WorldWideScience

Sample records for artificial ultraviolet radiation

  1. Risk from exposure to natural and artificial ultraviolet radiation

    International Nuclear Information System (INIS)

    The association between exposure to ultraviolet (UV) and damage to the skin and eyes is today generally accepted. Exposure to UV radiation may occur in several ways. Apart from the sun, there is a wide range of artificial sources used in different fields of industry, research and medicine, the exposure to which adds to the total exposure of an individual during his life-span. The potential effects of ozone layer depletion on the increase of the solar UV radiation at earth's surface, and therefor on human health, have recently been emphasized. Moreover, great attention has been devoted to the often uncontrolled use of UV lamps for tanning. This report shows the basis on which short and long term UV risk is assessed, and indicates some parameters necessary to its evaluation. The UV effects, both at molecular and cellular levels and on humans, are described together with their respective action spectra. The most common UV sources are then analyzed and their use in different fields is shown. Finally, some methods in dosimetry, which are useful for the correct measurement of exposure values, are described

  2. Ultraviolet radiation

    International Nuclear Information System (INIS)

    Ultraviolet radiation (UVR) from the sun or artificial sources is reflected or transmitted at the surface of the skin, about 5% of normally incident rays being directly reflected. The transmitted fraction is scattered, photochemically absorbed or dissipated as heat within the skin, or passes from it to contribute to the variable total amount of reflected and transmitted radiation. The UVR absorbers in skin are not definitely known, but DNA is a definite target and probably lipoprotein membranes, RNA, proteins, mucopolysaccharides, elastin and collagen. Photochemical or free radical damage to absorber or nearby organelles leads to pharmacological, ultrastructural, histological and clinical changes. Most frequent DNA damage is pyrimidine dimer formation, apparently inhibiting cell function and replication. This is largely enzymatically repaired in man in the dark by excision repair, post-replication repair and possible other enzymatic mechanisms, and at least in some organisms by light-induced photoreactivation repair. UVR exposure causes well recognized acute and chronic clinical syndromes in man. These are discussed in this paper

  3. Psoriasis and ultraviolet radiation

    International Nuclear Information System (INIS)

    Prevention and detection screening programs as a public health service in curtailing the ever-increasing incidence of all forms of skin cancer are reviewed. The effect of solar and artificial ultraviolet radiation on the general population and persons with psoriasis is examined. 54 refs

  4. Antioxidant responses of damiana (Turnera diffusa Willd to exposure to artificial ultraviolet (UV radiation in an in vitro model: part II; UV-B radiation

    Directory of Open Access Journals (Sweden)

    Lluvia de Abril Alexandra Soriano-Melgar

    2014-05-01

    Full Text Available Introduction: Ultraviolet type B (UV-B radiation effects on medicinal plants have been recently investigated in the context of climate change, but the modifications generated by UV-B radiation might be used to increase the content of antioxidants, including phenolic compounds. Objective: To generate information on the effect of exposure to artificial UV-B radiation at different high-doses in the antioxidant content of damiana plants in an in vitro model. Methods: Damiana plantlets (tissue cultures in Murashige-Skoog medium were irradiated with artificial UV-B at 3 different doses (1 0.5 ± 0.1 mW cm-2 (high for 2 h daily, (2 1 ± 0,1 mW cm-2 (severe for 2 h daily, or (3 1 ± 0.1 mW cm-2 for 4 h daily during 3 weeks. The concentration of photosynthetic pigments (chlorophylls a and b, carotenoids, vitamins (C and E and total phenolic compounds, the enzymatic activity of superoxide dismutase (SOD, EC 1.15.1.1 and total peroxidases (POX, EC 1.11.1, as well as total antioxidant capacity and lipid peroxidation levels were quantified to assess the effect of high artificial UV-B radiation in the antioxidant content of in vitro damiana plants. Results: Severe and high doses of artificial UV-B radiation modified the antioxidant content by increasing the content of vitamin C and decreased the phenolic compound content, as well as modified the oxidative damage of damiana plants in an in vitro model. Conclusion: UV-B radiation modified the antioxidant content in damiana plants in an in vitro model, depending on the intensity and duration of the exposure.

  5. Ultraviolet radiation and immunosuppression.

    LENUS (Irish Health Repository)

    Murphy, G M

    2009-11-01

    Ultraviolet (UV) radiation is a complete carcinogen. The effects of UV radiation are mediated via direct damage to cellular DNA in the skin and suppression of image surveillance mechanisms. In the context of organ transplantation, addiction of drugs which suppress the immune system add greatly to the carcinogenicity of UV radiation. This review considers the mechanisms of such effects.

  6. Antioxidant responses of damiana (Turnera diffusa Willd to exposure to artificial ultraviolet (UV radiation in an in vitro model: part I; UV-C radiation

    Directory of Open Access Journals (Sweden)

    Lluvia de Abril Alexandra Soriano-Melgar

    2014-05-01

    Full Text Available Introduction: Ultraviolet type C (UV-C radiation has higher energy than the UV-B radiation and has been less studied because it is completely absorbed by the ozone layer. However, artificial UV-C radiation can generate diverse modifications in the plants. Given that exposure to UV-C for short periods of time increases the antioxidant content, improving the appearance and shelf-life of products, its potential application in postharvest treatments to modify the antioxidant content of medicinal plants, such as damiana (Turnera diffusa, is novel and relevant. Objective: To determine the effects of UV-C radiation on enzymatic and non-enzymatic antioxidant defenses, as well as oxidative damage levels, in damiana (Turnera diffusa plants in vitro. Results: UV-C radiation decreased superoxide dismutase (SOD, EC 1.15.1.1 and total peroxidases (POX, EC 1.11.1 activities, the concentration of chlorophylls (a and b, carotenes, vitamin C, and total antioxidant capacity. UV-C radiation increased the phenolic compound levels in damiana. Loss of antioxidant defenses was higher in damiana plants exposed to higher UV-C doses and/or for longer periods. This study suggests that UV-C radiation induces oxidative stress, evidenced as increased protein carbonyls and phenolic compound content, in damiana (T. diffusa. Conclusion: Low dose, short exposure to UV-C stimulates phenolic compound content in damiana. Thus, controlled UV-C treatments could be used as postharvest treatment to increase phenolic compound content in damiana plants.

  7. Risk from exposure to natural and artificial ultraviolet radiation; Il rischio di esposizione alla radiazione ultravioletta naturale e artificiale

    Energy Technology Data Exchange (ETDEWEB)

    Matzeu, M. [Istituto Superiore di Sanita`, Rome (Italy). Lab. di Fisica

    1998-12-31

    The association between exposure to ultraviolet (UV) and damage to the skin and eyes is today generally accepted. Exposure to UV radiation may occur in several ways. Apart from the sun, there is a wide range of artificial sources used in different fields of industry, research and medicine, the exposure to which adds to the total exposure of an individual during his life-span. The potential effects of ozone layer depletion on the increase of the solar UV radiation at earth`s surface, and therefor on human health, have recently been emphasized. Moreover, great attention has been devoted to the often uncontrolled use of UV lamps for tanning. This report shows the basis on which short and long term UV risk is assessed, and indicates some parameters necessary to its evaluation. The UV effects, both at molecular and cellular levels and on humans, are described together with their respective action spectra. The most common UV sources are then analyzed and their use in different fields is shown. Finally, some methods in dosimetry, which are useful for the correct measurement of exposure values, are described. [Italiano] E` oggi generalmente accettata l`assciazione tra l`esposizione alla radiazione UV e alcuni danni alla pelle e agli occhi (carcinomi e cataratta). Le occasioni di esposizione sono molteplici; oltre al sole, anche una grande varieta` di sorgenti artificiali impiegate per scopi diversi nell`industria, nella ricerca e in medicina danno un contributo, non sempre valutabile, all`esposizione totale di un individuo nell`arco della sua vita. Recentemente e` stato posto l`accento sulle possibili conseguenze della riduzione dello stato di ozono stratosferico sull`aumento della frazione di UV solare al suolo e quindi sulla salute umana; particolare attenzione ha inoltre suscitato l`uso, spesso incontrollato, delle lampade UV per scopi estetici. Sono illustrate le basi sulle quali viene riconosciuto il rischio a breve e a lungo termine e sono definiti i parametri

  8. Ultraviolet radiation, sun and tanning salons

    CERN Document Server

    1999-01-01

    The pamphlet gives some information about ultraviolet radiation (UV), UV-sources and health effects, tanning in artificial and natural sun. It also includes some sun protection advice. It is intended mainly for persons inspecting artificial tanning units and for the owners of tanning salons. (Author)

  9. Ultraviolet radiation and health

    International Nuclear Information System (INIS)

    Ultraviolet radiation is a well-known carcinogen that has a large impact on biological structures and as a consequence on human health. While they have some positive effects associated with exposure to ultraviolet radiation, over exposures can lead to acute and chronic health effects on skin, eyes and immune system. With the right preventable measures, the negative effects associated with exposure to ultraviolet radiation can be largely avoided. The principal goal of preventive efforts is to reduce exposure to ultraviolet radiation through behavioral and environmental changes. While the mutagenic and carcinogenic properties of UV A are well established, mechanisms of UV A mutagenesis remain a matter of debate. However, the role of UV A in solar photo carcinogenesis appears more prominent that it was thought before. The most recent results have shown that mechanisms of photo carcinogenesis induced either by UV A or UV B are identical, their weight in the solar radiation being equivalent. Preventive efforts should be directed toward children and toward outdoor workers. Practical guides are provided by W.H.O. to assist local authorities to implement policies, practices and environmental changes that will reduce the risks associated with ultraviolet radiation. (author)

  10. Ultraviolet radiation watch in Portugal

    International Nuclear Information System (INIS)

    Ultraviolet radiation monitoring in Portugal started in the eighties using a broadband type detector installed at Lisbon. Currently, the Portuguese Institute of Meteorology has set up a new ultraviolet network using both spectral and broadband detectors covering most of the mainland territory and Madeira islands. Ultraviolet monitoring is complemented by the ultraviolet Index forecasting program started in 1999. A brief historical view, methodology and some results of the ultraviolet watch in Portugal are shown. (author)

  11. Natural and artificial ultraviolet radiation and skin cancer risk: what's new? Proceedings of the SFRP Non-ionizing radiation section round table

    International Nuclear Information System (INIS)

    The Non-ionizing radiation section of the French Society of Radiation Protection (SFRP) organized a technical meeting on the current knowledge of UV mutagenicity mechanisms, on professional exposures and on the risks linked with artificial tanning and their prevention. This document brings together the 3 available presentations (slides) of the talks given at the meeting: 1 - UV induction of DNA photoproducts: recent data (Thierry DOUKI, CEA Grenoble); 2 - Professional exposure to UV radiations (Mathieu BONIOL, IPRI); 3 - Artificial tanning: a major but avoidable public health problem (Jean-Francois DORE, Centre de Recherche en Cancerologie)

  12. Human exposure to ultraviolet radiation.

    Science.gov (United States)

    Diffey, B L

    1990-03-01

    Although the sun remains the main source of ultraviolet radiation (UVR) exposure in humans, the advent of artificial UVR sources has increased the opportunity for both intentional and unintentional exposure. Intentional exposure is most often to tan the skin. People living in less sunny climates can now maintain a year-round tan by using sunbeds and solaria emitting principally UVA radiation. Another reason for intentional exposure to artificial UVR is treatment of skin diseases, notably psoriasis. Unintentional exposure is normally the result of occupation. Outdoor workers, such as farmers, receive three to four times the annual solar UV exposure of indoor workers. Workers in many industries, eg, photoprinting or hospital phototherapy departments, may be exposed to UVR from artificial sources. One group particularly at risk is electric arc welders, where inadvertent exposure is so common that the terms "arc eye" or "welders flash" are often used to describe photokeratitis. In addition to unavoidable exposure to natural UVR, the general public is exposed to low levels of UVR from sources such as fluorescent lamps used for indoor lighting and shops and restaurants where UVA lamps are often used in traps to attract flying insects. PMID:2203439

  13. Ultraviolet radiation in Finland

    Energy Technology Data Exchange (ETDEWEB)

    Taalas, P.; Koskela, T.; Damski, J.; Supperi, A. [Finnish Meteorological Inst., Helsinki (Finland). Section of Ozone and UV Research; Kyroe, E. [Finnish Meteorological Inst., Sodankylae (Finland). Sodankylae Observatory

    1996-12-31

    Solar ultraviolet radiation is damaging for living organisms due to its high energy pro each photon. The UV radiation is often separated into three regions according to the wavelength: UVC (200-280 nm), UVB (280-320 nm) and UVA (320-400 nm). The most hazardous part, UVC is absorbed completely in the upper atmosphere by molecular oxygen. UVB radiation is absorbed by atmospheric ozone partly, and it is reaching Earth`s surface, as UVA radiation. Besides atmospheric ozone, very important factors in determining the intensity of UVB radiation globally are the solar zenith angle and cloudiness. It may be calculated from global ozone changes that the clear-sky UVB doses may have enhanced by 10-15 % during spring and 5-10 % during summer at the latitudes of Finland, following the decrease of total ozone between 1979-90. The Finnish ozone and UV monitoring activities have become a part of international activities, especially the EU Environment and Climate Programme`s research projects. The main national level effort has been the Finnish Academy`s climatic change programme, SILMU 1990-95. This presentation summarises the scientific results reached during the SILMU project

  14. Systematic for assessment of occupational exposure to ultraviolet radiation

    International Nuclear Information System (INIS)

    The approval of Royal Decree 486/2010 of 23 April on the protection of health and safety of workers from risks related to exposure to artificial optical radiation, moves to state law a framework of protection against the radiation. This should involve a significant intensification of control at work is conducted in this radiation. Despite the complexity of the issue and limit values ??difficult to apply (for incoherent ultraviolet radiation enters the bounding box up to 5 different values ??may apply), requires a systematic analysis of the problem well done. In this paper we consider the ultraviolet radiation generated by artificial sources.

  15. Effective ultraviolet irradiance measurements from artificial tanning devices in Greece.

    Science.gov (United States)

    Petri, Aspasia; Karabetsos, Efthymios

    2015-12-01

    Artificial tanning remains very popular worldwide, despite the International Agency for Research on Cancer classification of ultraviolet (UV) radiation from sunbeds as 'carcinogenic to humans'. Greek Atomic Energy Commission has initiated a surveillance action of the artificial tanning devices in Greece in order to record the effective irradiance levels from the sunbeds and to inform and synchronise the domestic artificial tanning business sector with the requirements of the European Standard EN 60335-2-27:2010. In this direction, in situ measurements of UV emissions from sunbeds in solaria businesses all over Greece were performed from October 2013 until July 2014, with a radiometer and a portable single-monochromator spectrophotometer. Analysis of the measurements' results revealed that effective irradiance in ∼60 % of the measured sunbeds exceeded the 0.3 W m(-2) limit value set by EN 60335-2-27:2010 and only 20 % of the devices could be categorised as UV type 3. PMID:25468991

  16. Unintentional exposure to ultraviolet radiation

    International Nuclear Information System (INIS)

    To evaluate the risks from unintentional exposure to ultraviolet radiation (UVR), and to consider hazard control regulation, one must face first the problem of their state of scientific knowledge and the public's perception of UVR. Few people in the general public would question the health benefits of sunlight. Many flock to the beaches each summer to develop a healthy tan. Since the 1920's scientists have recognized that most of the benefits--and risks--of sunlight exposure result from the UVR present in sunlight. Dermatologists warn sunbathers to avoid exposure or protect themselves against the intense midday UVR or risk skin cancer. A growing number of scientists warn of hazards to the eye if UVR--perhaps even shorter visible wavelengths--are not filtered by lenses. In addition to any intentional exposure for health or cosmetic purposes, many people are also exposed to UVR without being aware of it or without their intent to be exposed. Outdoor workers are exposed to sunlight, many industrial workers (e.g., welders) are exposed to UVR from arc sources, some UVR penetrates clothing, and people indoors are exposed to UVR from artificial lighting

  17. Ultraviolet radiation and skin cancer.

    Science.gov (United States)

    Narayanan, Deevya L; Saladi, Rao N; Fox, Joshua L

    2010-09-01

    Skin cancer is the most common type of cancer in fair-skinned populations in many parts of the world. The incidence, morbidity and mortality rates of skin cancers are increasing and, therefore, pose a significant public health concern. Ultraviolet radiation (UVR) is the major etiologic agent in the development of skin cancers. UVR causes DNA damage and genetic mutations, which subsequently lead to skin cancer. A clearer understanding of UVR is crucial in the prevention of skin cancer. This article reviews UVR, its damaging effects on the skin and its relationship to UV immunosuppression and skin cancer. Several factors influence the amount of UVR reaching the earth's surface, including ozone depletion, UV light elevation, latitude, altitude, and weather conditions. The current treatment modalities utilizing UVR (i.e. phototherapy) can also predispose to skin cancers. Unnecessary exposure to the sun and artificial UVR (tanning lamps) are important personal attributable risks. This article aims to provide a comprehensive overview of skin cancer with an emphasis on carefully evaluated statistics, the epidemiology of UVR-induced skin cancers, incidence rates, risk factors, and preventative behaviors & strategies, including personal behavioral modifications and public educational initiatives. PMID:20883261

  18. Ultraviolet-radiation-curable paints

    Energy Technology Data Exchange (ETDEWEB)

    Grosset, A M; Su, W F.A.; Vanderglas, E

    1981-09-30

    In product finishing lines, ultraviolet radiation curing of paints on prefabricated structures could be more energy efficient than curing by natural gas fired ovens, and could eliminate solvent emission. Diffuse ultraviolet light can cure paints on three dimensional metal parts. In the uv curing process, the spectral output of radiation sources must complement the absorption spectra of pigments and photoactive agents. Photosensitive compounds, such as thioxanthones, can photoinitiate unsaturated resins, such as acrylated polyurethanes, by a free radical mechanism. Newly developed cationic photoinitiators, such as sulfonium or iodonium salts (the so-called onium salts) of complex metal halide anions, can be used in polymerization of epoxy paints by ultraviolet light radiation. One-coat enamels, topcoats, and primers have been developed which can be photoinitiated to produce hard, adherent films. This process has been tested in a laboratory scale unit by spray coating these materials on three-dimensional objects and passing them through a tunnel containing uv lamps.

  19. Effective ultraviolet irradiance measurements from artificial tanning devices in Greece

    International Nuclear Information System (INIS)

    Artificial tanning remains very popular worldwide, despite the International Agency for Research on Cancer classification of ultraviolet (UV) radiation from sun-beds as 'carcinogenic to humans'. Greek Atomic Energy Commission has initiated a surveillance action of the artificial tanning devices in Greece in order to record the effective irradiance levels from the sun-beds and to inform and synchronise the domestic artificial tanning business sector with the requirements of the European Standard EN 60335-2-27:2010. In this direction, in situ measurements of UV emissions from sun-beds in solaria businesses all over Greece were performed from October 2013 until July 2014, with a radiometer and a portable single-monochromator spectrophotometer. Analysis of the measurements' results revealed that effective irradiance in ∼60 % of the measured sun-beds exceeded the 0.3 W m-2 limit value set by EN 60335-2-27:2010 and only 20 % of the devices could be categorised as UV type 3. (authors)

  20. Stomatal closure by ultraviolet radiation

    International Nuclear Information System (INIS)

    The effect of ultraviolet radiation (UV) (255–325 nm) on stomatal closure was investigated on tef [Eragrostis tef (Zucc) Trotter] in the presence of white light (ca 50 ·mol m−2 s−1). The action spectrum showed that UV (ca 2 ·mol m−2 s−1, half band width about 10 nm) of 285 nm or shorter wavelengths was very efficient in causing stomatal closure. The effectiveness decreased sharply towards longer wavelengths. Radiation of 313 nm or longer wavelengths was practically without effect. Increasing UV intensity increased stomatal resistance. When stronger white light (5 to 9 times stronger than the one used during irradiation) was administered, stomates re-opened rapidly irrespective of whether the UV was on or off, although a subsequent gradual closing tendency was observed when the UV was on. (author)

  1. Artificial suntanning: spectral irradiance and hazard evaluation of ultraviolet sources.

    Science.gov (United States)

    Gies, H P; Roy, C R; Elliott, G

    1986-06-01

    High incidences of skin damage and skin cancer amongst Australians have resulted in numerous campaigns to encourage people to protect themselves against solar ultraviolet radiation (UVR). The detrimental effects of UV-B radiation have been known for some time but recently there has been concern over the effects of UV-A radiation which had been thought of as relatively harmless. The proliferation of solaria, which incorporate UV-A sources, prompted the issuing of an Australian standard dealing with technical and non-technical aspects of the artificial suntanning industry. The purpose of this study was to measure the irradiance and spectral distribution of the emission from sunbeds and other UVR sources used for tanning, to evaluate the hazard potential and also the compliance with the standard. It was found that the majority of the UV-A lamps evaluated met the requirements of the standard. The UV-B lamps and portable sunlamps are potentially hazardous and their use should be discouraged. In general, the survey of solaria highlighted the need for further education of the public and especially the users and operators of solaria, on the hazards of UVR and of protective measures required for its safe use. PMID:3710779

  2. Additive effects of ultraviolet radiation

    International Nuclear Information System (INIS)

    A xenon-mercury high pressure lamp and a double monochromator were used to produce ultraviolet (uv) radiation at 295 nm. Pigmented rabbit eyes were irradiated and evaluated by slitlamp biomicroscopy. Corneal threshold (Hc) was 0.05 J.cm-2 and lens threshold (hL) was 0.75 J.cm-2. Other eyes were irradiated with 2 Hc and evaluated from 4 to 24 h at 4 h intervals. Corneal damage was only greater than that expected from a single Hc exposure if the separation between the two Hc exposures did not exceed 8 h. The most repeatable and reliable corneal response to these levels of uv was the development of corneal epithelial granules

  3. Photodetector of ultra-violet radiation

    International Nuclear Information System (INIS)

    The invention relates to photodetectors on the semiconductors base, in particular, to photodetectors of ultra-violet radiation and can be used in the optoelectronics systems for determining the intensity and dose of ultraviolet radiation emitted by the Sun and other sources. In the structure of the photodetector of ultraviolet radiation with a superficial potential barrier formed of semiconductors A3B5 with the prohibited power width Eg1, solid solutions thereof with the prohibited power width Eg2 and SnO2 or ITO, in the semiconductors A3B5 at a surface distance less than the absorption length of the visible radiation it is formed an isotype heterojunction between the semiconductors A3B5 and solid solutions thereof with the prohibited power width Eg2 > Eg1. The technical result consists in manufacturing of a photodetector sensitive solely to the ultraviolet radiation

  4. Impact of ultraviolet radiation on humans

    International Nuclear Information System (INIS)

    Solar radiation, including its ultraviolet (UV) components is a key factor in life on Earth. While small quantities of UV are beneficial for people (for example, through the production of vitamin D), the considerable amount to which people sometimes expose themselves may have extremely noxious effects including actinic erythema, sunburn, photo-induced diseases, photo-worsened diseases, actinic ageing and skin cancers. Since the last century, human exposure to UV has increased either by social-behaviour modifications, or by anthropogenic disruption to the environment through, among other things, industrial development. The World Health Organisation's (WHO) INTERSUN programme has several components: action for reconstruction of the ozone layer through, for example, preventing dumping of chlorofluorocarbons; creation and popularisation of a global UV index; prevention campaigns underlining the risks from UV exposure including dissemination of information to daily newspapers. These are all aimed at reducing the amount of UV radiation that people receive. In addition the WHO advises against exposure to UV artificial sources to reduce overall the quantity of UV received. (author)

  5. Some aspects of vacuum ultraviolet radiation physics

    CERN Document Server

    Damany, Nicole; Vodar, Boris

    2013-01-01

    Some Aspects of Vacuum Ultraviolet Radiation Physics presents some data on the state of research in vacuum ultraviolet radiation in association with areas of physics. Organized into four parts, this book begins by elucidating the optical properties of solids in the vacuum ultraviolet region (v.u.v.), particularly the specific methods of determination of optical constants in v.u.v., the properties of metals, and those of ionic insulators. Part II deals with molecular spectroscopy, with emphasis on the spectra of diatomic and simple polyatomic molecules, paraffins, and condensed phases. Part III

  6. Solar ultraviolet radiation in a changing climate

    Science.gov (United States)

    The projected large increases in damaging ultraviolet radiation as a result of global emissions of ozone-depleting substances have been forestalled by the success of the Montreal Protocol. New challenges are now arising in relation to climate change. We highlight the complex inte...

  7. Ultraviolet radiation therapy and UVR dose models

    Energy Technology Data Exchange (ETDEWEB)

    Grimes, David Robert, E-mail: davidrobert.grimes@oncology.ox.ac.uk [School of Physical Sciences, Dublin City University, Glasnevin, Dublin 9, Ireland and Cancer Research UK/MRC Oxford Institute for Radiation Oncology, Gray Laboratory, University of Oxford, Old Road Campus Research Building, Oxford OX3 7DQ (United Kingdom)

    2015-01-15

    Ultraviolet radiation (UVR) has been an effective treatment for a number of chronic skin disorders, and its ability to alleviate these conditions has been well documented. Although nonionizing, exposure to ultraviolet (UV) radiation is still damaging to deoxyribonucleic acid integrity, and has a number of unpleasant side effects ranging from erythema (sunburn) to carcinogenesis. As the conditions treated with this therapy tend to be chronic, exposures are repeated and can be high, increasing the lifetime probability of an adverse event or mutagenic effect. Despite the potential detrimental effects, quantitative ultraviolet dosimetry for phototherapy is an underdeveloped area and better dosimetry would allow clinicians to maximize biological effect whilst minimizing the repercussions of overexposure. This review gives a history and insight into the current state of UVR phototherapy, including an overview of biological effects of UVR, a discussion of UVR production, illness treated by this modality, cabin design and the clinical implementation of phototherapy, as well as clinical dose estimation techniques. Several dose models for ultraviolet phototherapy are also examined, and the need for an accurate computational dose estimation method in ultraviolet phototherapy is discussed.

  8. Sensitivity of winter phytoplankton communities from Andean lakes to artificial ultraviolet-B radiation Sensibilidad de comunidades fitoplanctónicas invernales de lagos andinos a la radiación ultravioleta-B artificial

    Directory of Open Access Journals (Sweden)

    E. WALTER HELBLING

    2001-06-01

    Full Text Available During July of 1999 sampling was carried out in five Andean lakes to determine the sensitivity of winter phytoplankton communities to ultraviolet-B radiation (UV-B, 280-320 nm. The studied lakes, Moreno, El Trébol, Nahuel Huapi, Gutiérrez, and Morenito, located in the Patagonia region (41° S, 71° W, 800 m of altitude, had attenuation coefficients for UV-B that ranged from 0.36 m-1 (Lake Moreno to 2.8 m-1 (Lake Morenito. The samples were inoculated with labeled carbon (NaH14CO3 and incubated in an illuminated chamber (UV-B = 0.35 W m-2, UV-A [320-400 nm] = 1.1 W m-2, and PAR [400-700 nm] = 10.8 W m-2 at 10 °C. The phytoplankton cells were exposed to UV radiation (280-400 nm + PAR (quartz tubes, and to UV-A + PAR (quartz tubes covered with Mylar-D. The total duration of the experiments was 4 h and two samples were taken from each treatment every hour. In lakes Moreno, El Trébol, Nahuel Huapi and Gutiérrez, the photosynthetic inhibition increased linearly with UV-B doses, while in Lake Morenito just a slight relationship was observed. After receiving a dose of 1.25 kJ m-2 (UV-B, phytoplankton from Lake Morenito had the highest cumulative photosynthetic inhibition (44 %, whereas in Lakes Moreno, El Trébol, Nahuel Huapi and Gutiérrez the inhibition was of 22, 11, 5, and 1 %, respectively. However, at the end of incubation period and after receiving doses of 5 kJ m-2, the most inhibited phytoplankton cells were from Lake Moreno (70 % and the most resistant (27 % was that from Lake Gutiérrez. The kinetics of inhibition was different in each lake, and transparent lakes, with higher proportion of large cells, had higher inhibition rates. The results suggest that an increase in UV-B radiation (e.g., produced by a decrease in stratospheric ozone would have a greater impact on microplankton from clear lakes, while pico- and nanoplankton from less transparent lakes will be less affectedDurante julio de 1999 se realizaron muestreos en cinco lagos

  9. Dosemeter for ultraviolet-radiation

    International Nuclear Information System (INIS)

    A commercial available, wrist watch like instrument for the measurement of UV-exposure by sun radiation will be described (SUNWATCH). The conditions will be indicated, under which this device can be used for the determination of the UV-exposure at workplace. (orig.)

  10. Ultraviolet Background Radiation from Cosmic Structure Formation

    OpenAIRE

    Miniati, Francesco; Ferrara, Andrea; White, Simon D. M.; Bianchi, Simone

    2003-01-01

    We calculate the contribution to the ultraviolet background (UVB) from thermal emission from gas shock heated by cosmic structure formation. Our main calculation is based on an updated version of Press-Schechter theory. It is consistent with a more empirical estimate based on the observed properties of galaxies and the observed cosmic star formation history. Thermal UVB emission is characterized by a hard spectrum extending well beyond 4 Ry. The bulk of the radiation is produced by objects in...

  11. Ultraviolet radiation cataract development and ascorbate supplementation

    OpenAIRE

    Mody, Vino C Jr

    2008-01-01

    Background: Cataract is the major cause of blindness in the world, and long-term solar ultraviolet radiation (UVR) is a major risk factor. The pathogenesis of UVRinduced cataract is studied in various animal models and cell systems. The significance of oxidation processes in cataract and other eye diseases has made the study of protective antioxidants increasingly important. Ascorbate, or vitamin C, is an important dietary antioxidant and essential nutrient in the human and ...

  12. Biological Sensors for Solar Ultraviolet Radiation

    OpenAIRE

    André P. Schuch; Teiti Yagura; Kazuo Makita; Hiromasa Yamamoto; Carlos F.M. Menck

    2011-01-01

    Solar ultraviolet (UV) radiation is widely known as a genotoxic environmental agent that affects Earth ecosystems and the human population. As a primary consequence of the stratospheric ozone layer depletion observed over the last decades, the increasing UV incidence levels have heightened the concern regarding deleterious consequences affecting both the biosphere and humans, thereby leading to an increase in scientific efforts to understand the role of sunlight in the induction of DNA damage...

  13. Diagnosis of TIG welding based on ultraviolet radiation

    Institute of Scientific and Technical Information of China (English)

    Li Zhiyong; Gu Xiaoyan; Wang Bao

    2009-01-01

    Through collecting the radiation of tungsten inert gas (TIG) welding arc, the radiation distribution in ultraviolet zone is analyzed in order to study the variation rule of ultraviolet radiation versus welding condition. The explanation for the variation is also provided bused on spectral radiation theory of arc light. Furthermore, through analysis of disturbanee factors, the integral intensity signal of radiation in ultraviolet zone is applied for diagnosis of welding process. The spectral signal of ultraviolet radiation can reflect the disturbance factors and welding conditions, which can be used for online diagnosis of welding process.

  14. Exposure of Finnish population to ultraviolet radiation and radiation measurements

    International Nuclear Information System (INIS)

    This report is based on a survey of the literature on radiation risks involved in sunbathing and the use of solaria. The purpose of the report is to provide background information for the development of regulations on solaria and for informing the public about the risks posed by solaria and the sun. The report gives an overview of the properties and biological effects of ultraviolet radiation. The most important regulations and recommendations issued in various countries are presented. The connection between ultraviolet radiation and the risks of skin cancer is examined both on a general level and in reference to information obtained from the Finnish Cancer Registry. In Finland, the incidence of melanomas nearly tripled between 1960 and 1980. The most important cause is considered to be the population's increased exposure to the su's ultraviolet radiation. There are no reliable data on the connection between the use of solaria and the risks of skin cancer. It is estimated, however, that solaria account for less than 10 per cent of the skin cancer risk of the whole population. There are some difficult physical problems associated with the measurement of ultraviolet radiation emitted by both natural sources and solaria. A preliminary study of these problems has been undertaken by means of a survey of the available literature, supplemented by a review of measurements performed by the Finnish Centre For Radiation and Nuclear Safety. The estimated inaccuracy of the Optronic 742 spectroradiometer used by the Centre in the measurement of ultraviolet radiation emitted by the sun and solaria is about +-14%

  15. Safety study on ultra-violet radiation

    International Nuclear Information System (INIS)

    Ultra-violet radiation (UVR) falls under category of non-ionising radiation (NIR). Excessive exposure to ultra-violet radiation (UVR) may cause significant health hazard to human beings. The sun is the main source of UVR which produce the radiation in the form of solar radiation. Due to its ability to cause hazard, a study of UV solar radiation exposure was conducted around Bangi, Selangor. For this preliminary study, selected measurement location were around Universiti Kebangsaan Malaysia (UKM) and MINT. The study was carried out by direct measurement of the radiation quantitatively with due consideration given on variation of time, cloud and weather condition. Research radiometer model IL 1700 with three different sensors were used for measurement of UV-A, UV-B and UV-C and they were connected to Laptop with LabView software for data analysis. The results were compared with the permissible exposure limits recommended by IRPA/ICNIRP. In addition to assessment of direct exposure to UVR the study also look into the effectiveness of absorption for some material such as tinted glass and different kind of clothing. The results showed that UV-A, UV-B and UV-C emitted directly from the sun around UKM and MINT were below the permissible limit recommended by IRPA/ICNIRP for members of public (30 J/m2 or 1mWm-2). Besides that, they study found that tinted glass was effective to protect us from excessive exposure to UVR . For clothing we found that the silk fabric with light colour is more applicable for filtering UV radiation, compare to the other type of fabric. (Author)

  16. SUMER: Solar Ultraviolet Measurements of Emitted Radiation

    Science.gov (United States)

    Wilhelm, K.; Axford, W. I.; Curdt, W.; Gabriel, A. H.; Grewing, M.; Huber, M. C. E.; Jordan, S. D.; Kuehne, M.; Lemaire, P.; Marsch, E.

    1992-01-01

    The experiment Solar Ultraviolet Measurements of Emitted Radiation (SUMER) is designed for the investigations of plasma flow characteristics, turbulence and wave motions, plasma densities and temperatures, structures and events associated with solar magnetic activity in the chromosphere, the transition zone and the corona. Specifically, SUMER will measure profiles and intensities of Extreme Ultraviolet (EUV) lines emitted in the solar atmosphere ranging from the upper chromosphere to the lower corona; determine line broadenings, spectral positions and Doppler shifts with high accuracy, provide stigmatic images of selected areas of the Sun in the EUV with high spatial, temporal and spectral resolution and obtain full images of the Sun and the inner corona in selectable EUV lines, corresponding to a temperature from 10,000 to more than 1,800,000 K.

  17. The measurement of solar ultraviolet radiation.

    Science.gov (United States)

    Roy, C R; Gies, H P; Lugg, D J; Toomey, S; Tomlinson, D W

    1998-11-01

    High skin cancer rates, stratospheric ozone depletion and increased public interest and concern have resulted in a strong demand for solar ultraviolet radiation measurements and information. The Australian Radiation Laboratory (ARL) has been involved since the mid-1980s in the measurement of solar ultraviolet radiation (UVR) using spectroradiometers (SRM) and a network of broadband detectors at 18 sites in Australia and Antarctica and in Singapore through a collaborative agreement with the Singapore Institute of Science and Forensic Medicine. Measurement locations range from equatorial (Singapore, 1.3 degrees N) through tropical (Darwin, 12.4 degrees S) to polar (Mawson, 67.6 degrees S) and as a result there are many difficulties associated with maintenance and calibration of the network detectors, and transfer of data to ensure an accurate and reliable data collection. Calibration procedures for the various detectors involve the comparison with simultaneous spectral measurements using a portable SRM incorporating a double monochromator, calibrated against traceable standard lamps. Laboratory measurements of cosine response and responsivity are also made. Detectors are intercompared at the Yallambie site for a number of months before installation at another location. As an additional check on the calibrations, computer models of solar UVR at the earth's surface for days with clear sky and known ozone are compared with the UV radiometer measurements. PMID:9920423

  18. Ultraviolet radiation, vitamin D and multiple sclerosis.

    Science.gov (United States)

    Lucas, Robyn M; Byrne, Scott N; Correale, Jorge; Ilschner, Susanne; Hart, Prue H

    2015-10-01

    There is compelling epidemiological evidence that the risk of developing multiple sclerosis is increased in association with low levels of sun exposure, possibly because this is associated with low vitamin D status. Recent work highlights both vitamin D and non-vitamin D effects on cellular immunity that suggests that higher levels of sun exposure and/or vitamin D status are beneficial for both MS risk and in ameliorating disease progression. Here we review this recent evidence, focusing on regulatory cells, dendritic cells, and chemokines and cytokines released from the skin following exposure to ultraviolet radiation. PMID:26477548

  19. Cosmic far-ultraviolet background radiation

    International Nuclear Information System (INIS)

    It is demonstrated that interstellar dust grains forward-scatter far-ultraviolet radiation extremely strongly: the value of the Henyey-Greenstein scattering parameter g at 1425 A is shown to be at least 0.75; the actual value is very likely greater than 0.9. Also, observations of the Virgo cluster of galaxies sets a limit tau > 2 x 1025 sec on the life-time of 17-20 eV/c2 heavy neutrinos, if such neutrinos are responsible for the gravitational binding of the cluster. (Auth.)

  20. Toxic effects of ultraviolet radiation on the skin

    International Nuclear Information System (INIS)

    Ultraviolet (UV) irradiation present in sunlight is an environmental human carcinogen. The toxic effects of UV from natural sunlight and therapeutic artificial lamps are a major concern for human health. The major acute effects of UV irradiation on normal human skin comprise sunburn inflammation (erythema), tanning, and local or systemic immunosuppression. At the molecular level, UV irradiation causes DNA damage such as cyclobutane pyrimidine dimers and (6-4) photoproducts, which are usually repaired by nucleotide excision repair (NER). Chronic exposure to UV irradiation leads to photoaging, immunosuppression, and ultimately photocarcinogenesis. Photocarcinogenesis involves the accumulation of genetic changes, as well as immune system modulation, and ultimately leads to the development of skin cancers. In the clinic, artificial lamps emitting UVB (280-320 nm) and UVA (320-400 nm) radiation in combination with chemical drugs are used in the therapy of many skin diseases including psoriasis and vitiligo. Although such therapy is beneficial, it is accompanied with undesirable side effects. Thus, UV radiation is like two sides of the same coin--on one side, it has detrimental effects, and on the other side, it has beneficial effects

  1. Maps of ultraviolet radiation in Costa Rica

    International Nuclear Information System (INIS)

    Ultraviolet radiation (UV) has contributed relatively little energy to the solar spectrum; but is important, because it is biologically active. The software Surfer 8 has created maps designed of the territory of Costa Rica to assess the maximum levels of solar UV radiation on a horizontal plane. The data were used in creating the maps, were predicted at local noon in eighty-three locations scattered across the country, with a spectral atmospheric model which is physically established. The model has used as input data: the date and time, the location identified by latitude, longitude and height of land above sea level, the value of the vertical column ozone, surface albedo and atmospheric turbidity parameters. The estimate differs by 3% of the measurements made in situ, which agrees with the experimental data. The model has used the data estimation of UV radiation, clear sky conditions, which is the condition where you get the maximum energy possible in each locality. This is of fundamental importance when assessing the adverse effects on human health, leads the maximum intensity in this important solar spectrum band. A larger increase of 23% has presented in the UV radiation with altitude obtaining the hills and mountains the highest rates and places located at sea level and the lowest cost, the indices. The annual variation analysis has revealed an increase greater than 27% from the month of lowest UV radiation (December) and the month of greatest UV radiation (April). The issue is of particular interest because of the increasing number of people moving at different times of the year, altitudes over 2000 m altitude, in activities relating to tourism and employment. These individuals are significant increases in levels of UV solar radiation under conditions of clear skies. (author)

  2. Coral skeletons defend against ultraviolet radiation.

    Directory of Open Access Journals (Sweden)

    Ruth Reef

    Full Text Available BACKGROUND: Many coral reef organisms are photosynthetic or have evolved in tight symbiosis with photosynthetic symbionts. As such, the tissues of reef organisms are often exposed to intense solar radiation in clear tropical waters and have adapted to trap and harness photosynthetically active radiation (PAR. High levels of ultraviolet radiation (UVR associated with sunlight, however, represent a potential problem in terms of tissue damage. METHODOLOGY/PRINCIPAL FINDINGS: By measuring UVR and PAR reflectance from intact and ground bare coral skeletons we show that the property of calcium carbonate skeletons to absorb downwelling UVR to a significant extent, while reflecting PAR back to the overlying tissue, has biological advantages. We placed cnidarians on top of bare skeletons and a UVR reflective substrate and showed that under ambient UVR levels, UVR transmitted through the tissues of cnidarians placed on top of bare skeletons were four times lower compared to their counterparts placed on a UVR reflective white substrate. In accordance with the lower levels of UVR measured in cnidarians on top of coral skeletons, a similar drop in UVR damage to their DNA was detected. The skeletons emitted absorbed UVR as yellow fluorescence, which allows for safe dissipation of the otherwise harmful radiation. CONCLUSIONS/SIGNIFICANCE: Our study presents a novel defensive role for coral skeletons and reveals that the strong UVR absorbance by the skeleton can contribute to the ability of corals, and potentially other calcifiers, to thrive under UVR levels that are detrimental to most marine life.

  3. Solar radiation and the ultraviolet radiation exposure standard

    International Nuclear Information System (INIS)

    Partly as a result of increased concern over the possible depletion of stratospheric ozone and concomitant biological effects such as an increased incidence of skin cancer, ARL is extending the scope of its solar ultraviolet radiation (UVR) measurement programme. The results obtained thus far will be presented and their implication for the outdoor worker will be discussed in terms of the Australian occupational UVR exposure standard and the need to change existing work practises and personal protection

  4. Some resistance mechanisms to ultraviolet radiation

    International Nuclear Information System (INIS)

    The cyclical exposure of bacterial cells to the ultraviolet light (UV) it has as consequence an increment in the resistance to the lethal effects of this type of radiation, increment that happens as a result of a selection process of favorable genetic mutations induced by the same UV light. With object to study the reproducibility of the genetic changes and the associate mechanisms to the resistance to UV in the bacteria Escherichia coli, was irradiated cyclically with UV light five different derived cultures of a single clone, being obtained five stumps with different resistance grades. The genetic mapping Hfr revealed that so much the mutation events like of selection that took place during the adaptation to the UV irradiation, happened of random manner, that is to say, each one of the resistant stumps it is the result of the unspecified selection of mutations arisen at random in different genes related with the repair and duplication of the DNA. (Author)

  5. Disruption of cytoplasmic microtubules by ultraviolet radiation

    International Nuclear Information System (INIS)

    Ultraviolet (UV) irradiation of cultured human skin fibroblasts causes the disassembly of their microtubules. Using indirect immunofluorescence microscopy, we have now investigated whether damage to the microtubule precursor pool may contribute to the disruption of microtubules. Exposure to polychromatic UV radiation inhibits the reassembly of microtubules during cellular recovery from cold treatment. In addition, the ability of taxol to promote microtubule polymerization and bundling is inhibited in UV-irradiated cells. However, UV irradiation of taxol-pretreated cells or in situ detergent-extracted microtubules fails to disrupt the microtubule network. These data suggest that damage to dimeric tubulin, or another soluble factor(s) required for polymerization, contributes to the disassembly of microtubules in UV-irradiated human skin fibroblasts

  6. SUMER: Solar Ultraviolet Measurements of Emitted Radiation

    Science.gov (United States)

    Wilhelm, K.; Axford, W. I.; Curdt, W.; Gabriel, A. H.; Grewing, M.; Huber, M. C. E.; Jordan, M. C. E.; Lemaire, P.; Marsch, E.; Poland, A. I.

    1988-01-01

    The SUMER (solar ultraviolet measurements of emitted radiation) experiment is described. It will study flows, turbulent motions, waves, temperatures and densities of the plasma in the upper atmosphere of the Sun. Structures and events associated with solar magnetic activity will be observed on various spatial and temporal scales. This will contribute to the understanding of coronal heating processes and the solar wind expansion. The instrument will take images of the Sun in EUV (extreme ultra violet) light with high resolution in space, wavelength and time. The spatial resolution and spectral resolving power of the instrument are described. Spectral shifts can be determined with subpixel accuracy. The wavelength range extends from 500 to 1600 angstroms. The integration time can be as short as one second. Line profiles, shifts and broadenings are studied. Ratios of temperature and density sensitive EUV emission lines are established.

  7. Ultraviolet radiation and plants: burning questions

    International Nuclear Information System (INIS)

    Plants use sunlight for photosynthesis and, as a consequence, are exposed to the ultraviolet (UV) radiation that is present in sunlight. UV radiation is generally divided into three classes: UV-C, UV-6, and UV-A. The UV-C region of the UV spectrum includes wavelengths below 280 nm; these highly energetic wavelengths are effectively absorbed by ozone in the stratosphere and, thus, are not present in sunlight at the earth’s surface. UV-C wavelengths will be removed from the light reaching the earth’s surface’so long as there is any ozone present (Caldwell et al., 1989). In contrast, UV radiation in the UV-B region, from 280 to 320 nm, does reach ground level. The UV-B portion of sunlight has received much attention in recent years because irradiation from this spectral region (especially 297 to 310 nm) will increase as the stratospheric ozone concentration decreases (Caldwell et al., 1989). Currently, ozone decreases result from chlorofluorocarbon contamination of the stratosphere (McFarland and Kaye, 1992). UV wavelengths from 320 to 390 nm, which make up the UV-A region of the spectrum, are not attenuated by ozone, so their fluence will be unaffected by ozone layer reduction. Like all living organisms, plants sense and respond to UV radiation, both the wavelengths present in sunlight (UV-A and UV-B) and the wavelengths below 280 nm (UV-C). AI1 types of UV radiation are known to damage various plant processes. Such damage can be classified into two categories: damage to DNA (which can cause heritable mutations) and damage to physiological processes. There has been much speculation about how increased UV radiation exposure will affect plants, but as yet, there are no definitive answers. In this review, I will discuss the kinds of damage that UV radiation can inflict on plants, the mechanisms plants use to perceive and respond to UV radiation, and the ecological relevance of UV light wavelengths that have been used in the experimental analysis of plant responses

  8. Stratospheric ozone, ultraviolet radiation and climate change; Ozone stratospherique, rayonnement ultraviolet et changement climatique

    Energy Technology Data Exchange (ETDEWEB)

    Boucher, O. [Met Office Hadley Centre (United Kingdom)

    2008-11-15

    It is well known that an overexposure to ultraviolet radiation is associated with a number of health risks such as an increased risk of cataracts and skin cancers. At a time when climate change is often blamed for all our environmental problems, what is the latest news about the stratospheric ozone layer and other factors controlling ultraviolet radiation at the surface of the Earth? Will the expected changes in the chemical composition of the atmosphere and changes in our climate increase or decrease the risk for skin cancer? This article investigates the role of the various factors influencing ultraviolet radiation and presents the latest knowledge on the subject. (author)

  9. Biological Sensors for Solar Ultraviolet Radiation

    Directory of Open Access Journals (Sweden)

    André P. Schuch

    2011-04-01

    Full Text Available Solar ultraviolet (UV radiation is widely known as a genotoxic environmental agent that affects Earth ecosystems and the human population. As a primary consequence of the stratospheric ozone layer depletion observed over the last decades, the increasing UV incidence levels have heightened the concern regarding deleterious consequences affecting both the biosphere and humans, thereby leading to an increase in scientific efforts to understand the role of sunlight in the induction of DNA damage, mutagenesis, and cell death. In fact, the various UV-wavelengths evoke characteristic biological impacts that greatly depend on light absorption of biomolecules, especially DNA, in living organisms, thereby justifying the increasing importance of developing biological sensors for monitoring the harmful impact of solar UV radiation under various environmental conditions. In this review, several types of biosensors proposed for laboratory and field application, that measure the biological effects of the UV component of sunlight, are described. Basically, the applicability of sensors based on DNA, bacteria or even mammalian cells are presented and compared. Data are also presented showing that on using DNA-based sensors, the various types of damage produced differ when this molecule is exposed in either an aqueous buffer or a dry solution. Apart from the data thus generated, the development of novel biosensors could help in evaluating the biological effects of sunlight on the environment. They also emerge as alternative tools for using live animals in the search for protective sunscreen products.

  10. Exposure to ultraviolet radiation: recommendations for cosmetic use

    International Nuclear Information System (INIS)

    The beginning of the so-called tanning industry made possible the acquisition of a tanned skin independently of the available solar radiation. The tan is produced by ultraviolet radiation and, as well as in solar exposure, there are additional risks on the use of the so-called sun-beds. The damaging effects of ultraviolet exposure are well documented and reasonably quantified. The objective of this paper is to inform the potential effects of ultraviolet radiation exposure in sun-beds and to provide recommendations in order to reduce the associated risks. These recommendations are adapted for cosmetics use only (author)

  11. ULTRAVIOLET PROTECTIVE PIGMENTS AND DNA DIMER INDUCTION AS RESPONSES TO ULTRAVIOLET RADIATION

    Science.gov (United States)

    Life on Earth has evolved adaptations to many environmental stresses over the epochs. One consistent stress has been exposure to ultraviolet (UV) radiation. The most basic effect of UV radiation on biological systems is damage to DNA. In response to UV radiation organisms have ad...

  12. Ultraviolet Background Radiation from Cosmic Structure Formation

    CERN Document Server

    Miniati, F; White, S D M; Bianchi, S; Miniati, Francesco; Ferrara, Andrea; White, Simon D. M.; Bianchi, Simone

    2004-01-01

    We calculate the contribution to the ultraviolet background (UVB) from thermal emission from gas shock heated by cosmic structure formation. Our main calculation is based on an updated version of Press-Schechter theory. It is consistent with a more empirical estimate based on the observed properties of galaxies and the observed cosmic star formation history. Thermal UVB emission is characterized by a hard spectrum extending well beyond 4 Ry. The bulk of the radiation is produced by objects in the mass range 10^11-13 M_solar, i.e. large galaxies and small groups. We compute a composite UVB spectrum due to QSO, stellar and thermal components. The ratio of the UVB intensities at the H and He Lyman limits increases from 60 at z=2 to more than 300 at z=6. A comparison of the resulting photoionization rates to the observed Gunn-Peterson effect at high redshifts constrains the escape fraction of ionizing photons from galaxies to be less than a few percent. Near 1 Ry, thermal and stellar emission are comparable amoun...

  13. Ultraviolet Radiation Exposure Criteria (invited paper)

    International Nuclear Information System (INIS)

    During the past 25 years occupational health and safety guidelines, regulations and standards have evolved to protect workers and the general public from potentially hazardous exposure to ultraviolet radiation. A further goal has been to promote the safe design and use of suntanning devices, optical instruments, lamps, and laser products. From the gradually expanding knowledge of the biological effects of UVR exposure of the eye and skin, exposure limits have been slightly revised over the past two decades - by both national and international organisations. The general trend has been a convergence of differing limits. The greatest divergence in guidelines and standards has occurred where the biological effects are least understood or are simply controversial. Philosophical differences in the level of protection have played a role, since there are those who argue that UVR exposure offers more benefit than is accepted by all. The earliest guidelines were limited to UVR from low-pressure mercury lamps used in germicidal applications in the 1940s. By 1972 a North-American guideline based upon an envelope action spectrum had appeared. The International Non-Ionizing Radiation Committee (INIRC) of the International Radiation Protection Association (IRPA) proposed similar guidelines in 1985 and these were revised based upon newer data a few years later. After an extensive review of the IRPA/INIRC guidelines, the International Commission on Non-Ionizing Radiation Protection revalidated and endorsed those limits. Although these guidelines were based firstly on preventing any acute effects, they have also been analysed to show that the risk is extremely small, or undetectable, for delayed effects for persons exposed below these recommended limits. The limits are approximately one-third of an MED (for fair skin) in any eight-hour period. At this level, detectable molecular damage appears to be fully repaired. Further refinement is still called for. For example, the maximal

  14. Comment on "Swarming Ring Patterns in Bacterial Colonies Exposed to Ultraviolet Radiation"

    CERN Document Server

    Ordemann, A; Ordemann, Anke; Moss, Frank

    2002-01-01

    Commenting on the paper "Swarming Ring Patterns in Bacterial Colonies Exposed to Ultraviolet Radiation" of A.M. Delprato et al., Phys. Rev. Lett 87, 158102 (2001) we point out that their observed ring pattern formation by colonies of soil bacteria Bacillus subtilis exposed to ultra violet (UV) radiation might be caused by the artificial confinement of motile bacteria evolved to live in a 3-dimensional environment to a 2-dimensional geometry. We propose that to investigate the reaction of Bacillus subtilis to UV radiation coming from above, a seminal experiment should have a 3-dimensional setup.

  15. PBS Nanodots for Ultraviolet Radiation Nanosensor

    Science.gov (United States)

    Dekhtyar, Yu.; Romanova, M.; Anischenko, A.; Sudnikovich, A.; Polyaka, N.; Reisfeld, R.; Saraidarov, T.; Polyakov, B.

    PbS nanodots embedded in a zirconium oxide nanofilm were explored as possible ultraviolet (UV) sensors for nanodosimetry purposes. The nanodots were excited by ultraviolet photons to get emission of weak electrons. The emitted charge correlated to UV exposure indicates that PbS nanodots have potential for use as UV sensors for nanodosimetry.

  16. Systematic for assessment of occupational exposure to ultraviolet radiation; Sistematica para la valoracion de la exposicion laboral frente a radiaciones ultravioletas

    Energy Technology Data Exchange (ETDEWEB)

    Anies Escartin, J.; Perramon Llado, A.

    2011-07-01

    The approval of Royal Decree 486/2010 of 23 April on the protection of health and safety of workers from risks related to exposure to artificial optical radiation, moves to state law a framework of protection against the radiation. This should involve a significant intensification of control at work is conducted in this radiation. Despite the complexity of the issue and limit values ??difficult to apply (for incoherent ultraviolet radiation enters the bounding box up to 5 different values ??may apply), requires a systematic analysis of the problem well done. In this paper we consider the ultraviolet radiation generated by artificial sources.

  17. Ultraviolet background radiation from cosmic structure formation

    Science.gov (United States)

    Miniati, Francesco; Ferrara, Andrea; White, Simon D. M.; Bianchi, Simone

    2004-03-01

    We calculate the contribution to the ultraviolet background (UVB) from thermal emission from gas shock heated during cosmic structure formation. Our main calculation is based on an updated version of Press-Schechter theory. It is consistent with a more empirical estimate based on the observed properties of galaxies and the observed cosmic star formation history. Thermal UVB emission is characterized by a hard spectrum extending well beyond 4 Ryd. The bulk of the radiation is produced by objects in the mass range 1011-1013 Msolar, i.e. large galaxies and small groups. We compute a composite UVB spectrum due to quasi-stellar object (QSO), stellar and thermal components. The ratio of the UVB intensities at the H and He Lyman limits increases from 60 at z= 2 to more than 300 at z= 6. A comparison of the resulting photoionization rates to the observed Gunn-Peterson effect at high redshifts constrains the escape fraction of ionizing photons from galaxies to be less than a few per cent. Near 1 Ryd, thermal and stellar emission are comparable, amounting to about 10, 20 and 35 per cent of the total flux at redshifts of 3, 4.5 and higher, respectively. However, near the ionization threshold for He II, the thermal contribution is much stronger. It is comparable to the QSO intensity already at redshift ~3 and dominates at redshifts above 4. Thermal photons alone are enough to produce and sustain He II reionization already at z~ 6. We discuss the possible implications of our results for the thermal history of the intergalactic medium, in particular for He II reionization.

  18. Ultraviolet radiation and skin cancer of humans.

    Science.gov (United States)

    Urbach, F

    1997-08-01

    Current scientific evidence indicates that stratospheric ozone has declined worldwide over the past 20 years. The trend estimates are markedly dependent on the geographical location and are highly seasonal. Winter trends are much more negative than those for summer and autumn. Projections based on current assumptions of chlorine release suggest that this decline will continue into the next century. On the basis of the decrease in ozone over the mid-latitudes, an increase in biologically effective ultraviolet radiation (UVR) of 4%-9% is expected, depending on the season and geographical location. However, the UVR penetration to the Earth's surface is greatly affected by clouds, aerosols and tropospheric ozone, and current increases, if any, have not been as large as this. Direct evidence for the induction of non-melanoma skin cancer (NMSC) due to UVR has been derived from animal experiments in mice and rats. Numerous epidemiological data confirm that this relationship also holds for human skin. The increase in NMSC incidence in the past two decades is not likely to be due to the decrease in ozone, given the long latency (two to three decades) associated with UVR effects on skin. A knowledge of the action spectrum for NMSC development suggests that a 1% depletion in stratospheric ozone may be expected to increase NMSC, at equilibrium, by about 2.0% The evidence on the role of UVR exposure in the development of malignant melanoma (MM) is less certain. It has been estimated that a 1% reduction in ozone may cause an increase in MM of 0.6%. PMID:9301039

  19. Effects of ultraviolet radiation on mole rats kidney: A histopathologic and ultrastructural study

    Directory of Open Access Journals (Sweden)

    Hüseyin Türker

    2014-04-01

    Full Text Available The purpose of this study was to realize the ultrastructural effects of ultraviolet radiation on the kidney tissue cells of mole rats (Spalax leucodon. The mole rats of 180–200 g body weight were divided into the control and radiation-trial groups. The control group was not given any radiation. The other groups were irradiated with artificially produced UVC radiation for 14, 28 and 60 days. The kidney tissue samples were prepared at the end of experiments and analyzed by the light and electron microscope. Several effects were observed in the kidney tissues cells analyzed in accordance with the dose magnitude of radiation. These results clearly show the detrimental effects of UVC radiation on kidney tissue cells in exposure periods dependent on radiation dose and exposure time.

  20. Establishing a Ultraviolet Radiation Observational Network and Enhancing the Study on Ultraviolet Radiation

    Institute of Scientific and Technical Information of China (English)

    白建辉; 王庚辰

    2003-01-01

    On the basis of analyzing observational data on solar radiation, meteorological parameters, and totalozone amount for the period of January 1990 to December 1991 in the Beijing area, an empirical calculationmethod for ultraviolet radiation (UV) in clear sky is obtained. The results show that the calculated valuesagree well with the observed, with maximum relative bias of 6.2% and mean relative bias for 24 months of1.9%. Good results are also obtained when this method is applied in Guangzhou and Mohe districts. Thelong-term variation of UV radiation in clear sky over the Beijing area from 1979 to 1998 is calculated, andthe UV variation trends and causes are discussed: direct and indirect UV energy absorption by increasingpollutants in the troposphere may have caused the UV decrease in clear sky in the last 20 years. With theenhancement of people's quality of life and awareness of health, it will be valuable and practical to providUV forecasts for typical cities and rural areas. So, we should develop and enhance UV study in systematicmonitoring, forecasting, and developing a good and feasible method for UV radiation reporting in China,especially for big cities.

  1. Solar ultraviolet radiation as a trigger of cell signal transduction

    International Nuclear Information System (INIS)

    Ultraviolet light radiation in sunlight is known to cause major alterations in growth and differentiation patterns of exposed human tissues. The specific effects depend on the wavelengths and doses of the light, and the nature of the exposed tissue. Both growth inhibition and proliferation are observed, as well as inflammation and immune suppression. Whereas in the clinical setting, these responses may be beneficial, for example, in the treatment of psoriasis and atopic dermatitis, as an environmental toxicant, ultraviolet light can induce significant tissue damage. Thus, in the eye, ultraviolet light causes cataracts, while in the skin, it induces premature aging and the development of cancer. Although ultraviolet light can damage many tissue components including membrane phospholipids, proteins, and nucleic acids, it is now recognized that many of its cellular effects are due to alterations in growth factor- and cytokine-mediated signal transduction pathways leading to aberrant gene expression. It is generally thought that reactive oxygen intermediates are mediators of some of the damage induced by ultraviolet light. Generated when ultraviolet light is absorbed by endogenous photosensitizers in the presence of molecular oxygen, reactive oxygen intermediates and their metabolites induce damage by reacting with cellular electrophiles, some of which can directly initiate cell signaling processes. In an additional layer of complexity, ultraviolet light-damaged nucleic acids initiate signaling during the activation of repair processes. Thus, mechanisms by which solar ultraviolet radiation triggers cell signal transduction are multifactorial. The present review summarizes some of the mechanisms by which ultraviolet light alters signaling pathways as well as the genes important in the beneficial and toxic effects of ultraviolet light

  2. Ultraviolet Radiation Constraints around the Circumstellar Habitable Zones

    CERN Document Server

    Buccino, A P; Mauas, P J D; Buccino, Andrea P.; Lemarchand, Guillermo A.; Mauas, Pablo J. D.

    2005-01-01

    Ultraviolet radiation is known to inhibit photosynthesis, induce DNA destruction and cause damage to a wide variety of proteins and lipids. In particular, UV radiation between 200-300 nm becomes energetically very damaging to most of the terrestrial biological systems. On the other hand, UV radiation is usually considered one of the most important energy source on the primitive Earth for the synthesis of many biochemical compounds and, therefore, essential for several biogenesis processes. In this work, we use these properties of the UV radiation to define the bounderies of an ultraviolet habitable zone. We also analyze the evolution of the UV habitable zone during the main sequence stage of the star. We apply these criteria to study the UV habitable zone for those extrasolar planetary systems that were observed by the International Ultraviolet Explorer (IUE). We analyze the possibility that extrasolar planets and moons could be suitable for life, according to the UV constrains presented in this work and othe...

  3. Ultraviolet radiation response of two heterotropy Antarctic marine bacterial

    International Nuclear Information System (INIS)

    Two Antarctic marine bacterial strains, were exposed to different irradiance of ultraviolet (UV) solar radiation using several experimental protocols and interferential filters. Results showed that both, UV-A and UV-B radiation produce deleterious effects on two tested bacterial strains. The mortality values under UVB treatments were higher than those observed under UVA treatments. UVvi strain proved to be more resistant to UV radiation than the UVps strain. (author)

  4. Ultraviolet Radiation Constraints around the Circumstellar Habitable Zones

    OpenAIRE

    Buccino, Andrea P.; Lemarchand, Guillermo A.; Mauas, Pablo J. D.

    2005-01-01

    Ultraviolet radiation is known to inhibit photosynthesis, induce DNA destruction and cause damage to a wide variety of proteins and lipids. In particular, UV radiation between 200-300 nm becomes energetically very damaging to most of the terrestrial biological systems. On the other hand, UV radiation is usually considered one of the most important energy source on the primitive Earth for the synthesis of many biochemical compounds and, therefore, essential for several biogenesis processes. In...

  5. THE PRINCIPLES OF SANITARY AND EPIDEMIOLOGICAL RESTRICTIONS OF ARTIFICIAL ULTRAVIOLET RAYS EMANATION IN SUN PARLORS

    OpenAIRE

    Akymenko, V.Y.; Yarygin, A.V.; Khodakovskaya, V.A.; Avramenko, L.M.; Grygus, I.M.

    2013-01-01

    Annotation Was conducted analytical overview of existing principles regulating the usage of artificial ultraviolet emission in solariums in Russian Federation, Republic of Belarus, and also of the integrating recommendations of the WHO, in comparison with the results of our own research. This allows to define key directions of scientific-research activities in the sphere of evaluating the influence of this harmful factor on the organism of solariums visitors. Was proved the necessity of de...

  6. Nonionising radiation and risk of human cancer: comparison of ultraviolet and radiofrequency radiation

    International Nuclear Information System (INIS)

    Human exposure to ultraviolet radiation (UVR) comes largely from sunlight, although a small proportion of people receive high dose UVR from artificial sources. The causal link between solar UVR and the keratinocyte cancers, basal cell carcinomas and squamous cell carcinomas of the skin, is well-established based on a large body of observational and experimental evidence. UVR damages molecules such as DNA directly and this is the principal mechanism of carcinogenesis, though other mechanisms such as immunosuppression and interaction with viruses may also be involved. People are also exposed to another form of nonionising radiation, radiofrequency radiation (RFR), through occupation, the community environment from base stations, and through use of cellular telephones and related communications devices. However, unlike UVR, the relationship between RFR and cancer is far from clear. The main tumours that have been investigated to date are brain tumours and leukaemia but assessing the RFR exposure pathway to such cancers poses many methodological challenges for epidemiologists. Refinements to measurement of exposure are the major urgent need, and the lack of evidence regarding carcinogenic effects of RFR in experimental settings complicates the assessment. Further insights into the links between RFR and chronic disease such as cancer are likely in the next few years however when results of several large-scale epidemiological studies now in train around the world become available

  7. Polarized vacuum ultraviolet and X-radiation

    Science.gov (United States)

    Samson, J. A. R.

    1978-01-01

    The most intense source of polarized vacuum UV and X radiation is synchrotron radiation, which exhibits a degree of partially polarized light between about 80-100%. However, the radiation transmitted by vacuum UV monochromators can also be highly polarized. The Seya-Namioka type of monochromator can produce partially polarized radiation between 50-80%. For certain experiments it is necessary to know the degree of polarization of the radiation being used. Also, when synchrotron radiation and a monochromator are combined the polarization characteristic of both should be known in order to make full use of these polarization properties. The polarizing effect of monochromators (i.e., diffraction gratings) have been measured at the Seya angle and at grazing angles for various spectral orders. Experimental evidence is presented which shows that the reciprocity law holds for polarization by reflection where the angle of incidence and diffraction are unequal. These results are reviewed along with the techniques for measuring the degree of polarization.

  8. Experimental Determination of Ultraviolet Radiation Protection of Common Materials

    Science.gov (United States)

    Tavares, Susana C. A.; da Silva, Joaquim C. G. Esteves; Paiva, Joao

    2007-01-01

    Aiming at a better understanding of the problems associated with the depletion of the ozone layer, we propose several experiments to be performed by students of different levels: secondary and first-year undergraduate students. The oxidation of iodide induced by ultraviolet (UV) radiation, generated by a mercury lamp, is used as an indicator for…

  9. Potential of herbs in skin protection from ultraviolet radiation

    OpenAIRE

    Korać, Radava R.; Khambholja, Kapil M.

    2011-01-01

    Herbs have been used in medicines and cosmetics from centuries. Their potential to treat different skin diseases, to adorn and improve the skin appearance is well-known. As ultraviolet (UV) radiation can cause sunburns, wrinkles, lower immunity against infections, premature aging, and cancer, there is permanent need for protection from UV radiation and prevention from their side effects. Herbs and herbal preparations have a high potential due to their antioxidant activity, primarily. Antioxid...

  10. The Relationship between Ultraviolet Radiation Exposure and Vitamin D Status

    OpenAIRE

    Ola Engelsen

    2010-01-01

    This paper reviews the main factors influencing the synthesis of vitamin D, with particular focus on ultraviolet radiation exposure. On the global level, the main source of vitamin D is the sun. The effect of solar radiation on vitamin D synthesis depends to some extent on the initial vitamin D levels. At moderate to high latitudes, diet becomes an increasingly important source of vitamin D due to decreased solar intensity and cold temperatures, which discourage skin exposure. During the mid-...

  11. OSL response of Al2O3:C inlight dot detectors to ultraviolet radiation

    International Nuclear Information System (INIS)

    The commercial dosimeters Al2O3:C InLight Dot and the OSL microStar System reader, both developed by Landauer, were utilized in this work for the detection of ultraviolet radiation. The OSL response of Al2O3:C InLight Dots was obtained in relation to the parameters of irradiance and illumination time using an UV artificial source. The results showed an increase of the OSL response and a tendency to saturation about 1.7 W.m-2 of irradiance and 30 min of UV illumination. (author)

  12. Observed ozone response to variations in solar ultraviolet radiation

    Science.gov (United States)

    Gille, J. C.; Smythe, C. M.; Heath, D. F.

    1984-01-01

    During the winter of 1979, the solar ultraviolet irradiance varied with a period of 13.5 days and an amplitude of 1 percent. The zonal mean ozone values in the tropics varied with the solar irradiance, with an amplitude of 0.25 to 0.60 percent. This observation agrees with earlier calculations, although the response may be overestimated. These results imply changes in ozone at an altitude of 48 kilometers of up to 12 percent over an 11-year solar cycle. Interpretation of ozone changes in the upper stratosphere will require measurements of solar ultraviolet radiation at wavelengths near 200 nanometers.

  13. Key issues of ultraviolet radiation of OH at high altitudes

    International Nuclear Information System (INIS)

    Ultraviolet (UV) emissions radiated by hydroxyl (OH) is one of the fundamental elements in the prediction of radiation signature of high-altitude and high-speed vehicle. In this work, the OH A2Σ+→X2Π ultraviolet emission band behind the bow shock is computed under the experimental condition of the second bow-shock ultraviolet flight (BSUV-2). Four related key issues are discussed, namely, the source of hydrogen element in the high-altitude atmosphere, the formation mechanism of OH species, efficient computational algorithm of trace species in rarefied flows, and accurate calculation of OH emission spectra. Firstly, by analyzing the typical atmospheric model, the vertical distributions of the number densities of different species containing hydrogen element are given. According to the different dominating species containing hydrogen element, the atmosphere is divided into three zones, and the formation mechanism of OH species is analyzed in the different zones. The direct simulation Monte Carlo (DSMC) method and the Navier-Stokes equations are employed to compute the number densities of the different OH electronically and vibrationally excited states. Different to the previous work, the trace species separation (TSS) algorithm is applied twice in order to accurately calculate the densities of OH species and its excited states. Using a non-equilibrium radiation model, the OH ultraviolet emission spectra and intensity at different altitudes are computed, and good agreement is obtained with the flight measured data

  14. Ultraviolet Radiation in the Solar System

    CERN Document Server

    Vázquez, M

    2006-01-01

    UV radiation is an important part in the electromagnetic spectrum since the energy of the photons is great enough to produce important chemical reactions in the atmospheres of planets and satellites of our Solar System, thereby affecting the transmission of this radiation to the ground and its physical properties. Scientists have used different techniques (balloons and rockets) to access to the information contained in this radiation, but the pioneering of this new frontier has not been free of dangers. The Sun is our main source of UV radiation and its description occupies the first two chapters of the book. The Earth is the only known location where life exists in a planetary system and therefore where the interaction of living organism with UV radiation can be tested through different epochs and on distinct species. The development of the human technology has affected the natural shield of ozone that protects complex lifeforms against damaging UV irradiation. The formation of the ozone hole and its consequ...

  15. Swarming Ring Patterns in Bacterial Colonies Exposed to Ultraviolet Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Delprato, Anna M.; Samadani, Azadeh; Kudrolli, A.; Tsimring, L. S.

    2001-10-08

    We report a novel morphological transition in a Bacillus subtilis colony initially growing under ambient conditions, after ultraviolet radiation exposure. The bacteria in the central regions of the colonies are observed to migrate towards the colony edge forming a ring during uniform spatial exposure. When the radiation is switched off, the colonies were observed to grow both inward into the evacuated regions as well as outward indicating that the pattern is not formed due to depletion of nutrients at the center of the colony. We also propose a reaction-diffusion model in which waste-limited chemotaxis initiated by the UV radiation leads to the observed phenomenology.

  16. The Relationship between Ultraviolet Radiation Exposure and Vitamin D Status

    Directory of Open Access Journals (Sweden)

    Ola Engelsen

    2010-05-01

    Full Text Available This paper reviews the main factors influencing the synthesis of vitamin D, with particular focus on ultraviolet radiation exposure. On the global level, the main source of vitamin D is the sun. The effect of solar radiation on vitamin D synthesis depends to some extent on the initial vitamin D levels. At moderate to high latitudes, diet becomes an increasingly important source of vitamin D due to decreased solar intensity and cold temperatures, which discourage skin exposure. During the mid-winter season, these factors result in decreased solar radiation exposure, hindering extensively the synthesis of vitamin D in these populations.

  17. Plant response to solar ultraviolet radiation

    Science.gov (United States)

    Caldwell, M. M.

    1981-01-01

    Plant reactions and mechanisms of reaction to solar UV radiation are reviewed, along with characteristics of plants which enhance UV tolerance. Wavelength regions to which proteins are particularly sensitive are examined and the possibility of synergistic effects from photoreactions to multiple wavelengths is considered, along with available evidence of nonadditive plant spectral responses to UV radiation. Decreases in atmospheric ozone content are explored in terms of UV wavelengths which would increase with the ozone decreases, particularly for UV-B, which depresses photosynthesis and would increase 1% with a 16% reduction of stratospheric ozone. Higher elevations are projected to display effects of increased UV incident flux first, and global distributions of UV increases due to atmospheric inhomogeneity and water surface clarity are examined. Finally, the response of plant nucleic acids, DNA, chlorophyll to enhanced UV are described, along with repair, avoidance, and optical mechanisms which aid plant survival

  18. Genetics of human sensitivity to ultraviolet radiation

    Science.gov (United States)

    Cleaver, James E.

    1994-07-01

    the major human health effects of solar and artificial UV light occur from the UVB and UVC wavelength ranges and involve a variety of short-term and long-term deleterious changes to the skin and eyes. the more important initial damage to cellular macromolecules involves dimerization of adjacent pyrimidines in DNA to produce cyclobutane pyrimidine dimes, (6-4) pyrimidine- pyrimidone, and (6-4) dewar photoproducts. these photoproducts can be repaired by a genetically regulated enzyme system (nucleotide excision repair) which removes oligonucleotides 29-30 nucleotides long that contain the photoproducts, and synthesizes replacement patches. At least a dozen gene products are involved in the process of recognizing photoproducts in DNA, altering local DNA helicity and cleaving the polynucleotide chain at defined positions either side of a photoproduct. Hereditary mutations in many of these genes are recognized in the human genetic disorders xeroderma pigmentosum (XP), Cockayne syndrome (CS), and trichothiodystrophy (TTD). Several of the gene products have other functions involving the regulation of gene transcription which accounts for the complex clinical presentation of repair deficient diseases that involve sensitivity of the skin and eyes to UV light, increased solar carcinogenesis (in XP), demyelination, and ganglial calcification (in CS), hair abnormalities (in TTD), and developmental and neurological abnormalities

  19. Detection of ultraviolet radiation using tissue equivalent radiochromic gel materials

    International Nuclear Information System (INIS)

    Ferrous Xylenol-orange Gelatin gel (FXG) is known to be sensitive to ionising radiation such as γ and X-rays. The effect of ionising radiation is to produce an increase in the absorption over a wide region of the visible spectrum, which is proportional to the absorbed dose. This study demonstrates that FXG gel is sensitive to ultraviolet radiation and therefore it could functions as UV detector. Short exposure to UV radiation produces linear increase in absorption measured at 550nm, however high doses of UV cause the ion indicator colour to fad away in a manner proportional to the incident UV energy. Light absorbance increase at the rate of 1.1% per minute of irradiation was monitored. The exposure level at which the detector has linear response is comparable to the natural summer UV radiation. Evaluating the UV ability to pass through tissue equivalent gel materials shows that most of the UV gets absorbed in the first 5mm of the gel materials, which demonstrate the damaging effects of this radiation type on human skin and eyes. It was concluded that FXG gel dosimeter has the potential to offer a simple, passive ultraviolet radiation detector with sensitivity suitable to measure and visualises the natural sunlight UV exposure directly by watching the materials colour changes.

  20. Threat of ultraviolet radiation to the eye--how to protect against it

    International Nuclear Information System (INIS)

    The purpose of this paper is to discuss the effects of exposure of the eye to ultraviolet (UV) radiation and to provide information from which protective criteria and standards may be established. To accomplish this purpose, the article discusses ultraviolet radiation, absorption of UV radiation by the eye, the effects of ocular exposure to ultraviolet radiation, and how to protect the eye against exposure to UV radiation

  1. European Code against Cancer 4th Edition: Ultraviolet radiation and cancer.

    Science.gov (United States)

    Greinert, Rüdiger; de Vries, Esther; Erdmann, Friederike; Espina, Carolina; Auvinen, Anssi; Kesminiene, Ausrele; Schüz, Joachim

    2015-12-01

    Ultraviolet radiation (UVR) is part of the electromagnetic spectrum emitted naturally from the sun or from artificial sources such as tanning devices. Acute skin reactions induced by UVR exposure are erythema (skin reddening), or sunburn, and the acquisition of a suntan triggered by UVR-induced DNA damage. UVR exposure is the main cause of skin cancer, including cutaneous malignant melanoma, basal-cell carcinoma, and squamous-cell carcinoma. Skin cancer is the most common cancer in fair-skinned populations, and its incidence has increased steeply over recent decades. According to estimates for 2012, about 100,000 new cases of cutaneous melanoma and about 22,000 deaths from it occurred in Europe. The main mechanisms by which UVR causes cancer are well understood. Exposure during childhood appears to be particularly harmful. Exposure to UVR is a risk factor modifiable by individuals' behaviour. Excessive exposure from natural sources can be avoided by seeking shade when the sun is strongest, by wearing appropriate clothing, and by appropriately applying sunscreens if direct sunlight is unavoidable. Exposure from artificial sources can be completely avoided by not using sunbeds. Beneficial effects of sun or UVR exposure, such as for vitamin D production, can be fully achieved while still avoiding too much sun exposure and the use of sunbeds. Taking all the scientific evidence together, the recommendation of the 4th edition of the European Code Against Cancer for ultraviolet radiation is: "Avoid too much sun, especially for children. Use sun protection. Do not use sunbeds." PMID:26096748

  2. Stratospheric ozone fluctuation and ultraviolet radiation over Serbia

    OpenAIRE

    Nikolić Jugoslav L.; Ducić Vladan D.; Martić-Bursać Nataša M.

    2011-01-01

    Increased ultraviolet radiation potentially detrimental to health is a direct effect of the reduced ozone layer of the Earth’s atmosphere. Stratospheric ozone over the territory of Serbia and immediate surrounding depleted in the considered period of 1979-2008; its amount reduced by 7.6%. Solar and volcanic activities have significant effect on the interannual variability of the stratospheric ozone. Ozone layer over Serbia is 13.8% thicker than the planetary layer, with the ozone hole f...

  3. Pollen and spores as a passive monitor of ultraviolet radiation

    OpenAIRE

    WesleyTobyFraser; BarryHarveyLomax; PhillipEJardine; MarkASephton

    2014-01-01

    Sporopollenin is the primary component of the outer walls of pollen and spores. The chemical composition of sporopollenin is responsive to levels of ultraviolet (UV) radiation exposure, via a concomitant change in the concentration of phenolic compounds. This relationship offers the possibility of using fossil pollen and spore chemistry as a novel proxy for past UV flux. Phenolic compounds in sporopollenin can be quantified using Fourier Transform infrared spectroscopy. The high potential for...

  4. Strong far field coherent scattering of ultraviolet radiation by holococcolithophores

    CERN Document Server

    Quintero-Torres, R; Torres, M; Estrada, M; Cros, L

    2007-01-01

    By considering the structure of holococcoliths (calcite plates that cover holococcolithophores, a haploid phase of the coccolithophore life cycle) as a photonic structure, we apply a discrete dipolar approximation to study the light backscattering properties of these algae. We show that some holococcolith structures have the ability to scatter the ultraviolet (UV) radiation. This property may represent an advantage for holococcolithophores possessing it, by allowing them to live higher in the water column than other coccolithophores.

  5. Whales Use Distinct Strategies to Counteract Solar Ultraviolet Radiation

    OpenAIRE

    Martinez-Levasseur, Laura M.; Birch-Machin, Mark A; Amy Bowman; Diane Gendron; Elizabeth Weatherhead; Knell, Robert J.; Karina Acevedo-Whitehouse

    2013-01-01

    A current threat to the marine ecosystem is the high level of solar ultraviolet radiation (UV). Large whales have recently been shown to suffer sun-induced skin damage from continuous UV exposure. Genotoxic consequences of such exposure remain unknown for these long-lived marine species, as does their capacity to counteract UV-induced insults. We show that UV exposure induces mitochondrial DNA damage in the skin of seasonally sympatric fin, sperm, and blue whales and that this damage accumula...

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

    Science.gov (United States)

    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

  7. Degradation of glass fibre/polyester composites after ultraviolet radiation

    Energy Technology Data Exchange (ETDEWEB)

    Gu Huang [School of Textiles, Tianjin Polytechnic University, 63 Chenglin Road, Tianjin 300160 (China)], E-mail: huanglll@public.tpt.tj.cn

    2008-07-01

    Glass fabrics and unsaturated polyester resin were selected to fabricate 2, 3 and 5-layer laminates. After ultraviolet (UV) radiation for 20-200 h, laminates were subjected to tensile strength testing. For the 2-layer laminates, after 170-h UV lamp radiation, the tensile strength reduction of the materials became significant. Distinctive degradation was noticed after 200-h UV irradiation for the 3-layer specimens. No evident strength reduction was discovered for the 5-layer samples after 200-h treatment. It is concluded from the research that shot period of UV radiation has no significant influence on the material as far as tensile strength is concerned. Examinations of the fracture surface of the specimen under SEM revealed the deteriorated matrix after extended UV radiation.

  8. Ultraviolet Radiation in Overcast Sky at the Surface

    Institute of Scientific and Technical Information of China (English)

    自建辉; 王庚辰; 胡非

    2003-01-01

    Based on the analysis of one year of observation data of solar radiation at the ground in Beijing in 1990, a simple empirical formula for calculating UV radiation in overcast sky is established. The formula is Quv/Quv0 = A1S + A0, where Quv and Quvo are monthly mean daily sums of UV exposure in overcast sky and clear sky, respectively. S is the daily sunshine hours. The calculated results agree well with the observed. The maximum and minimum relative biases are 9.9% and 0.1%, respectively, and the yearly relative bias is 2.9%. The ratio of ultraviolet radiation of overcast sky to clear sky in 1990 is between 44.6% and 61.8%, and the yearly average is 53.9%. Thus, almost half of the UV energy is lost in the atmosphere in overcast sky in 1990.

  9. Ultraviolet radiation and health: from hazard identification to effective prevention.

    Science.gov (United States)

    Yamaguchi, N; Kinjo, Y; Akiba, S; Watanabe, S

    1999-12-01

    The increased exposure to ultraviolet (UV) radiation due to ozone depletion is one of the most serious global health problems. The UV exposure is known to cause skin carcinoma, cataract and deteriorated immune function, but for countries like Japan, the magnitude of health effects of UV radiation is yet to be elucidated. The International Workshop on the Health Effects of Ultraviolet Radiation was held in Tokyo, Japan, on February 17-19, 1999, in attempts to visualize the size of this problem and to identify better solutions. Through this workshop, several lines of scientific evidence were provided, which clearly show that the risk of cataract and skin cancer among people living in Japan increases with the increasing level of sun exposure. We must seek, therefore, the extent to which the UV exposure of given intensity causes adverse health effects in Japanese population. Through the workshop, the importance of preventive measure was confirmed. The scientific basis of prevention is, of course, the knowledge of dose-response relationship and the current exposure status in Japanese population. It is hoped that the communications between researchers in Japan and other countries are strengthened through this workshop. PMID:10709343

  10. The effects of ultraviolet radiation on some plastic detectors

    International Nuclear Information System (INIS)

    Exposure to ultraviolet (U.V.) radiation could lead to the development of phototoxicity, photoallergy and enhancement of photocarcinogenesis (IRPA 1979). For the measurement of the dose of ultraviolet radiation harmful to human bodies, it is desirable to use a detector with a response curve similar to the human action spectra for erythema and for ultraviolet radiation. It is not easy to obtain a detector which satisfies the requirement unless a very complicated setup of spectrometer with suitable photodetectors is employed. For the purpose of measuring the personal dose, a passive type of detector is preferred. Davis et al (1976) has developed a detector using polysulphone for this purpose. The response curve shows a broad peak extending from 260 to 325 nm. Other detectors (spectrosonics, Partridge and Barton 1978, Fanslow et al 1983), which were developed for similar purposes, have a sharp peak around 280 to 320 nm. These response curves are not very good approximations to the human action spectrum which has a sharp cut-off at around 300 nm. They tend to overestimate the contribution on the long wavelength region (300-320 nm) of UV-B. The integrated response in the UV-B region could be twice the total area of the human action spectrum in the same region of wavelength. The irradiance of these long wavelengths is at least ten times that of the short wavelengths (less than 300 nm) in the solar spectrum. A search for materials with a better approximation than the three types of detectors mentioned above would be useful in the development of a more accurate dosimeter. In this paper, we will report our preliminary results on a new type of plastic material

  11. Review of the use of ultraviolet radiation in crime detection in the UK

    International Nuclear Information System (INIS)

    Advances in technology are leading to an increase in the number of applications that use optical radiation sources in the UK. One example is the use of sources of ultraviolet (UV) radiation for the detection of index security marking solutions used in crime detection. EU Member States have until the 27 April 2010 to implement the requirements of the Physical Agents (Artificial Optical Radiation) Directive (2006/25/EC) into national law. The Health and Safety Executive (HSE) are leading UK Government action to develop implementing regulations, carry out impact assessments and consult with stakeholders in relation to this Directive. The aim of the project described in this paper was to examine the types of static equipment in use at police custody suites and the protective measures to control employees', and in particular examining officers, exposure to UV radiation. Visits made to a sample number of custody suites within UK police stations identified differences in the protective measures being implemented to control UV radiation exposure. The project was a qualitative review of equipment and use. Radiation emission measurements and exposure assessments were not undertaken. (author)

  12. Stratospheric ozone fluctuation and ultraviolet radiation over Serbia

    International Nuclear Information System (INIS)

    Increased ultraviolet radiation potentially detrimental to health is a direct effect of the reduced ozone layer of the Earth's atmosphere. Stratospheric ozone over the territory of Serbia and immediate surrounding depleted in the considered period of 1979-2008; its amount reduced by 7.6%. Solar and volcanic activities have significant effect on the interannual variability of the stratospheric ozone. Ozone layer over Serbia is 13.8% thicker than the planetary layer, with the ozone hole forming once in five years on average without serious health implications. (author)

  13. Nature of the Background Ultraviolet Radiation Field at High Redshifts

    Indian Academy of Sciences (India)

    Archana Samantaray; Pushpa Khare

    2000-06-01

    We have tried to determine the flux of the ultraviolet background radiation field from the column density ratios of various ions in several absorption systems observed in the spectra of QSOs. We find that in most cases the flux is considerably higher than what has been estimated to be contributed by the AGNs. The excess flux could originate locally in hot stars. In a few cases we have been able to show that such galactic flux can only contribute a part of the total required flux. The results suggest that the background gets a significant contribution from an unseen QSO population.

  14. Nano-antennae assisted emission of extreme ultraviolet radiation

    Energy Technology Data Exchange (ETDEWEB)

    Pfullmann, Nils; Noack, Monika; Cardoso de Andrade, Jose; Rausch, Stefan; Nagy, Tamas; Kovacev, Milutin [Leibniz Universitaet Hannover, Quantum Optics Institute (Germany); QUEST Centre for Quantum Engineering and Space-Time Research, Hannover (Germany); Reinhardt, Carsten [Laser Zentrum Hannover (Germany); Knittel, Vanessa; Bratschitsch, Rudolf; Leitenstorfer, Alfred [University of Konstanz, Department of Physics and Center for Applied Photonics (Germany); Akemeier, Dieter; Huetten, Andreas [Universitaet Bielefeld, AG Duenne Schichten Physik der Nanostrukturen (Germany); Morgner, Uwe [Leibniz Universitaet Hannover, Quantum Optics Institute (Germany); QUEST Centre for Quantum Engineering and Space-Time Research, Hannover (Germany); Laser Zentrum Hannover (Germany)

    2014-04-15

    High-order harmonic generation in xenon with oscillator repetition rates is studied. The necessary intensity is reached via plasmonic field enhancement at nanostructured arrays of bow-tie gold antennae. The theoretical analysis focuses on the thermal properties and the damage threshold of the bow-tie antennae. On the experimental side the number of contributing atoms is determined and optimized. Extreme ultraviolet radiation is successfully observed with photon fluxes almost an order of magnitude larger than previously reported. (copyright 2014 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Mutations induced by ultraviolet radiation affecting virulence in Puccinia striiformis

    International Nuclear Information System (INIS)

    Uredospores of parent culture, cy 29-1, were treated by ultraviolet radiation and mutations to virulent were tested on resistant wheat cultivars inoculated with treated spores. 7 mutant cultures virulent to the test cultivars were developed with estimated mutation rate 10~6~10~4. The virulence of mutant cultures was different from the all known races of stripe rust. Resistance segregation to mutant cultures was detected in two test cultivars. The results suggested that mutation was important mechanism of virulence variation operative in asexual population of rust fungi

  16. Ocular damage induced by near-ultraviolet laser radiation

    International Nuclear Information System (INIS)

    A quantitative study was conducted of ocular damage thresholds in the rhesus monkey eye from krypton, argon, and nitrogen laser radiation. Corneal and lenticular thresholds are reported for various laser beam parameters. Corneal damage was found to occur following incident energy doses of approximately 60 to 70 Joules per square centimeter (J./cm.2) for pulsewidths ranging from 250 μsec to 120 sec. The results are consistent with a photochemical damage mechanism. With certain exposure parameters, cataracts were induced with lower energy doses than required to cause corneal damage. The lenticular thresholds, however, appear to be consistent with a thermal rather than a photochemical mechanism. Corneal and lenticular hazards of near-ultraviolet (near-uv) lasers are discussed in terms of existing safety standards for laser radiation

  17. Diagnosis of clear sky ultraviolet radiation for Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Lemus Deschamps, L. [Bureau of Meteorology Research Centre (Australia); Galindo, I.; Solano, R.; Elizalde, A.T.; Fonseca, J. [Centro Universitario de Investigaciones en Ciencias del Ambiente, University of Colima (Mexico)

    2002-07-01

    A discrete-ordinate radiative transfer model is employed to develop a regional clear sky ultraviolet (UV) diagnosis system. The clear sky UV radiation, weighted by the spectral sensitivity of human skin is calculated using the Total Ozone Mapping Spectrometer (TOMS) data sets. Examples of the geographical clear sky UV Index distributions are presented and the model results are compared with surface UV measurements from University of Colima for 1999. [Spanish] Utilizando un modelo de transferencia de radiacion de ordenadas discretas se desarrolla un sistema para el diagnostico de la distribucion de radiacion ultravioleta para cielo despejado en la Republica Mexicana. La radiacion para cielo despejado se obtiene utilizando la respuesta espectral de la piel humana y los datos de satelite de ozono total registrados por el espectrometro TOMS. Se presentan ejemplos del Indice de radiacion ultravioleta (UV Index) calculados con el modelo y se comparan con las mediciones en superficie obtenidas en la Universidad de Colima durante 1999.

  18. Assessment and comparison of methods for solar ultraviolet radiation measurements

    International Nuclear Information System (INIS)

    In the study, the different methods to measure the solar ultraviolet radiation are compared. The methods included are spectroradiometric, erythemally weighted broadband and multi-channel measurements. The comparison of the different methods is based on a literature review and assessments of optical characteristics of the spectroradiometer Optronic 742 of the Finnish Centre for Radiation and Nuclear Safety (STUK) and of the erythemally weighted Robertson-Berger type broadband radiometers Solar Light models 500 and 501 of the Finnish Meteorological Institute and STUK. An introduction to the sources of error in solar UV measurements, to methods for radiometric characterization of UV radiometers together with methods for error reduction are presented. Reviews on experiences from world-wide UV monitoring efforts and instrumentation as well as on the results from international UV radiometer intercomparisons are also presented. (62 refs.)

  19. Assessment and comparison of methods for solar ultraviolet radiation measurements

    Energy Technology Data Exchange (ETDEWEB)

    Leszczynski, K.

    1995-06-01

    In the study, the different methods to measure the solar ultraviolet radiation are compared. The methods included are spectroradiometric, erythemally weighted broadband and multi-channel measurements. The comparison of the different methods is based on a literature review and assessments of optical characteristics of the spectroradiometer Optronic 742 of the Finnish Centre for Radiation and Nuclear Safety (STUK) and of the erythemally weighted Robertson-Berger type broadband radiometers Solar Light models 500 and 501 of the Finnish Meteorological Institute and STUK. An introduction to the sources of error in solar UV measurements, to methods for radiometric characterization of UV radiometers together with methods for error reduction are presented. Reviews on experiences from world-wide UV monitoring efforts and instrumentation as well as on the results from international UV radiometer intercomparisons are also presented. (62 refs.).

  20. VOYAGER OBSERVATIONS OF THE DIFFUSE FAR-ULTRAVIOLET RADIATION FIELD

    International Nuclear Information System (INIS)

    The two Voyager spacecraft have completed their planetary exploration mission and are now probing the outer realms of the heliosphere. The Voyager ultraviolet spectrometers continued to operate well after the Voyager 2 Neptune encounter in 1989. We present a complete database of diffuse radiation observations made by both Voyagers: a total of 1943 spectra (500-1600 Å) scattered throughout the sky. These include observations of dust-scattered starlight, emission lines from the hot interstellar medium, and a number of locations where no diffuse radiation was detected, with the very low upper limit of about 25 photons cm–2 s–1 sr–1 Å–1. Many of these observations were from late in the mission when there was significantly less contribution from interplanetary emission lines and thus less contamination of the interstellar signal.

  1. Thermoluminescent behavior of diamond thin films exposed to ultraviolet radiation

    International Nuclear Information System (INIS)

    In this work the thermoluminescent properties of diamond thin films are discussed which are grown up through the chemical vapor method exposed to ultraviolet radiation of 200-280 nm. The films with thickness 3, 6, 9, 12, 180 and 500 microns were grown up using a precursor gas formed of H2-CH4-CO excited through microwave energy or hot filament.The structure and morphology of the films were examined through scanning electron microscopy, indicating the formation of different diamond polycrystal structures which depend on the type of heating of the precursor gas used as well as the film dimensions. In general, the brilliance curve depends on the sample and the wavelength of the irradiation ultraviolet light, however it presents clearly thermoluminescence bands in 148, 160, 272, 304, 320 and 324 C degrees. The maximum of the thermoluminescence efficiency is obtained for the case of sample exposure with light of 214 nm. The sample of 500 microns is what exhibits greater thermoluminescent efficiency of those studied samples. The thermoluminescent behavior in function of radiation dose presents regions of linearity and supra linearity for higher and small doses respectively. The disappearance of the thermoluminescent signal depends on the characteristics of the film and it can reach until a 30 % of loss before to reach the stability. (Author)

  2. Sterilization techniques without heating (ultraviolet ray, radiation and ozone)

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Hitoshi (Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment)

    1991-01-01

    The recent demand of consumers for processed foods is characterized by the intention for health and nature, besides, the demand for low sweetness, salt reduction, no additive and freshness becomes strong. In view of the control of microorganisms in products, all these become the negative factors. Accordingly, in order to overcome them, it is urgently desired to develop new technology or to improve conventional methods. As to heating sterilization, the uniform temperature treatment to the inside of foods is difficult, and it cannot be applied to perishables. The high temperature sterilization above 120degC causes the change in nutrition composition and physical properties. Ultraviolet ray and ozone can be used for the sterilization of food surface and powder and liquid foods. Radiation treatment can be applied to packed foods and frozen foods as well as food surface. The principle and the fields of application of ultraviolet ray sterilization, radiation sterilization and ozone sterilization are reported. In the mechanism of these methods, the action to DNA and oxidation are common. (K.I.).

  3. Sterilization techniques without heating (ultraviolet ray, radiation and ozone)

    International Nuclear Information System (INIS)

    The recent demand of consumers for processed foods is characterized by the intention for health and nature, besides, the demand for low sweetness, salt reduction, no additive and freshness becomes strong. In view of the control of microorganisms in products, all these become the negative factors. Accordingly, in order to overcome them, it is urgently desired to develop new technology or to improve conventional methods. As to heating sterilization, the uniform temperature treatment to the inside of foods is difficult, and it cannot be applied to perishables. The high temperature sterilization above 120degC causes the change in nutrition composition and physical properties. Ultraviolet ray and ozone can be used for the sterilization of food surface and powder and liquid foods. Radiation treatment can be applied to packed foods and frozen foods as well as food surface. The principle and the fields of application of ultraviolet ray sterilization, radiation sterilization and ozone sterilization are reported. In the mechanism of these methods, the action to DNA and oxidation are common. (K.I.)

  4. Outdoor Exposure to Solar Ultraviolet Radiation and Legislation in Brazil.

    Science.gov (United States)

    Silva, Abel A

    2016-06-01

    The total ozone column of 265 ± 11 Dobson Units in the tropical-equatorial zones and 283 ± 16 Dobson Units in the subtropics of Brazil are among the lowest on Earth, and as a result, the prevalence of skin cancer due to solar ultraviolet radiation is among the highest. Daily erythemal doses in Brazil can be over 7,500 J m. Erythemal dose rates on cloudless days of winter and summer are typically about 0.147 W m and 0.332 W m, respectively. However, radiation enhancement events yielded by clouds have been reported with erythemal dose rates of 0.486 W m. Daily doses of the diffuse component of erythemal radiation have been determined with values of 5,053 J m and diffuse erythemal dose rates of 0.312 W m. Unfortunately, Brazilians still behave in ways that lead to overexposure to the sun. The annual personal ultraviolet radiation ambient dose among Brazilian youths can be about 5.3%. Skin cancer in Brazil is prevalent, with annual rates of 31.6% (non-melanoma) and 1.0% (melanoma). Governmental and non-governmental initiatives have been taken to increase public awareness of photoprotection behaviors. Resolution #56 by the Agência Nacional de Vigilância Sanitária has banned tanning devices in Brazil. In addition, Projects of Law (PL), like PL 3730/2004, propose that the Sistema Único de Saúde should distribute sunscreen to members of the public, while PL 4027/2012 proposes that employers should provide outdoor workers with sunscreen during professional outdoor activities. Similar laws have already been passed in some municipalities. These are presented and discussed in this study. PMID:27115230

  5. Surface ultraviolet radiation over east Siberia: seasonal variations

    Directory of Open Access Journals (Sweden)

    A. V. Mikhalev

    Full Text Available The results of spectral measurements of the daily near-noon surface direct solar ultraviolet radiation in the wavelength range of 295–345 nm obtained in Irkutsk (East Siberia for the time interval of 1998–2000 are presented. For the period under consideration, the seasonal UV radiation variations are analysed that are associated with the total ozone dynamics, the transition of cyclonic and anticyclonic (Siberian anticyclone periods, the presence of snow cover, and other factors. The analysis reveals an asymmetric behaviour of the seasonal course in ground-level UV radiation around the time of the summer solstice, with seasonal variation dependence on the wavelength. We have determined the irregular variations of surface UV radiation that is typical for the region, with their properties dependent on the season and on the spectral range analysed. The similarity of the above noted features from year to year was revealed.

    Key words. Atmospheric composition and structure (Transmission and scattering of radiation; instruments and techniques – Meteorology and atmospheric dynamics (middle atmosphere dynamics

  6. GaN-Based Heterojunction Structures for Simultaneous Detection of Ultraviolet/Infrared Radiation

    Science.gov (United States)

    Jayasinghe, R.; Ariyawansa, G.; Dietz, N.; Perera, A. G. U.; Matsik, S.; Ferguson, I.; Laframboise, S.; Bezinger, A.; Buchanan, M.; Liu, H. C.

    2009-11-01

    Ultraviolet and infrared (UV/IR) dual-band photodetectors have potential applications in various areas, such as fire/flame detection, solar astronomy, military sensing, situational awareness applications, and combustion process monitoring. Since GaN-based UV/IR detectors do not respond to solar or artificial visible lighting, the false detection rate is strongly reduced. Use of a single detector for detecting UV/IR can also eliminate the difficulties of operating several individual detectors with separate electronics and cooling mechanisms. Here, we report a dual-band detector which simultaneously detects UV (250 -- 360 nm) and IR (5 -- 14 μm) regions, showing near zero spectral crosstalk. This allows the detection of both UV and IR incident radiation, separately identifying the relative strength of each photocurrent component. Further improvements for the detector are also discussed.

  7. Environment and health: 3. Ozone depletion and ultraviolet radiation

    International Nuclear Information System (INIS)

    Ultraviolet radiation from the sun is responsible for a variety of familiar photochemical reactions, including photochemical smog, bleaching of paints and decay of plastics. Conjugated bonds in organic molecules such as proteins and DNA absorb the UV radiation, which can damage these molecules. By a fortunate evolutionary event, the oxygen produced by photosynthesis forms a filter in the outer reaches of our atmosphere that absorbs the most energetic and harmful UV radiation, with wavelengths below 240 nm (in the UVC band [wavelength 100-280 nm]). In the process, the oxygen molecules split up and recombine to form ozone (Fig. 1). This ratified ozone layer (spread out between 10 and 50 Ion in the stratosphere but only 3 mm thick were it compressed at ground level) in turn efficiently absorbs UV radiation of higher wavelengths (tip to about 310 nm). A part of the UV radiation in the UVB band (wavelength 280-315 nm) still reaches ground level and is absorbed in sufficient amounts to have deleterious effects on cells. The less energetic radiation in the UVA band (wavelength 315-400 nm, bordering the visible band [wavelength 400-800 nm]) is not absorbed by ozone and reaches ground level without much attenuation through a clear atmosphere (i.e., no clouds, no air pollution). Although not completely innocuous, the UVA radiation in sunlight is much less photochemically active and therefore generally less harmful than UVB radiation. Life on earth has adapted itself to the UV stress, particularly UVB stress, fbr example by forming protective UV-absorbing surface layers, by repairing cell damage or by replacing damaged cells entirely. Human skin shows all of these adaptive features. Our eyes are less well adapted, but dicy, are shielded by the brows and by squinting. (author)

  8. Ultraviolet sterilization

    International Nuclear Information System (INIS)

    Artificial ultraviolet radiation sources can supply bactericidal energy in such a high dosage that in less than a second a higher degree of disinfection is accomplished than by sun irradiation in hours. Bacteria, viruses, phages, and organic micropollutants can be degraded by photochemical wet combustion down to and below detection limits of organic carbon. There are no known ultraviolet-resistant microorganisms. There are limitations to ultraviolet treatment which can often be overcome by adequate technical measures. Unlike other water purification processes, ultraviolet irradiation only exterminates living organisms. The radiation must be able to penetrate to the objects of the kill; in a dose large enough to kill, and long enough to kill and prevent new growth. Contrary to filters, ultraviolet flow-through reactors do not restrict free flow significantly. In contrast to distillation, ultraviolet irradiation imposes no phase changes to the water. Used as a sequence in ultrapure water systems, maintenance requirements are virtually nonexistent; because of the absence of dissolved and particulate matter in purified water, mechanical cleaning of the photoreactor chambers is not essential. The process is highly economical; energy consumption is low and supervision minimal. 103 refs., 45 figs., 15 tabs

  9. III. Artificial sources of ionizing radiation

    International Nuclear Information System (INIS)

    A theoretical explanation is given of obtaining electrons by thermal emission. The Coolidge X-ray tube is described. The spectral composition is presented of X radiation, changes in the spectrum of X radiation bremsstrahlung in dependence on anode potential and on different shapes of the rectifier of the high voltage curve. X-ray spectrography of crystals is presented as an example of the use of X radiation. Linear accelerators (simple and multiple), microtrons, cyclotrons and betatrons are used for obtaining higher energy radiation. The principle is given for each accelerator and examples of acclerators are given such as are used in clinical practice and in radiotherapy. (E.S.)

  10. Assessment of Solar Ultraviolet A Radiation in Hamadan City

    Directory of Open Access Journals (Sweden)

    N. Rostampour

    2013-01-01

    Full Text Available Introduction & Objective: Biological effects of ultraviolet (UV radiation on the body of live organisms, have been studied by researchers in recent years. UV affects human organs such as skin, eyes and immune system, as well as animals and plants. The main natural source of UV radiation is the Sun. So, the integral observation of UV levels and their effects at ground level is important to determine the present and future environmental and health implications of the solar UV radiation. Since the amount of UVR (UV radiation has not already been measured in Hamadan, the aim of this study was to measure the amount in Hamadan city in different months of the year. Materials & Methods: This work was a cross-sectional study and has assessed the solar UVA radiation, by calibrated Hagner digital radiometer, model EC1 UV-A. The monthly quantity of solar UVR was measured in Hamadan during one year (2011-2012. Results: The maximum UVA received on the ground level was 27.3±1.09 W/m2 in Shahrivar month (Aug 23 – Sep 22 while the minimum was 11.8±1.32 W/m2 in Azar month (Nov 22 – Dec 21 . Total UVA radiation received on the ground level was 19.74±1.56 W/m2 during the period of measurment.Conclusion: According to the results of this study, it seems that the annual UVA in Hamadan city exceeded the amounts recommended by the WHO and further studies are needed to measure UVB and UVC to determine the total UV radiation level in thecity. Based on these results, it is recommended to wear appropriate sunglasses and minimize sun exposure during the midday hours.(Sci J Hamadan Univ Med Sci 2013; 19 (4:69-74

  11. Protective Effect of Chitin Urocanate Nanofibers against Ultraviolet Radiation

    Directory of Open Access Journals (Sweden)

    Ikuko Ito

    2015-12-01

    Full Text Available Urocanic acid is a major ultraviolet (UV-absorbing chromophore. Chitins are highly crystalline structures that are found predominantly in crustacean shells. Alpha-chitin consists of microfibers that contain nanofibrils embedded in a protein matrix. Acid hydrolysis is a common method used to prepare chitin nanofibrils (NFs. We typically obtain NFs by hydrolyzing chitin with acetic acid. However, in the present study, we used urocanic acid to prepare urocanic acid chitin NFs (UNFs and examined its protective effect against UVB radiation. Hos: HR-1 mice coated with UNFs were UVB irradiated (302 nm, 150 mJ/cm2, and these mice showed markedly lower UVB radiation-induced cutaneous erythema than the control. Additionally, sunburn cells were rarely detected in the epidermis of UNFs-coated mice after UVB irradiation. Although the difference was not as significant as UNFs, the number of sunburn cells in mice treated with acetic acid chitin nanofibrils (ANFs tended to be lower than in control mice. These results demonstrate that ANFs have a protective effect against UVB and suggest that the anti-inflammatory and antioxidant effects of NFs influence the protective effect of ANFs against UVB radiation. The combination of NFs with other substances that possess UV-protective effects, such as urocanic acid, may provide an enhanced protective effect against UVB radiation.

  12. Ultraviolet radiation from the pulsed corona discharge in water

    International Nuclear Information System (INIS)

    Quantitative analysis of ultraviolet radiation from the pulsed corona discharge in water with needle-plate electrode geometry (∼1-3 J pulse-1) was performed using the potassium ferrioxalate actinometry. Photon flux J190-280 and radiant energy Q190-280 of the UV light emitted from the discharge at spectral region 190-280 nm was determined in dependence on the applied voltage (17-29 kV, positive polarity) and the solution conductivity (100-500 μS cm-1). The intensity of the UV radiation strongly increased with increasing water conductivity and applied voltage. Depending on the applied voltage the determined photon flux varied by more than two orders of magnitude within the range of solution conductivities 100-500 μS cm-1. It was found that photon flux from the discharge may be directly related to the discharge pulse mean power Pp as J190-280 = 44.33 Pp2.11 (quanta pulse-1). A significant role of UV radiation in the production of hydrogen peroxide and bacterial inactivation by the corona discharge in water has been identified. As the solution conductivity increased the yield of H2O2 produced by the discharge decreased due to increasing photolysis of H2O2 accounting for up to 14% of the total decomposition rate of H2O2. As regards bactericidal effects, it was estimated that the UV radiation contributes about 30% to the overall inactivation of Escherichia coli.

  13. Phototherapy appliances, their ultraviolet radiation and quality assurance of phototherapy

    International Nuclear Information System (INIS)

    Artificial UV radiation (UVR) is used in the treatment of psoriasis and other skin diseases. Long term phototherapy is associated to increased risk of squamous cell carcinoma. This report gives a short review of biological effects of UVR and technical aspects of phototherapy units. The phototherapy units used in Finnish Central hospitals are described and the measured UVR dose rates of these units are presented. In addition, the UVR meters used in hospitals are described and the calibration factors are given for UVR dose rate measurements: Finally, recommendations are given for the quality assurance of photo-therapy units as well as for assessing UVR doses of patients. (orig.)

  14. IMPACT OF SOLAR ULTRAVIOLET-B RADIATION (290-320 NM) UPON MARINE MICROALGAE

    Science.gov (United States)

    For years scientists and laymen alike have casually noted the impact of solar ultraviolet radiation upon the nonhuman component of the biosphere. Stratospheric ozone functions effectively as an ultraviolet screen by filtering out solar radiation in the 220-320 nm waveband as it p...

  15. Thermoluminescent of induced calcite by gamma and ultraviolet radiation

    International Nuclear Information System (INIS)

    Samples of brazilian calcite, exposed to gamma radiation in laboratory and heated at constant rate of 2.70 C/s, showed three glow peaks at 150, 250 and 350 0C in their thermoluminescent emission curves. The analysis of these peaks, using different models, indicated that they follow a second order kinetics; it has been obtained, for the activation energy, 1.3, 1.5 and 1.7 eV, and, for the pre-exponential factors, 8.1 x 10 14, 6.8 x10 13 and 2.4 x 1012 s-1. Although the total thermoluminescent emission has stayed constant, the relative height of glow peaks has changed with the temperature of annealing in the range of 400 to 700 0C. Exposed samples were also illuminated with ultraviolet light and the resultant curves showed partial or total bleaching or some glow peaks and the growth of peaks at lower temperatures. Samples of virgin calcite, submited to increasing exposures of gamma rays, showed a corresponding enhancement of the optical absorption bands in the range of 25000 to 47000 cm-1 A subsequent illumination of these samples with ultraviolet light produced a decrease of the optical absorption bands at the same range. (author)

  16. Ultraviolet Radiative Transfer Modeling of Nearby Galaxies with Extraplanar Dusts

    CERN Document Server

    Shinn, Jong-Ho

    2015-01-01

    In order to examine their relation to the host galaxy, the extraplanar dust of six nearby galaxies are modeled, employing a three dimensional Monte Carlo radiative transfer code. The targets are from the highly-inclined galaxies that show dust-scattered ultraviolet halos, and the archival Galaxy Evolution Explorer FUV band images were fitted with the model. The observed images are in general well reproduced by two dust layers and one light-source layer, whose vertical and radial distributions have exponential profiles. We obtained several important physical parameters, such as star formation rate (SFR_UV), face-on optical depth, and scale-heights. Three galaxies (NGC 891, NGC 3628, and UGC 11794) show clear evidence for the existence of extraplanar dust layer. However, it is found that the rest three targets (IC 5249, NGC 24, and NGC 4173) do not necessarily need a thick dust disk to model the ultraviolet (UV) halo, because its contribution is too small and the UV halo may be caused by the wing part of the GA...

  17. Ultraviolet radiation for the sterilization of contact lenses

    International Nuclear Information System (INIS)

    Two sources of ultraviolet (UV) radiation with peak wavelengths in the UV-C or UV-B ranges were compared for their ability to sterilize contact lenses infected with Pseudomonas aeruginosa, Streptococcus pneumoniae, Acanthamoeba castellani, Candida albicans, and Aspergillus niger. Also examined was the effect of prolonged UV light exposure on soft and rigid gas permeable (RGP) contact lenses. The UV-C lamp (253.7 nm, 250 mW/cm2 at 1 cm) was germicidal for all organisms within 20 minutes but caused destruction of the soft lens polymers within 6 hours of cumulative exposure. UV-C caused damage to RGP lenses in less than 100 hours. The UV-B lamp (290-310 nm, 500 mW/cm2 at 1 cm) was germicidal for all organisms tested (except Aspergillus) with a 180-minute exposure and caused less severe changes in the soft lens polymers than did the UV-C lamp, although cumulative exposure of 300 hours did substantially weaken the soft lens material. RGP materials were minimally affected by exposure to 300 hours of UV-B. Ultraviolet light is an effective germicidal agent but is injurious to soft lens polymers; its possible utility in the sterilization of RGP lenses and lens cases deserves further study

  18. Ultraviolet radiation and autoimmune disease: insights from epidemiological research

    International Nuclear Information System (INIS)

    This review examines the epidemiological evidence that suggests ultraviolet radiation (UVR) may play a protective role in three autoimmune diseases: multiple sclerosis, insulin-dependent diabetes mellitus and rheumatoid arthritis. To date, most of the information has accumulated from population studies that have studied the relationship between geography or climate and autoimmune disease prevalence. An interesting gradient of increasing prevalence with increasing latitude has been observed for at least two of the three diseases. This is most evident for multiple sclerosis, but a similar gradient has been shown for insulin-dependent diabetes mellitus in Europe and North America. Seasonal influences on both disease incidence and clinical course and, more recently, analytical studies at the individual level have provided further support for a possible protective role for UVR in some of these diseases but the data are not conclusive. Organ-specific autoimmune diseases involve Th1 cell-mediated immune processes. Recent work in photoimmunology has shown ultraviolet B (UVB) can specifically attenuate these processes through several mechanisms which we discuss. In particular, the possible contribution of an UVR-induced increase in serum vitamin D (1,25(OH)2D3) levels in the beneficial immunomodulation of these diseases is discussed

  19. Formation of globular clusters induced by external ultraviolet radiation II: Three-dimensional radiation hydrodynamics simulations

    CERN Document Server

    Abe, Makito; Hasegawa, Kenji

    2016-01-01

    We explore the possibility of the formation of globular clusters under ultraviolet (UV) background radiation. One-dimensional spherical symmetric radiation hydrodynamics (RHD) simulations by Hasegawa et al. have demonstrated that the collapse of low-mass (10^6-10^7 solar masses) gas clouds exposed to intense UV radiation can lead to the formation of compact star clusters like globular clusters (GCs) if gas clouds contract with supersonic infall velocities. However, three-dimensional effects, such as the anisotropy of background radiation and the inhomogeneity in gas clouds, have not been studied so far. In this paper, we perform three-dimensional RHD simulations in a semi-cosmological context, and reconsider the formation of compact star clusters in strong UV radiation fields. As a result, we find that although anisotropic radiation fields bring an elongated shadow of neutral gas, almost spherical compact star clusters can be procreated from a "supersonic infall" cloud, since photo-dissociating radiation supp...

  20. Drinking water disinfection by means of ultraviolet radiation

    International Nuclear Information System (INIS)

    The book presents all lectures held during a course at Technical Academy Esslingen, on September 10, 1985, on the subject of 'Drinking water disinfection by means of ultraviolet radiation'. The methods hitherto used for disinfection are no longer suitable because of the increasing amounts of organic pollutants found in the untreated water, and because of the necessity to make drinking water disinfection less expensive, non-polluting and thus environmentally compatible. U.V. irradiation is a method allowing technically simple and safe disinfection of the water, and also does not have any effect on the natural taste of the drinking water. The lectures presented discuss all aspects of the method, the equipment, and the performance of irradiation systems in practice. (orig./PW)

  1. The Far-Ultraviolet Radiation from Elliptical Galaxies

    CERN Document Server

    Dorman, B

    1997-01-01

    Since the discovery of the Ultraviolet Upturn Phenomenon (``UVX'') in early-type galaxies it has been clear that the stellar populations of such systems contain an unexpected hot component. Recent work has provided strong circumstantial evidence that the stars radiating at short wavelengths (< 2000 Angstrom) is in fact due to hot horizontal branch, post-HB stars and post-AGB stars. We summarize the arguments in favour of this hypothesis. We then derive an estimate for the fraction of all HB stars that must be contributing to the UV upturn phenomenon in the strongest UVX galaxy, NGC 1399, and derive a hot star fraction f_H ~ 0.16.The implication is that UVX arises from a minority fraction of the dominant stellar population. We conclude that the mechanism that produces the UVX is not one that can be explained naturally by the presence of an extremely metal-rich or metal-poor population.

  2. Ocular effects of ultraviolet radiation from 295 to 365 nm

    International Nuclear Information System (INIS)

    A 5,000 watt Xe--Hg source and a double monochromator were used to produce 6.6 nm full band-pass ultraviolet (UV) radiation. Pigmented rabbit eyes were exposed to the 6.6 nm band-pass UV radiant energy in 5 nm steps from 295 to 320 nm and at random intervals above 320 nm. Corneal and lenticular damage was assessed and classified with a biomicroscope. Corneal threshold radiant exposure (Hc) rose very rapidly from 0.022 Jcm-2 at 300 nm to 10.99 Jcm-2 at 335 nm. Radiant exposures exceeding 2 x Hc resulted in irreversible corneal damage. Lenticular damage was limited to wavebands above 295 nm. The action spectrum for the lens began at 295 nm and extended to about 315 nm. Permanent lenticular damage occurred at radiant exposure levels approximately twice the threshold for lenticular radiant exposure. The importance in establishing both corneal and lenticular damage criteria is emphasized

  3. Pollen and spores as a passive monitor of ultraviolet radiation

    Directory of Open Access Journals (Sweden)

    Wesley Toby Fraser

    2014-04-01

    Full Text Available Sporopollenin is the primary component of the outer walls of pollen and spores. The chemical composition of sporopollenin is responsive to levels of ultraviolet (UV radiation exposure, via a concomitant change in the concentration of phenolic compounds. This relationship offers the possibility of using fossil pollen and spore chemistry as a novel proxy for past UV flux. Phenolic compounds in sporopollenin can be quantified using Fourier Transform infrared spectroscopy. The high potential for preservation of pollen and spores in the geologic record, and the conservative nature of sporopollenin chemistry across the land plant phylogeny, means that this new proxy has the potential to reconstruct UV flux over much longer timescales than has previously been possible. This new tool has important implications for understanding the relationship between UV flux, solar insolation and climate in the past, as well as providing a possible means of assessing paleoaltitude, and ozone thickness.

  4. Long-term visual health risks from solar ultraviolet radiation

    International Nuclear Information System (INIS)

    Ocular exposure to the ultraviolet radiation (UV) contained in sunlight may result in long-term visual health problems. UV plays a role in the etiology of cataracts and possibly in the etiology of visual impairments associated with solar retinopathy, retinopathy of prematurity, ocular aging, cystoid macular edema, retinitis pigmentosa, and senile macular degeneration. The exact does relationships between known UV bioeffects and these ocular problems is, however, uncertain. Thus, there are questions about the extent to which protective measures should be taken to reduce UV exposure of the eye. This paper identifies the long-term visual health problems potentially associated with ocular exposure to solar UV; proposes worst-case assumptions for the role of solar UV in these visual problems; and recommends protective measures based on damage thresholds and worst-case assumptions

  5. Distinctive molecular responses to ultraviolet radiation between keratinocytes and melanocytes.

    Science.gov (United States)

    Sun, Xiaoyun; Kim, Arianna; Nakatani, Masashi; Shen, Yao; Liu, Liang

    2016-09-01

    Solar ultraviolet radiation (UVR) is the major risk factor for skin carcinogenesis. To gain new insights into the molecular pathways mediating UVR effects in the skin, we performed comprehensive transcriptomic analyses to identify shared and distinctive molecular responses to UVR between human keratinocytes and melanocytes. Keratinocytes and melanocytes were irradiated with varying doses of UVB (10, 20 and 30 mJ/cm(2) ) then analysed by RNA-Seq at different time points post-UVB radiation (4, 24 and 72 h). Under basal conditions, keratinocytes and melanocytes expressed similar number of genes, although they each expressed a distinctive subset of genes pertaining to their specific cellular identity. Upon UVB radiation, keratinocytes displayed a clear pattern of time- and dose-dependent changes in gene expression that was different from melanocytes. The early UVB-responsive gene set (4 h post-UVR) differed significantly from delayed UVB-responsive gene sets (24 and 72 h). We also identified multiple novel UVB signature genes including PRSS23, SERPINH1, LCE3D and CNFN, which were conserved between melanocyte and keratinocyte lines from different individuals. Taken together, our findings elucidated both common and distinctive molecular features between melanocytes and keratinocytes and uncovered novel UVB signature genes that might be utilized to predict UVB photobiological effects on the skin. PMID:27119462

  6. Perception of natural, medical, and 'artificial' radiation exposures

    International Nuclear Information System (INIS)

    The paper discusses the imbalances in public perception and weighting factors attached by the media and consequently by politicians and by the general public, to the risks associated with the three main sources of population exposure, namely: natural radiation, diagnostic or therapeutic medical exposure and other artificial components including nuclear weapons tests, nuclear fuel cycles and reactor accidents. 15 refs

  7. Influence of pre sowing ultraviolet radiation of wheat seeds on its growth, efficiency and activity of endogenous phytohormones

    International Nuclear Information System (INIS)

    The experimental data on influence of ultraviolet radiation on growth, efficiency and activity of endogenous phytohormones of wheat seeds was considered in this work. It was shown that short-wave ultraviolet radiation decreased the growth processes of plants. The medium-wave and long-wave ultraviolet radiation increased the the growth processes of plants.

  8. Ultraviolet radiation from the pulsed corona discharge in water

    Energy Technology Data Exchange (ETDEWEB)

    Lukes, Petr; Clupek, Martin; Babicky, Vaclav; Sunka, Pavel [Institute of Plasma Physics, Department of Pulse Plasma Systems, Academy of Sciences of the Czech Republic, v.v.i., Za Slovankou 3, 182 00 Prague 8 (Czech Republic)], E-mail: lukes@ipp.cas.cz

    2008-05-01

    Quantitative analysis of ultraviolet radiation from the pulsed corona discharge in water with needle-plate electrode geometry ({approx}1-3 J pulse{sup -1}) was performed using the potassium ferrioxalate actinometry. Photon flux J{sub 190-280} and radiant energy Q{sub 190-280} of the UV light emitted from the discharge at spectral region 190-280 nm was determined in dependence on the applied voltage (17-29 kV, positive polarity) and the solution conductivity (100-500 {mu}S cm{sup -1}). The intensity of the UV radiation strongly increased with increasing water conductivity and applied voltage. Depending on the applied voltage the determined photon flux varied by more than two orders of magnitude within the range of solution conductivities 100-500 {mu}S cm{sup -1}. It was found that photon flux from the discharge may be directly related to the discharge pulse mean power P{sub p} as J{sub 190-280} = 44.33 P{sub p}{sup 2.11} (quanta pulse{sup -1}). A significant role of UV radiation in the production of hydrogen peroxide and bacterial inactivation by the corona discharge in water has been identified. As the solution conductivity increased the yield of H{sub 2}O{sub 2} produced by the discharge decreased due to increasing photolysis of H{sub 2}O{sub 2} accounting for up to 14% of the total decomposition rate of H{sub 2}O{sub 2}. As regards bactericidal effects, it was estimated that the UV radiation contributes about 30% to the overall inactivation of Escherichia coli.

  9. Physical and biological characterization of a seawater ultraviolet radiation sterilizer

    International Nuclear Information System (INIS)

    The physical and biological characterization of a seawater ultraviolet (UV) sterilizer is described. The physical characterization was performed using radiochromic dye films by evaluating the uniformity of the radiant exposure along each lamp, the effect of the radiation from one lamp on the array of adjacent lamps, and by measuring the UV radiation absorption of seawater with respect to distilled water. The biological characterization was performed by measuring the amount of reduction of bacteria in stored seawater after different filtration and UV treatments. Among the filtration methods tested, differential filtration (5, 3 and 0.45 μm filters connected in series) caused the highest bacterial reduction factor of 60%. UV radiant exposures of 212, 424, 636 and 848 J m-2 yielded bacteria reduction factors of 99.86, 99.969, 99.997 and 100%, respectively, for populations of Vibrio and Pseudomonas bacteria present in stored seawater. It is concluded that the system is useful for water disinfection when 1, 2 or 3 lamps are on; when 4 lamps are used the treated water becomes sterile. (author)

  10. Physical factors in cataractogenesis: ambient ultraviolet radiation and temperature

    International Nuclear Information System (INIS)

    A number of environmental cofactors have been implicated in cataracto-genesis. Two have received the greatest attention: ultraviolet radiation (UVR) and ambient temperature. Unfortunately, both temperature and UVR levels vary similarly with geographical latitude. Careful attention to several more refined physical variables and the geometry of exposure may permit investigators to separate the contributory effects of these two physical agents. This paper briefly reviews the available data, estimates the variation of lenticular temperature with ambient temperature, and provides measurements of short-wavelength (UV-B) UVR exposure to the human eye with different meterological conditions. The study attempts to provide epidemiological investigators with more detailed information necessary to perform more accurate studies of cataract and other ocular pathologies that appear to be related to environmental factors. Ocular UV-B radiation exposure levels were measured at nine locations in the USA near 40 degrees latitude at elevations from sea level to 8000 ft. Terrain reflectance is shown to be much more important than terrain elevation; cloud cover and haze may actually increase ocular exposure; and the value of wearing brimmed hats and spectacles varies with the environment. Several avenues for future research are suggested

  11. Ultraviolet Radiative Transfer Modeling of Nearby Galaxies with Extraplanar Dusts

    Science.gov (United States)

    Shinn, Jong-Ho; Seon, Kwang-Il

    2015-12-01

    In order to examine their relation to the host galaxy, the extraplanar dusts of six nearby galaxies are modeled, employing a three-dimensional Monte Carlo radiative transfer code. The targets are from the highly inclined galaxies that show dust-scattered ultraviolet halos, and the archival Galaxy Evolution Explorer FUV band images were fitted with the model. The observed images are generally well-reproduced by two dust layers and one light source layer, whose vertical and radial distributions have exponential profiles. We obtained several important physical parameters, such as star formation rate (SFRUV), face-on optical depth, and scale-heights. Three galaxies (NGC 891, NGC 3628, and UGC 11794) show clear evidence for the existence of an extraplanar dust layer. However, it is found that the remaining three targets (IC 5249, NGC 24, and NGC 4173) do not necessarily need a thick dust disk to model the ultraviolet (UV) halo, because its contribution is too small and the UV halo may be caused by the wing part of the GALEX point spread function. This indicates that the galaxy samples reported to have UV halos may be contaminated by galaxies with negligible extraplanar (halo) dust. The galaxies showing evidence of an extraplanar dust layer fall within a narrow range on the scatter plots between physical parameters such as SFRUV and extraplanar dust mass. Several mechanisms that could possibly produce the extraplanar dust are discussed. We also found a hint that the extraplanar dust scale-height might not be much different from the polycyclic aromatic hydrocarbon emission characteristic height.

  12. Ultraviolet radiation as disinfection for fish surgical tools

    Energy Technology Data Exchange (ETDEWEB)

    Walker, Ricardo W.; Markillie, Lye Meng; Colotelo, Alison HA; Geist, David R.; Gay, Marybeth E.; Woodley, Christa M.; Eppard, M. B.; Brown, Richard S.

    2013-04-04

    Telemetry is frequently used to examine the behavior of fish, and the transmitters used are normally surgically implanted into the coelomic cavity of fish. Implantation requires the use of surgical tools such as scalpels, forceps, needle holders, and sutures. When fish are implanted consecutively, as in large telemetry studies, it is common for surgical tools to be sterilized or, at minimum, disinfected between each use so that pathogens that may be present are not spread among fish. To determine the efficacy for this application, ultraviolet (UV) radiation was used to disinfect surgical tools exposed to one of four aquatic organisms that typically lead to negative health issues for salmonids. These organisms included Aeromonas salmonicida, Flavobacterium psychrophilum, Renibacterium salmoninarum, and Saprolegnia parasitica, causative agents of furunculosis, coldwater disease, bacterial kidney disease, and saprolegniasis (water mold), respectively. Four experiments were conducted to address the question of UV efficacy. In the first experiment, forceps were exposed to the three bacteria at three varying concentrations. After exposure to the bacterial culture, tools were placed into a mobile Millipore UV sterilization apparatus. The tools were then exposed for three different time periods – 2, 5, or 15 min. UV radiation exposures at all durations were effective at killing all three bacteria on forceps at the highest bacteria concentrations. In the second experiment, stab scalpels, sutures, and needle holders were exposed to A. salmonicida using the same methodology as used in Experiment 1. UV radiation exposure at 5 and 15 min was effective at killing A. salmonicida on stab scalpels and sutures but not needle holders. In the third experiment, S. parasitica, a water mold, was tested using an agar plate method and forceps-pinch method. UV radiation was effective at killing the water mold at all three exposure durations. Collectively, this study shows that UV

  13. Potential of herbs in skin protection from ultraviolet radiation

    Directory of Open Access Journals (Sweden)

    Radava R Korać

    2011-01-01

    Full Text Available Herbs have been used in medicines and cosmetics from centuries. Their potential to treat different skin diseases, to adorn and improve the skin appearance is well-known. As ultraviolet (UV radiation can cause sunburns, wrinkles, lower immunity against infections, premature aging, and cancer, there is permanent need for protection from UV radiation and prevention from their side effects. Herbs and herbal preparations have a high potential due to their antioxidant activity, primarily. Antioxidants such as vitamins (vitamin C, vitamin E, flavonoids, and phenolic acids play the main role in fighting against free radical species that are the main cause of numerous negative skin changes. Although isolated plant compounds have a high potential in protection of the skin, whole herbs extracts showed better potential due to their complex composition. Many studies showed that green and black tea (polyphenols ameliorate adverse skin reactions following UV exposure. The gel from aloe is believed to stimulate skin and assist in new cell growth. Spectrophotometer testing indicates that as a concentrated extract of Krameria triandra it absorbs 25 to 30% of the amount of UV radiation typically absorbed by octyl methoxycinnamate. Sesame oil resists 30% of UV rays, while coconut, peanut, olive, and cottonseed oils block out about 20%. A "sclerojuglonic" compound which is forming from naphthoquinone and keratin is the reaction product that provides UV protection. Traditional use of plant in medication or beautification is the basis for researches and making new trends in cosmetics. This review covers all essential aspects of potential of herbs as radioprotective agents and its future prospects.

  14. Potential of herbs in skin protection from ultraviolet radiation.

    Science.gov (United States)

    Korać, Radava R; Khambholja, Kapil M

    2011-07-01

    Herbs have been used in medicines and cosmetics from centuries. Their potential to treat different skin diseases, to adorn and improve the skin appearance is well-known. As ultraviolet (UV) radiation can cause sunburns, wrinkles, lower immunity against infections, premature aging, and cancer, there is permanent need for protection from UV radiation and prevention from their side effects. Herbs and herbal preparations have a high potential due to their antioxidant activity, primarily. Antioxidants such as vitamins (vitamin C, vitamin E), flavonoids, and phenolic acids play the main role in fighting against free radical species that are the main cause of numerous negative skin changes. Although isolated plant compounds have a high potential in protection of the skin, whole herbs extracts showed better potential due to their complex composition. Many studies showed that green and black tea (polyphenols) ameliorate adverse skin reactions following UV exposure. The gel from aloe is believed to stimulate skin and assist in new cell growth. Spectrophotometer testing indicates that as a concentrated extract of Krameria triandra it absorbs 25 to 30% of the amount of UV radiation typically absorbed by octyl methoxycinnamate. Sesame oil resists 30% of UV rays, while coconut, peanut, olive, and cottonseed oils block out about 20%. A "sclerojuglonic" compound which is forming from naphthoquinone and keratin is the reaction product that provides UV protection. Traditional use of plant in medication or beautification is the basis for researches and making new trends in cosmetics. This review covers all essential aspects of potential of herbs as radioprotective agents and its future prospects. PMID:22279374

  15. Health impacts of ultraviolet radiation in urban ecosystems: a review

    Science.gov (United States)

    Heisler, Gordon M.

    2005-08-01

    This paper explores the literature on ultraviolet irradiance (UV) in urban ecosystems with respect to the likely effects on human health. The focus was the question of whether the health effects of UV radiation should be included in planning of landscape elements such as trees and shading structures. In examining the literature, special attention was given to seeking information on the question of whether it is important that shade be provided for elementary school play areas, and if so, how should it be accomplished? Before such practical questions could be dealt with, it became obvious that answers to several pertinent secondary questions had to be sought. Foremost of these was, what are the negative and positive health effects of UV exposure? Recent epidemiological findings of apparent benefits of sunlight because of vitamin-D photosynthesis and resulting anti-cancer effects make this highly relevant. Another basic question is that of trends in ozone depletion, which leads to interesting questions of long-term trends, short-term extremes, and urban influences on UV irradiance. A host of these and other pertinent questions, such as, "What is the relationship between climate of a location and dress," i.e., "How much exposure will people receive during time spent outdoors?" require much more study. Judging from current knowledge of typical spectra of solar radiation in tree shade and the difference between the action spectra for vitamin D synthesis and erythema in human skin, exposure to solar radiation in tree shade for a short period of time can be somewhat more beneficial for vitamin D synthesis and regulation than detrimental in producing sunburn.

  16. Solar ultraviolet hazards

    International Nuclear Information System (INIS)

    The paper discussed the following subjects: the sources of ultraviolet radiation, solar ultraviolet radiation definition, effects of over exposure to solar ultraviolet radiation, exposure limits and radiation protection of this radiation

  17. Polarized angular distributions of parametric x radiation and vacuum-ultraviolet transition radiation from relativistic electrons

    International Nuclear Information System (INIS)

    We present quantifiable images of the angular distributions (AD's) of parametric x radiation (PXR), and vacuum-ultraviolet transition radiation (vuv TR) from 230 MeV electrons interacting with a silicon crystal. Both AD's are highly polarized. The vuv TR and optical TR data provide measurements of the beam energy and effective divergence angle. Using these quantities and separately known values of the electronic susceptibility |χ0|, we show that the measured PXR AD is in good agreement with the predictions of single crystal theory. Our analysis suggests a method to measure |χ0| using PXR AD's

  18. Ultraviolet radiation is feasible alternative for desinfeting of aerobic and anaerobic treatment systems sewage in Brazil

    International Nuclear Information System (INIS)

    This works shows desinfecting results employing ultraviolet radiation to wastes of sewage treatment station on true scales. Wastes of anaerobic, facultative and maturation pools, septic tank and anaerobic reactor were disinfected. It was found a inactive efficiency to coliforms higher than 99.9%. Safe ultraviolet desinfecting is technically applicable to wastes of sewage treatment station applying aerobic or anaerobic process

  19. The ultraviolet radiation detectors based on wide-bandgap Schottky barrier structures

    CERN Document Server

    Blank, T V; Konstantinov, O V

    2002-01-01

    Recently, much attention has been given to measure and control ultraviolet radiation (UVR) from the Sun and artificial sources. We present photodetectors based on different wide-bandgap surface-barrier structures, which exhibit linear photocurrent-radiant flux characteristics in the range 10 sup - sup 2 -10 sup 3 W/m sup 2 and can register different types of UVR. The use of light filter UFS-6 with GaP photodetector results in a spectral photosensitivity range corresponding to the Sun UV radiation if observed on Earth. The spectral sensitivity range of the photodetectors based on 4H-SiC is near the spectrum of relative effectiveness of various wavelengths in bactericidal UVR. The photosensitivity of the surface-barrier photodetectors based on wide-bandgap semiconductors exhibits the essential decline in the short-wavelength UVR region (5-6 eV), which is the region of intrinsic absorption of the semiconductor. We propose a hot exciton model, according to which the hot excitons can form in the process of the pho...

  20. A Fast Determination of DNA Mutation Induced by Ultraviolet Radiation

    Institute of Scientific and Technical Information of China (English)

    LuFeng; LiuLili; ZhangXiaofang; WuYutian

    2001-01-01

    Electrophoresis, chromatography, immunoassay, sequencing and other time consuming ap-proaches have been developed to determine DNA base mismatching, oxidative lesion or strand breaks. Sometimes,however, only qualitative information is enough to decide whether mutation has happened to DNA and its extent.Convolution spectrometry (CS), a new technique to discover ultrafme difference on ultraviolet (UV) absorption ofdifferent substances, is originally employed to find out any subtle mutation of DNA induced by UV radiation. Muta-tive DNA is compared with ego criteria based on the spectra of the former DNA, any difference is quantitatively ex-pressed by dispersion (5). Visible changes cannot be observed on second -derivative spectra until the mutation gets 5up to 11.48%. Dimethyl sulfoxide is an intensifier of UV 254 nm induced DNA mutation and protector at 365 nm,which is simply confirmed by increasing and decreasing 5. Every convolution procedure takes less than 1 min. Convolution spectrometry provides a fast, simple, sensitive and inexpensive alternative to determine DNA mutation, andto screen anti-mutational medicines.

  1. The action of ultraviolet radiation on sorption properties of the liver, kidney and heart tissues

    International Nuclear Information System (INIS)

    Data are presented on the effect of ultraviolet (UV) radiation on sorption properties of the liver-, kidney- and heart tissues in rats, testifying to the different role of internal organs tissues in the animal response to UV-irradiation

  2. Effect of ultraviolet radiation on marine phytoplankton community in Akkeshi Bay, Japan

    International Nuclear Information System (INIS)

    Effect of ultraviolet radiation on marine phytoplankton community was determined during a spring and fall bloom in a boreal embayment, Akkeshi Bay, Japan, which was located at 43 degrees N, 144 degrees 50'E. A time-series of observation was made every 6 h for 24 hours. Exposure to ultraviolet radiation always caused a depression of photosynthetic activity was observed at the end of day light period in both blooms. During a nigh period a degree of depression was decreased by 50% at least. The results of the present study may suggest that the effect of ultraviolet radiation on photosynthesis of marine phytoplankton is significantly large even in the boreal sea region and marine phytoplankton community has a capability to recover more than 40% from a damage by ultraviolet radiation during a night period

  3. Ultraviolet Radiation Sensitivity in Cave Bacteria: Evidence of Adaptation to the Subsurface?

    OpenAIRE

    Snider Jessica R.; Goin Caitlin; Miller Robert V.; Boston Penelope J.; Northup Diana E.

    2009-01-01

    We hypothesize that a reduced capacity to withstand or repair cellular damage from ultraviolet radiation may be present in caveadaptedmicroorganisms that never experience such conditions. However, a small number of previous studies have shown that somesubsurface bacteria do not show greater sensitivity to ultraviolet radiation (UVR) than surface bacteria. To estimate UVR sensitivity incave bacteria, bacterial isolates were collected from Carlsbad Cavern, New Mexico, U.S.A., and percent surviv...

  4. Fluorescence of molecular hydrogen excited by solar extreme-ultraviolet radiation

    Science.gov (United States)

    Feldman, P. D.; Fastie, W. G.

    1973-01-01

    During trans-earth coast, the Apollo 17 ultraviolet spectrometer was scheduled to make observations of the far ultraviolet background in selected regions of the sky. In the course of one of these observations, the spacecraft fuel cells were routinely purged of excess hydrogen and water vapor. The ultraviolet fluorescence spectrum of the purged molecular hydrogen excited by solar extreme ultraviolet radiation is interpreted by absorption of solar L-beta and L-gamma radiation in the nearly resonant (6, 0) and (11, 0) Lyman bands. The results are deemed significant for ultraviolet spectroscopic investigations of the atmospheres of the moon and planets since Lyman-band fluorescence provides an unambiguous means of identification of molecular hydrogen in upper atmospheres.

  5. Ultraviolet radiation directly induces pigment production by cultured human melanocytes

    International Nuclear Information System (INIS)

    In humans the major stimulus for cutaneous pigmentation is ultraviolet radiation (UVR). Little is known about the mechanism underlying this response, in part because of the complexity of interactions in whole epidermis. Using a recently developed culture system, human melanocytes were exposed daily to a physiologic range of UVR doses from a solar simulator. Responses were determined 24 hours after the last exposure. There was a dose-related increase in melanin content per cell and uptake of 14C-DOPA, accompanied by growth inhibition. Cells from donors of different racial origin gave proportionately similar increases in melanin, although there were approximately tenfold differences in basal values. Light and electron microscopy revealed UVR-stimulated increases in dendricity as well as melanosome number and degree of melanization, analogous to the well-recognized melanocyte changes following sun exposure of intact skin. Similar responses were seen with Cloudman S91 melanoma cells, although this murine cell line required lower UVR dosages and fewer exposures for maximal stimulation. These data establish that UVR is capable of directly stimulating melanogenesis. Because cyclic AMP elevation has been associated in some settings with increased pigment production by cultured melanocytes, preliminary experiments were conducted to see if the effects of UVR were mediated by cAMP. Both alpha-MSH and isobutylmethylxanthine (IBMX), as positive controls, caused a fourfold increase in cAMP level in human melanocytes and/or S91 cells, but following a dose of UVR sufficient to stimulate pigment production there was no change in cAMP level up to 4 hours after exposure. Thus, it appears that the UVR-induced melanogenesis is mediated by cAMP-independent mechanisms

  6. Ultraviolet radiation and blue-light emissions from spotlights incorporating tungsten halogen lamps

    CERN Document Server

    MacKinlay, Alistair F; Whillock, M J

    1989-01-01

    This report summarises measurements of the ultraviolet radiation and blue-light emissions from eleven 'desk-top' tungsten halogen (quartz) lamps and one 'floor-standing' tungsten halogen (quartz) lamp available in the UK. Values of occupational hazard weighted and erythemally weighted ultraviolet radiation irradiance and measurements and relevant calculations of blue-light hazards are presented. It is concluded that the safety design of some desk-top tungsten halogen lamps is inadequate to prevent unnecessary exposure of the skin to potentially harmful ultraviolet radiation. It is recommended that all tungsten halogen lamps should have sufficient filtration to reduce their ultraviolet emissions to an acceptably low level. As long as the comfort aversion responses of the eye are respected, direct viewing of the lamps examined should not constitute a retinal hazard.

  7. Enhancement of photosynthesis in Sorghum bicolor by ultraviolet radiation

    International Nuclear Information System (INIS)

    We assessed the influence of ultraviolet radiation (UV) on net photosynthetic CO2 assimilation rate (Pn) in Sorghum bicolor, with particular attention to examining whether UV can enhance Pn via direct absorption of UV and absorption of UV-induced blue fluorescence by photosynthetic pigments. A polychromatic UV response spectrum of leaves was constructed by measuring Pn under different UV supplements using filters that had sharp transmission cut-offs from 280 to 382 nm, against a background of non-saturating visible light. When the abaxial surface was irradiated, Pn averaged 4.6% higher with the UV supplement that cut-off UV at 311 nm, compared to lower and higher UV wavelength supplements. This former supplement differed from higher wavelength supplements by primarily providing more UV between 320 and 350 nm. To assess the possibility of direct absorption of UV by photosynthetic pigments, we measured the absorbance of extracted chlorophylls. Chlorophyll a had absorbance peaks at 340 and 389 nm that were 49 and 72% of that at the sorét peak. Chlorophyll b had absorbance peaks at 315 and 346 nm that were both 35% of that at the sorét peak. Since the epidermis transmits some UV, the strong UV absorbance of chlorophyll implies a potential role for irradiance beyond the bounds of the conventionally defined photosynthetically active radiation waveband (400–700 nm). To assess the role of absorption of UV-induced blue fluorescence, we measured the UV-induced fluorescence excitation and emission spectra of leaves. Abaxial excitation peaked at 328 nm, while emission peaked at 446 nm. In this analysis, we used our abaxial fluorescence excitation spectrum and the UV photosynthetic inhibition spectrum of Caldwell et al. (1986) to weight the UV irradiance with each cut-off filter, thereby estimating the potential contribution of UV-induced blue fluorescence to photosynthesis and the inhibitory effects of UV irradiance on photosynthesis, respectively. With a non

  8. Ultraviolet Radiation and Melanoma: AN Interdisciplinary Risk Assessment

    Science.gov (United States)

    Charache, Darryl H.

    1995-01-01

    A multidisciplinary study involving atmospheric, demographic, and epidemiologic disciplines has been conducted to investigate the relation between ultraviolet (UV) dose and melanoma incidence rate on a global scale. A multiple scattering radiative transfer model has been developed to estimate spectral irradiance and integrated biologically effective dose amounts in the UV-B and UV-A wavelength regime. Global maps of seasonally averaged and peak biologically effective dose on a 1^circ x 1^circ resolution have been created for significant land areas using satellite- and surface-derived atmospheric and topographic data sets. These maps have been coupled with worldwide melanoma incidence rates obtained from the International Agency for Research on Cancer (IARC) database and an ethnically-derived skin type classification system to estimate a "global" biological amplification factor (BAF) for males and females. With these BAFs, future estimates of incidence rates and number of additional melanoma cases that may be expected based on simulated increases in UV dose between the years 1980 -2000 can be estimated under simplifying atmospheric and demographic assumptions. Using worldwide melanoma rates and corresponding UV doses, BAFs of 1.67 and 1.26 were derived for white males and females, respectively. No significant relation was found for non-white skin types. Despite relatively low current incidence rates, projections indicate greater percentage changes in incidence rates at higher latitudes where downward trends in ozone are highest. Greater increases in total number of cases appear in countries having high white skin populations; the increase in total cases in these countries is due primarily to population size rather than estimated increases in UV dose. The integration of atmospheric, epidemiological, and demographic models in this study has established a framework that can be used to improve assessments when more data become available, and can be adapted to analyze

  9. Study of effect ultraviolet radiation on Aspergillus Flavus and Aspergillus Parasiticus

    International Nuclear Information System (INIS)

    In this article the results of ultraviolet radiation effects on Aspergillus Flavus and Aspergillus parasiticus to reach the quality control standards are presented. The purpose was to test the effect of ultraviolet radiation in 254 nanometer wavelength for fungi decontamination with respect to the exposure time of radiation and the distance between samples and radiation source. The ultraviolet radiation effects on plates containing Aspergillus Flavus and Aspergillus Parasiticus fungi were studied in the exposure time duration of 30, to 360 seconds of a fixed distance, and also for variable distances from 10 to 40 cm at a given exposure time. It is shown that in the exposure time of more than 360 second the ultraviolet radiation exposure highly decreases the number of Aspergillus Flavus and Aspergillus Parasiticus fungi colonies. By reducing the distance, the number of colonies decreases and it is minimized at a 10 cm distance in the time exposure of 360 second. The above results show that the ultraviolet radiation is an effective method for food decontamination and can be used in industry

  10. Advances in traceability of solar ultraviolet radiation measurements

    International Nuclear Information System (INIS)

    Measurements of solar ultraviolet radiation (UVR) at STUK (Radiation and Nuclear Safety Authority, Finland) commenced in 1989, five years after the alarming observation of the ozone depletion in the Antarctic and in association with the establishment of the solar UV monitoring network of the Finnish Meteorological Institute. It was soon realised that the instrumentation for solar UVR measurements was far from adequate for the challenging task of measuring the solar UV spectrum. In addition, the intercomparison of lamps used as secondary standards of UV irradiance between the National Standard Laboratories revealed significant discrepancies. In the course of this study, a national lamp-based scale for UV irradiance was established by STUK and subsequently was confirmed with the detector-based scale of the Helsinki University of Technology (HUT). Methods for (i) radiometric testing, (ii) calibration and (iii) data correction were developed for solar UV spectroradiometers and for broadband erythemally weighted (EW) solar UV radiometers. A common opinion in the early 1990s was that EW radiometers were not good enough for solar UV monitoring; spectroradiometers or multi-channel narrow band radiometers were seen as the only option for reliable solar UV radiometry. Later on, several intercomparisons revealed that, without stringent methods of quality control (QC) and quality assurance (QA), even high precision spectroradiometers easily yield UV data erroneous by 20% or more. The reliability of the spectroradiometric solar UVR measurements made by STUK was verified in the Nordic solar UV radiometer intercomparisons in 1993 and 1996 and in the largest European intercomparison of solar UV spectroradiometers in 1997. At STUK, it was considered that the low cost and easy-to-operate EW radiometers also had a role in solar UV monitoring. After developing the calibration methods for EW radiometers and gaining experience in testing of 16 EW radiometers, STUK organised the first

  11. Photostimulated exoemission from some organic compounds. [Mercury-quartz lamp, ultraviolet radiation, and gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Krylova, I.V.; Mel' nikov, M.Ya. (Moskovskij Gosudarstvennyj Univ. (USSR))

    1982-07-01

    Photostimulated exoemission from polyethylene and some organic low-molecular model compounds: C/sub 22/H/sub 46/ and C/sub 19/H/sub 38/O containing functional C=O group, was investigated. Time dependences of intensity of photostimulated exoemission when illuminating with a mercury-quartz lamp and spectral photoemission distribution for initial specimens and for specimens subjected to ultraviolet radiation (photolysis) or /sup 60/Co gamma radiation (radiolysis) have been investigated. The developed approach to the investigation of phenomena of photostimulated emission from organic compounds based on simultaneous recording of photocurrent and photochemical transformations permits to elucidate the formation mechanism of surface traps during illumination, stabilization of charges formed and the trap nature.

  12. Effect of ultraviolet radiation, smoking and nutrition on hair.

    Science.gov (United States)

    Trüeb, Ralph M

    2015-01-01

    Similar to the rest of the skin, the hair is exposed to noxious environmental factors. While ultraviolet radiation (UVR) and smoking are well appreciated as major factors contributing to the extrinsic aging of the skin, their effects on the condition of hair have only lately attracted the attention of the medical community. Terrestrial solar UVR ranges from approximately 290 to 400 nm; UV-B (290-315 nm) reaches only the upper dermis, while the penetration of UV-A (315-400 nm) into the dermis increases with wavelength. The two most important chronic effects of UVR on the skin and bald scalp are photocarcinogenesis and solar elastosis; however, the effects of UVR on hair have largely been ignored. As a consequence of increased leisure time and a growing popularity of outdoor activities and holidays in the sun, the awareness of sun protection of the skin has become important and should also apply to the hair. Besides being the single-most preventable cause of significant cardiovascular and pulmonary morbidity and an important cause of death, the association of tobacco smoking with various adverse effects on the skin and hair has also been recognized. Increasing public awareness of the association between smoking and hair loss seems to offer a good opportunity for the prevention or cessation of smoking, since the appearance of hair plays an important role in the overall physical appearance and self-perception of people. Finally, the quantity and quality of hair are closely related to the nutritional state of an individual. Normal supply, uptake, and transport of proteins, calories, trace elements, and vitamins are of fundamental importance in tissues with high biosynthetic activity, such as the hair follicle. In instances of protein and calorie malnutrition as well as essential amino acid, trace element, and vitamin deficiencies, hair growth and pigmentation may be impaired. Ultimately, important commercial interest lies in the question of whether increasing the

  13. Vacuum-ultraviolet circular dichroism spectrophotometer using synchrotron radiation

    International Nuclear Information System (INIS)

    Full text: Circular dichroism (CD) spectroscopy is powerful for analyzing the structure of optically active materials such as biopolymers. However, no commercial CD spectrophotometer is capable of measuring the CD in the vacuum ultraviolet (VUV) region below 190 nm because of technical difficulties involved in the light source, optical device, and sample cell. CD measurements extended to the VUV region can provide more detailed and new information on the structure of biopolymers based on the higher energy transition of chromophores such as hydroxyl and acetal groups. We have constructed a VUVCD spectrophotometer to measure the CD spectra of biomaterials in aqueous solutions in the 310-140 nm wavelength region under a high vacuum, using a small-scale SR source (0.7 GeV) at Hiroshima Synchrotron Radiation Center (HiSOR). All optical devices of the spectrophotometer were set up under a high vacuum (10-6 Torr), to avoid the absorption of light by air and water vapor. The SR light is separated into two orthogonal linearly polarized light beams by a linear polarizer and then modulated to circularly polarized light at 50 kHz by a photo-elastic modulator (PEM). In order to control PEM accurately and to stabilize the lock-in amplifier under a high vacuum, we used the optical servo-control system. Also, an assembled-type MgF2 cell with a temperature-control unit was constructed using a Peltier thermoelectric element. Its path length can be adjusted by various Tefron spacers in the range from 1.3 to 50 μm and its temperature can be controlled within an accuracy of ± 1 deg C in the range from -30 to 70 deg C. The performance of the spectrophotometer and MgF2 cell constructed was tested by monitoring the CD spectra of ammonium d-camphor-10-sulfonate (ACS), D- and L-isomers of amino acids. These obtained results demonstrate that the optical system and the sample cell constructed normally operate under a high vacuum to provide useful information on the structure analysis of

  14. Multiphoton ionization of CF3I clusters by ultraviolet laser radiation

    International Nuclear Information System (INIS)

    The results of the investigation of the multiphoton ionization of (CF3I)n clusters by ultraviolet laser radiation are reported. The yields of the I2+ and I+ ions, which are the products of the multiphoton ionization, have been measured as functions of the intensity of the ultraviolet radiation at the wavelengths of 308 and 232.5 nm. The degree of multiphoton ionization has been determined and appears to depend on the wavelength of radiation. The velocity distributions of the products have been measured in detail for various wavelengths and various polarizations of radiation. The anisotropy parameters of the velocity distributions of the produced ions and their kinetic energy have been determined. After analysis of the data, a mechanism of the multiphoton ultraviolet ionization of the clusters under investigation has been proposed. This mechanism depends on the used wavelengths.

  15. A new facility for the synchrotron radiation-based calibration of transfer radiation sources in the ultraviolet and vacuum ultraviolet spectral range

    Energy Technology Data Exchange (ETDEWEB)

    Thornagel, Reiner; Fliegauf, Rolf; Klein, Roman, E-mail: roman.klein@ptb.de; Kroth, Simone; Paustian, Wolfgang; Richter, Mathias [Physikalisch-Technische Bundesanstalt (PTB), Berlin (Germany)

    2015-01-15

    The Physikalisch-Technische Bundesanstalt (PTB) has a long tradition in the calibration of radiation sources in the ultraviolet and vacuum ultraviolet spectral range, with traceability to calculable synchrotron radiation. Within this context, new instrumentation in the PTB laboratory at the Metrology Light Source (MLS) has been put into operation that opens up extended and improved calibration possibilities. A new facility for radiation source calibrations has been set up in the spectral range from 7 nm to 400 nm based on a combined normal incidence-grazing incidence monochromator. The facility can be used for the calibration of transfer sources in terms of spectral radiant intensity or mean spectral radiance, with traceability to the MLS primary source standard. We describe the design and performance of the experimental station and give examples of some commissioning results.

  16. Quantifying the effects of corn growth and physiological responses to Ultraviolet-B radiation for modeling

    Science.gov (United States)

    To understand the consequences of rising levels of Ultraviolet-B (UV-B) radiation on maize (Zea mays L.), two experiments were conducted using sunlit plant growth chambers at a wide range UV-B radiation. Maize cultivars Terral-2100 and DKC 65-44 were grown in 2003 and 2008, respectively, at four le...

  17. Effects of antibiotics and ultraviolet radiation on the halophilic blue-green alga

    International Nuclear Information System (INIS)

    The effects of a variety of antibiotics, ultraviolet radiation and N-methyl-N-nitro-N-nitro-N-nitrosoguanidine (NTG) on the survival and mutability of the halophilic blue-green alga, Aphanothece halophytica, were determined. The halophile was found extremely sensitive to penicillin G and bacitracin; moderately sensitive to novobiocin, amino acid analogs, chloramphenicol and streptomycin; and tolerant to actidione and hydroxyurea. Ultraviolet and NTG killing curves and photoreactivation capabilities were seimilar to those reported for other members of the Chroococcales. Three stable morphological mutants were obtained by ultraviolet and NTG treatment, the latter being much more efficient in the production of mutants. (orig.)

  18. Plant spore walls as a record of long-term changes in ultraviolet-B radiation

    Science.gov (United States)

    Lomax, Barry H.; Fraser, Wesley T.; Sephton, Mark A.; Callaghan, Terry V.; Self, Stephen; Harfoot, Michael; Pyle, John A.; Wellman, Charles H.; Beerling, David J.

    2008-09-01

    Stratospheric ozone screens the Earth's surface from harmful ultraviolet-B radiation. Concentrations of stratospheric ozone are governed by a variety of natural and anthropogenic factors, including solar cycles, volcanic aerosols, ozone-depleting substances and climate change. However, assessing this variability before instrumental records has proved difficult owing to the lack of a well-constrained proxy. Here, we use microspectroscopy to analyse the chemical composition of herbarium samples of clubmoss (Lycophyta) spores originating from high- and low-latitude localities, where they were exposed to different ultraviolet-B histories. We show that the concentration of two ultraviolet-B-absorbing compounds in the walls of high-northern- and southern-latitude spores is strongly regulated by historical variations in ultraviolet-B radiation. Conversely, we find little change in the concentration of these compounds in spores originating from tropical Ecuador, where ultraviolet levels have remained relatively stable. Using spores from Greenland, we reconstruct past (1907-1993) changes in ozone concentration and ultraviolet-B flux; we reveal strong similarities between spore-wall reconstructions, and independent instrumental records and model results. Our findings suggest that ultraviolet-B-absorbing compounds in plant spore walls have the potential to act as a proxy for past changes in terrestrial ultraviolet-B radiation and stratospheric ozone. The chemical signature of plant spore walls in herbaria, and possibly also in sedimentary and ice-core archives, may therefore prove valuable for reconstructing past variations in stratospheric ozone and their connections with changes in solar radiation and climate.

  19. Thermoluminescence of LiF:Mg, Cu inducted by ultraviolet radiation

    International Nuclear Information System (INIS)

    The ultraviolet radiation effects in the thermoluminescence of 14 samples doped with LiF in differents concentrations of Mg and Cu impurities are analyzed. The thermoluminescent sensitivity to ultraviolet light increases with the increase of magnesium impurity concentration to the 0,4 mol% and for the copper, the sensitivity reachs the maximum concentration at 0,06 mol%, for decrease in the 0,12 mol%. (C.G.C.)

  20. Accelerated induction of skin cancers by ultraviolet radiation in hairless mice treated with immunosuppressive agents

    International Nuclear Information System (INIS)

    An increased incidence of cancer is well recognized in organ transplant recipients treated with immunosuppressive agents. Skin cancers are the most common lesions encountered. To investigate a possible relationship between the immunosuppressive agents and ultraviolet radiation (UVR), several groups of hairless mice were treated with ultraviolet light, azathioprine, or prednisone, or the three in various combination. The two latter drugs are the immunosuppressive agents most frequently used in organ transplant recipients

  1. Accelerated induction of skin cancers by ultraviolet radiation in hairless mice treated with immunosuppressive agents

    Energy Technology Data Exchange (ETDEWEB)

    Koranda, F.C.; Loeffler, R.T.; Koranda, D.M.; Penn, I.

    1975-01-01

    An increased incidence of cancer is well recognized in organ transplant recipients treated with immunosuppressive agents. Skin cancers are the most common lesions encountered. To investigate a possible relationship between the immunosuppressive agents and ultraviolet radiation (UVR), several groups of hairless mice were treated with ultraviolet light, azathioprine, or prednisone, or the three in various combination. The two latter drugs are the immunosuppressive agents most frequently used in organ transplant recipients.

  2. Sensitivity of the vibrios to ultraviolet-radiation

    International Nuclear Information System (INIS)

    The ultraviolet-inactivation kinetics of a number of strains of Vibrio cholerae (classical), Vibrio cholerae (el tor), NAG vibrios and Vibrio parahaemolyticus were investigated. Statistical analyses revealed significant differences between any two of the four types of vibrio in respect of their sensitivity to U.V. (author)

  3. Low doses of ultraviolet-B or ultraviolet-C radiation affect phytohormones in young pea plants

    International Nuclear Information System (INIS)

    Pea (cv. Scinado) seedlings were exposed to low doses of ultraviolet-B (UV-B; 4.4 and 13.3 kJ/square m/d) or UV-C (0.1 and 0.3 kJ/square m/d) radiation for 14 d. Aminocyclopropane carboxylic acid (ACC), indoleacetic acid (IAA) and abscisic acid (ABA) concentrations were quantified by gas chromatography coupled to mass spectrometry. The accumulation of ACC upon irradiation was dose-dependent. ABA conc. was reduced and IAA conc. increased upon UV-C treatment, whereas the UV-B doses used did not cause significant changes in ABA and IAA levels

  4. An integrated artificial neural networks approach for predicting global radiation

    International Nuclear Information System (INIS)

    This article presents an integrated artificial neural network (ANN) approach for predicting solar global radiation by climatological variables. The integrated ANN trains and tests data with multi layer perceptron (MLP) approach which has the lowest mean absolute percentage error (MAPE). The proposed approach is particularly useful for locations where no available measurement equipment. Also, it considers all related climatological and meteorological parameters as input variables. To show the applicability and superiority of the integrated ANN approach, monthly data were collected for 6 years (1995-2000) in six nominal cities in Iran. Separate model for each city is considered and the quantity of solar global radiation in each city is calculated. Furthermore an integrated ANN model has been introduced for prediction of solar global radiation. The acquired results of the integrated model have shown high accuracy of about 94%. The results of the integrated model have been compared with traditional angstrom's model to show its considerable accuracy. Therefore, the proposed approach can be used as an efficient tool for prediction of solar radiation in the remote and rural locations with no direct measurement equipment.

  5. Ultraviolet radiation (UVR) (290-400 nm) radiometry of solar simulation for experimental radiation in drug and chemical photosensitization

    Science.gov (United States)

    Young, A. R.; Magnus, I. A.; Gibbs, N. K.

    1982-02-01

    The ultraviolet radiation (UVR) radiometry of solar simulated radiation in a long-term photocarcinogenesis project is described. The methods used were (a) a phototherapy radiometer, (b) an electronic integrating dosimeter, (c) indirect spectroradiometry,and (d) polysulphone and naladixic film badge dosimeters for UV-B (280-315 nm) and UV-A (315-400 nm) radiation, respectively. The merits of the various methods are discussed. The importance of reliable and practical UVR radiometry is emphasised.

  6. Effect of ultraviolet radiation absorbing film on pollination work of foreign bumblebee [Bombus terrestris

    International Nuclear Information System (INIS)

    The transmitted light through the ultraviolet radiation absorbing (UVA) film has a preventing effect of disease and pest occurrence. To develop the agriculture harmonized with the ecosystem, we attempted to research a further possible utilization of the UVA film. Pollination work of foreign bumblebee (Bombus terrestris) in the greenhouses roofed with UVA film and with common film for agriculture was examined in growing fruit-vegetables. The bumblebees used were not acclimatized to environmental conditions of the greenhouses. They visited flowers and gathered pollen from flowered crops grown in both houses, irrespective of the kind of film covering over the greenhouse roof, and the pollen quantity gathered was far greater in crops which produced in large quantity of pollen. Thus, the bumblebees were capable to work under the condition lacking in ultraviolet radiation. This pollinating behavior is different from that of honeybees. Then we concluded that bumblebees functioned well as an efficient pollinator under the condition without ultraviolet radiation

  7. Knowledge about Ultraviolet Radiation Hazards and Tanning Behavior of Cosmetology and Medical Students.

    Science.gov (United States)

    Zuba, Ewelina Bogumiła; Francuzik, Wojciech; Malicki, Przemysław; Osmola-Mańkowska, Agnieszka; Jenerowicz, Dorota

    2016-04-01

    Dear Editor, Ultraviolet (UV) radiation is a well-known physical hazard responsible for photoaging, photoallergic, and phototoxic reactions as well as carcinogenesis, including life-threatening melanomas (1,2). Overexposure to both natural and artificial UV radiation is a public health concern. 30% of cancers diagnosed worldwide are skin cancers. Approximately three million non-melanoma skin cancers and 132 000 new cases of melanomas are diagnosed globally each year (3). Sunburns, especially in childhood, are a very important risk factor for melanomas. Several studies demonstrated a positive association between sunbed use and an increased incidence of malignant melanoma (4). Current medical and cosmetology students will soon be knowledge providers about the risks of excessive exposure to UV radiation and prophylaxis of its consequences. Our aim was to evaluate their knowledge about the side effects of ultraviolet radiation and tanning behaviors. Details on the knowledge and habits of students were obtained during classes at the Poznan University of Medical Sciences. With approval from the Institutional Bioethical Committee, a 41-question anonymous survey was conducted in the spring of 2012 among 190 medical (1-6 year) and cosmetology students (1-5 year). The mean age of the study group was 22.3 years (standard deviation (SD) = 2.4 years), range 19-28 years. The survey was composed of closed and open-ended questions prepared by the authors. The first part of the form included demographic data: gender, age, degree course, and school year. The students were also asked about their reaction to sunlight, sunburns in childhood, and personal and family history of skin cancers or dysplastic nevus syndrome. The factual section of the survey contained questions evaluating responder knowledge about sunbeds and risk of UV radiation as well as their personal tanning habits. The open-ended questions asked responders to provide definitions of: skin phototype, sun protection factor

  8. Luminescent glass fiber sensors for ultraviolet radiation detection by the spectral conversion

    Science.gov (United States)

    Agafonova, Darina S.; Kolobkova, Elena V.; Ignatiev, Alexander I.; Nikonorov, Nikolay V.; Shakhverdov, Teimur A.; Shirshnev, Pavel S.; Sidorov, Alexander I.; Vasiliev, Vladimir N.

    2015-11-01

    It is shown that glass fibers doped with luminescent molecular clusters of silver, cadmium and lead chalcogenides, or copper (I) can be used for the efficient radiation conversion of ultraviolet (UV) radiation to the visible spectral region. The advantages of radiation trapping in fibers by the luminescent centers and of spectral conversion are discussed. The excitation and luminescence spectra of luminescent fibers are presented. Analysis of application areas of the luminescent glasses and fibers is performed. The construction of the sensitive element for sensor models for electrical spark and UV radiation detection is described. The characteristics of the models of sensors for electrical spark and UV radiation detection are presented.

  9. Effect of ultraviolet radiation on eicosanoid metabolism of cells in culture

    International Nuclear Information System (INIS)

    The mechanisms by which ultraviolet radiation induces alteration of various functions of human skin are poorly understood. Such radiation is known to have profound effects on the nuclear material of the cells of cutaneous organ. These effects have been carefully studied utilizing cells in culture as model systems. Only recently have these systems been utilized to study the effect of radiant energy on membrane metabolism of cells. These early studies, summarized briefly in this communication, indicate that ultraviolet radiation is capable of inducing the deacylation of arachidonic acid from the membrane phospholipids of a number of different types of mammalian cells. This decylation can occur from irradiation of cells with energy from light sources emitting photons across the entire spectrum (UVA, UVB, and UVC). The arachidonic acid released can then be metabolized via both cyclooxygenase and lipoxygenase pathways to form many different eicosanoids, dependent on cell type. This effect on eicosanoid metabolism is induced with biologically relevant quantities of ultraviolet radiation and can be induced with UV alone or with IV and chemical photosensitizer. Solar ultraviolet radiation (UV) is a ubiquitous environmental agent known to produce numerous effects in human skin. These effects include inflammation, pigmentation, carcinogenesis, local and systemic immune suppression, aging and Vitamin D metabolism

  10. Spontaneous and artificial direct nanostructuring of solid surface by extreme ultraviolet laser with nanosecond pulses

    Czech Academy of Sciences Publication Activity Database

    Koláček, Karel; Schmidt, Jiří; Štraus, Jaroslav; Frolov, Oleksandr; Prukner, Václav; Melich, Radek; Psota, Pavel

    2016-01-01

    Roč. 34, č. 1 (2016), s. 11-22. ISSN 0263-0346 Institutional support: RVO:61389021 Keywords : Extreme ultraviolet (XUV) interferometer * Aspheric interferometer mirrors * Multilayer reflection coating for 46.9 nm * Ar8+ laser application * XUV direct nanostructuring Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.295, year: 2014 http://dx.doi.org/10.1017/S0263034615000786

  11. Acute Ultraviolet Radiation Perturbs Epithelialization but not the Biomechanical Strength of Full-thickness Cutaneous Wounds

    DEFF Research Database (Denmark)

    Danielsen, Patricia L; Lerche, Catharina M; Wulf, Hans Christian;

    2016-01-01

    We hypothesized that priming of the skin with ultraviolet radiation (UVR) before being injured would enhance wound healing. Four groups, each comprising 20 immunocompetent hairless mice, were exposed to simulated solar irradiation in escalating UVR doses; 0 standard erythema dose (SED) = control,...

  12. Wavelength-dependent xanthophyll cycle activity in marine microalgae exposed to natural ultraviolet radiation

    NARCIS (Netherlands)

    Buma, Anita G. J.; Visser, Ronald J. W.; Van De Poll, Willem H.; Villafane, Virginia E.; Janknegt, Paul J.; Walter Helbling, E.

    2009-01-01

    The wavelength dependency of xanthophyll cycling in two marine microalgae (Thalassiosira weissflogii and Dunaliella tertiolecta) was studied by establishing biological weighting functions (BWFs) during exposure to natural ultraviolet radiation. High-(HL) and low-(LL) light-acclimated cultures of bot

  13. Acclimation of brown algal photosynthesis to ultraviolet radiation in Arctic coastal waters (Spitsbergen, Norway)

    NARCIS (Netherlands)

    Bischof, K.; Hanelt, D.; Tug, H.; Karsten, U.; Brouwer, P.E.M.; Wiencke, C.

    1998-01-01

    In field studies conducted at the Kongsfjord (Spitsbergen) changes of the irradiance in the atmosphere and the sublittoral zone were monitored from the beginning of June until the end of August 1997, to register the minimum and maximum fluxes of ultraviolet and photosynthetically active radiation an

  14. Investigation of Low-Pressure Ultraviolet Radiation on Inactivation of Rhabitidae Nematode from Water

    Directory of Open Access Journals (Sweden)

    Mohammad Hadi Dehghani

    2013-03-01

    Full Text Available Background: Rhabditidae is a family of free-living nematodes. Free living nematodes due to their active movement and resistance to chlorination, do not remove in conventional water treatment processes thus can be entered to distribution systems and cause adverse health effects. Ultraviolet radiation (UV can be used as a method of inactivating for these organisms. This cross sectional study was done to investigate the efficiency of ultraviolet lamp in the inactivation of free living nematode in water.Methods: The effects of radation time, turbidity, pH and temperature were invistigated in this study. Ultraviolet lamp used in this study was a 11 W lamp and intensity of this lamp was 24 µw / cm2.Results: Radiation time required to achieve 100% efficiency for larvae nematode and adults was 9 and 10 minutes respectively. There was a significant correlation between the increase in radiation time, temperature rise and turbidity reduction with inactivation efficiency of lamp (P<0.001. Increase of turbidity up 25 NTU decreased inactivation efficiency of larvae and adult nematodes from 100% to 66% and 100% to 64% respectively. Change in pH range from 6 to 9 did not affect the efficiency of inactivation. With increasing temperature inactivation rate increased. Also the effect of the lamp on inactivation of larvae nematod was mor than adults.Conclusions: It seems that with requiring the favorable conditions low-pressure ultraviolet radiation systems can be used for disinfection of water containing Rhabitidae nematode.

  15. Soft X-rays and extreme ultraviolet radiation principles and applications

    CERN Document Server

    Attwood, David

    1999-01-01

    This self-contained, comprehensive book describes the fundamental properties of soft X-rays and extreme ultraviolet (EUV) radiation and discusses their applications in a wide variety of fields, including EUV lithography for semiconductor chip manufacture and soft X-ray biomicroscopy. The book will be of great interest to graduate students, researchers and practising engineers.

  16. Tea, coffee, and cocoa as ultraviolet radiation protectants for beet armyworm nucleopolyhedrovirus

    Science.gov (United States)

    The addition of 1% (wt/v) aqueous extracts of cocoa (Theobroma cacao L.) (Malvales: Malvaceae), coffee (Coffea arabica L.) (Gentianales: Rubiaceae), green, and black tea (Camellia sinensis L.) (Ericales: Theaceae) provided excellent ultraviolet (UV) radiation protection for the beet armyworm, Spodo...

  17. Decreased risk of prostate cancer after skin cancer diagnosis: A protective role of ultraviolet radiation?

    NARCIS (Netherlands)

    E. de Vries (Esther); I. Soerjomataram (Isabelle); S. Houterman (Saskia); M.W.J. Louwman (Marieke); J.W.W. Coebergh (Jan Willem)

    2007-01-01

    textabstractUltraviolet radiation causes skin cancer but may protect against prostate cancer. The authors hypothesized that skin cancer patients had a lower prostate cancer incidence than the general population. In the southeastern part of the Netherlands, a population-based cohort of male skin canc

  18. Evaluation of a low-intensity ultraviolet-C radiation device for decontamination of computer keyboards.

    Science.gov (United States)

    Shaikh, Aaron A; Ely, Dylan; Cadnum, Jennifer L; Koganti, Sreelatha; Alhmidi, Heba; Sankar C, Thriveen; Jencson, Annette L; Kundrapu, Sirisha; Donskey, Curtis J

    2016-06-01

    Computer keyboards are a potential source for dissemination of pathogenic microorganisms. We demonstrated that a low-intensity ultraviolet-C (UV-C) radiation device was effective in reducing methicillin-resistant Staphylococcus aureus, carbapenem-resistant Escherichia coli, and Clostridium difficile spores on steel carriers and significantly reduced bacterial counts on in-use keyboards. PMID:26781219

  19. Evaluation of an enclosed ultraviolet-C radiation device for decontamination of mobile handheld devices.

    Science.gov (United States)

    Mathew, J Itty; Cadnum, Jennifer L; Sankar, Thriveen; Jencson, Annette L; Kundrapu, Sirisha; Donskey, Curtis J

    2016-06-01

    Mobile handheld devices used in health care settings may become contaminated with health care-associated pathogens. We demonstrated that an enclosed ultraviolet-C radiation device was effective in rapidly reducing methicillin-resistant Staphylococcus aureus, and with longer exposure times, Clostridium difficile spores, on glass slides and reducing contamination on in-use mobile handheld devices. PMID:26921014

  20. Sensitivity of Escherichia coli acrA Mutants to Psoralen plus Near-Ultraviolet Radiation

    DEFF Research Database (Denmark)

    Hansen, M. Trier

    1982-01-01

    The sensitivity to psoralen plus near-ultraviolet radiation (PUVA) was compared in a pair of E. coli strains differing at the acrA locus. Survival was determined for both bacteria and phage λ. AcrA mutant cells were 40 times more sensitive than wild type to the lethal effect of PUVA. Free λ phage...

  1. Stimulated luminescence of AlN ceramics induced by ultraviolet radiation

    DEFF Research Database (Denmark)

    Trinkler, L.; Bøtter-Jensen, L.; Christensen, P.;

    2001-01-01

    Properties of thermally stimulated luminescence (TL) and optically stimulated luminescence (OSL) of the ceramic material A1N-Y2O3 have been studied after exposure to ultraviolet radiation (UVR). The dosemeter material Al2O3 : C has been used for comparative measurements. The spectral sensitivity of...

  2. Solar ultraviolet radiation in Australia. Results from network measurements and their use in public education

    International Nuclear Information System (INIS)

    Growing evidence of global depletion of stratospheric ozone has given additional support to the ultraviolet radiation (UVR) network established by ARL in Australia and Antarctica. The data produced is necessary to increase our knowledge of atmospheric change, human health studies and for public education. (4 figs., 1 tab.)

  3. Latitude gradients for lymphoid neoplasm subtypes in Australia support an association with ultraviolet radiation exposure.

    Science.gov (United States)

    van Leeuwen, Marina T; Turner, Jennifer J; Falster, Michael O; Meagher, Nicola S; Joske, David J; Grulich, Andrew E; Giles, Graham G; Vajdic, Claire M

    2013-08-15

    Given the uncertainty surrounding solar ultraviolet radiation (UVR) exposure and risk of lymphoid neoplasms, we performed an ecological analysis of national Australian data for incident cases diagnosed between 2002 and 2006. Subtype-specific incidence was examined by latitude band (vitamin D-related immune modulation critical in lymphomagenesis. PMID:23382012

  4. Determinants of personal ultraviolet-radiation exposure doses on a sun holiday

    DEFF Research Database (Denmark)

    Petersen, B; Thieden, E; Philipsen, P A;

    2013-01-01

    A great number of journeys to sunny destinations are sold to the Danish population every year. We suspect that this travel considerably increases personal annual ultraviolet-radiation (UVR) exposure doses. This is important because such exposure is the main cause of skin cancer, and studies have...... shown a correlation between intermittent solar UVR exposure and malignant melanoma....

  5. Ultraviolet radiation after exposure to a low-fluence IPL home-use device

    DEFF Research Database (Denmark)

    Thaysen-Petersen, Daniel; Erlendsson, Andres M; Nash, J F;

    2015-01-01

    The prevailing advice is to avoid sun exposure after intense pulsed light (IPL) hair removal. However, no systematic evaluation of ultraviolet radiation (UVR) after IPL hair removal exits. Therefore, we investigated the occurrence of side effects in subjects receiving solar-simulated UVR after a...

  6. Surface Daytime Net Radiation Estimation Using Artificial Neural Networks

    Directory of Open Access Journals (Sweden)

    Bo Jiang

    2014-11-01

    Full Text Available Net all-wave surface radiation (Rn is one of the most important fundamental parameters in various applications. However, conventional Rn measurements are difficult to collect because of the high cost and ongoing maintenance of recording instruments. Therefore, various empirical Rn estimation models have been developed. This study presents the results of two artificial neural network (ANN models (general regression neural networks (GRNN and Neuroet to estimate Rn globally from multi-source data, including remotely sensed products, surface measurements, and meteorological reanalysis products. Rn estimates provided by the two ANNs were tested against in-situ radiation measurements obtained from 251 global sites between 1991–2010 both in global mode (all data were used to fit the models and in conditional mode (the data were divided into four subsets and the models were fitted separately. Based on the results obtained from extensive experiments, it has been proved that the two ANNs were superior to linear-based empirical models in both global and conditional modes and that the GRNN performed better and was more stable than Neuroet. The GRNN estimates had a determination coefficient (R2 of 0.92, a root mean square error (RMSE of 34.27 W∙m−2, and a bias of −0.61 W∙m−2 in global mode based on the validation dataset. This study concluded that ANN methods are a potentially powerful tool for global Rn estimation.

  7. Enhancements in biologically effective ultraviolet radiation following volcanic eruptions

    Science.gov (United States)

    Vogelmann, A. M.; Ackerman, T. P.; Turco, R. P.

    1992-01-01

    A radiative transfer model is used to estimate the changes in biologically effective radiation (UV-BE) at the earth's surface produced by the El Chichon (1982) and Mount Pinatubo (1991) eruptions. It is found that in both cases surface intensity can increase because the effect of ozone depletion outweighs the increased scattering.

  8. Interactive effects of ultraviolet and photosynthetically active radiation on photosynthesis, growth, and photoprotective mechanisms

    Czech Academy of Sciences Publication Activity Database

    Klem, Karel; Urban, Otmar

    Volume 1. 1. Brno: Global Change Research Centre, Academy of Sciences of the Czech Republic, v. v. i, 2015 - (Urban, O.; Klem, K.), s. 99-112 ISBN 978-80-87902-14-1 R&D Projects: GA MŠk(CZ) LO1415 Institutional support: RVO:67179843 Keywords : ultraviolet radiation * photosynthetically active radiation * photoprotection * flavonols * xanthophyl-cycle pigments * barley * photosynthesis Subject RIV: EH - Ecology, Behaviour

  9. Calibration technique for radiation measurements in vacuum ultraviolet - soft x-ray region

    International Nuclear Information System (INIS)

    This is a collection of the papers presented at the workshop on ''Calibration Technique for Radiation Measurements in Vacuum Ultraviolet - Soft X-ray Region'' held at the Institute of Plasma Physics, Nagoya University, on December 19 - 20, 1985, under the Collaborating Research Program at the Institute. The following topics were discussed at the workshop: the needs for the calibration of plasma diagnostic devices, present status of the calibration technique, use of the Synchrotron Orbit Radiations for radiometry, and others. (author)

  10. On measurements and modeling of ultraviolet radiation with focus on the Antarctic

    OpenAIRE

    Meinander, Outi

    2007-01-01

    The aim of the work was to study, on the basis of literature and experiments, the aspects of measuring and modeling ultraviolet radiation. For measurements, both the spectral and the non-spectral approaches were included. For modeling, physical and statistical models were applied. Thereafter the satellite UV estimates, i.e. spaceborn spectrometer measurements on solar radiation combined with physical UV modeling, were shortly introduced. Case studies were carried out for each of the five case...

  11. An Immunohistochemical Panel to Assess Ultraviolet Radiation Associated Oxidative Skin Injury

    OpenAIRE

    Mamalis, A; Fiadorchanka, N; L. ADAMS; Serravallo, M; Heilman, E; Siegel, D; Brody, N; Jagdeo, J

    2014-01-01

    Ultraviolet (UV) radiation results in a significant loss in years of healthy life, approximately 1.5 million disability-adjusted life years, and is associated with greater than 60,000 deaths annually worldwide that are attributed to melanoma and other skin cancers. Currently, there are no standardized biomarkers or assay panels to assess oxidative stress skin injury patterns in human skin exposed to ionizing radiation. Using biopsy specimens from chronic solar UV-exposed and UV-protected skin...

  12. Effect of ultraviolet radiation on laboratory cultures of green algae and cyanobacteria

    International Nuclear Information System (INIS)

    Since the discovery of the ozone hole, an increasing amount of work has been devoted to measuring the impact of the UV-radiation on living organisms. In this point of view, algae as the primer producers of aquatic ecosystems, get to the central part of the interest. The aim of the study was to study the effect of ultraviolet radiation on laboratory cultures of green algae and cyanobacteria

  13. EFFECT OF ORGANIC TURMERIC (Curcuma longa) FEEDING ON TESTICULAR HISTOLOGY OF RABBITS EXPOSED TO ULTRAVIOLET RADIATION

    OpenAIRE

    Togun, V.A.; Amao, O.A.; Adebisi, J.A.; Okwusidi, J.I.; Williams, O. S.

    2014-01-01

    Thirty six male rabbits of 450-600g weight range fed with mostly organic ingredient feed, were weight-balanced into six treatment groups that received rabbit diets either without (D1) or with organic turmeric (D2) at varying periods within a nine- week experimental period. The treatments were T0, T1, T2, T3, T4 and T5 for control, D2 plus exposure to Ultraviolet (UV) radiation, D2 until radiation, D2 after radiation, D1 throughout the experimental period with UV radiation and D2 throughout th...

  14. Ultraviolet radiation effects on pigmentation in the cyanobacterium ''Phormidium uncinatum''

    International Nuclear Information System (INIS)

    The Baikal strain of the cyanobacterium Phormidium uncinatum was found to possess the photosynthetic pigments chlorophyll a, carotenoids, phycocyanin and allophycocyanin, while the Tuebingen strain of Phormidium contained, in addition to these, the biliprotein phycoerythrin. Sucrose gradient centrifugation of the pigment extracts resulted in a separation of the phycobiliproteins into several bands, which according to their absorption and fluorescence properties, were identified as monomers, trimers and hexamers. With increasing UV-B irradiation the heavier aggregates were broken down into smaller components. Photobleaching of these accessory pigments also occurred. FPLC gel filtration analyses of the pigments also showed loss of heavier aggregates of the phycobilins and bleaching of the pigments. SDS-polyacrylamide gel electrophoresis of the sucrose gradient and FPLC fractions indicated loss of the biliproteins with increasing UV-B irradiation. The loss of the β- were more rapid than that of the α- subunits. Increasing levels of ultraviolet irradiation is therefore deleterious to these organism. (author)

  15. Ultraviolet radiation effects on pigmentation in the cyanobacterium ``Phormidium uncinatum``

    Energy Technology Data Exchange (ETDEWEB)

    Donkor, V.A.; Haeder, D.P. [Inst. fuer Botanik und Pharmaceutische Biologie, Friedrich-Alexander-Universitaet, Erlangen (Germany)

    1997-12-31

    The Baikal strain of the cyanobacterium Phormidium uncinatum was found to possess the photosynthetic pigments chlorophyll a, carotenoids, phycocyanin and allophycocyanin, while the Tuebingen strain of Phormidium contained, in addition to these, the biliprotein phycoerythrin. Sucrose gradient centrifugation of the pigment extracts resulted in a separation of the phycobiliproteins into several bands, which according to their absorption and fluorescence properties, were identified as monomers, trimers and hexamers. With increasing UV-B irradiation the heavier aggregates were broken down into smaller components. Photobleaching of these accessory pigments also occurred. FPLC gel filtration analyses of the pigments also showed loss of heavier aggregates of the phycobilins and bleaching of the pigments. SDS-polyacrylamide gel electrophoresis of the sucrose gradient and FPLC fractions indicated loss of the biliproteins with increasing UV-B irradiation. The loss of the {beta}- were more rapid than that of the {alpha}- subunits. Increasing levels of ultraviolet irradiation is therefore deleterious to these organism. (author). 41 refs, 7 figs.

  16. Accelerated larvae development of Ascaris lumbricoides eggs with ultraviolet radiation

    International Nuclear Information System (INIS)

    In order to investigate the effect of UV radiation on the development of Ascaris lumbricoides larvae, eggs were exposed to increasing UV doses. Filtered wastewater from the secondary effluent taken from the Damascus wastewater treatment plant (DWTP) was used as irradiation and incubation medium. The progressive and accelerated embryonation stages were microscopically observed and the percentages of completely developed larvae were determined weekly. Results indicated that the UV radiation accelerated the development of larvae with increasing UV dose. Preliminary information about the relationship between the UV radiation dose and rate of embryonation is also presented

  17. Accelerated larvae development of Ascaris lumbricoides eggs with ultraviolet radiation

    Science.gov (United States)

    Aladawi, M. A.; Albarodi, H.; Hammoudeh, A.; Shamma, M.; Sharabi, N.

    2006-01-01

    In order to investigate the effect of UV radiation on the development of Ascaris lumbricoides larvae, eggs were exposed to increasing UV doses. Filtered wastewater from the secondary effluent taken from the Damascus wastewater treatment plant (DWTP) was used as irradiation and incubation medium. The progressive and accelerated embryonation stages were microscopically observed and the percentages of completely developed larvae were determined weekly. Results indicated that the UV radiation accelerated the development of larvae with increasing UV dose. Preliminary information about the relationship between the UV radiation dose and rate of embryonation is also presented.

  18. Accelerated larvae development of Ascaris lumbricoides eggs with ultraviolet radiation

    Energy Technology Data Exchange (ETDEWEB)

    Aladawi, M.A. [Syrian Atomic Energy Commission, Radiation Technology Department, P.O. Box 6091, Damascus (Syrian Arab Republic)]. E-mail: Scientific@aec.org.sy; Albarodi, H. [Syrian Atomic Energy Commission, Radiation Technology Department, P.O. Box 6091, Damascus (Syrian Arab Republic); Hammoudeh, A. [Syrian Atomic Energy Commission, Radiation Technology Department, P.O. Box 6091, Damascus (Syrian Arab Republic); Shamma, M. [Syrian Atomic Energy Commission, Radiation Technology Department, P.O. Box 6091, Damascus (Syrian Arab Republic); Sharabi, N. [Syrian Atomic Energy Commission, Radiation Technology Department, P.O. Box 6091, Damascus (Syrian Arab Republic)

    2006-01-15

    In order to investigate the effect of UV radiation on the development of Ascaris lumbricoides larvae, eggs were exposed to increasing UV doses. Filtered wastewater from the secondary effluent taken from the Damascus wastewater treatment plant (DWTP) was used as irradiation and incubation medium. The progressive and accelerated embryonation stages were microscopically observed and the percentages of completely developed larvae were determined weekly. Results indicated that the UV radiation accelerated the development of larvae with increasing UV dose. Preliminary information about the relationship between the UV radiation dose and rate of embryonation is also presented.

  19. Radiative lifetimes in B I using ultraviolet and vacuum-ultraviolet laser-induced fluorescence

    Science.gov (United States)

    O'Brian, T. R.; Lawler, J. E.

    1992-01-01

    Radiative lifetimes of the eight lowest even parity levels in the doublet system of B I are measured using time-resolved laser-induced fluorescence in the UV and VUV on an atomic beam of boron. The accurate lifetimes provide a base for improved determination of absolute transition probabilities in B I. The techniques described are broadly applicable to measurement of lifetimes of levels with transitions in the visible, UV, and VUV in almost any element.

  20. Changes in biologically active ultraviolet radiation reaching the Earth's surface

    OpenAIRE

    McKenzie, Richard L.; Björn, Lars Olof; Bais, Alkiviadis; Ilyasd, Mohammad

    2003-01-01

    Since publication of the 1998 UNEP Assessment, there has been continued rapid expansion of the literature on UV-B radiation. Many measurements have demonstrated the inverse relationship between column ozone amount and UV radiation, and in a few cases long-term increases due to ozone decreases have been identified. The quantity, quality and availability of ground-based UV measurements relevant to assessing the environmental impacts of ozone changes continue to improve. Recent studies have cont...

  1. Phytochemicals for prevention of solar ultraviolet radiation-induced damages.

    Science.gov (United States)

    Adhami, Vaqar M; Syed, Deeba N; Khan, Naghma; Afaq, Farrukh

    2008-01-01

    While solar light is indispensable for sustenance of life, excessive exposure can cause several skin-related disorders. The UV part of solar radiation, in particular, is linked to disorders ranging from mild inflammatory effects of the skin to as serious as causing several different types of cancers. Changes in lifestyle together with depletion in the atmospheric ozone layer during the last few decades have led to an increase in the incidence of skin cancer. Skin cancers consisting of basal and squamous cell carcinomas are especially linked to the UVB part of solar radiation. Reducing excessive exposure to solar radiation is desirable; however, as this approach is unavoidable, it is suggested that other novel strategies be developed to reduce the effects of solar radiation to skin. One approach to reduce the harmful effects of solar radiation is through the use of phytochemicals, an approach that is popularly known as "Photochemoprotection." In recent years many phytochemicals with potential antioxidant properties have been identified and found to be photoprotective in nature. We describe here some of the most popular phytochemicals being studied that have the potential to reduce the harmful effects associated with solar UV radiation. PMID:18266816

  2. Exposure to ultraviolet-B radiation increases cold hardiness in Rhododendron

    International Nuclear Information System (INIS)

    The change in the cold hardiness of Rhododendron (cv. English Roseum) following chronic exposure to ultraviolet-B (UV-B) radiation (280–320 nm) was studied. Leaf disks removed from UV-B-exposed plants exhibited a greater tolerance to freezing temperatures than plants that received no UV-B exposure. Visual browning and percent phenolic leakage indicated that UV-B-exposed leaf disks were killed al -11°C. while control disks were killed at -8°C. Ultraviolet-induced production of phenolic compounds may be involved in increasing cold hardiness of Rhododendron leaf tissues

  3. Preparation of Modified Poly( ethylene terephthalate) Fibers and Their Properties of Ultraviolet Radiation Protection

    Institute of Scientific and Technical Information of China (English)

    滕翠青; 余木火

    2001-01-01

    Protection against solar ultraviolet radiation (UVR)among the general public has been increasing steadily.Poly( ethylene terephthalate) (PET) was blended with UVR protection agent and was spun into the modified fibers with the properties of UVR protection. An investigation on the properties using an ultraviolet spectrophotometer showed that the modified PET fabrics could be resistant to UVR more than 90% in the band of UV-B. The effect of the heat insulation and the mechanical properties of the fibers were also studied.

  4. Sun's image in the extreme ultraviolet radiation emitted from the corona

    Science.gov (United States)

    1973-01-01

    The Skylab space station's Extreme Ultraviolet monitor is a closed loop television system that permitted man for the first time to watch the Sun's image in the extreme ultraviolet radiation emitted from its million-degree outer atmosphere, the corona. This photograph shows a view of the TV scope made by Scientist-Astronaut Owen K. Garriott, Skylab 3 science pilot, on August 15, 1973. Dr. Garriott made this picture with a Land-Polaroid SX-70 camera - the first time that any Polaroid camera has been used in space.

  5. Kinetics study on photochemical oxidation of polyacrylamide by ozone combined with hydrogen peroxide and ultraviolet radiation

    Institute of Scientific and Technical Information of China (English)

    REN Guang-meng; SUN De-zhi; CHUNG Jong Shik

    2006-01-01

    An investigation on the process of ozone combined with hydrogen peroxide and ultraviolet radiation has been carried out in order to establish the kinetics for photochemical oxidation of polyacrylamide (PAM) in aqueous solution. Effects of operating parameters, including initial PAM concentration, dosages of ozone and hydrogen peroxide, UV radiation and pH value on the photochemical oxidation of PAM, have been studied. There was an increase in photochemical oxidation rate of PAM with increasing of dosages of O3, H2O2 and ultraviolet radiation. Upon increasing of the initial PAM concentration, the photochemical oxidation rate of PAM decreased. Slight effect of pH value on the photochemical oxidation rate of PAM was observed in the experiments. The kinetics equation for the photochemical oxidation of PAM by the system has been established.

  6. Effects of emollients on ultraviolet-radiation-induced erythema of the skin

    International Nuclear Information System (INIS)

    Several commonly used emollients were studied as to their effectiveness in absorbing and filtering erythema-causing ultraviolet radiation in the 280 to 315 nm range (UVB). Planter's Peanut Oil (Standard Brands) and Mazola Corn Oil (Best Foods Inc.) had no effect; Alpha Keri Bath Oil (Westwood Pharmaceuticals), mineral oil, and Johnson's Baby Oil (Johnson and Johnson Co) had minimal effects. Vaseline Petroleum Jelly (Chesebrough-Ponds Inc.), petrolatum, and hydrophilic ointment substantially reduced the erythema that was induced by exposure to low doses of UVB radiation. Therefore, these emollients may interfere with the therapeutic effects of the ultraviolet radiation component of the Goeckerman treatment when it is administered in low doses to patients with psoriasis

  7. Furanocoumarins in wild parsnip: effects of photosynthetically active radiation, ultraviolet light, and nutrients

    International Nuclear Information System (INIS)

    Previous studies of wild parsnip, Pastinaca sativa L., revealed a significant degree of genetically controlled variation in furanocoumarin production. In this study, the influence of environmental factors, namely, soil nutrients, photosynthetically active radiation, and ultraviolet (UV) radiation, on the production of furanocoumarins in the wild parsnip was examined experimentally. Aboveground tissues of plants grown under all combinations of three light intensities and three nutrient levels (N, P, K) were analyzed for the absolute and relative amounts of furanocoumarins. In a second experiment the effect of ultraviolet radiation on furanocoumarin production was evaluated by growing plants under full sunlight with and without an ultraviolet screen. Light and nutrient availability jointly affected the concentration of four of the six furanocoumarins present (sphondin and angelicin being the exceptions). Both nutrients and light were limiting factors in furanocoumarin production insofar as low availability of either resource limited the effect of variation in other resource. Relative amounts of the furanocoumarins were independently influenced by light and nutrient availability. UV radiation increased the concentration of all but two of the furanocoumarins (imperatorin and sphondin) and also influenced that relative amounts of furanocoumarins. Since furanocoumarins are UV-phototoxic to many organisms, including insects, the response of parsnip plants to UV radiation may affect their resistance to herbivores. (author)

  8. Effect of solar ultraviolet radiation on growth in the marine macroalga Dictyota dichotoma (Phaeophyceae) at Helgoland and its ecological consequences

    Science.gov (United States)

    Kuhlenkamp, R.; Franklin, L. A.; Lüning, K.

    2001-03-01

    At Helgoland, in the North Sea, growth of the high sublittoral brown macroalga Dictyota dichotoma (Hudson) Lamoroux was examined in October (the time of tetraspore release) in an outdoor tank by exposing 2-day-old germlings to four solar radiation treatments achieved with different filter materials or an additional artificial light source: photosynthetically active radiation (PAR; 395-700 nm), PAR plus ultraviolet (UV)-A (320-700 nm), full solar spectrum, or solar spectrum plus artificial UV radiation (UVR). Based on length measurements over a period of 3 weeks, the growth rate in germlings strongly decreased in conditions with UVR compared to PAR: by 14% under PAR+UV-A, by 31% under the full solar spectrum and by 65% with additional UVR. Although growth rates of germlings under UVR were reduced mainly in the first week, the plants did not regain the size of the untreated plants even after 9 weeks. Regardless of the exposure, no defects in morphology or anatomy including the exposed apical meristem were detected, except for a reduction in cell division rates perhaps due to additional cost for photoprotective or repair mechanisms. Depending on the actual position of D. dichotoma plants in the natural habitat, individuals in high positions receive substantial amounts of the more harmful UV-B while those lower down might only receive UV-A during part of the day, thus the effect of UV-B on the growth of D. dichotoma will depend on its position in the field. The effects of tidal variation of the light climate and the implications of our results for the zonation of D. dichotoma are discussed.

  9. Dosimetry for ultraviolet radiation exposure of the eye

    Science.gov (United States)

    Sliney, David H.

    1994-07-01

    The eye is exposed daily to UVR from skylight and ground reflections when outdoors in sunlight. Additional exposure occurs daily from artificial sources such as fluorescent lamps. Some workers, notably welders, are exposed to industrial sources of UVR. The geometry of exposure critically influences the actual UVR dose to the cornea and lens. When exposed to bright light, squinting reduces UVR exposure. the optical properties of the eye and behavioral responses to bright light both contribute to limiting actual UVR exposure. The actual daily dos of UVR is considerably less than what many previous investigators have assumed. The geometrical, as well as temporal and spectral, aspects of ocular dosimetry will be reviewed in order to allow participants a better insight into the practical impact of many laboratory studies of UVR effects upon ocular tissues.

  10. Protection from solar ultraviolet radiation in Hong Kong

    International Nuclear Information System (INIS)

    Increasing skin cancer rates in many countries have been attributed to increasing solar UV radiation due to global depletion of stratospheric ozone. The majority of the existing solar UV radiation monitoring stations are found in high latitude countries nearer to the 2 poles. We are building one such station in Hong Kong at latitude 22.5 degrees N. The station can provide information on solar UV irradiance, exposure limit, irradiance forecast and stratospheric ozone depletion in this region of the world. Protection factors of fabrics and clothing for protecting against solar UV radiation have been determined and analyzed. The spectral transmittances of the fabrics in the wavelength range 250 to 400 nm were measured by means of a solar simulator and a double monochromator spectroradiometer. Effect of washings on the protection factors were simulated and determined. (author)

  11. Physics concepts of solar ultraviolet radiation by distance education

    International Nuclear Information System (INIS)

    A series of activities that are suitable for distance education students to illustrate physics concepts related to solar radiation are described. The students can undertake the activities at any location without having to attend the home institution. Detectors interfaced to computers that make the data available on Web pages are employed. The data are updated every 5 min and can be considered to be in real time. Employing the framework of solar radiation to teach the physics concepts in these activities means that the students can identify how these concepts apply to every day situations

  12. Effects of ultraviolet laser radiation on Venezuelan equine encephalomyelitis virus

    International Nuclear Information System (INIS)

    The effects of usual low-intensity continuous (λ = 254 nm,I = 10 W/m2) UV radiation and high-intensity laser nanosecond (λ = 266 nm, τp = 10 ns, I = 109 W/m2) or picosecond (λ = 266 nm, τp = 23 ps, I = 1012 W/m2) UV radiation on Venezuelan equine encephalomyelitis virus (a member of the Togaviridae family) were compared. The quantum yields of infectivity inactivation, pyrimidine dimer formation and RNA-protein crosslinking were determined. (author)

  13. Prediction of radiation induced liver disease using artificial neural networks

    International Nuclear Information System (INIS)

    The objective of this study was to evaluate the efficiency of predicting radiation induced liver disease (RILD) with an artificial neural network (ANN) model. From August 2000 to November 2004, a total of 93 primary liver carcinoma (PLC) patients with single lesion and associated with hepatic cirrhosis of Child-Pugh grade A, were treated with hypofractionated three-dimensional conformal radiotherapy (3DCRT). Eight out of 93 patients were diagnosed RILD. Ninety-three patients were randomly divided into two subsets (training set and verification set). In model A, the ratio of patient numbers was 1:1 for training and verification set, and in model B, the ratio was 2:1. The areas under receiver-operating characteristic (ROC) curves were 0.8897 and 0.8831 for model A and B, respectively. Sensitivity, specificity, accuracy, positive prediction value (PPV) and negative prediction value (NPV) were 0.875 (7/8), 0.882 (75/85), 0.882 (82/93), 0.412 (7/17) and 0.987 (75/76) for model A, and 0.750 (6/8), 0.800 (68/85), 0.796 (74/93), 0.261 (6/23) and 0.971 (68/70) for model B. ANN was proved high accuracy for prediction of RILD. It could be used together with other models and dosimetric parameters to evaluate hepatic irradiation plans. (author)

  14. EFFECTS OF INCREASED SOLAR ULTRAVIOLET RADIATION ON BIOGEOCHEMICAL CYCLES

    Science.gov (United States)

    Increases in solar UV radiation could affect terrestrial and aquatic biogeochemical cycles thus altering both sources and sinks of greenhouse and chemically important trace gases (e.g., carbon dioxide (CO2), carbon monoxide (CO), carbonyl sulfide (COS)). n terrestrial ecosystems,...

  15. Effects of ultraviolet radiation on the immune system in humans

    International Nuclear Information System (INIS)

    In experimental animals, exposure to UV-B radiation produces selective alterations of immune function which are mainly in the form of suppression of normal immune responses. This immune suppression is important in the development of nonmelanoma skin cancer, may influence the development and course of infectious disease and possibly protects against autoimmune reactions. The evidence that this form of immune suppression occurs in humans is less compelling and very incomplete. The wavelengths of radiation most affected by a depletion of the stratospheric ozone layer are those known to be most immunosuppressive in animals and it is likely that such depletion will increase any suppressive effect of sunlight on immunity in humans. In addition to establishing whether or not UV-B radiation can cause suppression of immune function in humans, studies are required to determine if melanin can provide protection against such suppression, the role of this suppression in the pathogenesis of skin cancer, the development of infectious disease and vaccine effectiveness, and the capacity for humans to develop adaptive, protective mechanisms which may limit damage from continued exposure to UV-B radiation. (author)

  16. A Model for Hourly Solar Radiation Data Generation from Daily Solar Radiation Data Using a Generalized Regression Artificial Neural Network

    OpenAIRE

    Tamer Khatib; Wilfried Elmenreich

    2015-01-01

    This paper presents a model for predicting hourly solar radiation data using daily solar radiation averages. The proposed model is a generalized regression artificial neural network. This model has three inputs, namely, mean daily solar radiation, hour angle, and sunset hour angle. The output layer has one node which is mean hourly solar radiation. The training and development of the proposed model are done using MATLAB and 43800 records of hourly global solar radiation. The results show that...

  17. Assessment of integrated solar ultraviolet radiation by PM-355 detectors

    International Nuclear Information System (INIS)

    The increase in environmental solar UV radiation due to depletion of ozone layer is a recent challenge to human health (skin cancer and eye effects) in countries having clear skies. Therefore, applying integrated, passive and inexpensive techniques to assess solar UV radiation is very much essential. Measurements of environmental solar UV radiation in Dhahran, Saudi Arabia area were carried out for a period of two months in the summer period in 1996 using two techniques in parallel namely: passive nuclear track detectors and active solar UV radiometers. Some of the nuclear track detectors were mounted in different conditions such as: under shadow band, on solar tracking mechanism following the solar rays. Others were mounted on perpendicular, tilted and horizontal surfaces in sunlight. All detectors were attached to a wooden background of the same thickness (0.5 cm) to eliminate interference of the heat effect of various support materials and have uniformity of the support materials. The assessment was carried out for different periods extending from two to nine weeks continuously. The investigated period covered the hottest months in Saudi Arabia (July and August) when the sky was clear of clouds. The results indicate linear correlation between alpha track diameters and the integrated exposure to solar UV as measured by the solar UV radiometer for all nuclear track detector positions and orientations. The highest slope has been observed for the detectors placed on solar tracking mechanism following the solar rays and the lowest from detectors oriented under the shadow band on horizontal position (measuring the diffused UV radiation only). The results show that most of the measured UV radiation (60%) were from the diffused UV radiation. The characteristics of the upper layer of the detectors are changed after chemical etching very quickly, with increase in the exposure time to UV solar radiation at certain orientation. The results encourage the use of nuclear track

  18. Changes in biologically active ultraviolet radiation reaching the Earth's surface.

    Science.gov (United States)

    McKenzie, Richard L; Björn, Lars Olof; Bais, Alkiviadis; Ilyasad, Mohammad

    2003-01-01

    Since publication of the 1998 UNEP Assessment, there has been continued rapid expansion of the literature on UV-B radiation. Many measurements have demonstrated the inverse relationship between column ozone amount and UV radiation, and in a few cases long-term increases due to ozone decreases have been identified. The quantity, quality and availability of ground-based UV measurements relevant to assessing the environmental impacts of ozone changes continue to improve. Recent studies have contributed to delineating regional and temporal differences due to aerosols, clouds, and ozone. Improvements in radiative transfer modelling capability now enable more accurate characterization of clouds, snow-cover, and topographical effects. A standardized scale for reporting UV to the public has gained wide acceptance. There has been increased use of satellite data to estimate geographic variability and trends in UV. Progress has been made in assessing the utility of satellite retrievals of UV radiation by comparison with measurements at the Earth's surface. Global climatologies of UV radiation are now available on the Internet. Anthropogenic aerosols play a more important role in attenuating UV irradiances than has been assumed previously, and this will have implications for the accuracy of UV retrievals from satellite data. Progress has been made inferring historical levels of UV radiation using measurements of ozone (from satellites or from ground-based networks) in conjunction with measurements of total solar radiation obtained from extensive meteorological networks. We cannot yet be sure whether global ozone has reached a minimum. Atmospheric chlorine concentrations are beginning to decrease. However, bromine concentrations are still increasing. While these halogen concentrations remain high, the ozone layer remains vulnerable to further depletion from events such as volcanic eruptions that inject material into the stratosphere. Interactions between global warming and

  19. Tl response of KMgF3: Lu + PTFE at ultraviolet radiation

    International Nuclear Information System (INIS)

    Ionizing radiation has different types of interaction with a crystalline solid. However, only few effects are interesting to optimize some thermoluminescent (Tl) properties of certain Tl materials. This paper presents results obtained by irradiating KMgF3: Lu + Ptfe Tl dosimeters with ultraviolet (UV) radiation previously exposed to gamma radiation. These results showed that those dosimeters not exposed previously to gamma radiation did not presented any Tl signal. Meanwhile, those previously submitted to gamma irradiation showed that their sensitivity was increased as the gamma dose increased. The glow curve of sensitized KMgF3: Lu + Ptfe exposed to UV radiation, presented the dosimetric pea at 212 C. This makes this material to be promissory for measuring UV radiation. (Author)

  20. Ozone depletion - Ultraviolet radiation and phytoplankton biology in Antarctic waters

    Science.gov (United States)

    Smith, R. C.; Prezelin, B. B.; Baker, K. S.; Bidigare, R. R.; Boucher, N. P.; Coley, T.; Karentz, D.; Macintyre, S.; Matlick, H. A.; Menzies, D.

    1992-01-01

    The near-50-percent thinning of the stratospheric ozone layer over the Antarctic, with increased passage of mid-UV radiation to the surface of the Southern Ocean, has prompted concern over possible radiation damage to the near-surface phytoplankton communities that are the bases of Antarctic marine ecosystems. As the ozone layer thinned, a 6-week study of the marginal ice zone of the Bellingshousen Sea in the austral spring of 1990 noted sea-surface and depth-dependent ratios of mid-UV irradiance to total irradiance increased, and mid-UV inhibition of photosynthesis increased. A 6-12 percent reduction in primary production associated with ozone depletion was estimated to have occurred over the course of the present study.

  1. Lethal cellular changes induced by near ultraviolet radiation

    International Nuclear Information System (INIS)

    There is clear evidence that significant quantities of lesions are induced in DNA by near UV radiation and that these lesions, although susceptible to repair, may lead to cell death because of the simultaneous disruption of DNA repair systems by the same wavelengths. No particular DNA lesion can be linked to cell death in wild type strains. However, there are good grounds for speculating that a type of near UV lesion exists which is rapidly 'fixed' as a lethal event in cells as a result of the oxygen-dependent disruption of repair. There is a strong indication that the relative ability of various near UV wavelengths to sensitize cells to heat, chemicals or other radiations is directly related to their efficiency in disrupting DNA repair systems in general. (author)

  2. Influence of extremely low energy radiation on artificial tissue: Effects on image quality and superficial dose

    OpenAIRE

    Al-Akhras, M.-Ali H.; Aljarrah, K.; A Al-omari; H M Al-Khateeb; Albiss, B. A.; Azez, K.; Makhadmeh, G.

    2008-01-01

    The design and slicing technique of artificial soft tissue are presented. Artificial soft tissue has optical penetration properties similar to biological tissues. The soft tissues are made of agar dissolved in water as a transparent tissue (control) incorporated with scatter materials such as polystyrene microspheres and absorbers such as artificial dairy substitute, coffee mate (Carnation Co.). The radiation's interaction with 20 and 40 keV X-ray, and visible light (400–800 nm) with differen...

  3. Effects of increased solar ultraviolet radiation on biogeochemical cycles

    International Nuclear Information System (INIS)

    Increases in solar UV radiation could affect terrestrial and aquatic biogeochemical cycles thus altering both sources and sinks of greenhouse and chemically important trace gases (e.g., carbon dioxide (CO2), carbon monoxide (CO), carbonyl sulfide (COS). In terrestrial ecosystems, increased UV-B could modify both the production and decomposition of plant matter with concomitant changes in the uptake and release of atmospherically important trace gases. Decomposition processes can be accelerated when UV-B photodegrades surface litter, or retarded when the dominant effect involves changes in the chemical composition of living tissues that reduce the biodegradability of buried litter. These changes in decomposition can affect microbial production of CO2 and other trace gases and also may affect the availability of nutrients essential for plant growth. Primary production can be reduced by enhanced UV-B, but the effect is variable between species and even cultivars of some crops. Likewise, the effects of enhanced UV-B on photoproduction of CO from plant matter is species-dependent and occurs more efficiently from dead than from living matter. Aquatic ecosystems studies in several different locations have shown that reductions in current levels of solar UV-B result in enhanced primary production, and Antarctic experiments under the ozone hole demonstrated that primary production is inhibited by enhanced UV-B. In addition to its effects on primary production, solar UV radiation can reduce bacterioplankton growth in the upper ocean with potentially important effects on marine biogeochemical cycles. Decomposition processes can be retarded when bacterial activity is suppressed by enhanced UV-B radiation or stimulated when solar UV radiation photodegrades aquatic dissolved organic matter. Photodegradation of DOM results in loss of UV absorption and formation of dissolved inorganic carbon, CO, and organic substrates that are readily mineralized or taken up by aquatic

  4. Short communication: Artificial ultraviolet B light exposure increases vitamin D levels in cow plasma and milk

    DEFF Research Database (Denmark)

    Jakobsen, Jette; Jensen, Søren Krogh; Hymøller, Lone;

    2015-01-01

    group with simulated exposure to 2 h of summer sun daily continued to be monitored for 73 d. We found a significant increase in 25-hydroxyvitamin D-3 (25OHD(3)) levels in plasma as well as vitamin D-3 and 25OHD(3) levels in milk after daily exposure for 24 d in all treatment groups. Extending daily...... exposure to artificial UVB light to 73 d did not lead to an increase of vitamin D-3 or 25OHD(3) level in the milk. In conclusion, the change in production facilities for dairy cows providing cows with no access to pasture and sunlight causes a decrease of vitamin D levels in dairy products. This decrease...

  5. Collagen structural hierarchy and susceptibility to degradation by ultraviolet radiation

    International Nuclear Information System (INIS)

    Collagen type I is the most abundant extracellular matrix protein in the human body, providing the basis for tissue structure and directing cellular functions. Collagen has complex structural hierarchy, organized at different length scales, including the characteristic triple helical feature. In the present study, the relationship between collagen structure (native vs. denatured) and sensitivity to UV radiation was assessed, with a focus on changes in primary structure, changes in conformation, microstructure and material properties. A brief review of free radical reactions involved in collagen degradation is also provided as a mechanistic basis for the changes observed in the study. Structural and functional changes in the collagens were related to the initial conformation (native vs. denatured) and the energy of irradiation. These changes were tracked using SDS-PAGE to assess molecular weight, Fourier transform infrared (FTIR) spectroscopy to study changes in the secondary structure, and atomic force microscopy (AFM) to characterize changes in mechanical properties. The results correlate differences in sensitivity to irradiation with initial collagen structural state: collagen in native conformation vs. heat-treated (denatured) collagen. Changes in collagen were found at all levels of the hierarchical structural organization. In general, the native collagen triple helix is most sensitive to UV-254 nm radiation. The triple helix delays single chain degradation. The loss of the triple helix in collagen is accompanied by hydrogen abstraction through free radical mechanisms. The results received suggest that the effects of electromagnetic radiation on biologically relevant extracellular matrices (collagen in the present study) are important to assess in the context of the state of collagen structure. The results have implications in tissue remodeling, wound repair and disease progression

  6. Inactivation of certain insect pathogens by ultraviolet radiation

    International Nuclear Information System (INIS)

    The UV-sensitivity of two baculoviruses (granulosis virus, nuclear polyhedrosis virus) and two entomopathogenic microorganisms (Bacillus thuringiensis, Beauveria bassiana) was determined by radiation tests. In the far UV (254 nm) the stability, measured at an inactivation rate of 99%, was in declining order: nuclear polyhedra >= conidia of B. bassiana > granula > spores of B. thuringiensis >= vegetative cells of B. thuringiensis. In the near UV (285-380 nm) the following order could be found: conidia of B. bassiana >= nuclear polyhedra > spores of B. thuringiensis >= granula > vegetative cells of B. thuringiensis. Far UV had a much higher germicidal effect for all pathogens tested than near UV. (orig.)

  7. Effects of ultraviolet and electron radiations on graphite-reinforced polysulfone and epoxy resins

    International Nuclear Information System (INIS)

    Degradation mechanisms have been investigated for graphite/polysulfone and graphite/epoxy laminates exposed to ultraviolet and high-energy electron radiations in vacuum up to 960 equivalent sun hours and 109 rads, respectively. Based on GC and combined GC/MS analysis of volatile by-products evolved during irradiation, several free radical mechanisms of composite degradation have been identified. All the composite materials evaluated have shown high electron radiation stability and relatively low ultraviolet stability as indicated by low G values and high quantum yields for gas formation. Mechanical property measurements of irradiated samples did not reveal significant changes, with the possible exception of UV exposed polysulfone laminates. Hydrogen and methane have been identified as the main byproducts of irradiation, along with unexpectedly high levels of CO and CO2. Initial G values for methane relative to hydrogen formation are higher in the presence of isopropylidene linkages, which occur in bisphenol-A resins

  8. Ultraviolet radiation monitoring in makkah city, Saudi Arabia, using thermoluminescence material CaF2:Tm

    International Nuclear Information System (INIS)

    The aim of the present study is to explore the possibility of using Ca F2:Tm thermoluminescence material for measuring and monitoring of solar UV R in Makkah City, Saudi Arabia. Several laboratory experiments, prior to the field measurements, were performed included study of the effects of ultraviolet wavelengths on the response of the phosphor, study of the effect of increasing ultraviolet radiation dose on the intensity of thermoluminescence and study the effect of time factor on the thermoluminescence fading of Ca F2:Tm. The phosphor was then exposed directly for one hour to sunlight radiation on a daily basis for 90 days in an open field inside Umm Al-Qura university campus. The field measurements were performed during the months of June, July and August 2003 at 1:00 p.m. The laboratory and field results of this study showed that Ca F2:Tm can be used as a suitable dosimeter for solar UV R

  9. Ultrastructural effects of ultraviolet C radiation on the stratum basale of mole rats epidermis

    Directory of Open Access Journals (Sweden)

    Mustafa Yel

    2014-10-01

    Full Text Available The ultrastructure of the epidermis of mole rats (Spalax leucodon was studied after irradiation with ultraviolet (UV light (λmax = 254 nm; 0.00147 J cm−2 s−1; for periods of 52, 112 and 168 h by using transmission electron microscope (TEM. After irradiation, Vacuolation in cytoplasm and mitochondria, and wrinkled nucleus were found in the stratum basal cells. Also, pathological aggregations of tonofilaments are formed in the desmosomes in these cells. These findings clearly demonstrated the harmful effects of ultraviolet C radiation on the stratum basale. The degree of pathological changes occurred depending on exposure time and radiation dosage applied.

  10. Optical effects of exposing intact human lenses to ultraviolet radiation and visible light

    DEFF Research Database (Denmark)

    Kessel, Line; Eskildsen, Lars; Lundeman, Jesper Holm;

    2011-01-01

    region of incoming visible light. The aim of the present study was to examine the optical effects on human lenses of short wavelength visible light and ultraviolet radiation. METHODS: Naturally aged human donor lenses were irradiated with UVA (355 nm), violet (400 and 405 nm) and green (532 nm) lasers......BACKGROUND: The human lens is continuously exposed to high levels of light. Ultraviolet radiation is believed to play a causative role in the development of cataract. In vivo, however, the lens is mainly exposed to visible light and the ageing lens absorbs a great part of the short wavelength....... The effect of irradiation was evaluated qualitatively by photography and quantitatively by measuring the direct transmission before and after irradiation. Furthermore, the effect of pulsed and continuous laser systems was compared as was the effect of short, intermediate and prolonged exposures...

  11. Optical effects of exposing intact human lenses to ultraviolet radiation and visible light

    DEFF Research Database (Denmark)

    Kessel, Line; Eskildsen, Lars Baunsgaard; Lundeman, Jesper Holm;

    2011-01-01

    wavelength region of incoming visible light. The aim of the present study was to examine the optical effects on human lenses of short wavelength visible light and ultraviolet radiation. METHODS: Naturally aged human donor lenses were irradiated with UVA (355 nm), violet (400 and 405 nm) and green (532 nm......ABSTRACT: BACKGROUND: The human lens is continuously exposed to high levels of light. Ultraviolet radiation is believed to play a causative role in the development of cataract. In vivo, however, the lens is mainly exposed to visible light and the ageing lens absorbs a great part of the short......) lasers. The effect of irradiation was evaluated qualitatively by photography and quantitatively by measuring the direct transmission before and after irradiation. Furthermore, the effect of pulsed and continuous laser systems was compared as was the effect of short, intermediate and prolonged exposures...

  12. Comparing vacuum and extreme ultraviolet radiation for postionization of laser desorbed neutrals from bacterial biofilms and organic fullerenes

    International Nuclear Information System (INIS)

    Vacuum and extreme ultraviolet radiation from 8 to 24 eV generated at a synchrotron was used to postionize laser desorbed neutrals of antibiotic-treated biofilms and a modified fullerene using laser desorption postionization mass spectrometry (LDPI-MS). Results show detection of the parent ion, various fragments, and extracellular material from biofilms using LDPI-MS with both vacuum and extreme ultraviolet photons. Parent ions were observed for both cases, but extreme ultraviolet photons (16-24 eV) induced more fragmentation than vacuum ultraviolet (8-14 eV) photons.

  13. Reduction of arsenite-enhanced ultraviolet radiation-induced DNA damage by supplemental zinc

    OpenAIRE

    Cooper, Karen L.; King, Brenee S.; Sandoval, Monica M.; Liu, Ke Jian; Hudson, Laurie G.

    2013-01-01

    Arsenic is a recognized human carcinogen and there is evidence that arsenic augments the carcinogenicity of DNA damaging agents such as ultraviolet radiation (UVR) thereby acting as a co-carcinogen. Inhibition of DNA repair is one proposed mechanism to account for the co-carcinogenic actions of arsenic. We and others find that arsenite interferes with the function of certain zinc finger DNA repair proteins. Furthermore, we reported that zinc reverses the effects of arsenite in cultured cells ...

  14. Indirect evidence that ultraviolet-B radiation mitigates multiple sclerosis in the United States.

    Science.gov (United States)

    Davis, George E; Lowell, Walter E

    2015-10-01

    This article describes on the relationship of the relative prevalence of persons dying with multiple sclerosis with the latitude of the population centroid of those affected in each of the United States. Regression to zero prevalence occurs at the Tropic of Cancer, the latitude where the Sun is at zenith on the summer solstice and where ultraviolet radiation (UVR) is least attenuated. This observation supports UVR as a mitigating force in multiple sclerosis. PMID:26163947

  15. Correcting spaceborne reflectivity measurements for application in solar ultraviolet radiation levels calculations at ground level

    OpenAIRE

    P. N. den Outer; Dijk, A. van; Slaper, H.; A. V. Lindfors; Backer, H; A. F. Bais; Feister, U.; Koskela, T.; Josefsson, W.

    2012-01-01

    The Lambertian Equivalent Reflection (LER) produced by satellite-carried instruments is used to determine cloud effects on ground level UltraViolet (UV) radiation. The focus is on data use from consecutive operating instruments: the Total Ozone Mapping Spectrometers (TOMS) flown on Nimbus 7 from 1979 to 1992, TOMS on Earth Probe from 1996 to 2005, and the Ozone Monitoring Instrument (OMI) flown on Aura since 2004. The LER data produced by TOMS on Earth Probe is only included until 2002. ...

  16. Generation of Coherent Extreme-Ultraviolet Radiation Carrying Orbital Angular Momentum

    OpenAIRE

    Ribič, Primož Rebernik; Gauthier, David; De Ninno, Giovanni

    2013-01-01

    We propose an effective scheme for the generation of intense coherent extreme ultraviolet light beams carrying orbital angular momentum (OAM). The light is produced by a high-gain harmonic-generation free-electron laser (FEL), seeded using a laser pulse with a transverse staircase-like phase pattern. During amplification, diffraction and mode selection drive the radiation profile towards a dominant OAM mode at saturation. With a seed laser at 260 nm, gigawatt power levels are obtained at wave...

  17. Green algae in alpine biological soil crust communities: acclimation strategies against ultraviolet radiation and dehydration

    OpenAIRE

    Karsten, Ulf; Holzinger, Andreas

    2014-01-01

    Green algae are major components of biological soil crusts in alpine habitats. Together with cyanobacteria, fungi and lichens, green algae form a pioneer community important for the organisms that will succeed them. In their high altitudinal habitat these algae are exposed to harsh and strongly fluctuating environmental conditions, mainly intense irradiation, including ultraviolet radiation, and lack of water leading to desiccation. Therefore, green algae surviving in these environments must ...

  18. Monitoring of the atmospheric ozone layer and natural ultraviolet radiation: Annual report 2011

    Energy Technology Data Exchange (ETDEWEB)

    Svendby, T.M.; Myhre, C.L.; Stebel, K.; Edvardsen, K; Orsolini, Y.; Dahlback, A.

    2012-07-01

    This is an annual report describing the activities and main results of the monitoring programme: Monitoring of the atmospheric ozone layer and natural ultraviolet radiation for 2011. 2011 was a year with generally low ozone values above Norway. A clear decrease in the ozone layer above Norway during the period 1979-1997 stopped after 1998 and the ozone layer above Norway seems now to have stabilized.(Author)

  19. Scientific Assessment of Ozone Depletion: 2010, Chapter 2 - Stratospheric Ozone and Surface Ultraviolet Radiation

    OpenAIRE

    Douglass, A.; Fioletov, V.; Godin-Beekmann, Sophie; Müller, R; Stolarski, R. S.; Webb, A; Arola, A.; Burkholder, J. B.; Burrows, J. P.; Chipperfield, M. P.; Cordero, R.; David, C.; Den Outer, P. N.; S. B. Diaz; Flynn, L. E.

    2011-01-01

    As a result of the Montreal Protocol, ozone is expected to recover from the effect of ozone-depleting substances (ODSs) as their abundances decline in the coming decades. The 2006 Assessment showed that globally averaged column ozone ceased to decline around 1996, meeting the criterion for the first stage of recovery. Ozone is expected to increase as a result of continued decrease in ODSs (second stage of recovery). This chapter discusses recent observations of ozone and ultraviolet radiation...

  20. In Vivo NMR Metabolic Profiling of Fabrea salina Reveals Sequential Defense Mechanisms against Ultraviolet Radiation

    OpenAIRE

    Marangoni, Roberto; Paris, Debora; Melck, Dominique; Fulgentini, Lorenzo; Colombetti, Giuliano; Motta, Andrea

    2011-01-01

    Fabrea salina is a hypersaline ciliate that is known to be among the strongest ultraviolet (UV)-resistant microorganisms; however, the molecular mechanisms of this resistance are almost unknown. By means of in vivo NMR spectroscopy, we determined the metabolic profile of living F. salina cells exposed to visible light and to polychromatic UV-B + UV-A + Vis radiation for several different exposure times. We used unsupervised pattern-recognition analysis to compare these profiles and discovered...

  1. Melanocortin 1 receptor genotype: an important determinant of the damage response of melanocytes to ultraviolet radiation

    OpenAIRE

    Kadekaro, Ana Luisa; Leachman, Sancy; Kavanagh, Renny J.; Swope, Viki; Cassidy, Pamela; Supp, Dorothy; Sartor, Maureen; Schwemberger, Sandy; Babcock, George; Wakamatsu, Kazumasa; Ito, Shosuke; Koshoffer, Amy; Boissy, Raymond E.; Manga, Prashiela; Sturm, Richard A.

    2010-01-01

    The melanocortin 1 receptor gene is a main determinant of human pigmentation, and a melanoma susceptibility gene, because its variants that are strongly associated with red hair color increase melanoma risk. To test experimentally the association between melanocortin 1 receptor genotype and melanoma susceptibility, we compared the responses of primary human melanocyte cultures naturally expressing different melanocortin 1 receptor variants to α-melanocortin and ultraviolet radiation. We found...

  2. Solar ultraviolet radiation: properties, characteristics and amounts observed in Brazil and South America*

    OpenAIRE

    Corrêa, Marcelo de Paula

    2015-01-01

    The beneficial and harmful effects of human exposure to solar ultraviolet radiation (UV-R) are topics that arouse great interest not only among physicians and scientists, but also the general public and the media. Currently, discussions on vitamin D synthesis (beneficial effect) are confronted with the high and growing number of new cases of non-melanoma skin cancer and other diseases of the skin and eyes (harmful effect) diagnosed each year in Brazil. However, the lack of scientific knowledg...

  3. Bow-tie nano-antenna assisted generation of extreme ultraviolet radiation

    OpenAIRE

    Pfullmann, N.; Waltermann, C.; Noack, M.; Rausch, S.; Nagy, T.; Reinhardt, C.; Kovacev, M.; Knittel, V.; Bratschitsch, R.; Akemeier, D.; Huetten, A.; Leitenstorfer, A.; Morgner, Uwe

    2013-01-01

    We report on the generation of extreme ultraviolet radiation utilizing the plasmonic field enhancement in arrays of bow-tie gold optical antennae. Furthermore, their suitability to support high-order harmonic generation is examined by means of finite-difference time-domain calculations and experiments. Particular emphasis is paid to the thermal properties, which become significant at the employed peak intensities. A damage threshold depending on the antenna length is predict...

  4. Green tea catechins and their metabolites in human skin before and after exposure to ultraviolet radiation

    OpenAIRE

    Clarke KA, Dew TP, Watson RE, Farrar MD, Osman JE, Nicolaou A, Rhodes LE, Williamson G

    2016-01-01

    Dietary flavonoids may protect against sunburn inflammation in skin. Preliminary reports using less complete analysis suggest that certain catechins and their metabolites are found in skin biopsies and blister fluid after consumption of green tea; however, it is not known if they are affected by solar-simulated ultraviolet radiation (UVR) or whether conjugated forms, with consequently altered bioactivity, are present. The present study tested the hypothesis that UVR affects the catechin level...

  5. Reducing ultraviolet radiation exposure among outdoor workers: State of the evidence and recommendations

    OpenAIRE

    Buller David B; Saraiya Mona; Glanz Karen

    2007-01-01

    Abstract Objective Outdoor workers have high levels of exposure to ultraviolet radiation and the associated increased risk of skin cancer. This paper describes a review of: 1) descriptive data about outdoor workers' sun exposure and protection and related knowledge, attitudes, and policies and 2) evidence about the effectiveness of skin cancer prevention interventions in outdoor workplaces. Data sources Systematic evidence-based review. Data synthesis We found variable preventive practices, w...

  6. TOMS as a monitor of the ultraviolet radiation environment: Applications to photobiology

    Science.gov (United States)

    Frederick, John E.

    1987-01-01

    The flux of biologically relevant ultraviolet radiation that reaches the surface of the Earth varies with the ozone amount, surface reflectivity, and cloudcover. The Total Ozone Mapping Spectrometer (TOMS) provides information relevant to all three items. A recent application of satellite-based ozone measurements has been to develop climatologies of the biologically significant UV-B radiation reaching the Earth's surface. A growing body of research suggests that UV-B radiation tends to suppress the immune system of laboratory mice. At tropical latitudes, it is likely that parasitical diseases develop most readily in people who have experienced immune system suppression from UV-B exposure. The computed distribution of surface radiation combined with information on disease incidence may clarify the role of UV-B as a suppressor of the human immune system. TOMS used in conjunction with radiative transfer calculations can provide information of relevance in photobiology.

  7. The effect of ultraviolet radiation on the delayed type hypersensitivity using allogeneic epidermal cell antigens

    International Nuclear Information System (INIS)

    Low dose of ultraviolet B (UVB) radiation have been shown to impair the ability of epidermal cells (EC). We studied the effect of the UVB radiation on the delayed type hypersensitivity (DTH) induced by allogeneic EC. The DTH response was assayed by their footpad swelling. When EC were exposed to UVB radiation (660 J/m2), their ability to lead to TDTH activation was markedly inhibited in any combination of recipient mice and EC. The effect of UVB radiation on EC was observed before immunization and challenge. UVB treated EC did not induce suppressor T cells(Ts) in mice, which Ts might be induced by intravenous injection of EC. These results indicate that UVB radiation abrogates antigenicity of EC. (author)

  8. Local defects of erythrocytes membranes nanostructure under the action of ultraviolet radiation on blood

    International Nuclear Information System (INIS)

    The aim is to study the local topological defects of erythrocytes membranes resulting from the action of ultraviolet (UV) radiation on the blood, in vitro. Biological effects of the erythrocytes after exposure to UV radiation with a wavelength λ = 254 nm are much similar to the effects when exposed to γ radiation. It is shown that the oxidative processes that occur in the suspension under the action of UV radiation resulted in disruption of the membranes of erythrocytes nanostructure. In the experiments there were observed typical topological defects of membranes nanostructure. Parameters of defects differ from the characteristics of the control cell membrane nanostructure without irradiation. The characteristic dimensions of topological defects are commensurate with the size of spectrin matrix. As a result of exposure to UV radiation polymorphism of erythrocytes was observed

  9. The underprotective features of the sediment quality criterion for fluoranthene in the presence of ultraviolet radiation

    International Nuclear Information System (INIS)

    The goal of this study was to evaluate the fluoranthene sediment quality criterion (SQC) for the protection of benthic organisms in the presence of ultraviolet (UV) radiation. The authors exposed the benthic amphipod Hyalella azteca to clean and fluoranthene-spiked sediments at the SQC concentration (620 microg/goc) in the presence or absence of UV radiation. When UV radiation was used the test-organisms showed signs of stress (slow response to physical disturbance) after 48 hrs. When comparing the data of adults vs. juveniles, the authors found that the adults were more sensitive. After 5 days of exposure 90% of the adults were dead vs. 62% of the juveniles. This could have been the result of greater exposure to UV radiation caused by a larger body surface area on the adults. Studies of the combined effects of fluoranthene contaminated sediments and UV radiation using benthic organisms indicate that the current fluoranthene SOC requires further examination

  10. Ultraviolet radiation-mediated damage to cellular DNA

    Energy Technology Data Exchange (ETDEWEB)

    Cadet, Jean [Laboratoire Lesions des Acides Nucleiques, Service de Chimie Inorganique et Biologique, CEA/DSM/Departement de Recherche Fondamentale sur la Matiere Condensee, CEA-Grenoble, 17, Av. des Martyrs, Grenoble Cedex 9 F-38054 (France)]. E-mail: jcadet@cea.fr; Sage, Evelyne [Institut Curie, CNRS/IC UMR 2027, Centre Universitaire, Orsay (France); Douki, Thierry [Laboratoire Lesions des Acides Nucleiques, Service de Chimie Inorganique et Biologique, CEA/DSM/Departement de Recherche Fondamentale sur la Matiere Condensee, CEA-Grenoble, 17, Av. des Martyrs, Grenoble Cedex 9 F-38054 (France)

    2005-04-01

    Emphasis is placed in this review article on recent aspects of the photochemistry of cellular DNA in which both the UVB and UVA components of solar radiation are implicated individually or synergistically. Interestingly, further mechanistic insights into the UV-induced formation of DNA photoproducts were gained from the application of new accurate and sensitive chromatographic and enzymic assays aimed at measuring base damage. Thus, each of the twelve possible dimeric photoproducts that are produced at the four main bipyrimidine sites can now be singled out as dinucleoside monophosphates that are enzymatically released from UV-irradiated DNA. This was achieved using a recently developed high-performance liquid chromatography-tandem mass spectrometry assay (HPLC-MS/MS) assay after DNA extraction and appropriate enzymic digestion. Interestingly, a similar photoproduct distribution pattern is observed in both isolated and cellular DNA upon exposure to low doses of either UVC or UVB radiation. This applies more specifically to the DNA of rodent and human cells, the cis-syn cyclobutadithymine being predominant over the two other main photolesions, namely thymine-cytosine pyrimidine (6-4) pyrimidone adduct and the related cyclobutyl dimer. UVA-irradiation was found to generate cyclobutane dimers at TT and to a lower extent at TC sites as a likely result of energy transfer mechanism involving still unknown photoexcited chromophore(s). Oxidative damage to DNA is also induced although less efficiently by UVA-mediated photosensitization processes that mostly involved {sup 1}O{sub 2} together with a smaller contribution of hydroxyl radical-mediated reactions through initially generated superoxide radicals.

  11. A study of ultraviolet solar radiation at Cairo urban area, Egypt

    Energy Technology Data Exchange (ETDEWEB)

    Robaa, S.M. [Cairo Univ., Giza (Egypt). Dept. of Astronomy and Meterology

    2004-07-01

    The monthly mean values of global, G, and ultraviolet, UV, solar radiation incident on a horizontal surface at Cairo urban area during the two different periods (1969-1973) and (1993-1997) are presented, analyzed and compared. The effect of urbanization processes on the solar radiation components is investigated and discussed. It was found that the total radiation of the two components, G and UV received at the urban area of Cairo during the period (1969-1973) highly exceeds the radiation received during the period (1993-1997) for all months of the year. The mean relative reduction of G and UV reached 17.4% and 27.4% respectively. A significant correlation between G and UV radiation has been established and the recommended correlation equation has been stated to estimate the values of UV radiation that are difficult to measure at any site in the zone of Lower Egypt. Also, a comparative study of the two radiation components, G and UV, at urban (Cairo) and rural (Bahtim) areas during the period (1993-1997) revealed that the urban area always has values of G and UV radiation distinctly lower than that found in rural area for all months of the year. Urban-rural mean reduction of G and UV reached 7.0% and 17.9% respectively. The ratio of the ultraviolet to global radiation (UV/G) are calculated and compared with other sites in the Arabian Peninsula. The effect of atmospheric dust on the measured solar radiation components is also investigated and discussed. (author)

  12. Preparation of SiO2 films in heterogeneous dissociation of tetraethoxysilane in ultraviolet radiation

    International Nuclear Information System (INIS)

    Intensive research has been carried out in recent years into nonthermal activation of the processes of surface treatment of semiconductor materials with the formation of film structures. In addition to laser radiation whose physics of interaction with the solid has been studied most extensively, these investigations have been carried out using other physical methods of activation - electric field, and ultraviolet radiation, which have been studied less extensively. All of these methods are characterised by the localisation of the energy effect in sub-surface the regions of the solid and, consequently, by the absence of secondary processes of migration and degradation in its volume. This is a considerable advantage of the processes in this direction in comparison with conventional processes, with their total thermal effect of the entire crystal. One of these processes is the production of thin films of silica on neutral and active substrates by gas-phase deposition from a mixture of tetraetoxysilane (TEOS) on the surface of a silicon substrate during the process of formation of silica film under the effect of ultraviolet radiation. The theoretical basis of the evaluation was a presented by the following considerations. The energy effect of ultraviolet radiation on the TEOS molecule takes place twice: directly in the gas phase as a result of absorption of the radiation energy by the molecules (and their excitation) and later: the surface of silicon as a result of the absorption of radiation energy by surface active centres and the transfer of the adsorbed excitation energy to the molecules adsorbed on them. Since the mean activation energy of dissociation of the TEOS molecule in the non-excited state is quite high (∼ 3500 kJ/mole), we did not consider the low-probability breakdown of the molecules in the gas phase and consider dissociation only with the surface of the substrate taking part in it

  13. Biologically relevant physical measurements in the ice-free valleys of southern Victoria Land: soil temperature profiles and ultraviolet radiation

    Science.gov (United States)

    Nienow, J. A.; Meyer, M. A.; Friedmann, E. I. (Principal Investigator)

    1986-01-01

    As part of the ongoing comprehensive study of the cryptoendolithic microbial community in the ice-free valleys of southern Victoria Land, thermal properties of the soil and the ultraviolet radiation regime were measured. Although soil temperature profiles have been measured in the ice-free valleys (e.g., Cameron et al. 1970; Cameron 1972), these are the first such data from higher elevations. This is apparently the first time the ultraviolet radiation regime has been measured in the Antarctic.

  14. Icecolors '93: Epilithic productivity by microalgae exhibits a potentially high sensitivity to natural levels of ultraviolet-B radiation

    International Nuclear Information System (INIS)

    Increased ultraviolet-B [UV-B, 280-320 nanometers (nm)] radiation associated with the depletion of stratospheric ozone (O3) over Antarctica during the austral spring has a negative impact on phytoplankton and sea-ice algae productivity. The Icecolors 1993 expedition documented the potential impact of ultraviolet radiation (UVR) on littoral microalgae (lithophytes), which are almost always highly exposed to deleterious light effects. 7 refs., 2 figs., 1 tab

  15. Flavonoids can protect maize DNA from the induction of ultraviolet radiation damage

    International Nuclear Information System (INIS)

    Diverse flavonoid compounds are widely distributed in angiosperm families. Flavonoids absorb radiation in the ultraviolet (UV) region of the spectrum, and it has been proposed that these compounds function as UV filters. We demonstrate that the DNA in Zea mays plants that contain flavonoids (primarily anthocyanins) is protected from the induction of damage caused by UV radiation relative to the DNA in plants that are genetically deficient in these compounds. DNA damage was measured with a sensitive and simple assay using individual monoclonal antibodies, one specific for cyclobutane pyrimidine dimer damage and the other specific for pyrimidine(6,4)pyrimidone damage. (author)

  16. Effect of Lanthanum on Plants under Supplementary Ultraviolet-B Radiation: Effect of Lanthanum on Flavonoid Contents in Soybean Seedlings Exposed to Supplementary Ultraviolet-B Radiation

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The effect of La on flavonoids, chlorophyll contents, and phenylalanine ammonia-lyase (PAL) activity in soybean seedlings under supplementary ultraviolet-B radiation (UV-B, 280 ~ 320 nm) was studied. The results show that PAL activity, contents of flavonoids and chlorophyll in the plants pretreated with La (20 mg· L-1) are higher than those in CK. UV-B radiation could result in an increase in flavonoid content and PAL activity, associated with a decrease in chlorophyll content. However, the increase in the range of PAL activity and flavonoid content in UV-B treatment are lesser than those in the La treatment. The changes of flavonoid contents and PAL activity in La + UV-B treatment are similar to those in UV-B treatment, and the increase in their range is higher than those in UV-B treatment. This shows that La can enhance the resistance of soybean seedling to UV-B radiation and alleviate the damage of UV-B radiation by increasing flavonoid content, chlorophyll content, and PAL activity.

  17. Ultraviolet radiation and bio-optics in Crater Lake, Oregon

    Science.gov (United States)

    Hargreaves, B.R.; Girdner, S.F.; Buktenica, M.W.; Collier, R.W.; Urbach, E.; Larson, G.L.

    2007-01-01

    Crater Lake, Oregon, is a mid-latitude caldera lake famous for its depth (594 m) and blue color. Recent underwater spectral measurements of solar radiation (300-800 nm) support earlier observations of unusual transparency and extend these to UV-B wavelengths. New data suggest that penetration of solar UVR into Crater Lake has a significant ecological impact. Evidence includes a correlation between water column chlorophyll-a and stratospheric ozone since 1984, the scarcity of organisms in the upper water column, and apparent UV screening pigments in phytoplankton that vary with depth. The lowest UV-B diffuse attenuation coefficients (K d,320) were similar to those reported for the clearest natural waters elsewhere, and were lower than estimates for pure water published in 1981. Optical proxies for UVR attenuation were correlated with chlorophyll-a concentration (0-30 m) during typical dry summer months from 1984 to 2002. Using all proxies and measurements of UV transparency, decadal and longer cycles were apparent but no long-term trend since the first optical measurement in 1896. ?? 2007 Springer Science+Business Media B.V.

  18. Ultraviolet solar radiation in the high latitudes of South America

    Energy Technology Data Exchange (ETDEWEB)

    Frederick, J.E.; Esposito, W. [Chicago Univ., IL (United States). Dept. of Geophysical Sciences; Diaz, S.B.; Smolskaia, I. [Centro Austral de Investigaciones Cientificas, Ushuaia, Tierra del Fuego (Argentina); Lucas, T.; Booth, C.R. [Biospherical Instruments Inc., San Diego, CA (United States)

    1994-10-01

    Measurements of the UV solar irradiance are available from Ushuaia, Tierra del Fuego during the spring and summer seasons of 4 consecutive years beginning in 1989. In addition, column zone amounts derived from satellite-based measurements exist for this location over the entire period from 1980 through 1991. Monthly mean column ozone over Ushuaia shows a general decline over the observing period, and a large day-to-day variability exists within a given month. Ozone amounts for the years 1980 through 1986 combined with a model of radiative transfer provide a climatological baseline against which to interpret the more recent ground-based irradiance data. We focus on monthly mean noontime irradiances integrated over 5nm wide spectral bands near 305 nm and 340 nm respectively. Measurements in the 340 nm band show that cloudiness has a large influence on both the absolute monthly mean irradiances and their interannual variability. For example, during December the 340 nm band irradiance varied from approximately 50% of the clear-sky value in 1992 to 65% in 1991. When the influence of cloudiness is removed, most of the months show irradiances in the 305 nm band that are larger than predicted from the climatological ozone amounts. The largest percentage enhancement occurred in October 1991 when the irradiance exceeded the baseline by 56%. The largest absolute irradiances occur in December, where the measurements range from 5.8% below the baseline in 1991 to 31% above in 1990. (author).

  19. Ultraviolet solar radiation in the high latitudes of South America

    International Nuclear Information System (INIS)

    Measurements of the UV solar irradiance are available from Ushuaia, Tierra del Fuego during the spring and summer seasons of 4 consecutive years beginning in 1989. In addition, column zone amounts derived from satellite-based measurements exist for this location over the entire period from 1980 through 1991. Monthly mean column ozone over Ushuaia shows a general decline over the observing period, and a large day-to-day variability exists within a given month. Ozone amounts for the years 1980 through 1986 combined with a model of radiative transfer provide a climatological baseline against which to interpret the more recent ground-based irradiance data. We focus on monthly mean noontime irradiances integrated over 5nm wide spectral bands near 305 nm and 340 nm respectively. Measurements in the 340 nm band show that cloudiness has a large influence on both the absolute monthly mean irradiances and their interannual variability. For example, during December the 340 nm band irradiance varied from approximately 50% of the clear-sky value in 1992 to 65% in 1991. When the influence of cloudiness is removed, most of the months show irradiances in the 305 nm band that are larger than predicted from the climatological ozone amounts. The largest percentage enhancement occurred in October 1991 when the irradiance exceeded the baseline by 56%. The largest absolute irradiances occur in December, where the measurements range from 5.8% below the baseline in 1991 to 31% above in 1990. (author)

  20. Repair of DNA damage induced by ultraviolet radiation

    International Nuclear Information System (INIS)

    Studies documenting the depletion of the ozone layer and the resulting increases in UV-B radiation (280-320 nm) at the Earth's surface have served to focus attention on the biological effects of UV light. One obvious target for UVB- induced damage is DNA. Although a11 biological tissues are rich in UV-absorbing agents (largely nucleic acids and proteins) and plants produce additional UV-absorbing pigments, no DNA in superficial tissue can completely avoid UV exposure. Plants, like a11 living organisms, must have some capacity for the repair of UV-induced DNA damage. Because plants are unique in the obligatory nature of their exposure to UV, it is also conceivable that they may have evolved particularly efficient mechanisms for the elimination of UV-induced DNA damage. This review will summarize what we know about DNA repair mechanisms in higher plants. Readers interested in broader aspects of UV-induced damage and UV filters are directed to recent reviews (Middleton and Teramura, 1994; Strid et al., 1994; Fiscus and Booker, 1995). Our knowledge of DNA repair mechanisms in plants lags far behind our understanding of these pathways in animals, and a significant number of questions concerning the basic phenomenology of DNA repair in plants remain to be addressed

  1. Synchrotron radiation: a new tool for biophysical spectroscopy in the visible and ultraviolet

    Energy Technology Data Exchange (ETDEWEB)

    Sutherland, J C

    1978-01-01

    Spectroscopy in the ultraviolet, visible and near infrared regions of the electromagnetic spectrum is extremely important in the study of biological materials. These lectures consider the applications of synchrotron radiation (SR) to this region. They are limited to measurements which do not make use of the time structure inherent in SR. Comparisons of SR with conventional sources suggests that the greatest improvements will be realized in the far and vacuum ultraviolet regions--wavelengths less than about 300 nm. Consideration of the transitions of the valence electrons of most organic and biologically important materials indicate that wavelengths less than about 120 nm will not be especially informative. In addition, spectroscopic experiments at wavelengths less than 105 nm become more difficult because of the loss of window materials and surfaces with high normal incidence reflectance. The characteristic visible and ultraviolet absorption bands of proteins, nucleic acids and sugars are reviewed. Important spectroscopic techniques such as absorption, natural and magnetic circular dichroism, fluorescence and various fluorescence polarization spectroscopies are described and their potential use in the far and vacuum ultraviolet (120 to 300 nm) using synchrotron sources is discussed.

  2. Effects of solar ultraviolet radiation on antarctic phytoplankton during springtime ozone depletion

    International Nuclear Information System (INIS)

    In recent years, much attention has been given to the formation of the seasonal ozone open-quotes holeclose quotes over Antarctica, with the concomitant increase in ultraviolet-B [UV-B, 280-320-nanometer (nm)] radiation levels. The enhanced UV-B radiation can be very damaging to biological systems and has been shown to cause a significant decrease in rates of primary production. This paper describes the impact of open-quotes normalclose quotes ultraviolet radiation (UVR), as well as enhanced UV-B radiation, on natural assemblages of phytoplankton as well as on just the nanoplankton fraction cells less than 20 micrometers (μm). The studies also included estimation of the impact of UVR as influenced by the taxonomic composition of the phytoplankton and the mitigating effect of cellular UV-absorbing compounds. All studies were carried out at Palmer Station (64.7 degrees S 64.1 degrees W) on Anvers Island from early October to the end of December 1993. This period provided excellent opportunities to document the impact of enhanced UV-B radiation on phytoplankton because the ozone hole was very well developed over Palmer Station in the month of October; column ozone concentrations ranged from 140 to 220 Dobson units (DU). 10 refs, 3 figs

  3. Effects of ultraviolet radiation on saccharomyces uvarum metabolism

    International Nuclear Information System (INIS)

    The objective of this study was to measure the effect of UV radiation on the metabolism of Saccharomcyes uvarum in wort used in beer production. Pure yeast cultures were exposed to a Westinghouse G8T5 germicidal lamp for 10, 20, 30 and 40 minutes and added to fresh wort. The cultures were allowed to ferment for 96 hours at 130 C and fermentation products were assayed at 24 hour intervals and analyzed on a SCABA BEER ANALYZER. Metabolic parameters measured were balling, alcohol and cell count. Percent alcohol (V/V %) increased significantly at all exposures, but as the UV dosage increased, alcohol levels showed a significant decline with longer exposures. The assimilation of sugars or balling levels dropped at each exposure level among samples. The ability for the yeast to assimilate sugars decreased as UV exposure was increased although pitching rates fluctuated. (Pitching rates are the cell count readings at inoculation). None of the samples showed a logarithmic growth pattern, except for the controls which did not exhibit a lag phase. All other samples decreased cell counts as exposure levels increased, without peaks. Substrate availability was not a factor in the metabolism of Saccharomyces uvarum. Cell count levels at each exposure could have possibly affected the metabolic parameters because of excessive cell killing. Viabilities at the exposure levels studied show that the number of live cells available for nutrient uptake was lower at each level. However, the peak levels of the parameters measured were very close to the controls. Although the availability of cells was low, metabolic rates could have been altered by the UV light

  4. Ionizing and ultraviolet radiation enhances the efficiency of DNA mediated gene transfer in vitro

    International Nuclear Information System (INIS)

    The enhancement effects of ionizing and non-ionizing radiation on the efficiency of DNA mediated gene transfer were studied. Confluent Rat-2 cells were transfected with purified SV40 viral DNA, irradiated with either X-rays or ultraviolet, trypsinized, plated, and assayed for the formation of foci on Rat-2 monolayers. Both ionizing and ultraviolet radiation enhanced the frequency of A-gene transformants/survivor compared to unirradiated transfected cells. These enhancements were non-linear and dose dependent. A recombinant plasmid, pOT-TK5, was constructed that contained the SV40 virus A-gene and the Herpes Simplex virus (HSV) thymidine kinase (TK) gene. Confluent Rat-2 cells transfected with pOT-TK5 DNA and then immediately irradiated with either X-rays or 330 MeV/amu argon particles at the Berkeley Bevalac showed a higher frequency of HAT+ colonies/survivor than unirradiated transfected cells. Rat-2 cells transfected with the plasmid, pTK2, containing only the HSV TK-gene were enhanced for TK-transformation by both X-rays and ultraviolet radiation. The results demonstrate that radiation enhancement of the efficiency of DNA mediated gene transfer is not explained by increased nuclear uptake of the transfected DNA. Radiation increases the competence of the transfected cell population for genetic transformation. Three models for this increased competence are presented. The targeted integration model, the inducible recombination model, the partition model, and the utilization of DNA mediated gene transfer for DNA repair studies are discussed. 465 references

  5. Ionizing and ultraviolet radiation enhances the efficiency of DNA mediated gene transfer in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Perez, C.F.

    1984-08-01

    The enhancement effects of ionizing and non-ionizing radiation on the efficiency of DNA mediated gene transfer were studied. Confluent Rat-2 cells were transfected with purified SV40 viral DNA, irradiated with either X-rays or ultraviolet, trypsinized, plated, and assayed for the formation of foci on Rat-2 monolayers. Both ionizing and ultraviolet radiation enhanced the frequency of A-gene transformants/survivor compared to unirradiated transfected cells. These enhancements were non-linear and dose dependent. A recombinant plasmid, pOT-TK5, was constructed that contained the SV40 virus A-gene and the Herpes Simplex virus (HSV) thymidine kinase (TK) gene. Confluent Rat-2 cells transfected with pOT-TK5 DNA and then immediately irradiated with either X-rays or 330 MeV/amu argon particles at the Berkeley Bevalac showed a higher frequency of HAT/sup +/ colonies/survivor than unirradiated transfected cells. Rat-2 cells transfected with the plasmid, pTK2, containing only the HSV TK-gene were enhanced for TK-transformation by both X-rays and ultraviolet radiation. The results demonstrate that radiation enhancement of the efficiency of DNA mediated gene transfer is not explained by increased nuclear uptake of the transfected DNA. Radiation increases the competence of the transfected cell population for genetic transformation. Three models for this increased competence are presented. The targeted integration model, the inducible recombination model, the partition model, and the utilization of DNA mediated gene transfer for DNA repair studies are discussed. 465 references.

  6. Ultraviolet Radiation and the Photobiology of Earth's Early Oceans

    Science.gov (United States)

    Cockell, Charles S.

    2000-10-01

    During the Archean era (3.9-2.5 Ga ago) the earth was dominated by an oceanic lithosphere. Thus, understanding how life arose and persisted in the Archean oceans constitutes a major challenge in understanding early life on earth. Using a radiative transfer model of the late Archean oceans, the photobiological environment of the photic zone and the surface microlayer is explored at the time before the formation of a significant ozone column. DNA damage rates might have been approximately three orders of magnitude higher in the surface layer of the Archean oceans than on the present-day oceans, but at 30 m depth, damage may have been similar to the surface of the present-day oceans. However at this depth the risk of being transported to surface waters in the mixed layer was high. The mixed layer may have been inhabited by a low diversity UV-resistant biota. But it could have been numerically abundant. Repair capabilities similar to Deinococcus radiodurans would be sufficient to survive in the mixed layer. Diversity may have been greater in the region below the mixed layer and above the light compensation point corresponding to today's `deep chlorophyll maximum'. During much of the Archean the air-water interface was probably an uninhabitable extreme environment for neuston. The habitability of some regions of the photic zone is consistent with the evidence embodied in the geologic record, which suggests an oxygenated upper layer in the Archean oceans. During the early Proterozoic, as ozone concentrations increased to a column abundance above 1 × 10^17 cm^-2, UV stress would have been reduced and possibly a greater diversity of organisms could have inhabited the mixed layer. However, nutrient upwelling from newly emergent continental crusts may have been more significant in increasing total planktonic abundance in the open oceans and coastal regions than photobiological factors. The phohobiological environment of the Archean oceans has implications for the potential

  7. Response of tomato to radiation intensity and air temperature under plastic-house ultraviolet protection

    International Nuclear Information System (INIS)

    Enhance of ultraviolet radiation intensity on the earth surface affected by ozon depletion on stratospheric layer cause changing on the response of plant to radiation quality. One technique for reducing photo destructive UV radiation is micro climate modification by using mulch and plastic-cover UV protection. So that, growth and yield of plant can be optimalized. This research designed an experiment to find out the effect of two kinds of plastic-cover, UV plastic and conventional plastic, on microclimate condition and tomato performance under plastic-house. The result of this research described that mulch and plastic cover can modify radiation and air temperature under plastics-house, but it can not improve growth and yield of the tomato

  8. Ultraviolet-B radiation alters phenolic salicylate and flavenoid composition of Populus trichocarpa leaves

    Energy Technology Data Exchange (ETDEWEB)

    Warren, J. M. [USDA Forest Service, Forestry Science Laboratory, Corwallis, OR (United States); Bassman, J. H. [Washington State Univ., Dept. of Natural Resources Sciences, Pullman, WA (United States); Fellman, J. K.; Mattinson, D. S. [Washington State Univ., Dept. of Horticulture and Landscape Architecture, Pullman, WA (United States); Eigenbrode, S. [Idaho Univ., Dept. of Plant, Soil and Entomological Sciences, Moscow, ID (United States)

    2003-06-01

    Foliar phenolic composition of field- and greenhouse-grown black cottonwood was studied by subjecting samples to near zero, ambient and twice-ambient concentrations of biologically effective ultraviolet-B radiation. Phenolic compounds were extracted after three months, separated by liquid chromatography and identified and quantified by diode-array spectrometry and mass spectrometry. Phenolic compounds that were found to have increased in response to UV-B radiation were flavonoids, although increasing the level of radiation to ambient and twice ambient levels did not result in further flavonoid accumulation in either greenhouse or field samples. There was, however, an increase in salicortin, a non-flavonoid glycoside, and a salicylates that is important in plant-herbivore-predator relationships. It was concluded that enhanced solar UV-B radiation has the capacity to significantly alter trophic structure in some ecosystems by stimulating specific phenolic compounds. 74 refs., 1 tab., 6 figs.

  9. The role of ultraviolet radiation in the pathogenesis of pterygia (Review).

    Science.gov (United States)

    Zhou, Wei-Ping; Zhu, Yuan-Fang; Zhang, Bei; Qiu, Wen-Ya; Yao, Yu-Feng

    2016-07-01

    Pterygium is a common ophthalmic disease affecting humans only. Extensive epidemiological data have demonstrated a causative effect of chronic ultraviolet (UV) radiation on pterygia. Progress has been made in determining the origin of pterygia, their nasal predilection and wing‑shaped appearance, and the roles of UV radiation in the initiation and the development of pterygia. In the present review, the current understanding of the involvement of UV radiation in the pathogenesis of pterygia is summarized. This involvement includes the alteration of limbal stem cells and fibroblasts that contribute to the initiation of pterygia and the induction of various pro‑inflammatory cytokines, growth factors and matrix metalloproteinases that promote the progression of pterygia. Further elucidation of the roles of UV radiation in the pathogenesis of pterygia may help to encourage individuals at risk of developing pterygia to take preventive measures and aid researchers in the development of novel targeted therapeutic agents to treat pterygia. PMID:27176595

  10. Ultraviolet-B radiation causes shade-type ultrastructural changes in Brassica napus

    International Nuclear Information System (INIS)

    Cell and chloroplast structural changes in palisade cells from mature leaves of Brassica napus L. cv. Paroll were quantified following exposure of plants to enhanced ultraviolet-B (280–320 nm; 13 kJ m−2 day−1 biologically effective UV-B) radiation at two different levels of photosynthetically active radiation (PAR, 400–700 nm; 200 and 700 μmol m−2 s−1). Short-term changes in leaf ultrastructure after 30 min and longer term changes after one day and one week were analyzed using stereological techniques incorporating light and electron microscopy and mathematical reconstruction of a mean cell for each sample. Ultraviolet-B together with either relatively high or low PAR resulted in cell structural changes resembling those typical of plants under shade conditions, with the most marked response occurring after 30 min of UV-B radiation. The ultrastructural changes at the cellular level were generally similar in both the relatively high and low PAR plus UV-B radiation treatments. The surface areas of all three thylakoid types, the appressed, non-appressed and margin thylakoids increased in the palisade tissue under supplemental UV-B irradiation. Although the appressed and non-appressed thylakoids increased in surface area, they did not increase equally, leaving open the possibility that the two thylakoid types have independent regulatory systems or different sensitivity to UV-B radiation. Increased thylakoid packing (mm2 thylakoid membrane per mm2 leaf surface) in UV-B-exposed plants may increase the statistical probability of photon interception. An increased level of UV-absorbing pigments after one week of supplemental UV-B radiation did not prevent or significantly ameliorate UV effects. Our data supported the assumption that UV-B radiation may have a regulatory role besides damaging effects and that an increased UV-B environment will likely increase this regulatory influence of UV-B radiation. (author)

  11. Conversion of far ultraviolet to visible radiation: absolute measurements of the conversion efficiency of tetraphenyl butadiene

    Science.gov (United States)

    Vest, Robert E.; Coplan, Michael A.; Clark, Charles W.

    Far ultraviolet (FUV) scintillation of noble gases is used in dark matter and neutrino research and in neutron detection. Upon collisional excitation, noble gas atoms recombine into excimer molecules that decay by FUV emission. Direct detection of FUV is difficult. Another approach is to convert it to visible light using a wavelength-shifting medium. One such medium, tetraphenyl butadiene (TPB) can be vapor-deposited on substrates. Thus the quality of thin TPB films can be tightly controlled. We have measured the absolute efficiency of FUV-to-visible conversion by 1 μm-thick TPB films vs. FUV wavelengths between 130 and 300 nm, with 1 nm resolution. The energy efficiency of FUV to visible conversion varies between 1% and 5%. We make comparisons with other recent results. Work performed at the NIST SURF III Synchrotron Ultraviolet Radiation Facility,.

  12. Ultraviolet-b radiation effects on water relations, leaf development, and photosynthesis in droughted pea plants

    International Nuclear Information System (INIS)

    The effects of ultraviolet-B (UV-B) radiation on water relations leaf development and gas-exchange characteristics in pea (Pisum sativum L. cv Meteor) plants subjected to drought were investigated. Plants grown throughout their development under a high irradiance of UV-B radiation (0.63 W m-2) were compared with those grown without UV-B radiation and after 12 d one-half of the plants were subjected to 24 d of drought that resulted in mild water stress. UV-B radiation resulted in a decrease of adaxial stomatal conductance by approximately 65%, increasing stomatal limitation of CO2 uptake by 10 to 15%. However, there was no loss of mesophyll light saturated photosynthetic activity. Growth in UV-B radiation resulted in large reductions of leaf area and plant biomass which were associated with a decline in leaf cell numbers and cell division UV-B radiation also inhibited epidermal cell expansion of the exposed surface of leaves. There was an interaction between UV-B radiation and drought treatments: UV-B radiation both delayed and reduced the severity of drought stress through reductions in plant water-loss rates, stomatal conductance, and leaf area

  13. The potential sensitivity of tropical plants to increased ultraviolet-B radiation

    International Nuclear Information System (INIS)

    Little is known concerning the impact of stratospheric ozone depletion and increasing ultraviolet (UV)-B radiation on the phenology and growth of tropical plants. This is because, ostensibly, tropical plants are already exposed to relatively high levels of UV-B radiation (relative to a temperate environment) and should, therefore, possess a greater degree of tolerance to increased UV-B radiation. In this brief review I hope to show that, potentially, direct and indirect effects on photosynthesis, assimilate partitioning, phenology and biomass could occur in both tropical crops (e.g. cassava, rice) and native species (e.g. Cecropia obtusifolia (Bertol. Fl)., Tetramolopium humile (Gray), Nana sandwicensis L.). However, it should be noted that differences in sensitivity to UV-B radiation can be related to experimental conditions, and care should be taken to ensure that the quantity and quality of background solar radiation remains at near ambient conditions. Nevertheless, by integrating current and past studies on the impact of UV-B radiation on tropical species, I hope to be able to demonstrate that photosynthesis, morphology and growth in tropical plants could be directly affected by UV-B radiation and that UV-B radiation may be a factor in species and community dynamics in natural plant populations in the tropics

  14. Effects of long-wavelength ultraviolet (UV-A) radiation on the growth of Anacystis Nidulans

    International Nuclear Information System (INIS)

    The growth of Anacystis nidulans cells which had been grown under visible light only (>390 nm) was suppressed by long-wavelength ultraviolet (UV-A, 320-390 nm) radiation. The growth resumed after 24 h. Cells grown under UV-A supplemented light contained less chlorophyll and phycocyanin and more carotenoid than control cells. The finding that UV-A radiation inhibited the rate of delta-aminolevulinic acid synthesis indicated that the decreases in the photosynthetic pigments were mainly due to the inhibition of their biosynthesis rather than to photodestruction of pigments by UV-A radiation. The primary cause of the inhibitory effects seems to be the inhibition of the photosynthetic process which can be measured as the rho-benzoquinone Hill reaction. Previous exposure to UV-A radiation conferred some resistance on the cells to this inhibitory radiation. Thus UV-A radiation itself may activate a system that repairs damage caused by UV-A radiation and/or protects against the radiation. (author)

  15. Process for producing a collagen web for a transparent artificial cornea and a contact lens by irradiation with ultraviolet or gamma rays

    International Nuclear Information System (INIS)

    A process for producing a collagen web for use as an artificial cornea and a contact lens is provided by irradiating an acid soluble collagen web or a swelled collagen web with ultraviolet rays or gamma radiation. Cross-linking is introduced into the molecules forming a noncrystalline portion of the collagen to minimize nonuniformity of construction. In embodiments, the collagen, dissolved in a diluted hydrochloric acid or acetic acid aqueous solution at a concentration of about 0.5% to 1%(pH 2-4), is poured into a suitable container for producing and drying a web. The obtained web is neutralized with ammoniac water or vapor and is washed completely. The web is dipped in a dilute hydrochloric acid or acetic acid aqueous solution (pH 2-4) to well and then irradiated. Cross-linking is introduced, followed by further neutralization with ammoniac vapor. Finally the web is washed, air-dried or kept in water. Alternately, the above 0.5%-1% collagen solution is irradiated to gelatinize it after the oxygen dissolved in the solution is substituted with nitrogen. The irradiated web is neutralized with ammoniac water or vapor, and then washed, air-dried or kept in water. In one example, 0.58% collagen hydrochloric acid solution was poured into a methylmethacrylate box and was air-dried to form a web 0.03mm in thickness. The web was neutralized with ammoniac vapor for 24 hours and dipped to swell in a 0.01N HCl solution for 1 minute. The opposite sides of the web were irradiated with UV-rays at 15W. (Iwakiri, K.)

  16. Photochemical responses of three marine phytoplankton species exposed to ultraviolet radiation and increased temperature: role of photoprotective mechanisms.

    Science.gov (United States)

    Halac, S R; Villafañe, V E; Gonçalves, R J; Helbling, E W

    2014-12-01

    We carried out experiments using long-term (5-7 days) exposure of marine phytoplankton species to solar radiation, in order to assess the joint effects of ultraviolet radiation (UVR) and temperature on the photochemical responses and photoprotective mechanisms. In the experiments, carried out at Atlantic coast of Patagonia (43°18.7'S; 65°2.5'W) in spring-summer 2011, we used three species as model organisms: the dinoflagellate Prorocentrum micans, the chlorophyte Dunaliella salina and the haptophyte Isochrysis galbana. They were exposed under: (1) two radiation quality treatments (by using different filters): P (PAR, >400 nm) and PAB (PAR+UV-A+UV-B, >280 nm); (2) two radiation intensities (100% and 50%) and (3) two experimental temperatures: 18 °C and 23 °C during summer and 15 °C and 20 °C in spring experiments, simulating a 5 °C increase under a scenario of climate change. In addition, short-term (4h) artificial radiation exposure experiments were implemented to study vertical migration of cells pre- and non-acclimated to solar radiation. We observed species-specific responses: P. micans displayed a better photochemical performance and a lower inhibition induced by UVR than D. salina and I. galbana. In accordance, P. micans was the only species that showed a synthesis of UV-absorbing compounds (UVACs) during the experiment. On the other hand, non-photochemical quenching (NPQ) was activated in D. salina at noon throughout the exposure, while I. galbana did not show a regular NPQ pattern. This mechanism was almost absent in P. micans. Regarding vertical migration, I. galbana showed the most pronounced displacement to deepest layers since the first two hours of exposure in pre- and non-acclimated cells, while only non-acclimated D. salina cells moved to depth at the end of the experiment. Finally, temperature partially counteracted solar radiation inhibition in D. salina and I. galbana, whereas no effect was observed upon P. micans. In particular, significant

  17. A novel facility for ageing materials with narrow-band ultraviolet radiation exposure

    International Nuclear Information System (INIS)

    A facility for exploring wavelength dependencies in ultraviolet (UV) radiation induced degradation in materials has been designed and constructed. The device is essentially a spectrograph separating light from a lamp to spectrally resolved UV radiation. It is based on a 1 kW xenon lamp and a flat-field concave holographic grating 10 cm in diameter. Radiation at the wavelength range 250-500 nm is dispersed onto the sample plane of 1.5 cm in height and 21 cm in width. The optical performance of the device has been characterized by radiometric measurements. Using the facility, test samples prepared of regular newspaper have been irradiated from 1 to 8 h. Color changes on the different locations of the aged samples have been quantified by color measurements. Yellowness indices computed from the color measurements demonstrate the capability of the facility in revealing wavelength dependencies of the material property changes in reasonable time frames.

  18. Effect of Natural Intensities of Visible and Ultraviolet Radiation on Epidermal Ultraviolet Screening and Photosynthesis in Grape Leaves

    Czech Academy of Sciences Publication Activity Database

    Kolb, Ch.; Kasel, M.; Kopecký, Jiří; ZOTZ, G.; Riederer, M.; Pfundel, E.

    č. 127 (2001), s. 863-875. ISSN 0032-0889 Institutional research plan: CEZ:AV0Z5020903 Keywords : natural intensities * visible * ultraviolet Subject RIV: CE - Biochemistry Impact factor: 5.105, year: 2001

  19. Current and future impacts of ultraviolet radiation on the terrestrial carbon balance

    Institute of Scientific and Technical Information of China (English)

    W. Kolby SMITH; Wei GAO; Heidi STELTZER

    2009-01-01

    One of the most documented effects of human activity on our environment is the reduction of stratospheric ozone resulting in an increase of biologically harmful ultraviolet (UV) radiation. In a less predictable manner, UV radiation incident at the surface of the earth is expected to be further modified in the future as a result of altered cloud condition, atmospheric aerosol concentration, and snow cover. Although UV radiation comprises only a small fraction of the total solar radiation that is incident at the earth's surface, it has the greatest energy per unit wavelength and, thus, the greatest potential to damage the biosphere. Recent investigations have highlighted numerous ways that UV radiation could potentially affect a variety of ecological processes, including nutrient cycling and the terrestrial carbon cycle. The objectives of the following literature review are to summarize and synthesize the available information relevant to the effects of UV radiation and other climate change factors on the terrestrial carbon balance in an effort to highlight current gaps in knowledge and future research directions for UV radiation research.

  20. Prediction of Global Solar Radiation in India Using Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    Rajiv Gupta

    2016-06-01

    Full Text Available Increasing global warming and decreasing fossil fuel reserves has necessitated the use of renewable energy resources like solar energy in India. To maximize return on a solar farm, it had to be set up at a place with high solar radiation. The solar radiation values are available only for a small number of places and must be interpolated for the rest. This paper utilizes Artificial Neural Network in interpolation, by obtaining a function with input as combinations of 7 geographical and meteorological parameters affecting radiation, and output as global solar radiation. Data considered was of past 9 years for 13 Indian cities. Low error values and high coefficient of determination values thus obtained, verified that the results were accurate in terms of the original solar radiation data known. Thus, artificial neural network can be used to interpolate the solar radiation for the places of interest depending on the availability of the data.

  1. Effects of ultraviolet-B radiation on plants during mild water stress, 4: The insensitivity of soybean internal water relations to ultraviolet-B radiation

    International Nuclear Information System (INIS)

    The combined effects of ultraviolet-B (UV-B, 280–320 nm) radiation and water stress were investigated on the water relations of greenhouse grown soybean [Glycine max (L.) Merr. cv. Essex]. On a weighted (Caldwell 1971), total daily dose basis, plants received either 0 or 3 000 effective J m2 UV-BBE supplied by filtered FS-40 sunlamps. The latter dose simulated the solar UV-B radiation anticipated at College Park, Maryland, U.S.A. (39°N latitude) in the event that the global stratospheric ozone column is reduced by 25%. Plants were either well-watered or preconditioned by drought stress cycles. Diurnal measurements of water potential and stomatal conductance were made on the youngest fully expanded leaf. Various internal water relations parameters were determined for detached leaves. Plants were monitored before, during and after water stress. There were no significant differences in leaf water potential or stomatal conductance between treatments before plants were preconditioned to water stress. However, drought stress resulted in significantly lower midday and afternoon leaf water potentials and lower leaf conductances as compared to well-watered plants. UV-B radiation had no additional effect on leaf water potential; however, UV did result in lower leaf conductances in plants preconditioned to water stress. Turgid weight:dry weight ratio, elastic modulus, bound water and relative water content were unaffected by UV-B radiation. Osmotic potentials at full and zero turgor were significantly lower in the drought stressed treatments as compared to well-watered plants. (author)

  2. Bystander effects in UV-induced genomic instability: Antioxidants inhibit delayed mutagenesis induced by ultraviolet A and B radiation

    Directory of Open Access Journals (Sweden)

    Dahle Jostein

    2005-01-01

    Full Text Available Abstract Background Genomic instability is characteristic of many types of human cancer. Recently, we reported that ultraviolet radiation induced elevated mutation rates and chromosomal instability for many cell generations after ultraviolet irradiation. The increased mutation rates of unstable cells may allow them to accumulate aberrations that subsequently lead to cancer. Ultraviolet A radiation, which primarily acts by oxidative stress, and ultraviolet B radiation, which initially acts by absorption in DNA and direct damage to DNA, both produced genomically unstable cell clones. In this study, we have determined the effect of antioxidants on induction of delayed mutations by ultraviolet radiation. Delayed mutations are indicative of genomic instability. Methods Delayed mutations in the hypoxanthine phosphoribosyl transferase (hprt gene were detected by incubating the cells in medium selectively killing hprt mutants for 8 days after irradiation, followed by a 5 day period in normal medium before determining mutation frequencies. Results The UVB-induced delayed hprt mutations were strongly inhibited by the antioxidants catalase, reduced glutathione and superoxide dismutase, while only reduced glutathione had a significant effect on UVA-induced delayed mutations. Treatment with antioxidants had only minor effects on early mutation frequenies, except that reduced glutathione decreased the UVB-induced early mutation frequency by 24 %. Incubation with reduced glutathione was shown to significantly increase the intracellular amount of reduced glutathione. Conclusion The strong effects of these antioxidants indicate that genomic instability, which is induced by the fundamentally different ultraviolet A and ultraviolet B radiation, is mediated by reactive oxygen species, including hydrogen peroxide and downstream products. However, cells take up neither catalase nor SOD, while incubation with glutathione resulted in increased intracellular levels of

  3. Measurement of the solar ultraviolet radiation at ground level in Bangi, Malaysia

    International Nuclear Information System (INIS)

    Understanding the amount of ultraviolet (UV) radiation received by human, plant, and animal organisms near the earth’s surface is important to a wide range of fields such as cancer research, agriculture and forestry. The solar ultraviolet spectral irradiance at ground level was measured using the Avantes spectrometer for the period of January to March 2014 at Bangi (2°55´N, 101°46´E, 50 m above sea level) in Malaysia. These data were used to estimate the diurnal variation of UV irradiance (300 – 400 nm). The maximum irradiance of UV radiation was 45 W m−2 on horizontal surface. The maximum irradiance of UV received in the local noon time, and the minimum values of UV irradiance was received in the local morning time. It is found a bigger value of UV radiation was observed on clear sky in January. The estimation of daily flux average of UV irradiance was (921± 91) kJ m−2

  4. Inactivation of Cryptosporidium parvum oocysts using medium- and low-pressure ultraviolet radiation.

    Science.gov (United States)

    Craik, S A; Weldon, D; Finch, G R; Bolton, J R; Belosevic, M

    2001-04-01

    The effect of ultraviolet radiation from low- and medium-pressure mercury arc lamps on Cryptosporidium parvum oocysts was studied using a collimated beam apparatus. Experiments were conducted using parasites suspended in both filtered surface water and phosphate buffered laboratory water. Inactivation of oocysts was measured as reduction in infectivity using a CD-1 neonatal mouse model and was found to be a non-linear function of UV dose over the range of germicidal doses tested (0.8-119 mJ/cm2). Oocyst inactivation increased rapidly with UV dose at doses less than 25 mJ/cm2 with two and three log-units inactivation at approximately 10 and 25 mJ/cm2, respectively. The cause of significant leveling-off and tailing in the UV inactivation curve at higher doses was not determined. Maximum measured oocyst inactivation ranged from 3.4 to greater than 4.9 log-units and was dependent on different batches of parasites. Water type and temperature, the concentration of oocysts in the suspension, and the UV irradiance did not have significant impacts on oocyst inactivation. When compared on the basis of germicidal UV dose, the oocysts were equally sensitive to low- and medium-pressure UV radiation. With respect to Cryptosporidium, both low- and medium-pressure ultraviolet radiation are attractive alternatives to conventional chemical disinfection methods in drinking water treatment. PMID:11317885

  5. Ambient ultraviolet radiation induces protective responses in soybean but does not attenuate indirect defense

    International Nuclear Information System (INIS)

    We investigated the effects of ambient ultraviolet (UV) radiation on (i) the performance and chemistry of soybean plants, (ii) the performance of Spodoptera frugiperda and (iii) the foraging behavior of the herbivore's natural enemy Cotesia marginiventris which exploits herbivore-induced plant volatiles (VOC) for host location. The accumulation of protective phenolics was faster in plants receiving ambient UV than in controls exposed to sun light lacking UV. Accordingly, isorhamnetin- and quercetin-based flavonoids were increased in UV exposed plants. No UV effects were found on the performance and feeding behavior of S. frugiperda. Herbivore-damaged plants emitted the same VOC when grown under ambient or attenuated UV for 5, 10 or 30 days. Consequently, C. marginiventris was attracted but did not discriminate between exposed and unexposed soybeans. In summary, ambient UV radiation affected soybean morphology and physiology but did not destabilize interactions between trophic levels. - Ambient ultraviolet radiation does not alter induced VOC emission in soybean and thus host location of the parasitoid Cotesia marginiventris remains effective

  6. Laser Desorption Postionization Mass Spectrometry of Antibiotic-Treated Bacterial Biofilms using Tunable Vacuum Ultraviolet Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Gasper, Gerald L; Takahashi, Lynelle K; Zhou, Jia; Ahmed, Musahid; Moore, Jerry F; Hanley, Luke

    2010-08-04

    Laser desorption postionization mass spectrometry (LDPI-MS) with 8.0 ? 12.5 eV vacuum ultraviolet synchrotron radiation is used to single photon ionize antibiotics andextracellular neutrals that are laser desorbed both neat and from intact bacterial biofilms. Neat antibiotics are optimally detected using 10.5 eV LDPI-MS, but can be ionized using 8.0 eV radiation, in agreement with prior work using 7.87 eV LDPI-MS. Tunable vacuum ultraviolet radiation also postionizes laser desorbed neutrals of antibiotics and extracellular material from within intact bacterial biofilms. Different extracellular material is observed by LDPI-MS in response to rifampicin or trimethoprim antibiotic treatment. Once again, 10.5 eV LDPI-MS displays the optimum trade-off between improved sensitivity and minimum fragmentation. Higher energy photons at 12.5 eV produce significant parent ion signal, but fragment intensity and other low mass ions are also enhanced. No matrix is added to enhance desorption, which is performed at peak power densities insufficient to directly produce ions, thus allowing observation of true VUV postionization mass spectra of antibiotic treated biofilms.

  7. Measurement of the solar ultraviolet radiation at ground level in Bangi, Malaysia

    Energy Technology Data Exchange (ETDEWEB)

    Aljawi, Ohoud; Gopir, Geri; Duay, Abdul Basit [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia. ohoud-aljawi@hotmail.com (Malaysia)

    2015-04-24

    Understanding the amount of ultraviolet (UV) radiation received by human, plant, and animal organisms near the earth’s surface is important to a wide range of fields such as cancer research, agriculture and forestry. The solar ultraviolet spectral irradiance at ground level was measured using the Avantes spectrometer for the period of January to March 2014 at Bangi (2°55´N, 101°46´E, 50 m above sea level) in Malaysia. These data were used to estimate the diurnal variation of UV irradiance (300 – 400 nm). The maximum irradiance of UV radiation was 45 W m{sup −2} on horizontal surface. The maximum irradiance of UV received in the local noon time, and the minimum values of UV irradiance was received in the local morning time. It is found a bigger value of UV radiation was observed on clear sky in January. The estimation of daily flux average of UV irradiance was (921± 91) kJ m{sup −2}.

  8. Daily and annual variations of erythemal ultraviolet radiation in Southwestern Spain

    Directory of Open Access Journals (Sweden)

    A. Serrano

    2006-03-01

    Full Text Available The potential danger of ultraviolet (UV radiation and its increasing levels at the Earth's surface due to ozone depletion have demanded worldwide representative measurements of UV radiation. This study presents four and one-half years of original records of high temporal resolution ultraviolet erythemal radiation (UVER measured in Badajoz, Spain. Its principal aim is to statistically characterize the UVER magnitude and temporal variations, but also to address the interesting special cases of cloud-free and cloudy skies. In particular, the study reports reliable values of fundamental statistical indices, which can serve as relevant values for comparison with other studies and model results. Moreover, the daily and annual evolution of the main central moments of the distribution function are analyzed and interpreted in terms of the forcing and attenuation sources.

    The analysis focuses on two different temporal scales: hourly and daily values. Integrated hourly and daily data allow for the study of daily and annual variations of the fundamental statistical indices. All of them exhibit high symmetry with respect to solar noon and to certain dates near summer and winter solstices. The analysis shows the great influence of cloudiness in the distribution of UVER values. Thus, both daily and hourly UVER data present a slightly asymmetrical, left tailed, mesokurtic distribution for all months, except for summer, when the lack of clouds produces a leptokurtic distribution which is skewed to the left.

  9. TL and LOE dosimetric evaluation of diamond films exposed to beta and ultraviolet radiation

    International Nuclear Information System (INIS)

    The diamond possesses a privileged position regarding other materials of great technological importance. Their applications go from the optics, microelectronics, metals industry, medicine and of course as dosemeter, in the registration and detection of ionizing and non ionizing radiation. In this work the results of TL/LOE obtained in two samples of diamond of 10 μm thickness grown by the chemical vapor deposition method (CVD) assisted by microwave plasma. The films were deposited in a silicon substrate (001) starting from a mixture of gases composed of CH4/H2 and 750 ppm of molecular nitrogen as dopant. The samples were exposed to beta radiation (Sr90/ Y90) and ultraviolet, being stimulated later on thermal (TL) and optically (LOE) to evaluate their dosimetric properties. The sample without doping presented high response TL/LOE to the ultraviolet and beta radiation. The TL glow curve of the sample without doping showed two TL peaks with second order kinetics in the range of 520 to 550 K, besides a peak with first order kinetics of more intensity around 607 K. The TL efficiency of the non doped sample is bigger than the doped with nitrogen; however the LOE efficiency is similar in both samples. The results indicate that the CVD diamond possesses excellent perspectives for dosimetric applications, with special importance in radiotherapy due to it is biologically compatible with the human tissue. (Author)

  10. Photoreactivation of ultraviolet radiation-induced release of arachidonic acid from marsupial cells

    International Nuclear Information System (INIS)

    Exposure of an established marsupial cell line, PtK2 (Potorous tridactylus), to ultraviolet radiation (UVR) from an FS-40 sunlamp (280-400 nm) resulted in a fluence-dependent release of radiolabeled arachidonic acid (AA) from cell membrane. Post-UVR, but not pre-UVR, exposure to photoreactivating light reversed UVR-induced pyrimidine dimers in DNA and suppressed the UVR-induced release of AA. These data indicate that DNA damage contributes to the release of AA from membrane phospholipids. (author)

  11. Photoreactivation of ultraviolet radiation-induced release of arachidonic acid from marsupial cells

    Energy Technology Data Exchange (ETDEWEB)

    Kaleta, E.W.; Applegate, L.A.; Ley, R.D. (Lovelace Foundation for Medical Education and Research, Albuquerque, NM (United States))

    1991-11-01

    Exposure of an established marsupial cell line, PtK{sub 2} (Potorous tridactylus), to ultraviolet radiation (UVR) from an FS-40 sunlamp (280-400 nm) resulted in a fluence-dependent release of radiolabeled arachidonic acid (AA) from cell membrane. Post-UVR, but not pre-UVR, exposure to photoreactivating light reversed UVR-induced pyrimidine dimers in DNA and suppressed the UVR-induced release of AA. These data indicate that DNA damage contributes to the release of AA from membrane phospholipids. (author).

  12. Arsenic-induced enhancement of ultraviolet radiation carcinogenesis in mouse skin: a dose-response study.

    OpenAIRE

    Burns, Fredric J.; Uddin, Ahmed N.; Wu, Feng; Nádas, Arthur; Rossman, Toby G.

    2004-01-01

    The present study was designed to establish the form of the dose-response relationship for dietary sodium arsenite as a co-carcinogen with ultraviolet radiation (UVR) in a mouse skin model. Hairless mice (strain Skh1) were fed sodium arsenite continuously in drinking water starting at 21 days of age at concentrations of 0.0, 1.25, 2.5, 5.0, and 10 mg/L. At 42 days of age, solar spectrum UVR exposures were applied three times weekly to the dorsal skin at 1.0 kJ/m2 per exposure until the experi...

  13. Fluence rate or cumulative dose? : Vulnerability of larval northern pike (Esox lucius) to ultraviolet radiation

    OpenAIRE

    Vehniäinen, Eeva-Riikka; Häkkinen, Jani; Oikari, Aimo

    2007-01-01

    Newly hatched larvae of northern pike were exposed in the laboratory to four fluence rates of ultraviolet radiation (UVR; 290–400 nm) over three different time periods, resulting in total doses ranging from 3.0 ± 0.2 to 63.0 ± 4.4 kJ·m−2. Mortality and behavior of the larvae were followed for 8–12 days, and growth measured at the end of the experiment. Also, the principle of reciprocity—that the UVR-induced mortality depends on the cumulative dose, independent of fluence rate—was tested. Flue...

  14. Destruction of pollutants in water with ozone in combination with ultraviolet radiation. 2. Natural trihalomethane precursors

    International Nuclear Information System (INIS)

    The simultaneous application of ozone and ultraviolet radiation is appreciably more effective than ozone alone for the destruction of THM precursors in water from two southern U.S. surface-water sources. A mechanism is suggested that involves the destruction of a precursor initially present and the parallel formation and subsequent destruction of a secondary precursor from the natural organic matrix. From each source water the secondary precursor is apparently resistant to oxidation with ozone alone but is more readily destroyed by O3/UV treatment

  15. Assessment of the human health impact of changes in ultraviolet radiation

    International Nuclear Information System (INIS)

    Although several major health effects of ultraviolet radiation (UVR) are established, precise quantification of this effect is difficult. New Zealand has the most southerly located major human population in the world, and has a particular contribution to make to worldwide progress. However, current information on the frequency of the relevant health problems is unsatisfactory. Major developments in research in New Zealand are needed. UVR is an established causal factor for malignant melanoma, other types of skin cancer, cataracts and some other eye problems and has been implicated in some immunological effects. (author). 5 refs

  16. Ultraviolet radiation-induced lipid peroxidation in liposomal membrane: modification by capsaicin

    International Nuclear Information System (INIS)

    Ultraviolet-radiation has been reported to cause lipid peroxidation in the liposomal membrane. In the present study, treatment with capsaicin, (8-methyl-n-vanillyl-6-nonenamide), the pungent principle of red hot pepper, was shown to modify UV-induced lipid peroxidation in the liposomal membrane. Treatment with low doses of capsaicin (less than 0.1 μg/mL of phosphatidyl choline liposome) produced a significant increase in UV-induced lipid peroxidation, while high doses (0.1-0.5 μg/mL of PC liposome) caused a significant decrease of UV-induced peroxidation

  17. Melanoma Surveillance in the US: Melanoma, Ultraviolet Radiation, and Socioeconomic Status

    Centers for Disease Control (CDC) Podcasts

    2011-10-19

    This podcast accompanies the publication of a series of articles on melanoma surveillance in the United States, available in the November supplement edition of the Journal of the American Academy of Dermatology. Chris Johnson, from the Cancer Data Registry of Idaho, discusses analyses examining the relationship between melanoma and two variables at the county level, ultraviolet radiation and socioeconomic status.  Created: 10/19/2011 by National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP).   Date Released: 10/19/2011.

  18. Further evidence of the role of air pollution on solar ultraviolet radiation reaching the ground

    International Nuclear Information System (INIS)

    The influence of photochemical pollution on the ultraviolet radiation reaching the ground is examined. For this purpose, a series of UV-A and UV-B measurements as well as the results of a simple parametric model are compared. It was found that the hypothesis of UV-B depletion is significant at an almost 95 per cent confidence level. It is also indicated that the effect of photochemical pollution on UV-B levels reaching the ground is roughly three times the same effect on UV-A levels. (author)

  19. Exquisite sensitivity of dendritic cells to ultraviolet radiation and temperature changes

    International Nuclear Information System (INIS)

    Recent data suggest that dendritic cells (DC) are the critical passenger leukocytes in allograft rejection. Moreover, previous studies suggest that ultraviolet radiation (UVR) abrogates many in vivo and in vitro immune responses in which DC function as potent accessory cells (AC); however, the mechanism(s) underlying the suppressive effect of UVR on these responses is unclear. To address this mechanism, the hypothesis was tested that loss of DC viability (hence function) accounts for the suppressive effect of UVR on these responses. To this end, in vitro effects of UVR on murine splenic DC viability were addressed using two types of UVR (ultraviolet B [UVB] and ultraviolet C [UVC]) over a UVR dose range of 0-864 J/m2. DC viability was exquisitely sensitive to UVR when compared with other AC populations and UVC was 4-fold more effective in decreasing DC viability than UVB when doses of equal energy were compared. It was found that both UVR types induced marked decreases in DC viability beginning 4-6 hr post-UVR-treatment, that UVR- and non-UVR-induced death were temperature-dependent, and that decreases in DC viability induced by UVR were compatible with interphase death. Our findings indicate that DC are sensitive to temperature changes and exquisitely sensitive to UVR, and suggest that UVR-induced abrogation of murine immune responses is likely attributable to UVR-induced DC death

  20. Study on thermosonication and ultraviolet radiation processes as an alternative to blanching for some fruits and vegetables

    OpenAIRE

    Elisabete M. C. Alexandre; Santos-Pedro, Dora M.; Brandão, Teresa R. S.; Cristina L.M. Silva

    2011-01-01

    The impacts of ultraviolet-C radiation, blanching by heat, and combination of heat/ultrasounds (thermosonication) were studied for Listeria innocua (inoculated) in red bell peppers, total mesophiles in strawberries and total coliforms in watercress, in the temperature range 50–65 °C. Quality attributes such as colour and firmness were studied for all products, and total anthocyanins content was additionally determined for strawberries. Results showed that ultraviolet- ...

  1. Ultraviolet Radiation Exposure and Epidemiological Characteristics among Patients with skin Basal Cell Carcinoma in a National Dermatology Center in Colombia

    International Nuclear Information System (INIS)

    Objective: To describe patients with skin basal cell carcinoma attending a national dermatology center in Colombia, and explore history of exposure to ultraviolet radiation. Methods: A descriptive study was carried out among patients with histological diagnosis of skin basal cell carcinoma. Socio-demographic characteristics, and practices around exposure to ultraviolet radiation were analyzed through clinical examination and clinical history. Results: Average age was 65 years. More than 80% live in the Andean Region of the country. The higher percentage of ultraviolet radiation exposure occurred during school-age (76,4%), and simultaneously the lower rate of protective practices (hat: 8%; long sleeves: 9%; sun blocker: 0%). Countryside labor is the most common cause of labor exposure to ultraviolet radiation (ages under 15: 89%; ages over 30: 48%). In total 22% of cases corresponded to skin photo type III and 53% presented concomitant actinic keratosis. Conclusions: School-age children and countryside workers represent a priority for preventive campaigns, focusing educational activities mostly on schools. There is a need for evaluating risk factors, knowledge, and attitudes related to ultraviolet radiation among the Colombian population.

  2. Effects of ultraviolet radiation on structural components of enveloped RNA viruses

    International Nuclear Information System (INIS)

    The interaction of ultraviolet radiation and virus particles of Western Equine Encephalomyelitis Virus (WEE) and Newcastle Disease Virus (NDV) which have respectively RNA of positive (RNA+) and negative (RNA-) polarity as genomes, was studied using purified particles. The purified virus preparations were irradiated at a range of 1,000 to 6,000 joules per m2 with posterior analysis of their propagation in primary cells cultures of chicken embryos. It could be observed that a radiation dose of 4,500 joules per m2 could induce 109 TCID50 per ml as minimal loss of titer for WEE virus and NDV. The hemagglutination assay was used as a tool for evaluate the alterations caused by UV radiation on the molecular arrangement of virus proteins. Alterations of the virus hemagglutinating activity were only observed when radiation levels higher than 6,000 joules per m2 were used. The results from hemolysis assays showed the importance of the loss of the envelope integrity and the damages to nucleoprotein structures during the inactivation process, when we use radiation doses higher than 6,000 joules per m2. This model of study can increase our comprehension of the radiation effects on the cell physiology and biological components of the cell membranes. (author). 34 refs., 3 figs., 1 tab

  3. Molecular signals in antigen presentation. II. Activation of cytolytic cells in vitro after ultraviolet radiation or combined gamma and ultraviolet radiation treatment of antigen-presenting cells

    International Nuclear Information System (INIS)

    Murine low-density spleen cells have potent antigen-presenting ability in a hapten-specific cytolytic T lymphocyte (CTL) system using the hapten azobenzenearsonate (ABA). Exposure of these cells to 0.33 KJ/m2 of ultraviolet radiation (UVR) after coupling to hapten results in markedly inhibited antigen-presenting function that can be substantially corrected or bypassed by interleukin 1 (IL 1). These results have been interpreted to reflect an inhibition of Lyt-1+ T cell activation by UVR-treated APC. Treatment of these cells sequentially with 1500 rad of γ-radiation (GR) prior to hapten coupling, followed by 0.33 KJ/m2 of UVR radiation after coupling, results in an antigen-resenting defect only minimally improved by IL 1. However, partially purified interleukin 2 (IL 2) can completely bypass or correct this defect. Thus, combined Cr and UVR induces a different or more profound defect in APC function when compared to UVR alone. However, these cells do provide a signal(s) other than hapten necessary for CTL activation because ABA-coupled high density spleen cells do not activate CTL cells, even with the addition of IL 2. Fluorescence-activated cell sorter analysis demonstrates that exposure of these low density spleen cells to GP or UVR results in decreased I-A antigen expression at 24 hr; exposure to both GR and UVR results in a greater decrease in I-A antigen expression at 24 hr than either alone. The addition of nonhapten-coupled low-density APC partially reconstitutes the ability of combined GR/UVR-treated LD-APC to present antigen, and this effect is enhanced by the administration of exogenous IL 1

  4. Physical, biochemical and physiological effects of ultraviolet radiation on Brassica napus and Phaseolus vulgaris

    International Nuclear Information System (INIS)

    In order to follow some of the changes induced by ultraviolet-B (UV-B, 280-320 nm) radiation in Phaseolus vulgaris and Brassica napus, experiments were designed to localize sites of changes in leaves and to correlate some of the physiological and biochemical changes with penetration of UV-B radiation. B.napus was exposed to 8.9 kJ m-2 day-1 biologically effective UV-B radiation (UV-BBE). The penetration of UV-B radiation into the leaf was followed using a quartz fibre optic microprobe. Monochromatic radiation at 310 nm was decreased by ca 50 and 34% in the adaxial and abaxial epidermis, respectively, in plants not exposed to UV-B, whereas the radiation was decreased by ca 70 and 42%, respectively, in the same region in UV-treated plants. Polychromatic radiation showed a wavelength dependent change mainly for the collimated radiation. The results correlated with the distribution of phenolic compounds analysed from 40 μm paradermal leaf sections. The first adaxial section (40μm) contained 35% of the whole leaf sample flavonoid glycosides in control plants, and 66% in UV-treated plants. Hydroxycinnamic acid derivatives increased by 26% in UV-treated plants relative to controls. The ratio of quercetin to kaempferol derivatives increased from 0.11 in controls to 0.91 in leaves of UV-treated plants. The leaf epidermis protected the inner leaf tissue where most of the photosynthetic apparatus is located. P. vulgaris was subjected to 6.17 kJ m-2 day-1 UV-BBE with different levels of visible light. The largest UV-induced changes in photosynthesis, chlorophyll, carotenoids, UV-screening pigments, and surface leaf reflectance occurred under growth conditions of low levels of visible light together with UV radiation

  5. Response of a SiC Photodiode to Extreme Ultraviolet through Visible Radiation

    International Nuclear Information System (INIS)

    The responsivity of a type 6H-SiC photodiode in the 1.5-400 nm wavelength range was measured using synchrotron radiation. The responsivity was 0.20 A/W at 270 nm and was less than 0.10 A/W in the extreme ultraviolet (EUV) region. The responsivity was calculated using a proven optical model that accounted for the reflection and absorption of the incident radiation and the variation of the charge collection efficiency (CCE) with depth into the device. The CCE was determined from the responsivity measured in the 200-400 nm wavelength range. By use of this CCE and the effective pair creation energy (7.2 eV) determined from x-ray absorption measurements, the EUV responsivity was accurately modeled with no free parameters. The measured visible-light sensitivity, although low compared with that of a silicon photodiode, was surprisingly high for this wide bandgap semiconductor

  6. Ultraviolet-B radiation enhancement in dielectric barrier discharge based xenon chloride exciplex source by air

    International Nuclear Information System (INIS)

    A single barrier dielectric barrier discharge tube of quartz with multi-strip Titanium-Gold (Ti-Au) coatings have been developed and utilized for ultraviolet-B (UV-B) radiation production peaking at wavelength 308 nm. The observed radiation at this wavelength has been examined for the mixtures of the Xenon together with chlorine and air admixtures. The gas mixture composition, chlorine gas content, total gas pressure, and air pressure dependency of the UV intensity, has been analyzed. It is found that the larger concentration of Cl2 deteriorates the performance of the developed source and around 2% Cl2 in this source produced optimum results. Furthermore, an addition of air in the xenon and chlorine working gas environment leads to achieve same intensity of UV-B light but at lower working gas pressure where significant amount of gas is air.

  7. The effects of ultraviolet-A radiation on visual evoked potentials in the young human eye

    International Nuclear Information System (INIS)

    A recent study from this laboratory using visual evoked potentials (VEPs) demonstrated that children's eyes are capable of detecting ultraviolet radiation. The aim of this study was to compare dose-response relationships in two age groups, 6-10 years (n=10) and 20-25 years (n=10). Under photopic viewing conditions (550 lux), exposures of monochromatic UV-A (339 nm) and visible radiation (502 nm) were correlated to VEPs. The results demonstrate that monochromatic UV-A can elicit age and dose dependent responses in the human visual system, suggesting that the eyes of children are more responsive to UV stimuli than the eyes of young adults. (au) 17 refs

  8. Ultraviolet B radiation was increased at ground level in scotland during a period of ozone depletion.

    Science.gov (United States)

    Moseley, H; Mackie, R M

    1997-07-01

    The potentially harmful effects associated with stratospheric ozone depletion are widely acknowledged. As the ozone layer principally absorbs ultraviolet (UV) radiation of wavelengths below 290 nm, reductions in stratospheric ozone levels are likely to result in increased UVB at the earth's surface, with the risk of increased incidence of skin cancer. Measuring the sun's spectrum at ground level requires sophisticated and reliable spectral instruments. Results are reported for this for the first time in the U.K. using spectral instruments, showing a significant increase in short wavelength UV radiation at a time of depleted stratospheric ozone. If this trend increases, future ozone depletion could contribute to known risks for cutaneous malignancies of all types. PMID:9274633

  9. [Human behavior in the solar radiation field with reference to ultraviolet exposure].

    Science.gov (United States)

    Schauberger, G; Keck, G; Cabaj, A

    1992-09-01

    There is a causal relation between solar ultraviolet radiation and skin cancer. For epidemiological investigations, quantification of the UV exposure is essential. To set up a risk assessment for the whole population, a representative survey was performed in Austria. The questionnaire refers to three sectors of everyday life: work, recreation and holidays; in addition the use of solaria is asked about for a further investigation. The UV exposure caused by humans' behaviour in the field of solar radiation was analysed from various demographic aspects. For some subpopulations the UV exposure sustained during work, recreation and holidays was compared. Groups with high occupational UV exposure show a weaker tendency to stay outdoors during leisure time and holidays than groups characterized by high UV exposure in their leisure time, who also prefer sun-intensive activities during holidays. PMID:1399598

  10. The effects of ultraviolet radiation on growth and bleaching in three species of Hawaiian coral

    Energy Technology Data Exchange (ETDEWEB)

    Goodman, G.D. (California State Univ., Long Beach (United States))

    1990-01-09

    Long term exposure to ultraviolet radiation is harmful to many organisms, including hermatypic corals, which obtain much of their nutrition from photosynthetic zooxanthellae. Therefore, increased UV radiation from atmospheric ozone depletion could inhibit growth of such corals. Moreover, coral bleaching, which has been attributed to loss of pigment and/or expulsion of zooxanthellae, may be a specific response to UV light. Does UV-A reduce skeletal growth or influence population density and pigment content of zooxanthellae In addition, do zooxanthellae migrate to shaded areas of the colony to avoid ultraviolet light Using alizarin red stain and suitable filters, I compared the stain and suitable filters, I compared the effects of UV-A (320-400nm) and full-spectrum UV (280-400nm) on the skeletal growth of two Hawaiian corals, Montipora verrucosa, Pocillopora damicornis, in situ. In the perforate corals, M. Verrucosa and Porites compressa, I measured concentration of zooxanthellae and their chlorophyll content to quantify bleaching in response to UV light. Reduction in skeletal growth by the two corals in response to different ranges of UV light appears to be species specific. Bleaching by UV appears to be characterized by an initial loss of pigment followed by the expulsion and migration of the zooxanthellae to shaded areas of the colony. Differences in tolerance and adaptation to decreasing ozone levels and increasing UV light should confer a competitive advantage on various species and morphologies of reef-building corals.

  11. Synchrotron Vacuum Ultraviolet Light and Soft X-Ray Radiation Effects on Aluminized Teflon FEP Investigated

    Science.gov (United States)

    Dever, Joyce A.; Townsend, Jacqueline A.; Gaier, James R.; Jalics, Alice I.

    1999-01-01

    Since the Hubble Space Telescope (HST) was deployed in low Earth orbit in April 1990, two servicing missions have been conducted to upgrade its scientific capabilities. Minor cracking of second-surface metalized Teflon FEP (DuPont; fluorinated ethylene propylene) surfaces from multilayer insulation (MLI) was first observed upon close examination of samples with high solar exposure retrieved during the first servicing mission, which was conducted 3.6 years after deployment. During the second HST servicing mission, 6.8 years after deployment, astronaut observations and photographic documentation revealed significant cracks in the Teflon FEP layer of the MLI on both the solar- and anti-solar-facing surfaces of the telescope. NASA Goddard Space Flight Center directed the efforts of the Hubble Space Telescope MLI Failure Review Board, whose goals included identifying the low-Earth-orbit environmental constituent(s) responsible for the cracking and embrittling of Teflon FEP which was observed during the second servicing mission. The NASA Lewis Research Center provided significant support to this effort. Because soft x-ray radiation from solar flares had been considered as a possible cause for the degradation of the mechanical properties of Teflon FEP (ref. 1), the effects of soft xray radiation and vacuum ultraviolet light on Teflon FEP were investigated. In this Lewisled effort, samples of Teflon FEP with a 100-nm layer of vapor-deposited aluminum (VDA) on the backside were exposed to synchrotron radiation of various vacuum ultraviolet and soft x-ray wavelengths between 18 nm (69 eV) and 0.65 nm (1900 eV). Synchrotron radiation exposures were conducted using the National Synchrotron Light Source at Brookhaven National Laboratory. Samples of FEP/VDA were exposed with the FEP surface facing the synchrotron beam. Doses and fluences were compared with those estimated for the 20-yr Hubble Space Telescope mission.

  12. Effects of ultraviolet-B radiation on fungal disease development in Cucumis sativus

    Energy Technology Data Exchange (ETDEWEB)

    Orth, A.B.; Teramura, A.H.; Sisler, H.D. (Univ. of Maryland, College Park (USA))

    1990-09-01

    Stratospheric ozone depletion due to increased atmospheric pollutants has received considerable attention because of the potential increase in ultraviolet-B (UV-B, 280-320 nm) radiation that will reach the earth's surface. Three cucumber (Cucumis sativus L.) cultivars were exposed to a daily dose of 11.6 kJ m{sup {minus}2} biologically effective ultraviolet-B (UV-B{sub BE}) radiation in an unshaded greenhouse before and/or after injection by Colletotrichum lagenarium (Pass.) Ell. and Halst. or Cladosporium cucumerinum Ell. and Arth. and analyzed for disease development. Two of these cultivars, Poinsette and Calypso Hybrid, were disease resistant, while the third cultivar, Straight-8, was disease susceptible. Preinfectional treatment of 1 to 7 days with UV-B{sub BE} in Straight-8 led to greater severity of both diseases. Postinfectional UV treatment did not lead to increased disease severity caused by C. lagenarium, while preinfectional UV treatment in both Straight-8 and Poinsette substantially increased disease severity. Although resistant cultivars Poinsette and Calypso Hybrid showed increased anthracnose disease severity when exposed to UV-B, this effect was apparent only on the cotyledons. Both higher spore concentration and exposure to UV-B radiation resulted in greater disease severity. Of the cucumber cultivars tested for UV-B sensitivity, growth in Poinsette was most sensitive and Calypso Hybrid was least sensitive. These preliminary results indicate that the effects of UV-B radiation on disease development in cucumber vary depending on cultivar, timing and duration of UV-B exposure, inoculation level, and plant age.

  13. Bioprocess of Kosa bioaerosols: effect of ultraviolet radiation on airborne bacteria within Kosa (Asian dust).

    Science.gov (United States)

    Kobayashi, Fumihisa; Maki, Teruya; Kakikawa, Makiko; Yamada, Maromu; Puspitasari, Findya; Iwasaka, Yasunobu

    2015-05-01

    Kosa (Asian dust) is a well-known weather phenomenon in which aerosols are carried by the westerly winds from inland China to East Asia. Recently, the frequency of this phenomenon and the extent of damage caused have been increasing. The airborne bacteria within Kosa are called Kosa bioaerosols. Kosa bioaerosols have affected ecosystems, human health and agricultural productivity in downwind areas. In order to develop a new and useful bacterial source and to identify the source region of Kosa bioaerosols, sampling, isolation, identification, measurement of ultraviolet (UV) radiation tolerance and experimental simulation of UV radiation conditions were performed during Kosa bioaerosol transportation. We sampled these bioaerosols using a Cessna 404 airplane and a bioaerosol sampler at an altitude of approximately 2900 m over the Noto Peninsula on March 27, 2010. The bioaerosol particles were isolated and identified as Bacillus sp. BASZHR 1001. The results of the UV irradiation experiment showed that the UV radiation tolerance of Kosa bioaerosol bacteria was very high compared with that of a soil bacterium. Moreover, the UV radiation tolerance of Kosa bioaerosol spores was higher than that of soil bacterial spores. This suggested that Kosa bioaerosols are transported across the atmosphere as living spores. Similarly, by the experimental simulation of UV radiation conditions, the limited source region of this Kosa bioaerosol was found to be southern Russia and there was a possibility of transport from the Kosa source area. PMID:25735592

  14. Competitive interaction in plant populations exposed to supplementary ultraviolet-B radiation

    International Nuclear Information System (INIS)

    Changes in plant growth and competitive balance between pairs of competing species were documented as a result of supplementary ultraviolet-B radiation (principally in the 290-315 nm waveband) under field conditions. This component of the terrestrial solar spectrum would be intensified if the atmospheric ozone layer were reduced. A method for calculating and statistically analyzing relative crowding coefficients was developed and used to evaluate the competitive status of the species pairs sown in a modified replacement series. The effect of the supplementary UV-B irradiance was generally detrimental to plant growth, and was reflected in decreased leaf area, biomass, height and density as well as changes competitive balance for various species. For some species, interspecific competition apparently accentuated the effect of the UV-B radiation, while more intense intraspecific competition may have had the same effect for other species. A few species when grown in a situation of more severe mutual interspecific competition exhibited enhanced growth under the UV-B radiation treatment. This, however, was usually associated with a detrimental effect of the radiation, on its competitor and thus was likely the result of its improved competitive circumstance rather than a benefical physiological effect of the radiation. (orig.)

  15. Ultraviolet-B radiation effects on phenolic profile and flavonoid content of Kalanchoe pinnata.

    Science.gov (United States)

    Nascimento, Luana Beatriz dos Santos; Leal-Costa, Marcos Vinicius; Menezes, Eloá Aragão; Lopes, Virgínia Rodrigues; Muzitano, Michelle Frazão; Costa, Sônia Soares; Tavares, Eliana Schwartz

    2015-07-01

    Ultraviolet-B radiation is an important abiotic factor that can stimulate the production of secondary metabolites, including polyphenolic compounds. Kalanchoe pinnata (Crassulaceae) is a medicinal plant popularly used in Brazil for treating wounds and inflammation. This species is rich in phenolic compounds, which could account for some of its biological activities, including antileishmanial, antihypertensive and antibacterial properties. We investigated the effects of supplemental UV-B radiation on the phenolic profile, antioxidant activity and total flavonoid content of leaves of K. pinnata. Plants were grown under white light (W - control) and supplemental UV-B radiation (W+UVB). Supplemental UV-B radiation enhanced the total flavonoid content of the leaf extracts, without affecting the antioxidant activity or yield of extracts. Analysis by TLC and HPLC of W and W+UVB leaf extracts revealed quantitative and qualitative differences in their phenolic profiles. W+UVB extracts contained a higher diversity of phenolic compounds and a larger amount of quercitrin, an important bioactive flavonoid of this species. This is the first report of the use of ImageJ® program to analyze a TLC visualized by spraying with NP-PEG reagent. UV-B radiation is proposed as a supplemental light source in K. pinnata cultivation in order to improve its flavonoid composition. PMID:25900552

  16. Autocorrelation in ultraviolet radiation measured at ground level using detrended fluctuation analysis

    Science.gov (United States)

    da Silva Filho, Paulo Cavalcante; da Silva, Francisco Raimundo; Corso, Gilberto

    2016-07-01

    In this study, we analyzed the autocorrelation among four ultraviolet (UV) radiation data sets obtained at 305 nm, 320 nm, 340 nm, and 380 nm. The data were recorded at ground level at the INPE climate station in Natal, RN, Brazil, which is a site close to the equator. The autocorrelations were computed by detrended fluctuation analysis (DFA) to estimate the index α. We found that the ​fluctuations in the UV radiation data were fractal, with scale-free behavior at a DFA index α ≃ 0.7. In addition, we performed a power law spectral analysis, which showed that the power spectrum exhibited a power law behavior with an exponent of β ≃ 0.45. Given that the theoretical result is β = 2 α - 1, these two results are in good agreement. Moreover, the application of the DFA ​method to the UV radiation data required detrending using a polynomial with an order of at least eight, which was related to the complex daily solar radiation curve obtained at ground level in a tropical region. The results indicated that the α exponent of UV radiation is similar to other climatic records such as air temperature, wind, or rain, but not solar activity.

  17. The effects of ultraviolet-B radiation on freshwater invertebrates: Experiments with a solar simulator

    Science.gov (United States)

    Hurtubise, R.D.; Havel, J.E.; Little, E.E.

    1998-01-01

    There is concern that decreases in stratospheric ozone will lead to hazardous levels of ultraviolet-B (UV-B) radiation at the Earth's surface. In clear water, UV-B may penetrate to significant depths. The purpose of the current study was to compare the sensitivity of freshwater invertebrates to UV-B. We used a solar simulator, calibrated to match local ambient solar radiation, to expose five species of freshwater invertebrates to enhanced levels of UV-B radiation. UV-B measurements in a eutrophic pond revealed that 10% of the irradiance penetrated to 30-cm depth and 1% to 57-cm depth. The irradiance at the upper 5-20 cm was comparable to levels used in the simulator. Median lethal dose (LD50) values were determined for the cladocerans Ceriodaphnia reticulata, Scapholeberis kingii (two induced color morphs), and Daphnia magna; the ostracod Cyprinotus incongruens; and the amphipod Hyalella azteca. Among the species, 96-h LD50 estimates were quite variable, ranging from 4.2 to 84.0 ??W cm-2. These estimates indicated S. kingii to be highly sensitive and H. azteca, C. reticulata, and D. magna to be moderately sensitive, whereas the ostracod C. incongruens was very tolerant to UV-B radiation. Overall, this study suggests that, in shallow ponds without physical refuges, UV-B radiation would have the strongest effects upon cladocerans and amphipods occurring in the water column, whereas ostracods would be better protected.

  18. Episode of unusual high solar ultraviolet radiation over central Europe due to dynamical reduced total ozone in May 2005

    OpenAIRE

    2006-01-01

    In late May 2005 unusual high levels of solar ultraviolet radiation were observed over central Europe. In Northern Germany the measured irradiance of erythemally effective radiation exceeded the climatological mean by more than about 20%. An extreme low ozone event for the season coincided with high solar elevation angles and high pressure induced clear sky conditions leading to the highest value of erythemal UV-radiation ever observed over this location in May since 1994. This hereafter call...

  19. Long-term variations of ultraviolet radiation in China from measurements and model reconstructions

    International Nuclear Information System (INIS)

    Measurements of ultraviolet (UV) radiation at 38 stations from Chinese Ecosystem Research Network during 2006–2012 were used for reconstructing the historical UV levels in China for the first time. UV models were introduced by analyzing the dependence of UV irradiation on clearness index (Kt) and cosine of solar zenith angle under any sky conditions in each station. Mean bias error (MBE), mean-absolute bias error (MABE) and root-mean-square error (RMSE) were used for assessing the model performance; relative differences between UV estimates and measurements were generally lower than 10% at most stations, which indicated that our all-sky UV models can produce acceptable estimates in China. Long-term UV values during 1961–2012 were then reconstructed for investigating the spatiotemporal characteristics of UV radiation in China based on daily global solar radiation (G) at 115 meteorological stations from China Meteorological Administration. Annual mean daily UV radiation ranged from 0.55 MJ m−2 d−1 to 0.65 MJ m−2 d−1 with average value being about 0.61 MJ m−2 d−1. It was also discovered that UV radiation decreased slightly at about −2.72 kJ m−2 d−1 per decade during the study period and there was an increasing trend since 1991 (0.7 kJ m−2 d−1 per year). - Highlights: • UV radiation at 38 stations was used for model development in China. • All-sky UV models produce satisfied estimates at hourly/daily basis. • UV levels during 1961–2012 were reconstructed for the first time in China. • Spatiotemporal variability of UV radiation in China was investigated

  20. Cancer risk at low doses of ionizing radiation: artificial neural networks inference from atomic bomb survivors

    OpenAIRE

    Sasaki, Masao S.; Tachibana, Akira; Takeda, Shunichi

    2013-01-01

    Cancer risk at low doses of ionizing radiation remains poorly defined because of ambiguity in the quantitative link to doses below 0.2 Sv in atomic bomb survivors in Hiroshima and Nagasaki arising from limitations in the statistical power and information available on overall radiation dose. To deal with these difficulties, a novel nonparametric statistics based on the ‘integrate-and-fire’ algorithm of artificial neural networks was developed and tested in cancer databases established by the R...

  1. Cancer risk at low doses of ionizing radiation: artificial neural networks inference from atomic bomb survivors.

    OpenAIRE

    Sasaki, Masao S.; Tachibana, Akira; Takeda, Shunichi

    2014-01-01

    Cancer risk at low doses of ionizing radiation remains poorly defined because of ambiguity in the quantitative link to doses below 0.2 Sv in atomic bomb survivors in Hiroshima and Nagasaki arising from limitations in the statistical power and information available on overall radiation dose. To deal with these difficulties, a novel nonparametric statistics based on the 'integrate-and-fire' algorithm of artificial neural networks was developed and tested in cancer databases established by the R...

  2. Prediction of Global Solar Radiation in India using Artificial Neural Network

    OpenAIRE

    Rajiv Gupta; Saurabh Singhal

    2016-01-01

    Increasing global warming and decreasing fossil fuel reserves has necessitated the use of renewable energy resources like solar energy in India. To maximize return on a solar farm, it had to be set up at a place with high solar radiation. The solar radiation values are available only for a small number of places and must be interpolated for the rest. This paper utilizes Artificial Neural Network in interpolation, by obtaining a function with input as combinations of 7 geographical and meteoro...

  3. The effect of solar ultraviolet radiation (UVR on induction of skin cancers

    Directory of Open Access Journals (Sweden)

    Marta Pacholczyk

    2016-04-01

    Full Text Available Ultraviolet radiation is a physical mutagenic and cancerogenic factor. About 95% of ultraviolet A (UVA (320–400 nm and 5% of UVB (280–320 nm reach the Earth’s surface. Melanin is a natural skin protective factor against UV radiation. Skin cancers associated with long-term exposure to UV radiation are: basal cell carcinoma (BCC, squamous cell carcinoma (SCC and cutaneous malignant melanoma (CMM. The high risk of BCC development is related to acute and repeated exposure to UV causing sunburn. Molecular studies of BBC demonstrated disorders in sonic hedgehog (SHH cell signaling regulation pathway, associated with the suppressor protein patched homolog 1 gene (PTCH1 mutations. The risk of the BCC development is related to the polymorphism of melanokortin-1 receptor gene (MC1R. Tumor P53 gene mutations observed in BCC cells has been classified as secondary genetic changes. In SCC cells UV-induced mutations were mostly related to P53 gene. Increased expression of cyclooxigenase- 2 gene (COX-2 plays a significant role in the development of SCC. Other pathogenetic factors include intensification of the synthesis of pro-inflammatory cytokines (tumor necrosis factor α (TNF-α, interleukin-1 α (IL-1α, IL-1β and IL-6. Currently, the role of UVB has been recognized in the pathogenesis of CMM. In CMM cells the following gene mutations were noted: cyclindependent kinase inhibitor 2A INK4A (p16INK4A, cyclin-dependent kinase 4 (CDK4, Ras, phosphatase and tensin homolog deleted on chromosome 10 (PTEN and proto-oncogene B-Raf (BRAF. The BRAF gene mutations were observed in ~50% of CMM cases. Mutations of P53 gene are not characteristic of CMM cells. Med Pr 2016;67(2:255–266

  4. Effects of Ozone and Cloud Cover on Surface Ultraviolet Radiation at High Southern Latitudes

    Science.gov (United States)

    Liao, Y.; Frederick, J. E.

    2002-12-01

    For over twenty years, the high latitude ozone depletion during austral springs and the increased surface ultraviolet (UV) radiation have caused concern due to the potential for negative biological and ecological effects. Since little long-term information on surface UV is available, the capability of assessing these effects has been limited. For a better understanding of the UV environment during springtime in the polar region, the National Science Foundation (NSF) Ultraviolet (UV) Monitoring Network was established in 1987 by the NSF Office of Polar Programs. Four out of the six sites, Ushuaia, Argentina (54°49'S, 68°19'W), Palmer Station, Antarctica (64°46'S, 64°03'W), McMurdo Station, Antarctica (77°51'S, 166°40'E), and South Pole Station, Antarctica (90°S), were at high southern latitudes. With the data at these four sites for over a decade (1990-2001), we were able to study the behavior of surface UV radiation in the south polar region, including the attenuation provided by total column ozone and cloud cover. To specify the effect of ozone on surface UV radiation, we used effective clear sky irradiances that were estimated from the actual measurements in a reference wavelength band from 342.5 to 347.5 nm throughout all years covered by the data. The effects of cloud cover can be obtained by taking ratios of measured UV irradiances to the corresponding effective clear sky values. We anticipate an upward trend in the surface UV irradiance in response to changes in total column ozone alone over the decadal time scale, and occasional abnormally large and small values due to the combined effects of variability in ozone and cloud cover. The latter case can be demonstrated by the fact that the monthly-integrated irradiance of UVB2 measured for October 1991 is actually 99.2% larger than the smallest value that was observed in October 1990.

  5. [The effect of solar ultraviolet radiation (UVR) on induction of skin cancers].

    Science.gov (United States)

    Pacholczyk, Marta; Czernicki, Jan; Ferenc, Tomasz

    2016-01-01

    Ultraviolet radiation is a physical mutagenic and cancerogenic factor. About 95% of ultraviolet A (UVA) (320-400 nm) and 5% of UVB (280-320 nm) reach the Earth's surface. Melanin is a natural skin protective factor against UV radiation. Skin cancers associated with long-term exposure to UV radiation are: basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and cutaneous malignant melanoma (CMM). The high risk of BCC development is related to acute and repeated exposure to UV causing sunburn. Molecular studies of BBC demonstrated disorders in sonic hedgehog (SHH) cell signaling regulation pathway, associated with the suppressor protein patched homolog 1 gene (PTCH1) mutations. The risk of the BCC development is related to the polymorphism of melanokortin-1 receptor gene (MC1R). Tumor P53 gene mutations observed in BCC cells has been classified as secondary genetic changes. In SCC cells UV-induced mutations were mostly related to P53 gene. Increased expression of cyclooxigenase- 2 gene (COX-2) plays a significant role in the development of SCC. Other pathogenetic factors include intensification of the synthesis of pro-inflammatory cytokines (tumor necrosis factor α (TNF-α), interleukin-1 α (IL-1α), IL-1β and IL-6). Currently, the role of UVB has been recognized in the pathogenesis of CMM. In CMM cells the following gene mutations were noted: cyclindependent kinase inhibitor 2A INK4A (p16INK4A), cyclin-dependent kinase 4 (CDK4), Ras, phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and proto-oncogene B-Raf (BRAF). The BRAF gene mutations were observed in ~50% of CMM cases. Mutations of P53 gene are not characteristic of CMM cells. Med Pr 2016;67(2):255-266. PMID:27221301

  6. Soybean growth responses to enhanced levels of ultraviolet-B radiation under greenhouse conditions

    International Nuclear Information System (INIS)

    Soybean (Glycine max [L.] Merr. cv. Essex) was grown in an unshaded greenhouse under three levels of biologically effective ultraviolet-B (UV-BBE) radiation (effective daily dose: 0, 11.5 and 13.6 kJ m-2) for 91 days. Plants were harvested at regular intervals beginning 10 days after germination until reproductive maturity. Mathematical growth analysis revealed that the effects of UV-B radiation varied with plant growth stage. The transition period between vegetative and reproductive growth was the most sensitive to UV-B radiation. Intermediate levels of UV-B had deleterious effects on plant height, leaf area, and total plant dry weight at late vegetative and reproductive stages of development. Specific leaf weight increased during vegetative growth but was unaffected by UV-B during reproductive growth stages. Relative growth, net assimilation, and stem elongation rates were decreased by UV-B radiation during vegetative and early reproductive growth stages. Variation in plant responses may be due in part to changes in microclimate within the plant canopy or to differences in repair or protection mechanisms at differing developmental stages. (author)

  7. Nonlinear generation of extreme-ultraviolet radiation in atomic hydrogen using electromagnetically induced transparency

    International Nuclear Information System (INIS)

    Sum-frequency generation enhanced by electromagnetically induced transparency (EIT) has been extended to the production of extreme ultraviolet (XUV) radiation in the range 97.3 endash 92.6 nm from np-1s transitions (n=4 endash 8) in atomic hydrogen. Pulsed radiation was generated by strong coupling of the np and 2s levels with laser radiation at Balmer wavelengths, and simultaneously (weaker) coupling of the 2s and 1s levels by two-photon resonance with 243-nm laser radiation. Investigations were carried out over a range of laser intensities and products of interaction length and atomic density (NL). As the product NL increased, the XUV intensities were greatly enhanced by EIT, and at high NL values, the spectral distributions of some of the generated signals were found to be distorted by the presence of molecular hydrogen. Calculated profiles, modified to incorporate the effects of nearby molecular resonances, were shown to be in good agreement with the observed spectra. copyright 1997 The American Physical Society

  8. Synergistic effects of ultraviolet radiation, thermal cycling and atomic oxygen on altered and coated Kapton surfaces

    Science.gov (United States)

    Dever, Joyce A.; Bruckner, Eric J.; Rodriguez, Elvin

    1992-01-01

    The photovoltaic (PV) power system for Space Station Freedom (SSF) uses solar array blankets which provide structural support for the solar cells and house the electrical interconnections. In the low earth orbital (LEO) environment where SSF will be located, surfaces will be exposed to potentially damaging environmental conditions including solar ultraviolet (UV) radiation, thermal cycling, and atomic oxygen. It is necessary to use ground based tests to determine how these environmental conditions would affect the mass loss and optical properties of candidate SSF blanket materials. Silicone containing, silicone coated, and SiO(x) coated polyimide film materials were exposed to simulated LEO environmental conditions to determine their durability and whether the environmental conditions of UV, thermal cycling and oxygen atoms act synergistically on these materials. A candidate PV blanket material called AOR Kapton, a polysiloxane polyimide cast from a solution mixture, shows an improvement in durability to oxygen atoms erosion after exposure to UV radiation or thermal cycling combined with UV radiation. This may indicate that the environmental conditions react synergistically with this material, and the damage predicted by exposure to atomic oxygen alone is more severe than that which would occur in LEO where atomic oxygen, thermal cycling and UV radiation are present together.

  9. Phytochemicals as protectors against ultraviolet radiation: versatility of effects and mechanisms.

    Science.gov (United States)

    Dinkova-Kostova, Albena T

    2008-10-01

    Ultraviolet (UV) radiation is one of the most abundant carcinogens in our environment, and the development of non-melanoma skin cancers, the most common type of human malignancy worldwide, represents one of the major consequences of excessive exposure. Because of growing concerns that the level of UV radiation is increasing as a result of depletion of the stratospheric ozone and climate change, the development of strategies for protection of the skin is an urgent need. Many phytochemicals that belong to various families of secondary metabolites, such as alkaloids (caffeine, sanguinarine), flavonoids [(-)-epigallocatechin 3-gallate, genistein, silibinin], carotenoids ( beta-carotene, lycopene), and isothiocyanates (sulforaphane), offer exciting platforms for the development of such protective strategies. These phytochemicals have been consumed by humans for many centuries as part of plant-rich diets and are presumed to be of low toxicity, an essential requirement for a chemoprotective agent. Mechanistically, they affect multiple signalling pathways and protect against UV radiation-inflicted damage by their ability to act as direct and indirect antioxidants, as well as anti-inflammatory and immunomodulatory agents. Such "pluripotent character" is a critical prerequisite for an agent that is designed to counteract the multiple damaging effects of UV radiation. Especially attractive are inducers of the Keap1/Nrf2/ARE pathway, which controls the gene expression of proteins whose activation leads to enhanced protection against oxidants and electrophiles. Such protection is comprehensive, long-lasting, and unlikely to cause pro-oxidant effects or interfere with the synthesis of vitamin D. PMID:18696411

  10. Effects of ultraviolet B radiation on (not so transparent exopolymer particles

    Directory of Open Access Journals (Sweden)

    E. Ortega-Retuerta

    2009-07-01

    Full Text Available Transparent exopolymer particles (TEP are the most ubiquitous gel particles in the ocean and form abiotically from dissolved precursors. Although these particles can accumulate at the ocean surface, being thus exposed to intense sunlight, the role of solar radiation on the assembly and degradation of TEP is unknown. In this study, we experimentally determined the effects of visible and ultraviolet B (UVB radiation on (1 TEP degradation (photolysis experiments, (2 TEP assembly from dissolved polymers (photoinhibition experiments and (3 TEP release by microorganisms. Solar radiation, particularly in the UVB range, caused significant TEP photolysis, with loss rates from 27 to 34% per day. Dissolved polysaccharides did not increase in parallel. No TEP were formed under UVB, visible or dark conditions, indicating that light does not promote TEP assembly. UVB radiation enhanced TEP release by microorganisms, possibly due to cell deaths, or as a protective measure. Increases in UVB may lead to enhanced TEP photolysis in the ocean, with further consequences for TEP dynamics and, ultimately, sea-air gas exchange.

  11. Radiation of lamp and optimized experiment using artificial light in the Arctic Ocean

    Institute of Scientific and Technical Information of China (English)

    ZHAO Jin-ping; David Barber; LI Tao; LI Shu-jiang; LI Xiang

    2008-01-01

    A winter optical experiment by an artificial lamp was conducted in the Amundsen Bay of Arctic Ocean from November of 2007 to January of 2008. The radiation field emitted from an artificial lamp was measured and is introduced in this paper, and the optimized experiment project is discussed. It is demonstrated that the minimum size allowed of the lamp is determined by both the field of view (FOV) of optical instrument and the measuring distance from the lamp. Some problems that might influence on the experiment result often occur for a simple fluorescent lamp,such as instability, spatial nonuniformity, light divergence, effect of lamp temperature, etc. By the analysis of the light radiation, three kind of measures are proposed to control the quality of the experiment, i.e. keeping consistency of lamp size with FOV of instrument, calibrating in situ downwind, and conducting measurement in effective range. Among them, the downwind calibration is the key step to overcome most problems arose by the lamp. The experiment indicated that the reliable results can be obtained only when the optical measurement is coordinated with the radiation field of artificial lamp. The measured radiation property of the lamp was used to advise the field experiment to minimize measuring error. As the experiment by artificial lamp was the first attempt in the Arctic Ocean, the experience given by this paper is a valuable reference to the correlative studies.

  12. Vacuum Ultraviolet Radiation and Atomic Oxygen Durability Evaluation of HST Bi-Stem Thermal Shield Materials

    Science.gov (United States)

    Dever, Joyce; deGroh, Kim K.

    2002-01-01

    Bellows-type thermal shields were used on the bi-stems of replacement solar arrays installed on the Hubble Space Telescope (HST) during the first HST servicing mission (SMI) in December 1993. These thermal shields helped reduce the problem of thermal gradient- induced jitter observed with the original HST solar arrays during orbital thermal cycling and have been in use on HST for eight years. This paper describes ground testing of the candidate solar array bi-stem thermal shield materials including backside aluminized Teflon(R)FEP (fluorinated ethylene propylene) with and without atomic oxygen (AO) and ultraviolet radiation protective surface coatings for durability to AO and combined AO and vacuum ultraviolet (VOV) radiation. NASA Glenn Research Center (GRC) conducted VUV and AO exposures of samples of candidate thermal shield materials at HST operational temperatures and pre- and post-exposure analyses as part of an overall program coordinated by NASA Goddard Space Flight Center (GSFC) to determine the on-orbit durability of these materials. Coating adhesion problems were observed for samples having the AO- and combined AO/UV-protective coatings. Coating lamination occurred with rapid thermal cycling testing which simulated orbital thermal cycling. This lack of adhesion caused production of coating flakes from the material that would have posed a serious risk to HST optics if the coated materials were used for the bi-stem thermal shields. No serious degradation was observed for the uncoated aluminized Teflon(R) as evaluated by optical microscopy, although atomic force microscopy (AFM) microhardness testing revealed that an embrittled surface layer formed on the uncoated Teflon(R) surface due to vacuum ultraviolet radiation exposure. This embrittled layer was not completely removed by AO erosion, No cracks or particle flakes were produced for the embrittled uncoated material upon exposure to VUV and AO at operational temperatures to an equivalent exposure of

  13. The total amount of DNA damage determines ultraviolet-radiation-induced cytotoxicity after uniform or localized irradiation of human cells

    International Nuclear Information System (INIS)

    Full text: We have recently developed a micropore ultraviolet irradiation technique. An isopore membrane filter with 3 μm diameter pores shields ultraviolet C radiation from cultured human fibroblasts, leading to partial irradiation within the cells with an average of about three exposed areas per nucleus. This study addressed the question of whether the spatial distribution of DNA damage within a cell nucleus is important in triggering ultraviolet-induced cytotoxicity. We have examined whether there are differences in cytotoxicity between partially ultraviolet-irradiated cells and uniformly irradiated cells after equal amounts of DNA damage were induced in the cell nuclei. We first determined DNA damage formation in normal human fibroblasts using an enzyme-linked immunosorbent assay. We found that 5 J per m2 ultraviolet irradiation produced an equivalent amount of cyclobutane pyrimidine dimers and (6-4) photoproducts per cell as 100 J per m2 with the membrane filter shield. At those doses, we found that both types of ultraviolet irradiation induced similar levels of cytotoxicity as assessed by a 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4- sulfophenyl)-2H-tetrazolium assay. Both types of ultraviolet-irradiated cells also had similar cell-cycle distribution and apoptosis as measured by flow cytometry. Moreover, no significant differences in repair kinetics for either type of photolesion were observed between the two different ultraviolet treatments. Similar results were obtained in Cockayne syndrome cells that are defective in transcription-coupled nucleotide excision repair. Present results indicate that in the range of photoproducts studied, the spatial distribution of DNA damage within a cell is less important than the amount of damage in triggering ultraviolet-induced cytotoxicity

  14. The response of the early developmental stages of Laminaria japonica to enhanced ultraviolet-B radiation

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The responses of the early development of Laminaria japonica collected from Kiaochow Bay in China to enhanced ultraviolet-B radiation (UV-B, 280—320 nm) were studied in the laboratory. The low UV-B ra-diations (11.7—23.4 J·m-2·d-1) had no significant effects on zoospores attachment, but when the UV-B dose > 35.1 J·m-2·d-1 the attachment decreased significantly compared with the control. Germination of embryospores was >93% under the low (11.7—35.1 J·m-2·d-1) doses, and in the range of 78.5%—88.5% under the high (46.8—70.2 J·m-2·d-1) UV-B doses, indicating a significant radiation effect. Under the higher UV-B exposure (35.1—70.2 J·m-2·d-1), all of the few gametophytes formed from embryospores died 120 h post-release. After exposure to the low UV-B radiation (11.7—23.4 J·m-2·d-1), the formation of sporophytes decreased and the female gametophyte clones increased compared with the control. However, the sex ratio and the relative growth of female gametophytes/sporophytes had not signifi-cantly changed. According to the results, enhanced UV-B radiation has a significant effect on the early development of L. japonica under laboratory conditions, suggesting that the UV-B radiation could not be overlooked as one of the important environmental factors influencing the ontogeny of macroalgae living in marine ecosystems.

  15. The response of the early developmental stages of Laminaria japonica to enhanced ultraviolet-B radiation

    Institute of Scientific and Technical Information of China (English)

    LIU Su; ZHANG QuanSheng; WANG You; JU Qing; TANG XueXi

    2008-01-01

    The responses of the early development of Laminaria japonica collected from Kiaochow Bay in China to enhanced ultraviolet-B radiation (UV-B, 280-320 nm) were studied in the laboratory. The low UV-B radiations (11.7-23.4 J·m-2·d-) had no significant effects on zoospores attachment, but when the UV-B dose > 35.1 J·m-2·d-1 the attachment decreased significantly compared with the control. Germination of embryosperes was >93% under the low (11.7-35.1 J·m-2·d-1) doses, and in the range of 78.5%-88.5% under the high (46.8-70.2 J·m-2·d-1) UV-B doses, indicating a significant radiation effect. Under the higher UV-B exposure (35.1-70.2 J·m-2·d-1), all of the few gametophytes formed from embryospores died 120 h post-release. After exposure to the low UV-B radiation (11.7-23.4 J·m-2·d-1), the formation of sporophytes decreased and the female gametophyte clones increased compared with the control. However, the sex ratio and the relative growth of female gametophytes/sporophytes had not significantly changed. According to the results, enhanced UV-B radiation has a significant effect on the early development of L. japonica under laboratory conditions, suggesting that the UV-B radiation could not be overlooked as one of the important environmental factors influencing the ontogeny of macroalgae living in marine ecosystems.

  16. Measuring exposure to solar ultraviolet radiation using a dosimetric technique: understanding participant compliance issues.

    Science.gov (United States)

    Sun, Jiandong; Lucas, Robyn M; Harrison, Simone L; van der Mei, Ingrid; Whiteman, David C; Mason, Rebecca; Nowak, Madeleine; Brodie, Alison M; Kimlin, Michael G

    2014-01-01

    Personal ultraviolet dosimeters have been used in epidemiological studies to understand the risks and benefits of individuals' exposure to solar ultraviolet radiation (UVR). We investigated the types and determinants of noncompliance associated with a protocol for use of polysulphone UVR dosimeters. In the AusD Study, 1002 Australian adults (aged 18-75 years) were asked to wear a new dosimeter on their wrist each day for 10 consecutive days to quantify their daily exposure to solar UVR. Of the 10 020 dosimeters distributed, 296 (3%) were not returned or used (Type-I noncompliance) and other usage errors were reported for 763 (8%) returned dosimeters (Type-II noncompliance). Type-I errors were more common in participants with predominantly outdoor occupations. Type-II errors were reported more frequently on the first day of measurement; weekend days or rainy days; and among females; younger people; more educated participants or those with outdoor occupations. Half (50%) the participants reported a noncompliance error on at least 1 day during the 10-day period. However, 92% of participants had at least 7 days of usable data without any apparent noncompliance issues. The factors identified should be considered when designing future UVR dosimetry studies. PMID:24571445

  17. Ultraviolet radiation in skin ageing and carcinogenesis: the role of retinoids for treatment and prevention.

    Science.gov (United States)

    Oikarinen, A; Peltonen, J; Kallioinen, M

    1991-01-01

    The mechanisms of UV-induced ageing and carcinogenesis of the skin have been elucidated in animals and humans, and both UVB and UVA radiation have been shown to have deleterious effects on the skin. Thus the use of solaria which deliver mostly UVA radiation is not safe. There is also an increased risk of ageing when using therapeutic UV sources. UV radiation is beneficial in many cases of skin disorders such as psoriasis, atopic eczema, acne and pruritus. Nevertheless by careful patient selection and follow-up the risks of UV can be minimised when treating patients with artificial UV radiation. During recent years there has been intensive research into the development of agents which prevent harmful effects of radiation. The retinoids are particularly interesting as they enhance skin repair after UV damage, have an anticarcinogenic effect and are effective for treating precancerous lesions such as solar keratosis and as adjuvant therapy for skin cancers. Topical retinoids are already used for the treatment of actinic skin damage, and systemic retinoids are also used in certain groups of patients who have an increased risk of contracting skin cancers such as xeroderma pigmentosum. PMID:1756019

  18. Xeroderma pigmentosum neurological abnormalities correlate with colony-forming ability after ultraviolet radiation

    International Nuclear Information System (INIS)

    Xeroderma pigmentosum is an autosomal recessive disease in which DNA repair processes are defective. All xeroderma pigmentosum patients develop premature aging of sun exposed skin, and some develop neurological abnormalities due to premature death of nerve cells. Sensitivity to ultraviolet radiation of 24 xeroderma pigmentosum fibroblast strains was studied in vitro by measuring each strain's ability to divide and form colonies after irradiation. The most sensitive strains were derived from patients who had an early onset of neurological abnormalities; less sensitive strains were from patients with a later onset; and the most resistant strains were from patients without neurological abnormalities. The uv sensitivities of strains from each member of a sibling pair with xeroderma pigmentosum were identical, indicating that uv sensitivity of xeroderma pigmentosum strains is determined by the patient's inherited DNA repair defect. The results suggest that effective DNA repair is required to maintain the functional integrity of the human nervous system by preventing premature death of neurons

  19. The effects of ultraviolet radiation on the growth and gross morphology of Zea mays, Linn. seedlings

    International Nuclear Information System (INIS)

    The study was conducted with a descriptive experimental design in order to determine the effects of broad spectrum ultraviolet radiation on growth factors, seedling height, root length, chlorophyll content, organic weights, and percentage survival, as well as gross morphological factors, leaf, stem, and root appearance, of native sweet corn seedlings. The study was limited to the seedling stage of the plant and observations were taken after 20 days of treatment. The results gathered show that there was a visible manifestation of the detrimental effects of UV on the irradiated seedlings. There were observed decreases in the growth parameters while the gross morphological parameters exhibited signs of wilting and stress. It was therefore concluded that based on the observed results, UV had a detrimental effect on the studied growth and gross morphological parameters. (Author)

  20. Sensitivity of Escherichia coli acrA mutants to psoralen plus near-ultraviolet radiation

    International Nuclear Information System (INIS)

    The sensitivity to psoralen plus near-ultraviolet radiation (PUVA) was compared in a pair of E. coli strains differing at the acrA locus. Survival was determined for both bacteria and phage lambda. AcrA mutant cells were 40 times more sensitive than wild type to the lethal effect of PUVA. Free lambda phage exposed to PUVA survived as well when plated on acrA mutants as on wild type. In contrast, prophage lambda C1857 ind- carried in lysogenic acrA strains was hypersensitive to PUVA. The enhanced sensitivity of bacterial and lambda DNA, when inside acrA cells, was parallel by an increased photobinding of radiolabelled psoralens in the mutant. Binding was increased specifically to DNA rather than to nucleic acids in general. The difference in psoralen-binding ability determined by the acrA gene persisted after permeabilizing treatment of the cells. (orig./AJ)

  1. Leaf hairs of Olea europaea protect underlying tissues against ultraviolet-B radiation damage

    International Nuclear Information System (INIS)

    The photochemical efficiency of photosystem II, as measured by chlorophyll fluorescence induction, was not affected in de-haired olive leaves kept in the dark or intact leaves irradiated with a moderate (3.75 W m-2) ultraviolet-B (UV-B) intensity. In de-haired, UV-B-irradiated leaves, however, the ratio of variable to maximum (F(v)/F(m)) chlorophyll fluorescence declined significantly and irreversibly. Reduction in F(v)/V(m) was associated with an increase in instantaneous and a decrease in maximum (F(m)) fluorescence, indicating perturbation by the UV-B exposure of more than one photosynthetic site. Extensive epidermal browning in de-haired, UV-B irradiated leaves was also observed, indicating possible damage to cell membranes. The results strengthen the hypothesis that leaf hairs protect the underlying tissues against UV-B radiation damage

  2. The Effect of Exposure to Ultraviolet Radiation in Infancy on Melanoma Risk.

    Science.gov (United States)

    Gefeller, Olaf; Fiessler, Cornelia; Radespiel-Tröger, Martin; Uter, Wolfgang; Pfahlberg, Annette B

    2016-01-01

    Evidence on the effect of ultraviolet radiation (UVR) exposure in infancy on melanoma risk in later life is scarce. Three recent studies suffering from methodological shortcomings suggested that people born in spring carry a higher melanoma risk. Data from the Bavarian population-based cancer registry on 28374 incident melanoma cases between 2002 and 2012 were analyzed to reexamine this finding. Crude and adjusted analyses - using negative binomial regression models - were performed addressing the relationship. In the crude analysis, the birth months March - May were significantly overrepresented among melanoma cases. However, after additionally adjusting for the birth month distribution of the Bavarian population, the ostensible seasonal effect disappeared. Similar results emerged in all subgroup analyses. Our large registry-based study provides no evidence that people born in spring carry a higher risk for developing melanoma in later life and thus lends no support to the hypothesis of higher UVR-susceptibility during the first months of life. PMID:27577494

  3. Utilization of ultraviolet radiation in effluent disinfestation of domestic waste treatment systems

    International Nuclear Information System (INIS)

    Ultraviolet radiation disinfection of Upflow Anaerobic Sludge Biodigestor (UASB) and UASB with aerated lagoon pos-treatment effluents is possible to be reached utilizing a single low pressure mercury lamp arc (15 W nominal power) in a shell tube flow through reactor (1.2 L useful volume). Fecal coliforms, total coliforms and colifages were used as microbiological parameters. For fecal coliforms, about 3 logarithmic units (log. un.) was removed from UASB with aerated lagoon pos-treatment effluent and 4 log. un. from UASB effluent with 7 and 30 seconds of hydraulic retention time, respectively. Good empirical correlations were obtained between microbiological parameters and hydraulic retention times. (author). 4 refs, 1 fig, 3 tabs

  4. Sunscreen protection against ultraviolet radiation-induced pyrimidine dimers in mouse epidermal DNA

    International Nuclear Information System (INIS)

    Solar ultraviolet radiation (UVR) induces a number of pathologic conditions of mammalian skin including erythema, oedema, hyperplasia, sunburn cell formation and skin cancer. Consequently, UVR-induced DNA damage has been implicated as one of the photochemical events that results in the formation of these pathological changes. The ability of sunscreens to protect against UVR-induced DNA damage has not been well characterized especially with UVA (320-400 nm) wavelengths and UVA absorbers. In this paper we present results of a study aimed at determining the efficacy of two sunscreens at preventing the induction of pyrmidine dimers in basal cell DNA of mice exposed to solar-simulated UVR (SSUV) wavelengths (290-400 nm) or to UVA (320-400 nm). (author)

  5. Generation of Coherent Extreme-Ultraviolet Radiation Carrying Orbital Angular Momentum

    CERN Document Server

    Ribič, Primož Rebernik; De Ninno, Giovanni

    2013-01-01

    We propose an effective scheme for the generation of intense coherent extreme ultraviolet light beams carrying orbital angular momentum (OAM). The light is produced by a high-gain harmonic-generation free-electron laser (FEL), seeded using a laser pulse with a transverse staircase-like phase pattern. During amplification, diffraction and mode selection drive the radiation profile towards a dominant OAM mode at saturation. With a seed laser at 260 nm, gigawatt power levels are obtained at wavelengths approaching those of soft x-rays. Compared to other proposed schemes to generate OAM with FELs, our approach is robust, easier to implement, and can be integrated into already existing FEL facilities without extensive modifications of the machine layout.

  6. Some resistance mechanisms to ultraviolet radiation; Algunos mecanismos de resistencia a radiacion ultravioleta

    Energy Technology Data Exchange (ETDEWEB)

    Alcantara D, D. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2002-12-15

    The cyclical exposure of bacterial cells to the ultraviolet light (UV) it has as consequence an increment in the resistance to the lethal effects of this type of radiation, increment that happens as a result of a selection process of favorable genetic mutations induced by the same UV light. With object to study the reproducibility of the genetic changes and the associate mechanisms to the resistance to UV in the bacteria Escherichia coli, was irradiated cyclically with UV light five different derived cultures of a single clone, being obtained five stumps with different resistance grades. The genetic mapping Hfr revealed that so much the mutation events like of selection that took place during the adaptation to the UV irradiation, happened of random manner, that is to say, each one of the resistant stumps it is the result of the unspecified selection of mutations arisen at random in different genes related with the repair and duplication of the DNA. (Author)

  7. A novel sensor array for field based ocular ultraviolet radiation measurements

    International Nuclear Information System (INIS)

    The intensification of terrestrial solar ultraviolet radiation (UVR) due to the diminution of the ozone layer has promoted a variety of research into establishing the impact of this elevated potential dose of UVR on biological tissues. Certain anterior ocular tissues have been found to be susceptible to damage by incident UVR and potentially blinding diseases such as pterygium are thought to be a direct result of absorbed UVR at the nasal limbus. There is a need for more accurate quantification and localisation of incident UVR at the anterior ocular surface. A novel solar blind photodiode sensor array system has been designed, constructed and tested for this purpose. Initial measurements to quantify the irradiance across the anterior ocular surface within the latitudes known as the 'pterygium belt' provide us with a set of core data for different head orientations and tilt angles and indicate the accuracy and stability of the system. (authors)

  8. Symposium on diseases related to ultraviolet radiation: A risk-management approach

    International Nuclear Information System (INIS)

    A symposium on diseases related to ultraviolet radiation (UVR), sponsored by the Laboratory Centre for Disease Control was attended by 50 national and international experts in the fields of dermatology, ophthalmology and epidemiology, as well as representatives from various national and provincial public health organizations. The objectives of the symposium were as follows: to review the evidence relating UVR to the incidence of melanoma of the skin and eye, non melanotic cancer of the skin and lip, nonmalignant skin conditions and cataract; to review the effectiveness of primary prevention and early detection of UVR-related diseases; and to recommend strategies for risk management through regulation, public education and screening programs, as well as research priorities. Fourteen experts presented papers on issues related to UVR exposure. After the presentations the participants met in working groups to discuss questions pertaining to the identification, assessment and management of health risks relating to UVR. (author)

  9. Invisible marking system by extreme ultraviolet radiation: the new frontier for anti-counterfeiting tags

    Science.gov (United States)

    Di Lazzaro, P.; Bollanti, S.; Flora, F.; Mezi, L.; Murra, D.; Torre, A.; Bonfigli, F.; Montereali, R. M.; Vincenti, M. A.

    2016-07-01

    We present a marking technology which uses extreme ultraviolet radiation to write invisible patterns on tags based on alkali fluoride thin films. The shape of the pattern is pre-determined by a mask (in the case of contact lithography) or by a suitable mirror (projection lithography). Tags marked using this method offer a much better protection against fakes than currently available anti-counterfeiting techniques. The complexity and cost of this technology can be tailored to the value of the good to be protected, leaving, on the other hand, the specific reading technique straightforward. So far, we have exploited our invisible marking to tag artworks, identity cards, electrical components, and containers of radioactive wastes. Advantages and limits of this technology are discussed in comparison with the anti-counterfeiting systems available in the market.

  10. Operation shadow warrior: a quantitative analysis of the ultraviolet radiation protection demonstrated by various headgear.

    Science.gov (United States)

    Schissel, D J

    2001-09-01

    In the last 10 years, the scientific community and the media have highlighted the depletion of atmospheric ozone and the subsequent increase in ultraviolet radiation (UVR) that penetrates to the earth's surface. This UVR is associated with problems such as sunburn, photoaging, cataracts, and skin cancer. In the United States, skin cancer is among the top three reported cancers, and its incidence is increasing rapidly. Physicians agree that human exposure to UVR should be controlled by protecting the skin or limiting its exposure to UVR. As military physicians, our mission is to protect the fighting force and educate the command on the best possible course of action to accomplish this mission. In this paper, I quantitatively demonstrate that wearing the inventoried sun, woodland, type III cover is a far superior course of action when a commander desires a UVR counter measure for the fighting force. PMID:11569441

  11. Long-wave ultraviolet radiation induces protein kinase C in normal human keratinocytes

    International Nuclear Information System (INIS)

    Skin tumor promotion by phorbol ester is believed to be mediated by the phospholipid-dependent ser/thr kinase, protein kinase C (PKC). Long-wave ultraviolet radiation (320-400 nm, UVA), which has also been shown to promote skin tumors, induces elevated levels of PKC in murine fibroblasts, suggesting that UVA may promote the development of basal and squamous cell skin cancers by a mechanism involving PKC. To examine UVA effects on PKC in a model relevant to skin, we maintained normal human epidermal keratinocytes (NHEK) in serum-free medium and exposed the cultured cells to various doses of UVA or to the phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA). The findings suggest that acute UVA exposure elevates PKC activity in human keratinocytes and may act through PKC to promote actinic skin cancer. The molecular mechanism is likely to differ from that of the phorbol esters, however. (author)

  12. Solar ultraviolet radiation in Syria measurements and relationship with skin cancer incidence

    International Nuclear Information System (INIS)

    Seasonal variations of solar UVB (285-320) and UVA (320-400) were measured in three sites in Syria (33-37 N sup O) for two years: 1992-1993. UVB measurements were performed using polysulphone films and Robertson-Berger meter, while UVA measurements were done by NVA intensity meter. Two sets of measurements were carried out : - Maximal daily doses three times a week (every other day) - Diurnal variations from sun-rise to sun-set every two hours twice a month (every fortnight). The biological consequences of ultraviolet radiation withreference to some epidemiological data of skin cancer incidence in Syria since 1980 were discussed .(author). 36 refs., 21 figs., 11 tabs

  13. Ultraviolet radiation and sugar-induced chlorosis in detached leaves of Elodea densa

    International Nuclear Information System (INIS)

    When portions of the leaves of Elodea densa were exposed to shortwave ultraviolet (uv) radiation for 20 to 30 s at 2,000 μW/cm2, the chloroplasts of the irradiated tissue did not change in volume and remained green, but chloroplasts of the adjacent nonirradiated tissue decreased in volume, became yellow, and were transformed into yellow-orange chromoplasts during a 5 to 7-day period. Similar changes can be induced in nonirradiated leaves by incubating them in glucose or sucrose solutions. Chloroplasts in uv-exposed leaf tissue, however, remained green and did not decrease in volume even when incubated in glucose or sucrose solutions. Cycloheximide (10 ppM) prevented uv-induced yellowing of adjacent nonirradiated leaf tissue as well as glucose- and sucrose-induced yellowing in nonirradiated leaves. Similarly, cycloheximide prevented sugar-induced anthocyanin synthesis in the light. Cytoplasmic streaming continued in all treatments

  14. Short and long term variation in ultraviolet radiation and multiple sclerosis

    DEFF Research Database (Denmark)

    Menni, Cristina; Lowell, Walter E; Bentzen, Joan;

    2012-01-01

    We examined the role of ultraviolet radiation (UVR) in persons diagnosed with multiple sclerosis (MS) in four different populations, Italians, Danish, White and African Americans. We tested whether variation in UVR as determined by seasons (short term variation) and solar cycles (long term...... study the pattern of month of birth distribution in patients with MS comparing with general population data. T-tests were employed to study solar cycles association with lifespan. A surplus of births was observed in June for White Americans. A decrease of births in October and November, though not...... significant after multiple testing correction, was observed in the three populations. In White American with MS overall, males and females, we found that solar cycle is associated with lifespan. We found that season and solar cycles have some role in MS susceptibility and life duration. However, this is an...

  15. Reducing ultraviolet radiation exposure among outdoor workers: State of the evidence and recommendations

    Directory of Open Access Journals (Sweden)

    Buller David B

    2007-08-01

    Full Text Available Abstract Objective Outdoor workers have high levels of exposure to ultraviolet radiation and the associated increased risk of skin cancer. This paper describes a review of: 1 descriptive data about outdoor workers' sun exposure and protection and related knowledge, attitudes, and policies and 2 evidence about the effectiveness of skin cancer prevention interventions in outdoor workplaces. Data sources Systematic evidence-based review. Data synthesis We found variable preventive practices, with men more likely to wear hats and protective clothing and women more likely to use sunscreen. Few data document education and prevention policies. Conclusion Reports of interventions to promote sun-safe practices and environments provide encouraging results, but yield insufficient evidence to recommend current strategies as effective. Additional efforts should focus on increasing sun protection policies and education programs in workplaces and evaluating whether they improve the health behavior of outdoor workers.

  16. Long-term solar UV radiation reconstructed by Artificial Neural Networks (ANN

    Directory of Open Access Journals (Sweden)

    U. Feister

    2008-01-01

    Full Text Available Artificial Neural Networks (ANN are efficient tools to derive solar UV radiation from measured meteorological parameters such as global radiation, aerosol optical depths and atmospheric column ozone. The ANN model has been tested with different combinations of data from the two sites Potsdam and Lindenberg, and used to reconstruct solar UV radiation at eight European sites by more than 100 years into the past. Annual totals of UV radiation derived from reconstructed daily UV values reflect interannual variations and long-term patterns that are compatible with variabilities and changes of measured input data, in particular global dimming by about 1980–1990, subsequent global brightening, volcanic eruption effects such as that of Mt. Pinatubo, and the long-term ozone decline since the 1970s. Patterns of annual erythemal UV radiation are very similar at sites located at latitudes close to each other, but different patterns occur between UV radiation at sites in different latitude regions.

  17. The Role of Ultraviolet Radiation in the Ocular System of  Mammals

    Directory of Open Access Journals (Sweden)

    Mercede Majdi

    2014-10-01

    Full Text Available With decreasing levels of ozone in the atmosphere, we are being exposed to higher levels of ultraviolet radiation (UVR than ever before. UVR carries higher energy than visible light, and its effects on tissues include DNA damage, gene mutations, immunosuppression, oxidative stress and inflammatory responses. In the eye, UVR is strongly associated with the development of basal and squamous cell carcinoma of the eyelid, pterygium, photokeratitis, climatic droplet keratopathy, ocular surface squamous neoplasia, cataracts, and uveal melanoma, and is weakly associated with age-related macular degeneration. Despite overwhelming evidence regarding the deleterious effects on UVR, public health measures to encourage UV protection of the eyes is generally lacking. Options for photoprotection include sunglasses, wide brim hats, windshields, plastic films for side windows in cars, UV blocking contact lenses, and following the UV Index report daily. The American National Standards Institute currently has regulations regarding properties of UV blocking sunglasses; however, compliance in the US is not mandatory. On the other hand, UVR does have therapeutic applications in the eye, particularly, riboflavin activated by ultraviolet A light (UVA radiation is used clinically to slow the progression of keratoconus, post-LASIK keratectasia, and bullous keratopathy by crosslinking corneal collagen fibers. Additionally, riboflavin activated by UVA has been shown to have antibacterial, antiviral, and antiparasitic effects. This is clinically relevant in the treatment of infectious keratitis. Finally, exposure to low levels of light in the UV spectrum has been found to regulate the growth of the eye and lack of adequate exposure may increase the risk of development and progression of myopia.

  18. The Role of Macrophage Migration Inhibitory Factor (MIF) in Ultraviolet Radiation-Induced Carcinogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, Tadamichi [Department of Dermatology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Sugitani, 930-0194, Toyama (Japan)

    2010-08-09

    Ultraviolet (UV) radiation is the most common cause of physical injury to the skin due to environmental damage, and UV exposure substantially increases the risk of actinic damage to the skin. The inflammatory changes induced by acute UV exposure include erythema (sunburn) of the skin, while chronic exposure to solar UV radiation causes photo-aging, immunosuppression, and ultimately, carcinogenesis of the skin. After skin damage by UV radiation, the cells are known to secrete many cytokines, including interleukin (IL)-1, IL-6, tumor necrosis factor (TNF)-α. and macrophage migration inhibitory factor (MIF). MIF was originally identified as a lymphokine that concentrates macrophages at inflammatory loci, and is known to be a potent activator of macrophages in vivo. MIF is considered to play an important role in cell-mediated immunity. Since the molecular cloning of MIF cDNA, MIF has been re-evaluated as a proinflammatory cytokine and pituitary-derived hormone that potentiates endotoxemia. MIF is ubiquitously expressed in various tissues, including the skin. Recent studies have suggested a potentially broader role for MIF in growth regulation because of its ability to antagonize p53-mediated gene activation and apoptosis. This article reviews the latest findings on the roles of MIF with regard to UV-induced skin cancer.

  19. Decolorization of Methylene Blue by Ag/SrSnO3 Composites under Ultraviolet Radiation

    Directory of Open Access Journals (Sweden)

    Patcharanan Junploy

    2014-01-01

    Full Text Available SrSn(OH6 precursors synthesized by a cyclic microwave radiation (CMR process were calcined at 900°C for 3 h to form rod-like SrSnO3. Further, the rod-like SrSnO3 and AgNO3 in ethylene glycol (EG were ultrasonically vibrated to form rod-like Ag/SrSnO3 composites, characterized by X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, electron microscopy (EM, Fourier transform infrared (FTIR spectroscopy, and UV-visible analysis. The photocatalyses of rod-like SrSnO3, 1 wt%, 5 wt%, and 10 wt% Ag/SrSnO3 composites were studied for degradation of methylene blue (MB, C16H18N3SCl dye under ultraviolet (UV radiation. In this research, the 5 wt% Ag/SrSnO3 composites showed the highest activity, enhanced by the electron-hole separation process. The photoactivity became lower by the excessive Ag nanoparticles due to the negative effect caused by reduction in the absorption of UV radiation.

  20. Radiative transfer in a clumpy universe; 2, the ultraviolet extragalactic background

    CERN Document Server

    Haardt, F; Haardt, Francesco; Madau, Piero

    1995-01-01

    We present a detailed calculation of the propagation of AGN-like ionizing radiation through the intergalactic space. We model the ionization state of absorbing clouds, and show that the universe will be more opaque above 4\\,Ryd than previously estimated. Singly ionized helium in \\Lya forest clouds and Lyman-limit systems is found to be very efficient in reprocessing soft X-ray, helium-ionizing photons into ultraviolet, hydrogen-ionizing ones. We demonstrate that a significant fraction of the absorbed primary photons (emitted, e.g., by quasar sources) will be reradiated by the photoionized gas through \\Lya line emission, two-photon continuum, and recombination continuum radiation. In the light of new data and recent studies, we also reassess the contribution of the QSOs observed in optical surveys to the UV extragalactic background, and find that the stochastic reprocessing of quasar Lyman continuum radiation by hydrogen and helium along the line of sight will significantly affect the amplitude spectral shape,...

  1. Modeling of radiative properties of Sn plasmas for extreme-ultraviolet source

    Science.gov (United States)

    Sasaki, Akira; Sunahara, Atsushi; Furukawa, Hiroyuki; Nishihara, Katsunobu; Fujioka, Shinsuke; Nishikawa, Takeshi; Koike, Fumihiro; Ohashi, Hayato; Tanuma, Hajime

    2010-06-01

    Atomic processes in Sn plasmas are investigated for application to extreme-ultraviolet (EUV) light sources used in microlithography. We develop a full collisional radiative (CR) model of Sn plasmas based on calculated atomic data using Hebrew University Lawrence Livermore Atomic Code (HULLAC). Resonance and satellite lines from singly and multiply excited states of Sn ions, which contribute significantly to the EUV emission, are identified and included in the model through a systematic investigation of their effect on the emission spectra. The wavelengths of the 4d-4f+4p-4d transitions of Sn5+ to Sn13+ are investigated, because of their importance for determining the conversion efficiency of the EUV source, in conjunction with the effect of configuration interaction in the calculation of atomic structure. Calculated emission spectra are compared with those of charge exchange spectroscopy and of laser produced plasma EUV sources. The comparison is also carried out for the opacity of a radiatively heated Sn sample. A reasonable agreement is obtained between calculated and experimental EUV emission spectra observed under the typical condition of EUV sources with the ion density and ionization temperature of the plasma around 1018 cm-3 and 20 eV, respectively, by applying a wavelength correction to the resonance and satellite lines. Finally, the spectral emissivity and opacity of Sn plasmas are calculated as a function of electron temperature and ion density. The results are useful for radiation hydrodynamics simulations for the optimization of EUV sources.

  2. Modeling of radiative properties of Sn plasmas for extreme-ultraviolet source

    International Nuclear Information System (INIS)

    Atomic processes in Sn plasmas are investigated for application to extreme-ultraviolet (EUV) light sources used in microlithography. We develop a full collisional radiative (CR) model of Sn plasmas based on calculated atomic data using Hebrew University Lawrence Livermore Atomic Code (HULLAC). Resonance and satellite lines from singly and multiply excited states of Sn ions, which contribute significantly to the EUV emission, are identified and included in the model through a systematic investigation of their effect on the emission spectra. The wavelengths of the 4d-4f+4p-4d transitions of Sn5+ to Sn13+ are investigated, because of their importance for determining the conversion efficiency of the EUV source, in conjunction with the effect of configuration interaction in the calculation of atomic structure. Calculated emission spectra are compared with those of charge exchange spectroscopy and of laser produced plasma EUV sources. The comparison is also carried out for the opacity of a radiatively heated Sn sample. A reasonable agreement is obtained between calculated and experimental EUV emission spectra observed under the typical condition of EUV sources with the ion density and ionization temperature of the plasma around 1018 cm-3 and 20 eV, respectively, by applying a wavelength correction to the resonance and satellite lines. Finally, the spectral emissivity and opacity of Sn plasmas are calculated as a function of electron temperature and ion density. The results are useful for radiation hydrodynamics simulations for the optimization of EUV sources.

  3. Modification of the cellular heat sensitivity of cucumber by growth under supplemental ultraviolet-B radiation

    International Nuclear Information System (INIS)

    The effect of ultraviolet B (UV-B) radiation on the thermal sensitivity of cucumber (Cucumis sativus L.) was studied using UV-B-sensitive cv Poinsett 76 and UV-B-resistant cv Ashley grown under control and elevated (300 mW m-2) UV-B radiation levels. Using both cotyledon and leaf discs, the ability of the tissue to reduce triphenyl tetrazolium chloride (TTC) was determined after treatment at 50 degrees C for various times. Semilogarithmic plots of TTC reduction as a function of time at 50 degrees were curvilinear. They were monophasic for the control cucumber and biphasic for cucumber grown in the presence of elevated UV-B. Treatment of cucumber plants at 37 degrees C for 24 h or of tissue discs at acute UV-B levels for 1 h further modified their response to elevated temperature. These results suggest that growth of cucumber under enhanced UV-B radiation levels increased its ability to withstand elevated temperatures. 19 refs., 2 figs., 2 tabs

  4. Modeling the survivability of brucella to exposure of Ultraviolet radiation and temperature

    Science.gov (United States)

    Howe, R.

    Accumulated summation of daily Ultra Violet-B (UV-B = 290? to 320 ? ) data? from The USDA Ultraviolet Radiation Monitoring Program show good correlation (R^2 = 77%) with daily temperature data during the five month period from February through June, 1998. Exposure of disease organisms, such as brucella to the effects of accumulated UV-B radiation, can be modeled for a 5 month period from February through June, 1998. Estimates of a lethal dosage for brucell of UV-B in the environment is dependent on minimum/maximum temperature and Solar Zenith Angle for the time period. The accumulated increase in temperature over this period also effects the decomposition of an aborted fetus containing brucella. Decomposition begins at some minimum daily temperature at 27 to 30 degrees C and peaks at 39 to 40C. It is useful to view the summation of temperature as a threshold for other bacteria growth, so that accumulated temperature greater than some value causes decomposition through competition with other bacteria and brucella die from the accumulated effects of UV-B, temperature and organism competition. Results of a study (Cook 1998) to determine survivability of brucellosis in the environment through exposure of aborted bovine fetuses show no one cause can be attributed to death of the disease agent. The combination of daily increase in temperature and accumulated UV-B radiation reveal an inverse correlation to survivability data and can be modeled as an indicator of brucella survivability in the environment in arid regions.

  5. Association of amphibians with attenuation of ultraviolet-b radiation in montane ponds

    Science.gov (United States)

    Adams, M.J.; Schindler, D.E.; Bury, B.R.

    2001-01-01

    Ambient ultraviolet-b (UV-B) radiation (280-320 nm) has increased at north-temperate latitudes in the last two decades. UV-B can be detrimental to amphibians, and amphibians have shown declines in some areas during this same period. We documented the distribution of amphibians and salmonids in 42 remote, subalpine and alpine ponds in Olympic National Park, Washington, United States. We inferred relative exposure of amphibian habitats to UV-B by estimating the transmission of 305- and 320-nm radiation in pond water. We found breeding Ambystoma gracile, A. macrodactylum and Rana cascadae at 33%, 31%, and 45% of the study sites, respectively. Most R. cascadae bred in fishless shallow ponds with relatively low transmission of UV-B. The relationship with UV-B exposure remained marginally significant even after the presence of fish was included in the model. At 50 cm water depth, there was a 55% reduction in incident 305-nm radiation at sites where breeding populations of R. cascadae were detected compared to other sites. We did not detect associations between UV-B transmission and A. gracile or A. macrodactylum. Our field surveys do not provide evidence for decline of R. cascadae in Olympic National Park as has been documented in Northern California, but are consistent with the hypothesis that the spatial distribution of R. cascadae breeding sites is influenced by exposure to UV-B. Substrate or pond depth could also be related to the distribution of R. cascadae in Olympic National Park.

  6. Effects of the ultraviolet-B radiation (UV-B) on conifers: a review

    International Nuclear Information System (INIS)

    The current knowledge on conifer responses to enhanced ultraviolet-B (UV-B) radiation is mainly based on greenhouse or growth chamber experiments of one growing season in duration. However, the biomass losses observed in greenhouses do not occur in field-grown trees in their natural habitats. Moreover, the majority of the 20 conifer species studied have been 1-year-old seedlings, and no studies have been undertaken on mature trees. Fully grown needles, with their glaucous waxy surfaces and thick epidermal cells with both soluble and wall-bound UV-B screening metabolites, are well protected against UV-B radiation. However, it is not known whether these are sufficient protectants in young emerging needles or during the early spring period of high UV-B levels reflected from snow. In order to understand all the mechanisms that result in the protection of conifer needles against UV-B radiation, future research should focus on the epidermal layer, separating the waxes, cuticle and epidermal and hypodermal cells. Parallel studies should consist of wall-bound and soluble secondary metabolite analysis, antioxidant measurements and microscopic observations. (author)

  7. Impact of Solar Ultraviolet-B Radiation on the Proteome in Soybean Lines Differing in Flavonoid Contents

    Science.gov (United States)

    Two-dimensional polyacrylamide gel electrophoresis (2D PAGE) was used to systematically investigate the impact of solar ultraviolet-B (UV-B) radiation on the soybean leaf proteome. Two isolines of the Clark cultivar, the standard line with moderate levels of flavonoids and the magenta line with red...

  8. Photoacclimation modulates excessive photosynthetically active and ultraviolet radiation effects in a temperate and an Antarctic marine diatom

    NARCIS (Netherlands)

    van de Poll, W.H.; Alderkamp, A.C.; Janknegt, P.J.; Roggeveld, J; Buma, A.G.J.

    2006-01-01

    The influence of photoacclimation on the effects of excessive photosynthetically active (PAR; 400-700 nm) and ultraviolet (UVR; 280-400 nm) radiation was assessed for the marine diatoms Thalassiosira weissflogii (Grunow) Fryxell and Hasle and Thalassiosira antarctica (Comber). Low and high PAR accli

  9. The effects of ultraviolet radiation on the planktonic community of a shallow, eutrophic estuary: results of mesocosm experiments

    NARCIS (Netherlands)

    Forster, R.M.; Schubert, H.

    2001-01-01

    This paper describes the results of pelagic mesocosm experiments designed to test the effects of enhanced and reduced ultraviolet radiation (UV) on the planktonic community of a Baltic Sea estuary. The Darss-Zingst estuary consists of a series of brackish lagoons with high concentrations of chloroph

  10. Nonthermal radiative transfer of oxygen 98.9 nm ultraviolet emission: Solving an old mystery

    Science.gov (United States)

    Hubert, B.; Gérard, J.-C.; Shematovich, V. I.; Bisikalo, D. V.; Chakrabarti, S.; Gladstone, G. R.

    2015-12-01

    Sounding rocket measurements conducted in 1988 under high solar activity conditions revealed that the intensity of thermospheric OI emissions at 98.9 nm presents an anomalous vertical profile, showing exospheric intensities much higher than expected from radiative transfer model results, which included the known sources of excited oxygen. All attempts based on modeling of the photochemical processes and radiative transfer were unable to account for the higher than predicted brightnesses. More recently, the SOHO-Solar Ultraviolet Measurements of Emitted Radiation instrument measured the UV solar flux at high-spectral resolution, revealing the importance of a significant additional source of oxygen emission at 98.9 nm that had not been accounted for before. In this study, we simulate the radiative transfer of the OI-98.9 nm multiplet, including the photochemical sources of excited oxygen, the resonant scattering of solar photons, and the effects of nonthermal atoms, i.e., a population of fast-moving oxygen atoms in excess of the Maxwellian distribution. Including resonance scattering of the 98.9 nm solar multiplet, we find good agreement with the previous sounding rocket observation. The inclusion of a nonthermal oxygen population with a consistent increase of the total density produces a larger intensity at high altitude that apparently better accounts for the observation, but such a correction cannot be demonstrated given the uncertainties of the observations. A good agreement between model and sounding rocket observation is also found with the triplet at 130.4 nm. We further investigate the radiative transfer of the OI-98.9 nm multiplet and the oxygen emissions at 130.4 and 135.6 nm using observations from the STP78-1 satellite. We find a less satisfying agreement between the model and the STP78-1 data that can be accounted for by scaling the modeled intensity within a range acceptable given the uncertainties on the STP78-1 absolute calibration.

  11. Direct thermoluminescence of sintered ZrO2 pellets induced by ultraviolet radiation

    International Nuclear Information System (INIS)

    The direct thermoluminescence (TL) of ZrO2 after ultraviolet (u.v.) irradiation has been studied systematically. ZrO2 powder was pressed into pellets by cold pressing and sintered at 1100oC. The TL glow curve of ZrO2 induced by u.v. radiation showed prominent peaks at 70, 100 and 235oC, respectively. The fading properties of the TL glow and the proper ranges of exposure for measuring u.v. radiation with ZrO2 have been investigated. The results reveal that the 235oC peak is a better choice for u.v. dosimetry than the other two peaks. A thermoluminescence response was found for u.v. radiation of wavelengths from 253 to 365 nm and also some u.v. radiation in our daily life such as from terrestrial sunlight, tungsten filament bulbs and fluorescent lamps, but almost no response in the visible or longer wavelength regions. Of radiation of wavelength 253, 302 and 365 nm, for the same exposures, the 302 nm wavelength induced the highest TL. This phenomenon cannot be explained by the theory of a 4.9 eV band gap in ZrO2 as proposed by others previously. Our results suggest that the band gap of ZrO2 could be around 4.1 eV, corresponding to the 302 nm photon energy. The results show that ZrO2 has the potential to be used as a u.v. dosimeter in environmental as well as in personnel dosimetry. (author)

  12. Effect of gamma radiation on some artificial blood substitutes

    International Nuclear Information System (INIS)

    Effects of gamma irradiation of dextran 40,000 and 70,000 with doses of 0.5-4.5 Mrad were investigated. The powdered dextran samples were irradiated in glass vessels. The samples were dried before or after the exposure to radiation. There were determined changes in pH, reducing, buffer capacity, colouration, viscosity of the whole preparations, and viscosity of particular fractions separated by column chromatography. Thin-layer chromatography was used to check the irradiated samples for presence of simple sugars. Radioresistance of dextran preparations proved to be enhanced by drying before the exposure. (author)

  13. Medical Devices; General Hospital and Personal Use Devices; Classification of the Ultraviolet Radiation Chamber Disinfection Device. Final order.

    Science.gov (United States)

    2015-11-20

    The Food and Drug Administration (FDA or the Agency) is classifying the ultraviolet (UV) radiation chamber disinfection device into class II (special controls). The special controls that will apply to the device are identified in this order and will be part of the codified language for the UV radiation chamber disinfection device classification. The Agency is classifying the device into class II (special controls) in order to provide a reasonable assurance of safety and effectiveness of the device. PMID:26595943

  14. Spatiotemporal characteristics of ultraviolet radiation in recent 54 years from measurements and reconstructions over the Tibetan Plateau

    Science.gov (United States)

    Liu, H.; Hu, B.; Zhang, L.; Wang, Y. S.; Tian, P. F.

    2016-07-01

    Based on measurements of ultraviolet radiation (UV) for the period of 2005-2014 that were obtained from the Chinese Ecosystem Research Network, we developed an efficient model to estimate UV radiation under various sky conditions. This model can provide an accurate reconstruction of UV radiation data with absolute mean bias error less than 9.65%. We combined this reconstruction model with a hybrid model to obtain the historical data set of daily UV radiation from 1961 to 2014 at 37 weather stations belonging to the China Meteorological Administration over the Tibetan Plateau (TP). Based on the historical data set, the spatial distribution and temporal variation of UV radiation over the TP region were discussed. The decreasing and increasing periods of ultraviolet radiation over the TP were significantly different from those over the entire China. There was an increasing trend in UV radiation over the TP from 1961 to 1983, followed by a decreasing one until 2014, while UV radiation decreased from 1961 to 1989 and then increased slightly after 1989 for the entire China. The average UV radiation values in the increasing and decreasing periods over the TP were 0.598 MJ · m-2 · d-1 and 0.594 MJ · m-2 · d-1, respectively. In addition, aerosol optical depth, column ozone, and cloud prevent approximately 7.13%, 1.31%, and 15.05% of UV radiation reaching the Earth's surface, respectively.

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

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Fabianne, E-mail: fabianne@ua.pt [Department of Biology and Centre for Environmental and Marine Studies (CESAM), University of Aveiro, 3810-193 Aveiro (Portugal); Ferreira, Nuno C.G.; Ferreira, Abel; Soares, Amadeu M.V.M.; Loureiro, Susana [Department of Biology and Centre for Environmental and Marine Studies (CESAM), University of Aveiro, 3810-193 Aveiro (Portugal)

    2011-03-15

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

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

    International Nuclear Information System (INIS)

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

  17. Mass loss and chemical structures of wheat and maize straws in response to ultraviolet-B radiation and soil contact

    OpenAIRE

    Zhou, Guixiang; Zhang, Jiabao; Mao, Jingdong; Zhang, Congzhi; Chen, Lin; Xin, Xiuli; Zhao, Bingzi

    2015-01-01

    The role of photodegradation, an abiotic process, has been largely overlooked during straw decomposition in mesic ecosystems. We investigated the mass loss and chemical structures of straw decomposition in response to elevated UV-B radiation with or without soil contact over a 12-month litterbag experiment. Wheat and maize straw samples with and without soil contact were exposed to three radiation levels: a no-sunlight control, ambient solar UV-B, and artificially elevated UV-B radiation. A b...

  18. Low-level red laser therapy alters effects of ultraviolet C radiation on Escherichia coli cells

    Directory of Open Access Journals (Sweden)

    K.S. Canuto

    2015-01-01

    Full Text Available Low-level lasers are used at low power densities and doses according to clinical protocols supplied with laser devices or based on professional practice. Although use of these lasers is increasing in many countries, the molecular mechanisms involved in effects of low-level lasers, mainly on DNA, are controversial. In this study, we evaluated the effects of low-level red lasers on survival, filamentation, and morphology of Escherichia coli cells that were exposed to ultraviolet C (UVC radiation. Exponential and stationary wild-type and uvrA-deficient E. coli cells were exposed to a low-level red laser and in sequence to UVC radiation. Bacterial survival was evaluated to determine the laser protection factor (ratio between the number of viable cells after exposure to the red laser and UVC and the number of viable cells after exposure to UVC. Bacterial filaments were counted to obtain the percentage of filamentation. Area-perimeter ratios were calculated for evaluation of cellular morphology. Experiments were carried out in duplicate and the results are reported as the means of three independent assays. Pre-exposure to a red laser protected wild-type and uvrA-deficient E. coli cells against the lethal effect of UVC radiation, and increased the percentage of filamentation and the area-perimeter ratio, depending on UVC fluence and physiological conditions in the cells. Therapeutic, low-level red laser radiation can induce DNA lesions at a sub-lethal level. Consequences to cells and tissues should be considered when clinical protocols based on this laser are carried out.

  19. THE EFFECTS OF ULTRAVIOLET-B RADIATION ON ANTARCTIC SEA-ICE ALGAE(1).

    Science.gov (United States)

    Ryan, Ken G; McMinn, Andrew; Hegseth, Else N; Davy, Simon K

    2012-02-01

    The impacts of ultraviolet-B radiation (UVB) on polar sea-ice algal communities have not yet been demonstrated. We assess the impacts of UV on these communities using both laboratory experiments on algal isolates and by modification of the in situ spectral distribution of the under-ice irradiance. In the latter experiment, filters were attached to the upper surface of the ice so that the algae were exposed in situ to treatments of ambient levels of PAR and UV radiation, ambient radiation minus UVB, and ambient radiation minus all UV. After 16 d, significant increases in chl a and cell numbers were recorded for all treatments, but there were no significant differences among the different treatments. Bottom-ice algae exposed in vitro were considerably less tolerant to UVB than those in situ, but this tolerance improved when algae were retained within a solid block of ice. In addition, algae extracted from brine channels in the upper meter of sea ice and exposed to PAR and UVB in the laboratory were much more tolerant of high UVB doses than were any bottom-ice isolates. This finding indicates that brine algae may be better adapted to high PAR and UVB than are bottom-ice algae. The data indicate that the impact of increased levels of UVB resulting from springtime ozone depletion on Antarctic bottom-ice communities is likely to be minimal. These algae are likely protected by strong UVB attenuation by the overlying ice and snow, by other inorganic and organic substances in the ice matrix, and by algal cells closer to the surface. PMID:27009652

  20. Applying spaceborne reflectivity measurements for calculation of the solar ultraviolet radiation at ground level

    Directory of Open Access Journals (Sweden)

    P. N. den Outer

    2012-12-01

    Full Text Available Long-term analysis of cloud effects on ultraviolet (UV radiation on the ground using spaceborne observations requires the use of instruments that have operated consecutively. The longest data record can be built from the reflectivity measurements produced by the instruments Total Ozone Mapping Spectrometers (TOMS flown on Nimbus 7 from 1979 to 1992, TOMS on Earth Probe from 1996 to 2005, and the Ozone Monitoring Instrument (OMI flown on EOS Aura since 2004. The reflectivity data produced by TOMS on Earth Probe is only included until 2002. A comparison is made with cloud effects inferred from ground-based pyranometer measurements at over 83 World Radiation Data Centre stations. Modelled UV irradiances utilizing the standard reflectivity are compared with measurements of UV irradiances at eight European low-elevation stations. The reflectivity data of the two TOMS instruments shows a consistent agreement, and the required corrections are of low percentage, i.e. 2–3%. In contrast, the reflectivity product of OMI requires correction of 7–10%, and a solar angle dependency therein is more pronounced. These corrections were inferred from a comparison with pyranometer data, and tested using the UV measurements. The average reduction of UV radiation due to clouds for all sites together indicates a small trend: a diminishing cloudiness, in line with ground-based UV observations. Uncorrected implementation of the reflectivity data would have indicated the opposite.

    An optimal area was established for reflectivity data for the calculation of daily sums of UV radiation. It measures approximately 1.25° in latitudinal direction for square-shaped areas overhead the ground-based UV stations. Such an area can be traversed within 5 to 7 h at the average wind speeds found for the West European continent.

  1. Low-level red laser therapy alters effects of ultraviolet C radiation on Escherichia coli cells

    International Nuclear Information System (INIS)

    Low-level lasers are used at low power densities and doses according to clinical protocols supplied with laser devices or based on professional practice. Although use of these lasers is increasing in many countries, the molecular mechanisms involved in effects of low-level lasers, mainly on DNA, are controversial. In this study, we evaluated the effects of low-level red lasers on survival, filamentation, and morphology of Escherichia coli cells that were exposed to ultraviolet C (UVC) radiation. Exponential and stationary wild-type and uvrA-deficient E. coli cells were exposed to a low-level red laser and in sequence to UVC radiation. Bacterial survival was evaluated to determine the laser protection factor (ratio between the number of viable cells after exposure to the red laser and UVC and the number of viable cells after exposure to UVC). Bacterial filaments were counted to obtain the percentage of filamentation. Area-perimeter ratios were calculated for evaluation of cellular morphology. Experiments were carried out in duplicate and the results are reported as the means of three independent assays. Pre-exposure to a red laser protected wild-type and uvrA-deficient E. coli cells against the lethal effect of UVC radiation, and increased the percentage of filamentation and the area-perimeter ratio, depending on UVC fluence and physiological conditions in the cells. Therapeutic, low-level red laser radiation can induce DNA lesions at a sub-lethal level. Consequences to cells and tissues should be considered when clinical protocols based on this laser are carried out. (author)

  2. Low-level red laser therapy alters effects of ultraviolet C radiation on Escherichia coli cells

    Energy Technology Data Exchange (ETDEWEB)

    Canuto, K.S.; Guimaraes, O.R.; Geller, M. [Centro Universitario Serra dos Orgaos, Teresopolis, RJ (Brazil). Centro de Ciencias da Saude; Sergio, L.P.S. [Instituto de Biologia Roberto Alcantara Gomes, Rio de Janeiro, RJ (Brazil). Departamento de Biofisica e Biometria; Paoli, F. [Universidade Federal de Juiz de Fora (UFJF), Juiz de Fora, MG (Brazil). Departamento de Morfologia; Fonseca, A.S., E-mail: adnfonseca@ig.com.br [Universidade Federal do Estado do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil). Departamento de Ciencias Fisiologicas

    2015-10-15

    Low-level lasers are used at low power densities and doses according to clinical protocols supplied with laser devices or based on professional practice. Although use of these lasers is increasing in many countries, the molecular mechanisms involved in effects of low-level lasers, mainly on DNA, are controversial. In this study, we evaluated the effects of low-level red lasers on survival, filamentation, and morphology of Escherichia coli cells that were exposed to ultraviolet C (UVC) radiation. Exponential and stationary wild-type and uvrA-deficient E. coli cells were exposed to a low-level red laser and in sequence to UVC radiation. Bacterial survival was evaluated to determine the laser protection factor (ratio between the number of viable cells after exposure to the red laser and UVC and the number of viable cells after exposure to UVC). Bacterial filaments were counted to obtain the percentage of filamentation. Area-perimeter ratios were calculated for evaluation of cellular morphology. Experiments were carried out in duplicate and the results are reported as the means of three independent assays. Pre-exposure to a red laser protected wild-type and uvrA-deficient E. coli cells against the lethal effect of UVC radiation, and increased the percentage of filamentation and the area-perimeter ratio, depending on UVC fluence and physiological conditions in the cells. Therapeutic, low-level red laser radiation can induce DNA lesions at a sub-lethal level. Consequences to cells and tissues should be considered when clinical protocols based on this laser are carried out. (author)

  3. Conidioma production of the white root rot fungus [Rosellinia] in axenic culture under near-ultraviolet light radiation

    International Nuclear Information System (INIS)

    Conidiomata of the white root rot fungus were produced in axenic culture under near-ultraviolet light radiation. Pieces of sterilized Japanese pear twigs were placed on 7-day-old oatmeal agar culture in plates. The plates were further incubated for 5 days and then illuminated by near-ultraviolet light. Synnemata developed on the twigs within 5 weeks in 19 of 20 isolates tested, and conidia were observed in 12 of the 19 isolates. The synnemata and conidia produced were morphologically identical to those of Dematophora necatrix

  4. Measuring and prediction of global solar ultraviolet radiation (0295-0385 μ m) under clear and cloudless skies

    International Nuclear Information System (INIS)

    Values of global solar ultraviolet radiation were measured with an ultraviolet radiometer and also predicted with a atmospheric spectral model. The values obtained with the atmospheric spectral model, based physically, were analyzed and compared with experimental values measured in situ. Measurements were performed for different zenith angles in conditions of clear skies in Heredia, Costa Rica. The necessary input data include latitude, altitude, surface albedo, Earth-Sun distance, as well as atmospheric characteristics: atmospheric turbidity, precipitable water and atmospheric ozone. The comparison between measured and predicted values have been successful. (author)

  5. Effects of PGF2α on human melanocytes and regulation of the FP receptor by ultraviolet radiation

    International Nuclear Information System (INIS)

    Prostaglandins are potent lipid hormones that activate multiple signaling pathways resulting in regulation of cellular growth, differentiation, and apoptosis. In the skin, prostaglandins are rapidly released by keratinocytes following ultraviolet radiation and are chronically present in inflammatory skin lesions. We have shown previously that melanocytes, which provide photoprotection to keratinocytes through the production of melanin, express several receptors for prostaglandins, including the PGE2 receptors EP1 and EP3 and the PGF2α receptor FP, and that PGF2α stimulates melanocyte dendricity. We now show that PGF2α stimulates the activity and expression of tyrosinase, the rate-limiting enzyme in melanin synthesis. Analysis of FP receptor regulation showed that the FP receptor is regulated by ultraviolet radiation in melanocytes in vitro and in human skin in vivo. We also show that ultraviolet irradiation stimulates production of PGF2α by melanocytes. These results show that PGF2α binding to the FP receptor activates signals that stimulate a differentiated phenotype (dendricity and pigmentation) in melanocytes. The regulation of the FP receptor and the stimulation of production of PGF2α in melanocytes in response to ultraviolet radiation suggest that PGF2α could act as an autocrine factor for melanocyte differentiation

  6. Molecular Mechanisms of Ultraviolet Radiation-Induced DNA Damage and Repair

    Directory of Open Access Journals (Sweden)

    Rajesh P. Rastogi

    2010-01-01

    Full Text Available DNA is one of the prime molecules, and its stability is of utmost importance for proper functioning and existence of all living systems. Genotoxic chemicals and radiations exert adverse effects on genome stability. Ultraviolet radiation (UVR (mainly UV-B: 280–315 nm is one of the powerful agents that can alter the normal state of life by inducing a variety of mutagenic and cytotoxic DNA lesions such as cyclobutane-pyrimidine dimers (CPDs, 6-4 photoproducts (6-4PPs, and their Dewar valence isomers as well as DNA strand breaks by interfering the genome integrity. To counteract these lesions, organisms have developed a number of highly conserved repair mechanisms such as photoreactivation, base excision repair (BER, nucleotide excision repair (NER, and mismatch repair (MMR. Additionally, double-strand break repair (by homologous recombination and nonhomologous end joining, SOS response, cell-cycle checkpoints, and programmed cell death (apoptosis are also operative in various organisms with the expense of specific gene products. This review deals with UV-induced alterations in DNA and its maintenance by various repair mechanisms.

  7. Growth of antarctic cyanobacteria under ultraviolet radiation: UVA counteracts UVB inhibition

    Energy Technology Data Exchange (ETDEWEB)

    Quesada, A. [Universite Laval, Quebec (Canada)]|[Universidad Autonoma de Madrid (Spain); Mouget, J.L.; Vincent, W.F. [Universite Laval, Quebec (Canada)

    1995-04-01

    A mat-forming cyanobacterium (Phormidium murayi West and West) isolated from an ice-shelf pond in Antarctica was grown under white light combined with a range of UVA and UVB irradiance. The 4-day growth rate decreased under increasing ultraviolet (UV) radiation, with a ninefold greater response to UVB relative to UVA. In vivo absorbance spectra showed that UVA and to a greater extent UVB caused a decrease in phycocyanin/chlorophyll a and an increase in carotenoids/chlorophyll a. The phycocyanin/chlorophyll a ratio was closely and positively correlated to the UVB-inhibited growth rate. Under fixed spectral gradients of UV radiation, the growth inhibition effect was dominated by UVB. However, at specific UVB irradiances the inhibition of growth depended on the ratio of UVB to UVA, and growth rates increased linearly with increasing UVA. These results are consistent with the view that UVB inhibition represents the balance between damage and repair processes that are each controlled by separate wavebands. They also underscore the need to consider UV spectral balance in laboratory and field assays of UVB toxicity. 49 refs., 6 figs.

  8. Attenuation of solar ultraviolet radiation in eutrophic freshwater lakes and ponds

    International Nuclear Information System (INIS)

    Vertical attenuation of underwater ultraviolet radiation [UVR; UVA (320-400 nm) and UVB (280-315 nm) together with photo-synthetically available radiation (PAR, 400-700 nm)] was measured at 22 sites from 5 freshwater bodies of various trophic states. The factors controlling the attenuation of UVR were examined. At all the sites, underwater irradiances decreased almost exponentially with depth and were more attenuated in dimension order from UVB, UVA, to PAR. Substantial variation in attenuation was observed among water bodies. Attenuation depths (Z1%) for UVB ranged from 0.3 m to 1 m in the eutrophic sites, while exceeding 2 m in oligo-mesotrophic ones. Z1% of UVB and that of UVA were 0.5 and 0.9 times the Secchi disk depth, respectively. Attenuation coefficients (m-1) of UVA and UVB showed significantly positive linear correlations with both chlorophyll a and particulate organic carbon concentrations. Dissolved organic carbon (DOC) was weakly correlated with attenuation coefficients of UVA and UVB. This disagrees with previous reports that stated DOC is the major factor controlling underwater UVR. Phytoplankton is considered to be the more important factor controlling the attenuation of underwater UVR in water bodies with high phytoplankton content and low DOC. (author)

  9. Growth of antarctic cyanobacteria under ultraviolet radiation: UVA counteracts UVB inhibition

    International Nuclear Information System (INIS)

    A mat-forming cyanobacterium (Phormidium murayi West and West) isolated from an ice-shelf pond in Antarctica was grown under white light combined with a range of UVA and UVB irradiance. The 4-day growth rate decreased under increasing ultraviolet (UV) radiation, with a ninefold greater response to UVB relative to UVA. In vivo absorbance spectra showed that UVA and to a greater extent UVB caused a decrease in phycocyanin/chlorophyll a and an increase in carotenoids/chlorophyll a. The phycocyanin/chlorophyll a ratio was closely and positively correlated to the UVB-inhibited growth rate. Under fixed spectral gradients of UV radiation, the growth inhibition effect was dominated by UVB. However, at specific UVB irradiances the inhibition of growth depended on the ratio of UVB to UVA, and growth rates increased linearly with increasing UVA. These results are consistent with the view that UVB inhibition represents the balance between damage and repair processes that are each controlled by separate wavebands. They also underscore the need to consider UV spectral balance in laboratory and field assays of UVB toxicity. 49 refs., 6 figs

  10. Photodegradation of two tropical wood species: jatoba (Hymenaea courbaril) and tauari (Couratari oblongifolia) submitted to ultraviolet radiation

    International Nuclear Information System (INIS)

    The objective of this study was to follow the process of photodegradation of the natural color of wood surface of two tropical species when exposed to ultraviolet radiation. It were used the wood of jatobá (Hymenaea courbaril) with reddish brown coloration, and tauari (Couratari oblongifolia) with yellowish olive coloration. Samples of these woods were subjected to four cycles of ultraviolet radiation (UV) amounting to a total of 168 hours of irradiation and at 350 nm of wave length. Changes of the woods natural color, indicative of the photodegradation process, was monitored by spectrocolorimetry. Both species underwent changes in color caused by photodegradation, since the irradiation caused darkening which was quantified by the intensity of reflected light. Tauari demonstrated greater resistance to UV radiation and jatobá showed greater tendency to redden up. Both species were classified as woods with very appreciable variation in color

  11. Radiological Impact of artificial and naturally radiation sources. Report of the UNSCEAR, 2008

    International Nuclear Information System (INIS)

    Results in the report of the Scientific Committee of the United Nations for Study of the Effects of Atomic Radiations, presented in the 56th period of sessions in July 2008; values obtained from natural sources or from artificial ones are compared and, in accordance with their effects on humans. It is concluded that the most significant change in the situation, between reports, has been the increase in the medical exposure due to the increase in the number of computed tomography examinations. (author)

  12. Minor long-term effects of ultraviolet-B radiation on methane dynamics of a subarctic fen in Northern Finland

    DEFF Research Database (Denmark)

    Mörsky, Sami K.; Haapala, Jaana K.; Rinnan, Riikka;

    2012-01-01

    The effects of elevated ultraviolet-B (UVB) radiation on methane dynamics was studied in a natural fen in Northern Finland for three growing seasons (2003–2005). This is the first in situ study on the effects of elevated UV-B radiation on methane dynamics in a natural fen. The experimental setup....... The results emphasize the need for long-term field studies under moderately enhanced exposures to estimate whether the function and feedbacks of mire ecosystems change under increased UV-B radiation....

  13. Advanced Treatment of Wastewater from UASB Reactor by Microfiltration Membrane Associated With Disinfection by Ultraviolet Radiation

    Directory of Open Access Journals (Sweden)

    André Aguiar Battistelli

    2016-03-01

    Full Text Available The low efficiency of UASB bioreactors, regarding the removal of nutrient, organic matter and pathogens, makes it necessary to carry out a post treatment, in order to improve the quality of the effluent. Accordingly, this research has examined the use of microfiltration associated to the disinfection by the ultraviolet radiation, as an option to this post treatment. For so, were collected samples of UASB reactors’ effluent, in order to carry out some tests on a pilot microfiltration system, using in one of the samples pre-coagulation with vegetable tannin. After, all the microfiltrated samples were inserted in a UV reactor, applying different radiation doses, ranging from 43.8 to 194.9 mWs.cm-2, to simulate the disinfection. The system used showed good results in terms of turbidity removal, apparent color, true color, phosphorus, nitrogen, total solids, total suspended solids and COD, reaching in the best operating condition, the following values: 1.90 uT, 15 uC, 10 uC, 0.94 mg/L, 17.64 mg/L, 123 mg/L, 0 mg/L and 10 mg/L, respectively, which represent the following removal percentages: 91.3%, 93.6%, 82.0%, 55.1%, 26.3%, 35% and 86.1%. The inactivation obtained for E. coli, total coliforms, colifagos and Clostridium perfrigens was satisfactory, achieving a higher inactivation than the detection limit of the method used, when submitted to the highests tested radiation doses. The average permeate flux ranged from 55.2 to 133.6 L.m-2.h-1.

  14. Ultraviolet radiation B induces differentiation and protein kinase C in normal human epidermal keratinocytes

    International Nuclear Information System (INIS)

    Mid-wave ultraviolet radiation (UVB, 280-320 nm) is highly efficient at inducing erythema, pyrimidine dimers in DNA, oncogene expression and initiation of cutaneous tumors. These UVB-induced responses of epidermal cells have been correlated with the direct effects of UVB on DNA. However, UVB has also been shown to have biologic effects at the cellular level that appear to mimic some of the membrane-associated effects produced by phorbol ester tumor promoters such as 12-O-tetradecanoyl phorbol-13-acetate (TPA). For example, we have previously shown that both UVB irradiation and TPA treatment are followed by release of arachidonic acid and a rapid, dose-dependent inhibition of epidermal growth factor (EGF) binding. TPA generates cellular responses through activation of a phospholipid-dependent, calcium-sensitive protein kinase, protein kinase C (PKC). The primary goal of the studies described here was to compare the cellular effects of TPA with those of UVB with special regard to PKC and keratinocyte growth control, using normal human epidermal keratinocytes. The results obtained showed that both TPA and UVB radiation induced differentiation in normal human keratinocytes. UVB radiation, however, increased both cytosolic and membrane-associated levels of PKC, in contrast to TPA, which increased PKC primarily in the membrane fraction. PCK is probably not the initial chromophore or target molecule of UVB, but because activation of PKC has been shown to be essential for keratinocyte differentiation, differentiation induced by UVB may be caused by activation of PKC by UVB-induced release of diacylglycerol or arachidonic acid. (au) 25 refs

  15. Ultraviolet - status of knowledge on exposure and health risks

    International Nuclear Information System (INIS)

    After having recalled some physical aspects of ultraviolet radiations (presence in solar radiation, artificial UV radiation, measurement, metrology, UV index, boundary limits), this report describes the biological and health effects of UV radiations (analysis methodology, recall of previous expert reports, biological effects, health effects), addresses human behaviour with respect to UV radiation and exposure to UV radiation, discusses the relationship between cosmetics and UV radiation. It presents the various European and international positions with respect to UV emitting devices (evolution of standards, regulations). Some recommendations are made regarding solar exposure, sun-tanning installations, and other domestic or industrial sources

  16. Effects of ultraviolet radiation on the lower levels of the planktonic food web in Antarctica

    International Nuclear Information System (INIS)

    Full text: Most of the studies that investigated the effects of ultraviolet radiation (UVR, 280-400 NM) on the first levels of the marine food web used experimental approaches (in situ incubations, micro and mesocosms). However, research on the responses to UVR of the micro community in their natural environment is scarce. A time series study including most of the oceanographic parameters described as controlling bacteria and phytoplankton dynamics was carried out (PAR, tidal mixing, turbulent mixing by winds and currents, nutrient stress). In this case, however, the effects of ultraviolet A and B (UVB, 280-320 nm and UVA, 320-400 nm, respectively) were added as forcing parameters. Fieldwork was done in the vicinity of Melchior Station (64 degrees 20' S, 62 degrees 59' W, Observatory Island). It involved the automated measurement of physical variables (currents, tides and meteorological data), as well as discrete sampling of physical (salinity, temperature), chemical (macro nutrients) and biological variables (bacterial and phytoplankton abundance and production, PSI I system, photo protective compounds). Sub-surface sampling (0.5 m depth) was conducted with 5 L Niskin bottles at a fixed station (sampling every 6/12 h centered at local noon during the whole study period), and vertical profiles at 6 fixed depths (0, 5, 10, 20, 30 and 50 m) were done every four days. The whole study lasted for one month, from February 11 to March 12 2002. Average upper mixed layer (UML) was around 20 m and the depth of the euphotic zone (1% of incident radiation) for UVB and UVA was respectively 17 and 32 m, suggesting a strong influence of UVR on cells within the UML. PSII activity showed a significant inverse correlation with UVB, phased with irradiance oscillations. Bacterio plankton and phytoplankton biomass and production of both presented a similar response, but minimum values were lagged by 4-6 h from UVR maxima. Mycosporin like aminoacids (MAA's) were also phased and directly

  17. Antioxidant activity stimulated by ultraviolet radiation in the nervous system of a crustacean

    International Nuclear Information System (INIS)

    Highlights: • Ultraviolet (UV) radiation produces biological damage, principally oxidative stress. • We analyzed oxidative stress in the central nervous system (CNS) of a crab. • The damage was evaluated using biochemical tests and immunohistochemistry. • We verified the occurrence of apoptosis in the brain of the UV-exposed crabs. • Environmental doses of UV can cause oxidative damage to CNS, including apoptosis. - Abstract: Ultraviolet (UV) radiation can produce biological damage, principally oxidative stress, by increasing the production of reactive oxygen species (ROS). This study evaluated biochemical impairments related to the oxidative stress induced by UVA, UVB and UVA + UVB (solar simulator-SIM) in environmental doses, during five consecutive days of exposure, in the brain and eyestalk of the crab Ucides cordatus. We evaluated these regions by sampling on the 1st, 3rd and 5th days of UV exposure for lipid peroxidation (LPO), antioxidant capacity against the peroxyl radical (ACAP), and the activities of catalase (CAT), glutathione peroxidase (GPX) and glutathione-S-transferase (GST). Immunohistochemical and immunoblotting assays were performed for anti-activated-caspase 3 in the brains. After the first day of exposure, LPO increased in the eyestalks and brains of the UV-exposed animals; ACAP, and CAT, GPX and GST activities also increased in the brains. On the third day, the LPO values in the eyestalk remained high in the UV-exposed groups, while ACAP decreased in the brain and eyestalk and CAT activity remained high in all irradiated groups in both regions. On the fifth day, LPO decreased in the eyestalk and brain of the UV-exposed groups. These results may have been a consequence of the antioxidant defense system (ADS) activity, since CAT activity was high in both regions, ACAP was high in the eyestalks of the SIM group, and GPX activity remained high in the eyestalks of the UVA and UVB groups. Immunohistochemical assays and immunoblotting

  18. Antioxidant activity stimulated by ultraviolet radiation in the nervous system of a crustacean

    Energy Technology Data Exchange (ETDEWEB)

    Hollmann, Gabriela, E-mail: gabrielahollmann@biof.ufrj.br [Programa de Pós Graduação em Ciências Biológicas-Fisiologia, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro-UFRJ, Rio de Janeiro, RJ 21941-590 (Brazil); Ferreira, Gabrielle de Jesus, E-mail: gabi_ferreiira@hotmail.com [Programa de Pós Graduação em Ciências Biológicas-Fisiologia, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro-UFRJ, Rio de Janeiro, RJ 21941-590 (Brazil); Geihs, Márcio Alberto, E-mail: geihs@hotmail.com [Programa de Pós Graduação em Ciências Fisiológicas-Fisiologia Animal Comparada. Instituto de Ciências Biológicas, Universidade Federal do Rio Grande-FURG, Rio Grande, RS 96201-900 (Brazil); Vargas, Marcelo Alves, E-mail: biovargas@gmail.com [Programa de Pós Graduação em Ciências Fisiológicas-Fisiologia Animal Comparada. Instituto de Ciências Biológicas, Universidade Federal do Rio Grande-FURG, Rio Grande, RS 96201-900 (Brazil); and others

    2015-03-15

    Highlights: • Ultraviolet (UV) radiation produces biological damage, principally oxidative stress. • We analyzed oxidative stress in the central nervous system (CNS) of a crab. • The damage was evaluated using biochemical tests and immunohistochemistry. • We verified the occurrence of apoptosis in the brain of the UV-exposed crabs. • Environmental doses of UV can cause oxidative damage to CNS, including apoptosis. - Abstract: Ultraviolet (UV) radiation can produce biological damage, principally oxidative stress, by increasing the production of reactive oxygen species (ROS). This study evaluated biochemical impairments related to the oxidative stress induced by UVA, UVB and UVA + UVB (solar simulator-SIM) in environmental doses, during five consecutive days of exposure, in the brain and eyestalk of the crab Ucides cordatus. We evaluated these regions by sampling on the 1st, 3rd and 5th days of UV exposure for lipid peroxidation (LPO), antioxidant capacity against the peroxyl radical (ACAP), and the activities of catalase (CAT), glutathione peroxidase (GPX) and glutathione-S-transferase (GST). Immunohistochemical and immunoblotting assays were performed for anti-activated-caspase 3 in the brains. After the first day of exposure, LPO increased in the eyestalks and brains of the UV-exposed animals; ACAP, and CAT, GPX and GST activities also increased in the brains. On the third day, the LPO values in the eyestalk remained high in the UV-exposed groups, while ACAP decreased in the brain and eyestalk and CAT activity remained high in all irradiated groups in both regions. On the fifth day, LPO decreased in the eyestalk and brain of the UV-exposed groups. These results may have been a consequence of the antioxidant defense system (ADS) activity, since CAT activity was high in both regions, ACAP was high in the eyestalks of the SIM group, and GPX activity remained high in the eyestalks of the UVA and UVB groups. Immunohistochemical assays and immunoblotting

  19. DEFINITION DESIRED MODE ULTRAVIOLET RADIATION, WHICH PREVENT MYCOBACTERIUM TUBERCULOSIS SURVIVAL AND CONVERSION TO L-FORMS

    Directory of Open Access Journals (Sweden)

    Moiseenko TN

    2015-04-01

    Full Text Available Bactericidal effect of ultraviolet (UV rays was first described over 100 years ago. UV was used in hospitals from 1930 and in 1936 was first used to sterilize the air in the operating room. The maximum bactericidal effect occurs in the region 254-257 nm UV wavelength, which is manifested mainly in the destructive-modifying photochemical damage of DNA synthesis. So, UV rays causes an increase in the permeability of the microbial cell membranes to ions environment and coagulation of colloids cytoplasm, resulting in disruption of normal cell development, stopping the reproduction and lysis. In any body there are biochemical mechanisms that could fully or partially restore the damaged original structure of the DNA molecule - fotoreactivation. It's resistant microorganisms consist about 0.01% of the microbial population, but the certain types reach 1-5%. Surviving bacteria can form new colonies with less susceptibility to radiation. Mycobacteria in the course of evolution developed various mechanisms to overcome or inactivation of adverse environmental factors: a special cell wall (waxes, fats, mycolic acid; large metabolic capabilities by which M. tuberculosis able to inactivate various antiseptics and disinfectants; morphological plasticity, which is spontaneous and induced transformation in L-forms with a reversion of virulent original shape. М. tuberculosis more resistant to UV radiation than other bacteria. Materials and methods. We investigated the effectiveness of UV radiation against to M. tuberculosis at distances from the radiator - 70 cm, 140 cm, 210 cm; exposure time 20, 30, 40 and 50 minutes. We used museum strain H37Rv and 3 clinical strains: 1 - strain with preserved sensitivity; 2 - strain with resistance to isoniazid and rifampicin; 3 - strain with resistance to isoniazid, rifampicin and ofloxacin (enhanced resistance. We used radiator - Philips TUV power 30 W (without ozone for up to 6000 hours. Control and irradiated cultures of

  20. Correcting spaceborne reflectivity measurements for application in solar ultraviolet radiation levels calculations at ground level

    Directory of Open Access Journals (Sweden)

    P. N. den Outer

    2012-01-01

    Full Text Available The Lambertian Equivalent Reflection (LER produced by satellite-carried instruments is used to determine cloud effects on ground level UltraViolet (UV radiation. The focus is on data use from consecutive operating instruments: the Total Ozone Mapping Spectrometers (TOMS flown on Nimbus 7 from 1979 to 1992, TOMS on Earth Probe from 1996 to 2005, and the Ozone Monitoring Instrument (OMI flown on Aura since 2004. The LER data produced by TOMS on Earth Probe is only included until 2002. The possibility to use the Radiative Cloud Fraction (RCF-product of OMI is also investigated. A comparison is made with cloud effects inferred from ground-based pyranometer measurements at over 83 World Radiation Data Centre stations. Modelled UV irradiances utilizing LER data are compared with measurements of UV irradiances at eight European low elevation stations. The LER data set of the two TOMS instruments shows a consistent agreement, and the required corrections are of low percentage i.e. 2–3%. In contrast, the LER data of OMI requires correction of 7–10%, and a solar angle dependency therein is more pronounced. These corrections were inferred from a comparison with pyranometer data, and tested using the UV measurements. The RCF product of OMI requires a large correction but can then be implemented as a cloud effect proxy. However, a major drawback of RCF is the large number of clipped data, i.e. 18%, and results are not better than those obtained with the corrected LER product of OMI. The average reduction of UV radiation due to clouds for all sites together indicate a small trend: a diminishing cloudiness, in line with ground-based UV observations. Uncorrected implementation of LER would have indicated the opposite. An optimal field of view of 1.25° was established for LER data to calculate UV radiations levels. The corresponding area can be traversed within 5–7 h at the average wind speeds found for the West European continent.

  1. Terrestrial ecosystems, increased solar ultraviolet radiation, and interactions with other climate change factors.

    Science.gov (United States)

    Caldwell, M M; Bornman, J F; Ballaré, C L; Flint, S D; Kulandaivelu, G

    2007-03-01

    as growth, DNA damage, oxidative damage and induction of changes in secondary chemicals. Thus, use of a single BSWF for plant or ecosystem response is not appropriate. This brief review emphasizes progress since the previous report toward the understanding of solar ultraviolet radiation effects on terrestrial systems as it relates to ozone column reduction and the interaction of climate change factors. PMID:17344961

  2. Effect of ultraviolet radiation on growth and photosynthetic ability of turnip (Brassica campestris L.)

    International Nuclear Information System (INIS)

    Two experimental plots were prepared to investigate the effect of near-ultraviolet (UV) radiation on the growth and photosynthesis of turnip (Brassica cam pestris L.). They were treated by covering with UV-transmitting vinyl film (UVT) or UV-eliminating vinyl film (UVE) (Fig.1). The results were summarized as follows. 1. UV energy in UVE plot was 3 to 4% of that in UVT plot (Table 1). The temperature of UVE plot was similar to that of UVT plot throughout the growth period (Fig.2). The daily mean temperature throughout the growth period was about 19°C. 2. UVE plot was superior to UVT plot in all the characters investigated on growth (Table 2). Particularly plant length and fresh weight were significant at 5% level throughout the growth period. The growth pattern of each character was almost common to each other between the two experimental plots, except that the relative growth rate during exponential growth period of UVE plot was higher than that of UVT plot (Fig.3-1-Fig.6). 3. Apparent photosynthesis rate per unit of leaf area in UVE plot was higher than that in UVT plot at 24 days after sowing, but at 42, 48 and 70 days of after sowing the result was reversed (Fig.8). From this experiment, the effect UV on photosynthesis was not clearly observed. (author)

  3. Green algae in alpine biological soil crust communities: acclimation strategies against ultraviolet radiation and dehydration.

    Science.gov (United States)

    Karsten, Ulf; Holzinger, Andreas

    2014-01-01

    Green algae are major components of biological soil crusts in alpine habitats. Together with cyanobacteria, fungi and lichens, green algae form a pioneer community important for the organisms that will succeed them. In their high altitudinal habitat these algae are exposed to harsh and strongly fluctuating environmental conditions, mainly intense irradiation, including ultraviolet radiation, and lack of water leading to desiccation. Therefore, green algae surviving in these environments must have evolved with either avoidance or protective strategies, as well as repair mechanisms for damage. In this review we have highlighted these mechanisms, which include photoprotection, photochemical quenching, and high osmotic values to avoid water loss, and in some groups flexibility of secondary cell walls to maintain turgor pressure even in water-limited situations. These highly specialized green algae will serve as good model organisms to study desiccation tolerance or photoprotective mechanisms, due to their natural capacity to withstand unfavorable conditions. We point out the urgent need for modern phylogenetic approaches in characterizing these organisms, and molecular methods for analyzing the metabolic changes involved in their adaptive strategies. PMID:24954980

  4. Electrical behavior and vacuum ultraviolet radiation efficiency of monofilamentary xenon dielectric barrier discharges

    International Nuclear Information System (INIS)

    In this paper we report the experimental investigation of a pure xenon monofilamentary dielectric barrier discharge (DBD), using a high voltage power supply. Stable microdischarges were achieved and studied in the pressure range of 100-400 Torr, at frequencies between 10 and 40 kHz. Successive 3 ns exposure time snapshots of the discharge clearly show how it built up. Its diameter was about 0.26 mm. The discharge voltage and current were determined from the measurement of the supply voltage and current. Compared to those in argon, the current pulses were shorter (less than 30 ns, above 200 Torr) and had much higher peak values. Ignition voltages were also higher in the heavier gas. Electrical energy and vacuum ultraviolet radiation energy of the second continuum of xenon were both independent of frequency. They both varied almost linearly with pressure. The measured DBD vuv efficiency of a single xenon microdischarge reported here was between 55% and 60%, and the maximum value was reached for 200 Torr. These values were twice those reported for multifilamentary discharges working with a sinusoidal supply. They were similar to those obtained for multifilamentary dielectric barrier discharges excited with short voltage pulses

  5. In vivo NMR metabolic profiling of Fabrea salina reveals sequential defense mechanisms against ultraviolet radiation.

    Science.gov (United States)

    Marangoni, Roberto; Paris, Debora; Melck, Dominique; Fulgentini, Lorenzo; Colombetti, Giuliano; Motta, Andrea

    2011-01-01

    Fabrea salina is a hypersaline ciliate that is known to be among the strongest ultraviolet (UV)-resistant microorganisms; however, the molecular mechanisms of this resistance are almost unknown. By means of in vivo NMR spectroscopy, we determined the metabolic profile of living F. salina cells exposed to visible light and to polychromatic UV-B + UV-A + Vis radiation for several different exposure times. We used unsupervised pattern-recognition analysis to compare these profiles and discovered some metabolites whose concentration changed specifically upon UV exposure and in a dose-dependent manner. This variation was interpreted in terms of a two-phase cell reaction involving at least two different pathways: an early response consisting of degradation processes, followed by a late response activating osmoprotection mechanisms. The first step alters the concentration of formate, acetate, and saturated fatty-acid metabolites, whereas the osmoprotection modifies the activity of betaine moieties and other functionally related metabolites. In the latter pathway, alanine, proline, and sugars suggest a possible incipient protein synthesis as defense and/or degeneration mechanisms. We conclude that NMR spectroscopy on in vivo cells is an optimal approach for investigating the effect of UV-induced stress on the whole metabolome of F. salina because it minimizes the invasiveness of the measurement. PMID:21190674

  6. Impact of ultraviolet radiation treatments on the quality of freshly prepared tomato (Solanum lycopersicum) juice.

    Science.gov (United States)

    Bhat, Rajeev

    2016-12-15

    Impact of ultraviolet (UV-C) radiation treatments (0, 15, 30 and 60min) on freshly extracted tomato juice quality (physicochemical properties, antioxidant activity and microbial load) was evaluated. On exposure to UV-C, level of water activity, total soluble solids, and titratable acidity exhibited non-significant increase up to 30min of exposure time. Regarding colour analysis, L∗ value significantly increased with subsequent decrease in a∗ and b∗ values post UV-C treatments. Clarity, DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity and total phenolics content significantly increased, whereas ascorbic acid level significantly reduced at 60min of UV-C exposure time. So also, lycopene content exhibited a non-significant decrease after UV-C treatment. Microbial studies showed reduction in total plate count and total mould counts post UV-C treatment. Overall, UV-C treatment being a physical, non-thermal method of food preservation holds the ability to improve or preserve vital quality parameters in freshly prepared tomato juices, and henceforth possesses high scope for commercial exploration. PMID:27451228

  7. Quantifying dust and the ultraviolet radiation-density in the local universe

    CERN Document Server

    Rowan-Robinson, M

    2003-01-01

    A sample of local galaxies for which far infrared and uv fluxes are available is used to estimate the characteristic dust extinction in galaxies and to test whether standard dust properties are plausible. Assuming galaxies can be characterized by a single dust optical depth (certainly not valid for galaxies with a dominant starburst component), the infrared excess and ultraviolet colours of local galaxies are found to be consistent with normal Milky Way dust, with a mean value for E(B-V) of 0.16. A significant fraction of the dust heating is due to older, lower mass stars, and this fraction increases towards earlier galaxy types. Analysis of F_fir/F_uv versus uv colour diagrams for starburst galaxies in terms of a simple screen dust model does not support a Calzetti (1999) rather than a Milky Way extinction law, though the absence of the expected strong 2200 A feature in several galaxies with IUE spectra does show that more detailed radiative transfer models are needed, probably with non-spherical geometry. A...

  8. Cancers in Australia attributable to exposure to solar ultraviolet radiation and prevented by regular sunscreen use

    Science.gov (United States)

    Olsen, Catherine M; Wilson, Louise F; Green, Adele C; Bain, Christopher J; Fritschi, Lin; Neale, Rachel E; Whiteman, David C

    2015-01-01

    Objectives To estimate the proportion and numbers of cancers occurring in Australia attributable to solar ultraviolet radiation (UVR) and the proportion and numbers prevented by regular sun protection factor (SPF) 15+ sunscreen use. Methods We estimated the population attributable fraction (PAF) and numbers of melanomas and keratinocyte cancers (i.e. basal cell carcinomas and squamous cell carcinomas) due to exposure to ambient UVR resulting from residing in Australia versus residing in the UK (for melanoma) or Scandinavia (for keratinocyte cancers). We also estimated the prevented fraction (PF): the proportion of cancers that would have occurred but were likely prevented by regular sunscreen use. Results An estimated 7,220 melanomas (PAF 63%) and essentially all keratinocyte cancers occurring in Australia were attributable to high ambient UVR levels in Australia. We estimated that regular sunscreen use prevented around 14,190 (PF 9.3%) and 1,730 (PF 14%) people from developing SCC and melanoma, respectively. Conclusions Although our approach was conservative, a high proportion of skin cancers in Australia are attributable to high ambient levels of UVR. Prevailing levels of sunscreen use probably reduced skin cancer incidence by 10–15%. Implications Most skin cancers are preventable. Sunscreen should be a component of a comprehensive sun protection strategy. PMID:26437734

  9. Morphological responses of crop and weed species of different growth forms to ultraviolet-B radiation

    International Nuclear Information System (INIS)

    The influence of ultraviolet-B (UV-B) radiation (280-320 nanometers) on the morphology of 12 common dicot and monocot crop or weed species was examined to determine whether any common responses could be found that might, in turn, be useful in predicting possible changes in competitive balance under solar UV-B enhancement. Under glasshouse conditions, UV-B exposure (simulating a 20% reduction in stratospheric ozone at Logan, Utah) was found to reduce leaf blade and internode lengths and increase leaf and axillary shoot production in several species. Overall, the directions of these trends were similar in the majority of species that exhibited a significant response. These morphological changes occurred without any significant reduction in total shoot dry matter production. There was no clear distinction in the response of crops and weeds, though monocots were found to be generally more responsive than dicots. Previous work in dense canopies has shown that the photomorphogenetic effects of UV-B alter leaf placement and thereby influence competition for light. Our results suggest that, under these conditions, changes in competitive balance resulting from increased UV-B might be expected more frequently when monocots are involved in mixtures, rather than mixtures of only dicots

  10. Using an Ongoing Study of Terrestrial Plant Response to Ultraviolet Radiation in Project ALERT

    Science.gov (United States)

    Condon, Estelle; Skiles, J. W.; Seitz, Jeffery C.; Dantoni, Hector L.

    1998-01-01

    The ALERT (Augmented Learning Environment for Renewable Teaching) Project is a cooperative California-based program with two main partners: California State University (CSU) geoscience and education departments and two NASA Centers, the Jet Propulsion Laboratory (JPL) in Pasadena and the Ames Research Center (ARC) in Mountain View. This paper presents an example of how a NASA research effort can be used in the undergraduate classroom. A study, now in the fourth year, subjects test plants to exposures of varying solar ultraviolet (UV) radiation (280 - 340 nm); a full solar UV exposure, a solar UV exposure less about 14% of ambient UV flux, and a UV-blocked regime. This experiment is simple in that only modest amounts of expense are required yet it is elegant since only one variable, UV-flux is involved. The experiment lends itself to teaching several of the Earth Sciences because it uses information from botany, taxonomy, and ecology. Aspects of physics are inherent in the study since portions of the electromagnetic spectrum are studied. Further, since only one of many variables are manipulated, UV flux, the study demonstrates how the scientific method is used in formulating and testing hypotheses. Based on the ALERT experience this summer, this study will be implemented at a CSU campus with the expectation that it will serve as a pedagogical tool and where it will involve students in actual research.

  11. Dopamine efflux in response to ultraviolet radiation in addicted sunbed users.

    Science.gov (United States)

    Aubert, Pamela M; Seibyl, John P; Price, Julianne L; Harris, Thomas S; Filbey, Francesca M; Jacobe, Heidi; Devous, Michael D; Adinoff, Bryon

    2016-05-30

    Compulsive tanning despite awareness of ultraviolet radiation (UVR) carcinogenicity may represent an "addictive" behavior. Many addictive disorders are associated with alterations in dopamine (D2/D3) receptor binding and dopamine reactivity in the brain's reward pathway. To determine if compulsive tanners exhibited neurobiologic responses similar to other addictive disorders, this study assessed basal striatal D2/D3 binding and UVR-induced striatal dopamine efflux in ten addicted and ten infrequent tanners. In a double-blind crossover trial, UVR or sham UVR was administered in separate sessions during brain imaging with single photon emission computerized tomography (SPECT). Basal D2/D3 receptor density and UVR-induced dopamine efflux in the caudate were assessed using (123)I-iodobenzamide ((123)I-IBZM) binding potential non-displaceable (BPnd). Basal BPnd did not significantly differ between addicted and infrequent tanners. Whereas neither UVR nor sham UVR induced significant changes in bilateral caudate BPnd in either group, post-hoc analyses revealed left caudate BPnd significantly decreased (reflecting increased dopamine efflux) in the addicted tanners - but not the infrequent tanners - during the UVR session only. Bilateral ∆BPnd correlated with tanning severity only in the addicted tanners. These preliminary findings are consistent with a stronger neural rewarding response to UVR in addicted tanners, supporting a cutaneous-neural connection driving excessive sunbed use. PMID:27085608

  12. Ultraviolet radiation: effects on risks of prostate cancer and other internal cancers

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Samuel J. [Human Genomics Research Group, Institute of Science and Technology in Medicine and Department of Urology, Keele University School of Medicine, University Hospital of North Staffordshire, Hartshill Campus, Stoke-on-Trent, ST4 7PA Staffordshire (United Kingdom); Fryer, Anthony A. [Human Genomics Research Group, Institute of Science and Technology in Medicine and Department of Urology, Keele University School of Medicine, University Hospital of North Staffordshire, Hartshill Campus, Stoke-on-Trent, ST4 7PA Staffordshire (United Kingdom); Strange, Richard C. [Human Genomics Research Group, Institute of Science and Technology in Medicine and Department of Urology, Keele University School of Medicine, University Hospital of North Staffordshire, Hartshill Campus, Stoke-on-Trent, ST4 7PA Staffordshire (United Kingdom)]. E-mail: paa00@keele.ac.uk

    2005-04-01

    Governmental and research agencies worldwide have strongly advocated sun avoidance strategies in an attempt to counter marked increases in skin cancer incidence. Concurrently, there are reports describing widespread Vitamin D{sub 3} deficiency. Because 1,25-dihydroxyvitamin D{sub 3}, through interaction with the Vitamin D receptor, exerts pleiotrophic effects, such deficiency might be expected to have clinical consequences. Indeed, various reports indicate that exposure to ultraviolet radiation (UVR) exerts a protective effect on development of some common diseases including internal cancers and multiple sclerosis. We describe studies indicating that modest exposure reduces risk of prostate cancer. The effect of UVR is mediated by skin type; at lower levels of exposure a relative inability to effect skin pigmentation is protective presumably because it allows more efficient Vitamin D{sub 3} synthesis. Polymorphic variants in genes associated with pigmentation including melanocyte stimulating hormone receptor and tyrosinase are also associated with prostate cancer risk. Overall, though preliminary and requiring cautious interpretation, these data indicate that moderate UVR exposure together with characteristics linked with less effective tanning confer reduced prostate cancer risk. Clearly, it is important to define safe levels of UVR that do not result in increased risk of skin cancers such as malignant melanoma.

  13. Effects of ultraviolet radiation on the primary production of natural phytoplankton assemblages in Lake Michigan

    International Nuclear Information System (INIS)

    Inhibition of primary production of offshore Lake Michigan phytoplankton assemblages by solar ultraviolet radiation (SUVR) was observed from April to October in 1986 during in situ incubations in special Plexiglas chambers. Inhibition of primary production by SUVR was observed to a depth of 6 m and at intensities which were approximately 1% of the UV-B intensity at the lake surface. Significant inhibition of primary production by SUVR was restricted to the top third of the euphotic zone. The order of relative sensitivities of offshore Lake Michigan phytoplankton assemblages during different seasons to inhibition by SUVR were spring (ED50 = 17.6 kJ/m2 UV-B) > fall (ED50 = 30.5 kJ/m2 UV-B) > summer (ED50 = 131.6 kJ/m2 UV-B). A hazard assessment model predicted a significant reduction (13%) in areal (total water column) primary production for offshore Lake Michigan due to current SUVR intensities. Concern about possible increased reduction of primary production in the North American Great Lakes due to depletion of the stratospheric ozone layer appears to be unwarranted

  14. Hazard of ultraviolet radiation emitted in gas tungsten arc welding of aluminum alloys.

    Science.gov (United States)

    Nakashima, Hitoshi; Utsunomiya, Akihiro; Fujii, Nobuyuki; Okuno, Tsutomu

    2016-03-28

    Ultraviolet radiation (UVR) emitted during arc welding frequently causes keratoconjunctivitis and erythema. The extent of the hazard of UVR varies depending on the welding method and conditions. Therefore, it is important to identify the levels of UVR that are present under various conditions. In this study, we experimentally evaluated the hazard of UVR emitted in gas tungsten arc welding (GTAW) of aluminum alloys. The degree of hazard of UVR is measured by the effective irradiance defined in the American Conference of Governmental Industrial Hygienists guidelines. The effective irradiances measured in this study are in the range 0.10-0.91 mW/cm(2) at a distance of 500 mm from the welding arc. The maximum allowable exposure times corresponding to these levels are only 3.3-33 s/day. This demonstrates that unprotected exposure to UVR emitted by GTAW of aluminum alloys is quite hazardous in practice. In addition, we found the following properties of the hazard of UVR. (1) It is more hazardous at higher welding currents than at lower welding currents. (2) It is more hazardous when magnesium is included in the welding materials than when it is not. (3) The hazard depends on the direction of emission from the arc. PMID:26632121

  15. Skin cancer incidence is highly associated with ultraviolet-B radiation history.

    Science.gov (United States)

    Chang, Ni-Bin; Feng, Rui; Gao, Zhiqiang; Gao, Wei

    2010-09-01

    Recently, the increased amount of ultraviolet-B (UV-B) exposure due to ozone depletion has been found to be associated with increased incidence of skin cancer across the world. The quantification of individual, regional, and historical UV exposure directly affects establishment of the association between skin cancer and UV exposure, but accurate assessment and measurement have been challenging for decades. As a sequence, cumulative studies using different metrics reported conflicting results on whether UV radiation, including sunburns, early childhood sun exposure, and chronic exposure, increases melanoma risk. This paper aims to establish the relationship between UV-B and melanoma incidence across the continental U.S. using an ecological approach that incorporate more accurate UV-B exposure measured by the National Aeronautical and Space Administration Nimbus-7 total ozone mapping spectrometer, and the United State Department of Agriculture ground-based network. Using statistical linear mixed models, we found strong positive associations between the skin cancer and the past UV exposure or the past cumulative 3-year UV exposure 3 or 4 years ago. UV has regional distributions and its regional effects on the skin cancer incidence are still significant after adjusting the effect of UV exposure. Research findings yield deepened understanding of spatiotemporal distribution of melanoma incidence rates and a greater appreciation for the complexity and heterogeneity of melanoma risk factors especially the UV-B exposure at different temporal and spatial scales. PMID:20619731

  16. Use of 8-methoxypsoralen and long-wavelength ultraviolet radiation for decontamination of platelet concentrates

    International Nuclear Information System (INIS)

    Transmission of viral diseases through blood products remains an unsolved problem in transfusion medicine. We have developed a psoralen photochemical system for decontamination of platelet concentrates in which platelets are treated with long wavelength ultraviolet radiation (UVA, 320-400 nm) in the presence of 8-methoxypsoralen (8-MOP). Bacteria, RNA viruses, and DNA viruses ranging in genome size from 1.2 x 10(6) daltons, encompassing the size range of human pathogens, were inoculated into platelet concentrates and subjected to treatment. This system inactivated 25 to 30 logs/h of bacteria Escherichia coli or Staphylococcus aureus, 6 logs/h of bacteriophage fd, 0.9 log/h of bacteriophage R17 and 1.1 logs/h of feline leukemia virus (FeLV) in platelet concentrates maintained in standard storage bags. Platelet integrity and in vitro function before, immediately following photochemical treatment, and during prolonged storage after treatment, were evaluated by measuring: (1) extracellular pH; (2) platelet yields; (3) extracellular lactate dehydrogenase (LDH) levels; (4) platelet morphology; (5) platelet aggregation responsiveness; (6) thromboxane beta-2 (TXB-2) production; (7) dense body secretion; and (8) alpha granule secretion. These assays demonstrated that this photochemical inactivation system inactivated bacteria and viruses in platelet concentrates with minimal adverse effects on the in vitro function of platelets in comparison to untreated control concentrates maintained under current, standard blood bank conditions

  17. The Role of Photolabile Dermal Nitric Oxide Derivates in Ultraviolet Radiation (UVR-Induced Cell Death

    Directory of Open Access Journals (Sweden)

    Christoph V. Suschek

    2012-12-01

    Full Text Available Human skin is exposed to solar ultraviolet radiation comprising UVB (280–315 nm and UVA (315–400 nm on a daily basis. Within the last two decades, the molecular and cellular response to UVA/UVB and the possible effects on human health have been investigated extensively. It is generally accepted that the mutagenic and carcinogenic properties of UVB is due to the direct interaction with DNA. On the other hand, by interaction with non-DNA chromophores as endogenous photosensitizers, UVA induces formation of reactive oxygen species (ROS, which play a pivotal role as mediators of UVA-induced injuries in human skin. This review gives a short overview about relevant findings concerning the molecular mechanisms underlying UVA/UVB-induced cell death. Furthermore, we will highlight the potential role of cutaneous antioxidants and photolabile nitric oxide derivates (NODs in skin physiology. UVA-induced decomposition of the NODs, like nitrite, leads not only to non-enzymatic formation of nitric oxide (NO, but also to toxic reactive nitrogen species (RNS, like peroxynitrite. Whereas under antioxidative conditions the generation of protective amounts of NO is favored, under oxidative conditions, less injurious reactive nitrogen species are generated, which may enhance UVA-induced cell death.

  18. Short and Long Term Variation in Ultraviolet Radiation and Multiple Sclerosis

    Directory of Open Access Journals (Sweden)

    George E. Davis

    2012-02-01

    Full Text Available We examined the role of ultraviolet radiation (UVR in persons diagnosed with multiple sclerosis (MS in four different populations, Italians, Danish, White and African Americans. We tested whether variation in UVR as determined by seasons (short term variation and solar cycles (long term variation is related to MS birth month and to survival as measured by lifespan. Cases were selected from three Italian MS Case Registries (2,737; from the United States National Center for Health Statistics (56,020; and from the Danish Multiple Sclerosis registry (15,900. Chi-square tests were used to study the pattern of month of birth distribution in patients with MS comparing with general population data. T-tests were employed to study solar cycles association with lifespan. A surplus of births was observed in June for White Americans. A decrease of births in October and November, though not significant after multiple testing correction, was observed in the three populations. In White American with MS overall, males and females, we found that solar cycle is associated with lifespan. We found that season and solar cycles have some role in MS susceptibility and life duration. However, this is an exploratory analysis and further work is needed to discern the association.

  19. Avoidance of solar ultraviolet radiation by juvenile coho salmon (Oncorhynchus kisutch)

    International Nuclear Information System (INIS)

    Shade-seeking behavior and avoidance of solar ultraviolet radiation (UVR) by newly emerged coho salmon (Oncorhynchus kisutch) alevins and two-month-old coho juveniles was documented in experimental trials in the Little Qualicum River, British Columbia, using outdoor chambers that provided the fish with a binary choice of photo environments. Under high solar intensifies (i.e., midsummer, cloudless skies) coho of both age classes strongly preferred 50% neutral density shaded conditions to unattenuated full-spectrum (280-700 nm) sunlight (t test, p< 0.025). In addition, coho alevins and juveniles showed a high selective avoidance of UVR (280-400 nm) (t test, p<0.05). Within the UVR spectrum, coho responded significantly to UVA (320-400 nm) (t test, p=0.028). Evidence of UVB (280-320 nm) avoidance was confounded by higher visible and UVA irradiance levels under screens exposing coho to UVB. Under lower solar intensifies (i.e., cloudy skies) coho showed no spectral preference and did not seek neutral density shade. Behavioral avoidance of high intensity UVR, particularly UVA, suggests that shade-seeking behavior of juvenile coho may be linked to avoiding potentially harmful UVR exposure. (author)

  20. Solar ultraviolet radiation: properties, characteristics and amounts observed in Brazil and South America.

    Science.gov (United States)

    Corrêa, Marcelo de Paula

    2015-01-01

    The beneficial and harmful effects of human exposure to solar ultraviolet radiation (UV-R) are topics that arouse great interest not only among physicians and scientists, but also the general public and the media. Currently, discussions on vitamin D synthesis (beneficial effect) are confronted with the high and growing number of new cases of non-melanoma skin cancer and other diseases of the skin and eyes (harmful effect) diagnosed each year in Brazil. However, the lack of scientific knowledge on the UV-R in Brazil and South America leads to adoption of protective measures based on studies conducted in Europe and USA, where the amounts of UV-R available at surface and the sun-exposure habits and characteristics of the population are significantly different from those observed in Brazil. In order to circumvent this problem, the Brazilian Society of Dermatology recently published the Brazilian Consensus of Photoprotection based on recent studies performed locally. The main goal of this article is to provide detailed educational information on the main properties and characteristics of UV-R and UV index in a simple language. It also provides: a) a summary of UV-R measurements recently performed in Brazil; b) a comparison with those performed in Europe; and, c) an evaluation to further clarify the assessment of potential harm and health effects owing to chronic exposures. PMID:26131858

  1. Vacuum ultraviolet spectroscopy of molecules of environmental and astrophysical interest using synchrotron radiation

    International Nuclear Information System (INIS)

    Vacuum ultraviolet (VUV ∼6-25 eV) spectroscopy of polyatomic molecules is of considerable interest in many areas of physics, chemistry and biology. Its importance in the understanding of the various photochemical and photophysical processes in the atmosphere, astrophysical objects and biological systems etc. has been well recognized. VUV spectroscopic investigations in early days were often constrained by the limitations of traditional light sources which were either very weak or not continuously tunable. In the past few decades, synchrotron radiation has revolutionized VUV and soft X-ray spectroscopy, owing to its unique properties like high brilliance, continuous tenability, and well-defined pulsed time structure and polarization. India has two synchrotron sources, Indus-1 and lndus-2, at the Raja Ramanna Centre for Advanced Technology, Indore. In particular, the Indus-1 source, which is a 450 MeV storage ring with critical wavelength (λc) of 61 Å and a photon flux of 7 x 1011 photons/sec/mrad/0.1% bandwidth at λc, is ideally suited for VUV spectroscopy. In this talk we discuss our very recent work on the VUV spectroscopy of molecules, particularly of environmental and astrophysical interest. An overview of the experimental and theoretical issues involved in this work will be presented with a focus on new findings. (author)

  2. Is ultra-violet radiation the main force shaping molecular evolution of varicella-zoster virus?

    Directory of Open Access Journals (Sweden)

    Escobar-Gutiérrez Alejandro

    2011-07-01

    Full Text Available Abstract Background Varicella (chickenpox exhibits a characteristic epidemiological pattern which is associated with climate. In general, primary infections in tropical regions are comparatively less frequent among children than in temperate regions. This peculiarity regarding varicella-zoster virus (VZV infection among certain age groups in tropical regions results in increased susceptibility during adulthood in these regions. Moreover, this disease shows a cyclic behavior in which the number of cases increases significantly during winter and spring. This observation further supports the participation of environmental factors in global epidemiology of chickenpox. However, the underlying mechanisms responsible for this distinctive disease behavior are not understood completely. In a recent publication, Philip S. Rice has put forward an interesting hypothesis suggesting that ultra-violet (UV radiation is the major environmental factor driving the molecular evolution of VZV. Discussion While we welcomed the attempt to explain the mechanisms controlling VZV transmission and distribution, we argue that Rice's hypothesis takes lightly the circulation of the so called "temperate VZV genotypes" in tropical regions and, to certain degree, overlooks the predominance of such lineages in certain non-temperate areas. Here, we further discuss and present new information about the overwhelming dominance of temperate VZV genotypes in Mexico regardless of geographical location and climate. Summary UV radiation does not satisfactorily explain the distribution of VZV genotypes in different tropical and temperate regions of Mexico. Additionally, the cyclic behavior of varicella does not shown significant differences between regions with different climates in the country. More studies should be conducted to identify the factors directly involved in viral spreading. A better understanding of the modes of transmissions exploited by VZV and their effect on viral

  3. Tumor necrosis factor beta and ultraviolet radiation are potent regulators of human keratinocyte ICAM-1 expression

    International Nuclear Information System (INIS)

    Intercellular adhesion molecule-1 (ICAM-1) functions as a ligand of leukocyte function-associated antigen-1 (LFA-1), as well as a receptor for human picorna virus, and its regulation thus affects various immunologic and inflammatory reactions. The weak, constitutive ICAM-1 expression on human keratinocytes (KC) can be up-regulated by cytokines such as interferon-gamma (IFN gamma) and tumor necrosis factor alpha (TNF alpha). In order to further examine the regulation of KC ICAM-1 expression, normal human KC or epidermoid carcinoma cells (KB) were incubated with different cytokines and/or exposed to ultraviolet (UV) radiation. Subsequently, ICAM-1 expression was monitored cytofluorometrically using a monoclonal anti-ICAM-1 antibody. Stimulation of cells with recombinant human (rh) interleukin (IL) 1 alpha, rhIL-4, rhIL-5, rhIL-6, rh granulocyte/macrophage colony-stimulating factor (GM-CSF), rh interferon alpha (rhIFN alpha), and rh transforming growth factor beta (TGF beta) did not increase ICAM-1 surface expression. In contrast, rhTNF beta significantly up-regulated ICAM-1 expression in a time- and dose-dependent manner. Moreover, the combination of rhTNF beta with rhIFN gamma increased the percentage of ICAM-1-positive KC synergistically. This stimulatory effect of rhTNF beta was further confirmed by the demonstration that rhTNF beta was capable of markedly enhancing ICAM-1 mRNA expression in KC. Finally, exposure of KC in vitro to sublethal doses of UV radiation (0-100 J/m2) prior to cytokine (rhIFN tau, rhTNF alpha, rhTNF beta) stimulation inhibited ICAM-1 up-regulation in a dose-dependent fashion. These studies identify TNF beta and UV light as potent regulators of KC ICAM-1 expression, which may influence both attachment and detachment of leukocytes and possibly viruses to KC

  4. Degradation of microbial fluorescence biosignatures by solar ultraviolet radiation on Mars

    Science.gov (United States)

    Dartnell, Lewis R.; Patel, Manish R.

    2014-04-01

    Recent and proposed robotic missions to Mars are equipped with implements to expose or excavate fresh material from beneath the immediate surface. Once brought into the open, any organic molecules or potential biosignatures of present or past life will be exposed to the unfiltered solar ultraviolet (UV) radiation and face photolytic degradation over short time courses. The key question, then, is what is the window of opportunity for detection of recently exposed samples during robotic operations? Detection of autofluorescence has been proposed as a simple method for surveying or triaging samples for organic molecules. Using a Mars simulation chamber we conduct UV exposures on thin frozen layers of two model microorganisms, the radiation-resistant polyextremophile Deinococcus radiodurans and the cyanobacterium Synechocystis sp. PCC 6803. Excitation-emission matrices (EEMs) are generated of the full fluorescence response to quantify the change in signal of different cellular fluorophores over Martian equivalent time. Fluorescence of Deinococcus cells, protected by a high concentration of carotenoid pigments, was found to be relatively stable over 32 h of Martian UV irradiation, with around 90% of the initial signal remaining. By comparison, fluorescence from protein-bound tryptophan in Synechocystis is much more sensitive to UV photodegradation, declining to 50% after 64 h exposure. The signal most readily degraded by UV irradiation is fluorescence of the photosynthetic pigments - diminished to only 35% after 64 h. This sensitivity may be expected as the biological function of chlorophyll and phycocyanin is to optimize the harvesting of light energy and so they are readily photobleached. A significant increase in a ~450 nm emission feature is interpreted as accumulation of fluorescent cellular degradation products from photolysis. Accounting for diurnal variation in Martian sunlight, this study calculates that frozen cellular biosignatures would remain detectable by

  5. Impact of ultraviolet-B radiation on planktonic fish larvae: Alteration of the osmoregulatory function

    Energy Technology Data Exchange (ETDEWEB)

    Sucre, Elliott, E-mail: elliott.sucre@univ-montp2.fr [AEO Team (Adaptation Ecophysiologique et Ontogenese), UMR 5119 Ecosym UM2, CNRS, IRD, Ifremer, UM1, Universite Montpellier 2, cc092, Pl. Eugene Bataillon, 34095 Montpellier, Cx 05 (France); Vidussi, Francesca [RESEAUX Team (Reseaux Planctoniques et Changement Environnemental), UMR 5119 Ecosym UM2, CNRS, IRD, Ifremer, UM1, Universite Montpellier 2, cc093, Pl. Eugene Bataillon, 34095 Montpellier, Cx 05 (France); Mostajir, Behzad [RESEAUX Team (Reseaux Planctoniques et Changement Environnemental), UMR 5119 Ecosym UM2, CNRS, IRD, Ifremer, UM1, Universite Montpellier 2, cc093, Pl. Eugene Bataillon, 34095 Montpellier, Cx 05 (France); Centre d' ecologie marine experimentale MEDIMEER (Mediterranean centre for Marine Ecosystem Experimental Research), Universite Montpellier 2-CNRS (UMS 3301), Station Mediterraneenne de l' Environnement Littoral, MEDIMEER, 2 Rue des Chantiers, 34200 Sete (France); Charmantier, Guy; Lorin-Nebel, Catherine [AEO Team (Adaptation Ecophysiologique et Ontogenese), UMR 5119 Ecosym UM2, CNRS, IRD, Ifremer, UM1, Universite Montpellier 2, cc092, Pl. Eugene Bataillon, 34095 Montpellier, Cx 05 (France)

    2012-03-15

    Coastal marine ecosystems are submitted to variations of several abiotic and biotic parameters, some of them related to global change. Among them the ultraviolet-B (UV-B) radiation (UVBR: 280-320 nm) may strongly impact planktonic fish larvae. The consequences of an increase of UVBR on the osmoregulatory function of Dicentrarchus labrax larvae have been investigated in this study. In young larvae of D. labrax, as in other teleosts, osmoregulation depends on tegumentary ion transporting cells, or ionocytes, mainly located on the skin of the trunk and of the yolk sac. As early D. labrax larvae passively drift in the top water column, ionocytes are exposed to solar radiation. The effect of UVBR on larval osmoregulation in seawater was evaluated through nanoosmometric measurements of the blood osmolality after exposure to different UV-B treatments. A loss of osmoregulatory capability occured in larvae after 2 days of low (50 {mu}W cm{sup -2}: 4 h L/20 h D) and medium (80 {mu}W cm{sup -2}: 4 h L/20 h D) UVBR exposure. Compared to control larvae kept in the darkness, a significant increase in blood osmolality, abnormal behavior and high mortalities were detected in larvae exposed to UVBR from 2 days on. At the cellular level, an important decrease in abundance of tegumentary ionocytes and mucous cells was observed after 2 days of exposure to UVBR. In the ionocytes, two major osmoeffectors were immunolocalized, the Na{sup +}/K{sup +}-ATPase and the Na{sup +}/K{sup +}/2Cl{sup -} cotransporter. Compared to controls, the fluorescent immunostaining was lower in UVBR-exposed larvae. We hypothesize that the impaired osmoregulation in UVBR-exposed larvae originates from the lower number of tegumentary ionocytes and mucous cells. This alteration of the osmoregulatory function could negatively impact the survival of young larvae at the surface water exposed to UVBR.

  6. Impact of ultraviolet-B radiation on planktonic fish larvae: Alteration of the osmoregulatory function

    International Nuclear Information System (INIS)

    Coastal marine ecosystems are submitted to variations of several abiotic and biotic parameters, some of them related to global change. Among them the ultraviolet-B (UV-B) radiation (UVBR: 280–320 nm) may strongly impact planktonic fish larvae. The consequences of an increase of UVBR on the osmoregulatory function of Dicentrarchus labrax larvae have been investigated in this study. In young larvae of D. labrax, as in other teleosts, osmoregulation depends on tegumentary ion transporting cells, or ionocytes, mainly located on the skin of the trunk and of the yolk sac. As early D. labrax larvae passively drift in the top water column, ionocytes are exposed to solar radiation. The effect of UVBR on larval osmoregulation in seawater was evaluated through nanoosmometric measurements of the blood osmolality after exposure to different UV-B treatments. A loss of osmoregulatory capability occured in larvae after 2 days of low (50 μW cm−2: 4 h L/20 h D) and medium (80 μW cm−2: 4 h L/20 h D) UVBR exposure. Compared to control larvae kept in the darkness, a significant increase in blood osmolality, abnormal behavior and high mortalities were detected in larvae exposed to UVBR from 2 days on. At the cellular level, an important decrease in abundance of tegumentary ionocytes and mucous cells was observed after 2 days of exposure to UVBR. In the ionocytes, two major osmoeffectors were immunolocalized, the Na+/K+-ATPase and the Na+/K+/2Cl− cotransporter. Compared to controls, the fluorescent immunostaining was lower in UVBR-exposed larvae. We hypothesize that the impaired osmoregulation in UVBR-exposed larvae originates from the lower number of tegumentary ionocytes and mucous cells. This alteration of the osmoregulatory function could negatively impact the survival of young larvae at the surface water exposed to UVBR.

  7. Supervised artificial neural network-based method for conversion of solar radiation data (case study: Algeria)

    Science.gov (United States)

    Laidi, Maamar; Hanini, Salah; Rezrazi, Ahmed; Yaiche, Mohamed Redha; El Hadj, Abdallah Abdallah; Chellali, Farouk

    2016-01-01

    In this study, a backpropagation artificial neural network (BP-ANN) model is used as an alternative approach to predict solar radiation on tilted surfaces (SRT) using a number of variables involved in physical process. These variables are namely the latitude of the site, mean temperature and relative humidity, Linke turbidity factor and Angstrom coefficient, extraterrestrial solar radiation, solar radiation data measured on horizontal surfaces (SRH), and solar zenith angle. Experimental solar radiation data from 13 stations spread all over Algeria around the year (2004) were used for training/validation and testing the artificial neural networks (ANNs), and one station was used to make the interpolation of the designed ANN. The ANN model was trained, validated, and tested using 60, 20, and 20 % of all data, respectively. The configuration 8-35-1 (8 inputs, 35 hidden, and 1 output neurons) presented an excellent agreement between the prediction and the experimental data during the test stage with determination coefficient of 0.99 and root meat squared error of 5.75 Wh/m2, considering a three-layer feedforward backpropagation neural network with Levenberg-Marquardt training algorithm, a hyperbolic tangent sigmoid and linear transfer function at the hidden and the output layer, respectively. This novel model could be used by researchers or scientists to design high-efficiency solar devices that are usually tilted at an optimum angle to increase the solar incident on the surface.

  8. Active Path Selection of Fluid Microcapsules in Artificial Blood Vessel by Acoustic Radiation Force

    Science.gov (United States)

    Masuda, Kohji; Muramatsu, Yusuke; Ueda, Sawami; Nakamoto, Ryusuke; Nakayashiki, Yusuke; Ishihara, Ken

    2009-07-01

    Micrometer-sized microcapsules collapse upon exposure to ultrasound. Use of this phenomenon for a drug delivery system (DDS), not only for local delivery of medication but also for gene therapy, should be possible. However, enhancing the efficiency of medication is limited because capsules in suspension diffuse in the human body after injection, since the motion of capsules in blood flow cannot be controlled. To control the behavior of microcapsules, acoustic radiation force was introduced. We detected local changes in microcapsule density by producing acoustic radiation force in an artificial blood vessel. Furthermore, we theoretically estimated the conditions required for active path selection of capsules at a bifurcation point in the artificial blood vessel. We observed the difference in capsule density at both in the bifurcation point and in alternative paths downstream of the bifurcation point for different acoustic radiation forces. Comparing the experimental results with those obtained theoretically, the conditions for active path selection were calculated from the acoustic radiation force and fluid resistance of the capsules. The possibility of controlling capsule flow towards a specific point in a blood vessel was demonstrated.

  9. Primordial Star Formation under the Influence of Far Ultraviolet Radiation: 1540 Cosmological Halos and the Stellar Mass Distribution

    OpenAIRE

    Hirano, Shingo; Hosokawa, Takashi; Yoshida, Naoki; Omukai, Kazuyuki; Yorke, Harold W.

    2015-01-01

    We perform a large set of cosmological simulations of early structure formation and follow the formation and evolution of 1540 star-forming gas clouds to derive the mass distribution of primordial stars. The star formation in our cosmological simulations is characterized by two distinct populations, the so-called Population III.1 stars and primordial stars formed under the influence of far ultraviolet (FUV) radiation (Population III.2D stars). In this work, we determine the stellar masses by ...

  10. A randomized controlled trial of green tea catechins in protection against ultraviolet radiation-induced cutaneous inflammation.

    OpenAIRE

    Farrar, Mark D; Nicolaou, Anna; Clarke, Kayleigh A; Mason, Sarah,; Massey, Karen A.; Dew, Tristan P; Watson, Rachel EB; Williamson, Gary; Rhodes, Lesley E; Farrar MD, Nicolaou A, Clarke KA, Mason S, Massey KA, Dew TP, Watson REB, Williamson G, Rhodes LE

    2015-01-01

    BACKGROUND: Safe systemic protection from the health hazards of ultraviolet radiation (UVR) in sunlight is desirable. Green tea is consumed globally and is reported to have anti-inflammatory properties, which may be mediated through the impact on cyclooxygenase and lipoxygenase pathways. Recent data suggest that green tea catechins (GTCs) reduce acute UVR effects, but human trials examining their photoprotective potential are scarce. OBJECTIVE: We performed a double-blind, randomized, placebo...

  11. Impact of plasma jet vacuum ultraviolet radiation on reactive oxygen species generation in bio-relevant liquids

    International Nuclear Information System (INIS)

    Plasma medicine utilizes the combined interaction of plasma produced reactive components. These are reactive atoms, molecules, ions, metastable species, and radiation. Here, ultraviolet (UV, 100–400 nm) and, in particular, vacuum ultraviolet (VUV, 10–200 nm) radiation generated by an atmospheric pressure argon plasma jet were investigated regarding plasma emission, absorption in a humidified atmosphere and in solutions relevant for plasma medicine. The energy absorption was obtained for simple solutions like distilled water (dH2O) or ultrapure water and sodium chloride (NaCl) solution as well as for more complex ones, for example, Rosewell Park Memorial Institute (RPMI 1640) cell culture media. As moderate stable reactive oxygen species, hydrogen peroxide (H2O2) was studied. Highly reactive oxygen radicals, namely, superoxide anion (O2•−) and hydroxyl radicals (•OH), were investigated by the use of electron paramagnetic resonance spectroscopy. All species amounts were detected for three different treatment cases: Plasma jet generated VUV and UV radiation, plasma jet generated UV radiation without VUV part, and complete plasma jet including all reactive components additionally to VUV and UV radiation. It was found that a considerable amount of radicals are generated by the plasma generated photoemission. From the experiments, estimation on the low hazard potential of plasma generated VUV radiation is discussed

  12. Wearable device for monitoring momentary presence of intense x-ray and/or ultra-violet radiations

    International Nuclear Information System (INIS)

    A credit-card-size clear-plastic-encased device can be worn or carried by a person to warn him of the momentary presence of dangerous intensities of ultra-violet and/or x-ray radiations. A base lamina (e.g. of cardboard) is coated with a material (e.g. zinc-cadmium sulfide or lead-barium sulfate) which fluoresces under such radiations. Numerals, letters, words or symbols are printed over the fluorescent coat with a material inhibitory to said radiations so that a warning message in dark print will appear on a light background when dangerous intensities of said radiations are present. An x-ray-warning area is covered with an ultra-violet absorbing screen so that said area will glow only under x-rays (Which rays will also activate the remaining ultra-violet-responsive area). The colors of the laminas and the coats are so selected that the messages are not visible when dangerous radiations are not present. If desired, only the message can be printed with fluorescent material so as to glow on a darker background. Optionally, step-layer attenuation devices can be added to indicate degrees of radiation; and reflecting surfaces can underlie the fluorescent coat to increase efficiency and/or sensitively

  13. Impact of plasma jet vacuum ultraviolet radiation on reactive oxygen species generation in bio-relevant liquids

    Energy Technology Data Exchange (ETDEWEB)

    Jablonowski, H.; Hammer, M. U.; Reuter, S. [Center for Innovation Competence plasmatis, Felix-Hausdorff-Str. 2, 17489 Greifswald (Germany); Leibniz Institute for Plasma Science and Technology, INP Greifswald e.V. Felix-Hausdorff-Str. 2, 17489 Greifswald (Germany); Bussiahn, R.; Weltmann, K.-D.; Woedtke, Th. von [Leibniz Institute for Plasma Science and Technology, INP Greifswald e.V. Felix-Hausdorff-Str. 2, 17489 Greifswald (Germany)

    2015-12-15

    Plasma medicine utilizes the combined interaction of plasma produced reactive components. These are reactive atoms, molecules, ions, metastable species, and radiation. Here, ultraviolet (UV, 100–400 nm) and, in particular, vacuum ultraviolet (VUV, 10–200 nm) radiation generated by an atmospheric pressure argon plasma jet were investigated regarding plasma emission, absorption in a humidified atmosphere and in solutions relevant for plasma medicine. The energy absorption was obtained for simple solutions like distilled water (dH{sub 2}O) or ultrapure water and sodium chloride (NaCl) solution as well as for more complex ones, for example, Rosewell Park Memorial Institute (RPMI 1640) cell culture media. As moderate stable reactive oxygen species, hydrogen peroxide (H{sub 2}O{sub 2}) was studied. Highly reactive oxygen radicals, namely, superoxide anion (O{sub 2}{sup •−}) and hydroxyl radicals ({sup •}OH), were investigated by the use of electron paramagnetic resonance spectroscopy. All species amounts were detected for three different treatment cases: Plasma jet generated VUV and UV radiation, plasma jet generated UV radiation without VUV part, and complete plasma jet including all reactive components additionally to VUV and UV radiation. It was found that a considerable amount of radicals are generated by the plasma generated photoemission. From the experiments, estimation on the low hazard potential of plasma generated VUV radiation is discussed.

  14. Impact of plasma jet vacuum ultraviolet radiation on reactive oxygen species generation in bio-relevant liquids

    Science.gov (United States)

    Jablonowski, H.; Bussiahn, R.; Hammer, M. U.; Weltmann, K.-D.; von Woedtke, Th.; Reuter, S.

    2015-12-01

    Plasma medicine utilizes the combined interaction of plasma produced reactive components. These are reactive atoms, molecules, ions, metastable species, and radiation. Here, ultraviolet (UV, 100-400 nm) and, in particular, vacuum ultraviolet (VUV, 10-200 nm) radiation generated by an atmospheric pressure argon plasma jet were investigated regarding plasma emission, absorption in a humidified atmosphere and in solutions relevant for plasma medicine. The energy absorption was obtained for simple solutions like distilled water (dH2O) or ultrapure water and sodium chloride (NaCl) solution as well as for more complex ones, for example, Rosewell Park Memorial Institute (RPMI 1640) cell culture media. As moderate stable reactive oxygen species, hydrogen peroxide (H2O2) was studied. Highly reactive oxygen radicals, namely, superoxide anion (O2•-) and hydroxyl radicals (•OH), were investigated by the use of electron paramagnetic resonance spectroscopy. All species amounts were detected for three different treatment cases: Plasma jet generated VUV and UV radiation, plasma jet generated UV radiation without VUV part, and complete plasma jet including all reactive components additionally to VUV and UV radiation. It was found that a considerable amount of radicals are generated by the plasma generated photoemission. From the experiments, estimation on the low hazard potential of plasma generated VUV radiation is discussed.

  15. Effects of long-term, elevated ultraviolet-B radiation on phytochemicals in the bark of silver birch (Betula pendula).

    Science.gov (United States)

    Tegelberg, Riitta; Aphalo, Pedro J; Julkunen-Tiitto, Riitta

    2002-12-01

    Long-term outdoor experiments were conducted to investigate the effects of elevated ultraviolet-B (UV-B, 280-320 nm) radiation on secondary metabolites (phenolics and terpenoids) and the main soluble sugars (sucrose, raffinose and glucose) in the bark of silver birch (Betula pendula Roth) saplings. Saplings were exposed to a constant 50% increase in erythemal UV irradiance (UV-B(CIE); based on the CIE (International Commission on Illumination) erythemal action spectrum) and a small increase in UV-A radiation (320-400 nm) for three growing seasons in an irradiation field in central Finland. Two control groups were used: saplings exposed to ambient radiation and saplings exposed to slightly increased UV-A radiation. Concentrations of sucrose, raffinose and glucose in bark were higher in UV-treated saplings than in saplings grown in ambient radiation, indicating that stem carbohydrate metabolism was changed by long-term elevated UV radiation. Saplings in the elevated UV-A + UV-B radiation treatment and the UV-A radiation control treatment had significantly increased concentrations of certain UV-absorbing phenolics, such as salidroside, 3,4'-dihydroxypropiophenone-3-glucoside, (+)-catechin and (-)-epicatechin compared with saplings in ambient radiation. In contrast, the radiation treatments had no effect on the non-UV-B-absorbing terpenoids, papyriferic acid and deacetylpapyriferic acid. We conclude that plant parts, in addition to leaves, accumulate specific phenolic UV-filters in response to UV radiation exposure. PMID:12464579

  16. Target and Non-target metabolomics profiling of different barley varieties affected by enhanced ultraviolet radiation and various C:N stoichiometry

    Czech Academy of Sciences Publication Activity Database

    Oravec, Michal; Novotná, Kateřina; Rajsnerová, P.; Veselá, B.; Urban, Otmar; Holub, Petr; Klem, Karel

    2015-01-01

    Roč. 29, č. 1 (2015), s. 887.7. ISSN 0892-6638 Institutional support: RVO:67179843 Keywords : metabolomic profiling * different barley varieties * ultraviolet radiation Subject RIV: EH - Ecology, Behaviour

  17. Effect of gamma and ultraviolet radiations in isolates of Metarhizium anisopliae (METSCH) Sorokin, 1883 and its utilization aiming Diatraea saccharalis (FABRICIUS, 1794) control

    International Nuclear Information System (INIS)

    The effects of gamma radiation and ultraviolet in isolated of the fungus Metarhizium anisopliae (Metsch) Sorokin, and the utilization of this pathogen for the Diatrae saccharalis (Fabr.) control are studied. (L.M.J.)

  18. Entropy-based artificial viscosity stabilization for non-equilibrium Grey Radiation-Hydrodynamics

    International Nuclear Information System (INIS)

    The entropy viscosity method is extended to the non-equilibrium Grey Radiation-Hydrodynamic equations. The method employs a viscous regularization to stabilize the numerical solution. The artificial viscosity coefficient is modulated by the entropy production and peaks at shock locations. The added dissipative terms are consistent with the entropy minimum principle. A new functional form of the entropy residual, suitable for the Radiation-Hydrodynamic equations, is derived. We demonstrate that the viscous regularization preserves the equilibrium diffusion limit. The equations are discretized with a standard Continuous Galerkin Finite Element Method and a fully implicit temporal integrator within the MOOSE multiphysics framework. The method of manufactured solutions is employed to demonstrate second-order accuracy in both the equilibrium diffusion and streaming limits. Several typical 1-D radiation-hydrodynamic test cases with shocks (from Mach 1.05 to Mach 50) are presented to establish the ability of the technique to capture and resolve shocks

  19. Validation of ultraviolet radiation budgets using satellite observations from the OMI instrument

    International Nuclear Information System (INIS)

    Satellite retrieval of ozone, clouds, aerosols and ground albedo allows the modelling of ultraviolet (UV)-doses received at the ground. UV-doses derived from satellite observations are highly useful in analyzing regional differences in the effects of ozone depletion and climate change on the biologically effective UV-radiation levels. RIVM has developed and used UV-mapping and UV-risk mapping techniques in environmental assessments in evaluating the effects of ozone depletion and climate change. This project provides a validation study on the OMUVB product by means of a comparison with ground-based measurements. This validation should demonstrate if the OMUVB product can be used from the perspective of long-term environmental trend assessments. Comparing ground-based UV-measurements with the OMUVB product, we show that the product consistently overestimates the UV-doses received at the ground in Europe. The systematic comparison with data from 8 European sites shows on average a 15% overestimate in the yearly integrated UV with a site-to-site variability of around 8%. For four of the more northern sites the overestimation in yearly doses is between 5-10%, and for the four sites that are more southern the deviation is 20-27%. Using the ozone and reflectivity data from the OMI-instrument (Ozone Monitoring Instrument) in combination with the AMOUR-algorithm (Assessment Model for Ultraviolet radiation and Risks) shows smaller overestimates of on average 5-6% with a similar variability between the sites. The variability between sites is largely caused by aerosol and albedo effects and is reduced to 3% if local data on aerosol and albedo are used. The overestimates in the OMUVB product are primarily due to too low (tropospheric) aerosol loads used for the European sites. In addition, our comparison shows that under heavy clouded conditions the cloud modification factors are too high. This contributes to the overall too high UV-doses of the OMUVB product. Environmental

  20. Combined effects of copper and ultraviolet radiation on a microscopic green alga in natural soft lake waters of varying dissolved organic carbon content

    International Nuclear Information System (INIS)

    Selenastrum capricornutum was grown in two lake waters of differing dissolved organic carbon content (1.8 vs. 9.1 mg DOC l-1) to determine the responses of population dynamics and photosynthesis to Cu, and to assess the modifying effects of varying ultraviolet radiation (UVR) exposure. In the absence of UVR, the mean EC50 for Cu effect on population growth rate was 2.3-2.6 μg l-1 in the low DOC water and 17.4-26.2 μg l-1 in the high DOC water. The variable chlorophyll a fluorescence ratio, Fv/Fm, decreased approximately in parallel with the diminished growth rates. Exposure of the higher DOC lake water to full spectrum artificial radiation caused an increase of Cu2+ concentration, compared to samples held in darkness or in photosynthetically active radiation (PAR) only. Full spectrum exposures also resulted in a lower (although not significantly so) EC50 for Cu effect on growth rate, consistent with response to the moderately elevated Cu2+ concentration. Cu2+ concentration was unaffected by radiation exposure in the low DOC water, and EC50s for growth were also unaffected except in the most severe UVR treatment, which was >40% inhibited even in the absence of added Cu. Using Fv/Fm as an end-point, there was no evidence of interactions between UVR and Cu under the relatively low PAR exposures used here. Algal growth and photosynthesis was extremely sensitive to Cu in these soft lake waters, with EC50s close to current water quality standards in the low DOC water

  1. MDS G(N) fast differentiation between natural and artificial gamma radiation with a new class of mobile instruments

    International Nuclear Information System (INIS)

    A State-of-the-Art tool used for detecting and tracking artificial gamma radiation out of a helicopter or a vehicle is the MDS G(N) - Mobile Detection System. A highly sensitive scintillation detector detects a significant artificial gamma radiation on the ground even if the helicopter is travelling at high speed. The GPS-aided system visualizes the measured values on a moveable map displayed on the screen of a notebook every second. The colours of the continuously entered points do represent adjustable alarm thresholds. This way, location and intensity of an unknown radioactive source or a radioactive contamination can be determined very quickly. The NBR-technology (Natural Background Rejection) which is used here leads to expressive measurement results differentiating between artificial and natural gamma radiation. Additional He-3 detectors allow simultaneously the detection of neutrons. The NBR principle - developed by Thermo Scientific - stands out for its very short response times. Thus, artificial radiation can be detected reliably within seconds - even when the unit is operated by untrained staff. Unlike traditional analytic measuring techniques, the NBR method is able to detect artificial radiation sources hidden or strongly shielded gamma sources clearly from the natural background radiation. The measuring range from 1 nSv/h to 20 ?Sv/h and is extended to 1 Sv/h with a Geiger Mueller counting tube. The sensitivity amounts to max. 20000 cps (referred to 1 ?Sv/h for Cs-137). The NBR- technique is well-proven and tested for: tracking hidden radiation sources, even such ones with low activity or which are shielded, detection of artificial radiation portions in the range of the natural background, reliably measuring the ambient equivalent dose rate in the range of the natural background, fast detection of artificial radioactivity out of helicopters and vehicles.(author)

  2. Differential responses of growth and photosynthesis in Cyamopsis tetragonoloba grown under ultraviolet-B and supplemental long-wavelength radiations

    International Nuclear Information System (INIS)

    Cyamopsis tetragonoloba seedlings were subjected to continuous ultraviolet (UV)B radiation for 18 h and post-irradiated with 'white light' (WL) and UV-A enhanced fluorescent radiations. UV-B treatment alone reduced plant growth, pigment content, and photosynthetic activities. Supplementation of UV-A promoted the overall seedling growth and enhanced the synthesis of chlorophyll and carotenoids with a relatively high photosystem 1 activity. Post UV-B irradiation under WL failed to photoreactivate the LTV-B damage whereas a positive photoregulatory effect of UV-A was noticed in electron transport rates and low temperature fluorescence emission spectra

  3. Synergistic cytotoxicity and DNA strand breaks in cells and plasmid DNA exposed to uranyl acetate and ultraviolet radiation

    OpenAIRE

    Wilson, Janice; Zuniga, Mary C.; Yazzie, Filbert; Stearns, Diane M.

    2014-01-01

    Depleted uranium (DU) has a chemical toxicity that is independent of its radioactivity. The purpose of this study was to explore the photoactivation of uranyl ion by ultraviolet (UV) radiation as a chemical mechanism of uranium genotoxicity. The ability of UVB (302 nm) and UVA (368 nm) radiation to photoactivate uranyl ion to produce single strand breaks was measured in pBR322 plasmid DNA, and the presence of adducts and apurinic/apyrimidinic sites that could be converted to single strand bre...

  4. Spatio-temporal coherence of free-electron laser radiation in the extreme ultraviolet determined by a Michelson interferometer

    International Nuclear Information System (INIS)

    A key feature of extreme ultraviolet (XUV) radiation from free-electron lasers (FELs) is its spatial and temporal coherence. We measured the spatio-temporal coherence properties of monochromatized FEL pulses at 13.5 nm using a Michelson interferometer. A temporal coherence time of (59±8) fs has been determined, which is in good agreement with the spectral bandwidth given by the monochromator. Moreover, the spatial coherence in vertical direction amounts to about 15% of the beam diameter and about 12% in horizontal direction. The feasibility of measuring spatio-temporal coherence properties of XUV FEL radiation using interferometric techniques advances machine operation and experimental studies significantly.

  5. Two mire species respond differently to enhanced ultraviolet-B radiation: effects on biomass allocation and root exudation

    DEFF Research Database (Denmark)

    Rinnan, Riikka Tiivi Mariisa; Gehrke, Carola; Michelsen, Anders

    2006-01-01

    •  Increased ultraviolet-B (UV-B) radiation arising from stratospheric ozone depletion may influence soil microbial communities via effects on plant carbon allocation and root exudation. •  Eriophorum angustifolium and Narthecium ossifragum plants, grown in peatland mesocosms consisting of Sphagnum...... peat, peat pore water and natural microbial communities, were exposed outdoors to enhanced UV-B radiation simulating 15% ozone depletion in southern Scandinavia for 8 wk. •  Enhanced UV-B increased rhizome biomass and tended to decrease the biomass of the largest root fraction of N...

  6. Effects of ultraviolet radiation on microtubule organisation and morphogenesis in plants

    International Nuclear Information System (INIS)

    The involvement of the cytoskeleton in the development of somatic embryos was studied in Larix x eurolepis. Protoplasts were isolated from both somatic embryo-regenerating and non-generating cultures and fractionated on a discontinuous Percoll density gradient, whereby a highly embryogenic protoplast fraction could be enriched. Protoplasts of two cell lines of Larix eurolepis, one with regenerating potential and one lacking this potential, were compared. In contrast to the non-regenerating line were a protoplast-like organisation of the cortical microtubules was maintained, re-organisation of this microtubular network occurred in the regenerable line after only three days of culture, indicating that organised growth was occurring. However, this early organisation of cortical microtubules may not always be a valid marker for regenerable and non-regenerable material. In order to investigate the effect of ultraviolet-B (UV-B, 280-320 nm) radiation on the microtubule cytoskeleton, protoplasts were isolated from leaves of Petunia hybrida and subjected to four different doses of UV-B radiation. The organisation of the microtubules and the progression of the cells through the cell cycle was observed at 0, 24, 48 and 72 h after irradiation. UV-B induced breaks in the cortical microtubules resulting in shorter fragments with increasing amounts of radiation. Also, the division of the protoplasts was delayed, which was related to the absence of an microtubule network. Whole Petunia plants were grown in growth chambers in the presence and absence of UV-B. The plants responded to UV-B with increased rates of CO2 assimilation, a 60% increase in UV-screening compounds and the changes in the morphology of the leaves that were reflected in a 70-100% increase in leaf area and 20% decrease in leaf thickness. The microtubules of the epidermal cells was not affected by UV-B, nor was the number of epidermal cells (per unit area). The increase in leaf area in the UV-treated plants

  7. Analysis of ultraviolet radiation in Central China from observation and estimation

    International Nuclear Information System (INIS)

    Measurements of UV (ultraviolet) and global solar radiation in Central China during 2006–2012 were first reported to investigate the UV radiation variability in different time scales and its UV fraction under different sky conditions. Both UV irradiation and UV fraction showed similar features that peaked in values at noon during summer (July) and reached their lowest in winter (January) with annual mean values being about 0.49 MJ m−2 d−1 and 4.35%, respectively. It was also discovered that there were inverse relationships between UV fractions and clearness indexes at all sky conditions; clouds, water vapor and seasonality were main factors causing the daily variations of UV irradiations. The maximum UV irradiances decreased by 51.14% (33.49%) in overcast days when compared to clear days in summer (winter). By analyzing the dependence of UV irradiances on cosine of solar zenith angle and clearness index, an efficient all-sky model has been developed for estimating UV values in Central China, which has also been tested at Sanjiang and Lhasa and produced satisfied estimations. UV dataset from 1961 to 2011 in Central China was then reconstructed and annual mean daily UV irradiation was about 0.488 MJ m−2 d−1. There was a significant decreasing trend (−0.018 MJ m−2 d−1 per decade) during the last 50 years, the decreases were sharpest in summer (−0.027 MJ m−2 d−1 per decade) with smallest decreases being observed in autumn (−0.001 MJ m−2 d−1 per decade). Meanwhile, it was also revealed that UV energy began to increase since 1990s (0.003 MJ m−2 d−1 per year). - Highlights: • 7-Year measurements were used to show the temporal variability of UV and UV/G. • Characteristics of UV and UV/G under different sky conditions were investigated. • Dependence of UV on clearness index was studied in model development. • New all-sky model produced good estimates of UV energy at two other sites. • Long-term changes of UV radiation from 1961 to

  8. Effects of ultraviolet radiation on microtubule organisation and morphogenesis in plants

    Energy Technology Data Exchange (ETDEWEB)

    Staxen, I.

    1994-09-01

    The involvement of the cytoskeleton in the development of somatic embryos was studied in Larix x eurolepis. Protoplasts were isolated from both somatic embryo-regenerating and non-generating cultures and fractionated on a discontinuous Percoll density gradient. Protoplasts of two cell lines of Larix eurolepis, one with regenerating potential and one lacking this potential, were compared. In contrast to the non-regenerating line were a protoplast-like organisation of the cortical microtubules was maintained, re-organisation of this microtubular network occurred in the regenerable line after only three days of culture, indicating that organised growth was occurring. However, this early organisation of cortical microtubules may not always be a valid marker for regenerable and non-regenerable material. In order to investigate the effect of ultraviolet-B (UV-B, 280-320 nm) radiation on the microtubule cytoskeleton, protoplasts were isolated from leaves of Petunia hybrida and subjected to four different doses of UV-B radiation. The organisation of the microtubules and the progression of the cells through the cell cycle was observed at 0, 24, 48 and 72 h after irradiation. UV-B induced breaks in the cortical microtubules resulting in shorter fragments with increasing amounts of radiation. Also, the division of the protoplasts was delayed. Whole Petunia plants were grown in growth chambers in the presence and absence of UV-B. The plants responded to UV-B with increased rates of CO{sub 2} assimilation, a 60% increase in UV-screening compounds and the changes in the morphology of the leaves that were reflected in a 70-100% increase in leaf area and 20% decrease in leaf thickness. The microtubules of the epidermal cells was not affected by UV-B, nor was the number of epidermal cells (per unit area). The increase in leaf area in the UV-treated plants appeared due to stimulation of cell division in the leaf meristems. 111 refs, 5 figs, 2 tabs.

  9. Effects of ultraviolet radiation on the type-I collagen protein triple helical structure: A method for measuring structural changes through optical activity

    International Nuclear Information System (INIS)

    A detailed study of the effects of ultraviolet radiation on type-I collagen has been conducted. We have confirmed that exposure to ultraviolet radiation lowers the denaturation temperature of type-I collagen and that the triple helical state is destroyed provided that the radiation dose exceeds a threshold level, which is defined as the incident radiation dose that raises the sample temperature above the (lower) denaturation temperature. For incident radiation doses below threshold, the collagen molecule remains in a triple helical state. Denaturation is determined by changes in the optical activity of the collagen solution. Furthermore, a new instrument has been developed and tested to measure the optical rotatory dispersion properties of chiral molecules. The advantage of this instrument is that it enables a real-time measurement of the optical activity of chiral macromolecules while exposing samples to ultraviolet radiation and requiring no special sample preparation techniques. Using a differential measurement scheme, system errors have been minimized

  10. Vulnerability and behavioral response to ultraviolet radiation in the components of a foliar mite prey-predator system

    Science.gov (United States)

    Tachi, Fuyuki; Osakabe, Masahiro

    2012-12-01

    Ambient ultraviolet-B (UVB) radiation impacts plant-dwelling arthropods including herbivorous and predatory mites. However, the effects of UVB on prey-predator systems, such as that between the herbivorous spider mite and predatory phytoseiid mite, are poorly understood. A comparative study was conducted to determine the vulnerability and behavioral responses of these mites to ultraviolet (UV) radiation. First, we analyzed dose-response (cumulative irradiance-mortality) curves for the eggs of phytoseiid mites ( Neoseiulus californicus, Neoseiulus womersleyi, and Phytoseiulus persimilis) and the spider mite ( Tetranychus urticae) to UVB radiation from a UV lamp. This indicated that the phytoseiid mites were more vulnerable than the spider mite, although P. persimilis was slightly more tolerant than the other two phytoseiid mites. Second, we compared the avoidance behavior of adult female N. californicus and two spider mite species ( T. urticae, a lower leaf surface user; Panonychus citri, an upper leaf surface user) in response to solar UV and visible light. N. californicus actively avoided both types of radiation, whereas P. citri showed only minimal avoidance behavior. T. urticae actively avoided UV as well as N. californicus but exhibited a slow response to visible light as well as P. citri. Such variation in vulnerability and avoidance behavior accounts for differences in the species adaptations to solar UVB radiation. This may be the primary factor determining habitat use among these mites on host plant leaves, subsequently affecting accessibility by predators and also intraguild competition.

  11. A new absolute extreme ultraviolet image system designed for studying the radiated power of the Joint Texas Experimental Tokamak discharges

    International Nuclear Information System (INIS)

    A bolometer imaging system mounted on different toroidal and poloidal locations used for radiation observation has been developed in the Joint Texas Experimental Tokamak (J-TEXT tokamak). Three miniature pinhole AXUV16ELG (16 elements absolute extreme ultraviolet silicon photodiodes) array cameras, which are settled down in the same toroidal position but in three different poloidal places, can provide a broad viewing angle that covers the whole plasma cross-section, and hence can measure the total radiated power and provide the radiated emissive profile, while nine AXUV10EL (10 elements absolute extreme ultraviolet silicon photodiodes) array cameras are divided into three groups and will be mounted on different toroidal locations to observe the toroidal radiated power distribution. Among these detectors, one element of the AXUV16ELG array is absolutely calibrated by the synchrotron radiation source to verify the system reliability. Although there are some discrepancies between the typical responsivity given by IRD Co. and the calibrated results, it is confirmed that the discrepancies have no major effect on the final result after the simulation. The details of the system as well as observations are presented in the paper.

  12. INFLUENCE OF ULTRAVIOLET RADIATION ON MICROBIOLOGICAL AND SENSORY CHARACTERISTICS OF CERTAIN CATEGORIES OF VEGETABLES PRODUCTS AND THEIR PRESERVATION LIFE

    Directory of Open Access Journals (Sweden)

    Danilevici Constantin

    2010-01-01

    Full Text Available Research paper aims to highlight the scientific correlation between the influence of ultraviolet radiation (UV onsensory and microbiological characteristics of plant products in the category of leaves (lettuce and other types ofvegetables or fruit (bananas and their preservation’s duration, through their UV irradiation under certain conditions.The literature indicates a germicidal action of UV (medium UV on micro-organisms, optimal for λ = 254 nm. Theeffectiveness of radiation is influenced by duration of irradiation, the distance between the radiation source and thesample product and radiant power source.The action of microbial cell inactivation or destruction can be explained by changes in cellular structure andpermeability with changes at the level of mitochondria and the genetic material as a result of photochemical effects ofUV products. Research highlights the preservative effect of UV radiation (with λ = 254 nm and also their influence onsensory properties and positive to negative for leafy vegetables and fruits (bananas in our case.

  13. Total ozone and solar ultraviolet radiation, as derived from satellite and ground-based instrumentation at Dundee, Scotland

    International Nuclear Information System (INIS)

    Daily ozone measurements from satellite sensor data (Total Ozone Mapping Spectrometer-TOMS) over Dundee, Scotland (56.5° N, 3° W) during 1986±1992 with daily broad-band measurements of solar ultraviolet (UV) radiation reaching the ground deduced from ground-based instrumentation were used to investigate their correlation. The erythemally active UV radiation showed an increase of 35% during 1986±1992 while the total ozone amount showed a decrease of 10% during the same period. Furthermore, the ratio of the increase of UV radiation to the decrease in ozone concentration was maximum in July, showing that a small percentage decrease in total ozone during summer leads to a large percentage increase in solar UV radiation reaching the ground. (author)

  14. Studies of ionising radiation induced bystander effects in 3D artificial tissue system and applications for radiation protection

    International Nuclear Information System (INIS)

    The universality of the target theory of radiation-induced effects is challenged by observations on non-targeted effects such as bystander effects. Essential features of non-targeted effects are that they do not require direct nuclear exposure by radiation and they are particularly significant at low doses. This new evidence suggests a need for a new paradigm in radiation biology. The new paradigm should cover both the classical (targeted) and the non-targeted effects. The bystander effect cannot be comprehensively explained on the basis of a single cell reaction. It is well known that an organism is composed of different cell types that interact as functional units in a way to maintain normal tissue function. Therefore the radiation response is not simply the sum of cellular responses as assumed in classical radiobiology, predominantly from studies using cell cultures. Experimental models, which maintain tissue-like intercellular cell signalling and 3D structure, are essential for proper understanding of the bystander effect. Our work relates to experimentation with novel 3D artificial human tissue systems available from MatTek Corporation (Boston, USA). Air-liquid interface culture technique is used to grow artificial tissues, which allow to model conditions present in vivo. The Gray Cancer Institute (Northwood, UK) charged particle microbeam was used to irradiate tissue samples in a known pattern with a known number of 3He2+ particles or protons. After irradiation, the tissues models were incubated for 3 days, fixed in 10 % NBF, paraffin embedded and then sliced into 5 μm histological sections located at varying distances from the plane of the irradiated cells. We studied in situ apoptosis and markers of differentiation. Significantly elevated bystander induced apoptosis was observed with 3'-OH DNA end-labelling based technique in 3D artificial tissue systems. Our results also suggested an importance of proliferation and differentiation status for bystander

  15. Solar ultraviolet radiation, vitamin D and skin cancer surveillance in organ transplant recipients (OTRs): an update.

    Science.gov (United States)

    Reichrath, Jörg

    2014-01-01

    During the last decades, the annual numbers of performed solid organ transplants have continuously increased world-wide. Solid organ transplant recipients (OTR) have a greater risk to develop malignancies, with skin cancer representing the most common neoplasia. Additionally, OTRs in general develop a more aggressive form of malignancies. In consequence, dermatologic surveillance is of high importance for OTRs and these patients represent an increasing and significant challenge to clinicians including dermatologists. In OTRs, patient and organ survival have increased considerably and continuously over the past two decades as a result of better immunosuppressive regimens and better posttransplant care. Great progress has been made in our understanding that individual immunosuppressive regiments differ in their effect on skin cancer risk in OTRs, and that effects of individual immunosuppressive regiments on skin cancer risk depend on various other factors including viral infections. Since sunlight is the major source of vitamin D for most humans, OTRs, who have to protect themselves consequently against solar or artificial UV radiation, are at high risk of developing vitamin D deficiency. Vitamin D deficiency is not only associated with increased risk for metabolic bone disease, but with other severe health problems including various types of malignancies. As a consequence, screening for and treatment of vitamin D deficiency is warranted in OTRs. In this review, we give an update on our present understanding of skin cancer surveillance in OTRs. PMID:25207370

  16. Antimicrobial Effects of Ionizing Radiation on Artificially and Naturally Contaminated Cacao Beans

    OpenAIRE

    Restaino, L; Myron, J. J. J.; Lenovich, L M; Bills, S.; Tscherneff, K.

    1984-01-01

    With an initial microbial level of ca. 107 microorganisms per g of Ivory Coast cacao beans, 5 kGy of gamma radiation under an atmosphere of air reduced the microflora per g by 2.49 and 3.03 logs at temperatures of 35 and 50°C, respectively. Bahia cacao beans were artificially contaminated with dried spores of Aspergillus flavus and Penicillium citrinum, giving initial fungal levels of 1.9 × 104 and 1.4 × 103 spores per g of whole Bahia cacao beans, respectively. The average D10 values for A. ...

  17. Reduction of arsenite-enhanced ultraviolet radiation-induced DNA damage by supplemental zinc

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, Karen L.; King, Brenee S.; Sandoval, Monica M.; Liu, Ke Jian; Hudson, Laurie G., E-mail: lhudson@salud.unm.edu

    2013-06-01

    Arsenic is a recognized human carcinogen and there is evidence that arsenic augments the carcinogenicity of DNA damaging agents such as ultraviolet radiation (UVR) thereby acting as a co-carcinogen. Inhibition of DNA repair is one proposed mechanism to account for the co-carcinogenic actions of arsenic. We and others find that arsenite interferes with the function of certain zinc finger DNA repair proteins. Furthermore, we reported that zinc reverses the effects of arsenite in cultured cells and a DNA repair target protein, poly (ADP-ribose) polymerase-1. In order to determine whether zinc ameliorates the effects of arsenite on UVR-induced DNA damage in human keratinocytes and in an in vivo model, normal human epidermal keratinocytes and SKH-1 hairless mice were exposed to arsenite, zinc or both before solar-simulated (ss) UVR exposure. Poly (ADP-ribose) polymerase activity, DNA damage and mutation frequencies at the Hprt locus were measured in each treatment group in normal human keratinocytes. DNA damage was assessed in vivo by immunohistochemical staining of skin sections isolated from SKH-1 hairless mice. Cell-based findings demonstrate that ssUVR-induced DNA damage and mutagenesis are enhanced by arsenite, and supplemental zinc partially reverses the arsenite effect. In vivo studies confirm that zinc supplementation decreases arsenite-enhanced DNA damage in response to ssUVR exposure. From these data we can conclude that zinc offsets the impact of arsenic on ssUVR-stimulated DNA damage in cells and in vivo suggesting that zinc supplementation may provide a strategy to improve DNA repair capacity in arsenic exposed human populations. - Highlights: • Low levels of arsenite enhance UV-induced DNA damage in human keratinocytes. • UV-initiated HPRT mutation frequency is enhanced by arsenite. • Zinc supplementation offsets DNA damage and mutation frequency enhanced by arsenite. • Zinc-dependent reduction of arsenite enhanced DNA damage is confirmed in vivo.

  18. Reduction of arsenite-enhanced ultraviolet radiation-induced DNA damage by supplemental zinc

    International Nuclear Information System (INIS)

    Arsenic is a recognized human carcinogen and there is evidence that arsenic augments the carcinogenicity of DNA damaging agents such as ultraviolet radiation (UVR) thereby acting as a co-carcinogen. Inhibition of DNA repair is one proposed mechanism to account for the co-carcinogenic actions of arsenic. We and others find that arsenite interferes with the function of certain zinc finger DNA repair proteins. Furthermore, we reported that zinc reverses the effects of arsenite in cultured cells and a DNA repair target protein, poly (ADP-ribose) polymerase-1. In order to determine whether zinc ameliorates the effects of arsenite on UVR-induced DNA damage in human keratinocytes and in an in vivo model, normal human epidermal keratinocytes and SKH-1 hairless mice were exposed to arsenite, zinc or both before solar-simulated (ss) UVR exposure. Poly (ADP-ribose) polymerase activity, DNA damage and mutation frequencies at the Hprt locus were measured in each treatment group in normal human keratinocytes. DNA damage was assessed in vivo by immunohistochemical staining of skin sections isolated from SKH-1 hairless mice. Cell-based findings demonstrate that ssUVR-induced DNA damage and mutagenesis are enhanced by arsenite, and supplemental zinc partially reverses the arsenite effect. In vivo studies confirm that zinc supplementation decreases arsenite-enhanced DNA damage in response to ssUVR exposure. From these data we can conclude that zinc offsets the impact of arsenic on ssUVR-stimulated DNA damage in cells and in vivo suggesting that zinc supplementation may provide a strategy to improve DNA repair capacity in arsenic exposed human populations. - Highlights: • Low levels of arsenite enhance UV-induced DNA damage in human keratinocytes. • UV-initiated HPRT mutation frequency is enhanced by arsenite. • Zinc supplementation offsets DNA damage and mutation frequency enhanced by arsenite. • Zinc-dependent reduction of arsenite enhanced DNA damage is confirmed in vivo

  19. First results of measurements of extreme ultraviolet radiation onboard a geostationary satellite "ELECTRO-L"

    Science.gov (United States)

    Nusinov, Anatoliy; Kazachevskaya, Tamara; Gonjukh, David

    Measurements of the intensity of EUV emission in the hydrogen Lyman-alpha line were conducted by a broadband photometer VUSS-E onboard geostationary Hydrometeorological satellite "Electro" since March 2011. The solar hydrogen Lyman-alpha line (lambda = 121.6 nm) was monitored. The photomultiplier with LiF window used as a detector insensitive to visible light. Long-wavelength limit of the spectral band sensitivity of the instrument is about 200 nm, so the signal of the device is defined as the flux of solar radiation in the region of 123-200 nm. Its exclusion was carried out by calculation. Since the satellite "Electro" designed for remote sensing of the Earth, its line of sight focused on Earth. Alignment of instrument in the Sun direction was achieved by installing it on the solar panel, periodically moved in the solar direction. Correction of instrument readings, reduced due to the deviation of its axis from the Sun direction, carried out by calculation. Measurements were carried out every second. The first results of the measurements are presented. The difference in absolute calibration Electro-L/VUSS-E is within 5% of corresponding values for measurements TIMED satellite in those days, that is in agreement with laboratory calibrations. It is useful to measure the temperature of the instrument, as its variation on a small interval of time makes change the value of the output signal about 1-2 %. During first year of operation, the sensitivity of the apparatus remained within ± 2% of measured value, significant degradation of sensitivity was not observed. Over time of observation there have been several large flares of X class. The increase of the signal in the ultraviolet range does not exceed a few percent during these flares.

  20. Interactive effects of temperature, ultraviolet radiation and food quality on zooplankton alkaline phosphatase activity.

    Science.gov (United States)

    Wolinski, Laura; Modenutti, Beatriz; Souza, Maria Sol; Balseiro, Esteban

    2016-06-01

    Ultraviolet Radiation (UVR) is a stressor for aquatic organisms affecting enzyme activities in planktonic populations because of the increase in reactive oxygen species. In addition, UVR exposure combined with other environmental factors (i.e. temperature and food quality) could have even higher detrimental effects. In this work, we aimed to determine the effect of UVR on somatic Alkaline Phosphatase Activity (APA) and Glutathione S-Transferase (GST) activity on the cladoceran Daphnia commutata under two different temperatures (10 °C and 20 °C) and under three food qualities (carbon:phosphorus ratios: 1150, 850 and 550). APA is a biomarker that is considered as a P deficiency indicator in zooplankton. Since recovery from UVR damage under dark conditions is an ATP depending reaction we also measured APA during recovery phases. We carried out a laboratory experiment combining different temperatures and food qualities with exposition to UVR followed by luminic and dark phases for recovery. In addition, we exposed organisms to H2O2, to establish if the response on APA to UVR was a consequence of the reactive oxygen species produced these short wavelengths. Our results showed that somatic APA was negatively affected by UVR exposure and this effect was enhanced under high temperature and low food quality. Consistently, GST activity was higher when exposed to UVR under both temperatures. The H2O2 experiments showed the same trend as UVR exposure, indicating that APA is affected mainly by oxidative stress than by direct effect of UVR on the enzyme. Finally, APA was affected in the dark phase of recovery confirming the P demands. These results enlighten the importance of food quality in the interacting effect of UVR and temperature, showing that C:P food ratio could determine the success or failure of zooplanktonic populations in a context of global change. PMID:26895537

  1. Strain H2-419-4 of Haematococcus pluvialis induced by ethyl methanesulphonate and ultraviolet radiation

    Science.gov (United States)

    Sun, Yanhong; Liu, Jianguo; Zhang, Xiaoli; Lin, Wei

    2008-05-01

    Two strains H2-410 and H2-419 were obtained from the chemically mutated survivors of wild Haematococcus pluvialis 2 by using ethyl methanesulphonate (EMS). Strains H2-410 and H2-419 showed a fast cell growth with 13% and 20% increase in biomass compared to wild type, respectively. Then H2-419-4, a fast cell growth and high astaxanthin accumulation strain, was obtained by exposing the strain H2-419 to ultraviolet radiation (UV) further. The total biomass, the astaxanthin content per cell, astaxanthin production of H2-419-4 showed 68%, 28%, and 120% increase compared to wild H. pluvialis 2, respectively. HPLC (High Performance Liquid Chromatography) data showed also an obvious proportional variation of different carotenoid compositions in the extracts of H2-419-4 and the wild type, although no peak of carotenoids appeared or disappeared. Therefore, the main compositions in strain H2-419-4, like its wild one, were free of astaxanthin, monoester, and diester of astaxanthin. The asexual reproduction in survivors after exposed to UV was not synchronous, and different from the normal synchronous asexual reproduction as the mother cells were motile instead of non-motile. Interestingly, some survivors from UV irradiation produced many mini-spores (or gamete?), the spores moved away from the mother cell gradually 4 or 5 days later. This is quite similar to sexual reproduction described by Elliot in 1934. However, whether this was sexual reproduction remains questionable, as no mating process has been observed.

  2. Environmental Cues to Ultraviolet Radiation and Personal Sun Protection In Outdoor Winter Recreation

    Science.gov (United States)

    Buller, David B.; Walkosz, Barbara J.; Scott, Michael D.; Maloy, Julie A.; Cutter, Gary R.; Dignan, Mark D.

    2012-01-01

    Objective The prevalence of ultraviolet radiation (UV) at North American ski resorts was predicted using temporal, seasonal, altitudinal, and meteorological factors and associated with a set of adult sun protection behaviors. Design UV observations and cross-sectional survey of adults on sun protection were collected. Setting Data were collected at 32 high-altitude ski areas located in Western North America in 2001–03. Participants The sample consisted of 3,937 adult skier or snowboarders. Main Outcome Measures Measurements of direct, reflected, and diffuse UV were performed at 487 measurement points using handheld meters and combined with self-reported and observed sun protection assessed for adults interviewed on chair lifts. Results The strongest predictors of UV were temporal proximity to noon, deviation from winter solstice, and clear skies. By contrast, altitude and latitude had more modest associations with UV and temperature had a small positive relationship with UV. Guest sun safety was inconsistently associated with UV: UV was positively related to adults wearing more sunscreen, reapplying it after two hours, and wearing protective eyewear but fewer adults exhibited many of the other sun protection behaviors, such as hats, protective clothing or lip balm, on days when UV was elevated. Guests took more sun safety precautions on clear-sky days but took steps to maintain body warmth on inclement days. Conclusions In future sun safety promotions, adults should be encouraged to wear sunscreen on cloudy days because UV is still high and conditions can change rapidly. They need reminders to rely more on season and time of day when judging UV and the need for sun safety. PMID:21079060

  3. Assessment of litter degradation in medicinal plants subjected to ultraviolet-B radiation.

    Science.gov (United States)

    Agrawal, S B; Kumari, Rima

    2013-07-01

    Litter decomposition is an important component of global carbon budget. Elevated influx of ultraviolet-B radiation (UV-B) as a consequence of depletion of stratospheric ozone (O3) layer may affect litter decomposition directly or/modifying the plant tissue quality. Chemical composition of plant can affect litter decomposition. In the present study, three important medicinal plant species i.e. Acorus calamus, Ocimum sanctum and Cymbopogon citratus were exposed to two levels of supplemental UV-B (sUV and sUV,) during the growth period and examined the changes in leaf quality and degradation of leaf litters. The sUV, treatment (+3.6 kJ m(-2) d(-1)) increased the rate of decomposition by 45% and 31% respectively; in leaf litters from O. sanctum and C. citratus, while no significant effect was noticed in A. calamus leaf litter. Higher accumulation of sclerenchymatous tissue around vascular bundles and increased concentrations of total phenols by 39 mg g(-1) probably lowered the decomposition rate; finding k value: 0.0049 g g(-1) d(-1) in leaf litters of A. calamus. The C/N ratio was increased by 14% at sUV2 in C. citratus, whereas in O. sanctum it decreased by 13.6% after treatment. Results of the present experiment illustrates that firstly UV-B can modify the decomposition rate of leaf litter of test plant species, secondly it can alter the tissue chemistry particularly leaf phenolics, N and P concentrations strongly and thus affecting the decay rate and thirdly UV-B effects on decay rate and leaf chemistry is species specific. PMID:24640251

  4. Impact of enhanced ultraviolet-B radiation on flower, pollen, and nectar production

    International Nuclear Information System (INIS)

    Intensified ultraviolet-B radiation or UV-B (wavelengths between 280 and 320 nm) can delay flowering and diminish lifetime flower production in a few plants. Here we studied the effects of enhanced UV-B on floral traits crucial to pollination and pollinator reproduction. We observed simultaneous flowering responses of a new crop plant, Limnanthes alba (Limnathaceae), and a wildflower, Phacelia campanularia (Hydrophyllaceae), to five lifetime UV-B dosages ranging between 2.74 and 15.93 kJ·m-2·d-1. Floral traits known to link plant pollination with bee host preference, host fidelity and larval development were measured. Intensified UV-B had no overall effect on nectar and pollen production of L. alba and P. campanularia flowers. A quadratic relationship between UV-B and nectar sugar production occurred in P. campanularia and showed that even subambient UV-B dosages can be deleterious for a floral trait. Other floral responses to UV-B were more dramatic and idiosyncratic. As UV-B dosage increased, L. alba plants were less likely to flower, but suffered no delays in flowering or reductions to lifetime flower production for those that did flower. Conversely, an equal proportion of P. campanularia plants flowered under all UV-B treatments, but these same plants experienced delayed onset to bloom and produced fewer flowers at greater UV-B intensities. Therefore, intensified UV-B elicits idiosyncratic responses in flowering phenology and flower production from these two annual plants. Diurnal patterns in nectar and pollen production strongly coincided with fluctuating humidity and only weakly with UV-B dosage. Overall, our results indicated that intensified UVB can alter some flowering traits that impinge upon plant competition for pollinator services, as well as plant and pollinator reproductive success. (author)

  5. Strain H2-419-4 of Haematococcus pluvialis induced by ethyl methanesulphonate and ultraviolet radiation

    Institute of Scientific and Technical Information of China (English)

    SUN Yanhong; LIU Jianguo; ZHANG Xiaoli; LIN Wei

    2008-01-01

    Two strains H2-410 and H2-419 were obtained from the chemically mutated survivors of wild Haematococcus pluvialis 2 by using ethyl methanesulphonate (EMS).Strains H2-410 and H2-419 showed a fast cell growth with 13% and 20% increase in biomass compared to wild type,respectively.Then H2-419-4,a fast cell growth and high astaxanthin accumulation strain,was obtained by exposing the strain H2-419 to ultraviolet radiation (UV) further.The total biomass,the astaxanthin content per cell,astaxanthin production of H2-419-4 showed 68%,28%,and 120% increase compared to wild H.pluvialis 2,respectively.HPLC (High Performance Liquid Chromatography) data showed also an obvious proportional variation of different carotenoid compositions in the extracts of H2-419-4 and the wild type,although no peak of carotenoids appeared or disappeared.Therefore,the main compositions in strain H2-419-4,like its wild one,were free of astaxanthin,monoester,and diester of astaxanthin.The asexual reproduction in survivors after exposed to UV was not synchronous,and different from the normal synchronous asexual reproduction as the mother cells were motile instead of non-motile.Interestingly,some survivors from UV irradiation produced many mini-spores (or gamete?),the spores moved away from the mother cell gradually 4 or 5 days later.This is quite similar to sexual reproduction described by Elliot in 1934.However,whether this was sexual reproduction remains questionable,as no mating process has been observed.

  6. Mutagenesis and selection of high efficiency hydrogen producing mutants by ultraviolet radiation

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Hydrogen is an ideal, clean and sustainable energy source for the future because of its high conversion and nonpolluting nature. Biohydrogen production by dark-fermentation appears to have a great potential to be developed for practical application. However, one limiting factor affecting the development of hydrogen-production industrialization is that the hydrogen-producing capacity of bacteria is lower, so how to increase bacteria's hydrogen-producing ability will be an urgent issue. In this experiment, 2 mutants, namely UV3 and UV7,were obtained by ultra-violet radiation. They grew and produced hydrogen efficiently on iron-containing medium. The hydrogen evolution of UV3 and UV7 were 2 356. 68 ml/L and 2 219. 62 ml/L at a glucose concentration of 10 g/L, respectively. With wild parent strain Ethanoligenens sp. ZGX4, the hydrogen evohution was 1 806. 02 ml/L under the same conditions. Mutants' hydrogen-producing capacities were about 29. 71% and 22.22% higher than that of wild parent strain ZGX4. The maximum H2 production rate by mutants UV3 and UV7 were estimated to be 32. 57 mmol H2/g cell h and 31.19 mmol H2/g cell h, respectively, which were 38. 18% and 34. 78% higher than the control (23.57 mmol H2/g cell h). The abundant products of UV3 and UV7 were ethanol and acetic, which accounted for 95% -98% of total soluble microbial products. In each case, mutant strains UV3 and UV7 evolved hydrogen at a higher rate than the wild type, showing a possible potential for commercial hydrogen production. Another mutant named UV20' was also gained whose main end metabolites were butyric acid and acetic acid. This would provide researched material for a discussion of metabolic pathways of hydrogen-producing bacteria.

  7. Can ultraviolet radiation act as a survival enhancer for cutaneous melanoma?

    Science.gov (United States)

    Mastroeni, Simona; Bonamigo, Renan; Mannooranparampil, Thomas; Marino, Claudia; Michelozzi, Paola; Passarelli, Francesca; Boniol, Mathieu

    2016-01-01

    Some studies have suggested that sun exposure plays a protective role in melanoma survival. This created a paradox as the known carcinogen can act as a cancer promoter and also as a survival enhancer. The aim of this study was to investigate the effect of sun exposure on melanoma mortality using both ambient sun exposure and individual data. A 10-year cohort study was carried out on primary cutaneous melanoma cases (n=972). Residential data were coupled with levels of ultraviolet radiation (UV) to provide a measure of individual exposure. Demographic, histological and clinical data were obtained for all participants. In a subsample, information on pigmentary characteristics, diet, medical history, phenotype and self-reported sun exposure was also collected. Survival analysis and Cox proportional hazards models were used to examine associations. No protective effect was found for UVB or individual sun exposure variables on melanoma mortality. However, an increased risk of mortality was found among patients with cutaneous melanoma located on the lower limbs and in the highest decile of UVB exposure (≥3.298 J/cm2) after controlling for sex, age and Breslow thickness (relative risk: 4.78; 95% confidence interval: 1.30–17.5). The increased risk of mortality for the highest decile of UVB was also confirmed in the subsample after controlling for sex, age, education, use of sun lamps, pigmentary characteristics and diet. The results of the study suggested no protective effect of sun exposure for melanoma mortality and showed that high sun exposure increases the risk of melanoma mortality among patients with melanomas located on the lower limbs. PMID:25646933

  8. Deleterious effect of ultraviolet-B radiation on accessory function of human blood adherent mononuclear cells

    International Nuclear Information System (INIS)

    The effects of ultraviolet-B radiation (UV-B) on accessory function of human blood adherent mononuclear cells (ADH) for antigen and mitogen-induced responses, and production by ADH of the amplifying cytokine interleukin 1 (IL-1) were examined. Responder lymphocytes were rendered accessory cell dependent by treatment of nonadherent cells with OKIal + complement. UV-B depressed accessory function of ADH in a dose-dependent manner. UV-B decreased accessory function of ADH for tetanus toxoid-induced responses and phytohaemagglutinin-induced responses. UV-B also decreased accessory activity of peripheral blood mononuclear cells but not Epstein-Barr virus-transformed B cells for a PPD-reactive T cell line. Interleukin 1 (IL-1) activity of supernatants of ADH was assayed on C3H/HeJ mouse thymocytes. Pretreatment of ADH with UV-B decreased lipopolysaccharide-stimulated IL-1 activity. Lysates of UV-B irradiated, LPS-stimulated ADH had no discernible IL-1 activity. Addition of IL-1 partially restored accessory activity of UV-B irradiated ADH for lymphocyte responses to TT. Exposure of ADH to TT or PHA for 30 min before irradiation blocked the inhibitory effect of UV-B on accessory activity. Thus, low doses of UV-B are deleterious to accessory function and to production of IL-1 by ADH. Interference with production of cytokines and with initial interactions of accessory cells with antigen and mitogen may be critical to the effects of UV-B on immunoregulatory function of ADH. (author)

  9. Persistent polar depletion of stratospheric ozone and emergent mechanisms of ultraviolet radiation-mediated health dysregulation.

    Science.gov (United States)

    Dugo, Mark A; Han, Fengxiang; Tchounwou, Paul B

    2012-01-01

    Year 2011 noted the first definable ozone "hole" in the Arctic region, serving as an indicator to the continued threat of dangerous ultraviolet radiation (UVR) exposure caused by the deterioration of stratospheric ozone in the northern hemisphere. Despite mandates of the Montreal Protocol to phase out the production of ozone-depleting chemicals (ODCs), the relative stability of ODCs validates popular notions of persistent stratospheric ozone for several decades. Moreover, increased UVR exposure through stratospheric ozone depletion is occurring within a larger context of physiologic stress and climate change across the biosphere. In this review, we provide commentaries on stratospheric ozone depletion with relative comparisons between the well-known Antarctic ozone hole and the newly defined ozone hole in the Arctic. Compared with the Antarctic region, the increased UVR exposure in the Northern Hemisphere poses a threat to denser human populations across North America, Europe, and Asia. In this context, we discuss emerging targets of UVR exposure that can potentially offset normal biologic rhythms in terms of taxonomically conserved photoperiod-dependent seasonal signaling and entrainment of circadian clocks. Consequences of seasonal shifts during critical life history stages can alter fitness and condition, whereas circadian disruption is increasingly becoming associated as a causal link to increased carcinogenesis. We further review the significance of genomic alterations via UVR-induced modulations of phase I and II transcription factors located in skin cells, the aryl hydrocarbon receptor (AhR), and the nuclear factor (erythroid-derived 2)-related factor 2 (Nrf2), with emphasis on mechanism that can lead to metabolic shifts and cancer. Although concern for adverse health consequences due to increased UVR exposure are longstanding, recent advances in biochemical research suggest that AhR and Nrf2 transcriptional regulators are likely targets for UVR

  10. Green tea catechins and their metabolites in human skin before and after exposure to ultraviolet radiation.

    Science.gov (United States)

    Clarke, Kayleigh A; Dew, Tristan P; Watson, Rachel E B; Farrar, Mark D; Osman, Joanne E; Nicolaou, Anna; Rhodes, Lesley E; Williamson, Gary

    2016-01-01

    Dietary flavonoids may protect against sunburn inflammation in skin. Preliminary reports using less complete analysis suggest that certain catechins and their metabolites are found in skin biopsies and blister fluid after consumption of green tea; however, it is not known if they are affected by solar-simulated ultraviolet radiation (UVR) or whether conjugated forms, with consequently altered bioactivity, are present. The present study tested the hypothesis that UVR affects the catechin levels in the skin of healthy volunteers after consumption of green tea and how catechins in the plasma are related to their presence in skin tissue samples. In an open oral intervention study, 11 subjects consumed green tea and vitamin C supplements daily for 3months. Presupplementation and postsupplementation plasma samples, suction blister fluid and skin biopsies were collected; the latter two samples were collected both before and after UVR. A sensitive high-performance liquid chromatography/mass spectrometric assay was used to measure the intact catechin metabolites, conjugates and free forms. Seven green tea catechins and their corresponding metabolites were identified postsupplementation in skin biopsies, 20 in blister fluid and 26 in plasma, with 15 green tea catechin metabolites present in both blister fluid and plasma. The valerolactone, O-methyl-M4-O-sulfate, a gut microbiota metabolite of catechins, was significantly increased 1.6-fold by UVR in blister fluid samples. In conclusion, there were some common catechin metabolites in the plasma and blister fluid, and the concentration was always higher in plasma. The results suggest that green tea catechins and metabolites are bioavailable in skin and provide a novel link between catechin metabolites derived from the skin and gut microbiota. PMID:26454512

  11. Dual calibrated dosimeter for simultaneous measurements of erythemal and vitamin D effective solar ultraviolet radiation.

    Science.gov (United States)

    Wainwright, L; Parisi, A V; Downs, N

    2016-04-01

    A miniaturized ultraviolet radiation (UV) dosimeter based on polyphenylene oxide (PPO) has been dual calibrated for both erythemal and vitamin D effective exposures (UVB 280 - 320nm) over extended periods up to five days. Optimal human health requires a balanced amount of UVB exposure as both too much and too little have different but serious potential health consequences. Dosimetry is an established method of measuring specific UV exposures to an object or subject. PPO dosimeters have previously been used to measure the erythemally effective UV exposure. An extension of this use is to dual calibrate the miniaturized dosimeter which will also enable measurement of vitamin D effective exposures. By calibration to the erythemal and vitamin D effective action spectra, PPO dosimeters were able to record both types of biologically effective exposure as both are active within the UVB waveband. Dose response tests were conducted in each season by exposure to solar UV with the corresponding dual calibrations made for each season. The calibration provided an R(2) of 0.95-0.99 for erythemal UV and an R(2) of 0.99 for vitamin D effective UV. The successful outcome of this testing has established that PPO is suitable for use as a long term, dual calibrated dosimeter provided the film is seasonally calibrated. This enables one dosimeter to provide two sets of exposure results. The combination of dual calibration and the long term exposure potential of PPO makes the PPO dosimeter more versatile and increases the scope of UV field research on erythemal UV and vitamin D effective UV in the future. PMID:26878218

  12. Climate and ozone change effects on ultraviolet radiation and risks (COEUR). Using and validating earth observation

    Energy Technology Data Exchange (ETDEWEB)

    Van Dijk, A; Den Outer, P.N.; Slaper, H.

    2008-06-15

    The AMOUR2.0 (Assessment Model for Ultraviolet radiation and Risks) model is presented. With this model it is possible to relate ozone depletion scenarios to (changes in) skin cancer incidence. The estimation of UV maps is integrated in the model. The satellite-based method to estimate UV maps is validated for EPTOMS (Earth Probe - Total Ozone Mapping Spectrometer) data against ground measurements for 17 locations in Europe. For most ground stations the estimates for the yeardose agree within 5%. Deviations are related to high ground albedo. A suggestion has been made for improvement of the albedo-correction. The AMOUR2.0 UV estimate was found to correspond better with ground measurements than the models from NASA (National Aeronautics and Space Administration in the USA), TEMIS (Tropospheric Emission Monitoring Internet Service of the European Space Agency ESA) and FMI (Finnish Meteorological Institute). The EPTOMS-UV product and the FMI model overestimate the UV dose. The TEMIS model has a good clear-sky correspondence with ground measurement, but overestimates UV in clouded situations. Satellite measurements of ozone and historic chlorine level have been used to make global estimates for future ozone levels for a collection of emission scenarios for ozone depleting substances. Analysis of the 'best guess' scenario, shows that the minimum in ozone level will be reached within 15 years from now. In 2050 the UV dose for Europe will to a large extent have returned to the values observed in 1980 if there is no climate-change driven alteration in cloud patterns. Future incidence maps up to the year 2100 are estimated with the dose-effect relation presented in an earlier study. This is done for three UV related types of skin-cancer: Basal Cell Carcinoma (BCC), Squamous Cell Carcinoma (SCC) and Cutaneous Malignant Melanoma (CMM). For a stationary population, global incidences of BCC and CMM are expected to peak around the year 2065 and for SCC around 2040.

  13. Photoionization of epichlorohydrin enantiomers and clusters studied with circularly polarized vacuum ultraviolet radiation.

    Science.gov (United States)

    Daly, Steven; Powis, Ivan; Garcia, Gustavo A; Soldi-Lose, Héloïse; Nahon, Laurent

    2011-02-14

    The photoionization of enantiomerically pure epichlorohydrin (C(3)H(5)OCl) has been studied using linearly and circularly polarized vacuum ultraviolet synchrotron radiation. The threshold photoelectron spectrum was recorded and the first three bands assigned using molecular orbital calculations for the expected conformers, although uncertain experimental conformer populations and an anticipated breakdown in Koopmans' theorem leave some ambiguity. Measurements of the photoelectron circular dichroism (PECD) were obtained across a range of photon energies for each of these bands, using electron velocity map imaging to record the angular distributions, during which a record PECD chiral asymmetry factor of 32% was observed. A comparison with calculated PECD curves clarifies the assignment achieved using ionization energies alone and further suggests a likely relative population of the conformers. Threshold photoelectron-photoion coincidence methods were used to study the ionic fragmentation of epichlorohydrin. Fragment ion appearance energies show nonstatistical behavior with clear indications that the cationic epoxide ring is unstable and lower energy decay channels proceeding via ring breaking are generally open. Extensive neutral homochiral clusters of epichlorohydrin may be formed in supersonic molecular beam expansions seeded in Ar. Electron angular distribution measurements made in coincidence with dimer and trimer ions are used to effect an examination of the PECD associated with ionization of size-selected neutral cluster species, and these results differ clearly from PECD of the neutral monomer. The shifted ionization thresholds of the n-mers (n = 2, ..., 7) are shown to follow a simple linear relationship, but under intense beam expansion conditions the monomer deviates from this relationship, and the monomer electron spectra tail to below the expected monomer adiabatic ionization potential (IP). PECD measurements made in coincidence with monomer ions obtained

  14. Determination of the dosimetric properties of ZrO2: Cu and it use in the ultraviolet radiation dosimetry

    International Nuclear Information System (INIS)

    In this work the experimental results of studying the thermoluminescent characteristics (TL) of the zirconium oxide doped with copper (ZrO2: Cu) exposed to ultraviolet light of wavelength in the interval of 200-400 nm are presented. The material in powder form was prepared using the sol-gel method. The dosimetric characteristics studied includes the emission curve TL (curved TL), the thermoluminescent response in function of the wavelength, the minimum dose detectable and the lineality of the response. The TL response of the ZrO2: Cu in function of the wavelength presents two maxima, in 260 and 290 nm, respectively. The TL curve of the ZrO2: Cu showed two peaks, in 120 and 170 C, respectively, being its similar form for all the studied wavelengths. The response in function of the spectral irradiance results to be lineal in the interval from 160 to 2300 mJ/cm2. The obtained results when studying the TL properties of ZrO2: Cu exposed to the ultraviolet radiation show that it gathers dosimetric characteristics prominent to be used as an ultraviolet radiation dosemeter. (Author)

  15. Protective Effect of Topically Applied Polypeptide from Chlamys farreri Against Ultraviolet Radiation-Induced Chronic Skin Damage in Guinea Pig

    Institute of Scientific and Technical Information of China (English)

    迟明亮; 曹鹏利; 于国英; 朱莉; 王跃军; 王春波

    2003-01-01

    Polypeptide from Chlamys farreri (PCF) , a topical polypeptide isolated from Chlamys farreri, was used in this experiment aimed to investigate the photoprotective effect of PCF against chronic skin damage induced by ultraviolet A (UVA) and ultraviolet B (UVB) radiation. The chronic ultraviolet-irradiated guinea pig model was established, and visible changes in the skin including wrinkling, sagging and erythema were observed. Malondialdehyde (MDA) and antioxidant enzymes including superoxide dismutase (SOD) and glutathione peroxidase (GSH-px) in the dorsal skin were determined using biochemical methods. The results showed:(1)PCF (5 % and 20%) could greatly protect the dorsal skin of guinea pig against wrinkling, sagging and erythema induced by UV radiation in a concentration-dependent manner.(2)PCF could reduce MDA formation in the dorsal skin caused by UV irradiation, while increasing the activities of SOD and GSH-px.(3)The differences among the PCF groups and UV model group were significant (P<0.05, P<0.01). These results indicated that topical application of PCF provided broad solar UV spectrum photoprotection; and that the antioxidant property of PCF might play a role in photoprotection.

  16. Study of the influence of ultraviolet radiation on aggregative properties of blood red cell by light backscattering

    International Nuclear Information System (INIS)

    The method based on the fact of measurable intensity of backscattered laser beam resulting from the angular distribution of scattered light is investigated. The method permits study of the mechanisms of aggregation and disaggregation processes by ultraviolet radiation and action of some inductors. The ultraviolet light acting directly on erythrocyte rouleaus of 10 x 100 μ causes the scattering of laser beam of wavelength 632,8 nm. According the above mentioned fact at an agle of approximately 1800 the light intensity is measured. Stabilized blood sample is exposed to laser beam by means of fiber optics. Backscattering light transmitted through the photomultiplier and direct current supply is recorded. Quantitative concept of erythrocyte aggregation process is calculated from the plot. Blood sample is mixed by magnetic mixer and the measuring temperature is kept constantly at 370C. Accordingly, the present model can adequately reproduce complex blood red cells kinetics. The influence of ultraviolet radiation and different kinds of inductors on erythrocytes' aggregation is experimentally studied depending on time. 2 figs. (B.Sh.)

  17. Interactive effects on CO2, drought, and ultraviolet-B radiation on maize growth and development.

    Science.gov (United States)

    Wijewardana, Chathurika; Henry, W Brien; Gao, Wei; Reddy, K Raja

    2016-07-01

    Crop growth and development are highly responsive to global climate change components such as elevated carbon dioxide (CO2), drought, and ultraviolet-B (UV-B) radiation. Plant tolerance to these environmental stresses comprises its genetic potential, physiological changes, metabolism, and signaling pathways. An inclusive understanding of morphological, physiological, and biochemical responses to these abiotic stresses is imperative for the development of stress tolerant varieties for future environments. The objectives of this study were to characterize the changes in vegetative and physiological traits in maize hybrids in their response to multiple environmental factors of (CO2) [400 and 750μmolmol(-1) (+(CO2)], irrigation treatments based evapotranspiration (ET) [100 and 50% (-ET)], and UV-B radiation [0 and 10kJm(-2)d(-1) (+UV-B)] and to identify the multiple stress tolerant hybrids aid in mitigating projected climate change for shaping future agriculture. Six maize hybrids (P1498, DKC 65-81, N75H-GTA, P1319, DKC 66-97, and N77P-3111) with known drought tolerance variability were grown in eight sunlit, controlled environment chambers in which control treatment consisted of 400μmolmol(-1) [CO2], 100% ET-based irrigation, and 0kJ UV-B. Plants grown at +UV-B alone or combination with 50% ET produced shorter plants and smaller leaf area while elevated CO2 treatments ameliorated the damaging effects of drought and higher UV-B levels on maize hybrids. Plant height, leaf area, total dry matter chlorophyll, carotenoids, and net photosynthesis measured were increased in response to CO2 enrichment. Total stress response index (TSRI) for each hybrid, developed from the cumulative sum of response indices of vegetative and physiological parameters, varied among the maize hybrids. The hybrids were classified as tolerant (P1498), intermediate (DKC 65-81, N75H-GTA, N77P-3111) and sensitive (P1319 and DKC 66-97) to multiple environmental stresses. The positive correlation

  18. The Efficacy of Ultraviolet Radiation for Sterilizing Tools Used for Surgically Implanting Transmitters into Fish

    Energy Technology Data Exchange (ETDEWEB)

    Walker, Ricardo W.; Markillie, Lye Meng; Colotelo, Alison HA; Gay, Marybeth E.; Woodley, Christa M.; Brown, Richard S.

    2013-02-28

    Telemetry is frequently used to examine the behavior of fish, and the transmitters used are normally surgically implanted into the coelom of fish. Implantation requires the use of surgical tools such as scalpels, forceps, needle holders, and sutures. When several fish are implanted consecutively for large telemetry studies, it is common for surgical tools to be sterilized or, at minimum, disinfected between each use so that pathogens that may be present are not spread among fish. However, autoclaving tools can take a long period of time, and chemical sterilants or disinfectants can be harmful to both humans and fish and have varied effectiveness. Ultraviolet (UV) radiation is commonly used to disinfect water in aquaculture facilities. However, this technology has not been widely used to sterilize tools for surgical implantation of transmitters in fish. To determine its efficacy for this application, Pacific Northwest National Laboratory researchers used UV radiation to disinfect surgical tools (i.e., forceps, needle holder, stab scalpel, and suture) that were exposed to one of four aquatic organisms that typically lead to negative health issues for salmonids. These organisms included Aeromonas salmonicida, Flavobacterium psychrophilum, Renibacterium salmoninarum, and Saprolegnia parasitica. Surgical tools were exposed to the bacteria by dipping them into a confluent suspension of three varying concentrations (i.e., low, medium, high). After exposure to the bacterial culture, tools were placed into a mobile Millipore UV sterilization apparatus. The tools were then exposed for three different time periods—2, 5, or 15 min. S. parasitica, a water mold, was tested using an agar plate method and forceps-pinch method. UV light exposures of 5 and 15 min were effective at killing all four organisms. UV light was also effective at killing Geobacillus stearothermophilus, the organism used as a biological indicator to verify effectiveness of steam sterilizers. These

  19. An artificial-vision responsive to patient motions during computer controlled radiation therapy

    International Nuclear Information System (INIS)

    Purpose/Objectives: Automated precision radiotherapy using multiple conformal and modulated beams, requires monitoring of patient movements during irradiation. Immobilizers relying on patient cooperating in cradles have somewhat reduced positional uncertainties, but others including breathing are largely unknown. We built an artificial vision (AV) device for real-time vision of patient movements, their tracking and quantification. Method and Materials: The Artificial Vision System's 'acuity' and 'reflex' were evaluated in terms of imaged skin spatial resolutions and temporal dispersions measured using a mannequin and a fiduciated harmonic oscillator placed at 100cm isocenter. The device traced skin motion even in poorly lighted rooms without use of explicit skin fiduciation, or using standard radiotherapy skin tattoos. Results: The AV system tracked human skin at vision rates approaching 30Hz and sensitivity of 2mm. It successfully identified and tracked independent skin marks, either natural tattoos or artificial fiducials. Three alert levels triggered when patient movement exceeded preset displacements (2mm/30Hz), motion velocities (5m/sec) or acceleration (2m/sec2). Conclusion: The AV system trigger should suit for patient ventilatory gating and safety interlocking of treatment accelerators, in order to modulate, interrupt, or abort radiation during dynamic therapy

  20. Enhancement of Candida albicans killing activity of separated human epidermal cells by ultraviolet radiation

    International Nuclear Information System (INIS)

    Ultraviolet irradiation enhanced the Candida albicans killing activity of freshly separated human epidermal cells in vitro. The simulation was dose-dependent and was not due to soluble extracellular factors acting on non-irradiated epidermal cells. The enhancement of the killing activity remained unchanged when epidermal cells were depleted of Langerhans cells. Protein synthesis inhibitors and prostaglandin antagonists inhibited the ultraviolet-induced augmentation of killing activity. (author)

  1. Response of sugar beet plants to ultraviolet-B (280-320 nm) radiation and Cercospora leaf spot disease

    International Nuclear Information System (INIS)

    Sugar beet (Beta vulgaris L.) plants injected with Cercospora beticola Sacc. as well as non-infected plants were grown under visible light with or without ultraviolet-B (UV-B, 280-320 nm) radiation for 40 days. An interaction between UV-B radiation and Cercospora leaf spot disease was observed, resulting in a large reduction in leaf chlorophyll content, dry weight of leaf laminae, petioles and storage roots. Lipid peroxidation in leaves also increased the most under the combined treatments. This was also true for ultraweak luminescence from both adaxial and abaxial leaf surfaces. However, no correlation between lipid peroxidation and ultraweak luminescence was observed. Ultraviolet-B radiation given alone appeared to have either a stimulating effect, giving an increase in dry weight of laminac and reducing lipid peroxidation, or no effect. This lack of effect was seen in the absence of change in dry weight of storage roots and chlorophyll content relative to controls. The study demonstrated a harmful interaction between UV-B radiation and Cercospora leaf spot disease on sugar beet

  2. Comparison of the lithographic properties of positive resists upon exposure to deep- and extreme-ultraviolet radiation

    International Nuclear Information System (INIS)

    Nineteen chemically amplified ultrathin resists were imaged using exposure to extreme-ultraviolet (EUV) (13.4 nm) and deep-ultraviolet (DUV) (248 nm) radiation. Direct comparisons were made of photospeed, resolution, and line edge roughness (LER). The photospeed of these resists at 248 nm shows a good correlation with photospeed at EUV for three polymer types, but appears independent of photoacid generator type. This result underscores the importance of the polymer in photoacid generation at EUV. Resolution showed poor correlation between DUV and EUV. Correlations were made between the line edge roughness of EUV-imaged features and unexposed film thickness loss, resist contrast, image log slope (ILS), and LER of resists exposed at DUV. Both contrast and image log slope play important roles in defining LER performance--where the best LER is achieved at high contrast and high ILS. (c) 1999 American Vacuum Society

  3. Cancer risk at low doses of ionizing radiation: artificial neural networks inference from atomic bomb survivors.

    Science.gov (United States)

    Sasaki, Masao S; Tachibana, Akira; Takeda, Shunichi

    2014-05-01

    Cancer risk at low doses of ionizing radiation remains poorly defined because of ambiguity in the quantitative link to doses below 0.2 Sv in atomic bomb survivors in Hiroshima and Nagasaki arising from limitations in the statistical power and information available on overall radiation dose. To deal with these difficulties, a novel nonparametric statistics based on the 'integrate-and-fire' algorithm of artificial neural networks was developed and tested in cancer databases established by the Radiation Effects Research Foundation. The analysis revealed unique features at low doses that could not be accounted for by nominal exposure dose, including (i) the presence of a threshold that varied with organ, gender and age at exposure, and (ii) a small but significant bumping increase in cancer risk at low doses in Nagasaki that probably reflects internal exposure to (239)Pu. The threshold was distinct from the canonical definition of zero effect in that it was manifested as negative excess relative risk, or suppression of background cancer rates. Such a unique tissue response at low doses of radiation exposure has been implicated in the context of the molecular basis of radiation-environment interplay in favor of recently emerging experimental evidence on DNA double-strand break repair pathway choice and its epigenetic memory by histone marking. PMID:24366315

  4. Effects of gamma rays, ultraviolet radiation, sunlight, microwaves and electromagnetic fields on gene expression mediated by human immunodeficiency virus promoter

    International Nuclear Information System (INIS)

    Previous work by our group and others has shown the modulation of human immunodeficiency virus (HIV) promoter or long terminal repeat (LTR) after exposure to neutrons and ultraviolet radiations. Using HeLa cells stably transfected with a construct containing the chloramphenicol acetyl transferase (CAT) gene, the transcription of which is mediated by the HIV-LTR, we designed experiments to examine the effects of exposure to different types of radiation (such as γ rays, ultraviolet and sunlight irradiations, electromagnetic fields and microwaves) in HIV-LTR-driven expression of CAT. These results demonstrated ultraviolet-light-induced transcription from the HIV promoter, as has been shown by others. Exposure to other DNA-damaging agents such as γ rays and sunlight (with limited exposures) had no significant effect on transcription mediated by HIV-LTR, suggesting that induction of HIV is not mediated by just any type of DNA damage but rather may require specific types of DNA damage. Microwaves did not cause cell killing when cells in culture were exposed in high volumes of medium, and the same cells showed no changes in expression. When microwave exposure was carried out in low volumes of medium (so that excessive heat was generated) induction of HIV-LTR transcription (as assayed by CAT activity) was evident. Electromagnetic field exposures had no effect on expression of HIV-LTR. These results demonstrate that not all types of radiation and not all DNA-damaging agents are capable of inducing HIV. We hypothesize that induction of HIV transcription may be mediated by several different signals exposure to radiation. 22 refs., 8 figs

  5. Influence of small dozes ultra-violet radiation on motion of dislocation in alkali-halide crystals

    Institute of Scientific and Technical Information of China (English)

    Victor; A.; Feodorov; Tatjana.; N.; Plushnikova; Andrey; V.; Chivanov; Margarita; V.Chemerkina; Roman; A.; Kirillov.

    2005-01-01

    The purpose of this work was research into influence of ultra-violet radiation on size of run of regional and screw dislocations in beams of dislocation sockets, formed at indentation surface of alkali-halide crystals. In experiments it was used crystals NaCl, with the quantitative maintenance of impurity 10-2 -10-3weight%, the wave length of UV-radiation λ=250 nanometers, the sizes of samples 10mm× 20mm× 2mm,temperature of samples was constant T=290 K.It is established that indentation and the simultaneous irradiation of samples a ultraviolet is increases size of run of head dispositions in dislocation sockets..It is marked, that influence UV-radiation nonequivalence for various times of an exposition. At small times (till 5 minutes) the size of run grows. The length of beams increases on ~ 50 %. At the further increase in time of influence of a ultraviolet the length of beams is reduced till the sizes corresponding stressing without an irradiation (Figs. 1, 2, 3). The effect is observed on dislocation beams of regional and screw orientations and most expressed at small loadings (in our experiments-10 grams) (Fig. 3).Observable effects are explained from positions dislocation-exciton interactions. At UV-radiation exciton cooperates with the charged step on a disposition, causing movement of a step along a disposition on one internuclear distance. Due to this interaction overcoming by a disposition of a grid of stoppers is facilitated.Big times of endurance cause a relaxation of pressure directly in a print that provides convertible movement of dispositions in area of a print and as consequence, reduction of length of beams of dislocation sockets.

  6. A radiation-induced breast cancer following artificial pneumothorax therapy for pulmonary tuberculosis

    International Nuclear Information System (INIS)

    A case of radiation-induced breast cancer in a woman who had been fluoroscopied repeatedly for control of pneumothorax for pulmonary tuberculosis 35 years before is reported. The breast tissue presumably received about 136 rads or less in three and a half years. In Japan, both prospective and retrospective surveies following multiple fluoroscopies during artificial pneumothorax collaps therapy have failed to show an increase in the risk of subsequent development of primary breast cancer. The dose given to breast tissues in Japanese patients was generally far less than that in the MacKenzie's series. A radiation-induced breast cancer in Japanese literature has not yet been reported. It seems that the lesser doses may explain the reason of this fact. (auth.)

  7. Effect of Rare Earths on Plants under Supplementary Ultraviolet-B Radiation: Ⅱ. Effect of Cerium on Antioxidant Defense System in Rape Seedlings under Supplementary Ultraviolet-B Radiation

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Effects of cerium (Ce3 + ) on membranous protective enzymes in rape seedlings exposed to two levels of enhanced ultraviolet-B radiation (UV-B, 280 ~ 320 nm) were studied by hydroponics in the laboratory. The results show that the chlorophyll content decreases and membrane permeability increases in the leaves under UV-B irradiation with an intenposed to a low level of UV-B radiation. POD activity in leaves exposed to a high level of UV-B radiation is enhanced constantly. The sensitivities of these enzymes to UV-B radiation are SOD > CAT > POD. The injury by UV-B radiation on the functions of protective enzymes is lightened, their ability to scavenge radicals is improved, and the membrane permeability is maintained by Ce. Furthermore, the protective effect of cerium is more obvious in plants exposed to low levels of UV-B radiation than to high levels of it. Accordingly, all results prove that the protective effect of Ce on plants under UV-B radiation is realized through the protective system of plants.

  8. Mutant rodent cell lines sensitive to ultraviolet light, ionizing radiation and cross-linking agents; A comprehensive survey of genetic and biochemical characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Collins, A.R. (Aberdeen University (United Kingdom). Department of Molecular and Cell Biology)

    1993-01-01

    Mutant rodent cell lines with hypersensitivity to DNA damage resulting from a defect in cellular response to the damage have contributed to many recent advances in our knowledge of DNA-repair processes. Many of these mutants have been classified by genetic complementation analysis. They proved excellent recipients of human DNA in transfection experiments, and from those transfectants with restored resistance to DNA damage it has been possible to isolate the foreign DNA responsible for correcting the defect. Several human genes coding for DNA-repair proteins have now been cloned. Until recently, there was apparently no correlation at the genetic level between artificially produced rodent mutants and the inherited human diseases associated with sensitivity to DNA-damaging agents, but several of the human genes cloned in rodent mutants now turn out to correct defects in cells representing the human diseases, too. Others are homologous to yeast DNA-repair genes, and it is clear that at least some of the proteins involved in DNA-repair are highly conserved through evolution. Mutants have provided material for comparative biochemical studies of DNA repair too, and we are nearer to understanding the complexities of this process. This article presents tables that list rodent mutant cell lines sensitive to ultraviolet light, to ionizing radiation and to cross-linking agents. (author). 126 refs., 3 tabs.

  9. An artificial neural network ensemble model for estimating global solar radiation from Meteosat satellite images

    International Nuclear Information System (INIS)

    An optimized artificial neural network ensemble model is built to estimate daily global solar radiation over large areas. The model uses clear-sky estimates and satellite images as input variables. Unlike most studies using satellite imagery based on visible channels, our model also exploits all information within infrared channels of the Meteosat 9 satellite. A genetic algorithm is used to optimize selection of model inputs, for which twelve are selected – eleven 3-km Meteosat 9 channels and one clear-sky term. The model is validated in Andalusia (Spain) from January 2008 through December 2008. Measured data from 83 stations across the region are used, 65 for training and 18 independent ones for testing the model. At the latter stations, the ensemble model yields an overall root mean square error of 6.74% and correlation coefficient of 99%; the generated estimates are relatively accurate and errors spatially uniform. The model yields reliable results even on cloudy days, improving on current models based on satellite imagery. - Highlights: • Daily solar radiation data are generated using an artificial neural network ensemble. • Eleven Meteosat channels observations and a clear sky term are used as model inputs. • Model exploits all information within infrared Meteosat channels. • Measured data for a year from 83 ground stations are used. • The proposed approach has better performance than existing models on daily basis

  10. Comparison of artificial intelligence methods and empirical equations to estimate daily solar radiation

    Science.gov (United States)

    Mehdizadeh, Saeid; Behmanesh, Javad; Khalili, Keivan

    2016-08-01

    In the present research, three artificial intelligence methods including Gene Expression Programming (GEP), Artificial Neural Networks (ANN) and Adaptive Neuro-Fuzzy Inference System (ANFIS) as well as, 48 empirical equations (10, 12 and 26 equations were temperature-based, sunshine-based and meteorological parameters-based, respectively) were used to estimate daily solar radiation in Kerman, Iran in the period of 1992-2009. To develop the GEP, ANN and ANFIS models, depending on the used empirical equations, various combinations of minimum air temperature, maximum air temperature, mean air temperature, extraterrestrial radiation, actual sunshine duration, maximum possible sunshine duration, sunshine duration ratio, relative humidity and precipitation were considered as inputs in the mentioned intelligent methods. To compare the accuracy of empirical equations and intelligent models, root mean square error (RMSE), mean absolute error (MAE), mean absolute relative error (MARE) and determination coefficient (R2) indices were used. The results showed that in general, sunshine-based and meteorological parameters-based scenarios in ANN and ANFIS models presented high accuracy than mentioned empirical equations. Moreover, the most accurate method in the studied region was ANN11 scenario with five inputs. The values of RMSE, MAE, MARE and R2 indices for the mentioned model were 1.850 MJ m-2 day-1, 1.184 MJ m-2 day-1, 9.58% and 0.935, respectively.

  11. Leptin deficiency-induced obesity exacerbates ultraviolet B radiation-induced cyclooxygenase-2 expression and cell survival signals in ultraviolet B-irradiated mouse skin

    International Nuclear Information System (INIS)

    Obesity has been implicated in several inflammatory diseases and in different types of cancer. Chronic inflammation induced by exposure to ultraviolet (UV) radiation has been implicated in various skin diseases, including melanoma and nonmelanoma skin cancers. As the relationship between obesity and susceptibility to UV radiation-caused inflammation is not clearly understood, we assessed the role of obesity on UVB-induced inflammation, and mediators of this inflammatory response, using the genetically obese (leptin-deficient) mouse model. Leptin-deficient obese (ob/ob) mice and wild-type counterparts (C57/BL6 mice) were exposed to UVB radiation (120 mJ/cm2) on alternate days for 1 month. The mice were then euthanized and skin samples collected for analysis of biomarkers of inflammatory responses using immunohistochemistry, western blotting, ELISA and real-time PCR. Here, we report that the levels of inflammatory responses were higher in the UVB-exposed skin of the ob/ob obese mice than those in the UVB-exposed skin of the wild-type non-obese mice. The levels of UVB-induced cyclooxygenase-2 expression, prostaglandin-E2 production, proinflammatory cytokines (i.e., tumor necrosis factor-α, interleukin-1β, interleukin-6), and proliferating cell nuclear antigen and cell survival signals (phosphatidylinositol-3-kinase and p-Akt-Ser473) were higher in the skin of the ob/ob obese mice than the those in skin of their wild-type non-obese counterparts. Compared with the wild-type non-obese mice, the leptin-deficient obese mice also exhibited greater activation of NF-κB/p65 and fewer apoptotic cells in the UVB-irradiated skin. Our study suggests for the first time that obesity in mice is associated with greater susceptibility to UVB-induced inflammatory responses and, therefore, obesity may increase susceptibility to UVB-induced inflammation-associated skin diseases, including the risk of skin cancer.

  12. Surface modification of polyurethane films by plasma and ultraviolet light to improve haemocompatibility for artificial heart valves.

    Science.gov (United States)

    Alves, P; Cardoso, R; Correia, T R; Antunes, B P; Correia, I J; Ferreira, P

    2014-01-01

    Prosthetic cardiac valves implantation is a common procedure used to treat heart valve diseases. Although there are different prostheses already available in the market (either mechanical or bioprosthetic), their use presents several problems, specifically concerning thrombogenicity and structural failure. Recently, some progresses have been achieved in developing heart valves based on synthetic materials with special emphasis in polymers. Among them, polyurethanes are one of the most commonly used for the production of these devices. Herein, Elastollan(®)1180A50, a thermoplastic polyurethane (TPU), was used to formulate films whose surfaces were modified by grafting 2-hydroxyethylmethacrylate (HEMA) either by ultra-violet (UV) or by plasma treatment. All films were analyzed before and after grafting. X-ray photoelectron spectroscopy (XPS) measurements were used to evaluate TPU surfaces functionalization. HEMA grafting was confirmed by the increase of the hydroxyl (OH) groups' concentration at the surface of the films. Atomic force microscopy (AFM) analysis was done to evaluate the surface topography of the biomaterials. Results showed that the roughness of the surface decreased when HEMA was grafted, especially for plasma treated samples. After grafting the films' hydrophilicity was improved, as well as the polar component of the surface energy, by 15-30%. Hydrophobic recovery studies using milli Q water or PBS were also performed to characterize the stability of the modified surface, showing that the films maintained their surface properties along time. Furthermore, blood-contact tests were performed to evaluate haemolytic and thrombogenic potential. The results obtained for HEMA grafted surfaces, using plasma treatment, confirmed biomaterials biocompatibility and low thrombogenicity. Finally, the cytotoxicity and antibacterial activity of the materials was assessed through in vitro assays for both modified films. The obtained results showed enhanced

  13. Photoreactivation of ICR 2A frog cells after exposure to monochromatic ultraviolet radiation in the 252-313 nm range

    International Nuclear Information System (INIS)

    Exposure of ICR 2A frog cells to photoreactivating light after treatment with monochromatic ultraviolet (UV) radiation in the 252-313nm range resulted in an increase in survival with similar photoreactivable sectors for each of the wavelengths tested. As photoreactivating enzyme is specific for the repair of pyrimidine dimers in DNA, these findings support the hypothesis that these are critical lesions responsible for killing of cells exposed to UV radiation in this wavelength range. The action spectra for cell killing and production of UV-endonuclease sensitive sites were similar to the DNA absorption spectrum though not identical. Because the number of endonuclease sensitive sites is a reflection of the yield of pyrimidine dimers, these data also suggest that the induction of dimers in DNA by UV radiation in the 252-313 nm range is the principle event leading to cell death. (author)

  14. Effects of solar ultraviolet radiation on the photochemical efficiency, photosynthetic pigments and biomass production of Spirulina platensis

    Institute of Scientific and Technical Information of China (English)

    WU Hongyan; GAO Kunshan; Teruo WATANABE

    2005-01-01

    Effects of solar ultraviolet radiation (UVR) on Spirulina platensis were studied by investigating its photochemical efficiency, photosynthetic pigments and biomass production while exposed to full spectrum solar radiation or depleted of UVR for understanding how and to what extent UVR influences its photosynthetic physiology and production. It was found that UVR brought about an extra inhibition of photochemical efficiency by 26 %-30 %. The greatest inhibition of photochemical efficiency in S. platensis was observed at noontime, and then recovered to some extent in late afternoon no matter which treatment they were exposed to. The contents of chlorophyll a, phycocyanin and carotenoids increased during initial stage of the exposure, but decreased with elongated exposure. UVR decreased the biomass yield by about 6 %. It indicated that filtering out UVR of solar radiation would raise the productivity of S. platensis,which is an important factor that should be considered in the production.

  15. Real time determination of dose radiation through artificial intelligence and virtual reality

    International Nuclear Information System (INIS)

    In the last years, a virtual environment of Argonauta research reactor, sited in the Instituto de Engenharia Nuclear (Brazil), has been developed. Such environment, called here Argonauta Virtual (AV), is a 3D model of the reactor hall, in which virtual people (avatar) can navigate. In AV, simulations of nuclear sources and doses are possible. In a recent work, a real time monitoring system (RTMS) was developed to provide (by means of Ethernet TCP/IP) the information of area detectors situated in the reactor hall. Extending the scope of AV, this work is intended to provide a continuous determination of gamma radiation dose in the reactor hall, based in several monitored parameters. To accomplish that a module based in artificial neural network (ANN) was developed. The ANN module is able to predict gamma radiation doses using as inputs: the avatar position (from virtual environment), the reactor power (from RTMS) and information of fixed area detectors (from RTMS). The ANN training data has been obtained by measurements of gamma radiation doses in a mesh of points, with previously defined positions, for different power levels. Through the use of ANN it is possible to estimate, in real time, the dose received by a person at any position in Argonauta reactor hall. Such approach allows tasks simulations and training of people inside the AV system, without exposing them to radiation effects. (author)

  16. SHORT-TERM SOLAR RADIATION FORECASTING BY USING AN ITERATIVE COMBINATION OF WAVELET ARTIFICIAL NEURAL NETWORKS

    Directory of Open Access Journals (Sweden)

    Julio Cesar Royer

    2016-03-01

    Full Text Available The information provided by accurate forecasts of solar energy time series are considered essential for performing an appropriate prediction of the electrical power that will be available in an electric system, as pointed out in Zhou et al. (2011. However, since the underlying data are highly non-stationary, it follows that to produce their accurate predictions is a very difficult assignment. In order to accomplish it, this paper proposes an iterative Combination of Wavelet Artificial Neural Networks (CWANN which is aimed to produce short-term solar radiation time series forecasting. Basically, the CWANN method can be split into three stages: at first one, a decomposition of level p, defined in terms of a wavelet basis, of a given solar radiation time series is performed, generating r+1 Wavelet Components (WC; at second one, these r+1 WCs are individually modeled by the k different ANNs, where k>5, and the 5 best forecasts of each WC are combined by means of another ANN, producing the combined forecasts of WC; and, at third one, the combined forecasts WC are simply added, generating the forecasts of the underlying solar radiation data. An iterative algorithm is proposed for iteratively searching for the optimal values for the CWANN parameters, as we will see. In order to evaluate it, ten real solar radiation time series of Brazilian system were modeled here. In all statistical results, the CWANN method has achieved remarkable greater forecasting performances when compared with a traditional ANN (described in Section 2.1.

  17. Cancer risk at low doses of ionizing radiation. Artificial neural networks inference from atomic bomb survivors

    International Nuclear Information System (INIS)

    Cancer risk at low doses of ionizing radiation remains poorly defined because of ambiguity in the quantitative link to doses below 0.2 Sv in atomic bomb survivors in Hiroshima and Nagasaki arising from limitations in the statistical power and information available on overall radiation dose. To deal with these difficulties, a novel nonparametric statistics based on the ‘integrate-and-fire’ algorithm of artificial neural networks was developed and tested in cancer databases established by the Radiation Effects Research Foundation. The analysis revealed unique features at low doses that could not be accounted for by nominal exposure dose, including (1) the presence of a threshold that varied with organ, gender and age at exposure, and (2) a small but significant bumping increase in cancer risk at low doses in Nagasaki that probably reflects internal exposure to 239Pu. The threshold was distinct from the canonical definition of zero effect in that it was manifested as negative excess relative risk, or suppression of background cancer rates. Such a unique tissue response at low doses of radiation exposure has been implicated in the context of the molecular basis of radiation–environment interplay in favor of recently emerging experimental evidence on DNA double-strand break repair pathway choice and its epigenetic memory by histone marking. (author)

  18. Real time determination of dose radiation through artificial intelligence and virtual reality

    International Nuclear Information System (INIS)

    In the last years, a virtual environment of Argonauta research reactor, sited in the Instituto de Engenharia Nuclear (Brazil), has been developed. Such environment, called here Argonauta Virtual (AV), is a 3D model of the reactor hall, in which virtual people (avatar) can navigate. In AV, simulations of nuclear sources and doses are possible. In a recent work, a real time monitoring system (RTMS) was developed to provide (by means of Ethernet TCP/I P) the information of area detectors situated in the reactor hall. Extending the scope of AV, this work is intended to provide a continuous determination of gamma radiation dose in the reactor hall, based in several monitored parameters. To accomplish that a module based in artificial neural network (ANN) was developed. The ANN module is able to predict gamma radiation doses using as inputs: the avatar position (from virtual environment), the reactor power (from RTMS) and information of fixed area detectors (from RTMS). The ANN training data has been obtained by measurements of gamma radiation doses in a mesh of points, with previously defined positions, for different power levels. Through the use of ANN it is possible to estimate, in real time, the dose received by a person at any position in Argonauta reactor hall. Such approach allows tasks simulations and training of people inside the AV system, without exposing them to radiation effects. (author)

  19. Prediction of monthly mean daily global solar radiation using Artificial Neural Network

    Indian Academy of Sciences (India)

    V Sivamadhavi; R Samuel Selvaraj

    2012-12-01

    In this study, a multilayer feed forward (MLFF) neural network based on back propagation algorithm was developed, trained, and tested to predict monthly mean daily global radiation in Tamil Nadu, India. Various geographical, solar and meteorological parameters of three different locations with diverse climatic conditions were used as input parameters. Out of 565 available data, 530 were used for training and the rest were used for testing the artificial neural network (ANN). A 3-layer and a 4-layer MLFF networks were developed and the performance of the developed models was evaluated based on mean bias error, mean absolute percentage error, root mean squared error and Student’s -test. The 3-layer MLFF network developed in this study did not give uniform results for the three chosen locations. Hence, a 4-layer MLFF network was developed and the average value of the mean absolute percentage error was found to be 5.47%. Values of global radiation obtained using the model were in excellent agreement with measured values. Results of this study show that the designed ANN model can be used to estimate monthly mean daily global radiation of any place in Tamil Nadu where measured global radiation data are not available.

  20. MC1R and the response of melanocytes to ultraviolet radiation

    Energy Technology Data Exchange (ETDEWEB)

    Rouzaud, Francois [Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Building 37, Room 2132, Bethesda, MD 20892 (United States); Kadekaro, Ana Luisa [Department of Dermatology, University of Cincinnati, College of Medicine, Cincinnati, OH 45267 (United States); Abdel-Malek, Zalfa A. [Department of Dermatology, University of Cincinnati, College of Medicine, Cincinnati, OH 45267 (United States); Hearing, Vincent J. [Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Building 37, Room 2132, Bethesda, MD 20892 (United States)]. E-mail: hearingv@nih.gov

    2005-04-01

    The constitutive color of our skin plays a dramatic role in our photoprotection from solar ultraviolet radiation (UVR) that reaches the Earth and in minimizing DNA damage that gives rise to skin cancer. More than 120 genes have been identified and shown to regulate pigmentation, one of the key genes being melanocortin 1 receptor (MC1R) that encodes the melanocortin 1 receptor (MC1R), a seven-transmembrane G protein-coupled receptor expressed on the surface of melanocytes. Modulation of MC1R function regulates melanin synthesis by melanocytes qualitatively and quantitatively. The MC1R is regulated by the physiological agonists {alpha}-melanocyte-stimulating hormone ({alpha}MSH) and adrenocorticotropic hormone (ACTH), and antagonist agouti signaling protein (ASP). Activation of the MC1R by binding of an agonist stimulates the synthesis of eumelanin primarily via activation of adenylate cyclase. The significance of cutaneous pigmentation lies in the photoprotective effect of melanin, particularly eumelanin, against sun-induced carcinogenesis. Epidermal melanocytes and keratinocytes respond to UVR by increasing their expression of {alpha}MSH and ACTH, which up-regulate the expression of MC1R, and consequently enhance the response of melanocytes to melanocortins. Constitutive skin pigmentation dramatically affects the incidence of skin cancer. The pigmentary phenotype characterized by red hair, fair complexion, inability to tan and tendency to freckle is an independent risk factor for all skin cancers, including melanoma. The MC1R gene is highly polymorphic in human populations, and allelic variation at this locus accounts, to a large extent, for the variation in pigmentary phenotypes and skin phototypes (SPT) in humans. Several allelic variants of the MC1R gene are associated with the red hair and fair skin (RHC) phenotype, and carrying one of these variants is thought to diminish the ability of the epidermis to respond to DNA damage elicited by UVR. The MC1R gene is