WorldWideScience

Sample records for decreased uv light

  1. Sunscreens with broad-spectrum absorption decrease the trans TO cis photoisomerization of urocanic acid in the human stratum corneum after multiple UV light exposures

    International Nuclear Information System (INIS)

    Krien, P.M.; Moyal, D.

    1994-01-01

    The trans to cis photoisomerization of urocanic acid (UCA) in skin is considered to play an important role in the mechanism of immunosuppression. We have investigated the effects of skin type and various sunscreens with low sun protection factor (SPF) on the UV-induced cis-UCA formation in human skin after exposure to artificial UV light. The rate of cis-UCA formation depends little on the skin type and is reduced by topical application of sunscreens. The rate of cis-UCA formation decreases with increasing SPF and only broad-spectrum, highly protective sunscreens offer protection against the UV-induced formation of cis-UCA, which accumulates in the stratum corneum after multiple UV exposures. A theoretical approach to estimate the distribution of cis-UCA after irradiation indicates that this compound may diffuse into the deeper layers of the epidermis with D ∼ 10 -17 m 2 /s, and that its elimination from the stratum corneum is mainly due to desquamation. (author)

  2. Bactericidal effectiveness of modulated UV light

    International Nuclear Information System (INIS)

    Bank, H.L.; John, J.; Schmehl, M.K.; Dratch, R.J.

    1990-01-01

    Studies were designed to evaluate the effectiveness of pulsed modulated UV light waveforms for killing bacteria. Exposure of five strains of bacteria to the modulated information encoded in the light decreased the colony population from a confluent lawn to less than 20 colonies. However, approximately 2,000 colonies survived treatment with the same intensity and time of exposure to UV light lacking the modulated information

  3. UV Light Induces Dedoping of Polyaniline

    Directory of Open Access Journals (Sweden)

    Yuki Kaitsuka

    2016-01-01

    Full Text Available UV (Ultra-Violet light-driven change in optical absorption of polyaniline (PANI is reported. Irradiation of UV light to PANI/camphor sulfonic acid prepared by electrochemical polymerization allows dedoping of the PANI. Especially, UV light irradiation in the presence of a radical trap agent effectively reduces (dedoping the PANI. The result in this study is quite simple; however, this may be a first report for light-induced dedoping (color change of a conductive polymer.

  4. Decreased UV light resistance of spores of Bacillus subtilis strains deficient in pyrimidine dimer repair and small, acid-soluble spore proteins

    International Nuclear Information System (INIS)

    Setlow, B.; Setlow, P.

    1988-01-01

    Loss of small, acid-soluble spore protein alpha reduced spore UV resistance 30- to 50-fold in Bacillus subtilis strains deficient in pyrimidine dimer repair, but gave only a 5- to 8-fold reduction in UV resistance in repair-proficient strains. However, both repair-proficient and -deficient spores lacking this protein had identical heat and gamma-radiation resistance

  5. 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□.

  6. 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

  7. Daily light integral and day light quality: Potentials and pitfalls of nighttime UV treatments on cucumber powdery mildew.

    Science.gov (United States)

    Suthaparan, Aruppillai; Solhaug, Knut Asbjørn; Stensvand, Arne; Gislerød, Hans Ragnar

    2017-10-01

    Nighttime ultraviolet (UV) radiation, if applied properly, has a significant potential for management of powdery mildews in many crop species. In this study, the role of growth light duration, irradiance, a combination of both (daily light integral) and light spectral quality (blue or red) on the efficacy of UV treatments against powdery mildew caused by Podosphaera xanthii and the growth performance of cucumber plants was studied in growth chambers. Increasing daily light integral provided by high-pressure sodium lamps (HPS) decreased efficacy of nighttime UV treatments against P. xanthii, but it increased plant growth. Furthermore, the efficacy of nighttime UV decreased when day length was increased from 16 to 20h at a constant daily light integral. The efficacy of nighttime UV increased if red light was applied after UV treatment, showing the possibility of day length extension without reducing the effect of UV. Increasing the dose of blue light during daytime reduced the efficacy of nighttime UV in controlling the disease, whereas blue deficient growth light (light after nighttime UV reduced its disease control efficacy. This showed the importance of maintaining a minimum of blue light in the growth light before nighttime UV treatment. Findings from this study showed that optimization of nighttime UV for management of powdery mildew is dependent on the spectral composition of the photosynthetically active radiation. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. UV filters for lighting of plants

    Energy Technology Data Exchange (ETDEWEB)

    Doehring, T.; Koefferlein, M.; Thiel, S.; Seidlitz, H.K.; Payer, H.D. [GSF-Forschungszentrum fuer Umwelt und Gesundheit GmbH, Oberschleissheim (Germany)

    1994-12-31

    Different filter glasses are available which provide absorption properties suitable for gradual changes of the spectral UV-B illumination of artificial lighting. Using a distinct set of lamps and filter glasses an acceptable simulation of the UV-B part of natural global radiation can be achieved. The ageing of these and other filter materials under the extreme UV radiation in the lamphouse of a solar simulator is presently unavoidable. This instability can be dealt with only by a precise spectral monitoring and by replacing the filters accordingly. For this reason attempts would be useful to develop real ozone filters which can replace glass filters. In any case chamber experiments require a careful selection of the filter material used and must be accompanied by a continuous UV-B monitoring.

  9. 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.

  10. 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)

  11. 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.

  12. Fluorescence image excited by a scanning UV-LED light

    Science.gov (United States)

    Tsai, Hsin-Yi; Chen, Yi-Ju; Huang, Kuo-Cheng

    2013-03-01

    An optical scanning system using UV-LED light to induced fluorescence technology can enhance a fluorescence image significantly in a short period. It has several advantages such as lower power consumption, no scattering effect in skins, and multilayer images can be obtained to analyze skin disease. From the experiment results, the light intensity increases with increase spot size and decrease scanning speed, but the image resolution is oppositely. Moreover, the system could be widely used in clinical diagnosis and photodynamic therapy for skin disease because even the irradiated time of fluorescence substance is short but it will provide accurately positioning of fluorescence object.

  13. Dependence of UV effect on quality of light during raising of seedlings (Lactuca sativa L.)

    International Nuclear Information System (INIS)

    Bogenrieder, A.; Klein, R.

    1978-01-01

    Greenhouse seedlings of Lactuca sativa L. show a decreased rate of photosynthesis under normal outdoor light conditions due to the effect of UV-light. In this study, the relationship between the declining rate of photosynthesis and the amount of UV in the spectrum was investigated. The determination was made in climatized gas exchange chambers under Xenon arc lamps (XBO 2500 W, Osram). The amount of UV in the spectrum was varied by the use of different surface mirrors made by aluminium evaporation. A linear relationship between the amount of UV-light in the spectrum and the rate of decrease of photosynthesis was obtained with 12 hour radiation. The decrease in photosynthesis is less when the plants are raised under UV-light lamps. (orig.) [de

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

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  15. People with Increased Risk of Eye Damage from UV Light

    Science.gov (United States)

    ... With Increased Risk of Eye Damage from UV Light Leer en Español: Algunas Personas Están en Mayor Riesgo de Sufrir Daño Ocular por los Rayos UV Written By: Shirley Dang Apr. 30, 2014 Everyone of any age and any degree of skin pigmentation is susceptible to UV damage. Children are ...

  16. Carcinogenesis related to intense pulsed light and UV exposure

    DEFF Research Database (Denmark)

    Hedelund, L; Lerche, C; Wulf, H C

    2006-01-01

    This study examines whether intense pulsed light (IPL) treatment has a carcinogenic potential itself or may influence ultraviolet (UV)-induced carcinogenesis. Secondly, it evaluates whether UV exposure may influence IPL-induced side effects. Hairless, lightly pigmented mice (n=144) received three...

  17. [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.

  18. Carcinogenesis related to intense pulsed light and UV exposure

    DEFF Research Database (Denmark)

    Hedelund, L; Lerche, C; Wulf, H C

    2006-01-01

    This study examines whether intense pulsed light (IPL) treatment has a carcinogenic potential itself or may influence ultraviolet (UV)-induced carcinogenesis. Secondly, it evaluates whether UV exposure may influence IPL-induced side effects. Hairless, lightly pigmented mice (n=144) received three...... observation period. Side effects were evaluated clinically. No tumors appeared in untreated control mice or in just IPL-treated mice. Skin tumors developed in UV-exposed mice independently of IPL treatments. The time it took for 50% of the mice to first develop skin tumor ranged from 47 to 49 weeks...... in preoperative UV-exposed mice (p=0.94) and from 22 to 23 weeks in pre- and postoperative UV-exposed mice (p=0.11). IPL rejuvenation of lightly pigmented skin did not induce pigmentary changes (p=1.00). IPL rejuvenation of UV-pigmented skin resulted in an immediate increased skin pigmentation and a subsequent...

  19. UV emissions from low energy artificial light sources.

    Science.gov (United States)

    Fenton, Leona; Moseley, Harry

    2014-01-01

    Energy efficient light sources have been introduced across Europe and many other countries world wide. The most common of these is the Compact Fluorescent Lamp (CFL), which has been shown to emit ultraviolet (UV) radiation. Light Emitting Diodes (LEDs) are an alternative technology that has minimal UV emissions. This brief review summarises the different energy efficient light sources available on the market and compares the UV levels and the subsequent effects on the skin of normal individuals and those who suffer from photodermatoses. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  20. Fundamental Scaling of Microplasmas and Tunable UV Light Generation.

    Energy Technology Data Exchange (ETDEWEB)

    Manginell, Ronald P. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sillerud, Colin Halliday [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hopkins, Matthew M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Yee, Benjamin Tong [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Moorman, Matthew W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Schwindt, Peter [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Anderson, John Moses [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Pfeifer, Nathaniel Bryant [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-11-01

    The temporal evolution of spectral lines from microplasma devices (MD) was studied, including impurity transitions. Long-wavelength emission diminishes more rapidly than deep UV with decreasing pulse width and RF operation. Thus, switching from DC to short pulsed or RF operation, UV emissions can be suppressed, allowing for real-time tuning of the ionization energy of a microplasma photo-ionization source, which is useful for chemical and atomic physics. Scaling allows MD to operate near atmospheric pressure where excimer states are efficiently created and emit down to 65 nm; laser emissions fall off below 200 nm, making MD light sources attractive for deep UV use. A first fully-kinetic three-dimensional model was developed that explicitly calculates electron-energy distribution function. This, and non-continuum effects, were studied with the model and how they are impacted by geometry and transient or DC operation. Finally, a global non-dimensional model was developed to help explain general trends MD physics.

  1. Skin β-Endorphin Mediates Addiction to UV Light

    OpenAIRE

    Fell, Gillian L.; Robinson, Kathleen C.; Mao, Jianren; Woolf, Clifford J.; Fisher, David E.

    2014-01-01

    Ultraviolet light is an established carcinogen yet evidence suggests that UV-seeking behavior has addictive features. Following UV exposure, epidermal keratinocytes synthesize Proopiomelanocortin that is processed to Melanocyte Stimulating Hormone, inducing tanning. We show that in rodents another POMC-derived peptide, β-endorphin, is coordinately synthesized in skin, elevating plasma levels after low-dose UV. Increases in pain-related thresholds are observed, and reversed by pharmacologic op...

  2. Solar UV light regulates flavonoid metabolism in apple (Malus x domestica).

    Science.gov (United States)

    Henry-Kirk, Rebecca A; Plunkett, Blue; Hall, Miriam; McGhie, Tony; Allan, Andrew C; Wargent, Jason J; Espley, Richard V

    2018-03-01

    Ultraviolet-B light (UV-B) is one environmental signal perceived by plants that affects the flavonoid pathway and influences the levels of anthocyanins, flavonols, and proanthocyanidins. To understand the mechanisms underlying UV exposure, apple trees were grown under spectral filters that altered transmission of solar UV light. Fruit analysis showed that UV induced changes in physiology, metabolism, and gene expression levels during development over a season. These changes were sustained after storage. Under low UV, ripening was delayed, fruit size decreased, and anthocyanin and flavonols were reduced. Expression analysis showed changes in response to UV light levels for genes in the regulation and biosynthesis of anthocyanin and flavonols. Transcription of flavonol synthase (FLS), ELONGATED HYPOCOTYL 5 (HY5), MYB10, and MYB22 were down-regulated throughout fruit development under reduced UV. Functional testing showed that the FLS promoter was activated by HY5, and this response was enhanced by the presence of MYB22. The MYB22 promoter can also be activated by the anthocyanin regulator, MYB10. As ambient levels of UV light vary around the globe, this study has implications for future crop production, the quality of which can be determined by the response to UV. © 2018 John Wiley & Sons Ltd.

  3. Light-like noncommutativity, light-front quantization and new light on UV/IR mixing

    International Nuclear Information System (INIS)

    Sheikh-Jabbari, M.M.; Tureanu, A.

    2011-01-01

    We revisit the problem of quantizing field theories on noncommutative Moyal space-time with light-like noncommutativity. To tackle the issues arising from noncommuting and hence nonlocal time, we argue that for this case light-front quantization procedure should be employed. In this appropriate quantization scheme we perform the non-planar loop analysis for the light-like noncommutative field theories. One of the important and peculiar features of light-front quantization is that the UV cutoff of the light-cone Hamiltonian manifests itself as an IR cutoff for the light-cone momentum, p + . Due to this feature, the naive results of covariant quantization for the light-like case allude to the absence of the UV/IR mixing in the light-front quantization. However, by a careful analysis of non-planar loop integrals we show that this is not the case and the UV/IR mixing persists. In addition, we argue in favour of the perturbative unitarity of light-like noncommutative field theories in the light-front quantization scheme.

  4. 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)

  5. Response of human epidermal keratinocytes to UV light

    International Nuclear Information System (INIS)

    Kartasova, A.A.

    1987-01-01

    This thesis presents a study on the response of human epidermal keratinocytes to UV light as well as to other agents like 4-NQO and TPA. The effects of ultraviolet (UV) light on the protein synthesis in cultured keratinocytes are presented in ch. III. The next chapter describes the construction of a cDNA library using mRNA isolated from UV irradiated kernatinocytes. This library was differentially screened with cDNA probes synthesized on mRNA from either UV irradiated or nonirradiated cells. Several groups of cDNA clones corresponding to transcripts whose level in the cytoplasm seem to be affected by exposure to UV light have been isolated and characterized by cross-hybridization, sequencing and Northern blot analysis. More detailed analysis of some of the cDNA clones is presented in the two chapters following ch. IV. The complete cDNA sequence of the proteinase inhibitor cystatin A and the modulation of its expression by UV light and the carcinogen 4-nitroquinoline 1-oxide (4-NQO) in keratinocytes are described in ch. V. Two other groups of cDNA clones have been isolated which do not cross-hybridize with each other on Southern blots. However, the primary structures of the proteins deduced from the nucleotide sequences of these two groups of cDNA clones are very similar. 212 refs.; 33 figs.; 2 tabs

  6. Effects of UV light and chromium ions on wood flavonoids

    International Nuclear Information System (INIS)

    Molnárné Hamvas, L.; Németh, K.; Stipta, J.

    2003-01-01

    The individual and simultaneous effect of UV light and chromium ions was investigated by spectrophotometric methods on inert surfaces impregnated with quercetin or robinetin. The UV-VIS spectra of the silica gel plates impregnated with these flavonoids were modified characteristically after irradiating ultraviolet light. Even a half an hour of irradiation has caused irreversible changes in the molecule structure. A certain chemical - presumably complexation - was concluded from the change of spectral bands assigned to flavonoids when impregnated with chromic ions. Hexavalent chromium caused more complex changes in the absorption spectra. The differences in the spectra could indicate either the oxidation and decomposition of flavonoids, or some kind of coordination process and the reduction of hexavalent chromium. The simultaneous application of UV light and chromium ions caused more pronounced effects. The complexation process between chromium(III) and flavonoid was completed

  7. 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

  8. 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.

  9. Ambient UV-B radiation decreases photosynthesis in high arctic Vaccinium uliginosum

    DEFF Research Database (Denmark)

    Albert, Kristian Rost; Mikkelsen, Teis Nørgaard; Ro-Poulsen, H.

    2008-01-01

    ). Leaf area, biomass, carbon, nitrogen and UV-B-absorbing compounds were determined from a late season harvest. Compared with the reduced UV-B treatment, the plants in ambient UV-B were found to have a higher content of UV-B-absorbing compounds, and canopy net photosynthesis was as an average 23% lower...... during the season. By means of the JIP-test, it was found that the potential of processing light energy through the photosynthetic machinery was slightly reduced in ambient UV-B. This indicates that not only the UV-B effects on PSII may be responsible for some of the observed reduction of photosynthesis...... on photosynthesis clearly indicates that V. uliginosum is negatively affected by the current level of UV-B....

  10. Large area UV light source with a semiconductor cathode

    International Nuclear Information System (INIS)

    Salamov, B. G.; Ciftci, Y. Oe.; Colakoglu, K.

    2002-01-01

    The light emission (LE) in the UV and visible (blue) range generated by a planar gas discharge system (PGDS) with a semiconductor cathode (SC) are studied. New light source offer high-intensity narrow-band emission at various UV and visible wavelengths (330 - 440 nm). Spectra in N 2 is presented, as well as intensity vs pressure curves for the main peaks of the spectrum. The use of source offers several advantages: PGDS can be extremely efficient energy converters transforming and amplifying a relatively low-powered photon flux incident on the receiving surface of the SC into a flux of high-energy particles over extended areas, i.e. electron, ions, photons. Thus, extremely bright UV and visible sources can be built. LE characteristics of the space in the PGDS are complex, depending on the emitting medium and species. By using the IR light to excite the SC of the system, we have shown that the discharge light emission (DLE) of the device with the N 2 in the gap can serve as an efficient source of the UV radiation if gas pressure and electric field are sufficiently high. This is realized due to the effect of the stabilisation of the spatially homogeneous mode of the discharge in a narrow gap with a large emitting area of SC. Special features of DLE render it highly promising for the development of sources with a large area of the emitting surface, high spatial uniformity of UV radiation, and fast dynamics of these devices. This low cost, high power light sources can provide an interesting alternative to conventional UV lamps

  11. Skin β-endorphin mediates addiction to UV light.

    Science.gov (United States)

    Fell, Gillian L; Robinson, Kathleen C; Mao, Jianren; Woolf, Clifford J; Fisher, David E

    2014-06-19

    UV light is an established carcinogen, yet evidence suggests that UV-seeking behavior has addictive features. Following UV exposure, epidermal keratinocytes synthesize proopiomelanocortin (POMC) that is processed to melanocyte-stimulating hormone, inducing tanning. We show that, in rodents, another POMC-derived peptide, β-endorphin, is coordinately synthesized in skin, elevating plasma levels after low-dose UV. Increases in pain-related thresholds are observed and reversed by pharmacologic opioid antagonism. Opioid blockade also elicits withdrawal signs after chronic UV exposure. This effect was sufficient to guide operant behavioral choices to avoidance of opioid withdrawal (conditioned place aversion). These UV-induced nociceptive and behavioral effects were absent in β-endorphin knockout mice and in mice lacking p53-mediated POMC induction in epidermal keratinocytes. Although primordial UV addiction, mediated by the hedonic action of β-endorphin and anhedonic effects of withdrawal, may theoretically have enhanced evolutionary vitamin D biosynthesis, it now may contribute to the relentless rise in skin cancer incidence in humans. Copyright © 2014 Elsevier Inc. All rights reserved.

  12. Conformational Effects of UV Light on DNA Origami.

    Science.gov (United States)

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

    2017-02-01

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

  13. UV light blocks EGFR signalling in human cancer cell lines

    DEFF Research Database (Denmark)

    Olsen, BB; Neves-Petersen, M T; Klitgaard, S

    2007-01-01

    UV light excites aromatic residues, causing these to disrupt nearby disulphide bridges. The EGF receptor is rich in aromatic residues near the disulphide bridges. Herein we show that laser-pulsed UV illumination of two different skin-derived cancer cell lines i.e. Cal-39 and A431, which both...... antibodies. There was a threshold level, below which the receptor could not be blocked. In addition, illumination caused the cells to upregulate the cyclin-dependent kinase inhibitor p21WAF1, irrespective of the p53 status. Since the EGF receptor is often overexpressed in cancers and other proliferative skin...... disorders, it might be possible to significantly reduce the proliferative potential of these cells making them good targets for laser-pulsed UV light treatment....

  14. Ambient UV-B radiation decreases photosynthesis in high arctic Vaccinium uliginosum

    Energy Technology Data Exchange (ETDEWEB)

    Albert, K.R.; Ro-Poulsen, H. (Univ. of Copenhagen, Dept. of Terrestrial Ecology, Copenhagen (DK)); Mikkelsen, T.N. (Technical Univ. of Denmark, Risoe National Laboratory for Sustainable Energy, Biosystems Dept., Roskilde (DK))

    2008-06-15

    An UV-B-exclusion experiment was established in high arctic Zackenberg, Northeast Greenland, to investigate the possible effects of ambient UV-B on plant performance. During almost a whole growing season, canopy gas exchange and Chl fluorescence were measured on Vaccinium uliginosum (bog blueberry). Leaf area, biomass, carbon, nitrogen and UV-B-absorbing compounds were determined from a late season harvest. Compared with the reduced UV-B treatment, the plants in ambient UV-B were found to have a higher content of UV-B-absorbing compounds, and canopy net photosynthesis was as an average 23% lower during the season. By means of the JIP-test, it was found that the potential of processing light energy through the photosynthetic machinery was slightly reduced in ambient UV-B. This indicates that not only the UV-B effects on PSII may be responsible for some of the observed reduction of photosynthesis but also the effects on other parts of the photosynthetic machinery, e.g. the Calvin cycle, might be important. The 60% reduction of the UV-B irradiance used in this study implies a higher relative change in the UV-B load than many of the supplemental experiments do, but the substantial effect on photosynthesis clearly indicates that V. uliginosum is negatively affected by the current level of UV-B. (au)

  15. Ambient UV-B radiation decreases photosynthesis in high arctic Vaccinium uliginosum.

    Science.gov (United States)

    Albert, Kristian R; Mikkelsen, Teis N; Ro-Poulsen, Helge

    2008-06-01

    An UV-B-exclusion experiment was established in high arctic Zackenberg, Northeast Greenland, to investigate the possible effects of ambient UV-B on plant performance. During almost a whole growing season, canopy gas exchange and Chl fluorescence were measured on Vaccinium uliginosum (bog blueberry). Leaf area, biomass, carbon, nitrogen and UV-B-absorbing compounds were determined from a late season harvest. Compared with the reduced UV-B treatment, the plants in ambient UV-B were found to have a higher content of UV-B-absorbing compounds, and canopy net photosynthesis was as an average 23% lower during the season. By means of the JIP-test, it was found that the potential of processing light energy through the photosynthetic machinery was slightly reduced in ambient UV-B. This indicates that not only the UV-B effects on PSII may be responsible for some of the observed reduction of photosynthesis but also the effects on other parts of the photosynthetic machinery, e.g. the Calvin cycle, might be important. The 60% reduction of the UV-B irradiance used in this study implies a higher relative change in the UV-B load than many of the supplemental experiments do, but the substantial effect on photosynthesis clearly indicates that V. uliginosum is negatively affected by the current level of UV-B.

  16. UV-A/blue-light responses in algae

    Energy Technology Data Exchange (ETDEWEB)

    Senger, H.; Hermsmeier, D. [Philipps-Universitaet Marburg (Germany)

    1994-12-31

    All life on earth depends on light. A variety of photoreceptors capture the light for a wide range of reactions. Photosynthetic organisms absorb the light necessary for energy transformation and charge separation facilitating photosynthesis. In addition to the bulk pigments there are a great diversity of photoreceptors present in minute concentrations that control development, metabolism and orientation of plants and microorganisms. Based on its spectral absorbance, the well-studied phytochrome system acts in the RL region as well as in the UV-A/BL region where the above mentioned reactions are mediated by a variety of photoreceptors whose natures are largely unknown. Phyllogenetically the UV-A/BL photoreceptors seem to be more ancient pigments that eventually were replaced by the phytochrome system. However, there are many reports that suggest a coaction between the UV-A/BL receptors and the phytochrome system. In several cases the UV-A/BL activation is the prerequisite for the phytochrome reaction. Historically it was the German botanist Julius Sachs who first discovered in 1864 that phototropism in plants was due to BL reactions. It took over 70 years until Bunning (1937) and Galston and Baker (1949) rediscovered the BL response. Since then, an ever-increasing attention has been paid to this effect. Two international conferences in 1979 and 1983 have been entirely dedicated to the BL phenomenon. In this contribution, the general aspect of UV-A/BL responses and especially the responsiveness of algae will be covered. There are numerous review articles covering the various aspects of UV-A/BL action and the photoreceptors involved.

  17. 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

  18. 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

  19. Blind haste: As light decreases, speeding increases.

    Science.gov (United States)

    de Bellis, Emanuel; Schulte-Mecklenbeck, Michael; Brucks, Wernher; Herrmann, Andreas; Hertwig, Ralph

    2018-01-01

    Worldwide, more than one million people die on the roads each year. A third of these fatal accidents are attributed to speeding, with properties of the individual driver and the environment regarded as key contributing factors. We examine real-world speeding behavior and its interaction with illuminance, an environmental property defined as the luminous flux incident on a surface. Drawing on an analysis of 1.2 million vehicle movements, we show that reduced illuminance levels are associated with increased speeding. This relationship persists when we control for factors known to influence speeding (e.g., fluctuations in traffic volume) and consider proxies of illuminance (e.g., sight distance). Our findings add to a long-standing debate about how the quality of visual conditions affects drivers' speed perception and driving speed. Policy makers can intervene by educating drivers about the inverse illuminance‒speeding relationship and by testing how improved vehicle headlights and smart road lighting can attenuate speeding.

  20. Luminescence- and nanoparticle-mediated increase of light absorption by photoreceptor cells: Converting UV light to visible light

    OpenAIRE

    Li, Lei; Sahi, Sunil K.; Peng, Mingying; Lee, Eric B.; Ma, Lun; Wojtowicz, Jennifer L.; Malin, John H.; Chen, Wei

    2016-01-01

    We developed new optic devices ? singly-doped luminescence glasses and nanoparticle-coated lenses that convert UV light to visible light ? for improvement of visual system functions. Tb3+ or Eu3+ singly-doped borate glasses or CdS-quantum dot (CdS-QD) coated lenses efficiently convert UV light to 542?nm or 613?nm wavelength narrow-band green or red light, or wide-spectrum white light, and thereby provide extra visible light to the eye. In zebrafish (wild-type larvae and adult control animals,...

  1. 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

  2. Blind haste: As light decreases, speeding increases.

    Directory of Open Access Journals (Sweden)

    Emanuel de Bellis

    Full Text Available Worldwide, more than one million people die on the roads each year. A third of these fatal accidents are attributed to speeding, with properties of the individual driver and the environment regarded as key contributing factors. We examine real-world speeding behavior and its interaction with illuminance, an environmental property defined as the luminous flux incident on a surface. Drawing on an analysis of 1.2 million vehicle movements, we show that reduced illuminance levels are associated with increased speeding. This relationship persists when we control for factors known to influence speeding (e.g., fluctuations in traffic volume and consider proxies of illuminance (e.g., sight distance. Our findings add to a long-standing debate about how the quality of visual conditions affects drivers' speed perception and driving speed. Policy makers can intervene by educating drivers about the inverse illuminance‒speeding relationship and by testing how improved vehicle headlights and smart road lighting can attenuate speeding.

  3. Current schemes for National Synchrotron Light Source UV beamlines

    International Nuclear Information System (INIS)

    Williams, G.P.; Howells, M.R.; McKinney, W.R.

    1979-01-01

    We describe in some detail four beamlines proposed for the National Synchrotron Light Source uv ring at Brookhaven National Laboratory. Three grazing-incidence instruments, one of the plane grating Mijake type and two with toroidal gratings at grazing angles of 2-1/2 0 and 15 0 are described. Two normal incidence instruments, one using the source as entrance slit and accepting 75 milliradians horizontally are also discussed. In each case we have estimated the output fluxes expected from such beamlines

  4. UV light induced DNA damages and the radiation protection effects of Lingzi mushroom extract

    International Nuclear Information System (INIS)

    Vo Thi Thuong Lan; Dinh Ba Tuan; Ta Bich Thuan; Tran Bang Diep; Tran Minh Quynh

    2016-01-01

    UV light has strongly influenced on the growth of E. coli as well as caused DNA damages. Configurations of both genomic DNA and pUC 19 plasmids extracted from E. coli were significantly changed by the exposure to UV light of 254 nm and DLT, an extract of Ganoderma lucidum Lingzi mushroom. The results also revealed the radio-protective effects of DLT to UV radiation. By adding 2% DLT to its culturing suspension, the growth of E. coli was significantly decreased, whereas a low DLT amount of about 0.5% slightly improved its growth, indicated that the DLT extract can be used as a promising protective substance against UV radiation. At the molecular level, the radio-protective effects of DLT were observed for both UV treated DNA and protein. Thus, DLT can protect DNA in vivo, but not in vitro. This effect was also observed for Taq polymerase, suggested that the radioprotection effect of DLT may due to it accelerated the degradation of radicals or species that produced in the suspensions during UV exposure. (author)

  5. Molecular processes as basis for plasmid-mediated bacterial UV-light resistance and mutagenesis

    International Nuclear Information System (INIS)

    Aleshkin, G.I.; Brukhanskij, G.V.; Skavronskaya, A.G.

    1985-01-01

    The increase of UV-resistance and UV-induced mutagenesis by lambda 1 pint intmid as well as molecular-genetic mechanisms of plasmid participation in reparation and DNA replication and its degradation after UV-irradiation in plasmid cells on pKM101 plasmid model have been investigated. Data testifying to the necessity of intmid integration in chromosome as obligatory stage of intmid participation in increasing UV-resistance of bacterial cells are obtained. It has been found that intmid raises UV-resistance of cells and increases respectively the UV-induced reverants efficiency. On the basis of the experiment data the conclusion is drawn that the intmid capacity to raise UV-resistance and, possibly, mutagenesis is bound not only with its integration into chromosome but also with pol A + chromosome replication by dependendent imtmid replication complex. It is shown that pKM101 plasmid ensures functioning in E coli cells of inducible, chloroamphenicol-resistant DNA replication, highly resistant to UV-light harmful effect and that the volume of excision reparation in E. coli cells carrying pKM101 plasmid is increased as compared with the volume of reparation in plasmid legs cells. The combination of the data obtained gives grounds to the authors to assume that inducible replication, inducible reparation of DNA and inducible decrease of DNA degradation determined by pKM101 plasmid may serve as recA + lexA + basis dependent increase of UV-resistance and mutagenesis and that these processes provide the possibility of functioning of integrative replication mechanism of plasmid participation in ensuring UV-resistance and mutagenesis of plants

  6. Physiological limit of the daily endogenous cholecalciferol synthesis from UV light in cattle

    DEFF Research Database (Denmark)

    Hymøller, L.; Jensen, S. K.; Kaas, P.

    2017-01-01

    The link between UV light (sunlight) and endogenous cholecalciferol (vitamin D3) synthesis in the skin of humans has been known for more than a 100 years, since doctors for the first time successfully used UV light to cure rickets in children. Years later, it was shown that UV light also had...

  7. 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

  8. 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

  9. Plasmid-associated sensitivity of Bacillus thuringiensis to UV light

    International Nuclear Information System (INIS)

    Benoit, T.G.; Wilson, G.R.; Bull, D.L.; Aronson, A.I.

    1990-01-01

    Spores and vegetative cells of Bacillus thuringiensis were more sensitive to UV light than were spores or cells of plasmid-cured B. thuringiensis strains or of the closely related Bacillus cereus. Introduction of B. thuringiensis plasmids into B. cereus by cell mating increased the UV sensitivity of the cells and spores. Protoxins encoded by one or more B. thuringiensis plasmids were not involved in spore sensitivity, since a B. thuringiensis strain conditional for protoxin accumulation was equally sensitive at the permissive and nonpermissive temperatures. In addition, introduction of either a cloned protoxin gene, the cloning vector, or another plasmid not containing a protoxin gene into a plasmid-cured strain of B. thuringiensis all increased the UV sensitivity of the spores. Although the variety of small, acid-soluble proteins was the same in the spores of all strains examined, the quantity of dipicolinic acid was about twice as high in the plasmid-containing strains, and this may account for the differences in UV sensitivity of the spores. The cells of some strains harboring only B. thuringiensis plasmids were much more sensitive than cells of any of the other strains, and the differences were much greater than observed with spores

  10. Assessing the use of Low Voltage UV-light Emitting Miniature LEDs for Marine Biofouling Control

    Science.gov (United States)

    2016-07-01

    of that required to drive traditional UV mercury lamps . Secondly, given their small size and relatively low cost, UV LEDs provide ease of maintenance...UNCLASSIFIED UNCLASSIFIED Assessing the use of Low Voltage UV -light Emitting Miniature LEDs for Marine Biofouling Control Richard...settling organisms. The introduction of miniature UV light emitting diodes ( LEDs ) as a light source enables them to be embedded into thin, flexible

  11. Plant responses to UV and blue light: biochemical and genetic approaches

    International Nuclear Information System (INIS)

    Jenkins, G.I.; Christie, J.M.; Fuglevand, G.; Long, J.C.; Jackson, J.A.

    1995-01-01

    UV and blue light control many aspects of plant growth and development. It is evident that several different photoreceptors mediate responses to UV and blue light, and there are reports of the functional and biochemical characterisation of a putative photoreceptor for phototropism and of the functional and molecular characterisation of the CRY1 photoreceptor, encoded by the Arabidopsis HY4 gene. The CRY1 photoreceptor mediates extension growth and gene expression responses to UV-A/blue light presumably through different or branching signal transduction pathways. Progress has been made in cell physiological and biochemical studies of UV/blue light signal transduction, but much remains to be done to relate candidate UV/blue signal transduction events to particular photoreceptors and responses. The application of a genetic approach in Arabidopsis has been responsible for many advances in understanding UV/blue responses, but further UV-B, UV-A and blue light response mutants need to be isolated. (author)

  12. Decreased survival of the λ15 bacteriophage induced by UV-365 nanometers in Escherichia coli

    International Nuclear Information System (INIS)

    Luca, M.E.M. de.

    1989-01-01

    The results of our investigation showed a new effect (not yet described in the current literature) of the UV-365 nm, verified when the bacteria E. coli was irradiated with this wavelenght and then infected with bacteriophage irradiated with short UV (254 nm). In these conditions we observed a decrease in the phage survival. This phenomenon was called Decreased Survival of the Bacteriophage (DSB). We were able to show that DSB was only induced in bacteria irradiated with UV-365 nm, proficient in recombination repair and owning 4-thiouridine in their tRNA. For the induction of DSB it is necessary to promote damage in the bacteriophage through UVA and UVB. It seems that DSB and SOS are antagonistic since DSB is able to suppress the mutation induced by SOS. (author)

  13. Practical considerations in the use of UV light for drinking water disinfection

    International Nuclear Information System (INIS)

    Jeyanayagam, S.; Cotton, C.

    2002-01-01

    Ultraviolet (UV) light was discovered approximately 150 years ago. The first commercial UV lamp was made in the early 1900s soon followed by the manufacture of the quartz sleeve. These technological advances allowed the first application of UV light for water disinfection in 1907 in France. In the mid 1980s, UV disinfection was named as a Best available technology (BAT) for wastewater disinfection in the United States. Fueled by the recent findings that UV disinfection can inactivate key pathogens at cost effective UV doses, the drinking water industry in North America is closely investigating its application in large installations. (author)

  14. Fish freshness estimation using eye image processing under white and UV lightings

    Science.gov (United States)

    Kanamori, Katsuhiro; Shirataki, Yuri; Liao, Qiuhong; Ogawa, Yuichi; Suzuki, Tetsuhito; Kondo, Naoshi

    2017-05-01

    A non-destructive method of estimating the freshness of fish is required for appropriate price setting and food safety. In particular, for determining the possibility of eating raw fish (sashimi), freshness estimation is critical. We studied such an estimation method by capturing images of fish eyes and performing image processing using the temporal changes of the luminance of pupil and iris. To detect subtle non-visible changes of these features, we used UV (375 nm) light illumination in addition to visible white light illumination. Polarization and two-channel LED techniques were used to remove strong specular reflection from the cornea of the eye and from clear-plastic wrap used to cover the fish to maintain humidity. Pupil and iris regions were automatically detected separately by image processing after the specular reflection removal process, and two types of eye contrast were defined as the ratio of mean and median pixel values of each region. Experiments using 16 Japanese dace (Tribolodon hakonensis) at 23° and 85% humidity for 24 hours were performed. The eye contrast of raw fish increase non-linearly in the initial period and then decreased; however, that of frozen-thawed fish decreased linearly throughout 24 hours, regardless of the lighting. Interestingly, the eye contrast using UV light showed a higher correlation with time than that using white light only in the case of raw fish within the early 6- hour period postmortem. These results show the possibility of estimating fish freshness in the initial stage when fish are eaten raw using white and UV lightings.

  15. Synthesis of polyaniline nanotubes through UV light catalytic method

    Directory of Open Access Journals (Sweden)

    Chuanyu Sun

    2015-03-01

    Full Text Available In this study, nitrocellulose (NC fiber blanket prepared by electrostatic spinning method has been used as a template, and copper nitrate (Cu(NO32 as an oxidant to synthesise polyaniline nanotubes doped with heteropolyacid (H4SiW12O40, SiW12 using UV light catalytic method. Infrared spectroscopy (IR, X-ray powder diffraction (XRD, scanning electron microscopy (SEM and transmission electron microscopy (TEM technologies were applied to characterize the prepared samples of polyaniline nanotubes. The results show that the external diameter of the tube is about 200 nm, and the internal diameter about 170 nm. We also give a reasonable speculation and explanation about the formation mechanism of the nanotubes.

  16. Decontamination System Utilizing Hydrogen Peroxide, UV Light and Catalytic Surfaces

    Science.gov (United States)

    1992-02-01

    Min %DMO RecoveredDisk# Catalyst (relative to control) 1 Ag 2 0 5.4 2 Ag2 0 10.1 4 FeTiO3 56 5 FeTio3 48 7 None 558 None 56 Control None 100 Ag 2 0...Std. Ag2 0 44 FeTiO3 Std. FeTiO3 100 Reference 87 - 36 - Table 9g. Experiment U, 1-09-91, 50% H2 02 , No UV Light, Run Time - 40 Min % DMO...Ag 2 0 2 7.8 44 1-09 T FeTiO3 2 52 100 1-09 U MnO 2 59 921-09 U Mn304 2 62 89 1-21 Y Ag 2 S/CaCO3 2 36 103 1-21 Y Ag 2 S 2 39 100 1-21 Z FeS2 2 6.0

  17. Photomorphogenetic responses to UV radiation and short-term red light in lettuce seedlings

    International Nuclear Information System (INIS)

    Kobzar, E.F.; Kreslavski, V.D.; Muzafarov, E.N.

    1998-01-01

    Effects of red light (R), far-red light (FR) and UV radiation on growth and greening of lettuce seedlings (Latuca sativa L., cv. Berlinskii) have been investigated. UV-B and UV-C inhibited hypocotyl elongation and stimulated cotyledonary growth. R in combination with UV-B and UV-C partly eliminated these effects, but FR increased those and reversed the R effect. Chlorophyll accumulation was inhibited by UV-B and UV-C. In comparison with cotyledonary growth, R strengthened the UV inhibitory effect, and FR reversed this effect of R. Thus, UV and phytochrome system modify the effects of each other on hypocotyl and leaf growth in lettuce seedlings depending on the level of active phytochrome formed

  18. UV Blocking Glass: Low Cost Filters for Visible Light Photocatalytic Assessment

    OpenAIRE

    Dunnill, Charles W.

    2014-01-01

    A number of commercially available art protection products have been compared and assessed for their suitability as UV blocking filters in the application of “visible light” photocatalytic research. Many groups claiming visible light photocatalytic success employ filters to block out stray UV radiation in order to justify that their photocatalysts are indeed visible light photocatalysts and not UV light photocatalysts. These filters come in varying degrees of ability and price and many author...

  19. Tolerance of the eriophyid mite Aceria salsolae to UV-A light and implications for biological control of Russian thistle.

    Science.gov (United States)

    Moran, Patrick J; Wibawa, M Irene; Smith, Lincoln

    2017-12-01

    Aceria salsolae (Acari: Eriophyidae) is being evaluated as a candidate biological control agent of Russian thistle (Salsola tragus, Chenopodiaceae), a major invasive weed of rangelands and dryland crops in the western USA. Prior laboratory host range testing under artificial lighting indicated reproduction on non-native Bassia hyssopifolia and on a native plant, Suaeda calceoliformis. However, in field tests in the native range, mite populations released on these 'nontarget' plants remained low. We hypothesized that UV-A light, which can affect behavior of tetranychid mites, would affect populations of the eriophyid A. salsolae differently on the target and nontarget plant species, decreasing the mite's realized host range. Plants were infested with A. salsolae under lamps that emitted UV-A, along with broad-spectrum lighting, and the size of mite populations and plant growth was compared to infested plants exposed only to broad-spectrum light. Russian thistle supported 3- to 55-fold larger mite populations than nontarget plants regardless of UV-A treatment. UV-A exposure did not affect mite populations on Russian thistle or S. calceoliformis, whereas it increased populations 7-fold on B. hyssopifolia. Main stems on nontarget plants grew 2- to 6-fold faster than did Russian thistle under either light treatment. The two nontarget plants attained greater volume under the control light regime than UV-A, but Russian thistle was unaffected. Although Russian thistle was always the superior host, addition of UV-A light to the artificial lighting regime did not reduce the ability of A. salsolae to reproduce on the two nontarget species, suggesting that UV-B or other environmental factors may be more important in limiting mite populations in the field.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  1. 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...

  2. The response of bean plants to UV-B radiation under different irradiances of background visible light

    International Nuclear Information System (INIS)

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

    1990-01-01

    Plants of Phaseolus vulgaris L. (cv. Stella) were grown in controlled conditions under three different irradiances of visible light with or without UV-B (280–320nm) radiation. The biologically effective UV-B radiation (UV-BBE) was 6.17 kJ m −2 d −1 , and simulated a c. 5% decrease in stratospheric ozone at 55.7°N, 13.4°E. The photon flux densities of the photosynthetically active radiation (PAR, 400–700 nm) were either 700 μmol m −2−1 (HL), 500, μmol m −2 s −1 (ML) or 230 μmol m −2 s −1 PAR (LL). Under high light (HL) conditions plus UV-B radiation, bean plants appeared most resistant to the enhanced levels of UV-B radiation, and responded only by increasing leaf thickness by c. 18%. A small increase in UV screening pigments was also observed. Both the lower irradiances (ML and LL) increased the sensitivity of the plants to UV-B radiation. Changes in leaf structure were also observed. Photosystem II was inhibited under ML and LL together with UV-B radiation, as determined by Chi fluorescence induction and calculation of the fluorescence half-rise times. Leaf reflectivity measurements showed that the amount of PAR able to penetrate leaves of UV-B treated plants was reduced, and that a possible correlation may exist between the reduced PAR levels, loss of Chi and lowered photosynthetic activity, especially for LL +UV-B grown plants, where surface reflection from leaves was highest. Changes in leaf chlorophyll content were mostly confined to plants grown under LL + UV-B, where a decrease of c. 20% was found. With regard to protective pigments (the carotenoids and UV screening pigments) plants subjected to different visible light conditions responded differently. Among the growth parameters measured, there was a substantial decrease in leaf area, particularly under LL + UV-B (c. 47% relative to controls), where leaf dry weight was also reduced by c. 25%. (author)

  3. Thermoluminescent properties of ZrO2:Mn for UV light dosimetry

    International Nuclear Information System (INIS)

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

    1999-01-01

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

  4. The EGFR family of receptors sensitizes cancer cells towards UV light

    DEFF Research Database (Denmark)

    Petersen, Steffen B.; Neves Petersen, Teresa; Olsen, Birgitte

    2008-01-01

    A combination of bioinformatics, biophysical, advanced laser studies and cell biology lead to the realization that laser-pulsed UV light stops cancer growth and induces apoptosis. We have previously shown that laser-pulsed UV (LP-UV) illumination of two different skin-derived cancer cell lines both...... bridges. The EGF receptor is often overexpressed in cancers and other proliferative skin disorders, it might be possible to significantly reduce the proliferative potential of these cells making them good targets for laser-pulsed UV-light treatment. The discovery that UV light can be used to open...... disulphide bridges in proteins upon illumination of nearby aromatic amino acids was the first step that lead to the hypothesis that UV light could modulate the structure and therefore the function of these key receptor proteins. The observation that membrane receptors (EGFR) contained exactly the motifs...

  5. Luminescence- and nanoparticle-mediated increase of light absorption by photoreceptor cells: Converting UV light to visible light.

    Science.gov (United States)

    Li, Lei; Sahi, Sunil K; Peng, Mingying; Lee, Eric B; Ma, Lun; Wojtowicz, Jennifer L; Malin, John H; Chen, Wei

    2016-02-10

    We developed new optic devices - singly-doped luminescence glasses and nanoparticle-coated lenses that convert UV light to visible light - for improvement of visual system functions. Tb(3+) or Eu(3+) singly-doped borate glasses or CdS-quantum dot (CdS-QD) coated lenses efficiently convert UV light to 542 nm or 613 nm wavelength narrow-band green or red light, or wide-spectrum white light, and thereby provide extra visible light to the eye. In zebrafish (wild-type larvae and adult control animals, retinal degeneration mutants, and light-induced photoreceptor cell degeneration models), the use of Tb(3+) or Eu(3+) doped luminescence glass or CdS-QD coated glass lenses provide additional visible light to the rod and cone photoreceptor cells, and thereby improve the visual system functions. The data provide proof-of-concept for the future development of optic devices for improvement of visual system functions in patients who suffer from photoreceptor cell degeneration or related retinal diseases.

  6. Intimate Coupling of Photocatalysis and Biodegradation for Degrading Phenol Using Different Light Types: Visible Light vs UV Light.

    Science.gov (United States)

    Zhou, Dandan; Xu, Zhengxue; Dong, Shanshan; Huo, Mingxin; Dong, Shuangshi; Tian, Xiadi; Cui, Bin; Xiong, Houfeng; Li, Tingting; Ma, Dongmei

    2015-07-07

    Intimate coupling of photocatalysis and biodegradation (ICPB) technology is attractive for phenolic wastewater treatment, but has only been investigated using UV light (called UPCB). We examined the intimate coupling of visible-light-induced photocatalysis and biodegradation (VPCB) for the first time. Our catalyst was prepared doping both of Er(3+) and YAlO3 into TiO2 which were supported on macroporous carriers. The macroporous carriers was used to support for the biofilms as well. 99.8% removal efficiency of phenol was achieved in the VPCB, and this was 32.6% higher than that in the UPCB. Mineralization capability of UPCB was even worse, due to less adsorbable intermediates and cell lysis induced soluble microbial products release. The lower phenol degradation in the UPCB was due to the serious detachment of the biofilms, and then the microbes responsible for phenol degradation were insufficient due to disinfection by UV irradiation. In contrast, microbial communities in the carriers were well protected under visible light irradiation and extracellular polymeric substances secretion was enhanced. Thus, we found that the photocatalytic reaction and biodegradation were intimately coupled in the VPCB, resulting in 64.0% removal of dissolved organic carbon. Therefore, we found visible light has some advantages over UV light in the ICPB technology.

  7. Comparison of UV-C and Pulsed UV Light Treatments for Reduction of Salmonella, Listeria monocytogenes, and Enterohemorrhagic Escherichia coli on Eggs.

    Science.gov (United States)

    Holck, Askild L; Liland, Kristian H; Drømtorp, Signe M; Carlehög, Mats; McLEOD, Anette

    2018-01-01

    Ten percent of all strong-evidence foodborne outbreaks in the European Union are caused by Salmonella related to eggs and egg products. UV light may be used to decontaminate egg surfaces and reduce the risk of human salmonellosis infections. The efficiency of continuous UV-C (254 nm) and pulsed UV light for reducing the viability of Salmonella Enteritidis, Listeria monocytogenes, and enterohemorrhagic Escherichia coli on eggs was thoroughly compared. Bacterial cells were exposed to UV-C light at fluences from 0.05 to 3.0 J/cm 2 (10 mW/cm 2 , for 5 to 300 s) and pulsed UV light at fluences from 1.25 to 18.0 J/cm 2 , resulting in reductions ranging from 1.6 to 3.8 log, depending on conditions used. Using UV-C light, it was possible to achieve higher reductions at lower fluences compared with pulsed UV light. When Salmonella was stacked on a small area or shielded in feces, the pulsed UV light seemed to have a higher penetration capacity and gave higher bacterial reductions. Microscopy imaging and attempts to contaminate the interior of the eggs with Salmonella through the eggshell demonstrated that the integrity of the eggshell was maintained after UV light treatments. Only minor sensory changes were reported by panelists when the highest UV doses were used. UV-C and pulsed UV light treatments appear to be useful decontamination technologies that can be implemented in continuous processing.

  8. Is the photoactive yellow protein a UV-B/blue light photoreceptor?

    NARCIS (Netherlands)

    Carroll, E. C.; Hospes, M.; Valladares, C.; Hellingwerf, K.J.; Larsen, D.S.

    2011-01-01

    UV light below 300 nm is shown to generate the first photocycle intermediate in the blue light photoreceptor Photoactive Yellow Protein. Fluorescence and ultrafast transient absorption measurements indicate two excitation pathways: UV-B absorption by the chromophore and Fluorescence Resonant Energy

  9. 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.

  10. Improved photoluminescence efficiency in UV nanopillar light emitting diode structures by recovery of dry etching damage.

    Science.gov (United States)

    Jeon, Dae-Woo; Jang, Lee-Woon; Jeon, Ju-Won; Park, Jae-Woo; Song, Young Ho; Jeon, Seong-Ran; Ju, Jin-Woo; Baek, Jong Hyeob; Lee, In-Hwan

    2013-05-01

    In this study, we have fabricated 375-nm-wavelength InGaN/AlInGaN nanopillar light emitting diodes (LED) structures on c-plane sapphire. A uniform and highly vertical nanopillar structure was fabricated using self-organized Ni/SiO2 nano-size mask by dry etching method. To minimize the dry etching damage, the samples were subjected to high temperature annealing with subsequent chemical passivation in KOH solution. Prior to annealing and passivation the UV nanopillar LEDs showed the photoluminescence (PL) efficiency about 2.5 times higher than conventional UV LED structures which is attributed to better light extraction efficiency and possibly some improvement of internal quantum efficiency due to partially relieved strain. Annealing alone further increased the PL efficiency by about 4.5 times compared to the conventional UV LEDs, while KOH passivation led to the overall PL efficiency improvement by more than 7 times. Combined results of Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) suggest that annealing decreases the number of lattice defects and relieves the strain in the surface region of the nanopillars whereas KOH treatment removes the surface oxide from nanopillar surface.

  11. UV-light exposure of insulin: pharmaceutical implications upon covalent insulin dityrosine dimerization and disulphide bond photolysis.

    Directory of Open Access Journals (Sweden)

    Manuel Correia

    Full Text Available In this work we report the effects of continuous UV-light (276 nm, ~2.20 W.m(-2 excitation of human insulin on its absorption and fluorescence properties, structure and functionality. Continuous UV-excitation of the peptide hormone in solution leads to the progressive formation of tyrosine photo-product dityrosine, formed upon tyrosine radical cross-linkage. Absorbance, fluorescence emission and excitation data confirm dityrosine formation, leading to covalent insulin dimerization. Furthermore, UV-excitation of insulin induces disulphide bridge breakage. Near- and far-UV-CD spectroscopy shows that UV-excitation of insulin induces secondary and tertiary structure losses. In native insulin, the A and B chains are held together by two disulphide bridges. Disruption of either of these bonds is likely to affect insulin's structure. The UV-light induced structural changes impair its antibody binding capability and in vitro hormonal function. After 1.5 and 3.5 h of 276 nm excitation there is a 33.7% and 62.1% decrease in concentration of insulin recognized by guinea pig anti-insulin antibodies, respectively. Glucose uptake by human skeletal muscle cells decreases 61.7% when the cells are incubated with pre UV-illuminated insulin during 1.5 h. The observations presented in this work highlight the importance of protecting insulin and other drugs from UV-light exposure, which is of outmost relevance to the pharmaceutical industry. Several drug formulations containing insulin in hexameric, dimeric and monomeric forms can be exposed to natural and artificial UV-light during their production, packaging, storage or administration phases. We can estimate that direct long-term exposure of insulin to sunlight and common light sources for indoors lighting and UV-sterilization in industries can be sufficient to induce irreversible changes to human insulin structure. Routine fluorescence and absorption measurements in laboratory experiments may also induce changes

  12. UV-light exposure of insulin: pharmaceutical implications upon covalent insulin dityrosine dimerization and disulphide bond photolysis.

    Science.gov (United States)

    Correia, Manuel; Neves-Petersen, Maria Teresa; Jeppesen, Per Bendix; Gregersen, Søren; Petersen, Steffen B

    2012-01-01

    In this work we report the effects of continuous UV-light (276 nm, ~2.20 W.m(-2)) excitation of human insulin on its absorption and fluorescence properties, structure and functionality. Continuous UV-excitation of the peptide hormone in solution leads to the progressive formation of tyrosine photo-product dityrosine, formed upon tyrosine radical cross-linkage. Absorbance, fluorescence emission and excitation data confirm dityrosine formation, leading to covalent insulin dimerization. Furthermore, UV-excitation of insulin induces disulphide bridge breakage. Near- and far-UV-CD spectroscopy shows that UV-excitation of insulin induces secondary and tertiary structure losses. In native insulin, the A and B chains are held together by two disulphide bridges. Disruption of either of these bonds is likely to affect insulin's structure. The UV-light induced structural changes impair its antibody binding capability and in vitro hormonal function. After 1.5 and 3.5 h of 276 nm excitation there is a 33.7% and 62.1% decrease in concentration of insulin recognized by guinea pig anti-insulin antibodies, respectively. Glucose uptake by human skeletal muscle cells decreases 61.7% when the cells are incubated with pre UV-illuminated insulin during 1.5 h. The observations presented in this work highlight the importance of protecting insulin and other drugs from UV-light exposure, which is of outmost relevance to the pharmaceutical industry. Several drug formulations containing insulin in hexameric, dimeric and monomeric forms can be exposed to natural and artificial UV-light during their production, packaging, storage or administration phases. We can estimate that direct long-term exposure of insulin to sunlight and common light sources for indoors lighting and UV-sterilization in industries can be sufficient to induce irreversible changes to human insulin structure. Routine fluorescence and absorption measurements in laboratory experiments may also induce changes in protein

  13. Protocol for Determining Ultraviolet Light Emitting Diode (UV-LED) Fluence for Microbial Inactivation Studies.

    Science.gov (United States)

    Kheyrandish, Ataollah; Mohseni, Madjid; Taghipour, Fariborz

    2018-06-15

    Determining fluence is essential to derive the inactivation kinetics of microorganisms and to design ultraviolet (UV) reactors for water disinfection. UV light emitting diodes (UV-LEDs) are emerging UV sources with various advantages compared to conventional UV lamps. Unlike conventional mercury lamps, no standard method is available to determine the average fluence of the UV-LEDs, and conventional methods used to determine the fluence for UV mercury lamps are not applicable to UV-LEDs due to the relatively low power output, polychromatic wavelength, and specific radiation profile of UV-LEDs. In this study, a method was developed to determine the average fluence inside a water suspension in a UV-LED experimental setup. In this method, the average fluence was estimated by measuring the irradiance at a few points for a collimated and uniform radiation on a Petri dish surface. New correction parameters were defined and proposed, and several of the existing parameters for determining the fluence of the UV mercury lamp apparatus were revised to measure and quantify the collimation and uniformity of the radiation. To study the effect of polychromatic output and radiation profile of the UV-LEDs, two UV-LEDs with peak wavelengths of 262 and 275 nm and different radiation profiles were selected as the representatives of typical UV-LEDs applied to microbial inactivation. The proper setup configuration for microorganism inactivation studies was also determined based on the defined correction factors.

  14. Proposed mechanism of thermoluminescence induced by UV light in the natural CaF2

    International Nuclear Information System (INIS)

    Las, W.C.

    1976-01-01

    The TL response of blue fluorite samples was measured as a function of exposure to 250 nm and 365 nm light. The TL response is linear in the low intensity region, becomes sublinear and has a maximum, decreasing afterwards for higher exposure intensities.The filled deep trap concentration, corresponding to the residual peak, was varied by annealing at different temperatures. The TL response maximum is proportional to this concentration. By exposing the sample to different light intensities a simultaneous decrease of the residual peak and increase of the lower temperature peaks was observed. This behavior suggests a charge transfer process from deep traps to shallow ones. A mathematical model based on this mechanism was proposed by Okuno and Watanabe in order to explain the experimental results. Besides the TL response curves, further data were obtained throughout a cycle of successive exposures to UV light. This experiment showed that the TL peak height presents two distinct decays as a function of the number of successive exposures. The decay is proportional to the probability of releasing charge from deep traps. The model above, however, didn't explain the experimental results. Two modifications were made: one, taking into account the retrapping probability, and the other considering the residual peak as composed of two peaks. From this latter assumption, it was possible to fit simultaneously the TL response curves and the residual peak decays, for 250 nm and 365 nm. The successive exposure curves, however, couldn't be explained in this way. The continuous decrease of the probability of charge release from deep traps as a function of the UV light intensity suggested a continuous distribution of energy levels for the residual peak. This last model fitted all 250 nm experimental data, and the glow curves of the residual peak [pt

  15. Treatment of blood with a pathogen reduction technology using UV light and riboflavin inactivates Ebola virus in vitro

    Science.gov (United States)

    Cap, Andrew P.; Pidcoke, Heather F.; Keil, Shawn D.; Staples, Hilary M.; Anantpadma, Manu; Carrion, Ricardo; Davey, Robert A.; Frazer-Abel, Ashley; Taylor, Audra L.; Gonzales, Richard; Patterson, Jean L.; Goodrich, Raymond P.

    2018-01-01

    BACKGROUND Transfusion of plasma from recovered patients after Ebolavirus (EBOV) infection, typically called ‘convalescent plasma,’ is an effective treatment for active disease available in endemic areas, but carries the risk of introducing other pathogens, including other strains of EBOV. A pathogen reduction technology using ultraviolet light and riboflavin (UV + RB) is effective against multiple enveloped, negative-sense, single-stranded RNA viruses that are similar in structure to EBOV. We hypothesized that UV + RB is effective against EBOV in blood products without activating complement or reducing protective immunoglobulin titers that are important for the treatment of ebolavirus disease (EVD). STUDY DESIGN AND METHODS Four in vitro experiments were conducted to evaluate effects of UV + RB on green fluorescent protein EBOV (EBOV-GFP), wild-type EBOV in serum and whole blood, respectively, and on immunoglobulins and complement in plasma. Initial titers for Experiments 1–3 were: 4.21 log10 GFP units/mL, 4.96 log10 infectious units per mL, and 4.23 log10 plaque forming units per mL (PFU/mL). Conditions tested in the first three experiments included: 1. EBOV-GFP + UV + RB; 2. EBOV-GFP + RB only; 3 EBOV-GFP + UV only; 4. EBOV-GFP without RB or UV; 5. Virus-free control + UV only; and 6. Virus-free control without RB or UV. RESULTS UV + RB reduced EBOV titers to non-detectable levels in both non-human primate serum (≥ 2.8 to 3.2 log reduction) and human whole blood (≥ 3.0 log reduction) without decreasing protective antibody titers in human plasma. CONCLUSION Our in vitro results demonstrate that the UV + RB treatment efficiently reduces EBOV titers to below limits of detection in both serum and whole blood. In vivo testing to determine whether UV + RB can improve convalescent blood product safety is indicated. PMID:27001363

  16. Decreased uv mutagenesis in cdc8, a DNA replication mutant of Saccharomyces cerevisiae

    International Nuclear Information System (INIS)

    Prakash, L.; Hinkle, D.; Prakash, S.

    1978-01-01

    A DNA replication mutant of yeast, cdc8, was found to decrease uv-induced reversion of lys2-1, arg4-17, tryl and ural. This effect was observed with all three alleles of cdc8 tested. Survival curves obtained following uv irradiation in cdc8 rad double mutants show that cdc8 is epistatic to rad6, as well as to rad1; cdc8 rad51 double mutants seem to be more sensitive than the single mutants. Since uv-induced reversion in cdc8 rad1 and cdc8 rad51 double mutants is like that of the cdc8 single mutants, we conclude that CDC8 plays a direct role in error-prone repair. To test whether CDC8 codes for a DNA polymerase, we have purified both DNA polymerase I and DNA polymerase II from cdc8 and CDC+ cells. The purified DNA polymerases from cdc8 were no more heat labile than those from CDC+, suggesting that CDC8 is not a structural gene for either enzyme

  17. Penetration of UV-A, UV-B, blue, and red light into leaf tissues of pecan measured by a fiber optic microprobe system

    Science.gov (United States)

    Qi, Yadong; Bai, Shuju; Vogelmann, Thomas C.; Heisler, Gordon M.

    2003-11-01

    The depth of light penetration from the adaxial surfaces of the mature leaves of pecan (Carya illinoensis) was measured using a fiber optic microprobe system at four wavelengths: UV-B (310nm), UV-A (360 nm), blue light (430nm), and red light (680nm). The average thickness of the leaf adaxial epidermal layer was 15um and the total leaf thickness was 219um. The patterns of the light attenuation by the leaf tissues exhibited strong wavelength dependence. The leaf adaxial epidermal layer was chiefly responsible for absorbing the UV-A UV-B radiation. About 98% of 310 nm light was steeply attenuated within the first 5 um of the adaxial epidermis; thus, very little UV-B radiation was transmitted to the mesophyll tissues where contain photosynthetically sensitive sites. The adaxial epidermis also attenuated 96% of the UV-A radiation. In contrast, the blue and red light penetrated much deeper and was gradually attenutated by the leaves. The mesophyll tissues attenuated 17% of the blue light and 42% of the red light, which were available for photosynthesis use. Since the epidermal layer absorbed nearly all UV-B light, it acted as an effective filter screening out the harmful radiation and protecting photosynthetically sensitive tissues from the UV-B damage. Therefore, the epidermal function of the UV-B screening effectiveness can be regarded as one of the UV-B protection mechanisms in pecan.

  18. Encapsulation of ethylhexyl methoxycinnamate, a light-sensitive UV filter, in lipid nanoparticles.

    Science.gov (United States)

    Durand, L; Habran, N; Henschel, V; Amighi, K

    2010-01-01

    The aim of this study was to encapsulate ethylhexyl methoxycinnamate (EMC), a commonly used UVB filter, in a solid lipid matrix in order to obtain microparticles and then nanoparticles to reduce its photo-instability under UV light exposure. Glyceryl behenate, rice bran wax and ozokerite were investigated for encapsulating EMC. The suspensions of nanoparticles contained 70% encapsulated EMC (relative to the lipid mass). The absorbance level at 310 nm of suspensions containing nanoparticles was more than twice that of those containing microparticles. So, decreasing the size of particles improved the efficiency of light protection, regardless of the lipid material used. Moreover, free EMC presented a 30% loss of its efficiency after 2 h of irradiation, whereas the three NLC formulations showed a loss of absorbency between 10% and 21%. The in vitro cutaneous penetration test did not show a higher potential penetration for EMC contained in nanosuspensions compared to free EMC.

  19. Physiological limit of the daily endogenous cholecalciferol synthesis from UV light in cattle.

    Science.gov (United States)

    Hymøller, L; Jensen, S K; Kaas, P; Jakobsen, J

    2017-04-01

    The link between UV light (sunlight) and endogenous cholecalciferol (vitamin D 3 ) synthesis in the skin of humans has been known for more than a 100 years, since doctors for the first time successfully used UV light to cure rickets in children. Years later, it was shown that UV light also had a significant effect on the cholecalciferol status in the body of cattle. The cholecalciferol status in the body is measured as the plasma concentration of 25-hydroxycholecalciferol, which in cattle and humans is the major circulating metabolite of cholecalciferol. Very little is, however, known about the quantitative efficiency of UV light as a source of cholecalciferol in cattle nutrition and physiology. Hence, the aim of this study was to determine the efficiency of using UV light for increasing the plasma 25-hydroxycholecalciferol concentration in cholecalciferol-deprived cattle. Twelve cows deprived of cholecalciferol for 6 months were divided into three treatment groups and exposed to UV light for 30, 90 or 120 min/day during 28 days. UV-light wavelengths ranged from 280 to 415 nm and 30-min exposure to the UV light was equivalent to 60-min average summer-sunlight exposure at 56 °N. Blood samples were collected every 3-4 days and analysed for 25-hydroxycholecalciferol and cholecalciferol. Results showed that increasing the exposure time from 90-120 min/day did not change the slope of the daily increase in plasma 25-hydroxycholecalciferol. Hence, it appears that cholecalciferol-deprived dairy cattle are able to increase their plasma 25-hydroxycholecalciferol concentration by a maximum of 1 ng/ml/day from UV-light exposure. Journal of Animal Physiology and Animal Nutrition © 2016 Blackwell Verlag GmbH.

  20. Characterization and optimization of an inkjet-printed smart textile UV-sensor cured with UV-LED light

    Science.gov (United States)

    Seipel, S.; Yu, J.; Periyasamy, A. P.; Viková, M.; Vik, M.; Nierstrasz, V. A.

    2017-10-01

    For the development of niche products like smart textiles and other functional high-end products, resource-saving production processes are needed. Niche products only require small batches, which makes their production with traditional textile production techniques time-consuming and costly. To achieve a profitable production, as well as to further foster innovation, flexible and integrated production techniques are a requirement. Both digital inkjet printing and UV-light curing contribute to a flexible, resource-efficient, energy-saving and therewith economic production of smart textiles. In this article, a smart textile UV-sensor is printed using a piezoelectric drop-on-demand printhead and cured with a UV-LED lamp. The UVcurable ink system is based on free radical polymerization and the integrated UVsensing material is a photochromic dye, Reversacol Ruby Red. The combination of two photoactive compounds, for which UV-light is both the curer and the activator, challenges two processes: polymer crosslinking of the resin and color performance of the photochromic dye. Differential scanning calorimetry (DSC) is used to characterize the curing efficiency of the prints. Color measurements are made to determine the influence of degree of polymer crosslinking on the developed color intensities, as well as coloration and decoloration rates of the photochromic prints. Optimized functionality of the textile UV-sensor is found using different belt speeds and lamp intensities during the curing process.

  1. p38-MK2 signaling axis regulates RNA metabolism after UV-light-induced DNA damage

    DEFF Research Database (Denmark)

    Borisova, Marina E; Voigt, Andrea; Tollenaere, Maxim A X

    2018-01-01

    quantitative phosphoproteomics and protein kinase inhibition to provide a systems view on protein phosphorylation patterns induced by UV light and uncover the dependencies of phosphorylation events on the canonical DNA damage signaling by ATM/ATR and the p38 MAP kinase pathway. We identify RNA-binding proteins......Ultraviolet (UV) light radiation induces the formation of bulky photoproducts in the DNA that globally affect transcription and splicing. However, the signaling pathways and mechanisms that link UV-light-induced DNA damage to changes in RNA metabolism remain poorly understood. Here we employ...

  2. Quantum dots/silica/polymer nanocomposite films with high visible light transmission and UV shielding properties.

    Science.gov (United States)

    Mumin, Md Abdul; Xu, William Z; Charpentier, Paul A

    2015-08-07

    The dispersion of light-absorbing inorganic nanomaterials in transparent plastics such as poly(ethylene-co-vinyl acetate) (PEVA) is of enormous current interest in emerging solar materials, including photovoltaic (PV) modules and commercial greenhouse films. Nanocrystalline semiconductor or quantum dots (QDs) have the potential to absorb UV light and selectively emit visible light, which can control plant growth in greenhouses or enhance PV panel efficiencies. This work provides a new and simple approach for loading mesoporous silica-encapsulated QDs into PEVA. Highly luminescent CdS and CdS-ZnS core-shell QDs with 5 nm size were synthesized using a modified facile approach based on pyrolysis of the single-molecule precursors and capping the CdS QDs with a thin layer of ZnS. To make both the bare and core-shell structure QDs more resistant against photochemical reactions, a mesoporous silica layer was grown on the QDs through a reverse microemulsion technique based on hydrophobic interactions. By careful experimental tuning, this encapsulation technique enhanced the quantum yield (∼65%) and photostability compared to the bare QDs. Both the encapsulated bare and core-shell QDs were then melt-mixed with EVA pellets using a mini twin-screw extruder and pressed into thin films with controlled thickness. The results demonstrated for the first time that mesoporous silica not only enhanced the quantum yield and photostability of the QDs but also improved the compatibility and dispersibility of QDs throughout the PEVA films. The novel light selective films show high visible light transmission (∼90%) and decreased UV transmission (∼75%).

  3. Ambient UV-B radiation decreases photosynthesis in high arctic Vaccinium uliginosum.

    OpenAIRE

    Albert, Kristian; Ro-Poulsen, Helge; N. Mikkelsen, Teis

    2008-01-01

    UV-B-exclusion experiment was established in high arctic Zackenberg, Northeast Greenland, to investigate the possible effects of ambient UV-B on plant performance. During almost a whole growing season, canopy gas exchange and Chl fluorescence were measured on Vaccinium uliginosum (bog blueberry). Leaf area, biomass, carbon, nitrogen and UV-B-absorbing compounds were determined from a late season harvest. Compared with the reduced UV-B treatment, the plants in ambient UV-B were found to have a...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-10-15

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

  5. Footprints of the Sun: Memory of UV and Light Stress in Plants

    Directory of Open Access Journals (Sweden)

    Ralf eMüller-Xing

    2014-09-01

    Full Text Available Sunlight provides the necessary energy for plant growth via photosynthesis but high light and particular its integral ultraviolet (UV part causes stress potentially leading to serious damage to DNA, proteins and other cellular components. Plants show adaptation to environmental stresses, sometimes referred to as plant memory. There is growing evidence that plants memorize exposure to biotic or abiotic stresses by epigenetic mechanisms at the cellular level. UV target genes such as CHALCONE SYNTHASE (CHS response immediately to UV treatment and studies of the recently identified UV-B receptor UV RESISTANCE LOCUS 8 (UVR8 confirm the expedite nature of UV signalling. Considering these findings, an UV memory seems redundant. However, several lines of evidence suggest that plants may develop an epigenetic memory of UV and light stress, but in comparison to other abiotic stresses there has been relatively little investigation. Here we summarize the state of knowledge about acclimation and adaptation of plants to UV light and discuss the possibility of chromatin based epigenetic memory.

  6. UV light-induced cyclobutane pyrimidine dimers are mutagenic in mammalian cells

    International Nuclear Information System (INIS)

    Protic-Sabljic, M.; Tuteja, N.; Munson, P.J.; Hauser, J.; Kraemer, K.H.; Dixon, K.

    1986-01-01

    We used a simian virus 40-based shuttle vector plasmid, pZ189, to determine the role of pyrimidine cyclobutane dimers in UV light-induced mutagenesis in monkey cells. The vector DNA was UV irradiated and then introduced into monkey cells by transfection. After replication, vector DNA was recovered from the cells and tested for mutations in its supF suppressor tRNA marker gene by transformation of Escherichia coli carrying a nonsense mutation in the beta-galactosidase gene. When the irradiated vector was treated with E. coli photolyase prior to transfection, pyrimidine cyclobutane dimers were removed selectively. Removal of approximately 90% of the pyrimidine cyclobutane dimers increased the biological activity of the vector by 75% and reduced its mutation frequency by 80%. Sequence analysis of 72 mutants recovered indicated that there were significantly fewer tandem double-base changes and G X C----A X T transitions (particularly at CC sites) after photoreactivation of the DNA. UV-induced photoproducts remained (although at greatly reduced levels) at all pyr-pyr sites after photoreactivation, but there was a relative increase in photoproducts at CC and TC sites and a relative decrease at TT and CT sites, presumably due to a persistence of (6-4) photoproducts at some CC and TC sites. These observations are consistent with the fact that mutations were found after photoreactivation at many sites at which only cyclobutane dimers would be expected to occur. From these results we conclude that UV-induced pyrimidine cyclobutane dimers are mutagenic in DNA replicated in monkey cells

  7. The effect of UV-light on DNA metabolism of lymphocytes during radiotherapy

    International Nuclear Information System (INIS)

    Klein, W.; Altmann, H.; Klein, H.; Alth, G.; Koren, H.

    1980-02-01

    The effects of gamma plus electron therapy and only gammatherapy, respectively, were investigated in lymphocytes of the peripheral blood of 10 patients with malignancies. The efficiency of DNA repair was tested by an irradiation of the cells with UV light beside radiotherapy. Using only gamma rays for therapy, the effects by UV light were not so pronounced than for using gamma plus electron therapy. (author)

  8. Photocatalytic Properties of g-C₃N₄-TiO₂ Heterojunctions under UV and Visible Light Conditions.

    Science.gov (United States)

    Fagan, Rachel; McCormack, Declan E; Hinder, Steven J; Pillai, Suresh C

    2016-04-14

    Graphitic carbon nitride ( g -C₃N₄) and titanium dioxide (TiO₂) were chosen as a model system to investigate photocatalytic abilities of heterojunction system under UV and visible light conditions. The use of g -C₃N₄ has been shown to be effective in the reduction in recombination through the interaction between the two interfaces of TiO₂ and g -C₃N₄. A simple method of preparing g -C₃N₄ through the pyrolysis of melamine was employed, which was then added to undoped TiO₂ material to form the g -C₃N₄-TiO₂ system. These materials were then fully characterized by X-ray diffraction (XRD), Brunauer Emmett Teller (BET), and various spectroscopic techniques including Raman, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), diffuse absorbance, and photoluminescence analysis. Photocatalysis studies were conducted using the model dye, rhodamine 6G utilizing visible and UV light irradiation. Raman spectroscopy confirmed that a composite of the materials was formed as opposed to a mixture of the two. Using XPS analysis, a shift in the nitrogen peak to that indicative of substitutional nitrogen was detected for all doped samples. This is then mirrored in the diffuse absorbance results, which show a clear decrease in band gap values for these samples, showing the effective band gap alteration achieved through this preparation process. When g -C₃N₄-TiO₂ samples were analyzed under visible light irradiation, no significant improvement was observed compared that of pure TiO₂. However, under UV light irradiation conditions, the photocatalytic ability of the doped samples exhibited an increased reactivity when compared to the undoped TiO₂ (0.130 min -1 ), with 4% g -C₃N₄-TiO₂ (0.187 min -1 ), showing a 43.9% increase in reactivity. Further doping to 8% g -C₃N₄-TiO₂ lead to a decrease in reactivity against rhodamine 6G. BET analysis determined that the surface area of the 4% and 8% g -C

  9. Evidence for some signal transduction elements involved in UV-light-dependent responses in parsley protoplasts

    International Nuclear Information System (INIS)

    Frohnmeyer, H.; Bowler, C.; Schäfer, E.

    1997-01-01

    The signalling pathways used by UV-light are largely unknown. Using protoplasts from a heterotrophic parsley (Petroselinum crispum L.) cell culture that exclusively respond to UV-B light between 300 and 350 nm with a fast induction of genes encoding flavonoid biosynthetic enzymes, information was obtained about the UV-light signal transduction pathway for chalcone synthase (CHS) and phenylalanine ammonia-lyase (PAL) gene expression. Pharmacological effectors which influence intracellular calcium levels, calmodulin and the activity of serine/threonine kinases also changed the UV-light-dependent expression of these genes. This evaluation indicated the participation of these components on the UV-B-mediated signal transduction cascade to CHS. In contrast, neither membrane-permeable cyclic GMP nor the tyrosine kinase inhibitor genistein affected CHS or PAL expression. Similar results were obtained in protoplasts, which have been transiently transformed with CHS-promoter/GUS (β-glucuronidase) reporter fusion constructs. The involvement of calcium and calmodulin was further indicated in a cell-free light-responsive in vitro transcription system from evacuolated parsley protoplasts. In conclusion, there is evidence now that components of the UV-light-dependent pathway leading to the CHS-promoter are different from the previously characterized cGMP-dependent pathway to CHS utilized by phytochrome in soybean (Glycine max) and tomato seedlings (Lycopersicon esculentum). (author)

  10. Preparation of pectin/silver nanoparticles composite films with UV-light barrier and properties.

    Science.gov (United States)

    Shankar, Shiv; Tanomrod, Nattareya; Rawdkuen, Saroat; Rhim, Jong-Whan

    2016-11-01

    Silver nanoparticles (AgNPs) was synthesized by a green method using an aqueous extract of Caesalpinia mimosoides Lamk (CMLE) as reducing and stabilizing agents, and they were used for the preparation of pectin-based antimicrobial composite films. The AgNPs were spherical in shape with the size in the range of 20-80nm and showed the absorption peak around 500nm. The pectin/AgNPs composite film exhibited characteristic absorption peak of AgNPs at 480nm. The surface color and light transmittance of the pectin films were greatly influenced by the addition of AgNPs. The lightness of the films decreased, however, redness and yellowness of the films increased after incorporation of AgNPs. UV-light barrier property of the pectin film increased significantly with a little decrease in the transparency. Though there were no structural changes in the pectin film by the incorporation of CMLE and AgNPs as indicated by the FTIR results, the film properties such as thermal stability, mechanical strength, and water vapor barrier properties of the pectin films increased. The pectin/AgNPs nanocomposite films exhibited strong antibacterial activity against food-borne pathogenic bacteria, Escherichia coli and Listeria monocytogenes. Copyright © 2016 Elsevier B.V. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-07-01

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

  12. Skin protection against UV light by dietary antioxidants.

    Science.gov (United States)

    Fernández-García, Elisabet

    2014-09-01

    There is considerable interest in the concept of additional endogenous photoprotection by dietary antioxidants. A number of efficient micronutrients are capable of contributing to the prevention of UV damage in humans. These compounds protect molecular targets by scavenging reactive oxygen species, including excited singlet oxygen and triplet state molecules, and also modulate stress-dependent signaling and/or suppress cellular and tissue responses like inflammation. Micronutrients present in the diet such as carotenoids, vitamins E and C, and polyphenols contribute to antioxidant defense and may also contribute to endogenous photoprotection. This review summarizes the literature concerning the use of dietary antioxidants as systemic photoprotective agents towards skin damage induced by UVA and UVB. Intervention studies in humans with carotenoid-rich diets have shown photoprotection. Interestingly, rather long treatment periods (a minimum of 10 weeks) were required to achieve this effect. Likewise, dietary carotenoids exert their protective antioxidant function in several in vitro and in vivo studies when present at sufficiently high concentration. A combination of vitamins E and C protects the skin against UV damage. It is suggested that daily consumption of dietary polyphenols may provide efficient protection against the harmful effects of solar UV radiation in humans. Furthermore, the use of these micronutrients in combination may provide an effective strategy for protecting human skin from damage by UV exposure.

  13. Photoinhibition and photosynthetic pigment reorganisation dynamics in light/darkness cycles as photoprotective mechanisms of Porphyra umbilicalis against damaging effects of UV radiation

    Directory of Open Access Journals (Sweden)

    José Aguilera

    2008-03-01

    Full Text Available Porphyra umbilicalis L. Kutzing collected from the upper intertidal zone at Helgoland, North Sea, was exposed to different spectral ranges of UV radiation under both 12/12 h light/dark cycles and continuous irradiation. In light/dark cycles, oscillations of the optimal quantum yield (Fv /Fm were observed during the experiments, reaching maximal values at the end of the light phase followed by lower values during the dark phase. Decreased Fv /Fm was observed in thalli illuminated with photosynthetic active radiation (PAR plus UV-A and PAR+UV-A+UV-B, compared with the PAR control, indicating a certain degree of UV-induced photoinhibition. In addition, a decrease in the percentage of change of the linear initial slope and maximum electron transport rate (ETR estimated from ETR vs. irradiance curves was induced by UV radiation during the light phase. Recovery during the 12 h dark phase was almost completed in UV-A treated plants. PAR+UV-A seemed not to affect the photosynthesis, measured as O2 production. However, a decrease in O2 production was observed in the PAR+UV-A+UV-B treatment, but it recovered to initial values after 48 h of culture. No changes in total content of photosynthetic pigments were observed. However, thallus absorptance and the in vivo absorption cross-section in the PAR range (400-700 nm normalised to Chl a (a* parameter fluctuated during light/dark cycles and were positively correlated with changes in the optimum quantum yield, thus indicating that daily pigment reorganisation in the light-harvesting complex may play a key role in the photosynthetic performance of the algae. Both UV-A and UV-B treatments under continuous irradiation induced a significant reduction in the optimal quantum yield, ETR efficiency and photosynthetic oxygen production during the first 36 h to values around 30% of the initial ones. Thus, different protective mechanisms against UV stress can be observed in P. umbilicalis: dynamic photoinhibition when

  14. The UV and Laser Aging for PMMA/BDK/Azo-dye Polymer Blend Cured by UV Light Beams

    International Nuclear Information System (INIS)

    Ahmad, A A; Omari, A M

    2015-01-01

    A polymeric-based solution blend composed of Azo-dye methyl red (MR) doped with polymethelmethacrelate (PMMA) solution, in addition, to the BenzylDimethylKetal (BDK) photoinitiator was made with optimum molar ratios and deposited on glass substrate by spin coating technique. The samples were then exposed to UV light beams in order to assist the layers polymerization by the proper exposure process. The photo chemical reaction occurred during the UV light polymerization process induces photo refractive changes which were presented as a function of wavelength or photon energy. Two main strong absorption peaks were observed in the films at around 330 nm (3.75 eV) and 500 nm (2.48 eV) for different curing time periods. This phenomenon enhances the films usage for optical data storage media at these two wavelengths. Since the deposited films were then useful as based layers for Read/Write optical data storage media, they were then tested by UV or laser Read/Write beams independently. The optical properties of the films were investigated while exposed to each beam. Finally, their optical properties were investigated as a function of aging time in order to relate the temporary and/or permanent light-exposure effect on the films compared to their optical properties before the light exposure. The films show a low absorbance at 630 nm (1.97 eV) and high absorbance at 480 nm (2.58 eV). This fact makes it possible to record holographic gratings in the polymeric film upon light exposure. In all cases the optical properties were evaluated by using the very sensitive, non destructive surface testing spectroscopic ellipsometry technique. The films were characterized in the spectral range of 300 to 1000 nm using Lorentz oscillator model with one oscillator centred at 4.15 eV. This study has been supported by the SEM and EDAX results to investigate the effect of the UV and visible beams on their optical properties. The results of this research determined the proper conditions for

  15. Enhancement of SV40 transformation by treatment of C3H2K cells with uv light and caffeine. I. Combined effect of uv light and caffeine

    International Nuclear Information System (INIS)

    Ide, T.; Anzai, K.; Andoh, T.

    1975-01-01

    Treatment of cultured mouse cells, C3H2K, with uv light and/or caffeine enhanced the frequency of SV40-induced transformation. This enhancement depends upon the doses of uv and caffeine and the mode of combination of these agents. Irradiation of cells with increasing doses of uv just before infection resulted in approximately 2-fold enhancement of the transformation frequency up to a dose of 90 ergs/mm 2 and 3.3-fold at 150 ergs/mm 2 . Addition of 1 mM caffeine to the medium for 4 days subsequent to infection brought about a 2-fold enhancement. When cells were irradiated and treated with 1 mM caffeine, the enhancement was approximately 4-fold up to a uv dose of 90 ergs/mm 2 and 5.9-fold at 150 ergs/mm 2 . When 0.1 to 4 mM caffeine was added for 4 days postinfection, the absolute number of transformations increased, and an enhancement ratio of 1.3 to 6.8 resulted. After the addition of the same increasing doses of caffeine to uv-irradiated cells (75 ergs/mm 2 ), the enhancement of transformation frequency was even higher ranging 2.0 to 13.3. The transformation frequencies thus obtained by the double treatment were always higher than those predicted if uv and caffeine acted additively. The transformation frequency was little affected by the addition of dibutyrylcyclic AMP and theophylline

  16. 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.

  17. Wastewater disinfection alternatives: chlorine, ozone, peracetic acid, and UV light.

    Science.gov (United States)

    Mezzanotte, V; Antonelli, M; Citterio, S; Nurizzo, C

    2007-11-01

    Disinfection tests were carried out at pilot scale to compare the disinfection efficiency of ozone, sodium hypochlorite (NaOCl), peracetic acid (PAA), and UV irradiation. Total coliforms, fecal coliforms, and Escherichia coli were monitored as reference microorganisms. Total heterotrophic bacteria (THB) were also enumerated by cytometry. At similar doses, NaOCl was more effective than PAA, and its action was less affected by contact time. The results obtained by ozonation were comparable for total coliforms, fecal coliforms, and E. coli. On the contrary, some differences among the three indicators were observed for NaOCl, PAA, and UV. Differences increased with increasing values of the disinfectant concentration times contact time (C x t) and were probably the result of different initial counts, as total coliforms include fecal coliforms, which include E. coli. The UV irradiation lead to complete E. coli removals, even at low doses (10 to 20 mJ/cm2). Total heterotrophic bacteria appeared to be too wide a group to be a good disinfection indicator; no correlation was found among THB inactivation, dose, and contact time.

  18. 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.

  19. 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.

  20. 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

  1. UV Blocking Glass: Low Cost Filters for Visible Light Photocatalytic Assessment

    Directory of Open Access Journals (Sweden)

    Charles W. Dunnill

    2014-01-01

    Full Text Available A number of commercially available art protection products have been compared and assessed for their suitability as UV blocking filters in the application of “visible light” photocatalytic research. Many groups claiming visible light photocatalytic success employ filters to block out stray UV radiation in order to justify that their photocatalysts are indeed visible light photocatalysts and not UV light photocatalysts. These filters come in varying degrees of ability and price and many authors fail to correctly characterise their filters in individual papers. The use of effective filters to prevent both false positive and false negative results is important to maintain scientific rigor and create accurate understanding of the subject. The optimum UV filter would have the highest UV blocking properties (<390 nm and simultaneously the highest visible light transmission (390–750 nm. Single and double layers of each of the glass products were assessed as well as laminate products. The conclusions show an inexpensive and highly effective setup for the conduction of visible light photochemistry that should be incorporated as a standard part in any researcher’s work where the claim of visible light activity is made.

  2. Disinfection of Spacecraft Potable Water Systems by Photocatalytic Oxidation Using UV-A Light Emitting Diodes

    Science.gov (United States)

    Birmele, Michele N.; O'Neal, Jeremy A.; Roberts, Michael S.

    2011-01-01

    Ultraviolet (UV) light has long been used in terrestrial water treatment systems for photodisinfection and the removal of organic compounds by several processes including photoadsorption, photolysis, and photocatalytic oxidation/reduction. Despite its effectiveness for water treatment, UV has not been explored for spacecraft applications because of concerns about the safety and reliability of mercury-containing UV lamps. However, recent advances in ultraviolet light emitting diodes (UV LEDs) have enabled the utilization of nanomaterials that possess the appropriate optical properties for the manufacture of LEDs capable of producing monochromatic light at germicidal wavelengths. This report describes the testing of a commercial-off-the-shelf, high power Nichia UV-A LED (250mW A365nnJ for the excitation of titanium dioxide as a point-of-use (POD) disinfection device in a potable water system. The combination of an immobilized, high surface area photocatalyst with a UV-A LED is promising for potable water system disinfection since toxic chemicals and resupply requirements are reduced. No additional consumables like chemical biocides, absorption columns, or filters are required to disinfect and/or remove potentially toxic disinfectants from the potable water prior to use. Experiments were conducted in a static test stand consisting of a polypropylene microtiter plate containing 3mm glass balls coated with titanium dioxide. Wells filled with water were exposed to ultraviolet light from an actively-cooled UV-A LED positioned above each well and inoculated with six individual challenge microorganisms recovered from the International Space Station (ISS): Burkholderia cepacia, Cupriavidus metallidurans, Methylobacterium fujisawaense, Pseudomonas aeruginosa, Sphingomonas paucimobilis and Wautersia basilensis. Exposure to the Nichia UV-A LED with photocatalytic oxidation resulted in a complete (>7-log) reduction of each challenge bacteria population in UV-A LEDs and semi

  3. Epidermal UV-A absorbance and whole-leaf flavonoid composition in pea respond more to solar blue light than to solar UV radiation.

    Science.gov (United States)

    Siipola, Sari M; Kotilainen, Titta; Sipari, Nina; Morales, Luis O; Lindfors, Anders V; Robson, T Matthew; Aphalo, Pedro J

    2015-05-01

    Plants synthesize phenolic compounds in response to certain environmental signals or stresses. One large group of phenolics, flavonoids, is considered particularly responsive to ultraviolet (UV) radiation. However, here we demonstrate that solar blue light stimulates flavonoid biosynthesis in the absence of UV-A and UV-B radiation. We grew pea plants (Pisum sativum cv. Meteor) outdoors, in Finland during the summer, under five types of filters differing in their spectral transmittance. These filters were used to (1) attenuate UV-B; (2) attenuate UV-B and UV-A radiation signals that extend into the visible region of the solar spectrum. Furthermore, solar blue light instead of solar UV-B radiation can be the main regulator of phenolic compound accumulation in plants that germinate and develop outdoors. © 2014 John Wiley & Sons Ltd.

  4. UV-vis light transmittance through tinted contact lenses and the effect of color on values.

    Science.gov (United States)

    Osuagwu, Uchechukwu L; Ogbuehi, Kelechi C

    2014-06-01

    To assess the transmittance, in the 200-700nm electromagnetic radiation spectrum, by popularly used tinted soft contact lenses (CLs). The spectra transmittances of ultraviolet (UV)-blocking (I Day Acuvue Define, Freshlook ONE DAY) and non-UV-blocking (Durasoft 3, Tutti, and NeoCosmo) tinted soft CLs were tested. The transmittance of each lens, including nine different colors of Freshlook CL was recorded on spectrophotometer, and the data used to also calculate a UV protection factor (PF) for each lens brand tested, with a higher value indicating a higher level of protection. The UV-blocking CLs significantly reduced UVC, UVB & UVA transmission and thereby meet the American National Standards Institution standard for class 2 UV blockers: a maximum of 30% transmittance of UVA and 5% transmittance of UVB wavelengths. In contrast, the Durasoft 3, Tutti, and NeoCosmo CLs demonstrated negligible UV-blockage. The Acuvue Define CL offered the greatest protection from UVC (PF=69) and UVB (PF=55), but with only 35% luminous transmittance, while the Freshlook CL (especially gemstone green) offered the best protection from UVA (PF=24) and showed about 55% translucency. Overall, the UV-blocking CLs performed equally well across the UV spectrum. Different colors of Freshlook CL transmitted statistically and clinically significantly different amounts of visible light but similar amounts of UVR. Freshlook and Acuvue Define CLs which are designated as UV-blockers significantly reduced UVR transmission to safe levels whereas Tutti, NeoCosmo and Durasoft 3 did not. Transmission within the Freshlook CL family was more dependent on color in the visible light spectrum, but not in the UV-spectrum, where the gemstone green performing best among the tested colors. Copyright © 2013 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  5. Photomorphogenic effects of UV-B radiation on plants: consequences for light competition

    International Nuclear Information System (INIS)

    Barnes, P.W.; Ballaré, C.L.; Caldwell, M.M.

    1996-01-01

    A combination of field and labotatory studies were conducted to explore the nature of photomorphogenic effects of ultraviolet-B radiation (UV-B; 280–320 nm) on plant morphology and to evaluate the ecological consequences of these alterations in morphology for interspecific competition. Under laboratory conditions, seedlings of cucumber (Cucumis sativus L.) and tomato (Lycopersicon esculentum Mill.) exhibited appreciable (ca. 50%) and rapid (< 3h) inhibition in hypocotyl elongation in response to UV-B exposure. In cucumber, this inhibition was reversible, occurred without any associated changes in dry matter production and was caused by UV-B incident on the cotyledons and not the stem or growing tip. Inhibition of stem elongation in etiolated tomato seedlings occurred at least 3 h prior to the onset of accumulation of UV-absorbing pigments and monochromatic UV supplied against a background of visible radiation revealed maximum effectiveness in inhibition around 300 nm. Collectively, these findings suggest that a specific, but yet unidentified, UV-B photoreceptor is involved in mediating certain morphological responses to UV-B. For mixtures of wheat (Triticum aestivum L.) and wild oat (Avena fatua L.), a common weedy competitor, supplemental UV-B irradiation in the field differentially altered shoot morphology which resulted in changes in canopy structure, light interception and calculated stand photosynthesis. It is argued that, because of its asymmetrical nature, competition for light can potentially amplify the effects of UV-B on shoot morphology and may, therefore, be an important mechanism by which changes in the solar UV-B spectrum associated with stratospheric ozone reduction could alter the composition and character of terrestrial vegetation

  6. The role of coccoliths in protecting Emiliania huxleyi against stressful light and UV radiation

    Science.gov (United States)

    Xu, Juntian; Bach, Lennart T.; Schulz, Kai G.; Zhao, Wenyan; Gao, Kunshan; Riebesell, Ulf

    2016-08-01

    Coccolithophores are a group of phytoplankton species which cover themselves with small scales (coccoliths) made of calcium carbonate (CaCO3). The reason why coccolithophores form these calcite platelets has been a matter of debate for decades but has remained elusive so far. One hypothesis is that they play a role in light or UV protection, especially in surface dwelling species like Emiliania huxleyi, which can tolerate exceptionally high levels of solar radiation. In this study, we tested this hypothesis by culturing a calcified and a naked strain under different light conditions with and without UV radiation. The coccoliths of E. huxleyi reduced the transmission of visible radiation (400-700 nm) by 7.5 %, that of UV-A (315-400 nm) by 14.1 % and that of UV-B (280-315 nm) by 18.4 %. Growth rates of the calcified strain (PML B92/11) were about 2 times higher than those of the naked strain (CCMP 2090) under indoor constant light levels in the absence of UV radiation. When exposed to outdoor conditions (fluctuating sunlight with UV radiation), growth rates of calcified cells were almost 3.5 times higher compared to naked cells. Furthermore, the relative electron transport rate was 114 % higher and non-photochemical quenching (NPQ) was 281 % higher in the calcified compared to the naked strain, implying higher energy transfer associated with higher NPQ in the presence of calcification. When exposed to natural solar radiation including UV radiation, the maximal quantum yield of photosystem II was only slightly reduced in the calcified strain but strongly reduced in the naked strain. Our results reveal an important role of coccoliths in mitigating light and UV stress in E. huxleyi.

  7. Influence of UV-A or UV-B light and of the nitrogen source on the induction of ferredoxin-dependent glutamate synthase in etiolated tomato cotyledons

    International Nuclear Information System (INIS)

    Migge, A.; Carrayol, E.; Hirel, B.; Lohmann, M.; Meya, G.; Becker, T.W.

    1998-01-01

    The influence of ultraviolet A (UV-A) or B (UV-B) light and of the nitrogen source on the induction of ferredoxin-dependent glutamate synthase (Fd-GOGAT, EC 1.4.7.1) was examined in etiolated cotyledons of tomato (Lycopersicon escu- lentum L.). The Fd-GOGAT activity increased upon illumination of etiolated tomato cotyledons with UV-A or UV-B light. This stimulation of Fd-GOGAT activity was correlated with an increase in both the Fd-GOGAT transcript level and the Fd-GOGAT protein abundance. These results suggest that UV-A or UV-B light stimulates the de novo synthesis of Fd-GOGAT in etiolated tomato cotyledons. Both UV-A and UV-B light failed to influence the activity of NADH-GOGAT (EC 1.4.1.14) in etiolated tomato cotyledons. Taken together, our data indicate that the tomato genes encoding Fd- or NADH-dependent glutamate synthase are regulated differently by UV-A or UV-B light. No difference with respect to both the Fd-GOGAT transcript and protein abundance was found between cotyledons of tomato seedlings grown with either nitrate or ammonium as the sole N-source in the dark or in white light. In addition, the increase in the Fd-GOGAT protein pool induced by white light in etiolated nitrate-grown tomato seedling cotyledons was similar to that induced by white light in etiolated ammonium-grown tomato seedling cotyledons. These results show that the tomato Fd-GOGAT protein level does not depend strongly on the nature of the nitrogen source and that there appears to be no major stimulatory effect on the Fd-GOGAT protein pool produced by nitrate during the illumination of etiolated tomato cotyledons

  8. Effects of UV-B radiation on tetraspores of Chondrus ocellatus Holm (Rhodophyta), and effects of red and blue light on repair of UV-B-induced damage

    Science.gov (United States)

    Ju, Qing; Xiao, Hui; Wang, You; Tang, Xuexi

    2015-05-01

    We evaluated the effects of red and blue light on the repair of UV-B radiation-induced damage in tetraspores of Chondrus ocellatus Holm. Tetraspores of C. ocellatus were treated with different UV-B radiation levels (0, 36, 72, 108, 144 and 180 J/m2), and thereafter subjected to PAR, darkness, or red or blue light during a 2-h repair stage, each day for 48 days. The diameters and cellular contents of cyclobutane pyrimidine dimmers (CPDs), chlorophyll a (Chl a), phycoerythrin, and UV-B-absorbing mycosporinelike amino acids (MAAs) contents of the tetraspores were determined. Our results show that low doses of UV-B radiation (36 and 72 J/m2) promoted the growth of C. ocellatus; however, increased UV-B radiation gradually reduced the C. ocellatus growth (greater than 72 J/m2). The MAAs (palythine and asterina-330) in C. ocellatus were detected and analyzed by LC/MS. Our results suggest that moderate red light could induce the growth of this alga in aquaculture. In addition, photorepair was inhibited by red light, so there may be some other DNA repair mechanism activated by red light. Blue light promoted the activity of DNA photolyase, greatly improving remediation efficiency. Red and blue lights were found to reduce the capacity of C. ocellatus to form MAAs. Therefore, PAR, red light, and blue light play different roles during the repair processes for damage induced by UV-B radiation.

  9. 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

  10. Fundamental Characteristics of Deep-UV Light-Emitting Diodes and Their Application To Control Foodborne Pathogens

    Science.gov (United States)

    Shin, Joo-Yeon; Kim, Soo-Ji; Kim, Do-Kyun

    2015-01-01

    Low-pressure mercury UV (LP-UV) lamps have long been used for bacterial inactivation, but due to certain disadvantages, such as the possibility of mercury leakage, deep-UV-C light-emitting diodes (DUV-LEDs) for disinfection have recently been of great interest as an alternative. Therefore, in this study, we examined the basic spectral properties of DUV-LEDs and the effects of UV-C irradiation for inactivating foodborne pathogens, including Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium, and Listeria monocytogenes, on solid media, as well as in water. As the temperature increased, DUV-LED light intensity decreased slightly, whereas LP-UV lamps showed increasing intensity until they reached a peak at around 30°C. As the irradiation dosage and temperature increased, E. coli O157:H7 and S. Typhimurium experienced 5- to 6-log-unit reductions. L. monocytogenes was reduced by over 5 log units at a dose of 1.67 mJ/cm2. At 90% relative humidity (RH), only E. coli O157:H7 experienced inactivation significantly greater than at 30 and 60% RH. In a water treatment study involving a continuous system, 6.38-, 5.81-, and 3.47-log-unit reductions were achieved in E. coli O157:H7, S. Typhimurium, and L. monocytogenes, respectively, at 0.5 liter per minute (LPM) and 200 mW output power. The results of this study suggest that the use of DUV-LEDs may compensate for the drawbacks of using LP-UV lamps to inactivate foodborne pathogens. PMID:26162872

  11. Fundamental Characteristics of Deep-UV Light-Emitting Diodes and Their Application To Control Foodborne Pathogens.

    Science.gov (United States)

    Shin, Joo-Yeon; Kim, Soo-Ji; Kim, Do-Kyun; Kang, Dong-Hyun

    2016-01-01

    Low-pressure mercury UV (LP-UV) lamps have long been used for bacterial inactivation, but due to certain disadvantages, such as the possibility of mercury leakage, deep-UV-C light-emitting diodes (DUV-LEDs) for disinfection have recently been of great interest as an alternative. Therefore, in this study, we examined the basic spectral properties of DUV-LEDs and the effects of UV-C irradiation for inactivating foodborne pathogens, including Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium, and Listeria monocytogenes, on solid media, as well as in water. As the temperature increased, DUV-LED light intensity decreased slightly, whereas LP-UV lamps showed increasing intensity until they reached a peak at around 30°C. As the irradiation dosage and temperature increased, E. coli O157:H7 and S. Typhimurium experienced 5- to 6-log-unit reductions. L. monocytogenes was reduced by over 5 log units at a dose of 1.67 mJ/cm(2). At 90% relative humidity (RH), only E. coli O157:H7 experienced inactivation significantly greater than at 30 and 60% RH. In a water treatment study involving a continuous system, 6.38-, 5.81-, and 3.47-log-unit reductions were achieved in E. coli O157:H7, S. Typhimurium, and L. monocytogenes, respectively, at 0.5 liter per minute (LPM) and 200 mW output power. The results of this study suggest that the use of DUV-LEDs may compensate for the drawbacks of using LP-UV lamps to inactivate foodborne pathogens. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  12. Influence of light, UV-B radiation, and herbicides on wax biosynthesis of cucumber seedlings

    International Nuclear Information System (INIS)

    Tevini, M.; Steinmüller, D.

    1987-01-01

    The behavior of cuticular alkane-1-ols and alkanes were studied in different developmental stages of cucumber seedlings grown in the dark or under white light, with or without UV-B radiation or in presence of wax biosynthesis inhibitors, trichloroacetic acid and metolachlor. Accumulation of alkane-1-ols increased light independently with seedling age. Synthesis of alkanes was strictly light and dose dependent. Addition of UV-B radiation did not alter the amounts of alkanes or alcohols, however, the distribution of homologues was shifted towards shorter chain homologues. Treatments with Cl 3 AcOH resulted in strong inhibition of alkane accumulation, whereas the amount of alkane-1-ols was changed neither at low nor at moderate concentrations of Cl 3 AcOH but their homologue distribution shifted towards longer chain lengths. This shifting was depressed in the presence of UV-B. At high concentrations of Cl 3 Ac0H similar homologue distributions as produced by UV-B (shift to shorter homologues) were observed. Metolachlor treatment resulted in an inhibition of alkane-1-ol production connected with rising amounts of alkanes, predominantly of short chain species. A simple model of wax biosynthesis is proposed which describes the interactions with white light, UV-B radiation and herbicides. (author)

  13. Drosophila TRPA1 isoforms detect UV light via photochemical production of H2O2

    Science.gov (United States)

    Guntur, Ananya R.; Gu, Pengyu; Takle, Kendra; Chen, Jingyi; Xiang, Yang; Yang, Chung-Hui

    2015-01-01

    The transient receptor potential A1 (TRPA1) channel is an evolutionarily conserved detector of temperature and irritant chemicals. Here, we show that two specific isoforms of TRPA1 in Drosophila are H2O2 sensitive and that they can detect strong UV light via sensing light-induced production of H2O2. We found that ectopic expression of these H2O2-sensitive Drosophila TRPA1 (dTRPA1) isoforms conferred UV sensitivity to light-insensitive HEK293 cells and Drosophila neurons, whereas expressing the H2O2-insensitive isoform did not. Curiously, when expressed in one specific group of motor neurons in adult flies, the H2O2-sensitive dTRPA1 isoforms were as competent as the blue light-gated channelrhodopsin-2 in triggering motor output in response to light. We found that the corpus cardiacum (CC) cells, a group of neuroendocrine cells that produce the adipokinetic hormone (AKH) in the larval ring gland endogenously express these H2O2-sensitive dTRPA1 isoforms and that they are UV sensitive. Sensitivity of CC cells required dTRPA1 and H2O2 production but not conventional phototransduction molecules. Our results suggest that specific isoforms of dTRPA1 can sense UV light via photochemical production of H2O2. We speculate that UV sensitivity conferred by these isoforms in CC cells may allow young larvae to activate stress response—a function of CC cells—when they encounter strong UV, an aversive stimulus for young larvae. PMID:26443856

  14. Influence of UV irradiation on the blue and red light photoinduced processes in azobenzene polyesters

    DEFF Research Database (Denmark)

    Rodríguez, F.J.; Sánchez, C.; Villacampa, B.

    2004-01-01

    light that yields the films into the isotropic state at room temperature (RT) was compared with the quenching from temperatures above the isotropic transition temperature Ti. UV–visible spectra of the thermally quenched films show the presence of aggregates when measured at RT. We have found that UV......Birefringence induced in a series of liquid crystalline side-chain azobenzene polyesters with different substituent groups was investigated under irradiation with 488 and 633 nm linearly polarized lights. Two different initial conditions have been used: the effect of a previous irradiation with UV...

  15. Heat and UV light resistance of vegetative cells and spores of Bacillus subtilis rec-mutants

    International Nuclear Information System (INIS)

    Hanlin, J.H.; Lombardi, S.J.; Slepecky, R.A.

    1985-01-01

    The heat and UV light resistance of spores and vegetative cells of Bacillus subtilis BD170 (rec+) were greater than those of B. subtilis BD224 (recE4). Strain BD170 can repair DNA whereas BD224 is repair deficient due to the presence of the recE4 allele. Spores of a GSY Rec+ strain were more heat resistant than spores of GSY Rec- and Uvr- mutants. The overall level of heat and UV light resistance attained by spores may in part be determined by their ability to repair deoxyribonucleic acid after exposure to these two physical mutagens

  16. Induction of DNA deletions after UV-light irradiation in yeast Saccharomyces cerevisiae

    International Nuclear Information System (INIS)

    Stepanova, A.N.; Koltovaya, N.A.

    2008-01-01

    We study mutagenic action of such a damaging agent as UV light, which can lead to DNA double-strand breaks (DSB). DNA deletions and gross rearrangements occur in process of DSB repair. We show that UV light induces deletion and rearrangement very efficiently. Analysis of efficacy of different types of repair shows that cell tries to repair DSBs with a combination of both homologous recombination (HR) and nonhomologous end joining (NHEJ) if available and that DSB repair by HR is more effective than by NHEJ in growing culture of haploid yeast

  17. Solid-phase photocatalytic degradation of polyethylene-goethite composite film under UV-light irradiation

    International Nuclear Information System (INIS)

    Liu, G.L.; Zhu, D.W.; Liao, S.J.; Ren, L.Y.; Cui, J.Z.; Zhou, W.B.

    2009-01-01

    A novel photodegradable polyethylene-goethite (PE-goethite) composite film was prepared by embedding the goethite into the commercial polyethylene. The degradation of PE-goethite composite films was investigated under ultraviolet light irradiation. The photodegradation activity of the PE plastic was determined by monitoring its weight loss, scanning electron microscopic (SEM) analysis and FT-IR spectroscopy. The weight of PE-goethite (1 wt%) sample steadily decreased and led to the total 16% reduction in 300 h under UV-light intensity for 1 mW/cm 2 . Through SEM observation there were some cavities around the goethite powder in the composite films, but there were few changes except some surface chalking phenomenon in pure PE film. The degradation rate could be controlled by changing the concentration of goethite particles in PE plastic. The degradation of composite plastic initiated on PE-goethite interface and then extended into polymer matrix induced by the diffusion of the reactive oxygen species generated on goethite particle surface. The photocatalytic degradation mechanism of the composite films was briefly discussed.

  18. Instense red phosphors for UV light emitting diode devices.

    Science.gov (United States)

    Cao, Fa-Bin; Tian, Yan-Wen; Chen, Yong-Jie; Xiao, Lin-Jiu; Liu, Yun-Yi

    2010-03-01

    Ca(x)Sr1-x-1.5y-0.5zMoO4:yEu3+ zNa+ red phosphors were prepared by solid-state reaction using Na+ as charge supply for LEDs (light emitting diodes). The content of charge compensator, Ca2+ concentration, synthesis temperature, reaction time, and Eu3+ concentration were the keys to improving the properties of luminescence and crystal structure of red phosphors. The photoluminescence spectra shows the red phosphors are effectively excited at 616 nm by 311 nm, 395 nm, and 465 nm light. The wavelengths of 395 and 465 nm nicely match the widely applied emission wavelengths of ultraviolet or blue LED chips. Its chromaticity coordinates (CIE) are calculated to be x = 0.65, y = 0.32. Bright red light can be observed by the naked eye from the LED-based Ca0.60Sr0.25MoO4:0.08Eu3+ 0.06Na+.

  19. Stabilization of N,N′-bis(3-methylphenyl)-N,N′-bis(phenyl)benzidine thin film morphology with UV light

    Energy Technology Data Exchange (ETDEWEB)

    Tomović, A.Ž.; Markešević, N. [Institute of Physics, University of Belgrade, Pregrevica 118, 11000 Belgrade (Serbia); Scarpellini, M.; Bovio, S. [Interdisciplinary Centre for Nanostructured Materials and Interfaces (CIMAINA), Università di Milano, Via Celoria 16, 20133 Milan (Italy); Lucenti, E. [Interdisciplinary Centre for Nanostructured Materials and Interfaces (CIMAINA), Università di Milano, Via Celoria 16, 20133 Milan (Italy); Institute of Molecular Science and Technology of CNR, via Golgi 19, 20133 Milan (Italy); Milani, P. [Interdisciplinary Centre for Nanostructured Materials and Interfaces (CIMAINA), Università di Milano, Via Celoria 16, 20133 Milan (Italy); Zikic, R. [Institute of Physics, University of Belgrade, Pregrevica 118, 11000 Belgrade (Serbia); Jovanović, V.P., E-mail: vladimir.jovanovic@ipb.ac.rs [Institute of Physics, University of Belgrade, Pregrevica 118, 11000 Belgrade (Serbia); Srdanov, V.I. [Interdisciplinary Centre for Nanostructured Materials and Interfaces (CIMAINA), Università di Milano, Via Celoria 16, 20133 Milan (Italy)

    2014-07-01

    Owing to their low glass transition temperature, T{sub g}, amorphous thin films of N,N′-bis(3-methylphenyl)-N,N′-bis(phenyl)benzidine (TPD) undergo morphological changes even at room temperature. It has been noticed previously that exposure to UV light can increase apparent T{sub g} of TPD films and thus stabilize their morphology. However, the reason behind increase in structural stability was not examined at the time. Here we present evidence that TPD molecules undergo photo-oxidation in air when exposed to λ ≈ 350 nm radiation and that less than 5% of the photo-oxidized species are needed to prevent dewetting of thin TPD films. We propose that photo-oxidized TPD species bind strongly to both ordinary TPD molecules and to terminal hydroxyl groups at the substrate surface, which decreases mobility of TPD molecules and makes thin TPD film less prone to morphology changes. - Highlights: • We made variable thickness TPD films and exposed them to UV light under ambient conditions. • Mass spectroscopy and proton NMR measurements of irradiated and pristine TPD films • TPD molecules undergo oxidation process under UV light irradiation. • Dipole–dipole interactions may be responsible for stabilization of morphological changes.

  20. Comparative assessment of chlorine, heat, ozone, and UV light for killing Legionella pneumophila within a model plumbing system

    International Nuclear Information System (INIS)

    Muraca, P.; Stout, J.E.; Yu, V.L.

    1987-01-01

    Nosocomial Legionnaires disease can be acquired by exposure to the organism from the hospital water distribution system. As a result, many hospitals have instituted eradication procedures, including hypercholorination and thermal eradication. We compared the efficacy of ozonation, UV light, hyperchlorination, and heat eradication using a model plumbing system constructed of copper piping, brass spigots, Plexiglas reservoir, electric hot water tank, and a pump. Legionella pneumophila was added to the system at 10(7) CFU/ml. Each method was tested under three conditions; (i) nonturbid water at 25 degrees C, (ii) turbid water at 25 degrees C, and (iii) nonturbid water at 43 degrees C. UV light and heat killed L. pneumophila most rapidly and required minimal maintenance. Both UV light and heat (60 degrees C) produced a 5 log kill in less than 1 h. In contrast, both chlorine and ozone required 5 h of exposure to produce a 5 log decrease. Neither turbidity nor the higher temperature of 43 degrees C impaired the efficacy of any of the disinfectant methods. Surprisingly, higher temperature enhanced the disinfecting efficacy of chlorine. However, higher temperature accelerated the decomposition of the chlorine residual such that an additional 120% volume of chlorine was required. All four methods proved efficacious in eradicating L. pneumophila from a model plumbing system

  1. Weathering of a carbon nanotube/epoxy nanocomposite under UV light and in water bath: impact on abraded particles

    Science.gov (United States)

    Schlagenhauf, Lukas; Kianfar, Bahareh; Buerki-Thurnherr, Tina; Kuo, Yu-Ying; Wichser, Adrian; Nüesch, Frank; Wick, Peter; Wang, Jing

    2015-11-01

    Weathering processes can influence the surface properties of composites with incorporated nanoparticles. These changes may affect the release behavior of nanoparticles when an abrasion process is applied. Therefore, the influence of two different weathering processes, immersion in water and exposure to UV light, on the properties of abraded particles from a carbon nanotube (CNT)/epoxy nanocomposite was investigated. The investigation included the measurement of the weathering impact on the surface chemistry of the exposed samples, the particle size of abraded particles, the quantity of exposed CNTs in the respirable part of the abraded particles, and the toxicity of abraded particles, measured by in vitro toxicity tests using the THP-1 monocyte-derived macrophages. The results showed that weathering by immersion in water had no influence on the properties of abraded particles. The exposure to UV light caused a degradation of the epoxy on the surface, followed by delamination of an approx. 2.5 μm thick layer. An increased quantity of exposed CNTs in abraded particles was not found; on the contrary, longer UV exposure times decreased the released fraction of CNTs from 0.6% to 0.4%. The toxicity tests revealed that abraded particles from the nanocomposites did not induce additional acute cytotoxic effects compared to particles from the neat epoxy.Weathering processes can influence the surface properties of composites with incorporated nanoparticles. These changes may affect the release behavior of nanoparticles when an abrasion process is applied. Therefore, the influence of two different weathering processes, immersion in water and exposure to UV light, on the properties of abraded particles from a carbon nanotube (CNT)/epoxy nanocomposite was investigated. The investigation included the measurement of the weathering impact on the surface chemistry of the exposed samples, the particle size of abraded particles, the quantity of exposed CNTs in the respirable part of

  2. 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.

  3. Inflammatory Murine Skin Responses to UV-B Light Are Partially Dependent on Endothelin-1 and Mast Cells

    OpenAIRE

    Metz, Martin; Lammel, Verena; Gibbs, Bernhard F.; Maurer, Marcus

    2006-01-01

    Endothelin (ET-1) has been shown to crucially contribute to UV-induced skin responses such as tanning. To test whether ET-1 is also involved in early cutaneous reactions to UV, we assessed ET-1 skin levels in UV-irradiated mice. In correlation with the levels of UV-induced skin inflammation, ET-1 concentrations increased substantially and continually. Moreover, blocking of ET-1 receptors (ETA) resulted in significantly decreased cutaneous inflammation following UV irradiation. When we assesse...

  4. Response of growth and photosynthesis of Emiliania huxleyi to visible and UV irradiances under different light regimes.

    Science.gov (United States)

    Xing, Tao; Gao, Kunshan; Beardall, John

    2015-01-01

    Microalgae are capable of acclimating to changes in light and ultraviolet radiation (UVR, 280-400 nm). However, little is known about how the ecologically important coccolithophore Emiliania huxleyi responds to UVR when acclimated to different light regimes. Here, we grew E. huxleyi under indoor constant light or fluctuating sunlight with or without UVR, and investigated its growth, photosynthetic performance and pigmentation. Under the indoor constant light regime, the specific growth rate (μ) was highest, while fluctuating outdoor solar radiation significantly decreased the growth rate. Addition of UVR further decreased the growth rate. The repair rate of photosystem II (PSII), as reflected in changes in PSII quantum yield, showed an inverse correlation with growth rate. Cells grown under the indoor constant light regime exhibited the lowest repair rate, while cells from the outdoor fluctuating light regimes significantly increased their repair rate. Addition of UVR increased both the repair rate and intracellular UV-absorbing compounds. This increased repair capability, at the cost of decreased growth rate, persisted after the cells were transferred back to the indoor again, suggesting an enhanced allocation of energy and resources for repair of photosynthetic machinery damage by solar UVR which persisted for a period after transfer from solar UVR. © 2014 The American Society of Photobiology.

  5. Red light emitting solid state hybrid quantum dot-near-UV GaN LED devices

    International Nuclear Information System (INIS)

    Song, Hongjoo; Lee, Seonghoon

    2007-01-01

    We produced core-shell (CdSe)ZnSe quantum dots by direct colloidal chemical synthesis and the surface-passivation method-an overcoating of the core CdSe with a larger-bandgap material ZnSe. The (CdSe)ZnSe quantum dots(QDs) play the role of a colour conversion centre. We call these quantum dots nanophosphors. We fabricated red light emitting hybrid devices of (CdSe)ZnSe QDs and a near-UV GaN LED by combining red light emitting (CdSe)ZnSe quantum dots (as a colour conversion centre) with a near-UV(NUV) GaN LED chip (as an excitation source). A few good red phosphors have been known for UV excitation wavelengths, and red phosphors for UV excitation have been sought for a long time. Here we tested the possibility of using (CdSe)ZnSe QDs as red nanophosphors for UV excitation. The fabricated red light emitting hybrid device of (CdSe)ZnSe and a NUV GaN LED chip showed a good luminance. We demonstrated that the (CdSe)ZnSe quantum dots were promising red nanophosphors for NUV excitation and that a red LED made of QDs and a NUV excitation source was a highly efficient hybrid device

  6. Effects of UV light disinfection on antibiotic-resistant coliforms in wastewater effluents

    International Nuclear Information System (INIS)

    Meckes, M.C.

    1982-01-01

    Total coliforms and total coliforms resistant to streptomycin, tetracycline, or chloramphenicol were isolated from filtered activated sludge effluents before and after UV light irradiation. Although the UV irradiation effectively disinfected the wastewater effluent, the percentage of the total surviving coliform population resistant to tetracycline or chloramphenicol was significantly higher than the percentage of the total coliform population resistant to those antibiotics before UV irradiation. This finding was attributed to the mechanism of R-factor mediated resistance to tetracycline. No significant difference was noted for the percentage of the surviving total coliform population resistant to streptomycin before or after UV irradiation. Multiple drug resistant to patterns of 300 total coliform isolates revealed that 82% were resistant to two or more antibiotics. Furthermore, 46% of these isolates were capable of transferring antibiotic resistance to a sensitive strain of Escherichia coli

  7. Selenium inhibits UV-light-induced skin carcinogenesis in hairless mice

    International Nuclear Information System (INIS)

    Overvad, Kim; Thorling, E.B.; Bjerring, Peter; Ebbesen, Peter

    1985-01-01

    Female hairless inbred hr/hr mice were exposed to UV-B irradiation from Philips TL 40W/13 fluorescent tubes. Fractionated irradiation, given as single daily doses 5 days a week, was gradually increased from 0.04 to 0.4 J/cm 2 over 2 weeks. Irradiation at 0.4 J/cm 2 was continued for 20 weeks. Selenium supplementation given as sodium selenite in the drinking water at 2, 4 and 8 mg/l began 3 weeks before UV-irradiation and continued thereafter. Development of skin tumors was followed by weekly examinations. Statistical analyses revealed significant dose-dependent selenium-mediated protection against UV-light-induced skin cancer. Leukemia developed in 5 of 150 UV-irradiated mice as opposed to none in a group of 60 unirradiated mice. (author)

  8. Inactivation of bacteria via photosensitization of vitamin K3 by UV-A light.

    Science.gov (United States)

    Xu, Fei; Vostal, Jaroslav G

    2014-09-01

    This study investigated inactivation of bacteria with ultraviolet light A irradiation in combination with vitamin K3 as a photosensitizer. Six bacteria including Bacillus cereus, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis, Klebsiella pneumoniae, and Escherichia coli suspended in vitamin K3 aqueous solution were exposed to ultraviolet light A. Five of six bacteria, with the exception of Pseudomonas aeruginosa, were reduced by eight logs with 1600 μM of vitamin K3 and 5.8 J cm(-2) UV-A irradiation. Pseudomonas aeruginosa was reduced by four logs under these conditions. Reactive oxygen species including singlet oxygen, hydroxyl radical and superoxide anion radical were generated in vitamin K3 aqueous solution under UV-A irradiation. These results suggest that vitamin K3 and UV-A irradiation may be effective for bacterial inactivation in environmental and medical applications. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

  9. Photodegradation of diphenylarsinic acid by UV-C light: Implication for its remediation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Anan; Teng, Ying [Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China); Hu, Xuefeng [Key Laboratory of Coastal Zone Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003 (China); Wu, Longhua; Huang, Yujuan [Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China); Luo, Yongming, E-mail: ymluo@yic.ac.cn [Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China); Key Laboratory of Coastal Zone Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003 (China); Christie, Peter [Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China)

    2016-05-05

    Highlights: • DPAA can be degraded into inorganic arsenics under the irradiation of UV-C light. • The photodegradation of DPAA mainly depended on its direct photolysis. • The {sup 1}O{sub 2} was generated, but had little effect on DPAA photolysis. • Cl{sup −} promoted the photolytic rate of DPAA, but NO{sub 3}{sup −}, NO{sub 2}{sup −} and HA inhibited it. - Abstract: Diphenylarsinic acid (DPAA) is a major contaminant in environments polluted by chemical weapons and abandoned after World Wars I and II and poses high risks to biota but remediation methods for this contaminant are rare. Here, the photodegradtion of DPAA was studied under high-pressure Hg lamp irradiation. DPAA was degraded completely into inorganic arsenic species in 30 min under UV-C irradiation. The photodegradation of DPAA depended mainly on its direct photolysis through excited-state DPAA. By contrast, the generation of {sup 1}O{sub 2} during the photodegradation of DPAA was confirmed by electron paramagnetic resonance (EPR) studies, but {sup 1}O{sub 2} had little effect on the photodegradation of DPAA. Phtotodegradation of DPAA was also studied in soil leachates and groundwater and the photolytic rate of DPAA was controlled by the total organic carbon (TOC) content in soil leachates and by the NO{sub 3}{sup −} concentration in groundwater. Finally, studies on the effects of common solutes on the photodegradation of DPAA show that Cl{sup −} can increase the photolytic rate of DPAA by prolonging the lifetime of excited-state DPAA. Moreover, NO{sub 3}{sup −}, NO{sub 2}{sup −}, and humic acid (HA) can decrease the photolytic rate of DPAA by suppressing the production of excited-state DPAA. This research shows the detailed mechanism of DPAA photodegradation and provides a new and effective method for DPAA decontamination.

  10. Development of Efficient UV-LED Phosphor Coatings for Energy Saving Solid State Lighting

    International Nuclear Information System (INIS)

    Uwe Happek

    2006-01-01

    The University of Georgia, in collaboration with GE Global Research, has investigated the relevant quenching mechanism of phosphor coatings used in white light devices based on UV LEDs. The final goal of the project was the design and fabrication of a high-efficacy white light UV-LED device through improved geometry and optimized phosphor coatings. At the end of the research period, which was extended to seamlessly carry over the research to a follow-up program, we have demonstrated a two-fold improvement in the conversion efficiency of a white light LED device, where the increase efficacy is due to both improved phosphor quantum efficiency and lamp geometry. Working prototypes have been displayed at DOE sponsored meetings and during the final presentation at the DOE Headquarters in Washington, DC. During the first phase of the project, a fundamental understanding of quenching processes in UV-LEDs was obtained, and the relationships that describe the performance of the phosphor as a function of photon flux, temperature, and phosphor composition were established. In the second phase of the project, these findings were then implemented to design the improved UV-LED lamp. In addition, our research provides a road map for the design of efficient white light LEDs, which will be an important asset during a follow-up project led by GE

  11. Light interaction with nano-structured diatom frustule, from UV-A to NIR

    DEFF Research Database (Denmark)

    Maibohm, Christian; Nielsen, Josefine Holm; Rottwitt, Karsten

    2016-01-01

    symmetry where morphological parameters vary between the different investigated species. We report how light interacts with the frustule in the wavelength range from UV-A (320-380 nm) to NIR (900 nm). High resolution spectroscopy and CCD images are used to identify photoluminescence (PL) and variations...

  12. Bromodeoxyuridine combined with UV light and gamma irradiation promotes the production of asymmetric somatic hybrid calli

    International Nuclear Information System (INIS)

    Trick, H.N.; Bates, G.W.

    1996-01-01

    The degree of gamma‐ or X‐ray‐induced donor chromosome elimination in asymmetric somatic hybrids is highly variable. Here the beneficial use of bromodeoxyuridine and UV light as additional chromosome destabilizing agents is described. Protoplasts of Nicotiana tabacum were fused with protoplasts of Nicotiana plumbaginifolia (Np) that carried the kanamycin‐resistance and glucuronidase (GUS) genes on separate chromosomes. Prior to fusion, the Np donor protoplasts were pretreated with bromodeoxyuridine and then were inactivated by treatment with iodoacetate ± UV light ± 200 Gy gamma irradiation. Hybrids were selected on medium containing kanamycin. The elimination of Np DNA was assessed by scoring of the fraction of hybrid calli that expressed GUS and by dot‐blot analysis using a Np‐specific probe. gamma irradiation alone resulted in elimination of 50% of Np DNA. Pretreatment with bromodeoxyuridine (10 μM) followed by 2.5 to 5 min UV light resulted in the elimination of 35–45% of the donor genome, but incorporation of bromodeoxyuridine (10 μM) followed by 2,5 to 5 min UV light and 200 Gy gamma irradiation resulted in 85 to 90% elimination of Np DNA

  13. Patterning and Conductivity Modulation of Conductive Polymers by UV Light Exposure

    DEFF Research Database (Denmark)

    Edberg, Jesper; Iandolo, Donata; Brooke, Robert

    2016-01-01

    to control the conductivity in the conjugated polymer poly(3,4-ethylenedioxythiophene):tosylate by more than six orders of magnitude in addition to producing high-resolution patterns and optical gradients. The mechanism behind the modulation in the polymerization kinetics by UV light irradiation as well...

  14. Understanding Xeroderma Pigmentosum Complementation Groups Using Gene Expression Profiling after UV-Light Exposure.

    Science.gov (United States)

    Bowden, Nikola A; Beveridge, Natalie J; Ashton, Katie A; Baines, Katherine J; Scott, Rodney J

    2015-07-14

    Children with the recessive genetic disorder Xeroderma Pigmentosum (XP) have extreme sensitivity to UV-light, a 10,000-fold increase in skin cancers from age 2 and rarely live beyond 30 years. There are seven genetic subgroups of XP, which are all resultant of pathogenic mutations in genes in the nucleotide excision repair (NER) pathway and a XP variant resultant of a mutation in translesion synthesis, POLH. The clinical symptoms and severity of the disease is varied across the subgroups, which does not correlate with the functional position of the affected protein in the NER pathway. The aim of this study was to further understand the biology of XP subgroups, particularly those that manifest with neurological symptoms. Whole genome gene expression profiling of fibroblasts from each XP complementation group was assessed before and after UV-light exposure. The biological pathways with altered gene expression after UV-light exposure were distinct for each subtype and contained oncogenic related functions such as perturbation of cell cycle, apoptosis, proliferation and differentiation. Patients from the subgroups XP-B and XP-F were the only subgroups to have transcripts associated with neuronal activity altered after UV-light exposure. This study will assist in furthering our understanding of the different subtypes of XP which will lead to better diagnosis, treatment and management of the disease.

  15. Marginal eyespots on butterfly wings deflect bird attacks under low light intensities with UV wavelengths.

    Directory of Open Access Journals (Sweden)

    Martin Olofsson

    2010-05-01

    Full Text Available Predators preferentially attack vital body parts to avoid prey escape. Consequently, prey adaptations that make predators attack less crucial body parts are expected to evolve. Marginal eyespots on butterfly wings have long been thought to have this deflective, but hitherto undemonstrated function.Here we report that a butterfly, Lopinga achine, with broad-spectrum reflective white scales in its marginal eyespot pupils deceives a generalist avian predator, the blue tit, to attack the marginal eyespots, but only under particular conditions-in our experiments, low light intensities with a prominent UV component. Under high light intensity conditions with a similar UV component, and at low light intensities without UV, blue tits directed attacks towards the butterfly head.In nature, birds typically forage intensively at early dawn, when the light environment shifts to shorter wavelengths, and the contrast between the eyespot pupils and the background increases. Among butterflies, deflecting attacks is likely to be particularly important at dawn when low ambient temperatures make escape by flight impossible, and when insectivorous birds typically initiate another day's search for food. Our finding that the deflective function of eyespots is highly dependent on the ambient light environment helps explain why previous attempts have provided little support for the deflective role of marginal eyespots, and we hypothesize that the mechanism that we have discovered in our experiments in a laboratory setting may function also in nature when birds forage on resting butterflies under low light intensities.

  16. Marginal eyespots on butterfly wings deflect bird attacks under low light intensities with UV wavelengths.

    Science.gov (United States)

    Olofsson, Martin; Vallin, Adrian; Jakobsson, Sven; Wiklund, Christer

    2010-05-24

    Predators preferentially attack vital body parts to avoid prey escape. Consequently, prey adaptations that make predators attack less crucial body parts are expected to evolve. Marginal eyespots on butterfly wings have long been thought to have this deflective, but hitherto undemonstrated function. Here we report that a butterfly, Lopinga achine, with broad-spectrum reflective white scales in its marginal eyespot pupils deceives a generalist avian predator, the blue tit, to attack the marginal eyespots, but only under particular conditions-in our experiments, low light intensities with a prominent UV component. Under high light intensity conditions with a similar UV component, and at low light intensities without UV, blue tits directed attacks towards the butterfly head. In nature, birds typically forage intensively at early dawn, when the light environment shifts to shorter wavelengths, and the contrast between the eyespot pupils and the background increases. Among butterflies, deflecting attacks is likely to be particularly important at dawn when low ambient temperatures make escape by flight impossible, and when insectivorous birds typically initiate another day's search for food. Our finding that the deflective function of eyespots is highly dependent on the ambient light environment helps explain why previous attempts have provided little support for the deflective role of marginal eyespots, and we hypothesize that the mechanism that we have discovered in our experiments in a laboratory setting may function also in nature when birds forage on resting butterflies under low light intensities.

  17. UV light selectively coinduces supply pathways from primary metabolism and flavonoid secondary product formation in parsley

    Science.gov (United States)

    Logemann, Elke; Tavernaro, Annette; Schulz, Wolfgang; Somssich, Imre E.; Hahlbrock, Klaus

    2000-01-01

    The UV light-induced synthesis of UV-protective flavonoids diverts substantial amounts of substrates from primary metabolism into secondary product formation and thus causes major perturbations of the cellular homeostasis. Results from this study show that the mRNAs encoding representative enzymes from various supply pathways are coinduced in UV-irradiated parsley cells (Petroselinum crispum) with two mRNAs of flavonoid glycoside biosynthesis, encoding phenylalanine ammonia-lyase and chalcone synthase. Strong induction was observed for mRNAs encoding glucose 6-phosphate dehydrogenase (carbohydrate metabolism, providing substrates for the shikimate pathway), 3-deoxyarabinoheptulosonate 7-phosphate synthase (shikimate pathway, yielding phenylalanine), and acyl-CoA oxidase (fatty acid degradation, yielding acetyl-CoA), and moderate induction for an mRNA encoding S-adenosyl-homocysteine hydrolase (activated methyl cycle, yielding S-adenosyl-methionine for B-ring methylation). Ten arbitrarily selected mRNAs representing various unrelated metabolic activities remained unaffected. Comparative analysis of acyl-CoA oxidase and chalcone synthase with respect to mRNA expression modes and gene promoter structure and function revealed close similarities. These results indicate a fine-tuned regulatory network integrating those functionally related pathways of primary and secondary metabolism that are specifically required for protective adaptation to UV irradiation. Although the response of parsley cells to UV light is considerably broader than previously assumed, it contrasts greatly with the extensive metabolic reprogramming observed previously in elicitor-treated or fungus-infected cells. PMID:10677554

  18. Characterization of DNA-repair potential in deep subsurface bacteria challenged by UV light, hydrogen peroxide, and gamma radiation

    OpenAIRE

    Arrage, Andrew Anthony

    1991-01-01

    Subsurface bacterial isolates obtained through the DOE Subsurface Science Program were tested for resistance to UV light, gamma radiation and H202. Some deep subsurface bacteria were resistant to UV light, demonstrating â ¥1.0% survival at fluences which resulted in a 0.0001% survival level of E. coli B. The percentage of UV resistant aerobic subsurface bacteria and surface soil bacteria were similar; 30.8% and 25.8% respectively. All of the microaerophilic subsurface isolates ...

  19. Recovery from DNA synthesis in V 79 chinese hamster cells irradiated with UV light

    International Nuclear Information System (INIS)

    Ventura, A.M.

    1987-01-01

    Mammalian cells recover from DNA synthesis inhibition by UV light before most of the pyrimidine dimers have been removed from the genome. Most of the rodent cells show a deficient dimer excision repair compared with normal human fibroblasts. Despite this fact they recover efficiently from DNA synthesis inhibition after UV. In Chinese hamster V 79 cells was found that this recovery takes place in the absence of a significant excision repair, and it seems to be directly coupled to a recovery in the rate of movement of the replication fork. 120 refs, 31 figs. (author)

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

    Science.gov (United States)

    Hanada, Yasutaka; Sugioka, Koji; Midorikawa, Katsumi

    2010-01-18

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

  1. Transition metal-modified zinc oxides for UV and visible light photocatalysis.

    Science.gov (United States)

    Bloh, J Z; Dillert, R; Bahnemann, D W

    2012-11-01

    In order to use photocatalysis with solar light, finding more active and especially visible light active photocatalysts is a very important challenge. Also, studies of these photocatalysts should employ a standardized test procedure so that their results can be accurately compared and evaluated with one another. A systematic study of transition metal-modified zinc oxide was conducted to determine whether they are suitable as visible light photocatalysts. The photocatalytic activity of ZnO modified with eight different transition metals (Cu, Co, Fe, Mn, Ni, Ru, Ti, Zr) in three different concentrations (0.01, 0.1, and 1 at.%) was investigated under irradiation with UV as well as with visible light. The employed activity test is the gas-phase degradation of acetaldehyde as described by the ISO standard 22197-2. The results suggest that the UV activity can be improved with almost any modification element and that there exists an optimal modification ratio at about 0.1 at.%. Additionally, Mn- and Ru-modified ZnO display visible light activity. Especially the Ru-modified ZnO is highly active and surpasses the visible light activity of all studied titania standards. These findings suggest that modified zinc oxides may be a viable alternative to titanium dioxide-based catalysts for visible light photocatalysis. Eventually, possible underlying mechanisms are proposed and discussed.

  2. Phosphors for near UV-Emitting LED's for Efficacious Generation of White Light

    Energy Technology Data Exchange (ETDEWEB)

    McKittrick, Joanna [Univ. of California, San Diego, CA (United States)

    2013-09-30

    1) We studied phosphors for near-UV (nUV) LED application as an alternative to blue LEDs currently being used in SSL systems. We have shown that nUV light sources could be very efficient at high current and will have significantly less binning at both the chip and phosphor levels. We identified phosphor blends that could yield 4100K lamps with a CRI of approximately 80 and LPWnUV,opt equal to 179 for the best performing phosphor blend. Considering the fact that the lamps were not optimized for light coupling, the results are quite impressive. The main bottleneck is an optimum blue phosphor with a peak near 440 nm with a full width half maximum of about 25 nm and a quantum efficiency of >95%. Unfortunately, that may be a very difficult task when we want to excite a phosphor at ~400 nm with a very small margin for Stokes shift. Another way is to have all the phosphors in the blend having the excitation peak at 400 nm or slightly shorter wavelength. This could lead to a white light source with no body color and optimum efficacy due to no self-absorption effects by phosphors in the blend. This is even harder than finding an ideal blue phosphor, but not necessarily impossible. 2) With the phosphor blends identified, light sources using nUV LEDs at high current could be designed with comparable efficacy to those using blue LEDs. It will allow us to design light sources with multiple wattages using the same chips and phosphor blends simply by varying the input current. In the case of blue LEDs, this is not currently possible because varying the current will lower the efficacy at high current and alter the color point. With improvement of phosphor blends, control over CRI could improve. Less binning at the chip level and also at the phosphor blend level could reduce the cost of SSL light sources. 3) This study provided a deeper understanding of phosphor characteristics needed for LEDs in general and nUV LEDs in particular. Two students received Ph.D. degrees and three

  3. Photocatalytic activity of Fe-doped CaTiO₃ under UV-visible light.

    Science.gov (United States)

    Yang, He; Han, Chong; Xue, Xiangxin

    2014-07-01

    The photocatalytic degradation of methylene blue (MB) over Fe-doped CaTiO₃ under UV-visible light was investigated. The as-prepared samples were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS) system, Fourier transform infrared spectra (FT-IR), and UV-visible diffuse reflectance spectroscopy (DRS). The results show that the doping with Fe significantly promoted the light absorption ability of CaTiO₃ in the visible light region. The Fe-doped CaTiO₃ exhibited higher photocatalytic activity than CaTiO₃ for the degradation of MB. However, the photocatalytic activity of the Fe-doped CaTiO₃ was greatly influenced by the calcination temperature during the preparation process. The Fe-doped CaTiO₃ prepared at 500°C exhibited the best photocatalytic activity, with degradation of almost 100% MB (10ppm) under UV-visible light for 180 min. Copyright © 2014. Published by Elsevier B.V.

  4. Properties of the Visible Light Phototaxis and UV Avoidance Behaviors in the Larval Zebrafish.

    Science.gov (United States)

    Guggiana-Nilo, Drago A; Engert, Florian

    2016-01-01

    For many organisms, color is an essential source of information from visual scenes. The larval zebrafish has the potential to be a model for the study of this topic, given its tetrachromatic retina and high dependence on vision. In this study we took a step toward understanding how the larval zebrafish might use color sensing. To this end, we used a projector-based paradigm to force a choice of a color stimulus at every turn of the larva. The stimuli used spanned most of the larval spectral range, including activation of its Ultraviolet (UV) cone, which has not been described behaviorally before. We found that zebrafish larvae swim toward visible wavelengths (>400 nm) when choosing between them and darkness, as has been reported with white light. However, when presented with UV light and darkness zebrafish show an intensity dependent avoidance behavior. This UV avoidance does not interact cooperatively with phototaxis toward longer wavelengths, but can compete against it in an intensity dependent manner. Finally, we show that the avoidance behavior depends on the presence of eyes with functional UV cones. These findings open future avenues for studying the neural circuits that underlie color sensing in the larval zebrafish.

  5. UV light-induced thermoluminescence of Er + Li doped ZrO2

    International Nuclear Information System (INIS)

    Hristov, H; Arhangelova, N; Velev, V; Penev, I; Bello, M; Moschini, G; Uzunov, N

    2010-01-01

    Analysis of the thermoluminescence (TL) properties of ZrO 2 doped with Eu and Li has been conducted. Different quantities of lithium co-dopant have been added as Li 2 CO 3 to a mixture of ZrO 2 with 1wt% Er. Pellets sintered at a temperature of 1200 0 C have been prepared and the kinetic parameters of the phosphors have been studied after irradiation with UV light. It has been shown that the addition of 8 to 10 wt% of Li to the mixture of ZrO 2 with 1wt% Er yields a maximum intensity of the peaks at 65 0 C and at 105 0 C. Spectral emission and spectral sensitivity of the phosphors have been studied. The analysis applied to TL glow curves, obtained from the UV irradiated phosphors and kept after the irradiation at different times in a dark storage, revealed that the peaks at 65 0 C and 105 0 C have relatively long fading. It is concluded that the phosphors thus obtained possess a good sensitivity to the UV emission and could be appropriate phosphors for detection and quantitative measurements of UV light.

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

    DEFF Research Database (Denmark)

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

    2006-01-01

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

  7. Induction of anthocyanin formation and of enzymes related to its biosynthesis by UV light in cell cultures of Haplopappus gracilis

    International Nuclear Information System (INIS)

    Wellmann, E.; Hrazdina, G.; Grisebach, H.

    1976-01-01

    Only UV light below 345 nm stimulates anthocyanin formation in dark grown cell suspension cultures of Haplopappus gracilis. A linear relationship between UV dose and flavonoid accumulation, as found previously with parsley cell cultures was not observed with the H.gracilis cells. Only continuous irradiation with high doses of UV was effective. Drastic increases in the activities of the enzymes phenylalanine ammonia-lyase, chalcone isomerase and flavanone synthase were observed under continuous UV light. The increase in enzyme activities paralleled anthocyanin formation. (author)

  8. Synthesis of spherical Ag/ZnO heterostructural composites with excellent photocatalytic activity under visible light and UV irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Hairui, E-mail: liuhairui1@126.com [College of Physics & Electronics Engineering, Henan Normal University, Henan Key Laboratory of Photovoltaic Materials, Xinxiang 453007 (China); Hu, Yanchun [College of Physics & Electronics Engineering, Henan Normal University, Henan Key Laboratory of Photovoltaic Materials, Xinxiang 453007 (China); Zhang, Zhuxia [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan, Shanxi 030024 (China); College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024 (China); Liu, Xuguang [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan, Shanxi 030024 (China); Jia, Husheng [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan, Shanxi 030024 (China); College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024 (China); Xu, Bingshe [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan, Shanxi 030024 (China)

    2015-11-15

    B) solution under ultraviolet (UV) and visible light irradiation. The rate of degradation of the as-prepared Ag/ZnO composites was more than triple times faster than that of pure ZnO-MSs under UV light, which was ascribed to the formation of Schottky barriers in the regions between Ag-NPs and ZnO-MSs. Furthermore, Ag/ZnO composites exhibit superior photocatalytic activity over ZnO-MSs in the visible light region owing to the effective electron transfer from plasmon-excited Ag(0) nanoparticles to ZnO-MSs by strong localization of surface plasmon resonance (SPR). This can effectively decrease the recombination of electron–hole pairs, lead to a prolonged lifetime of the electron–holes pairs that promotes the degradation efficiency. The chemical stability and reusability of Ag/ZnO powders were also investigated.

  9. Synthesis of spherical Ag/ZnO heterostructural composites with excellent photocatalytic activity under visible light and UV irradiation

    International Nuclear Information System (INIS)

    Liu, Hairui; Hu, Yanchun; Zhang, Zhuxia; Liu, Xuguang; Jia, Husheng; Xu, Bingshe

    2015-01-01

    B) solution under ultraviolet (UV) and visible light irradiation. The rate of degradation of the as-prepared Ag/ZnO composites was more than triple times faster than that of pure ZnO-MSs under UV light, which was ascribed to the formation of Schottky barriers in the regions between Ag-NPs and ZnO-MSs. Furthermore, Ag/ZnO composites exhibit superior photocatalytic activity over ZnO-MSs in the visible light region owing to the effective electron transfer from plasmon-excited Ag(0) nanoparticles to ZnO-MSs by strong localization of surface plasmon resonance (SPR). This can effectively decrease the recombination of electron–hole pairs, lead to a prolonged lifetime of the electron–holes pairs that promotes the degradation efficiency. The chemical stability and reusability of Ag/ZnO powders were also investigated.

  10. Investigation of L(+)-Ascorbic Acid with Raman Spectroscopy in Visible and UV Light

    DEFF Research Database (Denmark)

    Berg, Rolf W.

    2015-01-01

    Abstract: Raman spectroscopy investigations of l(+)-ascorbic acid and its mono- and di-deprotonated anions (AH(-) and A(2-)) are reviewed and new measurements reported with several wavelengths, 229, 244, 266, 488, and 532nm. Results are interpreted, assisted by new DFT/B3LYP quantum chemical calc......). Relatively weak preresonance enhancement was seen for A(2-) when excitation was done with 229nm UV light, allowing water bands to become observable as for normal visible light Raman spectra....... calculations with 6-311++G(d,p) basis sets for several conformations of ascorbic acid and the anions. Raman spectra were measured during titration with NaOH base in an oxygen-poor environment to avoid fluorescence when solutions were alkaline. The ultraviolet (UV) absorption band for ascorbic acid in aqueous......cm(-1). Finally, for the ascorbate di-anion, absorption was found at similar to 298.4nm with molar absorptivity of similar to 7,000 L mol(-1) cm(-1) and below similar to 220nm. With UV light (244 and 266nm), strongly basic solutions gave pronounced Raman resonance enhancement at similar to 1556cm(-1...

  11. Ferric ion mediated photochemical decomposition of perfluorooctanoic acid (PFOA) by 254 nm UV light

    International Nuclear Information System (INIS)

    Wang Yuan; Zhang Pengyi; Pan Gang; Chen Hao

    2008-01-01

    The great enhancement of ferric ion on the photochemical decomposition of environmentally persistent perfluorooctanoic acid (PFOA) under 254 nm UV light was reported. In the presence of 10 μM ferric ion, 47.3% of initial PFOA (48 μM) was decomposed and the defluorination ratio reached 15.4% within 4 h reaction time. While the degradation and defluorination ratio greatly increased to 80.2% and 47.8%, respectively, when ferric ion concentration increased to 80 μM, and the corresponding half-life was shortened to 103 min. Though the decomposition rate was significantly lowered under nitrogen atmosphere, PFOA was efficiently decomposed too. Other metal ions like Cu 2+ and Zn 2+ also slightly improved the photochemical decomposition of PFOA under irradiation of 254 nm UV light. Besides fluoride ion, other intermediates during PFOA decomposition including formic acid and five shorter-chain perfluorinated carboxylic acids (PFCAs) with C7, C6, C5, C4 and C3, respectively, were identified and quantified by IC or LC/MS. The mixture of PFOA and ferric ion had strong absorption around 280 nm. It is proposed that PFOA coordinates with ferric ion to form a complex, and its excitation by 254 nm UV light leads to the decomposition of PFOA in a stepwise way

  12. UV light induced photodegradation of organic dye by ZnO nanocatalysts

    International Nuclear Information System (INIS)

    Sumesh, C. K.; Patel, Bhavin; Parekh, Kinnari

    2013-01-01

    Ultraviolet light induced photocatalytic activity of ZnO nanocatalyst prepared using a wet chemical precipitation route and mineralization of the methyl orange (MO) dye has been carried out in a photocatalytic reactor. The degradation of the MO was monitored spectrophotometrically and showed a decolorization efficiency of 92% after nine hours of irradiation in the MO-ZnO/UV light system. The blue shifting of maximum peak position of the MO and the formation of extra peak at 247 nm during irradiation time advances revealed that MO degrades in the form of intermediates during the photocatalytic process.

  13. The study of temperature and UV light effect in anthocyanin extract from dragon fruit (Hylocereus costaricensis) rind using UV-Visible spectrophotometer

    Science.gov (United States)

    Purbaningtias, Tri Esti; Aprilia, Anisa Cahyani; Fauzi'ah, Lina

    2017-12-01

    This study aimed to determine the total of anthocyanin content in ethanol extract from super red dragon fruit rind. The extraction was affected by temperature and light conditions. The determination of anthocyanin's total content was performed with a variation of pH and analyzed by UV-Visible spectrophotometer. The results showed that the average contained total anthocyanins obtained at room temperature, 40 and 60 °C were 4.6757, 5.6108, 21.9757 mg/L, respectively. In higher temperatures, it was observed the more anthocyanin extracted. The concentration of anthocyanin extract without UV light was 2.5716 mg/L, it was less than UV light assisted extract, i.e. 5.3770 mg / L.

  14. CuS/RGO hybrid photocatalyst for full solar spectrum photoreduction from UV/Vis to near-infrared light.

    Science.gov (United States)

    Wu, Jie; Liu, Baibai; Ren, Zhenxing; Ni, Mengying; Li, Can; Gong, Yinyan; Qin, Wei; Huang, Yongli; Sun, Chang Q; Liu, Xinjuan

    2018-05-01

    To make full use of the solar energy, it remains a great challenge for semiconductor photocatalysts to harvest the full solar light spectrum from ultraviolet (UV) to visible even the near infrared (NIR) wavelength. Here we show firstly the CuS/RGO (reduced graphene oxide) hybrid photocatalyst synthesized via a microwave assisted method with full solar light (UV-Vis-NIR) active for efficient Cr(VI) reduction. The CuS/RGO displays high absorption and catalytic activity in the UV, visible and even the NIR light regions. As co-catalyst, RGO can separate and inhibit the recombination of charge carriers, consequently improving the catalytic activity. Only 1wt% RGO emersions can reduce 90% of Cr(VI) under the radiation of light over the full spectrum. Findings may provide a new strategy and substance to expand the utilization range of solar light from UV to visible even the NIR energy. Copyright © 2017. Published by Elsevier Inc.

  15. Efficacy of hand held, inexpensive UV light sources on Acanthamoeba, causative organism in amoebic keratitis

    Directory of Open Access Journals (Sweden)

    Ivan Cometa

    2010-01-01

    /protocols might capitalize on this synergistic action.Keywords: UV light sources, amoebic keratitis, MPS

  16. Decolourisation of simulated reactive dyebath effluents by electrochemical oxidation assisted by UV light.

    Science.gov (United States)

    López-Grimau, V; Gutiérrez, M C

    2006-01-01

    This study is focused on the optimisation of the electrochemical decolourisation of textile effluents containing reactive dyes with the aim of making feasible-technically and economically-this method at industrial scale. Coloured waters were treated in continuous at low current density, to reduce the electrical consumption. Ti/PtO(x) electrodes were used to oxidize simulated dyebaths prepared with an azo/dichlorotriazine reactive dye (C.I. Reactive Orange 4). The decolourisation yield was dependent on the dyeing electrolyte (NaCl or Na(2)SO(4)). Dyeing effluents which contained from 0.5 to 20 gl(-1) of NaCl reached a high decolourisation yield, depending on the current density, immediately after the electrochemical process. These results were improved when the effluents were stored for several hours under solar light. After the electrochemical treatment the effluents were stored in a tank and exposed under different lighting conditions: UV light, solar light and darkness. The evolution of the decolourisation versus the time of storage was reported and kinetic constants were calculated. The time of storage was significantly reduced by the application of UV light. A dye mineralization study was also carried out on a concentrated dyebath. A TOC removal of 81% was obtained when high current density was applied for a prolonged treatment with recirculation. This treatment required a high electrical consumption.

  17. Action of UV-A and blue light on enzymes activity and accumulation of lipid peroxidation products in attached and detached frog retinas

    Science.gov (United States)

    Lapina, Victoria A.; Doutsov, Alexander E.

    1994-07-01

    The effect of the UV-A and blue light on the accumulation of lipid peroxidation products and activities of succinate dehydrogenase and superoxide dismutase in the retina was examined in eye cup model of dark and light adapted frogs R. temporaria. Retinas were exposed to UV-A radiation (8 mW/cm2) and blue light (10 to 150 mW/cm2) for periods from 5 min to 1 hr. We have measured TBA-active products both in the retina homogenates and in the reaction media. Enzyme activities was measured in the retina homogenates only. The measurements revealed a significant increase in the endogenous and exogenous forms of lipid peroxidation products in the retina of dark adapted frog (1.6+/- 0.4; 1.4+/- 0.3 nmole TBA-active products per mg protein, respectively) compared to light adapted (0.85+/- 0.16; 0.32+/- 0.06 nmole TBA-active products per mg protein, respectively). In the same conditions succinate dehydrogenase activity was decline more than 50% but superoxide dismutase activity didn't decrease. Disorganized inner and outer segments were observed after 40 min exposures. No light microscopic changes were detected after 5 min exposures. Light damage was significantly higher in the retina of dark adapted frog. The results indicate that the retina from eye cup of dark adapted frog is more susceptible to UV-A and blue light damages.

  18. Penetration of UV-A, UV-B and blue light through the leaf trichome layers of two xeromorphic plants, olive and oak, measured by optical fibre microprobes

    International Nuclear Information System (INIS)

    Karabourniotis, G.; Bornman, J.F.

    1999-01-01

    Quartz fibre-optic microprobes were used to monitor the light microenvironment beneath trichome layers of the xeromorphic leaves of two Mediterranean evergreen sclerophylls, Olea europaea and Quercus ilex. Young developing leaves of both plants were densely pubescent on both surfaces of the lamina, whereas the mature leaves were pubescent only on the abaxial side. Trichome layers of young as well as of mature leaves of both plants attenuated almost all incident ultraviolet (UV)-B (310 nm) and UV-A (360 nm) radiation and a considerable portion of blue light (430 nm). Abaxial trichome layers of young leaves were more effective in screening out the incident radiation compared to the adaxial ones of the same leaves and also compared to the abaxial layer of the mature leaves. The abaxial epidermis of dehaired mature leaves of O. europaea was ineffective in absorbing most of the incident UV-B and UV-A radiation. UV and visible spectra beneath trichome layers of O. europaea in mature leaves confirmed that the light microenvironment on the epidermis was deprived in the UV-B, UV-A and partly in the blue spectral regions. It is proposed that the occurrence of a dense trichome layer, especially in young leaves, may play a protective role against not only UV-B radiation damage, but also against high visible irradiance. This function is performed irrespective of the differing anatomy of individual hairs of both plants. The protection provided by the trichomes could afford advantages under stress conditions, especially during leaf development. (author)

  19. The imprints of the high light and UV-B stresses in Oryza sativa L. 'Kanchana' seedlings are differentially modulated.

    Science.gov (United States)

    Faseela, Parammal; Puthur, Jos T

    2018-01-01

    High light and ultraviolet-B radiation (UV-B) are generally considered to have negative impact on photosynthesis and plant growth. The present study evaluates the tolerance potential of three cultivars of Oryza sativa L. (Kanchana, Mattatriveni and Harsha) seedlings towards high light and UV-B stress on the basis of photosynthetic pigment degradation, chlorophyll a fluorescence parameters and rate of lipid peroxidation, expressed by malondialdehyde content. Surprisingly, it was revealed that Kanchana was the most sensitive cultivar towards high light and at the same time it was the most tolerant cultivar towards UV-B stress. This contrasting feature of Kanchana towards high light and UV-B tolerance was further studied by analyzing photosystem (PS) I and II activity, mitochondrial activity, chlorophyll a fluorescence transient, enzymatic and non-enzymatic antioxidant defense system. Due to the occurrence of more PS I and PSII damages, the inhibition of photochemical efficiency and emission of dissipated energy as heat or fluorescence per PSII reaction center was higher upon high light exposure than UV-B treatments in rice seedlings of Kanchana. The mitochondrial activity was also found to be drastically altered upon high light as compared to UV-B treatments. The UV-B induced accumulation of non-enzymatic antioxidants (proline, total phenolics, sugar and ascorbate) and enzymatic antioxidants (ascorbate peroxidase, guaiacol peroxidase, superoxide dismutase and glutathione reductase) in rice seedlings than those subjected to high light exposure afforded more efficient protection against UV-B radiation in rice seedlings. Our results proved that high tolerance of Kanchana towards UV-B than high light treatments, correlated linearly with the protected photosynthetic and mitochondrial machinery which was provided by upregulation of antioxidants particularly by total phenolics, ascorbate and ascorbate peroxidase in rice seedlings. Data presented in this study conclusively

  20. The effects of UV light on calcium metabolism in ball pythons (Python regius).

    Science.gov (United States)

    Hedley, J; Eatwell, K

    2013-10-12

    Despite the popularity of keeping snakes in captivity, there has been limited investigation into the effects of UV radiation on vitamin D levels in snakes. The aim of this study was to investigate the effects of UV-b radiation on plasma 25-hydroxyvitamin D3 levels and ionised calcium concentrations in ball pythons (Python regius). Blood samples were taken from 14 ball pythons, which had never been exposed to UV-b light, to obtain baseline 25-hydroxyvitamin D3 levels and ionised calcium concentrations. Blood samples were then taken again from the same snakes 70 days later after one group (Group 1, n=6 females) were exposed to UV-b radiation daily, and the other group (Group 2, n=5 males and 3 females) were exposed to no UV-b radiation. Mean±sd 25-hydroxyvitamin D3 levels on day 0 in Group 1 were 197±35 nmol/l, and on day 70 were 203.5±13.8 nmol/l. Mean±sd 25-hydroxyvitamin D3 levels in Group 2 on day 0 were 77.7±41.5 nmol/l, and on day 70 were 83.0±41.9 nmol/l. Mean±sd ionised calcium levels at day 0 were 1.84±0.05 mmol/l for Group 1, and on day 70 were 1.78±0.07 mmol/l. Mean±sd ionised calcium levels at day 0 were 1.79±0.07 mmol/l for Group 2, and on day 70 were 1.81±0.05 mmol/l. No association was demonstrated between exposure to UV-b radiation and plasma 25-hydroxyvitamin D3 and ionised calcium concentrations. These results may provide baseline parameters for future studies in this and other snake species to determine ability to utilise UV-b light for vitamin D production.

  1. Growth and characterization of ammonium nickel-cobalt sulfate Tutton's salt for UV light applications

    Science.gov (United States)

    Ghosh, Santunu; Oliveira, Michelle; Pacheco, Tiago S.; Perpétuo, Genivaldo J.; Franco, Carlos J.

    2018-04-01

    We have obtained a set of sample crystals of the family of Tutton's salt comprise in the isomorphic series with general chemical formula (NH4)2NixCo(1-x) (SO4)2·6H2O, by employing growth from solutions by slow evaporation technique. The samples crystals were characterized by ICP-AES, X-ray powder diffraction analysis, thermogravimetric analysis, UV-Vis-NIR, Raman and FTIR spectroscopy. This type of material has been studied because of its physical and chemical properties not yet understood and they have potential technological applications. Chemical analysis of the samples by ICP-AES method allowed us to investigate the efficiency of the method of growth used. Thermogravimetric analysis provides the information about the thermal stability of the obtained crystals for high temperature applications, and powder X-ray diffraction analysis at ambient and high temperature reveals the structural quality and structural change of the samples respectively. We have used Raman spectroscopy in the range 100-4000 cm-1 and FTIR spectroscopy in the range 400-4000 cm-1 to understand the internal vibrational mode of the octahedral complexes [Ni(H2O)6]2+ and [Co(H2O)6]2+, SO42- and NH4+ tetrahedra. The transmittance of our mixed ammonium nickel cobalt sulfate hexahydrate (ACNSH) crystals is 75% in the UV region, which indicates that they are ideal to use in UV light filters and UV sensors.

  2. Towards an electronic nose based on nano-structured transition metal oxides activated by a tuneable UV light source

    CSIR Research Space (South Africa)

    Mwakikunga, B

    2011-10-01

    Full Text Available Traditional gas sensors involve heating the sensor material for gas selectivity. New gas approaches require activation by a broadband UV light source. The authors propose to employ a tuneable UV source in which this source is tuned for its many...

  3. In-vivo data on the influence of tobacco smoke and UV light on murine skin.

    Science.gov (United States)

    Pavlou, P; Rallis, M; Deliconstantinos, G; Papaioannou, G; Grando, S A

    2009-01-01

    Inhaled tobacco smoke comes in direct contact with few organs such as mouth, lungs, and stomach. Cigarette smoke (CS) in lungs has been extensively studied. However, limited data exist on its effect on skin, and there are no long-term experimental studies suggesting toxic effects on skin. Even though it is generally accepted that CS is among the main factors of skin aging, the number of experimental studies showing this aging effect is limited. We hereby studied the effect of long-term exposure to CS on the skin of hairless mice in combination with or without ultraviolet (UV) light. In addition, we investigated potential skin protection by a potent antioxidant namely procyanidine-rich French maritime pine bark extract (PBE) pycnogenol. Male and female hairless SKH-2 mice were exposed for 10 months to tobacco smoke and/or UV light in vivo, and their effects on skin were investigated. Some biophysical parameters such as development of erythema, transepidermal water loss (TEWL), and skin elasticity were measured. The results show that UV and CS may be acting synergistically, as shown by the enhanced TEWL, erythema values, epitheliomas, and squamous cell carcinomas (SCCs) observed, whereas PBE seems to protect skin against SCC.

  4. The Use of Ultra-Violet (UV) Light Emitting Diodes (LEDS) in an Advanced Oxidation Process (AOP) with Brilliant Blue FCF as an Indicator

    Science.gov (United States)

    2015-03-26

    LEDs have the potential to replace mercury lamps in many UV processes, as well as open the door to new applications of UV light based on their unique...al. 2007, Autin, Romelot, et al. 2013). UV LEDs in AOPs While most data on AOP experimentation are based on experiments that use mercury lamps ...metaldehyde in solution. Their experiments found that similar UV light exposure levels from UV LEDs and traditional mercury lamps produced similar

  5. Synthesis of CdSe-TiO_2 Photocatalyst and Their Enhanced Photocatalytic Activities under UV and Visible Light

    International Nuclear Information System (INIS)

    Lim, Chang Sung; Chen, Ming Liang; Oh, Won Chun

    2011-01-01

    In this study, CdSe-TiO_2 photocatalyst were synthesized by a facile solvothermal method and characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis and UV-vis diffuse reflectance spectrophotometer. The photocatalytic activity was investigated by degrading methylene blue (MB) in aqueous solution under irradiation of UV light as well as visible light. The absorbance of degraded MB solution was determined by UV-vis spectrophotometer. The results revealed that the CdSe- TiO_2 photocatalyst exhibited much higher photocatalytic activity than TiO_2 both under irradiation of UV light as well as visible light

  6. Near-visible light and UV photoprotection in the treatment of melasma: a double-blind randomized trial.

    Science.gov (United States)

    Castanedo-Cazares, Juan Pablo; Hernandez-Blanco, Diana; Carlos-Ortega, Blanca; Fuentes-Ahumada, Cornelia; Torres-Álvarez, Bertha

    2014-02-01

    Melasma is an acquired hyperpigmentation on sun-exposed areas. Multiple approaches are used to treat it, but all include broad ultraviolet (UV)-spectrum sunscreens. Visible light (VL) can induce pigmentary changes similar to those caused by UV radiation on darker-skinned patients. To assess the efficacy of sunscreen with broad-spectrum UV protection that contains iron oxide as a VL-absorbing pigment (UV-VL) compared with a regular UV-only broad-spectrum sunscreen for melasma patients exposed to intense solar conditions. Sixty-eight patients with melasma were randomized in two groups to receive either UV-VL sunscreen or UV-only sunscreen, both with sun protection factor ≥ 50, over 8 weeks. All patients received 4% hydroquinone as a depigmenting treatment. At onset and at conclusion of the study, they were assessed by the Melasma Activity and Severity Index (MASI; a subjective scale), colorimetry (L*) and histological analysis of melanin. Sixty-one patients concluded the study. At 8 weeks, the UV-VL group showed 15%, 28% and 4% greater improvements than the UV-only group in MASI scores, colorimetric values and melanin assessments, respectively. UV-VL sunscreen enhances the depigmenting efficacy of hydroquinone compared with UV-only sunscreen in treatment of melasma. These findings suggest a role for VL in melasma pathogenesis. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  7. UV-visible light-activated Ag-decorated, monodisperse TiO2 aggregates for treatment of the pharmaceutical oxytetracycline.

    Science.gov (United States)

    Han, Changseok; Likodimos, Vlassis; Khan, Javed Ali; Nadagouda, Mallikarjuna N; Andersen, Joel; Falaras, Polycarpos; Rosales-Lombardi, Pablo; Dionysiou, Dionysios D

    2014-10-01

    Noble metal Ag-decorated, monodisperse TiO2 aggregates were successfully synthesized by an ionic strength-assisted, simple sol-gel method and were used for the photocatalytic degradation of the antibiotic oxytetracycline (OTC) under both UV and visible light (UV-visible light) irradiation. The synthesized samples were characterized by X-ray diffraction analysis (XRD); UV-vis diffuse reflectance spectroscopy; environmental scanning electron microscopy (ESEM); transmission electron microscopy (TEM); high-resolution TEM (HR-TEM); micro-Raman, energy-dispersive X-ray spectroscopy (EDS); and inductively coupled plasma optical emission spectrometry (ICP-OES). The results showed that the uniformity of TiO2 aggregates was finely tuned by the sol-gel method, and Ag was well decorated on the monodisperse TiO2 aggregates. The absorption of the samples in the visible light region increased with increasing Ag loading that was proportional to the amount of Ag precursor added in the solution over the tested concentration range. The Brunauer, Emmett, and Teller (The BET) surface area slightly decreased with increasing Ag loading on the TiO2 aggregates. Ag-decorated TiO2 samples demonstrated enhanced photocatalytic activity for the degradation of OTC under UV-visible light illumination compared to that of pure TiO2. The sample containing 1.9 wt% Ag showed the highest photocatalytic activity for the degradation of OTC under both UV-visible light and visible light illumination. During the experiments, the detected Ag leaching for the best TiO2-Ag photocatalyst was much lower than the National Secondary Drinking Water Regulation for Ag limit (0.1 mg L(-1)) issued by the US Environmental Protection Agency.

  8. UV light-emitting-diode photochemical mercury vapor generation for atomic fluorescence spectrometry.

    Science.gov (United States)

    Hou, Xiaoling; Ai, Xi; Jiang, Xiaoming; Deng, Pengchi; Zheng, Chengbin; Lv, Yi

    2012-02-07

    A new, miniaturized and low power consumption photochemical vapor generation (PVG) technique utilizing an ultraviolet light-emitting diode (UV-LED) lamp is described, and further validated via the determination of trace mercury. In the presence of formic acid, the mercury cold vapor is favourably generated from Hg(2+) solutions by UV-LED irradiation, and then rapidly transported to an atomic fluorescence spectrometer for detection. Optimum conditions for PVG and interferences from concomitant elements were investigated in detail. Under optimum conditions, a limit of detection (LOD) of 0.01 μg L(-1) was obtained, and the precision was better than 3.2% (n = 11, RSD) at 1 μg L(-1) Hg(2+). No obvious interferences from any common ions were evident. The methodology was successfully applied to the determination of mercury in National Research Council Canada DORM-3 fish muscle tissue and several water samples.

  9. Epidermal Rac1 regulates the DNA damage response and protects from UV-light-induced keratinocyte apoptosis and skin carcinogenesis

    Science.gov (United States)

    Deshmukh, Jayesh; Pofahl, Ruth; Haase, Ingo

    2017-01-01

    Non-melanoma skin cancer (NMSC) is the most common type of cancer. Increased expression and activity of Rac1, a small Rho GTPase, has been shown previously in NMSC and other human cancers; suggesting that Rac1 may function as an oncogene in skin. DMBA/TPA skin carcinogenesis studies in mice have shown that Rac1 is required for chemically induced skin papilloma formation. However, UVB radiation by the sun, which causes DNA damage, is the most relevant cause for NMSC. A potential role of Rac1 in UV-light-induced skin carcinogenesis has not been investigated so far. To investigate this, we irradiated mice with epidermal Rac1 deficiency (Rac1-EKO) and their controls using a well-established protocol for long-term UV-irradiation. Most of the Rac1-EKO mice developed severe skin erosions upon long-term UV-irradiation, unlike their controls. These skin erosions in Rac1-EKO mice healed subsequently. Surprisingly, we observed development of squamous cell carcinomas (SCCs) within the UV-irradiation fields. This shows that the presence of Rac1 in the epidermis protects from UV-light-induced skin carcinogenesis. Short-term UV-irradiation experiments revealed increased UV-light-induced apoptosis of Rac1-deficient epidermal keratinocytes in vitro as well as in vivo. Further investigations using cyclobutane pyrimidine dimer photolyase transgenic mice revealed that the observed increase in UV-light-induced keratinocyte apoptosis in Rac1-EKO mice is DNA damage dependent and correlates with caspase-8 activation. Furthermore, Rac1-deficient keratinocytes showed reduced levels of p53, γ-H2AX and p-Chk1 suggesting an attenuated DNA damage response upon UV-irradiation. Taken together, our data provide direct evidence for a protective role of Rac1 in UV-light-induced skin carcinogenesis and keratinocyte apoptosis probably through regulating mechanisms of the DNA damage response and repair pathways. PMID:28277539

  10. Epidermal Rac1 regulates the DNA damage response and protects from UV-light-induced keratinocyte apoptosis and skin carcinogenesis.

    Science.gov (United States)

    Deshmukh, Jayesh; Pofahl, Ruth; Haase, Ingo

    2017-03-09

    Non-melanoma skin cancer (NMSC) is the most common type of cancer. Increased expression and activity of Rac1, a small Rho GTPase, has been shown previously in NMSC and other human cancers; suggesting that Rac1 may function as an oncogene in skin. DMBA/TPA skin carcinogenesis studies in mice have shown that Rac1 is required for chemically induced skin papilloma formation. However, UVB radiation by the sun, which causes DNA damage, is the most relevant cause for NMSC. A potential role of Rac1 in UV-light-induced skin carcinogenesis has not been investigated so far. To investigate this, we irradiated mice with epidermal Rac1 deficiency (Rac1-EKO) and their controls using a well-established protocol for long-term UV-irradiation. Most of the Rac1-EKO mice developed severe skin erosions upon long-term UV-irradiation, unlike their controls. These skin erosions in Rac1-EKO mice healed subsequently. Surprisingly, we observed development of squamous cell carcinomas (SCCs) within the UV-irradiation fields. This shows that the presence of Rac1 in the epidermis protects from UV-light-induced skin carcinogenesis. Short-term UV-irradiation experiments revealed increased UV-light-induced apoptosis of Rac1-deficient epidermal keratinocytes in vitro as well as in vivo. Further investigations using cyclobutane pyrimidine dimer photolyase transgenic mice revealed that the observed increase in UV-light-induced keratinocyte apoptosis in Rac1-EKO mice is DNA damage dependent and correlates with caspase-8 activation. Furthermore, Rac1-deficient keratinocytes showed reduced levels of p53, γ-H2AX and p-Chk1 suggesting an attenuated DNA damage response upon UV-irradiation. Taken together, our data provide direct evidence for a protective role of Rac1 in UV-light-induced skin carcinogenesis and keratinocyte apoptosis probably through regulating mechanisms of the DNA damage response and repair pathways.

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

    International Nuclear Information System (INIS)

    Nagy, P.; Fischl, G.

    2002-01-01

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

  12. A Photodegradation Study of Three Common Paint and Plaster Biocides under monochromatic UV Light

    DEFF Research Database (Denmark)

    Minelgaite, Greta; Vollertsen, Jes; Nielsen, Asbjørn Haaning

    2014-01-01

    Photodegradation of the three common paint-and-plaster biocides (carbendazim, diuron and terbutryn) was investigated at controlled laboratory conditions. Samples prepared in two types of water (demineralized water and pond water) were subjected to 254 nm monochromatic UV light. Light intensity (W m......-2) in the experimental chamber was measured by a fiber optic spectrometer. The observed decline in biocide concentration was related with the light energy, accumulated during the time of degradation (kJ m-2), and 1st order photodegradation rate constants (m2 kJ-1) were determined. The obtained...... at selected laboratory conditions, as well as emphasize the importance of water type when investigating pollutant’s photo fate, as certain constituents might act as reaction enhancers or inhibitors....

  13. Blue lighting decreases the amount of food consumed in men, but not in women.

    Science.gov (United States)

    Cho, Sungeun; Han, Ashley; Taylor, Michael H; Huck, Alexandria C; Mishler, Amanda M; Mattal, Kyle L; Barker, Caleb A; Seo, Han-Seok

    2015-02-01

    Previous research has demonstrated that colors of lighting can modulate participants' motivation to consume the food placed under the lighting. This study was designed to determine whether the colors of lighting can affect the amount of food consumed, in addition to sensory perception of the food. The influence of lighting color was also compared between men and women. One-hundred twelve participants (62 men and 50 women) were asked to consume a breakfast meal (omelets and mini-pancakes) under one of three different lighting colors: white, yellow, and blue. During the test, hedonic impression of the food's appearance, willingness to eat, overall flavor intensity and overall impression of the food, and meal size (i.e., the amount of food consumed) were measured. Blue lighting decreased the hedonic impression of the food's appearance, but not the willingness to eat, compared to yellow and white lighting conditions. The blue lighting significantly decreased the amount consumed in men, but not in women, compared to yellow and white lighting conditions. Overall flavor intensity and overall impression of the food were not significantly different among the three lighting colors. In conclusion, this study provides empirical evidence that the color of lighting can modulate the meal size. In particular, blue lighting can decrease the amount of food eaten in men without reducing their acceptability of the food. Published by Elsevier Ltd.

  14. Photochemical Synthesis of Complex Carbazoles: Evaluation of Electronic Effects in Both UV- and Visible-Light Methods in Continuous Flow.

    Science.gov (United States)

    Hernandez-Perez, Augusto C; Caron, Antoine; Collins, Shawn K

    2015-11-09

    An evaluation of both a visible-light- and UV-light-mediated synthesis of carbazoles from various triarylamines with differing electronic properties under continuous-flow conditions has been conducted. In general, triarylamines bearing electron-rich groups tend to produce higher yields than triarylamines possessing electron-withdrawing groups. The incorporation of nitrogen-based heterocycles, as well as halogen-containing arenes in carbazole skeletons, was well tolerated, and often synthetically useful complementarity was observed between the UV-light and visible-light (photoredox) methods. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Cu-doped TiO2 nanoparticles enhance survival of Shewanella oneidensis MR-1 under Ultraviolet Light (UV) exposure

    International Nuclear Information System (INIS)

    Wu, Bing; Zhuang, Wei-Qin; Sahu, Manoranjan; Biswas, Pratim; Tang, Yinjie J.

    2011-01-01

    It has been shown that photocatalytic TiO 2 nanoparticles (NPs) can be used as an efficient anti-microbial agent under UV light due to generation of reactive oxygen species (ROS), while Shewanella oneidensis MR-1 is a metal-reducing bacterium highly susceptible to UV radiation. Interestingly, we found that the presence of Cu-doped TiO 2 NPs in the cultural medium dramatically increased the survival rates (based on colony-forming unit) of strain MR-1 by over 10,000-fold (incubation without shaking) and ∼ 200 fold (incubation with shaking) after a 2-h exposure to UV light. Gene expression results (via qPCR measurement) indicated that the DNA repair gene recA in MR-1 was significantly induced by UV exposure (indicating cellular damage under UV stress), but the influence of NPs on recA expression was not statistically evident. Plausible explanations to NP attenuation of UV stresses are: 1. TiO 2 based NPs are capable of scattering and absorbing UV light and thus create a shading effect to protect MR-1 from UV radiation; 2. more importantly, Cu-doped TiO 2 NPs can co-agglomerate with MR-1 to form large flocs that improves cells' survival against the environmental stresses. This study improves our understanding of NP ecological impacts under natural solar radiation and provides useful insights to application of photocatalytic-NPs for bacterial disinfection.

  16. Computer numerical control (CNC) lithography: light-motion synchronized UV-LED lithography for 3D microfabrication

    International Nuclear Information System (INIS)

    Kim, Jungkwun; Allen, Mark G; Yoon, Yong-Kyu

    2016-01-01

    This paper presents a computer-numerical-controlled ultraviolet light-emitting diode (CNC UV-LED) lithography scheme for three-dimensional (3D) microfabrication. The CNC lithography scheme utilizes sequential multi-angled UV light exposures along with a synchronized switchable UV light source to create arbitrary 3D light traces, which are transferred into the photosensitive resist. The system comprises a switchable, movable UV-LED array as a light source, a motorized tilt-rotational sample holder, and a computer-control unit. System operation is such that the tilt-rotational sample holder moves in a pre-programmed routine, and the UV-LED is illuminated only at desired positions of the sample holder during the desired time period, enabling the formation of complex 3D microstructures. This facilitates easy fabrication of complex 3D structures, which otherwise would have required multiple manual exposure steps as in the previous multidirectional 3D UV lithography approach. Since it is batch processed, processing time is far less than that of the 3D printing approach at the expense of some reduction in the degree of achievable 3D structure complexity. In order to produce uniform light intensity from the arrayed LED light source, the UV-LED array stage has been kept rotating during exposure. UV-LED 3D fabrication capability was demonstrated through a plurality of complex structures such as V-shaped micropillars, micropanels, a micro-‘hi’ structure, a micro-‘cat’s claw,’ a micro-‘horn,’ a micro-‘calla lily,’ a micro-‘cowboy’s hat,’ and a micro-‘table napkin’ array. (paper)

  17. Non-melanoma skin cancer: occupational risk from UV light and arsenic exposure.

    Science.gov (United States)

    Surdu, Simona

    2014-01-01

    Non-melanoma skin cancer (NMSC) has a significant impact on public health and health care costs as a result of high morbidity and disfigurement due to the destruction of surrounding tissues. Although the mortality rates of these tumors are low, the high incidence rates determine a considerable number of deaths. NMSC is the most common type of skin cancer, representing about 1/3 of all malignancies diagnosed worldwide each year. The most common NMSC are basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). Studies on humans and experimental animals indicate that ultraviolet (UV) light and arsenic play important roles in the development of these skin malignancies. Several epidemiological studies have investigated the risk of developing NMSC and the potential link between exposure to sunlight and arsenic in the agricultural and industrial occupational settings. To date, the published literature suggests that there is no apparent skin cancer risk as regards workplace exposure to artificial UV light or arsenic. Concerning UV light from sun exposure at the workplace, most published studies indicated an elevated risk for SCC, but are less conclusive for BCC. Many of these studies are limited by the methodology used in the evaluation of occupational exposure and the lack of adjustment for major confounders. Therefore, further epidemiological studies are required to focus on exposure assessment at the individual level as well as potential interactions with other occupational and non-occupational exposures and individual susceptibility. In doing so, we can better quantify the true risk of skin cancer in exposed workers and inform effective public health prevention programs.

  18. Antibodies to uv light denatured DNA in systemic lupus erythematosus: detection by filter radioimmunoassay and clinical correlations

    Energy Technology Data Exchange (ETDEWEB)

    Davis, P; Russell, A S; Percy, J S

    1976-12-01

    Antibodies to ultraviolet light denatured DNA (UV DNA) have been measured in patients with systemic lupus erythematosus (SLE) and normal subjects, using a millipore filter radioimmunoassay. High levels of UV DNA binding were only found in patients with SLE. The presence of UV DNA antibodies correlated well with the presence of native DNA antibodies, although immunodiffusion studies and inhibition techniques showed these antibodies to be immunologically distinct in many cases. Forty-one percent of the SLE patients had had photosensitivity at some stage of their disease, but there was a poor correlation between this symptom and the presence of UV DNA antibodies. Although UV DNA is known to be a potent immunogen, none of the results from this study suggests that antibodies to UV DNA are more than another example of the broad spectrum of antinuclear antibodies seen in SLE.

  19. Surface functionalisation of polypyrrole films using UV light induced radical activation

    International Nuclear Information System (INIS)

    Lisboa, P.; Gilliland, D.; Ceccone, G.; Valsesia, A.; Rossi, F.

    2006-01-01

    Electrochemically deposited polypyrrole (PPy) films were functionalised with amine or carboxylic function. The functionalisation was done by grafting allylamine or acrylic acid (AAc) using UV light radical activation. The active groups of the surface were quantified by X-ray photoelectron spectroscopy (XPS) after chemical derivatisation with trifluoroethanol (TFE) or 4-trifluoromethylbenzaldehyde (TFBA), respectively. Grafting with AAc completely covered the PPy film introducing high levels of carboxylic function. In the case of allylamine grafting, a saturation point at low amine carbon level was achieved. Further characterisation of the surfaces was done by time of flight secondary ion mass spectroscopy (TOF-SIMS), atomic force microscope (AFM) and scanning electron microscope (SEM)

  20. The genetic origins of biosynthesis and light-responsive control of the chemical UV screen of land plants

    International Nuclear Information System (INIS)

    Jorgensen, R.

    1994-01-01

    Most land plants possess the capacity to protect themselves from UV light, and do so by producing pigments that absorb efficiently in the UV-A and UV-B regions of the spectrum while allowing transmission of nearly all photosynthetically useful wavelengths. These UV-absorbing pigments are mainly phenylpropanoids and flavonoids. This chapter summarizes current understanding of the mechanism of UV protection in higher land plants, evaluates the information available from lower land plants and their green-algal relatives, and then considers the possible evolutionary origins of this use of chemical filters for selectively screening UV light from solar radiation. It is proposed that photo control over the biosynthesis of UV-absorbing phenylpropanoids and flavonoids may have evolved in concert with the evolution of the high biosynthetic activity necessary for UV protection. The toxicity of phenylpropanoids and flavonoids has been postulated to have been a barrier to the evolution of an effective chemical UV screen, and that some means for sequestering these compounds and/or for controlling their synthesis probably evolved prior to, or in concert with, the evolution of high rates of biosynthesis. The original photoreceptor and signal transduction system is speculated to have been based on photo isomerization of a phenylpropanoid ester and a pre-existing product feedback mechanism for controlling phenylpropanoid biosynthesis. Understanding the original mechanism for photo control of the chemical UV screen of land plants could be valuable for understanding the adaptability of extant land plants to rising levels of solar UV-B radiation and may suggest genetic strategies for engineering improved UV tolerance in crop plants. (author)

  1. UV light-induced survival response in a highly radiation-resistant isolate of the Moraxella-acinetobacter group

    International Nuclear Information System (INIS)

    Keller, L.C.; Thompson, T.L.; Maxcy, R.B.

    1982-01-01

    A highly radiation-resistant member of the Moraxella-Acinetobacter group, isolate 4, obtained from meat, was studied to determine the effect of preexposure to UV radiation on subsequent UV light resistance. Cultures that were preexposed to UV light and incubated for a short time in plate count broth exhibited increased survival of a UV light challenge dose. This response was inhibited in the presence of chloramphenicol. Frequencies of mutation to streptomycin, trimethoprim, and sulfanilamide resistance remained the same after the induction of this survival response and were not altered by treatment with mutagens, with the exception of mutation to streptomycin resistance after γ-irradiation or nitrosoguanidine or methyl methane sulfonate treatment. The results indicated that isolate 4 has a UV light-inducible UV light resistance mechanism which is not associated with increased mutagenesis. The characteristics of the radiation resistance response in this organism are similar to those of certain other common food contaminants. Therefore, considered as part of the total microflora of meat, isolate 4 and the other radiation-resistant Moraxella-Acinetobacter isolates should not pose unique problems in a proposed radappertizaton process

  2. Super Water-Repellent Fractal Surfaces of a Photochromic Diarylethene Induced by UV Light

    Science.gov (United States)

    Izumi, Norikazu; Minami, Takayuki; Mayama, Hiroyuki; Takata, Atsushi; Nakamura, Shinichiro; Yokojima, Satoshi; Tsujii, Kaoru; Uchida, Kingo

    2008-09-01

    Photochromic diarylethene forms super water-repellent surfaces upon irradiation with UV light. Microfibril-like crystals grow on the solid diarylethene surface after UV irradiation, and the contact angle of water on the surface becomes larger with increasing surface roughness with time. The fractal analysis was made by the box-counting method for the rough surfaces. There are three regions in the roughness size having the fractal dimension of ca. 2.4 (size of roughness smaller than 5 µm), of ca. 2.2 (size of roughness between 5-40 µm), and of ca. 2.0 (size of roughness larger than 40 µm). The fractal dimension of ca. 2.4 was due to the fibril-like structures generated gradually by UV irradiation on diarylethene surfaces accompanied with an increase in the contact angle. The surface structure with larger fractal dimension mainly contributes to realizing the super water-repellency of the diarylethene surfaces. This mechanism of spontaneous formation of fractal surfaces is similar to that for triglyceride and alkylketene dimer waxes.

  3. Interaction of sunscreen TiO2 nanoparticles with skin and UV light: penetration, protection, phototoxicity

    Science.gov (United States)

    Popov, Alexey; Lademann, Jürgen; Priezzhev, Alexander; Myllylä, Risto

    2009-07-01

    Titanium dioxide (TiO2) nanoparticles are extensively used nowadays in sunscreens as protective compounds for human skin from UV radiation. In this paper, such particles are investigated from the viewpoint of penetration into living skin, UV protective properties (compared with silicon (Si) particles) and as sources of free radicals if UV-irradiated. We show that: a) even after multiple applications, the particles are located within the uppermost 3-μm-thick part of the skin; b) the optimal sizes are found to be 62 nm and 55 nm, respectively for TiO2 and Si particles for 310-nm light and, correspondingly, 122 and 70 nm - for 400-nm radiation; c) if applied onto glass, small particles of 25 nm in diameter produce an increased amount of free radicals compared to the larger ones of 400 nm in diameter and placebo itself; however, if applied onto porcine skin in vitro, there is no statistically distinct difference in the amount of radicals generated by the two kinds of particles on skin and by the skin itself. This proves that although particles as part of sunscreens produce free radicals, the effect is negligible in comparison to the production of radicals by skin in vitro.

  4. Photothermal Activation of Metal-Organic Frameworks Using a UV-Vis Light Source.

    Science.gov (United States)

    Espín, Jordi; Garzón-Tovar, Luis; Carné-Sánchez, Arnau; Imaz, Inhar; Maspoch, Daniel

    2018-03-21

    Metal-organic frameworks (MOFs) usually require meticulous removal of the solvent molecules to unlock their potential porosity. Herein, we report a novel one-step method for activating MOFs based on the photothermal effect induced by directly irradiating them with a UV-vis lamp. The localized light-to-heat conversion produced in the MOF crystals upon irradiation enables a very fast solvent removal, thereby significantly reducing the activation time to as low as 30 min and suppressing the need for time-consuming solvent-exchange procedures and vacuum conditions. This approach is successful for a broad range of MOFs, including HKUST-1, UiO-66-NH 2 , ZIF-67, CPO-27-M (M = Zn, Ni, and Mg), Fe-MIL-101-NH 2 , and IRMOF-3, all of which exhibit absorption bands in the light emission range. In addition, we anticipate that this photothermal activation can also be used to activate covalent organic frameworks (COFs).

  5. Atmospheric fate of oil matter adsorbed on sea salt particles under UV light

    Science.gov (United States)

    Vaitilingom, M.; Avij, P.; Huang, H.; Valsaraj, K. T.

    2014-12-01

    The presence of liquid petroleum hydrocarbons at the sea water surface is an important source of marine pollution. An oil spill in sea-water will most likely occur due to an involuntary accident from tankers, offshore platforms, etc. However, a large amount of oil is also deliberately spilled in sea-water during the clean-out process of tank vessels (e.g. for the Mediterranean Sea, 490,000 tons/yr). Moreover, the pollution caused by an oil spill does not only affect the aquatic environment but also is of concern for the atmospheric environment. A portion of the oil matter present at the sea-water surface is transported into the atmosphere viaevaporation and adsorption at the surface of sea spray particles. Few studies are related to the presence of oil matter in airborne particles resulting from their adsorption on sea salt aerosols. We observed that the non-volatile oil matter was adsorbed at the surface of sea-salt crystals (av. size of 1.1 μm). Due to their small size, these particles can have a significant residence time in the atmosphere. The hydrocarbon matter adsorbed at the surface of these particles can also be transformed by catalyzers present in the atmosphere (i.e. UV, OH, O3, ...). In this work, we focused on the photo-oxidation rates of the C16 to C30alkanes present in these particles. We utilized a bubble column reactor, which produced an abundance of small sized bubbles. These bubbles generated droplets upon bursting at the air-salt water interface. These droplets were then further dried up and lifted to the top of the column where they were collected as particles. These particles were incubated in a controlled reactor in either dark conditions or under UV-visible light. The difference of alkane content analyzed by GC-MS between the particles exposed to UV or the particles not exposed to UV indicated that up to 20% in mass was lost after 20 min of light exposure. The degradation kinetics varied for each range of alkanes (C16-20, C21-25, C26

  6. NIR-Vis-UV Light-Responsive Actuator Films of Polymer-Dispersed Liquid Crystal/Graphene Oxide Nanocomposites.

    Science.gov (United States)

    Cheng, Zhangxiang; Wang, Tianjie; Li, Xiao; Zhang, Yihe; Yu, Haifeng

    2015-12-16

    To take full advantage of sunlight for photomechanical materials, NIR-vis-UV light-responsive actuator films of polymer-dispersed liquid crystal (PDLC)/graphene oxide (GO) nanocomposites were fabricated. The strategy is based on phase transition of LCs from nematic to isotropic phase induced by combination of photochemical and photothermal processes in the PDLC/GO nanocomposites. Upon mechanical stretching of the film, both topological shape change and mesogenic alignment occurred in the separated LC domains, enabling the film to respond to NIR-vis-UV light. The homodispersed GO flakes act as photoabsorbent and nanoscale heat source to transfer NIR or VIS light into thermal energy, heating the film and photothermally inducing phase transition of LC microdomains. By utilizing photochemical phase transition of LCs upon UV-light irradiation, one azobenzene dye was incorporated into the LC domains, endowing the nanocomposite films with UV-responsive property. Moreover, the light-responsive behaviors can be well-controlled by adjusting the elongation ratio upon mechanical treatment. The NIR-vis-UV light-responsive PDLC/GO nanocomposite films exhibit excellent properties of easy fabrication, low-cost, and good film-forming and mechanical features, promising their numerous applications in the field of soft actuators and optomechanical systems driven directly by sunlight.

  7. Evaluation of anogenital injuries using white and UV-light among adult volunteers following consensual sexual intercourse.

    Science.gov (United States)

    Joki-Erkkilä, Minna; Rainio, Juha; Huhtala, Heini; Salonen, Aki; Karhunen, Pekka J

    2014-09-01

    New clinical forensic examination techniques for sexual assaults have not been introduced over the last few decades. We evaluated the benefit of ultraviolet light compared to white light for detecting minor anogenital injuries and scars, following consensual sexual intercourse among adult volunteers. A prospective study comparing female genital findings utilising white and ultraviolet light. A colposcopy with photographic documentation was used. Personal invitation to healthcare students, hospital employees or acquaintances to volunteer for a gynecological examination, with a focus on clinical forensic aspects. Eighty-eight adult female volunteers were recruited for the study. The examination was performed after consensual intercourse. Age ranged from 20 to 52 years (median 26.5 years). Presence of acute findings and scars in the genital area using white and UV-light. Acute genital injury rate was 14.8% under white light colposcopy and 23.0% using UV light. Submucosal hemorrhages in the genital area were documented significantly better under UV-light than white light (14.9% vs. 6.8%; p=0.016), whereas petechiaes (4.5%) and abrasions (2.3%) were detected using either method. UV-light revealed significantly more often delivery-associated genital scars compared to white light (39.8% vs. 31.8%; p=0.016). Furthermore, 10 out of 31 (33.3%) women had no residual anogenital skin or mucosal surface findings, despite a prior episiotomy or rupture of the vaginal outlet wall during delivery, supporting its enormous ability to heal even after major trauma. UV-light may provide additional value for the evaluation of physical findings in clinical forensic examinations after sexual assault, and is especially useful in detecting otherwise invisible early submucosal hemorrhages and scars. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  8. Acclimation to UV-B radiation and visible light in Lactuca sativa involves up-regulation of photosynthetic performance and orchestration of metabolome-wide responses.

    Science.gov (United States)

    Wargent, J J; Nelson, B C W; McGhie, T K; Barnes, P W

    2015-05-01

    UV-B radiation is often viewed as a source of stress for higher plants. In particular, photosynthetic function has been described as a common target for UV-B impairment; yet as our understanding of UV-B photomorphogenesis increases, there are opportunities to expand the emerging paradigm of regulatory UV response. Lactuca sativa is an important dietary crop species and is often subjected to rapid sunlight exposure at field transfer. Acclimation to UV-B and visible light conditions in L. sativa was dissected using gas exchange and chlorophyll fluorescence measurements, in addition to non-destructive assessments of UV epidermal shielding (SUV ). After UV-B treatment, seedlings were subjected to wide-range metabolomic analysis using liquid chromatography hybrid quadrupole time-of-flight high-resolution mass spectrometry (LC-QTOF-HRMS). During the acclimation period, net photosynthetic rate increased in UV-treated plants, epidermal UV shielding increased in both subsets of plants transferred to the acclimatory conditions (UV+/UV- plants) and Fv /Fm declined slightly in UV+/UV- plants. Metabolomic analysis revealed that a key group of secondary compounds was up-regulated by higher light conditions, yet several of these compounds were elevated further by UV-B radiation. In conclusion, acclimation to UV-B radiation involves co-protection from the effects of visible light, and responses to UV-B radiation at a photosynthetic level may not be consistently viewed as damaging to plant development. © 2014 John Wiley & Sons Ltd.

  9. The effect of UV light on the inactivation of Giardia lamblia and Giardia muris cysts as determined by animal infectivity assay (P-2951-01).

    Science.gov (United States)

    Mofidi, Alexander A; Meyer, Ernest A; Wallis, Peter M; Chou, Connie I; Meyer, Barbara P; Ramalingam, Shivaji; Coffey, Bradley M

    2002-04-01

    This study measured the effect of germicidal ultraviolet (UV) light on Giardia lamblia and Giardia muris cysts, as determined by their infectivity in Mongolian gerbils and CD-1 mice, respectively. Reduction of cyst infectivity due to UV exposure was quantified by applying most probable number techniques. Controlled bench-scale, collimated-beam tests exposed cysts suspended in filtered natural water to light from a low-pressure UV lamp. Both G. lamblia and G. muris cysts showed similar sensitivity to UV light. At 3 mJ/cm2, a dose 10-fold lower than what large-scale UV reactors may be designed to provide, > 2-log10 (99 percent) inactivation was observed. These results, combined with previously published data showing other protozoa and bacteria have similar, high sensitivity to UV light, establish that UV disinfection of drinking water is controlled by viruses which may require over 10-fold more UV dose for the same level of control.

  10. The effect of near-UV light on Na-K-ATPase of the rat lens

    International Nuclear Information System (INIS)

    Torriglia, A.; Zigman, S.

    1988-01-01

    The influence of in vitro near-UV radiation exposure on the physical state of the rat lens and on its membrane-bound Na-K-ATPase activity was investigated. Lens swelling was correlated to the appearance of opacities and the inactivation of the enzyme. The results show a significant decrease in the Na-K-ATPase activity which may be an early change leading to osmotic type cataracts. The dose-effect curves obtained for cortical and epithelial enzymes were different. Since the data do not follow a mono-exponential function, the existence of two forms of Na-K-ATPase in the lens is discussed. (author)

  11. Effect of near-UV light on Na-K-ATPase of the rat lens

    Energy Technology Data Exchange (ETDEWEB)

    Torriglia, A.; Zigman, S.

    1988-06-01

    The influence of in vitro near-UV radiation exposure on the physical state of the rat lens and on its membrane-bound Na-K-ATPase activity was investigated. Lens swelling was correlated to the appearance of opacities and the inactivation of the enzyme. The results show a significant decrease in the Na-K-ATPase activity which may be an early change leading to osmotic type cataracts. The dose-effect curves obtained for cortical and epithelial enzymes were different. Since the data do not follow a mono-exponential function, the existence of two forms of Na-K-ATPase in the lens is discussed.

  12. Use Of Ultra Violet Light (UV-C) To Reduce Possible Microbial Potential In Cold Storage Rooms Loaded With Sweet Potatoes For Exportation

    International Nuclear Information System (INIS)

    Yassin, Sh.M.; El-Neshawy, S.M.; Aly, A.Z.; Abdel Kader, D.A.

    2012-01-01

    Irradiation with Ultraviolet-c (UV-C) light (254 nm) was applied on sweet potatoes (cv. Abees) as well as the major recovered organisms that are accounted as contaminants in either the internal atmosphere or on sweet potato tuber roots loaded in cold storage room set at 17 degree C and 65-70% RH for 3 months. The captured types of microorganisms from either the internal atmosphere of cold storage room or surfaces of sweet potato tuber roots were fungi, yeast and bacteria with the greatest percentage of fungi that recorded 90% and 70%, respectively. The major individuals of recovered fungi were Penicillium spp., Alternaria alternata, Rhizopus stolonifer, Aspergillus spp., Botrytis cinerea, and Fusarium sp. in descending order of their existence percentages. Upon exposure, the internal atmosphere to UV-C light for one, two and three hours inside cold storage room, a significant reduction of the total number of different types of organisms was obtained with the greatest effect for the three hour-exposure time. Exposure of sweet potatoes to UV-C light at three exposure times (1, 2 and 3 hr) and stored in cold rooms for one month caused a reduction of rot percentages upon natural infection conditions with a full reduction (0 %) when irradiated for 3 hr at the same conditions. Rot percentages were decreased as the exposure time increased. Fruit characteristics in terms of tuber root firmness, shrinking and blemishing of irradiated tuber roots were remarkably maintained than which of the non irradiated ones. UV-C light caused a significant increase in phenol contents in tuber root tissue, while a reverse effect in sugar content was detected; such effects were correlated increasingly or decreasingly with the increase of exposure time. The activity of peroxidase, polyphenoloxidase or poly phenylalanine ammonia lyase (PAL) enzymes in irradiated tuber root tissues were significantly enhanced as the exposure time increased

  13. 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.

  14. Applicability of light sources and the inner filter effect in UV/acetylacetone and UV/H{sub 2}O{sub 2} processes

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Bingdang; Yang, Minghui [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023 (China); Yin, Ran [Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong); Zhang, Shujuan, E-mail: sjzhang@nju.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023 (China)

    2017-08-05

    Highlights: • Acetylacetone (AA) could directly use solar irradiation to decolorize dyes. • AA had a wider applicability than H{sub 2}O{sub 2} to a variety of light sources. • The photonic efficiency in the UV/AA process was target-dependent. • An accurate calculation approach for the inner filter effect was developed. - Abstract: Light source is a crucial factor in the application of a photochemical process, which determines the energy efficiency. The performances of acetylacetone (AA) in conversion of aqueous contaminants under irradiation with a low-pressure mercury lamp, a medium-pressure mercury lamp, a xenon lamp, and natural sunlight were investigated and compared with those of H{sub 2}O{sub 2} as reference. In all cases, AA was superior to H{sub 2}O{sub 2} in the degradation of Acid Orange 7. Using combinations of the different light sources with various cut-off and band-pass filters, the spectra responses of the absorbed photons in the UV/AA and UV/H{sub 2}O{sub 2} processes were determined for two colored and two colorless compounds. The photonic efficiency (φ) of the two photochemical processes was found to be target-dependent. A calculation approach for the inner filter effect was developed by taking the obtained φ into account, which provides a more accurate indication of the reaction mechanisms.

  15. UV light induces premature senescence in Akt1-null mouse embryonic fibroblasts by increasing intracellular levels of ROS

    International Nuclear Information System (INIS)

    Jee, Hye Jin; Kim, Hyun-Ju; Kim, Ae Jeong; Bae, Yoe-Sik; Bae, Sun Sik; Yun, Jeanho

    2009-01-01

    Akt/PKB plays a pivotal role in cell survival and proliferation. Previously, we reported that UV-irradiation induces extensive cell death in Akt2 -/- mouse embryonic fibroblasts (MEFs) while Akt1 -/- MEFs show cell cycle arrest. Here, we find that Akt1 -/- MEFs exhibit phenotypic changes characteristics of senescence upon UV-irradiation. An enlarged and flattened morphology, a reduced cell proliferation and an increased senescence-associated β-galactosidase (SA β-gal) staining indicate that Akt1 -/- MEFs undergo premature senescence after UV-irradiation. Restoring Akt1 expression in Akt1 -/- MEFs suppressed SA β-gal activity, indicating that UV-induced senescence is due to the absence of Akt1 function. Notably, levels of ROS were rapidly increased upon UV-irradiation and the ROS scavenger NAC inhibits UV-induced senescence of Akt1 -/- MEFs, suggesting that UV light induces premature senescence in Akt1 -/- MEFs by modulating intracellular levels of ROS. In conjunction with our previous work, this indicates that different isoforms of Akt have distinct function in response to UV-irradiation.

  16. Proposal for Sustainable Dynamic Lighting in Sport Facilities to Decrease Violence among Spectators

    Directory of Open Access Journals (Sweden)

    Raquel Amorim

    2016-12-01

    Full Text Available Violence among spectators at sports events has become a serious problem, not only for its evident impact on safety, but also from the perspective of environmental, cultural, economic and social sustainability. Although it could be considered a purely social problem, some solutions could come from a smart and efficient design and management of the lighting installations. Thus, the management of sports installations requires deep considerations of lighting technology for three reasons: (1 accurate illumination allows the users to achieve their visual task with comfort and safety; (2 the energy consumption of sports facilities can be decreased with an efficient design of the lighting installation; and (3 the lighting impacts some psychological and physiological aspects such as arousal, stress or relaxation which are directly related to violence. In this work, the recent advances on the matter of light sources and non-visual effects of light are deployed within a new proposal of dynamic Light-emitting diode (LED lighting to decrease violence among spectators. Here, sustainable sports facilities are considered from a global perspective where accurate illumination in each zone (court, bleachers, training rooms and surrounding streets plays an important role in violence avoidance.

  17. TiO_2/WO_3 photoactive bilayers in the UV-Vis light region

    International Nuclear Information System (INIS)

    Vasilaki, E.; Vernardou, D.; Kenanakis, G.; Katsarakis, N.; Vamvakaki, M.

    2017-01-01

    In this work, photoactive bilayered films consisting of anatase TiO_2 and monoclinic WO_3 were synthesized by a sol-gel route. Titanium isopropoxide and tungsten hexachloride were used as metal precursors and deposition was achieved by spin-coating on Corning glass substrates. The samples were characterized by X-ray diffraction, photoluminescence, UV-Vis, and Raman spectroscopy, as well as field emission scanning electron microscopy. The prepared immobilized catalysts were tested for their photocatalytic performance by the decolorization of methylene blue in aqueous matrices, under UV-Vis light irradiation. The annealing process influenced the crystallinity of the bilayered films, while the concentration of the tungsten precursor solution and the position of the tungsten trioxide layer further affected their photocatalytic performance. In particular, the photocatalytic performance of the bilayered films was optimized at a concentration of 0.1 M of the WO_3 precursor solution, when deposited as an overlying layer on TiO_2 by two annealing steps (∝76% methylene blue decolorization in 300 min of irradiation versus ∝59% in the case of a bare TiO_2 film). In general, the coupled layer catalysts exhibited superior photoactivity compared to that of bare TiO_2 films with WO_3 acting as an electron trap, resulting, therefore, in a more efficient electron-hole separation and inhibiting their recombination. (orig.)

  18. Photocatalytic Degradation of Methylene Blue under UV Light Irradiation on Prepared Carbonaceous TiO2

    Directory of Open Access Journals (Sweden)

    Zatil Amali Che Ramli

    2014-01-01

    Full Text Available This study involves the investigation of altering the photocatalytic activity of TiO2 using composite materials. Three different forms of modified TiO2, namely, TiO2/activated carbon (AC, TiO2/carbon (C, and TiO2/PANi, were compared. The TiO2/carbon composite was obtained by pyrolysis of TiO2/PANi prepared by in situ polymerization method, while the TiO2/activated carbon (TiO2/AC was obtained after treating TiO2/carbon with 1.0 M KOH solution, followed by calcination at a temperature of 450°C. X-ray powder diffraction (XRD, transmission electron microscopy (TEM, Fourier transform infrared (FTIR, thermogravimetric analysis (TG-DTA, Brunauer-Emmet-Teller (BET, and UV-Vis spectroscopy were used to characterize and evaluate the prepared samples. The specific surface area was determined to be in the following order: TiO2/AC > TiO2/C > TiO2/PANi > TiO2 (179 > 134 > 54 > 9 m2 g−1. The evaluation of photocatalytic performance for the degradation of methylene blue under UV light irradiation was also of the same order, with 98 > 84.7 > 69% conversion rate, which is likely to be attributed to the porosity and synergistic effect in the prepared samples.

  19. A reversible conductivity modulation of azobenzene-based ionic liquids in aqueous solutions using UV/vis light.

    Science.gov (United States)

    Li, Zhiyong; Yuan, Xiaoqing; Feng, Ying; Chen, Yongkui; Zhao, Yuling; Wang, Huiyong; Xu, Qingli; Wang, Jianji

    2018-05-09

    Photo-induced conductivity modulation of stimuli-responsive materials is of great importance from the viewpoint of fundamental research and technology. In this work, 5 new kinds of azobenzene-based photo-responsive ionic liquids were synthesized and characterized, and UV/vis light modulation of their conductivity was investigated in an aqueous solution. The factors affecting the conductivity modulation of the photo-responsive fluids, such as photo-isomerization efficiency, photo-regulation aggregation, concentration and chemical structure of the ionic liquids, were examined systematically. It was found that the conductivity of the ionic liquids in water exhibited a significant increase upon UV light irradiation and the ionic liquids with a shorter alkyl spacer in the cation showed a more remarkable photo-induced conductivity enhancement with a maximum increase of 150%. In addition, the solution conductivity was restored (or very close) to the initial value upon an alternative irradiation with visible light. Thus, the solution conductivity can be modulated using alternative irradiation with UV and visible light. Although the reversible photo-isomerization of the azobenzene group under UV/vis irradiation is the origin of the conductivity modulation, the photo-regulated aggregation of the ionic liquid in water is indispensable for the maximum degree of conductivity modulation because UV irradiation can weaken, even break the aggregated cis-isomers of the ionic liquids in an aqueous solution.

  20. Fenton Process Coupled to Ultrasound and UV Light Irradiation for the Oxidation of a Model Pollutant

    Directory of Open Access Journals (Sweden)

    Karen E. Barrera-Salgado

    2016-01-01

    Full Text Available The Fenton process coupled to photosonolysis (UV light and Us, using Fe2O3 catalyst supported on Al2O3, was used to oxidize a model pollutant like acid green 50 textile dye (AG50. Dye degradation was followed by AG50 concentration decay analyses. It was observed that parameters like iron content on a fixed amount of catalyst supporting material, catalyst annealing temperature, initial dye concentration, and the solution pH influence the overall treatment efficiency. High removal efficiencies of the model pollutant are achieved. The stability and reusability tests of the Fe2O3 catalyst show that the catalyst can be used up to three cycles achieving high discoloration. Thus, this catalyst is highly efficient for the degradation of AG50 in the Fenton process.

  1. Lanthanum doped titania decorated with silver plasmonic nanoparticles with enhanced photocatalytic activity under UV-visible light

    Science.gov (United States)

    Dal'Toé, Adrieli T. O.; Colpani, Gustavo Lopes; Padoin, Natan; Fiori, Márcio Antônio; Soares, Cíntia

    2018-05-01

    Lanthanum doped titanium dioxide decorated with silver plasmonic nanoparticles (Ag-La/TiO2 NPs) materials were prepared using a simple ultrasound-assisted wet impregnation method followed by silver photodeposition. The obtained photocatalysts with different Ag contents were characterized by XRD, FE-SEM, EDX, TEM, BET, XPS, DRS and PL techniques. Moreover, the size distribution of the nanoparticles aggregates was assessed. The characterization analysis revealed that La doping slightly changed the crystalline phase of TiO2, increased the amount of surface hydroxyl groups and interacted with TiO2 nanoparticles via Ti-O-La bond, while Ag photodeposition enhanced the absorption of visible light due to the effects of localized surface plamon resonance and significantly decreased electronic recombination rate by the Schottky junction. Furthermore, the combination of Ag-La induced the formation of oxygen vacancies, which increased the amount of adsorbed surface hydroxyl groups in Ag-La/TiO2. In addition, Ag-La possibly decreased the semiconductor surface energy, which acted positively in the reduction of NPs aggregation. These features along with better textural properties (greater surface areas) played a fundamental role in the enhancement of the photocatalytic activity of Ag-La/TiO2 composites for the decolorization of methylene blue under UV-visible irradiation compared to the mono-metallic (La/TiO2 and Ag/TiO2) modified photocatalysts. Finally, a mechanism for the transfer of charge carriers in Ag-La/TiO2 photocatalyst under UV-visible irradiation was proposed.

  2. UV-visible light photocatalytic properties of NaYF4:(Gd, Si)/TiO2 composites

    Science.gov (United States)

    Mavengere, Shielah; Kim, Jung-Sik

    2018-06-01

    In this study, a new novel composite photocatalyst of NaYF4:(Gd, Si)/TiO2 phosphor has been synthesized by two step method of solution combustion and sol-gel. The photocatalyst powders were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), UV-vis spectroscopy and photoluminescence (PL) spectroscopy. Raman spectroscopy confirmed the anatase TiO2 phase which remarkably increased with existence of yttrium silicate compounds between 800 cm-1 and 900 cm-1. Double-addition of Gd3+-Si4+ ions in NaYF4 host introduced sub-energy band levels with intense absorption in the ultraviolet (UV) light region. Photocatalytic activity was examined by exposing methylene blue (MB) solutions mixed with photocatalyst powders to 254 nm UV-C fluorescent lamp and 200 W visible lights. The UV and visible photocatalytic reactivity of the NaYF4:(Gd, 1% Si)/TiO2 phosphor composites showed enhanced MB degradation efficiency. The coating of NaYF4:(Gd, 1% Si) phosphor with TiO2 nanoparticles creates energy band bending at the phosphor/TiO2 interfaces. Thus, these composites exhibited enhanced absorption of UV/visible light and the separation of electron and hole pairs for efficient photocatalysis.

  3. Optimized treatment conditions for textile wastewater reuse using photocatalytic processes under UV and visible light sources.

    Science.gov (United States)

    Starling, Maria Clara V M; Castro, Luiz Augusto S; Marcelino, Rafaela B P; Leão, Mônica M D; Amorim, Camila C

    2017-03-01

    In this study, photo-Fenton systems using visible light sources with iron and ferrioxalate were tested for the DOC degradation and decolorization of textile wastewater. Textile wastewaters originated after the dyeing stage of dark-colored tissue in the textile industry, and the optimization of treatment processes was studied to produce water suitable for reuse. Dissolved organic carbon, absorbance, turbidity, anionic concentrations, carboxylic acids, and preliminary cost analysis were performed for the proposed treatments. Conventional photo-Fenton process achieved near 99 % DOC degradation rates and complete absorbance removal, and no carboxylic acids were found as products of degradation. Ferrioxalate photo-Fenton system achieved 82 % of DOC degradation and showed complete absorbance removal, and oxalic acid has been detected through HPLC analysis in the treated sample. In contrast, photo-peroxidation with UV light was proved effective only for absorbance removal, with DOC degradation efficiency near 50 %. Treated wastewater was compared with reclaimed water and had a similar quality, indicating that these processes can be effectively applied for textile wastewater reuse. The results of the preliminary cost analysis indicated costs of 0.91 to 1.07 US$ m -3 for the conventional and ferrioxalate photo-Fenton systems, respectively. Graphical Abstract ᅟ.

  4. Development of highly qualified UV-laser light source for rf gun

    International Nuclear Information System (INIS)

    Tomizawa, H.; Dewa, H.; Taniuchi, T.

    2004-01-01

    We have been developing stable and highly qualified UV-laser pulse as a light source of the rf gun for an injector candidate of future light sources. Our gun cavity is a single-cell pillbox, and the copper inner wall is used as a photo cathode. In present status, the short pulse energy stability of laser has been improved down to 1.3∼1.5% (rms; 10pps; 10000 shots) at the third harmonic generation. The long stability depends on the stability of modelocking at oscillator. In this improvement we just passively stabilized the system. We considered environmental controls in clean room to reduce optical damage accidents and constructed a new humidity-controlled clean room in 2003. And we re-installed the total laser system in this room in 2004. The relative humidity of this new clean room at room temperature is in a region of 50∼60 % with a stability of less than 2% (p-p). On the other hand, the ideal spatial and temporal profiles of a shot-by-shot single laser pulse are essential to suppress the emittance growth of the electron beam from a photo-cathode rf gun. This laser-shaping project has been started in two steps since 2002. As the first successful test run in 2002, with a microlens array as a simple spatial shaper, we obtained a minimum emittance value of 2π mm·mrad with a beam energy of 3.1 MeV, holding its charge to 0.1 nC/bunch. In the next test run in 2004, we prepared a deformable mirror for spatial shaping, and a spatial light modulator based on fused-silica plates for temporal shaping. We are applying the both adaptive optics to automatically shape the both spatial and temporal UV-laser profiles with a feedback routine at the same time. We report herein the principle and developing process of our laser beam quality control system. (author)

  5. The Effect of Nitrogen-Doped ATO Nanotubes on Radical Multiplication of Buffer Media by Visible Light Photocatalysis Rather UV

    Directory of Open Access Journals (Sweden)

    Kan-Hung Hu

    2012-01-01

    Full Text Available The use of TiO2 in photodynamic therapy for the treatment of cancer has generally been studied in cultured cancer cells in serum-containing RPMI 1640 medium under visible light application rather than ultraviolet (UV light. An ordered channel array of N-doped anodic titanium dioxide (ATO has been successfully made for visible light application. ATO nanotubes in the anatase form with a length of 10 μm are more effective than nanotubes of 1.8 μm in length as a photocatalyst for radical multiplication in buffer solution by generating hydroxyl radicals and superoxide radical anions under UV-A exposure. Only the N-doped ATO is applicable to visible light photocatalysis for radical multiplication in RPMI 1640+1% FBS and acrylamide, a free radical carrier.

  6. Complementation of a pKM101 derivative that decreases resistance to UV killing but increases susceptibility to mutagenesis

    International Nuclear Information System (INIS)

    Langer, P.J.; Perry, K.L.; Walker, G.C.

    1985-01-01

    The drug resistance plasmid pKM101 makes Escherichia coli resistant to the lethal effects of ultraviolet (UV) irradiation and more susceptible to mutagenesis by a variety of agents. The plasmid operon responsible for increasing mutagenesis has been termed mucAB (Mutagenesis, UV and chemical). The authors have isolated a derivative of pKM101 called pGW1975 which makes cells more sensitive to killing by UV but which retains the ability of pKM101 to increase susceptibility to methyl methanesulfonate (MMS) mutagenesis. pGW1975 increases UV mutagenesis less than pKM101 in a uvrA + strain but more than pKM101 in a uvrA - strain. muc - point and insertion mutants of pKM101 and pGW1975 complement to restore the plasmid-mediated: (i) ability to reactivate UV-irradiated phage, (ii) resistance to killing by UV, and (iii) level of susceptibility to UV mutagenesis. They have identified a 2.0 kb region of pKM101 which is responsible for the complementation and which maps counterclockwise of mucAB. (Auth)

  7. Thermoluminescence properties of Eu and Li co-doped Gd2O3, induced by UV light

    International Nuclear Information System (INIS)

    Hristov, H; Arhangelova, N; Velev, V; Uzunov, N M; Baneva, Y; Nedeva, D; Penev, I; Moschini, G; Rossi, P

    2012-01-01

    For some specific biomedical applications, connected with in-situ measurements of the absorbed dose of ultraviolet (UV) light, we have developed materials, sensitive to the light emission with a wavelength up to 320nm. Thermoluminescence (TL) yield of Gd 2 O 3 , doped with Eu and Li has been analysed with respect to the quantity of Li co-dopant. Lithium has been added as Li 2 CO 3 to a mixture of Gd 2 O 3 with 10 wt% Eu 2 O 3 . Pellets with the mixture have been sintered at a temperature of 1000°C. The kinetic parameters of the phosphors thus obtained have been studied from the TL glow curves after irradiation with UV light. It has been demonstrated that the addition of 16 wt% of Li 2 CO 3 to the Eu-doped Gd 2 O 3 yields a maximum intensity of the peaks at 87°C and at 145°C. Studies on the kinetic parameters as well as the TL properties of Eu-doped Gd 2 O 3 with the addition of 16% of Li 2 CO 3 have been conducted. It has been measured that two of the TL peaks of this phosphor have relatively long fading. Analysis of the TL properties of the phosphors obtained from Gd 2 O 3 , doped with Eu and Li, shows that they possess good sensitivity to the UV emission and could be used as appropriate phosphors for detection and quantitative measurements of UV light.

  8. HISTORY OF AMPHIBIAN DECLINE AND THE PAST, PRESENT AND FUTURE RESEARCH WITH UV LIGHT AND OTHER STRESSORS

    Science.gov (United States)

    This talk is an overview of the history of amphibian decline and the lab research and field monitoring results generated by MED and other agencies. Included are the general field observations leading up to our research initiation, UV-light exposures to the Northern Leopard Frog...

  9. Requirements of blue, UV-A, and UV-B light for normal growth of higher plants, as assessed by actions spectra for growth and related phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, T. [Kobe Women`s Univ., Higashisuma (Japan)

    1994-12-31

    It is very important for experimental purposes, as well as for the practical use of plants when not enough sunlight is available. To grow green higher plants in their normal forms under artificial lighting constructing efficient and economically reasonable lighting systems is not an easy task. One possible approach would be to simulate sunlight in intensity and the radiation spectrum, but its high construction and running costs are not likely to allow its use in practice. Sunlight may be excessive in irradiance in some or all portions of the spectrum. Reducing irradiance and removing unnecessary wavebands might lead to an economically feasible light source. However, removing or reducing a particular waveband from sunlight for testing is not easy. Another approach might be to find the wavebands required for respective aspects of plant growth and to combine them in a proper ratio and intensity. The latter approach seems more practical and economical, and the aim of this Workshop lies in advancing this approach. I summarize our present knowledge on the waveband requirements of higher plants for the regions of blue, UV-A and UV-B.

  10. 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.

  11. 207-nm UV Light-A Promising Tool for Safe Low-Cost Reduction of Surgical Site Infections. II: In-Vivo Safety Studies.

    Science.gov (United States)

    Buonanno, Manuela; Stanislauskas, Milda; Ponnaiya, Brian; Bigelow, Alan W; Randers-Pehrson, Gerhard; Xu, Yanping; Shuryak, Igor; Smilenov, Lubomir; Owens, David M; Brenner, David J

    2016-01-01

    UVC light generated by conventional germicidal lamps is a well-established anti-microbial modality, effective against both bacteria and viruses. However, it is a human health hazard, being both carcinogenic and cataractogenic. Earlier studies showed that single-wavelength far-UVC light (207 nm) generated by excimer lamps kills bacteria without apparent harm to human skin tissue in vitro. The biophysical explanation is that, due to its extremely short range in biological material, 207 nm UV light cannot penetrate the human stratum corneum (the outer dead-cell skin layer, thickness 5-20 μm) nor even the cytoplasm of individual human cells. By contrast, 207 nm UV light can penetrate bacteria and viruses because these cells are physically much smaller. To test the biophysically-based hypothesis that 207 nm UV light is not cytotoxic to exposed mammalian skin in vivo. Hairless mice were exposed to a bactericidal UV fluence of 157 mJ/cm2 delivered by a filtered Kr-Br excimer lamp producing monoenergetic 207-nm UV light, or delivered by a conventional 254-nm UV germicidal lamp. Sham irradiations constituted the negative control. Eight relevant cellular and molecular damage endpoints including epidermal hyperplasia, pre-mutagenic UV-associated DNA lesions, skin inflammation, and normal cell proliferation and differentiation were evaluated in mice dorsal skin harvested 48 h after UV exposure. While conventional germicidal UV (254 nm) exposure produced significant effects for all the studied skin damage endpoints, the same fluence of 207 nm UV light produced results that were not statistically distinguishable from the zero exposure controls. As predicted by biophysical considerations and in agreement with earlier in vitro studies, 207-nm light does not appear to be significantly cytotoxic to mouse skin. These results suggest that excimer-based far-UVC light could potentially be used for its anti-microbial properties, but without the associated hazards to skin of conventional

  12. The UV-light and X-irradiation induced conversion of p-phenoxyphenol in aqueous solution at 250C

    International Nuclear Information System (INIS)

    Ehrl, A.

    1975-01-01

    UV-photolysis and X-radiolysis of p-phenoxyphenol was expected to yield products analogous to those of thyronine, after aromatic structures being equivalent. When exposed to UV-light, p-phenoxyphenol was found being selectively converted into phenylhydroquinone in consequence of intramolecular rearrangement. The reaction heat was estimated applying bond energies to the conversion and comparing the result with differences in the combustion heat of homologous compounds. After X-irradiation, phenylhydroquinone however was not present. Formation of the irradiation products phenol, hydroquinone, p-benzoquinone and pyrocatechol presumed breakage of substrate molecules in consequence of intermolecular interaction with transient water radiolysis species. (orig.) [de

  13. Production of organic compounds in plasmas - A comparison among electric sparks, laser-induced plasmas, and UV light

    Science.gov (United States)

    Scattergood, Thomas W.; Mckay, Christopher P.; Borucki, William J.; Giver, Lawrence P.; Van Ghyseghem, Hilde

    1989-01-01

    In order to ascertain the features of organic compound-production in planetary atmospheres under the effects of plasmas and shocks, various mixtures of N2, CH4, and H2 modeling the atmosphere of Titan were subjected to discrete sparks, laser-induced plasmas, and UV radiation. The experimental results obtained suggest that UV photolysis from the plasma is an important organic compound synthesis process, as confirmed by the photolysis of gas samples that were exposed to the light but not to the shock waves emitted by the sparks. The thermodynamic equilibrium theory is therefore incomplete in the absence of photolysis.

  14. Shining Light on Skin Pigmentation: The Darker and the Brighter Side of Effects of UV Radiation†

    Science.gov (United States)

    Maddodi, Nityanand; Jayanthy, Ashika; Setaluri, Vijayasaradhi

    2012-01-01

    The term barrier function as applied to human skin often connotes the physical properties of this organ that provide protection from its surrounding environment. This term does not generally include skin pigmentation. However, skin pigmentation, which is the result of melanin produced in melanocytes residing the basal layer of the skin and exported to the keratinocytes in the upper layers, serves equally important protective function. Indeed, changes in skin pigmentation are often the most readily recognized indicators of exposure of skin to damaging agents, especially to natural and artificial radiation in the environment. Several recent studies have shed new light on a) the mechanisms of involved in selective effects of subcomponents of UV radiation on human skin pigmentation and b) the interactive influences between keratinocytes and melanocytes, acting as ‘epidermal melanin unit’, that manifest as changes in skin pigmentation in response to exposure to various forms of radiation. This article provides a concise review of our current understanding of the effects of the non-ionizing solar radiation, at cellular and molecular levels, on human skin pigmentation. PMID:22404235

  15. Shining light on skin pigmentation: the darker and the brighter side of effects of UV radiation.

    Science.gov (United States)

    Maddodi, Nityanand; Jayanthy, Ashika; Setaluri, Vijayasaradhi

    2012-01-01

    The term barrier function as applied to human skin often connotes the physical properties of this organ that provides protection from its surrounding environment. This term does not generally include skin pigmentation. However, skin pigmentation, which is the result of melanin produced in melanocytes residing in the basal layer of the skin and exported to the keratinocytes in the upper layers, serves equally important protective function. Indeed, changes in skin pigmentation are often the most readily recognized indicators of exposure of skin to damaging agents, especially to natural and artificial radiation in the environment. Several recent studies have shed new light on (1) the mechanisms involved in selective effects of subcomponents of UV radiation on human skin pigmentation and (2) the interactive influences between keratinocytes and melanocytes, acting as "epidermal melanin unit," that manifest as changes in skin pigmentation in response to exposure to various forms of radiation. This article provides a concise review of our current understanding of the effects of the nonionizing solar radiation, at cellular and molecular levels, on human skin pigmentation. © 2012 Wiley Periodicals, Inc. Photochemistry and Photobiology © 2012 The American Society of Photobiology.

  16. Photocatalytic degradation of p,p'-DDT under UV and visible light using interstitial N-doped TiO₂.

    Science.gov (United States)

    Ananpattarachai, Jirapat; Kajitvichyanukul, Puangrat

    2015-01-01

    1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (or p,p'-DDT) is one of the most persistent pesticides. It is resistant to breakdown in nature and cause the water contamination problem. In this work, a major objective was to demonstrate the application of N-doped TiO2 in degradation and mineralization of the p,p'-DDT under UV and visible light in aqueous solution. The N-doped TiO2 nanopowders were prepared by a simple modified sol-gel procedure using diethanolamine (DEA) as a nitrogen source. The catalyst characteristics were investigated using XRD, SEM, TEM, and XPS. The adsorption and photocatalytic oxidation of p,p'-DDT using the synthesized N-doped TiO2 under UV and visible light were conducted in a batch photocatalytic experiment. The kinetics and p,p'-DDT degradation performance of the N-doped TiO2 were evaluated. Results show that the N-doped TiO2 can degrade p,p'-DDT effectively under both UV and visible lights. The rate constant of the p,p'-DDT degradation under UV light was only 0.0121 min(-1), whereas the rate constant of the p,p'-DDT degradation under visible light was 0.1282 min(-1). Under visible light, the 100% degradation of p,p'-DDT were obtained from N-doped TiO2 catalyst. The reaction rate of p,p'-DDT degradation using N-doped TiO2 under visible light was sixfold higher than that under UV light. According to Langmuir-Hinshelwood model, the adsorption equilibrium constant (K) for the N-doped TiO2 under visible light was 0.03078 L mg(-1), and the apparent reaction rate constant (k) was 1.3941 mg L(-1)-min. Major intermediates detected during the p,p'-DDT degradation were p,p'-DDE, o,p'-DDE, p,p'-DDD and p,p'-DDD. Results from this work can be applied further for the breakdown of p,p'-DDT molecule in the real contaminated water using this technology.

  17. Ultraviolet radiation levels associated with the use of fluorescent general lighting, UV-A and UV-B lamps in the workplace and home

    CERN Document Server

    Whillock, M; MacKinlay, Alistair F; Mundy, S J; Todd, Carl David

    1988-01-01

    A detailed programme of measurements was undertaken by NRPB to determine the ultraviolet irradiance levels likely to be encountered in the workplace and in the home, where fluorescent lighting is used. Assessments have been made of the possible potential risk of the induction of acute effects (photokeratitis, erythema) and of inducing malignant melanoma and non-malignant melanoma skin cancers resulting from exposure to commonly used fluorescent lamps. The optical absorption properties of materials commonly used in diffusers and controllers in commercial and domestic lighting units were also measured. Irradiance data, both weighted (for biological effectiveness) and unweighted, for various lamp types are presented in the report, together with some typical spectral output distributions. The results show that at commonly used illumination levels the UVR emissions from general and special fluorescent lamps presented neither an acute nor a significant chronic hazard. High UV-B emission levels were measured from 'U...

  18. Study of voltage decrease in organic light emitting diodes during the initial stage of lifetime

    Science.gov (United States)

    Cusumano, P.

    2016-02-01

    We report the results of lifetime DC testing at constant current of not-encapsulated organic light emitting diodes (OLEDs) based on Tris (8 idroxyquinoline) aluminum (Alq3) as emitting material. In particular, a voltage decrease during the initial stage of the lifetime test is observed. The cause of this behavior is also discussed, mainly linked to initial Joule self-heating of the device, rising its temperature above room temperature until thermal equilibrium is reached at steady state.

  19. Suppressing effect of antimutagenic flavorings on chromosome aberrations induced by UV-light or X-rays in cultured Chinese hamster cells

    International Nuclear Information System (INIS)

    Sasaki, Yu.F.; Imanishi, Hisako; Watanabe, Mie; Ohta, Toshihiro; Shirasu

    1990-01-01

    Chromosome aberrations induces by UV-light or X-rays were suppressed by the post-treatment with antimutagenic flavorings, such as anisaldehyde, cinnamaldehyde, coumarin, and vanillin. UV- or X-ray-irradiated surviving cells increased in the presence of each flavouring. X-ray-induced breakage-type and exchange-type chromosome aberrations were suppressed by the vanillin treatment in the G 1 phase of the cell cycle and a greater decrease in the number of X-ray-induced chromosome aberrations during G 1 holding was observed in the presence of vanillin. Furthermore, a greater decrease in the number of X-ray-induced DNA single-strand breaks was observed in the presence of vanillin. Treatment with vanillin in the G 2 phase suppressed UV-and X-ray-induced breakage-type but not exchange-type chromosome aberrations. The suppression of breakage-type aberrations was assumed to be due to a modification of the capability of the post-replicational repair of DNA double-strand breaks. (author). 28 refs.; 5 figs.; 6 tabs

  20. Ultraviolet radiation levels associated with the use of fluorescent general lighting, UV-A and UV-B lamps in the workplace and home

    International Nuclear Information System (INIS)

    Whillock, M.; Clark, I.E.; McKinlay, A.F.; Todd, C.D.; Mundy, S.J.

    1988-09-01

    A detailed programme of measurements was undertaken by NRPB to determine the ultraviolet irradiance levels likely to be encountered in the workplace and in the home, where fluorescent lighting is used. Assessments have been made of the possible potential risk of the induction of acute effects (photokeratitis, erythema) and of inducing malignant melanoma and non-malignant melanoma skin cancers resulting from exposure to commonly used fluorescent lamps. The optical absorption properties of materials commonly used in diffusers and controllers in commercial and domestic lighting units were also measured. Irradiance data, both weighted (for biological effectiveness) and unweighted, for various lamp types are presented in the report, together with some typical spectral output distributions. The results show that at commonly used illumination levels the UVR emissions from general and special fluorescent lamps presented neither an acute nor a significant chronic hazard. High UV-B emission levels were measured from 'UV-B' lamps used in this study, and exposure to these lamps would result in acute injury within a short time. Great care should be taken in the use of these lamps, and advice should be provided to workers to ensure safe working conditions and procedures. (author)

  1. Effect of degradative plasmid CAM-OCT on responses of Pseudomonas bacteria to UV light

    International Nuclear Information System (INIS)

    McBeth, D.L.

    1989-01-01

    The effect of plasmid CAM-OCT on responses to UV irradiation was compared in Pseudomonas aeruginosa, in Pseudomonas putida, and in Pseudomonas putida mutants carrying mutations in UV response genes. CAM-OCT substantially increased both survival and mutagenesis in the two species. P. aeruginosa strains without CAM-OCT exhibited much higher UV sensitivity than did P. putida strains. UV-induced mutagenesis of plasmid-free P. putida was easily detected in three different assays (two reversion assays and one forward mutation assay), whereas UV mutagenesis of P. aeruginosa without CAM-OCT was seen only in the forward mutation assay. These results suggest major differences in DNA repair between the two species and highlight the presence of error-prone repair functions on CAM-OCT. A number of P. putida mutants carrying chromosomal mutations affecting either survival or mutagenesis after UV irradiation were isolated, and the effect of CAM-OCT on these mutants was determined. All mutations producing a UV-sensitive phenotype in P. putida were fully suppressed by the plasmid, whereas the plasmid had a more variable effect on mutagenesis mutations, suppressing some and producing no suppression of others. On the basis of the results reported here and results obtained by others with plasmids carrying UV response genes, it appears that CAM-OCT may differ either in regulation or in the number and functions of UV response genes encoded

  2. Retardation of senescence by UV-A light in barley (Hordeum vulgare L.) leaf segments

    International Nuclear Information System (INIS)

    Cuello, J.; Sanchez, M.D.; Sabater, B.

    1994-01-01

    The effects of low intensity (0.9–2.2 W m −2 ) UV-A radiation on barley leaf senescence were investigated. UV-A inhibited chlorophyll loss and caused increases in membrane permeability and chloroplast endopeptidases associated with senescence. The treatment of leaf segments with UV-A changed the type of proteins synthesized by chloroplasts, stimulating the synthesis of some specific polypeptides. It is concluded that the senescence of detached leaves provides an appropriate system for investigating effects of low UV-A intensities which are probably mediated by synthesis of specific proteins. (author)

  3. Colloidal silver nanoparticles prepared by UV-light induced citrate reduction technique for the quantitative detection of uric acid

    Science.gov (United States)

    Maity, Anupam; Panda, Sovan Kumar

    2018-04-01

    Reddish-yellow color colloid consisting of silver nanoparticles (Ag NPs) has been synthesized by reducing aqueous AgNO3 solution by photo-induced citrate reduction technique under UV light. As prepared colloid exhibits single and intense plasmonic absorption peak in the violet region of the visible spectra with the peak centered at 405 nm. The NPs are fine and spherical with diameter ranging from 5 to 10 nm. These colloidal NPs have been used for the quantitative detection of uric acid by UV-VIS spectroscopy. A linear red shifting of the characteristics Plasmonic absorption peak of Ag NPs is observed with uric acid concentration. Uric acid can be detected by UV-VIS spectroscopy down to 5 nM limit using the prepared colloid.

  4. Lifetime Improvement of Organic Light Emitting Diodes using LiF Thin Film and UV Glue Encapsulation

    Science.gov (United States)

    Huang, Jian-Ji; Su, Yan-Kuin; Chang, Ming-Hua; Hsieh, Tsung-Eong; Huang, Bohr-Ran; Wang, Shun-Hsi; Chen, Wen-Ray; Tsai, Yu-Sheng; Hsieh, Huai-En; Liu, Mark O.; Juang, Fuh-Shyang

    2008-07-01

    This work demonstrates the use of lithium fluoride (LiF) as a passivation layer and a newly developed UV glue for encapsulation on the LiF passivation layer to enhance the stability of organic light-emitting devices (OLEDs). Devices with double protective layers showed a 25-fold increase in operational lifetime compared to those without any packaging layers. LiF has a low melting point and insulating characteristics and it can be adapted as both a protective layer and pre-encapsulation film. The newly developed UV glue has a fast curing time of only 6 s and can be directly spin-coated onto the surface of the LiF passivation layer. The LiF thin film plus spin-coated UV glue is a simple packaging method that reduces the fabrication costs of OLEDs.

  5. Removal of gaseous toluene by the combination of photocatalytic oxidation under complex light irradiation of UV and visible light and biological process

    International Nuclear Information System (INIS)

    Wei Zaishan; Sun Jianliang; Xie Zhirong; Liang Mingyan; Chen Shangzhi

    2010-01-01

    Photocatalysis is a promising technology for treatment of gaseous waste; its disadvantages, however, include causing secondary pollution. Biofiltration has been known as an efficient technology for treatment volatile organic compounds (VOCs) at low cost of maintenance, and produces harmless by-products; its disadvantages, include large volume of bioreactor and slow adaptation to fluctuating concentrations in waste gas. A bench scale system integrated with a photocatalytic oxidation and a biofilter unit for the treatment of gases containing toluene was investigated. The integrated system can effectively oxidize toluene with high removal efficiency. The photocatalytic activity of N-TiO 2 /zeolite was evaluated by the decomposition of toluene in air under UV and visible light (VL) illumination. The N-TiO 2 /zeolite has more photocatalytic activity under complex light irradiation of UV and visible light for toluene removal than that of pure TiO 2 /zeolite under UV or visible light irradiation. N-TiO 2 /zeolite was characterized by scanning electron microscopy (SEM), X-ray photoelectron spectrum analysis (XPS), Fourier transform infrared spectroscopy (FT-IR), and as-obtained products were identified by means of gas chromatography/mass spectrometry (GC/MS). Results revealed that the photocatalyst was porous and was high photoactive for mineralizing toluene. The high activity can be attributed to the results of the synergetic effects of strong UV and visible light absorption, surface hydroxyl groups. The photocatalytic degradation reaction of toluene with the N-TiO 2 /zeolite follows Langmuir-Hinshelwood kinetics. Toluene biodegradation rate matches enzymatic oxidation kinetics model.

  6. UV ATTENUATION NEAR CORAL REEFS IN THE FLORIDA KEYS: LIGHT ABSORPTION BY CDOM AND PARTICLES

    Science.gov (United States)

    We have investigated the roles of chromophoric dissolved organic matter (CDOM) and suspended particles in the attenuation of UV radiation in the middle and lower regions of the Florida Keys. Extended exposure to UV radiation, along with elevated sea surface temperatures, impairs...

  7. 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.

  8. Temperature and UV light affect the activity of marine cell-free enzymes

    Directory of Open Access Journals (Sweden)

    B. Thomson

    2017-09-01

    Full Text Available Microbial extracellular enzymatic activity (EEA is the rate-limiting step in the degradation of organic matter in the oceans. These extracellular enzymes exist in two forms: cell-bound, which are attached to the microbial cell wall, and cell-free, which are completely free of the cell. Contrary to previous understanding, cell-free extracellular enzymes make up a substantial proportion of the total marine EEA. Little is known about these abundant cell-free enzymes, including what factors control their activity once they are away from their sites (cells. Experiments were run to assess how cell-free enzymes (excluding microbes respond to ultraviolet radiation (UVR and temperature manipulations, previously suggested as potential control factors for these enzymes. The experiments were done with New Zealand coastal waters and the enzymes studied were alkaline phosphatase (APase, β-glucosidase, (BGase, and leucine aminopeptidase (LAPase. Environmentally relevant UVR (i.e. in situ UVR levels measured at our site reduced cell-free enzyme activities by up to 87 % when compared to controls, likely a consequence of photodegradation. This effect of UVR on cell-free enzymes differed depending on the UVR fraction. Ambient levels of UV radiation were shown to reduce the activity of cell-free enzymes for the first time. Elevated temperatures (15 °C increased the activity of cell-free enzymes by up to 53 % when compared to controls (10 °C, likely by enhancing the catalytic activity of the enzymes. Our results suggest the importance of both UVR and temperature as control mechanisms for cell-free enzymes. Given the projected warming ocean environment and the variable UVR light regime, it is possible that there could be major changes in the cell-free EEA and in the enzymes contribution to organic matter remineralization in the future.

  9. Enhanced mutagenicity of low doses of alkylating agents and UV-light by inhibition of ribonucleotide reductase

    International Nuclear Information System (INIS)

    Jenssen, D.

    1986-01-01

    Monofunctional alkylating agents and UV-light are potent inducers of gene mutations in mammalian cells. Most data on these agent are supporting the idea that 0/sup 6/-alkylguanine is the dominating lesion responsible for the mutations induced by the alkylating agents and thymine-dimers in the case of UV-light. However, little is known about the mutagenic fate of these lesions during the replicative process. This is an essential issue to investigate not the least because of quantitative aspects. By investigating the factors affecting the mutagenic yield of these lesions, they hope to get further information on the mechanisms(s) involved. To study this, a system was applied which involves synchronized V79 Chinese hamster cells and inhibitors of the replication process. By applying hydroxyurea (HU), as inhibitor of the ribonucleotide reductase (RNR) step in DNA synthesis, the effect of nucleotide pool imbalance has been studied at the HGPRT-locus using V79 Chinese hamster cells

  10. Effects of UV light intensity on electrochemical wet etching of SiC for the fabrication of suspended graphene

    Science.gov (United States)

    O, Ryong-Sok; Takamura, Makoto; Furukawa, Kazuaki; Nagase, Masao; Hibino, Hiroki

    2015-03-01

    We report on the effects of UV light intensity on the photo assisted electrochemical wet etching of SiC(0001) underneath an epitaxially grown graphene for the fabrication of suspended structures. The maximum etching rate of SiC(0001) was 2.5 µm/h under UV light irradiation in 1 wt % KOH at a constant current of 0.5 mA/cm2. The successful formation of suspended structures depended on the etching rate of SiC. In the Raman spectra of the suspended structures, we did not observe a significant increase in the intensity of the D peak, which originates from defects in graphene sheets. This is most likely explained by the high quality of the single-crystalline graphene epitaxially grown on SiC.

  11. Carotenoids quench evolution of excited species in epidermis exposed to UV-B (290-320 nm) light

    International Nuclear Information System (INIS)

    Mathews-Roth, M.M.

    1986-01-01

    Reactions involving singlet oxygen and other free radicals have been identified in epidermis containing either exogenous or endogenous photosensitizers, soaked in a singlet oxygen/free radical trap, and then exposed to visible or UV-A (320-400 nm) light. Such reactions can be quenched by the presence of the carotenoid pigments β-carotene and canthaxanthin which accumulate in epidermis after oral administration. It is reported that the carotenoid pigments β-carotene, canthaxanthin and phytoene accumulating in epidermis can also quench to some degree those photochemical reactions involving singlet oxygen and free radicals that occur when epidermis is exposed to the sunburn spectrum of light (UV-B, 290-320 nm). (author)

  12. Report from the NSLS workshop: Sources and applications of high intensity uv-vuv light

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, E.D.; Hastings, J.B. (eds.)

    1990-01-01

    A workshop was held to evaluate sources and applications of high intensity, ultra violet (UV) radiation for biological, chemical, and materials sciences. The proposed sources are a UV free electron laser (FEL) driven by a high brightness linac and undulators in long, straight sections of a specially designed low energy (400 MeV) storage ring. These two distinct types of sources will provide a broad range of scientific opportunities that were discussed in detail during the workshop.

  13. Report from the NSLS workshop: Sources and applications of high intensity uv-vuv light

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, E.D.; Hastings, J.B. [eds.

    1990-12-31

    A workshop was held to evaluate sources and applications of high intensity, ultra violet (UV) radiation for biological, chemical, and materials sciences. The proposed sources are a UV free electron laser (FEL) driven by a high brightness linac and undulators in long, straight sections of a specially designed low energy (400 MeV) storage ring. These two distinct types of sources will provide a broad range of scientific opportunities that were discussed in detail during the workshop.

  14. New horizons for Supercontinuum light sources: from UV to mid-IR

    DEFF Research Database (Denmark)

    Thomsen, Carsten L.; Nielsen, Frederik Donbæk; Johansen, Jeppe

    2013-01-01

    Commercially available supercontinuum sources continue to experience a strong growth in a wide range of industrial and scientific applications. In addition, there is a significant research effort focused on extending the wavelength coverage both towards UV and Mid-IR. Broadband sources covering...... and novel pumping schemes, whereas shifting the spectrum further towards the UV has been based on sophisticated microstructure fiber designs. Here we present our latest developments in tailoring the power and spectral coverage of spatially coherent broadband supercontinuum sources....

  15. Report from the NSLS workshop: Sources and applications of high intensity uv-vuv light

    International Nuclear Information System (INIS)

    Johnson, E.D.; Hastings, J.B.

    1990-01-01

    A workshop was held to evaluate sources and applications of high intensity, ultra violet (UV) radiation for biological, chemical, and materials sciences. The proposed sources are a UV free electron laser (FEL) driven by a high brightness linac and undulators in long, straight sections of a specially designed low energy (400 MeV) storage ring. These two distinct types of sources will provide a broad range of scientific opportunities that were discussed in detail during the workshop

  16. How UV Light Touches the Brain and Endocrine System Through Skin, and Why.

    Science.gov (United States)

    Slominski, Andrzej T; Zmijewski, Michal A; Plonka, Przemyslaw M; Szaflarski, Jerzy P; Paus, Ralf

    2018-05-01

    The skin, a self-regulating protective barrier organ, is empowered with sensory and computing capabilities to counteract the environmental stressors to maintain and restore disrupted cutaneous homeostasis. These complex functions are coordinated by a cutaneous neuro-endocrine system that also communicates in a bidirectional fashion with the central nervous, endocrine, and immune systems, all acting in concert to control body homeostasis. Although UV energy has played an important role in the origin and evolution of life, UV absorption by the skin not only triggers mechanisms that defend skin integrity and regulate global homeostasis but also induces skin pathology (e.g., cancer, aging, autoimmune responses). These effects are secondary to the transduction of UV electromagnetic energy into chemical, hormonal, and neural signals, defined by the nature of the chromophores and tissue compartments receiving specific UV wavelength. UV radiation can upregulate local neuroendocrine axes, with UVB being markedly more efficient than UVA. The locally induced cytokines, corticotropin-releasing hormone, urocortins, proopiomelanocortin-peptides, enkephalins, or others can be released into circulation to exert systemic effects, including activation of the central hypothalamic-pituitary-adrenal axis, opioidogenic effects, and immunosuppression, independent of vitamin D synthesis. Similar effects are seen after exposure of the eyes and skin to UV, through which UVB activates hypothalamic paraventricular and arcuate nuclei and exerts very rapid stimulatory effects on the brain. Thus, UV touches the brain and central neuroendocrine system to reset body homeostasis. This invites multiple therapeutic applications of UV radiation, for example, in the management of autoimmune and mood disorders, addiction, and obesity.

  17. UV decreases the synthesis of free fatty acids and triglycerides in the epidermis of human skin in vivo, contributing to development of skin photoaging.

    Science.gov (United States)

    Kim, Eun Ju; Jin, Xing-Ji; Kim, Yeon Kyung; Oh, In Kyung; Kim, Ji Eun; Park, Chi-Hyun; Chung, Jin Ho

    2010-01-01

    Although fatty acids are known to be important in various skin functions, their roles on photoaging in human skin are poorly understood. We investigated the alteration of lipid metabolism in the epidermis by photoaging and acute UV irradiation in human skin. UV irradiated young volunteers (21-33 years, n=6) and elderly volunteers (70-75 years, n=7) skin samples were obtained by punch biopsy. Then the epidermis was separated from dermis and lipid metabolism was investigated. We observed that the amounts of free fatty acids (FFA) and triglycerides (TG) in the epidermis of photoaged or acutely UV irradiated human skin were significantly decreased. The expressions of genes related to lipid synthesis, including acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), stearoyl-CoA desaturase (SCD), sterol regulatory element binding proteins (SREBPs), and peroxisome proliferator-activated receptors (PPARgamma) were also markedly decreased. To elucidate the significance of these changes of epidermal lipids in human skin, we investigated the effects of TG or various inhibitors for the enzymes involved in TG synthesis on the expression of matrix metalloproteinase-1 (MMP-1) in cultured human epidermal keratinocytes. We demonstrated that triolein (TG) reduced basal and UV-induced MMP-1 mRNA expression. In addition, each inhibitor for various lipid synthesis enzymes, such as TOFA (ACC inhibitor), cerulenin (FAS inhibitor) and trans-10, cis-12-CLA (SCD inhibitor), increased the MMP-1 expression significantly in a dose-dependent manner. We also demonstrated that triolein could inhibit cerulenin-induced MMP-1 expression. Furthermore, topical application of triolein (10%) significantly prevented UV-induced MMP-13, COX-2, and IL-1beta expression in hairless mice. Our results suggest that TG and FFA may play important roles in photoaging of human skin. Copyright 2009 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.

  18. Regulation of the subunit composition of plastidic glutamine synthetase of the wild-type and of the phytochrome-deficient aurea mutant of tomato by blue/UV-A- or by UV-B-light

    International Nuclear Information System (INIS)

    Migge, A.; Carrayol, E.; Hirel, B.; Lohmann, M.; Meya, G.; Becker, T.W.

    1998-01-01

    The photomorphogenetic aurea mutant of tomato severely deficient in spectrophotometrically active phytochromes was used to study the light-regulation of the single-copy nuclear gene encoding plastidic glutamine synthetase (GS-2; EC 6.1.3.2). The de-etiolation of dark-grown aurea mutant seedling cotyledons showed an obligatory dependency on blue light. A limited red light-responsiveness of etiolated aurea cotyledons is, however, retained as seen by the stimulation of both the GS-2 transcript and protein level in the cotyledons of aurea seedlings during growth in red light. The subunits of the octameric GS-2 enzyme were represented by polypeptides with similar electrophoretic mobilities (polypeptides a) in etiolated wild-type or aurea mutant cotyledons. GS-2 proteins with similar apparent molecular masses were also seen in the cotyledons of red light-grown aurea mutant seedlings. In contrast, GS-2 polypeptides with different apparent molecular masses (polypeptides a and b) were detected in the cotyledons of wild-type seedlings grown in red light. This difference indicates that the (post-translational) modification of tomato GS-2 subunit composition is mediated by the photoreceptor phytochrome. The illumination of etiolated wild-type or aurea cotyledons with UV-A- or UV-B-light light resulted in an increase in both the GS-2 transcript and protein level. Following illumination of etiolated wild-type seedlings with UV-A-light, the relative proportion of the GS-2 polypeptides a and b was similar than upon irradiation with blue light but different than after exposure to UV-B- or red light. This result suggests the involvement of a blue/ UV-A-light-specific photoreceptor in the regulation of tomato GS-2 subunit composition. (author)

  19. Repair-deficient xeroderma pigmentosum cells made UV light resistant by fusion with X-ray-inactivated Chinese hamster cells

    International Nuclear Information System (INIS)

    Karentz, D.; Cleaver, J.E.

    1986-01-01

    Xeroderma pigmentosum (XP) is an autosomal recessive human disease, characterized by an extreme sensitivity to sunlight, caused by the inability of cells to repair UV light-induced damage to DNA. Cell fusion was used to transfer fragments of Chinese hamster ovary (CHO) chromosomes into XP cells. The hybrid cells exhibited UV resistance and DNA repair characteristics comparable to those expressed by CHO cells, and their DNA had greater homology with CHO DNA than did the DNA from XP cells. Control experiments consisted of fusion of irradiated and unirradiated XP cells and repeated exposure of unfused XP cells to UV doses used for hybrid selection. These treatments did not result in an increase in UV resistance, repair capability, or homology with CHO DNA. The hybrid cell lines do not, therefore, appear to be XP revertants. The establishment of these stable hybrid cell lines is an initial step toward identifying and cloning CHO DNA repair genes that complement the XP defect in human cells. The method should also be applicable to cloning genes for other diseases, such as ataxia-telangiectasia and Fanconi's anemia

  20. Bcl-2, Bax, and c-Fos expression correlates to RPE cell apoptosis induced by UV-light and daunorubicin

    DEFF Research Database (Denmark)

    Liang, Y G; Jorgensen, A G; Kaestel, C G

    2000-01-01

    PURPOSE. The aim of this study was to determine the role of Bcl-2, Bcl-X L, Bax, and c-Fos in regulation of apoptosis, induced by ultraviolet-light A (UV-A) and daunorubicin (DNR), in retinal pigment epithelium (RPE) cells grown on bovine extracellular matrix (ECM)-coated or uncoated plastic dishes....... METHODS. Apoptosis in confluent RPE cells cultured on ECM-coated or uncoated dishes was induced by UV-A or DNR. Apoptosis was detected by 7-amino-actinomycin D labeling followed by flow cytometry and by terminal deoxy-transferase mediated X-dUTP nick end labeling (TUNEL). Cellular expression of Bcl-2, Bcl......-X L, Bax, and c-Fos was determined by the use of antibodies and flow cytometry, Western blot analysis, and immunocytochemical staining. RESULTS. Both UV-A and DNR induce apoptosis in human RPE cells in vitro. Human fetal RPE cells grown on ECM-coated dishes were significantly more resistant to UV...

  1. Fabrication of silver nanowires and metal oxide composite transparent electrodes and their application in UV light-emitting diodes

    Science.gov (United States)

    Yan, Xingzhen; Ma, Jiangang; Xu, Haiyang; Wang, Chunliang; Liu, Yichun

    2016-08-01

    In this paper, we prepared the silver nanowires (AgNWs)/aluminum-doped zinc oxide (AZO) composite transparent conducting electrodes for n-ZnO/p-GaN heterojunction light emitting-diodes (LEDs) by drop casting AgNW networks and subsequent atomic layer deposition (ALD) of AZO at 150 °C. The contact resistances between AgNWs were dramatically reduced by pre-annealing in the vacuum chamber before the ALD of AZO. In this case, AZO works not only as the conformal passivation layer that protects AgNWs from oxidation, but also as the binding material that improves AgNWs adhesion to substrates. Due to the localized surface plasmons (LSPs) of the AgNWs resonant coupling with the ultraviolet (UV) light emission from the LEDs, a higher UV light extracting efficiency is achieved from LEDs with the AgNWs/AZO composite electrodes in comparison with the conventional AZO electrodes. Additionally, the antireflective nature of random AgNW networks in the composite electrodes caused a broad output light angular distribution, which could be of benefit to certain optoelectronic devices like LEDs and solar cells.

  2. Degradation effects of the active region in UV-C light-emitting diodes

    Science.gov (United States)

    Glaab, Johannes; Haefke, Joscha; Ruschel, Jan; Brendel, Moritz; Rass, Jens; Kolbe, Tim; Knauer, Arne; Weyers, Markus; Einfeldt, Sven; Guttmann, Martin; Kuhn, Christian; Enslin, Johannes; Wernicke, Tim; Kneissl, Michael

    2018-03-01

    An extensive analysis of the degradation characteristics of AlGaN-based ultraviolet light-emitting diodes emitting around 265 nm is presented. The optical power of LEDs stressed at a constant dc current of 100 mA (current density = 67 A/cm2 and heatsink temperature = 20 °C) decreased to about 58% of its initial value after 250 h of operation. The origin of this degradation effect has been studied using capacitance-voltage and photocurrent spectroscopy measurements conducted before and after aging. The overall device capacitance decreased, which indicates a reduction of the net charges within the space-charge region of the pn-junction during operation. In parallel, the photocurrent at excitation energies between 3.8 eV and 4.5 eV and the photocurrent induced by band-to-band absorption in the quantum barriers at 5.25 eV increased during operation. The latter effect can be explained by a reduction of the donor concentration in the active region of the device. This effect could be attributed to the compensation of donors by the activation or diffusion of acceptors, such as magnesium dopants or group-III vacancies, in the pn-junction space-charge region. The results are consistent with the observed reduction in optical power since deep level acceptors can also act as non-radiative recombination centers.

  3. CR-39 (PADC) Reflection and Transmission of Light in the Ultraviolet-Near-Infrared (UV-NIR) Range.

    Science.gov (United States)

    Traynor, Nathan B J; McLauchlin, Christopher; Dodge, Kenneth; McGarrah, James E; Padalino, Stephen J; McCluskey, Michelle; Sangster, T C; McLean, James G

    2018-04-01

    The spectral reflection (specular and diffuse) and transmission of Columbia Resin 39 (CR-39) were measured for incoherent light with wavelengths in the range of 200-2500 nm. These results will be of use for the optical characterization of CR-39, as well as in investigations of the chemical modifications of the polymer caused by ultraviolet (UV) exposure. A Varian Cary 5000 was used to perform spectroscopy on several different thicknesses of CR-39. With proper analysis for the interdependence of reflectance and transmittance, results are consistent across all samples. The reflectivity from each CR-39-air boundary reveals an increase in the index of refraction in the near-UV. Absorption observations are consistent with the Beer-Lambert law. Strong absorption of UV light of wavelength shorter than 350 nm suggests an optical band gap of 3.5 eV, although the standard analysis is not conclusive. Absorption features observed in the near infrared are assigned to molecular vibrations, including some that are new to the literature.

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

    Science.gov (United States)

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

    2011-05-03

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

  5. 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)).

  6. Regulation of the expression of NADP-malic enzyme by UV-B, red and far-red light in maize seedlings

    Directory of Open Access Journals (Sweden)

    P. Casati

    1999-10-01

    Full Text Available The induction of nicotinamide adenine dinucleotide phosphate-malic enzyme (NADP-ME in etiolated maize (Zea mays seedlings by UV-B and UV-A radiation, and different levels of photosynthetically active radiation (PAR, 400-700 nm was investigated by measuring changes in activity, protein quantity and RNA levels as a function of intensity and duration of exposure to the different radiations. Under low levels of PAR, exposure to UV-B radiation but not UV-A radiation for 6 to 24 h caused a marked increase in the enzyme levels similar to that observed under high PAR in the absence of UV-B. UV-B treatment of green leaves following a 12-h dark period also caused an increase in NADP-ME expression. Exposure to UV-B radiation for only 5 min resulted in a rapid increase of the enzyme, followed by a more gradual rise with longer exposure up to 6 h. Low levels of red light for 5 min or 6 h were also effective in inducing NADP-ME activity equivalent to that obtained with UV-B radiation. A 5-min exposure to far-red light following UV-B or red light treatment reversed the induction of NADP-ME, and this effect could be eliminated by further treatment with UV-B or red light. These results indicate that physiological levels of UV-B radiation can have a positive effect on the induction of this photosynthetic enzyme. The reducing power and pyruvate generated by the activity of NADP-ME may be used for respiration, in cellular repair processes and as substrates for fatty acid synthesis required for membrane repair.

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

    International Nuclear Information System (INIS)

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

    2016-01-01

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

  8. Transfer the multiscale texture of crystalline Si onto thin-film micromorph cell by UV nanoimprint for light trapping

    Science.gov (United States)

    Liu, Daiming; Wang, Qingkang; Wang, Qing

    2018-05-01

    Surface texturing is of great significance in light trapping for solar cells. Herein, the multiscale texture, consisting of microscale pyramids and nanoscale porous arrangement, was fabricated on crystalline Si by KOH etching and Ag-assisted HF etching processes and subsequently replicated onto glass with high fidelity by UV nanoimprint method. Light trapping of the multiscale texture was studied by spectral (reflectance, haze ratio) characterizations. Results reveal the multiscale texture provides the broadband reflection reducing, the highlighted light scattering and the additional self-cleaning behaviors. Compared with bare cell, the multiscale textured micromorph cell achieves a 4% relative increase in power conversion efficiency. This surface texturing route paves a promising way for developing low-cost, large-scale and high-efficiency solar applications.

  9. UV Radiation and Visible Light Induce hsp70 Gene Expression in the Antarctic Psychrophilic Ciliate Euplotes focardii.

    Science.gov (United States)

    Fulgentini, Lorenzo; Passini, Valerio; Colombetti, Giuliano; Miceli, Cristina; La Terza, Antonietta; Marangoni, Roberto

    2015-08-01

    The psychrophilic ciliate Euplotes focardii inhabits the shallow marine coastal sediments of Antarctica, where, over millions of years of evolution, it has reached a strict molecular adaptation to such a constant-temperature environment (about -2 °C). This long evolution at sub-zero temperatures has made E. focardii unable to respond to heat stress with the activation of its heat shock protein (hsp) 70 genes. These genes can, however, be expressed in response to other stresses, like the oxidative one, thus indicating that the molecular adaptation has exclusively altered the heat stress signaling pathways, while it has preserved hsp70 gene activation in response to other environmental stressors. Since radiative stress has proved to be affine to oxidative stress in several organisms, we investigated the capability of UV radiation to induce hsp70 transcription. E. focardii cell cultures were exposed to several different irradiation regimes, ranging from visible only to a mixture of visible, UV-A and UV-B. The irradiation values of each spectral band have been set to be comparable with those recorded in a typical Antarctic spring. Using Northern blot analysis, we measured the expression level of hsp70 immediately after irradiation (0-h-labeled samples), 1 h, and 2 h from the end of the irradiation. Surprisingly, our results showed that besides UV radiation, the visible light was also able to induce hsp70 expression in E. focardii. Moreover, spectrophotometric measurements have revealed no detectable endogenous pigments in E. focardii, making it difficult to propose a possible explanation for the visible light induction of its hsp70 genes. Further research is needed to conclusively clarify this point.

  10. Decreased UV-induced DNA repair synthesis in peripheral leukocytes from patients with the nevoid basal cell carcinoma syndrome

    International Nuclear Information System (INIS)

    Ringborg, U.; Lambert, B.; Landergen, J.; Lewensohn, R.

    1981-01-01

    The uv-induced DNA repair synthesis in peripheral leukocytes from 7 patients with the nevoid basal cell carcinoma syndrome was compared to that in peripheral leukocytes from 5 patients with basal cell carcinomas and 39 healthy subjects. A dose response curve was established for each individual, and maximum DNA repair synthesis was used as a measure of the capacity for DNA repair. The patients with the nevoid basal cell carcinoma syndrome had about 25% lower level of maximum DNA repair synthesis as compared to the patients with basal cell carcinomas and control individuals. The possibility that DNA repair mechanisms may be involved in the etiology to the nevoid basal cell carcinoma syndrome is discussed

  11. On red-shift of UV photoluminescence with decreasing size of silicon nanoparticles embedded in SiO2 matrix grown by pulsed laser deposition

    International Nuclear Information System (INIS)

    Chaturvedi, Amita; Joshi, M.P.; Rani, Ekta; Ingale, Alka; Srivastava, A.K.; Kukreja, L.M.

    2014-01-01

    Ensembles of silicon nanoparticles (Si-nps) embedded in SiO 2 matrix were grown by alternate ablation of Si and SiO 2 targets using KrF excimer laser based pulsed laser deposition (PLD). The sizes of Si-nps (mean size ranging from 1–5 nm) were controlled by varying the ablation time of silicon target. Transmission electron microscopy (TEM) along with selected area electron diffraction (SAED) and Raman spectroscopy were used to confirm the growth of silicon nanoparticles, its size variation with growth time and the crystalline quality of the grown nanoparticles. TEM analysis showed that mean size and size distribution of Si-nps increased with increase in the ablation time of Si target. Intense peaks ∼521 cm −1 in Raman analysis showed reasonably good crystalline quality of grown Si-nps. We observed asymmetric broadening of phonon line shapes which also redshift with decreasing size of Si-nps. Photoluminescence (PL) from these samples, obtained at room temperature, was broad band and consisted of three bands in UV and visible range. The intensity of PL band in UV spectral range (peak ∼3.2 eV) was strong compared to visible range bands (peaks ∼2.95 eV and ∼2.55 eV). We observed a small red-shift (∼0.07 eV) of peak position of UV range PL with the decrease in the mean sizes of Si-nps, while there was no appreciable size dependent shift of PL peak positions for other bands in the visible range. The width of UV PL band was also found to increase with decrease of Si-nps mean sizes. Based on the above observations of size dependent redshift of UV range PL band together with the PL lifetimes and PL excitation spectroscopy, the origin of UV PL band is attributed to the direct band transition at the Γ point of Si band structure. Visible range bands were ascribed as defect related transitions. The weak intensities of PL bands ∼2.95 eV and ∼2.55 eV suggested that Si nanoparticles grown by PLD were efficiently capped or passivated by SiO 2 with low density of

  12. The enhanced UV-sensitivity of Escherichia coli uvr A crp strain

    International Nuclear Information System (INIS)

    Skavronskaya, A.G.; Aleshkin, G.I.

    1979-01-01

    Mutations in genes cya and crp do not affect the UV cell sensitivity of Escherichia coli of wild type in relation to repairs of UV-injuries and UV induced mutations yield. Mutations in gene crp (protein defect of catabolitic activator - cap) result in UV sensitivity decrease of E. coli uvrA strain, imperfect as to the first stage of excision repairs not decreasing the quantity of revertants, induced by the UV-light

  13. 207-nm UV light - a promising tool for safe low-cost reduction of surgical site infections. I: in vitro studies.

    Directory of Open Access Journals (Sweden)

    Manuela Buonanno

    Full Text Available BACKGROUND: 0.5% to 10% of clean surgeries result in surgical-site infections, and attempts to reduce this rate have had limited success. Germicidal UV lamps, with a broad wavelength spectrum from 200 to 400 nm are an effective bactericidal option against drug-resistant and drug-sensitive bacteria, but represent a health hazard to patient and staff. By contrast, because of its limited penetration, ~200 nm far-UVC light is predicted to be effective in killing bacteria, but without the human health hazards to skin and eyes associated with conventional germicidal UV exposure. AIMS: The aim of this work was to test the biophysically-based hypothesis that ~200 nm UV light is significantly cytotoxic to bacteria, but minimally cytotoxic or mutagenic to human cells either isolated or within tissues. METHODS: A Kr-Br excimer lamp was used, which produces 207-nm UV light, with a filter to remove higher-wavelength components. Comparisons were made with results from a conventional broad spectrum 254-nm UV germicidal lamp. First, cell inactivation vs. UV fluence data were generated for methicillin-resistant S. aureus (MRSA bacteria and also for normal human fibroblasts. Second, yields of the main UV-associated pre-mutagenic DNA lesions (cyclobutane pyrimidine dimers and 6-4 photoproducts were measured, for both UV radiations incident on 3-D human skin tissue. RESULTS: We found that 207-nm UV light kills MRSA efficiently but, unlike conventional germicidal UV lamps, produces little cell killing in human cells. In a 3-D human skin model, 207-nm UV light produced almost no pre-mutagenic UV-associated DNA lesions, in contrast to significant yields induced by a conventional germicidal UV lamp. CONCLUSIONS: As predicted based on biophysical considerations, 207-nm light kills bacteria efficiently but does not appear to be significantly cytotoxic or mutagenic to human cells. Used appropriately, 207-nm light may have the potential for safely and inexpensively

  14. 207-nm UV light - a promising tool for safe low-cost reduction of surgical site infections. I: in vitro studies.

    Science.gov (United States)

    Buonanno, Manuela; Randers-Pehrson, Gerhard; Bigelow, Alan W; Trivedi, Sheetal; Lowy, Franklin D; Spotnitz, Henry M; Hammer, Scott M; Brenner, David J

    2013-01-01

    0.5% to 10% of clean surgeries result in surgical-site infections, and attempts to reduce this rate have had limited success. Germicidal UV lamps, with a broad wavelength spectrum from 200 to 400 nm are an effective bactericidal option against drug-resistant and drug-sensitive bacteria, but represent a health hazard to patient and staff. By contrast, because of its limited penetration, ~200 nm far-UVC light is predicted to be effective in killing bacteria, but without the human health hazards to skin and eyes associated with conventional germicidal UV exposure. The aim of this work was to test the biophysically-based hypothesis that ~200 nm UV light is significantly cytotoxic to bacteria, but minimally cytotoxic or mutagenic to human cells either isolated or within tissues. A Kr-Br excimer lamp was used, which produces 207-nm UV light, with a filter to remove higher-wavelength components. Comparisons were made with results from a conventional broad spectrum 254-nm UV germicidal lamp. First, cell inactivation vs. UV fluence data were generated for methicillin-resistant S. aureus (MRSA) bacteria and also for normal human fibroblasts. Second, yields of the main UV-associated pre-mutagenic DNA lesions (cyclobutane pyrimidine dimers and 6-4 photoproducts) were measured, for both UV radiations incident on 3-D human skin tissue. We found that 207-nm UV light kills MRSA efficiently but, unlike conventional germicidal UV lamps, produces little cell killing in human cells. In a 3-D human skin model, 207-nm UV light produced almost no pre-mutagenic UV-associated DNA lesions, in contrast to significant yields induced by a conventional germicidal UV lamp. As predicted based on biophysical considerations, 207-nm light kills bacteria efficiently but does not appear to be significantly cytotoxic or mutagenic to human cells. Used appropriately, 207-nm light may have the potential for safely and inexpensively reducing surgical-site infection rates, including those of drug

  15. Rain events decrease boreal peatland net CO2 uptake through reduced light availability.

    Science.gov (United States)

    Nijp, Jelmer J; Limpens, Juul; Metselaar, Klaas; Peichl, Matthias; Nilsson, Mats B; van der Zee, Sjoerd E A T M; Berendse, Frank

    2015-06-01

    Boreal peatlands store large amounts of carbon, reflecting their important role in the global carbon cycle. The short-term exchange and the long-term storage of atmospheric carbon dioxide (CO2 ) in these ecosystems are closely associated with the permanently wet surface conditions and are susceptible to drought. Especially, the single most important peat forming plant genus, Sphagnum, depends heavily on surface wetness for its primary production. Changes in rainfall patterns are expected to affect surface wetness, but how this transient rewetting affects net ecosystem exchange of CO2 (NEE) remains unknown. This study explores how the timing and characteristics of rain events during photosynthetic active periods, that is daytime, affect peatland NEE and whether rain event associated changes in environmental conditions modify this response (e.g. water table, radiation, vapour pressure deficit, temperature). We analysed an 11-year time series of half-hourly eddy covariance and meteorological measurements from Degerö Stormyr, a boreal peatland in northern Sweden. Our results show that daytime rain events systematically decreased the sink strength of peatlands for atmospheric CO2 . The decrease was best explained by rain associated reduction in light, rather than by rain characteristics or drought length. An average daytime growing season rain event reduced net ecosystem CO2 uptake by 0.23-0.54 gC m(-2) . On an annual basis, this reduction of net CO2 uptake corresponds to 24% of the annual net CO2 uptake (NEE) of the study site, equivalent to a 4.4% reduction of gross primary production (GPP) during the growing season. We conclude that reduced light availability associated with rain events is more important in explaining the NEE response to rain events than rain characteristics and changes in water availability. This suggests that peatland CO2 uptake is highly sensitive to changes in cloud cover formation and to altered rainfall regimes, a process hitherto largely

  16. Isoprenoids emission in Stipa tenacissima L.: Photosynthetic control and the effect of UV light

    International Nuclear Information System (INIS)

    Guidolotti, Gabriele; Rey, Ana; Medori, Mauro; Calfapietra, Carlo

    2016-01-01

    Fluxes of CO_2 and isoprenoids were measured for the first time in Stipa tenacissima L (alfa grass), a perennial tussock grass dominant in the driest areas of Europe. In addition, we studied how those fluxes were influenced by environmental conditions, leaf ontogeny and UV radiation and compared emission rates in two contrasting seasons: summer when plants are mostly inactive and autumn, the growing season in this region. Leaf ontogeny significantly affected both photosynthesis and isoprenoids emission. Isoprene emission was positively correlated with photosynthesis, although a low isoprene emission was detected in brown leaves with a net carbon loss. Moreover, leaves with a significant lower photosynthesis emitted only monoterpenes, while at higher photosynthetic rates also isoprene was produced. Ambient UV radiation uncoupled photosynthesis and isoprene emission. It is speculated that alfa grass represent an exception from the general rules governing plant isoprenoid emitters. - Highlights: • Stipa tenacissima L. is a grass emitting either monoterpenes and isoprene. • The emission has reasonable rates even in senescent leaves. • Isoprene emission is positively correlated with CO_2 assimilation. • Ambient UV radiation uncouples photosynthesis and isoprene emission. • Leaves with lower photosynthetic rates emit only monoterpenes. - We proved for the first time that alfa grass emit both isoprene and monoterpene, and we provide some innovative aspects about the UV effect and the behavior of Stipa tenacissima.

  17. UV/Vis and NIR Light-Responsive Spiropyran Self-Assembled Monolayers

    NARCIS (Netherlands)

    Ivashenko, Oleksii; Herpt, Jochem T. van; Feringa, Ben L.; Rudolf, Petra; Browne, Wesley R.

    2013-01-01

    Self-assembled monolayers of a 6-nitro BIPS spiropyran (SP) modified with a disulfide-terminated aliphatic chain were prepared on polycrystalline gold surfaces and characterized by UV/vis absorption, surface-enhanced Raman scattering (SEAS), and X-ray photoelectron spectroscopies (XPS). The SAMs

  18. Isoprenoids emission in Stipa tenacissima L.: Photosynthetic control and the effect of UV light

    Czech Academy of Sciences Publication Activity Database

    Guidolotti, G.; Rey, A.; Medori, M.; Calfapietra, Carlo

    2016-01-01

    Roč. 208, B (2016), s. 336-344 ISSN 0269-7491 R&D Projects: GA MŠk(CZ) LO1415; GA MŠk(CZ) LD13031 Institutional support: RVO:67179843 Keywords : Isoprene * Monoterpene * Alfa grass * UV radiation * Semiarid ecosystems Subject RIV: EH - Ecology, Behaviour Impact factor: 5.099, year: 2016

  19. UV Light Induced Surface Modification of HDPE Films with Bioactive Compounds

    Czech Academy of Sciences Publication Activity Database

    Daniloska, V.; Blazevska-Gilev, J.; Dimova, V.; Fajgar, Radek; Tomovska, R.

    2010-01-01

    Roč. 256, č. 7 (2010), s. 2276-2283 ISSN 0169-4332 Institutional research plan: CEZ:AV0Z40720504 Keywords : surface modification * uv irradiation * benzocaine Subject RIV: CH - Nuclear ; Quantum Chemistry Impact factor: 1.795, year: 2010

  20. Nitrosamine degradation by UV light in post-combustion CO2 capture: effect of solvent matrix

    NARCIS (Netherlands)

    Miguel Mercader, F. de; Voice, A.K.; Trap, H.C.; Goetheer, E.L.V.

    2013-01-01

    Potential production and emission of nitrosamines during post-combustion CO2 capture has drawn some attention due to their toxicity and potential carcinogenicity. One of the possible ways to reduce the concentration of nitrosamines is irradiation of the liquid streams of the capture plant with UV

  1. Effect of nickel doping on the photocatalytic activity of ZnO thin films under UV and visible light

    International Nuclear Information System (INIS)

    Kaneva, Nina V.; Dimitrov, Dimitre T.; Dushkin, Ceco D.

    2011-01-01

    Nanostructured ZnO thin films with different concentrations of Ni 2+ doping (0, 1, 5, 10 and 15 wt.%) are prepared by the sol-gel method for the first time. The thin films are prepared from zinc acetate, 2-methoxyethanol and monoethanolamine on glass substrates by using dip coating method. The films comprise of ZnO nanocrystallites with hexagonal crystal structure, as revealed by X-ray diffraction. The film surface is with characteristic ganglia-like structure as observed by Scanning Electron Microscopy. Furthermore, the Ni-doped films are tested with respect to the photocatalysis in aqueous solutions of malachite green upon UV-light illumination, visible light and in darkness. The initial concentration of malachite green and the amount of catalyst are varied during the experiments. It is found that increasing of the amount of Ni 2+ ions with respect to ZnO generally lowers the photocatalytic activity in comparison with the pure ZnO films. Nevertheless, all films exhibit a substantial activity under both, UV and visible light and in darkness as well, which is promising for the development of new ZnO photocatalysts by the sol-gel method.

  2. Solid-phase photocatalytic degradation of polystyrene plastic with goethite modified by boron under UV-vis light irradiation

    International Nuclear Information System (INIS)

    Liu Guanglong; Zhu Duanwei; Zhou Wenbing; Liao Shuijiao; Cui Jingzhen; Wu Kang; Hamilton, David

    2010-01-01

    A novel photodegradable polyethylene-boron-goethite (PE-B-goethite) composite film was prepared by embedding the boron-doped goethite into the commercial polyethylene. The goethite catalyst was modified by boron in order to improve its photocatalytic efficiency under the ultraviolet and visible light irradiation. Solid-phase photocatalytic degradation of the PE-B-goethite composite film was carried out in an ambient air at room temperature under ultraviolet and visible light irradiation. The properties of composite films were compared with those of the pure PE films and the PE-goethite composite films through performing weight loss monitoring, scanning electron microscope (SEM) analysis, FT-IR spectroscopy and X-ray photoelectron spectroscopy (XPS). The photo-induced degradation of PE-B-goethite composite films was higher than that of the pure PE films and the PE-goethite composite films under the UV-irradiation, while there has been little change under the visible light irradiation. The weight loss of the PE-B-goethite (0.4 wt.%) composite film reached 12.6% under the UV-irradiation for 300 h. The photocatalytic degradation mechanism of the composite films was briefly discussed.

  3. The chalcone synthase multigene family of Petunia hybrida (V30): differential, light-regulated expression during flower development and UV light induction

    International Nuclear Information System (INIS)

    Koes, R.E.; Spelt, C.E.; Mol, J.N.M.

    1989-01-01

    We have analysed the expression of the 8-10 members of the gene family encoding the flavonoid biosynthetic enzyme chalcone synthase (CHS) from Petunia hybrida. During normal plant development only two members of the gene family (CHS-A and CHS-J) are expressed. Their expression is restricted to floral tissues mainly. About 90% of the total CHS mRNA pool is transcribed from CHS-A, wheares CHS-J delivers about 10% in flower corolla, tube and anthers. Expression of CHS-A and CHS-J during flower development is coordinated and (red) light-dependent. In young seedlings and cell suspension cultures expression of CHS-A and CHS-J can be induced with UV light. In addition to CHS-A and CHS-J, expression of another two CHS genes (CHS-B and CHS-G) is induced in young seedlings by UV light, albeit at a low level. In contrast to CHS genes from Leguminoseae, Petunia CHS genes are not inducible by phytopathogen-derived elicitors. Expression of CHS-A and CHS-J is reduced to a similar extent in a regulatory CHS mutant, Petunia hybrida Red Star, suggesting that both genes are regulated by the same trans-acting factors. Comparison of the promoter sequences of CHS-A and CHS-J reveals some striking homologies, which might represent cis-acting regulatory sequences. (author)

  4. Monolithically Integrated Light Feedback Control Circuit for Blue/UV LED Smart Package

    NARCIS (Netherlands)

    Koladouz Esfahani, Z.; Tohidian, M.; van Zeijl, H.W.; Kolahdouz, Mohammadreza; Zhang, G.Q.

    2017-01-01

    Given the performance decay of high-power light-emitting diode (LED) chips over time and package condition changes, having a reliable output light for sensitive applications is a point of concern. In this study, a light feedback control circuit, including blue-selective photodiodes, for

  5. 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.

  6. Growth under visible light increases conidia and mucilage production and tolerance to UV-B radiation in the plant pathogenic fungus Colletotrichum acutatum.

    Science.gov (United States)

    de Menezes, Henrique D; Massola, Nelson S; Flint, Stephan D; Silva, Geraldo J; Bachmann, Luciano; Rangel, Drauzio E N; Braga, Gilberto U L

    2015-01-01

    Light conditions can influence fungal development. Some spectral wavebands can induce conidial production, whereas others can kill the conidia, reducing the population size and limiting dispersal. The plant pathogenic fungus Colletotrichum acutatum causes anthracnose in several crops. During the asexual stage on the host plant, Colletototrichum produces acervuli with abundant mucilage-embedded conidia. These conidia are responsible for fungal dispersal and host infection. This study examined the effect of visible light during C. acutatum growth on the production of conidia and mucilage and also on the UV tolerance of these conidia. Conidial tolerance to an environmentally realistic UV irradiance was determined both in conidia surrounded by mucilage on sporulating colonies and in conidial suspension. Exposures to visible light during fungal growth increased production of conidia and mucilage as well as conidial tolerance to UV. Colonies exposed to light produced 1.7 times more conidia than colonies grown in continuous darkness. The UV tolerances of conidia produced under light were at least two times higher than conidia produced in the dark. Conidia embedded in the mucilage on sporulating colonies were more tolerant of UV than conidia in suspension that were washed free of mucilage. Conidial tolerance to UV radiation varied among five selected isolates. © 2014 The American Society of Photobiology.

  7. The repair of low dose UV light-induced damage to human skin DNA in condition of trace amount Mg 2+

    Science.gov (United States)

    Gao, Fang; Guo, Zhouyi; Zheng, Changchun; Wang, Rui; Liu, Zhiming; Meng, Pei; Zhai, Juan

    2008-12-01

    Ultraviolet light-induced damage to human skin DNA was widely investigated. The primary mechanism of this damage contributed to form cyclobutane pyrimidine dimmers (CPDs). Although the distribution of UV light-induced CPDs within a defined sequence is similar, the damage in cellular environment which shields the nuclear DNA was higher than that in organism in apparent dose. So we use low UVB light as main study agent. Low dose UV-irradiated HDF-a cells (Human Dermal Fibroblasts-adult cells) which is weaker than epidermic cells were cultured with DMEM at different trace amount of Mg2+ (0mmol/L , 0.1mmol/L , 0.2mmol/L, 0.4mmol/L, 0.8mmol/L, 1.2mmol/L) free-serum DMEM and the repair of DNA strands injured were observed. Treat these cells with DNA strand breaks detection, photoproducts detection and the repair of photoproducts detection. Then quantitate the role of trace amount Mg2+ in repair of UV light-induced damage to human skin. The experiment results indicated that epidermic cells have capability of resistance to UV-radiation at a certain extent. And Mg2+ can regulate the UV-induced damage repair and relative vitality. It can offer a rationale and experiment data to relieve UV light-induced skin disease.

  8. White light emission from Tm3+/Dy3+ co-doped oxyfluoride germanate glasses under UV light excitation

    International Nuclear Information System (INIS)

    Lakshminarayana, G.; Yang Hucheng; Qiu Jianrong

    2009-01-01

    In this paper, we report on the absorption and photoluminescence properties of Tm 3+ /Dy 3+ ions co-doped oxyfluoride germanate glasses for white light emission. The X-ray diffraction (XRD) and differential thermal analysis (DTA) profiles of the host glass have been carried out to confirm its structure and thermal stability. From the measured absorption spectra, Judd-Ofelt (J-O) intensity parameters (Ω 2 , Ω 4 and Ω 6 ) have been evaluated for Tm 3+ and Dy 3+ ions. A combination of blue, yellow and red emissions has emerged in these glasses, which allows the observation of bright white light when the glasses are excited by the ultraviolet light. The white light luminescence colour could be changed by varying the excitation wavelength. Also, various colours of luminescence, including white light, can be easily tuned by adjusting the concentrations of Tm 3+ or Dy 3+ ions in the co-doped glasses. Concentration quenching effect was also investigated and possible energy transfer mechanism from Dy 3+ →Tm 3+ ions was explained which is also confirmed by the decay lifetime measurements. - Graphical Abstract: A combination of blue, yellow and red emissions has emerged from Tm 3+ /Dy 3+ co-doped glasses, which allows the observation of bright white light and makes them as excellent candidates applicable in the solid-state multi-colour three-dimensional display.

  9. Salt-embedded carbon nanodots as a UV and thermal stable fluorophore for light-emitting diodes

    International Nuclear Information System (INIS)

    Kim, Tak H.; Wang, Fu; McCormick, Paul; Wang, Lianzhou; Brown, Chris; Li, Qin

    2014-01-01

    UV and thermal stable, photoluminescent carbon dots (CDs) prepared by embedding CDs in ionic salt crystals such as NaCl, KCl, KBr are demonstrated. The salt crystal embedding matrix does not interfere with CDs strong emission, and provides effective protection to CDs from the environment. The degradation of 20% of the initial luminescence intensity of salt-encapsulated CDs (S-CDs) is 15 times slower under UV and 6 times slower under heat compared to that of CDs in silica matrix. We also demonstrate that the S-CDs can be applied as a color-converting phosphor for typical GaN UV light emitting diodes (LEDs) with significant improvements in stability as well as processability. - Highlights: • Carbon dots can be uniformly embedded in ionic salt crystals via crystallization. • Salt crystals provide oxygen-tight matrices for protecting carbon dots from degradations. • Salt-embedded carbon dots can be applied as a stable color-converting phosphor in LEDs

  10. Salt-embedded carbon nanodots as a UV and thermal stable fluorophore for light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tak H. [Queensland Micro- and Nano-Technology Centre, Griffith University, Nathan, QLD 4111 (Australia); Environmental Engineering, Griffith University, QLD 4111 (Australia); Wang, Fu [Institute of Physiology, University of Freiburg, Hermann-Herder-Street 7, 79104 Freiburg (Germany); McCormick, Paul [School of Mechanical and Chemical Engineering, The University of Western Australia, WA 2009 (Australia); Wang, Lianzhou [School of Chemical Engineering, The University of Queensland, QLD 4072 (Australia); Brown, Chris [Queensland Micro- and Nano-Technology Centre, Griffith University, Nathan, QLD 4111 (Australia); Li, Qin, E-mail: qin.li@griffith.edu.au [Queensland Micro- and Nano-Technology Centre, Griffith University, Nathan, QLD 4111 (Australia); Environmental Engineering, Griffith University, QLD 4111 (Australia)

    2014-10-15

    UV and thermal stable, photoluminescent carbon dots (CDs) prepared by embedding CDs in ionic salt crystals such as NaCl, KCl, KBr are demonstrated. The salt crystal embedding matrix does not interfere with CDs strong emission, and provides effective protection to CDs from the environment. The degradation of 20% of the initial luminescence intensity of salt-encapsulated CDs (S-CDs) is 15 times slower under UV and 6 times slower under heat compared to that of CDs in silica matrix. We also demonstrate that the S-CDs can be applied as a color-converting phosphor for typical GaN UV light emitting diodes (LEDs) with significant improvements in stability as well as processability. - Highlights: • Carbon dots can be uniformly embedded in ionic salt crystals via crystallization. • Salt crystals provide oxygen-tight matrices for protecting carbon dots from degradations. • Salt-embedded carbon dots can be applied as a stable color-converting phosphor in LEDs.

  11. Sacrificial hydrogen generation from aqueous triethanolamine with Eosin Y-sensitized Pt/TiO2 photocatalyst in UV, visible and solar light irradiation.

    Science.gov (United States)

    Chowdhury, Pankaj; Gomaa, Hassan; Ray, Ajay K

    2015-02-01

    In this paper, we have studied Eosin Y-sensitized sacrificial hydrogen generation with triethanolamine as electron donor in UV, visible, and solar light irradiation. Aeroxide TiO2 was loaded with platinum metal via solar photo-deposition method to reduce the electron hole recombination process. Photocatalytic sacrificial hydrogen generation was influenced by several factors such as platinum loading (wt%) on TiO2, solution pH, Eosin Y to Pt/TiO2 mass ratio, triethanolamine concentration, and light (UV, visible and solar) intensities. Detailed reaction mechanisms in visible and solar light irradiation were established. Oxidation of triethanolamine and formaldehyde formation was correlated with hydrogen generation in both visible and solar lights. Hydrogen generation kinetics followed a Langmuir-type isotherm with reaction rate constant and adsorption constant of 6.77×10(-6) mol min(-1) and 14.45 M(-1), respectively. Sacrificial hydrogen generation and charge recombination processes were studied as a function of light intensities. Apparent quantum yields (QYs) were compared for UV, visible, and solar light at four different light intensities. Highest QYs were attained at lower light intensity because of trivial charge recombination. At 30 mW cm(-2) we achieved QYs of 10.82%, 12.23% and 11.33% in UV, visible and solar light respectively. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Apparatus and method for treating pollutants in a gas using hydrogen peroxide and UV light

    Science.gov (United States)

    Cooper, Charles David (Inventor); Clausen, Christian Anthony (Inventor)

    2005-01-01

    An apparatus for treating pollutants in a gas may include a source of hydrogen peroxide, and a treatment injector for creating and injecting dissociated hydrogen peroxide into the flow of gas. The treatment injector may further include an injector housing having an inlet, an outlet, and a hollow interior extending therebetween. The inlet may be connected in fluid communication with the source of hydrogen peroxide so that hydrogen peroxide flows through the hollow interior and toward the outlet. At least one ultraviolet (UV) lamp may be positioned within the hollow interior of the injector housing. The at least one UV lamp may dissociate the hydrogen peroxide flowing through the tube. The dissociated hydrogen peroxide may be injected into the flow of gas from the outlet for treating pollutants, such as nitrogen oxides.

  13. 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

  14. Alteration of five organic compounds by glow discharge plasma and UV light under simulated Mars conditions

    Science.gov (United States)

    Hintze, Paul E.; Buhler, Charles R.; Schuerger, Andrew C.; Calle, Luz M.; Calle, Carlos I.

    2010-08-01

    The Viking missions to Mars failed to detect any organic material in regolith samples. Since then, several removal mechanisms of organic material have been proposed. Two of these proposed methods are removal due to exposure to plasmas created in dust devils and exposure to UV irradiation. The experiments presented here were performed to identify similarities between the two potential removal mechanisms and to identify any compounds produced from these mechanisms that would have been difficult for the Viking instruments to detect. Five organic compounds, phenanthrene, octadecane, octadecanoic acid, decanophenone and benzoic acid, were exposed to a glow discharge plasma created in simulated martian atmospheres as might be present in dust devils, and to UV irradiation similar to that found at the surface of Mars. Glow discharge exposure was carried out in a chamber with 6.9 mbar pressure of a Mars like gas composed mostly of carbon dioxide. The plasma was characterized using emission spectroscopy and found to contain cations and excited neutral species including carbon dioxide, carbon monoxide, and nitrogen. UV irradiation experiments were performed in a Mars chamber which simulates the temperature, pressure, atmospheric composition, and UV fluence rates of equatorial Mars. The non-volatile residues left after each exposure were characterized by mass loss, infrared spectroscopy and high resolution mass spectrometry. Oxidized, higher molecular weight versions of the parent compounds containing carbonyl, hydroxyl and alkenyl functional groups were identified. The presence of these oxidized compounds suggests that searches for organic material in soils on Mars use instrumentation suitable for detection of compounds which contain the above functional groups. Discussions of possible reaction mechanisms are given.

  15. Enhanced UV light detection using a p-terphenyl wavelength shifter

    Science.gov (United States)

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

    2017-10-01

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

  16. Effectiveness of UV-C light irradiation on disinfection of an eSOS(®) smart toilet evaluated in a temporary settlement in the Philippines.

    Science.gov (United States)

    Zakaria, Fiona; Harelimana, Bertin; Ćurko, Josip; van de Vossenberg, Jack; Garcia, Hector A; Hooijmans, Christine Maria; Brdjanovic, Damir

    2016-01-01

    Ultraviolet germicidal (short wavelength UV-C) light was studied as surface disinfectant in an Emergency Sanitation Operation System(®) smart toilet to aid to the work of manual cleaning. The UV-C light was installed and regulated as a self-cleaning feature of the toilet, which automatically irradiate after each toilet use. Two experimental phases were conducted i.e. preparatory phase consists of tests under laboratory conditions and field testing phase. The laboratory UV test indicated that irradiation for 10 min with medium-low intensity of 0.15-0.4 W/m(2) could achieve 6.5 log removal of Escherichia coli. Field testing of the toilet under real usage found that UV-C irradiation was capable to inactivate total coliform at toilet surfaces within 167-cm distance from the UV-C lamp (UV-C dose between 1.88 and 2.74 mW). UV-C irradiation is most effective with the support of effective manual cleaning. Application of UV-C for surface disinfection in emergency toilets could potentially reduce public health risks.

  17. Absorbance detector for high performance liquid chromatography based on a deep-UV light-emitting diode at 235nm.

    Science.gov (United States)

    da Silveira Petruci, João Flavio; Liebetanz, Michael G; Cardoso, Arnaldo Alves; Hauser, Peter C

    2017-08-25

    In this communication, we describe a flow-through optical absorption detector for HPLC using for the first time a deep-UV light-emitting diode with an emission band at 235nm as light source. The detector is also comprised of a UV-sensitive photodiode positioned to enable measurement of radiation through a flow-through cuvette with round aperture of 1mm diameter and optical path length of 10mm, and a second one positioned as reference photodiode; a beam splitter and a power supply. The absorbance was measured and related to the analyte concentration by emulating the Lambert-Beer law with a log-ratio amplifier circuitry. This detector showed noise levels of 0.30mAU, which is comparable with our previous LED-based detectors employing LEDs at 280 and 255nm. The detector was coupled to a HPLC system and successfully evaluated for the determination of the anti-diabetic drugs pioglitazone and glimepiride in an isocratic separation and the benzodiazepines flurazepam, oxazepam and clobazam in a gradient elution. Good linearities (r>0.99), a precision better than 0.85% and limits of detection at sub-ppm levels were achieved. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Using resonance light scattering and UV/vis absorption spectroscopy to study the interaction between gliclazide and bovine serum albumin.

    Science.gov (United States)

    Zhang, Qiu-Ju; Liu, Bao-Sheng; Li, Gai-Xia; Han, Rong

    2016-08-01

    At different temperatures (298, 310 and 318 K), the interaction between gliclazide and bovine serum albumin (BSA) was investigated using fluorescence quenching spectroscopy, resonance light scattering spectroscopy and UV/vis absorption spectroscopy. The first method studied changes in the fluorescence of BSA on addition of gliclazide, and the latter two methods studied the spectral change in gliclazide while BSA was being added. The results indicated that the quenching mechanism between BSA and gliclazide was static. The binding constant (Ka ), number of binding sites (n), thermodynamic parameters, binding forces and Hill's coefficient were calculated at three temperatures. Values for the binding constant obtained using resonance light scattering and UV/vis absorption spectroscopy were much greater than those obtained from fluorescence quenching spectroscopy, indicating that methods monitoring gliclazide were more accurate and reasonable. In addition, the results suggest that other residues are involved in the reaction and the mode 'point to surface' existed in the interaction between BSA and gliclazide. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  19. Structural characteristics and UV-light enhanced gas sensitivity of La-doped ZnO nanoparticles

    International Nuclear Information System (INIS)

    Ge Chunqiao; Xie Changsheng; Hu Mulin; Gui Yanghai; Bai Zikui; Zeng Dawen

    2007-01-01

    La-doped ZnO nanoparticles were synthesized by sol-gel method starting from zinc acetate dihydrate, lanthanum sesquioxide, alcohol and nitric acid. The crystal structure and morphology of the nanoparticles were characterized by XRD, FESEM, respectively. The thermal decomposition behavior of the the ZnO-based xerogel was detected by TG-DSC. The results show that as-prepared nanoparticles with the hexagonal wurtzite contain the adsorbed water and some organic compounds below 300 o C, which is the key to the calcinations of the ZnO-based xerogel. Pure ZnO and La-doped ZnO thick film sensors were prepared and tested for specific sensitivity to alcohol and benzene with (and without) UV-light excitation. Among all, 10 at.%La-ZnO-based sensors are significantly sensitive to 100 ppm alcohol and 100 ppm benzene. There is an obvious enhancement of the gas-sensing performances with UV-light excitation. That is, the sensitivity to 100 ppm benzene rises twice. The observed sensitivity to alcohol and benzene could be explained with the surface adsorption theory and the conduction-band theory

  20. Luminescence properties of Ca2 Ga2 SiO7 :RE phosphors for UV white-light-emitting diodes.

    Science.gov (United States)

    Jiao, Mengmeng; Lv, Wenzhen; Lü, Wei; Zhao, Qi; Shao, Baiqi; You, Hongpeng

    2015-03-16

    A series of Eu(2+) -, Ce(3+) -, and Tb(3+) -doped Ca2 Ga2 SiO7 phosphors is synthesized by using a high-temperature solid-state reaction. The powder X-ray diffraction and structure refinement data indicate that our prepared phosphors are single phased and the phosphor crystalizes in a tetrahedral system with the ${P\\bar 42m}$ (113) space group. The Eu(2+) - and Ce(3+) -doped phosphors both have broad excitation bands, which match well with the UV light-emitting diodes chips. Under irradiation of λ=350 nm, Ca2 Ga2 SiO7 :Eu(2+) and Ca2 Ga2 SiO7 :Ce(3+) , Li(+) have green and blue emissions, respectively. Luminescence of Ca2 Ga2 SiO7 :Tb(3+) , Li(+) phosphor varies with the different Tb(3+) contents. The thermal stability and energy-migration mechanism of Ca2 Ga2 SiO7 :Eu(2+) are also studied. The investigation results indicate that the prepared Ca2 Ga2 SiO7 :Eu(2+) and Ca2 Ga2 SiO7 :Ce(3+) , Li(+) samples show potential as green and blue phosphors, respectively, for UV-excited white-light-emitting diodes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Energy transfer and colour tunability in UV light induced Tm3+/Tb3+/Eu3+: ZnB glasses generating white light emission.

    Science.gov (United States)

    Naresh, V; Gupta, Kiran; Parthasaradhi Reddy, C; Ham, Byoung S

    2017-03-15

    A promising energy transfer (Tm 3+ →Tb 3+ →Eu 3+ ) approach is brought forward to generate white light emission under ultraviolet (UV) light excitation for solid state lightening. Tm 3+ /Tb 3+ /Eu 3+ ions are combinedly doped in zinc borate glass system in view of understanding energy transfer process resulting in white light emission. Zinc borate (host) glass displayed optical and luminescence properties due to formation of Zn(II) x -[O(-II)] y centres in the ZnB glass matrix. At 360nm (UV) excitation, triply doped Tm 3+ /Tb 3+ /Eu 3+ : ZnB glasses simultaneously shown their characteristic emission bands in blue (454nm: 1 D 2 → 3 F 4 ), green (547nm: 5 D 4 → 7 F 5 ) and red (616nm: 5 D 0 → 7 F 2 ) regions. In triple ions doped glasses, energy transfer dynamics is discussed in terms of Forster-Dexter theory, excitation & emission profiles, lifetime curves and from partial energy level diagram of three ions. The role of Tb 3+ in ET from Tm 3+ →Eu 3+ was discussed using branch model. From emission decay analysis, energy transfer probability (P) and efficiency (η) were evaluated. Colour tunability from blue to white on varying (Tb 3+ , Eu 3+ ) content is demonstrated from Commission Internationale de L'Eclairage (CIE) chromaticity coordinates. Based on chromaticity coordinates, other colour related parameters like correlated colour temperature (CCT) and colour purity are also computed for the studied glass samples. An appropriate blending of such combination of rare earth ions could show better suitability as potential candidates in achieving multi-colour and warm/cold white light emission for white LEDs application in the field of solid state lightening. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Fabrication of white light-emitting diodes based on UV light-emitting diodes with conjugated polymers-(CdSe/ZnS) quantum dots as hybrid phosphors.

    Science.gov (United States)

    Jung, Hyunchul; Chung, Wonkeun; Lee, Chang Hun; Kim, Sung Hyun

    2012-07-01

    White light-emitting diodes (LEDs) were fabricated using GaN-based 380-nm UV LEDs precoated with the composite of blue-emitting polymer (poly[(9,9-dihexylfluorenyl-2,7-diyl)-alt-co-(2-methoxy-5-{2-ethylhexyloxy)-1 ,4-phenylene)]), yellow green-emitting polymer (poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-{2,1',3}-thiadiazole)]), and 605-nm red-emitting quantum dots (QDs). CdSe cores were obtained by solvothermal route using CdO, Se precursors and ZnS shells were synthesized by using diethylzinc, and hexamethyldisilathiane precursors. The optical properties of CdSe/ZnS QDs were characterized by UV-visible and photoluminescence (PL) spectra. The structural data and composition of the QDs were transmission electron microscopy (TEM), and EDX technique. The quantum yield and size of the QDs were 58.7% and about 6.7 nm, respectively. Three-band white light was generated by hybridizing blue (430 nm), green (535 nm), and red (605 nm) emission. The color-rendering index (CRI) of the device was extremely improved by introducing the QDs. The CIE-1931 chromaticity coordinate, color temperature, and CRI of a white LED at 20 mA were (0.379, 0.368), 3969 K, and 90, respectively.

  3. All-photonic drying and sintering process via flash white light combined with deep-UV and near-infrared irradiation for highly conductive copper nano-ink

    Science.gov (United States)

    Hwang, Hyun-Jun; Oh, Kyung-Hwan; Kim, Hak-Sung

    2016-01-01

    We developed an ultra-high speed photonic sintering method involving flash white light (FWL) combined with near infrared (NIR) and deep UV light irradiation to produce highly conductive copper nano-ink film. Flash white light irradiation energy and the power of NIR/deep UV were optimized to obtain high conductivity Cu films. Several microscopic and spectroscopic characterization techniques such as scanning electron microscopy (SEM), a x-ray diffraction (XRD), and Fourier-transform infrared (FT-IR) spectroscopy were employed to characterize the Cu nano-films. Optimally sintered Cu nano-ink films produced using a deep UV-assisted flash white light sintering technique had the lowest resistivity (7.62 μΩ·cm), which was only 4.5-fold higher than that of bulk Cu film (1.68 μΩ•cm). PMID:26806215

  4. 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

  5. Can narrow-bandwidth light from UV-A to green alter secondary plant metabolism and increase Brassica plant defenses against aphids?

    Science.gov (United States)

    Neugart, Susanne; Schreiner, Monika; Wu, Sasa; Poehling, Hans-Michael

    2017-01-01

    Light of different wavelengths is essential for plant growth and development. Short-wavelength radiation such as UV can shift the composition of flavonoids, glucosinolates, and other plant metabolites responsible for enhanced defense against certain herbivorous insects. The intensity of light-induced, metabolite-based resistance is plant- and insect species-specific and depends on herbivore feeding guild and specialization. The increasing use of light-emitting diodes (LEDs) in horticultural plant production systems in protected environments enables the creation of tailor-made light scenarios for improved plant cultivation and induced defense against herbivorous insects. In this study, broccoli (Brassica oleracea var. italica) plants were grown in a climate chamber under broad spectra photosynthetic active radiation (PAR) and were additionally treated with the following narrow-bandwidth light generated with LEDs: UV-A (365 nm), violet (420 nm), blue (470 nm), or green (515 nm). We determined the influence of narrow-bandwidth light on broccoli plant growth, secondary plant metabolism (flavonol glycosides and glucosinolates), and plant-mediated light effects on the performance and behavior of the specialized cabbage aphid Brevicoryne brassicae. Green light increased plant height more than UV-A, violet, or blue LED treatments. Among flavonol glycosides, specific quercetin and kaempferol glycosides were increased under violet light. The concentration of 3-indolylmethyl glucosinolate in plants was increased by UV-A treatment. B. brassicae performance was not influenced by the different light qualities, but in host-choice tests, B. brassicae preferred previously blue-illuminated plants (but not UV-A-, violet-, or green-illuminated plants) over control plants. PMID:29190278

  6. Can narrow-bandwidth light from UV-A to green alter secondary plant metabolism and increase Brassica plant defenses against aphids?

    Directory of Open Access Journals (Sweden)

    Ole Rechner

    Full Text Available Light of different wavelengths is essential for plant growth and development. Short-wavelength radiation such as UV can shift the composition of flavonoids, glucosinolates, and other plant metabolites responsible for enhanced defense against certain herbivorous insects. The intensity of light-induced, metabolite-based resistance is plant- and insect species-specific and depends on herbivore feeding guild and specialization. The increasing use of light-emitting diodes (LEDs in horticultural plant production systems in protected environments enables the creation of tailor-made light scenarios for improved plant cultivation and induced defense against herbivorous insects. In this study, broccoli (Brassica oleracea var. italica plants were grown in a climate chamber under broad spectra photosynthetic active radiation (PAR and were additionally treated with the following narrow-bandwidth light generated with LEDs: UV-A (365 nm, violet (420 nm, blue (470 nm, or green (515 nm. We determined the influence of narrow-bandwidth light on broccoli plant growth, secondary plant metabolism (flavonol glycosides and glucosinolates, and plant-mediated light effects on the performance and behavior of the specialized cabbage aphid Brevicoryne brassicae. Green light increased plant height more than UV-A, violet, or blue LED treatments. Among flavonol glycosides, specific quercetin and kaempferol glycosides were increased under violet light. The concentration of 3-indolylmethyl glucosinolate in plants was increased by UV-A treatment. B. brassicae performance was not influenced by the different light qualities, but in host-choice tests, B. brassicae preferred previously blue-illuminated plants (but not UV-A-, violet-, or green-illuminated plants over control plants.

  7. Mono- and bimetallic nanoparticles decorated KTaO3 photocatalysts with improved Vis and UV-Vis light activity

    Science.gov (United States)

    Krukowska, Anna; Trykowski, Grzegorz; Winiarski, Michal Jerzy; Klimczuk, Tomasz; Lisowski, Wojciech; Mikolajczyk, Alicja; Pinto, Henry P.; Zaleska-Medynska, Adriana

    2018-05-01

    Novel mono- and bimetallic nanoparticles (MNPs and BNPs) decorated surface of perovskite-type KTaO3 photocatalysts were successfully synthesized by hydrothermal reaction of KTaO3 followed by photodeposition of MNPs/BNPs. The effect of noble metal type (MNPs = Au, Ag, Pt, Pd, Rh, Ru or BNPs = Au/Pt, Ag/Pd, Rh/Ru), amount of metal precursor (0.5, 1.0, 1.5 or 2.0 wt%) as well as photoreduction method (simultaneous (both) or subsequent (seq) deposition of two metals) on the physicochemical and photocatalytic properties of MNPs- and BNPs-KTaO3 have been investigated. All as-prepared photocatalysts were subsequently characterized by UV-Vis diffuse reflectance spectroscopy (DRS), Brunauer-Emmett-Teller (BET) specific surface area and pore size distribution measurement, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), powder X-ray diffraction (PXRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) emission spectroscopy. The crystal structure was performed using visualization for electronic and structural analysis (VESTA). The photocatalytic activity under Vis light irradiation was estimated in phenol degradation in aqueous phase and toluene removal in gas phase, while under UV-Vis light irradiation was measured amount of H2 generation from formic acid solution. The absorption properties of O2 and H2O molecules on KTaO3(1 0 0) surface supported by Au or Au/Pt NPs was also investigated using density-functional theory (DFT). The experimental results show that, both MNPs-KTaO3 and BNPs-KTaO3 exhibit greatly enhanced pollutant decomposition efficiency under Vis light irradiation and highly improved H2 production under UV-Vis light irradiation compared with pristine KTaO3. MNPs deposition on KTaO3 surface effects by disperse metal particle size ranging from 11 nm (Ru NPs) to 112 nm (Au NPs). Simultaneous addition of Au/Pt precursors results in formation of agglomerated

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

    International Nuclear Information System (INIS)

    Phillipson, R.; McMillan, T.J.

    2003-01-01

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

  9. VUV/UV light inducing accelerated phenol degradation with a low electric input.

    Science.gov (United States)

    Li, Mengkai; Wen, Dong; Qiang, Zhimin; Kiwi, John

    2017-01-23

    This study presents the first evidence for the accelerated degradation of phenol by Fenton's reagent in a mini-fluidic VUV/UV photoreaction system (MVPS). A low-pressure mercury lamp used in the MVPS led to a complete degradation of phenol within 4-6 min. The HO˙ and HO 2 ˙ originating from both Fenton's reagent and VUV photolysis of water were identified with suitable radical scavengers. The effects of initial concentrations of phenol, H 2 O 2 and Fe 3+ as well as solution pH on phenol degradation kinetics were examined. Increasing the initial phenol concentration slowed down the phenol degradation, whereas increasing the initial H 2 O 2 or Fe 3+ concentration accelerated the phenol degradation. The optimal solution pH was 3.7. At both 254 and 185 nm, increasing phenol concentration enhanced its absorption for the incident photons. The reaction mechanism for the degradation of phenol was suggested consistent with the results obtained. This study indicates that the VUV/UV photo-Fenton process has potential applications in the treatment of industrial wastewater containing phenol and related aromatic pollutants.

  10. UV light induced photodegradation of malachite green on TiO2 nanoparticles

    International Nuclear Information System (INIS)

    Chen, C.C.; Lu, C.S.; Chung, Y.C.; Jan, J.L.

    2007-01-01

    The photodegradation of malachite green (MG), a cationic triphenylmethane dye, is examined both under different pH values and amounts of TiO 2 . After 15 W UV-365 nm irradiation for 4 h, ca. 99.9% of MG was degraded with addition of 0.5 g L -1 TiO 2 to solutions containing 50 mg L -1 of the MG dye. The HPLC-PDA-ESI-MS technique was used to obtain a better understanding on the mechanistic details of this TiO 2 -assisted photodegradation of the MG dye with UV irradiation. Five intermediates of the process were separated, identified, and characterized for the first time. The results indicated that the N-de-methylation degradation of MG dye took place in a stepwise manner to yield mono-, di-, tri-, and tetra-N-de-methylated MG species generated during the processes. Under acidic conditions, the results indicated that the photodegradation mechanism is favorable to cleavage of the whole conjugated chromophore structure of the MG dye. Under basic conditions, the results showed that the photodegradation mechanism is favorable to a formation of a series of N-de-methylated intermediates of the MG dye

  11. Europium-activated barium/strontium silicates for near-UV light emitting diode applications

    Energy Technology Data Exchange (ETDEWEB)

    Han, J.K. [University of California, San Diego, Materials Science and Engineering Program, La Jolla, CA 92093 (United States); Hannah, M.E.; Piquette, A. [OSRAM SYLVANIA Central Research, 71 Cherry Hill Drive Beverly, MA 01915 (United States); Micone, J. [University of California, San Diego, Materials Science and Engineering Program, La Jolla, CA 92093 (United States); Hirata, G.A. [Centro de Nanociencias y Nanotecnolgia, Universidad Nacional Autonoma de Mexico, Km. 107 Carretera Tijuana-Ensenada Apdo, Ensenada, MX CP 22860 (Mexico); Talbot, J.B. [University of California, San Diego, Materials Science and Engineering Program, La Jolla, CA 92093 (United States); University of California, San Diego, Department of Nanoengineering, La Jolla, CA 92093 (United States); Mishra, K.C. [OSRAM SYLVANIA Central Research, 71 Cherry Hill Drive Beverly, MA 01915 (United States); McKittrick, J., E-mail: jmckittrick@UCSD.Edu [University of California, San Diego, Materials Science and Engineering Program, La Jolla, CA 92093 (United States); University of California, San Diego, Department of Mechanical and Aerospace Engineering, La Jolla, CA 92093 (United States)

    2013-01-15

    This paper reports on the luminescence properties of submicron-sized green-yellow emitting (Ba{sub 1-x}Sr{sub x}Eu{sub 0.03}){sub 2}SiO{sub 4} (0{<=}x{<=}1) phosphors. These phosphors were prepared by a modified sol-gel/Pechini method. The X-ray diffraction analysis shows that the single phase products are obtained. The particle size - ranges from 200 to 500 nm with a spherical or needlelike shape depending on x. These phosphors show strong absorption in the near UV range and the photoluminescence emission spectra consist of a strong broad green-yellow band centered between 512 and 570 nm, depending on x. Furthermore, the phosphors have high quantum efficiencies: 94% for x=0 and 85% for x=0.25. The emission lifetime at 400 K is 97% of that at 40 K, demonstrating good thermal stability. - Highlights: Black-Right-Pointing-Pointer (Ba{sub 1-x}Sr{sub x}Eu{sub 0.03}){sub 2}SiO{sub 4} (0{<=}x{<=}1) phosphors were prepared by a sol-gel/Pechini method. Black-Right-Pointing-Pointer Submicron-sized (200-500 nm) particle had a spherical or needlelike morphology. Black-Right-Pointing-Pointer Strong absorption and high quantum efficiencies (85-94%) in the near UV range. Black-Right-Pointing-Pointer Emission lifetime at 400 K is 97% of that at 40 K, showing good thermal stability.

  12. Luminescence and conductivity studies on CVD diamond exposed to UV light

    CERN Document Server

    Bizzarri, A; Bruzzi, M; Sciortino, S

    1999-01-01

    The photoluminescence (PL), thermoluminescence (TL) and thermally stimulated currents (TSC) of four high-quality CVD diamond films have been investigated in the range of temperatures between 300 and 700 K. The sample excitation has been carried out by means of an UV xenon lamp and UV laser lines. The features of the signals have been found equal to those obtained from particle excitation. The TL analysis shows the existence of several deep traps with activation energies between 0.6 and 1.0 eV. The contribution to the TL signal from different traps has been singled out by means of successive annealing processes. The TL results are in good agreement with those obtained from TSC measurements. The combined use of the two techniques allows a precise determination of the trap parameters. The spectral content of the TL response has also been compared with the PL signal in order to investigate the recombination process. This analysis shows that, in this temperature range, the TL signal is likely due to recombination ...

  13. Luminescence and conductivity studies on CVD diamond exposed to UV light

    Science.gov (United States)

    Bizzarri, A.; Bogani, F.; Bruzzi, M.; Sciortino, S.

    1999-04-01

    The photoluminescence (PL), thermoluminescence (TL) and thermally stimulated currents (TSC) of four high-quality CVD diamond films have been investigated in the range of temperatures between 300 and 700 K. The sample excitation has been carried out by means of an UV xenon lamp and UV laser lines. The features of the signals have been found equal to those obtained from particle excitation. The TL analysis shows the existence of several deep traps with activation energies between 0.6 and 1.0 eV. The contribution to the TL signal from different traps has been singled out by means of successive annealing processes. The TL results are in good agreement with those obtained from TSC measurements. The combined use of the two techniques allows a precise determination of the trap parameters. The spectral content of the TL response has also been compared with the PL signal in order to investigate the recombination process. This analysis shows that, in this temperature range, the TL signal is likely due to recombination from bound states rather than due to radiative free to bound transitions, as generally assumed in TL theory. The TSC signal is likely to arise from impurity band rather than from free carriers conduction.

  14. Luminescence and conductivity studies on CVD diamond exposed to UV light

    International Nuclear Information System (INIS)

    Bizzarri, A.; Bogani, F.; Bruzzi, M.; Sciortino, S.

    1999-01-01

    The photoluminescence (PL), thermoluminescence (TL) and thermally stimulated currents (TSC) of four high-quality CVD diamond films have been investigated in the range of temperatures between 300 and 700 K. The sample excitation has been carried out by means of an UV xenon lamp and UV laser lines. The features of the signals have been found equal to those obtained from particle excitation. The TL analysis shows the existence of several deep traps with activation energies between 0.6 and 1.0 eV. The contribution to the TL signal from different traps has been singled out by means of successive annealing processes. The TL results are in good agreement with those obtained from TSC measurements. The combined use of the two techniques allows a precise determination of the trap parameters. The spectral content of the TL response has also been compared with the PL signal in order to investigate the recombination process. This analysis shows that, in this temperature range, the TL signal is likely due to recombination from bound states rather than due to radiative free to bound transitions, as generally assumed in TL theory. The TSC signal is likely to arise from impurity band rather than from free carriers conduction

  15. Luminescence and conductivity studies on CVD diamond exposed to UV light

    Energy Technology Data Exchange (ETDEWEB)

    Bizzarri, A.; Bogani, F.; Bruzzi, M.; Sciortino, S

    1999-04-21

    The photoluminescence (PL), thermoluminescence (TL) and thermally stimulated currents (TSC) of four high-quality CVD diamond films have been investigated in the range of temperatures between 300 and 700 K. The sample excitation has been carried out by means of an UV xenon lamp and UV laser lines. The features of the signals have been found equal to those obtained from particle excitation. The TL analysis shows the existence of several deep traps with activation energies between 0.6 and 1.0 eV. The contribution to the TL signal from different traps has been singled out by means of successive annealing processes. The TL results are in good agreement with those obtained from TSC measurements. The combined use of the two techniques allows a precise determination of the trap parameters. The spectral content of the TL response has also been compared with the PL signal in order to investigate the recombination process. This analysis shows that, in this temperature range, the TL signal is likely due to recombination from bound states rather than due to radiative free to bound transitions, as generally assumed in TL theory. The TSC signal is likely to arise from impurity band rather than from free carriers conduction.

  16. A comparison study of Riboflavin/UV-A and Rose-Bengal/Green light cross-linking of the rabbit corneas using optical coherence elastography

    Science.gov (United States)

    Li, Jiasong; Singh, Manmohan; Han, Zhaolong; Vantipalli, Srilatha; Liu, Chih-Hao; Wu, Chen; Raghunathan, Raksha; Kazemi, Tina; Twa, Michael D.; Larin, Kirill V.

    2016-03-01

    The biomechanical properties of the cornea are critical factors which determine its health and subsequent visual acuity. Keratoconus is a structural degeneration of the cornea which can diminish vision quality. Riboflavin/UV-A corneal collagen cross-linking (UV-CXL) is an emerging treatment that increases the stiffness of the cornea and improves its ability to resist further degeneration. While UV-CXL has shown great promise for effective therapy of the keratoconus, there are concerns associated with the UV irradiation, such as keratocyte cytotoxicity. Rose-bengal/green light corneal collagen cross-linking (RGX) has been proposed as an alternative to UV-CXL. Because of the high absorbance of the rose-bengal dye at green wavelengths, the treatment time is significantly shorter than with UV-CXL. Moreover, because green light is used in lieu of UV irradiation, there are no cytotoxic side-effects. In this study, noncontact optical coherence elastography (OCE) was used to compare the outcomes of UV-CXL and RGX treatment in rabbit cornea. Low-amplitude (micrometer scale) elastic waves were induced by a focused air-pulse loading system. The elastic wave propagation was then imaged by a phase-stabilized swept source OCE (PhS-SSOCE) system. The changes in the viscoelasticity of the corneas were quantified by a previously developed modified Rayleigh Lamb frequency model. The depth-resolved micro-scale phase-velocity distribution in the cornea was used to reveal the depth-wise heterogeneity before and after both cross-linking techniques. Our results show that UV-CXL and RGX increased the stiffness of the corneas by ~54% and ~5% while reducing the viscosity by ~42% and ~17%, respectively. The depth-wise phase velocities showed that UV-CXL affected the anterior ~1/3 of the corneas, while RGX only affected the anterior ~1/7 of the corneas.

  17. Tunable UV- and Visible-Light Photoresponse Based on p-ZnO Nanostructures/n-ZnO/Glass Peppered with Au Nanoparticles.

    Science.gov (United States)

    Hsu, Cheng-Liang; Lin, Yu-Hong; Wang, Liang-Kai; Hsueh, Ting-Jen; Chang, Sheng-Po; Chang, Shoou-Jinn

    2017-05-03

    UV- and visible-light photoresponse was achieved via p-type K-doped ZnO nanowires and nanosheets that were hydrothermally synthesized on an n-ZnO/glass substrate and peppered with Au nanoparticles. The K content of the p-ZnO nanostructures was 0.36 atom %. The UV- and visible-light photoresponse of the p-ZnO nanostructures/n-ZnO sample was roughly 2 times higher than that of the ZnO nanowires. The Au nanoparticles of various densities and diameter sizes were deposited on the p-ZnO nanostructures/n-ZnO samples by a simple UV photochemical reaction method yielding a tunable and enhanced UV- and visible-light photoresponse. The maximum UV and visible photoresponse of the Au nanoparticle sample was obtained when the diameter size of the Au nanoparticle was approximately 5-35 nm. On the basis of the localized surface plasmon resonance effect, the UV, blue, and green photocurrent/dark current ratios of Au nanoparticle/p-ZnO nanostructures/n-ZnO are ∼1165, ∼94.6, and ∼9.7, respectively.

  18. Final LDRD report : development of advanced UV light emitters and biological agent detection strategies.

    Energy Technology Data Exchange (ETDEWEB)

    Figiel, Jeffrey James; Crawford, Mary Hagerott; Banas, Michael Anthony; Farrow, Darcie; Armstrong, Andrew M.; Serkland, Darwin Keith; Allerman, Andrew Alan; Schmitt, Randal L.

    2007-12-01

    We present the results of a three year LDRD project which has focused on the development of novel, compact, ultraviolet solid-state sources and fluorescence-based sensing platforms that apply such devices to the sensing of biological and nuclear materials. We describe our development of 270-280 nm AlGaN-based semiconductor UV LEDs with performance suitable for evaluation in biosensor platforms as well as our development efforts towards the realization of a 340 nm AlGaN-based laser diode technology. We further review our sensor development efforts, including evaluation of the efficacy of using modulated LED excitation and phase sensitive detection techniques for fluorescence detection of bio molecules and uranyl-containing compounds.

  19. Loss of inducible photorepair in a frog cell line hypersensitive to solar UV light

    International Nuclear Information System (INIS)

    Chao, C.C.-K.

    1987-01-01

    The induction of enzymatic photorepair (EPR) in ICR 2A frog cells and a derived mutant cell line DRP36 hypersensitive to solar UV was studied. Using clonogenic assays, when induced wild-type cells demonstrated an 8-fold increase of EPR the mutant cells displayed a near-background level of inducible EPR. The constitutive EPR in mutant cells, however, was the same as in wild-type cells. A mixed culture of ICR 2A and DRP36 cells showed an intermediate inducible EPR depending upon the cell ratio. Inducible EPR was also detected at the DNA level in wild-type cells, but not in mutant cells. 29 refs.; 2 figs.; 2 tabs

  20. Light - Instead of UV Protection: New Requirements for Skin Cancer Prevention.

    Science.gov (United States)

    Zastrow, Leonhard; Lademann, Jürgen

    2016-03-01

    The requirements on sunscreens have essentially changed, since some years ago it was demonstrated that approximately 50% of free radicals, that are formed in the skin by solar radiation, originate from the visible and infrared regions of the solar spectrum. In addition, a critical radical concentration threshold could be found. If this concentration, the free radical threshold value (FRTV), is exceeded, sunburn, immunosuppression and skin cancer may develop. Application of sunscreens and lotions protects against sunburn in the UV region of the solar spectrum and therefore is frequently used to extend people's stay in the sun. However, this behaviour can enhance the concentration of free radicals formed in the visible and infrared regions of the solar spectrum, so that the critical radical threshold is exceeded and the skin may be damaged. Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

  1. Real-time reconfigurable devices implemented in UV-light programmable floating-gate CMOS

    Energy Technology Data Exchange (ETDEWEB)

    Aunet, Snorre

    2002-06-01

    This dissertation describes using theory, computer simulations and laboratory measurements a new class of real time reconfigurable UV-programmable floating-gate circuits operating with current levels typically in the pA to {mu}A range, implemented in a standard double-poly CMOS technology. A new design method based on using the same basic two-MOSFET circuits extensively is proposed, meant for improving the opportunities to make larger FGUVMOS circuitry than previously reported. By using the same basic circuitry extensively, instead of different circuitry for basic digital functions, the goal is to ease UV-programming and test and save circuitry on chip and I/O-pads. Matching of circuitry should also be improved by using this approach. Compact circuitry can be made, reducing wiring and active components. Compared to earlier FGUVMOS approaches the number of transistors for implementing the CARRY' of a FULL-ADDER is reduced from 22 to 2. A complete FULL-ADDER can be implemented using only 8 transistors. 2-MOSFET circuits able to implement CARRY', NOR, NAND and INVERT functions are demonstrated by measurements on chip, working with power supply voltages ranging from 800 mV down to 93 mV. An 8-transistor FULL-ADDER might use 2500 times less energy than a FULL-ADDER implemented using standard cells in the same 0.6 {mu}m CMOS technology while running at 1 MHz. The circuits are also shown to be a new class of linear threshold elements, which is the basic building blocks of neural networks. Theory is developed as a help in the design of floating-gate circuits.

  2. Protection from UV light is an evolutionarily conserved feature of the haematopoietic niche

    Science.gov (United States)

    Kapp, Friedrich G.; Perlin, Julie R.; Hagedorn, Elliott J.; Gansner, John M.; Schwarz, Daniel E.; O'Connell, Lauren A.; Johnson, Nicholas; Amemiya, Chris; Fisher, David E.; Wolfle, Ute; Trompouki, Eirini; Niemeyer, Charlotte M.; Driever, Wolfgang; Zon, Leonard I.

    2018-01-01

    Haematopoietic stem and progenitor cells (HSPCs) require a specific microenvironment, the haematopoietic niche, which regulates HSPC behaviour. The location of this niche varies across species, but the evolutionary pressures that drive HSPCs to different microenvironments remain unknown. The niche is located in the bone marrow in adult mammals, whereas it is found in other locations in non-mammalian vertebrates, for example, in the kidney marrow in teleost fish. Here we show that a melanocyte umbrella above the kidney marrow protects HSPCs against ultraviolet light in zebrafish. Because mutants that lack melanocytes have normal steady-state haematopoiesis under standard laboratory conditions, we hypothesized that melanocytes above the stem cell niche protect HSPCs against ultraviolet-light-induced DNA damage. Indeed, after ultraviolet-light irradiation, unpigmented larvae show higher levels of DNA damage in HSPCs, as indicated by staining of cyclobutane pyrimidine dimers and have reduced numbers of HSPCs, as shown by cmyb (also known as myb) expression. The umbrella of melanocytes associated with the haematopoietic niche is highly evolutionarily conserved in aquatic animals, including the sea lamprey, a basal vertebrate. During the transition from an aquatic to a terrestrial environment, HSPCs relocated into the bone marrow, which is protected from ultraviolet light by the cortical bone around the marrow. Our studies reveal that melanocytes above the haematopoietic niche protect HSPCs from ultraviolet-light-induced DNA damage in aquatic vertebrates and suggest that during the transition to terrestrial life, ultraviolet light was an evolutionary pressure affecting the location of the haematopoietic niche.

  3. Photocatalytic Degradation of Toluene, Butyl Acetate and Limonene under UV and Visible Light with Titanium Dioxide-Graphene Oxide as Photocatalyst

    Directory of Open Access Journals (Sweden)

    Birte Mull

    2017-01-01

    Full Text Available Photocatalysis is a promising technique to reduce volatile organic compounds indoors. Titanium dioxide (TiO2 is a frequently-used UV active photocatalyst. Because of the lack of UV light indoors, TiO2 has to be modified to get its working range shifted into the visible light spectrum. In this study, the photocatalytic degradation of toluene, butyl acetate and limonene was investigated under UV LED light and blue LED light in emission test chambers with catalysts either made of pure TiO2 or TiO2 modified with graphene oxide (GO. TiO2 coated with different GO amounts (0.75%–14% were investigated to find an optimum ratio for the photocatalytic degradation of VOC in real indoor air concentrations. Most experiments were performed at a relative humidity of 0% in 20 L emission test chambers. Experiments at 40% relative humidity were done in a 1 m³ emission test chamber to determine potential byproducts. Degradation under UV LED light could be achieved for all three compounds with almost all tested catalyst samples up to more than 95%. Limonene had the highest degradation of the three selected volatile organic compounds under blue LED light with all investigated catalyst samples.

  4. Polar and semipolar GaN/Al0.5Ga0.5N nanostructures for UV light emitters

    Science.gov (United States)

    Brault, J.; Rosales, D.; Damilano, B.; Leroux, M.; Courville, A.; Korytov, M.; Chenot, S.; Vennéguès, P.; Vinter, B.; De Mierry, P.; Kahouli, A.; Massies, J.; Bretagnon, T.; Gil, B.

    2014-06-01

    AlxGa1-xN-based ultra-violet (UV) light emitting diodes (LEDs) are seen as the best solution for the replacement of traditional mercury lamp technology. By adjusting the Al concentration, a large emission spectrum range from 360 nm (GaN) down to 200 nm (AlN) can be covered. Owing to the large density of defects typically present in AlxGa1-xN materials usually grown on sapphire substrates, LED efficiencies still need to be improved. Taking advantage of the 3D carrier confinement, quantum dots (QDs) are among the solutions currently under investigation to improve the performances of UV LEDs. The objectives of this work are to present and discuss the morphological and optical properties of GaN nanostructures grown by molecular beam epitaxy on the (0 0 0 1) and the (11-22) orientations of Al0.5Ga0.5N. In particular, the dependence of the morphological properties of the nanostructures on the growth conditions and the surface orientation will be presented. The optical characteristics as a function of the nanostructure design (size, shape and dimensionality) will also be shown and discussed. The electroluminescence characteristics of a first series of QD-based GaN/Al0.5Ga0.5N LEDs grown on the polar (0 0 0 1) plane will be investigated.

  5. Polar and semipolar GaN/Al0.5Ga0.5N nanostructures for UV light emitters

    International Nuclear Information System (INIS)

    Brault, J; Damilano, B; Leroux, M; Courville, A; Korytov, M; Chenot, S; Vennéguès, P; Vinter, B; De Mierry, P; Kahouli, A; Massies, J; Rosales, D; Bretagnon, T; Gil, B

    2014-01-01

    Al x Ga 1−x N-based ultra-violet (UV) light emitting diodes (LEDs) are seen as the best solution for the replacement of traditional mercury lamp technology. By adjusting the Al concentration, a large emission spectrum range from 360 nm (GaN) down to 200 nm (AlN) can be covered. Owing to the large density of defects typically present in Al x Ga 1−x N materials usually grown on sapphire substrates, LED efficiencies still need to be improved. Taking advantage of the 3D carrier confinement, quantum dots (QDs) are among the solutions currently under investigation to improve the performances of UV LEDs. The objectives of this work are to present and discuss the morphological and optical properties of GaN nanostructures grown by molecular beam epitaxy on the (0 0 0 1) and the (11–22) orientations of Al 0.5 Ga 0.5 N. In particular, the dependence of the morphological properties of the nanostructures on the growth conditions and the surface orientation will be presented. The optical characteristics as a function of the nanostructure design (size, shape and dimensionality) will also be shown and discussed. The electroluminescence characteristics of a first series of QD-based GaN/Al 0.5 Ga 0.5 N LEDs grown on the polar (0 0 0 1) plane will be investigated. (invited article)

  6. Monitoring light-induced structural changes of Channelrhodopsin-2 by UV-visible and Fourier transform infrared spectroscopy.

    Science.gov (United States)

    Ritter, Eglof; Stehfest, Katja; Berndt, Andre; Hegemann, Peter; Bartl, Franz J

    2008-12-12

    Channelrhodopsin-2 (ChR2) is a microbial type rhodopsin and a light-gated cation channel that controls phototaxis in Chlamydomonas. We expressed ChR2 in COS-cells, purified it, and subsequently investigated this unusual photoreceptor by flash photolysis and UV-visible and Fourier transform infrared difference spectroscopy. Several transient photoproducts of the wild type ChR2 were identified, and their kinetics and molecular properties were compared with those of the ChR2 mutant E90Q. Based on the spectroscopic data we developed a model of the photocycle comprising six distinguishable intermediates. This photocycle shows similarities to the photocycle of the ChR2-related Channelrhodopsin of Volvox but also displays significant differences. We show that molecular changes include retinal isomerization, changes in hydrogen bonding of carboxylic acids, and large alterations of the protein backbone structure. These alterations are stronger than those observed in the photocycle of other microbial rhodopsins like bacteriorhodopsin and are related to those occurring in animal rhodopsins. UV-visible and Fourier transform infrared difference spectroscopy revealed two late intermediates with different time constants of tau = 6 and 40 s that exist during the recovery of the dark state. The carboxylic side chain of Glu(90) is involved in the slow transition. The molecular changes during the ChR2 photocycle are discussed with respect to other members of the rhodopsin family.

  7. Heterogeneous Catalysis by Tetraethylammonium Tetrachloroferrate of the Photooxidation of Toluene by Visible and Near-UV Light

    Directory of Open Access Journals (Sweden)

    Kelsie R. Barnard

    2018-02-01

    Full Text Available Titanium dioxide is the most extensively used heterogeneous catalyst for the photooxidation of toluene and other hydrocarbons, but it has low utility for the synthesis of benzyl alcohol, of which little is produced, or benzaldehyde, due to further oxidation to benzoic acid and cresol, among other oxidation products, and eventually complete mineralization to CO2. Et4N[FeCl4] functions as a photocatalyst through the dissociation of chlorine atoms, which abstract hydrogen from toluene, and the photooxidation of toluene proceeds only as far as benzyl alcohol and benzaldehyde. Unlike TiO2, which requires ultraviolet (UV irradiation, Et4N[FeCl4] catalyzes the photooxidation of toluene with visible light alone. Even under predominantly UV irradiation, the yield of benzyl alcohol plus benzaldehyde is greater with Et4N[FeCl4] than with TiO2. Et4N[FeCl4] photocatalysis yields benzyl chloride as a side product, but it can be minimized by restricting irradiation to wavelengths above 360 nm and by the use of long irradiation times. The photonic efficiency of oxidation in one experiment was found to be 0.042 mol/einstein at 365 nm. The use of sunlight as the irradiation source was explored.

  8. TiO{sub 2}/WO{sub 3} photoactive bilayers in the UV-Vis light region

    Energy Technology Data Exchange (ETDEWEB)

    Vasilaki, E. [University of Crete, Department of Chemistry, Heraklion, Crete (Greece); Technological Educational Institute of Crete, Center of Materials Technology and Photonics, School of Engineering, Heraklion, Crete (Greece); Vernardou, D. [Technological Educational Institute of Crete, Center of Materials Technology and Photonics, School of Engineering, Heraklion, Crete (Greece); Kenanakis, G.; Katsarakis, N. [Technological Educational Institute of Crete, Center of Materials Technology and Photonics, School of Engineering, Heraklion, Crete (Greece); Foundation for Research and Technology-Hellas, Institute of Electronic Structure and Laser, Vassilika Vouton, P.O. Box 1385, Heraklion, Crete (Greece); Vamvakaki, M. [Foundation for Research and Technology-Hellas, Institute of Electronic Structure and Laser, Vassilika Vouton, P.O. Box 1385, Heraklion, Crete (Greece); University of Crete, Department of Materials Science and Technology, Heraklion, Crete (Greece)

    2017-04-15

    In this work, photoactive bilayered films consisting of anatase TiO{sub 2} and monoclinic WO{sub 3} were synthesized by a sol-gel route. Titanium isopropoxide and tungsten hexachloride were used as metal precursors and deposition was achieved by spin-coating on Corning glass substrates. The samples were characterized by X-ray diffraction, photoluminescence, UV-Vis, and Raman spectroscopy, as well as field emission scanning electron microscopy. The prepared immobilized catalysts were tested for their photocatalytic performance by the decolorization of methylene blue in aqueous matrices, under UV-Vis light irradiation. The annealing process influenced the crystallinity of the bilayered films, while the concentration of the tungsten precursor solution and the position of the tungsten trioxide layer further affected their photocatalytic performance. In particular, the photocatalytic performance of the bilayered films was optimized at a concentration of 0.1 M of the WO{sub 3} precursor solution, when deposited as an overlying layer on TiO{sub 2} by two annealing steps (∝76% methylene blue decolorization in 300 min of irradiation versus ∝59% in the case of a bare TiO{sub 2} film). In general, the coupled layer catalysts exhibited superior photoactivity compared to that of bare TiO{sub 2} films with WO{sub 3} acting as an electron trap, resulting, therefore, in a more efficient electron-hole separation and inhibiting their recombination. (orig.)

  9. Bactericidal activity under UV and visible light of cotton fabrics coated with anthraquinone-sensitized TiO2

    KAUST Repository

    Rahal, Raed

    2013-06-01

    This study describes a method derived from ISO/TC 206/SC specifications to assess the bactericidal activity against a bacterial strain, Pseudomonas fluorescens, of various photocatalytic fabrics, under UVA and filtered visible light. The experimental method allowed the accurate quantification of bacteria survival on photoactive surfaces and films under UVA and UV-free visible irradiation. Cotton fabrics coated with TiO2, anthraquinone or anthraquinone-sensitized TiO2 display a significant bactericidal efficiency. TiO2-coated fabrics are very efficient against P. fluorescens after 4 h UVA irradiation (bacteria survival below the detection limit). Under UVA-free visible light, anthraquinone-sensitized TiO2 coated fabrics induced a significant bactericidal activity after 2 h irradiation, while anthraquinone alone-coated fabrics were not as efficient and TiO2 coated fabrics were almost inefficient. These results show that although exhibiting a weak n-π* band in the 350-420 nm range, anthraquinone is a good candidate as an efficient visible light photosensitizer. A synergy effect between anthraquinone and TiO2 was demonstrated. A possible reaction mechanism, involving a synergy effect for singlet oxygen formation with anthraquinone-sensitized TiO2 is proposed to account for these results. © 2012 Elsevier B.V. All rights reserved.

  10. 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.

  11. Repair replication in replicating and nonreplicating DNA after irradiation with uv light

    Energy Technology Data Exchange (ETDEWEB)

    Slor, H.; Cleaver, J.E.

    1978-06-01

    Ultraviolet light induces more pyrimidine dimers and more repair replication in DNA that replicates within 2 to 3 h of irradiation than in DNA that does not replicate during this period. This difference may be due to special conformational changes in DNA and chromatin that might be associated with semiconservative DNA replication.

  12. A study on heterogeneous photocatalytic degradation of various organic compounds using N-Tio2 under Uv-light irradiation

    Science.gov (United States)

    Srujana, Dhegam; Sailu, Chinta

    2018-04-01

    The aim of this work is to determine the photocatalytic degradation of mixture of four selected organic compounds are Congo Red (CR), Methylene Blue (MB), Diclofenaec (DC), 4-Chlorophenol (4-CP) have been subjected to Photo catalytic degradation by Ultraviolet (λ=254nm) radiation in presence of Nitrogen-doped Titanium dioxide (N-TiO2) catalyst. This paper focused on the enhancement of photo catalysis by modification of TiO2 employing non-metal ion (Nitrogen) doping. Experiments are conducted with a mixture of equal proportions of organic compounds (CR, MB, DC, and 4-CP) with combined concentrations of 10, 20, 30, 40 and 50 mg/l in water in a batch reactor in presence of N-TiO2catalyst with UV light (λ=254nm). The rate of degradation of each compound is determined by using spectrophotometer. The kinetics of degradation of the selected organic compounds is followed first order rate.

  13. PHOTO-CATALYST DEGRADATION OF TARTRAZINE COMPOUND IN WASTEWATER USING TiO2 AND UV LIGHT

    Directory of Open Access Journals (Sweden)

    SALAM K. AL-DAWERY

    2013-12-01

    Full Text Available Organic contaminants present in industrial wastewater are of major concern with respect to the health of the general public. Photo-catalytic process, one of the Advanced Oxidation Processes, is a promising technology for remediation of organic pollutants at ambient conditions. Photo-catalytic processes in the presence of TiO2 provide an interesting method to destroy hazardous organic contaminants. The experimental results showed that considerable degradation of Tartrazine organic compound has been achieved by combination of TiO2 and UV light, the process followed first order kinetics. The results showed that the increased level of TiO2 concentration does not necessarily increase the rate of degradation of organic compounds. Also, it was found that the higher the TiO2 concentrations the higher the pH values and more oscillatory behaviors were observed. Not much effect has been noted on the process due to temperature variation.

  14. Dictating photoreactivity through restricted bond rotations: cross-photoaddition of atropisomeric acrylimide derivatives under UV/visible-light irradiation.

    Science.gov (United States)

    Iyer, Akila; Jockusch, Steffen; Sivaguru, J

    2014-11-13

    Nonbiaryl atropisomeric acrylimides underwent facile [2 + 2] photocycloaddition leading to cross-cyclobutane adducts with very high stereospecificity (enantiomeric excess (ee): 99% and diastereomeric excess (de): 99%). The photoreactions proceeded smoothly in isotropic media for both direct and triplet sensitized irradiations. The reactions were also found to be very efficient in the solid state where the same cross-cyclobutane adduct was observed. Photophysical studies enabled us to understand the excited-state photochemistry of acrylimides. The triplet energy was found to be ∼63 kcal/mol. The reactions proceeded predominantly via a singlet excited state upon direct irradiation with very poor intersystem crossing that was ascertained by quantification of the generated singlet oxygen. The reactions progressed smoothly with triplet sensitization with UV or visible-light irradiations. Laser flash photolysis experiments established the triplet transient of atropisomeric acrylimides with a triplet lifetime at room temperature of ∼40 ns.

  15. A unique UV flare in the optical light curve of the quasar J004457.9+412344

    Directory of Open Access Journals (Sweden)

    Hatzidimitriou D.

    2012-12-01

    Full Text Available We found that the nova candidate J004457.9+412344 is a radio-quiet quasar at z ∼ 2. Its optical long-term light curve, covering more than half a century, shows quasar typical flux variations superimposed by a spectacular single flare lasting more than one year (observer frame. We could not find comparable light curves among the several thousand catalogued radio-quiet quasars in the stripe 82 of the Sloan Digital Sky Survey. The decreasing part of the flare light curve roughly follows a power law t−5/3. The quasar spectrum, the total energy of the flare, and the decline of the light curve are consistent with the tidal disruption of a ∼10 Mʘ giant star by a supermassive black hole of a few 108 Mʘ. We argue that the alternative explanation by gravitational microlensing is less likely, though it cannot be definitely excluded.

  16. UV light-induced DNA synthesis arrest in HeLa cells is associated with changes in phosphorylation of human single-stranded DNA-binding protein

    International Nuclear Information System (INIS)

    Carty, M.P.; Zernik-Kobak, M.; McGrath, S.; Dixon, K.

    1994-01-01

    We show that DNA replication activity in extracts of human HeLa cells decreases following UV irradiation. Alterations in replication activity in vitro parallel the UV-induced block in cell cycle progression of these cells in culture. UV irradiation also induces specific changes in the pattern of phosphorylation of the 34 kDa subunit of a DNA replication protein, human single-stranded DNA-binding protein (hSSB). The appearance of a hyperphosphorylated form of hSSB correlates with reduced in vitro DNA replication activity in extracts of UV-irradiated cells. Replication activity can be restored to these extracts in vitro by addition of purified hSSB. These results suggest that UV-induced DNA synthesis arrest may be mediated in part through phosphorylation-related alterations in the activity of hSSB, an essential component of the DNA replication apparatus. (Author)

  17. Destruction of pesticides and their formulations in water using short wavelength UV light

    International Nuclear Information System (INIS)

    Peterson, D.; Watson, D.; Winterlin, W.

    1990-01-01

    The presence of toxic materials in surface and ground water is a problem of growing significance. Increasingly, toxic anthropogenic chemicals are being detected in water supplies resulting in public concern and regulatory restrictions. Clearly, there is a need to develop methods to decontaminate not only drinking water supplies, but also the sources of contamination. Decontamination of water poses economic and logistical challenges since the pollutants are usually present in low concentrations and distributed over a wide area. A number of strategies have been proposed and tested to destroy toxic materials in water. In this study, the authors examined the effectiveness of a photoreactor equipped with a high pressure mercury vapor lamp for the destruction of three pesticides and the inert ingredient m-xylene in water. Captan, chlordane, PCNB, and m-xylene in aqueous solutions were selected as model compounds for this study based on their use, resistance to UV degradation, and potential presence in formulated pesticide materials. The factors that influence the performance of the system were investigated

  18. Absorption of UV-B to blue light radiation by leaf cuticles of selected crop plants

    International Nuclear Information System (INIS)

    Baur, P.; Stulle, K.; Schönherr, J.; Uhlig, B.

    1998-01-01

    Plants have protective pigments absorbing destructive shortwave radiation. These pigments have been found in the epidermis and mesophyll of leaves. We studied the absorption characteristics of the leaf cuticle, the outermost part of the epidermis that is directly exposed to radiation. Adaxial leaf cuticles of apple, pear, sour cherry, strawberry, cauliflower, sugarbeet, and 13 other plant species were tested. The UV-B absorption was highest in Citrus aurantium and Citrus maxima (<3 % transmittance) and lowest in sugarbeet and peach (>64 % transmittance). The absorption maxima are at wavelenghts below 320 nm. Significant absorption was also determined at 500 nm, which correlated with cuticle thickness of the plant species (r(2)=0.72). The absorption in the range of 250 to 350 nm is caused by pigments with a high extinction coefficient. This absorption is species dependent and the patterns were designated to three different types. The highest absorption was found in evergreen species. The extraction of cuticular waxes had little effect on absorption. The specific absorption of shortwave radiation by plant cuticles is probably caused by pigments covalently bound to cut in. It is known for some plant species that cuticles can contain the phenolics p-coumaric acid, ferulic acid, and vanillic acid. Mixtures of these phenolics had spectra similar to cuticles. For most species absorption of shortwave radiation by the cuticle alone does not give complete protection

  19. Sensitization by UV light of α-Al2O3:C polycrystalline detectors

    International Nuclear Information System (INIS)

    Meira B, L. C.; Rubio F, H.; Neres de A, E.; Santos, A.

    2014-08-01

    This paper describes an increase in sensitivity to gamma and beta radiation on α-Al 2 O 3 :C polycrystalline detector, which has been produced by a sol-gel process, following previous exposure to ultraviolet light. The increased sensitivity of the detector as a function of the exposure time and ultraviolet wavelength was studied. Since the main luminescent centers have emission peaks at different wavelengths, selective measurements of thermoluminescent emission intensity were done, in order to investigate the possible conversion of centers as a result of the exposition to ultraviolet light. Experimental results indicate that the nature and parameters of the luminescent centers in α-Al 2 O 3 :C sol-gel material can be very different of those in α-Al 2 O 3 :C single crystal. (author)

  20. The optoelectronic chameleon - GaN-based light emitters from the UV to green

    Energy Technology Data Exchange (ETDEWEB)

    Kneissl, Michael [Institut fuer Festkoerperphysik, Technische Universitaet Berlin (Germany)

    2008-07-01

    Group III-nitrides have evolved into one of the most versatile and important semiconductor materials for optoelectronic devices. GaN-based blue, green and white light emitting diodes have already entered many parts of everyday life and violet lasers are expected to be following soon. However, considering the extraordinary electronic properties and the wide spectral range that is accessible through nitride materials, it appears that it we have just touched the tip of the iceberg. We discuss some of the new fields of research for InAlGaN materials and devices and review progress in the development of near and deep ultraviolet light emitting diodes, as well as growth and optical properties of InN and indium rich InGaN alloys for emitter in the blue-green spectral range and beyond.

  1. Fabrication of engineered particle-doped light diffuser with a soft transparent mold of UV-curable polymer

    Science.gov (United States)

    Zhu, Jicheng; Liu, Yanhua; Shen, Su; Wu, Jianhong

    2017-11-01

    Engineered particle-doped light diffuser is realized by a simple, low-cost soft lithographic method. A flexible photopolymerizable mold is employed as an intermediate transferring template directly from the developed photoresist texture to fabricate engineered particle-doped light diffuser. The well-designed surface microstructure can directionally scatter the incident light, while the doped ultra-violet curable resin with low concentration of the 2 μm-diameter organosilicone particles can homogenize the scattering light without decreasing transmittance. Experimental results show that the measured transmittance can be as high as 96.9% with little backscattering effect over the whole visible regime. Meanwhile, the haze raises from 30% to 75% with increased dopant concentration from 1 wt% to 7 wt% and thickness of the residual layer from 10 μm to 40 μm remained in the imprinting process. The proposed engineered particle-doped light diffuser can manage scattering angle, luminance uniformity and haze, thus it has the capability of homogenizing light and eliminating striations to create more visually pleasing structured lighting in commercial and residential environments. We anticipate that the approach appears to be a strong candidate for future development because of its scalable nature, environmentally-friendly process and relatively low cost.

  2. Degradation of photovoltaic backsheet materials under multi-factor accelerated UV light exposures

    Science.gov (United States)

    Klinke, Addison G.; Gok, Abdulkerim; Ifeanyi, Silas I.; French, Roger H.; Bruckman, Laura S.

    2017-08-01

    Long term outdoor durability of photovoltaic (PV) module backsheets is critical to a module's power output over its lifetime. The use of uoropolymer-based backsheets or the addition of stabilizers to polyethylene-terephthalate (PET) and polyamide (PA) type backsheets can help extend their lifetime. This study presents the performance of 21 backsheets made of 8 different material combinations under ASTM G154 Cycle 4 accelerated light exposures. The backsheets were subjected to 4000 hours of high irradiance UVA light at a peak intensity of 1.55 W=m2 at 340 nm at 70°C with and without a condensing humidity cycle at 50°C. Backsheets were evaluated, with repeated measurements, using various evaluation techniques to identify and assess potential signs of degradation. These evaluations included the yellowness index (YI), CIE color space coordinates, and gloss at 20, 60, and 85°. The temporal evolution of the relative color change ΔE was statistically analyzed to develop a stress-response model which used the UVA light dose to predict color change. It was found that the PVF/PET/E backsheet performed the best while PET/PET/E and THV/PET/EVA backsheets performed the worst. Additionally, substantial variation in color change response, attributable to key manufacturing differences, was observed within a given material type.

  3. Using the Transient Response of WO3 Nanoneedles under Pulsed UV Light in the Detection of NH3 and NO2

    Directory of Open Access Journals (Sweden)

    Oriol Gonzalez

    2018-04-01

    Full Text Available Here we report on the use of pulsed UV light for activating the gas sensing response of metal oxides. Under pulsed UV light, the resistance of metal oxides presents a ripple due to light-induced transient adsorption and desorption phenomena. This methodology has been applied to tungsten oxide nanoneedle gas sensors operated either at room temperature or under mild heating (50 °C or 100 °C. It has been found that by analyzing the rate of resistance change caused by pulsed UV light, a fast determination of gas concentration is achieved (ten-fold improvement in response time. The technique is useful for detecting both oxidizing (NO2 and reducing (NH3 gases, even in the presence of different levels of ambient humidity. Room temperature operated sensors under pulsed UV light show good response towards ammonia and nitrogen dioxide at low power consumption levels. Increasing their operating temperature to 50 °C or 100 °C has the effect of further increasing sensitivity.

  4. Deep UV light generation by a fiber/bulk hybrid amplifier at 199 nm

    International Nuclear Information System (INIS)

    Urata, Yoshiharu; Shinozaki, Tatsuya; Wada, Yoshio; Kaneda, Yushi; Wada, Satoshi; Imai, Shinichi

    2009-01-01

    A high-pulse-repetition-frequency (PRF) pulsed light source in the deep ultraviolet region has been realized by a multiple wavelength conversion technique using a hybrid fiber/bulk amplifier system. Output of 199 nm with a power of 50 mW was achieved at 2.4 MHz PRF. The 1 μm amplifier consisted of a Yb-doped fiber amplifier and a Nd-doped YVO4 amplifier. A 1.5 μm fiber master-oscillator power amplifier was employed as the other fundamental source. The amplifiers exhibited good amplification properties in pulse energy, polarization extinction ratio, and spectrum for nonlinear wavelength conversion

  5. Chronic exposure to dim artificial light at night decreases fecundity and adult survival in Drosophila melanogaster.

    Science.gov (United States)

    McLay, L K; Green, M P; Jones, T M

    2017-07-01

    The presence of artificial light at night is expanding in geographical range and increasing in intensity to such an extent that species living in urban environments may never experience natural darkness. The negative ecological consequences of artificial night lighting have been identified in several key life history traits across multiple taxa (albeit with a strong vertebrate focus); comparable data for invertebrates is lacking. In this study, we explored the effect of chronic exposure to different night-time lighting intensities on growth, reproduction and survival in Drosophila melanogaster. We reared three generations of flies under identical daytime light conditions (2600lx) and one of four ecologically relevant ALAN treatments (0, 1, 10 or 100lx), then explored variation in oviposition, number of eggs produced, juvenile growth and survival and adult survival. We found that, in the presence of light at night (1, 10 and 100lx treatments), the probability of a female commencing oviposition and the number of eggs laid was significantly reduced. This did not translate into differences at the juvenile phase: juvenile development times and the probability of eclosing as an adult were comparable across all treatments. However, we demonstrate for the first time a direct link between chronic exposure to light at night (greater than 1lx) and adult survival. Our data highlight that ALAN has the capacity to cause dramatic shifts in multiple life history traits at both the individual and population level. Such shifts are likely to be species-specific, however a more in depth understanding of the broad-scale impact of ALAN and the relevant mechanisms driving biological change is urgently required as we move into an increasing brightly lit future. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Photocatalytic removal of doxycycline from aqueous solution using ZnO nano-particles: a comparison between UV-C and visible light.

    Science.gov (United States)

    Pourmoslemi, Shabnam; Mohammadi, Ali; Kobarfard, Farzad; Amini, Mohsen

    2016-10-01

    Zinc oxide nano-particles were synthesized, characterized and used for photocatalytic degradation of doxycycline using UV-C and visible light. Effects of several operational factors including initial pH of antibiotic solution, initial antibiotic concentration and ZnO nano-particles loading amount were investigated. Comparing photocatalytic degradation and mineralization of doxycycline under UV-C and visible light showed successful application of the method under both light sources. However, reaction rate was higher under UV-C irradiation, which degraded doxycycline almost completely in 5 hours, and 68% mineralization was achieved. Synthesized ZnO nano-particles were successfully applied for photocatalytic degradation of doxycycline in a pharmaceutical wastewater sample. The process was fitted to the pseudo first order kinetic model with rate constants in the range of 6-22(×10 -3 ) mg L -1 min -1 with respect to initial concentration of doxycycline under UV-C irradiation. The Langmuir-Hinshelwood model was also employed for describing the photocatalytic reaction with surface reaction kinetic constant k c and equilibrium adsorption constant K LH values calculated as 0.12 mg L -1 min -1 and 2.2 L mg -1 , respectively. Degradation of doxycycline was followed by UV-visible spectroscopy and a validated stability indicating high-performance liquid chromatography method that was developed using stressed samples of doxycycline and could selectively determine doxycycline in the presence of its degradation products. Mass spectrometry was used for determining final degradation products.

  7. Protection against UV and X-ray cataracts using dynamic light scattering

    Science.gov (United States)

    Giblin, Frank J.

    2005-01-01

    Static and dynamic light scattering (SLS and DLS) analysis was used to investigate the aggregation of lens proteins in a hyperbaric oxygen (HBO)/guinea pig in vivo model for nuclear cataract. Nuclear cataract, an opacity which occurs in the center of the lens, is a major type of human maturity-onset cataract for which the cause is not well-understood. HBO is commonly used in major hospitals for treating complications such as poor wound healing due to impaired blood circulation. It is known that treatment of human patients with HBO for extended periods of time can produce nuclear cataract. Guinea pigs, initially 18 months old, were treated with HBO (2.5 atm of 100% O2 for 2.5 hr) 3x per week for 7 months to increase tie level of lens nuclear light scattering. Age-matched animals were used for controls. The eyes of the animals were analyzed in vivo using an integrated static and DLS fiber optic probe in collaboration with the NASA group. DLS in vivo was used to measure the size of lens proteins at 50 different locations across the optical axis of the guinea pig lens.

  8. The influence of light spectra, UV-A, and growth regulators on the in vitro seed germination of Senecio cineraria DC.

    Directory of Open Access Journals (Sweden)

    Cristiane Pimentel Victório

    2010-10-01

    Full Text Available This study was carried out to investigate the effects of light spectra, additional UV-A, and different growth regulators on the in vitro germination of Senecio cineraria DC. Seeds were surface-sterilized and inoculated in MS medium to evaluate the following light spectra: white, white plus UV-A, blue, green, red or darkness. The maximum germinability was obtained using MS0 medium under white light (30% and MS + 0.3 mg L-1 GA3 in the absence of light (30.5%. S. cineraria seeds were indifferent to light. Blue and green lights inhibited germination. Different concentrations of gibberellic acid (GA3 (0.1; 0.4; 0.6; 0.8; 1.0 and 2.0 mg L-1 and indole-3-acetic acid IAA (0.1; 0.3 and 1.0 mg L-1 were evaluated under white light and darkness. No concentration of GA3 enhanced seed germination percentage under white light. However, when the seeds were maintained in darkness, GA3 improved germination responses in all tested concentrations, except at 1.0 mg L-1. Under white light, these concentrations also increased the germination time and reduced germination rate. Germination rate, under light or darkness, was lower using IAA compared with GA3.

  9. 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.

  10. Characterization and photocatalytic performance evaluation of various metal ion-doped microstructured TiO2 under UV and visible light.

    Science.gov (United States)

    Sahoo, Chittaranjan; Gupta, Ashok K

    2015-01-01

    Commercially available microcrystalline TiO2 was doped with silver, ferrous and ferric ion (1.0 mol %) using silver nitrate, ferrous sulfate and ferric nitrate solutions following the liquid impregnation technology. The catalysts prepared were characterised by FESEM, XRD, FTIR, DRS, particle size and micropore analysis. The photocatalytic activity of the prepared catalysts was tested on the degradation of two model dyes, methylene blue (3,7-bis (Dimethylamino)-phenothiazin-5-ium chloride, a cationic thiazine dye) and methyl blue (disodium;4-[4-[[4-(4-sulfonatoanilino)phenyl]-[4-(4-sulfonatophenyl)azaniumylidenecyclohexa-2,5-dien-1-ylidene]methyl]anilino]benzene sulfonate, an anionic triphenyl methane dye) under irradiation by UV and visible light in a batch reactor. The efficiency of the photocatalysts under UV and visible light was compared to ascertain the light range for effective utilization. The catalysts were found to have the anatase crystalline structure and their particle size is in a range of 140-250 nm. In the case of Fe(2+) doped TiO2 and Fe(3+) doped TiO2, there was a greater shift in the optical absorption towards the visible range. Under UV light, Ag(+) doped TiO2 was the most efficient catalyst and the corresponding decolorization was more than 99% for both the dyes. Under visible light, Fe(3+) doped TiO2 was the most efficient photocatalyst with more than 96% and 90% decolorization for methylene blue and methyl blue, respectively. The kinetics of the reaction under both UV and visible light was investigated using the Langmuir-Hinshelwood pseudo-first-order kinetic model. Kinetic measurements confirmed that, Ag(+) doped TiO2 was most efficient in the UV range, while Fe(3+) doped TiO2 was most efficient in the visible range.

  11. Photocatalytic degradation and mineralization of microcystin-LR under UV-A, solar and visible light using nanostructured nitrogen doped TiO2

    International Nuclear Information System (INIS)

    Triantis, T.M.; Fotiou, T.; Kaloudis, T.; Kontos, A.G.; Falaras, P.; Dionysiou, D.D.; Pelaez, M.; Hiskia, A.

    2012-01-01

    Highlights: ► N-TiO 2 exhibited effective degradation of MC-LR under UV-A, solar and visible light. ► Complete photocatalytic mineralization of MC-LR was achieved under UV-A and solar light. ► The organic nitrogen is mainly released as ammonium and nitrate ions. - Abstract: In an attempt to face serious environmental hazards, the degradation of microcystin-LR (MC-LR), one of the most common and more toxic water soluble cyanotoxin compounds released by cyanobacteria blooms, was investigated using nitrogen doped TiO 2 (N-TiO 2 ) photocatalyst, under UV-A, solar and visible light. Commercial Degussa P25 TiO 2 , Kronos and reference TiO 2 nanopowders were used for comparison. It was found that under UV-A irradiation, all photocatalysts were effective in toxin elimination. The higher MC-LR degradation (99%) was observed with Degussa P25 TiO 2 followed by N-TiO 2 with 96% toxin destruction after 20 min of illumination. Under solar light illumination, N-TiO 2 nanocatalyst exhibits similar photocatalytic activity with that of commercially available materials such as Degussa P25 and Kronos TiO 2 for the destruction of MC-LR. Upon irradiation with visible light Degussa P25 practically did not show any response, while the N-TiO 2 displayed remarkable photocatalytic efficiency. In addition, it has been shown that photodegradation products did not present any significant protein phosphatase inhibition activity, proving that toxicity is proportional only to the remaining MC-LR in solution. Finally, total organic carbon (TOC) and inorganic ions (NO 2 − , NO 3 − and NH 4 + ) determinations confirmed that complete photocatalytic mineralization of MC-LR was achieved under both UV-A and solar light.

  12. Study on activities of vanadium (IV/V) doped TiO2(R) nanorods induced by UV and visible light

    International Nuclear Information System (INIS)

    Li, Li; Liu Chunyan; Liu Yun

    2009-01-01

    Vanadium (IV/V) doped rutile TiO 2 naonorods had been successfully synthesized through a single step hydrothermal method. The photocatalyst was characterized by transmission electron microscopy (TEM), selected area electron diffraction (SAED), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), UV-vis diffusive reflectance spectroscopy (DRS) and X-ray photoelectron spectroscopy (XPS). The results showed that the doping of V ions had significant influence on the band gap energy and the surface state of TiO 2 . The photo-activities of the new catalysts were investigated under ultraviolet (UV) and visible light. The UV-photocatalytic activity of the as-prepared catalysts was hardly influenced by doping V ions; while under visible light, the samples with 1 wt% and 0.1 wt% V exhibited enhanced activity to the oxidation of methylene blue (MB) and the reduction of Cr (VI), respectively

  13. [The Influence of UV-Light on the Sub-Populational Composition and Expression of Membrane Markers of Lymphocytes of Donor Blood].

    Science.gov (United States)

    Artyukhov, V G; Basharina, O V; Zemchenkova, O V; Ryazantsev, S V

    2016-01-01

    The influence of UV-light (240-390 nm) at dozes of 151 and 755 J/m2 on the content of membrane markers of lymphocytes using the method of flow cytometry was investigated. It was demonstrated that during incubation of UV-irradiated lymphocytes the change of their populational and sub-populational composition occurs. Expression of complexes of CD3, CD 19,.CD8, CD 16, CD25 and CD95 increased. This increase was caused mainly by de novo synthesis. UV-light had immunostimulating effect on CD8+ T-lymphocyte population. Together with the increase of cytotoxic cells and NK-cells, activation of lymphocytes (increased amount of CD25+ and CD95+ cells) took place. Amount of cells undergone apoptosis or necrosis increased proportionally to the dosage. These changes were more expressed during incubation of lymphocytes in nutrition medium without autological blood serum, e.g. under deficiency of growth factors and antioxidants.

  14. The mutagenic action of UV-light irradiation on aspergillus terreus in relation to antibacterial activity

    International Nuclear Information System (INIS)

    Ouda, S.M.

    2009-01-01

    Four strains of cellulolytic fungi (i.e Penicillium oxalicum, Aspergillus niger, Aspergillus terreus and Trichoderma longibrachiatum) were tested for the production of cellulolytic enzymes and antibiotic action. these fungi were cultured on Czapek Dox's media with different cellulosic substrates. A. terreus. exhibited the highest cellulolytic activity and the highest level of anti-bacterial activity against Staphylococcus aureus. and Escherichia Coli, Ultraviolet light as a mutagenic treatment for A.terreus was investigated. Two treated isolates U.30.12 and U.60.10 were obtained after the treatment at dose 30 and 60 min., respectively with a higher antibiotic activity in comparison with the wild isolate. A compound of fifteen carbon atom of terrecylic acid was isolated from ethyl acetate extract using spectroscopic analysis

  15. Molecular mechanisms involved in adaptive responses to radiation, UV light, and heat

    International Nuclear Information System (INIS)

    Takahashi, Akihisa; Ohnishi, Takeo

    2009-01-01

    Viable organisms recognize and respond to environmental changes or stresses. When these environmental changes and their responses by organisms are extreme, they can limit viability. However, organisms can adapt to these different stresses by utilizing different possible responses via signal transduction pathways when the stress is not lethal. In particular, prior mild stresses can provide some aid to prepare organisms for subsequent more severe stresses. These adjustments or adaptations for future stresses have been called adaptive responses. These responses are present in bacteria, plants and animals. The following review covers recent research which can help describe or postulate possible mechanisms which may be active in producing adaptive responses to radiation, ultraviolet light, and heat. (author)

  16. Photocatalytic activity of attapulgite–BiOCl–TiO2 toward degradation of methyl orange under UV and visible light irradiation

    International Nuclear Information System (INIS)

    Zhang, Lili; Zhang, Jiahui; Zhang, Weiguang; Liu, Jianquan; Zhong, Hui; Zhao, Yijiang

    2015-01-01

    Highlights: • Excellent photocatalyst was obtained by introducing BiOCl–TiO 2 onto attapulgite. • 100 mg L −1 methyl orange (MO) was totally decomposed under UV light within 70 min. • 92.6% of 10 mg L −1 MO was decomposed within 120 min under visible light. • ATT–BiOCl–TiO 2 show better activity than P 25 especially under visible light. • Mechanism of photocatalytic activity enhancement was identified. - Abstract: An environmental friendly composite photocatalyst with efficient UV and visible light activity has been synthesized by introducing BiOCl–TiO 2 hybrid oxide onto the surface of attapulgite (ATT) (denoted as ATT–BiOCl–TiO 2 ), using a simple in situ depositing technique. The obtained products were characterized by XRD, TEM, BET and UV–vis diffuse reflectance spectra measurements. Results showed that BiOCl–TiO 2 composite particles were successfully loaded onto attapulgite fibers' surface without obvious aggregation. The photocatalytic activity of ATT–BiOCl–TiO 2 was investigated by degradation of methyl orange under UV and visible light irradiation. It was found that 100 mg L −1 methyl orange was totally decomposed under UV light within 70 min and 92.57% of 10 mg L −1 methyl orange was decomposed under visible light within 120 min using ATT–BiOCl–TiO 2 as photocatalyst. These results were quite better than that of P 25 , especially under visible light irradiation. Possible mechanism for the enhancement was proposed

  17. Exploring the Inner Acceleration Region of Solar Wind: A Study Based on Coronagraphic UV and Visible Light Data

    Science.gov (United States)

    Bemporad, A.

    2017-09-01

    This work combined coronagraphic visible light (VL) and UV data to provide with an unprecedented view of the inner corona where the nascent solar wind is accelerated. The UV (H I Lyα) and VL (polarized brightness) images (reconstructed with SOHO/UVCS, LASCO, and Mauna Loa data) have been analyzed with the Doppler dimming technique to provide for the first time daily 2D images of the radial wind speed between 1 and 6 R ⊙ over 1 month of observations. Results show that both polar and equatorial regions are characterized at the base of the corona by plasma outflows at speeds > 100 km s-1. The plasma is then decelerated within ˜1.5 R ⊙ at the poles and ˜2.0 R ⊙ at the equator, where local minima of the expansion speeds are reached, and gently reaccelerated higher up, reaching speeds typical of fast and slow wind components. The mass flux is highly variable with latitude and time at the equator and more uniform and stable over the poles. The polar flow is asymmetric, with speeds above the south pole lower than those above the north pole. A correlation (anticorrelation) between the wind speed and its density is found below (above) ˜1.8 R ⊙. The 2D distribution of forces responsible for deceleration and reacceleration of solar wind is provided and interpreted in terms of Alfvén waves. These results provide a possible connection between small-scale outflows reported with other instruments at the base of the corona and bulk wind flows measured higher up.

  18. Graphitic-C(3)N(4)-hybridized TiO(2) nanosheets with reactive {001} facets to enhance the UV- and visible-light photocatalytic activity.

    Science.gov (United States)

    Gu, Liuan; Wang, Jingyu; Zou, Zhijuan; Han, Xijiang

    2014-03-15

    AnataseTiO(2)nanosheets with dominant {001} facets were hybridized with graphitic carbon nitride (g-C(3)N(4)) using a facile solvent evaporation method. On top of the superior photocatalytic performance of highly reactive {001} facets, the hybridization with g-C(3)N(4) is confirmed to further improve the reactivity through degrading a series of organic molecules under both UV- and visible-light irradiation. It is proposed that an effective charge separation between g-C(3)N(4) and TiO2 exists in the photocatalytic process, i.e., the transferring of photogenerated holes from the valence band (VB) of TiO(2) to the highest occupied molecular orbital (HOMO) of g-C(3)N(4), and the injecting of electrons from the lowest unoccupied molecular orbital (LUMO) of g-C(3)N(4) to the conduction band (CB) of TiO(2). Due to this synergistic effect, the enhancement of UV- and visible-light photoactivity over the hybrid is achieved. Furthermore, it has been revealed that holes were the main factor for the improved photoactivity under UV-light, while the OH radicals gained the predominance for degrading organic molecules under visible-light. Overall, this work would be significant for fabricating efficient UV-/visible-photocatalysts and providing deeper insight into the enhanced mechanisms of π-conjugated molecules hybridized semiconductors. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. CORONA-INDUCED PHOTOXIDATION OF ALCOHOLS AND HYDROCARBONS OVER TIO2 IN THE ABSENCE OF A UV LIGHT SOURCE - A NOVEL AND ENVIRONMENTALLY FRIENDLY METHOD FOR OXIDATION

    Science.gov (United States)

    Corona-induced photooxidation is a novel oxidation methodology for the efficient oxidation of alcohols and hydrocarbons utilizing the advantage of both the high oxidizing power of ozone formed in the reactor as well as the photooxidation capability of the UV light generated durin...

  20. Enhanced selective photocatalytic reduction of CO2 to CH4 over plasmonic Au modified g-C3N4 photocatalyst under UV-vis light irradiation

    Science.gov (United States)

    Li, Hailong; Gao, Yan; Xiong, Zhuo; Liao, Chen; Shih, Kaimin

    2018-05-01

    A series of Au-g-C3N4 (Au-CN) catalysts were prepared through a NaBH4-reduction method using g-C3N4 (CN) from pyrolysis of urea as precursor. The catalysts' surface area, crystal structure, surface morphology, chemical state, functional group composition and optical properties were characterized by X-ray diffraction, transmission electron microscope, X-ray photoelectron spectroscopy, ultraviolet visible (UV-vis) diffuse reflectance spectra, fourier transform infrared, photoluminescence and transient photocurrent analysis. The carbon dioxide (CO2) photoreduction activities under ultraviolet visible (UV-vis) light irradiation were significantly enhanced when gold (Au) was loaded on the surface of CN. 2Au-CN catalyst with Au to CN mole ratio of 2% showed the best catalytic activity. After 2 h UV-vis light irradiation, the methane (CH4) yield over the 2Au-CN catalyst was 9.1 times higher than that over the pure CN. The CH4 selectivity also greatly improved for the 2Au-CN compared to the CN. The deposited Au nanoparticles facilitated the separation of electron-hole pairs on the CN surface. Moreover, the surface plasmon resonance effect of Au further promoted the generation of hot electrons and visible light absorption. Therefore, Au loading significantly improved CO2 photoreduction performance of CN under UV-vis light irradiation.

  1. Enhanced photocatalytic activity for H2 evolution under irradiation of UV-vis light by Au-modified nitrogen-doped TiO2.

    Science.gov (United States)

    Zhao, Weirong; Ai, Zhuyu; Dai, Jiusong; Zhang, Meng

    2014-01-01

    Photocatalytic water splitting for hydrogen evolution is a potential way to solve many energy and environmental issues. Developing visible-light-active photocatalysts to efficiently utilize sunlight and finding proper ways to improve photocatalytic activity for H2 evolution have always been hot topics for research. This study attempts to expand the use of sunlight and to enhance the photocatalytic activity of TiO2 by N doping and Au loading. Au/N-doped TiO2 photocatalysts were synthesized and successfully used for photocatalytic water splitting for H2 evolution under irradiation of UV and UV-vis light, respectively. The samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), and photoelectrochemical characterizations. DRS displayed an extension of light absorption into the visible region by doping of N and depositing with Au, respectively. PL analysis indicated electron-hole recombination due to N doping and an efficient inhibition of electron-hole recombination due to the loaded Au particles. Under the irradiation of UV light, the photocatalytic hydrogen production rate of the as-synthesized samples followed the order Au/TiO2 > Au/N-doped TiO2 > TiO2 > N-doped TiO2. While under irradiation of UV-vis light, the N-TiO2 and Au/N-TiO2 samples show higher H2 evolution than their corresponding nitrogen-free samples (TiO2 and Au/TiO2). This inconsistent result could be attributed to the doping of N and the surface plasmonic resonance (SPR) effect of Au particles extending the visible light absorption. The photoelectrochemical characterizations further indicated the enhancement of the visible light response of Au/N-doped TiO2. Comparative studies have shown that a combination of nitrogen doping and Au loading enhanced the visible light response of TiO2 and increased the utilization of solar energy, greatly

  2. Enhanced photocatalytic activity for H2 evolution under irradiation of UV-vis light by Au-modified nitrogen-doped TiO2.

    Directory of Open Access Journals (Sweden)

    Weirong Zhao

    Full Text Available BACKGROUND PURPOSE: Photocatalytic water splitting for hydrogen evolution is a potential way to solve many energy and environmental issues. Developing visible-light-active photocatalysts to efficiently utilize sunlight and finding proper ways to improve photocatalytic activity for H2 evolution have always been hot topics for research. This study attempts to expand the use of sunlight and to enhance the photocatalytic activity of TiO2 by N doping and Au loading. METHODS: Au/N-doped TiO2 photocatalysts were synthesized and successfully used for photocatalytic water splitting for H2 evolution under irradiation of UV and UV-vis light, respectively. The samples were characterized using X-ray diffraction (XRD, transmission electron microscopy (TEM, X-ray photoelectron spectroscopy (XPS, UV-vis diffuse reflectance spectroscopy (DRS, photoluminescence spectroscopy (PL, and photoelectrochemical characterizations. RESULTS: DRS displayed an extension of light absorption into the visible region by doping of N and depositing with Au, respectively. PL analysis indicated electron-hole recombination due to N doping and an efficient inhibition of electron-hole recombination due to the loaded Au particles. Under the irradiation of UV light, the photocatalytic hydrogen production rate of the as-synthesized samples followed the order Au/TiO2 > Au/N-doped TiO2 > TiO2 > N-doped TiO2. While under irradiation of UV-vis light, the N-TiO2 and Au/N-TiO2 samples show higher H2 evolution than their corresponding nitrogen-free samples (TiO2 and Au/TiO2. This inconsistent result could be attributed to the doping of N and the surface plasmonic resonance (SPR effect of Au particles extending the visible light absorption. The photoelectrochemical characterizations further indicated the enhancement of the visible light response of Au/N-doped TiO2. CONCLUSION: Comparative studies have shown that a combination of nitrogen doping and Au loading enhanced the visible light response of

  3. Hyperfine structure and isotope shift of transitions in YbI using UV and deep-UV cw laser light and the angular distribution of fluorescence radiation

    NARCIS (Netherlands)

    Zinkstok, R.T.; van Duijn, E.J.; Witte, S.; Hogervorst, W.

    2002-01-01

    Using the third harmonic of a cw titanium:sapphire laser, the hyperfine structure (HFS) and isotope shift (IS) of three deep-UV transitions of neutral Yb have been measured for the first time. By exploiting the angular distribution of fluorescence radiation, accurate and complete results are

  4. Understanding the superior photocatalytic activity of noble metals modified titania under UV and visible light irradiation.

    Science.gov (United States)

    Bumajdad, Ali; Madkour, Metwally

    2014-04-28

    Although TiO2 is one of the most efficient photocatalysts, with the highest stability and the lowest cost, there are drawbacks that hinder its practical applications like its wide band gap and high recombination rate of the charge carriers. Consequently, many efforts were directed toward enhancing the photocatalytic activity of TiO2 and extending its response to the visible region. To head off these attempts, modification of TiO2 with noble metal nanoparticles (NMNPs) received considerable attention due to their role in accelerating the transfer of photoexcited electrons from TiO2 and also due to the surface plasmon resonance which induces the photocatalytic activity of TiO2 under visible light irradiation. This insightful perspective is devoted to the vital role of TiO2 photocatalysis and its drawbacks that urged researchers to find solutions such as modification with NMNPs. In a coherent context, we discussed here the characteristics which qualify NMNPs to possess a great enhancement effect for TiO2 photocatalysis. Also we tried to understand the reasons behind this effect by means of photoluminescence (PL) and electron paramagnetic resonance (EPR) spectra, and Density Functional Theory (DFT) calculations. Then the mechanism of action of NMNPs upon deposition on TiO2 is presented. Finally we introduced a survey of the behaviour of these noble metal NPs on TiO2 based on the particle size and the loading amount.

  5. Mutation spectrum produced on PBR322 by 8-Methoxypsoralen plus UV-A light

    International Nuclear Information System (INIS)

    Bauluz, C.; Vidania, R.

    1990-01-01

    The mutagenic effect of 8-MOP+UVA (PUVA treatment) on pBR322 has been analysed by determining the frequency of mutation in the tet gene and identifying the type and position of the mutations produced inside a 276 pb-fragment (Bam-H1-SalI) of the same gene. pBR322 DNA was irradiated with UVA light in the presence of increasing concentrations of 8-Methoxypsoralen (8-MOP). The number of psoralen adducts formed in pBR322 upon that treatment ranged from 0 to 10.7 adducts per plasmid molecule. Modified DNA samples were used to transform several strains of E. Coli (differing in their repair capacities), both in constitutive conditions and after sos pre-induction by 254 nm-irradiation of cells. Mutation frequencies in the tet gene showed to increase in the wild type and uvrA strains along with the number of psoralen adducts per plasmid molecule; higher mutation frequencies were found in cells that had been previously irradiated to induce the SOS expression. Mutant plasmids were isolated from ApRTcS colonies and sequenced by the method of Maxam and Gilbert. Mutations appeared to be unique in most of the cases and were always punctual, i.e. affecting only to one base pair. The relative positions of the mutations showed a high frequency of coincidence among the sequenced fragments, indicating the existence of several DNA regions with high probability to mutated ('hot spots'). (author)

  6. Competition for nitrogen between European beech and sycamore maple shifts in favour of beech with decreasing light availability.

    Science.gov (United States)

    Simon, Judy; Li, Xiuyuan; Rennenberg, Heinz

    2014-01-01

    Plant species use different strategies for maximizing growth and fitness under changing environmental conditions. At the ecosystem level, seedlings in particular compete with other vegetation components for light and nitrogen (N), which often constitute growth-limiting resources. In this study, we investigated the effect of light availability on the competition for N between seedlings of European beech and sycamore maple and analysed the consequences of this competition for the composition of N metabolites in fine roots. Our results show different strategies in N acquisition between beech and sycamore maple. Both species responded to reduced light availability by adapting their morphological and physiological traits with a decrease in biomass and net assimilation rate and an increase in specific leaf area and leaf area ratio. For beech seedlings, competition with sycamore maple led to a reduction in organic N uptake capacity. Reduced light availability led to a decrease in ammonium, but an increase in glutamine-N uptake capacity in sycamore maple. However, this response was stronger compared with that of beech and was accompanied by reduced growth. Thus, our results suggest better adaptation of N acquisition to reduced light availability in beech compared with sycamore maple seedlings.

  7. An investigation into UV light exposure as an experimental model for artificial aging on tensile strength and force delivery of elastomeric chain.

    Science.gov (United States)

    Wahab, Siti Waznah; Bister, Dirk; Sherriff, Martyn

    2014-02-01

    This study investigated the effect of ultraviolet type A light (UVA) exposure on the tensile properties of elastomeric chain. UVA light exposure was used as model for artificial aging, simulating prolonged storage of elastomeric chain. Tensile strength (n = 60) was measured after exposing Ormco, Forestadent and 3M chains to UVA light for 0, 2, 3, and 4 weeks. Force decay was measured (n = 60) using chain exposed for 5, 10, and 14 days. The chains were subsequently stretched at a constant distance and the resulting forces measured at 0, 1, 24 hours and 7, 14, 21, and 28 days. This test simulated a clinical scenario of pre-stretching and subsequent shortening of elastomeric chain. Tensile strength had statistically significant difference and was directly related to the duration of ultraviolet (UV) light exposure. Forestadent chain, which had the second highest value for the 'as received' product, showed the most consistent values over time with the lowest degradation. Ormco showed the lowest values for 'as received' as well as after UV exposure; 3M chain had the highest loss of tensile strength. Force decay was also significantly different. UV light exposure of 10 days or more appears to mark a 'watershed' between products: 3M had most survivors, Forestadent chain had some survivors, depending on the time the chain was stretched for. None of the Ormco product survived UV light exposure for more than 5 days. UVA light exposure may be used as a model for artificial aging as it reduces force delivery and tensile strength of exposed chains.

  8. UV Light-Assisted Synthesis of Highly Efficient Pd-Based Catalyst over NiO for Hydrogenation of o-Chloronitrobenzene.

    Science.gov (United States)

    Jiang, Weidong; Xu, Bin; Fan, Guangyin; Zhang, Kaiming; Xiang, Zhen; Liu, Xiaoqiang

    2018-04-14

    Supported Pd-based catalyst over active nickel oxide (NiO) was repared using the impregnation method companying with UV-light irradiation. Moreover, the catalytic performance of the obtained Pd-based catalysts was evaluated towards the hydrogenation of o -chloronitrobenzene ( o -CNB). Observations indicate that the as-prepared UV-irradiated Pd/NiO catalyst with a mole fraction 0.2% (0.2%Pd/NiO) has higher activity and selectivity in the o -CNB hydrogenation. Especially, UV-light irradiation played a positive role in the improvement of catalytic activity of 0.2%Pd/NiO catalyst, exhibiting an excess 11-fold activity superiority in contrast with non-UV-irradiated 0.2%Pd/NiO catalyst. In addition, it was investigated that effects of varied factors (i.e., reaction time, temperature, o -CNB/Pd ratio, Pd loading, hydrogen pressure) on the selective hydrogenation of ο -CNB catalyzed by UV-irradiated 0.2%Pd/NiO catalyst. Under the reaction conditions of 60 °C, 0.5 h, 1 MPa H₂ pressure, 100% conversion of o -CNB, and 81.1% o -CAN selectivity were obtained, even at high molar ratio (8000:1) of o -CNB to Pd.

  9. Deletion of epidermal Rac1 inhibits HPV-8 induced skin papilloma formation and facilitates HPV-8- and UV-light induced skin carcinogenesis.

    Science.gov (United States)

    Deshmukh, Jayesh; Pofahl, Ruth; Pfister, Herbert; Haase, Ingo

    2016-09-06

    Overexpression and increased activity of the small Rho GTPase Rac1 has been linked to squamous cell carcinoma of the epidermis and mucosa in humans. Targeted deletion of Rac1 or inhibition of Rac1 activity in epidermal keratinocytes reduced papilloma formation in a chemical skin carcinogenesis mouse model. However, a potential role of Rac1 in HPV- and UV-light induced skin carcinogenesis has not been investigated so far, solar UV radiation being an important carcinogen to the skin.To investigate this, we deleted Rac1 or modulated its activity in mice with transgenic expression of Human papilloma virus type-8 (HPV-8) in epidermal keratinocytes. Our data show that inhibition or deletion of Rac1 results in reduced papilloma formation upon UV-irradiation with a single dose, whereas constitutive activation of Rac1 strongly increases papilloma frequency in these mice. Surprisingly, we observed that, upon chronic UV-irradiation, the majority of mice with transgenic expression of HPV-8 and epidermis specific Rac1 deletion developed squamous cell carcinomas. Taken together, our data show that Rac1 exerts a dual role in skin carcinogenesis: its activation is, on one hand, required for HPV-8- and UV-light induced papilloma formation but, on the other, suppresses the development of squamous cell carcinomas.

  10. Decreased TK activity alters growth, yield and tolerance to low temperature and low light intensity in transgenic cucumber plants.

    Science.gov (United States)

    Bi, Huangai; Dong, Xubing; Wu, Guoxiu; Wang, Meiling; Ai, Xizhen

    2015-02-01

    Four CsTK antisense transgenic cucumber plants were obtained. Decreased TK activity decreased the photosynthetic rate, seed germination rate, growth yield, and the tolerance to low temperature and weak light stress. Transketolase (TK, EC 2.2.1.1) is a key enzyme in the photosynthetic carbon reduction cycle (Calvin cycle). A cDNA fragment (526 bp) encoding transketolase was cloned from cucumber plants (Cucumis sativa L. cv 'Jinyou 3') by RT-PCR. The antisense expression [(PBI-CsTK(-)] vector containing the CsTK gene fragment was constructed. The resulting plasmid was introduced into the cucumber inbred lines '08-1' using the agrobacterium-mediated method, and four antisense transgenic cucumber plants were obtained. Decreased CsTK expression either unaltered or slightly increased the mRNA abundance and activities of the other main enzymes in the Calvin cycle, however, it decreased the TK activity and net photosynthetic rate (Pn) in antisense transgenic cucumber leaves. Antisense plants showed decreases in the growth, ratio of female flowers and yield compared with the wild-type (WT) plants. The decrease in Pn, stomatal conductance (Gs), transpiration rate (Tr), photochemical efficiency (Fv/Fm) and actual photochemical efficiency of PSII (ΦPSII) and the increase in electrolyte leakage (EL) were greater in antisense transgenic plants than in WT plants under low temperature (5 °C) and low light intensity (100 μmol m(-2) s(-1)).

  11. Pretreatment with UV light renders the chromatin in human fibroblasts more susceptible to the DNA-damaging agents bleomycin, gamma radiation and 8-methoxypsoralen

    International Nuclear Information System (INIS)

    Ljungman, Mats

    1989-01-01

    Confluent human fibroblast cultures were pretreated with either 254 nm UV light (UV) or methyl methanesulphonate (MMS), incubated at 37 0 C and subsequently challenged on ice with bleomycin (BLM), gamma-radiation or 8-methoxy-psoralen (MOP). The resulting number of challenge-induced DNA damages (measured as DNA strand breaks or cross-links) were compared with the numbers induced in similarly challenged but non-pretreated control cells. It was found that the timing of the subsequent challenge of cells pretreated with UV did significantly affect the amount of induced DNA damage. When the challenging agents were administered after a 10-20 min incubation period following UV pretreatment, the amount of induced DNA damage was increased 50% over control cells. In contrast, the timing of the subsequent challenge of cells pretreated with MMS has no influence on the level of challenge-induced damage. It is hypothesized that UV-irradiated chromatin undergoes a time-dependent decondensation that renders it more susceptible to the induction of strand breaks and cross-links by BLM, gamma-radiation and MOP. A possible role for chromatin decondensation in UV-induced excision repair is discussed. (author)

  12. Synthesis, characterization and photocatalytic activity of WO3/TiO2 for NO removal under UV and visible light irradiation

    International Nuclear Information System (INIS)

    Luévano-Hipólito, E.; Martínez-de la Cruz, A.; López-Cuellar, E.; Yu, Q.L.; Brouwers, H.J.H.

    2014-01-01

    Samples with different proportions WO 3 /TiO 2 were prepared by co-precipitation method followed by a heat treatment. The samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), and adsorption–desorption N 2 isotherms (BET). The photocatalytic properties of WO 3 /TiO 2 samples were evaluated in the photo-oxidation reaction of nitric oxide (NO) under UV and visible light irradiation. The highest photocatalytic activity was observed in the WO 3 /TiO 2 sample with a composition of 80% mole of TiO 2 . Among the different substrates used for supporting the photocatalyst, the best results were reached over concrete and glass when it was exposed to UV and visible light irradiation, respectively. In overall, the photocatalytic efficiency of the synthesized materials was higher under UV than visible light irradiation. - Highlights: • WO 3 /TiO 2 prepared in simple way show high photocatalytic activity for NO removal. • The concrete was the best substrate to the performance of WO 3 /TiO 2 with UV radiation. • The glass was the best substrate to the performance of WO 3 /TiO 2 with visible radiation

  13. Synthesis, characterization and photocatalytic activity of WO{sub 3}/TiO{sub 2} for NO removal under UV and visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Luévano-Hipólito, E. [CIIDIT, Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Ciudad Universitaria, C.P. 66451 San Nicolás de los Garza, N.L. (Mexico); Martínez-de la Cruz, A., E-mail: azael.martinezdl@uanl.edu.mx [CIIDIT, Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Ciudad Universitaria, C.P. 66451 San Nicolás de los Garza, N.L. (Mexico); López-Cuellar, E. [CIIDIT, Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Ciudad Universitaria, C.P. 66451 San Nicolás de los Garza, N.L. (Mexico); Yu, Q.L.; Brouwers, H.J.H. [Department of the Built Environment, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands)

    2014-11-14

    Samples with different proportions WO{sub 3}/TiO{sub 2} were prepared by co-precipitation method followed by a heat treatment. The samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), and adsorption–desorption N{sub 2} isotherms (BET). The photocatalytic properties of WO{sub 3}/TiO{sub 2} samples were evaluated in the photo-oxidation reaction of nitric oxide (NO) under UV and visible light irradiation. The highest photocatalytic activity was observed in the WO{sub 3}/TiO{sub 2} sample with a composition of 80% mole of TiO{sub 2}. Among the different substrates used for supporting the photocatalyst, the best results were reached over concrete and glass when it was exposed to UV and visible light irradiation, respectively. In overall, the photocatalytic efficiency of the synthesized materials was higher under UV than visible light irradiation. - Highlights: • WO{sub 3}/TiO{sub 2} prepared in simple way show high photocatalytic activity for NO removal. • The concrete was the best substrate to the performance of WO{sub 3}/TiO{sub 2} with UV radiation. • The glass was the best substrate to the performance of WO{sub 3}/TiO{sub 2} with visible radiation.

  14. Optical anisotropy of polyimide and polymethacrylate containing photocrosslinkable chalcone group in the side chain under irradiation of a linearly polarized UV light

    CERN Document Server

    Choi, D H

    2002-01-01

    Photocrosslinkable soluble polyimide and polymethacrylate compound were synthesized for studying the optically induced anisotropy of the thin films. Chalcone group was introduced into the side chain unit of two polymers. We observed a photodimerization behavior between the double bonds in the chalcone group and an optical anisotropy of these materials by irradiation of a linearly polarized UV light (LPL). Optical anisotropy of the thin film was also investigated by using polarized UV absorption spectroscopy.The dynamic property of optical anisotropy in photoreactive polyimide was compared to that in polymethacrylate containing chalcone group in the side chain.

  15. Differential effects of near-UV and visible light on active transport and other membrane processes in Escherichia coli

    International Nuclear Information System (INIS)

    Sprott, G.D.; Martin, W.G.; Schneider, N.

    1976-01-01

    The effects of monochromatic near-UV and visible light on active transport and several other membrane processes in Escherichia coli were investigated. Using mercury lines at 366, 405, 435, 546 and 578 nm, large differential effects were observed. Transport systems with photosensitive initial rates of uptake were classified into three groups on the basis of wavelength dependence. Three, and possibly four photosensitizers may be involved; three active under aerobic conditions and the fourth in the absence of oxygen. Respiration rate exhibited the same sensitivity as one of the groups, suggesting that the active uptake of member amino acids (e.g. glycine) is largely dependent on oxidation energy. The photosensitivity of glycine transport at 405 nm was not the result of inhibition of the membrane-bound Ca-Mg adenosine triphosphates as shown using an isogenic mutant strain. Cell viability was not affected at the highly active wavelength, 405 nm. Photoeffects on transport of α-methylglucoside were minimal at 366 and 405 nm, contrasting to most of the amino acids investigated. The relative photosensitivity of respiration and several amino acid transport systems depended on carbon source. (author)

  16. UV light B-mediated inhibition of skin catalase activity promotes Gr-1+ CD11b+ myeloid cell expansion.

    Science.gov (United States)

    Sullivan, Nicholas J; Tober, Kathleen L; Burns, Erin M; Schick, Jonathan S; Riggenbach, Judith A; Mace, Thomas A; Bill, Matthew A; Young, Gregory S; Oberyszyn, Tatiana M; Lesinski, Gregory B

    2012-03-01

    Skin cancer incidence and mortality are higher in men compared with women, but the causes of this sex discrepancy remain largely unknown. UV light exposure induces cutaneous inflammation and neutralizes cutaneous antioxidants. Gr-1(+)CD11b(+) myeloid cells are heterogeneous bone marrow-derived cells that promote inflammation-associated carcinogenesis. Reduced activity of catalase, an antioxidant present in the skin, has been associated with skin carcinogenesis. We used the outbred, immune-competent Skh-1 hairless mouse model of UVB-induced inflammation and non-melanoma skin cancer to further define sex discrepancies in UVB-induced inflammation. Our results demonstrated that male skin had relatively lower baseline catalase activity, which was inhibited following acute UVB exposure in both sexes. Further analysis revealed that skin catalase activity inversely correlated with splenic Gr-1(+)CD11b(+) myeloid cell percentage. Acute UVB exposure induced Gr-1(+)CD11b(+) myeloid cell skin infiltration, which was inhibited to a greater extent in male mice by topical catalase treatment. In chronic UVB studies, we demonstrated that the percentage of splenic Gr-1(+)CD11b(+) myeloid cells was 55% higher in male tumor-bearing mice compared with their female counterparts. Together, our findings indicate that lower skin catalase activity in male mice may at least in part contribute to increased UVB-induced generation of Gr-1(+)CD11b(+) myeloid cells and subsequent skin carcinogenesis.

  17. The protective effect of some Thai plants and their bioactive compounds in UV light-induced skin carcinogenesis.

    Science.gov (United States)

    de Silva, Madhura B; Tencomnao, Tewin

    2018-05-02

    Skin cancer, represents a major public health concern. While the vast majority is non-melanoma skin cancers, melanomas are mostly responsible for mortality. Solar UVB radiation is mutagenic and carcinogenic. It is primarily responsible for both non-melanoma and melanoma skin cancers via excessive production of reactive oxygen species (ROS), which mediate changes in inflammation and immunity, and have been implicated in all three stages of skin cancer development. Due to their regulatory role in numerous functions of cells, signaling pathways are targets for chemoprevention. The current standards in melanoma therapy are targeted and combination therapies, which, albeit prolong survival responses, are still prone to development of drug resistance. To this extent, drugs of natural origin continue to spark great interest. Thailand has a rich biodiversity of indigenous flora, which have traditionally been used to treat a variety of pathologies. The active components in plant extracts that have medicinal properties, termed 'bioactive compounds,' are efficient chemopreventive agents due to their antioxidant, antimutagenic, anticarcinogenic, and carcinogen detoxification properties. Thai plants and their bioactive compounds have shown protective effects on UV light-induced skin cancer in different experimental models. This warrants further in vivo investigations and translation to clinical studies to determine efficacy and safety, for use as lead compounds in targeted/combination therapy or adjuvant therapy with existing regimes. Coupled with a strategy for prevention, this offers a promising outlook for protection against photocarcinogenesis. Copyright © 2018 Elsevier B.V. All rights reserved.

  18. Photoluminescence, afterglow and thermoluminescence in SrAl2O4:Eu2+,Dy3+ irradiated with blue and UV light

    International Nuclear Information System (INIS)

    Chernov, V.; Piters, T.M.; Melendrez, R.; Yen, W.M.; Cruz-Zaragoza, E.; Barboza-Flores, M.

    2007-01-01

    The luminescence in SrAl 2 O 4 :Eu 2+ ,Dy 3+ under continuous excitation is quite different from the 'standard' intra-ion photoluminescence (PL) and gradually grows during hundreds of seconds before reaching the saturation (photo-charging effect). In this work, we report the behavior of photo-charging effect under the blue and UV light irradiation at temperatures between 20 and 370 K, as well as afterglow (AG) and thermoluminescence (TL) observed after the irradiation termination. At 20 K the photo-charging effect is absent. With increasing temperature the photo-charging effect appears as a result of PL decreasing due to competitive trapping process with activation energy of 0.17 eV. The AG decay curves are described well by the Becquerel's law with the exponent close to 1. The AG decay time is about 10-50 s and practically does not depend on temperature. The TL glow curve exhibits at least seven partially overlapped peaks with maxima at 50, 65, 80, 155, 200, 250 and 290 K. The emission spectra of Eu 2+ consist of two bands at 450 and 520 nm. Both the bands are the same for the PL, AG and TL spectra, but their ratio depends on temperature and the luminescence type

  19. Influence of x-rays and UV-light on the presence of oncogene proteins in spleen cells of leukemic mice

    International Nuclear Information System (INIS)

    Popovic Hadzija, M.; Poljak Blazi, M.

    1996-01-01

    Proto-oncogenes are involved in growth, defferentiation and proliferation of normal cells, and in process of neoplastic transformation. In genome of normal cells, exist also tumor-suppressor genes, which contribute to cancer when they are inactivated. Those genes are target for carcinogenesis provoked by radiation. However, species specific genetic factors are important in determing which, if any, gene will be transformed by radiation. It is possible to presume that oncogenes are involved in the development of radioresistant phenotype of ML. Because of that, we examined the presence of c-myc protein in ML cells during the growth of ML and after the irradiation of these cells. Also, we examined the presence of tumor-suppressor protein p53, because inactivation or loss of p53 gene is in connection with transformation of cells. ML is strain specific for RFM mice. Spleen cells were tested 9 (nonterminal phase NTP) or 12 days (terminal phase TP) after inoculation of ML. Cells from NTP were also irradiate with x-rays or UV-light. C-myc protein expresse 74.98% spleen cells of healthy RFM mice. Wild type of p53 protein was detected in 60% of these cells, but mp53 was found in only 5.3% of cells. These results could be explained by the role of c-myc and p53 proteins in regulation of biologic processes. A few spleen cells of NTP expressed c-myc (15%) and mp53 (9.6%) proteins. But, in the same phase higher expressions of wp53 protein (30.5%) was found. On the other hand, the number of c-myc positive cells in TP of leukemia explanation lies in connection of c-myc protein and process of programmed cell death (apoptosis). During growth of ML the number of mp53 positive cells increased (to 47.8%), but wp53 positive cells decreased (to13.4%9). Both types of irradiation provoked strong activation of cellular c-myc gene in ML cells of NTP. We found about 95% c-myc positive cells after x-rays and 93% after UV-light

  20. Comparative study on toxicity of ZnO and TiO2 nanoparticles on Artemia salina: effect of pre-UV-A and visible light irradiation.

    Science.gov (United States)

    Bhuvaneshwari, M; Sagar, Bhawana; Doshi, Siddharth; Chandrasekaran, N; Mukherjee, Amitava

    2017-02-01

    This study evaluated the toxicity potential of ZnO and TiO 2 nanoparticles under pre-UV-A irradiation and visible light condition on Artemia salina. The nanoparticle suspension was prepared in seawater medium and exposed under pre-UV-A (0.23 mW/cm 2 ) and visible light (0.18 mW/cm 2 ) conditions. The aggregation profiles of both nanoparticles (NPs) and dissolution of ZnO NPs under both irradiation conditions at various kinetic intervals (1, 24, 48 h) were studied. The 48-h LC 50 values were found to be 27.62 and 71.63 mg/L for ZnO NPs and 117 and 120.9 mg/L for TiO 2 NPs under pre-UV-A and visible light conditions. ZnO NPs were found to be more toxic to A. salina as compared to TiO 2 NPs. The enhanced toxicity was observed under pre-UV-A-irradiated ZnO NPs, signifying its phototoxicity. Accumulation of ZnO and TiO 2 NPs into A. salina depends on the concentration of particles and type irradiations. Elimination of accumulated nanoparticles was also evident under both irradiation conditions. Other than ZnO NPs, the dissolved Zn 2+ also had a significant effect on toxicity and accumulation in A. salina. Increased catalase (CAT) activity in A. salina indicates the generation of oxidative stress due to NP interaction. Thus, this study provides an understanding of the toxicity of photoreactive ZnO and TiO 2 NPs as related to the effects of pre-UV-A and visible light irradiation.

  1. Gene activation by UV light, fungal elicitor or fungal infection in Petroselinum crispum is correlated with repression of cell cycle-related genes

    International Nuclear Information System (INIS)

    Logemann, E.; Wu ShengCheng; Schröder, J.; Schmelzer, E.; Somssich, I.E.; Hahlbrock, K.

    1995-01-01

    The effects of UV light or fungal elicitors on plant cells have so far been studied mostly with respect to defense-related gene activation. Here, an inverse correlation of these stimulatory effects with the activities of several cell cycle-related genes is demonstrated. Concomitant with the induction of flavonoid biosynthetic enzymes in UV-irradiated cell suspension cultures of parsley (Petroselinum crispum), total histone synthesis declined to about half the initial rate. A subclass of the histone H3 gene family was selected to demonstrate the close correlation of its expression with cell division, both in intact plants and cultured cells. Using RNA-blot and run-on transcription assays, it was shown that one arbitrarily selected subclass of each of the histone H2A, H2B, H3 and H4 gene families and of the genes encoding a p34cdc2 protein kinase and a mitotic cyclin were transcriptionally repressed in UV-irradiated as well as fungal elicitor-treated parsley cells. The timing and extent of repression differed between the two stimuli; the response to light was more transient and smaller in magnitude. These differential responses to light and elicitor were inversely correlated with the induction of phenylalanine ammonia-lyase, a key enzyme of phenylpropanoid metabolism. Essentially the same result was obtained with a defined oligopeptide elicitor, indicating that the same signaling pathway is responsible for defense-related gene activation and cell cycle-related gene repression. A temporary (UV light) or long-lasting (fungal elicitor) cessation of cell culture growth is most likely due to an arrest of cell division which may be a prerequisite for full commitment of the cells to transcriptional activation of full commitment of the cells to transcriptional activation of pathways involved in UV protection or pathogen defense. This conclusion is corroborated by the observation that the histone H3 mRNA level greatly declined around fungal infection sites in young parsley

  2. CSF neurofilament light chain is elevated in OMS (decreasing with immunotherapy) and other pediatric neuroinflammatory disorders.

    Science.gov (United States)

    Pranzatelli, Michael R; Tate, Elizabeth D; McGee, Nathan R; Verhulst, Steven J

    2014-01-15

    Using a panel of seven brain cell-specific biomarkers in cerebrospinal fluid (CSF), pediatric opsoclonus-myoclonus syndrome (OMS) (n=234) was compared to pediatric non-inflammatory neurological controls (n=84) and other inflammatory neurological disorders (OIND) (n=44). Only CSF NFL was elevated in untreated OMS versus controls (+83%). It was 87% higher in OIND than in OMS. On combination treatment with front-loaded ACTH, IVIg, rituximab, median CSF NFL decreased by 60% to control levels. These biochemical data suggest neuronal/axonal injury in some children with OMS without indicators of astrogliosis, and reduction on sufficient immunotherapy. Copyright © 2013 Elsevier B.V. All rights reserved.

  3. Decrease in fMRI brain activation during working memory performed after sleeping under 10 lux light.

    Science.gov (United States)

    Kang, Seung-Gul; Yoon, Ho-Kyoung; Cho, Chul-Hyun; Kwon, Soonwook; Kang, June; Park, Young-Min; Lee, Eunil; Kim, Leen; Lee, Heon-Jeong

    2016-11-09

    The aim of this study was to investigate the effect of exposure to dim light at night (dLAN) when sleeping on functional brain activation during a working-memory tasks. We conducted the brain functional magnetic resonance imaging (fMRI) analysis on 20 healthy male subjects. All participants slept in a polysomnography laboratory without light exposure on the first and second nights and under a dim-light condition of either 5 or 10 lux on the third night. The fMRI scanning was conducted during n-back tasks after second and third nights. Statistical parametric maps revealed less activation in the right inferior frontal gyrus (IFG) after exposure to 10-lux light. The brain activity in the right and left IFG areas decreased more during the 2-back task than during the 1- or 0-back task in the 10-lux group. The exposure to 5-lux light had no significant effect on brain activities. The exposure to dLAN might influence the brain function which is related to the cognition.

  4. Photocatalytic degradation of cylindrospermopsin under UV-A, solar and visible light using TiO2. Mineralization and intermediate products.

    Science.gov (United States)

    Fotiou, Theodora; Triantis, Theodoros; Kaloudis, Triantafyllos; Hiskia, Anastasia

    2015-01-01

    Cyanobacteria (blue-green algae) are considered an important water quality problem, since several genera can produce toxins, called cyanotoxins that are harmful to human health. Cylindrospermopsin (CYN) is an alkaloid-like potent cyanotoxin that has been reported in water reservoirs and lakes worldwide. In this paper the removal of CYN from water by UV-A, solar and visible light photocatalysis was investigated. Two different commercially available TiO2 photocatalysts were used, i.e., Degussa P25 and Kronos-vlp7000. Complete degradation of CYN was achieved with both photocatalysts in 15 and 40 min under UV-A and 40 and 120 min under solar light irradiation, for Degussa P25 and Kronos vlp-7000 respectively. Experiments in the absence of photocatalysts showed that direct photolysis was negligible. Under visible light irradiation only the Kronos vlp-7000 which is a visible light activated catalyst was able to degrade CYN. A number of intermediates were identified and a complete degradation pathway is proposed, leading to the conclusion that hydroxyl radical attack is the main mechanism followed. TOC and inorganic ions (NO2-, NO3-, SO4(2-) and NH4+) determinations suggested that complete mineralization of CYN was achieved under UV-A in the presence of Degussa P25. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. Study of the UV Light Conversion of Feruloyl Amides from Portulaca oleracea and Their Inhibitory Effect on IL-6-Induced STAT3 Activation.

    Science.gov (United States)

    Hwang, Joo Tae; Kim, Yesol; Jang, Hyun-Jae; Oh, Hyun-Mee; Lim, Chi-Hwan; Lee, Seung Woong; Rho, Mun-Chual

    2016-06-30

    Two new feruloyl amides, N-cis-hibiscusamide (5) and (7'S)-N-cis-feruloylnormetanephrine (9), and eight known feruloyl amides were isolated from Portulaca oleracea L. and the geometric conversion of the ten isolated feruloyl amides by UV light was verified. The structures of the feruloyl amides were determined based on spectroscopic data and comparison with literature data. The NMR data revealed that the structures of the isolated compounds showed cis/trans-isomerization under normal laboratory light conditions. Therefore, cis and trans-isomers of feruloyl amides were evaluated for their convertibility and stability by UV light of a wavelength of 254 nm. After 96 h of UV light exposure, 23.2%-35.0% of the cis and trans-isomers were converted to trans-isomers. Long-term stability tests did not show any significant changes. Among all compounds and conversion mixtures collected, compound 6 exhibited the strongest inhibition of IL-6-induced STAT3 activation in Hep3B cells, with an IC50 value of 0.2 μM. This study is the first verification of the conversion rates and an equilibrium ratio of feruloyl amides. These results indicate that this natural material might provide useful information for the treatment of various diseases involving IL-6 and STAT3.

  6. Pre-oxidation of low-density polyethylene (LDPE) by ultraviolet light (UV) promotes enhanced degradation of LDPE in soil.

    Science.gov (United States)

    Tribedi, Prosun; Dey, Samrat

    2017-11-09

    Polyethylene represents nearly 64% of all the synthetic plastics produced and are mainly used for domestic and industrial applications. Their extensive use poses a serious environmental threat because of their non-biodegradable nature. Among all the polyethylene remediation strategies, in situ bioremediation happens to be the safest and efficient one. In the current study, efforts had been given to compare the extent of LDPE degradation under UV-treated and UV-untreated conditions by soil microcosm. Landfill soil was collected and UV-treated and UV-untreated LDPE were added separately to the soil following incubation under similar conditions. Electron microscopic images as well as the weight loss and the tensile strength results clearly revealed that UV-treated LDPE showed better degradation than the non-treated ones in soil. To elucidate the mechanism of this enhanced biodegradation, the bond spectra of differentially treated LDPE were analyzed by FTIR. The results obtained from bond spectra studies revealed that UV treatment increases both carbonyl and terminal double-bond index of the LDPE, thereby making it highly susceptible for microbial degradation. Moreover, incubation of UV-treated LDPE with soil favors better adherence of metabolically active and significantly higher number of microorganisms on it. Taken together, all these results demonstrate the higher microbial association and their better metabolic potential to the UV-treated LDPE that lead to enhanced degradation of the LDPE by the soil microorganisms.

  7. Skin hardening effect in patients with polymorphic light eruption: comparison of UVB hardening in hospital with a novel home UV-hardening device.

    Science.gov (United States)

    Franken, S M; Genders, R E; de Gruijl, F R; Rustemeyer, T; Pavel, S

    2013-01-01

    An effective prophylactic treatment of patients with polymorphic light eruption (PLE) consists of repeated low, gradually increasing exposures to UVB radiation. This so-called UV(B) hardening induces better tolerance of the skin to sunlight. SunshowerMedical company (Amsterdam) has developed an UV (B) source that can be used during taking shower. The low UV fluence of this apparatus makes it an interesting device for UV hardening. In a group of PLE patients, we compared the effectiveness of the irradiation with SunshowerMedical at home with that of the UVB treatment in the hospital. The PLE patients were randomized for one of the treatments. The hospital treatment consisted of irradiations with broad-band UVB (Waldmann 85/UV21 lamps) twice a week during 6 weeks. The home UV-device was used each day with the maximal irradiation time of 6 min. The outcome assessment was based on the information obtained from patients' dermatological quality of life (DLQI) questionnaires, the ability of both phototherapies to reduce the provocation reaction and from the patients' evaluation of the long-term benefits of their phototherapies. Sixteen patients completed treatment with SunshowerMedical and thirteen completed treatment in hospital. Both types of phototherapy were effective. There was a highly significant improvement in DLQI with either treatment. In most cases, the hardening reduced or even completely suppressed clinical UV provocation of PLE. The patients using SunshowerMedical at home were, however, much more content with the treatment procedure than the patients visiting the dermatological units. Both treatments were equally effective in the induction of skin tolerance to sunlight in PLE patients. However, the home treatment was much better accepted than the treatment in the hospital. © 2011 The Authors. Journal of the European Academy of Dermatology and Venereology © 2011 European Academy of Dermatology and Venereology.

  8. Chemical and UV Mutagenesis.

    Science.gov (United States)

    Bose, Jeffrey L

    2016-01-01

    The ability to create mutations is an important step towards understanding bacterial physiology and virulence. While targeted approaches are invaluable, the ability to produce genome-wide random mutations can lead to crucial discoveries. Transposon mutagenesis is a useful approach, but many interesting mutations can be missed by these insertions that interrupt coding and noncoding sequences due to the integration of an entire transposon. Chemical mutagenesis and UV-based random mutagenesis are alternate approaches to isolate mutations of interest with the potential of only single nucleotide changes. Once a standard method, difficulty in identifying mutation sites had decreased the popularity of this technique. However, thanks to the recent emergence of economical whole-genome sequencing, this approach to making mutations can once again become a viable option. Therefore, this chapter provides an overview protocol for random mutagenesis using UV light or DNA-damaging chemicals.

  9. Chromosomal analysis in mouse eggs fertilized in vitro with sperm exposed to ultraviolet light (UV) and methyl and ethyl methanesulfonate (MMS and EMS)

    International Nuclear Information System (INIS)

    Matsuda, Y.; Tobari, I.

    1988-01-01

    Chromosome aberrations were analyzed at the first-cleavage metaphase of mouse eggs fertilized in vitro with sperm exposed to ultraviolet light (UV) as well as to methyl and ethyl methanesulfonate (MMS and EMS). The frequencies of chromosome aberrations markedly increased with dose of UV as well as with concentration of MMS and EMS. In the UV-irradiation group, the frequency of chromosome-type aberrations was much higher than that of chromatid-type aberrations. About 90% of chromosome aberrations observed in the eggs following MMS and EMS treatment to sperm were chromosome type in which the frequency of chromosome fragments was the highest. The effects of UV on the induction of chromosome aberrations were clearly potentiated by post-treatment incubation of fertilized eggs in the presence of Ara-C or caffeine, but the effects of MMS and EMS were not pronounced by post-treatment of Ara-C or caffeine. The results indicate a possibility that UV damage induced in mouse sperm DNA is reparable in the eggs during the period between the entry of sperm into the egg cytoplasm and the first-cleavage metaphase. 35 refs.; 5 figs.; 4 tabs

  10. Aligned energy-level design for decreasing operation voltage of tandem white organic light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Chih-Hao, E-mail: chc@saturn.yzu.edu.tw [Department of Photonics Engineering, Yuan Ze University, Chung-Li 32003, Taiwan, ROC (China); Wu, Zih-Jyun; Liang, Yi-Hu; Chang, Yu-Shuo; Chiu, Chuan-Hao; Tai, Cheng-Wei [Department of Photonics Engineering, Yuan Ze University, Chung-Li 32003, Taiwan, ROC (China); Chang, Hsin-Hua, E-mail: hhua3@mail.vnu.edu.tw [Department of Electro-Optical Engineering, Vanung University, Chung-Li 32061, Taiwan, ROC (China)

    2013-12-02

    In general, organic light-emitting devices (OLEDs) need to operate at higher current density levels to ensure an ample light flux. However, stressed operation will result in poor performance and limited device lifetime. Recently, a tandem structure has been proposed as a pivotal technique to meet the stringent lighting requirements for OLED commercialization, with a research focus on decreasing the concomitant higher operation voltage. Driving two connected emission units (EMUs) in a tandem structure often requires more than twice the driving voltage for a single EMU. This study investigates bipolar host materials and their effective employment in fabricating tandem white phosphorescent OLEDs (PhOLEDs). In addition, the design of a mechanism to align the energy level between the hole transport layer/emitting layer is shown to effectively mitigate operational voltages. In sharp contrast to devices using a unipolar host material, we demonstrate that the turn-on voltage of blue PhOLEDs could be decreased from 3.8 V to 2.7 V through utilizing a bipolar host. Furthermore, applying the proposed techniques to tandem white PhOLEDs produces a luminance of 10{sup 3} cd/m{sup 2} by a 10.1 V driving voltage. - Highlights: • The matched energy level between the hole transport/emitting layer lowers voltages. • Multiple conduction dopants were used to investigate charge generation layer. • Two-color emitters were used to quantify the charge generation strength.

  11. Aligned energy-level design for decreasing operation voltage of tandem white organic light-emitting diodes

    International Nuclear Information System (INIS)

    Chang, Chih-Hao; Wu, Zih-Jyun; Liang, Yi-Hu; Chang, Yu-Shuo; Chiu, Chuan-Hao; Tai, Cheng-Wei; Chang, Hsin-Hua

    2013-01-01

    In general, organic light-emitting devices (OLEDs) need to operate at higher current density levels to ensure an ample light flux. However, stressed operation will result in poor performance and limited device lifetime. Recently, a tandem structure has been proposed as a pivotal technique to meet the stringent lighting requirements for OLED commercialization, with a research focus on decreasing the concomitant higher operation voltage. Driving two connected emission units (EMUs) in a tandem structure often requires more than twice the driving voltage for a single EMU. This study investigates bipolar host materials and their effective employment in fabricating tandem white phosphorescent OLEDs (PhOLEDs). In addition, the design of a mechanism to align the energy level between the hole transport layer/emitting layer is shown to effectively mitigate operational voltages. In sharp contrast to devices using a unipolar host material, we demonstrate that the turn-on voltage of blue PhOLEDs could be decreased from 3.8 V to 2.7 V through utilizing a bipolar host. Furthermore, applying the proposed techniques to tandem white PhOLEDs produces a luminance of 10 3 cd/m 2 by a 10.1 V driving voltage. - Highlights: • The matched energy level between the hole transport/emitting layer lowers voltages. • Multiple conduction dopants were used to investigate charge generation layer. • Two-color emitters were used to quantify the charge generation strength

  12. Light curve solutions and study of roles of magnetic fields in period variations of the UV Leo system

    Directory of Open Access Journals (Sweden)

    D Manzoori

    2009-12-01

    Full Text Available The solutions of photometric BV light curves for the Algol like system UV Leo were obtained using Wilson-Devinney code. The physical and orbital parameters along with absolute dimensions of the system were determined. It has been found that to best fit the V light curve of the system, assumptions of three dark spots were necessary two on the secondary and one on the primary. The absolute visual magnitudes (Mv of the individual components i.e., primary and secondary were estimated to 4.41 and 4.43, respectively, through the color curve analysis. The period analysis of the system presented elsewhere, indicated a cyclic period change of 12 yr duration, which was attributed to magnetic activity cycle, as a main cause of period variation in the system, through the Applegate mechanism. To verify the Applegate model I preformed calculations of some related parameters barrowed from Apllegate and Kalimeris. Values of all the calculated parameters were in accordance to those obtained for similar systems by Applegate. The differential magnitudes Δ B and Δ V, along with corresponding values of Δ(B-V color index. The cyclic variations in brightness are quite clear. There are three predictions of Applegate's theory concerning effects of cyclic magnetic changes on the period variations, which can be checked through the observations, these are as follows: I The long term variations in mean brightness (at outside of eclipses and cyclic changes of orbital period, vary with the same period. II The active star gets bluer as it gets brightened and/or the brightness and color variations are to be in phase. III Changes in luminosity due to changes in quadrupole moment should be of the order 0.1 mag. All the above mentioned predictions of Applegate’s theory are verified. These results combined with cyclic character of P(E presented elsewhere and also consistency of parameters which are obtained in this paper, led me to conclude that one the main causes of period

  13. Enhanced UV-Visible Light Photocatalytic Activity by Constructing Appropriate Heterostructures between Mesopore TiO₂ Nanospheres and Sn₃O₄ Nanoparticles.

    Science.gov (United States)

    Hu, Jianling; Tu, Jianhai; Li, Xingyang; Wang, Ziya; Li, Yan; Li, Quanshui; Wang, Fengping

    2017-10-19

    Novel TiO₂/Sn₃O₄ heterostructure photocatalysts were ingeniously synthesized via a scalable two-step method. The impressive photocatalytic abilities of the TiO₂/Sn₃O₄ sphere nanocomposites were validated by the degradation test of methyl orange and •OH trapping photoluminescence experiments under ultraviolet (UV) and visible light irradiation, respectively. Especially under the visible light, the TiO₂/Sn₃O₄ nanocomposites demonstrated a superb photocatalytic activity, with 81.2% of methyl orange (MO) decomposed at 30 min after irradiation, which greatly exceeded that of the P25 (13.4%), TiO₂ (0.5%) and pure Sn₃O₄ (59.1%) nanostructures. This enhanced photocatalytic performance could be attributed to the mesopore induced by the monodispersed TiO₂ cores that supply sufficient surface areas and accessibility to reactant molecules. This exquisite hetero-architecture facilitates extended UV-visible absorption and efficient photoexcited charge carrier separation.

  14. Role of cloned carotenoid genes expressed in Escherichia coli in protecting against inactivation by near-UV light and specific phototoxic molecules

    International Nuclear Information System (INIS)

    Tuveson, R.W.; Larson, R.A.; Kagan, J.

    1988-01-01

    Genes controlling carotenoid synthesis were cloned from Erwinia herbicola and expressed in an Escherichia coli strain. Carotenoids protect against high fluences of near-UV (NUV; 320 to 400 nm) but not against far-UV (200-300 nm). Protection of E. coli cells was not observed following treatment with either psoralen or 8-methoxypsoralen plus NUV. However, significant protection of cells producing carotenoids was observed with three photosensitizing molecules activated by NUV (alpha-terthienyl, harmine, and phenylheptatriyne) which are thought to have the membrane as an important lethal target. Protection of carotenoid-producing cells against inactivation was not observed with acridine orange plus visible light but was seen with toluidine blue O plus visible light

  15. Study on the resistance of haloferax radiotolerans, an extreme Halophilic archaebacterium from Uromia lake against ultraviolet (UV) light and 60Co gamma-rays

    International Nuclear Information System (INIS)

    Asgarni, E.; Shirzad, M.; Soudi, M. R.; Shahmohammadi, H. R.; Falsafi, T.

    2006-01-01

    In this work, the capacity of an extreme halophilic archaebacterium, isolated from Uromia lake, Haloferax radiotolerans to withstand the lethal effects of ultraviolet light (UV),and 60 Co r-rays has been studied. The resistibility of this organism against the DNA-damaging agents was evaluated by calculating of the survival fractions at different dose rates of W and 60 Co r-rays radiations and compared with those of Escherichia coli B/r (a radioresistant strain of E. coli). D 37 values for Haloferax radiotolerans and E. coli B/r were 23 1, and 9 J/m 2 , respectively, by exposure to the UV light. They were 645, and 99 Gy, respectively, by exposure to 60 Co r-rays. Against these agents, Haloferax radiotolerans shows much more resistance compare to that of E. coli B/r. This is categorized as the first report of resistibility in the member of Archaea

  16. Effect oof some antibiotics, disinfectants, and UV light on vability of vegetative cells and spores of C1. perfringend type A

    International Nuclear Information System (INIS)

    Rymkiewicz, D.

    1977-01-01

    Cells and spores of 40 strains of C1. perfringens type A, pathogenic for guinea pigs, were tested for resistance to antibiotics, drugs, disinfectants used in surgery and in bacteriological laboratories, and UV light. No correlation was found between thermoresistance of spores and their resistance to other bactericidal agents. Among the common disinfectants, iodine solution showed strong bactericidal and sporostatic activity. Good bactericidal effect was also obtained by combined action of Vescodin and UV light. Drug resistance of C1. perfringens type A strains changed clearly in the past 10 years. Strains inducing gangrene became resistant to penicillin and tetracyclines, which hitherto were commonly applied. Ampicilin can now be recommended, as the antibiotic with strong bactericidal and sporostatic action. (author)

  17. 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

  18. Recyclable UV and visible light photocatalytically active amorphous TiO2 doped with M (III) ions (M = Cr and Fe)

    International Nuclear Information System (INIS)

    Buddee, Supat; Wongnawa, Sumpun; Sirimahachai, Uraiwan; Puetpaibool, Walailak

    2011-01-01

    Research highlights: → The low photocatalytic activity of amorphous TiO2 was enhanced by doping with Cr(III) or Fe(III) ions. → The doped catalysts performed close to P25 under UV light and better with visible light. → The doped catalysts can be recycled. - Abstract: Samples of amorphous TiO 2 doped with Cr(III) and Fe(III), designated as Cr-TiO 2 and Fe-TiO 2 , were prepared via modified impregnation method. The resulting products were characterized by X-ray diffraction, scanning electron microscopy, specific surface area by the Brunauer, Emmett and Teller method, UV-vis absorption and diffuse reflectance spectroscopy, and electron spin resonance spectroscopy. Experimental results revealed that the concentrations of dopants under studied, from 0.05 to 0.2 mol%, had no effect on the phase of products. The band gap energies shifted from 3.28 eV in the undoped amorphous TiO 2 to 2.50 eV and 2.86 eV for Fe-TiO 2 and Cr-TiO 2 , respectively. The doped amorphous TiO 2 showed photocatalytic activities under both UV and visible light with optimal results at 0.1 mol% dopants. Under UV irradiation, the 0.1 mol% doped samples decolorized methylene blue solutions to the same extent as the commercial TiO 2 samples (P25 and anatase) in 5 h. Under visible light, the doped samples decolorized dye solutions in 12 h while the commercial ones were much less active. The used catalysts can be recycled many times without any special treatment.

  19. High-sensitivity detection of polysaccharide using phosphodiesters quaternary ammonium salt as probe by decreased resonance light scattering.

    Science.gov (United States)

    Chen, Zhanguang; Liu, Guoliang; Chen, Maohuai; Wu, Mingyao

    2009-07-15

    Phosphodiesters quaternary ammonium salt (PQAS) displayed quite intense light scattering in aqueous solution under the optimum condition. In addition, the resonance light scattering (RLS) signal of PQAS was remarkably decreased after adding trace amount polysaccharide with the maximum peak located at 391 nm. It was found that the decreased RLS intensity of the PQAS-PPGL system (DeltaI(RLS)) was in proportion to PPGL concentration in the range of 0.1-30 ng mL(-1), with a lower detection limit of 0.05 ng mL(-1). Based on this rare decreased RLS phenomenon, the novel method of the determination of purified polysaccharide of Gracilaria Lemaneiformis (PPGL) at nanogram level was proposed in this contribution. The proposed approach was used to determine purified polysaccharide extracted from Gracilaria Lemaneiformis with satisfactory results. Compared with the reported polysaccharide assays, this proposed method has good selectivity, high sensitivity and is especially simple and convenient. Moreover, the mechanism of the reaction between PQAS and polysaccharide was investigated by RLS, fluorescence, and fluorescence lifetime spectra.

  20. Photocatalytic degradation and mineralization of microcystin-LR under UV-A, solar and visible light using nanostructured nitrogen doped TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Triantis, T.M.; Fotiou, T. [Laboratory of Catalytic - Photocatalytic Processes (Solar Energy - Environment), Institute of Physical Chemistry, National Center for Scientific Research ' Demokritos' , Neapoleos 25, 15310 Agia Paraskevi, Attiki (Greece); Kaloudis, T. [Organic Micropollutants Laboratory, Athens Water Supply and Sewerage Company (EYDAP SA), WTP Aharnon, Menidi (Greece); Kontos, A.G.; Falaras, P. [Laboratory of Photo-redox Conversion and Storage of Solar Energy, Institute of Physical Chemistry, National Center for Scientific Research ' Demokritos' , Neapoleos 25, 15310 Agia Paraskevi, Attiki (Greece); Dionysiou, D.D.; Pelaez, M. [Environmental Engineering and Science Program, School of Energy, Environmental, Biological and Medical Engineering, University of Cincinnati, OH 45221-0012 (United States); Hiskia, A., E-mail: hiskia@chem.demokritos.gr [Laboratory of Catalytic - Photocatalytic Processes (Solar Energy - Environment), Institute of Physical Chemistry, National Center for Scientific Research ' Demokritos' , Neapoleos 25, 15310 Agia Paraskevi, Attiki (Greece)

    2012-04-15

    Highlights: Black-Right-Pointing-Pointer N-TiO{sub 2} exhibited effective degradation of MC-LR under UV-A, solar and visible light. Black-Right-Pointing-Pointer Complete photocatalytic mineralization of MC-LR was achieved under UV-A and solar light. Black-Right-Pointing-Pointer The organic nitrogen is mainly released as ammonium and nitrate ions. - Abstract: In an attempt to face serious environmental hazards, the degradation of microcystin-LR (MC-LR), one of the most common and more toxic water soluble cyanotoxin compounds released by cyanobacteria blooms, was investigated using nitrogen doped TiO{sub 2} (N-TiO{sub 2}) photocatalyst, under UV-A, solar and visible light. Commercial Degussa P25 TiO{sub 2}, Kronos and reference TiO{sub 2} nanopowders were used for comparison. It was found that under UV-A irradiation, all photocatalysts were effective in toxin elimination. The higher MC-LR degradation (99%) was observed with Degussa P25 TiO{sub 2} followed by N-TiO{sub 2} with 96% toxin destruction after 20 min of illumination. Under solar light illumination, N-TiO{sub 2} nanocatalyst exhibits similar photocatalytic activity with that of commercially available materials such as Degussa P25 and Kronos TiO{sub 2} for the destruction of MC-LR. Upon irradiation with visible light Degussa P25 practically did not show any response, while the N-TiO{sub 2} displayed remarkable photocatalytic efficiency. In addition, it has been shown that photodegradation products did not present any significant protein phosphatase inhibition activity, proving that toxicity is proportional only to the remaining MC-LR in solution. Finally, total organic carbon (TOC) and inorganic ions (NO{sub 2}{sup -}, NO{sub 3}{sup -} and NH{sub 4}{sup +}) determinations confirmed that complete photocatalytic mineralization of MC-LR was achieved under both UV-A and solar light.

  1. An efficient visible and UV-light-activated B-N-codoped TiO{sub 2} photocatalytic film for solar depollution prepared via a green method

    Energy Technology Data Exchange (ETDEWEB)

    Xu Qingchi; Zhang Yan; He Ziming [Nanyang Technological University, School of Chemical and Biomedical Engineering (Singapore); Loo, Say Chye Joachim, E-mail: joachimloo@ntu.edu.sg [Nanyang Technological University, School of Materials Science and Engineering (Singapore); Tan, Timothy Thatt Yang, E-mail: tytan@ntu.edu.sg [Nanyang Technological University, School of Chemical and Biomedical Engineering (Singapore)

    2012-08-15

    This work reports an efficient visible and UV-light-activated boron and nitrogen codoped TiO{sub 2} porous film prepared via a 'green' and direct coating approach. Such photocatalyst is highly promising for solar depollution application due to its efficient photocatalytic activities in both visible and UV spectrum. The preparation method avoids the use of organic solvents, which are usually more expensive and hazardous compared with water. Using stearic acid as the model organic pollutant, the visible-light photocatalytic activity of optimized porous B-N-codoped TiO{sub 2} film (p-3B-N-TiO{sub 2}) is 3 times higher than that of porous N-doped TiO{sub 2} (p-N-TiO{sub 2}) film, while its UV photocatalytic activity is almost double that of p-N-TiO{sub 2} film and comparable to that of porous TiO{sub 2}. The enhancement in photocatalytic activity is attributed to higher surface area due to the porous structure, improved visible-light absorption attributed to interstitially substituted boron atoms, and coexistence of boron and nitrogen dopants which may reduce Ti{sup 3+} recombination centers.

  2. Physicochemcial characteristic of CdS-anchored porous WS2 hybrid in the photocatalytic degradation of crystal violet under UV and visible light irradiation

    Science.gov (United States)

    Vattikuti, S. V. Prabhakar; Ngo, Ich-Long; Byon, Chan

    2016-11-01

    In this work, we report the synthesis of CdS-incorporated porous WS2 by a simple hydrothermal method. The structural, morphological, and optical properties of the samples were examined by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FTIR), high resolution X-ray photoelectron spectroscopy (XPS) and UV-visible spectrometry. The photocatalytic activities were established for degradation of crystal violet (CV) under UV and visible light irradiation. The CdS-incorporated porous WS2 hybrid demonstrated high photocatalytic activity for degradation of CV pollutant compared to pure CdS nanoparticles and porous WS2 sheets. This result implies that the CdS-incorporated porous WS2 promoted more electron-hole pair transformation under UV and visible light irradiation. This significant enhancement of photocatalytic efficiency of CdS-incorporated porous WS2 photocatalyst under visible light can be ascribed to the presence of CdS nanospheres on the meshed-like WS2 sheets which potentially improves absorption in the visible range enabled by surface plasmon resonance effect of CdS nanospheres. The photostability and reusability of the CdS-porous WS2 were examined through recycling experiments.

  3. An efficient visible and UV-light-activated B–N-codoped TiO2 photocatalytic film for solar depollution prepared via a green method

    International Nuclear Information System (INIS)

    Xu Qingchi; Zhang Yan; He Ziming; Loo, Say Chye Joachim; Tan, Timothy Thatt Yang

    2012-01-01

    This work reports an efficient visible and UV-light-activated boron and nitrogen codoped TiO 2 porous film prepared via a “green” and direct coating approach. Such photocatalyst is highly promising for solar depollution application due to its efficient photocatalytic activities in both visible and UV spectrum. The preparation method avoids the use of organic solvents, which are usually more expensive and hazardous compared with water. Using stearic acid as the model organic pollutant, the visible-light photocatalytic activity of optimized porous B–N-codoped TiO 2 film (p-3B–N–TiO 2 ) is 3 times higher than that of porous N-doped TiO 2 (p-N–TiO 2 ) film, while its UV photocatalytic activity is almost double that of p-N–TiO 2 film and comparable to that of porous TiO 2 . The enhancement in photocatalytic activity is attributed to higher surface area due to the porous structure, improved visible-light absorption attributed to interstitially substituted boron atoms, and coexistence of boron and nitrogen dopants which may reduce Ti 3+ recombination centers.

  4. Effect of an umuC-mutation on the SOS-response in E.coli cells exposed to UV-light and γ-radiation

    International Nuclear Information System (INIS)

    Komova, O.V.; Candiano, E.S.; Krasavin, E.A.

    1999-01-01

    Kinetics dependences of the SOS-induction in E.coli cells of wild type and deficient in umuC gene exposed to UV and γ-rays were analyzed. In the presence of UmuC protein SOS-induction was 3 -- 5.5 times lower and delayed for about 30 minutes after both UV and γ-rays. It was shown that the decrease of the SOS-induction in wild type cells irradiated by UV was due to more effective elimination of the photolesions from DNA by excision repair system. UmuCD-dependent inhibition of DNA replication was discussed as a possible mechanism allowing additional time for error-free repair. (author)

  5. Survival of the fittest before the beginning of life: selection of the first oligonucleotide-like polymers by UV light

    Directory of Open Access Journals (Sweden)

    Cherepanov Dmitry A

    2003-05-01

    Full Text Available Abstract Background A key event in the origin of life on this planet has been formation of self-replicating RNA-type molecules, which were complex enough to undergo a Darwinian-type evolution (origin of the "RNA world". However, so far there has been no explanation of how the first RNA-like biopolymers could originate and survive on the primordial Earth. Results As condensation of sugar phosphates and nitrogenous bases is thermodynamically unfavorable, these compounds, if ever formed, should have undergone rapid hydrolysis. Thus, formation of oligonucleotide-like structures could have happened only if and when these structures had some selective advantage over simpler compounds. It is well known that nitrogenous bases are powerful quenchers of UV quanta and effectively protect the pentose-phosphate backbones of RNA and DNA from UV cleavage. To check if such a protection could play a role in abiogenic evolution on the primordial Earth (in the absence of the UV-protecting ozone layer, we simulated, by using Monte Carlo approach, the formation of the first oligonucleotides under continuous UV illumination. The simulations confirmed that UV irradiation could have worked as a selective factor leading to a relative enrichment of the system in longer sugar-phosphate polymers carrying nitrogenous bases as UV-protectors. Partial funneling of the UV energy into the condensation reactions could provide a further boost for the oligomerization. Conclusion These results suggest that accumulation of the first polynucleotides could be explained by their abiogenic selection as the most UV-resistant biopolymers.

  6. Uniform and pitting corrosion events induced by SCN- anions on Al alloys surfaces and the effect of UV light

    International Nuclear Information System (INIS)

    Amin, Mohammed A.

    2011-01-01

    The influence of the alloying elements on the uniform and pitting corrosion processes of Al-6061, Al-4.5%Cu, Al-7.5%Cu, Al-6%Si and Al-12%Si alloys was studied in 0.50 M KSCN solution at 25 o C. Open-circuit potential, Tafel polarization, linear polarization resistance (LPR) and ICP-AES measurements were used to study the uniform corrosion process on the surfaces of the tested alloys. Cyclic polarization, potentiostatic current-time transients and impedance techniques were employed for pitting corrosion studies. Obtained results were compared with pure Al. Passivation kinetics of the tested Al samples were also studied as a function of applied potential, [SCN - ] and sample composition by means of potentiostatic current transients. The induction time, after which the growth of stable pits occurs, decreased with increasing applied potential and [SCN - ]. Regarding to uniform corrosion, alloyed Cu was found to enhance the corrosion rate, while alloyed Si suppressed it. Alloying elements of the tested samples diminished pitting attack to an extent depending on the percentage of the alloying element in the sample. Among the investigated materials, Al-Si alloys exhibited the highest corrosion resistance towards uniform and pitting corrosion processes in KSCN solutions. The passive and dissolution behaviour of Al was also studied under the conditions of continuous illumination (300-450 nm) based on cyclic polarization and potentiostatic techniques. The incident photons had a little influence on pit initiation and a marked effect on pit growth. These explained in terms of a photo-induced modification of the passive film formed on the anode surface, which render it more resistant to pitting. The effects of UV photons energy and period of illumination on the morphology of the pitted surfaces were also studied.

  7. UV light-induced mutability in Salmonella strains containing the umuDC or the mucAB operon

    International Nuclear Information System (INIS)

    Herrera, G.; Urios, A.; Aleixandre, V.; Blanco, M.

    1988-01-01

    Multicopy plasmids carrying either the umuDC operon of Escherichia coli or its analog mucAB operon, were introduced into Ames Salmonella strains in order to analyze the influence of UmuDC and MucAB proteins on repair and mutability after UV irradiation. It was found that in uvr + bacteria, plasmid pICV80:mucAB increased the frequency of UV-induced His + revertants whereas pSE117:umuDC caused a smaller increase in UV mutagenesis. In ΔuvrB bacteria, the protective role of pSE117 against UV killing was weak, and there was a great reduction in the mutant yield. In contrast, in these cells, pICV80 led to a large increase in both cell survival and mutation frequency. These results suggest that in Salmonella, as in E. coli, MucAB proteins mediate UV mutagenesis more efficiently than UmuDC proteins do. Plasmid pICV84:umuD + C - significantly increased UV mutagenesis of TA2659:ΔuvrB cells whereas in them, pICV77:mucA + B - had no effect on mutability indicating the presence in Salmonella TA2659 of a gene functionally homologous to umuC. 18 refs.; 1 figure; 3 tabs

  8. Plasmonic Titania Photo catalysts Active under UV and Visible-Light Irradiation: Influence of Gold Amount, Size, and Shape

    International Nuclear Information System (INIS)

    Kowalska, E.; Rau, S.; Kowalska, E.; Kowalska, E.; Ohtani, B.

    2012-01-01

    Plasmonic titania photo catalysts were prepared by titania modification with gold by photo deposition. It was found that for smaller amount of deposited gold (≤ 0.1 wt%), anatase presence and large surface area were beneficial for efficient hydrogen evolution during methanol dehydrogenation. After testing twelve amounts of deposited gold on large rutile titania, the existence of three optima for 0.5, 2 and >6 wt% of gold was found during acetic acid degradation. Under visible light irradiation, in the case of small gold NPs deposited on fine anatase titania, the dependence of photo activity on gold amount was parabolic, and large gold amount (2 wt%), observable as an intensively coloured powder, caused photo activity decrease. While for large gold NPs deposited on large rutile titania, the dependence represented cascade increase, due to change of size and shape of deposited gold with its amount increase. It has been thought that spherical/hemispherical shape of gold NPs, in comparison with rod-like ones, is beneficial for higher level of photo activity under visible light irradiation. For all tested systems and regardless of deposited amount of gold, each rutile Au/TiO 2 photo catalyst of large gold and titania NPs exhibited much higher photo activity than anatase Au/TiO 2 of small gold and titania NPs

  9. Determination of photo-catalytic activity of un-doped and Mn-doped TiO2 anatase powders on acetaldehyde under UV and visible light

    International Nuclear Information System (INIS)

    Papadimitriou, Vassileios C.; Stefanopoulos, Vassileios G.; Romanias, Manolis N.; Papagiannakopoulos, Panos; Sambani, Kyriaki; Tudose, Valentin; Kiriakidis, George

    2011-01-01

    Titanium dioxide (TiO 2 ) photocatalytic powder materials doped with various levels of manganese (Mn) were synthesized to be used as additives to wall painting in combating indoor and outdoor air pollution. The heterogeneous photocatalytic degradation of gaseous acetaldehyde (CH 3 CHO) on Mn–TiO 2 surfaces under ultraviolet and visible (UV/Vis) irradiation was investigated, by employing the Photochemical Static Reactor coupled with Fourier-Transformed Infrared spectroscopy (PSR/FTIR) technique. Experiments were performed by exposing acetaldehyde (∼ 400 Pa) and synthetic air mixtures (∼ 1.01 × 10 5 Pa total pressure) on un-doped TiO 2 and doped with various levels of Mn (0.1–33% mole percentage) under UV and visible irradiation at room temperature. Photoactivation was initiated using either UV or visible light sources with known emission spectra. Initially, the photo-activity of CH 3 CHO under the above light sources, and the physical adsorption of CH 3 CHO on Mn–TiO 2 samples in the absence of light were determined prior to the photocatalytic experiments. The photocatalytic loss of CH 3 CHO on un-doped TiO 2 and Mn–TiO 2 samples in the absence and presence of UV or visible irradiation was measured over a long time period (≈ 60 min), to evaluate their relative photocatalytic activity. The gaseous photocatalytic end products were also determined using absorption FTIR spectroscopy. Carbon dioxide (CO 2 ) was identified as the main photocatalysis product. It was found that 0.1% Mn–TiO 2 samples resulted in the highest photocatalytic loss of CH 3 CHO under visible irradiation. This efficiency was drastically diminished at higher levels of Mn doping (1–33%). The CO 2 yields were the highest for 0.1% Mn–TiO 2 samples under UV irradiation, in agreement with the observed highest CH 3 CHO decomposition rates. It was demonstrated that low-level (0.1%) doping of TiO 2 with Mn results in a significant increase of their photocatalytic activity in the visible

  10. Photoreactivation of ultraviolet light-induced damage in cultured fish cells as revealed by increased colony forming ability and decreased content of pyrimidine dimers

    International Nuclear Information System (INIS)

    Shima, A.; Ikenaga, M.; Egami, N.

    1981-01-01

    Cultured cells derived from a goldfish were irradiated with 254 nm ultraviolet light. Cell survival and splitting of pyrimidine dimers after photoreactivation treatment with white fluorescent lamps were examined by colony forming ability and by a direct dimer assay, respectively. When UV-irradiated (5 J/m 2 ) cells were illuminated by photoreactivating light, cell survival was enhanced up to a factor of 9(40 min) followed by a decline after prolonged exposures. Exposure of UV-irradiated (15 J/m 2 ) cells to radiation from white fluorescent lamps reduced the amounts of thymine-containing dimers in a photoreactivating fluence dependent manner, up to about 60% reduction at 120 min exposure. Keeping UV-irradiated cells in the dark for up to 120 min did not affect either cell survival or the amount of pyrimidine dimers in DNA, indicating that there were not detectable levels of a dark-repair system in the cells under our conditions. Correlation between photoreactivation of colony forming ability and photoreactivation of the pyrimidine dimers was demonstrated, at least at relatively low fluences of photoreactivating light. (author)

  11. Photoreactivation of ultraviolet light-induced damage in cultured fish cells as revealed by increased colony forming ability and decreased content of pyrimidine dimers

    Energy Technology Data Exchange (ETDEWEB)

    Shima, A. (Shiga University of Medical Science, Otsu (Japan)); Ikenaga, M. (Osaka Univ. (Japan). Faculty of Medicine); Nikaido, O.; Takebe, H. (Kyoto Univ. (Japan)); Egami, N. (Tokyo Univ. (Japan). Faculty of Science)

    1981-03-01

    Cultured cells derived from a goldfish were irradiated with 254 nm ultraviolet light. Cell survival and splitting of pyrimidine dimers after photoreactivation treatment with white fluorescent lamps were examined by colony forming ability and by a direct dimer assay, respectively. When UV-irradiated (5 J/m/sup 2/) cells were illuminated by photoreactivating light, cell survival was enhanced up to a factor of 9(40 min) followed by a decline after prolonged exposures. Exposure of UV-irradiated (15 J/m/sup 2/) cells to radiation from white fluorescent lamps reduced the amounts of thymine-containing dimers in a photoreactivating fluence dependent manner, up to about 60% reduction at 120 min exposure. Keeping UV-irradiated cells in the dark for up to 120 min did not affect either cell survival or the amount of pyrimidine dimers in DNA, indicating that there were not detectable levels of a dark-repair system in the cells under our conditions. Correlation between photoreactivation of colony forming ability and photoreactivation of the pyrimidine dimers was demonstrated, at least at relatively low fluences of photoreactivating light.

  12. Effects of garlic on cellular doubling time and DNA strand breaks caused by UV light and BPL, enhanced with catechol and TPA

    International Nuclear Information System (INIS)

    Baturay, N.Z.; Gayle, F.; Liu, S.; Kreidinger, C.

    1995-01-01

    3T3 cell cultures were exposed to UV light and Beta-Propiolactone. Neoplastic cell transformation (TF) was demonstrated after concurrent addition of catechol, or repeated addition of TPA. Addition of garlic to all fluences/concentrations of the carcinogen/cocarcinogen/promoter groups reduced the number of transformed foci/dish by at least 40%. Since the cell cycle is prolonged following exposure to carcinogens, it is likely the cell requires a longer time to repair this damage. The doubling time (DT) was extended from 12 to 36 hrs. when cells were exposed to BPL and from 12 o 28 hrs. when cells were exposed to 3.0J/M2/sec. If an anticarcinogenic compound is also added, it is reasonable to assume that the cell cycle may be further elongated. The cell cycle, denoted by DT was lengthened from 12 to 47 hrs and from 12 to 86 hrs for BPL and UVC, respectively. The extensions occurred in a dope dependent manner. The concentrations of the cocarcinogen and promoter remained constant throughout the experiment. When strand breaks were determined at the same dose sequences, by alkaline elution, more repair was seen with garlic where the lowest and middle doses of BPL were used and almost no decrease in % DNA eluted was seen with UVC exposed cells. With catechol, there was a two-fold decrease in % DNA eluted at the lowest and middle fluences. When TPA was added, all three fluences of UVC showed more than a threefold decrease in % DNA eluted. BPS with both TPA and catechol, again showed a reduction in strand breaks only low and middle doses. Both a direct-acting alkylating agent, BPL, and a physical carcinogen, UVC, were homogeneously affected, in terms of doubling time, but not when strand break repair was examined. A separate mechanism may be responsible for repair, and the mechanism associated with combinations of physical carcinogen enhancing agents combined with some non-carcinogens may be more profoundly affected by some natural products

  13. Photo-electrocatalytic activity of TiO2 nanotubes prepared with two-step anodization and treated under UV light irradiation

    Directory of Open Access Journals (Sweden)

    Mohamad Mohsen Momeni

    2016-01-01

    Full Text Available To improve the photo-catalytic degradation of salicylic acid, we reported the fabrication of ordered TiO2 nanotube arrays by a simple and effective two-step anodization method and then these TiO2 nanotubes treated in a methanol solution under UV light irradiation. The TiO2 nanotubes prepared in the two-step anodization process showed better photo-catalytic activity than TiO2 nanotubes prepared in one-step anodization process. Also, compared with TiO2 nanotubes without the UV pretreatment, the TiO2 nanotubes pretreated in a methanol solution under UV light irradiation exhibited significant enhancements in both photocurrent and activity. The treated TiO2 nanotubes exhibited a 5-fold enhancement in photocurrent and a 2.5-fold increase in the photo-catalytic degradation of salicylic acid. Also the effect of addition of persulfate and periodate on the photo-catalytic degradation of salicylic acid were investigated. The results showed that the degradation efficiency of salicylic acid increased with increasing persulfate and periodate concentrations. These treated TiO2 nanotubes are promising candidates for practical photochemical reactors.

  14. High photocatalytic activity of hierarchical SiO2@C-doped TiO2 hollow spheres in UV and visible light towards degradation of rhodamine B.

    Science.gov (United States)

    Zhang, Ying; Chen, Juanrong; Hua, Li; Li, Songjun; Zhang, Xuanxuan; Sheng, Weichen; Cao, Shunsheng

    2017-10-15

    Ongoing research activities are targeted to explore high photocatalytic activity of TiO 2 -based photocatalysts for the degradation of environmental contaminants under UV and visible light irradiation. In this work, we devise a facile, cost-effective technique to in situ synthesize hierarchical SiO 2 @C-doped TiO 2 (SCT) hollow spheres for the first time. This strategy mainly contains the preparation of monodisperse cationic polystyrene spheres (CPS), sequential deposition of inner SiO 2 , the preparation of the sandwich-like CPS@SiO 2 @CPS particles, and formation of outer TiO 2 . After the one-step removal of CPS templates by calcination at 450°C, hierarchical SiO 2 @C-doped TiO 2 hollow spheres are in situ prepared. The morphology, hierarchical structure, and properties of SCT photocatalyst were characterized by TEM. SEM, STEM Mapping, BET, XRD, UV-vis spectroscopy, and XPS. Results strongly confirm the carbon doping in the outer TiO 2 lattice of SCT hollow spheres. When the as-synthesized SCT hollow spheres were employed as a photocatalyst for the degradation of Rhodamine B under visible-light and ultraviolet irradiation, the SCT photocatalyst exhibits a higher photocatalytic activity than commercial P25, effectively overcoming the limitations of poorer UV activity for many previous reported TiO 2 -based photocatalysts due to doping. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. A new on-axis micro-spectrophotometer for combining Raman, fluorescence and UV/Vis absorption spectroscopy with macromolecular crystallography at the Swiss Light Source

    International Nuclear Information System (INIS)

    Pompidor, Guillaume; Dworkowski, Florian S. N.; Thominet, Vincent; Schulze-Briese, Clemens; Fuchs, Martin R.

    2013-01-01

    The new version MS2 of the in situ on-axis micro-spectrophotometer at the macromolecular crystallography beamline X10SA of the Swiss Light Source supports the concurrent acquisition of Raman, resonance Raman, fluorescence and UV/Vis absorption spectra along with diffraction data. The combination of X-ray diffraction experiments with optical methods such as Raman, UV/Vis absorption and fluorescence spectroscopy greatly enhances and complements the specificity of the obtained information. The upgraded version of the in situ on-axis micro-spectrophotometer, MS2, at the macromolecular crystallography beamline X10SA of the Swiss Light Source is presented. The instrument newly supports Raman and resonance Raman spectroscopy, in addition to the previously available UV/Vis absorption and fluorescence modes. With the recent upgrades of the spectral bandwidth, instrument stability, detection efficiency and control software, the application range of the instrument and its ease of operation were greatly improved. Its on-axis geometry with collinear X-ray and optical axes to ensure optimal control of the overlap of sample volumes probed by each technique is still unique amongst comparable facilities worldwide and the instrument has now been in general user operation for over two years

  16. Comparative studies on the degradation of aqueous 2-chloroaniline by O3 as well as by UV-light and γ-rays in the presence of ozone

    International Nuclear Information System (INIS)

    Winarno, Ermin Katrin; Getoff, Nikola

    2002-01-01

    Chlorinated anilines are frequently used in the industry as starting materials for chemical synthesis. Hence, such compounds can occur as pollutants in waste waters. In the present study 2-chloroaniline (2-ClA) was selected as the representative model for this class of compounds. The objectives of the work concerned 2-ClA degradation in water by ozonation as well as by photolysis (UV-light of 254 nm) and radiolysis (γ-rays) in the presence of ozone. In all three series of experiments, the same amount ozone was passed through the 2-ClA solution at pH=6.9 during the treatment. The degradation process was followed as a function of the action time and by chemical analysis of the major products. Based on the actinometry of the monochromatic UV-light (λ=254 nm, E=4.88 eV/hν) and dosimetry data, the obtained degradation yields and products by the three series of experiments are compared. It was established that the synergic effect of γ-rays and ozone leads to the most efficient degradation of 2-ClA, followed by UV/O 3 -combination and pure ozonation. The same sequence is also observed by cleavage of the Cl-atom. The formation of the other major products: ammonia, formaldehyde, oxalic acid and the total yield of carboxylic acids depend on the media. Probable reaction mechanisms are suggested for explanation of the experimental results

  17. DNA sequence analysis of the mutational specificity of u.v. light in the SUP4-o gene of yeast

    International Nuclear Information System (INIS)

    Kunz, B.A.; Mis, J.R.A.; Pierce, M.K.; Giroux, C.N.

    1987-01-01

    Mutations induced in the SUP4-o gene of Saccharomyces cerevisiae by u.v. irradiation have been characterized. DNA sequence analysis of 120 mutants revealed that u.v. induced all types of base substitutions, although transitions, in particular G:C → A:T events predominated. In addition, a small number of single base pair deletions and double mutations, occurring in tandem or separated by a few base pairs, were recovered. The base pair substitutions were not distributed randomly in the SUP4-o gene and, with one exception, were all located at sites of adjacent pyrimidines, suggesting they were targeted by u.v. photolesions. A substantial fraction of the mutations were detected at hotspots for u.v. mutagenesis. The majority of changes occurred at the 3' base of dipyrimidine sequences where both cyclobutane dimers and [6-4]-photoproducts could form. Approximately one-third of the induced base substitutions were found at potential pyrimidine dimer sites where [6-4]-photoproducts would be expected to occur rarely. Possible origins of the induced mutations and the role of cyclobutane dimers as premutational u.v. lesions in yeast are considered. (author)

  18. Resistance of 3T3 mouse cells to UV light in relation to excision and transfer of dimers to daughter strands

    Energy Technology Data Exchange (ETDEWEB)

    Menck, C F.M.; Meneghini, R [Sao Paulo Univ. (Brazil). Inst. de Quimica

    1982-04-01

    Mouse cells (3T3 line) and human fibroblasts are equally sensitive to UV light. At fluences of 2.0-2.5 J/m/sup 2/ mouse cells excise only 20% of the pyrimidine dimers as compared to 80% excised by human fibroblasts. This fluence allows 37% survival in both cases. Hence, mouse cells are more resistant to the same burden of unexcised dimers. The reason for this increased tolerance to dimers does not seem to be due to a recombinational mechanism, as judged by the fact that only ca. 5% of the dimers are transferred from parental to daughter strands. The transfer of dimers was measured by the Micrococcus luteus UV endonuclease assay, irradiating cells at G/sub 1/ to avoid artifacts arising from introduction of dimers in nascent strands. The possibility of other mechanisms being involved in the process of tolerance to DNA lesions is discussed.

  19. A new on-axis micro-spectrophotometer for combining Raman, fluorescence and UV/Vis absorption spectroscopy with macromolecular crystallography at the Swiss Light Source.

    Science.gov (United States)

    Pompidor, Guillaume; Dworkowski, Florian S N; Thominet, Vincent; Schulze-Briese, Clemens; Fuchs, Martin R

    2013-09-01

    The combination of X-ray diffraction experiments with optical methods such as Raman, UV/Vis absorption and fluorescence spectroscopy greatly enhances and complements the specificity of the obtained information. The upgraded version of the in situ on-axis micro-spectrophotometer, MS2, at the macromolecular crystallography beamline X10SA of the Swiss Light Source is presented. The instrument newly supports Raman and resonance Raman spectroscopy, in addition to the previously available UV/Vis absorption and fluorescence modes. With the recent upgrades of the spectral bandwidth, instrument stability, detection efficiency and control software, the application range of the instrument and its ease of operation were greatly improved. Its on-axis geometry with collinear X-ray and optical axes to ensure optimal control of the overlap of sample volumes probed by each technique is still unique amongst comparable facilities worldwide and the instrument has now been in general user operation for over two years.

  20. Photocatalytic performance of Sn-doped and undoped TiO2 nanostructured thin films under UV and vis-lights

    International Nuclear Information System (INIS)

    Arpac, E.; Sayilkan, F.; Asiltuerk, M.; Tatar, P.; Kiraz, Nadir; Sayilkan, H.

    2007-01-01

    Sn-doped and undoped nano-TiO 2 particles have been synthesized by hydrotermal process without solvent at 200 deg. C in 1 h. Nanostructure-TiO 2 based thin films have been prepared on glass substrate by spin-coating technique. The structure, surface morphology and optical properties of the thin films and the particles have been investigated by element analysis and XRD, SEM, BET and UV-vis-NIR techniques. The photocatalytic performance of the films were tested for degradation of Malachite Green dye in solution under UV and vis-lights. The results showed that (a) hydrothermally synthesized nano-TiO 2 particles are fully anatase crystalline form and are easily dispersed in water, (b) the coated surfaces have nearly super-hydrophilic properties and (c) the doping of transition metal ion efficiently improved the photocatalytic performance of the TiO 2 thin film

  1. A new on-axis micro-spectrophotometer for combining Raman, fluorescence and UV/Vis absorption spectroscopy with macromolecular crystallography at the Swiss Light Source

    Science.gov (United States)

    Pompidor, Guillaume; Dworkowski, Florian S. N.; Thominet, Vincent; Schulze-Briese, Clemens; Fuchs, Martin R.

    2013-01-01

    The combination of X-ray diffraction experiments with optical methods such as Raman, UV/Vis absorption and fluorescence spectroscopy greatly enhances and complements the specificity of the obtained information. The upgraded version of the in situ on-axis micro-spectrophotometer, MS2, at the macromolecular crystallography beamline X10SA of the Swiss Light Source is presented. The instrument newly supports Raman and resonance Raman spectroscopy, in addition to the previously available UV/Vis absorption and fluorescence modes. With the recent upgrades of the spectral bandwidth, instrument stability, detection efficiency and control software, the application range of the instrument and its ease of operation were greatly improved. Its on-axis geometry with collinear X-ray and optical axes to ensure optimal control of the overlap of sample volumes probed by each technique is still unique amongst comparable facilities worldwide and the instrument has now been in general user operation for over two years. PMID:23955041

  2. Luminescent Properties of Sr4Si3O8Cl4:Eu2+, Bi3+ Phosphors for Near UV InGaN-Based Light-Emitting-Diodes

    Directory of Open Access Journals (Sweden)

    Wangqing Shen

    2015-12-01

    Full Text Available Sr4Si3O8Cl4 co-doped with Eu2+, Bi3+ were prepared by the high temperature reaction. The structure and luminescent properties of Sr4Si3O8Cl4:Eu2+, Bi3+ were investigated. With the introduction of Bi3+, luminescent properties of these phosphors have been optimized. Compared with Sr3.90Si3O8Cl4:0.10Eu2+, the blue-green phosphor Sr3.50Si3O8Cl4:0.10Eu2+, 0.40Bi3+ shows stronger blue-green emission with broader excitation in near-UV range. Bright blue-green light from the LED means this phosphor can be observed by the naked eye. Hence, it may have an application in near UV LED chips.

  3. Tricolor emission Ca3Si2O7:Ln (Ln=Ce, Tb, Eu) phosphors for near-UV white light-emitting-diode

    International Nuclear Information System (INIS)

    Mao, Zhi-yong; Zhu, Ying-chun; Gan, Lin; Zeng, Yi; Xu, Fang-fang; Wang, Yang; Tian, Hua; Li, Jian; Wang, Da-jian

    2013-01-01

    Tricolor emission in a same Ca 3 Si 2 O 7 host with independent Ln (Ln=Ce 3+ , Eu 2+ , Tb 3+ ) dopants is demonstrated to construct a near-UV white light emitting diode (LED). The luminescence properties and thermal quenching properties, as well as the applications in near-UV white LED are investigated. These phosphors show typical blue, red, and green, three-basal-color, luminescence in the CIE chromaticity diagram for Ce 3+ , Eu 2+ and Tb 3+ dopants, respectively. Thermal quenching properties show that the luminescence thermal stability strongly depends on the different dopant types; better thermal quenching property of Ce 3+ and Tb 3+ is recorded in comparison with that of Eu 2+ . The white LED prototype fabricated with near-UV chip and as-prepared tricolor phosphors exhibits acceptable CIE chromaticity coordinates (0.32, 0.30) with a CCT of 6000 K and a CRI of 87, indicating the potential application of Ca 3 Si 2 O 7 :Ln phosphors in near-UV white LED. - Highlights: ► Tricolor Ca 3 Si 2 O 7 : Ln phosphors were demonstrated to construct near-UV white LED. ► Eu 2+ doped Ca 3 Si 2 O 7 red-emitting phosphor was confirmed by this work once again. ► Thermal quenching properties for Ca 3 Si 2 O 7 :Ln phosphors were reported for the first time. ► Performances of fabricated white LED indicated the potential application of phosphors.

  4. Photocatalytic performance of cylindrical reactor inserted with UV light-emitting-diodes for purification of low-level toxic volatile organic compounds

    International Nuclear Information System (INIS)

    Jo, Wan K.; Kang, Hyun J.

    2012-01-01

    Highlights: ► Photocatalyst baked at 350 °C exhibited the highest BTEX degradation efficiency. ► Conventional lamp evidenced a higher degradation efficiency compared to LEDs. ► LEDs was more energy-efficient than conventional lamp for BTEX degradation. ► As the residence time increased, the average degradation efficiency increased. - Abstract: The present study investigated the photocatalytic performance of a cylindrical reactor inserted with UV light-emitting-diodes for the decomposition of low-level (0.1 ppm) gas-phase organic compounds (benzene, toluene, ethyl benzene and xylene (BTEX)). The morphological and optical properties of photocatalysts (Degussa P-25 TiO 2 ) baked at different temperatures were determined using a range of spectral instruments. The photocatalyst baked at 350 °C exhibited the highest conversion efficiencies for both benzene and toluene (81 and ∼100%, respectively). The conventional lamp showed a higher conversion efficiency for benzene compared to the 380-nm UV-LED and a higher conversion efficiency for benzene and toluene than the 365-nm UV-LED. However, the ratios of conversion efficiency to electric power consumption were 2.5–3.0 times higher for the latter light source than the former source. Moreover, as the residence time increased from 0.2 to 1.2 min, the average conversion efficiencies for BTEX of the 3-h photocatalytic process increased from nearly zero to 81%, 7 to nearly 100%, 20 to nearly 100%, and 29–30 to nearly 100%, respectively. The cylindrical photocatalytic reactor inserted with UV-LEDs could be energy-efficiently applied for the decomposition of low-level toxic compounds after optimization of the operating conditions.

  5. Photocatalytic performance of cylindrical reactor inserted with UV light-emitting-diodes for purification of low-level toxic volatile organic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Wan K., E-mail: wkjo@knu.ac.kr [Department of Environmental Engineering, Kyungpook National University, Daegu, 702-701 (Korea, Republic of); Kang, Hyun J., E-mail: khj435@naver.com [Department of Environmental Engineering, Kyungpook National University, Daegu, 702-701 (Korea, Republic of)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer Photocatalyst baked at 350 Degree-Sign C exhibited the highest BTEX degradation efficiency. Black-Right-Pointing-Pointer Conventional lamp evidenced a higher degradation efficiency compared to LEDs. Black-Right-Pointing-Pointer LEDs was more energy-efficient than conventional lamp for BTEX degradation. Black-Right-Pointing-Pointer As the residence time increased, the average degradation efficiency increased. - Abstract: The present study investigated the photocatalytic performance of a cylindrical reactor inserted with UV light-emitting-diodes for the decomposition of low-level (0.1 ppm) gas-phase organic compounds (benzene, toluene, ethyl benzene and xylene (BTEX)). The morphological and optical properties of photocatalysts (Degussa P-25 TiO{sub 2}) baked at different temperatures were determined using a range of spectral instruments. The photocatalyst baked at 350 Degree-Sign C exhibited the highest conversion efficiencies for both benzene and toluene (81 and {approx}100%, respectively). The conventional lamp showed a higher conversion efficiency for benzene compared to the 380-nm UV-LED and a higher conversion efficiency for benzene and toluene than the 365-nm UV-LED. However, the ratios of conversion efficiency to electric power consumption were 2.5-3.0 times higher for the latter light source than the former source. Moreover, as the residence time increased from 0.2 to 1.2 min, the average conversion efficiencies for BTEX of the 3-h photocatalytic process increased from nearly zero to 81%, 7 to nearly 100%, 20 to nearly 100%, and 29-30 to nearly 100%, respectively. The cylindrical photocatalytic reactor inserted with UV-LEDs could be energy-efficiently applied for the decomposition of low-level toxic compounds after optimization of the operating conditions.

  6. Visible light-induced photocatalytic degradation of Reactive Blue-19 over highly efficient polyaniline-TiO2 nanocomposite: a comparative study with solar and UV photocatalysis.

    Science.gov (United States)

    Kalikeri, Shankramma; Kamath, Nidhi; Gadgil, Dhanashri Jayant; Shetty Kodialbail, Vidya

    2018-02-01

    Polyaniline-TiO 2 (PANI-TiO 2 ) nanocomposite was prepared by in situ polymerisation method. X-ray diffractogram (XRD) showed the formation of PANI-TiO 2 nanocomposite with the average crystallite size of 46 nm containing anatase TiO 2 . The PANI-TiO 2 nanocomposite consisted of short-chained fibrous structure of PANI with spherical TiO 2 nanoparticles dispersed at the tips and edge of the fibres. The average hydrodynamic diameter of the nanocomposite was 99.5 nm. The band gap energy was 2.1 eV which showed its ability to absorb light in the visible range. The nanocomposite exhibited better visible light-mediated photocatalytic activity than TiO 2 (Degussa P25) in terms of degradation of Reactive Blue (RB-19) dye. The photocatalysis was favoured under initial acidic pH, and complete degradation of 50 mg/L dye could be achieved at optimum catalyst loading of 1 g/L. The kinetics of degradation followed the Langmuir-Hinshelhood model. PANI-TiO 2 nanocomposite showed almost similar photocatalytic activity under UV and visible light as well as in the solar light which comprises of radiation in both UV and visible light range. Chemical oxygen demand removal of 86% could also be achieved under visible light, confirming that simultaneous mineralization of the dye occurred during photocatalysis. PANI-TiO 2 nanocomposites are promising photocatalysts for the treatment of industrial wastewater containing RB-19 dye.

  7. Capturing age-related changes in functional contrast sensitivity with decreasing light levels in monocular and binocular vision.

    Science.gov (United States)

    Gillespie-Gallery, Hanna; Konstantakopoulou, Evgenia; Harlow, Jonathan A; Barbur, John L

    2013-09-09

    It is challenging to separate the effects of normal aging of the retina and visual pathways independently from optical factors, decreased retinal illuminance, and early stage disease. This study determined limits to describe the effect of light level on normal, age-related changes in monocular and binocular functional contrast sensitivity. We recruited 95 participants aged 20 to 85 years. Contrast thresholds for correct orientation discrimination of the gap in a Landolt C optotype were measured using a 4-alternative, forced-choice (4AFC) procedure at screen luminances from 34 to 0.12 cd/m(2) at the fovea and parafovea (0° and ±4°). Pupil size was measured continuously. The Health of the Retina index (HRindex) was computed to capture the loss of contrast sensitivity with decreasing light level. Participants were excluded if they exhibited performance outside the normal limits of interocular differences or HRindex values, or signs of ocular disease. Parafoveal contrast thresholds showed a steeper decline and higher correlation with age at the parafovea than the fovea. Of participants with clinical signs of ocular disease, 83% had HRindex values outside the normal limits. Binocular summation of contrast signals declined with age, independent of interocular differences. The HRindex worsens more rapidly with age at the parafovea, consistent with histologic findings of rod loss and its link to age-related degenerative disease of the retina. The HRindex and interocular differences could be used to screen for and separate the earliest stages of subclinical disease from changes caused by normal aging.

  8. Pitfalls and artifacts in measuring absorption spectra and kinetics: the effect of stray light in the UV and red regions

    International Nuclear Information System (INIS)

    Czapski, Gideon; Ozeri, Yair; Goldstein, Sara

    2005-01-01

    Effects of stray light on absorption spectrum and kinetics are discussed. The extent of the stray light depends on the light source, monochromator, wavelength set by the instrument and the absorption of the sample at this wavelength. Effects of the stray light on the shape of the spectrum and the extinction coefficients are shown. Methods for determining the existence and extent of stray light are suggested and are especially relevant for studies using pulse radiolysis, flash photolysis, and stopped-flow techniques. The literature examples for artifacts due to stray light are presented for kinetics and absorption spectra

  9. Decreased reactivation of a herpes simplex virus type 1 (HSV-1) latency associated transcript (LAT) mutant using the in vivo mouse UV-B model of induced reactivation

    Science.gov (United States)

    BenMohamed, Lbachir; Osorio, Nelson; Srivastava, Ruchi; Khan, Arif A.; Simpson, Jennifer L.; Wechsler, Steven L.

    2015-01-01

    Blinding ocular herpetic disease in humans is due to herpes simplex virus type 1 (HSV-1) reactivations from latency, rather than to primary acute infection. The cellular and molecular mechanisms that control the HSV-1 latency-reactivation cycle remain to be fully elucidated. The aim of this study was to determine if reactivation of the HSV-1 latency associated transcript (LAT) deletion mutant (dLAT2903) was impaired in this model, as it is in the rabbit model of induced and spontaneous reactivation and in the explant TG induced reactivation model in mice. The eyes of mice latently infected with wild type HSV-1 strain McKrae (LAT(+) virus) or dLAT2903 (LAT(−) virus) were irradiated with UV-B and reactivation was determined. We found that compared to LAT(−) virus, LAT(+) virus reactivated at a higher rate as determined by shedding of virus in tears on days 3 to 7 after UV-B treatment. Thus, the UV-B induced reactivation model of HSV-1 appears to be a useful small animal model for studying the mechanisms involved in how LAT enhances the HSV-1 reactivation phenotype. The utility of the model for investigating the immune evasion mechanisms regulating the HSV-1 latency/reactivation cycle and for testing the protective efficacy of candidate therapeutic vaccines and drugs are discussed. PMID:26002839

  10. UV Deprivation Influences Social UV Preference in Juvenile Sticklebacks

    Directory of Open Access Journals (Sweden)

    Ricarda Modarressie

    2015-05-01

    Full Text Available Social aggregations occur in many different animal taxa and mainly result from non-random assortment. Investigating factors that shape and maintain the composition of social aggregations are among others a main topic for understanding ecological speciation processes. Aggregation decisions are mediated by olfactory and visual cues, which in many animals are extended into the UV part of the electromagnetic spectrum. Here, we were interested in developmental plasticity of social preferences with respect to UV radiation in aquatic organisms. Specifically, we tested whether different lighting environments with respect to UV wavelengths during early life stages influence the shoaling preference in juvenile threespine sticklebacks (Gasterosteus aculeatus. Family (full-sibling groups were split and reared under UV-lacking (UV- and UV-present (UV+ lighting conditions. Subsequent shoal choice experiments, in which test fish from both rearing conditions could simultaneously choose between a shoal seen behind a UV-blocking (UV- and a shoal seen behind a UV-transmitting (UV+ filter, revealed a significant effect of lighting condition during rearing on association preference. Test fish that had been deprived of UV spent significantly more time near the UV- shoal compared to the test fish reared under full-spectrum lighting conditions. The results are discussed with respect to plasticity of the visual system and environmental lighting conditions.

  11. Effects of UV-C Light Exposure and Refrigeration on Phenolic and Antioxidant Profiles of Subtropical Fruits (Litchi, Longan, and Rambutan in Different Fruit Forms

    Directory of Open Access Journals (Sweden)

    Peilong Li

    2017-01-01

    Full Text Available The objectives of this study were to investigate how UV-C irradiation and refrigeration affect shelf-life and antioxidant level of litchi, longan, and rambutan. Three forms (whole, dehulled, and destoned of fresh fruits were treated by refrigeration and UV-C irradiations. After processing, deterioration rate, phenolics compounds, and antioxidant capacity were quantified. The deterioration rate was recorded as decay index. The results showed that both refrigeration and UV-C exposure extended the shelf-life of the fruits. The refrigeration enriched antioxidant levels of litchi but caused nutritional degradation in longan and rambutan; UV-C radiation enriched litchi antioxidant contents but was related to reduction of antioxidant capacity in longan and rambutan. Removing hulls and stones was associated with the decrease of antioxidants in litchi. The effects on antioxidant levels varied from fruit to fruit, resulting from hormesis phenomenon. The change of phytochemical levels was hypothesized as an accumulative process. The effects of fruit forms were not consistent in different fruits, which could be multifactorially influenced.

  12. Coupled UV-exposure and microbial decomposition improves measures of organic matter degradation and light models in humic lake

    DEFF Research Database (Denmark)

    Madsen-Østerbye, Mikkel; Kragh, Theis; Pedersen, Ole

    2018-01-01

    Increasing terrestrial input of colored dissolved organic matter (CDOM) to temperate softwater lakes has reduced transparency, distribution of pristine rosette plants and overall biodiversity in recent decades. We examined microbial and UV-induced reduction of absorption by CDOM and dissolved org...

  13. The response of mammalian cells to UV-light reveals Rad54-dependent and independent pathways of homologous recombination

    DEFF Research Database (Denmark)

    Eppink, Berina; Tafel, Agnieszka A; Hanada, Katsuhiro

    2011-01-01

    with lesions in replicating DNA. The core HR protein in mammalian cells is the strand exchange protein RAD51, which is aided by numerous proteins, including RAD54. We used RAD54 as a cellular marker for HR to study the response of mammalian embryonic stem (ES) cells to UV irradiation. In contrast to yeast, ES...

  14. Bactericidal activity under UV and visible light of cotton fabrics coated with anthraquinone-sensitized TiO2

    KAUST Repository

    Rahal, Raed; Le Bé chec, Mickaë l; Guyoneaud, Ré my; Pigot, Thierry; Paolacci, H.; Lacombe, Sylvie M.

    2013-01-01

    . The experimental method allowed the accurate quantification of bacteria survival on photoactive surfaces and films under UVA and UV-free visible irradiation. Cotton fabrics coated with TiO2, anthraquinone or anthraquinone-sensitized TiO2 display a significant

  15. UV-light promoted C-H bond activation of benzene and fluorobenzenes by an iridium(i) pincer complex.

    Science.gov (United States)

    Hauser, Simone A; Emerson-King, Jack; Habershon, Scott; Chaplin, Adrian B

    2017-03-28

    Iridium(i) carbonyl complex [Ir(2,6-(P t Bu 2 CH 2 ) 2 C 6 H 3 )(CO)] undergoes reversible C-H bond activation of benzene and a series of fluorobenzenes on UV irradiation. Exclusive ortho-selectivity is observed in reactions of fluorobenzene and 1,2-difluorobenzene.

  16. UV-light promoted C–H bond activation of benzene and fluorobenzenes by an iridium(i) pincer complex

    OpenAIRE

    Hauser, Simone A.; Emerson-King, Jack; Habershon, Scott; Chaplin, Adrian B.

    2017-01-01

    Iridium(I) carbonyl complex [Ir(2,6-(PtBu2CH2)2C6H3)(CO)] undergoes reversible C–H bond activation of benzene and a series of fluorobenzenes on UV irradiation. Exclusive ortho-selectivity is observed in reactions of fluorobenzene and 1,2-difluorobenzene.\\ud \\ud

  17. Different efficiency of UmuDC and MucAB proteins in UV light induced mutagenesis in Escherichia coli

    International Nuclear Information System (INIS)

    Blanco, M.; Herrera, G.; Aleixandre, V.

    1986-01-01

    Two multicopy plasmids carrying either the umuDC or the mucAB operon were used to compare the efficiency of UmuDC and MucAB proteins in UV mutagenesis of Escherichia coli K12. It was found that in recA + uvr + bacteria, plasmid pIC80, mucAB + mediated UV mutagenesis more efficiently than did plasmid pSE 117, umuDC + . A similar result was obtained in lex A51(Def) cells, excluding the possibility that this was due to a differential regulation by LexA of the umuDC and mucAB operons. We conclude that some structural characteristic of the UmuDC and MucAB proteins determines their different efficiency in UV mutagenesis. This characteristic could be also responsible for the observation that in the recA430 mutant, pIC80 but no pSE117 can mediate UV mutagenesis. In the recAS142 mutant pIC80 also promoted UV mutagenesis more efficiently than pSE117. In this mutant, the recombination proficiency, the protease activity toward LexA and the mutation frequency were increased by the presence of adenine in the medium. In recA + uvrB5 bacteria, plasmid pSE117, umuDC caused both an increase in UV sensitivity as well as a reduction in the mutation frequency. These negative effects resulting from the overproduction of UmuDC proteins were higher in recA142 uvrB5 than in recA + uvrB5 cells. In contrast, overproduction of MucAB proteins in excision-deficient bacteria containing pIC80 led to a large increase in the mutation frequency. We suggest that the functional differences between UmuDC and MucAB proteins might be due to their different dependence on the direct role of RecA protease in UV mutagenesis. (orig.)

  18. Probing the Effects of Templating on the UV and Visible Light Photocatalytic Activity of Porous Nitrogen-Modified Titania Monoliths for Dye Removal.

    Science.gov (United States)

    Nursam, Natalita M; Wang, Xingdong; Tan, Jeannie Z Y; Caruso, Rachel A

    2016-07-13

    Porous nitrogen-modified titania (N-titania) monoliths with tailored morphologies were prepared using phase separation and agarose gel templating techniques. The doping and templating process were simultaneously carried out in a one-pot step using alcohol amine-assisted sol-gel chemistry. The amount of polymer used in the monoliths that were prepared using phase separation was shown to affect both the physical and optical properties: higher poly(ethylene glycol) content increased the specific surface area, porosity, and visible light absorption of the final materials. For the agarose-templated monoliths, the infiltration conditions affected the monolith morphology. A porous monolith with high surface area and the least shrinkage was obtained when the N containing alkoxide precursor was infiltrated into the agarose scaffolds at 60 °C. The effect of the diverse porous morphologies on the photocatalytic activity of N-titania was studied for the decomposition of methylene blue (MB) under visible and UV light irradiation. The highest visible light activity was achieved by the agarose-templated N-titania monolith, in part due to higher N incorporation. This sample also showed better UV activity, partly because of the higher specific surface area (up to 112 m(2) g(-1)) compared to the phase separation-induced monoliths (up to 103 m(2) g(-1)). Overall, agarose-templated, porous N-titania monoliths provided better features for effectively removing the MB contaminant.

  19. UV and visible light photocatalytic activity of Au/TiO2 nanoforests with Anatase/Rutile phase junctions and controlled Au locations.

    Science.gov (United States)

    Yu, Yang; Wen, Wei; Qian, Xin-Yue; Liu, Jia-Bin; Wu, Jin-Ming

    2017-01-24

    To magnify anatase/rutile phase junction effects through appropriate Au decorations, a facile solution-based approach was developed to synthesize Au/TiO 2 nanoforests with controlled Au locations. The nanoforests cons®isted of anatase nanowires surrounded by radially grown rutile branches, on which Au nanoparticles were deposited with preferred locations controlled by simply altering the order of the fabrication step. The Au-decoration increased the photocatalytic activity under the illumination of either UV or visible light, because of the beneficial effects of either electron trapping or localized surface plasmon resonance (LSPR). Gold nanoparticles located preferably at the interface of anatase/rutile led to a further enhanced photocatalytic activity. The appropriate distributions of Au nanoparticles magnify the beneficial effects arising from the anatase/rutile phase junctions when illuminated by UV light. Under the visible light illumination, the LSPR effect followed by the consecutive electron transfer explains the enhanced photocatalysis. This study provides a facile route to control locations of gold nanoparticles in one-dimensional nanostructured arrays of multiple-phases semiconductors for achieving a further increased photocatalytic activity.

  20. A dual-directional light-control film with a high-sag and high-asymmetrical-shape microlens array fabricated by a UV imprinting process

    International Nuclear Information System (INIS)

    Lin, Ta-Wei; Liao, Yunn-Shiuan; Chen, Chi-Feng; Yang, Jauh-Jung

    2008-01-01

    A dual-directional light-control film with a high-sag and high-asymmetric-shape long gapless hexagonal microlens array fabricated by an ultra-violent (UV) imprinting process is presented. Such a lens array is designed by ray-tracing simulation and fabricated by a micro-replication process including gray-scale lithography, electroplating process and UV curing. The shape of the designed lens array is similar to that of a near half-cylindrical lens array with a periodical ripple. The measurement results of a prototype show that the incident lights using a collimated LED with the FWHM of dispersion angle, 12°, are diversified differently in short and long axes. The numerical and experimental results show that the FWHMs of the view angle for angular brightness in long and short axis directions through the long hexagonal lens are about 34.3° and 18.1° and 31° and 13°, respectively. Compared with the simulation result, the errors in long and short axes are about 5% and 16%, respectively. Obviously, the asymmetric gapless microlens array can realize the aim of the controlled asymmetric angular brightness. Such a light-control film can be used as a power saving screen compared with convention diffusing film for the application of a rear projection display

  1. Reaction analysis of initial oxidation of silicon by UV-light-excited ozone and the application to rapid and uniform SiO2 film growth

    International Nuclear Information System (INIS)

    Tosaka, Aki; Nonaka, Hidehiko; Ichimura, Shingo; Nishiguchi, Tetsuya

    2007-01-01

    UV-light-excited O 3 prepared by irradiation of nearly 100% pure O 3 with a KrF excimer laser (λ=248 nm, irradiated area=30x10 mm 2 ) was utilized for low-temperature Si oxidation. The initial oxidation rate was determined, and the activation energy was shown to be almost zero (0.049 eV). To clarify the optimum oxidation conditions, the dependence of the SiO 2 film growth rate on the total photon number and the photon density was investigated. The evolution of O 3 density after UV-light irradiation was experimentally measured, and the O( 1 D) density change is discussed. O( 1 D) density changes are successfully explained by using a second-order reaction model, indicating that a pulse supply of oxygen atoms is essential in the initial oxidation process. The uniform oxidation of 8 in. Si wafer has been carried out using a wafer-transfer type chamber by irradiating the wafer with KrF excimer laser light expanded linearly to the wafer width by a concave lens

  2. Inactivation of normal and mutant Neurospora crassa conidia by visible light and near-UV: role of 1O2, carotenoid composition and sensitizer location

    International Nuclear Information System (INIS)

    Thomas, S.A.; Sargent, M.L.; Tuveson, R.W.

    1981-01-01

    Inactivation of Neurospora crassa conidia from wild-type and mutant strains by visible and near-ultraviolet light was investigated in the presence and absence of photosensitizing dyes. Inactivation by near-UV was virtually unchanged by the presence of deuterium oxide or azide suggesting that, contrary to the situation with visible light and photosensitizing dyes, 1 O 2 is not involved in any substantial way in the formation of lethal lesions. Carotenoid deficient strains were similar to wild-type strains in sensitivity to near-UV inactivation which is consistent with 1 O 2 not being involved. Photodynamic inactivation of conidia by visible light occurred in the presence of methylene blue (MB), toluidine blue O (TB), or acridine orange (AO). Carotenoid deficient strains were more sensitive to such inactivation only when MB and TB were used. This suggests that MB and TB mediated damage involves the cell membrane where carotenoids are available for quenching, whereas AO mediated damage occurs in the nucleus sequestered from the protective influence of carotenoids. A newly isolated, lemon-yellow mutant exhibited sensitivities to photodynamic inactivation similar to other pure-white mutants. The sensitivity of this pigmented mutant is apparently related to insufficient unsaturation of the two coloured carotenoids produced by the mutant. (author)

  3. Degradation of (InAlGa)N-based UV-B light emitting diodes stressed by current and temperature

    Energy Technology Data Exchange (ETDEWEB)

    Glaab, Johannes, E-mail: johannes.glaab@fbh-berlin.de; Ploch, Christian; Kelz, Rico; Stölmacker, Christoph; Lapeyrade, Mickael; Ploch, Neysha Lobo; Rass, Jens; Kolbe, Tim; Einfeldt, Sven; Weyers, Markus [Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin (Germany); Mehnke, Frank; Kuhn, Christian; Wernicke, Tim [Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, EW 6-1, 10623 Berlin (Germany); Kneissl, Michael [Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin (Germany); Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, EW 6-1, 10623 Berlin (Germany)

    2015-09-07

    The degradation of the electrical and optical properties of (InAlGa)N-based multiple quantum well light emitting diodes (LEDs) emitting near 308 nm under different stress conditions has been studied. LEDs with different emission areas were operated at room temperature and at constant current densities of 75 A/cm{sup 2}, 150 A/cm{sup 2}, and 225 A/cm{sup 2}. In addition, the heat sink temperature was varied between 15 °C and 80 °C. Two main modes for the reduction of the optical power were found, which dominate at different times of operation: (1) Within the first 100 h, a fast drop of the optical power is observed scaling exponentially with the temperature and having an activation energy of about 0.13 eV. The drop in optical power is accompanied by changes of the current-voltage (I-V) characteristic. (2) For operation times beyond 100 h, the optical power decreases slowly which can be reasonably described by a square root time dependence. Here, the degradation rate depends on the current density, rather than the current. Again, the rate of optical power reduction of the second mode depends exponentially on the temperature with an activation energy of about 0.21 eV. The drop in the optical power is accompanied by an increased reverse-bias leakage current.

  4. Degradation of (InAlGa)N-based UV-B light emitting diodes stressed by current and temperature

    International Nuclear Information System (INIS)

    Glaab, Johannes; Ploch, Christian; Kelz, Rico; Stölmacker, Christoph; Lapeyrade, Mickael; Ploch, Neysha Lobo; Rass, Jens; Kolbe, Tim; Einfeldt, Sven; Weyers, Markus; Mehnke, Frank; Kuhn, Christian; Wernicke, Tim; Kneissl, Michael

    2015-01-01

    The degradation of the electrical and optical properties of (InAlGa)N-based multiple quantum well light emitting diodes (LEDs) emitting near 308 nm under different stress conditions has been studied. LEDs with different emission areas were operated at room temperature and at constant current densities of 75 A/cm 2 , 150 A/cm 2 , and 225 A/cm 2 . In addition, the heat sink temperature was varied between 15 °C and 80 °C. Two main modes for the reduction of the optical power were found, which dominate at different times of operation: (1) Within the first 100 h, a fast drop of the optical power is observed scaling exponentially with the temperature and having an activation energy of about 0.13 eV. The drop in optical power is accompanied by changes of the current-voltage (I-V) characteristic. (2) For operation times beyond 100 h, the optical power decreases slowly which can be reasonably described by a square root time dependence. Here, the degradation rate depends on the current density, rather than the current. Again, the rate of optical power reduction of the second mode depends exponentially on the temperature with an activation energy of about 0.21 eV. The drop in the optical power is accompanied by an increased reverse-bias leakage current

  5. Influence of post-deposition treatment by UV light and oxygen (ozone) on 350 nm damage thresholds of SiO2 films deposited from sols

    International Nuclear Information System (INIS)

    Thomas, I.; Wilder, J.; Lee, A.; George, D.

    1988-01-01

    Certain multilayer porous silica AR coatings on fused silica substrates prepared by the sol-gel process have been found to have a much lower laser damage threshold than single layer coatings prepared by the same method. Treatment with UV light in the presence of oxygen (which gives ozone) at low temperature was found to restore damage thresholds to the levels found in single layers. Damage thresholds were measured at 350 nm with a 25 ns pulse for 1000 shots at 25 Hz. The effect of exposure time and other factors such as replacement of oxygen with nitrogen and vacuum are described

  6. UV light induced insulator-metal transition in ultra-thin ZnO/TiO{sub x} stacked layer grown by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Saha, D., E-mail: sahaphys@gmail.com, E-mail: pmisra@rrcat.gov.in; Misra, P., E-mail: sahaphys@gmail.com, E-mail: pmisra@rrcat.gov.in; Joshi, M. P.; Kukreja, L. M. [Laser Materials Processing Division, Raja Ramanna Centre for Advanced Technology, Indore 452 013 (India)

    2016-08-28

    In the present study, atomic layer deposition has been used to grow a series of Ti incorporated ZnO thin films by vertically stacking different numbers (n = 1–7) of ZnO/TiO{sub x} layers on (0001) sapphire substrates. The effects of defect states mediated chemisorption of O{sub 2} and/OH groups on the electrical properties of these films have been investigated by illuminating the samples under UV light inside a high vacuum optical cryostat. The ultra-thin film having one stacked layer (n = 1) did not show any change in its electrical resistance upon UV light exposure. On the contrary, marginal drop in the electrical resistivity was measured for the samples with n ≥ 3. Most surprisingly, the sample with n = 2 (thickness ∼ 12 nm) showed an insulator to metal transition upon UV light exposure. The temperature dependent electrical resistivity measurement on the as grown film (n = 2) showed insulating behaviour, i.e., diverging resistivity on extrapolation to T→ 0 K. However, upon UV light exposure, it transformed to a metallic state, i.e., finite resistivity at T → 0 K. Such an insulator-metal transition plausibly arises due to the de-trapping of conduction electrons from the surface defect sites which resulted in an upward shift of the Fermi level above the mobility edge. The low-temperature electron transport properties on the insulating film (n = 2) were investigated by a combined study of zero field electrical resistivity ρ(T) and magnetoresistance (MR) measurements. The observed negative MR was found to be in good agreement with the magnetic field induced suppression of quantum interference between forward-going paths of tunnelling electrons. Both ρ(T) and MR measurements provided strong evidence for the Efros-Shklovskii type variable range hopping conduction in the low-temperature (≤40 K) regime. Such studies on electron transport in ultra-thin n-type doped ZnO films are crucial to achieve optimum functionality

  7. Photocatalytic performance of Sn-doped TiO2 nanostructured mono and double layer thin films for Malachite Green dye degradation under UV and vis-lights

    International Nuclear Information System (INIS)

    Sayilkan, F.; Asiltuerk, M.; Tatar, P.; Kiraz, N.; Arpac, E.; Sayilkan, H.

    2007-01-01

    Nanostructure Sn 4+ -doped TiO 2 based mono and double layer thin films, contain 50% solid ratio of TiO 2 in coating have been prepared on glass surfaces by spin-coating technique. Their photocatalytic performances were tested for degradation of Malachite Green dye in solution under UV and vis irradiation. Sn 4+ -doped nano-TiO 2 particle a doping ratio of about 5[Sn 4+ /Ti(OBu n ) 4 ; mol/mol%] has been synthesized by hydrotermal process at 225 deg. C. The structure, surface and optical properties of the thin films and/or the particles have been investigated by XRD, BET and UV/vis/NIR techniques. The results showed that the double layer coated glass surfaces have a very high photocatalytic performance than the other one under UV and vis lights. The results also proved that the hydrothermally synthesized nano-TiO 2 particles are fully anatase crystalline form and are easily dispersed in water. The results also reveal that the coated surfaces have hydrophilic property

  8. 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)

  9. Comparison of Avian Responses to UV-Light-Reflective Paint on Wind Turbines: Subcontract Report, July 1999--December 2000

    Energy Technology Data Exchange (ETDEWEB)

    Young, D. P., Jr.; Erickson, W. P.; Strickland, M. D.; Good, R. E.; Sernka, K. J.

    2003-01-01

    To reduce the numbers of avian collisions with wind turbines, several measures have been employed with various levels of success. One hypothesis is that painting turbine blades to increase their visibility may reduce avian fatalities. This study examined the effects of painting wind turbine blades with UV-reflective paint on bird use and mortality at the Foote Creek Rim Wind Plant in Carbon County, Wyoming.

  10. RecA-independent resistance to irradiation with u.v. light in acid-habituated Escherichia coli

    International Nuclear Information System (INIS)

    Goodson, M.; Rowbury, R.J.

    1991-01-01

    Growth of Escherichia coli 1829 ColV, I-K94 at pH 5.0 led to an increase in u.v. resistance compared with cells grown at pH 7.0. This was due to a phenotypic change, since organisms grown at pH 7.0 showed increased resistance after only 2.5-5.0 min incubation at the mildly acid pH. Other E. coli K12 derivatives became more u.v.-resistant at pH 5.0 including uvrA, recA and polAl mutants. Organisms grown at pH 5.0 also showed increased Weigle reactivation of u.v. irradiated λ phage and this applied to the repair-deficient mutants as well as the parent strains. Both the increased u.v. resistance of acid-habituated cells and their increased ability to bring about Weigle reactivation appear to involve RecA-independent processes and are presumably, therefore, independent of the SOS response. (author)

  11. A photo-tunable membrane based on inter-particle crosslinking for decreasing diffusion rates

    KAUST Repository

    Li, Song; Moosa, Basem; Chen, Ye; Li, Wengang; Khashab, Niveen M.

    2015-01-01

    %. To prove the applicability of the designed system, the composite membrane was coated on a model drug reservoir tablet. Upon irradiating the tablet with UV light, the original permeability decreased by 57%, and consequently the diffusion rate of the cargo

  12. Reductive and oxidative degradation of iopamidol, iodinated X-ray contrast media, by Fe(III)-oxalate under UV and visible light treatment.

    Science.gov (United States)

    Zhao, Cen; Arroyo-Mora, Luis E; DeCaprio, Anthony P; Sharma, Virender K; Dionysiou, Dionysios D; O'Shea, Kevin E

    2014-12-15

    Iopamidol, widely employed as iodinated X-ray contrast media (ICM), is readily degraded in a Fe(III)-oxalate photochemical system under UV (350 nm) and visible light (450 nm) irradiation. The degradation is nicely modeled by pseudo first order kinetics. The rates of hydroxyl radical (OH) production for Fe(III)-oxalate/H2O2/UV (350 nm) and Fe(III)-oxalate/H2O2/visible (450 nm) systems were 1.19 ± 0.12 and 0.30 ± 0.01 μM/min, respectively. The steady-state concentration of hydroxyl radical (OH) for the Fe(III)-oxalate/H2O2/UV (350 nm) conditions was 10.88 ± 1.13 × 10(-14) M and 2.7 ± 0.1 × 10(-14) M for the Fe(III)-oxalate/H2O2/visible (450 nm). The rate of superoxide anion radical (O2(-)) production under Fe(III)-oxalate/H2O2/UV (350 nm) was 0.19 ± 0.02 μM/min with a steady-state concentration of 5.43 ± 0.473 × 10(-10) M. Detailed product studies using liquid chromatography coupled to Q-TOF/MS demonstrate both reduction (multiple dehalogenations) and oxidation (aromatic ring and side chains) contribute to the degradation pathways. The reduction processes appear to be initiated by the carbon dioxide anion radical (CO2(-)) while oxidation processes are consistent with OH initiated reaction pathways. Unlike most advanced oxidation processes the Fe(III)-oxalate/H2O2/photochemical system can initiate to both reductive and oxidative degradation processes. The observed reductive dehalogenation is an attractive remediation strategy for halogenated organic compounds as the process can dramatically reduce the formation of the problematic disinfection by-products often associated with oxidative treatment processes. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Exploring the critical dependence of adsorption of various dyes on the degradation rate using Ln3+-TiO2 surface under UV/solar light

    International Nuclear Information System (INIS)

    Devi, L. Gomathi; Kumar, S. Girish

    2012-01-01

    Graphical abstract: The surface reactive acidic sites enhances on doping with rare earth ions which facilitates efficient adsorption of the dye molecules on the catalyst surface. In addition, the nature of the dopant, its concentration and electronic configuration additionally contributes to the overall efficiency. Highlights: ► The degradation of structurally different anionic dyes under different pH conditions is reported. ► Pre adsorption of pollutant on catalyst surface is vital for efficient photocatalysis. ► Adsorption of dye on the catalyst surface depends on the substituent's attached to it. ► The dopant with half filled electronic configuration served as shallow traps for charge carriers. - Abstract: The degradation of structurally different anionic dyes like Alizarin Red S (ARS) Amaranth (AR), Brilliant Yellow (BY), Congo Red (CR), Fast Red (FR), Methyl Orange (MO), and Methyl Red (MR) were carried out using Ln 3+ (Ln 3+ = La 3+ , Ce 3+ and Gd 3+ ) doped TiO 2 at different pH conditions under UV/solar light. All the anionic dyes underwent rapid degradation at acidic pH, while resisted at alkaline conditions due to the adsorptive tendency of these dyes on the catalyst surface at different pH conditions. Gd 3+ (0.15 mol%)-TiO 2 exhibited better activity compared to other photocatalyst ascribed to half filled electronic configuration of Gd 3+ ions. It is proposed that Ln 3+ serves only as charge carrier traps under UV light, while it also act as visible light sensitizers under solar light. Irrespective of the catalyst and excitation source, the dye degradation followed the order: AR > FR > MO > MR > ARS > BY > CR. The results suggest that pre-adsorption of the pollutant is vital for efficient photocatalysis which is dependent on the nature of the substituent's group attached to the dye molecule.

  14. Ease synthesis of mesoporous WO3-TiO2 nanocomposites with enhanced photocatalytic performance for photodegradation of herbicide imazapyr under visible light and UV illumination.

    Science.gov (United States)

    Ismail, Adel A; Abdelfattah, Ibrahim; Helal, Ahmed; Al-Sayari, S A; Robben, L; Bahnemann, D W

    2016-04-15

    Herein, we report the ease synthesis of mesoporous WO3-TiO2 nanocomposites at different WO3 contents (0-5wt%) together with their photocatalytic performance for the degradation of the imazapyr herbicide under visible light and UV illumination. XRD and Raman spectra indicated that the highly crystalline anatase TiO2 phase and monoclinic and triclinic of WO3 were formed. The mesoporous TiO2 exhibits large pore volumes of 0.267cm(3)g-1 and high surface areas of 180m(2)g(-1) but they become reduced to 0.221cm(3)g(-1) and 113m(2)g(-1), respectively upon WO3 incorporation, with tunable mesopore diameter in the range of 5-6.5nm. TEM images show WO3-TiO2 nanocomposites are quite uniform with 10-15nm of TiO2 and 5-10nm of WO3 sizes. Under UV illumination, the overall photocatalytic efficiency of the 3% WO3-TiO2 nanocomposite is 3.5 and 6.6 times higher than that of mesoporous TiO2 and commercial UV-100 photocatalyst, respectively. The 3% WO3-TiO2 nanocomposite is considered to be the optimum photocatalyst which is able to degrade completely (100% conversion) of imazapyr herbicide along 120min with high photonic efficiency ∼8%. While under visible light illumination, the 0.5% WO3-TiO2 nanocomposite is the optimum photocatalyst which achieves 46% photocatalytic efficiency. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Confluent holding leads to a transient enhancement in mutagenesis in UV-light-irradiated xeroderma pigmentosum, Gardner's syndrome and normal human diploid fibroblasts

    International Nuclear Information System (INIS)

    Grosovsky, A.J.; Little, J.B.

    1985-01-01

    The influence of confluent holding periods of 0-24 h of UV-light-induced mutagenesis has been investigated in several human cell strains including xeroderma pigmentosum complementation group A (XPA), Gardner's syndrome (GS) and normal human diploid fibroblasts (NHDF). Confluent cultures of NHDF exposed to UV light exhibited a time-dependent increase in survival when subculture was delayed up to 24 h after irradiation. GS and XPA fibroblasts showed no such increase. When allowed confluent holding periods of 1.5-24 h, GS, XPA and NHDF all exhibited a transient enhancement of mutagenesis such that a 5-10-fold increase in mutation frequency was observed in cells subcultured at 6-9 h after irradiation as compared to cells subcultured at 3-6 h. A decline in mutation frequency prior to the mutagenesis peak was observed in GS and normal cells but not in XPA. After 24 h of confluent holding, the mutation frequency in irradiated GS and NHDF had returned to near background levels although XPA mutation frequencies remain similar to those observed in immediately subcultured cells. A model to explain these overall results is discussed. (Auth.)

  16. UV-light-assisted ethanol sensing characteristics of g-C3N4/ZnO composites at room temperature

    Science.gov (United States)

    Zhai, Jiali; Wang, Tao; Wang, Chuang; Liu, Dechen

    2018-05-01

    A highly efficient UV-light-assisted room temperature sensor based on g-C3N4/ZnO composites were prepared by an in situ precipitation method. The thermostability, composition, structure, and morphology properties of the as-prepared g-C3N4/ZnO composites were characterized by TGA, XRD, FT-IR, TEM, and XPS, respectively. And then, we studied the ethanol (C2H5OH) sensing performance of the g-C3N4/ZnO composites at the room temperature. Compared with pure ZnO and g-C3N4, the gas sensing activity of g-C3N4/ZnO composites was greatly improved at room temperature, for example, the g-C3N4/ZnO-8% composites showed an obvious response of 121-40 ppm C2H5OH at room temperature, which was 60 times higher than the pure ZnO based on the sensors under the same condition. The great enhancement of the C2H5OH sensing properties of composites can be understood by the efficient separation of photogenerated charge carriers of g-C3N4/ZnO heterogeneous and the UV-light catalytic effect. Finally, a possible mechanism for the gas sensing activity was proposed.

  17. No indications of an enhanced UV-light-induced unscheduled DNA synthesis in splenocytes of mice following a low-dose irradiation in vivo or in vitro

    International Nuclear Information System (INIS)

    Wojcik, A.; Seemayer, C.A.; Mueller, W.U.; Streffer, C.

    1995-01-01

    One of the open questions regarding the adaptive response to ionizing radiation is whether it can be induced in G 0 lymphocytes. In the majority of experiments in which an adaptive response in G 0 lymphocytes was observed, the adapting dose was applied in vivo. In order to investigate whether there is some in vivo component of adaptive response, mouse splenocytes of the C57BL/6 strain were irradiated with 0.1 Gy x-rays either in vivo or in vitro, and their UV-light-induced unscheduled DNA synthesis (UDS) levels were determined autoradiographically. An augmented UV-light-induced UDS following an adapting dose applied in vivo has previously been described by several authors in splenocytes of C57BL/6 mice, indicating that the adapting dose enhanced the DNA repair capacity of lymphocytes. In the present investigation, however, no evidence of an adaptive response could be seen regardless of whether the adapting dose was given in vivo or in vitro. Those results present a further indication for the fact that the adaptive response to ionizing radiation is not always inducible, even in lymphocytes of an inbred mouse strain in which its existence has been reported before. (orig.)

  18. First light for avian embryos: eggshell thickness and pigmentation mediate variation in development and UV exposure in wild bird eggs

    Czech Academy of Sciences Publication Activity Database

    Maurer, G.; Portugal, S. J.; Hauber, M. E.; Mikšík, Ivan; Russell, D. G. D.; Cassey, P.

    2015-01-01

    Roč. 29, č. 2 (2015), s. 209-218 ISSN 0269-8463 R&D Projects: GA ČR(CZ) GA15-01948S Institutional support: RVO:67985823 Keywords : breeding birds * eggs hell colour * light transmission * nesting behaviour * pigments * ultraviolet light Subject RIV: ED - Physiology Impact factor: 5.210, year: 2015

  19. Green tide deactivation with layered-structure cuboids of Ag/CaTiO3 under UV light

    International Nuclear Information System (INIS)

    Lee, Soo-Wohn; Lozano-Sánchez, L.M.; Rodríguez-González, V.

    2013-01-01

    Graphical abstract: Synergic reasons such as mass transfer, morphology, biocide properties, UV-A photoresponse, and electron trapping that reduce recombination on Ag/CaTiO 3 nanocomposites, have the potential for the generation of reactive radicals that promote the fatal irreversible deactivation of Tetraselmis suecica algae in 12 min under UV-A irradiation. -- Highlights: • An alternative to deactivate harmful green tide is proposed by employing Ag/CaTiO 3 . • Particles of perovskite-like have rectangular prisms morphology with AgNPs ∼13 nm. • The cuboids achieve complete inactivation of Tetraselmis suecica algae in 12 min. • AgNPs functionalization induce fatal irreversible damages on the algae surface. -- Abstract: In this work, an alternative to deactivate noxious green tide Tetraselmis suecica in the short-term is proposed by employing Perovskite-like cube-shaped, crystalline CaTiO 3 semiconductors functionalized with atomic silver nanoparticles. CaTiO 3 was prepared by a microwave-assisted hydrothermal method and then Ag 0 NPs (1 wt% of CaTiO 3 ), were added by the photoreduction method. The XRD results show that crystalline CaTiO 3 has an orthorhombic unit cell with a Perovskite-like structure. Images obtained by FESEM and HRTEM microscopies show well-faceted CaTiO 3 rectangular prismatic morphology functionalizated with silver nanoparticles ∼13.5 nm. XPS and EDS-FESEM has confirmed the composition of CaTiO 3 and silver occurring mainly as reduced metal. The UV inactivation of noxious T. suecica with Ag/CaTiO 3 nanocomposites formed on bare materials results in complete deactivation of the algae in 12 min. The direct contact between harmful algae and Ag/CaTiO 3 nanocomposite is necessary to deactivate the algae and inhibits algae viability

  20. ZnCr2S4: Highly effective photocatalyst converting nitrate into N2 without over-reduction under both UV and pure visible light

    Science.gov (United States)

    Yue, Mufei; Wang, Rong; Cheng, Nana; Cong, Rihong; Gao, Wenliang; Yang, Tao

    2016-08-01

    We propose several superiorities of applying some particular metal sulfides to the photocatalytic nitrate reduction in aqueous solution, including the high density of photogenerated excitons, high N2 selectivity (without over-reduction to ammonia). Indeed, ZnCr2S4 behaved as a highly efficient photocatalyst, and with the assistance of 1 wt% cocatalysts (RuOx, Ag, Au, Pd, or Pt), the efficiency was greatly improved. The simultaneous loading of Pt and Pd led to a synergistic effect. It offered the highest nitrate conversion rate of ~45 mg N/h together with the N2 selectivity of ~89%. Such a high activity remained steady after 5 cycles. The optimal apparent quantum yield at 380 nm was 15.46%. More importantly, with the assistance of the surface plasma resonance effect of Au, the visible light activity achieved 1.352 mg N/h under full arc Xe-lamp, and 0.452 mg N/h under pure visible light (λ > 400 nm). Comparing to the previous achievements in photocatalytic nitrate removal, our work on ZnCr2S4 eliminates the over-reduction problem, and possesses an extremely high and steady activity under UV-light, as well as a decent conversion rate under pure visible light.

  1. Standard guide for use of UV-A and visible light sources and meters used in the liquid penetrant and magnetic particle methods

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2004-01-01

    1.1 This guide describes the use of UV-A/Visible light sources and meters used for the examination of materials by the liquid penetrant and magnetic particle processes. This guide may be used to help support the needs for appropriate light intensities and light measurement. 1.2 This guide also provides a reference: 1.2.1 To assist in the selection of light sources and meters that meet the applicable specifications or standards. 1.2.2 For use in the preparation of internal documentation dealing with liquid penetrant or magnetic particle examination of materials and parts. 1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to inch-pound units that are provided for information only and are not considered standard 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and det...

  2. ZnCr2S4: Highly effective photocatalyst converting nitrate into N2 without over-reduction under both UV and pure visible light.

    Science.gov (United States)

    Yue, Mufei; Wang, Rong; Cheng, Nana; Cong, Rihong; Gao, Wenliang; Yang, Tao

    2016-08-03

    We propose several superiorities of applying some particular metal sulfides to the photocatalytic nitrate reduction in aqueous solution, including the high density of photogenerated excitons, high N2 selectivity (without over-reduction to ammonia). Indeed, ZnCr2S4 behaved as a highly efficient photocatalyst, and with the assistance of 1 wt% cocatalysts (RuOx, Ag, Au, Pd, or Pt), the efficiency was greatly improved. The simultaneous loading of Pt and Pd led to a synergistic effect. It offered the highest nitrate conversion rate of ~45 mg N/h together with the N2 selectivity of ~89%. Such a high activity remained steady after 5 cycles. The optimal apparent quantum yield at 380 nm was 15.46%. More importantly, with the assistance of the surface plasma resonance effect of Au, the visible light activity achieved 1.352 mg N/h under full arc Xe-lamp, and 0.452 mg N/h under pure visible light (λ > 400 nm). Comparing to the previous achievements in photocatalytic nitrate removal, our work on ZnCr2S4 eliminates the over-reduction problem, and possesses an extremely high and steady activity under UV-light, as well as a decent conversion rate under pure visible light.

  3. Stability of UV exposed RR-P3BT films by spectroscopic ellipsometry

    International Nuclear Information System (INIS)

    Diware, Mangesh S.; Byun, J. S.; Hwang, S. Y.; Kim, T. J.; Kim, Y. D.

    2013-01-01

    Stability of regioregular poly(3-butylthiophene) (RR-P3BT) films under irradiation of ultra-violet (UV) light has been studied by spectroscopic ellipsometry at room temperature. Consistent decrease in dielectric function with UV exposure time showed the degree of degradation of polymer. This work suggests that, protective methods are mandatory to use this kind of material in optical devices.

  4. White organic light-emitting diodes utilized by near UV-deep blue emitter and exciplex emission.

    Science.gov (United States)

    Park, Young Wook; Kim, Young Min; Choi, Jin Hwan; Park, Tae Hyun; Choi, Hyun Ju; Yu, Hong Jung; Cho, Min Ju; Choi, Dong Hoon; Kim, Sung Hyun; Ju, Byeong Kwon

    2011-02-01

    Numerous investigations have been made into the development of wide color gamut displays for deep-blue OLEDs, including the RGB sub pixels, and white OLEDs (WOLEDs). One of the well known deep-blue emissive dopants, tris(phenyl-methyl-benzimidazolyl)iridium(III) [Ir(pmb)3], successfully introduced its fascinating color coordinate of Commission Internationale de l'Eclairage (CIE) 1931 (0.17, 0.06), however there have been no reports utilizing its accomplishments as WOLEDs. In this report, using only one phosphorescent dopant, the near UV-deep blue emissive Ir(pmb)3, the WOLEDs having the CIE 1931 coordinate of (0.33, 0.38) at 100 cd/m2 with a color rendering index of 85 are demonstrated. The white emission of the fabricated OLEDs are oriented from the near UV-deep blue emission of Ir(pmb)3 and the successfully controlled exciplex emission, between the Ir(pmb)3-host, and the Ir(pmb)3-interfaced material.

  5. Material and device studies for the development of ultra-violet light emitting diodes (UV-LEDS) along polar, non-polar and semi-polar directions

    Science.gov (United States)

    Chandrasekaran, Ramya

    Over the past few years, significant effort was dedicated to the development of ultraviolet light emitting diodes (UV-LEDs) for a variety of applications. Such applications include chemical and biological detection, water purification and solid-state lighting. III-Nitride LEDs based on multiple quantum wells (MQWs) grown along the conventional [0001] (polar) direction suffer from the quantum confined Stark effect (QCSE), due to the existence of strong electric fields that arise from spontaneous and piezoelectric polarization. Thus, there is strong motivation to develop MQW-based III-nitride LED structures grown along non-polar and semi-polar directions. The goal of this dissertation is to develop UV-LEDs along the [0001] polar and [11 2¯ 0] non-polar directions by the method of Molecular Beam Epitaxy (MBE). The polar and non-polar LEDs were grown on the C-plane and R-plane sapphire substrates respectively. This work is a combination of materials science studies related to the nucleation, growth and n- and p-type doping of III-nitride films on these two substrates, as well as device studies related to fabrication and characterization of UV-LEDs. It was observed that the crystallographic orientation of the III-nitride films grown on R-plane sapphire depends strongly on the kinetic conditions of growth of the Aluminum Nitride (AIN) buffer. Specifically, growth of the AIN buffer under group III-rich conditions leads to nitride films having the (11 2¯ 0) non polar planes parallel to the sapphire surface, while growth of the buffer under nitrogen rich conditions leads to nitride films with the (11 2¯ 6) semi-polar planes parallel to the sapphire surface. The electron concentration and mobility for the films grown along the polar, non-polar and semi-polar directions were investigated. P-type doping of Gallium Nitride (GaN) films grown on the nonpolar (11 2¯ 0) plane do not suffer from polarity inversion and thus the material was doped p-type with a hole concentration

  6. 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.

  7. Monolayer alignment on azobenzene surfaces during UV light irradiation: Analysis of optical polarized absorption measurement results and theoretical treatment

    International Nuclear Information System (INIS)

    Zakharov, A.V.; Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa

    2006-01-01

    The influence of the charge separation during the trans-cis conformational change on the surface of azobenzene 6Az10PVA monolayer on the polar liquid-crystal monolayer film, such as 4-n-pentyl-4 ' -cyanobiphenyl(5CB), is investigated. The effective anchoring energy (in the Rapini-Papolar form) is phenomenologically described in the framework of the molecular model, which takes into account the interaction between the surface polarization and surface electric field, for number of conformational states of the boundary surface. It is shown, using the experimental data for the voltage across the 6Az10PVA+5CB film, provided by the surface-potential technique, that the charge separation during the conformational changing, caused by the UV irradiation, may lead to changing of the surface alignment of liquid-crystalline molecules. The influence of the photoisomerization process on the orientational order parameter S 2 (t) using the optical polarized absorption measurement is also investigated

  8. Photodegradation of the UV filter ethylhexyl methoxycinnamate under ultraviolet light: Identification and in silico assessment of photo-transformation products in the context of grey water reuse.

    Science.gov (United States)

    Jentzsch, F; Olsson, O; Westphal, J; Reich, M; Leder, C; Kümmerer, K

    2016-12-01

    To prevent water shortages in the future and to reduce domestic water consumption, decentralized grey water (GW) reuse has become increasingly important. This water has, however, to be free of pollutants. Conventional treatment of GW does not fully eliminate micropollutants such as the UV filter substance ethylhexyl methoxycinnamate (EHMC). EHMC, which is commonly used in sunscreens and personal care products, is an endocrine disruptor and shows potential to bioaccumulation, which is also reflected in its low water solubility. Photolysis has been proposed as an alternative treatment method for other micropollutants, but it is not clear yet whether it can also be used to eliminate EHMC. One goal of this study was to better understand the basic pathways involved in this process. It aimed to identify photo-transformation products (photo-TPs) by using, in the test conditions, an initial concentration of EHMC higher than those expected in the environment. Acetonitrile (ACN) was added in low concentrations to the aqueous solution to overcome the low aquatic solubility of EHMC. The influence of this co-solvent on the degradation kinetics was studied. The photolysis experiments were carried out using a medium pressure mercury lamp, which emits UV light in the range of 200-400nm. The quantum yield of the photolysis of EHMC was 0.0042 and 0.0023mol·Einstein -1 (for 0.2 and 0.5% ACN (v/v), respectively), and the relative and absolute UV photon fluxes were determined. HPLC was used to monitor the elimination kinetics of EHMC, which followed first-order kinetics. The results of LC-MS n analyses revealed that beside others, several oxidized and hydroxylized EHMC isomers were formed as photo-TPs in aqueous solution. Using a set of in silico quantitative structure-activity relationship (QSAR) models, this study also offered new insights concerning the environmental fate and toxicity of the TPs of EHMC. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Sleep deprivation decreases phase-shift responses of circadian rhythms to light in the mouse: role of serotonergic and metabolic signals.

    Science.gov (United States)

    Challet, E; Turek, F W; Laute, M; Van Reeth, O

    2001-08-03

    The circadian pacemaker in the suprachiasmatic nuclei is primarily synchronized to the daily light-dark cycle. The phase-shifting and synchronizing effects of light can be modulated by non-photic factors, such as behavioral, metabolic or serotonergic cues. The present experiments examine the effects of sleep deprivation on the response of the circadian pacemaker to light and test the possible involvement of serotonergic and/or metabolic cues in mediating the effects of sleep deprivation. Photic phase-shifting of the locomotor activity rhythm was analyzed in mice transferred from a light-dark cycle to constant darkness, and sleep-deprived for 8 h from Zeitgeber Time 6 to Zeitgeber Time 14. Phase-delays in response to a 10-min light pulse at Zeitgeber Time 14 were reduced by 30% in sleep-deprived mice compared to control mice, while sleep deprivation without light exposure induced no significant phase-shifts. Stimulation of serotonin neurotransmission by fluoxetine (10 mg/kg), a serotonin reuptake inhibitor that decreases light-induced phase-delays in non-deprived mice, did not further reduce light-induced phase-delays in sleep-deprived mice. Impairment of serotonin neurotransmission with p-chloroamphetamine (three injections of 10 mg/kg), which did not increase light-induced phase-delays in non-deprived mice significantly, partially normalized light-induced phase-delays in sleep-deprived mice. Injections of glucose increased light-induced phase-delays in control and sleep-deprived mice. Chemical damage of the ventromedial hypothalamus by gold-thioglucose (600 mg/kg) prevented the reduction of light-induced phase-delays in sleep-deprived mice, without altering phase-delays in control mice. Taken together, the present results indicate that sleep deprivation can reduce the light-induced phase-shifts of the mouse suprachiasmatic pacemaker, due to serotonergic and metabolic changes associated with the loss of sleep.

  10. Enhanced hydrogen production from water via a photo-catalyzed reaction using chalcogenide d-element nanoparticles induced by UV light.

    Science.gov (United States)

    El Naggar, Ahmed M A; Nassar, Ibrahim M; Gobara, Heba M

    2013-10-21

    Hydrogen has the potential to meet the requirements as a clean non-fossil fuel in the future. The photocatalytic production of H2 through water splitting has been demonstrated and enormous efforts have been published. The present work is an attempt to enhance the production of H2 during water splitting using synthesized nanoparticles based on chalcogenide d-element semiconductors via a photochemical reaction under UV-light in the presence of methanol as a hole-scavenger. In general, the enhanced activity of a semiconductor is most likely due to the effective charge separation of photo generated electrons and holes in the semiconductors. Hence, the utilization of different semiconductors in combination can consequently provide better hydrogen production. Accordingly in this research work, two different semiconductors, with different concentrations, either used individually or combined together were introduced. They in turn produced a high concentration of H2 as detected and measured using gas chromatography. Herein, data revealed that the nano-structured semiconductors prepared through this work are a promising candidate in the production of an enhanced H2 flux under visible UV radiation.

  11. Enhanced photocatalytic performance of sandwiched ZnO@Ag@Cu2O nanorod films: the distinct role of Ag NPs in the visible light and UV region

    International Nuclear Information System (INIS)

    Ren, Shoutian; Wang, Yingying; Wang, Benyang; Wang, Qiang; Zhao, Guoliang

    2015-01-01

    Sandwiched ZnO@Ag@Cu 2 O nanorod films were synthesized by successive electrodeposition, magnetron sputtering and the second electrodeposition. The as-synthesized composites were characterized by x-ray diffraction patterns, field emission scanning electron microscopy, low- and high-resolution transmission electron microscopy and a UV–vis spectrophotometer. Their photocatalytic performance was estimated by the degradation of a methyl orange solution under UV or visible-light irradiation, respectively. In the visible region, due to localized surface plasmon resonance absorption of Ag NPs, ZnO@Ag@Cu 2 O showed a significantly enhanced photocatalytic performance. The enhancement factor of Ag NPs on the catalytic performance of ZnO@Ag@Cu 2 O was estimated as a function of the Cu 2 O deposition time, and the corresponding enhancement mechanism was also evaluated by the monochromatic photocatalytic experiment and discrete dipole approximation simulation. In the UV region, due to the formation of a Schottky junction (e.g. Ag/ZnO, Ag/Cu 2 O), a limited enhanced photocatalytic performance was also realized for ZnO@Ag@Cu 2 O photocatalysts. (paper)

  12. Preparation of perovskite type titanium-bearing blast furnace slag photocatalyst doped with sulphate and investigation on reduction Cr(VI) using UV-vis light

    International Nuclear Information System (INIS)

    Lei, X.F.; Xue, X.X.

    2008-01-01

    Perovskite type titanium-bearing blast furnace slag (TBBFS) and sulphate-modified titanium-bearing blast furnace slag (SO 4 2- /TBBFS) photocatalysts were prepared by the high-energy ball milling method at different calcination temperature. The photocatalysts were characterized by XRD, FTIR, UV-vis diffuse reflectance spectra and SEM measurements. The photocatalytic activities of the different catalysts were evaluated by the photocatalytic reduction of Cr(VI) under UV-vis light irradiation. For the photocatalytic reduction of Cr(VI), the photocatalytic activities of TBBFS catalysts were found to be strongly dependent of the calcination temperature and TBBFS calcined at 700 deg. C showed a higher photocatalytic activity compared to other TBBFS catalysts. In contrast, sulphation of TBBFS improved the photocatalytic activities of SO 4 2- /TBBFS catalysts. At low calcination temperature, the photocatalytic activities of SO 4 2- /TBBFS catalysts were markedly higher than TBBFS prepared under high calcination temperature, suggesting that the presence of surface SO 4 2- favored the photocatalytic reduction of Cr(VI)

  13. Photocatalytic performance of Sn-doped TiO2 nanostructured thin films for photocatalytic degradation of malachite green dye under UV and VIS-lights

    International Nuclear Information System (INIS)

    Sayilkan, F.; Asiltuerk, M.; Tatar, P.; Kiraz, N.; Sener, S.; Arpac, E.; Sayilkan, H.

    2008-01-01

    Sn-doped and undoped nano-TiO 2 particles have been synthesized by hydrotermal process without acid catalyst at 225 deg. C in 1 h. Nanostructure-TiO 2 based thin films, contain at different solid ratio of TiO 2 in coating, have been prepared on glass surfaces by spin-coating technique. The structure, surface morphology and optical properties of the thin films and the particles have been investigated by element analysis and XRD, BET and UV/VIS/NIR techniques. The photocatalytic performance of the films was tested for degradation of malachite green dye in solution under UV and VIS-lights. The results showed that the hydrothermally synthesized nano-TiO 2 particles are fully anatase crystalline form and are easily dispersed in water, the coated surfaces have nearly super-hydrophilic properties and, the doping of transition metal ion efficiently improved the photocatalytic performance of the TiO 2 thin film. The results also proved that malachite green is decomposed catalytically due to the pseudo first-order reaction kinetics

  14. Development of Adaptive Feedback Control System of Both Spatial and Temporal Beam Shaping for UV-Laser Light Source for RF Gun

    CERN Document Server

    Tomizawa, H; Dewa, H; Hanaki, H; Kobayashi, T; Mizuno, A; Suzuki, S; Taniuchi, T; Yanagida, K

    2004-01-01

    The ideal spatial and temporal profiles of a shot-by-shot single laser pulse are essential to suppress the emittance growth of the electron beam from a photo-cathode rf gun. We have been developing highly qualified UV-laser pulse as a light source of the rf gun for an injector candidate of future light sources. The gun cavity is a single-cell pillbox, and the copper inner wall is used as a photo cathode. The electron beam was accelerated up to 4.1 MeV at the maximum electric field on the cathode surface of 175 MV/m. For emittance compensation, two solenoid coils were used. As the first test run, with a microlens array as a simple spatial shaper, we obtained a minimum emittance value of 2 π·mm·mrad with a beam energy of 3.1 MeV, holding its charge to 0.1 nC/bunch. In the next test run, we prepared a deformable mirror for spatial shaping, and a spatial light modulator based on fused-silica plates for temporal shaping. We applied the both adaptive optics to automatically shape the bot...

  15. Action of cis-dichlorobis (cyclopentylamine) platinum (2) (cis-PAD) on L5178Y cells of two strains inversely cross-sensitive to X-rays and UV-light. Part 3. Differential effects of caffeine

    International Nuclear Information System (INIS)

    Szumiel, I.

    1977-01-01

    Two strains of L5178Y murine lymphoma, inversely cross-sensitive to X-rays and UV-light, were shown previously to respond to treatment with an antitumour platinum complex, cis-PAD, in a similar manner as to UV. The difference in sensitivity to cis-PAD, found in L5178Y-R and L5178Y-S cells is not caused by a difference in ability to bind platinum complex. Enhancement of chromosomal damage and potentiation of lethal effect of cis-PAD by 0.75 mM caffeine were found in cis-PAD and UV-light-resistant L5178Y-S strain but not in cis-PAD and UV-light-sensitive L5178Y-R strain. These results suggest that the extreme sensitivity of L5178Y-R strain to cis-PAD and UV-light is caused to some extent by deficiency in a caffeine-sensitive post-replication repair system. (author)

  16. UV-vis light activated Ag decorated monodisperse TiO2 for treatment of pharmaceuticals in water

    Science.gov (United States)

    Recently, many researchers have made a lot of effort to utilize the visible light portion of the solar spectrum to activate TiO2 photocatalyst for environmental applications, such as water, air, and soil remediation. The deposition of noble metals on photocatalysts is of great in...

  17. Pathogen reduction through additive-free short-wave UV light irradiation retains the optimal efficacy of human platelet lysate for the expansion of human bone marrow mesenchymal stem cells.

    Directory of Open Access Journals (Sweden)

    Sabrina Viau

    Full Text Available We recently developed and characterized a standardized and clinical grade human Platelet Lysate (hPL that constitutes an advantageous substitute for fetal bovine serum (FBS for human mesenchymal stem cell (hMSC expansion required in cell therapy procedures, avoiding xenogenic risks (virological and immunological and ethical issues. Because of the progressive use of pathogen-reduced (PR labile blood components, and the requirement of ensuring the viral safety of raw materials for cell therapy products, we evaluated the impact of the novel procedure known as THERAFLEX UV-Platelets for pathogen reduction on hPL quality (growth factors content and efficacy (as a medium supplement for hMSC expansion. This technology is based on short-wave ultraviolet light (UV-C that induces non-reversible damages in DNA and RNA of pathogens while preserving protein structures and functions, and has the main advantage of not needing the addition of any photosensitizing additives (that might secondarily interfere with hMSCs.We applied the THERAFLEX UV-Platelets procedure on fresh platelet concentrates (PCs suspended in platelet additive solution and prepared hPL from these treated PCs. We compared the quality and efficacy of PR-hPL with the corresponding non-PR ones. We found no impact on the content of five cytokines tested (EGF, bFGF, PDGF-AB, VEGF and IGF-1 but a significant decrease in TGF-ß1 (-21%, n = 11, p<0.01. We performed large-scale culture of hMSCs from bone marrow (BM during three passages and showed that hPL or PR-hPL at 8% triggered comparable BM-hMSC proliferation as FBS at 10% plus bFGF. Moreover, after proliferation of hMSCs in an hPL- or PR-hPL-containing medium, their profile of membrane marker expression, their clonogenic potential and immunosuppressive properties were maintained, in comparison with BM-hMSCs cultured under FBS conditions. The potential to differentiate towards the adipogenic and osteogenic lineages of hMSCs cultured in parallel

  18. Pathogen reduction through additive-free short-wave UV light irradiation retains the optimal efficacy of human platelet lysate for the expansion of human bone marrow mesenchymal stem cells.

    Science.gov (United States)

    Viau, Sabrina; Chabrand, Lucie; Eap, Sandy; Lorant, Judith; Rouger, Karl; Goudaliez, Francis; Sumian, Chryslain; Delorme, Bruno

    2017-01-01

    We recently developed and characterized a standardized and clinical grade human Platelet Lysate (hPL) that constitutes an advantageous substitute for fetal bovine serum (FBS) for human mesenchymal stem cell (hMSC) expansion required in cell therapy procedures, avoiding xenogenic risks (virological and immunological) and ethical issues. Because of the progressive use of pathogen-reduced (PR) labile blood components, and the requirement of ensuring the viral safety of raw materials for cell therapy products, we evaluated the impact of the novel procedure known as THERAFLEX UV-Platelets for pathogen reduction on hPL quality (growth factors content) and efficacy (as a medium supplement for hMSC expansion). This technology is based on short-wave ultraviolet light (UV-C) that induces non-reversible damages in DNA and RNA of pathogens while preserving protein structures and functions, and has the main advantage of not needing the addition of any photosensitizing additives (that might secondarily interfere with hMSCs). We applied the THERAFLEX UV-Platelets procedure on fresh platelet concentrates (PCs) suspended in platelet additive solution and prepared hPL from these treated PCs. We compared the quality and efficacy of PR-hPL with the corresponding non-PR ones. We found no impact on the content of five cytokines tested (EGF, bFGF, PDGF-AB, VEGF and IGF-1) but a significant decrease in TGF-ß1 (-21%, n = 11, p<0.01). We performed large-scale culture of hMSCs from bone marrow (BM) during three passages and showed that hPL or PR-hPL at 8% triggered comparable BM-hMSC proliferation as FBS at 10% plus bFGF. Moreover, after proliferation of hMSCs in an hPL- or PR-hPL-containing medium, their profile of membrane marker expression, their clonogenic potential and immunosuppressive properties were maintained, in comparison with BM-hMSCs cultured under FBS conditions. The potential to differentiate towards the adipogenic and osteogenic lineages of hMSCs cultured in parallel in the

  19. Two-dimensional molybdenum disulphide nanoflakes synthesized by liquid-solid phase reaction method: regenerative photocatalytic performance under UV-visible light irradiation by advance oxidation process

    Science.gov (United States)

    Afsar, M. F.; Rafiq, M. A.; Siddique, Fizza; Saira, F.; Chaudhary, M. M.; Hasan, M. M.; Tok, A. I. Y.

    2018-05-01

    Molybdenum disulphide (MoS2) nanoflakes were prepared through liquid-solid phase reaction technique. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM) analysis revealed the formation of pure, polycrystalline, hexagonal phase of MoS2 nanoflakes. The texture coefficient (T{c}hkl) analysis showed that (100) plane was preferentially oriented. The specific surface area of the nanoflakes was 21 m2 g‑1 as determined using Brunaure-Emmett-Teller (BET) technique. A band gap of ∼2.05 eV for MoS2 nanoflakes was estimated from UV-visible spectrum. Regenerative photocatalytic activity of MoS2 nanoflakes was assessed by degrading methylene blue (MB) and safranin-o (SO) dyes under UV-visible light irradiation. Under light irradiation, degradation efficiency for MB was ∼99.58% in 100 min while for SO it was ∼99.89% in 70 min. The MoS2 nanoflakes exhibited excellent photocatalytic performance and good stability in a wide pH range (3–11). MoS2 nanoflakes showed a high reaction rate constant (k app ) for SO ∼ 0.104 49 min‑1 and MB ∼ 0.092 18 min‑1 as compared to other MoS2 nanostructures. The obtained exceptional photocatalytic performance of MoS2 nanoflakes offers potential applications for the treatment of polluted water as well as in other correlated fields.

  20. Toxicity of TiO2, in nanoparticle or bulk form to freshwater and marine microalgae under visible light and UV-A radiation.

    Science.gov (United States)

    Sendra, M; Moreno-Garrido, I; Yeste, M P; Gatica, J M; Blasco, J

    2017-08-01

    Use of titanium dioxide nanoparticles (TiO 2 NPs) has become a part of our daily life and the high environmental concentrations predicted to accumulate in aquatic ecosystems are cause for concern. Although TiO 2 has only limited reactivity, at the nanoscale level its physico-chemical properties and toxicity are different compared with bulk material. Phytoplankton is a key trophic level in fresh and marine ecosystems, and the toxicity provoked by these nanoparticles can affect the structure and functioning of ecosystems. Two microalgae species, one freshwater (Chlamydomonas reinhardtii) and the other marine (Phaeodactylum tricornutum), have been selected for testing the toxicity of TiO 2 in NP and conventional bulk form and, given its photo-catalytic properties, the effect of UV-A was also checked. Growth inhibition, quantum yield reduction, increase of intracellular ROS production, membrane cell damage and production of exo-polymeric substances (EPS) were selected as variables to measure. TiO 2 NPs and bulk TiO 2 show a relationship between the size of agglomerates and time in freshwater and saltwater, but not in ultrapure water. Under two treatments, UV-A (6 h per day) and no UV-A exposure, NPs triggered stronger cytotoxic responses than bulk material. TiO 2 NPs were also associated with greater production of reactive oxygen species and damage to membrane. However, microalgae exposed to TiO 2 NPs and bulk TiO 2 under UV-A were found to be more sensitive than in the visible light condition. The marine species (P. tricornutum) was more sensitive than the freshwater species, and higher Ti internalization was measured. Exopolymeric substances (EPS) were released from microalgae in the culture media, in the presence of TiO 2 in both forms. This may be a possible defense mechanism by these cells, which would enhance processes of homoagglomeration and settling, and thus reduce bioavailability. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. COMPARATIVE ANALYSIS USING DIPIRONA DEGRADATION PROCESS WITH PHOTO-FENTON UV-C LIGHT AND SOLAR RADIATION

    Directory of Open Access Journals (Sweden)

    Daniella Carla Napoleão

    2015-01-01

    Full Text Available The contamination of water bodies is a major concern on the part of scientists from different parts of the world. Domestic and industrial activities are the cause of the daily pouring of various types of pollutants which are in most cases resistant to conventional treatments of waters. Among the contaminants, especially noteworthy are the drugs in which it is found that 50% to 90% are discarded without treatment. The concerns about these substances are the adverse effects to human health and animals, especially in aquatic environments. The advanced oxidation processes (AOP have been studied and applied as an efficient alternative treatment, in order that it can be applied to the degradation of the different pollutants, considering that can generate hydroxyl radicals, highly reactive even somewhat selective. This study evaluated the efficiency of the photo-Fenton process using UV-C radiation and sunlight to degradation of the drug dipyrone in aqueous solution contaminated with the active ingredient of the drug at a concentration of 20 mg.L-1. Assays were performed with 50 mL aliquots of the solution following 23 factorial designs with central point, and the variables studied: addition of H2O2, adding FeSO4.7H2O and time. The detection and quantification of dipyrone before and after the AOP was performed by high performance liquid chromatography (HPLC and verified that about DE100% degradation of the compound was obtained.

  2. Photodegradation of phenol by N-Doped TiO{sub 2} anatase/rutile nanorods assembled microsphere under UV and visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Mohamed, Mohamad Azuwa [Advanced Membrane Technology Research Centre, UniversitiTeknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia); Faculty of Petroleum and Renewable Energy Engineering, UniversitiTeknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia); Salleh, W.N.W., E-mail: hayati@petroleum.utm.my [Advanced Membrane Technology Research Centre, UniversitiTeknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia); Faculty of Petroleum and Renewable Energy Engineering, UniversitiTeknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia); Jaafar, Juhana; Ismail, A.F.; Nor, Nor Azureen Mohamad [Advanced Membrane Technology Research Centre, UniversitiTeknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia); Faculty of Petroleum and Renewable Energy Engineering, UniversitiTeknologi Malaysia, 81310 Skudai, Johor Bahru (Malaysia)

    2015-07-15

    N-doped TiO{sub 2} anatase/rutile nanorods assembled microspheres were successfully synthesized via a simple and direct sol–gel method containing titanium-n-butoxide Ti(OBu){sub 4} as a precursor material, nitric acid as a catalyst, and isopropanol as a solvent. By manipulating calcination temperature, the photocatalyst consisting of different phase compositions of anatase and rutile was obtained. The prepared TiO{sub 2} nanoparticles were characterized by means of x-ray diffraction (XRD), field emission scanning microscope (FESEM), atomic force microscopy (AFM), Brunauer–Emmett–Teller (BET) analysis, UV–Vis–NIR spectroscopy, and fourier transform infrared (FTIR). The results from UV–Vis–NIR spectroscopy and FTIR revealed the direct incorporation of nitrogen in TiO{sub 2} lattice since visible absorption capability was observed at 400–600 nm. XPS study indicated the incorporation of nitrogen as dopant in TiO{sub 2} at binding energies of 396.8, 397.5, 398.7, 399.8, and 401 eV. Calcination temperature was observed to have a great influence on the photocatalytic activity of the TiO{sub 2} nanorods. The photocatalytic activity of the prepared mixed phase of anatase/rutile TiO{sub 2} nanoparticles was measured by photodegradation phenol in an aqueous solution under UV and visible irradiations. N-doped TiO{sub 2} anatase/rutile nanorods assembled microsphere (consists of 38.3% anatase and 61.7% rutile) that was prepared at 400 °C exhibited the highest photocatalytic activity after irradiated under visible and UV light for 540 min. The high performance of photocatalyst materials could be obtained by adopting a judicious combination of anatase/rutile prepared at optimum calcination conditions. - Highlights: • Synthesis of N-Doped TiO{sub 2} Anatase/Rutile Nanorods via simple preparation method. • Direct incorporation of HNO{sub 3} as the nitrogen dopant source. • The photocatalytic properties were studied upon UV and visible light irradiation.

  3. Photodegradation of phenol by N-Doped TiO2 anatase/rutile nanorods assembled microsphere under UV and visible light irradiation

    International Nuclear Information System (INIS)

    Mohamed, Mohamad Azuwa; Salleh, W.N.W.; Jaafar, Juhana; Ismail, A.F.; Nor, Nor Azureen Mohamad

    2015-01-01

    N-doped TiO 2 anatase/rutile nanorods assembled microspheres were successfully synthesized via a simple and direct sol–gel method containing titanium-n-butoxide Ti(OBu) 4 as a precursor material, nitric acid as a catalyst, and isopropanol as a solvent. By manipulating calcination temperature, the photocatalyst consisting of different phase compositions of anatase and rutile was obtained. The prepared TiO 2 nanoparticles were characterized by means of x-ray diffraction (XRD), field emission scanning microscope (FESEM), atomic force microscopy (AFM), Brunauer–Emmett–Teller (BET) analysis, UV–Vis–NIR spectroscopy, and fourier transform infrared (FTIR). The results from UV–Vis–NIR spectroscopy and FTIR revealed the direct incorporation of nitrogen in TiO 2 lattice since visible absorption capability was observed at 400–600 nm. XPS study indicated the incorporation of nitrogen as dopant in TiO 2 at binding energies of 396.8, 397.5, 398.7, 399.8, and 401 eV. Calcination temperature was observed to have a great influence on the photocatalytic activity of the TiO 2 nanorods. The photocatalytic activity of the prepared mixed phase of anatase/rutile TiO 2 nanoparticles was measured by photodegradation phenol in an aqueous solution under UV and visible irradiations. N-doped TiO 2 anatase/rutile nanorods assembled microsphere (consists of 38.3% anatase and 61.7% rutile) that was prepared at 400 °C exhibited the highest photocatalytic activity after irradiated under visible and UV light for 540 min. The high performance of photocatalyst materials could be obtained by adopting a judicious combination of anatase/rutile prepared at optimum calcination conditions. - Highlights: • Synthesis of N-Doped TiO 2 Anatase/Rutile Nanorods via simple preparation method. • Direct incorporation of HNO 3 as the nitrogen dopant source. • The photocatalytic properties were studied upon UV and visible light irradiation. • The optimum calcination temperature is 400 °C for

  4. A plant gene for photolyase: an enzyme catalyzing the repair of UV-light-induced DNA damage

    International Nuclear Information System (INIS)

    Batschauer, A.

    1993-01-01

    Photolyases are thought to be critical components of the defense of plants against damage to DNA by solar ultraviolet light, but nothing is known about their molecular or enzymatic nature. The molecular cloning of a photolyase from mustard (Sinapis alba) described here is intended to increase the knowledge about this important repair mechanism in plant species at a molecular level. The gene encodes a polypeptide of 501 amino acids with a predicted molecular mass of 57 kDa. There is a strong sequence similarity to bacterial and yeast photolyases, with a close relationship to enzymes with a deazaflavin chromophor. The plant photolyase is shown to be functional in Escherichia coli which also indicates conservation of photolyases during evolution. It is demonstrated that photolyase expression in plants is light induced, thus providing good evidence for the adaptation of plants to their environment in order to diminish the harmful effects of sunlight. (author)

  5. Sensitization by UV light of α-Al{sub 2}O{sub 3}:C polycrystalline detectors

    Energy Technology Data Exchange (ETDEWEB)

    Meira B, L. C.; Rubio F, H.; Neres de A, E. [Centro de Desenvolvimento da Tecnologia Nuclear - CNEN, Laboratorio de Dosimetria Termoluminicente, Av. Antonio Carlos 6627, Campus UFMG, CEP 31270-901, Belo Horizonte (Brazil); Santos, A., E-mail: hrf@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear - CNEN, Laboratorio de Microesferas Gel, Av. Antonio Carlos 6627, Campus UFMG, CEP 31270-901, Belo Horizonte (Brazil)

    2014-08-15

    This paper describes an increase in sensitivity to gamma and beta radiation on α-Al{sub 2}O{sub 3}:C polycrystalline detector, which has been produced by a sol-gel process, following previous exposure to ultraviolet light. The increased sensitivity of the detector as a function of the exposure time and ultraviolet wavelength was studied. Since the main luminescent centers have emission peaks at different wavelengths, selective measurements of thermoluminescent emission intensity were done, in order to investigate the possible conversion of centers as a result of the exposition to ultraviolet light. Experimental results indicate that the nature and parameters of the luminescent centers in α-Al{sub 2}O{sub 3}:C sol-gel material can be very different of those in α-Al{sub 2}O{sub 3}:C single crystal. (author)

  6. Production of organic compounds in plasmas: A comparison among electric sparks, laser-induced plasmas and UV light

    Science.gov (United States)

    Scattergood, T. W.; Mckay, C. P.; Borucki, W. J.; Giver, L. P.; Vanghyseghem, H.; Parris, J. E.; Miller, S. L.

    1991-01-01

    In order to study the production of organic compounds in plasmas (and shocks), various mixtures of N2, CH4, and H2, modeling the atmosphere of Titan, were exposed to discrete sparks, laser-induced plasmas (LIP) and ultraviolet light. The yields of HCN and simple hydrocarbons were measured and compared to those calculated from a simple quenched thermodynamic equilibrium model. The agreement between experiment and theory was fair for HCN and C2H2. However, the yields of C2H6 and other hydrocarbons were much higher than those predicted by the model. Our experiments suggest that photolysis by ultraviolet light from the plasma is an important process in the synthesis. This was confirmed by the photolysis of gas samples exposed to the light, but not to the plasma or shock waves. The results of these experiments demonstrate that, in addition to the well-known efficient synthesis of organic compounds in plasmas, the yields of saturated species, e.g., ethane, may be higher than predicted by theory and that LIP provide a convenient and clean way of simulating planetary lightning and impact plasmas in the laboratory.

  7. Lighting.

    Energy Technology Data Exchange (ETDEWEB)

    United States. Bonneville Power Administration.

    1992-09-01

    Since lighting accounts for about one-third of the energy used in commercial buildings, there is opportunity to conserve. There are two ways to reduce lighting energy use: modify lighting systems so that they used less electricity and/or reduce the number of hours the lights are used. This booklet presents a number of ways to do both. Topics covered include: reassessing lighting levels, reducing lighting levels, increasing bulb & fixture efficiency, using controls to regulate lighting, and taking advantage of daylight.

  8. 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.

  9. Molecular Engineering of UV/Vis Light-Emitting Diode (LED)-Sensitive Donor-π-Acceptor-Type Sulfonium Salt Photoacid Generators: Design, Synthesis, and Study of Photochemical and Photophysical Properties.

    Science.gov (United States)

    Wu, Xingyu; Jin, Ming; Xie, Jianchao; Malval, Jean-Pierre; Wan, Decheng

    2017-11-07

    A series of donor-π-acceptor-type sulfonium salt photoacid generators (PAGs) were designed and synthesized by systematically changing electron-donating groups, π-conjugated systems, electron-withdrawing groups, and the number of branches through molecular engineering. These PAGs can effectively decompose under UV/Vis irradiation from a light-emitting diode (LED) light source because of the matching absorption and emitting spectra of the LEDs. The absorption and acid-generation properties of these sulfonium salts were elucidated by UV/Vis spectroscopy and so forth. Results indicated that the PAG performance benefited from the introduction of strong electron-donating groups, specific π-conjugated structures, certain electron-withdrawing groups, or two-branched structures. Most sulfonium salts showed potential as photoinitiators under irradiation by a wide variety of UV and visible LEDs. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Predawn and high intensity application of supplemental blue light decreases the quantum yield of PSII and enhances the amount of phenolic acids, flavonoids, and pigments in Lactuca sativa.

    Directory of Open Access Journals (Sweden)

    Theoharis eOuzounis

    2015-02-01

    Full Text Available To evaluate the effect of blue light intensity and timing, two cultivars of lettuce [Lactuca sativa cv. ’Batavia’ (green and cv. ‘Lollo Rossa’ (red] were grown in a greenhouse compartment in late winter under natural light and supplemental high pressure sodium (SON-T lamps yielding 90 (±10 µmol m-2 s-1 for up to 20 hr, but never between 17:00 and 21:00. The temperature in the greenhouse compartments was 22/11°C day/night, respectively. The five light-emitting diode (LED light treatments were Control (no blue addition, 1B 06-08 (Blue light at 45 µmol m-2 s-1 from 06:00 to 08:00, 1B 21-08 (Blue light at 45 µmol m-2 s-1 from 21:00 to 08:00, 2B 17-19 (Blue at 80 µmol m-2 s-1 from 17:00 to 19:00, and (1B 17-19 Blue at 45 µmol m-2 s-1from 17:00 to 19:00. Total fresh and dry weight was not affected with additional blue light; however, plants treated with additional blue light were more compact. The stomatal conductance in the green lettuce cultivar was higher for all treatments with blue light compared to the Control. Photosynthetic yields measured with chlorophyll fluorescence showed different response between the cultivars; in red lettuce, the quantum yield of PSII decreased and the yield of non-photochemical quenching increased with increasing blue light, whereas in green lettuce no difference was observed. Quantification of secondary metabolites showed that all four treatments with additional blue light had higher amount of pigments, phenolic acids, and flavonoids compared to the Control. The effect was more prominent in red lettuce, highlighting that the results vary among treatments and compounds. Our results indicate that not only high light level triggers photoprotective heat dissipation in the plant, but also the specific spectral composition of the light itself at low intensities. However, these plant responses to light are cultivar dependent.

  11. Predawn and high intensity application of supplemental blue light decreases the quantum yield of PSII and enhances the amount of phenolic acids, flavonoids, and pigments in Lactuca sativa.

    Science.gov (United States)

    Ouzounis, Theoharis; Razi Parjikolaei, Behnaz; Fretté, Xavier; Rosenqvist, Eva; Ottosen, Carl-Otto

    2015-01-01

    To evaluate the effect of blue light intensity and timing, two cultivars of lettuce [Lactuca sativa cv. "Batavia" (green) and cv. "Lollo Rossa" (red)] were grown in a greenhouse compartment in late winter under natural light and supplemental high pressure sodium (SON-T) lamps yielding 90 (±10) μmol m(-2) s(-1) for up to 20 h, but never between 17:00 and 21:00. The temperature in the greenhouse compartments was 22/11°C day/night, respectively. The five light-emitting diode (LED) light treatments were Control (no blue addition), 1B 06-08 (Blue light at 45 μmol m(-2) s(-1) from 06:00 to 08:00), 1B 21-08 (Blue light at 45 μmol m(-2) s(-1) from 21:00 to 08:00), 2B 17-19 (Blue at 80 μmol m(-2) s(-1) from 17:00 to 19:00), and 1B 17-19 (Blue at 45 μmol m(-2) s(-1) from 17:00 to 19:00). Total fresh and dry weight was not affected with additional blue light; however, plants treated with additional blue light were more compact. The stomatal conductance in the green lettuce cultivar was higher for all treatments with blue light compared to the Control. Photosynthetic yields measured with chlorophyll fluorescence showed different response between the cultivars; in red lettuce, the quantum yield of PSII decreased and the yield of non-photochemical quenching increased with increasing blue light, whereas in green lettuce no difference was observed. Quantification of secondary metabolites showed that all four treatments with additional blue light had higher amount of pigments, phenolic acids, and flavonoids compared to the Control. The effect was more prominent in red lettuce, highlighting that the results vary among treatments and compounds. Our results indicate that not only high light level triggers photoprotective heat dissipation in the plant, but also the specific spectral composition of the light itself at low intensities. However, these plant responses to light are cultivar dependent.

  12. Predawn and high intensity application of supplemental blue light decreases the quantum yield of PSII and enhances the amount of phenolic acids, flavonoids, and pigments in Lactuca sativa

    Science.gov (United States)

    Ouzounis, Theoharis; Razi Parjikolaei, Behnaz; Fretté, Xavier; Rosenqvist, Eva; Ottosen, Carl-Otto

    2015-01-01

    To evaluate the effect of blue light intensity and timing, two cultivars of lettuce [Lactuca sativa cv. “Batavia” (green) and cv. “Lollo Rossa” (red)] were grown in a greenhouse compartment in late winter under natural light and supplemental high pressure sodium (SON-T) lamps yielding 90 (±10) μmol m−2 s−1 for up to 20 h, but never between 17:00 and 21:00. The temperature in the greenhouse compartments was 22/11°C day/night, respectively. The five light-emitting diode (LED) light treatments were Control (no blue addition), 1B 06-08 (Blue light at 45 μmol m−2 s−1 from 06:00 to 08:00), 1B 21-08 (Blue light at 45 μmol m−2 s−1 from 21:00 to 08:00), 2B 17-19 (Blue at 80 μmol m−2 s−1 from 17:00 to 19:00), and 1B 17-19 (Blue at 45 μmol m−2 s−1 from 17:00 to 19:00). Total fresh and dry weight was not affected with additional blue light; however, plants treated with additional blue light were more compact. The stomatal conductance in the green lettuce cultivar was higher for all treatments with blue light compared to the Control. Photosynthetic yields measured with chlorophyll fluorescence showed different response between the cultivars; in red lettuce, the quantum yield of PSII decreased and the yield of non-photochemical quenching increased with increasing blue light, whereas in green lettuce no difference was observed. Quantification of secondary metabolites showed that all four treatments with additional blue light had higher amount of pigments, phenolic acids, and flavonoids compared to the Control. The effect was more prominent in red lettuce, highlighting that the results vary among treatments and compounds. Our results indicate that not only high light level triggers photoprotective heat dissipation in the plant, but also the specific spectral composition of the light itself at low intensities. However, these plant responses to light are cultivar dependent. PMID:25767473

  13. 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.