No evidence for UV-based nest-site selection in sticklebacks

Directory of Open Access Journals (Sweden)

Bakker Theo CM

2006-11-01

Full Text Available Abstract Background Nests are built in various animal taxa including fish. In systems with exclusive male parental care, the choice of a nest site may be an important component of male fitness. The nest site may influence male attractiveness as a mate, and male, embryo, and juvenile survival probabilities. Reproductively active three-spined stickleback males establish and defend a territory in which they build a nest. Territories can differ remarkably in qualities that influence male and female reproductive success like predation risk or abiotic factors such as dissolved oxygen concentration or lighting conditions. The latter may be important because in sticklebacks the extended visual capability into the ultraviolet (UV wave range plays a role in female mate choice. Males are thus expected to be choosy about the habitat in which they will build their nest. Results We tested nest-site choice in male three-spined sticklebacks with respect to different UV lighting conditions. Reproductively active males were given the simultaneous choice to build their nest either in an UV-rich (UV+ or an UV-lacking (UV- environment. Males exhibited no significant nest-site preferences with respect to UV+ or UV-. However, larger males and also heavier ones completed their nests earlier. Conclusion We found that UV radiation as well as differences in luminance had no influence on nest-site choice in three-spined sticklebacks. Males that built in the UV-rich environment were not different in any trait (body traits and UV reflection traits from males that built in the UV-poor environment. There was a significant effect of standard length and body mass on the time elapsed until nest completion in the UV experiment. The larger and heavier a male, the faster he completed his nest. In the brightness control experiment there was a significant effect only of body mass on the duration of nest completion. Whether nest building preferences with respect to UV lighting

The Surface UV Environment on Planets Orbiting M Dwarfs: Implications for Prebiotic Chemistry and the Need for Experimental Follow-up

Energy Technology Data Exchange (ETDEWEB)

Ranjan, Sukrit; Sasselov, Dimitar D. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Wordsworth, Robin, E-mail: sranjan@cfa.harvard.edu [Harvard Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02140 (United States)

2017-07-10

Potentially habitable planets orbiting M dwarfs are of intense astrobiological interest because they are the only rocky worlds accessible to biosignature search over the next 10+ years because of a confluence of observational effects. Simultaneously, recent experimental and theoretical work suggests that UV light may have played a key role in the origin of life on Earth, especially the origin of RNA. Characterizing the UV environment on M-dwarf planets is important for understanding whether life as we know it could emerge on such worlds. In this work, we couple radiative transfer models to observed M-dwarf spectra to determine the UV environment on prebiotic Earth-analog planets orbiting M dwarfs. We calculate dose rates to quantify the impact of different host stars on prebiotically important photoprocesses. We find that M-dwarf planets have access to 100–1000 times less bioactive UV fluence than the young Earth. It is unclear whether UV-sensitive prebiotic chemistry that may have been important to abiogenesis, such as the only known prebiotically plausible pathways for pyrimidine ribonucleotide synthesis, could function on M-dwarf planets. This uncertainty affects objects like the recently discovered habitable-zone planets orbiting Proxima Centauri, TRAPPIST-1, and LHS 1140. Laboratory studies of the sensitivity of putative prebiotic pathways to irradiation level are required to resolve this uncertainty. If steady-state M-dwarf UV output is insufficient to power these pathways, transient elevated UV irradiation due to flares may suffice; laboratory studies can constrain this possibility as well.

The Surface UV Environment on Planets Orbiting M Dwarfs: Implications for Prebiotic Chemistry and the Need for Experimental Follow-up

Science.gov (United States)

Ranjan, Sukrit; Wordsworth, Robin; Sasselov, Dimitar D.

2017-07-01

Potentially habitable planets orbiting M dwarfs are of intense astrobiological interest because they are the only rocky worlds accessible to biosignature search over the next 10+ years because of a confluence of observational effects. Simultaneously, recent experimental and theoretical work suggests that UV light may have played a key role in the origin of life on Earth, especially the origin of RNA. Characterizing the UV environment on M-dwarf planets is important for understanding whether life as we know it could emerge on such worlds. In this work, we couple radiative transfer models to observed M-dwarf spectra to determine the UV environment on prebiotic Earth-analog planets orbiting M dwarfs. We calculate dose rates to quantify the impact of different host stars on prebiotically important photoprocesses. We find that M-dwarf planets have access to 100–1000 times less bioactive UV fluence than the young Earth. It is unclear whether UV-sensitive prebiotic chemistry that may have been important to abiogenesis, such as the only known prebiotically plausible pathways for pyrimidine ribonucleotide synthesis, could function on M-dwarf planets. This uncertainty affects objects like the recently discovered habitable-zone planets orbiting Proxima Centauri, TRAPPIST-1, and LHS 1140. Laboratory studies of the sensitivity of putative prebiotic pathways to irradiation level are required to resolve this uncertainty. If steady-state M-dwarf UV output is insufficient to power these pathways, transient elevated UV irradiation due to flares may suffice; laboratory studies can constrain this possibility as well.

The Surface UV Environment on Planets Orbiting M Dwarfs: Implications for Prebiotic Chemistry and the Need for Experimental Follow-up

International Nuclear Information System (INIS)

Ranjan, Sukrit; Sasselov, Dimitar D.; Wordsworth, Robin

2017-01-01

Potentially habitable planets orbiting M dwarfs are of intense astrobiological interest because they are the only rocky worlds accessible to biosignature search over the next 10+ years because of a confluence of observational effects. Simultaneously, recent experimental and theoretical work suggests that UV light may have played a key role in the origin of life on Earth, especially the origin of RNA. Characterizing the UV environment on M-dwarf planets is important for understanding whether life as we know it could emerge on such worlds. In this work, we couple radiative transfer models to observed M-dwarf spectra to determine the UV environment on prebiotic Earth-analog planets orbiting M dwarfs. We calculate dose rates to quantify the impact of different host stars on prebiotically important photoprocesses. We find that M-dwarf planets have access to 100–1000 times less bioactive UV fluence than the young Earth. It is unclear whether UV-sensitive prebiotic chemistry that may have been important to abiogenesis, such as the only known prebiotically plausible pathways for pyrimidine ribonucleotide synthesis, could function on M-dwarf planets. This uncertainty affects objects like the recently discovered habitable-zone planets orbiting Proxima Centauri, TRAPPIST-1, and LHS 1140. Laboratory studies of the sensitivity of putative prebiotic pathways to irradiation level are required to resolve this uncertainty. If steady-state M-dwarf UV output is insufficient to power these pathways, transient elevated UV irradiation due to flares may suffice; laboratory studies can constrain this possibility as well.

Degradation of Solar Array Components in a Combined UV/VUV High Temperature Test Environment

Directory of Open Access Journals (Sweden)

Nömayr Christel

2017-01-01

A design verification test under UV/VUV conditions of sun exposed materials and technologies on component level is presented which forms part of the overall verification and qualification of the solar array design of the MTM and MPO. The test concentrates on the self-contamination aspects and the resulting performance losses of the solar array under high intensity and elevated temperature environment representative for the photovoltaic assembly (PVA.

Transcriptional and cellular effects of benzotriazole UV stabilizers UV-234 and UV-328 in the freshwater invertebrates Chlamydomonas reinhardtii and Daphnia magna.

Science.gov (United States)

Giraudo, Maeva; Cottin, Guillaume; Esperanza, Marta; Gagnon, Pierre; Silva, Amila O De; Houde, Magali

2017-12-01

Benzotriazole ultra violet stabilizers (BZT-UVs) are compounds used in many applications and products to prevent photochemical degradation. Despite their widespread presence in aquatic ecosystems and persistence in the environment, there are very limited data on their effects and toxicity, and their modes of action remain largely unknown. The objectives of the present study were to evaluate the chronic effects of 2 BZT-UVs, 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (UV-234) and 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (UV-328), on the freshwater green algae Chlamydomonas reinhardtii and the freshwater crustacean Daphnia magna. Organisms were exposed to 0.01 and 10 μg/L of UV-234, UV-328, as well as a mixture of the 2 compounds. Life-history endpoints (viability, reproduction, and growth) and oxidative stress-related biomarkers (gene transcription, reactive oxygen species [ROS] production, and lipid peroxidation) were measured. Daphnia magna growth, reproduction, and gene transcription were not impacted by 21-d individual or mixed exposure. After 96-h of exposure, no differences were observed on the cellular viability of C. reinhardtii for either of the 2 BZT-UVs. In the algae, results showed increased ROS production in response to UV-328 and lipid peroxidation following exposure to UV-234. Synergistic effects of the 2 BZT-UVs were evident at the transcriptional level with 2 to 6 times up-regulation of glutathione peroxidase (gp x ) in response to the mixture for all treatment conditions. The transcription of superoxide dismutase (sod), catalase (cat), and ascorbic peroxidase (apx) was also regulated by UV-234 and UV-328 in the green algae, most likely as a result of ROS production and lipid peroxidation. Results from the present study suggest potential impacts of UV-234 and UV-328 exposure on the antioxidant defense system in C. reinhardtii. Environ Toxicol Chem 2017;36:3333-3342. © 2017 Crown in the Right of Canada. Published by

Juno-UVS observation of the Io footprint: Influence of Io's local environment and passage into eclipse on the strength of the interaction

Science.gov (United States)

Hue, V.; Gladstone, R.; Greathouse, T. K.; Versteeg, M.; Bonfond, B.; Saur, J.; Davis, M. W.; Roth, L.; Grodent, D. C.; Gerard, J. C. M. C.; Kammer, J.; Bolton, S. J.; Levin, S.; Connerney, J. E. P.

2017-12-01

The Juno mission offers an unprecedented opportunity to study Jupiter, from its internal structure to its magnetospheric environment. Juno-UVS is a UV spectrograph with a bandpass of 70vantage point above the poles. In particular, UVS has observed the instantaneous Io footprint and extended tail as Io enters into eclipse. This observation may better constrain whether the atmosphere of Io is sustained via volcanic activity or sublimation. Among other processes, the modulation of Io's footprint brightness correlates to the strength of the interaction between the Io plasma torus and its ionosphere, which, in turn, is likely to be affected by the atmospheric collapse. UVS observed the Io footprint during two eclipses that occurred on PJ1 and PJ3, and one additional eclipse observation is planned during PJ9 (24 Oct. 2017). We present how the electrodynamic coupling between Io and Jupiter is influenced by changes in Io's local environment, e.g. Io's passage in and out of eclipse and Io's traverse of the magnetodisc plasma sheet.

Polyurethane acrylate networks including cellulose nanocrystals: a comparison between UV and EB- curing

International Nuclear Information System (INIS)

Furtak-Wrona, K.; Kozik-Ostrówka, P.; Jadwiszczak, K.; Maigret, J.E.; Aguié-Béghin, V.; Coqueret, X.

2018-01-01

A water-based polyurethane (PUR) acrylate water emulsion was selected as a radiation curable matrix for preparing nanocomposites including cellulose nanocrystals (CNC) prepared by controlled hydrolysis of Ramie fibers. Cross-linking polymerization of samples prepared in the form of films or of 1 mm-thick bars was either initiated by exposure to the 395 nm light of a high intensity LED lamp or by treatment with low energy electron beam (EB). The conversion level of acrylate functions in samples submitted to increasing radiation doses was monitored by Fourier Transform Infrared Spectroscopy (FTIR). Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA) were used to characterize changes in the glass transition temperature of the PUR-CNC nanocomposites as a function of acrylate conversion and of CNC content. Micromechanical testing indicates the positive effect of 1 wt% CNC on Young's modulus and on the tensile strength at break (σ) of cured nanocomposites. The presence of CNC in the PUR acrylate matrix was shown to double the σ value of the nanocomposite cured to an acrylate conversion level of 85% by treatment with a 25 kGy dose under EB, whereas no increase of σ was observed in UV-cured samples exhibiting the same acrylate conversion level. The occurrence of grafting reactions inducing covalent linkages between the polysaccharide nanofiller and the PUR acrylate matrix during the EB treatment is advanced as an explanation to account for the improvement observed in samples cured under ionizing radiation. - Highlights: • Nanocomposites were prepared from o/w PUR acrylate emulsion and CNC suspension. • Nanocomposite and reference materials were cured to the same conversion by UV or EB. • Introducing 1 wt% CNC in EB-cured composites doubles the tensile strength. • UV-cured nanocomposites did not show significant improvement in tensile strength.

Higher plants and UV-B radiation: balancing damage, repair and acclimation

International Nuclear Information System (INIS)

Jansen, M.A.K.; Gaba, V.; Greenberg, B.M.

1998-01-01

Although UV-B is a minor component of sunlight, it has a disproportionately damaging effect on higher plants. Ultraviolet-sensitive targets include DNA, proteins and membranes, and these must be protected for normal growth and development. DNA repair and secondary metabolite accumulation during exposure to UV-B have been characterized in considerable detail, but little is known about the recovery of photosynthesis, induction of free-radical scavenging and morphogenic changes. A future challenge is to elucidate how UV-B-exposed plants balance damage, repair, acclimation and adaptation responses in a photobiologically dynamic environment. (author)

Ecological responses to UV radiation: interactions between the biological effects of UV on plants and on associated organisms.

Science.gov (United States)

Paul, Nigel D; Moore, Jason P; McPherson, Martin; Lambourne, Cathryn; Croft, Patricia; Heaton, Joanna C; Wargent, Jason J

2012-08-01

Solar ultraviolet (UV)-B radiation (280-315 nm) has a wide range of effects on terrestrial ecosystems, yet our understanding of how UV-B influences the complex interactions of plants with pest, pathogen and related microorganisms remains limited. Here, we report the results of a series of experiments in Lactuca sativa which aimed to characterize not only key plant responses to UV radiation in a field environment but also consequential effects for plant interactions with a sap-feeding insect, two model plant pathogens and phylloplane microorganism populations. Three spectrally modifying filters with contrasting UV transmissions were used to filter ambient sunlight, and when compared with our UV-inclusive filter, L. sativa plants grown in a zero UV-B environment showed significantly increased shoot fresh weight, reduced foliar pigment concentrations and suppressed population growth of green peach aphid (Myzus persicae). Plants grown under a filter which allowed partial transmission of UV-A radiation and negligible UV-B transmission showed increased density of leaf surface phylloplane microbes compared with the UV-inclusive treatment. Effects of UV treatment on the severity of two plant pathogens, Bremia lactucae and Botrytis cinerea, were complex as both the UV-inclusive and zero UV-B filters reduced the severity of pathogen persistence. These results are discussed with reference to known spectral responses of plants, insects and microorganisms, and contrasted with established fundamental responses of plants and other organisms to solar UV radiation, with particular emphasis on the need for future integration between different experimental approaches when investigating the effects of solar UV radiation. Copyright © Physiologia Plantarum 2011.

Computational Photophysics in the Presence of an Environment

Science.gov (United States)

Nogueira, Juan J.; González, Leticia

2018-04-01

Most processes triggered by ultraviolet (UV) or visible (vis) light in nature take place in complex biological environments. The first step in these photophysical events is the excitation of the absorbing system or chromophore to an electronically excited state. Such an excitation can be monitored by the UV-vis absorption spectrum. A precise calculation of the UV-vis spectrum of a chromophore embedded in an environment is a challenging task that requires the consideration of several ingredients, besides an accurate electronic-structure method for the excited states. Two of the most important are an appropriate description of the interactions between the chromophore and the environment and accounting for the vibrational motion of the whole system. In this contribution, we review the most common theoretical methodologies to describe the environment (including quantum mechanics/continuum and quantum mechanics/molecular mechanics models) and to account for vibrational sampling (including Wigner sampling and molecular dynamics). Further, we illustrate in a series of examples how the lack of these ingredients can lead to a wrong interpretation of the electronic features behind the UV-vis absorption spectrum.

Increased exposure to UV-B radiation during early development leads to enhanced photoprotection and improved long-term performance in Lactuca sativa.

Science.gov (United States)

Wargent, Jason J; Elfadly, Eslam M; Moore, Jason P; Paul, Nigel D

2011-08-01

Plant responses to solar UV radiation are numerous and have often been considered from a perspective of negative outcomes for plant productivity. In this study, we used two experimental approaches consisting of: (1) field-based spectrally modifying filters in addition to (2) controlled indoor exposure to UV-B, to examine the effects of UV radiation on growth and photosynthetic performance of lettuce (Lactuca sativa L.) seedlings. Various aspects of growth were affected in plants grown under a UV-inclusive environment compared to a UV-depleted environment, including reductions in leaf expansion, increases in leaf thickness and the rate of net photosynthesis. After transplantation to a uniform field environment, lettuce plants initially propagated under the UV-inclusive environment exhibited higher harvestable yields than those from a UV-depleted environment. In controlled conditions, photosynthetic rates were higher in plants grown in the presence of UV-B radiation, and relative growth of plants pre-acclimatized to UV-B was also increased, in addition to higher maximum photochemical efficiency of photosystem II (PSII) (F(v) /F(m) ) following subsequent exposure to high photosynthetically active radiation (PAR) and temperature stress. Our findings are discussed within the context of sustainability in agriculture and the paradigm shift in photobiology which such beneficial responses to UV radiation could represent. © 2011 Blackwell Publishing Ltd.

Effects of the summer holiday season on UV filter and illicit drug concentrations in the Korean wastewater system and aquatic environment.

Science.gov (United States)

Kim, Ki Yong; Ekpeghere, Kalu Ibe; Jeong, Hee-Jin; Oh, Jeong-Eun

2017-08-01

Seasonal variations in the concentrations of eight ultraviolet (UV) filters and 22 illicit drugs including their metabolites in the Korean aquatic environment were investigated. Seawater samples from three beaches, water samples from two rivers, and influents and effluents from three wastewater treatment plants were analyzed. The UV filter concentrations in the seawater, river water, and effluent samples were 39.4-296, 35.4-117, and 6.84-51.1 ng L -1 , respectively. The total UV filter concentrations in the seawater samples were 1.9-4.4 times higher at the peak of the holiday season than outside the peak holiday season. An environmental risk assessment showed that ethylhexyl methoxy cinnamate (EHMC) could cause adverse effects on aquatic organisms in the seawater at the three beaches during the holiday period. Seven of the 22 target illicit drugs including their metabolites were detected in the wastewater influent samples, and the total illicit drug concentrations in the influent samples were 0.08-65.4 ng L -1 . The estimated daily consumption rates for cis-tramadol (Cis-TRM), methamphetamine (MTP), meperidine (MEP), and codeine (COD) were 25.7-118.4, 13.8-36.1, 1.36-12.6, and 1.75-8.64 mg d -1 (1000 people) -1 , respectively. In popular vacation area, the illicit drug consumption rates (Cis-TRM, MTP and MEP) were 1.6-2.6 times higher at the peak of the summer holiday season than at the beginning of the summer. Copyright © 2017 Elsevier Ltd. All rights reserved.

The effects of UV-B radiation on European heathland species

International Nuclear Information System (INIS)

Björn, L.O.; Callaghan, T.V.; Johnsen, I.; Lee, J.A.; Manetas, Y.; Paul, N.D.; Sonesson, M.; Wellburn, A.R.; Coop, D.; Heide-Jørgensen, H.S.; Gehrke, C.; Gwynn-Jones, D.; Johanson, U.; Kyparissis, A.; Levizou, E.; Nikolopoulos, D.; Petropoulou, Y.; Stephanou, M.

1997-01-01

The effects of enhanced UV-B radiation on three examples of European shrub-dominated vegetation were studied in situ. The experiments were in High Arctic Greenland, northern Sweden and Greece, and at all sites investigated the interaction of enhanced UV-B radiation (simulating a 15% reduction in the ozone layer) with artificially increased precipitation. The Swedish experiment also involved a study of the interaction between enhanced UV-B radiation and elevated CO 2 (600 ppm). These field studies were supported by an outdoor controlled environment study in the United Kingdom involving modulated enhancement of UV-B radiation in combination with elevated CO 2 (700 ppm). Effects of the treatments on plant growth, morphology, phenology and physiology were measured. The effects observed were species specific, and included both positive and negative responses to the treatments. In general the negative responses to UV-B treatments of up to three growing seasons were small, but included reductions in shoot growth and premature leaf senescence. Positive responses included a marked increase in flowering in some species and a stimulation of some photosynthetic processes. UV-B treatment enhanced the drought tolerance of Pinus pinea and Pinus halepensis by increasing leaf cuticle thickness. In general, there were few interactions between the elevated CO 2 and enhanced UV-B treatments. There was evidence to suggest that although the negative responses to the treatments were small, damage may be increasing with time in some long-lived woody perennials. There was also evidence in the third year of treatments for effects of UV-B on insect herbivory in Vaccinium species. The experiments point to the necessity for long-term field investigations to predict the likely ecological consequences of increasing UV-B radiation. (author)

An Expanded UV Irradiance Database from TOMS Including the Effects of Ozone, Clouds, and Aerosol Attenuation

Science.gov (United States)

Herman, J.; Krotkov, N.

2003-01-01

The TOMS UV irradiance database (1978 to 2003) has been expanded to include five new products (noon irradiance at 305,310,324, and 380 nm, and noon erythemal-weighted irradiance), in addition to the existing erythemal daily exposure, that permit direct comparisons with ground-based measurements from spectrometers and broadband instruments. The new data are available on http://toms.gsfc.nasa.gov/>http://toms.gsfc.nasa.gov. Comparisons of the TOMS estimated irradiances with ground-based instruments are given along with a review of the sources of known errors, especially the recent improvements in accounting for aerosol attenuation. Trend estimations from the new TOMS irradiances permit the clear separation of changes caused by ozone and those caused by aerosols and clouds. Systematic differences in cloud cover are shown to be the most important factor in determining regional differences in UV radiation reaching the ground for locations at the same latitude (e.g., the summertime differences between Australia and the US southwest).

Crystal Structure of the Phage T4 Recombinase UvsX and Its Functional Interaction with the T4 SF2 Helicase UvsW

Energy Technology Data Exchange (ETDEWEB)

Gajewski, Stefan; Webb, Michael R.; Galkin, Vitold; Egelman, Edward H.; Kreuzer, Kenneth N.; White, Stephen W. (Duke); (UV); (SJCH)

2012-07-11

Bacteriophage T4 provides an important model system for studying the mechanism of homologous recombination. We have determined the crystal structure of the T4 UvsX recombinase, and the overall architecture and fold closely resemble those of RecA, including a highly conserved ATP binding site. Based on this new structure, we reanalyzed electron microscopy reconstructions of UvsX-DNA filaments and docked the UvsX crystal structure into two different filament forms: a compressed filament generated in the presence of ADP and an elongated filament generated in the presence of ATP and aluminum fluoride. In these reconstructions, the ATP binding site sits at the protomer interface, as in the RecA filament crystal structure. However, the environment of the ATP binding site is altered in the two filament reconstructions, suggesting that nucleotide cannot be as easily accommodated at the protomer interface of the compressed filament. Finally, we show that the phage helicase UvsW completes the UvsX-promoted strand-exchange reaction, allowing the generation of a simple nicked circular product rather than complex networks of partially exchanged substrates.

Degradation of Iodinated Contrast Media in Aquatic Environment by Means of UV, UV/TiO2 Process, and by Activated Sludge.

Science.gov (United States)

Borowska, Ewa; Felis, Ewa; Żabczyński, Sebastian

Iodinated contrast media (ICM), which are used for radiological visualization of human tissue and cardiovascular system, are poorly biodegradable; hence, new methods of their removal are sought. In this study, the effectiveness of selected X-ray ICM removal by means of UV and UV/TiO 2 pretreatment processes from synthetic hospital wastewater was demonstrated. The following compounds were investigated: iodipamide, iohexol, and diatrizoate. The experiments were as follows: (i) estimated susceptibility of the ICM to decay by UV radiation in different aquatic matrices, (ii) determined an optimal retention time of hospital wastewater in the UV reactor, (iii) determined optimum TiO 2 concentration to improve the effectiveness of the UV pretreatment, and (iv) investigated removal of ICM by combination of the photochemical and biological treatment methods. The quantum yields of selected ICM decay in deionized water (pH = 7.0) were established as 0.006, 0.004, and 0.029 for iohexol, diatrizoate, and iodipamide, respectively. Furthermore, the experiments revealed that diatrizoate and iohexol removal in the UV/TiO 2 process is more efficient than in UV process alone. For diatrizoate, the removal efficiency equaled to 40 and 30 %, respectively, and for iohexol, the efficiency was 38 and 27 %, respectively. No significant increase in iodipamide removal in UV and UV/TiO 2 processes was observed (29 and 28 %, respectively). However, highest removal efficiency was demonstrated in synthetic hospital wastewater with the combined photochemical and biological treatment method. The removal of diatrizoate and iohexol increased to at least 90 %, and for iodipamide, to at least 50 %.

The regrowth of phytoplankton cultures after UV disinfection

International Nuclear Information System (INIS)

Martínez, Lucía F.; Mahamud, Manuel M.; Lavín, Antonio G.; Bueno, Julio L.

2013-01-01

Highlights: ► Phytoplankton cultures were placed in a rich medium after UV-C irradiation. ► Flow cytometry and PAM were used for determining cell viability. ► The behavior differs from that of cultures kept in their original environment. ► Chlorella autotrophica recovers between 5 and 10 days after the treatment. ► Phaeocystis globosa shows only a slight recovery for low-dose UV-radiation exposure. - Abstract: This study addresses how cultures of three phytoplankton species –Chaetoceros calcitrans, Chlorella autotrophica and Phaeocystis globosa – can recover from the effects of UV-C exposure if the cells are placed in a rich medium. Flow cytometry and pulse amplitude modulation (PAM) were used to determine cell recovery after UV treatment. The recovery of C. calcitrans was complete 9 days after treatment. For C. autotrophica, the recovery was noticeable 5 days after treatment. P. globosa only recovered if the UV dose did not exceed 7.3 × 10 5 μWs/cm 2 . The recovery of the UV-treated cultures introduced to a regrowth medium, compared with the recovery of the irradiated cultures kept in their original environment, had two main characteristics: cell recovery was slower but was more efficient. This pattern of recovery has very important implications for real ballast water management systems because such systems discharge treated water into the environment

Mirror coatings for large aperture UV optical infrared telescope optics

Science.gov (United States)

Balasubramanian, Kunjithapatham; Hennessy, John; Raouf, Nasrat; Nikzad, Shouleh; Del Hoyo, Javier; Quijada, Manuel

2017-09-01

Large space telescope concepts such as LUVOIR and HabEx aiming for observations from far UV to near IR require advanced coating technologies to enable efficient gathering of light with important spectral signatures including those in far UV region down to 90nm. Typical Aluminum mirrors protected with MgF2 fall short of the requirements below 120nm. New and improved coatings are sought to protect aluminum from oxidizing readily in normal environment causing severe absorption and reduction of reflectance in the deep UV. Choice of materials and the process of applying coatings present challenges. Here we present the progress achieved to date with experimental investigations of coatings at JPL and at GSFC and discuss the path forward to achieve high reflectance in the spectral region from 90 to 300nm without degrading performance in the visible and NIR regions taking into account durability concerns when the mirrors are exposed to normal laboratory environment as well as high humidity conditions. Reflectivity uniformity required on these mirrors is also discussed.

The UVR8 UV-B Photoreceptor: Perception, Signaling and Response

Science.gov (United States)

Tilbrook, Kimberley; Arongaus, Adriana B.; Binkert, Melanie; Heijde, Marc; Yin, Ruohe; Ulm, Roman

2013-01-01

Ultraviolet-B radiation (UV-B) is an intrinsic part of sunlight that is accompanied by significant biological effects. Plants are able to perceive UV-B using the UV-B photoreceptor UVR8 which is linked to a specific molecular signaling pathway and leads to UV-B acclimation. Herein we review the biological process in plants from initial UV-B perception and signal transduction through to the known UV-B responses that promote survival in sunlight. The UVR8 UV-B photoreceptor exists as a homodimer that instantly monomerises upon UV-B absorption via specific intrinsic tryptophans which act as UV-B chromophores. The UVR8 monomer interacts with COP1, an E3 ubiquitin ligase, initiating a molecular signaling pathway that leads to gene expression changes. This signaling output leads to UVR8-dependent responses including UV-B-induced photomorphogenesis and the accumulation of UV-B-absorbing flavonols. Negative feedback regulation of the pathway is provided by the WD40-repeat proteins RUP1 and RUP2, which facilitate UVR8 redimerization, disrupting the UVR8-COP1 interaction. Despite rapid advancements in the field of recent years, further components of UVR8 UV-B signaling are constantly emerging, and the precise interplay of these and the established players UVR8, COP1, RUP1, RUP2 and HY5 needs to be defined. UVR8 UV-B signaling represents our further understanding of how plants are able to sense their light environment and adjust their growth accordingly. PMID:23864838

Fluorescent minerals - A potential source of UV protection and visible light for the growth of green algae and cyanobacteria in extreme cosmic environments

Science.gov (United States)

Omairi, Tareq; Wainwright, Milton

2015-07-01

We propose that green algae (Chlorella variabilis and Dunaliella tertiolecta) and cyanobacteria (Synechococcus elongatus and Nostoc commune) can grow inside fluorescent rock minerals which convert damaging UV light to visible light, thereby allowing these organisms to survive and thrive in UV-rich environments without (or with limited) visible light, which would otherwise be inimical to them. The four microorganisms were incubated inside fluorescent rocks composed of fluorite, calcite and pyrite. The resultant growth was then measured following exposure to UV radiation, with the use of optical density and measurement of chlorophyll concentration. Results show that the microorganisms were shielded from harmful UV in these semi-transparent rocks, while at the same time benefiting from the fact that the minerals converted UV to visible light; this have been shown by a statistically significant increase in their growth, which although lower than when the cells were incubated in sunlight, was significantly higher than in controls incubated in the dark.

The Effects of UV Light on the Chemical and Mechanical Properties of a Transparent Epoxy-Diamine System in the Presence of an Organic UV Absorber

Directory of Open Access Journals (Sweden)

Saeid Nikafshar

2017-02-01

Full Text Available Despite several excellent properties including low shrinkage, good chemical resistance, curable at low temperatures and the absence of byproducts or volatiles, epoxy resins are susceptible to ultra violet (UV damage and their durability is reduced substantially when exposed to outdoor environments. To overcome this drawback, UV absorbers have been usually used to decrease the rate of UV degradation. In this present study, the effects of UV light on the chemical, mechanical and physical properties of cured epoxy structure, as well as the effect of an organic UV absorber, Tinuvin 1130, on the epoxy properties were investigated. Chemical changes in a cured epoxy system as a result of the presence and absence of Tinuvin 1130 were determined using Fourier transform infrared spectroscopy (FT-IR analyses. The effect of Tinuvin 1130 on the surface morphology of the epoxy systems was also investigated by scanning electron microscopy (SEM imaging. Additionally, the glass transition temperatures (Tg before and during UV radiation were measured. After an 800 h UV radiation, mechanical test results revealed that the lack of the UV absorber can lead to a ~30% reduction in tensile strength. However, in the presence of Tinuvin 1130, the tensile strength was reduced only by ~11%. It was hypothesized that the use of Tinuvin 1130, as an organic UV absorber in the epoxy-amine system, could decrease the undesirable effects, arising from exposure to UV light.

Fluorescent minerals--A potential source of UV protection and visible light for the growth of green algae and cyanobacteria in extreme cosmic environments.

Science.gov (United States)

Omairi, Tareq; Wainwright, Milton

2015-07-01

We propose that green algae (Chlorella variabilis and Dunaliella tertiolecta) and cyanobacteria (Synechococcus elongatus and Nostoc commune) can grow inside fluorescent rock minerals which convert damaging UV light to visible light, thereby allowing these organisms to survive and thrive in UV-rich environments without (or with limited) visible light, which would otherwise be inimical to them. The four microorganisms were incubated inside fluorescent rocks composed of fluorite, calcite and pyrite. The resultant growth was then measured following exposure to UV radiation, with the use of optical density and measurement of chlorophyll concentration. Results show that the microorganisms were shielded from harmful UV in these semi-transparent rocks, while at the same time benefiting from the fact that the minerals converted UV to visible light; this have been shown by a statistically significant increase in their growth, which although lower than when the cells were incubated in sunlight, was significantly higher than in controls incubated in the dark. Copyright © 2015 The Committee on Space Research (COSPAR). Published by Elsevier Ltd. All rights reserved.

Climate Variability, Dissolved Organic Carbon, UV Exposure, and Amphibian Decline

Science.gov (United States)

Brooks, P. D.; O'Reilly, C. M.; Diamond, S.; Corn, S.; Muths, E.; Tonnessen, K.; Campbell, D. H.

2001-12-01

Increasing levels of UV radiation represent a potential threat to aquatic organisms in a wide range of environments, yet controls on in situ variability on UV exposure are relatively unknown. The primary control on the penetration of UV radiation in surface water environments is the amount of photoreactive dissolved organic carbon (DOC). Consequently, biogeochemical processes that control the cycling of DOC also affect the exposure of aquatic organisms to UV radiation. Three years of monitoring UV extinction and DOC composition in Rocky Mountain, Glacier, Sequoia/ Kings Canyon, and Olympic National Parks demonstrate that the amount of fulvic acid DOC is much more important than the total DOC pool in controlling UV attenuation. This photoreactive component of DOC originates primarily in soil, and is subject both to biogeochemical controls (e.g. temperature, moisture, vegetation, soil type) on production, and hydrologic controls on transport to surface water and consequently UV exposure to aquatic organisms. Both of these controls are positively related to precipitation with greater production and transport associated with higher precipitation amounts. For example, an approximately 20 percent reduction in precipitation from 1999 to 2000 resulted in a 27% - 59% reduction in the amount of photoreactive DOC at three sites in Rocky Mountain National Park. These differences in the amount of hydrophobic DOC result in an increase in UV exposure in the aquatic environment by a factor of 2 or more. Implications of these findings for observed patterns of amphibian decline will be discussed.

Microbial Removal Efficiency of UV in Tehran Shahid Mahallati Wastewater Treatment Plant

Directory of Open Access Journals (Sweden)

Reza Dabbagh

2009-03-01

Full Text Available Shahid Mahallati Wastewater Treatment Plant was selected for installing a UV disinfection unit to investigate its germicidal effect on microbial removal. Low pressure mercury lamps were used to generate germicidal ultraviolet radiation (UV-C. The UV system was operated over a period of 6 months that included both warm and cold seasons. A maximum UV disinfection efficiency of 14.4m3/h was recorded for the system on the basis of design criteria within turbidity ranges of 9 to 32 NTU. The minimum UV dose applied in the UV unit was 40000 µW.s/cm2 and the highest bacterial density in the UV unit influent was 5.6*107. Effluent total coliform or fecal coliform enumeration after exposure to UV ray showed the microbial density decreasing from four logs, or 99.99%, to as high as six logs, or 99.9999% removal efficiency, under different conditions. Effluent microbial densities in terms of total and fecal coliforms were below 1000MPN/100mL and 400MPN/100mL, respectively. These values comply with wastewater discharge or agricultural irrigation standards according to Iran Department of Environment. From our results, it is concluded that UV disinfection may be an effective technique for wastewater disinfection in Iranian wastewater treatment plants.

Potential risks from UV/H2O2 oxidation and UV photocatalysis: A review of toxic, assimilable, and sensory-unpleasant transformation products.

Science.gov (United States)

Wang, Wen-Long; Wu, Qian-Yuan; Huang, Nan; Xu, Zi-Bin; Lee, Min-Yong; Hu, Hong-Ying

2018-05-15

UV based advanced oxidation processes (UV-AOPs) that efficiently eliminate organic pollutants during water treatment have been the subject of numerous investigations. Most organic pollutants are not completely mineralized during UV-AOPs but are partially oxidized into transformation products (TPs), thereby adding complexity to the treated water and posing risks to humans, ecological systems, and the environment. While the degradation kinetics and mechanisms of pollutants have been widely documented, there is little information about the risks associated with TPs. In this review, we have collated recent knowledge about the harmful TPs that are generated in UV/H 2 O 2 and UV photocatalysis, two UV-AOPs that have been studied extensively. Toxic and assimilable TPs were ubiquitously observed in more than 80% of UV-AOPs of organic pollutants, of which the toxicity and assimilability levels changed with variations in the reaction conditions, such as the UV fluence and oxidant dosage. Previous studies and modeling assessments showed that toxic and assimilable TPs may be generated during hydroxylation, dealkylation, decarboxylation, and deamination. Among various reactions, TPs generated from dealkylation and decarboxylation were generally less and more toxic than the parent pollutants, respectively; TPs generated from decarboxylation and deamination were generally less and more assimilable than the parent pollutants, respectively. There is also potential concern about the sensory-unpleasant TPs generated by oxidations and subsequent metabolism of microorganisms. In this overview, we stress the need to include both the concentrations of organic pollutants and the evaluations of the risks from TPs for the quality assessments of the water treated by UV-AOPs. Copyright © 2018 Elsevier Ltd. All rights reserved.

The Skin Microbiome: Is It Affected by UV-induced Immune Suppression?

Science.gov (United States)

Patra, VijayKumar; Byrne, Scott N.; Wolf, Peter

2016-01-01

Human skin apart from functioning as a physical barricade to stop the entry of pathogens, also hosts innumerable commensal organisms. The skin cells and the immune system constantly interact with microbes, to maintain cutaneous homeostasis, despite the challenges offered by various environmental factors. A major environmental factor affecting the skin is ultraviolet radiation (UV-R) from sunlight. UV-R is well known to modulate the immune system, which can be both beneficial and deleterious. By targeting the cells and molecules within skin, UV-R can trigger the production and release of antimicrobial peptides, affect the innate immune system and ultimately suppress the adaptive cellular immune response. This can contribute to skin carcinogenesis and the promotion of infectious agents such as herpes simplex virus and possibly others. On the other hand, a UV-established immunosuppressive environment may protect against the induction of immunologically mediated skin diseases including some of photodermatoses such as polymorphic light eruption. In this article, we share our perspective about the possibility that UV-induced immune suppression may alter the landscape of the skin’s microbiome and its components. Alternatively, or in concert with this, direct UV-induced DNA and membrane damage to the microbiome may result in pathogen associated molecular patterns (PAMPs) that interfere with UV-induced immune suppression. PMID:27559331

The skin microbiome: Is it affected by UV-induced immune suppression?

Directory of Open Access Journals (Sweden)

Vijaykumar Patra

2016-08-01

Full Text Available Human skin apart from functioning as a physical barricade to stop the entry of pathogens, also hosts innumerable commensal organisms. The skin cells and the immune system constantly interact with microbes, to maintain cutaneous homeostasis, despite the challenges offered by various environmental factors. A major environmental factor affecting the skin is ultraviolet radiation UV-R from sunlight. UV-R is well known to modulate the immune system, which can be both beneficial and deleterious. By targeting the cells and molecules within skin, UV-R can trigger the production and release of antimicrobial peptides (AMPs, affect the innate immune system and ultimately suppress the adaptive cellular immune response. This can contribute to skin carcinogenesis and the promotion of infectious agents such as herpes simplex virus and possibly others. On the other hand, a UV-established immunosuppressive environment may protect against the induction of immunologically mediated skin diseases including some of photodermatoses such as polymorphic light eruption. In this article, we share our perspective about the possibility that UV-induced immune suppression may alter the landscape of the skin's microbiome and its components. Alternatively, or in concert with this, direct UV-induced DNA and membrane damage to the microbiome may result in pathogen associated molecular patterns (PAMPs that interfere with UV-induced immune suppression.

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.

Application of UV Imaging in Formulation Development

DEFF Research Database (Denmark)

Sun, Yu; Østergaard, Jesper

2017-01-01

defining formulation behavior after exposure to the aqueous environments and pharmaceutical performance is critical in pharmaceutical development, manufacturing and quality control of drugs. UV imaging has been explored as a tool for qualitative and quantitative characterization of drug dissolution...... related to the structural properties of the drug substance or formulation can be monitored. UV imaging is a non-intrusive and simple-to-operate analytical technique which holds potential for providing a mechanistic foundation for formulation development. This review aims to cover applications of UV...

Alfalfa seedlings grown outdoors are more resistant to UV-induced DNA damage than plants grown in a UV-free environmental chamber

International Nuclear Information System (INIS)

Takayanagi, Shinnosuke; Trunk, J.G.; Sutherland, J.C.; Sutherland, B.M.

1994-01-01

The relative UV sensitivities of alfalfa seedlings grown outdoors versus plants grown in a growth chamber under UV-filtered cool white fluorescent bulbs have been determined using three criteria: (1) level of endogenous DNA damage as sites for the UV endonuclease from Micrococcus luteus, (2) susceptibility to pyrimidine dimer induction by a UV challenge exposure and (3) ability to repair UV-induced damage. We find that outdoor-grown plants contain approximately equal frequencies of endogenous DNA damages, are less susceptible to dimer induction by a challenge exposure of broad-spectrum UV and photorepair dimers more rapidly than plants grown in an environmental chamber under cool white fluorescent lamps plus a filter removes most UV radiation. These data suggest that plants grown in a natural environment would be less sensitive to UVB-induced damage than would be predicted on the basis of studies on plants grown under minimum UV. (author)

The mechanisms of UV mutagenesis

International Nuclear Information System (INIS)

Ikehata, Hironobu; Ono, Tetsuya

2011-01-01

Ultraviolet (UV) light induces specific mutations in the cellular and skin genome such as UV-signature and triplet mutations, the mechanism of which has been thought to involve translesion DNA synthesis (TLS) over UV-induced DNA base damage. Two models have been proposed: ''error-free'' bypass of deaminated cytosine-containing cyclobutane pyrimidine dimers (CPDs) by DNA polymerase η, and error-prone bypass of CPDs and other UV-induced photolesions by combinations of TLS and replicative DNA polymerases-the latter model has also been known as the two-step model, in which the cooperation of two (or more) DNA polymerases as misinserters and (mis)extenders is assumed. Daylight UV induces a characteristic UV-specific mutation, a UV-signature mutation occurring preferentially at methyl-CpG sites, which is also observed frequently after exposure to either UVB or UVA, but not to UVC. The wavelengths relevant to the mutation are so consistent with the composition of daylight UV that the mutation is called solar-UV signature, highlighting the importance of this type of mutation for creatures with the cytosine-methylated genome that are exposed to the sun in the natural environment. UVA has also been suggested to induce oxidative types of mutation, which would be caused by oxidative DNA damage produced through the oxidative stress after the irradiation. Indeed, UVA produces oxidative DNA damage not only in cells but also in skin, which, however, does not seem sufficient to induce mutations in the normal skin genome. In contrast, it has been demonstrated that UVA exclusively induces the solar-UV signature mutations in vivo through CPD formation. (author)

Health hazards of UV radiation

International Nuclear Information System (INIS)

Matthes, R.

1994-01-01

The author describes the effects and health risks of UV exposure. This includes UV effects on the DNS, the eyes, the immune system, and the skin. Finally, recommendations are given for protection against excessive UV exposure on the basis of the IRPA/INIRC guidelines. (orig.) [de

In the shadow of the Cosmetic Directive — Inconsistencies in EU environmental hazard classification requirements for UV-filters

International Nuclear Information System (INIS)

Sobek, A.; Bejgarn, S.; Rudén, C.; Molander, L.; Breitholtz, M.

2013-01-01

UV-filters are chemicals with potentially environmental hazardous properties. In the European Union (EU), UV-filters contained in sunscreen products are currently regulated by the Cosmetic Directive (from July 2013 by the Cosmetic Products Regulation). Environmental hazard classifications according to the regulation on classification, labelling and packaging of substances and mixtures (CLP) must be determined for UV-filters contained in industrial chemical products, whereas UV-filters contained in sunscreens are exempted from CLP. In this study we determined the potential environmental hazard classifications of UV-filters and sunscreen products if the CLP regulation was to be required for cosmetic products. Two sunscreen products were evaluated in accordance with the aquatic environmental hazard criteria for mixtures. The results highlight that the inconsistencies in the current EU regulation of UV filters hamper the risk management of environmental hazards of UV filters used in cosmetic products. Almost 50% of the investigated UV-filters approved for use in cosmetic products on the European market according to the current Cosmetic Directive were identified to meet the CLP classification as being hazardous to the aquatic environment. Assuming a worst-case scenario, the two examined sunscreens could both be classified as hazardous to the aquatic environment with long-lasting effects according to CLP classification criteria. Hence, if the CLP regulation was applicable to sunscreen products, both brands could potentially be labelled with the environmental hazard pictogram and associated hazard and precautionary statements. Including cosmetic products, and thereby sunscreens, in the CLP regulation would contribute to a more harmonized and transparent regulation of potentially hazardous substances on the EU market. - Highlights: • UV-filters are used in both cosmetic and industrial products/applications • UV-filters in cosmetic products are excluded from CLP • We

UV Impacts Avoided by the Montreal Protocol

Science.gov (United States)

Newman, Paul; McKenzie, Richard

2010-01-01

Temporal and geographical variabilities in the future "World Expected" UV environment are compared with the "World Avoided", which would have occurred without the Montreal Protocol on protection of the ozone layer and its subsequent amendments and adjustments. Based on calculations of clear-sky UV irradiances, the effects of the Montreal Protocol have been hugely beneficial to avoid the health risks, such as skin cancer, which are associated with high UV, while there is only a small increase in health risks, such as vitamin D deficiency, that are associated with low UV. However, interactions with climate change may lead to changes in cloud and albedo, and possibly behavioural changes which could also be important.

The responses to supplementary of UV radiation of some temperate meadow species

International Nuclear Information System (INIS)

Cooley, N.M.

2002-01-01

Full text: The growth and development of various meadow species was monitored while growing under enhanced UV-radiation in the natural light environment. Growth responses to supplementary ultraviolet-B (UV-B+A) and ultraviolet-A (UV-A) were compared to the ambient daylight treatment for Bellis perennis, Cardamine pratensis, Cynosurus critatus and Ranunculus ficaria. When the response of ultraviolet A (UV-A) treated plants were compared with those of the UV-B+A, differences were found which varied according to the species and parameter investigated. To further understand the growth responses of the UV-A treatment and their relationship to the UV-B responses polychromatic action spectra in the natural environment was employed B perennis had an action maximum in the UV B (280-315 nm) while C cristatus demonstrates no action in the UV-B but action in the UV-A region (315-400 nm.). To enable further explanation of the effects of elevated UV radiation on the meadow plants Arabidopsis thaliana ecotypes and mutants were investigated. A thaliana ecotypes dry weight accumulation was found to respond differently to the UV treatments. UV B+A treatment was found to inhibit dry weight accumulation in most ecotypes. When UV B+A induced inhibition was expressed in terms of ambient growth rate for each ecotype a linear relationship could be derived. The higher the growth rate the more susceptible the ecotype was to UV-B+A inhibition. The pertinence of the UV-A treatment and UV protocol is discussed. It is suggested that UV responses could alter the diversity of the meadow equilibrium

UV reflectance is associated with environmental conditions in Palaearctic Pieris napi (Lepidoptera: Pieridae).

Science.gov (United States)

Stella, David; Pecháček, Pavel; Meyer-Rochow, Victor Benno; Kleisner, Karel

2018-06-01

The subject of our investigation was the visual features of wing color with special focus on the UV reflectance in the green-veined white butterfly (Pieris napi). Previous studies had concluded that UV reflectance on dorsal wing surfaces is found only in the female P. napi. Based on UV sensitive photography, we analyzed a correlation between 12 geographic and environmental factors and UV reflectance patterns on 3 patches on the forewings of 407 P. napi specimens from the Palaearctic region. Results had shown that females significantly differ from males: they exhibit a 25% higher UV reflectance. To investigate whether and how UV reflectance levels on the forewings and hindwings of both sexes are influenced by the environment, we performed a principal component analysis (PCA) with several environmental variables. For several variables (in particular, latitude and longitude, mean annual temperature and precipitation, and temperature annual range and altitude), the generalized linear model (GLM) model revealed a significant correlation in both sexes. This suggests a link between UV reflectance levels and the environment and distribution of P. napi. We found that stronger UV reflectance is associated with generally more hostile environments and concluded that large-scale environmental factors influence the UV reflectance on the forewings of both male and female green-veined white butterflies. © 2016 Institute of Zoology, Chinese Academy of Sciences.

Effects of UV radiation on phytoplankton

Science.gov (United States)

Smith, Raymond C.; Cullen, John J.

1995-07-01

It is now widely documented that reduced ozone will result in increased levels of ultraviolet (UV) radiation, especially UV-B (280-320nm), incident at the surface of the earth [Watson, 1988; Anderson et al., 1991; Schoeberl and Hartmann, 1991; Frederick and Alberts, 1991; WMO, 1991; Madronich, 1993; Kerr and McElroy, 1993], and there is considerable and increasing evidence that these higher levels of UV-B radiation may be detrimental to various forms of marine life in the upper layers of the ocean. With respect to aquatic ecosystems, we also know that this biologically- damaging mid-ultraviolet radiation can penetrate to ecologically- significant depths in marine and freshwater systems [Jerlov, 1950; Lenoble, 1956; Smith and Baker, 1979; Smith and Baker, 1980; Smith and Baker, 1981; Kirk et al., 1994]. This knowledge, plus the dramatic decline in stratospheric ozone over the Antarctic continent each spring, now known to be caused by anthropogenically released chemicals [Solomon, 1990; Booth et al., 1994], has resulted in increased UV-environmental research and a number of summary reports. The United Nations Environmental Program (UNEP) has provided recent updates with respect to the effects of ozone depletion on aquatic ecosystems (Hader, Worrest, Kumar in UNEP 1989, 1991, Hader, Worrest, Kumar and Smith UNEP 1994) and the Scientific Committee on Problems of the Environment (SCOPE) has provided [SCOPE, 1992] a summary of the effects of increased UV radiation on biological systems. SCOPE has also reported [SCOPE, 1993] on the effects of increased UV on the biosphere. In addition, several books have recently been published reviewing various aspects of environmental UV photobiology [Young et al., 1993], UV effects on humans, animals and plants [Tevini, 1993], the biological effects of UV radiation in Antarctica [Weiler and Penhale, 1994], and UV research in freshwater ecosystems [Williamson and Zagarese, 1994]. Several other reviews are relevant [NAS, 1984; Caldwell

Transverse effects in UV FELs

International Nuclear Information System (INIS)

Small, D.W.; Wong, R.K.; Colson, W.B.

1995-01-01

In an ultraviolet Free Electron Laser (UV FEL), the electron beam size can be approximately the same as the optical mode size. The performance of a UV FEL is studied including the effect of emittance, betatron focusing, and external focusing of the electron beam on the transverse optical mode. The results are applied to the Industrial Laser Consortium's UV FEL

The UV Sensor Onboard the Mars Science Laboratory Mission: Correction and Generation of UV Fluxes

Science.gov (United States)

Vicente-Retortillo, Á.; Martinez, G.; Renno, N. O.; Lemmon, M. T.; Gomez-Elvira, J.

2017-12-01

The Rover Environmental Monitoring Station UV sensor (UVS) onboard the Mars Science Laboratory mission has completed more than 1750 sols of measurements, providing an unprecedented coverage ranging from diurnal to interannual times scales [1,2]. The UVS is comprised of six photodiodes to measure the UV flux in the ranges 200-380, 320-380, 280-320, 200-280, 230-290 and 300-350 nm [3]. UV fluxes in units of W/m2 can be found in the NASA Planetary Data System (PDS). However, dust deposition on the UVS and a non-physical discontinuity in the calibration functions when the solar zenith angle is above 30º cause errors in these fluxes that increase with time. We have developed a technique to correct UV fluxes from the effects of dust degradation and inconsistencies in the angular response of the UVS. The photodiode output currents (available in the PDS as lower-level TELRDR products), ancillary data records (available in the PDS as ADR products) and dust opacity values derived from Mastcam observations are used for performing the corrections. The corrections have been applied to the UVA band (320-380 nm) for the first 1000 sols of the mission, providing excellent results [4]. We plan to correct the UV fluxes on each of the six UVS bands and to make these results available in the PDS. Data products generated by this study will allow comparisons of the UV radiation environment at Gale crater with that at the locations of the future missions ExoMars 2020 and Mars 2020, as well as the assessment of the potential survivability of biological contaminants brought to Mars from Earth. References: [1] Smith, M. D., et al. (2016), Aerosol optical depth as observed by the Mars Science Laboratory REMS UV photodiodes, Icarus, 280, 234-248. [2] Vicente-Retortillo, Á., et al. (2017), Determination of dust aerosol particle size at Gale Crater using REMS UVS and Mastcam measurements, Geophys. Res. Lett., 44, 3502-3508. [3] Gómez-Elvira, J., et al. (2012), REMS: The environmental sensor

Experimental Evolution of UV-C Radiation Tolerance: Emergence of Adaptive and Non-Adaptive Traits in Escherichia coli Under Differing Flux Regimes

Science.gov (United States)

Moffet, A.; Okansinski, A.; Sloan, C.; Grace, J. M.; Paulino-Lima, I. G.; Gentry, D.; Rothschild, L. J.; Camps, M.

2014-12-01

High-energy ultraviolet (UV-C) radiation is a significant challenge to life in environments such as high altitude areas, the early Earth, the Martian surface, and space. As UV-C exposure is both a selection pressure and a mutagen, adaptation dynamics in such environments include a high rate of change in both tolerance-related and non-tolerance-related genes, as well changes in linkages between the resulting traits. Determining the relationship between the intensity and duration of the UV-C exposure, mutation rate, and emergence of UV-C resistance will inform our understanding of both the emergence of radiation-related extremophily in natural environments and the optimal strategies for generating artificial extremophiles. In this study, we iteratively exposed an Escherichia colistrain to UV-C radiation of two different fluxes, 3.3 J/m^2/s for 6 seconds and 0.5 J/m^2/s for 40 seconds, with the same overall fluence of 20 J/m^2. After each iteration, cells from each exposure regime were assayed for increased UV-C tolerance as an adaptive trait. The exposed cells carried a plasmid bearing a TEM beta-lactamase gene, which in the absence of antibiotic treatment is a neutral reporter for mutagenesis. Sequencing of this gene allowed us to determine the baseline mutation frequency for each flux. As an additional readout for adaptation, the presence of extended-spectrum beta-lactamase mutations was tested by plating UV-exposed cultures in cefotaxime plates. We observed an increase of approximately one-million-fold in UV-C tolerance over seven iterations; no significant difference between the two fluxes was found. Future work will focus on identifying the genomic changes responsible for the change in UV-C tolerance; determining the mechanisms of the emerged UV-C tolerance; and performing competition experiments between the iteration strains to quantify fitness tradeoffs resulting from UV-C adaptation.

Aluminum Mirror Coatings for UVOIR Telescope Optics Including the Far UV

Science.gov (United States)

Balasubramanian, Kunjithapatha; Hennessy, John; Raouf, Nasrat; Nikzad, Shouleh; Ayala, Michael; Shaklan, Stuart; Scowen, Paul; Del Hoyo, Javier; Quijada, Manuel

2015-01-01

NASA Cosmic Origins (COR) Program identified the development of high reflectivity mirror coatings for large astronomical telescopes particularly for the far ultra violet (FUV) part of the spectrum as a key technology requiring significant materials research and process development. In this paper we describe the challenges and accomplishments in producing stable high reflectance aluminum mirror coatings with conventional evaporation and advanced Atomic Layer Deposition (ALD) techniques. We present the current status of process development with reflectance of approx. 55 to 80% in the FUV achieved with little or no degradation over a year. Keywords: Large telescope optics, Aluminum mirror, far UV astrophysics, ALD, coating technology development.

CALIBRATING UV STAR FORMATION RATES FOR DWARF GALAXIES FROM STARBIRDS

Energy Technology Data Exchange (ETDEWEB)

McQuinn, Kristen B. W.; Skillman, Evan D.; Mitchell, Noah P. [Minnesota Institute for Astrophysics, University of Minnesota, 116 Church Street, S.E., Minneapolis, MN 55455 (United States); Dolphin, Andrew E., E-mail: kmcquinn@astro.umn.edu [Raytheon Company, 1151 E. Hermans Road, Tucson, AZ 85756 (United States)

2015-08-01

Integrating our knowledge of star formation (SF) traced by observations at different wavelengths is essential for correctly interpreting and comparing SF activity in a variety of systems and environments. This study compares extinction corrected integrated ultraviolet (UV) emission from resolved galaxies with color–magnitude diagram (CMD) based star formation rates (SFRs) derived from resolved stellar populations and CMD fitting techniques in 19 nearby starburst and post-starburst dwarf galaxies. The data sets are from the panchromatic Starburst Irregular Dwarf Survey and include deep legacy GALEX UV imaging, Hubble Space Telescope optical imaging, and Spitzer MIPS imaging. For the majority of the sample, the integrated near-UV fluxes predicted from the CMD-based SFRs—using four different models—agree with the measured, extinction corrected, integrated near-UV fluxes from GALEX images, but the far-UV (FUV) predicted fluxes do not. Furthermore, we find a systematic deviation between the SFRs based on integrated FUV luminosities and existing scaling relations, and the SFRs based on the resolved stellar populations. This offset is not driven by different SF timescales, variations in SFRs, UV attenuation, nor stochastic effects. This first comparison between CMD-based SFRs and an integrated FUV emission SFR indicator suggests that the most likely cause of the discrepancy is the theoretical FUV–SFR calibration from stellar evolutionary libraries and/or stellar atmospheric models. We present an empirical calibration of the FUV-based SFR relation for dwarf galaxies, with uncertainties, which is ∼53% larger than previous relations.

UV Radiation and the Skin

Directory of Open Access Journals (Sweden)

Timothy Scott

2013-06-01

Full Text Available UV radiation (UV is classified as a “complete carcinogen” because it is both a mutagen and a non-specific damaging agent and has properties of both a tumor initiator and a tumor promoter. In environmental abundance, UV is the most important modifiable risk factor for skin cancer and many other environmentally-influenced skin disorders. However, UV also benefits human health by mediating natural synthesis of vitamin D and endorphins in the skin, therefore UV has complex and mixed effects on human health. Nonetheless, excessive exposure to UV carries profound health risks, including atrophy, pigmentary changes, wrinkling and malignancy. UV is epidemiologically and molecularly linked to the three most common types of skin cancer, basal cell carcinoma, squamous cell carcinoma and malignant melanoma, which together affect more than a million Americans annually. Genetic factors also influence risk of UV-mediated skin disease. Polymorphisms of the melanocortin 1 receptor (MC1R gene, in particular, correlate with fairness of skin, UV sensitivity, and enhanced cancer risk. We are interested in developing UV-protective approaches based on a detailed understanding of molecular events that occur after UV exposure, focusing particularly on epidermal melanization and the role of the MC1R in genome maintenance.

Implementation of innovative pulsed xenon ultraviolet (PX-UV environmental cleaning in an acute care hospital

Directory of Open Access Journals (Sweden)

Fornwalt L

2014-01-01

Full Text Available Lori Fornwalt,1 Brad Riddell1,2 1Departments of Infection Prevention and Environmental Services, Trinity Medical Centre, Birmingham, AL, 2Environmental Services, Medical University of South Carolina, Charleston, SC, USA Abstract: It is widely acknowledged that the hospital environment is an important reservoir for many of the pathogenic microbes associated with health care-associated infections (HAIs. Environmental cleaning plays an important role in the prevention and containment of HAIs, in patient safety, and the overall experience of health care facilities. New technologies, such as pulsed xenon ultraviolet (PX-UV light systems are an innovative development for enhanced cleaning and decontamination of hospital environments. A portable PX-UV disinfection device delivers pulsed UV light to destroy microbial pathogens and spores, and can be used in conjunction with manual environmental cleaning. In addition, this technology facilitates thorough disinfection of hospital rooms in 10–15 minutes. The current study was conducted to evaluate whether the introduction of the PX-UV device had a positive impact on patient satisfaction. Satisfaction was measured using the Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS survey. In 2011, prior to the introduction of the PX-UV system, patient HCAHPS scores for cleanliness averaged 75.75%. In the first full quarter after enhanced cleaning of the facility was introduced, this improved to 83%. Overall scores for the hospital rose from 76% (first quarter, 2011 to 87.6% (fourth quarter, 2012. As a result of this improvement, the hospital received 1% of at-risk reimbursement from the inpatient prospective payment system as well as additional funding. Cleanliness of the hospital environment is one of the questions included in the HCAHPS survey and one measure of patient satisfaction. After the introduction of the PX-UV system, the score for cleanliness and the overall rating of the

CUVE - Cubesat UV Experiment: Unveil Venus' UV Absorber with Cubesat UV Mapping Spectrometer

Science.gov (United States)

Cottini, V.; Aslam, S.; D'Aversa, E.; Glaze, L.; Gorius, N.; Hewagama, T.; Ignatiev, N.; Piccioni, G.

2017-09-01

Our Venus mission concept Cubesat UV Experiment (CUVE) is one of ten proposals selected for funding by the NASA PSDS3 Program - Planetary Science Deep Space SmallSat Studies. CUVE concept is to insert a CubeSat spacecraft into a Venusian orbit and perform remote sensing of the UV spectral region using a high spectral resolution point spectrometer to resolve UV molecular bands, observe nightglow, and characterize the unidentified main UV absorber. The UV spectrometer is complemented by an imaging UV camera with multiple bands in the UV absorber main band range for contextual imaging. CUVE Science Objectives are: the nature of the "Unknown" UV-absorber; the abundances and distributions of SO2 and SO at and above Venus's cloud tops and their correlation with the UV absorber; the atmospheric dynamics at the cloud tops, structure of upper clouds and wind measurements from cloud-tracking; the nightglow emissions: NO, CO, O2. This mission will therefore be an excellent platform to study Venus' cloud top atmospheric properties where the UV absorption drives the planet's energy balance. CUVE would complement past, current and future Venus missions with conventional spacecraft, and address critical science questions cost effectively.

uvsI mutants defective in UV mutagenesis define a fourth epistatic group of uvs genes in Aspergillus.

Science.gov (United States)

Chae, S K; Kafer, E

1993-01-01

Three UV-sensitive mutations of A. nidulans, uvsI, uvsJ and uvsA, were tested for epistatic relationships with members of the previously established groups, here called the "UvsF", "UvsC", and "UvsB" groups. uvsI mutants are defective for spontaneous and induced reversion of certain point mutations and differ also for other properties from previously analyzed uvs types. They are very sensitive to the killing effects of UV-light and 4-NQO (4-nitro-quinoline-N-oxide) but not to MMS (methylmethane sulfonate). When double- and single-mutant uvs strains were compared for sensitivity to these three agents, synergistic or additive effects were found for uvsI with all members of the three groups. The uvsI gene may therefore represent a fourth epistatic group, possibly involved in mutagenic repair. On the other hand, uvsJ was clearly epistatic with members of the UvsF group and fitted well into this group also by phenotype. The uvsA gene was tentatively assigned to the UvsC group. uvsA showed epistatic interactions with uvsC in all tests, and like UvsC-group mutants is UV-sensitive mainly in dividing cells. However, the uvsA mutation does not cause the defects in recombination and UV mutagenesis typical for this group.

Evaluation of parameters associated with UV/EB cured clearcoats degradation used in outdoor environment

International Nuclear Information System (INIS)

Ruiz, Carmen Silvia Bentivoglio

2003-01-01

The materials curable by ultraviolet (UV) or electron beam (EB) radiation such as inks, adhesives and coatings are reactive compounds made up of resin, monomer, photoinitiator and additives which undergo polymerization and crosslinking under irradiation producing thermoset products. This technology has been used in a great variety of industrial applications, replacing the conventional curing process in the development of new products. One of the challenging applications has been to design weatherable radiation cured coating which maintain their desirable physical properties and aesthetic appearance. This research reports information about the behavior of four UV and EB curable clear coatings -with or without light stabilizer additives- under accelerated weathering. Thermogravimetry, differential scanning calorimetry, differential photo calorimetry, infrared and ultraviolet spectroscopy and tensile properties were used to evaluate these formulations. Clear coating 50 mum thick films were cured with UV and EB radiation at different doses. The UV curing process was carried out at room temperature using an UV tunnel, with a medium pressure mercury lamp and a transport belt with variable speed. The ultraviolet radiation doses were in the range of 50 to 1500 mJ cm -2 . The EB curing process was performed under N 2 atmosphere, with doses in the range from 1,6 to 300 kGy using the IPEN-CNEN/SP Dynamitron electron beam accelerator with energy of 1.5 MeV. The cure degree was determined by means of the residual reaction heat of the under cured samples obtained from photo-DSC or DSC measurements. The accelerated aging tests were carried out using a Weather-Ometer chamber with exposition times in the range of 100 to 3000 hours. The experimental data obtained from the photo-aged samples were evaluated and correlated to the formulation composition, type of radiation - UV or EB, radiation dose and residence time in the aging chamber. The results have shown that the EB cured films

Complementary UV-Absorption of Mycosporine-like Amino Acids and Scytonemin is Responsible for the UV-Insensitivity of Photosynthesis in Nostoc flagelliforme

Science.gov (United States)

Ferroni, Lorenzo; Klisch, Manfred; Pancaldi, Simonetta; Häder, Donat-Peter

2010-01-01

Mycosporine-like amino acids (MAAs) and scytonemin are UV-screening compounds that have presumably appeared early in the history of life and are widespread in cyanobacteria. Natural colonies of the UV-insensitive Nostoc flagelliforme were found to be especially rich in MAAs (32.1 mg g DW−1), concentrated in the glycan sheath together with scytonemin. MAAs are present in the form of oligosaccharide-linked molecules. Photosystem II activity, measured using PAM fluorescence and oxygen evolution, was used as a most sensitive physiological parameter to analyse the effectiveness of UV-protection. Laboratory experiments were performed under controlled conditions with a simulated solar radiation specifically deprived of UV-wavebands with cut-off filters (295, 305, 320, 345 and 395 nm). The UV-insensitivity of N. flagelliforme was found to cover the whole UV-A (315–400 nm) and UV-B (280–320 nm) range and is almost certainly due to the complementary UV-absorption of MAAs and scytonemin. The experimental approach used is proposed to be suitable for the comparison of the UV-protection ability in organisms that differ in their complement of UV-sunscreen compounds. Furthermore, this study performed with a genuinely terrestrial organism points to the relevance of marine photoprotective compounds for life on Earth, especially for the colonization of terrestrial environments. PMID:20161974

Complementary UV-Absorption of Mycosporine-like Amino Acids and Scytonemin is Responsible for the UV-Insensitivity of Photosynthesis in Nostoc flagelliforme

Directory of Open Access Journals (Sweden)

Donat-Peter Häder

2010-01-01

Full Text Available Mycosporine-like amino acids (MAAs and scytonemin are UV-screening compounds that have presumably appeared early in the history of life and are widespread in cyanobacteria. Natural colonies of the UV-insensitive Nostoc flagelliforme were found to be especially rich in MAAs (32.1 mg g DW-1, concentrated in the glycan sheath together with scytonemin. MAAs are present in the form of oligosaccharide-linked molecules. Photosystem II activity, measured using PAM fluorescence and oxygen evolution, was used as a most sensitive physiological parameter to analyse the effectiveness of UV-protection. Laboratory experiments were performed under controlled conditions with a simulated solar radiation specifically deprived of UV-wavebands with cut-off filters (295, 305, 320, 345 and 395 nm. The UV-insensitivity of N. flagelliforme was found to cover the whole UV-A (315–400 nm and UV-B (280–320 nm range and is almost certainly due to the complementary UV-absorption of MAAs and scytonemin. The experimental approach used is proposed to be suitable for the comparison of the UV-protection ability in organisms that differ in their complement of UV-sunscreen compounds. Furthermore, this study performed with a genuinely terrestrial organism points to the relevance of marine photoprotective compounds for life on Earth, especially for the colonization of terrestrial environments.

[Light protection: principles of UV protection].

Science.gov (United States)

Stege, H; Mang, R

2006-05-01

UV radiation is responsible for the induction of epithelial and melanocytic skin cancer, photoaging, and photodermatoses. UV protection is necessary to prevent damage caused by non-physiologic exposure. UV protection includes not only reduction of sun exposure but also use of sun protective filters, UV protective clothes, DNA repair enzymes, and antioxidant supplementation. Consumers are uncertain about the possibilities and limitations of commercial sun protection measures. Dermatologists must explain protective measures to the general public which continues to believe that UV-tanned skin is healthy. The sunscreen market is a highly competitive but lucrative market. The range of products with different designations and promises makes difficult for both consumers and dermatologists to determine what is sensible UV protection.

UV-induced skin damage

International Nuclear Information System (INIS)

Ichihashi, M.; Ueda, M.; Budiyanto, A.; Bito, T.; Oka, M.; Fukunaga, M.; Tsuru, K.; Horikawa, T.

2003-01-01

Solar radiation induces acute and chronic reactions in human and animal skin. Chronic repeated exposures are the primary cause of benign and malignant skin tumors, including malignant melanoma. Among types of solar radiation, ultraviolet B (290-320 nm) radiation is highly mutagenic and carcinogenic in animal experiments compared to ultraviolet A (320-400 nm) radiation. Epidemiological studies suggest that solar UV radiation is responsible for skin tumor development via gene mutations and immunosuppression, and possibly for photoaging. In this review, recent understanding of DNA damage caused by direct UV radiation and by indirect stress via reactive oxygen species (ROS) and DNA repair mechanisms, particularly nucleotide excision repair of human cells, are discussed. In addition, mutations induced by solar UV radiation in p53, ras and patched genes of non-melanoma skin cancer cells, and the role of ROS as both a promoter in UV-carcinogenesis and an inducer of UV-apoptosis, are described based primarily on the findings reported during the last decade. Furthermore, the effect of UV on immunological reaction in the skin is discussed. Finally, possible prevention of UV-induced skin cancer by feeding or topical use of antioxidants, such as polyphenols, vitamin C, and vitamin E, is discussed

Antiradiation UV Vaccine: UV Radiation, Biological effects, lesions and medical management - immune-therapy and immune-protection.

Science.gov (United States)

Popov, Dmitri; Jones, Jeffrey; Maliev, Slava

Key Words: Ultraviolet radiation,Standard Erythema Dose(SED), Minimal Erythema Dose(MED), Sun Burns, Solar Dermatitis, Sun Burned Disease, DNA Damage,Cell Damage, Antiradiation UV Vaccine, Immune-Prophylaxis of Sun Burned Diseases, Immune-Prophylaxis of Sun Burns, Immune-Therapy of Sun-Burned Disease and Sun Burns,Basal Cell Carcinoma (BCC), Squamous Cell Carcinoma (SCC), Toxic Epidermal Necrolysis(TEN). Introduction: High doses of UV generated by solar source and artificial sources create an exposure of mammals and other species which can lead to ultraviolet(UV)radiation- associated disease (including erythema, epilation, keratitis, etc.). UV radiation belongs to the non-ionizing part of the electromagnetic spectrum and ranges between 100 nm and 400 nm with 100 nm having been chosen arbitrarily as the boundary between non-ionizing and ionizing radiation, however EMR is a spectrum and UV can produce molecular ionization. UV radiation is conventionally categorized into 3 areas: UV-A (>315-400 nm),UV-B (>280-315 nm)and UV-C (>100-280 nm) [IARC,Working Group Reports,2005] An important consequence of stratospheric ozone depletion is the increased transmission of solar ultraviolet (UV)radiation to the Earth's lower atmosphere and surface. Stratospheric ozone levels have been falling, in certain areas, for the past several decades, so current surface ultraviolet-B (UV-B) radiation levels are thought to be close to their modern day maximum. [S.Madronich et al.1998] Overexposure of ultraviolet radiation a major cause of skin cancer including basal cell carcinoma (BCC), squamous cell carcinoma (SCC) { collectively referred to as “non-melanoma" skin cancer (NMSC) and melanoma as well, with skin cancers being the most common cancer in North America. [Armstrong et al. 1993, Gallagher et al. 2005] Methods and Experimental Design: Our experiments and testing of a novel UV “Antiradiation Vaccine” have employed a wide variety of laboratory animals which include : Chinchilla

Photostability of cosmetic UV filters on mammalian skin under UV exposure.

Science.gov (United States)

Stiefel, Constanze; Schwack, Wolfgang; Nguyen, Yen-Thi Hai

2015-01-01

Previous studies showed that the common UV filter substances benzophenone-3 (BP-3), butyl methoxydibenzoylmethane (BM-DBM), octocrylene (OCR), ethylhexyl methoxycinnamate (EHMC), ethylhexyl salicylate (EHS) and ethylhexyl triazone (EHT) were able to react with amino side chains of different proteins in vitro. To transfer the results to mammalian skin conditions, sunscreen products were applied on both prepared fresh porcine skin and glass plates, followed by UV irradiation and the determination of depletion of the respective UV filters. Significantly lower recoveries of the UV filters extracted from skin samples than from glass plates indicated the additional reaction of the UV filters with skin constituents, when proteins will be the most important reactants. Among the products tested, BP-3 showed the greatest differences in recoveries between glass and skin samples of about 13% and 24% after 2 and 4 h of irradiation, respectively, followed by EHS > BM-DBM > OCR > EHMC > EHT. The obtained results raise the question, whether the common in vitro evaluations of sunscreens, using inert substrate materials like roughened quartz or polymethyl methacrylate (PMMA) plates are really suitable to fully replace in vivo methods, as they cannot include skin-typical reactions. © 2014 The American Society of Photobiology.

Direct UV-writing of waveguides

DEFF Research Database (Denmark)

Færch, Kjartan Ullitz

2003-01-01

induced refractive index change of more than 10-2 have been obtained. New insight, with respect to understanding the UV induced index change obtained by direct UV writing, has been provided, through experiments conducted with such high-pressure loaded germanosilica samples. This include measurements...

The World Space Observatory Ultraviolet (WSO-UV), as a bridge to future UV astronomy

Science.gov (United States)

Shustov, B.; Gómez de Castro, A. I.; Sachkov, M.; Vallejo, J. C.; Marcos-Arenal, P.; Kanev, E.; Savanov, I.; Shugarov, A.; Sichevskii, S.

2018-04-01

Ultraviolet (UV) astronomy is a vital branch of space astronomy. Many dozens of short-term UV-experiments in space, as well as long-term observatories, have brought a very important knowledge on the physics and chemistry of the Universe during the last decades. Unfortunately, no large UV-observatories are planned to be launched by most of space agencies in the coming 10-15 years. Conversely, the large UVOIR observatories of the future will appear not earlier than in 2030s. This paper briefly describes the projects that have been proposed by various groups. We conclude that the World Space Observatory-Ultraviolet (WSO-UV) will be the only 2-m class UV telescope with capabilities similar to those of the HST for the next decade. The WSO-UV has been described in detail in previous publications, and this paper updates the main characteristics of its instruments and the current state of the whole project. It also addresses the major science topics that have been included in the core program of the WSO-UV, making this core program very relevant to the current state of the UV-astronomy. Finally, we also present here the ground segment architecture that will implement this program.

Benchmark studies of UV-vis spectra simulation for cinnamates with UV filter profile.

Science.gov (United States)

Garcia, Ricardo D'A; Maltarollo, Vinícius G; Honório, Káthia M; Trossini, Gustavo H G

2015-06-01

Skin cancer is a serious public health problem worldwide, being incident over all five continents and affecting an increasing number of people. As sunscreens are considered an important preventive measure, studies to develop better and safer sunscreens are crucial. Cinnamates are UVB filters with good efficiency and cost-benefit, therefore, their study could lead to the development of new UV filters. A benchmark to define the most suitable density functional theory (DFT) functional to predict UV-vis spectra for ethylhexyl methoxycinnamate was performed. Time-dependent DFT (TD-DFT) calculations were then carried out [B3LYP/6-311 + G(d,p) and B3P86/6-311 + G(d,p) in methanol environment] for seven cinammete derivatives implemented in the Gaussian 03 package. All DFT/TD-DFT simulations were performed after a conformational search with the Monte-Carlo method and MMFF94 force field. B3LYP and B3P86 functionals were better at reproducing closely the experimental spectra of ethylhexyl methoxycinnamate. Calculations of seven cinnamates showed a λmax of around 310 nm, corroborating literature reports. It was observed that the energy for the main electronic transition was around 3.95 eV and could be explained by electron delocalization on the aromatic ring and ester group, which is important to UV absorption. The methodology employed proved to be suitable for determination of the UV spectra of cinnamates and could be used as a tool for the development of novel UV filters.

In the shadow of the Cosmetic Directive--inconsistencies in EU environmental hazard classification requirements for UV-filters.

Science.gov (United States)

Sobek, A; Bejgarn, S; Rudén, C; Molander, L; Breitholtz, M

2013-09-01

UV-filters are chemicals with potentially environmental hazardous properties. In the European Union (EU), UV-filters contained in sunscreen products are currently regulated by the Cosmetic Directive (from July 2013 by the Cosmetic Products Regulation). Environmental hazard classifications according to the regulation on classification, labelling and packaging of substances and mixtures (CLP) must be determined for UV-filters contained in industrial chemical products, whereas UV-filters contained in sunscreens are exempted from CLP. In this study we determined the potential environmental hazard classifications of UV-filters and sunscreen products if the CLP regulation was to be required for cosmetic products. Two sunscreen products were evaluated in accordance with the aquatic environmental hazard criteria for mixtures. The results highlight that the inconsistencies in the current EU regulation of UV filters hamper the risk management of environmental hazards of UV filters used in cosmetic products. Almost 50% of the investigated UV-filters approved for use in cosmetic products on the European market according to the current Cosmetic Directive were identified to meet the CLP classification as being hazardous to the aquatic environment. Assuming a worst-case scenario, the two examined sunscreens could both be classified as hazardous to the aquatic environment with long-lasting effects according to CLP classification criteria. Hence, if the CLP regulation was applicable to sunscreen products, both brands could potentially be labelled with the environmental hazard pictogram and associated hazard and precautionary statements. Including cosmetic products, and thereby sunscreens, in the CLP regulation would contribute to a more harmonized and transparent regulation of potentially hazardous substances on the EU market. Copyright © 2013 Elsevier B.V. All rights reserved.

The UV Survey Mission Concept, CETUS

Science.gov (United States)

Heap, Sara; and the CETUS Team

2018-01-01

In March 2017, NASA selected CETUS for study of a Probe-class mission concept. W. Danchi is the CETUS PI, and S. Heap is the Science PI. CETUS is primarily a UV survey telescope to complement survey telescopes of the 2020’s including E-ROSITA, Subaru Hyper Suprime Cam and Prime-Focus Spectrograph, WFIRST, and the Square Kilometer Array. CETUS comprises a 1.5-m wide-field telescope and three science instruments: a wide-field (1045” on a side) far-UV and near-UV camera; a similarly wide-field near-UV multi-object spectrograph utilizing a next-generation micro-shutter array; and a single-object spectrograph with options of spectral region (far-UV or near-UV) and spectral resolving power (2,000 or 40,000). The survey instruments will operate simultaneously thereby producing wide-field images in the near-UV and far-UV and a spectrogram containing near-UV spectra of up to 100 sources free of spectral overlap and astronomical background. ln concert with other survey telescopes, CETUS will focus on understanding galaxy evolution at cosmic noon (z~1-2).

Malbec grape (Vitis vinifera L.) responses to the environment: Berry phenolics as influenced by solar UV-B, water deficit and sprayed abscisic acid.

Science.gov (United States)

Alonso, Rodrigo; Berli, Federico J; Fontana, Ariel; Piccoli, Patricia; Bottini, Rubén

2016-12-01

High-altitude vineyards receive elevated solar ultraviolet-B (UV-B) levels so producing high quality berries for winemaking because of induction in the synthesis of phenolic compounds. Water deficit (D) after veraison, is a commonly used tool to regulate berry polyphenols concentration in red wine cultivars. Abscisic acid (ABA) plays a crucial role in the acclimation to environmental factors/signals (including UV-B and D). The aim of the present study was to evaluate independent and interactive effects of high-altitude solar UV-B, moderate water deficit and ABA applications on Vitis vinifera cv. Malbec berries. The experiment was conducted during two growing seasons with two treatments of UV-B (+UV-B and -UV-B), watering (+D and -D) and ABA (+ABA and -ABA), in a factorial design. Berry fresh weight, sugar content, fruit yield, phenolic compounds profile and antioxidant capacity (ORAC) were analyzed at harvest. Previous incidence of high UV-B prevented deleterious effects of water deficit, i.e. berry weight reduction and diminution of sugar accumulation. High UV-B increased total phenols (mainly astilbin, quercetin and kaempferol) and ORAC, irrespectively of the combination with other factors. Fruit yield was reduced by combining water deficit and high UV-B or water deficit and ABA. Two applications of ABA were enough to induced biochemical changes increasing total anthocyanins, especially those with higher antioxidant capacity. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Hybrid AlGaN-SiC Avalanche Photodiode for Deep-UV Photon Detection

Science.gov (United States)

Aslam, Shahid; Herrero, Federico A.; Sigwarth, John; Goldsman, Neil; Akturk, Akin

2010-01-01

The proposed device is capable of counting ultraviolet (UV) photons, is compatible for inclusion into space instruments, and has applications as deep- UV detectors for calibration systems, curing systems, and crack detection. The device is based on a Separate Absorption and Charge Multiplication (SACM) structure. It is based on aluminum gallium nitride (AlGaN) absorber on a silicon carbide APD (avalanche photodiode). The AlGaN layer absorbs incident UV photons and injects photogenerated carriers into an underlying SiC APD that is operated in Geiger mode and provides current multiplication via avalanche breakdown. The solid-state detector is capable of sensing 100-to-365-nanometer wavelength radiation at a flux level as low as 6 photons/pixel/s. Advantages include, visible-light blindness, operation in harsh environments (e.g., high temperatures), deep-UV detection response, high gain, and Geiger mode operation at low voltage. Furthermore, the device can also be designed in array formats, e.g., linear arrays or 2D arrays (micropixels inside a superpixel).

UV Radiation in an Urban Canyon in Southeast Queensland

Science.gov (United States)

McKinley, A. R.; Moore, M. R.; Kimlin, M. G.

2006-12-01

Ultraviolet radiation (UV) has the possibility to both harm and to benefit human beings when unprotected exposure occurs. After receiving small amounts of UV our bodies begin to synthesise vitamin D, which is essential for maintaining healthy bones, however excessive UV exposure can result in a variety of damaging outcomes ranging from sunburn to skin cancer and cataracts. For this reason it is very important to understand the different environments in which people encounter UV so as to better prepare the public to make smart and healthy sun exposure decisions. Each day more and more people are moving into large cities around the world and spending their time inside the urban canyon, however UV measurements are generally taken at scientific stations in open areas or on top of tall buildings, meaning that at times the environmental characteristics measured may not accurately represent those found at street-level in these highly urbanized areas. Urban canyons are home to both very tall buildings and tropospheric air pollution, each of which reduces the amount of UV reaching street-level. This study measured the varying difference between UV measurements taken at street-level and at a standard UV monitoring site on top of a building outside of the urban canyon. Investigation was conducted in the central business district (CBD) of Brisbane, Australia, which models the CBDs of large cities around the world in that it boasts a great number of tall buildings, including many skyscrapers. Data was collected under clear sky conditions at five different street-level sites in the CBD (on either side of two streets running perpendicular to one another (four sites) and in a public square) and then compared to that obtained on the same day at the Queensland University of Technology's Australian Sun and Health Research Laboratory (ASHRL), which is located 2.5 kilometres outside Brisbane's CBD. Minimum erythemal dose (MED) data was collected at each location and it was found that

UV spectroscopy including ISM line absorption: of the exciting star of Abell 35

Science.gov (United States)

Ziegler, M.; Rauch, T.; Werner, K.; Kruk, J. W.

Reliable spectral analysis that is based on high-resolution UV observations requires an adequate, simultaneous modeling of the interstellar line absorption and reddening. In the case of the central star of the planetary nebula Abell 35, BD-22 3467, we demonstrate our current standard spectral-analysis method that is based on the Tübingen NLTE Model-Atmosphere Package (TMAP). We present an on- going spectral analysis of FUSE and HST/STIS observations of BD-22 3467.

The influence of enhanced UV-B radiation on Batrachium trichophyllum and Potamogeton alpinus -- aquatic macrophytes with amphibious character.

Science.gov (United States)

Germ, Mateja; Mazej, Zdenka; Gaberscik, Alenka; Häder, Donat P

2002-02-01

The responses of two amphibious species, Batrachium trichophyllum and Potamogeton alpinus to different UV-B environments were studied. Plant material from natural environments, as well as from outdoor treatments was examined. In long-term outdoor experiments plants were grown under three different levels of UV-B radiation: reduced and ambient UV-B levels, and a UV-B level simulating 17% ozone depletion. The following parameters were monitored: contents of total methanol soluble UV-absorbing compounds and chlorophyll a, terminal electron transport system (ETS) activity and optimal and effective quantum yield of photosystem II. No effect of the different UV-B levels on the measured parameters was observed. The amount of UV-B absorbing compounds seems to be saturated, since no differences were observed between treatments and no increase was found in peak season, when natural UV-B levels were the highest. Physiological measurements revealed no harmful effects; neither on potential and actual photochemical efficiency, nor on terminal ETS activity. The contents of UV-B absorbing compounds were examined also in plant material sampled in low and high altitude environments during the growth season. Both species exhibited no seasonal dynamics of production of UV-absorbing compounds. The contents were variable and showed no significant differences between high and low altitude populations.

Effects of environmental and artificial UV-B radiation on freshwater prawn Macrobrachium olfersi embryos

Energy Technology Data Exchange (ETDEWEB)

Nazari, Evelise Maria [Programa de Pos-Graduacao em Ciencias Morfologicas, Instituto de Ciencias Biomedicas, Universidade Federal do Rio de Janeiro, 21949-902 Rio de Janeiro, RJ (Brazil); Universidade Federal de Santa Catarina, Departamento de Biologia Celular, Embriologia e Genetica, Campus Universitario, 88040-900 Florianopolis, SC (Brazil); Ammar, Dib [Universidade do Oeste de Santa Catarina, Departamento de Biologia, Campus Universitario, 89600-000 Joacaba, SC (Brazil); Bem, Andreza Fabro de; Latini, Alexandra [Universidade Federal de Santa Catarina, Departamento de Bioquimica, Campus Universitario, 88040-900 Florianopolis, SC (Brazil); Mueller, Yara Maria Rauh [Universidade Federal de Santa Catarina, Departamento de Biologia Celular, Embriologia e Genetica, Campus Universitario, 88040-900 Florianopolis, SC (Brazil); Allodi, Silvana, E-mail: sallodi@histo.ufrj.br [Programa de Pos-Graduacao em Ciencias Morfologicas, Instituto de Ciencias Biomedicas, Universidade Federal do Rio de Janeiro, 21949-902 Rio de Janeiro, RJ (Brazil)

2010-06-01

The recent decrease of the stratospheric ozone has resulted in an increase of ultraviolet-B (UV-B) radiation reaching the Earth's surface. In freshwater ecosystems with transparent water, UV-B rays easily penetrate and potentially cause harmful effects to organisms. In this study, embryos of the prawn Macrobrachium olfersi were used to evaluate the impact of UV-B rays in freshwater environments. We observed three groups of embryos: the first was to assess whether UV-B radiation produced morphological defects and/or biochemical impairments in the laboratory. The second was to check whether embryos with the same impairments as those observed in the laboratory were found in their environment, under natural solar radiation. The third group was the non-irradiated control. The embryos irradiated with 310 mW cm{sup -2} UV-B for 30 min showed morphological alterations similar to those observed in embryos from the environmental control group. The most important effects of the UV-B radiation observed in M. olfersi embryos were morphological (1.2% of the total number of embryos from the environment and 2.8% of the total number of irradiated embryos), pigmentation changes in the eyes (78.0% of the total number of embryos from the environment and 98.9% of the total number of irradiated embryos), and disruption of the chromatophores (46.9% of the total number of embryos from the environment and 95.5% of the total number of irradiated embryos). We also observed an increase in egg volume, which was accompanied by a significant increase in water content in UV-B irradiated groups when compared with aquaria control embryos. In addition, a significant decrease in the mitotic index in eggs exposed to UV-B radiation was detected (0.17 for the embryos from the aquaria control, 0.10 for the embryos of the environmental control, and 0.04 for the irradiated groups). The low levels of NPSH and high levels of TBARS indicated that UV-B rays directly compromised the antioxidant function of

Effects of environmental and artificial UV-B radiation on freshwater prawn Macrobrachium olfersi embryos

International Nuclear Information System (INIS)

Nazari, Evelise Maria; Ammar, Dib; Bem, Andreza Fabro de; Latini, Alexandra; Mueller, Yara Maria Rauh; Allodi, Silvana

2010-01-01

The recent decrease of the stratospheric ozone has resulted in an increase of ultraviolet-B (UV-B) radiation reaching the Earth's surface. In freshwater ecosystems with transparent water, UV-B rays easily penetrate and potentially cause harmful effects to organisms. In this study, embryos of the prawn Macrobrachium olfersi were used to evaluate the impact of UV-B rays in freshwater environments. We observed three groups of embryos: the first was to assess whether UV-B radiation produced morphological defects and/or biochemical impairments in the laboratory. The second was to check whether embryos with the same impairments as those observed in the laboratory were found in their environment, under natural solar radiation. The third group was the non-irradiated control. The embryos irradiated with 310 mW cm -2 UV-B for 30 min showed morphological alterations similar to those observed in embryos from the environmental control group. The most important effects of the UV-B radiation observed in M. olfersi embryos were morphological (1.2% of the total number of embryos from the environment and 2.8% of the total number of irradiated embryos), pigmentation changes in the eyes (78.0% of the total number of embryos from the environment and 98.9% of the total number of irradiated embryos), and disruption of the chromatophores (46.9% of the total number of embryos from the environment and 95.5% of the total number of irradiated embryos). We also observed an increase in egg volume, which was accompanied by a significant increase in water content in UV-B irradiated groups when compared with aquaria control embryos. In addition, a significant decrease in the mitotic index in eggs exposed to UV-B radiation was detected (0.17 for the embryos from the aquaria control, 0.10 for the embryos of the environmental control, and 0.04 for the irradiated groups). The low levels of NPSH and high levels of TBARS indicated that UV-B rays directly compromised the antioxidant function of the

LADEE UVS Observations of Atoms and Dust in the Lunar Tail

Science.gov (United States)

Wooden, Diane H.; Colaprete, Anthony; Cook, Amanda M.; Shirley, Mark H.; Vargo, Kara E.; Elphic, Richard C.; Stubbs, Timothy J.; Glenar, David A.

2014-01-01

The Lunar Atmosphere and Dust Environment Explorer (LADEE) was a lunar orbiter launched in September 2013 that investigated the composition and temporal variation of the tenuous lunar exosphere and dust environment. A major goal of the mission was to characterize the dust exosphere prior to future lunar exploration activities, which may alter the lunar environment. The Ultraviolet/Visible Spectrometer (UVS) onboard LADEE addresses this goal, utilizing two sets of optics: a limbviewing telescope, and a solar-viewing telescope. We report on spectroscopic (approximately 280 - 820 nm) observations viewing down the lunar wake or along the 'lunar tail' from lunar orbit. Prior groundbased studies have observed the emission from neutral sodium atoms extended along the lunar tail, so often this region is referred to as the lunar sodium tail. UVS measurements were made on the dark side of the moon, with the UVS limb-viewing telescope pointed outward in the direction of the Moon's wake (almost anti-sun), during different lunar phases. These UVS observation activities sample a long column and allow the characterization of scattered light from dust and emission lines from atoms in the lunar tail. Observations in this UVS configuration show the largest excess of scattered blue light in our data set, indicative of the presence of small dust grains in the tail. Once lofted, nanoparticles may become charged and picked up by the solar wind, similar to the phenomena witnessed above Enceladus's northern hemisphere or by the STEREO/WAVES instrument while close to Earth's orbit. The UVS data show that small dust grains as well as atoms become entrained in the lunar tail.

Development of a method for the characterization and operation of UV-LED for water treatment.

Science.gov (United States)

Kheyrandish, Ataollah; Mohseni, Madjid; Taghipour, Fariborz

2017-10-01

Tremendous improvements in semiconductor technology have made ultraviolet light-emitting diodes (UV-LEDs) a viable alternative to conventional UV sources for water treatment. A robust and validated experimental protocol for studying the kinetics of microorganism inactivation is key to the further development of UV-LEDs for water treatment. This study proposes a protocol to operate UV-LEDs and control their output as a polychromatic radiation source. In order to systematically develop this protocol, the results of spectral power distribution, radiation profile, and radiant power measurements of a variety of UV-LEDs are presented. A wide range of UV-LEDs was selected for this study, covering various UVA, UVB, and UVC wavelengths, viewing angles from 3.5° to 135°, and a variety of output powers. The effects of operational conditions and measurement techniques were investigated on these UV-LEDs using a specially designed and fabricated setup. Operating conditions, such as the UV-LED electrical current and solder temperature, were found to significantly affect the power and peak wavelength output. The measurement techniques and equipment, including the detector size, detector distance from the UV-LED, and potential reflection from the environment, were shown to influence the results for many of the UV-LEDs. The results obtained from these studies were analyzed and applied to the development of a protocol for UV-LED characterization. This protocol is presented as a guideline that allows the operation and control of UV-LEDs in any structure, as well as accurately measuring the UV-LED output. Such information is essential for performing a reliable UV-LED assessment for the inactivation of microorganisms and for obtaining precise kinetic data. Copyright © 2017 Elsevier Ltd. All rights reserved.

Pectins, ROS homeostasis and UV-B responses in plant roots.

Science.gov (United States)

Yokawa, Ken; Baluška, František

2015-04-01

Light from the sun contains far-red, visible and ultra violet (UV) wavelength regions. Almost all plant species have been evolved under the light environment. Interestingly, several photoreceptors, expressing both in shoots and roots, process the light information during the plant life cycle. Surprisingly, Arabidopsis root apices express besides the UVR8 UV-B receptor, also root-specific UV-B sensing proteins RUS1 and RUS2 linked to the polar cell-cell transport of auxin. In this mini-review, we focus on reactive oxygen species (ROS) signaling and possible roles of pectins internalized via endocytic vesicle recycling system in the root-specific UV-B perception and ROS homeostasis. Copyright © 2014 Elsevier Ltd. All rights reserved.

UV-B Radiation Contributes to Amphibian Population Declines

Science.gov (United States)

Blaustein, Andrew

2007-05-01

UV-B (280-315 nm) radiation is the most significant biologically damaging radiation at the terrestrial surface. At the organismal level, UV-B radiation can slow growth rates, cause immune dysfunction and result in sublethal damage. UV-B radiation can lead to mutations and cell death. Over evolutionary time, UV radiation has been an important stressor on living organisms. Natural events, including impacts from comets and asteroids, volcanic activity, supernova explosions and solar flares, can cause large-scale ozone depletion with accompanying increases in UV radiation. However, these natural events are transient. Moreover, the amount of ozone damage due to natural events depends upon a number of variables, including the magnitude of the event. This is different from modern-day human-induced production of chlorofluorocarbons (CFCs) and other chemicals that deplete stratospheric ozone continuously, resulting in long-term increases in UV-B radiation at the surface of the earth. We will briefly review the effects of UV-B exposure in one group of aquatic organisms_amphibians. UV-B has been implicated as a possible factor contributing to global declines and range reductions in amphibian populations.

Effect of enhanced UV-B radiation on motile microorganisms

International Nuclear Information System (INIS)

Haeder, D.P.

1985-02-01

The effect of slightly increased UV-B radiation was studied in four taxonomically very different microorganisms: the gliding prokaryotic cyanobacterium, Phormidium, the unicellular green alga Cosmarium, the flagellate Euglena and the cellular slime mold Dictyostelium. UV-B doses which can be expected as a result of a slight decrease of the protective ozone layer in the stratosphere, do not kill or damage the microorganisms visibly. However, such UV-B doses impair the development, motility and photoorientation of these organisms. Due to the inhibition of these physiological important parameters the organisms cannot respond adequately to the changing factors in their environment, which prevents the survival of the populations. (orig.) [de

Transformations of dissolved organic matter induced by UV photolysis, Hydroxyl radicals, chlorine radicals, and sulfate radicals in aqueous-phase UV-Based advanced oxidation processes.

Science.gov (United States)

Varanasi, Lathika; Coscarelli, Erica; Khaksari, Maryam; Mazzoleni, Lynn R; Minakata, Daisuke

2018-05-15

Considering the increasing identification of trace organic contaminants in natural aquatic environments, the removal of trace organic contaminants from water or wastewater discharge is an urgent task. Ultraviolet (UV) and UV-based advanced oxidation processes (AOPs), such as UV/hydrogen peroxide (UV/H 2 O 2 ), UV/free chlorine and UV/persulfate, are attractive and promising approaches for the removal of these contaminants due to the high reactivity of active radical species produced in these UV-AOPs with a wide variety of organic contaminants. However, the removal efficiency of trace contaminants is greatly affected by the presence of background dissolved organic matter (DOM). In this study, we use ultrahigh resolution mass spectrometry to evaluate the transformation of a standard Suwanee River fulvic acid DOM isolate in UV photolysis and UV-AOPs. The use of probe compounds allows for the determination of the steady-state concentrations of active radical species in each UV-AOP. The changes in the H/C and O/C elemental ratios, double bond equivalents, and the low-molecular-weight transformation product concentrations of organic acids reveal that different DOM transformation patterns are induced by each UV-AOP. By comparison with the known reactivities of each radical species with specific organic compounds, we mechanistically and systematically elucidate the molecular-level DOM transformation pathways induced by hydroxyl, chlorine, and sulfate radicals in UV-AOPs. We find that there is a distinct transformation in the aliphatic components of DOM due to HO• in UV/H 2 O 2 and UV/free chlorine. Cl• induced transformation of olefinic species is also observed in the UV/free chlorine system. Transformation of aromatic and olefinic moieties by SO 4 •- are the predominant pathways in the UV/persulfate system. Copyright © 2018 Elsevier Ltd. All rights reserved.

Detecting Kerogen as a Biosignature Using Colocated UV Time-Gated Raman and Fluorescence Spectroscopy.

Science.gov (United States)

Shkolyar, Svetlana; Eshelman, Evan J; Farmer, Jack D; Hamilton, David; Daly, Michael G; Youngbull, Cody

2018-04-01

The Mars 2020 mission will analyze samples in situ and identify any that could have preserved biosignatures in ancient habitable environments for later return to Earth. Highest priority targeted samples include aqueously formed sedimentary lithologies. On Earth, such lithologies can contain fossil biosignatures as aromatic carbon (kerogen). In this study, we analyzed nonextracted kerogen in a diverse suite of natural, complex samples using colocated UV excitation (266 nm) time-gated (UV-TG) Raman and laser-induced fluorescence spectroscopies. We interrogated kerogen and its host matrix in samples to (1) explore the capabilities of UV-TG Raman and fluorescence spectroscopies for detecting kerogen in high-priority targets in the search for possible biosignatures on Mars; (2) assess the effectiveness of time gating and UV laser wavelength in reducing fluorescence in Raman spectra; and (3) identify sample-specific issues that could challenge rover-based identifications of kerogen using UV-TG Raman spectroscopy. We found that ungated UV Raman spectroscopy is suited to identify diagnostic kerogen Raman bands without interfering fluorescence and that UV fluorescence spectroscopy is suited to identify kerogen. These results highlight the value of combining colocated Raman and fluorescence spectroscopies, similar to those obtainable by SHERLOC on Mars 2020, to strengthen the confidence of kerogen detection as a potential biosignature in complex natural samples. Key Words: Raman spectroscopy-Laser-induced fluorescence spectroscopy-Mars Sample Return-Mars 2020 mission-Kerogen-Biosignatures. Astrobiology 18, 431-453.

Interactive Effects of Temperature and UV Radiation on Photosynthesis of Chlorella Strains from Polar, Temperate and Tropical Environments: Differential Impacts on Damage and Repair

Science.gov (United States)

Wong, Chiew-Yen; Teoh, Ming-Li; Phang, Siew-Moi; Lim, Phaik-Eem; Beardall, John

2015-01-01

Global warming and ozone depletion, and the resulting increase of ultraviolet radiation (UVR), have far-reaching impacts on biota, especially affecting the algae that form the basis of the food webs in aquatic ecosystems. The aim of the present study was to investigate the interactive effects of temperature and UVR by comparing the photosynthetic responses of similar taxa of Chlorella from Antarctic (Chlorella UMACC 237), temperate (Chlorella vulgaris UMACC 248) and tropical (Chlorella vulgaris UMACC 001) environments. The cultures were exposed to three different treatments: photosynthetically active radiation (PAR; 400–700 nm), PAR plus ultraviolet-A (320–400 nm) radiation (PAR + UV-A) and PAR plus UV-A and ultraviolet-B (280–320 nm) radiation (PAR + UV-A + UV-B) for one hour in incubators set at different temperatures. The Antarctic Chlorella was exposed to 4, 14 and 20°C. The temperate Chlorella was exposed to 11, 18 and 25°C while the tropical Chlorella was exposed to 24, 28 and 30°C. A pulse-amplitude modulated (PAM) fluorometer was used to assess the photosynthetic response of microalgae. Parameters such as the photoadaptive index (Ek) and light harvesting efficiency (α) were determined from rapid light curves. The damage (k) and repair (r) rates were calculated from the decrease in ΦPSIIeff over time during exposure response curves where cells were exposed to the various combinations of PAR and UVR, and fitting the data to the Kok model. The results showed that UV-A caused much lower inhibition than UV-B in photosynthesis in all Chlorella isolates. The three isolates of Chlorella from different regions showed different trends in their photosynthesis responses under the combined effects of UVR (PAR + UV-A + UV-B) and temperature. In accordance with the noted strain-specific characteristics, we can conclude that the repair (r) mechanisms at higher temperatures were not sufficient to overcome damage caused by UVR in the Antarctic Chlorella strain

Interactive Effects of Temperature and UV Radiation on Photosynthesis of Chlorella Strains from Polar, Temperate and Tropical Environments: Differential Impacts on Damage and Repair.

Directory of Open Access Journals (Sweden)

Chiew-Yen Wong

Full Text Available Global warming and ozone depletion, and the resulting increase of ultraviolet radiation (UVR, have far-reaching impacts on biota, especially affecting the algae that form the basis of the food webs in aquatic ecosystems. The aim of the present study was to investigate the interactive effects of temperature and UVR by comparing the photosynthetic responses of similar taxa of Chlorella from Antarctic (Chlorella UMACC 237, temperate (Chlorella vulgaris UMACC 248 and tropical (Chlorella vulgaris UMACC 001 environments. The cultures were exposed to three different treatments: photosynthetically active radiation (PAR; 400-700 nm, PAR plus ultraviolet-A (320-400 nm radiation (PAR + UV-A and PAR plus UV-A and ultraviolet-B (280-320 nm radiation (PAR + UV-A + UV-B for one hour in incubators set at different temperatures. The Antarctic Chlorella was exposed to 4, 14 and 20°C. The temperate Chlorella was exposed to 11, 18 and 25°C while the tropical Chlorella was exposed to 24, 28 and 30°C. A pulse-amplitude modulated (PAM fluorometer was used to assess the photosynthetic response of microalgae. Parameters such as the photoadaptive index (Ek and light harvesting efficiency (α were determined from rapid light curves. The damage (k and repair (r rates were calculated from the decrease in ΦPSIIeff over time during exposure response curves where cells were exposed to the various combinations of PAR and UVR, and fitting the data to the Kok model. The results showed that UV-A caused much lower inhibition than UV-B in photosynthesis in all Chlorella isolates. The three isolates of Chlorella from different regions showed different trends in their photosynthesis responses under the combined effects of UVR (PAR + UV-A + UV-B and temperature. In accordance with the noted strain-specific characteristics, we can conclude that the repair (r mechanisms at higher temperatures were not sufficient to overcome damage caused by UVR in the Antarctic Chlorella strain

Simulation and comparative study on the oxidation kinetics of atrazine by UV/H₂O₂, UV/HSO₅⁻ and UV/S₂O₈²⁻.

Science.gov (United States)

Luo, Congwei; Ma, Jun; Jiang, Jin; Liu, Yongze; Song, Yang; Yang, Yi; Guan, Yinghong; Wu, Daoji

2015-09-01

This study comparatively investigated atrazine (ATZ) degradation by irradiation at the wavelength of 254 nm in the presence of peroxides including hydrogen peroxide (H2O2), peroxymonosulfate (HSO5(-)), and persulfate (S2O8(2-)) at various initial ATZ concentrations and oxidant dosages. The effects of water matrix, such as carbonate/bicarbonate (HCO3(-)/CO3(2-)), chloride ions (Cl(-)), and natural organic matter (NOM), were evaluated on these three advanced oxidation processes. A simple steady-state kinetic model was developed based on the initial rates of ATZ destruction, which could well describe the apparent pseudo-first-order rate constants (k(app), s(-1)) of ATZ degradation in these three processes. The specific roles of reactive species (i.e., HO·, SO4(-·), CO3(-·), and Cl2(-·)) under various experimental conditions were quantitatively evaluated based on their steady-state concentrations obtained from this model. Modeling results showed that the steady-state concentrations of HO· and SO4(-·) decreased with the increase of CO3(2-)/HCO3(-) concentration, and the relative contribution of HO· to ATZ degradation significantly decreased in UV/H2O2 and UV/HSO5(-) systems. On the other hand, the scavenging effect of HCO3(-)/CO3(2-) on the relative contribution of SO4(-·) to ATZ degradation was lower than that on HO·. The presence of Cl(-) (0.5-10 mM) significantly scavenged SO4(-·) but had slightly scavenging effect on HO· at the present experimental pH, resulting in greater decrease of k(app) in the UV/S2O8(2-) than UV/H2O2 and UV/HSO5(-) systems. Higher levels of Cl2(-·) were generated in the UV/S2O8(2-) than those in the UV/H2O2 and UV/HSO5(-) systems at the same Cl(-) concentrations. NOM significantly decreased k(app) due to its effects of competitive UV absorption and radical scavenging with the latter one being dominant. These results improve the understanding of the effects of water constituents for ATZ degradation in the UV-based oxidation

High speed micromachining with high power UV laser

Science.gov (United States)

Patel, Rajesh S.; Bovatsek, James M.

2013-03-01

Increasing demand for creating fine features with high accuracy in manufacturing of electronic mobile devices has fueled growth for lasers in manufacturing. High power, high repetition rate ultraviolet (UV) lasers provide an opportunity to implement a cost effective high quality, high throughput micromachining process in a 24/7 manufacturing environment. The energy available per pulse and the pulse repetition frequency (PRF) of diode pumped solid state (DPSS) nanosecond UV lasers have increased steadily over the years. Efficient use of the available energy from a laser is important to generate accurate fine features at a high speed with high quality. To achieve maximum material removal and minimal thermal damage for any laser micromachining application, use of the optimal process parameters including energy density or fluence (J/cm2), pulse width, and repetition rate is important. In this study we present a new high power, high PRF QuasarR 355-40 laser from Spectra-Physics with TimeShiftTM technology for unique software adjustable pulse width, pulse splitting, and pulse shaping capabilities. The benefits of these features for micromachining include improved throughput and quality. Specific example and results of silicon scribing are described to demonstrate the processing benefits of the Quasar's available power, PRF, and TimeShift technology.

Light Conversion and Scattering in UV Protective Textiles

Directory of Open Access Journals (Sweden)

Grancarić Ana Marija

2014-12-01

Full Text Available The primary cause of skin cancer is believed to be a long exposure to solar ultraviolet radiation (UV-R crossed with the amount of skin pigmentation in the population. It is believed that in childhood and adolescence 80% of UV-R gets absorbed, whilst in the remaining 20% gets absorbed later in the lifetime. This suggests that proper and early photoprotection may reduce the risk of subsequent occurrence of skin cancer. Textile and clothing are the most suitable interface between environment and human body. It can show UV protection, but in most cases it does not provide full sun screening properties. UV protection ability highly depends on large number of factors such as type of fibre, fabric surface and construction, type and concentration of dyestuff, fluorescent whitening agent (FWA, UV-B protective agents, as well as nanoparticles, if applied. Based on electronically excited state by energy of UV-R (usually 340-370 nm, the molecules of FWAs show the phenomenon of fluorescence giving to white textiles high whiteness of outstanding brightness by reemitting the energy at the blue region (typically 420-470 nm of the spectrum. By absorbing UV-A radiation, optical brightened fabrics transform this radiation into blue fluorescence, which leads to better UV protection. Natural zeolites are rock-forming, microporous silicate minerals. Applied as nanoparticles to textile surface, it scatters the UV-R resulting in lower UV-A and UV-B transmission. If applied with other UV absorbing agents, e.g. FWAs, synergistic effect occurs. Silicones are inert, synthetic compounds with a variety of forms and uses. It provides a unique soft touch, is very resistant to washing and improves the property of fabric to protect against UV radiation. Therefore, the UV protective properties of cotton fabric achieved by light conversion and scattering was researched in this paper. For that purpose, the stilbene-derived FWAs were applied on cotton fabric in wide concentration

Disinfection by-product formation of UV treated swimming pool water

DEFF Research Database (Denmark)

Spiliotopoulou, Aikaterini; Hansen, Kamilla Marie Speht; Andersen, Henrik Rasmus

2015-01-01

Water samples from 3 indoor swimming pool facilities were tested to evaluate UV-induced effects on swimming pool water chemistry. Concentration change of several DBPs was investigated in experiments including medium pressure UV treatment with and without chlorine and post-UV chlorination. Post-UV...

Weightless Environment Training Facility (WETF) materials coating evaluation, volume 1

Science.gov (United States)

1995-01-01

The Weightless Environment Training Facility Material Coating Evaluation project has included preparing, coating, testing, and evaluating 800 test panels of three differing substrates. Ten selected coating systems were evaluated in six separate exposure environments and subject to three tests for physical properties. Substrate materials were identified, the manner of surface preparation described, and exposure environments defined. Exposure environments included immersion exposure, cyclic exposure, and field exposure. Cyclic exposures, specifically QUV-Weatherometer and the KTA Envirotest were found to be the most agressive of the environments included in the study when all three evaluation criteria are considered. This was found to result primarily from chalking of the coatings under ultraviolet (UV) light exposure. Volumes 2 and 3 hold the 5 appendices to this report.

Pilot-scale UV/H2O2 study for emerging organic contaminants decomposition.

Science.gov (United States)

Chu, Xiaona; Xiao, Yan; Hu, Jiangyong; Quek, Elaine; Xie, Rongjin; Pang, Thomas; Xing, Yongjie

2016-03-01

Human behaviors including consumption of drugs and use of personal care products, climate change, increased international travel, and the advent of water reclamation for direct potable use have led to the introduction of significant amounts of emerging organic contaminants into the aqueous environment. In addition, the lower detection limits associated with improved scientific methods of chemical analysis have resulted in a recent increase in documented incidences of these contaminants which previously were not routinely monitored in water. Such contaminants may cause known or suspected adverse ecological and/or human health effects at very low concentrations. Conventional drinking water treatment processes may not effectively remove these organic contaminants. Advanced oxidation process (AOP) is a promising treatment process for the removal of most of these emerging organic contaminants, and has been accepted worldwide as a suitable treatment process. In this study, different groups of emerging contaminants were studied for decomposition efficiency using pilot-scale UV/H2O2 oxidation setup, including EDCs, PPCPs, taste and odor (T&O), and perfluorinated compounds. Results found that MP UV/H2O2 AOP was efficient in removing all the selected contaminants except perfluorinated compounds. Study of the kinetics of the process showed that both light absorption and quantum yield of each compound affected the decomposition performance. Analysis of water quality parameters of the treated water indicated that the outcome of both UV photolysis and UV/H2O2 processes can be affected by changes in the feed water quality.

UV-B Perceived by the UVR8 Photoreceptor Inhibits Plant Thermomorphogenesis.

Science.gov (United States)

Hayes, Scott; Sharma, Ashutosh; Fraser, Donald P; Trevisan, Martine; Cragg-Barber, C Kester; Tavridou, Eleni; Fankhauser, Christian; Jenkins, Gareth I; Franklin, Keara A

2017-01-09

Small increases in ambient temperature can elicit striking effects on plant architecture, collectively termed thermomorphogenesis [1]. In Arabidopsis thaliana, these include marked stem elongation and leaf elevation, responses that have been predicted to enhance leaf cooling [2-5]. Thermomorphogenesis requires increased auxin biosynthesis, mediated by the bHLH transcription factor PHYTOCHROME-INTERACTING FACTOR 4 (PIF4) [6-8], and enhanced stability of the auxin co-receptor TIR1, involving HEAT SHOCK PROTEIN 90 (HSP90) [9]. High-temperature-mediated hypocotyl elongation additionally involves localized changes in auxin metabolism, mediated by the indole-3-acetic acid (IAA)-amido synthetase Gretchen Hagen 3 (GH3).17 [10]. Here we show that ultraviolet-B light (UV-B) perceived by the photoreceptor UV RESISTANCE LOCUS 8 (UVR8) [11] strongly attenuates thermomorphogenesis via multiple mechanisms inhibiting PIF4 activity. Suppression of thermomorphogenesis involves UVR8 and CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1)-mediated repression of PIF4 transcript accumulation, reducing PIF4 abundance. UV-B also stabilizes the bHLH protein LONG HYPOCOTYL IN FAR RED (HFR1), which can bind to and inhibit PIF4 function. Collectively, our results demonstrate complex crosstalk between UV-B and high-temperature signaling. As plants grown in sunlight would most likely experience concomitant elevations in UV-B and ambient temperature, elucidating how these pathways are integrated is of key importance to the understanding of plant development in natural environments. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Overview of UV and EB curing

International Nuclear Information System (INIS)

Garnett, J.L.

2000-01-01

Full text: UV and EB are complementary techniques in radiation curing. In the proposed paper, a brief review of both fields will be given. This will include principles of the process, the chemistry of the systems including monomers/oligomers/polymers used, additives required where necessary such as photoinitiators for UV, flow aids, adhesion promoters and the like. The types of equipment used in such processes will also be discussed including low energy electron beam utilisation and excimer curing. The advantages and disadvantages of both techniques will be examined. Mechanistic aspects of both curing systems will be discussed. Applications of the technology including developments in the banknote printing field will be summarised

Polyurethane acrylate networks including cellulose nanocrystals: a comparison between UV and EB- curing

Science.gov (United States)

Furtak-Wrona, K.; Kozik-Ostrówka, P.; Jadwiszczak, K.; Maigret, J. E.; Aguié-Béghin, V.; Coqueret, X.

2018-01-01

A water-based polyurethane (PUR) acrylate water emulsion was selected as a radiation curable matrix for preparing nanocomposites including cellulose nanocrystals (CNC) prepared by controlled hydrolysis of Ramie fibers. Cross-linking polymerization of samples prepared in the form of films or of 1 mm-thick bars was either initiated by exposure to the 395 nm light of a high intensity LED lamp or by treatment with low energy electron beam (EB). The conversion level of acrylate functions in samples submitted to increasing radiation doses was monitored by Fourier Transform Infrared Spectroscopy (FTIR). Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA) were used to characterize changes in the glass transition temperature of the PUR-CNC nanocomposites as a function of acrylate conversion and of CNC content. Micromechanical testing indicates the positive effect of 1 wt% CNC on Young's modulus and on the tensile strength at break (σ) of cured nanocomposites. The presence of CNC in the PUR acrylate matrix was shown to double the σ value of the nanocomposite cured to an acrylate conversion level of 85% by treatment with a 25 kGy dose under EB, whereas no increase of σ was observed in UV-cured samples exhibiting the same acrylate conversion level. The occurrence of grafting reactions inducing covalent linkages between the polysaccharide nanofiller and the PUR acrylate matrix during the EB treatment is advanced as an explanation to account for the improvement observed in samples cured under ionizing radiation.

The effectiveness of UV-C radiation for facility-wide environmental disinfection to reduce health care-acquired infections.

Science.gov (United States)

Napolitano, Nathanael A; Mahapatra, Tanmay; Tang, Weiming

2015-12-01

Health care-acquired infections (HAIs) constitute an increasing threat for patients worldwide. Potential contributors of HAIs include environmental surfaces in health care settings, where ultraviolet-C radiation (UV-C) is commonly used for disinfection. This UV-C intervention-based pilot study was conducted in a hospital setting to identify any change in the incidence of HAIs before and after UV-C intervention, and to determine the effectiveness of UV-C in reducing pathogens. In a hospital in Culver City, CA, during 2012-2013, bactericidal doses of UV-C radiation (254 nm) were delivered through a UV-C-based mobile environmental decontamination unit. The UV-C dosing technology and expertise of the specifically trained personnel were provided together as a dedicated service model by a contracted company. The incidence of HAIs before and after the intervention period were determined and compared. The dedicated service model dramatically reduced HAIs (incidence difference, 1.3/1000 patient-days, a 34.2% reduction). Reductions in the total number and incidence proportions (28.8%) of HAIs were observed after increasing and maintaining the coverage of UV-C treatments. The dedicated service model was found to be effective in decreasing the incidence of HAIs, which could reduce disease morbidity and mortality in hospitalized patients. This model provides a continuously monitored and frequently UV-C-treated patient environment. This approach to UV-C disinfection was associated with a decreased incidence of HAIs. Copyright © 2015 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

Implementation of UV-based advanced oxidation processes in algal medium recycling.

Science.gov (United States)

Wang, Wenxuan; Sha, Jun; Lu, Zhiying; Shao, Senlin; Sun, Peizhe; Hu, Qiang; Zhang, Xuezhi

2018-09-01

Algae show great potential as sustainable feedstock for numerous bioproducts. However, large volume of water consumption during algal biomass production makes that the culture media recycling is a necessity due to economic and environmental concern. To avoid the negative effect of enriched organic matters in the harvested culture media, pre-treatment prior to medium replenishment and reuse is required. In this study, degradation of algenitic organic matters (AOM) in the culture media by UV-based photolysis processes (i.e., direct UV, UV/peroxydisulfate (PDS), UV/H 2 O 2 , and UV/NH 2 Cl) was explored. The results showed that UV, UV/PDS, UV/H 2 O 2 and UV/NH 2 Cl caused a decrease of SUVA for 29.9%, 35.4%, 40.45%, and 22.6%, respectively, though the organic matter was almost not mineralized. Fluorescence excitation-emission matrix combined with parallel factor analysis indicated that UV/PDS and UV/H 2 O 2 degraded 47.26%-56.31% of the fulvic-like and humic-like fractions in AOM. Powder activated carbon absorption and growth evaluation for the AOPs-treated media indicated that UV/PDS and UV/H 2 O 2 processes not only could remove the growth inhibitors in the media, but were also beneficial to the algae growth. These results suggested that UV/PDS and UV/H 2 O 2 could effectively degrade the hydrophobic components in AOM and converted the growth inhibition fraction of AOM in the recycled media into nutrient source for algal growth. Different from the general application of UV-based AOP in the wastewater treatment, this study provided an innovative idea about how to pre-treat AOM in the media recycling: utilization rather than removal, which was a more sustainable and environment-friendly technology. Copyright © 2018 Elsevier B.V. All rights reserved.

UV spectroscopy. Ch. 16

International Nuclear Information System (INIS)

Stevens, Eugene S.

1991-01-01

The use of synchrotron radiation (SR) in the ultraviolet (UV) region by biophysics and biophysical chemists continues to increase as access improves and as awareness of its unique combination of properties grows. SR is continuously tunable, intense (even in the UV region), and pulsed. Pulse characteristics are comparable to those of picosecond lasers, but have the advantage of being independent of wavelength. Drawbacks are the continuous, but slow, decay of intensity arising from loss of particles in the ring, and the intrinsic limitation in pulse repetition rate. The particular combination of features that makes SR a superior light source depends upon the application. Spectroscopic techniques based on absorption and some techniques based on emission exploit its intensity and continuous tunability; time resolved techniques make use of its pulse characteristics. This chapter is a status report on two of the major biological applications of UV SR, circular dichroism and time-resolved fluorescence, covering mainly the published literature of the last five years. For the present purpose, the term UV is understood to include the vacuum ultraviolet region to 100 nm. (author). 83 refs.; 4 figs.; 6 tabs

Effect of UV-Blocking Plastic Films on Take-Off and Host Plant Finding Ability of Diaphorina citri (Hemiptera: Liviidae).

Science.gov (United States)

Miranda, M P; Dos Santos, F L; Felippe, M R; Moreno, A; Fereres, A

2015-02-01

The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is a major pest of citrus worldwide due to its ability to transmit the bacteria associated with huanglongbing. Vision, behavior, and performance of insect pests can be manipulated by using ultraviolet (UV)-blocking materials. Thus, the aim of our study was to evaluate how UV-blocking plastic films may affect the take-off and host plant finding ability of D. citri. To assess the effect of a UV-deficient environment on take-off, adult psyllids were released from a vial inside a screenhouse covered by a UV-blocking or standard (control) film and the number of insects remaining on each vial under each treatment was counted at different time intervals. Moreover, to assess the ability of D. citri to find citrus plants under a UV-deficient environment, two independent no-choice host plant finding assays with different plant arrangements were conducted. In each treatment, the number of psyllids per plant at different time intervals was counted. Both D. citri take-off and host plant finding ability was clearly disrupted under a UV-deficient environment. The number of psyllids remaining in the vials was significantly higher under UV-blocking than standard film in all periods recorded. Furthermore, psyllids were present in significantly higher number on citrus plants under standard film than under UV-blocking film in all of the periods assessed and experiments conducted. Our results showed that UV-blocking materials could become a valuable strategy for integrated management of D. citri and huanglongbing in citrus grown in enclosed environments. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Improving UV Resistance of High Performance Fibers

Science.gov (United States)

Hassanin, Ahmed

High performance fibers are characterized by their superior properties compared to the traditional textile fibers. High strength fibers have high modules, high strength to weight ratio, high chemical resistance, and usually high temperature resistance. It is used in application where superior properties are needed such as bulletproof vests, ropes and cables, cut resistant products, load tendons for giant scientific balloons, fishing rods, tennis racket strings, parachute cords, adhesives and sealants, protective apparel and tire cords. Unfortunately, Ultraviolet (UV) radiation causes serious degradation to the most of high performance fibers. UV lights, either natural or artificial, cause organic compounds to decompose and degrade, because the energy of the photons of UV light is high enough to break chemical bonds causing chain scission. This work is aiming at achieving maximum protection of high performance fibers using sheathing approaches. The sheaths proposed are of lightweight to maintain the advantage of the high performance fiber that is the high strength to weight ratio. This study involves developing three different types of sheathing. The product of interest that need be protected from UV is braid from PBO. First approach is extruding a sheath from Low Density Polyethylene (LDPE) loaded with different rutile TiO2 % nanoparticles around the braid from the PBO. The results of this approach showed that LDPE sheath loaded with 10% TiO2 by weight achieved the highest protection compare to 0% and 5% TiO2. The protection here is judged by strength loss of PBO. This trend noticed in different weathering environments, where the sheathed samples were exposed to UV-VIS radiations in different weatheromter equipments as well as exposure to high altitude environment using NASA BRDL balloon. The second approach is focusing in developing a protective porous membrane from polyurethane loaded with rutile TiO2 nanoparticles. Membrane from polyurethane loaded with 4

High-performance visible/UV CCD focal plane technology for spacebased applications

Science.gov (United States)

Burke, B. E.; Mountain, R. W.; Gregory, J. A.; Huang, J. C. M.; Cooper, M. J.; Savoye, E. D.; Kosicki, B. B.

1993-01-01

We describe recent technology developments aimed at large CCD imagers for space based applications in the visible and UV. Some of the principal areas of effort include work on reducing device degradation in the natural space-radiation environment, improvements in quantum efficiency in the visible and UV, and larger-device formats. One of the most serious hazards for space based CCD's operating at low signal levels is the displacement damage resulting from bombardment by energetic protons. Such damage degrades charge-transfer efficiency and increases dark current. We have achieved improved hardness to proton-induced displacement damage by selective ion implants into the CCD channel and by reduced temperature of operation. To attain high quantum efficiency across the visible and UV we have developed a technology for back-illuminated CCD's. With suitable antireflection (AR) coatings such devices have quantum efficiencies near 90 percent in the 500-700-nm band. In the UV band from 200 to 400 nm, where it is difficult to find coatings that are sufficiently transparent and can provide good matching to the high refractive index of silicon, we have been able to substantially increase the quantum efficiency using a thin film of HfO2 as an AR coating. These technology efforts were applied to a 420 x 420-pixel frame-transfer imager, and future work will be extended to a 1024 x 1024-pixel device now under development.

Soft, stretchable, epidermal sensor with integrated electronics and photochemistry for measuring personal UV exposures.

Science.gov (United States)

Shi, Yunzhou; Manco, Megan; Moyal, Dominique; Huppert, Gil; Araki, Hitoshi; Banks, Anthony; Joshi, Hemant; McKenzie, Richard; Seewald, Alex; Griffin, Guy; Sen-Gupta, Ellora; Wright, Donald; Bastien, Philippe; Valceschini, Florent; Seité, Sophie; Wright, John A; Ghaffari, Roozbeh; Rogers, John; Balooch, Guive; Pielak, Rafal M

2018-01-01

Excessive ultraviolet (UV) radiation induces acute and chronic effects on the skin, eye and immune system. Personalized monitoring of UV radiation is thus paramount to measure the extent of personal sun exposure, which could vary with environment, lifestyle, and sunscreen use. Here, we demonstrate an ultralow modulus, stretchable, skin-mounted UV patch that measures personal UV doses. The patch contains functional layers of ultrathin stretchable electronics and a photosensitive patterned dye that reacts to UV radiation. Color changes in the photosensitive dyes correspond to UV radiation intensity and are analyzed with a smartphone camera. A software application has feature recognition, lighting condition correction, and quantification algorithms that detect and quantify changes in color. These color changes are then correlated with corresponding shifts in UV dose, and compared to existing UV dose risk levels. The soft mechanics of the UV patch allow for multi-day wear in the presence of sunscreen and water. Two evaluation studies serve to demonstrate the utility of the UV patch during daily activities with and without sunscreen application.

Soft, stretchable, epidermal sensor with integrated electronics and photochemistry for measuring personal UV exposures

Science.gov (United States)

Shi, Yunzhou; Manco, Megan; Moyal, Dominique; Huppert, Gil; Araki, Hitoshi; Banks, Anthony; Joshi, Hemant; McKenzie, Richard; Seewald, Alex; Griffin, Guy; Sen-Gupta, Ellora; Wright, Donald; Bastien, Philippe; Valceschini, Florent; Seité, Sophie; Wright, John A.; Ghaffari, Roozbeh; Rogers, John; Balooch, Guive

2018-01-01

Excessive ultraviolet (UV) radiation induces acute and chronic effects on the skin, eye and immune system. Personalized monitoring of UV radiation is thus paramount to measure the extent of personal sun exposure, which could vary with environment, lifestyle, and sunscreen use. Here, we demonstrate an ultralow modulus, stretchable, skin-mounted UV patch that measures personal UV doses. The patch contains functional layers of ultrathin stretchable electronics and a photosensitive patterned dye that reacts to UV radiation. Color changes in the photosensitive dyes correspond to UV radiation intensity and are analyzed with a smartphone camera. A software application has feature recognition, lighting condition correction, and quantification algorithms that detect and quantify changes in color. These color changes are then correlated with corresponding shifts in UV dose, and compared to existing UV dose risk levels. The soft mechanics of the UV patch allow for multi-day wear in the presence of sunscreen and water. Two evaluation studies serve to demonstrate the utility of the UV patch during daily activities with and without sunscreen application. PMID:29293664

Soft, stretchable, epidermal sensor with integrated electronics and photochemistry for measuring personal UV exposures.

Directory of Open Access Journals (Sweden)

Yunzhou Shi

Full Text Available Excessive ultraviolet (UV radiation induces acute and chronic effects on the skin, eye and immune system. Personalized monitoring of UV radiation is thus paramount to measure the extent of personal sun exposure, which could vary with environment, lifestyle, and sunscreen use. Here, we demonstrate an ultralow modulus, stretchable, skin-mounted UV patch that measures personal UV doses. The patch contains functional layers of ultrathin stretchable electronics and a photosensitive patterned dye that reacts to UV radiation. Color changes in the photosensitive dyes correspond to UV radiation intensity and are analyzed with a smartphone camera. A software application has feature recognition, lighting condition correction, and quantification algorithms that detect and quantify changes in color. These color changes are then correlated with corresponding shifts in UV dose, and compared to existing UV dose risk levels. The soft mechanics of the UV patch allow for multi-day wear in the presence of sunscreen and water. Two evaluation studies serve to demonstrate the utility of the UV patch during daily activities with and without sunscreen application.

Significant role of UV and carbonate radical on the degradation of oxytetracycline in UV-AOPs: Kinetics and mechanism.

Science.gov (United States)

Liu, Yiqing; He, Xuexiang; Duan, Xiaodi; Fu, Yongsheng; Fatta-Kassinos, Despo; Dionysiou, Dionysios D

2016-05-15

Carbonate radical (CO3(•-)), a selective oxidant, reacts readily with electron-rich compounds through electron transfer and/or hydrogen abstraction. In this study, the role of CO3(•-) in degrading oxytetracycline (OTC) by UV only, UV/H2O2 and UV/persulfate (UV/PS) advanced oxidation processes (AOPs) in the presence of HCO3(-) or CO3(2-) was investigated. For UV only process, the presence of photosensitizers, i.e., nitrate (NO3(-)) and natural organic matter (NOM), had different impacts on OTC degradation, i.e., an enhancing effect by NO3(-) due to the generation of HO(•) and a slight inhibiting effect by NOM possibly due to a light scattering effect. Differently for UV/H2O2 and UV/PS processes, the presence of NO3(-) hardly influenced the destruction of OTC. Generation of CO3(•-) presented a positive role on OTC degradation by UV/NO3(-)/HCO3(-). Such influence was also observed in the two studied AOPs in the presence of both bicarbonate and other natural water constituents. When various natural water samples from different sources were used as reaction matrices, UV only and UV/H2O2 showed an inhibiting effect while UV/PS demonstrated a comparable or even promoting effect in OTC decomposition. After elucidating the potential contribution of UV direct photolysis via excited state OTC* at an elevated reaction pH condition, putative OTC transformation byproducts via CO3(•-) reaction were identified by ultra-high definition accurate-mass quadrupole time-of-flight tandem mass spectrometry (QTOF/MS). Five different reaction pathways were subsequently proposed, including hydroxylation (+16 Da), quinonization (+14 Da), demethylation (-14 Da), decarbonylation (-28 Da) and dehydration (-18 Da). The significant role of UV at high pH and CO3(•-) on OTC removal from contaminated water was therefore demonstrated both kinetically and mechanistically. Copyright © 2016 Elsevier Ltd. All rights reserved.

Waterborne UV coating for industrial applications

International Nuclear Information System (INIS)

Bhattacharya, I.N.

2007-01-01

(Full Text): Solvent borne industrial coatings are being replaced by environment friendly coatings like Ultra Violet (UV) or Electron Beam (Eb) cured coatings, Powder coatings and Waterborne coatings. Waterborne systems enjoy the biggest share from this shift. UV and EB coatings provide the advantages of instant cure at room temperature, high scratch and abrasion resistance combined with excellent chemical resistance. Polyurethane (PU) chemistry is the dominant chemistry in Industrial coatings as they provide a very high level of performance. Most PU coatings are solvent based 2-component systems comprising of a resin and a cross linker. Polyurethane dispersions (PUD) in water in single pack are available but mainly addresses the Do It Yourself (DIY) market because of their slow drying speeds. Performance of PUD in most cases is inferior to solvent borne 2-component PU systems.Therefore the combination of PU dispersion and UV/EB curable technology has led to new innovative waterborne polymers called UV curable polyurethane dispersions (UVPUD). UVPUD are zero VOC systems as they are coalescent free. They are higher in molecular weight than standard UV curable products resulting in lower shrinkage coatings and provide good adhesion to substrates. Their low-viscosity makes them suitable for application by spray, curtain coater and even roller coater, without having to use monomers. UVPUD display superior chemical and mechanical properties necessary to protect high quality surface from the challenging usage conditions. UVPUD resins are therefore tailor-made to address performance needs like excellence in outdoor durability, scratch resistance, stain resistance, adhesion etc. UVPUD technology is now growing rapidly in industrial coatings for applications such as resilient flooring, wooden parquet flooring, automotive interior plastics, mobile phones etc. (Author)

New technologies for UV detectors

Science.gov (United States)

Joseph, C. L.

1993-01-01

Several technologies are currently being developed, leading to substantial improvements in the performance of UV detectors or significant reductions in power or weight. Four technologies discussed are (1) thin-film coatings to enhance the UV sensitivity of CCD's, (2) highly innovative magnet assemblies that dramatically reduce weight and result in virtually no external flux, (3) new techniques for curving microchannel plates (MCP's) so that single plates can be used to prevent ion feedback and present highly localized charge clouds to an anode structure, and (4) high-performance alternatives to glass-based MCP's. In item (2), for example, very robust magnets are made out of rare earth materials such as samarium cobalt, and cladding magnets are employed to prevent flux from escaping from the detector into the external environment. These new ultralight magnet assemblies are able to create strong, exceptionally uniform magnetic fields for image intensification and focusing of photoelectrons. The principle advantage of such detectors is the quantum efficiencies of 70-80 percent obtained throughout ultraviolet wavelengths (900-2000 A), the highest of any device. Despite the improvements achieved under item (3), high-performance alternatives to conventional glass-based MCP's potentially offer three distinct new advantages that include (1) a 30-100-fold improvement in dynamic range resulting in correspondingly higher signal-to-noise ratios, (2) the use of pure dielectric and semiconductor materials that will not outgas contaminants that eventually destroy photocathodes, and (3) channels that have constant spacing providing long-ranged order since the plates are made using photolithography techniques from the semiconductor industry. The manufacturers of these advanced-technology MCP's, however, are a couple of years away from actually producing a functioning image intensifier. In contrast to the use of CCD's for optical, ground based observations, there is no single

Co-ordinated ozone and UV project COZUV

International Nuclear Information System (INIS)

Braathen, Geir

1999-01-01

The project encompasses all the major Norwegian research groups in the field of stratospheric ozone and UV research. the duration is from the 1st January 1999 to the 31st December 2000. The tasks carried out will include investigations of the ozone layer over the North Polar and middle latitudes, 3-D chemical modelling, diagnosis of chemical ozone loss, investigations of transport mechanisms between the polar vortex and middle latitudes, study of the coupling between ozone change and climate change in the stratosphere and upper troposphere, scenario calculations in order to investigate the consequences of temperature change in the stratosphere, development of methods to measure global, direct and radiance distribution of UV, to improve UV dose calculations, investigate the influence of clouds on the surface UV radiation and to use existing surface UV radiation measurements together with existing radiation models to investigate the connection between UV radiation and ozone, clouds and surface albedo. The results will be published in various publications, progress reports, by participation in international conferences, through information to the environmental authorities and through information on the Internet

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

Development of a low cost UV index datalogger and comparison between UV index sensors

Science.gov (United States)

Gomes, L. M.; Ventura, L.

2018-02-01

Ultraviolet radiation (UVR) is the part of radiation emitted by the Sun, with range between 280 nm and 400 nm, and that reaches the Earth's surface. The UV rays are essential to the human because it stimulates the production of vitamin D but this radiation may be related to several health problems, including skin cancer and ocular diseases like pterygium, photokeratitis, cataract and more. To inform people about UV radiation, it is adopted the Ultraviolet Index (UVI). This UVI consists in a measure of solar UV radiation level, which contributes to cause sunburn on skin, also known as Erythema, and is indicated as an integer number between 1 and 14, associated to categories from low to extreme respectively. The aim of this work was to develop a low cost UVI datalogger capable of measuring three different UVI sensors simultaneously, record their data with timestamp and serve the measures online through a dedicated server, so general public can access their data and see the current UV radiation conditions. We also compared three different UVI sensors (SGlux UV cosine, Skye SKU440 and SiLabs SI1145) between them and with meteorological models during a period of months to verify their compliance. With five months data, we could verify the sensors working characteristics and decide which among them are the most suitable for research purposes.

The response of human skin commensal bacteria as a reflection of UV radiation: UV-B decreases porphyrin production.

Directory of Open Access Journals (Sweden)

Yanhan Wang

Full Text Available Recent global radiation fears reflect the urgent need for a new modality that can simply determine if people are in a radiation risk of developing cancer and other illnesses. Ultraviolet (UV radiation has been thought to be the major risk factor for most skin cancers. Although various biomarkers derived from the responses of human cells have been revealed, detection of these biomarkers is cumbersome, probably requires taking live human tissues, and varies significantly depending on human immune status. Here we hypothesize that the reaction of Propionibacterium acnes (P. acnes, a human resident skin commensal, to UV radiation can serve as early surrogate markers for radiation risk because the bacteria are immediately responsive to radiation. In addition, the bacteria can be readily accessible and exposed to the same field of radiation as human body. To test our hypothesis, P. acnes was exposed to UV-B radiation. The production of porphyrins in P. acnes was significantly reduced with increasing doses of UV-B. The porphyrin reduction can be detected in both P. acnes and human skin bacterial isolates. Exposure of UV-B to P. acnes- inoculated mice led to a significant decrease in porphyrin production in a single colony of P. acnes and simultaneously induced the formation of cyclobutane pyrimidine dimers (CPD in the epidermal layers of mouse skin. Mass spectrometric analysis via a linear trap quadrupole (LTQ-Orbitrap XL showed that five peptides including an internal peptide (THLPTGIVVSCQNER of a peptide chain release factor 2 (RF2 were oxidized by UV-B. Seven peptides including three internal peptides of 60 kDa chaperonin 1 were de-oxidized by UV-B. When compared to UV-B, gamma radiation also decreased the porphyrin production of P. acnes in a dose-dependent manner, but induced a different signature of protein oxidation/de-oxidation. We highlight that uncovering response of skin microbiome to radiation will facilitate the development of pre

The response of human skin commensal bacteria as a reflection of UV radiation: UV-B decreases porphyrin production.

Science.gov (United States)

Wang, Yanhan; Zhu, Wenhong; Shu, Muya; Jiang, Yong; Gallo, Richard L; Liu, Yu-Tsueng; Huang, Chun-Ming

2012-01-01

Recent global radiation fears reflect the urgent need for a new modality that can simply determine if people are in a radiation risk of developing cancer and other illnesses. Ultraviolet (UV) radiation has been thought to be the major risk factor for most skin cancers. Although various biomarkers derived from the responses of human cells have been revealed, detection of these biomarkers is cumbersome, probably requires taking live human tissues, and varies significantly depending on human immune status. Here we hypothesize that the reaction of Propionibacterium acnes (P. acnes), a human resident skin commensal, to UV radiation can serve as early surrogate markers for radiation risk because the bacteria are immediately responsive to radiation. In addition, the bacteria can be readily accessible and exposed to the same field of radiation as human body. To test our hypothesis, P. acnes was exposed to UV-B radiation. The production of porphyrins in P. acnes was significantly reduced with increasing doses of UV-B. The porphyrin reduction can be detected in both P. acnes and human skin bacterial isolates. Exposure of UV-B to P. acnes- inoculated mice led to a significant decrease in porphyrin production in a single colony of P. acnes and simultaneously induced the formation of cyclobutane pyrimidine dimers (CPD) in the epidermal layers of mouse skin. Mass spectrometric analysis via a linear trap quadrupole (LTQ)-Orbitrap XL showed that five peptides including an internal peptide (THLPTGIVVSCQNER) of a peptide chain release factor 2 (RF2) were oxidized by UV-B. Seven peptides including three internal peptides of 60 kDa chaperonin 1 were de-oxidized by UV-B. When compared to UV-B, gamma radiation also decreased the porphyrin production of P. acnes in a dose-dependent manner, but induced a different signature of protein oxidation/de-oxidation. We highlight that uncovering response of skin microbiome to radiation will facilitate the development of pre-symptomatic diagnosis

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.

UV-B Perception and Acclimation in Chlamydomonas reinhardtii[OPEN

Science.gov (United States)

Chappuis, Richard; Allorent, Guillaume

2016-01-01

Plants perceive UV-B, an intrinsic component of sunlight, via a signaling pathway that is mediated by the photoreceptor UV RESISTANCE LOCUS8 (UVR8) and induces UV-B acclimation. To test whether similar UV-B perception mechanisms exist in the evolutionarily distant green alga Chlamydomonas reinhardtii, we identified Chlamydomonas orthologs of UVR8 and the key signaling factor CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1). Cr-UVR8 shares sequence and structural similarity to Arabidopsis thaliana UVR8, has conserved tryptophan residues for UV-B photoreception, monomerizes upon UV-B exposure, and interacts with Cr-COP1 in a UV-B-dependent manner. Moreover, Cr-UVR8 can interact with At-COP1 and complement the Arabidopsis uvr8 mutant, demonstrating that it is a functional UV-B photoreceptor. Chlamydomonas shows apparent UV-B acclimation in colony survival and photosynthetic efficiency assays. UV-B exposure, at low levels that induce acclimation, led to broad changes in the Chlamydomonas transcriptome, including in genes related to photosynthesis. Impaired UV-B-induced activation in the Cr-COP1 mutant hit1 indicates that UVR8-COP1 signaling induces transcriptome changes in response to UV-B. Also, hit1 mutants are impaired in UV-B acclimation. Chlamydomonas UV-B acclimation preserved the photosystem II core proteins D1 and D2 under UV-B stress, which mitigated UV-B-induced photoinhibition. These findings highlight the early evolution of UVR8 photoreceptor signaling in the green lineage to induce UV-B acclimation and protection. PMID:27020958

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

Microbial UV fluence-response assessment using a novel UV-LED collimated beam system.

Science.gov (United States)

Bowker, Colleen; Sain, Amanda; Shatalov, Max; Ducoste, Joel

2011-02-01

A research study has been performed to determine the ultraviolet (UV) fluence-response of several target non-pathogenic microorganisms to UV light emitting diodes (UV-LEDs) by performing collimated beam tests. UV-LEDs do not contain toxic mercury, offer design flexibility due to their small size, and have a longer operational life than mercury lamps. Comsol Multiphysics was utilized to create an optimal UV-LED collimated beam design based on number and spacing of UV-LEDs and distance of the sample from the light source while minimizing the overall cost. The optimized UV-LED collimated beam apparatus and a low-pressure mercury lamp collimated beam apparatus were used to determine the UV fluence-response of three surrogate microorganisms (Escherichia coli, MS-2, T7) to 255 nm UV-LEDs, 275 nm UV-LEDs, and 254 nm low-pressure mercury lamps. Irradiation by low-pressure mercury lamps produced greater E. coli and MS-2 inactivation than 255 nm and 275 nm UV-LEDs and similar T7 inactivation to irradiation by 275 nm UV-LEDs. The 275 nm UV-LEDs produced more efficient T7 and E. coli inactivation than 255 nm UV-LEDs while both 255 nm and 275 nm UV-LEDs produced comparable microbial inactivation for MS-2. Differences may have been caused by a departure from the time-dose reciprocity law due to microbial repair mechanisms. Copyright © 2010 Elsevier Ltd. All rights reserved.

Biobased Nanoparticles for Broadband UV Protection with Photostabilized UV Filters

NARCIS (Netherlands)

Hayden, D.R.|info:eu-repo/dai/nl/412640694; Imhof, A.|info:eu-repo/dai/nl/145641600; Velikov, K. P.|info:eu-repo/dai/nl/239483472

2016-01-01

Sunscreens rely on multiple compounds to provide effective and safe protection against UV radiation. UV filters in sunscreens, in particular, provide broadband UV protection but are heavily linked to adverse health effects due to the generation of carcinogenic skin-damaging reactive oxygen species

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...

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

DNA damage caused by UV- and near UV-irradiation

International Nuclear Information System (INIS)

Ohnishi, Takeo

1986-01-01

Much work with mutants deficient in DNA repair has been performed concerning UV-induced DNA damage under the condition where there is no artificial stimulation. In an attempt to infer the effects of solar wavelengths, the outcome of the work is discussed in terms of cellular radiation sensitivity, unscheduled DNA synthesis, and mutation induction, leading to the conclusion that some DNA damage occurs even by irradiation of the shorter wavelength light (270 - 315 nm) and is repaired by excision repair. It has been thought to date that pyrimidine dimer (PD) plays the most important role in UV-induced DNA damage, followed by (6 - 4) photoproducts. As for DNA damage induced by near UV irradiation, the yield of DNA single-strand breaks and of DNA-protein crosslinking, other than PD, is considered. The DNA-protein crosslinking has proved to be induced by irradiation at any wavelength of UV ranging from 260 to 425 nm. Near UV irradiation causes the inhibition of cell proliferation to take place. (Namekawa, K.)

UV curable palm oil based ink

International Nuclear Information System (INIS)

Mek Zah Salleh; Mohd Hilmi Mahmood; Khairul Zaman Mohd Dahlan; Rosley Che Ismail

2002-01-01

UV curable inks are useful for their instant drying, energy saving and high productivity properties. The basic materials for formulating UV curable inks consist of prepolymer, monomers, photoinitiators, pigments and other additives. The percentage composition and ingredients depend very much on the types of inks to be produced. Palm oil is one of the main raw materials available in the country. Hence, the diversification of palm oil derivatives into new products has been given priority. The current focus of the present work is to evaluate the use of palm oil urethane acrylate (POBUA) as a prepolymer in the UV ink system. A study was conducted on the use of POBUA with other materials in ink formulation. These include the types and concentration of photoinitiators, monomers and commercial urethane acrylates. The evaluation of the ink properties such as curing, adhesion, color density have been carried out. It was found that POBUA could be introduced in the UV ink system. (Author)

UV curable palm oil based inks

International Nuclear Information System (INIS)

Mek Zah Salleh; Hilmi Mahmood

2002-01-01

UV curable inks are useful for their instant drying, energy saving and high productivity properties. The basic materials for formulating UV curable inks consist of prepolymer, monomers, photoinitiators, pigments and other additives. The percentage composition and ingredients depend very much on the types of inks to be produced. Palm oil is one of the main raw materials available in the country. Hence, the diversification of palm oil derivatives into new products has been given priority. The current focus of the present work is to evaluate the use of palm oil based urethane acrylate (POBUA) as a prepolymer in the UV inks system. A study was conducted on the use of POBUA with other materials in ink formulation. These include the types and concentration of photoinitiators, monomers and commercial urethane acrylates. The evaluation of the ink properties such as curing, adhesion, color density have been carried out. It was found that POBUA could be introduced in the UV ink system. (Author)

UV light and urban pollution: Bad cocktail for mosquitoes?

International Nuclear Information System (INIS)

Tetreau, Guillaume; Chandor-Proust, Alexia; Faucon, Frédéric; Stalinski, Renaud; Akhouayri, Idir; Prud’homme, Sophie M.; Régent-Kloeckner, Myriam; Raveton, Muriel; Reynaud, Stéphane

2014-01-01

Highlights: •Mosquito tolerance to temephos is induced by PAHs and UV exposure. •Toxicity of fluoranthene for mosquito Malpighian tubules cells is induced by UV. •Fluoranthene crystallizes in mosquito Malpighian tubules upon UV exposure. •Mixture of two PAHs is less toxic for mosquitoes than each PAHs separately. •Combination of abiotic parameters (PAHs and UV) affect mosquito physiology. -- Abstract: Mosquito breeding sites consist of water pools, which can either be large open areas or highly covered ponds with vegetation, thus with different light exposures combined with the presence in water of xenobiotics including polycyclic aromatic hydrocarbons (PAHs) generated by urban pollution. UV light and PAHs are abiotic factors known to both affect the mosquito insecticide resistance status. Nonetheless, their potential combined effects on the mosquito physiology have never been investigated. The present article aims at describing the effects of UV exposure alongside water contamination with two major PAH pollutants (fluoranthene and benzo[a]pyrene) on a laboratory population of the yellow fever mosquito Aedes aegypti. To evaluate the effects of PAH exposure and low energetic UV (UV-A) irradiation on mosquitoes, different parameters were measured including: (1) The PAH localization and its impact on cell mortality by fluorescent microscopy; (2) The detoxification capacities (cytochrome P450, glutathione-S-transferase, esterase); (3) The responses to oxidative stress (Reactive Oxygen Species–ROS) and (4) The tolerance of mosquito larvae to a bioinsecticide (Bacillus thuringiensis subsp. israelensis–Bti) and to five chemical insecticides (DDT, imidacloprid, permethrin, propoxur and temephos). Contrasting effects regarding mosquito cell mortality, detoxification and oxidative stress were observed as being dependent on the pollutant considered, despite the fact that the two PAHs belong to the same family. Moreover, UV is able to modify pollutant effects on

UV light and urban pollution: Bad cocktail for mosquitoes?

Energy Technology Data Exchange (ETDEWEB)

Tetreau, Guillaume, E-mail: guillaume.tetreau@gmail.com [Laboratoire d’Ecologie Alpine, LECA-UMR 5553, Université de Grenoble 1, BP 53, 38041 Grenoble cedex 09 (France); Department of Entomology, Cornell University, New York State Agricultural Experiment Station, Geneva, NY 14456 (United States); Chandor-Proust, Alexia; Faucon, Frédéric; Stalinski, Renaud; Akhouayri, Idir; Prud’homme, Sophie M.; Régent-Kloeckner, Myriam; Raveton, Muriel; Reynaud, Stéphane [Laboratoire d’Ecologie Alpine, LECA-UMR 5553, Université de Grenoble 1, BP 53, 38041 Grenoble cedex 09 (France)

2014-01-15

Highlights: •Mosquito tolerance to temephos is induced by PAHs and UV exposure. •Toxicity of fluoranthene for mosquito Malpighian tubules cells is induced by UV. •Fluoranthene crystallizes in mosquito Malpighian tubules upon UV exposure. •Mixture of two PAHs is less toxic for mosquitoes than each PAHs separately. •Combination of abiotic parameters (PAHs and UV) affect mosquito physiology. -- Abstract: Mosquito breeding sites consist of water pools, which can either be large open areas or highly covered ponds with vegetation, thus with different light exposures combined with the presence in water of xenobiotics including polycyclic aromatic hydrocarbons (PAHs) generated by urban pollution. UV light and PAHs are abiotic factors known to both affect the mosquito insecticide resistance status. Nonetheless, their potential combined effects on the mosquito physiology have never been investigated. The present article aims at describing the effects of UV exposure alongside water contamination with two major PAH pollutants (fluoranthene and benzo[a]pyrene) on a laboratory population of the yellow fever mosquito Aedes aegypti. To evaluate the effects of PAH exposure and low energetic UV (UV-A) irradiation on mosquitoes, different parameters were measured including: (1) The PAH localization and its impact on cell mortality by fluorescent microscopy; (2) The detoxification capacities (cytochrome P450, glutathione-S-transferase, esterase); (3) The responses to oxidative stress (Reactive Oxygen Species–ROS) and (4) The tolerance of mosquito larvae to a bioinsecticide (Bacillus thuringiensis subsp. israelensis–Bti) and to five chemical insecticides (DDT, imidacloprid, permethrin, propoxur and temephos). Contrasting effects regarding mosquito cell mortality, detoxification and oxidative stress were observed as being dependent on the pollutant considered, despite the fact that the two PAHs belong to the same family. Moreover, UV is able to modify pollutant effects on

UV astronomy throughout the ages: a historical perspective

Science.gov (United States)

Linsky, Jeffrey L.

2018-05-01

Astronomers have long recognized the critical need for ultraviolet imaging, photometry and spectroscopy of stars, planets, and galaxies, but this need could not be satisfied without access to space and the development of efficient instrumentation. When UV measurements became feasible, first with rockets and then with satellites, major discoveries came rapidly. It is true in the UV spectral region as in all others, that significant increases in sensitivity, spectral resolution, and time domain coverage have led to significant new understanding of astrophysical phenomena. I will describe a selection of these discoveries made in each of three eras: (1) the early history of rocket instrumentation and Copernicus, the first UV satellite, (2) the discovery phase pioneered by the IUE, FUSE and EUVE satellites, and (3) the full flowering of UV astronomy with the successful operation of HST and its many instruments. I will also mention a few areas where future UV instrumentation could lead to new discoveries. This review concentrates on developments in stellar and interstellar UV spectroscopy; the major discoveries in galactic, extragalactic, and solar system research are beyond the scope of this review. The important topic of UV technologies and detectors, which enable the remarkable advances in UV astronomy are also not included in this review.

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

The effects of near-UV radiation on elasmobranch lens cytoskeletal actin.

Science.gov (United States)

Zigman, S; Rafferty, N S; Scholz, D L; Lowe, K

1992-08-01

The role of near-UV radiation as a cytoskeletal actin-damaging agent was investigated. Two procedures were used to analyse fresh smooth dogfish (Mustelus canis) eye lenses that were incubated for up to 22 hr in vitro, with elasmobranch Ringer's medium, and with or without exposure to a near-UV lamp (emission principally at 365 nm; irradiance of 2.5 mW cm-2). These were observed histologically using phalloidin-rhodamine specific staining and by transmission electron microscopy. In addition, solutions of purified polymerized rabbit muscle actin were exposed to the same UV conditions and depolymerization was assayed by ultracentrifugation and high-pressure liquid chromatography. While the two actins studied do differ very slightly in some amino acid sequences, they would react physically nearly identically. The results showed that dogfish lenses developed superficial opacities due to near-UV exposure. Whole mounts of lens epithelium exhibited breakdown of actin filaments in the basal region of the cells within 18 hr of UV exposure. TEM confirmed the breakdown of actin filaments due to UV exposure. SDS-PAGE and immunoblotting positively identified actin in these cells. Direct exposure of purified polymerized muscle actin in polymerizing buffer led to an increase in actin monomer of approximately 25% in the UV-exposed solutions within 3-18 hr, whether assayed by ultracentrifugation or HPLC. The above indicates that elasmobranch lens epithelial cells contain UV-labile actin filaments, and that near-UV radiation, as is present in the sunlit environment, can break down the actin structure in these cells. Furthermore, breakdown of purified polymerized muscle actin does occur due to near-UV light exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Lifestyle, sun worshipping and sun tanning - what about UV-A sun beds. Livsstil, soling og bruning - hva med UV-A solarier

Energy Technology Data Exchange (ETDEWEB)

Thune, P [Ullevaal Sykehus, Oslo (Norway)

1991-06-01

This article considers the effects of ultraviolet (UV) light from the sun and UV-A sun beds on the skin. Sun worshipping and sun therapy has been en vogue for centuries, but in another way than used today. A changing lifestyle has led to an increase of various skin diseases, including skin cancer. Short wave UV-light (UV-B) in particular has been blamed for inducing not only erythema and pigmentation but also more chronic skin lesions. Long wave UV-light (UV-A) has been shown to be the cause of similar changes to the skin but the pigmentation is of another quality and affords less protection against the harmful effects of UV-B. A concept of sun reactive skin typing has been created. This is based on self-reported responses to an initial exposure to sun as regards tanning ability and erythema reaction. These two factors have certain practical consequences, not only for UV-phototherapy but also for a person's risk of developing skin cancer. Recently, several research groups and dermatologists have discouraged extensive use of UV-A sun beds because of side effects of varying degrees of seriousness. The possible implications of these side effects for the organism are not fully elucidated and may be more profound than known today. The British Photodermatology Group has issued more stringent rules for persons who, despite advice to the contrary, still wish to use UV-A sun beds. 14 refs., 1 tab.

Lifestyle, sun worshipping and sun tanning - what about UV-A sun beds. Livsstil, soling og bruning - hva med UV-A solarier

Energy Technology Data Exchange (ETDEWEB)

Thune, P. (Ullevaal Sykehus, Oslo (Norway))

1991-06-01

This article considers the effects of ultraviolet (UV) light from the sun and UV-A sun beds on the skin. Sun worshipping and sun therapy has been en vogue for centuries, but in another way than used today. A changing lifestyle has led to an increase of various skin diseases, including skin cancer. Short wave UV-light (UV-B) in particular has been blamed for inducing not only erythema and pigmentation but also more chronic skin lesions. Long wave UV-light (UV-A) has been shown to be the cause of similar changes to the skin but the pigmentation is of another quality and affords less protection against the harmful effects of UV-B. A concept of sun reactive skin typing has been created. This is based on self-reported responses to an initial exposure to sun as regards tanning ability and erythema reaction. These two factors have certain practical consequences, not only for UV-phototherapy but also for a person's risk of developing skin cancer. Recently, several research groups and dermatologists have discouraged extensive use of UV-A sun beds because of side effects of varying degrees of seriousness. The possible implications of these side effects for the organism are not fully elucidated and may be more profound than known today. The British Photodermatology Group has issued more stringent rules for persons who, despite advice to the contrary, still wish to use UV-A sun beds. 14 refs., 1 tab.

The effect of exposure to enhanced UV-B radiation on the penetration of monochromatic and polychromatic UV-B radiation in leaves of Brassica napus

International Nuclear Information System (INIS)

Cen, Y.-P.; Bornman, J.F.

1993-01-01

Using quartz optical fibres, penetration of both monochromatic (310 nm) and polychromatic UV-B (280–320 nm) radiation in leaves of Brassica napus L. (cv. Ceres) was measured. Plants were grown under either visible light (750 μmol m −2 s −1 photosynthetically active radiation) or with the addition of 8. 9 KJ m −2 day −1 biologically effective UV-B (UV-B BE ) radiation. Results showed that of the 310 nm radiation that penetreated the leaf, 90% was within the intial one third of the leaf with high attenuation in the leaf epidermis, especially in UV-treated plants. Polychromatic UV-B radiation, relative to incident radiation, showed a relatively uniform spectral distribution within the leaf, except for collimated radiation. Over 30% of the UV-screening pigments in the leaf, including flavonoids, were found in the adaxial epidermal layer, making this layer less transparent to UV-B radiation than the abaxial epidermis, which contained less than 12% of the UV-screening pigments. UV-screening pigments increased by 20% in UV-treated leaves relative to control leaves. Densely arranged epicuticular wax on the adaxial leaf surface of UV-treated plants may have further decreased penetration of UV-B radiation by reflectance. An increased leaf thickness, and decreases in leaf area and leaf dry weight were also found for UV-treated plants. (author)

Índice UV

Science.gov (United States)

Información general sobre el Índice UV que proporciona un pronóstico del riesgo esperado de sobreexposición a la radiación ultravioleta (UV) del sol. El índice UV va acompañado de recomendaciones para protegerse del sol.

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)

Numerical and experimental investigation of UV disinfection for water treatment

International Nuclear Information System (INIS)

Li, H.Y.; Osman, H.; Kang, C.W.; Ba, T.

2017-01-01

Highlights: • UV irradiation for water treatment is numerically and experimentally investigated. • Fluence rate E increases exponentially with the increase of UVT. • UV dose distribution moves to a high range with increase of UVT and lamp power. • A linear relationship is observed between fluence rate E and average UV dose D_a_v_e. • D_a_v_e decreases with the increase of UVT and fluid flow rate. - Abstract: Disinfection by ultraviolet (UV) for water treatment in a UV reactor is numerically and experimentally investigated in this paper. The flow of water, UV radiation transportation as well as microorganism particle trajectories in the UV reactor is simulated. The effects of different parameters including UV transmittance (UVT), lamp power and water flow rate on the UV dose distribution and average UV dose are studied. The UV reactor performance in terms of average UV dose under these parameters is analysed. Comparisons are made between experiments and simulations on the average UV dose and reasonable agreement is achieved. The results show that the fluence rate increases exponentially with the increase of UVT. The UV dose distribution profiles moves to a high range of UV dose with the increase of UVT and lamp power. The increase of water flow rate reduces the average exposure time of microorganism particles to the UV light, resulting in the shifting of UV dose distribution to a low range of UV dose. A linear relationship is observed between fluence rate and the average UV dose. The average UV dose increases with the increase of lamp power while it decreases with the increase of UVT and water flow rate.

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)

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)

Bystander Effect Induced by UV Radiation; why should we be interested? 

Directory of Open Access Journals (Sweden)

Maria Widel

2012-11-01

Full Text Available The bystander effect, whose essence is an interaction of cells directly subjected to radiation with adjacent non-subjected cells, via molecular signals, is an important component of ionizing radiation action. However, knowledge of the bystander effect in the case of ultraviolet (UV radiation is quite limited. Reactive oxygen and nitrogen species generated by UV in exposed cells induce bystander effects in non-exposed cells, such as reduction in clonogenic cell survival and delayed cell death, oxidative DNA damage and gene mutations, induction of micronuclei, lipid peroxidation and apoptosis. Although the bystander effect after UV radiation has been recognized in cell culture systems, its occurrence in vivo has not been studied. However, solar UV radiation, which is the main source of UV in the environment, may induce in human dermal tissue an inflammatory response and immune suppression, events which can be considered as bystander effects of UV radiation. The oxidative damage to DNA, genomic instability and the inflammatory response may lead to carcinogenesis. UV radiation is considered one of the important etiologic factors for skin cancers, basal- and squamous-cell carcinomas and malignant melanoma. Based on the mechanisms of actions it seems that the UV-induced bystander effect can have some impact on skin damage (carcinogenesis?, and probably on cells of other tissues. The paper reviews the existing data about the UV-induced bystander effect and discusses a possible implication of this phenomenon for health risk. 

Genomic and proteomic evidences unravel the UV-resistome of the poly-extremophile Acinetobacter sp. Ver3.

Science.gov (United States)

Kurth, Daniel; Belfiore, Carolina; Gorriti, Marta F; Cortez, Néstor; Farias, María E; Albarracín, Virginia H

2015-01-01

Ultraviolet radiation can damage biomolecules, with detrimental or even lethal effects for life. Even though lower wavelengths are filtered by the ozone layer, a significant amount of harmful UV-B and UV-A radiation reach Earth's surface, particularly in high altitude environments. high-altitude Andean lakes (HAALs) are a group of disperse shallow lakes and salterns, located at the Dry Central Andes region in South America at altitudes above 3,000 m. As it is considered one of the highest UV-exposed environments, HAAL microbes constitute model systems to study UV-resistance mechanisms in environmental bacteria at various complexity levels. Herein, we present the genome sequence of Acinetobacter sp. Ver3, a gammaproteobacterium isolated from Lake Verde (4,400 m), together with further experimental evidence supporting the phenomenological observations regarding this bacterium ability to cope with increased UV-induced DNA damage. Comparison with the genomes of other Acinetobacter strains highlighted a number of unique genes, such as a novel cryptochrome. Proteomic profiling of UV-exposed cells identified up-regulated proteins such as a specific cytoplasmic catalase, a putative regulator, and proteins associated to amino acid and protein synthesis. Down-regulated proteins were related to several energy-generating pathways such as glycolysis, beta-oxidation of fatty acids, and electronic respiratory chain. To the best of our knowledge, this is the first report on a genome from a polyextremophilic Acinetobacter strain. From the genomic and proteomic data, an "UV-resistome" was defined, encompassing the genes that would support the outstanding UV-resistance of this strain.

Genomic and proteomic evidences unravel the UV-resistome of the poly-extremophile Acinetobacter sp. Ver3

Directory of Open Access Journals (Sweden)

Daniel eKurth

2015-04-01

Full Text Available Ultraviolet radiation can damage biomolecules, with detrimental or even lethal effects for life. Even though lower wavelengths are filtered by the ozone layer, a significant amount of harmful UV-B and UV-A radiation reach Earth’s surface, particularly in high altitude environments. High-Altitude Andean Lakes (HAAL are a group of disperse shallow lakes and salterns, located at the Dry Central Andes region in South America at altitudes above 3,000 m. As it is considered one of the highest UV-exposed environments, HAAL microbes constitute model systems to study UV-resistance mechanisms in environmental bacteria at various complexity levels. Herein, we present the genome sequence of Acinetobacter sp. Ver3, a gammaproteobacterium isolated from Lake Verde (4,400 m, together with further experimental evidence supporting the phenomenological observations regarding this bacterium ability to cope with increased UV-induced DNA damage. Comparison with the genomes of other Acinetobacter strains highlighted a number of unique genes, such as a novel cryptochrome. Proteomic profiling of UV-exposed cells identified up-regulated proteins such as a specific cytoplasmic catalase, a putative regulator, and proteins associated to amino acid and protein synthesis. Down-regulated proteins were related to several energy-generating pathways such as glycolysis, beta-oxidation of fatty acids and electronic respiratory chain. To the best of our knowledge, this is the first report on a genome from a polyextremophilic Acinetobacter strain. From the genomic and proteomic data, an UV-resistome was defined, encompassing the genes that would support the outstanding UV-resistance of this strain.

Soil burial biodegradation studies of palm oil-based UV-curable films

Science.gov (United States)

Tajau, Rida; Salleh, Mek Zah; Salleh, Nik Ghazali Nik; Abdurahman, Mohamad Norahiman; Salih, Ashraf Mohammed; Fathy, Siti Farhana; Azman, Anis Asmi; Hamidi, Nur Amira

2016-01-01

The palm oil-based ultraviolet (uv)-curable films were subjected to an outdoor soil burial test to investigate the biodegradation under natural environment. The films were burial in the soil experiment plot at the Nuclear Malaysia's Dengkil complex. The uv-curable films were synthesized from the epoxidized palm oil acrylated (EPOLA) resin and the polyurethane palm oil (POBUA) resin, respectively. Biodegradation tests are more specific to burial film in soil experiments for 12 months under natural conditions. The biodegradability of palm oil resin based uv-curable films were investigated and compared with the petrochemical resin based film. The films properties were compared with respect to properties of the thermal characteristic, the crystallinity, the morphology and the weight loss which are analyzed using the thermogravimetric analysis (TGA), the differential scanning calorimetry (DSC), the scanning electron microscope (SEM), an optical microscope and the weight loss of film calculation. These findings suggested that the palm oil-based uv-curable films show quite satisfactory biodegradation levels.

Soil burial biodegradation studies of palm oil-based UV-curable films

International Nuclear Information System (INIS)

Tajau, Rida; Salleh, Mek Zah; Salleh, Nik Ghazali Nik; Abdurahman, Mohamad Norahiman; Salih, Ashraf Mohammed; Fathy, Siti Farhana; Azman, Anis Asmi; Hamidi, Nur Amira

2016-01-01

The palm oil-based ultraviolet (uv)-curable films were subjected to an outdoor soil burial test to investigate the biodegradation under natural environment. The films were burial in the soil experiment plot at the Nuclear Malaysia’s Dengkil complex. The uv-curable films were synthesized from the epoxidized palm oil acrylated (EPOLA) resin and the polyurethane palm oil (POBUA) resin, respectively. Biodegradation tests are more specific to burial film in soil experiments for 12 months under natural conditions. The biodegradability of palm oil resin based uv-curable films were investigated and compared with the petrochemical resin based film. The films properties were compared with respect to properties of the thermal characteristic, the crystallinity, the morphology and the weight loss which are analyzed using the thermogravimetric analysis (TGA), the differential scanning calorimetry (DSC), the scanning electron microscope (SEM), an optical microscope and the weight loss of film calculation. These findings suggested that the palm oil-based uv-curable films show quite satisfactory biodegradation levels

Soil burial biodegradation studies of palm oil-based UV-curable films

Energy Technology Data Exchange (ETDEWEB)

Tajau, Rida, E-mail: rida@nuclearmalaysia.gov.my; Salleh, Mek Zah, E-mail: mekzah@nuclearmalaysia.gov.my; Salleh, Nik Ghazali Nik, E-mail: nik-ghazali@nuclearmalaysia.gov.my; Abdurahman, Mohamad Norahiman, E-mail: iman5031@yahoo.com [Division of Radiation Processing Technology, Malaysia Nuclear Agency, Bangi, 43000 Kajang, Selangor (Malaysia); Salih, Ashraf Mohammed, E-mail: ashraf.msalih@gmail.com [Department of Radiation Processing, Sudan Atomic Energy Commission, Khartoum, 1111 Sudan (Sudan); Fathy, Siti Farhana, E-mail: farhana811@hotmail.com [Laboratory of Molecular Biomedicine, Institute of Bioscience (IBS), Universiti Putra Malaysia (UPM), 43400 UPM, Serdang, Selangor (Malaysia); Azman, Anis Asmi, E-mail: anisasmi18@gmail.com; Hamidi, Nur Amira, E-mail: amirahamidi93@yahoo.com [School of Chemical Sciences, Universiti Sains Malaysia (USM), 11800 USM, Pulau Pinang (Malaysia)

2016-01-22

The palm oil-based ultraviolet (uv)-curable films were subjected to an outdoor soil burial test to investigate the biodegradation under natural environment. The films were burial in the soil experiment plot at the Nuclear Malaysia’s Dengkil complex. The uv-curable films were synthesized from the epoxidized palm oil acrylated (EPOLA) resin and the polyurethane palm oil (POBUA) resin, respectively. Biodegradation tests are more specific to burial film in soil experiments for 12 months under natural conditions. The biodegradability of palm oil resin based uv-curable films were investigated and compared with the petrochemical resin based film. The films properties were compared with respect to properties of the thermal characteristic, the crystallinity, the morphology and the weight loss which are analyzed using the thermogravimetric analysis (TGA), the differential scanning calorimetry (DSC), the scanning electron microscope (SEM), an optical microscope and the weight loss of film calculation. These findings suggested that the palm oil-based uv-curable films show quite satisfactory biodegradation levels.

Comets in UV

Science.gov (United States)

Shustov, B.; Sachkov, M.; Gómez de Castro, A. I.; Vallejo, J. C.; Kanev, E.; Dorofeeva, V.

2018-04-01

Comets are important "eyewitnesses" of Solar System formation and evolution. Important tests to determine the chemical composition and to study the physical processes in cometary nuclei and coma need data in the UV range of the electromagnetic spectrum. Comprehensive and complete studies require additional ground-based observations and in situ experiments. We briefly review observations of comets in the ultraviolet (UV) and discuss the prospects of UV observations of comets and exocomets with space-borne instruments. A special reference is made to the World Space Observatory-Ultraviolet (WSO-UV) project.

Use of satellite erythemal UV products in analysing the global UV changes

Directory of Open Access Journals (Sweden)

I. Ialongo

2011-09-01

Full Text Available Long term changes in solar UV radiation affect global bio-geochemistry and climate. The satellite-based dataset of TOMS (Total Ozone Monitoring System and OMI (Ozone Monitoring Instrument of erythemal UV product was applied for the first time to estimate the long-term ultraviolet (UV changes at the global scale. The analysis of the uncertainty related to the different input information is presented. OMI and GOME-2 (Global Ozone Monitoring Experiment-2 products were compared in order to analyse the differences in the global UV distribution and their effect on the linear trend estimation.

The results showed that the differences in the inputs (mainly surface albedo and aerosol information used in the retrieval, affect significantly the UV change calculation, pointing out the importance of using a consistent dataset when calculating long term UV changes. The areas where these differences played a major role were identified using global maps of monthly UV changes. Despite the uncertainties, significant positive UV changes (ranging from 0 to about 5 %/decade were observed, with higher values in the Southern Hemisphere at mid-latitudes during spring-summer, where the largest ozone decrease was observed.

A simple way to an ultra-robust superhydrophobic fabric with mechanical stability, UV durability, and UV shielding property.

Science.gov (United States)

Ren, Guina; Song, Yuanming; Li, Xiangming; Wang, Bo; Zhou, Yanli; Wang, Yuyan; Ge, Bo; Zhu, Xiaotao

2018-07-15

Development of an ultra-robust superhydrophobic fabric with mechanical stability, UV durability, and UV shielding by a simple method is highly desirable, yet it remains a challenge that current technologies have been unable to fully address. Herein, the original fabric is immersed into the solution containing ZnO nanoparticle and PDMS (polydimethylsiloxane), and the fiber surfaces are uniformly covered by a ZnO-PDMS layer after thermal treatment at 110 °C for 30 min. Droplets of water and corrosive liquids including strong acid, strong alkali, and saturated salt solution display sphere shape on the ZnO-PDMS coated fabric surface. The stable binding of ZnO-PDMS layer onto the fibers allows for the fabric coating with robust superhydrophobicity, and the coated fabric still displays superhydrophobicity after hand twisting, knife scratching, finger touching, and even cycles of sandpaper abrasion. The ZnO-PDMS coated fabric can also keep its superhydrophobic property when exposed to long term UV illumination, demonstrating its UV resistance. Moreover, the uniformly distribution of ZnO nanoparticles on fibers allows the ZnO-PDMS coated fabric to display UV shielding property. Copyright © 2018 Elsevier Inc. All rights reserved.

Využití UV/VIS spektrofotometrie pro stanovení diklofenaku

Czech Academy of Sciences Publication Activity Database

Čapka, Lukáš; Zlámalová Gargošová, H.; Vávrová, M.; Urbánková, L.

2013-01-01

Roč. 107, č. 7 (2013), s. 550-554 ISSN 0009-2770 Institutional support: RVO:68081715 Keywords : diclofenac * UV-VIS spectrophotometry * environment * fate * pharmaceutical residues Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 0.196, year: 2013

UV-induced transcription from the human immunodeficiency virus type 1 (HIV-1) long terminal repeat and UV-induced secretion of an extracellular factor that induces HIV-1 transcription in nonirradiated cells

International Nuclear Information System (INIS)

Stein, B.; Kraemer, M.R.; Rahmsdorf, H.J.; Ponta, H.; Herrlich, P.

1989-01-01

UV irradiation, but not visible sunlight, induces the transcription of human immunodeficiency virus type 1 (HIV-1). Chimeric constructs carrying all or parts of the HIV-1 long terminal repeat linked to an indicator gene were transfected into HeLa cells or murine and human T-cell lines, and their response to irradiation was tested. The cis-acting element conferring UV responsiveness is identical to the sequence binding transcription factor NF kappa B. UV irradiation enhances NF kappa B binding activity as assayed by gel retardation experiments. Interestingly, the requirement for UV irradiation can be replaced by cocultivation of transfected cells with UV-irradiated nontransfected (HIV-1-negative) cells. A UV-induced extracellular protein factor is detected in the culture medium conditioned by UV-treated cells. The factor is produced upon UV irradiation by several murine and human cell lines, including HeLa, Molt-4, and Jurkat, and acts on several cells. These data suggest that the UV response of keratinocytes in human skin can be magnified and spread to deeper layers that are more shielded, including the Langerhans cells, and that this indirect UV response may contribute to the activation of HIV-1 in humans

PHYLOGENETIC ANALYSIS AND AUTECOLOGY OF SPORE-FORMING BACTERIA FROM HYPERSALINE ENVIRONMENTS.

Science.gov (United States)

Gladka, G V; Romanovskaya, V A; Tashyreva, H O; Tashyrev, O B

2015-01-01

Multi-resistant to extreme factors spore-forming bacteria of Bacillus genus are isolated from hypersaline environments of the Crimea (Ukraine) and the Dead Sea (Israel). Phylogenetic analysis showed distinction of dominating extremophilic culturable species in studied regions. In Crimean environments they are B. mojavensis and B. simplex, in the Dead Sea ecosystem--B. subtilis subsp. spizizenii, B. subtilis subsp. subtilis, B. licheniformis and B. simplex. Isolates are simultaneously halotolerant and resistant to UV radiation. Strains isolated from the Dead Sea and the Crimea environments were resistant to UV: LD90 and LD99.99 made 100-170 J/m2 and 750-1500 J/m2 respectively. Spores showed higher UV-resistance (LD99.99-2500 J/m2) than the vegetative cells. However the number of spores made 0.02-0.007% of the whole cell population, and should not significantly affect the UV LD99.99 value. Isolates of both environments were halotolerant in the range of 0.1-10% NaCl and thermotolerant in the range of 20-50 °C, and didn't grow at 15 °C. Survival strategy of spore-forming bacteria from hypersaline environments under high UV radiation level can be performed by spore formation which minimize cell damage as well as efficient DNA-repair systems that remove damages.

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

Dichotomy in response to indomethacin in uv-C and uv-B induced ultraviolet light inflammation

International Nuclear Information System (INIS)

Eaglstein, W.H.; Marsico, A.R.

1975-01-01

In subjects irradiated with both UV-C and UV-B ultraviolet light (UVL), 10 μg of intradermal indomethacin decreased the redness in all 13 of the UV-B irradiated areas but in only 2 of 13 of the UV-C irradiated areas. Higher doses of intradermal indomethacin (50 μg and 100 μg) decreased the redness produced by UV-C irradiation in 6 subjects. It is suggested that the failure of 10 μg of indomethacin to decrease the redness of the UV-C induced inflammation, while decreasing the redness in the UV-B induced inflammation, is consistent with the possibility that prostaglandins participate in UV-B but not UV-C induced inflammation

Effects of UV-B radiation on wax biosynthesis

International Nuclear Information System (INIS)

Barnes, J.; Paul, N.; Percy, K.; Broadbent, P.; McLaughlin, C.; Mullineaux, P.; Creissen, G.; Wellburn, A.

1994-01-01

Two genotypes of tobacco (Nicotiana tabacum L.) were exposed in controlled environment chambers to three levels of biologically effective ultraviolet-B radiation (UV-B BE ; 280-320nm): 0, 4.54 (ambient) and 5.66 (∼ 25% enhancement) kJ m -2 d -1 . After 28 days, the quantity of wax deposited on leaf surfaces was determined gravimetrically; epicuticular wax chemical composition was determined by capillary gas chromatography with homologue assignments confirmed by gas chromatography-mass spectrometry. Leaf wettability was assessed by measuring the contact angle of water droplets placed on leaf surfaces. Tobacco wax consisted of three major hydrocarbon classes: Straight-chain alkanes (C 27 -C 33 ) which comprised ∼ 59% of the hydrocarbon fraction, containing a predominance of odd-chain alkanes with C 31 as the most abundant homologue; branched-chain alkanes (C 25 -C 32 ) which comprised ∼38% of the hydrocarbon fraction with anteiso 3-methyltriacontane (C 30 ) as the predominant homologue; and fatty acids (C 14 -C 18 ) which comprised ∼ 3% of the wax. Exposure to enhanced UV-B radiation reduced the quantity of wax on the adaxial surface of the transgenic mutant, and resulted in marked changes in the chemical composition of the wax on the exposed leaf surface. Enhanced UV-B decreased the quantity of straight-chain alkanes, increased the quantity of branched-chain alkanes and fatty acids, and resulted in shifts toward shorter straight-chain lengths. Furthermore, UV-B-induced changes in wax composition were associated with increased wettability of tobacco leaf surfaces. Overall, the data are consistent with the view that UV-B radiation has a direct and fundamental effect on wax biosynthesis. Relationships between the physico-chemical nature of the leaf surface and sensitivity to UV-B radiation are discussed. (orig.)

Two-components UV-therapy

International Nuclear Information System (INIS)

Pullmann, H.; Steigleder, G.K.

1980-01-01

20 patients with generalized psoriasis were treated with an apparatus containing UV-A- and UV-B-fluorescence tubes to be switched separately. The therapy was started with an UV-A-dose of 12 J/cm 2 daily. After the first week of treatment UV-B in increasing doses was applicated additionally. Clearance was achieved in 80 percent. (orig.) [de

Ecotoxicological evaluation of four UV filters using marine organisms from different trophic levels Isochrysis galbana, Mytilus galloprovincialis, Paracentrotus lividus, and Siriella armata.

Science.gov (United States)

Paredes, E; Perez, S; Rodil, R; Quintana, J B; Beiras, R

2014-06-01

Due to the concern about the negative effects of exposure to sunlight, combinations of UV filters like 4-Methylbenzylidene-camphor (4-MBC), Benzophenone-3 (BP-3), Benzophenone-4 (BP-4) and 2-Ethylhexyl-4-methoxycinnamate (EHMC) are being introduced in all kind of cosmetic formulas. These chemicals are acquiring a concerning status due to their increasingly common use and the potential risk for the environment. The aim of this study is to assess the behaviour of these compounds in seawater, the toxicity to marine organisms from three trophic levels including autotrophs (Isochrysis galbana), herbivores (Mytilus galloprovincialis and Paracentrotus lividus) and carnivores (Siriella armata), and set a preliminary assessment of potential ecological risk of UV filters in coastal ecosystems. In general, EC50 results show that both EHMC and 4-MBC are the most toxic for our test species, followed by BP-3 and finally BP-4. The most affected species by the presence of these UV filters are the microalgae I. galbana, which showed toxicity thresholds in the range of μg L(-1) units, followed by S. armata>P. Lividus>M. galloprovincialis. The UV filter concentrations measured in the sampled beach water were in the range of tens or even hundreds of ng L(-1). The resulting risk quotients showed appreciable environmental risk in coastal environments for BP-3 and 4-MBC. Copyright © 2013 Elsevier Ltd. All rights reserved.

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.

Evaluating UV-C LED disinfection performance and ...

Science.gov (United States)

This study evaluated ultraviolet (UV) light emitting diodes (LEDs) emitting at 260 nm, 280 nm, and the combination of 260|280 nm together for their efficacy at inactivating Escherichia. coli, MS2 coliphage, human adenovirus type 2 (HAdV2), and Bacillus pumilus spores; research included an evaluation of genomic damage. Inactivation by the LEDs was compared with the efficacy of conventional UV sources, the low-pressure (LP) and medium-pressure (MP) mercury vapor lamps. The work also calculated the electrical energy per order of reduction of the microorganisms by the five UV sources.For E. coli, all five UV sources yielded similar inactivation rates. For MS2 coliphage, the 260 nm LED was most effective. For HAdV2 and B. pumilus, the MP UV lamp was significantly more effective than the LP UV and UVC LED sources. When considering electrical energy per order of reduction, the LP UV lamp was the most efficient for E. coli and MS2, and the MPUV and LPUV were equally efficient for HAdV2 and B. pumilus spores. Among the UVC LEDs, the 280 nm LED unit required the least energy per log reduction of E. coli and HAdV2. The 280 nm and 260|280 nm LED units were equally efficient per log reduction of B. pumilus spores, and the 260 nm LED unit required the lowest energy per order of reduction of MS2 coliphage. The combination of the 260 nm and 280 nm UV LED wavelengths was also evaluated for potential synergistic effects. No dual-wavelength synergy was detected for inactivation of

Estimation of surface UV levels based on Meteor-3/TOMS ozone data

Energy Technology Data Exchange (ETDEWEB)

Borisov, Y A [Central Aerological Observatory, Moscow (Russian Federation); Geogdzhaev, I V [Moscow Inst. of Physics and Technology, Moscow (Russian Federation); Khattatov, V U [Central Aerological Observatory, Moscow (Russian Federation)

1996-12-31

The major consequence of ozone layer depletion for the environment is an increase of harmful ultraviolet (UV) radiation on the Earth surface and in the upper ocean. This implies the importance of environmental UV monitoring. Since the direct global monitoring is not currently possible, indirect estimations of surface UV levels may be used based on satellite ozone data (Madronich, S. 1992). Total Ozone Mapping Spectrometer (TOMS) on board the METEOR-3 satellite provided regular set of data for such estimates. During the time of its operation (August, 1991 - December, 1994) the instrument registered several ozone hole events over Antarctica, when ozone levels dropped by as much as 60 % from their unperturbed values. Probably even more alarming ozone depletions were observed over highly populated regions of middle latitudes of northern hemisphere. Radiative transfer modeling was used to convert METEOR-3/TOMS daily ozone values into regional and global maps of biologically active UV. Calculations demonstrate the effect on surface UV levels produced by ozone hole over Antarctica and ozone depletions over the territory of Russia (March, 1994). UV contour lines deviate from the normal appearance which is determined by growing southward solar elevation. UV contour lines are almost perpendicular to the ozone ones in the ozone depletions areas. The 30 % ozone depletion, over Siberia caused more than 30 % increase in noontime erythemal UV levels, which is equivalent to 10-15 degrees southward latitude displacement. Higher UV radiation increases were found in ozone hole over South America (October 1992) equivalent to about 20 degrees southward displacement

Estimation of surface UV levels based on Meteor-3/TOMS ozone data

Energy Technology Data Exchange (ETDEWEB)

Borisov, Y.A. [Central Aerological Observatory, Moscow (Russian Federation); Geogdzhaev, I.V. [Moscow Inst. of Physics and Technology, Moscow (Russian Federation); Khattatov, V.U. [Central Aerological Observatory, Moscow (Russian Federation)

1995-12-31

The major consequence of ozone layer depletion for the environment is an increase of harmful ultraviolet (UV) radiation on the Earth surface and in the upper ocean. This implies the importance of environmental UV monitoring. Since the direct global monitoring is not currently possible, indirect estimations of surface UV levels may be used based on satellite ozone data (Madronich, S. 1992). Total Ozone Mapping Spectrometer (TOMS) on board the METEOR-3 satellite provided regular set of data for such estimates. During the time of its operation (August, 1991 - December, 1994) the instrument registered several ozone hole events over Antarctica, when ozone levels dropped by as much as 60 % from their unperturbed values. Probably even more alarming ozone depletions were observed over highly populated regions of middle latitudes of northern hemisphere. Radiative transfer modeling was used to convert METEOR-3/TOMS daily ozone values into regional and global maps of biologically active UV. Calculations demonstrate the effect on surface UV levels produced by ozone hole over Antarctica and ozone depletions over the territory of Russia (March, 1994). UV contour lines deviate from the normal appearance which is determined by growing southward solar elevation. UV contour lines are almost perpendicular to the ozone ones in the ozone depletions areas. The 30 % ozone depletion, over Siberia caused more than 30 % increase in noontime erythemal UV levels, which is equivalent to 10-15 degrees southward latitude displacement. Higher UV radiation increases were found in ozone hole over South America (October 1992) equivalent to about 20 degrees southward displacement

uv dye lasers

International Nuclear Information System (INIS)

Abakumov, G.A.; Fadeev, V.V.; Khokhlov, R.V.; Simonov, A.P.

1975-01-01

The most important property of visible dye lasers, that is, continuous wavelength tuning, stimulated the search for dyes capable to lase in uv. They were found in 1968. Now the need for tunable uv lasers for applications in spectroscopy, photochemistry, isotope separation, remote air and sea probing, etc. is clearly seen. A review of some recent advances in uv dye lasers is reviewed

New seismic instrumentation packaged for all terrestrial environments (including the quietest observatories!).

Science.gov (United States)

Parker, Tim; Devanney, Peter; Bainbridge, Geoff; Townsend, Bruce

2017-04-01

The march to make every type of seismometer, weak to strong motion, reliable and economically deployable in any terrestrial environment continues with the availability of three new sensors and seismic systems including ones with over 200dB of dynamic range. Until recently there were probably 100 pier type broadband sensors for every observatory type pier, not the types of deployments geoscientists are needing to advance science and monitoring capability. Deeper boreholes are now the recognized quieter environments for best observatory class instruments and these same instruments can now be deployed in direct burial environments which is unprecedented. The experiences of facilities in large deployments of broadband seismometers in continental scale rolling arrays proves the utility of packaging new sensors in corrosion resistant casings and designing in the robustness needed to work reliably in temporary deployments. Integrating digitizers and other sensors decreases deployment complexity, decreases acquisition and deployment costs, increases reliability and utility. We'll discuss the informed evolution of broadband pier instruments into the modern integrated field tools that enable economic densification of monitoring arrays along with supporting new ways to approach geoscience research in a field environment.

The effects of UV-B radiation on European heathland species

DEFF Research Database (Denmark)

Björn, Lars O.; Callaghan, T. V.; Johnsen, Ib

1997-01-01

in the ozone layer) with artificially increased precipitation. The Swedish experiment also involved a study of the interaction between enhanced UV-B radiation and elevated CO2 (600 ppm). These field studies were supported by an outdoor controlled environment study in the United Kingdom involving modulated...

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.

Space environment effects on polymers in low earth orbit

International Nuclear Information System (INIS)

Grossman, E.; Gouzman, I.

2003-01-01

Polymers are widely used in space vehicles and systems as structural materials, thermal blankets, thermal control coatings, conformal coatings, adhesives, lubricants, etc. The low earth orbit (LEO) space environment includes hazards such as atomic oxygen, UV radiation, ionizing radiation (electrons, protons), high vacuum, plasma, micrometeoroids and debris, as well as severe temperature cycles. Exposure of polymers and composites to the space environment may result in different detrimental effects via modification of their chemical, electrical, thermal, optical and mechanical properties as well as surface erosion. The high vacuum induces material outgassing (e.g. low-molecular weight residues, plasticizers and additives) and consequent contamination of nearby surfaces. The present work reviews the LEO space environment constituents and their interactions with polymers. Examples of degradation of materials exposed in ground simulation facilities are presented. The issues discussed include the erosion mechanisms of polymers, formation of contaminants and their interaction with the space environment, and protection of materials from the harsh space environment

The occurrence of UV filters in natural and drinking water in São Paulo State (Brazil).

Science.gov (United States)

da Silva, Claudia Pereira; Emídio, Elissandro Soares; de Marchi, Mary Rosa Rodrigues

2015-12-01

Ultraviolet (UV) filters are widely used in the formulation of personal care products (PCPs) to prevent damage to the skin, lips, and hair caused by excessive UV radiation. Therefore, large amounts of these substances are released daily into the aquatic environment through either recreational activities or the release of domestic sewage. The concern regarding the presence of such substances in the environment and the exposure of aquatic organisms is based on their potential for bioaccumulation and their potential as endocrine disruptors. Although there are several reports regarding the occurrence and fate of UV filters in the aquatic environment, these compounds are still overlooked in tropical areas. In this study, we investigated the occurrence of the organic UV filters benzophenone-3 (BP-3), ethylhexyl salicylate (ES), ethylhexyl methoxycinnamate (EHMC), and octocrylene (OC) in six water treatment plants in various cities in Southeast Brazil over a period of 6 months to 1 year. All of the UV filters studied were detected at some time during the sampling period; however, only EHMC and BP-3 were found in quantifiable concentrations, ranging from 55 to 101 and 18 to 115 ng L(-1), respectively. Seasonal variation of BP-3 was most clearly noticed in the water treatment plant in Araraquara, São Paulo, where sampling was performed for 12 months. BP-3 was not quantifiable in winter but was quantifiable in summer. The levels of BP-3 were in the same range in raw, treated and chlorinated water, indicating that the compound was not removed by the water treatment process.

/UV Synergistic Aging of Polyester Polyurethane Film Modified by Composite UV Absorber

Directory of Open Access Journals (Sweden)

Yanzhi Wang

2013-01-01

Full Text Available The pure polyester polyurethane (TPU film and the modified TPU (M-TPU film containing 2.0 wt.% inorganic UV absorbers mixture (nano-ZnO/CeO2 with weight ratio of 3 : 2 and 0.5 wt.% organic UV absorbers mixture (UV-531/UV-327 with weight ratio of 1 : 1 were prepared by spin-coating technique. The accelerated aging tests of the films exposed to constant UV radiation of 400 ± 20 µW/cm2 (313 nm with an ozone atmosphere of 100 ± 2 ppm were carried out by using a self-designed aging equipment at ambient temperature and relative humidity of 20%. The aging resistance properties of the films were evaluated by UV-Vis spectra, Fourier transform infrared spectra (FT-IR, photooxidation index, and carbonyl index analysis. The results show that the composite UV absorber has better protection for TPU system, which reduces distinctly the degradation of TPU film. O3/UV aging of the films increases with incremental exposure time. PI and CI of TPU and M-TPU films increase with increasing exposure time, respectively. PI and CI of M-TPU films are much lower than that of TPU film after the same time of exposure, respectively. Distinct synergistic aging effect exists between ozone aging and UV aging when PI and CI are used as evaluation index, respectively. Of course, the formula of these additives needs further improvement for industrial application.

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.

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.

Surface reflectance of Antarctic bryophytes and protection from UV and visible light

International Nuclear Information System (INIS)

Robinson, S.A.; Wasley, J.; Turnbull, J.

2000-01-01

Full text: As well as determining the amount of solar radiation available for photosynthesis, the surface reflectance and absorptance characteristics of plants are their first defence against damaging effects of solar radiation. The solar spectrum can be damaging to plants in many ways. At shorter wavelengths, UV-B (280-320 nm) radiation can cause lesions in nucleic acid and proteins. Excess levels of visible radiation (400-750) can cause photoinhibition whilst high absorbtance of longer wavelengths (>750) leads to increases in temperature that can be detrimental in some environments. The adaptation of surface reflectance properties of vascular plants to particular environments are well known in some ecosystems. For example in desert ecosystems pubescent leaf surfaces that increase reflectance are common and have been demonstrated to be important to protection from photoinhibition. The epidermal characteristics of some plants are also known to change in absorptance, due to the accumulation of specific compounds. For example flavonoids which are effective screens against UV-B radiation, increase upon exposure to UV-B radiation. In this study we surveyed the natural variability in surface reflectance in mosses growing in continental Antarctica. Antarctica is experiencing large increases in incident UV-B radiation due to reductions in concentrations of stratospheric ozone. Additionally over the summer months (November January), when moss is exposed to direct sunlight, levels of visible solar radiation are also high, increasing the likelihood of photoinhibitory damage in moss. Our aim in this study is to describe the natural variability in the surface reflectance characteristics of moss, such that we have a baseline with which to assess future changes in response to changes in global climate, and imposed experimental treatments, and also to develop hypotheses with respect to how mosses have adapted to the cold and arid antarctic environment. Variability in surface

UV-Vis spectroscopy of tyrosine side-groups in studies of protein structure. Part 2: selected applications.

Science.gov (United States)

Antosiewicz, Jan M; Shugar, David

2016-06-01

In Part 2 we discuss application of several different types of UV-Vis spectroscopy, such as normal, difference, and second-derivative UV absorption spectroscopy, fluorescence spectroscopy, linear and circular dichroism spectroscopy, and Raman spectroscopy, of the side-chain of tyrosine residues in different molecular environments. We review the ways these spectroscopies can be used to probe complex protein structures.

BIOCHEMICAL EFFECTS INDUCED BY UV TREATMENT ON 5 ROMANIAN PHASEOLUS VULGARIS L. CULTIVARS, GROWN IN FIELD

Directory of Open Access Journals (Sweden)

Iulia Bara

2006-08-01

Full Text Available Our study is focused on the influence of the UV-B irradiation, at the level of hidric balance, methabolic activity, and in the content of minerals, polyphenols, pigments, nucleic acids, proteins, of five romanian cultivars: Diva, Star, Vera, Ami, Avans of Phaseolus vulgaris, sawn after germination in enreached UV-B environment in natural field condition.

Occurrence of UV-absorbing, mycosporine-like compounds among cyanobacterial isolates and an estimate of their screening capacity

International Nuclear Information System (INIS)

Garcia-Pichel, F.; Castenholz, R.W.

1993-01-01

Many cyanobacteria inhabit environments with intense solar radiation. Among the mechanisms to prevent UV photodamage are negative photomovements and the synthesis of UV sunscreen compounds. To assess how common and diverse UV sunscreen substances are among cyanobacteria living under intense solar radiation, the researchers analysed isolates of cyanobacteria for mycosporine amino acids (MAAs)-like, UV-absorbing, water-soluable substances. The cellular locations and the effect of UV radiation on their specific contents were also investigated. MAAs are common but diverse among terrestrial cyanobacteria, most often occuring in species with extracellular scytonemin. The spectral complementation suggests that the combined action of scytonemin and MAA may be responsible for sunscreen effects at shorter UV wavelengths, while the effect at longer wavelenths must be due solely to scytonemin. The authors conclude that these compounds have a significant effect in preventing UV radiation damage. 34 refs., 2 figs., 4 tabs

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)

Tekstilde Uv Absorban Madde Uygulamaları The Applications of UV Absorber on Textiles

OpenAIRE

MERDAN, Nigar; ACAR, Kamil

2009-01-01

Tekstiller UV radyasyonuna karşı koruma sağlarken, bu aşamada radyasyonun dozu da önem taşımaktadır. Bu nedenle tekstil materyallerine UV absorban maddeler, liflerin üretimi esnasında ya da bitim işlemlerinde uygulanmaktadır. UV absorban maddelerin kullanılmasıyla, tekstil ürünlerinde UV ışınlarının geçirgenliğinin yoğunluk derecesi azaltılır. UV absorbanları, materyale gelen ışık tarafından oluşan olumsuz etkileri engeller

Poling of UV-written Waveguides

DEFF Research Database (Denmark)

Arentoft, Jesper; Kristensen, Martin; Hübner, Jörg

1999-01-01

We report poling of UV-written silica waveguides. Thermal poling induces an electro-optic coefficient of 0.05 pm/V. We also demonstrate simultaneous UV-writing and UV-poling. No measurable decay in the induced electro-optic effect was detected after nine months......We report poling of UV-written silica waveguides. Thermal poling induces an electro-optic coefficient of 0.05 pm/V. We also demonstrate simultaneous UV-writing and UV-poling. No measurable decay in the induced electro-optic effect was detected after nine months...

UV Spectroscopy of Metallic Asteroid (16) Psyche

Science.gov (United States)

Cunningham, N. J.; Becker, T. M.; Retherford, K. D.; Roth, L.; Feaga, L. M.; Wahlund, J.-E.; Elkins-Tanton, L. T.

2017-09-01

Asteroid (16) Psyche is the largest M-type asteroid, and the planned destination of the NASA Discovery mission Psyche and the proposed ESA M5 mission Heavy Metal. Psyche is considered to be the exposed core of a differentiated asteroid, whose mantle has been stripped by collisions; but other histories have been proposed. We observed Psyche with the Space Telescope Imaging Spectrograph (STIS) and Cosmic Origins Spectrograph (COS) aboard the Hubble Space Telescope, to obtain a full ultraviolet (UV) spectrum of both of Psyche's hemispheres. We seek to test three possible scenarios for Psyche's origin: Is Psyche the exposed core of a differentiated asteroid? Is it an asteroid with high olivine content that has been space-weathered? Or did Psyche accrete as-is in a highly-reducing environment early in the history of the solar system? We will present the UV spectra and their implications for Psyche's history.

Application of UV Imaging in Formulation Development.

Science.gov (United States)

Sun, Yu; Østergaard, Jesper

2017-05-01

Efficient drug delivery is dependent on the drug substance dissolving in the body fluids, being released from dosage forms and transported to the site of action. A fundamental understanding of the interplay between the physicochemical properties of the active compound and pharmaceutical excipients defining formulation behavior after exposure to the aqueous environments and pharmaceutical performance is critical in pharmaceutical development, manufacturing and quality control of drugs. UV imaging has been explored as a tool for qualitative and quantitative characterization of drug dissolution and release with the characteristic feature of providing real-time visualization of the solution phase drug transport in the vicinity of the formulation. Events occurring during drug dissolution and release, such as polymer swelling, drug precipitation/recrystallization, or solvent-mediated phase transitions related to the structural properties of the drug substance or formulation can be monitored. UV imaging is a non-intrusive and simple-to-operate analytical technique which holds potential for providing a mechanistic foundation for formulation development. This review aims to cover applications of UV imaging in the early and late phase pharmaceutical development with a special focus on the relation between structural properties and performance. Potential areas of future advancement and application are also discussed.

Prevention of the adverse photic effects of peripheral light-focusing using UV-blocking contact lenses.

Science.gov (United States)

Kwok, L Stephen; Kuznetsov, Valerian A; Ho, Arthur; Coroneo, Minas T

2003-04-01

Peripheral light-focusing (PLF) is an occult form of ultraviolet radiation (UVR) hazardous to the human eye. In PLF, obliquely incident light is refracted from the peripheral cornea to concentrated sites inside the anterior segment. In the current study, the directionality of this phenomenon for UVR and whether PLF is established in outdoor settings exposed to sunlight were investigated. The protection provided by a UV-blocking contact lens was also evaluated. UVA and UVB sensors were placed on the nasal limbus of an anatomically based model eye. The temporal limbus was exposed to a UV light source placed at various angles behind the frontal plane. PLF was quantified with the sensor output. The ensemble was mounted in the orbit of a mannequin head and exposed to sunlight in three insolation environments within the region of Sydney, Australia. PLF for UVA and UVB was determined with no eyewear or with sunglasses and commercially available soft contact lenses, with and without UV-blocking capability. The intensity of UVA peaked at approximately 120 degrees incidence, the level at which the UVB response was also at its maximum. The intensification of UVA was up to x18.3. The intensity of PLF for UVA and UVB was reduced by an order of magnitude by a UV-blocking contact lens, whereas a clear contact lenses had a much lesser effect. Only the UV-blocking contact lens achieved a significant effect on UVA and UVB irradiance in the urban, beach, and mountain locales (P UV-blocking soft contact lenses. Sunglasses may be unable to shield oblique rays, unless side protection is incorporated. Contact lenses can offer UVR protection against all angles of incidence, including the peak-response angle. They can also protect the eye in settings in which the wearing of sunglasses is not feasible or convenient.

Protective Role of Comfrey Leave Extracts on UV-induced Zebrafish Fin Damage.

Science.gov (United States)

Cheng, Chien-Chung; Chou, Chi-Yuan; Chang, Yao-Chin; Wang, Hsuan-Wen; Wen, Chi-Chung; Chen, Yau-Hung

2014-07-01

In zebrafish, UV exposure leads to fin malformation phenotypes including fin reduction or absence. The present study evaluated UV-protective activities of comfrey leaves extracts in a zebrafish model by recording fin morphological changes. Chemopreventive effects of comfrey leave extracts were evaluated using Kaplan-Meier analysis and Cox proportional hazards regression. The results showed that (1) the mean times of return to normal fin in the UV+comfrey (50 and 100 ppm) groups were 3.43 and 2.86 days and were quicker compared with that in the UV only group (4.21 days); (2) zebrafish fins in the UV+comfrey (50 and 100 ppm) groups were 2.05 and 3.25 times more likely to return to normal than those in the UV only group; and (3) comfrey leave extracts had UV-absorbance abilities and significantly reduced ROS production in UV-exposed zebrafish embryos, which may attenuate UV-mediated apoptosis. In conclusion, comfrey leaves extracts may have the potential to be developed as UV-protective agents to protect zebrafish embryos from UV-induced damage.

Standardization of UV LED measurements

Science.gov (United States)

Eppeldauer, G. P.; Larason, T. C.; Yoon, H. W.

2015-09-01

Traditionally used source spectral-distribution or detector spectral-response based standards cannot be applied for accurate UV LED measurements. Since the CIE standardized rectangular-shape spectral response function for UV measurements cannot be realized with small spectral mismatch when using filtered detectors, the UV measurement errors can be several times ten percent or larger. The UV LEDs produce broadband radiation and both their peaks or spectral bandwidths can change significantly. The detectors used for the measurement of these LEDs also have different spectral bandwidths. In the discussed example, where LEDs with 365 nm peak are applied for fluorescent crack-recognition using liquid penetrant (non-destructive) inspection, the broadband radiometric LED (signal) measurement procedure is standardized. A UV LED irradiance-source was calibrated against an FEL lamp standard to determine its spectral irradiance. The spectral irradiance responsivity of a reference UV meter was also calibrated. The output signal of the reference UV meter was calculated from the spectral irradiance of the UV source and the spectral irradiance responsivity of the reference UV meter. From the output signal, both the integrated irradiance (in the reference plane of the reference meter) and the integrated responsivity of the reference meter were determined. Test UV meters calibrated for integrated responsivity against the reference UV meter, can be used to determine the integrated irradiance from a field UV source. The obtained 5 % (k=2) measurement uncertainty can be decreased when meters with spectral response close to a constant value are selected.

UV light and urban pollution: bad cocktail for mosquitoes?

Science.gov (United States)

Tetreau, Guillaume; Chandor-Proust, Alexia; Faucon, Frédéric; Stalinski, Renaud; Akhouayri, Idir; Prud'homme, Sophie M; Régent-Kloeckner, Myriam; Raveton, Muriel; Reynaud, Stéphane

2014-01-01

Mosquito breeding sites consist of water pools, which can either be large open areas or highly covered ponds with vegetation, thus with different light exposures combined with the presence in water of xenobiotics including polycyclic aromatic hydrocarbons (PAHs) generated by urban pollution. UV light and PAHs are abiotic factors known to both affect the mosquito insecticide resistance status. Nonetheless, their potential combined effects on the mosquito physiology have never been investigated. The present article aims at describing the effects of UV exposure alongside water contamination with two major PAH pollutants (fluoranthene and benzo[a]pyrene) on a laboratory population of the yellow fever mosquito Aedes aegypti. To evaluate the effects of PAH exposure and low energetic UV (UV-A) irradiation on mosquitoes, different parameters were measured including: (1) The PAH localization and its impact on cell mortality by fluorescent microscopy; (2) The detoxification capacities (cytochrome P450, glutathione-S-transferase, esterase); (3) The responses to oxidative stress (Reactive Oxygen Species-ROS) and (4) The tolerance of mosquito larvae to a bioinsecticide (Bacillus thuringiensis subsp. israelensis-Bti) and to five chemical insecticides (DDT, imidacloprid, permethrin, propoxur and temephos). Contrasting effects regarding mosquito cell mortality, detoxification and oxidative stress were observed as being dependent on the pollutant considered, despite the fact that the two PAHs belong to the same family. Moreover, UV is able to modify pollutant effects on mosquitoes, including tolerance to three insecticides (imidacloprid, propoxur and temephos), cell damage and response to oxidative stress. Taken together, our results suggest that UV and pollution, individually or in combination, are abiotic parameters that can affect the physiology and insecticide tolerance of mosquitoes; but the complexity of their direct effect and of their interaction will require further

The protective roles of TiO2 nanoparticles against UV-B toxicity in Daphnia magna.

Science.gov (United States)

Liu, Jie; Wang, Wen-Xiong

2017-09-01

Aquatic environments are increasingly under environmental stress due to ultraviolet (UV) radiation and potential inputs of nanoparticles with intense application of nanotechnology. In this study, we investigated the interaction between UV-B radiation and titanium nanoparticles (TiO 2 -NPs) in a model freshwater cladoceran Daphnia magna. UV-B toxicity to Daphnia magna was examined when the daphnids were exposed to a range of TiO 2 -NPs concentrations with an initial 5 or 10min of 200μW/cm 2 UV-B radiation. In addition, UV-B toxicity was also examined in the presence of TiO 2 -NPs in the body of daphnids. Our results demonstrated that the daphnid mortality under UV-B radiation decreased significantly in the presence of TiO 2 -NPs both in the water and in the body, indicating that TiO 2 -NPs had some protective effects on D. magna against UV-B. Such protective effect was mainly caused by the blockage of UV-B by TiO 2 -NPs adsorption. UV-B produced reactive oxygen species (ROS) in the water and in the daphnids, which was not sufficient to cause mortality of daphnids over short periods of radiation. Previous studies focused on the effects of TiO 2 -NPs on the toxicity of total UV radiation, and did not attempt to differentiate the potential diverse roles of UV-A and UV-B. Our study indicated that TiO 2 -NPs may conversely protect the UV-B toxicity to daphnids. Copyright © 2017 Elsevier B.V. All rights reserved.

UV-indeks og dets betydning

DEFF Research Database (Denmark)

Wulf, Hans Christian; Eriksen, Paul

2010-01-01

The published UV index refers to the expected UV intensity at mid day, when the solar elevation is at its maximum. In Scandinavia, the maximum UV index is seven around midsummer. When the UV index is three, the erythema-weighted dose will be three Standard Erythema Dose (SED) in the hour with max...... a sunburn already when the UV index is higher than two....

Degradation of acrylamide by the UV/chlorine advanced oxidation process.

Science.gov (United States)

Gao, Ze-Chen; Lin, Yi-Li; Xu, Bin; Pan, Yang; Xia, Sheng-Ji; Gao, Nai-Yun; Zhang, Tian-Yang; Chen, Ming

2017-11-01

The degradation of acrylamide (AA) during UV/chlorine advanced oxidation process (AOP) was investigated in this study. The degradation of AA was negligible during UV irradiation alone. However, AA could be effectively degraded and mineralized during UV/chlorination due to the generation of hydroxyl radicals (OH). The degradation kinetics of AA during UV/chlorination fitted the pseudo-first order kinetics with the rate constant between AA and OH radicals being determined as 2.11 × 10 9  M -1  s -1 . The degradation rate and mineralization of AA during UV/chlorination were significantly promoted at acidic conditions as well as increasing chlorine dosage. The volatile degradation products of AA during UV/chlorination were identified using gas chromatography-mass spectrometry and the degradation pathways were then proposed accordingly. The formation of disinfection by-products (DBPs) in Milli-Q water and tap water during UV/chlorination of AA was also investigated. The DBPs included chloroform, dichloroacetonitrile, trichloroacetonitrile, 2,2-dichloroacetamide and 2,2,2-trichloroacetamide. Furthermore, the variations of AA degradation during UV/chlorination in different real water samples were evaluated. Copyright © 2017 Elsevier Ltd. All rights reserved.

UV-B and Mediterranean forest species: Direct effects and ecological consequences

International Nuclear Information System (INIS)

Paoletti, E.

2005-01-01

Experimental results from plants receiving elevated doses of UV-B radiation generally show that Mediterranean forest species are well protected against increases in UV-B radiation. Natural adaptations to water stress and excess light (elevated concentrations of UV-B screening compounds, leaf hairs, thick cuticle and epidermis), and UV-B responses (thickening of the cuticle, increase in carotenoids) may avoid or counter-balance UV-B radiation damage. This response confirms that Mediterranean forest vegetation is adapted to face oxidative stress factors, such as elevated tropospheric ozone concentrations, drought and high radiation, including UV-B. Nevertheless, in the long term, species-specific and season-specific differential responses in growth, physiology, phenology and reproductive behaviour may alter the interactions between species and lead to slow but important changes in ecosystem structure and function. - Mediterranean plant adaptations against water stress and excess light may also afford protection against UV-B

Femtosecond UV-laser pulses to unveil protein-protein interactions in living cells.

Science.gov (United States)

Itri, Francesco; Monti, Daria M; Della Ventura, Bartolomeo; Vinciguerra, Roberto; Chino, Marco; Gesuele, Felice; Lombardi, Angelina; Velotta, Raffaele; Altucci, Carlo; Birolo, Leila; Piccoli, Renata; Arciello, Angela

2016-02-01

A hallmark to decipher bioprocesses is to characterize protein-protein interactions in living cells. To do this, the development of innovative methodologies, which do not alter proteins and their natural environment, is particularly needed. Here, we report a method (LUCK, Laser UV Cross-linKing) to in vivo cross-link proteins by UV-laser irradiation of living cells. Upon irradiation of HeLa cells under controlled conditions, cross-linked products of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were detected, whose yield was found to be a linear function of the total irradiation energy. We demonstrated that stable dimers of GAPDH were formed through intersubunit cross-linking, as also observed when the pure protein was irradiated by UV-laser in vitro. We proposed a defined patch of aromatic residues located at the enzyme subunit interface as the cross-linking sites involved in dimer formation. Hence, by this technique, UV-laser is able to photofix protein surfaces that come in direct contact. Due to the ultra-short time scale of UV-laser-induced cross-linking, this technique could be extended to weld even transient protein interactions in their native context.

Kinetic removal of haloacetonitrile precursors by photo-based advanced oxidation processes (UV/H2O2, UV/O3, and UV/H2O2/O3).

Science.gov (United States)

Srithep, Sirinthip; Phattarapattamawong, Songkeart

2017-06-01

The objective of the study is to evaluate the performance of conventional treatment process (i.e., coagulation, flocculation, sedimentation and sand filtration) on the removals of haloacetonitrile (HAN) precursors. In addition, the removals of HAN precursors by photo-based advanced oxidation processes (Photo-AOPs) (i.e., UV/H 2 O 2 , UV/O 3 , and UV/H 2 O 2 /O 3 ) are investigated. The conventional treatment process was ineffective to remove HAN precursors. Among Photo-AOPs, the UV/H 2 O 2 /O 3 was the most effective process for removing HAN precursors, followed by UV/H 2 O 2 , and UV/O 3 , respectively. For 20min contact time, the UV/H 2 O 2 /O 3 , UV/H 2 O 2 , and UV/O 3 suppressed the HAN formations by 54, 42, and 27% reduction. Increasing ozone doses from 1 to 5 mgL -1 in UV/O 3 systems slightly improved the removals of HAN precursors. Changes in pH (6-8) were unaffected most of processes (i.e., UV, UV/H 2 O 2 , and UV/H 2 O 2 /O 3 ), except for the UV/O 3 system that its efficiency was low in the weak acid condition. The pseudo first-order kinetic constant for removals of dichloroacetonitrile precursors (k' DCANFP ) by the UV/H 2 O 2 /O 3 , UV/H 2 O 2 and standalone UV systems were 1.4-2.8 orders magnitude higher than the UV/O 3 process. The kinetic degradation of dissolved organic nitrogen (DON) tended to be higher than the k' DCANFP value. This study firstly differentiates the kinetic degradation between DON and HAN precursors. Copyright © 2017 Elsevier Ltd. All rights reserved.

Protective effects of polyamines against UV-A and UV-B illumination in Physcia semipinnata thalli

Directory of Open Access Journals (Sweden)

Esmer Işıl

2017-04-01

Full Text Available The damage to DNA induced by UV-A and UV-B and protective effects of the polyamines putrescine (put, spermidine (spd and spermine (spm were investigated on the lichen Physcia semipinnata in the present study. Our results suggest that significant alterations of the photosynthetic quantum yield ratio occurred in response to increased UV-A and UV-B exposure time. The photosynthetic quantum yield ratio gradually decreased in P. semipinnata following exposure to UV-A and UV-B. Physcia semipinnata thalli which were treated with a polyamine in a concentration of 1 mM were not affected by UV-A exposure for 72 h. In the case of UV-B treatment, the protective polyamine dosage was 0.25 mM. We also used the random amplified polymorphic DNA (RAPD technique to detect DNA damage. The main changes observed in the RAPD profiles, which were obtained using 12 RAPD primers, were the appearance or disappearance of different bands and variation of their intensities. The use of at least three different primers allowed detection of specific band patterns in both UV-A- and UV-B-exposed samples treated with polyamines as compared to untreated ones.

UV curing by radical, cationic and concurrent radicalcationic polymerization

International Nuclear Information System (INIS)

Pappas, S.P.

1984-01-01

UV and EB curing represent complementary technologies with respective advantages and disadvantages. This paper deals with the design and evaluation of UV curable coatings to optimize cure rate and film properties. Topics included are state-of-the-art photoinitiator systems, light intensity effects, retardation of air-inhibition, adhesion, and amplification of photons for enhanced speed of cure

Mechanistic Insight into the Degradation of Nitrosamines via Aqueous-Phase UV Photolysis or a UV-Based Advanced Oxidation Process: Quantum Mechanical Calculations.

Science.gov (United States)

Minakata, Daisuke; Coscarelli, Erica

2018-02-28

Nitrosamines are a group of carcinogenic chemicals that are present in aquatic environments that result from byproducts of industrial processes and disinfection products. As indirect and direct potable reuse increase, the presence of trace nitrosamines presents challenges to water infrastructures that incorporate effluent from wastewater treatment. Ultraviolet (UV) photolysis or UV-based advanced oxidation processes that produce highly reactive hydroxyl radicals are promising technologies to remove nitrosamines from water. However, complex reaction mechanisms involving radicals limit our understandings of the elementary reaction pathways embedded in the overall reactions identified experimentally. In this study, we perform quantum mechanical calculations to identify the hydroxyl radical-induced initial elementary reactions with N -nitrosodimethylamine (NDMA), N -nitrosomethylethylamine, and N -nitrosomethylbutylamine. We also investigate the UV-induced NDMA degradation mechanisms. Our calculations reveal that the alkyl side chains of nitrosamine affect the reaction mechanism of hydroxyl radicals with each nitrosamine investigated in this study. Nitrosamines with one- or two-carbon alkyl chains caused the delocalization of the electron density, leading to slower subsequent degradation. Additionally, three major initial elementary reactions and the subsequent radical-involved reaction pathways are identified in the UV-induced NDMA degradation process. This study provides mechanistic insight into the elementary reaction pathways, and a future study will combine these results with the kinetic information to predict the time-dependent concentration profiles of nitrosamines and their transformation products.

Mechanistic Insight into the Degradation of Nitrosamines via Aqueous-Phase UV Photolysis or a UV-Based Advanced Oxidation Process: Quantum Mechanical Calculations

Directory of Open Access Journals (Sweden)

Daisuke Minakata

2018-02-01

Full Text Available Nitrosamines are a group of carcinogenic chemicals that are present in aquatic environments that result from byproducts of industrial processes and disinfection products. As indirect and direct potable reuse increase, the presence of trace nitrosamines presents challenges to water infrastructures that incorporate effluent from wastewater treatment. Ultraviolet (UV photolysis or UV-based advanced oxidation processes that produce highly reactive hydroxyl radicals are promising technologies to remove nitrosamines from water. However, complex reaction mechanisms involving radicals limit our understandings of the elementary reaction pathways embedded in the overall reactions identified experimentally. In this study, we perform quantum mechanical calculations to identify the hydroxyl radical-induced initial elementary reactions with N-nitrosodimethylamine (NDMA, N-nitrosomethylethylamine, and N-nitrosomethylbutylamine. We also investigate the UV-induced NDMA degradation mechanisms. Our calculations reveal that the alkyl side chains of nitrosamine affect the reaction mechanism of hydroxyl radicals with each nitrosamine investigated in this study. Nitrosamines with one- or two-carbon alkyl chains caused the delocalization of the electron density, leading to slower subsequent degradation. Additionally, three major initial elementary reactions and the subsequent radical-involved reaction pathways are identified in the UV-induced NDMA degradation process. This study provides mechanistic insight into the elementary reaction pathways, and a future study will combine these results with the kinetic information to predict the time-dependent concentration profiles of nitrosamines and their transformation products.

Covalent dimerization of ribulose bisphosphate carboxylase subunits by UV radiation

Energy Technology Data Exchange (ETDEWEB)

Ferreira, R.M.B. [Universidade Tecnica, Lisbon (Portugal). Inst. Superior de Agronomia]|[Universidade Nova de Lisboa, Oeiras (Portugal). Instituto de Tecnologia Quimica e Biologica; Franco, E.; Teixeira, A.R.N. [Universidade Tecnica, Lisbon (Portugal). Inst. Superior de Agronomia

1996-08-15

The effect of UV radiation (UV-A, UV-B and UV-C) on ribulose bisphosphate carboxylase from a variety of plant species was examined. The exposition of plant leaves or the pure enzyme to UV radiation produced a UV-dependent accumulation of a 65 kDa polypeptide (P65). Different approaches were utilized to elucidate the origin and structure of P65: electrophoretic and fluorographic analyses of {sup 35}S-labelled ribulose biphosphate carboxylase exposed to UV radiation and immunological experiments using antibodies specific for P65, for the large and small subunits of ribulose biphosphate carboxylase and for high-molecular-mass aggregates of the enzyme. These studies revealed that P65 is a dimer, formed by the covalent, non-disulphide linkage of one small subunit with one large subunit of ribulose biphosphate carboxylase. For short periods of time (<1 h), the amount of P65 formed increased with the duration of the exposure to the UV radiation and with the energy of the radiation applied. Prolonged exposure to UV radiation (1-6 h) resulted in the formation of high-molecular-mass aggregates of ribulose biphosphate carboxylase. Formation of P65 was shown to depend on the native state of the protein, was stimulated by inhibitors of enzyme activity, and was inhibited by activators of enzyme activity. A UV-independent accumulation of P65 was also achieved by the in vitro incubation of plant crude extracts. However, the UV-dependent and the UV-independent formation of P65 seemed to occur by distinct molecular mechanisms. The UV-dependent accumulation of P65 was immunologically detected in all species examined, including Lemna minor, Arum italicum, Brassica oleracea, Triticum aestivum, Zea mays, Pisum sativum and Phaseolus vulgaris, suggesting that it may constitute a universal response to UV radiation, common to all photosynthetic tissues. (Author).

Covalent dimerization of ribulose bisphosphate carboxylase subunits by UV radiation

International Nuclear Information System (INIS)

Ferreira, R.M.B.; Universidade Nova de Lisboa, Oeiras; Franco, E.; Teixeira, A.R.N.

1996-01-01

The effect of UV radiation (UV-A, UV-B and UV-C) on ribulose bisphosphate carboxylase from a variety of plant species was examined. The exposition of plant leaves or the pure enzyme to UV radiation produced a UV-dependent accumulation of a 65 kDa polypeptide (P65). Different approaches were utilized to elucidate the origin and structure of P65: electrophoretic and fluorographic analyses of 35 S-labelled ribulose biphosphate carboxylase exposed to UV radiation and immunological experiments using antibodies specific for P65, for the large and small subunits of ribulose biphosphate carboxylase and for high-molecular-mass aggregates of the enzyme. These studies revealed that P65 is a dimer, formed by the covalent, non-disulphide linkage of one small subunit with one large subunit of ribulose biphosphate carboxylase. For short periods of time (<1 h), the amount of P65 formed increased with the duration of the exposure to the UV radiation and with the energy of the radiation applied. Prolonged exposure to UV radiation (1-6 h) resulted in the formation of high-molecular-mass aggregates of ribulose biphosphate carboxylase. Formation of P65 was shown to depend on the native state of the protein, was stimulated by inhibitors of enzyme activity, and was inhibited by activators of enzyme activity. A UV-independent accumulation of P65 was also achieved by the in vitro incubation of plant crude extracts. However, the UV-dependent and the UV-independent formation of P65 seemed to occur by distinct molecular mechanisms. The UV-dependent accumulation of P65 was immunologically detected in all species examined, including Lemna minor, Arum italicum, Brassica oleracea, Triticum aestivum, Zea mays, Pisum sativum and Phaseolus vulgaris, suggesting that it may constitute a universal response to UV radiation, common to all photosynthetic tissues. (Author)

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 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.

Energy Effectiveness of Direct UV and UV/H2O2 Treatment of Estrogenic Chemicals in Biologically Treated Sewage

Directory of Open Access Journals (Sweden)

Kamilla M. S. Hansen

2012-01-01

Full Text Available Continuous exposure of aquatic life to estrogenic chemicals via wastewater treatment plant effluents has in recent years received considerable attention due to the high sensitivity of oviparous animals to disturbances of estrogen-controlled physiology. The removal efficiency by direct UV and the UV/H2O2 treatment was investigated in biologically treated sewage for most of the estrogenic compounds reported in wastewater. The investigated compounds included parabens, industrial phenols, sunscreen chemicals, and steroid estrogens. Treatment experiments were performed in a flow through setup. The effect of different concentrations of H2O2 and different UV doses was investigated for all compounds in an effluent from a biological wastewater treatment plant. Removal effectiveness increased with H2O2 concentration until 60 mg/L. The treatment effectiveness was reported as the electrical energy consumed per unit volume of water treated required for 90% removal of the investigated compound. It was found that the removal of all the compounds was dependent on the UV dose for both treatment methods. The required energy for 90% removal of the compounds was between 28 kWh/m3 (butylparaben and 1.2 kWh/m3 (estrone for the UV treatment. In comparison, the UV/H2O2 treatment required between 8.7 kWh/m3 for bisphenol A and benzophenone-7 and 1.8 kWh/m3 for ethinylestradiol.

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)

Spectral slopes of the absorption coefficient of colored dissolved and detrital material inverted from UV-visible remote sensing reflectance.

Science.gov (United States)

Wei, Jianwei; Lee, Zhongping; Ondrusek, Michael; Mannino, Antonio; Tzortziou, Maria; Armstrong, Roy

2016-03-01

The spectral slope of the absorption coefficient of colored dissolved and detrital material (CDM), S cdm (units: nm -1 ), is an important optical parameter for characterizing the absorption spectral shape of CDM. Although highly variable in natural waters, in most remote sensing algorithms, this slope is either kept as a constant or empirically modeled with multiband ocean color in the visible domain. In this study, we explore the potential of semianalytically retrieving S cdm with added ocean color information in the ultraviolet (UV) range between 360 and 400 nm. Unique features of hyperspectral remote sensing reflectance in the UV-visible wavelengths (360-500 nm) have been observed in various waters across a range of coastal and open ocean environments. Our data and analyses indicate that ocean color in the UV domain is particularly sensitive to the variation of the CDM spectral slope. Here, we used a synthesized data set to show that adding UV wavelengths to the ocean color measurements will improve the retrieval of S cdm from remote sensing reflectance considerably, while the spectral band settings of past and current satellite ocean color sensors cannot fully account for the spectral variation of remote sensing reflectance. Results of this effort support the concept to include UV wavelengths in the next generation of satellite ocean color sensors.

Evaluation of UV-permeability and photo-oxidisability of organic ultraviolet radiation-absorbing coatings

Energy Technology Data Exchange (ETDEWEB)

Li, Neng; Chen, Yuhe, E-mail: yuhec@sina.com; Bao, Yongjie; Zhang, Zeqian; Wu, Zaixing; Chen, Zhangmin

2015-03-30

Highlights: • We investigate organic UV radiation-absorbing coatings for use on bamboo surfaces. • The size of glass exactly inserted into sample cell of UV-Vis spectrophotometer. • A model was made to predict UV absorption of coatings. • We examine carbonyl groups change of coatings after ageing. • Two formulations which could effectively protect coating were obtained. - Abstract: Enhancing the durability of the coatings used on bamboo products is essential for increasing their use in outdoor environments. In this study, we investigated organic UV radiation-absorbing coatings for use on bamboo surfaces. The degree of resistance of the coatings, which contained 2-(2-hydroxy-3-tert-butyl-5-methyl-phenyl)-5-chlorinated benzotriazole (BTZ-1), to UV radiation degradation was determined through spectroscopic analysis. The critical BTZ-1 loading amount was determined by analysing the spectroscopic data. Fourier transform infrared spectroscopy was used to elucidate the relationship between the degree of photooxidation of the coatings and their BTZ-1 concentration. The experimental results showed that the coatings provided a high degree of shielding from UV radiation. The critical loading amount was determined to be 1.82 ± 0.05 g BTZ-1/m{sup 2}. The coatings formed using the formulations that contained 3 and 5 wt% BTZ-1 exhibited the lowest degree of photooxidation after exposure to UV radiation.

Airborne pipeline leak detection: UV or IR?

Science.gov (United States)

Babin, François; Gravel, Jean-François; Allard, Martin

2016-05-01

This paper presents a study of different approaches to the measurement of the above ground vapor plume created by the spill caused by a small 0.1 l/min (or less) leak in an underground liquid petroleum pipeline. The scenarios are those for the measurement from an airborne platform. The usual approach is that of IR absorption, but in the case of liquid petroleum products, there are drawbacks that will be discussed, especially when using alkanes to detect a leak. The optical measurements studied include UV enhanced Raman lidar, UV fluorescence lidar and IR absorption path integrated lidars. The breadboards used for testing the different approaches will be described along with the set-ups for leak simulation. Although IR absorption would intuitively be the most sensitive, it is shown that UV-Raman could be an alternative. When using the very broad alkane signature in the IR, the varying ground spectral reflectance are a problem. It is also determined that integrated path measurements are preferred, the UV enhanced Raman measurements showing that the vapor plume stays very close to the ground.

Single Photon Counting UV Solar-Blind Detectors Using Silicon and III-Nitride Materials

Science.gov (United States)

Nikzad, Shouleh; Hoenk, Michael; Jewell, April D.; Hennessy, John J.; Carver, Alexander G.; Jones, Todd J.; Goodsall, Timothy M.; Hamden, Erika T.; Suvarna, Puneet; Bulmer, J.; Shahedipour-Sandvik, F.; Charbon, Edoardo; Padmanabhan, Preethi; Hancock, Bruce; Bell, L. Douglas

2016-01-01

Ultraviolet (UV) studies in astronomy, cosmology, planetary studies, biological and medical applications often require precision detection of faint objects and in many cases require photon-counting detection. We present an overview of two approaches for achieving photon counting in the UV. The first approach involves UV enhancement of photon-counting silicon detectors, including electron multiplying charge-coupled devices and avalanche photodiodes. The approach used here employs molecular beam epitaxy for delta doping and superlattice doping for surface passivation and high UV quantum efficiency. Additional UV enhancements include antireflection (AR) and solar-blind UV bandpass coatings prepared by atomic layer deposition. Quantum efficiency (QE) measurements show QE > 50% in the 100–300 nm range for detectors with simple AR coatings, and QE ≅ 80% at ~206 nm has been shown when more complex AR coatings are used. The second approach is based on avalanche photodiodes in III-nitride materials with high QE and intrinsic solar blindness. PMID:27338399

Comparative investigation of X-ray contrast medium degradation by UV/chlorine and UV/H2O2.

Science.gov (United States)

Kong, Xiujuan; Jiang, Jin; Ma, Jun; Yang, Yi; Pang, Suyan

2018-02-01

The degradation of iopamidol and diatrizoate sodium (DTZ) by UV/chlorine was carried out according to efficiency, mechanism, and oxidation products, and compared to that by UV/H 2 O 2 . The pseudo-first order rate (k') of iopamidol and DTZ was accelerated by UV/chlorine compared to that by UV and chlorine alone. k' of iopamidol and DTZ by UV/chlorine increased with increasing chlorine dosage. Both of iopamidol and DTZ could not be effectively removed by UV/H 2 O 2 compared to that by UV/chlorine. Secondary radicals (Cl 2 - and ClO) rather than primary radicals (HO and Cl) were demonstrated to be mainly responsible for the enhanced removal of iopamidol and DTZ by UV/chlorine. The oxidation products of iopamidol and DTZ resulting from UV/chlorine and UV/H 2 O 2 process were identified, and differences existed in the two systems. IO 3 - (the desired sink of I - ) was the major inorganic product in the UV/chlorine process whereas I - was the predominant inorganic product in the UV/H 2 O 2 process. The formation of chlorine-containing products during the degradation of iopamidol and DTZ by UV/chlorine was also observed. H-abstraction, additions, de-iodination were shared during the degradation of iopamidol by UV/chlorine and UV/H 2 O 2 . Neutral pH condition was preferred for the removal of iopamidol and DTZ by UV/chlorine. UV/chlorine could also be applied in real waters for the removal of iopamidol and DTZ. Copyright © 2017 Elsevier Ltd. All rights reserved.

Inhibitory effects of ambient levels of solar UV-A and UV-B radiation on growth of cucumber

International Nuclear Information System (INIS)

Krizek, D.T.; Mirecki, R.M.; Britz, S.J.

1997-01-01

The influence of solar UV-A and UV-B radiation at Beltsville, Maryland, on growth and flavonoid content in four cultivars of Cucumis sativus L. (Ashley, Poinsett, Marketmore, and Salad Bush cucumber) was examined during the summers of 1994 and 1995. Plants were grown from seed in UV exclusion chambers consisting of UV-transmitting Plexiglas, lined with Llumar to exclude UV-A and UV-B, polyester to exclude UV-B, or cellulose acetate to transmit UV-A and UV-B. Despite previously determined differences in sensitivity to supplemental UV-B radiation, all four cultivars responded similarly to UV-B exclusion treatment. After 19–21 days, the four cultivars grown in the absence of solar UV-B (polyester) had an average of 34, 55, and 40% greater biomass of leaves, stems, and roots, respectively, 27% greater stem height, and 35% greater leaf area than those grown under ambient UV-B (cellulose acetate). Plants protected from UV-A radiation as well (Llumar) showed an additional 14 and 22% average increase, respectively, in biomass of leaves and stems, and a 22 and 19% average increase, respectively, in stem elongation and leaf area over those grown under polyester. These findings demonstrate the extreme sensitivity of cucumber not only to present levels of UV-B but also to UV-A and suggest that even small changes in ozone depletion may have important biological consequences for certain plant species. (author)

Light scattering on PHA granules protects bacterial cells against the harmful effects of UV radiation.

Science.gov (United States)

Slaninova, Eva; Sedlacek, Petr; Mravec, Filip; Mullerova, Lucie; Samek, Ota; Koller, Martin; Hesko, Ondrej; Kucera, Dan; Marova, Ivana; Obruca, Stanislav

2018-02-01

Numerous prokaryotes accumulate polyhydroxyalkanoates (PHA) in the form of intracellular granules. The primary function of PHA is the storage of carbon and energy. Nevertheless, there are numerous reports that the presence of PHA granules in microbial cells enhances their stress resistance and fitness when exposed to various stress factors. In this work, we studied the protective mechanism of PHA granules against UV irradiation employing Cupriavidus necator as a model bacterial strain. The PHA-accumulating wild type strain showed substantially higher UV radiation resistance than the PHA non-accumulating mutant. Furthermore, the differences in UV-Vis radiation interactions with both cell types were studied using various spectroscopic approaches (turbidimetry, absorption spectroscopy, and nephelometry). Our results clearly demonstrate that intracellular PHA granules efficiently scatter UV radiation, which provides a substantial UV-protective effect for bacterial cells and, moreover, decreases the intracellular level of reactive oxygen species in UV-challenged cells. The protective properties of the PHA granules are enhanced by the fact that granules specifically bind to DNA, which in turn provides shield-like protection of DNA as the most UV-sensitive molecule. To conclude, the UV-protective action of PHA granules adds considerable value to their primary storage function, which can be beneficial in numerous environments.

UV-MAOR - UV-B-specific reactions of marine planktons. Final report

International Nuclear Information System (INIS)

Gerbersdorf, S.; Steeger, H.U.; Schubert, H.; Paul, R.J.

2001-02-01

An initial finding of the studies performed here is that under certain hydrogeographic and meteorological conditions vertical migration of phyto and zooplankton also occurs in near-shore parts of flat waters. The vertical migration of phytoplankton was induced by exceeding the threshold intensity of approx. 300 μmol photons m -2 s -1 (PAR). However, the sigmoidal course of the reaction of phytoplankton suggests that it is apparently not the PAR intensity alone but the ratio of PAR/UV-B which governs the downward migration. However, the present body of data is not sufficient for a definitive statistical verification of this finding. Light irradiation resulted in an increased density and thus in a reduced buoyancy of flounder spawn. This effect was primarily dependent on intensity and did not increase upon irradiation with UV-B, UV-A and PAR as compared to UV-A and PAR alone. Irradiation with UV-B did not influence the substance located in the vitellus whose absorption maximum was found to be 300 nm, probably gadusol

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)

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

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.

Sunscreen for fish: co-option of UV light protection for camouflage.

Directory of Open Access Journals (Sweden)

Kaspar P Mueller

Full Text Available Many animals change their body pigmentation according to illumination of their environment. In aquatic vertebrates, this reaction is mediated through aggregation or dispersion of melanin-filled vesicles (melanosomes in dermal pigment cells (melanophores. The adaptive value of this behavior is usually seen in camouflage by allowing the animal to visually blend into the background. When exposed to visible light from below, however, dark-adapted zebrafish embryos at the age of 2 days post fertilization (dpf surprisingly display dispersal instead of aggregation of melanosomes, i.e. their body coloration becomes dark on a bright background. Melanosomes of older embryos and early larvae (3-5 dpf on the other hand aggregate as expected under these conditions. Here we provide an explanation to this puzzling finding: Melanosome dispersion in larvae 3 dpf and older is efficiently triggered by ultraviolet (UV light, irrespective of the visual background, suggesting that the extent of pigmentation is a trade-off between threats from predation and UV irradiation. The UV light-induced dispersion of melanosomes thereby is dependent on input from retinal short wavelength-sensitive (SWS cone photoreceptors. In young embryos still lacking a functional retina, protection from UV light predominates, and light triggers a dispersal of melanosomes via photoreceptors intrinsic to the melanophores, regardless of the actual UV content. In older embryos and early larvae with functional retinal photoreceptors in contrast, this light-induced dispersion is counteracted by a delayed aggregation in the absence of UV light. These data suggest that the primary function of melanosome dispersal has evolved as a protective adaption to prevent UV damage, which was only later co-opted for camouflage.

Sunscreen for Fish: Co-Option of UV Light Protection for Camouflage

Science.gov (United States)

Mueller, Kaspar P.; Neuhauss, Stephan C. F.

2014-01-01

Many animals change their body pigmentation according to illumination of their environment. In aquatic vertebrates, this reaction is mediated through aggregation or dispersion of melanin-filled vesicles (melanosomes) in dermal pigment cells (melanophores). The adaptive value of this behavior is usually seen in camouflage by allowing the animal to visually blend into the background. When exposed to visible light from below, however, dark-adapted zebrafish embryos at the age of 2 days post fertilization (dpf) surprisingly display dispersal instead of aggregation of melanosomes, i.e. their body coloration becomes dark on a bright background. Melanosomes of older embryos and early larvae (3–5 dpf) on the other hand aggregate as expected under these conditions. Here we provide an explanation to this puzzling finding: Melanosome dispersion in larvae 3 dpf and older is efficiently triggered by ultraviolet (UV) light, irrespective of the visual background, suggesting that the extent of pigmentation is a trade-off between threats from predation and UV irradiation. The UV light-induced dispersion of melanosomes thereby is dependent on input from retinal short wavelength-sensitive (SWS) cone photoreceptors. In young embryos still lacking a functional retina, protection from UV light predominates, and light triggers a dispersal of melanosomes via photoreceptors intrinsic to the melanophores, regardless of the actual UV content. In older embryos and early larvae with functional retinal photoreceptors in contrast, this light-induced dispersion is counteracted by a delayed aggregation in the absence of UV light. These data suggest that the primary function of melanosome dispersal has evolved as a protective adaption to prevent UV damage, which was only later co-opted for camouflage. PMID:24489905

Selection in vitro for UV-tolerant sugar beet (Beta vulgaris) somaclones

International Nuclear Information System (INIS)

Levall, M.W.; Bornman, J.F.

1993-01-01

With a reduced stratospheric ozone concentration, the generation of UV-tolerant plants may be of particular importance. Among different crop plants there is large variation in sensitivity to UV-B radiation. This study was undertaken to investigate the possibilities of using somaclonal variation and selection in vitro for improving UV-B tolerance in sugar beet (Beta vulgaris L.). Sugar beet callus was exposed to UV radiation (280–320 nm, 0.863–5.28 kJ m -2 day -1 , unweighted) and resultant shoots were selected from surviving cells. After establishment of the plants, they were grown under either visible radiation (114 μmol m -2 s -1 PAR) or with the addition of UV radiation (6.3 kJ m -2 day -1 biologically effective UV-B). Screening of regenerants in vivo for tolerance to UV radiation was undertaken 10 months after termination of the UV selection pressure. Screening was done visually and by using a number of physiological parameters, including chlorophyll fluorescence induction, ultraweak luminescence, pigment analysis and total content of UV-screening pigments. A clear difference between the unselected and the UV-selected somaclones was observed when visually studying the UV damage and other leaf injury. The observations were supported by the ultraweak luminescence measurements. Unselected plants showed significantly greater damage when subjected to subsequent UV radiation as compared to the selected plants. The clones subjected to UV selection pressure displayed a significantly higher concentration of UV-screening pigments under subsequent UV radiation. The unselected plants under subsequent UV treatment showed a lower carotenoid concentration when compared to selected plants. However, no significant difference between treatments was found for chlorophyll a/b, or F/Fmax, a measure of photosynthetic quantum yield

UV radiation and its effects. Proceedings

International Nuclear Information System (INIS)

1993-01-01

The National Science Strategy Committee for Climate Change was established in 1991 by the New Zealand Minister of Research, Science and Technology. It advises government through the Minister on research priorities and on levels of expenditure appropriate in various topics relating to climate change. An additional role is to promote coordination between research groups and the user communities to ensure an appropriate range of research strategies. To assist with implementing the latter aspects the NSS Committee will organise workshops on specific aspects of atmosphere and climate change, with a broad spectrum of participants. The first of these was the Workshop on UV Radiation and its Effects held in Christchurch on 20-21 May 1993. The workshop had 40 participants, including representatives from specialist science groups, medicine, veterinary science, farming, forestry and environmental groups. This publication will update the interested reader, whether scientist or lay-person, on the current state of knowledge on changing UV radiation levels and potential problems. As the summaries of papers show, research on ozone levels and on UV radiation and its effects is particularly appropriate for New Zealand scientists with their access to sites covering a wide range of latitudes from Antarctica to the Pacific Islands. New Zealand is part of an important international monitoring network, measuring local stratospheric ozone levels and related surface UV radiation levels. There are concerns about increasing UVB levels and the consequent effects on human health, plant and tree growth, and phytoplankton growth in the oceans. Priorities for further work on these areas are included in the summary of the workshop. (author). 13 figs.; 5 tabs

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

Solar UV exposure among outdoor workers in Denmark measured with personal UV-B dosimeters

DEFF Research Database (Denmark)

Grandahl, Kasper; Mortensen, Ole Steen; Sherman, David Zim

2017-01-01

radiation exposure are needed to help resolve this problem. This can be done using personal ultraviolet radiation dosimeters. Methods: We consider technical and practical feasibility of measuring individual solar ultraviolet exposure at work and leisure in professions with different á priori temporal high......-level outdoor worktime, using aluminium gallium nitride (AlGaN) photodiode detector based personal UV-B dosimeters. Essential technical specifications including the spectral and angular responsivity of the dosimeters are described and pre-campaign dosimeter calibration applicability is verified. The scale...... with our specialist knowledge as occupational physicians. Conclusions: Large-scale use of personal UV-B dosimeters for measurement of solar ultraviolet radiation exposure at work and leisure in Denmark is indeed feasible from a technical and practical viewpoint. Samples of exposure data shown support...

Listeria monocytogenes behaviour in presence of non-UV-irradiated titanium dioxide nanoparticles.

Directory of Open Access Journals (Sweden)

Maria Grazia Ammendolia

Full Text Available Listeria monocytogenes is the agent of listeriosis, a food-borne disease. It represents a serious problem for the food industry because of its environmental persistence mainly due to its ability to form biofilm on a variety of surfaces. Microrganisms attached on the surfaces are a potential source of contamination for environment and animals and humans. Titanium dioxide nanoparticles (TiO2 NPs are used in food industry in a variety of products and it was reported that daily exposure to these nanomaterials is very high. Anti-listerial activity of TiO2 NPs was investigated only with UV-irradiated nanomaterials, based on generation of reactive oxigen species (ROS with antibacterial effect after UV exposure. Since both Listeria monocytogenes and TiO2 NPs are veicolated with foods, this study explores the interaction between Listeria monocytogenes and non UV-irradiated TiO2 NPs, with special focus on biofilm formation and intestinal cell interaction. Scanning electron microscopy and quantitative measurements of biofilm mass indicate that NPs influence both production and structural architecture of listerial biofilm. Moreover, TiO2 NPs show to interfere with bacterial interaction to intestinal cells. Increased biofilm production due to TiO2 NPs exposure may favour bacterial survival in environment and its transmission to animal and human hosts.

UV-induced DNA-binding proteins in human cells

International Nuclear Information System (INIS)

Glazer, P.M.; Greggio, N.A.; Metherall, J.E.; Summers, W.C.

1989-01-01

To investigate the response of human cells to DNA-damaging agents such as UV irradiation, the authors examined nuclear protein extracts of UV-irradiated HeLa cells for the presence of DNA-binding proteins. Electrophoretically separated proteins were transferred to a nitrocellulose filter that was subsequently immersed in a binding solution containing radioactively labeled DNA probes. Several DNA-binding proteins were induced in HeLa cells after UV irradiation. These included proteins that bind predominantly double-stranded DNA and proteins that bind both double-stranded and single-stranded DNA. The binding proteins were induced in a dose-dependent manner by UV light. Following a dose of 12 J/m 2 , the binding proteins in the nuclear extracts increased over time to a peak in the range of 18 hr after irradiation. Experiments with metabolic inhibitors (cycloheximide and actinomycin D) revealed that de novo synthesis of these proteins is not required for induction of the binding activities, suggesting that the induction is mediated by protein modification

Validation of an Innovative Satellite-Based UV Dosimeter

Science.gov (United States)

Morelli, Marco; Masini, Andrea; Simeone, Emilio; Khazova, Marina

2016-08-01

We present an innovative satellite-based UV (ultraviolet) radiation dosimeter with a mobile app interface that has been validated by exploiting both ground-based measurements and an in-vivo assessment of the erythemal effects on some volunteers having a controlled exposure to solar radiation.Both validations showed that the satellite-based UV dosimeter has a good accuracy and reliability needed for health-related applications.The app with this satellite-based UV dosimeter also includes other related functionalities such as the provision of safe sun exposure time updated in real-time and end exposure visual/sound alert. This app will be launched on the global market by siHealth Ltd in May 2016 under the name of "HappySun" and available both for Android and for iOS devices (more info on http://www.happysun.co.uk).Extensive R&D activities are on-going for further improvement of the satellite-based UV dosimeter's accuracy.

Challenges of UV light processing of low UVT foods and beverages

Science.gov (United States)

Koutchma, Tatiana

2010-08-01

Ultraviolet (UV) technology holds promise as a low cost non-thermal alternative to heat pasteurization of liquid foods and beverages. However, its application for foods is still limited due to low UV transmittance (LUVT). LUVT foods have a diverse range of chemical (pH, Brix, Aw), physical (density and viscosity) and optical properties (absorbance and scattering) that are critical for systems and process designs. The commercially available UV sources tested for foods include low and medium pressure mercury lamps (LPM and MPM), excimer and pulsed lamps (PUV). The LPM and excimer lamps are monochromatic sources whereas emission of MPM and PUV is polychromatic. The optimized design of UV-systems and UV-sources with parameters that match to specific product spectra have a potential to make UV treatments of LUVT foods more effective and will serve its further commercialization. In order to select UV source for specific food application, processing effects on nutritional, quality, sensorial and safety markers have to be evaluated. This paper will review current status of UV technology for food processing along with regulatory requirements. Discussion of approaches and results of measurements of chemico-physical and optical properties of various foods (fresh juices, milk, liquid whey proteins and sweeteners) that are critical for UV process and systems design will follow. Available UV sources did not prove totally effective either resulting in low microbial reduction or UV over-dosing of the product thereby leading to sensory changes. Beam shaping of UV light presents new opportunities to improve dosage uniformity and delivery of UV photons in LUVT foods.

Non-photosynthetic mechanisms of growth reduction in pea (Pisum sativum L.) exposed to UV-B radiation

International Nuclear Information System (INIS)

Gonzalez, R.; Mepsted, R.; Wellburn, A.R.; Paul, N.D.

1998-01-01

Pisum sativum cv. Guido grown under controlled environment conditions was exposed to either low or high UV-B radiation (2·2 or 9·9 kJ m –2 d –1 plant-weighted UV-B, respectively). Low or high UV-B was maintained throughout growth (LL and HH treatments, respectively) or plants were transferred between treatments when 22 d old (giving LH and HL treatments). High UV-B significantly reduced plant dry weight and significantly altered plant morphology. The growth and morphology of plants transferred from low to high UV-B were little affected, when compared with those of LL plants. By contrast, plants moved from high to low UV-B showed marked increases in growth when compared with HH plants. This contrast between HL and LH appeared to be related to the effect of UV-B on plant development. Exposure to high UV-B throughout development consistently reduced leaf areas. In fully expanded leaves there was no significant UV-B effect on cell area and reduced leaf area could be attributed to reduced cell number, suggesting effects on leaf primordia. Further reductions in the leaf area of younger leaves were the result of the slower development rate of plants grown at high UV-B, which also resulted in significant reductions in leaf number. (author)

UV SEDs of early-type cluster galaxies: a new look at the UV upturn

Science.gov (United States)

Ali, S. S.; Bremer, M. N.; Phillipps, S.; De Propris, R.

2018-05-01

Using GALEX, Ultraviolet Optical Telescope (UVOT), and optical photometry, we explore the prevalence and strength of the Ultraviolet (UV) upturn in the spectra of quiescent early-type galaxies in several nearby clusters. Even for galaxies with completely passive optical colours, there is a large spread in vacuum UV colour consistent with almost all having some UV upturn component. Combining GALEX and UVOT data below 3000 Å, we generate for the first time comparatively detailed UV spectral energy distributions for Coma cluster galaxies. Fitting the UV upturn component with a blackbody, 26 of these show a range of characteristic temperatures (10 000-21 000K) for the UV upturn population. Assuming a single temperature to explain GALEX-optical colours could underestimate the fraction of galaxies with UV upturns and mis-classify some as systems with residual star formation. The UV upturn phenomenon is not an exclusive feature found only in giant galaxies; we identify galaxies with similar (or even bluer) FUV - V colours to the giants with upturns over a range of fainter luminosities. The temperature and strength of the UV upturn are correlated with galaxy mass. Under the plausible hypothesis that the sources of the UV upturn are blue horizontal branch stars, the most likely mechanism for this is the presence of a substantial (between 4 per cent and 20 per cent) Helium-rich (Y > 0.3) population of stars in these galaxies, potentially formed at z ˜ 4 and certainly at z > 2; this plausibly sets a lower limit of {˜ } {0.3- 0.8} × 10^{10} M⊙ to the in situ stellar mass of ˜L* galaxies at this redshift.

Degradation of sulfamethoxazole by UV, UV/H2O2 and UV/persulfate (PDS): Formation of oxidation products and effect of bicarbonate.

Science.gov (United States)

Yang, Yi; Lu, Xinglin; Jiang, Jin; Ma, Jun; Liu, Guanqi; Cao, Ying; Liu, Weili; Li, Juan; Pang, Suyan; Kong, Xiujuan; Luo, Congwei

2017-07-01

The frequent detection of sulfamethoxazole (SMX) in wastewater and surface waters gives rise of concerns about their ecotoxicological effects and potential risks to induce antibacterial resistant genes. UV/hydrogen peroxide (UV/H 2 O 2 ) and UV/persulfate (UV/PDS) advanced oxidation processes have been demonstrated to be effective for the elimination of SMX, but there is still a need for a deeper understanding of product formations. In this study, we identified and compared the transformation products of SMX in UV, UV/H 2 O 2 and UV/PDS processes. Because of the electrophilic nature of SO 4 - , the second-order rate constant for the reaction of sulfate radical (SO 4 - ) with the anionic form of SMX was higher than that with the neutral form, while hydroxyl radical (OH) exhibited comparable reactivity to both forms. The direct photolysis of SMX predominately occurred through cleavage of the NS bond, rearrangement of the isoxazole ring, and hydroxylation mechanisms. Hydroxylation was the dominant pathway for the reaction of OH with SMX. SO 4 - favored attack on NH 2 group of SMX to generate a nitro derivative and dimeric products. The presence of bicarbonate in UV/H 2 O 2 inhibited the formation of hydroxylated products, but promoted the formation of the nitro derivative and the dimeric products. In UV/PDS, bicarbonate increased the formation of the nitro derivative and the dimeric products, but decreased the formation of the hydroxylated dimeric products. The different effect of bicarbonate on transformation products in UV/H 2 O 2 vs. UV/PDS suggested that carbonate radical (CO 3 - ) oxidized SMX through the electron transfer mechanism similar to SO 4 - but with less oxidation capacity. Additionally, SO 4 - and CO 3 - exhibited higher reactivity to the oxazole ring than the isoxazole ring of SMX. Ecotoxicity of transformation products was estimated by ECOSAR program based on the quantitative structure-activity relationship analysis as well as by experiments using

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

Photodegradation and toxicity changes of antibiotics in UV and UV/H2O2 process

International Nuclear Information System (INIS)

Yuan Fang; Hu Chun; Hu Xuexiang; Wei Dongbin; Chen Yong; Qu Jiuhui

2011-01-01

The photodegradation of three antibiotics, oxytetracycline (OTC), doxycycline (DTC), and ciprofloxacin (CIP) in UV and UV/H 2 O 2 process was investigated with a low-pressure UV lamp system. Experiments were performed in buffered ultrapure water (UW), local surface water (SW), and treated water from local municipal drinking water treatment plant (DW) and wastewater treatment plant (WW). The efficiency of UV/H 2 O 2 process was affected by water quality. For all of the three selected antibiotics, the fastest degradation was observed in DW, and the slowest degradation occurred in WW. This phenomenon can be explained by R OH,UV , defined as the experimentally determined ·OH radical exposure per UV fluence. The R OH,UV values represent the background ·OH radical scavenging in water matrix, obtained by the degradation of para-chlorobenzoic acid (pCBA), a probe compound. In natural water, the indirect degradation of CIP did not significantly increase with the addition of H 2 O 2 due to its effective degradation by UV direct photolysis. Moreover, the formation of several photoproducts and oxidation products of antibiotics in UV/H 2 O 2 process was identified using GC-MS. Toxicity assessed by Vibrio fischer (V. fischer), was increased in UV photolysis, for the photoproducts still preserving the characteristic structure of the parent compounds. While in UV/H 2 O 2 process, toxicity increased first, and then decreased; nontoxic products were formed by the oxidation of ·OH radical. In this process, detoxification was much easier than mineralization for the tested antibiotics, and the optimal time for the degradation of pollutants in UV/H 2 O 2 process would be determined by parent compound degradation and toxicity changes.

Occurrence, distribution and ecological risk assessment of multiple classes of UV filters in surface waters from different countries.

Science.gov (United States)

Tsui, Mirabelle M P; Leung, H W; Wai, Tak-Cheung; Yamashita, Nobuyoshi; Taniyasu, Sachi; Liu, Wenhua; Lam, Paul K S; Murphy, Margaret B

2014-12-15

Organic UV filters are common ingredients of personal care products (PCPs), but little is known about their distribution in and potential impacts to the marine environment. This study reports the occurrence and risk assessment of twelve widely used organic UV filters in surface water collected in eight cities in four countries (China, the United States, Japan, and Thailand) and the North American Arctic. The number of compounds detected, Hong Kong (12), Tokyo (9), Bangkok (9), New York (8), Los Angeles (8), Arctic (6), Shantou (5) and Chaozhou (5), generally increased with population density. Median concentrations of all detectable UV filters were ethylhexyl methoxycinnamate (EHMC) were more likely to pose a risk to fishes and also posed high risk of bleaching in hard corals in aquatic recreational areas in Hong Kong. This study is the first to report the occurrence of organic UV filters in the Arctic and provides a wider assessment of their potential negative impacts in the marine environment. Copyright © 2014 Elsevier Ltd. All rights reserved.

Study on Biodegradation of Palm Oil-based UV-Curable Films in Soil

International Nuclear Information System (INIS)

Rida Tajau; Siti Farhana Fathy; Mohamad Norahiman Abdurahman; Anis Asmi Azman; Nur Amira Hamidi; Mek Zah Salleh; Nik Ghazali Nik Salleh

2014-01-01

The palm oil-based ultraviolet (UV)-curable films were subjected to an outdoor soil burial test to investigate the biodegradation under natural environment. The films were burial in the soil experiment plot at the Nuclear Malaysia's Dengkil complex which is near the BTS building at block 42. Biodegradation tests are more specific to burial film in soil experiments for 12 months under natural conditions. The biodegradability of palm oil resin based UV-curable films were investigated and compared with the petrochemical resin based film. The films properties were compared with respect to properties of the film morphology and the film weight loss which are analyzed using the scanning electron microscope (SEM), an optical microscope and the weight loss of film calculation. These findings suggested that the palm oil-based UV-curable films show quite satisfactory biodegradation levels. (author)

TEMIS UV product validation using NILU-UV ground-based measurements in Thessaloniki, Greece

Science.gov (United States)

Zempila, Melina-Maria; van Geffen, Jos H. G. M.; Taylor, Michael; Fountoulakis, Ilias; Koukouli, Maria-Elissavet; van Weele, Michiel; van der A, Ronald J.; Bais, Alkiviadis; Meleti, Charikleia; Balis, Dimitrios

2017-06-01

This study aims to cross-validate ground-based and satellite-based models of three photobiological UV effective dose products: the Commission Internationale de l'Éclairage (CIE) erythemal UV, the production of vitamin D in the skin, and DNA damage, using high-temporal-resolution surface-based measurements of solar UV spectral irradiances from a synergy of instruments and models. The satellite-based Tropospheric Emission Monitoring Internet Service (TEMIS; version 1.4) UV daily dose data products were evaluated over the period 2009 to 2014 with ground-based data from a Norsk Institutt for Luftforskning (NILU)-UV multifilter radiometer located at the northern midlatitude super-site of the Laboratory of Atmospheric Physics, Aristotle University of Thessaloniki (LAP/AUTh), in Greece. For the NILU-UV effective dose rates retrieval algorithm, a neural network (NN) was trained to learn the nonlinear functional relation between NILU-UV irradiances and collocated Brewer-based photobiological effective dose products. Then the algorithm was subjected to sensitivity analysis and validation. The correlation of the NN estimates with target outputs was high (r = 0. 988 to 0.990) and with a very low bias (0.000 to 0.011 in absolute units) proving the robustness of the NN algorithm. For further evaluation of the NILU NN-derived products, retrievals of the vitamin D and DNA-damage effective doses from a collocated Yankee Environmental Systems (YES) UVB-1 pyranometer were used. For cloud-free days, differences in the derived UV doses are better than 2 % for all UV dose products, revealing the reference quality of the ground-based UV doses at Thessaloniki from the NILU-UV NN retrievals. The TEMIS UV doses used in this study are derived from ozone measurements by the SCIAMACHY/Envisat and GOME2/MetOp-A satellite instruments, over the European domain in combination with SEVIRI/Meteosat-based diurnal cycle of the cloud cover fraction per 0. 5° × 0. 5° (lat × long) grid cells. TEMIS

TEMIS UV product validation using NILU-UV ground-based measurements in Thessaloniki, Greece

Directory of Open Access Journals (Sweden)

M.-M. Zempila

2017-06-01

Full Text Available This study aims to cross-validate ground-based and satellite-based models of three photobiological UV effective dose products: the Commission Internationale de l'Éclairage (CIE erythemal UV, the production of vitamin D in the skin, and DNA damage, using high-temporal-resolution surface-based measurements of solar UV spectral irradiances from a synergy of instruments and models. The satellite-based Tropospheric Emission Monitoring Internet Service (TEMIS; version 1.4 UV daily dose data products were evaluated over the period 2009 to 2014 with ground-based data from a Norsk Institutt for Luftforskning (NILU-UV multifilter radiometer located at the northern midlatitude super-site of the Laboratory of Atmospheric Physics, Aristotle University of Thessaloniki (LAP/AUTh, in Greece. For the NILU-UV effective dose rates retrieval algorithm, a neural network (NN was trained to learn the nonlinear functional relation between NILU-UV irradiances and collocated Brewer-based photobiological effective dose products. Then the algorithm was subjected to sensitivity analysis and validation. The correlation of the NN estimates with target outputs was high (r = 0. 988 to 0.990 and with a very low bias (0.000 to 0.011 in absolute units proving the robustness of the NN algorithm. For further evaluation of the NILU NN-derived products, retrievals of the vitamin D and DNA-damage effective doses from a collocated Yankee Environmental Systems (YES UVB-1 pyranometer were used. For cloud-free days, differences in the derived UV doses are better than 2 % for all UV dose products, revealing the reference quality of the ground-based UV doses at Thessaloniki from the NILU-UV NN retrievals. The TEMIS UV doses used in this study are derived from ozone measurements by the SCIAMACHY/Envisat and GOME2/MetOp-A satellite instruments, over the European domain in combination with SEVIRI/Meteosat-based diurnal cycle of the cloud cover fraction per 0. 5° × 0. 5�

UV-induced filamentation in bacteria of the generum Erwinia

Energy Technology Data Exchange (ETDEWEB)

Prokulevich, V A; Tomichev, Yu K

1988-09-01

It is experimentally shown that cells of 56 pectolytic Erwinia strains isolated at different tomus in different states from various natural sources are converted into filaments under UV-light effect in relatively low doses which allows one to refer them to natural Fil/sup +/ - organisms. Ability to filamentation in Erwinia bacterium correlates with secretion process to the environment of pectolytic enzymes. Bacteria of 9 E.herbicola strains investigated (without pectatlyase secretion) after irradiation do not form stretched cells. Based on the results obtained a conclusion is drawn that increased ENA49 E.chrysanthemic cell sensitivity to UV light results from its natural defect in the system, providing for cell division processes like the one revealed in E.CoLiB and Lon/sup -/ - mutants of E.Coli K-12.

MEDICAL AND ENVIRONMENTAL EFFECTS OF UV RADIATION.

Energy Technology Data Exchange (ETDEWEB)

SUTHERLAND, B.M.

2001-07-26

Organisms living on the earth are exposed to solar radiation, including its ultraviolet (UV) components (for general reviews, the reader is referred to Smith [1] and Young et al. [2]). UV wavelength regions present in sunlight are frequently designated as UVB (290-320 nm) and UVA (320-400 nm). In today's solar spectrum, UVA is the principal UV component, with UVB present at much lower levels. Ozone depletion will increase the levels of UVB reaching the biosphere, but the levels of UVA will not be changed significantly [3]. Because of the high efficiency of UVB in producing damage in biological organisms in the laboratory experiments, it has sometimes been assumed that UVA has little or no adverse biological effects. However, accumulating data [4, 5], including action spectra (efficiency of biological damage as a function of wavelength of radiation; see Section 5) for DNA damage in alfalfa seedlings [6], in human skin [7], and for a variety of plant damages (Caldwell, this volume) indicate that UVA can induce damage in DNA in higher organisms. Thus, understanding the differential effects of UVA and UVB wavebands is essential for estimating the biological consequences of stratospheric ozone depletion.

Effect of UV on DNA synthesis in UV-resistant insect cells

International Nuclear Information System (INIS)

Styer, S.C.; Meechan, P.J.; Griffiths, T.D.

1987-01-01

Insect cells are most resistant to killing by 254 nm ultraviolet light (UV) than mammalian cells. Because they have an active photolyase, it may be possible to generate a higher number of [6-4] PyC lesions per genome, allowing the possibility to distinguish between the effects of [5-6] pyrimidine lesions and the nonphotoreactable [6-4] lesions on DNA replication. IAL-PID2 cells, derived from imaginal wing discs of the Indian meal moth were exposed to UV followed by photoreactivating light (PR) or sham treatment and then analyzed by measuring the incorporation of [/sup 3/H]-thymidine into acid precipitable form. As expected, there was a fluence-dependent decrease in the amount of thymidine incorporated after exposure to UV. The response was similar to that observed in wild type CHO cells (AAS) except that the rate of decline was more rapid. When PR followed UV, there was less of a decline in thymidine incorporation and a more rapid recovery. However, thymidine incorporation did not return to control levels as rapidly as expected if [5-6] lesions were the only lesions involved in the disruption of DNA synthesis after exposure to UV

Identification and ecotoxicity of degradation products of chloroacetamide herbicides from UV-treatment of water

DEFF Research Database (Denmark)

Souissi, Yasmine; Bouchonnet, Stéphane; Bourcier, Sophie

2013-01-01

The widespread occurrence of chlorinated herbicides and their degradation products in the aquatic environment raises health and environmental concerns. As a consequence pesticides, and to a lesser degree their degradation products, are monitored by authorities both in surface waters and drinking...... waters. In this study the formation of degradation products from ultraviolet (UV) treatment of the three chloroacetamide herbicides acetochlor, alachlor and metolachlor and their biological effects were investigated. UV treatment is mainly used for disinfection in water and wastewater treatments. First...

UV Screening in Native and Non-native Plant Species in the Tropical Alpine: Implications for Climate Change-Driven Migration of Species to Higher Elevations

Directory of Open Access Journals (Sweden)

Paul W. Barnes

2017-08-01

Full Text Available Ongoing changes in Earth’s climate are shifting the elevation ranges of many plant species with non-native species often experiencing greater expansion into higher elevations than native species. These climate change-induced shifts in distributions inevitably expose plants to novel biotic and abiotic environments, including altered solar ultraviolet (UV-B (280–315 nm radiation regimes. Do the greater migration potentials of non-native species into higher elevations imply that they have more effective UV-protective mechanisms than native species? In this study, we surveyed leaf epidermal UV-A transmittance (TUV A in a diversity of plant species representing different growth forms to test whether native and non-native species growing above 2800 m elevation on Mauna Kea, Hawaii differed in their UV screening capabilities. We further compared the degree to which TUV A varied along an elevation gradient in the native shrub Vaccinium reticulatum and the introduced forb Verbascum thapsus to evaluate whether these species differed in their abilities to adjust their levels of UV screening in response to elevation changes in UV-B. For plants growing in the Mauna Kea alpine/upper subalpine, we found that adaxial TUV A, measured with a UVA-PAM fluorometer, varied significantly among species but did not differ between native (mean = 6.0%; n = 8 and non-native (mean = 5.8%; n = 11 species. When data were pooled across native and non-native taxa, we also found no significant effect of growth form on TUV A, though woody plants (shrubs and trees were represented solely by native species whereas herbaceous growth forms (grasses and forbs were dominated by non-native species. Along an elevation gradient spanning 2600–3800 m, TUV A was variable (mean range = 6.0–11.2% and strongly correlated with elevation and relative biologically effective UV-B in the exotic V. thapsus; however, TUV A was consistently low (3% and did not vary with elevation in the native

UV-induced effects

NARCIS (Netherlands)

Liebsch, M.; Spielmann, H.; Pape, W.; Krul, C.; Deguercy, A.; Eskes, C.A.M.

2005-01-01

Regulatory requirements: According to the current Notes for Guidance of the Scientific Committee on Cosmetic Products and Non-Food Products (SCCNFP), cosmetic ingredients and mixtures of ingredients absorbing UV light (in particular UV filter chemicals used, for example, to ensure the light

New technology and application in UV curing

International Nuclear Information System (INIS)

Loutz, J.M.

1999-01-01

Overview of radcure technology was presented. Its included this following subjects, radiation curable powder coatings, UV curable water based polyurethanes, photo-initiators, fire retardancy, aqueous systems, cationic, ceramic and optical grade material

Biological UV-doses and the effect on an ozone layer depletion

International Nuclear Information System (INIS)

Dahlback, A.; Henriksen, T.

1988-08-01

Effective UV-doses were calculated based on the integrated product of the biological action spectrum and the solar radiation. The calculations included absorption and scattering of UV-radiation in the atmosphere, both for normal ozone conditions as well as for a depleted ozone layer. The effective annual UV-dose increases by approximately 4% per degree of latitude towards the equator. An ozone depletion of 1% increases the annual UV-dose by approximately 1% at 60 o N. A large depletion of 50% over Scandinavia (60 o N) would give this region an effective UV-dose similar to that obtained, with normal ozone conditions, at a latitude of 40 o N (California or the Mediterranean countries). The Antarctic ozone hole increases the annual UV-dose by 20 to 25% which is a similar increase as that attained by moving 5 to 6 degrees of latitude nearer the equator. The annual UV-dose on higher latitudes is mainly determined by the summer values of ozone. Both the ozone values and the effective UV-doses vary from one year to another (within ±4%). No positive or negative trend is observed for Scandinavia from 1978 to 1988

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.

Monitoring and control of UV and UV-TiO2 disinfections for municipal wastewater reclamation using artificial neural networks

International Nuclear Information System (INIS)

Lin, Chuang-Hung; Yu, Ruey-Fang; Cheng, Wen-Po; Liu, Chun-Ru

2012-01-01

Highlights: ► ANN models can effectively control both UV and UV-TiO 2 disinfections for wastewater reuse. ► Comparing to UV disinfection, UV-TiO 2 disinfection can save 13.2–15.7% of UV dosage and capacity. ► SS decreases disinfection efficiency when UV doses were 2 . - Abstract: The use of ultraviolet (UV) irradiation as a physical wastewater disinfection has increased in recent years, especially for wastewater reuse. The UV-TiO 2 can generate OH radicals, which is highly effective to inactivate microorganisms in wastewater disinfection. However, both UV and UV-TiO 2 disinfections create multiple physical, chemical, and bio-chemical phenomena that affect their germicidal efficiency. It is difficult to build a precise control model using existing mathematic models. This study applies artificial neural network (ANN) models to control UV and UV-TiO 2 disinfections. Experimental results indicate that the ANN models, which precisely generate relationships among multiple monitored parameters, total coliform counts in influent and effluent, and UV doses, can be used as control models for UV and UV-TiO 2 disinfections. A novel ANN control strategy is applied to control UV and UV-TiO 2 disinfection processes to meet three total coliform count limits for three wastewater reuse purposes. The proposed controlled strategy effectively controls UV and UV-TiO 2 disinfection, resulting in acceptable total coliform counts in effluent for the three wastewater reuse purposes. The required UV doses for UV-TiO 2 disinfection were lower than those for UV disinfection, resulting in energy saving and capacity reduction of 13.2–15.7%.

[Occupational skin cancer : Prevention and recommendations for UV protection as part of the treatment approved by the public statutory employers' liability insurance].

Science.gov (United States)

Rocholl, M; Ludewig, M; Skudlik, C; Wilke, A

2018-04-27

In Germany, approximately 2 to 3 million employees work in outdoor professions. They are exceptionally exposed to solar ultraviolet (UV) radiation for a large part of their daily working time. Cumulative UV exposure is associated with a significantly increased risk of skin cancer for outdoor workers from various occupational groups (e. g. landscape and horticulture, agriculture and forestry, fisheries and seafaring, construction and trade, as well as sports teachers, lifeguards and mountain guides). Since 1 January 2015, squamous cell carcinoma and multiple actinic keratosis due to natural UV radiation can be recognised as occupational disease No. 5103 by the German statutory social accident insurance. Reducing cumulative UV exposure is the main prevention aspect of this type of skin damage. Therefore, technical, organisational and personal UV protection measures should be implemented in the professional and private environment. Moreover, they have to be regularly used in an appropriate way. In addition to guideline-oriented therapy, training and counselling of patients with already existing actinic skin damage or a recognised occupational disease No. 5103 is therefore of particular importance. The focus should be on improving the individual UV protection behaviour. This article gives an overview of current recommendations for UV protection in the professional environment. It outlines possible solutions for patient counselling in terms of UV protection in everyday practice.

Skin Cancer and UV Protection

Directory of Open Access Journals (Sweden)

Tarbuk Anita

2016-03-01

Full Text Available The incidence of skin cancer is increasing by epidemic proportions. Basal cell cancer remains the most common skin neoplasm, and simple excision is generally curative. On the other hand, aggressive local growth and metastasis are common features of malignant melanoma, which accounts for 75% of all deaths associated with skin cancer. The primary cause of skin cancer is long exposure to solar ultraviolet radiation (UV-R crossed with the amount of skin pigmentation and family genetics. It is believed that in childhood and adolescence, 80% of UV-R gets absorbed while in the remaining, 20 % gets absorbed later in the lifetime. This suggests that proper and early photoprotection may reduce the risk of subsequent occurrence of skin cancer. Reducing the exposure time to sunlight, using sunscreens and protective textiles are the three ways of UV protection. Most people think that all the clothing will protect them, but it does not provide full sun screening properties. Literature sources claim that only 1/3 of the spring and summer collections tested give off proper UV protection. This is very important during the summer months, when UV index is the highest. Fabric UV protection ability highly depends on large number of factors such as type of fiber, fabric surface, construction, porosity, density, moisture content, type and concentration of dyestuff, fluorescent whitening agents, UV-B protective agents (UV absorbers, as well as nanoparticles, if applied. For all of these reasons, in the present paper, the results of UV protecting ability according to AS/NZS 4399:1996 will be discussed to show that standard clothing materials are not always adequate to prevent effect of UV-R to the human skin; and to suggest the possibilities for its improvement for this purpose enhancing light conversion and scattering. Additionally, the discrepancy in UV protection was investigated in distilled water as well as Adriatic Sea water.

“An Environment Built to Include Rather than Exclude Me”: Creating Inclusive Environments for Human Well-Being

Directory of Open Access Journals (Sweden)

Natasha A. Layton

2015-09-01

Full Text Available Contemporary discourses which challenge the notion of health as the “absence of disease” are prompting changes in health policy and practice. People with disability have been influential in progressing our understanding of the impact of contextual factors in individual and population health, highlighting the impact of environmental factors on functioning and inclusion. The World Health Organization’s (WHO more holistic definition of health as “wellbeing” is now applied in frameworks and legislation, and has long been understood in occupational therapy theory. In practice, however, occupational therapists and other professionals often address only local and individual environmental factors to promote wellbeing, within systems and societies that limit equity in population health and restrict inclusion in communities. This paper presents an in-depth analysis of the supports and accommodations identified by a cohort of individuals (n-100 living with disability. A range of environmental facilitators and barriers were identified in peoples’ experience of “inclusive community environs” and found to influence inclusion and wellbeing. The roles and responsibilities of individuals, professionals, and society to enact change in environments are discussed in light of these findings. Recommendations include a focus on the subjective experience of environments, and application of theory from human rights and inclusive economics to address the multiple dimensions and levels of environments in working towards inclusion and wellbeing.

The UV-VIS optical environment of the shuttle

Science.gov (United States)

Torr, M. R.

1985-01-01

During the Spacelab 1 shuttle mission, spectroscopic measurements were made of the atmospheric emissions over a broad wavelength range extending from the extreme ultraviolet to the near infrared. Those measurements were made under a variety of vehicle attitude and sunlight conditions. Superimposed on such spectra would be any features associated with the induced vehicle environment and its interaction with solar photons and the ambient neutral atmosphere and plasma. Various anomalies and unexpected features in the spectra from the perspective of possible shuttle-induced origins are discussed. The data indicate a dramatic cleanup of the vehicle environment over the course of the 10-day mission, a strong non-atmospheric red continuum underlying the spectra at night and at large angles to the velocity vector, and a variety of molecular band distributions which are not explained by the present understanding of the atmosphere.

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

The evolutionary response of plants to increased UV-B radiation: Field studies with Arabidopsis thaliana

International Nuclear Information System (INIS)

Trumbull, V.L.; Paige, K.N.

1995-01-01

The response of a species to any environmental change is determined by both phenotypic and evolutionary adjustments. To date, the majority of research concerning the response of terrestrial plants to increased UV-B radiation has focused on phenotypic adjustments. Recently we have initiated field studies aimed at assessing genetic variation for UV-B sensitivity within a natural population of Arabidopsis thaliana. This population consists of at least eight discrete genotypes that have been confirmed by RAPD analysis. We used an incomplete block design to assess the impact of UV-B (ambient and ambient + 6 kJ) and PAR (low and high) on these genotypes. The high UV-B treatment caused a significant reduction in fruit number and plant height while the high PAR treatment caused a significant increase in these variables. In addition, there was a marginally significant (p=0.1) UV-B x PAR x maternal line interaction for fruit number, indicating that genetic variation for UV-B sensitivity within this population depends on the PAR environment. The combination of high UV-B and high PAR caused a change in fruit number (relative to the ambient UV-B/high PAR treatment) ranging from an increase of 24% to a decrease of 47%. This range was much smaller in the low PAR treatment. These results indicate the potential for increased UV-B radiation to act as an agent of natural selection within this population

High-power UV-LED degradation: Continuous and cycled working condition influence

Science.gov (United States)

Arques-Orobon, F. J.; Nuñez, N.; Vazquez, M.; Segura-Antunez, C.; González-Posadas, V.

2015-09-01

High-power (HP) UV-LEDs can replace UV lamps for real-time fluoro-sensing applications by allowing portable and autonomous systems. However, HP UV-LEDs are not a mature technology, and there are still open issues regarding their performance evolution over time. This paper presents a reliability study of 3 W UV-LEDs, with special focus on LED degradation for two working conditions: continuous and cycled (30 s ON and 30 s OFF). Accelerated life tests are developed to evaluate the influence of temperature and electrical working conditions in high-power LEDs degradation, being the predominant failure mechanism the degradation of the package. An analysis that includes dynamic thermal and optical HP UV-LED measurements has been performed. Static thermal and stress simulation analysis with the finite element method (FEM) identifies the causes of package degradation. Accelerated life test results prove that HP UV-LEDs working in cycled condition have a better performance than those working in continuous condition.

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

NDR1 modulates the UV-induced DNA-damage checkpoint and nucleotide excision repair

Energy Technology Data Exchange (ETDEWEB)

Park, Jeong-Min; Choi, Ji Ye [Department of Biological Science, Dong-A University, Busan (Korea, Republic of); Yi, Joo Mi [Research Center, Dongnam Institute of Radiological & Medical Sciences, Busan (Korea, Republic of); Chung, Jin Woong; Leem, Sun-Hee; Koh, Sang Seok [Department of Biological Science, Dong-A University, Busan (Korea, Republic of); Kang, Tae-Hong, E-mail: thkang@dau.ac.kr [Department of Biological Science, Dong-A University, Busan (Korea, Republic of)

2015-06-05

Nucleotide excision repair (NER) is the sole mechanism of UV-induced DNA lesion repair in mammals. A single round of NER requires multiple components including seven core NER factors, xeroderma pigmentosum A–G (XPA–XPG), and many auxiliary effector proteins including ATR serine/threonine kinase. The XPA protein helps to verify DNA damage and thus plays a rate-limiting role in NER. Hence, the regulation of XPA is important for the entire NER kinetic. We found that NDR1, a novel XPA-interacting protein, modulates NER by modulating the UV-induced DNA-damage checkpoint. In quiescent cells, NDR1 localized mainly in the cytoplasm. After UV irradiation, NDR1 accumulated in the nucleus. The siRNA knockdown of NDR1 delayed the repair of UV-induced cyclobutane pyrimidine dimers in both normal cells and cancer cells. It did not, however, alter the expression levels or the chromatin association levels of the core NER factors following UV irradiation. Instead, the NDR1-depleted cells displayed reduced activity of ATR for some set of its substrates including CHK1 and p53, suggesting that NDR1 modulates NER indirectly via the ATR pathway. - Highlights: • NDR1 is a novel XPA-interacting protein. • NDR1 accumulates in the nucleus in response to UV irradiation. • NDR1 modulates NER (nucleotide excision repair) by modulating the UV-induced DNA-damage checkpoint response.

Impact of Age and Insulin-Like Growth Factor-1 on DNA Damage Responses in UV-Irradiated Human Skin.

Science.gov (United States)

Kemp, Michael G; Spandau, Dan F; Travers, Jeffrey B

2017-02-26

The growing incidence of non-melanoma skin cancer (NMSC) necessitates a thorough understanding of its primary risk factors, which include exposure to ultraviolet (UV) wavelengths of sunlight and age. Whereas UV radiation (UVR) has long been known to generate photoproducts in genomic DNA that promote genetic mutations that drive skin carcinogenesis, the mechanism by which age contributes to disease pathogenesis is less understood and has not been sufficiently studied. In this review, we highlight studies that have considered age as a variable in examining DNA damage responses in UV-irradiated skin and then discuss emerging evidence that the reduced production of insulin-like growth factor-1 (IGF-1) by senescent fibroblasts in the dermis of geriatric skin creates an environment that negatively impacts how epidermal keratinocytes respond to UVR-induced DNA damage. In particular, recent data suggest that two principle components of the cellular response to DNA damage, including nucleotide excision repair and DNA damage checkpoint signaling, are both partially defective in keratinocytes with inactive IGF-1 receptors. Overcoming these tumor-promoting conditions in aged skin may therefore provide a way to lower aging-associated skin cancer risk, and thus we will consider how dermal wounding and related clinical interventions may work to rejuvenate the skin, re-activate IGF-1 signaling, and prevent the initiation of NMSC.

Impact of Age and Insulin-Like Growth Factor-1 on DNA Damage Responses in UV-Irradiated Human Skin

Directory of Open Access Journals (Sweden)

Michael G. Kemp

2017-02-01

Full Text Available The growing incidence of non-melanoma skin cancer (NMSC necessitates a thorough understanding of its primary risk factors, which include exposure to ultraviolet (UV wavelengths of sunlight and age. Whereas UV radiation (UVR has long been known to generate photoproducts in genomic DNA that promote genetic mutations that drive skin carcinogenesis, the mechanism by which age contributes to disease pathogenesis is less understood and has not been sufficiently studied. In this review, we highlight studies that have considered age as a variable in examining DNA damage responses in UV-irradiated skin and then discuss emerging evidence that the reduced production of insulin-like growth factor-1 (IGF-1 by senescent fibroblasts in the dermis of geriatric skin creates an environment that negatively impacts how epidermal keratinocytes respond to UVR-induced DNA damage. In particular, recent data suggest that two principle components of the cellular response to DNA damage, including nucleotide excision repair and DNA damage checkpoint signaling, are both partially defective in keratinocytes with inactive IGF-1 receptors. Overcoming these tumor-promoting conditions in aged skin may therefore provide a way to lower aging-associated skin cancer risk, and thus we will consider how dermal wounding and related clinical interventions may work to rejuvenate the skin, re-activate IGF-1 signaling, and prevent the initiation of NMSC.

The effects of different UV-B radiation intensities on morphological and biochemical characteristics in Ocimum basilicum L.

Science.gov (United States)

Sakalauskaitė, Jurga; Viskelis, Pranas; Dambrauskienė, Edita; Sakalauskienė, Sandra; Samuolienė, Giedrė; Brazaitytė, Aušra; Duchovskis, Pavelas; Urbonavičienė, Dalia

2013-04-01

The effects of short-term ultraviolet B (UV-B) irradiation on sweet basil (Ocimum basilicum L. cv. Cinnamon) plants at the 3-4 leaf pair and flowering stages were examined in controlled environment growth chambers. Plants were exposed to 0 (reference), 2 and 4 kJ UV-B m(-2) day(-1) over 7 days. Exposure of basil plants to supplementary UV-B light resulted in increased assimilating leaf area, fresh biomass and dry biomass. Stimulation of physiological functions in young basil plants under either applied UV-B dose resulted in increased total chlorophyll content but no marked variation in carotenoid content. At the flowering stage the chlorophyll and carotenoid contents of basil were affected by supplementary UV-B radiation, decreasing with enhanced UV-B exposure. Both total antioxidant activity (2,2-diphenyl-1-picrylhydrazyl free radical assay) and total phenolic compound content were increased by UV-B light supplementation. Young and mature basil plants differed in their ascorbic acid content, which was dependent on UV-B dose and plant age. UV-B radiation resulted in decreased nitrate content in young basil plants (3-4 leaf pair stage). These results indicate that the application of short-exposure UV-B radiation beneficially influenced both growth parameters and biochemical constituents in young and mature basil plants. © 2012 Society of Chemical Industry.

EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA); Scientific Opinion on the substantiation of a health claim related to a combination of lycopene, vitamin E, lutein and selenium and protection of the skin from UV-induced (including photo-oxidative) damage pursuant to Article 13

DEFF Research Database (Denmark)

Tetens, Inge

related to a combination of lycopene, vitamin E, lutein and selenium and protection of the skin from UV-induced (including photo-oxidative) damage. The Panel considers that the combination of lycopene, vitamin E, lutein and selenium is sufficiently characterised. The claimed effect refers to the photo...... could be drawn from this study for the scientific substantiation of the claim. The Panel concludes that a cause and effect relationship has not been established between the consumption of a combination of lycopene, vitamin E, lutein and selenium and protection of the skin from UV-induced (including......-protective activity of the food, delaying the appearance of UV-induced erythema and decreasing its intensity. The target population proposed by the applicant is healthy adults in the general population, and in particular people with sensitive skin. The Panel considers that protection of the skin from UV...

UV-LIGA technique for ECF micropumps using back UV exposure and self-alignment

Science.gov (United States)

Han, D.; Xia, Y.; Yokota, S.; Kim, J. W.

2017-12-01

This paper proposes and develops a novel UV-LIGA technique using back UV exposure and self-alignment to realize high aspect ratio micromachining (HARM) in high power density electro-conjugate fluid (ECF) micropumps. ECF is a functional fluid designed to be able to generate strong and active jet flow (ECF jetting) between anode and cathode in ECF when high DC voltage is applied. We have developed high power density ECF micropumps consisting of triangular prism and slit electrode pairs (TPSEs) fabricated by HARM. The traditional UV-LIGA technique for HARM is mainly divided into two approaches: (a) single thick layer and (b) multiple thin layers. Both methods have limitations—deformed molds in the former and misalignment between layers in the latter. Using the finite element method software COMSOL Multiphysics, we demonstrate that the deformed micro-molds critically impair the performance of ECF micropumps. In addition, we experimentally prove that the misalignment would easily trigger electric discharge in the ECF micropumps. To overcome these limitations, we conceive a new concept utilizing the seed electrode layer for electroforming as the UV shield and pattern photoresist (KMPR) by back UV exposure. The seed electrode layer should be composed of a non-transparent conductor (Au/Ti) for patterning and a transparent conductor (ITO) for wiring. Instead of ITO, we propose the concept of transparency-like electrodes comprised of thin metal line patterns. To verify this concept, KMPR layers with thicknesses of 70, 220, and 500 µm are experimentally investigated. In the case of 500 µm KMPR thickness, the concept of transparency-like electrode was partially proved. As a result, TPSEs with a height of 440 µm were successfully fabricated. Characteristic experiments demonstrated that ECF micropumps (367 mW cm-3) fabricated by back UV achieved almost the same output power density as ECF micropumps (391 mW cm-3) fabricated by front UV. This paper proves that the proposed

UV-LIGA technique for ECF micropumps using back UV exposure and self-alignment

International Nuclear Information System (INIS)

Han, D; Xia, Y; Yokota, S; Kim, J W

2017-01-01

This paper proposes and develops a novel UV-LIGA technique using back UV exposure and self-alignment to realize high aspect ratio micromachining (HARM) in high power density electro-conjugate fluid (ECF) micropumps. ECF is a functional fluid designed to be able to generate strong and active jet flow (ECF jetting) between anode and cathode in ECF when high DC voltage is applied. We have developed high power density ECF micropumps consisting of triangular prism and slit electrode pairs (TPSEs) fabricated by HARM. The traditional UV-LIGA technique for HARM is mainly divided into two approaches: (a) single thick layer and (b) multiple thin layers. Both methods have limitations—deformed molds in the former and misalignment between layers in the latter. Using the finite element method software COMSOL Multiphysics, we demonstrate that the deformed micro-molds critically impair the performance of ECF micropumps. In addition, we experimentally prove that the misalignment would easily trigger electric discharge in the ECF micropumps. To overcome these limitations, we conceive a new concept utilizing the seed electrode layer for electroforming as the UV shield and pattern photoresist (KMPR) by back UV exposure. The seed electrode layer should be composed of a non-transparent conductor (Au/Ti) for patterning and a transparent conductor (ITO) for wiring. Instead of ITO, we propose the concept of transparency-like electrodes comprised of thin metal line patterns. To verify this concept, KMPR layers with thicknesses of 70, 220, and 500 µ m are experimentally investigated. In the case of 500 µ m KMPR thickness, the concept of transparency-like electrode was partially proved. As a result, TPSEs with a height of 440 µ m were successfully fabricated. Characteristic experiments demonstrated that ECF micropumps (367 mW cm −3 ) fabricated by back UV achieved almost the same output power density as ECF micropumps (391 mW cm −3 ) fabricated by front UV. This paper proves that the

Effect of coupled UV-A and UV-C LEDs on both microbiological and chemical pollution of urban wastewaters

International Nuclear Information System (INIS)

Chevremont, A.-C.; Farnet, A.-M.; Coulomb, B.; Boudenne, J.-L.

2012-01-01

Wastewater reuse for irrigation is an interesting alternative for many Mediterranean countries suffering from water shortages. The development of new technologies for water recycling is a priority for these countries. In this study we test the efficiency of UV-LEDs (Ultraviolet-Light-Emitting Diodes) emitting UV-A or UV-C radiations, used alone or coupled, on bacterial and chemical indicators. We monitored the survival of fecal bioindicators found in urban wastewaters and the oxidation of creatinine and phenol which represent either conventional organic matter or the aromatic part of pollution respectively. It appears that coupling UV-A/UV-C i) achieves microbial reduction in wastewater more efficiently than when a UV-LED is used alone, and ii) oxidizes up to 37% of creatinine and phenol, a result comparable to that commonly obtained with photoreactants such as TiO 2 . - Highlights: ► We test UV-LEDs as an urban wastewater tertiary treatment. ► UV-A and UV-C are coupled, combining germicidal and oxidative properties of UV. ► Coupled wavelengths have the most efficient bactericidal effect. ► Coupling UV-A and UV-C leads to photooxidation of creatinine and phenol.

UV-sensitivity and repair of UV-damage in Salmonella of wild type

International Nuclear Information System (INIS)

Kondratiev, Y.S.; Brukhansky, G.V.; Andreeva, I.V.; Skavronskaya, A.G.

1977-01-01

The UV-sensitivity of wild type Salmonella strains has been compared to that of wild type E.coli and its UV-sensitive mutants. Many wild type Salmonella strains are 4-5 times more sensitive than wild type E.coli and their inactivation curve is similar to that for E.coli with a mutation in the polA gene. Alkaline sucrose gradient centrifugation has shown a deficiency of these strains in normal excision repair of UV-damaged DNA. This deficiency is not a Salmonella genus feature because one strain as resistant as wild type E.coli was found. This resistant strain showed normal excision repair in alkaline sucrose gradient centrifugation experiments. The possible influence of plasmids and mutations in repair genes on the ability of Salmonella to repair UV-damaged DNA is discussed. (orig.) [de

UV-sensitivity and repair of UV-damage in Salmonella of wild type

Energy Technology Data Exchange (ETDEWEB)

Kondratiev, Y S; Brukhansky, G V; Andreeva, I V; Skavronskaya, A G [Akademiya Meditsinskikh Nauk SSSR, Moscow. Inst. Ehpidemiologii i Mikrobiologii

1977-12-01

The UV-sensitivity of wild type Salmonella strains has been compared to that of wild type E.coli and its UV-sensitive mutants. Many wild type Salmonella strains are 4-5 times more sensitive than wild type E.coli and their inactivation curve is similar to that for E.coli with a mutation in the polA gene. Alkaline sucrose gradient centrifugation has shown a deficiency of these strains in normal excision repair of UV-damaged DNA. This deficiency is not a Salmonella genus feature because one strain as resistant as wild type E.coli was found. This resistant strain showed normal excision repair in alkaline sucrose gradient centrifugation experiments. The possible influence of plasmids and mutations in repair genes on the ability of Salmonella to repair UV-damaged DNA is discussed.

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.

Removal of Organic Dyes from Industrial Wastewaters Using UV/H2O2, UV/H2O2/Fe (II, UV/H2O2/Fe (III Processes

Directory of Open Access Journals (Sweden)

Nezamaddin Daneshvar

2007-03-01

Full Text Available UV/H2O2, UV/H2O2/Fe (II and UV/H2O2/Fe (III processes are very effective in removing pollutants from wastewater and can be used for treatment of dyestuff units wastewaters. In this study, Rhodamine B was used as a typical organic dye. Rhodamine B has found wide applications in wax, leather, and paper industries. The results from this study showed that this dye was degradable in the presence of hydrogen peroxide under UV-C irradiation (30W mercury light and Photo-Fenton process. The dye was resistant to UV irradiation. In the absence of UV irradiation, the decolorization efficiency was very negligible in the presence of hydrogen. The effects of different system variables such as initial dye concentration, duration of UV irradiation, and initial hydrogen peroxide concentration were investigated in the UV/H2O2 process. Investigation of the kinetics of the UV/H2O2 process showed that the semi-log plot of the dye concentration versus time was linear, suggesting a first order reaction. It was found that Rhodamine B decolorization efficiencies in the UV/H2O2/Fe (II and UV/H2O2/Fe (III processes were higher than that in the UV/H2O2 process. Furthermore, a solution containing 20 ppm of Rhodamine B was decolorized in the presence 18 mM of H2O2 under UV irradiation for 15 minutes. It was also found that addition of 0.1 mM Fe(II or Fe(III to the solution containing  20  ppm of the dye and 5 mM H2O2 under UV light  illumination decreased removal time to 10 min.

Single- and mixture toxicity of three organic UV-filters, ethylhexyl methoxycinnamate, octocrylene, and avobenzone on Daphnia magna.

Science.gov (United States)

Park, Chang-Beom; Jang, Jiyi; Kim, Sanghun; Kim, Young Jun

2017-03-01

In freshwater environments, aquatic organisms are generally exposed to mixtures of various chemical substances. In this study, we tested the toxicity of three organic UV-filters (ethylhexyl methoxycinnamate, octocrylene, and avobenzone) to Daphnia magna in order to evaluate the combined toxicity of these substances when in they occur in a mixture. The values of effective concentrations (ECx) for each UV-filter were calculated by concentration-response curves; concentration-combinations of three different UV-filters in a mixture were determined by the fraction of components based on EC 25 values predicted by concentration addition (CA) model. The interaction between the UV-filters were also assessed by model deviation ratio (MDR) using observed and predicted toxicity values obtained from mixture-exposure tests and CA model. The results from this study indicated that observed ECx mix (e.g., EC 10mix , EC 25mix , or EC 50mix ) values obtained from mixture-exposure tests were higher than predicted ECx mix (e.g., EC 10mix , EC 25mix , or EC 50mix ) values calculated by CA model. MDR values were also less than a factor of 1.0 in a mixtures of three different UV-filters. Based on these results, we suggest for the first time a reduction of toxic effects in the mixtures of three UV-filters, caused by antagonistic action of the components. Our findings from this study will provide important information for hazard or risk assessment of organic UV-filters, when they existed together in the aquatic environment. To better understand the mixture toxicity and the interaction of components in a mixture, further studies for various combinations of mixture components are also required. Copyright © 2016 Elsevier Inc. All rights reserved.

UV-Induced Cell Death in Plants

Science.gov (United States)

Nawkar, Ganesh M.; Maibam, Punyakishore; Park, Jung Hoon; Sahi, Vaidurya Pratap; Lee, Sang Yeol; Kang, Chang Ho

2013-01-01

Plants are photosynthetic organisms that depend on sunlight for energy. Plants respond to light through different photoreceptors and show photomorphogenic development. Apart from Photosynthetically Active Radiation (PAR; 400–700 nm), plants are exposed to UV light, which is comprised of UV-C (below 280 nm), UV-B (280–320 nm) and UV-A (320–390 nm). The atmospheric ozone layer protects UV-C radiation from reaching earth while the UVR8 protein acts as a receptor for UV-B radiation. Low levels of UV-B exposure initiate signaling through UVR8 and induce secondary metabolite genes involved in protection against UV while higher dosages are very detrimental to plants. It has also been reported that genes involved in MAPK cascade help the plant in providing tolerance against UV radiation. The important targets of UV radiation in plant cells are DNA, lipids and proteins and also vital processes such as photosynthesis. Recent studies showed that, in response to UV radiation, mitochondria and chloroplasts produce a reactive oxygen species (ROS). Arabidopsis metacaspase-8 (AtMC8) is induced in response to oxidative stress caused by ROS, which acts downstream of the radical induced cell death (AtRCD1) gene making plants vulnerable to cell death. The studies on salicylic and jasmonic acid signaling mutants revealed that SA and JA regulate the ROS level and antagonize ROS mediated cell death. Recently, molecular studies have revealed genes involved in response to UV exposure, with respect to programmed cell death (PCD). PMID:23344059

Role of ultraviolet (UV) disinfection in infection control and environmental cleaning.

Science.gov (United States)

Qureshi, Zubair; Yassin, Mohamed H

2013-06-01

Ultraviolet (UV) radiation is capable of disinfecting surfaces, water and air. The UV technology was used for many years. However, safer and more effective delivery systems of UV radiation, make it a very useful option for disinfection. Effective disinfection of environmental surfaces is a key step in the prevention of spread of infectious agents. The traditional manual cleaning is essential in assuring adequate elimination of contamination. However, terminal cleaning is frequently suboptimal or unpredictable in many circumstances. UV-C radiation is an adjunctive disinfectant new technology that could kill a wide array of microorganisms including both vegetative and spore forming pathogens. The technology is getting more affordable and has produced consistent reproducible significant reduction of bacterial contamination.

High-Sensitivity Semiconductor Photocathodes for Space-Born UV Photon-Counting and Imaging, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Many UV photon-counting and imaging applications, including space-borne astronomy, missile tracking and guidance, UV spectroscopy for chemical/biological...

Prediction of UV spectra and UV-radiation damage in actual plasma etching processes using on-wafer monitoring technique

International Nuclear Information System (INIS)

Jinnai, Butsurin; Fukuda, Seiichi; Ohtake, Hiroto; Samukawa, Seiji

2010-01-01

UV radiation during plasma processing affects the surface of materials. Nevertheless, the interaction of UV photons with surface is not clearly understood because of the difficulty in monitoring photons during plasma processing. For this purpose, we have previously proposed an on-wafer monitoring technique for UV photons. For this study, using the combination of this on-wafer monitoring technique and a neural network, we established a relationship between the data obtained from the on-wafer monitoring technique and UV spectra. Also, we obtained absolute intensities of UV radiation by calibrating arbitrary units of UV intensity with a 126 nm excimer lamp. As a result, UV spectra and their absolute intensities could be predicted with the on-wafer monitoring. Furthermore, we developed a prediction system with the on-wafer monitoring technique to simulate UV-radiation damage in dielectric films during plasma etching. UV-induced damage in SiOC films was predicted in this study. Our prediction results of damage in SiOC films shows that UV spectra and their absolute intensities are the key cause of damage in SiOC films. In addition, UV-radiation damage in SiOC films strongly depends on the geometry of the etching structure. The on-wafer monitoring technique should be useful in understanding the interaction of UV radiation with surface and in optimizing plasma processing by controlling UV radiation.

The Global Solar UV Index used in the United Kingdom

International Nuclear Information System (INIS)

New, C.; Driscoll, C.M.H.; Kitchen, K.; Miners, B.

2000-01-01

Weather forecast bulletins on television, radio and in the newspapers in the UK now include advice about the strength of the ultraviolet (UV) radiation from the sun in terms of the Global Solar UV Index. A numerical scale of 1 to 20 is used to quote the Index for anywhere in the world and the Index addresses all ethnic groups. The Index replaces the sunburn warning system. The daily UV Index is calculated by the Met. Office from documented UV radiation levels and current atmospheric data and takes into account cloud cover forecast. Armed with the knowledge of the UV Index the public will be able to assess their personal risk of sun damage at home or abroad depending on their natural skin colour. Four categories of skin colour are identified with the Index; white skin that sunburns easily, white skin that tans readily, brown skin and black skin. A colour-coded rating from low to very high is used to identify personal risk with these skin colour categories. The Global UV Index forms an important part of the 'Sun Safety Code' developed by health organisations within the UK. (author)

The Global Solar UV Index used in the United Kingdom

Energy Technology Data Exchange (ETDEWEB)

New, C.; Driscoll, C.M.H.; Kitchen, K.; Miners, B

2000-07-01

Weather forecast bulletins on television, radio and in the newspapers in the UK now include advice about the strength of the ultraviolet (UV) radiation from the sun in terms of the Global Solar UV Index. A numerical scale of 1 to 20 is used to quote the Index for anywhere in the world and the Index addresses all ethnic groups. The Index replaces the sunburn warning system. The daily UV Index is calculated by the Met. Office from documented UV radiation levels and current atmospheric data and takes into account cloud cover forecast. Armed with the knowledge of the UV Index the public will be able to assess their personal risk of sun damage at home or abroad depending on their natural skin colour. Four categories of skin colour are identified with the Index; white skin that sunburns easily, white skin that tans readily, brown skin and black skin. A colour-coded rating from low to very high is used to identify personal risk with these skin colour categories. The Global UV Index forms an important part of the 'Sun Safety Code' developed by health organisations within the UK. (author)

Role of UV light in photodamage, skin aging, and skin cancer: importance of photoprotection.

Science.gov (United States)

Gonzaga, Evelyn R

2009-01-01

Solar, and particularly UV, radiation causes molecular and cellular damage with resultant histopathologic and clinical degenerative changes, leading in turn to photosensitivity, photo-aging, and skin cancer. While our bodies have some natural UV defenses, additional protection from the sun is essential, including sun avoidance, physical protection, and sunscreen use. Sun avoidance includes limiting exposure during peak UV times (10am-4pm), avoiding UV-reflective surfaces such as sand, snow and water, and eliminating photosensitizing drugs. Physical protection includes wearing photoprotective clothing such as a broad-brimmed hat and long sleeves and use of UV-blocking films on windows. Sunscreen containing avobenzone, titanium dioxide, zinc oxide or encamsule should be used daily and frequently reapplied. To guard against the UVB spectrum, zinc oxide and titanium dioxide are particularly recommended. Sunscreen is generally under-applied at only 25% of the recommended dose, seriously compromising photoprotection. Dosage guidelines recommend using more than half a teaspoon each on head and neck area and each arm, and more than a teaspoon each on anterior torso, posterior torso, and each leg (approximately 2 mg/cm(2)).

Effect of coupled UV-A and UV-C LEDs on both microbiological and chemical pollution of urban wastewaters

Energy Technology Data Exchange (ETDEWEB)

Chevremont, A.-C., E-mail: anne-celine.chevremont@imbe.fr [Aix-Marseille Universite - CNRS, FR ECCOREV, Laboratoire Chimie de l' Environnement (FRE3416), Equipe ' Developpements Metrologiques et Chimie des Milieux' , 3 place Victor Hugo, case 29, 13331 Marseille Cedex 3 (France); Aix-Marseille Universite - CNRS, FR ECCOREV, Institut Mediterraneen de Biodiversite et d' Ecologie marine et continentale (UMR7263), Equipe ' Vulnerabilite des Systemes Microbiens' , Avenue Escadrille Normandie-Niemen, Boite 452, 13397 Marseille Cedex 20 (France); Farnet, A.-M. [Aix-Marseille Universite - CNRS, FR ECCOREV, Institut Mediterraneen de Biodiversite et d' Ecologie marine et continentale (UMR7263), Equipe ' Vulnerabilite des Systemes Microbiens' , Avenue Escadrille Normandie-Niemen, Boite 452, 13397 Marseille Cedex 20 (France); Coulomb, B.; Boudenne, J.-L. [Aix-Marseille Universite - CNRS, FR ECCOREV, Laboratoire Chimie de l' Environnement (FRE3416), Equipe ' Developpements Metrologiques et Chimie des Milieux' , 3 place Victor Hugo, case 29, 13331 Marseille Cedex 3 (France)

2012-06-01

Wastewater reuse for irrigation is an interesting alternative for many Mediterranean countries suffering from water shortages. The development of new technologies for water recycling is a priority for these countries. In this study we test the efficiency of UV-LEDs (Ultraviolet-Light-Emitting Diodes) emitting UV-A or UV-C radiations, used alone or coupled, on bacterial and chemical indicators. We monitored the survival of fecal bioindicators found in urban wastewaters and the oxidation of creatinine and phenol which represent either conventional organic matter or the aromatic part of pollution respectively. It appears that coupling UV-A/UV-C i) achieves microbial reduction in wastewater more efficiently than when a UV-LED is used alone, and ii) oxidizes up to 37% of creatinine and phenol, a result comparable to that commonly obtained with photoreactants such as TiO{sub 2}. - Highlights: Black-Right-Pointing-Pointer We test UV-LEDs as an urban wastewater tertiary treatment. Black-Right-Pointing-Pointer UV-A and UV-C are coupled, combining germicidal and oxidative properties of UV. Black-Right-Pointing-Pointer Coupled wavelengths have the most efficient bactericidal effect. Black-Right-Pointing-Pointer Coupling UV-A and UV-C leads to photooxidation of creatinine and phenol.

UV-blocking spectacle lens protects against UV-induced decline of visual performance.

Science.gov (United States)

Liou, Jyh-Cheng; Teng, Mei-Ching; Tsai, Yun-Shan; Lin, En-Chieh; Chen, Bo-Yie

2015-01-01

Excessive exposure to sunlight may be a risk factor for ocular diseases and reduced visual performance. This study was designed to examine the ability of an ultraviolet (UV)-blocking spectacle lens to prevent visual acuity decline and ocular surface disorders in a mouse model of UVB-induced photokeratitis. Mice were divided into 4 groups (10 mice per group): (1) a blank control group (no exposure to UV radiation), (2) a UVB/no lens group (mice exposed to UVB rays, but without lens protection), (3) a UVB/UV400 group (mice exposed to UVB rays and protected using the CR-39™ spectacle lens [UV400 coating]), and (4) a UVB/photochromic group (mice exposed to UVB rays and protected using the CR-39™ spectacle lens [photochromic coating]). We investigated UVB-induced changes in visual acuity and in corneal smoothness, opacity, and lissamine green staining. We also evaluated the correlation between visual acuity decline and changes to the corneal surface parameters. Tissue sections were prepared and stained immunohistochemically to evaluate the structural integrity of the cornea and conjunctiva. In blank controls, the cornea remained undamaged, whereas in UVB-exposed mice, the corneal surface was disrupted; this disruption significantly correlated with a concomitant decline in visual acuity. Both the UVB/UV400 and UVB/photochromic groups had sharper visual acuity and a healthier corneal surface than the UVB/no lens group. Eyes in both protected groups also showed better corneal and conjunctival structural integrity than unprotected eyes. Furthermore, there were fewer apoptotic cells and less polymorphonuclear leukocyte infiltration in corneas protected by the spectacle lenses. The model established herein reliably determines the protective effect of UV-blocking ophthalmic biomaterials, because the in vivo protection against UV-induced ocular damage and visual acuity decline was easily defined.

CFD modeling of a UV-A LED baffled flat-plate photoreactor for environment applications: a mining wastewater case.

Science.gov (United States)

Devia-Orjuela, John Steven; Betancourt-Buitrago, Luis Andrés; Machuca-Martinez, Fiderman

2018-06-02

The use of ultraviolet light in photoreactors for wastewater treatment has become popular as an alternative of known chemical oxidative substances. UV LED light represents cheaper, robust, and versatile alternative to traditional UV lamps. In this study, it was designed and evaluated a photoreactor with an approach of chemical fluid dynamics (CFD) and experimental validation. The evaluation consisted of (1) CFD velocity profile analysis, (2) characterization of the average light distribution with potassium ferrioxalate actinometry, (3) degradation of a typical recalcitrant metallic cyanocomplex Fe(CN) 6 3- , and (4) scavenger effect analysis in the photodegradation using potassium persulfate. Actinometrical essay concluded that the system was able to receive 1.93 μE/s. The reactor operated under turbulent regime and best result for Fe(CN) 6 3- degradation was obtained at 4 h of operation, using 5-W UV-A LEDs, with pH ~ 7 and 10 mM de S 2 O 8 2- . Baffled photoreactor demonstrated to be useful for this type of illumination and wastewater treatment.

Monitoring and control of UV and UV-TiO{sub 2} disinfections for municipal wastewater reclamation using artificial neural networks

Energy Technology Data Exchange (ETDEWEB)

Lin, Chuang-Hung [Department of Architecture, National United University, Miao-Li 360, Taiwan, ROC (China); Yu, Ruey-Fang, E-mail: rfyu@nuu.edu.tw [Department of Safety, Health and Environmental Engineering, National United University, Miao-Li 360, Taiwan, ROC (China); Cheng, Wen-Po; Liu, Chun-Ru [Department of Safety, Health and Environmental Engineering, National United University, Miao-Li 360, Taiwan, ROC (China)

2012-03-30

Highlights: Black-Right-Pointing-Pointer ANN models can effectively control both UV and UV-TiO{sub 2} disinfections for wastewater reuse. Black-Right-Pointing-Pointer Comparing to UV disinfection, UV-TiO{sub 2} disinfection can save 13.2-15.7% of UV dosage and capacity. Black-Right-Pointing-Pointer SS decreases disinfection efficiency when UV doses were <10,000 {mu}W s/cm{sup 2}. - Abstract: The use of ultraviolet (UV) irradiation as a physical wastewater disinfection has increased in recent years, especially for wastewater reuse. The UV-TiO{sub 2} can generate OH radicals, which is highly effective to inactivate microorganisms in wastewater disinfection. However, both UV and UV-TiO{sub 2} disinfections create multiple physical, chemical, and bio-chemical phenomena that affect their germicidal efficiency. It is difficult to build a precise control model using existing mathematic models. This study applies artificial neural network (ANN) models to control UV and UV-TiO{sub 2} disinfections. Experimental results indicate that the ANN models, which precisely generate relationships among multiple monitored parameters, total coliform counts in influent and effluent, and UV doses, can be used as control models for UV and UV-TiO{sub 2} disinfections. A novel ANN control strategy is applied to control UV and UV-TiO{sub 2} disinfection processes to meet three total coliform count limits for three wastewater reuse purposes. The proposed controlled strategy effectively controls UV and UV-TiO{sub 2} disinfection, resulting in acceptable total coliform counts in effluent for the three wastewater reuse purposes. The required UV doses for UV-TiO{sub 2} disinfection were lower than those for UV disinfection, resulting in energy saving and capacity reduction of 13.2-15.7%.

Effects of UV-B radiation on leaf hair traits of invasive plants-Combining historical herbarium records with novel remote sensing data.

Science.gov (United States)

Václavík, Tomáš; Beckmann, Michael; Cord, Anna F; Bindewald, Anja M

2017-01-01

levels. However, given that either non-significant or inconclusive relationships were detected within hemispheres, alternative explanations of the differences in foliar hairs are more likely, including the effects of environment, genotypes or herbivory.

Effects of UV-B radiation on leaf hair traits of invasive plants—Combining historical herbarium records with novel remote sensing data

Science.gov (United States)

Cord, Anna F.; Bindewald, Anja M.

2017-01-01

levels. However, given that either non-significant or inconclusive relationships were detected within hemispheres, alternative explanations of the differences in foliar hairs are more likely, including the effects of environment, genotypes or herbivory. PMID:28414764

Effects of UV-B radiation on leaf hair traits of invasive plants-Combining historical herbarium records with novel remote sensing data.

Directory of Open Access Journals (Sweden)

Tomáš Václavík

similar levels. However, given that either non-significant or inconclusive relationships were detected within hemispheres, alternative explanations of the differences in foliar hairs are more likely, including the effects of environment, genotypes or herbivory.

Transmission of UV-irradiance into nectarine fruit

International Nuclear Information System (INIS)

Blanke, M.M.

1996-01-01

With the global depletion of the ozone layer, leaves and fruits are increasingly exposed to UV-irradiance on the tree. Some fruits are additionally exposed postharvest to artificial germicidal W-irradiance, leading to a cumulative effect. This paper examines the transmission of UV-light (200-400 nm) by the peel of ripe nectarine fruit using UV/VIS spectrophotometry to aid understanding of UV-effects and assess the sensitivity of the peel to UV wavelengths. Yellow peel of nectarine fruit transmitted less than 0.1 % in the UV-C range of 220 to 280 nm. With longer wavelenghts, UV-light transmission increased slowly from 0.4 % at 284 nm to 1.6 % at 320 nm and, in the UV-A region, progressively from 1.9 % at 330 nm to a maximum of 13 % of incident irradiance at 400 nm. Red peel of nectarine fruit transmitted less than 0.1 % of UV-C and UV-B light, but up to 0.9 % of incident UV-A light at 400 nm. Conversely, UV-absorption of nectarine peel decreased with longer wavelengths. Hence, fruit parenchyma is more affected by UV-irradiance at wavelengths above ca. 280 nm and underneath yellow than underneath red peel

Occurrence of organic UV filters and metabolites in lebranche mullet (Mugil liza) from Brazil.

Science.gov (United States)

Molins-Delgado, Daniel; Muñoz, Ramón; Nogueira, Sylvia; Alonso, Mariana B; Torres, João Paulo; Malm, Olaf; Ziolli, Roberta Lourenço; Hauser-Davis, Rachel Ann; Eljarrat, Ethel; Barceló, Damià; Díaz-Cruz, M Silvia

2018-03-15

UV filters (UV-Fs) constitute a heterogeneous group of chemicals used as protection against the effects of UV radiation, widely used in all sort of goods and ubiquitous in the environment. The presence of these chemicals in fish is a matter of concern, because many UV-Fs display hormonal activity. In this study, muscle, gills, and liver from 11 Mugil liza individuals from the highly urbanized Guanabara Bay (Rio de Janeiro, Brazil) were analysed in order to detect eight UV-Fs and metabolites (4-dihydroxybenzophenone [BP1] (2-hydroxy-4-methoxybenzophenone [BP3], 4-methylbenzylidiene camphor [4MBC], ethylhexyl methoxycinnamate [EHMC], ethylhexyl dimethyl p-aminobenzoic acid [ODPABA], octocrylene [OC], 4-hydroxybenzophenone [4HB], and 4,4'-dihydroxybenzophenone [4DHB]) using liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Results showed that both target UV-Fs and metabolites were ubiquitous in the analysed tissues. Lower concentrations were observed in muscle and gills (3.07-31.6ngg -1 dry weight (dw)), whereas in liver significant amounts of metabolites (5.47-451ngg -1 dw) were present. With the concentrations determined in the fish, an estimation of the daily intake revealed that consumption of muscle in the diet represent from 0.3 to 15.2ng UV-Fs (kg body weight -1 ) d -1 , higher than those reported in fish for selected persistent organic pollutants (POPs). Copyright © 2017 Elsevier B.V. All rights reserved.

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)

Is ultraviolet radiation a synergistic stressor in combined exposures? The case study of Daphnia magna exposure to UV and carbendazim

International Nuclear Information System (INIS)

Ribeiro, Fabianne; Ferreira, Nuno C.G.; Ferreira, Abel; Soares, Amadeu M.V.M.; Loureiro, Susana

2011-01-01

The toxicological assessment of chemical compounds released to the environment is more accurate when mixtures of chemicals and/or interactions between chemicals and natural stressors are considered. Ultraviolet radiation can be taken as a natural stressor since the levels of UV are increasing due to the decrease of its natural filter, the stratospheric ozone concentration. Therefore, a combination of chemical exposures and increasing UV irradiance in aquatic environments is likely to occur. In the current study, combined effects of carbendazim and ultraviolet radiation were evaluated, using selected life traits as endpoints on Daphnia magna. To design combined exposures, first single chemical and natural stressor bioassays were performed: a reproduction test with carbendazim and a reproduction, feeding inhibition and Energy budget test with ultraviolet radiation. Following single exposures, the combinations of stressors included exposures to UV radiation and carbendazim for a maximum exposure time of 4 h, followed by a post-exposure period in chemically contaminated medium for a maximum of 15 days, depending on the endpoint, where the effects of the combined exposures were investigated. Statistical analyses of the data set were performed using the MixTox tool and were based on the conceptual model of Independent Action (IA) and possible deviations to synergism or antagonism, dose-ratio or dose-level response pattern. Both ultraviolet radiation and carbendazim as single stressors had negative impacts on the measured life traits of daphnids, a decrease on both feeding rates and reproduction was observed. Feeding rates and reproduction of D. magna submitted to combined exposures of ultraviolet radiation and carbendazim showed a dose-ratio deviation from the conceptual model as the best description of the data set, for both endpoints. For feeding inhibition, antagonism was observed when the UV radiation was the dominant item in combination, and for reproduction

Effect of uvs1, uvs2 and xrs mutations on the radiosensitivity and the induced mitotic recombination frequency in diploid yeast cells

International Nuclear Information System (INIS)

Suslova, N.G.; Fedorova, I.V.; Zheleznyakova, N.Yu.

1975-01-01

The influence of the loci of radiosensitivity uvs1, uvs2, and xrs in the homozygous state at the diploid level on the sensitivity to UV and ionizing radiation and induced mitotic recombination was studied in the yeast Sacch. cerevisiae. Hypersensitivity to UV irradiation was detected in the diploids uvs2 uvs2 xrs xrs in comparision with the corresponding control. The diploid uvs1 uvs1 uvs2 uvs2 does not differ in UV sensitivity from the diploid uvs1 uvs1 UVS2 UVS2. These facts demonstrate that the uvs1 and uvs2 mutations, on the one hand, and the xrs mutations, on the other, normally control different pathways of elimination of UV-induced damages. It was shown that the diploid uvs2 uvs2 xrs3 xrs3 is far more sensitive to the lethal action of x rays than the control diploid UVS2 UVS2 xrs3 xrs3. Consequently, the mutations uvs2 and xrs3 block different modes of repair of damages induced by ionizing radiation. In all the double-mutant diploids, the frequency of mitotic recombination induced by UV rays increases sharply in comparison with that of the radioresistant diploids UVS UVS XRS XRS and the UV-sensitive diploids uvs2 uvs2 XRS XRS. Possible causes of the observed phenomenon are discussed. It was established that in a diploid homozygous for the loci uvs2 xrs5, the frequency of mitotic recombination induced by x rays increases extremely sharply. This fact confirms the hypothesis that the gene product of the locus uvs2 participates in the repair of DNA after the action of ionizing radiation. (author)

[Photoionization ion mobility spectrometry (UV-IMS) for the isomeric volatile organic compounds].

Science.gov (United States)

Li, Hu; Niu, Wen-qi; Wang, Hong-mei; Huang, Chao-qun; Jiang, Hai-he; Chu, Yan-nan

2012-01-01

The construction and performance study is reported for a newly developed ultraviolet photoionization ion mobility spectrometry (UV-IMS). In the present paper, an UV-IMS technique was firstly developed to detect eleven isomeric volatile organic compounds including the differences in the structure of carbon chain, the style of function group and the position of function group. Their reduced mobility values were determined and increased in this order: linears alcohols homemade UV-IMS was around ppb-ppm.

Protective Role of Comfrey Leave Extracts on UV-induced Zebrafish Fin Damage

OpenAIRE

Cheng, Chien-Chung; Chou, Chi-Yuan; Chang, Yao-Chin; Wang, Hsuan-Wen; Wen, Chi-Chung; Chen, Yau-Hung

2014-01-01

In zebrafish, UV exposure leads to fin malformation phenotypes including fin reduction or absence. The present study evaluated UV-protective activities of comfrey leaves extracts in a zebrafish model by recording fin morphological changes. Chemopreventive effects of comfrey leave extracts were evaluated using Kaplan-Meier analysis and Cox proportional hazards regression. The results showed that (1) the mean times of return to normal fin in the UV+comfrey (50 and 100 ppm) groups were 3.43 and ...

UV-LED Curing Efficiency of Wood Coatings

Directory of Open Access Journals (Sweden)

Véronic Landry

2015-12-01

Full Text Available Ultraviolet light emitting diodes (UV-LEDs have attracted great interest in recent years. They can be used to polymerize coatings, such as those used for prefinished wood flooring. In this project, two lamps were compared for their suitability to be used on a wood flooring finishing line: a UV-microwave and a UV-LED lamp. Low heat emission was found for the UV-LED lamp compared to the UV-microwave one. This study also reveals that the 4 W/cm2 UV-LED lamp used is not powerful enough to cure UV high solids acrylate coatings while satisfactory results can be obtained for UV water-based formulations. In fact, conversion percentages were found to be low for the high solids coatings, leaving the coatings tacky. Higher conversion percentages were obtained for the UV water-based formulations. As a result, mass loss, hardness, and scratch resistance found for the samples cured by UV-LED were closed to the ones found for the samples cured using the UV microwave lamp.

Effect of far-UV and near-UV radiation on the cell surface charge of the protozoan Tritrichomonas foetus

Energy Technology Data Exchange (ETDEWEB)

Silva Filho, F C; Elias, C A; Souza, W de

1986-05-01

Cell electrophoresis was used to detect the effect of far-UV or near-UV radiation on the cell surface charge of the pathogenic protozoan Tritrichomonas foetus. Either far-UV or near-UV radiation interfered with the surface charge of T. foetus at fluences which inhibited cell growth by 50%. Both UV-radiations induced a significant decrease on surface charge of T. foetus, as evaluated by measurement of its electrophoretic mobility (EPM). Determinations of EPM of protozoa in solution of low ionic strength indicated that the decrease in the EPM induced by far-UV is much less pronounced that that observed for near-UV or control cells.

Effect of far-UV and near-UV radiation on the cell surface charge of the protozoan Tritrichomonas foetus

International Nuclear Information System (INIS)

Silva Filho, F.C.; Elias, C.A.; Souza, W. de

1986-01-01

Cell electrophoresis was used to detect the effect of far-UV or near-UV radiation on the cell surface charge of the pathogenic protozoan Tritrichomonas foetus. Either far-UV or near-UV radiation interfered with the surface charge of T. foetus at fluences which inhibited cell growth by 50%. Both UV-radiations induced a significant decrease on surface charge of T. foetus, as evaluated by measurement of its electrophoretic mobility (EPM). Determinations of EPM of protozoa in solution of low ionic strength indicated that the decrease in the EPM induced by far-UV is much less pronounced that that observed for near-UV or control cells. (author)

Impact of UV Radiation on Genome Stability and Human Health.

Science.gov (United States)

Roy, Sujit

2017-01-01

Gradual depletion of the atmospheric ozone layer during the past few years has increased the incidence of solar UV radiation specifically the UV-C on earth's surface is one of the major environmental concerns because of the harmful effects of this radiation in all forms of life. The solar UV radiation including the harmful wavelength range of UV-B (280-320 nm) represents a significant climatic stress for both animals and plants, causing damage to the fundamental biomolecules such as DNA, proteins and lipids, thus activating genotoxic stress and induces genome instability. When DNA absorbs UV-B light, energy from the photon causes covalent linkages to form between adjacent pyrimidine bases, creating photoproducts, primarily cyclobutane pyrimidine dimers (CPDs) and pyrimidine-6,4-pyrimidinone photoproduct (6,4PPs). Pyrimidine dimers create distortions in the DNA strands and therefore can inhibit DNA replication as well transcription. Lack of efficient repair of UV-induced DNA damage may induce the formation of DNA double stand breaks (DSBs), one of the serious forms of damage in DNA double helix, as well as oxidative damage. Unrepaired DSBs in the actively dividing somatic cells severely affect cell growth and development, finally results in loss of cell viability and development of various diseases, such as cancer in man.This chapter mainly highlights the incidence of solar UV-radiation on earth's surface along with the formation of major types of UV-induced DNA damage and the associated repair mechanisms as well as methods of detecting DNA damage and finally our present understanding on the impact on solar UV radiation on human health.

UV radiation and mouse models of herpes simplex virus infection

International Nuclear Information System (INIS)

Norval, Mary; El-Ghorr, A.A.

1996-01-01

Orolabial human infections with herpes simplex virus type 1 (HSV-1) are very common; following the primary epidermal infection, the virus is retained in a latent form in the trigeminal ganglia from where it can reactivate and cause a recrudescent lesion. Recrudescences are triggered by various stimuli including exposure to sunlight. In this review three categories of mouse models are used to examine the effects of UV irradiation on HSV infections: these are UV exposure prior to primary infection, UV exposure as a triggering event for recrudescence and UV exposure prior to challenge with virus is mice already immunized to HSV. In each of these models immunosuppression occurs, which is manifest, in some instances, in increased morbidity or an increased rate of recrudescence. Where known, the immunological mechanisms involved in the models are summarized and their relevance to human infections considered. (Author)

UV response on dielectric properties of nano nematic liquid crystal

Directory of Open Access Journals (Sweden)

Kamal Kumar Pandey

2018-03-01

Full Text Available In this work, we investigate the effect of UV light irradiation on the dielectric parameters of nematic liquid crystal (5CB and ZnO nanoparticles dispersed liquid crystal. With addition of nanoparticles in nematic LC are promising new materials for a variety of application in energy harvesting, displays and photonics including the liquid crystal laser. To realize many applications, however we optimize the properties of liquid crystal and understand how the UV light irradiation interact the nanoparticles and LC molecules in dispersed/doped LC. The dielectric permittivity and loss factor have discussed the pure nematic LC and dispersed/doped system after, during and before UV light exposure. The dielectric relaxation spectroscopy was carried out in the frequency range 100 Hz–10 MHz in the nematic mesophase range. Keywords: Dielectric permittivity, Relaxation frequency, Nematic liquid crystal, UV light irradiation

UV protection filters by dielectric multilayer thin films on Glass BK-7 and Infrasil 301

International Nuclear Information System (INIS)

Abdel-Aziz, M.M.; Azim, Osama A.; Abdel-Wahab, L.A.; Seddik, Mohamed M.

2006-01-01

The increasing use of Ultraviolet (UV) light in medicine, industrial environments, for cosmetic use, and even in consumer products necessitates that greater attention be paid to the potential hazards of this type of electromagnetic radiation. To avoid any adverse effects of exposure to this type of radiation, four suitable protection filters were produced to block three UV bands (UVA, UVB, and UVC). The design structure of the required dielectric multilayer filters was done by optical thin film technology using the absorbing property of UV radiation for the substrates and dielectric materials. The computer analyses of the multilayer filter formulas were prepared using Macleod Software for the production processes. The deposition technique was achieved on optical substrates (Glass BK-7 and Infrasil 301) by dielectric material combinations including Titanium dioxide (Ti 2 O 3 ), Hafnium dioxide (HfO 2 ), and Lima (mixture of oxides SiO 2 /Al 2 O 3 ); deposition being achieved using an electron beam gun. The output results of the theoretical and experimental transmittance values for spectral band from 200 nm to 800 nm were discussed in four processes. To analyze the suitability for use in 'real world' applications, the test pieces were subjected to the durability tests (adhesion, abrasion resistance, and humidity) according to Military Standard MIL-C-675C and MIL-C-48497A

UV protection filters by dielectric multilayer thin films on Glass BK-7 and Infrasil 301

Science.gov (United States)

Abdel-Aziz, M. M.; Azim, Osama A.; Abdel-Wahab, L. A.; Seddik, Mohamed M.

2006-10-01

The increasing use of Ultraviolet (UV) light in medicine, industrial environments, for cosmetic use, and even in consumer products necessitates that greater attention be paid to the potential hazards of this type of electromagnetic radiation. To avoid any adverse effects of exposure to this type of radiation, four suitable protection filters were produced to block three UV bands (UVA, UVB, and UVC). The design structure of the required dielectric multilayer filters was done by optical thin film technology using the absorbing property of UV radiation for the substrates and dielectric materials. The computer analyses of the multilayer filter formulas were prepared using Macleod Software for the production processes. The deposition technique was achieved on optical substrates (Glass BK-7 and Infrasil 301) by dielectric material combinations including Titanium dioxide (Ti 2O 3), Hafnium dioxide (HfO 2), and Lima (mixture of oxides SiO 2/Al 2O 3); deposition being achieved using an electron beam gun. The output results of the theoretical and experimental transmittance values for spectral band from 200 nm to 800 nm were discussed in four processes. To analyze the suitability for use in 'real world' applications, the test pieces were subjected to the durability tests (adhesion, abrasion resistance, and humidity) according to Military Standard MIL-C-675C and MIL-C-48497A.

Respiration shutoff in Escherichia coli after far-uv irradiation

International Nuclear Information System (INIS)

Swenson, P.A.; Norton, I.L.

1984-01-01

Damage to DNA of Escherichia coli by uv, ionizing radiation and chemicals causes a number of responses that require the recA + and lexA + gene products. The responses include error prone repair (as indicated by mutagenesis), filamentation and induction of prophage lambda. Another important rec/lex response, shutoff of respiration, which occurs 60 min after exposure to uv, is studied. Objective is to understand the genetic and biochemical bases of the shutoff process and its control

UV survival of human mycoplasmas

International Nuclear Information System (INIS)

Aoki, Shigeji; Ito, Shoko; Watanabe, Takehiko

1979-01-01

The inactivation by ultraviolet (UV) light irradiation of mycoplasma cells of five human strains was monitored by investigating the colony-forming ability. The survival curves of five strains tested indicated that the cells of Mycoplasma buccale only are single and homogenously susceptible to UV light. The effect of the repair inhibitor, caffeine, on the colony-forming ability of UV-irradiated cells was investigated with M. buccale because of its homogeneous susceptibility to UV light. The colony formation of irradiated cells was markedly depressed by post-irradiation treatment with caffeine at concentration that had little or no effect on the colony formation of unirradiated cells. The colony-forming units (CFU) of UV-irradiated cells which were kept in broth without caffeine in the dark increased without a lag as the time in the dark increased. The colony-forming ability of the irradiated cells completely recovered after 3 hr in the dark. However, when irradiated cells were kept in the presence of caffeine, no increase in their CFU was observed. The mode of action of caffeine on UV-irradiated cells closely resembles that described for other organisms which possess dark reactivation systems for UV-induced damage in deoxyribonucleic acid. Thus, the results obtained provide evidence for the existence of a dark repair function in M. buccale. (author)

Optical system for UV-laser technological equipment

Science.gov (United States)

Fedosov, Yuri V.; Romanova, Galina E.; Afanasev, Maxim Ya.

2017-09-01

Recently there has been an intensive development of intelligent industrial equipment that is highly automated and can be rapidly adjusted for certain details. This equipment can be robotics systems, automatic wrappers and markers, CNC machines and 3D printers. The work equipment considered is the system for selective curing of photopolymers using a UV-laser and UV-radiation in such equipment that leads to additional technical difficulties. In many cases for transporting the radiation from the laser to the point processed, a multi-mirror system is used: however, such systems are usually difficult to adjust. Additionally, such multi-mirror systems are usually used as a part of the equipment for laser cutting of metals using high-power IR-lasers. For the UV-lasers, using many mirrors leads to crucial radiation losses because of many reflections. Therefore, during the development of the optical system for technological equipment using UV-laser we need to solve two main problems: to transfer the radiation for the working point with minimum losses and to include the system for controlling/handling the radiation spot position. We introduce a system for working with UV-lasers with 450mW of power and a wavelength of 0.45 μm based on a fiber system. In our modelling and design, we achieve spot sizes of about 300 μm, and the designed optical and mechanical systems (prototypes) were manufactured and assembled. In this paper, we present the layout of the technological unit, the results of the theoretical modelling of some parts of the system and some experimental results.

Immune response to UV-induced tumors: mediation of progressor tumor rejection by natural killer cells

International Nuclear Information System (INIS)

Streeter, P.R.; Fortner, G.W.

1986-01-01

Skin tumors induced in mice by chronic ultraviolet (UV) irradiation are highly antigenic and can induce a state of transplantation immunity in syngeneic animals. In the present study, the authors compared the in vitro cytolytic activity of splenic lymphocytes from mice immunized with either regressor or progressor UV-tumors. The results of this comparison implicated tumor-specific cytolytic T (Tc) lymphocytes in rejection of regressor UV-tumors, and revealed that immunization with the progressor UV-tumor 2237 failed to elicit detectable levels of progressor tumor-specific Tc cells even as the tumors rejected. Following in vitro resensitization of spleen cells from either regressor or progressor tumor immune animals, the authors found NK-like lymphocytes with anti-tumor activity. As the authors had not detected cells with this activity in splenic lymphocyte preparations prior to in vitro resensitization, the authors examined lymphocytes from the local tumor environment during the course of progressor tumor rejection for this activity. This analysis revealed NK lymphocytes exhibiting significant levels of cytolytic activity against UV-tumors. These results implicate NK cells as potential effector cells in the rejection of progressor UV-tumors by immune animals, and suggests that these cells may be regulated by T lymphocytes

Polycyclic aromatic hydrocarbons (PAHs) skin permeation rates change with simultaneous exposures to solar ultraviolet radiation (UV-S).

Science.gov (United States)

Hopf, Nancy B; Spring, Philipp; Hirt-Burri, Nathalie; Jimenez, Silvia; Sutter, Benjamin; Vernez, David; Berthet, Aurelie

2018-05-01

Road construction workers are simultaneously exposed to two carcinogens; solar ultraviolet (UV-S) radiation and polycyclic aromatic hydrocarbons (PAHs) in bitumen emissions. The combined exposure may lead to photogenotoxicity and enhanced PAH skin permeation rates. Skin permeation rates (J) for selected PAHs in a mixture (PAH-mix) or in bitumen fume condensate (BFC) with and without UV-S co-exposures were measured with in vitro flow-through diffusion cells mounted with human viable skin and results compared. Possible biomarkers were explored. Js were greater with UV-S for naphthalene, anthracene, and pyrene in BFC (0.08-0.1 ng/cm 2 /h) compared to without (0.02-0.26 ng/cm 2 /h). This was true for anthracene, pyrene, and chrysene in the PAH-mix. Naphthalene and benzo(a)pyrene (BaP) in the PAH-mix had greater Js without (0.97-13.01 ng/cm 2 /h) compared to with UV-S (0.40-6.35 ng/cm 2 /h). Time until permeation (T lags ) in the PAH-mix were generally shorter compared to the BFC, and they ranged from 1 to 13 h. The vehicle matrix could potentially be the reason for this discrepancy as BFC contains additional not identified substances. Qualitative interpretation of p53 suggested a dose-response with UV-S, and somewhat with the co-exposures. MMP1, p65 and cKIT were not exploitable. Although not statistically different, PAHs permeate human viable skin faster with simultaneous exposures to UV. Copyright © 2018 Elsevier B.V. All rights reserved.

Integrated model of port oil piping transportation system safety including operating environment threats

Directory of Open Access Journals (Sweden)

Kołowrocki Krzysztof

2017-06-01

Full Text Available The paper presents an integrated general model of complex technical system, linking its multistate safety model and the model of its operation process including operating environment threats and considering variable at different operation states its safety structures and its components safety parameters. Under the assumption that the system has exponential safety function, the safety characteristics of the port oil piping transportation system are determined.

Integrated model of port oil piping transportation system safety including operating environment threats

OpenAIRE

Kołowrocki, Krzysztof; Kuligowska, Ewa; Soszyńska-Budny, Joanna

2017-01-01

The paper presents an integrated general model of complex technical system, linking its multistate safety model and the model of its operation process including operating environment threats and considering variable at different operation states its safety structures and its components safety parameters. Under the assumption that the system has exponential safety function, the safety characteristics of the port oil piping transportation system are determined.

The history of the UV radiation climate of the earth--theoretical and space-based observations.

Science.gov (United States)

Cockell, C S; Horneck, G

2001-04-01

In the Archean era (3.8-2.5 Ga ago) the Earth probably lacked a protective ozone column. Using data obtained in the Earth's orbit on the inactivation of Bacillus subtilis spores we quantitatively estimate the potential biological effects of such an environment. We combine this practical data with theoretical calculations to propose a history of the potential UV stress on the surface of the Earth over time. The data suggest that an effective ozone column was established at a pO2 of approximately 5 x 10(-3) present atmospheric level. The improvement in the UV environment on the early Proterozoic Earth might have been a much more rapid event than has previously been supposed, with DNA damage rates dropping by two orders of magnitude in the space of just a few tens of millions of years. We postulate that a coupling between reduced UV stress and increased pO2 production could have contributed toward a positive feedback in the production of ozone in the early Proterozoic atmosphere. This would contribute to the apparent rapidity of the oxidation event. The data provide an evolutionary perspective on present-day Antarctic ozone depletion.

Ultraviolet radiation exposure from UV-transilluminators.

Science.gov (United States)

Akbar-Khanzadeh, Farhang; Jahangir-Blourchian, Mahdi

2005-10-01

UV-transilluminators use ultraviolet radiation (UVR) to visualize proteins, DNA, RNA, and their precursors in a gel electrophoresis procedure. This study was initiated to evaluate workers' exposure to UVR during their use of UV-transilluminators. The levels of irradiance of UV-A, UV-B, and UV-C were determined for 29 UV-transilluminators at arbitrary measuring locations of 6, 25, 62, and 125 cm from the center of the UV-transilluminator's filter surface in the direction of the operator's head. The operators (faculty, research staff, and graduate students) worked within 62 cm of the transilluminators, with most subjects commonly working at time ranged from 1 to 60 min. Actinic hazard (effective irradiance level of UVR) was also determined for three representative UV-transilluminators at arbitrary measuring locations of 2.5, 5, 10, 15, 20, 30, 40, and 50 cm from these sets' filter surface in the direction of the operator's head. The allowable exposure time for these instruments was less than 20 sec within 15 cm, less than 35 sec within 25 cm, and less than 2 min within 50 cm from the UV-transilluminators' filter surface. The results of this study suggest that the use of UV-transilluminators exposes operators to levels of UVR in excess of exposure guidelines. It is recommended that special safety training be provided for the affected employees and that exposure should be controlled by one or the combination of automation, substitution, isolation, posted warning signs, shielding, and/or personal protective equipment.

Photodegradation and toxicity changes of antibiotics in UV and UV/H{sub 2}O{sub 2} process

Energy Technology Data Exchange (ETDEWEB)

Fang, Yuan [State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085 (China); Hu Chun, E-mail: huchun@rcees.ac.cn [State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085 (China); Xuexiang, Hu; Dongbin, Wei; Yong, Chen; Jiuhui, Qu [State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085 (China)

2011-01-30

The photodegradation of three antibiotics, oxytetracycline (OTC), doxycycline (DTC), and ciprofloxacin (CIP) in UV and UV/H{sub 2}O{sub 2} process was investigated with a low-pressure UV lamp system. Experiments were performed in buffered ultrapure water (UW), local surface water (SW), and treated water from local municipal drinking water treatment plant (DW) and wastewater treatment plant (WW). The efficiency of UV/H{sub 2}O{sub 2} process was affected by water quality. For all of the three selected antibiotics, the fastest degradation was observed in DW, and the slowest degradation occurred in WW. This phenomenon can be explained by R{sub OH,UV}, defined as the experimentally determined {center_dot}OH radical exposure per UV fluence. The R{sub OH,UV} values represent the background {center_dot}OH radical scavenging in water matrix, obtained by the degradation of para-chlorobenzoic acid (pCBA), a probe compound. In natural water, the indirect degradation of CIP did not significantly increase with the addition of H{sub 2}O{sub 2} due to its effective degradation by UV direct photolysis. Moreover, the formation of several photoproducts and oxidation products of antibiotics in UV/H{sub 2}O{sub 2} process was identified using GC-MS. Toxicity assessed by Vibrio fischer (V. fischer), was increased in UV photolysis, for the photoproducts still preserving the characteristic structure of the parent compounds. While in UV/H{sub 2}O{sub 2} process, toxicity increased first, and then decreased; nontoxic products were formed by the oxidation of {center_dot}OH radical. In this process, detoxification was much easier than mineralization for the tested antibiotics, and the optimal time for the degradation of pollutants in UV/H{sub 2}O{sub 2} process would be determined by parent compound degradation and toxicity changes.

Photodegradation of sulfasalazine and its human metabolites in water by UV and UV/peroxydisulfate processes.

Science.gov (United States)

Ji, Yuefei; Yang, Yan; Zhou, Lei; Wang, Lu; Lu, Junhe; Ferronato, Corinne; Chovelon, Jean-Marc

2018-04-15

The widespread occurrence of pharmaceuticals and their metabolites in natural waters has raised great concerns about their potential risks on human health and ecological systems. This study systematically investigates the degradation of sulfasalazine (SSZ) and its two human metabolites, sulfapyridine (SPD) and 5-aminosalicylic acid (5-ASA), by UV and UV/peroxydisulfate (UV/PDS) processes. Experimental results show that SPD and 5-ASA were readily degraded upon UV 254 nm direct photolysis, with quantum yields measured to be (8.6 ± 0.8) × 10 -3 and (2.4 ± 0.1) × 10 -2  mol Einstein -1 , respectively. Although SSZ was resistant to direct UV photolysis, it could be effectively removed by both UV/H 2 O 2 and UV/PDS processes, with fluence-based pseudo-first-order rate constants determined to be 0.0030 and 0.0038 cm 2  mJ -1 , respectively. Second-order rate constant between SO 4 •- and SSZ was measured as (1.33 ± 0.01) × 10 9  M -1 s -1 by competition kinetic method. A kinetic model was established for predicting the degradation rate of SSZ in the UV/PDS process. Increasing the dosage of PDS significantly enhanced the degradation of SSZ in the UV/PDS process, which can be well predicted by the developed kinetic model. Natural water constituents, such as natural organic matter (NOM) and bicarbonate (HCO 3 - ), influenced the degradation of SSZ differently. The azo functional group of SSZ molecule was predicted as the reactive site susceptible to electrophilic attack by SO 4 •- by frontier electron densities (FEDs) calculations. Four intermediate products arising from azo bond cleavage and SO 2 extrusion were identified by solid phase extraction-liquid chromatography-triple quadrupole mass spectrometry (SPE-LC-MS/MS). Based on the products identified, detailed transformation pathways for SSZ degradation in the UV/PDS system were proposed. Results reveal that UV/PDS could be an efficient approach for remediation of water

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

Cerium oxide nanoparticles, combining antioxidant and UV shielding properties, prevent UV-induced cell damage and mutagenesis

Science.gov (United States)

Caputo, Fanny; de Nicola, Milena; Sienkiewicz, Andrzej; Giovanetti, Anna; Bejarano, Ignacio; Licoccia, Silvia; Traversa, Enrico; Ghibelli, Lina

2015-09-01

Efficient inorganic UV shields, mostly based on refracting TiO2 particles, have dramatically changed the sun exposure habits. Unfortunately, health concerns have emerged from the pro-oxidant photocatalytic effect of UV-irradiated TiO2, which mediates toxic effects on cells. Therefore, improvements in cosmetic solar shield technology are a strong priority. CeO2 nanoparticles are not only UV refractors but also potent biological antioxidants due to the surface 3+/4+ valency switch, which confers anti-inflammatory, anti-ageing and therapeutic properties. Herein, UV irradiation protocols were set up, allowing selective study of the extra-shielding effects of CeO2vs. TiO2 nanoparticles on reporter cells. TiO2 irradiated with UV (especially UVA) exerted strong photocatalytic effects, superimposing their pro-oxidant, cell-damaging and mutagenic action when induced by UV, thereby worsening the UV toxicity. On the contrary, irradiated CeO2 nanoparticles, via their Ce3+/Ce4+ redox couple, exerted impressive protection on UV-treated cells, by buffering oxidation, preserving viability and proliferation, reducing DNA damage and accelerating repair; strikingly, they almost eliminated mutagenesis, thus acting as an important tool to prevent skin cancer. Interestingly, CeO2 nanoparticles also protect cells from the damage induced by irradiated TiO2, suggesting that these two particles may also complement their effects in solar lotions. CeO2 nanoparticles, which intrinsically couple UV shielding with biological and genetic protection, appear to be ideal candidates for next-generation sun shields.

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.)

Conformation of L-Tyrosine Studied by Fluorescence-Detected UV-UV and IR-UV Double-Resonance Spectroscopy

OpenAIRE

Inokuchi, Yoshiya; Kobayashi, Yusuke; Ito, Takafumi; Ebata, Takayuki

2007-01-01

The laser-induced fluorescence spectrum of jet-cooled L-tyrosine exhibits more than 20 vibronic bands in the 35450-35750 cm-1 region. We attribute these bands to eight conformers by using results of UV-UV hole-burning spectroscopy. These isomers are classified into four groups; each group consists of two rotational isomers that have a similar side-chain conformation but different orientations of the phenolic OH. The splitting of band origins of rotational isomers is 31, 21, 5, and 0 cm-1 for ...

Inactivation kinetics and efficiencies of UV-LEDs against Pseudomonas aeruginosa, Legionella pneumophila, and surrogate microorganisms.

Science.gov (United States)

Rattanakul, Surapong; Oguma, Kumiko

2018-03-01

To demonstrate the effectiveness of UV light-emitting diodes (UV-LEDs) to disinfect water, UV-LEDs at peak emission wavelengths of 265, 280, and 300 nm were adopted to inactivate pathogenic species, including Pseudomonas aeruginosa and Legionella pneumophila, and surrogate species, including Escherichia coli, Bacillus subtilis spores, and bacteriophage Qβ in water, compared to conventional low-pressure UV lamp emitting at 254 nm. The inactivation profiles of each species showed either a linear or sigmoidal survival curve, which both fit well with the Geeraerd's model. Based on the inactivation rate constant, the 265-nm UV-LED showed most effective fluence, except for with E. coli which showed similar inactivation rates at 265 and 254 nm. Electrical energy consumption required for 3-log 10 inactivation (E E,3 ) was lowest for the 280-nm UV-LED for all microbial species tested. Taken together, the findings of this study determined the inactivation profiles and kinetics of both pathogenic bacteria and surrogate species under UV-LED exposure at different wavelengths. We also demonstrated that not only inactivation rate constants, but also energy efficiency should be considered when selecting an emission wavelength for UV-LEDs. Copyright © 2017 Elsevier Ltd. All rights reserved.

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.

In vivo measurements of daily UV exposure of human anterior teeth using CaF{sub 2}:Tb,Sm as a thermoluminescence dosimeter

Energy Technology Data Exchange (ETDEWEB)

Saito, W., E-mail: saito-wataru@tsurumi-u.ac.j [Department of Operative Dentistry, Tsurumi University, School of Dental Medicine, 2-1-3, Tsurumi, Tsurumi-ku, Yokohama (Japan); Ikejima, I. [Department of Operative Dentistry, Tsurumi University, School of Dental Medicine, 2-1-3, Tsurumi, Tsurumi-ku, Yokohama (Japan); Fukuda, Y. [Department of Urban Environment, Faculty of Human Environment, Osaka Sangyo University, 3-1-1, Nakagaito, Daito, Osaka (Japan); Momoi, Y. [Department of Operative Dentistry, Tsurumi University, School of Dental Medicine, 2-1-3, Tsurumi, Tsurumi-ku, Yokohama (Japan)

2011-03-15

Ultraviolet radiation (UV) has been indicated as one of the causes of discoloration of dental materials yet the standard requires that dental polymers be irradiated with light from a xenon lamp, which includes UV, to evaluate their color stability. It is doubtful that dental polymers in the mouth are exposed to large energy of UV on a daily basis, but there have been no reports concerning exposure. In the present study, we used thermoluminescence (TL) from sintered CaF{sub 2}:Tb,Sm, which is highly sensitive to UV, to measure the daily energy of UV exposure to the labial surface of the maxillary anterior teeth, which are regarded as receiving the maximum exposure among oral tissues. We produced disks of CaF{sub 2} co-doped with Tb{sub 4}O{sub 7} and Sm{sub 2}O{sub 3} (sintered CaF{sub 2}:Tb,Sm) that were 5 mm in diameter and 1 mm thick, and placed them inside glass cases that had a 7-mm external diameter, 3-mm height, and 1-mm thickness of glass made of synthetic silica with {>=}90% UV transmittance. These glass cases were fixed in dental mouthpieces in a position corresponding to the central maxillary incisors. These mouthpieces were worn by 11 subjects and UV measurements were carried out over a 24-h period in a uniform environment. The results of these TL measurements showed a TL glow peak in the region of 430 K. This was the same as that seen with irradiation from a xenon lamp as basic illumination. The daily UV radiant energy was 72.2 mJ/cm{sup 2} (32.7-143.8 mJ/cm{sup 2}), calculated from the relationship between TL intensity and UV radiant energy. This corresponded to 0.02% of the UV radiant energy contained in the light irradiation specified by ISO 4049.

Efficiency of ocular UV protection by clear lenses.

Science.gov (United States)

Rifai, Katharina; Hornauer, Matthias; Buechinger, Ramona; Schoen, Roland; Barraza-Bernal, Maria; Habtegiorgis, Selam; Glasenapp, Carsten; Wahl, Siegfried; Mappes, Timo

2018-04-01

Ocular UV doses accumulate all-day, not only during periods of direct sun exposure. The UV protection efficiency of three clear lenses was evaluated experimentally, validated by simulation, and compared to non-UV protection: a first spectacle lens with a tailored UV absorber, a second spectacle lens, minimizing UV back reflections, as well as a third spectacle lens, combining both. A tailored UV-absorber efficiently reduced overall UV irradiance to 7 %, whereas reduction of back-reflections still left UV irradiance at 42 %. Thus, clear lenses with a tailored UV absorber efficiently protect the eye from UV, supplementing sun glasses wear to an all-day protection scenario.

Lifestyle, sun worshipping and sun tanning - what about UV-A sun beds?

International Nuclear Information System (INIS)

Thune, P.

1991-01-01

This article considers the effects of ultraviolet (UV) light from the sun and UV-A sun beds on the skin. Sun worshipping and sun therapy has been en vogue for centuries, but in another way than used today. A changing lifestyle has led to an increase of various skin diseases, including skin cancer. Short wave UV-light (UV-B) in particular has been blamed for inducing not only erythema and pigmentation but also more chronic skin lesions. Long wave UV-light (UV-A) has been shown to be the cause of similar changes to the skin but the pigmentation is of another quality and affords less protection against the harmful effects of UV-B. A concept of sun reactive skin typing has been created. This is based on self-reported responses to an initial exposure to sun as regards tanning ability and erythema reaction. These two factors have certain practical consequences, not only for UV-phototherapy but also for a person's risk of developing skin cancer. Recently, several research groups and dermatologists have discouraged extensive use of UV-A sun beds because of side effects of varying degrees of seriousness. The possible implications of these side effects for the organism are not fully elucidated and may be more profound than known today. The British Photodermatology Group has issued more stringent rules for persons who, despite advice to the contrary, still wish to use UV-A sun beds. 14 refs., 1 tab

Exposure to solar UV in Finland

Energy Technology Data Exchange (ETDEWEB)

Jokela, K; Leszczynski, K; Visuri, R; Ylianttila, L [Finnish Centre for Radiation and Nuclear Safety, Helsinki (Finland)

1996-12-31

Exceptionally low total ozone, up to 40 % below the normal level, was measured over Northern Europe during winter and spring in 1992 and 1993. In 1993 the depletion persisted up to the end of May, resulting in a significant increase in biologically effective ultraviolet (UV) radiation. The increases were significantly smaller in 1992 and 1994 than in 1993. A special interest in Northern Europe is the effect of high reflection of UV from the snow. The period from the mid March to the mid May is critical in Northern Finland, because in that time the UV radiation is intense enough to cause significant biological effects, and the UV enhancing snow still covers the ground. Moreover, there is some evidence of increasing springtime depletions of ozone over Arctic regions. In this study the increase of UV exposure associated with the ozone depletions was examined with measurements and theoretical calculations. The measurements were carried out with spectroradiometrically calibrated Solar Light Model 500 and 501 UV radiometers which measure the erythemally effective UV doses and dose rates. The theoretical UV doses and dose rates were computed with the clear sky model of Green

Exposure to solar UV in Finland

Energy Technology Data Exchange (ETDEWEB)

Jokela, K.; Leszczynski, K.; Visuri, R.; Ylianttila, L. [Finnish Centre for Radiation and Nuclear Safety, Helsinki (Finland)

1995-12-31

Exceptionally low total ozone, up to 40 % below the normal level, was measured over Northern Europe during winter and spring in 1992 and 1993. In 1993 the depletion persisted up to the end of May, resulting in a significant increase in biologically effective ultraviolet (UV) radiation. The increases were significantly smaller in 1992 and 1994 than in 1993. A special interest in Northern Europe is the effect of high reflection of UV from the snow. The period from the mid March to the mid May is critical in Northern Finland, because in that time the UV radiation is intense enough to cause significant biological effects, and the UV enhancing snow still covers the ground. Moreover, there is some evidence of increasing springtime depletions of ozone over Arctic regions. In this study the increase of UV exposure associated with the ozone depletions was examined with measurements and theoretical calculations. The measurements were carried out with spectroradiometrically calibrated Solar Light Model 500 and 501 UV radiometers which measure the erythemally effective UV doses and dose rates. The theoretical UV doses and dose rates were computed with the clear sky model of Green

Serious complications in experiments in which UV doses are effected by using different lamp heights.

Science.gov (United States)

Flint, Stephan D; Ryel, Ronald J; Hudelson, Timothy J; Caldwell, Martyn M

2009-10-06

Many experiments examining plant responses to enhanced ultraviolet-B radiation (280-315nm) simply compare an enhanced UV-B treatment with ambient UV-B (or no UV-B radiation in most greenhouse and controlled-environment studies). Some more detailed experiments utilize multiple levels of UV-B radiation. A number of different techniques have been used to adjust the UV dose. One common technique is to place racks of fluorescent UV-emitting lamps at different heights above the plant canopy. However, the lamps and associated support structure cast shadows on the plant bed below. We calculated one example of the sequence of shade intervals for two common heights of lamp racks and show the patterns and duration of shade which the plants receive is distributed differently over the course of the day for different heights of the lamp racks. We also conducted a greenhouse experiment with plants (canola, sunflower and maize) grown under unenergized lamp racks suspended at the same two heights above the canopy. Growth characteristics differed in unpredictable ways between plants grown under the two heights of lamp racks. These differences could enhance or obscure potential UV-B effects. Also, differences in leaf mass per unit foliage area, which were observed in this experiment, could contribute to differences in plant UV-B sensitivity. We recommend the use of other techniques for achieving multiple doses of UV-B radiation. These range from simple and inexpensive approaches (e.g., wrapping individual fluorescent tubes in layers of a neutral-density filter such as cheese cloth) to more technical and expensive alternatives (e.g., electronically modulated lamp control systems). These choices should be determined according to the goals of the particular experiment.

The fascinating diatom frustule—can it play a role for attenuation of UV radiation?

DEFF Research Database (Denmark)

Ellegaard, Marianne; Lenau, Torben Anker; Lundholm, Nina

2016-01-01

size range as wave lengths of visible and ultraviolet (UV) light. This has prompted research into the possible role of the frustule in mediating light for the diatoms’ photosynthesis as well as into possible photonic applications of the diatom frustule. One of the possible biological roles, as well...... as area of potential application, is UV protection. In this review, we explore the possible adaptive value of the silica frustule with focus on research on the effect of UV radiation ondiatoms. We also explore the possible effect of the frustules on UV radiation, from a theoretical, biological......, and applied perspective, including recent experimental data on UV transmission of diatom frustules....

UV inactivation: Combined effects of UV radiation and xenobiotics in two strains of Saccharomyces

International Nuclear Information System (INIS)

Lochmann, E.R.; Lochmann, G.

1997-01-01

The effects of eight chemicals on the inactivation rate of ultraviolet radiation on the colony building capabilities of two strains of Saccharomyces cervisae - a wild type strain and a mutant deficient in excision repair - were studied. The insecticide methoxychlor, the herbicide 2,4-dichlorophenoxyacetic acid, the fungicide pentachlorophenol and its metabolite tetrachlorohydroquinone, as well as the chemicals acrylonitrile and 2,3-dichloro-1-propene have no significant impact on the effects of UV radiation in Saccharomyces cerevisae. Depending on the concentration, trichloroethylene increases the sensitivity to UV radiation. The herbicide paraquat provides efficient protection against UV radiation at concentrations where a toxic effect cannot be observed even without UV. The results were rather similar for both strains. (orig.) [de

UV DISINFECTION GUIDANCE MANUAL FOR THE ...

Science.gov (United States)

Provides technical information on selection, design and operation of UV systems; provides regulatory agencies with guidance and the necessary tools to assess UV systems at the design, start-up, and routine operation phase; provides manufacturers with the testing and performance standards for UV components and systems for treating drinking water. Provide guidance to water systems, regulators and manufacturers on UV disinfection of drinking water.

Is UV-A radiation a cause of malignant melanoma. Er UV-A aarsak til malignt melanom

Energy Technology Data Exchange (ETDEWEB)

Moan, J. (Det Norske Radiumhospital, Oslo (Norway))

1994-03-01

The first action spectrum for cutaneous malignant melanoma was published recently. This spectrum was obtained using the fish Xiphophorus. If the same action spectrum applies to humans, the following statements are true: Sunbathing products (agents to protect against the sun) that absorb UV-B radiation provide almost no protection against cutaneous malignant melanoma. UV-A-solaria are more dangerous than expected so far. If people are determined to use artificial sources of radiation for tanning, they should choose UV-B solaria rather than UV-A-solaria. Fluorescent tubes and halogen lamps may have weak melanomagenic effects. Ozone depletion has almost no effect on the incidence rates of CMM, since ozone absorbs very little UV-A radiation. Sunbathing products which contain UV-A-absorbing compounds or neutral filter (like titanium oxide) provide real protection against cutaneous malignant melanoma, at least if they are photochemically inert. 34 refs., 2 figs.

HAZMAT. I. The evolution of far-UV and near-UV emission from early M stars

International Nuclear Information System (INIS)

Shkolnik, Evgenya L.; Barman, Travis S.

2014-01-01

The spectral energy distribution, variability, and evolution of the high-energy radiation from an M dwarf planet host is crucial in understanding the planet's atmospheric evolution and habitability and in interpreting the planet's spectrum. The star's extreme-UV (EUV), far-UV (FUV), and near-UV (NUV) emission can chemically modify, ionize, and erode the atmosphere over time. This makes determining the lifetime exposure of such planets to stellar UV radiation critical for both the evolution of a planet's atmosphere and our potential to characterize it. Using the early M star members of nearby young moving groups, which sample critical ages in planet formation and evolution, we measure the evolution of the GALEX NUV and FUV flux as a function of age. The median UV flux remains at a 'saturated' level for a few hundred million years, analogous to that observed for X-ray emission. By the age of the Hyades Cluster (650 Myr), we measure a drop in UV flux by a factor of 2-3 followed by a steep drop from old (several Gyrs) field stars. This decline in activity beyond 300 Myr follows roughly t –1 . Despite this clear evolution, there remains a wide range, of 1-2 orders of magnitude, in observed emission levels at every age. These UV data supply the much-needed constraints to M dwarf upper-atmosphere models, which will provide empirically motivated EUV predictions and more accurate age-dependent UV spectra as inputs to planetary photochemical models.

HAZMAT. I. The evolution of far-UV and near-UV emission from early M stars

Energy Technology Data Exchange (ETDEWEB)

Shkolnik, Evgenya L. [Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States); Barman, Travis S., E-mail: shkolnik@lowell.edu, E-mail: barman@lpl.arizona.edu [Department of Planetary Sciences and Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States)

2014-10-01

The spectral energy distribution, variability, and evolution of the high-energy radiation from an M dwarf planet host is crucial in understanding the planet's atmospheric evolution and habitability and in interpreting the planet's spectrum. The star's extreme-UV (EUV), far-UV (FUV), and near-UV (NUV) emission can chemically modify, ionize, and erode the atmosphere over time. This makes determining the lifetime exposure of such planets to stellar UV radiation critical for both the evolution of a planet's atmosphere and our potential to characterize it. Using the early M star members of nearby young moving groups, which sample critical ages in planet formation and evolution, we measure the evolution of the GALEX NUV and FUV flux as a function of age. The median UV flux remains at a 'saturated' level for a few hundred million years, analogous to that observed for X-ray emission. By the age of the Hyades Cluster (650 Myr), we measure a drop in UV flux by a factor of 2-3 followed by a steep drop from old (several Gyrs) field stars. This decline in activity beyond 300 Myr follows roughly t {sup –1}. Despite this clear evolution, there remains a wide range, of 1-2 orders of magnitude, in observed emission levels at every age. These UV data supply the much-needed constraints to M dwarf upper-atmosphere models, which will provide empirically motivated EUV predictions and more accurate age-dependent UV spectra as inputs to planetary photochemical models.

Oxygen isotope signature of UV degradation of glyphosate and phosphonoacetate: Tracing sources and cycling of phosphonates

Energy Technology Data Exchange (ETDEWEB)

Sandy, Edward H. [State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074 (China); Department of Geology and Geophysics, Yale University, P.O. Box 208109, New Haven, CT 06520-8109 (United States); Department of Chemistry, University of Sierra Leone, Freetown (Sierra Leone); Blake, Ruth E., E-mail: ruth.blake@yale.edu [Department of Geology and Geophysics, Yale University, P.O. Box 208109, New Haven, CT 06520-8109 (United States); School of Civil and Environmental Engineering, and National “International Cooperation Base on Environment and Energy”, University of Science and Technology Beijing, Beijing 100084 (China); Chang, Sae Jung [Department of Geology and Geophysics, Yale University, P.O. Box 208109, New Haven, CT 06520-8109 (United States); Jun, Yao, E-mail: yaojun@ustb.edu.cn [State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074 (China); Department of Geology and Geophysics, Yale University, P.O. Box 208109, New Haven, CT 06520-8109 (United States); School of Civil and Environmental Engineering, and National “International Cooperation Base on Environment and Energy”, University of Science and Technology Beijing, Beijing 100084 (China); Yu, Chan [Department of Geology and Geophysics, Yale University, P.O. Box 208109, New Haven, CT 06520-8109 (United States); School of Civil and Environmental Engineering, and National “International Cooperation Base on Environment and Energy”, University of Science and Technology Beijing, Beijing 100084 (China)

2013-09-15

Highlights: • Phosphonate (phon) hydrolysis by UVR (1.2 kW) attained ≥90% completion in 84 h. • Isotope study reveals both ambient H{sub 2}O and O{sub 2} involvements in phon C-P bond cleavage. • Mechanistic models proposed for phon C-P bond cleavage based on O-isotope analysis. • Model equations used to calculate δ{sup 18}O{sub P-org} of original phon P-moiety-useful as a tracer. • Study shows relevance in tracing phon sources and cycling in the environment. -- Abstract: The degradation of phosphonates in the natural environment constitutes a major route by which orthophosphate (Pi) is regenerated from organic phosphorus and recently implicated in marine methane production, with ramifications to environmental pollution issues and global climate change concerns. This work explores the application of stable oxygen isotope analysis in elucidating the C-P bond cleavage mechanism(s) of phosphonates by UV photo-oxidation and for tracing their sources in the environment. The two model phosphonates used, glyphosate and phosphonoacetic acid were effectively degraded after exposure to UV irradiation. The isotope results indicate the involvement of both ambient water and atmospheric oxygen in the C-P bond cleavage and generally consistent with previously posited mechanisms of UV-photon excitation reactions. A model developed to calculate the oxygen isotopic composition of the original phosphonate P-moiety, shows both synthetic phosphonates having distinctly lower values compared to naturally derived organophosphorus compounds. Such mechanistic models, based on O-isotope probing, are useful for tracing the sources and reactions of phosphonates in the environment.

Inhibitory effects of ambient levels of solar UV-A and UV-B radiation in growth of cv. New Red Fire lettuce

International Nuclear Information System (INIS)

Krizek, D.T.; Britz, S.J.; Mirecki, R.M.

1998-01-01

The influence of solar UV-A and UV-B radiation at Beltsville, MD, USA, on growth of Lactuca sativa L. (cv. New Red Fire lettuce) was examined during early summer of 1996 and 1997. Plants were grown from seed in plastic window boxes covered with Llumar to exclude UV-A and UV-B, polyester to exclude UV-B, or tefzel (1996) or teflon (1997) to transmit UV-A and UV-B radiation. After 31-34 days, plants grown in the absence of solar UV-B radiation (polyester) had 63 and 57% greater fresh weight and dry weight of tops, respectively, and 57, 72 and 47% greater dry weight of leaves, stems and roots, respectively, as compared to those grown under ambient UV-B (tefzel or teflon). Plants protected from UV-A radiation as well (Llumar) showed an additional 43 and 35% increase, respectively, in fresh and dry weight of tops and a 33 and 33% increase, respectively, in dry weight of leaves and stems, but no difference in root biomass over those grown under polyester. Excluding ambient UV-B (polyester) significantly reduced the UV absorbance of leaf extracts at 270, 300 and 330 nm (presumptive flavonoids) and the concentration of anthocyantins at 550 nm as compared to those of leaf extract from plants grown under ambient UV-A and UV-B. Additional removal of ambient UV-A (Llumar) reduced the concentration of anthocyanins, but had no further effect on UV absorbance at 270, 300 or 330 nm. These findings provide evidence that UV-B radiation is more important than UV-A radiation for flavonoid induction in this red-pigmented lettuce cultivar. Although previous workers have obtained decreases in lettuce yield under enhanced UV-B, this is the first evidence for inhibitory effects of solar UV-A and UV-B radiation on lettuce growth. (au)

Inhibitory effects of ambient levels of solar UV-A and UV-B radiation in growth of cv. New Red Fire lettuce

Energy Technology Data Exchange (ETDEWEB)

Krizek, D.T.; Britz, S.J.; Mirecki, R.M. [Climate Stress Laboratory, Beltsville, MD (United States)

1998-05-01

The influence of solar UV-A and UV-B radiation at Beltsville, MD, USA, on growth of Lactuca sativa L. (cv. New Red Fire lettuce) was examined during early summer of 1996 and 1997. Plants were grown from seed in plastic window boxes covered with Llumar to exclude UV-A and UV-B, polyester to exclude UV-B, or tefzel (1996) or teflon (1997) to transmit UV-A and UV-B radiation. After 31-34 days, plants grown in the absence of solar UV-B radiation (polyester) had 63 and 57% greater fresh weight and dry weight of tops, respectively, and 57, 72 and 47% greater dry weight of leaves, stems and roots, respectively, as compared to those grown under ambient UV-B (tefzel or teflon). Plants protected from UV-A radiation as well (Llumar) showed an additional 43 and 35% increase, respectively, in fresh and dry weight of tops and a 33 and 33% increase, respectively, in dry weight of leaves and stems, but no difference in root biomass over those grown under polyester. Excluding ambient UV-B (polyester) significantly reduced the UV absorbance of leaf extracts at 270, 300 and 330 nm (presumptive flavonoids) and the concentration of anthocyantins at 550 nm as compared to those of leaf extract from plants grown under ambient UV-A and UV-B. Additional removal of ambient UV-A (Llumar) reduced the concentration of anthocyanins, but had no further effect on UV absorbance at 270, 300 or 330 nm. These findings provide evidence that UV-B radiation is more important than UV-A radiation for flavonoid induction in this red-pigmented lettuce cultivar. Although previous workers have obtained decreases in lettuce yield under enhanced UV-B, this is the first evidence for inhibitory effects of solar UV-A and UV-B radiation on lettuce growth. (au) 34 refs.

Milk phospholipid's protective effects against UV damage in skin equivalent models

Science.gov (United States)

Dargitz, Carl; Russell, Ashley; Bingham, Michael; Achay, Zyra; Jimenez-Flores, Rafael; Laiho, Lily H.

2012-03-01

Exposure of skin tissue to UV radiation has been shown to cause DNA photodamage. If this damaged DNA is allowed to replicate, carcinogenesis may occur. DNA damage is prevented from being passed on to daughter cells by upregulation of the protein p21. p21 halts the cells cycle allowing the cell to undergo apoptosis, or repair its DNA before replication. Previous work suggested that milk phospholipids may possess protective properties against UV damage. In this study, we observed cell morphology, cell apoptosis, and p21 expression in tissue engineered epidermis through the use of Hematoxylin and Eosin staining, confocal microscopy, and western blot respectively. Tissues were divided into four treatment groups including: a control group with no UV and no milk phospholipid treatment, a group exposed to UV alone, a group incubated with milk phospholipids alone, and a group treated with milk phospholipids and UV. All groups were incubated for twenty-four hours after treatment. Tissues were then fixed, processed, and embedded in paraffin. Performing western blots resulted in visible p21 bands for the UV group only, implying that in every other group, p21 expression was lesser. Numbers of apoptotic cells were determined by observing the tissues treated with Hoechst dye under a confocal microscope, and counting the number of apoptotic and total cells to obtain a percentage of apoptotic cells. We found a decrease in apoptotic cells in tissues treated with milk phospholipids and UV compared to tissues exposed to UV alone. Collectively, these results suggest that milk phospholipids protect cell DNA from damage incurred from UV light.

UV Fluorescence Photography of Works of Art : Replacing the Traditional UV Cut Filters with Interference Filters

Directory of Open Access Journals (Sweden)

Luís BRAVO PEREIRA

2010-09-01

Full Text Available For many years filters like the Kodak Wratten E series, or the equivalent Schneider B+W 415, were used as standard UV cut filters, necessary to obtain good quality on UV Fluorescence photography. The only problem with the use of these filters is that, when they receive the UV radiation that they should remove, they present themselves an internal fluorescence as side effect, that usually reduce contrast and quality on the final image. This article presents the results of our experiences on using some innovative filters, that appeared available on the market in recent years, projected to adsorb UV radiation even more efficiently than with the mentioned above pigment based standard filters: the interference filters for UV rejection (and, usually, for IR rejection too manufactured using interference layers, that present better results than the pigment based filters. The only problem with interference filters type is that they are sensitive to the rays direction and, because of that, they are not adequate to wide-angle lenses. The internal fluorescence for three filters: the B+W 415 UV cut (equivalent to the Kodak Wratten 2E, pigment based, the B+W 486 UV IR cut (an interference type filter, used frequently on digital cameras to remove IR or UV and the Baader UVIR rejection filter (two versions of this interference filter were used had been tested and compared. The final quality of the UV fluorescence images seems to be of a superior quality when compared to the images obtained with classic filters.

Cerium oxide nanoparticles, combining antioxidant and UV shielding properties, prevent UV-induced cell damage and mutagenesis

KAUST Repository

Caputo, Fanny

2015-08-20

Efficient inorganic UV shields, mostly based on refracting TiO2 particles, have dramatically changed the sun exposure habits. Unfortunately, health concerns have emerged from the pro-oxidant photocatalytic effect of UV-irradiated TiO2, which mediates toxic effects on cells. Therefore, improvements in cosmetic solar shield technology are a strong priority. CeO2 nanoparticles are not only UV refractors but also potent biological antioxidants due to the surface 3+/4+ valency switch, which confers anti-inflammatory, anti-ageing and therapeutic properties. Herein, UV irradiation protocols were set up, allowing selective study of the extra-shielding effects of CeO2vs. TiO2 nanoparticles on reporter cells. TiO2 irradiated with UV (especially UVA) exerted strong photocatalytic effects, superimposing their pro-oxidant, cell-damaging and mutagenic action when induced by UV, thereby worsening the UV toxicity. On the contrary, irradiated CeO2 nanoparticles, via their Ce3+/Ce4+ redox couple, exerted impressive protection on UV-treated cells, by buffering oxidation, preserving viability and proliferation, reducing DNA damage and accelerating repair; strikingly, they almost eliminated mutagenesis, thus acting as an important tool to prevent skin cancer. Interestingly, CeO2 nanoparticles also protect cells from the damage induced by irradiated TiO2, suggesting that these two particles may also complement their effects in solar lotions. CeO2 nanoparticles, which intrinsically couple UV shielding with biological and genetic protection, appear to be ideal candidates for next-generation sun shields. © The Royal Society of Chemistry 2015.

Biological dosimetry to determine the UV radiation climate inside the MIR station and its role in vitamin D biosynthesis

Science.gov (United States)

Rettberg, P.; Horneck, G.; Zittermann, A.; Heer, M.

1998-11-01

The vitamin D synthesis in the human skin, is absolutely dependent on UVB radiation. Natural UVB from sunlight is normally absent in the closed environment of a space station like MIR. Therefore it was necessary to investigate the UV radiation climate inside the station resulting from different lamps as well as from occasional solar irradiation behind a UV-transparent quartz window. Biofilms, biologically weighting and integrating UV dosimeters successfully applied on Earth (e.g. in Antarctica) and in space (D-2, Biopan I) were used to determine the biological effectiveness of the UV radiation climate at different locations in the space station. Biofilms were also used to determine the personal UV dose of an individual cosmonaut. These UV data were correlated with the concentration of vitamin D in the cosmonaut's blood and the dietary vitamin D intake. The results showed that the UV radiation climate inside the Mir station is not sufficient for an adequate supply of vitamin D, which should therefore be secured either by vitamin D supplementat and/or by the regular exposure to special UV lamps like those in sun-beds. The use of natural solar UV radiation through the quartz window for `sunbathing' is dangerous and should be avoided even for short exposure periods.

Hybrid 2D patterning using UV laser direct writing and aerosol jet printing of UV curable polydimethylsiloxane

Science.gov (United States)

Obata, Kotaro; Schonewille, Adam; Slobin, Shayna; Hohnholz, Arndt; Unger, Claudia; Koch, Jürgen; Suttmann, Oliver; Overmeyer, Ludger

2017-09-01

The hybrid technique of aerosol jet printing and ultraviolet (UV) laser direct writing was developed for 2D patterning of thin film UV curable polydimethylsiloxane (PDMS). A dual atomizer module in an aerosol jet printing system generated aerosol jet streams from material components of the UV curable PDMS individually and enables the mixing in a controlled ratio. Precise control of the aerosol jet printing achieved the layer thickness of UV curable PDMS as thin as 1.6 μm. This aerosol jet printing system is advantageous because of its ability to print uniform thin-film coatings of UV curable PDMS on planar surfaces as well as free-form surfaces without the use of solvents. In addition, the hybrid 2D patterning using the combination of UV laser direct writing and aerosol jet printing achieved selective photo-initiated polymerization of the UV curable PDMS layer with an X-Y resolution of 17.5 μm.

Characterising and testing deep UV LEDs for use in space applications

International Nuclear Information System (INIS)

Hollington, D; Baird, J T; Sumner, T J; Wass, P J

2015-01-01

Deep ultraviolet (DUV) light sources are used to neutralise isolated test masses in highly sensitive space-based gravitational experiments. An example is the LISA Pathfinder charge management system, which uses low-pressure mercury lamps. A future gravitational-wave observatory such as eLISA will use UV light-emitting diodes (UV LEDs), which offer numerous advantages over traditional discharge lamps. Such devices have limited space heritage but are now available from a number of commercial suppliers. Here we report on a test campaign that was carried out to quantify the general properties of three types of commercially available UV LEDs and demonstrate their suitability for use in space. Testing included general electrical and UV output power measurements, spectral stability, pulsed performance and temperature dependence, as well as thermal vacuum, radiation and vibration survivability. (paper)

Characterising and testing deep UV LEDs for use in space applications

Science.gov (United States)

Hollington, D.; Baird, J. T.; Sumner, T. J.; Wass, P. J.

2015-12-01

Deep ultraviolet (DUV) light sources are used to neutralise isolated test masses in highly sensitive space-based gravitational experiments. An example is the LISA Pathfinder charge management system, which uses low-pressure mercury lamps. A future gravitational-wave observatory such as eLISA will use UV light-emitting diodes (UV LEDs), which offer numerous advantages over traditional discharge lamps. Such devices have limited space heritage but are now available from a number of commercial suppliers. Here we report on a test campaign that was carried out to quantify the general properties of three types of commercially available UV LEDs and demonstrate their suitability for use in space. Testing included general electrical and UV output power measurements, spectral stability, pulsed performance and temperature dependence, as well as thermal vacuum, radiation and vibration survivability.

Light-emitting Ga-oxide nanocrystals in glass: a new paradigm for low-cost and robust UV-to-visible solar-blind converters and UV emitters.

Science.gov (United States)

Sigaev, Vladimir N; Golubev, Nikita V; Ignat'eva, Elena S; Paleari, Alberto; Lorenzi, Roberto

2014-01-01

Wide-bandgap nanocrystals are an inexhaustible source of tuneable functions potentially addressing most of the demand for new light emitting systems. However, the implementation of nanocrystal properties in real devices is not straightforward if a robust and stable optical component is required as a final result. The achievement of efficient light emission from dense dispersions of Ga-oxide nanocrystals in UV-grade glass can be a breakthrough in this regard. Such a result would permit the fabrication of low cost UV-to-visible converters for monitoring UV-emitting events on a large-scale - from invisible hydrogen flames to corona dispersions. From this perspective, γ-Ga₂O₃ nanocrystals are developed by phase separation in Ga-alkali-germanosilicate glasses, obtaining optical materials based on a UV transparent matrix. Band-to-band UV-excitation of light emission from donor-acceptor pair (DAP) recombination is investigated for the first time in embedded γ-Ga₂O₃. The analysis of the decay kinetics gives unprecedented evidence that nanosized confinement of DAP recombination can force a nanophase to the efficient response of exactly balanced DAPs. The results, including a proof of concept of UV-to-visible viewer, definitely demonstrate the feasibility of workable glass-based fully inorganic nanostructured materials with emission properties borrowed from Ga₂O₃ single-crystals and tailored by the nanocrystal size.

New UV-curable acrylated polyester prepolymers from palm oil based products

International Nuclear Information System (INIS)

Mohd Azam Ali; Ooi, T.L.; Salmiah Ahmad; Umaru, S.I.; Mohd Ishak, Z.A.

1999-01-01

Acrylated polyester prepolymers (PEPP-1 and PEPP-2) were synthesized from palm oil and its products. UV-curing and characteristic properties of UV-cured films of synthesized polyester resins were studied. The characteristic properties studied include pendulum hardness, gel content, FT-IR analysis, tensile strength and elongation at break. The materials have good potential for the production of radiation curable coating applications

Relationship Between Landscape Character, UV Exposure, and Amphibian Decline

Science.gov (United States)

O'Reilly, C. M.; Brooks, P. D.; Corn, P. S.; Muths, E.; Campbell, D. H.; Diamond, S.; Tonnessen, K.

2001-12-01

Widespread reports of amphibian declines have been considered a warning of large-scale environmental degradation, yet the reasons for these declines remain unclear. This study suggests that exposure to ultraviolet radiation may act as an environmental stressor that affects population breeding success or susceptibility to disease. Ultraviolet radiation is attenuated by dissolved and particulate compounds in water, which may be of either terrestrial or aquatic origin. UV attenuation by dissolved organic carbon (DOC) is primarily due to compounds in the fulvic acid fraction, which originate in soil environments. These terrestrially-derived fulvic acids are transported to during hydrologic flushing events such as snowmelt and episodic precipitation and play an important role in controlling UV exposure in surface waters. As part of a previously published project, amphibian surveys were conducted at seventeen sites in Rocky Mountain National Park both during, and subsequent to, a three-year drought (1988 - 1990). During this period, ten sites lost one amphibian species, while only one site gained a previously unreported species. One possible explanation for these localized species losses is increased exposure to UV radiation, mediated by reduced terrestrial DOC inputs during dry periods. Several subsequent years of water chemistry data showed that the sites with documented species losses were characterized by a range of DOC concentrations, but tended to have a greater proportion of terrestrial DOC than sites that did not undergo species loss. This suggests that terrestrial inputs exert a strong control on DOC concentrations that may influence species success. We used physical environmental factors to develop a classification scheme for these sites. There are many physical factors that can influence terrestrial DOC inputs, including landscape position, geomorphology, soil type, and watershed vegetation. In addition, we considered the possible effects on internal aquatic

Factors affecting ultraviolet irradiation/hydrogen peroxide (UV/H2O2) degradation of mixed N-nitrosamines in water

International Nuclear Information System (INIS)

Zhou, Chao; Gao, Naiyun; Deng, Yang; Chu, Wenhai; Rong, Wenlei; Zhou, Shengdong

2012-01-01

Highlights: ► NAms with three-induced toxicity, as emerging DBPs, has caused a great public attention. ► No paper regards UV/H 2 O 2 oxidation of mixed NAms in an aquatic environment. ► The treatment effect is typically affected by a few factors in water. ► NPIP and NDPhA are the most readily and difficult to be degraded due to unique structure. ► All the NAms degradation exhibited a pseudo-first-order kinetics pattern. - Abstract: Disinfection by-products (DBPs) are a great challenge to our drinking water security. Particularly, nitrosamines (NAms), as emerging DBPs, are potently carcinogenic, mutagenic, and teratogenic, and have increasingly attained public attention. This study was to evaluate the performance of the NAms degradation by the ultraviolet (UV) irradiation (253.7 nm) in the presence of hydrogen peroxide (H 2 O 2 ). In the UV/H 2 O 2 system, hydroxyl radicals (OH·), a type of nonselective and powerful oxidant, was produced to attack the molecules of NAms. Factors affecting the treatment efficiency, including the H 2 O 2 dosage, initial NAms concentration, UV irradiation intensity, initial solution pH, and inorganic anions present in water, were evaluated. All the NAms degradation exhibited a pseudo-first-order kinetics pattern. Within 60 min, 0.1 mg/L of any NAms could be almost decomposed except NDPhA that required 120 min for complete removal, at 25 μmol/L H 2 O 2 and at initial pH 7. Results demonstrate that the UV/H 2 O 2 treatment is a viable option to control NAms in water.

Challenges for Life Support Systems in Space Environments, Including Food Production

Science.gov (United States)

Wheeler, Raymond M.

2012-01-01

Environmental Control and Life Support Systems (ECLSS) refer to the technologies needed to sustain human life in space environments. Histor ically these technologies have focused on providing a breathable atmo sphere, clean water, food, managing wastes, and the associated monitoring capabilities. Depending on the space agency or program, ELCSS has sometimes expanded to include other aspects of managing space enviro nments, such as thermal control, radiation protection, fire detection I suppression, and habitat design. Other times, testing and providing these latter technologies have been associated with the vehicle engi neering. The choice of ECLSS technologies is typically driven by the mission profile and their associated costs and reliabilities. These co sts are largely defined by the mass, volume, power, and crew time req uirements. For missions close to Earth, e.g., low-Earth orbit flights, stowage and resupply of food, some 0 2, and some water are often the most cost effective option. But as missions venture further into spa ce, e.g., transit missions to Mars or asteroids, or surface missions to Moon or Mars, the supply line economics change and the need to clos e the loop on life support consumables increases. These are often ref erred to as closed loop or regenerative life support systems. Regardless of the technologies, the systems must be capable of operating in a space environment, which could include micro to fractional g setting s, high radiation levels, and tightly closed atmospheres, including perhaps reduced cabin pressures. Food production using photosynthetic o rganisms such as plants by nature also provides atmospheric regenerat ion (e.g., CO2 removal and reduction, and 0 2 production), yet to date such "bioregenerative" technologies have not been used due largely t o the high power requirements for lighting. A likely first step in te sting bioregenerative capabilities will involve production of small a mounts of fresh foods to supplement to crew

Sun, UV Radiation and Your Eyes

Science.gov (United States)

... Sunglasses Sun Smart UV Safety Infographic The Sun, UV Radiation and Your Eyes Leer en Español: El ... Aug. 28, 2014 Keep an Eye on Ultraviolet (UV) Safety Eye medical doctors (ophthalmologists) caution us that ...

UV Photography Shows Hidden Sun Damage

Science.gov (United States)

... mcat1=de12", ]; for (var c = 0; c UV photography shows hidden sun damage A UV photograph gives ... developing skin cancer and prematurely aged skin. Normal photography UV photography 18 months of age: This boy's ...

The Aspergillus uvsH gene encodes a product homologous to yeast RAD18 and Neurospora UVS-2.

Science.gov (United States)

Yoon, J H; Lee, B J; Kang, H S

1995-07-28

The uvsH DNA repair gene of Aspergillus nidulans has been cloned by complementation of the uvsH77 mutation with a cosmid library containing genomic DNA inserts from a wild-type strain. Methylmethane sulfonate (MMS)-resistant transformants were obtained on medium containing 0.01% MMS, to which uvsH mutants exhibit high sensitivity. Retransformation of uvsH77 mutants with the rescued cosmids from the MMS-resistant transformants resulted in restoration of both UV and MMS resistance to wild-type levels. Nucleotide sequence analysis of the genomic DNA and cDNA of the uvsH gene shows that it has an open reading frame (ORF) of 1329 bp, interrupted by two introns of 51 and 61 bp. A 2.4 kb transcript of the uvsH gene was detected by Northern blot analysis. Primer extension analysis revealed that transcription starts at 31 bp upstream from the translation initiation codon. This gene encodes a predicted polypeptide of 443 amino acids, which has two unique zinc finger motifs. The proposed polypeptide displays 39% identity to the Neurospora crassa UVS-2 protein and 24% identity to the Saccharomyces cerevisiae RAD18 protein. The sequence similarity is particularly high in three domains. One zinc finger (RING finger) motif is located in the first domain close to the N-terminus. The other zinc finger motif is in the second domain. In the third domain, the mutation sites in both the uvsH77 and uvsH304 alleles were identified.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of different levels of UV-B radiation on marine epilithic communities: a short-term microcosm study

Directory of Open Access Journals (Sweden)

R. A. Danilov

2000-12-01

Full Text Available Epilithic communities from brackish coastal water of the east coast of Sweden were studied in order to reveal their responses to different levels of UV-B radiation. The experiment was conducted for seven days in an indoor microcosm system. The epilithic communities were exposed daily to different doses of UV-B radiation: 1, 3, 5 and 7 hours, respectively. The intensity of the UV-B radiation used was similar to that in natural environments. After seven days clear shifts both in species composition and community structure were observed. All species of diatoms showed negative correlation with enhanced levels of UV-B. On the other hand, abundance of cyanobacteria was positively correlated with enhanced levels of UV-B (Calothrix aeruginea, R=0.49;Oscillatoria amphibia, R=0.93; Pseudanabaena mucicola, R=0.26. Communities dominated by diatoms and green algae at the initial stage of the experiment did show a drastic decrease in diatom abundance under UV-B stress and finally became dominated by cyanobacteria. Among green algae the abundance of Cladophora sericea correlated positively (R=0.33 with enhanced exposure to UV-B, while Monoraphidium-species exhibited negative correlation to UV-B. Otherwise, no significant correlation between other green algae species identified and UV-B stress could be detected. We conclude that UV-B radiation, even at lower levels, is capable to induce severe changes to marine epilithic communities. The trends revealed in the present study predict a shift from communities dominated by diatoms and green algae to those dominated by cyanobacteria.

Time and Place as Modifiers of Personal UV Exposure

Directory of Open Access Journals (Sweden)

Brian L. Diffey

2018-05-01

Full Text Available It is a common belief that, if we want to limit our sun exposure during outdoor recreational activities and holidays in order to avoid sunburn or reduce our risk of skin cancer, we need to reach for the bottle of sunscreen or cover up with clothing. As important as these measures are, there is another way to enjoy our time outdoors and still benefit from the experience. In this article, we consider the impact of time, place, and behaviour outdoors on our exposure to solar ultraviolet (UV radiation. Some of the simple actions we can take in controlling our UV exposure include being aware of the position of the sun in the sky, understanding how we can use the UV index to guide our outdoor exposure, and the importance of reducing our sun exposure around the middle of the day. Finally we review our preferred holiday activities and destinations, and the influence of outdoor leisure pursuits. By planning where and when we spend our leisure time in the sun, we can maximise our enjoyment whilst limiting our UV exposure.

Time and Place as Modifiers of Personal UV Exposure.

Science.gov (United States)

Diffey, Brian L

2018-05-30

It is a common belief that, if we want to limit our sun exposure during outdoor recreational activities and holidays in order to avoid sunburn or reduce our risk of skin cancer, we need to reach for the bottle of sunscreen or cover up with clothing. As important as these measures are, there is another way to enjoy our time outdoors and still benefit from the experience. In this article, we consider the impact of time, place, and behaviour outdoors on our exposure to solar ultraviolet (UV) radiation. Some of the simple actions we can take in controlling our UV exposure include being aware of the position of the sun in the sky, understanding how we can use the UV index to guide our outdoor exposure, and the importance of reducing our sun exposure around the middle of the day. Finally we review our preferred holiday activities and destinations, and the influence of outdoor leisure pursuits. By planning where and when we spend our leisure time in the sun, we can maximise our enjoyment whilst limiting our UV exposure.

UV-LED Curing Efficiency of Wood Coatings

OpenAIRE

Véronic Landry; Pierre Blanchet; Gabrielle Boivin; Jean-François Bouffard; Mirela Vlad

2015-01-01

Ultraviolet light emitting diodes (UV-LEDs) have attracted great interest in recent years. They can be used to polymerize coatings, such as those used for prefinished wood flooring. In this project, two lamps were compared for their suitability to be used on a wood flooring finishing line: a UV-microwave and a UV-LED lamp. Low heat emission was found for the UV-LED lamp compared to the UV-microwave one. This study also reveals that the 4 W/cm2 UV-LED lamp used is not powerf...

Development and future of ultraviolet light-emitting diodes: UV-LED will replace the UV lamp

Science.gov (United States)

Muramoto, Yoshihiko; Kimura, Masahiro; Nouda, Suguru

2014-06-01

Ultraviolet light-emitting diodes (UV-LEDs) have started replacing UV lamps. The power per LED of high-power LED products has reached 12 W (14 A), which is 100 times the values observed ten years ago. In addition, the cost of these high-power LEDs has been decreasing. In this study, we attempt to understand the technologies and potential of UV-LEDs.

Effect of preparation and processing conditions on UV absorbing properties of hydroxyapatite-Fe2O3 sunscreen.

Science.gov (United States)

C Teixeira, M A; Piccirillo, C; Tobaldi, D M; Pullar, R C; Labrincha, J A; Ferreira, M O; L Castro, P M; E Pintado, M M

2017-02-01

The development of innovative, safe and non-photocatalytic sunscreens is urgently needed, as it is essential to have sunscreen filters offering appropriate UV protection without damaging the environment and/or generating free radicals when in contact with the skin. Hydroxyapatite (Ca 10 (PO 4 ) 6 (OH) 2 , HAp) when substituted with iron has UV protection properties and is not photocatalytic; HAp was used to make a sunscreen filter by treating cod fish bones in an iron-containing solution, and then calcining them at 700°C. Here we present a systematic and advanced study on this material, to obtain a sunscreen with improved UV absorbing properties. Bones were treated with three different iron salts - Fe(II) chloride, Fe(II) lactate and Fe(III) nitrate - under various pH conditions. Results showed that Fe(II) chloride in basic pH led to the most effective iron inclusion. High energy ball milling or ultrasound were investigated to increase surface area and corresponding UV absorption; high energy ball milling treatment led to the best optical properties. The optimum powders were used to formulate UV protection creams, which showed Sun Protection Factor (SPF) values significantly superior to the control cream (up to 4.1). Moreover the critical wavelength (λ crit ) was >370nm (388-389nm) and UVA/UVB ratios were very close to 1. With these properties these sunscreens can be classified as broad UV protectors. Results also showed that combining these powders with other sunscreens (i.e. titanium dioxide), a synergic effect between the different components was also observed. This investigation showed that HAp-based sunscreens of marine origin are a valid alternative to commercial products, safe for the health of the customers and, being non-photocatalytic, do not pose a threat to the environment. Copyright © 2016 Elsevier B.V. All rights reserved.

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.

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

Toxicokinetics and metabolisms of benzophenone-type UV filters in rats

International Nuclear Information System (INIS)

Jeon, Hee-Kyung; Sarma, Sailendra Nath; Kim, Youn-Jung; Ryu, Jae-Chun

2008-01-01

Sunscreens containing UV filters are recommended to reduce damage caused by solar UV radiation. Recently, benzophenone (BP)-type UV filters have become widely used as UV stabilizers in skin-moisturizing products and sunscreen lotions; however, very little information is available regarding the potential harmful effects of prolonged exposure to these compounds. Therefore, we investigated the toxicokinetics and metabolism of BP-type UV filters in rats using gas chromatography-mass spectrometry (GC-MS). To examine the metabolism of BP-type UV filters, we analyzed the parent compounds BP and 2-hydroxy-4-methoxybenzophenone (HMB). In rats, BP was mainly converted to benzhydrol (BH) and 4-hydroxybenzophenone (HBP) (i.e., type A UV filters). In contrast, HMB was converted into at least three intermediates, including 2,4-dihydroxybenzophenone (DHB), which was formed via o-demethylation and subsequently converted into 2,3,4-trihydroxybenzophenone (THB), and 2,2'-dihydroxy-4-methoxybenzophenone (DHMB), which formed via the aromatic hydroxylation of HMB (i.e., type B UV filters). Next, the toxicokinetic curve for BP showed a peak concentration (C max ) of 2.06 ± 0.46 μg/ml at approximately 4 h after BP administration. After a single oral dose of HMB, the C max of HMB reached 21.21 ± 11.61 μg/ml within 3 h (T max ), and then declined rapidly compared to the kinetic curve of BP. The concentration of these metabolites in rat blood decreased much more slowly over time compared to the parent compounds. Thus, our results indicate that such metabolites might have more significant adverse effects than the parent compounds over the long term

Effects of UV radiation on freshwater metazooplankton

International Nuclear Information System (INIS)

Tartarotti, B.

1999-06-01

There is evidence that fluxes of solar ultraviolet-B radiation (UV-B, 290-320 nm) are increasing over wide parts of the earth's surface due to stratospheric ozone depletion. UV radiation (290-400 nm) can have damaging effects on biomolecules and cell components that are common to most living organisms. The aim of this thesis is to gain a more thorough understanding of the potential impacts of solar radiation on freshwater metazooplankton. To detect UV-vulnerability in zooplankton populations dominating the zooplankton community of two clear-water, high mountain lakes located one in the Austrian Alps and another in the Chilean Andes, the survival of two copepod species was studied. The organisms were exposed to a 10- to 100-fold increase in UV-B radiation compared to those levels found at their natural, maximum daytime distribution. Both species vertically migrate and are pigmented. UV-absorbing compounds with a maximum absorption at ∼334 nm were also detected. Cyclops abyssorum tatricus, a common cyclopoid copepod species of Alpine lakes, was highly resistant to UV-B radiation and no significant lethal effect was observed. The calanoid copepod Boeckella gracilipes, frequent in Andean lakes, had a mortality ∼5 times higher in the treatment receiving full sunlight than in the UV-B excluded treatment (3.2 %) only when exposed for 70 h. The resistance of B. gracilipes was higher than that reported in the literature for the same species suggesting the existence of intraspecific differences in UV sensitivity. Survival, fecundity and development of the zooplankton community of a clear-water, high elevation Andean lake (33 o S) were studied with mesocosms experiments after prolonged UV exposure (48 days). When exposed to full sunlight, the population of the cladoceran Chydorus sphaericus and the rotifer Lepadella ovalis were strongly inhibited by UV-B, whereas both species were resistant to UV-A radiation. Conversely, UV-B radiation had no effect on the survival of the

INACTIVATION OF PATHOGENIC BACTERIA USING PULSED UV-LIGHT AND ITS APPLICATION IN WATER DISINFECTION AND QUALITY CONTROL

Directory of Open Access Journals (Sweden)

M. K. Sharifi-Yazdi H. Darghahi

2006-09-01

Full Text Available The lethality of pulsed ultra-violet (UV rich light for the inactivation of pathogenic bacteria has been investigated. A low pressure xenon filled flash lamps that produced UV intensities have been used. The pulsed operation of the system enable the release of electrical energy stored in the capacitor into the flash lamp within a short time and produces the high current and high peak power required for emitting the intense UV flash. The flash frequency was adjusted to one pulse per second. Several types of bacteria were investigated for their susceptibility to pulsed UV illumination. The treated bacterial populations were reduced and determined by direct viable counts. Among the tested bacteria Pseudomonas aeruginosa was the most susceptible to the pulsed UV- light with a 8 log10 cfu/ml reduction after 11 pulses, while the spores of Bacillus megaterium was the most resistant and only 4 log10 cfu/ml reduction achieved after 50 pulses of illumination. The results of this study demonstrated that pulsed UV- light technology could be used as an effective method for the inactivation, of pathogenic bacteria in different environments such as drinking water.

High Power UV LED Industrial Curing Systems

Energy Technology Data Exchange (ETDEWEB)

Karlicek, Robert, F., Jr; Sargent, Robert

2012-05-14

UV curing is a green technology that is largely underutilized because UV radiation sources like Hg Lamps are unreliable and difficult to use. High Power UV LEDs are now efficient enough to replace Hg Lamps, and offer significantly improved performance relative to Hg Lamps. In this study, a modular, scalable high power UV LED curing system was designed and tested, performing well in industrial coating evaluations. In order to achieve mechanical form factors similar to commercial Hg Lamp systems, a new patent pending design was employed enabling high irradiance at long working distances. While high power UV LEDs are currently only available at longer UVA wavelengths, rapid progress on UVC LEDs and the development of new formulations designed specifically for use with UV LED sources will converge to drive more rapid adoption of UV curing technology. An assessment of the environmental impact of replacing Hg Lamp systems with UV LED systems was performed. Since UV curing is used in only a small portion of the industrial printing, painting and coating markets, the ease of use of UV LED systems should increase the use of UV curing technology. Even a small penetration of the significant number of industrial applications still using oven curing and drying will lead to significant reductions in energy consumption and reductions in the emission of green house gases and solvent emissions.

UV disinfection of water

International Nuclear Information System (INIS)

Skipperud, E.; Johansen; Myhrstad, J.A.

1978-01-01

UV radiation has been found to have advantages over chloration for the disinfection of water. New regulations for dietary conditions on Norwegian ships introduced in 1974 led to increased use of UV disinfection, and this has in the following years spread to waterworks. The present article is based on a study to determine possible limitation. The nature of the injuries to the microorganisms is first discussed, together with repair mechanisms. A table is given showing the energy required for 90 and 100 percent inactivation of a number of microorganisms. Some other factors affecting UV inactivation are briefly mentioned. (JIW)

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...

Energy Effectiveness of Direct UV and UV/H2O2 Treatment of Estrogenic Chemicals in Biologically Treated Sewage

DEFF Research Database (Denmark)

Hansen, Kamilla Marie Speht; Andersen, Henrik Rasmus

2012-01-01

and the UV/H2O2-treatment were investigated in biologically treated sewage for most of the estrogenic compounds reported in wastewater. The investigated compounds included parabens, industrial phenols, sunscreen chemicals and steroid estrogens. Treatment experiments were performed in a flow through set...

Seasonal responses of six Poaceae to differential levels of solar UV-B radiation

International Nuclear Information System (INIS)

Deckmyn, G.; Impens, I.

1999-01-01

The effects of changes in solar UV-B on the growth and pigmentation of six grass species from cold-temperate grasslands (Lolium perenne, Lolium multiflorum, Festuca arundinacea, Festuca rubra, Phleum pratense and Dactylis glomerata) in spring and summer were studied. The grasses were grown in greenhouses with different foils, resulting in three treatments: no UV-B, 80% of ambient and 90% of ambient UV-BBE (biologically effective UV-B). The results indicated important effects of ambient UV-B levels on grass, but the different species reacted in very different ways. Both morphology and biomass production were influenced by UV-B in some species. However, changes in biomass production did not necessarily occur within the same species as changes in morphology. The grasses were more sensitive in summer. Overall, only F. rubra was positively influenced by UV-B under all circumstances. The biomass of D. glomerata and L. perenne was reduced by UV-B in spring and summer. Morphological changes included reduced height and increased tillering. The sensitivity of the different species was partially explained by their ability to reduce their specific leaf area in response to UV-B. Only the more sensitive species showed increased production of protective pigments. Overall, there were important differences between the effect of a low level of UV-B, and the further increase in UV-B, indicating that several mechanisms are operating at different light levels. (author)

UV-A enhanced growth and UV-B induced positive effects in the recovery of photochemical yield in Gracilaria lemaneiformis (Rhodophyta).

Science.gov (United States)

Xu, Juntian; Gao, Kunshan

2010-09-02

The effects of solar UV radiation (280-400 nm) on growth, quantum yield and pigmentation in Gracilaria lemaneiformis were investigated when the thalli were cultured under solar radiation with or without UV for a period of 15 days. Presence of UV-A (315-400 nm) enhanced the relative growth rate, while UV-B (218-315 nm) inhibited it. The positive effect of UV-A and negative effect of UV-B counteracted to result in an insignificant impact of UVR on growth. During the noon period, both UV-A and UV-B resulted in the decrease of maximum quantum yield (Fv/Fm), but UV-B aided in the recovery of the yield in the late afternoon, reflecting that UV-B might be used as a signal in photorepair processes. UV induced the accumulation of UV-absorbing compounds (UVAC) to defend against the harmful UVR. However, the accumulation of UVAC took a much longer time compared to that previously reported, which was probably due to the lower levels of solar radiation and water temperature in the early spring period. Unknown UV-absorbing compounds (UVAC), which peaked at 265 nm, probably the precursor of MAAs (UVAC(325)), accumulated under moderate levels of solar radiation and were transformed to MAAs under higher solar radiation. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Kinetic study on UV-absorber photodegradation under different conditions

Energy Technology Data Exchange (ETDEWEB)

Bubev, Emil, E-mail: ebubev@my.uctm.edu [University of Chemical Technology and Metallurgy, Department of Physical Chemistry (Bulgaria); Georgiev, Anton [University of Chemical Technology and Metallurgy, Department of Organic Chemistry (Bulgaria); Machkova, Maria [University of Chemical Technology and Metallurgy, Department of Physical Chemistry (Bulgaria)

2016-09-12

The photodegradation kinetics of two benzophenone derivative UV-absorbers (UVAs)-BP-4 (benzophenone-4) and 4-HBP (4-hydroxybenzophenone), as additives in polyvinyl acetate (PVAc) films, were studied. Solution-processed PVAc films were irradiated in different environments in order to study oxygen and atmospheric humidity influence on UVA photodegradation. Photodegradation was traced by absorption intensity loss via UV–vis spectroscopy. Both UVAs exhibited excellent photostability in an inert atmosphere. Rate constants showed that BP-4 has better permanence in absence of oxygen. Both film types experienced rapid absorption loss, when irradiated in an oxygen containing atmosphere. UVA degradation was treated as a two-stage process. The photodegradation kinetics in the first stage agreed with the adopted complex rate law, but the second stage was best described by pseudo-first order kinetics. BP-4 exhibited better stability. Oxygen was established as the main accelerating factor for photodegradation of benzophenone derivatives UV-absorbers in thin PVAc films.

Microbial Response to UV Exposure and Nitrogen Limitation in Desert Soil Crusts

Science.gov (United States)

Fulton, J. M.; Van Mooy, B. A.

2016-12-01

Microbiotic soil crusts have diverse biomarker distributions and C and N stable isotopic compositions that covary with soil type. Sparse plant cover and the relative lack of soil disturbance in arid/semi-arid landscapes allows populations of soil cyanobacteria to develop along with fungi and heterotrophic bacteria. Microbial communities in this extreme environment depend in part on the production of scytonemin, a UV protective pigment, by cyanobacteria near the top of the crust. N limitation of microbial growth also affects soil crust population dynamics, increasing the requirement of N2fixation by diazotrophic cyanobacteria. We collected 56 soil crust samples from 27 locations throughout the Great Salt Lake Desert, including four transects spanning high-elevation, erosion-dominated soils to lower elevation soils dominated by silt-accumulation. Erosion-dominated soil surfaces included rounded gravel and cobbles; in the interstices there were poorly-developed microbiotic crusts on sandy loam with low δ15N values near 0‰ that point toward microbial growth dependent on cyanobacterial N2 fixation. Nutrients regenerated by heterotrophic bacteria may have been eroded from the system, providing a positive feedback for N2 fixation. High scytonemin:chlorophyll a ratios suggest that cyanobacteria required enhanced protection from UV damage in these crusts. A similar increase in scytonemin:chlorophyll a ratio during soil crust rehydration experiments also points toward the importance of UV protection. Glycolipid:phospholipid ratios were lowest where N2 fixation was favored, however, suggesting that the cyanobacterial population was relatively small, possibly because of the metabolic cost of N2fixation. Microbiotic crusts on silt loam soils, on the other hand, had higher δ15N values between 3.5 and 7.8‰, consistent with heterotrophic growth and nutrient recycling. Lower scytonemin:chlorophyll a ratios suggest that relatively high photosynthetic activity was supported in

Solar UV exposure among outdoor workers in Denmark measured with personal UV-B dosimeters: technical and practical feasibility.

Science.gov (United States)

Grandahl, Kasper; Mortensen, Ole Steen; Sherman, David Zim; Køster, Brian; Lund, Paul-Anker; Ibler, Kristina Sophie; Eriksen, Paul

2017-10-10

Exposure to solar ultraviolet radiation is a well-known cause of skin cancer. This is problematic for outdoor workers. In Denmark alone, occupational skin cancer poses a significant health and safety risk for around 400,000 outdoor workers. Objective measures of solar ultraviolet radiation exposure are needed to help resolve this problem. This can be done using personal ultraviolet radiation dosimeters. We consider technical and practical feasibility of measuring individual solar ultraviolet exposure at work and leisure in professions with different á priori temporal high-level outdoor worktime, using aluminium gallium nitride (AlGaN) photodiode detector based personal UV-B dosimeters. Essential technical specifications including the spectral and angular responsivity of the dosimeters are described and pre-campaign dosimeter calibration applicability is verified. The scale and conduct of dosimeter deployment and campaign in-field measurements including failures and shortcomings affecting overall data collection are presented. Nationwide measurements for more than three hundred and fifty workers from several different professions were collected in the summer of 2016. On average, each worker's exposure was measured for a 2-week period, which included both work and leisure. Data samples of exposure at work during a Midsummer day show differences across professions. A construction worker received high-level occupational UV exposure most of the working day, except during lunch hour, accumulating to 5.1 SED. A postal service worker was exposed intermittently around noon and in the afternoon, preceded by no exposure forenoon when packing mail, accumulating to 1.6 SED. A crane fitter was exposed only during lunch hour, accumulating to 0.7 SED. These findings are in line with our specialist knowledge as occupational physicians. Large-scale use of personal UV-B dosimeters for measurement of solar ultraviolet radiation exposure at work and leisure in Denmark is indeed

Development and future of ultraviolet light-emitting diodes: UV-LED will replace the UV lamp

International Nuclear Information System (INIS)

Muramoto, Yoshihiko; Kimura, Masahiro; Nouda, Suguru

2014-01-01

Ultraviolet light-emitting diodes (UV-LEDs) have started replacing UV lamps. The power per LED of high-power LED products has reached 12 W (14 A), which is 100 times the values observed ten years ago. In addition, the cost of these high-power LEDs has been decreasing. In this study, we attempt to understand the technologies and potential of UV-LEDs. (invited article)

[UV Protection Law. Enhancing the protection of minors against health risks from solaria].

Science.gov (United States)

Riemer, M

2006-12-01

The article reports on a petition to the German Bundestag in the field of UV protection for persons under the age of 18 against the dangers of artificial sunbed tanning for cosmetic purposes. On 16 March 2006 the Parliament agreed to adopt the proposal of the author, after the Ministry of Environment announced it is working on a UV Protection Law for Germany. Furthermore the committee recommended the petition to the government and the parliamentary parties. The UV Protection Law is still in progress, and no draft has yet been published. Therefore, the author explains the difficulties in creating such law from a legal and a public health perspective, pointing out that the split of competence between the federation and the states poses difficulties. He concludes that the German Constitution would allow a sunbed prohibition for minors in public studios and explains why a complete prohibition for the adult population would be disproportionate and unconstitutional.

Degradation of diclofenac by UV-activated persulfate process: Kinetic studies, degradation pathways and toxicity assessments.

Science.gov (United States)

Lu, Xian; Shao, Yisheng; Gao, Naiyun; Chen, Juxiang; Zhang, Yansen; Xiang, Huiming; Guo, Youluo

2017-07-01

Diclofenac (DCF) is the frequently detected non-steroidal pharmaceuticals in the aquatic environment. In this study, the degradation of DCF was evaluated by UV-254nm activated persulfate (UV/PS). The degradation of DCF followed the pseudo first-order kinetics pattern. The degradation rate constant (k obs ) was accelerated by UV/PS compared to UV alone and PS alone. Increasing the initial PS dosage or solution pH significantly enhanced the degradation efficiency. Presence of various natural water constituents had different effects on DCF degradation, with an enhancement or inhibition in the presence of inorganic anions (HCO 3 - or Cl - ) and a significant inhibition in the presence of NOM. In addition, preliminary degradation mechanisms and major products were elucidated using LC-MS/MS. Hydroxylation, decarbonylation, ring-opening and cyclation reaction involving the attack of SO 4 • - or other substances, were the main degradation mechanism. TOC analyzer and Microtox bioassay were employed to evaluate the mineralization and cytotoxicity of solutions treated by UV/PS at different times, respectively. Limited elimination of TOC (32%) was observed during the mineralization of DCF. More toxic degradation products and their related intermediate species were formed, and the UV/PS process was suitable for removing the toxicity. Of note, longer degradation time may be considered for the final toxicity removal. Copyright © 2017. Published by Elsevier Inc.

High-Performance Visible-Blind UV Phototransistors Based on n-Type Naphthalene Diimide Nanomaterials.

Science.gov (United States)

Song, Inho; Lee, Seung-Chul; Shang, Xiaobo; Ahn, Jaeyong; Jung, Hoon-Joo; Jeong, Chan-Uk; Kim, Sang-Wook; Yoon, Woojin; Yun, Hoseop; Kwon, O-Pil; Oh, Joon Hak

2018-04-11

This study investigates the performance of single-crystalline nanomaterials of wide-band gap naphthalene diimide (NDI) derivatives with methylene-bridged aromatic side chains. Such materials are found to be easily used as high-performance, visible-blind near-UV light detectors. NDI single-crystalline nanoribbons are assembled using a simple solution-based process (without solvent-inclusion problems), which is then applied to organic phototransistors (OPTs). Such OPTs exhibit excellent n-channel transistor characteristics, including an average electron mobility of 1.7 cm 2 V -1 s -1 , sensitive UV detection properties with a detection limit of ∼1 μW cm -2 , millisecond-level responses, and detectivity as high as 10 15 Jones, demonstrating the highly sensitive organic visible-blind UV detectors. The high performance of our OPTs originates from the large face-to-face π-π stacking area between the NDI semiconducting cores, which is facilitated by methylene-bridged aromatic side chains. Interestingly, NDI-based nanoribbon OPTs exhibit a distinct visible-blind near-UV detection with an identical detection limit, even under intense visible light illumination (for example, 10 4 times higher intensity than UV light intensity). Our findings demonstrate that wide-band gap NDI-based nanomaterials are highly promising for developing high-performance visible-blind UV photodetectors. Such photodetectors could potentially be used for various applications including environmental and health-monitoring systems.

UV-straling in de kas: mogelijkheden en grenzen

NARCIS (Netherlands)

Hoffmann, S.

2000-01-01

Effect van UV-straling op kleuring van Coleus Blumei 'Wizzard Velvit Red'. Gegevens in bijgaande tabellen: 1) Indeling optische straling; 2) Transmisse voor UV-straling van verschillende dekmaterialen (folie UV, glas UV, glas normaal, folie normaal, folie UV-blok

UV-activated persulfate oxidation and regeneration of NOM-Saturated granular activated carbon.

Science.gov (United States)

An, Dong; Westerhoff, Paul; Zheng, Mengxin; Wu, Mengyuan; Yang, Yu; Chiu, Chao-An

2015-04-15

A new method of ultraviolet light (UV) activated persulfate (PS) oxidation was investigated to regenerate granular activated carbon (GAC) in drinking water applications. The improvements in iodine and methylene blue numbers measured in the GAC after ultraviolet- (UV) activated persulfate suggested that the GAC preloaded with natural organic matter (NOM) was chemically regenerated. An experimental matrix for UV-activated persulfate regeneration included a range of persulfate doses and different UV wavelengths. Over 87% of the initial iodine number for GAC was restored under the optimum conditions, perfulfate dosage 60 g/L and UV exposure 1.75 × 10(4) mJ/cm(2). The persulfate dosages had little effect on the recovery of the methylene blue number, which was approximately 65%. Persulfate activation at 185 nm was superior to activation at 254 nm. UV activation of persulfate in the presence of GAC produced acid, lowering the solution pH. Higher persulfate concentrations and UV exposure resulted in greater GAC regeneration. Typical organic and inorganic byproducts (e.g., benzene compounds and sulfate ions) were measured as a component of treated water quality safety. This study provides a proof-of-concept that can be used to optimize pilot-scale and full-scale UV-activated persulfate for regeneration of NOM-saturated GAC. Copyright © 2015 Elsevier Ltd. All rights reserved.

UV writing of advanced Bragg gratings in optical waveguides

DEFF Research Database (Denmark)

Jensen, Jesper Bo Damm

2002-01-01

of the novel polarization control method for UV writing of Bragg gratings with advanced apodization profiles including phase shifts. The principle of the polarization control method relies on a spatial separation of the s- and p-polarized components of a linearly polarized UV beam corresponding to half......, Technical University of Denmark. During fabrication the planar waveguides were annealed in an oxygen rich atmosphere. This reduces the photosensitivity to a negligible level and Bragg gratings cannot be written within reasonable time unless the waveguides are sensitized by deuterium loading. Samples were...

Application of UV-irradiated Fe(III)-nitrilotriacetic acid (UV-Fe(III)NTA) and UV-NTA-Fenton systems to degrade model and natural occurring naphthenic acids.

Science.gov (United States)

Zhang, Ying; Chelme-Ayala, Pamela; Klamerth, Nikolaus; Gamal El-Din, Mohamed

2017-07-01

Naphthenic acids (NAs) are a highly complex mixture of organic compounds naturally present in bitumen and identified as the primary toxic constituent of oil sands process-affected water (OSPW). This work investigated the degradation of cyclohexanoic acid (CHA), a model NA compound, and natural occurring NAs during the UV photolysis of Fe(III)-nitrilotriacetic acid (UV-Fe(III)NTA) and UV-NTA-Fenton processes. The results indicated that in the UV-Fe(III)NTA process at pH 8, the CHA removal increased with increasing NTA dose (0.18, 0.36 and 0.72 mM), while it was independent of the Fe(III) dose (0.09, 0.18 and 0.36 mM). Moreover, the three Fe concentrations had no influence on the photolysis of the Fe(III)NTA complex. The main responsible species for the CHA degradation was hydroxyl radical (OH), and the role of dissolved O 2 in the OH generation was found to be negligible. Real OSPW was treated with the UV-Fe(III)NTA and UV-NTA-Fenton advanced oxidation processes (AOPs). The removals of classical NAs (O 2 -NAs), oxidized NAs with one additional oxygen atom (O 3 -NAs) and with two additional oxygen atoms (O 4 -NAs) were 44.5%, 21.3%, and 25.2% in the UV-Fe(III)NTA process, respectively, and 98.4%, 86.0%, and 81.0% in the UV-NTA-Fenton process, respectively. There was no influence of O 2 on the NA removal in these two processes. The results also confirmed the high reactivity of the O 2 -NA species with more carbons and increasing number of rings or double bond equivalents. This work opens a new window for the possible treatment of OSPW at natural pH using these AOPs. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hydrodynamic simulation of X-UV laser-produced plasmas

International Nuclear Information System (INIS)

Fajardo, M.; Zeitoun, P.; Gauthier, J.C.

2004-01-01

With the construction of novel X-UV sources, such as V-UV FEL's (free-electron lasers), X-UV laser-matter interaction will become available at ultra-high intensities. But even table-top facilities such as X-UV lasers or High Harmonic Generation, are starting to reach intensities high enough to produce dense plasmas. X-UV laser-matter interaction is studied by a 1-dimensional hydrodynamic Lagrangian code with radiative transfer for a range of interesting X-UV sources. Heating is found to be very different for Z=12-14 elements having L-edges around the X-UV laser wavelength. Possible absorption mechanisms were investigated in order to explain this behaviour, and interaction with cold dense matter proved to be dominant. Plasma sensitivity to X-UV laser parameters such as energy, pulse duration, and wavelength was also studied, covering ranges of existing X-UV lasers. We found that X-UV laser-produced plasmas could be studied using table-top lasers, paving the way for future V-UV-FEL high intensity experiments. (authors)

Simultaneous energy generation and UV quencher removal from landfill leachate using a microbial fuel cell.

Science.gov (United States)

Iskander, Syeed Md; Novak, John T; Brazil, Brian; He, Zhen

2017-11-01

The presence of UV quenching compounds in landfill leachate can negatively affect UV disinfection in a wastewater treatment plant when leachate is co-treated. Herein, a microbial fuel cell (MFC) was investigated to remove UV quenchers from a landfill leachate with simultaneous bioelectricity generation. The key operating parameters including hydraulic retention time (HRT), anolyte recirculation rate, and external resistance were systematically studied to maximize energy recovery and UV absorbance reduction. It was found that nearly 50% UV absorbance was reduced under a condition of HRT 40 days, continuous anolyte recirculation, and 10 Ω external resistance. Further analysis showed a total reduction of organics by 75.3%, including the reduction of humic acids, fulvic acids, and hydrophilic fraction concentration as TOC. The MFC consumed 0.056 kWh m -3 by its pump system for recirculation and oxygen supply. A reduced HRT of 20 days with periodical anode recirculation (1 hour in every 24 hours) and 39 Ω external resistance (equal to the internal resistance of the MFC) resulted in the highest net energy of 0.123 kWh m -3 . Granular activated carbon (GAC) was used as an effective post-treatment step and could achieve 89.1% UV absorbance reduction with 40 g L -1 . The combined MFC and GAC treatment could reduce 92.9% of the UV absorbance and remove 89.7% of the UV quenchers. The results of this study would encourage further exploration of using MFCs as an energy-efficient method for removing UV quenchers from landfill leachate.

Cytoprotective effect against UV-induced DNA damage and oxidative stress: role of new biological UV filter.

Science.gov (United States)

Said, T; Dutot, M; Martin, C; Beaudeux, J-L; Boucher, C; Enee, E; Baudouin, C; Warnet, J-M; Rat, P

2007-03-01

The majority of chemical solar filters are cytotoxic, particularly on sensitive ocular cells (corneal and conjunctival cells). Consequently, a non-cytotoxic UV filter would be interesting in dermatology, but more especially in ophthalmology. In fact, light damage to the eye can be avoided thanks to a very efficient ocular antioxidant system; indeed, the chromophores absorb light and dissipate its energy. After middle age, a decrease in the production of antioxidants and antioxidative enzymes appears with accumulation of endogenous molecules that are phototoxic. UV radiations can induce reactive oxygen species formation, leading to various ocular diseases. Because most UV filters are cytotoxic for the eye, we investigated the anti-UV properties of Calophyllum inophyllum oil in order to propose it as a potential vehicle, free of toxicity, with a natural UV filter action in ophthalmic formulation. Calophyllum inophyllum oil, even at low concentration (1/10,000, v/v), exhibited significant UV absorption properties (maximum at 300nm) and was associated with an important sun protection factor (18-22). Oil concentrations up to 1% were not cytotoxic on human conjunctival epithelial cells, and Calophyllum inophyllum oil appeared to act as a cytoprotective agent against oxidative stress and DNA damage (85% of the DNA damage induced by UV radiations were inhibited with 1% Calophyllum oil) and did not induce in vivo ocular irritation (Draize test on New Zealand rabbits). Calophyllum inophyllum oil thus exhibited antioxidant and cytoprotective properties, and therefore might serve, for the first time, as a natural UV filter in ophthalmic preparations.

Ozone layer - climate change interactions. Influence on UV levels and UV related effects

NARCIS (Netherlands)

Kelfkens G; Bregman A; de Gruijl FR; van der Leun JC; Piquet A; van Oijen T; Gieskes WWC; van Loveren H; Velders GJM; Martens P; Slaper H; NOP; LPI; LLO

2002-01-01

Ozone in the atmosphere serves as a partially protective filter against the most harmful part of the solar UV-spectrum. Decreases in ozone lead to increases in ambient UV with a wide variety of adverse effects on human health, aquatic and terrestrial ecosystems and food chains. Human health

Decolorization of direct poly azo dye with nanophotocatalytic UV/NiO process

Directory of Open Access Journals (Sweden)

Ali Assadi

2012-01-01

Full Text Available Aims: The aim of the present study is to investigate the efficiency of ultraviolet/ nickel oxide (UV/NiO system as one form of advanced oxidation processes (AOP for decolorization of red poly azo. Materials and Methods: This study was conducted as a laboratory scale in a batch mode. Ultraviolet radiation was provided by a low pressure (11 W UV lamp. Effects of various factors including pH, different irradiation durations, different concentration of nickel oxide, and initial dye concentration were evaluated. Results: The results of the UV/NiO system′s assessment showed that UV light alone cannot remove DR 80 dye. Nickel oxide is an effective catalyst in the decolorization of dye with the nanophotocatalytic process. The decolorization efficiency increases with decreasing pH value and the optimum pH value is 4. Fainally, the highest removal efficiency achieved by UV/NiO process for DR 80 dye with concentrations of 25 mg/l and 50 mg/l was 94.3% and 82.2%, respectively. UV/NiO-based decolorization process follows pseudo-second-order reaction kinetics. Conclusions: From the findings of the present study, it can be concluded that UV/NiO process is an effective technique for decolorization of poly azo dye, DR 80, in aqueous solutions.

UV-Heat Treatments for the Control of Foodborne Microbial Pathogens in Chicken Broth

Directory of Open Access Journals (Sweden)

M. Gouma

2015-01-01

Full Text Available This investigation established the process criteria for using UV-C light and mild heat (UV-H treatment to inactivate 5-Log10 cycles (performance criterion of common foodborne pathogen populations, Escherichia coli, Salmonella Typhimurium, Listeria monocytogenes, and Staphylococcus aureus, when inoculated in chicken broth. To define the target microorganism and the proper UV-H treatment conditions (including UV dose, treatment time, and temperature that would achieve the stated performance criterion, mathematical equations based on Geeraerd’s model were developed for each microorganism. For the sake of comparison, inactivation equations for heat treatments were also performed on the same chicken broth and for the same microorganisms. L. monocytogenes was the most UV-H resistant microorganism at all temperatures, requiring a UV dose between 6.10 J/mL (5.6 min and 2.26 J/mL (2.09 min to achieve 5-Log10 reductions. In comparison with UV treatments at room temperatures, the combination of UV and mild heat allowed both the UV dose and treatment time to be reduced by 30% and 63% at 55°C and 60°C, respectively. Compared to heat treatments, the UV-H process reduced the heating time for 5-Log10 reductions of all the investigated microorganisms in chicken broth from 20-fold to 2-fold when the operating temperature varied from 53 to 60°C.

A European satellite-derived UV climatology available for impact studies

International Nuclear Information System (INIS)

Verdebout, J.

2004-01-01

This paper presents a satellite-derived climatology of the surface UV radiation, intended to support impact studies on the environment and human health. As of today, the dataset covers the period from 1 January 1984 to 31 August 2003, with daily dose maps covering Europe with a spatial resolution of 0.05 deg.. A comparison between the modelled erythemal daily dose and measurements in Ispra yields an r.m.s value with a relative difference of 29% and a bias of 3%. The seemingly large dispersion is, however, due to a restricted number of days for which the relative difference is very high. The climatological dataset documents systematic patterns in the geographical distribution of the surface UV radiation due to cloudiness, altitude and snow. It also shows a large year-to-year variability in monthly doses of up to ±50% in spring and ±30% in summer. (authors)

Perchlorates on Mars enhance the bacteriocidal effects of UV light.

Science.gov (United States)

Wadsworth, Jennifer; Cockell, Charles S

2017-07-06

Perchlorates have been identified on the surface of Mars. This has prompted speculation of what their influence would be on habitability. We show that when irradiated with a simulated Martian UV flux, perchlorates become bacteriocidal. At concentrations associated with Martian surface regolith, vegetative cells of Bacillus subtilis in Martian analogue environments lost viability within minutes. Two other components of the Martian surface, iron oxides and hydrogen peroxide, act in synergy with irradiated perchlorates to cause a 10.8-fold increase in cell death when compared to cells exposed to UV radiation after 60 seconds of exposure. These data show that the combined effects of at least three components of the Martian surface, activated by surface photochemistry, render the present-day surface more uninhabitable than previously thought, and demonstrate the low probability of survival of biological contaminants released from robotic and human exploration missions.

Distinct UV-B and UV-A/blue light signal transduction pathways induce chalcone synthase gene expression in Arabidopsis cells

International Nuclear Information System (INIS)

Christie, J.M.; Jenkins, G.I.

1996-01-01

UV and blue light control the expression of flavonoid biosynthesis genes in a range of higher plants. To investigate the signal transduction processes involved in the induction of chalcone synthase (CHS) gene expression by UV-B and UV-A/blue light, we examined the, effects of specific agonists and inhibitors of known signaling components in mammalian systems in a photomixotrophic Arabidopsis cell suspension culture. CHS expression is induced specifically by these wavelengths in the cell culture, in a manner similar to that in mature Arabidopsis leaf tissue. Both the UV-B and UV-A/blue phototransduction processes involve calcium, although the elevation of cytosolic calcium is insufficient on its own to stimulate CHS expression. The UV-A/blue light induction of CHS expression does not appear to involve calmodulin, whereas the UV-B response does; this difference indicates that the signal transduction pathways are, at least in part, distinct. We provide evidence that both pathways involve reversible protein phosphorylation and require protein synthesis. The UV-B and UV-A/blue light signaling pathways are therefore different from the phytochrome signal transduction pathway regulating CHS expression in other species

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□.

Comparison of UV-LED and low pressure UV for water disinfection: Photoreactivation and dark repair of Escherichia coli.

Science.gov (United States)

Li, Guo-Qiang; Wang, Wen-Long; Huo, Zheng-Yang; Lu, Yun; Hu, Hong-Ying

2017-12-01

Studies on ultraviolet light-emitting diode (UV-LED) water disinfection have shown advantages, such as safety, flexible design, and lower starting voltages. However, information about reactivation after UV-LED disinfection is limited, which is an important issue of UV light-based technology. In this study, the photoreactivation and dark repair of Escherichia coli after UV-LEDs and low pressure (LP) UV disinfection were compared. Four UV-LED units, 265 nm, 280 nm, the combination of 265 + 280 (50%), and 265 + 280 (75%) were tested. 265 nm LEDs was more effective than 280 nm LEDs and LP UV lamps for E. coli inactivation. No synergic effect for disinfection was observed from the combination of 265 and 280 nm LEDs. 265 nm LEDs had no different reactivation performances with that of LP UV, while 280 nm LEDs could significantly repress photoreactivation and dark repair at a low irradiation intensity of 6.9 mJ/cm 2 . Furthermore, the UV-induced damage of 280 nm LEDs was less repaired which was determined by endonuclease sensitive site (ESS) assay. The impaired protein activities by 280 nm LEDs might be one of the reasons that inhibited reactivation. A new reactivation rate constant, K max , was introduced into the logistic model to simulate the reactivation data, which showed positive relationship with the maximum survival ratio and was more reasonable to interpret the results of photoreactivation and dark repair. This study revealed the distinct roles of different UV lights in disinfection and reactivation, which is helpful for the future design of UV-LED equipment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Ambient solar UV radiation and seasonal trends in potential sunburn ...

African Journals Online (AJOL)

Background. The detrimental effects of excess personal solar ultraviolet (UV) radiation exposure include sunburn, immunosuppression and skin cancer. In South Africa, individuals with minimum natural protection from melanin, including fair-skinned individuals and African albinos, and people spending extended ...

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.

A DEVICE AND METHOD FOR MEASURING TAR IN A TAR-ENVIRONMENT