srivastava, G P

2007-01-01

We have performed calculations of the room-temperature thermal conductivity of oxygen contaminated aluminium nitride (AlN) by employing the Callaway model with a detailed account of three-phonon scattering processes. The role of Al vacancy and O substitution of N has been examined in the form of extended defects (clusters) and point defects. Our work provides support for the theoretical model proposed by Harris et al. [Phys. Rev. B. 47, 5428 (1993)] to explain the experimentally observed drop in the conductivity upon UV irradiation and its recovery upon UV removal and subsequent illumination of the sample with visible light at room temperature. With the reported oxygen concentration in the sample, the scattering of phonons from oxygen-related extended defects is found to be ineffective. Within the picture presented by Harris et al., the point impurity scattering parameter increases by around 17% upon UV irradiation of the sample at room temperature

Short wavelength striations on expanding plasma clouds

International Nuclear Information System (INIS)

Winske, D.; Gary, S.P.

1989-01-01

The growth and evolution of short wavelength (< ion gyroradius) flute modes on a plasma expanding across an ambient magnetic field have been actively studied in recent years, both by means of experiments in the laboratory as well as in space and through numerical simulations. We review the relevant observations and simulations results, discuss the instability mechanism and related linear theory, and describe recent work to bring experiments and theory into better agreement. 30 refs., 6 figs

Zinc finger protein 598 inhibits cell survival by promoting UV-induced apoptosis.

Science.gov (United States)

Yang, Qiaohong; Gupta, Romi

2018-01-19

UV is one of the major causes of DNA damage induced apoptosis. However, cancer cells adopt alternative mechanisms to evade UV-induced apoptosis. To identify factors that protect cancer cells from UV-induced apoptosis, we performed a genome wide short-hairpin RNA (shRNA) screen, which identified Zinc finger protein 598 (ZNF598) as a key regulator of UV-induced apoptosis. Here, we show that UV irradiation transcriptionally upregulates ZNF598 expression. Additionally, ZNF598 knockdown in cancer cells inhibited UV-induced apoptosis. In our study, we observe that ELK1 mRNA level as well as phosphorylated ELK1 levels was up regulated upon UV irradiation, which was necessary for UV irradiation induced upregulation of ZNF598. Cells expressing ELK1 shRNA were also resistant to UV-induced apoptosis, and phenocopy ZNF598 knockdown. Upon further investigation, we found that ZNF598 knockdown inhibits UV-induced apoptotic gene expression, which matches with decrease in percentage of annexin V positive cell. Similarly, ectopic expression of ZNF598 promoted apoptotic gene expression and also increased annexin V positive cells. Collectively, these results demonstrate that ZNF598 is a UV irradiation regulated gene and its loss results in resistance to UV-induced apoptosis.

Occurrence and elimination of sites sensitive to UV-endonuclease in UV-irradiated E. coli cells

Energy Technology Data Exchange (ETDEWEB)

Kleibl, K; Sedliakova, M [Slovenska Akademia Vied, Bratislava (Czechoslovakia). Vyskumny Ustav Onkologicky

1979-01-01

The occurrence and elimination of sites sensitive to the endonucleolytic action of crude extract from M. luteus (Es sites) were studied in both the parental and daughter DNA of E. coli B/r Hcr/sup +/ irradiated either with lethal fluence only (LF) or with inducing and lethal fluence (IF+LF); after the lethal fluence protein synthesis could either take place or it was inhibited by chlorampehnicol (CAP). The data obtained showed that in the wild type UV-irradiated cells Es sites could be eliminated from their DNA molecules either through pyrimidine dimer excision or through the modification of dimers on replication. It appears that DNA repair takes place most efficiently in cells irradiated with IF+LF and postincubated with CAP; in these conditions cells are supplied with inducible proteins, and enough time for DNA repair is provided before the division of irradiated cells is resumed.

Adverse Effects of UV-B Radiation on Plants Growing at Schirmacher Oasis, East Antarctica.

Science.gov (United States)

Singh, Jaswant; Singh, Rudra P

2014-01-01

This study aimed to assess the impacts of ultraviolet-B (UV-B) radiation over a 28-day period on the levels of pigments of Umbilicaria aprina and Bryum argenteum growing in field. The depletion of stratospheric ozone is most prominent over Antarctica, which receives more UV-B radiation than most other parts of the planet. Although UV-B radiation adversely affects all flora, Antarctic plants are better equipped to survive the damaging effects of UV-B owing to defenses provided by UV-B absorbing compounds and other screening pigments. The UV-B radiations and daily average ozone values were measured by sun photometer and the photosynthetic pigments were analyzed by the standard spectrophotometric methods of exposed and unexposed selected plants. The daily average atmospheric ozone values were recorded from 5 January to 2 February 2008. The maximum daily average for ozone (310.7 Dobson Units (DU)) was recorded on 10 January 2008. On that day, average UV-B spectral irradiances were 0.016, 0.071, and 0.186 W m(-2) at wavelengths of 305, 312, and 320 nm, respectively. The minimum daily average ozone value (278.6 DU) was recorded on 31 January 2008. On that day, average UV-B spectral irradiances were 0.018, 0.085, and 0.210 W m(-2) at wavelengths of 305, 312, and 320 nm, respectively. Our results concludes that following prolonged UV-B exposure, total chlorophyll levels decreased gradually in both species, whereas levels of UV-B absorbing compounds, phenolics, and carotenoids gradually increased.

Specific racemization and isomerization of the aspartyl residue of αA-crystallin due to UV-B irradiation

International Nuclear Information System (INIS)

Fujii, Noriko; Momose, Yuko; Ishibasi, Yoshihiro; Uemura, Toshimasa; Takita, Masatoshi; Takehana, Makoto

1997-01-01

We have reported that the aspartyl (Asp)-151 residue in αA-crystallin in human eye lens was inverted to the D-isomer and isomerized to β-Asp residue with age. We report here that ultraviolet (UV)-B irradiation induces the racemization and isomerization of the Asp-151 residue of αA-crystallin from lenses of 6-week-old rats to form D-isomer and β-Asp residue. Simultaneous racemization and isomerization of the specific Asp residue indicate that the reaction proceeds via formation of a succinimide intermediate. This modification was not observed in UV-A irradiated and normal lenses. UV-B irradiation induced the racemization of only the Asp-151 residue and did not affect the other Asp residues in αA-crystallin. On the other hand, the high molecular weight fraction of the lens protein increased upon UV-B irradiation. Modification of the Asp residue would affect the three-dimensional packing array of the lens protein. (author)

U.V. irradiation inhibits the electrical block to polyspermy in echinoderms

International Nuclear Information System (INIS)

David, C.; Moreau, M.; Vilain, J.P.; Guerrier, P.

1985-01-01

Oocytes of the sea urchin Sphaerechinus granularis and the starfish Marthasterias glacialis have been submitted to U.V. irradiation before fertilization. This treatment significantly increased the incidence and severity of polyspermy in the sea urchin and was also found effective on starfish oocytes. These were found more resistant to damage than sea urchin eggs and U.V. irradiation did not affect either their response to the hormone l-methyladenine or the rate of elevation of the fertilization envelope, which assures the late and definitive block to polyspermy. Electrophysiological measurements performed on M. glacialis oocytes definitively demonstrate that U.V. irradiation completely inactivates voltage-dependent sodium channels, without altering the other main conductances, Cl - , K + or Ca 2+ . After such a treatment, the relative permeability of the membrane to Na + as compared to K + shifted from 0.019+-0.003 to 0.003+-0.002 and only the calcium component of the action potentials could be observed. However, a fertilization potential, preceded by small sperm induced steps, is still present in these conditions, although its peak and plateau level are greatly reduced. These new findings are discussed, which confirm the electrical nature of the fast block to polyspermy but question about the specificity of those sperm-gated channels which are supposed to trigger the fertilization potential. (author)

Solar UV radiation variations and their stratospheric and climatic effects

Science.gov (United States)

Donnelly, R. F.; Heath, D. F.

1985-01-01

Nimbus-7 SBUV measurements of the short-term solar UV variations caused by solar rotation and active-region evolution have determined the amplitude and wavelength dependence for the active-region component of solar UV variations. Intermediate-term variations lasting several months are associated with rounds of major new active regions. The UV flux stays near the peak value during the current solar cycle variation for more than two years and peaks about two years later than the sunspot number. Nimbus-7 measurements have observed the concurrent stratospheric ozone variations caused by solar UV variations. There is now no doubt that solar UV variations are an important cause of short- and long-term stratospheric variations, but the strength of the coupling to the troposphere and to climate has not yet been proven.

Selective ablation of photovoltaic materials with UV laser sources for monolithic interconnection of devices based on a-Si:H

Energy Technology Data Exchange (ETDEWEB)

Molpeceres, C. [Centro Laser UPM, Univ. Politecnica de Madrid, Crta. de Valencia Km 7.3, 28031 Madrid (Spain)], E-mail: carlos.molpeceres@upm.es; Lauzurica, S.; Garcia-Ballesteros, J.J.; Morales, M.; Guadano, G.; Ocana, J.L. [Centro Laser UPM, Univ. Politecnica de Madrid, Crta. de Valencia Km 7.3, 28031 Madrid (Spain); Fernandez, S.; Gandia, J.J. [Dept. de Energias Renovables, Energia Solar Fotovoltaica, CIEMAT, Avda, Complutense 22, 28040 Madrid (Spain); Villar, F.; Nos, O.; Bertomeu, J. [CeRMAE Dept. Fisica Aplicada i Optica, Universitat de Barcelona, Av. Diagonal 647, 08028 Barcelona (Spain)

2009-03-15

Lasers are essential tools for cell isolation and monolithic interconnection in thin-film-silicon photovoltaic technologies. Laser ablation of transparent conductive oxides (TCOs), amorphous silicon structures and back contact removal are standard processes in industry for monolithic device interconnection. However, material ablation with minimum debris and small heat affected zone is one of the main difficulty is to achieve, to reduce costs and to improve device efficiency. In this paper we present recent results in laser ablation of photovoltaic materials using excimer and UV wavelengths of diode-pumped solid-state (DPSS) laser sources. We discuss results concerning UV ablation of different TCO and thin-film silicon (a-Si:H and nc-Si:H), focussing our study on ablation threshold measurements and process-quality assessment using advanced optical microscopy techniques. In that way we show the advantages of using UV wavelengths for minimizing the characteristic material thermal affection of laser irradiation in the ns regime at higher wavelengths. Additionally we include preliminary results of selective ablation of film on film structures irradiating from the film side (direct writing configuration) including the problem of selective ablation of ZnO films on a-Si:H layers. In that way we demonstrate the potential use of UV wavelengths of fully commercial laser sources as an alternative to standard backscribing process in device fabrication.

Selective ablation of photovoltaic materials with UV laser sources for monolithic interconnection of devices based on a-Si:H

International Nuclear Information System (INIS)

Molpeceres, C.; Lauzurica, S.; Garcia-Ballesteros, J.J.; Morales, M.; Guadano, G.; Ocana, J.L.; Fernandez, S.; Gandia, J.J.; Villar, F.; Nos, O.; Bertomeu, J.

2009-01-01

Lasers are essential tools for cell isolation and monolithic interconnection in thin-film-silicon photovoltaic technologies. Laser ablation of transparent conductive oxides (TCOs), amorphous silicon structures and back contact removal are standard processes in industry for monolithic device interconnection. However, material ablation with minimum debris and small heat affected zone is one of the main difficulty is to achieve, to reduce costs and to improve device efficiency. In this paper we present recent results in laser ablation of photovoltaic materials using excimer and UV wavelengths of diode-pumped solid-state (DPSS) laser sources. We discuss results concerning UV ablation of different TCO and thin-film silicon (a-Si:H and nc-Si:H), focussing our study on ablation threshold measurements and process-quality assessment using advanced optical microscopy techniques. In that way we show the advantages of using UV wavelengths for minimizing the characteristic material thermal affection of laser irradiation in the ns regime at higher wavelengths. Additionally we include preliminary results of selective ablation of film on film structures irradiating from the film side (direct writing configuration) including the problem of selective ablation of ZnO films on a-Si:H layers. In that way we demonstrate the potential use of UV wavelengths of fully commercial laser sources as an alternative to standard backscribing process in device fabrication.

Choice of Eye-Safe Radiation Wavelength in UV and Near IR Spectral Bands for Remote Sensing

OpenAIRE

M. L. Belov; V. A. Gorodnichev; D. A. Kravtsov; A. A. Cherpakova

2016-01-01

The introduction of laser remote sensing systems carries a particular risk to the human’s sense of vision. A structure of the eye, and especially the retina, is the main critical organ as related to the laser radiation.The work uses the optical models of the atmosphere, correctly working in both the UV and the near-IR band, to select the eye-safe radiation wavelengths in the UV (0.355 m) and near-IR (~ 1.54 and ~ 2 m) spectral bands from the point of view of recorded lidar signal value to ful...

Depression of pyrimidine dimer excision from the aspects of U.V. reversibility of irradiated cells

International Nuclear Information System (INIS)

Slamenova, D.; Slezarikova, V.; Masek, F.

1977-01-01

Depression of pyrimidine dimer excision induced in U.V. irradiated E.coli B/r T - trp - Hcr + cells by preirradiation cultivation in conditions of starving for the essential amino acid and thymine does not increase U.V.-reversibility of irradiated cells and does not influence the time of expression of trp + reversions. The expression of mutations becomes completed in control and prestarved cells prior to restoration of postradiation division. Genetic deficiency leads up to their high sensitivity to the mutagenic activity of U.V. irradiation. Expression of trp + revertants in Hcr - type cells does not become completed until after commencement of the postradiation division of irradiated cells. Prestarved E.coli B/r T - trp - Hcr + cells exhibited depression of excision even with postradiation cultivation in the absence of an essential amino acid, which is associated with greater stability of newly synthesized DNA and overall decrease of the death rate of cells. In postradiation starvation for the essential amino acid E.coli B/r T - trp - Hcr - cells irradiated with low U.V. light doses behaved similarly. Control E.coli B/r T - trp - Hcr + cells, cultivated after irradiation without amino acid, excised pyrimidine dimers; they are characterised by high degradation of newly synthesized DNA and increased death rate of cells. (author)

Plant's adaptive response under UV-B-radiation influence

International Nuclear Information System (INIS)

Danil'chenko, O.A.; Grodzinskij, D.M.

2002-01-01

Reduction of ozone layer, owing to anthropogenic contamination of an atmosphere results in increase of intensity of UV-radiation and shift of its spectrum in the short-wave side that causes strengthening of various biological effects of irradiation. Consequences of these processes may include increase of injuring of plants and decrease of productivity of agricultural crops to increased UV levels. The important significance in the plant's adaptation to different unfavorable factors has the plant's radioadaptive answer. It has been shown that radioadaptation of plants occurred not only after irradiation with g-radiation in low doses but after UV-rays action . Reaction of radioadaptation it seems to be nonspecific phenomenon in relation to type radiations

Sterilization of Escherichia coli by using near-UV LED and TiO{sub 2} nanofibers that were prepared by using electrostatic spray

Energy Technology Data Exchange (ETDEWEB)

Lee, Dong-Gil; Hong, Ji-Tae; Son, Min-Kyu; Lee, Kyoung-Jun; Xu, Guo-Cheng; Prabakar, Kandasamy; Kim, Hee-je, E-mail: heeje@pusan.ac.k [Department of Electrical Engineering Pusan National University, 30 Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of)

2010-05-01

TiO{sub 2} nanofiber films were prepared by a homemade electrostatic spray method at 13 kV using a high power supply. As-prepared TiO{sub 2} was used to sterilize enteropathogenic Escherichia coli in polluted water by using near-UV LEDs at three different wavelengths with variable exposure time and frequency of irradiation. Irrespective of the wavelength of the light source used, longer irradiation times such as 1 h completely inactivated the E. coli. However, a wavelength of 375 nm was effective in inactivating in a shorter irradiation time (15 min). When the frequency of irradiation was 1 kHz, almost 95% of the E. coli was inactivated after 30 min exposure.

Comparative study of effects of neutron, γ-ray and UV irradiation on proteins

International Nuclear Information System (INIS)

Fujii, Noriko; Saito, Takeshi; Sakurai, Yoshinori; Shimada, Akihiko

2005-01-01

When α-crystalline was irradiated by γ-ray, isomerization of aspartic acid (Asp)-151 and oxidation of methionine(Met)-1 of αA-chain was introduced and the forth dimension structure of α-crystalline was changed. The chaperone-like activity decreased. By UV irradiation, the hydrophobic property of α-crystalline surface was decreased, isomerization of Asp-151 and oxidation of Met-1 of αA-chain introduced. The chaperon-like activity decreased, too. With irradiating neutron, oxidation of Trp and Met residue groups and cut of peptide bonds of α-crystalline was observed, but the chaperon-like activity was kept. The behaviors of charge particles produced by neutron, γ-ray and nuclear reactions were simulated. The effects of proton originated chlorine in the buffer solution on the behavior were very large. Metallothionein (Mt) was derived in the cell by treating γTN-1 with ZnCl 2 . The resistance of αTN4-1 to UV-A irradiation was increased by MT induced ZnCl 2 treatment. D-tryptophan was decomposed by tryptophanase irradiated with γ-ray. (S.Y.)

Inhibition of cyclobutane pyrimidine dimer formation in epidermal p53 gene of UV-irradiated mice by alpha-tocopherol

International Nuclear Information System (INIS)

Chen, W.; Barthelman, M.; Martinez, J.; Alberts, D.; Gensler, H.L.

1997-01-01

Mutations or alterations in the p53 gene have been observed in 50-100% of ultraviolet light (UV)-induced squamous cell carcinoma in humans and animals. Most of the mutations occurred at dipyrimidine sequences, suggesting that pyrimidine dimers in the p53 gene play a role in the pathogenesis of cutaneous squamous cell carcinoma. We previously showed that topical alpha-tocopherol prevents UV-induced skin carcinogenesis in the mouse. In the present study we asked whether topical alpha-tocopherol reduces the level of UV-induced cyclobutane pyrimidine dimers in the murine epidermal p53 gene. Mice received six dorsal applications of 25 mg each of alpha-tocopherol, on alternate days, before exposure to 500 J/m2 of UV-B irradiation. Mice were killed at selected times after irradiation. The level of dimers in the epidermal p53 gene was measured using the T4 endonuclease V assay with quantitative Southern hybridization. Topical alpha-tocopherol caused a 55% reduction in the formation of cyclobutane pyrimidine dimers in the epidermal p53 gene. The rate of reduction of pyrimidine dimers between 1 and 10 hours after irradiation was similar in UV-irradiated mice, regardless of alpha-tocopherol treatment. Therefore, the lower level of cyclobutane pyrimidine dimers in UV-irradiated mice treated with alpha-tocopherol than in control UV-irradiated mice resulted from the prevention of formation of the dimers, and not from enhanced repair of these lesions. Our results indicate that alpha-tocopherol acts as an effective sunscreen in vivo, preventing the formation of premutagenic DNA lesions in a gene known to be important in skin carcinogenesis

Variability of the nucleoli number in the progenies of intact and UV-irradiated clonogenic Hela cells

International Nuclear Information System (INIS)

Kucheryavaya, N.A.; Zavol'naya, E.S.; Vakhtin, Yu.B.

1981-01-01

The coefficient of the ''nucleoli number'' character heritability (h 2 ) in the population of intact Hela cells equals 0.21 to 0.33. UV-irradiation enhances almost equally both the intraclonic and population variability of the nucleoli number and, as a result, the coefficient of the ''nucleoli number'' character heritability does not change in the population of UV-irradiated Hela cells

Effect of UV-B irradiance on the ATP content of microorganisms of the Weddell Sea (Antartica)

International Nuclear Information System (INIS)

Vosjan, J.H.; Nieuwland, G.; Doehler, G.

1990-01-01

The effect of UV-B irradiation on the ATP content of natural assemblages of planktonic microorganisms in the upper 30-m water layer of the Weddell Sea (Antartica) was studied. After five hours of irradiation with UV (290-320 nm) of 1.35 W.m -2 a 75% decrease in the ATP content of the microorganisms was observed. (author). 11 refs.; 3 figs

Effects of Vinification Techniques Combined with UV-C Irradiation on Phenolic Contents of Red Wines.

Science.gov (United States)

Tahmaz, Hande; Söylemezoğlu, Gökhan

2017-06-01

Red wines are typically high in phenolic and antioxidant capacity and both of which can be increased by vinification techniques. This study employed 3 vinification techniques to assess the increase in phenolic compounds and antioxidant capacity. Wines were obtained from Boğazkere grape cultivar by techniques of classical maceration, cold maceration combined with ultraviolet light (UV) irradiation, and thermovinification combined with UV irradiation and changes in phenolic contents were examined. Total phenolic and anthocyanin contents and trolox equivalent antioxidant capacity of wines were measured spectrophotometrically and phenolic contents (+)-catechin, (-)-epicatechin, rutin, quercetin, trans-resveratrol, and cis-resveratrol were measured by High Pressure Liquid Chromatography with Diode Array Detection (HPLC-DAD). As a result of the study, the highest phenolic content except for quercetin was measured in the wines obtained by thermovinification combined with UV irradiation. We demonstrated that the highest phenolic compounds with health effect, total phenolic compounds, total anthocyanin, and antioxidant activity were obtained from thermovinification with UV-C treatment than classical wine making. © 2017 Institute of Food Technologists®.

Filtration–UV irradiation as an option for mitigating the risk of microbiologically influenced corrosion of subsea construction alloys in seawater

International Nuclear Information System (INIS)

Machuca, Laura L.; Jeffrey, Robert; Bailey, Stuart I.; Gubner, Rolf; Watkin, Elizabeth L.J.; Ginige, Maneesha P.; Kaksonen, Anna H.; Heidersbach, Krista

2014-01-01

Highlights: •Biofilms ennobled E corr of offshore construction alloys in natural seawater. •Filtration–UV irradiation delayed biofilm growth and activity on alloys. •Localized corrosion in seawater was lowered by the use of filtration–UV irradiation. •Biofilm community composition was affected by both substratum and seawater treatment. •Filtration–UV irradiation can be an ecofriendly practice for protection against MIC. -- Abstract: The effect of filtration–UV irradiation of seawater on the biofilm activity on several offshore structural alloys was evaluated in a continuous flow system over 90 days. Biofilms ennobled the electrode potential by +400 to 500 mV within a few days of exposure to raw untreated seawater. Filtration–UV irradiation of the seawater delayed the ennoblement of the steels for up to 40 days and lowered localized corrosion rates in susceptible alloys. Ennobling biofilms were composed of microbial cells, diatoms and extracellular polymeric substances and the bacterial community in biofilms was affected by both the alloy composition and seawater treatment

Effect of UV C irradiation on P53 in FADD+/+ and FADD-/- cells

International Nuclear Information System (INIS)

Matic, Igor; Radnic, Maja; Marijanovic, Inga; Furcic, Ivana; Nagy, Biserka

2008-01-01

The dominant paradigm of tumor biology is that evasion from apoptosis is one of the crucial features of malignant diseases and that the efficiency of cancer therapy depends on P53-dependent apoptosis. Because of the importance of apoptotic pathways in protecting cells against malignant transformation, disruption of apoptosis is extremely common in cancer cells, and is frequently due to mutations in the P53 tumor suppressor gene. Fas-associated death domain (FADD) is an adapter protein that is required for apoptosis induced by all known death receptors. FADD is implicated in death receptor-independent apoptotic response, such as DNA damage. We used embryonic fibroblasts derived from FADD knockout mice and their genetic counterparts. We predicted that UV exposure induces a loss of FADD function and leads to mutations in P53. Loss of FADD expression causes deregulation of apoptosis and expansion of mutated cells and initiation of cancer. We predicted that FADD dysfunction may be potentially advantageous for tumor growth and that FADD can act as a tumor suppressor. Cells were irradiated with UV C light (254 nm) using a germicidal lamp (Upland, CA). The culture media was drained before the irradiation and fresh media was added after. In the first experiment we irradiated cells with a dose of 25 J/m 2 and after 5 days we isolated genomic DNA but part of the cells were irradiated again with the same dose. After 5 days DNA were isolated so the cumulative irradiation dose was 50 J/m 2 . In the second experiment cells were irradiated ones with the dose of 40 J/m 2 and DNA was isolated after 18 days. Lethal dosage for each cell line is 50 J/m 2 . Genomic DNA was analyzed by allele-specific polymerase chain reaction (AS-PCR) for CC to TT mutation at codons 154-155 and 175-176 in exon 5 and for C to T mutations at codons 270 and 275 in exon 8 of the P53 gene. The mutant-specific forward primer was used for each mutation. The reverse primers for amplification of mutations were

Effects of solar and artificial UV irradiation on motility and phototaxis in the flagellate, Euglena gracilis

International Nuclear Information System (INIS)

Haeder, D.-P.

1986-01-01

The effect of solar irradiation on the percentage of motile cells, their average speed and their phototactic orientation to white actinic light was studied in the flagellate, Euglena gracilis. Unfiltered solar radiation in midsummer during mid-day at a location near Lisboa, Portugal, was found to impair motility within 2 h. This effect is exclusively due to the UV-B component of the radiation and not due to UV-A, visible light or a temperature increase. Likewise, phototactic orientation was drastically impaired. Reduction of the solar UV-B irradiation by insertion of an ozone-flooded plexiglass cuvette partially reduced the inhibition and covering the cuvettes with glass prevented any decrease in motility and photoorientation. Similar results were found with artificial irradiation (Xe lamps). After inoculation, the motility of the population follows an optimum curve (optimum at 8 days). Also, the UV-B effect on motility was smallest after about one week and increased for younger and older cultures. (author)

Modelling UV irradiances on arbitrarily oriented surfaces: effects of sky obstructions

OpenAIRE

Hess, M.; Koepke, P.

2008-01-01

A method is presented to calculate UV irradiances on inclined surfaces that additionally takes into account the influence of sky obstructions caused by obstacles such as mountains, houses, trees, or umbrellas. With this method it is thus possible to calculate the impact of UV radiation on biological systems, such as, for instance, the human skin or eye, in any natural or artificial environment. The method, which consists of a combination of radiation models, is explained here and the accuracy...

Local irradiation effects of one-dimensional ZnO based self-powered asymmetric Schottky barrier UV photodetector

Energy Technology Data Exchange (ETDEWEB)

Zhao, Yaxue [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Qi, Junjie, E-mail: junjieqi@ustb.edu.cn [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Biswas, Chandan [Department of Electrical Engineering, University of California Los Angeles, California 90095 (United States); Li, Feng; Zhang, Kui; Li, Xin [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Zhang, Yue, E-mail: yuezhang@ustb.edu.cn [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Key Laboratory of New Energy Materials and Technologies, University of Science and Technology Beijing, Beijing 100083 (China)

2015-09-15

A self-powered metal-semiconductor-metal (MSM) UV photodetector was successfully fabricated based on Ag/ZnO/Au structure with asymmetric Schottky barriers. This exhibits excellent performance compared to many previous studies. Very high photo-to-dark current ratio (approximately 10{sup 5}–10{sup 6}) was demonstrated without applying any external bias, and very fast switching time of less than 30 ms was observed during the investigation. Opposite photocurrent direction was generated by irradiating different Schottky diodes in the fabricated photodetector. Furthermore, the device performance was optimized by largely irradiating both the ZnO microwire (MW) junctions. Schottky barrier effect theory and O{sub 2} adsorption–desorption theories were used to investigate the phenomenon. The device has potential applications in self-powered UV detection field and can be used as electrical power source for electronic, optoelectronic and mechanical devices. - Highlights: • A self-powered Schottky barrier UV photodetector based on 1-D ZnO is fabricated. • For the first time we investigate the local irradiation effects of UV detector. • Irradiating both the junctions and ZnO can optimize the performance of the device.

Effect of UV irradiations on the structural and optical features of porous silicon: application in silicon solar cells

International Nuclear Information System (INIS)

Aouida, S.; Saadoun, M.; Boujmil, M.F.; Ben Rabha, M.; Bessaies, B.

2004-01-01

The aim of this paper is to investigate the structural and optical stability of porous silicon layers (PSLs) planned to be used in silicon solar cells technology. The PSLs were prepared by a HNO 3 /HF vapor etching (VE) based method. Fourier transform infrared (FT-IR) spectroscopy shows that fresh VE-based PSLs contain N-H and Si-F bonds related to a ammonium hexafluorosilicate (NH 4 ) 2 SiF 6 minor phase, and conventional Si-H x and Si-O x bonds. Free air exposures of PSLs without and with UV irradiation lead to oxidation or photo-oxidation of the porous layer, respectively. FT-IR characterisation of the PSLs shows that UV irradiations modify the transformation kinetics replacing instable Si-H x by Si-O x or Si-O-H bonds. When fresh PSLs undergo free air oxidation within 7 days, the surface reflectivity decreases from 10 to about 8%, while it drops to about 4% when a 10 min free air UV irradiation is applied. Long periods of free air oxidation do not ensure the reflectivity to be stable, whereas it becomes stable after only 10 min of UV irradiation. This behaviour was explained taking into account the kinetic differences between oxidation with and without UV irradiation. Fresh VE-based PSLs were found to improve efficiently the photovoltaic (PV) characteristics of crystalline silicon solar cells. The passivating action of VE-based PSLs was discussed. An improvement of the PV performances was observed solely for stable oxidized porous silicon (PS) structures obtained from UV irradiations

Artificial light pollution: Shifting spectral wavelengths to mitigate physiological and health consequences in a nocturnal marsupial mammal.

Science.gov (United States)

Dimovski, Alicia M; Robert, Kylie A

2018-05-02

The focus of sustainable lighting tends to be on reduced CO 2 emissions and cost savings, but not on the wider environmental effects. Ironically, the introduction of energy-efficient lighting, such as light emitting diodes (LEDs), may be having a great impact on the health of wildlife. These white LEDs are generated with a high content of short-wavelength 'blue' light. While light of any kind can suppress melatonin and the physiological processes it regulates, these short wavelengths are potent suppressors of melatonin. Here, we manipulated the spectral composition of LED lights and tested their capacity to mitigate the physiological and health consequences associated with their use. We experimentally investigated the impact of white LEDs (peak wavelength 448 nm; mean irradiance 2.87 W/m 2 ), long-wavelength shifted amber LEDs (peak wavelength 605 nm; mean irradiance 2.00 W/m 2 ), and no lighting (irradiance from sky glow light treatments. White LED exposed wallabies had significantly suppressed nocturnal melatonin compared to no light and amber LED exposed wallabies, while there was no difference in lipid peroxidation. Antioxidant capacity declined from baseline to week 10 under all treatments. These results provide further evidence that short-wavelength light at night is a potent suppressor of nocturnal melatonin. Importantly, we also illustrate that shifting the spectral output to longer wavelengths could mitigate these negative physiological impacts. © 2018 Wiley Periodicals, Inc.

Effect of UV-C irradiation on growth, sporulation and pathogenicity of cochliobolus sativus isolates

International Nuclear Information System (INIS)

Jawhar, M.; Arabi, M.I.E.

1999-12-01

More than 30 isolates of Cochliobolus sativus, the causal agent of common root rot disease; were collected from different regions of Syria. Seven of them were exposed to UV-C light for 40 or 60 h . at a dose rate of 2.52x10 -3 W/cm 2 . A significant increases in the mycelium growth and sporulation were detected (p<0.001). Within the studied range of UV wave length, these two parameters were increased upon increasing the period of exposure to UV-C light. The pathogenicity of four isolates was evaluated after 60 h. of UV irradiation. The response to UV irradiation varied among these isolates, and resulted in an increase in their virulence level (as assessed by evaluating disease severity on sub-crown internodes). Five barley genotypes possessing different levels of resistance to C. sativus were studied. Arabi Abiad was the most susceptible cultivar whereas, Taka 76 line was moderately susceptible. It is concluded that it is possible to implement the positive effect of low doses of UV-C in stimulating the sporulation of fungi, which are difficult to sporulate on artificial media. (author)

Effect of medium replenishment or composition on [3H] thymidine incorporation in uv-irradiated CHO-K1 cells

International Nuclear Information System (INIS)

Newman, C.N.; Miller, J.H.

1985-03-01

Because culture medium contains uv-absorbing material, it is usually removed just before uv-irradiation of tissue culture monolayers. However, medium removal and replenishment with fresh medium alone (sham-irradiation) causes up to a 10-fold reduction in the rate of [ 3 H]TdR incorporation in CHO-K1 cells which persists for several hours. This reduction, which is much smaller ( 3 H]TdR pulse-label in conditioned (spent) and in fresh medium; TdR in the former is converted by cells to thymine. When responses of uv-irradiated cells are normalized to responses of corresponding sham-irradiated cultures, considerable variation is observed in replicate experiments because fresh medium appears to induce transient metabolic imbalances in irradiated cells which are not readily controlled. This problem can, in part, be circumvented by replenishing treated cultures with the original spent medium; however, the presence of CdR in the growth medium still causes an anomalous 2-3-fold greater uv-induced reduction in [ 3 H]TdR incorporation than is observed in the absence of CdR. 17 refs., 3 figs., 1 tab

Chromosomal Integrity after UV Irradiation Requires FANCD2-Mediated Repair of Double Strand Breaks.

Science.gov (United States)

Federico, María Belén; Vallerga, María Belén; Radl, Analía; Paviolo, Natalia Soledad; Bocco, José Luis; Di Giorgio, Marina; Soria, Gastón; Gottifredi, Vanesa

2016-01-01

Fanconi Anemia (FA) is a rare autosomal recessive disorder characterized by hypersensitivity to inter-strand crosslinks (ICLs). FANCD2, a central factor of the FA pathway, is essential for the repair of double strand breaks (DSBs) generated during fork collapse at ICLs. While lesions different from ICLs can also trigger fork collapse, the contribution of FANCD2 to the resolution of replication-coupled DSBs generated independently from ICLs is unknown. Intriguingly, FANCD2 is readily activated after UV irradiation, a DNA-damaging agent that generates predominantly intra-strand crosslinks but not ICLs. Hence, UV irradiation is an ideal tool to explore the contribution of FANCD2 to the DNA damage response triggered by DNA lesions other than ICL repair. Here we show that, in contrast to ICL-causing agents, UV radiation compromises cell survival independently from FANCD2. In agreement, FANCD2 depletion does not increase the amount of DSBs generated during the replication of UV-damaged DNA and is dispensable for UV-induced checkpoint activation. Remarkably however, FANCD2 protects UV-dependent, replication-coupled DSBs from aberrant processing by non-homologous end joining, preventing the accumulation of micronuclei and chromatid aberrations including non-homologous chromatid exchanges. Hence, while dispensable for cell survival, FANCD2 selectively safeguards chromosomal stability after UV-triggered replication stress.

Pyrimidine dimer sites associated with the daughter DNA strands in uv-irradiated human fibroblasts

Energy Technology Data Exchange (ETDEWEB)

Lehmann, A R; Kirk-Bell, S [Sussex Univ., Brighton (UK)

1978-03-01

Pyrimidine dimer sites associated with the newly-synthesized DNA were detected during post-replication repair of DNA in uv-irradiated human fibroblasts. These pyrimidine dimer sites were inferred from a decrease in the molecular weight of pulse-labelled DNA after treatment with an extract of Micrococcus luteus containing uv-specific endonuclease activity. In DNA synthesized immediately after irradiation, the frequency of these daughter strand dimer sites was 7 to 20% of that in the parental DNA. Such sites were found in fibroblasts from normal donors and from xeroderma pigmentosum patients (with defects in excision-repair or post-replication repair). They were excised from the DNA of normal cells. As the time between uv irradiation and pulse-labelling was increased, the frequency of dimer sites associated with the labelled DNA decreased. If the pulse-label was delivered 6 h after irradiation of normal cells or excision-defective xeroderma pigmentosum cells, no dimer sites were detected in the labelled DNA. It has usually been assumed that daughter-strand dimer sites were the result of recombinational exchanges. The assay procedure used in these experiments and in similar experiments of others did not distinguish between labelled DNA containing pyrimidine dimers within the labelled section, and labelled DNA which did not contain pyrimidine dimers but was attached to unlabelled DNA which did contain dimers. The latter structures would arise during normal replication immediately following uv irradiation of mammalian cells. Calculations are presented which suggest that a significant proportion and conceivably all of the dimer sites associated with the daughter strands may have arisen in this way, rather than from recombinational exchanges as has been generally assumed.

Pyrimidine dimer sites associated with the daughter DNA strands in UV-irradiated human fibroblasts

International Nuclear Information System (INIS)

Lehmann, A.R.; Kirk-Bell, S.

1978-01-01

Pyrimidine dimer sites associated with the newly-synthesized DNA were detected during post-replication repair of DNA in UV-irradiated human fibroblasts. These pyrimidine dimer sites were inferred from a decrease in the molecular weight of pulse-labelled DNA after treatment with an extract of Micrococcus luteus containing UV-specific endonuclease activity. In DNA synthesized immediately after irradiation the frequency of these daughter strand dimer sites was 7-20% of that in the parental DNA. Such sites were found in fibroblasts from normal donors and from xeroderma pigmentosum patients (with defects in excision-repair or post-replication repair). They were excised from the DNA of normal cells. As the time between UV-irradiation and pulse-labelling was increased, the frequency of dimer sites associated with the labelled DNA decreased. If the pulse-label was delivered 6 h after irradiation of normal cells or excision-defective xeroderma pigmentosum cells, no dimer sites were detected in the labelled DNA. It has usually been assumed that daughter-strand dimer sites were the result of recombinational exchanges. The assay procedure used in these experiments and in similar experiments of others did not distinguish between labelled DNA containing pyrimidine dimers within the labelled section, and labelled DNA which did not contain pyrimidine dimers but was attached to unlabelled DNA which did contain dimers. The latter structures would arise during normal replication immediately following UV-irradiation of mammalian cells. Calculations are presented which suggest that a significant proportion and conceivably all of the dimer sites associated with the daughter strands may have arisen in this way, rather than from recombinational exchanges as has been generally assumed. (author)

Preparation and antibacterial activities of chitosan-gallic acid/polyvinyl alcohol blend film by LED-UV irradiation.

Science.gov (United States)

Yoon, Soon-Do; Kim, Young-Mog; Kim, Boo Il; Je, Jae-Young

2017-11-01

Active blend films from chitosan-gallic acid (CGA) and polyvinyl alcohol (PVA) were prepared via a simple mixing and casting method through the addition of citric acid as a plasticizer. The CGA/PVA blend films were characterized using Fourier transform infrared spectroscopy (FT-IR). The mechanical properties including tensile strength (TS) and elongation at break (%E), degree of solubility (S) and swelling behavior (DS), water vapor adsorption, and antimicrobial activities of the CGA/PVA blend films with and without LED (light emitting diode)-UV irradiation were also investigated. The CGA/PVA blend films exposed to UV irradiation exerted a higher TS (43.5MPa) and lower %E (50.40), S (0.38) and DS (2.73) compared to the CGA/PVA blend films (TS=41.7MPa, %E=55.40, S=0.42, and DS=3.16) not exposed LED-UV irradiation, indicating that the cross-linkage between CGA and PVA had been strengthened by LED-UV irradiation. However, the water vapor adsorption in the CGA/PVA blend films increased due to the changes of surface roughness and pore volume after LED-UV irradiation, and all values increased by increasing the CGA concentrations in the CGA/PVA blend films. The antimicrobial activities of the CGA/PVA blend films showed that the efficient concentration of CGA in the CGA/PVA blend films was over 1.0%. Taken together, the CGA/PVA blend films have potential for use as food packing materials. Copyright © 2017 Elsevier B.V. All rights reserved.

Sensitivity of two ecotypes of Arabidopsis Thaliana (Cvi and Te) towards UV-B irradiation

International Nuclear Information System (INIS)

Velichkova, M.; Stanoeva, D.; Popova, A.

2013-01-01

he susceptibility of Arabidopsis thaliana towards the detrimental effect of UV-B irradiation was investigated using two ecotypes, Cvi and Te. The effect of UV-B treatment on primary photosynthetic reactions - energy interaction between the main pigment-protein complexes and oxygen evolution, was evaluated at low (4 0 C) and at room (22 0 C) temperature. UV-B-induced alterations of investigated photosynthetic reactions are better expressed at 22 0 C than at 4 0 C for Cvi. For Te ecotype the energy interaction was suppressed to higher extent at 22 0 C, while oxygen evolving activity was affected similarly at both temperatures. At low and room temperature, the energy interaction in the complex PSII-core antenna is affected stronger by UV-B treatment than the energy distribution between both photosystems, as revealed by fluorescence ratios of 77 K spectra. The results presented indicate that the Arabidopsis thaliana ecotype Cvi (Cape Verde Islands) is less affected by UV-B irradiation in respect to the investigated primary photosynthetic reactions than the ecotype Te (Finland)

Topical Administration of Manuka Oil Prevents UV-B Irradiation-Induced Cutaneous Photoaging in Mice

Directory of Open Access Journals (Sweden)

Oh Sook Kwon

2013-01-01

Full Text Available Manuka tree is indigenous to New Zealand, and its essential oil has been used as a traditional medicine to treat wounds, fever, and pain. Although there is a growing interest in the use of manuka oil for antiaging skin care products, little is known about its bioactivity. Solar ultraviolet (UV radiation is the primary environmental factor causing skin damage and consequently premature aging. Therefore, we evaluated manuka oil for its effects against photoaging in UV-B-irradiated hairless mice. Topical application of manuka oil suppressed the UV-B-induced increase in skin thickness and wrinkle grading in a dose-dependent manner. Application of 10% manuka oil reduced the average length, depth, and % area of wrinkles significantly, and this was correlated with inhibition of loss of collagen fiber content and epidermal hyperplasia. Furthermore, we observed that manuka oil could suppress UV-B-induced skin inflammation by inhibiting the production of inflammatory cytokines. Taken together, this study provides evidence that manuka oil indeed possesses antiphotoaging activity, and this is associated with its inhibitory activity against skin inflammation induced by UV irradiation.

Impact of Dissolved Oxygen during UV-Irradiation on the Chemical Composition and Function of CHO Cell Culture Media.

Science.gov (United States)

Meunier, Sarah M; Todorovic, Biljana; Dare, Emma V; Begum, Afroza; Guillemette, Simon; Wenger, Andrew; Saxena, Priyanka; Campbell, J Larry; Sasges, Michael; Aucoin, Marc G

2016-01-01

Ultraviolet (UV) irradiation is advantageous as a sterilization technique in the biopharmaceutical industry since it is capable of targeting non-enveloped viruses that are typically challenging to destroy, as well as smaller viruses that can be difficult to remove via conventional separation techniques. In this work, we investigated the influence of oxygen in the media during UV irradiation and characterized the effect on chemical composition using NMR and LC-MS, as well as the ability of the irradiated media to support cell culture. Chemically defined Chinese hamster ovary cell growth media was irradiated at high fluences in a continuous-flow UV reactor. UV-irradiation caused the depletion of pyridoxamine, pyridoxine, pyruvate, riboflavin, tryptophan, and tyrosine; and accumulation of acetate, formate, kynurenine, lumichrome, and sarcosine. Pyridoxamine was the only compound to undergo complete degradation within the fluences considered; complete depletion of pyridoxamine was observed at 200 mJ/cm2. Although in both oxygen- and nitrogen-saturated media, the cell culture performance was affected at fluences above 200 mJ/cm2, there was less of an impact on cell culture performance in the nitrogen-saturated media. Based on these results, minimization of oxygen in cell culture media prior to UV treatment is recommended to minimize the negative impact on sensitive media.

Effect of UV-B irradiance on the ATP content of microorganisms of the Weddell Sea (Antartica)

Energy Technology Data Exchange (ETDEWEB)

Vosjan, J.H.; Nieuwland, G. (Netherlands Inst. for Sea Research, Den Burg (Netherlands)); Doehler, G. (Frankfurt Universitaet (Federal Republic of Germany). Botanisches Institut)

1990-06-01

The effect of UV-B irradiation on the ATP content of natural assemblages of planktonic microorganisms in the upper 30-m water layer of the Weddell Sea (Antartica) was studied. After five hours of irradiation with UV (290-320 nm) of 1.35 W.m{sup -2} a 75% decrease in the ATP content of the microorganisms was observed. (author). 11 refs.; 3 figs.

Protective effects of Mengshan green tea and hawk tea against UV-ray irradiation

International Nuclear Information System (INIS)

Chen Xiaoming; Ren Zhenglong; Zhang Huaiyu; Tang Zongxiang; Luo Peigao

2005-01-01

A group of cultured normal human skin-derived fibroblasts was used as the cell model to investigate protective and repair effects of aqueous extracts of Mengshan green tea and Hawk tea against 320-400 nm UV-ray irradiation, with the methods of MTT colorimetry and LDH release. It was found that the aqueous extracts had strong protective effect on fibroblasts against the UV-rays with dose dependence. There were no significant differences between the two kinds of tea aqueous extracts in a higher concentration of 5 mg/mL, whereas at lower concentrations of 2.5 and 1.25 mg/mL the, green tea aqueous extract was less effective than the hawk-tea aqueous extract in protecting fibroblasts from the UV-ray damage. Meanwhile, it was discovered that the green tea and hawk-tea aqueous extract could repair damages induced by the UV irradiation with dose dependence. But there were no statistically significant differences between the two kinds of aqueous extract. The effects may be related to antioxidant effect of tea polyphenol. (authors)

UV waveguides light fabricated in fluoropolymer CYTOP by femtosecond laser direct writing.

Science.gov (United States)

Hanada, Yasutaka; Sugioka, Koji; Midorikawa, Katsumi

2010-01-18

We have fabricated optical waveguides inside the UV-transparent polymer, CYTOP, by femtosecond laser direct writing for propagating UV light in biochip applications. Femtosecond laser irradiation is estimated to increase the refractive index of CYTOP by 1.7 x 10(-3) due to partial bond breaking in CYTOP. The waveguide in CYTOP has propagation losses of 0.49, 0.77, and 0.91 dB/cm at wavelengths of 632.8, 355, and 266 nm, respectively.

Comparative potency of different UV sources in reducing the density and antigen-presenting capacity of Langerhans cells in C3H mice

NARCIS (Netherlands)

Pierik, F.H.

1994-01-01

Although broadband UV.B irradiation has been shown to induce selective immunosuppression in a variety of experimental systems, the wavelength dependence of the immunornodulation and the initial events in the skin remain unclear. In the present study three UV lamps werc used at suberythermal doses on

Postreplicational formation and repair of DNA double-strand breaks in UV-irradiated Escherichia coli uvrB cells

International Nuclear Information System (INIS)

Wang, Tzuchien V.; Smith, K.C.

1986-01-01

The number of DNA double-strand breaks formed in UV-irradiated uvrB recF recB cells correlates with the number of unrepaired DNA daughter-strand gaps, and is dependent on DNA synthesis after UV-irradiation. These results are consistent with the model that the DNA double-strand breaks that are produced in UV-irradiated excision-deficient cells occur as the result of breaks in the parental DNA opposite unrepaired DNA daughter-strand gaps. By employing a temperature-sensitive recA200 mutation, we have devised an improved assay for studying the formation and repair of these DNA double-strand breaks. Possible mechanisms for the postreplication repair of DNA double-strand breaks are discussed. (Auth.)

The effects of UV irradiation and gas plasma treatment on living mammalian cells and bacteria: a comparative approach

NARCIS (Netherlands)

Sosnin, E.A.; Stoffels - Adamowicz, E.; Erofeev, M.V.; Kieft, I.E.; Kunts, S.E.

2004-01-01

Living mammalian cells and bacteria were exposed to irradiation from narrow-band UV lamps and treated with a nonthermal gas plasma (plasma needle). The model systems were: Chinese Hamster Ovary (CHO-K1) cells (fibroblasts) and Escherichia Coli bacteria. UV irradiation can lead to cell death

Comparison of UV irradiances from Aura/Ozone Monitoring Instrument (OMI) with Brewer measurements at El Arenosillo (Spain) - Part 2: Analysis of site aerosol influence

Science.gov (United States)

Cachorro, V. E.; Toledano, C.; Antón, M.; Berjón, A.; de Frutos, A.; Vilaplana, J. M.; Arola, A.; Krotkov, N. A.

2010-12-01

Several validation studies have shown a notable overestimation of the clear sky ultraviolet (UV) irradiance at the Earth's surface derived from satellite sensors such as the Total Ozone Mapping Spectrometer (TOMS) and the Ozone Monitoring Instrument (OMI) with respect to ground-based UV data at many locations. Most of this positive bias is attributed to boundary layer aerosol absorption that is not accounted for in the TOMS/OMI operational UV algorithm. Therefore, the main objective of this study is to analyse the aerosol effect on the bias between OMI erythemal UV irradiance (UVER) and spectral UV (305 nm, 310 nm and 324 nm) surface irradiances and ground-based Brewer spectroradiometer measurements from October 2004 to December 2008 at El Arenosillo station (37.1° N, 6.7° W, 20 m a.s.l.), with meteorological conditions representative of the South-West of Spain. The effects of other factors as clouds, ozone and the solar elevation over this intercomparison were analysed in detail in a companion paper (Antón et al., 2010). In that paper the aerosol effects were studied making only a rough evaluation based on aerosol optical depth (AOD) information at 440 nm wavelength (visible range) without applying any correction. We have used the precise information given by single scattering albedo (SSA) from AERONET for the determination of absorbing aerosols which has allowed the correction of the OMI UV data. An aerosol correction expression was applied to the OMI operational UV data using two approaches to estimate the UV absorption aerosol optical depth, AAOD. The first approach was based on an assumption of constant SSA value of 0.91. This approach reduces the OMI UVER bias against the reference Brewer data from 13.4% to 8.4%. Second approach uses daily AERONET SSA values reducing the bias only to 11.6%. Therefore we have obtained a 37% and 12% of improvement respectively. For the spectral irradiance at 324 nm, the OMI bias is reduced from 10.5% to 6.98% for constant

Effect of UV-B (302 nm) irradiation on isolated rat hepatocytes

International Nuclear Information System (INIS)

Lahiri, S.; Habibullah, C.M.; Ayesha, Q.; Khan, A.A.; Srinivas, V.K.; Naithani, R.

1995-01-01

The present study aimed to evaluate the effect of UV-B irradiation on the functional integrity, and the metabolic and detoxifying capacity of isolated rat hepatocytes. Isolated rat hepatocytes were irradiated in various doses (400 Jm -2 , 600 Jm -2 , 800 Jm -2 and 1000 Jm -2 ). The cells were assayed for total lactate dehydrogenase, Na + -K + -ATPase, ATPase, ornithine carbamyltransferase activity (OCT) and urea production capacity. Lactate dehydrogenase and Na + -K + -ATPase activity were significantly decreased in all four irradiated groups (P<0.001), whereas viability, OCT and urea production capacity showed no alterations. (au) 22 refs

Effects of UV-B irradiation on growth, survival, pigmentation and nitrogen metabolism enzymes in Cyanobacteria

Energy Technology Data Exchange (ETDEWEB)

Sinha, R.P.; Hader, D.P. [Institut fuer Botanik und Pharmazeutische Biologie, Friedrich-Alexander Universitaet, Erlangen (Germany); Kumar, H.D.; Kumar, A. [Banaras Hindu University, Varanasi (India)

1995-12-31

The effects of artificial UV-B irradiation on growth, survival, pigmentation, nitrate reductase (NR), glutamine synthetase (GS) and total protein profile have been studied in a number of N{sub 2}-fixing cyanobacterial strains isolated from rice (paddy) fields in India. Different organisms show different effects in terms of growth and survival. Complete killing of Anabaena sp. and Nostoc carmium occurs after 120 min of UV-B exposure, whereas the same occurs only after 150 min of exposure in the case of Nostoc commune and Scytonema sp. Growth patterns of the cells treated with UV-B revealed that Nostoc commune and Scytonema sp. are comparatively more tolerant than Anabaena sp. and Nostoc carmium. Pigment content, particularly phycocyanin, was severely decreased following UV-B irradiation in all strains tested so far. In vivo NR activity was found to increase, while in vivo GS activity was decreased following exposure to UV-B for different durations in all test organisms; although complete inhibition of GS activity did not occur even after 120 min of UV-B exposure. (author). 37 refs, 6 figs.

Effects of UV-B irradiation on growth, survival, pigmentation and nitrogen metabolism enzymes in Cyanobacteria

International Nuclear Information System (INIS)

Sinha, R.P.; Hader, D.P.; Kumar, H.D.; Kumar, A.

1995-01-01

The effects of artificial UV-B irradiation on growth, survival, pigmentation, nitrate reductase (NR), glutamine synthetase (GS) and total protein profile have been studied in a number of N 2 -fixing cyanobacterial strains isolated from rice (paddy) fields in India. Different organisms show different effects in terms of growth and survival. Complete killing of Anabaena sp. and Nostoc carmium occurs after 120 min of UV-B exposure, whereas the same occurs only after 150 min of exposure in the case of Nostoc commune and Scytonema sp. Growth patterns of the cells treated with UV-B revealed that Nostoc commune and Scytonema sp. are comparatively more tolerant than Anabaena sp. and Nostoc carmium. Pigment content, particularly phycocyanin, was severely decreased following UV-B irradiation in all strains tested so far. In vivo NR activity was found to increase, while in vivo GS activity was decreased following exposure to UV-B for different durations in all test organisms; although complete inhibition of GS activity did not occur even after 120 min of UV-B exposure. (author)

Investigation of concept of efficient short wavelength laser. Quarterly progress report, 1 August 1978--31 October 1978

International Nuclear Information System (INIS)

Piper, L.G.; Krech, R.H.; Pugh, E.R.; Taylor, R.L.

1978-01-01

A concept for the development of an efficient short wavelength laser based on a class of endoergic molecules-azides is being studied. One of these two laser-device experiments involves generating high concentrations of azide radicals in the thermal pyrolysis of solid, ionic azides, with the subsequent excitation of the N 2 (B 3 pi/sub g/) state from azide-radical recombination. Laser action would then take place upon the N 2 (B 3 pi/sub g/ - A 3 Sigma + /sub u/), first-postive transition. The second laser-demonstration experiment involves creating a high density of NCl(b 1 Sigma + ) state by uv photolysis of ClN 3 . In this case laser emission is expected on the NCl(b 1 Sigma + → X 3 Sigma - ) transition at 665 nm

COMPARATIVE ANALYSIS OF UV-C AND UV-B RADIATION INFLUENCE ON PLANT OBJECTS

Directory of Open Access Journals (Sweden)

О. Міхєєв

2011-04-01

Full Text Available General aim of work – comparative research of temporal regularities of growth processes of pea,that was grown under normal conditions and with application of UV-C and UV-B irradiation ofstem part, and also detection of irradiation dose relations to parameter of root and stem part sproutsgrowth rate of Aronis pea. Research subject of UV-C and UV-B irradiation influence on dynamicsof plant growth parameters in each set of experiments was alteration of growth rate, pecularities ofgrowth dynamics in different conditions of experiment, detection of UV-C and UV-B irradiationdoses range, that stimulate or inhibit growth parameters of pea sprouts. The investigation resulted indetermination 1,3 times higher efficiency of UV-V irradiation comparing to UV-B irradiation.Reaction of root didn’t depend on the type of UV-radiation

Operational characteristics of the OMEGA short-wavelength laser fusion facility

International Nuclear Information System (INIS)

Soures, J.M.; Hutchison, R.; Jacobs, S.; McCrory, R.L.; Peck, R.; Seka, W.

1984-01-01

Twelve beams of the OMEGA, 24 beam direct-drive laser facility have been converted to 351-nm wavelength operation. The performance characteristics of this short-wavelength facility will be discussed. Beam-to-beam energy balance of +-2.3% and on-target energy, at 351-nm, in excess of 70 J per beam have been demonstrated. Long-term performance (>600 shots) of the system has been optimized by appropriate choice of index matching liquid, optical materials and coatings. The application of this system in direct-drive laser fusion experiments will be discussed

Dependence of adhesion strength between GaN LEDs and sapphire substrate on power density of UV laser irradiation

Energy Technology Data Exchange (ETDEWEB)

Park, Junsu [Department of Nano-Manufacturing Technology, Korea Institute of Machinery and Materials, 156 Gajeongbuk-Ro, Yuseong-Gu, Daejeon 34103 (Korea, Republic of); Sin, Young-Gwan [Department of Nano-Mechatronics, Korea University of Science and Technology (UST), 217 Gajeong-Ro, Yuseong-Gu, Daejeon 34113 (Korea, Republic of); Kim, Jae-Hyun [Department of Nano-Mechanics, Korea Institute of Machinery and Materials, 156 Gajeongbuk-Ro, Yuseong-Gu, Daejeon 34103 (Korea, Republic of); Kim, Jaegu, E-mail: gugu99@kimm.re.kr [Department of Nano-Manufacturing Technology, Korea Institute of Machinery and Materials, 156 Gajeongbuk-Ro, Yuseong-Gu, Daejeon 34103 (Korea, Republic of)

2016-10-30

Highlights: • Fundamental relationship between laser irradiation and adhesion strength, between gallium-nitride light emitted diode and sapphire substrate, is proposed during selective laser lift-off. • Two competing mechanisms affect adhesion at the irradiated interface between the GaN LED and sapphire substrate. • Ga precipitation caused by thermal decomposition and roughened interface caused by thermal damage lead to the considerable difference of adhesion strength at the interface. - Abstract: Selective laser lift-off (SLLO) is an innovative technology used to manufacture and repair micro-light-emitting diode (LED) displays. In SLLO, laser is irradiated to selectively separate micro-LED devices from a transparent sapphire substrate. The light source used is an ultraviolet (UV) laser with a wavelength of 266 nm, pulse duration of 20 ns, and repetition rate of 30 kHz. Controlled adhesion between a LED and the substrate is key for a SLLO process with high yield and reliability. This study examined the fundamental relationship between adhesion and laser irradiation. Two competing mechanisms affect adhesion at the irradiated interface between the GaN LED and sapphire substrate: Ga precipitation caused by the thermal decomposition of GaN and roughened interface caused by thermal damage on the sapphire. The competition between these two mechanisms leads to a non-trivial SLLO condition that needs optimization. This study helps understand the SLLO process, and accelerate the development of a process for manufacturing micro-LED displays via SLLO for future applications.

Effect of UV irradiation on cutaneous cicatrices: a randomized, controlled trial with clinical, skin reflectance, histological, immunohistochemical and biochemical evaluations.

Science.gov (United States)

Due, Eva; Rossen, Kristian; Sorensen, Lars Tue; Kliem, Anette; Karlsmark, Tonny; Haedersdal, Merete

2007-01-01

The aim of this study was to examine the effect of ultraviolet (UV) irradiation on human cutaneous cicatrices. In this randomized, controlled study, dermal punch biopsy wounds served as a wound healing model. Wounds healed by primary or second intention and were randomized to postoperative solar UV irradiation or to no UV exposure. Evaluations after 5 and 12 weeks included blinded clinical assessments, skin reflectance measurements, histology, immunohistochemistry, and biochemical analyses of the N-terminal propeptide from procollagen-1, hydroxyproline, hydroxylysine, and proline. Twelve weeks postoperatively, UV-irradiated cicatrices healing by second intention: (i) were significantly pointed out as the most disfiguring; (ii) obtained significantly higher scores of colour, infiltration and cicatrix area; and (iii) showed significantly higher increase in skin-reflectance measurements of skin-pigmentation vs. non-irradiated cicatrices. No histological, immunohistochemical or biochemical differences were found. In conclusion, postoperative UV exposure aggravates the clinical appearance of cicatrices in humans.

An apparatus for cattle-blood irradiation

International Nuclear Information System (INIS)

Damdinsuerehn, S.; Gunaadzav, T.; Chueltehm, D.; Sajnkhueue, Zh.; Byambaa, S.; Moenkhtsehtsehg, N.; Dorzhnyambuu, B.

1989-01-01

An apparatus for cattle-blood irradiation in vitro by low intensity ultraviolet light (10-12 w/m 2 ) emitted by mercury-quartz lamp at the wavelength range of 254-280 nm has been constructed. For this purpose a simple connection circuit for shunting the source electrodes by effective resistance and switching on electrical network in series through capacitor is presented. Stabilized cattle blood for UV-irradiation is running through 5mm diameter quartz tubes at the distance of 15mm from UV-lamp. Irradiated in this way blood sample is administered intravenously or intramuscular in various way. Method of using this source in veterinary practice is developed. Results of the use of this method during the last 4-5 years demonstrate the efficiency of treating and preventing from desease could be above 80%. 1 fig. (B.Sh.)

Induction of transcription from the long terminal repeat of Moloney murine sarcoma provirus by UV-irradiation, x-irradiation, and phorbol ester

International Nuclear Information System (INIS)

Lin, C.S.; Goldthwait, D.A.; Samols, D.

1990-01-01

The long terminal repeat (LTR) of Moloney murine sarcoma virus (Mo-MuSV) was used as a model system to study the stress response of mammalian cells to physical carcinogens. The chloramphenicol acetyltransferase (CAT) gene was inserted between two Mo-MuSV LTRs, and the LTR-CAT-LTR construct was used for virus production and was integrated into the genome of NIH 3T3 cells in the proviral form. This construct was used to assure that the integrated CAT gene was driven by the promoter of the LTR. Expression of the CAT gene was stimulated 4-fold by UV irradiation, and the peak of activity was observed at 18 hr. In contrast, stimulation of the CAT expression after x-irradiation was 2-fold and occurred at 6 hr. Phorbol myristate acetate also stimulated CAT activity 4-fold with a peak at 6 hr. Down-regulation of protein kinase C blocked totally the response to x-irradiation but only partially the response to UV. The protein kinase inhibitor H7 blocked the response to treatment by UV, x-ray, and phorbol ester

Variability of the nucleoli number in the progenies of intact and UV-irradiated clonogenic Hela cells

Energy Technology Data Exchange (ETDEWEB)

Kucheryavaya, N.A.; Zavol' naya, E.S.; Vakhtin, Yu.B. (AN SSSR, Leningrad. Inst. Tsitologii)

1981-01-01

The coefficient of the ''nucleoli number'' character heritability (h/sup 2/) in the population of intact Hela cells equals 0.21 to 0.33. UV-irradiation enhances almost equally both the intraclonic and population variability of the nucleoli number and, as a result, the coefficient of the ''nucleoli number'' character heritability does not change in the population of UV-irradiated Hela cells.

Chlorophyll bleaching by UV-irradiation in vitro and in situ: Absorption and fluorescence studies

International Nuclear Information System (INIS)

Zvezdanovic, Jelena; Cvetic, Tijana; Veljovic-Jovanovic, Sonja; Markovic, Dejan

2009-01-01

Chlorophyll bleaching by UV-irradiation has been studied by absorbance and fluorescence spectroscopy in extracts containing mixtures of photosynthetic pigments, in acetone and n-hexane solutions, and in aqueous thylakoid suspensions. Chlorophyll undergoes destruction (bleaching) accompanied by fluorescent transient formation obeying first-order kinetics. The bleaching is governed by UV-photon energy input, as well as by different chlorophyll molecular organizations in solvents of different polarities (in vitro), and in thylakoids (in situ). UV-C-induced bleaching of chlorophylls in thylakoids is probably caused by different mechanisms compared to UV-A- and UV-B-induced bleaching

Amarginal contribution of selected carotenoids to the supression of UV-irradiation-induced lecithin peroxidation in hexane solution

Directory of Open Access Journals (Sweden)

DRAGAN CVETKOVIC

2007-03-01

Full Text Available The aim of this work was to study the anticipated antioxidant role of four selected carotenoids in mixtures with lecithin lipoidal compounds in hexane solution, under continuous UV-irradiation in three different ranges (UV-A, UV-B and UV-C. Two carotenes (b-carotene and licopene and two xantophylls (lutein and neoxanthin were employed to control the lipid peroxidation process generated by UV-irradiation, by scavenging the involved free radicals. The results show that while carotenoids undergo a substantial, structural dependent destruction (bleaching, which is highly dependent on energy of the UV-photons, their contribution to the expected suppression of lecithin peroxidation is of marginal importance, not exceeding a maximum of 20%. The marginal antioxidant behaviour has been attributed to a highly unordered hexane solution, where the scavenging action of the carotenoids becomes less competitive.

The mechanism of untargeted mutagenesis in UV-irradiated yeast.

Science.gov (United States)

Lawrence, C W; Christensen, R B

1982-01-01

The SOS error-prone repair hypothesis proposes that untargeted and targeted mutations in E. coli both result from the inhibition of polymerase functions that normally maintain fidelity, and that this is a necessary precondition for translesion synthesis. Using mating experiments with excision deficient strains of Bakers' yeast, Saccharomyces cerevisiae, we find that up to 40% of cycl-91 revertants induced by UV are untargeted, showing that a reduction in fidelity is also found in irradiated cells of this organism. We are, however, unable to detect the induction or activation of any diffusible factor capable of inhibiting fidelity, and therefore suggest that untargeted and targeted mutations are the consequence of largely different processes. We propose that these observations are best explained in terms of a limited fidelity model. Untargeted mutations are thought to result from the limited capacity of processes which normally maintain fidelity, which are active during replication on both irradiated and unirradiated templates. Even moderate UV fluences saturate this capacity, leading to competition for the limited resource. Targeted mutations are believed to result from the limited, though far from negligible, capacity of lesions like pyrimidine dimers to form Watson-Crick base pairs.

The mechanism of untargeted mutagenesis in UV-irradiated yeast

International Nuclear Information System (INIS)

Lawrence, C.W.; Christensen, R.B.

1982-01-01

The SOS error-prone repair hypothesis proposes that untargeted and targeted mutations in E. coli both result from the inhibition of polymerase functions that normally maintain fidelity, and that this is a necessary precondition for translesion synthesis. Using mating experiments with excision deficient strains of Bakers' yeast, Saccharomyces cerevisiae, we find that up to 40% of cycl-91 revertants induced by UV are untargeted, showing that a reduction in fidelity is also found in irradiated cells of this organism. We are, however, unable to detect the induction or activation of any diffusible factor capable of inhibiting fidelity, and therefore suggest that untargeted and targeted mutations are the consequence of largely different processes. We propose that these observations are best explained in terms of a limited fidelity model. Untargeted mutations are thought to result from the limited capacity of processes which normally maintain fidelity, which are active during replication on both irradiated and unirradiated templates. Even moderate UV fluences saturate this capacity, leading to competition for the limited resource. Targeted mutations are believed to result from the limited, though far from negligible, capacity of lesions like pyrimidine dimers to form Watson-Crick base pairs. (orig.)

Short-Wavelength Light Enhances Cortisol Awakening Response in Sleep-Restricted Adolescents

Directory of Open Access Journals (Sweden)

Mariana G. Figueiro

2012-01-01

Full Text Available Levels of cortisol, a hormone produced by the adrenal gland, follow a daily, 24-hour rhythm with concentrations reaching a minimum in the evening and a peak near rising time. In addition, cortisol levels exhibit a sharp peak in concentration within the first hour after waking; this is known as the cortisol awakening response (CAR. The present study is a secondary analysis of a larger study investigating the impact of short-wavelength (λmax≈470 nm light on CAR in adolescents who were sleep restricted. The study ran over the course of three overnight sessions, at least one week apart. The experimental sessions differed in terms of the light exposure scenarios experienced during the evening prior to sleeping in the laboratory and during the morning after waking from a 4.5-hour sleep opportunity. Eighteen adolescents aged 12–17 years were exposed to dim light or to 40 lux (0.401 W/m2 of 470-nm peaking light for 80 minutes after awakening. Saliva samples were collected every 20 minutes to assess CAR. Exposure to short-wavelength light in the morning significantly enhanced CAR compared to dim light. Morning exposure to short-wavelength light may be a simple, yet practical way to better prepare adolescents for an active day.

Activation of eggs of the frog, Rana nigromaculata Hallowell, after localized UV-irradiation

International Nuclear Information System (INIS)

Sambuichi, Hajime

1981-01-01

To analyze the mode of transmission of the activating stimulus, the change in time course of the 2nd maturation division was examined in eggs of the frog, Rana nigromaculata, which were activated by insemination or by pricking after UV-irradiation at either the animal or the vegetal hemisphere. Irradiation of the animal (UAF) or the vegetal (UVF) hemisphere before insemination retarded the 2nd maturation division in comparison with that in normally fertilized eggs (CF). When the eggs were pricked at the irradiated surface (UAP and UVP, respectively), however, the 2nd maturation division progressed faster than that of CF. The comparison of the velocity of the 2nd maturation division between UAF and UVF, and also between UAP and UVP, showed that the cortical reaction in the vegetal hemisphere was affected by UV-irradiation more severely than that in the animal hemisphere. The results suggested that the quality of the granules or the constituent within the egg cortex might vary according to the regional difference in the egg surface. (author)

Chromosomal Integrity after UV Irradiation Requires FANCD2-Mediated Repair of Double Strand Breaks.

Directory of Open Access Journals (Sweden)

María Belén Federico

2016-01-01

Full Text Available Fanconi Anemia (FA is a rare autosomal recessive disorder characterized by hypersensitivity to inter-strand crosslinks (ICLs. FANCD2, a central factor of the FA pathway, is essential for the repair of double strand breaks (DSBs generated during fork collapse at ICLs. While lesions different from ICLs can also trigger fork collapse, the contribution of FANCD2 to the resolution of replication-coupled DSBs generated independently from ICLs is unknown. Intriguingly, FANCD2 is readily activated after UV irradiation, a DNA-damaging agent that generates predominantly intra-strand crosslinks but not ICLs. Hence, UV irradiation is an ideal tool to explore the contribution of FANCD2 to the DNA damage response triggered by DNA lesions other than ICL repair. Here we show that, in contrast to ICL-causing agents, UV radiation compromises cell survival independently from FANCD2. In agreement, FANCD2 depletion does not increase the amount of DSBs generated during the replication of UV-damaged DNA and is dispensable for UV-induced checkpoint activation. Remarkably however, FANCD2 protects UV-dependent, replication-coupled DSBs from aberrant processing by non-homologous end joining, preventing the accumulation of micronuclei and chromatid aberrations including non-homologous chromatid exchanges. Hence, while dispensable for cell survival, FANCD2 selectively safeguards chromosomal stability after UV-triggered replication stress.

Structural Evolution of Human Recombinant alfaB-Crystallin under UV Irradiation

DEFF Research Database (Denmark)

Sugiyama, Masaaki; Fujii, Noriko; Morimoto, Yukio

2008-01-01

External stresses cause certain proteins to lose their regular structure and aggregate. In order to clarify this abnormal aggregation process, a structural evolution of human recombinant aB-crystallin under UV irradiation was observed with in situ small-angle neutron scattering. The abnormal...

Short wavelength limits of current shot noise suppression

International Nuclear Information System (INIS)

Nause, Ariel; Dyunin, Egor; Gover, Avraham

2014-01-01

Shot noise in electron beam was assumed to be one of the features beyond control of accelerator physics. Current results attained in experiments at Accelerator Test Facility in Brookhaven and Linac Coherent Light Source in Stanford suggest that the control of the shot noise in electron beam (and therefore of spontaneous radiation and Self Amplified Spontaneous Emission of Free Electron Lasers) is feasible at least in the visible range of the spectrum. Here, we present a general linear formulation for collective micro-dynamics of e-beam noise and its control. Specifically, we compare two schemes for current noise suppression: a quarter plasma wavelength drift section and a combined drift/dispersive (transverse magnetic field) section. We examine and compare their limits of applicability at short wavelengths via considerations of electron phase-spread and the related Landau damping effect

Short wavelength limits of current shot noise suppression

Energy Technology Data Exchange (ETDEWEB)

Nause, Ariel, E-mail: arielnau@post.tau.ac.il [Faculty of Exact Sciences, Department of Physics, Tel Aviv University, Tel Aviv (Israel); Dyunin, Egor; Gover, Avraham [Faculty of Engineering, Department of Physical Electronics, Tel Aviv University, Tel Aviv (Israel)

2014-08-15

Shot noise in electron beam was assumed to be one of the features beyond control of accelerator physics. Current results attained in experiments at Accelerator Test Facility in Brookhaven and Linac Coherent Light Source in Stanford suggest that the control of the shot noise in electron beam (and therefore of spontaneous radiation and Self Amplified Spontaneous Emission of Free Electron Lasers) is feasible at least in the visible range of the spectrum. Here, we present a general linear formulation for collective micro-dynamics of e-beam noise and its control. Specifically, we compare two schemes for current noise suppression: a quarter plasma wavelength drift section and a combined drift/dispersive (transverse magnetic field) section. We examine and compare their limits of applicability at short wavelengths via considerations of electron phase-spread and the related Landau damping effect.

Assessing Ultraviolet Hazards Using Portable Measuring Instruments

Energy Technology Data Exchange (ETDEWEB)

Ridyard, A

2000-07-01

The 'Erythemal Action Spectrum' shows an increase of 10{sup 3} in human skin sensitivity to UV radiation over only 30 nm of change of wavelength, from 328 nm to 298 nm. This represents a severe challenge to the manufacturing and calibration of a portable instrument which can measure the vanishingly small amounts of short wavelength UV from solarium tanning lamps, and to apply accurately an action spectra to be able to quantify the hazard presented by such lamps to skin. The classification of UV lamp types from their 'effective irradiance' requires very sharp discrimination between UV power contained in the short wavelength and the long wavelength parts of the UV spectra, so radiometers give misleading results. The only instrument suitable for making these measurements is the spectroradiometer. The development of such an instrument in a hand held portable form is described, with the difficulties associated with its calibration and such factors as stray light rejection. (author)

Assessing Ultraviolet Hazards Using Portable Measuring Instruments

International Nuclear Information System (INIS)

Ridyard, A.

2000-01-01

The 'Erythemal Action Spectrum' shows an increase of 10 3 in human skin sensitivity to UV radiation over only 30 nm of change of wavelength, from 328 nm to 298 nm. This represents a severe challenge to the manufacturing and calibration of a portable instrument which can measure the vanishingly small amounts of short wavelength UV from solarium tanning lamps, and to apply accurately an action spectra to be able to quantify the hazard presented by such lamps to skin. The classification of UV lamp types from their 'effective irradiance' requires very sharp discrimination between UV power contained in the short wavelength and the long wavelength parts of the UV spectra, so radiometers give misleading results. The only instrument suitable for making these measurements is the spectroradiometer. The development of such an instrument in a hand held portable form is described, with the difficulties associated with its calibration and such factors as stray light rejection. (author)

Study of maleic anhydride and styrene grafted onto polypropylene induced by UV irradiation

International Nuclear Information System (INIS)

Li Zhenzhong; He Wei; Guo Hongjun; Zhang Wenxiong; Ma Yalin

2007-01-01

Maleic anhydride (MAH) and styrene (St) grafted onto polypropylene (PP) were prepared by UV irradiation. Effects of the irradiation time, monomer and initiator content on the grafting rate and melt flow rate (MFR) were studied. The results show that the optimal duration of UV irradiation is 30s. The grafting rate increases with initiator content when initiator content less than 0.6 phr, the MFR value of grafted PP reaches the highest point when benzophenone (BP) content is 0.4 phr. The content of MAH and St have an effect on the grafting rate and MFR value of the grafted PP, and the optimal contents of monomer is 4 phr. The existence of St as a comonomer reduces apparently the MFR value of grafted PP greatly. Grafted PP present significant changes in crystallization and fusion peaks, indicating differences in crystal size and formation after grafting reaction. (authors)