WorldWideScience

Sample records for acute uv irradiation

  1. Influence of melanocytes in the ex-vivo reconstructed epidermal melanin unit following an acute UV irradiation

    Influence of melanocytes in skin pigmentation is well documented, however its photo-protective role has given rise to controversy. The role of melanocytes have been investigated on reconstructed epidermis with 100 % of keratinocytes or 95 % of keratinocytes and 5 % of melanocytes. In a first time, the effect of an acute UVB dose has been studied on both reconstructed epidermis, next we have investigated UVA and UVA+B effects on these epidermis. Following irradiation, the presence of melanocytes in reconstructed epidermis protects against apoptosis without protecting significantly against DNA damage formation (CPD, 6-4PP) and protects against UV-induced unbalance of the SOD/catalase ratio (antioxidants enzymes). On the contrary, the presence of melanocytes in reconstructed epidermis amplifies lipids and proteins oxidations but seems to protect against DNA oxidations. Melanocytes differ from keratinocytes by their melanin content and their more important concentration in polyunsaturated fatty acids. To evaluate what is the part of melanin and the part of polyunsaturated fatty acids in epidermal UV responses, reconstructed epidermis with keratinocytes have been supplemented with polyunsaturated fatty acid. This study indicates that polyunsaturated fatty acids are responsible for lipids and proteins oxidations and that melanin protect against DNA oxidation induced by lipid peroxidation. All these studies demonstrate that, model of reconstructed epidermis and epidermis in-vivo have the same behaviour following UV irradiation. In the last part, sunscreens and antioxidants have been tested on reconstructed epidermis and have demonstrated that model of reconstructed epidermis is suitable for photo-protective molecules screening. (author)

  2. Influence of melanocytes in the ex-vivo reconstructed epidermal melanin unit following an acute UV irradiation; Role des melanocytes dans l'unite epidermique de melanisation reconstruite ex-vivo apres une irradiation UV aigue

    Cario-Andre, M

    2000-11-15

    Influence of melanocytes in skin pigmentation is well documented, however its photo-protective role has given rise to controversy. The role of melanocytes have been investigated on reconstructed epidermis with 100 % of keratinocytes or 95 % of keratinocytes and 5 % of melanocytes. In a first time, the effect of an acute UVB dose has been studied on both reconstructed epidermis, next we have investigated UVA and UVA+B effects on these epidermis. Following irradiation, the presence of melanocytes in reconstructed epidermis protects against apoptosis without protecting significantly against DNA damage formation (CPD, 6-4PP) and protects against UV-induced unbalance of the SOD/catalase ratio (antioxidants enzymes). On the contrary, the presence of melanocytes in reconstructed epidermis amplifies lipids and proteins oxidations but seems to protect against DNA oxidations. Melanocytes differ from keratinocytes by their melanin content and their more important concentration in polyunsaturated fatty acids. To evaluate what is the part of melanin and the part of polyunsaturated fatty acids in epidermal UV responses, reconstructed epidermis with keratinocytes have been supplemented with polyunsaturated fatty acid. This study indicates that polyunsaturated fatty acids are responsible for lipids and proteins oxidations and that melanin protect against DNA oxidation induced by lipid peroxidation. All these studies demonstrate that, model of reconstructed epidermis and epidermis in-vivo have the same behaviour following UV irradiation. In the last part, sunscreens and antioxidants have been tested on reconstructed epidermis and have demonstrated that model of reconstructed epidermis is suitable for photo-protective molecules screening. (author)

  3. Photoluminescence of trypsin after UV-irradiation

    For study purposes of the primary effects of UV light the photoluminescence of trypsin was investigated before and after UV irradiation (lambda = 254 nm). The results were compared with the corresponding relations at equimolar mixtures of the constituent amino acids. The increase of the absorption in the region between 230 nm and 400 nm at UV irradiation of trypsin in aqueous solution is primarily attributed to the ionization of tyrosine. The fluorescence is strongly quenched mainly due to the ionized tyrosine residues. The results are discussed in connection with previous investigations on radical formation and inactivation of trypsin after UV irradiation. (orig.)

  4. DNA damage caused by UV- and near UV-irradiation

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

  5. Reconstruction of solar UV irradiance since 1974

    Krivova, N. A.; Solanki, S. K.; Wenzler, T.; Podlipnik, B.

    2009-01-01

    Variations of the solar UV irradiance are an important driver of chemical and physical processes in the Earth's upper atmosphere and may also influence global climate. Here we reconstruct solar UV irradiance in the range 115-400 nm over the period 1974-2007 by making use of the recently developed empirical extension of the SATIRE models employing SUSIM data. The evolution of the solar photospheric magnetic flux, which is a central input to the model, is described by the magnetograms and conti...

  6. OMEGA: a 24 beam uv irradiation facility

    We report the recent completion of the uv upconversion (351 nm) of all 24 beams of the OMEGA laser which provides a unique short wavelength symmetrical irradiation facility for direct drive laser fusion experiments. Details of the characterization of illumination uniformity and initial implosion experiments will be described

  7. Global irradiance calibration of multifilter UV radiometers

    Piedehierro, A. A.; Cancillo, M. L.; Serrano, A.; Antón, M.; Vilaplana, J. M.

    2016-01-01

    It is well known that the amount of ultraviolet solar radiation (UV) reaching the Earth's surface is governed by stratospheric ozone, which has exhibited notable variations since the late 1970s. A thorough monitoring of UV radiation requires long-term series of accurate measurements worldwide, and to keep track of its evolution, it is essential to use high-quality instrumentation with an excellent long-term performance capable of detecting low UV signal. There are several UV monitoring networks worldwide based on multifilter UV radiometers; however, there is no general agreement about the most suitable methodology for the global irradiance calibration of these instruments. This paper aims to compare several calibration methods and to analyze their behavior for different ranges of solar zenith angle (SZA). Four methods are studied: the two currently most frequently used methods referred to in the literature and two new methods that reduce systematic errors in calibrated data at large solar zenith angles. The results evidence that proposed new methods show a clear improvement compared to the classic approaches at high SZA, especially for channels 305 and 320 nm. These two channels are of great interest for calculating the total ozone column and other products such as dose rates of biological interest in the UV range (e.g., the erythemal dose).

  8. Repair of nonreplicating UV-irradiated DNA

    Martin, S.J.; Hays, J.B.

    1986-05-01

    Repair of irradiated phage lambda DNA in E. coli has been studied by a repressed-infection system: superinfection of homoimmune lysogenic bacteria; assay for restoration of transcribility to phage-encoded lac genes; extraction of DNA and assay for infectivity in transfection of uvrB/sup -/ recA/sup -/ recB/sup -/ spheroplasts, and for removal of cyclobutane pyrimidine dimers (CBP-dimers) by UV-endonuclease treatment and alkaline sedimentation. In uvr/sup +/ repressed infections with 254-nm irradiated phages (60 J/m/sup 2/) lac transcription was rapidly returned to undamaged levels, concomitant with restoration of infectivity and removal of CBP-dimers. In uvrD/sup -/ cells, the frequency of phage gene inactivation corresponded to the estimated frequency of CBP-dimers per gene. In uvrA/sup -/ bacteria, however, lac expression was only 1/10 to 1/3 of that predicted by the expected frequency of gene inactivation, as if damage elsewhere affected transcription; recovery of infectivity and removal of CBP-dimers was almost completely inhibited. lac/sup +/ and lacUV5 phages, expected to respond oppositely to changes in superhelical density, were constructed as probes for topological changes during DNA repair. The assays for transfection infectivity and CBP-dimer-removal have been extended to studies of repair of UV-irradiated phage DNA injected into oocytes of the frog Xenopus laevis.

  9. Repair of nonreplicating UV-irradiated DNA

    Repair of irradiated phage λ DNA in E. coli has been studied by a repressed-infection system: superinfection of homoimmune lysogenic bacteria; assay for restoration of transcribility to phage-encoded lac genes; extraction of DNA and assay for infectivity in transfection of uvrB- recA- recB- spheroplasts, and for removal of cyclobutane pyrimidine dimers (CBP-dimers) by UV-endonuclease treatment and alkaline sedimentation. In uvr+ repressed infections with 254-nm irradiated phages (60 J/m2) lac transcription was rapidly returned to undamaged levels, concomitant with restoration of infectivity and removal of CBP-dimers. In uvrD- cells, the frequency of phage gene inactivation corresponded to the estimated frequency of CBP-dimers per gene. In uvrA- bacteria, however, lac expression was only 1/10 to 1/3 of that predicted by the expected frequency of gene inactivation, as if damage elsewhere affected transcription; recovery of infectivity and removal of CBP-dimers was almost completely inhibited. lac+ and lacUV5 phages, expected to respond oppositely to changes in superhelical density, were constructed as probes for topological changes during DNA repair. The assays for transfection infectivity and CBP-dimer-removal have been extended to studies of repair of UV-irradiated phage DNA injected into oocytes of the frog Xenopus laevis

  10. Quality assessment of solar UV irradiance measured with array spectroradiometers

    L. Egli; Gröbner, J.; Hülsen, G.; Bachmann, L; M. Blumthaler; Dubard, J.; M. Khazova; R. Kift; K. Hoogendijk; A. Serrano; Smedley, A. R. D.; J.-M. Vilaplana

    2015-01-01

    The reliable quantification of ultraviolet (UV) radiation at the Earth's surface requires accurate measurements of spectral global solar UV irradiance in order to determine the UV exposure to human skin and to understand long-term trends in this parameter. Array spectroradiometers are small, light, robust and cost effective instruments and are increasingly used for spectral irradiance measurements. Within the European EMRP-ENV03 project "Solar UV", new devices, guidelines, a...

  11. Change of erythrocytes and thrombocytes aggregation under UV-irradiation

    It is shown, that in blood serum during UV-irradiation lipid peroxide photooxidation takes place. It has been established, that the reaction products inhibit aggregation of native trombocytes, induced by ADP. UV-irradiation of plasma or serum albumin causes the increase of their ability to induce the formation of erythrocytic stacks. It is assumed that in plasma during UV-irradiation aggregates of albumin molecules are formed, being bound by erythrocytes in the stacks

  12. UV Irradiance Enhancements by Scattering of Solar Radiation from Clouds

    Uwe Feister

    2015-08-01

    Full Text Available Scattering of solar radiation by clouds can reduce or enhance solar global irradiance compared to cloudless-sky irradiance at the Earth’s surface. Cloud effects to global irradiance can be described by Cloud Modification Factors (CMF. Depending on strength and duration, irradiance enhancements affect the energy balance of the surface and gain of solar power for electric energy generation. In the ultraviolet region, they increase the risk for damage to living organisms. Wavelength-dependent CMFs have been shown to reach 1.5 even in the UV-B region at low altitudes. Ground-based solar radiation measurements in the high Andes region at altitudes up to 5917 m a.s.l showed cloud-induced irradiance enhancements. While UV-A enhancements were explained by cloud scattering, both radiation scattering from clouds and Negative Ozone Anomalies (NOA have been discussed to have caused short-time enhancement of UV-B irradiance. Based on scenarios using published CMF and additional spectroradiometric measurements at a low-altitude site, the contribution of cloud scattering to the UV-B irradiance enhancement in the Andes region has been estimated. The range of UV index estimates converted from measured UV-B and UV-A irradiance and modeled cloudless-sky ratios UV-B/erythemal UV is compatible with an earlier estimate of an extreme UV index value of 43 derived for the high Andes.

  13. CaII Κ Imaging to Understand UV Irradiance Variability

    R. Kariyappa

    2000-09-01

    To identify and understand the underlying physical mechanisms of total solar and UV irradiance variability and to estimate the contribution of various chromospheric features to UV irradiance, detailed analysis of spatially resolved data is required. The various chromospheric features have been segregated and different parameters have been derived from CaII Κ Spectroheliograms of NSO/Sac Peak and Kodaikanal Observatory and compared with UV irradiance flux measured in MgII h and k lines by NOAA 9 satellite. The important results of this detailed analysis of CaII Κ Images of 1992 together with UV irradiance data will be discussed in this paper.

  14. Transmission of UV-irradiance into nectarine fruit

    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

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

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

  16. Effect of UV-C Irradiation on Nutraceuticals in Blueberries

    UV-C treatment has been shown to reduce decay of fruits after harvest. However, little information is available on the influence of UV-C illumination on changes of nutraceutical content in fruits. This study was initiated to investigate the effect of UV-C irradiation on total phenolics, total anth...

  17. Practical aspects of irradiance and energy in UV curing

    The physical properties of UV-cured materials are substantially affected by the lamp systems used to cure them. The development of the intended properties, whether a varnish, an ink, or an adhesive, can depend on how well these lamp factors are designed and managed. The four key factors of UV exposure are: UV irradiance (or intensity), spectral distribution (wavelengths) of UV, effective energy (time-integrated UV irradiance), and infrared radiation. Inks and varnishes will exhibit very different response to peak irradiance or energy, as well as to different UV spectra. The ability to identify the various lamp characteristics and match them to the optical properties of the curable materials, widens the range in which UV curing is a faster, more efficient production process. This paper explores the reasons for clearly identifying these factors for process optimization

  18. Record Solar UV Irradiance in the Tropical Andes

    DonatP.Häder

    2014-07-01

    Full Text Available High elevation, thin ozone layer, and clear sky produce intense ultraviolet (UV radiation in the tropical Andes. Recent models suggest that tropical stratospheric ozone will slightly decrease in the coming decades, potentially resulting in more UV anomalies. Data collected between 4,300-5,916 m above sea level (asl in Bolivia show how this trend could dramatically impact surface solar irradiance. During 61 days, two Eldonet dosimeters recorded extreme UV-B irradiance equivalent to a UV index (UVI of 43.3, which is the highest ground value ever reported. If they become more common, events of this magnitude may have societal and ecological implications, which make understanding the process leading to their generation critical. Our data show that this event and other major UV spikes were consistent with rising UV-B/UV-A ratios in the days to hours preceding the spikes, trajectories of negative ozone anomalies (NOAs, and radiative transfer modeling.

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

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

  20. UV irradiation responses in Giardia intestinalis.

    Einarsson, Elin; Svärd, Staffan G; Troell, Karin

    2015-07-01

    The response to ultraviolet light (UV) radiation, a natural stressor to the intestinal protozoan parasite Giardia intestinalis, was studied to deepen the understanding of how the surrounding environment affects the parasite during transmission. UV radiation at 10 mJ/cm(2) kills Giardia cysts effectively whereas trophozoites and encysting parasites can recover from UV treatment at 100 mJ/cm(2) and 50 mJ/cm(2) respectively. Staining for phosphorylated histone H2A showed that UV treatment induces double-stranded DNA breaks and flow cytometry analyses revealed that UV treatment of trophozoites induces DNA replication arrest. Active DNA replication coupled to DNA repair could be an explanation to why UV light does not kill trophozoites and encysting cells as efficiently as the non-replicating cysts. We also examined UV-induced gene expression responses in both trophozoites and cysts using RNA sequencing (RNA seq). UV radiation induces small overall changes in gene expression in Giardia but cysts show a stronger response than trophozoites. Heat shock proteins, kinesins and Nek kinases are up-regulated, whereas alpha-giardins and histones are down-regulated in UV treated trophozoites. Expression of variable surface proteins (VSPs) is changed in both trophozoites and cysts. Our data show that Giardia cysts have limited ability to repair UV-induced damage and this may have implications for drinking- and waste-water treatment when setting criteria for the use of UV disinfection to ensure safe water. PMID:25825252

  1. Quality assessment of solar UV irradiance measured with array spectroradiometers

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

    2016-04-01

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

  2. UV irradiated PVA–Ag nanocomposites for optical applications

    Graphical abstract: - Highlights: • Refractive index increases as a function of irradiation time. • Reflectance decreases with increasing exposure time to UV irradiation. • Optical energy gap decreases with increasing UV irradiation time. • SRP band intensity symmetry increases with increase of exposure time. • With increasing UV exposure interaction between Ag nanoparticles and PVA enhances. - Abstract: The present paper is focused on the in-situ prepared Poly (vinyl alcohol)–Silver (PVA–Ag) nanocomposites and tailoring their optical properties by means of UV irradiation in such a way that these can be used for anti-reflective coatings and bandpass filters. The reflectance from these irradiated nanocomposites has been found to decrease leading to the increase in refractive index (RI), with increasing UV exposure time, in the entire visible region. Decrease in optical energy gap of PVA film from 4.92 to 4.57 eV on doping with Ag nanoparticles has been observed which reduces further to 4.1 eV on exposure to UV radiations for 300 min. This decrease in optical energy gap can be correlated to the formation of charge transfer complexes within the base polymer network on embedding Ag nanoparticles, which further enhances with increasing exposure time. Such complexes may also be responsible for increased molecular density of the composite films which corresponds to decrease in reflectance corroborating the observed results

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

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

    2009-02-01

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

  4. Mean Annual UV-B Irradiance

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

  5. UV-irradiation enhances rice allelopathic potential in rhizosphere soil

    Mahmood, Khalid; Khan, Muhammad Bismillah; Song, Yuan Yuan;

    2013-01-01

    Ultraviolet-B radiation is rising continuously due to stratospheric ozone depletion over temperate latitudes. This study investigated effects of UV exposure on rice allelopathic potentials. For this purpose, two rice (Oryza sativa L.) cultivars BR-41 (high allelopathic = able to inhibit neighboring...... after UV exposure. The relative transcripts of genes (OsPAL and OsCYC1) responsible for biosynthesis of allelopathic compounds were also significantly higher after UV exposure. These results suggest that enhanced UV-irradiation levels due to ozone depletion may increase rice allelopathic potentials...

  6. Thermoluminescence sensitivity of ulexite after UV irradiation

    Highlights: •UV-induced thermoluminescence emission of Turkish ulexite was studied. •There are three groups of components. •The UV exposures were performed at controlled temperatures. -- Abstract: The effects of UV radiation on the thermoluminescence (TL) properties of natural materials, in contrast to synthetic materials, have been scarcely studied. We report on the UV-induced thermoluminescence emission of a Turkish ulexite (NaCaB5O6(OH)6·5H2O) that displays very complex TL glow curves, with at least three groups of components peaked at 130–140 °C, 240 °C and, 340 °C, wherein the last group is weaker. Such emission could be associated with structural changes in the lattice as well as alkali self-diffusion processes. The UV exposure performed at controlled temperatures (at room temperature (RT), 50 °C and 100 °C) produced a (i) different evolutions of the intensities of each maximum, which are directly related to the controlled thermal treatment; (ii) different intensity ratios among the groups of components; (iii) different activation energies (Ea) (1.13 eV for RT, 0.99 eV for 50 °C and 0.49 eV for 100 °C) calculated using the initial rise method; and (iv) similar scattering values (12.4%, 8.2% and 12.8%), which were not a function of the controlled temperature. The thermal stability tests conducted on this borate at different temperatures, based on the Tstop protocol, confirm the presence of a continuum in the distribution of the trap system with progressively increasing Ea (from 0.60 to 0.90 eV)

  7. Thermoluminescence sensitivity of ulexite after UV irradiation

    Topaksu, M., E-mail: mats@cu.edu.tr [Cukurova University, Arts-Sciences Faculty, Physics Department, 01330 Adana (Turkey); CIEMAT, Av. Complutense 22, 28040 Madrid (Spain); Correcher, V. [CIEMAT, Av. Complutense 22, 28040 Madrid (Spain); Garcia-Guinea, J. [Museo Nacional de Ciencias Naturales, (CSIC), C/José Gutiérrez Abascal 2, 28006 Madrid (Spain)

    2015-04-15

    Highlights: •UV-induced thermoluminescence emission of Turkish ulexite was studied. •There are three groups of components. •The UV exposures were performed at controlled temperatures. -- Abstract: The effects of UV radiation on the thermoluminescence (TL) properties of natural materials, in contrast to synthetic materials, have been scarcely studied. We report on the UV-induced thermoluminescence emission of a Turkish ulexite (NaCaB{sub 5}O{sub 6}(OH){sub 6}·5H{sub 2}O) that displays very complex TL glow curves, with at least three groups of components peaked at 130–140 °C, 240 °C and, 340 °C, wherein the last group is weaker. Such emission could be associated with structural changes in the lattice as well as alkali self-diffusion processes. The UV exposure performed at controlled temperatures (at room temperature (RT), 50 °C and 100 °C) produced a (i) different evolutions of the intensities of each maximum, which are directly related to the controlled thermal treatment; (ii) different intensity ratios among the groups of components; (iii) different activation energies (E{sub a}) (1.13 eV for RT, 0.99 eV for 50 °C and 0.49 eV for 100 °C) calculated using the initial rise method; and (iv) similar scattering values (12.4%, 8.2% and 12.8%), which were not a function of the controlled temperature. The thermal stability tests conducted on this borate at different temperatures, based on the T{sub stop} protocol, confirm the presence of a continuum in the distribution of the trap system with progressively increasing E{sub a} (from 0.60 to 0.90 eV)

  8. Expression of Nudix hydrolase genes in barley under UV irradiation

    Tanaka, Sayuri; Sugimoto, Manabu; Kihara, Makoto

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

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

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

  10. The cloud effects on UV irradiance modeled in Antarctica

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

  11. 1/f noise in the UV solar spectral irradiance

    Varotsos, Costas A.; Melnikova, Irina; Efstathiou, Maria N.; Tzanis, Chris

    2013-02-01

    The investigation of the intrinsic properties of the solar spectral irradiance as a function of the ultraviolet (UV) wavelength is attempted by exploiting rare observations performed at the Villard St. Pancrace station of the Lille University of Sciences and Technology ranging from 278 to 400 nm with a step of 0.05 nm every half an hour from nearly sunrise to sunset. To achieve this goal, the modern method of the detrended fluctuation analysis was applied on the solar spectral irradiance values versus wavelength. This analysis revealed that the solar incident flux at the top of the atmosphere and the solar spectral irradiance at the ground during two overcast sky days fluctuate with the UV wavelength exhibiting persistent long-range power-law behavior. More interestingly, the exponent of the power-law relationship between the fluctuations of the solar spectral irradiance versus UV wavelength at both the top of the atmosphere and the ground is consistently close to unity (of 1/f-type) throughout the day. This 1/f behavior has been detected in many complex dynamical systems, but despite much effort to derive a theory for its widespread occurrence in nature, it remains unexplained so far. According to the above-mentioned findings we speculate that the 1/f property of the incident solar UV flux at the top of the atmosphere could probably drive both the 1/f behavior depicted in the atmospheric components and the solar UV irradiance at the Earth's surface. The latter could influence the UV-sensitive biological ecosystems, giving rise to a 1/f-type variability in the biosphere, which has already been proven by recent observational data. We finally propose that Wien approximation could be multiplied by a 1/f function of wavelength (e.g., of the type of the fractional Brownian motion) in order to reproduce the aforementioned 1/f feature of the solar UV flux.

  12. Coupling UV irradiation and electrocoagulation for reclamation of urban wastewater

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

  13. Does UV irradiation affect polymer properties relevant to tissue engineering?

    Fischbach, Claudia; Tessmar, Jörg; Lucke, Andrea; Schnell, Edith; Schmeer, Georg; Blunk, Torsten; Göpferich, Achim

    2001-10-01

    For most tissue engineering approaches aiming at the repair or generation of living tissues the interaction of cells and polymeric biomaterials is of paramount importance. Prior to contact with cells or tissues, biomaterials have to be sterilized. However, many sterilization procedures such as steam autoclave or heat sterilization are known to strongly affect polymer properties. UV irradiation is used as an alternative sterilization method in many tissue engineering laboratories on a routine basis, however, potential alterations of polymer properties have not been extensively considered. In this study we investigated the effects of UV irradiation on spin-cast films made from biodegradable poly( D, L-lactic acid)-poly(ethylene glycol)-monomethyl ether diblock copolymers (Me.PEG-PLA) which have recently been developed for controlled cell-biomaterial interaction. After 2 h of UV irradiation, which is sufficient for sterilization, no alterations in cell adhesion to polymer films were detected, as demonstrated with 3T3-L1 preadipocytes. This correlated with unchanged film topography and molecular weight distribution. However, extended UV irradiation for 5-24 h elicited drastic responses regarding Me.PEG-PLA polymer properties and interactions with biological elements: Large increases in unspecific protein adsorption and subsequent cell adhesion were observed. Changes in polymer surface properties could be correlated with the observed alterations in cell/protein-polymer interactions. Atomic force microscopy analysis of polymer films revealed a marked "smoothing" of the polymer surface after UV irradiation. Investigations using GPC, 1H-NMR, mass spectrometry, and a PEG-specific colorimetric assay demonstrated that polymer film composition was time-dependently affected by exposure to UV irradiation, i.e., that large amounts of PEG were lost from the copolymer surface. The data indicate that sterilization using UV irradiation for 2 h is an appropriate technique for the

  14. Fluorine absorption in dental enamel assisted by UV irradiation

    A new method of dental fluorine prophylaxis based on the chemical reaction induced by UV irradiation in dental enamel has been presented. Fluorine ions from a gel topic can be retained to the dental apatite in the lamp-irradiated samples at about 70% and in the laser-irradiated samples at about 80% of the maximum deposited value. The 19F(p, α)16O nuclear reaction was used to measure the fluorine concentrations in the first 3μm of the enamel of healthy teeth before and after the gel topic applications with and without UV irradiation. This method of dental prevenction resolves the problem of the traditional fluorine prophylaxis which brings fluorine in the enamel without binding the apatite

  15. Tests on far UV irradiation of CVD diamond

    Barberini, L; Caria, M; Murgia, F

    2000-01-01

    We present the results of UV irradiation of samples of CVD diamonds films in terms of time response and current-voltage curves. In this paper we describe the samples and the studied method. This brings us to conclusions on the defect sites. We have extensively studied the charge up effect of the film and the influence on the detection efficiency. We find a dependence on the irradiation time and methods, which questions directly a photon detector based on synthetic diamond films.

  16. Thermoluminescence sensitivity of ulexite after UV irradiation

    Topaksu, M.; Correcher, V.; Garcia-Guinea, J.

    2015-04-01

    The effects of UV radiation on the thermoluminescence (TL) properties of natural materials, in contrast to synthetic materials, have been scarcely studied. We report on the UV-induced thermoluminescence emission of a Turkish ulexite (NaCaB5O6(OH)6·5H2O) that displays very complex TL glow curves, with at least three groups of components peaked at 130-140 °C, 240 °C and, 340 °C, wherein the last group is weaker. Such emission could be associated with structural changes in the lattice as well as alkali self-diffusion processes. The UV exposure performed at controlled temperatures (at room temperature (RT), 50 °C and 100 °C) produced a (i) different evolutions of the intensities of each maximum, which are directly related to the controlled thermal treatment; (ii) different intensity ratios among the groups of components; (iii) different activation energies (Ea) (1.13 eV for RT, 0.99 eV for 50 °C and 0.49 eV for 100 °C) calculated using the initial rise method; and (iv) similar scattering values (12.4%, 8.2% and 12.8%), which were not a function of the controlled temperature. The thermal stability tests conducted on this borate at different temperatures, based on the Tstop protocol, confirm the presence of a continuum in the distribution of the trap system with progressively increasing Ea (from 0.60 to 0.90 eV).

  17. Antarctic marine bacteria versus UV-B irradiation

    The most important stages of knowledge development in Antarctic marine microbiology, from the beginning of this century, were reviewed and systematized. Multi-annual studies from 1978 to 1988 demonstrated a great variation in total and saprophytic bacterial numbers at different sites in the Antarctic. These sites included inshore waters (Admiralty Bay), open ocean waters (Drake Passage and Bransfield Strait), and the vicinity of pack-ice in Scotia Sea. Bacterial biomass, which is highly comparable to that of other organisms, combined with many times shorter bacterial generation time, (in case of saprophytic population it amounts to 17.5 h), must have profound consequences for cold marine ecosystems of the Antarctic. Higher numbers of bacteria were found in open surface waters, down to 75 m. High transparency of oceanic offshore waters causes that UV radiation (280-400 nm) penetrates to biologically effective depths to about 50 m. The UV-B sensitivity of 25 Antarctic bacterial strains from the following various habitats: coastal waters, krill stomach, krill feaces, water ice edge, water below ice and sea ice was examined. The strains were irradiated in UV-B transparent cuvettes on an optical bench with artificial UV-B (290 nm; 1.21 W. m-2 ] during 10 hours in temperature 4oC. ATP (adenosine triphosphate), number of bacterial cells, lethal effect of UV-B and survival of bacteria, total bacterial number, biovolume and changes in biochemical/physiological properties have been estimated. The results indicated a high interspecific variability in the sensitivity against UV-B. The ATP content show at the beginning of irradiation an increase (reaching typical for individual species maximum, at 0.5 to 4 hours) and afterwards a decrease to the level above zero (also characteristic of species). We hypothesize that first anabolic processes and after that catabolic processes are destroyed by UV. Survival of the bacterial strains ranged between 0 and 3.2%. Among 25 bacterial

  18. Reductone effect on UV-irradiated starved E. coli cells

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

  19. Improved sky imaging for studies of enhanced UV irradiance

    J. M. Sabburg

    2004-10-01

    Full Text Available A recent World Meteorological Organisation report discussed the importance of continued study of the effect of clouds on the solar UV radiation reaching the earth’s surface. The report mentions that the use of all-sky imagery offers the potential to understand and quantify cloud effects more accurately. There are an increasing number of studies investigating the enhancement of surface UV irradiance, and UV actinic flux, using automated CCD and sky imagers. This paper describes new algorithms applicable to a commercially available all-sky imager (TSI-440, for research investigating cloud enhanced spectral UV irradiance. Specifically, these include three new algorithms relating to cloud amount at different spatial positions and the visible brightness of clouds surrounding the sun. A possible relationship between UV enhancement and the occurrence of near-sun cloud brightness is reported. It is found that a range of wavelength dependent intensities, from 306 to 400 nm, can occur in one day for UV enhancements. Evidence of a decreasing variation of intensity with longer wavelengths is also presented.

  20. Improved sky imaging for studies of enhanced UV irradiance

    J. M. Sabburg

    2004-01-01

    Full Text Available A recent World Meteorological Organisation report discussed the importance of continued study of the effect of clouds on the solar UV radiation reaching the earth's surface. The report mentions that the use of all-sky imagery offers the potential to understand and quantify cloud effects more accurately. There are an increasing number of studies investigating the enhancement of surface solar, UV irradiance, and UV actinic flux, using automated CCD and sky imagers. This paper describes new algorithms applicable to a commercially available all-sky imager (TSI-440, for research investigating cloud enhanced spectral UV irradiance. Specifically, these include three new algorithms relating to cloud amount at different spatial positions from 1 zenith and 2 from the solar position and 3 the visible brightness of clouds surrounding the sun. A possible relationship between UV enhancement and the occurrence of near-sun cloud brightness is reported based on this preliminary data. It is found that a range of wavelength dependent intensities, from 306 to 400 nm, can occur in one day for UV enhancements. Evidence for a possible decreasing variation of intensity with longer wavelengths is also presented.

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

    Al-Gabr, Hamid Mohammad [Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); State Key Laboratory of Environmental Sciences, and Key Laboratory of Ministry of Education for Coast and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen 361005 (China); Zheng, Tianling [State Key Laboratory of Environmental Sciences, and Key Laboratory of Ministry of Education for Coast and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen 361005 (China); Yu, Xin, E-mail: xyu@iue.ac.cn [Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China)

    2013-10-01

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

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

    The disinfection process for inactivating microorganisms at drinking water treatment plants is aimed for safety of drinking water for humans from a microorganism, such as bacteria, viruses, algae, fungi by using chlorination, ozonation, UV irradiation, etc. In the present study, a combination of two disinfectants, UV irradiation followed by chlorination, was evaluated for inactivating Aspergillus flavus under low contact time and low dosage of UV irradiation. The results indicated an inverse correlation between the inactivation of A. flavus by using UV irradiation only or chlorination alone. By using UV radiation, the 2 log10 control of A. flavus was achieved after 30 s of irradiation, while chlorination was observed to be more effective than UV, where the 2 log was achieved at chlorine concentration of 0.5, 1, 2 and 3 mg/l, in contact time of 60, 5, 1 and 1 min, respectively. However, combined use (UV irradiation followed by chlorination) was more effective than using either UV or chlorination alone; 5 s UV irradiation followed by chlorination produced 4 log10 reduction of A. flavus at chlorine concentrations of 2 and 3 mg/l under a contact time of 15 min. The results indicated that efficiency of UV irradiation improves when followed by chlorination at low concentrations. - Highlights: • As a disinfectant, chlorine is more effective than UV in inactivating Aspergillus flavus. • As a combined method, UV irradiation followed by chlorination shows high efficiency. • UV irradiation can improve effectiveness of chlorination in reducing Aspergillus flavus

  3. Electrical properties of pulsed UV laser irradiated amorphous carbon

    Y. Miyajima; Adikaari, AADT; Henley, SJ; Shannon, JM; Silva, SRP

    2008-01-01

    Amorphous carbon films containing no hydrogen were irradiated with a pulsed UV laser in vacuum. Raman spectroscopy indicates an increase in the quantity of sp(2) clustering with the highest laser energy density and a commensurate reduction in resistivity. The reduction of resistivity is explained to be associated with thermally induced graphitization of amorphous carbon films. The high field transport is consistent with a Poole-Frenkel type transport mechanism via neutral trapping centers rel...

  4. Plasma polymer films of tetravinylsilane modified by UV irradiation

    Čech, V.; Lichovníková, S.; Trivedi, R.; Peřina, Vratislav; Zemek, Josef; Mikulík, P.; Caha, O.

    2010-01-01

    Roč. 205, Suppl. 1 (2010), S177-S181. ISSN 0257-8972. [Asian-European International Conference on Plasma Surface Engineering/7./ - AEPSE 2009. Busan, 20.09.2009-25.09.2009] Institutional research plan: CEZ:AV0Z10100521; CEZ:AV0Z10480505 Keywords : thin film * PECVD * tetravinylsilane * UV irradiation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.135, year: 2010

  5. Hydrogel coating of RVNRL film by UV irradiation

    The surface properties of RVNRL film coated with UV curable formulations have been investigated in order to develop suitable UV curable formulation which give the RVNRL surface reduced tackiness and increased hydrophilicity. In this context several type of monomers polymers and photoinitiators have been used with varying degrees of success. The tackiness, hardness, contact angle and water absorption of the coated RVNRL film surface were evaluated. Attempts have also been made to enhance the adhesion between the coated layer and the RVNRL film. It was found that the RVNRL film in wet gel stage coated with formulation F2 render relatively good optimum properties with respect to cure speed, tackiness, hardness and adhesion. Studies on surface topography revealed that the RVNRL surface was made rough upon coating by UV irradiation. (Author)

  6. Thermal Degradation and Damping Characteristic of UV Irradiated Biopolymer

    Anika Zafiah M. Rus

    2015-01-01

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

  7. Effects of UV-C irradiation on development of goldfish embryos

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

  8. A Rapid Synthesis of Oriented Palladium Nanoparticles by UV Irradiation

    Navaladian S

    2008-01-01

    Full Text Available Abstract Palladium nanoparticles of average size around 8 nm have been synthesized rapidly by UV irradiation of mixture of palladium chloride and potassium oxalate solutions. A rod-shaped palladium oxalate complex has been observed as an intermediate. In the absence of potassium oxalate, no Pd nanoparticles have been observed. The synthesized Pd nanoparticles have been characterized by powder X-ray diffraction (XRD, transmission electron microscopy (TEM, selective area electron diffraction and energy dispersive analysis by X-rays (EDAX analyses. XRD analysis indicates the preferential orientation of catalytically active {111} planes in Pd nanoparticles. A plausible mechanism has been proposed for the formation of anisotropic Pd nanoparticles.

  9. Solar cycle variation in UV solar spectral irradiance

    Leng Yeo, Kok; Krivova, Natalie; Solanki, Sami K.

    2015-08-01

    Solar spectral irradiance, SSI, in the UV has been measured from space, almost without interruption, since 1978. This is accompanied by the development of models aimed at reconstructing SSI by relating its variability to solar magnetic activity. The various satellite records and model reconstructions differ significantly in terms of the variation over the solar cycle, with the consequence that their application to climate models yield qualitatively different results. Here, we highlight the key discrepancies between available records and reconstructions, and discuss the possible underlying causes.

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

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

    2008-11-01

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

  11. [Biodegradation under UV irradiation and microbial community changes].

    Yan, Ning; Xia, Si-Qing; Zhu, Jun; Zhang, Yong-Ming

    2011-10-01

    Photolytic circulating-bed biofilm reactor (PCBBR) and internal loop photolytic-biological reactor (ILPBR) were respectively used for degradation of phenol, 2, 4, 6-trichlorophenol (TCP) and sulfamethoxazole (SMX). Experimental results indicated that the rates of phenol, TCP and SMX removal by coupled photolysis with biodegradation (P&B) reached at 0.65, 0.11 and 0.17 mg x (L x min)(-1), which was clearly higher than that by photolysis alone (P), biodegradation alone (B), except phenol removal rate by B,which was similar to the rates by P&B. The COD removal percentages of phenol and TCP were 99.5% and 72.1%, and TOC removal percentage of SMX was 57.3, which all were higher that by P and B. The biofilms under UV irradiation were taken as samples for molecular biological analysis to get the significant results that microbial communities in biofilms took great change compared with that without UV irradiation, but they still kept bioactivity degrading organic pollutants. That is significant results for technological innovation on recalcitrant organic wastewater treatment. PMID:22279924

  12. Photooxidation of tetrahydrobiopterin under UV irradiation: possible pathways and mechanisms.

    Buglak, Andrey A; Telegina, Taisiya A; Lyudnikova, Tamara A; Vechtomova, Yulia L; Kritsky, Mikhail S

    2014-01-01

    Tetrahydrobiopterin (H4 Bip) is a cofactor for several key enzymes, including NO synthases and aromatic amino acid hydroxylases (AAHs). Normal functioning of the H4 Bip regeneration cycle is extremely important for the work of AAHs. Oxidized pterins may accumulate if the H4 Bip regeneration cycle is disrupted or if H4 Bip autoxidation occurs. These oxidized pterins can photosensitize the production of singlet molecular oxygen (1)O2 and thus cause oxidative stress. In this context, we studied the photooxidation of H4 Bip in phosphate buffer at pH 7.2. We found that UV irradiation of H4 Bip affected its oxidation rate (quantum yield Φ300 = (2.7 ± 0.4) × 10(-3)). The effect of UV irradiation at λ = 350 nm on H4 Bip oxidation was stronger, especially in the presence of biopterin (Bip) (Φ350 = (9.7 ± 1.5) × 10(-3)). We showed that the rate of H4 Bip oxidation linearly depends on Bip concentration. Experiments with KI, a selective quencher of triplet pterins at micromolar concentrations, demonstrated that the oxidation is sensitized by the triplet state biopterin (3) Bip. Apparently, electron transfer sensitization (Type-I mechanism) is dominant. Energy transfer (Type-II mechanism) and singlet oxygen generation play only a secondary role. The mechanisms of H4 Bip photooxidation and their biological meaning are discussed. PMID:24773158

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

    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. PMID:27004524

  14. Nanoparticle production by UV irradiation of combustion generated soot particles

    Laser ablation of surfaces normally produce high temperature plasmas that are difficult to control. By irradiating small particles in the gas phase, we can better control the size and concentration of the resulting particles when different materials are photofragmented. Here, we irradiate soot with 193 nm light from an ArF excimer laser. Irradiating the original agglomerated particles at fluences ranging from 0.07 to 0.26 J/cm2 with repetition rates of 20 and 100 Hz produces a large number of small, unagglomerated particles, and a smaller number of spherical agglomerated particles. Mean particle diameters from 20 to 50 nm are produced from soot originally having a mean electric mobility diameter of 265 nm. We use a non-dimensional parameter, called the photon-atom ratio (PAR), to aid in understanding the photofragmentation process. This parameter is the ratio of the number of photons striking the soot particles to the number of the carbon atoms contained in the soot particles, and is a better metric than the laser fluence for analyzing laser-particle interactions. These results suggest that UV photofragmentation can be effective in controlling particle size and morphology, and can be a useful diagnostic for studying elements of the laser ablation process

  15. Nanoparticle production by UV irradiation of combustion generated soot particles

    Laser ablation of surfaces normally produce high temperature plasmas that are difficult to control. By irradiating small particles in the gas phase, we can better control the size and concentration of the resulting particles when different materials are photofragmented. Here, we irradiate soot with 193 nm light from an ArF excimer laser. Irradiating the original agglomerated particles at fluences ranging from 0.07 to 0.26 J/cm2 with repetition rates of 20 and 100 Hz produces a large number of small, unagglomerated particles, and a smaller number of spherical agglomerated particles. Mean particle diameters from 20 to 50 nm are produced from soot originally having a mean electric mobility diameter of 265nm. We use a non-dimensional parameter, called the photon/atom ratio (PAR), to aid in understanding the photofragmentation process. This parameter is the ratio of the number of photons striking the soot particles to the number of the carbon atoms contained in the soot particles, and is a better metric than the laser fluence for analyzing laser-particle interactions. These results suggest that UV photofragmentation can be effective in controlling particle size and morphology, and can be a useful diagnostic for studying elements of the laser ablation process

  16. Comparison of N-nitrosodiethylamine degradation in water by UV irradiation and UV/O3: Efficiency, product and mechanism

    N-Nitrosodiethylamine (NDEA) is a member of nitrosamines, which is strong carcinogenic. In order to explore an effective treatment method for NDEA removal from water, sole UV irradiation and UV/O3 were carried out in this study. The removal efficiency, degradation products and pathways were compared between those two processes. Results showed that NDEA removal efficiency achieved 99% within 15 min by both UV and UV/O3. Degradation reaction well followed pseudo-first-order kinetics. Water pH had different effect on NDEA degradation in those two processes. Acidic and neutral conditions were good for NDEA degradation by sole UV irradiation. However, NDEA underwent rapid degradation under various pH conditions in the UV/O3 process. Though the ozone introduction in the UV/O3 process had little effect on NDEA degradation efficiency, it had significant effect on its degradation products and pathways. Methylamine, dimethylamine, ethylamine and diethylamine were observed as aliphatic amine products of NDEA degradation in both two processes. They were assumed to arise due to N-N bond fission under UV irradiation, or due to the reaction of NDEA and hydroxyl radicals in the UV/O3 process.

  17. Efficiency of UV-irradiated autotransfusion in treatment of calves' diseases

    Effect of UV-irradiated autotransfusion on content of cation proteins and myeloperoxidase in blood granulocytes of different age calves is studied. High efficiency of irradiated blood autotransfusion in case of dyspepsia and bronchopneumonia of calves is demonstrated

  18. UV-induced self-aggregation of E. coli after low and medium pressure ultraviolet irradiation.

    Kollu, Kerim; Örmeci, Banu

    2015-07-01

    Presence of aggregated bacteria has been shown to decrease the efficacy of ultraviolet (UV) disinfection and there is some indication that UV irradiation may promote aggregation of bacteria among themselves. This study aims to provide an in-depth understanding of the effect of UV light on inducing self-aggregation of Escherichia coli bacteria by using microscopy and particle counter analysis techniques. The bacteria were observed and quantified before and after UV irradiation by employing size and concentration parameters. Four doses of low-pressure (LP) UV irradiation, 20, 40, 60 and 80 mJ/cm(2), and two doses of medium-pressure (MP) UV irradiation, 40 and 80 mJ/cm(2), were tested. At all LP UV doses tested, a significant increase in particle size was observed following UV exposure, indicating UV-induced self-aggregation. However, the magnitude of UV dose did not seem to have an impact. In the MP UV experiments, only a dose of 80 mJ/cm(2) had a significant impact on the formation of aggregates upon UV exposure. Changing the light intensity and exposure time to deliver the same LP UV dose resulted in different levels of aggregation. The results indicated that UV light intensity and wavelength may play a role in aggregation of bacteria. PMID:26002538

  19. Use of UV irradiation to reduce false positivity in polymerase chain reaction

    UV irradiation provides a simple and efficient way to minimize contamination or false positivity which often occurs in laboratories performing routine PCR tests. Here, we characterize several parameters of the effect of UV irradiation on DNA template, primers, deoxynucleoside triphosphate and Taq polymerase. UV irradiation of DNA results in the formation of pyrimidine dimers and thus prevents them from being effective templates in subsequent PCR. Reduction of the HIV DNA templates in polypropylene microcentrifuge tubes by more than 1000-fold can be achieved by UV irradiation. The sensitivity of the primers is sequence- and concentration-dependent. Oligonucleotides with neighboring thymine bases are more susceptible to UV than those without. Taq polymerase is highly UV sensitive, whereas deoxynucleotide triphosphate is relatively UV resistant

  20. The migration of human lens epithelial cells induced by UV-irradiation in vitro

    Jin Yao; Guoxing Yuan; Yuan Liu; Yi Shen; Qin Jiang

    2008-01-01

    Objective: Ultraviolet (UV) radiation is one of the important cataract risk factors. However, the pathogenesis is still poorly understood.The migration of human lens epithelial cells(HLECs) plays a crucial role in the remodeling of lens capsule and cataract formation. The purpose of this study is to investigate the mechanism of UV inducing cataractogenesis. Methods:The toxicity of UV-irradiation on HLECs was assessed by Methyl thiazolyl tetrazolium(MTT) assay. The activity of matrix metalloproteinase-2(MMP-2) was observed by Gelatin zymography. The migration of HLECs was examined by Cell Track Motility. Results:UV-irradiation does great harm to HLECs, and may induce apoptosis in the cells when UV higher than 15 mj/cm2. UV significantly increased MMP-2 activity in a timedependent manner. In addition, the irradiation could induce the migration of HLECs. Conclusion:UV-irradiation could induce the migration of HLECs by increasing the activity of MMP-2.

  1. Surface properties of UV irradiated PC–TiO2 nanocomposite film

    Highlights: • Production of PC–TiO2 nanocomposite films. • Fully characterization of PC–TiO2 nanocomposite films. • Influence of UV irradiation on surface properties and hardness of PC–TiO2 nanocomposite film. - Abstract: In this work, polycarbonate–TiO2 nanocomposite films were prepared with two different percentages. The structure of samples were studied by X-ray diffraction. Thermal stability of the nanocomposites was studied by thermogravimetric analysis (TGA). The polycarbonate and polycarbonate–TiO2 nanocomposite films were exposed by UV light at different irradiation times. The effects of UV irradiation on the surface properties of samples have been studied by different characterization techniques, viz. scanning electron microscopy (SEM), FTIR spectroscopy, X-ray photoelectron spectroscopy (XPS), contact angle measurement and Vickers microhardness tester. Hydrophilicity and surface energy of UV treated samples varied depending on UV irradiation time. TGA curves showed that nanocomposite films have higher resistance to thermal degradation compared to polycarbonate. XPS analysis shows that surface of samples become more oxidized due to UV irradiation. For nanocomposite film, the smallest contact angle was observed in association with the longest UV irradiation time. The contact angle significantly decreased from 90° to 12° after 15 h of UV irradiation. It is observed that the hardness of the nanocomposite films increases after UV irradiation

  2. UV solar irradiance in observations and the NRLSSI and SATIRE-S models

    Yeo, K L; Krivova, N A; Solanki, S K; Unruh, Y C; Morrill, J

    2015-01-01

    Total solar irradiance and UV spectral solar irradiance have been monitored since 1978 through a succession of space missions. This is accompanied by the development of models aimed at replicating solar irradiance by relating the variability to solar magnetic activity. The NRLSSI and SATIRE-S models provide the most comprehensive reconstructions of total and spectral solar irradiance over the period of satellite observation currently available. There is persistent controversy between the various measurements and models in terms of the wavelength dependence of the variation over the solar cycle, with repercussions on our understanding of the influence of UV solar irradiance variability on the stratosphere. We review the measurement and modelling of UV solar irradiance variability over the period of satellite observation. The SATIRE-S reconstruction is consistent with spectral solar irradiance observations where they are reliable. It is also supported by an independent, empirical reconstruction of UV spectral s...

  3. Serum amyloid A1 secreted from UV-irradiated keratinocytes induces matrix metalloproteinase-1 in fibroblasts through toll-like receptor 4.

    Han, Sangbum; Jin, Seon-Pil; Oh, Jang-Hee; Seo, Eun-Young; Park, Chi-Hyun; Yoon, Hyun-Sun; Lee, Dong Hun; Chung, Jin Ho

    2016-07-01

    Ultraviolet (UV) irradiation on skin triggers photoageing-related phenotypes such as formation of wrinkles. UV ray upregulates matrix metalloproteinase-1 (MMP-1), which in turn degrades extracellular matrix proteins, mostly collagens. Serum amyloid A1 (SAA1) is an acute-phase protein of which plasma concentration increases in response to inflammation. Although the expression of SAA1 in the skin was reported, its function in the skin is yet to be studied. In this research, we found that the expression of SAA1 was increased in acute UV-irradiated buttock skin and photoaged forearm skin in vivo. UV irradiation also increased SAA1 in normal human epidermal keratinocytes (NHEK), and treatment of recombinant human SAA1 (rhSAA1) induced MMP-1 in normal human dermal fibroblasts (NHDF) but not in NHEK. Next, we demonstrated that NHDF treated with UV-irradiated keratinocyte-conditioned media showed the increased MMP-1 expression; however, this increase of MMP-1 in NHDF was inhibited by knockdown of SAA1 in NHEK. In addition, knockdown of Toll-like receptor 4 (TLR4) inhibited rhSAA1-induced MMP-1 expression in NHDF. Taken together, our data showed that UV-induced SAA1 production in NHEK, and this secreted SAA1 induced MMP-1 expression in NHDF in a paracrine manner through TLR4 signalling pathway. Therefore, our results suggest that SAA1 can be a potential mediator for UV-induced MMP-1 expression in human skin. PMID:26900010

  4. Photopatch and UV-irradiated patch testing in photosensitive dermatitis

    Reena Rai

    2016-01-01

    Full Text Available Background: The photopatch test is used to detect photoallergic reactions to various antigens such as sunscreens and drugs. Photosensitive dermatitis can be caused due to antigens like parthenium, fragrances, rubbers and metals. The photopatch test does not contain these antigens. Therefore, the Indian Standard Series (ISS along with the Standard photopatch series from Chemotechnique Diagnostics, Sweden was used to detect light induced antigens. Aim: To detect light induced antigens in patients with photosensitive dermatitis. Methods: This study was done in a descriptive, observer blinded manner. Photopatch test and ISS were applied in duplicate on the patient's back by the standard method. After 24 hours, readings were recorded according to ICDRG criteria. One side was closed and other side irradiated with 14 J/cm2 of UVA and a second set of readings were recorded after 48 hrs. Result: The highest positivity was obtained with parthenium, with 18 out of 35 (51% patients showing a positive patch test reaction with both photoallergic contact dermatitis and photoaggravation. Four patients (11% showed positive patch test reaction suggestive of contact dermatitis to potassium dichromate and fragrance mix. Six patients had contact dermatitis to numerous antigens such as nickel, cobalt, chinoform and para-phenylenediamine. None of these patients showed photoaggravation on patch testing. Conclusion: Parthenium was found to cause photoallergy, contact dermatitis with photoaggravation and contact allergy. Hence, photopatch test and UV irradiated patch test can be an important tool to detect light induced antigens in patients with photosensitive dermatitis.

  5. Positron annihilation in silica aerogel UV-irradiated at low temperature

    Positron lifetime spectra for the silica aerogel heat-treated at various temperatures (373 K-673 K) have been measured following UV-irradiation at 30 K. It has been observed that positronium lifetime in the UV-irradiated silica aerogel depends on the heat-treatment temperature. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Induction of UV photoproducts and DNA damage by solar simulator UV irradiation

    The recent increased incidence of skin cancer and the depletion of the ozone layer has increased interest in the ultraviolet (UV) component of natural sunlight and its role in the induction of skin cancer. Previous research on UV radiation has concentrated on UVC (254nm) but, as only UVB and UVA are present in natural sunlight, its relevance is unknown. We have investigated the induction of two forms of direct DNA damage - the pyrimidine dimer and the (6-4) photoproduct - in human DNA repair deficient XP-G (Xeroderma pigmentosum group G) lymphoblastoid cells following exposure to simulated sunlight. As exposure to natural sunlight is highly variable, a solar simulator lamp was used which is known to mimic natural sunlight at midday in Central Europe. Cells were irradiated on ice to minimise DNA repair and the relative induction of pyrimidine dimers and (6-4) photoproducts was measured using specific monoclonal antibodies and a computer assisted image analysis system. A time dependent increase in both cyclobutane dimer and (6-4) photoproduct antibody binding sites was seen. The increases in pyrimidine dimer and (6-4) photoproduct antibody binding sites differed to that reported with natural sunlight in the UK but was similar to that seen with a similar solar simulator lamp

  7. Effect of UV Irradiation on Interactions of α-Lipoic Acid with Free Radicals

    Paweł Ramos; Piotr Pepliński; Barbara Pilawa

    2013-01-01

    Changes of antioxidant properties of α-lipoic acid (LA) after UV irradiation were studied. LA is the typical drug used in diabetic neuropathy. Quenching of free radicals is an important factor of therapy by using this substance. α-Lipoic acid is exposed to UV irradiation during the storage. The aim of our studies was to examine the effect of UV irradiation on the interactions of LA with free radicals. The α-lipoic acid was irradiated by UVA 315–400 nm light during 10 to 110 minutes by interva...

  8. ETCHING OF WRINKLED GRAPHENE OXIDE FILMS IN NOBLE GAS ATMOSPHERE UNDER UV IRRADIATION

    ALEKSENSKII A.E.; VUL S.P.; DIDEIKIN A.T.; Sakharov, V. I.; SERENKOV I.T.; RABCHINSKII M.K.; AFROSIMOV V.V.

    2016-01-01

    We have studied the process of UV reduction of wrinkled grahpene oxide films, deposited on silicon substrate from ethanol suspension. In order to avoid destruction of graphene oxide via ozone formation from ambient air, samples were protected by argon atmosphere during UV irradiation. Using the analysis of back scattering spectra for medium energy ions, we have found that the UV irradiation mediated reduction process produced significantly decreased carbon content on the substrate surface. Th...

  9. γ-ray-enhanced reactivation of UV-irradiated adenovirus in normal human fibroblasts

    An enhanced reactivation of UV-irradiated adenovirus type 2 (Ad 2) was detected following irradiation of the host cells with γ-rays prior to infection. Non-irradiated and γ-irradiated normal human fibroblasts were infected immediately after irradiation with either non-irradiated or UV-irradiated Ad 2. At 48 h after infection, cultures were examined by indirect immunofluorescence to determine the number of cells in which the viral function of viral structural antigen (Vag) was expressed. Pre-irradiation of cells with 1 krad resulted in a 2-3 fold increase in the survival of this viral function following different UV doses to the virus up to 1.75x103 J/m2. For a fixed UV dose of 1.0x103 J/m2 to the virus this enhancement increased with preirradiation dose to the Vag expression at various times after infection indicates that pre-irradiation of the cells with γ-rays prior to infection with UV-irradiated virus leads to an earlier onset and/or increased rate of Vag synthesis. This enhancement of Vag production from a UV-damaged template may result from an inducible DNA-repair mechanism in human fibroblasts which may or may not be error-prone. (Auth.)

  10. Standard UV-B irradiation of platelets concentrates to prevent from PT-GVHD for alloimmunization

    Takahashi, Takayoshi [Toranomon Hospital, Tokyo (Japan); Nagahashi, Hisakata; Takenouchi, Kogi; Tayama, Tatsuya; Tadokoro, Kenji; Juji, Takeo

    1994-11-01

    We tried to make an appropriate standard condition for UV-B irradiation of platelets concentrates (PC), which is useful for prophylaxis against post-transfusion graft versus host disease (PT-GVHD) as well as prevention against alloimmunization. Agitation of PC bags during UV-B irradiation is necessary to irradiate evenly cells in the bag, because a lot of UV-B ray should be absorbed by bag membrane and plasma. Amounts of UV-B that each lymphocyte or platelet would actually receive on an average (UVavg) was calculated by the equation as below. UV{sup *}avg=K{sub 1} x (K{sub 2}{sup L} - 1) x UV/(log{sub e}K{sub 2} x L), K{sub 1} and K{sub 2} are permeability index of bag membrane and that in plasma, respectively; while L and UV stands for depth of PC bag and emitting dose of UV-B, respectively. We irradiated PC bags with UV-B in a dose of 541-13,525 J/m{sup 2} of UV{sup *}avg, and examined lymphocytes in the bags about the responder and stimulator activities in mixed lymphocytes culture (MLR), as well as platelet function in the bags. Irradiation more than 5,000 J/m{sup 2} of UV{sup *}avg is needed to suppress responder and stimulator activities, and platelet function is maintained up to 13,525 J/m{sup 2} of UV{sup *}avg. In conclusion, UV-irradiation in a range of 6,000-13,000 J/m{sup 2} of UV{sup *}avg is considered appropriate to prevent from RT-GVHD or alloimmunization. (author).

  11. Isoflavones protect mouse embryonic stem cells to UV-irradiation injury

    Ultraviolet (UV) light is a strong apoptotic trigger that induces caspase-dependent biochemical changes in cells. Previously we showed that UV irradiation can activate caspase-3 and the subsequent apoptotic biochemical changes in human epidermoid carcinoma A431 cells. In this report we demonstrate that isoflavones (i.e., genistein and daidzein), natural compounds found in soy products, can prevent UV irradiation-induced apoptotic changes, including DNA fragmentation, JNK (c-Jun N-terminal kinase) activation, mitochondrial release of cytochrome c, caspase-3 activation, and cleavage of poly-(ADP-ribose) polymerase (PARP) in embryonic stem cells, Flow cytometric analysis using the cell permeable dye 2',7' -dichlorofluorescin diacetate (DCF-DA) as an indicator of reactive oxygen species (ROS) generation revealed that increase in intracellular oxidative stress caused by UV irradiation, implicating that oxidative stress plays an important role in mediating the apoptotic effect of UV irradiation. Importantly, the UV irradiation-induced oxidative stress in stem cells could be significantly attenuated by isoflavones, suggesting that impairment of ROS formation during UV irradiation is responsible for the anti-apoptotic effect of isoflavones. Collectively, our results demonstrate the involvement of oxidative stress in the UV irradiation-induced apoptotic biochemical changes and show that isoflavones are potent inhibitors for this process. (authors)

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

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

  13. The induction and repair of DNA damage and its influence on cell death in primary human fibroblasts exposed to UV-A or UV-C irradiation

    Irradiation with UV-A of normal human fibroblasts in phosphate-buffered saline induced cell death, measured as lack of colony-forming ability. After UV-A irradiation, single-strand breaks (alkali-labile bonds) could be detected in DNA; these lesions were rapidly repaired. Excision repair, monitored as unscheduled DNA synthesis, was induced strongly by irradiation with UV-C, but could not be detected after UV-A irradiation. The results indicate that lethality by UV-A wavelengths > 330 nm is caused by lesions other than single-strand breaks (alkali-labile bonds) and pyrimidine dimers. (Auth.)

  14. UV Irradiation Chlorine Dioxide Photocatalytic Oxidation of Simulated Fuchsine Wastewater by UV-Vis and Online FTIR Spectrophotometric Method

    Jie Liu; Chunlei Huai; Na Li; Xiaomei Wang; Laishun Shi

    2012-01-01

    The photocatalyst TiO2/SiO2 was prepared and used for chlorine dioxide photocatalytic oxidation of simulated fuchsine wastewater under UV irradiation. The removal efficiency of fuchsine treated by photocatalytic oxidation process is higher than that of chemical oxidation process. By using UV-Vis and online FTIR analysis technique, the intermediates during the degradation process were obtained. The benzene ring in fuchsine was degraded into quinone and carboxylic acid and finally changed into ...

  15. Changes of selected secondary metabolites in potatoes and buckwheat caused by UV, gamma- and microwave irradiation

    Changes of total polyphenols, phenolcarboxylic acids and ascorbic acid in potato tubers cv. Kordoba and Rosella and three buckwheat samples (seeds, seedlings and plants: F. esculentum, cv. Pyra and Emka and tartarian buckwheat F. tataricum) induced by UV-C irradiation, gamma-irradiation and microwave irradiation were investigated

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

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

  17. Proteolytic activities in yeast after UV irradiation. Pt. 1

    Specific proteolytic activities are known to be induced in Escherichia coli following irradiation. Consequently it seemed of interest to investigate whether variations in proteinase activities occur in yeast. Among the five most well known proteinases of Saccharomyces cerevisiae, we have found that proteinase B activity increases up to three times in wild-type RAD+ yeast cells after a dose of 50 Jm-2 of 254 nm ultraviolet light (40% survival). Carboxypeptidase Y and aminopeptidase I (leucin aminopeptidase) activities were only moderately increased. Proteinase A activity was only slightly enhanced, while aminopeptidase II (lysin aminopeptidase) was unaffected in both RAD+ strains studied. The observed post UV-increase in proteinase B activity was inhibited by cycloheximide and was dose dependent. Increases in proteinase B levels were independent of the activation method used to destroy the proteinase B-inhibitor complex present in the crude yeast extracts. A standard method for comparison of the postirradiation levels among different proteinases, strains and methods of activation is presented. (orig.)

  18. Dyeing of UV irradiated cotton and polyester fabrics with multifunctional reactive and disperse dyes

    Ijaz Ahmad Bhatti

    2016-03-01

    Full Text Available The dyeing behaviour of UV irradiated cotton and polyester fabrics using multifunctional reactive and disperse dyes has been investigated. The plain, woven, mercerized, bleached, cotton and polyester fabrics were exposed to UV radiation (180 w, 254 nm for 30, 60, 90 and 120 min. Dyeing was performed using irradiated fabric with a dye solution of un-irradiated reactive and disperse/azo dyes. The dyeing parameters such as, temperature, time, pH and salt concentration have been optimized. The colour strength values of dyed fabrics were evaluated by comparing irradiated and un-irradiated cotton and polyester fabrics in CIE Lab systems using spectra flash SF600. Finally ISO standard methods were employed to observe the effect of UV radiation on fastness properties. It was found that UV radiation has a potential to improve the colour strength values of cotton and polyester fabrics by using reactive and disperse dyes.

  19. UV spectral irradiance monitoring during the 1988 and 1989 Antarctic ozone holes

    Booth, C.R.; Lucas, T.B.; Morrow, J.H.; Yeh, J. (Biospherical Instruments, Inc., San Diego, CA (United States))

    1990-01-09

    UV spectral irradiance incident at the United States bases at McMurdo, Palmer, and the South Pole, in Antarctica, and at an Argentina Laboratory in Ushuaia is being routinely monitored by the NSF UV Spectroradiometer Network. Coverage includes the 1988 and 1989 ozone hole seasons and show marked differences between these two years. Many different methods of assessing UV irradiance or exposure are found in the literature. The degree of contrast between the 1988 and 1989 seasons varies widely depending upon the UV assessment method chosen. Data will be presented describing how different assessment methods present this time series.

  20. The relationship between pyrimidine dimers and replicating DNA in UV-irradiated human fibroblasts

    The relationship between pyrimidine dimers (measured as endonuclease-sensitive sites) and newly-synthesized DNA was examined in UV-irradiated normal and XP variant human fibroblasts. Following irradiation of normal cells, the frequency of pyrimidine dimer sites in sections of DNA which had been synthesized immediately before the UV-irradiation was similar to that in the bulk DNA. The frequency of pyrimidine dimer sites in the parental strands of replicating DNA in irradiated normal cells was similar to that in the bulk DNA. In UV-irradiated XP variant cells, the size of DNA synthesized in the presence of caffeine immediately after irradiation accurately corresponded with the average interdimer distance in the parental DNA. This suggested that in this experimental situation each pyrimidine dimer gives rise to a discontinuity or a termination site in the daughter strand. (author)

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

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

  2. Synthesis and Characterization of Silver/Clay/Chitosan Bionanocomposites by UV-Irradiation Method

    Mansor B. Ahmad

    2009-01-01

    Full Text Available Problem statement: Silver/Montmorillonite/Chitosan Bionanocomposites (Ag/MMT/Cts BNCs have been synthesized by UV-irradiation reduction method in the absence of any reducing agent or heat treatment which is used to antibacterial application and medical devices. Approach: MMT, Chitosan and AgNO3 were used as a solid support, stabilizer and silver precursor, respectively. The properties of Ag/MMT/Cts BNCs were studied as a function of UV-irradiation times. The crystalline structure, d-spacing of interlayer of MMT, the size distributions and surface plasmon resonance of synthesized silver nanoparticles (Ag-NPs were characterized using Powder X-Ray Diffraction (PXRD, Transmission Electron Microscopy (TEM and UV-vis spectroscopy. The functional groups of prepared BNCs were also determined by Fourier Transform Infrared (FT-IR. Results: The results obtained from UV-vis spectroscopy of synthesized Ag-NPs showed that the intensity of the maximum wavelength of the plasmon peaks were increased with the increasing in the UV-irradiation times. Results from UV-visible spectroscopy and Transmission Electron Microscopy (TEM microphotographs show that particles size of Ag-NPs decrease with the increase of UV-irradiation time. Conclusion: UV-irradiation disintegrated the Ag-NPs into smaller size until a relatively stable size and size distribution were achieved. Ag/MMT/Cts BNCs could be suitable to antimicrobial applications and medical devices.

  3. Effects of UV irradiation on a living skin equivalent

    The Living Skin Equivalent is an organotypic coculture composed of human dermal fibroblasts interspersed in a collagen-containing matrix and overlaid with human keratinocytes forming a stratified epidermis. The LSE has a dry, air-exposed epidermal surface suitable for the application of oils, creams and emulsions. The protective effects of an 8% homosylate standard and of five UV-A sunscreens, topically applied to the LSE, were determined and compared with their reported protection factors in human skin. Morphological changes and the release of proinflammatory mediators (interleukin-1-''alpha, tumor necrosis factor-α and prostaglandin E2) implicated in UV-induced erythema were also demonstrated in the LSE exposed to UV-A or UV-B. The data suggest that the LSE can be used for studying the effects of UV radiation on skin and may have utility for assessing the efficacy of certain sunscreens against UV-B and UV-A. (Author)

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

    Bao, Y

    2000-04-01

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

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

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

  6. Systemic suppression of delayed-type hypersensitivity by supernatants from UV-irradiated keratinocytes

    Rivas, J.M.; Ullrich, S.E. (Univ. of Texas, Houston (United States))

    1992-12-15

    Exposing murine keratinocyte cultures to UV radiation causes the release of a suppressive cytokine that mimics the immunosuppressive effects of total-body UV exposure. Injecting supernatants from UV-irradiated keratinocyte cultures into mice inhibits their ability to generate a delayed-type hypersensitivity reaction against allogeneic histocompatibility Ag, and spleen cells from mice injected with supernatant do not respond to alloantigen in the in vitro MLR. A unique feature of the immunosuppression induced by either total-body UV-exposure or injecting the suppressive cytokine from UV-irradiated keratinocytes is the selectivity of suppression. Although cellular immune reactions such as delayed-type hypersensitivity are suppressed antibody production is unaffected. Because the selective nature to the UV-induced immunosuppression is similar to the biologic activity of IL-10, the authors examined the hypothesis that UV exposure of keratinocytes causes the release of IL-10. Keratinocyte monolayers were exposed to UV radiation and at specific times after exposure mRNA was isolated or the culture supernatant from the cells was collected. These data indicate that activated keratinocytes are capable of secreting IL-10 and suggest that the release of IL-10 by UV-irradiated keratinocytes plays an essential role in the induction of systemic immunosuppression after total-body UV exposure. 44 refs., 3 figs., 2 tabs.

  7. Chlorophyll bleaching by UV-irradiation in vitro and in situ: Absorption and fluorescence studies

    Chlorophyll bleaching by UV-irradiation has been studied by absorbance and fluorescence spectroscopy in extracts containing mixtures of photosynthetic pigments, in acetone and n-hexane solutions, and in aqueous thylakoid suspensions. Chlorophyll undergoes destruction (bleaching) accompanied by fluorescent transient formation obeying first-order kinetics. The bleaching is governed by UV-photon energy input, as well as by different chlorophyll molecular organizations in solvents of different polarities (in vitro), and in thylakoids (in situ). UV-C-induced bleaching of chlorophylls in thylakoids is probably caused by different mechanisms compared to UV-A- and UV-B-induced bleaching

  8. Assays of residual antibiotics after treatment of {gamma}-ray and UV irradiation

    Shin, Ji Hye; Nam, Ji Hyun; Lee, Dong Hun [Chungbuk National University, Cheongju (Korea, Republic of); Yu, Seung Ho; Lee, Myun Joo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2010-03-15

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

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

    The photochemical decomposition of perfluorooctanoic acid (PFOA) in aqueous periodate (IO4-) 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 IO4- significantly increased the rate of decomposition and defluorination of PFOA irradiated with UV light whereas it decreased both processes under VUV irradiation. Reactive radical (IO3·) generated by photolysis of IO4- initiated the oxidation of PFOA in UV process. Aquated electrons (eaq-), generated from water homolysis, scavenged IO4- 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.

  10. Enhanced biosynthesis of quercetin occurs as A photoprotective measure in Lycopersicon esculentum mill. under Acute UV-B exposure

    Abhilasha Shourie

    2014-06-01

    Full Text Available Lycopersicon esculentum respond to UV-B by enhanced synthesis of flavonoid quercetin, a strong antioxidant that helps the plants to well acclimatize to UV-B stress. Three weeks old plants of L. esculentum were subjected to acute UV-B irradiation for 20, 40 and 60 minutes daily until 28 days and analyzed for the morphological and biochemical changes. UV-B exposure for 40 and 60 minutes considerably affected the growth and biomass of L. esculentum. The leaves were deformed, developed chlorosis and abscised early as compared to the unexposed plants. Biomass declined by 35% and total chlorophyll decreased by 24.7% due to disintegration of chloroplasts. Enhancement was seen in the content of carotenoids, anthocyanins and total flavonoids by 15, 33.3 and 22.8%, respectively, which was attributed to the photoprotective role of these compounds as potential quenchers of excess excitation energy. Quercetin content decreased on UV-B exposure to 20 and 40 min, and thereafter increased significantly by 5.19% on 60 min of exposure. This pattern probably indicated that the over-expression of genes involved in its biosynthesis such as phenylalanine ammonia lyase (PAL, chalcone synthase (CHS, flavanone 3-hydroxylase (F3H and dihydroflavonol 4-reductase (DFR occurred only after certain threshold exposure (60 min, which could be the strategy for developing tolerance against UV-B stress in L. esculentum.

  11. In vitro RNA synthesis with UV-irradiated phage lambda DNA

    Irradiation of phage lambda DNA with UV light at a dose of 10 Jm-2 leads to a 40% decrease in DNA template activity and at a dose of 100 Jm-2 - to its complete suppression. This is apparently due to the transcription-terminating effect mainly of pyrimidine dimers. Electrophoretic analysis of RNA shows that RNA chains, homogeneous on their molecular weight but shorter, are produced in vitro with 10 Jm-2 UV-irradiated DNA. (author)

  12. Cell cycle and DNA repair in UV-irradiated cells of mouse neuroblastoma

    A correlation has been shown between a reduced rate of movement of UV-irradiated neuroblastoma cells from G1 into S phase, an essential increase of cells in S phase while progressing through the cell cycle, and a defect in free DNA synthesis on a damaged template. These indices may reflect one and the same cell response to the UV light

  13. Homology and repair of UV-irradiated plasmid DNA in Haemophilus influenzae

    UV-irradiated plasmid pNov1 containing a cloned fragment of chromosomal DNA could be repaired by excision, but plasmid p2265 without homology to the chromosome could not. Establishment of pNov1 was more UV resistant in Rec- than in Rec+ cells. 19 references, 2 figures

  14. Survival of Spacecraft-Associated Microorganisms under Simulated Martian UV Irradiation

    Newcombe, David A.; Schuerger, Andrew C.; Benardini, James N.; Dickinson, Danielle; Tanner, Roger; Venkateswaran, Kasthuri

    2005-01-01

    Spore-forming microbes recovered from spacecraft surfaces and assembly facilities were exposed to simulated Martian UV irradiation. The effects of UVA (315 to 400 nm), UVA+B (280 to 400 nm), and the full UV spectrum (200 to 400 nm) on the survival of microorganisms were studied at UV intensities expected to strike the surfaces of Mars. Microbial species isolated from the surfaces of several spacecraft, including Mars Odyssey, X-2000 (avionics), and the International Space Station, and their a...

  15. Features of the Sterilization by VUV/UV Irradiation of Low-Pressure Discharge Plasma

    Tsiolko, Vyacheslav V.

    The review is devoted to peculiarities of sterilization of items by VUV/UV ­radiation of the discharge plasma both in case of the items immersed into the ­discharge plasma ("direct plasma" treatment), and in case of flowing afterglow plasma ("remote plasma" treatment). The issues of influence of such factors as UV irradiation spectrum, substrate temperature on the UV sterilization efficiency are also considered.

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

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

  17. Initial assessment of physiological response to UV-B irradiation using fluorescence measurements

    Fluorescence emissions obtained by excitation at 280 and 340 nm (280 EX 300-520 nm; 340EX 360-800 nm) were used to discriminate physiological change induced by ultraviolet B (UV-B) irradiation in two cucumber {Cucumis sativus L.) cultivars, Poinsett (UV-B sensitive) and Ashley (insensitive). Plants were grown in chambers with controlled spectral irradiation, including biologically effective UV-B irradiation (21 or 0.3kj m−2 d−1) provided for 5 days with photosynthetically active radiation (38 mol m−2d−1). Differentiating UV-B induced effects and cultivar differences proved more successful with a dimethyl sulfoxide (DMSO) leaf extract than with freshly excised, intact leaves. Poinsett exhibited significandy lower (P≤0.01) fluorescence for most wavelengths or spectral ratios, whether excited at 280 or 340 nm. The single dominant UV-A fluorescence peak observed in all 280EX emission spectra (330-350 nm) was shifted in DMSO from 340 to 350 nm in UV-B irradiated plants (with a significantly higher F350/F475 ratio, P≤0.001). This could indicate that UV-B irradiation altered the relative amounts of soluble protein invested in enzymes for photosynthesis (e.g., rubisco) versus UV-B protective compounds. In 340EX spectra, UV-B exposed plants also had higher blue/far-red ratios, possibly due to enhanced production of an antioxidant, blue fluorescing compound known to accumulate after UV-B induced degradation of rubisco. In DMSO, this ratio (F450/F730) was linearly related to the total carotenoid/Chl pigment ratio, with qualitatively different responses for the two cultivars. For 340EX spectra, UV-B effects were most successfully discriminated by the far-red peak, alone or included in a ratio with either red or blue fluorescence. UV-B irradiated plants exhibited a significantly lower (P<0.001) far-red peak in DMSO and lower far-red/red fluorescence ratios in both media, indicating loss of chlorophyll. The F730/F680 ratio for DMSO was log-linearly dependent on total

  18. An algorithm to evaluate solar irradiance and effective dose rates using spectral UV irradiance at four selected wavelengths

    The paper shows a semi-analytical method for environmental and dosimetric applications to evaluate, in clear sky conditions, the solar irradiance and the effective dose rates for some action spectra using only four spectral irradiance values at selected wavelengths in the UV-B and UV-A regions (305, 320, 340 and 380 nm). The method, named WL4UV, is based on the reconstruction of an approximated spectral irradiance that can be integrated, to obtain the solar irradiance, or convoluted with an action spectrum to obtain an effective dose rate. The parameters required in the algorithm are deduced from archived solar spectral irradiance data. This database contains measurements carried out by some Brewer spectrophotometers located in various geographical positions, at similar altitudes, with very different environmental characteristics: Rome (Italy), Ny Aalesund (Svalbard Islands (Norway)) and Ushuaia (Tierra del Fuego (Argentina)). To evaluate the precision of the method, a double test was performed with data not used in developing the model. Archived Brewer measurement data, in clear sky conditions, from Rome and from the National Science Foundation UV data set in San Diego (CA, USA) and Ushuaia, where SUV 100 spectro-radiometers operate, were drawn randomly. The comparison of measured and computed irradiance has a relative deviation of about ±2%. The effective dose rates for action spectra of Erythema, DNA and non-Melanoma skin cancer have a relative deviation of less than ∼20% for solar zenith angles <50 deg.. (authors)

  19. An algorithm to evaluate solar irradiance and effective dose rates using spectral UV irradiance at four selected wavelengths.

    Anav, A; Rafanelli, C; Di Menno, I; Di Menno, M

    2004-01-01

    The paper shows a semi-analytical method for environmental and dosimetric applications to evaluate, in clear sky conditions, the solar irradiance and the effective dose rates for some action spectra using only four spectral irradiance values at selected wavelengths in the UV-B and UV-A regions (305, 320, 340 and 380 nm). The method, named WL4UV, is based on the reconstruction of an approximated spectral irradiance that can be integrated, to obtain the solar irradiance, or convoluted with an action spectrum to obtain an effective dose rate. The parameters required in the algorithm are deduced from archived solar spectral irradiance data. This database contains measurements carried out by some Brewer spectrophotometers located in various geographical positions, at similar altitudes, with very different environmental characteristics: Rome (Italy), Ny Alesund (Svalbard Islands, Norway) and Ushuaia (Tierra del Fuego, Argentina). To evaluate the precision of the method, a double test was performed with data not used in developing the model. Archived Brewer measurement data, in clear sky conditions, from Rome and from the National Science Foundation UV data set in San Diego (CA, USA) and Ushuaia, where SUV 100 spectroradiometers operate, were drawn randomly. The comparison of measured and computed irradiance has a relative deviation of about +/-2%. The effective dose rates for action spectra of Erythema, DNA and non-Melanoma skin cancer have a relative deviation of less than approximately 20% for solar zenith angles <50 degrees . PMID:15266087

  20. Type C virus activation in nontransformed mouse cells by uv-irradiated herpes simplex virus

    Infection of nontransformed mouse cells with uv-irradiated herpes simplex virus (uv-HSV) resulted in the activation of an endogenous xenotropic (x-tropic) type C virus. Synthesis of type C virus persisted for only a few days, with most of the virus remaining cell associated. The levels of type C virus activated by uv-HSV varied depending on the multiplicity of infection (m.o.i.) and the uv dose. At low uv doses, where cell killing occurred, little or no type C virus synthesis was observed. Maximum levels of type C virus synthesis were observed with the minimum uv dose which eliminated cell killing by HSV. Synthesis of type C virus, albeit at lower levels, was still observed at uv doses beyond those required to prevent cell killing

  1. Technical relapsed testicular irradiation for acute lymphoblastic leukemia

    Testicular irradiation in children suffering from acute lymphoblastic leukemia presents difficulties in relation to daily positioning, dosimetry for dose homogenization of complex geometry and volume change during irradiation thereof. This can lead to significant deviations from the prescribed doses. In addition, the usual techniques often associated with unnecessary irradiation of pelvic simphysis, anus and perineum. This, in the case of pediatric patients, is of great importance, since doses in the vicinity of 20 Gy are associated with a deviation of bone growth, low testosterone levels around 24 Gy and high rates of generation of second tumors. To overcome these problems we propose a special restraint in prone and non-coplanar irradiation.

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

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

  3. In-situ investigation of graphene oxide under UV irradiation: Evolution of work function

    Jun Li

    2015-06-01

    Full Text Available Using in-situ Kelvin probe force microscopy (KPFM to measure surface potential, we investigated the time-dependent work function evolution of solution-processed graphene oxide (GO under ultraviolet (UV irradiation. We found that the work function of GO exposed in UV shows a notable decrease with increasing irradiation time, which is proposed to be attributed to the gradual disappearance of oxygen-containing functional groups in GO during the UV-induced reduction reaction process. Fourier transform infrared spectrum and Raman spectrum were used to confirm the reduction of GO under UV irradiation. Our study would give an insight into understanding the transformation of GO’s electronic structures during the reduction process.

  4. In-situ investigation of graphene oxide under UV irradiation: Evolution of work function

    Li, Jun; Qi, Xiang; Hao, Guolin; Ren, Long; Zhong, Jianxin, E-mail: jxzhong@xtu.edu.cn [Hunan Provincial Key Laboratory of Micro-Nano Energy Materials and Devices and School of Physics and Optoelectronics, Xiangtan University, Hunan 411105 (China); Laboratory for Quantum Engineering and Micro-Nano Energy Technology, Xiangtan University, Hunan 411105 (China)

    2015-06-15

    Using in-situ Kelvin probe force microscopy (KPFM) to measure surface potential, we investigated the time-dependent work function evolution of solution-processed graphene oxide (GO) under ultraviolet (UV) irradiation. We found that the work function of GO exposed in UV shows a notable decrease with increasing irradiation time, which is proposed to be attributed to the gradual disappearance of oxygen-containing functional groups in GO during the UV-induced reduction reaction process. Fourier transform infrared spectrum and Raman spectrum were used to confirm the reduction of GO under UV irradiation. Our study would give an insight into understanding the transformation of GO’s electronic structures during the reduction process.

  5. In-situ investigation of graphene oxide under UV irradiation: Evolution of work function

    Using in-situ Kelvin probe force microscopy (KPFM) to measure surface potential, we investigated the time-dependent work function evolution of solution-processed graphene oxide (GO) under ultraviolet (UV) irradiation. We found that the work function of GO exposed in UV shows a notable decrease with increasing irradiation time, which is proposed to be attributed to the gradual disappearance of oxygen-containing functional groups in GO during the UV-induced reduction reaction process. Fourier transform infrared spectrum and Raman spectrum were used to confirm the reduction of GO under UV irradiation. Our study would give an insight into understanding the transformation of GO’s electronic structures during the reduction process

  6. UV irradiance on the human skin: Effects of orientation and sky obstructions

    Koepke, Peter; Hess, Michael; Bretl, Sebastian; Seefeldner, Meinhard

    2009-03-01

    Modification factors (MF) are presented that allow the transfer of the UV index (UVI) into actual values of the UV irradiance on the human skin. The UVI is the general information on solar UV irradiance and valid for a horizontal surface under a sky without obstructions. The human skin, however, may be tilted and present in an environment whereby the sun or sky is obstructed, such as within a street canyon, or under a sunshade or trees. These MFs are nearly independent of atmospheric conditions and thus can be used to determine the UV irradiances that are vital for sun burn, skin cancer, and vitamin D production, from the readily available actual UVI, which vary with the atmospheric conditions.

  7. Effect of UV irradiation on the dynamics of oxygen and water interaction with carbon nanotubes

    Nelson, Anthony J [Virginia Tech, Blacksburg, VA; Ivanov, Ilia N [ORNL

    2016-01-01

    Carbon nanotube (CNT) films composed of semiconducting single wall nanotubes (s-SWNTs), metallic single wall nanotubes (m-SWNTs), and multiwall nanotubes (MWNTs) were exposed to O2 and H2O vapor in the dark and under UV irradiation. Changes in the film conductivity and mass were measured in situ. We find that UV irradiation increases the resistive response of CNT films to O2 and H2O by more than an order of magnitude. In m-SWNT and MWNT films, UV irradiation changes the sign of the resistive response to O2 and H2O by generating free charge carriers. S-SWNTs show the largest UV-induced resistive response and exhibit weakening of van der Waals interactions with the QCM crystal when exposed to gas/vapor.

  8. Irradiation uniformity of spherical targets by multiple uv beams from OMEGA

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

  9. Was UV spectral solar irradiance lower during the recent low sunspot minimum?

    Lockwood, Mike

    2011-01-01

    A detailed analysis is presented of solar UV spectral irradiance for the period between May 2003 and August 2005, when data are available from both the Solar Ultraviolet pectral Irradiance Monitor (SUSIM) instrument (on board the pper Atmosphere Research Satellite (UARS) spacecraft) and the Solar Stellar Irradiance Comparison Experiment (SOLSTICE) instrument (on board the Solar Radiation and Climate Experiment (SORCE) satellite). The ultimate aim is to develop a data composite that can be use...

  10. Enhancing disinfection by advanced oxidation under UV irradiation in polyphosphate-containing wastewater flocs.

    Azimi, Y; Allen, D G; Farnood, R R

    2014-05-01

    In this paper, the role of naturally occurring polyphosphate in enhancing the ultraviolet disinfection of wastewater flocs is examined. It was found that polyphosphate, which accumulates naturally within the wastewater flocs in the enhanced biological phosphorus removal process, is capable of producing hydroxyl radicals under UV irradiation and hence causing the photoreactive disinfection of microorganisms embedded within flocs. This phenomenon is likely responsible for the improved UV disinfection of the biological nutrient removal (BNR) effluent compared to that of conventional activated sludge effluent by as much as 1 log. A mathematical model is developed that combines the chemical disinfection by hydroxyl radical formation within flocs, together with the direct inactivation of microorganisms by UV irradiation. The proposed model is able to quantitatively explain the observed improvement in the UV disinfection of the BNR effluents. This study shows that the chemical composition of wastewater flocs could have a significant positive impact on their UV disinfection by inducing the production of oxidative species. PMID:24568787

  11. Replication of adeno-associated virus in cells irradiated with UV light at 254 nm

    Yakobson, B.; Hrynko, T.A.; Peak, M.J.; Winocour, E.

    1989-03-01

    Irradiation of simian virus 40 (ori mutant)-transformed Chinese hamster embryo cells (OD4 line) with UV light induced a cellular capacity which supported a full cycle of helper-independent adeno-associated virus replication. Monochromatic UV light at 254 nm was about 1,000-fold more effective than UV light at 313 nm, indicating that cellular nucleic acid is the primary chromophore in the UV-induced process leading to permissiveness for adeno-associated virus replication. The UV irradiation and the infection could be separated for up to 12 h without substantial loss of permissiveness. During this time interval, the induction process was partly sensitive to cycloheximide, suggesting a requirement for de novo protein synthesis.

  12. Effect of aerosols on solar UV irradiances during the Photochemical Activity and Solar Ultraviolet Radiation Campaign

    Kylling, A.; Bais, A. F.; Blumthaler, M.; Schreder, J.; Zerefos, C. S.; Kosmidis, E.

    1998-10-01

    Surface UV irradiances were measured at two different sites in Greece during June 1996 under noncloudy conditions. The measured UV irradiances are simulated by a radiative transfer model using measured ozone density and aerosol optical depth profiles. The absolute difference between model and measurements ranges between -5% and +5% with little dependence on wavelength. The temporal and solar zenith angle dependence in the difference between model and measurement suggests that part of this difference may be explained by assumptions made about the aerosol single-scattering albedo and phase function. Simulated spectra including aerosols are compared with calculated spectra excluding aerosols. It is found that for otherwise similar atmospheric conditions the UVB irradiance is reduced with respect to aerosol free conditions by 5% to 35% depending on the aerosol optical depth and single-scattering albedo. For the campaign period, changes in the aerosol loading gave larger variations in the surface UV irradiances than the changes seen in the ozone column.

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

    The cellular and molecular basis of the therapeutically used effect of reinjected ultraviolet (UVC) irradiated blood is unknown. First approaches to that problem were made in this study by aid of model experiments. Neither the spontaneous degranulation nor the antigen-induced histamine release from rat connective tissue mast cells (in vivo) was influenced by the injection (i.v.) of UV-irradiated blood or blood lymphocytes. By comparison of the effect of UV light on blood lymphocytes (number of dead cells, strength of chemoluminescence) after irradiation of the isolated cells and the unfractionated blood, respectively, it was shown that the strong light absorption within the blood sample prevents damage or functional alterations of the blood lymphocytes. The compound 48/80 - induced histamine release from rat peritoneal mast cells can be completely inhibited by UV irradiation (0.6 mJ/cm2) without increasing the spontaneous histamine release. (author)

  14. Acute whole body UVA irradiation combined with nitrate ingestion enhances time trial performance in trained cyclists.

    Muggeridge, David J; Sculthorpe, Nicholas; Grace, Fergal M; Willis, Gareth; Thornhill, Laurence; Weller, Richard B; James, Philip E; Easton, Chris

    2015-08-01

    Dietary nitrate supplementation has been shown to increase nitric oxide (NO) metabolites, reduce blood pressure (BP) and enhance exercise performance. Acute exposure to ultraviolet (UV)-A light also increases NO bioavailability and reduces BP. We conducted a randomized, counterbalanced placebo-controlled trial to determine the effects of UV-A light alone and in combination with nitrate on the responses to sub-maximal steady-state exercise and time trial (TT) performance. Nine cyclists (VO2max 53.1 ± 4.4 ml/kg/min) completed five performance trials comprising 10 min submaximal steady-state cycling followed by a 16.1 km TT. Following a familiarization the final four trials were preceded, in random order, by either (1) Nitrate gels (NIT) + UV-A, (2) Placebo (PLA) + UV-A, (3) NIT + Sham light (SHAM) and (4) PLA + SHAM (control). The NIT gels (2 × 60 ml gels, ~8.1 mmol nitrate) or a low-nitrate PLA were ingested 2.5 h prior to the trial. The light exposure consisted of 20 J/cm(2) whole body irradiation with either UV-A or SHAM light. Plasma nitrite was measured pre- and post-irradiation and VO2 was measured continuously during steady-state exercise. Plasma nitrite was higher for NIT + SHAM (geometric mean (95% CI), 332 (292-377) nM; P = 0.029) and NIT + UV-A (456 (312-666) nM; P = 0.014) compared to PLA + SHAM (215 (167-277) nM). Differences between PLA + SHAM and PLA + UV-A (282 (248-356) nM) were small and non-significant. During steady-state exercise VO2 was reduced following NIT + UVA (P = 0.034) and tended to be lower in NIT + SHAM (P = 0.086) but not PLA + UV-A (P = 0.381) compared to PLA + SHAM. Performance in the TT was significantly faster following NIT + UV-A (mean ± SD 1447 ± 41 s P = 0.005; d = 0.47), but not PLA + UV-A (1450 ± 40 s; d = 0.41) or NIT + SHAM (1455 ± 47 s; d = 0.28) compared to PLA + SHAM (1469 ± 52 s). These findings demonstrate that exposure to UV-A light alone does not alter the physiological responses to exercise or improve

  15. Comparison of the efficacy of gamma and UV irradiation in sanitization of fresh carrot juice

    As there is no pasteurization procedure for the manufacture of fresh vegetable juice, both industry and consumers have sought a method for improving the storage stability and shelf-life of this category of products. In this study, the effects of commercially available, non-thermal pasteurization processes, such as gamma and UV irradiation, were compared for their efficacy in sanitizing fresh carrot juice (FCJ). FCJ was manufactured, packaged, and gamma irradiated with doses of 0, 1, 3, and 5 kGy. The manufactured FCJ was also passed through 4 UV light lamps at doses of 3.67, 4.69, and 6.50 kGy. The total aerobic bacterial count of the FCJ approached the legal limit (105 CFU/mL) after manufacturing. Both treatments were effective in reducing the number of total aerobic bacteria, and the reduced number was maintained during storage for 7 days. Gamma irradiation was more effective in suppressing microbial growth during storage. When the doses for UV treatment and gamma irradiation were higher, the inactivation effects were higher. The reduction of ascorbic acid content was greater upon gamma irradiation than UV treatment. No difference was found in the contents of flavonoids and polyphenols in FCJ after either treatment. After 3 days of refrigerated storage, the sensory scores of gamma- or UV-irradiated FCJ were superior to those of the control. The results indicate that both non-thermal treatments were effective in improving storage stability and extending shelf-life, but gamma irradiation was slightly better in suppressing microbial growth after treatment. - Highlights: ► Gamma irradiation and UV treatment were compared for their efficacy in sanitizing fresh carrot juice. ► Both treatments were effective in reducing the number of total aerobic bacteria but gamma irradiation was more effective. ► Reduction of ascorbic acid content was greater by gamma irradiation than by UV treatment. ► Sensory scores of gamma irradiated or UV-treated carrot juice were

  16. UV solar irradiance in observations and the NRLSSI and SATIRE-S models

    Yeo, K. L.; Ball, W. T.; Krivova, N. A.; Solanki, S. K.; Unruh, Y. C.; Morrill, J.

    2015-08-01

    Total solar irradiance and UV spectral solar irradiance has been monitored since 1978 through a succession of space missions. This is accompanied by the development of models aimed at replicating solar irradiance by relating the variability to solar magnetic activity. The Naval Research Laboratory Solar Spectral Irradiance (NRLSSI) and Spectral And Total Irradiance REconstruction for the Satellite era (SATIRE-S) models provide the most comprehensive reconstructions of total and spectral solar irradiance over the period of satellite observation currently available. There is persistent controversy between the various measurements and models in terms of the wavelength dependence of the variation over the solar cycle, with repercussions on our understanding of the influence of UV solar irradiance variability on the stratosphere. We review the measurement and modeling of UV solar irradiance variability over the period of satellite observation. The SATIRE-S reconstruction is consistent with spectral solar irradiance observations where they are reliable. It is also supported by an independent, empirical reconstruction of UV spectral solar irradiance based on Upper Atmosphere Research Satellite/Solar Ultraviolet Spectral Irradiance Monitor measurements from an earlier study. The weaker solar cycle variability produced by NRLSSI between 300 and 400 nm is not evident in any available record. We show that although the method employed to construct NRLSSI is principally sound, reconstructed solar cycle variability is detrimentally affected by the uncertainty in the SSI observations it draws upon in the derivation. Based on our findings, we recommend, when choosing between the two models, the use of SATIRE-S for climate studies.

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

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

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

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

    1983-08-01

    The carcinogenic effect of artificial UV sunlight followed by UV-A irradiation in human solaria doses has been studied with the use of the hairless mouse as an animal model. Artificial sunlight exposure alone induced only a moderate skin tumor incidence (animals with at least one tumor) of 0.15 after one year, and UV-A irradiation alone induced no tumor formation. However, the combination of artificial sunlight exposure and subsequent UV-A irradiation significantly increased the tumor incidence to 0.72. We conclude that, in humans, tanning with UV-A for cosmetic purposes may not be an innocuous procedure. PMID:6870317

  19. Efficacy of uv irradiation in the microbial disinfection of marine mammal water

    A study was made on the efficacy of a commercial ultraviolet (UV) sterilizer in reducing the number of bacteria and yeasts in a saline, closed-system marine mammal complex. UV irradiation was effective in lowering bacterial counts in the effluent of the unit (greater than 75% reduction), but bacteria in more remote parts of the water system reached levels equal to or greater than pre-UV counts. Yeast reduction was considerably less, and a trend similar to that of the bacteria was observed in remote sections of the water system. It is concluded that UV irradiation is of limited value in the disinfection of marine mammal water. Factors contributing to the poor performance of the sterilizer were the long recycle time of the water and lack of a residual effect

  20. Decreased influenza virus pathogenesis by infection with germicidal UV-irradiated airborne virus

    Respiratory infections are acquired by the inhalation of airborne microorganisms. To evaluate the effect of germicidal UV-irradiation on airborne contagion, infectious clouds of influenza A/PR8/34 virus were generated and exposed to known intensities of UV. Thereafter, the airborne virus was used to infect mice wherein the pathogenesis of the viral pneumonia was evaluated. Increasing doses of UV inactivated infectious airborne virus in a dose-dependent manner and reduced the mortality rates as compared to an infectious cloud of untreated virus. When a sublethal cloud of infectious virus was used, UV-irradiation modified the viral infection, as quantified by pulmonary virus titers, from a severe pneumonitis to a milder form of the disease. (author)

  1. Is Weigle-mutagenesis in uv-irradiated bacteriophage lambda a myth

    It is argued that Weigle-mutagenesis, a higher mutation frequency observed when uv-irradiated are allowed to infect uv-irradiated bacteria, is often a trivial artifact rather than a manifestation of an error-prone bacterial DNA repair. It may occur due to the slower replication of irradiated phages which results in more replication taking place when a mutator polymerase activity has become induced and expressed than is the case with intact phages. The mutator polymerase activity is inducible in recA+ cells but it is not under the control of the lexA repressor. Weigle-mutagenesis under these conditions is untargeted and is not a good model for bacterial uv mutagenesis. 12 references

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

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

  3. U.V. enhanced reactivation of U.V.- and #betta#-irradiated adenovirus in Cockayne syndrome and Xeroderma pigmentosum fibroblasts

    U.V.-enhanced reactivation (UVER) of both U.V.-irradiated and #betta#-irradiated human adenovirus type 2 (Ad 2) was examined following the infection of a variety of Cockayne Syndrome (CS) and Xeroderma pigmentosum (XP) fibroblast strains which had been pre-irradiated with U.V. light. U.V.-irradiated or non-irradiated fibroblasts were infected with either non-irradiated or irradiated Ad 2, and at 48 hours after infection cells were examined for the presence of viral structural antigens (Vag) using immunofluorescent staining. (author)

  4. Titanium dioxide nanoparticles detoxify pirimicarb under UV irradiation at ambient intensities.

    Seitz, Frank; Bundschuh, Mirco; Dabrunz, André; Bandow, Nicole; Schaumann, Gabriele E; Schulz, Ralf

    2012-03-01

    Titanium dioxide nanoparticles (nTiO₂) form reactive oxygen species (ROS) under irradiation by ultraviolet light (UV). This known photocatalytic activity may finally affect the presence and toxicity of organic environmental chemicals, which have not yet been studied at ambient UV intensity. The authors used a three-factorial design to evaluate the interaction of the carbamate insecticide pirimicarb (initial nominal concentration, 20 µg/L), ambient UV irradiation (40 W/m² for 15 min), and nTiO₂(~100 nm; 2.0 mg/L). Pirimicarb, pirimicarb × UV, and pirimicarb × nTiO₂ treatments revealed a median immobilization of Daphnia magna after 72 h ranging between 70 and 80%. This effect seemed to be caused by the initial nominal pirimicarb concentration. However, UV irradiation before an exposure of daphnids in the presence of 2.0 mg nTiO₂/L reduced pirimicarb concentrations to values below the limit of quantification, likely because of the formation of ROS. This reduction was associated with an almost complete removal of toxicity for D. magna. Furthermore, during a second experiment, 0.2 mg nTiO₂/L in combination with 15 min UV irradiation reduced pirimicarb concentrations by approximately 30%. These results indicate a detoxification and therefore remediation potential of the combined application of nTiO₂ and UV irradiation at ambient levels. This potential has not been documented to date in surface waters, where nTiO₂ concentrations in the low to medium µg/L range may occur. PMID:22170593

  5. Comparison of UV irradiance measurements at Summit, Greenland; Barrow, Alaska; and South Pole, Antarctica

    G. Bernhard

    2008-08-01

    Full Text Available An SUV-150B spectroradiometer for measuring solar ultraviolet (UV irradiance was installed at Summit, Greenland, in August 2004. Here we compare the initial data from this new location with similar measurements from Barrow, Alaska, and South Pole. Measurements of irradiance at 345 nm performed at equivalent solar zenith angles (SZAs are almost identical at Summit and South Pole. The good agreement can be explained with the similar location of the two sites on high-altitude ice caps with high surface albedo. Clouds attenuate irradiance at 345 nm at both sites by less than 6% on average, but can reduce irradiance at Barrow by more than 75%. Clear-sky measurements at Barrow are smaller than at Summit by 14% in spring and 36% in summer, mostly due to differences in surface albedo and altitude. Comparisons with model calculations indicate that aerosols can reduce clear-sky irradiance at Summit by 4–6%; aerosol influence is largest in April. Differences in total ozone at the three sites have a large influence on the UV Index. At South Pole, the UV Index is on average 20–80% larger during the ozone hole period than between January and March. At Summit, total ozone peaks in April and UV Indices in spring are on average 10–25% smaller than in the summer. Maximum UV Indices ever observed at Summit, Barrow, and South Pole are 6.7, 5.0, and 4.0, respectively. The larger value at Summit is due to the site's lower latitude. For comparable SZAs, average UV Indices measured during October and November at South Pole are 1.9–2.4 times larger than measurements during March and April at Summit. Average UV Indices at Summit are over 50% greater than at Barrow because of the larger cloud influence at Barrow.

  6. Enhanced transformation of human cells by UV-irradiated pSV2 plasmids

    Irradiating the plasmid pSV2-gpt with UV (254 nm) doses up to 200 J m-2 caused a dose-dependent increase in the yield of Gpt+ transformants when the plasmid was introduced into human cells by calcium phosphate coprecipitation. UV doses greater than 1 kJ m-2 were required to reduce the efficiency of transformation below that obtained with unirradiated DNA

  7. Enhanced transformation of human cells by UV-irradiated pSV2 plasmids

    Spivak, G.; Ganesan, A.K.; Hanawalt, P.C.

    1984-06-01

    Irradiating the plasmid pSV2-gpt with UV (254 nm) doses up to 200 J m-2 caused a dose-dependent increase in the yield of Gpt+ transformants when the plasmid was introduced into human cells by calcium phosphate coprecipitation. UV doses greater than 1 kJ m-2 were required to reduce the efficiency of transformation below that obtained with unirradiated DNA.

  8. Endonucleolytic incision of uvB irradiated DNA

    Ultraviolet irradiation of DNA produces a variety of pyrimidine damages including pyrimidine dimers and 6-4' (pyrimidin-2' one)pyrimidines. Photoalkylation, the ultraviolet irradiation of DNA in the presence of isopropanol and a free radical photoinitiator had been shown to produce 8-(2-hydroxy-2-propyl)purines. An endonuclease activity against photoalkylated DNA was found in E. coli. This was assayed by conversion of photoalkylated superhelical PM2 phage DNA to the nicked form. Comparison of enzyme activities between crude extracts of E. coli strains demonstrated a deficiency associated with a mutant lacking endonuclease III. Irradiation of the DNA substrate in the absence of isopropanol did not affect the activity in any strain studied. Therefore, the substrate photoproduct for endonuclease III is not an 8-(2-hydroxy-2-propyl)purine

  9. Effects of ultraviolet (UV) irradiation in air and under vacuum on low-k dielectrics

    Choudhury, F. A.; Ryan, E. T.; Nguyen, H. M.; Nishi, Y.; Shohet, J. L.

    2016-07-01

    This work addresses the effect of ultraviolet radiation of wavelengths longer than 250 nm on Si-CH3 bonds in porous low-k dielectrics. Porous low-k films (k = 2.3) were exposed to 4.9 eV (254 nm) ultraviolet (UV) radiation in both air and vacuum for one hour. Using Fourier Transform Infrared (FTIR) spectroscopy, the chemical structures of the dielectric films were analyzed before and after the UV exposure. UV irradiation in air led to Si-CH3 bond depletion in the low-k material and made the films hydrophilic. However, no change in Si-CH3 bond concentration was observed when the same samples were exposed to UV under vacuum with a similar fluence. These results indicate that UV exposures in vacuum with wavelengths longer than ˜250 nm do not result in Si-CH3 depletion in low-k films. However, if the irradiation takes place in air, the UV irradiation removes Si-CH3 although direct photolysis of air species does not occur above ˜242nm. We propose that photons along with molecular oxygen and, water, synergistically demethylate the low-k films.

  10. Photodegradation of dye pollutants on TiO2 pillared bentonites under UV light irradiation

    李静谊; 朱怀勇; 丁哲; 陈春城; 赵进才

    2002-01-01

    TiO2 pillared bentonite samples dried under different conditions are used to degrade 2,4-dichlorophenol and orange II under UV light irradiation. The supercritical dried sample exhibits a high activity for the photodegradation of 2,4-dichlorophenol and orange II due to its structural features. TOC and COD are measured during the degradation of 2,4-dichlorophenol under UV light irradiation using P25 and TiO2 pillared bentonite samples dried under different conditions. The clay-based catalysts can be readily separated by filtration or sedimentation.

  11. Structural transformation of CsI thin film photocathodes under exposure to air and UV irradiation

    Tremsin, A S; Siegmund, O H W

    2000-01-01

    Transmission electron microscopy has been employed to study the structure of polycrystalline CsI thin films and its transformation under exposure to humid air and UV irradiation. The catastrophic degradation of CsI thin film photocathode performance is shown to be associated with the film dissolving followed by its re-crystallization. This results in the formation of large lumps of CsI crystal on the substrate surface, so that the film becomes discontinuous and its performance as a photocathode is permanently degraded. No change in the surface morphology and the film crystalline structure was observed after the samples were UV irradiated.

  12. The total solar irradiance, UV emission and magnetic flux during the last solar cycle minimum

    Benevolenskaya, E. E.; Kostuchenko, I. G.

    2013-01-01

    We have analyzed the total solar irradiance (TSI) and the spectral solar irradiance as ultraviolet emission (UV) in the wavelength range 115-180 nm, observed with the instruments TIM and SOLSTICE within the framework of SORCE (The Solar Radiation and Climate Experiment) during the long solar minimum between the 23rd and 24th cycles. The wavelet analysis reveals an increase in the magnetic flux in the latitudinal zone of the sunspot activity, accompanied with an increase in the TSI and UV on t...

  13. Life science research using positron annihilation spectroscopy: UV-irradiated mouse skin

    Jean, Y.C. [Department of Chemistry, University of Missouri-Kansas City, Kansas City, MO 64110-2499 (United States)]. E-mail: jeany@umkc.edu; Chen, Hongmin [Department of Chemistry, University of Missouri-Kansas City, Kansas City, MO 64110-2499 (United States); Liu Guang [Department of Chemistry, University of Missouri-Kansas City, Kansas City, MO 64110-2499 (United States); Gadzia, Joseph E. [Dermatology, Department of Internal Medicine, University of Kansas Medical Center, Kansas City, KS 66103 (United States); Kansas Medical Clinic, Topeka, KS 66614 (United States)

    2007-02-15

    Positron annihilation spectroscopy (PAS) is applied to study mouse skin under different UV irradiations as a function of positron incident energy (0-30 keV). Significant variations in the depth profile of S parameter are observed in a period of hours and of days for UVA and UVB exposures, respectively. The high sensitivity of positron annihilation signals responding to UV irradiation shows that PAS may be developed as a new noninvasive technique for the detection of molecular damage in life science research.

  14. Comparison of the efficacy of gamma and UV irradiation in sanitization of fresh carrot juice

    Jo, Cheorun; Lee, Kyung Haeng

    2012-08-01

    As there is no pasteurization procedure for the manufacture of fresh vegetable juice, both industry and consumers have sought a method for improving the storage stability and shelf-life of this category of products. In this study, the effects of commercially available, non-thermal pasteurization processes, such as gamma and UV irradiation, were compared for their efficacy in sanitizing fresh carrot juice (FCJ). FCJ was manufactured, packaged, and gamma irradiated with doses of 0, 1, 3, and 5 kGy. The manufactured FCJ was also passed through 4 UV light lamps at doses of 3.67, 4.69, and 6.50 kGy. The total aerobic bacterial count of the FCJ approached the legal limit (105 CFU/mL) after manufacturing. Both treatments were effective in reducing the number of total aerobic bacteria, and the reduced number was maintained during storage for 7 days. Gamma irradiation was more effective in suppressing microbial growth during storage. When the doses for UV treatment and gamma irradiation were higher, the inactivation effects were higher. The reduction of ascorbic acid content was greater upon gamma irradiation than UV treatment. No difference was found in the contents of flavonoids and polyphenols in FCJ after either treatment. After 3 days of refrigerated storage, the sensory scores of gamma- or UV-irradiated FCJ were superior to those of the control. The results indicate that both non-thermal treatments were effective in improving storage stability and extending shelf-life, but gamma irradiation was slightly better in suppressing microbial growth after treatment.

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

    Chubarova, Nataly; Rozental', Victor

    2013-04-01

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

  16. Characterization of regulatory dendritic cells differentiated from the bone marrow of UV-irradiated mice.

    Ng, Royce L X; Scott, Naomi M; Bisley, Jackie L; Lambert, Misty J; Gorman, Shelley; Norval, Mary; Hart, Prue H

    2013-12-01

    When antigen-loaded dendritic cells (DCs) differentiated from the bone marrow (BM) of UV-irradiated mice (UV-BMDCs) were adoptively transferred into naive mice or mice pre-sensitized with that antigen, the recipients exhibited a reduced immune response following antigen challenge. Hence, UV-BMDCs are poorly immunogenic and can suppress pre-existing immunity. The UV-induced effect on BM-derived DCs was rapid (observed 1 day after UV radiation), long-lasting (observed 10 days after UV radiation) and UV dose-dependent. The mechanism by which UV-BMDCs could regulate immunity was investigated. The CD11c(+) cells, differentiated using granulocyte-macrophage colony-stimulating factor + interleukin-4, were confirmed to be DCs because they did not express the myeloid-derived suppressor cell marker, Gr1. UV-BMDCs did not display altered antigen uptake, processing or ability to activate T cells in vitro. When gene expression in UV-BMDCs and DCs differentiated from the BM of non-irradiated mice (control-BMDCs) was examined, Ccl7, Ccl8 and CSF1R (CD115) mRNA transcripts were up-regulated in UV-BMDCs compared with control-BMDCs. However, neutralizing antibodies for Ccl7 and Ccl8 did not abrogate the reduced immunogenicity of UV-BMDCs in vivo. Moreover, the up-regulation of CSF1R transcript did not correspond with increased receptor expression on UV-BMDCs. The phenotypes of UV-BMDCs and control-BMDCs were similar, with no difference in the expression of CD4, CD8α, CD103, B220 or F4/80, or the regulatory molecules CCR7 (CD197), FasL (CD95L), B7H3 (CD276) and B7H4. However, PDL1 (CD274) expression was reduced in UV-BMDCs compared with control-BMDCs following lipopolysaccharide stimulation. In summary, UV-BMDCs do not express the classical phenotypic or gene expression properties of DCs reported by others as 'regulatory' or 'tolerogenic'. PMID:23826713

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

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

  18. Physiological alterations in UV-irradiated cells: liquid holding recovery

    The biochemical and physiological alterations that occur in ultraviolet irradiated cells, during liquid holding have been studied. Incubation in buffer acts not to interfer directly with the mechanic repairs but by promoting metabolic alterations that would block some irreversible and lethal physiological responses. (L.M.J.)

  19. Repair of UV-irradiated plasmid DNA in excision repair deficient mutants of Saccharomyces cerevisiae

    The repair of UV-irradiated DNA of plasmid YEp13 was studied in the incision defective strains by measurement of cell transformation frequency. In Saccharomyces cerevisiae, rad1,2,3 and 4 mutants could repair UV-damaged plasmid DNA. In Escherichia coli, uvrA mutant was unable to repair UV-damaged plasmid DNA; however, pretreatment of the plasmid with Micrococcus luteus endonuclease increased repair. It was concluded that all the mutations of yeast were probably limited only to the nuclear DNA. (author)

  20. Dithiothreitol pretreatment and inducible repair in UV-irradiated Escherichia coli K12 cells

    The UV radiation survival of several Escherichia coli K12 strains was measured after pretreatment with dithiothreitol (DTT). In DNA repair-competent cells, UV survival was enhanced (ER = 1.2) after pretreating cells for 1.0h using 10 mmol dm-3 DTT and then incubating cells for 1.5h in buffer before UV irradiation. Similar experiments using the excision repair mutant, AB1886μυr A6, or the recombination repair and SOS-deficient mutant, AB2462recA, strains did not show enhanced UV survival. None of the E. coli strains tested were protected against UV killing by simultaneous treatment with DTT (10 mmol dm-3). These results, and the fact that incubation in chloramphenicol removed the wild-type response in DTT-pretreated, UV-irradiated cells, suggest that observed UV radioprotection was a result of inducible enzymatic repair processes such as recA-dependent repair. The proposed stimulus for inducible repair in these cells is DNA damage caused by intracellular hydroxyl radicals arising from thiol oxidation. The involvement of oxygen radicals in the induction pathway is supported by results that showed superoxide dismutase and catalase could inhibit a portion (one-third) of the inducible repair. (author)

  1. Autotransfusion of UV-irradiated blood for obliterating vascular diseases in the lower extremities

    Knott's autotransfusion of UV-irradiated blood was performed in 163 inoperable patients, including 141 patients with obliterating atherosclerosis and 22 patients with endarteritis. Good clinical effect was produced that was particularly apparent in patients with obliterating atherosclerosis. Assessment of the effects of autotransfusion of US-irradiated blood on microcirculation, peripheral circulation, hemostasis and humoral immunity in the two samples confirmed the method's efficiency

  2. Changes in the Microbiological Characteristics of Korean Native Cattle (Hanwoo) Beef Exposed to Ultraviolet (UV) Irradiation Prior to Refrigeration.

    Kim, Hyun-Jung; Lee, Yong-Jae; Eun, Jong-Bang

    2014-01-01

    The effects of ultraviolet (UV) radiation were investigated with regards to the microbial growth inhibitory effect on the shelf life of Korean native cattle (Hanwoo) beef prior to refrigerated storage. The Hanwoo samples were exposed to UV radiation (4.5 mW/cm(2)) for 0, 5, 10, 15, and 20 min. The UV-irradiated beef that was exposed for 20 min showed significantly reduced mesophilic and psychrotrophic bacterial populations to the extent of approximately 3 log cycles, as compared to that of non-irradiated beef. About 2.5 Log CFU/g of mesophilic bacteria were different compared with UV-irradiated and nonirradiated meat. UV irradiation showed the most significant growth inhibition effects on mesophilic and psychrotrophic bacteria. Coliform and Gram-negative bacteria were also reduced by 1 log cycle. The population of L. monocytogenes, S. Typhimurium, and E. coli O157:H7 decreased significantly to 53.33, 39.68, and 45.76% after 10 min of UV irradiation. They decreased significantly to 84.64, 80.76, and 84.12%, respectively, after 20 min of UV irradiation. The results show that UV irradiation time and the inhibitory effect were proportional. These results verified that UV radiation prior to refrigeration can effectively reduce the number of pathogenic bacteria on the surface of meat and improve the meat's microbial safety. PMID:26761679

  3. Repair studies in vitro of the DNA damage induced in human lymphocytes irradiated by UV

    The aim of this study was to estimate the repair capacity of DNA damage in UV irradiated human lymphocytes. The estimation of the DNA damage was done with the use of a single cell gel electrophoresis method (SCGE), also known as the Comet assay. In our investigation, previously cryopreserved lymphocytes were irradiated with UV at different doses, and DNA damage was estimated after various times of incubation. To study the biological effects of the dependence on UV exposure we have examined the level of the DNA damage in human lymphocytes after 1 hour of incubation. There was observed almost a linear increase of the DNA damage in the range of doses from 0 to 18 J/m2. To examine an influence of cell cycle (G0 stage or proliferating cells) on the repair efficiency, UV irradiated lymphocytes were incubated with or without the presence of LF-7. Results showed a statistically significant influence of the LF-7 on the repair of DNA damage induced by different doses of UV. (author)

  4. Structural Evolution of Human Recombinant alfaB-Crystallin under UV Irradiation

    Sugiyama, Masaaki; Fujii, Noriko; Morimoto, Yukio;

    2008-01-01

    External stresses cause certain proteins to lose their regular structure and aggregate. In order to clarify this abnormal aggregation process, a structural evolution of human recombinant aB-crystallin under UV irradiation was observed with in situ small-angle neutron scattering. The abnormal...

  5. Experience of autotransfusion application of UV-irradiated blood in children dermatology

    Autotransfusion of blood, irradiated by medium doses of UV radiation (254 nm), causes a stable clinical effect in children with chronic pyodermatitis and psoriasis in progressing stage, but not with allergodermatitis. Simultaneously the equilibrium in the links of vegetative nervous system is normalized, humoral immunity is activated

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

    Guo, Yong

    2012-09-27

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

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

    Cao, M.H.; Wang, B.B.; Yu, H.S.; Wang, L.L.; Yuan, S.H. [Environmental Science Research Institution, College of Environment Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Chen, J., E-mail: chenjing@mail.hust.edu.cn [Environmental Science Research Institution, College of Environment Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2010-07-15

    The photochemical decomposition of perfluorooctanoic acid (PFOA) in aqueous periodate (IO{sub 4}{sup -}) 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{sub 4}{sup -} 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{sub 3}{center_dot}) generated by photolysis of IO{sub 4}{sup -} initiated the oxidation of PFOA in UV process. Aquated electrons (e{sub aq}{sup -}), generated from water homolysis, scavenged IO{sub 4}{sup -} 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.

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

    CAF-MM1 cells derived from a goldfish have photoreactivability for the damage induced by ultraviolet light. When UV-irradiated cells were incubated in the dark at 260C, the longest interval in which photoreactivation (PR) was observed, measured by colony formation technique, was about 30h after the UV irradiation. However, if the cells were incubated at 200C, the effective time was prolonged. Since each time appeared to correspond to the doubling time of the cells at each temperature, the loss of photoreactivability is suggested to be closely related to cell growth or progression of cell cycle. The loss of PR was not observed in the cells held in confluence up to 48h after UV irradiation. Photoreactivating enzyme in growing CAF-MM1 cells incubated in the dark for 24h after UV irradiation was shown to be active, so that it is not possible that the cause of the loss of PR is change in the activity of photoreactivating enzyme. (author)

  9. Method to harden coating masses made of unsaturated polyesters and partly polymerizable monomers by UV irradiation

    A method to harden mixtures of unsaturated polyesters and partly polymerizable monomeric compounds by UV irradiation is described. The material to be coated is first coated with photo sensitizers and then with the mixture of unsaturated polyesters and monomeric compounds. (HK)

  10. Degradation mechanism of silicone glues under UV irradiation and options for designing materials with increased stability

    Fischer, H.R.; Semprimoschnig, C.; Mooney, C.; Rohr, T.; Eck, E.R.H. van; Verkuijlen, M.H.W.

    2013-01-01

    The degradation of silicone glues used, for example, in the assembly of solar modules for use in space, has been investigated and possible mechanisms which lead to colouration and possible embrittlement are analysed. Both effects are connected to the generation of radicals upon exposure to UV irradi

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

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

  12. Initial rates of DNA incision in UV-irradiated human cells

    Following UV-irradiation and in the presence of inhibitors of DNA synthesis (hydroxyurea and 1-β-D-arabinofuranosylcytosine) human cells accumulate strand breaks in their DNA - as a result of enzymic incision without subsequent rejoining. We have developed a sensitive procedure which makes stringent use of these inhibitors so as to maximize the frequency of breaks detected after low levels of UV (0.25 - 10 Jm-2) and to permit analysis of the kinetics of break accumulation over short intervals after irradiation (up to 90 min). Since the rate of accumulation of breaks declines quickly with time of incubation (not simply as a consequence of substrate depletion), we have calculated initial rate constants by extrapolating to zero time for a range of UV doses (i.e. different substrate concentrations). (orig./AJ)

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

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

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

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

    2006-01-01

    /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 in...... rats from all groups except UV+IR-irradiated. The combined UV+IR light, corresponding to solar radiation, had no negative effects on redox homeostasis in rats. Furthermore, L-ascorbic acid showed antioxidative properties by increasing the concentration of Total Antioxidative State (TAS) in plasma......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...

  15. Parameters for control of an UV-irradiation plant for the disinfection of waste water. Parameter fuer die Regelung einer UV-Anlage zur Desinfektion von Abwasser

    Rudolph, K.U. (Lehrstuhl fuer Umwelttechnik und Umweltmanagement, Univ. Witten/Herdecke (Germany)); Boettcher, J. (Lehrstuhl fuer Umwelttechnik und Umweltmanagement, Univ. Witten/Herdecke (Germany)); Nelle, T. (Lehrstuhl fuer Umwelttechnik und Umweltmanagement, Univ. Witten/Herdecke (Germany))

    1994-09-01

    A pilot-study with a small UV irradiation unit was done on different wastewater treatment plants to investigate the influence of UV-transmittance, turbidity and flow rate. The on-line measurement of these parameters with the parallel microbiological analysis shows the expected increase of total coliform-concentrations with higher turbidity or lower transmittance. Using the measurement of flow rate, transmittance and turbidity for controling of full-scale UV-plants the operation costs can be decreased. (orig.)

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

    Two biological effects of UV radiation upon Smittia eggs are observed, both of which seem to be associated with the formation of pyrimidine dimers in the RNA (largely ribosomal) of the eggs. While irradiation of the anterior pole region causes the formation of an aberrant segment pattern (double abdomen induction), irradiation of entire eggs leads to an arrest of their development (inactivation). Both UV effects are photoreversible with different action spectra of the photoreactivating light. A dose rate dependence of the photoreactivation can be observed after both UV effects. The saturating dose rate is about 6 W/m2 (at 440 nm) after UV induction of double abdomens. Upon UV inactivation, the saturating dose rate level for the photoreactivating light is much higher, and a single light flash causes both a considerable biological reactivation and the disappearance of about 7 x 109 pyrimidine dimers from the total RNA per egg. The results indicate the presence of heterogeneous light-dependent repair activities acting upon UV induced pyrimidine dimers in the RNA of the eggs. (author)

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

    More than 30 isolates of Cochliobolus sativus, the causal agent of common root rot disease; were collected from different regions of Syria. Seven of them were exposed to UV-C light for 40 or 60 h . at a dose rate of 2.52x10-3 W/cm2. A significant increases in the mycelium growth and sporulation were detected (p<0.001). Within the studied range of UV wave length, these two parameters were increased upon increasing the period of exposure to UV-C light. The pathogenicity of four isolates was evaluated after 60 h. of UV irradiation. The response to UV irradiation varied among these isolates, and resulted in an increase in their virulence level (as assessed by evaluating disease severity on sub-crown internodes). Five barley genotypes possessing different levels of resistance to C. sativus were studied. Arabi Abiad was the most susceptible cultivar whereas, Taka 76 line was moderately susceptible. It is concluded that it is possible to implement the positive effect of low doses of UV-C in stimulating the sporulation of fungi, which are difficult to sporulate on artificial media. (author)

  18. Effects of UV-B irradiation on growth, survival, pigmentation and nitrogen metabolism enzymes in Cyanobacteria

    Sinha, R.P.; Hader, D.P. [Institut fuer Botanik und Pharmazeutische Biologie, Friedrich-Alexander Universitaet, Erlangen (Germany); Kumar, H.D.; Kumar, A. [Banaras Hindu University, Varanasi (India)

    1995-12-31

    The effects of artificial UV-B irradiation on growth, survival, pigmentation, nitrate reductase (NR), glutamine synthetase (GS) and total protein profile have been studied in a number of N{sub 2}-fixing cyanobacterial strains isolated from rice (paddy) fields in India. Different organisms show different effects in terms of growth and survival. Complete killing of Anabaena sp. and Nostoc carmium occurs after 120 min of UV-B exposure, whereas the same occurs only after 150 min of exposure in the case of Nostoc commune and Scytonema sp. Growth patterns of the cells treated with UV-B revealed that Nostoc commune and Scytonema sp. are comparatively more tolerant than Anabaena sp. and Nostoc carmium. Pigment content, particularly phycocyanin, was severely decreased following UV-B irradiation in all strains tested so far. In vivo NR activity was found to increase, while in vivo GS activity was decreased following exposure to UV-B for different durations in all test organisms; although complete inhibition of GS activity did not occur even after 120 min of UV-B exposure. (author). 37 refs, 6 figs.

  19. Effects of UV-B irradiation on growth, survival, pigmentation and nitrogen metabolism enzymes in Cyanobacteria

    The effects of artificial UV-B irradiation on growth, survival, pigmentation, nitrate reductase (NR), glutamine synthetase (GS) and total protein profile have been studied in a number of N2-fixing cyanobacterial strains isolated from rice (paddy) fields in India. Different organisms show different effects in terms of growth and survival. Complete killing of Anabaena sp. and Nostoc carmium occurs after 120 min of UV-B exposure, whereas the same occurs only after 150 min of exposure in the case of Nostoc commune and Scytonema sp. Growth patterns of the cells treated with UV-B revealed that Nostoc commune and Scytonema sp. are comparatively more tolerant than Anabaena sp. and Nostoc carmium. Pigment content, particularly phycocyanin, was severely decreased following UV-B irradiation in all strains tested so far. In vivo NR activity was found to increase, while in vivo GS activity was decreased following exposure to UV-B for different durations in all test organisms; although complete inhibition of GS activity did not occur even after 120 min of UV-B exposure. (author)

  20. Simulation of ozone depletion using ambient irradiance supplemented with UV lamps.

    Díaz, S; Camilión, C; Escobar, J; Deferrari, G; Roy, S; Lacoste, K; Demers, S; Belzile, C; Ferreyra, G; Gianesella, S; Gosselin, M; Nozais, C; Pelletier, E; Schloss, I; Vernet, M

    2006-01-01

    In studies of the biological effects of UV radiation, ozone depletion can be mimicked by performing the study under ambient conditions and adding radiation with UV-B lamps. We evaluated this methodology at three different locations along a latitudinal gradient: Rimouski (Canada), Ubatuba (Brazil) and Ushuaia (Argentina). Experiments of the effect of potential ozone depletion on marine ecosystems were carried out in large outdoor enclosures (mesocosms). In all locations we simulated irradiances corresponding to 60% ozone depletion, which may produce a 130-1900% increase in 305 nm irradiance at noon, depending on site and season. Supplementation with a fixed percentage of ambient irradiance provides a better simulation of irradiance increase due to ozone depletion than supplementation with a fixed irradiance value, particularly near sunrise and sunset or under cloudy skies. Calculations performed for Ushuaia showed that, on very cloudy days, supplementation by the square-wave method may produce unrealistic irradiances. Differences between the spectra of the calculated supplementing irradiance and the lamp for a given site and date will be a function of the time of day and may become more or less pronounced according to the biological weighting function of the effect under study. PMID:17205620

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

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

    2016-09-15

    Emerging contaminants represent a wide group of the most different compounds. They appear in the environment at trace levels due to human activity. Most of these compounds are not yet regulated. Sunscreen UV-filters play an important role among these emerging contaminants. In the present research the reactions of 4-tert-butyl-4'-methoxydibenzoylmethane (avobenzone), the most common UV filter in the formulation of sunscreens, were studied under the combined influence of active chlorine and UV-irradiation. Twenty five compounds were identified by GC/MS as transformation products of avobenzone in reactions of aquatic UV-irradiation and chlorination with sodium hypochlorite. A complete scheme of transformation of avobenzone covering all the semivolatile products is proposed. The identification of the two primary chlorination products (2-chloro-1-(4-tert-butylphenyl)-3-(4-methoxyphenyl)-1,3-propanedione and 2,2-dichloro-1-(4-tert-butylphenyl)-3-(4-methoxyphenyl)-1,3-propanedione) was confirmed by their synthesis and GC/MS and NMR analysis. Although the toxicities of the majority of these products remain unknown substituted chlorinated phenols and acetophenones are known to be rather toxic. Combined action of active chlorine and UV-irradiation results in the formation of some products (chloroanhydrides, chlorophenols) not forming in conditions of separate application of these disinfection methods. Therefore caring for people «well-being» it is of great importance to apply the most appropriate disinfection method. Since the primary transformation products partially resist powerful UV-C irradiation they may be treated as stable and persistent pollutants. PMID:27258620

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

    The effects of UV-irradiation of sperm on the embryonic development of sea urchins (H. pulcherrimus, Anthocidaris crassispina, Pseudocentrotus depressus, and C. japonicus) were studied. Eggs inseminated with UV-irradiated sperm developed almost normally into blastulae without arrest of cleavage or hatching, even though they showed some division delay. Morphogenesis was disturbed in and after the gastrula stage, and the formation of normal pluteus larvae was inhibited depending on the UV dose (5 - 30 J/m2) given to the sperm. Morphological abnormalities observed were as follows: inhibition of gastrulation; abnormal delamination and random arrangement of primary mesenchymal cells onto the ectodermal wall; abnormal localization or an excess number of spicules; malformed skeletons. These developmental abnormalities were photoreactivated with high efficiency. Inhibition of pluteus formation to less than 5% by the UV-irradiation with 20 J/m2 completely recovered under fluorescent light illumination with 10 klux. By treating the eggs with brief illumination at various times after insemination, a stage-dependent change of the photoreactivation (PR) efficiency was found. PR treatment after the insemination up to the onset of the first DNA synthesizing phase was highly effective for the recovery, while the PR efficiency began to decrease during the S phase, becoming zero on and after the end of the phase. In eggs fertilized with UV-irradiated sperm, mitoses were abnormal and shromosomal bridges were formed at the anaphase of the first mitosis. Their frequency increased depending on the UV dose. The mitotic abnormality was also photoreactivated with visible light treatment after fertilization. The change in PR efficiency of the illumination was very similar to that of morphological abnormality. (Author)

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

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

  4. Rapid inactivation of seven Bacillus spp. under simulated Mars UV irradiation

    Schuerger, Andrew C.; Richards, Jeff T.; Newcombe, David A.; Venkateswaran, Kasthuri

    2006-03-01

    Seven Bacillus spp. were exposed to simulations of Mars-normal UV fluence rates in order to study the effects of UV irradiation on microbial survival. A UV illumination system was calibrated to deliver 9.78 W m -2 (35.2 kJ m -2 h -1) of UVC + UVB irradiation (200-320 nm) to microbial samples, thus creating a clear-sky simulation (0.5 optical depth) of equatorial Mars. The Bacillus spp. studied were: B. licheniformis KL-196, B. megaterium KL-197, B. nealsonii FO-092, B. pumilus FO-36B, B. pumilus SAFR-032, B. subtilis 42HS1, and B. subtilis HA101. The bacteria were prepared as thin monolayers of endospores on aluminum coupons in order to simulate contaminated spacecraft surfaces. Bacterial monolayers were exposed to Mars UV irradiation for time-steps of 0, 0.25, 0.5, 1, 5, 15, 30, 60, 120, or 180 min. The surviving endospores were then assayed with a Most Probable Numbers (MPN) procedure and with a culture-based assay that utilized a bacillus spore germination medium. Results indicated that B. pumilus SAFR-032 was the most resistant, and B. subtilis 42HS-1 and B. megaterium were the most sensitive of the seven strains exposed to martian UV fluence rates. Bacillus subtilis 42HS1 and B. megaterium were inactivated after 30 min exposure to Mars UV, while B. pumilus SAFR-032 required 180 min for full inactivation in both assays. Spores of B. pumilus SAFR-032 exhibited significantly different inactivation kinetics suggesting that this wild type isolate also was more resistant than the standard dosimetric strain, B. subtilis HA101. Although the various Bacillus spp. exhibited diverse levels of UV resistance, none were immune to UV irradiation, and, thus, all species would be expected to be inactivated on Sun-exposed spacecraft surfaces within a few tens-of-minutes to a few hours on sol 1 under clear-sky conditions on equatorial Mars. The inactivation kinetics of all seven Bacillus spp. support the conclusion that significant levels of bioload reductions are possible on

  5. UV irradiation leads to transient changes in phosphorylation and stability of tumor suppressor protein p53.

    Scheidtmann, K; Landsberg, G

    1996-12-01

    Tumor suppressor protein p53 is thought to play a crucial role in maintaining the integrity of the genome. DNA damage caused by genotoxic drugs, UV or gamma-irradiation leads to accumulation of p53 and activation of its DNA binding and transcriptional activities and subsequently to cell cycle arrest or apoptosis. We investigated whether the apparent activation of p53 might be due to post-translational modification. The rat fibroblast cell lines REF52, 208F, and rat1 were irradiated with W-A and the synthesis, stability and phosphorylation state of p53 were investigated by pulse chase experiments, SDS-PAGE and two-dimensional phosphopeptide mapping. The three cell lines exhibited different sensitivities and biological responses to UV irradiation, REF52 cells responded with a growth arrest whereas 208F and rat1 cells underwent apoptosis. The fate of p53 was similar in all cases. Both the stability of p53 and its phosphorylation increased instantaneously but transiently. However, the amount of p53 that accumulated after UV treatment was much higher in 208F and rat1 than in REF52 cells. Interestingly, p53 that was synthesized early after irradiation was stable for more than 14 h whereas molecules synthesized 8 or more hours post irradiation were increasingly susceptible to degradation. Moreover, between 14 and 20 h after treatment, the rate of synthesis of p53 decreased to a level lower than in untreated cells suggesting negative feed back control. The expression of different p53-responsive genes, waf1/cip1, Gadd45, and bax was investigated by protein analyses. Surprisingly, p21(waf1) was expressed only in REF52 cells but not in the others. Furthermore, UV irradiation led only to a moderate increase of p21(waf1) expression. Expression of Gadd45 and box was detectable in both cell types but its expression did not change significantly upon UV treatment. Our results suggest i) that both cell types share a common pathway which upon UV irradiation results in enhanced

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

    The influence of a continuous UV irradiation (emitter NN 33/89 original Hanau) during the fattening periods primarily in the bactericide region of 253.7 nm of various intensities on the spore content of air, on the state of health and on the fattening breeding of pigs was tested in two fattening procedures. The high spore number per m3 air of over 700 000 upon occupying the stall in the first fattening procedure was reduced by 90.5% to about 70 000 after 1 week of UV irradiation, and in the second procedure, from 111 500 to 16 000, i.e. a reduction of 85.5%. The spore content of the stall air then exhibited large deviations reducing and increasing. The same deviations were recorded for dust content. There was no absolute correlation between dust and spore content of the air until the 11th week after starting UV irradiation in either test. The spore content sank in the reference stalls also without UV irradiation, by 29.9% in the first fattening procedure 1 week after occupying the stall and even by 75% in the second procedure. The spore content of the air in the reference stalls also then exhibited deviations sinking and rising as in the test stalls with UV irradiation. Here too, there was no correlation between dust and spore content of the air. The spore content in the air was 2 to 7 times higher in the reference stalls than in the test stalls. One may conclude from the tests that the promoting irradiation strength is between 15 and 20 μW/cm2 and that short-term stool production in danish stalling, 60 μW/cm2 are not harmful. Air disinfection with UV irradiation, can only be part of the total hygiene measures taken in veterinary medicine and may only be considered as an important link in the chain of the health promoting and increased efficient hygiene measures in the intensification of aggriculturally useful animals. (orig./AJ)

  7. Curcumin Protects Against the Acute Inflammatory Process in Irradiated Rats

    Nutraceuticals that provide medical or health benefits, including prevention and treatment of disease may be advantageous in inflammation and exposure to radiation. The aim of this study was to investigate the potential of curcumin to modulate, counteract or prevent the inflammatory response induced in irradiated and non-irradiated rats using the carrageenan air-pouch model as an acute model. Diclofenac was used as a reference standard non-steroidal anti-inflammatory drug (NSAID). Results indicated that exposure of rats to a single dose of gamma-radiation (6 Gy) before induction of inflammation increased production of prostaglandin E2 (PGE2), tumour necrosis factor-alpha (TNF-alpha) and malondialdehyde (MDA) levels in serum. Blood glutathione (GSH) was shown to be reduced in irradiated animals. Curcumin suppressed the elevated levels of TNF-alpha, PGE2 and MDA and was able to restore blood GSH levels. Reduction in liver contents of copper (Cu), zinc (Zn), selenium (Se) and iron (Fe) was recorded after irradiation of animals before induction of inflammation. Curcumin restored the hepatic concentrations of these trace elements. The present results suggest that irradiation of rats caused marked changes in the inflammatory response while curcumin suppressed the inflammatory response in both irradiated and control animals.

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

    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

  9. Acute and delayed toxicities of total body irradiation

    Deeg, H.J.

    1983-12-01

    Total body irradiation is being used with increasing frequency for the treatment of lymphopoietic malignancies and in preparation for marrow transplantation. Acute toxicities include reversible gastroeneritis, mucositis, myelosuppression alopecia. As the success of treatment improves and more patients become long-term survivors, manifestations of delayed and chronic toxicity become evident. These include impairment of growth and development, gonadal failure and sterility, cataract formation and possibly secondary malignancies. The contribution of total body irradiation to the development of pneumonitis and pulmonary fibrosis is still poorly understood. Some of these changes are reversible or correctable, whereas others are permanent. Nevertheless, until equally effective but less toxic regimens become available, total body irradiation appears to be the treatment of choice to prepare patients with leukemia for marrow transplantation.

  10. Acute and delayed toxicities of total body irradiation

    Total body irradiation is being used with increasing frequency for the treatment of lymphopoietic malignancies and in preparation for marrow transplantation. Acute toxicities include reversible gastroeneritis, mucositis, myelosuppression alopecia. As the success of treatment improves and more patients become long-term survivors, manifestations of delayed and chronic toxicity become evident. These include impairment of growth and development, gonadal failure and sterility, cataract formation and possibly secondary malignancies. The contribution of total body irradiation to the development of pneumonitis and pulmonary fibrosis is still poorly understood. Some of these changes are reversible or correctable, whereas others are permanent. Nevertheless, until equally effective but less toxic regimens become available, total body irradiation appears to be the treatment of choice to prepare patients with leukemia for marrow transplantation

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

    Oh Sook Kwon

    2013-01-01

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

  12. Development of an Oncolytic Adenovirus with Enhanced Spread Ability through Repeated UV Irradiation and Cancer Selection.

    Wechman, Stephen L; Rao, Xiao-Mei; Cheng, Pei-Hsin; Gomez-Gutierrez, Jorge G; McMasters, Kelly M; Zhou, H Sam

    2016-01-01

    Oncolytic adenoviruses (Ads) have been shown to be safe and have great potential for the treatment of solid tumors. However, the therapeutic efficacy of Ads is antagonized by limited spread within solid tumors. To develop Ads with enhanced spread, viral particles of an E1-wildtype Ad5 dl309 was repeatedly treated with UV type C irradiation and selected for the efficient replication and release from cancer cells. After 72 cycles of treatment and cancer selection, AdUV was isolated. This vector has displayed many favorable characteristics for oncolytic therapy. AdUV was shown to lyse cancer cells more effectively than both E1-deleted and E1-wildtype Ads. This enhanced cancer cell lysis appeared to be related to increased AdUV replication in and release from infected cancer cells. AdUV-treated A549 cells displayed greater expression of the autophagy marker LC3-II during oncolysis and formed larger viral plaques upon cancer cell monolayers, indicating increased virus spread among cancer cells. This study indicates the potential of this approach of irradiation of entire viral particles for the development of oncolytic viruses with designated therapeutic properties. PMID:27314377

  13. Development of an Oncolytic Adenovirus with Enhanced Spread Ability through Repeated UV Irradiation and Cancer Selection

    Stephen L. Wechman

    2016-06-01

    Full Text Available Oncolytic adenoviruses (Ads have been shown to be safe and have great potential for the treatment of solid tumors. However, the therapeutic efficacy of Ads is antagonized by limited spread within solid tumors. To develop Ads with enhanced spread, viral particles of an E1-wildtype Ad5 dl309 was repeatedly treated with UV type C irradiation and selected for the efficient replication and release from cancer cells. After 72 cycles of treatment and cancer selection, AdUV was isolated. This vector has displayed many favorable characteristics for oncolytic therapy. AdUV was shown to lyse cancer cells more effectively than both E1-deleted and E1-wildtype Ads. This enhanced cancer cell lysis appeared to be related to increased AdUV replication in and release from infected cancer cells. AdUV-treated A549 cells displayed greater expression of the autophagy marker LC3-II during oncolysis and formed larger viral plaques upon cancer cell monolayers, indicating increased virus spread among cancer cells. This study indicates the potential of this approach of irradiation of entire viral particles for the development of oncolytic viruses with designated therapeutic properties.

  14. Improving the photocatalytic activity of graphene oxide/ZnO nanorod films by UV irradiation

    Rokhsat, Eliza; Akhavan, Omid

    2016-05-01

    Graphene oxide (GO) sheets with a low concentration (∼1 wt%) were deposited on surface of hydrothermally synthesized ZnO nanorod films. The deposited films were heat treated at 450 °C in order to achieve suitable GO/ZnO hybrid thin films for photocatalytic purposes. The photocatalytic activity of the nanocomposite films was investigated based on degradation of methylene blue (MB) dye which is a typical pollutant model. The GO/ZnO hybrid thin films could degrade higher MB (∼90%) than the bare ZnO nanorods (which showed only ∼75% degradation) after 450 min UV irradiation. A further significant improvement (resulting in a nearly complete degradation of MB) was achieved by exposing the GO/ZnO films to UV irradiation. The improvement was assigned to UV-assisted photocatalytic reduction of GO sheets and separation of photoexcited electron-hole pairs of ZnO by the UV-treated GO sheets. These results highlight application of UV treatment in improving the photocatalytic activity of GO-containing ZnO nanostructures.

  15. Antibodies to UV irradiated DNA: the monitoring of DNA damage by ELISA and indirect immunofluorescence

    The enzyme-linked immunosorbant assay (ELISA) was modified to (1) characterize antibodies raised in rabbits against UV-irradiated single-stranded DNA (UVssDNA) complexed with methylated BSA and (2) directly detect pyrimidine dimers in irradiated DNA. The antisera specifically bound to UVssDNA, UVpoly(dT) and to a limited extent to UVdsDNA and UVpoly(dC). Fifty per cent of the maximum antibody binding was observed at a 1-5000 dilution against UVssDNA. Binding to ssDNA and poly(dT) was observed only at much higher concentrations of antibody, whereas no binding to double stranded DNA (dsDNA) was observed. The extent of binding of the antibody was dependent on the UV dose to DNA and the concentration of antigen immobilized on the plate. The ability of various irradiated molecules, DNA, homopolymers and linkers to act as inhibitors of antibody binding establishes that the antigenic determinants are mainly thymine homodimers with lower affinity for cytosine dimers. Potential usefulness of the antibodies to directly quantitate pyrimidine dimers in cells exposed to UV radiation was determined by indirect immunofluorescence. Flow cytometric analysis of immunostained human lymphocytes irradiated with 254 nm radiation indicated that greater than 50% of the population had significantly higher fluorescent intensity than unirradiated cells. (author)

  16. The relationship between solar UV irradiance and total ozone from observations over southern Argentina

    Bojkov, Rumen D.; Fioletov, Vitali E.; Diaz, Susana B.

    1995-05-01

    Solar ultraviolet (UV) radiation at 300 and 305 nm, measured by a Biospherical Instruments high resolution scanning spectroradiometer at Ushuaia, southern Argentina (55 deg S, 68 deg W), as a part of the US National Science Foundation network for Polar Regions, was compared with total ozone satellite measurements. A statistical relationship between UV and total ozone was derived. On the basis of this relationship, the differences in 300 and 305 nm irradiance between 1979-1983 and 1989-1993 intervals are estimated; for October, the 15% observed decline of total ozone has led to irradiance increases of 80% at 300 nm and 35% at 305 nm. During the days with 'ozone hole' conditions, the 300 nm irradiance is as high as it would be at the summer solstice three months later, and is approximately 4 times higher than the UV irradiance corresponding to the 'normal ozone condition for early October, as further illustrated for October 1994. Inclusion of the 340 nm cloudy-dependent predictor is discussed.

  17. Surface modification of synthetic rubbers by UV, ion-etching, and low energy EB irradiation

    Surface modification processing of two kinds of synthetic rubbers (ethylene-propylene, and chloroprene) by ultraviolet (UV), sputter ion etching, and electron beam (EB) irradiation treatments has been studied in relation to the modification mechanisms. The most remarkable effect of these treatments was (1) the rapid increase of adhesion properties and (2) simultaneously decrease of self-stickiness. This non-sticking effect was particularly important for the rapid production of thin rubber sheet articles. The effectiveness was in the following order: ion etching>UV>EB. The surface modification mechanism was studied by use of SEM, ESCA, FT-IR, and related interfacial analytical procedures

  18. Photocatalytic Degradation of p-Cresol by Zinc Oxide under UV Irradiation

    Nor Azah Yusof; Yadollah Abdollahi; Abdul Halim Abdullah; Zulkarnain Zainal

    2011-01-01

    Photocatalytic degradation of p-cresol was carried out using ZnO under UV irradiation. The amount of photocatalyst, concentration of p-cresol and pH were studied as variables. The residual concentration and mineralization of p-cresol was monitored using a UV-visible spectrophotometer and total organic carbon (TOC) analyzer, respectively. The intermediates were detected by ultra high pressure liquid chromatography (UPLC). The highest photodegradation of p-cresol was observed at 2.5 g/L of ZnO ...

  19. Effect of UV-B (290-320 nm) irradiation on growth and metabolism of cucumber cotyledons

    Cucumber (Cucumis sativus L. cv. Natsusairaku 3) seedlings were grown in a growth cabinet under UV-B (290–320 nm) irradiation (equivalent to the UV-B radiation normally incident at Tokyo, 36°N latitude, during clear sky conditions in mid-april on a weighted daily fluence basis) and a UV-B-free control condition. UV-B irradiation inhibited the growth of the cotyledons, i.e. the increase in area, and increase in fresh and dry weights of the cotyledons. The greatest inhibition rate was observed in the increase in area, causing a significant increase in specific leaf weight (the ratio of weight to area). UV-B irradiation had no significant effect on DNA and RNA contents in the cotyledons, but decreased protein content slightly. In contrast, the irradiation reduced the amounts of organic acids and soluble sugars, indicating that primary carbon metabolism was very sensitive to UV-B radiation. UV-B irradiation lowered the photosynthetic activity in the cotyledons without any effect on chlorophyll content and respiratory activity. These results indicate that UV-B radiation at the ambient level may act as a physiological stress in some UV-sensitive plants. (author)

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

    Benjamin Weinkauf

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

  1. Effect of UV irradiation and Nigella sativa protective role on the mice liver tissues

    The effect of UV irradiation on liver tissues of mice before and after feeding on the Nigella sativa L. for 4 and 7 days were investigated by following the variations in their infrared spectral features. The results showed that the exposure of experimental animals to UV radiations causes considerable changes in both proteins and PO2 contents in the liver and the extent of changes depends on the energy of the source and time exposure. It was found that feeding of Nigella sativa L. during exposure for 4 days causes no significant effect on the UV induced changes in the liver tissues, while feeding for 7 days reduces the extent of the UV induced changes. Histological findings denoted that UV-Radiation causes different grades of damage in liver cells depending on the duration and type of radiation. Alcoholic extract of Nigella sativa seeds protected liver cells from being subjected to the degenerative changes. The present work investigates the possibility of applying Nigella sativa as a natural biological substance for curative purpose after UV radiation damage

  2. UV micro-irradiation of the Chinese hamster cell nucleus and caffeine post-treatment

    UV micro-irradiation of a small part of the Chinese hamster nucleus and caffeine post-incubation often results in shattered chromosomes at the first post-irradiation mitosis. In some of these mitotic cells, chromosome shattering is restricted to a few chromosomes spatially related in a small area of the metaphase spread; in others, shattering includes the whole chromosome complement. These 2 types of damage have been called partial and generalized chromosome shattering (PCS and GCS). Using antisera that specifically react with UV-irradiated DNA, we identified micro-irradiated chromatin in interphase nuclei and in mitotic cells with PCS or GCS by indirect immunofluorescence microscopy. In PCS, immunofluorescence staining was found in the damaged area, while the surrounding intact chromosomes were not stained. In GCS, staining was also restricted to a small region of the shattered chromosome complement. In other experiments, cells synchronized in G1 were micro-irradiated in the nucleus, pulse-labelled with [3H]thymidine and post-incubated with caffeine. Autoradiographs of cells with GCS showed unscheduled DNA synthesis restricted to a small chromatin region. (orig./AJ)

  3. Surface characteristics of UV-irradiated polyurethane elastomers extended with α, ω-alkane diols

    Polyurethane elastomers (PUEs) based on 4,4'-diphenylmethane diisocyanate (MDI), poly (ε-caprolactone) (PCL) and extended with series of chain extender (CE) were synthesized via two step polymerization technique. The synthesized samples were irradiated for 50, 100 and 200 h in an UV exposure unit as such the spectral distribution of the light is good match for terrestrial solar radiation. The modifications in the chemical structures of the PU before and after irradiation were characterized using Fourier transform infrared (FT-IR) technique. The effect of irradiation time and chain extenders length on surface properties were studied and investigated. Photo-oxidation of PU surface leads to fast increase in surface free energy and its polar component. Simultaneously, the work of water adhesion to polymer increases significantly during UV-irradiation. The higher changes in surface properties, observed by water absorption (%), equilibrium degree of swelling, as well as monitored by ATR-FT-IR and contact angle measurement, were found for the PU samples extended with higher number of methylene unit and irradiation time

  4. Enhanced sensing response of oxidized graphene formed by UV irradiation in water

    A small amount of defects (less than 0.01%) were introduced into graphene by irradiating it with ultraviolet (UV) light in water. The chemisorbed oxygen species caused a limited amount of degradation in the charge carrier mobility, while the physisorbed water molecules caused both a reduction in the mobility and hole doping. The oxidation was nonuniform, owing to variations in the potential caused by the metal contacts. Raman spectroscopy measurements revealed that UV irradiation in water promoted mild oxidation of graphene’s basal plane, which enhanced the electrical sensing response of the adsorption of water molecules. The enhanced electrical response was achieved by the high binding energy of the water molecules at the oxidized sites and the near-zero Dirac point voltage, easily obtained by desorbing the physisorbed water molecules. (paper)

  5. Exacerbation of lupus erythematodes visceralis as a result of UV irradiation - a hypothesis

    In the culture medium of human fibroblasts a proteolytic activity is evident after UV irradiation (290 - 320 nm). The effect of this proteolytic activity on human serum results in an electrophoretic mobility towards the anode of the C3 component of complement, which thus proves to be activated. In discussing recent and former results, a hypothesis on the exacerbation of lupus erythematodes visceralis is presented: UV irradiation causes peroxydation of lipids resulting in the release of proteolytic enzymes from lysosomal membranes and activation of the complemental system. Thus the reactivity of the immune system is increased and the disease becomes exacerbated. Further the following hypothetic aspects are discussed: porphyrins cause enhanced peroxydation of lipids, increased synthesis rate of porphyrins by drugs, decrease of lipid peroxydation by antioxidants, e.g. vitamin E, in relation to possible therapeutic effects

  6. Photocatalytic Degradation of p-Cresol by Zinc Oxide under UV Irradiation

    Nor Azah Yusof

    2011-12-01

    Full Text Available Photocatalytic degradation of p-cresol was carried out using ZnO under UV irradiation. The amount of photocatalyst, concentration of p-cresol and pH were studied as variables. The residual concentration and mineralization of p-cresol was monitored using a UV-visible spectrophotometer and total organic carbon (TOC analyzer, respectively. The intermediates were detected by ultra high pressure liquid chromatography (UPLC. The highest photodegradation of p-cresol was observed at 2.5 g/L of ZnO and 100 ppm of p-cresol. P-cresol photocatalytic degradation was favorable in the pH range of 6–9. The detected intermediates were 4-hydroxy-benzaldehyde and 4-methyl-1,2-benzodiol. TOC studies show that 93% of total organic carbon was removed from solution during irradiation time. Reusability shows no significant reduction in photocatalytic performance in photodegrading p-cresol.

  7. Oryzalexin F, a diterpene phytoalexin from UV-irradiated rice leaves

    A new rice phytoalexin, oryzalexin F, was isolated from UV-irradiated rice leaves. Its structure was established as ent-isopimara-8(14),15-diene-3β,18-diol by spectroscopic methods. The ED50 value of oryzalexin F against spore germination of the blast fungus, Pyricularia oryzae, was 103 ppm. Oryzalexin F was also produced in blast fungus-infected or jasmonic acid-treated rice leaves. (author)

  8. Expression profiling of human melanocytes in response to UV-B irradiation

    Saioa López

    2015-12-01

    Full Text Available A comprehensive gene expression analysis of human melanocytes was performed assessing the transcriptional profile of dark melanocytes (DM and light melanocytes (LM at basal conditions and after UV-B irradiation at different time points (6, 12 and 24 h, and in culture with different keratinocyte-conditioned media (KCM+ and KCM−. The data, previously published in [1], have been deposited in NCBI's Gene Expression Omnibus (GEO accession number: GSE70280.

  9. Laser-Induced Point Defects in Fused Silica Irradiated by UV Laser in Vacuum

    Xiaoyan Zhou; Xinda Zhou; Jin Huang; Qiang Cheng; Fengrui Wang; Xin Ye; Xiaodong Jiang; Weidong Wu

    2014-01-01

    High-purity fused silica irradiated by third harmonic of the Nd:YAG laser in vacuum with different laser pulse parameters was studied experimentally. Laser-induced defects are investigated by UV spectroscopy, and fluorescence spectra and correlated to the structural modifications in the glass matrix through Raman spectroscopy. Results show that, for laser fluence below laser-induced damage threshold (LIDT), the absorbance and intensity of fluorescence bands increase with laser energies and/or...

  10. Determination of selenium in freshwaters by cathodic stripping voltammetry after UV irradiation

    An analytical method was developed for the determination of total dissolved selenium in fresh waters, using linear sweep cathodic stripping voltammetry (CSV) in combination with UV photolytic digestion. Both the CSV method, based on the electrodeposition and stripping of Cu(2)Se, and the UV irradiation procedure were investigated in detail. In the presence of dissolved organic substances, as in freshwaters, Se(VI) is reduced to Se(IV) by UV irradiation in 0.1M hydrochloric acid. Glucose can be used as the carbon source in samples low in natural dissolved organic carbon (DOC). The photolytic yields of Se(IV) were about 90% in both cases. Five freshwater samples were analysed for total selenium by CSV after UV photolysis, and by hydride generation atomic absorption spectrometry (HG-AAS) after oxidative digestion followed by reduction with hydrochloric acid. The results agreed well and the concentrations were in the range 70-190 ng/l., well above the detection limit of the CSV method at 2 ng/l. (author)

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

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

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

    Hu Zu-Qing

    2013-01-01

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

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

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

    2004-10-01

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

  14. An enzymatic activity isolated from Brassica oleracea specific for UV-irradiated DNA

    As a consequence of a breakdown in the ozone layer, an increase in the amount of DNA damage caused by ultraviolet irradiation can be expected. Organisms have evolved mechanisms to repair numerous types of DNA damages. While these DNA repair systems have been well characterized in bacteria and to a lesser extent in mammalian cells, surprisingly little is known about repair of potentially harmful DNA lesions in plants. An enzyme that recognizes and incises UV irradiated DNA has been partially purified from the leaf tissue of Brassica oleracea. Glycosylase-produced base loss sites were detected by a nitrocellulose filter-binding assay using UV-irradiated PM2 viral DNA as the substrate. The optimal temperature for maximal enzyme activity is 47C with a pH optimum between 7.0 and 7.5. In addition, the endonuclease is active in both Tris and phosphate buffers, although it is stimulated by phosphate concentrations up to 25 mM. Currently, a number of synthetic polynucleotides as well as DNAs of defined sequence are being employed as substrates to determine the nature of the UV-induced lesion and the precise mechanism of action of the enzyme

  15. The Total Solar Irradiance, UV Emission and Magnetic Flux during the Last Solar Cycle Minimum

    E. E. Benevolenskaya

    2013-01-01

    Full Text Available We have analyzed the total solar irradiance (TSI and the spectral solar irradiance as ultraviolet emission (UV in the wavelength range 115–180 nm, observed with the instruments TIM and SOLSTICE within the framework of SORCE (the solar radiation and climate experiment during the long solar minimum between the 23rd and 24th cycles. The wavelet analysis reveals an increase in the magnetic flux in the latitudinal zone of the sunspot activity, accompanied with an increase in the TSI and UV on the surface rotation timescales of solar activity complexes. In-phase coherent structures between the midlatitude magnetic flux and TSI/UV appear when the long-lived complexes of the solar activity are present. These complexes, which are related to long-lived sources of magnetic fields under the photosphere, are maintained by magnetic fluxes reappearing in the same longitudinal regions. During the deep solar minimum (the period of the absence of sunspots, a coherent structure has been found, in which the phase between the integrated midlatitude magnetic flux is ahead of the total solar irradiance on the timescales of the surface rotation.

  16. Resonance energy transfer in nano-bio hybrid structures can be modulated by UV laser irradiation

    A method for targeted variation of the radiation properties of quantum dots (QDs) to control the efficiency of resonance energy transfer in nanocrystal assemblies and nano-bio hybrid materials has been developed. The method is based on strong ultraviolet (UV) laser irradiation of QDs and allows the extinction and luminescence spectra to be controlled and the luminescence quantum yield and decay kinetics to be varied. Water-soluble QDs have been synthesized and used for analyzing the effect of energy transfer from semiconductor nanocrystals on the photocycle of the photosensitive protein bacteriorhodopsin (bR) in bR–QD complexes. The UV irradiation mode has been selected in a way permitting the modulation of QD optical parameters without modification of their structure or physico-chemical properties. It is concluded that the QD interaction with bR accelerates its photocycle, but this acceleration is determined by electrostatic interactions, rather than Förster resonance energy transfer from QDs to bR. The method of UV laser irradiation of fluorescent semiconductor QDs has proven to be an efficient technique for variation of nanocrystal optical properties without affecting their structure, as well as for fine modulation of the energy transfer processes in the nanocrystal assemblies and nano-bio hybrid materials. (letter)

  17. BimL involvement in Bax activation during UV irradiation-induced apoptosis

    Bax, a proapoptotic member of the Bcl-2 family, localizes largely in the cytoplasm but translocates to mitochondria and undergoes oligomerization to induce the release of apoptogenic factors in response to apoptotic stimuli. However, the molecular mechanism of Bax activation is not fully understood. We show here the role of BimL in Bax activation during UV irradiation-induced apoptosis. In this study, GFP-BimL plasmid was constructed. The dynamic interaction between BimL and Bax during UV irradiation-induced apoptosis was observed using fluorescence resonance energy transfer (FRET) technique. Our experimental results showed that BimL translocation to mitochondria occurred before Bax translocation, and that BimL activated Bax indirectly. Moreover, inhibition of c-Jun N-terminal protein kinase (JNK) activation blocked BimL translocation, delayed and attenuated Bax translocation and subsequent apoptosis. These results demonstrate that BimL is involved in UV irradiation-induced apoptosis by indirectly activating Bax

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

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

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

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

    2004-09-01

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

  20. UV treatment and γ irradiation processing on improving porcine and fish gelatin and qualities of their premix mousse

    Porcine gelatin, fish gelatin and their mousse premixes were exposed to γ irradiation with doses ranging from 2 to 10 kGy, and to UV treatment from 10 to 30 J/m2. UV treated porcine gelatin, fish gelatin and mousse premixes, after 30 J/m2 exposure exhibited a significant increase in gel strength and gel forming ability, as well as viscosity of solutions. Gamma irradiation, up to 10 kGy, on gelatin and premixed mousse gelatin dramatically decreased the gel strength and the viscosity of the solution. UV treatment can improve the gelatin gel strength and gel forming ability of gelatin processing products. - Highlights: • UV treatment enhances the gel strength of porcine and fish gelatin. • UV treated mousse gelatin premixes exhibited better gel strength. • Gamma irradiation up to 4 kGy decreases the gel strength and viscosity of a solution

  1. Photoluminescence of hexagonal boron nitride: effect of surface oxidation under UV-laser irradiation

    Museur, Luc; Petitet, Jean-Pierre; Michel, Jean Pierre; Kanaev, Andrei V

    2008-01-01

    We report on the UV laser induced fluorescence of hexagonal boron nitride (h-BN) following nanosecond laser irradiation of the surface under vacuum and in different environments of nitrogen gas and ambient air. The observed fluorescence bands are tentatively ascribed to impurity and mono (VN), or multiple (m-VN with m = 2 or 3) nitrogen vacancies. A structured fluorescence band between 300 nm and 350 nm is assigned to impurity-band transition and its complex lineshape is attributed to phonon replicas. An additional band at 340 nm, assigned to VN vacancies on surface, is observed under vacuum and quenched by adsorbed molecular oxygen. UV-irradiation of h-BN under vacuum results in a broad asymmetric fluorescence at ~400 nm assigned to m-VN vacancies; further irradiation breaks more B-N bonds enriching the surface with elemental boron. However, no boron deposit appears under irradiation of samples in ambient atmosphere. This effect is explained by oxygen healing of radiation-induced surface defects. Formation o...

  2. MRI evaluation of rabbit bone marrow after acute irradiation

    Background: magnetic resonance imaging is a safe modality and useful in characterizing normal and abnormal bone marrow. magnetic resonance imaging also presents a more global view of bone marrow than biopsy; therefore , it may provide a better understanding of hematologic disorders. The purpose of this study was to monitor radiation-induced alterations of bone marrow in acute phase of irradiation (1-10 day after total body irradiation with conventional magnetic resonance imaging. Materials and methods: twelve New Zealand adult male white rabbits (10 for total body irradiation and 2 as controls) were irradiated to 6 Gy gamma rays. magnetic resonance imaging was performed for each rabbit femoral marrow and marginal muscles around femur region (as internal control) using T1-weighted (W) and SPIR (TR/TE 631/15) techniques before and after (24h, 48h, 72h, 5d, 10d) post total body irradiation. Results: the results were expressed as MR signal ratio (mean MR signal of femur/mean MR signal of muscle). The bone marrow MR- signal intensity values were subsequently compared to the histologic values of bone marrow cellularity, edema and hemorrhage. Values of T1-signal intensity of bone marrow for 1 to 5 days after irradiation was smaller than those the values for before irradiation data (P< 0.006) SPIR-signal intensity values of bone marrow in 3, 5 and 10 days were less than values for before irradiation (P<0.001). Since signal intensity depends to edema and hemorrhage the high correlation between cellularity and T1-signal intensity (r=0.725, P= 0.018) or SPIR-SI (r= 0.814, P 0.004) was not found. Conclusion: This study indicated that radiation-induced modification of bone marrow-signal intensity is tightly linked to the parameters like decline of all hematopoietic cell lines, edema and hemorrhage. IT was concluded that magnetic resonance imaging can distinguish normal from irradiated bone marrow so that radiation-induced alterations in bone marrow could be assessed with

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

    The optimal dose of UV-B radiation for prevention of in vivo alloimmunization (AI) against major histocompatibility complex (MHC) antigens was investigated in a murine transfusion model. Two groups with five C57BL/6 mice (H-2b) each were transfused at weekly intervals with 1 x 105 or 1 x 106 DBA/2 (H-2d) leucocytes. Both suspensions induced anti-H-2d antibodies in all mice after the second transfusion. The minimal UV-B dose required for abolition of alloreactivity in the mixed leucocyte reaction (MLR) was 0.6 J/cm2. This dose completely prevented the onset of MHC-AI in all five mice transfused with six suspensions containing 1 x 105 leucocytes. In contrast, suspensions with 1 x 106 leucocytes and exposed to 0.6 J/cm2 induced immunization in 4/5 mice. Further increase of the dose to 1.8 or 5.4 J/cm2 did not prevent the onset of MHC-AI. We conclude that the number of leucocytes per transfusion determines the efficacy of UV irradiation for the prevention of MHC-AI. For UV irradiation of human platelet concentrates (PCs) we propose to reduce the number of leucocytes by centrifugation prior to UV exposure. UV-B irradiation of PCs with high numbers of leucocytes may not be effective for prevention of alloimmunization. (Author)

  4. On the roles of solar UV irradiance and smoking on the diagnosis of second cancers after diagnosis of melanoma

    Grant, William B

    2012-01-01

    Several recent papers have reported standardized incidence ratios (SIRs) for second cancers after diagnosis of cutaneous malignant melanoma. This review divides the types of cancer into five types: (1) those for which UV-B (UVB) irradiance and vitamin D reduces risk; (2) those for which UVB/vitamin D reduces risk and smoking increases risk; (3) smoking related; (4) unknown UVB/vitamin D and smoking sensitivity and (5) those for which UV irradiance increases risk. For those in category 1, SIRs...

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

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

    1990-06-01

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

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

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

  7. The effect of UV irradiation on proliferation and life span of human diploid fibroblast-like cells

    The effect of low dose UV irradiation on the reinitiation of proliferative activity and on the life span of human diploid fibroblast-like cells is described. Cells were exposed to UV at confluence or after maintenance in an arrested state. Cell division was stimulated immediately after UV irradiation or after an additional post-UV incubation period. Arrested populations of all in vitro ages exhibited a greater sensitivity to UV and the reinitiation of proliferation was enhanced by post-UV incubation before stimulation. Ultraviolet light had no effect on life span regardless of in vitro cell age, culture state at the time of exposure, or the presence of a postirradiation period of arrest

  8. Induction of resveratrol via UV irradiation effect in Ercis callus culture

    In this study, the effect of ultraviolet (UV) irradiation time, incubation time and callus age were investigated for resveratrol induction which is a stilbene compound, in callus cultures of ‘Ercis’ grape cultivar (Vitis vinifera L.). Callus tissues were obtained from the leaves of the cuttings grown in greenhouse. Gamborg B-5 media including 2% saccarose, 0.8% agar, 1.0 µM BAP (6-benzylaminopurine) and 0.1 µM 2, 4-D (2, 4- dichlorophenoxy-acetic acid) was used as culture media. Callus tissues were sub cultured two times with 21 days intervals. After the second subculture, 12 and 15 days old callus tissues were exposed to 254 nm UV light at 10 cm distance from the source for 10 and 15 min by opening covers of the petri dishes in sterile cabin. After UV treatment, callus tissues were incubated at 25°C and in dark conditions. High Pressure Liquid Chromatography (HPLC) was used for determining of resveratrol production and concentrations were recorded at 0, 24, 48 and 72 hours after beginning of incubation. The highest resveratrol concentration (66.39 µg/g FW) was determined at 48 hours of 12 days-old callus cultures irradiated for 10 minutes. Generally, resveratrol accumulation in 12 days-old callus cultures was higher than that of 15 days-old. Both 10 min and 15 min UV irradiation periods were found to be effective for induction of resveratrol production and thus callus cultures could be convenient for resveratrol production. (author)

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

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

  10. Ultraviolet Light (UV) Inactivation of Porcine Parvovirus in Liquid Plasma and Effect of UV Irradiated Spray Dried Porcine Plasma on Performance of Weaned Pigs

    Polo, Javier; Rodríguez, Carmen; Ródenas, Jesús; Louis E Russell; Campbell, Joy M; Crenshaw, Joe D.; Torrallardona, David; Pujols, Joan

    2015-01-01

    A novel ultraviolet light irradiation (UV-C, 254 nm) process was designed as an additional safety feature for manufacturing of spray dried porcine plasma (SDPP). In Exp. 1, three 10-L batches of bovine plasma were inoculated with 105.2±0.12 tissue culture infectious dose 50 (TCID50) of porcine parvovirus (PPV) per mL of plasma and subjected to UV-C ranging from 0 to 9180 J/L. No viable PPV was detected in bovine plasma by micro-titer assay in SK6 cell culture after UV-C at 2295 J/L. In Exp. 2...

  11. Survival and mutation in clones derived from V79 Chinese hamster cells irradiated with multiple small exposures to far-UV and mid-UV

    Clones were isolated from U81 and N80 cells that were established by irradiation of Chinese hamster V79-M12G cells on a once a day schedule with 81 and 80 fractions of 6 J m/sup -2/ far-UV and 150 Jm/sup -2/ mid-UV (UV-B), respectively. These clones were examined for UV sensitivity to cell lethality and induction of mutations at 6TG/sup r/ (resistance to 6-thioguanine) and Oua/sup R/ (resistance to ouabain) loci. Survival curves for these clones indicate that their UV sensitivities to lethality vary from that of M12G cells to that of U81 and N80 parental cells. Clones also show heterogeneity for mutability to mid-UV: For induction of 6TG/sup r/, for example, non-mutable (U814), hypomutable (U815) and hypermutable (U811) were isolated from U81 cells. The authors are investigating by chromosome analysis and repair experiments why resistance to far-UV and mid-UV cell killing in these cells appears to be induced but the resulting survivors have a heterogeneous response to mutation induction by further doses of UV light

  12. Mechanism of systemic immune suppression by UV irradiation in vivo. II. The UV effects on number and morphology of epidermal Langerhans cells and UV-induced suppression of contact hypersensitivity have different wavelength dependencies

    The authors previously reported that broad band UV radiation or narrow bands of UV (Hbw 3 nm) of wavelengths 250 to 320 nm cause a systemic suppression of contact hypersensitivity (CHS) in mice, observed when the contact sensitizer is applied to a nonirradiated site. To determine if this effect is associated with UV-induced alterations in epidermal Langerhans cell (LC) numbers and morphology, they performed the following study. LC were identified by ATPase staining of EDTA-separated epidermal sheets. Electron microscopy studies confirmed that this method was a satisfactory indicator of the presence of LC. Mice were irradiated on the back with narrow band UV of peak wavelength 270, 290, or 320 nm. The irradiated skin was excised 24 hr later and was stained as described. They found that UV radiation of 270 or 290 nm caused (1) an alteration in LC morphology (loss of dendrites) and (2) a decrease in the total number of epidermal LC. Both effects occurred in a dose-dependent fashion. A dose of 320 nm UV that caused 50% systemic suppression of CHS had no effect on either the number or the morphology of LC at the site of irradiation. In addition, the number and morphology of LC were unaffected in the ventral epidermis (site of contact sensitization) of mice that had been previously irradiated on the back with a systemically suppressive dose of UV

  13. Segmentation of coronal features to understand the solar EUV and UV irradiance variability

    Kumara, S. T.; Kariyappa, R.; Zender, J. J.; Giono, G.; Delouille, V.; Chitta, L. P.; Damé, L.; Hochedez, J.-F.; Verbeeck, C.; Mampaey, B.; Doddamani, V. H.

    2014-01-01

    Context. The study of solar irradiance variability is of great importance in heliophysics, the Earth's climate, and space weather applications. These studies require careful identifying, tracking and monitoring of active regions (ARs), coronal holes (CHs), and the quiet Sun (QS). Aims: We studied the variability of solar irradiance for a period of two years (January 2011-December 2012) using the Large Yield Radiometer (LYRA), the Sun Watcher using APS and image Processing (SWAP) on board PROBA2, and the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). Methods: We used the spatial possibilistic clustering algorithm (SPoCA) to identify and segment coronal features from the EUV observations of AIA. The AIA segmentation maps were then applied on SWAP images, and parameters such as the intensity, fractional area, and contribution of ARs/CHs/QS features were computed and compared with the full-disk integrated intensity and LYRA irradiance measurements. Results: We report the results obtained from SDO/AIA and PROBA2/SWAP images taken from January 2011 to December 2012 and compare the resulting integrated full-disk intensity with PROBA2/LYRA irradiance. We determine the contributions of the segmented features to EUV and UV irradiance variations. The variations of the parameters resulting from the segmentation, namely the area, integrated intensity, and relative contribution to the solar irradiance, are compared with LYRA irradiance. We find that the active regions have a great impact on the irradiance fluctuations. In the EUV passbands considered in this study, the QS is the greatest contributor to the solar irradiance, with up to 63% of total intensity values. Active regions, on the other hand, contribute to about 10%, and off-limb structures to about 24%. We also find that the area of the features is highly variable suggesting that their area has to be taken into account in irradiance models, in addition to their intensity variations

  14. The total solar irradiance, UV emission and magnetic flux during the last solar cycle minimum

    Benevolenskaya, E E

    2013-01-01

    We have analyzed the total solar irradiance (TSI) and the spectral solar irradiance as ultraviolet emission (UV) in the wavelength range 115-180 nm, observed with the instruments TIM and SOLSTICE within the framework of SORCE (The Solar Radiation and Climate Experiment) during the long solar minimum between the 23rd and 24th cycles. The wavelet analysis reveals an increase in the magnetic flux in the latitudinal zone of the sunspot activity, accompanied with an increase in the TSI and UV on the surface rotation timescales of solar activity complexes. In-phase coherent structures between the mid-latitude magnetic flux and TSI/UV appear when the long-lived complexes of the solar activity are present. These complexes, which are related to long- lived sources of magnetic fields under the photosphere, are maintained by magnetic fluxes reappearing in the same longitudinal regions. During the deep solar minimum (the period of the absence of sunspots) a coherent structure has been found, in which the phase between th...

  15. Photostability study of commercial sunscreens submitted to artificial UV irradiation and/or fluorescent radiation.

    Romanhole, Rodrigo Colina; Ataide, Janaina Artem; Cefali, Leticia Caramori; Moriel, Patricia; Mazzola, Priscila Gava

    2016-09-01

    Sunscreens contain molecules with the ability to absorb and/or reflect UVA (ultraviolet A) and UVB (ultraviolet B) radiation, thereby preventing this radiation from reaching the epidermis or dermis. Their photo stabilities after exposure to UV radiation are well known and described, but there is little data on the stability of these filters after fluorescent indoors light radiation, such as from light emitted by commercial lamps present in homes and offices. Those lamps can expose people to varying levels of UVB, UVA, visible light, and IR (infrared). This study assesses the photostability of four different commercial products containing chemical sun filters after artificial UV and fluorescent irradiation, correlating the UVB and UVA absorption efficiencies of each product against the different types of radiation. The tested products were applied on a plate of polymethylmethacrylate (PMMA) and irradiated by a solar simulator with specific filters for UVA and UVB and a commercial fluorescent light source. According to the results, three formulations did not show photostability, suffering significant changes in their UV absorption spectra, and one of the selected formulations can be considered photostable. This reinforces the importance of conducting stability studies for sunscreen formulations in different conditions, including under artificial (indoor) light exposure. PMID:27341636

  16. Effect of moderate UV-B irradiation on Synechocystis PCC 6803 biliproteins

    In the present study, we investigated the mechanism of UV-B radiation induced damage to the light harvesting apparatus of the cyanobacterium Synechocystis 6803. Liquid chromatography analysis and spectroscopy investigations performed on phycobilisomes or isolated biliproteins irradiated with moderate UV-B intensity (1.3 W/m2) revealed rapid destruction of β-phycocyanin and a slower damage of the other biliproteins, α-phycocyanin and both α and β-allophycocyanin. EPR spin trapping measurements revealed that carbon centered adducts of the spin trap DMPO were formed. This evidence indicates that free radicals produced from bilins probably attack the polypeptide chain of protein inducing its degradation. Our results show that the bilin chromophore is the main target of UV-B irradiation, causing structural changes, which in turn induce reaction of the chromophore with atmospheric oxygen and lead to production of reactive radicals. Our results also demonstrate that β-phycocyanin is the most affected biliprotein, probably due to the presence of two bilins as chromophore

  17. Reversibility of U → F processes in X or UV irradiated KCl: H- systems

    Potassium Chloride crystals, pure, additively colored or hydrogenated have been exposed to X and UV radiations for correlation studies' of formation processes of defects. In hydrogenated samples, these irradiations are responsible-for a direct U→F centers conversion with the simultaneous creation of H2 molecules besides the intrinsic formation of F/hole centers. After prolonged irradiation, F aggregate centers react with H2 molecules forming U center pairs. As the two U centers have independent electronic transitions they add up, increasing the maximum height of the U band after F→U reversed reation. The saturation levels of defects produced by these two types of radiation are different because UV light also excites F centers while producing them. This effect is responsible by the F center aggregation and the inversion F→U decreasing the U→F efficiency. Crystals with F and U centers under F light also show F→U inversion but with higher efficiency than when under UV light. This F→U process gives back 90% of the initial U center concentration. This same F→U process was observed but at smaller rate of formation if samples containing U, F and F aggregates are left in the dark for prolonged periods of time. The same reactions take place namely H2 molecules annihilation F aggregates. (author)

  18. Post-irradiation kinetics of UV laser induced defects in silica

    We report an experimental study on post-irradiation kinetics of point defects generated in natural silica (a-SiO2) by UV photons (266 nm) of a Nd:YAG pulsed laser. Isothermal time dependencies of the UV-induced centers were investigated by electron spin resonance spectra recorded at different delays from the laser exposure. Our measurements evidenced two distinct processes active for some hours after the irradiation: the partial annealing of the E'γ centers (≡Si·) and the increase of the H(II) defects (≡Ge·-H). The results are discussed in the framework of the models concerning the diffusion and the recombination of atomic and molecular species occurring in the SiO2 matrix. New insights on both the reduction of Eγ' centers and the growth of H(II) centers are obtained, suggesting a crucial role of the diffusing molecular hydrogen in the structural changes of defects observed in the silica specimens after the UV laser exposure

  19. XANES Analysis of Organic Residues Produced from the UV Irradiation of Astrophysical Ice Analogs

    Nuevo, M.; Milam, S N.; Sandford, S A.; De Gregorio, B T.; Cody, G D.; Kilcoyne, A L.

    2011-01-01

    Organic residues formed in the laboratory from the ultraviolet (UV) photo-irradiation or ion bombardment of astrophysical ice analogs have been extensively studied for the last 15 years with a broad suite of techniques, including infrared (IR) and UV spectroscopies, as well as mass spectrometry. Analyses of these materials show that they consist of complex mixtures of organic compounds stable at room temperature, mostly soluble, that have not been fully characterized. However, the hydrolysis products of these residues have been partly identified using chromatography techniques, which indicate that they contain molecular precursors of prebiotic interest such as amino acids, nitrile-bearing compounds, and amphiphilic compounds. In this study, we present the first X-ray absorption near-edge structure (XANES) spectroscopy measurements of three organic residues made from the UV irradiation of ices having different starting compositions. XANES spectra confirm the presence of different chemical functions in these residues, and indicate that they are rich in nitrogenand oxygen-bearing species. These data can be compared with XANES measurements of extraterrestrial materials. Finally, this study also shows how soft X rays can alter the chemical composition of samples.

  20. Accuracy Assessments and Validation of an Expanded UV Irradiance Database from Satellite Total Ozone Mapping Spectrometer (TOMS)

    Krotkov, N. A.; Herman, J.; Fioletov, V.; Seftor, C.; Larko, D.; Vasilkov, A.

    2004-01-01

    The TOMS UV irradiance database (1978 to 2000) has been expanded to include 5 new products (noon irradiance at 305, 310, 324, and 380 nm, and noon erythemal-weighted irradiance), in addition to the existing erythemal daily exposure, which permit direct Comparisons with ground-based measurements from UV spectrometers. Sensitivity studies are conducted to estimate uncertainties of the new TOMS UV irradiance data due to algorithm apriori assumptions. Comparisons with Brewer spectrometers as well as filter radiometers are used to review of the sources of known errors. Inability to distinguish between snow and cloud cover using only TOMS data results in large errors in estimating surface UV using snow climatology. A correction is suggested for the case when the regional snow albedo is known from an independent source. The summer-time positive bias between TOMS UV estimations and Brewer measurements can be seen at all wavelengths. This suggests the difference is not related to ozone absorption effects. We emphasize that uncertainty of boundary layer UV aerosol absorption properties remains a major source of error in modeling UV irradiance in clear sky conditions. Neglecting aerosol absorption by the present TOMS algorithm results in a positive summertime bias in clear-sky UV estimations over many locations. Due to high aerosol variability the bias is strongly site dependent. Data from UV-shadow-band radiometer and well-calibrated CIMEL sun-sky radiometer are used to quantify the bias at NASA/GSFC site in Greenbelt, MD. Recommendations are given to enable potential users to better account for local conditions by combining standard TOMS UV data with ancillary ground measurements.

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

    Titanium dioxide was used as a photocatalyst to generate hydroxyl radicals in a flowthrough water reactor. Experiments were performed with cultures of Aeromonas hydrophila AWWX1 and Pseudomonas fluorescens R2f to evaluate the disinfection capabilities of the reactor. Although a decrease in viable counts was observed with long-wavelength (λ=370 nm) irradiated TiO2 pellets, direct UV254 irradiation seems a superior technology for the disinfection of transparent potable water since the viable counts of the test strains declined stronger (2-5 logs) and faster (20x) in UV254-treated water than in photoactivated TiO2-treated water. Outdoor tests conducted in the summer noonday sun showed that the viable counts of Aeromonas hydrophila AWWX1 decreased strongly (ca 5 log units) in transparent and turbid water samples (750 NTU) exposed to natural sunlight (47,000 lux). The addition of TiO2 to the solar irradiated waters did not influence the die-off of the strain. These observations indicate that the photocatalytic approach does not offer real prospects as an alternative technology for the disinfection of drinking water. (author)

  2. UV and global irradiance measurements and analysis during the Marsaxlokk (Malta) campaign

    Bilbao, J.; Román, R.; Yousif, C.; Mateos, D.; de Miguel, A.

    2015-07-01

    A solar radiation measurement campaign was performed in the south-eastern village of Marsaxlokk (35°50' N; 14°33' E; 10 m a.s.l), Malta, between 15 May and 15 October 2012. Erythemal solar radiation data (from a UVB-1 pyranometer), and total horizontal solar radiation (global and diffuse components) from two CM21 pyranometer were recorded. A comparison of atmospheric compounds from ground measurements and satellites shows that TOC (total ozone column) data from the Ozone Monitoring Instrument OMI, TOMS and DOAS algorithms correlate well with ground-based recorded data. The water vapour column and the aerosol optical depth at 550 nm show a significant correlation at the confidence level of 99 %. Parametric models for evaluating the solar UV erythemal (UVER), global (G) and diffuse (D) horizontal irradiances are calibrated, from which aerosol effects on solar irradiance are evaluated using the Aerosol Modification Factor (AMF). The AMFUVER values are lower than AMFG, indicating a greater aerosol effect on UVER than on global solar irradiance. In this campaign, several dust event trajectories are identified by means of the HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model and by synoptic conditions for characterizing desert dust events. Hence, changes in the UV index due to atmospheric aerosols are described.

  3. Checking for reversibility of aggregation of UV-irradiated glycogen phosphorylase b under crowding conditions.

    Eronina, Tatiana B; Mikhaylova, Valeriya V; Chebotareva, Natalia A; Makeeva, Valentina F; Kurganov, Boris I

    2016-05-01

    It is believed that the initial stages of protein aggregation are reversible and can be reversed by simple dilution, whereas prolonged exposure to factors responsible for denaturing proteins (for example, to elevated temperatures) results in the formation of irreversible aggregates. A new approach has been developed to discriminate the stage of the formation of reversible aggregates. Aggregation of UV-irradiated glycogen phosphorylase b (UV-Phb) was studied at 10, 25 and 37°C in the presence of crowders (polyethylene glycol and Ficoll-70) using dynamic light scattering and analytical ultracentrifugation (pH 6.8; 0.1M NaCl). The dilution of the protein solution in the course of aggregation at 10°C results in the breakdown of protein aggregates suggesting that the aggregation process is reversible. When aggregation of UV-Phb is studied at 37°C, reversibility is lacking. Chemical chaperones (arginine, proline) induce the breakdown of protein aggregates of UV-Phb formed at 10°C. In the experiments carried out at 37°C in the presence of crowder the addition of arginine results in disintegration of protein aggregates only at early stages of the aggregation process. It is assumed that general pathway of protein aggregation includes the formation of reversible, completely dissociable, partly dissociable and irreversible aggregates. PMID:26853826

  4. Photoprotective properties of the fluorescent europium complex in UV-irradiated skin.

    Vogt, O; Lademann, J; Rancan, F; Meinke, M C; Schanzer, S; Stockfleth, E; Sterry, W; Lange-Asschenfeldt, B

    2013-01-01

    In this study, we compared the UV-protective abilities of the europium complex compared to titanium dioxide, which represents the most common physical filter for ultraviolet light in the broad-band spectral range. The UV absorption and light transformative capacities of the europium complex were evaluated using a spectrometer with a double-integrating sphere showing that the europium complex does not only absorb and reflect UV light, but transforms it into red and infrared light. It was found that the europium complex binds to the surface of Jurkat cells in vitro. Cells incubated with the europium complex showed a significantly higher viability after UVA and UVB irradiation as compared to untreated cells and cells incubated with titanium dioxide pointing out its photoprotective properties. The europium complex and titanium dioxide show similar penetration capacities into the stratum corneum as tested in human and porcine skin using tape stripping analysis. The europium complex has proved to be an efficient UV filter with a low cyto- and phototoxic profile and therefore represents a potential candidate for use in sunscreen formulations. PMID:23306832

  5. Development of real time experimental system for investigating photochromic response to UV irradiation

    Photochemistry is a field of chemistry that deals with the chemical effects of light such as ultraviolet (UV), visible (Vis) or infrared (IR) radiation. Among many types of photochromic molecules, particular attentions have been given on spiropyrans because of their potential applications in industrial fields. Spiropyrans have the ability to change their chemical structure after exposed to a certain appropriate wavelength of light. However, spiropyrans are very sensitive dyes. For these reasons, an UV irradiation chamber was developed to control the surrounding environment which governs the external light intervention during photochromic work and when direct absorption measurement was performed. The chamber was then exploited to investigate the substituent effect on the absorption spectra of Benzo Indolino Pyrano Spiran (BIPS) dyes, 6-nitro BIPS and 8-ethoxy-6-nitro BIPS. Thus, our results suggest that the developed chamber was successfully utilized for photochromic system since it can protect the dyes from environmental intervention

  6. Incomplete excision repair process after UV-irradiation in MUT-mutants of Proteus mirabillis

    MUT-mutants of P. mirabilis seem to be able to perform the incision step in the course of excision repair. In contrast to the corresponding wildtype strains with MUT-mutants the number of single-strand breaks formed after UV-irradiation is independent of the UV-dose up to about 720 erg/mm2. Incubation in minimal medium over a longer time does not result in completion of excision repair; about 3-6 single-strand breaks in the DNA of these mutants remain open. Likewise, the low molecular weight of the newly synthesized daughter DNA confirms an incompletely proceeding or delayed repair process. As a possible reason for the mutator phenotype an alteration of the DNA-polymerase playing a role in excision and resynthesis steps of excision repair is discussed. (author)

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

    The functions of micronucleus (MI) were studied in the period of the sexual process in Paramecium caudatum-infusoria the descendants of the cells, whose micronucleus was locally irradiated with UV rays at the dose of 3060 erg/mm2. It has been found that the descendants of the irradiated cells (the cells of UV clones) can be involved into the sexual process irrespoctive of the morphological type of their MI. Four out of forteen UV clones have changed the initial mating type for the opposite one. It is suggested that the change of the mating type is related to the changes of MI genome resulted from UV irradiation. The pathway of nuclear transformations in the course of sexual process was traced in cells of three UV clones. It has been found, that local UV irradiation of MI causes a number of deviations in the behaviour of MI derivatives in the metagamic part of the sexual process in the clones, whose MI have undergone substantial morphological changes. The exconjugants produced by crossing of UV clones with such changed MI and the normal test-clone were characterized by low viability

  8. Adaptive alterations in the activities of scavengers of active oxygen in cucumber cotyledons irradiated with UV-B

    UV-B (290–320 nm) irradiation considerably reduced the cotyledon size of cucumber (Cucumis sativus L.) seedlings at 20 °C, and the extent of growth inhibition was reduced at 25 °C. At both temperatures, levels of endogenous scavengers and activities of active oxygen-scavenging enzymes were affected by UV-B irradiation. In particular, ascorbate peroxidase activity increased considerably, suggesting that active oxygen species might participate in the growth inhibition induced by UV-B irradiation. However, since no positive correlation was detected between the dependence of growth inhibition on temperature and the capacity to scavenge active species of oxygen, other mechanisms must be involved in the changes in the responses to UV-B that are related to temperature

  9. Changes of photosynthetic apparatus in single cells of Ankistrodesmus falcatus under normal the conditions and after UV irradiation

    The micro fluorometric method for evaluation of the state of photosynthetic apparatus of single cells through the chlorophyll variable fluorescence is described. The impact of the UV-light on the cells of the Ankistrodesmus falcatus alga by irradiation capacity of 150-1200 W/m2 and irradiation time up to 24 minutes is studied through the above method. Practical stability of the A. falcatus cell pigment apparatus by UV-irradiation remains unchanged, excluding the highest study dose, whereby partial destruction, of the photosynthetic pigments takes place

  10. European UV DataBase (EUVDB) as a repository and quality analyser for solar spectral UV irradiance monitored in Sodankylä

    Heikkilä, Anu; Kaurola, Jussi; Lakkala, Kaisa; Matti Karhu, Juha; Kyrö, Esko; Koskela, Tapani; Engelsen, Ola; Slaper, Harry; Seckmeyer, Gunther

    2016-08-01

    Databases gathering atmospheric data have great potential not only as data storages but also in serving as platforms for coherent quality assurance (QA). We report on the flagging system and QA tools designed for and implemented in the European UV DataBase (EUVDB; http://uv.fmi.fi/uvdb/" target="_blank">http://uv.fmi.fi/uvdb/) for measured data on solar spectral UV irradiance. We confine the study on the data measured by Brewer #037 MkII spectroradiometer in Sodankylä (67.37° N, 26.63° E) in 1990-2014. The quality indicators associated with the UV irradiance spectra uploaded into the database are retrieved from the database and subjected to a statistical analysis. The study demonstrates the performance of the QA tools of the EUVDB. In addition, it yields an overall view of the availability and quality of the solar UV spectra recorded in Sodankylä over a quarter of a century. Over 90 % of the four main quality indicators are flagged as GREEN, indicating the highest achievable quality. For the BLACK flags, denoting data not meeting the pre-defined requirements, the percentages for all the indicators remain below 0.12 %.

  11. Intrinsic Defects in UV-irradiated MgO Single Crystal Detected by Thermoluminescence

    D. Kadri

    2005-01-01

    Full Text Available The Thermoluminescence (TL properties of an MgO single crystal sample were studied from 170 to 500°K after UV-irradiation (4.8 eV for 10 min. The aim of this study was to determine the MgO intrinsic defects centers and in particular the F, F+, F2 and Fcat centers, these defects are localized in the 270-570 nm region, their TL signal was characterized by four emission bands detected at wavelengths 540, 380, 350 and 290 nm, respectively.

  12. Intrinsic Defects in UV-irradiated MgO Single Crystal Detected by Thermoluminescence

    D. Kadri; A. Mokeddem; Hamzaoui, S.

    2005-01-01

    The Thermoluminescence (TL) properties of an MgO single crystal sample were studied from 170 to 500°K after UV-irradiation (4.8 eV for 10 min). The aim of this study was to determine the MgO intrinsic defects centers and in particular the F, F+, F2 and Fcat centers, these defects are localized in the 270-570 nm region, their TL signal was characterized by four emission bands detected at wavelengths 540, 380, 350 and 290 nm, respectively.

  13. Extrinsic Defects in UV-irradiated MgO Single Crystal Detected by Thermoluminescence

    D. Kadri; S. Hiadsi; Hamzaoui, S.

    2007-01-01

    MgO single crystal sample previously irradiated with ultraviolet light (UV) 4.8 eV has been studied using thermoluminescence (TL) technique in the temperature range 170-500�K, in this study, we were mainly interested in the extrinsic defects (impurities), these impurities are localised in four distinct regions, Cr3+ is assigned to the first region 680-760 nm, in the second region 465-500 nm we find Ni2+, Fe3+ is localised in the third region 310-375 nm and lastly the Ca2+ and K+ have been fou...

  14. Extrinsic Defects in UV-irradiated MgO Single Crystal Detected by Thermoluminescence

    D. Kadri

    2007-01-01

    Full Text Available MgO single crystal sample previously irradiated with ultraviolet light (UV 4.8 eV has been studied using thermoluminescence (TL technique in the temperature range 170-500�K, in this study, we were mainly interested in the extrinsic defects (impurities, these impurities are localised in four distinct regions, Cr3+ is assigned to the first region 680-760 nm, in the second region 465-500 nm we find Ni2+, Fe3+ is localised in the third region 310-375 nm and lastly the Ca2+ and K+ have been found to emit in the 180-260 nm region.

  15. Swelling kinetics and stimuli-responsiveness of poly(DMAEMA) hydrogels prepared by UV-irradiation

    Swelling kinetics and responsive properties of poly(DMAEMA) hydrogels synthesized by UV-irradiation were studied. The swelling process in a phosphate and citrate buffer solution at 25 deg. C was found to be non-Fickian. As pH was increased, the swelling process would tend to be Fickian kinetics. The hydrogel proved to be pH-sensitive at about pH=3. Equilibrium swelling ratios would decrease with rising ionic strength. The hydrogel was thermosentive as well and the LCST in water is about 40 deg. C

  16. Pretreatment of whole blood using hydrogen peroxide and UV irradiation. Design of the advanced oxidation process

    Bragg, Stefanie A.; Armstrong, Kristie C.; Xue, Zi-Ling

    2012-01-01

    A new process to pretreat blood samples has been developed. This process combines the Advanced Oxidation Process (AOP) treatment (using H2O2 and UV irradiation) with acid deactivation of the enzyme catalase in blood. A four-cell reactor has been designed and built in house. The effect of pH on the AOP process has been investigated. The kinetics of the pretreatment process shows that at high CH2O2,t = 0, the reaction is zeroth order with respect to CH2O2 and first order with respect to Cblood....

  17. Effects of UV-irradiation on in vitro apatite-forming ability of TiO2 layers

    Titanium and its alloys are employed as artificial joints, bone plates, wires, screws and bone prostheses in orthopedic and dental fields, because of their high corrosion resistance, good mechanical properties, and biocompatibility. Since they cannot directly bond to living bone-tissue through stable chemical interactions, a few surface modification techniques have been proposed for giving materials apatite-forming ability that secures bone-tissue bonding, such as chemical treatment with H2O2 or NaOH, electrochemical oxidation, electrophoretic apatite particle deposition, and UV-irradiation of surface titanium oxide layer. This study examined how the combination of H2O2 chemical treatment and UV-irradiation affected in vitro apatite-formation on TiO2 (anatase phase) layers as UV was irradiated under a few different conditions. TiO2 layer was prepared by the chemical treatment with H2O2 solution and subsequent heat-treatment (CHT). CHT samples were irradiated with UV-light for 1 h in air or in ultra-pure water. They were then soaked in Kokubo's simulated body fluid (SBF; pH 7.4) at 36.5 deg. C for 1 day. Their surface structure and morphology were examined by using a thin film X-ray diffractometer (TF-XRD), and a scanning electron microscope (SEM). The UV-irradiation of CHT in air reduced the number of active sites for apatite nucleation. On the contrary, however, the UV-irradiation in water increased them. These opposite results indicate that environmental factors of the UV-irradiation are important for controlling the in vitro apatite-forming ability of anatase layer.

  18. Effects of UV-irradiation on in vitro apatite-forming ability of TiO{sub 2} layers

    Uetsuki, Keita, E-mail: dns20353@s.okayama-u.ac.jp [Graduate School of Natural Science and Technology, Okayama University, Tsushima, Kita-ku, Okayama-shi 700-8530 (Japan); Nakashima Medical Co., Ltd., Joto-Kitagata, Higashi-ku, Okayama-shi 709-0625 (Japan); Kaneda, Haruki [Faculty of Engineering, Okayama University, Tsushima, Kita-ku, Okayama-shi 700-8530 (Japan); Shirosaki, Yuki [Graduate School of Natural Science and Technology, Okayama University, Tsushima, Kita-ku, Okayama-shi 700-8530 (Japan); Hayakawa, Satoshi [Graduate School of Natural Science and Technology, Okayama University, Tsushima, Kita-ku, Okayama-shi 700-8530 (Japan); Research Center for Biomedical Engineering, Okayama University, Tsushima, Kita-ku, Okayama-shi 700-8530 (Japan); Osaka, Akiyoshi, E-mail: a-osaka@cc.okayama-u.ac.jp [Graduate School of Natural Science and Technology, Okayama University, Tsushima, Kita-ku, Okayama-shi 700-8530 (Japan); Research Center for Biomedical Engineering, Okayama University, Tsushima, Kita-ku, Okayama-shi 700-8530 (Japan)

    2010-10-15

    Titanium and its alloys are employed as artificial joints, bone plates, wires, screws and bone prostheses in orthopedic and dental fields, because of their high corrosion resistance, good mechanical properties, and biocompatibility. Since they cannot directly bond to living bone-tissue through stable chemical interactions, a few surface modification techniques have been proposed for giving materials apatite-forming ability that secures bone-tissue bonding, such as chemical treatment with H{sub 2}O{sub 2} or NaOH, electrochemical oxidation, electrophoretic apatite particle deposition, and UV-irradiation of surface titanium oxide layer. This study examined how the combination of H{sub 2}O{sub 2} chemical treatment and UV-irradiation affected in vitro apatite-formation on TiO{sub 2} (anatase phase) layers as UV was irradiated under a few different conditions. TiO{sub 2} layer was prepared by the chemical treatment with H{sub 2}O{sub 2} solution and subsequent heat-treatment (CHT). CHT samples were irradiated with UV-light for 1 h in air or in ultra-pure water. They were then soaked in Kokubo's simulated body fluid (SBF; pH 7.4) at 36.5 deg. C for 1 day. Their surface structure and morphology were examined by using a thin film X-ray diffractometer (TF-XRD), and a scanning electron microscope (SEM). The UV-irradiation of CHT in air reduced the number of active sites for apatite nucleation. On the contrary, however, the UV-irradiation in water increased them. These opposite results indicate that environmental factors of the UV-irradiation are important for controlling the in vitro apatite-forming ability of anatase layer.

  19. Global Mapping of Underwater UV Irradiances and DNA-Weighted Exposures using TOMS and SeaWiFS Data Products

    Vasilkov, Alexander; Krotkov, Nickolay; Herman, Jay; McClain, Charles; Arrigo, Kevin; Robinson, Wayne

    1999-01-01

    The global stratospheric ozone-layer depletion results In an increase in biologically harmful ultraviolet (UV) radiation reaching the surface and penetrating to ecologically significant depths in natural waters. Such an increase can be estimated on a global scale by combining satellite estimates of UV irradiance at the ocean surface from the Total Ozone Mapping Spectrometer (TOMS) satellite instrument with the SeaWIFS satellite ocean-color measurements in the visible spectral region. In this paper we propose a model of seawater optical properties in the UV spectral region based on the Case I water model in the visible range. The inputs to the model are standard monthly SeaWiFS products: chlorophyll concentration and the diffuse attenuation coefficient at 490nm. Penetration of solar UV radiation to different depths in open ocean waters is calculated using the RT (radiative transfer) quasi-single scattering approximation (QSSA). The accuracy of the QSSA approximation in the water is tested using more accurate codes. The sensitivity study of the underwater UV irradiance to atmospheric and oceanic optical properties have shown that the main environmental parameters controlling the absolute levels of the UVB (280-320nm) and DNA-weighted irradiance underwater are: solar-zenith angle, cloud transmittance, water optical properties, and total ozone. Weekly maps of underwater UV irradiance and DNA-weighted exposure are calculated using monthly-mean SeaWiFS chlorophyll and diffuse attenuation coefficient products, daily SeaWiFS cloud fraction data, and the TOMS-derived surface UV irradiance daily maps. The final products include global maps of weekly-average UVB irradiance and DNA-weighted daily exposures at 3m and 10m, and depths where the UVB irradiance and DNA-weighted dose rate at local noon are equal to 10% of their surface values.

  20. Gonadal differentiation in frogs, Rana japonica and R. brevipoda, raised from UV irradiated eggs

    The gonadal differentiation of anurans, Rana japonica and R. brevipoda, was examined in animals raised from eggs which had been irradiated at the vegetal hemisphere with UV (9300 erg/mm2) at the 2-cell stage. In R. japonica about 70% of the larvae at stage I from the pressed and UV-irradiated eggs were germ cell free, but at a stage immediately after metamorphosis all animals had at least some germ cells, although their gonads often were extremely small and poorly differentiated. When male animals matured sexually, many of them had abnormal gonads. However, all of them were shown by artificial means to be capable of fertilization. In the nonpressed and irradiated group, no larvae were germ cell free and the animals immediately after metamorphosis showed nearly normal gonadal differentiation except for the presence of a few degenerate oocytes in the ovaries. The results in R. brevipoda were basically similar to those in R. japonica. In both species, sex ratios were determined at two stages, the first immediately after metamorphosis and the other when the animals matured, as based on gonad morphology and histology and on external sexually dimorphic characters as well. Sex ratios at these two stages in frogs from the pressed and irradiated eggs differed markedly in R. brevipoda. The ratio was normal at metamorphosis but high M/F ratios occurred when animals became mature. That sex reversal took place in this species as well as in R. japonica (in which sex-ratio deviation was not statistically significant) was supported by the sex ratios of the progenies of these supernumerary males

  1. Gas chromatographic analysis of reactive carbonyl compounds formed from lipids upon UV-irradiation

    Peroxidation of lipids produces carbonyl compounds; some of these, e.g., malonaldehyde and 4-hydroxynonenal, are genotoxic because of their reactivity with biological nucleophiles. Analysis of the reactive carbonyl compounds is often difficult. The methylhydrazine method developed for malonaldehyde analysis was applied to simultaneously measure the products formed from linoleic acid, linolenic acid, arachidonic acid, and squalene upon ultraviolet-irradiation (UV-irradiation). The photoreaction products, saturated monocarbonyl, alpha,beta-unsaturated carbonyls, and beta-dicarbonyls, were derivatized with methylhydrazine to give hydrazones, pyrazolines, and pyrazoles, respectively. The derivatives were analyzed by gas chromatography and gas chromatography-mass spectrometry. Lipid peroxidation products identified included formaldehyde, acetaldehyde, acrolein, malonaldehyde, n-hexanal, and 4-hydroxy-2-nonenal. Malonaldehyde levels formed upon 4 hr of irradiation were 0.06 micrograms/mg from squalene, 2.4 micrograms/mg from linolenic acid, and 5.7 micrograms/mg from arachidonic acid. Significant levels of acrolein (2.5 micrograms/mg) and 4-hydroxy-2-nonenal (0.17 micrograms/mg) were also produced from arachidonic acid upon 4 hr irradiation

  2. Gas chromatographic analysis of reactive carbonyl compounds formed from lipids upon UV-irradiation

    Dennis, K.J.; Shibamoto, T. (Univ. of California, Davis (USA))

    1990-08-01

    Peroxidation of lipids produces carbonyl compounds; some of these, e.g., malonaldehyde and 4-hydroxynonenal, are genotoxic because of their reactivity with biological nucleophiles. Analysis of the reactive carbonyl compounds is often difficult. The methylhydrazine method developed for malonaldehyde analysis was applied to simultaneously measure the products formed from linoleic acid, linolenic acid, arachidonic acid, and squalene upon ultraviolet-irradiation (UV-irradiation). The photoreaction products, saturated monocarbonyl, alpha,beta-unsaturated carbonyls, and beta-dicarbonyls, were derivatized with methylhydrazine to give hydrazones, pyrazolines, and pyrazoles, respectively. The derivatives were analyzed by gas chromatography and gas chromatography-mass spectrometry. Lipid peroxidation products identified included formaldehyde, acetaldehyde, acrolein, malonaldehyde, n-hexanal, and 4-hydroxy-2-nonenal. Malonaldehyde levels formed upon 4 hr of irradiation were 0.06 micrograms/mg from squalene, 2.4 micrograms/mg from linolenic acid, and 5.7 micrograms/mg from arachidonic acid. Significant levels of acrolein (2.5 micrograms/mg) and 4-hydroxy-2-nonenal (0.17 micrograms/mg) were also produced from arachidonic acid upon 4 hr irradiation.

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

    The role of fullerene as a pro-oxidant or anti-oxidant in Ultraviolet B ray (UV-B)-induced disorders in mouse skin was investigated. Fullerene gave no photo-toxic effect to UV-B-irradiated mouse skin. Since erythema was concentrated at the pore circumference in a UV-B irradiation experiment in mouse skin, the sebaceous gland pairs was strongly implicated as a site for the generation of reactive oxygen species (ROS). In a histological evaluation of the skin stained with CH3MDFDA (ROS index) and YO-Pro-1 (apoptosis index), the fluorescence intensity of a sebaceous gland significantly increased with UV-B irradiation. With the application of fullerene to UV-irradiated mouse skin, no toxicity was recognized in comparison with the control, and erythema, the ROS index, and the apoptosis index decrease with the application of fullerene. Ascorbyl radical (AA·) increased with the application of ascorbate (AA) to UV-B-irradiated mouse skin, and AA· decreased with the application of fullerene. The co-application of AA and fullerene, which suppressed AA· in vitro, significantly suppressed erythema, and also suppressed both the ROS index and apoptosis index in mouse skin after UV-B irradiation. In both mouse skin at 48 h after UV-B irradiation and in an attempt to reproduce this phenomenon artificially in vitro, a similar high AA· peak (AA·/H· > 4) was observed in electron spin resonance (ESR) charts. The binding of fullerene with AA impairs the Fenton reaction between AA and Fe-protein based on the observation of ascorbate-specific UV absorption and a linear equation for the calibration curve. Therefore, fullerene may impair the intercalation of AA to a heme pocket by binding with AA. These results suggest that the co-application of AA and fullerene is effective against oxidative skin damage caused by UV-B irradiation, and the development of an AA· inhibitor such as fullerene should be useful for reducing organ damage associated with Fe-protein oxidation.

  4. Application of the Farr assay to the analysis of antibodies specific for UV irradiated DNA

    In order to determine the optimum conditions for reactivity in the ammonium sulphate precipitation (Farr) assay the authors have studied the DNA binding properties of two antibodies raised against ultraviolet single stranded DNA (UVssDNA) complexed with methylated bovine serum albumin. In general the buffer composition, pH, temperature, and ionic strength conditions described for binding to undamaged DNA were found to be appropriate for binding to UV-irradiated DNA. However, some differences in detail were noted which indicate the necessity for checking the physical conditions of binding of individual antibodies. Mouse monoclonal antibody and rabbit polyclonal antisera bound to UVssDNA very rapidly, even when DNA and ammonium sulphate were added simultaneously, whereas this procedure prevented binding of rabbit antisera to UV-irradiated double stranded DNA. Incubation at 450 C for 30 min inhibited binding by mouse antibody, and incubation at 370 C for 60 min caused reversible dissociation of the DNA-antibody complex. The optimised Farr assay was used to define the antigen specificities of the antibodies. (Auth.)

  5. The Oenothera plastome mutator: effect of UV irradiation and nitroso-methyl urea on mutation frequencies

    Oenothera plants homozygous for a recessive plastome mutator allele (pm) showed spontaneous mutation frequencies for plastome genes that are 200-fold higher than spontaneous levels. Mutations occurred at high frequencies in plants grown in the field, in a glasshouse, or as leaf tip cultures under fluorescent light, indicating that the plastome mutator activity is UV-independent. However, the chlorotic sectors became visible at an earlier stage of development when seedlings were irradiated, compared to seedlings that were not exposed to UV. These results imply that the rate of sorting-out was increased by the irradiation treatment, possibly due to a decrease in the effective number of multiplication-competent plastids, or a reduction in the extent of cytoplasmic mixing. Nitroso-methyl urea treatment of seeds had a dramatic effect on mutation frequency in both wild-type and plastome mutator samples. When the background mutation rates were low, the combination of the plastome mutator nucleus and the chemical mutagenesis treatment resulted in a synergistic effect, suggesting that the plastome mutator may involve a cpDNA repair pathway. (author)

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

    Highlights: ► In this paper, an original technique was present to improve the hydrophilic properties of polyester fibres. ► The modification of PET fabric was carried out using gaseous sulfur trioxide activated by UV irradiations. ► We fully characterized the modified and untreated fabrics. - Abstract: This paper describes an original technique aiming to improve the hydrophilic properties of polyester fibres. In this method, the sulfonation of the aromatic rings is carried out using gaseous sulfur trioxide activated by UV irradiations. Thus, exposing the polyester textile fabric to the UVC light (wavelength around 254 nm) under a stream of sulfur trioxide leads to the fixation of -SO3H groups. The amounts of the fixed sulfonate groups depended on the reaction conditions. Evidence of grafting deduced from the measurements of hygroscopic properties was carried out by contact angle measurement, moisture regain as well as by measuring the rate of retention. SEM and FT-IR analysis, DSC and DTA/TGA thermograms showed that no significant modifications have occurred in the bulk of the treated PET fabrics.

  7. Characterization of substances that restore impaired cell division of UV-irradiated E. coli B

    Substances which restore impaired cell division in UV-irradiated E. coli B were surveyed among various bacteria. The active substance was found only in several genera of Gram-negative bacteria, i.e., Escherichia, Enterobacter, Salmonella and some species of Pseudomonas. The activity in the dialyzed cell extract of E. coli B/r was observed in the presence of β-NAD and was enhanced by Mg2+ and Mn2+. The active substance was very labile, but the activity was protected by 1 mM dithiothreitol in the process of purification. The activity of a fraction recovered through DEAE-cellulose column chromatography was stimulated by the presence of membrane fraction. Upon treatment with lipid-degrading enzymes and proteases, the division-stimulating activity was lost or reduced. It appears that the inactivation by lipase and phospholipase A2 was due to the formation of lysophospholipids and that a proteinous substance participated in the recovery of impaired cell division of UV-irradiated E. coli B

  8. Formation of Nucleobases from the UV Photo-Irradiation of Pyrimidine in Astrophysical Ice Analogs

    Milam, S. N.; Nuevo, M.; Sandford, S. A.; Elsila, J. E.; Dworkin, J. P.

    2010-01-01

    Astrochemistry laboratory simulations have shown that complex organic molecules including compounds of astrobiological interest can be formed under interstellarl/circumstellar conditions from the vacuum UV irradiation of astrophysical ice analogs containing H2O, CO, CO2, CH3OH, NH13, etc. Of all prebiotic compounds, the formation of amino acids under such experimental conditions has been the most extensively studied. Although the presence of amino acids in the interstellar medium (ISM) has yet to be confirmed, they have been detected in meteorites, indicating that biomolecules and/or their precursors can be formed under extraterrestrial, abiotic conditions. Nucleobases, the building blocks of DNA and RNA, as well as other 1V-heterocycles, have also been detected in meteorites, but like amino acids, they have yet to be observed in the ISM. In this work, we present an experimental study of the formation of pyrimidine-based compounds from the UV photo-irradiation of pyrimidine in ice mixtures containing H2O, NH3, and/or CH3OH at low temperature and pressure.

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

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

    2012-10-01

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

  10. A novel solid state photocatalyst for living radical polymerization under UV irradiation

    Fu, Qiang; McKenzie, Thomas G.; Ren, Jing M.; Tan, Shereen; Nam, Eunhyung; Qiao, Greg G.

    2016-02-01

    This study presents the development of a novel solid state photocatalyst for the photoinduced controlled radical polymerization of methacrylates under mild UV irradiation (λmax ≈ 365 nm) in the absence of conventional photoinitiators, metal-catalysts or dye sensitizers. The photocatalyst design was based on our previous finding that organic amines can act in a synergistic photochemical reaction with thiocarbonylthio compounds to afford well controlled polymethacrylates under UV irradiation. Therefore, in the current contribution an amine-rich polymer was covalently grafted onto a solid substrate, thus creating a heterogeneous catalyst that would allow for facile removal, recovery and recyclability when employed for such photopolymerization reactions. Importantly, the polymethacrylates synthesized using the solid state photocatalyst (ssPC) show similarly excellent chemical and structural integrity as those catalysed by free amines. Moreover, the ssPC could be readily recovered and re-used, with multiple cycles of polymerization showing minimal effect on the integrity of the catalyst. Finally, the ssPC was employed in various photo-“click” reactions, permitting high yielding conjugations under photochemical control.

  11. Modification of immunological potential by ultraviolet radiation. I. Immune status of short-term uv-irradiated mice

    C3Hf/HeN mice support the progressive growth of most transplanted syngeneic ultraviolet (uv) light-induced tumors following short-term uv exposure whereas nonexposed mice reject these tumors. Because an immunosuppressive role in uv-mediated tumor susceptibility might be suggested by these observations, a comparison of several immunological parameters has been conducted. These include antibody production, proliferation in response to antigenic and mitogenic stimulation, and the generation of cytotoxic effector cells by normal or short-term uv-exposed mice. The results indicate that short-term uv irradiation of mice does not result in any readily detectable alterations of the host's immune system other than the consistent loss of the antitumor response mediating rejection of the transplanted uv-induced tumor

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

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

  13. UV laser irradiation of IR laser generated particles ablated from nitrobenzyl alcohol

    Particles generated by 2.94 μm pulsed IR laser ablation of liquid 3-nitrobenzyl alcohol were irradiated with a 351 nm UV laser 3.5 mm above and parallel to the sample target. The size and concentration of the ablated particles were measured with a light scattering particle sizer. The application of the UV laser resulted in a reduction in the average particle size by one-half and an increase in the total particle concentration by a factor of nine. The optimum delay between the IR and UV lasers was between 16 and 26 μs and was dependent on the fluence of the IR laser: higher fluence led to a more rapid appearance of particulate. The ejection velocity of the particle plume, as determined by the delay time corresponding to the maximum two-laser particle concentration signal, was 130 m/s at 1600 J/m2 IR laser fluence and increased to 220 m/s at 2700 J/m2. The emission of particles extended for several ms. The observations are consistent with a rapid phase change and emission of particulate, followed by an extended emission of particles ablated from the target surface.

  14. The influence of enhanced UV-B irradiation on the growth and composition of plants

    Barley (Hordeum vulgare), corn (Zea mays), bean (Phaseolus vulgaris), and radish (Raphanus Sativus) were irradiated under a lighting device for 5 to 10 days continuously at an increased UV-B fluence rate. These four species reacted differently to the elevated UV-radiation in their growth parameters, composition and leaf surface. Bean seedlings incurred the greatest damage, radish and barley seedlings less damage, and corn seedlings were hardly affected. The fresh weight, loaf area and chlorophyll, carstenoid and galactolipid contents were reduced in all species, whereas protein contents were increased throughout compared to controls. An approx. 50% increase in flavaroid content was noted in barley and radish seedlings. Studies on barley seedlings showed the effects on growth parameters and composition to be more market with increasing UV-B fluence rate. Fresh weights, chlorophyll and carotinoid contents were reduced proportionately, in contrast to flavaroid content which increased with increasing fluence rate to 180% of the control value. A bronze discolouration of the leaves appeared regularly at the highest fluence rate. (orig./AJ)

  15. Effect of UV irradiation on free radicals in synthetic melanin and melanin biopolymer from Sepia officinalis – EPR examination

    Zdybel Magdalena

    2015-07-01

    Full Text Available Free radicals in synthetic melanin and melanin from Sepia officinalis were studied by electron paramagnetic resonance (EPR spectroscopy. The effect of time of ultraviolet (UV irradiation on free radicals in these melanins was tested. The samples were exposed to UV during 15, 30, and 60 minutes. EPR spectra were measured with microwaves from an X-band (9.3 GHz in the range of microwave power of 2.2–70 mW. The performed EPR examinations indicate that high concentrations (~1021–1022 spin/g of o-semiquinone free radicals with g factors of 2.0039–2.0045 exist in all the tested samples. For nonirradiated samples, free radical concentration was higher in natural melanin than in synthetic melanin. UV irradiation caused the increase of free radical concentrations in synthetic melanin samples and this effect depends on the time of irradiation. The largest free radical formation in the both melanins was obtained for 60 min of UV irradiation. Free radical concentrations after the UV irradiation of melanins during 30 min were lower than during irradiation by 15 min, and probably this effect was the result of recombination of the radiatively formed free radicals. EPR lines of the tested samples broadened with increasing microwave power, so these lines were homogeneously broadened. The two types of melanins differed in the time of spin-lattice relaxation processes. Slower spin-lattice relaxation processes exist in melanin from Sepia officinalis than in synthetic melanin. UV irradiation did not change the time of spin-lattice relaxation processes in the tested melanins. The performed studies confirmed the usefulness of EPR spectroscopy in cosmetology and medicine.

  16. Process simulation and dynamic control for marine oily wastewater treatment using UV irradiation.

    Jing, Liang; Chen, Bing; Zhang, Baiyu; Li, Pu

    2015-09-15

    UV irradiation and advanced oxidation processes have been recently regarded as promising solutions in removing polycyclic aromatic hydrocarbons (PAHs) from marine oily wastewater. However, such treatment methods are generally not sufficiently understood in terms of reaction mechanisms, process simulation and process control. These deficiencies can drastically hinder their application in shipping and offshore petroleum industries which produce bilge/ballast water and produced water as the main streams of marine oily wastewater. In this study, the factorial design of experiment was carried out to investigate the degradation mechanism of a typical PAH, namely naphthalene, under UV irradiation in seawater. Based on the experimental results, a three-layer feed-forward artificial neural network simulation model was developed to simulate the treatment process and to forecast the removal performance. A simulation-based dynamic mixed integer nonlinear programming (SDMINP) approach was then proposed to intelligently control the treatment process by integrating the developed simulation model, genetic algorithm and multi-stage programming. The applicability and effectiveness of the developed approach were further tested though a case study. The experimental results showed that the influences of fluence rate and temperature on the removal of naphthalene were greater than those of salinity and initial concentration. The developed simulation model could well predict the UV-induced removal process under varying conditions. The case study suggested that the SDMINP approach, with the aid of the multi-stage control strategy, was able to significantly reduce treatment cost when comparing to the traditional single-stage process optimization. The developed approach and its concept/framework have high potential of applicability in other environmental fields where a treatment process is involved and experimentation and modeling are used for process simulation and control. PMID:26043376

  17. Disinfection of water and wastewater by UV-A and UV-C irradiation:application of real-time PCR method.

    Chatzisymeon, E.; Droumpali, A.; Mantzavinos, D.; Venieri, D.

    2011-01-01

    The disinfection efficiency of synthetic and real wastewater by means of UV-A and UV-C irradiation in the presence or absence of TiO(2) was investigated. A reference strain of Escherichia coli suspended in sterile 0.8% (w/v) NaCl aqueous solution was used as a synthetic wastewater, while real wastewater samples were collected from the outlet of the secondary treatment of a municipal wastewater treatment plant. E. coli inactivation was monitored both by the conventional culture technique and b...

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

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

    1983-08-01

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

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

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

  20. Bleaching of chlorophylls by UV irradiation in vitro: the effects on chlorophyll organization in acetone and n-hexane

    JELENA ZVEZDANOVIC; DEJAN MARKOVIC

    2008-01-01

    The stability of chlorophylls toward UV irradiation was studied by Vis spectrophotometry in extracts containing mixtures of photosynthetic pigments in acetone and n-hexane. The chlorophylls underwent destruction (bleaching) obeying first-order kinetics. The bleaching was governed by three major factors: the energy input of the UV photons, the concentration of the chlorophylls and the polarity of the solvent, implying different molecular organizations of the chlorophylls in the two solvents.

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

    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

  2. Electrochemical biosensing for dsDNA damage induced by PbSe quantum dots under UV irradiation

    Chuan

    2010-01-01

    An electrochemical sensor for the detection of the natural double-stranded DNA (dsDNA) damage induced by PbSe quantum dots (QDs) under UV irradiation was developed. The biosensing membranes were prepared by successively assembling 3-mercaptopropionic acid, polycationic poly (diallyldimethyl ammonium) and dsDNA on the surface of the gold electrode. Damage of dsDNA was fulfilled by immersing the sensing membrane electrode in PbSe QDs suspension and illuminating it with an UV lamp. Cyclic voltammetry was utilized to detect dsDNA damage with Co(phen)3+3 as the electroactive probe. The UV irradiation, Pb2+ ions liberated from the PbSe QDs under the UV irradiation and the reactive oxygen species (ROS) generated in the presence of the PbSe QDs also under the UV irradiation were the three factors of inducing the dsDNA damage. The synergistic effect of the three factors might dramatically enhance the damage of dsDNA. This electrochemical sensor provided a simple method for detecting DNA damage, and may be used for investigating the DNA damage induced by other QDs.

  3. Selective degradation of lignin and elimination of HO radicals in pulps by O3 and UV laser flash irradiation

    林鹿; 周贤涛; 邱玉桂

    2002-01-01

    HO radical is an aggressive reagent to abstract hydrogen from diverse substitutes and lead them to degradation, however, in reaction of active oxygen species with lignins, complex phenolic polymers, in dispersed lignocellulose such as pulp for environment-benign delignification, HO radicals should be eliminated as more as possible to prevent cellulose from unfavorably concomitant degradation. A reaction system of O3 is constructed under UV laser flash irradiation, and HO radicals are controlled efficiently by it. A new mechanism is proposed, for the first time, that O radicals generated from reaction of O3 with UV laser flash irradiation might be the contributor to scavenge HO radicals.

  4. Selective degradation of lignin and elimination of HO·radicals in pulps by O3 and UV laser flash irradiation

    林鹿; 周贤涛; 邱玉桂

    2002-01-01

    HO·radical is an aggressive reagent to abstract hydrogen from diverse substitutes and lead them to degradation, however, in reaction of active oxygen species with lignins, complex phenolic polymers, in dispersed lignocellulose such as pulp for environment-benign delignification, HO· radicals should be eliminated as more as possible to prevent cellulose from unfavorably concomitant degradation. A reaction system of O3 is constructed under UV laser flash irradiation, and HO·radicals are controlled efficiently by it. A new mechanism is proposed, for the first time, that O·radicals generated from reaction of O3 with UV laser flash irradiation might be the contributor to scavenge HO·radicals.

  5. Supported Zinc Oxide Photocatalyst for Decolorization and Mineralization of Orange G Dye Wastewater under UV365 Irradiation

    Ming-Chin Chang; Hung-Yee Shu; Tien-Hsin Tseng; Hsin-Wen Hsu

    2013-01-01

    To solve the environmental challenge of textile wastewater, a UV/ZnO photocatalytic system was proposed. The objective of this study was to prepare a photocatalytic system by utilizing both cold cathode fluorescent light (CCFL) UV irradiation and steel mesh supported ZnO nanoparticles in a closed reactor for the degradation of azo dye C.I. Orange G (OG). Various operating parameters such as reaction time, preparation temperature, mixing speed, ZnO dosage, UV intensity, pH, initial dye concent...

  6. Enhancement of the tolerance to oxidative stress in cucumber (Cucumis sativus L.) seedlings by UV-B irradiation: Possible involvement of phenolic compounds and antioxidative enzymes

    L.) seedlings were irradiated or not irradiated with UV-B for several days in environment-controlled growth chambers. The first leaves irradiated with UV-B were retarded in growth but simultaneously acquired a remarkably high tolerance to oxidative stress, as induced by paraquat treatment, compared with the non-irradiated leaves. This enhanced tolerance was observed within 1d after the start of UV-B irradiation and was maintained during the 12 d period of UV-B treatment. The effects of UV-B on several antioxidative enzymes were examined, and activities of superoxide dismutase, ascorbate peroxidase and guaiacol peroxidase, but not of glutathione reductase, were found to be enhanced. However, activation of these enzymes occurred only from 6 d after the start of irradiation. In contrast, accumulation of phenolic compounds was observed within 1d after the start of UV-B irradiation. HPLC analysis of phenolic compounds showed the distinct enhancement of a substance, which may have antioxidative properties in cucumber seedlings irradiated with UV-B. On the basis of these results, we conclude that not only antioxidative enzymes but also other factors in cucumber seedlings irradiated with UV-B, such as phenolic compounds, may participate in the enhanced tolerance to oxidative stress

  7. Polyester moulding - and coating materials to be hardened by UV-irradiation

    The invention deals with the use of a new type of photoinitiator (sensitizers) in known mixtures of unsaturated polyesters and polymerizing monomeric compounds to form moulding and coating masses which harden under UV irradiation. The photoinitiators chosen are compounds of the following formula: R1-CO-CR3R4-S-R2. R1 and R2 may be aromatic residues, R3 and R4 an aliphatic or araliphatic residue or a hydrogen atom. Another variant: R1 and R3 are aromatic residues, R2 and R4 aliphatic, araliphatic or aromatic residues. R4 may also be a hydrogen atom. The patent gives a large number of possible compounds. (UWI)

  8. Utilization of light water (DDW) as protective chemical in UV irradiation

    Bulbs of the onion variety Stoccardia were immersed for 30 minutes in control distilled water and in light water respectively. After immersing the bulbs were exposed to irradiation by a UV III-500 with 366 nm wavelength for 30 and 60 minutes. The bulbs were then planted and the vegetation period, size, weight and a shape indicator of the bulbs were followed up. A statistical calculation based on variance analysis showed that the light water present a protective effect, the values of the analyzed characteristics being higher than those of the control samples. The time necessary for bulbs to ripen increased in case of treatment with light water and also did the bulb weight

  9. The induction of mutation and recombination following UV irradiation during meiosis in Saccharomyces cerevisiae

    Irradiation of yeast cultures with ultraviolet light at discrete stages during meiosis produces cyclic variations in sensitivity, i.e. cells are more sensitive to the lethal effects of UV light prior to entry into the meiotic DNA synthesis, and this corresponds to a peak of induction of point mutation. Cells become more resistant to both induced point mutation and lethality as they enter meiotic DNA synthesis, but become more sensitive again during spore formation. The induced level of intragenic recombination rises during the period of commitment ot recombination to a level indistinguishable from the full meiotic level of spontaneous intragenic recombination. Induced reciprocal recombination remains above the spontaneous level up to the point of commitment to sporulation. (orig.)

  10. Reducing pathogens in combined sewer overflows using ozonation or UV irradiation.

    Tondera, Katharina; Klaer, Kassandra; Gebhardt, Jens; Wingender, Jost; Koch, Christoph; Horstkott, Marina; Strathmann, Martin; Jurzik, Lars; Hamza, Ibrahim Ahmed; Pinnekamp, Johannes

    2015-11-01

    Fecal contamination of water resources is a major public health concern in densely populated areas since these water bodies are used for drinking water production or recreational purposes. A main source of this contamination originates from combined sewer overflows (CSOs) in regions with combined sewer systems. Thus, the treatment of CSO discharges is urgent. In this study, we explored whether ozonation or UV irradiation can efficiently reduce pathogenic bacteria, viruses, and protozoan parasites in CSOs. Experiments were carried out in parallel settings at the outflow of a stormwater settling tank in the Ruhr area, Germany. The results showed that both techniques reduce most hygienically relevant bacteria, parasites and viruses. Under the conditions tested, ozonation yielded lower outflow values for the majority of the tested parameters. PMID:26431869

  11. Evolution of InP surfaces under low fluence pulsed UV irradiation

    Musaev, O.R. [Department of Physics, University of Missouri Kansas City, Rockhill Road 5100, Kansas City, MO 64110 (United States)], E-mail: musaevo@umkc.edu; Kwon, O.S.; Wrobel, J.M.; Zhu, D.-M.; Kruger, M.B. [Department of Physics, University of Missouri Kansas City, Rockhill Road 5100, Kansas City, MO 64110 (United States)

    2008-07-15

    An InP wafer was irradiated in air by a series of UV pulses from a nitrogen laser with fluences of 120 mJ/cm{sup 2} and 80 mJ/cm{sup 2}. These fluences are below the single-pulse ablation threshold of InP. Over the studied region the distribution of the radiation intensity was uniform. The number of pulses varied from 50 to 6000. The evolution of the surface morphology and structure was characterized by atomic force microscopy, optical microscopy and Raman spectroscopy. The relationship between mound size and the number of pulses starts out following a power law, but saturates for a sufficiently high number of pulses. The crossover point is a function of fluence. A similar relation exists for the surface roughness. Raman spectroscopic investigations showed little change in local crystalline structure of the processed surface layer.

  12. Aphidicolin inhibits repair of DNA in UV-irradiated human fibroblasts

    Aphidicolin, a specific inhibitor of DNA polymerase α, is shown to inhibit DNA repair in human diploid fibroblasts. Although aphidicolin has no apparent effect on the DNA of unirradiated cells, it causes a large number of strand breaks to accumulate in UV-irradiated cellular DNA. The number of breaks is the same as the number observed following a similar dose of ultraviolet light when cells are treated with arabinofuranosyl cytosine (araC) and hydroxyurea (HU), known inhibitors of repair. Moreover, two-dimensional paper chromatography shows that aphidicolin completely blocks removal of pyrimidine dimers. These observations are discussed in light of the proposed roles of DNA polymerases α and β in DNA replication and repair and the action of aphidicolin on polymerase α

  13. UV-Irradiated Photocatalytic Degradation of Nitrobenzene by Titania Binding on Quartz Tube

    Thou-Jen Whang

    2012-01-01

    Full Text Available A new method for UV-irradiated degradation of nitrobenzene by titania photocatalysts was proposed, titania nanoparticles were coated on a quartz tube through the introduction of tetraethyl orthosilicate into the matrix. The dependence of nitrobenzene photodegradation on pH, temperature, concentration, and air feeding was discussed, and the physical properties such as the activation energy, entropy, enthalpy, adsorption constant, and rate constant were acquired by conducting the reactions in a variety of experimental conditions. The optimum efficiency of the photodegradation with the nitrobenzene residue as low as 8.8% was achieved according to the experimental conditions indicated. The photodegradation pathways were also investigated through HPLC, GC/MS, ion chromatography (IC, and chemical oxygen demand (COD analyses.

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

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

    2012-10-01

    This paper describes an original technique aiming to improve the hydrophilic properties of polyester fibres. In this method, the sulfonation of the aromatic rings is carried out using gaseous sulfur trioxide activated by UV irradiations. Thus, exposing the polyester textile fabric to the UVC light (wavelength around 254 nm) under a stream of sulfur trioxide leads to the fixation of sbnd SO3H groups. The amounts of the fixed sulfonate groups depended on the reaction conditions. Evidence of grafting deduced from the measurements of hygroscopic properties was carried out by contact angle measurement, moisture regain as well as by measuring the rate of retention. SEM and FT-IR analysis, DSC and DTA/TGA thermograms showed that no significant modifications have occurred in the bulk of the treated PET fabrics.

  15. Nucleobases and Other Prebiotic Species from the UV Irradiation of Pyrimidine in Astrophysical Ices

    Sandford, Scott; Materese, Christopher; Nuevo, Michel

    2012-01-01

    Nucleobases are aromatic N-heterocycles that constitute the informational subunits of DNA and RNA and are divided into two families: pyrimidine bases (uracil, cytosine, and thymine) and purine bases (adenine and guanine). Nucleobases have been detected in meteorites and their extraterrestrial origin confirmed by isotope measurement. Although no N-heterocycles have been individually identified in the ISM, the 6.2-micron interstellar emission feature seen towards many astronomical objects suggests a population of such molecules is likely present. We report on a study of the formation of pyrimidine-based molecules, including nucleobases and other species of prebiotic interest, from the ultraviolet (UV) irradiation of pyrimidine in low temperature ices containing H2O, NH3, C3OH, and CH4, to simulate the astrophysical conditions under which prebiotic species may be formed in the Solar System.

  16. Intermediate fertile Triticum aestivum (+) Agropyron elongatum somatic hybrids are generated by low doses of UV irradiation

    Ai Xia CHENG; Guang Min XIA; Da Ying ZHI; Hui Min CHEN

    2004-01-01

    We report the production and characterization of somatic hybrids between Triticum aestivum L. and Agropyron elongatum (Host) Nevishi (the synonym is Thinopyrum ponticum). Asymmetric protoplast fusion was performed between Agropyron elongatum protoplasts irradiated with a low UV dose and protoplasts of wheat taken from nonregenerable suspension cultures. More than 40 green plantlets were obtained from 15 regenerated clones and one of them produced seeds. The phenotypes of the hybrid plants and seeds were intermediate between wheat and Agropyron elongatum. All of the regenerated calli and plants were verified as intergeneric hybrids on the basis of morphological observation and analysis of isozyme,cytological,5SrDNA spacer sequences and random amplified polymorphic DNA (RAPD). RFLP analysis of the mitochondrial genome revealed evidence of random segregation and recombination of mtDNA.

  17. Tailor-made dimensions of diblock copolymer truncated micelles on a solid by UV irradiation.

    Liou, Jiun-You; Sun, Ya-Sen

    2015-09-28

    We investigated the structural evolution of truncated micelles in ultrathin films of polystyrene-block-poly(2-vinylpyridine), PS-b-P2VP, of monolayer thickness on bare silicon substrates (SiOx/Si) upon UV irradiation in air- (UVIA) and nitrogen-rich (UVIN) environments. The structural evolution of micelles upon UV irradiation was monitored using GISAXS measurements in situ, while the surface morphology was probed using atomic force microscopy ex situ and the chemical composition using X-ray photoelectron spectroscopy (XPS). This work provides clear evidence for the interpretation of the relationship between the structural evolution and photochemical reactions in PS-b-P2VP truncated micelles upon UVIA and UVIN. Under UVIA treatment, photolysis and cross-linking reactions coexisted within the micelles; photolysis occurred mainly at the top of the micelles, whereas cross-linking occurred preferentially at the bottom. The shape and size of UVIA-treated truncated micelles were controlled predominantly by oxidative photolysis reactions, which depended on the concentration gradient of free radicals and oxygen along the micelle height. Because of an interplay between photolysis and photo-crosslinking, the scattering length densities (SLD) of PS and P2VP remained constant. In contrast, UVIN treatments enhanced the contrast in SLD between the PS shell and the P2VP core as cross-linking dominated over photolysis in the presence of nitrogen. The enhancement of the SLD contrast was due to the various degrees of cross-linking under UVIN for the PS and P2VP blocks. PMID:26251976

  18. Partial suppression by uv irradiation of the mechanism of resistance to cucumber mosaic virus in a resistant cucumber cultivar

    Shortwave uv (2540 A) significantly enhanced cucumber mosaic virus (CMV) multiplication in cotyledons of a resistant cucumber (Cucumis sativus L.) cultivar (Elem) when applied 1 to 3 days after inoculation. Compared with nonirradiated controls, infectivity increased 4 to 8 times when cotyledons were irradiated with dosages of 11,000 to 18,000 ergs mm-2 at a distance of 10 cm, 1 to 2 days after inoculation. Irradiations after longer intervals were less effective and irradiations with longwave uv (3600 A) had no effect. Irradiations before inoculation reduced extractable infectivity markedly. No difference in infectivity titer was obtained when cotyledons of a susceptible cucumber variety were irradiated. The number of virions, observed with an electron microscope, in extracts of cotyledons irradiated 48 hr after inoculation, was also significantly higher than in control extracts. The action spectrum for the suppression of the resistance (dose scale factor of 28 to 42) was between that of tobacco mosaic virus (TMV) (40 to 60) and that of TMV-RNA (15 to 20), used as biological dosimeters for nucleoproteins and nucleic acids, respectively, and differed markedly from that of a protein (4 to 5). It is suggested that the resistance mechanism is activated by the virus, and suppressed by shortwave uv, which probably blocks transcription by the formation of thymine dimers. (U.S.)

  19. Enhanced bioactivity of self-organized ZrO2 nanotube layer by annealing and UV irradiation

    Superhydrophilic ZrO2 nanotube layer was prepared by anodic oxidation of commercial pure Zr in aqueous solutions containing 1 M (NH4)2SO4 and 0.15 M NH4F. The effect of annealing and ultraviolet (UV) irradiation treatment on the microstructure, water contact angle and bioactivity of the ZrO2 nanotube layer was investigated. The as-anodized nanotube layer consists of cubic and amorphous ZrO2, no apatite crystals are deposited on its surface even after immersion in simulated body fluids (SBF) for 30 days, exhibiting weak apatite-inducing ability. After annealing at 450 deg. C for 3 h, the nanotube layer is composed of cubic and monoclinic ZrO2, and its apatite-forming ability is significantly enhanced because of its lattice structure matching that of apatite, apatite can be induced after immersion in SBF for 15 days. UV irradiation of the ZrO2 nanotube layers does not alter their surface morphologies and phase components, however, can improve the bioactivity only when the ZrO2 nanotube layer is well crystallized. The enhanced bioactivity by UV irradiation is thought to result from the abundant basic Zr-OH groups on the crystallized ZrO2 nanotube layer. Annealing and UV irradiation treatment do not alter the superhydrophilic nature of the ZrO2 nanotubes. - Research highlights: → Annealing treatment of the nanotube layer can significantly enhance its bioactivity. → UV irradiation immproves the bioactivity when ZrO2 nanotubes are well crystallized. → Annealing and UV treatment don't alter the superhydrophilicity of ZrO2 nanotubes.

  20. Global Increase in UV Irradiance during the Past 30 Years (1979-2008) Estimated from Satellite Data

    Herman, Jay R.

    2010-01-01

    Zonal average ultraviolet irradiance (flux ultraviolet, F(sub uv)) reaching the Earth's surface has significantly increased since 1979 at all latitudes except the equatorial zone. Changes are estimated in zonal average F(sub uv) caused by ozone and cloud plus aerosol reflectivity using an approach based on Beer's law for monochromatic and action spectrum weighted irradiances. For four different cases, it is shown that Beer's Law leads to a power law form similar to that applied to erythemal action spectrum weighted irradiances. Zonal and annual average increases in F(sub uv) were caused by decreases in ozone amount from 1979 to 1998. After 1998, midlatitude annual average ozone amounts and UV irradiance levels have been approximately constant. In the Southern Hemisphere, zonal and annual average UV increase is partially offset by tropospheric cloud and aerosol transmission decreases (hemispherical dimming), and to a lesser extent in the Northern Hemisphere. Ozone and 340 nm reflectivity changes have been obtained from multiple joined satellite time series from 1978 to 2008. The largest zonal average increases in F(sub uv) have occurred in the Southern Hemisphere. For clear-sky conditions at 50 S, zonal average F(sub uv) changes are estimated (305 nm, 23%; erythemal, 8.5%; 310 nm, 10%; vitamin D production, 12%). These are larger than at 50 N (305 nm, 9%; erythemal, 4%; 310 nm, 4%; vitamin D production, 6%). At the latitude of Buenos Aires, Argentina (34.6 S), the clear-sky Fuv increases are comparable to the increases near Washington, D. C. (38.9 N): 305 nm, 9% and 7%; erythemal, 6% and 4%; and vitamin D production, 7% and 5%, respectively.

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

    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.

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

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

    2012-01-01

    Nitrile incorporation into Titan aerosol accompanying hydrocarbon chemistry is thought to be driven by extreme UV wavelengths (lambda products. Our results show that aerosol formed from CH4/N2 photochemistry contains a surprising amount of nitrogen, up to 16% by mass, a result of photolysis in the far UV. The proportion of nitrogenated organics to hydrocarbon species is shown to be correlated with that of N2 in the irradiated gas. The aerosol mass greatly decreases when N2 is removed, indicating that N2 plays a major role in aerosol production. Because direct dissociation of N2 is highly improbable given the immeasurably low cross-section at the wavelengths studied, the chemical activation of N2 must occur via another pathway. Any chemical activation of N2 at wavelengths > 120 nm is presently unaccounted for in atmospheric photochemical models. We suggest that reaction with CH radicals produced from CH4 photolysis may provide a mechanism for incorporating N into the molecular structure of the aerosol. Further work is needed to understand the chemistry involved, as these processes may have significant implications for prebiotic chemistry on the early Earth and similar planets.

  3. Photolysis of phosphodiester bonds in plasmid DNA by high intensity UV laser irradiation

    The cleavage of phosphodiester bonds in DNA exposed to high intensity UV laser pulses in aerated aqueous solution has been investigated using a krypton fluoride excimer laser (248 nm) and bacterial plasmid DNA. The dependence of strand breakage on fluence and intensity has been studied in detail and shows that the process is non-linear with respect to intensity. The relationship between the quantum yield for strand breakage and intensity shows that the strand breakage reaction involves two-photon excitation of DNA bases. The quantum yield rises with intensity from a lower value of 7 x 10-5 until a maximum value of 4.5 x 10-4 is attained at intensities of 1011 W m-2 and above. This value is approximately fifty-fold higher than the quantum yield for strand breakage induced by exposure to low density UV irradiation (254 nm, 12 W m-2). DNA sequencing experiments have shown that strand breakage occurs by the specific cleavage of the phosphodiester bond which lies immediately 3' to guanine residues in the DNA, leaving some alkali-labile remnant attached to the terminal phosphate. A mechanism for DNA strand breakage which involves the generation of guanine radical cations is proposed. (author)

  4. Effect of UV irradiation (253.7 nm) on free Legionella and Legionella associated with its amoebae hosts.

    Cervero-Aragó, Sílvia; Sommer, Regina; Araujo, Rosa M

    2014-12-15

    Water systems are the primary reservoir for Legionella spp., where the bacteria live in association with other microorganisms, such as free-living amoebae. A wide range of disinfection treatments have been studied to control and prevent Legionella colonization but few of them were performed considering its relation with protozoa. In this study, the effectiveness of UV irradiation (253.7 nm) using low-pressure lamps was investigated as a disinfection method for Legionella and amoebae under controlled laboratory conditions. UV treatments were applied to 5 strains of Legionella spp., 4 strains of free-living amoeba of the genera Acanthamoeba and Vermamoeba, treating separately trophozoites and cysts, and to two different co-cultures of Legionella pneumophila with the Acanthamoeba strains. No significant differences in the UV inactivation behavior were observed among Legionella strains tested which were 3 logs reduced for fluences around 45 J/m(2). UV irradiation was less effective against free-living amoebae; which in some cases required up to 990 J/m(2) to obtain the same population reduction. UV treatment was more effective against trophozoites compared to cysts; moreover, inactivation patterns were clearly different between the genus Acanthamoeba and Vermamoeba. For the first time data about Vermamoeba vermiformis UV inactivation has been reported in a study. Finally, the results showed that the association of L. pneumophila with free-living amoebae decreases the effectiveness of UV irradiation against the bacteria in a range of 1.5-2 fold. That fact demonstrates that the relations established between different microorganisms in the water systems can modify the effectiveness of the UV treatments applied. PMID:25306486

  5. Ultraviolet Light (UV) Inactivation of Porcine Parvovirus in Liquid Plasma and Effect of UV Irradiated Spray Dried Porcine Plasma on Performance of Weaned Pigs.

    Polo, Javier; Rodríguez, Carmen; Ródenas, Jesús; Russell, Louis E; Campbell, Joy M; Crenshaw, Joe D; Torrallardona, David; Pujols, Joan

    2015-01-01

    A novel ultraviolet light irradiation (UV-C, 254 nm) process was designed as an additional safety feature for manufacturing of spray dried porcine plasma (SDPP). In Exp. 1, three 10-L batches of bovine plasma were inoculated with 10(5.2 ± 0.12) tissue culture infectious dose 50 (TCID50) of porcine parvovirus (PPV) per mL of plasma and subjected to UV-C ranging from 0 to 9180 J/L. No viable PPV was detected in bovine plasma by micro-titer assay in SK6 cell culture after UV-C at 2295 J/L. In Exp. 2, porcine plasma was subjected to UV-C (3672 J/L), then spray dried and mixed in complete mash diets. Diets were a control without SDPP (Control), UV-C SDPP either at 3% (UVSDPP3) or 6% (UVSDPP6) and non-UV-C SDPP at 3% (SDPP3) or 6% (SDPP6). Diets were fed ad libitum to 320 weaned pigs (26 d of age; 16 pens/diet; 4 pigs/pen) for 14 d after weaning and a common diet was fed d 15 to 28. During d 0 to 14, pigs fed UVSDPP3, UVSDPP6, or SDPP6 had higher (P < 0.05) weight gain and feed intake than control. During d 0 to 28, pigs fed UVSDPP3 and UVSDPP6 had higher (P < 0.05) weight gain and feed intake than control and SDPP3, and SDPP6 had higher (P < 0.05) feed intake than control. Also, pigs fed UVSDPP had higher (P < 0.05) weight gain than pigs fed SDPP. In conclusion, UV-C inactivated PPV in liquid plasma and UVSDPP used in pig feed had no detrimental effects on pig performance. PMID:26171968

  6. Ultraviolet Light (UV Inactivation of Porcine Parvovirus in Liquid Plasma and Effect of UV Irradiated Spray Dried Porcine Plasma on Performance of Weaned Pigs.

    Javier Polo

    Full Text Available A novel ultraviolet light irradiation (UV-C, 254 nm process was designed as an additional safety feature for manufacturing of spray dried porcine plasma (SDPP. In Exp. 1, three 10-L batches of bovine plasma were inoculated with 10(5.2 ± 0.12 tissue culture infectious dose 50 (TCID50 of porcine parvovirus (PPV per mL of plasma and subjected to UV-C ranging from 0 to 9180 J/L. No viable PPV was detected in bovine plasma by micro-titer assay in SK6 cell culture after UV-C at 2295 J/L. In Exp. 2, porcine plasma was subjected to UV-C (3672 J/L, then spray dried and mixed in complete mash diets. Diets were a control without SDPP (Control, UV-C SDPP either at 3% (UVSDPP3 or 6% (UVSDPP6 and non-UV-C SDPP at 3% (SDPP3 or 6% (SDPP6. Diets were fed ad libitum to 320 weaned pigs (26 d of age; 16 pens/diet; 4 pigs/pen for 14 d after weaning and a common diet was fed d 15 to 28. During d 0 to 14, pigs fed UVSDPP3, UVSDPP6, or SDPP6 had higher (P < 0.05 weight gain and feed intake than control. During d 0 to 28, pigs fed UVSDPP3 and UVSDPP6 had higher (P < 0.05 weight gain and feed intake than control and SDPP3, and SDPP6 had higher (P < 0.05 feed intake than control. Also, pigs fed UVSDPP had higher (P < 0.05 weight gain than pigs fed SDPP. In conclusion, UV-C inactivated PPV in liquid plasma and UVSDPP used in pig feed had no detrimental effects on pig performance.

  7. Preparation and Application of Titanate Nanotubes on Dye Degradation from Aqueous Media by UV Irradiation

    Rui Liu

    2015-01-01

    Full Text Available Titanate nanotubes were synthesized by a hydrothermal method using commercial TiO2 powder and then used as a photocatalyst. The titanate nanotubes were synthesized by varying the hydrothermal temperature from 110°C to 180°C. The morphological changes and phase transformation of the TiO2 nanotubes were analyzed by X-ray diffraction (XRD, scanning electron microscopy (SEM, and transmission electron microscopy (TEM. The particles’ scattering behavior was investigated by Raman studies, and the surface area of the nanotubes was determined by a Brunauer, Emmett, and Teller (BET analysis. Comparative studies show that the surface area of nanotubes increases with increasing temperature up to 130°C. The catalytic behavior of the synthesized nanotubes was also studied. The as-prepared titanate nanotubes were applied to methylene blue (MB, an organic dye degradation in aqueous media by UV irradiation. Approximately 99% of the dye was removed from the aqueous media using 2 g/L titanate nanotube when the initial dye concentration was 9 mg/L. The total irradiation time was 2 h.

  8. The effects of hyaluronan and its fragments on lipid models exposed to UV irradiation.

    Trommer, Hagen; Wartewig, Siegfried; Böttcher, Rolf; Pöppl, Andreas; Hoentsch, Joachim; Ozegowski, Jörg H; Neubert, Reinhard H H

    2003-03-26

    The effects of hyaluronan and its degradation products on irradiation-induced lipid peroxidation were investigated. Liposomal skin lipid models with increasing complexity were used. Hyaluronan and its fragments were able to reduce the amount of lipid peroxidation secondary products quantified by the thiobarbituric acid (TBA) assay. The qualitative changes were studied by mass spectrometry. To elucidate the nature of free radical involvement electron paramagnetic resonance (EPR) studies were carried out. The influence of hyaluronan and its fragments on the concentration of hydroxyl radicals generated by the Fenton system was examined using the spin trapping technique. Moreover, the mucopolysaccharide's ability to react with stable radicals was checked. The quantification assay of 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH) showed no concentration changes of the stable radical caused by hyaluronan. Hyaluronan was found to exhibit prooxidative effects in the Fenton assay in a concentration dependent manner. A transition metal chelation was proposed as a mechanism of this behavior. Considering human skin and its constant exposure to UV light and oxygen and an increased pool of iron in irradiated skin the administration of hyaluronan or its fragments in cosmetic formulations or sunscreens could be helpful for the protection of the human skin. PMID:12623198

  9. A novel estrogenic compound transformed from fenthion under UV-A irradiation

    Yamada, Kenta, E-mail: p7404@mail.u-shizuoka-ken.ac.jp [Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1, Yada, Suruga-ku, Shizuoka 422-8526 (Japan); Terasaki, Masanori, E-mail: terasaki@u-shizuoka-ken.ac.jp [Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1, Yada, Suruga-ku, Shizuoka 422-8526 (Japan); Makino, Masakazu, E-mail: makinom@u-shizuoka-ken.ac.jp [Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, 52-1, Yada, Suruga-ku, Shizuoka 422-8526 (Japan)

    2010-04-15

    The photo-transformed products of fenthion well-known as one of the most photosensitive organophosphorus insecticides and their estrogenic activities were investigated using a yeast two-hybrid assay incorporating the human estrogen receptor {alpha} (hER{alpha}). We identified fenthion sulfoxide and 3-methyl-4-methylsulfinylphenol (MMS) as the major transformed products and 3-methyl-4-(methylthio)phenol (MMP) as the minor product under UV-A irradiation. Further, significant estrogenic activity was observed in the solution irradiated for 160 min; this activity was evaluated as 18 pM converted to 17{beta}-estradiol (E{sub 2}) equivalent concentration. By using authentic standards, it was found that MMP possessed weak estrogenic activity; its activity was evaluated as 1.7 x 10{sup -6} times compared with that of E{sub 2}. However, it was also revealed that the activity due to MMP was only 13%. From high-performance liquid chromatography (HPLC) and nuclear magnetic resonance (NMR) spectroscopies, we newly identified a significant estrogenic compound transformed from fenthion, O,O-dimethyl S-[3-methyl-4-(methylthio)phenyl]phosphorothioate, S-aryl fenthion.

  10. Elimination of pharmaceutical residues in biologically pre-treated hospital wastewater using advanced UV irradiation technology: A comparative assessment

    Koehler, C., E-mail: christian.koehler@tudor.lu [Public Research Centre Henri Tudor/Resource Centre for Environmental Technologies, 66 rue de Luxembourg, BP 144, L-4002 Esch-sur-Alzette (Luxembourg); Venditti, S.; Igos, E.; Klepiszewski, K.; Benetto, E.; Cornelissen, A. [Public Research Centre Henri Tudor/Resource Centre for Environmental Technologies, 66 rue de Luxembourg, BP 144, L-4002 Esch-sur-Alzette (Luxembourg)

    2012-11-15

    UV irradiation technology as a membrane bioreactor (MBR) post-treatment was investigated and assessed. Both UV low pressure (LP) and medium pressure (MP) lamps were examined. The technology was installed in a pilot plant treating hospital wastewater to provide the study with adequate field data. The effect of the UV irradiation was enhanced with varying dosages of H{sub 2}O{sub 2} to establish an advanced oxidation process (AOP). The efficiency of the pharmaceutical removal process was assessed by examining 14 micropollutants (antibiotics, analgesics, anticonvulsants, beta-blockers, cytostatics and X-ray contrast media) which are typically released by hospitals and detected with liquid chromatography coupled tandem mass spectrometry (LC-MS/MS). While the MBR treatment generally showed only a low degradation capacity for persistent pharmaceuticals, much better degradation was obtained by applying UV irradiation and H{sub 2}O{sub 2} as AOP. The 'conventional' cost-benefit analysis of the different technology options taking into account both electrical energy consumption and pharmaceutical removal efficiency, revealed clearly better performance of low pressure UV lamps as AOP. However, a holistic comparison between the different scenarios was carried out by evaluating their environmental impacts using the life cycle assessment (LCA) methodology. Decisive advantages were highlighted to include this approach in the decision making process.

  11. Elimination of pharmaceutical residues in biologically pre-treated hospital wastewater using advanced UV irradiation technology: A comparative assessment

    UV irradiation technology as a membrane bioreactor (MBR) post-treatment was investigated and assessed. Both UV low pressure (LP) and medium pressure (MP) lamps were examined. The technology was installed in a pilot plant treating hospital wastewater to provide the study with adequate field data. The effect of the UV irradiation was enhanced with varying dosages of H2O2 to establish an advanced oxidation process (AOP). The efficiency of the pharmaceutical removal process was assessed by examining 14 micropollutants (antibiotics, analgesics, anticonvulsants, beta-blockers, cytostatics and X-ray contrast media) which are typically released by hospitals and detected with liquid chromatography coupled tandem mass spectrometry (LC–MS/MS). While the MBR treatment generally showed only a low degradation capacity for persistent pharmaceuticals, much better degradation was obtained by applying UV irradiation and H2O2 as AOP. The “conventional” cost-benefit analysis of the different technology options taking into account both electrical energy consumption and pharmaceutical removal efficiency, revealed clearly better performance of low pressure UV lamps as AOP. However, a holistic comparison between the different scenarios was carried out by evaluating their environmental impacts using the life cycle assessment (LCA) methodology. Decisive advantages were highlighted to include this approach in the decision making process.

  12. Mitochondrial and glycolytic activity of UV-irradiated human keratinocytes and its stimulation by a Saccharomyces cerevisiae autolysate.

    Schütz, Rolf; Kuratli, Karin; Richard, Nathalie; Stoll, Clarissa; Schwager, Joseph

    2016-06-01

    Cutaneous aging is correlated with mitochondrial dysfunction and a concomitant decline in energy metabolism that can be accelerated by extrinsic factors such as UV radiation (UVR). In this study we compared cellular bioenergetics of normal and UV-irradiated primary human epidermal keratinocytes. Moreover, we investigated the influence of a Saccharomyces cerevisiae autolysate (SCA) on stressed keratinocytes to regain cellular homeostasis. Cellular metabolism was assessed by extracellular flux analysis which measures oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) as well as by ATP quantification. The expression level of ten mitochondria related genes in normal and UVR-stimulated (60mJ/cm(2) UVB) keratinocytes was quantified by real-time PCR and the impact of SCA addition was determined. Sublethal UV stress increased mitochondrial dysfunction in keratinocytes which resulted in reduced viability, uncoupled oxidative phosphorylation, and down-regulated mitochondrial gene expression. Particularly, gene expression of SHDA, UPC2, BID, and ATP5A1 was reduced about twofold within 4h. Treatment of keratinocytes with SCA shifted cellular metabolism towards a more energetic status by increasing the respiratory rate and glycolysis. SCA also stimulated cellular ATP production after short (4h) and prolonged (22h) incubations and induced the expression of genes related to mitochondrial function towards normal expression levels upon UV irradiation. The decreased respiratory capacity of UV-irradiated keratinocytes was partially compensated by the addition of SCA which enhanced glycolytic activity and thereby increased cellular resistance to environmental stress. PMID:27060217

  13. Elimination of pharmaceutical residues in biologically pre-treated hospital wastewater using advanced UV irradiation technology: a comparative assessment.

    Köhler, C; Venditti, S; Igos, E; Klepiszewski, K; Benetto, E; Cornelissen, A

    2012-11-15

    UV irradiation technology as a membrane bioreactor (MBR) post-treatment was investigated and assessed. Both UV low pressure (LP) and medium pressure (MP) lamps were examined. The technology was installed in a pilot plant treating hospital wastewater to provide the study with adequate field data. The effect of the UV irradiation was enhanced with varying dosages of H2O2 to establish an advanced oxidation process (AOP). The efficiency of the pharmaceutical removal process was assessed by examining 14 micropollutants (antibiotics, analgesics, anticonvulsants, beta-blockers, cytostatics and X-ray contrast media) which are typically released by hospitals and detected with liquid chromatography coupled tandem mass spectrometry (LC-MS/MS). While the MBR treatment generally showed only a low degradation capacity for persistent pharmaceuticals, much better degradation was obtained by applying UV irradiation and H2O2 as AOP. The "conventional" cost-benefit analysis of the different technology options taking into account both electrical energy consumption and pharmaceutical removal efficiency, revealed clearly better performance of low pressure UV lamps as AOP. However, a holistic comparison between the different scenarios was carried out by evaluating their environmental impacts using the life cycle assessment (LCA) methodology. Decisive advantages were highlighted to include this approach in the decision making process. PMID:22748974

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

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

  15. Contribution of a caffeine-sensitive recombinational repair pathway to survival and mutagenesis in UV-irradiated Schizosaccharomyces pombe

    Cells of wild-type Schizosacharomyces pombe exposed to UV radiation in either G1 or G2 phase show enhanced inactivation of colony-forming ability if plated in the presence of caffeine. This UV-sensitization by caffeine is abolished in both G1 an G2 phase cells by the radlmutation; since both caffeine and the radl mutation markedly reduce recombinational events, this suggests that a recombinational repair process is active in cells irradiated either in G1 or G2 phase. Caffeine-sensitive repair begins immediately and is completed before resumption of DNA synthesis. Caffeine-sensitive repair of UV-damage in G1 cells displays a considerable lag and then occurs concomitantly with DNA synthesis. UV-induced mutagenesis was examined in wild-type and rad mutants using a forward mutation system. Rad mutants which show higher UV-induced mutation rates than wild-type retain the recombinational mechanism. In contrast, rad strains which are relatively UV-immutable compared to wild-type do not possess the caffeine-sensitive UV-repair process. The recombinational process therefore may be the major pathway responsible for UV-induced mutation. (orig./AJ)

  16. Growth analysis of UV-B-irradiated cucumber seedlings as influenced by photosynthetic photon flux source and cultivar

    A growth analysis was made of ultraviolet-B (UV-B)-sensitive (Poinsett) and insensitive (Ashley) cultivars of Cucuumis satives L. grown in growth chambers at 600 μmol m−2 s−1 of photosynthetic photon flux (PPF) provided by red- and far-red-deficient metal halide (MH) or blue- and UV-A-deficient high pressure sodium/deluxe f HPS/DX) lamps. Plants were irradiated 6 h daily with 0.2 f-UV-B) or 18.2 C+UV-B) kJ m−2 day−1 of biologically effective UV-B for 8 or 15 days from time of seeding. In general, plants given supplemental UV-B for 15 days showed lower leaf area ratio (LARs, and higher specific leaf mass (SLM) mean relative growth rate (MRGR) and net assimilation rate (NAR) than that of control plants, but they showed no difference in leaf mass ratio (LMR), Plants grown under HPS/DX lamps vs MH lamps showed higher SLM and NAR. lower LAR and LMR. hut no difference in MRGR. LMR was the only growth parameter affected by cultivar: at 15 days, it was slightly greater in Poinsett than in Ashley. There were no interactive effects of UV-B. PPF source or cultivar on any of the growth parameters determined, indicating that the choice of either HPS/DX or MH lamps should not affect growth response to UV-B radiation. This was true even though leaves of UV-B-irradiated plants grown under HPS/DX lamps have been shown to have greater chlorosis than those grown under MH lamps. (author)

  17. Role of bacterial and phage recombination systems and of DNA replication in genetic recombination of UV-irradiated phage lambda

    A study was made in E. coli K12 of the influence of the bacterial Rec and phage lambda Red recombination systems on the rescue of the 0+ gene from the prophage by a superinfecting 0- phage, UV irradiated or not. In the absence of UV irradiation the Red system produces more recombinants than does the Rec system, and its action requires DNA replication. The presence of UV lesions in the lambda DNA facilitates the action of the Rec system, which is more efficient in this instance than the Red system and can act in the absence of DNA replication. In all cases, there is a cooperation between the two generalized recombination systems. (orig.)

  18. Bactericidal, structural and morphological properties of ZnO2 nanoparticles synthesized under UV or ultrasound irradiation

    Colonia, R.; Solís, J. L.; Gómez, M.

    2014-03-01

    Nanoparticles of ZnO2 were synthesized by a sol-gel method using Zn(CH3COO)2 and H2O2 in an aqueous solution exposed to either ultraviolet (UV) or ultrasound irradiation. X-ray diffraction and scanning electron microscopy showed that the nanostructures consisted of spherical blackberry-like clusters. Nanoparticles fabricated by using UV irradiation had smaller sizes and narrower size distributions than nanoparticles prepared by using ultrasound. Bacillus subtilis (B. subtilis), Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were used as test microorganisms, and the antibacterial activity of the ZnO2 nanoparticles was studied by use of the well diffusion agar bacteriological test. ZnO2 nanoparticles synthetized using UV had the best antibacterial properties. The inhibition zone was largest for B. subtilis but was present also for S. aureus and E. coli.

  19. Bactericidal, structural and morphological properties of ZnO2 nanoparticles synthesized under UV or ultrasound irradiation

    Nanoparticles of ZnO2 were synthesized by a sol–gel method using Zn(CH3COO)2 and H2O2 in an aqueous solution exposed to either ultraviolet (UV) or ultrasound irradiation. X-ray diffraction and scanning electron microscopy showed that the nanostructures consisted of spherical blackberry-like clusters. Nanoparticles fabricated by using UV irradiation had smaller sizes and narrower size distributions than nanoparticles prepared by using ultrasound. Bacillus subtilis (B. subtilis), Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were used as test microorganisms, and the antibacterial activity of the ZnO2 nanoparticles was studied by use of the well diffusion agar bacteriological test. ZnO2 nanoparticles synthetized using UV had the best antibacterial properties. The inhibition zone was largest for B. subtilis but was present also for S. aureus and E. coli. (paper)

  20. Genetic recombination of Herpes simplex virus, the role of the host cell and UV-irradiation of the virus

    Recombination frequencies for two sets of genetic markers of Herpes simplex virus were determined in various host cells with and without ultraviolet irradiation of the virus. UV irradiation increased the recombination frequency in all the cell types studied in direct proportion to the unrepaired lethal damage. In human skin fibroblasts derived from a patient with xeroderma pigmentosum (XP) of complementation group A, a given dose of UV stimulated recombination more than that in fibroblasts from normal individuals. On the other hand, UV stimulation of HSV recombination was slightly less than normal in fibroblasts derived from a patient with a variant form XP and from an ataxia telangiectasia patient. Caffeine, an agent known to inhibit repair of UV damage, reduced recombination in most of the cell types studied but did not suppress the UV-induced increase in recombination. These findings suggest that for virus DNA with the same number of unrepaired UV-lesions, each of the tested cell types promoted HSV-recombination to an equivalent extent. (orig.)

  1. Estimating cloud optical thickness and associated surface UV irradiance from SEVIRI by implementing a semi-analytical cloud retrieval algorithm

    P. Pandey

    2012-01-01

    Full Text Available In this paper, we describe the implementation of the Semi-Analytical Cloud Retrieval Algorithm (SACURA, to obtain scaled cloud optical thickness (SCOT from satellite imagery acquired with the SEVIRI instrument and surface UV irradiance levels. In estimation of SCOT particular care is given to the proper specification of the background (i.e., cloud-free spectral albedo and the retrieval of the cloud water phase from reflectance ratios in SEVIRI's 0.6 μm and 1.6 μm spectral bands. The SACURA scheme is then applied to daytime SEVIRI imagery over Europe, for the month of June 2006, at 15-min time increments. The resulting SCOT fields are compared with values obtained by the CloudSat experimental satellite mission, yielding a negligible bias, correlation coefficients ranging from 0.51 to 0.78, and a root mean square difference of 1 to 2 SCOT increments. These findings compare favourably to results from similar intercomparison exercises reported in the literature. Based on the retrieved SCOT from SEVIRI and radiative transfer modelling approach, simple parameterisations are proposed to estimate the surface UV-A and UV-B irradiance. The validation of the modelled UV-A and UV-B irradiance against the measurements over two Belgian stations, Redu and Ostend, indicate good agreement with the high correlation, index of agreement and low bias. The SCOT fields estimated by implementing SACURA on imagery from geostationary satellite are reliable and its impact on surface UV irradiance levels is well produced.

  2. Photocatalytic antibacterial effects are maintained on resin-based TiO2 nanocomposites after cessation of UV irradiation.

    Yanling Cai

    Full Text Available Photocatalysis induced by TiO2 and UV light constitutes a decontamination and antibacterial strategy utilized in many applications including self-cleaning environmental surfaces, water and air treatment. The present work reveals that antibacterial effects induced by photocatalysis can be maintained even after the cessation of UV irradiation. We show that resin-based composites containing 20% TiO2 nanoparticles continue to provide a pronounced antibacterial effect against the pathogens Escherichia coli, Staphylococcus epidermidis, Streptococcus pyogenes, Streptococcus mutans and Enterococcus faecalis for up to two hours post UV. For biomaterials or implant coatings, where direct UV illumination is not feasible, a prolonged antibacterial effect after the cessation of the illumination would offer new unexplored treatment possibilities.

  3. EXPRESSION LEVELS OF SOME ADHESION MOLECULES IN THE INTACT AND UV-IRRADIATED Т-LYMPHOCYTES FROM HUMAN BLOOD

    V. G. Artyukhov

    2009-01-01

    Full Text Available Abstract. While employing an enzyme linked immunosorbent assay, it was shown that UV-sensitivity is different for various adhesion molecules (CD2, CD11a and CD29 at the membranes of T-lymphocytes. Relative photoresistance of CD2 and CD11a antigens to UV irradiation was established at the doses range of 151 to 906 J/m2, a large dose of UV-iradiation (1359 J/m2 exerted a suppressive effect upon their expression level. An immunomodulatory action of UV-radiation was revealed upon expression of CD29 transmembrane protein by T-cells. A dependence between amino acid structure and photosensitivity of CD2, CD11a and CD29 antigens of T lymphocytes is analyzed and discussed.

  4. Laser blood irradiation effect on electrophysiological characteristics of acute coronary syndrome patients

    Khotiaintsev, Sergei N.; Doger-Guerrero, E.; Glebova, L.; Svirid, V.; Sirenko, Yuri

    1996-11-01

    This paper treats electro-physiological effects of the low- level laser irradiation of blood (LBI). The data presented here are based on the observation of almost 200 patients suffering from the acute disruption of coronary blood circulation, unstable angina pectoris and myocardial infarction. Statistically significant changes of the electro-physiological characteristics were observed in the group of 65 patients, treated by the LBI. In particular, the significant 6 percent extension of the effective refractory period was observed. The electrical situation threshold has increased by 20.6 percent. The significant changes of some other important electro-physiological characteristics were within the range of 5-15 percent. In this paper, the data obtained on the LBI effectiveness are compared also with the results obtained on 94 patients who in addition to the standard anti-angina therapy were treated by the autohaemo- transfusion performed simultaneously with the UV-light irradiation of the transfused blood. The results obtained demonstrate the significant positive effect of the low energy LBI. The electrophysiological data obtained have good correlation with observed anti-arrhythmic effect of the LBI. This is proved by the data obtained on the electro- physiological characteristics of the cardiovascular system and by other clinical data on the experimental and control group of patients. In the course of this research the exact effect of the low level LBI was established. LBI led to the pronounced positive changes in electro-physiological characteristics of the cardiovascular system of the patients, it also led to the pronounced anti-arrhythmic effect.

  5. UV or X-irradiation increases the cytoplasmic accumulation of rhodamine 123 in various cancer cell lines

    Purpose: Previous studies indicated that ATP-binding cassette (ABC) membrane transporters protect against UV-induced apoptosis. We investigated the effect of UVB and X-ray irradiation on the export function of these ABC transporters in primary lymphocytes and various cancer cell lines. Material and Methods: We used rhodamine accumulation assays in various human malignant cell lines and peripheral blood lymphocytes (PBL). Cells were irradiated with up to 960 mJ/cm2 and up to 50 Gy of UVB and X-ray, respectively. Results: We demonstrated that UVB as well as X-ray irradiation inhibit the export function of the ABC transporters in a dose-dependent fashion. For PBL, this effect did not correlate with an apoptotic phenotype. In the case of the tumor cell lines, even though the irradiation-induced inhibition of membrane transporters was accompanied by phosphatidylserine exposure, only a minority of cells had lost their mitochondrial membrane potential during the observation period. Furthermore, we demonstrated that the inhibition of membrane transporters is not a general feature of apoptosis. Conclusion: Irradiation inhibits the export function of ABC transporters. Although some of the irradiated cells undergo apoptosis following irradiation, the inhibition is an unique feature accompanying irradiation and not a general hallmark of apoptotic cell death. The inhibition of drug export by irradiation may offer new potential for reverting multidrug resistance of cancer cells. (orig.)

  6. Determinants of skin sensitivity to solar irradiation

    Broekmans, W.; Vink, A.A.; Boelsma, E.; Klöpping-Ketelaars, W.A.A.; Tijburg, L.B.M.; Veer, van 't P.; Poppel, van G.; Kardinaal, A.F.M.

    2003-01-01

    Background: Acute effects of UV irradiation include UV-induced erythema. Sunlight plays an important role in the development of skin cancer. Several predictive factors of UV-induced erythema could also be predictive for skin cancer. Objective: Our objective was to quantitatively assess phenotypical

  7. High-quality polar UV measurements : scientific analyses and transfer of the irradiance scale

    Lakkala, Kaisa

    2010-01-01

    The Earth's ecosystems are protected from the dangerous part of the solar ultraviolet (UV) radiation by stratospheric ozone, which absorbs most of the harmful UV wavelengths. Severe depletion of stratospheric ozone has been observed in the Antarctic region, and to a lesser extent in the Arctic and midlatitudes. Concern about the effects of increasing UV radiation on human beings and the natural environment has led to ground based monitoring of UV radiation. In order to achieve high-quality UV...

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

    Gurlit, W.; Bösch, H.; Bovensmann, H.; Burrows, J.P.; A. Butz; Camy-Peyret, C.; Dorf, M.; Gerilowski, K.; Lindner, A.; S. Noël; U. Platt; F. Weidner; Pfeilsticker, K.

    2004-01-01

    Within the framework of the ENVISAT/-SCIAMACHY satellite validation, solar irradiance spectra are absolutely measured at moderate resolution in the UV/visible spectral range (in the UV from 316.7–418 nm and the visible from 400–652 nm at a full width half maximum resolution of 0.55 nm and 1.48 nm, respectively) from aboard the azimuth-controlled LPMA/DOAS balloon gondola at around 32 km balloon float altitude. After accounting for the atmospheric extinction due to Rayleigh...

  9. Repair of nonreplicating UV-irradiated DNA: cooperative dark repair by Escherichia coli uvr and phr functions

    The system previously used to study recombination of nonreplicating UV-irradiated phage lambda DNA was adapted to study UV repair. Irradiated phages infected undamaged homoimmune lysogens. Pyrimidine dimer content (by treatment with Micrococcus luteus UV endonuclease and alkaline sucrose sedimentation) and a biological activity endpoint (infectivity in transfection of uvrB recA recB spheroplasts) were followed. Unless room light was excluded during DNA extraction procedures, photoreactivation (Phr function) was significant. In uvr Δphr bacteria, repair, by both assays, was very low but not zero. Even when light was totally excluded, Phr function appeared to play a role in Uvr-mediated excision repair: both dimer removal and restoration of infectivity were two to five times as efficient in uvr+ phr+ bacteria as in uvr+ Δphr bacteria. Similarly, UV-irradiated phages plated with higher efficiencies on phr+ than Δphr bacteria even under totally dark conditions. In uvr phr+ repressed infections, removal of dimers from nonreplicating DNA did not increase infectivity as much as in uvr2= infections, suggesting a requirement for repair of nondimer photoproducts by the uvrABC system

  10. Whole tumor antigen vaccination using dendritic cells: Comparison of RNA electroporation and pulsing with UV-irradiated tumor cells

    Benencia Fabian

    2008-04-01

    Full Text Available Abstract Because of the lack of full characterization of tumor associated antigens for solid tumors, whole antigen use is a convenient approach to tumor vaccination. Tumor RNA and apoptotic tumor cells have been used as a source of whole tumor antigen to prepare dendritic cell (DC based tumor vaccines, but their efficacy has not been directly compared. Here we compare directly RNA electroporation and pulsing of DCs with whole tumor cells killed by ultraviolet (UV B radiation using a convenient tumor model expressing human papilloma virus (HPV E6 and E7 oncogenes. Although both approaches led to DCs presenting tumor antigen, electroporation with tumor cell total RNA induced a significantly higher frequency of tumor-reactive IFN-gamma secreting T cells, and E7-specific CD8+ lymphocytes compared to pulsing with UV-irradiated tumor cells. DCs electroporated with tumor cell RNA induced a larger tumor infiltration by T cells and produced a significantly stronger delay in tumor growth compared to DCs pulsed with UV-irradiated tumor cells. We conclude that electroporation with whole tumor cell RNA and pulsing with UV-irradiated tumor cells are both effective in eliciting antitumor immune response, but RNA electroporation results in more potent tumor vaccination under the examined experimental conditions.

  11. Coupled noble gas-hydrocarbon evolution of the early Earth atmosphere upon solar UV irradiation

    Hébrard, E.; Marty, B.

    2014-01-01

    Using a new photochemical model of the Earth's early atmosphere, the relationship between noble gas photoionization and organic photochemistry has been investigated from the Archean eon to the present day. We have found that the enhanced UV emission of the young Sun triggered a peculiar atmospheric chemistry in a CH4-rich early atmosphere that resulted in the increased formation of an organic haze, similar to the preliminary results of a previous study (Ribas et al., 2010). We have investigated the interaction between this haze and noble gases photoionized by the UV light from the younger Sun. Laboratory experiments have shown indeed that ionized xenon trapping into organics (1) is more efficient that other ionized noble gases trapping and (2) results in a significant enrichment of heavy xenon isotopes relative to the light ones (e.g., Frick et al., 1979; Marrocchi et al., 2011). We find moreover preferential photoionization of xenon that peaks at an altitude range comparable to that of the organic haze formation, in contrast to other noble gases. Trapping and fractioning of ionized xenon in the organic haze could therefore have been far more efficient than for other noble gases, and could have been particularly effective throughout the Archean eon, since the UV irradiation flux from the young Sun was expected to be substantially higher than today (Ribas et al., 2010; Claire et al., 2012). Thus we suspect that the unique isotopic fractionation of atmospheric xenon and its elemental depletion in the atmosphere relative to other noble gases, compared to potential cosmochemical components, could have resulted from a preferential incorporation of the heaviest xenon isotopes into organics. A fraction of atmospheric xenon could have been continuously trapped in the forming haze and enriched in its heavy isotopes, while another fraction would have escaped from the atmosphere to space, with, or without isotope selection of the lightest isotopes. The combination of these

  12. Solar UV Irradiances and Associated Issues for the Atmosphere and Ionosphere

    Tobiska, W.

    Several new solar proxies have been developed in the past year as the beginning of a second generation solar UV modeling and forecasting capability. These proxies help characterize the energy input into operational space physics models that provide information content on the neutral thermosphere and ionosphere. Between 1999-2000, a full solar spectrum was developed (SOLAR2000) for use in numerical atmospheric and ionospheric models relevant to climatological studies and the E10.7 index was produced for empirical thermospheric and ionospheric model applications. In 20012002, new proxies have been derived including a sunspot number, Rsn, for use by operational HF radio ray-trace algorithms and the Qeuv thermospheric heating rate for use by the aeronomy community to compare airglow-derived versus solar-derived upper atmosphere heating. The Peuv heat production term has also been developed as an index for comparing solar heating to joule heating on a global scale. The S(t) index is the integrated solar spectrum used for solar radiation pressure calculations related to spacecraft attitude control. Finally, the Tinf is the exospheric temperature that is provided for long-term climate change studies. Second generation modeling and forecasting is in development and includes higher cadence solar input information beyond daily flux values where solar flare characterization will soon become reality. The second generation forecasting is also incorporating improved algorithms ranging from wavelet transforms to solar dynamo theory in order to specify solar variability on seven time scales from nowcast and 72-hour forecast to 5 solar cycle estimation. These new proxies are derivatives of the SOLAR2000 model whose solar irradiance specification is compliant with the developing ISO draft standard WD 21348 for Determining Solar Irradiances.

  13. The acute toxicity of ethanol extract from irradiated Temulawak (curcuma xanthorrizha roxb.) which have anticancer activity

    Pasteurization of herbs and herbal medicinal products have been carried out by several herbal industries, but information about the safety of irradiated herbal medicine is still a little, even the influence of gamma irradiation for pasteurization purpose on the toxicity of crude Temulawak has never been investigated. The ethanol extract of Curcuma xanthorrizha Roxb. has cytotoxic activity which potential as an anticancer. In this research, the acute toxicity tests were carried out to the ethanol extract from Curcuma xanthorrizha without irradiation and irradiated with doses of 5 and 10 kGy. The acute toxicity tests of ethanol extract were conducted in mice by observing the effect of extracts on animal behavior (pharmacologic profile) after a single dose of test material, the development of animal body weight and death every day for 14 days and observed several organ weights on day 14. Acute toxicity test results after administration of extracts on male and female mice a dose up to 7500 mg/kg body weight (BW) showed that no deaths and no significant toxic effect, so that the ethanol extract of Curcuma xanthorrizha without irradiation and irradiated with doses of 5 and 10 kGy can be declared safe. Thus LD50 from ethanol extract of Curcuma xanthorrizha without irradiation and irradiated (5 and 10 kGY) in mice was greater than 7500 mg/kg body weight. (author)

  14. Effect of UV irradiation on free radicals in synthetic melanin and melanin biopolymer from Sepia officinalis – EPR examination

    Zdybel Magdalena; Pilawa Barbara

    2015-01-01

    Free radicals in synthetic melanin and melanin from Sepia officinalis were studied by electron paramagnetic resonance (EPR) spectroscopy. The effect of time of ultraviolet (UV) irradiation on free radicals in these melanins was tested. The samples were exposed to UV during 15, 30, and 60 minutes. EPR spectra were measured with microwaves from an X-band (9.3 GHz) in the range of microwave power of 2.2–70 mW. The performed EPR examinations indicate that high concentrations (~1021–1022 spin/g) o...

  15. The combined action of UV irradiation and chemical treatment on the titanium surface of dental implants

    Spriano, Silvia [Politecnico di Torino, Department of Applied Science and Technology, Corso Duca degli Abruzzi, 24-10129 Torino (Italy); Ferraris, Sara, E-mail: sara.ferraris@polito.it [Politecnico di Torino, Department of Applied Science and Technology, Corso Duca degli Abruzzi, 24-10129 Torino (Italy); Bollati, Daniele; Morra, Marco; Cassinelli, Clara [Nobil Bio Ricerche, Portacomaro (Italy); Lorenzon, Giorgio [Centro Chirurgico, Via Mallonetto, 47, 10032, Brandizzo Torino (Italy)

    2015-09-15

    Highlights: • A combined UV irradiation and H{sub 2}O{sub 2} treatment was applied to titanium surfaces. • A thin, homogeneous, not porous, crack-free and bioactive oxide layer was obtained. • The process significantly improves the biological response of titanium surfaces. • A clinical case demonstrates the effectiveness of the proposed treatment. - Abstract: The purpose of this paper is to describe an innovative treatment for titanium dental implants, aimed at faster and more effective osteointegration. The treatment has been performed with the use of hydrogen peroxide, whose action was enhanced by concomitant exposure to a source of ultraviolet light. The developed surface oxide layer was characterized from the physical and chemical points of view. Moreover osteoblast-like SaOS2 cells were cultured on treated and control titanium surfaces and cell behavior investigated by scanning electron microscope observation and gene expression measurements. The described process produces, in only 6 min, a thin, homogeneous, not porous, free of cracks and bioactive (in vitro apatite precipitation) oxide layer. High cell density, peculiar morphology and overexpression of several genes involved with osteogenesis have been observed on modified surfaces. The proposed process significantly improves the biological response of titanium surfaces, and is an interesting solution for the improvement of bone integration of dental implants. A clinical application of the described surfaces, with a 5 years follow-up, is reported in the paper, as an example of the effectiveness of the proposed treatment.

  16. Decolorization of Methylene Blue with TiO2 Sol via UV Irradiation Photocatalytic Degradation

    Jun Yao

    2010-01-01

    Full Text Available TiO2 sol was prepared for the degradation of methylene blue (MB solution under ultraviolet (UV irradiation. The absorption spectra of MB indicated that the maximum wavelength, 663 nm, almost kept the same. The performance of 92.3% for color removal was reached after 160 min. The particle size of TiO2 sol was about 22.5 nm. X-ray diffraction showed that TiO2 consisted of a single anatase phase. The small size and anatase phase probably resulted in high photocatalytic activity of TiO2 sol. The degradation ratio decreased as the initial concentration of MB increased. The photodegradation efficiency decreased in the order of pH 2>pH 9>pH 7. Regarding catalyst load, the degradation increased with the mass of catalyst up to an amount of 1.5 g⋅L−1 then decreased as the mass continued to increase. The addition of H2O2 to TiO2 sol resulted in an increase on the degradation ratio.

  17. 2-Hydroxypyridine photolytic degradation by 254 nm UV irradiation at different conditions.

    Stapleton, David R; Konstantinou, Ioannis K; Karakitsou, Anastasia; Hela, Dimitra G; Papadaki, Maria

    2009-11-01

    The degradation and mineralisation of (400 mL, 3.15 mM) aqueous solutions of 2-hydroxypyridine (2-HPY), a primary intermediate formed during the photolytic degradation of 2-chloropyridine (2-CPY), 2-bromopyridine (2-BPY) and 2-iodopyridine (2-IPY), was studied at 50 degrees C, under 254 nm UV irradiation in a range of conditions. The rate of 2-HPY disappearance was found to heavily depend on agitation, dissolved oxygen, pH and hydroxyl radical scavenger presence. pH has a pronounced effect on the phototreatment of 2-HPY, i.e. 2-HPY removal is faster at lower pH, but except for their influence on the solution pH, Cl(-) or F(-) do not appear to affect 2-HPY rate of removal or mineralisation. 2-HPY removal rate increases with dissolved oxygen, thus indicating a prominent 2-HPY photooxidation pathway. Helium purging of the solution before and during the measurement reduced 2-HPY removal rate, thus supporting the existence of a photooxidation pathway. Pure photolytic 2-HPY removal, i.e. when photooxidation is limited, fits pseudo-first order kinetics, and a kinetic model was developed for 2-HPY formation and removal during 2-CPY, 2-BPY and 2-IPY photolytic degradation under laminar flow. The addition of radical scavenger (tert-butanol) had a detrimental effect on the photolytic degradation of 2-HPY. Complete total organic carbon removal was achieved. PMID:19772980

  18. The combined action of UV irradiation and chemical treatment on the titanium surface of dental implants

    Highlights: • A combined UV irradiation and H2O2 treatment was applied to titanium surfaces. • A thin, homogeneous, not porous, crack-free and bioactive oxide layer was obtained. • The process significantly improves the biological response of titanium surfaces. • A clinical case demonstrates the effectiveness of the proposed treatment. - Abstract: The purpose of this paper is to describe an innovative treatment for titanium dental implants, aimed at faster and more effective osteointegration. The treatment has been performed with the use of hydrogen peroxide, whose action was enhanced by concomitant exposure to a source of ultraviolet light. The developed surface oxide layer was characterized from the physical and chemical points of view. Moreover osteoblast-like SaOS2 cells were cultured on treated and control titanium surfaces and cell behavior investigated by scanning electron microscope observation and gene expression measurements. The described process produces, in only 6 min, a thin, homogeneous, not porous, free of cracks and bioactive (in vitro apatite precipitation) oxide layer. High cell density, peculiar morphology and overexpression of several genes involved with osteogenesis have been observed on modified surfaces. The proposed process significantly improves the biological response of titanium surfaces, and is an interesting solution for the improvement of bone integration of dental implants. A clinical application of the described surfaces, with a 5 years follow-up, is reported in the paper, as an example of the effectiveness of the proposed treatment

  19. Photocatalytic degradation of phenol by iodine doped tin oxide nanoparticles under UV and sunlight irradiation

    Highlights: • A sol–gel method used to synthesize tin oxide nanoparticles. • Nanoparticles of tin oxide doped with different iodine concentrations. • Degradation studies carried up with UV–vis, TOC, HPLC and GC instruments. • 1% iodine doped tin dioxide showed maximum photodegradation efficiency. - Abstract: Iodine doped tin oxide (SnO2:I) nanoparticles were prepared by sol–gel synthesis and their photocatalytic activities with phenol as a test contaminant were studied. In the presence of the catalysts, phenol degradation under direct sunlight was comparable to what was achieved under laboratory conditions. Photocatalytic oxidation reactions were studied by varying the catalyst loading, light intensity, illumination time, pH of the reactant and phenol concentration. Upon UV irradiation in the presence of SnO2:I nanoparticles, phenol degrades very rapidly within 30 min, forming carboxylic acid which turns the solution acidic. Phenol degradation rate with 1% iodine doped SnO2 nanoparticles is at least an order of magnitude higher compared to the degradation achieved through undoped SnO2 nanoparticles under similar illumination conditions

  20. Photocatalytic degradation of phenol by iodine doped tin oxide nanoparticles under UV and sunlight irradiation

    Al-Hamdi, Abdullah M.; Sillanpää, Mika [Laboratory of Green Chemistry, Lappeenranta University of Technology, Sammonkatu 12, 50130 Mikkeli (Finland); Dutta, Joydeep, E-mail: dutta@squ.edu.om [Chair in Nanotechnology, Water Research Center, Sultan Qaboos University, P.O. Box 17, 123 Al-Khoudh (Oman)

    2015-01-05

    Highlights: • A sol–gel method used to synthesize tin oxide nanoparticles. • Nanoparticles of tin oxide doped with different iodine concentrations. • Degradation studies carried up with UV–vis, TOC, HPLC and GC instruments. • 1% iodine doped tin dioxide showed maximum photodegradation efficiency. - Abstract: Iodine doped tin oxide (SnO{sub 2}:I) nanoparticles were prepared by sol–gel synthesis and their photocatalytic activities with phenol as a test contaminant were studied. In the presence of the catalysts, phenol degradation under direct sunlight was comparable to what was achieved under laboratory conditions. Photocatalytic oxidation reactions were studied by varying the catalyst loading, light intensity, illumination time, pH of the reactant and phenol concentration. Upon UV irradiation in the presence of SnO{sub 2}:I nanoparticles, phenol degrades very rapidly within 30 min, forming carboxylic acid which turns the solution acidic. Phenol degradation rate with 1% iodine doped SnO{sub 2} nanoparticles is at least an order of magnitude higher compared to the degradation achieved through undoped SnO{sub 2} nanoparticles under similar illumination conditions.

  1. Formation of Nucleobases from the UV Irradiation of Pyrimidine in Astrophysical Ice Analogs

    Sandford, Scott A.; Nuevo, Michel; Materese, Christopher K.

    2014-01-01

    Nucleobases are the informational subunits of DNA and RNA. They consist of Nheterocycles that belong to either the pyrimidine-base group (uracil, cytosine, and thymine) or the purinebase group (adenine and guanine). Several nucleobases, mostly purine bases, have been detected in meteorites [1-3], with isotopic signatures consistent with an extraterrestrial origin [4]. Uracil is the only pyrimidine-base compound formally reported in meteorites [2], though the presence of cytosine cannot be ruled out [5,6]. However, the actual process by which the uracil was made and the reasons for the non-detection of thymine in meteorites have yet to be fully explained. Although no N-heterocycles have ever been observed in the ISM [7,8], the positions of the 6.2-µm interstellar emission features suggest a population of such molecules is likely to be present [9]. In this work we study the formation of pyrimidine-based molecules, including the three nucleobases uracil, cytosine, and thymine from the ultraviolet (UV) irradiation of pyrimidine in ices consisting of several combinations of H(sub2)O, NH(sub3), CH(sub3)OH, and CH(sub4) at low temperature, in order to simulate the astrophysical conditions under which prebiotic species may be formed in the interstellar medium, in the protosolar nebula, and on icy bodies of the Solar System.

  2. Modeling the EUV/UV irradiance within the FP7 SOLID Project

    Haberreiter, Margit; Delouille, Veronique; Del Zanna, Giulio; Dammasch, Ingolf; Dominique, Marie; Dudok de Wit, Thierry; Ermolli, Ilaria; Jones, Andrew; Kretzschmar, Matthieu; Mampaey, Benjamin; Schaefer, Robert; Schmidtke, Gerhard; Schoell, Micha; Thuillier, Gerard; Verbeeck, Cis; Wieman, Seth; Woods, Tom; Schmutz, Werner

    2015-04-01

    The solar EUV irradiance has strong effects on the Earth's ionosphere and thermosphere. Here we present latest results for the EUV spectral range carried out within the European FP7 Project SOLID. Specifically, we model the SSI variations in the EUV spectral range based on the analysis of images obtained with SOHO/EIT, PROBA2/SWAP, and SDO/AIA. These images are segmented to regions of solar activity using the SPoCA tool. Moreover, with the SOLar MODeling code (SOLMOD) we calculate intensity spectra representing the intensity emitted by these regions. We present the latest set of reconstructions and compare it to available data, such as SOHO/SEM, PROBA2/LYRA, ISS/SOLAR/SOLACES, and SDO/EVE. Furthermore, we will present a probabilistic method to obtain a consistent composite from the available data. These results are an important for understanding the spectral variability in the EUV/UV and as well as its effect on the Earth's upper atmosphere.

  3. Sugar and Sugar Derivatives in Residues Produced from the UV Irradiation of Astrophysical Ice Analogs

    Nuevo, M.; Sandford, S. A.; Cooper, G.

    2016-01-01

    A large variety and number of organic compounds of prebiotic interest are known to be present in carbonaceous chondrites. Among them, one sugar (dihydroxyacetone) as well as several sugar acids, sugar alcohols, and other sugar derivatives have been reported in the Murchison and Murray meteorites. Their presence, along with amino acids, amphiphiles, and nucleobases strongly suggests that molecules essential to life can form abiotically under astrophysical conditions. This hypothesis is supported by laboratory studies on the formation of complex organic molecules from the ultraviolet (UV) irradiation of simulated astrophysical ice mixtures consisting of H2O, CO, CO2, CH3OH, CH4, NH3, etc., at low temperature. In the past 15 years, these studies have shown that the organic residues recovered at room temperature contain amino acids, amphiphiles, nucleobases, as well as other complex organics. However, no systematic search for the presence of sugars and sugar derivatives in laboratory residues have been reported to date, despite the fact that those compounds are of primary prebiotic significance. Indeed, only small (up to 3 carbon atoms) sugar derivatives including glycerol and glyceric acid have been detected in residues so far.

  4. Ametryn degradation in the ultraviolet (UV) irradiation/hydrogen peroxide (H{sub 2}O{sub 2}) treatment

    Gao Naiyun [State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092 (China); Deng Yang, E-mail: ydeng@uprm.edu [Department of Civil Engineering and Surveying, University of Puerto Rico, Mayagueez Campus, PO BOX 9041, Mayagueez, 00681-9041 (Puerto Rico); Zhao Dandan [State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092 (China)

    2009-05-30

    Ultraviolet (UV) irradiation (253.7 nm) in the presence of hydrogen peroxide (H{sub 2}O{sub 2}) was used to decompose aqueous ametryn. The concentrations of ametryn were measured with time under various experiment conditions. The investigated factors included H{sub 2}O{sub 2} dosages, initial pH, initial ametryn concentrations, and a variety of inorganic anions. Results showed that ametryn degradation in UV/H{sub 2}O{sub 2} process was a pseudo-first-order reaction. Removal rates of ametryn were greatly affected by H{sub 2}O{sub 2} dosage and initial concentrations of ametryn, but appeared to be slightly influenced by initial pH. Furthermore, we investigated the effects of four anions (SO{sub 4}{sup 2-}, Cl{sup -}, HCO{sub 3}{sup -}, and CO{sub 3}{sup 2-}) on ametryn degradation by UV/H{sub 2}O{sub 2}. The impact of SO{sub 4}{sup 2-} seemed to be insignificant; however, Cl{sup -}, HCO{sub 3}{sup -}, and CO{sub 3}{sup 2-} considerably slowed down the degradation rate because they could strongly scavenge hydroxyl radicals (OH{center_dot}) produced during the UV/H{sub 2}O{sub 2} process. Finally, a preliminary cost analysis revealed that UV/H{sub 2}O{sub 2} process was more cost-effective than the UV alone in removal of ametryn from water.

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

    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.

  6. Immunologic effects of whole body ultraviolet (uv) irradiation. II. Defect in splenic adherent cell antigen presentation for stimulation of T cell proliferation

    Ultraviolet (uv) irradiation has been shown to alter many parameters of the immunologic reactivity of mice. The altered responsiveness of uv-irradiated mice, as measured by delayed-type hypersensitivity (DTH) and primary in vitro plaque-forming cell (PFC) responses to T-dependent antigens, has recently been correlated with a functional defect in the splenic adherent cell population of these animals. The present studies describe a model of this altered responsiveness, which allows further clarification of the effects of external uv irradiation on the splenic antigen-presenting cell (APC) in its interactions with T cells

  7. Corticosteroids prevent acute lung dysfunction caused by thoracic irradiation in unanesthetized sheep

    We sought to determine the effect of corticosteroid therapy in a new acute model of oxidant lung injury, thoracic irradiation in awake sheep. Sheep were irradiated with 1,500 rads to the whole chest except for blocking the heart and adjacent ventral lung. Seven experimental sheep were given methylprednisolone (1 g intravenously every 6 h for four doses) and thoracic irradiation; control sheep received only irradiation. In irradiated control sheep, lung lymph flow increased from baseline (7.6 ml/h) to peak at 3 h (13.2), and lung lymph protein clearance increased from 5.1 to 9.7 ml/h. Mean pulmonary artery pressure increased in the irradiated control sheep from 19 to 32.4 cm H2O, whereas the lung lymph thromboxane concentration increased from 0.09 to 6.51 ng/ml at 3 h. Arterial oxygen tension in irradiated control sheep fell gradually from 86 mm Hg at baseline to 65 mm Hg at 8 h. Methylprednisolone administration significantly prevented the increase in lung lymph protein clearance, mean pulmonary artery pressure, and lung lymph thromboxane concentration. Methylprednisolone also prevented the fall in arterial oxygen tension after thoracic irradiation, but did not prevent a further decrease in lymphocytes in blood or lung lymph after radiation. We conclude that corticosteroid therapy prevents most of the acute physiologic changes caused by thoracic irradiation in awake sheep

  8. Adsorptive Properties of Dyes to Cellulosic Sheet and Discoloration of Dye Solution by UV-ray Irradiation

    Zhou Yu; Iida Ikuho; Minato Kazuya; Kurosu Hiroshi

    2005-01-01

    The adsorptive properties and selectivity of dyes and water molecules to cellulosic sheet, dependence of adsorptive properties of dyes on the concentration of dye solution, and discoloration of the dye solution due to the UV-ray irradiation were determined for 18 kinds of commercial dyes. The results are as follows: 1) the adsorptive properties of dyes to cellulose sheet differed greatly, but did not depend on the dye types such as acidic, basic and so on; 2) adsorptive properties of dyes to cellulosic sheet depended on the concentration of dye solution and were classified into 4 types: concentration-independent, increasing or decreasing with dye concentration, and having a maximum. This classification was irrelevant to the dye types; 3) the irradiation of UV-ray did not cause significant discoloration of dye solution itself, which suggested that wood components as well as dye molecules influence the discoloration of wood.

  9. Disinfection of hepatitis A virus and MS-2 coliphage in water by ultraviolet irradiation: comparison of UV-susceptibilty

    Ultraviolet irradiation is gaining importance as a disinfection procedure for drinking water and in waste water treatment. Since water is one of the main transmission routes of hepatitis A virus the susceptibility of Hepatitis A Virus (HAV) to UV rays is of special interest. MS-2 coliphage resembles HAV in size and structure, is easy to handle, and might therefore serve as indicator organism for the assessment of water quality and for evaluating the quality of water treatment processes. Hepatitis A virus and MS-2 coliphage were suspended in 0.9% sodium chloride solution and were irradiated in a 20-ml quartz cuvette at 254 nm. For a reduction rate of four log units a three times higher UV dose was required with MS-2 than with HAV. (author)

  10. Hydrophilicity and hydrophobicity control of polypropylene films by UV-assisted irradiation in the presence of reactive vapors

    Polypropylene (PP) thin film surfaces were modified using the UV-assisted technique in the presence of reactive vapors producing films with hydrophobic or hydrophilic properties. The irradiations were carried out in the presence of Trimethoxypropylsilane (TMPSi) or Acrylic Acid (AA) vapors. When TMPSi was used as reactive vapor atmosphere the final PP surface obtained was hydrophobic with a contact angle (WCA) of ∼ 145 degrees. On the contrary, when AA vapors were used during irradiation the treated surface presented hydrophilic properties (WCA ∼ 40 degree). The surface modifications were analyzed by WCA and FTIR-ATR (UFRGS) and by NEXAFS spectroscopy (Laboratorio Nacional de Luz Sincrotron, LNLS, Campinas). NEXAFS spectroscopy showed evidence that new films with different chemical properties to PP were formed. For example, when AA vapors were used during the UV photolysis, a polyacrylic film was formed on the PP surface. XPS analysis of the modified films is under way. (author)

  11. Photoreactivation of UV-irradiated Legionella pneumophila and other Legionella species

    Shortwave UV light was assessed as a feasible modality for the control of Legionnaires disease bacterium in water. The results of this study show that Legionella pneumophila and six other Legionella species are very sensitive to low doses of UV. However, all Legionella species tested effectively countered the germicidal effect of UV when subsequently exposed to photoreactivating light

  12. Synthesis of Se nanoparticles by using TSA ion and its photocatalytic application for decolorization of cango red under UV irradiation

    In this study, we describe a size-controlled synthesis of selenium nanoparticles based on the reduction of selenious acid (H2SeO3) by UV-irradiated tungstosilicate acid (H4SiW12O40, TSA) solution which serves both as reducing reagent and stabilizer. The nanoparticles are characterized by ultraviolet-visible spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS), the Raman spectra, transmission electron microscopy (TEM) and Zetasizer, respectively. The characteristic catalytic behavior of the Se nanoparticles is established by studying the decolorization of cango red in the presence of UV light. It is obvious that selenium catalyzes the reaction efficiently. The results show that the rate of dye decolorization varies linearly with the nanoparticle concentration and the rate of dye decolorization decreases with the size of the Se nanoparticles increasing

  13. Synthesis of PMA stabilized silver nanoparticles by chemical reduction process under a two-step UV irradiation

    Poly(methacrylic acid) (PMA) stabilized silver nanoparticles (Ag NPs), also used in the surface modification of clothing fibers, were fabricated via chemical reduction processes under UV irradiation. To obtain an uniform size distribution it has been designed a new 'two-step' process which employs two different UV radiation densities in order to control the kinetics of NPs nucleation. The as produced nanoparticles were characterized by UV-vis absorption spectroscopy and TEM microscopy. The results show the reduction of the Ag ions and the nanoparticles nucleation in the first step. In the second step, the final Ag NPs size distribution is controlled through a quick cross-linking of the PMA that freezes out any further modification. A narrow size distribution with more than 80% NPs smaller than 10 nm and none larger than 25 nm was obtained and the long-term stability (one month) of the colloidal solution was verified.

  14. Lethality and the depression on DNA synthesis in UV-irradiated normal human and xeroderma pigmentosum cells

    Ultraviolet radiation suppresses the semiconservative DNA replication in mammalian cells. The rate of DNA synthesis is initially depressed and later recovers after low doses of UV radiation in human cells. Such a response is more sensitive to UV radiation in cells derived from patients with xeroderma pigmentosum (XP) than that in normal human cells. The relative rate of DNA synthesis is not always correlated with cell survival because, unlike cell survival, the dose-response curve of the relative rate of DNA synthesis shows the biphasic nature of the sensitivity. In the experiments reported herein, the total amount (not the rate) of DNA synthesized during a long interval of incubation which covers the period of inhibition and recovery (but not longer than one generation time) after irradiation with various doses of UV radiation was examined in normal human and XP cells, and was found to be well correlated with cell survival in all the cells tested. (Auth.)

  15. Preparation, characterization and application of nanosized copper ferrite photocatalysts for dye degradation under UV irradiation

    Zaharieva, Katerina, E-mail: zaharieva@ic.bas.bg [Institute of Catalysis, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Block 11, 1113 Sofia (Bulgaria); Rives, Vicente, E-mail: vrives@usal.es [GIR-QUESCAT, Dpto. Química Inorgánica, Universidad de Salamanca, 37008 Salamanca (Spain); Tsvetkov, Martin, E-mail: mptsvetkov@gmail.com [Faculty of Chemistry and Pharmacy, St. Kliment Ohridski University of Sofia, 1 J. Bourchier Blvd., 1164 Sofia (Bulgaria); Cherkezova-Zheleva, Zara, E-mail: zzhel@ic.bas.bg [Institute of Catalysis, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Block 11, 1113 Sofia (Bulgaria); Kunev, Boris, E-mail: bkunev@ic.bas.bg [Institute of Catalysis, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Block 11, 1113 Sofia (Bulgaria); Trujillano, Raquel, E-mail: rakel@usal.es [GIR-QUESCAT, Dpto. Química Inorgánica, Universidad de Salamanca, 37008 Salamanca (Spain); Mitov, Ivan, E-mail: mitov@ic.bas.bg [Institute of Catalysis, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Block 11, 1113 Sofia (Bulgaria); Milanova, Maria, E-mail: nhmm@wmail.chem.uni-sofia.bg [Faculty of Chemistry and Pharmacy, St. Kliment Ohridski University of Sofia, 1 J. Bourchier Blvd., 1164 Sofia (Bulgaria)

    2015-06-15

    {sup −3} min{sup −1}) for degradation of organic dye Malachite green under UV irradiation. - Highlights: • Copper ferrites via co-precipitation, mechanochemical and/or thermal treatment. • Nano ferrites show a superparamagnetic and collective magnetic excitations nature. • The co-precipitated Cu{sub 0.25}Fe{sub 2.75}O{sub 4} posses the highest photocatalytic activity. • The amount adsorbed Malachite Green by catalyst depends on the preparation method. • The prepared copper ferrites can be applicable as cheap adsorbents and catalysts.

  16. Effect of lactic acid and UV irradiation on the cassava and corn starches

    Célia Maria Landi Franco

    2010-04-01

    Full Text Available In this work, the effect of lactic acid and UV irradiation on the physicochemical and structural characteristics of cassava and corn starches was evaluated. Only the modified cassava starch presented baking expansion capacity. From RVA, reduction of viscosity values, greater internal stability and none set back for modified cassava starch were observed. Modified corn starch did not show any peak viscosity. There were no significant differences in DSC thermal properties of treated and native starches. Amylopectin and amylose molecules from both the modified starches displayed some degradation. Molecular weight of cassava amylopectin was mostly preserved, whereas corn amylopectin was evenly attacked through the granule. Nevertheless, the B long branched chains of cassava amylopectin, with DP~37, were degraded whereas they were unchanged for corn amylopectin.Amido de mandioca modificado com ácido lático e radiação ultravioleta antes da secagem artificial têm mostrado boa capacidade de expansão, a exemplo da encontrada para o polvilho azedo. Neste trabalho, os efeitos do ácido lático e radiação UV sobre as características físico-químicas e estruturais de amidos de mandioca e milho foram investigados. Apenas o amido de mandioca modificado apresentou capacidade de expansão durante o forneamento. Do RVA, redução dos valores de viscosidade, boa estabilidade interna e nenhuma tendência a retrogradação para este amido modificado foi observado. O amido de milho não apresentou qualquer pico de viscosidade após modificação. Não foram observadas diferenças significativas nas propriedades térmicas, determinadas em DSC, entre os amidos nativos e modificados de ambas as fontes. As moléculas de amilopectina e amilose de ambos os amidos modificados mostraram alguma degradação. O peso molecular da amilopectina do amido de mandioca foi mais preservado, enquanto a amilopectina do amido de milho foi mais atacada em todo o grânulo. As

  17. Skin anti-photoaging properties of ginsenoside Rh2 epimers in UV-B-irradiated human keratinocyte cells

    Sun-Joo Oh; Sihyeong Lee; Woo-Yong Choi; Chang-Jin Lim

    2014-09-01

    Ginseng, one of the most widely used herbal medicines, has a wide range of therapeutic and pharmacological applications. Ginsenosides are the major bioactive ingredients of ginseng, which are responsible for various pharmacological activities of ginseng. Ginsenoside Rh2, known as an antitumour ginsenoside, exists as two different stereoisomeric forms, 20()-ginsenoside Rh2 [20()-Rh2] and 20()-ginsenoside Rh2 [20()-Rh2]. This work aimed to assess and compare skin anti-photoaging activities of 20()-Rh2 and 20()-Rh2 in UV-B-irradiated HaCat cells. 20()-Rh2, but not 20()-Rh2, was able to suppress UV-B-induced ROS production in HaCat cells. Both stereoisomeric forms could not modulate cellular survival and NO level in UV-B-irradiated HaCat cells. Both 20()-Rh2 and 20()-Rh2 exhibited suppressive effects on UV-B-induced MMP-2 activity and expression in HaCat cells. In brief, the two stereoisomers of ginsenoside Rh2, 20()-Rh2 and 20()-Rh2, possess skin anti-photoaging effects but possibly in different fashions.

  18. Antigen-specific immune-suppressor factor in herpes simplex virus type 2 infections of UV B-irradiated mice

    UV B-irradiation (280 to 320 nm) of mice at the site of cutaneous infection with herpes simplex virus type 2 (HSV-2) induced suppressor T-cell circuits that decreased HSV-2-induced proliferative responses of HSV-2-immune lymph node cells. Adoptive transfer experiments indicated that splenocytes from UV B-irradiated HSV-2-infected animals contain L3T4+ cells that suppress proliferative responses in vivo, consistent with suppressor inducer cells. However, following in vitro culture of the splenocytes with HSV-2 antigen, the proliferation of immune lymph node cells was inhibited by Lyt2+ suppressor T cells, consistent with antigen-induced suppressor effector cells. Antigen-specific and nonspecific suppressor factors were fractionated from supernatants of HSV-2-stimulated spleen cells by molecular-sieve chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the Sephadex fraction that contained the antigen-specific suppressor factor, in the presence or absence of 2-mercaptoethanol, defined a 115-kilodalton protein consisting of two disulfide-bound components with molecular sizes of 70 and 52 kilodaltons. The implications of these results with respect to the regulation of HSV-induced cell-mediated immunity following UV B-irradiation are discussed

  19. Degradation of polycyclic aromatic hydrocarbons in crumb tyre rubber catalysed by rutile TiO2 under UV irradiation.

    Yu, Kai; Huang, Linyue; Lou, Lan-Lan; Chang, Yue; Dong, Yanling; Wang, Huan; Liu, Shuangxi

    2015-01-01

    The polycyclic aromatic hydrocarbons (PAHs) in crumb tyre rubber were firstly degraded under UV irradiation in the presence of rutile TiO2 and hydrogen peroxide. The effects of light intensity, catalyst amount, oxidant amount, initial pH value, co-solvent content, and reaction time on degradation efficiency of typical PAHs in crumb tyre rubber were studied. The results indicated that UV irradiation, rutile TiO2, and hydrogen peroxide were beneficial to the degradation of PAHs and co-solvent could accelerate the desorption of PAHs from crumb tyre rubber. Up to 90% degradation efficiency of total 16 PAHs could be obtained in the presence of rutile TiO2 (1 wt%) and hydrogen peroxide (1.0 mL) under 1800 µW cm(-2) UV irradiation for 48 h. The high molecular weight PAHs (such as benz(a)pyrene) were more difficult to be degraded than low molecular weight PAHs (such as phenanthrene, chrysene). Moreover, through the characterization of reaction solution and degradation products via GC-MS, it was proved that the PAHs in crumb tyre rubber were successfully degraded. PMID:25323028

  20. Photoreactivation of pyrimidine dimers generated by a photosensitized reaction in RNA of the Smittia sp. embryos after UV-irradiation

    Mechanisms of biological effects resulting from the irradiation of Smittia sp. embryos in an early stage of developmentment with UV rays with the wave-length of 265, 285 and 295 nm are investigated. It is shown that the cessation of development, deceleration of protein synthesis and emergence of additional abdomens after the irradiation of embryos in early stages of development are not connected with the damage of the nucleus but with the formation of pyrimidine dimers in RNA in the cortical layer of ovum cytoplasm. At first, the energy of UV rays with the given wave-lengths is accepted in the cell by molecules-photosensitizers. It is shown for the first time that pyrimidine dimers generated in RNA can be photoreactivated on exposure of cells to light. Maternal RNA accumulated during oogenesis play an important role in the early embryogeny of insects and other animals ova developing in the sunlight. Therefore, the protection of embryo RNA from solar UV irradiation damage is provided for by the mechanisms of RNA pyrimidine dimers photoreactivation resulted from the sunlight long waves

  1. MITOSIS ANA-THELOPHASE CHROMOSOMAL ABERRATIONS INDUCED BY UV IRRADIATION UNDER THE ANTIOXIDATIVE PROTECTION OF VITAMIN C, BY CALENDULA OFFICINALIS L.

    Csilla Iuliana Bara

    2014-07-01

    Full Text Available due to the stratospheric ozone layer depletion, the researches focused in the last decades on the study of solarradiations reaching Earth surface. The target of the study was to establish the biological response of Calendula officinalisL. to UV irradiation, under the anti-oxidative protection of vitamin C, (which helps next to UV induced anti-oxidativeenzymes, in the protection against a large variety of products capable to induce free radicals formation.Our investigations were focused on detecting chromosomal aberrations which occurs during cells in division in meristemroot tips, under UV irradiation for 15 or 30 minutes, in the presence or absence of vitamin C, reported to the non-irradiated control samples. Regarding the mitotic index, it could be noticed an inhibition of cell division frequency underUV stress for all irradiated variants, not depending of presence or absence of vitamin C, positively correlated with theincrease of irradiation period. Maximal chromosomal aberrations frequency, were induced by UV radiations in the roottips of seedlings germinated in the absence of vitamin C, decreasing in the presence of vitamin C, due to the antioxidantprotective role of this. In the absence of UV irradiation, the chromosomal aberrations frequency was lower comparingwith irradiated variants, for all seedlings, even if germinated in the presence or absence of vitamin C. Betweenchromosomal aberrations were detected: bridges, expulsed and retardate chromosomes, fragments.

  2. Effect of UV irradiation on low concentration methanol solutions in BWR condition loop testing

    The reactor pressure vessel (RPV) internals play a significant role in BWRs with respect to ensuring the function of several neutron flux controlling components in the reactor core. Effective countermeasures to prevent the RPV internals from stress corrosion cracking (SCC) are needed, especially, if locally sensitized or cold-worked materials are exposed to oxygenated high-temperature water (HTW). Consequently, mitigation techniques are necessary to reduce the dissolved oxidant concentration as oxygen and hydrogen peroxide to shift the corrosion and redox potentials of materials to more negative values (as e.g. ECP < -230 mVSHE for austenitic stainless steel). The beneficial effect of the alternative reductant MeOH was confirmed by test runs in a pipe reactor especially designed for these tests at T = 150 deg. C. One of the most important results is that MeOH injection in oxygenated high-temperature water (HTW) with simultaneous irradiation of the test solution by Vacuum UV (VUV) light (photolysis) is sufficient to significantly shift the corrosion potentials to more negative values already at a molar ratio (MeOH/DO) of ≥ 1. The photon energies of VUV light (6.2 to 12.4 eV) are high enough to crack the bonds in the water molecule and to generate radicals, ions and free electrons. VUV-light, thus, generates effects similar to Cherenkov radiation with a wavelength of 100 to 400 nm in the vessel of LWRs. The early injection techniques during plant start-up may become one of the advantages of MeOH injection at BWR plants. Hence, the MeOH-effect at molar ratios between 1 and 2 has to be studied more carefully to be sure that in this temperature regime the dosage of MeOH is reasonable. (authors)

  3. Photocatalytic Activity and Optical Properties of Blue Persistent Phosphors under UV and Solar Irradiation

    C. R. García

    2016-01-01

    Full Text Available Blue phosphorescent strontium aluminosilicate powders were prepared by combustion synthesis route and a postannealing treatments at different temperatures. X-ray diffraction analysis showed that phosphors are composed of two main hexagonal phases: SrAl2O4 and Sr3Al32O51. The morphology of the phosphors changed from micrograins (1000°C to a mixture of bars and hexagons (1200°C and finally to only hexagons (1300°C as the annealing temperature is increased. Photoluminescence spectra showed a strong blue-green phosphorescent emission centered at λem=455 nm, which is associated with 4f65d1→4f6  (8S7/2 transition of the Eu2+. The sample annealed at 1200°C presents the highest luminance value (40 Cd/m2 with CIE coordinates (0.1589, 0.1972. Also, the photocatalytic degradation of methylene blue (MB under UV light (at 365 nm was monitored. Samples annealed at 1000°C and 1300°C presented the highest percentage of degradation (32% and 38.5%, resp. after 360 min. In the case of photocatalytic activity under solar irradiation, the samples annealed at 1000°C, 1150°C, and 1200°C produced total degradation of MB after only 300 min. Hence, the results obtained with solar photocatalysis suggest that our powders could be useful for water cleaning in water treatment plants.

  4. Residual Gas Analysis of Samples Formed from the UV Irradiation of Astrophysical Ice Analogs

    Materese, C. K.; Nuevo, M.; Sandford, S. A.

    2011-05-01

    The formation of complex organics, including nucleic acids, amino acids, sugars, and other molecules of prebiotic interest, in an interstellar environment is an important field of modern astrochemistry research. In a typical experiment, we perform a controlled deposition of a known mixture of gas onto a cold finger while irradiating the sample to simulate the conditions of cold interstellar grains (Bernstein et al., 1995, 2002; Muñoz Caro et al., 2002; Nuevo et al., 2008, 2009, 2010). After the deposition is complete, the sample is warmed and recovered for analysis. Our traditional analysis methods have made extensive use of HPLC with UV-visible detection, GC-MS, and IR spectroscopy when appropriate. While these techniques provide significant insight into the photo-processing of our ices, they invariably lead to the loss of some volatiles during the warm-up, which may be of interest. In order to learn more about the volatiles lost during the warm-up we have installed a residual gas analyzer (RGA) mass spec device on one of our vacuum systems. With this tool, we can perform controlled warm-ups of our samples and monitor the composition of outgassing volatiles as a function of temperature change. Knowledge of the composition of these volatiles could prove invaluable in two ways. First, we may observe important chemical species, which we are unable to detect with our other methods because they are either lost during the warm-up, or cannot be detected using our GC-MS protocol. Second, even compounds which are mundane in and of themselves, may provide important clues about the type of chemistry occurring within the rest of the ice. We are currently using the RGA to study the formation of pyrimidine-based nucleobases from in interstellar ice analogs. In the future we will expand our studies to purines-based nucleic acids, amino acids, and other prebiotic organics.

  5. Radiation-induced and postirradiation changes in forest biogeocenosis after acute gamma-irradiation

    A study was made of the entomological destruction of pine tress in a pine/birch forest subjected to acute irradiation with doses ranging within the stand from 1 to 230 Gy. A sharp increase in number of xylogenous insects was noted in the exposed forest on the 4th year after irradiation. The degree of setting of xylophagous insects on tress was shown to depend upon the developmental class of a t tree and the absorbed dose

  6. Effects of UV irradiation on humic acid removal by ozonation, Fenton and Fe0/air treatment: THMFP and biotoxicity evaluation

    Highlights: → Fe0/air rapidly and effectively removed HA within 9 min and its COD, biotoxicity and THMFP were low. → THMFP of ozonation-treated solution was much higher than those of Fenton-treated and Fe0/air-treated solutions. → UV irradiation during ozonation and Fenton oxidation enhanced HA removal, but did not reduce the THMFP of the treated solutions. → Fe0/air treatment with UV irradiation obviously increased the THMFP of the treated solution. → The relationship between biotoxicity and chloroform in the chlorinated solution was insignificant. - Abstract: Effects of UV irradiation on humic acid (HA) removal by Fe0/air, ozonation and Fenton oxidation were investigated. The trihalomethane forming potential (THMFP) and toxicity of treated solutions were also evaluated. The experimental conditions were ozone of 21 mg min-1, H2O2 of 8 x 10-4 M, Fe0 of 20 g L-1, air flow of 5 L min-1, and UVC of 9 W. Results indicated that Fe0/air rapidly removed HA color (>99%) and COD (90%) within 9 min. 51-81% of color and 43-50% of COD were removed by ozonation and Fenton oxidation after 60 min. Both UV enhanced ozone and Fenton oxidation removed HA, but the Fe0/air process did not. Spectrum results showed all processes effectively diminished UV-vis spectra, except for ozonation. The THMFP of Fe0/air-treated solution (114 μg L-1) was much lower than those of Fenton- (226 μg L-1) and ozonation-treated solutions (499 μg L-1). Fe0/air with UV irradiation obviously increased the THMFP of treated solution (502 μg L-1). The toxicity results obtained from Vibrio fischeri light inhibition test indicated that the toxicity of Fe0/air-treated solution (5%) was much lower than that of ozonation- (33%) and Fenton-treated solutions (31%). Chlorination increased the solution toxicity. The correlation between biotoxicity and chloroform in the chlorinated solution was insignificant.

  7. Cyclobutane-type pyrimidine photodimer formation and induction of ornithine decarboxylase in human skin fibroblasts after UV irradiation

    Cyclobutane-type pyrimidine photodimers as well as the induction of ornithine decarboxylase (ODC) may serve as biochemical markers of the mutagenic and carcinogenic effects of ultraviolet light (UV). For this reason, it is important to compare the formation of pyrimidine dimers with the induction of ODC in human skin fibroblasts after irradiation with UVC (200-290 nm) and UVB (290-320 nm). In our studies we determined cytosine-thymine (C-T) as well as thymine-thymine dimer yields (T-T) by high-pressure liquid chromatography in cultures of neonatal normal human foreskin-derived fibroblasts after irradiation with UVC and UVB light. It was found that the yield of dimerization and the ratio of T-T/C-T decreased from the UVC to the UVB region. Time-course studies of ODC-induction in the same cells indicated that the maximal activity after UVB irradiation was retarded compared to UVC exposure. For the UV-induced ODC-levels, however, no significant difference in maximal induction could be measured after UVC and UVB irradiation at fluences where comparable yields of thymine dimerization are produced. Similar ODC-maxima were obtained with strains from children, while cells from adults showed significantly less pronounced ODC induction, indicating that ODC-response decreases with age and may therefore be used as a marker of aging

  8. UV-Vis, infrared, and mass spectroscopy of electron irradiated frozen oxygen and carbon dioxide mixtures with water

    Ozone has been detected on the surface of Ganymede via observation of the Hartley band through the use of ultraviolet spectroscopy and is largely agreed upon to be formed by radiolytic processing via interaction of magnetospheric energetic ions and/or electrons with oxygen-bearing ices on Ganymede's surface. Interestingly, a clearly distinct band near 300 nm within the shoulder of the UV-Vis spectrum of Ganymede was also observed, but currently lacks an acceptable physical or chemical explanation. Consequently, the primary motivation behind this work was the collection of UV-Vis absorption spectroscopy of ozone formation by energetic electron bombardment of a variety of oxygen-bearing ices (oxygen, carbon dioxide, water) relevant to this moon as well as other solar system. Ozone was indeed synthesized in pure ices of molecular oxygen, carbon dioxide and a mixture of water and oxygen, in agreement with previous studies. The Hartley band of the ozone synthesized in these ice mixtures was observed in the UV-Vis spectra and compared with the spectrum of Ganymede. In addition, a solid state ozone absorption cross section of 6.0 ± 0.6 × 10–17 cm2 molecule–1 was obtained from the UV-Vis spectral data. Ozone was not produced in the irradiated carbon dioxide-water mixtures; however, a spectrally 'red' UV continuum is observed and appears to reproduce well what is observed in a large number of icy moons such as Europa.

  9. Administration with Bushenkangshuai Tang alleviates UV irradiation- and oxidative stress-induced lifespan defects in nematode Caenorhabditis elegans

    Qi RUI; Qin LU; Dayong WANG

    2009-01-01

    During normal metabolism, oxidative bypro-ducts will inevitably generate and damage molecules thereby impairing their biological functions, including the is a traditional Chinese medicine widely used for clini-cally treating premature ovarian failure. In the present study, BT administration at high concentrations signifi-cantly increased lifespan, slowed aging-related decline, and delayed accumulation of aging-related cellular damage in wild-type Caenorhabditis elegans. BT admin-istration could further largely alleviate the aging defects induced by UV and oxidative stresses, and BT administra-tion at different concentrations could largely rescue the aging defects in mev-1 mutant animals. The protective effects of BT administration on aging process were at least partially dependent on the Ins/IGF-like signaling pathway. Moreover, BT administration at different concentrations obviously altered the expression patterns of antioxidant genes and suppressed the severe stress responses induced by UV and oxidative stresses, suggesting that BT-induced tolerance to UV or oxidative stress might result from reactive oxygen species scavenging. BT administration during development was not necessarily a requirement for UV and oxidative stress resistance, and the concentrations of administrated BT examined were not toxic for nematodes. Therefore, BT administration could effectively retrieve the aging defects induced by UV irradiation and oxidative stress in Caenorhabditis elegans.

  10. Reversible wettability of electron-beam deposited indium-tin-oxide driven by ns-UV irradiation

    Persano, Luana [NNL, National Nanotechnology Laboratory of CNR-Istituto Nanoscienze, Universita del Salento, via Arnesano, I-73100 Lecce (Italy); Center for Biomolecular Nanotechnologies UNILE, Istituto Italiano di Tecnologia, Via Barsanti, I-73010 Arnesano-LE (Italy); Del Carro, Pompilio [NNL, National Nanotechnology Laboratory of CNR-Istituto Nanoscienze, Universita del Salento, via Arnesano, I-73100 Lecce (Italy); Pisignano, Dario [NNL, National Nanotechnology Laboratory of CNR-Istituto Nanoscienze, Universita del Salento, via Arnesano, I-73100 Lecce (Italy); Center for Biomolecular Nanotechnologies UNILE, Istituto Italiano di Tecnologia, Via Barsanti, I-73010 Arnesano-LE (Italy); Dipartimento di Matematica e Fisica ' ' Ennio De Giorgi' ' , Universita del Salento, via Arnesano, I-73100 Lecce (Italy)

    2012-04-09

    Indium tin oxide (ITO) is one of the most widely used semiconductor oxides in the field of organic optoelectronics, especially for the realization of anode contacts. Here the authors report on the control of the wettability properties of ITO films deposited by reactive electron beam deposition and irradiated by means of nanosecond-pulsed UV irradiation. The enhancement of the surface water wettability, with a reduction of the water contact angle larger than 50 deg., is achieved by few tens of seconds of irradiation. The analyzed photo-induced wettability change is fully reversible in agreement with a surface-defect model, and it can be exploited to realize optically transparent, conductive surfaces with controllable wetting properties for sensors and microfluidic circuits.

  11. Mechanism of the clinical effects of uv-irradiated blood: stimulation of dna synthesis by human cells in culture

    This paper studies the DNA-synthetic activity of hyman embryonic cells (EC) cultured in the presence of supernatants from intact and irradiated cell fractions of blood or plasma. Human EC obtained from abortion material were incubated; after incubation, tritium-thymidine was added to the growth medium for 30 min. It is shown that stimulation of DNA synthesis in EC growing in the presence of supernatants from irradiated whole blood is not connected with photoactivation of growth factors in the blood plasma, but takes place as a result of their release from the cells. Donated blood, irradiated with UV light of the same wavelength and within the same dose range as are used under clinical conditions (up to 1200 J/m2), possesses growth-stimulating properties

  12. Reversible wettability of electron-beam deposited indium-tin-oxide driven by ns-UV irradiation

    Indium tin oxide (ITO) is one of the most widely used semiconductor oxides in the field of organic optoelectronics, especially for the realization of anode contacts. Here the authors report on the control of the wettability properties of ITO films deposited by reactive electron beam deposition and irradiated by means of nanosecond-pulsed UV irradiation. The enhancement of the surface water wettability, with a reduction of the water contact angle larger than 50 deg., is achieved by few tens of seconds of irradiation. The analyzed photo-induced wettability change is fully reversible in agreement with a surface-defect model, and it can be exploited to realize optically transparent, conductive surfaces with controllable wetting properties for sensors and microfluidic circuits.

  13. Effects of UV-ozone irradiation on copper doped nickel acetate and its applicability to perovskite solar cells.

    Kim, Jeongmo; Lee, Hee Ryung; Kim, Hyeong Pil; Lin, Tengda; Kanwat, Anil; Mohd Yusoff, Abd Rashid Bin; Jang, Jin

    2016-04-28

    The effects of UV-ozone (UVO) irradiation on copper-doped nickel acetate and its applicability to perovskite solar cells were investigated. UVO irradiation of copper-doped nickel acetate significantly increased the electrical conductivity (from 4.28 × 10(-4) S cm(-1) to 5.66 × 10(-2) S cm(-1)), which is due to the increased carrier concentration (from 3.53 × 10(13) cm(-3) to 2.41 × 10(16) cm(-3)), and the charge extraction efficiency was enhanced, leading to better compatibility with the hole transport layer. By UVO irradiation, the work function was increased from 4.95 eV to 5.33 eV by the surface dipole formation, which effectively reduced the interface barrier between the hole transport layer and the MAPbI3 light absorbing layer. UVO Irradiation of the underlying layer also allows the MAPbI3 precursors to form better morphology with highly arranged crystallinity. Compared to the cells using non-irradiated copper doped nickel acetate, UVO-irradiated copper-doped nickel acetate devices showed an enhanced open-circuit voltage (3% increase), short circuit current (16% increase), fill factor (5% increase), showing an enhanced power conversion efficiency of 12.2% (21% increase). PMID:27088187

  14. Role of solar conditioning in DNA repair response and survival of human epidermal keratinocytes following UV irradiation

    The authors have investigated the cumulative effects of sunlight exposure upon the excision-repair of UV radiation damage to DNA in epidermal keratinocytes from human donors of different ages as well as the possible effect on DNA repair of periodic conditioning of the cultured keratinocytes with sublethal UV radiation exposures. The authors have also compared the growth properties of UV-irradiated keratinocytes derived from habitually sun-exposed and nonexposed areas from the bodies of young and aged donors. DNA repair replication in keratinocytes from habitually sun-exposed facial skin and the less sun-exposed abdominal skin of middle-aged adults was found to be similar, with respect to both the UV dose response and the time course of repair after 20 J/m2, 254 nm. Growth and survival (after exposure up to 50 J/m2, 254 nm) were greater for keratinocytes from protected areas of the upper arm of young donors (under 18 years) than for cells from their own sun-exposed areas. Growth and survival were markedly reduced for all keratinocyte cultures from aged donors, especially those cultures developed from sun-exposed areas. Nevertheless, the DNA repair response to UV radiation was similar in all cases. The evident uncoupling of UV sensitivity from DNA repair capacity remains to be understood. These studies confirm that the cumulative effect of sunlight exposure indeed contributes to some skin aging processes. However, the authors have found no indication that an overall reduction in capacity for excision-repair of UV photoproducts in keratinocyte DNA accompanies senescence in human skin

  15. A general model to predict individual exposure to solar UV by using ambient irradiance data

    Vernez David; Milon Antoine; Vuilleumier Laurent; Bulliard Jean-Luc; Koechlin Alice; Boniol Mathieu; Doré Jean F.

    2015-01-01

    Excessive exposure to solar ultraviolet (UV) is the main cause of skin cancer. Specific prevention should be further developed to target overexposed or highly vulnerable populations. A better characterisation of anatomical UV exposure patterns is however needed for specific prevention. To develop a regression model for predicting the UV exposure ratio (ER, ratio between the anatomical dose and the corresponding ground level dose) for each body site without requiring individual measurements. A...

  16. Rapid transcriptome responses of maize (Zea mays) to UV-B in irradiated and shielded tissues

    Casati, Paula; Walbot, Virginia

    2004-01-01

    Background Depletion of stratospheric ozone has raised terrestrial levels of ultraviolet-B radiation (UV-B), an environmental change linked to an increased risk of skin cancer and with potentially deleterious consequences for plants. To better understand the processes of UV-B acclimation that result in altered plant morphology and physiology, we investigated gene expression in different organs of maize at several UV-B fluence rates and exposure times. Results Microarray hybridization was used...

  17. Dietary effect of royal jelly supplementation on epidermal levels of hydration, filaggrins, free amino acids and the related enzyme expression in UV irradiated hairless mice

    Ultraviolet (UV) irradiation reduces epidermal hydration, which is paralleled by the reduction of natural moisturizing factors (NMFs). Of various NMFs, free amino acids (AAs) are major constituents generated by filaggrin degradation. In this study, we attempted to determine whether dietary supplementation of royal jelly (RJ) in UV-irradiated mice can alters epidermal levels of hydration, filaggrins, and free AAs as well as of peptidylarginine deiminase-3 (PAD3), an enzyme involved in filaggrin degradation processes. Albino hairless mice were fed either a control diet (group UV+: UV irradiated control) or diets with 1% RJ harvested from different areas in Korea (groups RJ1, RJ2, and RJ3) or imported from China (group RJ4) for six weeks in parallel with UV irradiation. A normal control group (group UV-) was fed a control diet without UV irradiation for six weeks. Reduced epidermal levels of hydration, total filaggrins, and PAD3 were observed in group UV+; in group RJ1, these levels were increased to a level similar to that of group UV-. In addition, profilaggrins, two repeat intermediates (2RI), a precursor with two filaggrin repeats, and filaggrin were increased. Although no alteration of AAs was observed in any of the groups, and glutamate and serine, major AAs of NMF in group RJ1 were higher than in group UV+. Despite the increased levels of PAD3, epidermal levels of hydration, filaggrins, glutamate, and serine in groups RJ2, RJ3, and RJ4 were similar to those in group UV+. Dietary supplementation of RJ1 improves epidermal hydration in parallel with enhanced expression and degradation of filaggrin, but not by increased protein expression of PAD3, along with increased generation of glutamate and serine

  18. Photocatalytic decolorization of azo-dye with zinc oxide powder in an external UV light irradiation slurry photoreactor

    Photocatalytic decolorization of azo-dye Orange II in water has been examined in an external UV light irradiation slurry photoreactor using zinc oxide (ZnO) as a semiconductor photocatalyst. The effects of process parameters such as light intensity, initial dye concentration, photocatalyst loading and initial solution pH on the decolorization rate of Orange II have been systematically investigated. A two-stage photocatalytic decolorization of Orange II, the first stage of fast decolorization rate and the subsequent second stage of rather slow decolorization rate, was found. The efficiency of decolorization of Orange II increased as initial Orange II concentration decreased and UV light intensity increased. There was the optimal ZnO concentration being around 1000 mg L-1. The optimal pH was around 7.7, which was at the natural pH of the dye solution. The effect of aeration rate on the decolorization of Orange II has been also investigated and the enhancement of decolorization of Orange II with increasing aeration rate was found. By using a model for the light intensity profile in the external UV light irradiation slurry photoreactor, the simulation model for the decolorization of Orange II with ZnO photocatalyst has been developed. The proposed model in which the slow decolorization in the second stage as well as the initial fast decolorization is also taken into account could simulate the experimental results for UV light irradiation satisfactorily. The proposed simulation model in which the change of light intensity with time due to the decolorization of Orange II and the light scatter due to solid photocatalysts are considered will be very useful for practical engineering design of the slurry photoreactor of wastewater including textile dyes

  19. Mitochondrial DNA alterations of peripheral lymphocytes in acute lymphoblastic leukemia patients undergoing total body irradiation therapy

    2011-01-01

    Background Mitochondrial DNA (mtDNA) alterations, including mtDNA copy number and mtDNA 4977 bp common deletion (CD), are key indicators of irradiation-induced damage. The relationship between total body irradiation (TBI) treatment and mtDNA alterations in vivo, however, has not been postulated yet. The aim of this study is to analyze mtDNA alterations in irradiated human peripheral lymphocytes from acute lymphoblastic leukemia (ALL) patients as well as to take them as predictors for radiatio...

  20. Pathology of breast cancer in women irradiated for acute postpartum mastitis

    The gross and microscopic pathology of breast cancers in women irradiated for acute postpartum mastitis was compared to the breast cancers found in the sisters of the irradiated women. In considering the lesions in the two populations, the size, location, histologic type, histologic grade, inflammatory response, lymphatic and blood vascular invasion, nipple involvement, axillary lymph node metastases, and menopausal status at the time of diagnosis were statistically indistinguishable. The only parameter that was different in the two populations was the desmoplastic response to the malignant lesion. The control population had more marked fibrosis within the cancers compared with the irradiated women

  1. Reactivation of UV-irradiated plasmid transforming DNA by cells of yeast Saccharomyces cerevisiae

    Bekker, M.L.; Kozhina, T.N.; Smolina, V.S. (AN SSSR, Leningrad. Inst. Yadernoj Fiziki)

    1983-01-01

    Data revealing that cells of yeast Sccharomyces cerevisiae can reactivate transforming plasmid DNA after UV-radiation are given, this phenomenon at least partially depends on the system of exision reparation of master cells. Dependence of yeast survival rate and yield of yeast transformants on the UV-radiation dose of transforming DNA plasmid is disclosed.

  2. The effects of callus age, UV irradiation and incubation time on trans-resveratol production in grapevine callus culture

    In this study, the effects of callus age, ultraviolet (UV) irradiation and incubation time were investigated for the induction of trans-resveratrol production in callus cultures of Kalecik karası (Clone 12) Vitis vinifera L. grape cultivar. Part of leaves (~1 cm2) were taken from one year old grapevines grown in greenhouse and then were cultured in Gamborg B-5 media including 2% saccarose, 0.8% agar, 1.0 μM BAP (6-benzylaminopurine) and 0.1 μM 2, 4-D (2, 4-dichlorophenoxy-acetic acid). After the second subculture, 12 and 15 days old callus tissues were exposed to 254 nm UV light at 10 cm distance from the source for 10 and 15 min. Trans-resveratrol was measured at 0, 24, 48 and 72 hours of incubation by using High Pressure Liquid Chromatography (HPLC). Trans-resveratrol concentration of control callus ranged from 0.56 to 0.96 μg g fw-1. The highest trans-resveratrol production was obtained from 12 and 15 days-old callus irradiated for 10 min. at the 48th hours of incubation (2.42 μg g fw-1). Considering the highest value of trans-resveratrol concentration in controls and experiments, it was determined that UV irraditation in Kalecik karası elicitated the trans-resveratrol production by 2.5 times. (author)

  3. Solar UV radiation exposure of seamen – Measurements, calibration and model calculations of erythemal irradiance along ship routes

    Seamen working on vessels that go along tropical and subtropical routes are at risk to receive high doses of solar erythemal radiation. Due to small solar zenith angles and low ozone values, UV index and erythemal dose are much higher than at mid-and high latitudes. UV index values at tropical and subtropical Oceans can exceed UVI = 20, which is more than double of typical mid-latitude UV index values. Daily erythemal dose can exceed the 30-fold of typical midlatitude winter values. Measurements of erythemal exposure of different body parts on seamen have been performed along 4 routes of merchant vessels. The data base has been extended by two years of continuous solar irradiance measurements taken on the mast top of RV METEOR. Radiative transfer model calculations for clear sky along the ship routes have been performed that use satellite-based input for ozone and aerosols to provide maximum erythemal irradiance and dose. The whole data base is intended to be used to derive individual erythemal exposure of seamen during work-time.

  4. A case study on biomass burning aerosols: effects on solar UV irradiance, retrieval of aerosol single scattering albedo

    A. Bagheri

    2008-10-01

    Full Text Available The aerosol optical depth (AOD from biomass burning aerosols from eastern Europe was measured in Trondheim, Norway (63.43° N , 10.43° E in May 2006. The event was observed as far as the Arctic. In the first part of this paper, the surface measurements of direct and global UV radiation (and retrieved AOD are used to simulate the data using a radiative transfer model. Measured and simulated data were used to study the effect of biomass aerosol on the levels of surface UV radiation. We found reductions of up to 31%, 15% and 2% in direct, global and diffuse surface UV irradiance (at 350 nm, SZA=50°±0.5° as compared to typical aerosol conditions. In the second part of our study, surface measurements of global and direct irradiance at five wavelength in UVB and UVA (305, 313, 320, 340 and 380 nm were coupled with a radiative transfer model to produce values of aerosol single scattering albedo, ω. The aerosol single scattering albedo for biomass aerosols is compared to ω for background aerosols. The values of ω for biomass aerosols were 0.76 at 305 nm, 0.75 at 313 nm, 0.79 at 320 nm, 0.72 at 340 nm and 0.80 at 380 nm.

  5. Graft irradiation in the treatment of acute rejection of renal transplants: a randomized study

    A randomized study of graft irradiation in the treatment of acute rejection of renal transplants was conducted from 1978 to 1981. Patients developing clinical signs of an acute graft rejection received customary antirejection treatment in the form of intravenous administration of high-dose (1 gm per day) of methylprednisolone. They were at the same time randomized to either receive therapeutic irradiation (175 rad every other day to a total of 525 rad) or sham irradiation. Neither the patient nor the Transplant Service surgeons knew at any time whether the radiation treatment had been given. Eighty-three rejection episodes occurring in 64 grafts were entered into the study. Acute rejection was reversed in 84.5% of grafts in the control and 75% in the treated group. The incidence of recurrent rejection was higher in the treated group (66 vs. 46%) and graft survival was lower (22% vs. 54%). The study failed to demonstrate a beneficial effect of graft irradiation in the treatment of acute renal allograft rejection, when used in conjunction with high dose steriods

  6. Graft irradiation in the treatment of acute rejection of renal transplants: a randomized study

    Pilepich, M.V.; Anderson, C.B.; Etheredge, E.E.; Sicard, G.A.; Melzer, J.S.; Blum, J.

    1982-05-01

    A randomized study of graft irradiation in the treatment of acute rejection of renal transplants was conducted from 1978 to 1981. Patients developing clinical signs of an acute graft rejection received customary antirejection treatment in the form of intravenous administration of high-dose (1 gm per day) of methylprednisolone. They were at the same time randomized to either receive therapeutic irradiation (175 rad every other day to a total of 525 rad) or sham irradiation. Neither the patient nor the Transplant Service surgeons knew at any time whether the radiation treatment had been given. Eighty-three rejection episodes occurring in 64 grafts were entered into the study. Acute rejection was reversed in 84.5% of grafts in the control and 75% in the treated group. The incidence of recurrent rejection was higher in the treated group (66 vs. 46%) and graft survival was lower (22% vs. 54%). The study failed to demonstrate a beneficial effect of graft irradiation in the treatment of acute renal allograft rejection, when used in conjunction with high dose steriods.

  7. Investigation of the bystander effect in MRC5 cells after acute and fractionated irradiation in vitro

    Shokouhozaman Soleymanifard

    2014-01-01

    Full Text Available Radiation-induced bystander effect (RIBE has been defined as radiation responses observed in nonirradiated cells. It has been the focus of investigators worldwide due to the deleterious effects it induces in nonirradiated cells. The present study was performed to investigate whether acute or fractionated irradiation will evoke a differential bystander response in MRC5 cells. A normal human cell line (MRC5, and a human lung tumor cell line (QU-DB were exposed to 0, 1, 2, and 4Gy of single acute or fractionated irradiation of equal fractions with a gap of 6 h. The MRC5 cells were supplemented with the media of irradiated cells and their micronucleus frequency was determined. The micronucleus frequency after single and fractionated irradiation did not vary significantly in the MRC5 cells conditioned with autologous or QU-DB cell-irradiated media, except for 4Gy where the frequency of micronucleated cells was lower in those MRC5 cells cultured in the media of QU-DB-exposed with a single dose of 4Gy. Our study demonstrates that the radiation-induced bystander effect was almost similar after single acute and fractionated exposure in MRC5 cells.

  8. Preventive central nervous system irradiation in children with acute nonlymphocytic leukemia

    In this study of children with acute nonlymphocytic leukemia an attempt was made to prevent central nervous system relapse and to determine whether this therapy, coupled with multiagent chemotherapy, would be successful in prolonging durations of complete remission. Central nervous system relapses were prevented by irradiation, although patients who received this therapy did no better than those who did not receive irradiation. A small group of patients received irradiation to the liver and spleen, but this modality also failed to improve the duration of remission. Control of extramedullary leukemia, in this study, failed to improve remission duration because bone marrow relapse was not prevented or delayed. It is unlikely that focal therapy will have a significant impact in acute nonlymphocytic leukemia until longer marrow remissions are achieved

  9. Comparison of OMI ozone and UV irradiance data with ground-based measurements at two French sites

    V. Buchard

    2008-03-01

    Full Text Available Ozone Monitoring Instrument (OMI, launched in July 2004, is dedicated to the monitoring of the Earth's ozone, air quality and climate. OMI provides among other things the total column of ozone (TOC, the surface ultraviolet (UV irradiance at several wavelengths, the erythemal dose rate and the erythemal daily dose. The main objective of this work is to validate OMI data with ground-based instruments in order to use OMI products (collection 2 for scientific studies. The Laboratoire d'Optique Atmosphérique (LOA located in Villeneuve d'Ascq in the north of France performs solar UV measurements using a spectroradiometer and a broadband radiometer. The site of Briançon in the French Southern Alps is also equipped with a spectroradiometer operated by Interaction Rayonnement Solaire Atmosphère (IRSA. The instrument belongs to the Centre Européen Médical et Bioclimatologique de Recherche et d'Enseignement Supérieur. The comparison between the TOC retrieved with ground-based measurements and OMI TOC shows good agreement at both sites for all sky conditions. Comparisons of spectral UV on clear sky conditions are also satisfying whereas results of comparisons of the erythemal daily doses and erythemal dose rates for all sky conditions and for clear sky show that OMI overestimates significantly surface UV doses at both sites.

  10. Effect of in vitro and in vivo UV irradiation on the production of ETAF activity by human and murine keratinocytes

    Cultured epidermal cells and keratinocytes produce a potent hormone-like factor called epidermal cell-derived thymocyte-activating factor (ETAF). ETAF appears to be similar if not identical to a monocyte-derived lymphokine, known as interleukin 1 (IL-1). These two cytokines are able to amplify a diverse number of proliferative and inflammatory processes. Several recent investigations have suggested that UV-induced immunosuppression may be due in part to the inhibition of IL-1/ETAF production by monocytes and keratinocytes, respectively. We therefore decided to directly study the effects of various doses of in vitro and in vivo UV radiation (UVR) on the production of ETAF by normal murine epidermal cells and a murine (Pam 212) and a human (SCC) keratinocyte cell line. Our results surprisingly demonstrated an increase in both the extracellular and the intracellular ETAF activity of the murine epidermal, Pam 212, and SCC after sublethal amounts of in vitro UVR. Likewise, increased ETAF activity of murine epidermal cells was detected after sublethal doses of in vivo UVR. The UV-induced ETAF activity was cycloheximide-sensitive, suggesting that de novo synthesis of ETAF rather than cell membrane leakage was responsible for the increased ETAF activity. The fact that UV irradiation can increase ETAF activity by keratinocytes could have important local and systemic consequences for the host and may provide an efficient, contaminant-free method for generating ETAF activity for further biochemical and immunologic studies

  11. Supported Zinc Oxide Photocatalyst for Decolorization and Mineralization of Orange G Dye Wastewater under UV365 Irradiation

    Ming-Chin Chang

    2013-01-01

    Full Text Available To solve the environmental challenge of textile wastewater, a UV/ZnO photocatalytic system was proposed. The objective of this study was to prepare a photocatalytic system by utilizing both cold cathode fluorescent light (CCFL UV irradiation and steel mesh supported ZnO nanoparticles in a closed reactor for the degradation of azo dye C.I. Orange G (OG. Various operating parameters such as reaction time, preparation temperature, mixing speed, ZnO dosage, UV intensity, pH, initial dye concentration, and service duration were studied. Results presented efficient color and total organic carbon (TOC removal of the OG azo dye by the designed photocatalytic system. The optimal ZnO dosage for color removal was 60 g m−2. An alkaline pH of 11.0 was sufficient for photocatalytic decolorization and mineralization. The rate of color removal decreased with the increase in the initial dye concentration. However, the rate of color removal increased with the increase in the UV intensity. The steel mesh supported ZnO can be used repeatedly over 10 times without losing the color removal efficiency for 120 min reaction time. Results of Fourier transform infrared (FTIR and ion chromatography (IC indicated the breakage of N=N bonds and formation of sulfate, nitrate, and nitrite as the major and minor products. The observation indicated degradation of dye molecules.

  12. The Cellular Differences between Acute and Chronic Neutron and Gamma-Ray Irradiation in Mice

    Data on the shortening of the life span in mice by radiation show that an acute dose of gamma-rays may be as much as four times as effective as an equal dose of the same radiation administered chronically. However, for neutrons, chronic and acute administrations are equally effective. An analysis of these effects shows that for gamma-rays a certain fraction of the radiation injury is reparable, and that the value of this fraction depends on the dose and the dose rate. With neutrons, none of the damage appears reparable. For acute irradiation, the RBE is about 2 for shortening of the life span, but for chronic, may be as high as 8. Chromosome aberrations have been scored in liver cells of mice when treated with both chronic and acute doses of both gamma-rays and thermal neutrons. In all cases the percentage of aberrent cells is proportional to the shortening of the life span produced by the treatment. Further, with neutrons, acute and chronic irradiation is equally effective in producing chromosome abberations. For gamma-rays, acute irradiation may produce as much as four times the chromosomal damage as does chronic irradiation. This shows that some chromosomes can heal themselves following small doses of gamma-rays, but there is no chromosome healing following any dose of neutrons. The RBE using chromosome aberrations as a criterion is the same as for life shortening. These results give a firm cellular basis for the known biological differences between gamma rays and neutrons, and in addition give strong support to the concept that natural and radiation-induced aging are caused by spontaneous and radiation-induced mutations, respectively, in the somatic cells of animals. (author)

  13. Tentative therapy of acute abdominal irradiations of pigs

    The anatomical and physiological considerations that make pig an interesting experimental model for radiobiological investigations are first reviewed. The anatomo- and physico-pathological bases of therapy acute abdominal exposure are stated, especially the kinetics and limits of intestinal recovery at various doses. A therapeutic procedure is given and the experimental results on reanimation (parenteral alimentation), re-nutrition (continuous enteral infusion) and intestine grafts are presented

  14. Micro-Raman and UV-VIS Studies of 100 MeV Ni4+ Irradiated Cadmium Telluride Thin Films

    Neelam Pahwa

    2011-01-01

    Full Text Available CdTe thin films grown by thermal evaporation on quartz substrates were irradiated with Swift (100 MeV Ni 4 + ions for fluences in the range 1.0 × 1011 - 1.0 × 1013 cm – 2. The modification in the structure and optical properties has been studied as a function of ion fluence using Micro-Raman spectroscopy and UV-VIS spectroscopy. In Micro Raman spectrum, weak LO and TO modes of CdTe and A1 & E modes of Te were observed with blue shift which was found to increase with increase in fluence. Intensity of these modes decreased with increase in ion fluence. UV-transmission showed pronounced interference fringes, indicating a good quality of the films. The bandgap was found to increase in the range 1.4-1.75 eV with increase in fluence.

  15. The role of plasma lipid photo-oxidation in the decrease of the aggregation of platelets under UV irradiation

    Change of platelet aggregation dependent on blood plasma under irradiation of plasma enriched with platelets and serium (1) as well as the role of peroxide photooxidation on non-saturated fatty acids (2) have been studied. Based on the obtained data it is concluded that peroxide photooxidation and stimulation of dark oxidation of their lipids under UV-radiation effect on blood plasma or serium. Products of these reactions weaken aggregation of platelets suspended in serum (plasma). Platelets destroy products of peroxide oxidation of plasma lipids, and as a result aggregation of cells is gradually reduced under incubation of platelet and plasma mixture irradiatted in darkness. It is supposed that photooxidation of blood lipids produces curative properties to blood under UV-radiation

  16. Induction of mutations in blue-green alga Anacystis nidulans by consolidated and split UV irradiation

    Ultraviolet mutability of consolidated and split dose treatment in A. nidulans was investigated with reference to induction of phage- and streptomycin-resistant markers. The consolidated UV treatment induced both the markers about 100-150-fold, whereas under photoreactivating conditions the survival of alga was enhanced and mutation frequency was decreased. The split UV treatment with 6 hr dark incubation between two UV exposures enhanced the survival and mutation frequencies to 500-700 fold above the back-ground level. The data give indirect evidence for the presence of error-prone dark repair system in this organism. (auth.)

  17. Modulation of in vitro transformation and the early and late modes of DNA replication of uv-irradiation Syrian hamster cells by caffeine

    The effect of caffeine on post-uv DNA replication was studied to determine its relevance to carcinogenesis. The level of uv-induced transformed colonies of Syrian hamster embryo cells (HEC) was increased up to fivefold when caffeine was added to cells between 0 and 6 h post-uv. The greatest increase was observed when the interval between uv irradiation and caffeine addition was 4 h. Two modes of DNA replication occurred after uv irradiation. During the early mode (0 to 3 h post-uv) the size of nascent strands, as measured by alkaline sucrose sedimentation, was smaller than those in nonirradiated cells, whereas during the late mode they recovered to normal size. Caffeine inhibited the rate of elongation of nascent strands during the early mode. When caffeine was added immediately after uv irradiation, the conversion of the early mode to the late mode was inhibited. Studies on the effects of caffeine have now been extended to the late mode. While caffeine has little effect with the fd elements beginning from the 10th day after irradiation is connected with their proliferation but not with the migration out from lymphoid organs

  18. Effects of osteoblasts on recovery of hematopoiesis and angiogenesis in acute irradiation injured mice

    Objective: To explore the effects of osteoblasts on the recovery of hematopoiesis and angiogenesis in acute irradiation injury mice. Methods: The femurs of 18 male BALB/c mice were used to prepare the bone marrow osteoblasts, and the rest mice were divided into 3 groups as normal group, saline group and osteoblast group. The mice in normal group received no treatment, and the other two groups were received 6.0 Gy 60Co γ-ray irradiation. After irradiation each mouse of osteoblast group was administered with 2 × 106 osteoblasts through tail vein injection, and equal volume saline was given to each mouse of saline group by the same way. The following factors were measured at 7, 14, 21 d after irradiation, they were the counts of peripheral blood cells and bone marrow mononuclear cells (BMMNC), the percentage of CD34 + cells in BMMNC, the histology changes and micro vascular density (MVD) of bone marrow tissue. Results: The counts of peripheral blood cells, BMMNC and hematopoietic tissue area in osteoblast group were higher than those in saline group.The percentage of CD34 + cells in BMMNC and the MVD of bone marrow in osteoblast group were also higher than those in saline group at 7, 14, 21 d after irradiation (t=2.46-64.51, P<0.05). Conclusions: Osteoblasts could significantly promote the recovery of hematopoiesis and angiogenesis in mice after acute irradiation injury. (authors)

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

    The formation of regulated and emerging halogenated carbonaceous (C-) and nitrogenous disinfection by-products (N-DBPs) from the chlor(am)ination and UV irradiation of tyrosine (Tyr) was investigated. Increased chlorine contact time and/or Cl2/Tyr ratio increased the formation of most C-DBPs, with the exception of 4-chlorophenol, dichloroacetonitrile, and dichloroacetamideChloroform and dichloroacetic acid increased with increasing pH, dichloroacetonitrile first increased and then decreased, and other DBPs had maximum yields at pH 7 or 8. The addition of ammonia significantly reduced the formation of most C-DBPs but increased 4-chlorophenol, dichloroacetonitrile, dichloroacetamide, and trichloroacetonitrile yields for short prechlorination contact times before dosing ammonia. When UV irradiation and chlorination were performed simultaneously, the concentrations of the relatively stable C-DBPs increased, and the concentrations of dichloroacetonitrile, dichloroacetamide, and 4-chlorophenol decreased with increasing UV dose. This information was used to develop a mechanistic model for the formation of intermediate DBPs and end products from the interaction of disinfectants with tyrosine. Highlights: ► Increased contact time and/or Cl2/Tyr decreased the formation of some N-DBPs. ► Changing the pH of disinfection decreases the formation of some N-DBPs. ► N-DBP yields increased for short prechlorination contact time before dosing ammonia. ► Low pressure UV before chlorination did not impact the formation of DBPs from Tyr. ► A novel integrated formation pathway of halogenated C-, N-DBPs is proposed. - Exploring the integrated formation mechanism of regulated and emerging highly toxic DBPs, which is expected to preferably reduce their occurrence in drinking water.

  20. Selective adsorption of thiophenic compounds from fuel over TiO2/SiO2 under UV-irradiation.

    Miao, Guang; Ye, Feiyan; Wu, Luoming; Ren, Xiaoling; Xiao, Jing; Li, Zhong; Wang, Haihui

    2015-12-30

    This study investigates selective adsorption of thiophenic compounds from fuel over TiO2/SiO2 under UV-irradiation. The TiO2/SiO2 adsorbents were prepared and then characterized by N2 adsorption, X-ray diffraction and X-ray photoelectron spectroscopy. Adsorption isotherms, selectivity and kinetics of TiO2/SiO2 were measured in a UV built-in batch reactor. It was concluded that (a) with the employment of UV-irradiation, high organosulfur uptake of 5.12 mg/g was achieved on the optimized 0.3TiO2/0.7SiO2 adsorbent at low sulfur concentration of 15 ppmw-S, and its adsorption selectivity over naphthalene was up to 325.5; (b) highly dispersed TiO2 served as the photocatalytic sites for DBT oxidation, while SiO2 acted as the selective adsorption sites for the corresponding oxidized DBT using TiO2 as a promoter, the two types of active sites worked cooperatively to achieve the high adsorption selectivity of TiO2/SiO2; (c) The kinetic rate-determining step for the UV photocatalysis-assisted adsorptive desulfurization (PADS) over TiO2/SiO2 was DBT oxidation; (d) consecutive adsorption-regeneration cycles suggested that the 0.3TiO2/0.7SiO2 adsorbent can be regenerated by acetonitrile washing followed with oxidative air treatment. This work demonstrated an effective PADS approach to greatly enhance adsorption capacity and selectivity of thiophenic compounds at low concentrations for deep desulfurization under ambient conditions. PMID:26223016

  1. Photoionization behavior of Eu2+-doped BaMgSiO4 long-persisting phosphor upon UV irradiation

    Highlights: → Photoionization behavior of BaMgSiO4:Eu2+ long persistent phosphor upon UV irradiation. → Green phosphorescence was obtained from BaMgSiO4:Eu2+. → The ionization of Eu2+ to Eu3+ was observed in BaMgSiO4:Eu2+. → The photogenerated Eu3+ cannot change back to its divalent state at room temperature. → The phosphorescence is associated with the formation forming Eu3+-e- pairs. - Abstract: The fluorescence, phosphorescence and thermoluminescence properties of Eu-doped BaMgSiO4 phosphors sintered in air and in a reducing atmosphere were investigated. Phosphorescence of phosphor sintered in a reducing atmosphere can last for 1.5 h at a recognizable intensity level, whereas phosphorescence of air-sintered phosphor can only persist for 6 min. In addition, a distinction between the shape of the fluorescence spectrum and its corresponding phosphorescence spectrum is observed in the former case. Ionization of Eu2+ to Eu3+ upon UV irradiation is observed in the phosphor prepared in a reducing atmosphere, but there is no indication that the photogenerated Eu3+ cannot change back to its divalent state at room temperature after the excitation source is switched off. In addition, phosphor sintered in a reducing atmosphere shows photochromism upon UV irradiation. No such photoionization and photochromism behavior is observed for the air-sintered phosphor. A possible Eu2+ photoionization mechanism is constructed on the basis of these experimental observations. The photoionization mechanism presented can also successfully explain the fluorescence and phosphorescence behavior of Eu in BaMgSiO4.

  2. Effect of UV irradiation on Echinaceae purpureae interactions with free radicals examined by an X-band (9.3 GHz) EPR spectroscopy

    Ramos, Paweł; Pilawa, Barbara

    2014-01-01

    The effect of UVA (315–400 nm) irradiation on Echinaceae purpureae interactions with free radicals was examined by the use of electron paramagnetic resonance (EPR) spectroscopy. The changes of antioxidant properties of E. purpureae with time of UV irradiation from 10 to 110 min (10 min steps) were determined. DPPH as the paramagnetic reference was used in this study. Changes of EPR signals of the reference after interactions with nonirradiated and UV-irradiated E. purpureae were detected. Int...

  3. UV-irradiation of blood as method for increasing animal resistance

    Influence of the irradiated autoblood on animal resistance and productivity indices was studied in heifers at the age of 10 days to 3 monthes. During this period reinfusion of the irradiated blood was conducted 52 times. The procedure is described in detail. Clinicophysiologic, hematologic, biochemical and immunologic investigations were conducted with heifers. It is established, that reinfusion of the irradiated autoblood affects essentially the indices studied. Positive effect on lactation and productivity is pointed out as well

  4. Green synthesis of silver/montmorillonite/chitosan bionanocomposites using the UV irradiation method and evaluation of antibacterial activity

    Kamyar Shameli

    2010-10-01

    Full Text Available Kamyar Shameli1, Mansor Bin Ahmad1, Wan Md Zin Wan Yunus1, Abdolhossein Rustaiyan2, Nor Azowa Ibrahim1, Mohsen Zargar3, Yadollah Abdollahi41Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, Serdang, Selangor, Malaysia; 2Department of Chemistry, Science and Research Campus, Islamic Azad University, Tehran, Iran; 3Faculty of Food Science and Biotechnology, 4Institute of Advanced Technology, Universiti Putra Malaysia, Serdang, Selangor, MalaysiaAbstract: In this study, silver nanoparticles (Ag-NPs were synthesized using a green physical synthetic route into the lamellar space of montmorillonite (MMT/chitosan (Cts utilizing the ultraviolet (UV irradiation reduction method in the absence of any reducing agent or heat treatment. Cts, MMT, and AgNO3 were used as the natural polymeric stabilizer, solid support, and silver precursor, respectively. The properties of Ag/MMT/Cts bionanocomposites (BNCs were studied as the function of UV irradiation times. UV irradiation disintegrated the Ag-NPs into smaller sizes until a relatively stable size and size distribution were achieved. Meanwhile, the crystalline structure and d-spacing of the MMT interlayer, average size and size distribution, surface morphology, elemental signal peaks, functional groups, and surface plasmon resonance of Ag/MMT/Cts BNCs were determined by powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray fluorescence, Fourier transform infrared, and UV-visible spectroscopy. The antibacterial activity of Ag-NPs in MMT/Cts was investigated against Gram-positive bacteria, ie, Staphylococcus aureus and methicillin-resistant S. aureus and Gram-negative bacteria (ie, Escherichia coli by the disk diffusion method on Muller–Hinton Agar at different sizes of Ag-NPs. All of the synthesized Ag/MMT/Cts BNCs were found to have high antibacterial activity. These results show that Ag/MMT/Cts BNCs can be useful in different

  5. Comparison of UV irradiation and p-fluorphenylaline as selective agents for production of aromatic compounds in plant cell culture

    Resistance to UV irradiation, and to the toxicity of p-fluorophenylalanine, can both be mediateted in plants by enhanced synthesis of aromatic compounds. These selective agents were applied to cell cultures of Nicotiana tabacum, Anchusa officinalis and Catharanthus roseur, and the production of aromatic metabolites in the resulting resistant lines of each species was compared. While Nicotiana and Anchusa cultures responded to each selective agent ith an enhanced accumulation of aromatic compounds, the Catharanthus cultures acquired resistance through other, unknown, mechanisms. Some degree of cross-resistance was observed between cultures selected individually for resistance to each agent (author). 26 refs.; 2 figs.; 1 tab

  6. Excision repair and patch size in UV-irradiated bacteriophage T4.

    Yarosh, D B; Rosenstein, B S; Setlow, R B

    1981-01-01

    We determined the average size of excision repair patches in repair of UV lesions in bacteriophage T4 by measuring the photolysis of bromodeoxyuridine incorporated during repair. The average patch was small, approximately four nucleotides long. In control experiments with the denV1 excision-deficient mutant, we encountered an artifact, a protein(s) which remained bound to phenol-extracted DNA and prevented nicking by the UV-specific endonucleases of Micrococcus luteus and bacteriophage T4.

  7. Effect of UV-irradiation in vitro on adenin nucleotides metabolism, Na+ and K+ concentration, osmotic properties and submicroscopic structure of pigeon red blood cells

    Effect of UV-irradiation in vitro on metabolism of adenine nucleotides: ADP, ATP and AXP, osmotic properties and submicroscopic structure of nucleated pigeon red blood cell was investigated. Irradiation was carried out for 60, 120, 180, 240 and 300 minutes. Hanau S-500 lamp with efficiency 4.34 x 108 erg/sec was used. A decrease of ATP content with a simultaneous increase of ADP and AXP contents and a rather constant level of the sum of adenine compounds was observed. UV-irradiation caused a decrease of reversal of hemolysis and osmotic resistance to hypotonic NaCl solutions. An equivalent exchange of Na+ and K+ ions and an increase of hematocrit value, following UV-irradiation was observed. Electron microscope studies demonstrated changes of ultrastructure concerning both cell nucleus and thickness and granulation of cell membrane. (orig.)

  8. Studies on the effect of UV irradiation on Mn-doped ZnS nanoparticles

    With the advent of the increased attraction in compound semiconductors, attention has been focused on the research involving nanocrystalline Mn2+ doped ZnS (ZnS : Mn). In this paper, nano-scaled ZnS : Mn (both unpassivated and pasivated samples) was synthesized and we report the photoacoustic (PA) as well as photoluminescence (PL) properties upon exposure to ultraviolet (UV) light. It was found that passivation with acrylic acid (AA) yielded higher photoluminescence intensity. UV exposure caused a decrease in the PA intensity observed owing to a decrease in the nonradiative processes during exposure. A corresponding increase in the radiative processes was verified with the increase in the PL intensity during UV exposure. These experimental results suggest the possibility of UV curing for the passivating AA monomer and photochemical reactions around the nanocrystals, indicating the increase of the fluorescence quantum efficiency. Luminescent time decay measurements for the sample without AA showed a lengthening in the time decay constant after UV exposure. On the other hand, for the sample with AA, no change in the time decay constants was observed. This further strengthens the theory that during UV exposure, different luminescent decay mechanisms exist for the unpassivated and passivated samples

  9. Acute radiation syndrome, c.aused by single whole-body external irradiation

    The general characteristic of conceptions of the material substrate of various forms and types of radiation injuries from the moment of a wide use of radiation energy and radioactive substances up to the present time, the dependence of structural changes on the type of ionizing radiation, dose and forms of its effect, are presented. The pathological anatomy of particular manifestations of acute radiation disease in various systems of the organism is described. The attention is paid to the variant of radiation disease taking place during non-uniform general irradiation. Local and general morphological changes which develop in skin, hyperdermic fat and skeleton muscles simultaneously in the zone of massive local effect against the background of the general radiation injury, are described for the first time. Delayed alterations in blood vessels and interstitial tissue after the acute radiation disease are described as well as the pathomorphology and histochemistry of trophic disorders in the acute and delayed periods of acute radiation disease

  10. Effects of UV-ozone irradiation on copper doped nickel acetate and its applicability to perovskite solar cells

    Kim, Jeongmo; Lee, Hee Ryung; Kim, Hyeong Pil; Lin, Tengda; Kanwat, Anil; Mohd Yusoff, Abd. Rashid Bin; Jang, Jin

    2016-04-01

    The effects of UV-ozone (UVO) irradiation on copper-doped nickel acetate and its applicability to perovskite solar cells were investigated. UVO irradiation of copper-doped nickel acetate significantly increased the electrical conductivity (from 4.28 × 10-4 S cm-1 to 5.66 × 10-2 S cm-1), which is due to the increased carrier concentration (from 3.53 × 1013 cm-3 to 2.41 × 1016 cm-3), and the charge extraction efficiency was enhanced, leading to better compatibility with the hole transport layer. By UVO irradiation, the work function was increased from 4.95 eV to 5.33 eV by the surface dipole formation, which effectively reduced the interface barrier between the hole transport layer and the MAPbI3 light absorbing layer. UVO Irradiation of the underlying layer also allows the MAPbI3 precursors to form better morphology with highly arranged crystallinity. Compared to the cells using non-irradiated copper doped nickel acetate, UVO-irradiated copper-doped nickel acetate devices showed an enhanced open-circuit voltage (3% increase), short circuit current (16% increase), fill factor (5% increase), showing an enhanced power conversion efficiency of 12.2% (21% increase).The effects of UV-ozone (UVO) irradiation on copper-doped nickel acetate and its applicability to perovskite solar cells were investigated. UVO irradiation of copper-doped nickel acetate significantly increased the electrical conductivity (from 4.28 × 10-4 S cm-1 to 5.66 × 10-2 S cm-1), which is due to the increased carrier concentration (from 3.53 × 1013 cm-3 to 2.41 × 1016 cm-3), and the charge extraction efficiency was enhanced, leading to better compatibility with the hole transport layer. By UVO irradiation, the work function was increased from 4.95 eV to 5.33 eV by the surface dipole formation, which effectively reduced the interface barrier between the hole transport layer and the MAPbI3 light absorbing layer. UVO Irradiation of the underlying layer also allows the MAPbI3 precursors to form

  11. Both membrane-dependent and DNA damage-dependent signal transduction chains are activated following UV irradiation

    Irradiation of cultured cells with short wave length ultraviolet light (UVC) activates at least two types of signal transduction chains which ultimately lead to changes in gene expression. One type involves cell surface receptors and is activated with very rapid kinetics. One or several membrane associated protein tyrosine phosphatases are inhibited in less than one minute following UV exposure. Consequently the dephosphorylation of tyrosine-phosphorylated growth factor receptors is impaired. This process is ligand-independent and suggests spontaneous autophosphorylation activity of receptor tyrosine kinases. The UV-induced auto-phosphorylations trigger-signal transduction to the nucleus and activate transcription of immediate early genes such as c-fos. The other type of signal transduction chain has its origin in DNA damage. It occurs with delayed kinetics. We analyzed several human fibroblastic cell lines with distinct deficiencies in nucleotide excision repair mechanisms for the dose dependence of UV-induced late appearing and stable collagenase I mRNA. Several cell lines with deficiencies in the preferential repair of transcribed genes required lower doses of UV than wild type cells or cells solely deficient in the repair of the overall genome. These data suggest the existence of a signal transduction cascade whose stimulation is elicited by lesions in transcribed genes. It appears that similar or identical transcription factors are activated by both types of UV-induced signal transduction. For instance the transcription factor NFκB is activated by both, a DNA damage independent and a DNA damage dependent signal transduction chain. (authors)

  12. Preferential synthesis of low-molecular-weight RNA in uv-irradiated plasma of Physarum polycephalum

    Kumari, P.A.V.; Nair, V.R.

    1981-10-01

    Mitotically synchronous surface plasmodia of Physarum polycephalum were irradiated during the G2 phase with a Philips 15-W germicidal lamp. At different intervals after irradiation, the plasmodia were pulse-labeled with (/sup 3/H)uridine, and RNA was extracted and analyzed on linear sucrose gradients. The radioactivity profiles of the RNA showed that irradiated plasmodia synthesize preferentially low-molecular-weight RNA types, including 4 SRNA, during the delay period prior to the first postirradiation mitosis and during the following short mitotic cycle. Double-labeling experiments, employing (/sup 14/C)uridine-prelabeled plasmodia which were pulse-labeled with (/sup 3/H)uridine after irradiation, confirmed this finding. It is also seen that there is an overall reduction in the rate of synthesis of rRNA in the irradiated plasmodia.

  13. Study on the surface chemical properties of UV excimer laser irradiated polyamide by XPS, ToF-SIMS and CFM

    Polyamide (nylon 6) was irradiated by a pulsed ultraviolet (UV) excimer laser with a fluence below its ablation threshold. Chemical modifications on laser treated nylon were studied by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (Tof-SIMS) and chemical force microscopy (CFM). XPS study provides information about changes in chemical composition and the chemical-state of atom types on the fiber surface. The high sensitivity of ToF-SIMS to the topmost layers was used to detect crosslinking after the laser treatment. Gold-coated AFM tips modified with -COOH terminated self-assembled alkanethiol monolayers (SAMs) were used to measure adhesion forces on the untreated and laser treated samples. XPS results revealed that the irradiated samples have higher oxygen content than prior to laser irradiation. Tof-SIMS analysis illustrated that carbonyl groups in nylon 6 decrease significantly but hydroxyl groups increase after low-fluence laser irradiation. The adhesion force measurements by CFM showed spatial distribution of hydroxyl groups on nylon 6 after the laser treatment

  14. Study on the surface chemical properties of UV excimer laser irradiated polyamide by XPS, ToF-SIMS and CFM

    Yip, Joanne; Chan, Kwong; Sin, Kwan Moon; Lau, Kai Shui

    2003-01-01

    Polyamide (nylon 6) was irradiated by a pulsed ultraviolet (UV) excimer laser with a fluence below its ablation threshold. Chemical modifications on laser treated nylon were studied by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (Tof-SIMS) and chemical force microscopy (CFM). XPS study provides information about changes in chemical composition and the chemical-state of atom types on the fiber surface. The high sensitivity of ToF-SIMS to the topmost layers was used to detect crosslinking after the laser treatment. Gold-coated AFM tips modified with COOH terminated self-assembled alkanethiol monolayers (SAMs) were used to measure adhesion forces on the untreated and laser treated samples. XPS results revealed that the irradiated samples have higher oxygen content than prior to laser irradiation. Tof-SIMS analysis illustrated that carbonyl groups in nylon 6 decrease significantly but hydroxyl groups increase after low-fluence laser irradiation. The adhesion force measurements by CFM showed spatial distribution of hydroxyl groups on nylon 6 after the laser treatment.

  15. Clinical analysis of patients with acute radiation syndrome due to total body irradiation or total lymphatic irradiation

    Objective: To study the severity of iatrogenic acute radiation syndrome, treatment, hematopoietic recovery and related complications in patients subjected to total body irradiation (TBI) or total lymphatic irradiation (TLI) prior to hematopoietic stem cell transplantation. Methods: 100 tumor patients (91 with leukemia and 9 with other tumors), after receiving 500∼1000 cGy (in an average of 738.6 cGy) of TBI or TLI with super high dose chemotherapy as conditioning regimen during the process of hemopoietic stem cell transplantation, developed severe or even extremely severe, mainly bone marrow form acute radiation syndrome. Results: The patients' white blood cell count once dropped to (0∼0.15) x 109/L, platelet count fell to (1∼17) x 109/L, bone marrow was depleted with only a few non-hemopoietic cells and rare hemopoietic cells, and a high risk of complicating with infection and hemorrhage was observed. Treated with a variety of measures including protective isolation, supportive care, administration of growth factors such as GM-CSF or G-CSF, blood component transfusion and effective antibiotics, 92 cases restored their normal hemopoiesis, while 8 cases died of infection or hemorrhage. The clinical course of these patients indicated that a majority of the patients with severe and extremely severe, iatrogenic acute radiation syndrome involving bone marrow could restore their normal hemopoiesis, and hemopoietic stem cell transplantation played an important role in the treatment. Conclusion: Hemopoietic stem cell transplantation and administration of growth factors are very useful for the treatment of acute radiation syndrome

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

    W. Gurlit

    2004-12-01

    Full Text Available Within the framework of the ENVISAT/-SCIAMACHY satellite validation, solar irradiance spectra are absolutely measured at moderate resolution in the UV/visible spectral range (in the UV from 316.7–418 nm and the visible from 400–652 nm at a full width half maximum resolution of 0.55 nm and 1.48 nm, respectively from aboard the azimuth-controlled LPMA/DOAS balloon gondola at around 32 km balloon float altitude. After accounting for the atmospheric extinction due to Rayleigh scattering and gaseous absorption (O3, and NO2, the measured solar spectra are compared with previous observations. Our solar irradiance is +1.6% larger than the re-calibrated Kurucz et al. (1984 solar spectrum (Fontenla et al., 1999, called MODTRAN 3.5 in the visible spectral range (435–650 nm, +1.5% larger in the (370–415 nm wavelength interval, but −4% smaller in the UV spectral range (316.7–370 nm, when the Kurucz spectrum is convolved to the spectral resolution of our instrument. The same comparison with the SOLSPEC solar spectrum (Thuillier et al., 1997, 1998a, b confirms the somewhat larger solar irradiance (+1.7% measured by the balloon instrument from 435–500 nm, but not from 500–650 nm, where the SOLSPEC is −1.3% lower than MODTRAN 3.5. Comparison of the SCIAMACHY solar spectrum from channels 1 to 4 (– re-calibrated by the University of Bremen – with MODTRAN 3.5 indicates an agreement of +0.2% in the visible spectral range (435–585 nm. With this calibration, the SCIAMACHY solar spectrum is congruent with the balloon observations (−1% in the 316.7–370 nm wavelength range, but both are up to −5%/−3% smaller than MODTRAN 3.5 and SOLSPEC, respectively. In agreement with findings of Skupin et al. (2002 our study emphasizes that the present ESA SCIAMACHY level 1 calibration is systematically +15% larger in the considered wavelength intervals when compared to all available other solar irradiance measurements.

  17. Acute irradiation and muscular fibrosis. Development and characteristics in the pig

    This study was performed in an experimental porcin model of acute local irradiation chosen to simulate human accidents. It enabled to determine the development and the physiopathological characteristics of the fibrous tissue which developed in skeletal muscle. In the first month after irradiation the strong inflammatory reaction initiating the radiation induced fibrosis was characterized by edema as visualized on NMR imaging and by acute phase reactant protein changes, associated with elevations of local and general temperatures in irradiated animals. At the margin of the irradiated tissue, atypical fibroblasts isolated among collagen bundles or bunched in nodullary reinforcement were seen associated with intense capillary neogenesis. Several months after irradiation normal skeletal muscle was replaced by atrophic fibrosis delimited by an inflammatory perifibrotic tissue. The muscular fibrosis was characterized by a high atypical fibroblasts density and by an inflammatory distribution pattern of collagen types I, III, IV, laminin, fibronectin and fibrinogen as visualized by immunohistochemical methods. Biochemical results showed an increase in collagen content and synthesis in fibrotic tissue whereas perifibrotic zone synthesized more non collagenous proteins compared with the normal muscle. The contributions of granulation tissue, cellular mediators and inhibition of muscular regeneration to maintain the atrophic character of the muscular radiation induced fibrosis are discussed

  18. Effect of Acute and Chronic Gamma Irradiation on in vitro Growth of Stevia rebaudiana Bertoni

    Stevia rebaudiana Bertoni is a perennial herb that belongs to the family of Asteraceae. It is a natural sweetener plant known as sweet leaf, which is estimated to be 300 times sweeter than cane sugar. In this study, micropropagation and in vitro mutagenesis of this natural herb was successfully conducted. It was found that shoot tips on MS medium supplemented with 1 mg/l Kinetin showed the highest shoot induction and multiplication after 3 weeks of culture. Radiosensitivity test was conducted to identify the LD50 for in vitro stevia shoots and to select effective doses to be used for the in vitro mutagenesis. Shoot tips were irradiated with acute and chronic gamma radiation at 0, 10.00, 20.00, 30.00, 40.00, 60.00, and 80.00 Gy. At 60 Gy and 80 Gy, the shoot tips demonstrated 0 % survival, all were killed. LD50 for stevia (the dose that killed 50 % of the irradiated explants) was at 29 Gy. In this study, LD 50 for the stevia (the dose that killed 50 % of the irradiated explants) was at 29 Gy for acute irradiation and was at 45 Gy for chronic irradiation. The effective doses were selected at 10, 20 and 30 Gy. These three selected doses were applied for the in vitro mutagenesis of the stevia shoots. (author)

  19. Acute effects of whole body gamma irradiation on exocrine pancreatic secretion in the pig

    Reports on radiation damage to the pancreas deal essentially with long-term morphological changes with few data on pancreatic exocrine function. The aim of this work was to study the acute effects of whole body irradiation on volume and enzyme activities in the pancreatic juice. A whole body gamma irradiation (6 Gy) was investigated in pigs with continuous sampling of pancreatic juice before and after exposure via an indwelling catheter in the pancreatic duct. For each sample collected, total protein concentration and enzyme activities of trypsin, chymotrypsin, elastase, lipase and amylase were determined. Pancreatic juice volume was monitored during all periods of collection. The volume of pancreatic juice secreted daily decreased one day after irradiation and remained lower than the control values over the experimental period. Total proteins secreted in the pancreatic juice and total activities of pancreatic enzymes were reduced similarly. On the other hand, only specific activities of elastase and lipase were affected by irradiation. Whole body gamma irradiation resulted in a rapid and marked decrease of exocrine pancreatic secretion, in terms of volume as well as secreted enzymes. This may contribute in part to the intestinal manifestations of the acute and/or late radiation syndrome. (author)

  20. Replication of simian virus 40 DNA after UV irradiation: evidence of growing fork blockage and single-stranded gaps in daughter strands

    The molecular mechanisms of in vivo inhibition of mammalian DNA replication by exposure to UV light (at 254 nm) was studied in monkey and human cells infected with simian virus 40. Analysis of viral DNA by electron microscopy and sucrose gradients confirmed that the presence of UV-induced lesions severely blocks DNA synthesis, and thus the conversion of replicative intermediates (RIs) into fully replicated form I DNA is inhibited by UV irradiation. These blocked RI molecules present several special features when visualized by electron microscopy. In excision repair-proficient monkey and human cells they are composed of a double-stranded circular DNA with a double-stranded tail whose size corresponds to the average interpyrimidine dimer distance, as determined by the dimer-specific T4 endonuclease V. In excision repair-deficient human cells from patients with xeroderma pigmentosum, UV-irradiated RIs present a Carins-like structure similar to that observed for replicating molecules obtained from unirradiated infected cells. Single-stranded gaps are visualized in the replicated portions of UV-irradiated RI molecules; such regions are detected and clearly distinguishable from double-stranded DNA when probed by a specific single-stranded DNA-binding protein such as the bacteriophage T4 gene 32 product. Consistent with the presence of gaps in UV-irradiated RI molecules, single-strand-specific S1 nuclease digestion causes a shift in their sedimentation properties when analyzed in neutral sucrose gradients compared with undamaged molecules

  1. Acute effects of irradiation on exocrine pancreatic secretion in the pig

    Monti, P.; Scanff, P.; Joubert, C.; Vergnet, M.; Grison, S. [CEA Fontenay-aux-Roses, 92 (France). Inst. de Protection et de Surete Nucleaire

    1997-03-01

    Several reports on irradiation damages to the pancreas deal essentially with long-term morphologic changes but give few informations on pancreatic exocrine function. Therefore, the aim of the present work was to study the effects of a whole body gamma irradiation on the volume and enzyme activities of the pancreatic juice. The volume of pancreatic juice daily secreted decreased one day after irradiation (-40%, p < 0.01) and remained lower that the control value all over the experimental period (-65%, p < 0.01). Same response was observed for the total proteins secreted in the pancreatic juice but significant decrease was observed only the fourth and the fifth days after irradiation. Therefore, concentration of total protein secreted in the pancreatic juice was not altered all over the experimental period. Total activities of proteolytic enzymes, lipase and amylase led to decrease on day after irradiation and except for trypsin, the attenuated activity became significant from the third day after exposure. On the other hand, specific activities of the proteolytic enzymes and amylase did not show marked modifications after irradiation, whereas lipase specific activity was decreased. In conclusion, a whole body gamma irradiation resulted in a rapid and marked decrease of exocrine pancreatic secretion, in terms of volume as well as secreted enzymes. These modifications may, in part, contribute to the malabsorption of nutrients and these acute effects may be due to some modifications in the regulation of the exocrine pancreatic secretion

  2. Acute effects of irradiation on exocrine pancreatic secretion in the pig

    Several reports on irradiation damages to the pancreas deal essentially with long-term morphologic changes but give few informations on pancreatic exocrine function. Therefore, the aim of the present work was to study the effects of a whole body gamma irradiation on the volume and enzyme activities of the pancreatic juice. The volume of pancreatic juice daily secreted decreased one day after irradiation (-40%, p < 0.01) and remained lower that the control value all over the experimental period (-65%, p < 0.01). Same response was observed for the total proteins secreted in the pancreatic juice but significant decrease was observed only the fourth and the fifth days after irradiation. Therefore, concentration of total protein secreted in the pancreatic juice was not altered all over the experimental period. Total activities of proteolytic enzymes, lipase and amylase led to decrease on day after irradiation and except for trypsin, the attenuated activity became significant from the third day after exposure. On the other hand, specific activities of the proteolytic enzymes and amylase did not show marked modifications after irradiation, whereas lipase specific activity was decreased. In conclusion, a whole body gamma irradiation resulted in a rapid and marked decrease of exocrine pancreatic secretion, in terms of volume as well as secreted enzymes. These modifications may, in part, contribute to the malabsorption of nutrients and these acute effects may be due to some modifications in the regulation of the exocrine pancreatic secretion

  3. Nicotinamide adenosine dinucleotide level in dimethylsulfate-treated or UV-irradiated mouse epidermis

    The level of nicotinamide (NAD) has been determined in the epidermis of 30 mice. Its value is 0.63+-0.15 μg/mg protein. Upon treatment with dimethylsulfate (DMS), the level of NAD drops in a dosedependent fashion. This diminution is reversible when low doses of DMS are used. Upon irradiation with ultraviolet light, the level of NAD drops in the irradiated epidermis, the treshold of saturation being below 1200 J/m2. There is also a drop in the level of NAD in the epidermis protected against irradiation with a black rubber sheet. (author). 17 refs.; 6 figs.; 1 tab

  4. Heat shock mRNA in mouse epidermis after UV irradiation

    Total RNA form murine epidermis was extracted at different times after irradiation with erythemogenic doses of ultraviolet light and hybridized to a DNA probe from the gene of a heat shock protein (hsp 70). An intense and transitory enrichment in RNA molecules hybridizeing to the DNA probe was found between 15 and 120 min after irradiation, followed by a return co control levels over the next 70 h. Dose-response analysis indicates that 30 min after the irradiation, the relative amount of RNA hybridizing to the hsp 70 DNA probe increases with the dose up to values greater than 5 times the control. (Author). 14 refs.; 5 figs

  5. Protective effect of gelatin and gelatin hydrolysate from salmon skin on UV irradiation-induced photoaging of mice skin

    Chen, Tiejun; Hou, Hu; Lu, Jiaohan; Zhang, Kai; Li, Bafang

    2016-08-01

    The objective of this study was to investigate the effect of gelatin (SG) isolated from salmon skin and its hydrolysate (SGH) on photoaging skin, and the mechanism responsible for anti-photoaging. The average molecular weights of SG and SGH were 65 kDa and 873 Da, respectively. The amino acid compositions of SG and SGH were similar. Both of them were abundant in hydrophobic amino acids. Twenty-five peptides were identified from SGH. SG and SGH could improve UV irradiation-induced pathological changes of macroscopical tissue texture and skin morphology. Hydroxyproline content is an indicator of matrix collagen content, SG and SGH could inhibit the decrease of hydroxyproline content in photoaging skin in a dose dependent manner. In addition, SG and SGH could alleviate UV irradiation-induced oxidative damages to skin by increasing the activities of total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px) and catalase (CAT), increasing the content of glutathione (GSH) and decreasing the content of malonaldehyde (MDA). Moreover, SG and SGH could enhance immune regulation system by increasing the thymus index. Thus, the anti-photoaging mechanisms of SG and SGH were by inhibiting the depletion of antioxidant defense components, involving in the synthesis of collagen and enhancing the function of immune system. Besides, SGH showed a better result in protecting skin from photoaging than SG.

  6. Antioxidant activity for spice oils (1) anti oxidative stability of thyme and caraway oil extracts under UV-irradiation

    The anti oxidative activity for some spice essential oils have been investigated using thiocyanate method and compared with common natural antioxidant. The antioxidant activity for nine spice oils has been measured at 500 ppm after 13 days. The most potent one was the lemon grass (99.8), followed by orange peel, thyme, and caraway. The activities for these four oils were higher than that for Alpha-tocopherol (87.7%). Petitgrain, and geranium oils have marched activity but less than that for Alpha-tocopherol. No obvious has been found for citronella. fennel, and cardamon oils. The aqueous, butanoic, methanolic and hexanoic extracts for thyme and caraway oil exhibit effective anti oxidative activities under UV irradiation (254 nm) for 6 and 10 hr compared with that for alpha-tocopherol. The anti oxidative effect of thyme and caraway oil extracts were found to be strong and stable towards UV-irradiation, and equal to that for Alpha-tocopherol. Thyme's aqueous and caraway's hexanal extracts were the most potent extracts under the same conditions

  7. Air plasma or UV-irradiation applied to surface modification of pectin/poly(vinyl alcohol) blends

    Poly(vinyl alcohol), pectin and their blends with different components ratio were exposed to low-temperature air plasma or high energy UV-irradiation (λ = 254 nm) for the purpose of surface modification. The physico-chemical changes in surface properties have been studied by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and contact angle measurements. Surface free energy of polymeric films, its polar and dispersive components have been calculated by Owens-Wendt method. Moreover, the work of adhesion was estimated and the recovery of hydrophobic properties of modified films after storage have been also studied. The few seconds air-plasma treatment caused more effective surface modification than 5-6 h UV-irradiation. The observed changes were partially reversible, contrary to these caused by photo-modification. It was found that pectin/PVA (50:50) blend was characterised by larger susceptibility to plasma modification compared to pure pectin and pure PVA, whereas the photosensitivity to radiation of 254 nm wavelength was the lowest for this specimen in comparison to other studied samples.

  8. Air plasma or UV-irradiation applied to surface modification of pectin/poly(vinyl alcohol) blends

    Kowalonek, Jolanta; Kaczmarek, Halina; Dąbrowska, Aldona

    2010-10-01

    Poly(vinyl alcohol), pectin and their blends with different components ratio were exposed to low-temperature air plasma or high energy UV-irradiation ( λ = 254 nm) for the purpose of surface modification. The physico-chemical changes in surface properties have been studied by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and contact angle measurements. Surface free energy of polymeric films, its polar and dispersive components have been calculated by Owens-Wendt method. Moreover, the work of adhesion was estimated and the recovery of hydrophobic properties of modified films after storage have been also studied. The few seconds air-plasma treatment caused more effective surface modification than 5-6 h UV-irradiation. The observed changes were partially reversible, contrary to these caused by photo-modification. It was found that pectin/PVA (50:50) blend was characterised by larger susceptibility to plasma modification compared to pure pectin and pure PVA, whereas the photosensitivity to radiation of 254 nm wavelength was the lowest for this specimen in comparison to other studied samples.

  9. Air plasma or UV-irradiation applied to surface modification of pectin/poly(vinyl alcohol) blends

    Kowalonek, Jolanta [Faculty of Chemistry, Nicolaus Copernicus University, Gagarin 7 street, 87-100 Torun (Poland); Kaczmarek, Halina, E-mail: halina@chem.uni.torun.pl [Faculty of Chemistry, Nicolaus Copernicus University, Gagarin 7 street, 87-100 Torun (Poland); Dabrowska, Aldona [Faculty of Chemistry, Nicolaus Copernicus University, Gagarin 7 street, 87-100 Torun (Poland)

    2010-10-15

    Poly(vinyl alcohol), pectin and their blends with different components ratio were exposed to low-temperature air plasma or high energy UV-irradiation ({lambda} = 254 nm) for the purpose of surface modification. The physico-chemical changes in surface properties have been studied by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and contact angle measurements. Surface free energy of polymeric films, its polar and dispersive components have been calculated by Owens-Wendt method. Moreover, the work of adhesion was estimated and the recovery of hydrophobic properties of modified films after storage have been also studied. The few seconds air-plasma treatment caused more effective surface modification than 5-6 h UV-irradiation. The observed changes were partially reversible, contrary to these caused by photo-modification. It was found that pectin/PVA (50:50) blend was characterised by larger susceptibility to plasma modification compared to pure pectin and pure PVA, whereas the photosensitivity to radiation of 254 nm wavelength was the lowest for this specimen in comparison to other studied samples.

  10. Photodegradation of perfluorooctanoic acid by synthesized TiO2-MWCNT composites under 365nm UV irradiation.

    Song, Chao; Chen, Peng; Wang, Chunying; Zhu, Lingyan

    2012-02-01

    Degradation of perfluorooctanoic acid (PFOA) is of great importance due to its global distribution, persistence and toxicity to bioorganisms. In present study, a composite TiO(2) with multiple wall carbon nanotubes (MWCNTs) was synthesized using sol-gel method and it was used as photocatalyst to degrade PFOA in water. The prepared composite catalyst displayed significant absorption in UV to visible light region. The loading content of TiO(2) on MWCNTs could be adjusted by changing the ratio of precursor to MWCNTs. Due to the combined effect of the adsorption ability and e(-) transport capacity of MWCNT, the composites displayed much higher photocatalytic ability to PFOA as compared to pure TiO(2) under UV irradiation. The photocatalyst prepared with 10:1 of tetrabutyl titanate/MWCNT was the most effective. With the optimal dosage at 1.6 g L(-1), almost 100% of PFOA was degraded in acid medium after irradiation for 8h. It was proposed that PFOA were mainly degraded by stepwise losing a moiety of CF(2). PMID:22172634

  11. Protective effect of gelatin and gelatin hydrolysate from salmon skin on UV irradiation-induced photoaging of mice skin

    Chen, Tiejun; Hou, Hu; Lu, Jiaohan; Zhang, Kai; Li, Bafang

    2016-05-01

    The objective of this study was to investigate the effect of gelatin (SG) isolated from salmon skin and its hydrolysate (SGH) on photoaging skin, and the mechanism responsible for anti-photoaging. The average molecular weights of SG and SGH were 65 kDa and 873 Da, respectively. The amino acid compositions of SG and SGH were similar. Both of them were abundant in hydrophobic amino acids. Twenty-five peptides were identified from SGH. SG and SGH could improve UV irradiation-induced pathological changes of macroscopical tissue texture and skin morphology. Hydroxyproline content is an indicator of matrix collagen content, SG and SGH could inhibit the decrease of hydroxyproline content in photoaging skin in a dose dependent manner. In addition, SG and SGH could alleviate UV irradiation-induced oxidative damages to skin by increasing the activities of total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px) and catalase (CAT), increasing the content of glutathione (GSH) and decreasing the content of malonaldehyde (MDA). Moreover, SG and SGH could enhance immune regulation system by increasing the thymus index. Thus, the anti-photoaging mechanisms of SG and SGH were by inhibiting the depletion of antioxidant defense components, involving in the synthesis of collagen and enhancing the function of immune system. Besides, SGH showed a better result in protecting skin from photoaging than SG.

  12. Removal of binary azo dyes from water by UV-irradiated degradation in TiO2 suspensions

    Photodegradation and mineralization of single and binary Acid Orange 7 (AO7) and Reactive Red 2 (RR2) under UV irradiation in TiO2 suspensions was examined. Experiments were conducted as a function of initial pH, TiO2 dose, and initial dye concentration. First-order derivative spectrophotometric method was used to simultaneously analyze AO7 and RR2 in binary solutions. The Langmuir-Hinshelwood kinetic model was applied to evaluate and compare the apparent rate constants for the photodegradation of both dyes in single and binary solutions. It was shown that photodegradation of both dyes in binary solution was slower than those in single solution under comparable conditions. Moreover, the difference between the apparent rate constants of RR2 and AO7 became smaller in contrast to the cases of single solutions. After 20-min UV irradiation with 0.5 g/L TiO2, complete removal of single 0.086 mM AO7 and 0.086 mM RR2 at pH 6.8 was obtained, but only 60% and 45% of binary 0.086 mM AO7 and 0.086 mM RR2 was removed, respectively.

  13. An Acute Transverse Myelitis Attack after Total Body Irradiation: A Rare Case

    Muzaffer Keklik

    2013-01-01

    Full Text Available Total body irradiation (TBI combined with chemotherapy is widely used as a pretreatment regimen of bone marrow transplantation (BMT in hematologic disorders. Late complications related to TBI as part of the conditioning regimen for hematopoietic stem cell transplantation have been revealed. Acute transverse myelitis (ATM is a neurological syndrome characterized by disorder of motor, sensorial, and autonomic nerves, and tracts at medulla spinalis, which is resulted from involvement of spinal cord. In this paper, we presented an ATM attack developed after TBI in a patient with acute lymphoblastic leukemia (ALL as it is a rarely seen case.

  14. The UV-irradiated mouse as a model for testing biological response modifiers

    In addition to inducing primary cancers of the skin, ultraviolet (UV) radiation produces specific impairments in the immune system that contribute to the growth and pathogenesis of these skin cancers. The cellular basis for the immunological alterations induced in mice by UV radiation has been studied and characterized over the past ten years. It is now possible to make use of this system to study the activity and mode of action of biological response modifiers. The advantages of this system are that it employs primary hosts, which may respond quite differently from normal animals bearing a transplanted tumor, it closely parallels several specific situations relevant to human cancer, and it may be useful in establishing the mechanism of action of certain agents. Studies in which biological response modifiers have been used in conjunction with the UV carcinogenesis model are reviewed. (Auth.)

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

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

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

    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)

  17. Solar UV irradiance measured at ground and compared with satellite TOMS/NASA derived data at different locations in Argentina

    Wolfram, W.; Quel, E.; Paladini, A.; Orce, V.; Piacentini, R. D.

    The solar UV radiation incident on different and distant places of Argentina (Ushuaia, Puerto Madryn, Buenos Aires and Jujuy) obtained at 305, 320, 340 and 380 nm with a GUV-511/Biospherical narrowband radiometer of the CONICET Latitudinal UV-PAR radiation monitoring network, were compared with TUV model calculations in order to derive the effective aerosol optical depths in the locations indicated above. The adjusted spectral curve is employed in order to determine, -with the inclusion of the erythemal action spectrum, the corresponding integrated dose for each day. This value, usually called exposure, is compared with the data derived at noon from those taken by the satellite instrument TOMS/NASA on board of Earth Probe. Other biological UV irradiances like carcinogenesis and ADN and plant damages are also analyzed. In particular, the signals produced by the ozone hole and minihole events (with values lowers or equal to 220 DU) are clearly distinguished in the biological actions that depend strongly on the most energetic UVB radiations.

  18. UV-B sensitivity of plant photosynthesis as influenced by visible irradiation

    Experiments were made to separate the effects of preconditioning and concomitant visible irradiation and to investigate this with respect to both light-limited and light-saturated photosynthesis. (orig./AJ)

  19. Repair of single-strand breaks induced in the DNA of Proteus mirabilis by excision repair after UV-irradiation

    Single-strand breaks have been produced in the DNA of P. mirabilis after UV-irradiation in dependence on the incident UV-doses. It has been found that there exists a discrepancy between the single-strand breaks estimated from sedimentation in alkaline sucrose gradients and the expected single-strand breaks approximated from measurements of dimer excision. The low number in incision breaks observed by sedimentation experiments is an indication that the cells are able to repair the excision-induced breaks as fast as they are formed. Toluenized cells have been used for investigation of the incision step independently of subsequent repair processes. In presence of NMN the appearance of more single-strand breaks in the DNA has been observed. Furthermore, the number of incision breaks in toluenized cells increased in presence of exogenous ATP. The completion of the excision repair process has been investigated by observing the rejoining of incision breaks. After irradiation with UV-doses higher than approximately 240 erg/mm2 the number of single-strand breaks remaining unrepaired in the DNA increased. Studies of the influence of nutrition conditions on the repair process have shown approximately the same capacity for repair of single-strand breaks in growth medium as well as in buffer. Progress in the excision repair was also followed by investigation of the DNA synthesized at the template-DNA containing the pyrimidine dimers. In comparison with E. coli, P. mirabilis showed a somewhat lower efficiency for the repair of single-strand breaks during the excision repair. (author)

  20. Skin changes in 'screen dermatitis' versus classical UV- and ionizing irradiation-related damage - similarities and differences

    An increasing number of persons say that they get cutaneous problems as well as symptoms from certain internal organs, such as the central nervous system (CNS) and the heart, when being close to electric equipment. A major group of these patients are the users of video display terminals (VDTs), who claim to have subjective and objective skin- and mucosa-related symptoms, such as pain, itch, heat sensation, ery-therma, papules, and pustules. The CNS symptoms are, e.g. dizziness, tiredness, and headache. Erythema, itch, heat sensation, edema and pain are also common symptoms of sunburn (UV dermatitis). Alterations have been observed in cell populations of the skin of patients suffering from so-called 'screen dermatitis' similar to those observed in the skin damaged due to ultraviolet (UV) light or ionizing radiation. In 'screen dermatitis' patients a much higher number of mast cells have been observed. It is known that UVE irradiation induces mast cell degranulation and release of TNF-α. The high number of mast cells present in the 'screen dermatitis' patients and the possible release of specific substances, such as histamine, may explain their clinical symptoms of itch, pain, edema and erythema. The most remarkable change among cutaneous cells, after exposure with the above-mentioned irradiation sources, is the disappearance of the Langerhans' cells. This change has also been observed in 'screen dermatitis' patients, again pointing to a common cellular and molecular basis. The results of this literature study demonstrate that highly similar changes exist in the skin of 'screen dermatitis' patients, as regard the clinical manifestations as well as alterations in the cell populations, and in skin damaged by UV light or ionizing radiation. (au)

  1. EPR study of UV irradiation effect on impurity sites in calcium orthovanadate

    Impurity paramagnetic sites (PS) of Fe(3) and v(4), localized in calcium and vanadium sublattices, are revealed in diamagnetic calcium orthovanadate. It is shown that induced PS don't form in orthovanadate under rigid ultraviolet irradiation. It was revealed that ultraviolet irradiation resulted to deformation of calcium-oxygen polyhedrons. It preserved in the case of sample heating, but disappeared after transmission of molecular gases at 260 deg C above the surface of orthovanadate. 9 refs., 3 figs., 1 tab

  2. Modifying effect of caffeine on lethality and mutability of Chlamydomonas reinhardii cells following UV irradiation

    The modifying effect of caffeine was studied using two standard and two UV-sensitive strains of Chlamydomonas reinhardii Dang. Cell survival and mutation frequency was microscopically evaluated on media without caffeine and on media with 1.5 mM of caffeine. The obtained results were indicative of the stimulating effect of caffeine upon survival in all strains. (author)

  3. Design and fabrication of an optical dosimeter for UV and gamma irradiation

    Ramirez-Nino, J; Castano, V M

    1999-01-01

    A simple UV and gamma radiation optical dosimeter is presented. The organic dye degradation with radiation absorption is used to measure the radiation dose. The design, the electronic circuit, the calibration and the operation procedure are also described in detail. Finally, the results of actual applications are shown with beta-carotene in an acetone/ethanol solution utilised as an optical probe.

  4. Antioxidant Capacities and Total Phenolic Contents Enhancement with Acute Gamma Irradiation in Curcuma alismatifolia (Zingiberaceae) Leaves

    Sima Taheri; Thohirah Lee Abdullah; Ehsan Karimi; Ehsan Oskoueian; Mahdi Ebrahimi

    2014-01-01

    The present study was conducted in order to assess the effect of various doses of acute gamma irradiation (0, 10, 15, and 20 Gy) on the improvement of bioactive compounds and their antioxidant properties of Curcuma alismatifolia var. Sweet pink. The high performance liquid chromatography (HPLC) and gas chromatography (GC) analysis uncovered that various types of phenolic, flavonoid compounds, and fatty acids gradually altered in response to radiation doses. On the other hand, antioxidant act...

  5. Glioblastoma multiforme following prophylactic cranial irradiation and intrathecal methotrexate in a child with acute lymphocytic leukemia

    Cases of radiation-induced glioma in humans are extremely rare. A 2-year-old boy with acute lymphocytic leukemia had received prophylactic cranial irradiation (2400 rad/2 1/2 weeks) and intrathecal methotrexate. Five years later he developed a glioblastoma multiforme on the left cerebral hemisphere while the leukemia was in remission. This is the first reported association of these disorders. It is possible that the glioma may have been induced by radiation and/or chemotherapy

  6. An Acute Transverse Myelitis Attack after Total Body Irradiation: A Rare Case

    Ali Unal; Bulent Eser; Mustafa Cetin; Cigdem Pala; Serife Cingoz; Celalettin Eroglu; Serdar Sivgin; Leylagul Kaynar; Afra Yildirim; Muzaffer Keklik

    2013-01-01

    Total body irradiation (TBI) combined with chemotherapy is widely used as a pretreatment regimen of bone marrow transplantation (BMT) in hematologic disorders. Late complications related to TBI as part of the conditioning regimen for hematopoietic stem cell transplantation have been revealed. Acute transverse myelitis (ATM) is a neurological syndrome characterized by disorder of motor, sensorial, and autonomic nerves, and tracts at medulla spinalis, which is resulted from involvement of spina...

  7. A new method of chlorophenols decomposition based on UV-irradiation by XeBr-excilamp and their subsequent biodegradation

    Sosnin, E. A.; Matafonova, G. G.; Batoev, V. B.; Christofi, N.

    2008-01-01

    The combined decomposition method of chlorophenols (CP) is offered. The method is based on photolysis of CP through XeBr-excilamp UV irradiation at 283 nm in a flow photoreactor with subsequent treatment of photolysis products by microorganism-destructor B. cereus isolated from an aeration pond of Baikal pulp-and-paper mill. At initial concentration of CP of 20 mg/l the polluted solutions can be utilized directly by means of biological treatment using B. cereus under aerobic conditions. However, if the initial CP concentration is higher than 20 mg/l, the polluted solutions are low biodegradable. It is shown, that the combined treatment is most effective method in this case. At initial CP concentration of 50 mg/l and higher it is suggested to use the deep preliminary UV-treatment with the purpose of removal 80-90 % of initial CP. It is revealed, that 4-CP is relatively persistent compound for B. cereus, easily decomposed by UV-radiation of XeBr-excilamp. As a result of subsequent biological treatment during 10 days the utilization of basic CP photoproducts is obtained. Experimentally, the preliminary UV-processing time was essentially less than that found earlier by E. Tamer, Z. Hamid, Aly A. (Chemosphere, 2006), where the half-life periods of initial CP were from 2.2 to 54 hours at the same value of initial concentration of CP. Correspondingly, the total CP decomposition process was accompanied by high power inputs. It is suggested to use mentioned above method for effective CP decomposition at high concentration values.

  8. Continuous, pulsed or single acute irradiation of a transplanted rodent tumour model

    Background: Recent advances in remote afterloading pulsed mode brachytherapy have provided a much needed tool for the radiation oncologist. It has the versatility of optimised physical dose distribution along with improved staff radiation protection and patient nursing. Purpose: This preliminary study was designed to explore the radiobiological equivalence between conventional continuous low dose rate tumour irradiation (CLDR) and the new technique of pulsed dose irradiation (PDR). Materials and methods: Subcutaneous isogenic sarcomas transplanted in female John's Strain Wistar rats were irradiated locally with acute, pulsed or continuous interstitial low dose-rate exposures at 9-11 mm mean diameter. Results: As expected, single acute doses (5-40 Gy) were more effective (P < 0.01) in achieving tumour growth delay (1.4 days/Gy) than CLDR exposure (4-51 Gy) over 24-48 h (0.93 days/Gy). However, PDR treatment (8 hourly fractions/day) at high dose-rate (8-48Gy) over 8-72 h was significantly (P = 0.01) more effective (1.66 days/Gy) than CLDR but not acute exposures. Conclusions: These data suggest that, clinically a significantly improved therapeutic ratio may also be achievable with pulsed high dose rate brachytherapy, and that further radiobiological studies with in-vivo tumour models are needed

  9. Naphthalene degradation in seawater by UV irradiation: The effects of fluence rate, salinity, temperature and initial concentration

    Highlights: • The removal of naphthalene follows first order kinetics in seawater. • Irradiance and temperature are the most influential factors. • An increase in irradiance can linearly promote photodegradation. • High salinity suppresses the photodegradation of naphthalene. - Abstract: A large amount of oil pollution at sea is produced by the operational discharge of oily wastewater. The removal of polycyclic aromatic hydrocarbons (PAHs) from such sources using UV irradiation has become attractive, yet the photolysis mechanism in seawater has remained unclear. This study examines the photodegradation kinetics of naphthalene in natural seawater through a full factorial design of experiments (DOE). The effects of fluence rate, salinity, temperature and initial concentration are investigated. Results show that fluence rate, temperature and the interaction between temperature and initial concentration are the most influential factors. An increase in fluence rate can linearly promote the photodegradation process. Salinity increasingly impedes the removal of naphthalene because of the existence of free-radical scavengers and photon competitors. The results will help understand the photolysis mechanism of PAHs and develop more effective methods for treating oily seawater generated from offshore industries

  10. Growth in children treated for acute lymphoblastic leukemia with and without prophylactic cranial irradiation

    Moell, C.; Garwicz, S.; Marky, L.; Melander, L.; Karlberg, J.

    1988-01-01

    Growth and weight gain were studied longitudinally over a period of four years in thirty-nine children treated for acute lymphoblastic leukemia. The children were divided into two groups according to treatment. Twenty-eight children were given prophylactic cranial irradiation and eleven children were treated without such irradiation. The duration of cytostatic treatment was three years in all cases. Average growth during the first two years was similar in the two groups, and the standard deviation scores (SDS) were below average. The rate of growth during the fourth year was significantly higher among those children who had not received cranial irradiation. After four years the average attained height had declined 0.5 SD for children treated with cranial irradiation and 0.2 SD for children without such treatment. Attained weight after four years had increased 0.4 SD more among those children who had not received irradiation. The results suggest that prophylactic cranial irradiation is responsible for the greater part of the prepubertal growth inhibition in these children. (authors).

  11. Growth in children treated for acute lymphoblastic leukemia with and without prophylactic cranial irradiation

    Growth and weight gain were studied longitudinally over a period of four years in thirty-nine children treated for acute lymphoblastic leukemia. The children were divided into two groups according to treatment. Twenty-eight children were given prophylactic cranial irradiation and eleven children were treated without such irradiation. The duration of cytostatic treatment was three years in all cases. Average growth during the first two years was similar in the two groups, and the standard deviation scores (SDS) were below average. The rate of growth during the fourth year was significantly higher among those children who had not received cranial irradiation. After four years the average attained height had declined 0.5 SD for children treated with cranial irradiation and 0.2 SD for children without such treatment. Attained weight after four years had increased 0.4 SD more among those children who had not received irradiation. The results suggest that prophylactic cranial irradiation is responsible for the greater part of the prepubertal growth inhibition in these children. (authors)

  12. Migration patterns of dendritic cells in the rat: comparison of the effects of gamma and UV-B irradiation on the migration of dendritic cells and lymphocytes

    To further define the underlying mechanisms of immune suppression induced by UV-B irradiation, we have examined the kinetics of homing patterns of in vitro UV-B-irradiated and gamma-irradiated-thoracic duct lymphocytes (TDL) compared to dendritic cells (DC). Our findings show that 111In-oxine-labeled TDL specifically home to the spleen, liver, lymph nodes, and bone marrow with subsequent recirculation of a large number of cells from the spleen to lymph nodes. In contrast, DC preferentially migrate to the spleen and liver with a relatively insignificant distribution to lymph nodes and an absence of subsequent recirculation. Splenectomy prior to cell injection significantly diverts the spleen-seeking DC to the liver but not to the lymph nodes, while the homing of TDL to lymph nodes is significantly increased. In vitro exposure of 111In-oxine labeled TDL to gamma irradiation does not significantly impair immediate homing to lymphoid tissues but inhibits cell recirculation between 3 and 24 hr. In contrast, gamma irradiation does not affect the tissue distribution of labeled DC, suggesting that DC are more radioresistant to gamma irradiation than TDL. Unlike the findings in animals injected with gamma-irradiated cells, UV-B irradiation virtually abolished the homing of TDL to lymph nodes and significantly reduced the homing of the spleen-seeking DC to the splenic compartment while a large number of cells were sequestered in the liver. The results of in vitro cell binding assay show that TDL, unlike DC, have the capacity to bind to high endothelial venules (HEV) within lymph node frozen sections while gamma and UV-B irradiation significantly inhibit the binding of TDL to lymph node HEV

  13. Acute and long-term effects of irradiation on pine (Pinus silvestris) stands post-Chernobyl

    Arkhipov, N.P.; Kuchma, N.D. (Department of Radiology and Land Restoration, Pripyat Research and Industrial Association, Chernobyl (Ukraine)); Askbrant, S. (National Radiation Protection Institute, Stockholm (Sweden)); Pasternak, P.S.; Musica, V.V. (Lyes Research and Industrial Association, Kharykov (Ukraine))

    1994-10-14

    The effect of ionizing irradiation on the viability of pine stands after the fallout from the damaged nuclear energy plant at Chernobyl (ChNPP) was shown within the territory of the 10-km zone. During the period 1986-1991, irradiated and damaged forest stands, so-called 'red forest', located in this area were systematically classified by observation. Mortality rate, re-establishment, development of tree canopies, reproduction anomalies and stand viability were shown to be dependent on absorbed irradiation dose, on the age of the stand and on forest composition. For pine stands in the acutely affected zone, doses of more than 60 Gy resulted in a massive mortality and no regeneration of pine trees since 1987. The injured trees had burned or had dried-up. The drying process was accelerated by a massive production of pathogenic insects invading the dying trees. Specifically, irradiation doses of 10-60 Gy, 1-10 Gy and 0.1-1 Gy caused high, medium and low injury to the forest stands, respectively. Doses of less than 0.1 Gy did not cause any visible damage to the trees. In 1987, repair processes were displayed by the tree canopies and practically the entire viability of the forest stands had recovered except for trees in the acute and highly affected zones. The young forest was reestablished in the same place as the perished trees and new pine saplings were planted on the reclaimed areas.

  14. Studies on acute toxicity and mutagenicity of 60Co irradiated pollens

    The acute toxicity test showed that the oral LD50 values were >21500 mg/kg for male and female mice, indicating that irradiated pollens belong to low toxicity grade or practically non-toxic. Mutagenicity were studied in three short-term tests. Ames test showed that irradiated pollens did not induce mutation towards strains TA99, TA97, TA100 and TA102. Micronucleus test in the bone marrow cells indicated that the percentage of polychromatic erythrocytes with micronuclei in exposed groups had no significant difference in comparison with the controlled ones. Chromosomal test for reproduction cells showed that the increase of chromosomal aberration rate was not observed. All the above results suggest that irradiated pollens are safe for human consumption

  15. A new parameterization of the UV irradiance altitude dependence for clear-sky conditions and its application in the on-line UV tool over Northern Eurasia

    N. Chubarova; Zhdanova, Y.; Nezval, Y.

    2016-01-01

    A new method for calculating the altitude UV dependence is proposed for different types of biologically active UV radiation (erythemally-weighted, vitamin-D-weighted and cataract-weighted types). We show that for the specified groups of parameters the altitude UV amplification (AUV) can be presented as a composite of independent contributions of UV amplification from different factors within a wide range of their changes with mean uncertainty of 1 % and standard deviation of 3 % c...

  16. Excision repair in MUT-mutants of Proteus mirabilis after UV-irradiation

    The behaviour of MUT-mutants of P.mirabilis to perform certain steps of excision repair after U.V.-irradiation is described. MUT-mutants introduce single-strand breaks in the DNA immediately after U.V.-irradiation, but their ability to excise pyrimidine dimers from the DNA is very diminished. Moreover, they are not able to accomplish the excision repair by rejoining of the single-strand breaks. The connection between the incomplete excision repair and the mutator phenotype of these mutants is discussed. (author)

  17. Uv - b irradiation effects on biological activities and cytological behavior of sainfoin (onobrychis viciifolia scop.) grown in vivo and in vitro

    To investigate the feasibility of UV-B irradiation (312 nm), seeds of Onobrychis viciifolia were exposed to five different intensities for determining the effectiveness of cellular behavior, nutritional constituents and biological activities in In vivo and In vitro growth cultures. The atomic spectroscopy analysis confirmed that concentrations of two macronutrients (P and N) improved after UV-B exposure as compared with control plants. Near infrared radiation conducted on both In vivo and In vitro plants showed significant differences on dry matter digestibility (DMD) and crude fiber (CF). Flavonoid and phenolic compounds were increased in both growth cultures by 40 percentage intensity of UV-B irradiation, although In vitro plants had the higher compounds than intact plants. Increasing the UV-B irradiation intensity was also found to yield positive effect on anthocyanin. Observations on cellular behavior such as determination of nuclear and cell areas, mitotic index and chromosomal aberrations were proven to be essential in deducing the effectiveness of UV-B irradiation to induce somaclonal variation in sainfoin. (author)

  18. The effect of caffeine on p53-dependent radioresponses in undifferentiated mouse embryonal carcinoma cells after X-ray and UV-irradiations

    The effect of caffeine was studied on the radioresponses of undifferentiated mouse embryonal carcinoma cells (EC cells) with or without the functional p53. The radioresponses studied included radiosensitivity, the activation of p53, apoptosis with characteristic DNA ladder formation and cell cycle progression. An undifferentiated mouse EC cell line, ECA2, and a newly established p53-deficient EC cell line, p53δ, were used in the present study. The status of the p53 gene did not significantly affect the colony survivals of undifferentiated EC cells to X-rays and UV. Although a post-irradiation treatment with caffeine sensitized both lines to X-rays marginally, the sensitization was prominent for UV regardless of the p53 status of the cells. The activation of a p53 responsible lacZ reporter construct was observed in stably transfected ECA2 cells after X-ray and UV irradiations. Caffeine suppressed the X-ray induced activation of the lacZ reporter, while it drastically enhanced the activation after UV irradiation. X-rays and UV readily triggered the apoptosis of ECA2 cells with the characteristic DNA ladder. Although UV-induced DNA ladder formation was enhanced by caffeine, that induced by X-rays was unaffected. Therefore, the effects of caffeine on the p53-dependent radioresponses were found to be agent specific: suppression for the X-ray induced and augmentation for the UV induced. In contrast to p53-proficient ECA2 cells, smear-like DNA degradation was observed for irradiated p53δ cells, suggesting the presence of a mode of cell death without DNA ladder formation. UV induction of the smear-like DNA degradation was enhanced in the presence of caffeine. Regardless of the state of the p53 gene, G1/S arrest was not observed in X-ray and UV irradiated EC cells. X-rays induced G2/M arrest in both lines, which was abrogated by caffeine, while G2/M arrest after UV was unaffected by a caffeine treatment. These results indicate that the radioresponses of undifferentiated

  19. Photolysis of organic pollutants in wastewater with 206 nm UV irradiation

    Zhao Lian Ye; Chang Qing Cao; Jin Cong He; Ren Xi Zhang; Hui Qi Hou

    2009-01-01

    A new-type UV light source (206 nm) was explored for the degradation of organic pollutants in wastewater for the first time. The degradation performances of triphenyltin chloride (TPTC1), dimethyl phthalate (DMP), as well as rhodamine B (RhB) were investigated. The results indicated that removal efficiency of 50 mg/L RhB, 60 mg/L DMP and 120 mg/LTPTC1 can reach 88.6%,92.5% and 89.4% for 60 min, 50 min and 75 min, respectively. By comparison of removal efficiency, we found 206 nm is superior to 253.7 nm UV in wastewater treatment, implying it is an effective, promising, and worthwhile exploring technology to decompose organic pollutants in wastewater.

  20. The inactivation of hepatitis A virus and other model viruses by UV irradiation

    Battigelli, D.A.; Sobsey, M.D.; Lobe, D.C. (North Carolina Univ., Chapel Hill, NC (United States). Dept. of Environmental Sciences)

    1993-01-01

    Ultraviolet light is an attractive alternative to chemical disinfection of water, but little is known about its ability to inactivate important waterborne pathogens such as hepatitis A virus. Therefore, the sensitivity of HAV strain HM-175, coxsackievirus type B-5, rotavirus strain SA-11, and bacteriophages MS2 and [phi]X174 to ultraviolet radiation of 254 nm wavelength in phosphate buffered water was determined. Purified stocks of the viruses were combined and exposed to collimated UV radiation in a stirred reactor for a total dose of up to 40 mW sec/cm[sup 2]. Virus survival kinetics were determined from samples removed at dose intervals. The results of these experiments indicate that UV radiation can effectively inactivate viruses of public health concern in drinking water. (author).

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

    Fornwalt L

    2014-01-01

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

  2. The initiation mechanism of translesion DNA synthesis in response to UV irradiation

    Ultraviolet (UV) light causes DNA damage and increases a person's risk for both melanoma and non-melanoma skin cancer. If the DNA damage is unrepaired, cells can often tolerate it by using specialized DNA polymerases during DNA replication to insert a base opposite a lesion and bypass the damage, in a process called translesion DNA synthesis (TLS). This review addresses recent advances in our understanding of TLS. (author)

  3. Combined effect of UV-irradiation and TiO2-nanoparticles on the predator–prey interaction of gammarids and mayfly nymphs

    Although nanoparticle production and application increases continuously, their implications in species interactions, especially in combination with other environmental stressors, are rarely assessed. Therefore, the present study investigated the influence of 2 mg/L titanium dioxide nanoparticles (nTiO2; 2) as an additional environmental factor (n = 16). At the same time, gammarid's consumption of an alternative food source, i.e. leaf discs, was assessed. All endpoints covered were not affected by nTiO2 alone, while the combination of nTiO2 and UV caused a reduction in gammarid's predation (68%), leaf consumption (60%) and body weight (22%). These effects were most likely triggered by the UV-induced formation of reactive oxygen species by nTiO2. The present study, hence, highlights the importance to cover UV-irradiation during the risk assessment of nanoparticles. -- Highlights: • nTiO2 alone did not affect gammarids leaf consumption and predation on mayfly. • Ambient UV intensities affected significantly only gammarids leaf consumption. • Irradiation of nTiO2 by UV resulted in strong impact on both organisms. • Environmental factors alter nTiO2 toxicity. -- UV-irradiation influences nanoparticles' ecotoxicity rising concerns about adverse effects in trophic interactions and ecosystem functions

  4. The effect of caffeine on post-replication repair and survival in two L5178Y cell lines with different sensitivities to UV irradiation

    2 Strains of murine lymphoma L5178Y cells that varied from the point of view of sensitivity to UV irradiation (mean lethal doses: 3.6 and 8.5 J/m2 for L5178Y-R and L5178Y-S cells, respectively) also differed with respect to sensitization by caffeine. L5178Y-S cells were sensitized to UV irradiation by 0.75 mM caffeine, whereas in the same conditions L5178Y-R cells were not sensitized. Sedimentation analysis of the newly synthesized DNA indicated UV-induced gap formation in L5178Y-S cells only. The subsequent gap filling was inhibited by caffeine. Exposure to UV irradiation induced no gaps in L5178Y-R cells. However, when caffeine was added immediately after irradiation, DNA with reduced molecular weight was found in irradiated cells of both strains after a 2-h chase. On the other hand, caffeine inhibited elongation of undamaged DNA strands in neither of the 2 cell strains. (Auth.)

  5. Optical manipulation of Saccharomyces cerevisiae cells reveals that green light protection against UV irradiation is favored by low Ca2+ and requires intact UPR pathway.

    Farcasanu, Ileana C; Mitrica, Radu; Cristache, Ligia; Nicolau, Ioana; Ruta, Lavinia L; Paslaru, Liliana; Comorosan, Sorin

    2013-11-01

    Optical manipulation of Saccharomyces cerevisiae cells with high density green photons conferred protection against the deleterious effects of UV radiation. Combining chemical screening with UV irradiation of yeast cells, it was noted that the high density green photons relied on the presence of intact unfolded protein response (UPR) pathway to exert their protective effect and that the low Ca(2+) conditions boosted the effect. UPR chemical inducers tunicamycin, dithiotreitol and calcium chelators augmented the green light effect in a synergic action against UV-induced damage. Photo-manipulation of cells was a critical factor since the maximum protection was achieved only when cells were pre-exposed to green light. PMID:24056073

  6. Production and accumulation of UV-B [ultra violet] absorbing compounds in UV-B irradiated leaves of rice, Oryza SativaL.: effects of varying UV-B doses on leaf damage, phenolic content and HPLC [high performance liquid chromatography] peak I area

    The effects of varying UV-B doses on leaf damage, phenolic content and HPLC peak 1 area were studied using 65-d-old plants of the UV-B tolerant rice cultivar, M202, and the UV-B susceptible rice cultivar, Dular. Results showed that the production and accumulation of UV-B- absorbing compounds in rice leaves were affected by leaf position and levels (dose) of UV-B and time or duration of UV-B irradiation or exposure. The youngest terminal leaves showed the least damage when exposed to medium and high UV-B doses. The production of these absorptive compounds as represented by relative phenolic and HPLC peak 1 were significantly higher in younger leaves and lower in older or senescing leaves. M202 showed significantly higher amounts of peak 1 area and relative phenolic compared to UV-B susceptible rice cultivar, Dular. The results also confirmed the strong relationship of overall damage rating and area of HPLC peak 1. The development of UV-B symptoms in the susceptible cultivar was hastened when a high UV-B treatment was applied. Peak 1 area did not accumulate in the UV-B susceptible Dular at any given UV-B dose

  7. Superoxide radical and UV irradiation in ultrasound assisted oxidative desulfurization (UAOD): A potential alternative for greener fuels

    Chan, Ngo Yeung

    This study is aimed at improving the current ultrasound assisted oxidative desulfurization (UAOD) process by utilizing superoxide radical as oxidant. Research was also conducted to investigate the feasibility of ultraviolet (UV) irradiation-assisted desulfurization. These modifications can enhance the process with the following achievements: (1) Meet the upcoming sulfur standards on various fuels including diesel fuel oils and residual oils; (2) More efficient oxidant with significantly lower consumption in accordance with stoichiometry; (3) Energy saving by 90%; (4) Greater selectivity in petroleum composition. Currently, the UAOD process and subsequent modifications developed in University of Southern California by Professor Yen's research group have demonstrated high desulfurization efficiencies towards various fuels with the application of 30% wt. hydrogen peroxide as oxidant. The UAOD process has demonstrated more than 50% desulfurization of refractory organic sulfur compounds with the use of Venturella type catalysts. Application of quaternary ammonium fluoride as phase transfer catalyst has significantly improved the desulfurization efficiency to 95%. Recent modifications incorporating ionic liquids have shown that the modified UAOD process can produce ultra-low sulfur, or near-zero sulfur diesels under mild conditions with 70°C and atmospheric pressure. Nevertheless, the UAOD process is considered not to be particularly efficient with respect to oxidant and energy consumption. Batch studies have demonstrated that the UAOD process requires 100 fold more oxidant than the stoichiometic requirement to achieve high desulfurization yield. The expected high costs of purchasing, shipping and storage of the oxidant would reduce the practicability of the process. The excess use of oxidant is not economically desirable, and it also causes environmental and safety issues. Post treatments would be necessary to stabilize the unspent oxidant residual to prevent the waste

  8. Fe/Ti co-pillared clay for enhanced arsenite removal and photo oxidation under UV irradiation

    Li, Yuan; Cai, Xiaojiao; Guo, Jingwei; Zhou, Shimin; Na, Ping

    2015-01-01

    A series of iron and titanium co-pillared montmorillonites (Fe-Ti/MMT) were prepared using hydrolysis of inserted titanium and different iron content in montmorillonite (MMT). The Fe-Ti/MMT were characterized by X-ray fluorescence, N2 adsorption and desorption, X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM), confirming the effective insertion of Fe species and TiO2 in the MMT. The Fe-Ti/MMT was used to remove arsenite (As(III)) from aqueous solutions under different conditions. The result of As(III) adsorption under UV irradiation showed that the photo activity can be enhanced by incorporating Fe and Ti in MMT. Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis indicated that the hydroxyl groups bonded to metal oxide (M-OH) played an important role in the adsorption of As(III)

  9. High Refractive Organic–Inorganic Hybrid Films Prepared by Low Water Sol-Gel and UV-Irradiation Processes

    Hsiao-Yuan Ma

    2016-03-01

    Full Text Available Organic-inorganic hybrid sols (Ti–O–Si precursor were first synthesized by the sol-gel method at low addition of water, and were then employed to prepare a highly refractive hybrid optical film. This film was obtained by blending the Ti–O–Si precursor with 2-phenylphenoxyethyl acrylate (OPPEA to perform photo-polymerization by ultraviolet (UV irradiation. Results show that the film transparency of poly(Ti–O–Si precursor-co-OPPEA film is higher than that of a pure poly(Ti–O–Si precursor film, and that this poly(Ti–O–Si precursor-co-OPPEA hybrid film exhibits a high transparency of ~93.7% coupled with a high refractive index (n of 1.83 corresponding to a thickness of 2.59 μm.

  10. Naphthalene degradation in seawater by UV irradiation: the effects of fluence rate, salinity, temperature and initial concentration.

    Jing, Liang; Chen, Bing; Zhang, Baiyu; Zheng, Jisi; Liu, Bo

    2014-04-15

    A large amount of oil pollution at sea is produced by the operational discharge of oily wastewater. The removal of polycyclic aromatic hydrocarbons (PAHs) from such sources using UV irradiation has become attractive, yet the photolysis mechanism in seawater has remained unclear. This study examines the photodegradation kinetics of naphthalene in natural seawater through a full factorial design of experiments (DOE). The effects of fluence rate, salinity, temperature and initial concentration are investigated. Results show that fluence rate, temperature and the interaction between temperature and initial concentration are the most influential factors. An increase in fluence rate can linearly promote the photodegradation process. Salinity increasingly impedes the removal of naphthalene because of the existence of free-radical scavengers and photon competitors. The results will help understand the photolysis mechanism of PAHs and develop more effective methods for treating oily seawater generated from offshore industries. PMID:24576392

  11. The importance of the ratio UV-B/photosynthetic active radiation (PAR) during leaf development as determining factor of plant sensitivity to increased UV-B irradiance: effects on growth, gas exchange and pigmentation of bean plants (Phaseolus vulgaris cv. Label)

    To evaluate the effect of different naturally occurring irradiation conditions on the sensitivity of bean (Phaseolus vulgaris cv. Label) to increased UV-B levels, plants were grown under six different light treatments. In the control series (at ambient levels of UV-B), UV-B and visible light were decreased in parallel, resulting in three different total irradiation treatments with the same UV-B/PAR ratio. A second series with a 15% increase in UV-B irradiation at each PAR level was used to investigate the effect of UV-B under the varying total irradiance levels. The different total irradiance levels resulted in large differences in total dry weight, specific leaf weight, photosynthesis-light response and pigment concentrations. Nevertheless, the 15% increase in UV-B resulted in equal reductions in total dry weight (from 24.5 to 34.3%) and effective photosynthesis for all light levels. The accumulation of protective pigments in the primary bean leaves was strongly correlated to the total irradiance level (200% increase from the lowest to the highest light level), but was not influenced by increasing UV-B levels. As the UV-B/PAR ratio outside increases with decreasing total irradiance (when induced by cloud cover) this implies that low radiation levels are potentially dangerous to some plants, even though the UV-B levels may seem negligible. (author)

  12. Kidney and lung injury in irradiated rats protected from acute death by partial-body shielding

    Ninety-six CD-1 male rats were exposed to gamma-ray doses (0-25 Gy) in increments of 5 Gy. One femur, the surgically exteriorized GI tract, and the oral cavity were shielded during irradiation to protect against acute mortality from injury to the hematopoietic system, small intestine, and oral cavity. In addition, the thoraxes of half of the animals from each dose group were shielded. At approximately monthly intervals from 2 to 10 months after irradiation the hematocrit, plasma urea nitrogen (PUN), and 51Cr-EDTA clearance were measured. During the study 20 thorax-shielded and 19 thorax-irradiated animals died. All rats whose thoraxes received 25 Gy irradiation and three out of seven rats whose thoraxes received 20 Gy died 1 to 3 months postirradiation with massive pleural fluid accumulation. Shielding the thoraxes prevented this mode of death at these doses. Kidney injury was judged to be the primary cause of death of all thorax-shielded animals and 15- and 20-Gy thorax-irradiated animals. Animals with kidney damage had elevated PUN and reduced 51Cr-EDTA clearance and hematocrits. The relative merits of each of these end points in assessing radiation-induced kidney injury after total-body exposure are discussed

  13. Temporal dependence of the mass ablation rate in uv irradiated spherical targets

    In this talk, measurements of thermal transport in spherical geometry using time-resolved x-ray spectroscopy are presented. The time dependence of the mass ablation rate (m) is determined by following the progress of the ablation surface through thin layers of material embedded at various depths below the surface of the target. These measurements made with 6, 12 and 24 uv (351 nm) beams from OMEGA are compared to previous thermal transport data and are in qualitative agreement with detailed LILAC hydrodynamic code simulations which predict a sharp decrease in m after the peak of the laser pulse. Viewgraphs of the talk comprise the report

  14. Fe/Ti co-pillared clay for enhanced arsenite removal and photo oxidation under UV irradiation

    Li, Yuan [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Guang Dong Electric Power Design Institute, China Energy Engineering Group Co. Ltd., Guangzhou 510663 (China); Cai, Xiaojiao [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Guo, Jingwei [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); The 718th Research Institute of CSIC, Handan 056027 (China); Zhou, Shimin [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Na, Ping, E-mail: naping@tju.edu.cn [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China)

    2015-01-01

    Graphical abstract: - Highlights: • An iron and titanium co-pillared montmorillonite (Fe-Ti/MMT) was synthesized for arsenite removal. • Variety of characterization results indicated that Fe and Ti species were pillared in MMT. • A possible mechanism of arsenite adsorption/oxidation with UV light was established. • The participation of Fe component can promote the process of photocatalytic oxidation in Fe-Ti/MMT + As(III) system. • Fe-Ti/MMT can function as both photocatalyst and adsorbent for arsenite removal. - Abstract: A series of iron and titanium co-pillared montmorillonites (Fe-Ti/MMT) were prepared using hydrolysis of inserted titanium and different iron content in montmorillonite (MMT). The Fe-Ti/MMT were characterized by X-ray fluorescence, N{sub 2} adsorption and desorption, X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM), confirming the effective insertion of Fe species and TiO{sub 2} in the MMT. The Fe-Ti/MMT was used to remove arsenite (As(III)) from aqueous solutions under different conditions. The result of As(III) adsorption under UV irradiation showed that the photo activity can be enhanced by incorporating Fe and Ti in MMT. Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis indicated that the hydroxyl groups bonded to metal oxide (M–OH) played an important role in the adsorption of As(III)

  15. Photooxidative N-de-ethylation of anionic triarylmethane dye (sulfan blue) in titanium dioxide dispersions under UV irradiation

    The TiO2-mediated photocatalysis process has been successfully applied to degradation of dye pollutants. Our results indicate that the TiO2 surface is negatively charged, and the sulfan blue (SB) adsorbs onto the TiO2 surface through the positive di-ethylamino groups while the TiO2 surface is positively charged and the SB adsorbs onto the TiO2 surface through the negative sulfonyl groups. In order to obtain a better understanding of the mechanistic details of this TiO2-assisted photodegradation of the SB dye with UV irradiation, five intermediates of the processes were separated, identified, and characterized by the HPLC-ESI-MS technique, which included a positive- and negative-ion mode. The results indicated that the N-de-ethylation process continues until the N-de-ethylated SB dye is completely formed. The probable photodegradation pathways were proposed and discussed. The reaction mechanisms of UV/TiO2 proposed in this study should be useful for future applications of the technology to the decolorization of dyes

  16. Photo catalytic Oxidation of Carbon Monoxide over NiO/SnO2 Nano composites under UV Irradiation

    The NiO/SnO2 nano composites have been prepared by the simple coprecipitation method and further characterized by the XRD, SEM, TEM, UV-Vis, and BET. X-ray diffraction (XRD) data analyses indicate the exclusive formation of nano sized particles with rutile-type phase (tetragonal SnO2) for Ni contents below 10 mol%. Only above 10 mol% Ni, the formation of a second NiO-related phase has been determined. The particle size is in the range from 12 to 6 nm. It decreases with increasing amounts of doping NiO. The morphology of NiO-doped SnO2 nanocrystalline powders is spherical, and the distribution of particle size is uniform, as seen from transmission electron microscopy (TEM). The photo catalytic oxidation of CO over NiO/SnO2 photo catalyst has been investigated under UV irradiation. Effects of NiO loading on SnO2, photo catalyst loading, and reaction time on photo catalytic oxidation of CO have been systematically studied. Compared with pure SnO2, the 33.3 mol% NiO/SnO2 composite exhibited approximately twenty fold enhancement of photo catalytic oxidation of CO. Our results provide a method for pollutants removal. Due to simple preparation, high photo catalytic oxidation of CO, and low cost, the NiO/SnO2 photo catalyst will find wide application in the coming future of photo catalytic oxidation of CO

  17. Effects of postthermal treatment and UV irradiation on the structure of titania-polyacrylate nanocomposites

    Tao Wan; Fei Feng; Yuechuan Wang

    2006-01-01

    The effects of postthermal treatment and irradiation time on the structure and thermal stability of TiO2/polyacrylate nanocomposites by a sol-gel process in reverse micelles and subsequent rapid photopolymerization were investigated, and the hybrid films were characterized by thermal gravimetry analysis (TGA), X-ray photoelectron spectrum (XPS), and atomic force microscopy (AFM).XPS data suggested that the prolongation of irradiation time and the postthermal treatment promoted titania formation, with the former affecting more remarkably. TGA data showed that TiO2-hybrid films could upgrade the decomposition onset temperature (Tonset) as well as the temperature at which there is a maximum mass loss rate (Tmax). AFM data demonstrated that the inorganic titania particles with a mean diameter of 25.26-28.84 nm were homogeneously distributed in the organic matrix.

  18. Proton acceleration by high-intensity UV laser irradiation with thin foil targets

    Proton acceleration experiments by irradiation of intense ultra-violet lasers with thin foil targets were conducted. Energies and efficiencies of the accelerated protons were investigated over the target thickness from several μm to 50 nm using various materials. In order to irradiate the very thin foil targets, the discharge pre-amplifier in the previous system was removed to reduce amplified spontaneous emission which disturbed the main pulse interactions. A Thomson parabola ion spectrometer with CR39 plastic nuclear track detectors were used to observe spectra of the accelerated protons. The maximum energies and efficiencies of accelerated protons increased with decreasing the target thickness rather than the product of the density and thickness of the targets. These results were explained by a geometrical effect on hot electron recycling. (author)

  19. [Study of mobile Raman spectroscopy for rapid evaluation of deteriorating of art materials under UV irradiation].

    Luo, Xi-yun; Ye, Fei; Wu, Lai-ming; Yuan, Sheng-wei; Zhang, Wei-bing; Du, Yi-ping

    2010-09-01

    Identification and characterization of materials used in cultural heritage and conservation can provide important information for dating, authentication and deteriorating situation in general. How to extract useful information from these materials in-situ is one of the main concerns. Application of mobile Raman spectroscopy for this purpose has great attentions for scientists and conservators. The present paper aims to investigate the mobile Raman spectroscopy in studying the effect of UV light on the deterioration of silk, seal ink and Chinese traditional colorants such as kermes, vermillion and zhubiao, which is commonly appeared on painted works of art, and the silk sample is also often used as an consolidant for repairing destroyed textile objects. Spectra were recorded from predefined regions on the samples before and after ultraviolet radiation with 360 nm wavelength and 0.68 W x m(-2) intensity. The result revealed obvious effects of ultraviolet radiation on the materials simulated in this research. The original kind of seal ink has been clearly identified. The changes in spectra of all samples with and without UV radiation were further distinguished and studied. The result will assist for scientists and conservators to determine the safe treatments and suitable environmental condition for storage, display and transport. The result will also help for studying mechanism of deterioration of museum objects influenced by environmental factors. The mobile Raman spectroscopy showed a suitable and convenient means for in-situ non-destructive detection and study of deterioration in practical conditions. PMID:21105406

  20. A dicyanotriterpenoid induces cytoprotective enzymes and reduces multiplicity of skin tumors in UV-irradiated mice

    Inducible phase 2 enzymes constitute a primary line of cellular defense. The oleanane dicyanotriterpenoid 2-cyano-3,12-dioxooleana-1,9(11)-dien-28-onitrile (TP-225) is a very potent inducer of these systems. Topical application of TP-225 to SKH-1 hairless mice increases the levels of NAD(P)H-quinone acceptor oxidoreductase 1 (NQO1) and heme oxygenase 1 (HO-1) and protects against UV radiation-induced dermal thickening. Daily topical treatments of 10 nmol of TP-225 to the backs of mice that were previously subjected to low-level chronic UVB radiation (30 mJ/cm2/session, twice a week for 17 weeks), led to 50% reduction in multiplicity of skin tumors. In addition, the total tumor burden of squamous cell carcinomas was reduced by 5.5-fold. The identification of new agents for protection against UV radiation-induced skin cancer and understanding of their mechanism(s) of action is especially important in view of the fact that human skin cancers represent a significant source of increasing morbidity and mortality

  1. ROS mediated crosstalk between endoplasmic reticulum and mitochondria by Phloxine B under environmental UV irradiation.

    Goyal, Shruti; Amar, Saroj Kumar; Srivastav, Ajeet Kumar; Chopra, Deepti; Pal, Manish Kumar; Arjaria, Nidhi; Ray, Ratan Singh

    2016-08-01

    Phloxine B (PhB) is a most commonly used dye in cosmetic products throughout the world. It shows an absorption in visible and ultraviolet radiations. PhB was photodegraded within 4h of UV exposure. It generates reactive oxygen species (ROS) photochemically and intracellularly. Photosensitized PhB caused dose dependent cell viability reduction of human keratinocyte cell line (HaCaT) which was measured through MTT (75.4%) and NRU (77.3%) assays. It also induces cell cycle arrest and DNA damage. Photosensitized PhB induces Ca(2+) release from endoplasmic reticulum (ER). It causes the upregulation of ER stress marker genes ATF6 (1.79 fold) and CHOP (1.93 fold) at transcription levels. The similar response of ATF6 (3.6 fold) and CHOP (2.38 fold) proteins was recorded at translation levels. CHOP targeted the mitochondria and reduced the mitochondrial membrane potential analyzed through JC-1 staining. It further increases Bax/Bcl2 ratio (3.58 fold) and promotes the release of cytochrome c, finally leads to caspase-dependent apoptosis. Upregulation of APAF1 (1.79 fold) in PhB treated cells under UV B exposure supports the mitochondrial-mediated apoptotic cell death. The results support the involvement of ER and mitochondria in ROS mediated PhB phototoxicity. Therefore, the use of PhB in cosmetic products may be deleterious to users during sunlight exposure. PMID:27288659

  2. Study of high density polyethylene under UV irradiation or mechanical stress by fluorescence spectroscopy

    Due to their diversity and their wide range of applications, polymers have emerged in our environment. For technical applications, these materials can be exposed to aggressive environment leading to an alteration of their properties. The effects of this degradation are linked to the concept of life duration, corresponding to the time required for a property to reach a threshold below which the material becomes unusable. Monitoring the ageing of polymer materials constitute a major challenge. Fluorescence spectroscopy is a technique able to provide accurate information concerning this issue. In this study, emphasis was placed on the use of fluorescence spectroscopy to study the phenomena involved in either the UV radiation or mechanical stresses of a polymer. In the case of high density polyethylene, the lack of intrinsic fluorescent signal leads to the use of a dye. This dye gives a fluorescent response depending on its microenvironment. All modifications in the macromolecular chain generate a shift of the fluorescent peak. This work can be dissociated in two major parts, on one hand the influence of UV aging on the fluorescent response and in another hand the influence of mechanical stresses. In the first part, complementary analyses like FTIR or DSC are used to correlate fluorescent results with known photo degradation mechanisms. The results show the great sensibility of the technique to the microstructural rearrangement in the polymer. In the second part, the dependence between the stress and the fluorescence emission gives opportunity to evaluate internal stresses in the material during cyclic solicitations. (author)

  3. Effects of acute and chronic gamma irradiation on the shoot apex and general morphology of Lupinus albus L

    Lupinus albus L. plants were grown from seeds and irradiated at various stages of development with acute or chronic gamma rays. All plants were greenhouse grown (pre- and post-irradiation) and allowed to proceed through their normal growth cycle. The purpose of these experiments was to establish a Plactochron Index for Lupinus albus L. and to determine the effects of acute and chronic irradiation on development at the macro and microscopic levels. A Plastochron Index was calculated and used as an indirect time scale to evaluate the effects of gamma rays from a common base line. Acute radiation treatment lasted for a period of a few days, whereas chronic treatment was initiated at the seedling stage and lasted for the entire growth season. Vegetative plants were used to study the effects of acute radiation exposure on apical meristem morphology, Plastochron Index, phyllatoxis and gross morphology

  4. Microwave thermographic measures after acute localized irradiation in pigs: acquisition and analysis methods

    The determination of the size and intensity of a radiolesion after an acute localized irradiation has not yet found an adequate solution by clinicians, in spite of using telethermography and vascular scintigraphy methods. By taking the pig as an experimental model, whose skin and muscle closely resemble those of man, we tested a new atraumatic investigation method i.e. microwave thermography, after acute localized irradiation on the thigh. From a qualitative point of view thermographic images enabled us to delimit thermal reaging areas and to follow inflammatory rises even in the absence of obvious erythematous reactions. Further quantitative studies demonstrated a dose-effect relationship (dose versus thermal reaction intensity) between 30 and 84 Gy. Comparison of superficial measurements using a thermistance on the one hand, and deep measurements with a 3gHz microwave probe on the other hand, enabled us to discriminate between low levels (30-40 Gy) of irradiation leading to self-healing lesions, and high level ones (64-84 Gy) which will induce a large necrotized area as well as a persistent ulcer

  5. Pediatric Craniospinal Axis Irradiation With Helical Tomotherapy: Patient Outcome and Lack of Acute Pulmonary Toxicity

    Purpose: To present the patient outcomes and risk of symptomatic acute radiation pneumonitis (ARP) in 18 pediatric patients treated with helical tomotherapy to their craniospinal axis for a variety of neoplasms. Methods and Materials: A total of 18 patients received craniospinal axis irradiation with helical tomotherapy. The median age was 12 years (range, 2.5-21). The follow-up range was 3-48 months (median, 16.5). Of the 18 patients, 15 received chemotherapy in the neoadjuvant, adjuvant, or concomitant setting. Chemotherapy was tailored to the particular histologic diagnosis; 10 of 18 patients underwent surgical removal of the gross primary tumor. The patients were followed and evaluated for ARP starting at 3-6 months after completion of craniospinal axis irradiation. ARP was graded using the Common Toxicity Criteria, version 3. Results: At the last follow-up visit, 14, 2, and 2 patients were alive without disease, alive with disease, and dead of disease, respectively. The cause-specific survival rate was 89% (16 of 18), disease-free survival rate was 78% (14 of 18), and overall survival rate was 89% (16 of 18). No patient had treatment failure at the cribriform plate. No patient developed symptoms of ARP. Conclusion: Craniospinal axis irradiation using helical tomotherapy yielded encouraging patient outcomes and acute toxicity profiles. Although large volumes of the lung received low radiation doses, no patient developed symptoms of ARP during the follow-up period.

  6. Formic acid enhanced effective degradation of methyl orange dye in aqueous solutions under UV-Vis irradiation.

    Wang, Jingjing; Bai, Renbi

    2016-09-15

    Developing efficient technologies to treat recalcitrant organic dye wastewater has long been of great research and practical interest. In this study, a small molecule, formic acid (FA), was applied as a process enhancer for the degradation of methyl orange (MO) dye as a model recalcitrant organic pollutant in aqueous solutions under the condition of UV-Vis light irradiation and air aeration at the ambient temperature of 25 °C. It was found that the decolouration of the dye solutions can be rapidly achieved, reducing the time, for example, from around 17.6 h without FA to mostly about less than 2 h with the presence of FA. The mineralization rate of MO dye reached as high as 81.8% in 1.5 h in the case of initial MO dye concentration at 25 mg L(-1), which is in contrast to nearly no mineralization of the MO dye for a similar system without the FA added. The study revealed that the generation of the H2O2 species in the system was enhanced and the produced OH radicals effectively contributed to the degradation of the MO dye. Process parameters such as the initial concentration of MO dye, FA dosage and solution pH were all found to have some effect on the degradation efficiency under the same condition of UV-Vis light irradiation and air aeration. The MO dye degradation performance was found to follow a first-order reaction rate to the MO dye concentration in most cases and there existed a positive correlation between the reaction rate constant and the initial FA concentration. Compared to the traditional H2O2/UV-Vis oxidation system, the use of FA as a process-enhancing agent can have the advantages of low cost, easy availability, and safe to use. The study hence demonstrates a promising approach to use a readily available small molecule of FA to enhance the degradation of recalcitrant organic pollutants, such as MO dye, especially for their pre-treatment. PMID:27258621

  7. Comparison of the Organic Composition of Cometary Samples with Residues Formed from the UV Irradiation of Astrophysical Ice Analogs

    Milam, S. N.; Nuevo, M.; Sandford, S. A.; Cody, G. D.; Kilcoyne, A. L. D.; Stroud, R. M.; DeGregorio, B. T.

    2010-01-01

    The NASA Stardust mission successfully collected material from Comet 81P/Wild 2 [1], including authentic cometary grains [2]. X-ray absorption near-edge structure (XANES) spectroscopy analysis of these samples indicates the presence of oxygen-rich and nitrogen-rich organic materials, which contain a broad variety of functional groups (carbonyls, C=C bonds, aliphatic chains, amines, arnides, etc.) [3]. One component of these organics appears to contain very little aromatic carbon and bears some similarity to the organic residues produced by the irradiation of ices of interstellar/cometary composition, Stardust samples were also recently shown to contain glycine, the smallest biological amino acid [4]. Organic residues produced froth the UV irradiation of astrophysical ice analogs are already known to contain a large suite of organic molecules including amino acids [5-7], amphiphilic compounds (fatty acids) [8], and other complex species. This work presents a comparison between XANES spectra measured from organic residues formed in the laboratory with similar data of cometary samples collected by the Stardust mission

  8. Ornaments in radiation treatment of cultural heritage: Color and UV-vis spectral changes in irradiated nacres

    Marušić, Katarina; Pucić, Irina; Desnica, Vladan

    2016-07-01

    Cultural heritage objects that are radiation treated in order to stop their biodegradation often contain ornamenting materials that cannot be removed. Radiation may produce unwanted changes to such materials. Nacre is a common ornamenting material so this is an attempt to assess the impact of gamma-radiation on its optical properties. Two types of nacre (yellow and white) were obtained from a museum and subjected to different absorbed doses of Co-60 gamma irradiation under the same conditions. The radiation induced changes of nacres color were investigated with fiber optic reflectance spectroscopy (FORS). Colorimetry in CIE Lab space revealed that in both nacres the lightness shifted to darker grey hues at high doses while the color component's (red, green, yellow and blue) behavior depended on the nacre type. Observable changes occurred at doses much above the dose range needed for radiation treatment of cultural heritage objects that are often ornamented with nacre. In UV-vis reflectance spectra of samples irradiated to high doses carbonate radical anion absorption appeared.

  9. Low Doses of Oxygen Ion Irradiation Cause Acute Damage to Hematopoietic Cells in Mice.

    Chang, Jianhui; Luo, Yi; Wang, Yingying; Pathak, Rupak; Sridharan, Vijayalakshmi; Jones, Tamako; Mao, Xiao Wen; Nelson, Gregory; Boerma, Marjan; Hauer-Jensen, Martin; Zhou, Daohong; Shao, Lijian

    2016-01-01

    One of the major health risks to astronauts is radiation on long-duration space missions. Space radiation from sun and galactic cosmic rays consists primarily of 85% protons, 14% helium nuclei and 1% high-energy high-charge (HZE) particles, such as oxygen (16O), carbon, silicon, and iron ions. HZE particles exhibit dense linear tracks of ionization associated with clustered DNA damage and often high relative biological effectiveness (RBE). Therefore, new knowledge of risks from HZE particle exposures must be obtained. In the present study, we investigated the acute effects of low doses of 16O irradiation on the hematopoietic system. Specifically, we exposed C57BL/6J mice to 0.1, 0.25 and 1.0 Gy whole body 16O (600 MeV/n) irradiation and examined the effects on peripheral blood (PB) cells, and bone marrow (BM) hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs) at two weeks after the exposure. The results showed that the numbers of white blood cells, lymphocytes, monocytes, neutrophils and platelets were significantly decreased in PB after exposure to 1.0 Gy, but not to 0.1 or 0.25 Gy. However, both the frequency and number of HPCs and HSCs were reduced in a radiation dose-dependent manner in comparison to un-irradiated controls. Furthermore, HPCs and HSCs from irradiated mice exhibited a significant reduction in clonogenic function determined by the colony-forming and cobblestone area-forming cell assays. These acute adverse effects of 16O irradiation on HSCs coincided with an increased production of reactive oxygen species (ROS), enhanced cell cycle entry of quiescent HSCs, and increased DNA damage. However, none of the 16O exposures induced apoptosis in HSCs. These data suggest that exposure to low doses of 16O irradiation induces acute BM injury in a dose-dependent manner primarily via increasing ROS production, cell cycling, and DNA damage in HSCs. This finding may aid in developing novel strategies in the protection of the hematopoietic

  10. Low Doses of Oxygen Ion Irradiation Cause Acute Damage to Hematopoietic Cells in Mice.

    Jianhui Chang

    Full Text Available One of the major health risks to astronauts is radiation on long-duration space missions. Space radiation from sun and galactic cosmic rays consists primarily of 85% protons, 14% helium nuclei and 1% high-energy high-charge (HZE particles, such as oxygen (16O, carbon, silicon, and iron ions. HZE particles exhibit dense linear tracks of ionization associated with clustered DNA damage and often high relative biological effectiveness (RBE. Therefore, new knowledge of risks from HZE particle exposures must be obtained. In the present study, we investigated the acute effects of low doses of 16O irradiation on the hematopoietic system. Specifically, we exposed C57BL/6J mice to 0.1, 0.25 and 1.0 Gy whole body 16O (600 MeV/n irradiation and examined the effects on peripheral blood (PB cells, and bone marrow (BM hematopoietic stem cells (HSCs and hematopoietic progenitor cells (HPCs at two weeks after the exposure. The results showed that the numbers of white blood cells, lymphocytes, monocytes, neutrophils and platelets were significantly decreased in PB after exposure to 1.0 Gy, but not to 0.1 or 0.25 Gy. However, both the frequency and number of HPCs and HSCs were reduced in a radiation dose-dependent manner in comparison to un-irradiated controls. Furthermore, HPCs and HSCs from irradiated mice exhibited a significant reduction in clonogenic function determined by the colony-forming and cobblestone area-forming cell assays. These acute adverse effects of 16O irradiation on HSCs coincided with an increased production of reactive oxygen species (ROS, enhanced cell cycle entry of quiescent HSCs, and increased DNA damage. However, none of the 16O exposures induced apoptosis in HSCs. These data suggest that exposure to low doses of 16O irradiation induces acute BM injury in a dose-dependent manner primarily via increasing ROS production, cell cycling, and DNA damage in HSCs. This finding may aid in developing novel strategies in the protection of the

  11. DNA damage focus analysis in blood samples of minipigs reveals acute partial body irradiation.

    Andreas Lamkowski

    Full Text Available Radiation accidents frequently involve acute high dose partial body irradiation leading to victims with radiation sickness and cutaneous radiation syndrome that implements radiation-induced cell death. Cells that are not lethally hit seek to repair ionizing radiation (IR induced damage, albeit at the expense of an increased risk of mutation and tumor formation due to misrepair of IR-induced DNA double strand breaks (DSBs. The response to DNA damage includes phosphorylation of histone H2AX in the vicinity of DSBs, creating foci in the nucleus whose enumeration can serve as a radiation biodosimeter. Here, we investigated γH2AX and DNA repair foci in peripheral blood lymphocytes of Göttingen minipigs that experienced acute partial body irradiation (PBI with 49 Gy (± 6% Co-60 γ-rays of the upper lumbar region. Blood samples taken 4, 24 and 168 hours post PBI were subjected to γ-H2AX, 53BP1 and MRE11 focus enumeration. Peripheral blood lymphocytes (PBL of 49 Gy partial body irradiated minipigs were found to display 1-8 DNA damage foci/cell. These PBL values significantly deceed the high foci numbers observed in keratinocyte nuclei of the directly γ-irradiated minipig skin regions, indicating a limited resident time of PBL in the exposed tissue volume. Nonetheless, PBL samples obtained 4 h post IR in average contained 2.2% of cells displaying a pan-γH2AX signal, suggesting that these received a higher IR dose. Moreover, dispersion analysis indicated partial body irradiation for all 13 minipigs at 4 h post IR. While dose reconstruction using γH2AX DNA repair foci in lymphocytes after in vivo PBI represents a challenge, the DNA damage focus assay may serve as a rapid, first line indicator of radiation exposure. The occurrence of PBLs with pan-γH2AX staining and of cells with relatively high foci numbers that skew a Poisson distribution may be taken as indicator of acute high dose partial body irradiation, particularly when samples are available

  12. Defect creation under UV irradiation of CsI:Pb crystals in Pb 2+ -induced absorption bands investigated by luminescence methods

    Babin, V.; Kalder, K.; Krasnikov, A.; Nikl, Martin; Nitsch, Karel; Zazubovich, S.

    2002-01-01

    Roč. 234, č. 2 (2002), s. 689-700. ISSN 0370-1972 Grant ostatní: NATO(XX) SfP 973510 Institutional research plan: CEZ:AV0Z1010914 Keywords : CsI:Pb crystal * luminescence * thermoluminescence * defect creation * UV irradiation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.930, year: 2002

  13. The influence of chemical post-etching and UV irradiation on the optical absorption and thermal diffusivity of porous silicon studied by photoacoustic technique

    We applied a photoacoustic (PA) technique to study the optical absorption and thermal diffusivity of porous silicon (PSi) samples. The PSi layers were formed on p-type Si wafers in an HF electrolyte. Three kinds of PSi samples that had undergone chemical post-etching were studied before and after UV irradiation for 2 h. We observed that a strong confinement effect occurred in all of the PSi samples from the blue shift of the band gap energy compared with that of crystalline Si, while the effective thermal diffusivities were almost two orders of the magnitude smaller than that of conventional Si crystals. The band gap shifted to higher energy and the effective thermal diffusivity decreased as the post-etching time increased. In the case of a PSi sample that was not chemically post-etched, the optical absorption and effective thermal diffusivity before and after UV irradiation were almost unchanged. However, for the PSi samples that were chemically post-etched, the optical absorption decreased and the effective thermal diffusivity increased after UV irradiation. This indicates that PSi samples that are post-etched are more readily affected by UV irradiation, i.e., oxidized by replacing Si-H x bonds by Si-O x, than those that do not undergo post-etching

  14. Growth responses of Vigna radiata seeds to laser irradiation in the UV-A region

    We have investigated the effect of pulsed nitrogen laser radiation (337.1 nm) on morphological characteristics and biochemical contents in seedlings from treated greengram (Vigna radiata L.) seeds, which were germinated and grown in Petri dishes for a week. The shoot and root lengths, and fresh and dry weights of the seedlings were maximum with the 30 min exposure, while protein was maximum with 20 min, RNA and DNA contents with 5 min exposure time. Chlorophyll content was not affected by the irradiation

  15. Atomic force microscopy analysis of human cornea surface after UV (λ=266 nm) laser irradiation

    Spyratou, E.; Makropoulou, M.; Moutsouris, K.; Bacharis, C.; Serafetinides, A. A.

    2009-07-01

    Efficient cornea reshaping by laser irradiation for correcting refractive errors is still a major issue of interest and study. Although the excimer laser wavelength of 193 nm is generally recognized as successful in ablating corneal tissue for myopia correction, complications in excimer refractive surgery leads to alternative laser sources and methods for efficient cornea treatment. In this work, ablation experiments of human donor cornea flaps were conducted with the 4th harmonic of an Nd:YAG laser, with different laser pulses. AFM analysis was performed for examination of the ablated cornea flap morphology and surface roughness.

  16. Photodegradation of the indoor organic pollutants by UV irradiation using TiO2 catalysts

    Glajar, Ioana C.; Moldovan, Z.

    2009-08-01

    Volatile organic compounds (VOCs) are a major environmental concern, because of their carcinogenic and toxic effects on human health. The most frequent types of VOCs found in indoor air are, according to literature, Choloroform, p-dichlorbenzene, tetrachloroethylene, formaldehyde, NOx. Another VOCs found very often mentioned in the literature are ethanol and acetone or BTEX compounds. The investigated compounds used in this work for studding the photodegradation effect are toluene and cholorobenzene. In the present work were calculated the photodegradation rates of the compounds mentioned above using UV radiation and TiO2, as catalyst. The obtained results are discussed based on comparative values of removal quantities for few time intervals for different types of catalysts based on TiO2 aerogel.

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

    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.

  18. Alterations in composition of sterols and in properties of erythrocyte membranes in rats with Shvetz experimental leukosis and after UV irradiation

    Palamarchyuk, V.I.; Trikash, I.O. (AN Ukrainskoj SSR, Kiev. Inst. Biokhimii)

    1983-05-01

    Sterol composition of erythrocyte membrane is studied in experimental Schwetz leukosis. Interconnections of alteration in sterol composition and membrane properties are investigated, as well as the effect of UV-radiation on the alteration of sterol composition of erythrocyte membrane and lifetime of animals With leukosis. The effect of UV-radiation on survival of the leukosis animals has been studied which showed that irradiation of rats in the dose of 8 mWt/min/cm/sup 2/ for 12 days increases the lifetime of animals by several days, i.e. increases resistance of animals to leukosis. In the case of short-time UV-radiation of rats the cholesterine amount in erythrocyte membranes increases by 9% as compared with the norm, simultaneously, other substances appear. Acidic resistance of erythrocytes of irradiated animals also increases. The supposition is made that alterations promote the increase of organism resistance to leukosis.

  19. Alterations in composition of sterols and in properties of erythrocyte membranes in rats with Shvetz experimental leukosis and after UV irradiation

    Sterol composition of erythrocyte membrane is studied in experimental Schwetz leukosis. Interconnections of alteration in sterol composition and membrane properties are investigated, as well as the effect of UV-radiation on the alteration of sterol composition of erythrocyte membrane and lifetime of animals With leukosis. The effect of UV-radiation on survival of the leukosis animals has been studied which showed that irradiation of rats in the dose of 8 mWt/min/cm2 for 12 days increases the lifetime of animals by several days, i.e. increases resistance of animals to leukosis. In the case of short-time UV-radiation of rats the cholesterine amount in erythrocyte membranes increases by 9% as compared with the norm, simultaneously, other substances appear. Acidic resistance of erythrocytes of irradiated animals also increases. The supposition is made that alterations promote the increase of organism resistance to leukosis

  20. Photo-alignment of low-molecular mass nematic liquid crystals on photochemically bifunctional chalcone-epoxy film by irradiation of a linearly polarized UV light

    Photocrosslinkable chalcone-epoxy compound comprising 1,3-bis-(4-hydroxy-phenyl)-propenone was synthesized for fabricating the photo-alignment layer of liquid crystals. Chalcone group was introduced into the main chain unit of the epoxy oligomer. We observed a photodimerization behavior and an optical anisotropy of this material by irradiation of a linearly polarized UV(LP-UV) light. With a trace amount of cationic photo initiator (TRS-HFA), polymerization of epoxy groups was also conducted at the similar wavelength range used for photodimerization . Linearly polarized UV irradiation on the chalcone-epoxy films with cationic photoinitiator induced optical anisotropy of the film and the resultant film can be used for alignment layers for low molecular weight nematic liquid crystals

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

    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).

  2. Mineral oxides change the atmospheric reactivity of soot: NO2 uptake under dark and UV irradiation conditions.

    Romanias, Manolis N; Bedjanian, Yuri; Zaras, Aristotelis M; Andrade-Eiroa, Aurea; Shahla, Roya; Dagaut, Philippe; Philippidis, Aggelos

    2013-12-01

    The heterogeneous reactions between trace gases and aerosol surfaces have been widely studied over the past decades, revealing the crucial role of these reactions in atmospheric chemistry. However, existing knowledge on the reactivity of mixed aerosols is limited, even though they have been observed in field measurements. In the current study, the heterogeneous interaction of NO2 with solid surfaces of Al2O3 covered with kerosene soot was investigated under dark conditions and in the presence of UV light. Experiments were performed at 293 K using a low-pressure flow-tube reactor coupled with a quadrupole mass spectrometer. The steady-state uptake coefficient, γ(ss), and the distribution of the gas-phase products were determined as functions of the Al2O3 mass; soot mass; NO2 concentration, varied in the range of (0.2-10) × 10(12) molecules cm(-3); photon flux; and relative humidity, ranging from 0.0032% to 32%. On Al2O3/soot surfaces, the reaction rate was substantially increased, and the formation of HONO was favored compared with that on individual pure soot and pure Al2O3 surfaces. Uptake of NO2 was enhanced in the presence of H2O under both dark and UV irradiation conditions, and the following empirical expressions were obtained: γ(ss,BET,dark) = (7.3 ± 0.9) × 10(-7) + (3.2 ± 0.5) × 10(-8) × RH and γ(ss,BET,UV) = (1.4 ± 0.2) × 10(-6) + (4.0 ± 0.9) × 10(-8) × RH. Specific experiments, with solid sample preheating and doping with polycyclic aromatic hydrocarbons (PAHs), showed that UV-absorbing organic compounds significantly affect the chemical reactivity of the mixed mineral/soot surfaces. A mechanistic scheme is proposed, in which Al2O3 can either collect electrons, initiating a sequence of redox reactions, or prevent the charge-recombination process, extending the lifetime of the excited state and enhancing the reactivity of the organics. Finally, the atmospheric implications of the observed results are briefly discussed. PMID:24188183

  3. Carbamic acid and carbamate formation in NH{3}:CO{2} ices - UV irradiation versus thermal processes

    Bossa, J. B.; Theulé, P.; Duvernay, F.; Borget, F.; Chiavassa, T.

    2008-12-01

    Context: We study carbamic acid [ NH{2}COOH] and ammonium carbamate [ NH{2}COO-] [ NH{4}+] formation in interstellar ice analogs. Aims: We demonstrate how carbamic acid [ NH{2}COOH] and ammonium carbamate [ NH{2}COO-] [ NH{4}+] can be formed from both thermal reactions and energetic photons in an NH{3}:CO{2} ice mixture. Methods: Infrared and mass spectroscopy are used to monitor NH{3}:CO{2} ice mixture evolution during both warming and VUV photon irradiation. Results: Carbamic acid and ammonium carbamate can be produced thermally in a 1:1 ratio from NH{3} and CO{2} above 80 K. They can be also formed in a 28:1 ratio by less efficient processes such as energetic photons. Our study and its results provide fresh insight into carbamic acid formation in interstellar ices. Conclusions: We demonstrate that care is required to separate irradiation-induced reactivity from purely thermal reactivity in ices in which ammonia and carbon dioxide are both present. From an interstellar chemistry point of view, carbamic acid and ammonium carbamate are readily produced from the ice mantle of a typical interstellar grain and should therefore be a detectable species in molecular clouds.

  4. Plasmatic and thermographic consequences of local acute irradiation; a qualitative and quantitative analysis in the pig

    Acute phase reactant proteins associated with thermographic measurements and enzymatic activity assays in plasma were carried out on 39 pigs, following local exposure of the thigh to a collimated source of iridium 192 at doses ranging between 30 and 84 Gy (2 cm depth dose). The inflammatory response after irradiation, from day 1 to day 30 was accompanied by plasma protein changes associated with an elevation of local and general temperatures in irradiated animals. Degenerative processes in muscle led to an increase of plasmatic creatine kinase and lactate-dehydrogenase. Results were developed qualitatively (distribution pattern of proteins, thermographic measurements, enzymatic activities and clinical evolution of the lesions) and qualitatively (plasma level of creatine kinase versus applied radiation doses and pharmalogical treatments)

  5. Mitochondrial DNA alterations of peripheral lymphocytes in acute lymphoblastic leukemia patients undergoing total body irradiation therapy

    Mitochondrial DNA (mtDNA) alterations, including mtDNA copy number and mtDNA 4977 bp common deletion (CD), are key indicators of irradiation-induced damage. The relationship between total body irradiation (TBI) treatment and mtDNA alterations in vivo, however, has not been postulated yet. The aim of this study is to analyze mtDNA alterations in irradiated human peripheral lymphocytes from acute lymphoblastic leukemia (ALL) patients as well as to take them as predictors for radiation toxicity. Peripheral blood lymphocytes were isolated from 26 ALL patients 24 hours after TBI preconditioning (4.5 and 9 Gy, respectively). Extracted DNA was analyzed by real-time PCR method. Average 2.31 times mtDNA and 0.53 fold CD levels were observed after 4.5 Gy exposure compared to their basal levels. 9 Gy TBI produced a greater response of both mtDNA and CD levels than 4.5 Gy. Significant inverse correlation was found between mtDNA content and CD level at 4.5 and 9 Gy (P = 0.037 and 0.048). Moreover, mtDNA content of lymphocytes without irradiation was found to be correlated to age. mtDNA and CD content may be considered as predictive factors to radiation toxicity

  6. Mitochondrial DNA alterations of peripheral lymphocytes in acute lymphoblastic leukemia patients undergoing total body irradiation therapy

    Ji Fuyun

    2011-10-01

    Full Text Available Abstract Background Mitochondrial DNA (mtDNA alterations, including mtDNA copy number and mtDNA 4977 bp common deletion (CD, are key indicators of irradiation-induced damage. The relationship between total body irradiation (TBI treatment and mtDNA alterations in vivo, however, has not been postulated yet. The aim of this study is to analyze mtDNA alterations in irradiated human peripheral lymphocytes from acute lymphoblastic leukemia (ALL patients as well as to take them as predictors for radiation toxicity. Methods Peripheral blood lymphocytes were isolated from 26 ALL patients 24 hours after TBI preconditioning (4.5 and 9 Gy, respectively. Extracted DNA was analyzed by real-time PCR method. Results Average 2.31 times mtDNA and 0.53 fold CD levels were observed after 4.5 Gy exposure compared to their basal levels. 9 Gy TBI produced a greater response of both mtDNA and CD levels than 4.5 Gy. Significant inverse correlation was found between mtDNA content and CD level at 4.5 and 9 Gy (P = 0.037 and 0.048. Moreover, mtDNA content of lymphocytes without irradiation was found to be correlated to age. Conclusions mtDNA and CD content may be considered as predictive factors to radiation toxicity.

  7. The use of chromosomic anomalies for the estimation of an accidental acute irradiation dose in man

    The induction of chromosome abnormalities (dicentrics, rings and fragments) in human blood samples subjected to cobalt 60 gamma irradiation was studied for 11 doses varying from 25 to 1800 rads. The chromosome aberrations were counted in lymphocytes after 48 hours of in vitro culture. The results obtained from the observation of 6400 cells made it possible to establish dose-effect relationships for each types of abnormality (dicentrics, dicentrics and rings, and fragments). The dose-effect relationships were used to estimate doses received by 9 workers submitted to relatively homogeneous global acute irradiation and for which an evaluation of the average absorbed dose was possible. There is in general a good agreement between the estimation of the average absorbed dose based on chromosome damage and the physical dosimeter data. The study of the time-dependent evolution of the chromosome abnormalities in the lymphocytes of irradiated subjects shows that dosimetric estimations based on lymphocyte chromosome abnormalities in human blood are valid for several weeks after irradiation

  8. Total body irradiation and syngeneic marrow transplantation in an inbred rat model of acute myelogenous leukemia

    While acute myelogenous leukemia (AML) occurs rarely in laboratory animals, over 20 model systems have been reported. One of these, AML of the inbred Wistar/Furth rat, has been shown to be pathophysiologically similar to human AML. Ten days after intravenous inoculation of 1.0 x 106 cells of a tissue culture grown clonal line, rats demonstrated peripheral blood leukemia, replacement of greater than 90% of the bone marrow with distinctive malignant myeloblasts and a syndrome of hypermuramidase (lysozyme) emia and muramidasuria. Total body irradiation (TBI) at 10 days after leukemia cell passage with a marrow lethal dose (950 rad, 140 rad/min, 137Cs source, 663 kV) followed by intravenous inoculation of 5.0 x 108/kg viable syngeneic bone marrow cells produced transient complete remissions. Repopulation with transplanted marrow was detected along with increasing numbers of recognizable W/Fu AML cells in peripheral blood, marrow, and central nervous system. The delayed leukemia relapse in irradiated transplanted rats compared to irradiated non-transplanted controls suggests an interaction between surviving W/Fu AML cells and transplanted marrow. This model may be of value in studies designing a therapeutic interaction against AML by donor marrow in the chemotherapy, immunotherapy, and total body irradiated patient

  9. Acute Radiation Syndrome Severity Score System in Mouse Total-Body Irradiation Model.

    Ossetrova, Natalia I; Ney, Patrick H; Condliffe, Donald P; Krasnopolsky, Katya; Hieber, Kevin P

    2016-08-01

    Radiation accidents or terrorist attacks can result in serious consequences for the civilian population and for military personnel responding to such emergencies. The early medical management situation requires quantitative indications for early initiation of cytokine therapy in individuals exposed to life-threatening radiation doses and effective triage tools for first responders in mass-casualty radiological incidents. Previously established animal (Mus musculus, Macaca mulatta) total-body irradiation (γ-exposure) models have evaluated a panel of radiation-responsive proteins that, together with peripheral blood cell counts, create a multiparametic dose-predictive algorithm with a threshold for detection of ~1 Gy from 1 to 7 d after exposure as well as demonstrate the acute radiation syndrome severity score systems created similar to the Medical Treatment Protocols for Radiation Accident Victims developed by Fliedner and colleagues. The authors present a further demonstration of the acute radiation sickness severity score system in a mouse (CD2F1, males) TBI model (1-14 Gy, Co γ-rays at 0.6 Gy min) based on multiple biodosimetric endpoints. This includes the acute radiation sickness severity Observational Grading System, survival rate, weight changes, temperature, peripheral blood cell counts and radiation-responsive protein expression profile: Flt-3 ligand, interleukin 6, granulocyte-colony stimulating factor, thrombopoietin, erythropoietin, and serum amyloid A. Results show that use of the multiple-parameter severity score system facilitates identification of animals requiring enhanced monitoring after irradiation and that proteomics are a complementary approach to conventional biodosimetry for early assessment of radiation exposure, enhancing accuracy and discrimination index for acute radiation sickness response categories and early prediction of outcome. PMID:27356057

  10. Technical relapsed testicular irradiation for acute lymphoblastic leukemia; Tecnica de irradiacion para testiculos en recidiva de leucemia linfoblastica aguda

    Velazquez Miranda, S.; Delgado Gil, M. M.; Ortiz Siedel, M.; Munoz Carmona, D. M.; Gomez-Barcelona, J.

    2011-07-01

    Testicular irradiation in children suffering from acute lymphoblastic leukemia presents difficulties in relation to daily positioning, dosimetry for dose homogenization of complex geometry and volume change during irradiation thereof. This can lead to significant deviations from the prescribed doses. In addition, the usual techniques often associated with unnecessary irradiation of pelvic simphysis, anus and perineum. This, in the case of pediatric patients, is of great importance, since doses in the vicinity of 20 Gy are associated with a deviation of bone growth, low testosterone levels around 24 Gy and high rates of generation of second tumors. To overcome these problems we propose a special restraint in prone and non-coplanar irradiation.

  11. Time variations of solar UV irradiance as measured by the SOLSTICE (UARS) instrument

    London, Julius; Rottman, Gary J.; Woods, Thomas N.; Wu, Fie

    1993-01-01

    An analysis is presented of solar ultraviolet irradiance measurements made by the SOLSTICE spectrometers on the Upper Atmosphere Research Satellite (UARS). Reported observations cover the wavelength interval 119-420 nm, and the analysis discussed here is for the time period 26 Nov 1991 to 31 Dec 1992, during which time solar activity decreased in intensity. At the time of peak activity, the average 27-day variation had a relative amplitude of about 8 percent at Ly-alpha, tailing off to about 0.6 percent at 260 nm. It is shown that over the spectral interval 119-260 nm, the relative 27-day harmonic was about a factor of two larger during the strongly disturbed as compared with the moderately disturbed period.

  12. Solid surface photochemistry of montmorillonite: mechanisms for the arsenite oxidation under UV-A irradiation.

    Yuan, Yanan; Wang, Yajie; Ding, Wei; Li, Jinjun; Wu, Feng

    2016-01-01

    Transformation of inorganic arsenic species has drawn great concern in recent decades because of worldwide and speciation-dependent pollution and the hazards that they pose to the environment and to human health. As(III) photooxidation in aquatic systems has received much attention, but little is known about photochemical transformation of arsenic species on top soil. As(III) photooxidation on natural montmorillonite under UV-A radiation was investigated by using a moisture- and temperature-controlled photochemical chamber with two black-light lamps. Initial As(III) concentration, pH, layer thickness, humic acid (HA) concentration, the presence of additional iron ions, and the contribution of reactive oxygen species (ROS) were examined. The results show that pH values of the clay layers greatly influenced As(III) photooxidation on montmorillonite. As(III) photooxidation followed the Langmuir-Hinshelwood model. HA and additional iron ions greatly promoted photooxidation, but excess Fe(II) competed with As(III) for oxidation by ROS. Scavenging experiments revealed that natural montmorillonite induced the conversion of As(III) to As(V) by generating ROS (mainly HO(•) and HO2(•)/O2(•-)) and that HO(•) radical was the predominant oxidant in this system. Our work demonstrates that photooxidation on the surface of natural clay minerals in top soil can be important to As(III) transformation. This allows understanding and predicting the speciation and behavior of arsenic on the soil surface. PMID:26194238

  13. Effects of TiO2 nanoparticles on ROS production and growth inhibition using freshwater green algae pre-exposed to UV irradiation.

    Fu, Ling; Hamzeh, Mahsa; Dodard, Sabine; Zhao, Yuan H; Sunahara, Geoffrey I

    2015-05-01

    This study investigated the possibility that titanium dioxide nanoparticles (nano-TiO2) toxicity in Pseudokirchneriella subcapitata involves reactive oxygen species (ROS) production, using the dichlorodihydrofluorescein (DCF) assay. Algae were exposed to nano-TiO2 under laboratory fluorescent lamps supplemented with UV irradiation for 3h, with or without a UV filter. Results showed that nano-TiO2 increased ROS production in UV-exposed cells, with or without a UV filter (LOEC values were 250 and 10mg/L, respectively). Sublethal effects of nano-TiO2 on UV pre-exposed algae were also examined. Toxicity studies indicated that exposure to nano-TiO2 agglomerates decreased algal growth following 3h pre-exposure to UV, with or without a UV filter (EC50s were 8.7 and 6.3mg/L, respectively). The present study suggests that the growth inhibitory effects of nano-TiO2 in algae occurred at concentrations lower than those that can elevate DCF fluorescence, and that ROS generation is not directly involved with the sublethal effects of nano-TiO2 in algae. PMID:25867689

  14. Acute effects of gamma irradiation on vascular arterial tone; Effets aigus d`une irradiation gamma sur le tonus vasculaire arteriel

    Bourlier, V.; Diserbo, M.; Multon, E.; Verdetti, J.; Fatome, M.

    1995-12-31

    In rat aortic rings, we showed an increase in arterial tone during irradiation. This effect is acute reversible. This effect is only observed on pre-contracted rings and needs the integrity of vascular endothelium. The molecular mechanism of this effect is discussed. (author). 4 refs.

  15. Detection of monohydroxyeicosatetraenoic acids and F2-isoprostanes in microdialysis samples of human UV-irradiated skin by gas chromatography-mass spectrometry.

    Grundmann, J-U; Wiswedel, I; Hirsch, D; Gollnick, H P M

    2004-01-01

    UV irradiation of the human skin leads to induction of oxidative stress and inflammation mediated by reactive oxygen radicals, lipid peroxidation, liberation of arachidonic acid from membrane phospholipids and formation of prostaglandins and leucotrienes. We investigated "lipid mediators", such as F(2)-isoprostanes (8-iso-PGF(2alpha), 9alpha,11alpha-PGF(2alpha)) and monohydroxyeicosatetraenoic acids (HETEs) in the dermal interstitial fluid obtained by a cutaneous microdialysis technique. Defined areas on the volar forearm of 10 healthy volunteers were exposed to UVB irradiation (20-60 mJ/cm(2)). Microdialysis membranes were cutaneously inserted beneath the irradiated area. The probes were perfused with isotonic saline solution, and microdialysate samples were collected at 20-min intervals up to 4-5 h. Oxidized arachidonic acid derivatives (2-, 3-, 5-, 8-12- and 15-HETEs, 8-iso-PGF(2alpha) and 9alpha,11alpha-PGF(2alpha)) could be detected and quantified in microdialysates of normal skin in the picomole (HETEs) and femtomole (isoprostanes) range and after UVB irradiation using sensitive gas chromatography-mass spectrometry/negative ion chemical ionization. UVB irradiation enhanced the levels of 8-iso-PGF(2alpha) after 24 h significantly, whereas the HETE levels were slightly increased within shorter time intervals (3 h after UVB irradiation). Further investigations have to show whether these new findings are relevant to validate therapeutic strategies for topical and systemic UV prevention agents or for monitoring of specific therapeutic strategies in inflammatory skin disorders. PMID:14755126

  16. Failure of RNA synthesis to recover after UV irradiation: an early defect in cells from individuals with Cockayne's syndrome and xeroderma pigmentosum

    Previous work has shown that in cells from the ultraviolet-sensitive genetic disorder, Cockayne's syndrome, DNA synthesis fails to recover after ultraviolet irradiation, despite the fact that these cells have no detectable defect in either excision or daughter-strand repair pathways. We now show that Cockayne cells, as well as cells from a number of patients with xeroderma pigmentosum, are sensitive to the lethal effects of UV irradiation in stationary phase under conditions in which no DNA is synthesized after irradiation. Furthermore, in normal and defective human fibroblasts, RNA synthesis is depressed after UV irradiation. In normal (dividing) cells, RNA synthesis recovers very rapidly, but this recovery does not occur in Cockayne cells, and it is reduced or absent in xeroderma pigmentosum cells from different complementation groups. Qualitatively, similar results are obtained with cells in stationary phase. The recovery of RNA synthesis in the various defective cell strains is not correlated with the overall extent of excision repair, but there is some correlation between recovery of RNA synthesis and cell survival after ultraviolet irradiation. These results implicate recovery of RNA synthesis as an important early response to ultraviolet irradiation

  17. Synthesis, characterization and photocatalytic activity of WO3/TiO2 for NO removal under UV and visible light irradiation

    Samples with different proportions WO3/TiO2 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 N2 isotherms (BET). The photocatalytic properties of WO3/TiO2 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 WO3/TiO2 sample with a composition of 80% mole of TiO2. 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: • WO3/TiO2 prepared in simple way show high photocatalytic activity for NO removal. • The concrete was the best substrate to the performance of WO3/TiO2 with UV radiation. • The glass was the best substrate to the performance of WO3/TiO2 with visible radiation

  18. The influence of the UV irradiation intensity on photocatalytic activity of ZnAl layered double hydroxides and derived mixed oxides

    Hadnađev-Kostić Milica S.

    2012-01-01

    Full Text Available Layered double hydroxides (LDHs have been studied to a great extent as environmental-friendly complex materials that can be used as photocatalysts or photocatalyst supports. ZnAl layered double hydroxides and their derived mixed oxides were chosen for the investigation of photocatalytic performances in correlation with the UV intensities measured in the South Pannonia region. Low supersaturation coprecipitation method was used for the ZnAl LDH synthesis. For the characterization of LDH and thermal treated samples powder X-ray diffraction (XRD, scanning electron microscopy (SEM, electron dispersive spectroscopy (EDS, nitrogen adsorption-desorption were used. The decomposition of azodye, methylene blue was chosen as photocatalytic test reaction. The study showed that the ZnAl mixed oxide obtained by thermal decomposition of ZnAl LDH has stable activity in the broader UV light irradiation range characterizing the selected region. Photocatalytic activity could be mainly attributed to the ZnO phase, detected both in LDH and thermally treated samples. The study showed that the ZnAl mixed oxide obtained by the calcination of ZnAl LDH has a stable activity within the measured UV light irradiation range; whereas the parent ZnAl LDH catalyst did not perform satisfactory when low UV irradiation intensity is implied.

  19. The Stability of C-phycocyanin Doped Silica Biomaterials in UV Irradiation

    LI Ye; YANG Hui; CAO Fangming; ZHAO Xiaodong; WANG Jing

    2009-01-01

    The synthesized C-phycocyanins(C-PCs)doped silica biomaterials were charac-terized by the SEM and BET surface area analysis measurement.The morphology of C-PCs doped silica biomaterials indicates that the surface of the silica cluster is formed by a great number of silica particles with an average size of between 30 and 40 nm.Silica itself is a porous structure with the av-erage pore diameter of 2.95 nm.Pores with their diameter less than 5 nm account for 84.07%.In ad-dition,the C-PCs can be utilized as a fluorescent protein probe to monitor influence of the protein encapsulation and to study matrix and protein interaction and stability of protein in silica matrix.Ap-plication of protein encapsulation silica materials requires biomolecules to keep bioactivity and sta-bility on potentially unfavorable industrial conditions.The C-PCs in solution or in silicate matrix ir-radiated by ultraviolet ray can result in photobleaching,whereas the protein in the silica is less affected.The measured photodamage rate constant of C-PCs in buffer solution is 25 times faster than that of C-PCs in silica matrix.However,the lifetime of C-PCs in silica matrix or phosphate buffer is unaf-fected.These studies suggest that entrapment of C-PCs into silica matrixes not only can maintain their biological activity but also noticeably improve their photostability.

  20. Interaction of NO2 with TiO2 surface under UV irradiation: measurements of the uptake coefficient

    Y. Bedjanian

    2012-01-01

    Full Text Available The interaction of NO2 with TiO2 solid films was studied under UV irradiation using a low pressure flow reactor (1–10 Torr combined with a modulated molecular beam mass spectrometer for monitoring of the gaseous species involved. The NO2 to TiO2 reactive uptake coefficient was measured from the kinetics of NO2 loss on TiO2 coated Pyrex rods as a function of NO2 concentration, irradiance intensity (JNO2 = 0.002–0.012 s−1, relative humidity (RH = 0.06–69 %, temperature (T = 275–320 K and partial pressure of oxygen (0.001–3 Torr. TiO2 surface deactivation upon exposure to NO2 was observed. The initial uptake coefficient of NO2 on illuminated TiO2 surface (with 90 ppb of NO2 and JNO2≅0.006 s−1 was found to be γ0 = (1.2±0.4 ×10−4 (calculated using BET surface area under dry conditions at T = 300 K. The steady state uptake, γ, was several tens of times lower than the initial one, independent of relative humidity, and was found to decrease in the presence of molecular oxygen. In addition, it was shown that γ is not linearly dependent on the photon flux and seems to level off under atmospheric conditions. Finally, the following expression for γ was derived, γ = 2.3×10−3 exp(−1910/T/(1 + P0.36 (where P is O2 pressure in Torr, and recommended for atmospheric applications (for any RH, near 90 ppb of NO2 and JNO2 = 0.006 s−1.