[UV-radiation--sources, wavelength, environment].

PubMed

Hölzle, Erhard; Hönigsmann, Herbert

2005-09-01

The UV-radiation in our environment is part of the electromagnetic radiation, which emanates from the sun. It is designated as optical radiation and reaches from 290-4,000 nm on the earth's surface. According to international definitions UV irradiation is divided into short-wave UVC (200-280 nm), medium-wave UVB (280-320 nm), and long-wave UVA (320-400 nm). Solar radiation which reaches the surface of the globe at a defined geographical site and a defined time point is called global radiation. It is modified quantitatively and qualitatively while penetrating the atmosphere. Besides atmospheric conditions, like ozone layer and air pollution, geographic latitude, elevation, time of the season, time of the day, cloudiness and the influence of indirect radiation resulting from stray effects in the atmosphere and reflection from the underground play a role in modifying global radiation, which finally represents the biologically effective radiation. The radiation's distribution on the body surface varies according to sun angle and body posture. The cumulative UV exposure is mainly influenced by outdoor profession and recreational activities. The use of sun beds and phototherapeutic measures additionally may contribute to the cumulative UV dose.

Wavefront propagation simulations for a UV/soft x-ray beamline: Electron Spectro-Microscopy beamline at NSLS-II

NASA Astrophysics Data System (ADS)

Canestrari, N.; Bisogni, V.; Walter, A.; Zhu, Y.; Dvorak, J.; Vescovo, E.; Chubar, O.

2014-09-01

A "source-to-sample" wavefront propagation analysis of the Electron Spectro-Microscopy (ESM) UV / soft X-ray beamline, which is under construction at the National Synchrotron Light Source II (NSLS-II) in the Brookhaven National Laboratory, has been conducted. All elements of the beamline - insertion device, mirrors, variable-line-spacing gratings and slits - are included in the simulations. Radiation intensity distributions at the sample position are displayed for representative photon energies in the UV range (20 - 100 eV) where diffraction effects are strong. The finite acceptance of the refocusing mirrors is the dominating factor limiting the spatial resolution at the sample (by ~3 μm at 20 eV). Absolute estimates of the radiation flux and energy resolution at the sample are also obtained from the electromagnetic calculations. The analysis of the propagated UV range undulator radiation at different deflection parameter values demonstrates that within the beamline angular acceptance a slightly "red-shifted" radiation provides higher flux at the sample and better energy resolution compared to the on-axis resonant radiation of the fundamental harmonic.

Atmospheric scattering of middle uv radiation from an internal source.

PubMed

Meier, R R; Lee, J S; Anderson, D E

1978-10-15

A Monte Carlo model has been developed which simulates the multiple-scattering of middle-uv radiation in the lower atmosphere. The source of radiation is assumed to be monochromatic and located at a point. The physical effects taken into account in the model are Rayleigh and Mie scattering, pure absorption by particulates and trace atmospheric gases, and ground albedo. The model output consists of the multiply scattered radiance as a function of look-angle of a detector located within the atmosphere. Several examples are discussed, and comparisons are made with direct-source and single-scattered contributions to the signal received by the detector.

Ultraviolet light propagation under low visibility atmospheric conditions and its application to aircraft landing aid.

PubMed

Lavigne, Claire; Durand, Gérard; Roblin, Antoine

2006-12-20

Light scattering in the atmosphere by particles and molecules gives rise to an aureole surrounding the source image that tends to reduce the contrast of the source with respect to the background. However, UV scattering phase functions of the haze droplets present a very important forward peak. The spreading of a detected signal in the UV is not as important as in the case of a clear atmosphere where Rayleigh scattering predominates. This physical property has to be taken into account to evaluate the potential of UV radiation as an aircraft landing aid under low visibility conditions. Different results characterizing UV runway lights, simulations of UV radiation propagation in the atmosphere, and the use of a simple detection algorithm applied to one particular sensor are presented.

VUV lithography

DOEpatents

George, E.V.; Oster, Y.; Mundinger, D.C.

1990-12-25

Deep UV projection lithography can be performed using an e-beam pumped solid excimer UV source, a mask, and a UV reduction camera. The UV source produces deep UV radiation in the range 1,700--1,300A using xenon, krypton or argon; shorter wavelengths of 850--650A can be obtained using neon or helium. A thin solid layer of the gas is formed on a cryogenically cooled plate and bombarded with an e-beam to cause fluorescence. The UV reduction camera utilizes multilayer mirrors having high reflectivity at the UV wavelength and images the mask onto a resist coated substrate at a preselected demagnification. The mask can be formed integrally with the source as an emitting mask. 6 figs.

UV radiation, vitamin D, and cancer: how to measure the vitamin D synthetic capacity of UV sources?

NASA Astrophysics Data System (ADS)

Terenetskaya, Irina; Orlova, Tatiana

2005-09-01

UV irradiation is widely used in phototherapy. Regardless of the fact that UV overexposure is liable to cause adverse health effect, in appropriate doses UV radiation initiates synthesis of vitamin D in skin that is absolutely essential for human health. As it proved, most people in northern industrial countries have a level of vitamin D in their bodies that is insufficient for optimum health, especially in winter. These low levels of vitamin D are now known to be associated with a wide spectrum of serious disease much of which leads on to premature death. The diseases associated with D deficiency involve more than a dozen types of cancer including colon, breast and prostate, as well as the classic bone diseases: rickets, osteoporosis and osteomalacia. Irradiation with artificial UV sources can prevent the vitamin D deficiency. However, in view of different irradiation spectra of UV lamps, their ability to initiate vitamin D synthesis is different. The reliable method based on an in vitro model of vitamin D synthesis has been developed for direct measurement in situ of the vitamin D synthetic capacity of artificial UV sources during a phototherapeutic procedure

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

NASA Astrophysics Data System (ADS)

Gulati, P.; Prakash, R.; Pal, U. N.; Kumar, M.; Vyas, V.

2014-07-01

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gulati, P., E-mail: pgulati1512@gmail.com; Department of Physics, Banasthali University, P.O. Banasthali Vidyapith, Rajasthan 304022; Prakash, R.

2014-07-07

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 Cl{sub 2} deteriorates the performance of the developed source and around 2% Cl{sub 2} in this source produced optimum results. Furthermore, anmore » 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.« less

DNA damage and repair in plants under ultraviolet and ionizing radiations.

PubMed

Gill, Sarvajeet S; Anjum, Naser A; Gill, Ritu; Jha, Manoranjan; Tuteja, Narendra

2015-01-01

Being sessile, plants are continuously exposed to DNA-damaging agents present in the environment such as ultraviolet (UV) and ionizing radiations (IR). Sunlight acts as an energy source for photosynthetic plants; hence, avoidance of UV radiations (namely, UV-A, 315-400 nm; UV-B, 280-315 nm; and UV-C, <280 nm) is unpreventable. DNA in particular strongly absorbs UV-B; therefore, it is the most important target for UV-B induced damage. On the other hand, IR causes water radiolysis, which generates highly reactive hydroxyl radicals (OH(•)) and causes radiogenic damage to important cellular components. However, to maintain genomic integrity under UV/IR exposure, plants make use of several DNA repair mechanisms. In the light of recent breakthrough, the current minireview (a) introduces UV/IR and overviews UV/IR-mediated DNA damage products and (b) critically discusses the biochemistry and genetics of major pathways responsible for the repair of UV/IR-accrued DNA damage. The outcome of the discussion may be helpful in devising future research in the current context.

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

PubMed

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

2015-05-01

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

Genotoxicity and carcinogenicity of the light emitted by artificial illumination systems.

PubMed

De Flora, Silvio

2013-03-01

The light delivered by artificial illumination systems, and in particular by halogen quartz bulbs, contains UVA, UVB, and UVC radiation, is genotoxic to both bacterial and human cells and is potently carcinogenic to hairless mice. Since IARC has classified UV radiation in Group 1, any source of UV light poses a carcinogenic hazard to humans. Suitable regulations would be needed in order to control the safety of the light emitted by artificial light sources.

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

PubMed

Kheyrandish, Ataollah; Mohseni, Madjid; Taghipour, Fariborz

2018-06-15

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

Ultraviolet laser effects on the cornea

NASA Astrophysics Data System (ADS)

Zuclich, Joseph A.

1990-07-01

Ultraviolet radiation in the ambient environment or from artificial sources may pose both acute and chronic hazards to the skin and the ocular tissues. In general terrestrial conditions have evolved such that there are only narrow safety margins between ambient UV levels and exposure levels harmful to the human. Obvious examples of acute consequences ofUV overexposure are sunburn and snowblindness as well as analogous conditions induced by artificial sources such as the welder''s arc mercury vapor lamps and UV-emitting lasers. Further chronic UV exposure is strongly implicated as a causative agent in certain types of cataract and skin cancer. This presentation will summarize a number of specific cases where UV radiation affected the primate cornea. Data presented will include the action spectra for far- and near-UV induced ocular damage the pulsewidth and total energy dependencies of ocular thresholds studies of cumulative effects of repeated UV exposures and quantitative determinations of tissue repair or recovery rates. Depending on the exposure parameters utilized photochemical thermal or photoablative damage mechanisms may prevail. 1.

Radiation damage of all-silica fibers in the UV region

NASA Astrophysics Data System (ADS)

Gombert, Joerg; Ziegler, M.; Assmus, J.; Klein, Karl-Friedrich; Nelson, Gary W.; Clarkin, James P.; Pross, H.; Kiefer, J.

1999-04-01

Since several years, UVI-fibers having higher solarization- resistance are well known stimulating new fiber-optic applications in the UV-region below 250 nm. Besides the description of the improved transmission properties of UV- light from different UV-sources, the mechanisms of improvement have been discussed in detail. The UV-defects, mainly the E'- center with the UV-absorption band around 215 nm, were passivated by using hydrogen-doping. Besides DUV-light, ionizing radiation like Gamma-radiation or X-rays can create similar defects in the UV-region. In the past, the radiation- damage in the UV-region was studied on silica bulk samples: again, E'-centers were generated. Up to now, no UV- transmission through a 1 m long fiber during or after Gamma- radiation had been observed. However, the hydrogen in the UVI- fibers behaves the same for Gamma-irradiation, leading to a passivation of the radiation-induced defects and an improved transmission in the UV-C region below 250 nm. On this report, the influence of total dose and fiber diameter on the UV- damage after irradiation will be described and discussed. In addition, we will include annealing studies, with and without UV-light. Based on our results, the standard process of Gamma- sterilization with a total dose of approx. 2 Mrad can be used for UVI-fibers resulting in a good UV-transmission below 320 nm. Excimer-laser light at 308 nm (XeCl) and 248 nm (KrF) and deuterium-lamp light with the full spectrum starting at 200 nm can also be transmitted.

Are current guidelines for sun protection optimal for health? Exploring the evidence.

PubMed

Lucas, Robyn M; Neale, Rachel E; Madronich, Sasha; McKenzie, Richard L

2018-06-15

Exposure of the skin to ultraviolet (UV) radiation is the main risk factor for skin cancer, and a major source of vitamin D, in many regions of the world. Sun protection messages to minimize skin cancer risks but avoid vitamin D deficiency are challenging, partly because levels of UV radiation vary by location, season, time of day, and atmospheric conditions. The UV Index provides information on levels of UV radiation and is a cornerstone of sun protection guidelines. Current guidelines from the World Health Organization are that sun protection is required only when the UV Index is 3 or greater. This advice is pragmatic rather than evidence based. The UV Index is a continuous scale; more comprehensive sun protection is required as the UV Index increases. In addition, a wide range of UVA doses is possible with a UVI of 3, from which there may be health consequences, while full sun protection when the UVI is "moderate" (between 3 and 5) may limit vitamin D production. Finally, the duration of time spent in the sun is an essential component of a public health message, in addition to the intensity of ambient UV radiation as measured by the UV Index. Together these provide the dose of UV radiation that is relevant to both skin cancer genesis and vitamin D production. Further education is required to increase the understanding of the UV Index; messages framed using the UV Index need to incorporate the importance of duration of exposure and increasing sun protection with increasing dose of UV radiation.

The mechanisms of protection of antioxidants on Nostoc sphaeroides against UV-B radiation

NASA Astrophysics Data System (ADS)

Wang, G. H.

UV radiation is one of space harmful factor for earth organisms in space exploration In the present work we studied on the role of antioxidant system in Nostoc sphaeroides K u tz Cyanobacteria and the effects of exogenous antioxidant molecules on its photosynthetic rate under UV-B radiation It was found that UV-B radiation decreased the photosynthetic activity of cyanobacterium but promoted the activity of antioxidant system to protect photosystem II PSII and exogenous antioxidant sodium nitroprusside SNP N-acetylcysteine NAC had an obvious protection on PSII activity under UV-B radiation The activity of SOD Superoxide Dismutase EC 1 15 1 1 CAT Catalase EC 1 11 1 6 POD Peroxidase EC 1 11 1 7 and content of MDA and ASC were improved by 0 5mM and 1mM SNP but 0 1mM SNP decreased the activity of antioxide system Exogenous NAC addition decreased the activity of SOD POD CAT and the content MDA and ASC but exogenous NAC addition increased the content of GSH The results suggested that exogenous SNP and NAC may protect algae by different mechanisms in which SNP maybe play double roles as sources of reactive free radicals or ROS scavengers in formation of algae s protection of PSII under UV-B radiation while NAC does function as antioxidant reagent or precursor of glutathione which could protect PSII directly from UV-B radiation Keyword antioxidant system exogenous or endogenous antioxidant Nostoc sphaeroides photosynthesis UV-B radiation

UV emissions from low energy artificial light sources.

PubMed

Fenton, Leona; Moseley, Harry

2014-01-01

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

DNA Damage and Repair in Plants under Ultraviolet and Ionizing Radiations

PubMed Central

Gill, Sarvajeet S.; Gill, Ritu; Jha, Manoranjan; Tuteja, Narendra

2015-01-01

Being sessile, plants are continuously exposed to DNA-damaging agents present in the environment such as ultraviolet (UV) and ionizing radiations (IR). Sunlight acts as an energy source for photosynthetic plants; hence, avoidance of UV radiations (namely, UV-A, 315–400 nm; UV-B, 280–315 nm; and UV-C, <280 nm) is unpreventable. DNA in particular strongly absorbs UV-B; therefore, it is the most important target for UV-B induced damage. On the other hand, IR causes water radiolysis, which generates highly reactive hydroxyl radicals (OH•) and causes radiogenic damage to important cellular components. However, to maintain genomic integrity under UV/IR exposure, plants make use of several DNA repair mechanisms. In the light of recent breakthrough, the current minireview (a) introduces UV/IR and overviews UV/IR-mediated DNA damage products and (b) critically discusses the biochemistry and genetics of major pathways responsible for the repair of UV/IR-accrued DNA damage. The outcome of the discussion may be helpful in devising future research in the current context. PMID:25729769

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

NASA Astrophysics Data System (ADS)

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

2015-12-01

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

[Effect of ultraviolet radiation on ALDH1 expression in human lens epithelial cells].

PubMed

Shi, Jingming; Jia, Songbai; Chen, Xuan; Tang, Luosheng

2012-06-01

To determine the apoptosis-inducing effect of ultraviolet light (UV) on human lens epithelial cell (HLEC) and to explore the involvement of changes in ALDH1 folowing UV radiation. HLEC was exposed to the same UV light source and was subsequently divided into 6 groups according to UV radiation time of 0 (control group), 5, 10, 15, and 30 min. Apoptosis was detected by AO/EB staining. Changes of ALDH1 in HLEC were detected by immunohistochemical staining and Western blot. The intensity of immunohistochemical staining and the rate of positive cells decreased with increase of UV time (P<0.05). The rate of positive ALDH1 cells was negatively correlated with the rate of apoptosis (r= -0.92, P<0.05). Western blot showed the integrated absorbance values significantly decreased with the increase of UV time (P<0.05). ALDH1 in HLEC decreases with an increase of UV exposure, which may be related to UV induced apoptosis of HLEC.

Effect of enhanced UV-B radiation on pollen quantity, quality, and seed yield in Brassica rapa (Brassicaceae)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Demchik, S.M.; Day, T.A.

Three experiments examined the influence of ultraviolet-B radiation (UV-B; 280-320 nm) exposure on reproduction in Brassica rapa (Brassicacaeae). Plants were grown in a greenhouse under three biologically effective UV-B levels that stimulated either an ambient stratospheric ozone level (control), 16% ({open_quotes}low enhanced{close_quotes}), or 32% ({open_quotes}high enhanced{close_quotes}) ozone depletion levels at Morgantown, WV, USA in mid-March. In the first experiment,pollen production and viability per flower were reduced by {approx}50% under both enhanced UV-B levels relative to ambient controls. While plants under high-enhanced UV-B produced over 40% more flowers than plants under the two lower UV-B treatments, whole-plant production of viable pollenmore » was reduced under low-enhanced UV-B to 34% of ambient controls. In the second experiment, the influence of source-plant UV-B exposure on in vitro pollen from plants was examined and whether source-plant UV-B exposure influenced in vitro pollen germination and viability. Pollen from plants under both enhanced-UV-B was reduced from 65 to 18%. Viability of the pollen from plants grown under both enhanced UV-B treatments was reduced to a much lesser extent: only from {approx}43 to 22%. Thus, ambient source-plant pollen was more sensitive to enhanced UV-B levels to fertilize plants growing under ambient-UV-B levels, and assessed subsequent seed production and germination. Seed abortion rates were higher in plants pollinated with pollen from the enhanced UV-B treatments, than from ambient UV-B. Despite this, seed yield (number and mass) per plant was similar, regardless of the UV-B exposure of their pollen source. Our findings demonstrate that enhanced UV-B levels associated with springtime ozone depletion events have the capacity to substantially reduce viable pollen production, and could ultimately reduce reproductive success of B. rapa. 37 refs., 4 figs., 2 tabs.« less

Laser discrimination by stimulated emission of a phosphor

NASA Technical Reports Server (NTRS)

Mathur, V. K.; Chakrabarti, K.

1991-01-01

A method for discriminating sources of UV, near infrared, and far infrared laser radiation was discovered. This technology is based on the use of a single magnesium sulfide phosphor doubly doped with rare earth ions, which is thermally/optically stimulated to generate colors correlatable to the incident laser radiation. The phosphor, after initial charging by visible light, exhibits green stimulated luminescence when exposed to a near infrared source (Nd: YAG laser). On exposure to far infrared sources (CO2 laser) the phosphor emission changes to orange color. A UV laser produces both an orange red as well as green color. A device using this phosphor is useful for detecting the laser and for discriminating between the near infrared, far infrared, and UV lasers. The technology is also capable of infrared laser diode beam profiling since the radiation source leaves an imprint on the phosphor that can be photographed. Continued development of the technology offers potential for discrimination between even smaller bandwidths within the infrared spectrum, a possible aid to communication or wavemixing devices that need to rapidly identify and process optical signals.

Towards a high performing UV-A sensor based on Silicon Carbide and hydrogenated Silicon Nitride absorbing layers

NASA Astrophysics Data System (ADS)

Mazzillo, M.; Sciuto, A.; Mannino, G.; Renna, L.; Costa, N.; Badalà, P.

2016-10-01

Exposure to ultraviolet (UV) radiation is a major risk factor for most skin cancers. The sun is our primary natural source of UV radiation. The strength of the sun's ultraviolet radiation is expressed as Solar UV Index (UVI). UV-A (320-400 nm) and UV-B (290-320 nm) rays mostly contribute to UVI. UV-B is typically the most destructive form of UV radiation because it has enough energy to cause photochemical damage to cellular DNA. Also overexposure to UV-A rays, although these are less energetic than UV-B photons, has been associated with toughening of the skin, suppression of the immune system, and cataract formation. The use of preventive measures to decrease sunlight UV radiation absorption is fundamental to reduce acute and irreversible health diseases to skin, eyes and immune system. In this perspective UV sensors able to monitor in a monolithic and compact chip the UV Index and relative UV-A and UV-B components of solar spectrum can play a relevant role for prevention, especially in view of the integration of these detectors in close at hand portable devices. Here we present the preliminary results obtained on our UV-A sensor technology based on the use of hydrogenated Silicon Nitride (SiN:H) thin passivating layers deposited on the surface of thin continuous metal film Ni2Si/4H-SiC Schottky detectors, already used for UV-Index monitoring. The first UV-A detector prototypes exhibit a very low leakage current density of about 0.2 pA/mm2 and a peak responsivity value of 0.027 A/W at 330 nm, both measured at 0V bias.

Effect of UV-B Radiation and Desiccation Stress on Photoprotective Compounds Accumulation in Marine Leptolyngbya sp.

PubMed

Joshi, Devika; Mohandass, C; Dhale, Mohan

2018-01-01

Increased awareness regarding the harmful effects of ultraviolet (UV)-B radiation has led to the search for new sources of natural UV-B protecting compounds. Mycosporine-like amino acids are one of such promising compounds found in several organisms. Cyanobacteria are ideal organisms for isolation of these compounds due to their compatibility and adaptability to thrive under harsh environmental conditions. In the following investigation, we report the production of shinorine in Leptolyngbya sp. isolated from the intertidal region. Based on the spectral characteristics and liquid chromatography-mass spectrometry analysis, the UV-absorbing compound was identified as shinorine. To the best of our knowledge, this is the first report on the occurrence of shinorine in Leptolyngbya sp. We also investigated the effect of artificial UV-B radiation and periodic desiccation on chlorophyll-a, total carotenoids, and mycosporine-like amino acids (MAAs) production. The UV-B radiation had a negative effect on growth and chlorophyll concentration, whereas it showed an inductive effect on the production of total carotenoids and MAAs. Desiccation along with UV-B radiation led to an increase in the concentration of photoprotective compounds. These results indicate that carotenoids and MAAs thus facilitate cyanobacteria to avoid and protect themselves from the deleterious effects of UV-B and desiccation.

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

NASA Astrophysics Data System (ADS)

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

2009-02-01

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

All-periodically poled, high-power, continuous-wave, single-frequency tunable UV source.

PubMed

Aadhi, A; Chaitanya N, Apurv; Jabir, M V; Singh, R P; Samanta, G K

2015-01-01

We report on experimental demonstration of an all-periodically poled, continuous-wave (CW), high-power, single-frequency, ultra-violet (UV) source. Based on internal second-harmonic-generation (SHG) of a CW singly resonant optical parametric oscillator (OPO) pumped in the green, the UV source provides tunable radiation across 398.94-417.08 nm. The compact source comprising of a 25-mm-long MgO-doped periodically poled stoichiometric lithium tantalate (MgO:sPPLT) crystal of period Λ(SLT)=8.5  μm for OPO and a 5-mm-long, multi-grating (Λ(KTP)=3.3, 3.4, 3.6 and 3.8 μm), periodically poled potassium titanium phosphate (PPKTP) for intra-cavity SHG, provides as much as 336 mW of UV power at 398.94 nm, corresponding to a green-to-UV conversion efficiency of ∼6.7%. In addition, the singly resonant OPO (SRO) provides 840 mW of idler at 1541.61 nm and substantial signal power of 108 mW at 812.33 nm transmitted through the high reflective cavity mirrors. UV source provides single-frequency radiation with instantaneous line-width of ∼18.3  MHz and power >100  mW in Gaussian beam profile (ellipticity >92%) across the entire tuning range. Access to lower UV wavelengths requires smaller grating periods to compensate high phase-mismatch resulting from high material dispersion in the UV wavelength range. Additionally, we have measured the normalized temperature and spectral acceptance bandwidth of PPKTP crystal in the UV wavelength range to be ∼2.25°C·cm and ∼0.15  nm·cm, respectively.

Effects of ultraviolet radiation on photosynthetic performance and N2 fixation in Trichodesmium erythraeum IMS 101

NASA Astrophysics Data System (ADS)

Cai, Xiaoni; Hutchins, David A.; Fu, Feixue; Gao, Kunshan

2017-10-01

Biological effects of ultraviolet radiation (UVR; 280-400 nm) on marine primary producers are of general concern, as oceanic carbon fixers that contribute to the marine biological CO2 pump are being exposed to increasing UV irradiance due to global change and ozone depletion. We investigated the effects of UV-B (280-320 nm) and UV-A (320-400 nm) on the biogeochemically critical filamentous marine N2-fixing cyanobacterium Trichodesmium (strain IMS101) using a solar simulator as well as under natural solar radiation. Short exposure to UV-B, UV-A, or integrated total UVR significantly reduced the effective quantum yield of photosystem II (PSII) and photosynthetic carbon and N2 fixation rates. Cells acclimated to low light were more sensitive to UV exposure compared to high-light-grown ones, which had more UV-absorbing compounds, most likely mycosporine-like amino acids (MAAs). After acclimation under natural sunlight, the specific growth rate was lower (by up to 44 %), MAA content was higher, and average trichome length was shorter (by up to 22 %) in the full spectrum of solar radiation with UVR, than under a photosynthetically active radiation (PAR) alone treatment (400-700 nm). These results suggest that prior shipboard experiments in UV-opaque containers may have substantially overestimated in situ nitrogen fixation rates by Trichodesmium, and that natural and anthropogenic elevation of UV radiation intensity could significantly inhibit this vital source of new nitrogen to the current and future oligotrophic oceans.

The strong UV source in the active E Galaxy NGC 4552

NASA Technical Reports Server (NTRS)

Oconnell, R. W.; Thuan, T. X.; Puschell, J. J.

1986-01-01

1200-3200 A IUE spectra of the nucleus of NGC 4552 (M89) were obtained in order to investigate the nature of the strong 10 micron source in this Galaxy. There is a strong, extended UV source in NGC 4552 which has a spatial distribution nearly identical with that at optical wavelengths and is undoubedly stellar in origin. Its properties are consistent with the correlation between UV source strength and metallicity pointed out by Faber (1983). There is no evidence for a nonthermal point source in the UV. It appears unlikely that the 10 micron emission is from heated dust grains. Instead, it is believed the 10 micron radiation is nonthermal in origin, implying a remarkably small size of only 0.1 AU for this source.

Preparation and Characterization of UV Emitting Fluoride Phosphors for Phototherapy Lamps

NASA Astrophysics Data System (ADS)

Belsare, P. D.; Moharil, S. V.; Joshi, C. P.; Omanwar, S. K.

2011-10-01

The use of ultraviolet radiation for the treatment of various skin diseases is well known for long time. Phototherapy employs ultraviolet-blue radiation to cure skin diseases. The basis of phototherapy is believed to be the direct interaction of light of certain frequencies with tissue to cause a change in immune response. Currently dermatologists use UV lamps having specific emissions in UV region for treating various skin diseases. The treatment of skin diseases using artificial sources of UV radiation is now well established and more than 50 types of skin diseases are treated by phototherapy. This is an effective treatment for many skin disorders, such as psoriasis, vitiligo, ofujis disease, morphea , scleroderma, cutaneous T-cell lymphoma, lupus erythematosus, hyperbilirubinemia commonly known as infant jaundice, acne vulgaris, This paper reports photoluminescence properties of UV emitting fluoride phosphors prepared by wet chemical method. Emission characteristics of these phosphors are found similar to those of commercial UV lamp phosphors with comparable intensities. The usefulness of UV emitting fluoride phosphor is discussed in the paper.

A proposal for in vitro/GFR molecular erythema action spectrum

NASA Astrophysics Data System (ADS)

de Souza, João A. V.; Lorenzini, Fabiane; Rizzatti, Mara R.

2008-08-01

We propose an erythema action spectrum based on experimental molecular measurements named molecular erythema action spectrum or in vitro/GFR, where the acronym GFR represents our research group name, Grupo de Física das Radiaçöes. The in vitro methodology was developed by using a derma tissue simulator (TSD), as a radiation protection shield, and monochromatic ultraviolet (UV) sources of 254, 310, 365, 380, and 400 nm. The irradiance from each source was monitored through spectroradiometry in order to obtain the exposure dose over a period of time. Changes in the chemical structure were monitored by Fourier transform infrared spectroscopy (FTIR) and UV and visible spectroscopy (UV-vis). The samples were analyzed by UV-vis at each 200 up to 1000 J/m2 and at each 400 up to 2000 J/m2. FTIR was performed only for samples exposed to a maximum dose of 2000 J/m2. The in vitro action parameters were obtained by considering the redshift revealed through UV-vis analysis, as being the molecular quantification of minimal erythema, and the chemical bond rupture of TSD molecules associated with erythema, revealed through FTIR. The in vitro/GFR action spectrum shows that UV-A and UV-B radiation are equally responsible for the damage observed in TSD. When this proposal was compared to the CIE erythema action spectrum from ISO [ISO17166 CIE S 007/E, Erythema Reference Action Spectrum and Standard Erythema Dose (CIE Central Bureau, Austria, 1998)], similarities could be observed in wavelengths less than 280 nm in UV-B region. However, for wavelengths higher than 300 nm, the efficiency of this radiation to induce damage, mainly in the UV-A part, was much higher than predicted in CIE model. The increasing concern on UV-A radiation, assumed to be as responsible as UV-B for inducing most of the already observed skin injuries, may be better understood when observing the experimental model presented in in vitro/GFR action spectrum.

Effects of ultraviolet radiation on 25-hydroxyvitamin D3 synthesis in red-eared slider turtles (Trachemys scripta elegans).

PubMed

Acierno, Mark J; Mitchell, Mark A; Roundtree, Marlana K; Zachariah, Trevor T

2006-12-01

To determine whether there are increased concentrations of 25-hydroxyvitaminn D(3) in red-eared slider turtles (Trachemys scripta elegans) after exposure to UV radiation. 12 yearling turtles recently removed from aestivation. Turtles were randomly allocated to 2 groups (6 turtles/group). An initial blood sample was collected from all turtles for measurement of 25-hydroxyvitamin D(3) concentrations. Turtles of 1 group were then provided no supplemental lighting, whereas turtles of the other group were exposed to full-spectrum coil bulbs at a distance of 22.86 cm. The UV-A and UV-B radiation generated by the supplemental lighting was measured by use of a radiometer-photometer at weekly intervals. Measurements were collected 2.54 and 22.86 cm from the bulb surface. The study was continued for a 4-week period. At the end of the study, a second blood sample was collected from all turtles for measurement of 25-hydroxyvitamin D(3). Mean +/- SD 25-hydroxyvitamin D(3) concentrations differed significantly between turtles provided supplemental UV radiation (71.7 +/- 46.9 nmol/L) and those not provided UV radiation (31.4 +/- 13.2 nmol/L). Appropriate husbandry recommendations for raising and maintaining red-eared slider turtles should include use of sunlight that is unobstructed by UV-B filtering material or provision of an artificial source of UV-B radiation.

(E)-5-[2-(methoxycarbonyl)ethenyl]cytidine as a chemical actinometer for germicidal UV radiation.

PubMed

Shen, Chengyue; Fang, Shiyue; Bergstrom, Donald E; Blatchley, Ernest R

2005-05-15

(E)-5-[2-(Methoxycarbonyl)ethenyl]cytidine (S) was examined for use as a chemical actinometer for germicidal UV radiation. Its photoproduct, 3-beta-D-ribofuranosyl-2,7-dioxopyrido[2,3-d]pyrimidine (P), is strongly fluorescent with excitation and emission maxima at 330 and 385 nm, respectively. Experiments were conducted to characterize the dynamic behavior of aqueous solutions of S and P when subjected to UV radiation. UV sources used for these experiments included a low-pressure mercury lamp, a XeBr excimer lamp, and a KrCI excimer lamp; all three sources were mounted in collimating devices to provide incident beams that could be easily and accurately characterized by radiometry. These three sources each yielded essentially monochromatic outputwith characteristic wavelengths of 254, 282, and 222 nm, respectively. At practical concentrations, it was found that the absorbance of the actinometer solution was neither high enough to make the actinometer solutions optically opaque nor low enough to be optically transparent to UV. In addition, the photoproduct displayed a molar absorption coefficient that was similar in magnitude to that of the parent compound, thereby resulting in competitive absorption of UV energy between Sand Pduring irradiation. For purposes of evaluation of the results of irradiation, a mathematical model was developed to accountforthe nonideal optical characteristics of the system. The model is based on a description of local photochemical kinetics; predictions of overall reactor performance were developed by spatial and temporal integration of model results. The model was used to analyze the dynamic behavior of actinometer solutions during UV irradiation and to estimate the quantum yield for photoproduction of Pfrom S. This modeling approach is potentially applicable to other photochemical processes in which multiple compounds are present that absorb photoactive radiation; however, general application of this modeling approach to photochemical reactor systems will require inclusion of othertermsto describe relevanttransport behavior within the system.

SPATIAL AND TEMPORAL VARIABILITY IN THE AMOUNT AND SOURCE OF DISSOLVED ORGANIC CARBON: IMPLICATIONS FOR UV EXPOSURE IN AMPHIBIAN HABITATS

EPA Science Inventory

The amount, chemical composition, and source of dissolved organic carbon (DOC), together with in situ ultraviolet-B radiation (UV -B; 280 to 320 nm) attenuation, were measured at one to two week intervals throughout the summers of 1999,2000, and 2001 at four sites in Rocky Mounta...

The response of antioxidant systems in Nostoc sphaeroides against UV-B radiation and the protective effects of exogenous antioxidants

NASA Astrophysics Data System (ADS)

Wang, Gaohong; Hu, Chunxiang; Li, Dunhai; Zhang, Delu; Li, Xiaoyan; Chen, Kun; Liu, Yongding

UV radiation is one of many harmful factors found in space that are detrimental to organisms on earth in space exploration. In the present work, we examined the role of antioxidant system in Nostoc sphaeroides Kütz (Cyanobacterium) and the effects of exogenously applied antioxidant molecules on its photosynthetic rate under UV-B radiation. It was found that UV-B radiation promoted the activity of antioxidant system to protect photosystem II (PSII) and exogenously applied antioxidant: sodium nitroprusside (SNP) and N-acetylcysteine (NAC) had an obvious protection on PSII activity under UV-B radiation. The activity of superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), peroxidase (POD, EC 1.11.1.7) and content of MDA (malondialdehyde) and ASC (ascorbate) were improved by 0.5 mM and 1 mM SNP, but 0.1 mM SNP decreased the activity of antioxidant system. Addition of exogenous NAC decreased the activity of SOD, POD, CAT and the content MDA and ASC. In contrast, exogenously applied NAC increased GSH content. The results suggest that exogenous SNP and NAC may protect algae by different mechanisms: SNP may play double roles as both sources of reactive free radicals as well as ROS scavengers in mediating the protective role of PSII on algae under UV-B radiation. On the other hand, NAC functions as an antioxidant or precursor of glutathione, which could protect PSII directly from UV-B radiation.

Impact of shortwave ultraviolet (UV-C) radiation on the antioxidant activity of thyme (Thymus vulgaris L.).

PubMed

Dogu-Baykut, Esra; Gunes, Gurbuz; Decker, Eric Andrew

2014-08-15

Thyme is a good source of antioxidant compounds but it can be contaminated by microorganisms. An experimental fluid bed ultraviolet (UV) reactor was designed for microbial decontamination of thyme samples and the effect of shortwave ultraviolet light (UV-C) radiation on antioxidant properties of thyme was studied. Samples were exposed to UV-C radiation for 16 or 64 min. UV-C treatment led to 1.04 and 1.38 log CFU/g reduction of total aerobic mesophilic bacteria (TAMB) counts. Hunter a(∗) value was the most sensitive colour parameter during UV-C treatment. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) scavenging activity of extracts was not significantly affected by UV-C. Addition of thyme extracts at 0.15 and 0.3 μmol GAE/ml emulsion delayed the formation of lipid hydroperoxides and headspace hexanal in the 5.0%(wt) corn oil-in-water emulsion from 4 to 9 and 14 days, respectively. No significant changes in oxidation rates were observed between UV-C treated and untreated samples at same concentrations. Copyright © 2014 Elsevier Ltd. All rights reserved.

UV-A radiation effects on higher plants: Exploring the known unknown.

PubMed

Verdaguer, Dolors; Jansen, Marcel A K; Llorens, Laura; Morales, Luis O; Neugart, Susanne

2017-02-01

Ultraviolet-A radiation (UV-A: 315-400nm) is a component of solar radiation that exerts a wide range of physiological responses in plants. Currently, field attenuation experiments are the most reliable source of information on the effects of UV-A. Common plant responses to UV-A include both inhibitory and stimulatory effects on biomass accumulation and morphology. UV-A effects on biomass accumulation can differ from those on root: shoot ratio, and distinct responses are described for different leaf tissues. Inhibitory and enhancing effects of UV-A on photosynthesis are also analysed, as well as activation of photoprotective responses, including UV-absorbing pigments. UV-A-induced leaf flavonoids are highly compound-specific and species-dependent. Many of the effects on growth and development exerted by UV-A are distinct to those triggered by UV-B and vary considerably in terms of the direction the response takes. Such differences may reflect diverse UV-perception mechanisms with multiple photoreceptors operating in the UV-A range and/or variations in the experimental approaches used. This review highlights a role that various photoreceptors (UVR8, phototropins, phytochromes and cryptochromes) may play in plant responses to UV-A when dose, wavelength and other conditions are taken into account. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

The effect of ultraviolet radiation on the cornea - experimental study.

PubMed

Golu, Andreea; Gheorghişor, Irina; Bălăşoiu, A T; Baltă, Fl; Osiac, E; Mogoantă, L; Bold, Adriana

2013-01-01

Ultraviolet (UV) radiation in high doses may have harmful effects on the eye. The sources of UV radiation are the sun, as well as some artificial sources such as UV lamps or voltaic arcs. Chronic exposure to UV can cause damage to the anterior pole of the eye, ranging from minor (pterygium) to serious photokeratitis. In our study, we applied a UV dose of 6.5 J/cm(2) in the wavelength range of 290-400 nm, for five consecutive days per rat anterior pole of the eye. Seven days after the last dose of radiation, the animals were sacrificed, harvesting both the irradiated and the non-irradiated eye. Histological and immunohistochemical examination of the lesions revealed that the greatest damage to the epithelium was recorded prior to and 2/3 of the remaining corneal stroma. The epithelial lesions we found varied from pseudokeratosis and detachment of the Bowman epithelium membrane to deep epithelial necrosis. Within the corneal stroma, we observed the formation of interstitial edema with disruption of the collagen structure. We also noticed the presence of an inflammatory infiltrate composed mainly of lymphocytes and CD68+ and CD163+ macrophages, as well as the occurrence of vascular devices. These consisted of angiogenesis capillaries with structured wall composed mainly of endothelial CD34+ precursor cells and a basal membrane rich in collagen IV fibers.

Response and Defense Mechanisms of Taxus chinensis Leaves Under UV-A Radiation are Revealed Using Comparative Proteomics and Metabolomics Analyses.

PubMed

Zheng, Wen; Komatsu, Setsuko; Zhu, Wei; Zhang, Lin; Li, Ximin; Cui, Lei; Tian, Jingkui

2016-09-01

Taxus chinensis var. mairei is a species endemic to south-eastern China and one of the natural sources for the anticancer medicine paclitaxel. To investigate the molecular response and defense mechanisms of T. chinensis leaves to enhanced ultraviolet-A (UV-A) radiation, gel-free/label-free and gel-based proteomics and gas chromatography-mass spectrometry (GC-MS) analyses were performed. The transmission electron microscopy results indicated damage to the chloroplast under UV-A radiation. Proteomics analyses in leaves and chloroplasts showed that photosynthesis-, glycolysis-, secondary metabolism-, stress-, and protein synthesis-, degradation- and activation-related systems were mainly changed under UV-A radiation. Forty-seven PSII proteins and six PSI proteins were identified as being changed in leaves and chloroplasts under UV-A treatment. This indicated that PSII was more sensitive to UV-A than PSI as the target of UV-A light. Enhanced glycolysis, with four glycolysis-related key enzymes increased, provided precursors for secondary metabolism. The 1-deoxy-d-xylulose-5-phosphate reductoisomerase and 4-hydroxy-3-methylbut-2-enyl diphosphate reductase were identified as being significantly increased during UV-A radiation, which resulted in paclitaxel enhancement. Additionally, mRNA expression levels of genes involved in the paclitaxel biosynthetic pathway indicated a down-regulation under UV-A irradiation and up-regulation in dark incubation. These results reveal that a short-term high dose of UV-A radiation could stimulate the plant stress defense system and paclitaxel production. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Diffraction spectral filter for use in extreme-UV lithography condenser

DOEpatents

Sweatt, William C.; Tichenor, Daniel A.; Bernardez, Luis J.

2002-01-01

A condenser system for generating a beam of radiation includes a source of radiation light that generates a continuous spectrum of radiation light; a condenser comprising one or more first optical elements for collecting radiation from the source of radiation light and for generating a beam of radiation; and a diffractive spectral filter for separating first radiation light having a particular wavelength from the continuous spectrum of radiation light. Cooling devices can be employed to remove heat generated. The condenser system can be used with a ringfield camera in projection lithography.

UV Reconstruction Algorithm And Diurnal Cycle Variability

NASA Astrophysics Data System (ADS)

Curylo, Aleksander; Litynska, Zenobia; Krzyscin, Janusz; Bogdanska, Barbara

2009-03-01

UV reconstruction is a method of estimation of surface UV with the use of available actinometrical and aerological measurements. UV reconstruction is necessary for the study of long-term UV change. A typical series of UV measurements is not longer than 15 years, which is too short for trend estimation. The essential problem in the reconstruction algorithm is the good parameterization of clouds. In our previous algorithm we used an empirical relation between Cloud Modification Factor (CMF) in global radiation and CMF in UV. The CMF is defined as the ratio between measured and modelled irradiances. Clear sky irradiance was calculated with a solar radiative transfer model. In the proposed algorithm, the time variability of global radiation during the diurnal cycle is used as an additional source of information. For elaborating an improved reconstruction algorithm relevant data from Legionowo [52.4 N, 21.0 E, 96 m a.s.l], Poland were collected with the following instruments: NILU-UV multi channel radiometer, Kipp&Zonen pyranometer, radiosonde profiles of ozone, humidity and temperature. The proposed algorithm has been used for reconstruction of UV at four Polish sites: Mikolajki, Kolobrzeg, Warszawa-Bielany and Zakopane since the early 1960s. Krzyscin's reconstruction of total ozone has been used in the calculations.

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

NASA Astrophysics Data System (ADS)

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

2016-12-01

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

UV scale calibration transfer from an improved pyroelectric detector standard to field UV-A meters and 365 nm excitation sources

NASA Astrophysics Data System (ADS)

Eppeldauer, G. P.; Podobedov, V. B.; Cooksey, C. C.

2017-05-01

Calibration of the emitted radiation from UV sources peaking at 365 nm, is necessary to perform the ASTM required 1 mW/cm2 minimum irradiance in certain military material (ships, airplanes etc) tests. These UV "black lights" are applied for crack-recognition using fluorescent liquid penetrant inspection. At present, these nondestructive tests are performed using Hg-lamps. Lack of a proper standard and the different spectral responsivities of the available UV meters cause significant measurement errors even if the same UV-365 source is measured. A pyroelectric radiometer standard with spectrally flat (constant) response in the UV-VIS range has been developed to solve the problem. The response curve of this standard determined from spectral reflectance measurement, is converted into spectral irradiance responsivity with <0.5% (k=2) uncertainty as a result of using an absolute tie point from a Si-trap detector traceable to the primary standard cryogenic radiometer. The flat pyroelectric radiometer standard can be used to perform uniform integrated irradiance measurements from all kinds of UV sources (with different peaks and distributions) without using any source standard. Using this broadband calibration method, yearly spectral calibrations for the reference UV (LED) sources and irradiance meters is not needed. Field UV sources and meters can be calibrated against the pyroelectric radiometer standard for broadband (integrated) irradiance and integrated responsivity. Using the broadband measurement procedure, the UV measurements give uniform results with significantly decreased uncertainties.

Modeling UV Radiation Feedback from Massive Stars. I. Implementation of Adaptive Ray-tracing Method and Tests

NASA Astrophysics Data System (ADS)

Kim, Jeong-Gyu; Kim, Woong-Tae; Ostriker, Eve C.; Skinner, M. Aaron

2017-12-01

We present an implementation of an adaptive ray-tracing (ART) module in the Athena hydrodynamics code that accurately and efficiently handles the radiative transfer involving multiple point sources on a three-dimensional Cartesian grid. We adopt a recently proposed parallel algorithm that uses nonblocking, asynchronous MPI communications to accelerate transport of rays across the computational domain. We validate our implementation through several standard test problems, including the propagation of radiation in vacuum and the expansions of various types of H II regions. Additionally, scaling tests show that the cost of a full ray trace per source remains comparable to that of the hydrodynamics update on up to ∼ {10}3 processors. To demonstrate application of our ART implementation, we perform a simulation of star cluster formation in a marginally bound, turbulent cloud, finding that its star formation efficiency is 12% when both radiation pressure forces and photoionization by UV radiation are treated. We directly compare the radiation forces computed from the ART scheme with those from the M1 closure relation. Although the ART and M1 schemes yield similar results on large scales, the latter is unable to resolve the radiation field accurately near individual point sources.

Photoemission Experiments for Charge Characteristics of Individual Dust Grains

NASA Technical Reports Server (NTRS)

Abbas, M. M.; Spann, James F., Jr.; Craven, Paul D.; West, E.; Pratico, Jared; Scheianu, D.; Tankosic, D.; Venturini, C. C.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

Photoemission experiments with UV radiation have been performed to investigate the microphysics and charge characteristics of individual isolated dust grains of various compositions and sizes by using the electrodynamic balance facility at NASA Marshall Space Flight Center. Dust particles of 1 - 100 micrometer diameter are levitated in a vacuum chamber at pressures approx. 10(exp -5) torr and exposed to a collimated beam of UV radiation in the 120-300 nanometers spectral range from a deuterium lamp source with a MgF2 window. A monochromator is used to select the UV radiation wavelength with a spectral resolution of 8 nanometers. The electrodynamic facility permits measurements of the charge and diameters of particles of known composition, and monitoring of photoemission rates with the incident UV radiation. Experiments have been conducted on Al2O3 and silicate particles, and in particular on JSC-1 Mars regolith simulants, to determine the photoelectron yields and surface equilibrium potentials of dust particles when exposed to UV radiation in the 120-250 micrometers spectral range. A brief discussion of the experimental procedure, the results of photoemission experiments, and comparisons with theoretical models will be presented.

[Ultraviolet radiation-induced apoptosis in human lens epithelial cells and its effect on Bcl-2 and Bax].

PubMed

Jia, Songbai; Shi, Jingming; Chen, Xuan; Tang, Luosheng

2012-07-01

To explore the apoptosis-inducing effect of ultraviolet(UV) radiation on human lens epithelial cells (HLEC), with particular focus on changes in Bcl-2 or Bax expression as possible mechanisms. All experimental groups were exposed to the same UV light source. HLEC were divided into 6 groups according to duration of UV radiation : 0 min group (control group), 5 min group, 10 min group,15 min group, and 30 min group. Analysis on apoptosis of HLEC was performed by flow cytometry analysis (FCA, Annexin V + PI staining). Changes of Bax and Bcl-2 expression in HLEC were detected by hybridization in situ. Apoptosis in HLEC increased with UV exposure time. The expression level of Bax mRNA was increased with the increase of UV exposure time, whereas the expression level of Bcl-2 mRNA decreased with the increase of UV exposure time. The proportion of apoptotic cells was negatively correlated with ratio of Bcl-2/Bax (r=-0.874, P<0.05). UA radiation can induce apoptosis of HLEC in vitro. Bcl-2 and Bax genes may play an important role in regulating this apoptotic process.

Photoemission Experiments for Charge Characteristics of Individual Dust Grains

NASA Technical Reports Server (NTRS)

Abbas, M. M.; Craven, P. D.; Spann, J. F.; West, E.; Pratico, J.; Tankosic, D.; Venturini, C. C.; Six, N. Frank (Technical Monitor)

2001-01-01

Photoemission experiments with UV radiation have been performed to investigate the microphysics and charge characteristics of individual isolated dust grains of various compositions and sizes by using the electrodynamic balance facility at NASA Marshall Space Flight Center. Dust particles of 2-10 gm diameter are levitated in a vacuum chamber at pressures approximately 10(exp-5) torr and exposed to a collimated beam of UV radiation in the 120-200 nm spectral range from a deuterium lamp source with a MgF2 window. A monochromator is used to select the UV wavelength with a spectral resolution of 8 nm. The electrodynamic facility permits measurements of the charge and diameters of particles of known composition, and monitoring of photoemission rates with the incident UV radiation. Experiments have been conducted on test particles of silica and polystyrene to determine the photoelectric yields and surface equilibrium potentials when exposed to UV radiation. A brief description of an experimental procedure for photoemission studies is given and some preliminary laboratory measurements of the photoelectric yields of individual dust particles are presented.

Geometrically Thick Obscuration by Radiation-driven Outflow from Magnetized Tori of Active Galactic Nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chan, Chi-Ho; Krolik, Julian H.

2017-07-01

Near-Eddington radiation from active galactic nuclei (AGNs) has significant dynamical influence on the surrounding dusty gas, plausibly furnishing AGNs with geometrically thick obscuration. We investigate this paradigm with radiative magnetohydrodynamics simulations. The simulations solve the magnetohydrodynamics equations simultaneously with the infrared (IR) and ultraviolet (UV) radiative transfer (RT) equations; no approximate closure is used for RT. We find that our torus, when given a suitable sub-Keplerian angular momentum profile, spontaneously evolves toward a state in which its opening angle, density distribution, and flow pattern change only slowly. This “steady” state lasts for as long as there is gas resupply towardmore » the inner edge. The torus is best described as a midplane inflow and a high-latitude outflow. The outflow is launched from the torus inner edge by UV radiation and expands in solid angle as it ascends; IR radiation continues to drive the wide-angle outflow outside the central hole. The dusty outflow obscures the central source in soft X-rays, the IR, and the UV over three-quarters of solid angle, and each decade in column density covers roughly equal solid angle around the central source; these obscuration properties are similar to what observations imply.« less

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

NASA Astrophysics Data System (ADS)

Popov, Dmitri; Jones, Jeffrey; Maliev, Slava

Key Words: Ultraviolet radiation,Standard Erythema Dose(SED), Minimal Erythema Dose(MED), Sun Burns, Solar Dermatitis, Sun Burned Disease, DNA Damage,Cell Damage, Antiradiation UV Vaccine, Immune-Prophylaxis of Sun Burned Diseases, Immune-Prophylaxis of Sun Burns, Immune-Therapy of Sun-Burned Disease and Sun Burns,Basal Cell Carcinoma (BCC), Squamous Cell Carcinoma (SCC), Toxic Epidermal Necrolysis(TEN). Introduction: High doses of UV generated by solar source and artificial sources create an exposure of mammals and other species which can lead to ultraviolet(UV)radiation- associated disease (including erythema, epilation, keratitis, etc.). UV radiation belongs to the non-ionizing part of the electromagnetic spectrum and ranges between 100 nm and 400 nm with 100 nm having been chosen arbitrarily as the boundary between non-ionizing and ionizing radiation, however EMR is a spectrum and UV can produce molecular ionization. UV radiation is conventionally categorized into 3 areas: UV-A (>315-400 nm),UV-B (>280-315 nm)and UV-C (>100-280 nm) [IARC,Working Group Reports,2005] An important consequence of stratospheric ozone depletion is the increased transmission of solar ultraviolet (UV)radiation to the Earth's lower atmosphere and surface. Stratospheric ozone levels have been falling, in certain areas, for the past several decades, so current surface ultraviolet-B (UV-B) radiation levels are thought to be close to their modern day maximum. [S.Madronich et al.1998] Overexposure of ultraviolet radiation a major cause of skin cancer including basal cell carcinoma (BCC), squamous cell carcinoma (SCC) { collectively referred to as “non-melanoma" skin cancer (NMSC) and melanoma as well, with skin cancers being the most common cancer in North America. [Armstrong et al. 1993, Gallagher et al. 2005] Methods and Experimental Design: Our experiments and testing of a novel UV “Antiradiation Vaccine” have employed a wide variety of laboratory animals which include : Chinchilla rabbits, 11-12 months old, live weight 3.5-3.7 (n=11), Balb mice, 2-3 months old, live weight 20-22 g (n=33), Wistar rats, 3-4 months old, live weight 180-220 g(n=33). The studies were approved by the Animal Care and Use Committee for ethical animal research equivalent, at each institution. Seven rabbits, ten mice, eleven Wistar rats were vaccinated with a UV antiradiation vaccine. A second group of animals was used as biological control which received vaccine but no UV Radiation and a third group of animals was used as control without any interventions. Before and after UV Radiation, Vaccination with the UV antiradiation vaccine were provided 17 days prior to UV exposure. The animals were irradiated by a DRT-1 UV generator lamp. The dose of irradiation for laboratory, experimental animals was 10-12 * Standard Erythema Dose (SED) at L=283,7 Laboratory animals were placed in to the box with ventilation. Results: Ultraviolet irradiation of the skin was performed with high doses and causes an inflammation or erythema in all experimental animals. However the grade of skin damage and inflammation was significantly different between animals protected by vaccination and non-protected, non-vaccinated animals. Animals UV-irradiated, but who did not receive the antiradiation vaccine suffered from extensive UV skin burns of second or third degree (grade 2-3). However, animals protected with the UV antiradiation vaccine demonstrated much mild forms of skin cellular injury - mainly erythema, first degree skin burns and a few small patches with second degree skin burns (grade 1-2). Discussion: The severity of skin damage depended on area of exposed skin, time and dose of UV irradiation. Skin injury could be divided into 4 major grades: 1. Faint erythema with dry desquamation. 2. Moderate to severe erythema. 3. Severe erythema with blistering, moist desquamation. 4. Toxic epidermal necrolysis. Mild doses of UV radiation and ionizing radiation can induce cell death by apoptosis and moderate and high doses of UV and ionizing radiation induce cell death by necrosis and generate systemic inflammatory response syndrome (SIRS), toxic multiple organ injury (TMOI), toxic multiple organ dysfunction syndromes (TMODS),and finally, toxic multiple organ failure (TMOF). [D.Popov et al.2012, Fliedner T.et al. 2005, T. Azizova et al. 2004] UV-B is a complete carcinogen that is absorbed by DNA and directly damages DNA. DNA damage induced by UV-B irradiation typically includes the formation of cyclobutane pyrimidine dimmers (CPD) and 6-4 photoproducts (6-4P)[IARC, Working Group Reports, M.Saraiya et al. 2004]. The pre-vaccinated animals seem to have a blunted injury response relative to the unvaccinated animals, presumably by reduction in the inflammatory response and secondary injury effects. The mechanism of action of the antiradiation vaccine, needs further evaluation. Conclusion: A UV antiradiation vaccine appears to demonstrate efficacy as a prophylactic agent for acute solar burns and toxicity. An antiradiation UV vaccine could be used in conjunction with adjunctive measures, e.g. antioxidants and UV barriers to reduce UV radiation toxicity. The authors of this experiments would like to propose further development work of the antiradiation UV vaccine to enhance the armamentarium for prophylaxis and prevention of the various forms skin cancer.

Differential toxicity of drinking water disinfected with combinations of ultraviolet radiation and chlorine.

PubMed

Plewa, Michael J; Wagner, Elizabeth D; Metz, Deborah H; Kashinkunti, Ramesh; Jamriska, Katherine J; Meyer, Maria

2012-07-17

Alternative technologies to disinfect drinking water such as ultraviolet (UV) disinfection are becoming more widespread. The benefits of UV disinfection include reduced risk of microbial pathogens such as Cryptosporidium and reduced production of regulated drinking water disinfection byproducts (DBPs). The objective of this research was to determine if mammalian cell cytotoxicity and genotoxicity varied in response to different chlorination protocols with and without polychromatic medium pressure UV (MPUV) and monochromatic low pressure UV (LPUV) disinfection technologies. The specific aims were to analyze the mammalian cell cytotoxicity and genotoxicity of concentrated organic fractions from source water before and after chlorination and to determine the cytotoxicity and genotoxicity of the concentrated organic fractions from water samples treated with UV alone or UV before or after chlorination. Exposure of granular activated carbon-filtered Ohio River water to UV alone resulted in the lowest levels of mammalian cell cytotoxicity and genotoxicity. With combinations of UV and chlorine, the lowest levels of cytotoxicity and genotoxicity were observed with MPUV radiation. The best combined UV plus chlorine methodology that generated the lowest cytotoxicity and genotoxicity employed chlorination first followed by MPUV radiation. These data may prove important in the development of multibarrier methods of pathogen inactivation of drinking water, while limiting unintended toxic consequences.

Wavelength dependent recovery of UV-mediated damage: Tying up the loose ends of optical based powdery mildew management.

PubMed

Suthaparan, Aruppillai; Pathak, Ranjana; Solhaug, Knut Asbjørn; Gislerød, Hans Ragnar

2018-01-01

Controlled environment chamber experiments at Petri dish level were conducted to examine the wavelength and dose dependent efficacy of ultraviolet (UV) radiation, the recovery action potential of optical radiation applied concomitantly/subsequently to effective UV treatment, and the lapse time between UV treatment and subsequent exposure to recovery wavelength on germination efficiency of Oidium neolycopersici conidia. Conidia of eight- to nine-day-old colonies were dusted on water agar surface in Petri dishes and exposed to UV treatments (without lid). Immediately after UV treatments, Petri dishes were sealed and incubated in darkness or differing optical environments generated using seven different radiation sources (range 290nm to 780nm). Twenty-four hours after UV treatment, fifty conidia from each sample were assessed for germination. Compared to non-UV controls, <10% of the conidia germinated after 30s of exposure to 254nm or 283nm UV and subsequent dark incubation. Conidia germination was almost negligible if the exposure duration increased to 4min. Germination was about 60% with broad spectrum UV after 1min of exposure, and about 35% after 2 to 4min of exposure. There was no reduction of conidia germination with the exposure of ≤4min with 310nm. With the tested wavelength and dose ranges, germination recovery was effective in the 350nm to 500nm range. Germination efficiency of conidia treated with effective UV was significantly higher (>73%) if incubated subsequently in the 350nm to 500nm range (germination recovery). Furthermore, germination recovery depends on the characteristics of UV treatment (wavelength, and duration of exposure) and the lapse time between UV treatment and subsequent exposure to optical radiation in the recovery range. The findings of this study provide key criteria for wavelength selection, combination and application time in the optical radiation range, enabling improved design of optical based management strategies against powdery mildews. Copyright © 2017 Elsevier B.V. All rights reserved.

New apparatus with high radiation energy between 320-460 nm: physical description and dermatological applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mutzhas, M.F.; Holzle, E.; Hofmann, C.

1981-01-01

A new apparatus (UVASUN 5000) is presented with high-radiation energy between 320 to 460 nm. The measureable energy below 320 nm was shown to be many orders of magnitude too low to produce erythema. The radiator is a specially developed source for high uv-A intensity, housing a quartz bulb with a mixture of argon, mercury and metal-halides. At a skin-target distance of 0.2 m the size of the irradiated area is 0.35 x 0.35 m, and the measured mean uv-A intensity is about 1400 W. m-2 (140 mW . cm-2). The uv-A energy in the range of 320 to 400more » nm is about 84% of the total radiation energy. Effects of very high doses of uv-A on human skin were studied. Following single uv-a applications the minimal tanning dose uv-A (MTD) and the immediate pigment darkening (IPD) dose of uv-A were established. The calculated IPD threshold time was 1.8 min at 0.2 m. Repeated exposure to this uv-A delivering system yields long lasting dark brown skin pigmentation without any clinical or histological signs of sunburn (uv-B) damage, epidermal hyperplasia or thickening of the stratum corneum. The instrument was also successfully used for photo-patch testing and reproduction of skin lesions of polymorphous light eruption. Minimal therapeutic results were seen in the phototherapy of vitiligo and inflammatory acne.« less

Luminescent Characteristics of a Pulsed Discharge Plasma in Xe-KBr Mixture

NASA Astrophysics Data System (ADS)

Heneral, A. A.; Zhmenyak, Y. V.

2018-03-01

A mixture of xenon with a nontoxic halogen carrier Xe-KBr is used to create a plasma radiation source at the 282-nm transition of the XeBr* molecule excited by a high-voltage pulsed-periodic discharge. The luminescence spectra of the plasma of a longitudinal pulsed-periodic discharge in the Xe-KBr mixture at low pressures are studied experimentally. The most intense UV bands of exciplex XeBr* molecules are recorded in the spectral range of 250-350 nm. The spectral, temporal, and energetic characteristics of the radiation source are presented, as well as the dependence of the XeBr* exciplex molecule formation efficiency on the discharge excitation conditions. The optimal conditions for the excitation of UV radiation in the pulsed-periodic discharge plasma are determined.

Constraining the Accretion Mode in LINER 1.9s

NASA Astrophysics Data System (ADS)

Sabra, Bassem; Der Sahaguian, Elias; Badr, Elie

2016-01-01

The accretion mode and the dominant power source in low-ionization nuclear emission-line regions (LINERs), a class of active galactic nuclei (AGN), are still elusive. We focus on a sample of 22 LINER 1.9s (Ho et al. 1997), a subclass of LINERs that show broad Halpha lines, a signature of blackhole-powered accretion, to test the hypothesis that the ionizing continuum emitted by a radiatively inefficient accretion flow (RIAF) could lead to the LINER ultraviolet (UV) emission-line ratios. Optical line-ratio diagrams are a weak diagnostic tool in distinguishing between possible power sources (Sabra et al. 2003). We search the Mikulski Archive for Space Telescopes (MAST) for UV spectra of the objects in the above sample and also perform photoionization simulations using CLOUDY (Ferland et al. 2013). Unfortunately, only one object (NGC 1052; Gabel et al. 2000) of the 22 LINER 1.9s has UV spectra that cover many emission lines; the rest of the objects either do not have any UV spectra, the spectral coverage is in-adequate, or the spectra have very low signal-to-noise ratios. Our photoionization simulations set up two identical grids of clouds with a range of densities and ionization parameters. We illuminate one grid with radiation emitted by a thin accretion disk (AD) and we illuminate the other grid with radiation from a RIAF. We overplot the UV emission-line ratio predictions for AD and RIAF illumination, together with the available line ratios for NGC 1052. Initial results show that UV lines could be used as diagnostics for the accretion mode in AGN. More UV spectral coverage of LINER 1.9s is needed in order to more fully utilize the diagnostic powers of UV emission line ratios.

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

PubMed

Kheyrandish, Ataollah; Mohseni, Madjid; Taghipour, Fariborz

2017-10-01

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

UV-Visible Absorption Spectroscopy Enhanced X-ray Crystallography at Synchrotron and X-ray Free Electron Laser Sources.

PubMed

Cohen, Aina E; Doukov, Tzanko; Soltis, Michael S

2016-01-01

This review describes the use of single crystal UV-Visible Absorption micro-Spectrophotometry (UV-Vis AS) to enhance the design and execution of X-ray crystallography experiments for structural investigations of reaction intermediates of redox active and photosensitive proteins. Considerations for UV-Vis AS measurements at the synchrotron and associated instrumentation are described. UV-Vis AS is useful to verify the intermediate state of an enzyme and to monitor the progression of reactions within crystals. Radiation induced redox changes within protein crystals may be monitored to devise effective diffraction data collection strategies. An overview of the specific effects of radiation damage on macromolecular crystals is presented along with data collection strategies that minimize these effects by combining data from multiple crystals used at the synchrotron and with the X-ray free electron laser.

Standardization of UV LED measurements

NASA Astrophysics Data System (ADS)

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

2015-09-01

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

History of UV Lamps, Types, and Their Applications.

PubMed

Ahmad, Shamim I; Christensen, Luisa; Baron, Elma

2017-01-01

The use of ultraviolet (UV) light, for the treatment of skin conditions, dates back to the early 1900s. It is well known that sunlight can be of therapeutic value, but it can also lead to deleterious effects such as burning and carcinogenesis. Extensive research has expanded our understanding of UV radiation and its effects in human systems and has led to the development of man-made UV sources that are more precise, safer, and more effective for the treatment of wide variety of dermatologic conditions.

Coupled microwave/photoassisted methods for environmental remediation.

PubMed

Horikoshi, Satoshi; Serpone, Nick

2014-11-05

The microwave-induced acceleration of photocatalytic reactions was discovered serendipitously in the late 1990s. The activity of photocatalysts is enhanced significantly by both microwave radiation and UV light. Particularly relevant, other than as a heat source, was the enigmatic phenomenon of the non-thermal effect(s) of the microwave radiation that facilitated photocatalyzed reactions, as evidenced when examining various model contaminants in aqueous media. Results led to an examination of the possible mechanism(s) of the microwave effect(s). In the present article we contend that the microwaves' non-thermal effect(s) is an important factor in the enhancement of TiO2-photoassisted reactions involving the decomposition of organic pollutants in model wastewaters by an integrated (coupled) microwave-/UV-illumination method (UV/MW). Moreover, such coupling of no less than two irradiation methods led to the fabrication and ultimate investigation of microwave discharged electrodeless lamps (MDELs) as optimal light sources; their use is also described. The review focuses on the enhanced activity of photocatalytic reactions when subjected to microwave radiation and concentrates on the authors' research of the past few years.

[Effect of long-wave ultraviolet light (UV-A) and medium-wave ultraviolet rays (UV-B) on human skin. Critical comparison].

PubMed

Raab, W

1980-04-15

When discussing the effects of ultraviolet radiation on human skin, one should carefully distinguish between the long wave ultraviolet light (UV-A) and the short wave radiations (UV-B and UV-C). Ultraviolet A induces immediate pigmentation but, if high energies are applied, a permanent pigmentation is elicited. This type of ultraviolet A-induced pigmentation has been called "spontaneous" pigmentation as no erythematous reaction is necessary to induce or accelerate melanine formation. Ultraviolet B provokes erythema and consecutive pigmentation. Upon chronic exposure, ultraviolet B causes the wellknown actinic damage of the skin and even provokes carcinoma. With exposures to the sunlight (global radiation), one should be most careful. The public must be informed extensively about the dangers of excessive sunbaths. The use of artificial "suns" with spectra between 260 and 400 nm is limited as it may cause the same type of damage as the global radiation. An exact schedule for use of artificial lamps is strongly recommended. After one cycle of exposures, an interruption is necessary until the next cycle of irradiations may start. Upon continual use for tanning of the skin, artificial lamps may provoke irreversible damage of the skin. Radiation sources with emission spectra of wavelengths between 315 and 400 nm exclusively are well suited for the induction of skin pigmentation (cosmetic use). Potent radiation such as UVASUN systems provoke a "pleasant" permanent pigmentation after exposures for less than one hour. The use of ultraviolet A (UV-A) does not carry any risk for the human skin.

Theoretical and experimental luminous characteristics of white LEDs composed of multiphosphors and near-UV LED for lighting

NASA Astrophysics Data System (ADS)

Uchida, Yuji; Taguchi, Tsunemasa

2003-07-01

We have performed theoretical studies on the luminous characeristics of white LED light source which composed of multi phosphors and near ultraviolet (UV) LED for general lighting. White LED source for general lighting applications requires the conditions that have high-flux, high luminous efficacy of radiation (> 100 lm/W) in addition to high color rendering index (Ra > 90) and variable color temperatures. Recently, we have proposed a novel type white LED based on multi phosphors and near UV LED system in order to high-Ra (>93). We will describe the excellent luminescence properties of white LED consisting of orange (O), yellow (Y), green (G) and blue (B) phosphor materials, and near UV LED. The color spectral contributions of individual phosphor-coated LED are theoretically analyzed using our multi LED lighting theory calculated the maximum luminous efficacy can be estimated to be approximately 300 lm/W having a high Ra of about 90 taking into account individual radiation spectrum. Illuminance distribution of white LED is in fairly good agreement with the experimental data.

Interactive effects of UV radiation and reduced precipitation on the seasonal leaf phenolic content/composition and the antioxidant activity of naturally growing Arbutus unedo plants.

PubMed

Nenadis, Nikolaos; Llorens, Laura; Koufogianni, Agathi; Díaz, Laura; Font, Joan; Gonzalez, Josep Abel; Verdaguer, Dolors

2015-12-01

The effects of UV radiation and rainfall reduction on the seasonal leaf phenolic content/composition and antioxidant activity of the Mediterranean shrub Arbutus unedo were studied. Naturally growing plants of A. unedo were submitted to 97% UV-B reduction (UVA), 95% UV-A+UV-B reduction (UV0) or near-ambient UV levels (UVBA) under two precipitation regimes (natural rainfall or 10-30% rainfall reduction). Total phenol, flavonol and flavanol contents, levels of eight phenols and antioxidant activity [DPPH(●) radical scavenging and Cu (II) reducing capacity] were measured in sun-exposed leaves at the end of four consecutive seasons. Results showed a significant seasonal variation in the leaf content of phenols of A. unedo, with the lowest values found in spring and the highest in autumn and/or winter. Leaf ontogenetic development and/or a possible effect of low temperatures in autumn/winter may account for such findings. Regardless of the watering regime and the sampling date, plant exposure to UV-B radiation decreased the total flavanol content of leaves, while it increased the leaf content in quercitrin (the most abundant quercetin derivative identified). By contrast, UV-A radiation increased the leaf content of theogallin, a gallic acid derivative. Other phenolic compounds (two quercetin derivatives, one of them being avicularin, and one kaempferol derivative, juglanin), as well as the antioxidant activity of the leaves, showed different responses to UV radiation depending on the precipitation regime. Surprisingly, reduced rainfall significantly decreased the total amount of quantified quercetin derivatives as well as the DPPH scavenging activity in A. unedo leaves. To conclude, present findings indicate that leaves of A. unedo can be a good source of antioxidants throughout the year, but especially in autumn and winter. Copyright © 2015 Elsevier B.V. All rights reserved.

Study of UV cloud modification factors in Southern Patagonia

NASA Astrophysics Data System (ADS)

Wolfram, Elian A.; Orte, Facundo; Salvador, Jacobo; Quiroga, Jonathan; D'Elia, Raúl; Antón, Manuel; Alados-Arboledas, Lucas; Quel, Eduardo

2017-02-01

Anthropogenic perturbation of the ozone layer has induced change in the amount of UV radiation that reaches the Earth's surface, mainly through the Antarctic ozone hole, making the ozone and ultraviolet (UV) radiation two important issues in the study of Earth atmosphere in the scientific community. Also the clouds have been identified as the main modulator of UV amount in short time scales and produce the main source of uncertainty in the projection of surface UV level as consequence of projected ozone recovery. While clouds can decrease direct radiation, they can produce an increase in the diffuse component, and as consequence the surface UV radiation may be higher than an equivalent clear sky scenario for several minutes. In particular this situation can be important when low ozone column and partially cloud cover skies happen simultaneously. These situations happen frequently in southern Patagonia, where the CEILAP Lidar Division has established the Atmospheric Observatory of Southern Patagonia, an atmospheric remote sensing site near the city of Río Gallegos (51°55'S, 69°14'W). In this paper, the impact of clouds over the UV radiation is investigated by the use of ground based measurements from the passive remote sensing instruments operating at this site, mainly of broad and moderate narrow band filter radiometers. We analyzed the UV Index obtained from a multiband filter radiometer GUV-541 (UVI) [Biospherical Inc.] installed in the Observatorio Atmosférico de la Patagonia Austral, Río Gallegos, since 2005. Cloud modification factors (CMF, ratio between the measured UV radiation in a cloudy sky and the simulated radiation under cloud-free conditions) are evaluated for the study site. The database used in this work covers the period 2005-2012 for spring and summer seasons, when the ozone hole can affect these subpolar regions. CMF higher than 1 are found during spring and summer time, when lower total ozone columns, higher solar elevations and high cloud cover occur simultaneously, producing extreme erythemal irradiance at ground surface. Enhancements as high as 25% were registered. The maximum duration of the enhancement was around 30 minute. This produces dangerous sunbathing situations for the Río Gallegos citizen.

A high-performance doped photocatalysts for inactivation of total coliforms in superficial waters using different sources of radiation.

PubMed

Claro, Elis Marina Turini; Bidoia, Ederio Dino; de Moraes, Peterson Bueno

2016-07-15

Photocatalytic water treatment has a currently elevated electricity demand and maintenance costs, but the photocatalytic water treatment may also assist in overcoming the limitations and drawbacks of conventional water treatment processes. Among the Advanced Oxidation Processes, heterogeneous photocatalysis is one of the most widely and efficiently used processes to degrade and/or remove a wide range of polluting compounds. The goal of this work was to find out a highly efficient photocatalytic disinfection process in superficial water with different doped photocatalysts and using three sources of radiation: mercury vapor lamp, solar simulator and UV-A LED. Three doped photocatalysts were prepared, SiZnO, NSiZnO and FNSiZnO. The inactivation efficiency of each synthesized photocatalysts was compared to a TiO2 P25 (Degussa(®)) 0.5 g L(-1) control. Photolysis inactivation efficiency was 85% with UV-A LED, which is considered very high, demanding low electricity consumption in the process, whereas mercury vapor lamp and solar simulator yielded 19% and 13% inactivation efficiency, respectively. The best conditions were found with photocatalysts SiZnO, FNSiZnO and NSiZnO irradiated with UV-A LED, where efficiency exceeded 95% that matched inactivation of coliforms using the same irradiation and photocatalyst TiO2. All photocatalysts showed photocatalytic activity with all three radiation sources able to inactivate total coliforms from river water. The use of UV-A LED as the light source without photocatalyst is very promising, allowing the creation of cost-effective and highly efficient water treatment plants. Copyright © 2016 Elsevier Ltd. All rights reserved.

X-Rays from the Location of the Double-humped Transient ASASSN-15lh

NASA Astrophysics Data System (ADS)

Margutti, R.; Metzger, B. D.; Chornock, R.; Milisavljevic, D.; Berger, E.; Blanchard, P. K.; Guidorzi, C.; Migliori, G.; Kamble, A.; Lunnan, R.; Nicholl, M.; Coppejans, D. L.; Dall'Osso, S.; Drout, M. R.; Perna, R.; Sbarufatti, B.

2017-02-01

We present the detection of persistent soft X-ray radiation with {L}x˜ {10}41-1042 erg s-1 at the location of the extremely luminous, double-humped transient ASASSN-15lh as revealed by Chandra and Swift. We interpret this finding in the context of observations from our multiwavelength campaign, which revealed the presence of weak narrow nebular emission features from the host-galaxy nucleus and clear differences with respect to superluminous supernova optical spectra. Significant UV flux variability on short timescales detected at the time of the rebrightening disfavors the shock interaction scenario as the source of energy powering the long-lived UV emission, while deep radio limits exclude the presence of relativistic jets propagating into a low-density environment. We propose a model where the extreme luminosity and double-peaked temporal structure of ASASSN-15lh is powered by a central source of ionizing radiation that produces a sudden change in the ejecta opacity at later times. As a result, UV radiation can more easily escape, producing the second bump in the light curve. We discuss different interpretations for the intrinsic nature of the ionizing source. We conclude that, if the X-ray source is physically associated with the optical-UV transient, then ASASSN-15lh most likely represents the tidal disruption of a main-sequence star by the most massive spinning black hole detected to date. In this case, ASASSN-15lh and similar events discovered in the future would constitute the most direct probes of very massive, dormant, spinning, supermassive black holes in galaxies. Future monitoring of the X-rays may allow us to distinguish between the supernova hypothesis and the hypothesis of a tidal disruption event.

X-Rays from the Location of the Double-humped Transient ASASSN-15lh

PubMed Central

Margutti, R.; Metzger, B. D.; Chornock, R.; Milisavljevic, D.; Berger, E.; Blanchard, P. K.; Guidorzi, C.; Migliori, G.; Kamble, A.; Lunnan, R.; Nicholl, M.; Coppejans, D. L.; Dall’Osso, S.; Drout, M. R.; Perna, R.; Sbarufatti, B.

2017-01-01

We present the detection of persistent soft X-ray radiation with Lx ~ 1041–1042 erg s−1 at the location of the extremely luminous, double-humped transient ASASSN-15lh as revealed by Chandra and Swift. We interpret this finding in the context of observations from our multiwavelength campaign, which revealed the presence of weak narrow nebular emission features from the host-galaxy nucleus and clear differences with respect to superluminous supernova optical spectra. Significant UV flux variability on short timescales detected at the time of the rebrightening disfavors the shock interaction scenario as the source of energy powering the long-lived UV emission, while deep radio limits exclude the presence of relativistic jets propagating into a low-density environment. We propose a model where the extreme luminosity and double-peaked temporal structure of ASASSN-15lh is powered by a central source of ionizing radiation that produces a sudden change in the ejecta opacity at later times. As a result, UV radiation can more easily escape, producing the second bump in the light curve. We discuss different interpretations for the intrinsic nature of the ionizing source. We conclude that, if the X-ray source is physically associated with the optical–UV transient, then ASASSN-15lh most likely represents the tidal disruption of a main-sequence star by the most massive spinning black hole detected to date. In this case, ASASSN-15lh and similar events discovered in the future would constitute the most direct probes of very massive, dormant, spinning, supermassive black holes in galaxies. Future monitoring of the X-rays may allow us to distinguish between the supernova hypothesis and the hypothesis of a tidal disruption event. PMID:28966348

Ultraviolet germicidal efficacy as a function of pulsed radiation parameters studied by spore film dosimetry.

PubMed

Bauer, Stefan; Holtschmidt, Hans; Ott, Günter

2018-01-01

Disinfection by pulsed ultraviolet (UV) radiation is a commonly used method, e.g. in industry or medicine and can be carried out either with lasers or broadband UV radiation sources. Detrimental effects to biological materials depending on parameters such as pulse duration τ or pulse repetition frequency f p are well-understood for pulsed coherent UV radiation, however, relatively little is known for its incoherent variant. Therefore, within this work, it is the first time that disinfection rates of pulsed and continuous (cw) incoherent UV radiation studied by means of spore film dosimetry are presented, compared with each other, and in a second step further investigated regarding two pulse parameters. After analyzing the dynamic range of the Bacillus subtilis spore films with variable cw radiant exposures H=5-100Jm -2 a validation of the Bunsen-Roscoe law revealed its restricted applicability and a 28% enhanced detrimental effect of pulsed compared to cw incoherent UV radiation. A radiant exposure H=50Jm -2 and an irradiance E=0.5Wm -2 were found to be suitable parameters for an analysis of the disinfection rate as a function of τ=0.5-10ms and f p =25-500Hz unveiling that shorter pulses and lower frequencies inactivate more spores. Finally, the number of applied pulses as well as the experiment time were considered with regard to spore film disinfection. Copyright © 2017 Elsevier B.V. All rights reserved.

Cavitation induced Becquerel effect.

PubMed

Prevenslik, T V

2003-06-01

The observation of an electrical current upon the ultraviolet (UV) illumination of one of a pair of identical electrodes in liquid water, called the Becquerel effect, was made over 150 years ago. More recently, an electrical current was found if the water surrounding one electrode was made to cavitate by focused acoustic radiation, the phenomenon called the cavitation induced Becquerel effect. Since cavitation is known to produce UV light, the electrode may simply absorb the UV light and produce the current by the photo-emission theory of photoelectrochemistry. But the current was found to be semi-logarithmic with the standard electrode potential which is characteristic of the oxidation of the electrode surface in the photo-decomposition theory, and not the photo-emission theory. High bubble collapse temperatures may oxidize the electrode, but this is unlikely because melting was not observed on the electrode surfaces. At ambient temperature, oxidation may proceed by chemical reaction provided a source of vacuum ultraviolet (VUV) radiation is available to produce the excited OH* states of water to react with the electrode. The source of VUV radiation is shown to be the spontaneous emission of coherent infrared (IR) radiation from water molecules in particles that form in bubbles because of surface tension, the spontaneous IR emission induced by cavity quantum electrodynamics. The excited OH* states are produced as the IR radiation accumulates to VUV levels in the bubble wall molecules.

Repetitively pulsed UV radiation source based on a run-away electron preionised diffuse discharge in nitrogen

NASA Astrophysics Data System (ADS)

Baksht, E. Kh; Burachenko, A. G.; Lomaev, M. I.; Panchenko, A. N.; Tarasenko, V. F.

2015-04-01

An extended repetitively pulsed source of spontaneous UV radiation is fabricated, which may also be used for producing laser radiation. Voltage pulses with an incident wave amplitude of up to 30 kV, a half-amplitude duration of ~4 ns and a rise time of ~2.5 ns are applied to a gap with a nonuniform electric field. For an excitation region length of 35 cm and a nitrogen pressure of 30 - 760 Torr, a diffusive discharge up to a pulse repetition rate of 2 kHz is produced without using an additional system for gap preionisation. An investigation is made of the plasma of the run-away electron preionised diffuse discharge. Using a CCD camera it is found that the dense diffused plasma fills the gap in a time shorter than 1 ns. X-ray radiation is recorded from behind the foil anode throughout the pressure range under study; a supershort avalanche electron beam is recorded by the collector electrode at pressures below 100 Torr.

SCHOTT optical glass in space

NASA Astrophysics Data System (ADS)

Jedamzik, Ralf; Petzold, Uwe

2017-09-01

Optical systems in space environment have to withstand harsh radiation. Radiation in space usually comes from three main sources: the Van Allen radiation belts (mainly electrons and protons); solar proton events and solar energetic particles (heavier ions); and galactic cosmic rays (gamma- or x-rays). Other heavy environmental effects include short wavelength radiation (UV) and extreme temperatures (cold and hot). Radiation can damage optical glasses and effect their optical properties. The most common effect is solarization, the decrease in transmittance by radiation. This effect can be observed for UV radiation and for gamma or electron radiation. Optical glasses can be stabilized against many radiation effects. SCHOTT offers radiation resistant glasses that do not show solarization effects for gamma or electron radiation. A review of SCHOTT optical glasses in space missions shows, that not only radiation resistant glasses are used in the optical designs, but also standard optical glasses. This publication finishes with a selection of space missions using SCHOTT optical glass over the last decades.

An auroral oval at the footprint of Saturn's kilometric radio sources, colocated with the UV aurorae

NASA Astrophysics Data System (ADS)

Lamy, L.; Cecconi, B.; Prangé, R.; Zarka, P.; Nichols, J. D.; Clarke, J. T.

2009-10-01

Similarly to other magnetized planets, Saturn displays auroral emissions generated by accelerated electrons gyrating around high-latitude magnetic field lines. They mainly divide in ultraviolet (UV) and infrared (IR) aurorae, excited by electron collisions with the upper atmosphere, and Saturn's kilometric radiation (SKR), radiated from higher altitudes by electron-wave resonance. Whereas spatially resolved UV and IR images of atmospheric aurorae reveal a continuous auroral oval around each pole, the SKR source locus was only indirectly constrained by the Voyager radio experiment to a limited local time (LT) range on the morningside, leading to interpretation of the SKR modulation as a fixed flashing light. Here, we present resolved SKR maps derived from the Cassini Radio and Plasma Wave Science (RPWS) experiment using goniopolarimetric techniques. We observe radio sources all around the planet, organized along a high-latitude continuous auroral oval. Observations of the Hubble Space Telescope obtained in January 2004 and January 2007 have been compared to simultaneous and averaged Cassini-RPWS measurements, revealing that SKR and UV auroral ovals are very similar, both significantly enhanced on the dawnside. These results imply that the SKR and atmospheric aurorae are triggered by the same populations of energetic electron beams, requiring a unified model of particle acceleration and precipitation on Saturn.

Optical fibre sensors for the monitoring of a microwave plasma UV lamp and ozone generation system

NASA Astrophysics Data System (ADS)

O'Keeffe, S.; Ortoneda, M.; Cullen, J. D.; Shaw, A.; Fitzpatrick, C.; Lewis, E.; Phipps, D. A.; Al-Shamma'a, A. I.

2008-09-01

The food industry is keen to have new techniques that improve the safety and shelf life of food products without the use of preservatives. The use of UV light and ozone (O3) gas are becoming increasingly popular as methods to decontaminate food and thus extending its shelf life. A microwave radiation device that is a novel source of both germicidal UV and O3 suitable for the food industry has been developed, which offers speed, cost and energy benefits over existing sources. With this system comes the need to monitor a number of conditions, primarily UV intensity and ozone gas concentrations. An optical fibre sensor system is being developed to analyse these properties, in order to control and optimise the outputs of the microwave plasma UV lamp.

Polarized vacuum ultraviolet and X-radiation

NASA Technical Reports Server (NTRS)

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.

Combined corona discharge and UV photoionization source for ion mobility spectrometry.

PubMed

Bahrami, Hamed; Tabrizchi, Mahmoud

2012-08-15

An ion mobility spectrometer is described which is equipped with two non-radioactive ion sources, namely an atmospheric pressure photoionization and a corona discharge ionization source. The two sources cannot only run individually but are additionally capable of operating simultaneously. For photoionization, a UV lamp was mounted parallel to the axis of the ion mobility cell. The corona discharge electrode was mounted perpendicular to the UV radiation. The total ion current from the photoionization source was verified as a function of lamp current, sample flow rate, and drift field. Simultaneous operation of the two ionization sources was investigated by recording ion mobility spectra of selected samples. The design allows one to observe peaks from either the corona discharge or photoionization individually or simultaneously. This makes it possible to accurately compare peaks in the ion mobility spectra from each individual source. Finally, the instrument's capability for discriminating two peaks appearing in approximately identical drift times using each individual ionization source is demonstrated. Copyright © 2012 Elsevier B.V. All rights reserved.

EXPERIMENTS - APOLLO 17

NASA Image and Video Library

1972-11-17

S72-53470 (November 1972) --- The Far-Ultraviolet Spectrometer, Experiment S-169, one of the lunar orbital science experiments which will be mounted in the SIM bay of the Apollo 17 Service Module. Controls for activating and deactivating the experiment and for opening and closing a protective cover are located in the Command Module. Atomic composition, density and scale height for several constituents of the lunar atmosphere will be measured by the far-ultraviolet spectrometer. Solar far-UV radiation reflected from the lunar surface as well as UV radiation emitted by galactic sources also will be detected by the instrument.

The role of near infrared radiation in photoaging of the skin.

PubMed

Schroeder, Peter; Haendeler, Judith; Krutmann, Jean

2008-07-01

Infrared (IR) radiation is non-ionizing, electromagnetic radiation with wavelengths between 760 nm and 1 mm, which is further divided into IRA, IRB and IRC. IR accounts for more than half of the solar energy that reaches the human skin. While IRB and IRC do not penetrate deeply into the skin, more than 65% of IRA reaches the dermis. Human skin is increasingly exposed to IRA-radiation; most relevant sources are (i) natural solar radiation consisting of over 30% IRA, (ii) artificial IRA sources used for therapeutic or wellness purposes and (iii) artificial UV sources contaminated with IRA. As part of natural sunlight, IRA significantly contributes to extrinsic skin aging. This article reviews the cutaneous effects of IRA-radiation, the underlying molecular mechanisms and the available protective strategies.

Phenomenon of period-doubling in holographic periodic structures exposed to UV radiation

NASA Astrophysics Data System (ADS)

Gulyaev, Sergey N.; Isaev, Igor V.

2001-02-01

This paper presents the experimental study of the period- doubling phenomenon occurring during the multi-cycle processing procedure incorporating the exposure of Ag halide photoemulsion with the primary recorded holographic structure to the short-wave UV radiation, washing and drying. It is suggested that the simultaneous presence of two contrary photochemical processes -- photodecomposition and radiation hardening in the gelatin results in instability of the primary holographic structure and in the formation of the spatial subharmonic of the surface relief. The phenomenon may be considered as a process of the self-organization initiated by instability of the macrostructure on a rearrangement of the microstructure on the molecule level. The period-doubling phenomenon has been found to occur in the experiments with the UV sources of a various spectral composition -- the mercury- vapor lamp and the excimer lamps operating on the mixtures of Xe+Cl2 and Kr+Cl2.

Simulation of the UV-radiation at the Martian surface

NASA Astrophysics Data System (ADS)

Kolb, C.; Stimpfl, P.; Krenn, H.; Lammer, H.; Kargl, G.; Abart, R.; Patel, M. R.

The UV-radiation at the Martian surface is for several reasons of importance. UV radiation can cause specific damages in the DNA-containing living systems and is involved in the formation of catalytically produced oxidants such as superoxide ions and peroxides. These are capable to oxidize and subsequently destroy organic matter. Lab simulations are necessary to investigate and understand the effects of organic matter removal at the Martian surface. We designed a radiation apparatus which simulates the solar spectrum at the Martian surface between 200 and 700 nm. The system consists of an UV-enhanced xenon arc lamp and special exchangeable filter-sets and mirrors for simulating the effects of the Martian atmospheric column and dust loading. A special collimating system bundles the final parallel beam so that the intensity at the target spot is independent from the distance between the ray source and the sample. The system was calibrated by means of an optical photo-spectrometer to align the ray output with the theoretical target spectrum and to ensure spectral homogeneity. We present preliminary data on calibration and performance of our system, which is integrated in the Austrian Mars simulation facility.

Free-Free Radiation Cannot Make the UV/Soft-X-Ray Excess in AGN

NASA Astrophysics Data System (ADS)

Kriss, G. A.

1994-05-01

Thermal gas always has associated atomic spectral features either in absorption or in emission. In optically thin gas the emission spectrum is dominated by line radiation and recombination continua. An example of radiation from optically thin material in accreting systems is the emission-line-dominated spectrum of a cataclysmic variable in its low state. Barvainis (1993, ApJ, 412, 513) and others have proposed that the UV/soft-X-ray excess prominent in the spectra of many AGN is due to free-free emission from gas at temperatures of 10(5) - 10(6) K. Simple arguments using only atomic data show that the recombination radiation from emission lines would produce UV, optical, and soft X-ray spectral features orders of magnitude stronger than observed. Collisional excitation produces even more line radiation under most physical conditions. As a particular example I take the Astro-1 observations of the Seyfert 1 galaxy Mrk 335 by HUT and BBXRT. Depending on the ionization state of the gas (which may be photoionized by the central source), the emission measure of the free-free radiation necessary to produce the UV continuum (3 times 10(68) cm(-3) at 8.2 times 10(5) K for H_o = 75 km s(-1) Mpc(-1) ) implies line emission from O VI, O VII, or O VIII more than a factor of 10 stronger than any features observed by HUT or BBXRT.

Radiative transfer and radiative driving of outflows in active galactic nuclei and starbursts

NASA Astrophysics Data System (ADS)

Novak, G. S.; Ostriker, J. P.; Ciotti, L.

2012-12-01

To facilitate the study of black hole fuelling, star formation and feedback in galaxies, we outline a method for treating the radial forces on interstellar gas due to absorption of photons by dust grains. The method gives the correct behaviour in all of the relevant limits [dominated by the central point source; dominated by the distributed isotropic source; optically thin; optically thick to ultraviolet (UV)/optical; optically thick to infrared (IR)] and reasonably interpolates between the limits when necessary. The method is explicitly energy conserving so that UV/optical photons that are absorbed are not lost, but are rather redistributed to the IR where they may scatter out of the galaxy. We implement the radiative transfer algorithm in a two-dimensional hydrodynamical code designed to study feedback processes in the context of early-type galaxies. We find that the dynamics and final state of simulations are measurably but only moderately affected by radiative forces on dust, even when assumptions about the dust-to-gas ratio are varied from zero to a value appropriate for the Milky Way. In simulations with high gas densities designed to mimic ultraluminous IR galaxies with a star formation rate of several hundred solar masses per year, dust makes a more substantial contribution to the dynamics and outcome of the simulation. We find that, despite the large opacity of dust to UV radiation, the momentum input to the flow from radiation very rarely exceeds L/c due to two factors: the low opacity of dust to the re-radiated IR and the tendency for dust to be destroyed by sputtering in hot gas environments. We also develop a simplification of our radiative transfer algorithm that respects the essential physics but is much easier to implement and requires a fraction of the computational cost.

Glacial influences on solar radiation in a subarctic sea.

PubMed

Barron, Mace G; Barron, Kyle J

2005-01-01

Understanding macroscale processes controlling solar radiation in marine systems will be important in interpreting the potential effects of global change from increasing ultraviolet radiation (UV) and glacial retreat. This study provides the first quantitative assessment of UV in the water column of Prince William Sound, a subarctic, semienclosed sea surrounded by mountains, glaciers, rivers, bays and fjords in south central Alaska. Glacial influences on diffuse attenuation coefficients (Kd) were determined along an approximate 120 km transect running NE (61 degrees 07'43''N, 146 degrees 17'1''W) to SW (60 degrees 27'25''N, 148 degrees 05'27'' W). Glacial meltwater and flour caused a 10-fold increase in Kd for visible light, UV-A and UV-B, whereas high optical clarity was present in a diversity of areas away from glacial influences. Transition areas and locations affected by calving of a tidewater glacier had intermediate Kd values. Depths at 99% attenuation ranged from less than 0.2 m near glacial streams to greater than 5 m in bays and open ocean distant from sources of glacial sediments. These results suggest that potential global change from increasing UV and glacial retreat may have heterogeneous effects on subarctic marine systems.

Solar UV Radiation and the Origin of Life On Earth

NASA Technical Reports Server (NTRS)

Heap, S. R.; Lanz, T.; Hubeny, I.; Gaidos, E.; Oegerle, William R. (Technical Monitor)

2002-01-01

We have embarked on a program aimed at understanding the atmosphere of the early Earth, because of its importance as a greenhouse, radiation shield and energy source for life. Here, we give a progress report on the first phase of this program to establish the UV radiation from the early Sun. We have obtained ultraviolet spectra (STIS, FUSE, EUVE) of carefully selected nearby, young solar-type stars, which act as surrogates for the early Sun We are making detailed non-LTE analyses of the spectra and constructing models of their photospheres + chromospheres. Once validated, these models will allow us to extrapolate our theoretical spectra to other metallicities and to unobserved spectral regions.

New bactericidal UV light sources: excilamps

NASA Astrophysics Data System (ADS)

Sosnin, Edward A.; Lavrent'eva, Larisa V.; Erofeev, Mikhail V.; Masterova, Yana V.; Kuznetzova, Eugenia N.; Tarasenko, Victor F.

2004-05-01

A reliable bactericidal effect on Escherichia coli cells irradiation by excilamps has been established. Both on primary and secondary irradiation there exists the reciprocally proportional dependence between irradiation doze (or exposure time) and survived cells number. The microorganisms survived after primary irradiation are shown to have not changed sensitivity to excilamps irradiation. The best results have been obtained during XeBr-excilamp irradiation. Owing to their technical parameters, the excilamps are promising systems for UV-sterilization. Comparison of capacitive discharge excilamp characteristics with other conventional UV light sources in presented. A comparative study on UV doze effect of a barrier discharge KrCl-excilamp (λ = 222 nm) on Staphylococcus aureus and Escherichia coli inactivation was carried out. KrCl-excilamp emission power is 65 W, and emitting area is 0.1 m2. It has been demonstrated that Staphylococcus aureus cell sensitivity to UV radiation at this wavelength is higher than that of Escherichia coli.

UV-C radiation increases sterol production in the microalga Pavlova lutheri.

PubMed

Ahmed, Faruq; Schenk, Peer M

2017-07-01

Plant sterols have become well-known to promote cardiovascular health through the reduction of low density lipoprotein cholesterol in the blood. Plant sterols also have anti-inflammatory, anti-cancer, anti-oxidative and anti-atherogenicity activities. Microalgae have the potential to become a useful alternative source of plant sterols with several species reported to have higher concentrations than current commercial ones. In order to increase phytosterol production and optimise culture conditions, the high sterol producer Pavlova lutheri was treated in different dosages (50-250 mJ m -2 ) of UV-C radiation and several concentrations (1-500 μmol/L) of hydrogen peroxide (H 2 O 2 ) and the sterol contents were quantified for two days after the treatments. The contents of malondialdehyde (MDA) superoxide dismutase (SOD) as indications of cell membrane damage by lipid peroxidation and repair of oxidative stress, respectively, were measured. Higher activities of SOD and MDA were observed in the treated biomass when compared to the controls. Total sterols increased in P. lutheri due to UV-C radiation (at 100 mJ m -2 ) but not in response to H 2 O 2 treatment. Among the nineteen sterol compounds identified in P. lutheri, poriferasterol, epicampesterol, methylergostenol, fungisterol, dihydrochondrillasterol, and chondrillasterol increased due to UV-C radiation. Therefore, UV-C radiation can be a useful tool to boost industrial phytosterol production from P. lutheri. Copyright © 2017 Elsevier Ltd. All rights reserved.

Developmental reprogramming by UV-B radiation in plants.

PubMed

Dotto, Marcela; Casati, Paula

2017-11-01

Plants are extremely plastic organisms with the ability to adapt and respond to the changing environmental conditions surrounding them. Sunlight is one of the main resources for plants, both as a primary energy source for photosynthesis and as a stimulus that regulates different aspects of their growth and development. UV-B comprises wavelengths that correspond to a high energy region of the solar spectrum capable of reaching the biosphere, influencing plant growth. It is currently believed that plants are able to acclimate when growing under the influence of this radiation and perceive it as a signal, without stress signs. Nonetheless, many UV-B induced changes are elicited after DNA damage occurs as a consequence of exposure. In this review we focus on the influence of UV-B on leaf, flower and root development and emphasize the limited understanding of the molecular mechanisms for most of this developmental processes affected by UV-B documented over the years of research in this area. Copyright © 2017 Elsevier B.V. All rights reserved.

Photooxidation of carbofuran by a polychromatic UV irradiation without and with hydrogen peroxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benitez, F.J.; Beltran-Heredia, J.; Gonzalez, T.

The photodegradation of carbofuran aqueous solutions has been conducted with direct photolysis provided by a polychromatic UV radiation source and by the combination of this UV radiation with hydrogen peroxide. In both processes, the decomposition level obtained as a function of the operating variables is reported, and the presence of tert-butyl alcohol, a scavenger of free radicals, is discussed. While the contribution of hydroxyl radicals is negligible in the direct photolysis, its reactions in the UV/H{sub 2}O{sub 2} system clearly increase the carbofuran decomposition and therefore must be taken into account in the reaction rate equation for the total degradation.more » From the mechanisms proposed, the quantum yields for the direct photolysis and the kinetic constants for the reaction between carbofuran and the hydroxyl radicals generated in the H{sub 2}O{sub 2} photolysis in the combined process are respectively evaluated.« less

The potential carcinogenic risk of tanning beds: clinical guidelines and patient safety advice.

PubMed

Mogensen, Mette; Jemec, Gregor Be

2010-10-28

In 2009, the WHO listed ultraviolet (UV) radiation as a group 1 carcinogen. In spite of this, each year, millions of people tan indoor in Western countries. The aim of this review is to summarize evidence of tanning bed carcinogenesis and to present guidelines for use of tanning beds and patient safety advice. A narrative review of the literature was conducted based on both PubMed and Medline searches and on literature review of the retrieved papers. Use of indoor tanning beds represents a significant and avoidable risk factor for the development of both melanoma and nonmelanoma skin cancers. Frequent tanners are more often adolescent females. Tanning beds have additional potential adverse effects such as burns, solar skin damage, infection, and possibly also addictive behavior. The effort in preventing UV light-induced carcinogenesis should currently be aimed at developing new strategies for public health information. Tanning beds are one preventable source of UV radiation. In the majority of people solar UV radiation continues to be the major factor and therefore anti-tanning campaigns must always include sunbathers.

The potential carcinogenic risk of tanning beds: clinical guidelines and patient safety advice

PubMed Central

Mogensen, Mette; Jemec, Gregor BE

2010-01-01

Introduction: In 2009, the WHO listed ultraviolet (UV) radiation as a group 1 carcinogen. In spite of this, each year, millions of people tan indoor in Western countries. The aim of this review is to summarize evidence of tanning bed carcinogenesis and to present guidelines for use of tanning beds and patient safety advice. Methods: A narrative review of the literature was conducted based on both PubMed and Medline searches and on literature review of the retrieved papers. Results: Use of indoor tanning beds represents a significant and avoidable risk factor for the development of both melanoma and nonmelanoma skin cancers. Frequent tanners are more often adolescent females. Tanning beds have additional potential adverse effects such as burns, solar skin damage, infection, and possibly also addictive behavior. Discussion: The effort in preventing UV light-induced carcinogenesis should currently be aimed at developing new strategies for public health information. Tanning beds are one preventable source of UV radiation. In the majority of people solar UV radiation continues to be the major factor and therefore anti-tanning campaigns must always include sunbathers. PMID:21188119

Comparison of femtosecond laser and continuous wave UV sources for protein-nucleic acid crosslinking.

PubMed

Fecko, Christopher J; Munson, Katherine M; Saunders, Abbie; Sun, Guangxing; Begley, Tadhg P; Lis, John T; Webb, Watt W

2007-01-01

Crosslinking proteins to the nucleic acids they bind affords stable access to otherwise transient regulatory interactions. Photochemical crosslinking provides an attractive alternative to formaldehyde-based protocols, but irradiation with conventional UV sources typically yields inadequate product amounts. Crosslinking with pulsed UV lasers has been heralded as a revolutionary technique to increase photochemical yield, but this method had only been tested on a few protein-nucleic acid complexes. To test the generality of the yield enhancement, we have investigated the benefits of using approximately 150 fs UV pulses to crosslink TATA-binding protein, glucocorticoid receptor and heat shock factor to oligonucleotides in vitro. For these proteins, we find that the quantum yields (and saturating yields) for forming crosslinks using the high-peak intensity femtosecond laser do not improve on those obtained with low-intensity continuous wave (CW) UV sources. The photodamage to the oligonucleotides and proteins also has comparable quantum yields. Measurements of the photochemical reaction yields of several small molecules selected to model the crosslinking reactions also exhibit nearly linear dependences on UV intensity instead of the previously predicted quadratic dependence. Unfortunately, these results disprove earlier assertions that femtosecond pulsed laser sources provide significant advantages over CW radiation for protein-nucleic acid crosslinking.

Desired response to phototherapy vs photoaggravation in psoriasis: what makes the difference?

PubMed

Wolf, Peter; Weger, Wolfgang; Patra, VijayKumar; Gruber-Wackernagel, Alexandra; Byrne, Scott N

2016-12-01

Psoriasis commonly responds beneficially to UV radiation from natural sunlight or artificial sources. Therapeutic mechanisms include the proapoptotic and immunomodulating effects of UV, affecting many cells and involving a variety of pro- and anti-inflammatory cytokines, downregulating the Th17/IL-23 response with simultaneous induction of regulatory immune cells. However, exposure to UV radiation in a subset of psoriasis patients leads to exacerbation of the disease. We herein shed light on the predisposing factors of photosensitive psoriasis, including genetics (such as HLA-Cw*0602 or CARD14), gender and coexisting photodermatoses such as polymorphic light eruption (PLE) in the context of potential molecular mechanisms behind therapeutic photoresponsiveness or photoaggravation. UV-induced damage/pathogen-associated molecular patterns, damage to self-coding RNA (signalling through Toll-like receptors), certain antimicrobial peptides and/or inflammasome activation may induce innate immunity, leading to psoriasis at the site of UV exposure when there is concomitant, predisposing resistance against UV-induced suppression of the adaptive immune response (like in PLE) that otherwise would act to reduce psoriasis. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Study of The Non-linear Uv Dosimetry In Simulated Extraterrestrial Conditions

NASA Astrophysics Data System (ADS)

Berces, A.; Kerekgyarto, T.; Ronto, G.; Lammer, H.; Kargl, G.; Komle, N. I.

In UV biological dosimetry the UV dose scale is additive starting at a value of zero ac- cording to the definition of CIE (Technical Report TC-6-18). The biological dose can be defined by a measured end-effect. In our dosimeters (phage T7 and uracil dosime- ter) exposed to natural (terrestrial) UV radiation the proportion of pyrimidin photo- products among the total photoproducts is smaller than 10 and the linear correlation between the biological and physical dose is higher than 0.9. According to the experi- mental data this linear relationship is often not valid. We observed that UV radiation did not only induce dimerisation but shorter wavelengths caused monomerisation of pyrimidin dimers. Performing the irradiation in oxygen free environment and using a Deuterium lamp as UV source, we could increase monomerisation against dimerisa- tion thus the DNA-based dosimetrySs additivity rule is not fulfilled in these conditions. In this study we will demonstrate those non-linear experiments which constitute the basis of our biological experiments on the International Space Station.

Condenser for extreme-UV lithography with discharge source

DOEpatents

Sweatt, William C.; Kubiak, Glenn D.

2001-01-01

Condenser system, for use with a ringfield camera in projection lithography, employs quasi grazing-incidence collector mirrors that are coated with a suitable reflective metal such as ruthenium to collect radiation from a discharge source to minimize the effect of contaminant accumulation on the collecting mirrors.

Electric discharge in water as a source of UV radiation, ozone and hydrogen peroxide

NASA Astrophysics Data System (ADS)

Anpilov, A. M.; Barkhudarov, E. M.; Bark, Yu B.; Zadiraka, Yu V.; Christofi, M.; Kozlov, Yu N.; Kossyi, I. A.; Kop'ev, V. A.; Silakov, V. P.; Taktakishvili, M. I.; Temchin, S. M.

2001-03-01

Results are presented from investigations of multispark electric discharge in water excited along multielectrode metal-dielectric systems with gas supply into the interelectrode gaps. The intensity distribution of discharge radiation in the region covering the biologically active soft UV (190≤λ≤430 nm) has been determined and the absolute number of quanta in this wavelength interval has been measured. The potentiality of the slipping surface discharge in water for its disinfection is analysed. The energy expenditure for water cleansing is estimated to be as low as ~10-4 kWh l-1.

Improving radiation data quality of USDA UV-B monitoring and research program and evaluating UV decomposition in DayCent and its ecological impacts

NASA Astrophysics Data System (ADS)

Chen, Maosi

Solar radiation impacts many aspects of the Earth's atmosphere and biosphere. The total solar radiation impacts the atmospheric temperature profile and the Earth's surface radiative energy budget. The solar visible (VIS) radiation is the energy source of photosynthesis. The solar ultraviolet (UV) radiation impacts plant's physiology, microbial activities, and human and animal health. Recent studies found that solar UV significantly shifts the mass loss and nitrogen patterns of plant litter decomposition in semi-arid and arid ecosystems. The potential mechanisms include the production of labile materials from direct and indirect photolysis of complex organic matters, the facilitation of microbial decomposition with more labile materials, and the UV inhibition of microbes' population. However, the mechanisms behind UV decomposition and its ecological impacts are still uncertain. Accurate and reliable ground solar radiation measurements help us better retrieve the atmosphere composition, validate satellite radiation products, and simulate ecosystem processes. Incorporating the UV decomposition into the DayCent biogeochemical model helps to better understand long-term ecological impacts. Improving the accuracy of UV irradiance data is the goal of the first part of this research and examining the importance of UV radiation in the biogeochemical model DayCent is the goal of the second part of the work. Thus, although the dissertation is separated into two parts, accurate UV irradiance measurement links them in what follows. In part one of this work the accuracy and reliability of the current operational calibration method for the (UV-) Multi-Filter Rotating Shadowband Radiometer (MFRSR), which is used by the U.S. Department of Agriculture UV-B Monitoring and Research Program (UVMRP), is improved. The UVMRP has monitored solar radiation in the 14 narrowband UV and VIS spectral channels at 37 sites across U.S. since 1992. The improvements in the quality of the data result from an improved cloud screening algorithm that utilizes an iterative rejection of cloudy points based on a decreasing tolerance of unstable optical depth behavior when calibration information is unknown. A MODTRAN radiative transfer model simulation showed the new cloud screening algorithm was capable of screening cloudy points while retaining clear-sky points. The comparison results showed that the cloud-free points determined by the new cloud screening algorithm generated significantly (56%) more and unbiased Langley offset voltages (VLOs) for both partly cloudy days and sunny days at two testing sites, Hawaii and Florida. The V¬LOs are proportional to the radiometric sensitivity. The stability of the calibration is also improved by the development of a two-stage reference channel calibration method for collocated UV-MFRSR and MFRSR instruments. Special channels where aerosol is the only contributor to total optical depth (TOD) variation (e.g. 368-nm channel) were selected and the radiative transfer model (MODTRAN) used to calculate direct normal and diffuse horizontal ratios which were used to evaluate the stability of TOD in cloud-free points. The spectral dependence of atmospheric constituents' optical properties and previously calibrated channels were used to find stable TOD points and perform Langley calibration at spectrally adjacent channels. The test of this method on the UV-B program site at Homestead, Florida (FL02) showed that the new method generated more clustered and abundant VLOs at all (UV-) MFRSR channels and potentially improved the accuracy by 2-4% at most channels and over 10% at 300-nm and 305-nm channels. In the second major part of this work, I calibrated the DayCent-UV model with ecosystem variables (e.g. soil water, live biomass), allowed maximum photodecay rate to vary with litter's initial lignin fraction in the model, and validated the optimized model with LIDET observation of remaining carbon and nitrogen at three semi-arid sites. I also explored the ecological impacts of UV decomposition with the optimized DayCent-UV model. The DayCent-UV model showed significant better performance compared to models without UV decomposition in simulating the observed linear carbon loss pattern and the persistent net nitrogen mineralization in the 10-year LIDET experiment at the three sites. The DayCent-UV equilibrium model runs showed that UV decomposition increased aboveground and belowground plant production, surface net nitrogen mineralization, and surface litter nitrogen pool, while decreased surface litter carbon, soil net nitrogen mineralization and mineral soil carbon and nitrogen. In addition, UV decomposition showed minimal impacts (i.e. less than 1% change) on trace gases emission and biotic decomposition rates. Overall, my dissertation provided a comprehensive solution to improve the calibration accuracy and reliability of MFRSR and therefore the quality of radiation products. My dissertation also improved the understanding of UV decomposition and its long-term ecological impacts.

Repetitively pulsed UV radiation source based on a run-away electron preionised diffuse discharge in nitrogen

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baksht, E Kh; Burachenko, A G; Lomaev, M I

2015-04-30

An extended repetitively pulsed source of spontaneous UV radiation is fabricated, which may also be used for producing laser radiation. Voltage pulses with an incident wave amplitude of up to 30 kV, a half-amplitude duration of ∼4 ns and a rise time of ∼2.5 ns are applied to a gap with a nonuniform electric field. For an excitation region length of 35 cm and a nitrogen pressure of 30 – 760 Torr, a diffusive discharge up to a pulse repetition rate of 2 kHz is produced without using an additional system for gap preionisation. An investigation is made of themore » plasma of the run-away electron preionised diffuse discharge. Using a CCD camera it is found that the dense diffused plasma fills the gap in a time shorter than 1 ns. X-ray radiation is recorded from behind the foil anode throughout the pressure range under study; a supershort avalanche electron beam is recorded by the collector electrode at pressures below 100 Torr. (laser applications and other topics in quantum electronics)« less

Spectral properties of plant leaves pertaining to urban landscape design of broad-spectrum solar ultraviolet radiation reduction

NASA Astrophysics Data System (ADS)

Yoshimura, Haruka; Zhu, Hui; Wu, Yunying; Ma, Ruijun

2010-03-01

Human exposure to harmful ultraviolet (UV) radiation has important public health implications. Actual human exposure to solar UV radiation depends on ambient UV irradiance, and the latter is influenced by ground reflection. In urban areas with higher reflectivity, UV exposure occurs routinely. To discover the solar UV radiation regulation mechanism of vegetation, the spectral reflectance and transmittance of plant leaves were measured with a spectrophotometer. Typically, higher plants have low leaf reflectance (around 5%) and essentially zero transmittance throughout the UV region regardless of plant species and seasonal change. Accordingly, incident UV radiation decreases to 5% by being reflected and is reduced to zero by passing through a leaf. Therefore, stratified structures of vegetation are working as another terminator of UV rays, protecting whole terrestrial ecosystems, while vegetation at waterfronts contributes to protect aquatic ecosystems. It is possible to protect the human population from harmful UV radiation by urban landscape design of tree shade and the botanical environment. Even thin but uniformly distributed canopy is effective in attenuating UV radiation. To intercept diffuse radiation, UV screening by vertical structures such as hedges should be considered. Reflectivity of vegetation is around 2%, as foliage surfaces reduce incident UV radiation via reflection, while also eliminating it by transmittance. Accordingly, vegetation reduces incident UV radiation to around 2% by reflection. Vegetation influence on ambient UV radiation is broad-spectrum throughout the UV region. Only trees provide cool UV protective shade. Urban landscapes aimed at abating urban heat islands integrated with a reduction of human UV over-exposure would contribute to mitigation of climate change.

Tolerance to Ultraviolet Radiation of Psychrotolerant Yeasts and Analysis of Their Carotenoid, Mycosporine, and Ergosterol Content.

PubMed

Villarreal, Pablo; Carrasco, Mario; Barahona, Salvador; Alcaíno, Jennifer; Cifuentes, Víctor; Baeza, Marcelo

2016-01-01

Yeasts colonizing the Antarctic region are exposed to a high ultraviolet radiation evolving mechanisms to minimize the UV radiation damages, such as the production of UV-absorbing or antioxidant compounds like carotenoid pigments and mycosporines. Ergosterol has also been suggested to play a role in this response. These compounds are also economically attractive for several industries such as pharmaceutical and food, leading to a continuous search for biological sources of them. In this work, the UV-C radiation tolerance of yeast species isolated from the sub-Antarctic region and their production of carotenoids, mycosporines, and ergosterol were evaluated. Dioszegia sp., Leuconeurospora sp. (T27Cd2), Rhodotorula laryngis, Rhodotorula mucilaginosa, and Cryptococcus gastricus showed the highest UV-C radiation tolerance. The yeasts with the highest content of carotenoids were Dioszegia sp. (OHK torulene), Rh. laryngis (torulene and lycopene), Rh. mucilaginosa, (torulene, gamma carotene, and lycopene), and Cr. gastricus (2-gamma carotene). Probable mycosporine molecules and biosynthesis intermediates were found in Rh. laryngis, Dioszegia sp., Mrakia sp., Le. creatinivora, and Leuconeurospora sp. (T27Cd2). Ergosterol was the only sterol detected in all yeasts, and M. robertii and Le. creatinivora showed amounts higher than 4 mg g−1. Although there was not a well-defined relation between UV-C tolerance and the production of these three kinds of compounds, the majority of the yeasts with lower amounts of carotenoids showed lower UV-C tolerance. Dioszegia sp., M. robertii, and Le. creatinivora were the greatest producers of carotenoids, ergosterol, and mycosporines, respectively, representing good candidates for future studies intended to increase their production for large-scale applications.

Device and method for determining oxygen concentration and pressure in gases

DOEpatents

Ayers, Michael R.; Hunt, Arlon J.

1999-01-01

Disclosed are oxygen concentration and/or pressure sensing devices and methods which incorporate photoluminescent silica aerogels. Disclosed sensors include a light proof housing for holding the photoluminescent aerogel, a source of excitation radiation (e.g., a UV source), a detector for detecting radiation emitted by the aerogel, a system for delivering a sample gas to the aerogel, and a thermocouple. Also disclosed are water resistant oxygen sensors having a photoluminescent aerogel coated with a hydrophobic material.

X-Ray Brightening and UV Fading of Tidal Disruption Event ASASSN-15oi

NASA Astrophysics Data System (ADS)

Gezari, S.; Cenko, S. B.; Arcavi, I.

2017-12-01

We present late-time observations by Swift and XMM-Newton of the tidal disruption event (TDE) ASASSN-15oi that reveal that the source brightened in the X-rays by a factor of ∼10 one year after its discovery, while it faded in the UV/optical by a factor of ∼100. The XMM-Newton observations measure a soft X-ray blackbody component with {{kT}}{bb}∼ 45 {eV}, corresponding to radiation from several gravitational radii of a central ∼ {10}6 {M}ȯ black hole. The last Swift epoch taken almost 600 days after discovery shows that the X-ray source has faded back to its levels during the UV/optical peak. The timescale of the X-ray brightening suggests that the X-ray emission could be coming from delayed accretion through a newly forming debris disk and that the prompt UV/optical emission is from the prior circularization of the disk through stream–stream collisions. The lack of spectral evolution during the X-ray brightening disfavors ionization breakout of a TDE “veiled” by obscuring material. This is the first time a TDE has been shown to have a delayed peak in soft X-rays relative to the UV/optical peak, which may be the first clear signature of the real-time assembly of a nascent accretion disk, and provides strong evidence for the origin of the UV/optical emission from circularization, as opposed to reprocessed emission of accretion radiation.

Monitoring the High-Energy Radiation Environment of Exoplanets Around Low-mass Stars with SPARCS (Star-Planet Activity Research CubeSat)

NASA Astrophysics Data System (ADS)

Shkolnik, Evgenya L.; Ardila, David; Barman, Travis; Beasley, Matthew; Bowman, Judd D.; Gorjian, Varoujan; Jacobs, Daniel; Jewell, April; Llama, Joe; Meadows, Victoria; Nikzad, Shouleh; Scowen, Paul; Swain, Mark; Zellem, Robert

2018-01-01

Roughly seventy-five billion M dwarfs in our galaxy host at least one small planet in the habitable zone (HZ). The stellar ultraviolet (UV) radiation from M dwarfs is strong and highly variable, and impacts planetary atmospheric loss, composition and habitability. These effects are amplified by the extreme proximity of their HZs (0.1–0.4 AU). Knowing the UV environments of M dwarf planets will be crucial to understanding their atmospheric composition and a key parameter in discriminating between biological and abiotic sources for observed biosignatures. The Star-Planet Activity Research CubeSat (SPARCS) will be a 6U CubeSat devoted to photometric monitoring of M stars in the far-UV and near-UV, measuring the time-dependent spectral slope, intensity and evolution of M dwarf stellar UV radiation. For each target, SPARCS will observe continuously over at least one complete stellar rotation (5 - 45 days). SPARCS will also advance UV detector technology by flying high quantum efficiency, UV-optimized detectors developed at JPL. These Delta-doped detectors have a long history of deployment demonstrating greater than five times the quantum efficiency of the detectors used by GALEX. SPARCS will pave the way for their application in missions like LUVOIR or HabEx, including interim UV-capable missions. SPARCS will also be capable of ‘target-of-opportunity’ UV observations for the rocky planets in M dwarf HZs soon to be discovered by NASA’s TESS mission, providing the needed UV context for the first habitable planets that JWST will characterize.Acknowledgements: Funding for SPARCS is provided by NASA’s Astrophysics Research and Analysis program, NNH16ZDA001N.

Photocatalytic degradation of model textile dyes in wastewater using ZnO as semiconductor catalyst.

PubMed

Chakrabarti, Sampa; Dutta, Binay K

2004-08-30

Semiconductor photocatalysis often leads to partial or complete mineralization of organic pollutants. Upon irradiation with UV/visible light, semiconductors catalyze redox reactions in presence of air/O2 and water. Here, the potential of a common semiconductor, ZnO, has been explored as an effective catalyst for the photodegradation of two model dyes: Methylene Blue and Eosin Y. A 16 W lamp was the source of UV-radiation in a batch reactor. The effects of process parameters like, catalyst loading, initial dye concentration, airflow rate, UV-radiation intensity, and pH on the extent of photo degradation have been investigated. Substantial reduction of COD, besides removal of colour, was also achieved. A rate equation for the degradation based on Langmuir-Hinshelwood model has been proposed.

Three operation modes of the vitamin-D-biodosimeter

NASA Astrophysics Data System (ADS)

Terenetskaya, Irina P.

2016-04-01

The original UV biodosimeter for an in situ monitoring of the vitamin-D-synthetic capacity of sunlight and/or artificial UV sources is based on the same photoreaction in vitro by which vitamin D is synthesized in human skin from initial provitamin D via photo- and thermo-induced monomolecular isomerizations. Therefore, targets for UV photons in the biodosimeter are the provitamin D molecules embedded in specially designed UV transparent and stable matrix. The dosimeter response to UV radiation is photoinduced conversion of provitamin D into previtamin D which is immediate precursor of vitamin D. Thus, biological `antirachitic' UV dose is determined by the amount of accumulated previtamin D. To follow the photoreaction course in real time three operation modes of varying complexity have been developed.

21 CFR 352.72 - General testing procedures.

Code of Federal Regulations, 2010 CFR

2010-04-01

... administered the doses of UV radiation. After UV radiation exposure from the solar simulator is completed, all... specified dosage of UV radiation, in a series of UV radiation exposures, in which the test site area is... subsites should be exposed to the varying doses of UV radiation in a randomized manner. (f) Waiting period...

Unexpected photoreactivation of Vibrio harveyi bacteria living in ionization environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alifano, P.; Tala, A.; Tredici, S. M.

2011-05-15

Bacteria undergoing environmental effects is extremely interesting for structural, mechanistic, and evolutionary implications. Luminescent bacteria that have evolved in a specific ambient have developed particular responses and their behavior can give us new suggestions on the task and production of luciferina proteins. To analyze the UV interaction under controlled laboratory conditions, we used photoluminescent bacterial strains belonging to a new species evolutionarily close to Vibrio harveyi sampled from a coastal cave with a high radon content that generates ionizing radiation. The survival of the bacterial strains was analyzed, in the light and in the dark, following a variety of genotoxicmore » treatments including UV radiation exposure. The strains were irradiated by a germicide lamp. The results demonstrated that most of the strains exhibited a low rate of survival after the UV exposure. After irradiation by visible light following the UV exposure, all strains showed a high capability of photoreactivation when grown. This capability was quite unexpected because these bacteria were sampled from a dark ambient without UV radiation. This leads us to hypothesize that the photoreactivation in these bacteria might have been evolved to repair DNA lesions also induced by different radiation sources other than UV (e.g., x-ray) and that the luminescent bacteria might use their own light emission to carry out the photoreactivation. The high capability of photoreactivation of these bacteria was also justified by the results of deconvolution. The deconvolution was applied to the emission spectra and it was able to show evidence of different light peaks. The presence of the visible peak could control the photolysis enzyme.« less

Effects of near-ultraviolet light on mutations, intragenic and intergenic recombinations in Saccharomyces cerevisiae.

PubMed

Machida, I; Saeki, T; Nakai, S

1986-03-01

The effects of far (254 nm) and near (290-350 nm) ultraviolet (UV) light on mutations, intragenic and intergenic recombinations were compared in diploid strains of Saccharomyces cerevisiae. At equivalent survival levels there was not much difference in the induction of nonsense and missense mutations between far- and near-UV radiations. However, frameshift mutations were induced more frequently by near-UV than by far-UV radiation. Near-UV radiation induced intragenic recombination (gene conversion) as efficiently as far-UV radiation and the induced levels were similar in both radiations at equitoxic doses. A strikingly higher frequency was observed for the intergenic recombination induced by near-UV radiation than by far-UV radiation when compared at equivalent survival levels. Photoreactivation reduced the frequency only slightly in far-UV induced intergenic recombination and not at all in near-UV induction. These results indicate that near-UV damage involves strand breakage in addition to pyrimidine dimers and other lesions induced, whereas far-UV damage consists largely of photoreactivable lesions, pyrimidine dimers, and near-UV induced damage is more efficient for the induction of crossing-over.

Device and method for determining oxygen concentration and pressure in gases

DOEpatents

Ayers, M.R.; Hunt, A.J.

1999-03-23

Disclosed are oxygen concentration and/or pressure sensing devices and methods which incorporate photoluminescent silica aerogels. Disclosed sensors include a light proof housing for holding the photoluminescent aerogel, a source of excitation radiation (e.g., a UV source), a detector for detecting radiation emitted by the aerogel, a system for delivering a sample gas to the aerogel, and a thermocouple. Also disclosed are water resistant oxygen sensors having a photoluminescent aerogel coated with a hydrophobic material. 6 figs.

Effects of solar UV-B radiation on aquatic ecosystems

NASA Astrophysics Data System (ADS)

Häder, D.-P.

Solar UV degrades dissolved organic carbon photolytically so that they can readily be taken up by bacterioplankton. On the other hand solar UV radiation inhibits bacterioplankton activity. Bacterioplankton productivity is far greater than previously thought and is comparable to phytoplankton primary productivity. According to the "microbial loop hypothesis," bacterioplankton is seen in the center of a food web, having a similar function to phytoplankton and protists. The penetration of UV and PAR into the water column can be measured. Marine waters show large temporal and regional differences in their concentrations of dissolved and particulate absorbing substances. A network of dosimeters (ELDONET) has been installed in Europe ranging from Abisko in Northern Sweden to Gran Canaria. Cyanobacteria are capable of fixing atmospheric nitrogen which is then made available to higher plants. The agricultural potential of cyanobacteria has been recognized as a biological fertilizer for wet soils such as in rice paddies. UV-B is known to impair processes such as growth, survival, pigmentation, motility, as well as the enzymes of nitrogen metabolism and CO 2 fixation. The marine phytoplankton represents the single most important ecosystem on our planet and produces about the same biomass as all terrestrial ecosystems taken together. It is the base of the aquatic food chain and any changes in the size and composition of phytoplankton communities will directly affect food production for humans from marine sources. Another important role of marine phytoplankton is to serve as a sink for atmospheric carbon dioxide. Recent investigations have shown a large sensitivity of most phytoplankton organisms toward solar short-wavelength ultraviolet radiation (UV-B); even at ambient levels of UV-B radiation many organisms seem to be under UV stress. Because of their requirement for solar energy, the phytoplankton dwell in the top layers of the water column. In this near-surface position phytoplankton will be exposed to solar ultraviolet radiation. This radiation has been shown to affect growth, photosynthesis, nitrogen incorporation and enzyme activity. Other targets of solar UV irradiation are proteins and pigments involved in photosynthesis. Whether or not screening pigments can be induced in phytoplankton to effectively shield the organisms from excessive UV irradiation needs to be determined. Macroalgae show a distinct pattern of vertical distribution in their habitat. They have developed mechanisms to regulate their photosynthetic activity to adapt to the changing light regime and protect themselves from excessive radiation. A broad survey was carried out to understand photosynthesis in aquatic ecosystems and the different adaptation strategies to solar radiation of ecologically important species of green, red and brown algae from the North Sea, Baltic Sea, Mediterranean, Atlantic, polar and tropical oceans. Photoinhibition was quantified by oxygen exchange and by PAM (pulse amplitude modulated) fluorescence measurements based on transient changes of chlorophyll fluorescence.

Methyl halide fluxes from tropical plants under controlled radiation and temperature regimes

NASA Astrophysics Data System (ADS)

Blei, Emanuel; Yokouchi, Yoko; Saito, Takuya; Nozoe, Susumu

2015-04-01

Methyl halides (CH3Cl, CH3Br, CH3I) contribute significantly to the halogen burden of the atmosphere and have the potential to influence the stratospheric ozone layer through their catalytic effect in the Chapman cycle. As such they have been studied over the years, and many plants and biota have been examined for their potential to act as a source of these gases. One of the potentially largest terrestrial sources identified was tropical vegetation such as tropical ferns and Dipterocarp trees. Most of these studies concentrated on the identification and quantification of such fluxes rather than their characteristics and often the chambers used in these studies were either opaque or only partially transparent to the full solar spectrum. Therefore it is not certain to which degree emissions of methyl halides are innate to the plants and how much they might vary due to radiation or temperature conditions inside the enclosures. In a separate development it had been proposed that UV-radiation could cause live plant materials to be become emitters of methane even under non-anoxic conditions. As methane is chemically very similar to methyl halides and had been proposed to be produced from methyl-groups ubiquitously found in plant cell material there is a relatively good chance that such a production mechanism would also apply to methyl halides. To test whether radiation can affect elevated emissions of methyl halides from plant materials and to distinguish this from temperature effects caused by heat build-up in chambers a set of controlled laboratory chamber enclosures under various radiation and temperature regimes was conducted on four different tropical plant species (Magnolia grandiflora, Cinnamonum camphora, Cyathea lepifera, Angiopteris lygodiifolia), the latter two of which had previously been identified as strong methyl halide emitters. Abscised leaf samples of these species were subjected to radiation treatments such UV-B, UV-A and broad spectrum radiation similar to natural sunlight without the UV-component and the emissions were compared to dark enclosures. Parallel to this temperature effects were studied in dark enclosures as well. The presentation will discuss the outcome of these experiments and what conclusions can be drawn from them.

PTB’s radiometric scales for UV and VUV source calibration based on synchrotron radiation

NASA Astrophysics Data System (ADS)

Klein, Roman; Kroth, Simone; Paustian, Wolfgang; Richter, Mathias; Thornagel, Reiner

2018-06-01

The radiant intensity of synchrotron radiation can be accurately calculated with classical electrodynamics. This primary realization of the spectral radiant intensity has been used by PTB at several electron storage rings which have been optimized to be operated as primary source standards for the calibration of transfer sources in the spectral range of UV and VUV for almost 30 years. The transfer sources are compared to the primary source standard by means of suitable wavelength-dispersive transfer stations. The spectral range covered by deuterium lamps, which represent transfer sources that are easy to handle, is of particular relevance in practice. Here, we report on developments in the realization and preservation of the radiometric scales for spectral radiant intensity and spectral radiance in the wavelength region from 116 nm to 400 nm, based on a set of deuterium reference lamps, over the last few decades. An inside view and recommendations on the operation of the D2 lamps used for the realization of the radiometric scale are presented. The data has been recently compiled to illustrate the chronological behaviour at various wavelengths. Moreover, an overview of the internal and external validation measurements and intercomparisons is given.

Solar UV-A and UV-B radiation fluxes at two Alpine stations at different altitudes

NASA Astrophysics Data System (ADS)

Blumthaler, M.; Ambach, W.; Rehwald, W.

1992-03-01

Daily totals of UV-A and UV-B radiation fluxes and global radiation were measured since 1981 at Jungfraujoch (3576 m) a.s.l.) and in Innsbruck (577 m a.s.l.) in their seasonal course. The altitude effect of annual totals yields 19%/1000 m (UV-B), 11%/1000 m (UV-A) and 9%/1000 m (global radiation) with reference to Innsbruck station. The ratio of the daily totals of UV-B/global radiation shows a significant seasonal course with the maximum in summer, whereas the ratio of the daily totals of UV-A/global radiation shows no significant seasonal variation. The biological effective doses of erythema reaction, delayed tanning and immediate tanning by UV-A and UV-B radiant exposure are reported in the seasonal course at Jungfraujoch and in Innsbruck.

Effects of urban agglomeration on surface-UV doses: a comparison of Brewer measurements in Warsaw and Belsk, Poland, for the period 2013-2015

NASA Astrophysics Data System (ADS)

Czerwińska, Agnieszka E.; Krzyścin, Janusz W.; Jarosławski, Janusz; Posyniak, Michał

2016-11-01

Specific aerosols and cloud properties over large urban regions seem to generate an island, similar to the well-known urban heat island, leading to lower ultraviolet (UV) radiation intensity compared to the surrounding less polluted areas, thus creating a shield against excessive human exposure to UV radiation. The present study focuses on differences between erythemal and UVA (324 nm) doses measured by the Brewer spectrophotometers in Warsaw (52.3° N, 21.0° E) and Belsk (51.8° N, 20.8° E). The latter is a rural region located about 60 km south-west of the city. Ratios between erythemal and UVA partly daily doses, obtained during all-sky and cloudless-sky conditions for the period May 2013-December 2015, were analysed to infer a specific cloud and aerosol forcing on the surface UV doses over Warsaw. Radiative model simulations were carried out to find sources of the observed differences between the sites. It was found that Warsaw urban agglomeration induced 8 and 6 % attenuation of the erythemal and UVA doses respectively. This is mostly due to the lower sun elevation in Warsaw during the near-noon measurements and the larger optical depth of the city aerosols and increased cloudiness. It could be hypothesised that the expected stronger absorption of the solar UV radiation by urban aerosols is compensated for here by a higher surface reflectivity over the city.

Initial application of a dual-sweep streak camera to the Duke storage ring OK-4 source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lumpkin, A.H.; Yang, B.X.; Litvinenko, V.

1997-08-01

The visible and UV spontaneous emission radiation (SER) from the Duke OK-4 wiggler has been used with a Hamamatsu C5680 dual-sweep streak camera to characterize the stored electron beams. Particle beam energies of 270 and 500 MeV in the Duke storage ring were used in this initial application with the OK-4 adjusted to generate wavelengths from 500 nm to near 200 nm. The OK-4 magnetic system with its 68 periods provided a much stronger radiation source than a nearby bending magnet source point. Sensitivity to single-bunch, single-turn SER was shown down to 4 {mu}A beam current at {lambda} = 450more » nm. The capability of seeing second passes in the FEL resonator at a wavelength near 200 nm was used to assess the cavity length versus orbit length. These tests (besides supporting preparation for UV-visible SR FEL startups) are also relevant to possible diagnostics techniques for single-pass FEL prototype facilities.« less

Solar ultraviolet radiation is necessary to enhance grapevine fruit ripening transcriptional and phenolic responses.

PubMed

Carbonell-Bejerano, Pablo; Diago, Maria-Paz; Martínez-Abaigar, Javier; Martínez-Zapater, José M; Tardáguila, Javier; Núñez-Olivera, Encarnación

2014-07-09

Ultraviolet (UV) radiation modulates secondary metabolism in the skin of Vitis vinifera L. berries, which affects the final composition of both grapes and wines. The expression of several phenylpropanoid biosynthesis-related genes is regulated by UV radiation in grape berries. However, the complete portion of transcriptome and ripening processes influenced by solar UV radiation in grapes remains unknown. Whole genome arrays were used to identify the berry skin transcriptome modulated by the UV radiation received naturally in a mid-altitude Tempranillo vineyard. UV radiation-blocking and transmitting filters were used to generate the experimental conditions. The expression of 121 genes was significantly altered by solar UV radiation. Functional enrichment analysis of altered transcripts mainly pointed out that secondary metabolism-related transcripts were induced by UV radiation including VvFLS1, VvGT5 and VvGT6 flavonol biosynthetic genes and monoterpenoid biosynthetic genes. Berry skin phenolic composition was also analysed to search for correlation with gene expression changes and UV-increased flavonols accumulation was the most evident impact. Among regulatory genes, novel UV radiation-responsive transcription factors including VvMYB24 and three bHLH, together with known grapevine UV-responsive genes such as VvMYBF1, were identified. A transcriptomic meta-analysis revealed that genes up-regulated by UV radiation in the berry skin were also enriched in homologs of Arabidopsis UVR8 UV-B photoreceptor-dependent UV-B -responsive genes. Indeed, a search of the grapevine reference genomic sequence identified UV-B signalling pathway homologs and among them, VvHY5-1, VvHY5-2 and VvRUP were up-regulated by UV radiation in the berry skin. Results suggest that the UV-B radiation-specific signalling pathway is activated in the skin of grapes grown at mid-altitudes. The biosynthesis and accumulation of secondary metabolites, which are appreciated in winemaking and potentially confer cross-tolerance, were almost specifically triggered. This draws attention to viticultural practices that increase solar UV radiation on vineyards as they may improve grape features.

Cyclotron Line in Solar Microwave Radiation by Radio Telescope RATAN-600 Observations of the Solar Active Region NOAA 12182

NASA Astrophysics Data System (ADS)

Peterova, N. G.; Topchilo, N. A.

2017-12-01

This paper presents the results of observation of a rare phenomenon—a narrowband increase in the brightness of cyclotron radiation of one of the structural details of a radio source located in the solar corona above the solar active region NOAA 12182 in October 2014 at a frequency of 4.2 ± 0.1 GHz. The brightness of radiation in the maximum of the phenomenon has reached 10 MK; its duration was equal to 3 s. The exact location of the source of the narrowband cyclotron radiation is indicated: it is a corona above a fragmented (4-nuclear) sunspot, on which a small UV flare loop was closed.

Fast simulation tool for ultraviolet radiation at the earth's surface

NASA Astrophysics Data System (ADS)

Engelsen, Ola; Kylling, Arve

2005-04-01

FastRT is a fast, yet accurate, UV simulation tool that computes downward surface UV doses, UV indices, and irradiances in the spectral range 290 to 400 nm with a resolution as small as 0.05 nm. It computes a full UV spectrum within a few milliseconds on a standard PC, and enables the user to convolve the spectrum with user-defined and built-in spectral response functions including the International Commission on Illumination (CIE) erythemal response function used for UV index calculations. The program accounts for the main radiative input parameters, i.e., instrumental characteristics, solar zenith angle, ozone column, aerosol loading, clouds, surface albedo, and surface altitude. FastRT is based on look-up tables of carefully selected entries of atmospheric transmittances and spherical albedos, and exploits the smoothness of these quantities with respect to atmospheric, surface, geometrical, and spectral parameters. An interactive site, http://nadir.nilu.no/~olaeng/fastrt/fastrt.html, enables the public to run the FastRT program with most input options. This page also contains updated information about FastRT and links to freely downloadable source codes and binaries.

UV-B Radiation Induces Root Bending Through the Flavonoid-Mediated Auxin Pathway in Arabidopsis.

PubMed

Wan, Jinpeng; Zhang, Ping; Wang, Ruling; Sun, Liangliang; Wang, Wenying; Zhou, Huakun; Xu, Jin

2018-01-01

Ultraviolet (UV)-B radiation-induced root bending has been reported; however, the underlying mechanisms largely remain unclear. Here, we investigate whether and how auxin and flavonoids are involved in UV-B radiation-induced root bending in Arabidopsis using physiological, pharmacological, and genetic approaches. UV-B radiation modulated the direction of root growth by decreasing IAA biosynthesis and affecting auxin distribution in the root tips, where reduced auxin accumulation and asymmetric auxin distribution were observed. UV-B radiation increased the distribution of auxin on the nonradiated side of the root tips, promoting growth and causing root bending. Further analysis indicated that UV-B induced an asymmetric accumulation of flavonoids; this pathway is involved in modulating the accumulation and asymmetric distribution of auxin in root tips and the subsequent redirection of root growth by altering the distribution of auxin carriers in response to UV-B radiation. Taken together, our results indicate that UV-B radiation-induced root bending occurred through a flavonoid-mediated phototropic response to UV-B radiation.

UV-B Radiation Induces Root Bending Through the Flavonoid-Mediated Auxin Pathway in Arabidopsis

PubMed Central

Wan, Jinpeng; Zhang, Ping; Wang, Ruling; Sun, Liangliang; Wang, Wenying; Zhou, Huakun; Xu, Jin

2018-01-01

Ultraviolet (UV)-B radiation-induced root bending has been reported; however, the underlying mechanisms largely remain unclear. Here, we investigate whether and how auxin and flavonoids are involved in UV-B radiation-induced root bending in Arabidopsis using physiological, pharmacological, and genetic approaches. UV-B radiation modulated the direction of root growth by decreasing IAA biosynthesis and affecting auxin distribution in the root tips, where reduced auxin accumulation and asymmetric auxin distribution were observed. UV-B radiation increased the distribution of auxin on the nonradiated side of the root tips, promoting growth and causing root bending. Further analysis indicated that UV-B induced an asymmetric accumulation of flavonoids; this pathway is involved in modulating the accumulation and asymmetric distribution of auxin in root tips and the subsequent redirection of root growth by altering the distribution of auxin carriers in response to UV-B radiation. Taken together, our results indicate that UV-B radiation-induced root bending occurred through a flavonoid-mediated phototropic response to UV-B radiation. PMID:29868074

Photochemical oxidation of persistent cyanide-related compounds

NASA Astrophysics Data System (ADS)

Budaev, S. L.; Batoeva, A. A.; Khandarkhaeva, M. S.; Aseev, D. G.

2017-03-01

Kinetic regularities of the photolysis of thiocyanate solutions using of mono- and polychromatic UV radiation sources with different spectral ranges are studied. Comparative experiments aimed at investigating the role of photochemical action during the oxidation of thiocyanates with persulfates and additional catalytic activation with iron(III) ions are performed. The rate of conversion and the initial rate of thiocyanate oxidation are found to change in the order UV < UV/S2O 8 2- < S2O 8 2- /Fe3+ < UV/S2O 8 2- /Fe3+. A synergistic effect is detected when using the combined catalytic method for the destruction of thiocyanates by the UV/S2O 8 2- /Fe3+ oxidation system. This effect is due to the formation of reactive oxygen species, as a result of both the decomposition of persulfate and the reduction of inactive Fe3+ intermediates into Fe3+.

Solar UV Radiation and the Origin of Life on Earth

NASA Technical Reports Server (NTRS)

Heap, S. R.; Gaidos, E.; Hubeny, I.; Lanz, T. M.; Fisher, Richard R. (Technical Monitor)

2001-01-01

We have embarked on a program aimed at understanding the atmosphere of the early Earth, because of its importance as a greenhouse, radiation shield, and energy source for life. Here, we give a progress report on the first phase of this program: to establish the UV radiation from the early Sun. We are presently obtaining ultraviolet spectra (STIS, FUSE, EUVE) of carefully selected nearby, young solar-type stars, which act as surrogates for the early Sun. We are currently making detailed non-LTE analyses of the spectra and constructing models of their photospheres + chromospheres. once validated, these models will allow us to extrapolate our theoretical spectra to unobserved spectral regions, and to proceed to the next step: to develop photochemical models of the pre-biotic and Archean atmosphere of the Earth.

Protective mechanisms and acclimation to solar ultraviolet-B radiation in Oenothera stricta

NASA Technical Reports Server (NTRS)

Robberecht, R.; Caldwell, M. M.

1981-01-01

Plant adaptations ameliorating or repairing the damaging effects of ultraviolet-B (UV-B) radiation on plant tissue were investigated. The degree of phenotype plasticity in UV protective mechanisms and acclimation in relation to the natural solar UV-B radiation flux and in an enhanced UV-B irradiance environment was also examined. Mechanisms by which plants avoid radiation, adaptations altering the path of radiation incident on the leaf, and repair processes were considered. Attenuation of UV-B by tissues, UV-B irradiation into the leaf, and the effects of UV-B on photosynthesis were investigated.

Elucidation of Free Radical and Optogalvanic Spectroscopy Associated with Microgravity Combustion via Conventional and Novel Laser Platforms

NASA Technical Reports Server (NTRS)

Misra, Prabhakar; She, Yong-Bo; Zhu, Xin-Ming; King, Michael

1997-01-01

Combustion studies under both normal gravity and microgravity conditions depend a great deal on the availability and quality of the diagnostic systems used for such investigations. Microgravity phenomena are specially susceptible to even small perturbations and therefore non-intrusive diagnostic techniques are of paramount importance for successful understanding of reduced-gravity combustion phenomena. Several non-intrusive diagnostic techniques are available for probing and delineating normal as well as reduced gravity combustion processes, such as Rayleigh scattering, Raman scattering, Mie scattering, velocimetry, interferometric and Schlieren techniques, emission and laser-induced fluorescence (LIF) spectroscopy. Our approach is to use the LIF technique as a non-intrusive diagnostic tool for the study of combustion-associated free radicals and use the concomitant optogalvanic transitions to accomplish precise calibration of the laser wavelengths used for recording the excitation spectra of transient molecular species. In attempting to perform spectroscopic measurements on chemical intermediates, we have used conventional laser sources as well as new and novel platforms employing rare-earth doped solid-state lasers. Conventional (commercially available) sources of tunable UV laser radiation are extremely cumbersome and energy-consuming devices that are not very suitable for either in-space or in-flight (or microgravity drop tower) experiments. Traditional LIF sources of tunable UV laser radiation involve in addition to a pump laser (usually a Nd:YAG laser with an attached frequency-doubling stage), a tunable dye laser. In turn, the dye laser has to be provided with a dye circulation system and a subsequent stage for frequency-doubling of the dye laser radiation, together with a servo-tuning system (termed the 'Autotracker') to follow the wavelength changes and also an optical system (called the 'Frequency Separator') for separation of the emanating visible and UV beams. In contrast to this approach, we have devised an alternate arrangement for recording LIF excitation spectra of free radicals (following appropriate precursor fragmentation) that utilizes a tunable rare-earth doped solid state laser system with direct UV pumping. We have designed a compact and portable tunable UV laser system incorporating features necessary for both in-space and in-flight spectroscopy experiments. For the purpose of LIF excitation, we have developed an all-solid-state tunable UV laser that employs direct pumping of the solid-state UV-active medium employing UV harmonics from a Nd:YAG laser. An optical scheme with counterpropagating photolysis and excitation beams focused by suitable lenses into a reaction vacuum chamber was employed.

Evaluation of erythemal UV effective irradiance from UV lamp exposure and the application in shield metal arc welding processing.

PubMed

Chang, Cheng-Ping; Liu, Hung-Hsin; Peng, Chiung-Yu; Fang, Hsin-Yu; Tsao, Ta-Ho; Lan, Cheng-Hang

2008-04-01

Ultraviolet radiation (UVR) exposure is known to cause potential effects such as erythema in skin. For UV-induced erythema (sunburn), the action spectrum from the Commission Internationale de l'Eclairage, International Commission on Illumination (CIE) was adopted. Erythemal UV effects from UVR lamp exposure were investigated with commercial spectroradiometry devices in this research. Three kinds of portable UV germicidal lamps with broadband UVA (BB UVA, 350-400 nm), broadband UVB (BB UVB, 280-350 nm), and narrowband UVC (NB UVC, 254 nm) wavelengths served as the UVR emission sources. An action spectrum expresses the effectiveness of radiation for assessing the hazard of UVR in the erythemal action spectrum from 250-400 nm. The UV Index (UVI) is an irradiance scale computed by multiplying the CIE erythemal irradiance integral in milliwatts per square meter by 0.04 m mW. A comprehensive approach to detecting erythemal UVR magnitude was developed to monitor the effective exposure from UV lamps. The erythemal UVR measurement was established and the exposure assessment was applied to monitor erythemal UVR magnitude from shield metal arc welding (SMAW) processing. From this study, the erythemal UVR exposures were assessed and evaluated with environmental solar simulation of the UVI exposure.

Health risks of exposure to non-ionizing radiation--myths or science-based evidence.

PubMed

Hietanen, Maila

2006-01-01

The non-ionizing radiation (NIR) contains large range of wavelengths and frequencies from vacuum ultraviolet (UV) radiation to static electric and magnetic fields. Biological effects of electromagnetic (EM) radiation depend greatly on wavelength and other physical parameters. The Sun is the most significant source of environmental UV exposure, so that outdoor workers are at risk of chronic over-exposure. Also exposure to short-wave visible light is associated with the aging and degeneration of the retina. Especially hazardous are laser beams focused to a small spot at the retina, resulting in permanent visual impairment. Exposure to EM fields induces body currents and energy absorption in tissues, depending on frequencies and coupling mechanisms. Thermal effects caused by temperature rise are basically understood, whereas the challenge is to understand the suspected non-thermal effects. Radiofrequency (RF) fields around frequencies of 900 MHz and 1800 MHz are of special interest because of the rapid advances in the telecommunication technology. The field levels of these sources are so low that temperature rise is unlikely to explain possible health effects. Other mechanisms of interaction have been proposed, but biological experiments have failed to confirm their existence.

Prevent Eye Damage: Protect Yourself from UV Radiation

MedlinePlus

... vision. ® Snow Blindness (Photokeratitis): A temporary but painful burn to the cornea caused by a day at the beach without sunglasses; reflections off of snow, water, or concrete; or exposure to artificial light sources such as ...

Ultraviolet Radiation in Wound Care: Sterilization and Stimulation

PubMed Central

Gupta, Asheesh; Avci, Pinar; Dai, Tianhong; Huang, Ying-Ying; Hamblin, Michael R.

2013-01-01

Significance Wound care is an important area of medicine considering the increasing age of the population who may have diverse comorbidities. Light-based technology comprises a varied set of modalities of increasing relevance to wound care. While low-level laser (or light) therapy and photodynamic therapy both have wide applications in wound care, this review will concentrate on the use of ultraviolet (UV) radiation. Recent Advances UVC (200–280 nm) is highly antimicrobial and can be directly applied to acute wound infections to kill pathogens without unacceptable damage to host tissue. UVC is already widely applied for sterilization of inanimate objects. UVB (280–315 nm) has been directly applied to the wounded tissue to stimulate wound healing, and has been widely used as extracorporeal UV radiation of blood to stimulate the immune system. UVA (315–400 nm) has distinct effects on cell signaling, but has not yet been widely applied to wound care. Critical Issues Penetration of UV light into tissue is limited and optical technology may be employed to extend this limit. UVC and UVB can damage DNA in host cells and this risk must be balanced against beneficial effects. Chronic exposure to UV can be carcinogenic and this must be considered in planning treatments. Future Directions New high-technology UV sources, such as light-emitting diodes, lasers, and microwave-generated UV plasma are becoming available for biomedical applications. Further study of cellular signaling that occurs after UV exposure of tissue will allow the benefits in wound healing to be better defined. PMID:24527357

Phosphorus-bearing molecules in the Galactic Center

NASA Astrophysics Data System (ADS)

Rivilla, V. M.; Jiménez-Serra, I.; Zeng, S.; Martín, S.; Martín-Pintado, J.; Armijos-Abendaño, J.; Viti, S.; Aladro, R.; Riquelme, D.; Requena-Torres, M.; Quénard, D.; Fontani, F.; Beltrán, M. T.

2018-03-01

Phosphorus (P) is one of the essential elements for life due to its central role in biochemical processes. Recent searches have shown that P-bearing molecules (in particular PN and PO) are present in star-forming regions, although their formation routes remain poorly understood. In this letter, we report observations of PN and PO towards seven molecular clouds located in the Galactic Center, which are characterized by different types of chemistry. PN is detected in five out of seven sources, whose chemistry is thought to be shock-dominated. The two sources with PN non-detections correspond to clouds exposed to intense UV/X-rays/cosmic ray (CR) radiation. PO is detected only towards the cloud G+0.693-0.03, with a PO/PN abundance ratio of ˜1.5. We conclude that P-bearing molecules likely form in shocked gas as a result of dust grain sputtering, while are destroyed by intense UV/X-ray/CR radiation.

The variation in surface morphology and hardness of human deciduous teeth samples after laser irradiation

NASA Astrophysics Data System (ADS)

Khalid, Arooj; Bashir, Shazia; Akram, Mahreen; Salman Ahmed, Qazi

2017-11-01

The variation in surface morphology and hardness of human deciduous teeth samples has been investigated after laser irradiation at different wavelengths and energies. Nd:YAG was employed as a source of irradiation for IR (1064 nm) and visible (532 nm) radiation, whereas an excimer laser was used as the source of UV (248 nm) radiation. Scanning electron microscope (SEM) analysis was carried out to reveal the surface morphological evolution of teeth samples. Vickers microhardness tester was employed to investigate the modifications in the hardness of the laser-treated samples. It is observed from SEM analysis that IR wavelength is responsible for ablation of collagen matrix and intertubular dentine. For visible radiation, the ablation of collagen along with hydroxypatite is observed. With UV radiation, the ablation of peritubular dentine is dominant and is responsible for the sealing of tubules. The decrease in hardness at lower energy for both wavelengths is due to the evaporation of carbon content. With increasing energy, evaporation of water along with carbon content, and resolidification and re-organization of inorganic content causes the increase in hardness of the treated dentine. SEM as well as microhardness analyses reveal that laser wavelengths and energy of laser radiation significantly influence the surface morphology and hardness of samples.

UV-B Radiation Contributes to Amphibian Population Declines

NASA Astrophysics Data System (ADS)

Blaustein, Andrew

2007-05-01

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

Light transmission and ultraviolet protection of contact lenses under artificial illumination.

PubMed

Artigas, José M; Navea, Amparo; García-Domene, M Carmen; Gené, Andrés; Artigas, Cristina

2016-04-01

To determine the spectral transmission of contact lenses (CLs), with and without an ultraviolet (UV) filter to evaluate their capacity for protection under UV radiation from artificial illumination (incandescent, fluorescent, xenon (Xe) lamps, or white LEDs (light-emitting diode)). The transmission curves of nine soft CLs were obtained by using a PerkinElmer Lambda 35 UV-vis spectrophotometer. A CIE standard was used for the emission spectra of incandescent and fluorescent lamps, and Xe lamps and white LEDs were measured by using an International Light Technologies ILT-950 spectroradiometer. Five of the nine soft CLs analysed state that they incorporate UV filters, but the other four do not specify anything in this regard. The spectral transmission of all the CLs studied is excellent in the visible region. The CLs with UV filters filter out this radiation more or less effectively. Xe lamps emit a part in the UV region. Incandescent, fluorescent and white LEDs do not emit at all in the UV. Incorporating UV filters is important when the illumination is from a Xe lamp since this light source emits in the UV region. This, however, does not occur with incandescent and fluorescent lamps or white LEDs. The CLs that do incorporate UV filters meet all the standard requirements that the U.S. FDA (Food and Drug Administration) has for UV-blocking CLs Class II (OcularScience, CooperVision and Neolens), and AcuvueMoist and HydronActifresh400 even comply with the stricter Class I. The CLs without UV filters let UVA, UVB and even some UVC through. Copyright © 2015. Published by Elsevier Ltd.

Exposure of vitamins to UVB and UVA radiation generates singlet oxygen.

PubMed

Knak, Alena; Regensburger, Johannes; Maisch, Tim; Bäumler, Wolfgang

2014-05-01

Deleterious effects of UV radiation in tissue are usually attributed to different mechanisms. Absorption of UVB radiation in cell constituents like DNA causes photochemical reactions. Absorption of UVA radiation in endogenous photosensitizers like vitamins generates singlet oxygen via photosensitized reactions. We investigated two further mechanisms that might be involved in UV mediated cell tissue damage. Firstly, UVB radiation and vitamins also generate singlet oxygen. Secondly, UVB radiation may change the chemical structure of vitamins that may change the role of such endogenous photosensitizers in UVA mediated mechanisms. Vitamins were irradiated in solution using monochromatic UVB (308 nm) or UVA (330, 355, or 370 nm) radiation. Singlet oxygen was directly detected and quantified by its luminescence at 1270 nm. All investigated molecules generated singlet oxygen with a quantum yield ranging from 0.007 (vitamin D3) to 0.64 (nicotinamide) independent of the excitation wavelength. Moreover, pre-irradiation of vitamins with UVB changed their absorption in the UVB and UVA spectral range. Subsequently, molecules such as vitamin E and vitamin K1, which normally exhibit no singlet oxygen generation in the UVA, now produce singlet oxygen when exposed to UVA at 355 nm. This interplay of different UV sources is inevitable when applying serial or parallel irradiation with UVA and UVB in experiments in vitro. These results should be of particular importance for parallel irradiation with UVA and UVB in vivo, e.g. when exposing the skin to solar radiation.

The Space Weather and Ultraviolet Solar Variability (SWUSV) Microsatellite Mission

PubMed Central

Damé, Luc; Meftah, Mustapha; Hauchecorne, Alain; Keckhut, Philippe; Sarkissian, Alain; Marchand, Marion; Irbah, Abdenour; Quémerais, Éric; Bekki, Slimane; Foujols, Thomas; Kretzschmar, Matthieu; Cessateur, Gaël; Shapiro, Alexander; Schmutz, Werner; Kuzin, Sergey; Slemzin, Vladimir; Urnov, Alexander; Bogachev, Sergey; Merayo, José; Brauer, Peter; Tsinganos, Kanaris; Paschalis, Antonis; Mahrous, Ayman; Khaled, Safinaz; Ghitas, Ahmed; Marzouk, Besheir; Zaki, Amal; Hady, Ahmed A.; Kariyappa, Rangaiah

2013-01-01

We present the ambitions of the SWUSV (Space Weather and Ultraviolet Solar Variability) Microsatellite Mission that encompasses three major scientific objectives: (1) Space Weather including the prediction and detection of major eruptions and coronal mass ejections (Lyman-Alpha and Herzberg continuum imaging); (2) solar forcing on the climate through radiation and their interactions with the local stratosphere (UV spectral irradiance from 180 to 400 nm by bands of 20 nm, plus Lyman-Alpha and the CN bandhead); (3) simultaneous radiative budget of the Earth, UV to IR, with an accuracy better than 1% in differential. The paper briefly outlines the mission and describes the five proposed instruments of the model payload: SUAVE (Solar Ultraviolet Advanced Variability Experiment), an optimized telescope for FUV (Lyman-Alpha) and MUV (200–220 nm Herzberg continuum) imaging (sources of variability); UPR (Ultraviolet Passband Radiometers), with 64 UV filter radiometers; a vector magnetometer; thermal plasma measurements and Langmuir probes; and a total and spectral solar irradiance and Earth radiative budget ensemble (SERB, Solar irradiance & Earth Radiative Budget). SWUSV is proposed as a small mission to CNES and to ESA for a possible flight as early as 2017–2018. PMID:25685424

The Space Weather and Ultraviolet Solar Variability (SWUSV) Microsatellite Mission.

PubMed

Damé, Luc

2013-05-01

We present the ambitions of the SWUSV (Space Weather and Ultraviolet Solar Variability) Microsatellite Mission that encompasses three major scientific objectives: (1) Space Weather including the prediction and detection of major eruptions and coronal mass ejections (Lyman-Alpha and Herzberg continuum imaging); (2) solar forcing on the climate through radiation and their interactions with the local stratosphere (UV spectral irradiance from 180 to 400 nm by bands of 20 nm, plus Lyman-Alpha and the CN bandhead); (3) simultaneous radiative budget of the Earth, UV to IR, with an accuracy better than 1% in differential. The paper briefly outlines the mission and describes the five proposed instruments of the model payload: SUAVE (Solar Ultraviolet Advanced Variability Experiment), an optimized telescope for FUV (Lyman-Alpha) and MUV (200-220 nm Herzberg continuum) imaging (sources of variability); UPR (Ultraviolet Passband Radiometers), with 64 UV filter radiometers; a vector magnetometer; thermal plasma measurements and Langmuir probes; and a total and spectral solar irradiance and Earth radiative budget ensemble (SERB, Solar irradiance & Earth Radiative Budget). SWUSV is proposed as a small mission to CNES and to ESA for a possible flight as early as 2017-2018.

Skyglow effects in UV and visible spectra: Radiative fluxes

NASA Astrophysics Data System (ADS)

Kocifaj, Miroslav; Solano Lamphar, Hector Antonio

2013-09-01

Several studies have tried to understand the mechanisms and effects of radiative transfer under different night-sky conditions. However, most of these studies are limited to the various effects of visible spectra. Nevertheless, the invisible parts of the electromagnetic spectrum can pose a more profound threat to nature. One visible threat is from what is popularly termed skyglow. Such skyglow is caused by injudiciously situated or designed artificial night lighting systems which degrade desired sky viewing. Therefore, since lamp emissions are not limited to visible electromagnetic spectra, it is necessary to consider the complete spectrum of such lamps in order to understand the physical behaviour of diffuse radiation at terrain level. In this paper, the downward diffuse radiative flux is computed in a two-stream approximation and obtained ultraviolet spectral radiative fluxes are inter-related with luminous fluxes. Such a method then permits an estimate of ultraviolet radiation if the traditionally measured illuminance on a horizontal plane is available. The utility of such a comparison of two spectral bands is shown, using the different lamp types employed in street lighting. The data demonstrate that it is insufficient to specify lamp type and its visible flux production independently of each other. Also the UV emissions have to be treated by modellers and environmental scientists because some light sources can be fairly important pollutants in the near ultraviolet. Such light sources can affect both the living organisms and ambient environment.

Sensing and Responding to UV-A in Cyanobacteria

PubMed Central

Moon, Yoon-Jung; Kim, Seung Il; Chung, Young-Ho

2012-01-01

Ultraviolet (UV) radiation can cause stresses or act as a photoregulatory signal depending on its wavelengths and fluence rates. Although the most harmful effects of UV on living cells are generally attributed to UV-B radiation, UV-A radiation can also affect many aspects of cellular processes. In cyanobacteria, most studies have concentrated on the damaging effect of UV and defense mechanisms to withstand UV stress. However, little is known about the activation mechanism of signaling components or their pathways which are implicated in the process following UV irradiation. Motile cyanobacteria use a very precise negative phototaxis signaling system to move away from high levels of solar radiation, which is an effective escape mechanism to avoid the detrimental effects of UV radiation. Recently, two different UV-A-induced signaling systems for regulating cyanobacterial phototaxis were characterized at the photophysiological and molecular levels. Here, we review the current understanding of the UV-A mediated signaling pathways in the context of the UV-A perception mechanism, early signaling components, and negative phototactic responses. In addition, increasing evidences supporting a role of pterins in response to UV radiation are discussed. We outline the effect of UV-induced cell damage, associated signaling molecules, and programmed cell death under UV-mediated oxidative stress. PMID:23208372

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

PubMed

Soriano-Melgar, Lluvia de Abril Alexandra; Alcaraz-Meléndez, Lilia; Méndez-Rodríguez, Lía C; Puente, María Esther; Rivera-Cabrera, Fernando; Zenteno-Savín, Tania

2014-05-01

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. 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. 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). 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. Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

DESIGN, CONSTRUCTION, AND EVALUATION OF A CHAMBER FOR AEROBIOLOGY

EPA Science Inventory

A chamber was designed and constructed for aeromicrobiology applications. An ultraviolet (UV) radiation source was incorporated to sterilize the chamber between trials. Twelve bacterial species originally isolated from air samples and obtained from the American Type Culture Colle...

Effects of solar UV-B radiation on aquatic ecosystems.

PubMed

Hader, D P

2000-01-01

Solar UV degrades dissolved organic carbon photolytically so that they can readily be taken up by bacterioplankton. On the other hand solar UV radiation inhibits bacterioplankton activity. Bacterioplankton productivity is far greater than previously thought and is comparable to phytoplankton primary productivity. According to the "microbial loop hypothesis," bacterioplankton is seen in the center of a food web, having a similar function to phytoplankton and protists. The penetration of UV and PAR into the water column can be measured. Marine waters show large temporal and regional differences in their concentrations of dissolved and particulate absorbing substances. A network of dosimeters (ELDONET) has been installed in Europe ranging from Abisko in Northern Sweden to Gran Canaria. Cyanobacteria are capable of fixing atmospheric nitrogen which is then made available to higher plants. The agricultural potential of cyanobacteria has been recognized as a biological fertilizer for wet soils such as in rice paddies. UV-B is known to impair processes such as growth, survival, pigmentation, motility, as well as the enzymes of nitrogen metabolism and CO2 fixation. The marine phytoplankton represents the single most important ecosystem on our planet and produces about the same biomass as all terrestrial ecosystems taken together. It is the base of the aquatic food chain and any changes in the size and composition of phytoplankton communities will directly affect food production for humans from marine sources. Another important role of marine phytoplankton is to serve as a sink for atmospheric carbon dioxide. Recent investigations have shown a large sensitivity of most phytoplankton organisms toward solar short-wavelength ultraviolet radiation (UV-B); even at ambient levels of UV-B radiation many organisms seem to be under UV stress. Because of their requirement for solar energy, the phytoplankton dwell in the top layers of the water column. In this near-surface position phytoplankton will be exposed to solar ultraviolet radiation. This radiation has been shown to affect growth, photosynthesis, nitrogen incorporation and enzyme activity. Other targets of solar UV irradiation are proteins and pigments involved in photosynthesis. Whether or not screening pigments can be induced in phytoplankton to effectively shield the organisms from excessive UV irradiation needs to be determined. Macroalgae show a distinct pattern of vertical distribution in their habitat. They have developed mechanisms to regulate their photosynthetic activity to adapt to the changing light regime and protect themselves from excessive radiation. A broad survey was carried out to understand photosynthesis in aquatic ecosystems and the different adaptation strategies to solar radiation of ecologically important species of green, red and brown algae from the North Sea, Baltic Sea, Mediterranean, Atlantic, polar and tropical oceans. Photoinhibition was quantified by oxygen exchange and by PAM (pulse amplitude modulated) fluorescence measurements based on transient changes of chlorophyll fluorescence. c2001 COSPAR Published by Elsevier Science Ltd. All rights reserved.

Generation of 369.4 nm Radiation by Efficient Doubling of a Diode Laser

NASA Technical Reports Server (NTRS)

Williams, A.; Seidel, D. J.; Maleki, J.

1993-01-01

A resonant cavity second harmonic generation system has been developed to produce 369.4 nm radiation from a 738.8 nm diode laser with 10 mW nominal output power. This system utilizes a polarization technique to lock the cavity to the laser frequency. In this paper we report on an evaluation of the system using a Titanium:Sapphire laser as the input source, and preliminary results with a diode laser source. To our knowledge, this is the deepest uv light ever produced by frequency-doubling a diode laser.

Interspecific Variability in Sensitivity to UV Radiation and Subsequent Recovery in Selected Isolates of Marine Bacteria†

PubMed Central

Arrieta, Jesús María; Weinbauer, Markus G.; Herndl, Gerhard J.

2000-01-01

The interspecific variability in the sensitivity of marine bacterial isolates to UV-B (295- to 320-nm) radiation and their ability to recover from previous UV-B stress were examined. Isolates originating from different microenvironments of the northern Adriatic Sea were transferred to aged seawater and exposed to artificial UV-B radiation for 4 h and subsequently to different radiation regimens excluding UV-B to determine the recovery from UV-B stress. Bacterial activity was assessed by thymidine and leucine incorporation measurements prior to and immediately after the exposure to UV-B and after the subsequent exposure to the different radiation regimens. Large interspecific differences among the 11 bacterial isolates were found in the sensitivity to UV-B, ranging from 21 to 92% inhibition of leucine incorporation compared to the bacterial activity measured in dark controls and from 14 to 84% for thymidine incorporation. Interspecific differences in the recovery from the UV stress were also large. An inverse relation was detectable between the ability to recover under dark conditions and the recovery under photosynthetic active radiation (400 to 700 nm). The observed large interspecific differences in the sensitivity to UV-B radiation and even more so in the subsequent recovery from UV-B stress are not related to the prevailing radiation conditions of the microhabitats from which the bacterial isolates originate. Based on our investigations on the 11 marine isolates, we conclude that there are large interspecific differences in the sensitivity to UV-B radiation and even larger differences in the mechanisms of recovery from previous UV stress. This might lead to UV-mediated shifts in the bacterioplankton community composition in marine surface waters. PMID:10742228

Solar ultraviolet-B radiation and vitamin D: a cross-sectional population-based study using data from the 2007 to 2009 Canadian Health Measures Survey.

PubMed

Greenfield, Jamie A; Park, Philip S; Farahani, Ellie; Malik, Suneil; Vieth, Reinhold; McFarlane, Norman A; Shepherd, Theodore G; Knight, Julia A

2012-08-15

Exposure to solar ultraviolet-B (UV-B) radiation is a major source of vitamin D3. Chemistry climate models project decreases in ground-level solar erythemal UV over the current century. It is unclear what impact this will have on vitamin D status at the population level. The purpose of this study was to measure the association between ground-level solar UV-B and serum concentrations of 25-hydroxyvitamin D (25(OH)D) using a secondary analysis of the 2007 to 2009 Canadian Health Measures Survey (CHMS). Blood samples collected from individuals aged 12 to 79 years sampled across Canada were analyzed for 25(OH)D (n = 4,398). Solar UV-B irradiance was calculated for the 15 CHMS collection sites using the Tropospheric Ultraviolet and Visible Radiation Model. Multivariable linear regression was used to evaluate the association between 25(OH)D and solar UV-B adjusted for other predictors and to explore effect modification. Cumulative solar UV-B irradiance averaged over 91 days (91-day UV-B) prior to blood draw correlated significantly with 25(OH)D. Independent of other predictors, a 1 kJ/m² increase in 91-day UV-B was associated with a significant 0.5 nmol/L (95% CI 0.3-0.8) increase in mean 25(OH)D (P = 0.0001). The relationship was stronger among younger individuals and those spending more time outdoors. Based on current projections of decreases in ground-level solar UV-B, we predict less than a 1 nmol/L decrease in mean 25(OH)D for the population. In Canada, cumulative exposure to ambient solar UV-B has a small but significant association with 25(OH)D concentrations. Public health messages to improve vitamin D status should target safe sun exposure with sunscreen use, and also enhanced dietary and supplemental intake and maintenance of a healthy body weight.

Features of the Photodegradation of 2,4-Dichlorophenoxyacetic Acid Under the Influence of Radiation from KrCl Excilamps

NASA Astrophysics Data System (ADS)

Vershinin, N. O.; Sokolova, I. V.; Tchaikovskaya, O. N.; Nevolina, K. A.

2015-11-01

The herbicide 2,4-dichlorophenoxyacetic acid was investigated in aqueous solution. A KrCl excilamp with an emission wavelength of 222 nm was used as radiation source. The direction of variation in the concentration of the toxicant during UV irradiation is discussed. The photodegradation constants are calculated. A chromatographic-mass spectrometric analysis of the photoproducts was undertaken.

Time-resolved experiments in the frequency domain using synchrotron radiation (invited)

NASA Astrophysics Data System (ADS)

De Stasio, Gelsomina; Giusti, A. M.; Parasassi, T.; Ravagnan, G.; Sapora, O.

1992-01-01

PLASTIQUE is the only synchrotron radiation beam line in the world that performs time-resolved fluorescence experiments in frequency domain. These experiments are extremely valuable sources of information on the structure and the dynamics of molecules. This technique measures fluorescence lifetimes with picosecond resolution in the near UV spectral range. Such accurate measurements are rendered possible by taking phase and modulation data, and by the advantages of the cross-correlation technique. A successful experiment demonstrated the radiation damage induced by low doses of radiation on rabbit blood cell membranes.

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

NASA Astrophysics Data System (ADS)

Feister, U.; Junk, J.; Woldt, M.

2008-01-01

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.

Characterising and testing deep UV LEDs for use in space applications

NASA Astrophysics Data System (ADS)

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

2015-12-01

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

Ultraviolet Radiations: Skin Defense-Damage Mechanism.

PubMed

Mohania, Dheeraj; Chandel, Shikha; Kumar, Parveen; Verma, Vivek; Digvijay, Kumar; Tripathi, Deepika; Choudhury, Khushboo; Mitten, Sandeep Kumar; Shah, Dilip

2017-01-01

UV-radiations are the invisible part of light spectra having a wavelength between visible rays and X-rays. Based on wavelength, UV rays are subdivided into UV-A (320-400 nm), UV-B (280-320 nm) and UV-C (200-280 nm). Ultraviolet rays can have both harmful and beneficial effects. UV-C has the property of ionization thus acting as a strong mutagen, which can cause immune-mediated disease and cancer in adverse cases. Numbers of genetic factors have been identified in human involved in inducing skin cancer from UV-radiations. Certain heredity diseases have been found susceptible to UV-induced skin cancer. UV radiations activate the cutaneous immune system, which led to an inflammatory response by different mechanisms. The first line of defense mechanism against UV radiation is melanin (an epidermal pigment), and UV absorbing pigment of skin, which dissipate UV radiation as heat. Cell surface death receptor (e.g. Fas) of keratinocytes responds to UV-induced injury and elicits apoptosis to avoid malignant transformation. In addition to the formation of photo-dimers in the genome, UV also can induce mutation by generating ROS and nucleotides are highly susceptible to these free radical injuries. Melanocortin 1 receptor (MC1R) has been known to be implicated in different UV-induced damages such as pigmentation, adaptive tanning, and skin cancer. UV-B induces the formation of pre-vitamin D3 in the epidermal layer of skin. UV-induced tans act as a photoprotection by providing a sun protection factor (SPF) of 3-4 and epidermal hyperplasia. There is a need to prevent the harmful effects and harness the useful effects of UV radiations.

Influences of the clearness index on UV solar radiation for two locations in the Tibetan Plateau-Lhasa and Haibei

NASA Astrophysics Data System (ADS)

Hu, Bo; Wang, Yuesi; Liu, Guangren

2008-09-01

Ultraviolet (UV) solar radiation has a significant influence on human health, the environment and climate. A series of measurements, including UV radiation (290-400 nm) and global solar radiation ( R s), were continuously recorded from August 2004 at the Lhasa and Haibei sites on the Tibetan Plateau. Both observation sites’ altitudes are above 3000 m and have similar meteorological conditions. The data from 2005-2006 was used to identify the varying characteristics of UV radiation. It’s relation to the clearness index K s, the relative optical mass m r, and R s were established. The annual mean values of total daily UV radiation are 0.92 and 0.67 MJ m-2 at Lhasa and Haibei, respectively. The UV radiation in Lhasa represented 4.6% of the global solar radiation while in Haibei this percentage was 4.2%. In the case of clear days ( K s > 0.8), these percentages ranged between 4.0% and 4.5% in Lhasa and between 5.1% and 5.5% in Haibei. In the case of cloudy days ( K s < 0.4), these percentages ranged from 4.4% to 6.8% in Lhasa and from 5.1% to 5.5% in Haibei. The maximum values of UV radiation for each relative optical mass diminished exponentially with m r. Thus, for Lhasa and Haibei, UV=46.25 m {4/-1.29}, and UV=51.76 m {r/-1.42}, respectively. The results of this study can be used to obtain more UV radiation data for the study of UV climate characteristics, the effects of UV on ecological processes and the feedback of the thinning of the stratospheric ozone, from more routine measurements R s data.

UV EFFECTS IN TOOTH ENAMEL AND THEIR POSSIBLE APPLICATION IN EPR DOSIMETRY WITH FRONT TEETH

PubMed Central

Sholom, S.; Desrosiers, M.; Chumak, V.; Luckyanov, N.; Simon, S.L.; Bouville, A.

2009-01-01

The effects of ultraviolet (UV) radiation on ionizing radiation biodosimetry were studied in human tooth enamel samples using the technique of electron paramagnetic resonance (EPR) in X-band. For samples in the form of grains, UV-specific EPR spectra were spectrally distinct from that produced by exposure to gamma radiation. From larger enamel samples, the UV penetration depth was determined to be in the 60–120 μm range. The difference in EPR spectra from UV exposure and from exposure to gamma radiation samples was found to be a useful marker of UV equivalent dose (defined as the apparent contribution to the gamma dose in mGy that results from UV radiation absorption) in tooth enamel. This concept was preliminarily tested on front teeth from inhabitants of the region of the Semipalatinsk Nuclear Test Site (Kazakhstan) who might have received some exposure to gamma radiation from the nuclear tests conducted there as well as from normal UV radiation in sunlight. The technique developed here to quantify and subtract the UV contribution to the measured tooth is currently limited to cumulative dose measurements with a component of UV equivalent dose equal to or greater than 300 mGy. PMID:20065706

Experiments on Dust Grain Charging

NASA Technical Reports Server (NTRS)

Abbas, M. N.; Craven, P. D.; Spann, J. F.; Tankosic, D.; LeClair, A.; West, E. A.

2004-01-01

Dust particles in various astrophysical environments are charged by a variety of mechanisms generally involving collisional processes with other charged particles and photoelectric emission with UV radiation from nearby sources. The sign and the magnitude of the particle charge are determined by the competition between the charging processes by UV radiation and collisions with charged particles. Knowledge of the particle charges and equilibrium potentials is important for understanding of a number of physical processes. The charge of a dust grain is thus a fundamental parameter that influences the physics of dusty plasmas, processes in the interplanetary medium and interstellar medium, interstellar dust clouds, planetary rings, cometary and outer atmospheres of planets etc. In this paper we present some results of experiments on charging of dust grains carried out on a laboratory facility capable levitating micron size dust grains in an electrodynamic balance in simulated space environments. The charging/discharging experiments were carried out by exposing the dust grains to energetic electron beams and UV radiation. Photoelectric efficiencies and yields of micron size dust grains of SiO2, and lunar simulates obtained from NASA-JSC will be presented.

Accumulation of flavonoids and related compounds in birch induced by UV-B irradiance.

PubMed

Lavola, Anu

1998-01-01

A growth chamber experiment was conducted to examine the effects of UV-B exposure (4.9 kJ m(-2) day(-1) of biologically effective UV-B, 280-320 nm) on shoot growth and secondary metabolite production in Betula pendula (Roth) and B. resinifera (Britt.) seedlings originating from environments in Finland, Germany and Alaska differing in solar UV-B radiation and climate. Neither shoot growth nor the composition of secondary metabolites was affected by UV-B irradiance, but the treatment induced significant changes in the amounts of individual secondary metabolites in leaves. Leaves of seedlings exposed to UV-B radiation contained higher concentrations of several flavonoids, condensed tannins and some hydroxycinnamic acids than leaves of control seedlings that received no UV-B radiation. At the population level, there was considerable variation in secondary metabolite responses to UV-B radiation: among populations, the induced response was most prominent in Alaskan populations, which were adapted to the lowest ambient UV-B radiation environment. I conclude that solar UV-B radiation plays an important role in the formation of secondary chemical characteristics in birch trees.

Area X-ray or UV camera system for high-intensity beams

DOEpatents

Chapman, Henry N.; Bajt, Sasa; Spiller, Eberhard A.; Hau-Riege, Stefan , Marchesini, Stefano

2010-03-02

A system in one embodiment includes a source for directing a beam of radiation at a sample; a multilayer mirror having a face oriented at an angle of less than 90 degrees from an axis of the beam from the source, the mirror reflecting at least a portion of the radiation after the beam encounters a sample; and a pixellated detector for detecting radiation reflected by the mirror. A method in a further embodiment includes directing a beam of radiation at a sample; reflecting at least some of the radiation diffracted by the sample; not reflecting at least a majority of the radiation that is not diffracted by the sample; and detecting at least some of the reflected radiation. A method in yet another embodiment includes directing a beam of radiation at a sample; reflecting at least some of the radiation diffracted by the sample using a multilayer mirror; and detecting at least some of the reflected radiation.

High-power, continuous-wave, solid-state, single-frequency, tunable source for the ultraviolet.

PubMed

Aadhi, A; Apurv Chaitanya, N; Singh, R P; Samanta, G K

2014-06-15

We report the development of a compact, high-power, continuous-wave, single-frequency, ultraviolet (UV) source with extended wavelength tunability. The device is based on single-pass, intracavity, second-harmonic-generation (SHG) of the signal radiation of a singly resonant optical parametric oscillator (SRO) working in the visible and near-IR wavelength range. The SRO is pumped in the green with a 25-mm-long, multigrating, MgO doped periodically poled stoichiometric lithium tantalate (MgO:sPPLT) as nonlinear crystal. Using three grating periods, 8.5, 9.0, and 9.5 μm of the MgO:sPPLT crystal and a single set of cavity mirrors, the SRO can be tuned continuously across 710.7-836.3 nm in the signal and corresponding idler across 2115.8-1462.1 nm with maximum idler power of 1.9 W and maximum out-coupled signal power of 254 mW. By frequency-doubling the intracavity signal with a 5-mm-long bismuth borate (BIBO) crystal, we can further tune the SRO continuously over 62.8 nm across 355.4-418.2 nm in the UV with maximum single-frequency UV power, as much as 770 mW at 398.28 nm in a Gaussian beam profile. The UV radiation has an instantaneous line-width of ∼14.5  MHz and peak-peak frequency stability of 151 MHz over 100 s. More than 95% of the tuning range provides UV power >260  mW. Access to lower UV wavelengths can in principle be realized by operating the SRO in the visible using shorter grating periods.

Lanthanum (III) regulates the nitrogen assimilation in soybean seedlings under ultraviolet-B radiation.

PubMed

Huang, Guangrong; Wang, Lihong; Zhou, Qing

2013-01-01

Ultraviolet-B (UV-B, 280-320 nm) radiation has seriously affected the growth of plants. Finding the technology/method to alleviate the damage of UV-B radiation has become a frontal topic in the field of environmental science. The pretreatment with rare earth elements (REEs) is an effective method, but the regulation mechanism of REEs is unknown. Here, the regulation effects of lanthanum (La(III)) on nitrogen assimilation in soybean seedlings (Glycine max L.) under ultraviolet-B radiation were investigated to elucidate the regulation mechanism of REEs on plants under UV-B radiation. UV-B radiation led to the inhibition in the activities of the key enzymes (nitrate reductase, glutamine synthetase, glutamate synthase) in the nitrogen assimilation, the decrease in the contents of nitrate and soluble proteins, as well as the increase in the content of amino acid in soybean seedlings. The change degree of UV-B radiation at the high level (0.45 W m(-2)) was higher than that of UV-B radiation at the low level (0.15 W m(-2)). The pretreatment with 20 mg L(-1) La(III) could alleviate the effects of UV-B radiation on the activities of nitrate reductase, glutamine synthetase, glutamate synthase, and glutamate dehydrogenase, promoting amino acid conversion and protein synthesis in soybean seedlings. The regulation effect of La(III) under UV-B radiation at the low level was better than that of UV-B radiation at the high level. The results indicated that the pretreatment with 20 mg L(-1) La(III) could alleviate the inhibition of UV-B radiation on nitrogen assimilation in soybean seedlings.

Use of radiation in biomaterials science

NASA Astrophysics Data System (ADS)

Benson, Roberto S.

2002-05-01

Radiation is widely used in the biomaterials science for surface modification, sterilization and to improve bulk properties. Radiation is also used to design of biochips, and in situ photopolymerizable of bioadhesives. The energy sources most commonly used in the irradiation of biomaterials are high-energy electrons, gamma radiation, ultraviolet (UV) and visible light. Surface modification involves placement of selective chemical moieties on the surface of a material by chemical reactions to improve biointeraction for cell adhesion and proliferation, hemocompatibility and water absorption. The exposure of a polymer to radiation, especially ionizing radiation, can lead to chain scission or crosslinking with changes in bulk and surface properties. Sterilization by irradiation is designed to inactivate most pathogens from the surface of biomedical devices. An overview of the use of gamma and UV radiation to improve surface tissue compatibility, bulk properties and surface properties for wear resistance, formation of hydrogels and curing dental sealants and bone adhesives is presented. Gamma and vacuum ultraviolet (VUV) irradiated ultrahigh molecular weight polyethylene (UHMWPE) exhibit improvement in surface modulus and hardness. The surface modulus and hardness of UHMWPE showed a dependence on type of radiation, dosage and processing. VUV surface modified e-PTFE vascular grafts exhibit increases in hydrophilicity and improvement towards adhesion of fibrin glue.

Impacts of varying light regimes on phycobiliproteins of Nostoc sp. HKAR-2 and Nostoc sp. HKAR-11 isolated from diverse habitats.

PubMed

Kannaujiya, Vinod K; Sinha, Rajeshwar P

2015-11-01

The adaptability of cyanobacteria in diverse habitats is an important factor to withstand harsh conditions. In the present investigation, the impacts of photosynthetically active radiation (PAR; 400-700 nm), ultraviolet-B (UV-B; 280-315 nm), and PAR + UV-B radiations on two cyanobacteria viz., Nostoc sp. HKAR-2 and Nostoc sp. HKAR-11 inhabiting diverse habitats such as hot springs and rice fields, respectively, were studied. Cell viability was about 14 % in Nostoc sp. HKAR-2 and <10 % in Nostoc sp. HKAR-11 after 48 h of UV-B exposure. PAR had negligible negative impact on the survival of both cyanobacteria. The continuous exposure of UV-B and PAR + UV-B showed rapid uncoupling, bleaching, fragmentation, and degradation in both phycocyanin (C-PC) and phycoerythrin (C-PE) subunits of phycobiliproteins (PBPs). Remarkable bleaching effect of C-PE and C-PC was not only observed with UV-B or PAR + UV-B radiation, but longer period (24-48 h) of exposure with PAR alone also showed noticeable negative impact. The C-PE and C-PC subunits of the rice field isolate Nostoc sp. HKAR-11 were severely damaged in comparison to the hot spring isolate Nostoc sp. HKAR-2 with rapid wavelength shifting toward shorter wavelengths denoting the bleaching of both the accessory light harvesting pigments. The results indicate that PBPs of the hot spring isolate Nostoc sp. HKAR-2 were more stable under various light regimes in comparison to the rice field isolate Nostoc sp. HKAR-11 that could serve as a good source of valuable pigments to be used in various biomedical and biotechnological applications.

Two ultraviolet radiation datasets that cover China

NASA Astrophysics Data System (ADS)

Liu, Hui; Hu, Bo; Wang, Yuesi; Liu, Guangren; Tang, Liqin; Ji, Dongsheng; Bai, Yongfei; Bao, Weikai; Chen, Xin; Chen, Yunming; Ding, Weixin; Han, Xiaozeng; He, Fei; Huang, Hui; Huang, Zhenying; Li, Xinrong; Li, Yan; Liu, Wenzhao; Lin, Luxiang; Ouyang, Zhu; Qin, Boqiang; Shen, Weijun; Shen, Yanjun; Su, Hongxin; Song, Changchun; Sun, Bo; Sun, Song; Wang, Anzhi; Wang, Genxu; Wang, Huimin; Wang, Silong; Wang, Youshao; Wei, Wenxue; Xie, Ping; Xie, Zongqiang; Yan, Xiaoyuan; Zeng, Fanjiang; Zhang, Fawei; Zhang, Yangjian; Zhang, Yiping; Zhao, Chengyi; Zhao, Wenzhi; Zhao, Xueyong; Zhou, Guoyi; Zhu, Bo

2017-07-01

Ultraviolet (UV) radiation has significant effects on ecosystems, environments, and human health, as well as atmospheric processes and climate change. Two ultraviolet radiation datasets are described in this paper. One contains hourly observations of UV radiation measured at 40 Chinese Ecosystem Research Network stations from 2005 to 2015. CUV3 broadband radiometers were used to observe the UV radiation, with an accuracy of 5%, which meets the World Meteorology Organization's measurement standards. The extremum method was used to control the quality of the measured datasets. The other dataset contains daily cumulative UV radiation estimates that were calculated using an all-sky estimation model combined with a hybrid model. The reconstructed daily UV radiation data span from 1961 to 2014. The mean absolute bias error and root-mean-square error are smaller than 30% at most stations, and most of the mean bias error values are negative, which indicates underestimation of the UV radiation intensity. These datasets can improve our basic knowledge of the spatial and temporal variations in UV radiation. Additionally, these datasets can be used in studies of potential ozone formation and atmospheric oxidation, as well as simulations of ecological processes.

The impact of solar UV radiation on the early biosphere

NASA Astrophysics Data System (ADS)

Horneck, G.

2007-08-01

Stratospheric ozone, photochemically produced from atmospheric oxygen, is a protective filter of the Earth's atmosphere by absorbing most of the biologically harmful UV radiation of our sun in the UV-C (190-280 nm) and short wavelength-region of the UV-B (280-315 nm). Numerous lines of isotopic and geologic evidence suggest that the Archean atmosphere was essentially anoxic. As a result the column abundance of ozone would have been insufficient to affect the surface UV radiation environment. Thus, as well as UV-B radiation, UV-C radiation would have penetrated to the Earth's surface with its associated biological consequences. The history of this ultraviolet stress for the early Earth has been determined from theoretical data and data obtained in Earth orbit on the inactivation of Bacillus subtilis spores under a simulated ozone layer of different thicknesses. Although the UV-C and UV-B regions contribute only 2 % of the entire solar extraterrestrial irradiance, photobiological experiments in space have demonstrated a high mutagenicity and lethality of this UV range to living organisms. The reason for these severe effects of extraterrestrial solar UV radiation - compared to conditions on present-day Earth - lies in the absorption characteristics of the DNA, which is the decisive target for inactivation and mutation induction at this UV range. Being a strong mutagen, UV-radiation is considered as a powerful promoter of biological evolution on the one hand, one the other hand, it may have deleterious consequences to individual cells and organisms, e.g. by causing inactivation, mutations or cancer induction. In response to potential harmful effects of environmental UV radiation, life on Earth has developed several strategies of survival, either avoiding exposure to UV radiation or restoring UV damage. Mechanisms of avoidance of exposure to UV radiation include (i) moving away from the UV radiation into shadowed areas, which requires the development of UV radiation sensing mechanisms; (ii) application of external shielding, such as covering by mud, sand or rock material; (iii) development of intrinsic UV screening pigments, such as tanning, inductive flavonoid production of plants, intracellular mycosporin production in cyanobacteria, (iv) accumulation of antioxidants and quenching substances. However, if UV damage has been induced - in spite of all avoidance efforts, organisms may restore their functionality by numerous repair processes. Repair pathways of a rich diversity and functional universality include (i) direct repair with the reversal of photochemical abnormalities, e.g. in the DNA; (ii) recombination repair removing the UV-induced abnormality by homologous recombination; and (iii) excision repair, where the section of the DNA strand containing the abnormality is removed and a repair patch is synthesized using the intact strand as a template. In addition to efficient repair systems for radiation-induced DNA injury, life has developed a variety of defense mechanisms, such as the increase in the production of stress proteins and the activation of the immune defence system. Some of these capacities have certainly already been evolved in the early biosphere, when it was exposed to the extended UV-spectrum of the sun. Only since the early Proterozoic, due to a rapid rise in the atmospheric oxygen concentration and consequently a photochemical built up of the stratospheric ozone layer, a more moderate UV radiation climate prevailed with wavelengths shorter than 295 nm being effectively cut off.

Ultraviolet-B and water stress effects on growth, gas exchange and oxidative stress in sunflower plants.

PubMed

Cechin, Inês; Corniani, Natália; de Fátima Fumis, Terezinha; Cataneo, Ana Catarina

2008-07-01

The effects and interaction of drought and UV-B radiation were studied in sunflower plants (Helianthus annuus L. var. Catissol-01), growing in a greenhouse under natural photoperiod conditions. The plants received approximately 1.7 W m(-2) (controls) or 8.6 W m(-2) (+UV-B) of UV-B radiation for 7 h per day. The UV-B and water stress treatments started 18 days after sowing. After a period of 12 days of stress, half of the water-stressed plants (including both UV-B irradiated or non-irradiated) were rehydrated. Both drought and UV-B radiation treatments resulted in lower shoot dry matter per plant, but there was no significant interaction between the two treatments. Water stress and UV-B radiation reduced photosynthesis, stomatal conductance and transpiration. However, the amplitude of the effects of both stressors was dependent on the interactions. This resulted in alleviation of the negative effect of drought on photosynthesis and transpiration by UV-B radiation as the water stress intensified. Intercelluar CO(2) concentration was initially reduced in all treatments compared to control plants but it increased with time. Photosynthetic pigments were not affected by UV-B radiation. Water stress reduced photosynthetic pigments only under high UV-B radiation. The decrease was more accentuated for chlorophyll a than for chlorophyll b. As a measure for the maximum efficiency of photosystem II in darkness F (v)/F (m) was used, which was not affected by drought stress but initially reduced by UV-B radiation. Independent of water supply, UV-B radiation increased the activity of pirogalol peroxidase and did not increase the level of malondialdehyde. On the other hand, water stress did not alter the activity of pirogalol peroxidase and caused membrane damage as assessed by lipid peroxidation. The application of UV-B radiation together with drought seemed to have a protective effect by lowering the intensity of lipid peroxidation caused by water stress. The content of proline was not affected by UV-B radiation but was increased by water stress under both low and high UV-B radiation. After 24 h of rehydration, most of the parameters analyzed recovered to the same level as the unstressed plants.

Spectral transmission of the pig lens: effect of ultraviolet A+B radiation.

PubMed

Artigas, C; Navea, A; López-Murcia, M-M; Felipe, A; Desco, C; Artigas, J-M

2014-12-01

To determine the spectral transmission curve of the crystalline lens of the pig. To analyse how this curve changes when the crystalline lens is irradiated with ultraviolet A+B radiation similar to that of the sun. To compare these results with literature data from the human crystalline lens. We used crystalline lenses of the common pig from a slaughterhouse, i.e. genetically similar pigs, fed with the same diet, and slaughtered at six months old. Spectral transmission was measured with a Perkin-Elmer Lambda 35 UV/VIS spectrometer. The lenses were irradiated using an Asahi Spectra Lax-C100 ultraviolet source, which made it possible to select the spectral emission band as well as the intensity and exposure time. The pig lens transmits all the visible spectrum (95%) and lets part of the ultraviolet A through (15%). Exposure to acute UV (A+B) irradiation causes a decrease in its transmission as the intensity or exposure time increases: this decrease is considerable in the UV region. We were able to determine the mean spectral transmission curve of the pig lens. It appears to be similar to that of the human lens in the visible spectrum, but different in the ultraviolet. Pig lens transmission is reduced by UV (A+B) irradiation and its transmission in the UV region can even disappear as the intensity or exposure time increases. An adequate exposure intensity and time of UV (A+B) radiation always causes an anterior subcapsular cataract (ASC). Copyright © 2014. Published by Elsevier Masson SAS.

Perspectives in melanoma prevention: the case of sunbeds.

PubMed

Autier, Philippe

2004-11-01

The incidence of cutaneous malignant melanoma (melanoma) and of basal cell carcinoma is still increasing in most fair-skinned populations. The fashion of intermittent exposure to solar ultraviolet (UV) radiations is considered the main cause of this increase. In 20 years time, tan acquisition through exposure to artificial sources of UV radiations has become frequent among fair-skinned adolescents and young adults. Modern sunbeds are powerful sources of UV radiations that do not exist in the nature, and repeated exposures to high doses of UVA constitute a new phenomenon in humans. A large prospective cohort study on 106,379 Norwegian and Swedish women conducted between 1991 and 1999 has provided evidence for a significant, moderate increase in melanoma risk among regular sunbed users. Failure of past case-control studies to document with consistency the sunbed-melanoma association was probably due to a too short latency period between sunbed use and melanoma diagnosis, and to too few subjects with high total durations of sunbed use. Regulations of sunbed installation, operation and use should become standardised across the 25 European Union countries. Enforcement of regulations in tanning parlours remains inadequate. In contrast, the existence of regulations is presented by many tanning salon operators as a guarantee that sunbed use is safe. We stress the need for the control of information disseminated by the "tanning industry" on suppositions that sunbed use is safer than sun exposure, and on the hypothetical health benefits of tanning. New fluorescent UV lamps are proposed that have a spectrum similar to the midday sun. Given the known association between intermittent sun exposure and melanoma, public-health authorities should reconsider the soundness of the commercialisation of these lamps.

Alteration of foliar flavonoid chemistry induced by enhanced UV-B radiation in field-grown Pinus ponderosa, Quercus rubra and Pseudotsuga menziesii.

PubMed

Warren, Jeffrey M; Bassman, John H; Mattinson, D Scott; Fellman, John K; Edwards, Gerald E; Robberecht, Ronald

2002-03-01

Chromatographic analyses of foliage from several tree species illustrate the species-specific effects of UV-B radiation on both quantity and composition of foliar flavonoids. Pinus ponderosa, Quercus rubra and Pseudotsuga menziesii were field-grown under modulated ambient (1x) and enhanced (2x) biologically effective UV-B radiation. Foliage was harvested seasonally over a 3-year period, extracted, purified and the flavonoid fraction applied to a mu Bondapak/C(18) column HPLC system sampling at 254 nm. Total flavonoid concentrations in Quercus rubra foliage were more than twice (leaf area basis) that of the other species; Pseudotsuga menziesii foliage had intermediate levels and P. ponderosa had the lowest concentrations of total flavonoids. No statistically significant UV-B radiation-induced effects were found in total foliar flavonoid concentrations for any species; however, concentrations of specific compounds within each species exhibited significant treatment effects. Higher (but statistically insignificant) levels of flavonoids were induced by UV-B irradiation in 1- and 2-year-old P. ponderosa foliage. Total flavonoid concentrations in 2-year-old needles increased by 50% (1x ambient UV-B radiation) or 70% (2x ambient UV-B radiation) from that of 1-year-old tissue. Foliar flavonoids of Q. rubra under enhanced UV-B radiation tended to shift from early-eluting compounds to less polar flavonoids eluting later. There were no clear patterns of UV-B radiation effects on 1-year-old P. menziesii foliage. However, 2-year-old tissue had slightly higher foliar flavonoids under the 2x UV-B radiation treatment compared to ambient levels. Results suggest that enhanced UV-B radiation will alter foliar flavonoid composition and concentrations in forest tree species, which could impact tissue protection, and ultimately, competition, herbivory or litter decomposition.

Dielectric Barrier Discharge based Mercury-free plasma UV-lamp for efficient water disinfection.

PubMed

Prakash, Ram; Hossain, Afaque M; Pal, U N; Kumar, N; Khairnar, K; Mohan, M Krishna

2017-12-12

A structurally simple dielectric barrier discharge based mercury-free plasma UV-light source has been developed for efficient water disinfection. The source comprises of a dielectric barrier discharge arrangement between two co-axial quartz tubes with an optimized gas gap. The outer electrode is an aluminium baked foil tape arranged in a helical form with optimized pitch, while the inner electrode is a hollow aluminium metallic rod, hermetically sealed. Strong bands peaking at wavelengths 172 nm and 253 nm, along with a weak band peaking at wavelength 265 nm have been simultaneously observed due to plasma radiation from the admixture of xenon and iodine gases. The developed UV source has been used for bacterial deactivation studies using an experimental setup that is an equivalent of the conventional house-hold water purifier system. Deactivation studies for five types of bacteria, i.e., E. coli, Shigella boydii, Vibrio, Coliforms and Fecal coliform have been demonstrated with 4 log reductions in less than ten seconds.

The VIMOS Ultra Deep Survey: Nature, ISM properties, and ionizing spectra of CIII]λ1909 emitters at z = 2-4

NASA Astrophysics Data System (ADS)

Nakajima, K.; Schaerer, D.; Le Fèvre, O.; Amorín, R.; Talia, M.; Lemaux, B. C.; Tasca, L. A. M.; Vanzella, E.; Zamorani, G.; Bardelli, S.; Grazian, A.; Guaita, L.; Hathi, N. P.; Pentericci, L.; Zucca, E.

2018-05-01

Context. Ultraviolet (UV) emission-line spectra are used to spectroscopically confirm high-z galaxies and increasingly also to determine their physical properties. Aims: We construct photoionization models to interpret the observed UV spectra of distant galaxies in terms of the dominant radiation field and the physical condition of the interstellar medium (ISM). These models are applied to new spectroscopic observations from the VIMOS Ultra Deep Survey (VUDS). Methods: We construct a large grid of photoionization models, which use several incident radiation fields (stellar populations, active galactic nuclei (AGNs), mix of stars and AGNs, blackbodies, and others), and cover a wide range of metallicities and ionization parameters. From these models we derive new spectral UV line diagnostics using equivalent widths (EWs) of [CIII]λ1909 doublet, CIVλ1549 doublet and the line ratios of [CIII], CIV, and He IIλ1640 recombination lines. We apply these diagnostics to a sample of 450 [CIII]-emitting galaxies at redshifts z = 2-4 previously identified in VUDS. Results: We demonstrate that our photoionization models successfully reproduce observations of nearby and high-redshift sources with known radiation field and/or metallicity. For star-forming galaxies our models predict that [CIII] EW peaks at sub-solar metallicities, whereas CIV EW peaks at even lower metallicity. Using the UV diagnostics, we show that the average star-forming galaxy (EW([CIII]) 2 Å) based on the composite of the 450 UV-selected galaxies' spectra The inferred metallicity and ionization parameter is typically Z = 0.3-0.5 Z⊙ and logU = -2.7 to - 3, in agreement with earlier works at similar redshifts. The models also indicate an average age of 50-200 Myr since the beginning of the current star-formation, and an ionizing photon production rate, ξion, of logξion/erg-1 Hz = 25.3-25.4. Among the sources with EW([CIII]) >= 10 Å, approximately 30% are likely dominated by AGNs. The metallicity derived for galaxies with EW(CIII) = 10-20 Å is low, Z = 0.02-0.2 Z⊙, and the ionization parameter higher (logU -1.7) than the average star-forming galaxy. To explain the average UV observations of the strongest but rarest [CIII] emitters (EW([CIII]) > 20 Å), we find that stellar photoionization is clearly insufficient. A radiation field consisting of a mix of a young stellar population (logξion/erg-1 Hz 25.7) plus an AGN component is required. Furthermore an enhanced C/O abundance ratio (up to the solar value) is needed for metallicities Z = 0.1-0.2 Z⊙ and logU = -1.7 to - 1.5. Conclusions: A large grid of photoionization models has allowed us to propose new diagnostic diagrams to classify the nature of the ionizing radiation field (star formation or AGN) of distant galaxies using UV emission lines, and to constrain their ISM properties. We have applied this grid to a sample of [CIII]-emitting galaxies at z = 2-4 detected in VUDS, finding a range of physical properties and clear evidence for significant AGN contribution in rare sources with very strong [CIII] emission. The UV diagnostics we propose should also serve as an important basis for the interpretation of upcoming observations of high-redshift galaxies. Based on data obtained with the European Southern Observatory Very Large Telescope, Paranal, Chile, under Large Program 185.A-0791.JSPS Overseas Research Fellow.

Influence of UV radiation on chlorophyll, and antioxidant enzymes of wetland plants in different types of constructed wetland.

PubMed

Xu, Defu; Wu, Yinjuan; Li, Yingxue; Howard, Alan; Jiang, Xiaodong; Guan, Yidong; Gao, Yongxia

2014-09-01

A surface- and vertical subsurface-flow-constructed wetland were designed to study the response of chlorophyll and antioxidant enzymes to elevated UV radiation in three types of wetland plants (Canna indica, Phragmites austrail, and Typha augustifolia). Results showed that (1) chlorophyll content of C. indica, P. austrail, and T. augustifolia in the constructed wetland was significantly lower where UV radiation was increased by 10 and 20 % above ambient solar level than in treatment with ambient solar UV radiation (p < 0.05). (2) The malondialdehyde (MDA) content, guaiacol peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) activities of wetland plants increased with elevated UV radiation intensity. (3) The increased rate of MDA, SOD, POD, and CAT activities of C. indica, P. australis, and T. angustifolia by elevated UV radiation of 10 % was higher in vertical subsurface-flow-constructed wetland than in surface-flow-constructed wetland. The sensitivity of MDA, SOD, POD, and CAT activities of C. indica, P. austrail, and T. augustifolia to the elevated UV radiation was lower in surface-flow-constructed wetland than in the vertical subsurface-flow-constructed wetland, which was related to a reduction in UV radiation intensity through the dissolved organic carbon and suspended matter in the water. C. indica had the highest SOD and POD activities, which implied it is more sensitive to enhanced UV radiation. Therefore, different wetland plants had different antioxidant enzymes by elevated UV radiation, which were more sensitive in vertical subsurface-flow-constructed wetland than in surface-flow-constructed wetland.

UV-C induces K sup + efflux from bean but not from oat leaves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huerta, A.J.; Gueltig, B.G.

Previous reports have shown that ultraviolet radiation (UV) induces a specific leakage of K{sup +} from cells in culture as well as from guard cells of bean leaves resulting in stomatal closure. In an effort to determine how general this response may be in photosynthetic leaf cells, we measured the UV-C-induced K{sup +} efflux from irradiated 10-14 day-old bean and oat leaf sections. Our results show that oat leaves do not respond to UV-C irradiation with K{sup +} efflux. However UV-C irradiated bean leaves leaked K{sup +} at a rate of approximately 47 nmoles cm{sup {minus}2} h{sup {minus}1} and themore » leakage was linear for at least 3.5 hours. The source cells for K{sup +} efflux and the possible mechanisms responsible for this difference in UV-sensitivity will be discussed.« less

Protective effect of rare earth against oxidative stress under ultraviolet-B radiation.

PubMed

Wang, Lihong; Huang, Xiaohua; Zhou, Qing

2009-04-01

The effects of lanthanum (III) (La(III)) in protecting soybean leaves against oxidative stress induced by ultraviolet-B (UV-B) radiation were investigated. The increase in contents of hydrogen peroxide (H(2)O(2)) and superoxide (O2*-) due to UV-B radiation suggested oxidative stress. The increase in the content of malondialdehyde (MDA) and the decrease in the index of unsaturated fatty acid (IUFA) indicated oxidative damage on cell membrane induced by UV-B radiation. La(III) partially reversed UV-B-radiation-induced damage of plant growth. The reduction in the contents of H(2)O(2), O2*-, and MDA and increase in the content of IUFA, compared with UV-B treatment, also indicated that La(III) alleviated the oxidative damage induced by UV-B radiation. The increase in the activities of superoxide dismutase and peroxidase and the contents of ascorbate, carotenoids, and flavonoids were observed in soybean leaves with La(III) + UV-B treatment, compared with UV-B treatment. Our data suggested that La(III) could protect soybean plants from UV-B-radiation-induced oxidative stress by reacting with reactive oxygen species directly or by improving the defense system of plants.

Side- and end-illumination of polymer optical fibers in the UV region

NASA Astrophysics Data System (ADS)

Eckhardt, Hanns-S.; Jungling, B.; Klein, Karl-Friedrich; Poisel, Hans

2003-07-01

Since more than 2 decades, the polymer optical fiber (POF) based on PMMA is well known. A lot of applications were studied and initiated: in addition to data transmission, the automotive, lighting and sensor applications are of main interest. Due to the spectral attenuation and applications, light-sources like broadband metal-halide lamps and halogen lamps, or LEDs and laser-diodes are mainly used. Due to improvement in manufacturing of the standard step-index POF, the variations of the spectral attenuation in the blue region have been reduced. Therefore, the losses are acceptable for short-length applications in the UV-A region. Using different light-sources like high-power Xenon-lamp, deuterium-lamp or UV-LEDs, the UV-damage is an important factor. In addition to the basic attenuation, the UV-induced losses will be determined by experiment, in the interesting UV-A region. The higher flexibilty of the thick-core POF is superior in comparison to silica or glass fibers with the same outer diameter. Therefore, the bending losses in the UV-region are important, too. For special applications in the medical field, side-illuminating fibers are highly accepted. The axial and spectral dependence on the lateral radiation pattern will be described, using a very thick fiber.

Ultraviolet-B phototoxicity and hypothetical photomelanomagenesis: intraocular and crystalline lens photoprotection.

PubMed

Mainster, Martin A; Turner, Patricia L

2010-04-01

Ultraviolet-B (UV-B) radiation can cause phototoxic macular injuries in young people who have been sunbathing but not sungazing and in welders. Welders have a reportedly increased risk of uveal melanoma. We analyze phakic and pseudophakic risks for solar and welding arc UV-B exposure. Optical radiation measurement, analysis, and perspective. Spectral transmittances were measured for UV-transmitting, UV-blocking, and blue-blocking intraocular lenses (IOLs). The photoprotective performances of crystalline and intraocular lenses were analyzed using relevant epidemiologic and laboratory data and action spectra for acute retinal phototoxicity and melanoma photocarcinogenesis. Crystalline lens UV-B retinal protection is deficient in children and young adults, increasing their potential susceptibility to acute retinal phototoxicity and hypothetical photomelanomagenesis. UV-B radiation has sufficient energy/photon to induce primary melanomagenic DNA lesions, unlike blue light or UV-A radiation. UV-blocking and blue-blocking IOLs have negligible UV-B transmittance. UV-transmitting IOL transmittance of UV-B radiation is equivalent to that of a 15-year-old crystalline lens. If optical radiation exposure is responsible for welders' increased risk of uveal melanoma, then UV-B radiation is the most probable causative agent and spectacle wear is a potential confounding factor in epidemiologic studies of ocular melanoma. Welders under 30 years of age are at greater risk for welding maculopathy than older welders. Children, adults under 30 years of age, and pseudophakic individuals with UV-transmitting IOLs should wear sunglasses in bright environments because of the UV-B window in their crystalline lenses or IOLs. Copyright 2010 Elsevier Inc. All rights reserved.

Effects of UV-B radiation on the isoflavone accumulation and physiological-biochemical changes of soybean during germination: Physiological-biochemical change of germinated soybean induced by UV-B.

PubMed

Ma, Meng; Wang, Pei; Yang, Runqiang; Gu, Zhenxin

2018-06-01

In this study, the effects of UV-B radiation on the isoflavones accumulation, physiological and nutritional quality, water status, and characteristics of proteins in germinated soybeans were investigated. The results showed that isoflavones content in soybeans increased with appropriate intensity and time of UV-B radiation and decreased with excessive treatment. Fresh weight, length, free amino acids, reducing sugar contents and bulk water (T 23 ) in germinated soybeans decreased with increasing radiation time, indicating that UV-B inhibited the growth and nutrients metabolism of soybean during germination. Cell damage was detected in germinated soybeans with excessive UV-B radiation, as shown by the black spots in cotyledons and the increased intercellular water determined by LF-NMR. Germination resulted in an increase in random coil structures, while UV-B radiation induced no obvious changes in FT-IR spectrum and protein conformation of soybeans. Both UV-B radiation and germination caused the increase in soluble proteins, especially in 1.0-75.0 kDa fraction. Copyright © 2018 Elsevier Ltd. All rights reserved.

The changes in quality ingredients of Qi chrysanthemum flowers treated with elevated UV-B radiation at different growth stages.

PubMed

Yao, Xiaoqin; Chu, Jianzhou; He, Xueli; Ma, Chunhui; Han, Chao; Shen, Haiyu

2015-05-01

The paper mainly reported the changes in quality ingredients of Qi chrysanthemum flowers treated with elevated UV-B radiation at different growth stages. The experiment included two levels of UV-B radiation (ambient UV-B, a 10% increase in ambient UV-B). Elevated UV-B radiation was carried out for 10-days during seedling, vigorous growth, bud and flower stages of Qi chrysanthemum, respectively. Elevated UV-B treatments applied during four development stages did not significantly affect flower yield, the rate of superoxide radical production and malondialdehyde concentration in flowers, while increased free amino acid concentration. The amino acid concentration induced by elevated UV-B radiation applied during bud stage was higher than that during the other stages. Elevated UV-B radiation applied during vigorous growth (except for flavone), bud and flower stages of chrysanthemum significantly increased hydrogen peroxide concentration, phenylalanine ammonia lyase enzyme activity, vitamin C, chlorogenic acid and flavone concentrations in flowers. These results suggested that active and nutritional ingredients in flowers of chrysanthemum could be increased by elevated UV-B radiation applied during the later growth stages of chrysanthemum. The paper supplied a simple and environmental-friendly method to improve quality of medicinal plants. Copyright © 2015 Elsevier B.V. All rights reserved.

Measurements of DNA Damage and Repair in Bacillus anthracis Sterne Spores by UV Radiation

DTIC Science & Technology

2014-09-18

MEASUREMENTS OF DNA DAMAGE AND REPAIR IN BACILLUS ANTHRACIS STERNE SPORES BY UV RADIATION...AFIT-ENP-T-14-S-01 MEASUREMENTS OF DNA DAMAGE AND REPAIR IN BACILLUS ANTHRACIS STERNE SPORES BY UV RADIATION THESIS Presented to the... DAMAGE AND REPAIR IN BACILLUS ANTHRACIS STERNE SPORES BY UV RADIATION Chelsea C. Marcum, BS Approved

Effects of different levels of vitamin C on UV radiation-induced DNA damage

NASA Astrophysics Data System (ADS)

Zhou, Dianfeng; Heng, Hang; Ji, Kang; Ke, Weizhong

2005-05-01

The Raman spectra of DNA in different levels of vitamin C with 10- and 30-min ultraviolet (UV) radiations were reported. The intensity of UV radiation was 18.68 W/m2. The experimental results proved that vitamin C could alone prevent UV radiation from damaging DNA, but the effects depended on the concentration of vitamin C. When the concentration of vitamin C was about 0.08-0.4 mmol/L, vitamin C decreased UV radiation-induced DNA's damage. When the concentration of vitamin C exceeded 0.4 mmol/L, vitamin C accelerated DNA's damage instead. Maybe the reason is that when DNA in aqueous solution is radiated by UV, free radicals come into being, and vitamin C can scavenge free radicals, so vitamin C in lower concentration can protect DNA. The quantity of free radicals is finite, when vitamin C is superfluous, free radicals have been scavenged absolutely and vitamin C is residual. Vitamin C is a strong reductant. When the mixture of DNA and residual vitamin C is radiated by UV, vitamin C reacts with DNA. The more residual vitamin C and the longer time of UV radiation, the more DNA is damaged.

Long-term exposure to enhanced UV-B radiation has no significant effects on growth or secondary compounds of outdoor-grown Scots pine and Norway spruce seedlings.

PubMed

Turtola, Satu; Sallas, Leena; Holopainen, Jarmo K; Julkunen-Tiitto, Riitta; Kainulainen, Pirjo

2006-11-01

The effects of long-term enhanced UV-B radiation on growth and secondary compounds of two conifer species were studied in an outdoor experiment. Scots pine (Pinus sylvestris) seedlings were exposed for two growing seasons and Norway spruce (Picea abies) seedlings for three growing seasons to supplemental UV-B radiation, corresponding to a 30% increase in ambient UV-B radiation. The experiment also included appropriate controls for ambient and increased UV-A radiation. Enhanced UV-B did not affect the growth of the conifer seedlings. In addition, neither the concentrations of terpenes and phenolics in the needles nor the concentrations of terpenes in the wood were affected. However, in the UV-A control treatment the concentrations of diterpenes in the wood of Scots pine decreased significantly compared to the ambient control. Apparently, a small increase in UV-B radiation has no significant effects on the secondary compounds and growth of Scots pine and Norway spruce seedlings.

The effect of ultraviolet radiation on the pathogenesis of Candida albicans in mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Denkins, Y.M.

1991-01-01

This dissertation addresses questions concerning the effects of UV radiation on the pathogenesis of opportunistic fungal pathogens such as Candida albicans. UV radiation decreased the survival of Candida-infected mice; however, no correlation was found between suppression of the delayed type hypersensitivity (DTH) response and the course of lethal infection. This suggested that DTH was not protective against lethal disease with this organism. UV radiation also changed the persistence of the organism in the internal organs. UV-irradiated, infected animals had increased numbers of Candida in their kidneys compared to non-irradiated mice. Sensitization prior to UV irradiation aided clearance of the organismmore » from the kidneys of UV-irradiated mice. These data show that UV radiation suppresses cell-mediated immunity to Candida albicans in mice and increases mortality of Candida-infected mice. Moreover, the data suggest that an increase in environmental UV radiation could increase the severity of pathogenic infections.« less

Combined effects of Lanthanum(III) and elevated Ultraviolet-B radiation on root nitrogen nutrient in soybean seedlings.

PubMed

Huang, Guangrong; Wang, Lihong; Sun, Zhaoguo; Li, Xiaodong; Zhou, Qing; Huang, Xiaohua

2015-02-01

Rare earth element pollution and elevated ultraviolet-B (UV-B) radiation occur simultaneously in some regions, but the combined effects of these two factors on plants have not attracted enough attention. Nitrogen nutrient is vital to plant growth. In this study, the combined effects of lanthanum(III) and elevated UV-B radiation on nitrate reduction and ammonia assimilation in soybean (Glycine max L.) roots were investigated. Treatment with 0.08 mmol L(-1) La(III) did not change the effects of elevated UV-B radiation on nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS), glutamate synthase (GOGAT), glutamate dehydrogenase (GDH), nitrate, ammonium, amino acids, or soluble protein in the roots. Treatment with 0.24 mmol L(-1) La(III) and elevated UV-B radiation synergistically decreased the NR, NiR, GS, and GOGAT activities as well as the nitrate, amino acid, and soluble protein levels, except for the GDH activity and ammonium content. Combined treatment with 1.20 mmol L(-1) La(III) and elevated UV-B radiation produced severely deleterious effects on all test indices, and these effects were stronger than those induced by La(III) or elevated UV-B radiation treatment alone. Following the withdrawal of La(III) and elevated UV-B radiation, all test indices for the combined treatments with 0.08/0.24 mmol L(-1) La(III) and elevated UV-B radiation recovered to a certain extent, but they could not recover for treatments with 1.20 mmol L(-1) La(III) and elevated UV-B radiation. In summary, combined treatment with La(III) and elevated UV-B radiation seriously affected nitrogen nutrition in soybean roots through the inhibition of nitrate reduction and ammonia assimilation.

Optical and X-ray luminosities of expanding nebulae around ultraluminous X-ray sources

NASA Astrophysics Data System (ADS)

Siwek, Magdalena; Sądowski, Aleksander; Narayan, Ramesh; Roberts, Timothy P.; Soria, Roberto

2017-09-01

We have performed a set of simulations of expanding, spherically symmetric nebulae inflated by winds from accreting black holes in ultraluminous X-ray sources (ULXs). We implemented a realistic cooling function to account for free-free and bound-free cooling. For all model parameters we considered, the forward shock in the interstellar medium becomes radiative at a radius ˜100 pc. The emission is primarily in optical and UV, and the radiative luminosity is about 50 per cent of the total kinetic luminosity of the wind. In contrast, the reverse shock in the wind is adiabatic so long as the terminal outflow velocity of the wind vw ≳ 0.003c. The shocked wind in these models radiates in X-rays, but with a luminosity of only ˜1035 erg s-1. For wind velocities vw ≲ 0.001c, the shocked wind becomes radiative, but it is no longer hot enough to produce X-rays. Instead it emits in optical and UV, and the radiative luminosity is comparable to 100 per cent of the wind kinetic luminosity. We suggest that measuring the optical luminosities and putting limits on the X-ray and radio emission from shock-ionized ULX bubbles may help in estimating the mass outflow rate of the central accretion disc and the velocity of the outflow.

Tunable, continuous-wave, ultraviolet source based on intracavity sum-frequency-generation in an optical parametric oscillator using BiB₃O₆.

PubMed

Devi, Kavita; Kumar, S Chaitanya; Ebrahim-Zadeh, M

2013-10-21

We report a continuous-wave (cw) source of tunable radiation across 333-345 nm in the ultraviolet (UV) using bismuth triborate, BiB₃O₆ (BIBO) as the nonlinear gain material. The source is based on internal sum-frequency-generation (SFG) in a cw singly-resonant optical parametric oscillator (OPO) pumped at 532 nm. The compact tunable source employs a 30-mm-long MgO:sPPLT crystal as the OPO gain medium and a 5-mm-long BIBO crystal for intracavity SFG of the signal and pump, providing up to 21.6 mW of UV power at 339.7 nm, with >15 mW over 64% of the SFG tuning range. The cw OPO is also tunable across 1158-1312 nm in the idler, delivering as much as 1.7 W at 1247 nm, with >1W over 65% of the tuning range. The UV output at maximum power exhibits passive power stability better than 3.4% rms and frequency stability of 193 GHz over more than one minute.

Raman spectroscopic analysis of the responds of desert cyanobacterium Nostoc sp under UV-B radiation

NASA Astrophysics Data System (ADS)

Wang, Gaohong; Hao, Zongjie; Hu, Chunxiang; Liu, Yongding

Cyanobacteria are renowned for tolerating extremes of desiccation, UV radiation, freezethaw cycles, hypersalinity and oligotrophy, which make them as candidate par excellence for terraforming in extraterrestrial planet. Recently Raman spectrum was applied to study the biochemical information changes in different field of life science. In this study, we investigated the respond of desert cyanobactreium Nostoc sp under UV-B radiation via FT-Raman spectra. It was found that the spectral biomarkers of protectant molecular of UV radiation such as β-carotene and scytonemin were induced by UV-B radiation, but Chlorophyll a content was decreased, and also the photosynthesis activity was inhibited significantly. After light adaptation without UV-B radiation, the Chlorophyll a content and photosynthesis activity returned to high level, butβ-carotene and scytonemin content remained in the cells. Those results indicated that desert Cyanobacteria have good adaptation ability for UV-B radiation and synthesis of protectant molecular may be an effective strategy for its adaptation in evolution.

Tea extracts protect normal lymphocytes but not leukemia cells from UV radiation-induced ROS production: An EPR spin trap study.

PubMed

Tepe Çam, Semra; Polat, Mustafa; Esmekaya, Meriç Arda; Canseven, Ayşe G; Seyhan, Nesrin

2015-08-01

An ex vivo method for detection of free radicals and their neutralization by aqueous tea in human normal lymphocytes and MEC-1 leukemia cells under ultraviolet (UV) irradiation was investigated. This method is based on the electron paramagnetic resonance (EPR) spectroscopy spin-trapping technique. 5-tert-butoxycarbonyl 5-methyl-1-pyrroline N-oxide (BMPO) was used as the spin trap. Normal human lymphocytes and leukemia cells were exposed to UVB radiation (290-315 nm) at 47.7 and 159 mJ/cm(2) and to UVA radiation (315-400 nm) at 53.7 J/cm(2). No significant radical production at 47.7 mJ/cm(2) UVB dose in both cell lines was observed. In normal cells, free radical production was observed at 159 mJ/cm(2) UVB and 53.7 J/cm(2) UVA doses. However, both UV sources did not significantly produce free radicals in leukemia cells. A radical scavenging property of tea extracts (black, green, sage, rosehip) was observed in normal lymphocytes after both UVB and UVA exposure. In leukemia cells, the intensities of EPR signals produced in BMPO with tea extracts were found to be increased substantially after UVA exposure. These results showed that UV radiation induced free radical formation in normal human lymphocytes and indicated that tea extracts may be useful as photoprotective agents for them. On the other hand, tea extracts facilitated free radical production in leukemia cells.

Effects of UV-B radiation on growth, photosynthesis, UV-B-absorbing compounds and NADP-malic enzyme in bean (Phaseolus vulgaris L.) grown under different nitrogen conditions.

PubMed

Pinto, M E; Casati, P; Hsu, T P; Ku, M S; Edwards, G E

1999-02-01

The effects of UV-B radiation on growth, photosynthesis, UV-B-absorbing compounds and NADP-malic enzyme have been examined in different cultivars of Phaseolous vulgaris L. grown under 1 and 12 mM nitrogen. Low nitrogen nutrition reduces chlorophyll and soluble protein contents in the leaves and thus the photosynthesis rate and dry-matter accumulation. Chlorophyll, soluble protein and Rubisco contents and photosynthesis rate are not significantly altered by ambient levels of UV-B radiation (17 microW m-2, 290-320 nm, 4 h/day for one week). Comparative studies show that under high nitrogen, UV-B radiation slightly enhances leaf expansion and dry-matter accumulation in cultivar Pinto, but inhibits these parameters in Vilmorin. These results suggest that the UV-B effect on growth is mediated through leaf expansion, which is particularly sensitive to UV-B, and that Pinto is more tolerant than Vilmorin. The effect of UV-B radiation on UV-B-absorbing compounds and on NADP-malic enzyme (NADP-ME) activity is also examined. Both UV-B radiation and low-nitrogen nutrition enhance the content of UV-B-absorbing compounds, and among the three cultivars used, Pinto exhibits the highest increases and Arroz the lowest. The same trend is observed for the specific activity and content of NADP-ME. On a leaf-area basis, the amount of UV-B-absorbing compounds is highly correlated with the enzyme activity (r2 = 0.83), suggesting that NADP-ME plays a key role in biosynthesis of these compounds. Furthermore, the higher sensitivity of Vilmorin than Pinto to UV-B radiation appears to be related to the activity of NADP-ME and the capacity of the plants to accumulate UV-B-absorbing compounds.

Comparison of UV Protection Properties of Cotton Fabrics Treated with Aqueous and Methanolic Extracts of Achyranthes aspera and Alhagi maurorum Plants.

PubMed

Nazir, Ahsan; Saleem, Muhammad Asad; Nazir, Faiza; Hussain, Tanveer; Faizan, Muhammad Qasim; Usman, Muhammad

2016-03-01

UV radiations are high-energy radiations present in sunlight that can damage human skin. Protection against these radiations becomes vital especially in those areas of the globe where UV index is quite high that makes the inhabitants more prone to dangerous effects of UV radiations. Clothing materials are good blockers of UV radiations, particularly when the fabric cover factor is high and/or the fabrics contain suitable UV-blocking finishes. In this study, effect of application of aqueous and methanolic extracts of two different plants, i.e., Achyranthes aspera and Alhagi maurorum on UV protection properties of cotton fabric was investigated. The results showed that the fabric samples treated with extracts of both the plants have excellent UV protection properties as indicated by their ultraviolet protection factor. It was concluded that both the aqueous and methanolic plant extracts are very effective in blocking UVA and UVB radiations, when applied on cotton fabrics. The UV protection performance of Achyranthes aspera extracts was much better as compared to that of Alhagi maurorum, and methanolic extracts of both the plants outperformed the aqueous extracts in terms of UV protection. © 2016 The American Society of Photobiology.

Soybean resistance to stink bugs (Nezara viridula and Piezodorus guildinii) increases with exposure to solar UV-B radiation and correlates with isoflavonoid content in pods under field conditions.

PubMed

Zavala, Jorge A; Mazza, Carlos A; Dillon, Francisco M; Chludil, Hugo D; Ballaré, Carlos L

2015-05-01

Solar UV-B radiation (280-315 nm) has a significant influence on trophic relationships in natural and managed ecosystems, affecting plant-insect interactions. We explored the effects of ambient UV-B radiation on the levels of herbivory by stink bugs (Nezara viridula and Piezodorus guildinii) in field-grown soybean crops. The experiments included two levels of UV-B radiation (ambient and attenuated UV-B) and four soybean cultivars known to differ in their content of soluble leaf phenolics. Ambient UV-B radiation increased the accumulation of the isoflavonoids daidzin and genistin in the pods of all cultivars. Soybean crops grown under attenuated UV-B had higher numbers of unfilled pods and damaged seeds than crops grown under ambient UV-B radiation. Binary choice experiments with soybean branches demonstrated that stink bugs preferred branches of the attenuated UV-B treatment. We found a positive correlation between percentage of undamaged seeds and the contents of daidzin and genistin in pods. Our results suggest that constitutive and UV-B-induced isoflavonoids increase plant resistance to stink bugs under field conditions. © 2014 John Wiley & Sons Ltd.

Laboratory Investigations of the Complex Refractory Organic Material Produced from Irradiation of Pluto Ice Analogs

NASA Technical Reports Server (NTRS)

Materese, Christopher K.; Cruikshank, Dale P.; Sanford, Scott A.; Imanaka, Hiroshi

2014-01-01

Much of Pluto's surface consists of N2 ice with smaller amounts of CH4 and CO ices. Despite the low temperature (approximately 45K), chemistry can be driven in the surface ices by radiation processing such as cosmic ray bombardment. When cosmic rays strike the surface, much of their energy is dispersed in the form of secondary electrons, which in turn drive much of the resulting chemical reactions. Laboratory experiments designed to simulate the conditions on these icy bodies may provide insight into this chemistry. Significant progress has been made in the laboratory toward understanding the smaller, simple compounds produced in the solid phase by radiation processing of (N2, CH4, CO) ices (Bohn et al. 1994; Moore & Hudson 2003; Hodyss et al. 2011; Kim and Kaiser 2012). Recently Materese et al. (2014) used a variety of techniques to better characterize the refractory materials produced from the UV photo-irradiation of N2:CH4:CO ices. However, because Pluto's atmosphere is optically thick to Lyman-alpha UV radiation it is important to re-examine the results using an alternate radiation source. Our latest work has consisted of the analysis of refractory materials produced from the electron bombardment of low temperature N2(-), CH4(-), and CO(-)containing ices (100:1:1). The ice mixture was chosen to be analogous to the known surface ices on Pluto and the radiation source was chosen to mimic the secondary electrons produced by cosmic rays bombardment. The residues were studied using multiple chemical techniques including, infrared (IR) spectroscopy, X-ray absorption near-edge structure (XANES) spectroscopy, and gas chromatography coupled with mass spectrometry (GC-MS). The organic residues produced in these experiments can be seen as an analog for the refractory component of the surface of Pluto, and are compared with the residues previously obtained from UV photo-irradiation. UV and near- IR spectroscopy of the surfaces of Pluto and Charon during the encounter with NASA's New Horizons spacecraft in 2015, will give the first close-up measurements of ices and their photoproducts. Laboratory measurements and experiments will provide a better context for the data returned by the spacecraft.

Nicotinamide Enhances Repair of Arsenic and Ultraviolet Radiation-Induced DNA Damage in HaCaT Keratinocytes and Ex Vivo Human Skin

PubMed Central

Thompson, Benjamin C.; Halliday, Gary M.; Damian, Diona L.

2015-01-01

Arsenic-induced skin cancer is a significant global health burden. In areas with arsenic contamination of water sources, such as China, Pakistan, Myanmar, Cambodia and especially Bangladesh and West Bengal, large populations are at risk of arsenic-induced skin cancer. Arsenic acts as a co-carcinogen with ultraviolet (UV) radiation and affects DNA damage and repair. Nicotinamide (vitamin B3) reduces premalignant keratoses in sun-damaged skin, likely by prevention of UV-induced cellular energy depletion and enhancement of DNA repair. We investigated whether nicotinamide modifies DNA repair following exposure to UV radiation and sodium arsenite. HaCaT keratinocytes and ex vivo human skin were exposed to 2μM sodium arsenite and low dose (2J/cm2) solar-simulated UV, with and without nicotinamide supplementation. DNA photolesions in the form of 8-oxo-7,8-dihydro-2′-deoxyguanosine and cyclobutane pyrimidine dimers were detected by immunofluorescence. Arsenic exposure significantly increased levels of 8-oxo-7,8-dihydro-2′-deoxyguanosine in irradiated cells. Nicotinamide reduced both types of photolesions in HaCaT keratinocytes and in ex vivo human skin, likely by enhancing DNA repair. These results demonstrate a reduction of two different photolesions over time in two different models in UV and arsenic exposed cells. Nicotinamide is a nontoxic, inexpensive agent with potential for chemoprevention of arsenic induced skin cancer. PMID:25658450

Photobiology of vitamin D in mushrooms and its bioavailability in humans

PubMed Central

Keegan, Raphael-John H.; Lu, Zhiren; Bogusz, Jaimee M.; Williams, Jennifer E.; Holick, Michael F.

2013-01-01

Mushrooms exposed to sunlight or UV radiation are an excellent source of dietary vitamin D2 because they contain high concentrations of the vitamin D precursor, provitamin D2. When mushrooms are exposed to UV radiation, provitamin D2 is converted to previtamin D2. Once formed, previtamin D2 rapidly isomerizes to vitamin D2 in a similar manner that previtamin D3 isomerizes to vitamin D3 in human skin. Continued exposure of mushrooms to UV radiation results in the production of lumisterol2 and tachysterol2. It was observed that the concentration of lumisterol2 remained constant in white button mushrooms for up to 24 h after being produced. However, in the same mushroom tachysterol2 concentrations rapidly declined and were undetectable after 24 h. Shiitake mushrooms not only produce vitamin D2 but also produce vitamin D3 and vitamin D4. A study of the bioavailability of vitamin D2 in mushrooms compared with the bioavailability of vitamin D2 or vitamin D3 in a supplement revealed that ingestion of 2000 IUs of vitamin D2 in mushrooms is as effective as ingesting 2000 IUs of vitamin D2 or vitamin D3 in a supplement in raising and maintaining blood levels of 25-hydroxyvitamin D which is a marker for a person's vitamin D status. Therefore, mushrooms are a rich source of vitamin D2 that when consumed can increase and maintain blood levels of 25-hydroxyvitamin D in a healthy range. Ingestion of mushrooms may also provide the consumer with a source of vitamin D3 and vitamin D4. PMID:24494050

Occupational UVR skin protection by make-up.

PubMed

Bonner, R; Khazova, M; O'Hagan, J B; Squire, H

2012-03-01

New legislation has been introduced in the Member States of the European Union, covering worker exposure to artificial optical radiation. Use of make-up could reduce the ultraviolet hazard level and provide additional protection for skin against UV radiation (UVR). This is particularly important in entertainment and filming where intentional exposure of the actors and presenters to the very intense light sources may be required for extended periods of time. This document presents the assessment of UVR protection of make-up used in entertainment and demonstrates that the protection level varies considerably for different luminaires and application techniques. An important practical implication of this finding is that make-up alone cannot be considered as a reliable protection measure against skin exposure to actinic UV.

Phosphor blends for high-CRI fluorescent lamps

DOEpatents

Setlur, Anant Achyut [Niskayuna, NY; Srivastava, Alok Mani [Niskayuna, NY; Comanzo, Holly Ann [Niskayuna, NY; Manivannan, Venkatesan [Clifton Park, NY; Beers, William Winder [Chesterland, OH; Toth, Katalin [Pomaz, HU; Balazs, Laszlo D [Budapest, HU

2008-06-24

A phosphor blend comprises at least two phosphors each selected from one of the groups of phosphors that absorb UV electromagnetic radiation and emit in a region of visible light. The phosphor blend can be applied to a discharge gas radiation source to produce light sources having high color rendering index. A phosphor blend is advantageously includes the phosphor (Tb,Y,LuLa,Gd).sub.x(Al,Ga).sub.yO.sub.12:Ce.sup.3+, wherein x is in the range from about 2.8 to and including 3 and y is in the range from about 4 to and including 5.

The Optical/UV Excess of X-Ray-dim Isolated Neutron Stars. I. Bremsstrahlung Emission from a Strangeon Star Atmosphere

NASA Astrophysics Data System (ADS)

Wang, Weiyang; Lu, Jiguang; Tong, Hao; Ge, Mingyu; Li, Zhaosheng; Men, Yunpeng; Xu, Renxin

2017-03-01

X-ray-dim isolated neutron stars (XDINSs) are characterized by Planckian spectra in X-ray bands, but show optical/ultraviolet (UV) excesses: the factors by which the measured photometry exceeds those extrapolated from X-ray spectra. To solve this problem, a radiative model of bremsstrahlung emission from a plasma atmosphere is established in the regime of a strangeon star. A strangeon star atmosphere could simply be regarded as the upper layer of a normal neutron star. This plasma atmosphere, formed and maintained by the interstellar-medium-accreted matter due to the so-called strangeness barrier, is supposed to be of two temperatures. All seven XDINS spectra could be well fitted by the radiative model, from optical/UV to X-ray bands. The fitted radiation radii of XDINSs are from 7 to 13 km, while the modeled electron temperatures are between 50 and 250 eV, except RX J0806.4-4123, with a radiation radius of ˜3.5 km, indicating that this source could be a low-mass strangeon star candidate. This strangeon star model could further be tested by soft X-ray polarimetry, such as the Lightweight Asymmetry and Magnetism Probe, which is expected to be operational on China’s space station around 2020.

The Optical/UV Excess of X-Ray-dim Isolated Neutron Stars. I. Bremsstrahlung Emission from a Strangeon Star Atmosphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Weiyang; Lu, Jiguang; Men, Yunpeng

X-ray-dim isolated neutron stars (XDINSs) are characterized by Planckian spectra in X-ray bands, but show optical/ultraviolet (UV) excesses: the factors by which the measured photometry exceeds those extrapolated from X-ray spectra. To solve this problem, a radiative model of bremsstrahlung emission from a plasma atmosphere is established in the regime of a strangeon star. A strangeon star atmosphere could simply be regarded as the upper layer of a normal neutron star. This plasma atmosphere, formed and maintained by the interstellar-medium-accreted matter due to the so-called strangeness barrier, is supposed to be of two temperatures. All seven XDINS spectra could bemore » well fitted by the radiative model, from optical/UV to X-ray bands. The fitted radiation radii of XDINSs are from 7 to 13 km, while the modeled electron temperatures are between 50 and 250 eV, except RX J0806.4–4123, with a radiation radius of ∼3.5 km, indicating that this source could be a low-mass strangeon star candidate. This strangeon star model could further be tested by soft X-ray polarimetry, such as the Lightweight Asymmetry and Magnetism Probe, which is expected to be operational on China’s space station around 2020.« less

Bacterial Survival under Extreme UV Radiation: A Comparative Proteomics Study of Rhodobacter sp., Isolated from High Altitude Wetlands in Chile

PubMed Central

Pérez, Vilma; Hengst, Martha; Kurte, Lenka; Dorador, Cristina; Jeffrey, Wade H.; Wattiez, Ruddy; Molina, Veronica; Matallana-Surget, Sabine

2017-01-01

Salar de Huasco, defined as a polyextreme environment, is a high altitude saline wetland in the Chilean Altiplano (3800 m.a.s.l.), permanently exposed to the highest solar radiation doses registered in the world. We present here the first comparative proteomics study of a photoheterotrophic bacterium, Rhodobacter sp., isolated from this remote and hostile habitat. We developed an innovative experimental approach using different sources of radiation (in situ sunlight and UVB lamps), cut-off filters (Mylar, Lee filters) and a high-throughput, label-free quantitative proteomics method to comprehensively analyze the effect of seven spectral bands on protein regulation. A hierarchical cluster analysis of 40 common proteins revealed that all conditions containing the most damaging UVB radiation induced similar pattern of protein regulation compared with UVA and visible light spectral bands. Moreover, it appeared that the cellular adaptation of Rhodobacter sp. to osmotic stress encountered in the hypersaline environment from which it was originally isolated, might further a higher resistance to damaging UV radiation. Indeed, proteins involved in the synthesis and transport of key osmoprotectants, such as glycine betaine and inositol, were found in very high abundance under UV radiation compared to the dark control, suggesting the function of osmolytes as efficient reactive oxygen scavengers. Our study also revealed a RecA-independent response and a tightly regulated network of protein quality control involving proteases and chaperones to selectively degrade misfolded and/or damaged proteins. PMID:28694800

Photo-recovery of electron-irradiated GaAs solar cells

NASA Technical Reports Server (NTRS)

Meulenberg, Andrew

1995-01-01

The first long-term (3000 hours) UV testing of unirradiated and 1 MeV electron-irradiated GaAs solar cells, with multilayer-coated coverslides to reduce solar array operating temperature, has produced some unexpected and important results. Two results, independent of the coverslide coatings, are of particular importance in terms of the predictability of GaAs solar-array lifetime in space: ( 1) The GaAs/Ge solar cells used for this series of tests displayed a much higher radiation degradation than that predicted based on JPL Solar Cell Radiation Handbook data. Covered cells degraded more in Isc than did bare cells. Short-term illumination at 60 C did not produce significant recovery (-1%) of the radiation damage. (2) However, electron radiation damage to these GaAs solar celIs anneals at 40 C when exposed to approximately 1 sun AM0 UV light sources for extended periods. The effect appears to be roughly linear with time (-1% of lsc per 1000 UVSH), is large (greater than or equal to 3%), and has not yet saturated (at 3000 hours). This photo-recovery of radiation damage to GaAs solar cells is a new effect and potentially important to the spacecraft community. The figure compares the effects of extended UV on irradiated and unirradiated GaAs solar cells with INTELSAT-6 Si cells. The effect and its generality, the extent of and conditions for photo-recovery, and the implications of such recovery for missions in radiation environments have not yet been determined.

The enhancement of biological ocular UV radiation on beaches compared to the radiation on grass.

PubMed

Liu, Guang-Cong; Wang, Fang; Gao, Yan-Yan; Yang, Zheng; Hu, Li-Wen; Gao, Qian; Ri, Jun-Chol; Liu, Yang

2014-12-01

The influence of albedo on ocular UV exposure has seldom been reported. This paper aimed to explore the enhancement effect on measured ocular UV radiation due to a sand surface compared to measured ocular UV radiation due to a grass surface. We measured ambient and ocular UV radiation over the beach and grass surface in Sanya City of China (18.4°N, 109.7°E). The experimental apparatus was composed of a manikin and a dual-detector spectrometer. Integration of both UVA and UVB radiation was used to denote UV radiation. Then biologically effective ocular UVB radiation (UVBE) and the ratios of UVBE of two surfaces were calculated. Maximum of ocular UV radiation versus time over the two surfaces is bimodal. UVBE on the beach is significantly larger than UVBE on the sand, and UVBE peaked at different solar elevation angle (SEA) over the two surfaces (about 53° and 40° on the beach and grass, respectively, according to Bayesian regression). The maximum of ocular UVBE ratios is greater than two, which peaked SEA was about 50°. One hour's cumulative radiation under sunny weather exceeds thresholds for photokeratitis, conjunctivitis and lens damage. Higher albedo significantly increased biological ocular UV radiation. Tourists on tropical beaches should take protective measures and avoid facing the sun directly, especially when SEA is around 50°. Copyright © 2014 Elsevier B.V. All rights reserved.

Calibration of space instruments at the Metrology Light Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klein, R., E-mail: roman.klein@ptb.de; Fliegauf, R.; Gottwald, A.

2016-07-27

PTB has more than 20 years of experience in the calibration of space-based instruments using synchrotron radiation to cover the UV, VUV and X-ray spectral range. New instrumentation at the electron storage ring Metrology Light Source (MLS) opens up extended calibration possibilities within this framework. In particular, the set-up of a large vacuum vessel that can accommodate entire space instruments opens up new prospects. Moreover, a new facility for the calibration of radiation transfer source standards with a considerably extended spectral range has been put into operation. Besides, characterization and calibration of single components like e.g. mirrors, filters, gratings, andmore » detectors is continued.« less

The ultraviolet radiation environment in the habitable zones around low-mass exoplanet host stars

NASA Astrophysics Data System (ADS)

France, Kevin; Linsky, Jeffrey L.; Loyd, R. O. Parke

2014-11-01

The EUV (200-911 Å), FUV (912-1750 Å), and NUV (1750-3200 Å) spectral energy distribution of exoplanet host stars has a profound influence on the atmospheres of Earth-like planets in the habitable zone. The stellar EUV radiation drives atmospheric heating, while the FUV (in particular, Ly α) and NUV radiation fields regulate the atmospheric chemistry: the dissociation of H2O and CO2, the production of O2 and O3, and may determine the ultimate habitability of these worlds. Despite the importance of this information for atmospheric modeling of exoplanetary systems, the EUV/FUV/NUV radiation fields of cool (K and M dwarf) exoplanet host stars are almost completely unconstrained by observation or theory. We present observational results from a Hubble Space Telescope survey of M dwarf exoplanet host stars, highlighting the importance of realistic UV radiation fields for the formation of potential biomarker molecules, O2 and O3. We conclude by describing preliminary results on the characterization of the UV time variability of these sources.

Deep UV emitting scintillators for alpha and beta particle detection

NASA Astrophysics Data System (ADS)

Zhou, Y.; Jia, D. D.; Lewis, L. A.; Feofilov, S. P.; Meltzer, R. S.

2011-03-01

Several deep UV emitting scintillators, whose emission falls in the solar blind region of the spectrum (200-280 nm), are described and their scintillator properties are characterized. They include LaPO 4:Pr, YPO 4:Pr, YAlO 3:Pr, Pr(PO 3) 3, YPO 4:Bi and ScPO 4. These materials would facilitate the detection of ionizing radiation in open areas, even during the daylight hours, and could be used to support large area surveys that monitor for the presence of ionization radiation due, for example, to system leaks or transfer contamination. These materials can be used in the form of powders, thin films or paints for radiation detection. They are characterized for both beta radiation using electron beams (2-35 keV) and 137Cs and alpha radiations using 241Am sources. Their absolute light yields are estimated and are compared to that of Y 2SiO 5:Ce. Their light yields decrease as a function of electron energy but at 10 keV they approach 8000 ph/MeV.

Critical analysis of active methods of ozone layer recovery

NASA Astrophysics Data System (ADS)

Bekker, S. Z.; Doronin, A. P.; Kozlov, S. I.

2017-09-01

A critical analysis is given for various methods for recovery of the ozone layer of the Earth: the emission of alkane gases, the destruction of freons by laser IR radiation and with microwave discharge, exposure to laser UV radiation and electric discharge in the atmosphere, the use of solar radiation, laser infrared radiation, and gamma rays, and the creation of an artificial formation at high altitudes that shields the solar radiation dissociating ozone. The optimal methods are discussed in terms of their effectiveness, economic costs, and environmental consequences. These include the use of gamma rays sources, electric discharge in the atmosphere, and microwave breakdown.

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

PubMed

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

2015-05-01

Plants synthesize phenolic compounds in response to certain environmental signals or stresses. One large group of phenolics, flavonoids, is considered particularly responsive to ultraviolet (UV) radiation. However, here we demonstrate that solar blue light stimulates flavonoid biosynthesis in the absence of UV-A and UV-B radiation. We grew pea plants (Pisum sativum cv. Meteor) outdoors, in Finland during the summer, under five types of filters differing in their spectral transmittance. These filters were used to (1) attenuate UV-B; (2) attenuate UV-B and UV-A < 370 nm; (3) attenuate UV-B and UV-A; (4) attenuate UV-B, UV-A and blue light; and (5) as a control not attenuating these wavebands. Attenuation of blue light significantly reduced the flavonoid content in leaf adaxial epidermis and reduced the whole-leaf concentrations of quercetin derivatives relative to kaempferol derivatives. In contrast, UV-B responses were not significant. These results show that pea plants regulate epidermal UV-A absorbance and accumulation of individual flavonoids by perceiving complex radiation signals that extend into the visible region of the solar spectrum. Furthermore, solar blue light instead of solar UV-B radiation can be the main regulator of phenolic compound accumulation in plants that germinate and develop outdoors. © 2014 John Wiley & Sons Ltd.

Response of antioxidant defense system to laser radiation apical meristem of Isatis indigotica seedlings exposed to UV-B.

PubMed

Chen, Yi-Ping

2009-07-01

To determine the response of antioxidant defense system to laser radiation apical meristem of Isatis indigotica seedlings, Isatis indigotica seedlings were subjected to UV-B radiation (10.08 kJ m(-2)) for 8 h day(-1) for 8 days (PAR, 220 micromol m(-2) s(-1)) and then exposed to He-Ne laser radiation (633 nm; 5.23 mW mm(-2); beam diameter: 1.5 mm) for 5 min each day without ambient light radiation. Changes in free radical elimination systems were measured, the results indicate that: (1) UV-B radiation enhanced the concentration of Malondialdahyde (MDA) and decreased the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) in seedlings compared with the control. The concentration of MDA was decreased and the activities of SOD, CAT and POD were increased when seedlings were subjected to elevated UV-B damage followed by laser; (2) the concentration of UV absorbing compounds and proline were increased progressively with UV-B irradiation, laser irradiation and He-Ne laser irradiation plus UV-B irradiation compared with the control. These results suggest that laser radiation has an active function in repairing UV-B-induced lesions in seedlings.

Cell damage caused by ultraviolet B radiation in the desert cyanobacterium Phormidium tenue and its recovery process.

PubMed

Wang, Gaohong; Deng, Songqiang; Liu, Jiafeng; Ye, Chaoran; Zhou, Xiangjun; Chen, Lanzhou

2017-10-01

Phormidium tenue, a cyanobacterium that grows in the topsoil of biological soil crusts (BSCs), has the highest recovery rate among desert crust cyanobacteria after exposure to ultraviolet B (UV-B) radiation. However, the mechanism underlying its recovery process is unclear. To address this issue, we measured chlorophyll a fluorescence, generation of reactive oxygen species (ROS), lipid peroxidation, and repair of DNA breakage in P. tenue following exposure to UV-B. We found that UV-B radiation at all doses tested reduced photosynthesis and induced cell damage in P. tenue. However, P. tenue responded to UV-B radiation by rapidly reducing photosynthetic activity, which protects the cell by leaking less ROS. Antioxidant enzymes, DNA damage repair systems, and UV absorbing pigments were then induced to mitigate the damage caused by UV-B radiation. The addition of exogenous antioxidant chemicals ascorbate and N-acetylcysteine also mitigated the harmful effects caused by UV-B radiation and enhanced the recovery process. These chemicals could aid in the resistance of P. tenue to the exposure of intense UV-B radiation in desertified areas when inoculated onto the sand surface to form artificial algal crusts. Copyright © 2017. Published by Elsevier Inc.

Detection of ultraviolet radiation using tissue equivalent radiochromic gel materials

NASA Astrophysics Data System (ADS)

Bero, M. A.; Abukassem, I.

2009-05-01

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.

Long-term variations of the UV-B radiation over Central Europe since early 1960s, as revealed from the UV observations and reconstructed data

NASA Astrophysics Data System (ADS)

Krzyscin, J. W.

2003-04-01

A method of reconstruction of the UV variations for periods when UV-B measurements were not carried out is proposed. The reconstruction is based on observations of total (Sun+sky) radiation by a pyranometer, Dobson total ozone, sunshine duriation from the Campbel Stokes heliograph, and atmospheric column water content taken from NCEP/NOAA reanalysis. Modeled all-sky erythemaly weighted daily dose is calculated as a product of the cloud reduction factor (CRF) over UV range and clear-sky dose from a radiative transfer model. CRF over UV range is estimated from measured CRF for total solar radiation and the statistical dependence relating CRF over UV with that over whole solar spectrum. The measured daily UV doses and daily sum of total radiation taken at Belsk, Poland (52N, 21E) for the period 1976-2001 have been used to construct the regressions for various solar zenith angles. The time series of monthly means from the modeled daily UV doses follows the observed monthly means supporting the possibility of reconstruction of the UV time series for other periods. An inspection of the long-term stability of total radiation measurements is necessary to discuss trends in the reconstructed time series. We examine the data homogeneity analyzing the ratio of the observed to modeled total radiation for fully clear sky days that are selected from the daily values of sunshine duration measured by the Campbel-Stokes heliograph. Combining reconstructed and observed monthly means of the UV doses we found a positive trend in the UV radiation in the period 1980-1995 and almost constant UV level for other periods (early 60s up to 1980, and 1995-2001). The trend pattern suggests dominating role of the long-term total ozone forcing on the UV level with a small impact of the long-term changes in the cloud/aerosol properties.

Chromosphere Active Region Plasma Diagnostics Based On Observations Of Millimeter Radiation

NASA Astrophysics Data System (ADS)

Loukitcheva, M.; Nagnibeda, V.

1999-10-01

In this paper we present the results of millimeter radiation calculations for different elements of chromospheric and transition region structures of the quiet Sun and S-component - elements of chromosphere network, sunspot groups and plages. The calculations were done on the basis of standard optical and UV models ( models by Vernazza et al. (1981,VAL), their modifications by Fontenla et al. (1993,FAL)). We also considered the sunspot model by Lites and Skumanich (1982,LS), S-component model by Staude et al.(1984) and modification of VAL and FAL models by Bocchialini and Vial - models NET and CELL. We compare these model calculations with observed characteristics of components of millimeter Solar radiation for the quiet Sun and S-component obtained with the radiotelescope RT-7.5 MGTU (wavelength 3.4 mm) and radioheliograph Nobeyama (wavelength 17.6 mm). From observations we derived spectral characteristics of millimeter sources and active region source structure. The comparison has shown that observed radio data are clearly in dissagrement with all the considered models. Finally, we propose further improvement of chromospheric and transition region models based on optical and UV observations in order to use for modelling information obtained from radio data.

UV-Induced cell death in plants.

PubMed

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

2013-01-14

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

UV-Induced Cell Death in Plants

PubMed Central

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

2013-01-01

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

The B3-VLA CSS sample. VIII. New optical identifications from the Sloan Digital Sky Survey The ultraviolet-optical spectral energy distribution of the young radio sources

NASA Astrophysics Data System (ADS)

Fanti, C.; Fanti, R.; Zanichelli, A.; Dallacasa, D.; Stanghellini, C.

2011-04-01

Context. Compact steep-spectrum radio sources and giga-hertz peaked spectrum radio sources (CSS/GPS) are generally considered to be mostly young radio sources. In recent years we studied at many wavelengths a sample of these objects selected from the B3-VLA catalog: the B3-VLA CSS sample. Only ≈60% of the sources were optically identified. Aims: We aim to increase the number of optical identifications and study the properties of the host galaxies of young radio sources. Methods: We cross-correlated the CSS B3-VLA sample with the Sloan Digital Sky Survey (SDSS), DR7, and complemented the SDSS photometry with available GALEX (DR 4/5 and 6) and near-IR data from UKIRT and 2MASS. Results: We obtained new identifications and photometric redshifts for eight faint galaxies and for one quasar and two quasar candidates. Overall we have 27 galaxies with SDSS photometry in five bands, for which we derived the ultraviolet-optical spectral energy distribution (UV-O-SED). We extended our investigation to additional CSS/GPS selected from the literature. Most of the galaxies show an excess of ultra-violet (UV) radiation compared with the UV-O-SED of local radio-quiet ellipticals. We found a strong dependence of the UV excess on redshift and analyzed it assuming that it is generated either from the nucleus (hidden quasar) or from a young stellar population (YSP). We also compare the UV-O-SEDs of our CSS/GPS sources with those of a selection of large size (LSO) powerful radio sources from the literature. Conclusions: If the major process of the UV excess is caused by a YSP, our conclusion is that it is the result of the merger process that also triggered the onset of the radio source with some time delay. We do not see evidence for a major contribution from a YSP triggered by the radio sources itself. Appendices A-G are only available in electronic form at http://www.aanda.org

The interaction between abiotic photodegradation and microbial decomposition under ultraviolet radiation.

PubMed

Wang, Jing; Liu, Lingli; Wang, Xin; Chen, Yiwei

2015-05-01

Elevated ultraviolet (UV) radiation has been demonstrated to stimulate litter decomposition. Despite years of research, it is still not fully understood whether the acceleration in litter degradation is primarily attributed to abiotic photodegradation or the combined effects of abiotic photodegradation and microbial decomposition. In this study, we used meta-analysis to synthesize photodegradation studies and compared the effects of UV radiation on litter decomposition between abiotic and biotic conditions. We also conducted a microcosm experiment to assess the effects of UV radiation on litter biodegradability and microbial activity. Overall, our meta-analysis found that under abiotic photodegradation, UV radiation reduced the remaining litter mass by 1.44% (95% CI: 0.85% to 2.08%), did not affect the remaining lignin and increased the dissolved organic carbon (DOC) concentration by 14.01% (1.49-23.67%). Under combined abiotic photodegradation and microbial decomposition, UV radiation reduced the remaining litter mass and lignin by 1.60% (0.04-3.58%) and 16.07% (9.27-24.23%), respectively, but did not alter DOC concentration. UV radiation had no significant impact on soil microbial biomass carbon (MBC), but it reduced microbial respiration by 44.91% (2.26-78.62%) and altered the composition of the microbial community. In addition, UV radiation reduced nitrogen (N) immobilization by 19.44% (4.77-37.92%). Our microcosm experiment further indicated that DOC concentration and the amount of respired C in UV-treated litter increased with UV exposure time, suggesting that longer UV exposure resulted in greater biodegradability. Overall, our study suggested that UV exposure could increase litter biodegradability by increasing the microbial accessibility of lignin, as well as the labile carbon supply to microbes. However, the remaining litter mass was not different between the abiotic and biotic conditions, most likely because the positive effect of UV radiation on litter biodegradability was offset by its negative effect on microbial activity. Our results also suggested that UV radiation could alter the N cycle during decomposition, primarily by inhibiting N immobilization. © 2014 John Wiley & Sons Ltd.

Synchrotron Radiation Workshop (SRW)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chubar, O.; Elleaume, P.

2013-03-01

"Synchrotron Radiation Workshop" (SRW) is a physical optics computer code for calculation of detailed characteristics of Synchrotron Radiation (SR) generated by relativistic electrons in magnetic fields of arbitrary configuration and for simulation of the radiation wavefront propagation through optical systems of beamlines. Frequency-domain near-field methods are used for the SR calculation, and the Fourier-optics based approach is generally used for the wavefront propagation simulation. The code enables both fully- and partially-coherent radiation propagation simulations in steady-state and in frequency-/time-dependent regimes. With these features, the code has already proven its utility for a large number of applications in infrared, UV, softmore » and hard X-ray spectral range, in such important areas as analysis of spectral performances of new synchrotron radiation sources, optimization of user beamlines, development of new optical elements, source and beamline diagnostics, and even complete simulation of SR based experiments. Besides the SR applications, the code can be efficiently used for various simulations involving conventional lasers and other sources. SRW versions interfaced to Python and to IGOR Pro (WaveMetrics), as well as cross-platform library with C API, are available.« less

Ultraviolet radiation and the snow alga Chlamydomonas nivalis (Bauer) Wille.

PubMed

Gorton, Holly L; Vogelmann, Thomas C

2003-06-01

Aplanospores of Chlamydomonas nivalis are frequently found in high-altitude, persistent snowfields where they are photosynthetically active despite cold temperatures and high levels of visible and ultraviolet (UV) radiation. The goals of this work were to characterize the UV environment of the cells in the snow and to investigate the existence and localization of screening compounds that might prevent UV damage. UV irradiance decreased precipitously in snow, with UV radiation of wavelengths 280-315 nm and UV radiation of wavelengths 315-400 nm dropping to 50% of incident levels in the top 1 and 2 cm, respectively. Isolated cell walls exhibited UV absorbance, possibly by sporopollenin, but this absorbance was weak in images of broken or plasmolyzed cells observed through a UV microscope. The cells also contained UV-absorbing cytoplasmic compounds, with the extrachloroplastic carotenoid astaxanthin providing most of the screening. Additional screening compound(s) soluble in aqueous methanol with an absorption maximum at 335 nm played a minor role. Thus, cells are protected against potentially high levels of UV radiation by the snow itself when they live several centimeters beneath the surface, and they rely on cellular screening compounds, chiefly astaxanthin, when located near the surface where UV fluxes are high.

Long-term solar UV radiation reconstructed by ANN modelling with emphasis on spatial characteristics of input data

NASA Astrophysics Data System (ADS)

Feister, U.; Junk, J.; Woldt, M.; Bais, A.; Helbig, A.; Janouch, M.; Josefsson, W.; Kazantzidis, A.; Lindfors, A.; den Outer, P. N.; Slaper, H.

2008-06-01

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. Special emphasis will be given to the discussion of small-scale characteristics of input data to the ANN model. 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.

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

NASA Technical Reports Server (NTRS)

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

1987-01-01

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

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

NASA Astrophysics Data System (ADS)

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

1998-11-01

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

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

PubMed

Latimer, J G; Mitchell, C A; Mitchell, G A

1987-06-01

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

UV-B radiation-induced oxidative stress and p38 signaling pathway involvement in the benthic copepod Tigriopus japonicus.

PubMed

Kim, Bo-Mi; Rhee, Jae-Sung; Lee, Kyun-Woo; Kim, Min-Jung; Shin, Kyung-Hoon; Lee, Su-Jae; Lee, Young-Mi; Lee, Jae-Seong

2015-01-01

Ultraviolet B (UV-B) radiation presents an environmental hazard to aquatic organisms. To understand the molecular responses of the intertidal copepod Tigriopus japonicus to UV-B radiation, we measured the acute toxicity response to 96 h of UV-B radiation, and we also assessed the intracellular reactive oxygen species (ROS) levels, glutathione (GSH) content, and antioxidant enzyme (GST, GR, GPx, and SOD) activities after 24 h of exposure to UV-B with LD50 and half LD50 values. Also, expression patterns of p53 and hsp gene families with phosphorylation of p38 MAPK were investigated in UV-B-exposed copepods. We found that the ROS level, GSH content, and antioxidant enzyme activity levels were increased with the transcriptional upregulation of antioxidant-related genes, indicating that UV-B induces oxidative stress by generating ROS and stimulating antioxidant enzymatic activity as a defense mechanism. Additionally, we found that p53 expression was significantly increased after UV-B irradiation due to increases in the phosphorylation of the stress-responsive p38 MAPK, indicating that UV-B may be responsible for inducing DNA damage in T. japonicus. Of the hsp family genes, transcriptional levels of hsp20, hsp20.7, hsp70, and hsp90 were elevated in response to a low dose of UV-B radiation (9 kJ m(-2)), suggesting that these hsp genes may be involved in cellular protection against UV-B radiation. In this paper, we performed a pathway-oriented mechanistic analysis in response to UV-B radiation, and this analysis provides a better understanding of the effects of UV-B in the intertidal benthic copepod T. japonicus. Copyright © 2014 Elsevier Inc. All rights reserved.

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

EPA Science Inventory

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...

[Impact of the women's press on the attitudes of readers toward ultraviolet radiation--a survey of law and psychology students].

PubMed

Gałajda, Karolina; Kamińska-Winciorek, Grazyna; Spiewak, Radosław

2013-08-01

Excessive exposure to ultraviolet radiation (UVA and UVB) leads to negative consequences including sunburn, carcinogenesis and photoaging. Therefore, educational campaigns promoting safe tanning and sunscreens are necessary. Helpful with this regard might be mass media including women's magazines, which for young people are important source of information on health, beauty and lifestyle. The aim of the study was to examine the influence of women's press in the attitude of non-medical students toward ultraviolet radiation (UV) as well as to analyse articles about tanning and skin protection against UV rays in selected magazines for women. The study group consisted of 68 psychology students and 60 law students (n = 128). An original author's questionnaire was used in this research, including 22 questions regarding frequency of reading articles about sunbathing, and the impact of women's press on the respondents' attitude toward suntanning. In the second part of the study 13 articles were examined from magazines "Twój Styl", "ELLE", "PANI" (years 2007-2011), which contained keywords "sun", "tanning bed", "tanning", "UV radiation". Selected articles were assessed whether they were encouraging to, or discouraging from sunbathing. A majority (63%) of respondents declared that after reading the article in women's magazines, they began to apply a sunscreen with higher SPF rate than before. Moreover, 57% refrained from using tanbeds, and 48% began to regularly check melanocytic naevi and monitor their skin after sun exposures. The analysis of the articles showed that majority of articles discouraged from the sunbathing (11 articles discouraging versus and 2 encouraging). Women's press in Poland generally promotes women's rational behavior against UV radiation and tanning.

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

PubMed

Liu, Jie; Wang, Wen-Xiong

2017-09-01

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

Conidia survival of Aspergillus section Nigri, Flavi and Circumdati under UV-A and UV-B radiation with cycling temperature/light regime.

PubMed

García-Cela, Maria Esther; Marín, Sonia; Reyes, Monica; Sanchis, Vicent; Ramos, Antonio J

2016-04-01

Bio-geographical differences in fungal infection distribution have been observed around the world, confirming that climatic conditions are decisive in colonization. This research is focused on the impact of ultraviolet radiation (UV) on Aspergillus species, based on the consideration that an increase in UV-B radiation may have large ecological effects. Conidia of six mycotoxigenic Aspergillus species isolated from vineyards located in the northeast and south of Spain were incubated for 15 days under light/dark cycles and temperatures between 20 and 30 °C per day. Additionally, 6 h of exposure to UV-A or UV-B radiation per day were included in the light exposure. UV irradiance used were 1.7 ± 0.2 mW cm(-2) of UV-A (peak 365 nm) and 0.10 ± 0.2 mW cm(-2) of UV-B (peak 312 nm). The intrinsic decrease in viability of conidia over time was accentuated when they were UV irradiated. UV-B radiation was more harmful. Conidial sensitivity to UV light was marked in Aspergillus section Circumdati. Conidia pigmentation could be related to UV sensitivity. Different resistance was observed within species belonging to sections Flavi and Nigri. An increase in UV radiation could lead to a reduction in the Aspergillus spp. inoculum present in the field (vineyards, nuts, cereal crops). In addition, it could unbalance the spore species present in the field, leading to a higher predominance of dark-pigmented conidia. © 2015 Society of Chemical Industry.

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

PubMed

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

2011-08-01

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

Aureole radiance field about a source in a scattering-absorbing medium.

PubMed

Zachor, A S

1978-06-15

A technique is described for computing the aureole radiance field about a point source in a medium that absorbs and scatters according to an arbitrary phase function. When applied to an isotropic source in a homogenous medium, the method uses a double-integral transform which is evaluated recursively to obtain the aureole radiances contributed by successive scattering orders, as in the Neumann solution of the radiative transfer equation. The normalized total radiance field distribution and the variation of flux with field of view and range are given for three wavelengths in the uv and one in the visible, for a sea-level model atmosphere assumed to scatter according to a composite of the Rayleigh and modified Henyey-Greenstein phase functions. These results have application to the detection and measurement of uncollimated uv and visible sources at short ranges in the lower atmosphere.

Solar ultraviolet-B radiation and vitamin D: a cross-sectional population-based study using data from the 2007 to 2009 Canadian Health Measures Survey

PubMed Central

2012-01-01

Background Exposure to solar ultraviolet-B (UV-B) radiation is a major source of vitamin D3. Chemistry climate models project decreases in ground-level solar erythemal UV over the current century. It is unclear what impact this will have on vitamin D status at the population level. The purpose of this study was to measure the association between ground-level solar UV-B and serum concentrations of 25-hydroxyvitamin D (25(OH)D) using a secondary analysis of the 2007 to 2009 Canadian Health Measures Survey (CHMS). Methods Blood samples collected from individuals aged 12 to 79 years sampled across Canada were analyzed for 25(OH)D (n = 4,398). Solar UV-B irradiance was calculated for the 15 CHMS collection sites using the Tropospheric Ultraviolet and Visible Radiation Model. Multivariable linear regression was used to evaluate the association between 25(OH)D and solar UV-B adjusted for other predictors and to explore effect modification. Results Cumulative solar UV-B irradiance averaged over 91 days (91-day UV-B) prior to blood draw correlated significantly with 25(OH)D. Independent of other predictors, a 1 kJ/m2 increase in 91-day UV-B was associated with a significant 0.5 nmol/L (95% CI 0.3-0.8) increase in mean 25(OH)D (P = 0.0001). The relationship was stronger among younger individuals and those spending more time outdoors. Based on current projections of decreases in ground-level solar UV-B, we predict less than a 1 nmol/L decrease in mean 25(OH)D for the population. Conclusions In Canada, cumulative exposure to ambient solar UV-B has a small but significant association with 25(OH)D concentrations. Public health messages to improve vitamin D status should target safe sun exposure with sunscreen use, and also enhanced dietary and supplemental intake and maintenance of a healthy body weight. PMID:22894564

Formation of the center of ignition in a CH3Cl-Cl2 mixture under the action of UV light

NASA Astrophysics Data System (ADS)

Begishev, I. R.; Belikov, A. K.; Komrakov, P. V.; Nikitin, I. S.

2016-07-01

The dependence of temperature on time is investigated using a microthermocouple at different distances from a UV light source in a mixture of chlorine and chloromethane. These relationships give an idea of the size and location of a center of photoignition. It is found that if the size of the reaction vessel in the direction of the luminous flux is much greater than the dimensions of the ignition center, the thermal expansion of a reacting gas mixture has a huge impact on such photoignition parameters as the critical concentration limits and the critical intensity of UV radiation. It is found that by increasing the length of the vessel, some chlorinated combustible mixtures lose the ability to ignite when exposed to UV light.

UV filters for lighting of plants

NASA Astrophysics Data System (ADS)

Doehring, T.; Koefferlein, M.; Thiel, S.; Seidlitz, H. K.; Payer, H. D.

1994-03-01

The wavelength dependent interaction of biological systems with radiation is commonly described by appropriate action spectra. Particularly effective plant responses are obtained for ultraviolet (UV) radiation. Excess shortwave UV-B radiation will induce genetic defects and plant damage. Besides the ecological discussion of the deleterious effects of the excess UV radiation there is increasing interest in horticultural applications of this spectral region. Several metabolic pathways leading to valuable secondary plant products like colors, odors, taste, or resulting in mechanical strength and vitality are triggered by UV radiation. Thus, in ecologically as well as in economically oriented experiments the exact generation and knowledge of the spectral irradiance, particularly near the UV absorption edge, is essential. The ideal filter 'material' to control the UV absorption edge would be ozone itself. However, due to problems in controlling the toxic and chemically aggressive, instable gas, only rather 'small ozone filters' have been realized so far. In artificial plant lighting conventional solid filter materials such as glass sheets and plastic foils (celluloseacetate or cellulosetriacetate) which can be easily handled have been used to absorb the UV-C and the excess shortwave UV-B radiation of the lamp emissions. Different filter glasses are available which provide absorption properties suitable for gradual changes of the spectral UV-B illumination of artificial lighting. Using a distinct set of lamps and filter glasses an acceptable simulation of the UV-B part of natural global radiation can be achieved. The aging of these and other filter materials under the extreme UV radiation in the lamphouse of a solar simulator is presently unavoidable. This instability can be dealt with only by a precise spectral monitoring and by replacing the filters accordingly. For this reason attempts would be useful to develop real ozone filters which can replace glass filters. In any case chamber experiments require a careful selection of the filter material used and must be accompanied by a continuous UV-B monitoring.

UV filters for lighting of plants

NASA Technical Reports Server (NTRS)

Doehring, T.; Koefferlein, M.; Thiel, S.; Seidlitz, H. K.; Payer, H. D.

1994-01-01

The wavelength dependent interaction of biological systems with radiation is commonly described by appropriate action spectra. Particularly effective plant responses are obtained for ultraviolet (UV) radiation. Excess shortwave UV-B radiation will induce genetic defects and plant damage. Besides the ecological discussion of the deleterious effects of the excess UV radiation there is increasing interest in horticultural applications of this spectral region. Several metabolic pathways leading to valuable secondary plant products like colors, odors, taste, or resulting in mechanical strength and vitality are triggered by UV radiation. Thus, in ecologically as well as in economically oriented experiments the exact generation and knowledge of the spectral irradiance, particularly near the UV absorption edge, is essential. The ideal filter 'material' to control the UV absorption edge would be ozone itself. However, due to problems in controlling the toxic and chemically aggressive, instable gas, only rather 'small ozone filters' have been realized so far. In artificial plant lighting conventional solid filter materials such as glass sheets and plastic foils (celluloseacetate or cellulosetriacetate) which can be easily handled have been used to absorb the UV-C and the excess shortwave UV-B radiation of the lamp emissions. Different filter glasses are available which provide absorption properties suitable for gradual changes of the spectral UV-B illumination of artificial lighting. Using a distinct set of lamps and filter glasses an acceptable simulation of the UV-B part of natural global radiation can be achieved. The aging of these and other filter materials under the extreme UV radiation in the lamphouse of a solar simulator is presently unavoidable. This instability can be dealt with only by a precise spectral monitoring and by replacing the filters accordingly. For this reason attempts would be useful to develop real ozone filters which can replace glass filters. In any case chamber experiments require a careful selection of the filter material used and must be accompanied by a continuous UV-B monitoring.

Total ozone influence on the surface UV-B radiation in the late spring-summer 1963-1997: An analysis of multiple timescales

NASA Astrophysics Data System (ADS)

KrzyśCin, Janusz W.

2000-02-01

Monthly means and minima of total ozone for the late springs and summers (May-August) of 1963-1997 have been examined for the European Dobson stations (Arosa, Belsk, Hohenpeissenberg, Hradec Kralove, Uccle). It is shown that long-term tendencies in total ozone means were almost similar to those in the total ozone minima. Analyses of the late spring/summer means of UV daily doses, total ozone, and global solar radiation (proxy for the overall atmospheric transparency), measured at Belsk (52°N, 21°E) for the period 1976-1996, show that an importance of the total ozone changes for the UV-B level increases with the timescale. Decadal variations in total ozone are the main source of the UV trend at Belsk. Frequency of appearance of extreme daily total ozone values in the selected late spring/summer season seems to be important for analyses of the ozone forcing in the interannual timescale. Regional and temporal differences in the number of days with extreme low ozone values are discussed using the total ozone extrema taken at Arosa, Belsk, and Hradec Kralove in the 1963-1997 period. A statistical model is developed for diagnosis of the next day value of the UV-B level. The changes in the overall atmospheric transparency are essential for the UV-B level when the day-to-day variations in the UV forcing factors are examined.

[Ultraviolet exposure from indoor tanning devices as a potential source of health risks: Basic knowledge of the proper use of these devices for practical users, physicians and solarium staff].

PubMed

Malinowska-Borowska, Jolanta; Janosik, Elżbieta

2017-07-26

Bearing in mind the adverse health effects of exposure to ultraviolet (UV) radiation in solarium, especially the risk of carcinogenesis, there is a need to adopt legal regulations by relevant Polish authorities. They should set out the principles for indoor tanning studios operation, supervision and service of the technical parameters of tanning devices and training programs to provide the staff with professional knowledge and other aspects of safety in these facilities. The mechanism of the harmful effects of ultraviolet radiation on the human body, scale of overexposure, resulting from excessive sunbathing are described. Methods for estimating UV exposure and possible actions aimed at reducing the overexposure and preventing from cancer development caused by UV are also presented in this paper. Med Pr 2017;68(5):653-665. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

Optimized photodegradation of Bisphenol A in water using ZnO, TiO2 and SnO2 photocatalysts under UV radiation as a decontamination procedure

NASA Astrophysics Data System (ADS)

Abo, Rudy; Kummer, Nicolai-Alexeji; Merkel, Broder J.

2016-09-01

Experiments on photodegradation of Bisphenol A (BPA) were carried out in water samples by means photocatalytic and photo-oxidation methods in the presence of ZnO, TiO2 and SnO2 catalysts. The objective of this study was to develop an improved technique that can be used as a remediation procedure for a BPA-contaminated surface water and groundwater based on the UV solar radiation. The photodegradation of BPA in water performed under a low-intensity UV source mimics the UVC and UVA spectrum of solar radiation between 254 and 365 nm. The archived results reveal higher degradation rates observed in the presence of ZnO than with TiO2 and SnO2 catalysts during 20 h of irradiation. The intervention of the advanced photocatalytic oxidation (PCO) reduces the time of degradation to less than 1 h to reach a degradation rate of 90 % for BPA in water. The study proposes the use of ZnO as a competitor catalyst to the traditional TiO2, providing the most effective treatment of contaminated water with phenolic products.

[Effects of silicon supply on diurnal variations of physiological properties at rice heading stage under elevated UV-B radiation].

PubMed

Wu, Lei; Lou, Yun-sheng; Meng, Yan; Wang, Wei-qing; Cui, He-yang

2015-01-01

A pot experiment was conducted to investigate the effects of silicon (Si) supply on diurnal variations of photosynthesis and transpiration-related physiological parameters at rice heading stage under elevated UV-B radiation. The experiment was designed with two UV-B radiation levels, i.e. ambient UV-B. (ambient, A) and elevated UV-B (elevated by 20%, E), and four Si supply levels, i.e. Sio (control, 0 kg SiO2 . hm-2), Si, (sodium silicate, 100 kg SiO2 . hm-2), Si2 (sodium silicate, 200 kg SiO2 . hm2), Si3 (slag fertilizer, 200 kg SiO2 . hm-2). The results showed that, compared with ambient UV-B radiation, elevated UV-B radiation decreased the net photosynthesis rate (Pn) , intercellular CO2 concentration (Ci), transpiration rate (Tr), stomatal conductivity (gs) and water use efficiency (WUE) by 11.3%, 5.5%, 10.4%, 20.3% and 6.3%, respectively, in the treatment without Si supply (Si, level), and decreased the above parameters by 3.8%-5.5%, 0.7%-4.8%, 4.0%-8.7%, 7.4%-20.2% and 0.7%-5.9% in the treatments with Si supply (Si1, Si2 and Si3 levels) , respectively. Namely, elevated UV-B radiation decreased the photosynthesis and transpiration-related physiological parameters, but silicon supply could obviously mitigate the depressive effects of elevated UV-B radiation. Under elevated UV-B radiation, compared with control (Si0 level), silicon supply increased Pn, Ci, gs and WUE by 16.9%-28.0%, 3.5%-14.3%, 16.8% - 38.7% and 29.0% - 51.2%, respectively, but decreased Tr by 1.9% - 10.8% in the treatments with Si supply (Si1 , Si2 and Si3 levels). That is, silicon supply could mitigate the depressive effects of elevated UV-B radiation through significantly increasingnP., CigsgK and WUE, but decreasing T,. However, the difference existed in ameliorating the depressive effects of elevated UV-B radiation on diurnal variations of physiological parameters among the treatments of silicon supply, with the sequence of Si3>Si2>1i >Si0. This study suggested that fertilizing slag was helpful not only in recycling industrial wastes, but also in effectively mitigating the depressive effects of elevated UV-B radiation on photosynthesis and transpiration in rice production.

Ultraviolet damage to the eye revisited: eye-sun protection factor (E-SPF®), a new ultraviolet protection label for eyewear.

PubMed

Behar-Cohen, Francine; Baillet, Gilles; de Ayguavives, Tito; Garcia, Paula Ortega; Krutmann, Jean; Peña-García, Pablo; Reme, Charlotte; Wolffsohn, James S

2014-01-01

Ultraviolet (UV) radiation potentially damages the skin, the immune system, and structures of the eye. A useful UV sun protection for the skin has been established. Since a remarkable body of evidence shows an association between UV radiation and damage to structures of the eye, eye protection is important, but a reliable and practical tool to assess and compare the UV-protective properties of lenses has been lacking. Among the general lay public, misconceptions on eye-sun protection have been identified. For example, sun protection is mainly ascribed to sunglasses, but less so to clear lenses. Skin malignancies in the periorbital region are frequent, but usual topical skin protection does not include the lids. Recent research utilized exact dosimetry and demonstrated relevant differences in UV burden to the eye and skin at a given ambient irradiation. Chronic UV effects on the cornea and lens are cumulative, so effective UV protection of the eyes is important for all age groups and should be used systematically. Protection of children's eyes is especially important, because UV transmittance is higher at a very young age, allowing higher levels of UV radiation to reach the crystalline lens and even the retina. Sunglasses as well as clear lenses (plano and prescription) effectively reduce transmittance of UV radiation. However, an important share of the UV burden to the eye is explained by back reflection of radiation from lenses to the eye. UV radiation incident from an angle of 135°-150° behind a lens wearer is reflected from the back side of lenses. The usual antireflective coatings considerably increase reflection of UV radiation. To provide reliable labeling of the protective potential of lenses, an eye-sun protection factor (E-SPF®) has been developed. It integrates UV transmission as well as UV reflectance of lenses. The E-SPF® compares well with established skin-sun protection factors and provides clear messages to eye health care providers and to lay consumers.

Interactive effects of elevated ozone and UV-B radiation on soil nematode diversity.

PubMed

Bao, Xuelian; Li, Qi; Hua, Jianfeng; Zhao, Tianhong; Liang, Wenju

2014-01-01

Ultraviolet-B (UV-B) radiation and elevated tropospheric ozone may cause reductions in the productivity and quality of important agricultural crops. However, research regarding their interactive effect is still scarce, especially on the belowground processes. Using the open top chambers experimental setup, we monitored the response of soil nematodes to the elevated O3 and UV-B radiation individually as well as in combination. Our results indicated that elevated O3 and UV-B radiation have impact not only on the belowground biomass of plants, but also on the community structure and functional diversity of soil nematodes. The canonical correspondence analysis suggested that soil pH, shoot biomass and microbial biomass C and N were relevant parameters that influencing soil nematode distribution. The interactive effects of elevated O3 and UV-B radiation was only observed on the abundance of bacterivores. UV-B radiation significantly increased the abundance of total nematodes and bacterivores in comparison with the control at pod-filling stage of soybean. Following elevated O3, nematode diversity index decreased and dominance index increased relative to the control at pod-filling stage of soybean. Nematode functional diversity showed response to the effects of elevated O3 and UV-B radiation at pod-bearing stage. Higher enrichment index and lower structure index in the treatment with both elevated O3 and UV-B radiation indicated a stressed soil condition and degraded soil food web. However, the ratios of nematode trophic groups suggested that the negative effects of elevated O3 on soil food web may be weakened by the UV-B radiations.

Characterization of an Escherichia coli mutant (radB101) sensitive to. gamma. and uv radiation, and methyl methanesulfonate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sargentini, N.J.; Smith, K.C.

1983-03-01

After N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis of Escherichia coli K-12 (xthA14), an X-ray-sensitive mutant was isolated. This sensitivity is due to a mutation, radB101, which is located at 56.5 min on the E.coli K-12 linkage map. The radB101 mutation sensitized wild-type cells to ..gamma.. and uv radiation, and to methyl methanesulfonate. When known DNA repair-deficient mutants were ranked for their ..gamma..-radiation sensitivity relative to their uv-radiation sensitivity, their order was (starting with the most selectively ..gamma..-radiation-sensitive strain): recB21, radB101, wild type, polA1, recF143, lexA101, recA56, uvrD3, and uvrA6. The radB mutant was normal for ..gamma..- and uv-radiation mutagenesis, it showed only a slightmore » enhancement of ..gamma..- and uv-radiation-induced DNA degradation, and it was approx. 60% deficient in recombination ability. The radB gene is suggested to play a role in the recA gene-dependent (Type III) repair of DNA single-strand breaks after ..gamma.. irradiation and in postreplication repair after uv irradiation for the following reasons: the radB strain was normal for the host-cell reactivation of ..gamma..- and uv-irradiated bacteriophage lambda; the radB mutation did not sensitize a recA strain, but did sensitize a polA strain to ..gamma.. and uv radiation; the radB mutation sensitized a uvrB strain to uv radiation.« less

Feasibility of the silver-UV process for drinking water disinfection.

PubMed

Butkus, Michael A; Talbot, Mark; Labare, Michael P

2005-12-01

A synergistic effect between cationic silver and UV radiation (silver-UV disinfection) has been observed that can appreciably enhance inactivation of viruses. The purpose of this work was to assess the feasibility of this technique for drinking water disinfection and evaluate the effects of selected impurities, found in fresh water, and common parameters on inactivation of the coliphage MS-2 with the silver-UV process. Turbidity (kaolin), calcium hardness, carbonate alkalinity, and pH did not significantly degrade inactivation. Inactivation was reduced in the presence of chloride, at concentrations greater than 30 mg/L, and in water samples with UV-254 absorbance values greater than ca. 0.1 cm(-1). Inactivation of MS-2 with silver-UV disinfection was also reduced at high phosphate concentrations (above ca. 5 mM). Silver-UV inactivation of MS-2 increased with increases in temperature between 10 and 20 degrees C. Silver-UV inactivation of MS-2 was increased by greater than 1-log over UV alone, in two untreated fresh water sources, which indicates that silver-UV may be a viable treatment technology. An assessment of operation and management costs suggests that an increase in inactivation of MS-2 with silver-UV disinfection could be economically beneficial.

Life and the solar uv environment on the early Earth

NASA Astrophysics Data System (ADS)

Bérces, A.; Kovács, G.; Rontó, G.; Lammer, H.; Kargl, G.; Kömle, N.; Bauer, S.

2003-04-01

The solar UV radiation environment on planetary surfaces and within their atmospheres is of importance in a wide range of scientific disciplines. Solar UV radiation is the driving force of chemical and organic evolution and serves also as a constraint in biological evolution. Studies of the solar UV environment of the early Earth 2.0 Gyr to 3.8 Gyr ago suggest that the terrestrial atmosphere was essentially anoxic, resulting in an ozone column abundance insufficient for protecting the planetary surface in the UV-B and the UV-C ranges. Since, short wavelength solar UV radiation in the UV-B ind UV-C range penetrated through the unprotected atmosphere to the surface on early Earth, associated biological consequences may be expected. For DNA-based terrestrial solar UV dosimetry, bacteriophage T7, isolated phage-DNA ind polycrystalline Uracil samples have been used. The effect of solar UV radiation can be measured by detecting the biological-structural consequences of the damage induced by UV photons. We show model calculations for the Biological Effective Dose (BED) rate of Uracil and bacteriophage T7, for various ozone concentrations representing early atmospheric conditions on Earth up to a UV protecting ozone layer comparable to present times. Further, we discuss experimental data which show the photo-reverse effect of Uracil molecules caused by short UV wavelengths. These photoreversion effect highly depend on the wavelength of the radiation. Shorter wavelength UV radiation of about 200 nm is strongly effective in monomerisation, while the longer wavelengths prefer the production of dimerisation. We could demonstrate experimentally, for the case of an Uracil thin-layer that the photo-reaction process of the nucleotides can be both, dimerization and the reverse process: monomerization. These results are important for the study of solar UV exposure on organisms in the terrestrial environment more than 2 Gyr ago where Earth had no UV protecting ozone layer as well as for the search for life on Mars since we can show that biological harmful effects can also be reduced by shorter wavelength UV radiation, which is of importance in reducing DNA damages provoked by wavelengths longer than about 240 nm.

UV controlling factors and trends derived from the ground-based measurements taken at Belsk, Poland, 1976-1994

NASA Astrophysics Data System (ADS)

KrzyśCin, Janusz W.

1996-07-01

Monthly means of UV erythemal dose at ground level from the Robertson-Berger (RB) sunburn meter (1976-1992) and the UV-Biometer model 501 MED meter (1993-1994) located at Belsk (21°E, 52°N), Poland, are examined. The monthly means are calculated from all-sky daily means of UV erythemal dose. Ancillary measurements of column ozone (by Dobson spectrophotometer), sunshine duration (by Campbell-Stokes heliograph), and total (sun and sky) radiation (by a pyranometer) are considered to explain variations in the UV data. A multiple regression model is proposed to study trends in the UV data. The model accounts for the UV erythemal dose changes induced by total ozone, sunshine duration (surrogate for cloud cover variations), or total solar radiation (surrogate for combined cloud cover and atmospheric turbidity impact on the UV radiation), trends due to instrument drift, step changes in the data, and serial correlations. A strong relationship between monthly all-sky UV erythemal dose changes and total ozone (and total solar radiation) is found. Calculations show that an erythemal radiative amplification factor (RAF) due to ozone under all skies is close to its clear-sky value (about 1). However, the model gives evidence that the RAF due to ozone is smaller for cloudier (and/or more turbid) atmospheres than long-term reference. Total solar radiation change of 1% is associated with a change of 0.7% in the UV erythemal dose. Modeled trends in the Belsk's UV data, inferred from the model using ozone and total solar radiation as the UV forcing factors, are 2.3% ± 0.4% (1σ) per decade in the period 1976-1994. The large increase in the UV erythemal dose, of the order of 4% per decade due to ozone depletion (-3.2% per decade), is partially compensated by a decreasing tendency (-2.8% per decade) in total solar radiation. The model estimates the trend in the UV data of the order of 0.1% per decade (not statistically significant) due to superposition of the instrument drift and long-term effects related to other UV influencing factors (not parameterized by the model).

The effect of selenium and UV radiation on leaf traits and biomass production in Triticum aestivum L.

PubMed

Golob, Aleksandra; Kavčič, Jan; Stibilj, Vekoslava; Gaberščik, Alenka; Vogel-Mikuš, Katarina; Germ, Mateja

2017-02-01

UV radiation as an evolutionarily important environmental factor, significantly affects plants traits and alters the effects of other environmental factors. Single and combined effects of ambient UV radiation, its exclusion, and Se foliar treatments on Si concentrations and production of Si phytoliths in wheat (Triticum aestivum L.) cv. 'Reska' were studied. The effects of these treatments on growth parameters of the plants, structural and biochemical traits of the leaves, and interactions of the leaves with light, as Si incrustation is the first barrier to light at the leaf surface were also examined. Under ambient UV radiation and foliar treatment with 10mgL -1 sodium selenate solution, there was a trade-off between the plant investment in primary and secondary metabolism, as the production of UV-absorbing compounds was enhanced while photosynthetic pigment levels were reduced. Independent of Se treatment, ambient UV radiation lowered respiratory potential, Ca concentration, and leaf thickness, and increased Si concentration, Si phytoliths formation, and cuticle thickness. The Se treatment has little effect on plant traits and biomass production but it increased Se concentrations in the plants by >100-fold, independent of UV radiation. In combination with UV radiation Se strengthen the protection of plants against stress by increasing the amount of UV absorbing compounds, light reflectance and transmittance. Copyright © 2016 Elsevier Inc. All rights reserved.

Gene Expression Profiling in Response to Ultraviolet Radiation in Maize Genotypes with Varying Flavonoid Content1[w

PubMed Central

Casati, Paula; Walbot, Virginia

2003-01-01

Microarray hybridization was used to assess acclimation responses to four UV regimes by near isogenic maize (Zea mays) lines varying in flavonoid content. We found that 355 of the 2,500 cDNAs tested were regulated by UV radiation in at least one genotype. Among these, 232 transcripts are assigned putative functions, whereas 123 encode unknown proteins. UV-B increased expression of stress response and ribosomal protein genes, whereas photosynthesis-associated genes were down-regulated; lines lacking UV-absorbing pigments had more dramatic responses than did lines with these pigments, confirming the shielding role of these compounds. Sunlight filtered to remove UV-B or UV-B plus UV-A resulted in significant expression changes in many genes not previously associated with UV responses. Some pathways regulated by UV radiation are shared with defense, salt, and oxidative stresses; however, UV-B radiation can activate additional pathways not shared with other stresses. PMID:12913132

Study of UV radiation dose received by the Spanish population.

PubMed

Gurrea, Gonzalo; Cañada, Javier

2007-01-01

Excess exposure to UV radiation can affect our health by causing sunburn, skin cancer, etc. It is therefore useful to determine the UV dosage received by people as a way of protecting them from the possible negative effects that this kind of radiation can cause. In this work, the personal outdoor percentage, which shows the time spent in outdoor activities, as well as personal UV doses, has been calculated by means of global UV radiation on a horizontal plane. A database of average daily UVB radiation on the horizontal plane given by the National Institute of Meteorology has been used. In this work we evaluate the standard erythema dose of the Spanish population throughout the year.

Beneficial effects of solar UV-B radiation on soybean yield mediated by reduced insect herbivory under field conditions.

PubMed

Mazza, Carlos A; Giménez, Patricia I; Kantolic, Adriana G; Ballaré, Carlos L

2013-03-01

Ultraviolet-B radiation (UV-B: 280-315 nm) has damaging effects on cellular components and macromolecules. In plants, natural levels of UV-B can reduce leaf area expansion and growth, which can lead to reduced productivity and yield. UV-B can also have important effects on herbivorous insects. Owing to the successful implementation of the Montreal Protocol, current models predict that clear-sky levels of UV-B radiation will decline during this century in response to ozone recovery. However, because of climate change and changes in land use practices, future trends in UV doses are difficult to predict. In the experiments reported here, we used an exclusion approach to study the effects of solar UV-B radiation on soybean crops, which are extensively grown in many areas of the world that may be affected by future variations in UV-B radiation. In a first experiment, performed under normal management practices (which included chemical pest control), we found that natural levels of UV-B radiation reduced soybean yield. In a second experiment, where no pesticides were applied, we found that solar UV-B significantly reduced insect herbivory and, surprisingly, caused a concomitant increase in crop yield. Our data support the idea that UV-B effects on agroecosystems are the result of complex interactions involving multiple trophic levels. A better understanding of the mechanisms that mediate the anti-herbivore effect of UV-B radiation may be used to design crop varieties with improved adaptation to the cropping systems that are likely to prevail in the coming decades in response to agricultural intensification. Copyright © Physiologia Plantarum 2012.

Spectral transmittance of intraocular lenses under natural and artificial illumination: criteria analysis for choosing a suitable filter.

PubMed

Artigas, Jose M; Felipe, Adelina; Navea, Amparo; Artigas, Cristina; García-Domene, Maria C

2011-01-01

To compare the spectral transmission of different intraocular lenses (IOLs) with either ultraviolet (UV) or blue-light filters, and to analyze the performance of these filters with artificial light sources as well as sunlight. Experimental study. The spectral transmission curve of 10 IOLs was measured using a PerkinElmer Lambda 800 UV/VIS spectrometer (Waltham, MA). Different filtering simulations were performed using the D65 standard illuminant as daylight and standard incandescent lamp and fluorescent bulb illuminants. Spectral transmittance of the IOLs. All the IOLs studied provide good UVC (200-280 nm) and UVB (280-315 nm) protection, except for one that presented an appreciable window at 270 nm. Nevertheless, both natural and artificial sources have practically no emission under 300 nm. In the UVA (315-380 nm) range the curves of the different IOLs manifested different degrees of absorption. Not all the UV filters incorporated in different IOLs protect equally. The filters that provide greater photoprotection against UV radiation, even blue light, are yellow and orange. Then, yellow and orange IOL filters may be best suited for cases requiring special retinal protection. The filters that favor better photoreception of visible light (380-780 nm) are those that transmit this radiation close to 100%. Artificial illumination practically does not emit in the UV range, but its levels of illumination are very low when compared with solar light. A possible balance between photoprotection and photoreception could be a sharp cutoff filter with the cutoff wavelength near 400 nm and a maximum transmittance around 100%. Copyright © 2011 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Influence of clouds on UV-B penetration to the earth's surface

NASA Technical Reports Server (NTRS)

Green, A. E. S.

1979-01-01

Radiometric measurements of cloud influence on ultraviolet B radiation (UV-B) were obtained. Mathematical models of the influence were defined to lay the groundwork for the construction of the global UV-B climatology from satellite determined ozone data. More refined measurements comparing UV-B radiation with total solar radiation were carried out. The cloudy case is referred to the cloudless sky irradiance and convenient transmission ratios are given An approach to the inversion of scattering data is summarized. An improved characterization of the UV-B radiation from a cloudless sky is also presented.

Solar UV exposures measured simultaneously to all arbitrarily oriented leaves on a plant.

PubMed

Parisi, Alfio V; Schouten, Peter; Downs, Nathan J; Turner, Joanna

2010-05-03

The possible ramifications of climate change include the influence it has upon the amount of cloud cover in the atmosphere. Clouds cause significant variation in the solar UV radiation reaching the earth's surface and in turn the amount incident on ecosystems. The consequences of changes in solar UV radiation delivered to ecosystems due to climate change may be significant and should be investigated. Plants are an integral part of the world wide ecological balance, and research has shown they are affected by variations in solar UV radiation. Therefore research into the influence of solar UV radiation on plants is of particular significance. However, this requires a means of obtaining detailed information on the solar UV radiation received by plants. This research describes a newly developed dosimetric technique employed to gather information on solar UV radiation incident to the leaves of plants in combination with the measurement of spectral irradiances in order to provide an accurate method of collecting detailed information on the solar UV radiation affecting the canopy and lower leaf layers of individual plants. Variations in the measurements take into account the inclination and orientation of each leaf investigated, as well as the influence of shading by other leaves in the plant canopy. Copyright 2010 Elsevier B.V. All rights reserved.

UV RADIATION MEASUREMENTS/ATMOSPHERIC CHARACTERIZATION

EPA Science Inventory

Because exposure to ultraviolet (UV) radiation is an ecosystem stressor and poses a human health risk, the National Exposure Research Laboratory (NERL) has undertaken a research program to measure the intensity of UV-B radiation at various locations throughout the U.S. In Septem...

Enhanced UV-B radiation during pupal stage reduce body mass and fat content, while increasing deformities, mortality and cell death in female adults of solitary bee Osmia bicornis.

PubMed

Wasielewski, Oskar; Wojciechowicz, Tatiana; Giejdasz, Karol; Krishnan, Natraj

2015-08-01

The effects of enhanced UV-B radiation on the oogenesis and morpho-anatomical characteristics of the European solitary red mason bee Osmia bicornis L. (Hymenoptera: Megachilidae) were tested under laboratory conditions. Cocooned females in the pupal stage were exposed directly to different doses (0, 9.24, 12.32, and 24.64 kJ/m(2) /d) of artificial UV-B. Our experiments revealed that enhanced UV-B radiation can reduce body mass and fat body content, cause deformities and increase mortality. Following UV exposure at all 3 different doses, the body mass of bees was all significantly reduced compared to the control, with the highest UV dose causing the largest reduction. Similarly, following UV-B radiation, in treated groups the fat body index decreased and the fat body index was the lowest in the group receiving the highest dose of UV radiation. Mortality and morphological deformities, between untreated and exposed females varied considerably and increased with the dose of UV-B radiation. Morphological deformities were mainly manifested in the wings and mouthparts, and occurred more frequently with an increased dose of UV. Cell death was quantified by the Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay (DNA fragmentation) during early stages of oogenesis of O. bicornis females. The bees, after UV-B exposure exhibited more germarium cells with fragmented DNA. The TUNEL test indicated that in germarium, low doses of UV-B poorly induced the cell death during early development. However, exposure to moderate UV-B dose increased programmed cell death. In females treated with the highest dose of UV-B the vast majority of germarium cells were TUNEL-positive. © 2014 Institute of Zoology, Chinese Academy of Sciences.

Ultraviolet-induced responses in two species of climax tropical marine macrophytes.

PubMed

Detrés, Y; Armstrong, R A; Connelly, X M

2001-09-01

In tropical regions nominal reductions in stratospheric ozone could be detrimental to marine organisms that live near their upper tolerance levels of ultraviolet (UV) radiation and temperature. Well-known plant responses to UV include inhibition of photosynthesis, reductions in chlorophyll content, morphological changes and production of UV absorbing compounds such as flavonoids. An assessment of the effects and responses of two tropical marine macrophytes to full solar radiation and solar radiation depleted of UV were conducted in southwestern Puerto Rico. Changes in concentration of photosynthetic and photoprotective pigments, and in leaf optical properties of the red mangrove Rhizophora mangle and the seagrass Thalassia testudinum, were evaluated in field exclusion experiments. Rhizophora mangle exposed to full solar radiation showed lower leaf reflectance and a shift of 5 nm in the inflection point of the red edge. Thalassia testudinum samples excluded from UV had significant increases in total chlorophyll and carotenoid concentrations. These marine macrophytes showed increments in their concentration of UV-B absorbing compounds with exposure to UV radiation. Results indicate that even minor increases in UV radiation at low latitudes could have significant effects on the pigment composition of these climax species.

Establishing a ultraviolet radiation observational network and enhancing the study on ultraviolet radiation

NASA Astrophysics Data System (ADS)

Bai, Jianhui; Wang, Gengchen

2003-09-01

On the basis of analyzing observational data on solar radiation, meteorological parameters, and total ozone amount for the period of January 1990 to December 1991 in the Beijing area, an empirical calculation method for ultraviolet radiation (UV) in clear sky is obtained. The results show that the calculated values agree well with the observed, with maximum relative bias of 6.2% and mean relative bias for 24 months of 1.9%. Good results are also obtained when this method is applied in Guangzhou and Mohe districts. The long-term variation of UV radiation in clear sky over the Beijing area from 1979 to 1998 is calculated, and the UV variation trends and causes are discussed: direct and indirect UV energy absorption by increasing pollutants in the troposphere may have caused the UV decrease in clear sky in the last 20 years. With the enhancement of people’s quality of life and awareness of health, it will be valuable and practical to provid UV forecasts for typical cities and rural areas. So, we should develop and enhance UV study in systematic monitoring, forecasting, and developing a good and feasible method for UV radiation reporting in China, especially for big cities.

DAGON: a 3D Maxwell-Bloch code

NASA Astrophysics Data System (ADS)

Oliva, Eduardo; Cotelo, Manuel; Escudero, Juan Carlos; González-Fernández, Agustín.; Sanchís, Alberto; Vera, Javier; Vicéns, Sergio; Velarde, Pedro

2017-05-01

The amplification of UV radiation and high order harmonics (HOH) in plasmas is a subject of raising interest due to its different potential applications in several fields like environment and security (detection at distance), biology, materials science and industry (3D imaging) and atomic and plasma physics (pump-probe experiments). In order to develop these sources, it is necessary to properly understand the amplification process. Being the plasma an inhomogeneous medium which changes with time, it is desirable to have a full time-dependent 3D description of the interaction of UV and XUV radiation with plasmas. For these reasons, at the Instituto de Fusíon Nuclear we have developed DAGON, a 3D Maxwell-Bloch code capable of studying the full spationtemporal structure of the amplification process abovementioned.

Directional Degradation of Spectralon Diffuser Under Ionizing Radiation for Calibration of Space-Based Sensors

NASA Technical Reports Server (NTRS)

Georgiev, G. T.; Butler, J. J.; Kowalewski, M. G.; Ding, L.

2012-01-01

Assessment of the effect of Vacuum Ultra Violet (VUV) irradiation on the Bidirectional Reflectance Distribution Function (BRDF) of Spectralon is presented in this paper. The sample was a 99% white Spectralon calibration standard irradiated with VUV source positioned at 60o off the irradiation direction for a total of 20 hours. The BRDF before and after VUV irradiation was measured and compared at number of wavelengths in the UV, VIS and IR. Non-isotropic directional degradation of Spectralon diffuser under ionizing radiation was detected at different BRDF measurement geometries primarily at UV spectral range. The 8o directional/hemispherical reflectance of the same sample was also measured and compared from 200nm to 2500nm. Index Terms BRDF, Reflectance, Multiangular, Spectralon, Remote Sensing

Wire array K-shell sources on the SPHINX generator

NASA Astrophysics Data System (ADS)

D'Almeida, Thierry; Lassalle, Francis; Grunenwald, Julien; Maury, Patrick; Zucchini, Frédéric; Niasse, Nicolas; Chittenden, Jeremy

2014-10-01

The SPHINX machine is a LTD based Z-pinch driver operated by the CEA Gramat (France) and primarily used for studying K-shell radiation effects. We present the results of experiments carried out with single and nested large diameter aluminium wire array loads driven by a current of ~5 MA in ~800 ns. The dynamic of the implosion is studied with filtered X-UV time-integrated pin-hole cameras. The plasma electron temperature and the characteristics of the sources are estimated with time and spatially dependent spectrographs and PCDs. It is shown that Al K-shell yields (>1 keV) up to 27 kJ are obtained for a total radiation of ~ 230 kJ. These results are compared with simulations performed using the latest implementation of the non-LTE DCA code Spk in the 3D Eulerian MHD framework Gorgon developed at Imperial College. Filtered synthetic bolometers and PCD signals, time-dependent spatially integrated spectra and X-UV images are produced and show a good agreement with the experimental data. The capabilities of a prospective SPHINX II machine (20 MA ~ 800 ns) are also assessed for a wider variety of sources (Ti, Cu and W).

Modelling of the Saturnian Kilometric Radiation (SKR)

NASA Astrophysics Data System (ADS)

Cecconi, B.; Lamy, L.; Prangé, R.; Zarka, P.; Hess, S.; Clarke, J. T.; Nichols, J.

2008-12-01

The Saturnian Kilometric Radiation (SKR), discovered by the Voyager spacecraft in the 1980's, is observed quasi-continuously by Cassini since 2003. Study of 3 years of SKR observations by RPWS (Radio and Plasma Wave Science) revealed three recurrent features of SKR dynamic spectra : (i) discrete arcs, presumably caused by the anisotropy of the radio emission pattern combined to the observer's motion, (ii) an equatorial shadow zone around the planet (observed near perikrones) and (iii) signal extinctions at high northern latitudes. We model these features using the code PRES (Planetary Radio Emission Simulator) that assumes radio emissions to be generated via the Cyclotron Maser Instability for simulating observed dynamic spectra. We show that observed arc-like structures imply radio sources in partial (~90%) corotation, located on magnetic field lines of invariant latitude 70° to 75°, and emitting at oblique angle from the local magnetic field with a cone angle that varies with frequency. Then, based on the previously demonstrated conjugacy between UV and SKR sources, we successfully model the equatorial shadow zone as well as northern latitude SKR extinctions assuming time variable radio sources distributed along field lines with footprints along the daily UV oval measured from HST images.

The effect of UV radiation from oxygen and argon plasma on the adhesion of organosilicon coatings on polypropylene

NASA Astrophysics Data System (ADS)

Jaritz, M.; Behm, H.; Hopmann, Ch; Kirchheim, D.; Mitschker, F.; Awakowicz, P.; Dahlmann, R.

2017-01-01

The influence of ultraviolet (UV) radiation from oxygen and argon pretreatment plasmas on a plastic substrate has not been fully understood yet. In particular, its influence on the adhesion properties has not been sufficiently researched so far. This paper addresses this issue by comparing the bond strength of a plasmapolymerized silicon organic coating (SiO x C y H z ) on polypropylene (PP) after oxygen and argon plasma pretreatment and pretreatment by UV radiation emitted by the same plasmas. The UV radiation is isolated from the other species from the plasma by means of a magnesium fluoride (MgF2) optical filter. It could be shown that UV radiation originating from an oxygen plasma has a significant impact on both substrate surface chemistry and coating adhesion. The same maximum bond strength enhancement can be reached by pretreating the polypropylene surface either with pulsed oxygen plasma, or with only the UV radiation from this oxygen plasma. Also, similar surface chemistry and topography modifications are induced. For argon plasma no significant influence of its UV radiation on the substrate could be observed in this study.

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

PubMed

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

2018-01-01

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

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

PubMed Central

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

2018-01-01

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

Reconstruction of daily solar UV irradiation from 1893 to 2002 in Potsdam, Germany

NASA Astrophysics Data System (ADS)

Junk, Jürgen; Feister, Uwe; Helbig, Alfred

2007-08-01

Long-term records of solar UV radiation reaching the Earth’s surface are scarce. Radiative transfer calculations and statistical models are two options used to reconstruct decadal changes in solar UV radiation from long-term records of measured atmospheric parameters that contain information on the effect of clouds, atmospheric aerosols and ground albedo on UV radiation. Based on earlier studies, where the long-term variation of daily solar UV irradiation was derived from measured global and diffuse irradiation as well as atmospheric ozone by a non-linear regression method [Feister et al. (2002) Photochem Photobiol 76:281 293], we present another approach for the reconstruction of time series of solar UV radiation. An artificial neural network (ANN) was trained with measurements of solar UV irradiation taken at the Meteorological Observatory in Potsdam, Germany, as well as measured parameters with long-term records such as global and diffuse radiation, sunshine duration, horizontal visibility and column ozone. This study is focussed on the reconstruction of daily broad-band UV-B (280 315 nm), UV-A (315 400 nm) and erythemal UV irradiation (ER). Due to the rapid changes in cloudiness at mid-latitude sites, solar UV irradiance exhibits appreciable short-term variability. One of the main advantages of the statistical method is that it uses doses of highly variable input parameters calculated from individual spot measurements taken at short time intervals, which thus do represent the short-term variability of solar irradiance.

The consequences for human health of stratospheric ozone depletion in association with other environmental factors.

PubMed

Lucas, R M; Norval, M; Neale, R E; Young, A R; de Gruijl, F R; Takizawa, Y; van der Leun, J C

2015-01-01

Due to the implementation of the Montreal Protocol, which has limited, and is now probably reversing, the depletion of the stratospheric ozone layer, only modest increases in solar UV-B radiation at the surface of the Earth have occurred. For many fair-skinned populations, changing behaviour with regard to exposure to the sun over the past half century - more time in the sun, less clothing cover (more skin exposed), and preference for a tan - has probably contributed more to greater levels of exposure to UV-B radiation than ozone depletion. Exposure to UV-B radiation has both adverse and beneficial effects on human health. This report focuses on an assessment of the evidence regarding these outcomes that has been published since our previous report in 2010. The skin and eyes are the organs exposed to solar UV radiation. Excessive solar irradiation causes skin cancer, including cutaneous malignant melanoma and the non-melanoma skin cancers, basal cell carcinoma and squamous cell carcinoma, and contributes to the development of other rare skin cancers such as Merkel cell carcinoma. Although the incidence of melanoma continues to increase in many countries, in some locations, primarily those with strong sun protection programmes, incidence has stabilised or decreased over the past 5 years, particularly in younger age-groups. However, the incidence of non-melanoma skin cancers is still increasing in most locations. Exposure of the skin to the sun also induces systemic immune suppression that may have adverse effects on health, such as through the reactivation of latent viral infections, but also beneficial effects through suppression of autoimmune reactivity. Solar UV-B radiation damages the eyes, causing cataracts and pterygium. UV-B irradiation of the skin is the main source of vitamin D in many geographic locations. Vitamin D plays a critical role in the maintenance of calcium homeostasis in the body; severe deficiency causes the bone diseases, rickets in children and osteomalacia in adults. Although many studies have implicated vitamin D deficiency in a wide range of diseases, such as cancer and cardiovascular disease, more recent evidence is less compelling, with meta-analyses of supplementation trials failing to show a beneficial effect on the health outcomes that have been tested. It continues to be difficult to provide public health messages to guide safe exposure to the sun that are accurate, simple, and can be used by people with different skin types, in different locations, and for different times of the year or day. There is increasing interest in relating sun protection messages to the UV Index. Current sun protection strategies are outlined and assessed. Climatic factors affect the amount of UV radiation received by the skin and eyes, separately from the effect of ozone depletion. For example, cloud cover can decrease or increase the intensity of UV radiation at Earth's surface and warmer temperatures and changes in precipitation patterns may alter the amount of time people spend outdoors and their choice of clothing. The combination of changes in climate and UV radiation may affect the number of pathogenic microorganisms in surface waters, and could have an impact on food security through effects on plant and aquatic systems. It remains difficult to quantify these effects and their possible importance for human health.

The Response of Human Skin Commensal Bacteria as a Reflection of UV Radiation: UV-B Decreases Porphyrin Production

PubMed Central

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

2012-01-01

Recent global radiation fears reflect the urgent need for a new modality that can simply determine if people are in a radiation risk of developing cancer and other illnesses. Ultraviolet (UV) radiation has been thought to be the major risk factor for most skin cancers. Although various biomarkers derived from the responses of human cells have been revealed, detection of these biomarkers is cumbersome, probably requires taking live human tissues, and varies significantly depending on human immune status. Here we hypothesize that the reaction of Propionibacterium acnes (P. acnes), a human resident skin commensal, to UV radiation can serve as early surrogate markers for radiation risk because the bacteria are immediately responsive to radiation. In addition, the bacteria can be readily accessible and exposed to the same field of radiation as human body. To test our hypothesis, P. acnes was exposed to UV-B radiation. The production of porphyrins in P. acnes was significantly reduced with increasing doses of UV-B. The porphyrin reduction can be detected in both P. acnes and human skin bacterial isolates. Exposure of UV-B to P. acnes- inoculated mice led to a significant decrease in porphyrin production in a single colony of P. acnes and simultaneously induced the formation of cyclobutane pyrimidine dimers (CPD) in the epidermal layers of mouse skin. Mass spectrometric analysis via a linear trap quadrupole (LTQ)-Orbitrap XL showed that five peptides including an internal peptide (THLPTGIVVSCQNER) of a peptide chain release factor 2 (RF2) were oxidized by UV-B. Seven peptides including three internal peptides of 60 kDa chaperonin 1 were de-oxidized by UV-B. When compared to UV-B, gamma radiation also decreased the porphyrin production of P. acnes in a dose-dependent manner, but induced a different signature of protein oxidation/de-oxidation. We highlight that uncovering response of skin microbiome to radiation will facilitate the development of pre-symptomatic diagnosis of radiation risk in a battlefield exposure, nuclear accidents, terrorist attacks, or cancer imaging/therapy. PMID:23133525

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

PubMed

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

2012-01-01

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

Decontamination Efficacy of Ultraviolet Radiation against Biofilms of Common Nosocomial Bacteria.

PubMed

Tingpej, Pholawat; Tiengtip, Rattana; Kondo, Sumalee

2015-06-01

Ultraviolet radiation (UV) is commonly used to destroy microorganisms in the health-care environment. However, the efficacy of UV radiation against bacteria growing within biofilms has never been studied. To measure the sterilization effectiveness of UV radiation against common healthcare associated pathogens growing within biofilms. Staphylococcus aureus, Methicillin-resistant S. aureus (MRSA), Streptococcus epidermidis, Escherichia coli, ESBL-producing E. coli, Pseudomonas aeruginosa and Acinetobacter baumannii were cultivated in the Calgary Biofilm Device. Their biofilms were placed 50 cm from the UV lamp within the Biosafety Cabinet. Viability test, crystal violet assay and a scanning electron microscope were used to evaluate the germicidal efficacy. Within 5 minutes, UV radiation could kill S. aureus, MRSA, S. epidermidis, A. baumannii and ESBL-producing E. coli completely while it required 20 minutes and 30 minutes respectively to kill E. coli and P. aeruginosa. However, the amounts of biomass and the ultrastructure between UV-exposed biofilms and controls were not significantly different. UV radiation is effective in inactivating nosocomial pathogens grown within biofilms, but not removing biofilms and EPS. The biofilm of P. aeruginosa was the most durable.

Plant Responses to Increased UV-B Radiation: A Research Project

NASA Technical Reports Server (NTRS)

DAntoni, H. L.; Skiles, J. W.; Armstrong, R.; Coughlan, J.; Daleo, G.; Mayoral, A.; Lawless, James G. (Technical Monitor)

1994-01-01

Ozone decrease implies more ultraviolet-B (UV-B) radiation reaching the surface of the Earth. Increased UV-B radiation triggers responses by living organisms. Despite the large potential impacts on vegetation, little is known about UV-B effects on terrestrial ecosystems. Long-term ecological studies are needed to quantify the effects of increased UV radiation on terrestrial ecosystems, asses the risks, and produce reliable data for prediction. Screening pigments are part of one of the protective mechanism in plants. Higher concentrations of screening pigments in leaves may be interpreted as a response to increased UV radiation. If the screening effect is not sufficient, important molecules will be disturbed by incoming radiation. Thus, genetics, photosynthesis, growth, plant and leaf shape and size, and pollen grains may be affected. This will have an impact on ecosystem dynamics, structure and productivity. It is necessary to monitor selected terrestrial ecosystems to permit detection and interpretation of changes attributable to global climate change and depleted ozone shield. The objectives of this project are: (1) To identify and measure indicators of the effects of increased solar UV-B radiation on terrestrial plants; (2) to select indicators with the greatest responses to UV-B exposure; (3) to test, adapt or create ecosystem models that use the information gathered by this project for prediction and to enhance our understanding of the effects of increased UV-B radiation on terrestrial ecosystems. As a first step to achieve these objectives we propose a three-year study of forest and steppe vegetation on the North slope of the Brooks Range (within the Arctic circle, in Alaska), in the Saguaro National Monument (near Tucson, Arizona) and in the forests and steppes of Patagonia (Argentina). We selected (1) vegetation north of the Polar Circle because at 70N there is 8% risk of plant damage due to increased UV-B radiation; (2) the foothills of Catalina Mountains because there is anecdotal evidence of plant damage on the saguaros that has been linked to increased UV radiation, and (3) the forests of Nothofagus spp. and the steppe of Patagonia where the risk of plant damage at 35S is 5% and increases to as much as 15% at 55S due to increased UV-B radiation. Measurements of UV-B radiation impinging on the surface at 55S largely exceed the predicted UV-B radiation values at 50 latitude and 0% ozone depletion. Preliminary HPLC analyses of UV-B absorbing compounds in Nothofagus antartica, N. pumilio, N. betuloides and Rumex sp. in natural conditions show species-specific patterns. The spectrum of N. antartica grown at 38S differs significantly from that of N. antartica in natural conditions in Ushuaia (55S). These results suggest that the selected main area (Patagonia) is appropriate for assessing the problem and its magnitude and that Nothofagus is appropriate for our study.

Emission spectra of photoionized plasmas induced by intense EUV pulses: Experimental and theoretical investigations

NASA Astrophysics Data System (ADS)

Saber, Ismail; Bartnik, Andrzej; Skrzeczanowski, Wojciech; Wachulak, Przemysław; Jarocki, Roman; Fiedorowicz, Henryk

2017-03-01

Experimental measurements and numerical modeling of emission spectra in photoionized plasma in the ultraviolet and visible light (UV/Vis) range for noble gases have been investigated. The photoionized plasmas were created using laser-produced plasma (LPP) extreme ultraviolet (EUV) source. The source was based on a gas puff target; irradiated with 10ns/10J/10Hz Nd:YAG laser. The EUV radiation pulses were collected and focused using grazing incidence multifoil EUV collector. The laser pulses were focused on a gas stream, injected into a vacuum chamber synchronously with the EUV pulses. Irradiation of gases resulted in a formation of low temperature photoionized plasmas emitting radiation in the UV/Vis spectral range. Atomic photoionized plasmas produced this way consisted of atomic and ionic with various ionization states. The most dominated observed spectral lines originated from radiative transitions in singly charged ions. To assist in a theoretical interpretation of the measured spectra, an atomic code based on Cowan's programs and a collisional-radiative PrismSPECT code have been used to calculate the theoretical spectra. A comparison of the calculated spectral lines with experimentally obtained results is presented. Electron temperature in plasma is estimated using the Boltzmann plot method, by an assumption that a local thermodynamic equilibrium (LTE) condition in the plasma is validated in the first few ionization states. A brief discussion for the measured and computed spectra is given.

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

PubMed

Madronich, S; McKenzie, R L; Björn, L O; Caldwell, M M

1998-10-01

Stratospheric ozone levels are near their lowest point since measurements began, so current ultraviolet-B (UV-B) radiation levels are thought to be close to their maximum. Total stratospheric content of ozone-depleting substances is expected to reach a maximum before the year 2000. All other things being equal, the current ozone losses and related UV-B increases should be close to their maximum. Increases in surface erythemal (sunburning) UV radiation relative to the values in the 1970s are estimated to be: about 7% at Northern Hemisphere mid-latitudes in winter/spring; about 4% at Northern Hemisphere mid-latitudes in summer/fall; about 6% at Southern Hemisphere mid-latitudes on a year-round basis; about 130% in the Antarctic in spring; and about 22% in the Arctic in spring. Reductions in atmospheric ozone are expected to result in higher amounts of UV-B radiation reaching the Earth's surface. The expected correlation between increases in surface UV-B radiation and decreases in overhead ozone has been further demonstrated and quantified by ground-based instruments under a wide range of conditions. Improved measurements of UV-B radiation are now providing better geographical and temporal coverage. Surface UV-B radiation levels are highly variable because of cloud cover, and also because of local effects including pollutants and surface reflections. These factors usually decrease atmospheric transmission and therefore the surface irradiances at UV-B as well as other wavelengths. Occasional cloud-induced increases have also been reported. With a few exceptions, the direct detection of UV-B trends at low- and mid-latitudes remains problematic due to this high natural variability, the relatively small ozone changes, and the practical difficulties of maintaining long-term stability in networks of UV-measuring instruments. Few reliable UV-B radiation measurements are available from pre-ozone-depletion days. Satellite-based observations of atmospheric ozone and clouds are being used, together with models of atmospheric transmission, to provide global coverage and long-term estimates of surface UV-B radiation. Estimates of long-term (1979-1992) trends in zonally averaged UV irradiances that include cloud effects are nearly identical to those for clear-sky estimates, providing evidence that clouds have not influenced the UV-B trends. However, the limitations of satellite-derived UV estimates should be recognized. To assess uncertainties inherent in this approach, additional validations involving comparisons with ground-based observations are required. Direct comparisons of ground-based UV-B radiation measurements between a few mid-latitude sites in the Northern and Southern Hemispheres have shown larger differences than those estimated using satellite data. Ground-based measurements show that summertime erythemal UV irradiances in the Southern Hemisphere exceed those at comparable latitudes of the Northern Hemisphere by up to 40%, whereas corresponding satellite-based estimates yield only 10-15% differences. Atmospheric pollution may be a factor in this discrepancy between ground-based measurements and satellite-derived estimates. UV-B measurements at more sites are required to determine whether the larger observed differences are globally representative. High levels of UV-B radiation continue to be observed in Antarctica during the recurrent spring-time ozone hole. For example, during ozone-hole episodes, measured biologically damaging radiation at Palmer Station, Antarctica (64 degrees S) has been found to approach and occasionally even exceed maximum summer values at San Diego, CA, USA (32 degrees N). Long-term predictions of future UV-B levels are difficult and uncertain. Nevertheless, current best estimates suggest that a slow recovery to pre-ozone depletion levels may be expected during the next half-century. (ABSTRACT TRUNCATED)

Terrestrial ecosystems, increased solar ultraviolet radiation, and interactions with other climate change factors.

PubMed

Caldwell, M M; Bornman, J F; Ballaré, C L; Flint, S D; Kulandaivelu, G

2007-03-01

There have been significant advances in our understanding of the effects of UV-B radiation on terrestrial ecosystems, especially in the description of mechanisms of plant response. A further area of highly interesting research emphasizes the importance of indirect UV radiation effects on plants, pathogens, herbivores, soil microbes and ecosystem processes below the surface. Although photosynthesis of higher plants and mosses is seldom affected by enhanced or reduced UV-B radiation in most field studies, effects on growth and morphology (form) of higher plants and mosses are often manifested. This can lead to small reductions in shoot production and changes in the competitive balance of different species. Fungi and bacteria are generally more sensitive to damage by UV-B radiation than are higher plants. However, the species differ in their UV-B radiation sensitivity to damage, some being affected while others may be very tolerant. This can lead to changes in species composition of microbial communities with subsequent influences on processes such as litter decomposition. Changes in plant chemical composition are commonly reported due to UV-B manipulations (either enhancement or attenuation of UV-B in sunlight) and may lead to substantial reductions in consumption of plant tissues by insects. Although sunlight does not penetrate significantly into soils, the biomass and morphology of plant root systems of plants can be modified to a much greater degree than plant shoots. Root mass can exhibit sizeable declines with more UV-B. Also, UV-B-induced changes in soil microbial communities and biomass, as well as altered populations of small invertebrates have been reported and these changes have important implications for mineral nutrient cycling in the soil. Many new developments in understanding the underlying mechanisms mediating plant response to UV-B radiation have emerged. This new information is helpful in understanding common responses of plants to UV-B radiation, such as diminished growth, acclimation responses of plants to UV-B radiation and interactions of plants with consumer organisms such as insects and plant pathogens. The response to UV-B radiation involves both the initial stimulus by solar radiation and transmission of signals within the plants. Resulting changes in gene expression induced by these signals may have elements in common with those elicited by other environmental factors, and generate overlapping functional (including acclimation) responses. Concurrent responses of terrestrial systems to the combination of enhanced UV-B radiation and other global change factors (increased temperature, CO2, available nitrogen and altered precipitation) are less well understood. Studies of individual plant responses to combinations of factors indicate that plant growth can be augmented by higher CO2 levels, yet many of the effects of UV-B radiation are usually not ameliorated by the elevated CO2. UV-B radiation often increases both plant frost tolerance and survival under extreme high temperature conditions. Conversely, extreme temperatures sometimes influence the UV-B radiation sensitivity of plants directly. Plants that endure water deficit stress effectively are also likely to be tolerant of high UV-B flux. Biologically available nitrogen is exceeding historical levels in many regions due to human activities. Studies show that plants well supplied with nitrogen are generally more sensitive to UV-B radiation. Technical issues concerning the use of biological spectral weighting functions (BSWFs) have been further elucidated. The BSWFs, which are multiplication factors assigned to different wavelengths giving an indication of their relative biological effectiveness, are critical to the proper conduct and interpretation of experiments in which organisms are exposed to UV radiation, both in the field and in controlled environment facilities. The characteristics of BSWFs vary considerably among different plant processes, such 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.

Distinct physiological and metabolic reprogramming by highbush blueberry (Vaccinium corymbosum) cultivars revealed during long-term UV-B radiation.

PubMed

Luengo Escobar, Ana; Alberdi, Miren; Acevedo, Patricio; Machado, Mariana; Nunes-Nesi, Adriano; Inostroza-Blancheteau, Claudio; Reyes-Díaz, Marjorie

2017-05-01

Despite the Montreal protocol and the eventual recovery of the ozone layer over Antarctica, there are still concerns about increased levels of ultraviolet-B (UV-B) radiation in the Southern Hemisphere. UV-B induces physiological, biochemical and morphological stress responses in plants, which are species-specific and different even for closely related cultivars. In woody plant species, understanding of long-term mechanisms to cope with UV-B-induced stress is limited. Therefore, a greenhouse UV-B daily course simulation was performed for 21 days with two blueberry cultivars (Legacy and Bluegold) under UV-B BE irradiance doses of 0, 0.07 and 0.19 W m -2 . Morphological changes, photosynthetic performance, antioxidants, lipid peroxidation and metabolic features were evaluated. We found that both cultivars behaved differently under UV-B exposure, with Legacy being a UV-B-resistant cultivar. Interestingly, Legacy used a combined strategy: initially, in the first week of exposure its photoprotective compounds increased, coping with the intake of UV-B radiation (avoidance strategy), and then, increasing its antioxidant capacity. These strategies proved to be UV-B radiation dose dependent. The avoidance strategy is triggered early under high UV-B radiation in Legacy. Moreover, the rapid metabolic reprogramming capacity of this cultivar, in contrast to Bluegold, seems to be the most relevant contribution to its UV-B stress-coping strategy. © 2016 Scandinavian Plant Physiology Society.

Extreme-UV electrical discharge source

DOEpatents

Fornaciari, Neal R.; Nygren, Richard E.; Ulrickson, Michael A.

2002-01-01

An extreme ultraviolet and soft x-ray radiation electric capillary discharge source that includes a boron nitride housing defining a capillary bore that is positioned between two electrodes one of which is connected to a source of electric potential can generate a high EUV and soft x-ray radiation flux from the capillary bore outlet with minimal debris. The electrode that is positioned adjacent the capillary bore outlet is typically grounded. Pyrolytic boron nitride, highly oriented pyrolytic boron nitride, and cubic boron nitride are particularly suited. The boron nitride capillary bore can be configured as an insert that is encased in an exterior housing that is constructed of a thermally conductive material. Positioning the ground electrode sufficiently close to the capillary bore outlet also reduces bore erosion.

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

NASA Astrophysics Data System (ADS)

Omairi, Tareq; Wainwright, Milton

2015-07-01

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

Impact of UV-B radiation on the digestive enzymes and immune system of larvae of Indian major carp Catla catla.

PubMed

Sharma, Jaigopal; Rao, Y Vasudeva; Kumar, S; Chakrabarti, Rina

2010-03-01

Ultraviolet radiation is a potent threat to the aquatic animals. Exposure to such stressor affects metabolic and immunological processes. The present investigation aims to study the effect of UV-B radiation on digestive enzymes and immunity of larvae of Catla catla. Larvae were exposed to ultraviolet-B (UV-B, 280-320 nm) radiation (145 microW/cm(2)) for three different exposure times of 5, 10 and 15 min on every other day. After 55 days, important digestive enzymes were assayed. For immunological study, lysozyme, glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT) levels were measured. Then the fish were kept for one month without radiation and lysozyme level was measured. Protein concentration varied directly with the duration of exposure and was highest among fish that had received the 15 min UV-B irradiation. Significantly higher amylase, protease, trypsin and chymotrypsin activities were found in 5 min exposed fish compared to others. Lysozyme level was significantly higher in control group compared to the UV-B treated fish. The lysozyme level decreased with the increasing duration of UV-B radiation. When fish were kept without UV-B radiation for one month, lysozyme level was brought to the normal level in all treatments, except 15 min exposed fish. The GOT and GPT levels were significantly higher in the 15 min exposed group than others. The effects of UV-B radiation on the digestive physiology and immune system of catla have been clearly observed in the present study. The decreased enzyme activities in UV-B radiated fish results into improper digestion and poor growth.

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

PubMed

Meng, Xiangpeng; Chan, Wan

2017-02-15

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

UV-B Radiation Impacts Shoot Tissue Pigment Composition in Allium fistulosum L. Cultigens

PubMed Central

Abney, Kristin R.; Kopsell, Dean A.; Sams, Carl E.; Zivanovic, Svetlana; Kopsell, David E.

2013-01-01

Plants from the Allium genus are valued worldwide for culinary flavor and medicinal attributes. In this study, 16 cultigens of bunching onion (Allium fistulosum L.) were grown in a glasshouse under filtered UV radiation (control) or supplemental UV-B radiation [7.0 μmol·m−2 ·s−2 (2.68 W·m−2)] to determine impacts on growth, physiological parameters, and nutritional quality. Supplemental UV-B radiation influenced shoot tissue carotenoid concentrations in some, but not all, of the bunching onions. Xanthophyll carotenoid pigments lutein and β-carotene and chlorophylls a and b in shoot tissues differed between UV-B radiation treatments and among cultigens. Cultigen “Pesoenyj” responded to supplemental UV-B radiation with increases in the ratio of zeaxanthin + antheraxanthin to zeaxanthin + antheraxanthin + violaxanthin, which may indicate a flux in the xanthophyll carotenoids towards deepoxydation, commonly found under high irradiance stress. Increases in carotenoid concentrations would be expected to increase crop nutritional values. PMID:23606817

Effects of stratospheric ozone depletion, solar UV radiation, and climate change on biogeochemical cycling: interactions and feedbacks

DOE PAGES

Erickson III, David J.; Sulzberger, Barbara; Zepp, Richard G.; ...

2014-11-07

Climate change modulates the effects of solar UV radiation on biogeochemical cycles in terrestrial and aquatic ecosystems, particularly for carbon cycling, resulting in UV-mediated positive or negative feedbacks on climate. Possible positive feedbacks discussed in this assessment include: (i) enhanced UV-induced mineralisation of above ground litter due to aridification; (ii) enhanced UV-induced mineralisation of photoreactive dissolved organic matter (DOM) in aquatic ecosystems due to changes in continental runoff and ice melting; (iii) reduced efficiency of the biological pump due to UV-induced bleaching of coloured dissolved organic matter (CDOM) in stratified aquatic ecosystems, where CDOM protects phytoplankton from the damaging solarmore » UV-B radiation. Mineralisation of organic matter results in the production and release of CO 2, whereas the biological pump is the main biological process for CO 2 removal by aquatic ecosystems. This research also assesses the interactive effects of solar UV radiation and climate change on the biogeochemical cycling of aerosols and trace gases other than CO 2, as well as of chemical and biological contaminants. Lastly,, interacting effects of solar UV radiation and climate change on biogeochemical cycles are particularly pronounced at terrestrial-aquatic interfaces.« less

Effect of UV-C radiation on bioactive compounds of pineapple (Ananas comosus L. Merr.) by-products.

PubMed

Freitas, Ana; Moldão-Martins, Margarida; Costa, Helena S; Albuquerque, Tânia G; Valente, Ana; Sanches-Silva, Ana

2015-01-01

The industrial processing of pineapple generates a high quantity of by-products. To reduce the environmental impact of these by-products and the inherent cost of their treatment, it is important to characterise and valorise these products, converting them into high added value products. Ultra-violet radiation is one of the main sustainable sanitation techniques for fruits. Since this radiation can induce plant stress which can promote the biosynthesis of bioactive compounds, it is important to evaluate its effect in fruits. The amounts of vitamins (C and E) and carotenoids (α-carotene, β-carotene, β-cryptoxanthin, lutein, lycopene, neoxanthin, violaxanthin and zeaxanthin) in pineapple by-products (core and rind) were analysed before and after treatment with UV radiation. All treated and untreated pineapple by-products contained β-carotene as the main carotenoid (rind, 2537-3225 µg; and core, 960-994 µg 100 g(-1) DW). Pineapple rind also contained lutein (288-297 µg 100 g(-1) DW) and α-carotene (89-126 µg 100 g(-1) DW). The results provide evidence of the potential of pineapple by-products as a source of bioactive compounds with antioxidant activity, which can be used by pharmaceutical, cosmetics and food industries. In addition, UV-C was shown to be a treatment that can add nutritional value to pineapple by-products. © 2014 Society of Chemical Industry.

Potential effects of ultraviolet radiation reduction on tundra nitrous oxide and methane fluxes in maritime Antarctica.

PubMed

Bao, Tao; Zhu, Renbin; Wang, Pei; Ye, Wenjuan; Ma, Dawei; Xu, Hua

2018-02-27

Stratospheric ozone has begun to recover in Antarctica since the implementation of the Montreal Protocol. However, the effects of ultraviolet (UV) radiation on tundra greenhouse gas fluxes are rarely reported for Polar Regions. In the present study, tundra N 2 O and CH 4 fluxes were measured under the simulated reduction of UV radiation in maritime Antarctica over the last three-year summers. Significantly enhanced N 2 O and CH 4 emissions occurred at tundra sites under the simulated reduction of UV radiation. Compared with the ambient normal UV level, a 20% reduction in UV radiation increased tundra emissions by an average of 8 μg N 2 O m -2 h -1 and 93 μg CH 4 m -2 h -1 , whereas a 50% reduction in UV radiation increased their emissions by an average of 17 μg N 2 O m -2 h -1 and 128 μg CH 4 m -2 h -1 . No statistically significant correlation (P > 0.05) was found between N 2 O and CH 4 fluxes and soil temperature, soil moisture, total carbon, total nitrogen, NO 3 - -N and NH 4 + -N contents. Our results confirmed that UV radiation intensity is an important factor affecting tundra N 2 O and CH 4 fluxes in maritime Antarctica. Exclusion of the effects of reduced UV radiation might underestimate their budgets in Polar Regions with the recovery of stratospheric ozone.

Occupational Exposure to Ultraviolet Radiation and Risk of Non-Melanoma Skin Cancer in a Multinational European Study

PubMed Central

Surdu, Simona; Fitzgerald, Edward F.; Bloom, Michael S.; Boscoe, Francis P.; Carpenter, David O.; Haase, Richard F.; Gurzau, Eugen; Rudnai, Peter; Koppova, Kvetoslava; Févotte, Joëlle; Leonardi, Giovanni; Vahter, Marie; Goessler, Walter; Kumar, Rajiv; Fletcher, Tony

2013-01-01

Background Studies suggest that ambient sunlight plays an important role in the pathogenesis of non-melanoma skin cancers (NMSC). However, there is ongoing controversy regarding the relevance of occupational exposure to natural and artificial ultraviolet radiation (UV) radiation. Objectives We investigated potential associations between natural and artificial UV radiation exposure at work with NMSC in a case-control study conducted in Hungary, Romania, and Slovakia. Methods Occupational exposures were classified by expert assessment for 527 controls and 618 NMSC cases (515 basal cell carcinoma, BCC). Covariate information was collected via interview and multiple logistic regression models were used to assess associations between UV exposure and NMSC. Results Lifetime prevalence of occupational exposure in the participants was 13% for natural UV radiation and 7% for artificial UV radiation. Significant negative associations between occupational exposure to natural UV radiation and NMSC were detected for all who had ever been exposed (odds ratio (OR) 0.47, 95% confidence interval (CI) 0.27–0.80); similar results were detected using a semi-quantitative metric of cumulative exposure. The effects were modified by skin complexion, with significantly decreased risks of BCC among participants with light skin complexion. No associations were observed in relation to occupational artificial UV radiation exposure. Conclusions The protective effect of occupational exposure to natural UV radiation was unexpected, but limited to light-skinned people, suggesting adequate sun-protection behaviors. Further investigations focusing on variations in the individual genetic susceptibility and potential interactions with environmental and other relevant factors are planned. PMID:23638051

Development of UV-B screening compounds in response to variation in ambient levels of UV-B radiation

NASA Astrophysics Data System (ADS)

Sullivan, Joe H.; Xu, Chenping; Gao, Wei; Slusser, James R.

2005-08-01

The induction of UV-B screening compounds in response to exposure to UV-B radiation is a commonly reported response and is generally considered to be an adaptive response of plants for protection from UVinduced damage. However, a number of questions remain to be answered including the importance of qualitative and localization differences among species in providing protection, indirect consequences of changes in leaf secondary chemistry on ecological processes and the dose response of metabolite accumulation. In this study we utilized UV monitoring data provided on site by the USDA UV-B Monitoring and Research Program to monitor the changes in UV-screening compounds in soybeans under a range of UV-B levels due to natural variation in ambient UV-B radiation. Soybean cultivars Essex, Clark and Clark-magenta, an isoline of Clark that produces minimal levels of flavonols, were grown beneath shelters covered either with polyester to block most UV-B radiation or teflon which is nearly transparent in the UV range and harvested at regular intervals for pigment and protein analysis. Daily levels of weighted UV-B varied from <1 to >7 kJ m-2. Increases in UV-screening compounds showed a positive dose response to UV-B radiation in all cultivars with Essex showing the steepest dose response. UV-A also induced screening compounds in all species The hydroxycinnimates of the magenta isoline showed a steep dose response to UV-A and a rather constant (non dose specific) but small additional increment in response to UV-B. The Clark isoline, which produced primarily the flavonol quercetin, showed a dose response to UV-B intermediate between that of Clark-magenta and Essex. All three cultivars show similar tolerance to UV-B in field conditions indicating that UV-induced pigment production is adequate to protect them from excessive UV-B damage.

Ultraviolet stress delays chromosome replication in light/dark synchronized cells of the marine cyanobacterium Prochlorococcus marinus PCC9511

PubMed Central

2010-01-01

Background The marine cyanobacterium Prochlorococcus is very abundant in warm, nutrient-poor oceanic areas. The upper mixed layer of oceans is populated by high light-adapted Prochlorococcus ecotypes, which despite their tiny genome (~1.7 Mb) seem to have developed efficient strategies to cope with stressful levels of photosynthetically active and ultraviolet (UV) radiation. At a molecular level, little is known yet about how such minimalist microorganisms manage to sustain high growth rates and avoid potentially detrimental, UV-induced mutations to their DNA. To address this question, we studied the cell cycle dynamics of P. marinus PCC9511 cells grown under high fluxes of visible light in the presence or absence of UV radiation. Near natural light-dark cycles of both light sources were obtained using a custom-designed illumination system (cyclostat). Expression patterns of key DNA synthesis and repair, cell division, and clock genes were analyzed in order to decipher molecular mechanisms of adaptation to UV radiation. Results The cell cycle of P. marinus PCC9511 was strongly synchronized by the day-night cycle. The most conspicuous response of cells to UV radiation was a delay in chromosome replication, with a peak of DNA synthesis shifted about 2 h into the dark period. This delay was seemingly linked to a strong downregulation of genes governing DNA replication (dnaA) and cell division (ftsZ, sepF), whereas most genes involved in DNA repair (such as recA, phrA, uvrA, ruvC, umuC) were already activated under high visible light and their expression levels were only slightly affected by additional UV exposure. Conclusions Prochlorococcus cells modified the timing of the S phase in response to UV exposure, therefore reducing the risk that mutations would occur during this particularly sensitive stage of the cell cycle. We identified several possible explanations for the observed timeshift. Among these, the sharp decrease in transcript levels of the dnaA gene, encoding the DNA replication initiator protein, is sufficient by itself to explain this response, since DNA synthesis starts only when the cellular concentration of DnaA reaches a critical threshold. However, the observed response likely results from a more complex combination of UV-altered biological processes. PMID:20670397

Occupational skin cancer induced by ultraviolet radiation and its prevention.

PubMed

Diepgen, T L; Fartasch, M; Drexler, H; Schmitt, J

2012-08-01

Skin cancer is by far the most common kind of cancer diagnosed in many western countries and ultraviolet radiation is the most important risk factor for cutaneous squamous cell carcinoma (SCC) and basal cell carcinoma (BCC). Although employees at several workplaces are exposed to increased levels of UV radiation, skin cancer due to long-term intense occupational exposure to UV radiation is often not considered as occupational disease. The actually available evidence in the epidemiological literature clearly indicates that occupational UV radiation exposure is a substantial and robust risk factor for the development of cutaneous SCC and also clearly shows a significant risk for developing BCC. There is enough scientific evidence that outdoor workers have an increased risk of developing work-related occupational skin cancer due to natural UV radiation exposure and adequate prevention strategies must be implemented. The three measures which are successful and of particular importance in the prevention of nonmelanoma skin cancer in outdoor workers are changes in behaviour regarding awareness of health and disease resulting from exposure to natural UV radiation, protection from direct UV radiation by wearing suitable clothing, and regular and correct use of appropriate sunscreens. © 2012 The Authors. BJD © 2012 British Association of Dermatologists.

Next generation of Z* modelling tool for high intensity EUV and soft x-ray plasma sources simulations

NASA Astrophysics Data System (ADS)

Zakharov, S. V.; Zakharov, V. S.; Choi, P.; Krukovskiy, A. Y.; Novikov, V. G.; Solomyannaya, A. D.; Berezin, A. V.; Vorontsov, A. S.; Markov, M. B.; Parot'kin, S. V.

2011-04-01

In the specifications for EUV sources, high EUV power at IF for lithography HVM and very high brightness for actinic mask and in-situ inspections are required. In practice, the non-equilibrium plasma dynamics and self-absorption of radiation limit the in-band radiance of the plasma and the usable radiation power of a conventional single unit EUV source. A new generation of the computational code Z* is currently developed under international collaboration in the frames of FP7 IAPP project FIRE for modelling of multi-physics phenomena in radiation plasma sources, particularly for EUVL. The radiation plasma dynamics, the spectral effects of self-absorption in LPP and DPP and resulting Conversion Efficiencies are considered. The generation of fast electrons, ions and neutrals is discussed. Conditions for the enhanced radiance of highly ionized plasma in the presence of fast electrons are evaluated. The modelling results are guiding a new generation of EUV sources being developed at Nano-UV, based on spatial/temporal multiplexing of individual high brightness units, to deliver the requisite brightness and power for both lithography HVM and actinic metrology applications.

Ultraviolet damage to the eye revisited: eye-sun protection factor (E-SPF®), a new ultraviolet protection label for eyewear

PubMed Central

Behar-Cohen, Francine; Baillet, Gilles; de Ayguavives, Tito; Garcia, Paula Ortega; Krutmann, Jean; Peña-García, Pablo; Reme, Charlotte; Wolffsohn, James S

2014-01-01

Ultraviolet (UV) radiation potentially damages the skin, the immune system, and structures of the eye. A useful UV sun protection for the skin has been established. Since a remarkable body of evidence shows an association between UV radiation and damage to structures of the eye, eye protection is important, but a reliable and practical tool to assess and compare the UV-protective properties of lenses has been lacking. Among the general lay public, misconceptions on eye-sun protection have been identified. For example, sun protection is mainly ascribed to sunglasses, but less so to clear lenses. Skin malignancies in the periorbital region are frequent, but usual topical skin protection does not include the lids. Recent research utilized exact dosimetry and demonstrated relevant differences in UV burden to the eye and skin at a given ambient irradiation. Chronic UV effects on the cornea and lens are cumulative, so effective UV protection of the eyes is important for all age groups and should be used systematically. Protection of children’s eyes is especially important, because UV transmittance is higher at a very young age, allowing higher levels of UV radiation to reach the crystalline lens and even the retina. Sunglasses as well as clear lenses (plano and prescription) effectively reduce transmittance of UV radiation. However, an important share of the UV burden to the eye is explained by back reflection of radiation from lenses to the eye. UV radiation incident from an angle of 135°–150° behind a lens wearer is reflected from the back side of lenses. The usual antireflective coatings considerably increase reflection of UV radiation. To provide reliable labeling of the protective potential of lenses, an eye-sun protection factor (E-SPF®) has been developed. It integrates UV transmission as well as UV reflectance of lenses. The E-SPF® compares well with established skin-sun protection factors and provides clear messages to eye health care providers and to lay consumers. PMID:24379652

Unveiling slim accretion disc in AGN through X-ray and Infrared observations

NASA Astrophysics Data System (ADS)

Castelló-Mor, Núria; Kaspi, Shai; Netzer, Hagai; Du, Pu; Hu, Chen; Ho, Luis C.; Bai, Jin-Ming; Bian, Wei-Hao; Yuan, Ye-Fei; Wang, Jian-Min

2017-05-01

In this work, which is a continuation of Castelló-Mor et al., we present new X-ray and infrared (IR) data for a sample of active galactic nuclei (AGN) covering a wide range in Eddington ratio over a small luminosity range. In particular, we rigorously explore the dependence of the optical-to-X-ray spectral index αOX and the IR-to-optical spectral index on the dimensionless accretion rate, \\dot{M} = \\dot{m}/η, where \\dot{m} = LAGN/LEdd and η is the mass-to-radiation conversion efficiency, in low- and high-accretion rate sources. We find that the spectral energy distribution (SED) of the faster accreting sources is surprisingly similar to those from the comparison sample of sources with lower accretion rate. In particular: (I) The optical-to-UV AGN SED of slow and fast accreting AGN can be fitted with thin accretion disc (AD) models. (II) The value of αOX is very similar in slow and fast accreting systems up to a dimensionless accretion rate \\dot{M}c ˜ 10. We only find a correlation between αOX and \\dot{M} for sources with \\dot{M} > \\dot{M}c. In such cases, the faster accreting sources appear to have systematically larger αOX values. (III) We also find that the torus in the faster accreting systems seems to be less efficient in reprocessing the primary AGN radiation having lower IR-to-optical spectral slopes. These findings, failing to recover the predicted differences between the SEDs of slim and thin ADs within the observed spectral window, suggest that additional physical processes or very special geometry act to reduce the extreme-UV radiation in fast accreting AGN. This may be related to photon trapping, strong winds and perhaps other yet unknown physical processes.

Design of wideband solar ultraviolet radiation intensity monitoring and control system

NASA Astrophysics Data System (ADS)

Ye, Linmao; Wu, Zhigang; Li, Yusheng; Yu, Guohe; Jin, Qi

2009-08-01

According to the principle of SCM (Single Chip Microcomputer) and computer communication technique, the system is composed of chips such as ATML89C51, ADL0809, integrated circuit and sensors for UV radiation, which is designed for monitoring and controlling the UV index. This system can automatically collect the UV index data, analyze and check the history database, research the law of UV radiation in the region.

DC corona ozone generation enhanced by TiO2 photocatalyst

NASA Astrophysics Data System (ADS)

Pekã¡Rek, S.

2008-12-01

Non-thermal electrical discharges, such as corona discharge are apart of the source of ozone, charged, and excited species and acoustic noise also the source of electromagnetic radiation of different wavelengths. The important component of this radiation from the standpoint of photocatalyst activation is the ultraviolet radiation. We studied the role of UV radiation on corona discharge ozone production by placing the titanium dioxide photocatalyst into the discharge region. We used hollow needle to mesh DC corona discharge at atmospheric pressure with TiO2 globules on the mesh. The discharge was enhanced by the flow of air through the needle. We found that for the needle biased negatively addition of TiO2 photocatalyst on the mesh electrode drastically increases discharge ozone production as well as the ozone production yield. These quantities are also influenced by the mass of the used photocatalyst and its distribution in the discharge chamber.

Effects of Solar UV Radiation and Climate Change on Biogeochemical Cycling: Interactions and Feedbacks

EPA Science Inventory

Solar UV radiation, climate and other drivers of global change are undergoing significant changes and models forecast that these changes will continue for the remainder of this century. Here we assess the effects of solar UV radiation on biogeochemical cycles and the interactions...

PLANT PROTECTIVE RESPONSE TO ENHANCED UV-B RADIATION UNDER FIELD CONDITIONS: LEAF OPTICAL PROPERTIES AND PHOTOSYNTHESIS

EPA Science Inventory

Plants of Vicia faba were grown in the field during early to midsummer while receiving two levels of supplemental UV-B radiation. Light-saturated photosynthesis and stomatal diffusive conductance of intact leaves did not show any indications of UV-radiation damage. Supplemental U...

The solar spectral irradiances from x ray to radio wavelengths

NASA Technical Reports Server (NTRS)

White, O. R.

1993-01-01

Sources of new measurements of the solar EUV, UV, and visible spectrum are presented together with discussion of formation of the solar spectrum as a problem in stellar atmospheres. Agreement between the data and a modern synthetic spectrum shows that observed radiative variability is a minor perturbation on a photosphere in radiative equilibrium and local thermodynamic equilibrium (LTE). Newly observed solar variability in 1992 defines a magnetic episode on the Sun closely associated with changes in both spectral irradiances and the total irradiance. This episode offers the opportunity to track the relationship between radiation and magnetic flux evolution.

The Molecular and Physiological Responses of Physcomitrella patens to Ultraviolet-B Radiation1[W][OA

PubMed Central

Wolf, Luise; Rizzini, Luca; Stracke, Ralf; Ulm, Roman; Rensing, Stefan A.

2010-01-01

Ultraviolet-B (UV-B) radiation present in sunlight is an important trigger of photomorphogenic acclimation and stress responses in sessile land plants. Although numerous moss species grow in unshaded habitats, our understanding of their UV-B responses is very limited. The genome of the model moss Physcomitrella patens, which grows in sun-exposed open areas, encodes signaling and metabolic components that are implicated in the UV-B response in flowering plants. In this study, we describe the response of P. patens to UV-B radiation at the morphological and molecular levels. We find that P. patens is more capable of surviving UV-B stress than Arabidopsis (Arabidopsis thaliana) and describe the differential expression of approximately 400 moss genes in response to UV-B radiation. A comparative analysis of the UV-B response in P. patens and Arabidopsis reveals both distinct and conserved pathways. PMID:20427465

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

PubMed

Soriano-Melgar, Lluvia de Abril Alexandra; Alcaraz-Meléndez, Lilia; Méndez-Rodríguez, Lía C; Puente, María Esther; Rivera-Cabrera, Fernando; Zenteno-Savín, Tania

2014-05-01

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. To generate information on the effect of exposure to artificial UV-B radiation at different highdoses in the antioxidant content of damiana plants in an in vitro model. 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. 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. UV-B radiation modified the antioxidant content in damiana plants in an in vitro model, depending on the intensity and duration of the exposure. Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

Solar UV-B radiation modulates chemical defenses against Anticarsia gemmatalis larvae in leaves of field-grown soybean.

PubMed

Dillon, Francisco M; Chludil, Hugo D; Zavala, Jorge A

2017-09-01

Although it is well known that solar ultraviolet B (UV-B) radiation enhances plant defenses, there is less knowledge about traits that define insect resistance in field-grown soybean. Here we study the effects of solar UV-B radiation on: a) the induction of phenolic compounds and trypsin proteinase inhibitors (TPI) in soybean undamaged leaves or damaged by Anticarsia gemmatalis neonates during six days, and b) the survival and mass gain of A. gemmatalis larvae that fed on soybean foliage. Two soybean cultivars (cv.), Charata and Williams, were grown under plastic with different transmittance to solar UV-B radiation, which generated two treatments: ambient UV-B (UVB+) and reduced UV-B (UVB-) radiation. Solar UV-B radiation decreased survivorship by 30% and mass gain by 45% of larvae that fed on cv. Charata, but no effect was found in those larvae that fed on cv. Williams. TPI activity and malonyl genistin were induced by A. gemmatalis damage in both cultivars, but solar UV-B radiation and damage only synergistically increased the induction of these compounds in cv. Williams. Although TPI activity and genistein derivatives were induced by herbivory, these results did not explain the differences found in survivorship and mass gain of larvae that fed on cv. Charata. However, we found a positive association between lower larval performance and the presence of two quercetin triglycosides and a kaempferol triglycoside in foliage of cv. Charata, which were identified by HPLC-DAD/MS 2 . We conclude that exclusion of solar UV-B radiation reduce resistance to A. gemmatalis, due to a reduction in flavonol concentration in a cultivar that has low levels of genistein derivatives like cv. Charata. Copyright © 2017 Elsevier Ltd. All rights reserved.

Stress tolerance of soil fungal communities from native Atlantic forests, reforestations, and a sand mining degraded area.

PubMed

Ferreira, Paulo C; Pupin, Breno; Rangel, Drauzio E N

2018-06-01

Microorganisms are essential to the functionality of the soil, particularly in organic matter decomposition and nutrient cycling, which regulate plant productivity and shape the soil structure. However, biotic and abiotic stresses greatly disrupt soil fungal communities and, thereby, disturb the ecosystem. This study quantified seasonal tolerances to UV-B radiation and heat of fungal communities, which could be cultured, found in soil from two native Atlantic forest fragments called F1 and F2, five reforested areas (RA) planted in 1994, 1997, 2004, 2007, and 2009 with native species of the Atlantic forest, and one sand mining degraded soil (SMDS). The cold activity of the soil fungal communities (FC) from the eight different areas was also studied. Higher tolerance to UV-B radiation and heat was found in the FC from the SMDS and the 2009RA, where the incidence of heat and UV radiation from sun was more intense, which caused selection for fungal taxa that were more UV-B and heat tolerant in those areas. Conversely, the FC from the native forests and older reforested sites were very susceptible to heat and UV-B radiation. The cold activity of the soil FC from different areas of the study showed an erratic pattern of responses among the sampling sites. Little difference in tolerance to UV-B radiation and heat was found among the FC of soil samples collected in different seasons; in general soil FC collected in winter were less tolerant to UV-B radiation, but not for heat. In conclusion, FC from SMDS soil that receive intense heat and UV radiation, as well as with low nutrient availability, were more tolerant to both UV-B radiation and heat. Copyright © 2017 British Mycological Society. Published by Elsevier Ltd. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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

2016-08-01

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

Malvidin and cyanidin derivatives from açai fruit (Euterpe oleracea Mart.) counteract UV-A-induced oxidative stress in immortalized fibroblasts.

PubMed

Petruk, Ganna; Illiano, Anna; Del Giudice, Rita; Raiola, Assunta; Amoresano, Angela; Rigano, Maria Manuela; Piccoli, Renata; Monti, Daria Maria

2017-07-01

UV-A radiations are known to induce cellular oxidative stress, leading to premature skin aging. Consumption of açai fruit (Euterpe oleracea Martius) is known to have many health benefits due to its high level of antioxidants. Herein, we analyzed the ability of phenolic compounds extracted from this fruit to attenuate UV-A-induced oxidative stress in immortalized fibroblast. A methanol/water açai extract was fractionated by HPLC and each fraction tested for anti-oxidant stress activity. Immortalized fibroblasts were pre-incubated with açai fractions and then exposed to UV-A radiations. Açai extract was found to be able to strongly protect cells from oxidative stress. In particular, reactive oxygen species (ROS) production, GSH depletion, lipid peroxidation and no increase in the phosphorylation levels of proteins involved in the oxidative stress pathway was observed in cells pre-incubated with the extract and then irradiated by UV-A. Mass spectrometry analyses of HPLC fractionated extract led us to the identification of malvidin and cyanidin derivatives as the most active molecules able to counteract the negative effects induced by UV-A irradiation. Our results indicate, for the first time, that açai fruit is a valuable natural source for malvidin and cyanidin to be used as anti-stress molecules and represent good candidates for dietary intervention in the prevention of age related skin damage. Copyright © 2017 Elsevier B.V. All rights reserved.

Ultraviolet-B and photosynthetically active radiation interactively affect yield and pattern of monoterpenes in leaves of peppermint (Mentha x piperita L.).

PubMed

Behn, Helen; Albert, Andreas; Marx, Friedhelm; Noga, Georg; Ulbrich, Andreas

2010-06-23

Solar radiation is a key environmental signal in regulation of plant secondary metabolism. Since metabolic responses to light and ultraviolet (UV) radiation exposure are known to depend on the ratio of spectral ranges (e.g., UV-B/PAR), we examined effects of different UV-B radiation (280-315 nm) and photosynthetically active radiation (PAR, 400-700 nm) levels and ratios on yield and pattern of monoterpenoid essential oil of peppermint. Experiments were performed in exposure chambers, technically equipped for realistic simulation of natural climate and radiation. The experimental design comprised four irradiation regimes created by the combination of two PAR levels including or excluding UV-B radiation. During flowering, the highest essential oil yield was achieved at high PAR (1150 micromol m(-2) s(-1)) and approximate ambient UV-B radiation (0.6 W m(-2)). Regarding the monoterpene pattern, low PAR (550 micromol m(-2) s(-1)) and the absence of UV-B radiation led to reduced menthol and increased menthone contents and thereby to a substantial decrease in oil quality. Essential oil yield could not be correlated with density or diameter of peltate glandular trichomes, the epidermal structures specialized on biosynthesis, and the accumulation of monoterpenes. The present results lead to the conclusion that production of high quality oils (fulfilling the requirements of the Pharmacopoeia Europaea) requires high levels of natural sunlight. In protected cultivation, the use of UV-B transmitting covering materials is therefore highly recommended.

Responses of a marine red tide alga Skeletonema costatum (Bacillariophyceae) to long-term UV radiation exposures.

PubMed

Wu, Hongyan; Gao, Kunshan; Wu, Haiyan

2009-02-09

UV radiation (280-400 nm) is known to affect phytoplankton in negative, neutral and positive ways depending on the species or levels of irradiation energy. However, little has been documented on how photosynthetic physiology and growth of red tide alga respond to UVR in a long-term period. We exposed the cells of the marine red tide diatom Skeletonema costatum for 6 days to simulated solar radiations with UV-A (320-400 nm) or UV-A+UV-B (295-400 nm) and examined their changes in photosynthesis and growth. Presence of UV-B continuously reduced the effective photosynthetic quantum yield of PSII, and resulted in complete growth inhibition and death of cells. When UV-B or UV-B+UV-A was screened off, the growth rate decreased initially but regained thereafter. UV-absorbing compounds and carotenoids increased in response to the exposures with UVR. However, mechanisms for photoprotection associated with the increased carotenoids or UV-absorbing compounds were not adequate under the continuous exposure to a constant level of UV-B (0.09 Wm(-2), DNA-weighted). In contrast, under solar radiation screened off UV-B, the photoprotection was first accomplished by an initial increase of carotenoids and a later increase in UV-absorbing compounds. The overall response of this red tide alga to prolonged UV exposures indicates that S. costatum is a UV-B-sensitive species and increased UV-B irradiance would influence the formation of its blooms.

Artificial and Solar UV Radiation Induces Strand Breaks and Cyclobutane Pyrimidine Dimers in Bacillus subtilis Spore DNA

PubMed Central

Slieman, Tony A.; Nicholson, Wayne L.

2000-01-01

The loss of stratospheric ozone and the accompanying increase in solar UV flux have led to concerns regarding decreases in global microbial productivity. Central to understanding this process is determining the types and amounts of DNA damage in microbes caused by solar UV irradiation. While UV irradiation of dormant Bacillus subtilis endospores results mainly in formation of the “spore photoproduct” 5-thyminyl-5,6-dihydrothymine, genetic evidence indicates that an additional DNA photoproduct(s) may be formed in spores exposed to solar UV-B and UV-A radiation (Y. Xue and W. L. Nicholson, Appl. Environ. Microbiol. 62:2221–2227, 1996). We examined the occurrence of double-strand breaks, single-strand breaks, cyclobutane pyrimidine dimers, and apurinic-apyrimidinic sites in spore DNA under several UV irradiation conditions by using enzymatic probes and neutral or alkaline agarose gel electrophoresis. DNA from spores irradiated with artificial 254-nm UV-C radiation accumulated single-strand breaks, double-strand breaks, and cyclobutane pyrimidine dimers, while DNA from spores exposed to artificial UV-B radiation (wavelengths, 290 to 310 nm) accumulated only cyclobutane pyrimidine dimers. DNA from spores exposed to full-spectrum sunlight (UV-B and UV-A radiation) accumulated single-strand breaks, double-strand breaks, and cyclobutane pyrimidine dimers, whereas DNA from spores exposed to sunlight from which the UV-B component had been removed with a filter (“UV-A sunlight”) accumulated only single-strand breaks and double-strand breaks. Apurinic-apyrimidinic sites were not detected in spore DNA under any of the irradiation conditions used. Our data indicate that there is a complex spectrum of UV photoproducts in DNA of bacterial spores exposed to solar UV irradiation in the environment. PMID:10618224

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Laser-induced extreme UV radiation sources for manufacturing next-generation integrated circuits

NASA Astrophysics Data System (ADS)

Borisov, V. M.; Vinokhodov, A. Yu; Ivanov, A. S.; Kiryukhin, Yu B.; Mishchenko, V. A.; Prokof'ev, A. V.; Khristoforov, O. B.

2009-10-01

The development of high-power discharge sources emitting in the 13.5±0.135-nm spectral band is of current interest because they are promising for applications in industrial EUV (extreme ultraviolet) lithography for manufacturing integrated circuits according to technological precision standards of 22 nm and smaller. The parameters of EUV sources based on a laser-induced discharge in tin vapours between rotating disc electrodes are investigated. The properties of the discharge initiation by laser radiation at different wavelengths are established and the laser pulse parameters providing the maximum energy characteristics of the EUV source are determined. The EUV source developed in the study emits an average power of 276 W in the 13.5±0.135-nm spectral band on conversion to the solid angle 2π sr in the stationary regime at a pulse repetition rate of 3000 Hz.

SPATIAL AND TEMPORAL VARIABILITY IN THE AMOUNT AND SOURCE OF DISSOLVED ORGANIC CARBON: IMPLICATIONS FOR UV EXPOSURE IN AMPHIBIAN HABITS

EPA Science Inventory

Ultraviolet radiation (UVR) has been suggested as a potential cause of population declines and increases in malformations in amphibians. This study indicates that the present distributions of amphibians in four western U.S. National Parks are not related to UVR exposure and sugge...

Wavelength of ultraviolet radiation that enhances onset of clinical infectious bovine keratoconjunctivitis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kopecky, K.E.; Pugh, G.W. Jr.; Hughes, D.E.

1980-09-01

Cellulose acetate filtered ultraviolet (uv) radiation and unfiltered uv radiation were used on calves that were subsequently challenge exposed with Moraxella bovis. The onset, course, and severity of infectious bovine keratoconjunctivitis (IBK) were studied. Ten calves irradiated with unfiltered uv had the disease 1 to 2 days after M bovis challenge exposure. Ten calves irradiated with filtered uv and 10 calves not irradiated manifested IBK in a similar manner. Evidence is presented to support the contention that the wavelengths (around 270 nm) which are eliminated by cellulose acetate enhance the course of IBK. The effects on IBK of environmentally increasedmore » solar uv radiation is also discussed.« less

The dominant allele Aft induces a shift from flavonol to anthocyanin production in response to UV-B radiation in tomato fruit.

PubMed

Catola, Stefano; Castagna, Antonella; Santin, Marco; Calvenzani, Valentina; Petroni, Katia; Mazzucato, Andrea; Ranieri, Annamaria

2017-08-01

The introgression of the A ft allele into domesticated tomato induced a shift from flavonol to anthocyanin production in response to UV-B radiation, while the hp - 1 allele negatively influenced the response of flavonoid biosynthesis to UV-B. Introgression of the dominant allele Anthocyanin fruit (Aft) from Solanum chilense induces anthocyanin accumulation in the peel of tomato (Solanum lycopersicum L.) fruit. UV-B radiation can influence plant secondary metabolism regulating the expression of several genes, among which those involved in flavonoid biosynthesis. Here, we investigated whether post-harvest UV-B treatment could up-regulate flavonoid production in tomato fruits and whether the Aft allele could affect flavonoid biosynthesis under UV-B radiation. Mature green fruits of an anthocyanin-rich tomato mutant line (SA206) and of its wild-type reference, cv. Roma, were daily subjected to post-harvest UV-B treatment until full ripening. Up-regulation of CHS and CHI transcription by UV-B treatment induced flavonoid accumulation in the peel of cv. Roma. Conversely, UV-B decreased the total flavonoid content and CHS transcript levels in the SA206 peel. SA206 being a double mutant containing also hp-1 allele, we investigated also the behavior of hp-1 fruit. The decreased peel flavonoid accumulation and gene transcription in response to UV-B suggest that hp-1 allele is involved in the marked down-regulation of the flavonoid biosynthesis observed in SA206 fruit. Interestingly, in SA206, UV-B radiation promoted the synthesis of delphinidin, petunidin, and malvidin by increasing F3'5'H and DFR transcription, but it decreased rutin production, suggesting a switch from flavonols to anthocyanins. Finally, although UV-B radiation does not reach the inner fruit tissues, it down-regulated flavonoid biosynthesis in the flesh of both genotypes. This study provides, for the first time, evidence that the presence of the functional Aft allele, under UV-B radiation, redirects flavonoid synthesis towards anthocyanin production and suggests that the hp-1 allele negatively influences the response of flavonoid biosynthesis to UV-B.

Corneal NF-kappaB activity is necessary for the retention of transparency in the cornea of UV-B-exposed transgenic reporter mice.

PubMed

Alexander, George; Carlsen, Harald; Blomhoff, Rune

2006-04-01

To determine the dynamics of Nuclear Factor-kappaB (NF-kappaB) in murine corneal pathology and the role of NF-kappaB in maintaining corneal clarity after ultraviolet B radiation insult, transgenic mice containing NF-kappaB-luciferase reporter were exposed to LPS (bacterial lipopolysaccharide), TNF-alpha (Tumor Necrosis Factor-alpha) or 4 kJ m(-2) UV-B radiation. NF-kappaB decoy oligonucleotides were also administered in some of the UV-B experiments. Following various exposure times, the mice were sacrificed and whole eyes or corneal tissues were obtained. Whole eyes were examined for scattering using a point-source optical imaging technique. Tissue homogenates were examined for luciferase activity using a luminometer. TNF-alpha and LPS-injected NF-kappaB-luciferase transgenic mice demonstrated 3-10-fold increases in cornea NF-kappaB with peak activities at 4 and 6 hr post-injection, respectively. Mice exposed to 4 kJ m(-2) UV-B exhibited a 3-fold increase in NF-kappaB activity 4 hr post-exposure. The administration of NF-kappaB-decoy oligonucleotides to mice had the effect of reducing UV-B-induced NF-kappaB activity in the cornea and significantly increasing the amount of light scattering in UV-B exposed corneas 7 days post-UV-B exposure when compared to sham injected mice. These results indicate that NF-kappaB is activated in cornea in pathologies that involves increased plasma levels of LPS and TNF-alpha, as well as direct UV-B exposure, and suggest that NF-kappaB activation play an essential part in the corneal healing process.

UV Generation of 25 mJ/pulse at 289 nm for Ozone Lidar

NASA Technical Reports Server (NTRS)

Storm, Mark E.; Marsh, Waverly; Barnes, James C.

1998-01-01

Our paper describes a technique for generating tunable UV laser radiation between 250-300 nm capable of energies up to 30-5O mJ/pulse. The tunability of this source is attractive for selecting ozone absorption cross sections which are optimal for ozone DIAL detection throughout the troposphere. A Nd:YAG laser is used to pump a pulsed titanium sapphire laser which is then frequency tripled into the UV. Titanium sapphire (TiS) lases robustly between 750-900 nm. In initial experiments we have converted 110 mJ of 867 nm from a TiS laser into 28 mJ at 289 nm. The energy conversion efficiency was 62% for doubling into 433 nm and 25% into 289 nm.

Design of high power LED-based UVA emission system and a photosensitive substance for clinical application in corneal radiation

NASA Astrophysics Data System (ADS)

Mota, Alessandro D.; Cestari, André M.; de Oliveira, André O.; Oliveira, Anselmo G.; Terruggi, Cristina H. B.; Rossi, Giuliano; Castro, Jarbas C.; Ligabô, João. P. B.; Ortega, Tiago A.; Rosa, Tiago

2015-09-01

This work presents an innovative cross-linking procedure to keratoconus treatment, a corneal disease. It includes the development of an ultraviolet controlled emission portable device based on LED source and a new formulation of a photosensitive drug called riboflavin. Thus new formulation improves drug administration by its transepithelial property. The UV reaction with riboflavin in corneal tissue leads to a modification of corneal collagen fibers, turning them more rigid and dense, and consequently restraining the advance of the disease. We present the control procedures to maintain UV output power stable up to 45mw/cm2, the optical architecture that leads to a homogeneous UV spot and the new formulation of Riboflavin.

Enhanced resistance of the Pamirs high-mountain strain of Cryptococcus albidus to UV radiation of an ecological range

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strakhovskaya, M.G.; Lavrukhina, O.G.; Fraikin, G.Y.

The results of a comparative analysis of the resistance of Pamirs high-mountain and lowland strains of the yeast Cryptococcus albidus to UV radiation of an ecological range are presented. A high-mountain strain, adapted to elevated UV radiation in its habitat, was found to be more resistant to UV light of a total ecorange (290-400 nm), including medium-wave (290-320 nm) and long-wave (320-400 nm) UV ranges. The enhanced UV light resistance of the high-mountain strain can be explained by efficient functioning of the excision DNA repair system. 7 refs., 3 tabs.

UV radiation impacts body weight, oxygen consumption, and shelter selection in the intertidal vertebrate Girella laevifrons.

PubMed

Pulgar, José; Waldisperg, Melany; Galbán-Malagón, Cristóbal; Maturana, Diego; Pulgar, Victor M; Aldana, Marcela

2017-02-01

The amount of ultraviolet (UV) radiation reaching the earth's surface has increased due to ozone layer depletion, and this fact represents an opportunity to evaluate the physiological and behavioral responses of animals to this global-scale stressor. The transitory fish Girella laevifrons inhabits pools in the upper intertidal zone, which is characterized by exposure to a wide range of stressors, including UV radiation. We documented the field magnitude and the impact of UV radiation on oxygen consumption, body mass variations, and shelter (rocky and algae) selection by G. laevifrons. UV-exposed animals showed increased oxygen consumption, slower body weight increase, and active rocky shelter selection. Control fish showed increased body weight and no evident shelter selection. The results indicated that UV exposure affects fish energetic balance and habitat selection to favor greater protection against radiation. Increased UV exposure in transitory intertidal animals at levels observed in upper intertidal pools may alter the residency time of fish before leaving for the subtidal zone. Therefore, UV-induced energetic changes may determine animal performance and ontogenetic physiological itineraries, whereas shelter quality might determine habitat use. Copyright © 2016 Elsevier B.V. All rights reserved.

The novel cyclophilin D inhibitor compound 19 protects retinal pigment epithelium cells and retinal ganglion cells from UV radiation.

PubMed

Xie, Laiqing; Cheng, Long; Xu, Guoxu; Zhang, Ji; Ji, Xiaoyan; Song, E

2017-06-10

Excessive Ultra violet (UV) radiation induces injuries to retinal pigment epithelium (RPE) cells (RPEs) and retinal ganglion cells (RGCs), causing retinal degeneration. Cyclophilin D (Cyp-D)-dependent mitochondrial permeability transition pore (mPTP) opening mediates UV-induced cell death. In this study, we show that a novel Cyp-D inhibitor compound 19 efficiently protected RPEs and RGCs from UV radiation. Compound 19-mediated cytoprotection requires Cyp-D, as it failed to further protect RPEs/RGCs from UV when Cyp-D was silenced by targeted shRNAs. Compound 19 almost blocked UV-induced p53-Cyp-D mitochondrial association, mPTP opening and subsequent cytochrome C release. Further studies showed that compound 19 inhibited UV-induced reactive oxygen species (ROS) production, lipid peroxidation and DNA damage. Together, compound 19 protects RPEs and RGCs from UV radiation, possibly via silencing Cyp-D-regulated intrinsic mitochondrial death pathway. Compound 19 could a lead compound for treating UV-associated retinal degeneration diseases. Copyright © 2017 Elsevier Inc. All rights reserved.

Plasma Jet (V)UV-Radiation Impact on Biologically Relevant Liquids and Cell Suspension

NASA Astrophysics Data System (ADS)

Tresp, H.; Bussiahn, R.; Bundscherer, L.; Monden, A.; Hammer, M. U.; Masur, K.; Weltmann, K.-D.; Woedtke, Th. V.; Reuter, S.

2014-10-01

In this study the generation of radicals in plasma treated liquids has been investigated. To quantify the contribution of plasma vacuum ultraviolet (VUV) and ultraviolet (UV) radiation on the species investigated, three cases have been studied: UV of plasma jet only, UV and VUV of plasma jet combined, and the plasma effluent including all reactive components. The emitted VUV has been observed by optical emission spectroscopy and its effect on radical formation in liquids has been analyzed by electron spin resonance spectroscopy. Radicals have been determined in ultrapure water (dH2O), as well as in more complex, biorelevant solutions like phosphate buffered saline (PBS) solution, and two different cell culture media. Various compositions lead to different reactive species formation, e.g. in PBS superoxide anion and hydroxyl radicals have been detected, in cell suspension also glutathione thiyl radicals have been found. This study highlights that UV has no impact on radical generation, whereas VUV is relevant for producing radicals. VUV treatment of dH2O generates one third of the radical concentration produced by plasma-effluent treatment. It is relevant for plasma medicine because although plasma sources are operated in open air atmosphere, still VUV can lead to formation of biorelevant radicals. This work is funded by German Federal Ministry of Education a Research (BMBF) (Grant # 03Z2DN12+11).

Far-UV properties of the nuclear region of M31

NASA Technical Reports Server (NTRS)

King, Ivan R.; Stanford, S. Adam; Crane, Philippe

1995-01-01

Comparison of the Hubble Space Telescope (HST) far-UV and visible images of the nucleus of M31 deepens the mystery of the two brightness peaks recently discovered by Lauer et al. At 175 mm the brightest point is the optically fainter peak (P2) that is close to the dynamical center. The very center of P2 has a UV upturn that is much greater than that of the bulge light, while the UV upturn of the optically brighter but off-center P1 is very similar to that of its surroundings. The excess FUV radiation form P2 is closely confined to its center and has a total flux density of 3 micro-joules, a level that is less likely to come from stellar radiation than from a high-frequency extension of the radio source at the center of M31. A surrounding region of 1.8 pc radius has a somewhat smaller Uv upturn than the rest of the bulge, but there is some lingering possibility that this depression might be an artifact of our correction of the spherical aberration. Our improvement decomposition of the V image removes the need to postulate a dust lane near the center. We confirm that P1 is very compact, and we derive a luminosity for it similar to that found by Lauer et al. The implications of all of this are briefly discussed.

Energy and Emission Characteristics of a Short-Arc Xenon Flash Lamp Under "Saturated" Optical Brightness Conditions

NASA Astrophysics Data System (ADS)

Kamrukov, A. S.; Kireev, S. G.; Kozlov, N. P.; Shashkovskii, S. G.

2017-09-01

We present the results of a study of the electrical, energy, and spectral brightness characteristics of an experimental three-electrode high-pressure xenon flash lamp under conditions ensuring close to maximum possible spectral brightness for the xenon emission. We show that under saturated optical brightness conditions (brightness temperature in the visible region of the spectrum 30,000 K), emission of a pulsed discharge in xenon is quite different from the emission from an ideal blackbody: the maximum brightness temperatures are 24,000 K in the short-wavelength UV region and 19,000 K in the near IR range. The relative fraction of UV radiation in the emission spectrum of the lamp is >50%, which lets us consider such lamps as promising broadband sources of radiation with high spectral brightness for many important practical applications.

The linear polarization of 3C 345 in the ultraviolet

NASA Technical Reports Server (NTRS)

Dolan, Joseph F.; Boyd, Patricia T.; Wolinski, Karen G.; Smith, Paul S.; Impey, C. D.; Bless, Robert C.; Nelson, M. J.; Percival, J. W.; Taylor, M. J.; Elliot, J. L.

1994-01-01

The linear polarization of 3C 345, a superluminal radio source and OVV quasar, was observed in two bandpasses in the ultraviolet (centered at 2160 A and 2770 A) in 1993 April using the High Speed Photometer on the Hubble Space Telescope. The quasar is significantly polarized in the UV (p greater than 5%). Ground-based polarimetry was obtained 11 days later, but a difference in the position angle between the observations in the visible and those in the UV indicate that the magnitude of the polarization of 3C 345 may have changed over that time. If the two observation sets represent the same state of spectral polarization, then the large UV flux implies that either the polarization of the synchrotron continuum must stop decreasing in the UV, or that there is an additional source of polarized flux in the ultraviolet. Only if the UV observations represent a spectral polarization state with the same position angle in the visible seen previously in 3C 345 can the polarized flux be represented by a single power law consistent with the three-component model of Smith et al. This model consists of a polarized synchrotron component, an unpolarized component from the broad-line region, and an unpolarized component attributed to thermal radiation from an optically thick accretion disk. Additional simultaneous polarimetry in the UV and visible will be required to further constrain models of the continuum emission processes in 3C 345 and determine if the UV polarized flux is synchrotron in origin.

Analysis of UV-absorbing photoprotectant mycosporine-like amino acid (MAA) in the cyanobacterium Arthrospira sp. CU2556.

PubMed

Rastogi, Rajesh P; Incharoensakdi, Aran

2014-07-01

Mycosporine-like amino acids (MAAs) are ecologically important biomolecules with great photoprotective potential. The present study aimed to investigate the biosynthesis of MAAs in the cyanobacterium Arthrospira sp. CU2556. High-performance liquid chromatography (HPLC) with photodiode-array detection studies revealed the presence of a UV-absorbing compound with an absorption maximum at 310 nm. Based on its UV absorption spectrum and ion trap liquid chromatography/mass spectrometry (LC/MS) analysis, the compound was identified as a primary MAA mycosporine-glycine (m/z: 246). To the best of our knowledge this is the first report on the occurrence of MAA mycosporine-glycine (M-Gly) in Arthrospira strains studied so far. In contrast to photosynthetic activity under UV-A radiation, the induction of the biosynthesis of M-Gly was significantly more prominent under UV-B radiation. The content of M-Gly was found to increase with the increase in exposure time under UV-B radiation. The MAA M-Gly was highly stable under UV radiation, heat, strongly acidic and alkaline conditions. It also exhibited good antioxidant activity and photoprotective ability by detoxifying the in vivo reactive oxygen species (ROS) generated by UV radiation. Our results indicate that the studied cyanobacterium may protect itself by synthesizing the UV-absorbing/screening compounds as important defense mechanisms, in their natural brightly-lit habitat with high solar UV-B fluxes.

Manipulating Sensory and Phytochemical Profiles of Greenhouse Tomatoes Using Environmentally Relevant Doses of Ultraviolet Radiation.

PubMed

Dzakovich, Michael P; Ferruzzi, Mario G; Mitchell, Cary A

2016-09-14

Fruits harvested from off-season, greenhouse-grown tomato plants have a poor reputation compared to their in-season, garden-grown counterparts. Presently, there is a gap in knowledge with regard to the role of UV-B radiation (280-315 nm) in determining greenhouse tomato quality. Knowing that UV-B is a powerful elicitor of secondary metabolism and not transmitted through greenhouse glass and some greenhouse plastics, we tested the hypothesis that supplemental UV-B radiation in the greenhouse will impart quality attributes typically associated with garden-grown tomatoes. Environmentally relevant doses of supplemental UV-B radiation did not strongly affect antioxidant compounds of fruits, although the flavonol quercetin-3-O-rutinoside (rutin) significantly increased in response to UV-B. Physicochemical metrics of fruit quality attributes and consumer sensory panels were used to determine if any such differences altered consumer perception of tomato quality. Supplemental UV-A radiation (315-400 nm) pre-harvest treatments enhanced sensory perception of aroma, acidity, and overall approval, suggesting a compelling opportunity to environmentally enhance the flavor of greenhouse-grown tomatoes. The expression of the genes COP1 and HY5 were indicative of adaptation to UV radiation, which explains the lack of marked effects reported in these studies. To our knowledge, these studies represent the first reported use of environmentally relevant doses of UV radiation throughout the reproductive portion of the tomato plant life cycle to positively enhance the sensory and chemical properties of fruits.

Increased antioxidant activity and changes in phenolic profile of Kalanchoe pinnata (Lamarck) Persoon (Crassulaceae) specimens grown under supplemental blue light.

PubMed

Nascimento, Luana B S; Leal-Costa, Marcos V; Coutinho, Marcela A S; Moreira, Nattacha dos S; Lage, Celso L S; Barbi, Nancy dos S; Costa, Sônia S; Tavares, Eliana S

2013-01-01

Antioxidant compounds protect plants against oxidative stress caused by environmental conditions. Different light qualities, such as UV-A radiation and blue light, have shown positive effects on the production of phenols in plants. Kalanchoe pinnata (Lamarck) Persoon (Crassulaceae) is used for treating wounds and inflammations. Some of these beneficial effects are attributed to the antioxidant activity of plant components. We investigated the effects of blue light and UV-A radiation supplementation on the total phenol content, antioxidant activity and chromatographic profile of aqueous extracts from leaves of K. pinnata. Monoclonal plants were grown under white light, white plus blue light and white plus UV-A radiation. Supplemental blue light improved the antioxidant activity and changed the phenolic profile of the extracts. Analysis by HPLC of supplemental blue-light plant extracts revealed a higher proportion of the major flavonoid quercetin 3-O-α-L-arabinopyranosyl (1→2) α-L-rhamnopyranoside, as well as the presence of a wide variety of other phenolic substances. These findings may explain the higher antioxidant activity observed for this extract. Blue light is proposed as a supplemental light source in the cultivation of K. pinnata, to improve its antioxidant activity. © 2012 Wiley Periodicals, Inc. Photochemistry and Photobiology © 2012 The American Society of Photobiology.

Cerenkov radiation-induced phototherapy for depth-independent cancer treatment (Conference Presentation)

NASA Astrophysics Data System (ADS)

Akers, Walter J.; Achilefu, Samuel; Kotagiri, Nalinikanth

2017-02-01

Light emitted as the result of high-energy particle transport through biological tissues (Cerenkov radiation) can be exploited for noninvasive diagnostic imaging using high sensitivity scientific cameras. We have investigated the energy transfer potential of Cerenkov radiation, discovering a new phototherapeutic technique for treatment of localized and disseminated cancers. This technique, Cerenkov radiation-induced phototherapy (CRIT), like photodynamic therapy, requires the presence of both light and photosensitive agent together to induce cytotoxicity and effective cancer treatment. But unlike conventional phototherapy strategies in which tissue ablation or activation of photoactive molecules is limited to superficial structures, radiation-induced phototherapy enables phototherapy delivery to the tumor sites throughout the body. Titanium oxide nanoparticles, which produce cytotoxic reactive oxygen species upon irradiation with UV light, were targeted to tumor tissue by surface decoration with transferrin. Subsequent administration of tumor-avid radiotracer, 18-fluorodeoxyglucose (18FDG) provided localized UV light source via Cerenkov radiation. Treatment of tumor-bearing mice with the combination of Titanium nanoparticles and 18FDG resulted in effective reduction in tumor growth, while individual agents were not therapeutic. This new strategy in cancer therapy extends the reach of phototherapy beyond what was previously possible, with potential for treatment of cancer metastases and rescue from treatment resistance.

APEX-CHAMP+ high-J CO observations of low-mass young stellar objects. IV. Mechanical and radiative feedback

NASA Astrophysics Data System (ADS)

Yıldız, U. A.; Kristensen, L. E.; van Dishoeck, E. F.; Hogerheijde, M. R.; Karska, A.; Belloche, A.; Endo, A.; Frieswijk, W.; Güsten, R.; van Kempen, T. A.; Leurini, S.; Nagy, Z.; Pérez-Beaupuits, J. P.; Risacher, C.; van der Marel, N.; van Weeren, R. J.; Wyrowski, F.

2015-04-01

Context. During the embedded stage of star formation, bipolar molecular outflows and UV radiation from the protostar are important feedback processes. Both processes reflect the accretion onto the forming star and affect subsequent collapse or fragmentation of the cloud. Aims: Our aim is to quantify the feedback, mechanical and radiative, for a large sample of low-mass sources in a consistent manner. The outflow activity is compared to radiative feedback in the form of UV heating by the accreting protostar to search for correlations and evolutionary trends. Methods: Large-scale maps of 26 young stellar objects, which are part of the Herschel WISH key program are obtained using the CHAMP+ instrument on the Atacama Pathfinder EXperiment (12CO and 13CO 6-5; Eup ~ 100 K), and the HARP-B instrument on the James Clerk Maxwell Telescope (12CO and 13CO 3-2; Eup ~ 30 K). The maps have high spatial resolution, particularly the CO 6-5 maps taken with a 9″ beam, resolving the morphology of the outflows. The maps are used to determine outflow parameters and the results are compared with higher-J CO lines obtained with Herschel. Envelope models are used to quantify the amount of UV-heated gas and its temperature from 13CO 6-5 observations. Results: All sources in our sample show outflow activity, with the spatial extent decreasing from the Class 0 to the Class I stage. Consistent with previous studies, the outflow force, FCO, is larger for Class 0 sources than for Class I sources, even if their luminosities are comparable. The outflowing gas typically extends to much greater distances than the power-law envelope and therefore influences the surrounding cloud material directly. Comparison of the CO 6-5 results with HIFI H2O and PACS high-J CO lines, both tracing currently shocked gas, shows that the two components are linked, even though the transitions do not probe the same gas. The link does not extend down to CO 3-2. The conclusion is that CO 6-5 depends on the shock characteristics (density and velocity), whereas CO 3-2 is more sensitive to conditions in the surrounding environment (density). The radiative feedback is responsible for increasing the gas temperature by a factor of two, up to 30-50 K, on scales of a few thousand AU, particularly along the direction of the outflow. The mass of the UV heated gas exceeds the mass contained in the entrained outflow in the inner ~3000 AU and is therefore at least as important on small scales. Appendix A is available in electronic form at http://www.aanda.orgThe CHAMP+ maps (data cubes) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/576/A109

In Vitro Model for Predicting the Protective Effect of Ultraviolet-Blocking Contact Lens in Human Corneal Epithelial Cells.

PubMed

Abengózar-Vela, Antonio; Arroyo, Cristina; Reinoso, Roberto; Enríquez-de-Salamanca, Amalia; Corell, Alfredo; González-García, María Jesús

2015-01-01

To develop an in vitro method to determine the protective effect of UV-blocking contact lenses (CLs) in human corneal epithelial (HCE) cells exposed to UV-B radiation. SV-40-transformed HCE cells were covered with non-UV-blocking CL, UV-blocking CL or not covered, and exposed to UV-B radiation. As control, HCE cells were covered with both types of CLs or not covered, but not exposed to UV-B radiation. Cell viability at 24, 48 and 72 h, after UV-B exposure and removing CLs, was determined by alamarBlue(®) assay. Percentage of live, dead and apoptotic cells was also assessed by flow cytometry after 24 h of UV-B exposure. Intracellular reactive oxygen species (ROS) production after 1 h of exposure was assessed using the dye H(2)DCF-DA. Cell viability significantly decreased, apoptotic cells and intracellular ROS production significantly increased when UVB-exposed cells were covered with non-UV-blocking CL or not covered compared to non-irradiated cells. When cells were covered with UV-blocking CL, cell viability significantly increased and apoptotic cells and intracellular ROS production did not increase compared to exposed cells. UV-B radiation induces cell death by apoptosis, increases ROS production and decreases viable cells. UV-blocking CL is able to avoid these effects increasing cell viability and protecting HCE cells from apoptosis and ROS production induced by UV-B radiation. This in vitro model is an alternative to in vivo methods to determine the protective effect of UV-blocking ophthalmic biomaterials because it is a quicker, cheaper and reliable model that avoids the use of animals.

The effects of UV radiation during the vegetative period on antioxidant compounds and postharvest quality of broccoli (Brassica oleracea L.).

PubMed

Topcu, Yasin; Dogan, Adem; Kasimoglu, Zehra; Sahin-Nadeem, Hilal; Polat, Ersin; Erkan, Mustafa

2015-08-01

In this study, the effects of supplementary UV radiation during the vegetative period on antioxidant compounds, antioxidant activity and postharvest quality of broccoli heads during long term storage was studied. The broccolis were grown under three different doses of supplementary UV radiation (2.2, 8.8 and 16.4 kJ/m(2)/day) in a soilless system in a glasshouse. Harvested broccoli heads were stored at 0 °C in modified atmosphere packaging for 60 days. The supplementary UV radiation (280-315 nm) during the vegetative period significantly decreased total carotenoid, the chlorophyll a and chlorophyll b content but increased the ascorbic acid, total phenolic and flavonoid contents of broccolis. All supplementary UV treatments slightly reduced the antioxidant activity of the broccolis, however, no remarkable change was observed between 2.2 and 8.8 kJ/m(2) radiation levels. The sinigrin and glucotropaeolin contents of the broccolis were substantially increased by UV treatments. The prolonged storage period resulted in decreased ascorbic acid, total phenolic and flavonoid contents, as well as antioxidant activity. Discoloration of the heads, due to decreased chlorophyll and carotenoid contents, was also observed with prolonged storage duration. Glucosinolates levels showed an increasing tendency till the 45th day of storage, and then their levels started to decline. The weight loss of broccoli heads during storage progressively increased with storage time in all treatments. Total soluble solids, solids content and titratable acidity decreased continuously during storage. Titratable acidity was not affected by UV radiation doses during the storage time whereas soluble solids and solids content (dry matter) were significantly affected by UV doses. Supplementary UV radiation increased the lightness (L*) and chroma (C*) values of the broccoli heads. Pre-harvest UV radiation during vegetative period seems to be a promising tool for increasing the beneficial health components of broccolis. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

The potential for optical beam shaping of UV laser sources for mass scale quarantine disinfection applications

NASA Astrophysics Data System (ADS)

Lizotte, Todd

2010-08-01

Recent events concerning H1N1 "swine flu", have demonstrated to the world the significant potential of rapid increases in death and illness among all age groups and even among the healthy population [1] when a highly infectious influenza virus is introduced. In terms of mass casualties due to a pandemic, preparedness and response planning must be done. One course of action to prevent a pandemic outbreak or reduce the impact of a bioterrorist event is the use of isolation or quarantine facilities. The first level of isolation or quarantine is within the personal residence of the person exposed or infected. In the case where, the specific virus is extremely contagious and its onset of symptoms is rapid and severe, there will be a need for the deployment and setup of larger self contained quarantine facilities. Such facilities are used to house infectious individuals to minimize the exposure of susceptible individuals to contagious individuals, especially when specialized care or treatment is required and during the viral shedding period (5 to 7 days). These types of facilities require non-shared air conditioning, heating and ventilating systems where 100% of air is vented to the outside through a series of disinfection systems and staged filters. Although chemical disinfection is possible, there is a desire to incorporate intense UV radiation as a means to deactivate and disinfect airborne virus within hospital settings and isolated mass scale quarantine facilities. UV radiation is also being considered for disinfection of contaminated surfaces, such as table tops, walls and floors in hospitals and temporary quarantine facilities. In such applications the use of UV bulb technology can create many problems, for instance bulb technology requires numerous bulbs to treat a large volume of air, generates significant heat, uses significant power and does not produce large fluxes of UV light efficiently. This paper provides several methods of creating quarantine level disinfection systems using high intensity UV laser sources instead of UV bulb techniques by using laser beam shaping optics in conjunction with traditional optical laser beam delivery techniques.

Satellite estimation of surface spectral ultraviolet irradiance using OMI data in East Asia

NASA Astrophysics Data System (ADS)

Lee, H.; Kim, J.; Jeong, U.

2017-12-01

Due to a strong influence to the human health and ecosystem environment, continuous monitoring of the surface ultraviolet (UV) irradiance is important nowadays. The amount of UVA (320-400 nm) and UVB (290-320 nm) radiation at the Earth surface depends on the extent of Rayleigh scattering by atmospheric gas molecules, the radiative absorption by ozone, radiative scattering by clouds, and both absorption and scattering by airborne aerosols. Thus advanced consideration of these factors is the essential part to establish the process of UV irradiance estimation. Also UV index (UVI) is a simple parameter to show the strength of surface UV irradiance, therefore UVI has been widely utilized for the purpose of UV monitoring. In this study, we estimate surface UV irradiance at East Asia using realistic input based on OMI Total Ozone and reflectivity, and then validate this estimated comparing to UV irradiance from World Ozone and Ultraviolet Radiation Data Centre (WOUDC) data. In this work, we also try to develop our own retrieval algorithm for better estimation of surface irradiance. We use the Vector Linearized Discrete Ordinate Radiative Transfer (VLIDORT) model version 2.6 for our UV irradiance calculation. The input to the VLIDORT radiative transfer calculations are the total ozone column (TOMS V7 climatology), the surface albedo (Herman and Celarier, 1997) and the cloud optical depth. Based on these, the UV irradiance is calculated based on look-up table (LUT) approach. To correct absorbing aerosol, UV irradiance algorithm added climatological aerosol information (Arola et al., 2009). The further study, we analyze the comprehensive uncertainty analysis based on LUT and all input parameters.

Moderate salt treatment alleviates ultraviolet-B radiation caused impairment in poplar plants

NASA Astrophysics Data System (ADS)

Ma, Xuan; Ou, Yong-Bin; Gao, Yong-Feng; Lutts, Stanley; Li, Tao-Tao; Wang, Yang; Chen, Yong-Fu; Sun, Yu-Fang; Yao, Yin-An

2016-09-01

The effects of moderate salinity on the responses of woody plants to UV-B radiation were investigated using two Populus species (Populus alba and Populus russkii). Under UV-B radiation, moderate salinity reduced the oxidation pressure in both species, as indicated by lower levels of cellular H2O2 and membrane peroxidation, and weakened the inhibition of photochemical efficiency expressed by O-J-I-P changes. UV-B-induced DNA lesions in chloroplast and nucleus were alleviated by salinity, which could be explained by the higher expression levels of DNA repair system genes under UV-B&salt condition, such as the PHR, DDB2, and MutSα genes. The salt-induced increase in organic osmolytes proline and glycine betaine, afforded more efficient protection against UV-B radiation. Therefore moderate salinity induced cross-tolerance to UV-B stress in poplar plants. It is thus suggested that woody plants growing in moderate salted condition would be less affected by enhanced UV-B radiation than plants growing in the absence of salt. Our results also showed that UV-B signal genes in poplar plants PaCOP1, PaSTO and PaSTH2 were quickly responding to UV-B radiation, but not to salt. The transcripts of PaHY5 and its downstream pathway genes (PaCHS1, PaCHS4, PaFLS1 and PaFLS2) were differently up-regulated by these treatments, but the flavonoid compounds were not involved in the cross-tolerance since their concentration increased to the same extent in both UV-B and combined stresses.

Ultraviolet radiation-blocking characteristics of contact lenses: relevance to eye protection for psoralen-sensitised patients.

PubMed

Anstey, A; Taylor, D; Chalmers, I; Ansari, E

1999-10-01

Nine brands of contact lens marketed as "UV protective" were tested for ultraviolet (UV) transmission in order to assess potential suitability for psoralen-sensitised patients. UV-transmission characteristics of hydrated lenses was tested with a Bentham monochromator spectro-radiometer system. All lenses showed minimal transmission loss in the visible band. The performance of the nine lenses was uniform for ultraviolet B radiation with negligible transmission, but showed variation in transmission for ultraviolet A radiation. None of the lenses complied with UV-transmission criteria used previously to assess UV-blocking spectacles. Only two lenses had UV-blocking characteristics which came close to the arbitrary criteria used. The performance of ordinary soft and hard lenses was very similar, with negligible blocking of UV radiation. None of the nine contact lenses marketed as "UV protective" excluded sufficient UVA to comply with criteria in current use to assess UV protection in spectacles for psoralen-sensitised patients. However, the improved UV-blocking characteristics of contact lenses identified in this paper compared to previous studies suggests that such a contact lens will soon become available. Meanwhile, contact lens-wearing systemically sensitised PUVA patients should continue to wear approved spectacles for eye protection whilst photosensitised with psoralen.

Lipoxin A4 inhibits UV radiation-induced skin inflammation and oxidative stress in mice.

PubMed

Martinez, R M; Fattori, V; Saito, P; Melo, C B P; Borghi, S M; Pinto, I C; Bussmann, A J C; Baracat, M M; Georgetti, S R; Verri, W A; Casagrande, R

2018-04-27

Lipoxin A4 (LXA 4 ) is a metabolic product of arachidonic acid. Despite potent anti-inflammatory and pro-resolution activities, it remains to be determined if LXA 4 has effect on ultraviolet (UV) radiation-induced skin inflammation. To investigate the effects of systemic administration with LXA 4 on UV radiation-induced inflammation and oxidative damage in the skin of mice. Varied parameters of inflammation and oxidative stress in the skin of mice were evaluated after UV radiation (4.14 J/cm 2 ). Pretreatment with LXA 4 significantly inhibited UV radiation-induced skin edema and myeloperoxidase activity. LXA 4 efficacy was enhanced by increasing the time of pre-treatment to up to 72 h. LXA 4 reduced UV radiation-induced skin edema, neutrophil recruitment (myeloperoxidase activity and LysM-eGFP + cells), MMP-9 activity, deposition of collagen fibers, epidermal thickness, sunburn cell counts, and production of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6 and IL-33). Depending on the time point, LXA 4 increased the levels of anti-inflammatory cytokines (TGF-β and IL-10). LXA 4 significantly attenuated UV radiation-induced oxidative damage returning the oxidative status to baseline levels in parameters such as ferric reducing ability, scavenging of free radicals, GSH levels, catalase activity and superoxide anion production. LXA 4 also reduced UV radiation-induced gp91 phox [nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 2 (NOX2) subunit] mRNA expression and enhanced nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream target enzyme nicotinamide adenine dinucleotide (phosphate) quinone oxidoreductase (Nqo1) mRNA expression. LXA 4 inhibited UV radiation-induced skin inflammation by diminishing pro-inflammatory cytokine production and oxidative stress as well as inducing anti-inflammatory cytokines and Nrf2. Copyright © 2018. Published by Elsevier B.V.

INDICATORS OF UV EXPOSURE IN CORALS: RELEVANCE TO GLOBAL CLIMATE CHANGE AND CORAL BLEACHING

EPA Science Inventory

Increased exposure to solar UV radiation and elevated water temperatures are believed to play a role in the bleaching of corals. To provide additional tools for evaluating the role of UV radiation, we have examined UV-specific effects in coral and have characterized factors that ...

AlGaN UV LED and Photodiodes Radiation Hardness and Space Qualifications and Their Applications in Space Science and High Energy Density Physics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, K. X.

2011-05-31

This presentation provides an overview of robust, radiation hard AlGaN optoelectronic devices and their applications in space exploration & high energy density physics. Particularly, deep UV LED and deep UV photodiodes are discussed with regard to their applications, radiation hardness and space qualification. AC charge management of UV LED satellite payload instruments, which were to be launched in late 2012, is covered.

Responses of photosynthetic properties and chloroplast ultrastructure of Bryum argenteum from a desert biological soil crust to elevated ultraviolet-B radiation.

PubMed

Hui, Rong; Li, Xinrong; Chen, Cuiyun; Zhao, Xin; Jia, Rongliang; Liu, Lichao; Wei, Yongping

2013-04-01

Our understanding of plant responses to enhanced ultraviolet-B (UV-B) radiation has improved over recent decades. However, research on cryptogams is scarce and it remains controversial whether UV-B radiation causes changes in physiology related to photosynthesis. To investigate the effects of supplementary UV-B radiation on photosynthesis and chloroplast ultrastructure in Bryum argenteum Hedw., specimens were cultured for 10 days under four UV-B treatments (2.75, 3.08, 3.25 and 3.41 W m(-2) ), simulating depletion of 0% (control), 6%, 9% and 12% of stratospheric ozone at the latitude of Shapotou, a temperate desert area of northwest China. Analyses showed malondialdehyde content significantly increased, whereas chlorophyll (Chl) fluorescence parameters and Chl contents decreased with increased UV-B intensity. These results corresponded with changes in thylakoid protein complexes and chloroplast ultrastructure. Overall, enhanced UV-B radiation leads to significant decreases in photosynthetic function and serious destruction of the chloroplast ultrastructure of B. argenteum. The degree of negative influences increased with the intensity of UV-B radiation. These results may not only provide a potential mechanism for supplemental UV-B effects on photosynthesis of moss crust, but also establish a theoretical basis for further studies of adaptation and response mechanisms of desert ecosystems under future ozone depletion. Copyright © Physiologia Plantarum 2012.

Radiative decays of massive relic particles and the submillimeter background

NASA Technical Reports Server (NTRS)

Field, George B.; Walker, Terry P.

1989-01-01

The interaction of the decay photons of an unstable relic particle species with the microwave background radiation is considered. The radiative decays of these particles delay recombination and serve as an energy source for the resultant plasma. Nonrelativistic Compton scattering by these electrons couples the decay photons to the microwave background, producing submillimeter distortions. If the decay products close the universe, they must decay with a radiative branching ratio larger than 2.5 x 10 to the -5th in order to produce recently observed excess submillimeter background radiation. To be consistent with measurements of the UV background, their mass m is much greater than 114 keV and their decay redshift z is much greater than 5200.

UV exposure in cars.

PubMed

Moehrle, Matthias; Soballa, Martin; Korn, Manfred

2003-08-01

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

The Janus face of iron on anoxic worlds: iron oxides are both protective and destructive to life on the early Earth and present-day Mars.

PubMed

Wadsworth, Jennifer; Cockell, Charles S

2017-05-01

The surface of the early Earth was probably subjected to a higher flux of ultraviolet (UV) radiation than today. UV radiation is known to severely damage DNA and other key molecules of life. Using a liquid culture and a rock analogue system, we investigated the interplay of protective and deleterious effects of iron oxides under UV radiation on the viability of the model organism, Bacillus subtilis. In the presence of hydrogen peroxide, there exists a fine balance between iron oxide's protective effects against this radiation and its deleterious effects caused by Photo-Fenton reactions. The maximum damage was caused by a concentration of hematite of ∼1 mg/mL. Concentrations above this confer increasing protection by physical blockage of the UV radiation, concentrations below this cause less effective UV radiation blockage, but also a correspondingly less effective Photo-Fenton reaction, providing an overall advantage. These results show that on anoxic worlds, surface habitability under a high UV flux leaves life precariously poised between the beneficial and deleterious effects of iron oxides. These results have relevance to the Archean Earth, but also the habitability of the Martian surface, where high levels of UV radiation in combination with iron oxides and hydrogen peroxide can be found. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Effects of UV-B radiation on photosynthesis activity of Wolffia arrhiza as probed by chlorophyll fluorescence transients

NASA Astrophysics Data System (ADS)

Wang, Gaohong; Hao, Zongjie; Anken, Ralf H.; Lu, Jinying; Liu, Yongding

2010-04-01

The higher plant Wolffia arrhiza is regarded to be well suited concerning the provision of photosynthetic products in the cycle of matter of a Controlled Ecological Life Support System (CELSS) to be established in the context of extraterrestrial, human-based colonization and long-term space flight. Since UV radiation is one major extraterrestrial environmental stress for growth of any plant, effects of UV-B radiation on W. arrhiza were assessed in the present study. We found that UV-B radiation significantly inhibited photosynthetic CO2 assimilation activity, and the contents of chlorophyll a, chlorophyll b (Chl a, Chl b) and carotenoids considerably decreased when plants were exposed to UV-B radiation for 12 h. High UV-B radiation also declined the quantum yield of primary photochemistry (φpo), the quantum yield for electron transport (φEo) and the efficiency per trapped excitation (Ψo) in W. arrhiza simultaneously, while the amount of active PSII reaction centers per excited cross section (RC/CS) and the total number of active reaction centers per absorption (RC/ABS) had comparative changes. These results indicate that the effects of UV-B radiation on photosynthesis of W. arrhiza is due to an inhibition of the electron transport and via inactivation of reaction centers, but the inhibition may take place at more than one site in the photosynthetic apparatus.

Measurements of UV-A radiation and hazard limits from some types of outdoor lamps

NASA Astrophysics Data System (ADS)

El-Moghazy, Essam; Abd-Elmageed, Alaa-Eldin; Reda, Sameh

2015-05-01

Illumination using artificial light sources is common in these days. Many manufactures are paying for the design of lamps depending on high efficacy and low UV hazards. This research is focusing on the most useable lamps in the Egyptian markets; High Pressure Mercury (HPM), Metal Halide (MH), and High Pressure Sodium (HPS). A set up for relative spectral power distribution based on single monochromator and UVA silicon detector for absolute irradiance measurements are used. The absolute irradiance in (W/m2) in UVA region of the lamps and their accompanied standard uncertainty are evaluated.

Ultraviolet photosensitivity of sulfur-doped micro- and nano-crystalline diamond

DOE PAGES

Mendoza, Frank; Makarov, Vladimir; Hidalgo, Arturo; ...

2011-06-06

The room-temperature photosensitivity of sulfur-doped micro- (MCD), submicro- (SMCD) and nano- (NCD) crystalline diamond films synthesized by hot-filament chemical vapor deposition was studied. The structure and composition of these diamond materials were characterized by Raman spectroscopy, scanning electron microscopy and X-ray diffraction. The UV sensitivity and response time were studied for the three types of diamond materials using a steady state broad UV excitation source and two pulsed UV laser radiations. It was found that they have high sensitivity in the UV region, as high as 10 9 sec -1mV -1 range, linear response in a broad spectral range belowmore » 320 nm, photocurrents around ~10 -5 A, and short response time better than 100 ns, which is independent of fluency intensity. A phenomenological model was applied to help understand the role of defects and dopant concentration on the materials’ photosensitivity.« less

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

PubMed

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 ozone depletion could delay ozone recovery by several years, and this topic remains an area of intense research interest. Future changes in greenhouse gases will affect the future evolution of ozone through chemical, radiative, and dynamic processes In this highly coupled system, an evaluation of the relative importance of these processes is difficult: studies are ongoing. A reliable assessment of these effects on total column ozone is limited by uncertainties in lower stratospheric response to these changes. At several sites, changes in UV differ from those expected from ozone changes alone, possibly as a result of long-term changes in aerosols, snow cover, or clouds. This indicates a possible interaction between climate change and UV radiation. Cloud reflectance measured by satellite has shown a long-term increase at some locations, especially in the Antarctic region, but also in Central Europe, which would tend to reduce the UV radiation. Even with the expected decreases in atmospheric chlorine, it will be several years before the beginning of an ozone recovery can be unambiguously identified at individual locations. Because UV-B is more variable than ozone, any identification of its recovery would be further delayed.

Ultraviolet radiation changes

NASA Technical Reports Server (NTRS)

Mckenzie, Richard L.; Frederick, John E.; Ilyas, Mohammad; Filyushkin, V.; Wahner, Andreas; Stamnes, K.; Muthusubramanian, P.; Blumthaler, M.; Roy, Colin E.; Madronich, Sasha

1991-01-01

A major consequence of ozone depletion is an increase in solar ultraviolet (UV) radiation received at the Earth's surface. This chapter discusses advances that were made since the previous assessment (World Meteorological Organization (WMO)) to our understanding of UV radiation. The impacts of these changes in UV on the biosphere are not included, because they are discussed in the effects assessment.

ULTRAVIOLET RADIATION IN NORTH AMERICAN LAKES: ATTENUATION ESTIMATES FROM DOC MEASUREMENTS AND IMPLICATIONS FOR PLANKTON COMMUNITIES

EPA Science Inventory

Climate warming in North America is likely to be accompanied by changes in other environmental stresses such as UV-B radiation. We apply an empirical model to available DOC (dissolved organic C) data to estimate the depths to which 1% of surface UV-B and UV-A radiation penetrate ...

Impacts of diurnal variation of ultraviolet-B and photosynthetically active radiation on phycobiliproteins of the hot-spring cyanobacterium Nostoc sp. strain HKAR-2.

PubMed

Kannaujiya, Vinod K; Sinha, Rajeshwar P

2017-01-01

The effects of diurnal variation of photosynthetically active radiation (PAR; 400-700 nm) and ultraviolet-B (UV-B; 280-315 nm) radiation on phycobiliproteins (PBPs) and photosynthetic pigments (PP) have been studied in the hot-spring cyanobacterium Nostoc sp. strain HKAR-2. The variations in PBPs and PP were monitored by alternating light and dark under PAR, UV-B, and PAR + UV-B radiations over a period of 25 h. There was a decline in the amount of Chl a and PBPs during light periods of UV-B and PAR + UV-B and an increase during dark periods showing a circadian rhythm by destruction and resynthesis of pigment-protein complex. However, a marked induction in carotenoids was recorded during light periods of the same radiations. Moreover, the ratio of Chl a/PE and Chl a/PC was increased in dark periods showing the resynthesis of bleached Chl a. The wavelength shift in emission fluorescence of PBPs toward shorter wavelengths further indicated the bleaching and destruction of PBPs during light periods. Oxidative damage upon exposure to PAR, UV-B, and PAR + UV-B was alleviated by induction of antioxidative enzymes such as superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX). The studied cyanobacterium exhibits a significant increase in the activities of SOD, CAT, and APX upon exposure to UV-B and PAR + UV-B radiations. The results indicate that pigment-protein composition of Nostoc sp. stain HKAR-2 was significantly altered during diurnal variation of light/radiation, which might play an important role in optimization for their productivity in a particular cyanobacterium.

Growth of a mat-forming photograph in the presence of UV radiation

NASA Technical Reports Server (NTRS)

Pierson, Beverly K.; Ruff, A. L.

1989-01-01

Knowledge of the survival and growth of microorganisms in the presence of ultraviolet radiation is important for understanding the potential for life to exist in environments exposed to high fluxes of UV radiation. The growth of a mat-forming phototrophic prokaryote, Chloroflexus aurantiacus, was examined in the presence of continuous high UV irradiation under otherwise optimal growth conditions. Evidence was sought for an intrinsic ability to grow in the presence of UV radiation in a carefully chosen organism known to be unusually resistant to UV radiation, of ancient lineage among the phototrophs, to resemble ancient microfossils from the Precambrian, and to be a mat-former. It was assumed that even a high intrinsic UV resistance would be inadequate for survival and growth in the presence of very high UV fluxes, and iron (Fe3+) was selected as a common, abundant UV-absorbing substance that might protest microorganisms growing in or under iron-bearing sediments. The effectiveness of Fe(3+) was tested as a UV protective agent at low concentrations in thin layers. It was concluded that intrinsic UV resistance in some organisms may account for growth, not just survival, of these organisms when exposed to high UV fluxes under otherwise optimal growth conditions in an anoxic environment. It was also concluded that Fe(3+) bearing sediments of 1 mm or less in thickness may provide an adequate shield against high UV fluxes permitting the growth of microorganisms just below their surface. As long as growth conditions were met, then the evolution and development of microorganisms would not be hampered by high UV fluxes impinging upon the surface of iron-bearing sediments.

An immunohistochemical panel to assess ultraviolet radiation-associated oxidative skin injury.

PubMed

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

2014-05-01

Ultraviolet (UV) radiation results in a significant loss in years of healthy life, approximately 1.5 million disability-adjusted life years (DALYs), 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, we demonstrate that UV radiation-induced oxidative skin injury can be evaluated by an immunohistochemical panel that stains 8-hydroxydeoxyguanosine (8-OH-dG) to assess DNA adducts, 4-hydroxy-2-nonenal (HNE) to assess lipid peroxidation, and advanced glycation end products (AGEs) to assess protein damage. We believe this panel contains the necessary cellular biomarkers to evaluate topical agents, such as sunscreens and anti-oxidants that are designed to prevent oxidative skin damage and may reduce UV-associated skin aging, carcinogenesis, and inflammatory skin diseases. We envision that this panel will become an important tool for researchers developing topical agents to protect against UV radiation and other oxidants and ultimately lead to reductions in lost years of healthy life, DALYs, and annual deaths associated with UV radiation.

Time profile of cosmic radiation exposure during the EXPOSE-E mission: the R3DE instrument.

PubMed

Dachev, Tsvetan; Horneck, Gerda; Häder, Donat-Peter; Schuster, Martin; Richter, Peter; Lebert, Michael; Demets, Rene

2012-05-01

The aim of this paper is to present the time profile of cosmic radiation exposure obtained by the Radiation Risk Radiometer-Dosimeter during the EXPOSE-E mission in the European Technology Exposure Facility on the International Space Station's Columbus module. Another aim is to make the obtained results available to other EXPOSE-E teams for use in their data analysis. Radiation Risk Radiometer-Dosimeter is a low-mass and small-dimension automatic device that measures solar radiation in four channels and cosmic ionizing radiation as well. The main results of the present study include the following: (1) three different radiation sources were detected and quantified-galactic cosmic rays (GCR), energetic protons from the South Atlantic Anomaly (SAA) region of the inner radiation belt, and energetic electrons from the outer radiation belt (ORB); (2) the highest daily averaged absorbed dose rate of 426 μGy d(-1) came from SAA protons; (3) GCR delivered a much smaller daily absorbed dose rate of 91.1 μGy d(-1), and the ORB source delivered only 8.6 μGy d(-1). The analysis of the UV and temperature data is a subject of another article (Schuster et al., 2012 ).

Response of Two Legumes to Two Ultraviolet-B Radiation Regimes

NASA Technical Reports Server (NTRS)

Levy, Daniel L.; Skiles, J. W.

2000-01-01

Depletion of the stratospheric ozone layer has been directly linked to increased levels of UV radiation at the earth's surface. The purpose of this study was to evaluate the responses of soybean (Glycine max) and alfalfa (Medicago sativa) to increased UV-B radiation (280-320 nm). Soybean and alfalfa were grown successively in a growth chamber that provided UV-B intensities 45% above nominal summer field levels. Mylar-D (UVB opaque) and mono-acetate (UV-B transparent) films were used to establish the two UV-B treatments. Soybean grown under increased UV showed 21% smaller internodal lengths and higher concentrations of UV-B absorbing pigments (i.e. flavonoids) compared to plants grown under no UV. Significant results for alfalfa included 22% greater leaf flavonoid concentration under increased UV, 14% greater leaf chlorophyll concentration under no UV, and 32% greater above-ground biomass with no UV. These leguminous species possess mechanisms that protect against UV-B damage as indicated by increases in foliar concentrations of UV-B absorbing compounds. Alfalfa appears to be more sensitive to UV-B damage than soybean. Remote sensing of chlorophyll fluorescence may offer a means of monitoring UV-induced plant stress and damage.

Infrared emission in Seyfert 2 galaxies - Reprocessed radiation from a dusty torus?

NASA Technical Reports Server (NTRS)

Storchi-Bergmann, Thaisa; Mulchaey, John S.; Wilson, Andrew S.

1992-01-01

New and existing data for a sample of nine Seyfert 2 galaxies with known 'ionization cones' are combined in order to test whether collimation results from shadowing of radiation from a small isotropic nuclear source by a thick dusty torus. The number of ionizing photons emitted by the compact nucleus is calculated from the emission-line ratios measured for gas within the cones. On the assumption that this compact nuclear source radiates isotropically, the optical-UV power incident on the torus, which is expected to be reradiated in the IR, is determined. It is found that the observed IRAS luminosities are consistent with the torus model in eight of the nine objects with sufficient data to perform the calculation. It is concluded that the data are generally consistent with collimation and reradiation by a dusty torus.

Radiation studies of optical and electronic components used in astronomical satellite studies

NASA Technical Reports Server (NTRS)

Becher, J.; Kernell, R. L.

1981-01-01

The synchronous orbit of the IUE carries the satellite through Earth's outer electron belt. A 40 mCi Sr90 source was used to simulate these electrons. A 5 mCi source of Co60 was used to simulate bremmstrahlung. A 10 MeV electron Linac and a 1.7 MeV electron Van de Graaf wer used to investigate the energy dependence of radiation effects and to perform radiations at a high flux rate. A 100 MeV proton cyclotron was used to simulate cosmic rays. Results are presented for three instrument systems of the IUE and measurements for specific components are reported. The three instrument systems were the ultraviolet converter, the fine error sensor (FES), and the SEC vidicon camera tube. The components were optical glasses, electronic components, silicon photodiodes, and UV window materials.

Determination of minimal erythema dose and anomalous reactions to UVA radiation by skin phototype.

PubMed

Pérez Ferriols, A; Aguilera, J; Aguilera, P; de Argila, D; Barnadas, M A; de Cabo, X; Carrrascosa, J M; de Gálvez Aranda, M V; Gardeazábal, J; Giménez-Arnau, A; Lecha, M; Lorente, J; Martínez-Lozano, J A; Rodríguez Granados, M T; Sola, Y; Utrillas, M P

2014-10-01

Phototesting is a technique that assesses the skin's sensitivity to UV radiation by determining the smallest dose of radiation capable of inducing erythema (minimal erythema dose [MED]) and anomalous responses to UV-A radiation. No phototesting protocol guidelines have been published to date. This was a multicenter prospective cohort study in which 232 healthy volunteers were recruited at 9 hospitals. Phototests were carried out with solar simulators or fluorescent broadband UV-B lamps. Each individual received a total of 5 or 6 incremental doses of erythemal radiation and 4 doses of UV-A radiation. The results were read at 24hours. At hospitals where solar simulators were used, the mean (SD) MED values were 23 (8), 28 (4), 35 (4), and 51 (6) mJ/cm(2) for skin phototypes i to iv, respectively. At hospitals where broadband UV-B lamps were used, these values were 28 (5), 32 (3), and 34 (5) mJ/cm(2) for phototypes ii to iv, respectively. MED values lower than 7, 19, 27, and 38 mJ/cm(2) obtained with solar simulators were considered to indicate a pathologic response for phototypes I to IV, respectively. MED values lower than 18, 24, and 24mJ/cm(2) obtained with broadband UV-B lamps were considered to indicate a pathologic response for phototypes ii to iv, respectively. No anomalous responses were observed at UV-A radiation doses of up to 20J/cm(2). Results were homogeneous across centers, making it possible to standardize diagnostic phototesting for the various skin phototypes and establish threshold doses that define anomalous responses to UV radiation. Copyright © 2014 Elsevier España, S.L.U. y AEDV. All rights reserved.

Probing Jupiter's Radiation Environment with Juno-UVS

NASA Astrophysics Data System (ADS)

Kammer, J.; Gladstone, R.; Greathouse, T. K.; Hue, V.; Versteeg, M. H.; Davis, M. W.; Santos-Costa, D.; Becker, H. N.; Bolton, S. J.; Connerney, J. E. P.; Levin, S.

2017-12-01

While primarily designed to observe photon emission from the Jovian aurora, Juno's Ultraviolet Spectrograph (Juno-UVS) has also measured background count rates associated with penetrating high-energy radiation. These background counts are distinguishable from photon events, as they are generally spread evenly across the entire array of the Juno-UVS detector, and as the spacecraft spins, they set a baseline count rate higher than the sky background rate. During eight perijove passes, this background radiation signature has varied significantly on both short (spin-modulated) timescales, as well as longer timescales ( minutes to hours). We present comparisons of the Juno-UVS data across each of the eight perijove passes, with a focus on the count rate that can be clearly attributed to radiation effects rather than photon events. Once calibrated to determine the relationship between count rate and penetrating high-energy radiation (e.g., using existing GEANT models), these in situ measurements by Juno-UVS will provide additional constraints to radiation belt models close to the planet.

Upregulated epidermal growth factor receptor expression following near-infrared irradiation simulating solar radiation in a three-dimensional reconstructed human corneal epithelial tissue culture model.

PubMed

Tanaka, Yohei; Nakayama, Jun

2016-01-01

Humans are increasingly exposed to near-infrared (NIR) radiation from both natural (eg, solar) and artificial (eg, electrical appliances) sources. Although the biological effects of sun and ultraviolet (UV) exposure have been extensively investigated, the biological effect of NIR radiation is still unclear. We previously reported that NIR as well as UV induces photoaging and standard UV-blocking materials, such as sunglasses, do not sufficiently block NIR. The objective of this study was to investigate changes in gene expression in three-dimensional reconstructed corneal epithelial tissue culture exposed to broad-spectrum NIR irradiation to simulate solar NIR radiation that reaches human tissues. DNA microarray and quantitative real-time polymerase chain reaction analysis were used to assess gene expression levels in a three-dimensional reconstructed corneal epithelial model composed of normal human corneal epithelial cells exposed to water-filtered broad-spectrum NIR irradiation with a contact cooling (20°C). The water-filter allowed 1,000-1,800 nm wavelengths and excluded 1,400-1,500 nm wavelengths. A DNA microarray with >62,000 different probes showed 25 and 150 genes that were up- or downregulated by at least fourfold and twofold, respectively, after NIR irradiation. In particular, epidermal growth factor receptor (EGFR) was upregulated by 19.4-fold relative to control cells. Quantitative real-time polymerase chain reaction analysis revealed that two variants of EGFR in human corneal epithelial tissue were also significantly upregulated after five rounds of 10 J/cm(2) irradiation (P<0.05). We found that NIR irradiation induced the upregulated expression of EGFR in human corneal cells. Since over half of the solar energy reaching the Earth is in the NIR region, which cannot be adequately blocked by eyewear and thus can induce eye damage with intensive or long-term exposure, protection from both UV and NIR radiation may prevent changes in gene expression and in turn eye damage.

Repair of cyclobutyl pyrimidine dimers in human skin: variability among normal humans in nucleotide excision and in photorepair.

PubMed

Sutherland, Betsy M; Hacham, Haim; Bennett, Paula; Sutherland, John C; Moran, Michael; Gange, R W

2002-06-01

Photoreactivation (PR) of cyclobutyl pyrimidine dimers (CPD) in human skin remains controversial. Recently Whitmore et al. (1) reported negative results of experiments using two photorepair light (PRL) sources on UV-irradiated skin of volunteers. However, their PRL sources induced substantial levels of dimers in skin, suggesting that the additional dimers formed could have obscured PR. We met a similar problem of dimer induction by a PRL source. We designed and validated a PRL source of sufficient intensity to catalyse PR, but that did not induce CPD, and used it to measure photorepair in human skin. Using a solar simulator filtered with three types of UV-filters, we found significant dimer formation in skin, quantified by number average length analysis using electrophoretic gels of isolated skin DNA. To prevent scattered UV from reaching the skin, we interposed shields between the filters and skin, and showed that the UV-filtered/shielded solar simulator system did not induce damage in isolated DNA or in human skin. We exposed skin of seven healthy human volunteers to 302 nm radiation, then to the improved PRL source (control skin areas were kept in the dark for measurement of excision repair). Using a high intensity PRL source that did not induce dimers in skin, we found that three of seven subjects carried out rapid photorepair of dimers; two carried out moderate or slow dimer photorepair, and three did not show detectable photorepair. Excision repair was similarly variable in these volunteers. Subjects with slower excision repair showed rapid photorepair, whereas those with rapid excision generally showed little or no photoreactivation.

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

NASA Astrophysics Data System (ADS)

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

2009-07-01

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

Sunlight Effects on Immune System: Is There Something Else in addition to UV-Induced Immunosuppression?

PubMed Central

Paz, M. L.; Leoni, J.

2016-01-01

Sunlight, composed of different types of radiation, including ultraviolet wavelengths, is an essential source of light and warmth for life on earth but has strong negative effects on human health, such as promoting the malignant transformation of skin cells and suppressing the ability of the human immune system to efficiently detect and attack malignant cells. UV-induced immunosuppression has been extensively studied since it was first described by Dr. Kripke and Dr. Fisher in the late 1970s. However, skin exposure to sunlight has not only this and other unfavorable effects, for example, mutagenesis and carcinogenesis, but also a positive one: the induction of Vitamin D synthesis, which performs several roles within the immune system in addition to favoring bone homeostasis. The impact of low levels of UV exposure on the immune system has not been fully reported yet, but it bears interesting differences with the suppressive effect of high levels of UV radiation, as shown by some recent studies. The aim of this article is to put some ideas in perspective and pose some questions within the field of photoimmunology based on established and new information, which may lead to new experimental approaches and, eventually, to a better understanding of the effects of sunlight on the human immune system. PMID:28070504

LEAF UV OPTICAL PROPERTIES OF 'RUMEX PATIENTIA' L. AND 'RUMEX OBTUSIFOLIUS L. IN REGARD TO A PROTECTIVE MECHANISM AGAINST SOLAR UV-B RADIATION INJURY

EPA Science Inventory

Effective UV attenuation in the outer leaf layers may represent an important protective mechanism against potentially damaging solar UV-B radiation. Epidermal optical properties for Rumex patientia and Rumex obtusifolius were examined on field collected and greenhouse grown plant...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Erickson III, David J.; Sulzberger, Barbara; Zepp, Richard G.

Climate change modulates the effects of solar UV radiation on biogeochemical cycles in terrestrial and aquatic ecosystems, particularly for carbon cycling, resulting in UV-mediated positive or negative feedbacks on climate. Possible positive feedbacks discussed in this assessment include: (i) enhanced UV-induced mineralisation of above ground litter due to aridification; (ii) enhanced UV-induced mineralisation of photoreactive dissolved organic matter (DOM) in aquatic ecosystems due to changes in continental runoff and ice melting; (iii) reduced efficiency of the biological pump due to UV-induced bleaching of coloured dissolved organic matter (CDOM) in stratified aquatic ecosystems, where CDOM protects phytoplankton from the damaging solarmore » UV-B radiation. Mineralisation of organic matter results in the production and release of CO 2, whereas the biological pump is the main biological process for CO 2 removal by aquatic ecosystems. This research also assesses the interactive effects of solar UV radiation and climate change on the biogeochemical cycling of aerosols and trace gases other than CO 2, as well as of chemical and biological contaminants. Lastly,, interacting effects of solar UV radiation and climate change on biogeochemical cycles are particularly pronounced at terrestrial-aquatic interfaces.« less

The solar UV environment and bacterial spore UV resistance: considerations for Earth-to-Mars transport by natural processes and human spaceflight.

PubMed

Nicholson, Wayne L; Schuerger, Andrew C; Setlow, Peter

2005-04-01

The environment in space and on planets such as Mars can be lethal to microorganisms because of the high vacuum and high solar radiation flux, in particular UV radiation, in such environments. Spores of various Bacillus species are among the organisms most resistant to the lethal effects of high vacuum and UV radiation, and as a consequence are of major concern for planetary contamination via unmanned spacecraft or even natural processes. This review focuses on the spores of various Bacillus species: (i) their mechanisms of UV resistance; (ii) their survival in unmanned spacecraft, space flight and simulated space flight and Martian conditions; (iii) the UV flux in space and on Mars; (iv) factors affecting spore survival in such high UV flux environments.

The effects of UV-B radiation intensity on biochemical parameters and active ingredients in flowers of Qi chrysanthemum and Huai chrysanthemum.

PubMed

Yao, Xiao-Qin; Chu, Jian-Zhou; He, Xue-Li; Si, Chao

2014-01-01

The article studied UV-B effects on biochemical parameters and active ingredients in flowers of Qi chrysanthemum and Huai chrysanthemum during the bud stage. The experiment included four UV-B radiation levels (CK, ambient UV-B; T1, T2 and T3 indicated a 5%, 10% and 15% increase in ambient UV-BBE, respectively) to determine the optimal UV-B radiation intensity in regulating active ingredients level in flowers of two chrysanthemum varieties. Flower dry weight of two cultivars was not affected by UV-B radiation under experimental conditions reported here. UV-B treatments significantly increased the rate of superoxide radical production, hydrogen peroxide (H2O2) (except for T1) and malondialdehyde concentration in flowers of Huai chrysanthemum and H2O2 concentration in flowers of Qi chrysanthemum. T2 and T3 treatments induced a significant increase in phenylalanine ammonia lyase enzyme (PAL) activity, anthocyanins, proline, ascorbic acid, chlorogenic acid and flavone content in flowers of two chrysanthemum varieties, and there were no significant differences in PAL activity, ascorbic acid, flavone and chlorogenic acid content between the two treatments. These results indicated that appropriate UV-B radiation intensity did not result in the decrease in flower yield, and could regulate PAL activity and increase active ingredients content in flowers of two chrysanthemum varieties. © 2014 The American Society of Photobiology.

Effect of lanthanum(III) on the production of ethylene and reactive oxygen species in soybean seedlings exposed to the enhanced ultraviolet-B radiation.

PubMed

Yang, Qing; Li, Yueli; Wang, Lihong; Zhou, Qing; Huang, Xiaohua

2014-06-01

The enhanced ultraviolet-B (UV-B) radiation caused by ozone depletion may exert deleterious effects on plants. Therefore, studies on the effect of UV-B radiation on plants, as well as studies on the methods for alleviating the deleterious effects by chemical control, are of great significance. In this study, after soybean (Glycine max) seedlings were exposed to UV-B radiation (10.2 and 13.8kJ m(-2)day(-1)) for 5 days and the followed 6 days of restoration, respectively, the effects of 20mg L(-1) lanthanum (III) [La(III)] on leaf phenotype, photosynthetic rate, and production of ethylene and reactive oxygen species (ROS) were investigated. The results indicated that the exposure to 10.2 and 13.8kJ m(-2)day(-1) UV-B radiation could cause injury to the leaf phenotype, and lead to the decrease in the content of chlorophyll and the net photosynthetic rate, and the increase in the contents of ROS, ethylene and 1-aminocyclopropanecarboxylic acid, and 1-aminocyclopropanecarboxylic acid synthase activity in soybean seedlings. Following the withdrawal of the enhanced UV-B radiation, the above mentioned parameters gradually recovered, and the recovery of soybean seedlings exposed to 10.2kJ m(-2)day(-1) UV-B radiation was faster than those in soybean seedlings exposed to 13.8kJ m(-2)day(-1) UV-B radiation. The leaf injury and the changes in the above indices that were induced by the enhanced UV-B radiation, especially at 10.2kJ m(-2)day(-1), were alleviated after the pretreatment of soybean seedlings with 20mg L(-1) La(III). The results of the correlation analysis demonstrated that the injury to the leaf phenotype and the decrease in the photosynthetic rate of soybean seedlings were correlated with the increase in the ROS content that was induced by ethylene in soybean seedlings. The pretreatment with 20mg L(-1) La(III) alleviated the injury caused by the enhanced UV-B radiation through the regulation of the ROS production. Copyright © 2014 Elsevier Inc. All rights reserved.

Effects of solar UV radiation and climate change on biogeochemical cycling: interactions and feedbacks.

PubMed

Zepp, R G; Erickson, D J; Paul, N D; Sulzberger, B

2011-02-01

Solar UV radiation, climate and other drivers of global change are undergoing significant changes and models forecast that these changes will continue for the remainder of this century. Here we assess the effects of solar UV radiation on biogeochemical cycles and the interactions of these effects with climate change, including feedbacks on climate. Such interactions occur in both terrestrial and aquatic ecosystems. While there is significant uncertainty in the quantification of these effects, they could accelerate the rate of atmospheric CO(2) increase and subsequent climate change beyond current predictions. The effects of predicted changes in climate and solar UV radiation on carbon cycling in terrestrial and aquatic ecosystems are expected to vary significantly between regions. The balance of positive and negative effects on terrestrial carbon cycling remains uncertain, but the interactions between UV radiation and climate change are likely to contribute to decreasing sink strength in many oceanic regions. Interactions between climate and solar UV radiation will affect cycling of elements other than carbon, and so will influence the concentration of greenhouse and ozone-depleting gases. For example, increases in oxygen-deficient regions of the ocean caused by climate change are projected to enhance the emissions of nitrous oxide, an important greenhouse and ozone-depleting gas. Future changes in UV-induced transformations of aquatic and terrestrial contaminants could have both beneficial and adverse effects. Taken in total, it is clear that the future changes in UV radiation coupled with human-caused global change will have large impacts on biogeochemical cycles at local, regional and global scales.

[Effects of silicon supply on rice growth and methane emission from paddy soil under elevated UV-B radiation].

PubMed

Meng, Yan; Lou, Yun-sheng; Wu, Lei; Cui, He-yang; Wang, Wei-qing

2015-01-01

A pot experiment was conducted to investigate the effects of silicon supply on rice growth and methane (CH4) emission in paddy field under elevated UV-B radiation. The experiment was designed with two UV-B radiation levels, i.e. ambient UV-B (ambient, A) and elevated UV-B radiation (elevated by 20%, E) ; with four silicon supply levels, i.e., Si0 (control, without silicon), Si2 (as sodium silicate, 100 kg SiO2 . hm-2), Si2 (as sodium silicate, 200 kg SiO2 hm-2) and Si3 (as slag fertilizer, 200 kg SiO2 . hm-2). The results indicated that, silicon supply obviously alleviated the depressive effect of elevated UV-B radiation on rice growth, and increased the tiller numbers, chlorophyll content, and shoot and root dry masses. Silicon supply promoted rice growth, which increased with the silicon supply level (sodium silicate). Slag fertilizer was better than*sodium silicate in promoting rice growth. CH4 flux and accumulated CH4emission were obviously increased by elevated UV-B radiation, but significantly decreased by silicon application. CH4 emission was reduced with increasing the silicon supply level. Under the same silicon supply level, slag fertilizer was better than sodium silicate in inhibiting CH4 flux and accumulated CH4 emission. This research suggested that fertilizing slag in rice production was helpful not only in utilizing industrial wastes, but also in significantly mitigating CH4 emissions in rice paddy under elevated UV-B radiation.

A novel research model for evaluating sunscreen protection in the UV-A1.

PubMed

Figueiredo, Sônia Aparecida; de Moraes, Dayane Cristina; Vilela, Fernanda Maria Pinto; de Faria, Amanda Natalina; Dos Santos, Marcelo Henrique; Fonseca, Maria José Vieira

2018-01-01

The use of a broad spectrum sunscreen is considered one of the main and most popular measures for preventing the damaging effects of ultraviolet radiation (UVR) on the skin. In this study we have developed a novel in vitro method to assess sunscreens efficacy to protect calcineurin enzyme activity, a skin cell marker. The photoprotective efficacy of sunscreen products was assessed by measuring the UV-A1 radiation-induced depletion of calcineurin (Cn) enzyme activity in primary neonatal human dermal fibroblast (HDFn) cell lysates. After exposure to 24J/cm 2 UV-A1 radiation, the sunscreens containing larger amounts of UV-A1 filters (brand B), the astaxanthin (UV-A1 absorber) and the Tinosorb® M (UV-A1 absorber) were capable of preventing loss of Cn activity when compared to the sunscreens formulations of brand A (low concentration of UV-A1 filters), with the Garcinia brasiliensis extract (UV-B absorber) and with the unprotected cell lysate and exposed to irradiation (Irradiated Control - IC). The Cn activity assay is a reproducible, accurate and selective technique for evaluating the effectiveness of sunscreens against the effects of UV-A1 radiation. The developed method showed that calcineurin activity have the potential to act as a biological indicator of UV-A1 radiation-induced damages in skin and the assay might be used to assess the efficacy of sunscreens agents and plant extracts prior to in vivo tests. Copyright © 2017 Elsevier B.V. All rights reserved.

Flares and habitability

NASA Astrophysics Data System (ADS)

Abrevaya, Ximena C.; Cortón, Eduardo; Mauas, Pablo J. D.

2012-07-01

At present, dwarf M stars are being considered as potential hosts for habitable planets. However, an important fraction of these stars are flare stars, which among other kind of radiation, emit large amounts of UV radiation during flares, and it is unknown how this events can affect life, since biological systems are particularly vulnerable to UV. In this work we evaluate a well known dMe star, EV Lacertae (GJ 873) as a potential host for the emergence and evolution of life, focusing on the effects of the UV emission associated with flare activity. Since UV-C is particularly harmful for living organisms, we studied the effect of UV-C radiation on halophile archaea cultures. The halophile archaea or haloarchaea are extremophile microorganisms, which inhabit in hypersaline environments and which show several mechanisms to cope with UV radiation since they are naturally exposed to intense solar UV radiation on Earth. To select the irradiance to be tested, we considered a moderate flare on this star. We obtained the mean value for the UV-C irradiance integrating the IUE spectrum in the impulsive phase, and considering a hypothetical planet in the center of the liquid water habitability zone. To select the irradiation times we took the most frequent duration of flares on this star which is from 9 to 27 minutes. Our results show that even after considerable UV damage, the haloarchaeal cells survive at the tested doses, showing that this kind of life could survive in a relatively hostile UV environment.

Leaf expansion and development of photosynthetic capacity and pigments in Liquidambar Styraciflua (Hamamelidaceae)-effects of UV-B radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dillenburg, L.R.; Sullivan, J.H.; Teramura, A.H.

1995-07-01

In order to perform their functions as photosynthetic organs, leaves must cope with excess heat and potentially damaging ultraviolet radiation. Possible increases in the UV-B portion of the solar spectrum may place an additional burden on leaves, and this could be particularly important for young expanding leaves with poorly developed UV-B defense mechanisms. We evaluated the effects of supplemental UV-B radiation on leaf expansion and the development of photosynthetic capacity and pigments in sweetgum (Liquidambar styraciflua L.) seedlings. Seedlings were grown in the field under either ambient or ambient plus 3 or 5.0 kJ of biologically effective supplemental UV-B radiation.more » Although final leaf size was unaffected, the rate of leaf elongation and accumulation of leaf area was slower in leaves exposed to the lower supplemental UV-B irradiance. In contrast, chlorophyll accumulation and the development of photosynthetic capacity was more rapid in plants exposed to the higher, compared to the lower supplemental UV-B irradiance. The accumulation of anthocyanins and other putative flavonoids or UV-absorbing compounds was scarcely affected by exposure to supplemental UV-B radiation. These results suggest that the UV-B portion of the solar spectrum may, in the absence of gross affects on biomass, exert subtle influences on leaf ontogeny and the development of photosynthetic pigments and capacity in sweetgum. 44 refs., 6 figs.« less

RENU 2 UV Measurements of Atomic Oxygen in the Cusp Region

NASA Astrophysics Data System (ADS)

Fritz, B.; Lessard, M.; Paxton, L. J.; Cook, T.; Lynch, K. A.; Clemmons, J. H.; Hecht, J. H.; Hysell, D. L.; Crowley, G.

2016-12-01

The RENU 2 NASA sounding rocket mission launched from the Andoya Space Center on 13 December, 2015 into the dayside cusp region. A UV Photometer (UV PMT) provided by the University of New Hampshire was oriented to look up along the local magnetic field line as the payload passed through a poleward moving auroral form (PMAF). The bandpass filter on the UV PMT isolated emissions of atomic oxygen at both 130.4 nm and 135.6 nm. The instrument measured a clear enhancement in the topside ionosphere as the payload descended through a region of soft electron precipitation. The RENU 2 UV PMT was flown uncalibrated but measured a clear signal with both a major overall structure as well as several smaller peaks of fine structure. An identical spare has been built and calibrated using a Paresce UV light source at UMass-Lowell to compare and correlate with the flight data. An approximation of the flight data luminosity from the spare instrument and other flight data from RENU 2 is used in a radiative transport model to infer structure of upwelling neutral atomic oxygen above the PMAF.

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

PubMed

Omairi, Tareq; Wainwright, Milton

2015-07-01

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

UV-B Induced Generation of Reactive Oxygen Species Promotes Formation of BFA-Induced Compartments in Cells of Arabidopsis Root Apices

PubMed Central

Yokawa, Ken; Kagenishi, Tomoko; Baluška, František

2016-01-01

UV-B radiation is an important part of the electromagnetic spectrum emitted by the sun. For much of the period of biological evolution organisms have been exposed to UV radiation, and have developed diverse mechanisms to cope with this potential stress factor. Roots are usually shielded from exposure to UV by the surrounding soil, but may nevertheless be exposed to high energy radiation on the soil surface. Due to their high sensitivity to UV-B radiation, plant roots need to respond rapidly in order to minimize exposure on the surface. In addition to root gravitropism, effective light perception by roots has recently been discovered to be essential for triggering negative root phototropism in Arabidopsis. However, it is not fully understood how UV-B affects root growth and phototropism. Here, we report that UV-B induces rapid generation of reactive oxygen species which in turn promotes the formation of BFA-induced compartments in the Arabidopsis root apex. During unilateral UV-B irradiation of roots changes in auxin concentration on the illuminated side have been recorded. In conclusion, UV-B-induced and ROS-mediated stimulation of vesicle recycling promotes root growth and induces negative phototropism. PMID:26793199

Inconstant sun: how solar evolution has affected cosmic and ultraviolet radiation exposure over the history of life on Earth.

PubMed

Karam, P Andrew

2003-03-01

Four billion years ago, sea-level UV exposure was more than 400 times as intense as today, the dose from solar cosmic rays was five times present levels, and galactic cosmic rays accounted for only about 10% their current contribution to sea-level radiation doses. Exposure to cosmic radiation accounts for about 10% of natural background radiation exposure today and includes dose from galactic cosmic rays and solar charged particles. There is little exposure to ionizing wavelengths of UV due to absorption by ozone. The sun has evolved significantly over its life; in the past there were higher levels of particulate radiation and lower UV emissions from the sun, and a stronger solar wind reduced radiation dose in the inner solar system from galactic cosmic rays. Finally, since the early atmosphere contained little to no oxygen, surface levels of UV radiation were far higher in the past.

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

PubMed

Singh, Jaswant; Singh, Rudra P

2014-01-01

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

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

PubMed Central

Singh, Jaswant; Singh, Rudra P.

2014-01-01

This study aimed to assess the impacts of ultraviolet-B (UV-B) radiation over a 28-day period on the levels of pigments of Umbilicaria aprina and Bryum argenteum growing in field. The depletion of stratospheric ozone is most prominent over Antarctica, which receives more UV-B radiation than most other parts of the planet. Although UV-B radiation adversely affects all flora, Antarctic plants are better equipped to survive the damaging effects of UV-B owing to defenses provided by UV-B absorbing compounds and other screening pigments. The UV-B radiations and daily average ozone values were measured by sun photometer and the photosynthetic pigments were analyzed by the standard spectrophotometric methods of exposed and unexposed selected plants. The daily average atmospheric ozone values were recorded from 5 January to 2 February 2008. The maximum daily average for ozone (310.7 Dobson Units (DU)) was recorded on 10 January 2008. On that day, average UV-B spectral irradiances were 0.016, 0.071, and 0.186 W m-2 at wavelengths of 305, 312, and 320 nm, respectively. The minimum daily average ozone value (278.6 DU) was recorded on 31 January 2008. On that day, average UV-B spectral irradiances were 0.018, 0.085, and 0.210 W m-2 at wavelengths of 305, 312, and 320 nm, respectively. Our results concludes that following prolonged UV-B exposure, total chlorophyll levels decreased gradually in both species, whereas levels of UV-B absorbing compounds, phenolics, and carotenoids gradually increased. PMID:24748743

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

1982-02-01

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

An ESR study of the UV degradation of FEP

NASA Technical Reports Server (NTRS)

George, G. A.; Hill, D. J. T.; Odonnell, J. H.; Pomery, P. J.; Rasoul, F.

1992-01-01

Spacecraft in low earth orbit are subjected to significant levels of high energy radiation, including ultraviolet (UV) and visible ultraviolet (VUV) wavelengths. The effects of UV radiation are enhanced over those at the surface of the earth, where the only incident wavelengths are greater than 290 nm. In low earth orbit the incident UV wavelengths extend below 290 nm into the VUV region, where the Lyman alpha-emissions of atomic hydrogen occur at 121 nm. In addition to electromagnetic radiation, in low earth orbit polymer materials may also be subjected to atomic oxygen particle radiation, which will result in direct oxidation of the polymer.

Total ozone column, aerosol optical depth and precipitable water effects on solar erythemal ultraviolet radiation recorded in Malta.

NASA Astrophysics Data System (ADS)

Bilbao, Julia; Román, Roberto; Yousif, Charles; Mateos, David; Miguel, Argimiro

2013-04-01

The Universities of Malta and Valladolid (Spain) developed a measurement campaign, which took place in the Institute for Energy Technology in Marsaxlokk (Southern Malta) between May and October 2012, and it was supported by the Spanish government through the Project titled "Measurement campaign about Solar Radiation, Ozone, and Aerosol in the Mediterranean area" (with reference CGL2010-12140-E). This campaign provided the first ground-based measurements in Malta of erythemal radiation and UV index, which indicate the effectiveness of the sun exposure to produce sunburn on human skin. A wide variety of instruments was involved in the campaign, providing a complete atmospheric characterization. Data of erythemal radiation and UV index (from UVB-1 pyranometer), total shortwave radiaton (global and diffuse components from CM-6B pyranometers), and total ozone column, aerosol optical thickness, and precitable water column (from a Microtops-II sunphotometer) were available in the campaign. Ground-based and satellite instruments were used in the analysis, and several intercomparisons were carried out to validate remote sensing data. OMI, GOME, GOME-2, and MODIS instruments, which provide data of ozone, aerosol load and optical properties, were used to this end. The effects on solar radiation, ultraviolet and total shortwave ranges, of total ozone column, aerosol optical thickness and precipitable water column were obtained using radiation measurements at different fixed solar zenith angles. The empirical results shown a determinant role of the solar position, a negligible effect of ozone on total shortwave radiation, and a stronger attenuation provided by aerosol particles in the erythemal radiation. A variety of aerosol types from different sources (desert dust, biomass burning, continental, and maritime) reach Malta, in this campaign several dust events from the Sahara desert occurred and were analyzed establishing the air mass back-trajectories ending at Malta at several heights calculated by means of the HYSPLIT model. Hence, changes in the UV index due to atmospheric aerosol were characterized.

The TROPOMI surface UV algorithm

NASA Astrophysics Data System (ADS)

Lindfors, Anders V.; Kujanpää, Jukka; Kalakoski, Niilo; Heikkilä, Anu; Lakkala, Kaisa; Mielonen, Tero; Sneep, Maarten; Krotkov, Nickolay A.; Arola, Antti; Tamminen, Johanna

2018-02-01

The TROPOspheric Monitoring Instrument (TROPOMI) is the only payload of the Sentinel-5 Precursor (S5P), which is a polar-orbiting satellite mission of the European Space Agency (ESA). TROPOMI is a nadir-viewing spectrometer measuring in the ultraviolet, visible, near-infrared, and the shortwave infrared that provides near-global daily coverage. Among other things, TROPOMI measurements will be used for calculating the UV radiation reaching the Earth's surface. Thus, the TROPOMI surface UV product will contribute to the monitoring of UV radiation by providing daily information on the prevailing UV conditions over the globe. The TROPOMI UV algorithm builds on the heritage of the Ozone Monitoring Instrument (OMI) and the Satellite Application Facility for Atmospheric Composition and UV Radiation (AC SAF) algorithms. This paper provides a description of the algorithm that will be used for estimating surface UV radiation from TROPOMI observations. The TROPOMI surface UV product includes the following UV quantities: the UV irradiance at 305, 310, 324, and 380 nm; the erythemally weighted UV; and the vitamin-D weighted UV. Each of these are available as (i) daily dose or daily accumulated irradiance, (ii) overpass dose rate or irradiance, and (iii) local noon dose rate or irradiance. In addition, all quantities are available corresponding to actual cloud conditions and as clear-sky values, which otherwise correspond to the same conditions but assume a cloud-free atmosphere. This yields 36 UV parameters altogether. The TROPOMI UV algorithm has been tested using input based on OMI and the Global Ozone Monitoring Experiment-2 (GOME-2) satellite measurements. These preliminary results indicate that the algorithm is functioning according to expectations.

The Nature of the UV/X-ray Absorber In PG 2302+029

NASA Technical Reports Server (NTRS)

Sabra, Bassem M.; Hamann, Fred; Jannuzi, Buell T.; George, Ian M.; Shields, Joseph C.

2003-01-01

We present Chandra X-ray observations of the radio-quiet QSO PG 2302+029. This quasar has a rare system of ultra-high velocity (-56,000 km s(exp -1) UV absorption lines that form in an outflow from the active nucleus. The Chandra data indicate that soft X-ray absorption is also present. We perform a joint UV and X-ray analysis, using photoionization calculations, to determine the nature of the absorbing gas. The UV and X-ray datasets were not obtained simultaneously. Nonetheless, our analysis suggests that the X-ray absorption occurs at high velocities in the same general region as the UV absorber. There are not enough constraints to rule out multi-zone models. In fact, the distinct broad and narrow UV line profiles clearly indicate that multiple zones are present. Our preferred estimates of the ionization and total column density in the X-ray absorber (logU = 1.6, N(sub eta) = 10(exp 22.4) cm (exp -2) over predict the O VI lambda lambda1032,1038 absorption unless the X-ray absorber is also outflowing at approximately 56,000 km s(exp-l), but they over predict the Ne VIII lambda lambda 770,780 absorption at all velocities. If we assume that the X-ray absorbing gas is outflowing at the same velocity of the UV-absorbing wind and that the wind is radiatively accelerated, then the outflow must be launched at a radius of less than or equal to 10(exp 15) cm from the central continuum source. The smallness of this radius casts doubts on the assumption of radiative acceleration.

Simulating the UV Environment For the Synthesis of Prebiotic Molecules

NASA Astrophysics Data System (ADS)

Ranjan, S.; Sasselov, D.

2014-03-01

UV radiation plays a key role in the era of biogenesis. The young Sun was more UV-active than the modern Sun (Ribas et al. 2010), and the Earth lacked an ozone layer, implying a larger UV flux both on Earth, as well as on asteroids/comets. Ultraviolet radiation can help drive prebiotic molecule synthesis (e.g., Chyba et al. 1992; Powner et al. 2009) or destroy biologically important molecules (e.g., Johns et al. 1967). These effects are wavelength dependent: they are sensitive to ionzation, bond, and ro-vibrational transition energies of biologically relevant molecules and their precursors. When simulating the environment at biogenesis it is therefore important to ensure realistic levels of UV input, in both magnitude and spectral shape. Many laboratory simulations of biomolecule synthesis under prebiotic conditions to date have been done with atomic lamps (e.g., Powner et al. 2007). These lamps are safe, stable, and affordable UV sources, well-suited for initial studies. However, their emission spectra are a poor match to prebiotic conditions: low-pressure lamps are characterized by line emission, while higher-pressure lamps do not well-reproduce the spectrum of the young Sun. In this paper, we present spectra that are more realistic approximations to prebiotic conditions. Using published opacity lists and atmospheric models, we compute the attenuation of the flux from a young Sunanalog due to water, and from the present-day Sun due to a planetary atmosphere. We compare these spectra to those emitted by lamps used in studies today, and explore the potential biological implications of the differences. We conclude by discussing possibilities for better simulating the prebiotic UV environment in lab setups.

Plant response to solar ultraviolet radiation

NASA Technical Reports Server (NTRS)

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

PAR modulation of the UV-dependent levels of flavonoid metabolites in Arabidopsis thaliana (L.) Heynh. leaf rosettes: cumulative effects after a whole vegetative growth period.

PubMed

Götz, Michael; Albert, Andreas; Stich, Susanne; Heller, Werner; Scherb, Hagen; Krins, Andreas; Langebartels, Christian; Seidlitz, Harald K; Ernst, Dieter

2010-07-01

Long-term effects of ultraviolet (UV) radiation on flavonoid biosynthesis were investigated in Arabidopsis thaliana using the sun simulators of the Helmholtz Zentrum München. The plants, which are widely used as a model system, were grown (1) at high photosynthetically active radiation (PAR; 1,310 micromol m(-2) s(-1)) and high biologically effective UV irradiation (UV-B(BE) 180 mW m(-2)) during a whole vegetative growth period. Under this irradiation regime, the levels of quercetin products were distinctively elevated with increasing UV-B irradiance. (2) Cultivation at high PAR (1,270 micromol m(-2) s(-1)) and low UV-B (UV-B(BE) 25 mW m(-2)) resulted in somewhat lower levels of quercetin products compared to the high-UV-B(BE) conditions, and only a slight increase with increasing UV-B irradiance was observed. On the other hand, when the plants were grown (3) at low PAR (540 micromol m(-2) s(-1)) and high UV-B (UV-B(BE) 180 mW m(-2)), the accumulation of quercetin products strongly increased from very low levels with increasing amounts of UV-B but the accumulation of kaempferol derivatives and sinapoyl glucose was less pronounced. We conclude (4) that the accumulation of quercetin products triggered by PAR leads to a basic UV protection that is further increased by UV-B radiation. Based on our data, (5) a combined effect of PAR and different spectral sections of UV radiation is satisfactorily described by a biological weighting function, which again emphasizes the additional role of UV-A (315-400 nm) in UV action on A. thaliana.

The effects of UV radiation A and B on diurnal variation in photosynthesis in three taxonomically and ecologically diverse microbial mats

NASA Technical Reports Server (NTRS)

Cockell, C. S.; Rothschild, L. J.

1999-01-01

Photosynthetic primary production, the basis of most global food chains, is inhibited by UV radiation. Evaluating UV inhibition is therefore important for assessing the role of natural levels of UV radiation in regulating ecosystem behavior as well as the potential impact of stratospheric ozone depletion on global ecosystems. As both photosynthesis and UV fluxes are subject to diurnal variations, we examined the diurnal variability of the effect of UV radiation on photosynthesis in three diverse algal mats. In one of the mats (Cyanidium caldarium) a small mean decrease in primary productivity over the whole day occurred when both UVA and UVB were screened out. In two of the mats (Lyngbya aestuarii and Zygogonium sp.) we found a mean increase in the total primary productivity over the day when UVB alone was screened and a further increase when UVA and UVB were both screened out. Variations in the effects of UV radiation were found at different times of the day. This diurnal variability may be because even under the same solar radiation flux, there are different factors that may control photosynthetic rate, including nutritional status and other physiological processes in the cell. The results show the importance of assessing the complete diurnal productivity. For some of the time points the increase in the mean was still within the standard deviations in primary productivity, illustrating the difficulty in dissecting UV effects from other natural variations.

A new UV-A/B protecting pigment in the terrestrial cyanobacterium Nostoc commune

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scherer, S.; Chen, T.W.; Boeger, P.

1988-12-01

A new ultraviolet (UV)-A/B absorbing pigment with maxima at 312 and 330 nanometers from the cosmopolitan terrestrial cyanobacterium Nostoc commune is described. The pigment is found in high amounts (up to 10% of dry weight) in colonies grown under solar UV radiation but only in low concentrations in laboratory cultures illuminated by artificial light without UV. Its experimental induction by UV as well as its capacity to efficiently protect Nostoc against UV radiation is reported.

UV-radiation in the past: Reconstruction and long-term changes in Austria

NASA Astrophysics Data System (ADS)

Hadzimustafic, J.; Simic, S.; Fitzka, M.

2013-05-01

Series of daily erythemal UV-dose are reconstructed for the last 30 years of the 20th century in Austria and its changes during that period with respect to observed changes in total ozone and cloud cover discussed. The reconstruction method is based on the relationship between long-term global radiation and sunshine duration records and existing measurements of erythemal UV at several locations. Through comparison with different data sources efforts are made to assure high data quality for all input parameters. The results for reconstructed daily sums show high correlations (0.95-0.99) with observed values compared on a yearly and seasonal basis throughout the overlapping period 1998-2010. Assessed from the reconstructed data, long-term variability of erythemal UV daily dose for two time periods has been quantified (1977-1995, 1996-2010). Special emphasis is put on the investigation of changes in UV due to observed trends in clouds and sunshine duration in the Austrian Alpine regions during the last decades. The earlier period shows significant changes between +4.1 %/dec and +6.9 %/dec at six stations in Austria, mainly due to significant decreases in total ozone column of up to -3.7 %/dec. Positive significant trends of around +2%/dec are found in cloud and aerosol modification factors at most of stations along with observed positive trends in sunshine duration, being statistically significant at eastern and southern stations. In spite of ozone layer recovery since the mid 1990s, the latter period does not reveal any statistically significant changes in erythemal UV irradiation.

76 FR 35672 - Revised Effectiveness Determination; Sunscreen Drug Products for Over-the-Counter Human Use

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-17

... are given ultraviolet (UV) radiation doses produced by a solar simulator (i.e., a UV lamp). Under... increasingly higher UV doses produced by the solar simulator. However, because the solar simulator can produce far higher UV radiation doses than a consumer would ever receive even under the most severe sun...

Photosynthetic carbon reduction by seagrasses exposed to ultraviolet A radiation

NASA Technical Reports Server (NTRS)

1979-01-01

The seagrasses Halophila engelmannii, Halodule wrightii, and Syringodium filiforme were examined for their intrinsic sensitivity to ultraviolet-A-UV-A and ultraviolet-B-UV-B radiation. The effect of UV-A on photosynthetically active radiation (PAR) was also determined. Ultraviolet-A and ultraviolet-B were studied with emphasis on the greater respective environmental consequence in terms of seagrass distribution and abundance. Results indicate that an intrinsic sensitivity to UV-A alone is apparent only in Halophila, while net photosynthesis in Halodule and Syringodium seems unaffected by the level of UV-A provided. The sensitivity of Halophila to UV-A in the absense of (PAR) indicates that the photosynthetic reaction does not need to be in operation for damage to occur. Other significant results are reported.

Biochemical traits and proteomic changes in postharvest flowers of medicinal chrysanthemum exposed to enhanced UV-B radiation.

PubMed

Yao, Xiaoqin; Chu, Jian-Zhou; Ma, Chun-Hui; Si, Chao; Li, Ji-Gang; Shi, Xiao-Fei; Liu, Chao-Nan

2015-08-01

The article studied UV-B effects on biochemical traits and proteomic changes in postharvest flowers of medicinal chrysanthemum. The experiment about UV-B effects on biochemical traits in flowers included six levels of UV-B treatments (0 (UV0), 50 (UV50), 200 (UV200), 400 (UV400), 600 (UV600) and 800 (UV800) μWcm(-2)). UV400, UV600 and UV800 treatments significantly increased the contents of hydrogen peroxide, malondialdehyde and UV-B absorbing compounds, and the activity of phenylalanine ammonia lyase enzyme over the control. The contents of chlorogenic acid and flavone in flowers were significantly increased by UV-B treatments (except for UV50 and UV800). Two-dimensional gel electrophoresis was utilized to analyze proteomic changes in flowers with or without UV-B radiation. Results indicated that 43 protein spots (>1.5-fold difference in volume) were detected, including 19 spots with a decreasing trend and 24 spots with an increasing trend, and 19 differentially expressed protein spots were successfully indentified by MALDI-TOF MS. The indentified proteins were classified based on functions, the most of which were involved in photosynthesis, respiration, protein biosynthesis and degradation and defence. An overall assessment using biochemical and differential proteomic data revealed that UV-B radiation could affect biochemical reaction and promote secondary metabolism processes in postharvest flowers. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of UV-B radiation on UV absorbing compounds and pigments of moss and lichen of Schirmacher oasis region, East Antarctica.

PubMed

Singh, J; Gautam, S; Bhushan Pant, A

2012-12-22

The survival of Antarctic flora under ozone depletion depends on their ability to acclimate against increasing UV—B radiation by employing photo protective mechanisms either by avoiding or repairing UV—B damage. A fifteen days experiment was designed to study moss (Bryum argenteum) and lichen (Umbilicaria aprina) under natural UV—B exposure and under UV filter frames at the Maitri region of Schirmacher oasis, East Antarctica. Changes in UV absorbing compounds, phenolics, carotenoids and chlorophyll content were studied for continuous fifteen days and significant changes were observed in the UV exposed plants of B. argenteum and U. aprina. The change in the UV absorbing compounds was more significant in B. argenteum (P<0.0001) than U. aprina (P<0.0002). The change in phenolic contents and total carotenoid content was significant (P<0.0001) in both B. argenteum and lichen U. aprina indicating that the increase in UV absorbing compounds, phenolic contents and total carotenoid content act as a protective mechanism against the deleterious effect of UV—B radiations.

Enzymological mechanism for the regulation of lanthanum chloride on flavonoid synthesis of soybean seedlings under enhanced ultraviolet-B radiation.

PubMed

Fan, Caixia; Hu, Huiqing; Wang, Lihong; Zhou, Qing; Huang, Xiaohua

2014-01-01

In order to probe into the enzymological mechanism for the regulation of lanthanum chloride (LaCl3) on flavonoid synthesis in plants under enhanced ultraviolet-B (UV-B) radiation, the effects of LaCl₃ (20 and 60 mg l(-1)) on the content of flavonoids as well as the activities of phenylalanine ammonia-lyase (PAL), cinnamate-4-hydroxylase (C4H), 4-coumarate : coenzyme A ligase (4CL), and chalcone synthase (CHS) in soybean seedlings under enhanced UV-B radiation (2.6 and 6.2 kJ m(-2) day(-1)) were investigated. Enhanced UV-B radiation (2.6 and 6.2 kJ m(-2) day(-1)) caused the increase in the content of flavonoids as well as the activities of PAL, C4H, 4CL, and CHS in soybean seedlings. The treatment of 20 mg l(-1) LaCl₃ also efficiently increased these indices, which promoted the flavonoid synthesis and provided protective effects for resisting enhanced UV-B radiation. On the contrary, the treatment of 60 mg l(-1) LaCl₃ decreased the content of flavonoids as well as the activities of C4H, 4CL, and CHS in soybean seedlings except increasing the activity of PAL, which were not beneficial to the flavonoid synthesis and provided negative effects for resisting enhanced UV-B radiation. In conclusion, enhanced UV-B radiation caused the increase in the flavonoid synthesis by promoting the activities of PAL, C4H, 4CL, and CHS in soybean seedlings. The treatment of LaCl₃ could change flavonoid synthesis in soybean seedlings under enhanced UV-B radiation by regulating the activities of PAL, C4H, 4CL, and CHS, which is an enzymological mechanism for the regulation of LaCl₃ on flavonoid synthesis in plants under enhanced UV-B radiation.

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

PubMed

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

2013-04-01

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

Effect of Surface Reflectivity Variations On Uv-visible Limb Scattering Measurements of The Atmosphere

NASA Astrophysics Data System (ADS)

Oikarinen, L.

Solar UV and visible radiation scattered at the limb of the Earth's atmosphere is used for measuring density profiles of atmosperic trace gases. For example, the OSIRIS instrument on Odin and SCIAMACHY on Envisat use this technique. A limb-viewing instrument does not see Earth's surface or tropospheric clouds directly. However, in- direct light reflected from the surface or low altitude clouds can make up tens of per cents of the signal. Furthermore, the surface area that contributes to limb intensity ex- tends over 1000 km along the instrument line-of-sight and 200 km across it. Over this area surface reflectivity can vary from almost 0% to 100%. Inaccurate modelling of reflected intensity is a potential source of error in the trace gas retrieval. Generally, radiative transfer models used for analysing limb measure- ments have to assume that the surface has a constant albedo. We have used a three- dimensional Monte Carlo radiative transfer model to study the effects of surface vari- ation to limb radiance. Based on the simulations, we have developed an approximate method for averaging surface albedo for limb scattering measurements with the help of a simple single scattering radiative transfer model.

Synergistic effect of solar radiation and solar heating to disinfect drinking water sources.

PubMed

Rijal, G K; Fujioka, R S

2001-01-01

Waterborne diseases are still common in developing countries as drinking water sources are contaminated and feasible means to reliably treat and disinfect these waters are not available. Many of these developing countries are in the tropical regions of the world where sunlight is plentiful. The objective of this study was to evaluate the effectiveness of combining solar radiation and solar heating to disinfect contaminated water using a modified Family Sol*Saver System (FSP). The non-UV transmittable cover sheet of the former FSP system was replaced with an UV transmittable plastic cover sheet to enable more wavelengths of sunlight to treat the water. Disinfection efficiency of both systems was evaluated based on reduction of the natural populations of faecal coliform, E. coli, enterococci, C. perfringens, total heterotrophic bacteria, hydrogen sulphide producing bacteria and FRNA virus. The results showed that under sunny and partly sunny conditions, water was heated to critical temperature (60 degrees C) in both the FSP systems inactivating more than 3 log (99.9%) of the concentrations of faecal coliform and E. coli to undetectable levels of < 1 CFU/100 mL within 2-5 h exposure to sunlight. However, under cloudy conditions, the two FSP systems did not reduce the concentrations of faecal indicator bacteria to levels of < 1 CFU/100 mL. Nonetheless, sufficient evidence was obtained to show that UV radiation of sunlight plus heat worked synergistically to enhance the inactivation of faecal indicator bacteria. The relative log removal of indicator microorganism in the FSP treated water was total heterotrophic bacteria < C. perfringens < F RNA virus < enterococci < E. coli < faecal coliform. In summary, time of exposure to heat and radiation effects of sunlight were important in disinfecting water by solar units. The data indicated that direct radiation of sunlight worked synergistically with solar heating of the water to disinfect the water. Thus, effective disinfection was observed even when the water temperature did not reach 60 degrees C. Finally, the hydrogen sulphide test is a simple and reliable test that householders can use to determine whether their water had been sufficiently disinfected.

In-Flight Ultraviolet Radiation on Commercial Airplanes.

PubMed

Cadilhac, Pascal; Bouton, Marie-Christine; Cantegril, Monique; Cardines, Catherine; Gisquet, Alain; Kaufman, Noël; Klerlein, Michel

2017-10-01

Epidemiological studies suggest that pilots and cabin crew have higher incidences and mortality rates of cutaneous malignant melanoma than those of the general population. Exposure to UV radiation is one of the main risk factors for this type of cancer. The aim of this study was to evaluate the level of UV radiation in an airliner in flight. Measurements were taken with a three sensor-integrated electronics UV radiometer (A, B, and C) during 14 flights from July to October 2016. They were performed during daylight hours once the airliner had reached cruising altitude. We failed to find UVC radiation. The measurements detected neither UV A nor B in any parts of the cabins of the planes tested, nor in the Airbus cockpits. UVA radiation was however found in the cockpit of Boeing 777s. But UVA levels remained well below the values found at ground level and they were also strongly reduced (more than 10 times) by cockpit sun visors. Few studies have assessed the level of UV radiation in an airplane. They suggested that the cockpit windshields reduced this type of radiation to some degree (according mainly to the wavelength of the radiation and the nature of the windshield). Our study strongly confirms these results and suggests that increased incidence of melanoma and mortality by this type of illness found among pilots and airline cabin crews may not be related to in-flight UV radiation exposure.Cadilhac P, Bouton M-C, Cantegril M, Cardines C, Gisquet A, Kaufman N, Klerlein M. In-flight ultraviolet radiation on commercial airplanes. Aerosp Med Hum Perform 2017; 88(10):947-951.

Impact of preschool environment upon children's physical activity and sun exposure.

PubMed

Boldemann, Cecilia; Blennow, Margareta; Dal, Henrik; Mårtensson, Fredrika; Raustorp, Anders; Yuen, Katarina; Wester, Ulf

2006-04-01

The physical qualities of outdoor environments are important to trigger healthy behavior in children. We studied the impact of outdoor environments upon spontaneous physical activity and exposure to ultraviolet (UV) radiation in 4- to 6-year-old children at 11 preschools in Stockholm county. In May-June 2004, pedometry and measurement of UV radiation were carried out on 197 children from 11 preschools in Stockholm county. Outdoor environments differed regarding vegetation, topography, space, and education. Ambient global UV radiation data were collected, free sky, and ground surface assessed. Arrival, in- and outdoor stay, and departure were recorded. For analysis, linear mixed model analysis was applied. In environments with trees, shrubbery, and broken ground, the mean step count/min was 21.5, and mean exposure to UV radiation as fraction of available UV during play outdoors 14.6%. In delimited environments with little vegetation, the mean step count/min was 17.7 and mean exposure fraction to UV radiation 24.3% (P < 0.001, crude). Step/min range was 8.9-30.0 (girls) and 8.8-37.2 (boys), UV radiation exposure range 4-60% (no difference between genders). Spacious preschool environments with trees, shrubbery, and broken ground trigger physical activity and yield sun protection in outdoor play. As many children attend preschool, access to such environments is recommended in community architecture.

The effect of melatonin on eye lens of rats exposed to ultraviolet radiation.

PubMed

Anwar, M M; Moustafa, M A

2001-05-01

We investigated the influence of exogenously administered melatonin on adult rats eye lenses exposed to ultraviolet radiation (UV) A and B ranging from 356-254 nm irradiation at 8 microW/cm(2). Rats exposed to this range of UV for 15 min for one week showed a significant (P<0.05) reduction in antioxidant enzymes activities; superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and elevated (P<0.001) lipid peroxidation served as an index of cellular damage by free radicals. UV-radiation significantly (P<0.001) elevated calcium ions (Ca(2+)) and lactate dehydrogenase (LDH) activity in lenses. Depleting animals of their stores of important intracellular antioxidant and elevating lenticular Ca(2+) by UV irradiation, may be the main cause of lens opacification. Melatonin injection with radiation significantly reduced (P<0.05) lipid peroxidation, Ca(2+) and (P<0.001) for LDH. When melatonin was injected after radiation, SOD and GSH-Px enzyme activities increased significantly (P<0.01), and lipid peroxidation, Ca(2+) levels and LDH activities were reduced significantly. Melatonin injection after UV radiation was as effective as melatonin treatment concurrent with UV irradiation. We conclude that melatonin may protect the eye lens from the damaging effects of UV exposure, and its actions protect lens from oxidative stress, elevating Ca(2+) levels, which are considered as an important causes of cataractogenesis.

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

NASA Astrophysics Data System (ADS)

Gomes, L. M.; Ventura, L.

2018-02-01

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

Exclusion of solar UV radiation improves photosynthetic performance and yield of wheat varieties.

PubMed

Kataria, Sunita; Guruprasad, K N

2015-12-01

Field studies were conducted to determine the potential for alterations in photosynthetic performance and grain yield of four wheat (Triticum aestivum) varieties of India- Vidisha, Purna, Swarna and Naveen Chandausi by ambient ultraviolet radiation (UV). The plants were grown in specially designed UV exclusion chambers, wrapped with filters that excluded UV-B (<315 nm), UV-A/B (<400 nm) or transmitted ambient UV or lacked filters. The results indicated that solar UV exclusion increased the leaf mass per area ratio, leaf weight ratio and chlorophylls per unit area of flag leaves in all the four varieties of wheat. Polyphasic chlorophyll a fluorescence transients from the flag leaves of UV excluded wheat plants gave a higher fluorescence yield. Exclusion of solar UV significantly enhanced photosynthetic performance as a consequence of increased efficiency of PS II, performance index (PIABS) and rate of photosynthesis in the flag leaves of wheat varieties along with a remarkable increase in carbonic anhydrase, Rubisco and nitrate reductase activities. This additional fixation of carbon and nitrogen by exclusion of UV was channelized towards the improvement in grain yield of wheat varieties as there was a decrease in the UV-B absorbing substances and an increase in soluble protein content in flag leaves of all the four varieties of wheat. The magnitude of response for UV exclusion for all the measured parameters was higher in two varieties of wheat Vidisha and Purna as compared to Swarna and Naveen Chandausi. Cumulative stress response index (CSRI) for each variety was developed from the cumulative sum of physiological and yield parameters such as leaf mass area ratio of flag leaf, total chlorophyll content, performance index at absorption basis, rate of photosynthesis and grain yield. All the varieties had a negative CSRI, demonstrating a negative impact of ambient UV radiation. Naveen Chandausi and Swarna are less sensitive to ambient UV radiation; Vidisha is more sensitive to both UV-A and UV-B and Purna is more sensitive to ambient UV-B radiation. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Dual Band Deep Ultraviolet AlGaN Photodetectors

NASA Technical Reports Server (NTRS)

Aslam, S.; Miko, L.; Stahle, C.; Franz, D.; Pugel, D.; Guan, B.; Zhang, J. P.; Gaska, R.

2007-01-01

We report on the design, fabrication and characterization of a back-illuminated voltage bias selectable dual-band AlGaN UV photodetector. The photodetector can separate UVA and W-B band radiation by bias switching a two terminal n-p-n homojunction structure that is fabricated in the same pixel. When a forward bias is applied between the top and bottom electrodes, the detector can sense UV-A and reject W-B band radiation. Alternatively, under reverse bias, the photodetector can sense UV-B and reject UV-A band radiation.

Diurnal changes in CN metabolism and response of rice seedlings to UV-B radiation.

PubMed

Yun, Hyejin; Lim, Sunhyung; Kim, Yangmin X; Lee, Yejin; Lee, Seulbi; Lee, Deogbae; Park, Keewoong; Sung, Jwakyung

2018-03-13

Plants regulate a number of primary metabolites, including carbohydrates, organic acids, and amino acids, in response to UV-B radiation. Therefore, it is essential to understand the time-dependent response of rice plants to UV-B stress. This study focused on the response of plants to UV-B at different leaf developmental phases (emerging, growing, and maturing) in an attempt to fully comprehend the metabolic shift. We analyzed the expression levels of genes related to starch/sucrose metabolism in the leaf blades of rice seedlings (Oryza sativa L. "Saechuchenog") exposed to UV-B irradiation for short (1 day) and long terms (5 days) using quantitative real-time polymerase chain reaction. We also examined the diurnal variations in the contents of primary metabolites using an established GCTOF-MS (gas chromatography time of flight-mass spectrometry) method. The results showed that the levels of primary metabolites were largely dependent upon the diurnal rhythm and leaf developmental phase. The young leaves (sink) produced and accumulated starch rather than sucrose. The short-term (4 h, 1 day) UV-B exposure inhibited sucrose synthesis, which could be the first target of UV-B radiation. Following short- and long-term (5 days) exposure to UV-B radiation, the dynamic response of primary metabolites was evaluated. It was found that the content of carbohydrates decreased throughout the period of exposure to UV-B stress, especially in terms of sucrose concentration. However, the content of the majority of amino acids increased after an early decrease. Our data revealed that the metabolic response, as well as the gene expression, differed with the period (intensity) of exposure to UV-B radiation and with the phase of leaf development. These findings provide new insights for a better understanding of the metabolic response of a variety of plant species exposed to a wide range of UV-B radiation. Copyright © 2018. Published by Elsevier GmbH.

Evaluating Ultraviolet Radiation Exposures Determined from TOMS Satellite Data at Sites of Amphibian Declines in Central and South America

NASA Technical Reports Server (NTRS)

Middleton, Elizabeth M.; Smith, David E. (Technical Monitor)

2000-01-01

Many amphibian species have experienced substantial population declines, or have disappeared altogether, during the last several decades at a number of amphibian census sites in Central and South America. This study addresses the use of satellite-derived trends in solar ultraviolet-B (UV-B; 280-320 nm) radiation exposures at these sites over the last two decades, and is intended to demonstrate a role for satellite observations in determining whether UV-B radiation is a contributing factor in amphibian declines. UV-B radiation levels at the Earth's surface were derived from the Total Ozone Mapping Spectrometer (TOMS) satellite data, typically acquired daily since 1979. These data were used to calculate the daily erythemal (sunburning) UV-B, or UV-B(sub ery), exposures at the latitude, longitude, and elevation of each of 20 census sites. The annually averaged UV-B(sub ery) dose, as well as the maximum values, have been increasing in both Central and South America, with higher levels received at the Central American sites. The annually averaged UV-B(sub ery) exposures increased significantly from 1979-1998 at all 11 Central American sites examined (r(exp 2) = 0.60 - 0.79; P<=0.015), with smaller but significant increases at five of the nine South American sites (r(exp 2) = 0.24-0.42; P<=0.05). The contribution of the highest UV-B(sub ery) exposure levels (>= 6750 J/sq m*d) to the annual UV-B(sub ery) total has increased from approx. 5% to approx. 15% in Central America over the 19 year period, but actual daily exposures for each species are unknown. Synergy among UV-B radiation and other factors, especially those associated with alterations of water chemistry (e.g., acidification) in aqueous habitats is discussed. These findings justify further research concerning whether UV-B(sub ery) radiation plays a role in amphibian population declines and extinctions.

Induction of wound-periderm-like tissue in Kalanchoe pinnata (Lam.) Pers. (Crassulaceae) leaves as a defence response to high UV-B radiation levels

PubMed Central

Nascimento, Luana Beatriz dos Santos; Moreira, Nattacha dos Santos; Leal-Costa, Marcos Vinícius; Costa, Sônia Soares; Tavares, Eliana Schwartz

2015-01-01

Background and Aims UV-B radiation can be stressful for plants and cause morphological and biochemical changes. Kalanchoe pinnata is a CAM leaf-succulent species distributed in hot and dry regions, and is rich in flavonoids, which are considered to be protective against UV-B radiation. This study aims to verify if K. pinnata has morphological or anatomical responses as a strategy in response to high UV-B levels. Methods Kalanchoe pinnata plants of the same age were grown under white light (control) or white light plus supplemental UV-B radiation (5 h d–1). The plants were treated with the same photoperiod, photosynthetically active radiation, temperature and daily watering system. Fragments of the middle third of the leaf blade and petiole were dehydrated and then embedded in historesin and sectioned in a rotary microtome. Sections were stained with toluidine blue O and mounted in Entellan®. Microchemical analyses by optical microscopy were performed on fresh material with Sudan III, Sudan IV and phloroglucinol, and analysed using fluorescence microscopy. Key Results Supplemental UV-B radiation caused leaf curling and the formation of brown areas on the leaves. These brown areas developed into a protective tissue on the adaxial side of the leaf, but only in directly exposed regions. Anatomically, this protective tissue was similar to a wound-periderm, with outer layer cell walls impregnated with suberin and lignin. Conclusions This is the first report of wound-periderm formation in leaves in response to UV-B radiation. This protective tissue could be important for the survival of the species in desert regions under high UV-B stress conditions. PMID:26346722

UV reflection properties of plumage and skin of domesticated turkeys (Meleagris gallopavo f. dom.) as revealed by UV photography.

PubMed

Bartels, T; Lütgeharm, J-H; Wähner, M; Berk, J

2017-12-01

Reflection and fluorescence properties of feathered and non-feathered body regions of white- and bronze-colored fattening turkeys of various ages were examined by ultraviolet (UV) photography. The examinations were carried out on 20 white-feathered fattening turkeys (B.U.T. 6; 10 males, 10 females) and 20 bronze-feathered fattening turkeys (Grelier 708; 10 males, 10 females) over a period of 21 weeks. The turkeys were photographed once a wk under long-wave UV (UVA) radiation illumination (λ = 344-407 nm) using a digital camera. A bandpass filter was used for UV reflectography to filter out the visible components of the used light source. A longpass filter was used for UV fluorescence photography to avoid blurring in the image due to chromatic aberration as a result of UV illumination. We found that natal down feathers of white-feathered turkeys showed an intense yellowish-green fluorescence under UVA light. UVA fluorescence also was shown by the natal downs of the slightly melanized plumage areas of bronze turkeys. Vaned feathers of white fattening turkeys reflected UVA radiation. Freshly molted feathers were optically distinguishable from the previous feather generation due to their more intense UVA reflection. In bronze turkeys, both the bright end seams of the dark pennaceous feathers and rectrices and the bright banding of primary and secondary remiges reflected UVA radiation. Intense UVA fluorescence was recognizable in day-old chicks of both color variants on the scutellate scales of the legs and toes. In male turkeys of both color variants, UVA-reflecting parts were recognizable with increasing age on the featherless head region. The UVA-fluorescent and UVA-reflective characteristics of the plumage of fattening turkeys were closely related to the plumage color, the feather type, the molting state, and the age of the birds. Further research is needed regarding the UVA-reflecting properties of the turkey plumage and the effects of full-spectrum illumination, including the UVA spectrum, on the behavior and health of fattening turkeys. © 2017 Poultry Science Association Inc.

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

NASA Astrophysics Data System (ADS)

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

2003-11-01

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

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Orth, A.B.; Teramura, A.H.; Sisler, H.D.

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 ofmore » 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.« less

The effects of simulated solar UVB radiation on early developmental stages of the Northwestern Salamander (Ambystoma gracile) from three lakes

USGS Publications Warehouse

Calfee, Robin D.; Little, Edward E.; Pearl, Christopher A.; Hoffman, Robert L.

2010-01-01

Solar ultraviolet radiation (UV) has received much attention as a factor that could play a role in amphibian population declines. UV can be hazardous to some amphibians, but the resultant effects depend on a variety of environmental and behavioral factors. In this study, the potential effects of UV on the Northwestern Salamander, Ambystoma gracile, from three lakes were assessed in the laboratory using a solar simulator. We measured the survival of embryos and the survival and growth of larvae exposed to four UV treatments in controlled laboratory studies, the UV absorbance of egg jelly, oviposition depths in the lakes, and UV absorbance in water samples from the three lakes. Hatching success of embryos decreased in the higher UV treatments as compared to the control treatments, and growth of surviving larvae was significantly reduced in the higher UVB irradiance treatments. The egg jelly exhibited a small peak of absorbance within the UVB range (290–320 nm). The magnitude of UV absorbance differed among egg jellies from the three lakes. Oviposition depths at the three sites averaged 1.10 m below the water surface. Approximately 66% of surface UVB radiation was attenuated at 10-cm depth in all three lakes. Results of this study indicate that larvae may be sensitive to UVB exposure under laboratory conditions; however, in field conditions the depths of egg deposition in the lakes, absorbance of UV radiation by the water column, and the potential for behavioral adjustments may mitigate severe effects of UV radiation.

Effects of simulated solar UVB radiation on early developmental stages of the northwestern salamander (Ambystoma gracile) from three lakes

USGS Publications Warehouse

Calfee, R.D.; Little, E.E.; Pearl, C.A.; Hoffman, R.L.

2010-01-01

Solar ultraviolet radiation (UV) has received much attention as a factor that could play a role in amphibian population declines. UV can be hazardous to some amphibians, but the resultant effects depend on a variety of environmental and behavioral factors. In this study, the potential effects of UV on the Northwestern Salamander, Ambystoma gracile, from three lakes were assessed in the laboratory using a solar simulator. We measured the survival of embryos and the survival and growth of larvae exposed to four UV treatments in controlled laboratory studies, the UV absorbance of egg jelly, oviposition depths in the lakes, and UV absorbance in water samples from the three lakes. Hatching success of embryos decreased in the higher UV treatments as compared to the control treatments, and growth of surviving larvae was significantly reduced in the higher UVB irradiance treatments. The egg jelly exhibited a small peak of absorbance within the UVB range (290-320 nm). The magnitude of UV absorbance differed among egg jellies from the three lakes. Oviposition depths at the three sites averaged 1.10 m below the water surface. Approximately 66 of surface UVB radiation was attenuated at 10-cm depth in all three lakes. Results of this study indicate that larvae may be sensitive to UVB exposure under laboratory conditions; however, in field conditions the depths of egg deposition in the lakes, absorbance of UV radiation by the water column, and the potential for behavioral adjustments may mitigate severe effects of UV radiation. Copyright 2010 Society for the Study of Amphibians and Reptiles.

Monitoring the High-Energy Radiation Environment of Exoplanets around Lowmass Stars with SPARCS (Star-Planet Activity Research CubeSat)

NASA Astrophysics Data System (ADS)

Shkolnik, Evgenya

Seventy-five billion M dwarfs in our galaxy host at least one small planet in the habitable zone (HZ). The stellar ultraviolet (UV) radiation from M dwarfs is strong and highly variable, and impacts planetary atmospheric loss, composition and habitability. These effects are amplified by the extreme proximity of their HZs (0.1–0.4 AU). JWST will characterize HZ M dwarf planets and attempt the first spectroscopic search for life beyond the Solar System. Knowing the UV environments of M dwarf planets will be crucial to understanding their atmospheric composition and a key parameter in discriminating between biological and abiotic sources for observed biosignatures. The UV flux emitted during the super-luminous premain sequence phase of M stars drives water loss and photochemical O2 buildup for terrestrial planets within the HZ. This phase can persist for up to a billion years for the lowest mass M stars. Afterwards, UV-driven photochemistry during the main sequence phase strongly affects a planet’s atmosphere, could limit the planet’s potential for habitability, and may confuse studies of habitability by creating false chemical biosignatures. Our proposed CubeSat observatory will be the first mission to provide the time-dependent spectral slope, intensity and evolution of M dwarf stellar UV radiation. These measurements are crucial to interpreting observations of planetary atmospheres around low-mass stars. Mission: The Star-Planet Activity Research CubeSat (SPARCS) will be a 6U CubeSat devoted to monitoring 25 M stars in two UV bands: SPARCS far-UV (S- FUV: 153–171 nm) and SPARCS near-UV (S-NUV: 260– 300 nm). For each target, SPARCS will observe continuously between one and three complete stellar rotations (4–45 days) over a mission lifetime of 2 years. A UV characterization survey of M dwarfs, the most common of planet hosts, is a perfect experiment for a CubeSat: - UV astronomy cannot be done from the ground because of Earth’s atmospheric absorption. - Photometry of nearby sources is an efficient use of a small aperture. - Unlike the HST, whose time is shared among many instruments and programs, a CubeSat can provide dedicated space-based long-term monitoring in the UV. Technology: SPARCS will advance UV detector technology by flying high quantum efficiency (QE), UV-optimized detectors developed at JPL. These “delta-doped” detectors have a long history of deployment demonstrating greater than 5x the sensitivity of the detectors used by GALEX. SPARCS will pave the way for their application in missions like LUVOIR or HabEx. Education: The SPARCS research program will train future scientists and mission leaders by mentoring five undergraduate students, three graduate students, and two post-doctoral scholars throughout all aspects of the mission, including engineering, science, data management and outreach. Relevance to NASA: The SPARCS mission will address NASA’s goals of identifying the characteristics and distribution of potentially habitable environments, including HZ planet hosts like Proxima and TRAPPIST-1. SPARCS will also be capable of ‘targetofopportunity’ UV observations of NASA’s TESS yield of rocky planets in M dwarf HZs, some of the first HZ planets to be spectroscopically characterized by JWST. SPARCS can provide the needed UV context for the interpretation of transmission and emission spectra of these potentially habitable planets. Further into the future, SPARCS results will inform the target strategy for the enormous telescopic investments in exoplanet science of LUVOIR or HabEx. SPARCS’ technology will fill a gap in NASA’s capabilities to observe low-mass stellar/planetary systems in the FUV and NUV. HST’s UV capabilities will not last much later than 2019, with future opportunities (e.g., LUVOIR) not arriving until sometime after 2035. The detector technology of this CubeSat will play a crucial role in these and interim UV-capable missions.

Repression of Growth Regulating Factors by the MicroRNA396 Inhibits Cell Proliferation by UV-B Radiation in Arabidopsis Leaves[C][W

PubMed Central

Casadevall, Romina; Rodriguez, Ramiro E.; Debernardi, Juan M.; Palatnik, Javier F.; Casati, Paula

2013-01-01

Because of their sessile lifestyle, plants are continuously exposed to solar UV-B radiation. Inhibition of leaf growth is one of the most consistent responses of plants upon exposure to UV-B radiation. In this work, we investigated the role of GROWTH-REGULATING FACTORs (GRFs) and of microRNA miR396 in UV-B–mediated inhibition of leaf growth in Arabidopsis thaliana plants. We demonstrate that miRNA396 is upregulated by UV-B radiation in proliferating tissues and that this induction is correlated with a decrease in GRF1, GRF2, and GRF3 transcripts. Induction of miR396 results in inhibition of cell proliferation, and this outcome is independent of the UV-B photoreceptor UV resistance locus 8, as well as ATM AND RAD3–RELATED and the mitogen-activated protein kinase MPK6, but is dependent on MPK3. Transgenic plants expressing an artificial target mimic directed against miR396 (MIM396) with a decrease in the endogenous microRNA activity or plants expressing miR396-resistant copies of several GRFs are less sensitive to this inhibition. Consequently, at intensities that can induce DNA damage in Arabidopsis plants, UV-B radiation limits leaf growth by inhibiting cell division in proliferating tissues, a process mediated by miR396 and GRFs. PMID:24076976

Solar UV-B radiation and ethylene play a key role in modulating effective defenses against Anticarsia gemmatalis larvae in field-grown soybean.

PubMed

Dillon, Francisco M; Tejedor, M Daniela; Ilina, Natalia; Chludil, Hugo D; Mithöfer, Axel; Pagano, Eduardo A; Zavala, Jorge A

2018-02-01

Solar UV-B radiation has been reported to enhance plant defenses against herbivore insects in many species. However, the mechanism and traits involved in the UV-B mediated increment of plant resistance are unknown in crops species, such as soybean. Here, we studied defense-related responses in undamaged and Anticarsia gemmatalis larvae-damaged leaves of two soybean cultivars grown under attenuated or full solar UV-B radiation. We determined changes in jasmonates, ethylene (ET), salicylic acid, trypsin protease inhibitor activity, flavonoids, and mRNA expression of genes related with defenses. ET emission induced by Anticarsia gemmatalis damage was synergistically increased in plants grown under solar UV-B radiation and was positively correlated with malonyl genistin concentration, trypsin proteinase inhibitor activity and expression of IFS2, and the pathogenesis protein PR2, while was negatively correlated with leaf consumption. The precursor of ET, aminocyclopropane-carboxylic acid, applied exogenously to soybean was sufficient to strongly induce leaf isoflavonoids. Our results showed that in field-grown soybean isoflavonoids were regulated by both herbivory and solar UV-B inducible ET, whereas flavonols were regulated by solar UV-B radiation only and not by herbivory or ET. Our study suggests that, although ET can modulate UV-B-mediated priming of inducible plant defenses, some plant defenses, such as isoflavonoids, are regulated by ET alone. © 2017 John Wiley & Sons Ltd.

Are there mechanistic differences between ultraviolet and visible radiation induced skin pigmentation?

PubMed

Ramasubramaniam, Rajagopal; Roy, Arindam; Sharma, Bharati; Nagalakshmi, Surendra

2011-12-01

Most of the studies on sunlight-induced pigmentation of skin are mainly focused on ultraviolet (UV) radiation-induced pigmentation and ways to prevent it. Recent studies have shown that the visible component of sunlight can also cause significant skin pigmentation. In the current study, the extent of pigmentation induced by UV and visible regions of sunlight in subjects with Fitzpatrick skin type IV-V was measured and compared with pigmentation induced by total sunlight. The immediate pigment darkening (IPD) induced by the visible fraction of sunlight is not significantly different from that induced by the UV fraction. However, the persistent pigment darkening (PPD) induced by visible fraction of sunlight in significantly lower than that induced by the UV fraction. The dose responses of IPD induced by UV, visible light and total sunlight suggest that both UV and visible light interact with the same precursor although UV is 25 times more efficient in inducing pigmentation per J cm(-2) of irradiation compared to visible radiation. The measured diffused reflection spectra and decay kinetics of UV and visible radiation-induced pigmentation are very similar, indicating that the nature of the transient and persistent species involved in both the processes are also likely to be same.

Hope and challenge: the importance of ultraviolet (UV) radiation for cutaneous vitamin D synthesis and skin cancer.

PubMed

Reichrath, Jörg; Reichrath, Sandra

2012-01-01

Abstract Solar ultraviolet (UV)-radiation is the most important environmental risk factor for the development of non-melanoma skin cancer (most importantly basal and squamous cell carcinomas), that represent the most common malignancies in Caucasian populations. To prevent these malignancies, public health campaigns were developed to improve the awareness of the general population of the role of UV-radiation. The requirements of vitamin D is mainly achieved by UV-B-induced cutaneous photosynthesis, and the vitamin D-mediated positive effects of UV-radiation were not always adequately considered in these campaigns; a strict "no sun policy" might lead to vitamin D-deficiency. This dilemma represents a serious problem in many populations, for an association of vitamin D-deficiency and multiple independent diseases has been convincingly demonstrated. It is crucial that guidelines for UV-exposure (e.g. in skin cancer prevention campaigns) consider these facts and give recommendations how to prevent vitamin D-deficiency. In this review, we analyze the present literature to help developing well-balanced guidelines on UV-protection that ensure an adequate vitamin D-status without increasing the risk to develop UV-induced skin cancer.

An ultraviolet simulator for the incident Martian surface radiation and its applications

NASA Astrophysics Data System (ADS)

Kolb, C.; Abart, R.; Bérces, A.; Garry, J. R. C.; Hansen, A. A.; Hohenau, W.; Kargl, G.; Lammer, H.; Patel, M. R.; Rettberg, P.; Stan-Lotter, H.

2005-10-01

Ultraviolet (UV) radiation can act on putative organic/biological matter at the Martian surface in several ways. Only absorbed, but not transmitted or reflected, radiation energy can be photo-chemically effective. The most important biological UV effects are due to photochemical reactions in nucleic acids, DNA or RNA, which constitute the genetic material of all cellular organisms and viruses. Protein or lipid effects generally play a minor role, but they are also relevant in some cases. UV radiation can induce wavelengths-specific types of DNA damage. At the same time it can also induce the photo-reversion reaction of a UV induced DNA photoproduct of nucleic acid bases, the pyrimidine dimers. Intense UVB and UVC radiation, experienced on early Earth and present-day Mars, has been revealed to be harmful to all organisms, including extremophile bacteria and spores. Moreover, the formation of oxidants, catalytically produced in the Martian environment through UV irradiation, may be responsible for the destruction of organic matter on Mars. Following this, more laboratory simulations are vital in order to investigate and understand UV effects on organic matter in the case of Mars. We have designed a radiation apparatus that simulates the anticipated Martian UV surface spectrum between 200 and 400 nm (UVC UVA). The system comprises a UV enhanced xenon arc lamp, special filter-sets and mirrors to simulate the effects of the Martian atmospheric column and dust loading. We describe the technical setup and performance of the system and discuss its uses for different applications. The design is focused on portability, therefore, the Mars-UV simulator represents a device for several different Mars simulation facilities with specific emphasis on Mars research topics.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aljawi, Ohoud; Gopir, Geri; Duay, Abdul Basit

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 ofmore » 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}.« less

Transmittance of tinted and UV-blocking disposable contact lenses.

PubMed

Harris, M G; Haririfar, M; Hirano, K Y

1999-03-01

Tinted and ultraviolet (UV)-blocking disposable contact lenses have become increasingly popular over the last decade. Wearers of UV-blocking contact lenses could benefit greatly by protecting their eyes from potential UV radiation damage. A Uvikon 930 dual beam spectrophotometer was used to measure three enhancement-tinted lenses (royal blue, evergreen, and aqua), two types of UV-blocking lenses, and two types of non-UV-blocking lenses. Enhancement-tinted lenses did show a decrease in transmittance at certain wavelengths on the visible spectrum, but they did not reduce the transmittance of UV radiation to the extent of the UV-blocking lenses designed specifically for this purpose.

Evaluating optical hazards from plasma arc cutting.

PubMed

Glassford, Eric; Burr, Gregory

2018-01-01

The Health Hazard Evaluation Program of the National Institute for Occupational Safety and Health evaluated a steel building materials manufacturer. The employer requested the evaluation because of concerns about optical radiation hazards from a plasma arc cutting system and the need to clarify eye protection requirements for plasma operators, other employees, and visitors. The strength of the ultraviolet radiation, visible radiation (light), and infrared radiation generated by the plasma arc cutter was measured at various distances from the source and at different operating amperages. Investigators also observed employees performing the plasma arc cutting. Optical radiation above safe levels for the unprotected eyes in the ultraviolet-C, ultraviolet-B, and visible light ranges were found during plasma arc cutting. In contrast, infrared and ultraviolet-A radiation levels during plasma arc cutting were similar to background levels. The highest non-ionizing radiation exposures occurred when no welding curtains were used. A plasma arc welding curtain in place did not eliminate optical radiation hazards to the plasma arc operator or to nearby employees. In most instances, the measured intensities for visible light, UV-C, and UV-B resulted in welding shade lens numbers that were lower than those stipulated in the OSHA Filter Lenses for Protection Against Radiant Energy table in 29 CFR 1910.133(a)(5). [1] Investigators recommended using a welding curtain that enclosed the plasma arc, posting optical radiation warning signs in the plasma arc cutter area, installing audible or visual warning cues when the plasma arc cutter was operating, and using welding shades that covered the plasma arc cutter operator's face to protect skin from ultraviolet radiation hazards.

Induction of secondary metabolite production by UV-C radiation in Vitis vinifera L. Öküzgözü callus cultures.

PubMed

Cetin, Emine Sema

2014-09-04

The aim of the present work was to examine the role of UV-C irradiation on the production of secondary metabolites (total phenolic, total flavanols, total flavonols, catechin, ferulic acid and trans-resveratrol in phenolic compounds and α-, β-, γ- δ-tocopherols) in callus cultures. Studies on the effects of UV-C treatment on callus culture are seldom and generally focused on UV-B. However UV-C radiation play an important role in accumule secondary metabolites. In this study, callus cultures from Öküzgözü grape cultivar were initiated from leaf petiole explants. Calli formed after 6 weeks on the medium supplemented with 0.5 mg L-1 benzylaminopurine (BA), 0.5 mg L-1 indole acetic acid (IAA) on B5 media. Callus tissues were exposed to UV-C irradiation at 10, 20 and 30 cm distances from the UV source for 5 and 10 minutes and samples were collected at hours 0, 24 and 48. The greatest total phenolic content (155.14 mg 100 g-1) was detected in calli exposed to UV-C for 5 min from 30 cm distance and sampled after 24 h. 24 h and 48 h incubation times, 30 cm and 5 min were the most appropriate combination of UV-C application in total flavanol content. Maximum total flavonol content (7.12 mg 100 g-1) was obtained on 0 h, 5 min and 20 cm combination. The highest (+)- catechin accumulation (8.89 mg g-1) was found in calli with 10 min UV-C application from 30 cm distance and sampled after 48 h. Ferulic acid content increased 6 fold in Öküzgözü callus cultures (31.37 μg g-1) compared to the control group. The greatest trans-resveratrol content (8.43 μg g-1) was detected in calli exposed to UV-C for 5 min from 30 cm distance and sampled after 24 h. The highest α-tocopherol concentration was found in calli exposed to UV-C for 10 min from 30 cm distance and sampled after 24 h. As a conclusion, it was showed that UV-C radiation had remarkable promoting effects on the accumulation of secondary metabolites in the calli of Öküzgözü grape cultivar.

Assessment of UV biological spectral weighting functions for phenolic metabolites and growth responses in silver birch seedlings.

PubMed

Kotilainen, Titta; Venäläinen, Tuulia; Tegelberg, Riitta; Lindfors, Anders; Julkunen-Tiitto, Riitta; Sutinen, Sirkka; O'Hara, Robert B; Aphalo, Pedro J

2009-01-01

In research concerning stratospheric ozone depletion, action spectra are used as biological spectral weighting functions (BSWFs) for describing the effects of UV radiation on plant responses. Our aim was to evaluate the appropriateness of six frequently used BSWFs that differ in effectiveness with increasing wavelength. The evaluation of action spectra was based on calculating the effective UV radiation doses according to 1-2) two formulations of the generalized plant action spectrum, 3) a spectrum for ultraviolet induced erythema in human skin, 4) a spectrum for the accumulation of a flavonol in Mesembryanthemum crystallinum, 5) a spectrum for DNA damage in alfalfa seedlings and 6) the plant growth action spectrum. We monitored effects of UV radiation on the concentration of individual UV absorbing metabolites and chlorophyll concentrations in leaves and growth responses of silver birch (Betula pendula) seedlings. Experiments were conducted outdoors using plastic films attenuating different parts of the UV spectrum. Chlorophyll concentrations and growth were not affected by the UV treatments. The response to UV radiation varied between and within groups of phenolics. In general, the observed responses of phenolic groups and individual flavonoids were best predicted by action spectra extending into the UV-A region with moderate effectiveness.

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

PubMed

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

2018-02-01

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

Highly Sensitive Detection of UV Radiation Using a Uranium Coordination Polymer.

PubMed

Liu, Wei; Dai, Xing; Xie, Jian; Silver, Mark A; Zhang, Duo; Wang, Yanlong; Cai, Yawen; Diwu, Juan; Wang, Jian; Zhou, Ruhong; Chai, Zhifang; Wang, Shuao

2018-02-07

The accurate detection of UV radiation is required in a wide range of chemical industries and environmental or biological related applications. Conventional methods taking advantage of semiconductor photodetectors suffer from several drawbacks such as sophisticated synthesis and manufacturing procedure, not being able to measure the accumulated UV dosage as well as high defect density in the material. Searching for new strategies or materials serving as precise UV dosage sensor with extremely low detection limit is still highly desirable. In this work, a radiation resistant uranium coordination polymer [UO 2 (L)(DMF)] (L = 5-nitroisophthalic acid, DMF = N,N-dimethylformamide, denoted as compound 1) was successfully synthesized through mild solvothermal method and investigated as a unique UV probe with the detection limit of 2.4 × 10 -7 J. On the basis of the UV dosage dependent luminescence spectra, EPR analysis, single crystal structure investigation, and the DFT calculation, the UV-induced radical quenching mechanism was confirmed. Importantly, the generated radicals are of significant stability which offers the opportunity for measuring the accumulated UV radiation dosage. Furthermore, the powder material of compound 1 was further upgraded into membrane material without loss in luminescence intensity to investigate the real application potentials. To the best of our knowledge, compound 1 represents the most sensitive coordination polymer based UV dosage probe reported to date.

An investigation of solar erythemal ultraviolet radiation at two sites in tourist attraction areas of Thailand

NASA Astrophysics Data System (ADS)

Buntoung, Sumaman; Pattarapanitchai, Somjet; Wattan, Rungrat; Masiri, Itsara; Promsen, Worrapass; Tohsing, Korntip; Janjai, Serm

2013-05-01

Islands on the southern coasts of Thailand are famous attractions for local and foreign tourists. Tourists usually expose their skins to solar radiation for tanning. Thus information on solar ultraviolet radiation (UV) is of importance for tourists to protect themselves from adverse effects of UV. In this work, solar erythemal ultraviolet radiation (EUV) at two touristic sites namely Samui island (9.451°N, 100.033°E) and Phuket island (8.104°N, 98.304°E) was investigated. In investigating EUV, broadband UV radiometers (Kipp & Zonen, model UVS-B-C) were installed at existing meteorological stations in Samui and Phuket islands. A one-year period of EUV data from these two sites was analyzed. The level of UV index at these sites was studied. The values of UV index higher than 12 at noon time of clear days are usually found in the summer at both sites. Seasonal variation of EUV at both sites was investigated. It was found that the tropical monsoons have strong influence on this variation. Finally, global broadband radiation measured at the sites was also used to establish a correlation between EUV and global broadband radiation. Higher correlation was found for the case of clear sky, as compared to the case of cloudy sky. The correlation obtained from this analysis can be used to estimate EUV from global broadband radiation at these two sites.

Implications of mycosporine-like amino acid and antioxidant defenses in UV-B radiation tolerance for the algae species Ptercladiella capillacea and Gelidium amansii.

PubMed

Lee, Tse-Min; Shiu, Chia-Tai

2009-02-01

Ultraviolet-B (UV-B) radiation (0.5, 1.0, 1.5, and 3.0Wm(-2)) induced higher H(2)O(2) production and lipid peroxidation in alga Gelidium amansii inhabiting in lower subtidal regions than upper subtidal alga Ptercladiella capillacea. Compared to G. amansii, mycosporine-like amino acid (MAA) concentration in P. capillacea was higher and can be increased by 0.5-1.0Wm(-2) UV-B, while carotenoid concentration was lower but also increased by 1.5-3.0Wm(-2) UV-B. UV-B increased ascorbate concentration, but to a higher degree in P. capillacea. UV-B decreased glutathione concentration, but to a higher degree in G. amansii. UV-B increased ascorbate peroxidase (APX) and glutathione reductase (GR) activities in P.capillacea but decreased them in G. amansii. UV-B increased superoxide dismutase and catalase activities, but to a higher degree in G. amansii. So, G. amansii suffered greater oxidative stress from UV-B radiation. P. capillacea can effectively reduce UV-B sensitivity by increasing sunscreen ability and antioxidant defense capacity.

Experimental evaluation of optimization method for developing ultraviolet barrier coatings

NASA Astrophysics Data System (ADS)

Gonome, Hiroki; Okajima, Junnosuke; Komiya, Atsuki; Maruyama, Shigenao

2014-01-01

Ultraviolet (UV) barrier coatings can be used to protect many industrial products from UV attack. This study introduces a method of optimizing UV barrier coatings using pigment particles. The radiative properties of the pigment particles were evaluated theoretically, and the optimum particle size was decided from the absorption efficiency and the back-scattering efficiency. UV barrier coatings were prepared with zinc oxide (ZnO) and titanium dioxide (TiO2). The transmittance of the UV barrier coating was calculated theoretically. The radiative transfer in the UV barrier coating was modeled using the radiation element method by ray emission model (REM2). In order to validate the calculated results, the transmittances of these coatings were measured by a spectrophotometer. A UV barrier coating with a low UV transmittance and high VIS transmittance could be achieved. The calculated transmittance showed a similar spectral tendency with the measured one. The use of appropriate particles with optimum size, coating thickness and volume fraction will result in effective UV barrier coatings. UV barrier coatings can be achieved by the application of optical engineering.

An accelerated exposure and testing apparatus for building joint sealants

NASA Astrophysics Data System (ADS)

White, C. C.; Hunston, D. L.; Tan, K. T.; Hettenhouser, J.; Garver, J. D.

2013-09-01

The design, fabrication, and implementation of a computer-controlled exposure and testing apparatus for building joint sealants are described in this paper. This apparatus is unique in its ability to independently control and monitor temperature, relative humidity, ultraviolet (UV) radiation, and mechanical deformation. Each of these environmental factors can be controlled precisely over a wide range of conditions during periods of a month or more. Moreover, as controlled mechanical deformations can be generated, in situ mechanical characterization tests can be performed without removing specimens from the chamber. Temperature and humidity were controlled during our experiments via a precision temperature regulator and proportional mixing of dry and moisture-saturated air; while highly uniform UV radiation was attained by attaching the chamber to an integrating sphere-based radiation source. A computer-controlled stepper motor and a transmission system were used to provide precise movement control. The reliability and effectiveness of the apparatus were demonstrated on a model sealant material. The results clearly show that this apparatus provides an excellent platform to study the long-term durability of building joint sealants.

Rise and Fall: Poly(phenyl vinyl ketone) Photopolymerization and Photodegradation under Visible and UV Radiation.

PubMed

Reeves, Jennifer A; Allegrezza, Michael L; Konkolewicz, Dominik

2017-07-01

Vinyl ketone polymers, including phenyl vinyl ketone (PVK), are an important class of polymers due to their ability to degrade upon irradiation with ultraviolet light which makes them useful for a variety of applications. However, traditional radical methods for synthesizing PVK polymers give rise to poor control or are unable to produce block copolymers. This work uses reversible addition-fragmentation chain transfer polymerization (RAFT) and photochemistry to polymerize PVK. When visible blue radiation of 440 ± 10 nm is used as the light source for the photopolymerization, rapid polymerization and well-defined polymers are created. This RAFT method uses PVK as both monomer and radical initiator, exciting the PVK mono-mer by 440 ± 10 nm irradiation to avoid the use of an additional radical initiator. Once the poly-mer is synthesized, it is stable against degradation by blue light (440 ± 10 nm), but upon exposure to ultraviolet (UV) radiation (310 ± 20 nm) significant decrease in molecular weight is observed. The degradation is observed for all poly(PVK) materials synthesized. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An accelerated exposure and testing apparatus for building joint sealants.

PubMed

White, C C; Hunston, D L; Tan, K T; Hettenhouser, J; Garver, J D

2013-09-01

The design, fabrication, and implementation of a computer-controlled exposure and testing apparatus for building joint sealants are described in this paper. This apparatus is unique in its ability to independently control and monitor temperature, relative humidity, ultraviolet (UV) radiation, and mechanical deformation. Each of these environmental factors can be controlled precisely over a wide range of conditions during periods of a month or more. Moreover, as controlled mechanical deformations can be generated, in situ mechanical characterization tests can be performed without removing specimens from the chamber. Temperature and humidity were controlled during our experiments via a precision temperature regulator and proportional mixing of dry and moisture-saturated air; while highly uniform UV radiation was attained by attaching the chamber to an integrating sphere-based radiation source. A computer-controlled stepper motor and a transmission system were used to provide precise movement control. The reliability and effectiveness of the apparatus were demonstrated on a model sealant material. The results clearly show that this apparatus provides an excellent platform to study the long-term durability of building joint sealants.

Evaluation of phototoxic properties of fragrances.

PubMed

Placzek, Marianne; Frömel, Wolfgang; Eberlein, Bernadette; Gilbertz, Klaus-Peter; Przybilla, Bernhard

2007-01-01

Fragrances are widely used in topical formulations and can cause photoallergic or phototoxic reactions. To identify phototoxic effects, 43 fragrances were evaluated in vitro with a photohaemolysis test using suspensions of human erythrocytes exposed to radiation sources rich in ultraviolet (UV) A or B in the presence of the test compounds. Haemolysis was measured by reading the absorbance values, and photohaemolysis was calculated as a percentage of total haemolysis. Oakmoss caused photohaemolysis of up to 100% with radiation rich in UVA and up to 26% with radiation rich in UVB. Moderate UVA-induced haemolysis (5-11%) was found with benzyl alcohol, bergamot oil, costus root oil, lime oil, orange oil, alpha-amyl cinnamic aldehyde and laurel leaf oil. Moderate UVB-induced haemolysis was induced by hydroxy citronellal, cinnamic alcohol, cinnamic aldehyde, alpha-amyl cinnamic aldehyde and laurel leaf oil. The phototoxic effects depended on the concentration of the compounds and the UV doses administered. We conclude that some, but not all, fragrances exert phototoxic effects in vitro. Assessment of the correlation of the clinical effects of these findings could lead to improved protection of the skin from noxious compounds.

Effects of enhanced ultraviolet-B radiation, water deficit, and their combination on UV-absorbing compounds and osmotic adjustment substances in two different moss species.

PubMed

Hui, Rong; Zhao, Ruiming; Song, Guang; Li, Yixuan; Zhao, Yang; Wang, Yanli

2018-05-01

A simulation experiment was conducted to explore the influence of enhanced ultraviolet-B (UV-B) radiation, water deficit, and their combination on UV-absorbing compounds and osmotic adjustment substances of mosses Bryum argenteum and Didymodon vinealis isolated from biological soil crusts (BSCs) growing in a revegetated area of the Tengger Desert, China. Four levels of UV-B radiation and two gradients of water regime were employed. Compared with their controls, amounts of total flavonoids, chlorophyll, carotenoids, soluble sugars, and soluble proteins significantly decreased (p < 0.05), but proline content significantly increased (p < 0.05), when exposed to either enhanced UV-B or water deficit. The negative effects of enhanced UV-B were alleviated when water deficit was applied. There were increases in UV-absorbing compounds and osmotic adjustment substances when exposed to a combination of enhanced UV-B and water deficit compared with single stresses, except for the proline content in D. vinealis. In addition, our results also indicated interspecific differences in response to enhanced UV-B, water deficit, and their combination. Compared with B. argenteum, D. vinealis was more resistant to enhanced UV-B and water deficit singly and in combination. These results suggest that the damage of enhanced UV-B on both species might be alleviated by water deficit. This alleviation is important for understanding the response of BSCs to UV-B radiation in future global climate change. This also provides novel insights into assessment damages of UV-B to BSC stability in arid and semiarid regions.

Protective effect of cerium ion against ultraviolet B radiation-induced water stress in soybean seedlings.

PubMed

Mao, Chun Xia; Chen, Min Min; Wang, Lei; Zou, Hua; Liang, Chan Juan; Wang, Li Hong; Zhou, Qing

2012-06-01

Effects of cerium ion (Ce(III)) on water relations of soybean seedlings (Glycine max L.) under ultraviolet B radiation (UV-B, 280-320 nm) stress were investigated under laboratory conditions. UV-B radiation not only affected the contents of two osmolytes (proline, soluble sugar) in soybean seedlings, but also inhibited the transpiration in soybean seedlings by decreasing the stomatal density and conductance. The two effects caused the inhibition in the osmotic and metabolic absorption of water, which decreased the water content and the free water/bound water ratio. Obviously, UV-B radiation led to water stress, causing the decrease in the photosynthesis in soybean seedlings. The pretreatment with 20 mg L(-1) Ce(III) could alleviate UV-B-induced water stress by regulating the osmotic and metabolic absorption of water in soybean seedlings. The alleviated effect caused the increase in the photosynthesis and the growth of soybean seedlings. It is one of the protective effect mechanisms of Ce(III) against the UV-B radiation-induced damage to plants.

Influence of UV radiation and nitrosamines on the induction of mycotoxins synthesis by nontoxigenic moulds isolated from feed samples.

PubMed

Aziz, Nagy H; Smyk, B

2002-04-01

The effects of UV radiation and nitrosamines on the induction of mycotoxin biosynthesis by some nontoxigenic moulds isolated from feed samples collected from Egypt and Poland was investigated. Nontoxigenic strains of Aspergillus flavus P-63, A. niger EN-200 and A. ochraceus P-157 synthesized mycotoxins (aflatoxins and ochratoxin, A) after exposure to near UV radiation for 120-210 min. Nitrosamines (DMNA and DENA) at 30 up to 1000 ppm induced the synthesis of aflatoxins by nontoxigenic species of A. flavus ES-255 and P-63 and A. niger EN 200. Near-UV radiation and nitrosamines had no influence on the induction of mycotoxin synthesis by Penicillium and Fusarium isolates. All nontoxigenic strains of Aspergilli which synthesized aflatoxins in the presence of 1000 ppm nitrosamines, also synthesized continuously aflatoxins during the next fifteen generations. Near-UV radiation and nitrosamines had a mutagenic effect on the induction of mycotoxins synthesis by nontoxigenic moulds.

Survival of Staphylococcus aureus exposed to UV radiation on the surface of ceramic tiles coated with TiO2.

PubMed

Szczawiński, J; Tomaszewski, H; Jackowska-Tracz, A; Szczawińska, M E

2011-01-01

The aim of this study was to determine and compare the antimicrobial activity of UV radiation of wavelength 253.7 nm (used in typical germicidal lamps) against Staphylococcus aureus on the surfaces of conventionally produced white ceramic wall tiles (matt and shiny) and the same tiles coated with TiO2 using three different methods: RF diode sputtering, atmospheric pressure chemical vapour deposition (APCVD) and spray pyrolysis deposition (SPD). Results clearly indicate that the bactericidal action of UV radiation is much stronger on the surfaces of tiles coated with TiO2 than on the tiles uncovered. The strongest bactericidal effect of UV radiation was found for film prepared by APCVD. Results of experiments for shiny and matt tiles did not differ statistically. The use of ceramic wall tiles coated with TiO2 films in hospitals, veterinary clinics, laboratories, food processing plants and other places where UV radiation is applied for disinfection should greatly improve the efficiency of this treatment.

Automating Microbial Directed Evolution For Bioengineering Applications

NASA Astrophysics Data System (ADS)

Lee, A.; Demachkie, I. S.; Sardesh, N.; Arismendi, D.; Ouandji, C.; Wang, J.; Blaich, J.; Gentry, D.

2016-12-01

From a micro-biology perspective, directed evolution is a technique that uses controlled environmental pressures to select for a desired phenotype. Directed evolution has the distinct advantage over rational design of not needing extensive knowledge of the genome or pathways associated with a microorganism to induce phenotypes. However, there are currently limitations to the applicability of this technique including being time-consuming, error-prone, and dependent on existing assays that may lack selectivity for the given phenotype. The AADEC (Autonomous Adaptive Directed Evolution Chamber) system is a proof-of-concept instrument to automate and improve the technique such that directed evolution can be used more effectively as a general bioengineering tool. A series of tests using the automated system and comparable by-hand survival assay measurements have been carried out using UV-C radiation and Escherichia coli cultures in order to demonstrate the advantages of the AADEC versus traditional implementations of directed evolution such as random mutagenesis. AADEC uses UV-C exposure as both a source of environmental stress and mutagenesis, so in order to evaluate the UV-C tolerance obtained from the cultures, a manual UV-C exposure survival assay was developed alongside the device to compare the survival fractions at a fixed dosage. This survival assay involves exposing E.coli to UV-C radiation using a custom-designed exposure hood to control the flux and dose. Surviving cells are counted then transferred to the next iteration and so on for several iterations to calculate the survival fractions for each exposure iteration. This survival assay primarily serves as a baseline for the AADEC device, allowing quantification of the differences between the AADEC system over the manual approach. The primary data of comparison is survival fractions; this is obtained by optical density and plate counts in the manual assay and by optical density growth curve fits pre- and post-exposure in the automated case. This data can then be compiled to calculate trends over the iterations to characterize increasing UV-C resistance of the E.coli strains. The observed trends are statistically indistinguishable through several iterations from both sources.

Survival of prototype strains of somatic coliphage families in environmental waters and when exposed to UV low-pressure monochromatic radiation or heat.

PubMed

Lee, Hee Suk; Sobsey, Mark D

2011-06-01

The potential use of specific somatic coliphage taxonomic groups as viral indicators based on their persistence and prevalence in water was investigated. Representative type strains of the 4 major somatic coliphage taxonomic groups were seeded into reagent water and an ambient surface water source of drinking water and the survival of the added phages was measured over 90 days at temperatures of 23-25 and 4 °C. Microviridae (type strain PhiX174), Siphoviridae (type strain Lambda), and Myoviridae (type strain T4) viruses were the most persistent in water at the temperatures tested. The Microviridae (type strain PhiX174) and the Siphoviridae (type strain Lambda) were the most resistant viruses to UV radiation and the Myoviridae (type strain T4) and the Microviridae (type strain PhiX174) were the most resistant viruses to heat. Based on their greater persistence in water over time and their relative resistance to heat and/or UV radiation, the Myoviridae (type strain T4), the Microviridae (type strain PhiX174), and the Siphoviridae (type strain Lambda) were the preferred candidate somatic coliphages as fecal indicator viruses in water, with the Microviridae (type strain PhiX174) the most resistant to these conditions overall. Copyright © 2011 Elsevier Ltd. All rights reserved.

Preharvest UV-C radiation influences physiological, biochemical, and transcriptional changes in strawberry cv. Camarosa.

PubMed

de Oliveira, Isadora Rubin; Crizel, Giseli Rodrigues; Severo, Joseana; Renard, Catherine M G C; Chaves, Fabio Clasen; Rombaldi, Cesar Valmor

2016-11-01

Ultraviolet C (UV-C) radiation is known for preventing fungal decay and enhancing phytochemical content in fruit when applied postharvest. However, limited knowledge is available regarding fruit responses to preharvest application of UV-C radiation. Thus, the effects of UV-C radiation on photosynthetic efficiency, dry matter accumulation and partitioning, fruit yield and decay, phytochemical content, and relative transcript accumulation of genes associated with these metabolic pathways were monitored in strawberry (Fragaria x ananassa Duch.) cv. Camarosa. A reduction in photosynthetic efficiency was followed by a decrease in light harvesting complex LhcIIb-1 mRNA accumulation as well as a decrease in yield per plant. Phenylalanine ammonia lyase activity, phenolic, anthocyanin, and L-ascorbic acid contents were higher in UV-C treated fruit. In addition, preharvest UV-C treatment reduced microorganism incidence in the greenhouse and on the fruit surface, increased the accumulation of β-1,3-Gluc and PR-1 mRNA, and prevented fruit decay. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Arsenic oxidation by UV radiation combined with hydrogen peroxide.

PubMed

Sorlini, S; Gialdini, F; Stefan, M

2010-01-01

Arsenic is a widespread contaminant in the environment around the world. The most abundant species of arsenic in groundwater are arsenite [As(III)] and arsenate [As(V)]. Several arsenic removal processes can reach good removal yields only if arsenic is present as As(V). For this reason it is often necessary to proceed with a preliminary oxidation of As(III) to As(V) prior to the removal technology. Several studies have focused on arsenic oxidation with conventional reagents and advanced oxidation processes. In the present study the arsenic oxidation was evaluated using hydrogen peroxide, UV radiation and their combination in distilled and in real groundwater samples. Hydrogen peroxide and UV radiation alone are not effective at the arsenic oxidation. Good arsenic oxidation yields can be reached in presence of hydrogen peroxide combined with a high UV radiation dose (2,000 mJ/cm(2)). The quantum efficiencies for As(III) oxidation were calculated for both the UV photolysis and the UV/H(2)O(2) processes.

UNLAMINATED GAFCHROMIC EBT3 FILM FOR ULTRAVIOLET RADIATION MONITORING.

PubMed

Welch, David; Randers-Pehrson, Gerhard; Spotnitz, Henry M; Brenner, David J

2017-11-01

Measurement of ultraviolet (UV) radiation is important for human health, especially with the expanded usage of short wavelength UV for sterilization purposes. This work examines unlaminated Gafchromic EBT3 film for UV radiation monitoring. The authors exposed the film to select wavelengths in the UV spectrum, ranging from 207 to 328 nm, and measured the change in optical density. The response of the film is wavelength dependent, and of the wavelengths tested, the film was most sensitive to 254 nm light, with measurable values as low as 10 µJ/cm2. The film shows a dose-dependent response that extends over more than four orders of magnitude. The response of the film to short wavelength UV is comparable to the daily safe exposure limits for humans, thus making it valuable as a tool for passive UV radiation monitoring. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Photoenhanced toxicity of a carbamate insecticide to early life stage anuran amphibians

USGS Publications Warehouse

Zaga, A.; Little, E.E.; Rabeni, C.F.; Ellersieck, Mark R.

1998-01-01

Aican clawed frog (Xenopus laevis) and gray tree frog (Hyla versicolor) embryos and tadpoles were exposed to sublethal levels of carbaryl, a broad-spectrum insecticide, and ultraviolet radiation to determine interactive and sublethal effects. Ultraviolet intensity (UV-B [285–320 nm] plus UV-A [321–400 nm]) was controlled with various types of plastic filters and quantified with a scanning spectroradiometer. Significant differences in swimming activity and mortality of both species were evident during the 96-h experiments. Ultraviolet-B radiation alone and carbaryl in the presence of UV-B significantly decreased swimming activity of both species. As little as 1.5% intensity of ambient solar UV-B radiation photoactivated carbaryl. Toxicity of 7.5 mg/L carbaryl increased by 10-fold in the presence of UV-B in all species and life stages tested. Our results indicate that photoenhancement by solar UV-B radiation should be considered when evaluating the toxicity of contaminants to amphibians and other organisms.

[Analysis of the cumulative solar ultraviolet radiation in Mexico].

PubMed

Castanedo-Cázares, Juan Pablo; Torres-Álvarez, Bertha; Portales-González, Bárbara; Martínez-Rosales, Karla; Hernández-Blanco, Diana

2016-01-01

The incidence of skin cancer has increased in Mexico in recent years. Ultraviolet radiation is the main risk factor associated. Due to the need to develop strategies to prevent skin cancer, the aim of the study was to estimate the UV intensity in several representative regions of Mexico, the average annual UV dose of these populations, and the potential benefit of applying sunscreen at different ages. The intensity of UV radiation was quantified by remote and terrestrial radiometry. The dose of UV exposure was measured in minimal erythema doses using validated models for face and arms. The benefit of using a sunscreen was calculated with the use of a sunscreen with SPF 15 from birth to age 70. The UV radiation is lower in December and greater in the period from May to July. The region with a lower annual dose is Tijuana; and the higher annual dose is in the Mexico City area. The annual difference between these regions was 58 %. Through life, a low SPF sunscreen can reduce up to 66 % of the received UV dose. The geographical location is a risk factor for accumulation of UV radiation in Mexico. Since childhood, people receive high amounts of it; however, most of this dose can be reduced using any commercially available sunscreen, if applied strategically.

Responses of Crepis japonica induced by supplemental blue light and UV-A radiation.

PubMed

Constantino, L F da S; Nascimento, L B Dos S; Casanova, L M; Moreira, N Dos S; Menezes, E A; Esteves, R L; Costa, S S; Tavares, E S

2017-02-15

Crepis japonica (L.) D.C. (Asteraceae), a weed with antioxidant, antiallergenic, antiviral and antitumor properties displays both medicinal properties and nutritional value. This study aims to assess the effects of a supplementation of blue light and UV-A radiation on the growth, leaf anatomical structure and phenolic profile of the aerial parts of Crepis japonica. Plants were grown under two light treatments: W (control - white light), W + B (white light supplemented with blue light) and W + UV-A (white light supplemented with UV-A radiation). We recorded the length, width, and weight of fresh and dry leaves, the thickness of the epidermis and mesophyll, and stomata density. The phenolic profiles of the aqueous extracts of the aerial parts were analyzed by HPLC-DAD. There was an increase in the leaf size, stomatal density, and phenolic production, and a thickening of the mesophyll and epidermis. UV-A radiation increased the phenolic production more than blue light. Blue light and UV-A radiation both improved the production of caffeic acid by about 6 and 3 times, respectively, in comparison to control. This compound was first reported as a constituent of the extract from the aerial parts together with caftaric acid. UV-A also promoted the production of chlorogenic acid (about 1.5 times in comparison to the control). We observed that the morphological and chemical parameters of C. japonica are modified in response to blue light and UV-A radiation, which can be used as tools in the cultivation of this species in order to improve its medicinal properties and nutritional value.

Hypersensitivity of skin fibroblasts from basal cell nevus syndrome patients to killing by ultraviolet B but not by ultraviolet C radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Applegate, L.A.; Goldberg, L.H.; Ley, R.D.

Basal cell nevus syndrome (BCNS) is an autosomal dominant genetic disorder in which the afflicted individuals are extremely susceptible to sunlight-induced skin cancers, particularly basal cell carcinomas. However, the cellular and molecular basis for BCNS is unknown. To ascertain whether there is any relationship between genetic predisposition to skin cancer and increased sensitivity of somatic cells from BCNS patients to killing by UV radiation, we exposed skin fibroblasts established from unexposed skin biopsies of several BCNS and age- and sex-matched normal individuals to either UV-B (280-320 nm) or UV-C (254 nm) radiation and determined their survival. The results indicated thatmore » skin fibroblasts from BCNS patients were hypersensitive to killing by UV-B but not UV-C radiation as compared to skin fibroblasts from normal individuals. DNA repair studies indicated that the increased sensitivity of BCNS skin fibroblasts to killing by UV-B radiation was not due to a defect in the excision repair of pyrimidine dimers. These results indicate that there is an association between hypersensitivity of somatic cells to killing by UV-B radiation and the genetic predisposition to skin cancer in BCNS patients. In addition, these results suggest that DNA lesions (and repair processes) other than the pyrimidine dimer are also involved in the pathogenesis of sunlight-induced skin cancers in BCNS patients. More important, the UV-B sensitivity assay described here may be used as a diagnostic tool to identify presymptomatic individuals with BCNS.« less

Survival of microorganisms in space protected by meteorite material: results of the experiment 'EXOBIOLOGIE' of the PERSEUS mission.

PubMed

Rettberg, P; Eschweiler, U; Strauch, K; Reitz, G; Horneck, G; Wanke, H; Brack, A; Barbier, B

2002-01-01

During the early evolution of life on Earth, before the formation of a protective ozone layer in the atmosphere, high intensities of solar UV radiation of short wavelengths could reach the surface of the Earth. Today the full spectrum of solar UV radiation is only experienced in space, where other important space parameters influence survival and genetic stability additionally, like vacuum, cosmic radiation, temperature extremes, microgravity. To reach a better understanding of the processes leading to the origin, evolution and distribution of life we have performed space experiments with microorganisms. The ability of resistant life forms like bacterial spores to survive high doses of extraterrestrial solar UV alone or in combination with other space parameters, e.g. vacuum, was investigated. Extraterrestrial solar UV was found to have a thousand times higher biological effectiveness than UV radiation filtered by stratospheric ozone concentrations found today on Earth. The protective effects of anorganic substances like artificial or real meteorites were determined on the MIR station. In the experiment EXOBIOLOGIE of the French PERSEUS mission (1999) it was found that very thin layers of anorganic material did not protect spores against the deleterious effects of energy-rich UV radiation in space to the expected amount, but that layers of UV radiation inactivated spores serve as a UV-shield by themselves, so that a hypothetical interplanetary transfer of life by the transport of microorganisms inside rocks through the solar system cannot be excluded, but requires the shielding of a substantial mass of anorganic substances. c2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

Effect of UV-A radiation as an environmental stress on the development, longevity, and reproduction of the oriental armyworm, Mythimna separata (Lepidoptera: Noctuidae).

PubMed

Ali, Arif; Rashid, Muhammad Adnan; Huang, Qiu Ying; Lei, Chao-Liang

2016-09-01

The ultraviolet light (UV-A) range of 320-400 nm is widely used as light trap for insect pests. Present investigation was aimed to determine the effect of UV light-A radiation on development, adult longevity, reproduction, and development of F1 generation of Mythimna separata. Our results revealed that the mortality of the second instar larvae was higher than the third and fourth instar larvae after UV-A radiation. As the time of UV-A irradiation for pupae prolonged, the rate of adult emergence reduced. Along with the extension of radiation time decreased the longevity of adult females and males. However, the radiation exposure of 1 and 4 h/day increased fecundity of female adults, and a significant difference was observed in a 1 h/day group. The oviposition rates of female adults in all the treatments were significantly higher than the control. In addition, UV-A radiation treatments resulted in declined cumulative survival of F1 immature stages (eggs, larvae, and pupae). After exposure time of 4 and 7 h/day, the developmental periods of F1 larvae increased significantly, but no significant effects on F1 pupal period were recorded.

Integration and scaling of UV-B radiation effects on plants: from molecular interactions to whole plant responses.

PubMed

Suchar, Vasile Alexandru; Robberecht, Ronald

2016-07-01

A process based model integrating the effects of UV-B radiation to molecular level processes and their consequences to whole plant growth and development was developed from key parameters in the published literature. Model simulations showed that UV-B radiation induced changes in plant metabolic and/or photosynthesis rates can result in plant growth inhibitions. The costs of effective epidermal UV-B radiation absorptive compounds did not result in any significant changes in plant growth, but any associated metabolic costs effectively reduced the potential plant biomass. The model showed significant interactions between UV-B radiation effects and temperature and any factor leading to inhibition of photosynthetic production or plant growth during the midday, but the effects were not cumulative for all factors. Vegetative growth were significantly delayed in species that do not exhibit reproductive cycles during a growing season, but vegetative growth and reproductive yield in species completing their life cycle in one growing season did not appear to be delayed more than 2-5 days, probably within the natural variability of the life cycles for many species. This is the first model to integrate the effects of increased UV-B radiation through molecular level processes and their consequences to whole plant growth and development.

Survival of thermophilic and hyperthermophilic microorganisms after exposure to UV-C, ionizing radiation and desiccation.

PubMed

Beblo, Kristina; Douki, Thierry; Schmalz, Gottfried; Rachel, Reinhard; Wirth, Reinhard; Huber, Harald; Reitz, Günther; Rettberg, Petra

2011-11-01

In this study, we investigated the ability of several (hyper-) thermophilic Archaea and phylogenetically deep-branching thermophilic Bacteria to survive high fluences of monochromatic UV-C (254 nm) and high doses of ionizing radiation, respectively. Nine out of fourteen tested microorganisms showed a surprisingly high tolerance against ionizing radiation, and two species (Aquifex pyrophilus and Ignicoccus hospitalis) were even able to survive 20 kGy. Therefore, these species had a comparable survivability after exposure to ionizing radiation such as Deinococcus radiodurans. In contrast, there was nearly no difference in survival of the tested strains after exposure to UV-C under anoxic conditions. If the cells had been dried in advance of UV-C irradiation, they were more sensitive to UV-C radiation compared with cells irradiated in liquid suspension; this effect could be reversed by the addition of protective material like sulfidic ores before irradiation. By exposure to UV-C, photoproducts were formed in the DNA of irradiated Archaea and Bacteria. The distribution of the main photoproducts was species specific, but the amount of the photoproducts was only partly dependent on the applied fluence. Overall, our results show that tolerance to radiation seems to be a common phenomenon among thermophilic and hyperthermophilic microorganisms.

Responses of photosynthetic properties and chloroplast ultrastructure of two moss crusts from a desert biological soil crust to supplementary UV-B radiation

NASA Astrophysics Data System (ADS)

Hui, Rong; Li, Xinrong; Zhao, Yang; Pan, Yanxia

2016-04-01

Our understanding of plant responses to supplementary ultraviolet-B (UV-B) radiation due to stratospheric ozone depletion has improved over recent decades. However, research on biological soil crusts (BSCs) is scarce and it remains controversial. Laboratory studies were conducted to investigate the influence of UV-B radiation on the Bryum argenteum and Didymodon vinealis isolated from BSCs, which are both dominant species in moss crusts found within patches of shrubs and herbs in the Tengger Desert of northern China. The aim of the current work was to evaluate whether supplementary UV-B radiation affected photosynthetic properties and chloroplast ultrastructure of two moss crusts and whether response differences were observed between the crusts. Four levels of UV-B radiation of 2.75 (control), 3.08, 3.25, and 3.41 W m-2 was achieved using fluorescence tube systems for 10 days, simulating 0, 6, 9, and 12% of stratospheric ozone at the latitude of Shapotou, respectively. We measured photosynthetic apparatus as assessed by chlorophyll a fluorescence parameters, photosynthetic pigment contents, and observations of chloroplast ultrastructure. Additionally, soluble proteins and UV-B absorbing compounds were simultaneously investigated. The results of this study showed that chlorophyll a fluorescence parameters (i.e., the maximal quantum yield of PSII photochemistry, the effective quantum yield of PSII photochemistry, and photochemical quenching coefficient), photosynthetic pigment contents, soluble protein contents, total flavonoid contents and the ultrastructure were negatively influenced by elevated UV-B radiation and the degree of detrimental effects significantly increased with the intensity of UV-B radiation. Moreover, results demonstrated that the negative effects on photosynthesis and chloroplast ultrastructure were more serious in B. argenteum than that in D. vinealis. These results may not only provide a potential mechanism for supplemental UV-B effects on photosynthesis of moss crusts, but also establish a theoretical basis for further studies of adaptation and response mechanisms of desert ecosystems under further ozone depletion.

Effects of photoperiod regimes and ultraviolet-C radiations on biosynthesis of industrially important lignans and neolignans in cell cultures of Linum usitatissimum L. (Flax).

PubMed

Anjum, Sumaira; Abbasi, Bilal Haider; Doussot, Joël; Favre-Réguillon, Alain; Hano, Christophe

2017-02-01

Lignans and neolignans are principal bioactive components of Linum usitatissimum L. (Flax), having multiple pharmacological activities. In present study, we are reporting an authoritative abiotic elicitation strategy of photoperiod regimes along with UV-C radiations. Cell cultures were grown in different photoperiod regimes (24h-dark, 24h-light and 16L/8D h photoperiod) either alone or in combination with various doses (1.8-10.8kJ/m 2 ) of ultraviolet-C (UV-C) radiations. Secoisolariciresinol diglucoside (SDG), lariciresinol diglucoside (LDG), dehydrodiconiferyl alcohol glucoside (DCG), and guaiacylglycerol-β-coniferyl alcohol ether glucoside (GGCG) were quantified by using reverse phase-high performance liquid chromatography (RP-HPLC). Results showed that the cultures exposed to UV-C radiations, accumulated higher levels of lignans, neolignans and other biochemical markers than cultures grown under different photoperiod regimes. 3.6kJ/m 2 dose of UV-C radiations resulted in 1.86-fold (7.1mg/g DW) increase in accumulation of SDG, 2.25-fold (21.6mg/g DW) in LDG, and 1.33-fold (9.2mg/g DW) in GGCG in cell cultures grown under UV+photoperiod than their respective controls. Furthermore, cell cultures grown under UV+dark showed 1.36-fold (60.0mg/g DW) increase in accumulation of DCG in response to 1.8kJ/m 2 dose of UV-C radiations. Smilar trends were observed in productivity of SDG, LDG and GGCG. Additionally, 3.6kJ/m 2 dose of UV-C radiations also resulted in 2.82-fold (195.65mg/l) increase in total phenolic production, 2.94-fold (98.9mg/l) in total flavonoid production and 1.04-fold (95%) in antioxidant activity of cell cultures grown under UV+photoperiod. These findings open new dimensions for feasible production of biologically active lignans and neolignans by Flax cell cultures. Copyright © 2017 Elsevier B.V. All rights reserved.

Prebiotic chemistry: chemical evolution of organics on the primitive Earth under simulated prebiotic conditions.

PubMed

Dondi, Daniele; Merli, Daniele; Pretali, Luca; Fagnoni, Maurizio; Albini, Angelo; Serpone, Nick

2007-11-01

A series of prebiotic mixtures of simple molecules, sources of C, H, N, and O, were examined under conditions that may have prevailed during the Hadean eon (4.6-3.8 billion years), namely an oxygen-free atmosphere and a significant UV radiation flux over a large wavelength range due to the absence of an ozone layer. Mixtures contained a C source (methanol, acetone or other ketones), a N source (ammonia or methylamine), and an O source (water) at various molar ratios of C : H : N : O. When subjected to UV light or heated for periods of 7 to 45 days under an argon atmosphere, they yielded a narrow product distribution of a few principal compounds. Different initial conditions produced different distributions. The nature of the products was ascertained by gas chromatographic-mass spectral analysis (GC-MS). UVC irradiation of an aqueous methanol-ammonia-water prebiotic mixture for 14 days under low UV dose (6 x 10(-2) Einstein) produced methylisourea, hexamethylenetetramine (HMT), methyl-HMT and hydroxy-HMT, whereas under high UV dose (45 days; 1.9 x 10(-1) Einstein) yielded only HMT. By contrast, the prebiotic mixture composed of acetone-ammonia-water produced five principal species with acetamide as the major component; thermally the same mixture produced a different product distribution of four principal species. UVC irradiation of the CH(3)CN-NH(3)-H(2)O prebiotic mixture for 7 days gave mostly trimethyl-s-triazine, whereas in the presence of two metal oxides (TiO(2) or Fe(2)O(3)) also produced some HMT; the thermal process yielded only acetamide.

Degradation of Methyl Orange and Congo Red dyes by using TiO2 nanoparticles activated by the solar and the solar-like radiation.

PubMed

Ljubas, Davor; Smoljanić, Goran; Juretić, Hrvoje

2015-09-15

In this study we used TiO2 nanoparticles as semiconductor photocatalysts for the degradation of Methyl Orange (MO) and Congo Red (CR) dyes in an aqueous solution. Since TiO2 particles become photocatalytically active by UV radiation, two sources of UV-A radiation were used - natural solar radiation which contains 3-5% UV-A and artificial, solar-like radiation, created by using a lamp. The optimal doses of TiO2 of 500 mg/L for the CR and 1500 mg/L for the MO degradation were determined in experiments with the lamp and were also used in degradation experiments with natural solar light. The efficiency of each process was determined by measuring the absorbance at two visible wavelengths, 466 nm for MO and 498 nm for CR, and the total organic carbon (TOC), i.e. decolorization and mineralization, respectively. In both cases, considerable potential for the degradation of CR and MO was observed - total decolorization of the solution was achieved within 30-60 min, while the TOC removal was in the range 60-90%. CR and MO solutions irradiated without TiO2 nanoparticles showed no observable changes in either decolorization or mineralization. Three different commercially available TiO2 nanoparticles were used: pure-phase anatase, pure-phase rutile, and mixed-phase preparation named Degussa P25. In terms of degradation kinetics, P25 TiO2 exhibited a photocatalytic activity superior to that of pure-phase anatase or rutile. The electric energy consumption per gram of removed TOC was determined. For nearly the same degradation effect, the consumption in the natural solar radiation experiment was more than 60 times lower than in the artificial solar-like radiation experiment. Copyright © 2015 Elsevier Ltd. All rights reserved.

Constraints on the Early Terrestrial Surface UV Environment Relevant to Prebiotic Chemistry.

PubMed

Ranjan, Sukrit; Sasselov, Dimitar D

2017-03-01

The UV environment is a key boundary condition to abiogenesis. However, considerable uncertainty exists as to planetary conditions and hence surface UV at abiogenesis. Here, we present two-stream multilayer clear-sky calculations of the UV surface radiance on Earth at 3.9 Ga to constrain the UV surface fluence as a function of albedo, solar zenith angle (SZA), and atmospheric composition. Variation in albedo and latitude (through SZA) can affect maximum photoreaction rates by a factor of >10.4; for the same atmosphere, photoreactions can proceed an order of magnitude faster at the equator of a snowball Earth than at the poles of a warmer world. Hence, surface conditions are important considerations when computing prebiotic UV fluences. For climatically reasonable levels of CO 2 , fluence shortward of 189 nm is screened out, meaning that prebiotic chemistry is robustly shielded from variations in UV fluence due to solar flares or variability. Strong shielding from CO 2 also means that the UV surface fluence is insensitive to plausible levels of CH 4 , O 2 , and O 3 . At scattering wavelengths, UV fluence drops off comparatively slowly with increasing CO 2 levels. However, if SO 2 and/or H 2 S can build up to the ≥1-100 ppm level as hypothesized by some workers, then they can dramatically suppress surface fluence and hence prebiotic photoprocesses. H 2 O is a robust UV shield for λ < 198 nm. This means that regardless of the levels of other atmospheric gases, fluence ≲198 nm is only available for cold, dry atmospheres, meaning sources with emission ≲198 (e.g., ArF excimer lasers) can only be used in simulations of cold environments with low abundance of volcanogenic gases. On the other hand, fluence at 254 nm is unshielded by H 2 O and is available across a broad range of [Formula: see text], meaning that mercury lamps are suitable for initial studies regardless of the uncertainty in primordial H 2 O and CO 2 levels. Key Words: Radiative transfer-Origin of life-Planetary environments-UV radiation-Prebiotic chemistry. Astrobiology 17, 169-204.

IUE observations of the hot components in two symbiotic stars

NASA Technical Reports Server (NTRS)

Michalitsianos, A. G.; Hobbs, R. W.; Maran, S. P.; Kafatos, M.

1980-01-01

Recent IUE observations reveal striking differences in the UV spectra of two symbiotic stars, R Aqr and RW Hya. RW Hya is found to be an unexpectedly intense source of UV radiation. The measurements reported demonstrate the presence of a hot component in each star, supporting the view that each is a binary system with a luminous red primary and a hot, subluminous companion. In one case, the hot companion manifests itself by exciting a compact nebulosity; in the other case the continuous spectrum of the hot star is directly detected, while the continuum of nebulosity excited by the hot star is detected at longer wavelengths.

Effects of ultraviolet-B radiation on the growth, physiology and cannabinoid production of Cannabis sativa L

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lydon, J.

The concentration of cannabinoids in Cannabis sativa L. is correlated with high ultraviolet-B (UV-B) radiation environments. ..delta../sup 9/-Tetrahydrocannabinolic acid and cannabidiolic acid, both major secondary products of C. sativa, absorb UV-B radiation and may function as solar screens. The object of this study was to test the effects of UV-B radiation on the physiology and cannabinoid production of C. sativa. Drug and fiber-type C. sativa were irradiated with three levels of UV-B radiation for 40 days in greenhouse experiments. Physiological measurements on leaf tissues were made by infra-red gas analysis. Drug and fiber-type control plants had similar CO/sub 2/ assimilationmore » rates from 26 to 32/sup 0/C. Drug-type control plant had higher dark respiration rates and stomatal conductances than fiber-type control plants. The concentration of ..delta../sup 9/-THC, but not of other cannabinoids) in both vegetative and reproductive tissues increased with UV-B dose in drug-type plants. None of the cannabinoids in fiber-type plants were affected by UV-B radiation. The increased level of ..delta../sup 9/-THC found in leaves after irradiation may account for the physiological and morphological insensitivity to UV-B radiation in the drug-type plants. However, fiber plants showed no comparable change in the level of cannabidoil (CBD). Resin stripped form fresh fiber-type floral tissue by sonication was spotted on filter paper and irradiated continuously for 7 days. Cannabidiol (CBD) gradually decreased when irradiated but ..delta../sup 9/-THC and cannabichromene did not.« less

Effects of silicon application on diurnal variations of physiological properties of rice leaves of plants at the heading stage under elevated UV-B radiation

NASA Astrophysics Data System (ADS)

Lou, Yun-sheng; Wu, Lei; Lixuan, Ren; Meng, Yan; Shidi, Zhao; Huaiwei, Zhu; Yiwei, Zhang

2016-02-01

We investigated the effects of silicon (Si) application on diurnal variations of photosynthetic and transpiration physiological parameters in potted rice ( Oryza sativa L. cv Nanjing 45) at the heading stage. The plants were subjected to two UV-B radiation levels, i.e., reference UV-B (A, ambient, 12.0 kJ m-2 day-1) and elevated UV-B radiation (E, a 20 % higher dose of UV-B than the reference, 14.4 kJ m-2 day-1), and four Si application levels, i.e., Si0 (no silicon supplementation, 0 kg SiO2 ha-1), Si1 (sodium silicate, 100 kg SiO2 ha-1), Si2 (sodium silicate, 200 kg SiO2 ha-1), and Si3 (slag silicon fertilizer, 200 kg SiO2 ha-1). Compared with the reference, elevated UV-B radiation decreased the diurnal mean values of the net photosynthetic rate ( Pn), intercellular carbon dioxide (CO2) concentration ( Ci), transpiration rate ( Tr), stomatal conductivity ( Gs), and water use efficiency (WUE) by 11.3, 5.5, 10.4, 20.3, and 6.3 %, respectively, in plants not supplemented with silicon (Si0), and decreased the above parameters by 3.8-5.5, 0.7-4.8, 4.0-8.7, 7.4-20.2, and 0.7-5.9 %, respectively, in plants treated with silicon (Si1, Si2, and Si3), indicating that silicon application mitigates the negative effects of elevated UV-B radiation. Under elevated UV-B radiation, silicon application (Si1, Si2, and Si3) increased the diurnal mean values of Pn, Ci, Gs, and WUE by 16.9-28.0, 3.5-14.3, 16.8-38.7, and 29.0-51.2 %, respectively, but decreased Tr by 1.9-10.8 %, compared with plants not treated with silicon (E+Si0), indicating that silicon application mitigates the negative effects of elevated UV-B radiation by significantly increasing the P n, C i, G s, and WUE and decreasing the T r of rice. Evident differences existed in mitigating the depressive effects of elevated UV-B radiation on diurnal variations of physiological parameters among different silicon application treatments, exhibiting as Si3>Si2>Si1>Si0. In addition to recycling steel industrial wastes, the application of slag silicon fertilizer mitigates the negative effects of elevated UV-B radiation on photosynthesis and transpiration in rice.

Effects of silicon application on diurnal variations of physiological properties of rice leaves of plants at the heading stage under elevated UV-B radiation.

PubMed

Lou, Yun-sheng; Wu, Lei; Lixuan, Ren; Meng, Yan; Shidi, Zhao; Huaiwei, Zhu; Yiwei, Zhang

2016-02-01

We investigated the effects of silicon (Si) application on diurnal variations of photosynthetic and transpiration physiological parameters in potted rice (Oryza sativa L. cv Nanjing 45) at the heading stage. The plants were subjected to two UV-B radiation levels, i.e., reference UV-B (A, ambient, 12.0 kJ m(-2) day(-1)) and elevated UV-B radiation (E, a 20% higher dose of UV-B than the reference, 14.4 kJ m(-2) day(-1)), and four Si application levels, i.e., Si0 (no silicon supplementation, 0 kg SiO2 ha(-1)), Si1 (sodium silicate, 100 kg SiO2 ha(-1)), Si2 (sodium silicate, 200 kg SiO2 ha(-1)), and Si3 (slag silicon fertilizer, 200 kg SiO2 ha(-1)). Compared with the reference, elevated UV-B radiation decreased the diurnal mean values of the net photosynthetic rate (Pn), intercellular carbon dioxide (CO2) concentration (Ci), transpiration rate (Tr), stomatal conductivity (Gs), and water use efficiency (WUE) by 11.3, 5.5, 10.4, 20.3, and 6.3%, respectively, in plants not supplemented with silicon (Si0), and decreased the above parameters by 3.8-5.5, 0.7-4.8, 4.0-8.7, 7.4-20.2, and 0.7-5.9%, respectively, in plants treated with silicon (Si1, Si2, and Si3), indicating that silicon application mitigates the negative effects of elevated UV-B radiation. Under elevated UV-B radiation, silicon application (Si1, Si2, and Si3) increased the diurnal mean values of Pn, Ci, Gs, and WUE by 16.9-28.0, 3.5-14.3, 16.8-38.7, and 29.0-51.2%, respectively, but decreased Tr by 1.9-10.8%, compared with plants not treated with silicon (E+Si0), indicating that silicon application mitigates the negative effects of elevated UV-B radiation by significantly increasing the P n, C i, G s, and WUE and decreasing the T r of rice. Evident differences existed in mitigating the depressive effects of elevated UV-B radiation on diurnal variations of physiological parameters among different silicon application treatments, exhibiting as Si3>Si2>Si1>Si0. In addition to recycling steel industrial wastes, the application of slag silicon fertilizer mitigates the negative effects of elevated UV-B radiation on photosynthesis and transpiration in rice.

UV Radiation Activates Toll-Like Receptor 9 Expression in Primary Human Keratinocytes, an Event Inhibited by Human Papillomavirus 38 E6 and E7 Oncoproteins.

PubMed

Pacini, Laura; Ceraolo, Maria Grazia; Venuti, Assunta; Melita, Giusi; Hasan, Uzma A; Accardi, Rosita; Tommasino, Massimo

2017-10-01

Several lines of evidence indicate that cutaneous human papillomavirus (HPV) types belonging to the beta genus of the HPV phylogenetic tree synergize with UV radiation in the development of skin cancer. Accordingly, the E6 and E7 oncoproteins from some beta HPV types are able to deregulate pathways related to immune response and cellular transformation. Toll-like receptor 9 (TLR9), in addition to playing a role in innate immunity, has been shown to be involved in the cellular stress response. Using primary human keratinocytes as experimental models, we have shown that UV irradiation (and other cellular stresses) activates TLR9 expression. This event is closely linked to p53 activation. Silencing the expression of p53 or deleting its encoding gene affected the activation of TLR9 expression after UV irradiation. Using various strategies, we have also shown that the transcription factors p53 and c-Jun are recruited onto a specific region of the TLR9 promoter after UV irradiation. Importantly, the E6 and E7 oncoproteins from beta HPV38, by inducing the accumulation of the p53 antagonist ΔNp73α, prevent the UV-mediated recruitment of these transcription factors onto the TLR9 promoter, with subsequent impairment of TLR9 gene expression. This study provides new insight into the mechanism that mediates TLR9 upregulation in response to cellular stresses. In addition, we show that HPV38 E6 and E7 are able to interfere with this mechanism, providing another explanation for the possible cooperation of beta HPV types with UV radiation in skin carcinogenesis. IMPORTANCE Beta HPV types have been suggested to act as cofactors in UV-induced skin carcinogenesis by altering several cellular mechanisms activated by UV radiation. We show that the expression of TLR9, a sensor of damage-associated molecular patterns produced during cellular stress, is activated by UV radiation in primary human keratinocytes (PHKs). Two transcription factors known to be activated by UV radiation, p53 and c-Jun, play key roles in UV-activated TLR9 expression. The E6 and E7 oncoproteins from beta HPV38 strongly inhibit UV-activated TLR9 expression by preventing the recruitment of p53 and c-Jun to the TLR9 promoter. Our findings provide additional support for the role that beta HPV types play in skin carcinogenesis by preventing activation of specific pathways upon exposure of PHKs to UV radiation. Copyright © 2017 American Society for Microbiology.

Effects of Stratospheric Ozone Depletion, Solar UV Radiation, and Climate Change on Biogeochemical Cycling: Interactions and Feedbacks

EPA Science Inventory

Climate change modulates the effects of solar UV radiation on biogeochemical cycles in terrestrial and aquatic ecosystems, particularly for carbon cycling, resulting in UV-mediated positive or negative feedbacks on climate. Possible positive feedbacks discussed in this assessment...

INTERACTIONS OF SOLAR UV RADIATION AND DISSOLVED ORGANIC MATTER IN AQUATIC ENVIRONMENTS

EPA Science Inventory

Changes in the ozone layer over the past two decades have resulted in increases in solar ultraviolet (UV) radiation that reaches the surface of aquatic environments. Recent studies have demonstrated that these UV increases cause changes in photochemical reactions that affect the...

Pollen sensitivity to ultraviolet-B (UV-B) suggests floral structure evolution in alpine plants.

PubMed

Zhang, Chan; Yang, Yong-Ping; Duan, Yuan-Wen

2014-03-31

Various biotic and abiotic factors are known to exert selection pressures on floral traits, but the influence of ultraviolet-B (UV-B) light on the evolution of flower structure remains relatively unexplored. We have examined the effectiveness of flower structure in blocking radiation and the effects of UV-B on pollen viability in 42 species of alpine plants in the Hengduan Mountains, China. Floral forms were categorized as either protecting or exposing pollen grains to UV-B. The floral materials of plants with exposed and protected pollen grains were able to block UV-B at similar levels. Exposure to UV-B radiation in vitro resulted in a significantly greater loss of viability in pollen from plant species with protective floral structures. The pronounced sensitivity of protected pollen to UV-B radiation was associated with the type of flower structure. These findings demonstrate that UV-B plays an important role in the evolution of protective floral forms in alpine plants.

UV-B exposure impairs resistance to infection by Trichinella spiralis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goettsch, W.; Garssen, J.; Deijns, A.

1994-03-01

To assess the possibility that increases in UV-B exposure on the earth's surface could lead to impaired resistance to several infectious diseases, we studied the effect of UV-B exposure on resistance against Trichinella spiralis. Wistar rats, orally infected with T. spiralis larvae, were exposed to suberythemal doses of UV-B radiation daily for 5 days at different time periods before or after infection. A significant increase in the number of Trichinella larvae was found in the carcasses of rats irradiated with UV-B between 6 and 10 days after infection. These data indicate that exposure to UV-B radiation suppresses the resistance tomore » a parasitic infection. We suggested that UV-B radiation especially suppresses cellular immune responses against these worms because specific IgM, IgG, and IgE titers were not significantly altered by UV-B exposure. These data indicate that UV-B irradiation plays a role in the course of infection with T. spiralis, which suggests that increases of UV-B exposure might also lead to problems with other infectious diseases and might affect vaccination because of the interaction of UV-B irradiation with memory T-cells. 38 refs., 3 figs., 1 tab.« less

Ultraviolet and visible radiation at Barrow, Alaska: Climatology and influencing factors on the basis of version 2 National Science Foundation network data

NASA Astrophysics Data System (ADS)

Bernhard, Germar; Booth, Charles R.; Ehramjian, James C.; Stone, Robert; Dutton, Ellsworth G.

2007-05-01

Spectral ultraviolet (UV) and visible irradiance has been measured near Barrow, Alaska (71°N, 157°W), between 1991 and 2005 with a SUV-100 spectroradiometer. The instrument is part of the U.S. National Science Foundation's UV Monitoring Network. Here we present results based on the recently produced "version 2" data release, which supersedes published "version 0" data. Cosine error and wavelength-shift corrections applied to the new version increased biologically effective UV dose rates by 0-10%. Corrected clear-sky measurements of different years are typically consistent to within ±3%. Measurements were complemented with radiative transfer model calculations to retrieve total ozone and surface albedo from measured spectra and for the separation of the different factors influencing UV and visible radiation. A climatology of UV and visible radiation was established, focusing on annual cycles, trends, and the effect of clouds. During several episodes in spring of abnormally low total ozone, the daily UV dose at 305 nm exceeded the climatological mean by up to a factor of 2.6. Typical noontime UV Indices during summer vary between 2 and 4; the highest UV Index measured was 5.0 and occurred when surface albedo was unusually high. Radiation levels in the UV-A and visible exhibit a strong spring-autumn asymmetry. Irradiance at 345 nm peaks on approximately 20 May, 1 month before the solstice. This asymmetry is caused by increased cloudiness in autumn and high albedo in spring, when the snow covered surface enhances downwelling UV irradiance by up to 57%. Clouds reduce UV radiation at 345 nm on average by 4% in March and by more than 40% in August. Aerosols reduce UV by typically 5%, but larger reductions were observed during Arctic haze events. Stratospheric aerosols from the Pinatubo eruption in 1991 enhanced spectral irradiance at 305 nm for large solar zenith angles. The year-to-year variations of spectral irradiance at 305 nm and of the UV Index are mostly caused by variations in total ozone and cloudiness. Changes in surface albedo that may occur in the future can have a marked impact on UV levels between May and July. No statistically significant trends in monthly mean noontime irradiance were found.

Study of long term effect of Solar UV and X-ray radiation on the VLF signals

NASA Astrophysics Data System (ADS)

Ray, Suman; Chakrabarti, Sandip Kumar; Sanki, Dipak

2016-07-01

Very Low Frequency (VLF) is one of the bands of Radio waves having frequencies lying between 3-30 KHz, with wavelengths 100-10 Km. It propagates through the Earth-ionosphere wave-guide which is formed by lower part of the ionosphere and upper part of Earth's surface. Ionosphere is the ionized component of upper atmosphere. In the present work, we have studied the long term effect of the high energy solar UV and X-ray radiation on the VLF signals. We have analyzed the VLF signal transmitted at 24 KHz from NAA (Cutler, Maine) and received at Moore Observatory in Brownsboro, Kentucky. Also we have collected X-ray and UV data to study the long term effect of UV and X-ray radiation on the VLF signal. We have analyzed the VLF signal for 2007 to 2015. We calculate the average diurnal peak amplitude of the VLF signal for each day and compare it with the UV and X-ray solar radiation. We found that the correlation coefficient of diurnal peak VLF signal amplitude with both solar X-ray and UV radiation is 0.7 indicating a strong correlation between these two phenomena.

Replicated mesocosm study on the role of natural ultraviolet radiation in high CDOM, shallow lakes.

PubMed

Pérez, A Patricia; Diaz, Mónica M; Ferraro, Marcela A; Cusminsky, Gabriela C; Zagarese, Horacio E

2003-02-01

The role of ultraviolet radiation on shallow, high CDOM (colored dissolved organic matter) lakes was investigated during two consecutive summers (1999 and 2000) in replicated mesocosms (rectangular fiberglass tanks). Each tank (volume: 300 L; depth: 40 cm) was covered with a layer (approximately 3 cm) of sediment from lake El Toro (40 degrees 14' S; 70 degrees 22' W) and filled with filtered water. The experimental design consisted of two treatments: full natural radiation (UV-exposed) and natural radiation without ultraviolet radiation (UV-shielded). UV-exposed and UV-shielded treatments differed in most studied variables as revealed by repeated measures ANOVA. UV-exposed tanks displayed lower CDOM levels (dissolved absorbance) of lower average molecular size (absorbance ratio between 250 and 365 nm), higher bacterial biomass, and lower chlorophyll a concentration. The effect on consumers (rotifers and crustaceans) was less noticeable. The results are consistent with UV stimulation of bacteria production mediated by higher rates of CDOM photobleaching, and the photoinhibition of planktonic algae. Thus, a major effect of UVR in shallow, high CDOM ecosystems appears to be the stimulation of heterotrophic pathways and a simultaneous inhibition of photoautotrophs.

Repair of Ultraviolet Radiation Damage in Sensitive Mutants of Micrococcus radiodurans

PubMed Central

Moseley, B. E. B.

1969-01-01

Various aspects of the repair of ultraviolet (UV) radiation-induced damage were compared in wild-type Micrococcus radiodurans and two UV-sensitive mutants. Unlike the wild type, the mutants are more sensitive to radiation at 265 nm than at 280 nm. The delay in deoxyribonucleic acid (DNA) synthesis following exposure to UV is about seven times as long in the mutants as in the wild type. All three strains excise UV-induced pyrimidine dimers from their DNA, although the rate at which cytosine-thymine dimers are excised is slower in the mutants. The three strains also mend the single-strand breaks that appear in the irradiated DNA as a result of dimer excision, although the process is less efficient in the mutants. It is suggested that the increased sensitivity of the mutants to UV radiation may be caused by a partial defect in the second step of dimer excision. PMID:5773016

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

USGS Publications Warehouse

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.

Time Profile of Cosmic Radiation Exposure During the EXPOSE-E Mission: The R3DE Instrument

PubMed Central

Horneck, Gerda; Häder, Donat-Peter; Schuster, Martin; Richter, Peter; Lebert, Michael; Demets, Rene

2012-01-01

Abstract The aim of this paper is to present the time profile of cosmic radiation exposure obtained by the Radiation Risk Radiometer-Dosimeter during the EXPOSE-E mission in the European Technology Exposure Facility on the International Space Station's Columbus module. Another aim is to make the obtained results available to other EXPOSE-E teams for use in their data analysis. Radiation Risk Radiometer-Dosimeter is a low-mass and small-dimension automatic device that measures solar radiation in four channels and cosmic ionizing radiation as well. The main results of the present study include the following: (1) three different radiation sources were detected and quantified—galactic cosmic rays (GCR), energetic protons from the South Atlantic Anomaly (SAA) region of the inner radiation belt, and energetic electrons from the outer radiation belt (ORB); (2) the highest daily averaged absorbed dose rate of 426 μGy d−1 came from SAA protons; (3) GCR delivered a much smaller daily absorbed dose rate of 91.1 μGy d−1, and the ORB source delivered only 8.6 μGy d−1. The analysis of the UV and temperature data is a subject of another article (Schuster et al., 2012). Key Words: Ionizing radiation—R3D—ISS. Astrobiology 12, 403–411. PMID:22680687

DEMONSTRATION BULLETIN - ULTROX INTERNATIONAL, INC. ULTRAVIOLET RADIATION AND OXIDATION

EPA Science Inventory

The ultraviolet (UV) radiation/oxidation treatment technology developed by Ultrox International uses a combination of UV radiation, ozone, and hydrogen peroxide to oxidize organic compounds in water. Various operating parameters can be adjusted in the Ultrox® system to enhan...

Effects of ultraviolet radiation and temperature on the ultrastructure of zoospores of the brown macroalga Laminaria hyperborea.

PubMed

Steinhoff, F S; Wiencke, C; Müller, R; Bischof, K

2008-05-01

The interactive effects of an 8 h exposure to UV radiation and altered temperatures on the ultrastructure and germination of zoospores of the sublittoral brown alga Laminaria hyperborea (Gunn.) Foslie were investigated for the first time. Spores were exposed to four temperatures (2, 7, 12 and 17 degrees C) and three light regimes (PAR, PAR + UV-A, PAR + UV-A+UV-B). Freshly-released spores of L. hyperborea lack a cell wall and contain a nucleus with fine granular nucleoplasm and a nucleolus, one chloroplast, several mitochondria, dictyosomes and an endoplasmatic reticulum. Further, several kinds of so-called adhesive vesicles, lipid globuli and physodes containing UV-absorbing phlorotannins are embedded in the cytoplasm. No eye-spot is present. Physodes were found but they were rare and small. After an 8 h exposure to UV-B, the nucleoplasm had a mottled structure, chloroplasts contained plastoglobuli, the structure of the mitochondria changed from crista- to sacculus-type and germination was strongly inhibited at all temperatures. UV-A only had an impact on the ultrastructure at the highest temperature tested. The strongest effects were found at 17 degrees C, where germination was reduced to 35%, 32% and 9% after exposure to PAR, PAR+UV-A and PAR + UV-A + UV-B, respectively. This study indicates that UV-B radiation has strong damaging effects on the physiology and ultrastructure of zoospores of L. hyperborea. The results are important for developing scenarios for the effect of enhanced UV radiation and increasing temperatures caused by global climate changes.

Development of high power UV irradiance meter calibration device

NASA Astrophysics Data System (ADS)

Xia, Ming; Gao, Jianqiang; Yin, Dejin; Li, Tiecheng

2016-09-01

With the rapid development of China's economy, many industries have more requirements for UV light applications, such as machinery manufacturing, aircraft manufacturing using high power UV light for detection, IT industry using high power UV light for curing component assembly, building materials, ink, paint and other industries using high power UV light for material aging test etc. In these industries, there are many measuring instruments for high power UV irradiance which are need to traceability. But these instruments are mostly imported instruments, these imported UV radiation meter are large range, wide wavelength range and high accuracy. They have exceeded our existing calibration capability. Expand the measuring range and improve the measurement accuracy of UV irradiance calibration device is a pressing matter of the moment. The newly developed high power UV irradiance calibration device is mainly composed of high power UV light, UV filter, condenser, UV light guide, optical alignment system, standard cavity absolute radiometer. The calibration device is using optical alignment system to form uniform light radiation field. The standard is standard cavity absolute radiometer, which can through the electrical substitution method, by means of adjusting and measuring the applied DC electric power at the receiver on a heating wire, which is equivalent to the thermo-electromotive force generated by the light radiation power, to achieve absolute optical radiation measurement. This method is the commonly used effective method for accurate measurement of light irradiation. The measuring range of calibration device is (0.2 200) mW/cm2, and the uncertainty of measurement results can reached 2.5% (k=2).

UV Radiation Damage and Bacterial DNA Repair Systems

ERIC Educational Resources Information Center

Zion, Michal; Guy, Daniel; Yarom, Ruth; Slesak, Michaela

2006-01-01

This paper reports on a simple hands-on laboratory procedure for high school students in studying both radiation damage and DNA repair systems in bacteria. The sensitivity to ultra-violet (UV) radiation of both "Escherichia coli" and "Serratia marcescens" is tested by radiating them for varying time periods. Two growth temperatures are used in…

Photosynthetically active radiation (PAR) x ultraviolet radiation (UV) interact to initiate solar injury in apple

USDA-ARS?s Scientific Manuscript database

Sunburn or solar injury (SI) in apple is associated with high temperature, high visible light and ultraviolet radiation (UV). Fruit surface temperature (FST) thresholds for SI related disorders have been developed but there are no thresholds established for solar radiation. The objectives of the s...

Photocatalytic degradation of rhodamine B, paracetamol and diclofenac sodium by supported titania-based catalysts from petrochemical residue: effect of doping with magnesium.

PubMed

da Silva, William Leonardo; Lansarin, Marla Azário; Dos Santos, João Henrique Z; Silveira, Fernando

2016-11-01

Three different lots of a residual Ziegler-Natta catalyst slurry (bearing Ti and Mg) obtained from an industrial petrochemical plant were employed as sources for the photocatalyst supported on silica. The effect of additional magnesium (1.0-25.0 wt% Mg/SiO 2 ) on the photocatalytic properties of the doped materials was investigated. Doping the titania-based photocatalyst with Mg results in a shift in the absorption threshold toward the visible spectrum. The optical band gap energy of the bare supported photocatalyst was in the range of 2.5 eV and shifted to 1.72 eV after 25 wt% Mg doping. The systems were evaluated for the photodegradation of one dye (rhodamine B (RhB)) and two drugs (paracetamol and diclofenac sodium) either under ultraviolet (UV) (365 nm - UVA) or visible radiation, separately. Among the evaluated systems, doping with 25 wt% Mg afforded the highest degradation values for the target molecules under UV and visible radiation (i.e. 87%, 60% and 55% of the RhB, paracetamol and diclofenac under UV, respectively, and 82%, 48.3% and 48% under visible irradiation, respectively).

INTERACTIVE EFFECTS OF SOLAR UV RADIATION AND CLIMATE CHANGE ON BIOGEOCHEMICAL CYCLING

EPA Science Inventory

This paper assesses research on the interactions of UV radiation (280-400 nm) and global climate change with global biogeochemical cycles at the Earth's surface. The effects of UV-B (280-315 nm), which are dependent on the stratospheric ozone layer, on biogeochemical cycles are o...

Some Thoughts on Teaching about Ultraviolet Radiation

ERIC Educational Resources Information Center

Thumm, Walter

1975-01-01

Describes the major obstacles in the study of ultraviolet radiation (UV). Presents the beneficial aspects of UV such as vitamin O production, sterilization, clinical treatment of diseases and wounds, and the marking of patients for radiotherapy. Warns of the dangers of UV exposure such as skin cancer and early aging. (GS)

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

EPA Science Inventory

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

Probing the conditions within Photo-dissociation Regions with high resolution near-infrared spectroscopy of UV-excited molecular hydrogen

NASA Astrophysics Data System (ADS)

Kaplan, Kyle; Dinerstein, Harriet L.; Jaffe, Daniel Thomas

2017-01-01

UV radiation regulates the energetics, ionization, and chemistry in much of the ISM. Regions between hot ionized and cool molecular gas where non-ionizing far-UV radiation dominates the state of the gas are called Photo-Dissociation or Photon-Dominated Regions (PDRs). PDRs are found in regions of high-mass star formation, planetary nebulae, and other environments that contain strong far-UV radiation fields. Hydrogen molecules (H2) are pumped by far-UV photons into excited rotational-vibrational levels of the ground electronic state, which give rise to a rich array of transitions in the near to mid-infrared. These transitions make an excellent probe of the physical conditions within a PDR. I will present near-IR spectra taken with the Immersion GRating Infrared Spectrometer (IGRINS; Park et al. 2014, Proc. SPIE, 9147), a novel, sensitive spectrometer with high spectral resolving power (R~45000) and instantaneous broad wavelength coverage (1.45-2.45 μm). Using IGRINS, I obtained deep spectra and measured up to 100 H2 rotational-vibrational transitions in the well-studied Orion Bar PDR, four other star formation complexes, and over a dozen planetary nebulae. Measurements of many lines from a wide range of vibrational states (v=1 to 13), rotational states (J=1 to 13), and excitation energies provides leverage for constraining the overall level populations and discerning the state of and physical processes within the gas. This combination of high spectral and spatial resolution enables us to distinguish previously unresolved spatio-kinematical components with distinct intrinsic spectra and excitation mechanisms (e.g. shocks vs. radiative excitation) within some individual planetary nebulae. I use the plasma simulation code Cloudy (Ferland et al. 2013, ApJ, 757, 79) as a tool for interpreting the observed H2 line ratios. Some sources are well fit by models with a single temperature and density, consistent with emission from a narrow region of the overall PDR structure. Populations of certain levels are more sensitive than others to specific physical parameters such as gas kinetic temperature or density.I acknowledge support from the following grants: NSF 1229522, NSF 0708245, and JPL RSA 1427884.

Corneal epithelium and UV-protection of the eye.

PubMed

Ringvold, A

1998-04-01

To study UV-absorption and UV-induced fluorescence in the bovine corneal epithelium. Spectrophotometry and spectrofluorimetry. The corneal epithelium absorbs UV-B radiation mainly owing to its content of protein, RNA, and ascorbate. Some of the absorbed energy is transformed to the less biotoxic UV-A radiation by fluorescence. RNA and ascorbate reduce tissue fluorescence. The corneal epithelium acts as a UV-filter, protecting internal eye structures through three different mechanisms: (1) Absorption of UV-B roughly below 310 nm wavelength. (2) Fluorescence-mediated ray transformation to longer wavelengths. (3) Fluorescence reduction. The extremely high ascorbate concentration in the corneal epithelium has a key role in two of these processes.

Influence of ambient ultraviolet radiation on Bufo calamita egg development in a semiarid zone (Catalonia, Spain).

PubMed

Oromi, Neus; Marquis, Olivier; Miaud, Claude; Sanuy, Delfi

2008-01-01

Several experiments have shown that ambient ultraviolet-B radiation (UV-B) has negative effects on the development of amphibians' embryos. We studied the effects of UV-B radiation on development, survival and frequency of deformity during egg development in the Natterjack toad (Bufo calamita) from a semiarid region of Lleida (Catalonia, Spain). Eggs exposed to ambient levels of UV-B and those protected from UV-B with a filter exhibited similar developmental rate, mortality rate and frequency of developmental anomalies. These experiments show that eggs of Bufo calamita of the studied population are able to develop normally during embryonic period when exposed to current high levels of UV-B observed in Catalonia. These results will be used as reference for future studies on geographic variation in UV-B tolerance in this species.

The Diffuse Radiation Field at High Galactic Latitudes

NASA Astrophysics Data System (ADS)

Akshaya, M. S.; Murthy, Jayant; Ravichandran, S.; Henry, R. C.; Overduin, James

2018-05-01

We have used GALEX observations of the north and south Galactic poles to study the diffuse ultraviolet background at locations where the Galactic light is expected to be at a minimum. We find offsets of 230–290 photon units in the far-UV (1531 Å) and 480–580 photon units in the near-UV (2361 Å). Of this, approximately 120 photon units can be ascribed to dust-scattered light and another 110 photon units (190 in the near-UV) to extragalactic radiation. The remaining radiation is, as yet, unidentified and amounts to 120–180 photon units in the far-UV and 300–400 photon units in the near-UV. We find that molecular hydrogen fluorescence contributes to the far-UV when the 100 μm surface brightness is greater than 1.08 MJy sr‑1.

Enhanced Radiation Resistance of Methanosarcina soligelidi SMA-21, a New Methanogenic Archaeon Isolated from a Siberian Permafrost-Affected Soil in Direct Comparison to Methanosarcina barkeri.

PubMed

Morozova, Daria; Moeller, Ralf; Rettberg, Petra; Wagner, Dirk

2015-11-01

Permafrost-affected soils are characterized by a high abundance and diversity of methanogenic communities, which are considered suitable model organisms for potential life on Mars. Methanogens from Siberian permafrost have been proven to be highly resistant against divers stress conditions such as subzero temperatures, desiccation, and simulated thermophysical martian conditions. Here, we studied the radiation resistance of the currently described new species Methanosarcina soligelidi SMA-21, which was isolated from a Siberian permafrost-affected soil, in comparison to Methanosarcina barkeri, which is used as a reference organism from a nonpermafrost soil environment. Both strains were exposed to solar UV and ionizing radiation to assess their limits of survival. Methanosarcina soligelidi exhibit an increase in radiation resistance to UV (2.5- to 13.8-fold) and ionizing radiation (46.6-fold) compared to M. barkeri. The F10 (UVC) and D10 (X-rays) values of M. soligelidi are comparable to values for the well-known, highly radioresistant species Deinococcus radiodurans. In contrast, the radiation response of M. barkeri was highly sensitive to UV and ionizing radiation comparably to Escherichia coli and other radiosensitive microorganisms. This study showed that species of the same genus respond differently to UV and ionizing radiation, which might reflect the adaptation of Methanosarcina soligelidi SMA-21 to the harsh environmental conditions of the permafrost habitat. Methanogenic archaea-Environmental UV-Ionizing radiation-Permafrost-Radiation resistance-Mars.

Accretion Disks in Supersoft X-ray Sources

NASA Technical Reports Server (NTRS)

Popham, Robert; DiStefano, Rosanne

1996-01-01

We examine the role of the accretion disk in the steady-burning white dwarf model for supersoft sources. The accretion luminosity of the disk is quite small compared to the nuclear burning luminosity of the central source. Thus, in contrast to standard accretion disks, the main role of the disk is to reprocess the radiation from the white dwarf. We calculate models of accretion disks around luminous white dwarfs and compare the resulting disk fluxes to optical and UV observations of the LMC supersoft sources CAL 83, CAL 87, and RX J0513.9-6951. We find that if the white dwarf luminosity is near the upper end of the steady-burning region, and the flaring of the disk is included, then reprocessing by the disk can account for the UV fluxes and a substantial fraction of the optical fluxes of these systems. Reprocessing by the companion star can provide additional optical flux, and here too the disk plays an important role: since the disk is fairly thick, it shadows a significant fraction of the companion's surface.

A Census of the LyC Photons that Form the UV Background During Reionization

NASA Astrophysics Data System (ADS)

Katz, Harley; Kimm, Taysun; Haehnelt, Martin; Sijacki, Debora; Rosdahl, Joakim; Blaizot, Jeremy

2018-05-01

We present a new, on-the-fly photon flux and absorption tracer algorithm designed to directly measure the contribution of different source populations to the metagalactic UV background and to the ionisation fraction of gas in the Universe. We use a suite of multifrequency radiation hydrodynamics simulations that are carefully calibrated to reproduce a realistic reionization history and galaxy properties at z ≥ 6, to disentangle the contribution of photons emitted by different mass haloes and by stars with different metallicities and ages to the UV background during reionization. While at very early cosmic times low mass, metal poor haloes provide most of the LyC photons, their contribution decreases steadily with time. At z = 6 it is the photons emitted by massive systems (Mhalo/M⊙ > 1010 h-1) and by the metal enriched stars (10-3 < Z/Z⊙ < 10-1.5) that provide the largest contribution to the ionising UV background. We demonstrate that there are large variations in the escape fraction depending on the source, with the escape fraction being highest (˜45 - 60%) for photons emitted by the oldest stars that penetrate into the IGM via low opacity channels carved by the ionising photons and supernova from younger stars. Before HII regions begin to overlap, the photoionisation rate strongly fluctuates between different, isolated HII bubbles, depending on the embedded ionising source, which we suggest may result in spatial variations in the properties of dwarf galaxies.

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

PubMed

Schouten, P; Parisi, A V

2011-02-07

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

Importance of biologically active aurora-like ultraviolet emission: stochastic irradiation of Earth and Mars by flares and explosions.

PubMed

Smith, David S; Scalo, John; Wheeler, J Craig

2004-10-01

Habitable planets will be subject to intense sources of ionizing radiation and fast particles from a variety of sources--from the host star to distant explosions--on a variety of timescales. Monte Carlo calculations of high-energy irradiation suggest that the surfaces of terrestrial-like planets with thick atmospheres (column densities greater than about 100 g cm(-2)) are well protected from directly incident X-rays and gamma-rays, but we find that sizeable fractions of incident ionizing radiation from astrophysical sources can be redistributed to biologically and chemically important ultraviolet wavelengths, a significant fraction of which can reach the surface. This redistribution is mediated by secondary electrons, resulting from Compton scattering and X-ray photoabsorption, the energies of which are low enough to excite and ionize atmospheric molecules and atoms, resulting in a rich aurora-like spectrum. We calculate the fraction of energy redistributed into biologically and chemically important wavelength regions for spectra characteristic of stellar flares and supernovae using a Monte-Carlo transport code and then estimate the fraction of this energy that is transmitted from the atmospheric altitudes of redistribution to the surface for a few illustrative cases. For atmospheric models corresponding to the Archean Earth, we assume no significant ultraviolet absorbers, only Rayleigh scattering, and find that the fraction of incident ionizing radiation that is received at the surface in the form of redistributed ultraviolet in the biologically relevant 200-320 nm region (UV-C and UV-B bands) can be up to 4%. On the present-day Earth with its ultraviolet ozone shield, this fraction is found to be 0.2%. Both values are many orders of magnitude higher than the fraction of direct ionizing radiation reaching the surface. This result implies that planetary organisms will be subject to mutationally significant, if intermittent, fluences of UV-B and harder radiation even in the presence of a narrow-band ultraviolet shield like ozone. We also calculate the surficial transmitted fraction of ionizing radiation and redistributed ultraviolet radiation for two illustrative evolving Mars atmospheres whose initial surface pressures were 1 bar. We discuss the frequency with which redistributed ultraviolet flux from parent star flares exceeds the parent star ultraviolet flux at the planetary surface. We find that the redistributed ultraviolet from parent star flares is probably a fairly rare intermittent event for habitable zone planets orbiting solar-type stars except when they are young, but should completely dominate the direct steady ultraviolet radiation from the parent star for planets orbiting all stars less massive than about 0.5 solar masses. Our results suggest that coding organisms on such planets (and on the early Earth) may evolve very differently than on contemporary Earth, with diversity and evolutionary rate controlled by a stochastically varying mutation rate and frequent hypermutation episodes.

INTERNAL FILTERS: PROSPECTS FOR UV-ACCLIMATION IN HIGHER PLANTS

EPA Science Inventory

Wavelength-selective absorption of solar radiation within plant leaves allows penetration of visible radiation (400-700nm) to the chloroplasts, while removing much of the damaging ultraviolet-B (UV-B, 280-320 nm) radiation. Flavonoids are important in this wavelength-selective ab...

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

PubMed

Qureshi, Zubair; Yassin, Mohamed H

2013-06-01

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

UV clothing and skin cancer.

PubMed

Tarbuk, Anita; Grancarić, Ana Marija; Situm, Mirna; Martinis, Mladen

2010-04-01

Skin cancer incidence in Croatia is steadily increasing in spite of public and governmental permanently measurements. It is clear that will soon become a major public health problem. The primary cause of skin cancer is believed to be a long exposure to solar ultraviolet (UV) radiation. The future designers of UV protective materials should be able to block totally the ultraviolet radiation. The aim of this paper is to present results of measurements concerning UV protecting ability of garments and sun-screening textiles using transmission spectrophotometer Cary 50 Solarscreen (Varian) according to AS/NZS 4399:1996; to show that standard clothing materials are not always adequate to prevent effect of UV radiation to the human skin; and to suggest the possibilities for its improvement for this purpose.

Oxidative damage in response to natural levels of UV-B radiation in larvae of the tropical sea urchin Tripneustes gratilla.

PubMed

Lister, Kathryn Naomi; Lamare, Miles D; Burritt, David J

2010-01-01

To assess the effects of UV radiation (280-400nm) on development, oxidative damage and antioxidant defence in larvae of the tropical sea urchin Tripneustes gratilla, a field experiment was conducted at two depths in Aitutaki, Cook Islands (18.85°S, 159.75°E) in May 2008. Compared with field controls (larvae shielded from UV-R but exposed to VIS-radiation), UV-B exposure resulted in developmental abnormality and increases in oxidative damage to proteins (but not lipids) in embryos of T. gratilla held at 1m depth. Results also indicated that larvae had the capacity to increase the activities of protective antioxidant enzymes when exposed to UV-B. The same trends in oxidative damage and antioxidant defence were observed for embryos held at 4m, although the differences were smaller and more variable. In contrast to UV-B exposure, larvae exposed to UV-A only showed no significant increases in abnormality or oxidative damage to lipids and proteins compared with field controls. This was true at both experimental depths. Furthermore, exposure to UV-A did not cause a significant increase in the activities of antioxidants. This study indicates that oxidative stress is an important response of tropical sea urchin larvae to exposure to UV radiation. © 2010 The Authors. Journal Compilation. The American Society of Photobiology.

Combined effects of lanthanum(III) and elevated ultraviolet-B radiation on root growth and ion absorption in soybean seedlings.

PubMed

Huang, Guang Rong; Wang, Li Hong; Zhou, Qing

2014-03-01

Rare earth element accumulation in the soil and elevated ultraviolet (UV)-B radiation (280-315 nm) are important environmental issues worldwide. To date, there have been no reports concerning the combined effects of lanthanum (La)(III) and elevated UV-B radiation on plant roots in regions where the two issues occur simultaneously. Here, the combined effects of La(III) and elevated UV-B radiation on the growth, biomass, ion absorption, activities, and membrane permeability of roots in soybean (Glycine max L.) seedlings were investigated. A 0.08 mmol L(-1) La(III) treatment improved the root growth and biomass of soybean seedlings, while ion absorption, activities, and membrane permeability were obviously unchanged; a combined treatment with 0.08 mmol L(-1) La(III) and elevated UV-B radiation (2.63/6.17 kJ m(-2) day(-1)) exerted deleterious effects on the investigated indices. The deleterious effects were aggravated in the other combined treatments and were stronger than those of treatments with La(III) or elevated UV-B radiation alone. The combined treatment with 0.24/1.20 mmol L(-1) La(III) and elevated UV-B radiation exerted synergistically deleterious effects on the growth, biomass, ion absorption, activities, and membrane permeability of roots in soybean seedlings. In addition, the deleterious effects of the combined treatment on the root growth were due to the inhibition of ion absorption induced by the changes in the root activity and membrane permeability.

[The impact of UV radiation B and C in vitro on different of bacteria strains isolated from patients hospitalized in the Warsaw Medical University Clinics].

PubMed

Rongies, Witold; Wultańska, Dorota; Kot, Katarzyna; Bogusz, Aleksandra; Rongies, Magdalena; Świercz, Paweł; Swierszcz, Paweł; Lewandowska, Monika; Cholewińska, Grazyna; Meisel-Mikołajczyk, Felicja

2011-01-01

Infections in human body caused by various microbes are a significant problem in modern medicine. Special attention is put to infections of wounds, which are a significant threat to the life of patients. Attempts to treat these wounds base mainly on the application of various chemical preparations (locally) and systematic antibiotic treatment. UV radiation, because of its anti-bacterial activity, appear a complementary issue in therapy. AIM OF THE SURVEY: The aim of this study was an examination of the sensitivity of bacteria strains isolated from patients hospitalised in the Warsaw Medical University clinics, and prove that antibiotics and operation of UV B and C radiation with Endolamp 474 may become a complementary or alternative method of treatment. The study used 65 strains grown aerobically (15 strains of Escherichia coli, 20 strains of Pseudomonas aeruginosa, 15 strains of Staphylococcus aureus, 15 strains of Streptococcus and Enterococcus sp). The same strains were planted on different excipients and were subjected to UV radiation using Endolamp 474. Correctly prepared strains were radiated from a 25 cm distance in various durations (from 5 seconds to 105 seconds). As a result of UV irradiation of microorganisms studied B and C using 474 Endolampy received varied, but the great sensitivity to the effects of this radiation, in all tested bacterial strains. UV radiation on microorganisms requires further study, also in vivo.

Investigation of Carbonaceous Aerosol Optical Properties to Understand Impacts on Air Quality and Composition

NASA Astrophysics Data System (ADS)

Olson, Michael R.

The optical properties of carbonaceous aerosols were investigated to understand the impact source emissions and ambient particulate matter (PM) have on atmospheric radiative forcing. Black carbon (BC) is a strong absorber of visible light and contributes highly to atmospheric radiative forcing, therefore it is important to link BC properties to combustion emission sources. Brown carbon (BrC) is poorly understood and may be an important contributor to both positive and negative radiative forcing. The research investigates these primary knowledge gaps. The optical properties of carbonaceous aerosols were investigated to understand the impact source emissions and ambient particulate matter (PM) have on atmospheric radiative forcing. Black carbon (BC) is a strong absorber of visible light and contributes highly to atmospheric radiative forcing, therefore it is important to link BC properties to combustion emission sources. Brown carbon (BrC) is poorly understood and may be an important contributor to both positive and negative radiative forcing. The research investigates these primary knowledge gaps. Multiple methods were developed and applied to quantify the mass absorption cross-section (MAC) at multiple wavelengths of source and ambient samples. The MAC of BC was determined to be approximately 7.5 m2g-1 at 520nm. However, the MAC was highly variable with OC fraction and wavelength. The BrC MAC was similar for all sources, with the highest absorption in the UV at 370nm; the MAC quickly decreases at larger wavelengths. In the UV, the light absorption by BrC could exceed BC contribution by over 100 times, but only when the OC fraction is large (>90%) as compared to the total carbon. BrC was investigated by measuring the light absorption of solvent extracted fractions in water, dichloromethane, and methanol. Source emissions exhibited greater light absorption in methanol extractions as compared to water and DCM extracts. The BrC MAC was 2.4 to 3.7 m2g-1 at 370nm in methanol. Ambient samples showed similar MACs for the water and methanol extracts. Dichloromethane extracts did not have a significant light absorption characteristics for ambient samples. BrC and BC were measured in Beijing, China. Both were reduced significantly when restrictive air pollution controls were put in place. The industrial regions south and east of Beijing were the highest contributors to ambient BrC and BC. The controls reduced BrC more than BC as compared to observations during the regions heating period. Using the color characteristics of ambient PM, a model was developed to estimate elemental and organic carbon (EC/OC). The method will allow fast and cost effective quantification of PM composition in combination with large climate and health studies, especially in the developing world.

Response of Two Plant Species to Two Ultraviolet-B Radiation Regimes

NASA Technical Reports Server (NTRS)

Levy, Daniel L.; Skiles, J. W.; Peterson, David (Technical Monitor)

1996-01-01

The depleted stratospheric ozone layer has been directly linked to increased levels of ultraviolet radiation at the earth's surface. It is important to understand what effect this will have on plants. We tested the hypothesis that in response to increased UV-B radiation (280-320 man), soybean (Glycine max Merrill) and alfalfa (Mercado Saliva L.) would produce higher concentrations of flavonoids than plants screened from UV-B. Soybean and alfalfa plants were grown successively in a growth chamber that provided UV-B radiation intensities 45% above summer field levels. A wooden frame was used to suspend mylar-D film over one group of plants and mono-acetate film over another group. Mylar is opaque in the 280-316 nm range, and acetate absorbs most radiation from 280-290 nm and then reduces intensities in the 290-320 nm range by roughly 15%. Leaf chlorophyll concentration was determined with a Minolta SPAD-502 chlorophyll meter; the BRAD meter was calibrated with N,N- extractions. Flavonoids were extracted with an acidified methanol/water solution. Soybean grown under the acetate treatment showed 26% smaller internodal lengths and higher concentrations of flavonoids compared to plants grown under mylar. Significant results for alfalfa included 22% greater leaf flavonoid concentration under acetate, 14% greater leaf chlorophyll concentration under mylar, and 32% greater above-ground biomass under mylar. We found that increased UV-B radiation leads to increased production of UV-B absorbing compounds (i.e. flavonoids) in soybean and alfalfa leaves. This suggests that a protective mechanism in these plants is triggered by UV-B. In response, flavonoids are produced that absorb UV-B, and consequently decrease potentially damaging effects to the plants. In addition, we hypothesize that this flavonoid protection mechanism saturates at certain UV-B intensities.

Caffeine Eye Drops Protect Against UV-B Cataract

PubMed Central

Kronschläger, Martin; Löfgren, Stefan; Yu, Zhaohua; Talebizadeh, Nooshin; Varma, Shambhu D.; Söderberg, Per

2013-01-01

The purpose of this study was to investigate if topically applied caffeine protects against in vivo ultraviolet radiation cataract and if so, to estimate the protection factor. Three experiments were carried out. First, two groups of Sprague-Dawley rats were pre-treated with a single application of either placebo or caffeine eye drops in both eyes. All animals were then unilaterally exposed in vivo to 8 kJ/m2 UV-B radiation for 15 min. One week later, the lens GSH levels were measured and the degree of cataract was quantified by measurement of in vitro lens light scattering. In the second experiment, placebo and caffeine pre-treated rats were divided in five UV-B radiation dose groups, receiving 0.0, 2.6, 3.7, 4.5 or 5.2 kJ/m2 UV-B radiation in one eye. Lens light scattering was determined after one week. In the third experiment, placebo and caffeine pre-treated rats were UV-B-exposed and the presence of activated caspase-3 was visualized by immunohistochemistry. There was significantly less UV-B radiation cataract in the caffeine group than in the placebo group (95% confidence interval for mean difference in lens light scattering between the groups = 0.10 ± 0.05 tEDC), and the protection factor for caffeine was 1.23. There was no difference in GSH levels between the placebo- and the caffeine group. There was more caspase-3 staining in UV-B-exposed lenses from the placebo group than in UV-B-exposed lenses from the caffeine group. Topically applied caffeine protects against ultraviolet radiation cataract, reducing lens sensitivity 1.23 times. PMID:23644096

The natural and radiatively perturbed troposphere. CIAP monograph 4. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1975-09-01

The Climatic Impact Assessment Program (CIAP) of the U.S. Department of Transportation is charged with the 'assessment' of the impact of future aircraft fleets and other vehicles operating in, or transiting through, the stratosphere. Monograph 4 considers the perturbations of the UV radiation and the climate at the earth's surface, which could be caused by the emissions of engine effluents from a potential, large-scale operation of aircraft in the lower stratosphere. Perturbation of the UV radiation depends primarily on the magnitude of the NOx emission index (i.e., g of NO/sub 2//kg of fuel), since the NOx effluents would produce anmore » ozone column decrease and, therefore, a UV radiation increase at the earth's surface. Monograph 4 treats the problem of the UV radiation increase from solutions of the radiative transfer equation for clear sky conditions. These solutions yield the maximum increase in the direct and diffuse components of UV radiation as a function of wavelength, solar zenith angle, and ozone decrease. Perturbations of the earth's climate would depend on the magnitude of the NOx, SO2, and H2O engine effluents. In contrast to predicting UV radiation changes, it is impossible to conclusively predict the climate perturbations at the present time: the current understanding of the processes controlling the variability of the earth's climate, i.e., the general circulations of air in the atmosphere and sea water in the oceans, is limited. Considerations of climate perturbations are restricted to partial descriptions of geophysical phenomena, involving the use of mechanistic models to describe the temperature radiation couplings in time scales of decades, which seems to be appropriate for CIAP. (GRA)« less

Interaction of moderate UV-B exposure and temperature on the formation of structurally different flavonol glycosides and hydroxycinnamic acid derivatives in kale (Brassica oleracea var. sabellica).

PubMed

Neugart, Susanne; Fiol, Michaela; Schreiner, Monika; Rohn, Sascha; Zrenner, Rita; Kroh, Lothar W; Krumbein, Angelika

2014-05-07

Kale has a high number of structurally different flavonol glycosides and hydroxycinnamic acid derivatives. In this study we investigated the interaction of moderate UV-B radiation and temperature on these compounds. Kale plants were grown at daily mean temperatures of 5 or 15 °C and were exposed to five subsequent daily doses (each 0.25 kJ m(-2) d(-1)) of moderate UV-B radiation at 1 d intervals. Of 20 phenolic compounds, 11 were influenced by an interaction of UV-B radiation and temperature, e.g., monoacylated quercetin glycosides. Concomitantly, enhanced mRNA expression of flavonol 3'- hydroxylase showed an interaction of UV-B and temperature, highest at 0.75 kJ m(-2) and 15 °C. Kaempferol glycosides responded diversely and dependent on, e.g., the hydroxycinnamic acid residue. Compounds containing a catechol structure seem to be favored in the response to UV-B. Taken together, subsequent exposure to moderate UV-B radiation is a successful tool for enhancing the flavonoid profile of plants, and temperature should be considered.

Further comparison of MODTRAN 5 to measured data in the UV band

NASA Astrophysics Data System (ADS)

Smith, Leon; Richardson, Mark; Ayling, Richard; Barlow, Nick

2014-10-01

The ability to accurately model background radiation from the sun is important in understanding the operation of missile systems with ultraviolet (UV) guard channels. In theory a missile system's UV channel detects a target's silhouette, caused by its `negative contrast' with respect to background UV radiation. The variation in background levels of UV will therefore have an effect on the operability of a missile system that utilises a UV channel. In this paper an update on the measurement and comparison of background UV-A radiation to data produced by Moderate Resolution Atmospheric Transmission 5 (MODTRAN®5) is given. In the past surface flux and radiance data calculated using MODTRAN®5 has been compared to data from the World Ozone and Ultraviolet Data Centre (WOUDC) archive, and measurements taken by the author at the Defence Academy of the UK. With the aid of spectral measurement equipment, new measurements have been made and compared with the radiance profiles produced by MODTRAN®5, including measurements made throughout both winter and summer months. Also discussed are the effects of scattering and absorption by different cloud types on the amount of radiation observed at the Earth's surface.

UV radiation induces CXCL5 expression in human skin.

PubMed

Reichert, Olga; Kolbe, Ludger; Terstegen, Lara; Staeb, Franz; Wenck, Horst; Schmelz, Martin; Genth, Harald; Kaever, Volkhard; Roggenkamp, Dennis; Neufang, Gitta

2015-04-01

CXCL5 has recently been identified as a mediator of UVB-induced pain in rodents. To compare and to extend previous knowledge of cutaneous CXCL5 regulation, we performed a comprehensive study on the effects of UV radiation on CXCL5 regulation in human skin. Our results show a dose-dependent increase in CXCL5 protein in human skin after UV radiation. CXCL5 can be released by different cell types in the skin. We presumed that, in addition to immune cells, non-immune skin cells also contribute to UV-induced increase in CXCL5 protein. Analysis of monocultured dermal fibroblasts and keratinocytes revealed that only fibroblasts but not keratinocytes displayed up regulated CXCL5 levels after UV stimulation. Whereas UV treatment of human skin equivalents, induced epidermal CXCL5 mRNA and protein expression. Up regulation of epidermal CXCL5 was independent of keratinocyte differentiation and keratinocyte-keratinocyte interactions in epidermal layers. Our findings provide first evidence on the release of CXCL5 in UV-radiated human skin and the essential role of fibroblast-keratinocyte interaction in the regulation of epidermal CXCL5. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

An Estimate of Changes in the Sun's Total Irradiance Caused by UV Irradiance Variations from 1874 to 1988

NASA Technical Reports Server (NTRS)

Lean, J.

1990-01-01

Enhanced emission from bright solar faculae is a source of significant variation in the sun's total irradiance. Relative to the emission from the quiet sun, facular emission is known to be considerably greater at UV wavelengths than at visible wavelengths. Determining the spectral dependence of facular emission is of interest for the physical insight this may provide to the origin of the sun's irradiance variations. It is also of interest because solar radiation at lambda less than 300 nm is almost totally absorbed in the Earth's atmosphere. Depending on the magnitude of the UV irradiance variations, changes in the sun's irradiance that penetrates to the Earth's surface may not be equivalent to total irradiance variations measured above the Earth's atmosphere. Using an empirical model of total irradiance variations which accounts separately for changes caused by bright faculae from those associated with dark sunspots, the contribution of UV irradiance variations to changes in the sun's total irradiance is estimated during solar cycles 12 to 21.

Line-profile and continuum variations of the contact binary SV Centauri

NASA Technical Reports Server (NTRS)

Rahe, J.; Drechsel, H.; Wargau, W.

1982-01-01

A total of five high and ten low dispersion UV spectra of the interacting contact binary SV Centauri obtained between 1979 and 1982 are analyzed. The low resolution observations cover the whole phase range, while a few selected phases were observed in high dispersion. The UV data were complemented with optical photometric and spectroscopic observations, in order to determine the tructure and absolute dimensions of the system. The profiles of prominent UV resonance and metastable lines undergo drastic changes with phase angle and time. Their overall appearance indicates relatively strong mass loss from the system, exhibiting pronounced variations of the stellar wind. The far UV continuum distribution suggests the presence of a luminous hot radiation source with maximum emission in the soft X-ray range, which is most apparently seen during the first quadrature phase, while it is weakest close to primary minimum. The case exchange and mass loss process as well as the evolutionary stage of SV Centauri are discussed.

Extrapolating Accelerated UV Weathering Data: Perspective From PVQAT Task Group 5 (Presentation)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, D.; Annigoni, E.; Ballion, A.

2015-02-01

Taskgroup 5 (TG5) is concerned with a accelerated aging standard incorporating factors including ultraviolet radiation, temperature, and moisture. Separate experiments are being conducted in support of a test standard via the regional sub-groups in Asia, Europe, and the United States. The authors will describe the objectives and timeline for the TG5 interlaboratory study being directed out of the USA. Qualitative preliminary data from the experiment is presented. To date, the encapsulation transmittance experiment has: replicated behaviors of fielded materials (including specimen location- and formulation additive-specific discoloration); demonstrated coupling between UV aging and temperature; demonstrated that degradation in EVA results frommore » UV- aging; and obtained good qualitative comparison between Xe and UVA-340 sources for EVA. To date, the encapsulation adhesion experiment (using the compressive shear test to quantify strength of attachment) has demonstrated that attachment strength can decrease drastically (>50%) with age; however, early results suggest significant factor (UV, T, RH) dependence. Much remains to be learned about adhesion.« less

Growth, bioconversion of isoflavones and probiotic properties of parent and subsequent passages of Lactobacillus upon ultraviolet radiation.

PubMed

Yeo, Siok-Koon; Liong, Min-Tze

2012-11-01

The objective of this study was to evaluate the effects of ultraviolet (UV) radiation (UVB; 90 J/m²) on growth, bioconversion of isoflavones and probiotic properties of parent and subsequent passages of L. casei FTDC 2113. UV radiation significantly enhanced (P < 0.05) the growth of parent cells in mannitol-soymilk fermented at 37°C for 24 h. This had led to an enhanced intracellular and extracellular β-glucosidase activity with a subsequent increase in bioconversion of isoflavones in mannitol-soymilk (P < 0.05). UV radiation also promoted (P < 0.05) the tolerance of parent cells towards acidic condition (pH 2 and 3) and intestinal bile salts (oxgall, taurocholic and cholic acid). In addition, parent treated cells also exhibited better (P < 0.05) adhesion ability to mucin and antimicrobial activity compared to that of the control. All these positive effects of UV radiation were only prevalent in the parent cells without inheritance by first, second and third passage of cells. Although temporary, our results suggested that UV radiation could enhance the bioactive and probiotic potentials of L. casei FTDC 2113, and thus could be applied for the production of probiotic products with enhanced bioactivity.