WorldWideScience

Sample records for surface uv levels

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-12-31

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-12-31

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

  3. Modification of rubber surface by UV surface grafting

    International Nuclear Information System (INIS)

    Shanmugharaj, A.M.; Kim, Jin Kuk; Ryu, Sung Hun

    2006-01-01

    Rubber surface is subjected to ultraviolet radiation (UV) in the presence of allylamine and radiation sensitizer benzophenone (BP). Fourier transform infrared spectral studies reveal the presence of allylamine on the surface. The presence of irregular needle shapes on the surface as observed in scanning electron micrographs also confirms the polymerized allylamine on the surface. Allylamine coatings have been further confirmed from atomic force microscopy (AFM) analysis. Thermogravimetric analysis (TGA) reveals that allylamine coating on the rubber surface lowers the thermal degradation rate. The contact angle between the water and rubber surface decreases for the modified rubber surface confirming the surface modification due to UV surface grafting

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

    Science.gov (United States)

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

    2015-12-01

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

  5. Ultrastructural changes of photodegradation of wood surfaces exposed to UV

    International Nuclear Information System (INIS)

    Kuo, M.L.; Hu, N.

    1991-01-01

    Red pine sapwood transverse and radial surfaces were exposed to ultraviolet (UV) light for 3 to 40 days. Effect of UV irradiation on ultrastructural changes of cell walls were studied by scanning (SEM) and transmission (TEM) electron microscopy. SEM study of transverse sections showed that during initial stages of UV irradiation, lignin in cell corners and in the compound middle lamellae was preferentially degraded and that the radial middle lamellae substained a greater rate of UV degradation than did the tangential middle lamellae. Massive cell wall degradation, as indicated by cell wall thinning, did not occur until surfaces were exposed to UV light for more than 10 days. TEM study of radial cell wall surfaces indicated that lignin lining the warty layer was removed by UV irradiation in 3 days and that warts were destroyed by a UV irradiation in 7 days. UV irradiation of cell wall surfaces produced a substantial amount of water-soluble degradation products. After 30 days of UV irradiation, the S3 layer was totally removed and revealed the very fragile S2 layer. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1986-05-01

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

  7. Enhanced UV exposure on a ski-field compared with exposures at sea level.

    Science.gov (United States)

    Allen, Martin; McKenzie, Richard

    2005-05-01

    Personal erythemal UV monitoring badges, which were developed to monitor the UV exposure of school children, were used to measure UV exposures received by one of the authors (MA) at the Mt Hutt ski-field, in New Zealand. These were then compared with measurements taken at the same times from a nearby sea level site in Christchurch city. The badges were designed to give instantaneous readings of erythemally-weighted (i.e., "sun burning") UV radiation and were cross-calibrated against meteorological grade UV instruments maintained by the National Institute of Water & Atmospheric Research (NIWA). All skiing and calibration days were clear and almost exclusively cloud free. It was found that the UV maxima for horizontal surfaces at the ski-field (altitude approximately 2 km) were 20-30% greater than at the low altitude site. Larger differences between the sites were observed when the sensor was oriented perpendicular to the sun. The personal doses of UV received by a sensor on the skier's lapel during two days of skiing activity were less than those received by a stationary detector on a horizontal surface near sea level. The exposures depended strongly on the time of year, and in mid-October the maximum UV intensity on the ski-field was 60% greater than in mid-September. The UV exposure levels experienced during skiing were smaller than the summer maxima at low altitudes.

  8. Surface Coating of Musa Brachycarpa Trunk Using UV-Radiation

    International Nuclear Information System (INIS)

    Danu, Sugiarto; Sumarni, Anik; Nurhadi, Agus; Puspita, Rita

    2000-01-01

    An experiment on UV-curing of surface coating of Musa brachycarpa was carried out using urethane acrylate polymer films. Radiation curable material was the mixture of urethane acrylate resin, tripropylene glycol diacrylate monomer (TPGDA) and radical photo initiator of 2,2-dimethyl -2-hydroxy acetophenone. The TPGDA concentrations in the mixture with urethane acrylate resin were 60; 70 and 80% weight, Whereas concentrations of photo initiator were varied at the level 1.5:2.0 and 2.5% by weight based on resin and monomer mixture. Irradiation was conducted by using 80 Watt/cm intensity UV-light at the conveyor speed of 2: 3 and 4 m/min. Analysis and film properties observed were IR spectrum, gel fraction, hardness, abrasion resistance, glossy and chemical, solvent and stain resistances. Films have good resistances against 1% sodium carbonate, 5% acetic acid, 50% alcohol, thinner and red, blue and black permanent marker, except against 10% sodium hydroxide and 10% sulfuric acid. Optimum condition was achieved at the photo initiator concentration level of 2% and conveyor speed of 3 m/min

  9. Facile Dry Surface Cleaning of Graphene by UV Treatment

    Science.gov (United States)

    Kim, Jin Hong; Haidari, Mohd Musaib; Choi, Jin Sik; Kim, Hakseong; Yu, Young-Jun; Park, Jonghyurk

    2018-05-01

    Graphene has been considered an ideal material for application in transparent lightweight wearable electronics due to its extraordinary mechanical, optical, and electrical properties originating from its ordered hexagonal carbon atomic lattice in a layer. Precise surface control is critical in maximizing its performance in electronic applications. Graphene grown by chemical vapor deposition is widely used but it produces polymeric residue following wet/chemical transfer process, which strongly affects its intrinsic electrical properties and limits the doping efficiency by adsorption. Here, we introduce a facile dry-cleaning method based on UV irradiation to eliminate the organic residues even after device fabrication. Through surface topography, Raman analysis, and electrical transport measurement characteristics, we confirm that the optimized UV treatment can recover the clean graphene surface and improve graphene-FET performance more effectively than thermal treatment. We propose our UV irradiation method as a systematically controllable and damage-free post process for application in large-area devices.

  10. Elevated level of polysaccharides in a high level UV-B tolerant cell ...

    African Journals Online (AJOL)

    Jane

    2011-04-26

    Apr 26, 2011 ... A cell line of Bupleurum scorzonerifolium Willd with high level ... mechanisms to repair UV-induced damages via repairing ... for treatment or prevention of solar radiation. ..... working as both UV-B absorbing compounds and.

  11. Extensive reduction of surface UV radiation since 1750 in world's populated regions

    Directory of Open Access Journals (Sweden)

    M. M. Kvalevåg

    2009-10-01

    Full Text Available Human activity influences a wide range of components that affect the surface UV radiation levels, among them ozone at high latitudes. We calculate the effect of human-induced changes in the surface erythemally weighted ultra-violet radiation (UV-E since 1750. We compare results from a radiative transfer model to surface UV-E radiation for year 2000 derived by satellite observations (from Total Ozone Mapping Spectroradiometer and to ground based measurements at 14 sites. The model correlates well with the observations; the correlation coefficients are 0.97 and 0.98 for satellite and ground based measurements, respectively. In addition to the effect of changes in ozone, we also investigate the effect of changes in SO2, NO2, the direct and indirect effects of aerosols, albedo changes and aviation-induced contrails and cirrus. The results show an increase of surface UV-E in polar regions, most strongly in the Southern Hemisphere. Furthermore, our study also shows an extensive surface UV-E reduction over most land areas; a reduction up to 20% since 1750 is found in some industrialized regions. This reduction in UV-E over the industrial period is particularly large in highly populated regions.

  12. UV SURFACE ENVIRONMENT OF EARTH-LIKE PLANETS ORBITING FGKM STARS THROUGH GEOLOGICAL EVOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Rugheimer, S.; Sasselov, D. [Harvard Smithsonian Center for Astrophysics, 60 Garden st., 02138 MA Cambridge (United States); Segura, A. [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, México (Mexico); Kaltenegger, L., E-mail: srugheimer@cfa.harvard.edu [Carl Sagan Institute, Cornell University, Ithaca, NY 14853 (United States)

    2015-06-10

    The UV environment of a host star affects the photochemistry in the atmosphere, and ultimately the surface UV environment for terrestrial planets and therefore the conditions for the origin and evolution of life. We model the surface UV radiation environment for Earth-sized planets orbiting FGKM stars in the circumstellar Habitable Zone for Earth through its geological evolution. We explore four different types of atmospheres corresponding to an early-Earth atmosphere at 3.9 Gyr ago and three atmospheres covering the rise of oxygen to present-day levels at 2.0 Gyr ago, 0.8 Gyr ago, and modern Earth. In addition to calculating the UV flux on the surface of the planet, we model the biologically effective irradiance, using DNA damage as a proxy for biological damage. We find that a pre-biotic Earth (3.9 Gyr ago) orbiting an F0V star receives 6 times the biologically effective radiation as around the early Sun and 3520 times the modern Earth–Sun levels. A pre-biotic Earth orbiting GJ 581 (M3.5 V) receives 300 times less biologically effective radiation, about 2 times modern Earth–Sun levels. The UV fluxes calculated here provide a grid of model UV environments during the evolution of an Earth-like planet orbiting a range of stars. These models can be used as inputs into photo-biological experiments and for pre-biotic chemistry and early life evolution experiments.

  13. UV SURFACE ENVIRONMENT OF EARTH-LIKE PLANETS ORBITING FGKM STARS THROUGH GEOLOGICAL EVOLUTION

    International Nuclear Information System (INIS)

    Rugheimer, S.; Sasselov, D.; Segura, A.; Kaltenegger, L.

    2015-01-01

    The UV environment of a host star affects the photochemistry in the atmosphere, and ultimately the surface UV environment for terrestrial planets and therefore the conditions for the origin and evolution of life. We model the surface UV radiation environment for Earth-sized planets orbiting FGKM stars in the circumstellar Habitable Zone for Earth through its geological evolution. We explore four different types of atmospheres corresponding to an early-Earth atmosphere at 3.9 Gyr ago and three atmospheres covering the rise of oxygen to present-day levels at 2.0 Gyr ago, 0.8 Gyr ago, and modern Earth. In addition to calculating the UV flux on the surface of the planet, we model the biologically effective irradiance, using DNA damage as a proxy for biological damage. We find that a pre-biotic Earth (3.9 Gyr ago) orbiting an F0V star receives 6 times the biologically effective radiation as around the early Sun and 3520 times the modern Earth–Sun levels. A pre-biotic Earth orbiting GJ 581 (M3.5 V) receives 300 times less biologically effective radiation, about 2 times modern Earth–Sun levels. The UV fluxes calculated here provide a grid of model UV environments during the evolution of an Earth-like planet orbiting a range of stars. These models can be used as inputs into photo-biological experiments and for pre-biotic chemistry and early life evolution experiments

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

    International Nuclear Information System (INIS)

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

    1997-01-01

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

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

    International Nuclear Information System (INIS)

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

    1986-01-01

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

  16. Assessment of interplay between UV wavelengths, material surfaces and food residues in open surface hygiene validation

    DEFF Research Database (Denmark)

    Abban, Stephen; Jakobsen, Mogens; Jespersen, Lene

    2014-01-01

    The use of UV-visible radiation for detecting invisible residue on different surfaces as a means of validating cleanliness was investigated. Wavelengths at 365, 395, 435, 445, 470 and 490 nm from a monochromator were used to detect residues of beef, chicken, apple, mango and skim milk. These were....... It is important when UV-systems are used as real-time tools for assessing cleanliness of surfaces that the surface materials being illuminated are taken into account in the choice of lamp wavelength, in addition to expected residue. This will ensure higher confidence in results during the use of UV-light for real...

  17. Effect of remote clouds on surface UV irradiance

    Energy Technology Data Exchange (ETDEWEB)

    Deguenther, M.; Meerkoetter, R. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Wessling (Germany). Inst. fuer Physik der Atmosphaere

    2000-06-01

    Clouds affect local surface UV irradiance, even if the horizontal distance from the radiation observation site amounts to several kilometers. In order to investigate this effect, which we call remote clouds effect, a 3-dimensional radiative transfer model is applied. Assuming the atmosphere is subdivided into a quadratic based sector and its surrounding, we quantify the influence of changing cloud coverage within this surrounding from 0% to 100% on surface UV irradiance at the sector center. To work out this remote clouds influence as a function of sector base size, we made some calculations for different sizes between 10 km x 10 km and 100 km x 100 km. It appears that in the case of small sectors (base size {<=}20 km x 20 km) the remote clouds effect is highly variable: Depending on cloud structure, solar zenith angle and wavelength, the surface UV irradiance may be enhanced up to 15% as well as reduced by more than 50%. In contrast, for larger sectors it is always the case that enhancements become smaller by 5% if sector base size exceeds 60 km x 60 km. However, these values are upper estimates of the remote cloud effects and they are found only for special cloud structures. Since these structures might occur but cannot be regarded as typical, different satellite observed cloud formations (horizontal resolution about 1 km x 1 km) have also been investigated. For these more common cloud distributions we find remote cloud effects to be distinctly smaller than the corresponding upper estimates, e.g., for a sector with base size of 25 km x 25 km the surface UV irradiance error due to ignoring the actual remote clouds and replacing their influence with periodic horizontal boundary conditions is less than 3%, whereas the upper estimate of remote clouds effect would suggest an error close to 10%. (orig.)

  18. Planar UV excilamp excited by a surface barrier discharge

    Energy Technology Data Exchange (ETDEWEB)

    Guivan, N N [Department of Quantum Electronics, Uzhgorod National University, Pidgirna 46, Uzhgorod 88000 (Ukraine); Janca, J [Department of Physical Electronics, Masaryk University, Kotlarska 2, Brno 61137 (Czech Republic); Brablec, A [Department of Physical Electronics, Masaryk University, Kotlarska 2, Brno 61137 (Czech Republic); Stahel, P [Department of Physical Electronics, Masaryk University, Kotlarska 2, Brno 61137 (Czech Republic); SlavIcek, P [Department of Physical Electronics, Masaryk University, Kotlarska 2, Brno 61137 (Czech Republic); Shimon, L L [Department of Quantum Electronics, Uzhgorod National University, Pidgirna 46, Uzhgorod 88000 (Ukraine)

    2005-09-07

    In this paper, the typical characteristics of a planar excilamp based on KrCl* and XeCl* exciplex molecules are presented. The excitation of the working mixture Kr/Xe/Cl{sub 2} is realized by means of the surface barrier discharge at pressures of 0.1-1 bar. The following properties are measured and discussed: spectra emitted by the plasma in the UV/VIS/NIR spectral range, intensity of emitted light versus total pressure in the discharge, the composition of the working mixture and the power of emitted light. The radiation power versus input electric power, and space distribution of the emitted light including basic electrical parameters of the discharge were also measured. It was shown that the characteristic power of UV radiation emitted in the spectral range 200-400 nm is about 6 mW cm{sup -2} while the efficiency could be about 8%.

  19. Leaf surface wax is a source of plant methane formation under UV radiation and in the presence of oxygen

    DEFF Research Database (Denmark)

    Bruhn, Dan; Mikkelsen, Teis Nørgaard; Rolsted, M. M. M.

    2014-01-01

    to this, we demonstrated that the UV radiation-induced CH4 emission is independent of leaf area index above unity. Further, we observed that the presence of O2 in the atmosphere was necessary for achieving the highest rates of CH4 emission. Methane formation from leaf surface wax is supposedly a two...... investigated the potential of the leaf surface wax itself as a source of UV radiationinduced leaf aerobic CH4 formation. Isolated leaf surface wax emitted CH4 at substantial rates in response to UV radiation. This discovery has implications for how the phenomenon should be scaled to global levels. In relation...

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

    International Nuclear Information System (INIS)

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

    2000-01-01

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

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

    International Nuclear Information System (INIS)

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

    2006-01-01

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

  2. A comparison of UV surface brightness and HI surface densities for spiral galaxies

    International Nuclear Information System (INIS)

    Federman, S.R.; Strom, C.

    1990-01-01

    Shaya and Federman (1987) suggested that the ambient ultraviolet flux at 1000 A permeating a spiral galaxy controls the neutral hydrogen (HI) surface density in the galaxy. They found that the atomic envelopes surrounding small molecular clouds, because of their great number, provide the major contribution to the HI surface density over the stellar disk. The increase in HI surface density with later Hubble types was ascribed to the stronger UV fields from more high-mass stars in later Hubble types. These hypotheses are based on the observations of nearby diffuse interstellar clouds, which show a sharp atomic-to-molecular transition (Savage et al. 1977), and on the theoretical framework introduced by Federman, Glassgold, and Kwan (1979). Atomic envelopes around interstellar clouds in the solar neighborhood arise when a steady state is reached between photodissociation of H2 and the formation of H2 on grains. The photodissociation process involves photons with wavelengths between 912 A and 1108 A. Shaya and Federman used H-alpha flux as an approximate measure for the far UV flux and made their comparisons based on averages over Hubble type. Here, researchers compare, on an individual basis, UV data obtained with space-borne and balloon-borne instruments for galaxies with measurements of HI surface density (Warmels 1988a, b). The comparisons substantiate the conclusion of Shaya and Federman that the far UV field controls the HI content of spiral galaxies

  3. A new method for estimating UV fluxes at ground level in cloud-free conditions

    Science.gov (United States)

    Wandji Nyamsi, William; Pitkänen, Mikko R. A.; Aoun, Youva; Blanc, Philippe; Heikkilä, Anu; Lakkala, Kaisa; Bernhard, Germar; Koskela, Tapani; Lindfors, Anders V.; Arola, Antti; Wald, Lucien

    2017-12-01

    A new method has been developed to estimate the global and direct solar irradiance in the UV-A and UV-B at ground level in cloud-free conditions. It is based on a resampling technique applied to the results of the k-distribution method and the correlated-k approximation of Kato et al. (1999) over the UV band. Its inputs are the aerosol properties and total column ozone that are produced by the Copernicus Atmosphere Monitoring Service (CAMS). The estimates from this new method have been compared to instantaneous measurements of global UV irradiances made in cloud-free conditions at five stations at high latitudes in various climates. For the UV-A irradiance, the bias ranges between -0.8 W m-2 (-3 % of the mean of all data) and -0.2 W m-2 (-1 %). The root mean square error (RMSE) ranges from 1.1 W m-2 (6 %) to 1.9 W m-2 (9 %). The coefficient of determination R2 is greater than 0.98. The bias for UV-B is between -0.04 W m-2 (-4 %) and 0.08 W m-2 (+13 %) and the RMSE is 0.1 W m-2 (between 12 and 18 %). R2 ranges between 0.97 and 0.99. This work demonstrates the quality of the proposed method combined with the CAMS products. Improvements, especially in the modeling of the reflectivity of the Earth's surface in the UV region, are necessary prior to its inclusion into an operational tool.

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

    NARCIS (Netherlands)

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

    2002-01-01

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

  5. Atmospheric Constraints on the Surface UV Environment of Mars at 3.9 Ga Relevant to Prebiotic Chemistry

    Science.gov (United States)

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

    2017-08-01

    Recent findings suggest that Mars may have been a clement environment for the emergence of life and may even have compared favorably to Earth in this regard. These findings have revived interest in the hypothesis that prebiotically important molecules or even nascent life may have formed on Mars and been transferred to Earth. UV light plays a key role in prebiotic chemistry. Characterizing the early martian surface UV environment is key to understanding how Mars compares to Earth as a venue for prebiotic chemistry. Here, we present two-stream, multilayer calculations of the UV surface radiance on Mars at 3.9 Ga to constrain the surface UV environment as a function of atmospheric state. We explore a wide range of atmospheric pressures, temperatures, and compositions that correspond to the diversity of martian atmospheric states consistent with available constraints. We include the effects of clouds and dust. We calculate dose rates to quantify the effect of different atmospheric states on UV-sensitive prebiotic chemistry. We find that, for normative clear-sky CO2-H2O atmospheres, the UV environment on young Mars is comparable to young Earth. This similarity is robust to moderate cloud cover; thick clouds (τcloud ≥ 100) are required to significantly affect the martian UV environment, because cloud absorption is degenerate with atmospheric CO2. On the other hand, absorption from SO2, H2S, and dust is nondegenerate with CO2, meaning that, if these constituents build up to significant levels, surface UV fluence can be suppressed. These absorbers have spectrally variable absorption, meaning that their presence affects prebiotic pathways in different ways. In particular, high SO2 environments may admit UV fluence that favors pathways conducive to abiogenesis over pathways unfavorable to it. However, better measurements of the spectral quantum yields of these pathways are required to evaluate this hypothesis definitively.

  6. Surface coatings of unsaturated polyester resin Kamper wood (Dry obalan ops spp.) by using UV radiation

    International Nuclear Information System (INIS)

    Sugiarto Danu; Yusuf Sudo Hadi; Novi Eka Putri

    1999-01-01

    Kamper wood (Dryobalanops spp.) has high contribution in wood working industry and most of them need surface coating process. Radiation curing of surface coating, especially the use of ultra-violet (UV) light have potential to give contribution in the wood finishing. The experiment on surface coating of kamper wood has been conducted by using UV-radiation. Unsaturated polyester resin with the commercial name of Yucalac type 157 was used as coating materials after being added with styrene monomer, some fillers and radical photoinitiator of 2-hydroxy-2-2-methyl-l- phenyl propanone. Four photoinitiator concentration levels of 1.5 ; 2 ; 2.5 and 3 % by weight of resin were used. The coating materials were coated onto the wood panel samples by using high pressure sprayer. The wood samples were then exposed to irradiation by using 80 Watts/cm UV-source with variable conveyor speed of 3 ; 4 ; 5 and 5.8 m/min. Formulation of coating materials, pendulum hardness, adhesion, and gloss of cured films were evaluated

  7. TiO2 micro-nano-hybrid surface to alleviate biological aging of UV-photofunctionalized titanium.

    Science.gov (United States)

    Iwasa, Fuminori; Tsukimura, Naoki; Sugita, Yoshihiko; Kanuru, Rajita Kodali; Kubo, Katsutoshi; Hasnain, Hafiz; Att, Wael; Ogawa, Takahiro

    2011-01-01

    Bioactivity and osteoconductivity of titanium degrade over time after surface processing. This time-dependent degradation is substantial and defined as the biological aging of titanium. UV treatment has shown to reactivate the aged surfaces, a process known as photofunctionalization. This study determined whether there is a difference in the behavior of biological aging for titanium with micro-nano-hybrid topography and titanium with microtopography alone, following functionalization. Titanium disks were acid etched to create micropits on the surface. Micro-nano-hybrid surfaces were created by depositioning 300-nm diameter TiO(2) nodules onto the micropits using a previously established self-assembly protocol. These disks were stored for 8 weeks in the dark to allow sufficient aging, then treated with UV light for 48 hours. Rat bone marrow-derived osteoblasts were cultured on fresh disks (immediately after UV treatment), 3-day-old disks (disks stored for 3 days after UV treatment), and 7-day- old disks. The rates of cell attachment, spread, proliferation, and levels of alkaline phosphatase activity, and calcium deposition were reduced by 30%-50% on micropit surfaces, depending on the age of the titanium. In contrast, 7-day-old hybrid surfaces maintained equivalent levels of bioactivity compared with the fresh surfaces. Both micropit and micro-nano-hybrid surfaces were superhydrophilic immediately after UV treatment. However, after 7 days, the micro-nano- hybrid surfaces became hydrorepellent, while the micropit surfaces remained hydrophilic. The sustained bioactivity levels of the micro-nano-hybrid surfaces were nullified by treating these surfaces with Cl(-)anions. A thin TiO(2) coating on the micropit surface without the formation of nanonodules did not result in the prevention or alleviation of the time-dependent decrease in biological activity. In conclusion, the micro-nano-hybrid titanium surfaces may slow the rate of time-dependent degradation of titanium

  8. Surface properties of UV irradiated PC–TiO{sub 2} nanocomposite film

    Energy Technology Data Exchange (ETDEWEB)

    Jaleh, B., E-mail: bkjaleh@yahoo.com; Shahbazi, N.

    2014-09-15

    Highlights: • Production of PC–TiO{sub 2} nanocomposite films. • Fully characterization of PC–TiO{sub 2} nanocomposite films. • Influence of UV irradiation on surface properties and hardness of PC–TiO{sub 2} nanocomposite film. - Abstract: In this work, polycarbonate–TiO{sub 2} nanocomposite films were prepared with two different percentages. The structure of samples were studied by X-ray diffraction. Thermal stability of the nanocomposites was studied by thermogravimetric analysis (TGA). The polycarbonate and polycarbonate–TiO{sub 2} nanocomposite films were exposed by UV light at different irradiation times. The effects of UV irradiation on the surface properties of samples have been studied by different characterization techniques, viz. scanning electron microscopy (SEM), FTIR spectroscopy, X-ray photoelectron spectroscopy (XPS), contact angle measurement and Vickers microhardness tester. Hydrophilicity and surface energy of UV treated samples varied depending on UV irradiation time. TGA curves showed that nanocomposite films have higher resistance to thermal degradation compared to polycarbonate. XPS analysis shows that surface of samples become more oxidized due to UV irradiation. For nanocomposite film, the smallest contact angle was observed in association with the longest UV irradiation time. The contact angle significantly decreased from 90° to 12° after 15 h of UV irradiation. It is observed that the hardness of the nanocomposite films increases after UV irradiation.

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

    International Nuclear Information System (INIS)

    Deckmyn, G.; Impens, I.

    1999-01-01

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

  10. Aerosols and surface UV products form Ozone Monitoring Instrument observations: An overview

    NARCIS (Netherlands)

    Torres, O.; Tanskanen, A.; Veihelmann, B.; Ahn, C.; Braak, R.; Bhartia, P.K.; Veefkind, J.P.; Levelt, P.F.

    2007-01-01

    We present an overview of the theoretical and algorithmic aspects of the Ozone Monitoring Instrument (OMI) aerosol and surface UV algorithms. Aerosol properties are derived from two independent algorithms. The nearUV algorithm makes use of OMI observations in the 350-390 nm spectral region to

  11. Pollution patterns and underlying relationships of benzophenone-type UV-filters in wastewater treatment plants and their receiving surface water.

    Science.gov (United States)

    Wu, Ming-Hong; Li, Jian; Xu, Gang; Ma, Luo-Dan; Li, Jia-Jun; Li, Jin-Song; Tang, Liang

    2018-05-15

    The environmental behaviors of emerging pollutants, benzophenone-type UV filters (BP-UV filters) and their derivatives were investigated in four wastewater treatment plants (WWTPs), and their receiving surface waters in Shanghai. The concentration level of selected BP-UV filters in the WWTPs was detected from ngL -1 to μgL -1 . BP (621-951ngL -1 ) and BP-3 (841-1.32 × 10 3 ngL -1 ) were the most abundant and highest detection frequency individuals among the target BP-UV filters in influents, whereas BP (198-400ngL -1 ), BP-4 (93.3-288ngL -1 ) and BP-3 (146-258ngL -1 ) were predominant in effluents. BP-UV filters cannot be completely removed and the total removal efficiency varied widely (-456% to 100%) during the treatment process. It can be inferred that the usage of BP and BP-3 are higher than other BP-UV filters in the study area. The lowest and highest levels were BP-2 (ND-7.66ngL -1 ) and BP-3 (68.5-5.01 × 10 3 ng L -1 ) in the receiving surface water, respectively. Interestingly, the seasonal variation of BP-3 is larger than those of other BP-UV filters in surface water from Shanghai. There is no obvious pollution pattern of BP-UV filters in the surface water from the cosmetic factory area. The correlation analysis of BP-UV filters between WWTPs effluents and nearby downstream water samples suggested that BP-UV filters emitted from some WWTPs might be the main source of receiving surface water. Preliminary risk assessment indicated that the levels of BP-UV filters detected by the effluent posed medium to high risk to fish as well as other aquatic organisms. Copyright © 2018 Elsevier Inc. All rights reserved.

  12. UV irradiation assisted growth of ZnO nanowires on optical fiber surface

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Bo; Shi, Tielin; Liao, Guanglan; Li, Xiaoping; Huang, Jie; Zhou, Temgyuan; Tang, Zirong, E-mail: zirong@mail.hust.edu.cn

    2017-06-01

    Highlights: • A new fabrication process combined a hydrothermal process with UV irradiation from optical fiber is developed. • The growth of ZnO nanowires is efficient in the utilization of UV light. • A novel hybrid structure which integrates ZnO nanowires on optical fiber surface is synthesized. • The UV assisted growth of ZnO nanowires shows preferred orientation and better quality. • A mechanism of growing ZnO nanowires under UV irradiation is proposed. - Abstract: In this paper, a novel approach was developed for the enhanced growth of ZnO nanowires on optical fiber surface. The method combined a hydrothermal process with the efficient UV irradiation from the fiber core, and the effects of UV irradiation on the growth behavior of ZnO nanowires were investigated. The results show that UV irradiation had great effects on the preferred growth orientation and the quality of the ZnO nanowires. The crystallization velocity along the c-axis would increase rapidly with the increase of the irradiation power, while the growth process in the lateral direction was marginally affected by the irradiation. The structure of ZnO nanowires also shows less oxygen vacancy with UV irradiation of higher power. The developed approach is applicable for the efficient growth of nanowires on the fiber surface, and the ZnO nanowires/optical fiber hybrid structures have great potentials for a wide variety of applications such as optical fiber sensors and probes.

  13. Surface passivation process of compound semiconductor material using UV photosulfidation

    Science.gov (United States)

    Ashby, Carol I. H.

    1995-01-01

    A method for passivating compound semiconductor surfaces by photolytically disrupting molecular sulfur vapor with ultraviolet radiation to form reactive sulfur which then reacts with and passivates the surface of compound semiconductors.

  14. The effects of altered levels of UV-B radiation on an Antarctic grass and lichen

    NARCIS (Netherlands)

    Lud, D.; Huiskes, A.H.L.; Moerdijk-Poortvliet, T.C.W.; Rozema, J.J.

    2001-01-01

    We report a long-term experiment on the photosynthetic response of natural vegetation of Deschampsia antarctica (Poaceae) and Turgidosculum complicatulum (Lichenes) to altered UV-B levels on Leonie Island, Antarctica. UV-B above the vegetation was reduced by filter screens during two seasons. Half

  15. Retrieval of Surface Ozone from UV-MFRSR Irradiances using Deep Learning

    Science.gov (United States)

    Chen, M.; Sun, Z.; Davis, J.; Zempila, M.; Liu, C.; Gao, W.

    2017-12-01

    High concentration of surface ozone is harmful to humans and plants. USDA UV-B Monitoring and Research Program (UVMRP) uses Ultraviolet (UV) version of Multi-Filter Rotating Shadowband Radiometer (UV-MFRSR) to measure direct, diffuse, and total irradiances every three minutes at seven UV channels (i.e. 300, 305, 311, 317, 325, 332, and 368 nm channels with 2 nm full width at half maximum). Based on the wavelength dependency of aerosol optical depths, there have been plenty of literatures exploring retrieval methods of total column ozone from UV-MFRSR measurements. However, few has explored the retrieval of surface ozone. The total column ozone is the integral of the multiplication of ozone concentration (varying by height and time) and cross section (varying by wavelength and temperature) over height. Because of the distinctive values of ozone cross section in the UV region, the irradiances at seven UV channels have the potential to resolve the ozone concentration at multiple vertical layers. If the UV irradiances at multiple time points are considered together, the uncertainty or the vertical resolution of ozone concentrations can be further improved. In this study, the surface ozone amounts at the UVMRP station located at Billings, Oklahoma are estimated from the adjacent (i.e. within 200 miles) US Environmental Protection Agency (EPA) surface ozone observations using the spatial analysis technique. Then, the (direct normal) irradiances of UVMRP at one or more time points as inputs and the corresponding estimated surface ozone from EPA as outputs are fed into a pre-trained (dense) deep neural network (DNN) to explore the hidden non-linear relationship between them. This process could improve our understanding of their physical/mathematical relationship. Finally, the optimized DNN is tested with the preserved 5% of the dataset, which are not used during training, to verify the relationship.

  16. Effect of UV/ozone treatment on the nanoscale surface properties of gold implanted polyethylene

    Energy Technology Data Exchange (ETDEWEB)

    Kisić, Danilo; Nenadović, Miloš [INS Vinca, Laboratory of Atomic Physics, University of Belgrade, Mike Alasa 12-14, 11001 Belgrade (Serbia); Štrbac, Svetlana [ICTM Institute of Electrochemistry, University of Belgrade, Njegoseva 12, 11001 Belgrade (Serbia); Adnadjević, Borivoj [Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, 11158 Belgrade (Serbia); Rakočević, Zlatko, E-mail: zlatkora@vinca.rs [INS Vinca, Laboratory of Atomic Physics, University of Belgrade, Mike Alasa 12-14, 11001 Belgrade (Serbia)

    2014-07-01

    The effect of ultraviolet (UV) ozone treatment on the surface properties of gold implanted high density polyethylene (HDPE) was investigated at a nanoscale using Atomic Force Microscopy (AFM). HDPE samples were modified by the implantation of gold ions at a dose of 5 × 10{sup 15} ions/cm{sup 2}, using energies of 50, 100, 150, and 200 keV, and subsequently treated with UV/ozone. AFM surface topography images revealed that after UV/ozone treatment, the surface roughness of all Au/HDPE samples increased, while Power Spectral Density function increased only for samples implanted using higher energies, with a maximum for 150 keV. The chemical surface composition was homogenous in all cases, which was evidenced by the appearance of single peaks in the histograms obtained from the phase AFM images. For UV/ozone treated samples, the shift of the peaks positions in the histograms to the higher values of the phase lag with respect to untreated ones indicated the decrease of surface hardness. Besides, a significant change of fractal dimension of surface grains is observed after UV/ozone treatment.

  17. Design of UV-absorbing PVDF membrane via surface-initiated AGET ATRP

    Science.gov (United States)

    Dong, Li; Liu, Xiangdong; Xiong, Zhengrong; Sheng, Dekun; Zhou, Yan; Lin, Changhong; Yang, Yuming

    2018-03-01

    Herein, PVDF membranes with excellent UV-absorbing property were first synthesized through grafting the polymerizable low-molecular-weight organic UV-absorber 2-hydroxy-4-(3-methacryloxy-2-hydroxylpropoxy) benzophenone (BPMA) onto α-bromoester-functionalized PVDF membranes via the surface-initiated activator generated by electron transfer atom transfer radical polymerization (SI-AGET ATRP). The surface initiators were immobilized by the reaction between 2-bromoisobutyryl bromide (BIBB) and the hydroxylated PVDF membranes. PVDF-g-PBPMA membranes with different grafting densities were obtained by tuning the polymerization time and the modified membranes were characterized by 1H-NMR, FT-IR, XPS, SEM, UV-vis Spectrophotometer, TGA and DSC. The experimental results indicated that PBPMA chains were successfully introduced onto PVDF membranes. Most importantly, the PVDF-g-PBPMA membranes exhibited outstanding UV-shielding property. UV-vis transmittance spectra showed that most UV light below 360 nm could be absorbed by PVDF-g-PBPMA membranes and the whole UV light region (200-400 nm) can be blocked with the reaction time increased.

  18. Investigation of static and dynamic wetting transitions of UV responsive tunable wetting surfaces

    International Nuclear Information System (INIS)

    Pant, Reeta; Singha, Subhash; Bandyopadhyay, Aritra; Khare, Krishnacharya

    2014-01-01

    Ultraviolet (UV) radiation responsive surfaces, with tunable wetting properties, are fabricated by spin casting polystyrene/titania nanocomposite dispersion in tetrahydrofuran on silicon substrates. The prepared samples are found hydrophilic due to the presence of the water miscible solvent. Upon annealing, as the solvent evaporates, samples become superhydrophobic due to presence of hydrophobic polystyrene and formation of nano and micro scale surface roughness due to titania nanoparticles. Effect of different annealing temperatures and time on resulting wettability is investigated. Photocatalytic property of titania is exploited to make transition from superhydrophobic to hydrophilic state upon UV exposure. Subsequently, upon annealing again at elevated temperatures for sufficient time, the UV exposed hydrophilic samples recover their superhydrophobicity showing transition from hydrophilic to superhydrophobic state. Detailed static and dynamic study of these reversible transitions, between superhydrophobic and hydrophilic states, due to UV exposure and annealing is presented in this article.

  19. Wettability modification of human tooth surface by water and UV and electron-beam radiation

    International Nuclear Information System (INIS)

    Tiznado-Orozco, Gaby E.; Reyes-Gasga, José; Elefterie, Florina; Beyens, Christophe; Maschke, Ulrich; Brès, Etienne F.

    2015-01-01

    The wettability of the human tooth enamel and dentin was analyzed by measuring the contact angles of a drop of distilled water deposited on the surface. The samples were cut along the transverse and longitudinal directions, and their surfaces were subjected to metallographic mirror-finish polishing. Some samples were also acid etched until their microstructure became exposed. Wettability measurements of the samples were done in dry and wet conditions and after ultraviolet (UV) and electron beam (EB) irradiations. The results indicate that water by itself was able to increase the hydrophobicity of these materials. The UV irradiation momentarily reduced the contact angle values, but they recovered after a short time. EB irradiation raised the contact angle and maintained it for a long time. Both enamel and dentin surfaces showed a wide range of contact angles, from approximately 10° (hydrophilic) to 90° (hydrophobic), although the contact angle showed more variability on enamel than on dentin surfaces. Whether the sample's surface had been polished or etched did not influence the contact angle value in wet conditions. - Highlights: • Human tooth surface wettability changes in dry/wet and UV/EB radiation conditions. • More variability in contact angle is observed on enamel than on dentin surfaces. • Water by itself increases the hydrophobicity of the human tooth surface. • UV irradiation reduces momentarily the human tooth surface hydrophobicity. • EB irradiation increases and maintains the hydrophobicity for a long time

  20. Wettability modification of human tooth surface by water and UV and electron-beam radiation

    Energy Technology Data Exchange (ETDEWEB)

    Tiznado-Orozco, Gaby E., E-mail: gab0409@gmail.com [UMET, Bâtiment C6, Université de Lille 1, Sciences et Technologies, 59650 Villeneuve d' Ascq (France); Unidad Académica de Odontología, Universidad Autónoma de Nayarit, Edificio E7, Ciudad de la Cultura “Amado Nervo”, C.P. 63190 Tepic, Nayarit (Mexico); Reyes-Gasga, José, E-mail: jreyes@fisica.unam.mx [UMET, Bâtiment C6, Université de Lille 1, Sciences et Technologies, 59650 Villeneuve d' Ascq (France); Instituto de Física, UNAM, Circuito de la Investigación s/n, Ciudad Universitaria, 04510 Coyoacan, México, D.F. (Mexico); Elefterie, Florina, E-mail: elefterie_florina@yahoo.com [UMET, Bâtiment C6, Université de Lille 1, Sciences et Technologies, 59650 Villeneuve d' Ascq (France); Beyens, Christophe, E-mail: christophe.beyens@ed.univ-lille1.fr [UMET, Bâtiment C6, Université de Lille 1, Sciences et Technologies, 59650 Villeneuve d' Ascq (France); Maschke, Ulrich, E-mail: Ulrich.Maschke@univ-lille1.fr [UMET, Bâtiment C6, Université de Lille 1, Sciences et Technologies, 59650 Villeneuve d' Ascq (France); Brès, Etienne F., E-mail: etienne.bres@univ-lille1.fr [UMET, Bâtiment C6, Université de Lille 1, Sciences et Technologies, 59650 Villeneuve d' Ascq (France)

    2015-12-01

    The wettability of the human tooth enamel and dentin was analyzed by measuring the contact angles of a drop of distilled water deposited on the surface. The samples were cut along the transverse and longitudinal directions, and their surfaces were subjected to metallographic mirror-finish polishing. Some samples were also acid etched until their microstructure became exposed. Wettability measurements of the samples were done in dry and wet conditions and after ultraviolet (UV) and electron beam (EB) irradiations. The results indicate that water by itself was able to increase the hydrophobicity of these materials. The UV irradiation momentarily reduced the contact angle values, but they recovered after a short time. EB irradiation raised the contact angle and maintained it for a long time. Both enamel and dentin surfaces showed a wide range of contact angles, from approximately 10° (hydrophilic) to 90° (hydrophobic), although the contact angle showed more variability on enamel than on dentin surfaces. Whether the sample's surface had been polished or etched did not influence the contact angle value in wet conditions. - Highlights: • Human tooth surface wettability changes in dry/wet and UV/EB radiation conditions. • More variability in contact angle is observed on enamel than on dentin surfaces. • Water by itself increases the hydrophobicity of the human tooth surface. • UV irradiation reduces momentarily the human tooth surface hydrophobicity. • EB irradiation increases and maintains the hydrophobicity for a long time.

  1. Surface contamination to UV-curable acrylates in the furniture and parquet industry.

    Science.gov (United States)

    Surakka, J; Lindh, T; Rosén, G; Fischer, T

    2001-03-01

    Surface contamination to ultraviolet radiation curable coatings (UV coatings), used increasingly in the parquet and furniture industry, is a matter of concern as a source for skin contamination. UV coatings contain chemically and biologically reactive acrylates, well known as skin contact irritants and sensitizers. Surface contamination may spread secondarily to equipment and other unexpected areas even outside the workplace. Yet, studies concerning this type of contamination are lacking due to lack of suitable sampling methods. Surface contamination of the work environment with risk for skin exposure to UV coating was measured employing a quantitative adhesive tape sampling method developed for this purpose. A pilot study was first performed at three workplaces to evaluate the contamination. In the main study, we wanted to locate and identify in detail the surface contamination of areas where problems exist, and to determine the extent of the problem. Measurements were performed at seven workplaces on two separate workdays (round 1 and 2) within a six-month period. Samples were collected from the workplaces based on the video monitoring of skin contact frequency with the surfaces and categorized into three groups to analyze risk. The pilot study indicated that surface contamination to TPGDA containing UV coatings was common, found in 76 percent of the surfaces, and varied with a maximum of 909 microg TPGDA 10 cm(-2) sampling area. In the main study TPGDA was found in 153 out of 196 collected samples (78.1%); for round one 78.1 percent (82 out of 105 samples) and for round two 78.0 percent (71 out of 91 samples). The average TPGDA mass on positive surface samples was on the first round 2,247 +/- 7,462 microg, and on the second round 2,960 +/- 4,590 microg. We conclude that surface contamination to uncured UV coatings at UV-curing lines is common and this involves a risk for harmful, unintentional skin exposure to acrylates.

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

    Science.gov (United States)

    1992-02-01

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

  3. Directional uv photoemission from (100) and (110) molybdenum surfaces

    DEFF Research Database (Denmark)

    Cinti, R. C.; Khoury, E. Al; Chakraverty, B. K.

    1976-01-01

    A study of the (100) and (110) molybdenum surfaces by directional photoemission spectroscopy is presented. Energy distribution spectra formed by photoelectrons emitted normal to the surfaces have been measured for photon energies between 10.2 and 21.2 eV. The results are discussed in terms of cal......-transition and surface-emission processes. Two extra structures are interpreted in terms of surface states or resonances: on the (100) surface, 0.5 eV below EF; on the (110) surface, 4.5 eV below EF in the s-d hybridization gap....... of calculated band structure within the framework of the K∥-conservation assumption. A good agreement is found between the main features of the experimental spectra and the emission expected from the band structure along the corresponding symmetry line in the Brillouin zone, assuming essentially direct...

  4. Modelling UV irradiances on arbitrarily oriented surfaces: effects of sky obstructions

    OpenAIRE

    Hess, M.; Koepke, P.

    2008-01-01

    A method is presented to calculate UV irradiances on inclined surfaces that additionally takes into account the influence of sky obstructions caused by obstacles such as mountains, houses, trees, or umbrellas. With this method it is thus possible to calculate the impact of UV radiation on biological systems, such as, for instance, the human skin or eye, in any natural or artificial environment. The method, which consists of a combination of radiation models, is explained here and the accuracy...

  5. Colour Changes on the Surface of the Rock Materials Due to UV-A and UV-B Rays

    Science.gov (United States)

    Binal, Adil; Ayderman, Aykut; Sel, Aylin

    2015-04-01

    The colour of the rocks used in the current buildings, and historical monuments is an important parameter in architecture and engineering. In addition, engineering geologists use the colour in order to identify the weathering class of rock material. The main colour of the stone, especially, are affected by the mineral size, the colour of the primary minerals and matrix material, as well as the colour of the accessory minerals. Due to atmospheric effects, changes in the outer surface colour of the rocks used as siding materials occur with over time. Factors causing the colour change are carbon dioxide (CO2), ozone (O3), sulphate (SO2, SO3) and nitrate (NOx) from the atmosphere with aerosols as well as UV rays from the sun. There is no more work in the literature on colour changes caused by UV-A and UV-B rays. In this study, the effects of ultraviolet in the colour of the surfaces of basalt, limestone, ignimbrite, travertine and sandstone have been simulated with a new experimental device in the laboratory medium. Lutron colour analyser (RGB-1002) was used for the measurements of RGB colours. Colour differences between the beginning and end of tests were determined with the standard practice for calculation of colour tolerances and colour differences from instrumentally measured colour coordinates (ASTM D2244). As a result of the experiments performed, lighten that seem on dark-grey micritic limestone (colour change ratio, CCR: 17.06) and basalt samples (CCR: 8.24) become even visually noticeable. Black and red ignimbrite samples having high porosity were presented the lower rate of colour changes. Finally, colour darkening has been observed in the light-coloured travertine (CCR: 13.8) and sandstone samples (CCR: 20.99).

  6. TiO2 micro-nano-hybrid surface to alleviate biological aging of UV-photofunctionalized titanium

    Directory of Open Access Journals (Sweden)

    Iwasa F

    2011-06-01

    Full Text Available Fuminori Iwasa1, Naoki Tsukimura1, Yoshihiko Sugita1, Rajita Kodali Kanuru1, Katsutoshi Kubo1, Hafiz Hasnain1, Wael Att1,2, Takahiro Ogawa11Laboratory of Bone and Implant Sciences (LBIS, The Weintraub Center for Reconstructive Biotechnology, Division of Advanced Prosthodontics, Biomaterials and Hospital Dentistry, UCLA School of Dentistry, Los Angeles, CA, USA; 2Department of Prosthodontics, Dental School, Albert-Ludwigs University, Freiburg, GermanyAbstract: Bioactivity and osteoconductivity of titanium degrade over time after surface processing. This time-dependent degradation is substantial and defined as the biological aging of titanium. UV treatment has shown to reactivate the aged surfaces, a process known as photofunctionalization. This study determined whether there is a difference in the behavior of biological aging for titanium with micro-nano-hybrid topography and titanium with microtopography alone, following functionalization. Titanium disks were acid etched to create micropits on the surface. Micro-nano-hybrid surfaces were created by depositioning 300-nm diameter TiO2 nodules onto the micropits using a previously established self-assembly protocol. These disks were stored for 8 weeks in the dark to allow sufficient aging, then treated with UV light for 48 hours. Rat bone marrow–derived osteoblasts were cultured on fresh disks (immediately after UV treatment, 3-day-old disks (disks stored for 3 days after UV treatment, and 7-day-old disks. The rates of cell attachment, spread, proliferation, and levels of alkaline phosphatase activity, and calcium deposition were reduced by 30%–50% on micropit surfaces, depending on the age of the titanium. In contrast, 7-day-old hybrid surfaces maintained equivalent levels of bioactivity compared with the fresh surfaces. Both micropit and micro-nano-hybrid surfaces were superhydrophilic immediately after UV treatment. However, after 7 days, the micro-nano-hybrid surfaces became hydrorepellent

  7. Antioxidant responses in the polar marine sea-ice amphipod Gammarus wilkitzkii to natural and experimentally increased UV levels

    International Nuclear Information System (INIS)

    Krapp, Rupert H.; Bassinet, Thievery; Berge, Jorgen; Pampanin, Daniela M.; Camus, Lionel

    2009-01-01

    Polar marine surface waters are characterized by high levels of dissolved oxygen, seasonally intense UV irradiance and high levels of dissolved organic carbon. Therefore, the Arctic sea-ice habitat is regarded as a strongly pro-oxidant environment, even though its significant ice cover protects the ice-associated (=sympagic) fauna from direct irradiation to a large extent. In order to investigate the level of resistance to oxyradical stress, we sampled the sympagic amphipod species Gammarus wilkitzkii during both winter and summer conditions, as well as exposed specimens to simulated levels of near-natural and elevated levels of UV irradiation. Results showed that this amphipod species possessed a much stronger antioxidant capacity during summer than during winter. Also, the experimental UV exposure showed a depletion in antioxidant defences, indicating a negative effect of UV exposure on the total oxyradical scavenging capacity. Another sympagic organism, Onisimus nanseni, was sampled during summer conditions. When compared to G. wilkitzkii, the species showed even higher antioxidant scavenging capacity.

  8. Electrochemical analysis of the UV treated bactericidal Ti6Al4V surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Pacha-Olivenza, Miguel A. [Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN) (Spain); Department of Applied Physics, Faculty of Science, University of Extremadura, Av. Elvas s/n, 06071 Badajoz (Spain); Gallardo-Moreno, Amparo M., E-mail: amparogm@unex.es [Department of Applied Physics, Faculty of Science, University of Extremadura, Av. Elvas s/n, 06071 Badajoz (Spain); Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN) (Spain); Vadillo-Rodríguez, Virginia; González-Martín, M. Luisa [Department of Applied Physics, Faculty of Science, University of Extremadura, Av. Elvas s/n, 06071 Badajoz (Spain); Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN) (Spain); Pérez-Giraldo, Ciro [Department of Microbiology, Faculty of Medicine, University of Extremadura, Av. Elvas s/n, 06071 Badajoz (Spain); Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN) (Spain); Galván, Juan C. [National Centre for Metallurgical Research (CENIM-CSIC), Av. Gregorio del Amo 8, 28040-Madrid (Spain)

    2013-04-01

    This research investigates in detail the bactericidal effect exhibited by the surface of the biomaterial Ti6Al4V after being subjected to UV-C light. It has been recently hypothesized that small surface currents, occurring as a consequence of the electron–hole pair recombination taking place after the excitation process, are behind the bactericidal properties displayed by this UV-treated material. To corroborate this hypothesis we have used different electrochemical techniques, such as electrochemical impedance spectroscopy (EIS), potentiodynamic polarization plots and Mott–Schottky plots. EIS and Mott–Schottky plots have shown that UV-C treatment causes an initial increase on the surface electrical conduction of this material. In addition, EIS and polarization plots demonstrated that higher corrosion currents occur at the UV treated than at the non-irradiated samples. Despite this increase in the corrosion currents, EIS has also shown that such currents are not likely to affect the good stability of this material oxide film since the irradiated samples completely recovered the control values after being stored in dark conditions for a period not longer than 24 h. These results agree with the already-published in vitro transitory behavior of the bactericidal effect, which was shown to be present at initial times after the biomaterial implantation, a crucial moment to avoid a large number of biomaterial associated infections. Highlights: ► Bactericidal response of UV-treated Ti6Al4V is explained through electrochemistry. ► There is an increase in the superficial electrical conduction after UV-treatment. ► Higher corrosion currents for UV-treated against non-UV-treated samples are shown. ► EIS shows the recuperation on irradiated samples in agreement with microbial tests.

  9. Electrochemical analysis of the UV treated bactericidal Ti6Al4V surfaces

    International Nuclear Information System (INIS)

    Pacha-Olivenza, Miguel A.; Gallardo-Moreno, Amparo M.; Vadillo-Rodríguez, Virginia; González-Martín, M. Luisa; Pérez-Giraldo, Ciro; Galván, Juan C.

    2013-01-01

    This research investigates in detail the bactericidal effect exhibited by the surface of the biomaterial Ti6Al4V after being subjected to UV-C light. It has been recently hypothesized that small surface currents, occurring as a consequence of the electron–hole pair recombination taking place after the excitation process, are behind the bactericidal properties displayed by this UV-treated material. To corroborate this hypothesis we have used different electrochemical techniques, such as electrochemical impedance spectroscopy (EIS), potentiodynamic polarization plots and Mott–Schottky plots. EIS and Mott–Schottky plots have shown that UV-C treatment causes an initial increase on the surface electrical conduction of this material. In addition, EIS and polarization plots demonstrated that higher corrosion currents occur at the UV treated than at the non-irradiated samples. Despite this increase in the corrosion currents, EIS has also shown that such currents are not likely to affect the good stability of this material oxide film since the irradiated samples completely recovered the control values after being stored in dark conditions for a period not longer than 24 h. These results agree with the already-published in vitro transitory behavior of the bactericidal effect, which was shown to be present at initial times after the biomaterial implantation, a crucial moment to avoid a large number of biomaterial associated infections. Highlights: ► Bactericidal response of UV-treated Ti6Al4V is explained through electrochemistry. ► There is an increase in the superficial electrical conduction after UV-treatment. ► Higher corrosion currents for UV-treated against non-UV-treated samples are shown. ► EIS shows the recuperation on irradiated samples in agreement with microbial tests

  10. Algorithms and programs for processing of satellite data on ozone layer and UV radiation levels

    International Nuclear Information System (INIS)

    Borkovskij, N.B.; Ivanyukovich, V.A.

    2012-01-01

    Some algorithms and programs for automatic retrieving and processing ozone layer satellite data are discussed. These techniques are used for reliable short-term UV-radiation levels forecasting. (authors)

  11. Hyperspectral Surface Analysis for Ripeness Estimation and Quick UV-C Surface Treatments for Preservation of Bananas

    Science.gov (United States)

    Zhao, W.; Yang, Zh.; Chen, Zh.; Liu, J.; Wang, W. Ch.; Zheng, W. Yu.

    2016-05-01

    This study aimed to determine the ripeness of bananas using hyperspectral surface analysis and how a rapid UV-C (ultraviolet-C light) surface treatment could reduce decay. The surface of the banana fruit and its stages of maturity were studied using a hyperspectral imaging technique in the visible and near infrared (370-1000 nm) regions. The vselected color ratios from these spectral images were used for classifying the whole banana into immature, ripe, half-ripe and overripe stages. By using a BP neural network, models based on the wavelengths were developed to predict quality attributes. The mean discrimination rate was 98.17%. The surface of the fresh bananas was treated with UV-C at dosages from 15-55 μW/cm2. The visual qualities with or without UV-C treatment were compared using the image, the chromatic aberration test, the firmness test and the area of black spot on the banana skin. The results showed that high dosages of UV-C damaged the banana skin, while low dosages were more efficient at delaying changes in the relative brightness of the skin. The maximum UV-C treatment dose for satisfactory banana preservation was between 21 and 24 μW/cm2. These results could help to improve the visual quality of bananas and to classify their ripeness more easily.

  12. Modelling UV irradiances on arbitrarily oriented surfaces: effects of sky obstructions

    Directory of Open Access Journals (Sweden)

    M. Hess

    2008-07-01

    Full Text Available A method is presented to calculate UV irradiances on inclined surfaces that additionally takes into account the influence of sky obstructions caused by obstacles such as mountains, houses, trees, or umbrellas. With this method it is thus possible to calculate the impact of UV radiation on biological systems, such as, for instance, the human skin or eye, in any natural or artificial environment. The method, which consists of a combination of radiation models, is explained here and the accuracy of its results is demonstrated. The effect of a natural skyline is shown for an Alpine ski area, where the UV irradiance even on a horizontal surface may increase due to reflection from snow by more than 10 percent. In contrast, in a street canyon the irradiance on a horizontal surface is reduced to 30% in shadow and to about 75% for a position in the sun.

  13. Modelling UV irradiances on arbitrarily oriented surfaces: effects of sky obstructions

    Science.gov (United States)

    Hess, M.; Koepke, P.

    2008-07-01

    A method is presented to calculate UV irradiances on inclined surfaces that additionally takes into account the influence of sky obstructions caused by obstacles such as mountains, houses, trees, or umbrellas. With this method it is thus possible to calculate the impact of UV radiation on biological systems, such as, for instance, the human skin or eye, in any natural or artificial environment. The method, which consists of a combination of radiation models, is explained here and the accuracy of its results is demonstrated. The effect of a natural skyline is shown for an Alpine ski area, where the UV irradiance even on a horizontal surface may increase due to reflection from snow by more than 10 percent. In contrast, in a street canyon the irradiance on a horizontal surface is reduced to 30% in shadow and to about 75% for a position in the sun.

  14. UV-Surface Treatment of Fungal Resistant Polyether Polyurethane Film-Induced Growth of Entomopathogenic Fungi.

    Science.gov (United States)

    Lando, Gabriela Albara; Marconatto, Letícia; Kessler, Felipe; Lopes, William; Schrank, Augusto; Vainstein, Marilene Henning; Weibel, Daniel Eduardo

    2017-07-18

    Synthetic polymers are the cause of some major environmental impacts due to their low degradation rates. Polyurethanes (PU) are widely used synthetic polymers, and their growing use in industry has produced an increase in plastic waste. A commercial polyether-based thermoplastic PU with hydrolytic stability and fungus resistance was only attacked by an entomopathogenic fungus, Metarhiziumanisopliae , when the films were pre-treated with Ultraviolet (UV) irradiation in the presence of reactive atmospheres. Water contact angle, Fourier transform infrared spectroscopy in attenuated total reflection mode (FTIR-ATR), scanning electron microscopy (SEM), and profilometer measurements were mainly used for analysis. Permanent hydrophilic PU films were produced by the UV-assisted treatments. Pristine polyether PU films incubated for 10, 30, and 60 days did not show any indication of fungal growth. On the contrary, when using oxygen in the UV pre-treatment a layer of fungi spores covered the sample, indicating a great adherence of the microorganisms to the polymer. However, if acrylic acid vapors were used during the UV pre-treatment, a visible attack by the entomopathogenic fungi was observed. SEM and FTIR-ATR data showed clear evidence of fungal development: growth and ramifications of hyphae on the polymer surface with the increase in UV pre-treatment time and fungus incubation time. The results indicated that the simple UV surface activation process has proven to be a promising alternative for polyether PU waste management.

  15. UV-Surface Treatment of Fungal Resistant Polyether Polyurethane Film-Induced Growth of Entomopathogenic Fungi

    Directory of Open Access Journals (Sweden)

    Gabriela Albara Lando

    2017-07-01

    Full Text Available Synthetic polymers are the cause of some major environmental impacts due to their low degradation rates. Polyurethanes (PU are widely used synthetic polymers, and their growing use in industry has produced an increase in plastic waste. A commercial polyether-based thermoplastic PU with hydrolytic stability and fungus resistance was only attacked by an entomopathogenic fungus, Metarhiziumanisopliae, when the films were pre-treated with Ultraviolet (UV irradiation in the presence of reactive atmospheres. Water contact angle, Fourier transform infrared spectroscopy in attenuated total reflection mode (FTIR-ATR, scanning electron microscopy (SEM, and profilometer measurements were mainly used for analysis. Permanent hydrophilic PU films were produced by the UV-assisted treatments. Pristine polyether PU films incubated for 10, 30, and 60 days did not show any indication of fungal growth. On the contrary, when using oxygen in the UV pre-treatment a layer of fungi spores covered the sample, indicating a great adherence of the microorganisms to the polymer. However, if acrylic acid vapors were used during the UV pre-treatment, a visible attack by the entomopathogenic fungi was observed. SEM and FTIR-ATR data showed clear evidence of fungal development: growth and ramifications of hyphae on the polymer surface with the increase in UV pre-treatment time and fungus incubation time. The results indicated that the simple UV surface activation process has proven to be a promising alternative for polyether PU waste management.

  16. Low-level laser irradiation protects the chick embryo chorioallantoic membrane from UV cytotoxicity

    Directory of Open Access Journals (Sweden)

    Hammami Amira

    2018-01-01

    Full Text Available Low-level laser therapy or photobiomodulation is the medical use of a very low intensity light in the red to near infrared (wavelengths in the range of 630-940 nm. The present work was conducted to explore the effects of both UV and low-level laser irradiation (LLLI on microcirculation using the in vivo model of the chick embryo chorioallantoic membrane (CAM. The effects were assessed by measuring lipid peroxidation and antioxidant enzyme activity. Cell cytotoxicity, survival and intracellular reactive oxygen species (ROS of the CAM were also evaluated. We found that UV irradiation induced alterations of the vessels, leading to bleeding and extravasation. This effect was intensified after 60 min of exposure to UV irradiation, leading to marked edema. UVA irradiation increased cell cytotoxicity as assessed by lactate dehydrogenase (LDH release (56.23% of control and reduced cell viability as assessed by decreased fluorescein diacetate (FDA fluorescence (56.23% of control. Pretreatment with LLLI prior to UV exposure protected the CAM tissue from UV-mediated cell death. This protective effect was supported by the observation of significantly inhibited lipid peroxidation (from 0.3±0.004 for UV, to 0.177±0.012 after LLLI pretreatment, ROS and O2 -production, as indicated by respective dihydrorhodamine (DHR and dihydroethidium (DHE intensities (from 132.78% of control for UVA, to 95.90% of control for L-UV (DHR, and from 127.34% of control for UVA, to 82.03% of control for L-UV (DHE, and by preventing the increase in oxidative activities. LLLI efficiently protected CAM cells from UV-induced oxidative stress and appeared as a safe protective pretreatment against UV irradiation.

  17. UV laser-ablated surface textures as potential regulator of cellular response.

    Science.gov (United States)

    Chandra, Prafulla; Lai, Karen; Sung, Hak-Joon; Murthy, N Sanjeeva; Kohn, Joachim

    2010-06-01

    Textured surfaces obtained by UV laser ablation of poly(ethylene terephthalate) films were used to study the effect of shape and spacing of surface features on cellular response. Two distinct patterns, cones and ripples with spacing from 2 to 25 μm, were produced. Surface features with different shapes and spacings were produced by varying pulse repetition rate, laser fluence, and exposure time. The effects of the surface texture parameters, i.e., shape and spacing, on cell attachment, proliferation, and morphology of neonatal human dermal fibroblasts and mouse fibroblasts were studied. Cell attachment was the highest in the regions with cones at ∼4 μm spacing. As feature spacing increased, cell spreading decreased, and the fibroblasts became more circular, indicating a stress-mediated cell shrinkage. This study shows that UV laser ablation is a useful alternative to lithographic techniques to produce surface patterns for controlling cell attachment and growth on biomaterial surfaces.

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

    Science.gov (United States)

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

    2008-09-01

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

  19. Study of UV surface plasmons on metallic nanostructures and its applications to nanophotonics

    Science.gov (United States)

    Zhou, Liangcheng

    Modern nanotechnology requires the characterization ability in the order of 100 nm or smaller. This resolution requirement cannot be met by using conventional optical microscopy. Nowadays, the mainstream technique that is universally adopted to characterize optical properties on this length scale is Near-field Scanning Optical Microscopy (NSOM). In the effort to improve the resolution and efficiency of NSOM techniques, both nanoscopic fabrication and imaging techniques are critical because the light field strongly intereacts with the metallic NSOM probe or other surfaces to form surface plasmons (SPs). However, much is still unknown about the behavior of light interacting with metallic nanostructures. This calls for research that develops the tool set, methodology and that includes both experimental characterization, and numerical simulations, for the investigation of SPs. The short wavelength of UV light makes it particularly desirable for many industrial processes. So far, little research has been carried out to understand surface plasmon in the UV spectral region. Like conventional optics, UV SPs have unique properties and optical behavior. For this purpose, we modified our existing NSOM into a Photon Scanning Tunneling Microscope (PTSM) and demonstrate its power for the imaging of UV SPs. We present what we believe to be the first direct mapping of the UV SPs on an Al2O3/Al surface. UV SP modes launched by one-dimensional slits or two-dimensional groove arrays and corresponding interference phenomenon were both observed. We then use the same methodology in the engineering of optimized nano aperture such as UV bowtie nanoantenna. For the latter, we find a strong UV intensity profile which is localized to less than 50nm caused by a localized surface plasmon resonance. The relationship of optical field enhancement and antenna geometric shape is studied using numerical simulations and NSOM experiments. In another project, we examine the propagation of light from

  20. The influence of surface topography of UV coated and printed cardboard on the print gloss

    Directory of Open Access Journals (Sweden)

    Igor Karlović

    2010-09-01

    Full Text Available The incident light on the printed surface undergoes through several processes of scattering, absorbtion and reflectiondepending on the surface topography and structure of the material. The specular part of the surface reflection is commonlyattributed as the geometric component of the reflection, and when measured is associated with specular gloss.The diffuse part of the surface reflection contains the chromatic part of the reflection and is commonly calculatedthrough colorimetric values. Using UV coatings as surface enhacement materials which affect the optical propertiesof coated surfaces and final appearance of the printed product forms new surface topography over the existingone. We have investigated the influence of three different amounts of UV glossy and matte oveprint coating on themeasured specular gloss of printed cardboard samples. The different amount of coatings on the printed samples wereachived using three different screen stencils of 180 threads/cm, 150 threads/cm and 120 threads/cm thread count.The cardboard samples were analysed with AFM and SEM microscopes to obtain surface topography and roughnessvalues which were evaluated with the measured geometric values speficied as instrumental gloss. The surfaceswith a specific amount of UV coatings showed a new formed topography which influences the reflection of light.The changes in topography were evaluated through surface roughness parameters which showed a decline of surfaceroughness with tht additional ammount of glossy and matte coatings. The obtained and calculated correlations showthere is a high correlation between coating ammount and surface roughness change and gloss for the glossy UVcoating. The results for the matte UV coatings showed lower correlation for the gloss and surface roughness.

  1. Morphology of IR and UV Laser-induced Structural Changes on Silicon Surfaces

    International Nuclear Information System (INIS)

    Jimenez-Jarquin, J.; Haro-Poniatowski, E.; Fernandez-Guasti, M.; Hernandez-Pozos, J.L.

    2005-01-01

    Using scanning electronic microscopy, we analyze the structural changes induced in silicon (100) wafers by focused IR (1064 nm) and UV (355 nm) nanosecond laser pulses. The experiments were performed in the laser ablation regime. When a silicon surface is irradiated by laser pulses in an O2 atmosphere conical microstructures are obtained. The changes in silicon surface morphology depend both on the incident radiation wavelength and the environmental atmosphere. We have patterned Si surfaces with a single focused laser spot and, in doing the experiments with IR or UV this reveals significant differences in the initial surface cracking and pattern formation, however the final result consist of an array of microcones when the experiment is carried out in oxygen. We employ a random scanning technique to irradiate silicon surfaces over large areas. In this form we have obtained large patterned areas

  2. Researchers lack data on trends in UV radiation at Earth's surface

    International Nuclear Information System (INIS)

    Zurer, P.S.

    1993-01-01

    Current anxiety about depletion of stratospheric ozone stems from the expected resulting increase in biologically damaging ultraviolet (UV) radiation at Earth's surface. Atmospheric ozone absorbs sunlight with wavelengths shorter than 320 nm--the highest-energy UV-B wavelengths (280-320 nm) that can damage DNA in living systems. But surprisingly, despite firm evidence the ozone layer is being eroded by chlorine and bromine from man-made compounds, very little information exists on how UV light intensity is changing. Solid data from Antarctica reveal that UV radiation soars under the ozone hole, where fully half of the atmospheric ozone is destroyed each spring. But elsewhere on the globe, where ozone has been thinning at a rate of a few percent per decade, the corresponding trends in UV intensity are not at all clear. In the late 1970s and early 1980s the problem of ozone depletion seemed solved. The US had banned the use of chlorofluorocarbons (CFCs) in aerosols. Model calculations were predicting CFCs would cause only a small loss of ozone by the second half of the 21st century. Costly monitoring of UV radiation commanded little attention. Attitudes began to change with the 1985 discovery of the Antarctic ozone hole. The National Science Foundation (NSF) established UV monitoring stations in the Antarctic in 1988, adding an Alaskan station in 1990. Both the Department of Agriculture (USDA) and the Environmental Protection Agency (EPA) have programs in the works that will eventually place monitoring stations across the US, but it will be many years before researchers have access to the kind of extensive database necessary to reliably evaluation long-term trends in UV intensity

  3. Multispectral UV imaging for surface analysis of MUPS tablets with special focus on the pellet distribution

    DEFF Research Database (Denmark)

    Novikova, Anna; Carstensen, Jens Michael; Rades, Thomas

    2016-01-01

    In the present study the applicability of multispectral UV imaging in combination with multivariate image analysis for surface evaluation of MUPS tablets was investigated with respect to the differentiation of the API pellets from the excipients matrix, estimation of the drug content as well as p...... image analysis is a promising approach for the automatic quality control of MUPS tablets during the manufacturing process....

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

    Czech Academy of Sciences Publication Activity Database

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

    2010-01-01

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

  5. Surface modification of silica nanoparticles by UV-induced graft polymerization of methyl methacrylate.

    Science.gov (United States)

    Kim, Sooyeon; Kim, Eunhye; Kim, Sungsoo; Kim, Woosik

    2005-12-01

    In this study we modified the surface of silica nanoparticles with methyl methacrylate by UV-induced graft polymerization. It is a surface-initiated polymerization reaction induced by ultraviolet irradiation. The resulting organic-inorganic nanocomposites were near-monodisperse and fabricated without homopolymerization of the monomer. Substantial increase in mean particle size was observed by SEM image analysis after UV-induced grafting of methyl methacrylate onto pure silica particles. FT-Raman spectroscopy and X-ray photoelectron spectroscopy studies of these materials revealed the successful grafting of methyl methacrylate onto the silica surface. The formation of a covalent bond between the grafted PMMA chains and silica surface was indicated by FT-Raman spectra. Thermogravimetric analysis of the PMMA-grafted silica particles indicated the polymer contents in good agreement with SEM photographs.

  6. UV and plasma treatment of thin silver layers and glass surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Hluschi, J.H. [University of Applied Sciences and Arts, Von-Ossietzky-Str. 99, D-37085 Goettingen (Germany); Helmke, A. [University of Applied Sciences and Arts, Von-Ossietzky-Str. 99, D-37085 Goettingen (Germany); Roth, P. [University of Applied Sciences and Arts, Von-Ossietzky-Str. 99, D-37085 Goettingen (Germany); Boewer, R. [Interpane Glasbeschichtungsgesellschaft mbH and Co KG, Sohnreystr. 21, D-37697 Lauenfoerde (Germany); Herlitze, L. [Interpane Glasbeschichtungsgesellschaft mbH and Co KG, Sohnreystr. 21, D-37697 Lauenfoerde (Germany); Vioel, W. [University of Applied Sciences and Arts, Von-Ossietzky-Str. 99, D-37085 Goettingen (Germany)]. E-mail: vioel@hawk-hhg.de

    2006-11-10

    Thin silver layers can be modified by treatment with UV radiation or a plasma discharge. UV treatment at a wavelength of {lambda}=308 -bar nm improves the layer properties, thus leading to an enhancement of the layers IR reflectivity. For the purpose of in situ-measurement the sheet resistance is recorded during the process. Due to the Hagen-Rubens-Relation [E. Hagen, H. Rubens, Ann. Phys. 11 (1903) 873]-bar the sheet resistance is linked to the IR reflectivity of thin metal-films. A pretreatment of uncoated glass using a dielectric barrier discharge activates and cleans its surface, thus leading to an increase in adhesion of thin layers.

  7. Chemical imaging and solid state analysis at compact surfaces using UV imaging

    DEFF Research Database (Denmark)

    Wu, Jian X.; Rehder, Sönke; van den Berg, Frans

    2014-01-01

    and excipients in a non-invasive way, as well as mapping the glibenclamide solid state form. An exploratory data analysis supported the critical evaluation of the mapping results and the selection of model parameters for the chemical mapping. The present study demonstrated that the multi-wavelength UV imaging......Fast non-destructive multi-wavelength UV imaging together with multivariate image analysis was utilized to visualize distribution of chemical components and their solid state form at compact surfaces. Amorphous and crystalline solid forms of the antidiabetic compound glibenclamide...

  8. UV and plasma treatment of thin silver layers and glass surfaces

    International Nuclear Information System (INIS)

    Hluschi, J.H.; Helmke, A.; Roth, P.; Boewer, R.; Herlitze, L.; Vioel, W.

    2006-01-01

    Thin silver layers can be modified by treatment with UV radiation or a plasma discharge. UV treatment at a wavelength of λ=308 -bar nm improves the layer properties, thus leading to an enhancement of the layers IR reflectivity. For the purpose of in situ-measurement the sheet resistance is recorded during the process. Due to the Hagen-Rubens-Relation [E. Hagen, H. Rubens, Ann. Phys. 11 (1903) 873]-bar the sheet resistance is linked to the IR reflectivity of thin metal-films. A pretreatment of uncoated glass using a dielectric barrier discharge activates and cleans its surface, thus leading to an increase in adhesion of thin layers

  9. An assessment of ozone levels, UV radiation and their occupational health hazard estimation during photocopying operation

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Bhupendra Pratap, E-mail: bpsingh0783@gmail.com; Kumar, Amit; Singh, Deepak; Punia, Monika; Kumar, Krishan; Jain, Vinod Kumar

    2014-06-30

    Highlights: • First quantitative report of ozone level and UV radiation emission from photocopier. • Ozone production is directly proportional with intensity of photocopy operation. • Ozone level from ground floor is significantly higher than basement photocopier. • Ozone production and UV radiation studied has less correlation during photocopy. • Health hazard issue has been evaluated for effect of UV radiation in terms of SED. - Abstract: This study investigates the levels of ozone concentration along with an ultraviolet (UV) and visible spectral radiation at eight photocopy centers in an academic institute, Delhi. Sampling was done in two types of locations, i.e., basement photocopy centers (BPC) and ground floor photocopy centers (GPC) for 8 h. Measurements of levels of ozone, UV and visible radiation were done by ozone analyzer, UV radiometer and Field spectra instrument, respectively. Results show that the hourly mean concentration of ozone was observed to be in the range of 1.8–10.0 ppb and 5.3–45.8 ppb for BPC and GPC, respectively. In terms UV radiations, energy lies between 5.0 × 10{sup −3} and 7.0 × 10{sup −3} mW/cm{sup 2} for ultraviolet A (UVA), 1.0 × 10{sup −3} and 2.0 × 10{sup −3} mW/cm{sup 2} for ultraviolet B (UVB) and 6.0 × 10{sup −3} and 8.0 × 10{sup −3} mW/cm{sup 2} for ultraviolet C (UVC). Correlation between the UV radiations and ozone production observed was statistically insignificant. To know the health hazard occurred to the workers, the standard erythema dose (SED) value was calculated for emitting UV radiation. The SED was estimated to be in the range of 0.02–0.04 and 0.02–0.32 for direct and indirect methods which is less than the guideline prescribed by Commission Internationale del’ Eclairage (CIE). In nutshell, person involved in photocopy operation for their livelihood must be trained and should have knowledge for the long term gradual build up health problems due to ozone and UV production from

  10. IR and UV laser-induced morphological changes in silicon surface under oxygen atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez-Jarquin, J.; Fernandez-Guasti, M.; Haro-Poniatowski, E.; Hernandez-Pozos, J.L. [Laboratorio de Optica Cuantica, Departamento de Fisica, Universidad Autonoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco No. 186, Col. Vicentina, C.P. 09340, Mexico D.F. (Mexico)

    2005-08-01

    We irradiated silicon (100) wafers with IR (1064 nm) and UV (355 nm) nanosecond laser pulses with energy densities within the ablation regime and used scanning electron microscopy to analyze the morphological changes induced on the Si surface. The changes in the wafer morphology depend both on the incident radiation wavelength and the environmental atmosphere. We have patterned Si surfaces with a single focused laser spot and, in doing the experiments with IR or UV this reveals significant differences in the initial surface cracking and pattern formation, however if the experiment is carried out in O{sub 2} the final result is an array of microcones. We also employed a random scanning technique to irradiate the silicon wafer over large areas, in this case the microstructure patterns consist of a ''semi-ordered'' array of micron-sized cones. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Reconstruction of solar spectral surface UV irradiances using radiative transfer simulations.

    Science.gov (United States)

    Lindfors, Anders; Heikkilä, Anu; Kaurola, Jussi; Koskela, Tapani; Lakkala, Kaisa

    2009-01-01

    UV radiation exerts several effects concerning life on Earth, and spectral information on the prevailing UV radiation conditions is needed in order to study each of these effects. In this paper, we present a method for reconstruction of solar spectral UV irradiances at the Earth's surface. The method, which is a further development of an earlier published method for reconstruction of erythemally weighted UV, relies on radiative transfer simulations, and takes as input (1) the effective cloud optical depth as inferred from pyranometer measurements of global radiation (300-3000 nm); (2) the total ozone column; (3) the surface albedo as estimated from measurements of snow depth; (4) the total water vapor column; and (5) the altitude of the location. Reconstructed daily cumulative spectral irradiances at Jokioinen and Sodankylä in Finland are, in general, in good agreement with measurements. The mean percentage difference, for instance, is mostly within +/-8%, and the root mean square of the percentage difference is around 10% or below for wavelengths over 310 nm and daily minimum solar zenith angles (SZA) less than 70 degrees . In this study, we used pseudospherical radiative transfer simulations, which were shown to improve the performance of our method under large SZA (low Sun).

  12. Validation of an HPLC–UV method for the determination of digoxin residues on the surface of manufacturing equipment

    Directory of Open Access Journals (Sweden)

    ZORAN B. TODOROVIĆ

    2009-09-01

    Full Text Available In the pharmaceutical industry, an important step consists in the removal of possible drug residues from the involved equipments and areas. The cleaning procedures must be validated and methods to determine trace amounts of drugs have, therefore, to be considered with special attention. An HPLC–UV method for the determination of digoxin residues on stainless steel surfaces was developed and validated in order to control a cleaning procedure. Cotton swabs, moistened with methanol were used to remove any residues of drugs from stainless steel surfaces, and give recoveries of 85.9, 85.2 and 78.7 % for three concentration levels. The precision of the results, reported as the relative standard deviation (RSD, were below 6.3 %. The method was validated over a concentration range of 0.05–12.5 µg mL-1. Low quantities of drug residues were determined by HPLC–UV using a Symmetry C18 column (150´4.6 mm, 5 µm at 20 °C with an acetonitrile–water (28:72, v/v mobile phase at a flow rate of 1.1 mL min-1, an injection volume of 100 µL and were detected at 220 nm. A simple, selective and sensitive HPLC–UV assay for the determination of digoxin residues on stainless steel was developed, validated and applied.

  13. Development and Testing of the New Surface LER Climatology for OMI UV Aerosol Retrievals

    Science.gov (United States)

    Gupta, Pawan; Torres, Omar; Jethva, Hiren; Ahn, Changwoo

    2014-01-01

    Ozone Monitoring Instrument (OMI) onboard Aura satellite retrieved aerosols properties using UV part of solar spectrum. The OMI near UV aerosol algorithm (OMAERUV) is a global inversion scheme which retrieves aerosol properties both over ocean and land. The current version of the algorithm makes use of TOMS derived Lambertian Equivalent Reflectance (LER) climatology. A new monthly climatology of surface LER at 354 and 388 nm have been developed. This will replace TOMS LER (380 nm and 354nm) climatology in OMI near UV aerosol retrieval algorithm. The main objectives of this study is to produce high resolution (quarter degree) surface LER sets as compared to existing one degree TOMS surface LERs, to product instrument and wavelength consistent surface climatology. Nine years of OMI observations have been used to derive monthly climatology of surface LER. MODIS derived aerosol optical depth (AOD) have been used to make aerosol corrections on OMI wavelengths. MODIS derived BRDF adjusted reflectance product has been also used to capture seasonal changes in the surface characteristics. Finally spatial and temporal averaging techniques have been used to fill the gaps around the globes, especially in the regions with consistent cloud cover such as Amazon. After implementation of new surface data in the research version of algorithm, comparisons of AOD and single scattering albedo (SSA) have been performed over global AERONET sites for year 2007. Preliminary results shows improvements in AOD retrievals globally but more significance improvement were observed over desert and bright locations. We will present methodology of deriving surface data sets and will discuss the observed changes in retrieved aerosol properties with respect to reference AERONET measurements.

  14. Biodosimetric analysis of medium pressure UV disinfection reactor treating unfiltered surface water

    International Nuclear Information System (INIS)

    Leinan, B.E.; Craik, S.A.; Smith, D.W.; Belosevic, M.

    2002-01-01

    Many small and medium-sized communities use chlorination of surface water as their sole treatment of potable water. Ultraviolet (UV) disinfection may offer these communities a cost effective treatment option for protection against pathogens not readily inactivated by chlorine. The effectiveness of UV reactors for microorganism reduction, however, is sensitive to UV dose delivery, which is in turn influenced by water quality characteristics. The effectiveness of a Calgon Carbon Inc. Sentinel medium-pressure UV reactor for microorganism reduction was determined using biodosimetry with two non-pathogenic indicator organisms - MS2 phage and Bacillus subtilis. Testing was conducted using low turbidity (<0.5 NTU) lake water characterized by relatively high absorbance in the UV range (UVT of approx. 87 to 88% at 254 nm). The efficiency of UV dose delivery in the reactor was determined for various operating conditions by calculating the normalized reductive equivalent irradiance (REI). With a single lamp in operation, the normalized REI measured with B. subtilis increased significantly when the flow rate through the reactor was increased from 380 L/min to 1140 L/min. This increase in reactor efficiency was believed to be due to improved reactor hydrodynamics and axial mixing that accompanied the higher flow rates. In contrast, treatment efficiency based on biodosimetry with MS2 phage was found to decrease with increasing flow rate when a single lamp was in operation. In general, treatment efficiency was greater when more than one adjacent lamp was in operation, suggesting that the influence of flow short-circuiting with single lamp operation. Differences between the outcomes observed with the two indicator microorganisms were not resolved, however, it was concluded that reactor efficiency was sensitive to both water flow rate and the number of adjacent lamps that were in operation. (author)

  15. Operational surface UV radiation product from GOME-2 and AVHRR/3 data

    OpenAIRE

    J. Kujanpää; N. Kalakoski

    2015-01-01

    The surface ultraviolet (UV) radiation product, version 1.20, generated operationally in the framework of the Satellite Application Facility on Ozone and Atmospheric Chemistry Monitoring (O3M SAF) of the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) is described. The product is based on the total ozone column derived from the measurements of the second Global Ozone Monitoring Experiment (GOME-2) instrument aboard EUMETSA...

  16. Response surface methodology as a tool for modeling and optimization of Bacillus subtilis spores inactivation by UV/ nano-Fe0 process for safe water production.

    Science.gov (United States)

    Yousefzadeh, Samira; Matin, Atiyeh Rajabi; Ahmadi, Ehsan; Sabeti, Zahra; Alimohammadi, Mahmood; Aslani, Hassan; Nabizadeh, Ramin

    2018-04-01

    One of the most important aspects of environmental issues is the demand for clean and safe water. Meanwhile, disinfection process is one of the most important steps in safe water production. The present study aims at estimating the performance of UV, nano Zero-Valent Iron particles (nZVI, nano-Fe 0 ), and UV treatment with the addition of nZVI (combined process) for Bacillus subtilis spores inactivation. Effects of different factors on inactivation including contact time, initial nZVI concentration, UV irradiance and various aerations conditions were investigated. Response surface methodology, based on a five-level, two variable central composite design, was used to optimize target microorganism reduction and the experimental parameters. The results indicated that the disinfection time had the greatest positive impact on disinfection ability among the different selected independent variables. According to the results, it can be concluded that microbial reduction by UV alone was more effective than nZVI while the combined UV/nZVI process demonstrated the maximum log reduction. The optimum reduction of about 4 logs was observed at 491 mg/L of nZVI and 60 min of contact time when spores were exposed to UV radiation under deaerated condition. Therefore, UV/nZVI process can be suggested as a reliable method for Bacillus subtilis spores inactivation. Copyright © 2018. Published by Elsevier Ltd.

  17. A Facile in Situ and UV Printing Process for Bioinspired Self-Cleaning Surfaces

    Directory of Open Access Journals (Sweden)

    Marina A. González Lazo

    2016-08-01

    Full Text Available A facile in situ and UV printing process was demonstrated to create self-cleaning synthetic replica of natural petals and leaves. The process relied on the spontaneous migration of a fluorinated acrylate surfactant (PFUA within a low-shrinkage acrylated hyperbranched polymer (HBP and its chemical immobilization at the polymer-air interface. Dilute concentrations of 1 wt. % PFUA saturated the polymer-air interface within 30 min, leading to a ten-fold increase of fluorine concentration at the surface compared with the initial bulk concentration and a water contact angle (WCA of 108°. A 200 ms flash of UV light was used to chemically crosslink the PFUA at the HBP surface prior to UV printing with a polydimethylsiloxane (PDMS negative template of red and yellow rose petals and lotus leaves. This flash immobilization hindered the reverse migration of PFUA within the bulk HBP upon contacting the PDMS template, and enabled to produce texturized surfaces with WCA well above 108°. The synthetic red rose petal was hydrophobic (WCA of 125° and exhibited the adhesive petal effect. It was not superhydrophobic due to insufficient concentration of fluorine at its surface, a result of the very large increase of the surface of the printed texture. The synthetic yellow rose petal was quasi-superhydrophobic (WCA of 143°, roll-off angle of 10° and its self-cleaning ability was not good also due to lack of fluorine. The synthetic lotus leaf did not accurately replicate the intricate nanotubular crystal structures of the plant. In spite of this, the fluorine concentration at the surface was high enough and the leaf was superhydrophobic (WCA of 151°, roll-off angle below 5° and also featured self-cleaning properties.

  18. A novel method to prepare superhydrophobic, UV resistance and anti-corrosion steel surface

    KAUST Repository

    Isimjan, Tayirjan T.

    2012-11-01

    Both TiO 2 and SiO 2 coated steel surfaces containing micro- and nanoscale binary structures with different surface roughness were successfully fabricated by means of a facile layer by layer deposition process followed by heat treatment. The resulting surfaces were modified by the low free energy chemical PTES (1H,1H,2H,2H-Perfluorodecyltriethoxysilane). The experimental results of wettability exhibit that such modified surfaces have a strong repulsive force to water droplets, their static contact angles exceed 165°, receding angle>160°, advanced angles>170° and slide angle<1°. The resulting surfaces not only exhibit superhydrophobic properties but also show strong UV resistance (after coating SiO 2 on top of TiO 2) and strong stability to various solvents including 0.01% HCl solution. © 2012 Elsevier B.V.

  19. Radiation Level Changes at RAM Package Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Opperman, Erich [Washington Savannah River Company; Hawk, Mark B [ORNL; Kapoor, Ashok [U.S. Department of Energy, Office of Packaging and Transportation; Natali, Ronald [R. B. Natali Consulting, Inc.

    2010-01-01

    This paper will explore design considerations required to meet the regulations that limit radiation level variations at external surfaces of radioactive material (RAM) packages. The radiation level requirements at package surfaces (e.g. TS-R-1 paragraphs 531 and 646) invoke not only maximum radiation levels, but also strict limits on the allowable increase in the radiation level during transport. This paper will explore the regulatory requirements by quantifying the amount of near surface movement and/or payload shifting that results in a 20% increase in the radiation level at the package surface. Typical IP-2, IP-3, Type A and Type B packaging and source geometries will be illustrated. Variations in surface radiation levels are typically the result of changes in the geometry of the surface due to an impact, puncture or crush event, or shifting and settling of radioactive contents.

  20. Dermal damage promoted by repeated low-level UV-A1 exposure despite tanning response in human skin.

    Science.gov (United States)

    Wang, Frank; Smith, Noah R; Tran, Bao Anh Patrick; Kang, Sewon; Voorhees, John J; Fisher, Gary J

    2014-04-01

    Solar UV irradiation causes photoaging, characterized by fragmentation and reduced production of type I collagen fibrils that provide strength to skin. Exposure to UV-B irradiation (280-320 nm) causes these changes by inducing matrix metalloproteinase 1 and suppressing type I collagen synthesis. The role of UV-A irradiation (320-400 nm) in promoting similar molecular alterations is less clear yet important to consider because it is 10 to 100 times more abundant in natural sunlight than UV-B irradiation and penetrates deeper into the dermis than UV-B irradiation. Most (approximately 75%) of solar UV-A irradiation is composed of UV-A1 irradiation (340-400 nm), which is also the primary component of tanning beds. To evaluate the effects of low levels of UV-A1 irradiation, as might be encountered in daily life, on expression of matrix metalloproteinase 1 and type I procollagen (the precursor of type I collagen). In vivo biochemical analyses were conducted after UV-A1 irradiation of normal human skin at an academic referral center. Participants included 22 healthy individuals without skin disease. Skin pigmentation was measured by a color meter (chromometer) under the L* variable (luminescence), which ranges from 0 (black) to 100 (white). Gene expression in skin samples was assessed by real-time polymerase chain reaction. Lightly pigmented human skin (L* >65) was exposed up to 4 times (1 exposure/d) to UV-A1 irradiation at a low dose (20 J/cm2), mimicking UV-A levels from strong sun exposure lasting approximately 2 hours. A single exposure to low-dose UV-A1 irradiation darkened skin slightly and did not alter matrix metalloproteinase 1 or type I procollagen gene expression. With repeated low-dose UV-A1 irradiation, skin darkened incrementally with each exposure. Despite this darkening, 2 or more exposures to low-dose UV-A1 irradiation significantly induced matrix metalloproteinase 1 gene expression, which increased progressively with successive exposures. Repeated UV-A1

  1. Responses to Projected Changes in Climate and UV-B at the Species Level

    Energy Technology Data Exchange (ETDEWEB)

    Callaghan, Terry V. [Abisko Scientific Research Station, Abisko (Sweden); Bjoern, Lars Olof [Lund Univ. (Sweden). Dept. of Cell and Organism Biology; Cernov, Yuri [Russian Academy of Sciences, Moscow (Russian Federation). A.N. Severtsov Inst. of Evolutionary Morphology and Animal Ecology] (and others)

    2004-11-01

    Environmental manipulation experiments showed that species respond individualistically to each environmental-change variable. The greatest responses of plants were generally to nutrient, particularly nitrogen, addition. Summer warming experiments showed that woody plant responses were dominant and that mosses and lichens became less abundant. Responses to warming were controlled by moisture availability and snow cover. Many invertebrates increased population growth in response to summer warming, as long as desiccation was not induced. CO{sub 2} and UV-B enrichment experiments showed that plant and animal responses were small. However, some microorganisms and species of fungi were sensitive to increased UV-B and some intensive mutagenic actions could, perhaps, lead to unexpected epidemic outbreaks. Tundra soil heating, CO{sub 2} enrichment and amendment with mineral nutrients generally accelerated microbial activity. Algae are likely to dominate cyanobacteria in milder climates. Expected increases in winter freeze-thaw cycles leading to ice-crust formation are likely to severely reduce winter survival rate and disrupt the population dynamics of many terrestrial animals. A deeper snow cover is likely to restrict access to winter pastures by reindeer/caribou and their ability to flee from predators while any earlier onset of the snow-free period is likely to stimulate increased plant growth. Initial species responses to climate change might occur at the sub-species level: an Arctic plant or animal species with high genetic/racial diversity has proved an ability to adapt to different environmental conditions in the past and is likely to do so also in the future. Indigenous knowledge, air photographs, satellite images and monitoring show that changes in the distributions of some species are already occurring: Arctic vegetation is becoming more shrubby and more productive, there have been recent changes in the ranges of caribou, and 'new' species of insects and

  2. First Derivative UV Spectra of Surface Water as a Monitor of Chlorination in Drinking Water Treatment

    Directory of Open Access Journals (Sweden)

    V. Zitko

    2001-01-01

    Full Text Available Many countries require the presence of free chlorine at about 0.1 mg/l in their drinking water supplies. For various reasons, such as cast-iron pipes or long residence times in the distribution system, free chlorine may decrease below detection limits. In such cases it is important to know whether or not the water was chlorinated or if nonchlorinated water entered the system by accident. Changes in UV spectra of natural organic matter in lakewater were used to assess qualitatively the degree of chlorination in the treatment to produce drinking water. The changes were more obvious in the first derivative spectra. In lakewater, the derivative spectra have a maximum at about 280 nm. This maximum shifts to longer wavelengths by up to 10 nm, decreases, and eventually disappears with an increasing dose of chlorine. The water treatment system was monitored by this technique for over 1 year and changes in the UV spectra of water samples were compared with experimental samples treated with known amounts of chlorine. The changes of the UV spectra with the concentration of added chlorine are presented. On several occasions, water, which received very little or no chlorination, may have entered the drinking water system. The results show that first derivative spectra are potentially a tool to determine, in the absence of residual chlorine, whether or not surface water was chlorinated during the treatment to produce potable water.

  3. Comparative researches concerning cleaning chosen construction materials surface layer using UV and IR laser radiation

    International Nuclear Information System (INIS)

    Napadlek, W.; Marczak, J.; Kubicki, J.; Szudrowicz, M.

    2002-01-01

    The paper presents comparative research studies of cleaning out of deposits and pollution disposals on different constructional materials like; steel, cast iron, aluminium, copper by using UV and IR laser radiation of wavelength λ =1.064 μm; λ = 0.532 μm; λ = 0.355 μm and λ = 0.266 μm and also impulse laser TEA CO 2 at radiation λ = 10.6 μm were used for the experiments. Achieved experimental results gave us basic information on parameters and conditions and application of each used radiation wavelength. Each kind of pollution and base material should be individually treated, selecting the length of wave and radiation energy density. Laser microtreatment allows for broad cleaning application of the surface of constructional materials as well as may be used in future during manufacturing processes as: preparation of surface for PVD technology, galvanotechnics, cleaning of the surface of machine parts etc. (author)

  4. Damage caused by a nanosecond UV laser on a heated copper surface

    Energy Technology Data Exchange (ETDEWEB)

    Henč-Bartolić, V., E-mail: visnja.henc@fer.hr [University of Zagreb, Faculty of Electrical Engineering and Computing, Unska 3, 10000 Zagreb (Croatia); Bončina, T. [University of Maribor, Faculty of Mechanical Engineering, Smetanova 17, 2000 Maribor (Slovenia); Jakovljević, S., E-mail: suzana.jakovljevic@fsb.hr [University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture, Ivana Lučića 5, 10002 Zagreb (Croatia); Panjan, P. [Jožef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia); Zupanič, F. [University of Maribor, Faculty of Mechanical Engineering, Smetanova 17, 2000 Maribor (Slovenia)

    2016-08-15

    Highlights: • A Cu-plate was exposed to nanosecond UV laser with max. energy 1.1 J/cm{sup 2}. • Surface topography was studied on the cold and heated copper plate. • At room temperature, a crater formed, the melt was ejected from it. • Capillary waves formed in the vicinity of the crater at 360 °C. - Abstract: This work studied the effect of thin copper plate temperature on its surface morphology after irradiation using a pulsed nanosecond UV laser. The surface characteristics were investigated using scanning electron microscopy, energy dispersive X-ray spectroscopy, focused ion beam and stylus profilometry. When a target was at room temperature, a crater and the radial flow of molten Cu from the crater was observed. When the thin target was warm (about 360 °C ± 20 °C), a crater was smaller, and quasi-semicircular waves with the periodicity of around 3 μm appeared in its vicinity. The origin of the waves is Marangoni effect, causing thermocapillary waves, which in same occasions had a structure of final states of chaos in Rayleigh–Bénard convection.

  5. Increased levels of unscheduled DNA synthesis in UV-irradiated human fibroblasts pretreated with sodium butyrate

    International Nuclear Information System (INIS)

    Williams, J.I.; Friedberg, E.C.

    1982-01-01

    Pretreatment of growing normal and xeroderma pigmentosum (XP) human fibroblasts with sodium butyrate at concentrations of 5-20 mM results in increased levels of DNA repair synthesis measured by autoradiography after exposure of the cells to 254 nm UV radiation in the fluence range 0-25 J/m 2 . The phenomenon manifests as an increased extent and an increased initial rate of unscheduled DNA synthesis (UDS). This experimental result is not due to an artifact of autoradiography related to cell size. Xeroderma pigmentosum cells from complementation groups A, C, D and E and XP variant cells all exhibit increases in the levels of UV-induced UDS in response to sodium butyrate proportional to those observed with normal cells. These UDS increases associated with butyrate pretreatment correlate with demonstrable changes in intracellular thymidine pool size and suggest that sodium butyrate enhances uptake of exogenous radiolabeled thymidine during UV-induced repair synthesis by reducing endogenous levels of thymidine. (author)

  6. A portable UV-fluorescence multispectral imaging system for the analysis of painted surfaces

    Science.gov (United States)

    Comelli, Daniela; Valentini, Gianluca; Nevin, Austin; Farina, Andrea; Toniolo, Lucia; Cubeddu, Rinaldo

    2008-08-01

    A portable fluorescence multispectral imaging system was developed and has been used for the analysis of artistic surfaces. The imaging apparatus exploits two UV lamps for fluorescence excitation and a liquid crystal tunable filter coupled to a low-noise charge coupled device as the image detector. The main features of the system are critically presented, outlining the assets, drawbacks, and practical considerations of portability. A multivariate statistical treatment of spectral data is further considered. Finally, the in situ analysis with the new apparatus of recently restored Renaissance wall paintings is presented.

  7. Different levels of UV-B resistance in Vaccinium corymbosum cultivars reveal distinct backgrounds of phenylpropanoid metabolites.

    Science.gov (United States)

    Luengo Escobar, Ana; Magnum de Oliveira Silva, Franklin; Acevedo, Patricio; Nunes-Nesi, Adriano; Alberdi, Miren; Reyes-Díaz, Marjorie

    2017-09-01

    UV-B radiation induces several physiological and biochemical effects that can influence regulatory plant processes. Vaccinium corymbosum responds differently to UV-B radiation depending on the UV-B resistance of cultivars, according to their physiological and biochemical features. In this work, the effect of two levels of UV-B radiation during long-term exposure on the phenylpropanoid biosynthesis, and the expression of genes associated with flavonoid biosynthesis as well as the absolute quantification of secondary metabolites were studied in two contrasting UV-B-resistant cultivars (Legacy, resistant and Bluegold, sensitive). Multivariate analyses were performed to understand the role of phenylpropanoids in UV-B defense mechanisms. The amount of phenylpropanoid compounds was generally higher in Legacy than in Bluegold. Different expression levels of flavonoid biosynthetic genes for both cultivars were transiently induced, showing that even in longer period of UV-B exposure; plants are still adjusting their phenylpropanoids at the transcription levels. Multivariate analysis in Legacy indicated no significant correlation between gene expression and the levels of the flavonoids and phenolic acids. By contrast, in the Bluegold cultivar higher number of correlations between secondary metabolite and transcript levels was found. Taken together, the results indicated different adjustments between the cultivars for a successful UV-B acclimation. While the sensitive cultivar depends on metabolite adjustments to respond to UV-B exposure, the resistant cultivar also possesses an intrinsically higher antioxidant and UV-B screening capacity. Thus, we conclude that UV-B resistance involves not only metabolite level adjustments during the acclimation period, but also depends on the intrinsic metabolic status of the plant and metabolic features of the phenylpropanoid compounds. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  8. Increased cell surface metallopeptidase activity in cells undergoing UV-induced apoptosis

    International Nuclear Information System (INIS)

    Piva, T.J.; Davern, C.M.; Ellem, K.A.O.

    1999-01-01

    Full text: We have previously shown that UVC irradiation activated a range of cell surface peptidases (CSP) in HeLa cell monolayer cultures 20 h post-irradiation (1). In cells undergoing apoptosis there is an increase in CSP activity compared to control viable cells in cultures which have been treated by a wide range of agents including UV-irradiation (2). In order to further understand the mechanism involved in this process, we induced apoptosis in HeLa cells using 500 Jm -2 UVB. The separation of viable, apoptotic and necrotic cells of irradiated HeLa cell cultures was made by FACS analysis and sorting. The three populations were distinguished by their staining with PI and Hoechst 33342 dyes. CSP activity was measured using the P9 assay developed in this laboratory (1-3). The viable fraction of the irradiated cells had a higher level of CSP activity compared to unirradiated controls. The level of CSP activity in the apoptotic fraction was higher than that of the viable fraction, however that of the necrotic fraction was significantly lower. This finding agreed with that seen in UVC-irradiated (50 Jm -2 ) cultures (2). In order to elucidate the mechanism by which CSP activity was increased in UVB-irradiated cells undergoing apoptosis, the cultures were treated with the following agents: bestatin, aminopeptidase inhibitor, DEVD, caspase 3 inhibitor, and 3-aminobenzamide (3AB), PARP activation inhibitor. Bestatin and DEVD did not affect the level of CSP activity in the different cell subpopulations following UVB-irradiation. Treatment with 3AB abolished the increased CSP activity seen in the viable and apoptotic fraction following UVB-irradiation. All treated cells had the same morphology as observed under EM. The degree of phosphatidylserine eversion on the cell membrane was similar as were the cleavage profiles of PARP and actin. Only DEVD-treated cells had reduced caspase 3 activity which confirmed that the activation of CSP activity in apoptotic cells is

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-09-15

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

  10. Formation of quasi-periodic nano- and microstructures on silicon surface under IR and UV femtosecond laser pulses

    International Nuclear Information System (INIS)

    Ionin, Andrei A; Golosov, E V; Kolobov, Yu R; Kudryashov, Sergei I; Ligachev, A E; Makarov, Sergei V; Novoselov, Yurii N; Seleznev, L V; Sinitsyn, D V

    2011-01-01

    Quasi-periodic nano- and microstructures have been formed on silicon surface using IR ( λ ≈ 744 nm) and UV ( λ ≈ 248 nm) femtosecond laser pulses. The influence of the incident energy density and the number of pulses on the structured surface topology has been investigated. The silicon nanostructurisation thresholds have been determined for the above-mentioned wavelengths. Modulation of the surface relief at the doubled spatial frequency is revealed and explained qualitatively. The periods of the nanostructures formed on the silicon surface under IR and UV femtosecond laser pulses are comparatively analysed and discussed.

  11. Thermal and UV Hydrosilylation of Alcohol-Based Bifunctional Alkynes on Si (111) surfaces: How surface radicals influence surface bond formation.

    Science.gov (United States)

    Khung, Y L; Ngalim, S H; Scaccabarozi, A; Narducci, D

    2015-06-12

    Using two different hydrosilylation methods, low temperature thermal and UV initiation, silicon (111) hydrogenated surfaces were functionalized in presence of an OH-terminated alkyne, a CF3-terminated alkyne and a mixed equimolar ratio of the two alkynes. XPS studies revealed that in the absence of premeditated surface radical through low temperature hydrosilylation, the surface grafting proceeded to form a Si-O-C linkage via nucleophilic reaction through the OH group of the alkyne. This led to a small increase in surface roughness as well as an increase in hydrophobicity and this effect was attributed to the surficial etching of silicon to form nanosize pores (~1-3 nm) by residual water/oxygen as a result of changes to surface polarity from the grafting. Furthermore in the radical-free thermal environment, a mix in equimolar of these two short alkynes can achieve a high contact angle of ~102°, comparable to long alkyl chains grafting reported in literature although surface roughness was relatively mild (rms = ~1 nm). On the other hand, UV initiation on silicon totally reversed the chemical linkages to predominantly Si-C without further compromising the surface roughness, highlighting the importance of surface radicals determining the reactivity of the silicon surface to the selected alkynes.

  12. Surface Chloride Levels in Colorado Structural Concrete

    Science.gov (United States)

    2018-01-01

    This project focused on the chloride-induced corrosion of reinforcing steel in structural concrete. The primary goal of this project is to analyze the surface chloride concentration level of the concrete bridge decks throughout Colorado. The study in...

  13. Surface modification induced by UV nanosecond Nd:YVO4 laser structuring on biometals

    Science.gov (United States)

    Fiorucci, M. Paula; López, Ana J.; Ramil, Alberto

    2014-08-01

    Laser surface texturing is a promising tool for improving metallic biomaterials performance in dental and orthopedic bone-replacing applications. Laser ablation modifies the topography of bulk material and might alter surface properties that govern the interactions with the surrounding tissue. This paper presents a preliminary evaluation of surface modifications in two biometals, stainless steel 316L and titanium alloy Ti6Al4V by UV nanosecond Nd:YVO4. Scanning electron microscopy of the surface textured by parallel micro-grooves reveals a thin layer of remelted material along the grooves topography. Furthermore, X-ray diffraction allowed us to appreciate a grain refinement of original crystal structure and consequently induced residual strain. Changes in the surface chemistry were determined by means of X-ray photoelectron spectroscopy; in this sense, generalized surface oxidation was observed and characterization of the oxides and other compounds such hydroxyl groups was reported. In case of titanium alloy, oxide layer mainly composed by TiO2 which is a highly biocompatible compound was identified. Furthermore, laser treatment produces an increase in oxide thickness that could improve the corrosion behavior of the metal. Otherwise, laser treatment led to the formation of secondary phases which might be detrimental to physical and biocompatibility properties of the material.

  14. Barium fluoride surface preparation, analysis and UV reflective coatings at Lawrence Livermore National Laboratory

    International Nuclear Information System (INIS)

    Wuest, C.R.

    1992-01-01

    Lawrence Livermore National Laboratory (LLNL) has begun a program of study on barium fluoride scintillating crystals for the Barium Fluoride Electromagnetic Calorimeter Collaboration. This program has resulted in a number of significant improvements in the mechanical processing, polishing and coating of barium fluoride crystals. Techniques have been developed using diamond-loaded pitch lapping that can produce 15 angstrom RMS surface finishes over large areas. These lapped surfaces have been shown to be crystalline using Rutherford Back-scattering (RBS). Also, special polishing fixtures have been designed based on mounting technology developed for the 1.1 m diameter optics used in LLNL's Nova Laser. These fixtures allow as many as five 25--50 cm long barium fluoride crystals to be polished and lapped at a time with the necessary tolerances for the 16,000 crystal Barium Fluoride Calorimeter. In addition, results will be presented on coating barium fluoride with UV reflective layers of magnesium fluoride and aluminum

  15. UV laser ablation of intraocular lenses: SEM and AFM microscopy examination of the biomaterial surface

    International Nuclear Information System (INIS)

    Spyratou, E.; Asproudis, I.; Tsoutsi, D.; Bacharis, C.; Moutsouris, K.; Makropoulou, M.; Serafetinides, A.A.

    2010-01-01

    Several new materials and patterns are studied for the formation and etching of intraocular lenses (IOLs), in order to improve their optical properties, to reduce the diffractive aberrations and to decrease the incidence of posterior capsular opacification. The aim of this study is to investigate the use of UV (λ = 266 nm) laser pulses to ablate the intraocular lenses materials, and thus to provide an alternative to conventional surface shaping techniques for IOLs fabrication. Ablation experiments were conducted using various polymer substrates of hydrophobic acrylic IOLs and PMMA IOLs. We investigated the ablation efficiency and the morphology of the ablated area by imaging the surface modification with atomic force microscopy (AFM) and scanning electron microscopy (SEM). The morphological appearance of IOL samples reveals the effect of a photochemical and photothermal ablation mechanism.

  16. Selective cell culture on UV transparent polymer by F2 laser surface modification

    International Nuclear Information System (INIS)

    Hanada, Yasutaka; Sugioka, Koji; Kawano, Hiroyuki; Tsuchimoto, Takayoshi; Miyamoto, Iwao; Miyawaki, Atsushi; Midorikawa, Katsumi

    2009-01-01

    A microchip made of UV transparent polymer (CYTOP) that can perform selective cell culture has been fabricated by F 2 laser surface modification. The refractive index of CYTOP is almost the same as that of culture medium, which is essential for three-dimensional (3D) observation of cells. The F 2 laser modification of CYTOP achieves hydrophilicity only on the laser irradiated area with little deterioration of the optical properties and surface smoothness. After the laser modification, HeLa cells were successfully cultured and strongly adhered only on the modified area of CYTOP. The cells patterned on CYTOP were applied for clear 3D observation using an optical microscope in phase contrast mode.

  17. UV laser ablation of intraocular lenses: SEM and AFM microscopy examination of the biomaterial surface

    Energy Technology Data Exchange (ETDEWEB)

    Spyratou, E., E-mail: ellas5@central.ntua.gr [National Technical University of Athens, School of Applied Mathematical and Physical Sciences, Department of Physics, Zografou Campus, Athens, 15780 (Greece); Asproudis, I. [Department of Ophthalmology, University Hospital of Ioannina, Ioannina, 45110 (Greece); Tsoutsi, D. [Department of Chemistry, University of Ioannina, Ioannina, 45110 (Greece); Bacharis, C.; Moutsouris, K.; Makropoulou, M.; Serafetinides, A.A. [National Technical University of Athens, School of Applied Mathematical and Physical Sciences, Department of Physics, Zografou Campus, Athens, 15780 (Greece)

    2010-02-01

    Several new materials and patterns are studied for the formation and etching of intraocular lenses (IOLs), in order to improve their optical properties, to reduce the diffractive aberrations and to decrease the incidence of posterior capsular opacification. The aim of this study is to investigate the use of UV ({lambda} = 266 nm) laser pulses to ablate the intraocular lenses materials, and thus to provide an alternative to conventional surface shaping techniques for IOLs fabrication. Ablation experiments were conducted using various polymer substrates of hydrophobic acrylic IOLs and PMMA IOLs. We investigated the ablation efficiency and the morphology of the ablated area by imaging the surface modification with atomic force microscopy (AFM) and scanning electron microscopy (SEM). The morphological appearance of IOL samples reveals the effect of a photochemical and photothermal ablation mechanism.

  18. Structural origin of surface transformations in arsenic sulfide thin films upon UV-irradiation

    International Nuclear Information System (INIS)

    Kovalskiy, Andriy; Vlcek, Miroslav; Palka, Karel; Buzek, Jan; York-Winegar, James; Oelgoetz, Justin; Golovchak, Roman; Shpotyuk, Oleh; Jain, Himanshu

    2017-01-01

    Photostructural transformations within As_xS_1_0_0_-_x (x = 30, 33, 35, 40) thin films upon exposure to LED light of different wavelengths, in both air and argon environments have been studied by high resolution XPS, Raman spectroscopy and LEIS methods. These complementary results show that light of energies close to the band gap does not modify chemical composition of the surface, but induces simple photopolymerization reactions. Superbandgap UV light, however, significantly increases S/As ratio on the surface due to formation of S-rich layer under both environmental conditions. It is proposed that photovaporization of both oxide and non-oxide cage-like molecules is responsible for the observed effect.

  19. Structural origin of surface transformations in arsenic sulfide thin films upon UV-irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Kovalskiy, Andriy, E-mail: kovalskiya@apsu.edu [Department of Physics & Astronomy, Austin Peay State University, 601 College St., Clarksville, TN 37044 (United States); Vlcek, Miroslav [Center of Materials and Nanotechnologies, Faculty of Chemical Technology, University of Pardubice, nam. Cs. Legii 565, 530 02 Pardubice (Czech Republic); Palka, Karel [Center of Materials and Nanotechnologies, Faculty of Chemical Technology, University of Pardubice, nam. Cs. Legii 565, 530 02 Pardubice (Czech Republic); Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentska 573, 532 10 Pardubice (Czech Republic); Buzek, Jan [Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentska 573, 532 10 Pardubice (Czech Republic); York-Winegar, James; Oelgoetz, Justin; Golovchak, Roman [Department of Physics & Astronomy, Austin Peay State University, 601 College St., Clarksville, TN 37044 (United States); Shpotyuk, Oleh [Vlokh Institute of Physical Optics, 23 Dragomanov str., Lviv 79005 (Ukraine); Institute of Physics of Jan Dlugosz University, 13/15 al. Armii Krajowej, Czestochowa PL-42201 (Poland); Jain, Himanshu [Department of Materials Science & Engineering, Lehigh University, 5 East Packer Ave., Bethlehem, PA 18015 (United States)

    2017-02-01

    Photostructural transformations within As{sub x}S{sub 100-x} (x = 30, 33, 35, 40) thin films upon exposure to LED light of different wavelengths, in both air and argon environments have been studied by high resolution XPS, Raman spectroscopy and LEIS methods. These complementary results show that light of energies close to the band gap does not modify chemical composition of the surface, but induces simple photopolymerization reactions. Superbandgap UV light, however, significantly increases S/As ratio on the surface due to formation of S-rich layer under both environmental conditions. It is proposed that photovaporization of both oxide and non-oxide cage-like molecules is responsible for the observed effect.

  20. Far-UV photochemical bond cleavage of n-amyl nitrite: bypassing a repulsive surface.

    Science.gov (United States)

    Minitti, Michael P; Zhang, Yao; Rosenberg, Martin; Brogaard, Rasmus Y; Deb, Sanghamitra; Sølling, Theis I; Weber, Peter M

    2012-01-19

    We have investigated the deep-UV photoinduced, homolytic bond cleavage of amyl nitrite to form NO and pentoxy radicals. One-color multiphoton ionization with ultrashort laser pulses through the S(2) state resonance gives rise to photoelectron spectra that reflect ionization from the S(1) state. Time-resolved pump-probe photoionization measurements show that upon excitation at 207 nm, the generation of NO in the v = 2 state is delayed, with a rise time of 283 (16) fs. The time-resolved mass spectrum shows the NO to be expelled with a kinetic energy of 1.0 eV, which is consistent with dissociation on the S(1) state potential energy surface. Combined, these observations show that the first step of the dissociation reaction involves an internal conversion from the S(2) to the S(1) state, which is followed by the ejection of the NO radical on the predissociative S(1) state potential energy surface.

  1. Selective cell culture on UV transparent polymer by F{sub 2} laser surface modification

    Energy Technology Data Exchange (ETDEWEB)

    Hanada, Yasutaka, E-mail: y-hanada@riken.jp [RIKEN-Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Sugioka, Koji [RIKEN-Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Kawano, Hiroyuki [RIKEN-Brain Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Tsuchimoto, Takayoshi [RIKEN-Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Department of Applied Electronics, Faculty of Industrial Science and Technology Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510 (Japan); Miyamoto, Iwao [Department of Applied Electronics, Faculty of Industrial Science and Technology Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510 (Japan); Miyawaki, Atsushi [RIKEN-Brain Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Midorikawa, Katsumi [RIKEN-Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)

    2009-09-30

    A microchip made of UV transparent polymer (CYTOP) that can perform selective cell culture has been fabricated by F{sub 2} laser surface modification. The refractive index of CYTOP is almost the same as that of culture medium, which is essential for three-dimensional (3D) observation of cells. The F{sub 2} laser modification of CYTOP achieves hydrophilicity only on the laser irradiated area with little deterioration of the optical properties and surface smoothness. After the laser modification, HeLa cells were successfully cultured and strongly adhered only on the modified area of CYTOP. The cells patterned on CYTOP were applied for clear 3D observation using an optical microscope in phase contrast mode.

  2. MEASUREMENT OF SURFACE SOLAR UV-B RADIATION AT TROPICAL COASTAL STATION BAKKHALI IN WEST BENGAL, INDIA

    OpenAIRE

    R. BHATTACHARYA; A. BHOUMICK

    2012-01-01

    Surface solar ultraviolet irradiance has been measured at Bakkhali (21.8ºN, 87.8ºE), a tropical rural station on the coast of Bay of Bengal, India in West Bengal. The measurements show a remarkable variation in UV-B load exists with a peak value at noon. The blockage of direct UV radiation in mangrove forest of costal site appears low when compared with UV load beneath the multiple trees of Mangifera indica in an inland site of Kalyani (22058' N, 88028' E), West Bengal. Mangrove forests have ...

  3. Ultraviolet (UV)-reflective paint with ultraviolet germicidal irradiation (UVGI) improves decontamination of nosocomial bacteria on hospital room surfaces.

    Science.gov (United States)

    Jelden, Katelyn C; Gibbs, Shawn G; Smith, Philip W; Hewlett, Angela L; Iwen, Peter C; Schmid, Kendra K; Lowe, John J

    2017-06-01

    An ultraviolet germicidal irradiation (UVGI) generator (the TORCH, ClorDiSys Solutions, Inc.) was used to compare the disinfection of surface coupons (plastic from a bedrail, stainless steel, and chrome-plated light switch cover) in a hospital room with walls coated with ultraviolet (UV)-reflective paint (Lumacept) or standard paint. Each surface coupon was inoculated with methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant Enterococcus faecalis (VRE), placed at 6 different sites within a hospital room coated with UV-reflective paint or standard paint, and treated by 10 min UVC exposure (UVC dose of 0-688 mJ/cm 2 between sites with standard paint and 0-553 mJ/cm 2 with UV-reflective paint) in 8 total trials. Aggregated MRSA concentrations on plastic bedrail surface coupons were reduced on average by 3.0 log 10 (1.8 log 10 Geometric Standard Deviation [GSD]) with standard paint and 4.3 log 10 (1.3 log 10 GSD) with UV-reflective paint (p = 0.0005) with no significant reduction differences between paints on stainless steel and chrome. Average VRE concentrations were reduced by ≥4.9 log 10 (surface types with UV-reflective paint and ≤4.1 log 10 (hospital bed from the UVGI generator, MRSA concentrations on average were reduced by 1.3 log 10 (1.7 log 10 GSD) with standard paint and 4.7 log 10 (1.3 log 10 GSD) with UV-reflective paint (p hospital room walls with UV-reflective paint enhanced UVGI disinfection of nosocomial bacteria on various surfaces compared to standard paint, particularly at a surface placement site indirectly exposed to UVC light.

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

    Directory of Open Access Journals (Sweden)

    R. A. Danilov

    2000-12-01

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

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

    International Nuclear Information System (INIS)

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

    2009-01-01

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

  6. Slide-free histology via MUSE: UV surface excitation microscopy for imaging unsectioned tissue (Conference Presentation)

    Science.gov (United States)

    Levenson, Richard M.; Harmany, Zachary; Demos, Stavros G.; Fereidouni, Farzad

    2016-03-01

    Widely used methods for preparing and viewing tissue specimens at microscopic resolution have not changed for over a century. They provide high-quality images but can involve time-frames of hours or even weeks, depending on logistics. There is increasing interest in slide-free methods for rapid tissue analysis that can both decrease turn-around times and reduce costs. One new approach is MUSE (microscopy with UV surface excitation), which exploits the shallow penetration of UV light to excite fluorescent signals from only the most superficial tissue elements. The method is non-destructive, and eliminates requirement for conventional histology processing, formalin fixation, paraffin embedding, or thin sectioning. It requires no lasers, confocal, multiphoton or optical coherence tomography optics. MUSE generates diagnostic-quality histological images that can be rendered to resemble conventional hematoxylin- and eosin-stained samples, with enhanced topographical information, from fresh or fixed, but unsectioned tissue, rapidly, with high resolution, simply and inexpensively. We anticipate that there could be widespread adoption in research facilities, hospital-based and stand-alone clinical settings, in local or regional pathology labs, as well as in low-resource environments.

  7. Periodic nanostructures fabricated on GaAs surface by UV pulsed laser interference

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wei; Huo, Dayun; Guo, Xiaoxiang; Rong, Chen; Shi, Zhenwu, E-mail: zwshi@suda.edu.cn; Peng, Changsi, E-mail: changsipeng@suda.edu.cn

    2016-01-01

    Graphical abstract: - Highlights: • Periodic nanostructures were fabricated on GaAs wafers by four-beam laser interference patterning which have potential applications in many fields. • Significant different results were obtained on epi-ready and homo-epitaxial GaAs substrate surfaces. • Two-pulse patterning was carried out on homo-epitaxial GaAs substrate, a noticeable morphology transformation induced by the second pulse was observed. • Temperature distribution on sample surface as a function of time and position was calculated by solving the heat diffusion equations. The calculation agrees well with the experiment results. - Abstract: In this paper, periodic nanostructures were fabricated on GaAs wafers by four-beam UV pulsed laser interference patterning. Significant different results were observed on epi-ready and homo-epitaxial GaAs substrate surfaces, which suggests GaAs oxide layer has an important effect on pulsed laser irradiation process. In the case of two-pulse patterning, a noticeable morphology transformation induced by the second pulse was observed on homo-epitaxial GaAs substrate. Based on photo-thermal mode, temperature distribution on sample surface as a function of time and position was calculated by solving the heat diffusion equations.

  8. DNA repair pathways involved in determining the level of cytotoxicity of environmentally relevant UV radiation

    International Nuclear Information System (INIS)

    Carpenter, L.

    2000-01-01

    The sensitivity of cell lines with defects in various DNA repair processes to different wavelengths of UV has been assessed in order to determine the importance of these repair pathways to the cytotoxicity of UV light. The cell lines used in this work were xrs-6 (a Chinese Hamster Ovary (CHO) cell line) mutant for XRCC5/Ku80, EM9 a CHO cell line mutant for XRCC1, UV61 a CHO cell line mutant for ERCC6/CSB, and E3p53-/-, a mouse embryonic fibroblast cell line null for p53. Xrs-6 (defective in Non Homologous End-Joining) was found to be sensitive to the cytotoxic effects of broadband UVA, but not narrowband UVA or narrowband UVB. EM9 (defective in Base Excision Repair/Single-Strand Break Repair) was not sensitive to the cytotoxic effects of both broadband and narrowband UVA, narrowband UVB or narrowband UVC. UV61 (defective in the Transcription Coupled Repair branch of Nucleotide Excision Repair) was sensitive to the cytotoxic effects of narrowband UVA, UVB and UVC. E3p53-/- was sensitive to the cytotoxic effects of narrowband UVA and UVB. Broadband UVA was found to induce high levels of chromosomal damage in xrs-6, as quantified by the micronucleus assay, most likely as a result of this cell lines inability to repair DNA double strand breaks. EM9 was found to be defective in the repair of broadband UVA-induced single strand breaks, as measured by the alkaline gel electrophoresis ('comet') assay. UV61 was unable to repair broadband UVB-induced DNA damage as measured by the alkaline gel electrophoresis ('comet') assay. These results provide evidence that: 1. DNA double-strand breaks contribute to the cytotoxicity of UVA to a greater extent than single-strand breaks. 2. Repair mechanisms that operate in response to UVA may be coupled to transcription. 3. UVB may directly induce SSBs. 4. P53 is involved in the response of the cell to both UVA and UVB radiation. (author)

  9. Bioactivating Silicon (100 Surfaces with Novel UV Grafting of Cyclopropylamine for Promotion of Cell Adhesion

    Directory of Open Access Journals (Sweden)

    Jing Yuan Ching

    2018-05-01

    Full Text Available In this report, utraviolent (UV photoionization of cyclopropylamine on silicon (100 hydride was employed to examine interfacing with three different epithelial cell types (MDA-MB 231, AGS and HEC1A. The cellular viability using this novel methodology had been quantified to evaluate the bioactivating potential of this ring-opening chemistry when compared to standardized controls (aminopropyltriethoxylamine, collagen and poly-L lysine. X-ray photospectroscopy (XPS and atomic force microscopy (AFM were used to characterize surface chemistry composition, while cell viability and confocal microscopy after 24 h of incubation were performed. Based on the results acquired from this novel ring-opening metastasis process, the promotion of cell adhesion and viability was found to be higher using this chemistry when compared to other conventional control groups, even for the collagen coating, without any observable issues of cytotoxicity.

  10. Effects of UV-B radiation and water stress on gas exchange of soybeans under two different nitrogen levels

    International Nuclear Information System (INIS)

    Rosa, L.M.; Forseth, I.N.

    1993-01-01

    Due to anthropogenic destruction of stratospheric ozone, UV-B radiation is projected to increase in the near future. Other potential global climate changes in temperature and precipitation patterns raise the need for research into plant responses to multiple environmental stresses. The objective of this study was to document UV-B and water stress effects on gas exchange of soybean (Glycine max Merr.) under two nitrogen levels. Two soybean cultivars differing in sensitivity to UV-B were tested at fluence rates of 19.1 or 8.5 kJ m -2 day -1 (enhance and natural levels of UV-B, respectively). Measurements of photosaturated CO 2 uptake at ambient CO 2 (A). stomatal conductance. photosaturated O 2 evolution at saturating CO 2 (A max ), long term water use efficiency (using δ 13 C), and nitrogen fixation (using 15 N) were performed. No significant treatment effects on A could be detected. However A max was significantly increased, and stomatal conductance reduced (p<0.01) by increased UV-B at all levels of water and nitrogen for both cultivars, suggesting a stronger stomal limitation of photosynthesis under UV-B. Water and nitrogen use efficiency also decreased under increased UV-B in both cultivars (p<0.01)

  11. A case study of the impact of boundary layer aerosol size distribution on the surface UV irradiance

    Energy Technology Data Exchange (ETDEWEB)

    Kikas, U.; Reinhart, A. [University of Tartu (Estonia). Institute of Environmental Physics; Vaht, M. [Parnu Institute of Health Resort Treatment and Medical Rehabilitation (Estonia); Veismann, U. [Tartu Observatory (Estonia)

    2001-07-01

    The relationship between scattering characteristics of surface aerosol and surface UV irradiance was examined on the basis of the measurements carried out in June-August 1999 in Parnu, Estonia on the Eastern coast of the Baltic Sea (58{sup o}22'27 ''N, 24{sup o}30'43 ''E) The UV radiation spectra (300-34Onm) were measured with the Ocean Optics Inc. UV spectrometer PC 1000, the aerosol size distributions (3-1000nm) were measured with the electric aerosol spectrometer EAS. A case study was conducted for six sequential cloudless days, when the decrease of the surface UV irradiance was seemingly influenced by atmospheric aerosol. Aerosol radiative properties were calculated from the measured size distributions that represented the maritime polar (North Atlantic) and mixed maritime-continental air. The aerosol optical depths at 500nm for the North Atlantic air were estimated to be from 0.08 to 0. 13. The spectral aerosol optical depth agreed well with the Angstrom law, the Angstrom exponent ({alpha} varied from day to day between values of 0.52-0.90. Aerosol asymmetry factor at 300nm changed between values of 0.76 and 0.80, and was highly correlated with the mean radius of aerosol number distribution. The total aerosol UV scattering was mostly influenced by changes in aerosol with a diameter of 100-560nm. The aerosol scattering coefficients were positively correlated with the relative humidity of air. The ground aerosol properties were used for calculating the surface UV irradiance from the radiative transfer model of Bird and Riordan (J. Climate Appl. Meteorol. 25 (1986)). The calculated UV irradiances correlated quite well with the measured ones, showing that the use of ground aerosol data for radiative transfer calculations turned out reasonable results. However, ignoring the changes in the aerosol vertical distribution resulted in overestimation of aerosol optical depth on hazy days. (author)

  12. Low levels of iron enhance UV/H2O2 efficiency at neutral pH.

    Science.gov (United States)

    Ulliman, Sydney L; McKay, Garrett; Rosario-Ortiz, Fernando L; Linden, Karl G

    2018-03-01

    While the presence of iron is generally not seen as favorable for UV-based treatment systems due to lamp fouling and decreased UV transmittance, we show that low levels of iron can lead to improvements in the abatement of chemicals in the UV-hydrogen peroxide advanced oxidation process. The oxidation potential of an iron-assisted UV/H 2 O 2 (UV 254  + H 2 O 2  + iron) process was evaluated at neutral pH using iron levels below USEPA secondary drinking water standards (UV/H 2 O 2 systems. The effects of iron species (Fe 2+ and Fe 3+ ), iron concentration (0-0.3 mg/L), H 2 O 2 concentration (0-10 mg/L) and background water matrix (low-carbon tap (LCT) and well water) on HO production and compound removal were examined. Iron-assisted UV/H 2 O 2 efficiency was most influenced by the target chemical and the water matrix. Added iron to UV/H 2 O 2 was shown to increase the steady-state HO concentration by approximately 25% in all well water scenarios. While CBZ removal was unchanged by iron addition, 0.3 mg/L iron improved NDMA removal rates in both LCT and well water matrices by 15.1% and 4.6% respectively. Furthermore, the combination of UV/Fe without H 2 O 2 was also shown to enhance NDMA removal when compared to UV photolysis alone indicating the presence of degradation pathways other than HO oxidation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Effect of enhanced UV-B radiation of adaxial leaf surface micromorphology and epicuticular wax biosynthesis of sugar maple

    International Nuclear Information System (INIS)

    Gordon, D.C.; Percy, K.E.; Riding, R.T.

    1998-01-01

    Sugar maple (Acer saccharum [Marsh.]) seedlings were exposed to UV-B BE ranging from 0.61 kJ m -2 d -1 to 12.48 kJ m -2 d -1 . Increasing UV-B intensity was associated with changes in micromorphological characteristics of the adaxial leaf surface. In vivo incorporation of [1- 14 C] acetate into sugar maple adaxial leaf surface epicuticular wax indicated (p<0.05) a UV-B sensitivity threshold at or near 6.2 kJ m -2 d -1 . Exposure to dosages greater than 6.2 kJ m -2 d -1 resulted in a significant (p<0.05) decrease in wax biosynthesis. The proportion of [1- 14 C] acetate incorporated into each of the different epicuticular wax classes changed with increasing UV-B. Incorporation of [1- 14 C] acetate into alkyl esters decreased while incorporation into alkanes increased with increasing UV-B dose. The effects of enhanced UV-B dose recorded in this experiment may have implications for cuticle function. (author)

  14. Interaction betwen Lead and Bone Protein to Affect Bone Calcium Level Using UV-Vis Spectroscopy

    Science.gov (United States)

    Noor, Z.; Azharuddin, A.; Aflanie, I.; Kania, N.; Suhartono, E.

    2018-05-01

    This present study aim to evaluate the interactions between lead (Pb) and with bone protein by UV-Vis approach. In addition, this prsent study also aim to investigate the effect of Pb on bone calcium (Ca) level. The present study was a true experimental study design to examine the impact of Pb exposure in bone of male rats (Rattus novergicus). The study involved 5 groups, P1 was the control group, while the other (P2-P5) were the case group with exposure of Pb in different concentration within 4 weeks. At the end of the exposure, the interaction between Pb and protein was determined using UV-Vis spectrophotometric method, and the Ca level was determined using permanganometric method. The results shows that that there is an interaction between Pb and bone protein. The result also shows that the value of the binding constant of Protein-Pb is 32.71. It means Pb have an high affinity to bind with bone protein, which promote a further reaction to induced the release of bone Ca from the bone protein. In conclusion, this present study found an obvious relationship between Pb and bone protein which promote a further reaction to increase the releasing of bone calcium.

  15. Photonic crystal structures on nonflat surfaces fabricated by dry lift-off soft UV nanoimprint lithography

    International Nuclear Information System (INIS)

    Sun, Tangyou; Xu, Zhimou; Xu, Haifeng; Zhao, Wenning; Wu, Xinghui; Liu, Sisi; Ma, Zhichao; He, Jian; Liu, Shiyuan; Peng, Jing

    2013-01-01

    The surface nonflatness induced from the material itself or the production atmosphere can lead to serious non-uniformity consequences in nanoimprint lithography (NIL) which is used for providing a low cost and high throughput nano-fabrication process. In this paper, soft UV NIL (SUNIL) processes are used for photonic crystal (PC) pattern transfer of a GaN-based light-emitting diode (LED) with patterned sapphire substrate (PSS). The results reveal a significant incompatibility between the conventional SUNIL and the nonflat p-GaN surface. Ellipse-shaped rather than circle-shaped PC structure is obtained on the p-GaN surface due the deformation of the soft mold in nonflat NIL. A dry lift-off (DLO) SUNIL is proposed to overcome the non-uniformity issue in nonflat NIL as well as the collapse problem of the free-standing pillar-shaped resist in wet lift-off. The photoluminescence enhancements of the LED fabricated by the DLO SUNIL method compared to those with conventional SUNIL and unpatterned LED are 1.41 fold and 3.48 fold, respectively. Further study shows that the DLO SUNIL is applicable in the fabrication of the PC structure with tunable duty cycle via one single initial PC mold. (paper)

  16. Level crossing analysis of growing surfaces

    International Nuclear Information System (INIS)

    Shahbazi, F; Sobhanian, S; Tabar, M Reza Rahimi; Khorram, S; Frootan, G R; Zahed, H

    2003-01-01

    We investigate the average frequency of positive slope ν + α , crossing the height α = h - h-bar in the surface growing processes. The exact level crossing analysis of the random deposition model and the Kardar-Parisi-Zhang equation in the strong coupling limit before creation of singularities is given

  17. Superhydrophilic poly (styrene co acrylonitrile)-ZnO nanocomposite surfaces for UV shielding and self-cleaning applications

    Science.gov (United States)

    Singh, Rajender; Sharma, Ramesh; Barman, P. B.; Sharma, Dheeraj

    2017-11-01

    UV shielding based super hydrophilic material is developed in the present formulation by in situ emulsion polymerization of poly (styrene-acrylonitrile) with ZnO nanoparticles. The ESI-MS technique confirms the structure of polymer nanocomposite by their mass fragments. The XRD study confirms the presence of ZnO phase in polymer matrix. PSAN/ZnO nanocomposite leads to give effective UV shielding (upto 375 nm) and visible luminescence with ZnO content in polymer matrix. The FESEM and TEM studies confirm the symmetrical, controlled growth of PNs. The incorporation of ZnO nanofillers into PSAN matrix lead to restructuring the PNs surfaces into superhydrophilic surfaces in water contact angle (WCA) from 70° to 10°. We believe our synthesized PSAN/ZnO nanocomposite could be potential as UV shielding, luminescent and super hydrophilic nature based materials in related commercial applications.

  18. Surface-to-surface registration using level sets

    DEFF Research Database (Denmark)

    Hansen, Mads Fogtmann; Erbou, Søren G.; Vester-Christensen, Martin

    2007-01-01

    This paper presents a general approach for surface-to-surface registration (S2SR) with the Euclidean metric using signed distance maps. In addition, the method is symmetric such that the registration of a shape A to a shape B is identical to the registration of the shape B to the shape A. The S2SR...... problem can be approximated by the image registration (IR) problem of the signed distance maps (SDMs) of the surfaces confined to some narrow band. By shrinking the narrow bands around the zero level sets the solution to the IR problem converges towards the S2SR problem. It is our hypothesis...... that this approach is more robust and less prone to fall into local minima than ordinary surface-to-surface registration. The IR problem is solved using the inverse compositional algorithm. In this paper, a set of 40 pelvic bones of Duroc pigs are registered to each other w.r.t. the Euclidean transformation...

  19. Influence of cloud fraction and snow cover to the variation of surface UV radiation at King Sejong station, Antarctica

    Science.gov (United States)

    Lee, Yun Gon; Koo, Ja-Ho; Kim, Jhoon

    2015-10-01

    This study investigated how cloud fraction and snow cover affect the variation of surface ultraviolet (UV) radiation by using surface Erythemal UV (EUV) and Near UV (NUV) observed at the King Sejong Station, Antarctica. First the Radiative Amplification Factor (RAF), the relative change of surface EUV according to the total-column ozone amount, is compared for different cloud fractions and solar zenith angles (SZAs). Generally, all cloudy conditions show that the increase of RAF as SZA becomes larger, showing the larger effects of vertical columnar ozone. For given SZA cases, the EUV transmission through mean cloud layer gradually decreases as cloud fraction increases, but sometimes the maximum of surface EUV appears under partly cloudy conditions. The high surface EUV transmittance under broken cloud conditions seems due to the re-radiation of scattered EUV by cloud particles. NUV transmission through mean cloud layer also decreases as cloud amount increases but the sensitivity to the cloud fraction is larger than EUV. Both EUV and NUV radiations at the surface are also enhanced by the snow cover, and their enhancement becomes higher as SZA increases implying the diurnal variation of surface albedo. This effect of snow cover seems large under the overcast sky because of the stronger interaction between snow surface and cloudy sky.

  20. Superhydrophobic TiO2-polymer nanocomposite surface with UV-induced reversible wettability and self-cleaning properties.

    Science.gov (United States)

    Xu, Qian Feng; Liu, Yang; Lin, Fang-Ju; Mondal, Bikash; Lyons, Alan M

    2013-09-25

    Multifunctional superhydrophobic nanocomposite surfaces based on photocatalytic materials, such as fluorosilane modified TiO2, have generated significant research interest. However, there are two challenges to forming such multifunctional surfaces with stable superhydrophobic properties: the photocatalytic oxidation of the hydrophobic functional groups, which leads to the permanent loss of superhydrophobicity, as well as the photoinduced reversible hydrolysis of the catalytic particle surface. Herein, we report a simple and inexpensive template lamination method to fabricate multifunctional TiO2-high-density polyethylene (HDPE) nanocomposite surfaces exhibiting superhydrophobicity, UV-induced reversible wettability, and self-cleaning properties. The laminated surface possesses a hierarchical roughness spanning the micro- to nanoscale range. This was achieved by using a wire mesh template to emboss the HDPE surface creating an array of polymeric posts while partially embedding untreated TiO2 nanoparticles selectively into the top surface of these features. The surface exhibits excellent superhydrophobic properties immediately after lamination without any chemical surface modification to the TiO2 nanoparticles. Exposure to UV light causes the surface to become hydrophilic. This change in wettability can be reversed by heating the surface to restore superhydrophobicity. The effect of TiO2 nanoparticle surface coverage and chemical composition on the mechanism and magnitude of wettability changes was studied by EDX and XPS. In addition, the ability of the surface to shed impacting water droplets as well as the ability of such droplets to clean away particulate contaminants was demonstrated.

  1. Direct UV/Optical Imaging of Stellar Surfaces: The Stellar Imager (SI) Vision Mission

    Science.gov (United States)

    Carpenter, Kenneth G.; Lyon, Richard G.; Schrijver, Carolus; Karovska, Margarita; Mozurkewich, David

    2007-01-01

    The Stellar Imager (SI) is a UV/optical, space-based interferometer designed to enable 0.1 milli-arcsecond (mas) spectral imaging of stellar surfaces and, via asteroseismology, stellar interiors and of the Universe in general. SI's science focuses on the role of magnetism in the Universe, particularly on magnetic activity on the surfaces of stars like the Sun. SI's prime goal is to enable long-term forecasting of solar activity and the space weather that it drives, in support of the Living with a Star program in the Exploration Era. SI will also revolutionize our understanding of the formation of planetary systems, of the habitability and climatology of distant planets, and of many magneto-hydrodynamically controlled processes in thc Universe. SI is a "Flagship and Landmark Discovery Mission" in the 2005 Sun Solar System Connection (SSSC) Roadmap and a candidate for a "Pathways to Life Observatory" in the Exploration of the Universe Division (EUD) Roadmap. We discuss herein the science goals of the SI Mission, a mission architecture that could meet those goals, and the technologies needed to enable this mission. Additional information on SI can be found at: http://hires.gsfc.nasa.gov/si/.

  2. Effect of surface plasmon resonance on the photocatalytic activity of Au/TiO2 under UV/visible illumination.

    Science.gov (United States)

    Tseng, Yao-Hsuan; Chang, I-Guo; Tai, Yian; Wu, Kung-Wei

    2012-01-01

    In this study, gold-loaded titanium dioxide was prepared by an impregnation method to investigate the effect of surface plasmon resonance (SPR) on photoactivity. The deposited gold nanoparticles (NPs) absorb visible light because of SPR. The effects of both the gold content and the TiO2 size of Au/TiO2 on SPR and the photocatalytic efficiency were investigated. The morphology, crystal structure, light absorption, emission from the recombination of a photoexcited electron and hole, and the degree of aggregation were investigated using transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-visible-diffuse reflectance spectra (UV-VIS-DRS), photoluminescence (PL) spectroscopy, and turbidimetry, respectively. Photocatalytic activity was evaluated by the decolorization of methyl orange solution over modified titania under UV and UV/GLED (green light emitting diode) illumination. Au/TiO2 NPs exhibited an absorption peak (530-570 nm) because of SPR. The results of our photocatalytic experiments indicated that the UV-inducedly photocatalytic reaction rate was improved by simultaneously using UV and green light illumination; this corresponds to the adsorption region of SPR. Au/TiO2 could use the enhanced electric field amplitude on the surface of the Au particle in the spectral vicinity of its plasmon resonance and thus improve the photoactivity. Experimental results show that the synergistic effect between UV and green light for the improvement of photoactivity increases with increasing the SPR absorption, which in turn is affected by the Au content and TiO2 size.

  3. Decommissioning high-level waste surface facilities

    International Nuclear Information System (INIS)

    1978-04-01

    The protective storage, entombment and dismantlement options of decommissioning a High-Level Waste Surface Facility (HLWSF) was investigated. A reference conceptual design for the facility was developed based on the designs of similar facilities. State-of-the-art decommissioning technologies were identified. Program plans and cost estimates for decommissioning the reference conceptual designs were developed. Good engineering design concepts were on the basis of this work identified

  4. A simple UV-ozone surface treatment to enhance photocatalytic performance of TiO 2 loaded polymer nanofiber membranes

    KAUST Repository

    Dilpazir, S.

    2016-01-29

    Homogeneously dispersed titanium dioxide loaded polyacrylonitrile nanofiber membranes with increased active mass loading, Ti3+ surface defects and hydrophilicity were fabricated by combining electrospinning and UV-ozone surface treatment. The photocatalytic activity improved by a factor of ∼2 and the kinetics of photodegradation switched from pseudo-first order to pseudo-second order with increasing TiO2 content with a maximum rate constant of 20.7 h-1. © The Royal Society of Chemistry 2016.

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

    International Nuclear Information System (INIS)

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

    1998-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-05-01

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

  7. Surface plasmon resonance spectroscopic study of UV-addressable phenylalanine sensing based on a self-assembled spirooxazine derivative monolayer

    International Nuclear Information System (INIS)

    Suk, Shinae; Suh, Hee-Jung; Gun An, Won; Kim, Jae-Ho; Jin, Sung-Ho; Kim, Sung-Hoon; Gal, Yeong-Soon; Koh, Kwangnak

    2004-01-01

    Light-addressable compounds are very interesting due to the possibilities of their practical use such as optical switches and memories or variable transmission materials. For example, transportation of phenylalanine across liposomal bilayers mediated by a photoresponsive carrier like spirooxazine through electrostatic interaction between phenylalanine and spirooxazine derivative. Thus, the spirooxazine is expected to form a UV-addressable phenylalanine sensing interface. In this study, we prepared phenylalanine sensing interface of a spirooxazine derivative by self-assembly technique and evaluated interaction between a spirooxazine moiety and phenylalanine with a surface plasmon resonance (SPR). The refractive index change of monolayer caused by interaction between a spirooxazine derivative and phenylalanine led to the SPR angle shifts upon UV irradiation. The SPR angle shift increased with increasing the concentration of phenylalanine solution. These results indicated that the spirooxazine derivative self-assembled monolayer (SAM) has an application potential for UV-addressable phenylalanine sensing

  8. Abnormal levels of UV-induced unscheduled DNA synthesis in ataxia telangiectasia cells after exposure to ionizing radiation

    International Nuclear Information System (INIS)

    Jaspers, N.G.J.; Nederlandse Centrale Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek, Rijswijk. Medical Biological Lab.); Bootsma, D.

    1982-01-01

    In cultured cells from normal individuals and from patients having ataxia telangiectasia (AT) the rate of unscheduled DNA synthesis (UDS) induced by UV light was investigated by autoradiography. The number of grains in 6 different AT cell strains was similar to that observed in normal cells. Exposure of normal cells to doses of X-rays up to 20 krad had no influence on the rate of UV-induced UDS. In contrast, the UV-induced UDS was significantly modified in AT cells by treatment with X-rays. In AT cell strains that were reported to have reduced levels of γ-ray-induced repair DNA synthesis ('excision-deficient' AT cells) the effect of X-rays on UV-induced UDS was inhibitory, whereas UV-induced UDS was stimulated by X-ray exposure in 'excision-proficient' AT cell strains. Different UV and X-ray dose-response relationships were seen in the two categories of AT cell strains. (orig./AJ)

  9. Long-term structural canopy changes sustain net photosynthesis per ground area in high arctic Vaccinium uliginosum exposed to changes in near-ambient UV-B levels

    DEFF Research Database (Denmark)

    Boesgaard, Kristine Stove; Albert, Kristian Rost; Ro-Poulsen, Helge

    2012-01-01

    Full recovery of the ozone layer is not expected for several decades and consequently, the incoming level of solar ultraviolet-B (UV-B) will only slowly be reduced. Therefore to investigate the structural and photosynthetic responses to changes in solar UV-B we conducted a 5-year UV-B exclusion s...

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

    International Nuclear Information System (INIS)

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

    1988-09-01

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

  11. Differences in the levels of UV repair and in clinical symptoms in two sibs affected by xeroderma pigmentosum

    Energy Technology Data Exchange (ETDEWEB)

    Stefanini, M; Nuzzo, F [Consiglio Nazionale delle Ricerche, Pavia (Italy). Lab. di Genetica Biochimica ed Evoluzionistica; Keijzer, W [Erasmus Universiteit, Rotterdam (Netherlands). Dept. of Cell Biology and Genetics; Dalpra, L [Milan Univ. (Italy). Istituto di Biologia; Elli, R; Nicoletti, B [Rome Univ. (Italy). Ist. di Biologia Generale 1; Nazzaro Porro, M [Ospedale Dermatologico S. Gallicano, Rome (Italy)

    1980-01-01

    UV-repair activity was studied in two sibs affected by XP showing different clinical symptoms. Complementation studies indicated that both patients fit into complementation group A. The levels of UV-induced /sup 3/H-thymidine incorporation, in fibroblasts and in lymphocytes, are different in the two patients: residual level of repair DNA synthesis in the sister is higher than in the brother. In one of the cell samples analyzed UDS analysis showed that in the sister a low proportion of cells with normal repair synthesis is present.

  12. Selective surface functionalization of polystyrene induced by synchrotron or UV radiation in the presence of oxygen or acrylic acid vapors

    International Nuclear Information System (INIS)

    Kessler, Felipe; Kuhn, Sidiney; Weibel, Daniel E.

    2009-01-01

    Efficient surface functionalization of Polystyrene (PS) thin films by electromagnetic radiation in combination with a reactive gaseous atmosphere was obtained. Monochromatic synchrotron (SR) or polychromatic UV radiation were used as excitation sources. When SR was used, O 2 was introduced after irradiation into the UHV chamber. UV irradiation was carried out keeping a constant flow of O 2 or acrylic acid (AA) vapors during the photolysis. FTIR-ATR and XPS-NEXAFS spectra were obtained at the UFRGS and the LNLS, Campinas respectively. PS films were functionalized by monochromatic SR and then expose to O 2 at specific transitions such us C 1s →σ * C-C excitation. It was found a high rate of COO, C=O and C-O groups at the surface (> 70%). UV-assisted treatment in the presence of AA vapors showed that an efficient polymerization process took place, such as, it was observed in previous AA low pressure RF plasma treatments. UV-assisted functionalization has the advantage of lower costs and simple set-up compared to plasma treatments. (author)

  13. Impacts of Brown Carbon from Biomass Burning on Surface UV and Ozone Photochemistry in the Amazon Basin

    Science.gov (United States)

    Mok, Jungbin; Krotkov, Nickolay A.; Arola, Antti; Torres, Omar; Jethva, Hiren; Andrade, Marcos; Labow, Gordon; Eck, Thomas F.; Li, Zhangqing; Dickerson, Russell R.; hide

    2016-01-01

    The spectral dependence of light absorption by atmospheric particulate matter has major implications for air quality and climate forcing, but remains uncertain especially in tropical areas with extensive biomass burning. In the September-October 2007 biomass-burning season in Santa Cruz, Bolivia, we studied light absorbing (chromophoric) organic or brown carbon (BrC) with surface and space-based remote sensing. We found that BrC has negligible absorption at visible wavelengths, but significant absorption and strong spectral dependence at UV wavelengths. Using the ground-based inversion of column effective imaginary refractive index in the range 305368nm, we quantified a strong spectral dependence of absorption by BrC in the UV and diminished ultraviolet B (UV-B) radiation reaching the surface. Reduced UV-B means less erythema, plant damage, and slower photolysis rates. We use a photochemical box model to show that relative to black carbon (BC) alone, the combined optical properties of BrC and BC slow the net rate of production of ozone by up to 18 and lead to reduced concentrations of radicals OH, HO2, and RO2 by up to 17, 15, and 14, respectively. The optical properties of BrC aerosol change in subtle ways the generally adverse effects of smoke from biomass burning.

  14. Impacts of brown carbon from biomass burning on surface UV and ozone photochemistry in the Amazon Basin

    KAUST Repository

    Mok, Jungbin

    2016-11-11

    The spectral dependence of light absorption by atmospheric particulate matter has major implications for air quality and climate forcing, but remains uncertain especially in tropical areas with extensive biomass burning. In the September-October 2007 biomass-burning season in Santa Cruz, Bolivia, we studied light absorbing (chromophoric) organic or “brown” carbon (BrC) with surface and space-based remote sensing. We found that BrC has negligible absorption at visible wavelengths, but significant absorption and strong spectral dependence at UV wavelengths. Using the ground-based inversion of column effective imaginary refractive index in the range 305–368 nm, we quantified a strong spectral dependence of absorption by BrC in the UV and diminished ultraviolet B (UV-B) radiation reaching the surface. Reduced UV-B means less erythema, plant damage, and slower photolysis rates. We use a photochemical box model to show that relative to black carbon (BC) alone, the combined optical properties of BrC and BC slow the net rate of production of ozone by up to 18% and lead to reduced concentrations of radicals OH, HO2, and RO2 by up to 17%, 15%, and 14%, respectively. The optical properties of BrC aerosol change in subtle ways the generally adverse effects of smoke from biomass burning.

  15. Inhibition of charge recombination for enhanced dye-sensitized solar cells and self-powered UV sensors by surface modification

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Liang, E-mail: chuliang@njupt.edu.cn [Advanced Energy Technology Center, Nanjing University of Posts and Telecommunications (NUPT), Nanjing 210046 (China); Wuhan National Laboratory for Optoelectronics (WNLO)-School of Physics, Huazhong University of Science and Technology (HUST), Wuhan 430074 (China); Qin, Zhengfei; Liu, Wei [School of Materials Science and Engineering (SMSE), Nanjing University of Posts and Telecommunications (NUPT), Nanjing 210046 (China); Ma, Xin’guo, E-mail: maxg2013@sohu.com [Hubei Collaborative Innovation Center for High-efficiency Utilization of Solar Energy, Hubei University of Technology, Wuhan 430068 (China)

    2016-12-15

    Graphical abstract: Inhibition of charge recombination was utilized to prolong electrode lifetime in dye-sensitized solar cells (DSSCs) and self-powered UV sensors based on TiO{sub 2}-modified SnO{sub 2} photoelectrodes. The electrochemical impedance spectroscopy and open-circuit voltage decay measurements indicated that the electron lifetime was significantly prolonged in DSSCs after TiO{sub 2} modification. And in self-powered UV sensors, the sensitivity and response time were enhanced. - Highlights: • The surface modification to inhibit charge recombination was utilized in photovoltaic devices. • Inhibition of charge recombination can prolong electrode lifetime in photovoltaic devices. • Enhanced DSSCs and self-powered UV sensors based on SnO{sub 2} photoelectrodes were obtained by TiO{sub 2} modification. - Abstract: The surface modification to inhibit charge recombination was utilized in dye-sensitized solar cells (DSSCs) and self-powered ultraviolet (UV) sensors based on SnO{sub 2} hierarchical microspheres by TiO{sub 2} modification. For DSSCs with SnO{sub 2} photoelectrodes modified by TiO{sub 2}, the power conversion efficiency (PCE) was improved from 1.40% to 4.15% under standard AM 1.5G illumination (100 mW/cm{sup 2}). The electrochemical impedance spectroscopy and open-circuit voltage decay measurements indicated that the charge recombination was effectively inhibited, resulting in long electron lifetime. For UV sensors with SnO{sub 2} photoelectrodes modified by TiO{sub 2} layer, the self-powered property was more obvious, and the sensitivity and response time were enhanced from 91 to 6229 and 0.15 s to 0.055 s, respectively. The surface modification can engineer the interface energy to inhibit charge recombination, which is a desirable approach to improve the performance of photoelectric nanodevice.

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

    CERN Document Server

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

    1988-01-01

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

  17. Passive New UV Polarimeter for Remote Surface and Atmospheric Sensing, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Our imaging polarimeter concept makes available for the first time, the passive remote imagery of all four Stokes vector components at UV wavelengths shorter than...

  18. A fast determination of nitrate in rain and surface waters by means of UV spectrophotometry

    International Nuclear Information System (INIS)

    Slanina, J.; Lingerak, W.A.; Bergman, L.

    1976-01-01

    Organic substances are the main interference in the direct U.V. spectrophotometric determination of nitrate at 210 nm. An active carbon filter (Filopur) is therefore proposed which adsorbs all organic interferences. With this filter the U.V. spectrophotometric method gives the same results as the Na-salicylate method. The reproducibility is generally better than 5%. One determination takes 50 s. (orig.) [de

  19. Monolayer alignment on azobenzene surfaces during UV light irradiation: Analysis of optical polarized absorption measurement results and theoretical treatment

    International Nuclear Information System (INIS)

    Zakharov, A.V.; Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa

    2006-01-01

    The influence of the charge separation during the trans-cis conformational change on the surface of azobenzene 6Az10PVA monolayer on the polar liquid-crystal monolayer film, such as 4-n-pentyl-4 ' -cyanobiphenyl(5CB), is investigated. The effective anchoring energy (in the Rapini-Papolar form) is phenomenologically described in the framework of the molecular model, which takes into account the interaction between the surface polarization and surface electric field, for number of conformational states of the boundary surface. It is shown, using the experimental data for the voltage across the 6Az10PVA+5CB film, provided by the surface-potential technique, that the charge separation during the conformational changing, caused by the UV irradiation, may lead to changing of the surface alignment of liquid-crystalline molecules. The influence of the photoisomerization process on the orientational order parameter S 2 (t) using the optical polarized absorption measurement is also investigated

  20. Utilization of the UV laser with picosecond pulses for the formation of surface microstructures on elastomeric plastics

    Science.gov (United States)

    Antoszewski, B.; Tofil, S.; Scendo, M.; Tarelnik, W.

    2017-08-01

    Elastomeric plastics belong to a wide range of polymeric materials with special properties. They are used as construction material for seals and other components in many branches of industry and, in particular, in the biomedical industry, mechatronics, electronics and chemical equipment. The micromachining of surfaces of these materials can be used to build micro-flow, insulating, dispensing systems and chemical and biological reactors. The paper presents results of research on the effects of micro-machining of selected elastomeric plastics using a UV laser emitting picosecond pulses. The authors see the prospective application of the developed technology in the sealing technique in particular to shaping the sealing pieces co-operating with the surface of the element. The result of the study is meant to show parameters of the UV laser’s performance when producing typical components such as grooves, recesses for optimum ablation in terms of quality and productivity.

  1. Surface modification of poly(tetrafluoroethylene) films by low energy Ar+ ion-beam activation and UV-induced graft copolymerization

    International Nuclear Information System (INIS)

    Zhang Yan; Huan, A.C.H.; Tan, K.L.; Kang, E.T.

    2000-01-01

    Surface modification of poly(tetrafluoroethylene) (PTFE) films by Ar + ion-beam irradiation with varying ion energy and ion dose was carried out. The changes in surface composition of the irradiated PTFE films were characterized, both in situ and after exposure to air, by X-ray photoelectron spectroscopy (XPS). The possible mechanisms of chemical reaction induced by the incident ion beam on the surface of PTFE film included defluorination, chain scission and cross-linking, as indicated by the presence of the characteristic peak components associated with the - - -CF 3 , - - -CF, and C(CF 2 ) 4 species in the C 1s core-level spectra, the decrease in surface [F]/[C] ratio, and the increase in surface micro-hardness of the Ar + ion-beam-treated PTFE films. Furthermore, the free radicals generated by the ion-beam could react with oxygen in the air to give rise to oxidized carbon species, such as the peroxides, on the PTFE surface. Thus, after exposure to air, the Ar + ion-beam-pretreated PTFE films were susceptible to further surface modification by UV-induced graft copolymerization with a vinyl monomer, such as acrylamide (AAm). The graft concentrations were deduced from the XPS-derived surface stoichiometries. The Ar + ion energy and the ion dose affected not only the surface composition of the treated films but also the graft copolymerization efficiency of the corresponding pretreated films

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

    Science.gov (United States)

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

    2014-12-15

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

  3. Investigation of γ-(2,3-Epoxypropoxypropyltrimethoxy Silane Surface Modified Layered Double Hydroxides Improving UV Ageing Resistance of Asphalt

    Directory of Open Access Journals (Sweden)

    Canlin Zhang

    2017-01-01

    Full Text Available γ-(2,3-Epoxypropoxypropyltrimethoxy silane surface modified layered double hydroxides (KH560-LDHs were prepared and used to improve the ultraviolet ageing resistance of asphalt. The results of X-ray photoelectron spectrometry (XPS indicated that KH560 has been successfully grafted onto the surface of LDHs. The agglomeration of LDHs particles notably reduced after KH560 surface modification according to scanning electron microscopy (SEM, which implied that the KH560 surface modification was helpful to promote the dispersibility of LDHs in asphalt. Then, the influence of KH560-LDHs and LDHs on the physical and rheological properties of asphalt before and after UV ageing was thoroughly investigated. The storage stability test showed that the difference in softening point (ΔS of LDHs modified asphalt decreased from 0.6 °C to 0.2 °C at an LDHs content of 1% after KH560 surface modification, and the tendency became more pronounced with the increase of LDH content, indicating that KH560 surface modification could improve the stability of LDHs in asphalt. After UV ageing, the viscous modulus (G’’ of asphalt significantly reduced, and correspondingly, the elastic modulus (G’ and rutting factor (G*/sin δ rapidly increased. Moreover, the asphaltene increased and the amount of “bee-like” structures of the asphalt decreased. Compared with LDHs, KH560-LDHs obviously restrained performance deterioration of the asphalt, and helped to relieve the variation of the chemical compositions and morphology of asphalt, which suggested that the improvement of KH560-LDHs on UV ageing resistance of asphalt was superior to LDHs.

  4. Parallel increases in sister chromatid exchanges at base level and with UV treatment in human opiate users

    International Nuclear Information System (INIS)

    Shafer, D.A.; Falek, A.; Madden, J.J.; Tadayon, F.; Pline, M.; Kuehnle, J.C.; Mendelson, J.

    1983-01-01

    The SCE base level frequency and SCE levels induced by far-UV (254 nm) treatment of cells in early G 1 and early S phases of the cell cycle were significantly higher in leukocytes from heroin addicts as compared to controls. The increased SCE levels in addicts was greatest at base level and smallest after UV irradiation of cells in S phase. These results corrobate and extend our previous findings of increased chromosome damage and reduced DNA-repair synthesis in heroin users. Since opiates do not directly damage DNA, the elevated cytogenetic effects associated with opiate use probably arise from secondary promotional effects related to opiate-mediated alterations in leukocyte metabolism. (orig.)

  5. Detection of Explosives on Surfaces Using UV Raman Spectroscopy: Effect of Substrate Color

    Science.gov (United States)

    2017-10-01

    257.23-nm excitation (25 mW at the laser) using 2.5-s integration time and 100 accumulations. Each spectrum is offset by 400 counts from the one...tens of meters have been reported. The testing of UV Raman spectroscopy systems for standoff UV Raman spectroscopy has been generally limited to bare...SP2500A 500-mm focal length monochromator and a PIXIS 400 × 3048 pixel charge-coupled device (CCD) camera (Princeton Instruments, Trenton, NJ). An

  6. Survey for Life-related Species During a Planetary Surface Exploration; System Type I - UV Stimulated Fluorescent Sensor

    Science.gov (United States)

    Wang, Alian; Haskin, L. A.; Gillis, J. J.

    2003-01-01

    The widely accepted minimum requirements for life on Earth include the presence of water and accessible sources of carbon. We assume that the same criteria must hold for putative life on past or present Mars. The evidence for CO2 and H2O at or near the Martian surface, carbon in Martian meteorites, aqueous alteration, and probable hydrothermal activity suggest that conditions conducive to the origin and evolution of life on Mars may have existed for long periods of time and may still obtain at present. Surface exploration on Mars that enables the direct detection of water in minerals and of organic carbon (including not just organic and biogenic materials but their degradation products such as kerogen-like hydrocarbons and graphitized carbon) that might be products or residues of biologic activity, is crucial. The search for evidence of life, past or present, will nevertheless be difficult. The lack of direct evidence for organic carbon and the low amounts of water found in the soils at the Viking sites demonstrated the difficulties. Recent results of GRS experiment of Odyssey mission indicated the existence of abundant water ice beneath the Mars surface. Mineralogical evidence for the presence of carbonate, sulfates, or clay minerals, products of weathering and aqueous deposition, have not been identified unambiguously on Mars. Rocks such as shales and, more particularly, limestones, which we associate with moist and benign environments on Earth, are evidently not abundant. Presumably, then, neither were the photosynthetic organisms that might have produced them. In addition, the harsh present environment on Mars (e.g., dryness, low temperatures, large temperature cycles, high level of UV light on the surface, frequent dust storms, etc.) can both destroy carbon- and water-bearing materials and hide them. Therefore, directly detecting life-related materials on Mars was likened to seeking and examining proverbial needles in haystacks. We argue that survey type

  7. Anthropogenic changes in the surface all-sky UV-B radiation through 1850-2005 simulated by an Earth system model

    Science.gov (United States)

    Watanabe, S.; Takemura, T.; Sudo, K.; Yokohata, T.; Kawase, H.

    2012-06-01

    The historical anthropogenic change in the surface all-sky UV-B (solar ultraviolet: 280-315 nm) radiation through 1850-2005 is evaluated using an Earth system model. Responses of UV-B dose to anthropogenic changes in ozone and aerosols are separately evaluated using a series of historical simulations including/excluding these changes. Increases in these air pollutants cause reductions in UV-B transmittance, which occur gradually/rapidly before/after 1950 in and downwind of industrial and deforestation regions. Furthermore, changes in ozone transport in the lower stratosphere, which is induced by increasing greenhouse gas concentrations, increase ozone concentration in the extratropical upper troposphere and lower stratosphere. These transient changes work to decrease the amount of UV-B reaching the Earth's surface, counteracting the well-known effect increasing UV-B due to stratospheric ozone depletion, which developed rapidly after ca. 1980. As a consequence, the surface UV-B radiation change between 1850 and 2000 is negative in the tropics and NH extratropics and positive in the SH extratropics. Comparing the contributions of ozone and aerosol changes to the UV-B change, the transient change in ozone absorption of UV-B mainly determines the total change in the surface UV-B radiation at most locations. On the other hand, the aerosol direct and indirect effects on UV-B play an equally important role to that of ozone in the NH mid-latitudes and tropics. A typical example is East Asia (25° N-60° N and 120° E-150° E), where the effect of aerosols (ca. 70%) dominates the total UV-B change.

  8. Biodegradation improvement of poly(3-hydroxy-butyrate) films by entomopathogenic fungi and UV-assisted surface functionalization.

    Science.gov (United States)

    Kessler, Felipe; Marconatto, Leticia; Rodrigues, Roberta da Silva Bussamara; Lando, Gabriela Albara; Schrank, Augusto; Vainstein, Marilene Henning; Weibel, Daniel Eduardo

    2014-01-05

    Ultraviolet (UV)-assisted surface modification in the presence of oxygen was used as initial step to achieve controlled degradation of poly(3-hydroxy-butyrate), PHB, films by entomopathogenic fungi. Treated surfaces were investigated by surface analysis techniques (water contact angle, Fourier Transformed Infrared Spectroscopy in Attenuated Total Reflectance mode, X-ray Photoelectron Spectroscopy, Near-edge X-ray Absorption Fine Structure, Gel Permeation Chromatography, Optical Microscopy, Scanning Electron Microscopy, and weight loss). After the UV-assisted treatments, new carbonyl groups in new chemical environments were detected by XPS and NEXAFS spectroscopy. The oxidizing atmosphere did not allow the formation of CC bonds, indicating that Norrish Type II mechanism is suppressed during or by the treatments. The higher hydrophilicity and concentration of oxygenated functional groups at the surface of the treated films possibly improved the biodegradation of the films. It was observed a clear increase in the growth of this fungus when oxygenated groups were grafted on the polymers surfaces. This simple methodology can be used to improve and control the degradation rate of PHB films in applications that require a controllable degradation rate. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. [Control levels of Sin3 histone deacetylase for spontaneous and UV-induced mutagenesis in yeasts Saccharomyces cerevisiae].

    Science.gov (United States)

    Lebovka, I Iu; Kozhina, T N; Fedorova, I V; Peshekhonov, V T; Evstiukhina, T A; Chernenkov, A Iu; Korolev, V G

    2014-01-01

    SIN3 gene product operates as a repressor for a huge amount of genes in Saccharomyces cerevisiae. Sin3 protein with a mass of about 175 kDa is a member of the RPD3 protein complex with an assessed mass of greater than 2 million Da. It was previously shownthat RPD3 gene mutations influence recombination and repair processes in S. cerevisiae yeasts. We studied the impacts of the sin3 mutation on UV-light sensitivity and UV-induced mutagenesis in budding yeast cells. The deletion ofthe SIN3 gene causes weak UV-sensitivity of mutant budding cells as compared to the wild-type strain. These results show that the sin3 mutation decreases both spontaneous and UV-induced levels of levels. This fact is hypothetically related to themalfunction of ribonucleotide reductase activity regulation, which leads to a decrease in the dNTP pool and the inaccurate error-prone damage bypass postreplication repair pathway, which in turn provokes a reduction in the incidence of mutations.

  10. Laguerre-Gauss beam generation in IR and UV by subwavelength surface-relief gratings

    DEFF Research Database (Denmark)

    Vertchenko, Larissa; Shkondin, Evgeniy; Malureanu, Radu

    2017-01-01

    layerdepositions and dry etch techniques. We exploit the phenomenon of formbirefringence to give rise to the spin-to-orbital angular momentum conversion.We demonstrate that these plates can generate beams with high quality for theUV and IR range, allowing them to interact with high power laser sources orinside...... laser cavities....

  11. A near-UV-converted LiMgBO3:Dy3+ nanophosphor: Surface and spectral investigations

    International Nuclear Information System (INIS)

    Bedyal, A.K.; Kumar, Vinay; Prakash, Ram; Ntwaeaborwa, O.M.; Swart, H.C.

    2015-01-01

    Graphical abstract: - Highlights: • Combustion method was employed to synthesize LiMgBO 3 :Dy 3+ nanophosphors. • The phosphor can be efficiently excited by near-UV chips. • XPS was done to investigate the chemical constitution and chemical bonding state of elements in the LiMgBO 3 : Dy 3+ nanophosphor. • The calculated CIE coordinates (0.45, 0.46) were found to be in the white spectrum region. - Abstract: A near-ultra violet (UV) converted LiMgBO 3 :Dy 3+ nanophosphors have been synthesized by the combustion method. The structural, spectral and optical properties were examined by powder X-ray diffraction, fluorescent spectrophotometry and UV–vis spectroscopy. The excitation spectra of the phosphors contain sharp peaks at 294, 323, 348 and 385 nm due to the 4f–4f transition of the Dy 3+ ion. The phosphor is efficiently excited by near-UV chips. Upon near-UV excitation the phosphor emits intense blue and yellow with a weak red band centered at 484, 573 and 669 nm respectively, ascribed to the transition of Dy 3+ ion from 4 F 9/2 → 6 H 15/2 , 6 H 13/2 , 6 H 11/2 . The diffuse reflectance spectra of the phosphors were consistent with the excitation spectra and were used to calculate the band gap of the material, approximated to be 5.4 eV. The calculated CIE coordinates (0.45, 0.46) under 348 nm excitation were found to be in the white spectrum region. For surface investigation, X-ray photoelectron spectroscopy was used which confirms the presence of all the elements on the surface of the material

  12. Validation of an HPLC-UV method for the determination of ceftriaxone sodium residues on stainless steel surface of pharmaceutical manufacturing equipments.

    Science.gov (United States)

    Akl, Magda A; Ahmed, Mona A; Ramadan, Ahmed

    2011-05-15

    In pharmaceutical industry, an important step consists in the removal of possible drug residues from the involved equipments and areas. The cleaning procedures must be validated and methods to determine trace amounts of drugs have, therefore, to be considered with special attention. An HPLC-UV method for the determination of ceftriaxone sodium residues on stainless steel surface was developed and validated in order to control a cleaning procedure. Cotton swabs, moistened with extraction solution (50% water and 50% mobile phase), were used to remove any residues of drugs from stainless steel surfaces, and give recoveries of 91.12, 93.8 and 98.7% for three concentration levels. The precision of the results, reported as the relative standard deviation (RSD), were below 1.5%. The method was validated over a concentration range of 1.15-6.92 μg ml(-1). Low quantities of drug residues were determined by HPLC-UV using a Hypersil ODS 5 μm (250×4.6 mm) at 50 °C with an acetonitrile:water:pH 7:pH 5 (39-55-5.5-0.5) mobile phase at flow rate of 1.5 ml min(-1), an injection volume of 20 μl and were detected at 254 nm. A simple, selective and sensitive HPLC-UV assay for the determination of ceftriaxone sodium residues on stainless steel surfaces was developed, validated and applied. Copyright © 2011 Elsevier B.V. All rights reserved.

  13. [Effect of UV-radiation on the level of ascorbic acid, SH-groups, and activity of glutathione reductase in the eye lens].

    Science.gov (United States)

    Byshneva, L N; Senchuk, V V

    2002-01-01

    The effect of UV radiation in vitro on the level of ascorbate, SH-groups and glutathione reductase activity in the soluble fraction of bovine eye lens was studied. UV-Irradiation increased NADPH-oxidoreductase activity, the level of ascorbate oxidation and decreased the content of SH-groups and activity of glutathione reductase. Significant activation of the NADPH-oxidoreductase activity in the presence of ascorbate and Cu2+ was observed after UV-irradiation. It is suggested that ascorbate may play an important role in the UV-induced lens pathology.

  14. Detection of silver nanoparticles in seawater at ppb levels using UV-visible spectrophotometry with long path cells.

    Science.gov (United States)

    Lodeiro, Pablo; Achterberg, Eric P; El-Shahawi, Mohammad S

    2017-03-01

    Silver nanoparticles (AgNPs) are emerging contaminants that are difficult to detect in natural waters. UV-visible spectrophotometry is a simple technique that allows detection of AgNPs through analysis of their characteristic surface plasmon resonance band. The detection limit for nanoparticles using up to 10cm path length cuvettes with UV-visible spectrophotometry is in the 0.1-10ppm range. This detection limit is insufficiently low to observe AgNPs in natural environments. Here we show how the use of capillary cells with an optical path length up to 200cm, forms an excellent technique for rapid detection and quantification of non-aggregated AgNPs at ppb concentrations in complex natural matrices such as seawater. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. A constitutive damage specific DNA-binding protein is synthesized at higher levels in UV-irradiated primate cells

    International Nuclear Information System (INIS)

    Hirschfeld, S.; Levine, A.S.; Ozato, K.; Protic, M.

    1990-01-01

    Using a DNA band shift assay, we have identified a DNA-binding protein complex in primate cells which is present constitutively and has a high affinity for UV-irradiated, double-stranded DNA. Cells pretreated with UV light, mitomycin C, or aphidicolin have higher levels of this damage-specific DNA-binding protein complex, suggesting that the signal for induction can either be damage to the DNA or interference with cellular DNA replication. Physiochemical modifications of the DNA and competition analysis with defined substrates suggest that the most probable target site for the damage-specific DNA-binding protein complex is a 6-4'-(pyrimidine-2'-one)-pyrimidine dimer: specific binding could not be detected with probes which contain -TT- cyclobutane dimers, and damage-specific DNA binding did not decrease after photoreactivation of UV-irradiated DNA. This damage-specific DNA-binding protein complex is the first such inducible protein complex identified in primate cells. Cells from patients with the sun-sensitive cancer-prone disease, xeroderma pigmentosum (group E), are lacking both the constitutive and the induced damage-specific DNA-binding activities. These findings suggest a possible role for this DNA-binding protein complex in lesion recognition and DNA repair of UV-light-induced photoproducts

  16. Improvement of thermal stability of UV curable pressure sensitive adhesive by surface modified silica nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Pang, Beili; Ryu, Chong-Min; Kim, Hyung-Il, E-mail: hikim@cnu.ac.kr

    2013-11-01

    Highlights: • Silica nanoparticles were modified to carry the vinyl groups for photo-crosslinking. • Acrylic copolymer was modified to have the vinyl groups for photo-crosslinking. • Strong and extensive interfacial bondings were formed between polymer and silica. • Thermal stability of PSA was improved by forming nanocomposite with modified silica. -- Abstract: Pressure sensitive adhesives (PSAs) with higher thermal stability were successfully prepared by forming composite with the silica nanoparticles modified via reaction with 3-methacryloxypropyltrimethoxysilane. The acrylic copolymer was synthesized as a base resin for PSAs by solution polymerization of 2-EHA, EA, and AA with AIBN as an initiator. The acrylic copolymer was further modified with GMA to have the vinyl groups available for UV curing. The peel strength decreased with the increase of gel content which was dependent on both silica content and UV dose. Thermal stability of the composite PSAs was improved noticeably with increasing silica content and UV dose mainly due to the strong and extensive interfacial bonding between the organic polymer matrix and silica.

  17. The influence of surface topography of UV coated and printed cardboard on the print gloss

    OpenAIRE

    Igor Karlović; Dragoljub Novaković; Erzsébet Novotny

    2010-01-01

    The incident light on the printed surface undergoes through several processes of scattering, absorbtion and reflectiondepending on the surface topography and structure of the material. The specular part of the surface reflection is commonlyattributed as the geometric component of the reflection, and when measured is associated with specular gloss.The diffuse part of the surface reflection contains the chromatic part of the reflection and is commonly calculatedthrough colorimetric values. Usin...

  18. Studies on cationic UV curing of epoxidised palm oil (EPO) for surface coatings

    International Nuclear Information System (INIS)

    Mek Zah Salleh; Mohd Hilmi Mahmood; Wan Rosli Wan Daud; Kumar, R.N.

    2000-01-01

    Epoxidised palm oil (EPO) resin can be cured by ultraviolet (UV) radiation either by radical, cationic or hybrid system. Cationic curing system has been chosen in this study due to the fact that epoxy groups present in EPO can be utilised directly to form crosslinking. Curing was done by means of a 20 cm wide UV IST machine with the conditions of 7.5 A current and 4 m/min conveyor speed. Sulphonium and ferrocenium salts were used as cationic photoinitiator. A formulations study was performed on the selected grades of EPO with other materials. These include types and concentration of photoinitiator, monomers, concentration of EPO and post-cure. The properties of the cured film such as pendulum hardness, percentage of gel content and tensile strength were determined. It was found that triarylsulphonium hexafluorophosphate has a very low solubility in EPO. Addition of vinyl ether monomer to the formulation did not enhance pendulum hardness and gel content of the cured films. It is also found that the post cure temperature has no significant effect on the cured film

  19. Femtosecond UV laser non-ablative surface structuring of ZnO crystal: impact on exciton photoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Museur, Luc [Laboratoire de Physique des Lasers (LPL), UMR 7538 CNRS, Institut Galilee, Universite Paris 13, 93430 Villetaneuse (France); Michel, Jean-Pierre [Laboratoire des Proprietes Mecaniques et Thermodynamiques des Materiaux (LPMTM), UMR 9001 CNRS, Institut Galilee, Universite Paris 13, 93430 Villetaneuse (France); Portes, Patrick; Kanaev, Andrei V. [Laboratoire d' Ingenierie des Materiaux et des Hautes Pressions (LIMHP), UMR 1311 CNRS, Institut Galilee, Universite Paris 13, 93430 Villetaneuse (France); Englezis, Apostolis; Stassinopoulos, Andreas; Anglos, Demetrios [Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas (IESL-FORTH), 71110 Heraklion, Crete (Greece)

    2010-03-15

    The ultraviolet (UV) laser irradiation (248 nm) of monocrystalline wurtzite ZnO with 450 fs pulses results in surface modification. A formation of two orthogonal ripple structures with a period of 400-500 nm was observed oriented parallel and perpendicular to the laser beam polarization. The UV exciton emission obtained on the irradiated domains is found greatly enhanced locally up to {approx}10{sup 3} times. The photoluminescence band is redshifted by 2-3 nm and 40% narrower (full width at half-maximum), while at the same time the E{sub 2} (439 cm{sup -1}) Raman band intensity increases up to {approx}50 times. The process is found irreversible with the threshold fluence of 11 mJ/cm{sup 2}, which is considerably lower than the ablation threshold 115 mJ/cm{sup 2}. Fine surface nanostructuring on the scale of {approx}10 nm may be responsible for the observed effect. (c) 2008 Optical Society of America.

  20. Fermi level on hydrogen terminated diamond surfaces

    Czech Academy of Sciences Publication Activity Database

    Rezek, Bohuslav; Saurer, C.; Nebel, C. E.; Stutzmann, M.; Ristein, J.; Ley, L.; Snidero, E.; Bergonzo, P.

    2003-01-01

    Roč. 82, č. 14 (2003), s. 2266-2268 ISSN 0003-6951 EU Projects: European Commission(XE) HPRN-CT-1999-00139 Grant - others:DFC(DE) NE524-2 Institutional research plan: CEZ:AV0Z1010914 Keywords : atomic force microscope (AFM) * Kelvin probe experiments * diamond surface Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.049, year: 2003

  1. Individual IOL Surface Topography Analysis by the WaveMaster Reflex UV

    Directory of Open Access Journals (Sweden)

    Marc Kannengießer

    2013-01-01

    Full Text Available Purpose. In order to establish inspection routines for individual intraocular lenses (IOLs, their surfaces have to be measured separately. Currently available measurement devices lack this functionality. The purpose of this study is to evaluate a new topography measurement device based on wavefront analysis for measuring individual regular and freeform IOL surfaces, the “WaveMaster Reflex UV” (Trioptics, Wedel, Germany. Methods. Measurements were performed on IOLs with increasingly complex surface geometries: spherical surfaces, surfaces modelled by higher-order Zernike terms, and freeform surfaces from biometrical patient data. Two independent parameters were measured: the sample’s radius of curvature (ROC and its residual (difference of sample topography and its best-fit sphere. We used a quantitative analysis method by calculating the residuals’ root-mean-square (RMS and peak-to-Valley (P2V values. Results. The sample’s best-fit ROC differences increased with the sample’s complexity. The sample’s differences of RMS values were 80 nm for spherical surfaces, 97 nm for higher-order samples, and 21 nm for freeform surfaces. Graphical representations of both measurement and design topographies were recorded and compared. Conclusion. The measurements of spherical surfaces expectedly resulted in better values than those of freeform surfaces. Overall, the wavefront analysing method proves to be an effective method for evaluating individual IOL surfaces.

  2. Laser- and UV-assisted modification of polystyrene surfaces for control of protein adsorption and cell adhesion

    International Nuclear Information System (INIS)

    Pfleging, Wilhelm; Torge, Maika; Bruns, Michael; Trouillet, Vanessa; Welle, Alexander; Wilson, Sandra

    2009-01-01

    An appropriate choice of laser and process parameters enables new approaches for the fabrication of polymeric lab-on-chip devices with integrated functionalities. We will present our current research results in laser-assisted modification of polystyrene (PS) with respect to the fabrication of polymer devices for cell culture applications. For this purpose laser micro-patterning of PS and subsequent surface functionalization was investigated as function of laser and process parameters. A high power ArF-excimer laser radiation source with a pulse length of 19 ns as well as a high repetition ArF-excimer laser source with a pulse length of 5 ns were used in order to study the influence of laser pulse length on laser-induced surface oxidation. The change in surface chemistry was characterized by X-ray photoelectron spectroscopy and contact angle measurements. The difference between laser-assisted modification versus UV-lamp assisted modification was investigated. A photolytic activation of specific areas of the polymer surface and subsequent oxidization in oxygen or ambient air leads to a chemically modified polymer surface bearing carboxylic acid groups well-suited for controlled competitive protein adsorption or protein immobilization. Finally, distinct areas for cell growth and adhesion are obtained

  3. UV sensitivity of planktonic net community production in ocean surface waters

    OpenAIRE

    Regaudie de Gioux, Aurore; Agustí, Susana; Duarte, Carlos M.

    2014-01-01

    The net plankton community metabolism of oceanic surface waters is particularly important as it more directly affects the partial pressure of CO2 in surface waters and thus the air-sea fluxes of CO2. Plankton communities in surface waters are exposed to high irradiance that includes significant ultraviolet blue (UVB, 280-315 nm) radiation. UVB radiation affects both photosynthetic and respiration rates, increase plankton mortality rates, and other metabolic and chemical processes. Here we tes...

  4. Polymer surface modification using UV treatment for attachment of natamycin and the potential applications for conventional food cling wrap (LDPE)

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Joongmin, E-mail: shinj@uwstout.edu [Engineering and Technology, University of Wisconsin-Stout, Menomonie, WI, 54751 (United States); Liu, Xiaojing [Mechanical and Electronic Engineering, Wuhan University of Technology, Wuhan (China); Chikthimmah, Naveen [Food Science and Technology, University of Wisconsin-Stout, Menomonie, WI, 54751 (United States); Lee, Youn Suk [Department of Packaging, Yonsei University, Gangwon 220-710 (Korea, Republic of)

    2016-11-15

    Highlights: • The study suggests an optimized method for UV-induced antimicrobial agents grafting on LDPE. • The study evaluated the effective of various solvents for acrylic acid and natamycin grafting on LDPE. • The study investigated chemical and mechanical property changes by various times of UV light treatments. • Natamycin grafted film demonstrated antifungal function against mold and yeast. - Abstract: The purpose of this study was to develop an active non-migratory antifungal Low Density Polyethylene (LDPE) polymer for use in food packaged applications. The functional acrylic acid monomer was grafted on the LDPE film surface by photo-initiated graft polymerization using Ultra Violet light irradiation (from 0 to 5 min). Natamycin, an antifungal agent, was applied to the treated film to bind with the pendent functional groups and were evaluated its performance against mold and yeast. The grafted amounts were determined by gravimetric measurement and dye absorbance. Attenuated Total Reflectance/Fourier Transfer Infrared Spectroscopy, scanning electron microscopy, mechanical strength test was used to characterize film properties. The antifungal efficacy of the film was evaluated with Saccharomyces cerevisiae and Penicillium chrysogenum on growth media and fresh cut cantaloupe. The amounts of the grafted group were increased with the longer ultraviolet exposure time. The amount of the grafted natamycin on the treated film was up to 49.87 μg/cm{sup 2}, and the film inhibited mycelium formation of P. chrysogenum spores by over 60%. Due to the thickness of the film (less than 12.25 μm), long time UV exposure decrease the film’s mechanical strength. The application of such non-migratory active packaging film represents a promising approach to maintaining food quality with reduced additive.

  5. Polymer surface modification using UV treatment for attachment of natamycin and the potential applications for conventional food cling wrap (LDPE)

    International Nuclear Information System (INIS)

    Shin, Joongmin; Liu, Xiaojing; Chikthimmah, Naveen; Lee, Youn Suk

    2016-01-01

    Highlights: • The study suggests an optimized method for UV-induced antimicrobial agents grafting on LDPE. • The study evaluated the effective of various solvents for acrylic acid and natamycin grafting on LDPE. • The study investigated chemical and mechanical property changes by various times of UV light treatments. • Natamycin grafted film demonstrated antifungal function against mold and yeast. - Abstract: The purpose of this study was to develop an active non-migratory antifungal Low Density Polyethylene (LDPE) polymer for use in food packaged applications. The functional acrylic acid monomer was grafted on the LDPE film surface by photo-initiated graft polymerization using Ultra Violet light irradiation (from 0 to 5 min). Natamycin, an antifungal agent, was applied to the treated film to bind with the pendent functional groups and were evaluated its performance against mold and yeast. The grafted amounts were determined by gravimetric measurement and dye absorbance. Attenuated Total Reflectance/Fourier Transfer Infrared Spectroscopy, scanning electron microscopy, mechanical strength test was used to characterize film properties. The antifungal efficacy of the film was evaluated with Saccharomyces cerevisiae and Penicillium chrysogenum on growth media and fresh cut cantaloupe. The amounts of the grafted group were increased with the longer ultraviolet exposure time. The amount of the grafted natamycin on the treated film was up to 49.87 μg/cm"2, and the film inhibited mycelium formation of P. chrysogenum spores by over 60%. Due to the thickness of the film (less than 12.25 μm), long time UV exposure decrease the film’s mechanical strength. The application of such non-migratory active packaging film represents a promising approach to maintaining food quality with reduced additive.

  6. A novel method to prepare superhydrophobic, UV resistance and anti-corrosion steel surface

    KAUST Repository

    Isimjan, Tayirjan T.; Wang, Taoye; Rohani, Sohrab M F

    2012-01-01

    . The resulting surfaces were modified by the low free energy chemical PTES (1H,1H,2H,2H-Perfluorodecyltriethoxysilane). The experimental results of wettability exhibit that such modified surfaces have a strong repulsive force to water droplets, their static

  7. Transmittance enhancement of sapphires with antireflective subwavelength grating patterned UV polymer surface structures by soft lithography.

    Science.gov (United States)

    Lee, Soo Hyun; Leem, Jung Woo; Yu, Jae Su

    2013-12-02

    We report the total and diffuse transmission enhancement of sapphires with the ultraviolet curable SU8 polymer surface structures consisting of conical subwavelength gratings (SWGs) at one- and both-side surfaces for different periods. The SWGs patterns on the silicon templates were transferred into the SU8 polymer film surface on sapphires by a simple and cost-effective soft lithography technique. For the fabricated samples, the surface morphologies, wetting behaviors, and optical characteristics were investigated. For theoretical optical analysis, a rigorous coupled-wave analysis method was used. At a period of 350 nm, the sample with SWGs on SU8 film/sapphire exhibited a hydrophobic surface and higher total transmittance compared to the bare sapphire over a wide wavelength of 450-1000 nm. As the period of SWGs was increased, the low total transmittance region of < 85% was shifted towards the longer wavelengths and became broader while the diffuse transmittance was increased (i.e., larger haze ratio). For the samples with SWGs at both-side surfaces, the total and diffuse transmittance spectra were further enhanced compared to the samples with SWGs at one-side surface. The theoretical optical calculation results showed a similar trend to the experimentally measured data.

  8. UV laser ablation of silicon carbide ring surfaces for mechanical seal applications

    Science.gov (United States)

    Daurelio, Giuseppe; Bellosi, Alida; Sciti, Diletta; Chita, Giuseppe; Allegretti, Didio; Guerrini, Fausto

    2000-02-01

    Silicon carbide ceramic seal rings are treated by KrF excimer laser irradiation. Surface characteristics, induced by laser treatment, depend upon laser fluence, the number of laser pulses, their energy and frequency, the rotation rate of the ring and the processing atmosphere. It was ascertained that silicon carbide has to be processed under an inert atmosphere to avoid surface oxidation. Microstructural analyses of surface and cross section of the laser processed samples showed that the SiC surface is covered by a scale due to the melting/resolidification processes. At high fluence there are no continuous scales on the surfaces; materials is removed by decomposition/vaporization and the ablation depth is linearly dependent on the number of pulses. Different surface morphologies are observed. The evolution of surface morphology and roughness is discussed with reference to compositions, microstructure and physical and optical properties of the ceramic material and to laser processing parameters. Preliminary results on tribological behavior of the treated seals are reported.

  9. An oxygen-insensitive degradable resist for fabricating metallic patterns on highly curved surfaces by UV-nanoimprint lithography.

    Science.gov (United States)

    Hu, Xin; Huang, Shisong; Gu, Ronghua; Yuan, Changsheng; Ge, Haixiong; Chen, Yanfeng

    2014-10-01

    In this paper, an oxygen-insensitive degradable resist for UV-nanoimprint is designed, com-prising a polycyclic degradable acrylate monomer, 2,10-diacryloyloxymethyl-1,4,9,12-tetraoxa-spiro [4.2.4.2] tetradecane (DAMTT), and a multifunctional thiol monomer pentaerythritol tetra(3-mercaptopropionate) (PETMP). The resist can be quickly UV-cured in the air atmosphere and achieve a high monomer conversion of over 98%, which greatly reduce the adhesion force between the resist and the soft mold. High conversion, in company with an adequate Young's modulus (about 1 GPa) and an extremely low shrinkage (1.34%), promises high nanoimprint resolution of sub-50 nm. The cross-linked resist is able to break into linear molecules in a hot acid solvent. As a result, metallic patterns are fabricated on highly curved surfaces via the lift off process without the assistance of a thermoplastic polymer layer. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Physicochemical modifications accompanying UV laser induced surface structures on poly(ethylene terephthalate) and their effect on adhesion of mesenchymal cells.

    Science.gov (United States)

    Rebollar, Esther; Pérez, Susana; Hernández, Margarita; Domingo, Concepción; Martín, Margarita; Ezquerra, Tiberio A; García-Ruiz, Josefa P; Castillejo, Marta

    2014-09-07

    This work reports on the formation of different types of structures on the surface of polymer films upon UV laser irradiation. Poly(ethylene terephthalate) was irradiated with nanosecond UV pulses at 193 and 266 nm. The polarization of the laser beam and the irradiation angle of incidence were varied, giving rise to laser induced surface structures with different shapes and periodicities. The irradiated surfaces were topographically characterized by atomic force microscopy and the chemical modifications induced by laser irradiation were inspected via micro-Raman and fluorescence spectroscopies. Contact angle measurements were performed with different liquids, and the results evaluated in terms of surface free energy components. Finally, in order to test the influence of surface properties for a potential application, the modified surfaces were used for mesenchymal stem cell culture assays and the effect of nanostructure and surface chemistry on cell adhesion was evaluated.

  11. UV-C 13-50 ultraviolet irradiation unit for surface sterilization

    International Nuclear Information System (INIS)

    Bachmann, R.

    1979-01-01

    Brown Boveri have developed new watertight ultraviolet irradiation units for surface sterilization. Their main application is in packing techniques in the foodstuffs and pharmaceutical industries. This article describes the construction, germicidal effect, and applications of these irradiation units. (Auth.)

  12. Studies on cationic UV curing of cycloaliphatic diepoxide - epoxidised palm oil (EPO) for surface coatings

    International Nuclear Information System (INIS)

    Mek Zah Salleh; Mohd Hilmi Mahmood; Wan Rosli Wan Daud; Kumar, R.N.

    1999-01-01

    In recent years, there are growing trends in using vegetables oil as raw materials in resin production. Development of new products from palm oil derivatives such as epoxidised palm oil (EPO) is of particular interest to this country. The compatibility of EPO with cycloaliphatic diepoxide allows the development of a wide range of radiation curable formulations by cationic photoinitiators. Curing was done by means of a 20 cm wide IST UV, machine with the conditions of 7.5A current and 4 m/min conveyor speed. Sulphonium and ferrocenium salts were used as the cationic photoinitiators. A study was formulated to compromise the investigation of various effects on the cured film properties. These effects include; types and concentration of photoinitiators, formulating ratios, reactive diluents, photosensitizers and postcuring conditions. The effects on the gel fraction, pendulum hardness, tensile strength and elongation at break were investigated. The results showed that 30% of EPO was the maximum value that can be used in the formulation. It was also found that triarylsulphonium hexafluorophosphate has a very low solubility in EPO

  13. UV sensitivity of planktonic net community production in ocean surface waters

    Science.gov (United States)

    Regaudie-de-Gioux, Aurore; Agustí, Susana; Duarte, Carlos M.

    2014-05-01

    The net plankton community metabolism of oceanic surface waters is particularly important as it more directly affects the partial pressure of CO2 in surface waters and thus the air-sea fluxes of CO2. Plankton communities in surface waters are exposed to high irradiance that includes significant ultraviolet blue (UVB, 280-315 nm) radiation. UVB radiation affects both photosynthetic and respiration rates, increase plankton mortality rates, and other metabolic and chemical processes. Here we test the sensitivity of net community production (NCP) to UVB of planktonic communities in surface waters across contrasting regions of the ocean. We observed here that UVB radiation affects net plankton community production at the ocean surface, imposing a shift in NCP by, on average, 50% relative to the values measured when excluding partly UVB. Our results show that under full solar radiation, the metabolic balance shows the prevalence of net heterotrophic community production. The demonstration of an important effect of UVB radiation on NCP in surface waters presented here is of particular relevance in relation to the increased UVB radiation derived from the erosion of the stratospheric ozone layer. Our results encourage design future research to further our understanding of UVB effects on the metabolic balance of plankton communities.

  14. UV Direct Laser Interference Patterning of polyurethane substrates as tool for tuning its surface wettability

    Energy Technology Data Exchange (ETDEWEB)

    Estevam-Alves, Regina [Instituto de Física de São Carlos, Universidade de São Paulo, 13560-970 São Carlos (Brazil); Günther, Denise; Dani, Sophie; Eckhardt, Sebastian; Roch, Teja [Fraunhofer Institute for Material and Beam Technology IWS, Winterbergstr. 28, Dresden 01277 (Germany); Chair for Large Area Laser Based Surface Micro/Nano-Structuring, Institute for Manufacturing Technology, Technische Universität Dresden, George-Bähr-Str. 3c, 01069 Dresden (Germany); Mendonca, Cleber R., E-mail: crmendon@ifsc.usp.br [Instituto de Física de São Carlos, Universidade de São Paulo, 13560-970 São Carlos (Brazil); Cestari, Ismar N. [Heart Institute (InCOr), University of São Paulo Medical School, São Paulo 05403-000 (Brazil); Lasagni, Andrés F., E-mail: andres_fabian.lasagni@tu-dresden.de [Fraunhofer Institute for Material and Beam Technology IWS, Winterbergstr. 28, Dresden 01277 (Germany); Chair for Large Area Laser Based Surface Micro/Nano-Structuring, Institute for Manufacturing Technology, Technische Universität Dresden, George-Bähr-Str. 3c, 01069 Dresden (Germany)

    2016-06-30

    Highlights: • First reported experiments on Direct Laser Interference Patterning of polyurethane. • First reported sub-micrometer structures (feature size ∼250 nm) fabricated in polyurethane materials using laser processing technologies. • Anisotropic wetting behavior of structured surfaces and possibility to tune the contact angle as function of surface structure parameters. - Abstract: Direct Laser Interference Patterning (DLIP) is a versatile tool for the fabrication of micro and sub-micropatterns on different materials. In this work, DLIP was used to produce periodic surface structures on polyurethane (PU) substrates with spatial periods ranging from 0.5 to 5.0 μm. The influence of the laser energy density on the quality and topographical characteristics of the produced micropatterns was investigated. To characterize the surface topography of the produced structures, Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM) and Confocal Microscopy (CFM) were utilized. It was found that high quality and defect free periodic line-like patterns with spatial periods down to 500 nm could be fabricated, with structure depths between 0.88 up to 1.25 μm for spatial periods larger than 2.0 μm and up to 270 nm for spatial periods between 500 nm and 1.0 μm. Measurements of the contact angle of water on the treated surface allowed to identify an anisotropic wetting behavior depending mainly on the spatial period and filling factor of the structured surfaces.

  15. Low-level laser therapy: Effects on human face aged skin and cell viability of HeLa cells exposed to UV radiation

    Directory of Open Access Journals (Sweden)

    Mezghani Sana

    2015-01-01

    Full Text Available Chronic and excessive exposure to UV radiation leads to photoaging and photocarcinogenesis. Adequate protection of the skin against the deleterious effects of UV irradiation is essential. Low-level laser therapy (LLLT is a light source in the red to near-infrared range that has been accepted in a variety of medical applications. In this study, we explored the effect of LLLT in human face aged skin and the cell viability of HeLa cells exposed to UV radiation. We found that LLLT significantly reduced visible wrinkles and the loss of firmness of facial skin in aging subjects. Additionally, treatment of cultured HeLa cells with LLLT prior to or post UVA or UVB exposure significantly protected cells from UV-mediated cell death. All results showed the beneficial effects of LLLT on relieving signs of skin aging and its prevention and protection of the cell viability against UV-induced damage.

  16. UV and IR laser radiation's interaction with metal film and teflon surfaces

    Science.gov (United States)

    Fedenev, A. V.; Alekseev, S. B.; Goncharenko, I. M.; Koval', N. N.; Lipatov, E. I.; Orlovskii, V. M.; Shulepov, M. A.; Tarasenko, V. F.

    2003-04-01

    The interaction of Xe ([lambda] [similar] 1.73 [mu]m) and XeCl (0.308 [mu]m) laser radiation with surfaces of metal and TiN-ceramic coatings on glass and steel substrates has been studied. Correlation between parameters of surface erosion versus laser-specific energy was investigated. Monitoring of laser-induced erosion on smooth polished surfaces was performed using optical microscopy. The correlation has been revealed between characteristic zones of thin coatings damaged by irradiation and energy distribution over the laser beam cross section allowing evaluation of defects and adhesion of coatings. The interaction of pulsed periodical CO2 ([lambda] [similar] 10.6 [mu]m), and Xe ([lambda] [similar] 1.73 [mu]m) laser radiation with surfaces of teflon (polytetrafluoroethylene—PTFE) has been studied. Monitoring of erosion track on surfaces was performed through optical microscopy. It has been shown that at pulsed periodical CO2-radiation interaction with teflon the sputtering of polymer with formation of submicron-size particles occurs. Dependencies of particle sizes, form, and sputtering velocity on laser pulse duration and target temperature have been obtained.

  17. SO2 frost - UV-visible reflectivity and Io surface coverage

    Science.gov (United States)

    Nash, D. B.; Fanale, F. P.; Nelson, R. M.

    1980-01-01

    The reflectance spectrum in the range 0.24-0.85 microns of SO2 frost is measured in light of the discovery of SO2 gas in the atmosphere of Io and the possible discovery of the frost on its surface. Frost deposits up to 1.5 mm thick were grown in vacuum at 130 K and bi-directional reflectance spectra were obtained. Typical SO2 frost is found to exhibit very low reflectivity (2-5%) at 0.30 microns, rising steeply at 0.32 microns to attain a maximum reflectivity (75-80%) at 4.0 microns and uniformly high reflectivity throughout the visible and near infrared. Comparison with the full disk spectrum of Io reveals that no more than 20% of the surface can be covered with optically thick SO2 frost. Combinations of surface materials including SO2 frost which can produce the observed spectrum are indicated.

  18. Concentrations of the UV filter ethylhexyl methoxycinnamate in the aquatic compartment: a comparison of modelled concentrations for Swiss surface waters with empirical monitoring data.

    Science.gov (United States)

    Straub, Jürg Oliver

    2002-05-10

    UV filters in sunscreens and cosmetics protect the skin from damage through UV radiation. Many tonnes per year of UV filters are being used in Europe and will be present, at least seasonally, in detectable concentrations in surface waters similar to common pharmaceutically active substances. Predicted environmental concentrations (PECs) of ethylhexyl methoxycinnamate (EHMC; CAS 5466-77-3) were extrapolated for Switzerland, taking into consideration substance-specific environmental fate data and marketing estimates, by crude worst-case reckoning and by applying two environmental models (Mackay Level III; USES 3.0), both configured for Swiss hydrological and area data. By worst-case reckoning the summer PEC is 70.8-81.3 ng/l while for the remaining 8 months of the year the PEC is 13.1-15.1 ng/l. The Level III model results in concentrations of 2.4 ng/l during the summer and 0.44 ng/l during the rest of the year, while the USES 3.0 model gives an average PEC for the whole year of 7.6 ng/l. Pooling summer monitoring data (90 single analyses) from the River Rhine below Basel in the year 1997 (Water Protection Board of Basel) and from Lakes Zurich and Hüttner in 1998 (Poiger et al., in preparation) allowed a derivation of a probabilistic median concentration of 4.6 ng/l, a 95th-percentile concentration of 18.6 ng/l and a 99th-percentile concentration of 33.5 ng/l. The 6-fold range from the median value to the maximum calls for caution in interpreting published monitoring concentrations. Comparison of modelled PECs with realistic median concentrations shows that crude reckoning overestimates actual concentrations by a factor of about 10, probably through insufficient consideration of (further) degradation of EHMC in sewage works, surface waters, sediments or river banks. Both computer models, in contrast, are within the same order of magnitude as the actual summer concentrations. Based on the available data, both these environmental fate and distribution models give

  19. Influence of the surface structure on the filtration performance of UV-modified PES membranes

    DEFF Research Database (Denmark)

    Kæselev, Bozena Alicja; Kingshott, P.; Jonsson, Gunnar Eigil

    2002-01-01

    chemically characterised using X-ray photoelectron spectroscopy (XPS) and time of flight-static secondary ion mass spectrometry (TOF-static SIMS). The filtration performance of irradiated/non-modified and irradiated/modified membranes was examined in a crossflow cell, using a dextran solution. The filtration...... in relation to dextran when compared to membranes modified by AAG and AAP. This work suggests that the structure of the presence of grafted chains seems to be responsible for the observed changes to filtration performance of the modified membrane. Surface analysis supports the claim that the specific surface...

  20. Plant responses to UV-B irradiation are modified by UV-A irradiation

    International Nuclear Information System (INIS)

    Middleton, E.M.; Teramura, A.H.

    1993-01-01

    The increasing UV-B radiation (0.28-0.32 μm) reaching the earth's surface is an important concern. Plant response in artificial UV-B irradiation studies has been difficult to assess, especially regarding photosynthetic pigments, because the fluorescent lamps also produce UV-A (0.32-0.40μm) radiation which is involved with blue light in pigment synthesis. Both UV-A and UV-B irradiances were controlled in two glasshouse experiments conducted under relatively high PPFD (> 1300μmol m -2 s -1 ) at two biologically effective daily UV-B irradiances (10.7 and 14.1 kJ m -2 ); UV-A irradiances were matched in Controls (∼5, 9 kJ m -2 ). Normal, chlorophyll-deficient, and flavonoid-deficient isolines of soybean cultivar, Clark, were utilized. Many growth/ pigment variables exhibited a statistically significant interaction between light quality and quantity: in general, UV-A radiation moderated the damaging effects of UV-B radiation. Regression analyses demonstrated that a single negative function related photosynthetic efficiency to carotenoid Content (r 2 =0.73, P≤0.001), implying a open-quotes costclose quotes in maintaining carotenoids for photoprotection. A stomatal limitation to photosynthesis was verified and carotenoid content was correlated with UV-B absorbing compound levels, in UV-B irradiated plants

  1. Solar UV Irradiation-Induced Production of Greenhouse Gases from Plant Surfaces: From Leaf to Earth

    DEFF Research Database (Denmark)

    Mikkelsen, Teis Nørgaard; Bruhn, Dan; Ambus, Per

    2016-01-01

    -methane volatile organic compounds (NMVOC), NOx and N2O. This gas production, near or at the plant surface, is a new discovery and is normally not included in emission budgets (e.g. by the Intergovernmental Panel on Climate Change, IPCC) due to a lack of information with respect to validation and upscaling. For CH...

  2. Direct measurement of colloidal interactions between polyaniline surfaces in a uv-curable coating formulation

    DEFF Research Database (Denmark)

    Jafarzadeh, Shadi; Claesson, Per M.; Pan, Jinshan

    2014-01-01

    cantilever and a pressed pellet of either hydrophilic or hydrophobic polyaniline powders, in resins of various polymer:monomer ratios. A short-range purely repulsive interaction was observed between hydrophilic polyaniline (doped with phosphoric acid) surfaces in polyester acrylate resin. In contrast...

  3. Ultraviolet radiation exposure from UV-transilluminators.

    Science.gov (United States)

    Akbar-Khanzadeh, Farhang; Jahangir-Blourchian, Mahdi

    2005-10-01

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

  4. NANOSCALE STRUCTURES GENERATION WITHIN THE SURFACE LAYER OF METALS WITH SHORT UV LASER PULSES

    Directory of Open Access Journals (Sweden)

    Dmitry S. Ivanov

    2017-01-01

    Full Text Available We have completed modeling of a laser pulse influence on a gold target. We have applied a hybrid atomistic-continuum model to analyze the physical mechanisms responsible for the process of nanostructuring. The model combines the advantages of Molecular Dynamics and Two Temperature Model. We have carried out a direct comparison of the modeling results and experimental data on nano-modification due to a single ps laser pulse at the energy densities significantly exceeding the melting threshold. The experimental data is obtained due to a laser pulse irradiation at the wavelength of 248 nm and duration of 1.6 ps. The mask projection (diffraction grating creates the sinusoidal intensity distribution on a gold surface with periods of 270 nm, 350 nm, and 500 nm. The experimental data and modeling results have demonstrated a good match subject to complex interrelations between a fast material response to the laser excitation, generation of crystal defects, phase transitions and hydrodynamic motion of matter under condition of strong laser-induced non-equilibrium. The performed work confirms the proposed approach as a powerful tool for revealing the physical mechanisms underlying the process of nanostructuring of metal surfaces. Detailed understanding of the dynamics of these processes gives the possibility for designing the topology of functional surfaces on nano- and micro-scales.

  5. Selective Area Modification of Silicon Surface Wettability by Pulsed UV Laser Irradiation in Liquid Environment.

    Science.gov (United States)

    Liu, Neng; Moumanis, Khalid; Dubowski, Jan J

    2015-11-09

    The wettability of silicon (Si) is one of the important parameters in the technology of surface functionalization of this material and fabrication of biosensing devices. We report on a protocol of using KrF and ArF lasers irradiating Si (001) samples immersed in a liquid environment with low number of pulses and operating at moderately low pulse fluences to induce Si wettability modification. Wafers immersed for up to 4 hr in a 0.01% H2O2/H2O solution did not show measurable change in their initial contact angle (CA) ~75°. However, the 500-pulse KrF and ArF lasers irradiation of such wafers in a microchamber filled with 0.01% H2O2/H2O solution at 250 and 65 mJ/cm(2), respectively, has decreased the CA to near 15°, indicating the formation of a superhydrophilic surface. The formation of OH-terminated Si (001), with no measurable change of the wafer's surface morphology, has been confirmed by X-ray photoelectron spectroscopy and atomic force microscopy measurements. The selective area irradiated samples were then immersed in a biotin-conjugated fluorescein-stained nanospheres solution for 2 hr, resulting in a successful immobilization of the nanospheres in the non-irradiated area. This illustrates the potential of the method for selective area biofunctionalization and fabrication of advanced Si-based biosensing architectures. We also describe a similar protocol of irradiation of wafers immersed in methanol (CH3OH) using ArF laser operating at pulse fluence of 65 mJ/cm(2) and in situ formation of a strongly hydrophobic surface of Si (001) with the CA of 103°. The XPS results indicate ArF laser induced formation of Si-(OCH3)x compounds responsible for the observed hydrophobicity. However, no such compounds were found by XPS on the Si surface irradiated by KrF laser in methanol, demonstrating the inability of the KrF laser to photodissociate methanol and create -OCH3 radicals.

  6. Induction of ploidy level increments in an asporogenous industrial strain of the yeast Saccaromyces cerevisiae by UV irradiation

    International Nuclear Information System (INIS)

    Sasaki, Takashi

    1992-01-01

    Cells of an asporogenous industrial strain of the yeast Saccaromyces cerevisiae were irradiated with UV light by using a method that was developed previously. This treatment gave rise to large-cell clones among the surviving cells, from which colonies consisting of cells with a normal morphology and a prototropic property were obtained. The large-cell trait of these was stably inheritable, with the cell volumes being about twice that of the parent for 7 years on a slant agar medium at 4C with repeated transfers. The cellular DNA content of these clones, in comparison to those of two authentic haploid strains, was determined by chemical analysis. The ratio of the DNA contents showed that the parent and its large-cell derivatives were a diploid and tetraploids, respectively. No abnormality was found in the chromosomal DNA patterns of the large-cell clones, at least as determined by agarose gel electrophoresis with a CHEF-DR II pulsed-field electrophoresis system. These findings led to the conclusion that the UV light method is applicable for inducing ploidy level increments in the widely used yeast species S. cerevisiae

  7. Nicotinamide adenosine dinucleotide level in dimethylsulfate-treated or UV-irradiated mouse epidermis

    International Nuclear Information System (INIS)

    Balard, B.; Giacomoni, P.U.

    1989-01-01

    The level of nicotinamide (NAD) has been determined in the epidermis of 30 mice. Its value is 0.63+-0.15 μg/mg protein. Upon treatment with dimethylsulfate (DMS), the level of NAD drops in a dosedependent fashion. This diminution is reversible when low doses of DMS are used. Upon irradiation with ultraviolet light, the level of NAD drops in the irradiated epidermis, the treshold of saturation being below 1200 J/m 2 . There is also a drop in the level of NAD in the epidermis protected against irradiation with a black rubber sheet. (author). 17 refs.; 6 figs.; 1 tab

  8. Enabling HST UV Exploration of the Low Surface Brightness Universe: A Pilot Study with the WFC3 X Filter Set

    Science.gov (United States)

    Thilker, David

    2017-08-01

    We request 17 orbits to conduct a pilot study to examine the effectiveness of the WFC3/UVIS F300X filter for studying fundamental problems in star formation in the low density regime. In principle, the broader bandpass and higher throughput of F300X can halve the required observing time relative to F275W, the filter of choice for studying young stellar populations in nearby galaxies. Together with F475W and F600LP, this X filter set may be as effective as standard UVIS broadband filters for characterizing the physical properties of such populations. We will observe 5 low surface brightness targets with a range of properties to test potential issues with F300X: the red tail to 4000A and a red leak beyond, ghosts, and the wider bandpass. Masses and ages of massive stars, young star clusters, and clumps derived from photometry from the X filter set will be compared with corresponding measurements from standard filters. Beyond testing, our program will provide the first sample spanning a range of LSB galaxy properties for which HST UV imaging will be obtained, and a glimpse into the ensemble properties of the quanta of star formation in these strange environments. The increased observing efficiency would make more tractable programs which require several tens to hundreds of orbits to aggregate sufficient numbers of massive stars, young star clusters, and clumps to build statistical samples. We are hopeful that our pilot observations will broadly enable high-resolution UV imaging exploration of the low density frontier of star formation while HST is still in good health.

  9. UV and gamma irradiation effects on surface properties of polyurethane derivative from castor oil

    International Nuclear Information System (INIS)

    Azevedo, Elaine C.; Nascimento, Eduardo M.; Chierice, Gilberto O.; Claro Neto, Salvador

    2013-01-01

    Gamma and ultraviolet radiation effects on hardness, elastic modulus and viscoelastic properties of polyurethane derived from castor oil (PU) were investigated by nanoindentation tests. Modifications on surface morphology, induce by radiation, were observed by atomic force microscopy. The polyurethane derivative from castor oil shows good resistance to gamma radiation, with only small changes in hardness, elastic modulus, viscoelastic properties and contact angle. The hardness of PY increases at the near surface region due to UVA radiation and decreases after UVC radiation. The contact angle for water drop decreases after UVC radiation, by not after gamma radiation, despite a significant increase in roughness. Such results are attributed to different responses from polyurethane to radiation energy. Increase in hardness due to UVA is attributed to a higher crosslinking at shallow depths, while a decrease in mechanical properties may be attributed to chain scission. These results are consistent with the modifications on viscoelastic properties. Shore D hardness did not show the same trend as observed by nanoindentation results. Hardness, viscoelastic properties and contact angle of castor oil polyurethane are more severely influenced by UVC radiation, while gamma radiation does not have a significant effect. (author)

  10. UV and gamma irradiation effects on surface properties of polyurethane derivative from castor oil

    Energy Technology Data Exchange (ETDEWEB)

    Azevedo, Elaine C.; Nascimento, Eduardo M., E-mail: helunica@yahoo.com.br [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil); Chierice, Gilberto O.; Claro Neto, Salvador [Universidade de Sao Paulo (IQSC/USP), Sao Carlos, SP (Brazil). Instituto de Quimica; Lepienski, Carlos M. [Universidade Federal do Parana (UFPR), Curitiba (Brazil)

    2013-07-01

    Gamma and ultraviolet radiation effects on hardness, elastic modulus and viscoelastic properties of polyurethane derived from castor oil (PU) were investigated by nanoindentation tests. Modifications on surface morphology, induce by radiation, were observed by atomic force microscopy. The polyurethane derivative from castor oil shows good resistance to gamma radiation, with only small changes in hardness, elastic modulus, viscoelastic properties and contact angle. The hardness of PY increases at the near surface region due to UVA radiation and decreases after UVC radiation. The contact angle for water drop decreases after UVC radiation, by not after gamma radiation, despite a significant increase in roughness. Such results are attributed to different responses from polyurethane to radiation energy. Increase in hardness due to UVA is attributed to a higher crosslinking at shallow depths, while a decrease in mechanical properties may be attributed to chain scission. These results are consistent with the modifications on viscoelastic properties. Shore D hardness did not show the same trend as observed by nanoindentation results. Hardness, viscoelastic properties and contact angle of castor oil polyurethane are more severely influenced by UVC radiation, while gamma radiation does not have a significant effect. (author)

  11. Photoemission studies of clean and adsorbate covered metal surfaces using synchrotron and uv radiation sources

    International Nuclear Information System (INIS)

    Apai, G.R. II.

    1977-09-01

    Photoemission energy distribution experiments on clean metal and adsorbate-covered surfaces were performed under ultrahigh vacuum conditions by using x-ray and ultraviolet photon sources in the laboratory as well as continuously-tunable, highly polarized synchrotron radiation obtainable at the Stanford Synchrotron Radiation Laboratory (SSRL). Studies focused on two general areas: cross-section modulation in the photoemission process was studied as a function of photon energy and orbital composition. Sharp decreases in intensity of the valence bands of several transition metals (i.e., Ag, Au, and Pt) are attributed to the radial nodes in the respective wave functions. Adsorbate photoemission studies of CO adsorbed on platinum single crystals have demonstrated a very high spectral sensitivity to the 4sigma and (1π + 5sigma) peaks of CO at photon energies of 150 eV. Angle-resolved photoemission allowed determination of the orientation of CO chemisorbed on a Pt (111) or Ni(111) surface. Prelinimary results at high photon energies (approximately 150 eV) indicated scattering from the substrate which could yield chemisorption site geometries

  12. Influence of slight microstructural gradients on the surface properties of Ti6Al4V irradiated by UV

    International Nuclear Information System (INIS)

    Gallardo-Moreno, A.M.; Multigner, M.; Pacha-Olivenza, M.A.; Lieblich, M.; Jimenez, J.A.; Gonzalez-Carrasco, J.L.; Gonzalez-Martin, M.L.

    2009-01-01

    Ti6Al4V alloy is one of the most widely used materials for biomedical implants. Among its properties, it is remarkable the photoactivity displayed by its passive layer, which is mainly composed by titanium dioxide. However, variations in the processing conditions may yield to differences in the microstructure which can be reflected on the surface properties of the machined product. From contact angle measurements taken on different zones of samples removed from a commercial bar of Ti6Al4V, it has been shown that the modifications of the surface Gibbs energy suffered by the alloy under UV irradiation have a radial dependence. This behaviour is related to slight microstructural changes of the alloy, particularly with an increase in the volume fraction of the β-phase when moving to the interior of the sample, which alters the composition and/or microstructure of the passive layer along its radius. This study shows that gradients in the microstructure and physical properties are sample size dependent and are likely related to thermal gradients during processing.

  13. Effect of nontronite smectite clay on the chemical evolution of several organic molecules under simulated Mars surface UV radiation conditions

    Science.gov (United States)

    Poch, Olivier; Dequaire, Tristan; Stalport, Fabien; Jaber, Maguy; Lambert, Jean-François; Szopa, Cyril; Coll, Patrice

    2015-04-01

    The search for organic carbon-containing molecules at the surface of Mars, as clues of past habitability or remnants of life, is a major scientific goal for Mars exploration. Several lines of evidence, including the detection of phyllosilicates, suggest that early Mars offered favorable conditions for long-term sustaining of water. As a consequence, we can assume that in those days, endogenous chemical processes, or even primitive life, may have produced organic matter on Mars. Moreover, exogenous delivery from small bodies or dust particles is likely to have brought fresh organic molecules to the surface of Mars up today. Organic matter is therefore expected to be present at the surface/subsurface of the planet. But the current environmental conditions at the surface - UV radiation, oxidants and energetic particles - generate physico-chemical processes that may affect organic molecules. On the other hand, on Earth, phyllosilicates are known to accumulate and preserve organic matter. But are phyllosilicates efficient at preserving organic molecules under the current environmental conditions at the surface of Mars? We have monitored the qualitative and quantitative evolutions of glycine, urea and adenine interacting with the Fe3+-smectite clay nontronite, one of the most abundant phyllosilicates present at the surface of Mars, under simulated Martian surface ultraviolet light (190-400 nm), mean temperature (218 ± 2 K) and pressure (6 ± 1 mbar) in a laboratory simulation setup. We have tested organic-rich samples which may be representative of the evaporation of a warm little pond of liquid water having concentrated organics on Mars. For each molecule, we have observed how the nontronite influences the quantum efficiency of its photodecomposition and the nature of its solid evolution products. The results reveal a pronounced photoprotective effect of nontronite on the evolution of glycine and adenine: their efficiencies of photodecomposition are reduced by a factor

  14. Adhesion of nitrile rubber to UV-assisted surface chemical modified PET fabric, part II: Interfacial characterization of MDI grafted PET

    Energy Technology Data Exchange (ETDEWEB)

    Razavizadeh, Mahmoud; Jamshidi, Masoud, E-mail: mjamshidi@iust.ac.ir

    2016-08-30

    Highlights: • In this research UV-irradiated PET fabric was chemically modified. • The fabric at first carboxylated under UV irradiation using glutaric anhydride, then it was grafted using isocyanate (i.e. MDI). • The surface of the fabric was characterized before and after each treating satge. • The composite samples were prepared and tested for T-Peel test. The surfaces of the fabrics were surface characterized to understand. - Abstract: Fiber to rubber adhesion is an important subject in rubber industry. It is well known that surface treatment (i.e. physical, mechanical and chemical) is an effective method to improve interfacial bonding of fibers and/or fabrics to rubbers. UV irradiation is an effective method which has been used to increase fabric-rubber interfacial interactions. In this research UV assisted chemical modification of PET fabrics was used to increase PET to nitrile rubber (NBR) adhesion. Nitrile rubber is a perfect selection as fuel and oil resistant rubber. However it has weak bonding to PET fabric. For this purpose PET fabric was carboxylated under UV irradiation and then methylenediphenyl diisocyanate (MDI) was grafted on carboxylated PET. The chemical composition of the fabric before and after surface treatment was investigated by X-ray photoelectron spectroscopy (XPS). The sectional morphology of the experimental PET fibers and the interface between rubber compound and PET fabric was studied using scanning electron microscope (SEM). The morphology and structure of the product were analyzed by an energy dispersive X-ray spectrometer (EDX). FTIR-ATR and H NMR analysis were used to assess surface modifications on the PET irradiated fabrics.

  15. Adhesion of nitrile rubber to UV-assisted surface chemical modified PET fabric, part II: Interfacial characterization of MDI grafted PET

    International Nuclear Information System (INIS)

    Razavizadeh, Mahmoud; Jamshidi, Masoud

    2016-01-01

    Highlights: • In this research UV-irradiated PET fabric was chemically modified. • The fabric at first carboxylated under UV irradiation using glutaric anhydride, then it was grafted using isocyanate (i.e. MDI). • The surface of the fabric was characterized before and after each treating satge. • The composite samples were prepared and tested for T-Peel test. The surfaces of the fabrics were surface characterized to understand. - Abstract: Fiber to rubber adhesion is an important subject in rubber industry. It is well known that surface treatment (i.e. physical, mechanical and chemical) is an effective method to improve interfacial bonding of fibers and/or fabrics to rubbers. UV irradiation is an effective method which has been used to increase fabric-rubber interfacial interactions. In this research UV assisted chemical modification of PET fabrics was used to increase PET to nitrile rubber (NBR) adhesion. Nitrile rubber is a perfect selection as fuel and oil resistant rubber. However it has weak bonding to PET fabric. For this purpose PET fabric was carboxylated under UV irradiation and then methylenediphenyl diisocyanate (MDI) was grafted on carboxylated PET. The chemical composition of the fabric before and after surface treatment was investigated by X-ray photoelectron spectroscopy (XPS). The sectional morphology of the experimental PET fibers and the interface between rubber compound and PET fabric was studied using scanning electron microscope (SEM). The morphology and structure of the product were analyzed by an energy dispersive X-ray spectrometer (EDX). FTIR-ATR and H NMR analysis were used to assess surface modifications on the PET irradiated fabrics.

  16. Long-term structural canopy changes sustain net photosynthesis per ground area in high arctic Vaccinium uliginosum exposed to changes in near-ambient UV-B levels.

    Science.gov (United States)

    Boesgaard, Kristine S; Albert, Kristian R; Ro-Poulsen, Helge; Michelsen, Anders; Mikkelsen, Teis N; Schmidt, Niels M

    2012-08-01

    Full recovery of the ozone layer is not expected for several decades and consequently, the incoming level of solar ultraviolet-B (UV-B) will only slowly be reduced. Therefore to investigate the structural and photosynthetic responses to changes in solar UV-B we conducted a 5-year UV-B exclusion study in high arctic Greenland. During the growing season, the gas exchange (H₂O and CO₂) and chlorophyll-a fluorescence were measured in Vaccinium uliginosum. The leaf dry weight, carbon, nitrogen, stable carbon isotope ratio, chlorophyll and carotenoid content were determined from a late season harvest. The net photosynthesis per leaf area was on average 22% higher in 61% reduced UV-B treatment across the season, but per ground area photosynthesis was unchanged. The leaf level increase in photosynthesis was accompanied by increased leaf nitrogen, higher stomatal conductance and F(v)/F(m). There was no change in total leaf biomass, but reduction in total leaf area caused a pronounced reduction of specific leaf area and leaf area index in reduced UV-B. This demonstrates the structural changes to counterbalance the reduced plant carbon uptake seen per leaf area in ambient UV-B as the resulting plant carbon uptake per ground area was not affected. Thus, our understanding of long-term responses to UV-B reduction must take into account both leaf level processes as well as structural changes to understand the apparent robustness of plant carbon uptake per ground area. In this perspective, V. uliginosum seems able to adjust plant carbon uptake to the present amount of solar UV-B radiation in the High Arctic. Copyright © Physiologia Plantarum 2011.

  17. A Level Set Discontinuous Galerkin Method for Free Surface Flows

    DEFF Research Database (Denmark)

    Grooss, Jesper; Hesthaven, Jan

    2006-01-01

    We present a discontinuous Galerkin method on a fully unstructured grid for the modeling of unsteady incompressible fluid flows with free surfaces. The surface is modeled by embedding and represented by a levelset. We discuss the discretization of the flow equations and the level set equation...

  18. Evaluation of the levels of phthalate ester plasticizers in surface ...

    African Journals Online (AJOL)

    Evaluation of the levels of phthalate ester plasticizers in surface water of Ethiope ... Gas chromatography (GC) coupled with mass spectrometer (MS) was used to ... with their common use in plastic materials and other industrial chemicals.

  19. Uniform and pitting corrosion events induced by SCN- anions on Al alloys surfaces and the effect of UV light

    International Nuclear Information System (INIS)

    Amin, Mohammed A.

    2011-01-01

    The influence of the alloying elements on the uniform and pitting corrosion processes of Al-6061, Al-4.5%Cu, Al-7.5%Cu, Al-6%Si and Al-12%Si alloys was studied in 0.50 M KSCN solution at 25 o C. Open-circuit potential, Tafel polarization, linear polarization resistance (LPR) and ICP-AES measurements were used to study the uniform corrosion process on the surfaces of the tested alloys. Cyclic polarization, potentiostatic current-time transients and impedance techniques were employed for pitting corrosion studies. Obtained results were compared with pure Al. Passivation kinetics of the tested Al samples were also studied as a function of applied potential, [SCN - ] and sample composition by means of potentiostatic current transients. The induction time, after which the growth of stable pits occurs, decreased with increasing applied potential and [SCN - ]. Regarding to uniform corrosion, alloyed Cu was found to enhance the corrosion rate, while alloyed Si suppressed it. Alloying elements of the tested samples diminished pitting attack to an extent depending on the percentage of the alloying element in the sample. Among the investigated materials, Al-Si alloys exhibited the highest corrosion resistance towards uniform and pitting corrosion processes in KSCN solutions. The passive and dissolution behaviour of Al was also studied under the conditions of continuous illumination (300-450 nm) based on cyclic polarization and potentiostatic techniques. The incident photons had a little influence on pit initiation and a marked effect on pit growth. These explained in terms of a photo-induced modification of the passive film formed on the anode surface, which render it more resistant to pitting. The effects of UV photons energy and period of illumination on the morphology of the pitted surfaces were also studied.

  20. Determination of Trace Level Triclosan in Water by Online Preconcentration and HPLC-UV Diode Array

    Science.gov (United States)

    An online high performance liquid chromatography (HPLC) method for the detection and quantification of trace levels of triclosan in water is discussed. Triclosan, an anti-bacterial agent, and related compounds have been shown to reach municipal waste waters through the disposal ...

  1. Characteristics of UV-MicroO3 Reactor and Its Application to Microcystins Degradation during Surface Water Treatment

    Directory of Open Access Journals (Sweden)

    Guangcan Zhu

    2015-01-01

    Full Text Available The UV-ozone (UV-O3 process is not widely applied in wastewater and potable water treatment partly for the relatively high cost since complicated UV radiation and ozone generating systems are utilized. The UV-microozone (UV-microO3, a new advanced process that can solve the abovementioned problems, was introduced in this study. The effects of air flux, air pressure, and air humidity on generation and concentration of O3 in UV-microO3 reactor were investigated. The utilization of this UV-microO3 reactor in microcystins (MCs degradation was also carried out. Experimental results indicated that the optimum air flux in the reactor equipped with 37 mm diameter quartz tube was determined to be 18∼25 L/h for efficient O3 generation. The air pressure and humidity in UV-microO3 reactor should be low enough in order to get optimum O3 output. Moreover, microcystin-RR, YR, and LR (MC-RR, MC-YR, and MC-LR could be degraded effectively by UV-microO3 process. The degradation of different MCs was characterized by first-order reaction kinetics. The pseudofirst-order kinetic constants for MC-RR, MC-YR, and MC-LR degradation were 0.0093, 0.0215, and 0.0286 min−1, respectively. Glucose had no influence on MC degradation through UV-microO3. The UV-microO3 process is hence recommended as a suitable advanced treatment method for dissolved MCs degradation.

  2. UV-C irradiation disrupts platelet surface disulfide bonds and activates the platelet integrin alphaIIbbeta3

    NARCIS (Netherlands)

    Verhaar, Robin; Dekkers, David W. C.; de Cuyper, Iris M.; Ginsberg, Mark H.; de Korte, Dirk; Verhoeven, Arthur J.

    2008-01-01

    UV-C irradiation has been shown to be effective for pathogen reduction in platelet concentrates, but preliminary work indicated that UV-C irradiation of platelets can induce platelet aggregation. In this study, the mechanism underlying this phenomenon was investigated. Irradiation of platelets with

  3. Investigation on the photocatalytic degradation of pyrene on soil surfaces using nanometer anatase TiO2 under UV irradiation

    International Nuclear Information System (INIS)

    Dong Dianbo; Li Peijun; Li Xiaojun; Zhao Qing; Zhang Yinqiu; Jia Chunyun; Li Peng

    2010-01-01

    Photocatalytic degradation of pyrene on soil surfaces was investigated in the presence of nanometer anatase TiO 2 under a variety of conditions. After being spiked with pyrene, soil samples loaded with different amounts of TiO 2 (0%, 1%, 2%, 3%, and 4%, w/w) were exposed to UV irradiation for 25 h. The results indicated that the photocatalytic degradation of pyrene followed pseudo-first-order kinetics. TiO 2 accelerated the degradation of pyrene generally as indicated by the half-life reduction from 45.90 to 31.36 h, corresponding to the TiO 2 amounts from 0% to 4%, respectively. The effects of H 2 O 2 , light intensity and humic acids on the degradation of pyrene were also investigated. The degradation of pyrene increased along with increasing the concentration of H 2 O 2 , light intensity and the concentration of humic acids. All results indicated that the photocatalytic method in the presence of nanometer anatase TiO 2 was an advisable choice for the treatments of PAHs polluted soil in the future.

  4. Polymer surface modification using UV treatment for attachment of natamycin and the potential applications for conventional food cling wrap (LDPE)

    Science.gov (United States)

    Shin, Joongmin; Liu, Xiaojing; Chikthimmah, Naveen; Lee, Youn Suk

    2016-11-01

    The purpose of this study was to develop an active non-migratory antifungal Low Density Polyethylene (LDPE) polymer for use in food packaged applications. The functional acrylic acid monomer was grafted on the LDPE film surface by photo-initiated graft polymerization using Ultra Violet light irradiation (from 0 to 5 min). Natamycin, an antifungal agent, was applied to the treated film to bind with the pendent functional groups and were evaluated its performance against mold and yeast. The grafted amounts were determined by gravimetric measurement and dye absorbance. Attenuated Total Reflectance/Fourier Transfer Infrared Spectroscopy, scanning electron microscopy, mechanical strength test was used to characterize film properties. The antifungal efficacy of the film was evaluated with Saccharomyces cerevisiae and Penicillium chrysogenum on growth media and fresh cut cantaloupe. The amounts of the grafted group were increased with the longer ultraviolet exposure time. The amount of the grafted natamycin on the treated film was up to 49.87 μg/cm2, and the film inhibited mycelium formation of P. chrysogenum spores by over 60%. Due to the thickness of the film (less than 12.25 μm), long time UV exposure decrease the film's mechanical strength. The application of such non-migratory active packaging film represents a promising approach to maintaining food quality with reduced additive.

  5. Study on the surface chemical properties of UV excimer laser irradiated polyamide by XPS, ToF-SIMS and CFM

    International Nuclear Information System (INIS)

    Yip, Joanne; Chan, Kwong; Sin, Kwan Moon; Lau, Kai Shui

    2002-01-01

    Polyamide (nylon 6) was irradiated by a pulsed ultraviolet (UV) excimer laser with a fluence below its ablation threshold. Chemical modifications on laser treated nylon were studied by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (Tof-SIMS) and chemical force microscopy (CFM). XPS study provides information about changes in chemical composition and the chemical-state of atom types on the fiber surface. The high sensitivity of ToF-SIMS to the topmost layers was used to detect crosslinking after the laser treatment. Gold-coated AFM tips modified with -COOH terminated self-assembled alkanethiol monolayers (SAMs) were used to measure adhesion forces on the untreated and laser treated samples. XPS results revealed that the irradiated samples have higher oxygen content than prior to laser irradiation. Tof-SIMS analysis illustrated that carbonyl groups in nylon 6 decrease significantly but hydroxyl groups increase after low-fluence laser irradiation. The adhesion force measurements by CFM showed spatial distribution of hydroxyl groups on nylon 6 after the laser treatment

  6. UV-protection of Natural and Synthetic Fabrics by Surface Treatment under the effect of Gamma Irradiation

    International Nuclear Information System (INIS)

    El-Naggar, AW.M.; Zohdy, M.H.; Ali, N.M.

    2008-01-01

    Synthetic and natural fabrics were surface coated with gamma radiation curable novel formulations. These formulations were based on naturally occurring Alum individually and in binary mixture with ZnO beside different functional oligomers and monomers. The physical properties of the treated fabrics were evaluated in terms of ultraviolet protection, moisture regain, and water absorption. Also, the effect of coating formulations on the crystallinity was investigated by X-ray diffraction (XRD). The results of ultraviolet protection factor (UPF) showed that the formulation containing 30% of Alum caused a significant UPF values (50+) according to standard rating over untreated fabrics. When ZnO was incorporated in the formulation, the UPF factor was increased by two folds. A decrease in the moisture regain and water absorption of fabrics was featured with ZnO, however, in case of Alum a decrease followed by an increase was observed. In conclusion, these novel coats could be taken as an nontoxic alternative UV-resist finishing agents for fabrics

  7. UV/PAR radiations and DOM properties in surface coastal waters of the Canadian shelf of the Beaufort Sea during summer 2009

    Science.gov (United States)

    Para, J.; Charrière, B.; Matsuoka, A.; Miller, W. L.; Rontani, J. F.; Sempéré, R.

    2012-11-01

    Water masses from the Beaufort Sea in the Arctic Ocean were evaluated for dissolved organic carbon (DOC), and optical characteristics including UV and PAR diffuse attenuation (Kd), and chromophoric and fluorescent dissolved organic matter (CDOM and FDOM) as part of the MALINA field campaign (30 July to 27 August). Even with relatively low mean daily solar radiation incident on the sea surface (0.12 ± 0.03, 8.46 ± 1.64 and 18.09 ± 4.20 kJ m-2 for UV-B (305 nm), UV-A (380 nm) and PAR, respectively), we report significant light penetration with 10% irradiance depths (Z10% (λ)) reaching 9.5 m for 340 nm (UV-A) radiation in the Eastern sector and 4.5 m in the Mackenzie River influenced area (Western sector). Spectral absorption coefficients (aCDOM (350 nm) (m-1)) were significantly correlated to both diffuse attenuation coefficients (Kd) in the UV-A and UV-B and to DOC concentrations. This indicates CDOM as the dominant attenuator of UV solar radiation and suggests its use as an optical proxy for DOC concentrations in this region. Extrapolating CDOM to DOC relationships, we estimate that ~ 16% of the DOC in the Mackenzie River does not absorb radiation at 350 nm. DOC and CDOM discharges by the Mackenzie River during the MALINA Cruise are estimated as ~ 0.22 TgC and 0.18 TgC, respectively. Three dissolved fluorescent components (C1-C3) were identified by fluorescence Excitation/Emission Matrix Spectroscopy (EEMS) and PARAFAC analysis. Our results showed an in-situ biological component (C1) that co-dominated with a terrestrial humic-like component (C2) in the Mackenzie Delta sector, whereas the protein-like (C3) component dominated in the saltiest waters of the North East sector.

  8. Similarities in the induction of synthesis of a cell-surface polypeptide in Arthrobacter sp. by near-UV irradiation and photodynamic conditions

    International Nuclear Information System (INIS)

    Hoober, J.K.; Franzi, J.

    1983-01-01

    Irradiation of aerobic suspensions of Arthrobacter sp. with near-UV light (310-400 nm) induced synthesis of a 21 000 dalton, cell-surface polypeptide. Synthesis of this polypeptide also was induced by visible light in the presence of photodynamic dyes. Induction of the polypeptide in ear-UV light and with visible light plus dyes was inhibited by histidine. Hemin inhibited induction in near-UV light and in visible light with methylene blue, neutral red and acriflavin, which are cationic dyes, but failed to inhibit induction in visible light with rose bengal, an anionic dye. These results suggested that inhibition by hemin required electrostatically favored interaction between the anionic porphyrin and the sensitizer, and that the near-UV light effect was mediated by a cationic or neutral endogenous sensitizer. The similarities in the responses of the cells to near-UV irradiation and visible light plus dyes suggested that the mechanism of induction under the two conditions was the same. (author)

  9. Solar UV-B effects on PSII performance in Betula nana are influenced by PAR level and reduced by EDU

    DEFF Research Database (Denmark)

    Albert, Kristian Rost; Mikkelsen, Teis Nørgaard; Ro-Poulsen, Helge

    2012-01-01

    -B transparent filter control (Teflon), UV-B-absorbing filter (Mylar) and UV-AB-absorbing filter (Lexan). Ethylenediurea (EDU), a chemical normally used to protect plants against ozone injury, was sprayed on the leaves both in the field and in an additional laboratory study to investigate if EDU mitigated...

  10. Synthesis and properties of a novel UV-cured fluorinated siloxane graft copolymer for improved surface, dielectric and tribological properties of epoxy acrylate coating

    International Nuclear Information System (INIS)

    Yan, Zhenlong; Liu, Weiqu; Gao, Nan; Wang, Honglei; Su, Kui

    2013-01-01

    A novel functional fluorinated siloxane graft copolymer bearing with vinyl end-groups was synthesized from dihydroxypropyl-terminated poly(dimethylsiloxane) (PDMS), dicarboxyl terminated poly(2,2,3,4,4,4-hexafluorobutyl acrylate) oligomer (CTHFA), 2,4-toluene diissocyanate (TDI) and 2-hydroxyethyl methacrylate (HEMA). The chemical structure was characterized by FT-IR and GPC. The effect of concentration of the vinyl-capped fluorosilicone graft copolymer (Vi-PFSi) on the surface, thermal properties, dielectric and tribological properties of UV-cured films was investigated. Contact angles and surface energies showed that the high hydrophobic and oleophobic surfaces were obtained by incorporation of Vi-PFSi at very low amount (0.5 wt%). X-ray photoelectron spectroscopy (XPS) evidenced that the fluorinated and siloxane moiety selectively migrated to the outermost surface of UV-cured film, thus reduced its surface energy from 45.42 to 15.40 mN/m 2 without affecting its bulk properties. The morphology of fracture surface of modified film exhibited rough fracture surface only at the outermost surface, revealing fluorinated and siloxane groups migrated toward air-side surface. The dielectric constants decreased from 5.32 (1 MHz) for bisphenol-A epoxy methacrylate (EMA) to 2.82 (1 MHz) for modified film when the Vi-PFSi copolymer concentration increased from 0 to 0.8 wt%. Tribological results from abrasion tester suggested that the Vi-PFSi could obviously reduce the abrasion weight loss of modified films.

  11. Effects of UV radiation on freshwater metazooplankton

    International Nuclear Information System (INIS)

    Tartarotti, B.

    1999-06-01

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

  12. Surface core-level shifts for simple metals

    DEFF Research Database (Denmark)

    Aldén, Magnus; Skriver, Hans Lomholt; Johansson, Börje

    1994-01-01

    screening, whereby a SCLS becomes equivalent to the surface segregation energy of a core-ionized atom, a quantity we obtain by separate bulk and surface impurity calculations. The results are in good agreement with experiment in most of those cases where the data originates from single-crystal measurements....... We discuss the surface shifts of the electrostatic potentials and the band centers in order to trace the microscopic origin of the SCLS in the simple metals and find that the anomalous subsurface core-level shifts in beryllium are caused by charge dipoles, which persist several layers into the bulk...

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

    Science.gov (United States)

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

    2017-07-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-07-10

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

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

    International Nuclear Information System (INIS)

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

    2017-01-01

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

  16. In situ deposition of graphene nanosheets on wood surface by one-pot hydrothermal method for enhanced UV-resistant ability

    International Nuclear Information System (INIS)

    Wan, Caichao; Jiao, Yue; Li, Jian

    2015-01-01

    Graphical abstract: - Highlights: • The graphene/wood nanocomposites were fabricated via a mild fast one-pot hydrothermal method. • Graphene nanosheets were in situ deposited on the surface of the wood matrix. • The incorporation of graphene nanosheets results in the improvement in the thermal stability of the graphene/wood. • The graphene/wood exhibits superior UV resistance performance. - Abstract: Graphene nanosheets were successfully in situ deposited on the surface of the wood matrix via a mild fast one-pot hydrothermal method, and the resulting hybrid graphene/wood (GW) were characterized by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Raman spectroscopy, and thermogravimetric analysis (TGA). According to the results, the wood matrix was evenly coated by dense uninterrupted multilayer graphene membrane structure, which was formed by layer-by-layer self-assembly of graphene nanosheets. Meanwhile, the graphene coating also induced significant improvement in the thermal stability of GW in comparison with that of the original wood (OW). Accelerated weathering tests were employed to measure and determine the UV-resistant ability of OW and GW. After about six hundred hours of experiments, the surface color change of GW was much less than that of OW; besides, the Fourier transform infrared spectroscopy (FTIR) analysis also proved the less significant changes in surface chemical compositions of GW. The results both indicated that the graphene coating effectively protected wood surface from UV damage. Therefore, this class of GW composite might be expected to be served as high-performance wooden building material for outdoor or some particular harsh environments like strong UV radiation regions use

  17. Ionic liquid-based single-drop microextraction followed by liquid chromatography-ultraviolet spectrophotometry detection to determine typical UV filters in surface water samples.

    Science.gov (United States)

    Vidal, Lorena; Chisvert, Alberto; Canals, Antonio; Salvador, Amparo

    2010-04-15

    A user-friendly and inexpensive ionic liquid-based single-drop microextraction (IL-SDME) procedure has been developed to preconcentrate trace amounts of six typical UV filters extensively used in cosmetic products (i.e., 2-hydroxy-4-methoxybenzophenone, isoamyl 4-methoxycinnamate, 3-(4'-methylbenzylidene)camphor, 2-ethylhexyl 2-cyano-3,3-diphenylacrylate, 2-ethylhexyl 4-dimethylaminobenzoate and 2-ethylhexyl 4-methoxycinnamate) from surface water samples prior to analysis by liquid chromatography-ultraviolet spectrophotometry detection (LC-UV). A two-stage multivariate optimization approach was developed by means of a Plackett-Burman design for screening and selecting the significant variables involved in the SDME procedure, which were later optimized by means of a circumscribed central composite design. The studied variables were drop volume, sample volume, agitation speed, ionic strength, extraction time and ethanol quantity. Owing to particularities, ionic liquid type and pH of the sample were optimized separately. Under optimized experimental conditions (i.e., 10 microL of 1-hexyl-3-methylimidazolium hexafluorophosphate, 20 mL of sample containing 1% (v/v) ethanol and NaCl free adjusted to pH 2, 37 min extraction time and 1300 rpm agitation speed) enrichment factors up to ca. 100-fold were obtained depending on the target analyte. The method gave good levels of repeatability with relative standard deviations varying between 2.8 and 8.8% (n=6). Limits of detection were found in the low microg L(-1) range, varying between 0.06 and 3.0 microg L(-1) depending on the target analyte. Recovery studies from different types of surface water samples collected during the winter period, which were analysed and confirmed free of all target analytes, ranged between 92 and 115%, showing that the matrix had a negligible effect upon extraction. Finally, the proposed method was applied to the analysis of different water samples (taken from two beaches, two swimming pools and a

  18. Low level chemiluminescence measurement of the binding of 8-methoxypsoralen to proteins and lymphocytic surfaces

    International Nuclear Information System (INIS)

    Lange, B.

    1980-01-01

    Photochemotherapy with 8-methoxypsoralen (8-MOP) and longwave ultraviolet light is beneficial in such different disorders like psoriasis, lichen planus, and mykosis fungoides. In contrast to a widely accepted hypothesis 8-MOP does not solely bind to nucleic acid, but also to certain proteins. The mechanism of this binding as well as the precise binding area are unknown. Therefore the UV-provoked reactions of 8-MOP with a lipid mixture, a glucosaminoglycan solution, a protein solution, and lymphocyte suspensions, respectively were investigated using low level chemiluminescence (LLCL). It was found an 8-MOP concentration-dependent decrease of LLCL intensity in the lymphocyte suspensions (10 3 to 10 4 cells/μl). This effect is result of the diminution of the photoactive 8-MOP content of the solution. 8-MOP binds quickly and in the course of a free radical reaction to lymphocytic surfaces and coincidentally loses its potency to start LLCL-detectable free radical chain responses. (author)

  19. Induction of wound-periderm-like tissue in Kalanchoe pinnata (Lam.) Pers. (Crassulaceae) leaves as a defence response to high UV-B radiation levels.

    Science.gov (United States)

    Nascimento, Luana Beatriz dos Santos; Moreira, Nattacha dos Santos; Leal-Costa, Marcos Vinícius; Costa, Sônia Soares; Tavares, Eliana Schwartz

    2015-10-01

    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. 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. 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. 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. © The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  20. Automatic Measurement of Low Level Contamination on Concrete Surfaces

    International Nuclear Information System (INIS)

    Tachibana, M.; Itoh, H.; Shimada, T.; Yanagihara, S.

    2002-01-01

    Automatic measurement of radioactivity is necessary for considering cost effectiveness in final radiological survey of building structures in decommissioning nuclear facilities. The RAPID (radiation measuring pilot device for surface contamination) was developed to be applied to automatic measurement of low level contamination on concrete surfaces. The RAPID has a capability to measure contamination with detection limit of 0.14 Bq/cm2 for 60Co in 30 seconds of measurement time and its efficiency is evaluated to be 5 m2/h in a normal measurement option. It was confirmed that low level contamination on concrete surfaces could be surveyed by the RAPID efficiently compared with direct measurement by workers through its actual application

  1. Immobilized enzymes: understanding enzyme - surface interactions at the molecular level.

    Science.gov (United States)

    Hoarau, Marie; Badieyan, Somayesadat; Marsh, E Neil G

    2017-11-22

    Enzymes immobilized on solid supports have important and industrial and medical applications. However, their uses are limited by the significant reductions in activity and stability that often accompany the immobilization process. Here we review recent advances in our understanding of the molecular level interactions between proteins and supporting surfaces that contribute to changes in stability and activity. This understanding has been facilitated by the application of various surface-sensitive spectroscopic techniques that allow the structure and orientation of enzymes at the solid/liquid interface to be probed, often with monolayer sensitivity. An appreciation of the molecular interactions between enzyme and surface support has allowed the surface chemistry and method of enzyme attachement to be fine-tuned such that activity and stability can be greatly enhanced. These advances suggest that a much wider variety of enzymes may eventually be amenable to immobilization as green catalysts.

  2. Origin of metallic surface core-level shifts

    DEFF Research Database (Denmark)

    Aldén, Magnus; Skriver, Hans Lomholt; Abrikosov, I. A.

    1995-01-01

    The unique property of the open 4f energy shell in the lanthanide metals is used to show that the initial-state energy shift gives an insufficient description of surface core-level shifts. Instead a treatment, which fully includes the final-state screening, account for the experimentally observed...

  3. Effects of UV-B radiation levels on concentrations of phytosterol, ergothioneine, and polyphenolic compounds in mushroom powder used as dietary supplements

    Science.gov (United States)

    Compositional changes of powder dietary supplement made from mushrooms previously exposed to different levels of UV-B irradiation were evaluated for the bioactive naturally occurring mushroom anti-oxidant, ergothioneine, other natural polyphenolic anti-oxidants: e.g. flavonoids, lignans, and others,...

  4. Variability in the level of UV induced DNA damage in lymphocytes from unexposed and exposed to pesticides donors from Hungary

    International Nuclear Information System (INIS)

    Cebulska-Wasilewska, A.; Dyga, W.; Krasnowolski, S.; Florjan, D.; Siffel, C.

    2000-01-01

    incubation due to high level of DNA damage measured before and immediately after UV exposure. Frozen probes with lymphocytes after thawing revealed a large number of cells with high damages. Such a high level of initial DNA damage and small number of analyzed lymphocytes made probably impossible finding any influence of pesticides neither on the level of DNA damage nor on variability in the individual repair capacities. In conclusion, our results have not shown any influence of occupational exposures to DNA damage level and cellular capacity to repair. (author)

  5. Development of radiation curable surface coating based on soybean oil. part II: Evaluation of the prepared acrylated resin as surface coatings by using EB or UV sources for radiation curing applications

    International Nuclear Information System (INIS)

    Ibrahim, M.S.; Said, H.M.; Moussa, I.M.

    2005-01-01

    In recent years, there has been a growing trend in using vegetable oils as raw materials in acylation production that can be cured by UV/EB systems. The acrylated resin formulates by using individually different functional acrylate monomers were prepared and cured by EB or UV sources. The characterization properties of the cured films were investigated in terms of pendulum hardness, bending, impact, gloss, adhesion and chemical tests. Other formulations were prepared by mixing a constant ratio of different functional acrylate monomers and exposed to UV or EB irradiation. The results showed that the hardness of cured films were increased by increasing the functionality of monomers with excellent adhesion for all formulations but at expense of other properties involving bending and impact tests. Therefore, it can be deduce that the hardness of the curing surface coating by using EB was found to be nearly twice the hardness of the curing surface coating by using UV irradiation. Also, the best formulations which have given good chemical and mechanical properties are (mono-di) functional acrylate monomer resin under EB and (mono-tri) functional acrylate monomer resin under UV irradiation

  6. Adhesion of nitrile rubber to UV-assisted surface chemical modified PET fabric, part II: Interfacial characterization of MDI grafted PET

    Science.gov (United States)

    Razavizadeh, Mahmoud; Jamshidi, Masoud

    2016-08-01

    Fiber to rubber adhesion is an important subject in rubber industry. It is well known that surface treatment (i.e. physical, mechanical and chemical) is an effective method to improve interfacial bonding of fibers and/or fabrics to rubbers. UV irradiation is an effective method which has been used to increase fabric-rubber interfacial interactions. In this research UV assisted chemical modification of PET fabrics was used to increase PET to nitrile rubber (NBR) adhesion. Nitrile rubber is a perfect selection as fuel and oil resistant rubber. However it has weak bonding to PET fabric. For this purpose PET fabric was carboxylated under UV irradiation and then methylenediphenyl diisocyanate (MDI) was grafted on carboxylated PET. The chemical composition of the fabric before and after surface treatment was investigated by X-ray photoelectron spectroscopy (XPS). The sectional morphology of the experimental PET fibers and the interface between rubber compound and PET fabric was studied using scanning electron microscope (SEM). The morphology and structure of the product were analyzed by an energy dispersive X-ray spectrometer (EDX). FTIR-ATR and H NMR analysis were used to assess surface modifications on the PET irradiated fabrics.

  7. Nonlinear (MARS modeling of long-term variations of surface UV-B radiation as revealed from the analysis of Belsk, Poland data for the period 1976–2000

    Directory of Open Access Journals (Sweden)

    J. W. Krzyścin

    Full Text Available A new, powerful statistical technique, multivariate adaptive regression splines (MARS, is applied to reproduce monthly fractional deviations of UV-B doses over Belsk, Poland, during the snowless (May–October part of the year in the period 1976–2000. Two kinds of regressors were used: local ones (total ozone, percentage of sky covered by low-, mid-, high-level clouds or total solar radiation over Belsk and non-local ones, i.e. those describing the long-distance forcings on the surface UV-B due to changes in the global atmospheric circulation. Standard indices of the Quasi-Biennial, North Atlantic, El Niño-Southern Oscillations, and the 11-year solar activity were used as non-local regressors. The results there indicate that the MARS procedure is able to reproduce the observed year-to-year and decadal oscillations in the UV data. The MARS model yields better model-observation agreement than an ordinary least-squares fit based on the same set of regressors. It is found that MARS is capable of handling interactions between the local and non-local regressors, suggesting a possible nonlinear nature of connections between variables characterizing the atmospheric transparency over Belsk and the long-distance forcings. MARS enables a reconstruction of the surface UV-B variations over any site based on the cloud and ozone data presently stored on web pages.

    Key words. Atmospheric composition and structure (aerosols and particles; biosphere-atmosphere interactions

  8. Solar UV irradiation-induced production of N2O from plant surfaces - low emissions rates but all over the world.

    Science.gov (United States)

    Mikkelsen, T. N.; Bruhn, D.; Ambus, P.

    2016-12-01

    Nitrous oxide (N2O) is an important long-lived greenhouse gas and precursor of stratospheric ozone depleting mono-nitrogen oxides. The atmospheric concentration of N2O is persistently increasing; however, large uncertainties are associated with the distinct source strengths. Here we investigate for the first time N2O emission from terrestrial vegetation in response to natural solar ultra violet radiation. We conducted field site measurements to investigate N2O atmosphere exchange from grass vegetation exposed to solar irradiance with and without UV-screening. Further laboratory tests were conducted with a range of species to study the controls and possible loci of UV-induced N2O emission from plants. Plants released N2O in response to natural sunlight at rates of c. 20-50 nmol m-2 h-1, mostly due to the UV component. The emission rate is temperature dependent with a rather high activation energy indicative for an abiotic process. The prevailing zone for the N2O formation appears to be at the very surface of leaves. However, only c. 26% of the UV-induced N2O appears to originate from plant-N. Further, the process is dependent on atmospheric oxygen concentration. Our work demonstrates that ecosystem emission of the important greenhouse gas, N2O, may be up to c. 30% higher than hitherto assumed.

  9. Effects of prenatal exposure to surface-coated nanosized titanium dioxide (UV-Titan). A study in mice

    DEFF Research Database (Denmark)

    Hougaard, Karin S.; Jackson, Petra; Jensen, Keld A.

    2010-01-01

    to a nanoparticulate UV-filter (UV-titan L181). Methods: Time-mated mice (C57BL/6BomTac) were exposed by inhalation 1h/day to 42 mg/m(3) aerosolized powder (1.7.10(6) n/cm(3); peak-size: 97 nm) on gestation days 8-18. Endpoints included: maternal lung inflammation; gestational and litter parameters; offspring...... the central zone of the open field and exposed female offspring displayed enhanced prepulse inhibition. Cognitive function was unaffected (Morris water maze test). Conclusion: Inhalation exposure to nano-sized UV Titan dusts induced long term lung inflammation in time-mated adult female mice. Gestationally...

  10. Maternal inhalation of surface-coated nanosized titanium dioxide (UV-Titan) in C57BL/6 mice

    DEFF Research Database (Denmark)

    Jackson, Petra; Halappanavar, Sabina; Hougaard, Karin Sorig

    2013-01-01

    We investigated effects of maternal pulmonary exposure to titanium dioxide (UV-Titan) on prenatally exposed offspring. Time-mated mice (C57BL/6BomTac) were inhalation exposed (1 h/day to 42 mg UV-Titan/m(3) aerosolised powder or filtered air) during gestation days (GDs) 8-18. We evaluated DNA...... strand breaks using the comet assay in bronchoalveolar lavage (BAL) cells and livers of the time-mated mice (5 and 26-27 days after inhalation exposure), and in livers of the offspring (post-natal days (PND) 2 and 22). We also analysed hepatic gene expression in newborns using DNA microarrays. UV-Titan...

  11. UV production of methane from surface and sedimenting IDPs on Mars in light of REMS data and with insights for TGO

    Science.gov (United States)

    Moores, John E.; Smith, Christina L.; Schuerger, Andrew C.

    2017-11-01

    This paper refines model predictions for the production of methane from UV-irradiated interplanetary dust particles (IDPs) now that the Rover Environmental Monitoring Station (REMS) instrument onboard the Mars Science Laboratory (MSL) Rover has made the first measurements of the UV environment on the surface of Mars, at Gale Crater. Once these measurements are included in a UV radiative transfer model, we find that modelled UV sol-integrated energies across the planet are lower than pre-measurement estimates by 35% on average, considering all latitudes and seasons. This reduction, in turn, reduces the predicted production of methane from individual accreting IDPs, extending their lifetimes and increasing the surface concentration of organics that must accumulate in order to emit sufficient methane to balance the accretion of organic compounds to Mars. Emission from reasonable accumulations of IDPs could range up to ∼7.9 × 10-4 ppbv sol-1. Richer deposits of organic carbon at the surface may emit methane at no more than 3.9 ppbv sol-1. An examination of IDP-derived methane production during atmospheric settling indicates that no more than 0.32% of organic carbon from meteor streams may be deposited in the atmosphere. Thus, such a process cannot explain either the spikes observed in methane nor the low equilibrium values observed by MSL. Instead, this discrepancy may be explained if geographical and vertical distribution will be an important input for models attempting to understand the results to be derived from the Trace Gas Orbiter (TGO) mission that will map methane concentrations in the martian atmosphere in 2018 at 0.01 ppbv.

  12. Semi-permeable surface analytical reversed-phase column for the improved trace analysis of acidic pesticides in water with coupled-column reversed-phase liquid chromatography with UV detection. Determination of bromoxynil and bentazone in surface water.

    Science.gov (United States)

    Hogendoorn, E A; Westhuis, K; Dijkman, E; Heusinkveld, H A; den Boer, A C; Evers, E A; Baumann, R A

    1999-10-08

    The coupled-column (LC-LC) configuration consisting of a 3 microm C18 column (50 x 4.6 mm I.D.) as the first column and a 5 microm C18 semi-permeable-surface (SPS) column (150 x 4.6 mm I.D.) as the second column appeared to be successful for the screening of acidic pesticides in surface water samples. In comparison to LC-LC employing two C18 columns, the combination of C18/SPS-C18 significantly decreased the baseline deviation caused by the hump of the co-extracted humic substances when using UV detection (217 nm). The developed LC-LC procedure allowed the simultaneous determination of the target analytes bentazone and bromoxynil in uncleaned extracts of surface water samples to a level of 0.05 microg/l in less than 15 min. In combination with a simple solid-phase extraction step (200 ml of water on a 500 mg C18-bonded silica) the analytical procedure provides a high sample throughput. During a period of about five months more than 200 ditch-water samples originating from agricultural locations were analyzed with the developed procedure. Validation of the method was performed by randomly analyzing recoveries of water samples spiked at levels of 0.1 microg/l (n=10), 0.5 microg/l (n=7) and 2.5 microg/l (n=4). Weighted regression of the recovery data showed that the method provides overall recoveries of 95 and 100% for bentazone and bromoxynil, respectively, with corresponding intra-laboratory reproducibilities of 10 and 11%, respectively. Confirmation of the analytes in part of the samples extracts was carried out with GC-negative ion chemical ionization MS involving a derivatization step with bis(trifluoromethyl)benzyl bromide. No false negatives or positives were observed.

  13. Genotoxicity testing of samples generated during UV/H2O2 treatment of surface water for the production of drinking water using the Ames test in vitro and the Comet assay and the SCE test in vivo

    NARCIS (Netherlands)

    Penders, E.J.M.; Martijn, A.J.; Spenkelink, A.; Alink, G.M.; Rietjens, I.; Hoogenboezem, W.

    2012-01-01

    UV/H2O2 treatment can be part of the process converting surface water to drinking water, but would pose a potential problem when resulting in genotoxicity. This study investigates the genotoxicity of samples collected from the water treatment plant Andijk, applying UV/H2O2 treatment with an

  14. Evaluation of hydrogen and oxygen impurity levels on silicon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kenny, M J; Wielunski, L S; Netterfield, R P; Martin, P J; Leistner, A [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Lindfield, NSW (Australia). Div. of Applied Physics

    1997-12-31

    This paper reports on surface analytical techniques used to quantify surface concentrations of impurities such as oxygen and hydrogen. The following analytical techniques were used: Rutherford and Backscattering, elastic recoil detection, time-of-flight SIMS, spectroscopic ellipsometry, x-ray photoelectron spectroscopy. The results have shown a spread in thickness of oxide layer, ranging from unmeasurable to 1.6 nm. The data must be considered as preliminary at this stage, but give some insight into the suitability of the techniques and a general idea of the significance of impurities at the monolayer level. These measurements have been carried out on a small number of silicon surfaces both semiconductor grade <111> crystalline material and silicon which has been used in sphere fabrication. 5 refs., 1 fig.

  15. Evaluation of hydrogen and oxygen impurity levels on silicon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kenny, M.J.; Wielunski, L.S.; Netterfield, R.P.; Martin, P.J.; Leistner, A. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Lindfield, NSW (Australia). Div. of Applied Physics

    1996-12-31

    This paper reports on surface analytical techniques used to quantify surface concentrations of impurities such as oxygen and hydrogen. The following analytical techniques were used: Rutherford and Backscattering, elastic recoil detection, time-of-flight SIMS, spectroscopic ellipsometry, x-ray photoelectron spectroscopy. The results have shown a spread in thickness of oxide layer, ranging from unmeasurable to 1.6 nm. The data must be considered as preliminary at this stage, but give some insight into the suitability of the techniques and a general idea of the significance of impurities at the monolayer level. These measurements have been carried out on a small number of silicon surfaces both semiconductor grade <111> crystalline material and silicon which has been used in sphere fabrication. 5 refs., 1 fig.

  16. "PROCESS and UVolution: photochemistry experiments in Low Earth Orbit": investigation of the photostability of organic and mineral material exposed to Mars surface UV radiation conditions

    Science.gov (United States)

    Stalport, Fabien; Guan, Yuan Yong; Noblet, Audrey; Coll, Patrice; Szopa, Cyril; Macari, Frederique; Person, Alain; Chaput, Didier; Raulin, Francois; Cottin, Hervé

    The harsh martian environment could explain the lack of organics and minerals such as car-bonates by destroying them: i) no organic molecule has been found at the two different landing sites of the Viking landers within the detection limits of the instruments onboard, ii) to date, no large deposits of carbonates have been detected and their detection is specific of local ar-eas and in very low amounts. In this context several experimental and numerical modelling studies were led to evaluate the possibility for the destruction or evolution of the organics and carbonates under the martian surface environmental conditions. The presence of UV radiation has been proposed to explain the photodecomposition of such material. This is the reason why, to investigate the nature, abundance, and stability of organic and mineral material that could survive under such environmental conditions, we exposed in low Earth orbit organic molecules and carbonates (also biominerals) with martian relevance to solar UV radiation ¿ 200 nm, in the frame of the experiment UVolution, onboard the BIOPAN ESA module which was set outside a Russian Foton automated capsule and exposed to space condition during 12 days in September 2007, and the experiment PROCESS (hervé peux tu rajouter quelques infos sur le temps exact d'exposition stp) which was set outside the International Space Station (ISS). Here, we present results with regard to the impact of solar UV radiation on the targeted molecules. Preliminary results indicate that that no organic sample seems to resist to the solar UV radiation if directly exposed to it. Conversely our results show that the exposed carbonates seem to be stable to the solar UV radiation if directly exposed to it. Moreover, the stability of the biominerals strengthens the interest to explore deeper their potential as life records at Mars. Hence they should be considered as primary targets for in situ analyses during future missions.

  17. Trace-level mercury removal from surface water

    International Nuclear Information System (INIS)

    Klasson, K.T.; Bostick, D.T.

    1998-01-01

    Many sorbents have been developed for the removal of mercury and heavy metals from waters; however, most of the data published thus far do not address the removal of mercury to the target levels represented in this project. The application to which these sorbents are targeted for use is the removal of mercury from microgram-per-liter levels to low nanogram-per-liter levels. Sorbents with thiouronium, thiol, amine, sulfur, and proprietary functional groups were selected for these studies. Mercury was successfully removed from surface water via adsorption onto Ionac SR-4 and Mersorb resins to levels below the target goal of 12 ng/L in batch studies. A thiol-based resin performed the best, indicating that over 200,000 volumes of water could be treated with one volume of resin. The cost of the resin is approximately $0.24 per 1,000 gal of water

  18. Sea level: measuring the bounding surfaces of the ocean

    Science.gov (United States)

    Tamisiea, Mark E.; Hughes, Chris W.; Williams, Simon D. P.; Bingley, Richard M.

    2014-01-01

    The practical need to understand sea level along the coasts, such as for safe navigation given the spatially variable tides, has resulted in tide gauge observations having the distinction of being some of the longest instrumental ocean records. Archives of these records, along with geological constraints, have allowed us to identify the century-scale rise in global sea level. Additional data sources, particularly satellite altimetry missions, have helped us to better identify the rates and causes of sea-level rise and the mechanisms leading to spatial variability in the observed rates. Analysis of all of the data reveals the need for long-term and stable observation systems to assess accurately the regional changes as well as to improve our ability to estimate future changes in sea level. While information from many scientific disciplines is needed to understand sea-level change, this review focuses on contributions from geodesy and the role of the ocean's bounding surfaces: the sea surface and the Earth's crust. PMID:25157196

  19. Sea level: measuring the bounding surfaces of the ocean.

    Science.gov (United States)

    Tamisiea, Mark E; Hughes, Chris W; Williams, Simon D P; Bingley, Richard M

    2014-09-28

    The practical need to understand sea level along the coasts, such as for safe navigation given the spatially variable tides, has resulted in tide gauge observations having the distinction of being some of the longest instrumental ocean records. Archives of these records, along with geological constraints, have allowed us to identify the century-scale rise in global sea level. Additional data sources, particularly satellite altimetry missions, have helped us to better identify the rates and causes of sea-level rise and the mechanisms leading to spatial variability in the observed rates. Analysis of all of the data reveals the need for long-term and stable observation systems to assess accurately the regional changes as well as to improve our ability to estimate future changes in sea level. While information from many scientific disciplines is needed to understand sea-level change, this review focuses on contributions from geodesy and the role of the ocean's bounding surfaces: the sea surface and the Earth's crust. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  20. Surface drainage in leveled land: Implication of slope

    Directory of Open Access Journals (Sweden)

    Antoniony S. Winkler

    Full Text Available ABSTRACT In the lowlands of Rio Grande do Sul, land leveling is mostly carried out with no slope for the purpose of rice production. In this environment, soils with a low hydraulic conductivity are predominant owing to the presence of a practically impermeable B-horizon near the surface. Land leveling leads to soil accommodation resulting in the formation of depressions where water accumulates after heavy rainfalls, subsequently leading to problems with crops implanted in succession to rice, such as soybeans. The objective of this research was to quantify the areas and volumes of water accumulation in soil as a function of the slope of land leveling. Five typical leveled lowland areas were studied as a part of this research. The original areas presented slopes of 0, 0.20, 0.25, 0.28 and 0.40%, which were used to generate new digital elevation models with slopes between 0 and 0.5%. These newly generated digital models were used to map the depressions with surface water storage. In conclusion, land leveling with slopes higher than 0.1% is recommended to minimize problems with superficial water storage in rice fields.

  1. Mechanism of the immobilization of surfactants on polymeric surfaces by means of an argon plasma treatment: Influence of UV radiation

    NARCIS (Netherlands)

    Lens, J.P.; Spaay, B.; Terlingen, J.G.A.; Engbers, G.H.M.; Feijen, Jan

    1999-01-01

    The mechanism of the immobilization of the surfactant sodium 10-undecenoate (C11(:)) on poly(ethylene) (PE) by means of an argon plasma treatment has been investigated. In particular, the influence of the vacuum ultraviolet (UV) radiation emitted by the argon plasma on the immobilization was

  2. Influence of fiber surface-treatment on interfacial property of poly(L-lactic acid)/ramie fabric biocomposites under UV-irradiation hydrothermal aging

    Energy Technology Data Exchange (ETDEWEB)

    Chen Dakai; Li Jing [Institute of Nano- and Bio-polymeric Materials, School of Material Science and Engineering, Tongji University, Shanghai 200092 (China); Ren Jie, E-mail: renjie6598@163.com [Institute of Nano- and Bio-polymeric Materials, School of Material Science and Engineering, Tongji University, Shanghai 200092 (China) and Key Laboratory of Advanced Civil Engineering Materials, Ministry of Education, Tongji University, Shanghai 200092 (China)

    2011-04-15

    Research highlights: {yields} Ramie fiber is used as reinforced material because it's lowest water absorption among sisal, jute, kenaf and ramie fiber. {yields} Fiber surface-treatment can cause an accelerated decline in mechanical properties of PLLA biocomposites after UV-irradiation hydrothermal aging. {yields} The swelling of ramie fibers reduce the interfacial adhesive strength in critical area of PLLA matrix-ramie fabric interface. - Abstract: The present study is devoted to the effect of fiber surface-treatment on the interfacial property of biocomposites based on poly(L-lactic acid) (PLLA) and ramie fabric. Ramie fiber is used as reinforced material because it's lowest water absorption among sisal, jute, kenaf and ramie fiber. Fiber surface-treatment can increase the water absorption of natural fibers. SEM images show that PLLA biocomposites with treated ramie fabric exhibit better interfacial adhesion character. DMA results show that the storage modulus of PLLA biocomposites with treated ramie increase compared to neat PLLA and PLLA biocomposites with untreated ramie. Unexpectedly, fiber surface-treatment can cause an accelerated decline in mechanical properties of PLLA biocomposites after UV-irradiation hydrothermal aging. Finally, GPC results show that there is no obvious decline in the molecular weight of PLLA. The main reason for this decline is the interfacial destructive effect induced by the water absorption of ramie fiber.

  3. Low salinity and high-level UV-B radiation reduce single-cell activity in antarctic sea ice bacteria.

    Science.gov (United States)

    Martin, Andrew; Hall, Julie; Ryan, Ken

    2009-12-01

    Experiments simulating the sea ice cycle were conducted by exposing microbes from Antarctic fast ice to saline and irradiance regimens associated with the freeze-thaw process. In contrast to hypersaline conditions (ice formation), the simulated release of bacteria into hyposaline seawater combined with rapid exposure to increased UV-B radiation significantly reduced metabolic activity.

  4. Use of reiterative primer extension methodology to map UV-induced photoproducts at the nucleotide level in the laci gene from genomic DNA

    International Nuclear Information System (INIS)

    Chandrasekhar, D.; Houten, B. Van

    1994-01-01

    A newly developed reiterative primer extension assay has been employed to examine photoproduct formation and repair at the nucleotide level. Analysis of UV-induced DNA photoproduct hotspots in the first 184 base pairs of the laci genes of genomic E. coli DNA has revealed that photoproducts are formed linearly with dose and display a sequence-dependent increase. Generally, pyrimdine dimers were twice as frequent as all other UV-induced photoproducts. However, specific sites showed differing distributions. A post-irradiation recovery period revealed differences in the repair efficiency at individual nucleotides. Repair of photoproducts on the transcribed strand was generally twice as efficient as repair of photoproducts on the nontranscribed strand, indicating that strand-specific DNA repair occurs in the constitutively transcribed laci gene of E. coli. The UV-induced DNA photoproduct distribution following repair was well correlated with an established UV-induced mutation spectrum for wild-type E. coli cells. This analysis revealed that photoproduct hotspots on the efficiently repaired transcribed strand did not correlate with mutagenic hotspots. These data strongly support the hypothesis that mutations arise at inefficiently repaired sites on the nontranscribed strand

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

    Science.gov (United States)

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

    2014-06-01

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

  6. Optimized surface-slab excited-state muffin-tin potential and surface core level shifts

    International Nuclear Information System (INIS)

    Rundgren, J.

    2003-01-01

    An optimized muffin-tin (MT) potential for surface slabs with preassigned surface core-level shifts (SCLS's) is presented. By using the MT radii as adjustable parameters the model is able to conserve the definition of the SCLS with respect to the bulk and concurrently to generate a potential that is continuous at the MT radii. The model is conceived for elastic electron scattering in a surface slab with exchange-correlation interaction described by the local density approximation. The model employs two data bases for the self-energy of the signal electron (after Hedin and Lundqvist or Sernelius). The potential model is discussed in detail with two surface structures Be(101-bar0), for which SCLS's are available, and Cu(111)p(2x2)Cs, in which the close-packed radii of the atoms are extremely different. It is considered plausible that tensor LEED based on an optimized MT potential can be used for determining SCLS's

  7. Ab initio surface core-level shifts and surface segregation energies

    DEFF Research Database (Denmark)

    Aldén, Magnus; Skriver, Hans Lomholt; Johansson, Börje

    1993-01-01

    We have calculated the surface core-level energy shifts of the 4d and 5d transition metals by means of local-density theory and a Green’s-function technique based on the linear muffin-tin orbitals method. Final-state effects are included by treating the core-ionized atom as an impurity located in...

  8. Global atmospheric change and herbivory: Effects of elevated levels of UV-B radiation, atmospheric CO2 and temperature on boreal woody plants and their herbivores

    International Nuclear Information System (INIS)

    Veteli, T.

    2003-01-01

    The aim of this study was to assess the effects of elevated ultraviolet-B radiation (UV-B, 280- 320 nm), atmospheric CO 2 , temperature and soil nitrogen level on the growth and chemical quality of boreal deciduous woody plants and on performance of the herbivorous insects feeding on them. Eggs and larvae of Operophtera brumata (L.) (Lepidoptera, Geometridae) were subjected to elevated UV-B radiation in the laboratory. Two willow species, Salix phylicifolia L. (Salicaceae) and S. myrsinifolia Salisb., were grown in an UV-B irradiation field where the responses of both plants and their herbivorous insects were monitored. S. myrsinifolia, Betula pendula Ehrh. (Betulaceae) and B. pubescens Roth. were subjected to elevated CO 2 and temperature and different fertilisation levels in closed-top climatic chambers. To assess the indirect effects of the different treatments, the leaves of experimental willows and birches were fed to larvae of Phratora vitellinae (L.) (Coleoptera, Chrysomelidae) and adults of Agellastica alni L. in the laboratory. Elevated UV-B radiation significantly decreased the survival and performance of eggs and larvae of O. brumata. It also increased concentrations of some flavonoids and phenolic acids in S. myrsinifolia and S. phylicifolia, while the low-UV-B- absorbing phenolics, e. g. condensed tannins, gallic acid derivatives and salicylates, either decreased or remained unaffected. Both the height growth and biomass of one S. phylicifolia clone was sensitive to elevated levels of UV-B radiation. Abundance of adults and larvae of a willow- feeding leaf beetle, P. vitellinae, was increased under elevated UV-B; but this did not lead to increased leaf damage on the host plants. There were no significant differences in performance of the larvae feeding on differentially treated willow leaves, but adult A. alni preferred UV-B-treated leaves to ambient control leaves. Elevated CO 2 and temperature significantly increased the height growth of S

  9. Effects of He{sup +} ion implantation on surface properties of UV-cured Bis-GMA/TEGDMA bio-compatible resins

    Energy Technology Data Exchange (ETDEWEB)

    Fuentes, G.G., E-mail: gfuentes@ain.e [Center of Advanced Surface Engineering, AIN, Cordovilla-Pamplona, E-31191 (Spain); Esparza, J.; Rodriguez, R.J. [Center of Advanced Surface Engineering, AIN, Cordovilla-Pamplona, E-31191 (Spain); Manso-Silvan, M. [Departamento de Fisica Aplicada, Universidad Autonoma de Madrid, Cantoblanco, E-28049 (Spain); Palomares, J. [Instituto de Ciencia de Materiales de Madrid, ICMM-CSIC, Cantoblanco, E-28049 (Spain); Juhasz, J.; Best, S. [Cambridge Centre for Medical Materials, Department of Materials Science and Metallurgy, University of Cambridge, Pembroke Str, Cambridge CB2 3QZ (United Kingdom); Mattilla, R.; Vallittu, P. [Institute of Dentistry, Turku Clinical Biomaterials Centre, Itaeinen Pitkaekatu 4, B FI-20520, Turku (Finland); Achanta, S. [Falex Tribology Wingepark 23 B, 3110 Rotselaar (Belgium); Giazzon, M.; Weder, G. [Centre Suisse d' Electronique et de Microtechnique, CSEM, Jaquet-Drot 1, CH-2002 Neuchatel (Switzerland); Donati, I. [Department of Life Sciences, University of Trieste, Via Licio Giorgieri 1, I 34127 Trieste (Italy)

    2011-01-15

    This work reports on the surface characterisation of 2,2-bis[4-(2-hydroxy-3-methacryloxyl-oxypropoxy)phenyl]propane/triethylene glycol dimethacrylate bio-compatible resins after high energy He{sup +} ion implantation treatments. The samples have been characterised by diffuse reflectance FT-IR, X-ray photo-electron spectroscopy, ultramicro-hardness and nano-scratch wear tests. In addition, osteblast cell assays MG-63 have been used to test the bio-compatibility of the resin surfaces after the ion implantation treatments. It has been observed that the maximum surface hardening of the resin surfaces is achieved at He-ion implantation energies of around 50 keV and fluences of 1 x 10{sup 16} cm{sup -2}. At 50 keV of He-ion bombardment, the wear rate of the resin surface decreases by a factor 2 with respect to the pristine resin. Finally, in vitro tests indicate that the He-ion implantation does not affect to the cell-proliferation behaviour of the UV-cured resins. The enhancement of the surface mechanical properties of these materials can have beneficial consequences, for instance in preventing wear and surface fatigue of bone-fixation prostheses, whose surfaces are continuously held to sliding and shearing contacts of sub-millimetre scale lengths.

  10. Influence of occupational exposure to pesticides on the level of DNA damage induced in human lymphocytes (Polish group) by UV-C and X-rays

    International Nuclear Information System (INIS)

    Dyga, W.; Drag, Z.; Cebulska-Wasilewska, A.

    2002-01-01

    The aim of this study was to find out whether occupational exposure to pesticides might affect the individual susceptibility of various donors to the induction of DNA damage by genotoxic agents (UV-C, X-rays) and the efficiency of cellular repair. Previously cryo preserved lymphocytes were defrosted, and DNA damage in the lymphocytes prior to any in vitro studies was investigated with the application of the Comet assay. In order to evaluate the susceptibilities of human lymphocytes to genotoxic agents and the variability of repair capacities, the DNA migrations were estimated immediately after exposure to UV-C light or X-rays and after two hours. On average, the DNA damage detected in untreated lymphocytes was significantly higher in the group exposed to pesticides than in reference group. UV-C treated lymphocytes from group exposed to pesticides shows a greater statistically significant level of DNA migration compared to the reference group, detected after 2 hours incubation in the absence of PHA. Significantly lower responses to X-rays and higher levels of residual DNA damage were detected in the lymphocytes of donors from the group exposed to pesticides compared with the reference group. In conclusion, our results suggest that occupational exposure to pesticides influences the level of induced DNA damage, and the cellular capabilities of repair. (author)

  11. Dynamics of gas-surface interactions atomic-level understanding of scattering processes at surfaces

    CERN Document Server

    Díez Muniño, Ricardo

    2013-01-01

    This book gives a representative survey of the state of the art of research on gas-surface interactions. It provides an overview of the current understanding of gas surface dynamics and, in particular, of the reactive and non-reactive processes of atoms and small molecules at surfaces. Leading scientists in the field, both from the theoretical and the experimental sides, write in this book about their most recent advances. Surface science grew as an interdisciplinary research area over the last decades, mostly because of new experimental technologies (ultra-high vacuum, for instance), as well as because of a novel paradigm, the ‘surface science’ approach. The book describes the second transformation which is now taking place pushed by the availability of powerful quantum-mechanical theoretical methods implemented numerically. In the book, experiment and theory progress hand in hand with an unprecedented degree of accuracy and control. The book presents how modern surface science targets the atomic-level u...

  12. UV/PAR radiation and DOM properties in surface coastal waters of the Canadian shelf of the Beaufort Sea during summer 2009

    Directory of Open Access Journals (Sweden)

    J. Para

    2013-04-01

    Full Text Available Surface waters from the Beaufort Sea in the Arctic Ocean were evaluated for dissolved organic carbon (DOC, and optical characteristics including UV (ultraviolet radiation and PAR (photosynthetically active radiation diffuse attenuation (Kd, and chromophoric and fluorescent dissolved organic matter (CDOM and FDOM as part of the MALINA field campaign (30 July to 27 August. Spectral absorption coefficients (aCDOM (350 nm (m−1 were significantly correlated to both diffuse attenuation coefficients (Kd in the UV-A and UV-B and to DOC concentrations. This indicates CDOM as the dominant attenuator of both UV and PAR solar radiation and suggests its use as an optical proxy for DOC concentrations in this region. While the Mackenzie input is the main driver of CDOM dynamics in low salinity waters, locally, primary production can create significant increases in CDOM. Extrapolating CDOM to DOC relationships, we estimate that ∼16% of the DOC in the Mackenzie River does not absorb radiation at 350 nm. The discharges of DOC and its chromophoric subset (CDOM by the Mackenzie River during the MALINA cruise are estimated as ∼0.22 TgC and 0.18 TgC, respectively. Three dissolved fluorescent components (C1–C3 were identified by fluorescence excitation/emission matrix spectroscopy (EEMS and parallel factor (PARAFAC analysis. Our results showed an aquatic dissolved organic matter (DOM component (C1, probably produced in the numerous lakes of the watershed, that co-dominated with a terrestrial humic-like component (C2 in the Mackenzie Delta Sector. This aquatic DOM could partially explain the high CDOM spectral slopes observed in the Beaufort Sea.

  13. UV/PAR radiation and DOM properties in surface coastal waters of the Canadian shelf of the Beaufort Sea during summer 2009

    Science.gov (United States)

    Para, J.; Charrière, B.; Matsuoka, A.; Miller, W. L.; Rontani, J. F.; Sempéré, R.

    2013-04-01

    Surface waters from the Beaufort Sea in the Arctic Ocean were evaluated for dissolved organic carbon (DOC), and optical characteristics including UV (ultraviolet) radiation and PAR (photosynthetically active radiation) diffuse attenuation (Kd), and chromophoric and fluorescent dissolved organic matter (CDOM and FDOM) as part of the MALINA field campaign (30 July to 27 August). Spectral absorption coefficients (aCDOM (350 nm) (m-1)) were significantly correlated to both diffuse attenuation coefficients (Kd) in the UV-A and UV-B and to DOC concentrations. This indicates CDOM as the dominant attenuator of both UV and PAR solar radiation and suggests its use as an optical proxy for DOC concentrations in this region. While the Mackenzie input is the main driver of CDOM dynamics in low salinity waters, locally, primary production can create significant increases in CDOM. Extrapolating CDOM to DOC relationships, we estimate that ∼16% of the DOC in the Mackenzie River does not absorb radiation at 350 nm. The discharges of DOC and its chromophoric subset (CDOM) by the Mackenzie River during the MALINA cruise are estimated as ∼0.22 TgC and 0.18 TgC, respectively. Three dissolved fluorescent components (C1-C3) were identified by fluorescence excitation/emission matrix spectroscopy (EEMS) and parallel factor (PARAFAC) analysis. Our results showed an aquatic dissolved organic matter (DOM) component (C1), probably produced in the numerous lakes of the watershed, that co-dominated with a terrestrial humic-like component (C2) in the Mackenzie Delta Sector. This aquatic DOM could partially explain the high CDOM spectral slopes observed in the Beaufort Sea.

  14. The Impact of UV-dose, Body Surface Area Exposed and Other Factors on Cutaneous Vitamin D Synthesis Measured as Serum 25(OH)D Concentration: Systematic Review and Meta-analysis.

    Science.gov (United States)

    Jager, Nadine; Schöpe, Jakob; Wagenpfeil, Stefan; Bocionek, Peter; Saternus, Roman; Vogt, Thomas; Reichrath, Jörg

    2018-02-01

    To optimize public health campaigns concerning UV exposure, it is important to characterize factors that influence UV-induced cutaneous vitamin D production. This systematic review and meta-analysis investigated the impact of different individual and environmental factors including exposed body surface area (BSA), UVB dose and vitamin D status, on serum 25(OH)D concentration. In accordance with Preferred Reporting Items for Systematic Reviews and Meta-analyses, and Meta-analysis of Observational studies in Epidemiology guidelines, a systematic literature search was conducted (MEDLINE; 01/1960-07/2016) investigating the impact of these factors on vitamin D status after artificial UV exposure as main outcome measure. Summary mean differences [and 95% confidence interval (CI)] were derived from random-effects meta-analysis to account for possible heterogeneity across studies. Meta-regression was conducted to account for impact of UVB dose, baseline 25(OH)D level and BSA. We identified 15 studies, with an estimated mean 25(OH)D rise per standard erythema dose (SED) of 0.19 nmol/l (95% CI 0.11-0.26 nmol/l). Results from meta-regression suggest a significant impact of UV dose and baseline 25(OH)D concentration on serum 25(OH)D level (p<0.01). Single UVB doses between 0.75 and 3 SED resulted in the highest rise of serum 25(OH)D per dose unit. BSA exposed had a smaller, non-proportional, not significant impact. Partial BSA exposure resulted in relatively higher rise compared to whole-body exposure (e.g. exposure of face and hands caused an 8-fold higher rise of serum 25(OH)D concentration/SED/1% BSA compared to whole-body exposure). Our findings support previous reports, estimating that the half-life of serum 25(OH)D varies depending on different factors. Our results indicate that partial BSA exposure (e.g. 10%) with moderate UV doses (e.g. 1 SED) is effective in generating or maintaining a healthy vitamin D status. However, due to limitations that include possible

  15. Effects of prenatal exposure to surface-coated nanosized titanium dioxide (UV-Titan. A study in mice

    Directory of Open Access Journals (Sweden)

    Vibenholt Anni

    2010-06-01

    Full Text Available Abstract Background Engineered nanoparticles are smaller than 100 nm and designed to improve or achieve new physico-chemical properties. Consequently, also toxicological properties may change compared to the parent compound. We examined developmental and neurobehavioral effects following maternal exposure to a nanoparticulate UV-filter (UV-titan L181. Methods Time-mated mice (C57BL/6BomTac were exposed by inhalation 1h/day to 42 mg/m3 aerosolized powder (1.7·106 n/cm3; peak-size: 97 nm on gestation days 8-18. Endpoints included: maternal lung inflammation; gestational and litter parameters; offspring neurofunction and fertility. Physicochemical particle properties were determined to provide information on specific exposure and deposition. Results Particles consisted of mainly elongated rutile titanium dioxide (TiO2 with an average crystallite size of 21 nm, modified with Al, Si and Zr, and coated with polyalcohols. In exposed adult mice, 38 mg Ti/kg was detected in the lungs on day 5 and differential cell counts of bronchoalveolar lavage fluid revealed lung inflammation 5 and 26-27 days following exposure termination, relative to control mice. As young adults, prenatally exposed offspring tended to avoid the central zone of the open field and exposed female offspring displayed enhanced prepulse inhibition. Cognitive function was unaffected (Morris water maze test. Conclusion Inhalation exposure to nano-sized UV Titan dusts induced long term lung inflammation in time-mated adult female mice. Gestationally exposed offspring displayed moderate neurobehavioral alterations. The results are discussed in the light of the observed particle size distribution in the exposure atmosphere and the potential pathways by which nanoparticles may impart changes in fetal development.

  16. Effects of prenatal exposure to surface-coated nanosized titanium dioxide (UV-Titan). A study in mice.

    Science.gov (United States)

    Hougaard, Karin S; Jackson, Petra; Jensen, Keld A; Sloth, Jens J; Löschner, Katrin; Larsen, Erik H; Birkedal, Renie K; Vibenholt, Anni; Boisen, Anne-Mette Z; Wallin, Håkan; Vogel, Ulla

    2010-06-14

    Engineered nanoparticles are smaller than 100 nm and designed to improve or achieve new physico-chemical properties. Consequently, also toxicological properties may change compared to the parent compound. We examined developmental and neurobehavioral effects following maternal exposure to a nanoparticulate UV-filter (UV-titan L181). Time-mated mice (C57BL/6BomTac) were exposed by inhalation 1h/day to 42 mg/m(3) aerosolized powder (1.7.10(6) n/cm(3); peak-size: 97 nm) on gestation days 8-18. Endpoints included: maternal lung inflammation; gestational and litter parameters; offspring neurofunction and fertility. Physicochemical particle properties were determined to provide information on specific exposure and deposition. Particles consisted of mainly elongated rutile titanium dioxide (TiO2) with an average crystallite size of 21 nm, modified with Al, Si and Zr, and coated with polyalcohols. In exposed adult mice, 38 mg Ti/kg was detected in the lungs on day 5 and differential cell counts of bronchoalveolar lavage fluid revealed lung inflammation 5 and 26-27 days following exposure termination, relative to control mice. As young adults, prenatally exposed offspring tended to avoid the central zone of the open field and exposed female offspring displayed enhanced prepulse inhibition. Cognitive function was unaffected (Morris water maze test). Inhalation exposure to nano-sized UV Titan dusts induced long term lung inflammation in time-mated adult female mice. Gestationally exposed offspring displayed moderate neurobehavioral alterations. The results are discussed in the light of the observed particle size distribution in the exposure atmosphere and the potential pathways by which nanoparticles may impart changes in fetal development.

  17. Poly(ADP-ribose) polymerase inhibitors suppress UV-induced human immunodeficiency virus type 1 gene expression at the posttranscriptional level

    International Nuclear Information System (INIS)

    Yamagoe, S.; Kohda, T.; Oishi, M.

    1991-01-01

    Gene expression of human immunodeficiency virus type 1 (HIV-1) is induced not only by trans activation mediated through a gene product (tat) encoded by the virus but also by treatment of virus-carrying cells with DNA-damaging agents such as UV light. Employing an artificially constructed DNA in which the chloramphenicol acetyltransferase gene was placed under the control of the HIV-1 long terminal repeat, we analyzed the induction process in HeLa cells and found that inhibitors of poly(ADP-ribose) polymerase suppressed UV-induced HIV-1 gene expression but not tat-mediated expression. We also found that suppression occurs at the posttranscriptional level. These results indicate that HIV-1 gene expression is activated by at least two different mechanisms, one of which involves poly-ADP ribosylation. A possible new role of poly-ADP ribosylation in the regulation of specific gene expression is also discussed

  18. UV-assisted synthesis of surface modified mesoporous TiO{sub 2}/G microspheres and its electrochemical performances in lithium ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Xiaoling; Zeng, Min, E-mail: zengmin@swust.edu.cn; Li, Jing; Li, Fuyun

    2017-01-15

    Highlights: • We synthesize the surface modified mesoporous TiO{sub 2}/G microspheres, which possess high surface area with 258 m{sup 2} g{sup −1} and narrow pore size at about 7.8 nm. • The surface reaction mechanism of the UV-assisted synthesis mesoporous TiO{sub 2}/G microspheres has been explored. • The as-made TiO{sub 2}/G microspheres exhibit excellent electrochemical performances and deliver a capacity of 141 mAh g{sup −1} upon 100 cycles even at 1 C. - Abstract: Three-dimensional mesoporous TiO{sub 2}/graphene (TiO{sub 2}/G) microspheres have been successfully synthesized through a simple UV-assisted method of reduced graphene oxide with hydrazine. The as-made surface modified mesoporous TiO{sub 2}/G microspheres possess large surface area and exhibit a high initial discharge capacity of 220 mAh g{sup −1} and retain 84% (∼185 mAh g{sup −1}) of reversible capacity over 100 cycles at a rate of 0.2C. In addition, TiO{sub 2}/G microspheres display improved cyclic performance, excellent rate capability and enhanced electrical conductivity, which are superior to the bare TiO{sub 2} microspheres. Furthermore, TiO{sub 2}/G microspheres can achieve a reversible capacity of 141 mAh g{sup −1} upon 100 cycles even at the 1C rate. We believe that the mesoporous TiO{sub 2}/G microspheres are expected to be a promising high performance anode material for the next generation lithium ion batteries.

  19. Exploring the critical dependence of adsorption of various dyes on the degradation rate using Ln3+-TiO2 surface under UV/solar light

    International Nuclear Information System (INIS)

    Devi, L. Gomathi; Kumar, S. Girish

    2012-01-01

    Graphical abstract: The surface reactive acidic sites enhances on doping with rare earth ions which facilitates efficient adsorption of the dye molecules on the catalyst surface. In addition, the nature of the dopant, its concentration and electronic configuration additionally contributes to the overall efficiency. Highlights: ► The degradation of structurally different anionic dyes under different pH conditions is reported. ► Pre adsorption of pollutant on catalyst surface is vital for efficient photocatalysis. ► Adsorption of dye on the catalyst surface depends on the substituent's attached to it. ► The dopant with half filled electronic configuration served as shallow traps for charge carriers. - Abstract: The degradation of structurally different anionic dyes like Alizarin Red S (ARS) Amaranth (AR), Brilliant Yellow (BY), Congo Red (CR), Fast Red (FR), Methyl Orange (MO), and Methyl Red (MR) were carried out using Ln 3+ (Ln 3+ = La 3+ , Ce 3+ and Gd 3+ ) doped TiO 2 at different pH conditions under UV/solar light. All the anionic dyes underwent rapid degradation at acidic pH, while resisted at alkaline conditions due to the adsorptive tendency of these dyes on the catalyst surface at different pH conditions. Gd 3+ (0.15 mol%)-TiO 2 exhibited better activity compared to other photocatalyst ascribed to half filled electronic configuration of Gd 3+ ions. It is proposed that Ln 3+ serves only as charge carrier traps under UV light, while it also act as visible light sensitizers under solar light. Irrespective of the catalyst and excitation source, the dye degradation followed the order: AR > FR > MO > MR > ARS > BY > CR. The results suggest that pre-adsorption of the pollutant is vital for efficient photocatalysis which is dependent on the nature of the substituent's group attached to the dye molecule.

  20. Photocatalytic performance of cylindrical reactor inserted with UV light-emitting-diodes for purification of low-level toxic volatile organic compounds

    International Nuclear Information System (INIS)

    Jo, Wan K.; Kang, Hyun J.

    2012-01-01

    Highlights: ► Photocatalyst baked at 350 °C exhibited the highest BTEX degradation efficiency. ► Conventional lamp evidenced a higher degradation efficiency compared to LEDs. ► LEDs was more energy-efficient than conventional lamp for BTEX degradation. ► As the residence time increased, the average degradation efficiency increased. - Abstract: The present study investigated the photocatalytic performance of a cylindrical reactor inserted with UV light-emitting-diodes for the decomposition of low-level (0.1 ppm) gas-phase organic compounds (benzene, toluene, ethyl benzene and xylene (BTEX)). The morphological and optical properties of photocatalysts (Degussa P-25 TiO 2 ) baked at different temperatures were determined using a range of spectral instruments. The photocatalyst baked at 350 °C exhibited the highest conversion efficiencies for both benzene and toluene (81 and ∼100%, respectively). The conventional lamp showed a higher conversion efficiency for benzene compared to the 380-nm UV-LED and a higher conversion efficiency for benzene and toluene than the 365-nm UV-LED. However, the ratios of conversion efficiency to electric power consumption were 2.5–3.0 times higher for the latter light source than the former source. Moreover, as the residence time increased from 0.2 to 1.2 min, the average conversion efficiencies for BTEX of the 3-h photocatalytic process increased from nearly zero to 81%, 7 to nearly 100%, 20 to nearly 100%, and 29–30 to nearly 100%, respectively. The cylindrical photocatalytic reactor inserted with UV-LEDs could be energy-efficiently applied for the decomposition of low-level toxic compounds after optimization of the operating conditions.

  1. Photocatalytic performance of cylindrical reactor inserted with UV light-emitting-diodes for purification of low-level toxic volatile organic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Wan K., E-mail: wkjo@knu.ac.kr [Department of Environmental Engineering, Kyungpook National University, Daegu, 702-701 (Korea, Republic of); Kang, Hyun J., E-mail: khj435@naver.com [Department of Environmental Engineering, Kyungpook National University, Daegu, 702-701 (Korea, Republic of)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer Photocatalyst baked at 350 Degree-Sign C exhibited the highest BTEX degradation efficiency. Black-Right-Pointing-Pointer Conventional lamp evidenced a higher degradation efficiency compared to LEDs. Black-Right-Pointing-Pointer LEDs was more energy-efficient than conventional lamp for BTEX degradation. Black-Right-Pointing-Pointer As the residence time increased, the average degradation efficiency increased. - Abstract: The present study investigated the photocatalytic performance of a cylindrical reactor inserted with UV light-emitting-diodes for the decomposition of low-level (0.1 ppm) gas-phase organic compounds (benzene, toluene, ethyl benzene and xylene (BTEX)). The morphological and optical properties of photocatalysts (Degussa P-25 TiO{sub 2}) baked at different temperatures were determined using a range of spectral instruments. The photocatalyst baked at 350 Degree-Sign C exhibited the highest conversion efficiencies for both benzene and toluene (81 and {approx}100%, respectively). The conventional lamp showed a higher conversion efficiency for benzene compared to the 380-nm UV-LED and a higher conversion efficiency for benzene and toluene than the 365-nm UV-LED. However, the ratios of conversion efficiency to electric power consumption were 2.5-3.0 times higher for the latter light source than the former source. Moreover, as the residence time increased from 0.2 to 1.2 min, the average conversion efficiencies for BTEX of the 3-h photocatalytic process increased from nearly zero to 81%, 7 to nearly 100%, 20 to nearly 100%, and 29-30 to nearly 100%, respectively. The cylindrical photocatalytic reactor inserted with UV-LEDs could be energy-efficiently applied for the decomposition of low-level toxic compounds after optimization of the operating conditions.

  2. Surface-Level Diversity and Decision-Making in Groups: When Does Deep-Level Similarity Help?

    OpenAIRE

    2006-01-01

    Abstract We examined how surface-level diversity (based on race) and deep-level similarities influenced three-person decision-making groups on a hidden-profile task. Surface-level homogeneous groups perceived their information to be less unique and spent less time on the task than surface-level diverse groups. When the groups were given the opportunity to learn about their deep-level similarities prior to t...

  3. An examination of endoparasites and fecal testosterone levels in flying squirrels (Glaucomys spp.) using high performance liquid chromatography-ultra-violet (HPLC-UV).

    Science.gov (United States)

    Waksmonski, Sarah N; Huffman, Justin M; Mahan, Carolyn G; Steele, Michael A

    2017-08-01

    The immuno-competence hypothesis proposes that higher levels of testosterone increases the susceptibility to parasitism. Here we examined the testosterone levels in two species of flying squirrels ( Glaucomys ): one known to regularly host a nematode species ( Strongyloides robustus ) without ill effects ( G. volans ) and a closely related species that is considered negatively affected by the parasite. We quantified fecal testosterone levels in northern and southern flying squirrels ( G. sabrinus, G. volans ) with high-performance liquid chromatography-ultraviolet spectroscopy (HPLC-UV), and compared levels to endoparasites detected in individual squirrels. Qualitatively, we found highest levels of testosterone in male northern flying squirrels infected with Strongyloides robustus . This analytical approach represents an alternative and equally reliable method to using enzyme-linked immunosorbent assay (ELISA), for detecting and quantifying fecal testosterone levels.

  4. An examination of endoparasites and fecal testosterone levels in flying squirrels (Glaucomys spp. using high performance liquid chromatography-ultra-violet (HPLC-UV

    Directory of Open Access Journals (Sweden)

    Sarah N. Waksmonski

    2017-08-01

    Full Text Available The immuno-competence hypothesis proposes that higher levels of testosterone increases the susceptibility to parasitism. Here we examined the testosterone levels in two species of flying squirrels (Glaucomys: one known to regularly host a nematode species (Strongyloides robustus without ill effects (G. volans and a closely related species that is considered negatively affected by the parasite. We quantified fecal testosterone levels in northern and southern flying squirrels (G. sabrinus, G. volans with high-performance liquid chromatography-ultraviolet spectroscopy (HPLC-UV, and compared levels to endoparasites detected in individual squirrels. Qualitatively, we found highest levels of testosterone in male northern flying squirrels infected with Strongyloides robustus. This analytical approach represents an alternative and equally reliable method to using enzyme-linked immunosorbent assay (ELISA, for detecting and quantifying fecal testosterone levels.

  5. Adsorption characteristics of Au nanoparticles onto poly(4-vinylpyridine) surface revealed by QCM, AFM, UV/vis, and Raman scattering spectroscopy.

    Science.gov (United States)

    Kim, Kwan; Ryoo, Hyunwoo; Lee, Yoon Mi; Shin, Kuan Soo

    2010-02-15

    In this work, we report that the adsorption and aggregation processes of Au nanoparticles on a polymer surface can be monitored by means of surface-enhanced Raman scattering (SERS) spectroscopy. Specifically, we were able to analyze the adsorption process of citrate-stabilized Au nanoparticles onto a film of poly(4-vinylpyridine) (P4VP) by taking a series of SERS spectra, during the self-assembly of Au nanoparticles onto the polymer film. In order to better analyze the SERS spectra, we separately conducted quartz crystal microbalance (QCM), UV/vis spectroscopy, and atomic force microscope (AFM) measurements. The adsorption kinetics revealed by QCM under the in situ conditions was in fair agreement with that determined by the ex situ AFM measurement. The number of Au nanoparticles adsorbed on P4VP increased almost linearly with time: 265 Au nanoparticles per 1microm(2) were adsorbed on the P4VP film after 6h of immersion. The SERS signal measured in the ex situ condition showed a more rapid increase than that of QCM; however, its increasing pattern was quite similar to that of UV/vis absorbance at longer wavelengths, suggesting that Au nanoparticles actually became agglomerated on P4VP. Copyright 2009 Elsevier Inc. All rights reserved.

  6. Impact of fouling on UV effectiveness

    International Nuclear Information System (INIS)

    Dykstra, T.S.; Chauret, C.

    2002-01-01

    In recent years ultraviolet light has gained in popularity as an attractive disinfection alternative due to its ability to inactivate bacteria and viruses. UV light has the potential to inactivate Cryptosporidium parvum and Giardia lamblia with a very low potential for the formation of harmful disinfection by-products. Previous studies have reported that particulate material present in the water can act to reduce the exposure of UV light to the receiving waters and that the interference of organic particles can serve to protect bacteria and viruses from intended disinfection. Disinfection capacity can also be reduced by organics in the source water that can accumulate on the surface of quartz sleeves. The purpose of this study was to determine the ability of a medium pressure UV light, at drinking water treatment levels, to inactivate MS 2 bacteriophage after a quartz tube has been fouled with organic rich source water for a 12- week period. To this end the inactivation of MS 2 was determined under clean and fouled conditions, in the presence and absence of humic rich water. The effect of lamp age on inactivation was also investigated. The results suggest that organic fouling of a quartz tube has a significant impact on the disinfection capacity of a medium pressure UV lamp. The presence of organics in the source water also plays a significant role in reducing the capacity of UV for bacterial and viral disinfection. Lamp age also seems to have some effect on the efficiency of UV disinfection. (author)

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

    Science.gov (United States)

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

    2001-12-01

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

  8. UV-B Radiation Contributes to Amphibian Population Declines

    Science.gov (United States)

    Blaustein, Andrew

    2007-05-01

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

  9. An in vitro strategy to evaluate the phototoxicity of solar UV at the molecular and cellular level: application to photoprotection assessment.

    Science.gov (United States)

    Marrot, L; Belaidi, J P; Chaubo, C; Meunier, J R; Perez, P; Agapakis-Causse, C

    1998-09-01

    Skin cancers are among the most common human cancers and have an increasing incidence. The ultraviolet radiation components of sunlight play a major role in skin tumor induction and development. Cellular DNA has been identified as a target for most of the biological effects of UV, and the induction of photodamage is considered as the initiating step of photocarcinogenesis. Thus, effective photoprotection of DNA against harmful overex-posure to solar UV is a critical issue. The efficiency of a sunscreen is usually tested with respect to its ability to prevent skin erythema, but conceivably, more data are required at the molecular and cellular level in order to ascertain protection against photocarcinogenic risk. In the present study, we define a strategy based on the use of various in vitro models and solar-simulated light to evaluate photodamage and photoprotection: -Supercoiled circular plasmid DNA for detection of structural alterations. -The yeast Saccharomyces cerevisiae to evaluate cytotoxicity and genotoxicity. -The single-cell gel electrophoresis or comet assay to determine DNA damage and DNA repair in human keratinocytes. -p53 expression as a hallmark for genotoxic stress. -Induction of pigmentation in human melanocytes. In conditions where light source, spectrum and control of radiation delivery were precisely defined, we have demonstrated that the wide spectrum UVA sunscreen Mexoryl SX protects from the cytotoxicity and genotoxicity of solar UV.

  10. Building unique surface structure on aramid fibers through a green layer-by-layer self-assembly technique to develop new high performance fibers with greatly improved surface activity, thermal resistance, mechanical properties and UV resistance

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Lifang; Yuan, Li; Guan, Qingbao; Gu, Aijuan, E-mail: ajgu@suda.edu.cn; Liang, Guozheng, E-mail: lgzheng@suda.edu.cn

    2017-07-31

    Highlights: • A green technology is setup to build unique surface structure on aramid fiber (AF). • The method is layer-by-layer self-assembling SiO{sub 2} and layered double hydroxide. • The surface of AF is adjustable by controlling the self-assembly cycle number. • New AF has excellent surface activity, anti-UV, thermal and mechanical properties. • The origin behind attractive performances of new AFs was intensively studied. - Abstract: Combining green preparation and high performance is becoming the direction of sustainable development of materials. How to simultaneously overcome the two bottlenecks (poor surface activity and UV resistance) of aramid fibers (AFs) while improving thermal and mechanical properties through a green process is still an interesting issue with big challenge. Herein, new AFs (BL-AFs) were prepared by alternately self-assembling SiO{sub 2} and MgAlFe layered double hydroxide (LDH) on surfaces of AFs, successively, through a green layer-by-layer (LBL) self-assembly technique without using high temperature and organic solvent. The structures and properties of BL-AFs were systematically studied, which are controllable by adjusting the number of self-assembly cycle. The new fibers with three or more self-assembly cycles have remarkably improved surface activity, thermal resistance, mechanical properties and UV resistance compared with AFs. Typically, with three self-assembly cycles, the initial degradation temperature and char yield of the new fiber (3BL-AF) are as high as 552.9 °C and 81.2%, about 92 °C and 25.2% higher than those of AF, respectively; after 168 h-UV irradiation, the retention of tensile performances of 3BL-AF fiber is as high as 91–95%, about 29–14% higher than that of AF, showing the best overall performances among all modified AFs prepared using a green technique reported so far. The origin behind the attractive performances of BL-AFs is revealed through correlating with structures of original and

  11. Alleviation of UV-B stress in Arabidopsis using tea catechins | Lee ...

    African Journals Online (AJOL)

    Ultraviolet-B (UV-B) has been confirmed to be harmful to living organisms and it is of concern that the amount of UV-B radiation reaching the earth's surface is increasing because of the depletion of the stratospheric ozone layer. Effect of different levels of tea catechins on morphological damage and expression of chalcone ...

  12. Application of response surface methodology for optimization of natural organic matter degradation by UV/H2O2 advanced oxidation process.

    Science.gov (United States)

    Rezaee, Reza; Maleki, Afshin; Jafari, Ali; Mazloomi, Sajad; Zandsalimi, Yahya; Mahvi, Amir H

    2014-01-01

    In this research, the removal of natural organic matter from aqueous solutions using advanced oxidation processes (UV/H2O2) was evaluated. Therefore, the response surface methodology and Box-Behnken design matrix were employed to design the experiments and to determine the optimal conditions. The effects of various parameters such as initial concentration of H2O2 (100-180 mg/L), pH (3-11), time (10-30 min) and initial total organic carbon (TOC) concentration (4-10 mg/L) were studied. Analysis of variance (ANOVA), revealed a good agreement between experimental data and proposed quadratic polynomial model (R(2) = 0.98). Experimental results showed that with increasing H2O2 concentration, time and decreasing in initial TOC concentration, TOC removal efficiency was increased. Neutral and nearly acidic pH values also improved the TOC removal. Accordingly, the TOC removal efficiency of 78.02% in terms of the independent variables including H2O2 concentration (100 mg/L), pH (6.12), time (22.42 min) and initial TOC concentration (4 mg/L) were optimized. Further confirmation tests under optimal conditions showed a 76.50% of TOC removal and confirmed that the model is accordance with the experiments. In addition TOC removal for natural water based on response surface methodology optimum condition was 62.15%. This study showed that response surface methodology based on Box-Behnken method is a useful tool for optimizing the operating parameters for TOC removal using UV/H2O2 process.

  13. Specific behavior of the p-aminothiophenol--silver sol system in their Ultra-Violet-Visible (UV-Visible) and Surface Enhanced Raman (SERS) spectra.

    Science.gov (United States)

    Firkala, Tamás; Tálas, Emília; Mihály, Judith; Imre, Tímea; Kristyán, Sándor

    2013-11-15

    The UV-Visible and Surface Enhanced Raman Spectroscopy (SERS) behavior of silver sol (a typical SERS agent) were studied in the presence of different bifunctional thiols such as p-aminothiophenol, p-mercaptobenzoic acid, p-nitrothiophenol, p-aminothiophenol hydrochloride, and 2-mercaptoethylamine hydrochloride in diluted aqueous solution. Our results confirm that the p-aminothiophenol induced aggregation of citrate stabilized silver colloid originates from its electrostatic nature, as well as the azo-bridge formation cannot be the reason of the observed time dependent UV-Visible spectra. Based on our parallel SERS and electrospray ionization mass spectrometry measurements, we have concluded that certain amount of oxidized form of the probe molecule has to be present for the so-called b2-mode enhancement in the SERS spectrum of p-aminothiophenol. Our findings seem to support the idea that the azo-bridge formation is responsible for the b2-mode enhancement in the SERS spectrum of p-aminothiophenol. Copyright © 2013 Elsevier Inc. All rights reserved.

  14. A combined Surface Enhanced Raman Spectroscopy (SERS)/UV-vis approach for the investigation of dye content in commercial felt tip pens inks.

    Science.gov (United States)

    Saviello, Daniela; Trabace, Maddalena; Alyami, Abeer; Mirabile, Antonio; Giorgi, Rodorico; Baglioni, Piero; Iacopino, Daniela

    2018-05-01

    The development of protocols for the protection of the large patrimony of works of art created by felt tip pen media since the 1950's requires detailed knowledge of the main dyes constituting commercial ink mixtures. In this work Surface Enhanced Raman Scattering (SERS) and UV-vis spectroscopy were used for the first time for the systematic identification of dye composition in commercial felt tip pens. A large selection of pens comprising six colors of five different brands was analyzed. Intense SERS spectra were obtained for all colors, allowing identification of main dye constituents. Poinceau 4R and Eosin dyes were found to be the main constituents of red and pink colors; Rhodamine and Tartrazine were found in orange and yellow colors; Erioglaucine was found in green and blue colors. UV-vis analysis of the same inks was used to support SERS findings but also to unequivocally assign some uncertain dye identifications, especially for yellow and orange colors. The spectral data of all felt tip pens collected through this work were assembled in a database format. The data obtained through this systematic investigation constitute the basis for the assembly of larger reference databases that ultimately will support the development of conservation protocols for the long term preservation of modern art collections. Copyright © 2018 Elsevier B.V. All rights reserved.

  15. Effects of UV radiation on phytoplankton

    Science.gov (United States)

    Smith, Raymond C.; Cullen, John J.

    1995-07-01

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

  16. Maximum surface level and temperature histories for Hanford waste tanks

    International Nuclear Information System (INIS)

    Flanagan, B.D.; Ha, N.D.; Huisingh, J.S.

    1994-01-01

    Radioactive defense waste resulting from the chemical processing of spent nuclear fuel has been accumulating at the Hanford Site since 1944. This waste is stored in underground waste-storage tanks. The Hanford Site Tank Farm Facilities Interim Safety Basis (ISB) provides a ready reference to the safety envelope for applicable tank farm facilities and installations. During preparation of the ISB, tank structural integrity concerns were identified as a key element in defining the safety envelope. These concerns, along with several deficiencies in the technical bases associated with the structural integrity issues and the corresponding operational limits/controls specified for conduct of normal tank farm operations are documented in the ISB. Consequently, a plan was initiated to upgrade the safety envelope technical bases by conducting Accelerated Safety Analyses-Phase 1 (ASA-Phase 1) sensitivity studies and additional structural evaluations. The purpose of this report is to facilitate the ASA-Phase 1 studies and future analyses of the single-shell tanks (SSTs) and double-shell tanks (DSTs) by compiling a quantitative summary of some of the past operating conditions the tanks have experienced during their existence. This report documents the available summaries of recorded maximum surface levels and maximum waste temperatures and references other sources for more specific data

  17. UV-induced carbon monoxide emission from sand and living vegetation

    DEFF Research Database (Denmark)

    Bruhn, Dan; Albert, Kristian Rost; Mikkelsen, Teis Nørgaard

    2012-01-01

    The global burden of carbon monoxide, CO, is rather uncertain. In this paper we address the potential of UV-induced CO emission by terrestrial surfaces. Real-time measurements of [CO] were made with a cavity enhanced laser connected in closed loop to either an ecosystem chamber or a leaf scale...... chamber. Sand and leaves of all examined plant species exhibited emission of CO in response to artificial UV-radiation and the UV-component of natural solar radiation. The UV-induced rate of CO emission exhibited a rather low dependence on temperature, indicating an abiotic process. The emission of CO...... in response to the UV-component of natural solar radiation was also evident at the ecosystem scale. When scaled to the global level, the UV-induced emission of CO by the major types of terrestrial surfaces, living leaves and soil (here represented by sand), amounts up to 28 Tg yr−1. This source has...

  18. Surface modification of TiO2 with g-C3N4 for enhanced UV and visible photocatalytic activity

    International Nuclear Information System (INIS)

    Lei, Juying; Chen, Ying; Shen, Fan; Wang, Lingzhi; Liu, Yongdi; Zhang, Jinlong

    2015-01-01

    Highlights: • g-C 3 N 4 /TiO 2 was prepared by a one-step preparation under mild conditions. • Photocatalysts showed excellent activity under both UV and visible light. • A neat surface modification process is proved, excluding influence of N doping. • Two photocatalytic mechanisms under different wavelengths are proposed. • A wide range of available wavelengths would greatly improve practicability of TiO 2 . - Abstract: g-C 3 N 4 modified TiO 2 composites were prepared through a simple calcination process of anatase and cyanamide. The as-prepared samples were characterized by X-ray diffraction (XRD), diffuse reflectance spectrophotometry (DRS), fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), thermogravimetry differential thermal analysis (TG–DTA) and X-ray photoelectron spectroscopy (XPS), proving a successful modification of TiO 2 with g-C 3 N 4 . Photodegradation of acid orange 7 (AO7) was used to evaluate the photocatalytic activities of the composites, showing excellent activity of them under both visible and UV light. In addition, base treatment was then introduced to investigate the interaction between g-C 3 N 4 and TiO 2 . After removing the g-C 3 N 4 modified on TiO 2 by base, no nitrogen doping is found in TiO 2 lattice, demonstrating the g-C 3 N 4 was surface attached on TiO 2 and attributing all improvement of photocatalytic activity of g-C 3 N 4 /TiO 2 composite to the synergy between the two semiconductors

  19. Development of Cotton Fabrics with Durable UV Protective and Self-cleaning Property by Deposition of Low TiO2 Levels through Sol-gel Process.

    Science.gov (United States)

    Mishra, Anu; Butola, Bhupendra Singh

    2018-01-19

    In this article, the deposition of TiO 2 on cotton fabric using sol-gel technique has been described. Various process routes (pad-dry-cure, pad-dry-hydrothermal and pad-dry-solvothermal) were examined to impart a stable coating of TiO 2 on fabric. The role of precursor concentration, process temperature and time of treatment were studied to aim at a wash durable, UV protective and self-cleaning property in the treated fabric. EDX and ICP-MS techniques were used to examine the add-on percentage of TiO 2 on cotton fabrics treated via different routes. It has been found that the TiO 2 remains largely amorphous and nondurable if it is given a short thermal treatment. To convert the deposited TiO 2 to its anatase crystal form, a prolonged hydrothermal treatment for at least 3 h needs to be given. TiO 2 deposition levels of less than 0.1% were found to be effective in imparting reasonable degree of UV protection and self-cleaning property to the cotton fabric. The self-cleaning ability of the treated fabric against coffee stain was also studied and was found to be related to the process route and the deposition levels of TiO 2 . © 2018 The American Society of Photobiology.

  20. Preparation of Dry Extract of Mikania glomerata Sprengel (Guaco and Determination of Its Coumarin Levels by Spectrophotometry and HPLC-UV

    Directory of Open Access Journals (Sweden)

    Maria da Penha Henriques do Amaral

    2012-08-01

    Full Text Available Guaco (Mikania glomerata Sprengel syrup is one of the most popular herbal medicines used to treat the symptoms of asthmatic bronchitis, cough and hoarseness. The coumarin 2H-1-benzopyran-2-one, is one of the major constituents of Guaco and contributes to its pharmacological effects. The pharmaceutical capsule form of dry extract of Guaco is recommended by the Brazilian Program of Medicinal Plants and Herbal Medicines and used in primary health care. In order to identify a new protocol to obtain the raw material for Guaco capsule production we evaluated two methods, including a freeze-drying process (lyophilization and the spray-dryer technique, as well as the use of two adjuvants, Maltodextrins and Aerosil®, in different concentrations. The coumarin levels of the dried extracts were analyzed by UV-spectrophotometry and HPLC-UV/DAD. The adjuvant Aerosil® 8% showed better dry powder physical appearance. Lyophilization was observed to be the best process to obtain the dry extract of Guaco based on the measured coumarin levels.

  1. Experimental study on source efficiencies for estimating surface contamination level

    International Nuclear Information System (INIS)

    Ichiji, Takeshi; Ogino, Haruyuki

    2008-01-01

    Source efficiency was measured experimentally for various materials, such as metals, nonmetals, flooring materials, sheet materials and other materials, contaminated by alpha and beta emitter radioactive nuclides. Five nuclides, 147 Pm, 60 Co, 137 Cs, 204 Tl and 90 Sr- 90 Y, were used as the beta emitters, and one nuclide 241 Am was used as the alpha emitter. The test samples were prepared by placing drops of the radioactive standardized solutions uniformly on the various materials using an automatic quantitative dispenser system from Musashi Engineering, Inc. After placing drops of the radioactive standardized solutions, the test materials were allowed to dry for more than 12 hours in a draft chamber with a hood. The radioactivity of each test material was about 30 Bq. Beta rays or alpha rays from the test materials were measured with a 2-pi gas flow proportional counter from Aloka Co., Ltd. The source efficiencies of the metals, nonmetals and sheet materials were higher than 0.5 in the case of contamination by the 137 Cs, 204 Tl and 90 Sr- 90 Y radioactive standardized solutions, higher than 0.4 in the case of contamination by the 60 Co radioactive standardized solution, and higher than 0.25 in the case of contamination by the alpha emitter the 241 Am radioactive standardized solution. These values were higher than those given in Japanese Industrial Standards (JIS) documents. In contrast, the source efficiencies of some permeable materials were lower than those given in JIS documents, because source efficiency varies depending on whether the materials or radioactive sources are wet or dry. This study provides basic data on source efficiency, which is useful for estimating the surface contamination level of materials. (author)

  2. Nanostructured Polymer Brushes by UV-Assisted Imprint Lithography and Surface-Initiated Polymerization for Biological Functions

    NARCIS (Netherlands)

    Benetti, Edmondo Maria; Acikgoz, C.; Sui, Xiaofeng; Vratzov, Boris; Hempenius, Mark A.; Huskens, Jurriaan; Vancso, Gyula J.

    2011-01-01

    Functional polymer brush nanostructures are obtained by combining step-and-flash imprint lithography (SFIL) with controlled, surface-initiated polymerization (CSIP). Patterning is achieved at length scales such that the smallest elements have dimensions in the sub-100 nm range. The patterns exhibit

  3. Extreme UV and X-ray scattering measurements from a rough LiF crystal surface characterized by electron micrography

    DEFF Research Database (Denmark)

    Alehyane; Arbaoui; Barchewitz

    1989-01-01

    XUV and X-ray scattering by a LiF crystal is measured. The angular distribution of the scattered radiation (ADSR) reveals characteristic features, side peaks or asymmetry. The surface of the sample is statistically characterized by a microdensitometer analysis of electron micrographs resolving th...

  4. Variable-focus microscopy and UV surface dissolution imaging as complementary techniques in intrinsic dissolution rate determination

    DEFF Research Database (Denmark)

    Ward, Adam; Walton, Karl; Box, Karl

    2017-01-01

    -SDI run, have been measured using a non-contact, optical, three-dimensional microscope based on focus variation, the Alicona Infinite Focus Microscope, with the aim of correlating the IDRs to the surface properties. Ibuprofen (IBU) was used as a model poorly-soluble drug. DSC and XRD were used to monitor...... possible polymorphic changes that may have occurred post-compaction and post-SDI run. IBUs IDR decreased from 0.033mg/min/cm(2) to 0.022mg/min/cm(2) from 10 to 20min, respectively, during the experiment. XRD and DSC showed no form changes during the SDI run. The surface topography images showed...

  5. Assessment of four methods to estimate surface UV radiation using satellite data, by comparison with ground measurements from four stations in Europe

    Science.gov (United States)

    Arola, Antti; Kalliskota, S.; den Outer, P. N.; Edvardsen, K.; Hansen, G.; Koskela, T.; Martin, T. J.; Matthijsen, J.; Meerkoetter, R.; Peeters, P.; Seckmeyer, G.; Simon, P. C.; Slaper, H.; Taalas, P.; Verdebout, J.

    2002-08-01

    Four different satellite-UV mapping methods are assessed by comparing them against ground-based measurements. The study includes most of the variability found in geographical, meteorological and atmospheric conditions. Three of the methods did not show any significant systematic bias, except during snow cover. The mean difference (bias) in daily doses for the Rijksinstituut voor Volksgezondheid en Milieu (RIVM) and Joint Research Centre (JRC) methods was found to be less than 10% with a RMS difference of the order of 30%. The Deutsches Zentrum für Luft- und Raumfahrt (DLR) method was assessed for a few selected months, and the accuracy was similar to the RIVM and JRC methods. It was additionally used to demonstrate how spatial averaging of high-resolution cloud data improves the estimation of UV daily doses. For the Institut d'Aéronomie Spatiale de Belgique (IASB) method the differences were somewhat higher, because of their original cloud algorithm. The mean difference in daily doses for IASB was about 30% or more, depending on the station, while the RMS difference was about 60%. The cloud algorithm of IASB has been replaced recently, and as a result the accuracy of the IASB method has improved. Evidence is found that further research and development should focus on the improvement of the cloud parameterization. Estimation of daily exposures is likely to be improved if additional time-resolved cloudiness information is available for the satellite-based methods. It is also demonstrated that further development work should be carried out on the treatment of albedo of snow-covered surfaces.

  6. A Molecular-Level Account of the Antigenic Hantaviral Surface

    Directory of Open Access Journals (Sweden)

    Sai Li

    2016-05-01

    Full Text Available Hantaviruses, a geographically diverse group of zoonotic pathogens, initiate cell infection through the concerted action of Gn and Gc viral surface glycoproteins. Here, we describe the high-resolution crystal structure of the antigenic ectodomain of Gn from Puumala hantavirus (PUUV, a causative agent of hemorrhagic fever with renal syndrome. Fitting of PUUV Gn into an electron cryomicroscopy reconstruction of intact Gn-Gc spike complexes from the closely related but non-pathogenic Tula hantavirus localized Gn tetramers to the membrane-distal surface of the virion. The accuracy of the fitting was corroborated by epitope mapping and genetic analysis of available PUUV sequences. Interestingly, Gn exhibits greater non-synonymous sequence diversity than the less accessible Gc, supporting a role of the host humoral immune response in exerting selective pressure on the virus surface. The fold of PUUV Gn is likely to be widely conserved across hantaviruses.

  7. Evaluation of the Levels of phthalate Ester Plasticizers in Surface ...

    African Journals Online (AJOL)

    ADOWIE PERE

    Gas chromatography (GC) coupled with mass ... Key words: phthalates, acid esters, plasticizers, Ethiope River, surface water, pollution ... waste and emissions arising from burning of refuse ... deepest inland waterways in Africa, is known for its ..... carbon nitride nanocomposites for the solid-phase extraction of phthalate ...

  8. Isotope shift studies in the spectra of gadolinium in UV region and term shifts of high even levels of Gd I

    International Nuclear Information System (INIS)

    Afzal, S.M.; Venugopalan, A.; Ahmad, S.A.

    1997-01-01

    Isotope shift Δσ( 156 Gd- 160 Gd) is reported in 70 spectral lines of neutral gadolinium atom (Gd I) in the 3290-3920 A region providing isotope shift data in UV lines of Gd I spectrum for the first time. The measurements were carried out on a photoelectric recording Fabry-Perot Spectrometer using highly enriched isotopic samples of gadolinium. Term isotope shifts ΔT( 156 Gd- 160 Gd) have been evaluated for 48 high lying even parity energy levels of Gd I using this data; new ΔT values have been obtained for 24 levels. Electronic configurations 4f 7 5d6s6p, 4f 7 5d 2 6p and 4f 8 5d6s assigned earlier to these even levels have been either confirmed or configuration mixing pointed out in some of these levels. Probable assignment of 4f 8 5d6s configuration to 8 even levels between 32930 and 35500 cm -1 have been confirmed. (orig.)

  9. The effect of radiation-thermal treatment on the physicochemical properties of the Ni-Mo/Al2O3 hydrotreatment catalyst. II. UV-Vis diffuse reflectance spectra of surface compounds after irradiation

    International Nuclear Information System (INIS)

    Solovetskii, Yu.I.; Miroshinichenko, I.I.; Lunin, V.V.

    1993-01-01

    Radiation-thermal damage of the surface and the active metal phases of hydrodesulfurization Ni-Mo/Al 2 O 3 catalysts by a fast electron beam of up to 2.0 MeV energy was studied. UV-Vis diffuse reflectance spectra of the industrial and model coked systems after radiation-thermal treatment were measured. 14 refs., 2 figs

  10. Low levels of glutathione are sufficient for survival of keratinocytes after UV irradiation and for healing of mouse skin wounds.

    Science.gov (United States)

    Telorack, Michèle; Abplanalp, Jeannette; Werner, Sabine

    2016-08-01

    Reduced levels of the cellular antioxidant glutathione are associated with premature skin aging, cancer and impaired wound healing, but the in vivo functions of glutathione in the skin remain largely unknown. Therefore, we analyzed mice lacking the modifier subunit of the glutamate cysteine ligase (Gclm), the enzyme that catalyzes the rate-limiting step of glutathione biosynthesis. Glutathione levels in the skin of these mice were reduced by 70 %. However, neither skin development and homeostasis, nor UVA- or UVB-induced apoptosis in the epidermis were affected. Histomorphometric analysis of excisional wounds did not reveal wound healing abnormalities in young Gclm-deficient mice, while the area of hyperproliferative epithelium as well as keratinocyte proliferation were affected in aged mice. These findings suggest that low levels of glutathione are sufficient for wound repair in young mice, but become rate-limiting upon aging.

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

    OpenAIRE

    Arrage, Andrew Anthony

    1991-01-01

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

  12. STS Observations of Landau Levels at Graphite Surfaces

    OpenAIRE

    Matsui, T.; Kambara, H.; Niimi, Y.; Tagami, K.; Tsukada, M.; Fukuyama, Hiroshi

    2004-01-01

    Scanning tunneling spectroscopy measurements were made on surfaces of two different kinds of graphite samples, Kish graphite and highly oriented pyrolytic graphite (HOPG), at very low temperatures and in high magnetic fields. We observed a series of peaks in the tunnel spectra, which grow with increasing field, both at positive and negative bias voltages. These are associated with Landau quantization of the quasi two-dimensional electrons and holes in graphite in magnetic fields perpendicular...

  13. CHEMICAL REACTIONS ON ADSORBING SURFACE: KINETIC LEVEL OF DESCRIPTION

    Directory of Open Access Journals (Sweden)

    P.P.Kostrobii

    2003-01-01

    Full Text Available Based on the effective Hubbard model we suggest a statistical description of reaction-diffusion processes for bimolecular chemical reactions of gas particles adsorbed on the metallic surface. The system of transport equations for description of particles diffusion as well as reactions is obtained. We carry out the analysis of the contributions of all physical processes to the formation of diffusion coefficients and chemical reactions constants.

  14. UV lithography-based protein patterning on silicon: Towards the integration of bioactive surfaces and CMOS electronics

    Energy Technology Data Exchange (ETDEWEB)

    Lenci, S., E-mail: silvia.lenci@iet.unipi.it [Dipartimento di Ingegneria dell' Informazione, via G.Caruso 16, Pisa I-56122 (Italy); Tedeschi, L. [Istituto di Fisiologia Clinica - CNR, via G. Moruzzi 1, Pisa I-56124 (Italy); Pieri, F. [Dipartimento di Ingegneria dell' Informazione, via G.Caruso 16, Pisa I-56122 (Italy); Domenici, C. [Istituto di Fisiologia Clinica - CNR, via G. Moruzzi 1, Pisa I-56124 (Italy)

    2011-08-01

    A simple and fast methodology for protein patterning on silicon substrates is presented, providing an insight into possible issues related to the interaction between biological and microelectronic technologies. The method makes use of standard photoresist lithography and is oriented towards the implementation of biosensors containing Complementary Metal-Oxide-Semiconductor (CMOS) conditioning circuitry. Silicon surfaces with photoresist patterns were prepared and hydroxylated by means of resist- and CMOS backend-compatible solutions. Subsequent aminosilane deposition and resist lift-off in organic solvents resulted into well-controlled amino-terminated geometries. The discussion is focused on resist- and CMOS-compatibility problems related to the used chemicals. Some samples underwent gold nanoparticle (Au NP) labeling and Scanning Electron Microscopy (SEM) observation, in order to investigate the quality of the silane layer. Antibodies were immobilized on other samples, which were subsequently exposed to a fluorescently labeled antigen. Fluorescence microscopy observation showed that this method provides spatially selective immobilization of protein layers onto APTES-patterned silicon samples, while preserving protein reactivity inside the desired areas and low non-specific adsorption elsewhere. Strong covalent biomolecule binding was achieved, giving stable protein layers, which allows stringent binding conditions and a good binding specificity, really useful for biosensing.

  15. Structural dependence of the 5d-metal surface energies as deduced from surface core-level shift measurements

    International Nuclear Information System (INIS)

    Mrartensson, N.; Saalfeld, H.B.; Kuhlenbeck, H.; Neumann, M.

    1989-01-01

    Surface core-level shift measurements performed at the BESSY storage ring yield -0.41(2) eV for Os(0001) and 0.00(10) eV for Re(0001). An analysis of the surface shifts in the 5d transition series shows that the surface energy as a function of Z has a maximum at lower Z for the bcc phase than for the fcc-hcp phases, at W and between Re and Os, respectively

  16. GHRSST Level 4 DMI_OI Global Foundation Sea Surface Temperature Analysis (GDS version 2)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis produced daily on an operational basis by the Danish...

  17. GHRSST Level 4 MUR North America Regional Foundation Sea Surface Temperature Analysis (GDS version 1)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis produced as a retrospective dataset at the JPL Physical...

  18. GHRSST Level 4 OSPO Global Nighttime Foundation Sea Surface Temperature Analysis (GDS version 2)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis produced daily on an operational basis at the Office of...

  19. GHRSST Level 4 AVHRR_AMSR_OI Global Blended Sea Surface Temperature Analysis (GDS version 1)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) global Level 4 sea surface temperature analysis produced daily on a 0.25 degree grid at the NOAA...

  20. GHRSST Level 4 ODYSSEA Mediterranean Sea Regional Foundation Sea Surface Temperature Analysis (GDS version 1)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis produced daily on an operational basis at Ifremer/CERSAT...

  1. GHRSST Level 4 G1SST Global Foundation Sea Surface Temperature Analysis (GDS version 1)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis produced daily on an operational basis by the JPL OurOcean...

  2. GHRSST Level 4 MW_OI Global Foundation Sea Surface Temperature analysis (GDS version 2)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) global Level 4 sea surface temperature analysis produced daily on a 0.25 degree grid at Remote Sensing...

  3. GHRSST Level 4 K10_SST Global 1 meter Sea Surface Temperature Analysis (GDS version 1)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis produced daily on an operational basis at the Naval...

  4. GHRSST Level 4 EUR Mediterranean Sea Regional Foundation Sea Surface Temperature Analysis (GDS version 2)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis produced daily by Ifremer/CERSAT (France) using optimal...

  5. GHRSST Level 4 ODYSSEA Eastern Central Pacific Regional Foundation Sea Surface Temperature Analysis (GDS version 1)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis produced daily on an operational basis at Ifremer/CERSAT...

  6. GHRSST Level 4 ODYSSEA Global Foundation Sea Surface Temperature Analysis (GDS version 1)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis produced daily on an operational basis at Ifremer/CERSAT...

  7. GHRSST Level 4 OSPO Global Foundation Sea Surface Temperature Analysis (GDS version 2)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis produced daily on an operational basis at the Office of...

  8. GHRSST Level 4 GAMSSA Global Foundation Sea Surface Temperature Analysis (GDS version 1)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis produced daily on an operational basis at the Australian Bureau...

  9. GHRSST Level 4 RAMSSA Australian Regional Foundation Sea Surface Temperature Analysis (GDS version 1)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis produced daily on an operational basis at the Australian Bureau...

  10. GHRSST Level 4 OSTIA Global Foundation Sea Surface Temperature Analysis (GDS versions 1 and 2)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis produced daily on an operational basis at the UK Met Office...

  11. Radioactivity levels in surface water of lakes around Izmir / Turkey

    International Nuclear Information System (INIS)

    Doyurum, S.; Turkozu, D. A.; Aslani, M. A. A.; Aytas, S.; Eral, M.; Kaygun, A. K.

    2006-01-01

    Radioactivity presents in surface continental waters is mainly due to the presence of radioactive elements in the earth's crust, other artificial radionuclides have appeared due to such human activities as nuclear power plants, nuclear weapons testing and manufacture and use of radioactive sources It is well known that natural radionuclides can be effective as tracers for the different processes controlling the distribution of elements among dissolved and particulate phases in aquatic systems. The detection of high radionuclide concentrations was proposed as a public health problem in several areas and consequently studies into the risks of radionuclides were started in the 2000s. Especially, these radioactive substances in groundwater are an unwanted and involuntary risk factor from natural sources, not artificial sources. These radioactive substances include uranium, radon found in uranium series, and other radioactive substances such as radium and gross alpha. Uranium present in rock, soil, and natural materials, and is found in small quantities in air, water, and food that people always contact. In this project, lake water samples were collected from three lakes around Izmir-Turkey. In surface lake water samples, pH, mV and conductivity values were measured and alkaline content was determined titrimetrically. The uranium concentrations in the lake water samples were measured using uranium analyzer. The radioactivity concentrations related to gross radium isotopes, gross-? and gross-? activities in the surface lake water were determined. The correlation among some parameters for water samples and concentrations of uranium, activity concentration of gross radium isotopes, gross alpha and gross beta radioactivity are also discussed

  12. FJ-2207 measuring instrument detection pipe surface a level of pollution method

    International Nuclear Information System (INIS)

    Wang Jiangong

    2010-01-01

    On the pipe surface contamination were detected α level of pollution is a frequently encountered dose-detection work. Because the pipeline surface arc, while the measuring probe for the plane, which for accurate measurement difficult. In this paper, on the FJ-2207-type pipe surface contamination measuring instrument measuring pollution levels in the α method was studied. Introduced the FJ-2207 measuring instrument detection pipe surface α pollution levels. Studied this measuring instrument on the same sources of surface, plane α level of radioactivity measured differences in the results obtained control of the apparatus when the direct measurement of the surface correction factor, and gives 32-216 specifications commonly used pipe direct measurement of the amendment factor. Convenient method, test results are reliable for the accurate measurement of pipe pollution levels in the surface of α as a reference and learning. (authors)

  13. Surface finishing and levelling of thermomechanically hardened rolled steel

    International Nuclear Information System (INIS)

    Grosval'd, V.G.; Bashchenko, A.P.; Grishkov, A.I.; Gutnik, M.V.; Kanevskij, B.L.; Nikozov, A.I.; Sedov, N.D.; Prosin, K.A.; Safonov, L.I.

    1975-01-01

    The finishing of high-strength merchant shapes from alloy steel was tried out under industrial conditions with the equipment of metallurgical plants. After thermomechanical hardening in the production line of the rolling mill, 30KhGSN2A and 40Kh1NVA steel rounds 32 and 31 mm in diameter were straightened on a two-roller straightening machine designed by the All-Union Scientific Research Institute for Metallurgical Machinery (VNII Metmash). This made possible subsequent turning and grinding of the rods. The conditions of straightening, turning and grinding have been worked so as to obtain thermomechanically strengthened and ground rolled products approximating the gauged and ground metal in shape geometry and surface finish. It is shown that the labour-consuming operation of turning can be eliminated by reducing the machining pass of the rolled product, and this lowers the labour required for the finishing operations by 75%. After grinding with 40- and 25-grain abrasive wheels, high strength rolled shapes were obtained with a diameter of 30-0.20 mm and a surface finish of class 6-5 satisfying the technical specifications. (author)

  14. Fabrication and characterization of homogeneous surface-enhanced Raman scattering substrates by single pulse UV-laser treatment of gold and silver films.

    Science.gov (United States)

    Christou, Konstantin; Knorr, Inga; Ihlemann, Jürgen; Wackerbarth, Hainer; Beushausen, Volker

    2010-12-07

    The fabrication of SERS-active substrates, which offer high enhancement factors as well as spatially homogeneous distribution of the enhancement, plays an important role in the expansion of surface-enhanced Raman scattering (SERS) spectroscopy to a powerful, quantitative, and noninvasive measurement technique for analytical applications. In this paper, a novel method for the fabrication of SERS-active substrates by laser treatment of 20, 40, and 60 nm thick gold and of 40 nm thick silver films supported on quartz glass is presented. Single 308 nm UV-laser pulses were applied to melt the thin gold and silver films. During the cooling process of the noble metal, particles were formed. The particle size and density were imaged by atomic force microscopy. By varying the fluence, the size of the particles can be controlled. The enhancement factors of the nanostructures were determined by recording self-assembled monolayers of benzenethiol. The intensity of the SERS signal from benzenethiol is correlated to the mean particle size and thus to the fluence. Enhancement factors up to 10(6) with a high reproducibility were reached. Finally we have analyzed the temperature dependence of the SERS effect by recording the intensity of benzenethiol vibrations from 300 to 120 K. The temperature dependence of the SERS effect is discussed with regard to the metal properties.

  15. Skin Cancer and UV Protection

    Directory of Open Access Journals (Sweden)

    Tarbuk Anita

    2016-03-01

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

  16. UV laser photoactivation of hexachloroplatinate bound to individual nucleobases in vacuo as molecular level probes of a model photopharmaceutical.

    Science.gov (United States)

    Matthews, Edward; Sen, Ananya; Yoshikawa, Naruo; Bergström, Ed; Dessent, Caroline E H

    2016-06-01

    Isolated molecular clusters of adenine, cytosine, thymine and uracil bound to hexachloroplatinate, PtCl6(2-), have been studied using laser electronic photodissociation spectroscopy to investigate photoactivation of a platinum complex in the vicinity of a nucleobase. These metal complex-nucleobase clusters represent model systems for identifying the fundamental photochemical processes occurring in photodynamic platinum drug therapies that target DNA. This is the first study to explore the specific role of a strongly photoactive platinum compound in the aggregate complex. Each of the clusters studied displays a broadly similar absorption spectra, with a strong λmax ∼ 4.6 eV absorption band and a subsequent increase in the absorption intensity towards higher spectral-energy. The absorption bands are traced to ligand-to-metal-charge-transfer excitations on the PtCl6(2-) moiety within the cluster, and result in Cl(-)·nucleobase and PtCl5(-) as primary photofragments. These results demonstrate how selective photoexcitation can drive distinctive photodecay channels for a model photo-pharmaceutical. In addition, cluster absorption due to excitation of nucleobase-centred chromophores is observed in the region around 5 eV. For the uracil cluster, photofragments consistent with ultrafast decay of the excited state and vibrational predissociation on the ground-state surface are observed. However, this decay channel becomes successively weaker on going from thymine to cytosine to adenine, due to differential coupling of the excited states to the electron detachment continuum. These effects demonstrate the distinctive photophysical characteristics of the different nucleobases, and are discussed in the context of the recently recorded photoelectron spectra of theses clusters.

  17. Laser surface processing with controlled nitrogen-argon concentration levels for regulated surface life time

    Science.gov (United States)

    Obeidi, M. Ahmed; McCarthy, E.; Brabazon, D.

    2018-03-01

    Laser surface modification can be used to enhance the mechanical properties of a material, such as hardness, toughness, fatigue strength, and corrosion resistance. Surface nitriding is a widely used thermochemical method of surface modification, in which nitrogen is introduced into a metal or other material at an elevated temperature within a furnace. It is used on parts where there is a need for increased wear resistance, corrosion resistance, fatigue life, and hardness. Laser nitriding is a novel method of nitriding where the surface is heated locally by a laser, either in an atmosphere of nitrogen or with a jet of nitrogen delivered to the laser heated site. It combines the benefits of laser modification with those of nitriding. Recent work on high toughness tool steel samples has shown promising results due to the increased nitrogen gas impingement onto the laser heated region. Increased surface activity and nitrogen adsorption was achieved which resulted in a deeper and harder surface compared to conventional hardening methods. In this work, the effects of the laser power, pulse repetition frequency, and overlap percentage on laser surface treatment of 316 L SST steel samples with an argon-nitrogen jet will be presented. Resulting microstructure, phase type, microhardness, and wear resistance are presented.

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

    Science.gov (United States)

    Gomes, L. M.; Ventura, L.

    2018-02-01

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

  19. Oxidative damage in response to natural levels of UV-B radiation in larvae of the tropical sea urchin Tripneustes gratilla.

    Science.gov (United States)

    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.

  20. A comparative study of the disinfection efficacy of H2O2/ferrate and UV/H2O2/ferrate processes on inactivation of Bacillus subtilis spores by response surface methodology for modeling and optimization.

    Science.gov (United States)

    Matin, Atiyeh Rajabi; Yousefzadeh, Samira; Ahmadi, Ehsan; Mahvi, Amirhossein; Alimohammadi, Mahmood; Aslani, Hassan; Nabizadeh, Ramin

    2018-04-03

    Although chlorination can inactivate most of the microorganisms in water but protozoan parasites like C. parvum oocysts and Giardia cysts can resist against it. Therefore, many researches have been conducted to find a novel method for water disinfection. Present study evaluated the synergistic effect of H2O2 and ferrate followed by UV radiation to inactivate Bacillus subtilis spores as surrogate microorganisms. Response surface methodology(RSM) was employed for the optimization for UV/H2O2/ferrate and H2O2/ferrate processes. By using central composite design(CCD), the effect of three main parameters including time, hydrogen peroxide, and ferrate concentrations was examined on process performance. The results showed that the combination of UV, H2O2 and ferrate was the most effective disinfection process in compare with when H2O2 and ferrate were used. This study indicated that by UV/H2O2/ferrate, about 5.2 log reductions of B. subtilis spores was inactivated at 9299 mg/l of H2O2 and 0.4 mg/l of ferrate concentrations after 57 min of contact time which was the optimum condition, but H2O2/ferrate can inactivate B. subtilis spores about 4.7 logs compare to the other process. Therefore, the results of this research demonstrated that UV/H2O2 /ferrate process is a promising process for spore inactivation and water disinfection. Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. Effects of UV-B radiation on wax biosynthesis

    International Nuclear Information System (INIS)

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

    1994-01-01

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

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

    Science.gov (United States)

    Popov, Dmitri; Jones, Jeffrey; Maliev, Slava

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

  3. UV radiation and its effects. Proceedings

    International Nuclear Information System (INIS)

    1993-01-01

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

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

    Science.gov (United States)

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

    2018-06-01

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

  5. UV-associated decline in systemic folate: implications for human nutrigenetics, health, and evolutionary processes.

    Science.gov (United States)

    Lucock, Mark; Beckett, Emma; Martin, Charlotte; Jones, Patrice; Furst, John; Yates, Zoe; Jablonski, Nina G; Chaplin, George; Veysey, Martin

    2017-03-01

    The purpose of this study was to examine whether UV exposure alters folate status according to C677T-MTHFR genotype, and to consider the relevance of this to human health and the evolutionary model of skin pigmentation. Total Ozone Mapping Spectrometer (TOMS) satellite data were used to examine surface UV-irradiance, as a marker of UV exposure, in a large (n = 649) Australian cross-sectional study population. PCR/RFLP analysis was used to genotype C677T-MTHFR. Overall, cumulative UV-irradiance (42 and 120 days pre-clinic) was significantly negatively related to red cell folate (RCF) levels. When the cohort was stratified by MTHFR-C677T genotype, the relationship between UV-irradiance (42 days pre-clinic) and RCF remained significant only in the cohorts containing carriers of the T allele. Statistically significant z-score statistics and interaction terms from genotype and UV-irradiance (p-interaction) demonstrated that genotype did modify the effect of UV-irradiance on RCF, with the largest effect of UV being demonstrated in the 677TT-MTHFR subjects. Data provide strong evidence that surface UV-irradiance reduces long-term systemic folate levels, and that this is influenced by the C677T-MTHFR gene variant. We speculate this effect may be due to 677TT-MTHFR individuals containing more 5,10CH 2 -H 4 PteGlu, and that this folate form may be particularly UV labile. Since UV-irradiance lowers RCF in an MTHFR genotype-specific way, there are likely implications for human health and the evolution of skin pigmentation. © 2016 Wiley Periodicals, Inc.

  6. [Dot1 and Set2 Histone Methylases Control the Spontaneous and UV-Induced Mutagenesis Levels in the Saccharomyces cerevisiae Yeasts].

    Science.gov (United States)

    Kozhina, T N; Evstiukhina, T A; Peshekhonov, V T; Chernenkov, A Yu; Korolev, V G

    2016-03-01

    In the Saccharomyces cerevisiae yeasts, the DOT1 gene product provides methylation of lysine 79 (K79) of hi- stone H3 and the SET2 gene product provides the methylation of lysine 36 (K36) of the same histone. We determined that the dot1 and set2 mutants suppress the UV-induced mutagenesis to an equally high degree. The dot1 mutation demonstrated statistically higher sensitivity to the low doses of MMC than the wild type strain. The analysis of the interaction between the dot1 and rad52 mutations revealed a considerable level of spontaneous cell death in the double dot1 rad52 mutant. We observed strong suppression of the gamma-in- duced mutagenesis in the set2 mutant. We determined that the dot1 and set2 mutations decrease the sponta- neous mutagenesis rate in both single and d ouble mutants. The epistatic interaction between the dot1 and set2 mutations and almost similar sensitivity of the corresponding mutants to the different types of DNA damage allow one to conclude that both genes are involved in the control of the same DNA repair pathways, the ho- mologous-recombination-based and the postreplicative DNA repair.

  7. A depleted ozone layer absorbs less UV-B, cooling the ozone layer, increasing the amount of UV-B observed to reach Earth, heating air by dissociating tropospheric and ground-level ozone, and heating oceans very efficiently by penetrating tens of meters into the mixed layer. UV-B is 48 times more energetic ("hotter") than IR absorbed by greenhouse gases

    Science.gov (United States)

    Ward, P. L.

    2017-12-01

    This new insight into the physics of radiation shows why changes in stratospheric ozone are observed to cause changes in global temperature. By 1970, manufactured CFC gases and ozone depletion began increasing. By 1993, increases in CFCs stopped as mandated by the Montreal Protocol. By 1995, increases in ozone depletion stopped. By 1998, increases in temperature stopped until 2014. Ozone is also depleted by halogen gases emitted from major basaltic lava flows, the largest of which, since 1783, occurred at Bardarbunga in Iceland in 2014, causing 2015 and 2016 to be the hottest years on record. Throughout Earth history, the largest basaltic lava flows were contemporaneous with periods of greatest warming and greatest levels of mass extinctions. Planck's empirical law shows that temperature of matter results from oscillation of all the bonds holding matter together. The higher the temperature, the higher the frequencies and amplitudes of oscillation. Thus, radiation from a nearby hotter body will make the absorbing body hotter than radiation from a cooler body. According to the Planck-Einstein relation, thermal energy (E) in matter and in radiation equals frequency of oscillation (ν) times the Planck constant (h), E=hν—the energy of a frictionless atomic oscillator. Since frequency is observed to be a very broad continuum extending from radio signals through visible light to gamma rays, thermal energy (E=hν) must also be a very broad continuum. Thermal flux cannot be represented properly by a single number of watts per square meter, as commonly assumed throughout the physical sciences, because all frequencies coexist and the number of watts increases with frequency. Thus, UV-B solar radiation is 48 times more energetic than IR terrestrial radiation absorbed by greenhouse gases and can make the absorbing body 48 times hotter. UV-B causes sunburn; no amount of IR can cause sunburn. Furthermore, in a basic experiment, I show that air containing more than 23 times

  8. Sea level and turbidity controls on mangrove soil surface elevation change

    Science.gov (United States)

    Lovelock, Catherine E.; Fernanda Adame, Maria; Bennion, Vicki; Hayes, Matthew; Reef, Ruth; Santini, Nadia; Cahoon, Donald R.

    2015-01-01

    Increases in sea level are a threat to seaward fringing mangrove forests if levels of inundation exceed the physiological tolerance of the trees; however, tidal wetlands can keep pace with sea level rise if soil surface elevations can increase at the same pace as sea level rise. Sediment accretion on the soil surface and belowground production of roots are proposed to increase with increasing sea level, enabling intertidal habitats to maintain their position relative to mean sea level, but there are few tests of these predictions in mangrove forests. Here we used variation in sea level and the availability of sediments caused by seasonal and inter-annual variation in the intensity of La Nina-El Nino to assess the effects of increasing sea level on surface elevation gains and contributing processes (accretion on the surface, subsidence and root growth) in mangrove forests. We found that soil surface elevation increased with mean sea level (which varied over 250 mm during the study) and with turbidity at sites where fine sediment in the water column is abundant. In contrast, where sediments were sandy, rates of surface elevation gain were high, but not significantly related to variation in turbidity, and were likely to be influenced by other factors that deliver sand to the mangrove forest. Root growth was not linked to soil surface elevation gains, although it was associated with reduced shallow subsidence, and therefore may contribute to the capacity of mangroves to keep pace with sea level rise. Our results indicate both surface (sedimentation) and subsurface (root growth) processes can influence mangrove capacity to keep pace with sea level rise within the same geographic location, and that current models of tidal marsh responses to sea level rise capture the major feature of the response of mangroves where fine, but not coarse, sediments are abundant.

  9. Assessment of surface contamination level in an operating uranium ore processing facility of Jaduguda, India

    International Nuclear Information System (INIS)

    Meena, J.S.; Patnaik, R.L.; Jha, V.N.; Sahoo, S.K.; Ravi, P.M.; Tripathi, R.M.

    2014-01-01

    Radiological concern of the occupational workers and the area is given priority over other safety issue in confirmation with the stipulated guideline of national regulatory agency (AERB/FEFCF/SG-2, 2007). The key concern from the radiological hazard evaluation point of view is air activity, external gamma level and surface contamination. Present investigations was carried out to ascertain the surface contamination level of uranium ore processing facility at Jaduguda, Jharkhand. For a low grade uranium ore processing industry surface contamination is a major concern in product precipitation and recovery section. In view of this, the ore processing plant can broadly be classified into three areas i.e. ion exchange area, precipitation and product recovery section and other areas. The monitoring results incorporate the level of surface contamination of the plant during the last five years. The geometric mean activity of surface contamination level was 31.1, 34.5 and 9.8 Bq dm -2 in ion exchange, product precipitation and recovery and other areas with GSD of 2, 2.5 and 1.9. In most of the cases the surface contamination level was well within the recommended limit of 100 Bq dm -2 for M class uranium compound. Occasional cases of surface contamination levels exceeding the recommended limit were addressed and areas were decontaminated. Based on the study, modification in the design feature of the surface of the finished product section was also suggested so that the decontamination procedure can be more effectively implemented

  10. Waterborne UV coating for industrial applications

    International Nuclear Information System (INIS)

    Bhattacharya, I.N.

    2007-01-01

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

  11. Sustained Increase of 25-Hydroxyvitamin D Levels in Healthy Young Women during Wintertime after Three Suberythemal UV Irradiations-The MUVY Pilot Study.

    Directory of Open Access Journals (Sweden)

    Maria Gudrun Biersack

    Full Text Available Vitamin D (VitD deficiency is a health problem prevalent not only in the elderly but also in young adults. The primary objective of our observational pilot study "MUVY" (Mood, UVR, Vitamin D in Young women was to test both the short-term and long-term effects of a series of three suberythemal UV radiation (UVR exposures on the VitD status and well-being of young healthy women during winter in a repeat measure design.20 healthy young women (Fitzpatrick skin types I-III, aged 21-25 years received three full body broad band UVR exposures with an escalating erythemally weighted dose schedule during one week in winter, and completed self-report questionnaires monitoring symptoms of depression (Beck Depression Inventory, BDI and affective state/well-being (Profile of Mood States, POMS at baseline and three days after the last UVR exposure. 25-hydroxyvitamin D (25(OHD and 1,25-dihydroxyvitamin D (1,25(OH2D were measured in serum at baseline, and at study days 8, 36 and 50.Mean baseline 25(OHD level was 54.3 nmol/L (standard deviation (s.d. = 24.1, with seven women having VitD deficient status. Relevant symptoms of depression, as indicated by low BDI total scores (0-8, were absent. After the three UVR exposures the increment of 25(OHD was an average of 13.9 nmol/L (95% confidence interval (CI = 9.4-18.4 and 26.2 pmol/L (95%CI = 7.2-45.1 for 1,25(OH2D. Δ25(OHD, and corresponding baseline levels were significantly and inversely associated (rho = -0.493, p = 0.027. Only 25(OHD remained significantly increased above baseline for at least six weeks after the last UVR exposure. A strong inverse correlation of the POMS subscale "Vigor/Activity" and the increment in 1,25(OH2D was found (rho = -0.739, p<0.001 at day 8.Three suberythemal whole body UVR exposures during one week are a simple and suitable method for improving 25(OHD levels during winter, for at least six weeks, and especially in young women with VitD deficient status.German Clinical Trials

  12. Electron mobility on the surface of liquid Helium: influence of surface level atoms and depopulation of lowest subbands

    International Nuclear Information System (INIS)

    Grigoriev, P. D.; Dyugaev, A. M.; Lebedeva, E. V.

    2008-01-01

    The temperature dependence of electron mobility is examined. We calculate the contribution to the electron scattering rate from the surface level atoms (SLAs), proposed in [10]. This contribution is substantial at low temperatures T < 0.5, when the He vapor concentration is exponentially small. We also study the effect of depopulation of the lowest energy subband, which leads to an increase in the electron mobility at high temperature. The results explain certain long-standing discrepancies between the existing theory and experiment on electron mobility on the surface of liquid helium

  13. Levels of surface contamination with radioactive materials at workplaces of nuclear research centre at Rez

    International Nuclear Information System (INIS)

    Hoelgye, Z.; Nemcova, I.; Kasikova, M.; Popper, J.; Chysky, J.

    1983-01-01

    A hygiene supervision unit at workplaces of the nuclear Research Institute in Rez monitored on a long-term basis surface contamination with radioactive substances. Surface contamination was found at workplaces with open sources. Of the 4343 monitored places action levels were only exceeded in 13 cases. The obtained data were used for typifying workplaces with the highest level of surface contamination, to determine in certain instances the mechanism of the escape of radioactive substances from insulating facilities and to determine the rate of the spread of the radioactive substance into adjacent non-active workplaces. (author)

  14. Behavior of Rydberg atoms at surfaces: energy level shifts and ionization

    Energy Technology Data Exchange (ETDEWEB)

    Dunning, F.B. E-mail: fbd@rice.edu; Dunham, H.R.; Oubre, C.; Nordlander, P

    2003-04-01

    The ionization of xenon atoms excited to the extreme red and blue states in high-lying Xe(n) Stark manifolds at a metal surface is investigated. The data show that, despite their very different initial spatial characteristics, the extreme members of a given Stark manifold ionize at similar atom/surface separations. This is explained, with the aid of complex scaling calculations, in terms of the strong perturbations in the energies and structure of the atomic states induced by the presence of the surface which lead to avoided crossings between neighboring levels as the surface is approached.

  15. Behavior of Rydberg atoms at surfaces: energy level shifts and ionization

    CERN Document Server

    Dunning, F B; Oubre, C D; Nordlander, P

    2003-01-01

    The ionization of xenon atoms excited to the extreme red and blue states in high-lying Xe(n) Stark manifolds at a metal surface is investigated. The data show that, despite their very different initial spatial characteristics, the extreme members of a given Stark manifold ionize at similar atom/surface separations. This is explained, with the aid of complex scaling calculations, in terms of the strong perturbations in the energies and structure of the atomic states induced by the presence of the surface which lead to avoided crossings between neighboring levels as the surface is approached.

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

    International Nuclear Information System (INIS)

    Boer, J.; Schothorst, A.A.; Suurmond, D.

    1981-01-01

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

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

    International Nuclear Information System (INIS)

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

    1975-01-01

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

  18. Occurrence and profiles of organic sun-blocking agents in surface waters and sediments in Japanese rivers and lakes

    International Nuclear Information System (INIS)

    Kameda, Yutaka; Kimura, Kumiko; Miyazaki, Motonobu

    2011-01-01

    Sun-blocking agents including eight UV filters (UVF) and 10 UV light stabilizers (UVLS) were measured in water and sediment collected from 22 rivers, four sewage treatment plant effluents (STPE) and three lakes in Japan. Total sun blocking agents levels ranged from N.D. to 4928 ng/L and from 2.0 to 3422 μg/kg dry wt in surface water and in sediment, respectively. Benzyl salicylate, benzophenone-3, 2-ethyl hexyl-4-methoxycinnamte (EHMC) and octyl salicylate were dominant in surface water receiving wastewater effluents and STPE, although UV-328, benzophenone and EHMC were dominant in other surface water except background sites. Three UVF and nine UVLS were observed from all sediment and their compositions showed similar patterns with UV-328 and UV-234 as the most prevalent compounds. Homosalate, octocrylene, UV-326, UV-327, UV-328 and UV-234 were significantly correlated with Galaxolide in sediments. Concentrations of UV-327 and UV-328 also had strong correlation between those of UV-326 in sediment. - Highlights: → Total sun-blocking agents levels ranged from N.D. to 4928 ng/L in surface water from 29 sampling sites. → The maximum concentration of total sun-blocking agents was 3422 μg/kg dry wt. in sediment. → Residential wastewaters and STPE were considered to be potential sources of UVLS in river and lakes. → Most of sun-blocking agents in sediment were significantly correlated with HHCB. → UV-326 had a strong linear correlation between UV-327 as well as UV-328 in all sediment. - Occurrence of eight UV filters and 10 UV light stabilizers in surface water and sediment were investigated and characterized their compositions in water and sediment.

  19. Molecular-level chemistry of model single-crystal oxide surfaces with model halogenated compounds

    Science.gov (United States)

    Adib, Kaveh

    Synchrotron-based X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption (TPD) and low energy electron diffraction (LEED) have been used to investigate, at a molecular level, the chemistry of different terminations of single crystal iron-oxide surfaces with probe molecules (CCl4 and D2O). Comparisons of the reactivity of these surfaces towards CCl4, indicate that the presence of an uncapped surface Fe cation (strong Lewis acid site) and an adjacent oxygen site capped by that cation can effect the C-Cl bond cleavage in CCl4, resulting in dissociatively adsorbed Cl-adatoms and carbon-containing fragments. If in addition to these sites, an uncapped surface oxygen (Lewis base) site is also available, the carbon-containing moiety can then move that site, coordinate itself with that uncapped oxygen, and stabilize itself. At a later step, the carbon-containing fragment may form a strong covalent bond with the uncapped oxygen and may even abstract that surface oxygen. On the other hand, if an uncapped oxygen is not available to stabilize the carbon-containing fragment, the surface coordination will not occur and upon the subsequent thermal annealing of the surface the Cl-adatoms and the carbon-containing fragments will recombine and desorb as CCl4. Finally, the presence of surface deuteroxyls blocking the strong Lewis acid and base sites of the reactive surface, passivates this surface. Such a deuteroxylated surface will be unreactive towards CCl 4. Such a molecular level understanding of the surface chemistry of metal-oxides will have applications in the areas of selective catalysis, including environmental catalysis, and chemical sensor technology.

  20. Monitoring sea level and sea surface temperature trends from ERS satellites

    DEFF Research Database (Denmark)

    Andersen, Ole Baltazar; Knudsen, Per; Beckley, B.

    2002-01-01

    Data from the two ESA satellites ERS-1 and ERS-2 are used in global and regional analysis of sea level and sea surface temperature trends over the last, 7.8 years. T he ERS satellites and in the future the ENVISAT satellite provide unique opportunity for monitoring both changes in sea level and sea...

  1. Quantum mechanical study and spectroscopic (FT-IR, FT-Raman, UV-Visible) study, potential energy surface scan, Fukui function analysis and HOMO-LUMO analysis of 3-tert-butyl-4-methoxyphenol by DFT methods.

    Science.gov (United States)

    Saravanan, S; Balachandran, V

    2014-09-15

    This study represents an integral approach towards understanding the electronic and structural aspects of 3-tert-butyl-4-methoxyphenol (TBMP). Fourier-transform Infrared (FT-IR) and Fourier-transform Raman (FT-Raman) spectra of TBMP was recorded in the region 4000-400 cm(-1) and 3500-100 cm(-1), respectively. The molecular structures, vibrational wavenumbers, infrared intensities and Raman activities were calculated using DFT (B3LYP and LSDA) methods using 6-311++G (d,p) basis set. The most stable conformer of TBMP was identified from the computational results. The assignments of vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) following the scaled quantum mechanical force field (SQMFF) methodology. The first order hyperpolarizability (β0) and related properties (β, α0 and Δα) of TBMP have been discussed. The stability and charge delocalization of the molecule was studied by Natural Bond Orbital (NBO) analysis. UV-Visible spectrum and effects of solvents have been discussed and the electronic properties such as HOMO and LUMO energies were determined by time-dependent TD-DFT approach with B3LYP/6-311++G (d,p) level of theory. The molecule orbital contributions are studied by density of energy states (DOSs). The reactivity sites are identified by mapping the electron density into electrostatic potential surface (MEP). Mulliken analysis of atomic charges is also calculated. The thermodynamic properties at different temperatures were calculated, revealing the correlations between standard heat capacities, standard entropy and standard enthalpy changes with temperatures. Global hardness, global softness, global electrophilicity and ionization potential of the title compound are determined. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Surface core level shifts of clean and oxygen covered Ir(111)

    Energy Technology Data Exchange (ETDEWEB)

    Bianchi, M; Cassese, D; Cavallin, A; Comin, R; Orlando, F; Postregna, L [Universita degli Studi di Trieste, Via A Valerio 2, 34127, Trieste (Italy); Golfetto, E; Baraldi, A [Dipartimento di Fisica e CENMAT, Universita degli Studi di Trieste, Via A Valerio 2, 34127, Trieste (Italy); Lizzit, S [Sincrotrone Trieste S.C.p.A., S.S. 14 Km 163.5, 34012 Trieste (Italy)], E-mail: alessandro.baraldi@elettra.trieste.it

    2009-06-15

    We present the results of high resolution core level photoelectron spectroscopy employed to investigate the electronic structure of clean and oxygen covered Ir(111) surface. Ir 4f{sub 7/2} core level spectra are shown to be very sensitive to the local atomic environment. For the clean surface we detected two distinct components shifted by 550 meV, originated by surface and bulk atoms. The larger Gaussian width of the bulk component is explained as due to experimentally unresolved subsurface components. In order to determine the relevance of the phonon contribution we examined the thermal behaviour of the core level lineshape using the Hedin-Rosengren theory. From the phonon-induced spectral broadening we found the Debye temperature of bulk and surface atoms to be 298 and 181 K, respectively, which confirms the softening of the vibrational modes at the surface. Oxygen adsorption leads to the appearance of new surface core level components at -200 meV and +230 meV, which are interpreted as due to first-layer Ir atoms differently coordinated with oxygen. The coverage dependence of these components demonstrates that the oxygen saturation corresponds to 0.38 ML, in good agreement with recent density functional theory calculations.

  3. Research on near-surface disposal of very low level radioactive waste

    International Nuclear Information System (INIS)

    Wang Shaowei; Yue Huiguo; Hou Jie; Chen Haiying; Zuo Rui; Wang Jinsheng

    2012-01-01

    Radioactive waste disposal is one of the most sensitive environmental problems to control and solve. As the arriving of decommissioning of early period nuclear facilities in China, large amounts of very low level radioactive waste will be produced inevitably. The domestic and abroad definitions about very low level radioactive waste and its disposal were introduced, and then siting principles of near-surface disposal of very low level radioactive waste were discussed. The near- surface disposal siting methods of very low level radioactive waste were analyzed from natural and geographical conditions assessment, geological conditions analysis, hydrogeological conditions analysis, geological hazard assessment and radioactive background investigation; the near-surface disposal sites'natural barriers of very low level radioactive waste were analyzed from the crustal structure and physico-chemical characteristics, the dynamics characteristics of groundwater, the radionuclide adsorption characteristics of natural barriers and so on; the near-surface disposal sites' engineered barriers of very low level radioactive waste were analyzed from the repository design, the repository barrier materials selection and so on. Finally, the improving direction of very low level radioactive waste disposal was proposed. (authors)

  4. Manufacturing microsystems-on-a-chip with 5-level surface micromachining technology

    Energy Technology Data Exchange (ETDEWEB)

    Sniegowski, J.; Rodgers, M.S.

    1998-05-01

    An agile microsystem manufacturing technology has been developed that provides unprecedented 5 levels of independent polysilicon surface-micromachine films for the designer. Typical surface-micromachining processes offer a maximum of 3 levels, making this the most complex surface-micromachining process technology developed to date. Leveraged from the extensive infrastructure present in the microelectronics industry, the manufacturing method of polysilicon surface-micromachining offers similar advantages of high-volume, high-reliability, and batch-fabrication to microelectromechanical systems (MEMS) as has been accomplished with integrated circuits (ICs). These systems, comprised of microscopic-sized mechanical elements, are laying the foundation for a rapidly expanding, multi-billion dollar industry 2 which impacts the automotive, consumer product, and medical industries to name only a few.

  5. Mean Annual UV-B Irradiance

    Data.gov (United States)

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

  6. An inexpensive and simple method for thermally stable immobilization of DNA on an unmodified glass surface: UV linking of poly(T)10-poly(C)10-tagged DNA probes

    DEFF Research Database (Denmark)

    Guðnason, Haukur; Dufva, Hans Martin; Bang, Dang Duong

    2008-01-01

    be linked by UV light irradiation onto a plain, unmodified glass surface. Probes immobilized onto unmodified glass microscope slides performed similarly to probes bound to commercial amino-silane-coated slides and had comparable detection limits. The TC-tagged probes linked to unmodified glass did not show...... any significant decrease in hybridization performance after a 20 min incubation in water at 100 degrees C prior to rehybridization, indicating a covalent bond between the TC tag and unmodified glass. The probes were used in thermal minisequencing cycling reactions. Furthermore, the TC tag improved...

  7. Influence of surface pre-treatment on the electronic levels in silicon MaWCE nanowires.

    Science.gov (United States)

    Venturi, Giulia; Castaldini, Antonio; Schleusener, Alexander; Sivakov, Vladimir; Cavallini, Anna

    2015-05-15

    Deep level transient spectroscopy (DLTS) was performed on n-doped silicon nanowires grown by metal-assisted wet chemical etching (MaWCE) with gold as the catalyst in order to investigate the energetic scheme inside the bandgap. To observe the possible dependence of the level scheme on the processing temperature, DLTS measurements were performed on the nanowires grown on a non-treated Au/Si surface and on a thermally pre-treated Au/Si surface. A noticeable modification of the configuration of the energy levels was observed, induced by the annealing process. Based on our results on these MaWCE nanowires and on literature data about deep levels in bulk silicon, some hypotheses were advanced regarding the identification of the defects responsible of the energy levels revealed.

  8. Room temperature, ppb-level NO2 gas sensing of multiple-networked ZnSe nanowire sensors under UV illumination

    Directory of Open Access Journals (Sweden)

    Sunghoon Park

    2014-10-01

    Full Text Available Reports of the gas sensing properties of ZnSe are few, presumably because of the decomposition and oxidation of ZnSe at high temperatures. In this study, ZnSe nanowires were synthesized by the thermal evaporation of ZnSe powders and the sensing performance of multiple-networked ZnSe nanowire sensors toward NO2 gas was examined. The results showed that ZnSe might be a promising gas sensor material if it is used at room temperature. The response of the ZnSe nanowires to 50 ppb–5 ppm NO2 at room temperature under dark and UV illumination conditions were 101–102% and 113–234%, respectively. The responses of the ZnSe nanowires to 5 ppm NO2 increased from 102 to 234% with increasing UV illumination intensity from 0 to 1.2 mW/cm2. The response of the ZnSe nanowires was stronger than or comparable to that of typical metal oxide semiconductors reported in the literature, which require higher NO2 concentrations and operate at higher temperatures. The origin of the enhanced response of the ZnSe nanowires towards NO2 under UV illumination is also discussed.

  9. Gait Characteristics Associated with Trip-Induced Falls on Level and Sloped Irregular Surfaces

    Directory of Open Access Journals (Sweden)

    Andrew Merryweather

    2011-11-01

    Full Text Available Same level falls continue to contribute to an alarming number of slip/trip/fall injuries in the mining workforce. The objective of this study was to investigate how walking on different surface types and transverse slopes influences gait parameters that may be associated with a trip event. Gait analysis was performed for ten subjects on two orientations (level and sloped on smooth, hard surface (control and irregular (gravel, larger rocks surfaces. Walking on irregular surfaces significantly increased toe clearance compared to walking on the smooth surface. There was a significant (p < 0.05 decrease in cadence (steps/min, stride length (m, and speed (m/s from control to gravel to larger rocks. Significant changes in external rotation and increased knee flexion while walking on irregular surfaces were observed. Toe and heel clearance requirements increased on irregular surfaces, which may provide an explanation for trip-induced falls; however, the gait alterations observed in the experienced workers used as subjects would likely improve stability and recovery from a trip.

  10. Probability distribution for the Gaussian curvature of the zero level surface of a random function

    Science.gov (United States)

    Hannay, J. H.

    2018-04-01

    A rather natural construction for a smooth random surface in space is the level surface of value zero, or ‘nodal’ surface f(x,y,z)  =  0, of a (real) random function f; the interface between positive and negative regions of the function. A physically significant local attribute at a point of a curved surface is its Gaussian curvature (the product of its principal curvatures) because, when integrated over the surface it gives the Euler characteristic. Here the probability distribution for the Gaussian curvature at a random point on the nodal surface f  =  0 is calculated for a statistically homogeneous (‘stationary’) and isotropic zero mean Gaussian random function f. Capitalizing on the isotropy, a ‘fixer’ device for axes supplies the probability distribution directly as a multiple integral. Its evaluation yields an explicit algebraic function with a simple average. Indeed, this average Gaussian curvature has long been known. For a non-zero level surface instead of the nodal one, the probability distribution is not fully tractable, but is supplied as an integral expression.

  11. UV disinfection in drinking water supplies.

    Science.gov (United States)

    Hoyer, O

    2000-01-01

    UV disinfection has become a practical and safely validatable disinfection procedure by specifying the requirements for testing and monitoring in DVGW standard W 294. A standardized biodosimetric testing procedure and monitoring with standardized UV sensors is introduced and successfully applied. On-line monitoring of irradiance can be counterchecked with handheld reference sensors and makes it possible that UV systems can be used for drinking water disinfection with the same level of confidence and safety as is conventional chemical disinfection.

  12. Correlation of Cell Surface Biomarker Expression Levels with Adhesion Contact Angle Measured by Lateral Microscopy.

    Science.gov (United States)

    Walz, Jenna A; Mace, Charles R

    2018-06-05

    Immunophenotyping is typically achieved using flow cytometry, but any influence a biomarker may have on adhesion or surface recognition cannot be determined concurrently. In this manuscript, we demonstrate the utility of lateral microscopy for correlating cell surface biomarker expression levels with quantitative descriptions of cell morphology. With our imaging system, we observed single cells from two T cell lines and two B cell lines adhere to antibody-coated substrates and quantified this adhesion using contact angle measurements. We found that SUP-T1 and CEM CD4+ cells, both of which express similar levels of CD4, experienced average changes in contact angle that were not statistically different from one another on surfaces coated in anti-CD4. However, MAVER-1 and BJAB K20 cells, both of which express different levels of CD20, underwent average changes in contact angle that were significantly different from one another on surfaces coated in anti-CD20. Our results indicate that changes in cell contact angles on antibody-coated substrates reflect the expression levels of corresponding antigens on the surfaces of cells as determined by flow cytometry. Our lateral microscopy approach offers a more reproducible and quantitative alternative to evaluate adhesion compared to commonly used wash assays and can be extended to many additional immunophenotyping applications to identify cells of interest within heterogeneous populations.

  13. Spatially-varying surface roughness and ground-level air quality in an operational dispersion model

    International Nuclear Information System (INIS)

    Barnes, M.J.; Brade, T.K.; MacKenzie, A.R.; Whyatt, J.D.; Carruthers, D.J.; Stocker, J.; Cai, X.; Hewitt, C.N.

    2014-01-01

    Urban form controls the overall aerodynamic roughness of a city, and hence plays a significant role in how air flow interacts with the urban landscape. This paper reports improved model performance resulting from the introduction of variable surface roughness in the operational air-quality model ADMS-Urban (v3.1). We then assess to what extent pollutant concentrations can be reduced solely through local reductions in roughness. The model results suggest that reducing surface roughness in a city centre can increase ground-level pollutant concentrations, both locally in the area of reduced roughness and downwind of that area. The unexpected simulation of increased ground-level pollutant concentrations implies that this type of modelling should be used with caution for urban planning and design studies looking at ventilation of pollution. We expect the results from this study to be relevant for all atmospheric dispersion models with urban-surface parameterisations based on roughness. -- Highlights: • Spatially variable roughness improved performance of an operational model. • Scenario modelling explored effect of reduced roughness on air pollution. • Reducing surface roughness can increase modelled ground-level pollution. • Damped vertical mixing outweighs increased horizontal advection in model study. • Result should hold for any model with a land-surface coupling based on roughness. -- Spatially varying roughness improves model simulations of urban air pollutant dispersion. Reducing roughness does not always decrease ground-level pollution concentrations

  14. Long-term variations of the UV-B radiation over Central Europe as derived from the reconstructed UV time series

    Directory of Open Access Journals (Sweden)

    J. W. Krzyscin

    2004-04-01

    Full Text Available The daily doses of the erythemally weighted UV radiation are reconstructed for three sites in Central Europe: Belsk-Poland (1966–2001, Hradec Kralove-Czech Republic (1964–2001, and Tõravere-Estonia (1967–2001 to discuss the UV climatology and the long-term changes of the UV-B radiation since the mid 1960s. Various reconstruction models are examined: a purely statistical model based on the Multivariate Adaptive Regression Splines (MARS methodology, and a hybrid model combining radiative transfer model calculations with empirical estimates of the cloud effects on the UV radiation. Modeled long-term variations of the surface UV doses appear to be in a reasonable agreement with the observed ones. A simple quality control procedure is proposed to check the homogeneity of the biometer and pyranometer data. The models are verified using the results of UV observations carried out at Belsk since 1976. MARS provides the best estimates of the UV doses, giving a mean difference between the modeled and observed monthly means equal to 0.6±2.5%. The basic findings are: similar climatological forcing by clouds for all considered stations (~30% reduction in the surface UV, long-term variations in UV monthly doses having the same temporal pattern for all stations with extreme low monthly values (~5% below overall mean level at the end of the 1970s and extreme high monthly values (~5% above overall mean level in the mid 1990s, regional peculiarities in the cloud long-term forcing sometimes leading to extended periods with elevated UV doses, recent stabilization of the ozone induced UV long-term changes being a response to a trendless tendency of total ozone since the mid 1990s. In the case of the slowdown of the total ozone trend over Northern Hemisphere mid-latitudes it seems that clouds will appear as the most important modulator of the UV radiation both in long- and short-time scales over next decades. Key words. Atmospheric composition and structure

  15. Long-term variations of the UV-B radiation over Central Europe as derived from the reconstructed UV time series

    Directory of Open Access Journals (Sweden)

    J. W. Krzyscin

    2004-04-01

    Full Text Available The daily doses of the erythemally weighted UV radiation are reconstructed for three sites in Central Europe: Belsk-Poland (1966–2001, Hradec Kralove-Czech Republic (1964–2001, and Tõravere-Estonia (1967–2001 to discuss the UV climatology and the long-term changes of the UV-B radiation since the mid 1960s. Various reconstruction models are examined: a purely statistical model based on the Multivariate Adaptive Regression Splines (MARS methodology, and a hybrid model combining radiative transfer model calculations with empirical estimates of the cloud effects on the UV radiation. Modeled long-term variations of the surface UV doses appear to be in a reasonable agreement with the observed ones. A simple quality control procedure is proposed to check the homogeneity of the biometer and pyranometer data. The models are verified using the results of UV observations carried out at Belsk since 1976. MARS provides the best estimates of the UV doses, giving a mean difference between the modeled and observed monthly means equal to 0.6±2.5%. The basic findings are: similar climatological forcing by clouds for all considered stations (~30% reduction in the surface UV, long-term variations in UV monthly doses having the same temporal pattern for all stations with extreme low monthly values (~5% below overall mean level at the end of the 1970s and extreme high monthly values (~5% above overall mean level in the mid 1990s, regional peculiarities in the cloud long-term forcing sometimes leading to extended periods with elevated UV doses, recent stabilization of the ozone induced UV long-term changes being a response to a trendless tendency of total ozone since the mid 1990s. In the case of the slowdown of the total ozone trend over Northern Hemisphere mid-latitudes it seems that clouds will appear as the most important modulator of the UV radiation both in long- and short-time scales over next decades.

    Key words. Atmospheric composition and

  16. A statistical method to get surface level air-temperature from satellite observations of precipitable water

    Digital Repository Service at National Institute of Oceanography (India)

    Pankajakshan, T.; Shikauchi, A; Sugimori, Y.; Kubota, M.

    -T a and precipitable water. The rms errors of the SSMI-T a , in this case are found to be reduced to 1.0°C. 1. Introduction Satellite derived surface-level meteorological parameters are considered to be a better alternative to sparse ship... Vol. 49, pp. 551 to 558. 1993 A Statistical Method to Get Surface Level Air-Temperature from Satellite Observations of Precipitable Water PANKAJAKSHAN THADATHIL*, AKIRA SHIKAUCHI, YASUHIRO SUGIMORI and MASAHISA KUBOTA School of Marine Science...

  17. Atomic-level spatial distributions of dopants on silicon surfaces: toward a microscopic understanding of surface chemical reactivity

    Science.gov (United States)

    Hamers, Robert J.; Wang, Yajun; Shan, Jun

    1996-11-01

    We have investigated the interaction of phosphine (PH 3) and diborane (B 2H 6) with the Si(001) surface using scanning tunneling microscopy, infrared spectroscopy, and ab initio molecular orbital calculations. Experiment and theory show that the formation of PSi heterodimers is energetically favorable compared with formation of PP dimers. The stability of the heterodimers arises from a large strain energy associated with formation of PP dimers. At moderate P coverages, the formation of PSi heterodimers leaves the surface with few locations where there are two adjacent reactive sites. This in turn modifies the chemical reactivity toward species such as PH 3, which require only one site to adsorb but require two adjacent sites to dissociate. Boron on Si(001) strongly segregates into localized regions of high boron concentration, separated by large regions of clean Si. This leads to a spatially-modulated chemical reactivity which during subsequent growth by chemical vapor deposition (CVD) leads to formation of a rough surface. The implications of the atomic-level spatial distribution of dopants on the rates and mechanisms of CVD growth processes are discussed.

  18. Statistical analysis of global surface air temperature and sea level using cointegration methods

    DEFF Research Database (Denmark)

    Schmith, Torben; Johansen, Søren; Thejll, Peter

    Global sea levels are rising which is widely understood as a consequence of thermal expansion and melting of glaciers and land-based ice caps. Due to physically-based models being unable to simulate observed sea level trends, semi-empirical models have been applied as an alternative for projecting...... of future sea levels. There is in this, however, potential pitfalls due to the trending nature of the time series. We apply a statistical method called cointegration analysis to observed global sea level and surface air temperature, capable of handling such peculiarities. We find a relationship between sea...... level and temperature and find that temperature causally depends on the sea level, which can be understood as a consequence of the large heat capacity of the ocean. We further find that the warming episode in the 1940s is exceptional in the sense that sea level and warming deviates from the expected...

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

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  20. Índice UV

    Science.gov (United States)

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

  1. uv dye lasers

    International Nuclear Information System (INIS)

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

    1975-01-01

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

  2. The need for national diagnostic reference levels: entrance surface dose measurement in intraoral radiography

    International Nuclear Information System (INIS)

    Mortazavi, S. M. J.; Shareghi, A.; Kavousi, A.; Ghiassi-Nejad, M.; Jafari-Zadeh, M.; Nazeri, F.; Mozdarani, H.

    2004-01-01

    Background: Intraoral radiographies are the most frequent X-ray examinations in humans. According to International Commission on Radiation Protection recommendations, the selection of a diagnostic reference level should be specific to a country or region. Critical organs such as thyroid gland are exposed to X-rays in intraoral radiography and these exposures should be kept as low as reasonably achievable. To assist the development of DRLs for intraoral radiography, a National Radiation Protection Department-sponsored pilot study was carried out. Materials and methods: thermoluminescent dosimetry is widely acknowledged to be the recommended method for measuring entrance surface doses. In this study, entrance surface doses was measured using LiF thermoluminescent dosimeters on the skin (either mandibular or maxillary arcs) of 40 patients. Three thermoluminescent dosimetry chips were placed on the skin of each patient. The doses were averaged for each radiography and mean entrance surface doses of all patients calculated. Results: the mean ±SD entrance surface dose at the center of the beam on the patient's skin in intraoral radiography was 1.173 ±0.606 mGy (ranged from 0.01 o 0.40 m Gy). The mean entrance surface doses for male and female patients were 1.380± 0.823, and 1.004± 0.258 respectively. No statistically significant difference was found between these means. Despite its necessity , in national level , there is no published data on the diagnostic reference levels for intraoral radiography. However, the results obtained in this study are lower than those reported by investigators in other countries. Conclusion: in IR Iran , due to lack of large scale studies, no diagnostic reference levels have been set for X-ray diagnostic procedures. Due to lack of national diagnostic reference levels, it is not possible to clarify whether in intraoral radiographies any dose reduction techniques are needed. We intend to perform similar nationwide studies to set the

  3. Calculation of reasonable exemption levels for surface contamination by measuring overall gamma ray

    International Nuclear Information System (INIS)

    Ogino, Haruyuki; Hattori, Takatoshi

    2008-01-01

    The present regulation on surface contamination [Bq/cm 2 ] is determined from a simple radiological model for the most hazardous radionuclides (Pu-239 for alpha emitters and Sr-90 for beta emitters) and its extremely conservative model is applied for all other alpha and beta emitters. In this study, reasonable exemption levels for surface contamination are calculated for each radionuclide by adopting an original radiological dose evaluation method for surface contamination that can be applied in radiation safety, transport safety and waste safety. Furthermore, a new concept of judging the exemption by estimating the overall contamination [Bq] on the objects from the measurement of gamma ray has been designed and a reasonable value was derived. We conclude that the overall exemption levels obtained by gamma ray measurement can be one order smaller than those obtained by the conventional method for some radionuclides, such as Mn-54, Co-60, Nb-94, Cs-134, Cs-137, Eu-152 and Eu-154. (author)

  4. Alkyl-terminated Si(111) surfaces: A high-resolution, core level photoelectron spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Terry, J.; Linford, M.R.; Wigren, C.; Cao, R.; Pianetta, P.; Chidsey, C.E. [Stanford University, Stanford, California 94309 (United States)

    1999-01-01

    The bonding of alkyl monolayers to Si(111) surfaces has been studied with high-resolution core level photoelectron spectroscopy (PES). Two very different wet-chemical methods have been used to prepare the alkyl monolayers: (i) Olefin insertion into the H{endash}Si bond of the H{endash}Si(111) surface, and (ii) replacement of Cl on the Cl{endash}Si(111) surface by an alkyl group from an alkyllithium reagent. In both cases, PES has revealed a C 1s component shifted to lower binding energy and a Si 2p component shifted to higher binding energy. Both components are attributed to the presence of a C{endash}Si bond at the interface. Along with photoelectron diffraction data [Appl. Phys. Lett. {bold 71}, 1056, (1997)], these data are used to show that these two synthetic methods can be used to functionalize the Si(111) surface. {copyright} {ital 1999 American Institute of Physics.}

  5. The impact of accelerometer mounting methods on the level of vibrations recorded at ground surface

    Directory of Open Access Journals (Sweden)

    Krzysztof Czech

    2014-08-01

    Full Text Available The paper presents the results of field research based on the measurements of accelerations recorded at ground surface. The source of the vibration characterized by high repetition rate of pulse parameters was light falling weight deflectometer ZFG-01. Measurements of vibrations have been carried out using top quality high-precision measuring system produced by Brüel&Kiær. Accelerometers were mounted on a sandy soil surface at the measuring points located radially at 5-m and 10-m distances from the source of vibration. The paper analyses the impact that the method of mounting accelerometers on the ground has on the level of the recorded values of accelerations of vibrations. It has been shown that the method of attaching the sensor to the surface of the ground is crucial for the credibility of the performed measurements.[b]Keywords[/b]: geotechnics, surface vibrations, ground, vibration measurement

  6. Monitoring the variability of sea level and surface circulation with satellite altimetry

    NARCIS (Netherlands)

    Volkov, Denis L. "Jr"

    2004-01-01

    Variability in the ocean plays an important role in determining global weather and climate conditions. The advent of satellite altimetry has significantly facilitated the study of the variability of sea level and surface circulation. Satellites provide high-quality regular and nearly global

  7. Deep layer-resolved core-level shifts in the beryllium surface

    DEFF Research Database (Denmark)

    Aldén, Magnus; Skriver, Hans Lomholt; Johansson, Börje

    1993-01-01

    Core-level energy shifts for the beryllium surface region are calculated by means of a Green’s function technique within the tight-binding linear muffin-tin orbitals method. Both initial- and final-state effects in the core-ionization process are fully accounted for. Anomalously large energy shifts...

  8. Levels of Cd, Hg and Zn in some surface waters from the Eastern ...

    African Journals Online (AJOL)

    Total trace metals levels - Cd, Hg and Zn, which may affect human health and the "health" of the aquatic ecosystem, were determined in the Umtata, Buffalo, Keiskamma and Tyume Rivers and in the Sandile and Umtata Dams. These elements were also determined in sediment samples from some of these surface waters.

  9. L’utilisation d’adhésifs optiques réticulables aux UV pour le collage d’objets d’art en verre transparent coloré, à surface d’encollage réduite

    Directory of Open Access Journals (Sweden)

    Viviane Bechoux

    2011-11-01

    Full Text Available La recherche porte sur une double problématique :1° La possibilité d’utiliser les adhésifs réticulables aux UV  pour coller le verre transparent coloré. 2° Le collage du verre  s’avère très complexe quand les éléments à assembler sont fins, fragiles et quand la surface d’encollage est réduite à quelques millimètres.Dans ce cas précis, la solidité mécanique du collage et la rapidité de polymérisation de l’adhésif sont les premiers critères à prendre en compte pour assurer un assemblage final fiable.This research focuses on two issues : 1° The possibility to use UV-crosslinkable adhesives to bond transparent coloured glass.2° The glass bonding is very complex when the parts to be joined are thin, fragile, and when the bonding surface is reduced to a few millimetres in size. In this case, the mechanical strength of the bonding and the speed of the curing process of the adhesive are the first criteria to be taken into account to ensure a reliable final bonding.

  10. Statistical analysis of global surface temperature and sea level using cointegration methods

    DEFF Research Database (Denmark)

    Schmidt, Torben; Johansen, Søren; Thejll, Peter

    2012-01-01

    Global sea levels are rising which is widely understood as a consequence of thermal expansion and melting of glaciers and land-based ice caps. Due to the lack of representation of ice-sheet dynamics in present-day physically-based climate models being unable to simulate observed sea level trends......, semi-empirical models have been applied as an alternative for projecting of future sea levels. There is in this, however, potential pitfalls due to the trending nature of the time series. We apply a statistical method called cointegration analysis to observed global sea level and land-ocean surface air...... temperature, capable of handling such peculiarities. We find a relationship between sea level and temperature and find that temperature causally depends on the sea level, which can be understood as a consequence of the large heat capacity of the ocean. We further find that the warming episode in the 1940s...

  11. Serum levels of vitamin A, visual function and ocular surface after bariatric surgery

    Directory of Open Access Journals (Sweden)

    Luana Paula Nogueira de Araújo BRANDÃO

    Full Text Available ABSTRACT BACKGROUND Bariatric surgery is the most effective treatment for severe obesity, but the surgery increases the risk of developing nutritional deficiencies, such as vitamin A deficiency. In human metabolism, vitamin A plays a role in vision. OBJECTIVE To evaluate serum vitamin A, visual function and ocular surface of patients undergoing bariatric surgery. METHODS A cross-sectional and analytical study was conduced with 28 patients undergoing bariatric surgery for at least 6 months. Ophthalmologic evaluation was done through color vision test, contrast sensitivity test, ocular surface tests and confocal microscopy, as well as vitamin A serum measurement. RESULTS Vertical sleeve gastrectomy was performed in seven (25.0% patients and Roux -en-Y gastric by-pass in 21 (75.0%. Mean serum vitamin A level was 1.7±0.5 µmoL/L. Most patients (60.7% had symptoms of dry eye. Five (17.9% patients had contrast sensitivity impairment and 18 (64.3% color vision changes. In the group of patients undergoing Roux -en-Y gastric by-pass , mean vitamin A levels were 1.8±0.6 µmoL/L, whereas they were 1.7±0.5 µmoL/L in patients submitted to the restrictive technique vertical sleeve gastrectomy . The analysis of the influence of serum levels of vitamin A in the visual function and ocular surface was performed by Pearson correlation test and there was no significant correlation between any of the variables and vitamin A. CONCLUSION There was no influence of the bariatric surgery technique used on serum vitamin A levels, on the visual function or on the ocular surface. Moreover, there was no correlation between serum levels of vitamin A and the visual function or the ocular surface changes.

  12. Climatology of surface ultraviolet-radiation in Valparaiso, Chile

    International Nuclear Information System (INIS)

    Cordero, Raul R.; Roth, Pedro; Georgiev, Aleksandar; Silva, Luis da

    2005-01-01

    Despite the lack of long-term records, it is possible to describe many of the short term characteristics, dependencies and climatology of surface UV irradiance. This paper describes the climatology of on ground UV irradiance at Valparaiso (33.05 deg. S, 71.63 deg. W, sea level), Chile. The dependence of UV-B irradiance on ozone and on other climate variables is discussed with reference to our observations conducted during the last four years. Special attention was paid to detect 'ozone events' by surface UV irradiance measurements. By analyzing time series of the UV-B/UV-A ratio, we suppressed the cloud variability effect and detected events that implied ozone column changes of about 15%. According to our measurements, during the last four years, the ozone column over Valparaiso was not affected negatively by the Antarctic ozone hole phenomenon

  13. UV-Induced Cell Death in Plants

    Science.gov (United States)

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

    2013-01-01

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

  14. Preferences of lame cows for type of surface and level of social contact in hospital pens

    DEFF Research Database (Denmark)

    Jensen, Margit Bak; Herskin, Mette S; Thomsen, Peter T.

    2015-01-01

    To investigate preferences of lame cows for flooring and level of social contact, 37 lame, lactating dairy cows (diagnosed with sole ulcer or white line disease) were housed individually for 6 d in experimental hospital pens, where they could choose between 2 equally sized areas (6m × 4.5m......) with either deep-bedded sand or a rubber surface. On both surfaces, cows could choose between 2 equally sized areas either near or away from heifers in a neighboring group pen. Cows spent more time lying on the deep-bedded sand than on the rubber surface (870 vs. 71min/d), whereas they spent less time upright...... (standing or walking) on the sand than on the rubber surface (180 vs. 319min/d). In addition, cows spent less time self-grooming on the sand than on the rubber surface (2.2 vs. 4.7% of time spent upright). With regard to level of social contact, cows spent more time near the neighboring heifers than away...

  15. Severity of MIH findings at tooth surface level among German school children.

    Science.gov (United States)

    Petrou, M A; Giraki, M; Bissar, A-R; Wempe, C; Schäfer, M; Schiffner, U; Beikler, T; Schulte, A G; Splieth, C H

    2015-06-01

    This study was to investigate the distribution and clinical characteristics of teeth diagnosed with MIH at surface and defect type level in a cohort of German children. The study cohort included 242 children diagnosed with MIH which had been recorded during the compulsory dental school examinations of 20 German primary schools. The subjects had been enrolled by cluster sampling. All children attended the second to fourth grade (age 7-10 years, mean 8.1 ± 0.8). The children were examined by five calibrated examiners (kappa = 0.9) after tooth brushing. The recording comprised teeth, surfaces, type and severity of MIH defects and was conducted using a portable light, mirrors and cotton rolls. MIH was registered according to the EAPD criteria. Defects MIH defects at various surfaces of the same tooth were common. The number of affected tooth surfaces was positively correlated with the severity of MIH at child (p MIH teeth. The knowledge of the intra-oral distribution and severity of MIH findings at the enamel surface level is important for assessing the treatment needs.

  16. Mapping Hydrophobicity on the Protein Molecular Surface at Atom-Level Resolution

    Science.gov (United States)

    Nicolau Jr., Dan V.; Paszek, Ewa; Fulga, Florin; Nicolau, Dan V.

    2014-01-01

    A precise representation of the spatial distribution of hydrophobicity, hydrophilicity and charges on the molecular surface of proteins is critical for the understanding of the interaction with small molecules and larger systems. The representation of hydrophobicity is rarely done at atom-level, as this property is generally assigned to residues. A new methodology for the derivation of atomic hydrophobicity from any amino acid-based hydrophobicity scale was used to derive 8 sets of atomic hydrophobicities, one of which was used to generate the molecular surfaces for 35 proteins with convex structures, 5 of which, i.e., lysozyme, ribonuclease, hemoglobin, albumin and IgG, have been analyzed in more detail. Sets of the molecular surfaces of the model proteins have been constructed using spherical probes with increasingly large radii, from 1.4 to 20 Å, followed by the quantification of (i) the surface hydrophobicity; (ii) their respective molecular surface areas, i.e., total, hydrophilic and hydrophobic area; and (iii) their relative densities, i.e., divided by the total molecular area; or specific densities, i.e., divided by property-specific area. Compared with the amino acid-based formalism, the atom-level description reveals molecular surfaces which (i) present an approximately two times more hydrophilic areas; with (ii) less extended, but between 2 to 5 times more intense hydrophilic patches; and (iii) 3 to 20 times more extended hydrophobic areas. The hydrophobic areas are also approximately 2 times more hydrophobicity-intense. This, more pronounced “leopard skin”-like, design of the protein molecular surface has been confirmed by comparing the results for a restricted set of homologous proteins, i.e., hemoglobins diverging by only one residue (Trp37). These results suggest that the representation of hydrophobicity on the protein molecular surfaces at atom-level resolution, coupled with the probing of the molecular surface at different geometric resolutions

  17. Two Surface-Tension Formulations For The Level Set Interface-Tracking Method

    International Nuclear Information System (INIS)

    Shepel, S.V.; Smith, B.L.

    2005-01-01

    The paper describes a comparative study of two surface-tension models for the Level Set interface tracking method. In both models, the surface tension is represented as a body force, concentrated near the interface, but the technical implementation of the two options is different. The first is based on a traditional Level Set approach, in which the surface tension is distributed over a narrow band around the interface using a smoothed Delta function. In the second model, which is based on the integral form of the fluid-flow equations, the force is imposed only in those computational cells through which the interface passes. Both models have been incorporated into the Finite-Element/Finite-Volume Level Set method, previously implemented into the commercial Computational Fluid Dynamics (CFD) code CFX-4. A critical evaluation of the two models, undertaken in the context of four standard Level Set benchmark problems, shows that the first model, based on the smoothed Delta function approach, is the more general, and more robust, of the two. (author)

  18. Determination of mercury (II) ions based on silver-nanoparticles-assisted growth of gold nanostructures: UV-Vis and surface enhanced Raman scattering approaches

    Science.gov (United States)

    Chen, Jun-Liang; Yang, Pei-Chia; Wu, Tsunghsueh; Lin, Yang-Wei

    2018-06-01

    Innovative dual detection methods for mercury(II) ions (Hg(II)) have been developed based on the formation of gold nanostructures (AuNSs) following the addition of mercury-containing solution to a mixture containing an optimized amount of Au(III), H2O2, HCl, and silver nanoparticles (AgNPs). In the absence of Hg(II), the addition of Au(III), H2O2, and HCl to the AgNP solution changes the solution's color from yellow to red, and the absorption peak shifts from 400 to 526 nm, indicating the dissolution of AgNPs and the formation of gold nanoparticles (AuNPs). Because of the spontaneous redox reaction of Hg(II) toward AgNPs, the change in the amount of remaining AgNP seed facilitates the generation of irregular AuNSs, resulting in changes in absorption intensity and shifting the peak within the range from 526 to 562 nm depending on the concentration of Hg(II). Under optimal conditions, the limit of detection (LOD) for Hg(II) at a signal-to-noise ratio (S/N) of 3 was 0.3 μM. We further observed that AgNP-assisted catalytic formation of Au nanomaterials deposited on a surface enhanced Raman scattering active substrate significantly reduced the Raman signal of 4-mercaptobenzoic acid, dependent on the Hg(II) concentration. A linear relationship was observed in the range 0.1 nM-100 μM with a LOD of 0.05 nM (S/N 3.0). As a simple, accurate and precise method, this SERS-based assay has demonstrated its success in determining levels of Hg(II) in real water samples.

  19. Occupational exposure to beryllium in French enterprises: a survey of airborne exposure and surface levels.

    Science.gov (United States)

    Vincent, Raymond; Catani, Jacques; Créau, Yvon; Frocaut, Anne-Marie; Good, Andrée; Goutet, Pierre; Hou, Alain; Leray, Fabrice; André-Lesage, Marie-Ange; Soyez, Alain

    2009-06-01

    An assessment survey of occupational exposure to beryllium (Be) was conducted in France between late 2004 and the end of 2006. Exposure estimates were based on the analytical results of samples collected from workplace air and from work surfaces in 95 facilities belonging to 37 sectors of activity. The results of this study indicated airborne Be concentrations in excess of the occupational exposure limit value of 2 microg m(-3) recommended in France. Metallurgy and electronic component manufacturing represented the activities and occupations where workers had the highest arithmetic mean exposures to Be. Surface contamination levels were also high and frequently exceeded thresholds recommended by different bodies. These results should prompt the development of prevention programmes that include Be substitution, process control and surface decontamination, in conjunction with suitable medical surveillance.

  20. Hydraulics and drones: observations of water level, bathymetry and water surface velocity from Unmanned Aerial Vehicles

    DEFF Research Database (Denmark)

    Bandini, Filippo

    -navigable rivers and overpass obstacles (e.g. river structures). Computer vision, autopilot system and beyond visual line-of-sight (BVLOS) flights will ensure the possibility to retrieve hyper-spatial observations of water depth, without requiring the operator to access the area. Surface water speed can......The planet faces several water-related threats, including water scarcity, floods, and pollution. Satellite and airborne sensing technology is rapidly evolving to improve the observation and prediction of surface water and thus prevent natural disasters. While technological developments require....... Although UAV-borne measurements of surface water speed have already been documented in the literature, a novel approach was developed to avoid GCPs. This research is the first demonstration that orthometric water level can be measured from UAVs with a radar system and a GNSS (Global Navigation Satellite...

  1. GHRSST Level 4 MUR Global Foundation Sea Surface Temperature Analysis (v4.1) (GDS versions 1 and 2)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis produced as a retrospective dataset (four day latency) and...

  2. GHRSST Level 4 RTO Terra MODIS-AMSRE Day North America Regional Blended Sea Surface Temperature Analysis (GDS version 1)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis produced daily on an operational basis at the JPL Physical...

  3. GHRSST Level 4 RTO Terra MODIS-AMSRE Night North America Regional Blended Sea Surface Temperature Analysis (GDS version 1)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis produced daily on an operational basis at the JPL Physical...

  4. GHRSST Level 4 ODYSSEA North-Western Europe Regional Foundation Sea Surface Temperature Analysis (GDS version 1)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis produced daily on an operational basis at Ifremer/CERSAT...

  5. GHRSST Level 4 DMI_OI North Sea and Baltic Sea Regional Foundation Sea Surface Temperature Analysis (GDS version 1)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis produced daily on an operational basis by the Danish...

  6. GHRSST Level 4 RTO Aqua MODIS-AMSRE Night North America Regional Blended Sea Surface Temperature Analysis (GDS version 1)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis produced daily on an operational basis at the JPL Physical...

  7. GHRSST Level 4 RTO Aqua MODIS-AMSRE Day North America Regional Blended Sea Surface Temperature Analysis (GDS version 1)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature analysis produced daily on an operational basis at the JPL Physical...

  8. GHRSST Level 4 CMC0.1deg Global Foundation Sea Surface Temperature Analysis (GDS version 2)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature (SST) analysis produced daily on an operational basis at the Canadian...

  9. GHRSST Level 4 REMO_OI_SST_5km Regional Foundation Sea Surface Temperature Analysis (GDS version 2)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature (SST) analysis produced daily on an operational basis by the...

  10. GHRSST Level 4 CMC0.2deg Global Foundation Sea Surface Temperature Analysis (GDS version 2)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) Level 4 sea surface temperature (SST) analysis produced daily on an operational basis at the Canadian...

  11. GHRSST Level 4 MW_IR_OI Global Foundation Sea Surface Temperature analysis (GDS versions 1 and 2)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A Group for High Resolution Sea Surface Temperature (GHRSST) global Level 4 sea surface temperature analysis produced daily on a 0.81 degree grid at Remote Sensing...

  12. Sensitive determination of dopamine levels via surface-enhanced Raman scattering of Ag nanoparticle dimers.

    Science.gov (United States)

    Yu, Xiantong; He, XiaoXiao; Yang, Taiqun; Zhao, Litao; Chen, Qichen; Zhang, Sanjun; Chen, Jinquan; Xu, Jianhua

    2018-01-01

    Dopamine (DA) is an important neurotransmitter in the hypothalamus and pituitary gland, which can produce a direct influence on mammals' emotions in midbrain. Additionally, the level of DA is highly related with some important neurologic diseases such as schizophrenia, Parkinson, and Huntington's diseases, etc. In light of the important roles that DA plays in the disease modulation, it is of considerable significance to develop a sensitive and reproducible approach for monitoring DA. The objective of this study was to develop an efficient approach to quantitatively monitor the level of DA using Ag nanoparticle (NP) dimers and enhanced Raman spectroscopy. Ag NP dimers were synthesized for the sensitive detection of DA via surface-enhanced Raman scattering (SERS). Citrate was used as both the capping agent of NPs and sensing agent to DA, which is self-assembled on the surface of Ag NP dimers by reacting with the surface carboxyl group to form a stable amide bond. To improve accuracy and precision, the multiplicative effects model for surface-enhanced Raman spectroscopy was utilized to analyze the SERS assays. A low limits of detection (LOD) of 20 pM and a wide linear response range from 30 pM to 300 nM were obtained for DA quantitative detection. The SERS enhancement factor was theoretically valued at approximately 10 7 by discrete dipole approximation. DA was self-assembled on the citrate capped surface of Ag NPs dimers through the amide bond. The adsorption energy was estimated to be 256 KJ/mol using the Langmuir isotherm model. The density functional theory was used to simulate the spectral characteristics of SERS during the adsorption of DA on the surface of the Ag dimers. Furthermore, to improve the accuracy and precision of quantitative analysis of SERS assays with a multiplicative effects model for surface-enhanced Raman spectroscopy. A LOD of 20 pM DA-level was obtained, and the linear response ranged from 30 pM to 300 nM for quantitative DA detection. The

  13. An evaluation of the infection control potential of a UV clinical podiatry unit.

    Science.gov (United States)

    Humphreys, Paul N; Davies, Chris S; Rout, Simon

    2014-02-28

    Infection control is a key issue in podiatry as it is in all forms of clinical practice. Airborne contamination may be particularly important in podiatry due to the generation of particulates during treatment. Consequently, technologies that prevent contamination in podiatry settings may have a useful role. The aims of this investigation were twofold, firstly to determine the ability of a UV cabinet to protect instruments from airborne contamination and secondly to determine its ability to remove microbes from contaminated surfaces and instruments. A UV instrument cabinet was installed in a University podiatry suite. Impact samplers and standard microbiological techniques were used to determine the nature and extent of microbial airborne contamination. Sterile filters were used to determine the ability of the UV cabinet to protect exposed surfaces. Artificially contaminated instruments were used to determine the ability of the cabinet to remove microbial contamination. Airborne bacterial contamination was dominated by Gram positive cocci including Staphylococcus aureus. Airborne fungal levels were much lower than those observed for bacteria. The UV cabinet significantly reduced (p podiatry settings due to the presence of S. aureus. The use of a UV instrument cabinet can reduce the risk of contamination by airborne microbes. The UV cabinet tested was unable to decontaminate instruments and as such could pose an infection risk if misused.

  14. Characterization of ZnO coated polyester fabrics for UV protection

    International Nuclear Information System (INIS)

    Broasca, G.; Borcia, G.; Dumitrascu, N.; Vrinceanu, N.

    2013-01-01

    The textile industry aims to develop fabrics adapted to environmental conditions, in particular to UV radiation. Taking into account the demand for such materials, we prepare an inorganic–organic material, based on ZnO microparticles impregnation of polyester textiles, to perform combined UV-protection properties and high hydrophobicity. Scanning electron microscopy, UV reflectance, Impedance Spectroscopy, contact angle, air permeability, resistance to vapor transfer and tensile strength measurement are used for analysis of the surface and volume properties, related to the performance of the material under environmental conditions, as UV radiation, water and water vapors. The impregnation method ensures a good homogeneity and dispersion of ZnO microparticles into the textile polymeric matrix. The optimum level of impregnation of the fabrics is established to 3–5% ZnO, yielding stable properties, without overloading the fabric. The response of the coated polymer indicates better absorbing the UV radiation and dissipating the surface charge, time stability against UV and higher hydrophobic character, without modification of the mechanical properties, offering enhanced performance and comfort under environmental conditions.

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

    Science.gov (United States)

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

    2016-12-01

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

  16. Retrievable surface storage: interim storage of solidified high-level waste

    International Nuclear Information System (INIS)

    LaRiviere, J.R.; Nelson, D.C.

    1976-01-01

    Studies have been conducted on retrievable-surface-storage concepts for the interim storage of solidified high-level wastes. These studies have been reviewed by the Panel on Engineered Storage, convened by the Committee on Radioactive Waste Management of the National Research Council-National Academy of Sciences. The Panel has concluded that ''retrievable surface storage is an acceptable interim stage in a comprehensive system for managing high-level radioactive wastes.'' The scaled storage cask concept, which was recommended by the Panel on Engineered Storage, consists of placing a canister of waste inside a carbon-steel cask, which in turn is placed inside a thick concrete cylinder. The waste is cooled by natural convection air flow through an annulus between the cask and the inner wall of the concrete cylinder. The complete assembly is placed above ground in an outdoor storage area

  17. Surface shift of the occupied and unoccupied 4f levels of the rare-earth metals

    DEFF Research Database (Denmark)

    Aldén, Magnus; Johansson, Börje; Skriver, Hans Lomholt

    1995-01-01

    The surface energy shifts of the occupied and unoccupied 4f levels for the lanthanide metals have been calculated from first principles by means of a Green’s-function technique within the tight-binding linear muffin-tin orbitals method. We use the concept of complete screening to identify...... the occupied and unoccupied 4f energy level shifts as the surface segregation energy of a 4fn-1 and 4fn+1 impurity atom, respectively, in a 4fn host metal. The calculations include both initial- and final-state effects and give values that are considerably lower than those measured on polycrystalline samples...... as well as those found in previous initial-state model calculations. The present theory agrees well with very recent high-resolution, single-crystal film measurements for Gd, Tb, Dy, Ho, Er, Tm, and Lu. We furthermore utilize the unique possibility offered by the lanthanide metals to clarify the roles...

  18. UV Reconstruction Algorithm And Diurnal Cycle Variability

    Science.gov (United States)

    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.

  19. Site characterization field manual for near surface geologic disposal of low-level radioactive waste

    International Nuclear Information System (INIS)

    McCray, J.G.; Nowatzki, E.A.

    1985-01-01

    This field manual has been developed to aid states and regions to do a detailed characterization of a proposed near-surface low-level waste disposal site. The field manual is directed at planners, staff personnel and experts in one discipline to acquaint them with the requirements of other disciplines involved in site characterization. While it can provide a good review, it is not designed to tell experts how to do their job within their own discipline

  20. Polarization-induced renormalization of molecular levels at metallic and semiconducting surfaces

    DEFF Research Database (Denmark)

    García Lastra, Juan Maria; Rostgaard, Carsten; Rubio, A.

    2009-01-01

    On the basis of first-principles G0W0 calculations we systematically study how the electronic levels of a benzene molecule are renormalized by substrate polarization when physisorbed on different metallic and semiconducting surfaces. The polarization-induced reduction in the energy gap between oc...... find that error cancellations lead to remarkably good agreement between the G0W0 and Kohn-Sham energies for the occupied orbitals of the adsorbed molecule....

  1. Radiation levels in the poll surface of IEA-R1 reactor

    International Nuclear Information System (INIS)

    Pasqualetto, H.

    1978-01-01

    A theoretical model for the calculation of the radioactivity level in the pool surface of the research reactor IEA-RI (INSTITUTO DE ENERGIA ATOMICA, BRAZIL) is developed. The radioactivity is caused by radionuclides (Mainly 24 Na and 27 Mg) produced by nuclear reactions of neutrons with: a) oxygen of the water b); gaseous elements dissolved in water (Ar,N); c) structural materials of the fuel can. Considerations about expected radiation level after eventual increase of reactor power from 2 MW to 10 MW are also presented [pt

  2. Iterative algorithm for reconstructing rotationally asymmetric surface deviation with pixel-level spatial resolution

    Science.gov (United States)

    Quan, Haiyang; Wu, Fan; Hou, Xi

    2015-10-01

    New method for reconstructing rotationally asymmetric surface deviation with pixel-level spatial resolution is proposed. It is based on basic iterative scheme and accelerates the Gauss-Seidel method by introducing an acceleration parameter. This modified Successive Over-relaxation (SOR) is effective for solving the rotationally asymmetric components with pixel-level spatial resolution, without the usage of a fitting procedure. Compared to the Jacobi and Gauss-Seidel method, the modified SOR method with an optimal relaxation factor converges much faster and saves more computational costs and memory space without reducing accuracy. It has been proved by real experimental results.

  3. Wetland Ecohydrology: stochastic description of water level fluctuations across the soil surface

    Science.gov (United States)

    Tamea, S.; Muneepeerakul, R.; Laio, F.; Ridolfi, L.; Rodriguez-Iturbe, I.

    2009-12-01

    Wetlands provide a suite of social and ecological critical functions such as being habitats of disease-carrying vectors, providing buffer zones against hurricanes, controlling sediment transport, filtering nutrients and contaminants, and a repository of great biological diversity. More recently, wetlands have also been recognized as crucial for carbon storage in the context of global climate change. Despite such importance, quantitative approaches to many aspects of wetlands are far from adequate. Therefore, improving our quantitative understanding of wetlands is necessary to our ability to maintain, manage, and restore these invaluable environments. In wetlands, hydrologic factors and ecosystem processes interplay and generate unique characteristics and a delicate balance between biotic and abiotic elements. The main hydrologic driver of wetland ecosystems is the position of the water level that, being above or below ground, determines the submergence or exposure of soil. When the water level is above the soil surface, soil saturation and lack of oxygen causes hypoxia, anaerobic functioning of microorganisms and anoxic stress in plants, that might lead to the death of non-adapted organisms. When the water level lies below the soil surface, the ecosystem becomes groundwater-dependent, and pedological and physiological aspects play their role in the soil water balance. We propose here a quantitative description of wetland ecohydrology, through a stochastic process-based water balance, driven by a marked compound Poisson noise representing rainfall events. The model includes processes such as rainfall infiltration, evapotranspiration, capillary rise, and the contribution of external water bodies, which are quantified in a simple yet realistic way. The semi-analytical steady-state probability distributions of water level spanning across the soil surface are validated with data from the Everglades (Florida, USA). The model and its results allow for a quantitative

  4. Comets in UV

    Science.gov (United States)

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

    2018-04-01

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

  5. Development, Characterization, and Optimization of Protein Level in Date Bars Using Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    Muhammad Nadeem

    2012-01-01

    Full Text Available This project was designed to produce a nourishing date bar with commercial value especially for school going children to meet their body development requirements. Protein level of date bars was optimized using response surface methodology (RSM. Economical and underutilized sources, that is, whey protein concentrate and vetch protein isolates, were explored for protein supplementation. Fourteen date bar treatments were produced using a central composite design (CCD with 2 variables and 3 levels for each variable. Date bars were then analyzed for nutritional profile. Proximate composition revealed that addition of whey protein concentrate and vetch protein isolates improved the nutritional profile of date bars. Protein level, texture, and taste were considerably improved by incorporating 6.05% whey protein concentrate and 4.35% vetch protein isolates in date bar without affecting any sensory characteristics during storage. Response surface methodology was observed as an economical and effective tool to optimize the ingredient level and to discriminate the interactive effects of independent variables.

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

    Science.gov (United States)

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

    2017-09-01

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

  7. UV exposure in cars.

    Science.gov (United States)

    Moehrle, Matthias; Soballa, Martin; Korn, Manfred

    2003-08-01

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

  8. Surface-type repository for low and intermediate level radioactive waste in the Republic of Croatia

    International Nuclear Information System (INIS)

    Kucar-Dragicevic, S.; Zarkovic, V.; Subasic, D.

    1995-01-01

    The low-level intermediate-level (LL/IL) radioactive waste repository siting and construction project is one of the activities related to establishing the rad waste management system in the Republic of Croatia. The repository project design is one in an array of project activities which also include the site selection procedure and public attitude issues. The prepared design documentation gives technical, safety and financial background relevant for making a final decision on the waste disposal type, and it includes the technological, mechanical, civil and financial documentation on the preliminary/basic design level. During the last few years, the preliminary design has been prepared and safety assessment conducted for the tunnel-type LL/IL rad waste repository. As the surface-type repository is one of alternatives for final disposal the design documentation for that repository type was prepared during 1994. (author)

  9. Evaluation of bubbler/diaphragm techniques to measure surface level in the waste storage tanks

    International Nuclear Information System (INIS)

    Peters, T.J.; Hickman, B.J.; Colson, J.B.

    1993-10-01

    This report describes the results of tests conducted at the Pacific Northwest Laboratory (PNL) to determine if a bubbler technique can be used to determine the surface level in the waste tanks. Two techniques were evaluated. The first technique is a standard bubbler system in which a tube is placed below the surface of the liquid to be measured and air pressure inside a tube is increased until bubbles begin to become emitted from the tube. The air pressure then is a function of the pressure at the bottom of the tube. The second technique involves a system similar to the standard bubbler technique, but instead of bubbles being released into the material to be gauged, air pressure is increased against a diaphragm until enough pressure is applied to overcome the pressure of the liquid at the given depth, at which time the air then flows in a return loop back to a vent. The advantage of the diaphragm system is that it is a sealed system; thus no air is released into the waste tank materials, and it is not possible for the waste tank materials to get into the air flow. Based on the results of the tests conducted in this program, it appears that the bubbler and diaphragm systems that were tested could not be used for accurate measurements of the level in the waste tanks. Both exhibited deposits of simulated waste tank material at the end of the devices which affected the ability of the gauge to accurately determine changes in the surface level even though the measured value of the level was inaccurate. Further investigations into the cause of this inaccuracy may be warranted. Alternate diaphragm materials may improve the performance of this gauge

  10. Surface shift of the occupied and unoccupied 4f levels of the rare-earth metals

    Science.gov (United States)

    Aldén, M.; Johansson, B.; Skriver, H. L.

    1995-02-01

    The surface energy shifts of the occupied and unoccupied 4f levels for the lanthanide metals have been calculated from first principles by means of a Green's-function technique within the tight-binding linear muffin-tin orbitals method. We use the concept of complete screening to identify the occupied and unoccupied 4f energy level shifts as the surface segregation energy of a 4fn-1 and 4fn+1 impurity atom, respectively, in a 4fn host metal. The calculations include both initial- and final-state effects and give values that are considerably lower than those measured on polycrystalline samples as well as those found in previous initial-state model calculations. The present theory agrees well with very recent high-resolution, single-crystal film measurements for Gd, Tb, Dy, Ho, Er, Tm, and Lu. We furthermore utilize the unique possibility offered by the lanthanide metals to clarify the roles played by the initial and the different final states of the core-excitation process, permitted by the fact that the so-called initial-state effect is identical upon 4f removal and 4f addition. Surface energy and work function calculations are also reported.

  11. Exceptionally crystalline and conducting acid doped polyaniline films by level surface assisted solution casting approach

    Energy Technology Data Exchange (ETDEWEB)

    Puthirath, Anand B.; Varma, Sreekanth J.; Jayalekshmi, S., E-mail: jayalekshmi@cusat.ac.in [Division for Research in Advanced Materials, Department of Physics, Cochin University of Science and Technology, Cochin, Kerala 682022 (India); Methattel Raman, Shijeesh [Nanophotonic and Optoelectronic Devices Laboratory, Department of Physics, Cochin University of Science and Technology, Cochin, Kerala 682022 (India)

    2016-04-18

    Emeraldine salt form of polyaniline (PANI) was synthesized by chemical oxidative polymerisation method using ammonium persulfate as oxidant. Resultant emeraldine salt form of PANI was dedoped using ammonia solution and then re-doped with camphor sulphonic acid (CSA), naphthaline sulphonic acid (NSA), hydrochloric acid (HCl), and m-cresol. Thin films of these doped PANI samples were deposited on glass substrates using solution casting method with m-cresol as solvent. A level surface was employed to get homogeneous thin films of uniform thickness. Detailed X-ray diffraction studies have shown that the films are exceptionally crystalline. The crystalline peaks observed in the XRD spectra can be indexed to simple monoclinic structure. FTIR and Raman spectroscopy studies provide convincing explanation for the exceptional crystallinity observed in these polymer films. FESEM and AFM images give better details of surface morphology of doped PANI films. The DC electrical conductivity of the samples was measured using four point probe technique. It is seen that the samples also exhibit quite high DC electrical conductivity, about 287 S/cm for CSA doped PANI, 67 S/cm for NSA doped PANI 65 S/cm for HCl doped PANI, and just below 1 S/cm for m-cresol doped PANI. Effect of using the level surface for solution casting is studied and correlated with the observed crystallinity.

  12. Reduction of Fermi level pinning and recombination at polycrystalline CdTe surfaces by laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Simonds, Brian J. [Electrical and Computer Engineering, University of Utah, Salt Lake City, Utah 84112 (United States); Kheraj, Vipul [Electrical and Computer Engineering, University of Utah, Salt Lake City, Utah 84112 (United States); Department of Applied Physics, S. V. National Institute of Technology, Surat 395 007 (India); Palekis, Vasilios; Ferekides, Christos [Electrical Engineering, University of South Florida, Tampa, Florida 33620 (United States); Scarpulla, Michael A., E-mail: scarpulla@eng.utah.edu [Electrical and Computer Engineering, University of Utah, Salt Lake City, Utah 84112 (United States); Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112 (United States)

    2015-06-14

    Laser processing of polycrystalline CdTe is a promising approach that could potentially increase module manufacturing throughput while reducing capital expenditure costs. For these benefits to be realized, the basic effects of laser irradiation on CdTe must be ascertained. In this study, we utilize surface photovoltage spectroscopy (SPS) to investigate the changes to the electronic properties of the surface of polycrystalline CdTe solar cell stacks induced by continuous-wave laser annealing. The experimental data explained within a model consisting of two space charge regions, one at the CdTe/air interface and one at the CdTe/CdS junction, are used to interpret our SPS results. The frequency dependence and phase spectra of the SPS signal are also discussed. To support the SPS findings, low-temperature spectrally-resolved photoluminescence and time-resolved photoluminescence were also measured. The data show that a modest laser treatment of 250 W/cm{sup 2} with a dwell time of 20 s is sufficient to reduce the effects of Fermi level pinning at the surface due to surface defects.

  13. Influence of surface melting effects and availability of reagent ions on LDI-MS efficiency after UV laser irradiation of Pd nanostructures.

    Science.gov (United States)

    Silina, Yuliya E; Koch, Marcus; Volmer, Dietrich A

    2015-03-01

    In this study, the influence of surface morphology, reagent ions and surface restructuring effects on atmospheric pressure laser desorption/ionization (LDI) for small molecules after laser irradiation of palladium self-assembled nanoparticular (Pd-NP) structures has been systematically studied. The dominant role of surface morphology during the LDI process, which was previously shown for silicon-based substrates, has not been investigated for metal-based substrates before. In our experiments, we demonstrated that both the presence of reagent ions and surface reorganization effects--in particular, melting--during laser irradiation was required for LDI activity of the substrate. The synthesized Pd nanostructures with diameters ranging from 60 to 180 nm started to melt at similar temperatures, viz. 890-898 K. These materials exhibited different LDI efficiencies, however, with Pd-NP materials being the most effective surface in our experiments. Pd nanostructures of diameters >400-800 nm started to melt at higher temperatures, >1000 K, making such targets more resistant to laser irradiation, with subsequent loss of LDI activity. Our data demonstrated that both melting of the surface structures and the presence of reagent ions were essential for efficient LDI of the investigated low molecular weight compounds. This dependence of LDI on melting points was exploited further to improve the performance of Pd-NP-based sampling targets. For example, adding sodium hypophosphite as reducing agent to Pd electrolyte solutions during synthesis lowered the melting points of the Pd-NP materials and subsequently gave reduced laser fluence requirements for LDI. Copyright © 2015 John Wiley & Sons, Ltd.

  14. UV-induced N2O emission from plants

    DEFF Research Database (Denmark)

    Bruhn, Dan; Albert, Kristian Rost; Mikkelsen, Teis Nørgaard

    2014-01-01

    investigate for the fi rst time N 2 O emission from terrestrial vegetation in response to natural solar ultra violet radiation. We conducted fi eld site measurements to investigate N 2 O atmosphere exchange from grass vegetation exposed to solar irradiance with and without UV-screening. Further laboratory...... magnitude as that to UV-B. Therefore, UV-A is more important than UV-B given the natural UV-spectrum at Earth's surface. Plants also emitted N 2 O in darkness, although at reduced rates. The emission rate is temperature dependent with a rather high activation energy indicative for an abiotic process...

  15. Relict benthic foraminifera in surface sediments off central east coast of India as indicator of sea level changes

    Digital Repository Service at National Institute of Oceanography (India)

    Rana, S.S.; Nigam, R.; Panchang, R.

    surface samples is characteristic of coral reef environment and has been inferred as evidence for past low sea levels. Based on extrapolation of previously published radiocarbon dates from the region, we propose a pliable sea level curve for the period...

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  17. UV-induced effects

    NARCIS (Netherlands)

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

    2005-01-01

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

  18. Exposure to solar UV in Finland

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-12-31

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

  19. Exposure to solar UV in Finland

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-12-31

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

  20. Past and future sea-level change from the surface mass balance of glaciers

    Directory of Open Access Journals (Sweden)

    B. Marzeion

    2012-11-01

    Full Text Available We present estimates of sea-level change caused by the global surface mass balance of glaciers, based on the reconstruction and projection of the surface mass balance of all the individual glaciers of the world, excluding the ice sheets in Greenland and Antarctica. The model is validated using a leave-one-glacier-out cross-validation scheme against 3997 observed surface mass balances of 255 glaciers, and against 756 geodetically observed, temporally integrated volume and surface area changes of 341 glaciers. When forced with observed monthly precipitation and temperature data, the glaciers of the world are reconstructed to have lost mass corresponding to 114 ± 5 mm sea-level equivalent (SLE between 1902 and 2009. Using projected temperature and precipitation anomalies from 15 coupled general circulation models from the Coupled Model Intercomparison Project phase 5 (CMIP5 ensemble, they are projected to lose an additional 148 ± 35 mm SLE (scenario RCP26, 166 ± 42 mm SLE (scenario RCP45, 175 ± 40 mm SLE (scenario RCP60, or 217 ± 47 mm SLE (scenario RCP85 during the 21st century. Based on the extended RCP scenarios, glaciers are projected to approach a new equilibrium towards the end of the 23rd century, after having lost either 248 ± 66 mm SLE (scenario RCP26, 313 ± 50 mm SLE (scenario RCP45, or 424 ± 46 mm SLE (scenario RCP85. Up until approximately 2100, ensemble uncertainty within each scenario is the biggest source of uncertainty for the future glacier mass loss; after that, the difference between the scenarios takes over as the biggest source of uncertainty. Ice mass loss rates are projected to peak 2040 ∼ 2050 (RCP26, 2050 ∼ 2060 (RCP45, 2070 ∼ 2090 (RCP60, or 2070 ∼ 2100 (RCP85.

  1. Two-Level Micro-to-Nanoscale Hierarchical TiO2 Nanolayers on Titanium Surface

    Directory of Open Access Journals (Sweden)

    Elena G. Zemtsova

    2016-12-01

    Full Text Available Joint replacement is being actively developed within modern orthopedics. One novel material providing fast implantation is bioactive coatings. The synthesis of targeted nanocoatings on metallic nanotitanium surface is reported in this paper. TiO2-based micro- and nanocoatings were produced by sol-gel synthesis using dip-coating technology with subsequent fast (shock drying in hot plate mode at 400 °C. As a result of shock drying, the two-level hierarchical TiO2 nanolayer on the nanotitanium was obtained. This two-level hierarchy includes nanorelief of porous xerogel and microrelief of the micron-sized “defect” network (a crack network. The thickness of TiO2 nanolayers was controlled by repeating dip-coating process the necessary number of times after the first layer deposition. The state of the MS3T3-E1 osteoblast cell line (young cells that form bone tissue on the two-level hierarchical surface has been studied. Particularly, adhesion character, adhesion time and morphology have been studied. The reported results may serve the starting point for the development of novel bioactive coatings for bone and teeth implants.

  2. Surface Water Connectivity, Flow Pathways and Water Level Fluctuation in a Cold Region Deltaic Ecosystem

    Science.gov (United States)

    Peters, D. L.; Niemann, O.; Skelly, R.; Monk, W. A.; Baird, D. J.

    2017-12-01

    The Peace-Athabasca Delta (PAD) is a 6000 km2 deltaic floodplain ecosystem of international importance (Wood Buffalo National Park, Ramsar Convention, UNESCO World Heritage, and SWOT satellite water level calibration/validation site). The low-relief floodplain formed at the confluence of the Peace, Athabasca and Birch rivers with Lake Athabasca. More than 1000 wetland and lake basins have varying degrees of connectivity to the main flow system. Hydroperiod and water storage is influenced by ice-jam and open-water inundations and prevailing semi-arid climate that control water drawdown. Prior studies have identified pathways of river-to-wetland floodwater connection and historical water level fluctuation/trends as a key knowledge gaps, limiting our knowledge of deltaic ecosystem status and potential hydroecological responses to climate change and upstream water alterations to flow contributions. To address this knowledge gap, surface elevation mapping of the PAD has been conducted since 2012 using aerial remote sensing Light Detection and Ranging (LiDAR), plus thousands of ground based surface and bathymetric survey points tied to Global Positioning System (GPS) were obtained. The elevation information was used to develop a high resolution digital terrain model to simulate and investigate surface water connectivity. Importantly, the surveyed areas contain a set of wetland monitoring sites where ground-based surface water connectivity, water level/depth, water quality, and aquatic ecology (eg, vegetation, macroinvertebrate and muskrat) have been examined. The goal of this presentation is to present an assessment of: i) surface water fluctuation and connectivity for PAD wetland sites; ii) 40+ year inter-annual hydroperiod reconstruction for a perched basin using a combination of field measurements, remote sensing estimates, and historical documents; and iii) outline an approach to integrate newly available hydro-bio-geophysical information into a novel, multi

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

    Science.gov (United States)

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

    2008-11-01

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

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

    Science.gov (United States)

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

    2016-08-01

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

  5. Silane effects on the surface morphology and abrasion resistance of transparent SiO2/UV-curable resin nano-composites

    International Nuclear Information System (INIS)

    Hsiang, Hsing-I.; Chang, Yu-Lun; Chen, Chi-Yu; Yen, Fu-Su

    2011-01-01

    Transparent ultraviolet curable nano-composite coatings consisting of nano-sized SiO 2 and acrylate resin have been developed to improve the abrasion resistance of organic polymers. The nano-sized SiO 2 particles were surface-modified using various amounts of 3-methacryloxypropyltrimethoxysilane. The 3-methacryloxypropyltrimethoxysilane concentration effects on the surface morphology and abrasion resistance of the transparent SiO 2 /ultraviolet-curable resin nano-composites were investigated using scanning electron microscopy, atomic force microscopy, and ultraviolet-visible spectrophotometer. The results showed that as the 3-methacryloxypropyltrimethoxysilane/SiO 2 weight ratio increased from 0.2 to 0.6, the dispersion, compatibility and cross-linking density between the 3-methacryloxypropyltrimethoxysilane-modified SiO 2 particles and acrylate resin were improved, leading to an increase in abrasion resistance. However, as the 3-methacryloxypropyltrimethoxysilane/SiO 2 weight ratio was increased to 1.5, the additional 3-methacryloxypropyltrimethoxysilane may exceed that needed to fill the pores with the probability of SiO 2 nano-particles existing on the coating surface was lower than that for samples with a 3-methacryloxypropyltrimethoxysilane/SiO 2 weight ratio of 0.6. This produced a decrease in abrasion resistance.

  6. An examination of endoparasites and fecal testosterone levels in flying squirrels (Glaucomys spp.) using high performance liquid chromatography-ultra-violet (HPLC-UV)

    OpenAIRE

    Waksmonski, Sarah N.; Huffman, Justin M.; Mahan, Carolyn G.; Steele, Michael A.

    2017-01-01

    The immuno-competence hypothesis proposes that higher levels of testosterone increases the susceptibility to parasitism. Here we examined the testosterone levels in two species of flying squirrels (Glaucomys): one known to regularly host a nematode species (Strongyloides robustus) without ill effects (G. volans) and a closely related species that is considered negatively affected by the parasite. We quantified fecal testosterone levels in northern and southern flying squirrels (G. sabrinus, G...

  7. Project of the Year Submittal SY-101 Surface Level Rise Remediation Project

    International Nuclear Information System (INIS)

    BAUER, R.E.

    2001-01-01

    CH2M HILL Hanford Group is pleased to nominate the SY-101 Surface Level Rise Remediation Project (SLRRP) for the Project Management Institute's consideration as International Project of the Year for 2001. We selected this project as being our best recent example of effective project management, having achieved and exceeded our client's expectations in resolving urgent safety issues related to the storage of high level nuclear waste. In reflection, we consider the SY-101 SLRRP to be a prime example of safe and effective project delivery. The pages that follow present the tools and techniques employed to manage this complex and technically challenging project. Our objective in submitting this nomination is twofold--to share the lessons we have learned with other organizations, and to honor the men and women who contributed to this endeavor. It was by their diligent effort that the successes we relate here were accomplished 10 months ahead of schedule and one million dollars below the authorized budget

  8. Effect of age and gender on the surface electromyogram during various levels of isometric contraction.

    Science.gov (United States)

    Arjunan, Sridhar; Kumar, Dinesh; Kalra, Chandan; Burne, John; Bastos, Teodiano

    2011-01-01

    This study reports the effects of age and gender on the surface electromyogram while performing isometric contraction. Experiments were conducted with two age groups--Young (Age: 20-29) and Old (Age: 60-69) where they performed sustained isometric contractions at various force levels (50%, 75%, 100% of maximum voluntary contraction). Traditional features such as root mean square (RMS) and median frequency (MDF) were computed from the recorded sEMG. The result indicates that the MDF of sEMG was not significantly affected by age, but was impacted by gender in both age groups. Also there was a significant change in the RMS of sEMG with age and gender at all levels of contraction. The results also indicate a large inter-subject variation. This study will provide an understanding of the underlying physiological effects of muscle contraction and muscle fatigue in different cohorts.

  9. The SMAP Level 4 Surface and Root-zone Soil Moisture (L4_SM) Product

    Science.gov (United States)

    Reichle, Rolf; Crow, Wade; Koster, Randal; Kimball, John

    2010-01-01

    The Soil Moisture Active and Passive (SMAP) mission is being developed by NASA for launch in 2013 as one of four first-tier missions recommended by the U.S. National Research Council Committee on Earth Science and Applications from Space in 2007. The primary science objectives of SMAP are to enhance understanding of land surface controls on the water, energy and carbon cycles, and to determine their linkages. Moreover, the high resolution soil moisture mapping provided by SMAP has practical applications in weather and seasonal climate prediction, agriculture, human health, drought and flood decision support. In this paper we describe the assimilation of SMAP observations for the generation of the planned SMAP Level 4 Surface and Root-zone Soil Moisture (L4_SM) product. The SMAP mission makes simultaneous active (radar) and passive (radiometer) measurements in the 1.26-1.43 GHz range (L-band) from a sun-synchronous low-earth orbit. Measurements will be obtained across a 1000 km wide swath using conical scanning at a constant incidence angle (40 deg). The radar resolution varies from 1-3 km over the outer 70% of the swath to about 30 km near the center of the swath. The radiometer resolution is 40 km across the entire swath. The radiometer measurements will allow high-accuracy but coarse resolution (40 km) measurements. The radar measurements will add significantly higher resolution information. The radar is however very sensitive to surface roughness and vegetation structure. The combination of the two measurements allows optimal blending of the advantages of each instrument. SMAP directly observes only surface soil moisture (in the top 5 cm of the soil column). Several of the key applications targeted by SMAP, however, require knowledge of root zone soil moisture (approximately top 1 m of the soil column), which is not directly measured by SMAP. The foremost objective of the SMAP L4_SM product is to fill this gap and provide estimates of root zone soil moisture

  10. Comparison pesticide residue levels in the surface of Bertam River in Cameron Highlands, Pahang

    Energy Technology Data Exchange (ETDEWEB)

    Haron, S. H., E-mail: ismail@ukm.edu.my; Ismail, B. S., E-mail: sthumaira@yahoo.com [School of Environmental and Natural Resource Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia 43600 UKM, Bangi, Selangor (Malaysia)

    2015-09-25

    The presence of pesticide residues in the surface water of Bertam River in the agricultural areas of Cameron Highlands in Pahang, Malaysia was monitored from May to October 2014. The sampling sites were located at 10 sampling points along the Bertam River in the vegetable planting areas. The extraction method of the pesticide (organophosphate/pyrethroid) from the river samples used solid phase extraction followed by gas chromatography (with electron capture detector, ECD). Insecticides, cypermethrin and chlorpyrifos were found in the surface water of Bertam River. High level concentrations of those insecticides in the river were observed during the period from May to October 2014, a period which included both seasons (wet and dry seasons). The highest concentration of 2.66 µg/mL and 1.23 µg/mL of cypermethrin was observed during the wet and dry seasons respectively. This could be due to the frequent usage of the above-mentioned insecticides coupled with contamination that could have originated from the application sites. Meanwhile, the lowest concentration detected in the surface water was chlorpyrifos (0.11 µg/mL and 0.17 µg/mL) during the dry and wet seasons, respectively.

  11. Comparison pesticide residue levels in the surface of Bertam River in Cameron Highlands, Pahang

    International Nuclear Information System (INIS)

    Haron, S. H.; Ismail, B. S.

    2015-01-01

    The presence of pesticide residues in the surface water of Bertam River in the agricultural areas of Cameron Highlands in Pahang, Malaysia was monitored from May to October 2014. The sampling sites were located at 10 sampling points along the Bertam River in the vegetable planting areas. The extraction method of the pesticide (organophosphate/pyrethroid) from the river samples used solid phase extraction followed by gas chromatography (with electron capture detector, ECD). Insecticides, cypermethrin and chlorpyrifos were found in the surface water of Bertam River. High level concentrations of those insecticides in the river were observed during the period from May to October 2014, a period which included both seasons (wet and dry seasons). The highest concentration of 2.66 µg/mL and 1.23 µg/mL of cypermethrin was observed during the wet and dry seasons respectively. This could be due to the frequent usage of the above-mentioned insecticides coupled with contamination that could have originated from the application sites. Meanwhile, the lowest concentration detected in the surface water was chlorpyrifos (0.11 µg/mL and 0.17 µg/mL) during the dry and wet seasons, respectively

  12. Self-consistent Green’s-function technique for bulk and surface impurity calculations: Surface core-level shifts by complete screening

    DEFF Research Database (Denmark)

    Aldén, M.; Abrikosov, I. A.; Johansson, B.

    1994-01-01

    of the frozen-core and atomic-sphere approximation but, in addition, includes the dipole contribution to the intersphere potential. Within the concept of complete screening, we identify the surface core-level binding-energy shift with the surface segregation energy of a core-ionized atom and use the Green......'s-function impurity technique in a comprehensive study of the surface core-level shifts (SCLS) of the 4d and 5d transition metals. In those cases, where observed data refer to single crystals, we obtain good agreement with experiment, whereas the calculations typically underestimate the measured shift obtained from...

  13. Robust space-time extraction of ventricular surface evolution using multiphase level sets

    Science.gov (United States)

    Drapaca, Corina S.; Cardenas, Valerie; Studholme, Colin

    2004-05-01

    This paper focuses on the problem of accurately extracting the CSF-tissue boundary, particularly around the ventricular surface, from serial structural MRI of the brain acquired in imaging studies of aging and dementia. This is a challenging problem because of the common occurrence of peri-ventricular lesions which locally alter the appearance of white matter. We examine a level set approach which evolves a four dimensional description of the ventricular surface over time. This has the advantage of allowing constraints on the contour in the temporal dimension, improving the consistency of the extracted object over time. We follow the approach proposed by Chan and Vese which is based on the Mumford and Shah model and implemented using the Osher and Sethian level set method. We have extended this to the 4 dimensional case to propagate a 4D contour toward the tissue boundaries through the evolution of a 5D implicit function. For convergence we use region-based information provided by the image rather than the gradient of the image. This is adapted to allow intensity contrast changes between time frames in the MRI sequence. Results on time sequences of 3D brain MR images are presented and discussed.

  14. Low-Cost Alternative for the Measurement of Water Levels in Surface Water Streams

    Directory of Open Access Journals (Sweden)

    Luis E. PEÑA

    2017-11-01

    Full Text Available Flood risk management and water resources planning involve a deep knowledge of surface streams so that mitigation strategies and climate change adaptations can be implemented. Commercially, there is a wide range of technologies for the measurement of hydroclimatic variables; however, many of these technologies may not be affordable for institutions with limited budgets. This paper has two main objectives: 1 Present the design of an ultrasound-based water level measurement system, and 2 Propose a methodological alternative for the development of instruments, according to the needs of institutions conducting monitoring of surface waterbodies. To that end, the proposed methodology is based on selection processes defined according to the specific needs of each waterbody. The prototype was tested in real-world scale, with the potential to obtain accurate measurements. Lastly, we present the design of the ultrasound-based water level measurement instrument, which can be built at a low cost. Low-cost instruments can potentially contribute to the sustainable instrumental autonomy of environmental entities and help define measurement and data transmission standards based on the specific requirements of the monitoring.

  15. Fabrication of Surface Level Cu/Si Cp Nano composites by Friction Stir Processing Route

    International Nuclear Information System (INIS)

    Srinivasan, R. C.; Karunanithi, M.

    2015-01-01

    Friction stir processing (FSP) technique has been successfully employed as low energy consumption route to prepare copper based surface level nano composites reinforced with nano sized silicon carbide particles (Si Cp). The effect of FSP parameters such as tool rotational speed, processing speed, and tool tilt angle on microstructure and microhardness was investigated. Single pass FSP was performed based on Box-Behnken design at three factors in three levels. A cluster of blind holes 2 mm in diameter and 3 mm in depth was used as particulate deposition technique in order to reduce the agglomeration problem during composite fabrication. K-type thermocouples were used to measure temperature histories during FSP. The results suggest that the heat generation during FSP plays a significant role in deciding the microstructure and microhardness of the surface composites. Microstructural observations revealed a uniform dispersion of nano sized Si Cp without any agglomeration problem and well bonded with copper matrix at different process parameter combinations. X-ray diffraction study shows that no intermetallic compound was produced after processing. The microhardness of nano composites was remarkably enhanced and about 95% more than that of copper matrix

  16. Fabrication of Surface Level Cu/SiCp Nanocomposites by Friction Stir Processing Route

    Directory of Open Access Journals (Sweden)

    Cartigueyen Srinivasan

    2015-01-01

    Full Text Available Friction stir processing (FSP technique has been successfully employed as low energy consumption route to prepare copper based surface level nanocomposites reinforced with nanosized silicon carbide particles (SiCp. The effect of FSP parameters such as tool rotational speed, processing speed, and tool tilt angle on microstructure and microhardness was investigated. Single pass FSP was performed based on Box-Behnken design at three factors in three levels. A cluster of blind holes 2 mm in diameter and 3 mm in depth was used as particulate deposition technique in order to reduce the agglomeration problem during composite fabrication. K-type thermocouples were used to measure temperature histories during FSP. The results suggest that the heat generation during FSP plays a significant role in deciding the microstructure and microhardness of the surface composites. Microstructural observations revealed a uniform dispersion of nanosized SiCp without any agglomeration problem and well bonded with copper matrix at different process parameter combinations. X-ray diffraction study shows that no intermetallic compound was produced after processing. The microhardness of nanocomposites was remarkably enhanced and about 95% more than that of copper matrix.

  17. Reduction Expansion Synthesis as Strategy to Control Nitrogen Doping Level and Surface Area in Graphene

    Directory of Open Access Journals (Sweden)

    Russell Canty

    2015-10-01

    Full Text Available Graphene sheets doped with nitrogen were produced by the reduction-expansion (RES method utilizing graphite oxide (GO and urea as precursor materials. The simultaneous graphene generation and nitrogen insertion reactions are based on the fact that urea decomposes upon heating to release reducing gases. The volatile byproducts perform two primary functions: (i promoting the reduction of the GO and (ii providing the nitrogen to be inserted in situ as the graphene structure is created. Samples with diverse urea/GO mass ratios were treated at 800 °C in inert atmosphere to generate graphene with diverse microstructural characteristics and levels of nitrogen doping. Scanning electron microscopy (SEM and transmission electron microscopy (TEM were used to study the microstructural features of the products. The effects of doping on the samples structure and surface area were studied by X-ray diffraction (XRD, Raman Spectroscopy, and Brunauer Emmet Teller (BET. The GO and urea decomposition-reduction process as well as nitrogen-doped graphene stability were studied by thermogravimetric analysis (TGA coupled with mass spectroscopy (MS analysis of the evolved gases. Results show that the proposed method offers a high level of control over the amount of nitrogen inserted in the graphene and may be used alternatively to control its surface area. To demonstrate the practical relevance of these findings, as-produced samples were used as electrodes in supercapacitor and battery devices and compared with conventional, thermally exfoliated graphene.

  18. Synchrotron macro ATR-FTIR microspectroscopic analysis of silica nanoparticle-embedded polyester coated steel surfaces subjected to prolonged UV and humidity exposure.

    Directory of Open Access Journals (Sweden)

    Jitraporn Vongsvivut

    Full Text Available Surface modification of polymers and paints is a popular and effective way to enhance the properties of these materials. This can be achieved by introducing a thin coating that preserves the bulk properties of the material, while protecting it from environmental exposure. Suitable materials for such coating technologies are inorganic oxides, such as alumina, titania and silica; however, the fate of these materials during long-term environmental exposure is an open question. In this study, polymer coatings that had been enhanced with the addition of silica nanoparticles (SiO2NPs and subsequently subjected to environmental exposure, were characterized both before and after the exposure to determine any structural changes resulting from the exposure. High-resolution synchrotron macro ATR-FTIR microspectroscopy and surface topographic techniques, including optical profilometry and atomic force microscopy (AFM, were used to determine the long-term effect of the environment on these dual protection layers after 3 years of exposure to tropical and sub-tropical climates in Singapore and Queensland (Australia. Principal component analysis (PCA based on the synchrotron macro ATR-FTIR spectral data revealed that, for the 9% (w/w SiO2NP/polymer coating, a clear discrimination was observed between the control group (no environmental exposure and those samples subjected to three years of environmental exposure in both Singapore and Queensland. The PCA loading plots indicated that, over the three year exposure period, a major change occurred in the triazine ring vibration in the melamine resins. This can be attributed to the triazine ring being very sensitive to hydrolysis under the high humidity conditions in tropical/sub-tropical environments. This work provides the first direct molecular evidence, acquired using a high-resolution mapping technique, of the climate-induced chemical evolution of a polyester coating. The observed changes in the surface

  19. Synchrotron macro ATR-FTIR microspectroscopic analysis of silica nanoparticle-embedded polyester coated steel surfaces subjected to prolonged UV and humidity exposure.

    Science.gov (United States)

    Vongsvivut, Jitraporn; Truong, Vi Khanh; Al Kobaisi, Mohammad; Maclaughlin, Shane; Tobin, Mark J; Crawford, Russell J; Ivanova, Elena P

    2017-01-01

    Surface modification of polymers and paints is a popular and effective way to enhance the properties of these materials. This can be achieved by introducing a thin coating that preserves the bulk properties of the material, while protecting it from environmental exposure. Suitable materials for such coating technologies are inorganic oxides, such as alumina, titania and silica; however, the fate of these materials during long-term environmental exposure is an open question. In this study, polymer coatings that had been enhanced with the addition of silica nanoparticles (SiO2NPs) and subsequently subjected to environmental exposure, were characterized both before and after the exposure to determine any structural changes resulting from the exposure. High-resolution synchrotron macro ATR-FTIR microspectroscopy and surface topographic techniques, including optical profilometry and atomic force microscopy (AFM), were used to determine the long-term effect of the environment on these dual protection layers after 3 years of exposure to tropical and sub-tropical climates in Singapore and Queensland (Australia). Principal component analysis (PCA) based on the synchrotron macro ATR-FTIR spectral data revealed that, for the 9% (w/w) SiO2NP/polymer coating, a clear discrimination was observed between the control group (no environmental exposure) and those samples subjected to three years of environmental exposure in both Singapore and Queensland. The PCA loading plots indicated that, over the three year exposure period, a major change occurred in the triazine ring vibration in the melamine resins. This can be attributed to the triazine ring being very sensitive to hydrolysis under the high humidity conditions in tropical/sub-tropical environments. This work provides the first direct molecular evidence, acquired using a high-resolution mapping technique, of the climate-induced chemical evolution of a polyester coating. The observed changes in the surface topography of the

  20. PHOTOMETRIC STEREO SHAPE-AND-ALBEDO-FROM-SHADING FOR PIXEL-LEVEL RESOLUTION LUNAR SURFACE RECONSTRUCTION

    Directory of Open Access Journals (Sweden)

    W. C. Liu

    2017-07-01

    Full Text Available Shape and Albedo from Shading (SAfS techniques recover pixel-wise surface details based on the relationship between terrain slopes, illumination and imaging geometry, and the energy response (i.e., image intensity captured by the sensing system. Multiple images with different illumination geometries (i.e., photometric stereo can provide better SAfS surface reconstruction due to the increase in observations. Photometric stereo SAfS is suitable for detailed surface reconstruction of the Moon and other extra-terrestrial bodies due to the availability of photometric stereo and the less complex surface reflecting properties (i.e., albedo of the target bodies as compared to the Earth. Considering only one photometric stereo pair (i.e., two images, pixel-variant albedo is still a major obstacle to satisfactory reconstruction and it needs to be regulated by the SAfS algorithm. The illumination directional difference between the two images also becomes an important factor affecting the reconstruction quality. This paper presents a photometric stereo SAfS algorithm for pixel-level resolution lunar surface reconstruction. The algorithm includes a hierarchical optimization architecture for handling pixel-variant albedo and improving performance. With the use of Lunar Reconnaissance Orbiter Camera - Narrow Angle Camera (LROC NAC photometric stereo images, the reconstructed topography (i.e., the DEM is compared with the DEM produced independently by photogrammetric methods. This paper also addresses the effect of illumination directional difference in between one photometric stereo pair on the reconstruction quality of the proposed algorithm by both mathematical and experimental analysis. In this case, LROC NAC images under multiple illumination directions are utilized by the proposed algorithm for experimental comparison. The mathematical derivation suggests an illumination azimuthal difference of 90 degrees between two images is recommended to achieve

  1. Near-UV radiation acts as a beneficial factor for physiological responses in cucumber plants.

    Science.gov (United States)

    Mitani-Sano, Makiko; Tezuka, Takafumi

    2013-11-05

    Effects of near-UV radiation on the growth and physiological activity of cucumber plants were investigated morphologically, physiologically and biochemically using 3-week-old seedlings grown under polyvinyl chloride films featuring transmission either above 290 nm or above 400 nm in growth chambers. The hypocotyl length and leaf area of cucumber seedlings were reduced but the thickness of leaves was enhanced by near-UV radiation, due to increased upper/lower epidermis thickness, palisade parenchyma thickness and volume of palisade parenchyma cells. Photosynthetic and respiratory activities were also promoted by near-UV radiation, associated with general enhancement of physiological/biochemical responses. Particularly, metabolic activities in the photosynthetic system of chloroplasts and the respiratory system of mitochondria were analyzed under the conditions of visible light with and without near-UV radiation. For example, the activities of NAD(P)-dependent enzymes such as glyceraldehyde-3-phosphate dehydrogenase (G3PDH) in chloroplasts and isocitrate dehydrogenase (ICDH) in mitochondria were elevated, along with levels of pyridine nucleotides (nicotinamide coenzymes) [NAD(H) and NADP(H)] and activity of NAD kinase (NADP forming enzyme). Taken together, these data suggest that promotion of cucumber plant growth by near-UV radiation involves activation of carbon and nitrogen metabolism in plants. The findings of this research showed that near-UV radiation reaching the Earth's surface is a beneficial factor for plant growth. Copyright © 2013. Published by Elsevier B.V.

  2. UV disinfection of water

    International Nuclear Information System (INIS)

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

    1978-01-01

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

  3. Optimizing UV Index determination from broadband irradiances

    Science.gov (United States)

    Tereszchuk, Keith A.; Rochon, Yves J.; McLinden, Chris A.; Vaillancourt, Paul A.

    2018-03-01

    A study was undertaken to improve upon the prognosticative capability of Environment and Climate Change Canada's (ECCC) UV Index forecast model. An aspect of that work, and the topic of this communication, was to investigate the use of the four UV broadband surface irradiance fields generated by ECCC's Global Environmental Multiscale (GEM) numerical prediction model to determine the UV Index. The basis of the investigation involves the creation of a suite of routines which employ high-spectral-resolution radiative transfer code developed to calculate UV Index fields from GEM forecasts. These routines employ a modified version of the Cloud-J v7.4 radiative transfer model, which integrates GEM output to produce high-spectral-resolution surface irradiance fields. The output generated using the high-resolution radiative transfer code served to verify and calibrate GEM broadband surface irradiances under clear-sky conditions and their use in providing the UV Index. A subsequent comparison of irradiances and UV Index under cloudy conditions was also performed. Linear correlation agreement of surface irradiances from the two models for each of the two higher UV bands covering 310.70-330.0 and 330.03-400.00 nm is typically greater than 95 % for clear-sky conditions with associated root-mean-square relative errors of 6.4 and 4.0 %. However, underestimations of clear-sky GEM irradiances were found on the order of ˜ 30-50 % for the 294.12-310.70 nm band and by a factor of ˜ 30 for the 280.11-294.12 nm band. This underestimation can be significant for UV Index determination but would not impact weather forecasting. Corresponding empirical adjustments were applied to the broadband irradiances now giving a correlation coefficient of unity. From these, a least-squares fitting was derived for the calculation of the UV Index. The resultant differences in UV indices from the high-spectral-resolution irradiances and the resultant GEM broadband irradiances are typically within 0

  4. Effects of UV irradiation on a living skin equivalent

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, D; Gay, R J [Organogenesis Incorporated, Camton, MA (United States)

    1993-05-01

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

  5. Effects of UV irradiation on a living skin equivalent

    International Nuclear Information System (INIS)

    Nelson, D.; Gay, R.J.

    1993-01-01

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

  6. A high resolution photoemission study of surface core-level shifts in clean and oxygen-covered Ir(2 1 0) surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Gladys, M.J.; Ermanoski, I.; Jackson, G.; Quinton, J.S.; Rowe, J.E.; Madey, T.E. E-mail: madey@physics.rutgers.edu

    2004-04-01

    High resolution soft X-ray photoemission electron spectroscopy (SXPS), using synchrotron radiation, is employed to investigate 4f core-level features of four differently-prepared Ir(2 1 0) surfaces: clean planar, oxygen-covered planar, oxygen-induced faceted, and clean faceted surfaces. Surface and bulk peak identifications are supported by measurements at different photon energies (thus probing different electron escape depths) and variable emission angles. Iridium 4f{sub 7/2} photoemission spectra are fitted with Doniach-Sunjic lineshapes. The surface components are identified with core levels positioned at lower binding energies than the bulk components, in contrast to previous reports of binding energy inversion on Ir(1 0 0) (1x1) and (5x1) surfaces. For clean planar Ir(2 1 0) three surface Ir 4f{sub 7/2} features are observed with core-level shifts of -765, -529, and -281 meV, with respect to the bulk; these are associated with the first, second and third layers of atoms, respectively, for atomically rough Ir(2 1 0). Adsorption of oxygen onto the planar Ir(2 1 0) surface is found to cause a suppression and shift of the surface features to higher binding energies. Annealing at T{>=}600 K in oxygen produces a faceted surface as verified by low energy electron diffraction (LEED). A comparison of planar and faceted oxygen-covered surfaces reveals minor differences in the normal emission SXPS spectra, while grazing emission spectra exhibit differences. The SXPS spectrum of the clean, faceted Ir(2 1 0) exhibits small differences in comparison to the clean planar case, with surface features having binding energy shifts of -710, -450, and -230 meV.

  7. Identification of new fluorescence processes in the UV spectra of cool stars from new energy levels of Fe II and Cr II

    Science.gov (United States)

    Johansson, Sveneric; Carpenter, Kenneth G.

    1988-01-01

    Two fluorescence processes operating in atmospheres of cool stars, symbiotic stars, and the Sun are presented. Two emission lines, at 1347.03 and 1360.17 A, are identified as fluorescence lines of Cr II and Fe II. The lines are due to transitions from highly excited levels, which are populated radiatively by the hydrogen Lyman alpha line due to accidental wavelength coincidences. Three energy levels, one in Cr II and two in Fe II, are reported.

  8. Simple Response Surface Methodology: Investigation on Advance Photocatalytic Oxidation of 4-Chlorophenoxyacetic Acid Using UV-Active ZnO Photocatalyst.

    Science.gov (United States)

    Lee, Kian Mun; Hamid, Sharifah Bee Abd

    2015-01-19

    The performance of advance photocatalytic degradation of 4-chlorophenoxyacetic acid (4-CPA) strongly depends on photocatalyst dosage, initial concentration and initial pH. In the present study, a simple response surface methodology (RSM) was applied to investigate the interaction between these three independent factors. Thus, the photocatalytic degradation of 4-CPA in aqueous medium assisted by ultraviolet-active ZnO photocatalyst was systematically investigated. This study aims to determine the optimum processing parameters to maximize 4-CPA degradation. Based on the results obtained, it was found that a maximum of 91% of 4-CPA was successfully degraded under optimal conditions (0.02 g ZnO dosage, 20.00 mg/L of 4-CPA and pH 7.71). All the experimental data showed good agreement with the predicted results obtained from statistical analysis.

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

    Directory of Open Access Journals (Sweden)

    I. Ialongo

    2011-09-01

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

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

  10. Interdependence between body surface area and ultraviolet B dose in vitamin D production

    DEFF Research Database (Denmark)

    Bogh, M K B; Schmedes, Anne; Philipsen, P A

    2011-01-01

    Ultraviolet (UV) B radiation increases serum vitamin D level expressed as 25-hydroxyvitamin-D(3) [25(OH)D], but the relationship to body surface area and UVB dose needs investigation.......Ultraviolet (UV) B radiation increases serum vitamin D level expressed as 25-hydroxyvitamin-D(3) [25(OH)D], but the relationship to body surface area and UVB dose needs investigation....

  11. Observations of the structure and evolution of surface and flight-level wind asymmetries in Hurricane Rita (2005)

    Science.gov (United States)

    Rogers, Robert; Uhlhorn, Eric

    2008-11-01

    Knowledge of the magnitude and distribution of surface winds, including the structure of azimuthal asymmetries in the wind field, are important factors for tropical cyclone forecasting. With its ability to remotely measure surface wind speeds, the stepped frequency microwave radiometer (SFMR) has assumed a prominent role for the operational tropical cyclone forecasting community. An example of this instrument's utility is presented here, where concurrent measurements of aircraft flight-level and SFMR surface winds are used to document the wind field evolution over three days in Hurricane Rita (2005). The amplitude and azimuthal location (phase) of the wavenumber-1 asymmetry in the storm-relative winds varied at both levels over time. The peak was found to the right of storm track at both levels on the first day. By the third day, the peak in flight-level storm-relative winds remained to the right of storm track, but it shifted to left of storm track at the surface, resulting in a 60-degree shift between the surface and flight-level and azimuthal variations in the ratio of surface to flight-level winds. The asymmetric differences between the surface and flight-level maximum wind radii also varied, indicating a vortex whose tilt was increasing.

  12. Changes induced by UV radiation in the presence of sodium benzoate in films formulated with polyvinyl alcohol and carboxymethyl cellulose

    Energy Technology Data Exchange (ETDEWEB)

    Villarruel, S. [Faculty of Exact Sciences, UNLP (Argentina); Giannuzzi, L.; Rivero, S. [Center for Research and Development in Food Cryotechnology (CCT-CONICET La Plata), 47 and 116 (Argentina); Pinotti, A., E-mail: acaimpronta@hotmail.com [Center for Research and Development in Food Cryotechnology (CCT-CONICET La Plata), 47 and 116 (Argentina); Faculty of Engineering, UNLP, La Plata 1900 (Argentina)

    2015-11-01

    This work was focused on: i) developing single and blend films based on carboxymethyl cellulose (CMC) and polyvinyl alcohol (PVOH) studying their properties, ii) analyzing the interactions between CMC and PVOH and their modifications UV-induced in the presence of sodium benzoate (SB), and iii) evaluating the antimicrobial capacity of blend films containing SB with and without UV treatment. Once the blend films with SB were exposed to UV radiation, they exhibited lower moisture content as well as a greater elongation at break and rougher surfaces compared to those without treatment. Considering oxygen barrier properties, the low values obtained would allow their application as packaging with selective oxygen permeability. Moreover, the characteristics of the amorphous phase of the matrix prevailed with a rearrangement of the structure of the polymer chain, causing a decrease of the crystallinity degree. These results were supported by X-rays and DSC analysis. FT-IR spectra reflected some degree of polymer–polymer interaction at a molecular level in the amorphous regions. The incorporation of sodium benzoate combined with UV treatment in blend films was positive from the microbial point of view because of the growth inhibition of a wide spectrum of microorganisms. From a physicochemical perspective, the UV treatment of films also changed their morphology rendering them more insoluble in water, turning the functionalized blend films into a potential material to be applied as food packaging. - Highlights: • CMC:PVOH blend films were developed with the addition of sodium benzoate (SB). • Exposition to UV radiation was carried out with sodium benzoate as photoinitiator. • Blend films were exposed to UV radiation to modify their surface morphology. • Low O{sub 2} permeability of UV treated blends allow them to be used as selective packaging. • Efficacy of SB as an antimicrobial agent was examined with and without UV radiation.

  13. Changes induced by UV radiation in the presence of sodium benzoate in films formulated with polyvinyl alcohol and carboxymethyl cellulose

    International Nuclear Information System (INIS)

    Villarruel, S.; Giannuzzi, L.; Rivero, S.; Pinotti, A.

    2015-01-01

    This work was focused on: i) developing single and blend films based on carboxymethyl cellulose (CMC) and polyvinyl alcohol (PVOH) studying their properties, ii) analyzing the interactions between CMC and PVOH and their modifications UV-induced in the presence of sodium benzoate (SB), and iii) evaluating the antimicrobial capacity of blend films containing SB with and without UV treatment. Once the blend films with SB were exposed to UV radiation, they exhibited lower moisture content as well as a greater elongation at break and rougher surfaces compared to those without treatment. Considering oxygen barrier properties, the low values obtained would allow their application as packaging with selective oxygen permeability. Moreover, the characteristics of the amorphous phase of the matrix prevailed with a rearrangement of the structure of the polymer chain, causing a decrease of the crystallinity degree. These results were supported by X-rays and DSC analysis. FT-IR spectra reflected some degree of polymer–polymer interaction at a molecular level in the amorphous regions. The incorporation of sodium benzoate combined with UV treatment in blend films was positive from the microbial point of view because of the growth inhibition of a wide spectrum of microorganisms. From a physicochemical perspective, the UV treatment of films also changed their morphology rendering them more insoluble in water, turning the functionalized blend films into a potential material to be applied as food packaging. - Highlights: • CMC:PVOH blend films were developed with the addition of sodium benzoate (SB). • Exposition to UV radiation was carried out with sodium benzoate as photoinitiator. • Blend films were exposed to UV radiation to modify their surface morphology. • Low O 2 permeability of UV treated blends allow them to be used as selective packaging. • Efficacy of SB as an antimicrobial agent was examined with and without UV radiation

  14. Statistical characterization of global Sea Surface Salinity for SMOS level 3 and 4 products

    Science.gov (United States)

    Gourrion, J.; Aretxabaleta, A. L.; Ballabrera, J.; Mourre, B.

    2009-04-01

    The Soil Moisture and Ocean Salinity (SMOS) mission of the European Space Agency will soon provide sea surface salinity (SSS) estimates to the scientific community. Because of the numerous geophysical contamination sources and the instrument complexity, the salinity products will have a low signal to noise ratio at level 2 (individual estimates??) that is expected to increase up to mission requirements (0.1 psu) at level 3 (global maps with regular distribution) after spatio-temporal accumulation of the observations. Geostatistical methods such as Optimal Interpolation are being implemented at the level 3/4 production centers to operate this noise reduction step. The methodologies require auxiliary information about SSS statistics that, under Gaussian assumption, consist in the mean field and the covariance of the departures from it. The present study is a contribution to the definition of the best estimates for mean field and covariances to be used in the near-future SMOS level 3 and 4 products. We use complementary information from sparse in-situ observations and imperfect outputs from state-of-art model simulations. Various estimates of the mean field are compared. An alternative is the use of a SSS climatology such as the one provided by the World Ocean Atlas 2005. An historical SSS dataset from the World Ocean Database 2005 is reanalyzed and combined with the recent global observations obtained by the Array for Real-Time Geostrophic Oceanography (ARGO). Regional tendencies in the long-term temporal evolution of the near-surface ocean salinity are evident, suggesting that the use of a SSS climatology to describe the current mean field may introduce biases of magnitude similar to the precision goal. Consequently, a recent SSS dataset may be preferred to define the mean field needed for SMOS level 3 and 4 production. The in-situ observation network allows a global mapping of the low frequency component of the variability, i.e. decadal, interannual and seasonal

  15. Functional levels of floor surface roughness for the prevention of slips and falls: clean-and-dry and soapsuds-covered wet surfaces.

    Science.gov (United States)

    Kim, In-Ju; Hsiao, Hongwei; Simeonov, Peter

    2013-01-01

    Literature has shown a general trend that slip resistance performance improves with floor surface roughness. However, whether slip resistance properties are linearly correlated with surface topographies of the floors or what roughness levels are required for effective slip resistance performance still remain to be answered. This pilot study aimed to investigate slip resistance properties and identify functional levels of floor surface roughness for practical design applications in reducing the risk of slip and fall incidents. A theory model was proposed to characterize functional levels of surface roughness of floor surfaces by introducing a new concept of three distinctive zones. A series of dynamic friction tests were conducted using 3 shoes and 9 floor specimens under clean-and-dry as well as soapsuds-covered slippery wet environments. The results showed that all the tested floor-shoe combinations provided sufficient slip resistances performance under the clean-and-dry condition. A significant effect of floor type (surface roughness) on dynamic friction coefficient (DFC) was found in the soapsuds-covered wet condition. As compared to the surface roughness effects, the shoe-type effects were relatively small. Under the soapsuds-covered wet condition, floors with 50 μm in Ra roughness scale seemed to represent an upper bound in the functional range of floor surface roughness for slip resistance because further increase of surface roughness provided no additional benefit. A lower bound of the functional range for slip resistance under the soapsuds-covered wet condition was estimated from the requirement of DFC > 0.4 at Ra ≅ 17 μm. Findings from this study may have potential safety implications in the floor surface design for reducing slip and fall hazards. Published by Elsevier Ltd.

  16. Improving Limit Surface Search Algorithms in RAVEN Using Acceleration Schemes: Level II Milestone

    Energy Technology Data Exchange (ETDEWEB)

    Alfonsi, Andrea [Idaho National Laboratory (INL), Idaho Falls, ID (United States); Rabiti, Cristian [Idaho National Laboratory (INL), Idaho Falls, ID (United States); Mandelli, Diego [Idaho National Laboratory (INL), Idaho Falls, ID (United States); Cogliati, Joshua Joseph [Idaho National Laboratory (INL), Idaho Falls, ID (United States); Sen, Ramazan Sonat [Idaho National Laboratory (INL), Idaho Falls, ID (United States); Smith, Curtis Lee [Idaho National Laboratory (INL), Idaho Falls, ID (United States)

    2015-07-01

    , subject of the analysis. These methodologies are named, in the RAVEN environment, adaptive sampling strategies. These methodologies infer system responses from surrogate models constructed from already existing samples (produced using high fidelity simulations) and suggest the most relevant location (coordinate in the input space) of the next sampling point to be explored in the uncertain/parametric domain. When using those methodologies, it is possible to understand features of the system response with a small number of carefully selected samples. This report focuses on the development and improvement of the limit surface search. The limit surface is an important concept in system reliability analysis. Without going into the details, which will be covered later in the report, the limit surface could be briefly described as an hyper-surface in the system uncertainty/parametric space separating the regions leading to a prescribed system outcome. For example, if the uncertainty/parametric space is the one generated by the reactor power level and the duration of the batteries, the system is a nuclear power plant and the system outcome discriminating variable is the clad failure in a station blackout scenario, then the limit surface separates the combinations of reactor power level and battery duration that lead to clad failure from the ones that do not.

  17. OMI/Aura Level 1B UV Global Geolocated Earthshine Radiances 1-orbit L2 Swath 13x24 km V003

    Data.gov (United States)

    National Aeronautics and Space Administration — The Level-1B (L1B) Radiance Product OML1BRUG (Version-3) from the Aura-OMI is now available to public (http://disc.gsfc.nasa.gov/Aura/OMI/oml1brug_v003.shtml) from...

  18. OMI/Aura Level 1B UV Zoom-in Geolocated Earthshine Radiances 1-orbit L2 Swath 13x12 km V003

    Data.gov (United States)

    National Aeronautics and Space Administration — The Level-1B (L1B) Radiance Product OML1BRUZ (Version-3) from the Aura-OMI is now available (http://disc.gsfc.nasa.gov/Aura/OMI/oml1bruz_v003.shtml) to public from...

  19. Localized surface plasmon enhanced deep UV-emitting of AlGaN based multi-quantum wells by Al nanoparticles on SiO2 dielectric interlayer

    Science.gov (United States)

    He, Ju; Wang, Shuai; Chen, Jingwen; Wu, Feng; Dai, Jiangnan; Long, Hanling; Zhang, Yi; Zhang, Wei; Feng, Zhe Chuan; Zhang, Jun; Du, Shida; Ye, Lei; Chen, Changqing

    2018-05-01

    In this paper, we report a 2.6-fold deep ultraviolet emission enhancement of integrated photoluminescence (PL) intensity in AlGaN-based multi-quantum wells (MQWs) by introducing the coupling of local surface plasmons from Al nanoparticles (NPs) on a SiO2 dielectric interlayer with excitons and photons in MQWs at room temperature. In comparison to bare AlGaN MQWs, a significant 2.3-fold enhancement of the internal quantum efficiency, from 16% to 37%, as well as a 13% enhancement of photon extraction efficiency have been observed in the MQWs decorated with Al NPs on SiO2 dielectric interlayer. Polarization-dependent PL measurement showed that both the transverse electric and transverse magnetic mode were stronger than the original intensity in bare AlGaN MQWs, indicating a strong LSPs coupling process and vigorous scattering ability of the Al/SiO2 composite structure. These results were confirmed by the activation energy of non-radiative recombination from temperature-dependent PL measurement and the theoretical three dimensional finite difference time domain calculations.

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

    Directory of Open Access Journals (Sweden)

    Uwe Feister

    2015-08-01

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

  1. Composite Fermi surface in the half-filled Landau level with anisotropic electron mass

    Science.gov (United States)

    Ippoliti, Matteo; Geraedts, Scott; Bhatt, Ravindra

    We study the problem of interacting electrons in the lowest Landau level at half filling in the quantum Hall regime, when the electron dispersion is given by an anisotropic mass tensor. Based on experimental observations and theoretical arguments, the ground state of the system is expected to consist of composite Fermions filling an elliptical Fermi sea, with the anisotropy of the ellipse determined by the competing effects of the isotropic Coulomb interaction and anisotropic electron mass tensor. We test this idea quantitatively by using a numerical density matrix renormalization group method for quantum Hall systems on an infinitely long cylinder. Singularities in the structure factor allow us to map the Fermi surface of the composite Fermions. We compute the composite Fermi surface anisotropy for several values of the electron mass anisotropy which allow us to deduce the functional dependence of the former on the latter. This research was supported by Department of Energy Office of Basic Energy Sciences through Grant No. DE-SC0002140.

  2. Facet personality and surface-level diversity as team mental model antecedents: implications for implicit coordination.

    Science.gov (United States)

    Fisher, David M; Bell, Suzanne T; Dierdorff, Erich C; Belohlav, James A

    2012-07-01

    Team mental models (TMMs) have received much attention as important drivers of effective team processes and performance. Less is known about the factors that give rise to these shared cognitive structures. We examined potential antecedents of TMMs, with a specific focus on team composition variables, including various facets of personality and surface-level diversity. Further, we examined implicit coordination as an important outcome of TMMs. Results suggest that team composition in terms of the cooperation facet of agreeableness and racial diversity were significantly related to team-focused TMM similarity. TMM similarity was also positively predictive of implicit coordination, which mediated the relationship between TMM similarity and team performance. Post hoc analyses revealed a significant interaction between the trust facet of agreeableness and racial diversity in predicting TMM similarity. Results are discussed in terms of facilitating the emergence of TMMs and corresponding implications for team-related human resource practices. (PsycINFO Database Record (c) 2012 APA, all rights reserved).

  3. Selection of replacement material for the failed surface level gauge wire in Hanford waste tanks

    International Nuclear Information System (INIS)

    Anantatmula, R.P.; Pitman, S.G.; Lund, A.L.

    1995-10-01

    Surface level gauges fabricated from AISI Type 316 stainless steel (316) wire failed after only a few weeks of operation in underground storage tanks at the Hanford Site. The wire failure was determined to be due to chloride ion assisted corrosion of the 316 wire. Radiation-induced breakdown of the polyvinyl chloride (PVC) riser liners is suspected to be the primary source of the chloride ions. An extensive literature search followed by expert concurrence was undertaken to select a replacement material for the wire. Platinum (Pt)-20 % Iridium (Ir) alloy was selected as the replacement material from tile candidate materials, P-20% Ir, Pt-1O% Rhodium (Rh), Pt-20%Rh and Hastelloy C-22. The selection was made on the basis of the alloy's immunity towards acidic and basic environments as well as its adequate tensile properties in the fully annealed state

  4. Energy pumping analysis of skating motion in a half pipe and on a level surface

    Science.gov (United States)

    Feng, Z. C.; Xin, Ming

    2015-01-01

    In this paper, an energy pumping mechanism for locomotion is analysed. The pumping is accomplished by exerting forces perpendicular to the direction of motion. The paper attempts to demonstrate an interesting application of the classical mechanics to two sporting events: a person skating in a half pipe and a person travelling on a level surface on a skateboard. The equations of motion based on simplified mechanical models are derived using the Lagrange mechanics. The energy-pumping phenomenon is revealed through numerical simulations with simple pumping actions. The result presented in this paper can be used as an interesting class project in undergraduate mechanics or physics courses. It also motivates potential new applications of energy pumping in many engineering fields.

  5. Energy pumping analysis of skating motion in a half pipe and on a level surface

    International Nuclear Information System (INIS)

    Feng, Z C; Xin, Ming

    2015-01-01

    In this paper, an energy pumping mechanism for locomotion is analysed. The pumping is accomplished by exerting forces perpendicular to the direction of motion. The paper attempts to demonstrate an interesting application of the classical mechanics to two sporting events: a person skating in a half pipe and a person travelling on a level surface on a skateboard. The equations of motion based on simplified mechanical models are derived using the Lagrange mechanics. The energy-pumping phenomenon is revealed through numerical simulations with simple pumping actions. The result presented in this paper can be used as an interesting class project in undergraduate mechanics or physics courses. It also motivates potential new applications of energy pumping in many engineering fields. (paper)

  6. Scientific and technical basis for the near surface disposal of low and intermediate level waste

    International Nuclear Information System (INIS)

    2002-01-01

    This report presents an overview of the scientific and technical basis for the disposal of low- and intermediate-level radioactive waste in near surface repositories. The focus is on basic principles, approaches, methodologies and technical criteria that can be used to develop and assess the performance of a disposal facility, and for building confidence in repository safety. This includes consideration of the multiple barrier concept, the performance of engineered barriers, the role of natural barriers and the development of a safety case. The emphasis is on defining the conditions relevant to the containment of the radionuclides in the repository and the processes that may affect the integrity of the engineered barriers. Both generic and specific data requirements for repository development and the assurance of safety are addressed. A large number of bibliographical references are given to support the information provided in this report

  7. Evaluation of pressure transducers to measure surface level in the waste storage tanks

    International Nuclear Information System (INIS)

    Peters, T.J.; Colson, J.B.

    1994-06-01

    This report describes the results of tests conducted at the Pacific Northwest Laboratory (PNL) to determine if pressure transducers can be used to measure the surface level in the waste tanks. A survey was first conducted to evaluate which, if any, commercially available pressure transducers were available that could meet the requirements for use in the waste tanks. More than 35 companies were contacted to determine if they manufactured a pressure transducer that could be used in the 101-SY waste tank. The three basic requirements for a pressure transducer for this application were that they were radiation-hardened, could withstand a caustic environment, and were certified to be intrinsically safe. No manufacturer was able to meet all three of these requirements with a commercially available product. Seven companies were able to meet the requirements for being radiation-hardened and being able to withstand the caustic environment. However, only two of the nine companies were willing to supply a pressure transducer for laboratory testing. The two pressure transducers that were tested in this program were the VEGA D36-38 from HiTech Technologies, Inc., and the KP-1911-A from Kaman Instrumentation Corporation. Pressure transducers operate on the principle that the pressure at the location of a sensor increases directly with the depth of the liquid above it. A liquid is required in order for these devices to operate. For these tests, water was first used to determine the ideal operation of the devices, then the devices were placed in a 101-SY waste tank simulant. The simulant had a specific gravity of 1.96 and had the consistency similar to the convective layer in the 101-SY waste tank. In order to determine the surface level with pressure transducers, the density of the material needs to be known

  8. In vivo activation of human immunodeficiency virus type 1 long terminal repeat by UV type A (UV-A) light plus psoralen and UV-B light in the skin of transgenic mice

    OpenAIRE

    Morrey, John D; Bourn, S M; Bunch, T D; Jackson, M K; Sidwell, R W; Barrows, L R; Daynes, R A; Rosen, C A

    1991-01-01

    UV irradiation has been shown to activate the human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR) in cell culture; however, only limited studies have been described in vivo. UV light has been categorized as UV-A (400 to 315 nm), -B (315 to 280 nm), or -C (less than 280 nm); the longer wavelengths are less harmful but more penetrative. Highly penetrative UV-A radiation constitutes the vast majority of UV sunlight reaching the earth's surface but is normally harmless. UV-B ir...

  9. Near-surface storage facilities for vitrified high-level wastes

    International Nuclear Information System (INIS)

    Kondrat'ev, A.N.; Kulichenko, V.V.; Kryukov, I.I.; Krylova, N.V.; Paramoshkin, V.I.; Strakhov, M.V.

    1980-01-01

    Concurrently with the development of methods for solidifying liquid radioactive wastes, reliable and safe methods for the storage and disposal of solidified wastes are being devised in the USSR and other countries. One of the main factors affecting the choice of storage conditions for solidified wastes originating from the vitrification of high-level liquid wastes from fuel reprocessing plants is the problem of removing the heat produced by radioactive decay. In order to prevent the temperature of solidified wastes from exceeding the maximum permissible level for the material concerned, it is necessary to limit either the capacity of waste containers or the specific heat release of the wastes themselves. In order that disposal of high-level wastes in geological formations should be reliable and economic, solidified wastes undergo interim storage in near-surface storage facilities with engineered cooling systems. The paper demonstrates the relative influences of specific heat release, of the maximum permissible storage temperature for vitrified wastes and of the methods chosen for cooling wastes in order for the dimensions of waste containers to be reduced to the extent required. The effect of concentrating wastes to a given level in the vitrification process on the cost of storage in different types of storage facility is also examined. Calculations were performed for the amount of vitrified wastes produced by a reprocessing plant with a capacity of five tonnes of uranium per 24 hours. Fuel elements from reactors of the water-cooled, water-moderated type are sent for reprocessing after having been held for about two years. The dimensions of the storage facility are calculated on the assumption that it will take five years to fill

  10. DNA degradation, UV sensitivity and SOS-mediated mutagenesis in strains of Escherichia coli deficient in single-strand DNA binding protein: Effects of mutations and treatments that alter levels of exonuclease V or RecA protein

    International Nuclear Information System (INIS)

    Lieberman, H.B.; Witkin, E.M.

    1983-01-01

    Certain strains suppress the temperature-sensitivity caused by ssb-1, which encodes a mutant ssDNA binding protein (SSB). At 42 0 C, such strains are extremely UV-sensitive, degrade their DNA extensively after UV irradiation, and are defficient in UV mutability and UV induction of recA protein synthesis. We transduced recC22, which eliminates Exonuclease V activity, and recAo281, which causes operator-constitutive synthesis of recA protein, into such an ssb-1 strain. Both double mutants degraded their DNA extensively at 42 0 C after UV irradiation, and both were even more UV-sensitive than the ssb-1 single mutant. We conclude that one or more nucleases other than Exonuclease V degrades DNA in the ssb recC strain, and that recA protein, even if synthesized copiously, can function efficiently in recombinational DNA repair and in control of post-UV DNA degradation only if normal SSB is also present. Pretreatment with nalidixic acid at 30 0 C restored normal UV mutability at 42 0 C, but did not increase UV resistance, in an ssb-1 strain. Another ssb allele, ssb-113, which blocks SOS induction at 30 0 C, increases spontaneous mutability more than tenfold. The ssb-113 allele was transduced into the SOS-constitutive recA730 strain SC30. This double mutant expressed the same elevated spontaneous and UV-induced mutability at 30 0 C as the ssb + recA730 strain, and was three times more UV-resistant than its ssb-113 recA + parent. We conclude that ssb-1 at 42 0 C and ssb-113 at 30 0 C block UV-induced activation of recA protease, but that neither allele interferes with subsequent steps in SOS-mediated mutagenesis. (orig.)

  11. Assessment of the SMAP Level-4 Surface and Root-Zone Soil Moisture Product Using In Situ Measurements

    NARCIS (Netherlands)

    Reichle, Rolf H.; De Lannoy, Gabrielle J. M.; Liu, Qing; Ardizzone, Joseph V.; Colliander, Andreas; Conaty, Austin; Crow, Wade; Jackson, Thomas J.; Jones, Lucas A.; Kimball, John S.; Koster, Randal D.; Mahanama, Sarith P.; Smith, Edmond B.; Berg, Aaron; Bircher, Simone; Bosch, David; Caldwell, Todd G.; Cosh, Michael; Holifield Collins, Chandra D.; Jensen, Karsten H.; Livingston, Stan; Lopez-baeza, Ernesto; Martínez-fernández, José; Mcnairn, Heather; Moghaddam, Mahta; Pacheco, Anna; Pellarin, Thierry; Prueger, John; Rowlandson, Tracy; Seyfried, Mark; Starks, Patrick; Su, Bob; Thibeault, Marc; Van Der Velde, Rogier; Walker, Jeffrey; Wu, Xiaoling; Zeng, Yijian

    2017-01-01

    The Soil Moisture Active Passive (SMAP) mission Level-4 Surface and Root-Zone Soil Moisture (L4_SM) data product is generated by assimilating SMAP L-band brightness temperature observations into the NASA Catchment land surface model. The L4_SM product is available from 31 March 2015 to present

  12. OMI/Aura Surface Reflectance Climatology Level 3 Global 0.5deg Lat/Lon Grid V003

    Data.gov (United States)

    National Aeronautics and Space Administration — The OMI Earth Surface Reflectance Climatology product, OMLER (Global 0.5deg Lat/Lon grid) which is based on Version 003 Level-1B top of atmosphere upwelling radiance...

  13. Genus- and species-level identification of dermatophyte fungi by surface-enhanced Raman spectroscopy

    Science.gov (United States)

    Witkowska, Evelin; Jagielski, Tomasz; Kamińska, Agnieszka

    2018-03-01

    This paper demonstrates that surface-enhanced Raman spectroscopy (SERS) coupled with principal component analysis (PCA) can serve as a fast and reliable technique for detection and identification of dermatophyte fungi at both genus and species level. Dermatophyte infections are the most common mycotic diseases worldwide, affecting a quarter of the human population. Currently, there is no optimal method for detection and identification of fungal diseases, as each has certain limitations. Here, for the first time, we have achieved with a high accuracy, differentiation of dermatophytes representing three major genera, i.e. Trichophyton, Microsporum, and Epidermophyton. Two first principal components (PC), namely PC-1 and PC-2, gave together 97% of total variance. Additionally, species-level identification within the Trichophyton genus has been performed. PC-1 and PC-2, which are the most diagnostically significant, explain 98% of the variance in the data obtained from spectra of: Trichophyton rubrum, Trichophyton menatgrophytes, Trichophyton interdigitale and Trichophyton tonsurans. This study offers a new diagnostic approach for the identification of dermatophytes. Being fast, reliable and cost-effective, it has the potential to be incorporated in the clinical practice to improve diagnostics of medically important fungi.

  14. A Continuous Liquid-Level Sensor for Fuel Tanks Based on Surface Plasmon Resonance

    Directory of Open Access Journals (Sweden)

    Antonio M. Pozo

    2016-05-01

    Full Text Available A standard problem in large tanks at oil refineries and petrol stations is that water and fuel usually occupy the same tank. This is undesirable and causes problems such as corrosion in the tanks. Normally, the water level in tanks is unknown, with the problems that this entails. We propose herein a method based on surface plasmon resonance (SPR to detect in real time the interfaces in a tank which can simultaneously contain water, gasoline (or diesel and air. The plasmonic sensor is composed of a hemispherical glass prism, a magnesium fluoride layer, and a gold layer. We have optimized the structural parameters of the sensor from the theoretical modeling of the reflectance curve. The sensor detects water-fuel and fuel-air interfaces and measures the level of each liquid in real time. This sensor is recommended for inflammable liquids because inside the tank there are no electrical or electronic signals which could cause explosions. The sensor proposed has a sensitivity of between 1.2 and 3.5 RIU−1 and a resolution of between 5.7 × 10−4 and 16.5 × 10−4 RIU.

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

    International Nuclear Information System (INIS)

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

    1990-01-01

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

  16. Comparisons of predicted steady-state levels in rooms with extended- and local-reaction bounding surfaces

    Science.gov (United States)

    Hodgson, Murray; Wareing, Andrew

    2008-01-01

    A combined beam-tracing and transfer-matrix model for predicting steady-state sound-pressure levels in rooms with multilayer bounding surfaces was used to compare the effect of extended- and local-reaction surfaces, and the accuracy of the local-reaction approximation. Three rooms—an office, a corridor and a workshop—with one or more multilayer test surfaces were considered. The test surfaces were a single-glass panel, a double-drywall panel, a carpeted floor, a suspended-acoustical ceiling, a double-steel panel, and glass fibre on a hard backing. Each test surface was modeled as of extended or of local reaction. Sound-pressure levels were predicted and compared to determine the significance of the surface-reaction assumption. The main conclusions were that the difference between modeling a room surface as of extended or of local reaction is not significant when the surface is a single plate or a single layer of material (solid or porous) with a hard backing. The difference is significant when the surface consists of multilayers of solid or porous material and includes a layer of fluid with a large thickness relative to the other layers. The results are partially explained by considering the surface-reflection coefficients at the first-reflection angles.

  17. Optimization of droplets for UV-NIL using coarse-grain simulation of resist flow

    Science.gov (United States)

    Sirotkin, Vadim; Svintsov, Alexander; Zaitsev, Sergey

    2009-03-01

    A mathematical model and numerical method are described, which make it possible to simulate ultraviolet ("step and flash") nanoimprint lithography (UV-NIL) process adequately even using standard Personal Computers. The model is derived from 3D Navier-Stokes equations with the understanding that the resist motion is largely directed along the substrate surface and characterized by ultra-low values of the Reynolds number. By the numerical approximation of the model, a special finite difference method is applied (a coarse-grain method). A coarse-grain modeling tool for detailed analysis of resist spreading in UV-NIL at the structure-scale level is tested. The obtained results demonstrate the high ability of the tool to calculate optimal dispensing for given stamp design and process parameters. This dispensing provides uniform filled areas and a homogeneous residual layer thickness in UV-NIL.

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

    Science.gov (United States)

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

    2017-12-01

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

  19. Occurrence and levels of polybrominated diphenyl ethers in surface sediments from the Yellow River Estuary, China.

    Science.gov (United States)

    Yuan, Zijiao; Liu, Guijian; Lam, Michael Hon Wah; Liu, Houqi; Da, Chunnian

    2016-05-01

    A total of 21 surface sediments collected from the Yellow River Estuary, China were analyzed for 40 kinds of polybrominated diphenyl ethers (PBDEs) using gas chromatography-mass spectrometry (GC-MS). Their levels, spatial distribution, congener profiles and possible sources were investigated. Only ten congeners were detected in the sediments. The total concentrations of the lower brominated BDEs (∑PBDEslow, PBDEs excluding BDE 209) and BDE 209 ranged from 0.482 ng/g to 1.07 ng/g and 1.16-5.40 ng/g, with an average value of 0.690 and 2.79 ng/g, respectively, which were both at the low end of the global contamination level. The congener profiles were dominated by BDE 209, with the average value accounting for 79.2% of the total PBDEs in the sediment samples. Among the nine lower brominated BDE congeners, BDE 47, 99 and 183 had high abundances. Although the commercial Penta/Octa-BDE products have been banned in most countries, the residual commercial Penta/Octa/Deca-BDE products and the debromination of highly brominated BDE compounds such as BDE 209 were still found to be the possible sources for the trace level of PBDEs in the present study area. In spite of the gradual removal of the commercial PBDEs in the world, the present research results further suggested that scientific attention should not be reduced on the issue of environmental contamination caused by these outdated chemical compounds. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Formation and removal of genotoxic activity during UV/H

    NARCIS (Netherlands)

    Heringa, M.B.; Harmsen, D.J.H.; Beerendonk, E.F.; Reus, A.A.; Krul, C.A.M.; Metz, D.H.; Ijpelaar, G.F.

    2011-01-01

    The objective of this study was to determine the genotoxic activity of water after UV/H2O2 oxidation and GAC filtration. Pre-treated surface water from three locations was treated with UV/H2O2 with medium pressure (MP) lamps and passed through granulated

  1. UV patterned nanoporous solid-liquid core waveguides

    DEFF Research Database (Denmark)

    Gopalakrishnan, Nimi; Sagar, Kaushal Shashikant; Christiansen, Mads Brøkner

    2010-01-01

    Nanoporous Solid-Liquid core waveguides were prepared by UV induced surface modification of hydrophobic nanoporous polymers. With this method, the index contrast (delta n = 0.20) is a result of selective water infiltration. The waveguide core is defined by UV light, rendering the exposed part...

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

    Science.gov (United States)

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

    2016-04-01

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

  3. The absence of Ser389 phosphorylation in p53 affects the basal gene expression level of many p53-dependent genes and alters the biphasic response to UV exposure in mouse embryonic fibroblasts

    NARCIS (Netherlands)

    Bruins, Wendy; Bruning, Oskar; Jonker, Martijs J.; Zwart, Edwin; van der Hoeven, Tessa V.; Pennings, Jeroen L. A.; Rauwerda, Han; de Vries, Annemieke; Breit, Timo M.

    2008-01-01

    Phosphorylation is important in p53-mediated DNA damage responses. After UV irradiation, p53 is phosphorylated specifically at murine residue Ser389. Phosphorylation mutant p53.S389A cells and mice show reduced apoptosis and compromised tumor suppression after UV irradiation. We investigated the

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-06-01

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

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

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  6. Strong compensation hinders the p-type doping of ZnO: a glance over surface defect levels

    Science.gov (United States)

    Huang, B.

    2016-07-01

    We propose a surface doping model of ZnO to elucidate the p-type doping and compensations in ZnO nanomaterials. With an N-dopant, the effects of N on the ZnO surface demonstrate a relatively shallow acceptor level in the band gap. As the dimension of the ZnO materials decreases, the quantum confinement effects will increase and render the charge transfer on surface to influence the shifting of Fermi level, by evidence of transition level changes of the N-dopant. We report that this can overwhelm the intrinsic p-type conductivity and transport of the ZnO bulk system. This may provide a possible route of using surface doping to modify the electronic transport and conductivity of ZnO nanomaterials.

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

    Science.gov (United States)

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

    2012-08-01

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

  8. He-Ne laser treatment improves the photosynthetic efficiency of wheat exposed to enhanced UV-B radiation

    International Nuclear Information System (INIS)

    Chen, Huize; Han, Rong

    2014-01-01

    The level of ultraviolet-B (UV-B) radiation on the Earth’s surface has increased due to depletion of the ozone layer. Here, we explored the effects of continuous wave He-Ne laser irradiation (632 nm, 5 mW mm –2 , 2 min d –1 ) on the physiological indexes of wheat seedlings exposed to enhanced UV-B radiation (10 KJ m –2 d –1 ) at the early growth stages. Wheat seedlings were irradiated with enhanced