Increased affinity of endothelial cells to NiTi using ultraviolet irradiation: An in vitro study.

PubMed

Tateshima, Satoshi; Kaneko, Naoki; Yamada, Masahiro; Duckwiler, Gary; Vinuela, Fernando; Ogawa, Takahiro

2018-04-01

Nickel-titanium alloy (NiTi) is one of the most popular materials used endovascularly because of its shape memory and superelasticity. The NiTi device needs to be covered by endothelial cells after being placed in the blood vessel to reduce ischemic complications. The objective of this study was to examine the impact of ultraviolet (UV) irradiation on the biocompatibility of NiTi surfaces with endothelial cells. NiTi sheets were treated with UV irradiation for 48 h and human aorta derived endothelial cells were used in this study. UV irradiation converted the NiTi surface to hydrophilic state and increased albumin adsorption. The number of endothelial cell migration, attachment, proliferation as well as their metabolic activity were significantly increased on UV treated NiTi. This study provides the first evidence of the photoactivation of NiTi surfaces by UV irradiation and demonstrates improved biocompatibility of UV-treated NiTi surfaces with vascular endothelial cells. These results suggest that UV irradiation may promote endothelialization of NiTi devices in blood vessels. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1034-1038, 2018. © 2017 Wiley Periodicals, Inc.

Inactivation of indigenous coliform bacteria in unfiltered surface water by ultraviolet light.

PubMed

Cantwell, Raymond E; Hofmann, Ron

2008-05-01

This study examined the potential for naturally occurring particles to protect indigenous coliform from ultraviolet (UV) disinfection in four surface waters. Tailing in the UV dose-response curve of the bacteria was observed in 3 of the 4 water samples after 1.3-2.6-log of log-linear inactivation, implying particle-related protection. The impact of particles was confirmed by comparing coliform UV inactivation data for parallel filtered (11 microm pore-size nylon filters) and unfiltered surface water. In samples from the Grand River (UVT: 65%/cm; 5.4 nephelometric turbidity units (NTU)) and the Rideau Canal (UVT: 60%/cm; 0.84 NTU), a limit of approximately 2.5 log inactivation was achieved in the unfiltered samples for a UV dose of 20 mJ/cm2 while both the filtered samples exhibited >3.4-log inactivation of indigenous coliform bacteria. The results suggest that particles as small as 11 microm, naturally found in surface water with low turbidity (<3NTU), are able to harbor indigenous coliform bacteria and offer protection from low-pressure UV light.

Incorporation of multiple cloud layers for ultraviolet radiation modeling studies

NASA Technical Reports Server (NTRS)

Charache, Darryl H.; Abreu, Vincent J.; Kuhn, William R.; Skinner, Wilbert R.

1994-01-01

Cloud data sets compiled from surface observations were used to develop an algorithm for incorporating multiple cloud layers into a multiple-scattering radiative transfer model. Aerosol extinction and ozone data sets were also incorporated to estimate the seasonally averaged ultraviolet (UV) flux reaching the surface of the Earth in the Detroit, Michigan, region for the years 1979-1991, corresponding to Total Ozone Mapping Spectrometer (TOMS) version 6 ozone observations. The calculated UV spectrum was convolved with an erythema action spectrum to estimate the effective biological exposure for erythema. Calculations show that decreasing the total column density of ozone by 1% leads to an increase in erythemal exposure by approximately 1.1-1.3%, in good agreement with previous studies. A comparison of the UV radiation budget at the surface between a single cloud layer method and a multiple cloud layer method presented here is discussed, along with limitations of each technique. With improved parameterization of cloud properties, and as knowledge of biological effects of UV exposure increase, inclusion of multiple cloud layers may be important in accurately determining the biologically effective UV budget at the surface of the Earth.

Influence of ultraviolet irradiation treatment on porcelain bond strength of titanium surfaces.

PubMed

Kumasaka, Tomonari; Ohno, Akinori; Hori, Norio; Hoshi, Noriyuki; Maruo, Katsuichiro; Kuwabara, Atsushi; Seimiya, Kazuhide; Toyoda, Minoru; Kimoto, Katsuhiko

2018-01-26

To determine the effect of titanium (Ti) surface modification by ultraviolet irradiation (UVI) on the bond strength between Ti and porcelain. Grade 2 Ti plates were allotted to five groups: sandblasted (SA), 15 min UVI (UV), SA+5 min UVI (SA+UV5), SA+10 min UVI (SA+UV10), and SA+15 min UVI (SA+UV15). After surface treatment, porcelain was added. A precious metal (MC) was used for comparison with Ti. The effects of 24-h storage at room temperature versus thermal cycling only at 5 and 55°C in water were evaluated. Subsequently, the tensile strength of each sample was tested. Data were analyzed using one-way analysis of variance and the Tukey test. In both the room temperature and thermal cycling groups, the MC and SA+15 min UVI samples showed significantly greater bond strengths than the other samples (p<0.05). UVI processing efficiently increases the bond strength between porcelain and the Ti surface.

Surface grafting of a thermoplastic polyurethane with methacrylic acid by previous plasma surface activation and by ultraviolet irradiation to reduce cell adhesion.

PubMed

Alves, P; Pinto, S; Kaiser, Jean-Pierre; Bruinink, Arie; de Sousa, Hermínio C; Gil, M H

2011-02-01

The material performance, in a biological environment, is mainly mediated by its surface properties and by the combination of chemical, physical, biological, and mechanical properties required, for a specific application. In this study, the surface of a thermoplastic polyurethane (TPU) material (Elastollan(®)1180A50) was activated either by plasma or by ultra-violet (UV) irradiation. After surface activation, methacrylic acid (MAA) was linked to the surface of TPU in order to improve its reactivity and to reduce cell adhesion. Grafted surfaces were evaluated by X-ray photoelectron spectroscopy (XPS), by atomic force microscopy (AFM) and by contact angle measurements. Blood compatibility studies and cell adhesion tests with human bone marrow cells (HBMC) were also performed. If was found that UV grafting method led to better results than the plasma activation method, since cell adhesion was reduced when methacrylic acid was grafted to the TPU surface by UV. Copyright © 2010 Elsevier B.V. All rights reserved.

Long-term lithium-ion battery performance improvement via ultraviolet light treatment of the graphite anode

DOE PAGES

An, Seong Jin; Li, Jianlin; Sheng, Yangping; ...

2016-01-01

Effects of ultraviolet (UV) light on dried graphite anodes were investigated in terms of the cycle life of lithium ion batteries. The time variations for the UV treatment were 0 (no treatment), 20, 40, and 60 minutes. UV-light-treated graphite anodes were assembled for cycle life tests in pouch cells with pristine Li 1.02Ni 0.50Mn 0.29Co 0.19O 2 (NMC 532) cathodes. UV treatment for 40 minutes resulted in the highest capacity retention and the lowest resistance after the cycle life testing. X-ray photoelectron spectroscopy (XPS) and contact angle measurements on the graphite anodes showed changes in surface chemistry and wetting aftermore » the UV treatment. XPS also showed increases in solvent products and decreases in salt products on the SEI surface when UV-treated anodes were used. In conclusion, the thickness of the surface films and their compositions on the anodes and cathodes were also estimated using survey scans and snapshots from XPS depth profiles.« less

[Effectiveness of eyeglasses for protection against ultraviolet rays].

PubMed

Sakamoto, Y; Kojima, M; Sasaki, K

1999-05-01

The relationship between eyeglass size and protection of the eye surface from the effects of solar ultraviolet (UV) rays was investigated. Solar UV rays irradiating the eye surface were measured on a mannequin which modeled the standard facial bone structure of a Japanese female. UV sensor chips (photo-sensitivity: 260-400 nm) were attached to the ocular surface of the lid fissure. UV measurement was done from 12:00 to 15:00 on a sunny day in March. UV intensity was measured under the following conditions: 1) with or without eyeglasses, 2) wearing sunglasses with side protectors, and 3) wearing a cap with a 7 cm brim. Eyeglasses of four frame sizes (width: 48-57 mm) were put on the mannequin. All lenses were made of plastic and coated so as to be impervious to rays shorter than 400 nm. The refractive power was 0 diopters. At the same time, UV irradiation intensity from all directions (excluding from the earth direction) was measured using a polyhedron type UV sensor with 25 sensor chips. Except for eyeglasses with the smallest frame size, eyeglasses effectively reduced UV exposure to sunlight from the upper front direction. However, protection against rays from the upper temporal direction was extremely poor. Sunlight from the upper back was reflected by the posterior surface of the eyeglasses and reached the eye surface. The efficacy of eyeglasses against UV depends on their size. The shape of the eyeglasses and reflection from the posterior lens surface are also of great importance. Small eyeglasses do not offer ideal UV protection for the Japanese face shape.

Effect of ultraviolet light irradiation on bond strength of fiber post: Evaluation of surface characteristic and bonded area of fiber post with resin cement.

PubMed

Reza, Fazal; Ibrahim, Nur Sukainah

2015-01-01

Fiber post is cemented to a root canal to restore coronal tooth structure. This research aims to evaluate the effect of ultraviolet (UV) irradiation on bond strength of fiber post with resin cement. A total of 40 of the two types of fiber posts, namely, FRC Prostec (FRC) and Fiber KOR (KOR), were used for the experiment. UV irradiation was applied on top of the fiber post surface for 0, 15, 20, and 30 min. The irradiated surface of the fiber posts (n = 5) were immediately bonded with resin cement (Rely X U200) after UV irradiation. Shear bond strength (SBS) MPa was measured, and the dislodged area of post surfaces was examined with scanning electron microscopes. Changes in surface roughness (Ra) of the FRC group after UV irradiation were observed (n = 3) using atomic force microscopy. Data of SBS were statistically analyzed using one-way analysis of variance, followed by multiple comparisons (P < 0.05). SBS was significantly higher for 20 min of UV irradiation of the FRC group while significantly higher SBS was observed with 15 min of UV irradiation of the KOR group. Resin cement was more evident (cohesive failure) on the dislodged post surface of the UV treated groups compared with the control. The surface roughness of the FRC post was Ra = 175.1 nm and Ra = 929.2 nm for the control and the 20 min group, respectively. Higher surface roughness of the UV irradiated group indicated formation of mechanical retention on the fiber post surface. Evidence of cohesive failure was observed which indicated higher SBS of fiber post with the UV irradiated group.

Effect of ultraviolet light irradiation on bond strength of fiber post: Evaluation of surface characteristic and bonded area of fiber post with resin cement

PubMed Central

Reza, Fazal; Ibrahim, Nur Sukainah

2015-01-01

Objective: Fiber post is cemented to a root canal to restore coronal tooth structure. This research aims to evaluate the effect of ultraviolet (UV) irradiation on bond strength of fiber post with resin cement. Materials and Methods: A total of 40 of the two types of fiber posts, namely, FRC Prostec (FRC) and Fiber KOR (KOR), were used for the experiment. UV irradiation was applied on top of the fiber post surface for 0, 15, 20, and 30 min. The irradiated surface of the fiber posts (n = 5) were immediately bonded with resin cement (Rely X U200) after UV irradiation. Shear bond strength (SBS) MPa was measured, and the dislodged area of post surfaces was examined with scanning electron microscopes. Changes in surface roughness (Ra) of the FRC group after UV irradiation were observed (n = 3) using atomic force microscopy. Data of SBS were statistically analyzed using one-way analysis of variance, followed by multiple comparisons (P < 0.05). Results: SBS was significantly higher for 20 min of UV irradiation of the FRC group while significantly higher SBS was observed with 15 min of UV irradiation of the KOR group. Resin cement was more evident (cohesive failure) on the dislodged post surface of the UV treated groups compared with the control. The surface roughness of the FRC post was Ra = 175.1 nm and Ra = 929.2 nm for the control and the 20 min group, respectively. Conclusions: Higher surface roughness of the UV irradiated group indicated formation of mechanical retention on the fiber post surface. Evidence of cohesive failure was observed which indicated higher SBS of fiber post with the UV irradiated group. PMID:25713488

Far Ultraviolet Spectroscopy of Saturn's Icy Moon Rhea

NASA Astrophysics Data System (ADS)

Elowitz, Mark; Hendrix, Amanda; Mason, Nigel J.; Sivaraman, Bhalamurugan

2018-01-01

We present an analysis of spatially resolved, far-UV reflectance spectra of Saturn’s icy satellite Rhea, collected by the Cassini Ultraviolet Imaging Spectrograph (UVIS). In recent years ultraviolet spectroscopy has become an important tool for analysing the icy satellites of the outer solar system (1Hendrix & Hansen, 2008). Far-UV spectroscopy provides unique information about the molecular structure and electronic transitions of chemical species. Many molecules that are suspected to be present in the icy surfaces of moons in the outer solar system have broad absorption features due to electronic transitions that occur in the far-UV portion of the spectrum. The studies show that Rhea, like the other icy satellites of the Saturnian system are dominated by water-ice as evident by the 165-nm absorption edge, with minor UV absorbing contaminants. Far-UV spectra of several Saturnian icy satellites, including Rhea and Dione, show an unexplained weak absorption feature centered near 184 nm. To carry out the geochemical survey of Rhea’s surface, the UVIS observations are compared with vacuum-UV spectra of thin-ice samples measured in laboratory experiments. Thin film laboratory spectra of water-ice and other molecular compounds in the solid phase were collected at near-vacuum conditions and temperatures identical to those at the surface of Rhea. Comparison between the observed far-UV spectra of Rhea’s surface ice and modelled spectra based on laboratory absorption measurements of different non-water-ice compounds show that two possible chemical compounds could explain the 184-nm absorption feature. The two molecular compounds include simple chlorine molecules and hydrazine monohydrate. Attempts to explain the source(s) of these compounds on Rhea and the scientific implications of their possible discovery will be summarized.[1] Hendrix, A. R. & Hansen, C. J. (2008). Icarus, 193, pp. 323-333.

An Ultraviolet Spectrograph Concept for Exploring Ocean Worlds

NASA Astrophysics Data System (ADS)

Schindhelm, E. R.; Hendrix, A. R.; Fleming, B. T.

2018-05-01

UV spectroscopy can probe dust/ice composition of the surface or plumes via uniquely identifying features. We present a technology concept for a future planetary science UV multi-object imaging spectrograph.

Investigation of Ultraviolet Light Curable Polysilsesquioxane Gate Dielectric Layers for Pentacene Thin Film Transistors.

PubMed

Shibao, Hideto; Nakahara, Yoshio; Uno, Kazuyuki; Tanaka, Ichiro

2016-04-01

Polysilsesquioxane (PSQ) comprising 3-methacryloxypropyl groups was investigated as an ultraviolet (UV)-light curable gate dielectric-material for pentacene thin film transistors (TFTs). The surface of UV-light cured PSQ films was smoother than that of thermally cured ones, and the pentacene layers deposited on the UV-Iight cured PSQ films consisted of larger grains. However, carrier mobility of the TFTs using the UV-light cured PSQ films was lower than that of the TFTs using the thermally cured ones. It was shown that the cross-linker molecules, which were only added to the UV-light cured PSQ films, worked as a major mobility-limiting factor for the TFTs.

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

PubMed

Gorton, Holly L; Vogelmann, Thomas C

2003-06-01

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

Reduction of short wavelength reflectance of multi-wall carbon nanotubes through ultraviolet laser irradiation

NASA Astrophysics Data System (ADS)

Stephens, Michelle S.; Simonds, Brian J.; Yung, Christopher S.; Conklin, Davis; Livigni, David J.; Oliva, Alberto Remesal; Lehman, John H.

2018-05-01

Multi-wall carbon nanotube coatings are used as broadband, low-reflectance absorbers for bolometric applications and for stray light control. They are also used as high emittance blackbody radiators. Irradiation of single wall carbon nanotubes with ultraviolet (UV) laser light has been shown to remove amorphous carbon debris, but there have been few investigations of the interaction of UV light with the more complex physics of multi-wall carbon nanotubes. We present measurements of reflectance and surface morphology before and after exposure of multi-wall carbon nanotube coatings to 248 nm UV laser light. We show that UV exposure reduces the reflectivity at wavelengths below 600 nm and present modeling of the thermal cycling the UV exposure causes at the surface of the carbon nanotubes. This effect can be used to flatten the spectral shape of the reflectivity curve of carbon nanotube absorber coatings used for broadband applications. Finally, we find that the effect of UV exposure depends on the nanotube growth process.

An ESR study of the UV degradation of FEP

NASA Technical Reports Server (NTRS)

George, G. A.; Hill, D. J. T.; Odonnell, J. H.; Pomery, P. J.; Rasoul, F.

1992-01-01

Spacecraft in low earth orbit are subjected to significant levels of high energy radiation, including ultraviolet (UV) and visible ultraviolet (VUV) wavelengths. The effects of UV radiation are enhanced over those at the surface of the earth, where the only incident wavelengths are greater than 290 nm. In low earth orbit the incident UV wavelengths extend below 290 nm into the VUV region, where the Lyman alpha-emissions of atomic hydrogen occur at 121 nm. In addition to electromagnetic radiation, in low earth orbit polymer materials may also be subjected to atomic oxygen particle radiation, which will result in direct oxidation of the polymer.

Nanotherapy of cancer by photoelectrons emitted from the surface of nanoparticles exposed to nonionizing ultraviolet radiation.

PubMed

Letfullin, Renat R; George, Thomas F

2017-05-01

We introduce a new method for selectively destroying cancer cell organelles by electrons emitted from the surface of intracellularly localized nanoparticles exposed to the nonionizing ultraviolet (UV) radiation. We propose to target cancerous intracellular organelles by nanoparticles and expose them to UV radiation with energy density safe for healthy tissue. We simulate the number of photoelectrons produced by the nanoparticles made of various metals and radii, calculate their kinetic energy and compare it to the threshold energy for producing biological damage. Exposure of metal nanoparticles to UV radiation generates photoelectrons with kinetic energies up to 11 eV, which is high enough to produce single- to double-strand breaks in the DNA and damage the cancerous cell organelles.

INTERACTIONS OF SOLAR UV RADIATION AND DISSOLVED ORGANIC MATTER IN AQUATIC ENVIRONMENTS

EPA Science Inventory

Changes in the ozone layer over the past two decades have resulted in increases in solar ultraviolet (UV) radiation that reaches the surface of aquatic environments. Recent studies have demonstrated that these UV increases cause changes in photochemical reactions that affect the...

Ultraviolet radiation exposure from UV-transilluminators.

PubMed

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 < or =25 cm from the UV-transilluminator's filter surface. Daily exposure 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.

Photochemical tuning of ultrathin TiO2/ p-Si p-n junction properties via UV-induced H doping

NASA Astrophysics Data System (ADS)

Lee, Sang Yeon; Kim, Jinseo; Ahn, Byungmin; Cho, In Sun; Yu, Hak Ki; Seo, Hyungtak

2017-03-01

We report a modified TiO2/ p-Si electronic structure that uses ultraviolet exposure for the incorporation of H. This structure was characterized using various photoelectron spectroscopic techniques. The ultraviolet (UV) exposure of the TiO2 surface allowed the Fermi energy level to be tuned by the insertion of H radicals, which induced changes in the heterojunction TiO2/ p-Si diode properties. The UV exposure of the TiO2 surface was performed in air. On UVexposure, a photochemical reaction involving the incorporation of UV-induced H radicals led to the creation of a surface Ti-O-OH group and caused interstitial H doping (Ti-H-O) in the bulk, which modified the electronic structures in different ways, depending on the location of the H. On the basis of the band alignment determined using a combined spectroscopic analysis, it is suggested that the UV-induced H incorporation into the TiO2 could be utilized for the systematic tuning of the heterojunction property for solar cells, photocatalytic applications, and capacitors.

TECHNIQUES FOR DETERMINING UV EXPOSURE IN COASTAL WATERS: CASE STUDY IN SOUTH FLORIDA

EPA Science Inventory

The photosynthesis of coral reefs is inhibited by solar ultraviolet (UV) radiation and UV in combination with unusually high sea surface temperatures is believed to play an important role in coral bleaching. In this presentation we use a new technique based on remotely sensed oce...

Bidirectional Reflectance Function Measurement of Molecular Contaminant Scattering in the Vacuum Ultraviolet

NASA Technical Reports Server (NTRS)

Herren, Kenneth A.; Gregory, Don A.

2006-01-01

Bi-directional reflectance distribution function (BRDF) measurements of optical surfaces both before and after molecular contamination were done using UV, VUV and visible light. Molecular contamination of optical surfaces from outgassed material has been shown in many cases to proceed from acclimation centers, and to produce many roughly hemispherical "islands" of contamination on the surface. Vacuum Ultraviolet (VW) wavelengths are used here to measure angularly scattered light from optical surfaces.

Band-Bending of Ga-Polar GaN Interfaced with Al2O3 through Ultraviolet/Ozone Treatment.

PubMed

Kim, Kwangeun; Ryu, Jae Ha; Kim, Jisoo; Cho, Sang June; Liu, Dong; Park, Jeongpil; Lee, In-Kyu; Moody, Baxter; Zhou, Weidong; Albrecht, John; Ma, Zhenqiang

2017-05-24

Understanding the band bending at the interface of GaN/dielectric under different surface treatment conditions is critically important for device design, device performance, and device reliability. The effects of ultraviolet/ozone (UV/O 3 ) treatment of the GaN surface on the energy band bending of atomic-layer-deposition (ALD) Al 2 O 3 coated Ga-polar GaN were studied. The UV/O 3 treatment and post-ALD anneal can be used to effectively vary the band bending, the valence band offset, conduction band offset, and the interface dipole at the Al 2 O 3 /GaN interfaces. The UV/O 3 treatment increases the surface energy of the Ga-polar GaN, improves the uniformity of Al 2 O 3 deposition, and changes the amount of trapped charges in the ALD layer. The positively charged surface states formed by the UV/O 3 treatment-induced surface factors externally screen the effect of polarization charges in the GaN, in effect, determining the eventual energy band bending at the Al 2 O 3 /GaN interfaces. An optimal UV/O 3 treatment condition also exists for realizing the "best" interface conditions. The study of UV/O 3 treatment effect on the band alignments at the dielectric/III-nitride interfaces will be valuable for applications of transistors, light-emitting diodes, and photovoltaics.

Antarctic Ultraviolet Radiation Climatology from Total Ozone Mapping Spectrometer Data

NASA Technical Reports Server (NTRS)

Lubin, Dan

2004-01-01

This project has successfully produced a climatology of local noon spectral surface irradiance covering the Antarctic continent and the Southern Ocean, the spectral interval 290-700 nm (UV-A, UV-B, and photosynthetically active radiation, PAR), and the entire sunlit part of the year for November 1979-December 1999. Total Ozone Mapping Spectrometer (TOMS) data were used to specify column ozone abundance and UV-A (360- or 380-nm) reflectivity, and passive microwave (MW) sea ice concentrations were used to specify the surface albedo over the Southern Ocean. For this latter task, sea ice concentration retrievals from the Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) and its successor, the Defense Meteorological Satellite Program (DMSP) Special Sensor Microwave Imager (SSM/I) were identified with ultraviolet/visible-wavelength albedos based on an empirical TOMS/MW parameterization developed for this purpose (Lubin and Morrow, 2001). The satellite retrievals of surface albedo and UV-A reflectivity were used in a delta-Eddington radiative transfer model to estimate cloud effective optical depth. These optical depth estimates were then used along with the total ozone and surface albedo to calculate the downwelling spectral UV and PAR irradiance at the surface. These spectral irradiance maps were produced for every usable day of TOMS data between 1979-1999 (every other day early in the TOMS program, daily later on).

Effect of ultraviolet light irradiation and sandblasting treatment on bond strengths between polyamide and chemical-cured resin.

PubMed

Asakawa, Yuya; Takahashi, Hidekazu; Iwasaki, Naohiko; Kobayashi, Masahiro

2014-01-01

The aim of this study was to evaluate the effects of ultraviolet light (UV) irradiation and sandblasting treatment on the shear bond strength between polyamide and chemical-cured resin. Three types of commercial polyamides were treated using UV irradiation, sandblasting treatment, and a combining sandblasting and UV irradiation. The shear bond strength was measured and analyzed using the Kruskal-Wallis test (α=0.05). Comparing shear bond strengths without surface treatment, from 4.1 to 5.7 MPa, the UV irradiation significantly increased the shear bond strengths except for Valplast, whose shear bond strengths ranged from 5.2 to 9.3 MPa. The sandblasting treatment also significantly increased the shear bond strengths (8.0 to 11.4 MPa). The combining sandblasting and UV irradiation significantly increased the shear bond strengths (15.2 to 18.3 MPa) comparing without surface treatment. This combined treatment was considered the most effective at improving the shear bond strength between polyamide and chemical-cured resin.

Synthetic ultraviolet light filtering chemical contamination of coastal waters of Virgin Islands National Park, St. John, U.S. Virgin Islands

USGS Publications Warehouse

Bargar, Timothy A.; Alvarez, David; Garrison, Virginia H.

2015-01-01

Contamination of surface waters by synthetic ultraviolet light (UV) filtering chemicals is a concern for the Virgin Islands National Park (VINP). Discrete water samples were collected from VINP bays to determine UV filter chemical presence in the coastal waters. Spatial distribution and the potential for partitioning between subsurface waters and the sea surface microlayer (SML) were also examined. The UV filter chemicals 4-methylbenzylidene camphor, benzophenone-3, octinoxate, homosalate, and octocrylene were detected at concentrations up to 6073 ng/L (benzophenone-3). Concentrations for benzophenone-3 and homosalate declined exponentially (r2 = 0.86 to 0.98) with distance from the beach. Limited data indicate that some UV filter chemicals may partition to the SML relative to the subsurface waters. Contamination of VINP coastal waters by UV filter chemicals may be a significant issue, but an improved understanding of the temporal and spatial variability of their concentrations would be necessary to better understand the risk they present.

Atomic force imaging microscopy investigation of the interaction of ultraviolet radiation with collagen thin films

NASA Astrophysics Data System (ADS)

Stylianou, A.; Yova, D.; Alexandratou, E.; Petri, A.

2013-02-01

Collagen is the major fibrous protein in the extracellular matrix and consists a significant component of skin, bone, cartilage and tendon. Due to its unique properties, it has been widely used as scaffold or culture substrate for tissue regeneration or/and cell-substrate interaction studies. The ultraviolet light-collagen interaction investigations are crucial for the improvement of many applications such as that of the UV irradiation in the field of biomaterials, as sterilizing and photo-cross-linking method. The aim of this paper was to investigate the mechanisms of UV-collagen interactions by developing a collagen-based, well characterized, surface with controlled topography of collagen thin films in the nanoscale range. The methodology was to quantify the collagen surface modification induced on ultraviolet radiation and correlate it with changes induced in cells. Surface nanoscale characterization was performed by Atomic Force Microscopy (AFM) which is a powerful tool and offers quantitative and qualitative information with a non-destructive manner. In order to investigate cells behavior, the irradiated films were used for in vitro cultivation of human skin fibroblasts and the cells morphology, migration and alignment were assessed with fluorescence microscopy imaging and image processing methods. The clarification of the effects of UV light on collagen thin films and the way of cells behavior to the different modifications that UV induced to the collagen-based surfaces will contribute to the better understanding of cell-matrix interactions in the nanoscale and will assist the appropriate use of UV light for developing biomaterials.

'No touch' technologies for environmental decontamination: focus on ultraviolet devices and hydrogen peroxide systems.

PubMed

Weber, David J; Kanamori, Hajime; Rutala, William A

2016-08-01

This article reviews 'no touch' methods for disinfection of the contaminated surface environment of hospitalized patients' rooms. The focus is on studies that assessed the effectiveness of ultraviolet (UV) light devices, hydrogen peroxide systems, and self-disinfecting surfaces to reduce healthcare-associated infections (HAIs). The contaminated surface environment in hospitals plays an important role in the transmission of several key nosocomial pathogens including methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus spp., Clostridium difficile, Acinetobacter spp., and norovirus. Multiple clinical trials have now demonstrated the effectiveness of UV light devices and hydrogen peroxide systems to reduce HAIs. A limited number of studies have suggested that 'self-disinfecting' surfaces may also decrease HAIs. Many studies have demonstrated that terminal cleaning and disinfection with germicides is often inadequate and leaves environmental surfaces contaminated with important nosocomial pathogens. 'No touch' methods of room decontamination (i.e., UV devices and hydrogen peroxide systems) have been demonstrated to reduce key nosocomial pathogens on inoculated test surfaces and on environmental surfaces in actual patient rooms. Further UV devices and hydrogen peroxide systems have been demonstrated to reduce HAI. A validated 'no touch' device or system should be used for terminal room disinfection following discharge of patients on contact precautions. The use of a 'self-disinfecting' surface to reduce HAI has not been convincingly demonstrated.

Seasonal and diurnal variations in Martian surface ultraviolet irradiation: biological and chemical implications for the Martian regolith

NASA Astrophysics Data System (ADS)

Patel, M. R.; Bérces, A.; Kolb, C.; Lammer, H.; Rettberg, P.; Zarnecki, J. C.; Selsis, F.

2003-01-01

The issue of the variation of the surface ultraviolet (UV) environment on Mars was investigated with particular emphasis being placed on the interpretation of data in a biological context. A UV model has been developed to yield the surface UV irradiance at any time and place over the Martian year. Seasonal and diurnal variations were calculated and dose rates evaluated. Biological interpretation of UV doses is performed through the calculation of DNA damage effects upon phage T7 and Uracil, used as examples for biological dosimeters. A solar UV "hotspot" was revealed towards perihelion in the southern hemisphere, with a significant damaging effect upon these species. Diurnal profiles of UV irradiance are also seen to vary markedly between aphelion and perihelion. The effect of UV dose is also discussed in terms of the chemical environment of the Martian regolith, since UV irradiance can reach high enough levels so as to have a significant effect upon the soil chemistry. We show, by assuming that H2O is the main source of hydrogen in the Martian atmosphere, that the stoichiometrically desirable ratio of 2:1 for atmospheric H and O loss rates to space are not maintained and at present the ratio is about 20:1. A large planetary oxygen surface sink is therefore necessary, in contrast with escape to space. This surface oxygen sink has important implications for the oxidation potential and the toxicology of the Martian soil. UV-induced adsorption of O_{2}^{-} super-radicals plays an important role in the oxidative environment of the Martian surface, and the biologically damaging areas found in this study are also shown to be regions of high subsurface oxidation. Furthermore, we briefly cover the astrobiological implications for landing sites that are planned for future Mars missions

Indium nanoparticles for ultraviolet surface-enhanced Raman spectroscopy

NASA Astrophysics Data System (ADS)

Das, Rupali; Soni, R. K.

2018-05-01

Ultraviolet Surface-enhanced Raman spectroscopy (UVSERS) has emerged as an efficient molecular spectroscopy technique for ultra-sensitive and ultra-low detection of analyte concentration. The generic SERS substrates based on gold and silver nanostructures have been extensively explored for high local electric field enhancement only in visible-NIR region of the electromagnetic spectrum. The template synthesis of controlled nanoscale size metallic nanostructures supporting localized surface plasmon resonance (LSPR) in the UV region have been recently explored due to their ease of synthesis and potential applications in optoelectronic, catalysis and magnetism. Indium (In0) nanoparticles exhibit active surface plasmon resonance (SPR) in ultraviolet (UV) and deep-ultaviolet (DUV) region with optimal absorption losses. This extended accessibility makes indium a promising material for UV plasmonic, chemical sensing and more recently in UV-SERS. In this work, spherical indium nanoparticles (In NPs) were synthesized by modified polyol reduction method using NaBH4 having local surface plasmon resonance near 280 nm. The as-synthesized spherical In0 nanoparticles were then coated with thin silica shells of thickness ˜ 5nm by a modified Stober method protecting the nanoparticles from agglomeration, direct contact with the probed molecules as well as prevent oxidation of the nanoparticles. Morphological evolution of In0 nanoparticles and SiO2 coating were characterized by transmission electron microscope (TEM). An enhanced near resonant shell-isolated SERS activity from thin film of tryptophan (Tryp) molecules deposited on indium coated substrates under 325nm UV excitation was observed. Finite difference time domain (FDTD) method is employed to comprehend the experimental results and simulate the electric field contours which showed amplified electromagnetic field localized around the nanostructures. The comprehensive analysis indicates that indium is a promising alternate exogenous contrast agent for efficient Raman spectroscopy from molecules.

Ultraviolet disinfection of potable water

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

Wolfe, R.L.

Because of upcoming surface and groundwater regulations regarding the control of microbiological and chemical contaminants, there is a need to evaluate the feasibility and effectiveness of ultraviolet (UV) radiation for primary disinfection of potable water supplies. Data is presented on microbicidal wavelengths of UV and distribution of energy output for low and medium-pressure arc lamps. Both systems were found to perform equally well for inactivating microorganisms, but each had distinct advantages in different applications. Approximate dosages for 90% inactivation of selected microorganisms by UV is presented in a table. Cost analysis for disinfection is presented in two tables as wellmore » as the advantages and disadvantages of UV disinfection. 38 refs.« less

Surface passivation process of compound semiconductor material using UV photosulfidation

DOEpatents

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.

Surface activation of graphene oxide nanosheets by ultraviolet irradiation for highly efficient anti-bacterials

NASA Astrophysics Data System (ADS)

Veerapandian, Murugan; Zhang, Linghe; Krishnamoorthy, Karthikeyan; Yun, Kyusik

2013-10-01

A comprehensive investigation of anti-bacterial properties of graphene oxide (GO) and ultraviolet (UV) irradiated GO nanosheets was carried out. Microscopic characterization revealed that the GO nanosheet-like structures had wavy features and wrinkles or thin grooves. Fundamental surface chemical states of GO nanosheets (before and after UV irradiation) were investigated using x-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy. Minimum inhibitory concentration (MIC) results revealed that UV irradiated GO nanosheets have more pronounced anti-bacterial behavior than GO nanosheets and standard antibiotic, kanamycin. The MIC of UV irradiated GO nanosheets was 0.125 μg ml-1 for Escherichia coli and Salmonella typhimurium, 0.25 μg ml-1 for Bacillus subtilis and 0.5 μg ml-1 for Enterococcus faecalis, ensuring its potential as an anti-infective agent for controlling the growth of pathogenic bacteria. The minimum bactericidal concentration of normal GO nanosheets was determined to be two-fold higher than its corresponding MIC value, indicating promising bactericidal activity. The mechanism of anti-bacterial action was evaluated by measuring the enzymatic activity of β-d-galactosidase for the hydrolysis of o-nitrophenol-β-d-galactopyranoside.

ZnO nanorod arrays and direct wire bonding on GaN surfaces for rapid fabrication of antireflective, high-temperature ultraviolet sensors

NASA Astrophysics Data System (ADS)

So, Hongyun; Senesky, Debbie G.

2016-11-01

Rapid, cost-effective, and simple fabrication/packaging of microscale gallium nitride (GaN) ultraviolet (UV) sensors are demonstrated using zinc oxide nanorod arrays (ZnO NRAs) as an antireflective layer and direct bonding of aluminum wires to the GaN surface. The presence of the ZnO NRAs on the GaN surface significantly reduced the reflectance to less than 1% in the UV and 4% in the visible light region. As a result, the devices fabricated with ZnO NRAs and mechanically stable aluminum bonding wires (pull strength of 3-5 gf) showed higher sensitivity (136.3% at room temperature and 148.2% increase at 250 °C) when compared with devices with bare (uncoated) GaN surfaces. In addition, the devices demonstrated reliable operation at high temperatures up to 300 °C, supporting the feasibility of simple and cost-effective UV sensors operating with higher sensitivity in high-temperature conditions, such as in combustion, downhole, and space exploration applications.

Surface energy changes produced by ultraviolet-ozone irradiation of poly(methylmethacrylate), polycarbone and polytetrafluoroethylene

NASA Technical Reports Server (NTRS)

Ponter, A. B.; Jones, W. R., Jr.; Jansen, R. H.

1994-01-01

Contact angles of water and methylene iodide were measured as a function of UV/O3 treatment time for three polymers: poly(methylmethacrylate) (PMMA), polycarbonate, and polytetrafluoroethylene (PTFE). Surface roughnesses were also measured. Surface free energies were then calculated using relationships developed by Kaelble and Neumann. The surface energy of polycarbonate was found to increase (60 percent) during UV/O3 treatment. However, calculations on PMMA were hampered by the formation of a water soluble surface product. On PTFE surfaces, the UV/O3 treatment etched the surface causing large increases in surface roughness, rendering contact angle measurements impossible. It is concluded that care must be taken in interpreting contact angle measurements and surface energy calculations on UV/O3 treated polymer surfaces.

Surface processing: existing and potential applications of ultraviolet light.

PubMed

Manzocco, Lara; Nicoli, Maria Cristina

2015-01-01

Solid foods represent optimal matrices for ultraviolet processing with effects well beyond nonthermal surface disinfection. UV radiation favors hormetic response in plant tissues and degradation of toxic compound on the product surface. Photoinduced reactions can also provide unexplored possibilities to steer structure and functionality of food biopolymers. The possibility to extensively exploit this technology will depend on availability of robust information about efficacious processing conditions and adequate strategies to completely and homogeneously process food surface.

Ultraviolet radiation in the Atacama Desert.

PubMed

Cordero, R R; Damiani, A; Jorquera, J; Sepúlveda, E; Caballero, M; Fernandez, S; Feron, S; Llanillo, P J; Carrasco, J; Laroze, D; Labbe, F

2018-03-31

The world's highest levels of surface ultraviolet (UV) irradiance have been measured in the Atacama Desert. This area is characterized by its high altitude, prevalent cloudless conditions, and a relatively low total ozone column. In this paper, we provide estimates of the surface UV (monthly UV index at noon and annual doses of UV-B and UV-A) for all sky conditions in the Atacama Desert. We found that the UV index at noon during the austral summer is expected to be greater than 11 in the whole desert. The annual UV-B (UV-A) doses were found to range from about 3.5 kWh/m 2 (130 kWh/m 2 ) in coastal areas to 5 kWh/m 2 (160 kWh/m 2 ) on the Andean plateau. Our results confirm significant interhemispherical differences. Typical annual UV-B doses in the Atacama Desert are about 40% greater than typical annual UV-B doses in northern Africa. Mostly due to seasonal changes in the ozone, the differences between the Atacama Desert and northern Africa are expected to be about 60% in the case of peak UV-B levels (i.e. the UV-B irradiances at noon close to the summer solstice in each hemisphere). Interhemispherical differences in the UV-A are significantly lower since the effect of the ozone in this part of the spectrum is minor.

Influence of ultraviolet light irradiation on the corrosion behavior of carbon steel AISI 1015

NASA Astrophysics Data System (ADS)

Riazi, H. R.; Danaee, I.; Peykari, M.

2013-03-01

Corrosion of carbon steel in sodium chloride solution was studied under ultraviolet illumination using weight loss, polarization, electrochemical impedance spectroscopy and current transient tests. The polarization test revealed an increase in the corrosion current density observed under UV illumination. The impedance spectroscopy indicated that the charge transfer resistance of the system was decreased by irradiation of UV light on a carbon steel electrode. The weight loss of carbon steel in solution increased under UV light, which confirms the results obtained from electrochemical measurements. We propose that the main effect of UV irradiation is on the oxide film, which forms on the surface. Thus, in presence of UV, the conductivity of oxide film might increase and lead to higher metal dissolution and corrosion rate.

Further comparison of MODTRAN 5 to measured data in the UV band

NASA Astrophysics Data System (ADS)

Smith, Leon; Richardson, Mark; Ayling, Richard; Barlow, Nick

2014-10-01

The ability to accurately model background radiation from the sun is important in understanding the operation of missile systems with ultraviolet (UV) guard channels. In theory a missile system's UV channel detects a target's silhouette, caused by its `negative contrast' with respect to background UV radiation. The variation in background levels of UV will therefore have an effect on the operability of a missile system that utilises a UV channel. In this paper an update on the measurement and comparison of background UV-A radiation to data produced by Moderate Resolution Atmospheric Transmission 5 (MODTRAN®5) is given. In the past surface flux and radiance data calculated using MODTRAN®5 has been compared to data from the World Ozone and Ultraviolet Data Centre (WOUDC) archive, and measurements taken by the author at the Defence Academy of the UK. With the aid of spectral measurement equipment, new measurements have been made and compared with the radiance profiles produced by MODTRAN®5, including measurements made throughout both winter and summer months. Also discussed are the effects of scattering and absorption by different cloud types on the amount of radiation observed at the Earth's surface.

Inactivation of avirulent Yersinia pestis on food and food contact surfaces by ultraviolet light and freezing.

PubMed

Sommers, Christopher H; Sheen, Shiowshuh

2015-09-01

Yersinia pestis, the causative agent of plague, can occasionally be contracted as a naso-pharyngeal or gastrointestinal illness through consumption of contaminated meat. In this study, the use of 254 nm ultraviolet light (UV-C) to inactivate a multi-isolate cocktail of avirulent Y. pestis on food and food contact surfaces was investigated. When a commercial UV-C conveyor was used (5 mW/cm(2)/s) 0.5 J/cm(2) inactivated >7 log of the Y. pestis cocktail on agar plates. At 0.5 J/cm(2), UV-C inactivated ca. 4 log of Y. pestis in beef, chicken, and catfish, exudates inoculated onto high density polypropylene or polyethylene, and stainless steel coupons, and >6 log was eliminated at 1 J/cm(2). Approximately 1 log was inactivated on chicken breast, beef steak, and catfish fillet surfaces at a UV-C dose of 1 J/cm(2). UV-C treatment prior to freezing of the foods did not increase the inactivation of Y. pestis over freezing alone. These results indicate that routine use of UV-C during food processing would provide workers and consumers some protection against Y. pestis. Published by Elsevier Ltd.

ULTRAVIOLET RADIATION IN NORTH AMERICAN LAKES: ATTENUATION ESTIMATES FROM DOC MEASUREMENTS AND IMPLICATIONS FOR PLANKTON COMMUNITIES

EPA Science Inventory

Climate warming in North America is likely to be accompanied by changes in other environmental stresses such as UV-B radiation. We apply an empirical model to available DOC (dissolved organic C) data to estimate the depths to which 1% of surface UV-B and UV-A radiation penetrate ...

Is the pulsed xenon ultraviolet light no-touch disinfection system effective on methicillin-resistant Staphylococcus aureus in the absence of manual cleaning?

PubMed

Jinadatha, Chetan; Villamaria, Frank C; Restrepo, Marcos I; Ganachari-Mallappa, Nagaraja; Liao, I-Chia; Stock, Eileen M; Copeland, Laurel A; Zeber, John E

2015-08-01

Methicillin-resistant Staphylococcus aureus (MRSA) has been shown to survive on ambient surfaces for extended periods of time. Leftover MRSA environmental contamination in a hospital room places future patients at risk. Manual disinfection supplemented by pulsed xenon ultraviolet (PX-UV) light disinfection has been shown to greatly decrease the MRSA bioburden in hospital rooms. However, the effect of PX-UV in the absence of manual disinfection has not been evaluated. Rooms that were previously occupied by a MRSA-positive patient (current colonization or infection) were selected for the study immediately postdischarge. Five high-touch surfaces were sampled, before and after PX-UV disinfection, in each hospital room. The effectiveness of the PX-UV device on the concentration of MRSA was assessed employing a Wilcoxon signed-rank test for all 70 samples with MRSA in 14 rooms, as well as by surface location. The final analysis included 14 rooms. Before PX-UV disinfection there were a total of 393 MRSA colonies isolated from the 5 high-touch surfaces. There were 100 MRSA colonies after disinfection by the PX-UV device and the overall reduction was statistically significant (P < .01). Our study results suggest that PX-UV light effectively reduces MRSA colony counts in the absence of manual disinfection. These findings are important for hospital and environmental services supervisors who plan to adapt new technologies as an adjunct to routine manual disinfection. Published by Elsevier Inc.

Ultraviolet Imaging Telescope ultraviolet images - Large-scale structure, H II regions, and extinction in M81

NASA Technical Reports Server (NTRS)

Hill, Jesse K.; Bohlin, Ralph C.; Cheng, Kwang-Ping; Hintzen, Paul M. N.; Landsman, Wayne B.; Neff, Susan G.; O'Connell, Robert W.; Roberts, Morton S.; Smith, Andrew M.; Smith, Eric P.

1992-01-01

The study employs UV images of M81 obtained by the Ultraviolet Imaging Telescope (UIT) during the December 1990 Astro-1 spacelab mission to determine 2490- and 1520-A fluxes from 46 H II regions and global surface brightness profiles. Comparison photometry in the V band is obtained from a ground-based CCD image. UV radial profiles show bulge and exponential disk components, with a local decrease in disk surface brightness inside the inner Lindblad Resonance about 4 arcmin from the nucleus. The V profile shows typical bulge plus exponential disk structure, with no local maximum in the disk. There is little change of UV color across the disk, although there is a strong gradient in the bulge. Observed m152-V colors of the H II regions are consistent with model spectra for young clusters, after dereddening using Av determined from m249-V and the Galactic extinction curve. The value of Av, so determined, is 0.4 mag greater on the average than Av derived from radio continuum and H-alpha fluxes.

Aluminum nanostructures for ultraviolet plasmonics

NASA Astrophysics Data System (ADS)

Martin, Jérôme; Khlopin, Dmitry; Zhang, Feifei; Schuermans, Silvère; Proust, Julien; Maurer, Thomas; Gérard, Davy; Plain, Jérôme

2017-08-01

An electromagnetic field is able to produce a collective oscillation of free electrons at a metal surface. This allows light to be concentrated in volumes smaller than its wavelength. The resulting waves, called surface plasmons can be applied in various technological applications such as ultra-sensitive sensing, Surface Enhanced Raman Spectroscopy, or metal-enhanced fluorescence, to name a few. For several decades plasmonics has been almost exclusively studied in the visible region by using nanoparticles made of gold or silver as these noble metals support plasmonic resonances in the visible and near-infrared range. Nevertheless, emerging applications will require the extension of nano-plasmonics toward higher energies, in the ultraviolet range. Aluminum is one of the most appealing metal for pushing plasmonics up to ultraviolet energies. The subsequent applications in the field of nano-optics are various. This metal is therefore a highly promising material for commercial applications in the field of ultraviolet nano-optics. As a consequence, aluminum (or ultraviolet, UV) plasmonics has emerged quite recently. Aluminium plasmonics has been demonstrated efficient for numerous potential applications including non-linear optics, enhanced fluorescence, UV-Surface Enhanced Raman Spectroscopy, optoelectronics, plasmonic assisted solid-state lasing, photocatalysis, structural colors and data storage. In this article, different preparation methods developed in the laboratory to obtain aluminum nanostructures with different geometries are presented. Their optical and morphological characterizations of the nanostructures are given and some proof of principle applications such as fluorescence enhancement are discussed.

The Southwest Research Institute ultraviolet reflectance chamber (SwURC): a far ultraviolet reflectometer

NASA Astrophysics Data System (ADS)

Winters, Gregory S.; Retherford, Kurt D.; Davis, Michael W.; Escobedo, Stephen M.; Bassett, Eric C.; Patrick, Edward L.; Nagengast, Maggie E.; Fairbanks, Matthew H.; Miles, Paul F.; Parker, Joel W.; Gladstone, G. Randall; Slater, David C.; Stern, S. Alan

2012-10-01

We designed and assembled a highly capable UV reflectometer chamber and data acquisition system to provide bidirectional scattering data of various surfaces and materials. This chamber was initially conceived to create laboratory-based UV reflectance measurements of water frost on lunar soil/regolith simulants, to support interpretation of UV reflectance data from the Lyman Alpha Mapping Project ("LAMP") instrument on-board the NASA Lunar Reconnaissance Orbiter spacecraft. A deuterium lamp illuminates surfaces and materials at a fixed 45° incident beam angle over the 115 to 200 nm range via a monochromator, while a photomultiplier tube detector is scanned to cover emission angles -85° to +85° (with a gap from -60° to -30°, due to the detector blocking the incident beam). Liquid nitrogen cools the material/sample mount when desired. The chamber can be configured to test a wide range of samples and materials using sample trays and holders. Test surfaces to date include aluminum mirrors, water ice, reflectance standards, and frozen mixtures of water and lunar soil/regolith stimulant. Future UV measurements planned include Apollo lunar samples, meteorite samples, other ices, minerals, and optical surfaces. Since this chamber may well be able to provide useful research data for groups outside Southwest Research Institute, we plan to take requests from and collaborate with others in the UV and surface reflection research community.

Enhanced selective photocatalytic reduction of CO2 to CH4 over plasmonic Au modified g-C3N4 photocatalyst under UV-vis light irradiation

NASA Astrophysics Data System (ADS)

Li, Hailong; Gao, Yan; Xiong, Zhuo; Liao, Chen; Shih, Kaimin

2018-05-01

A series of Au-g-C3N4 (Au-CN) catalysts were prepared through a NaBH4-reduction method using g-C3N4 (CN) from pyrolysis of urea as precursor. The catalysts' surface area, crystal structure, surface morphology, chemical state, functional group composition and optical properties were characterized by X-ray diffraction, transmission electron microscope, X-ray photoelectron spectroscopy, ultraviolet visible (UV-vis) diffuse reflectance spectra, fourier transform infrared, photoluminescence and transient photocurrent analysis. The carbon dioxide (CO2) photoreduction activities under ultraviolet visible (UV-vis) light irradiation were significantly enhanced when gold (Au) was loaded on the surface of CN. 2Au-CN catalyst with Au to CN mole ratio of 2% showed the best catalytic activity. After 2 h UV-vis light irradiation, the methane (CH4) yield over the 2Au-CN catalyst was 9.1 times higher than that over the pure CN. The CH4 selectivity also greatly improved for the 2Au-CN compared to the CN. The deposited Au nanoparticles facilitated the separation of electron-hole pairs on the CN surface. Moreover, the surface plasmon resonance effect of Au further promoted the generation of hot electrons and visible light absorption. Therefore, Au loading significantly improved CO2 photoreduction performance of CN under UV-vis light irradiation.

Ultraviolet-C efficacy against a norovirus surrogate and hepatitis A virus on a stainless steel surface.

PubMed

Park, Shin Young; Kim, An-Na; Lee, Ki-Hoon; Ha, Sang-Do

2015-10-15

In this study, the effects of 10-300 mWs/cm(2) of ultraviolet radiation (UV-C) at 260 nm were investigated for the inactivation of two foodborne viruses: murine norovirus-1 (MNV-1; a human norovirus [NoV] surrogate) and hepatitis A virus (HAV). We used an experimentally contaminated stainless steel surface, a common food-contact surface, to examine the effects of low doses of UV-C radiation on MNV-1 and HAV titers. The modified Gompertz equation was used to generate non-linear survival curves and calculate dR-values as the UV-C dose of 90% reduction for MNV-1 (R(2)=0.95, RMSE=0.038) and HAV (R(2)=0.97, RMSE=0.016). Total MNV-1 and HAV titers significantly decreased (p<0.05) with higher doses of UV-C. MNV-1 and HAV were reduced to 0.0-4.4 and 0.0-2.6 log10PFU/ml, respectively, on the stainless steel surfaces by low-dose UV-C treatment. The dR-value, 33.3 mWs/cm(2) for MNV-1 was significantly (p<0.05) lower than 55.4 mWs/cm(2) of HAV. Therefore, the present study shows that HAV is more resistant to UV-C radiation than MNV-1. These data suggest that low doses of UV-C light on food contact surfaces could be effective to inactivate human NoV and HAV in restaurant, institutional, and industrial kitchens and facilities. Copyright © 2015 Elsevier B.V. All rights reserved.

Whales Use Distinct Strategies to Counteract Solar Ultraviolet Radiation

PubMed Central

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

2013-01-01

A current threat to the marine ecosystem is the high level of solar ultraviolet radiation (UV). Large whales have recently been shown to suffer sun-induced skin damage from continuous UV exposure. Genotoxic consequences of such exposure remain unknown for these long-lived marine species, as does their capacity to counteract UV-induced insults. We show that UV exposure induces mitochondrial DNA damage in the skin of seasonally sympatric fin, sperm, and blue whales and that this damage accumulates with age. However, counteractive molecular mechanisms are markedly different between species. For example, sperm whales, a species that remains for long periods at the sea surface, activate genotoxic stress pathways in response to UV exposure whereas the paler blue whale relies on increased pigmentation as the season progresses. Our study also shows that whales can modulate their responses to fluctuating levels of UV, and that different evolutionary constraints may have shaped their response strategies. PMID:23989080

Photochemical stability of UV-screening transparent acrylic copolymers of 2-(2-hydroxy-5-vinylphenyl)-2H-benzotriazole

NASA Technical Reports Server (NTRS)

Gupta, A.; Scott, G. W.; Kliger, D.; Vogl, O.

1983-01-01

The mechanism of photodegradation of certain hydroxyphenyl benzotriazole based ultraviolet absorbers has been investigated and a new polymerizable ultraviolet absorber in this group has been synthesized. The photoreactivity is entirely confined at the surface of polymethylmethacrylate films containing the ultraviolet absorbers as pendant groups. A mechanism involving sensitized photooxidation has been proposed to interpret the data.

Ultraviolet reflecting photonic microstructures in the King Penguin beak.

PubMed

Dresp, Birgitta; Jouventin, Pierre; Langley, Keith

2005-09-22

King and emperor penguins (Aptenodytes patagonicus and Aptenodytes forsteri) are the only species of marine birds so far known to reflect ultraviolet (UV) light from their beaks. Unlike humans, most birds perceive UV light and several species communicate using the near UV spectrum. Indeed, UV reflectance in addition to the colour of songbird feathers has been recognized as an important signal when choosing a mate. The king penguin is endowed with several highly coloured ornaments, notably its beak horn and breast and auricular plumage, but only its beak reflects UV, a property considered to influence its sexual attraction. Because no avian UV-reflecting pigments have yet been identified, the origin of such reflections is probably structural. In an attempt to identify the structures that give rise to UV reflectance, we combined reflectance spectrophotometry and morphological analysis by both light and electron microscopy, after experimental removal of surface layers of the beak horn. Here, we characterize for the first time a multilayer reflector photonic microstructure that produces the UV reflections in the king penguin beak.

UV Signatures of Ices: Moons in the Solar System

NASA Astrophysics Data System (ADS)

Hendrix, A. R.; Hansen, C. J.; Retherford, K. D.; Vilas, F.

2017-12-01

Using Earth-orbiting telescopes such as the International Ultraviolet Explorer and the Hubble Space Telescope, significant advances have been made in the area of ultraviolet observations of solar system objects. More in-depth studies have been made using interplanetary probes such as Galileo, Cassini and Lunar Reconnaissance Orbiter (LRO). While the UV spectral range has traditionally been used to study atmospheric and auroral processes, there is much to be learned by examining solid surfaces in the UV, including surface composition, weathering processes and effects, and the generation of thin atmospheres. Here we focus on moons in the solar system, including Earth's moon and the Saturnian satellites. The diagnostic UV signature of H2O is used to study ice in the lunar polar regions as well as hydration at lower latitudes, in observations from LRO LAMP. The water ice signature is nearly ubiquitous in the Saturn system; Cassini UVIS datasets are used to study grain sizes, exogenic processes/effects and non-ice species.

Time-dependent effects of ultraviolet and nonthermal atmospheric pressure plasma on the biological activity of titanium

NASA Astrophysics Data System (ADS)

Choi, Sung-Hwan; Jeong, Won-Seok; Cha, Jung-Yul; Lee, Jae-Hoon; Yu, Hyung-Seog; Choi, Eun-Ha; Kim, Kwang-Mahn; Hwang, Chung-Ju

2016-09-01

Here, we evaluated time-dependent changes in the effects of ultraviolet (UV) and nonthermal atmospheric pressure plasma (NTAPPJ) on the biological activity of titanium compared with that of untreated titanium. Grade IV machined surface titanium discs (12-mm diameter) were used immediately and stored up to 28 days after 15-min UV or 10-min NTAPPJ treatment. Changes of surface characteristics over time were evaluated using scanning electron microscopy, surface profiling, contact angle analysis, X-ray photoelectron spectroscopy, and surface zeta-potential. Changes in biological activity over time were as determined by analysing bovine serum albumin adsorption, MC3T3-E1 early adhesion and morphometry, and alkaline phosphatase (ALP) activity between groups. We found no differences in the effects of treatment on titanium between UV or NTAPPJ over time; both treatments resulted in changes from negatively charged hydrophobic (bioinert) to positively charged hydrophilic (bioactive) surfaces, allowing enhancement of albumin adsorption, osteoblastic cell attachment, and cytoskeleton development. Although this effect may not be prolonged for promotion of cell adhesion until 4 weeks, the effects were sufficient to maintain ALP activity after 7 days of incubation. This positive effect of UV and NTAPPJ treatment can enhance the biological activity of titanium over time.

Importance of biologically active aurora-like ultraviolet emission: stochastic irradiation of Earth and Mars by flares and explosions.

PubMed

Smith, David S; Scalo, John; Wheeler, J Craig

2004-10-01

Habitable planets will be subject to intense sources of ionizing radiation and fast particles from a variety of sources--from the host star to distant explosions--on a variety of timescales. Monte Carlo calculations of high-energy irradiation suggest that the surfaces of terrestrial-like planets with thick atmospheres (column densities greater than about 100 g cm(-2)) are well protected from directly incident X-rays and gamma-rays, but we find that sizeable fractions of incident ionizing radiation from astrophysical sources can be redistributed to biologically and chemically important ultraviolet wavelengths, a significant fraction of which can reach the surface. This redistribution is mediated by secondary electrons, resulting from Compton scattering and X-ray photoabsorption, the energies of which are low enough to excite and ionize atmospheric molecules and atoms, resulting in a rich aurora-like spectrum. We calculate the fraction of energy redistributed into biologically and chemically important wavelength regions for spectra characteristic of stellar flares and supernovae using a Monte-Carlo transport code and then estimate the fraction of this energy that is transmitted from the atmospheric altitudes of redistribution to the surface for a few illustrative cases. For atmospheric models corresponding to the Archean Earth, we assume no significant ultraviolet absorbers, only Rayleigh scattering, and find that the fraction of incident ionizing radiation that is received at the surface in the form of redistributed ultraviolet in the biologically relevant 200-320 nm region (UV-C and UV-B bands) can be up to 4%. On the present-day Earth with its ultraviolet ozone shield, this fraction is found to be 0.2%. Both values are many orders of magnitude higher than the fraction of direct ionizing radiation reaching the surface. This result implies that planetary organisms will be subject to mutationally significant, if intermittent, fluences of UV-B and harder radiation even in the presence of a narrow-band ultraviolet shield like ozone. We also calculate the surficial transmitted fraction of ionizing radiation and redistributed ultraviolet radiation for two illustrative evolving Mars atmospheres whose initial surface pressures were 1 bar. We discuss the frequency with which redistributed ultraviolet flux from parent star flares exceeds the parent star ultraviolet flux at the planetary surface. We find that the redistributed ultraviolet from parent star flares is probably a fairly rare intermittent event for habitable zone planets orbiting solar-type stars except when they are young, but should completely dominate the direct steady ultraviolet radiation from the parent star for planets orbiting all stars less massive than about 0.5 solar masses. Our results suggest that coding organisms on such planets (and on the early Earth) may evolve very differently than on contemporary Earth, with diversity and evolutionary rate controlled by a stochastically varying mutation rate and frequent hypermutation episodes.

Harmful and favourable ultraviolet conditions for human health over Northern Eurasia

NASA Astrophysics Data System (ADS)

Chubarova, Nataly; Zhdanova, Ekaterina

2014-05-01

We provide the analysis of the spatial and temporal distribution of ultraviolet (UV) radiation over Northern Eurasia taking into account for both its detrimental (erythema and eye-damage effects) and favourable (vitamin D synthesis) influence on human health. The UV effects on six different skin types are considered in order to cover the variety of skin types of European and Asian inhabitants. To better quantifying the vitamin D irradiance threshold we accounted for an open body fraction S as a function of effective air temperature. The spatial and temporal distribution of UV resources was estimated by radiative transfer (RT) modeling (8 stream DISORT RT code) with 1x 1 degree grid and monthly resolution. For this purpose special datasets of main input geophysical parameters (total ozone content, aerosol characteristics, surface UV albedo, UV cloud modification factor) have been created over the territory of Northern Eurasia, which can be of separate interest for the different multidisciplinary scientific applications over the PEEX domain. The new approaches were used to retrieve aerosol and cloud transmittance from different satellite and re-analysis datasets for calculating the solar UV irradiance at ground. Using model simulations and some experimental data we provide the altitude parameterization for different types of biologically active irradiance in mountainous area taking into account not only for the effects of molecular scattering but for the altitude dependence of aerosol parameters and surface albedo. Based on the new classification of UV resources (Chubarova, Zhdanova, 2013) we show that the distribution of harmful (UV deficiency and UV excess) and favorable UV conditions is regulated by various geophysical parameters (mainly, total ozone, cloudiness and open body fraction) and can significantly deviate from latitudinal dependence. The interactive tool for providing simulations of biologically active irradiance and its attribution to the different classes of UV resources is demonstrated. Reference: Natalia Chubarova, Yekaterina Zhdanova. Ultraviolet resources over Northern Eurasia, Photochemistry and Photobiology, Elsevier, 127, 2013, p. 38-51

Innovative Approach to Validation of Ultraviolet (UV) Reactors for Disinfection in Drinking Water Systems - presentation

EPA Science Inventory

UV disinfection is an effective process for inactivating many microbial pathogens found in source waters with the potential as stand-alone treatment or in combination with other disinfectants. For surface and groundwater sourced drinking water applications, the U.S. Environmental...

EXPERIMENTS - APOLLO 17

NASA Image and Video Library

1972-11-17

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

Ultraviolet emission enhancement in ZnO thin films modified by nanocrystalline TiO2

NASA Astrophysics Data System (ADS)

Zheng, Gaige; Lu, Xi; Qian, Liming; Xian, Fenglin

2017-05-01

In this study, nanocrystalline TiO2 modified ZnO thin films were prepared by electron beam evaporation. The structural, morphological and optical properties of the samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), UV-visible spectroscopy, fluorescence spectroscopy, respectively. The composition of the films was examined by energy dispersive X-ray spectroscopy (EDX). The photoluminescent spectrum shows that the pure ZnO thin film exhibits an ultraviolet (UV) emission peak and a strong green emission band. Surface analysis indicates that the ZnO thin film contains many oxygen vacancy defects on the surface. After the ZnO thin film is modified by the nanocrystalline TiO2 layer, the UV emission of ZnO is largely enhanced and the green emission is greatly suppressed, which suggests that the surface defects such as oxygen vacancies are passivated by the TiO2 capping layer. As for the UV emission enhancement of the ZnO thin film, the optimized thickness of the TiO2 capping layer is ∼16 nm. When the thickness is larger than 16 nm, the UV emission of the ZnO thin film will decrease because the TiO2 capping layer absorbs most of the excitation energy. The UV emission enhancement in the nanocrystalline TiO2 modified ZnO thin film can be attributed to surface passivation and flat band effect.

Mutagenesis of Trichoderma Viride by Ultraviolet and Plasma

NASA Astrophysics Data System (ADS)

Yao, Risheng; Li, Manman; Deng, Shengsong; Hu, Huajia; Wang, Huai; Li, Fenghe

2012-04-01

Considering the importance of a microbial strain capable of increased cellulase production, a mutant strain UP4 of Trichoderma viride was developed by ultraviolet (UV) and plasma mutation. The mutant produced a 21.0 IU/mL FPase which was 98.1% higher than that of the parent strain Trichoderma viride ZY-1. In addition, the effect of ultraviolet and plasma mutagenesis was not merely simple superimposition of single ultraviolet mutation and single plasma mutation. Meanwhile, there appeared a capsule around some of the spores after the ultraviolet and plasma treatment, namely, the spore surface of the strain became fuzzy after ultraviolet or ultraviolet and plasma mutagenesis.

Evaluation of an Innovative Approach to Validation of Ultraviolet (UV) Reactors for Disinfection in Drinking Water Systems

EPA Science Inventory

UV disinfection is an effective process for inactivating many microbial pathogens found in source waters with the potential as stand-alone treatment or in combination with other disinfectants. For surface and groundwater sourced drinking water applications, the U.S. Environmental...

INTERACTIONS OF LIGHT AND CHEMICAL REACTIONS IN THE AQUATIC ENVIRONMENT: KINETIC AND MECHANISTIC ASPECTS

EPA Science Inventory

Changes in the ozone layer over the past two decades have resulted in increases in solar ultraviolet (UV) radiation that reaches the surface of aquatic environments. Recent studies have demonstrated that these UV increases cause changes in photochemical reactions that affect the...

Ultraviolet radiation-induced interleukin 6 release in HeLa cells is mediated via membrane events in a DNA damage-independent way.

PubMed

Kulms, D; Pöppelmann, B; Schwarz, T

2000-05-19

Evidence exists that ultraviolet radiation (UV) affects molecular targets in the nucleus or at the cell membrane. UV-induced apoptosis was found to be mediated via DNA damage and activation of death receptors, suggesting that nuclear and membrane effects are not mutually exclusive. To determine whether participation of nuclear and membrane components is also essential for other UV responses, we studied the induction of interleukin-6 (IL-6) by UV. Exposing HeLa cells to UV at 4 degrees C, which inhibits activation of surface receptors, almost completely prevented IL-6 release. Enhanced repair of UV-mediated DNA damage by addition of the DNA repair enzyme photolyase did not affect UV-induced IL-6 production, suggesting that in this case membrane events predominant over nuclear effects. UV-induced IL-6 release is mediated via NFkappaB since the NFkappaB inhibitor MG132 or transfection of cells with a super-repressor form of the NFkappaB inhibitor IkappaB reduced IL-6 release. Transfection with a dominant negative mutant of the signaling protein TRAF-2 reduced IL-6 release upon exposure to UV, indicating that UV-induced IL-6 release is mediated by activation of the tumor necrosis factor receptor-1. These data demonstrate that UV can exert biological effects mainly by affecting cell surface receptors and that this is independent of its ability to induce nuclear DNA damage.

Galileo Ultraviolet Spectrometer experiment

NASA Technical Reports Server (NTRS)

Hord, C. W.; Mcclintock, W. E.; Stewart, A. I. F.; Barth, C. A.; Esposito, L. W.; Thomas, G. E.; Sandel, B. R.; Hunten, D. M.; Broadfoot, A. L.; Shemansky, D. E.

1992-01-01

The Galileo ultraviolet spectrometer experiment uses data obtained by the Ultraviolet Spectrometer (UVS) mounted on the pointed orbiter scan platform and from the Extreme Ultraviolet Spectrometer (EUVS) mounted on the spinning part of the orbiter with the field of view perpendicular to the spin axis. The UVS is a Ebert-Fastie design that covers the range 113-432 nm with a wavelength resolution of 0.7 nm below 190 and 1.3 nm at longer wavelengths. The UVS spatial resolution is 0.4 deg x 0.1 deg for illuminated disk observations and 1 deg x 0.1 deg for limb geometries. The EUVS is a Voyager design objective grating spectrometer, modified to cover the wavelength range from 54 to 128 nm with wavelength resolution 3.5 nm for extended sources and 1.5 nm for point sources and spatial resolution of 0.87 deg x 0.17 deg. The EUVS instrument will follow up on the many Voyager UVS discoveries, particularly the sulfur and oxygen ion emissions in the Io torus and molecular and atomic hydrogen auroral and airglow emissions from Jupiter. The UVS will obtain spectra of emission, absorption, and scattering features in the unexplored, by spacecraft, 170-432 nm wavelength region. The UVS and EUVS instruments will provide a powerful instrument complement to investigate volatile escape and surface composition of the Galilean satellites, the Io plasma torus, micro- and macro-properties of the Jupiter clouds, and the composition structure and evolution of the Jupiter upper atmosphere.

Development of Ultraviolet (UV) Radiation Protective Fabric Using Combined Electrospinning and Electrospraying Technique

NASA Astrophysics Data System (ADS)

Sinha, Mukesh Kumar; Das, B. R.; Kumar, Kamal; Kishore, Brij; Prasad, N. Eswara

2017-06-01

The article reports a novel technique for functionization of nanoweb to develop ultraviolet (UV) radiation protective fabric. UV radiation protection effect is produced by combination of electrospinning and electrospraying technique. A nanofibrous web of polyvinylidene difluoride (PVDF) coated on polypropylene nonwoven fabric is produced by latest nanospider technology. Subsequently, web is functionalized by titanium dioxide (TiO2). The developed web is characterized for evaluation of surface morphology and other functional properties; mechanical, chemical, crystalline and thermal. An optimal (judicious) nanofibre spinning condition is achieved and established. The produced web is uniformly coated by defect free functional nanofibres in a continuous form of useable textile structural membrane for ultraviolet (UV) protective clothing. This research initiative succeeds in preparation and optimization of various nanowebs for UV protection. Field Emission Scanning Electron Microscope (FESEM) result reveals that PVDF webs photo-degradative behavior is non-accelerated, as compared to normal polymeric grade fibres. Functionalization with TiO2 has enhanced the photo-stability of webs. The ultraviolet protection factor of functionalized and non-functionalized nanowebs empirically evaluated to be 65 and 24 respectively. The developed coated layer could be exploited for developing various defence, para-military and civilian UV protective light weight clothing (tent, covers and shelter segments, combat suit, snow bound camouflaging nets). This research therefore, is conducted in an attempt to develop a scientific understanding of PVDF fibre coated webs for photo-degradation and applications for defence protective textiles. This technological research in laboratory scale could be translated into bulk productionization.

Calibration of optimal use parameters for an ultraviolet light-emitting diode in eliminating bacterial contamination on needleless connectors.

PubMed

Hutchens, M P; Drennan, S L; Cambronne, E D

2015-06-01

Needleless connectors may develop bacterial contamination and cause central-line-associated bloodstream infections (CLABSI) despite rigorous application of best-practice. Ultraviolet (UV) light-emitting diodes (LED) are an emerging, increasingly affordable disinfection technology. We tested the hypothesis that a low-power UV LED could reliably eliminate bacteria on needleless central-line ports in a laboratory model of central-line contamination. Needleless central-line connectors were inoculated with Staphylococcus aureus. A 285 nm UV LED was used in calibrated fashion to expose contaminated connectors. Ports were directly applied to agar plates and flushed with sterile saline, allowing assessment of bacterial survival on the port surface and in simulated usage flow-through fluid. UV applied to needleless central-line connectors was highly lethal at 0·5 cm distance at all tested exposure times. At distances >1·5 cm both simulated flow-through and port surface cultures demonstrated significant bacterial growth following UV exposure. Logarithmic-phase S. aureus subcultures were highly susceptible to UV induction/maintenance dosing. Low-power UV LED doses at fixed time and distance from needleless central-line connector ports reduced cultivable S. aureus from >10(6) CFU to below detectable levels in this laboratory simulation of central-line port contamination. Low-power UV LEDs may represent a feasible alternative to current best-practice in connector decontamination. © 2015 The Society for Applied Microbiology.

Local surface plasmon enhanced polarization and internal quantum efficiency of deep ultraviolet emissions from AlGaN-based quantum wells.

PubMed

Zhang, Cai; Tang, Ning; Shang, Liangliang; Fu, Lei; Wang, Weiying; Xu, Fujun; Wang, Xinqiang; Ge, Weikun; Shen, Bo

2017-05-24

We report the enhancement of the polarization and internal quantum efficiency (IQE) of deep-UV LEDs by evaporating Al nanoparticles on the device surface to induce localized surface plasmons (LSPs). The deep-UV LEDs polarization is improved due to part of TM emission turns into TE emission through LSPs coupling. The significantly enhanced IQE is attributed to LSPs coupling, which suppress the participation of delocalized and dissociated excitons to non-radiative recombination process.

Control of an Estuarine Microfouling Sequence on Optical Surfaces Using Low-Intensity Ultraviolet Irradiation

PubMed Central

DiSalvo, L. H.; Cobet, A. B.

1974-01-01

Ultraviolet light has been investigated as an active energy input for the control of slime film formation on optical surfaces submerged in San Francisco Bay for periods up to 6 weeks. Irradiation of quartz underwater windows was carried out from three positions: (i) exterior to the window, (ii) from directly behind the window, and (iii) from the edge of the window with the ultraviolet (UV) energy refracted through the front of the window. Internally administered irradiation reaching levels of 10 to 30 μW per cm2 measurable at the glass surface was effective in preventing bacterial slime film formation and settlement of metazoan larvae. When administered from the external position, over one order of magnitude more (500 to 600 μW/cm2) UV energy was required to accomplish the same result. Irradiation from the edge position was most promising logistically and was effective in fouling control for 6 weeks. The results provide a preliminary quantitation of the energy requirement for control of the marine microfouling sequence which precedes development of macrofouling communities. Images PMID:16349978

In situ measurement of VUV/UV radiation from low-pressure microwave-produced plasma in Ar/O2 gas mixtures

NASA Astrophysics Data System (ADS)

Iglesias, E. J.; Mitschker, F.; Fiebrandt, M.; Bibinov, N.; Awakowicz, P.

2017-08-01

Ultraviolet (UV) and vacuum ultraviolet (VUV) spectral irradiance is determined in low-pressure microwave-produced plasma, which is regularly used for polymer surface treatment. The re-emitted fluorescence in the UV/VIS spectral range from a sodium salicylate layer is measured. This fluorescence is related to VUV/UV radiation in different spectral bands based on cut-off filters. The background produced by direct emitted radiation in the fluorescence spectral region is quantified using a specific background filter, thus enabling the use of the whole fluorescence spectral range. A novel procedure is applied to determine the absolute value of the VUV/UV irradiance on a substrate. For that, an independent measurement of the absolute spectral emissivity of the plasma in the UV is performed. The measured irradiances on a substrate from a 25 Pa Ar/O2-produced plasma are in the range of 1015-1016 (photon~ s-1 cm-2). These values include the contribution from impurities present in the discharge.

Surface/Interface Carrier-Transport Modulation for Constructing Photon-Alternative Ultraviolet Detectors Based on Self-Bending-Assembled ZnO Nanowires.

PubMed

Guo, Zhen; Zhou, Lianqun; Tang, Yuguo; Li, Lin; Zhang, Zhiqi; Yang, Hongbo; Ma, Hanbin; Nathan, Arokia; Zhao, Dongxu

2017-09-13

Surface/interface charge-carrier generation, diffusion, and recombination/transport modulation are especially important in the construction of photodetectors with high efficiency in the field of nanoscience. In the paper, a kind of ultraviolet (UV) detector is designed based on ZnO nanostructures considering photon-trapping, surface plasmonic resonance (SPR), piezophototronic effects, interface carrier-trapping/transport control, and collection. Through carefully optimized surface/interface carrier-transport modulation, a designed device with detectivity as high as 1.69 × 10 16 /1.71 × 10 16 cm·Hz 1/2 /W irradiating with 380 nm photons under ultralow bias of 0.2 V is realized by alternating nanoparticle/nanowire active layers, respectively, and the designed UV photodetectors show fast and slow recovery processes of 0.27 and 4.52 ms, respectively, which well-satisfy practical needs. Further, it is observed that UV photodetection could be performed within an alternative response by varying correlated key parameters, through efficient surface/interface carrier-transport modulation, spectrally resolved photoresponse of the detector revealing controlled detection in the UV region based on the ZnO nanomaterial, photodetection allowed or limited by varying the active layers, irradiation distance from one of the electrodes, standing states, or electric field. The detailed carrier generation, diffusion, and recombination/transport processes are well illustrated to explain charge-carrier dynamics contributing to the photoresponse behavior.

Measurements of Raman scattering in the middle ultraviolet band from persistent chemical warfare agents

NASA Astrophysics Data System (ADS)

Kullander, Fredrik; Landström, Lars; Lundén, Hampus; Mohammed, Abdesalam; Olofsson, Göran; Wästerby, Pär.

2014-05-01

The very low Raman scattering cross section and the fluorescence background limit the measuring range of Raman based instruments operating in the visible or infrared band. We are exploring if laser excitation in the middle ultraviolet (UV) band between 200 and 300 nm is useful and advantageous for detection of persistent chemical warfare agents (CWA) on various kinds of surfaces. The UV Raman scattering from tabun, mustard gas, VX and relevant simulants in the form of liquid surface contaminations has been measured using a laboratory experimental setup with a short standoff distance around 1 meter. Droplets having a volume of 1 μl were irradiated with a tunable pulsed laser swept within the middle UV band. A general trend is that the signal strength moves through an optimum when the laser excitation wavelength is swept between 240 and 300 nm. The signal from tabun reaches a maximum around 265 nm, the signal from mustard gas around 275 nm. The Raman signal from VX is comparably weak. Raman imaging by the use of a narrow bandpass UV filter is also demonstrated.

Ultraviolet Imaging with Low Cost Smartphone Sensors: Development and Application of a Raspberry Pi-Based UV Camera.

PubMed

Wilkes, Thomas C; McGonigle, Andrew J S; Pering, Tom D; Taggart, Angus J; White, Benjamin S; Bryant, Robert G; Willmott, Jon R

2016-10-06

Here, we report, for what we believe to be the first time, on the modification of a low cost sensor, designed for the smartphone camera market, to develop an ultraviolet (UV) camera system. This was achieved via adaptation of Raspberry Pi cameras, which are based on back-illuminated complementary metal-oxide semiconductor (CMOS) sensors, and we demonstrated the utility of these devices for applications at wavelengths as low as 310 nm, by remotely sensing power station smokestack emissions in this spectral region. Given the very low cost of these units, ≈ USD 25, they are suitable for widespread proliferation in a variety of UV imaging applications, e.g., in atmospheric science, volcanology, forensics and surface smoothness measurements.

Inactivation of avirulent Yersinia pestis on food and food contact surfaces by ultraviolet light and freezing

USDA-ARS?s Scientific Manuscript database

Yersinia pestis, the causative agent of plague, can occasionally be contracted as a naso-pharangeal or gastrointestinal illness through consumption of contaminated meat. In this study, the use of 254 nm ultraviolet light (UV-C) to inactivate a multi-isolate cocktail of avirulent Y. pestis on food an...

Ultraviolet Light Surface Treatment as an Environmentally Benign Process for Production, Maintenance and Repair of Military Composite Structures

NASA Astrophysics Data System (ADS)

Drzal, Lawrence T.

2002-02-01

The principal objective of this work is to develop a low-cost, high-speed, environmentally benign, dry surface treatment method for production, and repair of military composite structures using ultraviolet (UV) light in ambient air. The potential advantage of this method is that it would eliminate volatile organic wastes (VOCs), reduce or eliminate the use of solutions and detergents, and provide a robust surface that would enhance or eliminate the use of solutions and detergents, and provide a robust surface that would enhance the wetting and spreading of paints, coatings and adhesives on polymeric and inorganic surfaces treated by this method. A manufacturing base for UV production equipment is in place although not for this application. There is a need for development of an environmentally friendly, cost effective as well as a robust surface treatment method that can clean a surface as well as create a beneficial chemistry for painting and produce optimum adhesive bonding of polymers, polymer composites and metal surfaces. With this in mind, three main technical objectives were sought in the work. The first objective was to determine the usefulness of UV and UV/O(3) to surface treatments to clean and chemically modify the surface of typical PMCs used in DOD systems. The second objective was to determine the effectiveness of this surface preparation for production and/or repair of adhesively bonded, painted and/or coated polymer matrix composite structures. Finally, a determination of the environmental and performance benefits of this method as a new environmentally benign processing method for the production and/or re air of adhesively SERDP, SERDP collection, robust surface, polymeric surface, inorganic surface, volatile organic compounds (VOC) emissions.

An ultraviolet simulator for the incident Martian surface radiation and its applications

NASA Astrophysics Data System (ADS)

Kolb, C.; Abart, R.; Bérces, A.; Garry, J. R. C.; Hansen, A. A.; Hohenau, W.; Kargl, G.; Lammer, H.; Patel, M. R.; Rettberg, P.; Stan-Lotter, H.

2005-10-01

Ultraviolet (UV) radiation can act on putative organic/biological matter at the Martian surface in several ways. Only absorbed, but not transmitted or reflected, radiation energy can be photo-chemically effective. The most important biological UV effects are due to photochemical reactions in nucleic acids, DNA or RNA, which constitute the genetic material of all cellular organisms and viruses. Protein or lipid effects generally play a minor role, but they are also relevant in some cases. UV radiation can induce wavelengths-specific types of DNA damage. At the same time it can also induce the photo-reversion reaction of a UV induced DNA photoproduct of nucleic acid bases, the pyrimidine dimers. Intense UVB and UVC radiation, experienced on early Earth and present-day Mars, has been revealed to be harmful to all organisms, including extremophile bacteria and spores. Moreover, the formation of oxidants, catalytically produced in the Martian environment through UV irradiation, may be responsible for the destruction of organic matter on Mars. Following this, more laboratory simulations are vital in order to investigate and understand UV effects on organic matter in the case of Mars. We have designed a radiation apparatus that simulates the anticipated Martian UV surface spectrum between 200 and 400 nm (UVC UVA). The system comprises a UV enhanced xenon arc lamp, special filter-sets and mirrors to simulate the effects of the Martian atmospheric column and dust loading. We describe the technical setup and performance of the system and discuss its uses for different applications. The design is focused on portability, therefore, the Mars-UV simulator represents a device for several different Mars simulation facilities with specific emphasis on Mars research topics.

Effects of rutin on the physicochemical properties of skin fibroblasts membrane disruption following UV radiation.

PubMed

Dobrzyńska, Izabela; Gęgotek, Agnieszka; Gajko, Ewelina; Skrzydlewska, Elżbieta; Figaszewski, Zbigniew A

2018-02-25

Human skin provides the body's first line of defense against physical and environmental assaults. This study sought to determine how rutin affects the membrane electrical properties, sialic acid content, and lipid peroxidation levels of fibroblast membranes after disruption by ultraviolet (UV) radiation. Changes in cell function may affect the basal electrical surface properties of cell membranes, and changes can be detected by electrokinetic measurements. The charge density of the fibroblast membrane surface was measured as a function of pH. A four-component equilibrium model was used to describe the interaction between ions in solution and ions on the membrane surface. Agreement was found between experimental and theoretical charge variation curves of fibroblast cells between pH 2.5 and 8. Sialic acid content was determined by Svennerholm's resorcinol method, and lipid peroxidation was estimated by measuring the malondialdehyde level. Compared to untreated cells, ultraviolet A (UVA)- or ultraviolet B (UVB)-treated skin cell membranes exhibited higher concentrations of acidic functional groups and higher average association constants with hydroxyl ions, but lower average association constants with hydrogen ions. Moreover, our results showed that UVA and UVB radiation is associated with increased levels of sialic acid and lipid peroxidation products in fibroblasts. Rutin protected cells from some deleterious UV-associated membrane changes, including changes in electrical properties, oxidative state, and biological functions. Copyright © 2018 Elsevier B.V. All rights reserved.

Evaluation of a pulsed xenon ultraviolet disinfection system to decrease bacterial contamination in operating rooms.

PubMed

El Haddad, Lynn; Ghantoji, Shashank S; Stibich, Mark; Fleming, Jason B; Segal, Cindy; Ware, Kathy M; Chemaly, Roy F

2017-10-10

Environmental cleanliness is one of the contributing factors for surgical site infections in the operating rooms (ORs). To decrease environmental contamination, pulsed xenon ultraviolet (PX-UV), an easy and safe no-touch disinfection system, is employed in several hospital environments. The positive effect of this technology on environmental decontamination has been observed in patient rooms and ORs during the end-of-day cleaning but so far, no study explored its feasibility between surgical cases in the OR. In this study, 5 high-touch surfaces in 30 ORs were sampled after manual cleaning and after PX-UV intervention mimicking between-case cleaning to avoid the disruption of the ORs' normal flow. The efficacy of a 1-min, 2-min, and 8-min cycle were tested by measuring the surfaces' contaminants by quantitative cultures using Tryptic Soy Agar contact plates. We showed that combining standard between-case manual cleaning of surfaces with a 2-min cycle of disinfection using a portable xenon pulsed ultraviolet light germicidal device eliminated at least 70% more bacterial load after manual cleaning. This study showed the proof of efficacy of a 2-min cycle of PX-UV in ORs in eliminating bacterial contaminants. This method will allow a short time for room turnover and a potential reduction of pathogen transmission to patients and possibly surgical site infections.

THE MUSCLES TREASURY SURVEY. II. INTRINSIC LY α AND EXTREME ULTRAVIOLET SPECTRA OF K AND M DWARFS WITH EXOPLANETS

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

Youngblood, Allison; France, Kevin; Loyd, R. O. Parke

2016-06-20

The ultraviolet (UV) spectral energy distributions (SEDs) of low-mass (K- and M-type) stars play a critical role in the heating and chemistry of exoplanet atmospheres, but are not observationally well-constrained. Direct observations of the intrinsic flux of the Ly α line (the dominant source of UV photons from low-mass stars) are challenging, as interstellar H i absorbs the entire line core for even the closest stars. To address the existing gap in empirical constraints on the UV flux of K and M dwarfs, the MUSCLES Hubble Space Telescope Treasury Survey has obtained UV observations of 11 nearby M and Kmore » dwarfs hosting exoplanets. This paper presents the Ly α and extreme-UV spectral reconstructions for the MUSCLES targets. Most targets are optically inactive, but all exhibit significant UV activity. We use a Markov Chain Monte Carlo technique to correct the observed Ly α profiles for interstellar absorption, and we employ empirical relations to compute the extreme-UV SED from the intrinsic Ly α flux in ∼100 Å bins from 100–1170 Å. The reconstructed Ly α profiles have 300 km s{sup −1} broad cores, while >1% of the total intrinsic Ly α flux is measured in extended wings between 300 and 1200 km s{sup −1}. The Ly α surface flux positively correlates with the Mg ii surface flux and negatively correlates with the stellar rotation period. Stars with larger Ly α surface flux also tend to have larger surface flux in ions formed at higher temperatures, but these correlations remain statistically insignificant in our sample of 11 stars. We also present H i column density measurements for 10 new sightlines through the local interstellar medium.« less

Chemical films and monolayers on the water surface and their interactions with ultraviolet radiation: a pilot investigation

NASA Astrophysics Data System (ADS)

Schouten, Peter; Lemckert, Charles; Turnbull, David; Parisi, Alfio; Downs, Nathan; Underhill, Ian; Turner, Geoff

2011-06-01

Over the past 50 years numerous types of chemical films and monolayers have been deployed on top of a wide variety of water reserves in an endeavour to reduce evaporation. To date very little knowledge has been assimilated on how these chemical films and monolayers, once applied to a water surface, influence the underwater UV light field and, in turn, the delicate ecosystems that exist in aquatic environments. This manuscript presents underwater UV exposure profiles weighted to the DNA damage action spectrum measured under an octadecanol/hexadecanol/lime chemical film mixture, a silicone-based chemical film and an octadecanol monolayer applied to the water surface. UV transmission and absorption properties were also evaluated for each of these chemical films and monolayers. From this it was found that when chemical films/monolayers are applied to surface water they can reduce the penetration of biologically effective UV into the water column by up to 85% at a depth as small as 1 cm. This could have a positive influence on the aquatic ecosystem, as harmful UV radiation may be prevented from reaching and consequently damaging a variety of life forms or it could have a negative effect by potentially stopping aquatic organisms from adapting to solar ultraviolet radiation over extended application intervals. Additionally, there is currently no readily applicable system or technique available to readily detect or visualize chemical films and monolayers on the water surface. To overcome this problem a new method of monolayer and chemical film visualization, using a UV camera system, is detailed and tested and its applicability for usage in both laboratory-based trials and real-world operations is evaluated.

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

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

Orth, A.B.; Teramura, A.H.; Sisler, H.D.

1990-09-01

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

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

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

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 dosemore » (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.« less

Ultraviolet absorbing compounds provide a rapid response mechanism for UV protection in some reef fish.

PubMed

Braun, C; Reef, R; Siebeck, U E

2016-07-01

The external mucus surface of reef fish contains ultraviolet absorbing compounds (UVAC), most prominently Mycosporine-like Amino Acids (MAAs). MAAs in the external mucus of reef fish are thought to act as sunscreens by preventing the damaging effects of ultraviolet radiation (UVR), however, direct evidence for their protective role has been missing. We tested the protective function of UVAC's by exposing fish with naturally low, Pomacentrus amboinensis, and high, Thalassoma lunare, mucus absorption properties to a high dose of UVR (UVB: 13.4W∗m(-2), UVA: 6.1W∗m(-2)) and measuring the resulting DNA damage in the form of cyclobutane pyrimidine dimers (CPDs). For both species, the amount of UV induced DNA damage sustained following the exposure to a 1h pulse of high UVR was negatively correlated with mucus absorbance, a proxy for MAA concentration. Furthermore, a rapid and significant increase in UVAC concentration was observed in P. amboinensis following UV exposure, directly after capture and after ten days in captivity. No such increase was observed in T. lunare, which maintained relatively high levels of UV absorbance at all times. P. amboinensis, in contrast to T. lunare, uses UV communication and thus must maintain UV transparent mucus to be able to display its UV patterns. The ability to rapidly alter the transparency of mucus could be an important adaptation in the trade off between protection from harmful UVR and UV communication. Copyright © 2016 Elsevier B.V. All rights reserved.

Ultraviolet Light-Assisted Copper Oxide Nanowires Hydrogen Gas Sensor

NASA Astrophysics Data System (ADS)

Sihar, Nabihah; Tiong, Teck Yaw; Dee, Chang Fu; Ooi, Poh Choon; Hamzah, Azrul Azlan; Mohamed, Mohd Ambri; Majlis, Burhanuddin Yeop

2018-05-01

We fabricated copper oxide nanowires (CuO NWs) ultraviolet (UV) light-assisted hydrogen gas sensor. The fabricated sensor shows promising sensor response behavior towards 100 ppm of H2 at room temperature and elevated temperature at 100 °C when exposed to UV light (3.0 mW/cm2). One hundred-cycle device stability test has been performed, and it is found that for sample elevated at 100 °C, the UV-activated sample achieved stability in the first cycle as compared to the sample without UV irradiation which needed about 10 cycles to achieve stability at the initial stage, whereas the sample tested at room temperature was able to stabilize with the aid of UV irradiation. This indicates that with the aid of UV light, after some "warming up" time, it is possible for the conventional CuO NW sensor which normally work at elevated temperature to function at room temperature because UV source is speculated to play a dominant role to increase the interaction of the surface of CuO NWs and hydrogen gas molecules absorbed after the light exposure.

Ultraviolet Light-Assisted Copper Oxide Nanowires Hydrogen Gas Sensor.

PubMed

Sihar, Nabihah; Tiong, Teck Yaw; Dee, Chang Fu; Ooi, Poh Choon; Hamzah, Azrul Azlan; Mohamed, Mohd Ambri; Majlis, Burhanuddin Yeop

2018-05-15

We fabricated copper oxide nanowires (CuO NWs) ultraviolet (UV) light-assisted hydrogen gas sensor. The fabricated sensor shows promising sensor response behavior towards 100 ppm of H 2 at room temperature and elevated temperature at 100 °C when exposed to UV light (3.0 mW/cm 2 ). One hundred-cycle device stability test has been performed, and it is found that for sample elevated at 100 °C, the UV-activated sample achieved stability in the first cycle as compared to the sample without UV irradiation which needed about 10 cycles to achieve stability at the initial stage, whereas the sample tested at room temperature was able to stabilize with the aid of UV irradiation. This indicates that with the aid of UV light, after some "warming up" time, it is possible for the conventional CuO NW sensor which normally work at elevated temperature to function at room temperature because UV source is speculated to play a dominant role to increase the interaction of the surface of CuO NWs and hydrogen gas molecules absorbed after the light exposure.

Effects of ultraviolet irradiation on the bond strength of a composite resin adhered to stainless steel crowns.

PubMed

Baeza-Robleto, Selene J; Villa-Negrete, Dulce M; García-Contreras, René; Scougall-Vílchis, Rogelio J; Guadarrama-Quiroz, Luis J; Robles-Bermeo, Norma L

2013-01-01

A technique whereby the practitioner could improve the esthetic appearance of anterior stainless steel crowns (SSC) could provide a cost-effective alternative to more expensive commercially available preveneered SSCs, which may not be uniformly available. The purpose of this study was to evaluate the effects of ultraviolet (UV) irradiation of the metal crown surface on the shear bond strength of composite resin adhered to stainless steel crowns. Seventy extracted anterior bovine teeth randomly divided into 2 groups (n=35/group), were restored with primary maxillary left central incisor SSCs. Surface roughening with a green stone was performed on the labial surfaces, and the crowns of the experimental group were exposed to UV irradiation for 80 minutes. All samples were treated with metal-composite adhesive, followed by composite opaquer. Standardized composite blocks were bonded on the treated surfaces, and the shear bond strength was tested at 1 mm/minute. The values were recorded in MPa and statistically analyzed. The mean value of shear bond strength was significantly higher for the experimental group (19.7 ± 4.3 MPa) than the control group (16.3 ± 4.5 MPa). Ultraviolet irradiation of primary tooth stainless steel crowns significantly increased the shear bond strength of composite resin adhered to the facial surface.

The Far-UV Albedo of the Moon Determined from Dayside LAMP Observations

NASA Astrophysics Data System (ADS)

Bullock, Mark A.; Retherford, K. D.; Gladstone, R.; Greathouse, T. K.; Mandt, K. E.; Hendrix, A. R.; Feldman, P. D.; Miles, P. F.; Egan, A. F.

2013-10-01

The Lyman Alpha Mapping Project (LAMP) onboard the Lunar Reconnaissance Orbiter (LRO) has been recording far-UV photons reflected from the lunar surface almost continuously since December 2009 (Gladstone et al., 2010). One photon at a time, LAMP builds up spectra from 575 to 1965 Å with a resolution of 26 Å. We will present 3 years of accumulated LAMP lunar dayside spectral maps and derive the lunar geometric albedo spectrum for a range of phase angles. These LAMP observations can thus be used to reconstruct the lunar far-UV photometric function and refine photometric models of the lunar surface (Hapke, 1963; Lucke et al., 1976). We will also compare LAMP lunar dayside albedo with the albedo from 820-1840 Å obtained by the Hopkins Ultraviolet Telescope (HUT) on the March 1995 Astro-2 Space Shuttle mission (Henry et al., 1995). The improved lunar photometric functions from our analysis of LAMP albedo spectra will enable a better quantitative assessment of how phase angle and composition affect the Moon’s reflectance in the far-UV. Gladstone, G. R., Stern, S. A., Retherford, K. D., Black, R. K., Slater, D. C., Davis, M. W., Versteeg, M. H., Persson, K. B., Parker, J. W., Kaufmann, D. E., Egan, A. F., Greathouse, T. K., Feldman, P. D., Hurley, D., Pryor, W. R., Hendrix, A. R., 2010. LAMP: The lyman alpha mapping project on NASA's lunar reconnaissance orbiter mission. Space Science Reviews. 150, 161-181. Hapke, B. W., 1963. A theoretical photometric function for the lunar surface. Journal of Geophysical Research. 68, 4571-4586. Henry, R. C., Feldman, P. D., Kruk, J. W., Davidsen, A. F., Durrance, S. T., 1995. Ultraviolet Albedo of the Moon with the Hopkins Ultraviolet Telescope. The Astrophysical Journal Letters. 454, L69. Lucke, R. L., Henry, R. C., Fastie, W. G., 1976. Far-ultraviolet albedo of the moon. The Astronomical Journal. 81, 1162-1169.

Photosynthetic carbon reduction by seagrasses exposed to ultraviolet A radiation

NASA Technical Reports Server (NTRS)

1979-01-01

The seagrasses Halophila engelmannii, Halodule wrightii, and Syringodium filiforme were examined for their intrinsic sensitivity to ultraviolet-A-UV-A and ultraviolet-B-UV-B radiation. The effect of UV-A on photosynthetically active radiation (PAR) was also determined. Ultraviolet-A and ultraviolet-B were studied with emphasis on the greater respective environmental consequence in terms of seagrass distribution and abundance. Results indicate that an intrinsic sensitivity to UV-A alone is apparent only in Halophila, while net photosynthesis in Halodule and Syringodium seems unaffected by the level of UV-A provided. The sensitivity of Halophila to UV-A in the absense of (PAR) indicates that the photosynthetic reaction does not need to be in operation for damage to occur. Other significant results are reported.

Ultraviolet Spectroscopy of the Surfaces of the Inner Icy Saturnian Satellites

NASA Astrophysics Data System (ADS)

Hendrix, A. R.; Hansen, C. J.

2008-12-01

The Cassini mission has provided a unique opportunity to make high-resolution, multi-spectral measurements of Saturn's icy moons, to investigate their surface compositions, processes and evolution. Here we present results from the Ultraviolet Imaing Spectrograph (UVIS). This instrument allows for the first measurements of the icy satellites in the extreme ultraviolet (EUV) to far-ultraviolet (FUV) wavelength range. The icy satellites of the Saturn system exhibit a remarkable amount of variability: Dark, battered Phoebe orbiting at a distant 200 RS, black-and-white Iapetus, the wispy streaks of Dione, cratered Rhea and Mimas, bright Tethys and geologically active Enceladus. Phoebe, Iapetus and Hyperion all orbit largely outside Saturn's magnetosphere, while the inner icy satellites Mimas, Enceladus, Dione Tethys and Rhea all orbit within the magnetosphere. Furthermore, the inner icy satellites all orbit within the E-ring - so the extent of exogenic effects on these icy satellites is wide-ranging. We present an overview of UVIS results from Tethys, Dione, Mimas, Enceladus and Rhea, focusing on surface investigations. We expect that the UV signatures of these icy satellites are strongly influenced not only by their water ice composition, but by external effects and magnetospheric environments. We study the FUV reflectance spectra to learn about the surface composition, map out water ice grain size variations, investigate effects of coating by E-ring grains, examine disk-resolved and hemispheric compositional and brightness variations, and investigate the presence of radiation products. This is new work: FUV spectra of surfaces have not been well-studied in the past. Spectra of the inner icy moons have been used to better develop spectral models, to further understand existing lab data of water ice and to help with understanding instrument performance. Analysis is challenged by a lack of laboratory data in this wavelength region, but intriguing results are being found. We find that the FUV albedo is a critical tie- point to understand the composition of these moons -- important absorptions occur in the NUV-visible region. We present disk-integrated hemispherical reflectance spectra, and show that while Tethys and Dione exhibit strong UV leading-trailing differences, Mimas, Enceladus and Rhea do not. In the UV, Mimas is nearly as bright as Enceladus. Tethys is surprisingly dark in the UV. The visible-wavelength leading-trailing hemisphere albedo differences can be attributed to coating by E-ring grains; in the UV, a process appears to darken the trailing hemisphere of Tethys. We also investigate disk-resolved Enceladus spectra to understand spectral differences between the south polar tiger stripe region and elsewhere on the surface.

Effect of ultraviolet light irradiation period on bond strengths between fiber-reinforced composite post and core build-up composite resin.

PubMed

Asakawa, Yuya; Takahashi, Hidekazu; Iwasaki, Naohiko; Kobayashi, Masahiro

2014-01-01

The aim of the present study was to characterize the effects of the ultraviolet light (UV) irradiation period on the bond strength of fiber-reinforced composite (FRC) posts to core build-up resin. Three types of FRC posts were prepared using polymethyl methacrylate, urethane dimethacrylate, and epoxy resin. The surfaces of these posts were treated using UV irradiation at a distance of 15 mm for 0 to 600 s. The pull-out bond strength was measured and analyzed with the Dunnett's comparison test (α=0.05). The bond strengths of the post surfaces without irradiation were 6.9 to 7.4 MPa; those after irradiation were 4.2 to 26.1 MPa. The bond strengths significantly increased after 15 to 120-s irradiation. UV irradiation on the FRC posts improved the bond strengths between the FRC posts and core build-up resin regardless of the type of matrix resin.

Sulfur, ultraviolet radiation, and the early evolution of life

NASA Technical Reports Server (NTRS)

Kasting, J. F.; Zahnle, K. J.; Pinto, J. P.; Young, A. T.

1989-01-01

The present biosphere is shielded from harmful solar near ultraviolet (UV) radiation by atmospheric ozone. It is suggested that elemental sulfur vapor could have played a similar role in an anoxic, ozone-free, primitive atmosphere. Sulfur vapor would have been produced photochemically from volcanogenic SO2 and H2S. It is composed of ring molecules, primarily S8, that absorb strongly throughout the near UV, yet are expected to be relatively stable against photolysis and chemical attack. It is also insoluble in water and would thus have been immune to rainout or surface deposition over the oceans. Since the concentration of S8 in the primitive atmosphere would have been limited by its saturation vapor pressure, surface temperatures of 45 C or higher, corresponding to carbon dioxide partial pressures exceeding 2 bars, are required to sustain an effective UV screen. A warm, sulfur-rich, primitive atmosphere is consistent with inferences drawn from molecular phylogeny, which suggest that some of the earliest organisms were thermophilic bacteria that metabolized elemental sulfur.

Modeling UV-B Effects on Primary Production Throughout the Southern Ocean Using Multi-Sensor Satellite Data

NASA Technical Reports Server (NTRS)

Lubin, Dan

2001-01-01

This study has used a combination of ocean color, backscattered ultraviolet, and passive microwave satellite data to investigate the impact of the springtime Antarctic ozone depletion on the base of the Antarctic marine food web - primary production by phytoplankton. Spectral ultraviolet (UV) radiation fields derived from the satellite data are propagated into the water column where they force physiologically-based numerical models of phytoplankton growth. This large-scale study has been divided into two components: (1) the use of Total Ozone Mapping Spectrometer (TOMS) and Special Sensor Microwave Imager (SSM/I) data in conjunction with radiative transfer theory to derive the surface spectral UV irradiance throughout the Southern Ocean; and (2) the merging of these UV irradiances with the climatology of chlorophyll derived from SeaWiFS data to specify the input data for the physiological models.

High-sensitivity silicon ultraviolet p+-i-n avalanche photodiode using ultra-shallow boron gradient doping

DOE PAGES

Xia, Zhenyang; Zang, Kai; Liu, Dong; ...

2017-08-21

Photo detection of ultraviolet (UV) light remains a challenge since the penetration depth of UV light is limited to the nanometer scale. Therefore, the doping profile and electric field in the top nanometer range of the photo detection devices become critical. Traditional UV photodetectors usually use a constant doping profile near the semiconductor surface, resulting in a negligible electric field, which limits the photo-generated carrier collection efficiency of the photodetector. Here, we demonstrate, via the use of an optimized gradient boron doping technique, that the carrier collection efficiency and photo responsivity under the UV wavelength region have been enhanced. Moreover,more » the ultrathin p+-i-n junction shows an avalanche gain of 2800 and an ultra-low junction capacitance (sub pico-farad), indicating potential applications in the low timing jitter single photon detection area.« less

High-sensitivity silicon ultraviolet p+-i-n avalanche photodiode using ultra-shallow boron gradient doping

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

Xia, Zhenyang; Zang, Kai; Liu, Dong

Photo detection of ultraviolet (UV) light remains a challenge since the penetration depth of UV light is limited to the nanometer scale. Therefore, the doping profile and electric field in the top nanometer range of the photo detection devices become critical. Traditional UV photodetectors usually use a constant doping profile near the semiconductor surface, resulting in a negligible electric field, which limits the photo-generated carrier collection efficiency of the photodetector. Here, we demonstrate, via the use of an optimized gradient boron doping technique, that the carrier collection efficiency and photo responsivity under the UV wavelength region have been enhanced. Moreover,more » the ultrathin p+-i-n junction shows an avalanche gain of 2800 and an ultra-low junction capacitance (sub pico-farad), indicating potential applications in the low timing jitter single photon detection area.« less

Inactivation of Escherichia coli on tomatoes using a ultraviolet(LED)light

USDA-ARS?s Scientific Manuscript database

The recently developed UV LED has been shown effective at inactivating bacteria in water, but its ability to inactivate bacteria on foods is unknown. Escherichia coli in solution and dried on the surface of tomatoes was exposed to 255 nm UV from a LED, with a forward voltage of 6.5 V operating at 20...

Inactivation of uropathogenic Escherichia coli in ground chicken meat using high pressure processing and gamma radiation, and in purge and chicken meat surfaces by ultraviolet light

USDA-ARS?s Scientific Manuscript database

Uropathogenic Escherichia coli (UPEC) are common contaminants in meat and poultry. Nonthermal food safety intervention technologies used to improve safety and shelf-life of both human and pet foods can include high pressure processing (HPP), ionizing (gamma) radiation (GR), and ultraviolet light (UV...

Near-ultraviolet laser diodes for brilliant ultraviolet fluorophore excitation.

PubMed

Telford, William G

2015-12-01

Although multiple lasers are now standard equipment on most modern flow cytometers, ultraviolet (UV) lasers (325-365 nm) remain an uncommon excitation source for cytometry. Nd:YVO4 frequency-tripled diode pumped solid-state lasers emitting at 355 nm are now the primary means of providing UV excitation on multilaser flow cytometers. Although a number of UV excited fluorochromes are available for flow cytometry, the cost of solid-state UV lasers remains prohibitively high, limiting their use to all but the most sophisticated multilaser instruments. The recent introduction of the brilliant ultraviolet (BUV) series of fluorochromes for cell surface marker detection and their importance in increasing the number of simultaneous parameters for high-dimensional analysis has increased the urgency of including UV sources in cytometer designs; however, these lasers remain expensive. Near-UV laser diodes (NUVLDs), a direct diode laser source emitting in the 370-380 nm range, have been previously validated for flow cytometric analysis of most UV-excited probes, including quantum nanocrystals, the Hoechst dyes, and 4',6-diamidino-2-phenylindole. However, they remain a little-used laser source for cytometry, despite their significantly lower cost. In this study, the ability of NUVLDs to excite the BUV dyes was assessed, along with their compatibility with simultaneous brilliant violet (BV) labeling. A NUVLD emitting at 375 nm was found to excite most of the available BUV dyes at least as well as a UV 355 nm source. This slightly longer wavelength did produce some unwanted excitation of BV dyes, but at sufficiently low levels to require minimal additional compensation. NUVLDs are compact, relatively inexpensive lasers that have higher power levels than the newest generation of small 355 nm lasers. They can, therefore, make a useful, cost-effective substitute for traditional UV lasers in multicolor analysis involving the BUV and BV dyes. Published 2015 Wiley Periodicals Inc. on behalf of ISAC.

Distribution and nature of UV absorbers on Trition's surface

NASA Technical Reports Server (NTRS)

Stern, S. Alan

1995-01-01

Substantial evidence suggests that a UV (ultraviolet) Spectrally Absorbing Material (UV-SAM) exists on Triton's surface. This evidence is found in the positive slope in Triton's spectrum from the UV to the near-IR, and the increasing contrast in Triton's light curve in the blue and UV. Although it is now widely-thought that UV-SAM's exist on Triton, little is known about their distribution and spectral properties. The goal of this NDAP Project is to determine the spatial distribution and geological context of the UV-SAM material. We hope to determine if UV-SAM's on Triton are correlated with geologic wind streaks, craters, calderas, geomorphic/topographic units, regions containing (or lacking) volatile frosts, or some other process (e.g., magnetospheric interactions). Once the location and distribution of UV-SAM's has been determined, further constraints on their composition can be made by analyzing the spectrographic data set. To accomplish these goals, various data sets will be used, including Voyager 2 UV and visible images of Triton's surface, IUE and HST spectra of Triton, and a geologic map of the surface based on Voyager 2 and spectrophotometric data. The results of this research will be published in the planetary science literature.

Universal liquid-phase laser fabrication of various nano-metals encapsulated by ultrathin carbon shells for deep-UV plasmonics.

PubMed

Yu, Miao; Yang, Chao; Li, Xiao-Ming; Lei, Tian-Yu; Sun, Hao-Xuan; Dai, Li-Ping; Gu, Yu; Ning, Xue; Zhou, Ting; Wang, Chao; Zeng, Hai-Bo; Xiong, Jie

2017-06-29

The exploration of localized surface plasmon resonance (LSPR) beyond the usual visible waveband, for example within the ultraviolet (UV) or deep-ultraviolet (D-UV) regions, is of great significance due to its unique applications in secret communications and optics. However, it is still challenging to universally synthesize the corresponding metal nanostructures due to their high activity. Herein, we report a universal, eco-friendly, facile and rapid synthesis of various nano-metals encapsulated by ultrathin carbon shells, significantly with a remarkable deep-UV LSPR characteristic, via a liquid-phase laser fabrication method. Firstly, a new generation of the laser ablation in liquid (LAL) method has been developed with an emphasis on the elaborate selection of solvents to generate ultrathin carbon shells, and hence to stabilize the formed metal nanocrystals. As a result, a series of metal@carbon nanoparticles (NPs), including Cr@C, Ti@C, Fe@C, V@C, Al@C, Sn@C, Mn@C and Pd@C, can be fabricated by this modified LAL method. Interestingly, these NPs exhibit LSPR peaks in the range of 200-330 nm, which are very rare for localized surface plasmon resonance. Consequently, the UV plasmonic effects of these metal@carbon NPs were demonstrated both by the observed enhancement in UV photoluminescence (PL) from the carbon nanoshells and by the improvement of the photo-responsivity of UV GaN photodetectors. This work could provide a universal method for carbon shelled metal NPs and expand plasmonics into the D-UV waveband.

Evaluation of a teflon based ultraviolet light system on the disinfection of water in a textile air washer

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

Smith, J.E.; Whisnant, R.B.

The report provides an in-depth evaluation of an ultraviolet (UV) disinfection unit as applied to the treatment of cooling water in a textile air washer system. The UV unit tests used a teflon tube to transport the aquatic phase. The unit reduced microbial populations and maintained an average level of 10,000 Colony formed unites/mL for the 6-month testing period, without the addition of biocides. No cleaning or other maintenance was required of the wetted surfaces during the testing period. Slime deposits observed on walls of the air washer during chemical treatment were also eliminated. The UV unit can be utilizedmore » on both cooling towers and air washers without extensive installation.« less

Ultraviolet Imaging with Low Cost Smartphone Sensors: Development and Application of a Raspberry Pi-Based UV Camera

PubMed Central

Wilkes, Thomas C.; McGonigle, Andrew J. S.; Pering, Tom D.; Taggart, Angus J.; White, Benjamin S.; Bryant, Robert G.; Willmott, Jon R.

2016-01-01

Here, we report, for what we believe to be the first time, on the modification of a low cost sensor, designed for the smartphone camera market, to develop an ultraviolet (UV) camera system. This was achieved via adaptation of Raspberry Pi cameras, which are based on back-illuminated complementary metal-oxide semiconductor (CMOS) sensors, and we demonstrated the utility of these devices for applications at wavelengths as low as 310 nm, by remotely sensing power station smokestack emissions in this spectral region. Given the very low cost of these units, ≈ USD 25, they are suitable for widespread proliferation in a variety of UV imaging applications, e.g., in atmospheric science, volcanology, forensics and surface smoothness measurements. PMID:27782054

Impact of UV irradiation on multiwall carbon nanotubes in nanocomposites: formation of entangled surface layer and mechanisms of release resistance

PubMed Central

Nguyen, Tinh; Petersen, Elijah J.; Pellegrin, Bastien; Gorham, Justin M.; Lam, Thomas; Zhao, Minhua; Sung, Lipiin

2017-01-01

Multiwall carbon nanotubes (MWCNTs) are nanofillers used in consumer and structural polymeric products to enhance a variety of properties. Under weathering, the polymer matrix will degrade and the nanofillers may be released from the products potentially impacting ecological or human health. In this study, we investigated the degradation of a 0.72 % (by mass) MWCNT/amine-cured epoxy nanocomposite irradiated with high intensity ultraviolet (UV) light at various doses, the effects of UV exposure on the surface accumulation and potential release of MWCNTs, and possible mechanisms for the release resistance of the MWCNT surface layer formed on nanocomposites by UV irradiation. Irradiated samples were characterized for chemical degradation, mass loss, surface morphological changes, and MWCNT release using a variety of analytical techniques. Under 295 nm to 400 nm UV radiation up to a dose of 4865 MJ/m2, the nanocomposite matrix underwent photodegradation, resulting in formation of a dense, entangled MWCNT network structure on the surface. However, no MWCNT release was detected, even at very high UV doses, suggesting that the MWCNT surface layer formed from UV irradiation of polymer nanocomposites resist release. Four possible release resistance mechanisms of the UV-induced MWCNT surface layer are presented and discussed. PMID:28603293

Effect of Ultraviolet Light Irradiation Combined with Riboflavin on Different Bacterial Pathogens from Ocular Surface Infection.

PubMed

Shen, Jing; Liang, Qingfeng; Su, Guanyu; Zhang, Yang; Wang, Zhiqun; Liang, Hong; Baudouin, Christophe; Labbé, Antoine

2017-01-01

In order to study Staphylococcus epidermis and Staphylococcus aureus in vitro viability after the exposure to ultraviolet (UV) light and riboflavin, twelve strains of Staphylococcus epidermis and twelve strains of Staphylococcus aureus were isolated from patients with bacterial keratitis. The growth situation of Staphylococcus epidermidis and Staphylococcus aureus under different experimental conditions was qualitatively observed. The number of colonies surviving bacteria was counted under different UV light power and different exposure time. The experiment showed that there was no inhibition effect on the growth of bacteria using riboflavin alone. In UV alone group and UV-riboflavin group, inhibition effect on the bacteria growth was found. The UV-riboflavin combination had better inhibition effect on bacteria than UV irradiation alone. The amount of bacteria in the UV-riboflavin group was decreased by 99.1%~99.5% and 54.8%~64.6% in the UV alone group, when the UV light power was 10.052 mW/cm 2 and the irradiation time was 30 min. Moreover, with the increase of the UV power or irradiation time, the survival rates of bacteria were rapidly reduced. Compared with Staphylococcus aureus , Staphylococcus epidermis was more easily to be killed under the action of UV light combined with riboflavin.

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

PubMed

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

2017-10-01

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

Vulnerability and behavioral response to ultraviolet radiation in the components of a foliar mite prey-predator system.

PubMed

Tachi, Fuyuki; Osakabe, Masahiro

2012-12-01

Ambient ultraviolet-B (UVB) radiation impacts plant-dwelling arthropods including herbivorous and predatory mites. However, the effects of UVB on prey-predator systems, such as that between the herbivorous spider mite and predatory phytoseiid mite, are poorly understood. A comparative study was conducted to determine the vulnerability and behavioral responses of these mites to ultraviolet (UV) radiation. First, we analyzed dose-response (cumulative irradiance-mortality) curves for the eggs of phytoseiid mites (Neoseiulus californicus, Neoseiulus womersleyi, and Phytoseiulus persimilis) and the spider mite (Tetranychus urticae) to UVB radiation from a UV lamp. This indicated that the phytoseiid mites were more vulnerable than the spider mite, although P. persimilis was slightly more tolerant than the other two phytoseiid mites. Second, we compared the avoidance behavior of adult female N. californicus and two spider mite species (T. urticae, a lower leaf surface user; Panonychus citri, an upper leaf surface user) in response to solar UV and visible light. N. californicus actively avoided both types of radiation, whereas P. citri showed only minimal avoidance behavior. T. urticae actively avoided UV as well as N. californicus but exhibited a slow response to visible light as well as P. citri. Such variation in vulnerability and avoidance behavior accounts for differences in the species adaptations to solar UVB radiation. This may be the primary factor determining habitat use among these mites on host plant leaves, subsequently affecting accessibility by predators and also intraguild competition.

Vulnerability and behavioral response to ultraviolet radiation in the components of a foliar mite prey-predator system

NASA Astrophysics Data System (ADS)

Tachi, Fuyuki; Osakabe, Masahiro

2012-12-01

Ambient ultraviolet-B (UVB) radiation impacts plant-dwelling arthropods including herbivorous and predatory mites. However, the effects of UVB on prey-predator systems, such as that between the herbivorous spider mite and predatory phytoseiid mite, are poorly understood. A comparative study was conducted to determine the vulnerability and behavioral responses of these mites to ultraviolet (UV) radiation. First, we analyzed dose-response (cumulative irradiance-mortality) curves for the eggs of phytoseiid mites ( Neoseiulus californicus, Neoseiulus womersleyi, and Phytoseiulus persimilis) and the spider mite ( Tetranychus urticae) to UVB radiation from a UV lamp. This indicated that the phytoseiid mites were more vulnerable than the spider mite, although P. persimilis was slightly more tolerant than the other two phytoseiid mites. Second, we compared the avoidance behavior of adult female N. californicus and two spider mite species ( T. urticae, a lower leaf surface user; Panonychus citri, an upper leaf surface user) in response to solar UV and visible light. N. californicus actively avoided both types of radiation, whereas P. citri showed only minimal avoidance behavior. T. urticae actively avoided UV as well as N. californicus but exhibited a slow response to visible light as well as P. citri. Such variation in vulnerability and avoidance behavior accounts for differences in the species adaptations to solar UVB radiation. This may be the primary factor determining habitat use among these mites on host plant leaves, subsequently affecting accessibility by predators and also intraguild competition.

Ultraviolet spectrophotometer for measuring columnar atmospheric ozone from aircraft

NASA Technical Reports Server (NTRS)

Hanser, F. A.; Sellers, B.; Briehl, D. C.

1978-01-01

An ultraviolet spectrophotometer (UVS) to measure downward solar fluxes from an aircraft or other high altitude platform is described. The UVS uses an ultraviolet diffuser to obtain large angular response with no aiming requirement, a twelve-position filter wheel with narrow (2-nm) and broad (20-nm) bandpass filters, and an ultraviolet photodiode. The columnar atmospheric ozone above the UVS (aircraft) is calculated from the ratios of the measured ultraviolet fluxes. Comparison with some Dobson station measurements gives agreement to 2%. Some UVS measured ozone profiles over the Pacific Ocean for November 1976 are shown to illustrate the instrument's performance.

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

PubMed

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

2016-01-01

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

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

NASA Technical Reports Server (NTRS)

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

1992-01-01

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

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

NASA Technical Reports Server (NTRS)

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

1992-01-01

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

The Effects of Ultraviolet Radiation on Attached Wetland Algae and Bacteria

NASA Astrophysics Data System (ADS)

Thomas, V. K.; Kuehn, K. A.; Francoeur, S. N.

2005-05-01

Despite the well-known increases in ultraviolet radiation (UV-R) reaching the Earth's surface due to the destruction of the ozone layer, little is known about effects of UV-R on wetland periphyton. To study the effects of UV-R on wetland periphyton, artificial substrata were placed under acrylic mesocosms in the Paint Creek Wetland, Ypsilanti, MI. One treatment mesocosm excluded light in the UV range (<340nm) and the other allowed the passage of full light. Periphyton attached to artificial substrata was collected on 4 dates during August and September 2004 and analyzed for Chlorophyll a, ash-free dry mass (AFDM), bacterial density, colloidal extracellular polysaccharides (EPS) and algal community composition. Over the length of the experiment the proportion of dead to live bacteria (p<0.02), EPS accrual (μgram glucose equivalents/cm2) (p=0.046), and the ratio of EPS to AFDM (p=0.027) were significantly greater in the UV-R-exposed treatment. These results suggest that ambient levels of UV-R damage periphytic bacteria and increase EPS production by periphyton.

Use of radiation in biomaterials science

NASA Astrophysics Data System (ADS)

Benson, Roberto S.

2002-05-01

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

[Light protection for xeroderma pigmentosum].

PubMed

Ettinger, M; Berneburg, M

2017-05-01

Xeroderma pigmentosum is a rare autosomal recessive disorder which is caused by germinal mutations responsible for the repair of ultraviolet (UV) radiation-induced DNA lesions. It is characterized by hypersensitivity to UV radiation, poikiloderma, ocular surface disease, and in some patients pronounced sunburn and neurological disease. Patients have a very high risk of developing ocular and skin cancer on exposed body sites. No cure is available for these patients except complete protection from all types of UV radiation.

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

NASA Technical Reports Server (NTRS)

Green, A. E. S.

1979-01-01

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

Extreme ultraviolet index due to broken clouds at a midlatitude site, Granada (southeastern Spain)

NASA Astrophysics Data System (ADS)

Antón, M.; Piedehierro, A. A.; Alados-Arboledas, L.; Wolfran, E.; Olmo, F. J.

2012-11-01

Cloud cover usually attenuates the ultraviolet (UV) solar radiation but, under certain sky conditions, the clouds may produce an enhancement effect increasing the UV levels at surface. The main objective of this paper is to analyze an extreme UV enhancement episode recorded on 16 June 2009 at Granada (southeastern Spain). This phenomenon was characterized by a quick and intense increase in surface UV radiation under broken cloud fields (5-7 oktas) in which the Sun was surrounded by cumulus clouds (confirmed with sky images). Thus, the UV index (UVI) showed an enhancement of a factor 4 in the course of only 30 min around midday, varying from 2.6 to 10.4 (higher than the corresponding clear-sky UVI value). Additionally, the UVI presented values higher than 10 (extreme erythemal risk) for about 20 min running, with a maximum value around 11.5. The use of an empirical model and the total ozone column (TOC) derived from the Global Ozone Monitoring Experiment (GOME) for the period 1995-2011 showed that the value of UVI ~ 11.5 is substantially larger than the highest index that could origin the natural TOC variations over Granada. Finally, the UV erythemal dose accumulated during the period of 20 min with the extreme UVI values under broken cloud fields was 350 J/m2 which surpass the energy required to produce sunburn of the most human skin types.

Three-dimensional characterization of extreme ultraviolet mask blank defects by interference contrast photoemission electron microscopy.

PubMed

Lin, Jingquan; Weber, Nils; Escher, Matthias; Maul, Jochen; Han, Hak-Seung; Merkel, Michael; Wurm, Stefan; Schönhense, Gerd; Kleineberg, Ulf

2008-09-29

A photoemission electron microscope based on a new contrast mechanism "interference contrast" is applied to characterize extreme ultraviolet lithography mask blank defects. Inspection results show that positioning of interference destructive condition (node of standing wave field) on surface of multilayer in the local region of a phase defect is necessary to obtain best visibility of the defect on mask blank. A comparative experiment reveals superiority of the interference contrast photoemission electron microscope (Extreme UV illumination) over a topographic contrast one (UV illumination with Hg discharge lamp) in detecting extreme ultraviolet mask blank phase defects. A depth-resolved detection of a mask blank defect, either by measuring anti-node peak shift in the EUV-PEEM image under varying inspection wavelength condition or by counting interference fringes with a fixed illumination wavelength, is discussed.

Solar-blind ultraviolet optical system design for missile warning

NASA Astrophysics Data System (ADS)

Chen, Yu; Huo, Furong; Zheng, Liqin

2015-03-01

Solar-blind region of Ultraviolet (UV) spectrum has very important application in military field. The spectrum range is from 240nm to 280nm, which can be applied to detect the tail flame from approaching missile. A solar-blind UV optical system is designed to detect the UV radiation, which is an energy system. iKon-L 936 from ANDOR company is selected as the UV detector, which has pixel size 13.5μm x 13.5 μm and active image area 27.6mm x 27.6 mm. CaF2 and F_silica are the chosen materials. The original structure is composed of 6 elements. To reduce the system structure and improve image quality, two aspheric surfaces and one diffractive optical element are adopted in this paper. After optimization and normalization, the designed system is composed of five elements with the maximum spot size 11.988μ m, which is less than the pixel size of the selected CCD detector. Application of aspheric surface and diffractive optical element makes each FOV have similar spot size, which shows the system almost meets the requirements of isoplanatic condition. If the focal length can be decreased, the FOV of the system can be enlarged further.

UV photography of the earth and the moon

NASA Technical Reports Server (NTRS)

1973-01-01

The fundamental aim of this experiment was the acquisition of ultraviolet photographs of the earth and the moon that could be used to interpret similar imagery of Mars and Venus. Venus shows no markings whatever when viewed in visible light, a phenomenon that is in keeping with its immensely thick atmosphere and perpetual cloud cover, but in the near ultraviolet, the planet exhibits low contrast markings which vary in position and appearance with time. Mars posed just the opposite problem from Venus at wavelengths below 4500 A, Mars shows very little detail, sometimes none at all, whereas at longer wavelengths, the surface is clearly visible. Occasionally observers have reported that this obscuration has lifted and the ground has become visible at the shorter wavelengths as well. Such events have been labeled blue clearings and led to the suggestion that the ultraviolet obscuration was caused by an atmospheric haze. Mariner 6 and 7 observations of Mars failed to find such a haze and lent support to the alternative view that ascribed the absence of detail on UV photographs to a simple lack of contrast between Martian surface features at these wavelengths.

Ultraviolet Thomson Scattering from Direct-Drive Coronal Plasmas

NASA Astrophysics Data System (ADS)

Henchen, R. J.; Goncharov, V. N.; Michel, D. T.; Follett, R. K.; Katz, J.; Froula, D. H.

2013-10-01

Ultraviolet (λ4 ω = 263 nm) Thomson scattering (TS) was used to probe ion-acoustic waves (IAW's) and electron plasma waves (EPW's) from direct-drive coronal plasmas. Fifty-nine drive beams (λ3 ω = 351 nm) illuminate a spherical target with a radius of ~860 μm. Advances in the ultraviolet (UV) TS diagnostic at the Omega Laser Facility provide the ability to detect deep UV photons (~190 nm) and allow access to scattered light from EPW's propagating near the 3 ω quarter-critical surface (~2.5 × 1021 cm-3) . A series of experiments studied the effects of ablator materials on coronal plasma conditions. Electron temperatures and densities were measured from 150 μm to 400 μm from the initial target surface. Standard CH shells were compared to three-layered shells consisting of Si doped CH, Si, and Be. Early analysis indicates that these multilayered targets have less hot-electron energy as a result of higher electron temperature in the coronal plasma. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

Focal brain lesions induced with ultraviolet irradiation.

PubMed

Nakata, Mariko; Nagasaka, Kazuaki; Shimoda, Masayuki; Takashima, Ichiro; Yamamoto, Shinya

2018-05-22

Lesion and inactivation methods have played important roles in neuroscience studies. However, traditional techniques for creating a brain lesion are highly invasive, and control of lesion size and shape using these techniques is not easy. Here, we developed a novel method for creating a lesion on the cortical surface via 365 nm ultraviolet (UV) irradiation without breaking the dura mater. We demonstrated that 2.0 mWh UV irradiation, but not the same amount of non-UV light irradiation, induced an inverted bell-shaped lesion with neuronal loss and accumulation of glial cells. Moreover, the volume of the UV irradiation-induced lesion depended on the UV light exposure amount. We further succeeded in visualizing the lesioned site in a living animal using magnetic resonance imaging (MRI). Importantly, we also observed using an optical imaging technique that the spread of neural activation evoked by adjacent cortical stimulation disappeared only at the UV-irradiated site. In summary, UV irradiation can induce a focal brain lesion with a stable shape and size in a less invasive manner than traditional lesioning methods. This method is applicable to not only neuroscientific lesion experiments but also studies of the focal brain injury recovery process.

Effect of Ultraviolet Irradiation of the Implant Surface on Progression of Periimplantitis--A Pilot Study in Dogs.

PubMed

Ishii, Kouken; Matsuo, Masato; Hoshi, Noriyuki; Takahashi, Shun-Suke; Kawamata, Ryota; Kimoto, Katsuhiko

2016-02-01

The objective of this study was to investigate morphologically the progression of periimplantitis around an ultraviolet (UV)-light-irradiated implant in dogs. Pure titanium implants (3.3 mm in diameter and 8 mm long) were placed into dog jawbone bilaterally. Implants on one side were irradiated with UV light for 15 minutes using a photodevice immediately before placement (UV group), whereas those on the other side were not irradiated (non-UV group). Osseointegration was confirmed 90 days after implant placement by radiography. Experimental periimplantitis was induced by the application of dental floss over 90 days. Clinical and radiographic examination and micro-computed tomography (micro-CT) were performed after 90 and 180 days, and bone resorption was measured. The bone-implant interface in tissue sections was examined by light microscopy. Bone resorption around the UV-irradiated implant was less pronounced than around the non-UV-irradiated implant in the ligature-induced periimplantitis model. Tissue section images revealed no contact and partial destruction at the bone-implant interface. Within the limitations of this preliminary investigation, it is suggested that UV-light-irradiated implants suppress spontaneous progression of periimplantitis.

Sensitivity of two salamander (Ambystoma) species to ultraviolet radiation

USGS Publications Warehouse

Calfee, R.D.; Bridges, C.M.; Little, E.E.

2006-01-01

Increased ultraviolet-B (UV-B) radiation reaching the Earth's surface has been implicated in amphibian declines. Recent studies have shown that many amphibian species have differences in sensitivity depending on developmental stage. Embryos and larvae of Ambystoma maculatum (Spotted Salamander) and larvae of Ambystoma talpoideum (Mole Salamander) were exposed to five simulated UV-B treatments in controlled laboratory experiments to determine the relative sensitivity of different lifestages. Hatching success of the embryos exceeded 95% in all treatments; however, the larvae of both species exhibited greater sensitivity to UV-B exposure. Older larvae of A. maculatum that were not exposed to UV-B as embryos were more sensitive than larvae that had hatched during exposure to UV-B. Growth of surviving larvae of A. maculatum was significantly reduced as UV-B intensity increased, whereas growth of A. talpoideum was unaffected. These results were compared to ambient UV-B conditions in natural environments. It appears that the embryo stage is relatively unaffected by UV-B levels observed in natural habitats, probably because of protection from vegetation, organic matter in the water column, oviposition depth, and egg jelly. The larval stage of these species may be at greater risk, particularly if there is an increase in UV-B radiation exposure caused by increases in water clarity and/or decreases in dissolved organic carbon.

Ultraviolet and visible radiation at Barrow, Alaska: Climatology and influencing factors on the basis of version 2 National Science Foundation network data

NASA Astrophysics Data System (ADS)

Bernhard, Germar; Booth, Charles R.; Ehramjian, James C.; Stone, Robert; Dutton, Ellsworth G.

2007-05-01

Spectral ultraviolet (UV) and visible irradiance has been measured near Barrow, Alaska (71°N, 157°W), between 1991 and 2005 with a SUV-100 spectroradiometer. The instrument is part of the U.S. National Science Foundation's UV Monitoring Network. Here we present results based on the recently produced "version 2" data release, which supersedes published "version 0" data. Cosine error and wavelength-shift corrections applied to the new version increased biologically effective UV dose rates by 0-10%. Corrected clear-sky measurements of different years are typically consistent to within ±3%. Measurements were complemented with radiative transfer model calculations to retrieve total ozone and surface albedo from measured spectra and for the separation of the different factors influencing UV and visible radiation. A climatology of UV and visible radiation was established, focusing on annual cycles, trends, and the effect of clouds. During several episodes in spring of abnormally low total ozone, the daily UV dose at 305 nm exceeded the climatological mean by up to a factor of 2.6. Typical noontime UV Indices during summer vary between 2 and 4; the highest UV Index measured was 5.0 and occurred when surface albedo was unusually high. Radiation levels in the UV-A and visible exhibit a strong spring-autumn asymmetry. Irradiance at 345 nm peaks on approximately 20 May, 1 month before the solstice. This asymmetry is caused by increased cloudiness in autumn and high albedo in spring, when the snow covered surface enhances downwelling UV irradiance by up to 57%. Clouds reduce UV radiation at 345 nm on average by 4% in March and by more than 40% in August. Aerosols reduce UV by typically 5%, but larger reductions were observed during Arctic haze events. Stratospheric aerosols from the Pinatubo eruption in 1991 enhanced spectral irradiance at 305 nm for large solar zenith angles. The year-to-year variations of spectral irradiance at 305 nm and of the UV Index are mostly caused by variations in total ozone and cloudiness. Changes in surface albedo that may occur in the future can have a marked impact on UV levels between May and July. No statistically significant trends in monthly mean noontime irradiance were found.

Hybrid 2D patterning using UV laser direct writing and aerosol jet printing of UV curable polydimethylsiloxane

NASA Astrophysics Data System (ADS)

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.

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

EPA Science Inventory

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

Ozone depletion - Ultraviolet radiation and phytoplankton biology in Antarctic waters

NASA Technical Reports Server (NTRS)

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

1992-01-01

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

A Fast Responsive Ultraviolet Sensor from mSILAR-Processed Sn-ZnO

NASA Astrophysics Data System (ADS)

Thomas, Deepu; Vijayalakshmi, K. A.; Sadasivuni, Kishor Kumar; Thomas, Ajith; Ponnamma, Deepalekshmi; Cabibihan, John-John

2017-11-01

Microwave-assisted successive ionic layer adsorption and reaction was employed to synthesize Sn-ZnO (tin-doped zinc oxide), and its sensitivity to ultraviolet radiation is compared with zinc oxide (ZnO). The sensing films were made by the dip-coated method on an indium titanium oxide glass substrate, and the sensing performance was monitored using the 300-700 nm wavelength of UV-Vis light. Excellent sensitivity and recovery were observed for the Sn-doped ZnO sensor device, especially at 380 nm wavelength of ultraviolet (UV) light (response and recovery time 2.26 s and 8.63 s, respectively, at 5 V bias voltage). The variation in photocurrent with respect to dark and light illumination atmosphere was well illustrated based on the Schottky and inter-particle network effects. Doping of Sn on ZnO nanoparticles varied the surface roughness and crystallite size as observed from scanning electron microscopic and x-ray diffraction studies. Here, we demonstrate a simple and economical fabrication technique for designing a high-performance UV light sensor. The developed device works at room temperature with high durability and stability.

GaN ultraviolet p-i-n photodetectors with enhanced deep ultraviolet quantum efficiency

NASA Astrophysics Data System (ADS)

Wang, Guosheng; Xie, Feng; Wang, Jun; Guo, Jin

2017-10-01

GaN ultraviolet (UV) p-i-n photodetectors (PDs) with a thin p-AlGaN/GaN contact layer are designed and fabricated. The PD exhibits a low dark current density of˜7 nA/cm2 under -5 V, and a zero-bias peak responsivity of ˜0.16 A/W at 360 nm, which corresponds to a maximum quantum efficiency of 55%. It is found that, in the wavelength range between 250 and 365 nm, the PD with thin p-AlGaN/GaN contact layer exhibits enhanced quantum efficiency especially in a deep-UV wavelength range, than that of the control PD with conventional thin p-GaN contact layer. The improved quantum efficiency of the PD with thin p-AlGaN/GaN contact layer in the deep-UV wavelength range is mainly attributed to minority carrier reflecting properties of thin p-AlGaN/GaN heterojunction which could reduce the surface recombination loss of photon-generated carriers and improve light current collection efficiency.

SR-71 Ship #1 - Ultraviolet Experiment

NASA Technical Reports Server (NTRS)

1994-01-01

NASA's SR-71 streaks into the twilight on a night/science flight from the Dryden Flight Research Center, Edwards, California. Mounted in the nose of the SR-71 was an ultraviolet video camera aimed skyward to capture images of stars, asteroids and comets. The science portion of the flight is a project of the Jet Propulsion Laboratory, Pasadena, California. Two SR-71 aircraft have been used by NASA as test beds for high-speed and high-altitude aeronautical research. One early research project flown on one of Dryden's SR-71s consisted of a proposal for a series of flights using the SR-71 as a science camera platform for the Jet Propulsion Laboratory (JPL) of the California Institute of Technology, which operates under contract to NASA in much the way that NASA centers do. In March 1993, an upward-looking ultraviolet (UV) video camera placed in the SR-71's nosebay studied a variety of celestial objects in the ultraviolet light spectrum. The SR-71 was proposed as a test bed for the experiment because it is capable of flying at altitudes above 80,000 feet for an extended length of time. Observation of ultraviolet radiation is not possible from the Earth's surface because the atmosphere's ozone layer absorbs UV rays. Study of UV radiation is important because it is known to cause skin cancer with prolonged exposure. UV radiation is also valuable to study from an astronomical perspective. Satellite study of ultraviolet radiation is very expensive. As a result, the South West Research Institute (SWRI) in Texas developed the hypothesis of using a high-flying aircraft such as the SR-71 to conduct UV observations. The SR-71 is capable of flying above 90 percent of the Earth's atmosphere. The flight program was also designed to test the stability of the aircraft as a test bed for UV observation. A joint flight program was developed between the JPL and NASA's Ames-Dryden Flight Research Facility (redesignated the Dryden Flight Research Center, Edwards, California, in 1994) in conjunction with SWRI to test the hypothesis. Dryden modified the nosebay of the SR-71, creating an upward-observing window to carry SWRI's ultraviolet CCD camera so it could make observations. According to Dryden's SR-71 Project Manager Dave Lux, a single flight of the aircraft confirmed the aircraft's capability and stability as a test bed for UV observations. SWRI's principle investigator was Dr. Allen Stern.

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

PubMed

Kheyrandish, Ataollah; Mohseni, Madjid; Taghipour, Fariborz

2018-06-15

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

Unexpected Far-Ultraviolet Photometric Characteristics On Mimas

NASA Astrophysics Data System (ADS)

Royer, E. M.; Hendrix, A. R.

2013-12-01

While infrared and visible are the most common wavelength domains used to investigate planetary surfaces, ultraviolet (UV) data are significant and useful. Here, we present the first far-UV phase curves of Mimas, thus displaying another piece of the Saturnian System puzzle. Our preliminary results shows that, one more time, Mimas surface properties are far from what we was expected. Namely, we observe a leading hemisphere brighter than the trailing hemisphere at some far-UV wavelengths. We used the far-UV channel of the Cassini/UVIS instrument, ranging from 118 to 190 nm. Disk-integrated phase curves for the leading hemisphere and the trailing hemisphere, at 180nm, have been produced. Data points span from 0.5 to 163.5 degrees in phase angle. Mimas displays a leading hemisphere brighter than its trailing hemisphere, when theory and previous Voyager observations at longer wavelengths attest of a brighter trailing hemisphere due to the impact of the E-ring grains on this face of the satellite. Surprisingly, UVIS data show a very bright opposition effect on Mimas leading hemisphere, greater than what is observed on Tethys or Dione leading hemisphere at the same wavelength of 180 nm. Preliminary results of photometric properties modeling seem to indicate an important contribution of the coherent-backscattering process in the opposition surge. Exogenic processes such as bombardment by energetic electrons and/or E-ring grains are discussed to explain this unexpected surface property of Mimas.

Disinfection of Airborne Organisms by Ultraviolet-C Radiation and Sunlight

DTIC Science & Technology

2012-07-01

organisms deposited on surfaces, suspended in water , and contaminating food, all of which have been discussed elsewhere (Block, 2001). In contrast, the... water . Therefore, the primary means for organism inactivation in aerosols is ultraviolet (UV) radiation. Radiation from the sunlight is used as a...cortex is essential for reduction of the water content in the spore core and formation of a dormant spore. The cortex is degraded in spore

Effects of catalyst concentration and ultraviolet intensity on chemical mechanical polishing of GaN

NASA Astrophysics Data System (ADS)

Wang, Jie; Wang, Tongqing; Pan, Guoshun; Lu, Xinchun

2016-08-01

Effects of catalyst concentration and ultraviolet intensity on chemical mechanical polishing (CMP) of GaN were deeply investigated in this paper. Working as an ideal homogeneous substrate material in LED industry, GaN ought to be equipped with a smooth and flat surface. Taking the strong chemical stability of GaN into account, photocatalytic oxidation technology was adopted in GaN CMP process to realize efficient removal. It was found that, because of the improved reaction rate of photocatalytic oxidation, GaN material removal rate (MRR) increases by a certain extent with catalyst concentration increasing. Cross single line analysis on the surface after polishing by Phase Shift MicroXAM-3D was carried out to prove the better removal effect with higher catalyst concentration. Ultraviolet intensity field in H2O2-SiO2-based polishing system was established and simulated, revealing the variation trend of ultraviolet intensity around the outlet of the slurry. It could be concluded that, owing to the higher planarization efficiency and lower energy damage, the UV lamp of 125 W is the most appropriate lamp in this system. Based on the analysis, defects removal model of this work was proposed to describe the effects of higher catalyst concentration and higher power of UV lamp.

Evaluation of a pulsed-xenon ultraviolet room disinfection device for impact on contamination levels of methicillin-resistant Staphylococcus aureus.

PubMed

Jinadatha, Chetan; Quezada, Ricardo; Huber, Thomas W; Williams, Jason B; Zeber, John E; Copeland, Laurel A

2014-04-07

Healthcare-acquired infections with methicillin-resistant Staphylococcus aureus (MRSA) are a significant cause of increased mortality, morbidity and additional health care costs in United States. Surface decontamination technologies that utilize pulsed xenon ultraviolet light (PPX-UV) may be effective at reducing microbial burden. The purpose of this study was to compare standard manual room-cleaning to PPX-UV disinfection technology for MRSA and bacterial heterotrophic plate counts (HPC) on high-touch surfaces in patient rooms. Rooms vacated by patients that had a MRSA-positive polymerase chain reaction or culture during the current hospitalization and at least a 2-day stay were studied. 20 rooms were then treated according to one of two protocols: standard manual cleaning or PPX-UV. This study evaluated the reduction of MRSA and HPC taken from five high-touch surfaces in rooms vacated by MRSA-positive patients, as a function of cleaning by standard manual methods vs a PPX-UV area disinfection device. Colony counts in 20 rooms (10 per arm) prior to cleaning varied by cleaning protocol: for HPC, manual (mean = 255, median = 278, q1-q3 132-304) vs PPX-UV (mean = 449, median = 365, q1-q3 332-530), and for MRSA, manual (mean = 127; median = 28.5; q1-q3 8-143) vs PPX-UV (mean = 108; median = 123; q1-q3 14-183). PPX-UV was superior to manual cleaning for MRSA (adjusted incident rate ratio [IRR] = 7; 95% CI <1-41) and for HPC (IRR = 13; 95% CI 4-48). PPX-UV technology appears to be superior to manual cleaning alone for MRSA and HPC. Incorporating 15 minutes of PPX-UV exposure time to current hospital room cleaning practice can improve the overall cleanliness of patient rooms with respect to selected micro-organisms.

Evaluation of a pulsed-xenon ultraviolet room disinfection device for impact on contamination levels of methicillin-resistant Staphylococcus aureus

PubMed Central

2014-01-01

Background Healthcare-acquired infections with methicillin-resistant Staphylococcus aureus (MRSA) are a significant cause of increased mortality, morbidity and additional health care costs in United States. Surface decontamination technologies that utilize pulsed xenon ultraviolet light (PPX-UV) may be effective at reducing microbial burden. The purpose of this study was to compare standard manual room-cleaning to PPX-UV disinfection technology for MRSA and bacterial heterotrophic plate counts (HPC) on high-touch surfaces in patient rooms. Methods Rooms vacated by patients that had a MRSA-positive polymerase chain reaction or culture during the current hospitalization and at least a 2-day stay were studied. 20 rooms were then treated according to one of two protocols: standard manual cleaning or PPX-UV. This study evaluated the reduction of MRSA and HPC taken from five high-touch surfaces in rooms vacated by MRSA-positive patients, as a function of cleaning by standard manual methods vs a PPX-UV area disinfection device. Results Colony counts in 20 rooms (10 per arm) prior to cleaning varied by cleaning protocol: for HPC, manual (mean = 255, median = 278, q1-q3 132–304) vs PPX-UV (mean = 449, median = 365, q1-q3 332–530), and for MRSA, manual (mean = 127; median = 28.5; q1-q3 8–143) vs PPX-UV (mean = 108; median = 123; q1-q3 14–183). PPX-UV was superior to manual cleaning for MRSA (adjusted incident rate ratio [IRR] = 7; 95% CI <1-41) and for HPC (IRR = 13; 95% CI 4–48). Conclusion PPX-UV technology appears to be superior to manual cleaning alone for MRSA and HPC. Incorporating 15 minutes of PPX-UV exposure time to current hospital room cleaning practice can improve the overall cleanliness of patient rooms with respect to selected micro-organisms. PMID:24708734

Ultraviolet safety assessments of insect light traps.

PubMed

Sliney, David H; Gilbert, David W; Lyon, Terry

2016-01-01

Near-ultraviolet (UV-A: 315-400 nm), "black-light," electric lamps were invented in 1935 and ultraviolet insect light traps (ILTs) were introduced for use in agriculture around that time. Today ILTs are used indoors in several industries and in food-service as well as in outdoor settings. With recent interest in photobiological lamp safety, safety standards are being developed to test for potentially hazardous ultraviolet emissions. A variety of UV "Black-light" ILTs were measured at a range of distances to assess potential exposures. Realistic time-weighted human exposures are shown to be well below current guidelines for human exposure to ultraviolet radiation. These UV-A exposures would be far less than the typical UV-A exposure in the outdoor environment. Proposals are made for realistic ultraviolet safety standards for ILT products.

In-Field Diffuse Ultraviolet Spectroscopy and Imaging of the Stardust Sample Return Capsule

NASA Technical Reports Server (NTRS)

Pugel, D. Elizabeth; Stackpoole, Mairead; McNamara, Karen; Schwartz, C.; Warren, J.; Kontinos, Dean

2008-01-01

In-field diffuse Ultraviolet (UV) spectroscopy and imaging systems were developed for the purposes of evaluating the surface chemical composition of spacecraft thermal control coatings and materials. The investigation of these systems and the compilation of an associated UV reflectance and luminescence database were conducted using the Stardust Sample Return Capsule (SRC), located at the Johnson Space Center. Spectral responses of the surfaces of the Stardust forebody and aftbody in both reflectance and fluorescence modes were examined post-flight. In this paper, we report on two primary findings of in-field diffuse UV spectroscopy and imaging: (1) deduction of the thermal history of thermal control coatings of the forebody and (2) bond line variations in the aftbody. In the forebody, the thermal history of thermal control coatings may be deduced from the presence of particular semiconducting defect states associated with ZnO, a common emissivity constituent in thermal control coatings. A spatial dependence of this history was mapped for these regions. In the aftbody, luminescing defect states, associated with Si and SiO2 color centers were found along regions of bond variability.

Photo-enhanced toxicity of fluoranthene to Gulf of Mexico marine organisms at different larval ages and ultraviolet light intensities.

PubMed

Finch, Bryson E; Stubblefield, William A

2016-05-01

Significant increases in toxicity have been observed as a result of polycyclic aromatic hydrocarbon (PAH) absorption of ultraviolet (UV) radiation in aquatic organisms. Early life stage aquatic organisms are predicted to be more susceptible to PAH photo-enhanced toxicity as a result of their translucence and tendency to inhabit shallow littoral or surface waters. The objective of the present study was to evaluate the sensitivity of varying ages of larval mysid shrimp (Americamysis bahia), inland silverside (Menidia beryllina), sheepshead minnow (Cyprinodon variegatus), and Gulf killifish (Fundulus grandis) to photo-enhanced toxicity and to examine the correlation between photo-enhanced toxicity and organism pigmentation. Organisms were exposed to fluoranthene and artificial UV light at different larval ages and results were compared using median lethal concentrations (LC50s) and the lethal time-to-death (LT50s). In addition, a high UV light intensity, short-duration (4-h) experiment was conducted at approximately 24 W/m(2) of ultraviolet radiation A (UV-A) and compared with a low-intensity, long-duration (12-h) experiment at approximately 8 W/m(2) of UV-A. The results indicated decreased toxicity with increasing age for all larval organisms. The amount of organism pigmentation was correlated with observed LC50 and LT50 values. High-intensity short-duration exposure resulted in greater toxicity than low-intensity long-duration UV treatments for mysid shrimp, inland silverside, and sheepshead minnow. Data from these experiments suggest that toxicity is dependent on age, pigmentation, UV light intensity, and fluoranthene concentration. © 2015 SETAC.

Enhanced Output Power of Near-Ultraviolet Light-Emitting Diodes by p-GaN Micro-Rods

NASA Astrophysics Data System (ADS)

Wang, Dong-Sheng; Zhang, Ke-Xiong; Liang, Hong-Wei; Song, Shi-Wei; Yang, De-Chao; Shen, Ren-Sheng; Liu, Yang; Xia, Xiao-Chuan; Luo, Ying-Min; Du, Guo-Tong

2014-02-01

Near-ultraviolet (UV) InGaN/AlGaN light-emitting diodes (LEDs) are grown by low-pressure metal-organic chemical vapor deposition. The scanning electronic microscope image shows that the p-GaN micro-rods are formed above the interface of p-AlGaN/p-GaN due to the rapid growth rate of p-GaN in the vertical direction. The p-GaN micro-rods greatly increase the escape probability of photons inside the LED structure. Electroluminescence intensities of the 372 nm UV LED lamps with p-GaN micro rods are 88% higher than those of the flat surface LED samples.

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

NASA Astrophysics Data System (ADS)

Engelsen, Ola; Kylling, Arve

2005-04-01

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

The MUSCLES Treasury Survey. II. Intrinsic LYα and Extreme Ultraviolet Spectra of K and M Dwarfs with Exoplanets*

NASA Astrophysics Data System (ADS)

Youngblood, Allison; France, Kevin; Loyd, R. O. Parke; Linsky, Jeffrey L.; Redfield, Seth; Schneider, P. Christian; Wood, Brian E.; Brown, Alexander; Froning, Cynthia; Miguel, Yamila; Rugheimer, Sarah; Walkowicz, Lucianne

2016-06-01

The ultraviolet (UV) spectral energy distributions (SEDs) of low-mass (K- and M-type) stars play a critical role in the heating and chemistry of exoplanet atmospheres, but are not observationally well-constrained. Direct observations of the intrinsic flux of the Lyα line (the dominant source of UV photons from low-mass stars) are challenging, as interstellar H I absorbs the entire line core for even the closest stars. To address the existing gap in empirical constraints on the UV flux of K and M dwarfs, the MUSCLES Hubble Space Telescope Treasury Survey has obtained UV observations of 11 nearby M and K dwarfs hosting exoplanets. This paper presents the Lyα and extreme-UV spectral reconstructions for the MUSCLES targets. Most targets are optically inactive, but all exhibit significant UV activity. We use a Markov Chain Monte Carlo technique to correct the observed Lyα profiles for interstellar absorption, and we employ empirical relations to compute the extreme-UV SED from the intrinsic Lyα flux in ˜100 Å bins from 100-1170 Å. The reconstructed Lyα profiles have 300 km s-1 broad cores, while >1% of the total intrinsic Lyα flux is measured in extended wings between 300 and 1200 km s-1. The Lyα surface flux positively correlates with the Mg II surface flux and negatively correlates with the stellar rotation period. Stars with larger Lyα surface flux also tend to have larger surface flux in ions formed at higher temperatures, but these correlations remain statistically insignificant in our sample of 11 stars. We also present H I column density measurements for 10 new sightlines through the local interstellar medium. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555.

Optical Technologies for UV Remote Sensing Instruments

NASA Technical Reports Server (NTRS)

Keski-Kuha, R. A. M.; Osantowski, J. F.; Leviton, D. B.; Saha, T. T.; Content, D. A.; Boucarut, R. A.; Gum, J. S.; Wright, G. A.; Fleetwood, C. M.; Madison, T. J.

1993-01-01

Over the last decade significant advances in technology have made possible development of instruments with substantially improved efficiency in the UV spectral region. In the area of optical coatings and materials, the importance of recent developments in chemical vapor deposited (CVD) silicon carbide (SiC) mirrors, SiC films, and multilayer coatings in the context of ultraviolet instrumentation design are discussed. For example, the development of chemically vapor deposited (CVD) silicon carbide (SiC) mirrors, with high ultraviolet (UV) reflectance and low scatter surfaces, provides the opportunity to extend higher spectral/spatial resolution capability into the 50-nm region. Optical coatings for normal incidence diffraction gratings are particularly important for the evolution of efficient extreme ultraviolet (EUV) spectrographs. SiC films are important for optimizing the spectrograph performance in the 90 nm spectral region. The performance evaluation of the flight optical components for the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) instrument, a spectroscopic instrument to fly aboard the Solar and Heliospheric Observatory (SOHO) mission, designed to study dynamic processes, temperatures, and densities in the plasma of the upper atmosphere of the Sun in the wavelength range from 50 nm to 160 nm, is discussed. The optical components were evaluated for imaging and scatter in the UV. The performance evaluation of SOHO/CDS (Coronal Diagnostic Spectrometer) flight gratings tested for spectral resolution and scatter in the DGEF is reviewed and preliminary results on resolution and scatter testing of Space Telescope Imaging Spectrograph (STIS) technology development diffraction gratings are presented.

Suitability of surface acoustic wave oscillators fabricated using low temperature-grown AlN films on GaN/sapphire as UV sensors.

PubMed

Chen, Tzu Chieh; Lin, Yueh Ting; Lin, Chung Yi; Chen, W C; Chen, Meei Ru; Kao, Hui-Ling; Chyi, J I; Hsu, C H

2008-02-01

Epitaxial AlN films were prepared on GaN/sapphire using a helicon sputtering system at the low temperature of 300 degrees C. Surface acoustic wave (SAW) devices fabricated on AlN/GaN/sapphire exhibited superior characteristics compared with those made on GaN/sapphire. An oscillator using an AlN/GaN/sapphirebased SAW device is presented. The oscillation frequency decreased when the device was illuminated by ultraviolet (UV) radiation, and the downshift of the oscillation frequency increased with the illuminating UV power density. The results showed that the AlN/GaN/sapphire-layered structure SAW oscillators are suitable for visible blind UV detection and opened up the feasibility of developing remote UV sensors for different ranges of wavelengths on the III-nitrides.

Bias-switchable negative and positive photoconductivity in 2D FePS3 ultraviolet photodetectors.

PubMed

Gao, Yi; Lei, Shuijin; Kang, Tingting; Fei, Linfeng; Mak, Chee-Leung; Yuan, Jian; Zhang, Mingguang; Li, Shaojuan; Bao, Qiaoliang; Zeng, Zhongming; Wang, Zhao; Gu, Haoshuang; Zhang, Kai

2018-06-15

Metal-phosphorus-trichalcogenides (MPTs), represented by NiPS 3 , FePS 3 , etc, are newly developed 2D wide-bandgap semiconductors and have been proposed as excellent candidates for ultraviolet (UV) optoelectronics. In spite of having superior advantages for solar-blind UV photodetectors, including those free of surface trap states, being highly compatible with versatile integrations as well as having an appropriate band gap, to date relevant study is rare. In this work, the photoresponse characteristic of UV detectors based on few-layer FePS 3 has been comprehensively investigated. The responsivity of the photodetector, which is observed to be determined by bias gate voltage, may achieve as high as 171.6 mAW -1 under the illumination of 254 nm weak light, which is comparable to most commercial UV detectors. Notably, both negative and positive photoconductivities exist in the FePS 3 photodetectors and can be controllably switched with bias voltage. The eminent and novel photoresponse property paves the way for the further development and practical use of 2D MPTs in high-performance UV photodetections.

Bias-switchable negative and positive photoconductivity in 2D FePS3 ultraviolet photodetectors

NASA Astrophysics Data System (ADS)

Gao, Yi; Lei, Shuijin; Kang, Tingting; Fei, Linfeng; Mak, Chee-Leung; Yuan, Jian; Zhang, Mingguang; Li, Shaojuan; Bao, Qiaoliang; Zeng, Zhongming; Wang, Zhao; Gu, Haoshuang; Zhang, Kai

2018-06-01

Metal-phosphorus-trichalcogenides (MPTs), represented by NiPS3, FePS3, etc, are newly developed 2D wide-bandgap semiconductors and have been proposed as excellent candidates for ultraviolet (UV) optoelectronics. In spite of having superior advantages for solar-blind UV photodetectors, including those free of surface trap states, being highly compatible with versatile integrations as well as having an appropriate band gap, to date relevant study is rare. In this work, the photoresponse characteristic of UV detectors based on few-layer FePS3 has been comprehensively investigated. The responsivity of the photodetector, which is observed to be determined by bias gate voltage, may achieve as high as 171.6 mAW‑1 under the illumination of 254 nm weak light, which is comparable to most commercial UV detectors. Notably, both negative and positive photoconductivities exist in the FePS3 photodetectors and can be controllably switched with bias voltage. The eminent and novel photoresponse property paves the way for the further development and practical use of 2D MPTs in high-performance UV photodetections.

Ultraviolet Raman Wide-Field Hyperspectral Imaging Spectrometer for Standoff Trace Explosive Detection.

PubMed

Hufziger, Kyle T; Bykov, Sergei V; Asher, Sanford A

2017-02-01

We constructed the first deep ultraviolet (UV) Raman standoff wide-field imaging spectrometer. Our novel deep UV imaging spectrometer utilizes a photonic crystal to select Raman spectral regions for detection. The photonic crystal is composed of highly charged, monodisperse 35.5 ± 2.9 nm silica nanoparticles that self-assemble in solution to produce a face centered cubic crystalline colloidal array that Bragg diffracts a narrow ∼1.0 nm full width at half-maximum (FWHM) UV spectral region. We utilize this photonic crystal to select and image two different spectral regions containing resonance Raman bands of pentaerythritol tetranitrate (PETN) and NH 4 NO 3 (AN). These two deep UV Raman spectral regions diffracted were selected by angle tuning the photonic crystal. We utilized this imaging spectrometer to measure 229 nm excited UV Raman images containing ∼10-1000 µg/cm 2 samples of solid PETN and AN on aluminum surfaces at 2.3 m standoff distances. We estimate detection limits of ∼1 µg/cm 2 for PETN and AN films under these experimental conditions.

Ultraviolet A irradiation of the eye activates a nitric oxide-dependent hypothalamo-pituitary pro-opiomelanocortin pathway and modulates the functions of Langerhans cells.

PubMed

Hiramoto, Keiichi

2009-06-01

Ultraviolet A (UV-A) radiation decreases Langerhans cells (LC) in the skin specifically at the site of exposure. Unexpectedly, UV-A irradiation of the eye has been found systemically downregulating epidermal LC in mice. Male C57BL/6j mice and an inducible type of nitric oxide synthase knockout mice (iNOS(-/-)) were used in this study. The eye or ear was locally exposed to UV-A after covering the remaining body surface with aluminum foil at a dose of 110 kJ/m(2) using a sunlamp. Localized UV-A irradiation of the eye downregulated epidermal LC. The hypophysectomy strongly inhibited the UV-A-induced downregulation of LC. To elucidate the pathway by UV-A irradiation of the eye, the effect of a bilateral ciliary ganglionectomy and denervation of the optic nerves was examined. Optic nerve denervation strongly inhibited LC downregulation in response to localized irradiation of the eye. Furthermore, no LC downregulation in response to localized UV-A irradiation of the eye was observed in iNOS(-/-) mice. These results clearly indicate that a signal evoked by UV-A irradiation of the eye is transmitted in a nitric oxide-dependent manner through the optic nerves to the hypothalamo-pituitary pro-opiomelanocortin system.

The Ultraviolet Spectrograph on the Europa Mission (Europa-UVS)

NASA Astrophysics Data System (ADS)

Retherford, K. D.; Gladstone, R.; Greathouse, T. K.; Steffl, A.; Davis, M. W.; Feldman, P. D.; McGrath, M. A.; Roth, L.; Saur, J.; Spencer, J. R.; Stern, S. A.; Pope, S.; Freeman, M. A.; Persyn, S. C.; Araujo, M. F.; Cortinas, S. C.; Monreal, R. M.; Persson, K. B.; Trantham, B. J.; Versteeg, M. H.; Walther, B. C.

2015-12-01

NASA's Europa multi-flyby mission is designed to provide a diversity of measurements suited to enrich our understanding of the potential habitability of this intriguing ocean world. The Europa mission's Ultraviolet Spectrograph, Europa-UVS, is the sixth in a series of successful ultraviolet imaging spectrographs (Rosetta-Alice, New Horizons Pluto-Alice, LRO-LAMP) and, like JUICE-UVS (now under Phase B development), is largely based on the most recent of these to fly, Juno-UVS. Europa-UVS observes photons in the 55-210 nm wavelength range, at moderate spectral and spatial resolution along a 7.5° slit. Three distinct apertures send light to the off-axis telescope mirror feeding the long-slit spectrograph: i) a main entrance airglow port is used for most observations (e.g., airglow, aurora, surface mapping, and stellar occultations); ii) a high-spatial-resolution port consists of a small hole in an additional aperture door, and is used for detailed observations of bright targets; and iii) a separate solar port allows for solar occultations, viewing at a 60° offset from the nominal payload boresight. Photon event time-tagging (pixel list mode) and programmable spectral imaging (histogram mode) allow for observational flexibility and optimal science data management. As on Juno-UVS, the effects of penetrating electron radiation on electronic parts and data quality are mitigated through contiguous shielding, filtering of pulse height amplitudes, management of high-voltage settings, and careful use of radiation-hard parts. The science goals of Europa-UVS are to: 1) Determine the composition & chemistry, source & sinks, and structure & variability of Europa's atmosphere, from equator to pole; 2) Search for and characterize active plumes in terms of global distribution, structure, composition, and variability; 3) Explore the surface composition & microphysics and their relation to endogenic & exogenic processes; and 4) Investigate how energy and mass flow in the Europa atmosphere, neutral cloud & plasma torus, and footprint on Jupiter. Here we present the UVS investigation by describing the science we plan to address, the salient details of the instrument, and the basic concept of operations.

Development of colour and firmness in strawberry crops is UV light sensitive, but colour is not a good predictor of several quality parameters.

PubMed

Ordidge, Matthew; García-Macías, Paulina; Battey, Nicholas H; Gordon, Michael H; John, Philip; Lovegrove, Julie A; Vysini, Eleni; Wagstaffe, Alexandra; Hadley, Paul

2012-06-01

Strawberry (Fragaria × ananassa Duchesne var. Elsanta) plants were grown in polytunnels covered with three polythene films that transmitted varying levels of ultraviolet (UV) light. Fruit were harvested under near-commercial conditions and quality and yield were measured. During ripening, changes in the colour parameters of individual fruit were monitored, and the accuracy of using surface colour to predict other quality parameters was determined by analysing the correlation between colour and quality parameters within UV treatments. Higher exposure to UV during growth resulted in the fruit becoming darker at harvest and developing surface colour more quickly; fruit were also firmer at harvest, but shelf life was not consistently affected by the UV regime. Surface colour measurements were poorly correlated to firmness, shelf life or total phenolics, anthocyanins and ellagic acid contents. Although surface colour of strawberry fruits was affected by the UV regime during growth, and this parameter is an important factor in consumer perception, we concluded that the surface colour at the time of harvest was, contrary to consumer expectations, a poor indicator of firmness, potential shelf life or anthocyanin content. Copyright © 2011 Society of Chemical Industry.

The TROPOMI surface UV algorithm

NASA Astrophysics Data System (ADS)

Lindfors, Anders V.; Kujanpää, Jukka; Kalakoski, Niilo; Heikkilä, Anu; Lakkala, Kaisa; Mielonen, Tero; Sneep, Maarten; Krotkov, Nickolay A.; Arola, Antti; Tamminen, Johanna

2018-02-01

The TROPOspheric Monitoring Instrument (TROPOMI) is the only payload of the Sentinel-5 Precursor (S5P), which is a polar-orbiting satellite mission of the European Space Agency (ESA). TROPOMI is a nadir-viewing spectrometer measuring in the ultraviolet, visible, near-infrared, and the shortwave infrared that provides near-global daily coverage. Among other things, TROPOMI measurements will be used for calculating the UV radiation reaching the Earth's surface. Thus, the TROPOMI surface UV product will contribute to the monitoring of UV radiation by providing daily information on the prevailing UV conditions over the globe. The TROPOMI UV algorithm builds on the heritage of the Ozone Monitoring Instrument (OMI) and the Satellite Application Facility for Atmospheric Composition and UV Radiation (AC SAF) algorithms. This paper provides a description of the algorithm that will be used for estimating surface UV radiation from TROPOMI observations. The TROPOMI surface UV product includes the following UV quantities: the UV irradiance at 305, 310, 324, and 380 nm; the erythemally weighted UV; and the vitamin-D weighted UV. Each of these are available as (i) daily dose or daily accumulated irradiance, (ii) overpass dose rate or irradiance, and (iii) local noon dose rate or irradiance. In addition, all quantities are available corresponding to actual cloud conditions and as clear-sky values, which otherwise correspond to the same conditions but assume a cloud-free atmosphere. This yields 36 UV parameters altogether. The TROPOMI UV algorithm has been tested using input based on OMI and the Global Ozone Monitoring Experiment-2 (GOME-2) satellite measurements. These preliminary results indicate that the algorithm is functioning according to expectations.

UIT Observations of Early-Type Galaxies and Analysis of the FUSE Spectrum of a Subdwarf B Star

NASA Technical Reports Server (NTRS)

Ohl, Raymond G.; Krebs, Carolyn (Technical Monitor)

2001-01-01

This work covers Ultraviolet Imaging Telescope (UIT) observations of early-type galaxies (155 nm) and Far Ultraviolet Spectroscopic Explorer (FUSE) spectra of a Galactic subdwarf B star (sdB). Early UV space astronomy missions revealed that early-type galaxies harbor a population of stars with effective temperatures greater than that of the main sequence turn-off (about 6,000 K) and UV emission that is very sensitive to characteristics of the stellar population. We present UV (155 nm) surface photometry and UV-B color profiles for 8 E and SO galaxies observed by UIT. Some objects have de Vaucouleurs surface brightness profiles, while others have disk-like profiles, but we find no other evidence for the presence of a disk or young, massive stars. There is a wide range of UV-B color gradients, but there is no correlation with metallicity gradients. SdB stars are the leading candidate UV emitters in old, high metallicity stellar populations (e.g., early-type galaxies). We observed the Galactic sdB star PG0749+658 with FUSE and derived abundances with the aim of constraining models of the heavy element distribution in sdB atmospheres. All of the elements measured are depleted with respect to solar, except for Cr and Mn, which are about solar, and Ni, which is enhanced. This work was supported in part by NASA grants NAG5-700 and NAG5-6403 to the University of Virginia and NAS5-32985 to Johns Hopkins University.

Enhancements in biologically effective ultraviolet radiation following volcanic eruptions

NASA Technical Reports Server (NTRS)

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

1992-01-01

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

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

NASA Astrophysics Data System (ADS)

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

2010-03-01

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

Surface Modified TiO2 Obscurants for Increased Safety and Performance

DTIC Science & Technology

2012-11-01

based obscurant devices in performance. 15. SUBJECT TERMS Obscurant, visible, IR , smoke, TiO2, aerosol, particle, surface modification...hexamethyldimethoxysilane IR Infrared wavelength LabRAM Lab scale Resonant Acoustic Mixer from Resodyn Corporation LPM Liters Per Minute M106 Currently fielded (Army...trinitrophloroglucinol UV-Vis Ultraviolet-visible wavelengths KEYWORDS Obscurant, visible, IR , smoke, TiO2, aerosol, particle, surface modification

Ultraviolet safety assessments of insect light traps

PubMed Central

Sliney, David H.; Gilbert, David W.; Lyon, Terry

2016-01-01

ABSTRACT Near-ultraviolet (UV-A: 315–400 nm), “black-light,” electric lamps were invented in 1935 and ultraviolet insect light traps (ILTs) were introduced for use in agriculture around that time. Today ILTs are used indoors in several industries and in food-service as well as in outdoor settings. With recent interest in photobiological lamp safety, safety standards are being developed to test for potentially hazardous ultraviolet emissions. A variety of UV “Black-light” ILTs were measured at a range of distances to assess potential exposures. Realistic time-weighted human exposures are shown to be well below current guidelines for human exposure to ultraviolet radiation. These UV-A exposures would be far less than the typical UV-A exposure in the outdoor environment. Proposals are made for realistic ultraviolet safety standards for ILT products. PMID:27043058

Giardia duodenalis: Number and Fluorescence Reduction Caused by the Advanced Oxidation Process (H2O2/UV)

PubMed Central

Guimarães, José Roberto; Franco, Regina Maura Bueno; Guadagnini, Regiane Aparecida; dos Santos, Luciana Urbano

2014-01-01

This study evaluated the effect of peroxidation assisted by ultraviolet radiation (H2O2/UV), which is an advanced oxidation process (AOP), on Giardia duodenalis cysts. The cysts were inoculated in synthetic and surface water using a concentration of 12 g H2O2 L−1 and a UV dose (λ = 254 nm) of 5,480 mJcm−2. The aqueous solutions were concentrated using membrane filtration, and the organisms were observed using a direct immunofluorescence assay (IFA). The AOP was effective in reducing the number of G. duodenalis cysts in synthetic and surface water and was most effective in reducing the fluorescence of the cyst walls that were present in the surface water. The AOP showed a higher deleterious potential for G. duodenalis cysts than either peroxidation (H2O2) or photolysis (UV) processes alone. PMID:27379301

Influence of hydrophilic pre-treatment on resin bonding to zirconia ceramics.

PubMed

Noro, Akio; Kameyama, Atsushi; Haruyama, Akiko; Takahashi, Toshiyuki

2015-01-01

Atmospheric plasma or ultraviolet (UV) treatment alters the surface characteristics of tetragonal zirconia polycrystal (TZP), increasing its hydrophilicity by reducing the contact angle against water to zero. This suggests that such treatment would increase the wettability of bonding resin. The purpose of this study was to determine how increasing the hydrophilicity of TZP through plasma irradiation, UV treatment, or application of ceramic primer affected initial bonding with resin composites. Here, the effect of each pre-treatment on the hydrophilicity of TZP surfaces was determined by evaluating change in shear bond strength. Plasma irradiation, UV, or ceramic primer pre-treatment showed no significant effect on bonding strength between TZP surfaces and resin composites. In addition, alumina blasting yielded no significant increase in bond strength. Plasma irradiation, UV treatment, or ceramic primer pre-treatment did not lead to significant increase in bond strength between TZP and resin composites.

Photochromic cross-link polymer for color changing and sensing surface

NASA Astrophysics Data System (ADS)

Fu, Richard; Shi, Jianmin; Forsythe, Eric; Srour, Merric

2016-12-01

Photochromic cross-link polymers were developed using patented ultraviolet (UV) photoinitiator and commercial photochromic dyes. The photochromic dyes have been characterized by measuring absorbance before and after UV activation using UV-visible (Vis) spectrometry with varying activation intensities and wavelengths. Photochromic cross-link polymers were characterized by a dynamic xenon and UV light activation and fading system. The curing processes on cloth were established and tested to obtain effective photochromic responses. Both PulseForge photonic curing and PulseForge plus heat surface curing processes had much better photochromic responses (18% to 19%, 16% to 25%, respectively) than the xenon lamp treatment (8%). The newly developed photochromic cross-link polymer showed remarkable coloration contrasts and fast and comparable coloration and fading rates. Those intelligent, controlled color changing and sensing capabilities will be used on flexible and "drapeable" surfaces, which will incorporate ultra-low power sensors, sensor indicators, and identifiers.

Interface Properties of Atomic-Layer-Deposited Al2O3 Thin Films on Ultraviolet/Ozone-Treated Multilayer MoS2 Crystals.

PubMed

Park, Seonyoung; Kim, Seong Yeoul; Choi, Yura; Kim, Myungjun; Shin, Hyunjung; Kim, Jiyoung; Choi, Woong

2016-05-11

We report the interface properties of atomic-layer-deposited Al2O3 thin films on ultraviolet/ozone (UV/O3)-treated multilayer MoS2 crystals. The formation of S-O bonds on MoS2 after low-power UV/O3 treatment increased the surface energy, allowing the subsequent deposition of uniform Al2O3 thin films. The capacitance-voltage measurement of Au-Al2O3-MoS2 metal oxide semiconductor capacitors indicated n-type MoS2 with an electron density of ∼10(17) cm(-3) and a minimum interface trap density of ∼10(11) cm(-2) eV(-1). These results demonstrate the possibility of forming a high-quality Al2O3-MoS2 interface by proper UV/O3 treatment, providing important implications for their integration into field-effect transistors.

Surface plasmon coupling for suppressing p-GaN absorption and TM-polarized emission in a deep-UV light-emitting diode.

PubMed

Kuo, Yang; Su, Chia-Ying; Hsieh, Chieh; Chang, Wen-Yen; Huang, Chu-An; Kiang, Yean-Woei; Yang, C C

2015-09-15

The radiated power enhancement (suppression) of an in- (out-of-) plane-oriented radiating dipole at a desired emission wavelength in the deep-ultraviolet (UV) range when it is coupled with a surface plasmon (SP) resonance mode induced on a nearby Al nanoparticle (NP) is demonstrated. Also, it is found that the enhanced radiated power propagates mainly in the direction from the Al NP toward the dipole. Such SP coupling behaviors can be used for suppressing the transverse-magnetic (TM)-polarized emission, enhancing the transverse-electric-polarized emission, and reducing the UV absorption of the p-GaN layer in an AlGaN-based deep-UV light-emitting diode by embedding a sphere-like Al NP in its p-AlGaN layer.

DATA FROM A SOLAR ULTRAVIOLET MONITORING NETWORK

EPA Science Inventory

The U.S. Environmental Protection Agency, in conjunction with the National Park Service, operates a network of 21 spectrophotometers, measuring spectrally-resolved, surface UV radiation of wavelengths 290-363 nanometers. Fourteen of the measurement sites are in National Parks,...

Degradation of modified carbon black/epoxy nanocomposite coatings under ultraviolet exposure

NASA Astrophysics Data System (ADS)

Ghasemi-Kahrizsangi, Ahmad; Shariatpanahi, Homeira; Neshati, Jaber; Akbarinezhad, Esmaeil

2015-10-01

Degradation of epoxy coatings with and without Carbon Black (CB) nanoparticles under ultraviolet (UV) radiation were investigated using electrochemical impedance spectroscopy (EIS). Sodium dodecyl sulfate (SDS) was used to obtain a good dispersion of CB nanoparticles in a polymer matrix. TEM analysis proved a uniform dispersion of modified CB nanoparticles in epoxy coating. The coatings were subjected to UV radiation to study the degradation behavior and then immersed in 3.5 wt% NaCl. The results showed that the electrochemical behavior of neat epoxy coating was related to the formation and development of microcracks on the surface. The occurrence of microcracks on the surface of the coatings and consequently the penetration of ionic species reduced by adding CB nanoparticles into the formulation of the coatings. CB nanoparticles decreased degradation of CB coatings by absorbing UV irradiation. The ATR-FTIR results showed that decrease in the intensity of methyl group as main peak in presence of 2.5 wt% CB was lower than neat epoxy. In addition, the reduction in impedance of neat epoxy coating under corrosive environment was larger than CB coatings. The CB coating with 2.5 wt% nanoparticles had the highest impedance to corrosive media after 2000 h UV irradiation and 24 h immersion in 3.5 wt% NaCl.

Ultraviolet light treatment for the restoration of age-related degradation of titanium bioactivity.

PubMed

Hori, Norio; Ueno, Takeshi; Suzuki, Takeo; Yamada, Masahiro; Att, Wael; Okada, Shunsaku; Ohno, Akinori; Aita, Hideki; Kimoto, Katsuhiko; Ogawa, Takahiro

2010-01-01

To examine the bioactivity of differently aged titanium (Ti) disks and to determine whether ultraviolet (UV) light treatment reverses the possible adverse effects of Ti aging. Ti disks with three different surface topographies were prepared: machined, acid-etched, and sandblasted. The disks were divided into three groups: disks tested for biologic capacity immediately after processing (fresh surfaces), disks stored under dark ambient conditions for 4 weeks, and disks stored for 4 weeks and treated with UV light. The protein adsorption capacity of Ti was examined using albumin and fibronectin. Cell attraction to Ti was evaluated by examining migration, attachment, and spreading behaviors of human osteoblasts on Ti disks. Osteoblast differentiation was evaluated by examining alkaline phosphatase activity, the expression of bone-related genes, and mineralized nodule area in the culture. Four-week-old Ti disks showed = or < 50% protein adsorption after 6 hours of incubation compared with fresh disks, regardless of surface topography. Total protein adsorption for 4-week-old surfaces did not reach the level of fresh surfaces, even after 24 hours of incubation. Fifty percent fewer human osteoblasts migrated and attached to 4-week-old surfaces compared with fresh surfaces. Alkaline phosphatase activity, gene expression, and mineralized nodule area were substantially reduced on the 4-week-old surfaces. The reduction of these biologic parameters was associated with the conversion of Ti disks from superhydrophilicity to hydrophobicity during storage for 4 weeks. UV-treated 4-week-old disks showed even higher protein adsorption, osteoblast migration, attachment, differentiation, and mineralization than fresh surfaces, and were associated with regenerated superhydrophilicity. Time-related degradation of Ti bioactivity is substantial and impairs the recruitment and function of human osteoblasts as compared to freshly prepared Ti surfaces, suggesting a "biologic aging"-like change of Ti. UV treatment of aged Ti, however, restores and even enhances bioactivity, exceeding its innate levels.

The shady side of solar protection.

PubMed

Parsons, P G; Neale, R; Wolski, P; Green, A

1998-04-06

To determine the value of shade in protecting humans from solar ultraviolet (UV) radiation. Measurement with photometers of protection factors for ultraviolet B radiation (UVB) and for total solar radiation for different types of trees and other structures during the summer months (1995-1997) in south-east Queensland. (The protection ratio is the ratio of the intensity of UVB or total solar radiation in direct sunlight to that in shade.) For summer sun at midday, the mean (SD) UV protection ratio for the shade of trees (n = 65) was 4.21 (1.36) on a horizontal surface and 1.33 (0.30) on a vertical surface. In contrast, the mean (SD) protection ratio for total solar energy (primarily infrared) was much higher (12.1 [1.4]). Trees common in recreational areas in Australia (eucalypts: UV protection ratio, 3.52 [0.79]; Norfolk Island pines: UV protection ratio, 3.72 [0.98]) offered reduced protection compared with trees with more dense foliage (UV protection ratio, 5.48 [1.44]). Over a whole day, measurement of shade by trees and other structures showed that the UV protection ratio was lower in the morning and afternoon. Shade from awnings, buildings and hats gave similar results to those for trees. Both at midday and over a whole day satisfactory protection (UV protection ratio > 15) was obtained only in shade which eliminated exposure to the sky as well as to direct sunlight; for example, in thickly wooded areas and under low, widely overhanging structures. Most forms of shade, while useful, offer people insufficient protection from solar UV. A fair-skinned person sheltering under a tree could suffer sunburn after less than one hour. There is a need for appropriate design of structural shade, use of other solar protection measures in conjunction with shade, and research on behavioural responses to shade.

Degradation of polycyclic aromatic hydrocarbons in a coking wastewater treatment plant residual by an O3/ultraviolet fluidized bed reactor.

PubMed

Lin, Chong; Zhang, Wanhui; Yuan, Mengyang; Feng, Chunhua; Ren, Yuan; Wei, Chaohai

2014-09-01

Coking wastewater treatment plant (CWWTP) represents a typical point source of polycyclic aromatic hydrocarbons (PAHs) to the water environment and threatens the safety of drinking water in downstream regions. To enhance the removal of residual PAHs from bio-treated coking wastewater, a pilot-scale O3/ultraviolet (UV) fluidized bed reactor (O3/UV FBR) was designed and different operating factors including UV irradiation intensity, pH, initial concentration, contact time, and hydraulic retention time (HRT) were investigated at an ozone level of 240 g h(-1) and 25 ± 3 °C. A health risk evaluation and cost analysis were also carried out under the continuous-flow mode. As far as we know, this is the first time an O3/UV FBR has been explored for PAHs treatment. The results indicated that between 41 and 75 % of 18 target PAHs were removed in O3/UV FBR due to synergistic effects of UV irradiation. Both increased reaction time and increased pH were beneficial for the removal of PAHs. The degradation of the target PAHs within 8 h can be well fitted by the pseudo-first-order kinetics (R (2) > 0.920). The reaction rate was also positively correlated with the initial concentrations of PAHs. The health risk assessment showed that the total amount of carcinogenic substance exposure to surface water was reduced by 0.432 g day(-1). The economic analysis showed that the O3/UV FBR was able to remove 18 target PAHs at a cost of US$0.34 m(-3). These results suggest that O3/UV FBR is efficient in removing residuals from CWWTP, thus reducing the accumulation of persistent pollutant released to surface water.

Ultraviolet-radiation-induced inflammation promotes angiotropism and metastasis in melanoma

NASA Astrophysics Data System (ADS)

Bald, Tobias; Quast, Thomas; Landsberg, Jennifer; Rogava, Meri; Glodde, Nicole; Lopez-Ramos, Dorys; Kohlmeyer, Judith; Riesenberg, Stefanie; van den Boorn-Konijnenberg, Debby; Hömig-Hölzel, Cornelia; Reuten, Raphael; Schadow, Benjamin; Weighardt, Heike; Wenzel, Daniela; Helfrich, Iris; Schadendorf, Dirk; Bloch, Wilhelm; Bianchi, Marco E.; Lugassy, Claire; Barnhill, Raymond L.; Koch, Manuel; Fleischmann, Bernd K.; Förster, Irmgard; Kastenmüller, Wolfgang; Kolanus, Waldemar; Hölzel, Michael; Gaffal, Evelyn; Tüting, Thomas

2014-03-01

Intermittent intense ultraviolet (UV) exposure represents an important aetiological factor in the development of malignant melanoma. The ability of UV radiation to cause tumour-initiating DNA mutations in melanocytes is now firmly established, but how the microenvironmental effects of UV radiation influence melanoma pathogenesis is not fully understood. Here we report that repetitive UV exposure of primary cutaneous melanomas in a genetically engineered mouse model promotes metastatic progression, independent of its tumour-initiating effects. UV irradiation enhanced the expansion of tumour cells along abluminal blood vessel surfaces and increased the number of lung metastases. This effect depended on the recruitment and activation of neutrophils, initiated by the release of high mobility group box 1 (HMGB1) from UV-damaged epidermal keratinocytes and driven by Toll-like receptor 4 (TLR4). The UV-induced neutrophilic inflammatory response stimulated angiogenesis and promoted the ability of melanoma cells to migrate towards endothelial cells and use selective motility cues on their surfaces. Our results not only reveal how UV irradiation of epidermal keratinocytes is sensed by the innate immune system, but also show that the resulting inflammatory response catalyses reciprocal melanoma-endothelial cell interactions leading to perivascular invasion, a phenomenon originally described as angiotropism in human melanomas by histopathologists. Angiotropism represents a hitherto underappreciated mechanism of metastasis that also increases the likelihood of intravasation and haematogenous dissemination. Consistent with our findings, ulcerated primary human melanomas with abundant neutrophils and reactive angiogenesis frequently show angiotropism and a high risk for metastases. Our work indicates that targeting the inflammation-induced phenotypic plasticity of melanoma cells and their association with endothelial cells represent rational strategies to specifically interfere with metastatic progression.

Ultraviolet resources over Northern Eurasia.

PubMed

Chubarova, Natalia; Zhdanova, Yekaterina

2013-10-05

We propose a new climatology of UV resources over Northern Eurasia, which includes the assessments of both detrimental (erythema) and positive (vitamin D synthesis) effects of ultraviolet radiation on human health. The UV resources are defined by using several classes and subclasses - UV deficiency, UV optimum, and UV excess - for 6 different skin types. To better quantifying the vitamin D irradiance threshold we accounted for an open body fraction S as a function of effective air temperature. The spatial and temporal distribution of UV resources was estimated by radiative transfer (RT) modeling (8 stream DISORT RT code) with 1×1° grid and monthly resolution. For this purpose special datasets of main input geophysical parameters (total ozone content, aerosol characteristics, surface UV albedo, UV cloud modification factor) have been created over the territory of Northern Eurasia. The new approaches were used to retrieve aerosol parameters and cloud modification factor in the UV spectral region. As a result, the UV resources were obtained for clear-sky and mean cloudy conditions for different skin types. We show that the distribution of UV deficiency, UV optimum and UV excess is regulated by various geophysical parameters (mainly, total ozone, cloudiness and open body fraction) and can significantly deviate from latitudinal dependence. We also show that the UV optimum conditions can be simultaneously observed for people with different skin types (for example, for 4-5 skin types at the same time in spring over Western Europe). These UV optimum conditions for different skin types occupy a much larger territory over Europe than that over Asia. Copyright © 2013 Elsevier B.V. All rights reserved.

Ultraviolet Communication for Medical Applications

DTIC Science & Technology

2015-06-01

DEI procured several UVC phosphors and tested them with vacuum UV (VUV) excitation. Available emission peaks include: 226 nm, 230 nm, 234 nm, 242...SUPPLEMENTARY NOTES Report contains color. 14. ABSTRACT Under this Phase II SBIR effort, Directed Energy Inc.’s (DEI) proprietary ultraviolet ( UV ...15. SUBJECT TERMS Non-line-of-sight (NLOS), networking, optical communication, plasma-shells, short range, ultraviolet ( UV ) light 16. SECURITY

Ultraviolet radiation, human health, and the urban forest

Treesearch

Gordon M. Heisler; Richard H. Grant

2000-01-01

Excess exposure to ultraviolet (UV) radiation from the sun, particularly the ultraviolet B (UVB) portion, has been linked with adverse effects on human health ranging from skin cancers to eye diseases such as cataracts. Trees may prevent even greater disease rates in humans by reducing UV exposure. Tree shade greatly reduces UV irradiance when both the sun and sky are...

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

NASA Technical Reports Server (NTRS)

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

2011-01-01

Ultraviolet (UV) light has long been used in terrestrial water treatment systems for photodisinfection and the removal of organic compounds by several processes including photoadsorption, photolysis, and photocatalytic oxidation/reduction. Despite its effectiveness for water treatment, UV has not been explored for spacecraft applications because of concerns about the safety and reliability of mercury-containing UV lamps. However, recent advances in ultraviolet light emitting diodes (UV LEDs) have enabled the utilization of nanomaterials that possess the appropriate optical properties for the manufacture of LEDs capable of producing monochromatic light at germicidal wavelengths. This report describes the testing of a commercial-off-the-shelf, high power Nichia UV-A LED (250mW A365nnJ for the excitation of titanium dioxide as a point-of-use (POD) disinfection device in a potable water system. The combination of an immobilized, high surface area photocatalyst with a UV-A LED is promising for potable water system disinfection since toxic chemicals and resupply requirements are reduced. No additional consumables like chemical biocides, absorption columns, or filters are required to disinfect and/or remove potentially toxic disinfectants from the potable water prior to use. Experiments were conducted in a static test stand consisting of a polypropylene microtiter plate containing 3mm glass balls coated with titanium dioxide. Wells filled with water were exposed to ultraviolet light from an actively-cooled UV-A LED positioned above each well and inoculated with six individual challenge microorganisms recovered from the International Space Station (ISS): Burkholderia cepacia, Cupriavidus metallidurans, Methylobacterium fujisawaense, Pseudomonas aeruginosa, Sphingomonas paucimobilis and Wautersia basilensis. Exposure to the Nichia UV-A LED with photocatalytic oxidation resulted in a complete (>7-log) reduction of each challenge bacteria population in <180 minutes of contact time. With continued advances in the design and manufacture of UV-A LEDs and semi-conducting photocatalysts, LED activated photochemical process technology promises to extend its application to spacecraft environmental systems.

Performance Results from In-Flight Commissioning of the Juno Ultraviolet Spectrograph (Juno-UVS)

NASA Astrophysics Data System (ADS)

Greathouse, Thomas K.; Gladstone, G. R.; Davis, M. W.; Slater, D. C.; Versteeg, M. H.; Persson, K. B.; Winters, G. S.; Persyn, S. C.; Eterno, J. S.

2012-10-01

We present a description of the Juno ultraviolet spectrograph (Juno-UVS), results from the successful in-flight commissioning performed between December 5th and 13th 2011, and some predictions of future Jupiter observations. Juno-UVS is a modest power (9.0 W) ultraviolet spectrograph based on the Alice instruments now in flight aboard the European Space Agency’s Rosetta spacecraft, NASA’s New Horizons spacecraft, and the LAMP instrument aboard NASA’s Lunar Reconnaissance Orbiter. However, unlike the other Alice spectrographs, Juno-UVS sits aboard a rotationally stabilized spacecraft. The planned 2 rpm rotation rate for the primary mission results in integration times per spatial resolution element per spin of only 17 ms. Thus, data was retrieved from many spins and then remapped and co-added to build up integration times on bright stars to measure the effective area, spatial resolution, map out scan mirror pointing positions, etc. The Juno-UVS scan mirror allows for pointing of the slit approximately ±30° from the spacecraft spin plane. This ability gives Juno-UVS access to half the sky at any given spacecraft orientation. We will describe our process for solving for the pointing of the scan mirror relative to the Juno spacecraft and present our initial half sky survey of UV bright stars complete with constellation overlays. The primary job of Juno-UVS will be to characterize Jupiter’s UV auroral emissions and relate them to in situ particle measurements. The ability to point the slit will facilitate these measurements, allowing Juno-UVS to observe the surface positions of magnetic field lines Juno is flying through giving a direct connection between the particle measurements on the spacecraft to the observed reaction of Jupiter’s atmosphere to those particles. Finally, we will describe planned observations to be made during Earth flyby in October 2013 that will complete the in-flight characterization.

Reactor for simulation and acceleration of solar ultraviolet damage

NASA Technical Reports Server (NTRS)

Laue, E.; Gupta, A.

1979-01-01

An environmental test chamber providing acceleration of UV radiation and precise temperature control (+ or -)1 C was designed, constructed and tested. This chamber allows acceleration of solar ultraviolet up to 30 suns while maintaining temperature of the absorbing surface at 30 C - 60 C. This test chamber utilizes a filtered medium pressure mercury arc as the source of radiation, and a combination of selenium radiometer and silicon radiometer to monitor solar ultraviolet (295-340 nm) and total radiant power output, respectively. Details of design and construction and operational procedures are presented along with typical test data.

Development of UV-curable liquid for in-liquid fluorescence alignment in ultraviolet nanoimprint lithography

NASA Astrophysics Data System (ADS)

Ochiai, Kento; Kikuchi, Eri; Ishito, Yota; Kumagai, Mari; Nakamura, Takahiro; Nakagawa, Masaru

2018-06-01

We studied a fluorescent UV-curable resin suitable for fluorescence alignment in UV nanoimprinting. The addition of a cationic fluorescent dye caused radical photopolymerization of a UV-curable resin by exposure to visible excitation light for fluorescence microscope observation. The microscope observation of a resin film prepared by pressing resin droplets on a silica substrate with a fluorinated silica superstrate revealed that the cationic dye molecules were preferably adsorbed onto the silica surface. It was indicated that the dye molecules concentrated on the silica surface may cause the photocuring. A nonionic fluorescent dye was selected owing to its low polar symmetrical structure and its solubility parameter close to monomers. The fluorescent UV-curable resin with the nonionic dye showed uncured stability to exposure to visible excitation light for 30 min with a light intensity of 8.5 mW cm‑2 detected at 530 nm.

UV irradiance and albedo at Union Glacier Camp (Antarctica): a case study.

PubMed

Cordero, Raul R; Damiani, Alessandro; Ferrer, Jorge; Jorquera, Jose; Tobar, Mario; Labbe, Fernando; Carrasco, Jorge; Laroze, David

2014-01-01

We report on the first spectral measurements of ultraviolet (UV) irradiance and the albedo at a Camp located in the southern Ellsworth Mountains on the broad expanse of Union Glacier (700 m altitude, 79° 46' S; 82° 52'W); about 1,000 km from the South Pole. The measurements were carried out by using a double monochromator-based spectroradiometer during a campaign (in December 2012) meant to weight up the effect of the local albedo on the UV irradiance. We found that the albedo measured at noon was about 0.95 in the UV and the visible part of the spectrum. This high surface reflectivity led to enhancements in the UV index under cloudless conditions of about 50% in comparison with snow free surfaces. Spectral measurements carried out elsewhere as well as estimates retrieved from the Ozone Monitoring Instrument (OMI) were used for further comparisons.

UV Irradiance and Albedo at Union Glacier Camp (Antarctica): A Case Study

PubMed Central

Cordero, Raul R.; Damiani, Alessandro; Ferrer, Jorge; Jorquera, Jose; Tobar, Mario; Labbe, Fernando; Carrasco, Jorge; Laroze, David

2014-01-01

We report on the first spectral measurements of ultraviolet (UV) irradiance and the albedo at a Camp located in the southern Ellsworth Mountains on the broad expanse of Union Glacier (700 m altitude, 79° 46′ S; 82° 52′W); about 1,000 km from the South Pole. The measurements were carried out by using a double monochromator-based spectroradiometer during a campaign (in December 2012) meant to weight up the effect of the local albedo on the UV irradiance. We found that the albedo measured at noon was about 0.95 in the UV and the visible part of the spectrum. This high surface reflectivity led to enhancements in the UV index under cloudless conditions of about 50% in comparison with snow free surfaces. Spectral measurements carried out elsewhere as well as estimates retrieved from the Ozone Monitoring Instrument (OMI) were used for further comparisons. PMID:24598906

UIT: Ultraviolet surface photometry of the spiral galaxy M74 (NGC 628)

NASA Technical Reports Server (NTRS)

Cornett, Robert H.; O'Connell, Robert W.; Greason, Michael R.; Offenberg, Joel D.; Angione, Ronald J.; Bohlin, Ralph C.; Cheng, K. P.; Roberts, Morton S.; Smith, Andrew M.; Smith, Eric P.

1994-01-01

Ultraviolet photometry, obtained from Ultraviolet Imaging Telescope (UIT) images at 1520 A (far-UV; magnitudes m(152)) and 2490 A (near-UV; magnitudes m(249)), of the spiral galaxy M74 (NGC 628) is compared with H-alpha, R, V, and B surface photometry and with models. M74's surface brightness profiles have a central peak with an exponential falloff; the exponential scale lengths of the profiles increase with decreasing wavelength for the broad-band images. The slope of the continuum-subtracted H-alpha profile is intermediate between those of far-UV and near-UV profiles, consistent with the related origins of H-alpha and UV emission in extreme Population I material. M74's color profiles all become bluer with increasing radius. The (m(152) - m(249)) color as measured by UIT averages near 0.0 (the color of an A0 star) over the central 20 sec radius and decreases from approximately -0.2 to approximately -0.4 from 20 sec to 200 sec. The spiral arms are the dominant component of the surface photometry colors; interarm regions are slightly redder. In the UV, M74's nuclear region resembles its disk/spiral arm material in colors and morphology, unlike galaxies such as M81. No UV 'bulge' is apparent. The m(152) - m(249) colors and models of M74's central region clearly demonstrate that there is no significant population of O or B stars present in the central 10 sec. M74's UV morphology and (m(152) - m(249)) color profiles are similar to those of M33, although M74 is approximately 0.5 mag redder. M81 has a smooth UV bulge which is much redder than the nuclear regions of M74 and M33. M74 is approximately 0.4 mag bluer than M81 in its outer disk, although M81 has bright UV sources only in spiral arms more than 5 kpc from its center. We investigate possible explanations for the color profiles of the galaxies and the differences among the galaxies: abundances; reddening due to internal dust; interplanetary magnetic field (IMF) variations, and the history of formation of the dominant generations of stars. Abundance and IMF variations do not produce large enough m(152) - m(249) or UV - V color differences. Comparing model UV/optical colors with those of M74 shows that M74's disk has undergone significant star formation over the past 500 Myr, and that either the star-formation history or the extinction varies systematically across M74's disk. Comparison of M74, M33, and M81 (UV - V) colors shows that M74 colors range from the bluest of M33's colors to the bluest of M81's. The failure of reddening models to cover the range of colors, and the known abundance range in such material, leads to the conclusion that star-formation history varies significantly as a function of radius in these galaxies, and that such variation is required to explain the range of colors observed in M74, M33, and M81.

GALEX Wide-field Ultraviolet Imaging of NGC 5128 (Centaurus-A)

NASA Technical Reports Server (NTRS)

Neff, S. G.; Shiminovich, D.; Martin, C. D.

2004-01-01

We present new wide-field ultraviolet (UV) observations of the nearby active galaxy NGC 5128 (Centaurus A). The GALEX images provide 3.5 sec - 5.5 sec resolution over a 1.2 degree field, in two broad bands (1350- 1800A and 1800-3000A, centered at 1550A and 2200A). We detect ultraviolet emission associated with the radio and X-ray jets in both bands, extending out to a distance of approx. 40kpc from the galaxy nucleus. We compare the radio, X-ray, and UV jets, and discuss the feasibility of jet-induced star formation. We show how the UV emission relates to the optical filaments: HI and CO clouds, stellar shells, X-ray arcs, and young star chains previously reported by other authors. In the central region of NGC 5128, we detect UV emission from young super-star-clusters and associated ionized gas located along the near edge and on the upper surface of the dusty warped disk. All of the UV emission in the galaxy appears to result from intense star formation in the disk; none appears to be associated with the old stellar population of the main galaxy body, and no UV emission from the AGN is detected. We estimate the numbers and ages of the massive young stars present, and the associated ionized gas masses. Finally, we compare Cen-A to high redshift radio galaxies which were much more numerous in the earlier universe. The GALEX satellite is a NASA Small Explorer, launched in April 2003. We gratefully acknowledge NASA's support for construction, operation, and science analysis for the GALEX mission.

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

PubMed

Raab, W

1980-04-15

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

FogEye UV Sensor System Performance Characteristics

DOT National Transportation Integrated Search

2004-03-01

The primary objective of the FogEye Evaluation Program is to determine whether coupled ultra-violet sources and detectors may provide enhancements to safety on the airport surface. The results of this effort will be used to complete the evaluation of...

Barred Ring Galaxy NGC 1291

NASA Image and Video Library

2005-05-05

This ultraviolet image left and visual image right from NASA Galaxy Evolution Explorer is of the barred ring galaxy NGC 1291. The VIS image is dominated by the inner disk and bar. The UV image is dominated by the low surface brightness outer arms.

The Ultraviolet Spectrograph (UVS) on ESA’s JUICE Mission

NASA Astrophysics Data System (ADS)

Gladstone, Randy; Retherford, K.; Steffl, A.; Eterno, J.; Davis, M.; Versteeg, M.; Greathouse, T.; Araujo, M.; Walther, B.; Persson, K.; Persyn, S.; Dirks, G.; McGrath, M.; Feldman, P.; Bagenal, F.; Spencer, J.; Schindhelm, E.; Fletcher, L.

2013-10-01

The Jupiter Icy Moons Explorer (JUICE) was selected in May 2012 as the first L-class mission of ESA’s Cosmic Vision Program. JUICE will launch in 2022 on a 7.6-year journey to the Jovian system, including a Venus and multiple Earth gravity assists, before entering Jupiter orbit in January 2030. JUICE will study the entire Jovian system for 3.5 years, concentrating on Europa, Ganymede, and Callisto, with the last 10 months spent in Ganymede orbit. The Ultraviolet Spectrograph (UVS) on JUICE was jointly selected by NASA and ESA as part of its ~130 kg payload of 11 scientific instruments. UVS is the fifth in a series of successful ultraviolet imaging spectrographs (Rosetta-Alice, New Horizons Pluto-Alice, LRO-LAMP) and is largely based on the most recent of these, Juno-UVS. It observes photons in the 55-210 nm wavelength range, at moderate spectral and spatial resolution along a 7.5-degree slit. A main entrance “airglow port” (AP) is used for most observations (e.g., airglow, aurora, surface mapping, and stellar occultations), while a separate “solar port” (SP) allows for solar occultations. Another aperture door, with a small hole through the centre, is used as a “high-spatial-resolution port” (HP) for detailed observations of bright targets. Time-tagging (pixel list mode) and programmable spectral imaging (histogram mode) allow for observational flexibility and optimal data management. As on Juno-UVS, the effects of penetrating electron radiation on electronic parts and data quality are substantially mitigated through contiguous shielding, filtering of pulse height amplitudes, management of high voltage settings, and careful use of radiation-hard, flight-tested parts. The science goals of UVS are to: 1) explore the atmospheres, plasma interactions, and surfaces of the Galilean satellites; 2) determine the dynamics, chemistry, and vertical structure of Jupiter’s upper atmosphere from equator to pole; and 3) investigate the Jupiter-Io connection by quantifying energy and mass flow in the Io atmosphere, neutral clouds, and torus. Here we present the salient features of the UVS instrument and describe the science we plan to address.

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

PubMed

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

1998-10-01

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

Ultraviolet Radiations: Skin Defense-Damage Mechanism.

PubMed

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

2017-01-01

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

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

NASA Astrophysics Data System (ADS)

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

2016-10-01

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

Ultraviolet-Ozone Cleaning of Semiconductor Surfaces

DTIC Science & Technology

1992-01-01

Bolon and Kunz (1) reported that UV light had the capability to depolymerize a variety of photoresist polymers. The polymer films were enclosed in a...placed between the UV light and the films, or when a nitrogen atmosphere was used instead of oxygen, the depolymerization was hindered. Thus, Bolon and...ozone cleaning rates. Bolon and Kunz (1), on the other hand, found that the rate of ozone depolymerization of photoresists did not change significantly

Ultraviolet-Ozone Cleaning of Semiconductor Surfaces

DTIC Science & Technology

1992-10-01

rooms and in the air ducts of air conditioning systems (7). In 1972, Bolon and Kunz (1) reported that UV light had the capability to depolymerize a...instead of oxygen, the depolymerization was hindered. Thus, Bolon and Kunz recognized that oxygen and wavelengths shorter than 300-nm played a role in the...that mild heat increases the UV/ozone cleaning rates. Bolon and Kunz (1), on the other hand, found that the rate of ozone depolymerization of

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

PubMed

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

1999-10-01

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

Occupational Skin Hazards From Ultraviolet (UV) Exposures

NASA Astrophysics Data System (ADS)

Urbach, F.; Wolbarsht, M. L.

1980-10-01

The various types of UV effects on the skin are classified according to the part of the spectrum and their beneficial or deleterious nature. Some hazardous ultraviolet sources used in industrial processes are described, and examples of photoallergy, phototoxicity, and photosensitization resulting from UV exposures are given. The incidence of skin cancer as a function of geographical location and exposure to sunlight is discussed in relation to natural and artificial exposures to long and short wavelength UV, especially in connection with tanning booths. The conclusion is reached that there is enough ultraviolet in a normal environment to propose a hazard, and additional ultraviolet exposure from industrial or consumer sources is not necessary, and should be eliminated wherever possible.

Occupational Skin Hazards From Ultraviolet (UV) Exposures

NASA Astrophysics Data System (ADS)

Urbach, F.; Wolbarsht, M. L.

1981-11-01

The various types of UV effects on the skin are classified according to the part of the spectrum and their beneficial or deleterious nature. Some hazardous ultraviolet sources used in industrial processes are described, and examples of photoallergy, phototoxicity, and photosensitization resulting from UV exposures are given. The incidence of skin cancer as a function of geographical location and exposure to sunlight is discussed in relation to natural and artificial exposures to long and short wavelength UV, especially in connection with tanning booths. The conclusion is reached that there is enough ultraviolet in a normal environment to propose a hazard, and additional ultraviolet exposure from industrial or consumer sources is not necessary, and should be eliminated wherever possible.

FogEye UV Sensor System Evaluation : Phase II Report

DOT National Transportation Integrated Search

2003-12-01

The primary objective of the FogEye Evaluation Program is to determine whether coupled ultra-violet sources and detectors may provide enhancements to safety on the airport surface. The results of this effort will be used to complete the evaluation of...

The Effectiveness of UV Irradiation on Vegetative Bacteria and Fungi Surface Contamination

EPA Science Inventory

Ultraviolet irradiation has commonly been used in the indoor environment to eliminate or control infectious diseases in medical care facilities. Heating, ventilating, and air-conditioning (HV AC) system components such as duct-liners, cooling coils, drip-pans, interior insulation...

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

NASA Astrophysics Data System (ADS)

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

2017-01-01

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

Statistical optimization of ultraviolet irradiate conditions for vitamin D₂ synthesis in oyster mushrooms (Pleurotus ostreatus) using response surface methodology.

PubMed

Wu, Wei-Jie; Ahn, Byung-Yong

2014-01-01

Response surface methodology (RSM) was used to determine the optimum vitamin D2 synthesis conditions in oyster mushrooms (Pleurotus ostreatus). Ultraviolet B (UV-B) was selected as the most efficient irradiation source for the preliminary experiment, in addition to the levels of three independent variables, which included ambient temperature (25-45°C), exposure time (40-120 min), and irradiation intensity (0.6-1.2 W/m2). The statistical analysis indicated that, for the range which was studied, irradiation intensity was the most critical factor that affected vitamin D2 synthesis in oyster mushrooms. Under optimal conditions (ambient temperature of 28.16°C, UV-B intensity of 1.14 W/m2, and exposure time of 94.28 min), the experimental vitamin D2 content of 239.67 µg/g (dry weight) was in very good agreement with the predicted value of 245.49 µg/g, which verified the practicability of this strategy. Compared to fresh mushrooms, the lyophilized mushroom powder can synthesize remarkably higher level of vitamin D2 (498.10 µg/g) within much shorter UV-B exposure time (10 min), and thus should receive attention from the food processing industry.

The ultraviolet environment of Mars: biological implications past, present, and future.

PubMed

Cockell, C S; Catling, D C; Davis, W L; Snook, K; Kepner, R L; Lee, P; McKay, C P

2000-08-01

A radiative transfer model is used to quantitatively investigate aspects of the martian ultraviolet radiation environment, past and present. Biological action spectra for DNA inactivation and chloroplast (photosystem) inhibition are used to estimate biologically effective irradiances for the martian surface under cloudless skies. Over time Mars has probably experienced an increasingly inhospitable photobiological environment, with present instantaneous DNA weighted irradiances 3.5-fold higher than they may have been on early Mars. This is in contrast to the surface of Earth, which experienced an ozone amelioration of the photobiological environment during the Proterozoic and now has DNA weighted irradiances almost three orders of magnitude lower than early Earth. Although the present-day martian UV flux is similar to that of early Earth and thus may not be a critical limitation to life in the evolutionary context, it is a constraint to an unadapted biota and will rapidly kill spacecraft-borne microbes not covered by a martian dust layer. Microbial strategies for protection against UV radiation are considered in the light of martian photobiological calculations, past and present. Data are also presented for the effects of hypothetical planetary atmospheric manipulations on the martian UV radiation environment with estimates of the biological consequences of such manipulations.

The ultraviolet environment of Mars: biological implications past, present, and future

NASA Technical Reports Server (NTRS)

Cockell, C. S.; Catling, D. C.; Davis, W. L.; Snook, K.; Kepner, R. L.; Lee, P.; McKay, C. P.

2000-01-01

A radiative transfer model is used to quantitatively investigate aspects of the martian ultraviolet radiation environment, past and present. Biological action spectra for DNA inactivation and chloroplast (photosystem) inhibition are used to estimate biologically effective irradiances for the martian surface under cloudless skies. Over time Mars has probably experienced an increasingly inhospitable photobiological environment, with present instantaneous DNA weighted irradiances 3.5-fold higher than they may have been on early Mars. This is in contrast to the surface of Earth, which experienced an ozone amelioration of the photobiological environment during the Proterozoic and now has DNA weighted irradiances almost three orders of magnitude lower than early Earth. Although the present-day martian UV flux is similar to that of early Earth and thus may not be a critical limitation to life in the evolutionary context, it is a constraint to an unadapted biota and will rapidly kill spacecraft-borne microbes not covered by a martian dust layer. Microbial strategies for protection against UV radiation are considered in the light of martian photobiological calculations, past and present. Data are also presented for the effects of hypothetical planetary atmospheric manipulations on the martian UV radiation environment with estimates of the biological consequences of such manipulations.

[The research of UV-responsive sensitivity enhancement of fluorescent coating films by MgF2 layer].

PubMed

Lu, Zhong-Rong; Ni, Zheng-Ji; Tao, Chun-Xian; Hong, Rui-Jin; Zhang, Da-Wei; Huang, Yuan-Shen

2014-03-01

A low cost and less complicated expansion approach of wavelength responses with a Lumogen phosphor coating was adopted, as they increased the quantum efficiency of CCD and CMOS detectors in ultra-violet by absorbing UV light and then re emitting visible light. In this paper, the sensitivity enhancement of fluorescence coatings was studied by adding an anti-reflection film or barrier film to reduce the loss of the scattering and reflection on the incident interface. The Lumogen and MgF2/Lumogen film were deposited on quartz glasses by physical vacuum deposition. The surface morphology, transmittance spectrum, reflectance spectrum and fluorescence emission spectrum were obtained by atomic force microscope (AFM), spectrophotometer and fluorescence spectrometer, respectively. The results indicated that MgF2 film had obvious positive effect on reducing scattering and reflection loss in 500-700 nm, and enhancing the absorption of Lumogen coating in ultraviolet spectrum. Meanwhile, the fluorescent emission intensity had a substantial increase by smoothing the film surface and thus reducing the light scattering. At the same time, the MgF2 layer could protect Lumogen coating from damaging and contamination, which give a prolong lifetime of the UV-responsive CCD sensors with fluorescent coatings.

Glass-Based Transparent Conductive Electrode: Its Application to Visible-to-Ultraviolet Light-Emitting Diodes.

PubMed

Lee, Tae Ho; Kim, Kyeong Heon; Lee, Byeong Ryong; Park, Ju Hyun; Schubert, E Fred; Kim, Tae Geun

2016-12-28

Nitride-based ultraviolet light-emitting diodes (UV LEDs) are promising replacements for conventional UV lamps. However, the external quantum efficiency of UV LEDs is much lower than for visible LEDs due to light absorption in the p-GaN contact and electrode layers, along with p-AlGaN growth and doping issues. To minimize such absorption, we should obtain direct ohmic contact to p-AlGaN using UV-transparent ohmic electrodes and not use p-GaN as a contact layer. Here, we propose a glass-based transparent conductive electrode (TCE) produced using electrical breakdown (EBD) of an AlN thin film, and we apply the thin film to four (Al)GaN-based visible and UV LEDs with thin buffer layers for current spreading and damage protection. Compared to LEDs with optimal ITO contacts, our LEDs with AlN TCEs exhibit a lower forward voltage, higher light output power, and brighter light emission for all samples. The ohmic transport mechanism for current injection and spreading from the metal electrode to p-(Al)GaN layer via AlN TCE is also investigated by analyzing the p-(Al)GaN surface before and after EBD.

UV-Resistant Non-Spore-Forming Bacteria From Spacecraft-Assembly Facilities

NASA Technical Reports Server (NTRS)

Venkateswaran, Kasthuri

2008-01-01

Four species of non-spore-forming bacteria collected from clean-room surfaces in spacecraft-assembly facilities could survive doses of ultraviolet (UV) radiation that would suffice to kill most known cultivable bacterial species. In a previous study, high UV resistance was found in spores of the SAFR-032 strain of Bacillus pumilus, as reported in "Ultraviolet- Resistant Bacterial Spores," NASA Tech Briefs, Vol. 31, No. 9 (September 2007), page 94. These studies are parts of a continuing effort to understand the survival of hardy species of bacteria under harsh conditions, and develop means of sterilizing spacecraft to prevent biocontamination of Mars that could in turn interfere with future life detection missions. The four species investigated were Arthrobacter sp. KSC_Ak2i, Microbacterium schleiferi LMA_AkK1, Brevundimonas diminuta KSC_Ak3a, and Sphingomonas trueperi JSC_Ak7-3. In the study, cells of these species were mixed into Atacama Desert soil (to elucidate the shadowing effect of soil particles) and the resulting mixtures were tested both in solution and in a desiccated state under simulated Martian atmospheric and UV conditions. The UV-survival indices of Arthrobacter sp. and Microbacterium schleiferi were found to be comparable to those of Bacillus pumilus spores.

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

Aadila, A., E-mail: aadilaazizali@gmail.com; Afaah, A. N.; Asib, N. A. M.

Poly(methyl methacrylate) (PMMA) films were deposited on glass substrate by sol-gel spin-coating method. The films were annealed for 10 minutes in furnace at different annealing temperature of room temperature, 50, 100, 150 and 200 °C. The effect of annealing temperatures to the surface and optical properties of PMMA films spin-coated on the substrate were investigated by Atomic Force Microscope (AFM) and Ultraviolet-Visible (UV-Vis) Spectroscopy. It was observed in AFM analysis all the annealed films show excellent smooth surface with zero roughness. All the samples demonstrate a high transmittance of 80% in UV region as shown in UV-Vis measurement. Highly transparentmore » films indicate the films are good optical properties and could be applied in various optical applications and also in non-linear optics.« less

Satellite estimation of incident photosynthetically active radiation using ultraviolet reflectance

NASA Technical Reports Server (NTRS)

Eck, Thomas F.; Dye, Dennis G.

1991-01-01

A new satellite remote sensing method for estimating the amount of photosynthetically active radiation (PAR, 400-700 nm) incident at the earth's surface is described and tested. Potential incident PAR for clear sky conditions is computed from an existing spectral model. A major advantage of the UV approach over existing visible band approaches to estimating insolation is the improved ability to discriminate clouds from high-albedo background surfaces. UV spectral reflectance data from the Total Ozone Mapping Spectrometer (TOMS) were used to test the approach for three climatically distinct, midlatitude locations. Estimates of monthly total incident PAR from the satellite technique differed from values computed from ground-based pyranometer measurements by less than 6 percent. This UV remote sensing method can be applied to estimate PAR insolation over ocean and land surfaces which are free of ice and snow.

ULTRAVIOLET DISINFECTION STUDIES WITH CCL LISTED MICROORGANISMS

EPA Science Inventory

Resistance to ultraviolet (UV) disinfection is an essential aspect regarding all microbial groups listed on the CCL. The U.S. drinking water industry is interested in including UV light treatment as an amendment to conventional treatment for disinfecting water supplies. UV disi...

Isolation and characterization of ultraviolet light-sensitive mutants of the blue-green alga Anacystis nidulans.

NASA Technical Reports Server (NTRS)

Asato, Y.

1972-01-01

Three independently isolated ultraviolet light sensitive (uvs) mutants of Anacystis nidulans were characterized. Strain uvs-1 showed the highest sensitivity to UV by its greatly reduced photoreactivation capacity following irradiation. Pretreatment with caffeine suppressed the dark-survival curve of strain uvs-1, thus indicating the presence of excision enzymes involved in dark repair. Under 'black' and 'white' illumination, strain uvs-1 shows photorecovery properties comparable with wild-type cultures. Results indicate that strains uvs-1, uvs-35, and uvs-88 are probably genetically distinct UV-sensitive mutants.

Intraocular and crystalline lens protection from ultraviolet damage.

PubMed

Sliney, David H

2011-07-01

Although the risks of excess solar ultraviolet (UV) exposure of the skin are well recognized, the need for eye protection is frequently overlooked, or when sunglasses are also recommended, specific guidance is wrong or is not explained. Guidance from the World Health Organization at its InterSun webpage advises people to wear "wrap-around" sunglasses under many conditions. The objective of this study was to examine the need for UV filtration in prescription lenses, contact lenses, and sunglasses. The geometry of UV exposure of both eyes, solar position, ground reflection, pupil size, and lid opening were studied. Because an accurate determination of cumulative ocular exposure is difficult, the cornea itself can serve as a biologic dosimeter, because photokeratitis is not experienced on a daily basis but does under certain ground-surface and sunlight conditions. From a knowledge of the UV-threshold dose required to produce photokeratitis, we have an upper level of routine ocular exposure to ambient UV. From ambient UV measurements and observed photokeratitis, the upper limits of UV exposure of the crystalline lens or an intraocular lens implant are estimated. The risk of excess UV exposure of the germinative cells of the lens is greatest from the side. Sunglasses can actually increase UV exposure of the germinative region of the crystalline lens and the corneal limbus by disabling the eyes' natural protective mechanisms of lid closure and pupil constriction! The level of UV-A risk is difficult to define. Proper UV-absorbing contact lenses offer the best mode for filtering needless exposure of UV radiation of the lens and limbus.

Spatiotemporal exposure modeling of ambient erythemal ultraviolet radiation.

PubMed

VoPham, Trang; Hart, Jaime E; Bertrand, Kimberly A; Sun, Zhibin; Tamimi, Rulla M; Laden, Francine

2016-11-24

Ultraviolet B (UV-B) radiation plays a multifaceted role in human health, inducing DNA damage and representing the primary source of vitamin D for most humans; however, current U.S. UV exposure models are limited in spatial, temporal, and/or spectral resolution. Area-to-point (ATP) residual kriging is a geostatistical method that can be used to create a spatiotemporal exposure model by downscaling from an area- to point-level spatial resolution using fine-scale ancillary data. A stratified ATP residual kriging approach was used to predict average July noon-time erythemal UV (UV Ery ) (mW/m 2 ) biennially from 1998 to 2012 by downscaling National Aeronautics and Space Administration (NASA) Total Ozone Mapping Spectrometer (TOMS) and Ozone Monitoring Instrument (OMI) gridded remote sensing images to a 1 km spatial resolution. Ancillary data were incorporated in random intercept linear mixed-effects regression models. Modeling was performed separately within nine U.S. regions to satisfy stationarity and account for locally varying associations between UV Ery and predictors. Cross-validation was used to compare ATP residual kriging models and NASA grids to UV-B Monitoring and Research Program (UVMRP) measurements (gold standard). Predictors included in the final regional models included surface albedo, aerosol optical depth (AOD), cloud cover, dew point, elevation, latitude, ozone, surface incoming shortwave flux, sulfur dioxide (SO 2 ), year, and interactions between year and surface albedo, AOD, cloud cover, dew point, elevation, latitude, and SO 2 . ATP residual kriging models more accurately estimated UV Ery at UVMRP monitoring stations on average compared to NASA grids across the contiguous U.S. (average mean absolute error [MAE] for ATP, NASA: 15.8, 20.3; average root mean square error [RMSE]: 21.3, 25.5). ATP residual kriging was associated with positive percent relative improvements in MAE (0.6-31.5%) and RMSE (3.6-29.4%) across all regions compared to NASA grids. ATP residual kriging incorporating fine-scale spatial predictors can provide more accurate, high-resolution UV Ery estimates compared to using NASA grids and can be used in epidemiologic studies examining the health effects of ambient UV.

EXPERIMENT - APOLLO 16 (UV)

NASA Image and Video Library

1972-06-06

S72-40820 (21 April 1972) --- A color enhancement of a photograph taken on ultra-violet light showing the spectrum of the upper atmosphere of Earth and geocorona. The bright horizontal line is far ultra-violet emission (1216 angstrom) of hydrogen extending 10 degrees (40,000 miles) either side of Earth. The knobby vertical line shows several ultra-violet emissions from Earth's sunlit atmosphere, each "lump" being produced by one type gas (oxygen, nitrogen, helium, etc.). The spectral dispersion is about 10 angstrom per millimeter on this enlargement. The UV camera/spectrograph was operated on the lunar surface by astronaut John W. Young, commander of the Apollo 16 lunar landing mission. It was designed and built at the Naval Research Laboratory, Washington, D.C. While astronauts Young and Charles M. Duke Jr., lunar module pilot, descended in the Lunar Module (LM) "Orion" to explore the Descartes highlands region of the moon, astronaut Thomas K. Mattingly II, command module pilot, remained with the Command and Service Modules (CSM) "Casper" in lunar orbit.

Astronaut John Young in shadow of Lunar Module behind ultraviolet camera

NASA Image and Video Library

1972-04-22

AS16-114-18439 (22 April 1972) --- Astronaut Charles M. Duke Jr., lunar module pilot, stands in the shadow of the Lunar Module (LM) behind the ultraviolet (UV) camera which is in operation. This photograph was taken by astronaut John W. Young, commander, during the mission's second extravehicular activity (EVA). The UV camera's gold surface is designed to maintain the correct temperature. The astronauts set the prescribed angles of azimuth and elevation (here 14 degrees for photography of the large Magellanic Cloud) and pointed the camera. Over 180 photographs and spectra in far-ultraviolet light were obtained showing clouds of hydrogen and other gases and several thousand stars. The United States flag and Lunar Roving Vehicle (LRV) are in the left background. While astronauts Young and Duke descended in the Apollo 16 Lunar Module (LM) "Orion" to explore the Descartes highlands landing site on the moon, astronaut Thomas K. Mattingly II, command module pilot, remained with the Command and Service Modules (CSM) "Casper" in lunar orbit.

Astronaut Charles M. Duke, Jr., in shadow of Lunar Module behind ultraviolet camera

NASA Technical Reports Server (NTRS)

1972-01-01

Astronaut Charles M. Duke, Jr., lunar module pilot, stands in the shadow of the Lunar Module (LM) behind the ultraviolet (UV) camera which is in operation. This photograph was taken by astronaut John W. Young, mission commander, during the mission's second extravehicular activity (EVA-2). The UV camera's gold surface is designed to maintain the correct temperature. The astronauts set the prescribed angles of azimuth and elevation (here 14 degrees for photography of the large Magellanic Cloud) and pointed the camera. Over 180 photographs and spectra in far-ultraviolet light were obtained showing clouds of hydrogen and other gases and several thousand stars. The United States flag and Lunar Roving Vehicle (LRV) are in the left background. While astronauts Young and Duke descended in the Apollo 16 Lunar Module (lm) 'Orion' to explore the Descartes highlands landing site on the Moon, astronaut Thomas K. Mattingly II, command module pilot, remained with the Command and Service Modules (csm) 'Casper' in lunar orbit.

Performance Assessment of a Plate Beam Splitter for Deep-Ultraviolet Raman Measurements with a Spatial Heterodyne Raman Spectrometer.

PubMed

Lamsal, Nirmal; Angel, S Michael

2017-06-01

In earlier works, we demonstrated a high-resolution spatial heterodyne Raman spectrometer (SHRS) for deep-ultraviolet (UV) Raman measurements, and showed its ability to measure UV light-sensitive compounds using a large laser spot size. We recently modified the SHRS by replacing the cube beam splitter (BS) with a custom plate beam splitter with higher light transmission, an optimized reflectance/transmission ratio, higher surface flatness, and better refractive index homogeneity than the cube beam splitter. Ultraviolet Raman measurements were performed using a SHRS modified to use the plate beam splitter and a matching compensator plate and compared to the previously described cube beam splitter setup. Raman spectra obtained using the modified SHRS exhibit much higher signals and signal-to-noise (S/N) ratio and show fewer spectral artifacts. In this paper, we discuss the plate beam splitter SHRS design features, the advantages over previous designs, and discuss some general SHRS issues such as spectral bandwidth, S/N ratio characteristics, and optical efficiency.

Surface abundance and the hunt for stratification in chemically peculiar hot subdwarfs: PG 0909+276 and UVO 0512-08

NASA Astrophysics Data System (ADS)

Wild, J. F.; Jeffery, C. S.

2018-01-01

Edelmann identified two chemically peculiar hot subdwarfs, PG 0909+276 and UVO 0512-08, as having very high overabundances of iron-group elements. We obtained high-resolution ultraviolet spectroscopy in order to measure abundances of species not observable in the optical, and to seek evidence for chemical stratification in the photosphere. Abundances were measured in three wavelength regions; the optical 3900-6900 Å range was re-analysed to confirm consistency with that analysed by Edelmann. Ultraviolet spectra were obtained with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope, covering the far-UV (1140-1740 Å) and the near-UV (1740-2500 Å). We computed a grid of theoretical local thermodynamic equilibrium spectra to find basic parameters (effective temperatures, surface gravity, surface hydrogen and helium fractions). We measured abundances using a spectral-synthesis approach in each wavelength range. We confirm that several iron-group metals are highly enriched, including cobalt, copper and zinc, relative to typical sdB stars. We detect gallium, germanium, tin and lead, similar to analysis of ultraviolet spectra of some other sdB stars. Our results confirm that PG 0909+276 and UVO 0512-08 exhibit peculiarities which make them distinct from both the normal H-rich sdB and intermediate He-rich sdB stars. The process which leads to this particular composition has still to be identified.

STS-93 Tognini and Hawley pose with the SWUIS on the middeck of Columbia

NASA Image and Video Library

2013-11-18

STS093-347-027 (23-27 July 1999) --- Astronauts Steven A. Hawley (left) and Michel Tognini, mission specialists, are pictured with the Southwest Ultraviolet Imaging System (SWUIS) on the middeck of the Space Shuttle Columbia. SWUIS was used during the mission to image planets and other solar system bodies in order to explore their atmospheres and surfaces in ultraviolet (UV) region of the spectrum, which astronomers value for diagnostic work. Tognini represents the Centre National d'Etudes Spatiales (CNES) of France.

Evaluation of thermal control coatings for use on solar dynamic radiators in low earth orbit

NASA Technical Reports Server (NTRS)

Dever, Joyce A.; Rodriguez, Elvin; Slemp, Wayne S.; Stoyack, Joseph E.

1991-01-01

Thermal control coatings with high thermal emittance and low solar absorptance are needed for Space Station Freedom (SSF) solar dynamic power module radiator (SDR) surfaces for efficient heat rejection. Additionally, these coatings must be durable to low earth orbital (LEO) environmental effects of atomic oxygen, ultraviolet radiation and deep thermal cycles which occur as a result of start-up and shut-down of the solar dynamic power system. Eleven candidate coatings were characterized for their solar absorptance and emittance before and after exposure to ultraviolet (UV) radiation (200 to 400 nm), vacuum UV (VUV) radiation (100 to 200 nm) and atomic oxygen. Results indicated that the most durable and best performing coatings were white paint thermal control coatings Z-93, zinc oxide pigment in potassium silicate binder, and YB-71, zinc orthotitanate pigment in potassium silicate binder. Optical micrographs of these materials exposed to the individual environmental effects of atomic oxygen and vacuum thermal cycling showed that no surface cracking occurred.

Martian atmospheric O3 retrieval development for the NOMAD-UVIS spectrometer

NASA Astrophysics Data System (ADS)

Hewson, W.; Mason, J. P.; Leese, M.; Hathi, B.; Holmes, J.; Lewis, S. R.; Iriwin, P. G. J.; Patel, M. R.

2017-09-01

The composition of atmospheric trace gases and aerosols is a highly variable and poorly constrained component of the martian atmosphere, and by affecting martian climate and UV surface dose, represents a key parameter in the assessment of suitability for martian habitability. The ExoMars Trace Gas Orbiter (TGO) carries the Open University (OU) designed Ultraviolet and VIsible Spectrometer (UVIS) instrument as part of the Belgian-led Nadir and Occultation for MArs Discovery (NOMAD) spectrometer suite. NOMAD will begin transmitting science observations of martian surface and atmosphere back-scattered UltraViolet (UV) and visible radiation in Spring 2018, which will be processed to derive spatially and temporally averaged atmospheric trace gas and aerosol concentrations, intended to provide a better understanding of martian atmospheric photo-chemistry and dynamics, and will also improve models of martian atmospheric chemistry, climate and habitability. Work presented here illustrates initial development and testing of the OU's new retrieval algorithm for determining O3 and aerosol concentrations from the UVIS instrument.

Evaluation of thermal control coatings for use on solar dynamic radiators in low Earth orbit

NASA Technical Reports Server (NTRS)

Dever, Joyce A.; Rodriguez, Elvin; Slemp, Wayne S.; Stoyack, Joseph E.

1991-01-01

Thermal control coatings with high thermal emittance and low solar absorptance are needed for Space Station Freedom (SSF) solar dynamic power module radiator (SDR) surfaces for efficient heat rejection. Additionally, these coatings must be durable to low earth orbital (LEO) environmental effects of atomic oxygen, ultraviolet radiation and deep thermal cycles which occur as a result of start-up and shut-down of the solar dynamic power system. Eleven candidate coatings were characterized for their solar absorptance and emittance before and after exposure to ultraviolet (UV) radiation (200 to 400 nm), vacuum UV (VUV) radiation (100 to 200 nm) and atomic oxygen. Results indicated that the most durable and best performing coatings were white paint thermal control coatings Z-93, zinc oxide pigment in potassium silicate binder, and YB-71, zinc orthotitanate pigment in potassium silicate binder. Optical micrographs of these materials exposed to the individual environmental effects of atomic oxygen and vacuum thermal cycling showed that no surface cracking occurred.

Synthesis and characterization of Ni doped ZnO nanoparticles

NASA Astrophysics Data System (ADS)

Tamgadge, Y. S.; Gedam, P. P.; Ganorkar, R. P.; Mahure, M. A.; Pahurkar, V. G.; Muley, G. G.

2018-05-01

In this paper, we present synthesis of L-valine assisted surface modification of Ni doped ZnO nanoparticles (NPs) using chemical precipitation method. Samples were calcined at 500oC for 2h. Uncalcined and calcined samples were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and ultraviolet-visible (UV-vis) spectroscopy. Ni doped ZnO NPs with average particle size of 8 nm have been successfully obtained using L-valine as surface modifying agent. Increase in the particle size was observed after the calcination. XRD and TEM studies confirmed the purity, surface morphology and hexagonal wurtzite crystal structure of ZnO NPs. UV-vis spectroscopy indicated the blue shift of excitons absorption wavelength and surface modification by L-valine.

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

NASA Astrophysics Data System (ADS)

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.

Ultraviolet Imaging Telescope observations of the ScI galaxy NGC 628 (M74)

NASA Technical Reports Server (NTRS)

Chen, Peter C.; Cornett, Robert H.; Roberts, Morton S.; Bohlin, Ralph C.; Neff, Susan G.; O'Connell, Robert W.; Parise, Ronald A.; Smith, Andrew M.; Stecher, Theodore P.

1992-01-01

Ultraviolet images of NGC 628 at 1520 and 2490 A show that the nucleus has an oblong appearance and that the arms and disk exhibit features not seen in blue or H-alpha images. Aperture photometry of the nucleus gives results that are compatible with observations in other bandpasses and with models. The spiral arms appear more symmetrical in the UV than in other colors; in particular, two gaps are seen on either side of the nucleus. Combined UV and radio data appear to support a large-scale collective phenomenon, perhaps a quasi-static spiral structure mechanism, as being the dominant mode of spiral formation in this galaxy. We report the detection of a low surface brightness object at a distance of 7.6 arcmin southwest of the nucleus.

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

NASA Astrophysics Data System (ADS)

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.

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

NASA Astrophysics Data System (ADS)

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

2012-02-01

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 all-sky 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 all-sky 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.

Employment of a metal microgrid as a front electrode in a sandwich-structured photodetector.

PubMed

Zhang, Junying; Cai, Chao; Pan, Feng; Hao, Weichang; Zhang, Weiwei; Wang, Tianmin

2009-07-01

A highly UV-transparent metal microgrid was prepared and employed as the front electrode in a sandwich-structured ultraviolet (UV) photodetector using TiO(2) thin film as the semiconductor layer. The photo-generated charger carriers travel a shorter distance before reaching the electrodes in comparison with a photodetector using large-spaced interdigitated metal electrodes (where distance between fingers is several to tens of micrometers) on the surface of the semiconductor film. This photodetector responds to UV light irradiation, and the photocurrent intensity increases linearly with the irradiation intensity below 0.2 mW/cm(2).

Reversible Hydrophobic to Hydrophilic Transition in Graphene via Water Splitting Induced by UV Irradiation

PubMed Central

Xu, Zhemi; Ao, Zhimin; Chu, Dewei; Younis, Adnan; Li, Chang Ming; Li, Sean

2014-01-01

Although the reversible wettability transition between hydrophobic and hydrophilic graphene under ultraviolet (UV) irradiation has been observed, the mechanism for this phenomenon remains unclear. In this work, experimental and theoretical investigations demonstrate that the H2O molecules are split into hydrogen and hydroxyl radicals, which are then captured by the graphene surface through chemical binding in an ambient environment under UV irradiation. The dissociative adsorption of H2O molecules induces the wettability transition in graphene from hydrophobic to hydrophilic. Our discovery may hold promise for the potential application of graphene in water splitting. PMID:25245110

Accelerated Solar-UV Test Chamber

NASA Technical Reports Server (NTRS)

Gupta, A.; Laue, E. G.

1984-01-01

Medium-pressure mercury-vapor lamps provide high ratio of ultraviolet to total power. Chamber for evaluating solar-ultraviolet (UV) radiation damage permits accelerated testing without overheating test specimens.

Development and future of ultraviolet light-emitting diodes: UV-LED will replace the UV lamp

NASA Astrophysics Data System (ADS)

Muramoto, Yoshihiko; Kimura, Masahiro; Nouda, Suguru

2014-06-01

Ultraviolet light-emitting diodes (UV-LEDs) have started replacing UV lamps. The power per LED of high-power LED products has reached 12 W (14 A), which is 100 times the values observed ten years ago. In addition, the cost of these high-power LEDs has been decreasing. In this study, we attempt to understand the technologies and potential of UV-LEDs.

Ultraviolet Spectra of Two Magnetic White Dwarfs and Ultraviolet Spectra of Subluminous Objects Found in the Kiso Schmidt Survey and Ultraviolet Absorptions in the Spectra of DA White Dwarfds

NASA Technical Reports Server (NTRS)

Wegner, Gary A.

1988-01-01

Research under NASA Grant NAG5-287 has carried out a number of projects in conjunction with the International Ultraviolet Explorer (IUE) satellite. These include: (1) studies of the UV spectra of DA white dwarfs which show quasi-molecular bands of H2 and H2(+); (2) the peculiar star HR6560; (3) the UV spectra of two magnetic white dwarfs that also show the quasi-molecular features; (4) investigations of the UV spectra of subluminous stars, primarily identified from visual wavelength spectroscopy in the Kiso survey of UV excess stars, some of which show interesting metal lines in their UV spectra; and (5) completion of studies of UV spectra of DB stars. The main result of this research has been to further knowledge of the structure and compositions of subluminous stars which helps cast light on their formation and evolution.

Development of a low cost UV index datalogger and comparison between UV index sensors

NASA Astrophysics Data System (ADS)

Gomes, L. M.; Ventura, L.

2018-02-01

Ultraviolet radiation (UVR) is the part of radiation emitted by the Sun, with range between 280 nm and 400 nm, and that reaches the Earth's surface. The UV rays are essential to the human because it stimulates the production of vitamin D but this radiation may be related to several health problems, including skin cancer and ocular diseases like pterygium, photokeratitis, cataract and more. To inform people about UV radiation, it is adopted the Ultraviolet Index (UVI). This UVI consists in a measure of solar UV radiation level, which contributes to cause sunburn on skin, also known as Erythema, and is indicated as an integer number between 1 and 14, associated to categories from low to extreme respectively. The aim of this work was to develop a low cost UVI datalogger capable of measuring three different UVI sensors simultaneously, record their data with timestamp and serve the measures online through a dedicated server, so general public can access their data and see the current UV radiation conditions. We also compared three different UVI sensors (SGlux UV cosine, Skye SKU440 and SiLabs SI1145) between them and with meteorological models during a period of months to verify their compliance. With five months data, we could verify the sensors working characteristics and decide which among them are the most suitable for research purposes.

Nonthermal combined ultraviolet and vacuum-ultraviolet curing process for organosilicate dielectrics

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

Zheng, H.; Guo, X.; Pei, D.

2016-06-13

Porous SiCOH films are of great interest in semiconductor fabrication due to their low-dielectric constant properties. Post-deposition treatments using ultraviolet (UV) light on organosilicate thin films are required to decompose labile pore generators (porogens) and to ensure optimum network formation to improve the electrical and mechanical properties of low-k dielectrics. The goal of this work is to choose the best vacuum-ultraviolet photon energy in conjunction with vacuum ultraviolet (VUV) photons without the need for heating the dielectric to identify those wavelengths that will have the most beneficial effect on improving the dielectric properties and minimizing damage. VUV irradiation between 8.3more » and 8.9 eV was found to increase the hardness and elastic modulus of low-k dielectrics at room temperature. Combined with UV exposures of 6.2 eV, it was found that this “UV/VUV curing” process is improved compared with current UV curing. We show that UV/VUV curing can overcome drawbacks of UV curing and improve the properties of dielectrics more efficiently without the need for high-temperature heating of the dielectric.« less

Ultraviolet spectral reflectance of carbonaceous materials

NASA Astrophysics Data System (ADS)

Applin, Daniel M.; Izawa, Matthew R. M.; Cloutis, Edward A.; Gillis-Davis, Jeffrey J.; Pitman, Karly M.; Roush, Ted L.; Hendrix, Amanda R.; Lucey, Paul G.

2018-06-01

A number of planetary spacecraft missions have carried instruments with sensors covering the ultraviolet (UV) wavelength range. However, there exists a general lack of relevant UV reflectance laboratory data to compare against these planetary surface remote sensing observations in order to make confident material identifications. To address this need, we have systematically analyzed reflectance spectra of carbonaceous materials in the 200-500 nm spectral range, and found spectral-compositional-structural relationships that suggest this wavelength region could distinguish between otherwise difficult-to-identify carbon phases. In particular (and by analogy with the infrared spectral region), large changes over short wavelength intervals in the refractive indices associated with the trigonal sp2π-π* transition of carbon can lead to Fresnel peaks and Christiansen-like features in reflectance. Previous studies extending to shorter wavelengths also show that anomalous dispersion caused by the σ-σ* transition associated with both the trigonal sp2 and tetrahedral sp3 sites causes these features below λ = 200 nm. The peak wavelength positions and shapes of π-π* and σ-σ* features contain information on sp3/sp2, structure, crystallinity, and powder grain size. A brief comparison with existing observational data indicates that the carbon fraction of the surface of Mercury is likely amorphous and submicroscopic, as is that on the surface of the martian satellites Phobos and Deimos, and possibly comet 67P/Churyumov-Gerasimenko, while further coordinated observations and laboratory experiments should refine these feature assignments and compositional hypotheses. The new laboratory diffuse reflectance data reported here provide an important new resource for interpreting UV reflectance measurements from planetary surfaces throughout the solar system, and confirm that the UV can be rich in important spectral information.

The role of a generalized ultraviolet cue for blackbird food selection.

PubMed

Werner, Scott J; Tupper, Shelagh K; Carlson, James C; Pettit, Susan E; Ellis, Jeremy W; Linz, George M

2012-07-16

Birds utilize ultraviolet (UV) wavelengths for plumage signaling and sexual selection. Ultraviolet cues may also be used for the process of avian food selection. The aim of our study was to investigate whether a UV cue and a postingestive repellent can be used to condition food avoidance in red-winged blackbirds (Agelaius phoeniceus). We found that birds conditioned with an UV-absorbent, postingestive repellent subsequently avoided UV-absorbent food. Thus, the UV-absorbent cue (coupled with 0-20% of the conditioned repellent concentration) was used to maintain avoidance for up to 18 days post-conditioning. Similarly, birds conditioned with the UV-absorbent, postingestive repellent subsequently avoided UV-reflective food. Thus, conditioned avoidance of an UV-absorbent cue can be generalized to an unconditioned, UV-reflective cue for nutrient selection and toxin avoidance. These findings support the hypothesized function of UV vision for avian food selection, the implications of which remain to be explored for the sensory and behavioral ecology within agronomic and natural environments. Published by Elsevier Inc.

Change in surface properties of zirconia and initial attachment of osteoblastlike cells with hydrophilic treatment.

PubMed

Watanabe, Hiroaki; Saito, Kensuke; Kokubun, Katsutoshi; Sasaki, Hodaka; Yoshinari, Masao

2012-01-01

The objectives of this study were to characterize change in surface properties of tetragonal zirconia polycrystals (TZP) after hydrophilic treatment, and to determine the effect of such changes on initial attachment of osteoblast-like cells. Roughened surfaces were produced by alumina-blasting and acid-etching. Hydrophilic treatment comprised application of immediately after blasting and acid-etching (Blast/Etch), oxygen plasma (O2-Plasma), ultraviolet light (UV). Specimens stored in air were used as a control. The water contact angle was determined and surface analysis was performed using an X-ray photoelectron spectroscopy. Blast/Etch, O2-Plasma and UV specimens showed superhydrophilicity, and these hydrophilic treatments to TZP elicited a marked decrease in carbon content and an increase in hydroxyl groups. Hydrophilic treatments enhanced initial attachment of osteoblast-like cells and a change in cell morphologies. These results indicate that Blast/Etch, O2-Plasma, or UV treatment has potential in the creation and maintenance of superhydrophilic surfaces and enhancing initial attachment of osteoblast-like cells.

Photodegradation of the antimicrobial triclocarban in aqueous systems under ultraviolet radiation.

PubMed

Ding, Shi-Ling; Wang, Xi-Kui; Jiang, Wen-Qiang; Meng, Xia; Zhao, Ru-Song; Wang, Chen; Wang, Xia

2013-05-01

This work aimed to investigate the effectiveness of ultraviolet (UV) radiation on the degradation of the antimicrobial triclocarban (TCC). We investigated the effects of several operational parameters, including solution pH, initial TCC concentration, photocatalyst TiO₂ loading, presence of natural organic matter, and most common anions in surface waters (e.g., bicarbonate, nitrate, and sulfate). The results showed that UV radiation was very effective for TCC photodegradation and that the photolysis followed pseudo-first-order kinetics. The TCC photolysis rate was pH dependent and favored at high pH. A higher TCC photolysis rate was observed by direct photolysis than TiO₂ photocatalysis. The presence of the inorganic ions bicarbonate, nitrate, and sulfate hindered TCC photolysis. Negative effects on TCC photolysis were also observed by the addition of humic acid due to competitive UV absorbance. The main degradation products of TCC were tentatively identified by gas chromatograph with mass spectrometer, and a possible degradation pathway of TCC was also proposed.

Ultraviolet Imaging Telescope observations of the Crab Nebula

NASA Technical Reports Server (NTRS)

Hennessy, Gregory S.; O'Connell, Robert W.; Cheng, Kwang P.; Bohlin, Ralph C.; Collins, Nicholas R.; Gull, Theodore P.; Hintzen, Paul; Isensee, Joan E.; Landsman, Wayne B.; Roberts, Morton S.

1992-01-01

We obtained ultraviolet images of the Crab Nebula with the Ultraviolet Imaging Telescope during the Astro-1 Space Shuttle mission in 1990 December. The UV continuum morphology of the Crab is generally similar to that in the optical region, but the wispy structures are less conspicuous in the UV and X-ray. UV line emission from the thermal filaments is not strong. UV spectral index maps with a resolution of 10 arcsecs show a significant gradient across the nebula, with the outer parts being redder, as expected from synchrotron losses. The location of the bluest synchrotron continuum does not coincide with the pulsar.

Cavitation induced Becquerel effect.

PubMed

Prevenslik, T V

2003-06-01

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

Effect of core quantum-dot size on power-conversion-efficiency for silicon solar-cells implementing energy-down-shift using CdSe/ZnS core/shell quantum dots.

PubMed

Baek, Seung-Wook; Shim, Jae-Hyoung; Seung, Hyun-Min; Lee, Gon-Sub; Hong, Jin-Pyo; Lee, Kwang-Sup; Park, Jea-Gun

2014-11-07

Silicon solar cells mainly absorb visible light, although the sun emits ultraviolet (UV), visible, and infrared light. Because the surface reflectance of a textured surface with SiNX film on a silicon solar cell in the UV wavelength region (250-450 nm) is higher than ∼27%, silicon solar-cells cannot effectively convert UV light into photo-voltaic power. We implemented the concept of energy-down-shift using CdSe/ZnS core/shell quantum-dots (QDs) on p-type silicon solar-cells to absorb more UV light. CdSe/ZnS core/shell QDs demonstrated clear evidence of energy-down-shift, which absorbed UV light and emitted green-light photoluminescence signals at a wavelength of 542 nm. The implementation of 0.2 wt% (8.8 nm QDs layer) green-light emitting CdSe/ZnS core/shell QDs reduced the surface reflectance of the textured surface with SiNX film on a silicon solar-cell from 27% to 15% and enhanced the external quantum efficiency (EQE) of silicon solar-cells to around 30% in the UV wavelength region, thereby enhancing the power conversion efficiency (PCE) for p-type silicon solar-cells by 5.5%.

Reusable hydroxyapatite nanocrystal sensors for protein adsorption.

PubMed

Tagaya, Motohiro; Ikoma, Toshiyuki; Hanagata, Nobutaka; Chakarov, Dinko; Kasemo, Bengt; Tanaka, Junzo

2010-08-01

The repeatability of the adsorption and removal of fibrinogen and fetal bovine serum on hydroxyapatite (HAp) nanocrystal sensors was investigated by Fourier transform infrared (FTIR) spectroscopy and quartz crystal microbalance with dissipation (QCM-D) monitoring technique. The HAp nanocrystals were coated on a gold-coated quartz sensor by electrophoretic deposition. Proteins adsorbed on the HAp sensors were removed by (i) ammonia/hydrogen peroxide mixture (APM), (ii) ultraviolet light (UV), (iii) UV/APM, (iv) APM/UV and (v) sodium dodecyl sulfate (SDS) treatments. FTIR spectra of the reused surfaces revealed that the APM and SDS treatments left peptide fragments or the proteins adsorbed on the surfaces, whereas the other methods successfully removed the proteins. The QCM-D measurements indicated that in the removal treatments, fibrinogen was slowly adsorbed in the first cycle because of the change in surface wettability revealed by contact angle measurements. The SDS treatment was not effective in removing proteins. The APM or UV treatment decreased the frequency shifts for the reused HAp sensors. The UV/APM treatment did not induce the frequency shifts but decreased the dissipation shifts. Therefore, we conclude that the APM/UV treatment is the most useful method for reproducing protein adsorption behavior on HAp sensors.

Reusable hydroxyapatite nanocrystal sensors for protein adsorption

NASA Astrophysics Data System (ADS)

Tagaya, Motohiro; Ikoma, Toshiyuki; Hanagata, Nobutaka; Chakarov, Dinko; Kasemo, Bengt; Tanaka, Junzo

2010-08-01

The repeatability of the adsorption and removal of fibrinogen and fetal bovine serum on hydroxyapatite (HAp) nanocrystal sensors was investigated by Fourier transform infrared (FTIR) spectroscopy and quartz crystal microbalance with dissipation (QCM-D) monitoring technique. The HAp nanocrystals were coated on a gold-coated quartz sensor by electrophoretic deposition. Proteins adsorbed on the HAp sensors were removed by (i) ammonia/hydrogen peroxide mixture (APM), (ii) ultraviolet light (UV), (iii) UV/APM, (iv) APM/UV and (v) sodium dodecyl sulfate (SDS) treatments. FTIR spectra of the reused surfaces revealed that the APM and SDS treatments left peptide fragments or the proteins adsorbed on the surfaces, whereas the other methods successfully removed the proteins. The QCM-D measurements indicated that in the removal treatments, fibrinogen was slowly adsorbed in the first cycle because of the change in surface wettability revealed by contact angle measurements. The SDS treatment was not effective in removing proteins. The APM or UV treatment decreased the frequency shifts for the reused HAp sensors. The UV/APM treatment did not induce the frequency shifts but decreased the dissipation shifts. Therefore, we conclude that the APM/UV treatment is the most useful method for reproducing protein adsorption behavior on HAp sensors.

Characterization of ultraviolet light cured polydimethylsiloxane films for low-voltage, dielectric elastomer actuators

NASA Astrophysics Data System (ADS)

Töpper, Tino; Wohlfender, Fabian; Weiss, Florian; Osmani, Bekim; Müller, Bert

2016-04-01

The reduction the operation voltage has been the key challenge to realize of dielectric elastomer actuators (DEA) for many years - especially for the application fields of robotics, lens systems, haptics and future medical implants. Contrary to the approach of manipulating the dielectric properties of the electrically activated polymer (EAP), we intend to realize low-voltage operation by reducing the polymer thickness to the range of a few hundred nanometers. A study recently published presents molecular beam deposition to reliably grow nanometer-thick polydimethylsiloxane (PDMS) films. The curing of PDMS is realized using ultraviolet (UV) radiation with wavelengths from 180 to 400 nm radicalizing the functional side and end groups. The understanding of the mechanical properties of sub-micrometer-thin PDMS films is crucial to optimize DEAs actuation efficiency. The elastic modulus of UV-cured spin-coated films is measured by nano-indentation using an atomic force microscope (AFM) according to the Hertzian contact mechanics model. These investigations show a reduced elastic modulus with increased indentation depth. A model with a skin-like SiO2 surface with corresponding elastic modulus of (2.29 +/- 0.31) MPa and a bulk modulus of cross-linked PDMS with corresponding elastic modulus of (87 +/- 7) kPa is proposed. The surface morphology is observed with AFM and 3D laser microscopy. Wrinkled surface microstructures on UV-cured PDMS films occur for film thicknesses above (510 +/- 30) nm with an UV-irradiation density of 7.2 10-4 J cm-2 nm-1 at a wavelength of 190 nm.

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

NASA Astrophysics Data System (ADS)

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.

Research on the calibration of ultraviolet energy meters

NASA Astrophysics Data System (ADS)

Lin, Fangsheng; Yin, Dejin; Li, Tiecheng; Lai, Lei; Xia, Ming

2016-10-01

Ultraviolet (UV) radiation is a kind of non-lighting radiation with the wavelength range from 100nm to 400nm. Ultraviolet irradiance meters are now widely used in many areas. However, as the development of science and technology, especially in the field of light-curing industry, there are more and more UV energy meters or UV-integrators need to be measured. Because the structure, wavelength band and measured power intensity of UV energy meters are different from traditional UV irradiance meters, it is important for us to take research on the calibration. With reference to JJG879-2002, we SIMT have independently developed the UV energy calibration device and the standard of operation and experimental methods for UV energy calibration in detail. In the calibration process of UV energy meter, many influencing factors will affect the final results, including different UVA-band UV light sources, different spectral response for different brands of UV energy meters, instability and no uniformity of UV light source and temperature. Therefore we need to take all of these factors into consideration to improve accuracy in UV energy calibration.

Plant response to solar ultraviolet radiation

NASA Technical Reports Server (NTRS)

Caldwell, M. M.

1981-01-01

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

Design, fabrication, and measurement of two silicon-based ultraviolet and blue-extended photodiodes

NASA Astrophysics Data System (ADS)

Chen, Changping; Wang, Han; Jiang, Zhenyu; Jin, Xiangliang; Luo, Jun

2014-12-01

Two silicon-based ultraviolet (UV) and blue-extended photodiodes are presented, which were fabricated for light detection in the ultraviolet/blue spectral range. Stripe-shaped and octagon-ring-shaped structures were designed to verify parameters of the UV-responsivity, UV-selectivity, breakdown voltage, and response time. The ultra-shallow lateral pn junction had been successfully realized in a standard 0.5-μm complementary metal oxide semiconductor (CMOS) process to enlarge the pn junction area, enhance the absorption of UV light, and improve the responsivity and quantum efficiency. The test results illustrated that the stripe-shaped structure has the lower breakdown voltage, higher UV-responsicity, and higher UV-selectivity. But the octagon-ring-shaped structure has the lower dark current. The response time of both structures was almost the same.

ULTRAVIOLET DISINFECTION OF A SECONDARY EFFLUENT: MEASUREMENT OF DOSE AND EFFECTS OF FILTRATION

EPA Science Inventory

Ultraviolet (UV) disinfection of wastewater secondary effluent was investigated in a two-phase study to develop methods for measuring UV dose and to determine the effects of filtration on UV disinfection. The first phase of this study involved a pilot plant study comparing filtra...

Some Thoughts on Teaching about Ultraviolet Radiation

ERIC Educational Resources Information Center

Thumm, Walter

1975-01-01

Describes the major obstacles in the study of ultraviolet radiation (UV). Presents the beneficial aspects of UV such as vitamin O production, sterilization, clinical treatment of diseases and wounds, and the marking of patients for radiotherapy. Warns of the dangers of UV exposure such as skin cancer and early aging. (GS)

Comparison of two whole-room ultraviolet irradiation systems for enhanced disinfection of contaminated hospital patient rooms.

PubMed

Ali, S; Yui, S; Muzslay, M; Wilson, A P R

2017-10-01

Ultraviolet (UV) light decontamination systems are being used increasingly to supplement terminal disinfection of patient rooms. However, efficacy may not be consistent in the presence of soil, especially against Clostridium difficile spores. To demonstrate in-use efficacy of two whole-room UV decontamination systems against three hospital pathogens with and without soil. For each system, six patient rooms were decontaminated with UV irradiation (enhanced disinfection) following manual terminal cleaning. Total aerobic colony counts of surface contamination were determined by spot-sampling 15 environmental sites before and after terminal disinfection and after UV irradiation. Efficacy against biological indicator coupons (stainless-steel discs) was performed for each system using test bacteria (10 6  cfu EMRSA-15 variant A, carbapenemase-producing Klebsiella pneumoniae) or spores (10 5  cfu C. difficile 027), incorporating low soiling [0.03% bovine serum albumin (BSA)], heavy soiling (10% BSA) or synthetic faeces (C. difficile only) placed at five locations in the room. UV disinfection eliminated contamination after terminal cleaning in 8/14 (57%) and 11/14 (79%) sites. Both systems demonstrated 4-5 log 10 reductions in meticillin-resistant Staphylococcus aureus and K. pneumoniae at low soiling. Lower and more variable log 10 reductions were achieved when heavy soiling was present. Between 0.1 and 4.8 log 10 reductions in C. difficile spores were achieved with low but not heavy soil challenge. Terminal disinfection should be performed on all surfaces prior to UV decontamination. In-house validation studies should be considered to ensure optimal positioning in each room layout and sufficient cycle duration to eliminate target pathogens. Copyright © 2017 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

Potential of ultraviolet wide-field imaging and multiphoton microscopy for analysis of dehydroergosterol in cellular membranes.

PubMed

Wüstner, Daniel; Brewer, Jonathan R; Bagatolli, Luis; Sage, Daniel

2011-01-01

Dehydroergosterol (DHE) is an intrinsically fluorescent sterol with absorption/emission in the ultraviolet (UV) region and biophysical properties similar to those of cholesterol. We compared the potential of UV-sensitive low-light-level wide-field (UV-WF) imaging with that of multiphoton (MP) excitation microscopy to monitor DHE in living cells. Significantly reduced photobleaching in MP microscopy of DHE enabled us to acquire three-dimensional z-stacks of DHE-stained cells and to obtain high-resolution maps of DHE in surface ruffles, nanotubes, and the apical membrane of epithelial cells. We found that the lateral resolution of MP microscopy is ∼1.5-fold higher than that of UV-WF deconvolution microscopy, allowing for improved spatiotemporal analysis of plasma membrane sterol distribution. Surface intensity patterns of DHE with a diameter of 0.2 μm persisting over several minutes could be resolved by MP time-lapse microscopy. Diffusion coefficients of 0.25-μm-diameter endocytic vesicles containing DHE were determined by MP spatiotemporal image correlation spectroscopy. The requirement of extremely high laser power for visualization of DHE by MP microscopy made this method less potent for multicolor applications with organelle markers like green fluorescent protein-tagged proteins. The signal-to-noise ratio obtainable by UV-WF imaging could be significantly improved by pixelwise bleach rate fitting and calculation of an amplitude image from the decay model and by frame averaging after pixelwise bleaching correction of the image stacks. We conclude that UV-WF imaging and MP microscopy of DHE provide complementary information regarding membrane distribution and intracellular targeting of sterols. © 2010 Wiley-Liss, Inc.

TOMS UV Algorithm: Problems and Enhancements. 2

NASA Technical Reports Server (NTRS)

Krotkov, Nickolay; Herman, Jay; Bhartia, P. K.; Seftor, Colin; Arola, Antti; Kaurola, Jussi; Kroskinen, Lasse; Kalliskota, S.; Taalas, Petteri; Geogdzhaev, I.

2002-01-01

Satellite instruments provide global maps of surface ultraviolet (UV) irradiance by combining backscattered radiance measurements with radiative transfer models. The models are limited by uncertainties in input parameters of the atmosphere and the surface. We evaluate the effects of possible enhancements of the current Total Ozone Mapping Spectrometer (TOMS) surface UV irradiance algorithm focusing on effects of diurnal variation of cloudiness and improved treatment of snow/ice. The emphasis is on comparison between the results of the current (version 1) TOMS UV algorithm and each of the changes proposed. We evaluate different approaches for improved treatment of pixel average cloud attenuation, with and without snow/ice on the ground. In addition to treating clouds based only on the measurements at the local time of the TOMS observations, the results from other satellites and weather assimilation models can be used to estimate attenuation of the incident UV irradiance throughout the day. A new method is proposed to obtain a more realistic treatment of snow covered terrain. The method is based on a statistical relation between UV reflectivity and snow depth. The new method reduced the bias between the TOMS UV estimations and ground-based UV measurements for snow periods. The improved (version 2) algorithm will be applied to re-process the existing TOMS UV data record (since 1978) and to the future satellite sensors (e.g., Quik/TOMS, GOME, OMI on EOS/Aura and Triana/EPIC).

Dependence of nanomechanical modification of polymers on plasma-induced cross-linking

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

Tajima, S.; Komvopoulos, K.

2007-01-01

The nanomechanical properties of low-density polyethylene (LDPE) modified by inductively coupled, radio-frequency Ar plasma were investigated by surface force microscopy. The polymer surface was modified under plasma conditions of different ion energy fluences and radiation intensities obtained by varying the sample distance from the plasma power source. Nanoindentation results of the surface stiffness versus maximum penetration depth did not reveal discernible differences between untreated and plasma-treated LDPE, presumably due to the small thickness of the modified surface layer that resulted in a substrate effect. On the contrary, nanoscratching experiments demonstrated a significant increase in the surface shear resistance of plasma-modifiedmore » LDPE due to chain cross-linking. These experiments revealed an enhancement of cross-linking with increasing ion energy fluence and radiation intensity, and a tip size effect on the friction force and dominant friction mechanisms (adhesion, plowing, and microcutting). In addition, LDPE samples with a LiF crystal shield were exposed to identical plasma conditions to determine the role of vacuum ultraviolet (VUV) and ultraviolet (UV) radiation in the cross-linking process. The cross-linked layer of plasma-treated LDPE exhibited much higher shear strength than that of VUV/UV-treated LDPE. Plasma-induced surface modification of the nanomechanical properties of LDPE is interpreted in the context of molecular models of the untreated and cross-linked polymer surfaces derived from experimental findings.« less

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

NASA Astrophysics Data System (ADS)

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.

Effects of storage medium and UV photofunctionalization on time-related changes of titanium surface characteristics and biocompatibility.

PubMed

Shen, Jian-Wei; Chen, Yun; Yang, Guo-Li; Wang, Xiao-Xiang; He, Fu-Ming; Wang, Hui-Ming

2016-07-01

Storage in aqueous solution and ultraviolet (UV) photofunctionalization are two applicable methods to overcome the biological aging and increase the bioactivity of titanium. As information regarding the combined effects of storage medium and UV photofunctionalization has never been found in published literatures, this study focused on whether appropriate storage methods and UV photofunctionalization have synergistic effects on the biological properties of aged titanium surfaces. Titanium plates and discs were sandblasted and acid etched and then further prepared in five different modes as using different storage mediums (air or dH2 O) for 4 weeks and then with or without UV treatment. The surface characteristics were evaluated with scanning electron microscopy, contact angle measurements, and X-ray photoelectron spectroscopy. MC3T3-E1 cells were cultured on the surfaces, and cellular morphology, proliferation, alkaline phosphatase activity, and osteocalcin release were evaluated. The results showed that nanostructures were observed on water-stored titanium surfaces with a size of about 15 × 20 nm(2) . UV treatment was effective to remove the hydrocarbon contamination on titanium surfaces stored in either air or water. UV photofunctionalization further enhanced the already increased bioactivity of modSLA on initial cell attachment, proliferation, alkaline phosphatase activity, and osteocalcin release. Overall, UV photofunctionalization was effective in further enhancing the already increased bioactivity by using dH2 O as storage medium, and the effect of UV treatment was much more overwhelming than that of the storage medium. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 932-940, 2016. © 2015 Wiley Periodicals, Inc.

Distribution of boreal toad populations in relation to estimated UV-B dose in Glacier National Park, Montana, USA

USGS Publications Warehouse

Hossack, B.R.; Diamond, S.A.; Corn, P.S.

2006-01-01

A recent increase in ultraviolet B radiation is one hypothesis advanced to explain suspected or documented declines of the boreal toad (Bufo boreas Baird and Girard, 1852) across much of the western USA, where some experiments have shown ambient UV-B can reduce embryo survival. We examined B. boreas occupancy relative to daily UV-B dose at 172 potential breeding sites in Glacier National Park, Montana, to assess whether UV-B limits the distribution of toads. Dose estimates were based on ground-level UV-B data and the effects of elevation, local topographic and vegetative features, and attenuation in the water column. We also examined temporal trends in surface UV-B and spring snowpack to determine whether populations are likely to have experienced increased UV-B exposure in recent decades. We found no support for the hypothesis that UV-B limits the distribution of populations in the park, even when we analyzed high-elevation ponds separately. Instead, toads were more likely to breed in water bodies with higher estimated UV-B doses. The lack of a detectable trend in surface UV-B since 1979, combined with earlier snow melt in the region and increasing forest density at high elevations, suggests B. boreas embryos and larvae likely have not experienced increased UV-B.

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

NASA Astrophysics Data System (ADS)

Popov, Dmitri; Jones, Jeffrey; Maliev, Slava

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

Use of image analysis to estimate anthocyanin and UV-excited fluorescent phenolic compound levels in strawberry fruit

PubMed Central

Yoshioka, Yosuke; Nakayama, Masayoshi; Noguchi, Yuji; Horie, Hideki

2013-01-01

Strawberry is rich in anthocyanins, which are responsible for the red color, and contains several colorless phenolic compounds. Among the colorless phenolic compounds, some, such as hydroxycinammic acid derivatives, emit blue-green fluorescence when excited with ultraviolet (UV) light. Here, we investigated the effectiveness of image analyses for estimating the levels of anthocyanins and UV-excited fluorescent phenolic compounds in fruit. The fruit skin and cut surface of 12 cultivars were photographed under visible and UV light conditions; colors were evaluated based on the color components of images. The levels of anthocyanins and UV-excited fluorescent compounds in each fruit were also evaluated by spectrophotometric and high performance liquid chromatography (HPLC) analyses, respectively and relationships between these levels and the image data were investigated. Red depth of the fruits differed greatly among the cultivars and anthocyanin content was well estimated based on the color values of the cut surface images. Strong UV-excited fluorescence was observed on the cut surfaces of several cultivars, and the grayscale values of the UV-excited fluorescence images were markedly correlated with the levels of those fluorescent compounds as evaluated by HPLC analysis. These results indicate that image analyses can select promising genotypes rich in anthocyanins and fluorescent phenolic compounds. PMID:23853516

Thin film optical coatings for the ultraviolet spectral region

NASA Astrophysics Data System (ADS)

Torchio, P.; Albrand, G.; Alvisi, M.; Amra, C.; Rauf, H.; Cousin, B.; Otrio, G.

2017-11-01

The applications and innovations related to the ultraviolet field are today in strong growth. To satisfy these developments which go from biomedical to the large equipment like the Storage Ring Free Electron Laser, it is crucial to control with an extreme precision the optical performances, in using the substrates and the thin film materials impossible to circumvent in this spectral range. In particular, the reduction of the losses by electromagnetic diffusion, Joule effect absorption, or the behavior under UV luminous flows of power, resistance to surrounding particulate flows... become top priority which concerns a broad European and international community. Our laboratory has the theoretical, experimental and technological tools to design and fabricate numerous multilayer coatings with desirable optical properties in the visible and infrared spectral ranges. We have extended our expertise to the ultraviolet. We present here some results on high reflectivity multidielectric mirrors towards 250 nm in wavelength, produced by Ion Plating Deposition. The latter technique allows us to obtain surface treatments with low absorption and high resistance. We give in this study the UV transparent materials and the manufacturing technology which have been the best suited to meet requirements. Single UV layers were deposited and characterized. HfO2/SiO2 mirrors with a reflectance higher than 99% at 300 nm were obtained. Optical and non-optical characterizations such as UV spectrophotometric measurements, X-Ray Diffraction spectra, Scanning Electron Microscope and Atomic Force Microscope images were performed

Pre-vitamin D effective ultraviolet transmission through clothing during simulated wear.

PubMed

Parisi, A V; Wilson, C A

2005-12-01

Clothing is an important protective layer used to reduce ultraviolet (UV) exposures to the skin surface. However, not all UV exposure is linked to detrimental health effects with some exposure to UVB wavelengths below 316 nm required for the synthesis of pre-vitamin D(3). The aim of the current research was to investigate the effect of fabric type, color, fit, and wetness on the transmission of pre-vitamin D(3) effective UV through garments during simulated wear, in a high UV exposure environment. Dosimeters fabricated from polysulfone film were positioned at eight selected body sites on the skin surface and clothing surface of identically designed, loose and fitted, black and white T-shirts made up in two knitted fabric types and tested when both dry and when drying after initial wetting (n=3 replicates). The T-shirts were placed on manikins set to simulate humans in the sun between 09:30 and 12:30 Eastern Standard Time during the Southern Hemisphere summer period. The post-exposure absorbance was measured and the dosimeters were calibrated for biologically effective UV for pre-vitamin D(3) synthesis with a UV spectroradiometer. The effect of fit, fabric type, color, and wetness on pre-vitamin D(3) effective UV transmission during simulated wear was assessed. Irradiances varied among body sites with the highest erythemal exposures to a horizontal plane over the 3 h period reaching approximately 14.5 minimal erythema dose (MED) while the highest exposure under the garment was 0.22 MED which may not be above the threshold for pre-vitamin D(3) synthesis for the time period investigated. Fabric and fit were the main variables affecting transmission of pre-vitamin D(3) effective UV. Some interactions were identified between the fabric color and wetness and between fabric type and color; however, while significantly modifying transmission these effects were small. Transmission of pre-vitamin D(3) effective UV occurred through the high UPF knitted fabrics investigated. However, the length of exposure will influence whether the irradiances are sufficient to be above the threshold for pre-vitamin D(3) synthesis. The main effect on transmission of pre-vitamin D(3) effective UV was the fit of the T-shirt and its fabric type (probably structure) rather than color or degree of wetness.

Study on performances of colorless and transparent shape memory polyimide film in space thermal cycling, atomic oxygen and ultraviolet irradiation environments

NASA Astrophysics Data System (ADS)

Gao, Hui; Lan, Xin; Liu, Liwu; Xiao, Xinli; Liu, Yanju; Leng, Jinsong

2017-09-01

Shape memory polymers with high glass transition temperature (HSMPs) and HSMP-based deployable structures and devices, which can bear harsh operation conditions for durable applications, have attracted more and more interest in recent years. In this article, colorless and transparent shape memory polyimide (SMCTPI) films were subjected to simulated vacuum thermal cycling, atomic oxygen (AO) and ultraviolet (UV) irradiation environments up to 600 h, 556 h and 600 h for accelerated irradiation. The glass transition temperature (Tg) determined by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) had no obvious changes after being irradiated by varying amounts of thermal cycling, AO and UV irradiation dose. After being irradiated by 50 thermal cycles, 10 × 1021 atoms cm-2 AO irradiation and 3000 ESH UV irradiation, shape recovery behaviors of SMCTPI films also had no obvious damage even if they experienced 30 shape memory cycles, while the surface morphologies and optical properties were seriously destroyed by AO irradiation, as compared with thermal cycling and UV irradiation. The tensile strength could separately maintain 122 MPa, 120 MPa and 70 MPa after 50 thermal cycles, 10 × 1021 atoms cm-2 AO irradiation and 3000 ESH UV irradiation, which shows great potential for use in aerospace structures and devices.

The Diffuse Radiation Field at High Galactic Latitudes

NASA Astrophysics Data System (ADS)

Akshaya, M. S.; Murthy, Jayant; Ravichandran, S.; Henry, R. C.; Overduin, James

2018-05-01

We have used GALEX observations of the north and south Galactic poles to study the diffuse ultraviolet background at locations where the Galactic light is expected to be at a minimum. We find offsets of 230–290 photon units in the far-UV (1531 Å) and 480–580 photon units in the near-UV (2361 Å). Of this, approximately 120 photon units can be ascribed to dust-scattered light and another 110 photon units (190 in the near-UV) to extragalactic radiation. The remaining radiation is, as yet, unidentified and amounts to 120–180 photon units in the far-UV and 300–400 photon units in the near-UV. We find that molecular hydrogen fluorescence contributes to the far-UV when the 100 μm surface brightness is greater than 1.08 MJy sr‑1.

Testing Of An Ultraviolet (UV)-Transparent Polymer-Based Passive Sampler for Rapid, Ultra-Low-Cost EDC Screening Applications

EPA Science Inventory

A new passive sampling method with rapid low-cost spectral detection has recently been developed. The method makes use of an ultraviolet (UV)-transparent polymer which serves as both a concentrator for dissolved compounds, and an optical cell for UV spectral detection. Because ...

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

PubMed Central

Corrêa, Marcelo de Paula

2015-01-01

The beneficial and harmful effects of human exposure to solar ultraviolet radiation (UV-R) are topics that arouse great interest not only among physicians and scientists, but also the general public and the media. Currently, discussions on vitamin D synthesis (beneficial effect) are confronted with the high and growing number of new cases of non-melanoma skin cancer and other diseases of the skin and eyes (harmful effect) diagnosed each year in Brazil. However, the lack of scientific knowledge on the UV-R in Brazil and South America leads to adoption of protective measures based on studies conducted in Europe and USA, where the amounts of UV-R available at surface and the sun-exposure habits and characteristics of the population are significantly different from those observed in Brazil. In order to circumvent this problem, the Brazilian Society of Dermatology recently published the Brazilian Consensus of Photoprotection based on recent studies performed locally. The main goal of this article is to provide detailed educational information on the main properties and characteristics of UV-R and UV index in a simple language. It also provides: a) a summary of UV-R measurements recently performed in Brazil; b) a comparison with those performed in Europe; and, c) an evaluation to further clarify the assessment of potential harm and health effects owing to chronic exposures. PMID:26131858

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

PubMed

Corrêa, Marcelo de Paula

2015-01-01

The beneficial and harmful effects of human exposure to solar ultraviolet radiation (UV-R) are topics that arouse great interest not only among physicians and scientists, but also the general public and the media. Currently, discussions on vitamin D synthesis (beneficial effect) are confronted with the high and growing number of new cases of non-melanoma skin cancer and other diseases of the skin and eyes (harmful effect) diagnosed each year in Brazil. However, the lack of scientific knowledge on the UV-R in Brazil and South America leads to adoption of protective measures based on studies conducted in Europe and USA, where the amounts of UV-R available at surface and the sun-exposure habits and characteristics of the population are significantly different from those observed in Brazil. In order to circumvent this problem, the Brazilian Society of Dermatology recently published the Brazilian Consensus of Photoprotection based on recent studies performed locally. The main goal of this article is to provide detailed educational information on the main properties and characteristics of UV-R and UV index in a simple language. It also provides: a) a summary of UV-R measurements recently performed in Brazil; b) a comparison with those performed in Europe; and, c) an evaluation to further clarify the assessment of potential harm and health effects owing to chronic exposures.

Effectiveness of eye drops protective against ultraviolet radiation.

PubMed

Daxer, A; Blumthaler, M; Schreder, J; Ettl, A

1998-01-01

To test the effectiveness of commercially available ultraviolet (UV)-protective eye drops (8-hydroxy-1-methylchinolinium methylsulphate) which are recommended for protection against both solar and artificial UV radiation. The spectral transmission in the wavelength range from 250 to 500 nm was investigated in 1-nm steps using a high-resolution double monochromator with holographic gratings of 2,400 lines/mm and a 1,000-watt halogen lamp as light source. The transmission spectrum was measured for different values of the layer thickness. The transmission of a liquid layer of about 10 microns, which corresponds to the thickness of the human tear film, shows a cut-off at 290 nm with a transmission of about 25-50% at shorter wavelengths. For wavelengths longer than 290 nm the transmission is higher than 90%. The threshold time ratio for keratitis formation with and without eye drops is above 0.93 considering solar radiation on the earth's surface and above 0.65 considering radiation from arc-welding, respectively. The transmission spectrum of the eye drops under realistic conditions does not show a protective effect against solar UV radiation. However, there exists reduction of UVC radiation in the spectral range typical of artificial UV sources such as arc-welding. We cannot recommend the application of these eye drops as an UV-protective aid against eye damage by solar UV radiation.

Photosynthetic benefits of ultraviolet-A to Pimelea ligustrina, a woody shrub of sub-alpine Australia.

PubMed

Turnbull, Tarryn L; Barlow, Alexandra M; Adams, Mark A

2013-10-01

The definition of photosynthetically active radiation (Q) as the visible waveband (λ 400-700 nm) is a core assumption of much of modern plant biology and global models of carbon and water fluxes. On the other hand, much research has focused on potential mutation and damage to leaves caused by ultraviolet (UV) radiation (280-400 nm), and anatomical and physiological adaptations that help avoid such damage. Even so, plant responses to UV-A are poorly described and, until now, photosynthetic utilization of UV-A has not been elucidated under full light conditions in the field. We found that the UV-A content of sunlight increased photosynthetic rates in situ by 12% in Pimelea ligustrina Labill., a common and indigenous woody shrub of alpine ecosystems of the Southern Hemisphere. Compared to companion shrubs, UV-A-induced photosynthesis in P. ligustrina resulted from reduced physical and chemical capacities to screen UV-A at the leaf surface (illustrated by a lack of cuticle and reduced phenol index) and the resulting ability of UV-A to excite chlorophyll (Chl) a directly, and via energy provided by the carotenoid lutein. A screening of 55 additional sub-alpine species showed that 47% of the plant taxa also display Chl a fluorescence under UV-A. If Chl a fluorescence indicates potential for photosynthetic gain, continued exclusion of UV-A from definitions of Q in this ecosystem could result in underestimates of measured and modeled rates of photosynthesis and miscalculation of potential for carbon sequestration. We suggest that carbon gain for alpine environs across the globe could be similarly underestimated given that UV-A radiation increases with altitude and that the frequently dominant herb and grass life-forms often transmit UV-A through the epidermis.

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

NASA Technical Reports Server (NTRS)

Robberecht, R.; Caldwell, M. M.

1981-01-01

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

The effects of ultraviolet-B radiation on the toxicity of fire-fighting chemicals

USGS Publications Warehouse

Calfee, R.D.; Little, E.E.

2003-01-01

The interactive effects of ultraviolet (UV) and fire-retardant chemicals were evaluated by exposing rainbow trout (Oncorhyncus mykiss) juveniles and tadpoles of southern leopard frogs (Rana sphenocephala) to six fire-retardant formulations with and without sodium ferrocyanide (yellow prussiate of soda [YPS]) and to YPS alone under three simulated UV light treatments. Yellow prussiate of soda is used as a corrosion inhibitor in some of the fire-retardant chemical formulations. The underwater UV intensities measured were about 2 to 10% of surface irradiance measured in various aquatic habitats and were within tolerance limits for the species tested. Mortality of trout and tadpoles exposed to Fire-Trol?? GTS-R, Fire-Trol 300-F, Fire-Trol LCA-R, and Fire-Trol LCA-F was significantly increased in the presence of UV radiation when YPS was present in the formulation. The boreal toad (Bufo boreas), listed as endangered by the state of Colorado (USA), and southern leopard frog were similar in their sensitivity to these chemicals. Photoenhancement of fire-retardant chemicals can occur in a range of aquatic habitats and may be of concern even when optical clarity of water is low; however, other habitat characteristics can also reduce fire retardant toxicity.

Multi-angle ZnO microstructures grown on Ag nanorods array for plasmon-enhanced near-UV-blue light emitter

NASA Astrophysics Data System (ADS)

Pal, Anil Kumar; Bharathi Mohan, D.

2017-10-01

Metal enhanced ultraviolet light emission has been explored in ZnO/Ag hybrid structures prepared by hydrothermal growth of multi-angled ZnO nanorods on slanted Ag nanorods array fabricated by the thermal evaporation technique. Slanted Ag nanorods are realized to be the stacking of non-spherical Ag nanoparticles, resulting in asymmetric surface plasmon resonance spectra. The surface roughness of Ag nanorod array films significantly influences the growth mechanism of ZnO nanorods, leading to the formation of multi-angled ZnO microflowers. ZnO/Ag hybrid structures facilitate the interfacial charge transfer from Ag to ZnO with the realization of negative shift in binding energy of Ag 3d orbitals by ˜0.8 eV. These high quality ZnO nanorods in ZnO/Ag hybrid nanostructures exhibit strong ultraviolet emission in the 383-396 nm region without broad deep level emission, which can be explained by a suitable band diagram. The metal enhanced photoluminescence is witnessed mainly due to interfacial charge transfer with its dependence on surface roughness of bottom layer Ag nanorods, number density of ZnO nanorods and diversity in the interfacial area between Ag and ZnO nanorods. The existence of strong ultraviolet light with minor blue light emission and appearance of CIE shade in strong violet-blue region by ZnO/Ag hybrid structures depict exciting possibilities towards near UV-blue light emitting devices.

Multi-angle ZnO microstructures grown on Ag nanorods array for plasmon-enhanced near-UV-blue light emitter.

PubMed

Pal, Anil Kumar; Mohan, D Bharathi

2017-10-13

Metal enhanced ultraviolet light emission has been explored in ZnO/Ag hybrid structures prepared by hydrothermal growth of multi-angled ZnO nanorods on slanted Ag nanorods array fabricated by the thermal evaporation technique. Slanted Ag nanorods are realized to be the stacking of non-spherical Ag nanoparticles, resulting in asymmetric surface plasmon resonance spectra. The surface roughness of Ag nanorod array films significantly influences the growth mechanism of ZnO nanorods, leading to the formation of multi-angled ZnO microflowers. ZnO/Ag hybrid structures facilitate the interfacial charge transfer from Ag to ZnO with the realization of negative shift in binding energy of Ag 3d orbitals by ∼0.8 eV. These high quality ZnO nanorods in ZnO/Ag hybrid nanostructures exhibit strong ultraviolet emission in the 383-396 nm region without broad deep level emission, which can be explained by a suitable band diagram. The metal enhanced photoluminescence is witnessed mainly due to interfacial charge transfer with its dependence on surface roughness of bottom layer Ag nanorods, number density of ZnO nanorods and diversity in the interfacial area between Ag and ZnO nanorods. The existence of strong ultraviolet light with minor blue light emission and appearance of CIE shade in strong violet-blue region by ZnO/Ag hybrid structures depict exciting possibilities towards near UV-blue light emitting devices.

Dynamic Processes in Be Star Atmospheres.. 6; Simultaneous X-Ray, Ultraviolet, and Optical Variations in lambda Eridani

NASA Technical Reports Server (NTRS)

Smith, Myron A.; Murakami, T.; Ezuka, H.; Anandarao, B. G.; Chakraborty, A.; Corcoran, M. F.; Hirata, R.

1995-01-01

This report describes a joint X ray/ultraviolet/ground based study of the abnormal Be star lambda Eri which has previously shown evidence of X ray flaring from Rosat observations in 1991. The 1991 flare event caught the astronomical hot star community by surprise because x ray flares have not been observed from other single B-type stars, before or since. Both optical (H-alpha) and UV/Voyager observations provide evidence for transient heating events near the surface of lambda Eri.

Comets in UV

NASA Astrophysics Data System (ADS)

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.

Purification system

NASA Technical Reports Server (NTRS)

Flanagan, David T. (Inventor); Gibbons, Randall E. (Inventor)

1992-01-01

A system for prolonging the life of a granulated activated charcoal (GAC) water treatment device is disclosed in which an ultraviolet light transparent material is used to constrain water to flow over carbon surfaces. It is configured to receive maximum flux from a UV radiation source for the purpose of preventing microbial proliferation on the carbon surfaces; oxidizing organic contaminants adsorbed from the water onto the carbon surfaces and from biodegradation of adsorbed microbial forms; disinfecting water; and oxidizing organic contaminants in the water.

Influence of surface sealing on color stability and roughness of composite submitted to ultraviolet-accelerated aging.

PubMed

Catelan, Anderson; Suzuki, Thaís Yumi Umeda; Becker, Francisco; Briso, André Luiz Fraga; Dos Santos, Paulo Henrique

2017-05-01

In the present study, we evaluated the influence of surface sealing on color stability and surface roughness of a composite resin after accelerated artificial aging. Thirty-two specimens of a composite were prepared. After 24 h, the specimens were polished and divided into four groups (n = 8), according to the surface sealant used, including the control, which had no sealant application. Baseline color was measured according to the CIELab system using a reflection spectrophotometer. Surface roughness was determined using a profilometer with a cut-off of 0.25 mm. After these tests, specimens were aged for 252 h in an ultraviolet (UV)-accelerated aging chamber. Color stability was determined by difference between coordinates obtained before and after the aging procedure. Data of color change and roughness were evaluated by anova and Fisher's exact test (α = 0.05). The results showed that the unsealed group had the highest color change compared to other groups (P = 0.0289), and there was no significant difference between groups sealed with surface sealant (P > 0.05). The artificial aging caused an increase in roughness values independent of the experimental group studied (P = 0.0015). The sealed composites showed lower color change after UV aging, but all groups showed clinically-acceptable color change, and only liquid polish decreased roughness. © 2016 John Wiley & Sons Australia, Ltd.

Photoassisted photoluminescence fine-tuning of gold nanodots through free radical-mediated ligand-assembly

NASA Astrophysics Data System (ADS)

Tseng, Yu-Ting; Cherng, Rochelle; Harroun, Scott G.; Yuan, Zhiqin; Lin, Tai-Yuan; Wu, Chien-Wei; Chang, Huan-Tsung; Huang, Chih-Ching

2016-05-01

In this study, we have developed a simple photoassisted ligand assembly to fine-tune the photoluminescence (PL) of (11-mercaptoundecyl)-N,N,N-trimethylammonium bromide-capped gold nanodots (11-MUTAB-Au NDs). The 11-MUTAB-Au NDs (size: ca. 1.8 nm), obtained from the reaction of gold nanoparticles (ca. 3 nm) and 11-MUTAB, exhibited weak, near-infrared (NIR) PL at 700 nm with a quantum yield (QY) of 0.37% upon excitation at 365 nm. The PL QY of the Au NDs increased to 11.43% after reaction with 11-mercaptoundecanoic acid (11-MUA) for 30 min under ultraviolet (UV) light, which was accompanied by a PL wavelength shift to the green region (~520 nm). UV-light irradiation accelerates 11-MUA assembly on the 11-MUTABAu NDs (11-MUA/11-MUTAB-Au NDs) through a radical-mediated reaction. Furthermore, the PL wavelength of the 11-MUA/11-MUTAB-Au NDs can be switched to 640 nm via cysteamine under UV-light irradiation. We propose that the PL of the Au NDs with NIR and visible emissions was originally from the surface thiol-Au complexes and the Au core, respectively. These dramatically different optical properties of the Au NDs were due to variation in the surface ligands, as well as the densities and surface oxidant states of the surface Au atoms/ions. These effects can be controlled by assembling surface thiol ligands and accelerated by UV irradiation.In this study, we have developed a simple photoassisted ligand assembly to fine-tune the photoluminescence (PL) of (11-mercaptoundecyl)-N,N,N-trimethylammonium bromide-capped gold nanodots (11-MUTAB-Au NDs). The 11-MUTAB-Au NDs (size: ca. 1.8 nm), obtained from the reaction of gold nanoparticles (ca. 3 nm) and 11-MUTAB, exhibited weak, near-infrared (NIR) PL at 700 nm with a quantum yield (QY) of 0.37% upon excitation at 365 nm. The PL QY of the Au NDs increased to 11.43% after reaction with 11-mercaptoundecanoic acid (11-MUA) for 30 min under ultraviolet (UV) light, which was accompanied by a PL wavelength shift to the green region (~520 nm). UV-light irradiation accelerates 11-MUA assembly on the 11-MUTABAu NDs (11-MUA/11-MUTAB-Au NDs) through a radical-mediated reaction. Furthermore, the PL wavelength of the 11-MUA/11-MUTAB-Au NDs can be switched to 640 nm via cysteamine under UV-light irradiation. We propose that the PL of the Au NDs with NIR and visible emissions was originally from the surface thiol-Au complexes and the Au core, respectively. These dramatically different optical properties of the Au NDs were due to variation in the surface ligands, as well as the densities and surface oxidant states of the surface Au atoms/ions. These effects can be controlled by assembling surface thiol ligands and accelerated by UV irradiation. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr00795c

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

USGS Publications Warehouse

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

1998-01-01

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

Evaluation of a pulsed xenon ultraviolet light device for isolation room disinfection in a United Kingdom hospital.

PubMed

Hosein, Ian; Madeloso, Rosie; Nagaratnam, Wijayaratnam; Villamaria, Frank; Stock, Eileen; Jinadatha, Chetan

2016-09-01

Pathogen transmission from contaminated surfaces can cause hospital-associated infections. Although pulsed xenon ultraviolet (PX-UV) light devices have been shown to decrease hospital room bioburden in the United States, their effectiveness in United Kingdom (UK) hospitals is less understood. Forty isolation rooms at the Queens Hospital (700 beds) in North London, UK, were sampled for aerobic bacteria after patient discharge, after manual cleaning with a hypochlorous acid-troclosene sodium solution, and after PX-UV disinfection. PX-UV device efficacy on known organisms was tested by exposing inoculated agar plates in a nonpatient care area. Turnaround times for device usage were recorded, and a survey of hospital staff for perceptions of the device was undertaken. After PX-UV disinfection, the bacterial contamination measured in colony forming units (CFU) decreased by 78.4%, a 91% reduction from initial bioburden levels prior to terminal cleaning. PX-UV exposure resulted in a 5-log CFU reduction for multidrug-resistant organisms (MDROs) on spiked plates. The average device turnaround time was 1 hour, with minimal impact on patient throughput. Ward staff were enthusiastic about device deployment, and device operators reported physical comfort in usage. PX-UV use decreased bioburden in patient discharge rooms and on agar plates spiked with MDROs. The implementation of the PX-UV device was well received by hospital cleaning and ward staff, with minimal disruption to patient flow. Copyright © 2016 Association for Professionals in Infection Control and Epidemiology, Inc. All rights reserved.

Inactivation of Uropathogenic Escherichia coli in Ground Chicken Meat Using High Pressure Processing and Gamma Radiation, and in Purge and Chicken Meat Surfaces by Ultraviolet Light.

PubMed

Sommers, Christopher H; Scullen, O J; Sheen, Shiowshuh

2016-01-01

Extraintestinal pathogenic Escherichia coli, including uropathogenic E. coli (UPEC), are common contaminants in poultry meat and may cause urinary tract infections after colonization of the gastrointestinal tract and transfer of contaminated feces to the urethra. Three non-thermal processing technologies used to improve the safety and shelf-life of both human and pet foods include high pressure processing (HPP), ionizing (gamma) radiation (GR), and ultraviolet light (UV-C). Multi-isolate cocktails of UPEC were inoculated into ground chicken which was then treated with HPP (4°C, 0-25 min) at 300, 400, or 500 MPa. HPP D10, the processing conditions needed to inactivate 1 log of UPEC, was 30.6, 8.37, and 4.43 min at 300, 400, and 500 MPa, respectively. When the UPEC was inoculated into ground chicken and gamma irradiated (4 and -20°C) the GR D10 were 0.28 and 0.36 kGy, respectively. The UV-C D10 of UPEC in chicken suspended in exudate and placed on stainless steel and plastic food contact surfaces ranged from 11.4 to 12.9 mJ/cm(2). UV-C inactivated ca. 0.6 log of UPEC on chicken breast meat. These results indicate that existing non-thermal processing technologies such as HPP, GR, and UV-C can significantly reduce UPEC levels in poultry meat or exudate and provide safer poultry products for at-risk consumers.

Ultraviolet emissions from the upper atmospheres of the planets

NASA Technical Reports Server (NTRS)

Moos, H. W.

1981-01-01

Some recent results on planetary upper atmospheres obtained by means of orbiting ultraviolet observatories are reviewed with emphasis on Jupiter and Io torus. Consideration is given to long-term variation in Jovian Ly alpha emission, UV polar auroras on Jupiter, and UV emission from the Io torus. Requirements for UV planetary astronomy are briefly discussed.

An Ultraviolet/Optical Atlas of Bright Galaxies

NASA Astrophysics Data System (ADS)

Marcum, Pamela M.; O'Connell, Robert W.; Fanelli, Michael N.; Cornett, Robert H.; Waller, William H.; Bohlin, Ralph C.; Neff, Susan G.; Roberts, Morton S.; Smith, Andrew M.; Cheng, K.-P.; Collins, Nicholas R.; Hennessy, Gregory S.; Hill, Jesse K.; Hill, Robert S.; Hintzen, Paul; Landsman, Wayne B.; Ohl, Raymond G.; Parise, Ronald A.; Smith, Eric P.; Freedman, Wendy L.; Kuchinski, Leslie E.; Madore, Barry; Angione, Ronald; Palma, Christopher; Talbert, Freddie; Stecher, Theodore P.

2001-02-01

We present wide-field imagery and photometry of 43 selected nearby galaxies of all morphological types at ultraviolet and optical wavelengths. The ultraviolet (UV) images, in two broad bands at 1500 and 2500 Å, were obtained using the Ultraviolet Imaging Telescope (UIT) during the Astro-1 Spacelab mission. The UV images have ~3" resolution, and the comparison sets of ground-based CCD images (in one or more of B, V, R, and Hα) have pixel scales and fields of view closely matching the UV frames. The atlas consists of multiband images and plots of UV/optical surface brightness and color profiles. Other associated parameters, such as integrated photometry and half-light radii, are tabulated. In an appendix, we discuss the sensitivity of different wavebands to a galaxy's star formation history in the form of ``history weighting functions'' and emphasize the importance of UV observations as probes of evolution during the past 10-1000 Myr. We find that UV galaxy morphologies are usually significantly different from visible band morphologies as a consequence of spatially inhomogeneous stellar populations. Differences are quite pronounced for systems in the middle range of Hubble types, Sa through Sc, but less so for ellipticals or late-type disks. Normal ellipticals and large spiral bulges are fainter and more compact in the UV. However, they typically exhibit smooth UV profiles with far-UV/optical color gradients which are larger than any at optical/IR wavelengths. The far-UV light in these cases is probably produced by extreme horizontal branch stars and their descendants in the dominant, low-mass, metal-rich population. The cool stars in the large bulges of Sa and Sb spirals fade in the UV while hot OB stars in their disks brighten, such that their Hubble classifications become significantly later. In the far-UV, early-type spirals often appear as peculiar, ringlike systems. In some spiral disks, UV-bright structures closely outline the spiral pattern; in others, the disks can be much more fragmented and chaotic than at optical wavelengths. Contributions by bright active galactic nuclei (AGNs) to the integrated UV light in our sample range from less than 10% to nearly 100%. A number of systems have unusual UV-bright structures in their inner disks, including rings, compact knots, and starburst nuclei, which could easily dominate the UV light in high-redshift analogs. A significant but variable fraction of the far-UV light in spiral disks is diffuse rather than closely concentrated to star-forming regions. Dust in normal spiral disks does not control UV morphologies, even in some highly inclined disk systems. The heaviest extinction is apparently confined to thin layers and the immediate vicinity of young H II complexes; the UV light emerges from thicker star distributions, regions evacuated of dust by photodestruction or winds, or by virtue of strong dust clumpiness. Only in cases where the dust layers are disturbed does dust appear to be a major factor in UV morphology. The UV-bright plume of M82 indicates that dust scattering of UV photons can be important in some cases. In a companion paper, we discuss far-UV data from the Astro-2 mission and optical comparisons for another 35 galaxies, emphasizing face-on spirals.

UV-POSIT: Web-Based Tools for Rapid and Facile Structural Interpretation of Ultraviolet Photodissociation (UVPD) Mass Spectra

NASA Astrophysics Data System (ADS)

Rosenberg, Jake; Parker, W. Ryan; Cammarata, Michael B.; Brodbelt, Jennifer S.

2018-04-01

UV-POSIT (Ultraviolet Photodissociation Online Structure Interrogation Tools) is a suite of web-based tools designed to facilitate the rapid interpretation of data from native mass spectrometry experiments making use of 193 nm ultraviolet photodissociation (UVPD). The suite includes four separate utilities which assist in the calculation of fragment ion abundances as a function of backbone cleavage sites and sequence position; the localization of charge sites in intact proteins; the calculation of hydrogen elimination propensity for a-type fragment ions; and mass-offset searching of UVPD spectra to identify unknown modifications and assess false positive fragment identifications. UV-POSIT is implemented as a Python/Flask web application hosted at http://uv-posit.cm.utexas.edu. UV-POSIT is available under the MIT license, and the source code is available at https://github.com/jarosenb/UV_POSIT. [Figure not available: see fulltext.

UV-POSIT: Web-Based Tools for Rapid and Facile Structural Interpretation of Ultraviolet Photodissociation (UVPD) Mass Spectra.

PubMed

Rosenberg, Jake; Parker, W Ryan; Cammarata, Michael B; Brodbelt, Jennifer S

2018-06-01

UV-POSIT (Ultraviolet Photodissociation Online Structure Interrogation Tools) is a suite of web-based tools designed to facilitate the rapid interpretation of data from native mass spectrometry experiments making use of 193 nm ultraviolet photodissociation (UVPD). The suite includes four separate utilities which assist in the calculation of fragment ion abundances as a function of backbone cleavage sites and sequence position; the localization of charge sites in intact proteins; the calculation of hydrogen elimination propensity for a-type fragment ions; and mass-offset searching of UVPD spectra to identify unknown modifications and assess false positive fragment identifications. UV-POSIT is implemented as a Python/Flask web application hosted at http://uv-posit.cm.utexas.edu . UV-POSIT is available under the MIT license, and the source code is available at https://github.com/jarosenb/UV_POSIT . Graphical Abstract.

Influence of Desert Dust Intrusions on Ground-based and Satellite Derived Ultraviolet Irradiance in Southeastern Spain

NASA Technical Reports Server (NTRS)

Krotkov, Nickolay A.; Anton, Manuel; Valenzuela, Antonio; Roman, Roberto; Lyamani, Hassan; Arola, Antti; Olmo, Francisco J.; Alados-Arboledas

2012-01-01

The desert dust aerosols strongly affect propagation of solar radiation through the atmosphere, reducing surface irradiance available for photochemistry and photosynthesis. This paper evaluates effects of desert dust on surface UV erythemal irradiance (UVER), as measured by a ground-based broadband UV radiometer and retrieved from the satellite Ozone Monitoring Instrument (OMI) at Granada (southern Spain) from January 2006 to December 2010. The dust effects are characterized by the transmittance ra tio of the measured UVER to the corresponding modeled clear sky value. The transmittance has an exponential dependency on aerosol optical depth (AOD), with minimum values of approximately 0.6 (attenuation of approximately 40%). The OMI UVER algorithm does not account for UV aerosol absorption, which results in overestimation of the ground-based UVER especially during dust episodes with a mean relative difference up to 40%. The application of aerosol absorption post-correction method reduces OMI bias up to approximately 13%. The results highlight great effect of desert dust on the surface UV irradiance in regions like southern Spain, where dust intrusions from Sahara region are very frequent.

Deep UV Native Fluorescence Imaging of Antarctic Cryptoendolithic Communities

NASA Technical Reports Server (NTRS)

Storrie-Lombardi, M. C.; Douglas, S.; Sun, H.; McDonald, G. D.; Bhartia, R.; Nealson, K. H.; Hug, W. F.

2001-01-01

An interdisciplinary team at the Jet Propulsion Laboratory Center for Life Detection has embarked on a project to provide in situ chemical and morphological characterization of Antarctic cryptoendolithic microbial communities. We present here in situ deep ultraviolet (UV) native fluorescence and environmental scanning electron microscopy images transiting 8.5 mm into a sandstone sample from the Antarctic Dry Valleys. The deep ultraviolet imaging system employs 224.3, 248.6, and 325 nm lasers to elicit differential fluorescence and resonance Raman responses from biomolecules and minerals. The 224.3 and 248.6 nm lasers elicit a fluorescence response from the aromatic amino and nucleic acids. Excitation at 325 nm may elicit activity from a variety of biomolecules, but is more likely to elicit mineral fluorescence. The resultant fluorescence images provide in situ chemical and morphological maps of microorganisms and the associated organic matrix. Visible broadband reflectance images provide orientation against the mineral background. Environmental scanning electron micrographs provided detailed morphological information. The technique has made possible the construction of detailed fluorescent maps extending from the surface of an Antarctic sandstone sample to a depth of 8.5 mm. The images detect no evidence of microbial life in the superficial 0.2 mm crustal layer. The black lichen component between 0.3 and 0.5 mm deep absorbs all wavelengths of both laser and broadband illumination. Filamentous deep ultraviolet native fluorescent activity dominates in the white layer between 0.6 mm and 5.0 mm from the surface. These filamentous forms are fungi that continue into the red (iron-rich) region of the sample extending from 5.0 to 8.5 mm. Using differential image subtraction techniques it is possible to identify fungal nuclei. The ultraviolet response is markedly attenuated in this region, apparently from the absorption of ultraviolet light by iron-rich particles coating the filaments. Below 8.5 mm the filamentous morphology of the upper layers gives way to punctate 1-2 micron particles evidencing fluorescent activity following excitation at both deep ultraviolet wavelengths.

Attenuation by clouds of UV radiation for low stratospheric ozone conditions

NASA Astrophysics Data System (ADS)

Orte, Facundo; Wolfram, Elian; Salvador, Jacobo; D'Elia, Raúl; Quiroga, Jonathan; Quel, Eduardo; Mizuno, Akira

2017-02-01

Stratospheric poor ozone air masses related to the polar ozone hole overpass subpolar regions in the Southern Hemisphere during spring and summer seasons, resulting in increases of surface Ultraviolet Index (UVI). The impact of these abnormal increases in the ultraviolet radiation could be overestimated if clouds are not taking into account. The aim of this work is to determine the percentage of cases in which cloudiness attenuates the high UV radiation that would reach the surface in low total ozone column situations and in clear sky hypothetical condition for Río Gallegos, Argentina. For this purpose, we analysed UVI data obtained from a multiband filter radiometer GUV-541 (Biospherical Inc.) installed in the Observatorio Atmosférico de la Patagonia Austral (OAPA-UNIDEF (MINDEF - CONICET)) (51 ° 33' S, 69 ° 19' W), Río Gallegos, since 2005. The database used covers the period 2005-2012 for spring seasons. Measured UVI values are compared with UVI calculated using a parametric UV model proposed by Madronich (2007), which is an approximation for the UVI for clear sky, unpolluted atmosphere and low surface albedo condition, using the total ozone column amount, obtained from the OMI database for our case, and the solar zenith angle. It is observed that ˜76% of the total low ozone amount cases, which would result in high and very high UVI categories for a hypothetical (modeled) clear sky condition, are attenuated by clouds, while 91% of hypothetical extremely high UVI category are also attenuated.

EVALUATION OF A PILOT-SCALE ULTRAVIOLET (UV) LIGHT AND OZONE TREATMENT SYSTEM FOR REMOVAL OF MTBE FROM DRINKING WATER SOURCES

EPA Science Inventory

The U.S. Environmental Protection Agency (EPA) is currently evaluating package plant advanced oxidation process (AOP) systems to treat methyl tertiary butyl ether (MTBE) in drinking water supplies (e.g., surface water, groundwater). MTBE has been identified as a potential carcin...

Testing of a Stacked Core Mirror for UV Applications

NASA Technical Reports Server (NTRS)

Matthews, Gary W.; Kirk, Charles S.; Maffett, Steven P.; Abplanalp, Calvin E.; Stahl, H. Philip; Eng, Ron; Arnold, William R. Sr.

2013-01-01

Advanced Ultraviolet, Optical, Near-Infrared (UVOIR) Mirror Technology Development (AMTD) Testing Summary: (1) Processing of the stacked core mirror converged very quickly using ion figuring. (2) Results show no significant PSD change due to ion figuring in spatial periods smaller than 20mm. (3) Global surface figure limited by mount repeatability

How Are Changing Solar Ultraviolet Radiation and Climate Affecting Light-induced Chemical Processes in Aquatic Environments?

EPA Science Inventory

Changes in the ozone layer over the past three decades have resulted in increases in solar UV-B radiation (280-315 nm) that reach the surface of aquatic environments. These changes have been accompanied by unprecedented changes in temperature and precipitation patterns around the...

A model for choosing an automated ultraviolet-C disinfection system and building a case for the C-suite: Two case reports.

PubMed

Spencer, Maureen; Vignari, Michelle; Bryce, Elizabeth; Johnson, Helen Boehm; Fauerbach, Loretta; Graham, Denise

2017-03-01

Environmental disinfection has become the new frontier in the ongoing battle to reduce the risk of health care-associated infections. Evidence demonstrating the persistent contamination of environmental surfaces despite traditional cleaning and disinfection methods has led to the widespread acceptance that there is both a need for reassessing traditional cleaning protocols and for using secondary disinfection technologies. Ultraviolet-C (UV-C) disinfection is one type of no-touch technology shown to be a successful adjunct to manual cleaning in reducing environmental bioburden. The dilemma for the infection preventionist, however, is how to choose the system best suited for their facility among the many UV-C surface disinfection delivery systems available and how to build a case for acquisition to present to the hospital administration/C-suite. This article proposes an approach to these dilemmas based in part on the experience of 2 health care networks. Copyright © 2017 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.

Efficacy of ultraviolet light exposure against survival of Listeria monocytogenes on conveyor belts.

PubMed

Morey, Amit; McKee, Shelly R; Dickson, James S; Singh, Manpreet

2010-06-01

Listeria monocytogenes has been repeatedly isolated from foods and food-processing facilities including food contact surfaces such as conveyor belts (CB). CBs are often difficult to clean and require rigorous sanitation programs for decontamination. Ultraviolet (UV) light has exhibited microbicidal properties on food contact surfaces and this study was conducted to determine the efficacy of UV against L. monocytogenes on CB made of different materials. A four-strain cocktail of L. monocytogenes (serotypes 3A, 4A, 4B, and 4C) was made to give a suspension of approximately 10(7) CFU/mL. CBs made from four different types of materials, (1) Ropanyl DM 8/2 A2 + 04 (belt 1), (2) Volta FRMW-3.0 (belt 2), (3) Volta FRMB-3.0 (belt 3), and (4) Ropanyl DM (belt 4), were inoculated with 1 mL of the four-strain cocktail (approximately 10(7) CFU/mL) of the bacterial suspension. CBs were treated with UV light (254 nm) for 1 and 3 sec at 5.53 and 5.95 mW/cm(2). Three replications of the experiments were conducted. Two-way analysis of variance of survival populations of L. monocytogenes showed that bacterial counts were significantly reduced (p < 0.05) on all belt types irrespective of UV light intensities and times of exposure. L. monocytogenes populations were reduced (p < 0.05) to below detection limits on belts 1, 2, and 3 after exposure to 5.95 mW/cm(2) UV light intensity for 3 sec. L. monocytogenes-inoculated CBs that were exposed to 5.53 mW/cm(2) showed higher (p < 0.05) survival populations of L. monocytogenes compared with 5.95 mW/cm(2) on all the four CBs. Belt 4 showed survival populations of L. monocytogenes ranging from 1.42 to 1.73 log(10) CFU/cm(2) after UV light treatment for 1 and 3 sec. UV light can be effectively used to reduce L. monocytogenes contamination on CBs.

Review of lunar telescope studies at MSFC

NASA Astrophysics Data System (ADS)

Hilchey, John D.; Nein, Max E.

1993-09-01

In the near future astronomers can take advantage of the lunar surface as the new 'high ground' from which to study the universe. Optical telescopes placed and operated on the lunar surface would be successors to NASA's Great Observatories. Four telescopes, ranging in aperture from a 16-m, IR/Vis/UV observatory down to a 1-m, UV 'transit' instrument, have been studied by the Lunar Telescope Working Group and the LUTE (lunar telescope ultraviolet experiment) Task Team of the Marshall Space Flight Center (MSFC). This paper presents conceptual designs of the telescopes, provides descriptions of the telescope subsystem options selected for each concept, and outlines the potential evolution of their science capabilities.

Characterization and mechanism of He plasma pretreatment of nanoscale polymer masks for improved pattern transfer fidelity

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

Weilnboeck, F.; Metzler, D.; Kumar, N.

2011-12-26

Roughening of nanoscale polymer masks during plasma etching (PE) limits feature critical dimensions in current and future lithographic technologies. Roughness formation of 193 nm photoresist (PR) is mechanistically explained by plasma-induced changes in mechanical properties introduced at the PR surface ({approx}2 nm) by ions and in parallel in the material bulk ({approx}200 nm) by ultraviolet (UV) plasma radiation. Synergistic roughening of polymer masks can be prevented by pretreating PR patterns with a high dose of He plasma UV exposure to saturate bulk material modifications. During subsequent PE, PR patterns are stabilized and exhibit improved etch resistance and reduced surface/line-edge roughness.

UV/O3 treatment as a surface modification of rice husk towards preparation of novel biocomposites

PubMed Central

Rajendran Royan, Nishata Royan; Sulong, Abu Bakar; Yuhana, Nor Yuliana; Ab Ghani, Mohd Hafizuddin; Ahmad, Sahrim

2018-01-01

The use of rice husks (RH) to reinforce polymers in biocomposites are increasing tremendously. However, the incompatibility between the hydrophilic RH fibers and the hydrophobic thermoplastic matrices leads to unsatisfactory biocomposites. Surface modification of the fiber surface was carried out to improve the adhesion between fiber and matrix. In this study, the effect of surface modification of RH via alkali, acid and ultraviolet-ozonolysis (UV/O3) treatments on the properties of composites recycled high density polyethylene (rHDPE) composites was investigated. The untreated and treated RH were characterized by Fourier Transform Infrared (FTIR) and Scanning Electron Microscope (SEM). The composites containing 30 wt% of RH (treated and untreated) were then prepared via extrusion and followed by compression molding. As compared to untreated RH, all surface treated RH exhibited rougher surface and showed improved adhesion with rHDPE matrix. Tensile strength of UV/O3-treated RH composites showed an optimum result at 18.37 MPa which improved about 5% in comparison to the composites filled with untreated RH. UV/O3 treatment promotes shorter processing time and lesser raw material waste during treatment process where this is beneficial for commercialization in the future developments of wood plastic composites (WPCs). Therefore, UV/O3 treatment can be served as an alternative new method to modify RH surface in order to improve the adhesion between hydrophilic RH fibre and hydrophobic rHDPE polymer matrix. PMID:29847568

Temperature Effects of Ultraviolet Irradiation on Material Degradation

NASA Astrophysics Data System (ADS)

Mori, Kazuyuki; Ishizawa, Junichiro

Ultraviolet rays (UV) cause organic materials to deteriorate. UV irradiation ground testing is therefore important to understand the “adequate lifetime assessment” and the “end-of-life (EOL) characteristic” of materials used in space. In previous experiments, high temperatures were found to accelerate the UV degradation of cross-linked ethylene tetrafluoroethylene (X-ETFE). This causes concern of potentially similar effects in other materials. In this study, we evaluated UV degradation at high temperatures and subsequently determined materials usable in space that had shown accelerated degradation due to UV irradiation at high temperatures.

Indium gallium nitride-based ultraviolet, blue, and green light-emitting diodes functionalized with shallow periodic hole patterns

PubMed Central

Jeong, Hyun; Salas-Montiel, Rafael; Lerondel, Gilles; Jeong, Mun Seok

2017-01-01

In this study, we investigated the improvement in the light output power of indium gallium nitride (InGaN)-based ultraviolet (UV), blue, and green light-emitting diodes (LEDs) by fabricating shallow periodic hole patterns (PHPs) on the LED surface through laser interference lithography and inductively coupled plasma etching. Noticeably, different enhancements were observed in the light output powers of the UV, blue, and green LEDs with negligible changes in the electrical properties in the light output power versus current and current versus voltage curves. In addition, confocal scanning electroluminescence microscopy is employed to verify the correlation between the enhancement in the light output power of the LEDs with PHPs and carrier localization of InGaN/GaN multiple quantum wells. Light propagation through the PHPs on the UV, blue, and green LEDs is simulated using a three-dimensional finite-difference time-domain method to confirm the experimental results. Finally, we suggest optimal conditions of PHPs for improving the light output power of InGaN LEDs based on the experimental and theoretical results. PMID:28374856

Indium gallium nitride-based ultraviolet, blue, and green light-emitting diodes functionalized with shallow periodic hole patterns.

PubMed

Jeong, Hyun; Salas-Montiel, Rafael; Lerondel, Gilles; Jeong, Mun Seok

2017-04-04

In this study, we investigated the improvement in the light output power of indium gallium nitride (InGaN)-based ultraviolet (UV), blue, and green light-emitting diodes (LEDs) by fabricating shallow periodic hole patterns (PHPs) on the LED surface through laser interference lithography and inductively coupled plasma etching. Noticeably, different enhancements were observed in the light output powers of the UV, blue, and green LEDs with negligible changes in the electrical properties in the light output power versus current and current versus voltage curves. In addition, confocal scanning electroluminescence microscopy is employed to verify the correlation between the enhancement in the light output power of the LEDs with PHPs and carrier localization of InGaN/GaN multiple quantum wells. Light propagation through the PHPs on the UV, blue, and green LEDs is simulated using a three-dimensional finite-difference time-domain method to confirm the experimental results. Finally, we suggest optimal conditions of PHPs for improving the light output power of InGaN LEDs based on the experimental and theoretical results.

Fiscal Year 2011 Director’s Strategic Initiative Final Report Heterogeneous Device Architectures Incorporating Nitride Semiconductors for Enhanced Functionality of Optoelectronic Devices

DTIC Science & Technology

2014-03-01

electromagnetic radiation across the spectrum from the ultraviolet ( UV ) to terahertz, heterogeneous integration of these materials with others having different...weak absorption that limit the QE of homogenous SiC-based photodetectors in the deep UV and near UV regions, respectively. Furthermore, we have...Polarization-Enhanced III-Nitride-SiC Avalanche Photodiodes Semiconductor-based ultraviolet ( UV ) avalanche photodetectors (APDs) have significant promise

Space Weathering Effects at UV Wavelengths: Asteroids and the Moon

NASA Astrophysics Data System (ADS)

Hendrix, Amanda; Vilas, F.

2006-09-01

Space weathering, the bombardment of airless bodies by micrometeoroids and irradiation by solar wind particles, affects spectra of solar system bodies at visible/near IR (VNIR) wavelengths by darkening and reddening their surface materials, as well as degrading absorption features. We present new results detailing space weathering effects at ultraviolet wavelengths. We focus on new spectral modeling results, and also present spacecraft data of asteroids and the Moon, along with new UV measurements of asteroid families from HST, to demonstrate the effects of varying degrees of weathering and the outcome of weathering on surfaces of different compositions. Weathered surfaces are relatively bright and spectrally blue in the UV; these UV effects can be more obvious than the VNIR effects. The cause of these weathering effects is likely vapor deposition of submicroscopic iron (SMFe), through solar wind irradiation and micrometeoroid bombardment of the bodies' surfaces. In silicate minerals, the NUV region is dominated by a decrease in reflectance with wavelength - the "UV absorption edge.” In contrast to silicates, iron is opaque and relatively bright in the UV, so the addition of SMFe to a silicate grains has the effect of making the UV region brighter; this is in opposition to the situation at longer wavelengths, where the addition of SMFe decreases the albedo. Our spectral modeling results show that the addition of SMFe decreases the steepness of the UV dropoff, in effect making the UV spectrum bluer. This can explain the difference in UV spectral behavior seen between S-class asteroids and less-weathered ordinary chondrite meteorites, and between lunar rocks and more weathered lunar soils. This work is funded in part by Hubble Space Telescope Grant #10557.

The World Space Observatory Ultraviolet (WSO-UV), as a bridge to future UV astronomy

NASA Astrophysics Data System (ADS)

Shustov, B.; Gómez de Castro, A. I.; Sachkov, M.; Vallejo, J. C.; Marcos-Arenal, P.; Kanev, E.; Savanov, I.; Shugarov, A.; Sichevskii, S.

2018-04-01

Ultraviolet (UV) astronomy is a vital branch of space astronomy. Many dozens of short-term UV-experiments in space, as well as long-term observatories, have brought a very important knowledge on the physics and chemistry of the Universe during the last decades. Unfortunately, no large UV-observatories are planned to be launched by most of space agencies in the coming 10-15 years. Conversely, the large UVOIR observatories of the future will appear not earlier than in 2030s. This paper briefly describes the projects that have been proposed by various groups. We conclude that the World Space Observatory-Ultraviolet (WSO-UV) will be the only 2-m class UV telescope with capabilities similar to those of the HST for the next decade. The WSO-UV has been described in detail in previous publications, and this paper updates the main characteristics of its instruments and the current state of the whole project. It also addresses the major science topics that have been included in the core program of the WSO-UV, making this core program very relevant to the current state of the UV-astronomy. Finally, we also present here the ground segment architecture that will implement this program.

The S-layer Protein DR_2577 Binds Deinoxanthin and under Desiccation Conditions Protects against UV-Radiation in Deinococcus radiodurans

PubMed Central

Farci, Domenica; Slavov, Chavdar; Tramontano, Enzo; Piano, Dario

2016-01-01

Deinococcus radiodurans has the puzzling ability to withstand over a broad range of extreme conditions including high doses of ultraviolet radiation and deep desiccation. This bacterium is surrounded by a surface layer (S-layer) built of a regular repetition of several proteins, assembled to form a paracrystalline structure. Here we report that the deletion of a main constituent of this S-layer, the gene DR_2577, causes a decrease in the UVC resistance, especially in desiccated cells. Moreover, we show that the DR_2577 protein binds the carotenoid deinoxanthin, a strong protective antioxidant specific of this bacterium. A further spectroscopical characterization of the deinoxanthin-DR_2577 complex revealed features which could suggest a protective role of DR_2577. We propose that, especially under desiccation, the S-layer shields the bacterium from incident ultraviolet light and could behave as a first lane of defense against UV radiation. PMID:26909071

The S-layer Protein DR_2577 Binds Deinoxanthin and under Desiccation Conditions Protects against UV-Radiation in Deinococcus radiodurans.

PubMed

Farci, Domenica; Slavov, Chavdar; Tramontano, Enzo; Piano, Dario

2016-01-01

Deinococcus radiodurans has the puzzling ability to withstand over a broad range of extreme conditions including high doses of ultraviolet radiation and deep desiccation. This bacterium is surrounded by a surface layer (S-layer) built of a regular repetition of several proteins, assembled to form a paracrystalline structure. Here we report that the deletion of a main constituent of this S-layer, the gene DR_2577, causes a decrease in the UVC resistance, especially in desiccated cells. Moreover, we show that the DR_2577 protein binds the carotenoid deinoxanthin, a strong protective antioxidant specific of this bacterium. A further spectroscopical characterization of the deinoxanthin-DR_2577 complex revealed features which could suggest a protective role of DR_2577. We propose that, especially under desiccation, the S-layer shields the bacterium from incident ultraviolet light and could behave as a first lane of defense against UV radiation.

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

PubMed

Wadsworth, Jennifer; Cockell, Charles S

2017-05-01

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

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

PubMed

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.

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

PubMed

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

2014-08-15

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

Growth of delta-doped layers on silicon CCD/S for enhanced ultraviolet response

NASA Technical Reports Server (NTRS)

Hoenk, Michael E. (Inventor); Grunthaner, Paula J. (Inventor); Grunthaner, Frank J. (Inventor); Terhune, Robert W. (Inventor); Hecht, Michael H. (Inventor)

1994-01-01

The backside surface potential well of a backside-illuminated CCD is confined to within about half a nanometer of the surface by using molecular beam epitaxy (MBE) to grow a delta-doped silicon layer on the back surface. Delta-doping in an MBE process is achieved by temporarily interrupting the evaporated silicon source during MBE growth without interrupting the evaporated p+ dopant source (e.g., boron). This produces an extremely sharp dopant profile in which the dopant is confined to only a few atomic layers, creating an electric field high enough to confine the backside surface potential well to within half a nanometer of the surface. Because the probability of UV-generated electrons being trapped by such a narrow potential well is low, the internal quantum efficiency of the CCD is nearly 100% throughout the UV wavelength range. Furthermore, the quantum efficiency is quite stable.

DEMONSTRATION BULLETIN - ULTROX INTERNATIONAL, INC. ULTRAVIOLET RADIATION AND OXIDATION

EPA Science Inventory

The ultraviolet (UV) radiation/oxidation treatment technology developed by Ultrox International uses a combination of UV radiation, ozone, and hydrogen peroxide to oxidize organic compounds in water. Various operating parameters can be adjusted in the Ultrox® system to enhan...

Growth, yield and tuber quality of Solanum tuberosum L. under supplemental ultraviolet-B radiation at different NPK levels.

PubMed

Singh, S; Kumari, R; Agrawal, M; Agrawal, S B

2011-05-01

In many areas, decreases in the stratospheric ozone layer have resulted in an increase in ultraviolet-B (UV-B, 280-315 nm) radiation reaching the Earth's surface. The present study was conducted to evaluate the interactive effects of supplemental UV-B (sUV-B) and mineral nutrients on a tuber crop, potato (Solanum tuberosum L. var Kufri Badshah), under natural field conditions in a dry tropical environment. The nutrient treatments were the recommended dose of NPK (F(o)), 1.5 times the recommended dose of NPK (F(1)), 1.5 times the recommended dose of N (F(2)) and 1.5 times the recommended dose of K (F(3)). The response of potato plants to sUV-B varied with nutrient treatment and concentration. sUV-B adversely affected growth, yield and quality of tubers, causing an increase in reducing sugars in the tubers and thus reducing the economic value. Growth and fresh weight of tubers was maximal with sUV-B at 1.5 times recommended NPK, but the dry weight of tubers were highest with the recommended NPK dose. Reducing sugar content was lower in potato plants treated with sUV-B and the recommended NPK than with sUV-B and 1.5 times the recommended NPK. This study thus clearly shows that growing potato with 1.5 times the recommended NPK or 1.5 times the recommended dose of N/K does not alleviate the sUV-B induced changes in yield and quality of tubers compared to the recommended NPK dose. © 2010 German Botanical Society and The Royal Botanical Society of the Netherlands.

Ultraviolet-ozone treatment reduces levels of disease-associated prion protein and prion infectivity

USGS Publications Warehouse

Johnson, C.J.; Gilbert, P.; McKenzie, D.; Pedersen, J.A.; Aiken, Judd M.

2009-01-01

Background. Transmissible spongiform encephalopathies (TSEs) are a group of fatal neurodegenerative diseases caused by novel infectious agents referred to as prions. Prions appear to be composed primarily, if not exclusively, of a misfolded isoform of the cellular prion protein. TSE infectivity is remarkably stable and can resist many aggressive decontamination procedures, increasing human, livestock and wildlife exposure to TSEs. Findings. We tested the hypothesis that UV-ozone treatment reduces levels of the pathogenic prion protein and inactivates the infectious agent. We found that UV-ozone treatment decreased the carbon and prion protein content in infected brain homogenate to levels undetectable by dry-ashing carbon analysis or immunoblotting, respectively. After 8 weeks of ashing, UV-ozone treatment reduced the infectious titer of treated material by a factor of at least 105. A small amount of infectivity, however, persisted despite UV-ozone treatment. When bound to either montmorillonite clay or quartz surfaces, PrPTSE was still susceptible to degradation by UV-ozone. Conclusion. Our findings strongly suggest that UV-ozone treatment can degrade pathogenic prion protein and inactivate prions, even when the agent is associated with surfaces. Using larger UV-ozone doses or combining UV-ozone treatment with other decontaminant methods may allow the sterilization of TSE-contaminated materials. ?? 2009 Aiken et al; licensee BioMed Central Ltd.

Spectral dependence on the correction factor of erythemal UV for cloud, aerosol, total ozone, and surface properties: A modeling study

NASA Astrophysics Data System (ADS)

Park, Sang Seo; Jung, Yeonjin; Lee, Yun Gon

2016-07-01

Radiative transfer model simulations were used to investigate the erythemal ultraviolet (EUV) correction factors by separating the UV-A and UV-B spectral ranges. The correction factor was defined as the ratio of EUV caused by changing the amounts and characteristics of the extinction and scattering materials. The EUV correction factors (CFEUV) for UV-A [CFEUV(A)] and UV-B [CFEUV(B)] were affected by changes in the total ozone, optical depths of aerosol and cloud, and the solar zenith angle. The differences between CFEUV(A) and CFEUV(B) were also estimated as a function of solar zenith angle, the optical depths of aerosol and cloud, and total ozone. The differences between CFEUV(A) and CFEUV(B) ranged from -5.0% to 25.0% for aerosols, and from -9.5% to 2.0% for clouds in all simulations for different solar zenith angles and optical depths of aerosol and cloud. The rate of decline of CFEUV per unit optical depth between UV-A and UV-B differed by up to 20% for the same aerosol and cloud conditions. For total ozone, the variation in CFEUV(A) was negligible compared with that in CFEUV(B) because of the effective spectral range of the ozone absorption band. In addition, the sensitivity of the CFEUVs due to changes in surface conditions (i.e., surface albedo and surface altitude) was also estimated by using the model in this study. For changes in surface albedo, the sensitivity of the CFEUVs was 2.9%-4.1% per 0.1 albedo change, depending on the amount of aerosols or clouds. For changes in surface altitude, the sensitivity of CFEUV(B) was twice that of CFEUV(A), because the Rayleigh optical depth increased significantly at shorter wavelengths.

ARC-1979-AC79-7104

NASA Image and Video Library

1979-07-07

Range : 1,094,666 km (677,000 mi.) This false color picture of Callisto was taken by Voyager 2 and is centered on 11 degrees N and 171 degrees W. This rendition uses an ultraviolet image for the blue component. Because the surface displays regional contrast in UV, variations in surface materials are apparent. Notice in particular the dark blue haloes which surround bright craters in the eastern hemisphere. The surface of Callisto is the most heavily cratered of the Galilean satellites and resembles ancient heavily cratered terrains on the moon, Mercury and Mars. The bright areas are ejecta thrown out by relatively young impact craters. A large ringed structure, probably an impact basin, is shown in the upper left part of the picture. The color version of this picture was constructed by compositing black and white images taken through the ultraviolet, clear and orange filters.

The endogenous hormones in soybean seedlings under the joint actions of rare earth element La(III) and ultraviolet-B stress.

PubMed

Peng, Qi; Zhou, Qing

2009-12-01

The dynamic state of endogenous hormone content in soybean seedlings was investigated for a further demonstration of alleviating the damage of the ultraviolet ultraviolet-B (UV-B) radiation in the La(III)-treated soybean seedlings under UV-B stress. Using hydroponics culture, the effects of lanthanum(III) on the contents of endogenous hormone under elevated ultraviolet-B radiation (280–320 nm) was studied. The results showed that the content of indole-3-acetic acid (IAA) in soybean seedlings decreased initially and then increased when the seedlings underwent UV-B treatment during the stress and convalescent period; this was compared with a control; acetic acid oxidase (IAAO) activity increased at first (first to fifth day) and then decreased (sixth to 11th day). A similar change of abscisic acid content and IAAO content in soybean seedlings occurred; gibberellic acid (GA) content decreased during the experiment compared with control. The content of IAA and GA in soybean seedlings with La(III) + UV-B treatment was higher than those of UV-B treatment; IAAO activity and GA content in soybean seedlings with La (III) + UV-B treatment were lower than those of UV-B treatment. It suggested that the regulative effect of La(III) at the optimum concentration on endogenous hormone improved the ability of plant stress resistance, and its protective effect against low UV-B radiation was superior to high UV-B radiation. The defensive effect of La(III) on soybean seedlings under UV-B stress was carried out on the layer of defense system.

Evaluation of Filtration and UV Disinfection for Inactivation of ...

EPA Pesticide Factsheets

This study evaluated filtration and disinfection processes for removal and inactivation of pathogens in non-community water systems (NCWS) in two surface water supplies. Pretreatment systems included 1) pressure sand filtration, and 2) granular activated carbon adsorption, and 3) cartridge filtration. Two types of low-pressure UV systems were evaluated with and without pretreatment systems. The presentation will provide results for removal of particles and inactivation of MS2 bacteriophage (a viral surrogate) on two surface waters in northeastern Minnesota. Several studies, including a recent study conducted by Minnesota Department of Health (MDH), show that viruses occur in groundwater at a higher rate than expected. Based on preliminary results in Minnesota, virus occurrence appears to be correlated with recharge events such as heavy rainfall and snowmelt. These recharge events are predicted to become more extreme due to climate change impacts. Filtration, ultraviolet (UV) disinfection, and chlorination, can provide a multi-barrier approach for removal or inactivation of pathogens and DBP precursors in both groundwater and surface water systems.

Assessing the effects of ultraviolet radiation on the photosynthetic potential in Archean marine environments

NASA Astrophysics Data System (ADS)

Avila-Alonso, Dailé; Baetens, Jan M.; Cardenas, Rolando; de Baets, Bernard

2017-07-01

In this work, the photosynthesis model presented by Avila et al. in 2013 is extended and more scenarios inhabited by ancient cyanobacteria are investigated to quantify the effects of ultraviolet (UV) radiation on their photosynthetic potential in marine environments of the Archean eon. We consider ferrous ions as blockers of UV during the Early Archean, while the absorption spectrum of chlorophyll a is used to quantify the fraction of photosynthetically active radiation absorbed by photosynthetic organisms. UV could have induced photoinhibition at the water surface, thereby strongly affecting the species with low light use efficiency. A higher photosynthetic potential in early marine environments was shown than in the Late Archean as a consequence of the attenuation of UVC and UVB by iron ions, which probably played an important role in the protection of ancient free-floating bacteria from high-intensity UV radiation. Photosynthetic organisms in Archean coastal and ocean environments were probably abundant in the first 5 and 25 m of the water column, respectively. However, species with a relatively high efficiency in the use of light could have inhabited ocean waters up to a depth of 200 m and show a Deep Chlorophyll Maximum near 60 m depth. We show that the electromagnetic radiation from the Sun, both UV and visible light, could have determined the vertical distribution of Archean marine photosynthetic organisms.

Surface exciton emission of MgO crystals

NASA Astrophysics Data System (ADS)

Kuang, Wen-Jian; Li, Qing; Chen, Yu-Xiang; Hu, Kai; Wang, Ning-Hui; Xing, Fang-Li; Yan, Qun; Sun, Shuai-Shuai; Huang, Yan; Tao, Ye; Tolner, Harm

2013-09-01

MgO crystals have been exposed to vacuum ultraviolet (VUV) radiation from a synchrotron, with energies up to 9 eV, and the emitted light, at wavelengths above 200 nm, was observed. It is concluded that bulk excitons, play an important role in the diffusion of energy inside MgO crystals, resulting in 5.85 eV (212 nm) emission from the MgO terraces of large (0.2-2 µm) MgO : F crystals. In the case of aliovalent impurity doping, then the bulk exciton energy is also transferred to the Vk centres and 5.3 eV (235 nm) light is emitted. Both fluorine and silicon doping appear to promote UV surface emission, acting similarly to an ns2 ion inside MgO, while strong scandium doping is killing the surface emission completely. The 212 nm surface UV emission and the 235 nm bulk UV emission can be excited only at the bandgap edge. Broadband visible light, centred around 400 nm, is also emitted. Contrary to the UV emission, this is not generated when excited at the bandgap edge; instead, we find that it is only excited at sub-bandgap energies, with a maximum at the 5C surface excitation energy of 5.71 eV (217 nm) for the MgO terraces.

Simulation of photons from plasmas for the applications to display devices

NASA Astrophysics Data System (ADS)

Lee, Hae June; Yoon, Hyun Jin; Lee, Jae Koo

2007-07-01

Numerical modeling of the photon transport of the ultraviolet (UV) and the visible lights are presented for plasma based display devices. The transport of UV lights which undergo resonance trapping by ground state atoms is solved by using the Holstein equation. After the UV lights are transformed to visible lights at the phosphor surfaces, the visible lights experience complicated traces inside the cell and finally are emitted toward the viewing window after having some power loss within the cell. A three-dimensional ray trace of the visible lights is calculated with a radiosity model. These simulations for the photons strengthen plasma discharge modeling for the application to display devices.

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

PubMed

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.

Novel antioxidant capability of titanium induced by UV light treatment.

PubMed

Ueno, Takeshi; Ikeda, Takayuki; Tsukimura, Naoki; Ishijima, Manabu; Minamikawa, Hajime; Sugita, Yoshihiko; Yamada, Masahiro; Wakabayashi, Noriyuki; Ogawa, Takahiro

2016-11-01

The intracellular production of reactive oxygen species (ROS) is a representative form of cellular oxidative stress and plays an important role in triggering adverse cellular events, such as the inflammatory reaction and delayed or compromised differentiation. Osteoblastic reaction to titanium with particular focus on ROS production remains unknown. Ultraviolet (UV) light treatment improves the physicochemical properties of titanium, specifically the induction of super hydrophilicity and removal of hydrocarbon, and eventually enhances its osteoconductivity. We hypothesized that there is a favorable regulatory change of ROS production within osteoblasts in contact with UV-treated titanium. Osteoblasts were cultured on titanium disks with or without UV-pretreatment. The intracellular production of ROS was higher on acid-etch-created rough titanium surfaces than on machine-prepared smooth ones. The ROS production was reduced by 40-50% by UV pretreatment of titanium regardless of the surface roughness. Oxidative DNA damage, as detected by 8-OHdG expression, was alleviated by 50% on UV-treated titanium surfaces. The expression of inflammatory cytokines was consistently lower in osteoblasts cultured on UV-treated titanium. ROS scavenger, glutathione, remained more without being depleted in osteoblasts on UV-treated titanium. Bio-burden test further showed that culturing osteoblasts on UV-treated titanium can significantly reduce the ROS production even with the presence of hydrogen peroxide, an oxidative stress inducer. These data suggest that the intracellular production of ROS and relevant inflammatory reaction, which unavoidably occurs in osteoblasts in contact with titanium, can be significantly reduced by UV pretreatment of titanium, implying a novel antioxidant capability of the particular titanium. Copyright © 2016 Elsevier Ltd. All rights reserved.

CHALLENGES OF COMBINED SEWER OVERFLOW DISINFECTION BY ULTRAVIOLET LIGHT IRRADIATION

EPA Science Inventory

This article examines the performance and effectiveness of ultraviolet (UV) light irradiation for disinfection of combined sewer overflow (CSO). Due to the negative impact of conventional water disinfectants on aquatic life, new agents (e.g., UV light) are being investigated for ...

ULTRAVIOLET RADIATION AND ARSENIC INTERACTIONS: EFFECTS ON CLADOCERANS

EPA Science Inventory

The effects of arsenic and ultraviolet radiation (UV) on cladocerans have been examined separately, however the interaction of these two stresses has not been explored. Potential synergism between these two stresses is possible as arsenic is known to inhibit repair of UV induced ...

Bias Selectable Dual Band AlGaN Ultra-violet Detectors

NASA Technical Reports Server (NTRS)

Yan, Feng; Miko, Laddawan; Franz, David; Guan, Bing; Stahle, Carl M.

2007-01-01

Bias selectable dual band AlGaN ultra-violet (UV) detectors, which can separate UV-A and UV-B using one detector in the same pixel by bias switching, have been designed, fabricated and characterized. A two-terminal n-p-n photo-transistor-like structure was used. When a forward bias is applied between the top electrode and the bottom electrode, the detectors can successfully detect W-A and reject UV-B. Under reverse bias, they can detect UV-B and reject UV-A. The proof of concept design shows that it is feasible to fabricate high performance dual-band UV detectors based on the current AlGaN material growth and fabrication technologies.

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

NASA Technical Reports Server (NTRS)

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.

Super-hydrophobic surfaces of SiO₂-coated SiC nanowires: fabrication, mechanism and ultraviolet-durable super-hydrophobicity.

PubMed

Zhao, Jian; Li, Zhenjiang; Zhang, Meng; Meng, Alan

2015-04-15

The interest in highly water-repellent surfaces of SiO2-coated SiC nanowires has grown in recent years due to the desire for self-cleaning and anticorrosive surfaces. It is imperative that a simple chemical treatment with fluoroalkylsilane (FAS, CF3(CF2)7CH2CH2Si(OC2H5)3) in ethanol solution at room temperature resulted in super-hydrophobic surfaces of SiO2-coated SiC nanowires. The static water contact angle of SiO2-coated SiC nanowires surfaces was changed from 0° to 153° and the morphology, microstructure and crystal phase of the products were almost no transformation before and after super-hydrophobic treatment. Moreover, a mechanism was expounded reasonably, which could elucidate the reasons for their super-hydrophobic behavior. It is important that the super-hydrophobic surfaces of SiO2-coated SiC nanowires possessed ultraviolet-durable (UV-durable) super-hydrophobicity. Copyright © 2014 Elsevier Inc. All rights reserved.

Lunar UV-visible-IR mapping interferometric spectrometer

NASA Technical Reports Server (NTRS)

Smith, W. Hayden; Haskin, L.; Korotev, R.; Arvidson, R.; Mckinnon, W.; Hapke, B.; Larson, S.; Lucey, P.

1992-01-01

Ultraviolet-visible-infrared mapping digital array scanned interferometers for lunar compositional surveys was developed. The research has defined a no-moving-parts, low-weight and low-power, high-throughput, and electronically adaptable digital array scanned interferometer that achieves measurement objectives encompassing and improving upon all the requirements defined by the LEXSWIG for lunar mineralogical investigation. In addition, LUMIS provides a new, important, ultraviolet spectral mapping, high-spatial-resolution line scan camera, and multispectral camera capabilities. An instrument configuration optimized for spectral mapping and imaging of the lunar surface and provide spectral results in support of the instrument design are described.

Response of Two Legumes to Two Ultraviolet-B Radiation Regimes

NASA Technical Reports Server (NTRS)

Levy, Daniel L.; Skiles, J. W.

2000-01-01

Depletion of the stratospheric ozone layer has been directly linked to increased levels of UV radiation at the earth's surface. The purpose of this study was to evaluate the responses of soybean (Glycine max) and alfalfa (Medicago sativa) to increased UV-B radiation (280-320 nm). Soybean and alfalfa were grown successively in a growth chamber that provided UV-B intensities 45% above nominal summer field levels. Mylar-D (UVB opaque) and mono-acetate (UV-B transparent) films were used to establish the two UV-B treatments. Soybean grown under increased UV showed 21% smaller internodal lengths and higher concentrations of UV-B absorbing pigments (i.e. flavonoids) compared to plants grown under no UV. Significant results for alfalfa included 22% greater leaf flavonoid concentration under increased UV, 14% greater leaf chlorophyll concentration under no UV, and 32% greater above-ground biomass with no UV. These leguminous species possess mechanisms that protect against UV-B damage as indicated by increases in foliar concentrations of UV-B absorbing compounds. Alfalfa appears to be more sensitive to UV-B damage than soybean. Remote sensing of chlorophyll fluorescence may offer a means of monitoring UV-induced plant stress and damage.

Analysis of ultraviolet exposure effects on the surface properties of epoxy/graphene nanocomposite films on Mylar substrate

NASA Astrophysics Data System (ADS)

Clausi, Marialaura; Santonicola, M. Gabriella; Schirone, Luigi; Laurenzi, Susanna

2017-05-01

In this paper, we present a study of the effects generated by exposure to UV-C radiation on nanocomposite films made of graphene nanoplatelets dispersed in an epoxy matrix. The nanocomposite films, at different nanoparticle size and concentration, were fabricated on Mylar substrate using the spin coating process. The effects of UV-C irradiation on the surface hydrophobicity and on the electrical properties of the epoxy/graphene films were investigated using contact angle measurements and electrical impedance spectroscopy, respectively. According to our results, the UV-C irradiation selectively degrades the polymer matrix of the nanocomposite films, giving rise to more conductive and hydrophobic layers due to exposure of the graphene component of the composite material. The results presented here have important implications in the design of spacecraft components and structures destined for long-term space missions.

UV-blocking spectacle lens protects against UV-induced decline of visual performance.

PubMed

Liou, Jyh-Cheng; Teng, Mei-Ching; Tsai, Yun-Shan; Lin, En-Chieh; Chen, Bo-Yie

2015-01-01

Excessive exposure to sunlight may be a risk factor for ocular diseases and reduced visual performance. This study was designed to examine the ability of an ultraviolet (UV)-blocking spectacle lens to prevent visual acuity decline and ocular surface disorders in a mouse model of UVB-induced photokeratitis. Mice were divided into 4 groups (10 mice per group): (1) a blank control group (no exposure to UV radiation), (2) a UVB/no lens group (mice exposed to UVB rays, but without lens protection), (3) a UVB/UV400 group (mice exposed to UVB rays and protected using the CR-39™ spectacle lens [UV400 coating]), and (4) a UVB/photochromic group (mice exposed to UVB rays and protected using the CR-39™ spectacle lens [photochromic coating]). We investigated UVB-induced changes in visual acuity and in corneal smoothness, opacity, and lissamine green staining. We also evaluated the correlation between visual acuity decline and changes to the corneal surface parameters. Tissue sections were prepared and stained immunohistochemically to evaluate the structural integrity of the cornea and conjunctiva. In blank controls, the cornea remained undamaged, whereas in UVB-exposed mice, the corneal surface was disrupted; this disruption significantly correlated with a concomitant decline in visual acuity. Both the UVB/UV400 and UVB/photochromic groups had sharper visual acuity and a healthier corneal surface than the UVB/no lens group. Eyes in both protected groups also showed better corneal and conjunctival structural integrity than unprotected eyes. Furthermore, there were fewer apoptotic cells and less polymorphonuclear leukocyte infiltration in corneas protected by the spectacle lenses. The model established herein reliably determines the protective effect of UV-blocking ophthalmic biomaterials, because the in vivo protection against UV-induced ocular damage and visual acuity decline was easily defined.

ADVANCED OXIDATION PROCESSES (AOPS) FOR DESTRUCTION OF METHYL TERTIARY BUTYL ETHER (MTBE -AN UNREGULATED CONTAMINANT) IN DRINKING WATER

EPA Science Inventory

Advanced oxidation processes (AOPs) provide a promising treatment option for the destruction of MTBE directly in surface and ground waters. An ongoing study is evaluating the ability of three AOPs; hydrogen peroxide/ozone (H2O2/ O3), ultraviolet irradiation/ozone (UV/O3) and ultr...

Experimental determination of photostability and fluorescence-based detection of PAHs on the Martian surface

NASA Astrophysics Data System (ADS)

Dartnell, Lewis R.; Patel, Manish R.; Storrie-Lombardi, Michael C.; Ward, John M.; Muller, Jan-Peter

2012-05-01

Even in the absence of any biosphere on Mars, organic molecules, including polycyclic aromatic hydrocarbons (PAHs), are expected on its surface due to delivery by comets and meteorites of extraterrestrial organics synthesized by astrochemistry, or perhaps in situ synthesis in ancient prebiotic chemistry. Any organic compounds exposed to the unfiltered solar ultraviolet spectrum or oxidizing surface conditions would have been readily destroyed, but discoverable caches of Martian organics may remain shielded in the subsurface or within surface rocks. We have studied the stability of three representative polycyclic aromatic hydrocarbons (PAHs) in a Mars chamber, emulating the ultraviolet spectrum of unfiltered sunlight under temperature and pressure conditions of the Martian surface. Fluorescence spectroscopy is used as a sensitive indicator of remaining PAH concentration for laboratory quantification of molecular degradation rates once exposed on the Martian surface. Fluorescence-based instrumentation has also been proposed as an effective surveying method for prebiotic organics on the Martian surface. We find the representative PAHs, anthracene, pyrene, and perylene, to have persistence half-lives once exposed on the Martian surface of between 25 and 60 h of noontime summer UV irradiation, as measured by fluorescence at their peak excitation wavelength. This equates to between 4 and 9.6 sols when the diurnal cycle of UV light intensity on the Martian surface is taken into account, giving a substantial window of opportunity for detection of organic fluorescence before photodegradation. This study thus supports the use of fluorescence-based instrumentation for surveying recently exposed material (such as from cores or drill tailings) for native Martian organic molecules in rover missions.

ULTRAVIOLET HALOS AROUND SPIRAL GALAXIES. I. MORPHOLOGY

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

Hodges-Kluck, Edmund; Cafmeyer, Julian; Bregman, Joel N., E-mail: hodgeskl@umich.edu

2016-12-10

We examine ultraviolet halos around a sample of highly inclined galaxies within 25 Mpc to measure their morphology and luminosity. Despite contamination from galactic light scattered into the wings of the point-spread function, we find that ultraviolet (UV) halos occur around each galaxy in our sample. Around most galaxies the halos form a thick, diffuse disk-like structure, but starburst galaxies with galactic superwinds have qualitatively different halos that are more extensive and have filamentary structure. The spatial coincidence of the UV halos above star-forming regions, the lack of consistent association with outflows or extraplanar ionized gas, and the strong correlationmore » between the halo and galaxy UV luminosity suggest that the UV light is an extragalactic reflection nebula. UV halos may thus represent 10{sup 6}–10{sup 7} M {sub ⊙} of dust within 2–10 kpc of the disk, whose properties may change with height in starburst galaxies.« less

Photoenhanced toxicity of a carbamate insecticide to early life stage anuran amphibians

USGS Publications Warehouse

Zaga, A.; Little, E.E.; Rabeni, C.F.; Ellersieck, Mark R.

1998-01-01

Aican clawed frog (Xenopus laevis) and gray tree frog (Hyla versicolor) embryos and tadpoles were exposed to sublethal levels of carbaryl, a broad-spectrum insecticide, and ultraviolet radiation to determine interactive and sublethal effects. Ultraviolet intensity (UV-B [285–320 nm] plus UV-A [321–400 nm]) was controlled with various types of plastic filters and quantified with a scanning spectroradiometer. Significant differences in swimming activity and mortality of both species were evident during the 96-h experiments. Ultraviolet-B radiation alone and carbaryl in the presence of UV-B significantly decreased swimming activity of both species. As little as 1.5% intensity of ambient solar UV-B radiation photoactivated carbaryl. Toxicity of 7.5 mg/L carbaryl increased by 10-fold in the presence of UV-B in all species and life stages tested. Our results indicate that photoenhancement by solar UV-B radiation should be considered when evaluating the toxicity of contaminants to amphibians and other organisms.

Next step in Studying the Ultraviolet Universe: WSO-UV

NASA Astrophysics Data System (ADS)

Shustov, Boris M.; Sachkov, Mikhail; Gomez De Castro, Ana

The World Space Observatory-Ultraviolet (WSO-UV) is an international space mission born as a response to the growing up demand for UV facilities by the astronomical community. In the horizon of the next 10 years, the WSO-UV will be the only 2-meters class mission in the after-HST epoch that will guarantee access to UV wavelength domain. The project is managed by an international consortium led by the Federal Space Agency (ROSCOSMOS, Russia). Here we describe the WSO-UV project with its general objectives and main features, the details and status of instrumentation that includes WUVS (spectrographs) and the ISSIS instrument (Field Camera Unit), WSO-UV ground segment, science management plan, the WSO-UV key science issues and prospects of high resolution spectroscopic studies with WSO-UV.

TOPICAL REVIEW: Climate change, ozone depletion and the impact on ultraviolet exposure of human skin

NASA Astrophysics Data System (ADS)

Diffey, Brian

2004-01-01

For 30 years there has been concern that anthropogenic damage to the Earth's stratospheric ozone layer will lead to an increase of solar ultraviolet (UV) radiation reaching the Earth's surface, with a consequent adverse impact on human health, especially to the skin. More recently, there has been an increased awareness of the interactions between ozone depletion and climate change (global warming), which could also impact on human exposure to terrestrial UV. The most serious effect of changing UV exposure of human skin is the potential rise in incidence of skin cancers. Risk estimates of this disease associated with ozone depletion suggest that an additional peak incidence of 5000 cases of skin cancer per year in the UK would occur around the mid-part of this century. Climate change, which is predicted to lead to an increased frequency of extreme temperature events and high summer temperatures, will become more frequent in the UK. This could impact on human UV exposure by encouraging people to spend more time in the sun. Whilst future social trends remain uncertain, it is likely that over this century behaviour associated with climate change, rather than ozone depletion, will be the largest determinant of sun exposure, and consequent impact on skin cancer, of the UK population.

Enhancement of the Ultraviolet Photoresponsivity of Al-doped ZnO Thin Films Prepared by using the Sol-gel Spin-coating Method

NASA Astrophysics Data System (ADS)

Lee, Wookbin; Leem, Jae-Young

2018-03-01

We report the structural, morphological, optical, and ultraviolet (UV) photoresponse properties of Al-doped ZnO (AZO) thin films prepared on silicon substrates with different Al doping concentrations by using the sol-gel spin-coating method. An analysis of the X-ray diffraction patterns of the AZO thin films revealed that the average grain size decreased and the c-axis lattice constant increased with Al content. The field-emission scanning electron microscopy images showed that with Al doping, the grain size decreased, but the film density increased with increasing Al doping concentration from 0% to 3%. These results indicate that the surface area of the film increased with increasing Al doping. The absorbance spectra revealed that the UV absorbance of the AZO thin films increased with increasing Al doping concentration and that the absorption onset shifted towards lower energies. The photoluminescence spectra revealed that with increasing Al doping, the intensity of the visible emission greatly decreased and the visible emission peak shifted forward lower energy (a red shift). The UV sensor based on the AZO thin films exhibited a higher responsivity than that based on the undoped ZnO thin film. Therefore, this study provides a facile method for improving the photoresponsivity of UV sensors.

Enhancement of pectinase production by ultraviolet irradiation and diethyl sulfate mutagenesis of a Fusarium oxysporum isolate.

PubMed

Yin, L B; Zhang, C F; Xia, Q L; Yang, Y; Xiao, K; Zhao, L Z

2016-09-23

Fusarium oxysporum strain BM-201 was treated with ultraviolet (UV) radiation to obtain a high pectinase-producing strain. Mutant UV-10-41 was obtained and then treated by diethyl sulfate. Next, the mutant UV-diethyl sulfate-43 derived from UV-10-41 was selected as high pectinase-producing strain. Mutant UV-diethyl sulfate-43 was incubated on slant for 10 generations, demonstrating that the pectinase-producing genes were stable. Pectinase activity reached 391.2 U/mL, which is 73.6% higher than that of the original strain.

Complete fluorescent fingerprints of extremophilic and photosynthetic microbes

NASA Astrophysics Data System (ADS)

Dartnell, Lewis R.; Storrie-Lombardi, Michael C.; Ward, John M.

2010-10-01

The work reported here represents a study into the total fluorescence exhibited by a broad selection of model, extremophilic and photosynthetic bacterial strains, over a great range of excitation and emission wavelengths from ultraviolet (UV) through visible to near infrared. The aim is to identify distinctive fluorescent features that may serve as detectable biosignatures of remnant microbial life on the Martian surface. A lab-bench fluorescence spectrometer was used to generate an excitation-emission matrix (EEM) for the unpigmented Escherichia coli, radiation-resistant Deinococcus radiodurans, Antarctic Dry Valley isolates Brevundimonas sp. MV.7 and Rhodococcus sp. MV.10, and the cyanobacterium Synechocystis sp. PCC 6803. Detailed EEMs, representing the fluorescence signature of each organism, are presented, and the most significant features suitable for biosignature surveys are identified, including small-molecule cellular metabolites, light-harvesting photosynthetic pigments and extracellular UV-screening compounds. E. coli exhibits the most intense emission from tryptophan, presumably due to the absence of UV-screening pigments that would shield the organism from short-wavelength light-exciting intracellular fluorescence. The efficacy of commonly available laser diodes for exciting cellular fluorescence is treated, along with the most appropriate filter wavelengths for imaging systems. The best combination of available laser diodes and PanCam filters aboard the ExoMars probe is proposed. The possibility of detecting fluorescence excited by solar UV radiation in freshly exposed surface samples by imaging when both sunlit and shadowed, perhaps by the body of the rover itself, is discussed. We also study how these biological fluorophore molecules may be degraded, and thus the potential biosignatures erased, by the high flux of far-ultraviolet light on Mars.

Inactivation of Uropathogenic Escherichia coli in Ground Chicken Meat Using High Pressure Processing and Gamma Radiation, and in Purge and Chicken Meat Surfaces by Ultraviolet Light

PubMed Central

Sommers, Christopher H.; Scullen, O. J.; Sheen, Shiowshuh

2016-01-01

Extraintestinal pathogenic Escherichia coli, including uropathogenic E. coli (UPEC), are common contaminants in poultry meat and may cause urinary tract infections after colonization of the gastrointestinal tract and transfer of contaminated feces to the urethra. Three non-thermal processing technologies used to improve the safety and shelf-life of both human and pet foods include high pressure processing (HPP), ionizing (gamma) radiation (GR), and ultraviolet light (UV-C). Multi-isolate cocktails of UPEC were inoculated into ground chicken which was then treated with HPP (4°C, 0–25 min) at 300, 400, or 500 MPa. HPP D10, the processing conditions needed to inactivate 1 log of UPEC, was 30.6, 8.37, and 4.43 min at 300, 400, and 500 MPa, respectively. When the UPEC was inoculated into ground chicken and gamma irradiated (4 and -20°C) the GR D10 were 0.28 and 0.36 kGy, respectively. The UV-C D10 of UPEC in chicken suspended in exudate and placed on stainless steel and plastic food contact surfaces ranged from 11.4 to 12.9 mJ/cm2. UV-C inactivated ca. 0.6 log of UPEC on chicken breast meat. These results indicate that existing non-thermal processing technologies such as HPP, GR, and UV-C can significantly reduce UPEC levels in poultry meat or exudate and provide safer poultry products for at-risk consumers. PMID:27148167

Ultraviolet Satellite Measurements of Volcanic Ash. Chapter 12

NASA Technical Reports Server (NTRS)

Carn, S. A.; Krotkov, N. A.

2016-01-01

Ultraviolet (UV) remote sensing of volcanic ash and other absorbing aerosols from space began with the launch of the first Total Ozone Mapping Spectrometer (TOMS) instrument in 1978. Subsequent UV satellite missions (TOMS, GOME, SCIAMACHY, OMI, GOME-2, OMPS) have extended UV ash measurements to the present, generating a unique multidecadal record. A UV Aerosol Index (UVAI) based on two near-UV wavelengths, equally applicable to multispectral (TOMS, DSCOVR) or hyperspectral (GOME, SCIAMACHY, OMI, GOME-2, OMPS) instruments, has been used to derive a unique absorbing aerosol climatology across multiple UV satellite missions. Advantages of UV ash measurements relative to infrared (IR) techniques include the ability to detect ash at any altitude (assuming no clouds), above clouds, and over bright surfaces, where visible and IR techniques may fail. Disadvantages include the daytime-only restriction and nonspecificity to silicate ash, since UV measurements are sensitive to any UV-absorbing aerosol, including smoke, desert dust, and pollution. However, simultaneous retrieval of sulfur dioxide (SO2) abundance and UVAI provides robust discrimination of volcanic clouds. Although the UVAI is only semiquantitative, it has proved successful at detecting and tracking volcanic ash clouds from many volcanic eruptions since 1978. NASA A-Train measurements since 2006 (eg, CALIOP) have provided much improved constraints on volcanic ash altitude, and also permit identification of aerosol type through sensor synergy. Quantitative UV retrievals of ash optical depth, effective particle size, and ash column mass are possible and require assumptions of ash refractive index, particle size distribution, and ash layer altitude. The lack of extensive ash refractive index data in the UV-visible and the effects of ash particle shape on retrievals introduce significant uncertainty in the retrieved parameters, although limited validation against IR ash retrievals has been successful. In this contribution, we review UV ash detection and retrieval techniques and provide examples of volcanic eruptions detected in the approx. 37 year data record.

ULTRAVIOLET LIGHT DISINFECTION OF COMBINED SEWER OVERFLOW (NEW ORLEANS)

EPA Science Inventory

The objective of this state-of-the-art review is to examine the performance and effectiveness of ultraviolet (UV) light disinfection for combined sewer overflow (CSO) applications. Topics presented include the use of UV light as a disinfecting agent, its practical applications, d...

LOW PRESSURE ULTRAVIOLET STUDIES FOR INACTIVATION OF GIARDIA MURIS CYSTS

EPA Science Inventory

This research was initiated to confirm and expand the current database for the inactivation of Giardia spp. using ultraviolet (UV) radiation. Initially, previous research that used in vitro excystation as the indicator for UV effectiveness was confirmed. Later, the in vitro excys...

Integrated oxide graphene based device for laser inactivation of pathogenic microorganisms

NASA Astrophysics Data System (ADS)

Grishkanich, Alexsandr; Ruzankina, Julia; Afanasyev, Mikhail; Paklinov, Nikita; Hafizov, Nail

2018-02-01

We develop device for virus disinfection of pathogenic microorganisms. Viral decontamination can be carried out due to hard ultraviolet irradiation and singlet oxygen destroying the genetic material of a virus capsid. UV rays can destroy DNA, leading to the formation of dimers of nucleic acids. This practically does not occur in tissues, tk. UV rays penetrate badly through them, however, the viral particles are small and UV can destroy their genetic material, RNA / DNA and the virus can not replicate. It is with the construction of the ultraviolet laser water disinfection system (UFLOV) based on the continuous and periodic pulsed ultraviolet laser sources (pump) binds to solve sterility and depyrogenation of water. It has been established that small doses of UV irradiation stimulate reproduction, and large doses cause the death of pathogenic microorganisms. The effect of a dose of ultraviolet is the result of photochemical action on the substance of a living bacterial cell or virion. Also complex photodynamic laser inactivation on graphene oxide is realized.

Single Photon Counting UV Solar-Blind Detectors Using Silicon and III-Nitride Materials

PubMed Central

Nikzad, Shouleh; Hoenk, Michael; Jewell, April D.; Hennessy, John J.; Carver, Alexander G.; Jones, Todd J.; Goodsall, Timothy M.; Hamden, Erika T.; Suvarna, Puneet; Bulmer, J.; Shahedipour-Sandvik, F.; Charbon, Edoardo; Padmanabhan, Preethi; Hancock, Bruce; Bell, L. Douglas

2016-01-01

Ultraviolet (UV) studies in astronomy, cosmology, planetary studies, biological and medical applications often require precision detection of faint objects and in many cases require photon-counting detection. We present an overview of two approaches for achieving photon counting in the UV. The first approach involves UV enhancement of photon-counting silicon detectors, including electron multiplying charge-coupled devices and avalanche photodiodes. The approach used here employs molecular beam epitaxy for delta doping and superlattice doping for surface passivation and high UV quantum efficiency. Additional UV enhancements include antireflection (AR) and solar-blind UV bandpass coatings prepared by atomic layer deposition. Quantum efficiency (QE) measurements show QE > 50% in the 100–300 nm range for detectors with simple AR coatings, and QE ≅ 80% at ~206 nm has been shown when more complex AR coatings are used. The second approach is based on avalanche photodiodes in III-nitride materials with high QE and intrinsic solar blindness. PMID:27338399

Single Photon Counting UV Solar-Blind Detectors Using Silicon and III-Nitride Materials.

PubMed

Nikzad, Shouleh; Hoenk, Michael; Jewell, April D; Hennessy, John J; Carver, Alexander G; Jones, Todd J; Goodsall, Timothy M; Hamden, Erika T; Suvarna, Puneet; Bulmer, J; Shahedipour-Sandvik, F; Charbon, Edoardo; Padmanabhan, Preethi; Hancock, Bruce; Bell, L Douglas

2016-06-21

Ultraviolet (UV) studies in astronomy, cosmology, planetary studies, biological and medical applications often require precision detection of faint objects and in many cases require photon-counting detection. We present an overview of two approaches for achieving photon counting in the UV. The first approach involves UV enhancement of photon-counting silicon detectors, including electron multiplying charge-coupled devices and avalanche photodiodes. The approach used here employs molecular beam epitaxy for delta doping and superlattice doping for surface passivation and high UV quantum efficiency. Additional UV enhancements include antireflection (AR) and solar-blind UV bandpass coatings prepared by atomic layer deposition. Quantum efficiency (QE) measurements show QE > 50% in the 100-300 nm range for detectors with simple AR coatings, and QE ≅ 80% at ~206 nm has been shown when more complex AR coatings are used. The second approach is based on avalanche photodiodes in III-nitride materials with high QE and intrinsic solar blindness.

Detection of UV Pulse from Insulators and Application in Estimating the Conditions of Insulators

NASA Astrophysics Data System (ADS)

Wang, Jingang; Chong, Junlong; Yang, Jie

2014-10-01

Solar radiation in the band of 240-280 nm is absorbed by the ozone layer in the atmosphere, and corona discharges from high-voltage apparatus emit in air mainly in the 230-405 nm range of ultraviolet (UV), so the band of 240-280 nm is called UV Solar Blind Band. When the insulators in a string deteriorate or are contaminated, the voltage distribution along the string will change, which causes the electric fields in the vicinity of insulators change and corona discharge intensifies. An UV pulse detection method to check the conditions of insulators is presented based on detecting the UV pulse among the corona discharge, then it can be confirmed that whether there exist faulty insulators and whether the surface contamination of insulators is severe for the safe operation of power systems. An UV-I Insulator Detector has been developed, and both laboratory tests and field tests have been carried out which demonstrates the practical viability of UV-I Insulator Detector for online monitoring.

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

PubMed

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.

Fungal Gene Mutation Analysis Elucidating Photoselective Enhancement of UV-C Disinfection Efficiency Toward Spoilage Agents on Fruit Surface.

PubMed

Zhu, Pinkuan; Li, Qianwen; Azad, Sepideh M; Qi, Yu; Wang, Yiwen; Jiang, Yina; Xu, Ling

2018-01-01

Short-wave ultraviolet (UV-C) treatment represents a potent, clean and safe substitute to chemical sanitizers for fresh fruit preservation. However, the dosage requirement for microbial disinfection may have negative effects on fruit quality. In this study, UV-C was found to be more efficient in killing spores of Botrytis cinerea in dark and red light conditions when compared to white and blue light. Loss of the blue light receptor gene Bcwcl1 , a homolog of wc-1 in Neurospora crassa , led to hypersensitivity to UV-C in all light conditions tested. The expression of Bcuve1 and Bcphr1 , which encode UV-damage endonuclease and photolyase, respectively, were strongly induced by white and blue light in a Bcwcl1 -dependent manner. Gene mutation analyses of Bcuve1 and Bcphr1 indicated that they synergistically contribute to survival after UV-C treatment. In vivo assays showed that UV-C (1.0 kJ/m 2 ) abolished decay in drop-inoculated fruit only if the UV-C treatment was followed by a dark period or red light, while in contrast, typical decay appeared on UV-C irradiated fruits exposed to white or blue light. In summary, blue light enhances UV-C resistance in B. cinerea by inducing expression of the UV damage repair-related enzymes, while the efficiency of UV-C application for fruit surface disinfection can be enhanced in dark or red light conditions; these principles seem to be well conserved among postharvest fungal pathogens.

Preparation and characterization of functional poly(vinylidene fluoride) (PVDF) membranes with ultraviolet-absorbing property

NASA Astrophysics Data System (ADS)

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

2018-06-01

We first reported a strategy to prepare functional poly(vinylidene fluoride) (PVDF) membranes with excellent ultraviolet-absorbing property through chemically induced grafting. Herein, the polymerizable ultraviolet (UV) absorber 2-hydroxy-4-(3-methacryloxy-2-hydroxylpropoxy) benzophenone (BPMA) made by ourselves was grafted onto the PVDF chains that have been pretreated with tetraethylammonium hydroxide (TEAH) alkaline solution. Moreover, the effect of experiment conditions such as the alkali and monomer concentrations, alkali treatment time on the UV-absorbing property of the obtained PVDF-g-PBPMA membranes were studied in detail. The chemical structure of the modified membranes was confirmed by 1H NMR, FT-IR and XPS measurements. Meanwhile, the thermal and UV-absorbing properties were characterized by TGA, DSC and UV-Vis spectrophotometer, respectively. The results indicated that BPMA side chains were successfully introduced onto PVDF backbones. Most importantly, the obtained PVDF-g-PBPMA membranes exhibited excellent UV-absorbing property. The transmittance of UV light at 300 nm decreased to as low as 0.02% and the UV light below 388 nm could be completely absorbed by the PVDF-g-PBPMA membrane made under optimal condition.

Photocatalytic antibacterial effects on TiO2-anatase upon UV-A and UV-A/VIS threshold irradiation.

PubMed

Wu, Yanyun; Geis-Gerstorfer, Jürgen; Scheideler, Lutz; Rupp, Frank

2016-01-01

Photocatalysis mediated by the anatase modification of titanium dioxide (TiO2) has shown antibacterial effects in medical applications. The aim of this study was to investigate the possibility of expanding the excitation wavelengths for photocatalytic antibacterial effects from ultraviolet (UV) into the visible light range. After deposition of salivary pellicle and adhesion of Streptococcus gordonii on anatase, different irradiation protocols were applied to induce photocatalysis: ultraviolet A (UV-A) > 320 nm; ultraviolet/visible (UV-A/VIS) light > 380 nm and > 390 nm; and VIS light 400-410 nm. A quartz crystal microbalance with dissipation (QCM-D) tests and microscopic examination were used to observe the photoinduced antibacterial effects. Salivary pellicle could be photocatalytically decomposed under all irradiation protocols. In contrast, effective photocatalytic attack of bacteria could be observed by UV-A as well as by UV-A/VIS at 380 nm < λ < 390 nm only. Wavelengths above 380 nm show promise for in situ therapeutic antifouling applications.

Two ultraviolet radiation datasets that cover China

NASA Astrophysics Data System (ADS)

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

2017-07-01

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

Problems in Assessment of the UV Penetration into Natural Waters from Space-based Measurements

NASA Technical Reports Server (NTRS)

Vasilkov, Alexander P.; Herman, Jay; Krotkov, Nickolay A.; Kahru, Mati; Mitchell, B. Greg; Hsu, Christina; Bhartia, P. K. (Technical Monitor)

2002-01-01

Satellite instruments currently provide global maps of surface UV (ultraviolet) irradiance by combining backscattered radiance data with radiative transfer models. The models are often limited by uncertainties in physical input parameters of the atmosphere and surface. Global mapping of the underwater UV irradiance creates further challenges for the models. The uncertainties in physical input parameters become more serious because of the presence of absorbing and scattering quantities caused by biological processes within the oceans. In this paper we summarize the problems encountered in the assessment of the underwater UV irradiance from space-based measurements, and propose approaches to resolve the problems. We have developed a radiative transfer scheme for computation of the UV irradiance in the atmosphere-ocean system. The scheme makes use of input parameters derived from satellite instruments such as TOMS (Total Ozone Mapping Spectrometer) and SeaWiFS (Sea-viewing Wide Field-of-view Sensor). The major problem in assessment of the surface UV irradiance is to accurately quantify the effects of clouds. Unlike the standard TOMS UV algorithm, we use the cloud fraction products available from SeaWiFS and MODIS (Moderate Resolution Imaging Spectrometer) to calculate instantaneous surface flux at the ocean surface. Daily UV doses can be calculated by assuming a model of constant cloudiness throughout the day. Both SeaWiFS and MODIS provide some estimates of seawater optical properties in the visible. To calculate the underwater UV flux the seawater optical properties must be extrapolated down to shorter wavelengths. Currently, the problem of accurate extrapolation of visible data down to the UV spectral range is not solved completely, and there are few available measurements. The major difficulty is insufficient correlation between photosynthetic and photoprotective pigments of phytoplankton absorbing in the visible and UV respectively. We propose to empirically parameterize seawater absorption in the UV on a basis of available data sets of bio-optical measurements from a variety of ocean waters. Another problem is the lack of reliable data on pure seawater absorption in the UV. Laboratory measurements of the UV absorption of both pure water and pure seawater are required.

Response of Two Plant Species to Two Ultraviolet-B Radiation Regimes

NASA Technical Reports Server (NTRS)

Levy, Daniel L.; Skiles, J. W.; Peterson, David (Technical Monitor)

1996-01-01

The depleted stratospheric ozone layer has been directly linked to increased levels of ultraviolet radiation at the earth's surface. It is important to understand what effect this will have on plants. We tested the hypothesis that in response to increased UV-B radiation (280-320 man), soybean (Glycine max Merrill) and alfalfa (Mercado Saliva L.) would produce higher concentrations of flavonoids than plants screened from UV-B. Soybean and alfalfa plants were grown successively in a growth chamber that provided UV-B radiation intensities 45% above summer field levels. A wooden frame was used to suspend mylar-D film over one group of plants and mono-acetate film over another group. Mylar is opaque in the 280-316 nm range, and acetate absorbs most radiation from 280-290 nm and then reduces intensities in the 290-320 nm range by roughly 15%. Leaf chlorophyll concentration was determined with a Minolta SPAD-502 chlorophyll meter; the BRAD meter was calibrated with N,N- extractions. Flavonoids were extracted with an acidified methanol/water solution. Soybean grown under the acetate treatment showed 26% smaller internodal lengths and higher concentrations of flavonoids compared to plants grown under mylar. Significant results for alfalfa included 22% greater leaf flavonoid concentration under acetate, 14% greater leaf chlorophyll concentration under mylar, and 32% greater above-ground biomass under mylar. We found that increased UV-B radiation leads to increased production of UV-B absorbing compounds (i.e. flavonoids) in soybean and alfalfa leaves. This suggests that a protective mechanism in these plants is triggered by UV-B. In response, flavonoids are produced that absorb UV-B, and consequently decrease potentially damaging effects to the plants. In addition, we hypothesize that this flavonoid protection mechanism saturates at certain UV-B intensities.

Inferring ultraviolet anatomical exposure patterns while distinguishing the relative contribution of radiation components

NASA Astrophysics Data System (ADS)

Vuilleumier, Laurent; Milon, Antoine; Bulliard, Jean-Luc; Moccozet, Laurent; Vernez, David

2013-05-01

Exposure to solar ultraviolet (UV) radiation is the main causative factor for skin cancer. UV exposure depends on environmental and individual factors, but individual exposure data remain scarce. While ground UV irradiance is monitored via different techniques, it is difficult to translate such observations into human UV exposure or dose because of confounding factors. A multi-disciplinary collaboration developed a model predicting the dose and distribution of UV exposure on the basis of ground irradiation and morphological data. Standard 3D computer graphics techniques were adapted to develop a simulation tool that estimates solar exposure of a virtual manikin depicted as a triangle mesh surface. The amount of solar energy received by various body locations is computed for direct, diffuse and reflected radiation separately. Dosimetric measurements obtained in field conditions were used to assess the model performance. The model predicted exposure to solar UV adequately with a symmetric mean absolute percentage error of 13% and half of the predictions within 17% range of the measurements. Using this tool, solar UV exposure patterns were investigated with respect to the relative contribution of the direct, diffuse and reflected radiation. Exposure doses for various body parts and exposure scenarios of a standing individual were assessed using erythemally-weighted UV ground irradiance data measured in 2009 at Payerne, Switzerland as input. For most anatomical sites, mean daily doses were high (typically 6.2-14.6 Standard Erythemal Dose, SED) and exceeded recommended exposure values. Direct exposure was important during specific periods (e.g. midday during summer), but contributed moderately to the annual dose, ranging from 15 to 24% for vertical and horizontal body parts, respectively. Diffuse irradiation explained about 80% of the cumulative annual exposure dose.

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

NASA Technical Reports Server (NTRS)

Herman, Jay R.

2010-01-01

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

Performance results from in-flight commissioning of the Juno Ultraviolet Spectrograph (Juno-UVS)

NASA Astrophysics Data System (ADS)

Greathouse, T. K.; Gladstone, G. R.; Davis, M. W.; Slater, D. C.; Versteeg, M. H.; Persson, K. B.; Walther, B. C.; Winters, G. S.; Persyn, S. C.; Eterno, J. S.

2013-09-01

We present a description of the Juno ultraviolet spectrograph (Juno-UVS) and results from its in-flight commissioning performed between December 5th and 13th 2011 and its first periodic maintenance between October 10th and 12th 2012. Juno-UVS is a modest power (9.0 W) ultraviolet spectrograph based on the Alice instruments now in flight aboard the European Space Agency's Rosetta spacecraft, NASA's New Horizons spacecraft, and the LAMP instrument aboard NASA's Lunar Reconnaissance Orbiter. However, unlike the other Alice spectrographs, Juno-UVS sits aboard a spin stabilized spacecraft. The Juno-UVS scan mirror allows for pointing of the slit approximately +/-30° from the spacecraft spin plane. This ability gives Juno-UVS access to half the sky at any given spacecraft orientation. The planned 2 rpm spin rate for the primary mission results in integration times per 0.2° spatial resolution element per spin of only ~17 ms. Thus, for calibration purposes, data were retrieved from many spins and then remapped and co-added to build up exposure times on bright stars to measure the effective area, spatial resolution, scan mirror pointing positions, etc. The primary job of Juno-UVS will be to characterize Jupiter's UV auroral emissions and relate them to in-situ particle measurements. The ability to point the slit will make operations more flexible, allowing Juno-UVS to observe the atmospheric footprints of magnetic field lines through which Juno flies, giving a direct connection between energetic particle measurements on the spacecraft and the far-ultraviolet emissions produced by Jupiter's atmosphere in response to those particles.

Development of deep-ultraviolet metal vapor lasers

NASA Astrophysics Data System (ADS)

Sabotinov, Nikola V.

2004-06-01

Deep ultraviolet laser generation is of great interest in connection with both the development of new industrial technologies and applications in medicine, biology, chemistry, etc. The development of metal vapor UV lasers oscillating in the pulsed mode with high pulse repetition frequencies and producing high average output powers is of particular interest for microprocessing of polymers, photolithography and fluorescence applications. At present, metal vapor lasers generate deep-UV radiation on the base of two methods. The first method is non-linear conversion of powerful laser generation from the visible region into the deep ultraviolet region. The second method is direct UV laser action on ion and atomic transitions of different metals.

Foraging behavior of honey bees (hymenoptera: Apidae) on Brassica nigra and B. rapa grown under simulated ambient and enhanced UV-B radiation

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

Collins, S.A.; Robinson, G.E.; Conner, J.K.

Two species of mustard, Brassica nigra and B. rapa, were grown under simulated ambient and enhanced ultraviolet-B (UV-B) radiation and exposed to pollinators, Apis mellifera L. Observations were made to determine whether UV-B-induced changes in these plants affected pollinator behavior. Total duration of the foraging trip, number of flowers visited, foraging time per flower, search time per flower, total amount of pollen collected, and pollen collected per flower were measured. There were no significant differences between UV-B treatments in any of the behaviors measured or in any of the pollen measurements. These results suggest that increases in the amount ofmore » solar UV-B reaching the earth`s surface may not have a negative effect on the relationship between these members of the genus Brassica and their honey bee pollinators. 28 refs., 2 figs., 1 tab.« less

Rapid modulation of ultraviolet shielding in plants is influenced by solar ultraviolet radiation and linked to alterations in flavonoids.

PubMed

Barnes, Paul W; Tobler, Mark A; Keefover-Ring, Ken; Flint, Stephan D; Barkley, Anne E; Ryel, Ronald J; Lindroth, Richard L

2016-01-01

The accumulation of ultraviolet (UV)-absorbing compounds (flavonoids and related phenylpropanoids) and the resultant decrease in epidermal UV transmittance (TUV ) are primary protective mechanisms employed by plants against potentially damaging solar UV radiation and are critical components of the overall acclimation response of plants to changing solar UV environments. Whether plants can adjust this UV sunscreen protection in response to rapid changes in UV, as occurs on a diurnal basis, is largely unexplored. Here, we use a combination of approaches to demonstrate that plants can modulate their UV-screening properties within minutes to hours, and these changes are driven, in part, by UV radiation. For the cultivated species Abelmoschus esculentus, large (30-50%) and reversible changes in TUV occurred on a diurnal basis, and these adjustments were associated with changes in the concentrations of whole-leaf UV-absorbing compounds and several quercetin glycosides. Similar results were found for two other species (Vicia faba and Solanum lycopersicum), but no such changes were detected in Zea mays. These findings reveal a much more dynamic UV-protection mechanism than previously recognized, raise important questions concerning the costs and benefits of UV-protection strategies in plants and have practical implications for employing UV to enhance crop vigor and quality in controlled environments. © 2015 John Wiley & Sons Ltd.

Graphene Oxide Transparent Hybrid Film and Its Ultraviolet Shielding Property.

PubMed

Xie, Siyuan; Zhao, Jianfeng; Zhang, Bowu; Wang, Ziqiang; Ma, Hongjuan; Yu, Chuhong; Yu, Ming; Li, Linfan; Li, Jingye

2015-08-19

Herein, we first reported a facile strategy to prepare functional Poly(vinyl alcohol) (PVA) hybrid film with well ultraviolet (UV) shielding property and visible light transmittance using graphene oxide nanosheets as UV-absorber. The absorbance of ultraviolet light at 300 nm can be up to 97.5%, while the transmittance of visible light at 500 nm keeps 40% plus. This hybrid film can protect protein from UVA light induced photosensitive damage, remarkably.

Effect of UV-ozone treatment on poly(dimethylsiloxane) membranes: surface characterization and gas separation performance.

PubMed

Fu, Ywu-Jang; Qui, Hsuan-zhi; Liao, Kuo-Sung; Lue, Shingjiang Jessie; Hu, Chien-Chieh; Lee, Kueir-Rarn; Lai, Juin-Yih

2010-03-16

A thin SiO(x) selective surface layer was formed on a series of cross-linked poly(dimethylsiloxane) (PDMS) membranes by exposure to ultraviolet light at room temperature in the presence of ozone. The conversion of the cross-linked polysiloxane to SiO(x) was monitored by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray (EDX) microanalysis, contact angle analysis, and atomic force microscopy (AFM). The conversion of the cross-linked polysiloxane to SiO(x) increased with UV-ozone exposure time and cross-linking agent content, and the surface possesses highest conversion. The formation of a SiO(x) layer increased surface roughness, but it decreased water contact angle. Gas permeation measurements on the UV-ozone exposure PDMS membranes documented interesting gas separation properties: the O(2) permeability of the cross-linked PDMS membrane before UV-ozone exposure was 777 barrer, and the O(2)/N(2) selectivity was 1.9; after UV-ozone exposure, the permeability decreased to 127 barrer while the selectivity increased to 5.4. The free volume depth profile of the SiO(x) layer was investigated by novel slow positron beam. The results show that free volume size increased with the depth, yet the degree of siloxane conversion to SiO(x) does not affect the amount of free volume.

Ultraviolet reflectance spectroscopy measurements of carbonaceous meteorites and planetary analog materials

NASA Astrophysics Data System (ADS)

Hibbitts, Charles A.; Stockstill-Cahill, Karen; Takir, Driss

2017-10-01

The compositions of airless solar system objects tell us about the origin and evolutionary processes that are responsible for the current state of our solar system and that shape our environment. Spectral reflectance measurements in the ultraviolet are being used more frequently for providing compositional information of airless solid surfaces. Most minerals absorb in the UV making studying surface composition both informative but also challenging [e.g. 1]. The UV region is sensitive to atomic and molecular electronic absorptions such as the ligand-metal charge transfer band that is present in oxides and silicates and the conduction band at vacuum UV wavelengths. At the JHU-APL, bidirectional UV reflectance measurements are obtained under vacuum using a McPherson monochrometer with a PMT detector to achieve measurements over the range from ~ 140 nm to ~ 570 nm. Sample temperature can also be controlled from ~ 100K to ~ 600K, which enables the exploring the interaction of water ice and other volatiles with refractory samples. We have measured the UV spectra of many carbonaceous chondrites, including Mokoia, Vigarano, Warrenton, Orgueil, SaU290, and Essebi. In addition to being dark, some also possess on OMCT band. We have also obtained IR measurement of these meteorites to explore possible correlations between their UV and IR spectral signatures. In addition, we have also measured the UV spectra of low water content lunar analog glasses and have found a correlation between the spectral nature of the OMCT band and the abundance of iron [3]. Also, the spectral signature of mineralic and adsorbed water in the UV has been investigated. While water-ice has a known strong absorption feature near 180 nm (e.g. 4], adsorbed molecular and disassociatively adsorbed OH appear to not be optically active in this spectral region [5]. References: [1] Wagner et al. (1987) Icarus, 69, 14-28.1987; [2] Cloutis et al. (2008) Icarus, 197, 321-347; [3] Greenspon et al. (2012), 43rd LPSC, 1659, 2490; [4] Hendrix, A. and C. J. Hansen (2008) Icarus, 193, 323-333; [5] Hibbitts, C.A. (2015) DPS #47, 215.05.

Correlation between excited d-orbital electron lifetime in polaron dynamics and coloration of WO3 upon ultraviolet exposure

NASA Astrophysics Data System (ADS)

Lee, Young-Ahn; Han, Seung-Ik; Rhee, Hanju; Seo, Hyungtak

2018-05-01

Polarons have been suggested to explain the mechanism of the coloration of WO3 induced by UV light. However, despite the many experimental results that support small polarons as a key mechanism, direct observation of the carrier dynamics of polarons have yet to be reported. Here, we investigate the correlation between the electronic structure and the coloration of WO3 upon exposure to UV light in 5% H2/N2 gas and, more importantly, reveal photon-induced excited d-electron generation/relaxation via the W5+ oxidation state. The WO3 is fabricated by radio-frequency magnetron sputtering. X-ray diffraction patterns show that prepared WO3 is amorphous. Optical bandgap of 3.1 eV is measured by UV-vis before and after UV light. The results of Fourier transform infrared and Raman exhibit pristine WO3 is formed with surface H2O. The colored WO3 shows reduced state of W5+ state (34.3 eV) by using X-ray photoelectron spectroscopy. The valence band maximum of WO3 after UV light in H2 is shifted from mid gap to shallow donor by using ultraviolet photoelectron spectroscopy. During the exploration of the carrier dynamics, pump (700 nm)-probe (1000 nm) spectroscopy at the femtosecond scale was used. The results indicated that electron-phonon relaxation of UV-irradiated WO3, which is the origin of the polaron-induced local surface plasmonic effect, is dominant, resulting in slow decay (within a few picoseconds); in contrast, pristine WO3 shows fast decay (less than a picosecond). Accordingly, the long photoinduced carrier relaxation is ascribed to the prolonged hot-carrier lifetime in reduced oxides resulting in a greater number of free d-electrons and, therefore, more interactions with the W5+ sub-gap states.

Effect of Lot Variability on Ultraviolet Radiation Inactivation Kinetics of Cryptosporidium parvum Oocysts

EPA Science Inventory

Numerous studies have demonstrated the efficiency of ultraviolet (UV) radiation for the inactivation of oocysts of Cryptosporidium parvum. In these studies inactivation is measured as reduction in oocysts. A primary goal is to estimate the UV radiation required to achiev...

LOW PRESSURE ULTRAVIOLET STUDIES FOR INACTIVIATION OF GIARDIA MURIS CYSTS

EPA Science Inventory

This research was initiated to confirm and expand the current database for the inactiviation of Giardia spp. using ultraviolet (UV) radiation. The path taken was to confirm earlier UV research that used excystation as the indication of viability. In this study, an in vitro excyst...

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

NASA Technical Reports Server (NTRS)

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

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

PubMed

Mok, Jungbin; Krotkov, Nickolay A; Arola, Antti; Torres, Omar; Jethva, Hiren; Andrade, Marcos; Labow, Gordon; Eck, Thomas F; Li, Zhanqing; Dickerson, Russell R; Stenchikov, Georgiy L; Osipov, Sergey; Ren, Xinrong

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, HO 2 , and RO 2 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.

Demonstration of UV LED versatility when paired with molded UV transmitting glass optics to produce unique irradiance patterns

NASA Astrophysics Data System (ADS)

Jasenak, Brian

2017-02-01

Ultraviolet light-emitting diode (UV LED) adoption is accelerating; they are being used in new applications such as UV curing, germicidal irradiation, nondestructive testing, and forensic analysis. In many of these applications, it is critically important to produce a uniform light distribution and consistent surface irradiance. Flat panes of fused quartz, silica, or glass are commonly used to cover and protect UV LED arrays. However, they don't offer the advantages of an optical lens design. An investigation was conducted to determine the effect of a secondary glass optic on the uniformity of the light distribution and irradiance. Glass optics capable of transmitting UV-A, UV-B, and UV-C wavelengths can improve light distribution, uniformity, and intensity. In this work, two simulation studies were created to illustrate distinct irradiance patterns desirable for potential real world applications. The first study investigates the use of a multi-UV LED array and optic to create a uniform irradiance pattern on the flat two dimensional (2D) target surface. The uniformity was improved by designing both the LED array and molded optic to produce a homogenous pattern. The second study investigated the use of an LED light source and molded optic to improve the light uniformity on the inside of a canister. The case study illustrates the requirements for careful selection of LED based on light distribution and subsequent design of optics. The optic utilizes total internal reflection to create optimized light distribution. The combination of the LED and molded optic showed significant improvement in uniformity on the inner surface of the canister. The simulations illustrate how the application of optics can significantly improve UV light distribution which can be critical in applications such as UV curing and sterilization.

Fine structural dependence of ultraviolet reflections in the King Penguin beak horn.

PubMed

Dresp, Birgitta; Langley, Keith

2006-03-01

The visual perception of many birds extends into the near-ultraviolet (UV) spectrum and ultraviolet is used by some to communicate. The beak horn of the King Penguin (Aptenodytes patagonicus) intensely reflects in the ultraviolet and this appears to be implicated in partner choice. In a preliminary study, we recently demonstrated that this ultraviolet reflectance has a structural basis, resulting from crystal-like photonic structures, capable of reflecting in the near-UV. The present study attempted to define the origin of the photonic elements that produce the UV reflectance and to better understand how the UV signal is optimized by their fine structure. Using light and electron microscopic analysis combined with new spectrophotometric data, we describe here in detail the fine structure of the entire King Penguin beak horn in addition to that of its photonic crystals. The data obtained reveal a one-dimensional structural periodicity within this tissue and demonstrate a direct relationship between its fine structure and its function. In addition, they suggest how the photonic structures are produced and how they are stabilized. The measured lattice dimensions of the photonic crystals, together with morphological data on its composition, permit predictions of the wavelength of reflected light. These correlate well with experimentally observed values. The way the UV signal is optimized by the fine structure of the beak tissue is discussed with regard to its putative biological role.

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

NASA Astrophysics Data System (ADS)

Bai, Jianhui; Wang, Gengchen

2003-09-01

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

Solar glint suppression in compact planetary ultraviolet spectrographs

NASA Astrophysics Data System (ADS)

Davis, Michael W.; Cook, Jason C.; Grava, Cesare; Greathouse, Thomas K.; Gladstone, G. Randall; Retherford, Kurt D.

2015-08-01

Solar glint suppression is an important consideration in the design of compact photon-counting ultraviolet spectrographs. Southwest Research Institute developed the Lyman Alpha Mapping Project for the Lunar Reconnaissance Orbiter (launch in 2009), and the Ultraviolet Spectrograph on Juno (Juno-UVS, launch in 2011). Both of these compact spectrographs revealed minor solar glints in flight that did not appear in pre-launch analyses. These glints only appeared when their respective spacecraft were operating outside primary science mission parameters. Post-facto scattered light analysis verifies the geometries at which these glints occurred and why they were not caught during ground testing or nominal mission operations. The limitations of standard baffle design at near-grazing angles are discussed, as well as the importance of including surface scatter properties in standard stray light analyses when determining solar keep-out efficiency. In particular, the scattered light analysis of these two instruments shows that standard "one bounce" assumptions in baffle design are not always enough to prevent scattered sunlight from reaching the instrument focal plane. Future builds, such as JUICE-UVS, will implement improved scattered and stray light modeling early in the design phase to enhance capabilities in extended mission science phases, as well as optimize solar keep out volume.

Global change and biological soil crusts: Effects of ultraviolet augmentation under altered precipitation regimes and nitrogen additions

USGS Publications Warehouse

Belnap, J.; Phillips, S.L.; Flint, S.; Money, J.; Caldwell, M.

2008-01-01

Biological soil crusts (BSCs), a consortium of cyanobacteria, lichens, and mosses, are essential in most dryland ecosystems. As these organisms are relatively immobile and occur on the soil surface, they are exposed to high levels of ultraviolet (UV) radiation and atmospheric nitrogen (N) deposition, rising temperatures, and alterations in precipitation patterns. In this study, we applied treatments to three types of BSCs (early, medium, and late successional) over three time periods (spring, summer, and spring-fall). In the first year, we augmented UV and altered precipitation patterns, and in the second year, we augmented UV and N. In the first year, with average air temperatures, we saw little response to our treatments except quantum yield, which was reduced in dark BSCs during one of three sample times and in Collema BSCs two of three sample times. There was more response to UV augmentation the second year when air temperatures were above average. Declines were seen in 21% of the measured variables, including quantum yield, chlorophyll a, UV-protective pigments, nitrogenase activity, and extracellular polysaccharides. N additions had some negative effects on light and dark BSCs, including the reduction of quantum yield, ??-carotene, nitrogenase activity, scytonemin, and xanthophylls. N addition had no effects on the Collema BSCs. When N was added to samples that had received augmented UV, there were only limited effects relative to samples that received UV without N. These results indicate that the negative effect of UV and altered precipitation on BSCs will be heightened as global temperatures increase, and that as their ability to produce UV-protective pigments is compromised, physiological functioning will be impaired. N deposition will only ameliorate UV impacts in a limited number of cases. Overall, increases in UV will likely lead to lowered productivity and increased mortality in BSCs through time, which, in turn, will reduce their ability to contribute to the stability and fertility of soils in dryland regions. ?? 2008 The Authors Journal compilation ?? 2008 Blackwell Publishing Ltd.

Evaluating Ultraviolet Radiation Exposures Determined from TOMS Satellite Data at Sites of Amphibian Declines in Central and South America

NASA Technical Reports Server (NTRS)

Middleton, Elizabeth M.; Smith, David E. (Technical Monitor)

2000-01-01

Many amphibian species have experienced substantial population declines, or have disappeared altogether, during the last several decades at a number of amphibian census sites in Central and South America. This study addresses the use of satellite-derived trends in solar ultraviolet-B (UV-B; 280-320 nm) radiation exposures at these sites over the last two decades, and is intended to demonstrate a role for satellite observations in determining whether UV-B radiation is a contributing factor in amphibian declines. UV-B radiation levels at the Earth's surface were derived from the Total Ozone Mapping Spectrometer (TOMS) satellite data, typically acquired daily since 1979. These data were used to calculate the daily erythemal (sunburning) UV-B, or UV-B(sub ery), exposures at the latitude, longitude, and elevation of each of 20 census sites. The annually averaged UV-B(sub ery) dose, as well as the maximum values, have been increasing in both Central and South America, with higher levels received at the Central American sites. The annually averaged UV-B(sub ery) exposures increased significantly from 1979-1998 at all 11 Central American sites examined (r(exp 2) = 0.60 - 0.79; P<=0.015), with smaller but significant increases at five of the nine South American sites (r(exp 2) = 0.24-0.42; P<=0.05). The contribution of the highest UV-B(sub ery) exposure levels (>= 6750 J/sq m*d) to the annual UV-B(sub ery) total has increased from approx. 5% to approx. 15% in Central America over the 19 year period, but actual daily exposures for each species are unknown. Synergy among UV-B radiation and other factors, especially those associated with alterations of water chemistry (e.g., acidification) in aqueous habitats is discussed. These findings justify further research concerning whether UV-B(sub ery) radiation plays a role in amphibian population declines and extinctions.

Surface XPS characterization of NiTi shape memory alloy after advanced oxidation processes in UV/H 2O 2 photocatalytic system

NASA Astrophysics Data System (ADS)

Wang, R. M.; Chu, C. L.; Hu, T.; Dong, Y. S.; Guo, C.; Sheng, X. B.; Lin, P. H.; Chung, C. Y.; Chu, P. K.

2007-08-01

Surface structure of NiTi shape memory alloy (SMA) was modified by advanced oxidation processes (AOP) in an ultraviolet (UV)/H 2O 2 photocatalytic system, and then systematically characterized with x-ray photoelectron spectroscopy (XPS). It is found that the AOP in UV/H 2O 2 photocatalytic system leads to formation of titanium oxides film on NiTi substrate. Depth profiles of O, Ni and Ti show such a film possesses a graded interface structure to NiTi substrate and there is no intermediate Ni-rich layer like that produced in conventional high temperature oxidation. Except TiO 2 phase, some titanium suboxides (TiO, Ti 2O 3) may also exist in the titanium oxides film. Oxygen mainly presents in metal oxides and some chemisorbed water and OH - are found in titanium oxides film. Ni nearly reaches zero on the upper surface and relatively depleted in the whole titanium oxides film. The work indicates the AOP in UV/H 2O 2 photocatalytic system is a promising way to favor the widespread application of biomedical NiTi SMA by improving its biocompatibility.

Invisible ink mark detection in the visible spectrum using absorption difference.

PubMed

Lee, Joong; Kong, Seong G; Kang, Tae-Yi; Kim, Byounghyun; Jeon, Oc-Yeub

2014-03-01

One of popular techniques in gambling fraud involves the use of invisible ink marks printed on the back surface of playing cards. Such covert patterns are transparent in the visible spectrum and therefore invisible to unaided human eyes. Invisible patterns can be made visible with ultraviolet (UV) illumination or a CCD camera installed with an infrared (IR) filter depending on the type of ink materials used. Cheating gamers often wear contact lenses or eyeglasses made of IR or UV filters to recognize the secret marks on the playing cards. This paper presents an image processing technique to reveal invisible ink patterns in the visible spectrum without the aid of special equipment such as UV lighting or IR filters. A printed invisible ink pattern leaves a thin coating on the surface with different refractive index for different wavelengths of light, which results in color dispersion or absorption difference. The proposed method finds the differences of color components caused by absorption difference to detect invisible ink patterns on the surface. Experiment results show that the proposed scheme is effective for both UV-active and IR-active invisible ink materials. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Newer views of the Moon: Comparing spectra from Clementine and the Moon Mineralogy Mapper

USGS Publications Warehouse

Kramer, G.Y.; Besse, S.; Nettles, J.; Combe, J.-P.; Clark, R.N.; Pieters, C.M.; Staid, M.; Malaret, E.; Boardman, J.; Green, R.O.; Head, J.W.; McCord, T.B.

2011-01-01

The Moon Mineralogy Mapper (M3) provided the first global hyperspectral data of the lunar surface in 85 bands from 460 to 2980 nm. The Clementine mission provided the first global multispectral maps the lunar surface in 11 spectral bands across the ultraviolet-visible (UV-VIS) and near-infrared (NIR). In an effort to understand how M3 improves our ability to analyze and interpret lunar data, we compare M3 spectra with those from Clementine's UV-VIS and NIR cameras. The Clementine mission provided the first global multispectral maps the lunar surface in 11 spectral bands across the UV-VIS and NIR. We have found that M3 reflectance values are lower across all wavelengths compared with albedos from both of Clementine's UV-VIS and NIR cameras. M3 spectra show the Moon to be redder, that is, have a steeper continuum slope, than indicated by Clementine. The 1 m absorption band depths may be comparable between the instruments, but Clementine data consistently exhibit shallower 2 m band depths than M 3. Absorption band minimums are difficult to compare due to the significantly different spectral resolutions. Copyright 2011 by the American Geophysical Union.

Newer views of the Moon: Comparing spectra from Clementineand the Moon Mineralogy Mapper

USGS Publications Warehouse

Georgiana Y. Kramer,; Sebastian Besse,; Nettles, Jeff; Jean-Philippe Combe,; Clark, Roger N.; Pieters, Carle M.; Matthew Staid,; Joseph Boardman,; Robert Green,; McCord, Thomas B.; Malaret, Erik; Head, James W.

2011-01-01

The Moon Mineralogy Mapper (M3) provided the first global hyperspectral data of the lunar surface in 85 bands from 460 to 2980 nm. The Clementine mission provided the first global multispectral maps the lunar surface in 11 spectral bands across the ultraviolet-visible (UV-VIS) and near-infrared (NIR). In an effort to understand how M3 improves our ability to analyze and interpret lunar data, we compare M3 spectra with those from Clementine's UV-VIS and NIR cameras. The Clementine mission provided the first global multispectral maps the lunar surface in 11 spectral bands across the UV-VIS and NIR. We have found that M3 reflectance values are lower across all wavelengths compared with albedos from both of Clementine's UV-VIS and NIR cameras. M3 spectra show the Moon to be redder, that is, have a steeper continuum slope, than indicated by Clementine. The 1 μm absorption band depths may be comparable between the instruments, but Clementine data consistently exhibit shallower 2 μm band depths than M3. Absorption band minimums are difficult to compare due to the significantly different spectral resolutions.

Assessment of 10 Year Record of Aerosol Optical Depth from OMI UV Observations

NASA Technical Reports Server (NTRS)

Ahn, Changwoo; Torres, Omar; Jethva, Hiren

2014-01-01

The Ozone Monitoring Instrument (OMI) onboard the EOS-Aura satellite provides information on aerosol optical properties by making use of the large sensitivity to aerosol absorption in the near-ultraviolet (UV) spectral region. Another important advantage of using near UV observations for aerosol characterization is the low surface albedo of all terrestrial surfaces in this spectral region that reduces retrieval errors associated with land surface reflectance characterization. In spite of the 13 × 24 square kilometers coarse sensor footprint, the OMI near UV aerosol algorithm (OMAERUV) retrieves aerosol optical depth (AOD) and single-scattering albedo under cloud-free conditions from radiance measurements at 354 and 388 nanometers. We present validation results of OMI AOD against space and time collocated Aerosol Robotic Network measured AOD values over multiple stations representing major aerosol episodes and regimes. OMAERUV's performance is also evaluated with respect to those of the Aqua-MODIS Deep Blue and Terra-MISR AOD algorithms over arid and semi-arid regions in Northern Africa. The outcome of the evaluation analysis indicates that in spite of the "row anomaly" problem, affecting the sensor since mid-2007, the long-term aerosol record shows remarkable sensor stability.

QUALITY ASSURANCE AND SITE MANAGEMENT FOR PRIMENET AND URBAN ULTRAVIOLET RADIATION RESEARCH MONITORING PROGRAM.

EPA Science Inventory

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

Extending the use of ultraviolet light for fruit quality sorting in citrus packinghouses

USDA-ARS?s Scientific Manuscript database

Illumination with ultraviolet light (UV) is commonly used in citrus packinghouses as a means to aid in the identification and removal of decayed oranges from the packline. This technique is effective because areas of decay strongly fluoresce under UV illumination. It was observed that oranges often ...

QUANTIFYING ULTRAVIOLET RADIATION DOSE RELATIVE TO WETLAND HABITAT VARIABLES FOR THE ASSESSMENT OF RISK TO AMPHIBIANS

EPA Science Inventory

Ultraviolet B radiation (UV-B) has increased globally over the last several decades due to reduction of stratospheric ozone. UV-B may also increase when climate change alters cloud cover, rainfall, and distributions of vegetation. In aquatic systems, these factors can also intera...

ASSESSING THE EFFECTIVENESS OF LOW PRESSURE ULTRAVIOLET LIGHT FOR INACTIVATING HELICOBACTER PYLORI

EPA Science Inventory

Three strains of Helicobacter pylori were exposed to ultraviolet (UV) light from a low-pressure source to determine log inactivation versus applied fluence. Results indicate that H. pylori is readily inactivated at UV fluences typically used in water treatment r...

Tailoring of TiO2 films by H2SO4 treatment and UV irradiation to improve anticoagulant ability and endothelial cell compatibility.

PubMed

Liao, Yuzhen; Li, Linhua; Chen, Jiang; Yang, Ping; Zhao, Ansha; Sun, Hong; Huang, Nan

2017-07-01

Surfaces with dual functions that simultaneously exhibit good anticoagulant ability and endothelial cell (EC) compatibility are desirable for blood contact materials. However, these dual functions have rarely been achieved by inorganic materials. In this study, titanium dioxide (TiO 2 ) films were treated by sulphuric acid (H 2 SO 4 ) and ultraviolet (UV) irradiation successively (TiO 2 H 2 SO 4 -UV), resulting in good anticoagulant ability and EC compatibility simultaneously. We found that UV irradiation improved the anticoagulant ability of TiO 2 films significantly while enhancing EC compatibility, though not significantly. The enhanced anticoagulant ability could be related to the oxidation of surface-adsorbed hydrocarbons and increased hydrophilicity. The H 2 SO 4 treatment improved the anticoagulant ability of TiO 2 films slightly, while UV irradiation improved the anticoagulant ability strongly. The enhanced EC compatibility could be related to the increased surface roughness and positive charges on the surface of the TiO 2 films. Furthermore, the time-dependent degradation of the enhanced EC compatibility and anticoagulant ability of TiO 2 H 2 SO 4 -UV was observed. In summary, TiO 2 H 2 SO 4 -UV expressed both excellent anticoagulant ability and good EC compatibility at the same time, which could be desirable for blood contact materials. However, the compatibility of TiO 2 H 2 SO 4 -UV with smooth muscle cells (SMCs) and macrophages was also improved. More effort is still needed to selectively improve EC compatibility on TiO 2 films for better re-endothelialization. Copyright © 2017 Elsevier B.V. All rights reserved.

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

NASA Technical Reports Server (NTRS)

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

1999-01-01

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

Large area ultraviolet photodetector on surface modified Si:GaN layers

NASA Astrophysics Data System (ADS)

Anitha, R.; R., Ramesh; Loganathan, R.; Vavilapalli, Durga Sankar; Baskar, K.; Singh, Shubra

2018-03-01

Unique features of semiconductor based heterostructured photoelectric devices have drawn considerable attention in the recent past. In the present work, large area UV photodetector has been fabricated utilizing interesting Zinc oxide microstructures on etched Si:GaN layers. The surface of Si:GaN layer grown by metal organic chemical vapor deposition method on sapphire has been modified by chemical etching to control the microstructure. The photodetector exhibits response to Ultraviolet light only. Optimum etching of Si:GaN was required to exhibit higher responsivity (0.96 A/W) and detectivity (∼4.87 × 109 Jones), the two important parameters for a photodetector. Present method offers a tunable functionality of photodetector through modification of top layer microstructure. A comparison with state of art materials has also been presented.

Artist concept of Solar Backscatter UV (SBUV) measurement technique on TIROS

NASA Technical Reports Server (NTRS)

1989-01-01

Artist concept titled OZONE MEASUREMENT TECHNIQUE shows how the Solar Backscatter Ultraviolet (UV) 2 (SBUV-2) on the National Oceanic and Atmospheric Administration's (NOAA's) TIROS satellites (NOAA-9 and NOAA-11) works. Ozone is derived from the 'SBUV' instrument from the ratio of the observed backscattered radiance to the solar irradiance in the ultraviolet. This is called the ultraviolet albedo. During STS-34 Shuttle Solar Backscatter Ultraviolet (SSBUV) instruments in Atlantis', Orbiter Vehicle (OV) 104's, payload bay (PLB) will calibrate the instruments onboard the TIROS satellites. SSBUV is managed by Goddard Space Flight Center (GSFC).

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

PubMed Central

Lando, Gabriela Albara; Marconatto, Letícia; Schrank, Augusto; Vainstein, Marilene Henning

2017-01-01

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. PMID:28718785

Callisto False Color

NASA Image and Video Library

1996-09-26

This false color picture of Callisto was taken by NASA's Voyager 2 on July 7, 1979 at a range of 1,094,666 kilometers (677,000 miles) and is centered on 11 degrees N and 171 degrees W. This rendition uses an ultraviolet image for the blue component. Because the surface displays regional contrast in UV, variations in surface materials are apparent. Notice in particular the dark blue haloes which surround bright craters in the eastern hemisphere. The surface of Callisto is the most heavily cratered of the Galilean satellites and resembles ancient heavily cratered terrains on the moon, Mercury and Mars. The bright areas are ejecta thrown out by relatively young impact craters. A large ringed structure, probably an impact basin, is shown in the upper left part of the picture. The color version of this picture was constructed by compositing black and white images taken through the ultraviolet, clear and orange filters. http://photojournal.jpl.nasa.gov/catalog/PIA00457

Biological effects of high ultraviolet radiation on early earth--a theoretical evaluation.

PubMed

Cockell, C S

1998-08-21

The surface of early Earth was exposed to both UVC radiation (< 280 nm) and higher doses of UVB (280-315 nm) compared with the surface of present day Earth. The degree to which this radiation environment acted as a selection pressure on organisms and biological systems has rarely been theoretically examined with respect to the biologically effective irradiances that ancient organisms would receive. Here action spectra for DNA inactivation and isolated chloroplast inhibition are used to estimate biologically effective irradiances on archean Earth. Comparisons are made with present day Earth. The theoretical estimations on the UV radiation screening required to protect DNA on archean Earth compare well with field and laboratory observations on protection strategies found in present day microbial communities. They suggest that many physical and biological methods may have been effective and would have allowed for the radiation of life even under the high UV radiation regimes of archean Earth. Such strategies would also have provided effective reduction of photoinhibition by UV radiation. The data also suggest that the UV regime on the surface of Mars is not a life limiting factor per se, although other environmental factors such as desiccation and low temperatures may contribute towards the apparent lack of a surface biota.

Far Ultraviolet Spectroscopic Explorer Observations of the Seyfert 1.5 Galaxy NGC 5548 in a Low State

NASA Technical Reports Server (NTRS)

Brotherton, M. S.; Green, R. F.; Kriss, G. A.; Oegerle, W.; Kaiser, M. E.; Zheng, W.; Hutchings, J. B.; Fisher, Richard R. (Technical Monitor)

2001-01-01

We present far-ultraviolet spectra of the Seyfert 1.5 galaxy NGC 5548 obtained in 2000 June with the Far Ultraviolet Spectroscopic Explorer (FUSE). Our data span the observed wavelength range 915-1185 A at a resolution of approximately 20 km s(exp -1). The spectrum shows a weak continuum and emission from O VI (lambda)(lambda)1032, 1038, C III (lambda)977, and He II (lambda)1085. The FUSE data were obtained when the AGN (Active Galactic Nuclei) was in a low state, which has revealed strong, narrow O VI emission lines. We also resolve intrinsic, associated absorption lines of O VI and the Lyman series. Several distinct kinematic components are present, spanning a velocity range of approximately 0 to -1300 km s(exp -1) relative to systemic, with kinematic structure similar to that seen in previous observations of longer wavelength ultraviolet (UV) lines. We explore the relationships between the far-UV (ultraviolet) absorbers and those seen previously in the UV and X-rays. We find that the high-velocity UV absorption component is consistent with being low-ionization, contrary to some previous claims, and is consistent with its non-detection in high-resolution X-ray spectra. The intermediate velocity absorbers, at -300 to -400 km s(exp -1), show H I and O VI column densities consistent with having contributions from both a high-ionization X-ray absorber and a low-ionization UV absorber. No single far-UV absorbing component can be solely identified with the X-ray absorber.

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

PubMed

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

2014-12-01

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

Ultraviolet reflectance spectroscopy measurements of planetary materials and their analogs

NASA Astrophysics Data System (ADS)

Hibbitts, C.; Stockstill-Cahill, K.

2017-12-01

The compositions of airless solar system objects tell us about the origin and evolutionary processes that are responsible for the current state of our solar system and that shape our environment. Spacecraft have obtained UV reflectance measurements of the surfaces of Mercury, the Moon, asteroids, comets, icy satellites, and Pluto from which composition is being inferred. Most minerals absorb in the UV making studying surface composition both informative but also challenging [e.g. 1]. The UV region is sensitive to atomic and molecular electronic absorptions such as the ligand-metal charge transfer band that is present in oxides and silicates and the conduction band at vacuum UV wavelengths. Unfortunately, limited laboratory reflectance measurements in the ultraviolet hampers the interpretation of some of these planetary UV reflectance datasets. However, several laboratory efforts have been developed [e.g. 2,3] to fill the need for laboratory UV measurements. These are difficult measurements to make, being complicated by the absorptive nature of the atmosphere, requiring measurements to be conducted under vacuum or over very short path lengths of a N2-purged system. Also, the lack of a widely accepted UV diffuse reflectance standard is problematic. At the JHU-APL, bidirectional UV reflectance measurements are obtained under vacuum from 140 nm to 570 nm. Sample temperature can be controlled from 100K to 600K, which enables the study of the interaction of water ice and other volatiles with the refractory samples. Results from our laboratory research include the development of a correlation between the spectral nature of the OMCT band and the abundance of iron in low water content lunar analog glasses [3]. Also, the spectral signature of water in the UV has been investigated. While water-ice has a known strong absorption feature near 180 nm [e.g. 4], adsorbed molecular and disassociatively adsorbed OH apparently are not optically active in this spectral region [5]. We have also measured the UV spectra of carbonaceous chondrites. References: [1] Wagner et al. (1987) Icarus, 69, 14-28.1987; [2] Cloutis et al. (2008) Icarus, 197, 321-347; [3] Greenspon et al. (2012), 43rd LPSC, 1659, 2490, [4] Hendrix, A. and C. J. Hansen (2008) Icarus, 193, 323-333; [5] Hibbitts, C.A. (2015) DPS #47, 215.05.

REPRESSOR OF ULTRAVIOLET-B PHOTOMORPHOGENESIS function allows efficient phototropin mediated ultraviolet-B phototropism in etiolated seedlings.

PubMed

Vanhaelewyn, Lucas; Schumacher, Paolo; Poelman, Dirk; Fankhauser, Christian; Van Der Straeten, Dominique; Vandenbussche, Filip

2016-11-01

Ultraviolet B (UV-B) light is a part of the solar radiation which has significant effects on plant morphology, even at low doses. In Arabidopsis, many of these morphological changes have been attributed to a specific UV-B receptor, UV resistance locus 8 (UVR8). Recent findings showed that next to phototropin regulated phototropism, UVR8 mediated signaling is able of inducing directional bending towards UV-B light in etiolated seedlings of Arabidopsis, in a phototropin independent manner. In this study, kinetic analysis of phototropic bending was used to evaluate the relative contribution of each of these pathways in UV-B mediated phototropism. Diminishing UV-B light intensity favors the importance of phototropins. Molecular and genetic analyses suggest that UV-B is capable of inducing phototropin signaling relying on phototropin kinase activity and regulation of NPH3. Moreover, enhanced UVR8 responses in the UV-B hypersensitive rup1rup2 mutants interferes with the fast phototropin mediated phototropism. Together the data suggest that phototropins are the most important receptors for UV-B induced phototropism in etiolated seedlings, and a RUP mediated negative feedback pathway prevents UVR8 signaling to interfere with the phototropin dependent response. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Ultraviolet protective properties of branded and unbranded sunglasses available in the Indian market in UV phototherapy chambers.

PubMed

Dongre, Atul M; Pai, Gitanjali G; Khopkar, Uday S

2007-01-01

Patients receiving phototherapy for various dermatoses are at increased risk of eye damage due to ultraviolet (UV) rays. They are prescribed UV protective sunglasses by dermatologists but their exact protecting effects are not known. To study the ultraviolet protective properties of branded and unbranded UV protective sunglasses available in the Indian market, in UV phototherapy chambers. Sixteen different branded and unbranded UV protective sunglasses were collected from two opticians in Mumbai. Baseline irradiance of the UV chamber was calculated by exposing the photosensitive probe of UV photometer in the chamber. Then, the photosensitive probe of the UV photometer was covered with the UV protective glass to be studied and irradiance was noted. Such readings were taken for each of the UV protective sunglasses. The percentage reduction in the UV rays' penetration of different UV protective sunglasses was calculated. Thirteen sunglasses provided > 80% reduction in UVA rays penetration, of which four were branded (out of the four branded studied) and nine were unbranded (out of the 12 unbranded studied). More than 70% reduction in UVB penetration was provided by 12 sunglasses, which included 10 unbranded and two branded sunglasses. All branded sunglasses provided good protection against UVA penetration, but UVB protection provided by both branded and unbranded sunglasses was not satisfactory. A few unbranded sunglasses had poor efficacy for UVA and UVB spectra; one branded glass had poor efficacy for protection against the UVB spectrum. The efficacy of sunglasses used for phototherapy should be assessed before use.

The Solar Ultraviolet Environment at the Ocean.

PubMed

Mobley, Curtis D; Diffey, Brian L

2018-05-01

Atmospheric and oceanic radiative transfer models were used to compute spectral radiances between 285 and 400 nm onto horizontal and vertical plane surfaces over water. The calculations kept track of the contributions by the sun's direct beam, by diffuse-sky radiance, by radiance reflected from the sea surface and by water-leaving radiance. Clear, hazy and cloudy sky conditions were simulated for a range of solar zenith angles, wind speeds and atmospheric ozone concentrations. The radiances were used to estimate erythemal exposures due to the sun and sky, as well as from radiation reflected by the sea surface and backscattered from the water column. Diffuse-sky irradiance is usually greater than direct-sun irradiance at wavelengths below 330 nm, and reflected and water-leaving irradiance accounts for <20% of the UV exposure on a vertical surface. Total exposure depends strongly on solar zenith angle and azimuth angle relative to the sun. Sea surface roughness affects the UV exposures by only a few percent. For very clear waters and the sun high in the sky, the UV index within the water can be >10 at depths down to two meters and >6 down to 5 m. © 2018 The American Society of Photobiology.

On-chip micropatterning of plastic (cylic olefin copolymer, COC) microfluidic channels for the fabrication of biomolecule microarrays using photografting methods.

PubMed

Pu, Qiaosheng; Oyesanya, Olufemi; Thompson, Bowlin; Liu, Shantang; Alvarez, Julio C

2007-01-30

This paper reports on the surface modification of plastic microfluidic channels to prepare different biomolecule micropatterns using ultraviolet (UV) photografting methods. The linkage chemistry is based upon UV photopolymerization of acryl monomers to generate thin films (0.01-6 microm) chemically linked to the organic backbone of the plastic surface. The commodity thermoplastic, cyclic olefin copolymer (COC) was selected to build microfluidic chips because of its significant UV transparency and easiness for microfabrication by molding techniques. Once the polyacrylic films were grafted on the COC surface using photomasks, micropatterns of proteins, DNA, and biotinlated conjugates were readily obtained by surface chemical reactions in one or two subsequent steps. The thickness of the photografted films can be tuned from several nanometers up to several micrometers, depending on the reaction conditions. The micropatterned films can be prepared inside the microfluidic channel (on-chip) or on open COC surfaces (off-chip) with densities of functional groups about 10(-7) mol/cm2. Characterization of these films was performed by attenuated-total-reflectance IR spectroscopy, fluorescence microscopy, profilometry, atomic force microscopy, and electrokinetic methods.

Violet light causes photodegradation of wood beyond the zone affected by ultraviolet radiation

Treesearch

Yutaka Kataoka; Makoto Kiguchi; R. Sam Williams; Philip D. Evans

2007-01-01

The limited penetration of wood by light explains why the weathering of wood exposed outdoors is a surface phenomenon. Wood is rapidly degraded by short-wave-length UV radiation, but the penetration of light into wood is positively correlated with its wavelength. Hence, subsurface degradation is likely to be caused by longer-wavelength light that still has sufficient...

Observations of Scorpius X-1 with IUE - Ultraviolet results from a multiwavelength campaign

NASA Technical Reports Server (NTRS)

Vrtilek, S. D.; Raymond, J. C.; Penninx, W.; Verbunt, F.; Hertz, P.

1991-01-01

IUE UV results are presented for the low-mass X-ray binary Sco X-1. Models that predict UV continuum emission from the X-ray-heated surface from the companion star and from an X-ray illuminated accretion disk are adjusted for parameters intrinsic to Sco X-1, and fitted to the data. X-ray heating is found to be the dominant source of UV emission; the mass-accretion rate increases monotonically along the 'Z-shaped' curve in an X-ray color-color diagram. UV emission lines from He, C, N, O, and Si were detected; they all increase in intensity from the HB to the FB state. A model in which emission lines are due to outer-disk photoionization by the X-ray source is noted to give good agreement with line fluxes observed in each state.

Optimization of droplets for UV-NIL using coarse-grain simulation of resist flow

NASA Astrophysics Data System (ADS)

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.

Natural dyeing and UV protection of plasma treated cotton

NASA Astrophysics Data System (ADS)

Gorjanc, Marija; Mozetič, Miran; Vesel, Alenka; Zaplotnik, Rok

2018-03-01

Raw cotton fabrics have been exposed to low-pressure non-equilibrium gaseous plasma to improve the adsorption of natural dyes as well as ultraviolet (UV) protection factor. Plasma created in a glass tube by an electrodeless radiofrequency (RF) discharge was created either in oxygen or ammonia at the pressure of 50 Pa to stimulate formation of oxygen and nitrogen groups, respectively. The type and concentration of functional groups was determined by X-ray photoelectron spectroscopy (XPS) and morphological modifications by scanning electron microscopy (SEM). The colour yield for curcumin dye was improved significantly for samples treated with ammonia plasma what was explained by bonding of the dye to surface of amino groups. Contrary, the yield decreased when oxygen plasma treatment was applied due to the negatively charged surface that repels the negatively charged dye molecules. The effect was even more pronounced when using green tea extract as the colouring agent. The colour difference between the untreated and ammonia plasma treated sample increased linearly with plasma treatment time reaching the factor of 3.5 for treatment time of 300 s. The ultraviolet protection factor (UPF) was over 50 indicating excellent protection due to improved adsorption of the dye on the ammonia plasma treated samples.

Intercalation of anionic organic ultraviolet ray absorbers into layered zinc hydroxide nitrate.

PubMed

Cursino, Ana Cristina Trindade; Gardolinski, José Eduardo Ferreira da Costa; Wypych, Fernando

2010-07-01

Layered zinc hydroxide nitrate (ZHN) was synthesized and nitrate ions were topotactically exchanged with three different anionic species of commercial organic ultraviolet (UV) ray absorbers: 2-mercaptobenzoic acid, 2-aminobenzoic acid, and 4-aminobenzoic acid. The exchange reactions were confirmed by X-ray powder diffraction (XRPD), Fourier transform infrared spectroscopy (FTIR), ultraviolet visible (UV-Vis) spectroscopy, and thermal analysis (thermogravimetry, TGA, and differential thermal analysis, DTA). In all the anionic exchanged products, evidence of grafting of the organic species onto the inorganic matrix was obtained. In general, after intercalation/grafting, the UV absorption ability was improved in relation to the use of the parent organic material, showing that layered hydroxide salts (LHS) can be good alternative matrixes for the immobilization of organic species with UV-blocking properties in cosmetic products. Copyright 2010 Elsevier Inc. All rights reserved.

Effects of long-duration exposure on optical system components

NASA Technical Reports Server (NTRS)

Harvey, Gale A.

1991-01-01

The optical materials and UV detectors experiment (SOO50-1) was a set of 18 optical windows, filters, and ultraviolet detectors. The optical specimens were all retrieved in excellent condition. No delamination or blistering of the filters occurred. No discoloration of the optical window materials occurred, but the MgF2 window did experience roughing. The most notable degradation of the optics were the deposition of an organic film on the exposed surfaces. The film absorption was measured using a Fourier transform infrared spectrometer and a UV spectrometer. The 6 percent absorption at 3.4 microns corresponds to about 100 mgm/sq ft of organic film. The UV absorption was almost 100 percent at 200 nm and about 50 percent at 380 nm.

Preharvest UV-C radiation influences physiological, biochemical, and transcriptional changes in strawberry cv. Camarosa.

PubMed

de Oliveira, Isadora Rubin; Crizel, Giseli Rodrigues; Severo, Joseana; Renard, Catherine M G C; Chaves, Fabio Clasen; Rombaldi, Cesar Valmor

2016-11-01

Ultraviolet C (UV-C) radiation is known for preventing fungal decay and enhancing phytochemical content in fruit when applied postharvest. However, limited knowledge is available regarding fruit responses to preharvest application of UV-C radiation. Thus, the effects of UV-C radiation on photosynthetic efficiency, dry matter accumulation and partitioning, fruit yield and decay, phytochemical content, and relative transcript accumulation of genes associated with these metabolic pathways were monitored in strawberry (Fragaria x ananassa Duch.) cv. Camarosa. A reduction in photosynthetic efficiency was followed by a decrease in light harvesting complex LhcIIb-1 mRNA accumulation as well as a decrease in yield per plant. Phenylalanine ammonia lyase activity, phenolic, anthocyanin, and L-ascorbic acid contents were higher in UV-C treated fruit. In addition, preharvest UV-C treatment reduced microorganism incidence in the greenhouse and on the fruit surface, increased the accumulation of β-1,3-Gluc and PR-1 mRNA, and prevented fruit decay. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Protective effects of platinum nanoparticles against UV-light-induced epidermal inflammation.

PubMed

Yoshihisa, Yoko; Honda, Ayumi; Zhao, Qing-Li; Makino, Teruhiko; Abe, Riichiro; Matsui, Kotaro; Shimizu, Hiroshi; Miyamoto, Yusei; Kondo, Takashi; Shimizu, Tadamichi

2010-11-01

Intracellular reactive oxygen species (ROS) and apoptosis play important roles in the ultraviolet (UV)-induced inflammatory responses in the skin. Metal nanoparticles have been developed to increase the catalytic activity of metals, which is because of the large surface area of smaller particles. Platinum nanoparticles (nano-Pt) protected by poly acrylic acid were manufactured by reduction with ethanol. A marked increase in ROS production was observed in UV-treated HaCaT keratinocytes cell lines, while a decrease in ROS production was observed in nano-Pt-treated cells. Pretreatment of the cells with nano-Pt also caused a significant inhibition of UVB- and UVC-induced apoptosis. Furthermore, we found that mice treated with nano-Pt gel prior to UV irradiation showed significant inhibition of UVB-induced inflammation and UVA-induced photoallergy compared to UV-irradiated control mice. These results suggest that nano-Pt effectively protects against UV-induced inflammation by decreasing ROS production and inhibiting apoptosis in keratinocytes. © 2010 John Wiley & Sons A/S.

Solar UV dose patterns in Italy.

PubMed

Meloni, D; Casale, G R; Siani, A M; Palmieri, S; Cappellani, F

2000-06-01

Since 1992 solar ultraviolet (UV) spectral irradiance (290-325 nm) has been measured at two Italian stations of Rome (urban site) and Ispra (semirural site) using Brewer spectrophotometry. The data collected under all sky conditions, are compared with the output of a sophisticated radiative transfer model (System for Transfer of Atmospheric Radiation--STAR model). The STAR multiple scattering scheme is able to cope with all physical processes relevant to the UV transfer through the atmosphere. The experience so far acquired indicates that, in spite of the unavoidable uncertainties in the input parameters (ozone, aerosol, surface albedo, pressure, temperature, relative humidity, cloud cover), measured and computed clear sky iradiances are in reasonable agreement. The STAR model is applied to build up the solar UV geographic patterns in Italy: the daily dose in the range 290-325 nm is computed at about 70 sites where a thorough and homogeneous climatology is available. For each month the concept of an idealized "standard day" is introduced and the surface distribution of solar UV field determined. The map of solar UV patterns for Italy, available for the first time, meets the study requirements in the field of skin and eye epidemiology, as well as in other investigations dealing with the impact of UV on the biosphere. The results are interpreted in terms of atmospheric and meteorological parameters modulating UV radiation reaching the ground.

High-speed photorefractive keratectomy with femtosecond ultraviolet pulses

NASA Astrophysics Data System (ADS)

Danieliene, Egle; Gabryte, Egle; Vengris, Mikas; Ruksenas, Osvaldas; Gutauskas, Algimantas; Morkunas, Vaidotas; Danielius, Romualdas

2015-05-01

Femtosecond near-infrared lasers are widely used for a number of ophthalmic procedures, with flap cutting in the laser-assisted in situ keratomileusis (LASIK) surgery being the most frequent one. At the same time, lasers of this type, equipped with harmonic generators, have been shown to deliver enough ultraviolet (UV) power for the second stage of the LASIK procedure, the stromal ablation. However, the speed of the ablation reported so far was well below the currently accepted standards. Our purpose was to perform high-speed photorefractive keratectomy (PRK) with femtosecond UV pulses in rabbits and to evaluate its predictability, reproducibility and healing response. The laser source delivered femtosecond 206 nm pulses with a repetition rate of 50 kHz and an average power of 400 mW. Transepithelial PRK was performed using two different ablation protocols, to a total depth of 110 and 150 μm. The surface temperature was monitored during ablation; haze dynamics and histological samples were evaluated to assess outcomes of the PRK procedure. For comparison, analogous excimer ablation was performed. Increase of the ablation speed up to 1.6 s/diopter for a 6 mm optical zone using femtosecond UV pulses did not significantly impact the healing process.

Space Weathering Trends (UV and NIR) at Lunar Magnetic Anomalies

NASA Astrophysics Data System (ADS)

Blewett, D. T.; Denevi, B. W.; Cahill, J. T.; Klima, R. L.

2017-12-01

Areas of magnetized crustal rocks on the Moon, known as magnetic anomalies, affect the flux of solar-wind ions that bombard the lunar surface. Hence, magnetically shielded areas could experience a space weathering regime different from the lunar norm. The unusual, high-albedo markings called lunar swirls are collocated with magnetic anomalies. The high albedo in the near-ultraviolet through near-infrared is consistent with the presence of material that is less weathered than that found in mature, non-shielded areas. We have undertaken an analysis of spectral trends associated with swirls in order to gain further insight into the nature and origin of these features. We examine swirls in the near-ultraviolet (Lunar Reconnaissance Orbiter LROC-WAC) and near-infrared (Chandrayaan Moon Mineralogy Mapper and Kaguya Spectral Profiler). We find that relative to the normal weathering trend, the swirls have a steeper NIR continuum slope (i.e., the continuum is redder than expected for their albedo) and steeper UV slope (i.e., greater UV drop-off than expected for their albedo). These trends can be understood in terms of differing relative abundances of microphase and nanophase metallic iron weathering products.

GOME-2 Tropospheric Ozone Profile Retrievals from Joint UV/Visible Measurement

NASA Astrophysics Data System (ADS)

Liu, X.; Zoogman, P.; Chance, K.; Cai, Z.; Nowlan, C. R.; Huang, G.; Gonzalez Abad, G.

2016-12-01

It has been shown from sensitivity studies that adding visible measurements in the Chappuis ozone band to UV measurements in the Hartley/Huggins ozone bands can significantly enhance retrieval sensitivity to lower tropospheric ozone from backscattered solar radiances due to deeper photon penetration in the visible to the surface than in the ultraviolet. The first NASA EVI (Earth Venture Instrument) TEMPO (Tropospheric Emissions: Monitoring of Pollution) instrument is being developed to measure backscattered solar radiation in two channels ( 290-490 and 540-740 nm) and make atmospheric pollution measurements over North America from the Geostationary orbit. However, this retrieval enhancement has yet to be demonstrated from existing measurements due to the weak ozone absorption in the visible and strong interferences from surface reflectance and aerosols and the requirement of accurate radiometric calibration across different spectral channels. We present GOME-2 retrievals from joint UV/visible measurements using the SAO ozone profile retrieval algorithm, to directly explore the retrieval improvement in lower tropospheric ozone from additional visible measurements. To reduce the retrieval interference from surface reflectance, we add characterization of surface spectral reflectance in the visible based on combining EOFs (Empirical Orthogonal Functions) derived from ASTER and other surface reflectance spectra with MODIS BRDF climatology into the ozone profile algorithm. The impacts of various types of aerosols and surface BRDF on the retrievals will be investigated. In addition, we will also perform empirical radiometric calibration of the GOME-2 data based on radiative transfer simulations. We will evaluate the retrieval improvement of joint UV/visible retrieval over the UV retrieval based on fitting quality and validation against ozonesonde observations.

A Nonequilibrium Finite-Rate Carbon Ablation Model for Radiating Earth Re-entry Flows

DTIC Science & Technology

2015-09-17

model was a short half-cylinder made of isomolded graphite and was tested in 8.6 km/ s Earth entry ow. The model surface was heated within a temperature...capsule [98, 49, 112]. For the Star- dust return capsule that had an Earth entry velocity of 12 km/ s , equilibrium surface recession was over predicted...was tested at 8.6 km/ s Earth entry ow monitored by ultraviolet (UV) spec- trometry. The experiments pre-heated the model to high temperatures to

Antireflective coating for AgBr-TlI and AgBr-TlBr0.46I0.54 solid solution crystals

NASA Astrophysics Data System (ADS)

Korsakov, Alexandr; Salimgareev, Dmitrii; Lvov, Alexandr; Zhukova, Liya

2016-12-01

We researched the process of ultraviolet (UV) irradiation for the crystals of AgBr-TlI and AgBr-TlBr0.46I0.54 systems. It was found that on the surface of irradiated crystals, the film is formed and film grain size depends on exposure time and crystal composition. This film proved to gain the transmission by reducing the reflection from its surface within the 8.0-27.0 μm range.

Satellite Estimation of Spectral Surface UV Irradiance. 2; Effect of Horizontally Homogeneous Clouds

NASA Technical Reports Server (NTRS)

Krothov, N.; Herman, J. R.; Bhartia, P. K.; Ahmad, Z.a; Fioletov, V.

1998-01-01

The local variability of UV irradiance at the Earth's surface is mostly caused by clouds in addition to the seasonal variability. Parametric representations of radiative transfer RT calculations are presented for the convenient solution of the transmission T of ultraviolet radiation through plane parallel clouds over a surface with reflectivity R(sub s). The calculations are intended for use with the Total Ozone Mapping Spectrometer (TOMS) measured radiances to obtain the calculated Lambert equivalent scene reflectivity R for scenes with and without clouds. The purpose is to extend the theoretical analysis of the estimation of UV irradiance from satellite data for a cloudy atmosphere. Results are presented for a range of cloud optical depths and solar zenith angles for the cases of clouds over a low reflectivity surface R(sub s) less than 0.1, over a snow or ice surface R(sub s) greater than 0.3, and for transmission through a non-conservative scattering cloud with single scattering albedo omega(sub 0) = 0.999. The key finding for conservative scattering is that the cloud-transmission function C(sub T), the ratio of cloudy-to clear-sky transmission, is roughly C(sub T) = 1 - R(sub c) with an error of less than 20% for nearly overhead sun and snow-free surfaces. For TOMS estimates of UV irradiance in the presence of both snow and clouds, independent information about snow albedo is needed for conservative cloud scattering. For non-conservative scattering with R(sub s) greater than 0.5 (snow) the satellite measured scene reflectance cannot be used to estimate surface irradiance. The cloud transmission function has been applied to the calculation of UV irradiance at the Earth's surface and compared with ground-based measurements.

Formation of the UV Spectrum of Molecular Hydrogen in the Sun

NASA Astrophysics Data System (ADS)

Jaeggli, S. A.; Judge, P. G.; Daw, A. N.

2018-03-01

Ultraviolet (UV) lines of molecular hydrogen have been observed in solar spectra for almost four decades, but the behavior of the molecular spectrum and its implications for solar atmospheric structure are not fully understood. Data from the High-Resolution Telescope Spectrometer (HRTS) instrument revealed that H2 emission forms in particular regions, selectively excited by a bright UV transition region and chromospheric lines. We test the conditions under which H2 emission can originate by studying non-LTE models, sampling a broad range of temperature stratifications and radiation conditions. Stratification plays the dominant role in determining the population densities of H2, which forms in greatest abundance near the continuum photosphere. However, opacity due to the photoionization of Si and other neutrals determines the depth to which UV radiation can penetrate to excite the H2. Thus the majority of H2 emission forms in a narrow region, at about 650 km in standard one-dimensional (1D) models of the quiet Sun, near the τ = 1 opacity surface for the exciting UV radiation, generally coming from above. When irradiated from above using observed intensities of bright UV emission lines, detailed non-LTE calculations show that the spectrum of H2 seen in the quiet-Sun Solar Ultraviolet Measurement of Emitted Radiation atlas spectrum and HRTS light-bridge spectrum can be satisfactorily reproduced in 1D stratified atmospheres, without including three-dimensional or time-dependent thermal structures. A detailed comparison to observations from 1205 to 1550 Å is presented, and the success of this 1D approach to modeling solar UV H2 emission is illustrated by the identification of previously unidentified lines and upper levels in HRTS spectra.

IUS materials outgassing condensation effects on sensitive spacecraft surfaces

NASA Technical Reports Server (NTRS)

Mullen, C. R.; Shaw, C. G.; Crutcher, E. R.

1982-01-01

Four materials used on the inertial upper state (IUS) were subjected to vacuum conditions and heated to near-operational temperatures (93 to 316 C), releasing volatile materials. A fraction of the volatile materials were collected on 25 C solar cells, optical solar reflectors (OSR's) or aluminized Mylar. The contaminated surfaces were exposed to 26 equivalent sun hours of simulated solar ultraviolet (UV) radiation. Measurements of contamination deposit mass, structure, reflectance and effects on solar cell power output were made before and after UV irradiation. Standard total mass loss - volatile condensible materials (TML - VCM) tests were also performed. A 2500 A thick contaminant layer produced by EPDM rubber motor-case insulation outgassing increased the solar absorptance of the OSR's from 0.07 to 0.14, and to 0.18 after UV exposure. An 83,000 A layer caused an increase from 0.07 to 0.21, and then the 0.46 after UV exposure. The Kevlar-epoxy motor-case material outgassing condensation raised the absorptance from 0.07 to 0.13, but UV had no effect. Outgassing from multilayer insulation and carbon-carbon nozzle materials did not affect the solar absorptance of the OSR's.

Effects of protective resin coating on the surface roughness and color stability of resin-based restorative materials.

PubMed

Bagis, Bora; Tüzüner, Tamer; Turgut, Sedanur; Korkmaz, Fatih Mehmet; Baygın, Özgül; Bağış, Yıldırım Hakan

2014-01-01

The aim of this study was to evaluate the effects of nanofilled protective resin coating (RC) on the surface roughness (Ra) and color stability (ΔE) of resin-based restorative materials (RM) (compomer (C), nanofilled composite (NF), and microhybrid composite (MH)) after being submitted to the ultraviolet aging (UV) method. Thirty-six specimens were prepared (n = 6 for each group). The Ra and (ΔE) values and SEM images were obtained before and after UV. Significant interactions were found among the RM-RC-UV procedures for Ra (P < 0.001). After the specimens were submitted to UV, the Ra values were significantly increased, regardless of the RC procedure (with RC; P < 0.01 for all, without RC; C (P < 0.01), NF (P < 0.001), and MH (P < 0.001)) for each RM. Significant interactions were found between the RM-RC (P < 0.001) procedures for the ΔE values. The ΔE values were increased in each group after applying the RC procedures (P < 0.001). Protective RC usage for RM could result in material-related differences in Ra and ΔE as with used UV method.

Effects of Protective Resin Coating on the Surface Roughness and Color Stability of Resin-Based Restorative Materials

PubMed Central

Tüzüner, Tamer; Korkmaz, Fatih Mehmet; Baygın, Özgül; Bağış, Yıldırım Hakan

2014-01-01

The aim of this study was to evaluate the effects of nanofilled protective resin coating (RC) on the surface roughness (Ra) and color stability (ΔE) of resin-based restorative materials (RM) (compomer (C), nanofilled composite (NF), and microhybrid composite (MH)) after being submitted to the ultraviolet aging (UV) method. Thirty-six specimens were prepared (n = 6 for each group). The Ra and (ΔE) values and SEM images were obtained before and after UV. Significant interactions were found among the RM-RC-UV procedures for Ra (P < 0.001). After the specimens were submitted to UV, the Ra values were significantly increased, regardless of the RC procedure (with RC; P < 0.01 for all, without RC; C (P < 0.01), NF (P < 0.001), and MH (P < 0.001)) for each RM. Significant interactions were found between the RM-RC (P < 0.001) procedures for the ΔE values. The ΔE values were increased in each group after applying the RC procedures (P < 0.001). Protective RC usage for RM could result in material-related differences in Ra and ΔE as with used UV method. PMID:25162066

ADVANCED OXIDATION PROCESS TECHNOLOGY (ULTRAVIOLET RADIATION/OZONE TREATMENT) FOR REMOVAL OF METHYL TERTIARY BUTYL ETHER (MTBE) IN GROUND WATER SUPPLIES.

EPA Science Inventory

U.S. EPA’s Office of Research and Development in Cincinnati, Ohio has been testing and evaluating MTBE removal in dechlorinated tap water using three oxidant combinations: hydrogen peroxide/ozone, ultraviolet irradiation (UV)/ozone, and UV/ozone/hydrogen peroxide. Pilot-scale st...

Spatial and Temporal Variability of Solar Ultraviolet Exposure of Coral Assemblages in the Florida Keys: Importance of Colored Dissolved Organic Matter x

EPA Science Inventory

Solar ultraviolet (UV) radiation can have deleterious effects on coral assemblages in tropical and subtropical marine environments, but little information is available on UV penetration into ocean waters surrounding corals. Here we provide an extensive data set of optical propert...

DISTRIBUTION PATTERNS OF LENTIC-BREEDING AMPHIBIANS IN RELATION OF ULTRAVIOLET RADIATION EXPOSURE IN WESTERN NORTH AMERICA

EPA Science Inventory

An increase in ultraviolet (UV-B) radiation has been posited to be a potential factor in the decline of some amphibian population...Much more work is still needed to determine whether UV-B, either alone or in concert with other factors, is causing widespread population losses in ...

The ultraviolet radiation environment of pollen and its effect on pollen germination

NASA Technical Reports Server (NTRS)

1981-01-01

The damage to pollen caused by natural ultraviolet radiation was investigated. Experimental and literature research into the UV radiation environment is reported. Viability and germination of wind and insect pollinated species were determined. Physiological, developmental, and protective factors influencing UV sensitivity of binucleate, advanced binucleate, and trinucleate pollen grains are compared.

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

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

Choudhury, F. A.; Nguyen, H. M.; Shohet, J. L., E-mail: shohet@engr.wisc.edu

This work addresses the effect of ultraviolet radiation of wavelengths longer than 250 nm on Si-CH{sub 3} bonds in porous low-k dielectrics. Porous low-k films (k = 2.3) were exposed to 4.9 eV (254 nm) ultraviolet (UV) radiation in both air and vacuum for one hour. Using Fourier Transform Infrared (FTIR) spectroscopy, the chemical structures of the dielectric films were analyzed before and after the UV exposure. UV irradiation in air led to Si-CH{sub 3} bond depletion in the low-k material and made the films hydrophilic. However, no change in Si-CH{sub 3} bond concentration was observed when the same samplesmore » were exposed to UV under vacuum with a similar fluence. These results indicate that UV exposures in vacuum with wavelengths longer than ∼250 nm do not result in Si-CH{sub 3} depletion in low-k films. However, if the irradiation takes place in air, the UV irradiation removes Si-CH{sub 3} although direct photolysis of air species does not occur above ∼242 nm. We propose that photons along with molecular oxygen and, water, synergistically demethylate the low-k films.« less

Comparative experimental and simulation studies of high-power AlGaN-based 353 nm ultraviolet flip-chip and top-emitting LEDs

NASA Astrophysics Data System (ADS)

Liu, Mengling; Zhou, Shengjun; Liu, Xingtong; Gao, Yilin; Ding, Xinghuo

2018-03-01

Experimental and simulation studies of high-power AlGaN-based 353 nm ultraviolet (UV) flip-chip (FC) and top-emitting (TE) light-emitting diodes (LEDs) are performed here. To improve the optical and electrical properties of ultraviolet LEDs, we fabricate high-power FC-UV LEDs with Ta2O5/SiO2 distributed Bragg reflectors (DBRs) and a strip-shaped SiO2 current blocking layer (CBL). The reflectance of fourteen pairs of Ta2O5/SiO2 DBRs is 96.4% at 353 nm. The strip-shaped SiO2 CBL underneath the strip-shaped p-electrode can prevent the current concentrating in regions immediately adjacent to the p-electrode where the overlying opaque p-electrode metal layer absorbs the emitted UV light. Moreover, two-level metallization electrodes are used to improve current spreading. Our numerical results show that FC-UV LED has a more favorable current spreading uniformity than TE-UV LED. The light output power of 353 nm FC-UV LED was 23.22 mW at 350 mA, which is 24.7% higher than that of TE-UV LED.

Emulsifying and foaming properties of ultraviolet-irradiated egg white protein and sodium caseinate.

PubMed

Kuan, Yau-Hoong; Bhat, Rajeev; Karim, Alias A

2011-04-27

The physicochemical and functional properties of ultraviolet (UV)-treated egg white protein (EW) and sodium caseinate (SC) were investigated. UV irradiation of the proteins was carried out for 30, 60, 90, and 120 min. However, the SC samples were subjected to extended UV irradiation for 4 and 6 h as no difference was found on the initial UV exposure time. Formol titration, SDS-PAGE, and FTIR analyses indicated that UV irradiation could induce cross-linking on proteins and led to improved emulsifying and foaming properties (P < 0.05). These results indicated that the UV-irradiated EW and SC could be used as novel emulsifier and foaming agents in broad food systems for stabilizing and foaming purposes.

Spectral transmittance of UV-blocking soft contact lenses: a comparative study.

PubMed

Rahmani, Saeed; Mohammadi Nia, Mohadeseh; Akbarzadeh Baghban, Alireza; Nazari, Mohammad Reza; Ghassemi-Broumand, Mohammad

2014-12-01

Three major parts of sunlight consist of visible, ultraviolet and infrared radiation. Exposure to ultraviolet radiation (UVR) can result in a spectrum of skin and ocular diseases. UV-blocking contact lenses help provide protection against harmful UV radiation. We studied the ultraviolet and visible light rays transmission in some soft UV-blocking contact lenses. Four available tinted soft lenses (Acuvue Moist, Zeiss CONTACT Day 30 Air spheric, Pretty Eyes and Sauflon 56 UV) have been evaluated for UV and visible transmission. One-way ANOVA testing was performed to establish is there a statistically significant difference between the UV regions and visible spectra means for the contact lenses (α=0.05). Pretty Eyes, Zeiss CONTACT, Acuvue Moist and Sauflon 56 UV showed UV-B transmittance value of 0.65%, 10.69%, 1.22%, and 5.78%, respectively. Pretty Eyes and Acuvue Moist had UV-A transmittance values of 32% and 34%, Sauflon 56 UV and Zeiss CONTACT had transmittance values of 48% and 43%, respectively. All of the studied lenses transmitted at least 94.6% on the visible spectrum. The results of the one-way ANOVA statistical analysis show that a statistically significant difference exists within the group of contact lenses tested for the visible (p<0.001), UV-B (p<0.001) and UV-A (p<0.001) portions of the spectrum (α=0.05). Acuvue Moist has the best UV-blocking property and also visible transmission between other tested contact lenses in this study. Copyright © 2014 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

The GALEX Time Domain Survey. I. Selection and Classification of Over a Thousand Ultraviolet Variable Sources

NASA Astrophysics Data System (ADS)

Gezari, S.; Martin, D. C.; Forster, K.; Neill, J. D.; Huber, M.; Heckman, T.; Bianchi, L.; Morrissey, P.; Neff, S. G.; Seibert, M.; Schiminovich, D.; Wyder, T. K.; Burgett, W. S.; Chambers, K. C.; Kaiser, N.; Magnier, E. A.; Price, P. A.; Tonry, J. L.

2013-03-01

We present the selection and classification of over a thousand ultraviolet (UV) variable sources discovered in ~40 deg2 of GALEX Time Domain Survey (TDS) NUV images observed with a cadence of 2 days and a baseline of observations of ~3 years. The GALEX TDS fields were designed to be in spatial and temporal coordination with the Pan-STARRS1 Medium Deep Survey, which provides deep optical imaging and simultaneous optical transient detections via image differencing. We characterize the GALEX photometric errors empirically as a function of mean magnitude, and select sources that vary at the 5σ level in at least one epoch. We measure the statistical properties of the UV variability, including the structure function on timescales of days and years. We report classifications for the GALEX TDS sample using a combination of optical host colors and morphology, UV light curve characteristics, and matches to archival X-ray, and spectroscopy catalogs. We classify 62% of the sources as active galaxies (358 quasars and 305 active galactic nuclei), and 10% as variable stars (including 37 RR Lyrae, 53 M dwarf flare stars, and 2 cataclysmic variables). We detect a large-amplitude tail in the UV variability distribution for M-dwarf flare stars and RR Lyrae, reaching up to |Δm| = 4.6 mag and 2.9 mag, respectively. The mean amplitude of the structure function for quasars on year timescales is five times larger than observed at optical wavelengths. The remaining unclassified sources include UV-bright extragalactic transients, two of which have been spectroscopically confirmed to be a young core-collapse supernova and a flare from the tidal disruption of a star by dormant supermassive black hole. We calculate a surface density for variable sources in the UV with NUV < 23 mag and |Δm| > 0.2 mag of ~8.0, 7.7, and 1.8 deg-2 for quasars, active galactic nuclei, and RR Lyrae stars, respectively. We also calculate a surface density rate in the UV for transient sources, using the effective survey time at the cadence appropriate to each class, of ~15 and 52 deg-2 yr-1 for M dwarfs and extragalactic transients, respectively.

Strong composition dependence of adhesive properties of ultraviolet curing adhesives with modified acrylates

NASA Astrophysics Data System (ADS)

Feng, Yefeng; Li, Yandong; Wang, Fupeng; Peng, Cheng; Xu, Zhichao; Hu, Jianbing

2018-05-01

Ultraviolet (UV) curable adhesives have been widely researched in fields of health care and electronic components. UV curing systems with modified acrylic ester prepolymers have been frequently employed. In order to clarify composition dependence of adhesive properties of adhesives containing modified acrylates, in this work, several UV curing adhesives bearing urethane and epoxy acrylates were designed and fabricated. The effects of prepolymer, diluent, feed ratio, initiator and assistant on adhesive performances were investigated. This work might offer a facile route to gain promising high-performance UV curable adhesives with desired adhesive traits through regulating their compositions.

The influence of oxidation reduction potential and water treatment processes on quartz lamp sleeve fouling in ultraviolet disinfection reactors.

PubMed

Wait, Isaac W; Johnston, Cliff T; Blatchley, Ernest R

2007-06-01

Ultraviolet (UV) disinfection systems are incorporated into drinking water production facilities because of their broad-spectrum antimicrobial capabilities, and the minimal disinfection by-product formation that generally accompanies their use. Selection of an optimal location for a UV system within a drinking water treatment facility depends on many factors; a potentially important consideration is the effect of system location on operation and maintenance issues, including the potential for fouling of quartz surfaces. To examine the effect of system location on fouling, experiments were conducted at a groundwater treatment facility, wherein aeration, chlorination, and sand filtration were applied sequentially for treatment. In this facility, access to the water stream was available prior to and following each of the treatment steps. Therefore, it was possible to examine the effects of each of these unit operations on fouling dynamics within a UV system. Results indicated zero-order formation kinetics for the fouling reactions at all locations. Increases in oxidation reduction potential, caused by water treatment steps such as aeration and chlorination, increased the rate of sleeve fouling and the rate of irradiance loss within the reactor. Analysis of metals in the sleeve foulant showed that calcium and iron predominate, and relative comparisons of foulant composition to water chemistry highlighted a high affinity for incorporation into the foulant matrix for both iron and manganese, particularly after oxidizing treatment steps. Fouling behavior was observed to be in qualitative agreement with representations of the degree of saturation, relative to the metal:ligand combinations that are believed to comprise a large fraction of the foulants that accumulate on the surfaces of quartz jackets in UV systems used to treat water.

Detection of ultraviolet radiation using tissue equivalent radiochromic gel materials

NASA Astrophysics Data System (ADS)

Bero, M. A.; Abukassem, I.

2009-05-01

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

SLR digital camera for forensic photography

NASA Astrophysics Data System (ADS)

Har, Donghwan; Son, Youngho; Lee, Sungwon

2004-06-01

Forensic photography, which was systematically established in the late 19th century by Alphonse Bertillon of France, has developed a lot for about 100 years. The development will be more accelerated with the development of high technologies, in particular the digital technology. This paper reviews three studies to answer the question: Can the SLR digital camera replace the traditional silver halide type ultraviolet photography and infrared photography? 1. Comparison of relative ultraviolet and infrared sensitivity of SLR digital camera to silver halide photography. 2. How much ultraviolet or infrared sensitivity is improved when removing the UV/IR cutoff filter built in the SLR digital camera? 3. Comparison of relative sensitivity of CCD and CMOS for ultraviolet and infrared. The test result showed that the SLR digital camera has a very low sensitivity for ultraviolet and infrared. The cause was found to be the UV/IR cutoff filter mounted in front of the image sensor. Removing the UV/IR cutoff filter significantly improved the sensitivity for ultraviolet and infrared. Particularly for infrared, the sensitivity of the SLR digital camera was better than that of the silver halide film. This shows the possibility of replacing the silver halide type ultraviolet photography and infrared photography with the SLR digital camera. Thus, the SLR digital camera seems to be useful for forensic photography, which deals with a lot of ultraviolet and infrared photographs.

A two-dimensional atmospheric chemistry modeling investigation of Earth's Phanerozoic O3 and near-surface ultraviolet radiation history

NASA Astrophysics Data System (ADS)

Harfoot, Michael B. J.; Beerling, David J.; Lomax, Barry H.; Pyle, John A.

2007-04-01

We use the Cambridge two-dimensional (2-D) chemistry-radiation transport model to investigate the implications for column O3 and near-surface ultraviolet radiation (UV), of variations in atmospheric O2 content over the Phanerozoic (last 540 Myr). Model results confirm some earlier 1-D model investigations showing that global annual mean O3 column increases monotonically with atmospheric O2. Sensitivity studies indicate that changes in temperature and N2O exert a minor influence on O3 relative to O2. We reconstructed Earth's O3 history by interpolating the modeled relationship between O3 and O2 onto two Phanerozoic O2 histories. Our results indicate that the largest variation in Phanerozoic column O3 occurred between 400 and 200 Myr ago, corresponding to a rise in atmospheric O2 to ˜1.5 times the present atmospheric level (PAL) and subsequent fall to ˜0.5 PAL. The O3 response to this O2 decline shows latitudinal differences, thinning most at high latitudes (30-40 Dobson units (1 DU = 0.001 atm cm) at 66°N) and least at low latitudes (5-10 DU at 9°N) where a "self-healing" effect is evident. This O3 depletion coincides with significant increases in the near-surface biologically active UV radiation at high latitudes, +28% as weighted by the Thimijan spectral weighting function. O3 and UV changes were exacerbated when we incorporated a direct feedback of the terrestrial biosphere on atmospheric chemistry, through enhanced N2O production as the climate switched from an icehouse to a greenhouse mode. On the basis of a summary of field and laboratory experimental evidence, we suggest that these UV radiation increases may have exerted subtle rather than catastrophic effects on ecosystem processes.

UV-driven microvalve based on a micro-nano TiO₂/SiO₂ composite surface for microscale flow control.

PubMed

Guo, Ting; Meng, Tao; Li, Wei; Qin, Jilong; Tong, Zhiping; Zhang, Qing; Li, Xueru

2014-03-28

This paper presents a novel ultraviolet (UV)-driven microvalve based on the concept of inserting a trimethyl chlorosilane (CTMS) modified TiO₂/SiO₂ composite patch of switchable wettability in a microfluidic system. A unique micro-nano hierarchical structure was designed and used to enhance the overall wetting contrast with the aim of improving the wetting-based valve performances. Field-emission scanning electron microscopy (FE-SEM) and x-ray photoelectron spectroscopy (XPS) were used to characterize the morphology and chemical composition of the surface. UV-driven wettability conversion on the patched microchannel was investigated using water column relative height tests, and the results confirmed the significant improvement of the hierarchical structure with the surface hydrophobic/hydrophilic conversion, which produced enhancements of 276% and 95% of the water-repellent and water-sucking pressures, respectively, compared with those of the single-scale TiO₂ nanopatterned structure. Accordingly, a good reversible and repeated on-off performance was identified by the valve tests, highlighting the potential application of the novel microvalve in the efficient control of microscale flow.

UV-driven microvalve based on a micro-nano TiO2/SiO2 composite surface for microscale flow control

NASA Astrophysics Data System (ADS)

Guo, Ting; Meng, Tao; Li, Wei; Qin, Jilong; Tong, Zhiping; Zhang, Qing; Li, Xueru

2014-03-01

This paper presents a novel ultraviolet (UV)-driven microvalve based on the concept of inserting a trimethyl chlorosilane (CTMS) modified TiO2/SiO2 composite patch of switchable wettability in a microfluidic system. A unique micro-nano hierarchical structure was designed and used to enhance the overall wetting contrast with the aim of improving the wetting-based valve performances. Field-emission scanning electron microscopy (FE-SEM) and x-ray photoelectron spectroscopy (XPS) were used to characterize the morphology and chemical composition of the surface. UV-driven wettability conversion on the patched microchannel was investigated using water column relative height tests, and the results confirmed the significant improvement of the hierarchical structure with the surface hydrophobic/hydrophilic conversion, which produced enhancements of 276% and 95% of the water-repellent and water-sucking pressures, respectively, compared with those of the single-scale TiO2 nanopatterned structure. Accordingly, a good reversible and repeated on-off performance was identified by the valve tests, highlighting the potential application of the novel microvalve in the efficient control of microscale flow.

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

PubMed

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

2015-01-01

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

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

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

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

1980-09-01

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

How does solar ultraviolet-B radiation improve drought tolerance of silver birch (Betula pendula Roth.) seedlings?

PubMed

Robson, T Matthew; Hartikainen, Saara M; Aphalo, Pedro J

2015-05-01

We hypothesized that solar ultraviolet (UV) radiation would protect silver birch seedlings from the detrimental effects of water stress through a coordinated suite of trait responses, including morphological acclimation, improved control of water loss through gas exchange and hydraulic sufficiency. To better understand how this synergetic interaction works, plants were grown in an experiment under nine treatment combinations attenuating ultraviolet-A and ultraviolet-B (UVB) from solar radiation together with differential watering to create water-deficit conditions. In seedlings under water deficit, UV attenuation reduced height growth, leaf production and leaf length compared with seedlings receiving the full spectrum of solar radiation, whereas the growth and morphology of well-watered seedlings was largely unaffected by UV attenuation. There was an interactive effect of the treatment combination on water relations, which was more apparent as a change in the water potential at which leaves wilted or plants died than through differences in gas exchange. This suggests that changes occur in the cell wall elastic modulus or accumulation of osmolites in cells under UVB. Overall, the strong negative effects of water deficit are partially ameliorated by solar UV radiation, whereas well-watered silver birch seedlings are slightly disadvantaged by the solar UV radiation they receive. © 2014 John Wiley & Sons Ltd.

Improvement in ultraviolet based decontamination rate using meta-materials

NASA Astrophysics Data System (ADS)

Enaki, Nicolae A.; Bazgan, Sergiu; Ciobanu, Nellu; Turcan, Marina; Paslari, Tatiana; Ristoscu, Carmen; Vaseashta, Ashok; Mihailescu, Ion N.

2017-09-01

We propose a method of decontamination using photon-crystals consisting of microspheres and fiber optics structures with various geometries. The efficient decontamination using the surface of the evanescent zone of meta-materials opens a new perspective in the decontamination procedures. We propose different topological structures of meta-materials to increase the contact surface of UV radiation with contaminated liquid. Recent observation of the trapping of dielectric particles along the fibers help us propose a new perspective on the new possibilities to trap the viruses, bacteria and other microorganisms from liquids, in this special zone, where the effective UV coherent Raman decontamination becomes possible. The nonlinear theory of the excitation of vibration modes of bio-molecule of viruses and bacteria is revised, taking into consideration the bimodal coherent states in coherent Raman excitation of biomolecules.

Reducing cross-sensitivity of TiO2-(B) nanowires to humidity using ultraviolet illumination for trace explosive detection.

PubMed

Wang, Danling; Chen, Antao; Jen, Alex K-Y

2013-04-14

Environmental humidity is an important factor that can influence the sensing performance of a metal oxide. TiO2-(B) in the form of nanowires has been demonstrated to be a promising material for the detection of explosive gases such as 2,4,6-trinitrotoluene (TNT). However, the elimination of cross-sensitivity of the explosive detectors based on TiO2-(B) toward environmental humidity is still a major challenge. It was found that the cross-sensitivity could be effectively modulated when the thin film of TiO2-(B) nanowires was exposed to ultraviolet (UV) light during the detection of explosives under operating conditions. Such a modulation of sensing responses of TiO2-(B) nanowires to explosives by UV light was attributed to a photocatalytic effect, with which the water adsorbed on the TiO2-(B) nanowire surface was split and therefore the sensor response performance was less affected. It was revealed that the cross-sensitivity could be suppressed up to 51% when exposed to UV light of 365 nm wavelength with an intensity of 40 mW cm(-2). This finding proves that the reduction of cross-sensitivity to humidity through UV irradiation is an effective approach that can improve the performance of a sensor based on TiO2-(B) nanowires for the detection of explosive gas.

Ultraviolet Radiation Dose National Standard of México

NASA Astrophysics Data System (ADS)

Cardoso, R.; Rosas, E.

2006-09-01

We present the Ultraviolet (UV) Radiation Dose National Standard for México. The establishment of this measurement reference at Centro Nacional de Metrología (CENAM) eliminates the need of contacting foreign suppliers in the search for traceability towards the SI units when calibrating instruments at 365 nm. Further more, the UV Radiation Dose National Standard constitutes a highly accurate and reliable source for the UV radiation dose measurements performed in medical and cosmetic treatments as in the the food and pharmaceutics disinfection processes, among other.

The influence of UV radiation on protistan evolution

NASA Technical Reports Server (NTRS)

Rothschild, L. J.

1999-01-01

Ultraviolet radiation has provided an evolutionary challenge to life on Earth. Recent increases in surficial ultraviolet B fluxes have focused attention on the role of UV radiation in protistan ecology, cancer, and DNA damage. Exploiting this new wealth of data, I examine the possibility that ultraviolet radiation may have played a significant role in the evolution of the first eukaryotes, that is, protists. Protists probably arose well before the formation of a significant ozone shield, and thus were probably subjected to substantial ultraviolet A, ultraviolet B, and ultraviolet C fluxes early in their evolution. Evolution consists of the generation of heritable variations and the subsequent selection of these variants. Ultraviolet radiation has played a role both as a mutagen and as a selective agent. In its role as a mutagen, it may have been crucial in the origin of sex and as a driver of molecular evolution. As a selective agent, its influence has been broad. Discussed in this paper are the influence of ultraviolet radiation on biogeography, photosynthesis, and desiccation resistance.

NASA's Potential Contributions for Using Solar Ultraviolet Radiation in Conjunction with Photocatalysis for Urban Air Pollution Mitigation

NASA Technical Reports Server (NTRS)

Ryan, robert E.; Underwood, Lauren W.

2007-01-01

More than 75 percent of the U.S. population lives in urban communities where people are exposed to levels of smog or pollution that exceed the EPA (U.S. Environmental Protection Agency) safety standards. Urban air quality presents a unique problem because of a number of complex variables, including traffic congestion, energy production, and energy consumption activities, all of which can contribute to and affect air pollution and air quality in this environment. In environmental engineering, photocatalysis is an area of research whose potential for environmental clean-up is rapidly developing popularity and success. Photocatalysis, a natural chemical process, is the acceleration of a photoreaction in the presence of a catalyst. Photocatalytic agents are activated when exposed to near UV (ultraviolet) light (320-400 nm) and water. In recent years, surfaces coated with photocatalytic materials have been extensively studied because pollutants on these surfaces will degrade when the surfaces are exposed to near UV light. Building materials, such as tiles, cement, glass, and aluminum sidings, can be coated with a thin film of a photocatalyst. These coated materials can then break down organic molecules, like air pollutants and smog precursors, into environmentally friendly compounds. These surfaces also exhibit a high affinity for water when exposed to UV light. Therefore, not only are the pollutants decomposed, but this superhydrophilic nature makes the surface self-cleaning, which helps to further increase the degradation rate by allowing rain and/or water to wash byproducts away. According to the Clean Air Act, each individual state is responsible for implementing prevention and regulatory programs to control air pollution. To operate an air quality program, states must adopt and/or develop a plan and obtain approval from the EPA. Federal approval provides a means for the EPA to maintain consistency among different state programs and ensures that they comply with the requirements of the Clean Air Act.

Estimation of UV index in the clear-sky using OMI PROFOZ and AERONET data

NASA Astrophysics Data System (ADS)

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

2016-12-01

Due to a strong influence to the human health and ecosystem environment, continuous monitoring of the surface-level ultraviolet (UV) radiation is important nowadays. UV index (UVI) is a simple parameter to show the strength of surface UV radiation, therefore UVI has been widely utilized for the purpose of UV monitoring. In this work, we also try to develop our own retrieval algorithm for better estimation of UVI. The amount of UVA (320-400 nm) and UVB (290-320 nm) radiation at the Earth surface depends on the extent of Rayleigh scattering by atmospheric gas molecules, the radiative absorption by ozone, radiative scattering by clouds, and both absorption and scattering by airborne aerosols. Thus advanced consideration of these factors is the essential part to establish the process of UVI estimation. In this study, we estimate UV Index (UVI) at Seoul first in a clear-sky atmosphere, and then validate this estimated UVI comparing to UVI from Brewer spectrophotometer measurements located at Yonsei University in Seoul. We use the Vector Linearized Discrete Ordinate Radiative Transfer (VLIDORT) model version 2.6 for our UVI calculation. To consider the ozone and aerosol influence in a real situation, we input ozone and temperature profiles from the Ozone Monitoring Instrument (OMI) Aura vertical profile ozone (PROFOZ) data, and aerosol properties from the AErosol RObotic NETwork (AERONET) measurements at Seoul into the model. Inter-comparison of UVI is performed for the year 2011, 2012 and 2014, and resulted in a high correlation coefficient (R=0.95) under clear-sky condition. But a slight overestimation of Brewer UVI occurred under high AOD conditions in clear-sky. Because our UVI algorithm does not account for surface absorbing aerosols, it is lead to systematic overestimation of surface UV irradiances. Therefore, we also investigate the effect of absorbing aerosol on the amount of UV irradiance in the clear-sky over East Asia.

Surface modification of Polycaprolactone (PCL) microcarrier for performance improvement of human skin fibroblast cell culture

NASA Astrophysics Data System (ADS)

Samsudin, N.; Hashim, Y. Z. H.; Arifin, M. A.; Mel, M.; Salleh, H. Mohd; Sopyan, I.; Hamid, M. Abdul

2018-01-01

Polycaprolactone (PCL) has many advantages for use in biomedical engineering field. In the present work PCL microcarriers of 150-200 μm were fabricated using oil-in-water (o/w) emulsification coupled with solvent evaporation method. The surface charge of PCL microcarrier was then been improved by using ultraviolet/ozone treatment to introduce oxygen functional group. Immobilisation of gelatin onto PCL microspheres using zero-length crosslinker provides a stable protein-support complex, with no diffusional barrier which is ideal for mass processing. The optimum concentration of carboxyl group (COOH) absorbed on the surface was 1495.9 nmol/g and the amount of gelatin immobilized was 1797.3 μg/g on UV/O3 treated microcarriers as compared to the untreated (320 μg/g) microcarriers. The absorption of functional oxygen groups on the surface and the immobilized gelatin was confirmed with Fourier Transformed Infrared spectroscopy and the enhancement of hydrophilicity of the surface was confirmed using water contact angle measurement which decreased (86.93° - 49.34°) after UV/O3 treatment and subsequently after immobilisation of gelatin. The attachment and growth kinetics for human skin fibroblast cell (HSFC) showed that adhesion occurred much more rapidly for gelatin immobilised surface as compared to untreated PCL and UV/O3 PCL microcarrier.

A Real-Time Ultraviolet Radiation Imaging System Using an Organic Photoconductive Image Sensor†

PubMed Central

Okino, Toru; Yamahira, Seiji; Yamada, Shota; Hirose, Yutaka; Odagawa, Akihiro; Kato, Yoshihisa; Tanaka, Tsuyoshi

2018-01-01

We have developed a real time ultraviolet (UV) imaging system that can visualize both invisible UV light and a visible (VIS) background scene in an outdoor environment. As a UV/VIS image sensor, an organic photoconductive film (OPF) imager is employed. The OPF has an intrinsically higher sensitivity in the UV wavelength region than those of conventional consumer Complementary Metal Oxide Semiconductor (CMOS) image sensors (CIS) or Charge Coupled Devices (CCD). As particular examples, imaging of hydrogen flame and of corona discharge is demonstrated. UV images overlapped on background scenes are simply made by on-board background subtraction. The system is capable of imaging weaker UV signals by four orders of magnitude than that of VIS background. It is applicable not only to future hydrogen supply stations but also to other UV/VIS monitor systems requiring UV sensitivity under strong visible radiation environment such as power supply substations. PMID:29361742

Ultraviolet radiation as an ant repellent

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

Thorvilson, H.G.; Russell, S.A.; Green, B.

1996-12-31

In an effort to repel red imported fire ants (RIFA) from electrical devices, such as transformers, ultraviolet (UV) light was tested. Initial tests determined if RIFA`s tolerate a UV-irradiated environment when given a choice between UV-irradiated and non-irradiated. All replications in this test indicated that RIFA`s are intolerant of UV-irradiation and sought to escape it. RIFA`s moved to shaded environments and transported their brood out its well. A second test sought to determine if long-term UV-irradiation of the entire colonies cause increased RIFA mortality. Queenright colonies were exposed to UV irradiation of 254nm constantly for 115 days and colonies hadmore » a higher mortality rate than did a control colony. RIFA`s attempted to escape UV light and had increased rate when exposed to UV (254nm), but a practical application of this technique may be detrimental to insulation on electrical wiring.« less

Feasibility of Ultraviolet Light Emitting Diodes as an Alternative Light Source for Photocatalysis

NASA Technical Reports Server (NTRS)

Levine, Langanf H.; Richards, Jeffrey T.; Soler, Robert; Maxik, Fred; Coutts, Janelle; Wheeler, Raymond M.

2011-01-01

The objective of this study was to determine whether ultraviolet light emitting diodes (UV-LEDs) could serve as an alternative photon source efficiently for heterogeneous photocatalytic oxidation (PCO). An LED module consisting of 12 high-power UV-A LEDs was designed to be interchangeable with a UV-A fluorescent black light blue (BLB) lamp in a Silica-Titania Composite (STC) packed bed annular reactor. Lighting and thermal properties were characterized to assess the uniformity and total irradiant output. A forward current of (I(sub F)) 100 mA delivered an average irradiance of 4.0 m W cm(exp -2), which is equivalent to the maximum output of the BLB, but the irradiance of the LED module was less uniform than that of the BLB. The LED- and BLB-reactors were tested for the oxidization of 50 ppmv ethanol in a continuous flow-through mode with 0.94 sec space time. At the same irradiance, the UV-A LED reactor resulted in a lower PCO rate constant than the UV-A BLB reactor (19.8 vs. 28.6 nM CO2 sec-I), and consequently lower ethanol removal (80% vs. 91%) and mineralization efficiency (28% vs. 44%). Ethanol mineralization increased in direct proportion to the irradiance at the catalyst surface. This result suggests that reduced ethanol mineralization in the LED- reactor could be traced to uneven irradiance over the photocatalyst, leaving a portion of the catalyst was under-irradiated. The potential of UV-A LEDs may be fully realized by optimizing the light distribution over the catalyst and utilizing their instantaneous "on" and "off' feature for periodic irradiation. Nevertheless, the current UV-A LED module had the same wall plug efficiency (WPE) of 13% as that of the UV-A BLB. These results demonstrated that UV-A LEDs are a viable photon source both in terms of WPE and PCO efficiency.

Engineer's drawing of Skylab 4 Far Ultraviolet Electronographic camera

NASA Image and Video Library

1973-11-19

S73-36910 (November 1973) --- An engineer's drawing of the Skylab 4 Far Ultraviolet Electronographic camera (Experiment S201). Arrows point to various features and components of the camera. As the Comet Kohoutek streams through space at speeds of 100,000 miles per hour, the Skylab 4 crewmen will use the S201 UV camera to photograph features of the comet not visible from the Earth's surface. While the comet is some distance from the sun, the camera will be pointed through the scientific airlock in the wall of the Skylab space station Orbital Workshop (OWS). By using a movable mirror system built for the Ultraviolet Stellar Astronomy (S019) Experiment and rotating the space station, the S201 camera will be able to photograph the comet around the side of the space station. Photo credit: NASA

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

USDA-ARS?s Scientific Manuscript database

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

EFFECTS OF ULTRAVIOLET-B IRRADIANCE IN SOYBEAN. 6. INFLUENCE OF PHOSPHORUS NUTRITION ON GROWTH AND FLAVONIID CONTENT

EPA Science Inventory

Soybeans Glycine max Essex were hydroponically grown in a greenhouse at 2 levels of ultraviolet-B(UV-B) radiation and 4 levels of P. Plants were grown in each treatment combination to the complete expansion of the 4th trifoliolate leaf. UV-B radiation and reduced P supply general...

Mission Specialist Hawley works with the SWUIS experiment

NASA Image and Video Library

2013-11-18

STS093-350-022 (22-27 July 1999) --- Astronaut Steven A. Hawley, mission specialist, works with the Southwest Ultraviolet Imaging System (SWUIS) experiment onboard the Earth-orbiting Space Shuttle Columbia. The SWUIS is based around a Maksutov-design Ultraviolet (UV) telescope and a UV-sensitive, image-intensified Charge-Coupled Device (CCD) camera that frames at video frame rates.

Method and apparatus for passive optical dosimeter comprising caged dye molecules

DOEpatents

Sandison, David R.

2001-07-03

A new class of ultraviolet dosimeters is made possible by exposing caged dye molecules, which generate a dye molecule on exposure to ultraviolet radiation, to an exterior environment. Applications include sunburn monitors, characterizing the UV exposure history of UV-sensitive materials, especially including structural plastics, and use in disposable `one-use` optical equipment, especially medical devices.

Impact of enhanced ultraviolet-B irradiance on cotton growth, development, yield, and qualities under field conditions

Treesearch

Wei Gao; Youfei Zheng; James R. Slusser; Gordon M. Heisler

2003-01-01

The stratospheric ozone depletion and enhanced solar ultraviolet-B (UV-B) irradiance may have adverse impacts on the productivity of agricultural crops. The effect of UV-B enhancements on agricultural crops includes reduction in yield, alteration in species competition, decrease in photosynthetic activity, susceptibility to disease, and changes in structure and...

A study of meteor spectroscopy and physics from earth-orbit: A preliminary survey into ultraviolet meteor spectra

NASA Technical Reports Server (NTRS)

Meisel, D. D.

1976-01-01

Preliminary data required to extrapolate available meteor physics information (obtained in the photographic, visual and near ultraviolet spectral regions) into the middle and far ultraviolet are presented. Wavelength tables, telluric attenuation factors, meteor rates, and telluric airglow data are summarized in the context of near-earth observation vehicle parameters using moderate to low spectral resolution instrumentation. Considerable attenuation is given to the problem of meteor excitation temperatures since these are required to predict the strength of UV features. Relative line intensities are computed for an assumed chondritic composition. Features of greatest predicted intensities, the major problems in meteor physics, detectability of UV meteor events, complications of spacecraft motion, and UV instrumentation options are summarized.

Evaluating the impact of LED bulb development on the economic viability of ultraviolet technology for disinfection.

PubMed

Ibrahim, Mohamed A S; MacAdam, Jitka; Autin, Olivier; Jefferson, Bruce

2014-01-01

Ultraviolet (UV) technologies have been very successful in disinfection applications due to their ability to inactivate microorganisms without producing harmful disinfection by-products. However, there have been a number of concerns associated with the use of conventional UV systems such as hazardous mercury content, high capital investment and reduced electrical efficiency. These concerns have set limitations for the use of UV processes. The study evaluates the development of light emitting diode (LED) technology as an alternative UV source over the last 5 years, analyses the projections provided by the researchers and UV LED manufacturers and presents the information in a cost model with the aim to predict the timeline at which UV LED will compete with traditional UV low pressure high output technology in the commercial market at full-scale residential and industrial disinfection applications.

Calibration of the Voyager Ultraviolet Spectrometers and the Composition of the Heliosphere Neutrals: Reassessment

NASA Astrophysics Data System (ADS)

Ben-Jaffel, Lotfi; Holberg, J. B.

2016-06-01

The data harvest from the Voyagers’ (V 1 and V 2) Ultraviolet Spectrometers (UVS) covers encounters with the outer planets, measurements of the heliosphere sky-background, and stellar spectrophotometry. Because their period of operation overlaps with many ultraviolet missions, the calibration of V1 and V2 UVS with other spectrometers is invaluable. Here we revisit the UVS calibration to assess the intriguing sensitivity enhancements of 243% (V1) and 156% (V2) proposed recently. Using the Lyα airglow from Saturn, observed in situ by both Voyagers, and remotely by International Ultraviolet Explorer (IUE), we match the Voyager values to IUE, taking into account the shape of the Saturn Lyα line observed with the Goddard High Resolution Spectrograph on board the Hubble Space Telescope. For all known ranges of the interplanetary hydrogen density, we show that the V1 and V2 UVS sensitivities cannot be enhanced by the amounts thus far proposed. The same diagnostic holds for distinct channels covering the diffuse He I 58.4 nm emission. Our prescription is to keep the original calibration of the Voyager UVS with a maximum uncertainty of 30%, making both instruments some of the most stable EUV/FUV spectrographs in the history of space exploration. In that frame, we reassess the excess Lyα emission detected by Voyager UVS deep in the heliosphere, to show its consistency with a heliospheric but not galactic origin. Our finding confirms results obtained nearly two decades ago—namely, the UVS discovery of the distortion of the heliosphere and the corresponding obliquity of the local interstellar magnetic field (˜ 40^\\circ from upwind) in the solar system neighborhood—without requiring any revision of the Voyager UVS calibration.

UV-Resistant and Thermally Stable Superhydrophobic CeO2 Nanotubes with High Water Adhesion.

PubMed

Li, Xue-Ping; Sun, Ya-Li; Xu, Yao-Yi; Chao, Zi-Sheng

2018-06-03

A novel type of sticky superhydrophobic cerium dioxide (CeO 2 ) nanotube material is prepared by hydrothermal treatment without any chemical modification. A water droplet on the material surface shows a static water contact angle of about 157° but the water droplet is pinned on the material surface even when the material surface is turned upside down. Interestingly, the as-prepared CeO 2 nanotube material displays durable superhydrophobicity and enhanced adhesion to water under ultraviolet (UV) light irradiation. Importantly, this change in water adhesion can be reversed by heat treatment to restore the original adhesive value of 20 µL. Further, the maximum volume of the water droplet adhered on the material surface of CeO 2 nanotubes can be regulated without loss of superhydrophobicity during the heating treatment/UV-irradiation cycling. Meanwhile, the superhydrophobic CeO 2 nanotube material shows remarkable thermal stability even at temperatures as high as 450 °C, long-term durability in chemical environment, and air-storage and good resistance to oily contaminant. Finally, the potential application in no-loss water transportation of this sticky superhydrophobic CeO 2 material is demonstrated. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Influence of growth conditions and surface reaction byproducts on GaN grown via metal organic molecular beam epitaxy: Toward an understanding of surface reaction chemistry

NASA Astrophysics Data System (ADS)

Pritchett, David; Henderson, Walter; Burnham, Shawn D.; Doolittle, W. Alan

2006-04-01

The surface reaction byproducts during the growth of GaN films via metal organic molecular beam epitaxy (MOMBE) were investigated as a means to optimize material properties. Ethylene and ethane were identified as the dominant surface reaction hydrocarbon byproducts, averaging 27.63% and 7.15% of the total gas content present during growth. Intense ultraviolet (UV) photoexcitation during growth was found to significantly increase the abundance of ethylene and ethane while reducing the presence of H2 and N2. At 920°C, UV excitation was shown to enhance growth rate and crystalline quality while reducing carbon incorporation. Over a limited growth condition range, a 4.5×1019-3.4×1020 cm-3 variation in carbon incorporation was achieved at constant high vacuum. Coupled with growth rate gains, UV excitation yielded films with ˜58% less integrated carbon content. Structural material property variations are reported for various ammonia flows and growth temperatures. The results suggest that high carbon incorporation can be achieved and regulated during MOMBE growth and that in-situ optimization through hydrocarbon analysis may provide further enhancement in the allowable carbon concentration range.

Limits on the UV Photodecomposition of Carbonates on Mars

NASA Technical Reports Server (NTRS)

Quinn, Richard; Zent, Aaron P.; McKay, Christopher P.; DeVincenzi, Donald L. (Technical Monitor)

2002-01-01

The effect of UV (ultraviolet) light on the stability of calcium carbonate in a simulated martian atmosphere was experimentally investigated. Sample cells containing C-13 labeled calcite were irradiated with a Xe arc lamp in 10 mbar of simulated martian atmosphere and a quadrupole mass spectrometer was used to monitor the headspace gases for the production of (13)CO2. We found no experimental evidence of the UV photodecomposition of calcium carbonate in a simulated martian atmosphere. Extrapolating the lower limit of detection of our experimental system to an upper limit of carbonate decomposition on Mars yields a quantum efficiency of 3.5 x 10(exp -8) molecules/photon over the wavelength interval of 190-390 nm and a maximum UV photodecomposition rate of 1.2 x 10(exp -13) kg m(exp -2) s(exp -1) from a calcite surface. The maximum loss of bulk calcite due to this process would be 2.5 nm yr(exp -1). However, calcite is expected to be thermodynamically stable on the surface of Mars and potential UV photodecomposition reaction mechanisms indicate that while calcium carbonate may decompose under vacuum, it would be stable in a CO2 atmosphere. Given the expected stability of carbonate on Mars and our inability to detect carbonate decomposition, we conclude that it is unlikely that the apparent absence of carbonate on the martian surface is due to UV photo decomposition of calcite in the current environment.

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

PubMed Central

Mok, Jungbin; Krotkov, Nickolay A.; Arola, Antti; Torres, Omar; Jethva, Hiren; Andrade, Marcos; Labow, Gordon; Eck, Thomas F.; Li, Zhanqing; Dickerson, Russell R.; Stenchikov, Georgiy L.; Osipov, Sergey; Ren, Xinrong

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 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. PMID:27833145

Inconstant sun: how solar evolution has affected cosmic and ultraviolet radiation exposure over the history of life on Earth.

PubMed

Karam, P Andrew

2003-03-01

Four billion years ago, sea-level UV exposure was more than 400 times as intense as today, the dose from solar cosmic rays was five times present levels, and galactic cosmic rays accounted for only about 10% their current contribution to sea-level radiation doses. Exposure to cosmic radiation accounts for about 10% of natural background radiation exposure today and includes dose from galactic cosmic rays and solar charged particles. There is little exposure to ionizing wavelengths of UV due to absorption by ozone. The sun has evolved significantly over its life; in the past there were higher levels of particulate radiation and lower UV emissions from the sun, and a stronger solar wind reduced radiation dose in the inner solar system from galactic cosmic rays. Finally, since the early atmosphere contained little to no oxygen, surface levels of UV radiation were far higher in the past.

Diverse policy implications for future ozone and surface UV in a changing climate

NASA Astrophysics Data System (ADS)

Butler, A. H.; Daniel, J. S.; Portmann, R. W.; Ravishankara, A. R.; Young, P. J.; Fahey, D. W.; Rosenlof, K. H.

2016-06-01

Due to the success of the Montreal Protocol in limiting emissions of ozone-depleting substances, concentrations of atmospheric carbon dioxide, nitrous oxide, and methane will control the evolution of total column and stratospheric ozone by the latter half of the 21st century. As the world proceeds down the path of reducing climate forcing set forth by the 2015 Conference of the Parties to the United Nations Framework Convention on Climate Change (COP 21), a broad range of ozone changes are possible depending on future policies enacted. While decreases in tropical stratospheric ozone will likely persist regardless of the future emissions scenario, extratropical ozone could either remain weakly depleted or even increase well above historical levels, with diverse implication for ultraviolet (UV) radiation. The ozone layer’s dependence on future emissions of these gases creates a complex policy decision space for protecting humans and ecosystems, which includes unexpected options such as accepting nitrous oxide emissions in order to maintain historical column ozone and surface UV levels.

Systematic oxidation of polystyrene by ultraviolet-ozone, characterized by near-edge X-ray absorption fine structure and contact angle.

PubMed

Klein, Robert J; Fischer, Daniel A; Lenhart, Joseph L

2008-08-05

The process of implanting oxygen in polystyrene (PS) via exposure to ultraviolet-ozone (UV-O) was systematically investigated using the characterization technique of near-edge X-ray absorption fine structure (NEXAFS). Samples of PS exposed to UV-O for 10-300 s and washed with isopropanol were analyzed using the carbon and oxygen K-edge NEXAFS partial electron yields, using various retarding bias voltages to depth-profile the oxygen penetration into the surface. Evaluation of reference polymers provided a scale to quantify the oxygen concentration implanted by UV-O treatment. We find that ozone initially reacts with the double bonds on the phenyl rings, forming carbonyl groups, but within 1 min of exposure, the ratio of double to single oxygen bonds stabilizes at a lower value. Oxygen penetrates the film with relative ease, creating a fairly uniform distribution of oxygen within at least the first 4 nm (the effective depth probed by NEXAFS here). Before oxygen accumulates in large concentrations, however, it preferentially degrades the uppermost layer of the film by removing oxygenated low-molecular-weight oligomers. The failure to accumulate high concentrations of oxygen is seen in the nearly constant carbon edge jump, the low concentration of oxygen even at 5 min exposure (58% of that in poly(4-acetoxystyrene), the polymer with the most similarities to UV-O-treated PS), and the relatively high contact angles. At 5 min exposure the oxygen concentration contains ca. 7 atomic % oxygen. The oxygen species that are implanted consist predominantly of single O-C bonds and double O=C bonds but also include a small fraction of O-H. UV-O treatment leads a plateau after 2 min exposure in the water contact angle hysteresis, at a value of 67 +/- 2 degrees , due primarily to chemical heterogeneity. Annealing above T(g) allows oxygenated species to move short distances away from the surface but not diffuse further than 1-2 nm.

Riemann sum method for non-line-of-sight ultraviolet communication in noncoplanar geometry

NASA Astrophysics Data System (ADS)

Song, Peng; Zhou, Xianli; Song, Fei; Zhao, Taifei; Li, Yunhong

2017-12-01

The non-line-of-sight ultraviolet (UV) communication relies on the scattering common volume, however, it is difficult to carry out the triple integral operation of the scattering common volume. Based on UV single-scattering propagation theory and the spherical coordinate, we propose to use the Riemann sum method (RSM) to analyze the link path loss (PL) of UV communication system in noncoplanar geometries, and carried out related simulations. In addition, an outdoor testbed using UV light-emitting diode was set up to provide support for the validity of the RSM. When the elevation angles of the transmitter or the receiver are small, using RSM, the channel PL and temporal response of UV communication systems can be effectively and efficiently calculated. It is useful in UV embedded system design.

Resistance of a lizard (the green anole, Anolis carolinensis; Polychridae) to ultraviolet radiation-induced immunosuppression

USGS Publications Warehouse

Cope, R.B.; Fabacher, D.L.; Lieske, C.; Miller, C.A.

2001-01-01

The green anole (Anolis carolinensis) is the most northerly distributed of its Neotropical genus. This lizard avoids a winter hibernation phase by the use of sun basking behaviors. Inevitably, this species is exposed to high doses of ambient solar ultraviolet radiation (UVR). Increases in terrestrial ultraviolet-B (UV-B) radiation secondary to stratospheric ozone depletion and habitat perturbation potentially place this species at risk of UVR-induced immunosuppression. Daily exposure to subinflammatory UVR (8 kJ/m2/day UV-B, 85 kJ/m2/day ultraviolet A [UV-A]), 6 days per week for 4 weeks (total cumulative doses of 192 kJ/m2 UV-B, 2.04 × 103 kJ/m2 UV-A) did not suppress the anole's acute or delayed type hypersensitivity (DTH) response to horseshoe crab hemocyanin. In comparison with the available literature UV-B doses as low as 0.1 and 15.9 kJ/m2 induced suppression of DTH responses in mice and humans, respectively. Exposure of anoles to UVR did not result in the inhibition of ex vivo splenocyte phagocytosis of fluorescein labeled Escherichia coli or ex vivo splenocyte nitric oxide production. Doses of UV-B ranging from 0.35 to 45 kJ/m2 have been reported to suppress murine splenic/peritoneal macrophage phagocytosis and nitric oxide production. These preliminary studies demonstrate the resistance of green anoles to UVR-induced immunosuppression. Methanol extracts of anole skin contained two peaks in the ultraviolet wavelength range that could be indicative of photoprotective substances. However, the resistance of green anoles to UVR is probably not completely attributable to absorption by UVR photoprotective substances in the skin but more likely results from a combination of other factors including absorption by the cutis and absorption and reflectance by various components of the dermis.

Large enhancement of UV luminescence emission of ZnO nanoparticles by coupling excitons with Ag surface plasmons

NASA Astrophysics Data System (ADS)

Kuiri, Probodh K.; Pramanik, Subhamay

2018-04-01

For an emitter based on bandgap emission, defect mediated emission has always been considered as the most important loss. Here, a novel approach which can overcome such emission loss is proposed using films of ZnO nanoparticles (NPs) on Ag NPs embedded in silica. The effects of the size of Ag NPs on the enhancement of ultra-violet (UV) photoluminescence (PL) of ZnO NPs for such a system have been studied. For the ZnO NPs without Ag NPs, two emission bands have been seen: one in the UV region and the other one in the visible region. This UV PL emission intensity has been seen to increase significantly with a drastic reduction of the visible PL emission intensity in the case of the sample containing ZnO NPs on silica embedded Ag NPs. A linear increase in UV emission with increase in the size of Ag NPs has been found. For the largest size of Ag NPs (˜10 nm, considered in the present study), the PL emission enhancement becomes about 4 times higher than that of sample without Ag NPs. The observed enhancement of the UV PL emission was caused by coupling between spontaneous emission in ZnO and surface plasmons of Ag. The larger Ag NPs provided a larger scattering cross section in coupling surface plasmons to light leading to an increase in UV emission. Thus, it is possible to convert the useless defect emission to the useful excitonic emission with a large enhancement factor.

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

PubMed

Machida, I; Saeki, T; Nakai, S

1986-03-01

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

A Kennicutt-Schmidt relation at molecular cloud scales and beyond

NASA Astrophysics Data System (ADS)

Khoperskov, Sergey A.; Vasiliev, Evgenii O.

2017-06-01

Using N-body/gasdynamic simulations of a Milky Way-like galaxy, we analyse a Kennicutt-Schmidt (KS) relation, Σ _SFR ∝ Σ _gas^N, at different spatial scales. We simulate synthetic observations in CO lines and ultraviolet (UV) band. We adopt the star formation rate (SFR) defined in two ways: based on free fall collapse of a molecular cloud - ΣSFR, cl, and calculated by using a UV flux calibration - ΣSFR,UV. We study a KS relation for spatially smoothed maps with effective spatial resolution from molecular cloud scales to several hundred parsecs. We find that for spatially and kinematically resolved molecular clouds the Σ _{SFR, cl} ∝ σ _{gas}^N relation follows the power law with index N ≈ 1.4. Using UV flux as SFR calibrator, we confirm a systematic offset between the ΣSFR,UV and Σgas distributions on scales compared to molecular cloud sizes. Degrading resolution of our simulated maps for surface densities of gas and SFRs, we establish that there is no relation ΣSFR,UV -Σgas below the resolution ˜50 pc. We find a transition range around scales ˜50-120 pc, where the power-law index N increases from 0 to 1-1.8 and saturates for scales larger ˜120 pc. A value of the index saturated depends on a surface gas density threshold and it becomes steeper for higher Σgas threshold. Averaging over scales with size of ≳ 150 pc the power-law index N equals 1.3-1.4 for surface gas density threshold ˜5 M⊙ pc-2. At scales ≳ 120 pc surface SFR densities determined by using CO data and UV flux, ΣSFR,UV/SFR, cl, demonstrate a discrepancy about a factor of 3. We argue that this may be originated from overestimating (constant) values of conversion factor, star formation efficiency or UV calibration used in our analysis.

[Effects of different surface treatments on the zirconia-resin cement bond strength].

PubMed

Liao, Y; Liu, X Q; Chen, L; Zhou, J F; Tan, J G

2018-02-18

To evaluate the effects of different surface treatments on the shear bond strength between zirconia and resin cement. Forty zirconia discs were randomly divided into four groups (10 discs in each group) for different surface treatments: control, no surface treatment; sandblast, applied air abrasion with aluminum oxide particles; ultraviolet (UV), the zirconia sample was placed in the UV sterilizer at the bottom of the UV lamp at 10 mm, and irradiated for 48 h; cold plasma, the discs were put in the cold plasma cabinet with the cold plasma generated from the gas of He for 30 s. Specimens of all the groups were surface treated prior to cementation with Panavia F 2.0 cement. The surface morphology and contact angle of water were measured. The shear bond strengths were tested and the failure modes were examined with a stereomicroscope. Surface morphology showed no difference between the UV/cold plasma group and the control group. Sandblasted zirconia displayed an overall heterogeneous distribution of micropores. The contact angle of the control group was 64.1°±2.0°. After sandblasting, UV irradiation and cold plasma exposure, the values significantly decreased to 48.8°±2.6°, 27.1°±3.6° and 32.0°±3.3°. The values of shear bond strength of the specimens with sandblasted (14.82±2.01) MPa were higher than those with no treatment (9.41±1.07) MPa with statistically significant difference (P<0.05). The values of shear bond strength of the specimens with UV irradiation (10.02±0.64) MPa were higher than those with no treatment (9.41±1.07) MPa, but without statistically significant difference (P>0.05). The values of cold plasma group (18.34±3.05) MPa were significantly higher than those of control group (9.41±1.07) MPa, even more than those with sandblast(14.82±2.01) MPa (P<0.05). X-ray photoelectron spectroscopy (XPS) showed increase in oxygen (O) and decrease in carbon (C) elements after UV and cold plasma treatment. The surface C/O ratio also decreased after UV and cold plasma treatment. Zirconia specimens treated with UV and cold plasma could significantly improve the hydrophilicity. The surface morphology was unaffected by the UV irradiation and cold plasma treatments. The improvements of ziconia shear bond strength were slight in UV group without statistically significant difference. Cold plasma treatment significantly improved the shear bond strength between zirconia and resin cement.

All-femtosecond laser-assisted in situ keratomileusis

NASA Astrophysics Data System (ADS)

Gabryte, Egle; Danieliene, Egle; Vaiceliunaite, Agne; Ruksenas, Osvaldas; Vengris, Mikas; Danielius, Romualdas

2013-03-01

We present a femtosecond solid-state Yb:KGW laser system capable of performing the complete laser-assisted in situ keratomileusis (LASIK) ophthalmic procedure. The fundamental infrared radiation (IR) is used to create the corneal flap, and subsequently the corneal stromal ablation is performed using the ultraviolet (UV) pulses of the fifth harmonic. The heating of cornea, ablated surface quality, and healing outcomes of the surgeries performed using the femtosecond laser system are investigated by both ex vivo and in vivo experiments and compared to the results of conventional clinical ArF excimer laser application. The results of this research indicate the feasibility of clinical application of femtosecond UV lasers for LASIK procedure.

Effect of pentacene/Ag anode buffer and UV-ozone treatment on durability of small-molecule organic solar cells

NASA Astrophysics Data System (ADS)

Inagaki, S.; Sueoka, S.; Harafuji, K.

2017-06-01

Three surface modifications of indium tin oxide (ITO) are experimentally investigated to improve the performance of small-molecule organic solar cells (OSCs) with an ITO/anode buffer layer (ABL)/copper phthalocyanine (CuPc)/fullerene/bathocuproine/Ag structure. An ultrathin Ag ABL and ultraviolet (UV)-ozone treatment of ITO independently improve the durability of OSCs against illumination stress. The thin pentacene ABL provides good ohmic contact between the ITO and the CuPc layer, thereby producing a large short-circuit current. The combined use of the abovementioned three modifications collectively achieves both better initial performance and durability against illumination stress.

Growth of a mat-forming photograph in the presence of UV radiation

NASA Technical Reports Server (NTRS)

Pierson, Beverly K.; Ruff, A. L.

1989-01-01

Knowledge of the survival and growth of microorganisms in the presence of ultraviolet radiation is important for understanding the potential for life to exist in environments exposed to high fluxes of UV radiation. The growth of a mat-forming phototrophic prokaryote, Chloroflexus aurantiacus, was examined in the presence of continuous high UV irradiation under otherwise optimal growth conditions. Evidence was sought for an intrinsic ability to grow in the presence of UV radiation in a carefully chosen organism known to be unusually resistant to UV radiation, of ancient lineage among the phototrophs, to resemble ancient microfossils from the Precambrian, and to be a mat-former. It was assumed that even a high intrinsic UV resistance would be inadequate for survival and growth in the presence of very high UV fluxes, and iron (Fe3+) was selected as a common, abundant UV-absorbing substance that might protest microorganisms growing in or under iron-bearing sediments. The effectiveness of Fe(3+) was tested as a UV protective agent at low concentrations in thin layers. It was concluded that intrinsic UV resistance in some organisms may account for growth, not just survival, of these organisms when exposed to high UV fluxes under otherwise optimal growth conditions in an anoxic environment. It was also concluded that Fe(3+) bearing sediments of 1 mm or less in thickness may provide an adequate shield against high UV fluxes permitting the growth of microorganisms just below their surface. As long as growth conditions were met, then the evolution and development of microorganisms would not be hampered by high UV fluxes impinging upon the surface of iron-bearing sediments.

Significant Enhancement of MgZnO Metal-Semiconductor-Metal Photodetectors via Coupling with Pt Nanoparticle Surface Plasmons

NASA Astrophysics Data System (ADS)

Guo, Zexuan; Jiang, Dayong; Hu, Nan; Yang, Xiaojiang; Zhang, Wei; Duan, Yuhan; Gao, Shang; Liang, Qingcheng; Zheng, Tao; Lv, Jingwen

2018-06-01

We proposed and demonstrated MgZnO metal-semiconductor-metal (MSM) ultraviolet photodetectors (UV) assisted with surface plasmons (SPs) prepared by the radio frequency magnetron sputtering deposition method. After the decoration of their surface with Pt nanoparticles (NPs), the responsivity of all the electrode spacing (3, 5, and 8 μm) photodetectors were enhanced dramatically; to our surprise, comparing with them the responsivity of larger spacing sample, more SPs were gathered which are smaller than others in turn. A physical mechanism focused on SPs and depletion width is given to explain the above results.

Nanotechnology in lithium niobate for integrated optic frequency conversion in the UV

NASA Astrophysics Data System (ADS)

Busacca, Alessandro C.; Santini, Claudia; Oliveri, Luigi; Riva-Sanseverino, Stefano; Parisi, Antonino; Cino, Alfonso C.; Assanto, Gaetano

2017-11-01

In the domain of Earth Explorer satellites nanoengineered nonlinear crystals can optimize UV tunable solid-state laser converters. Lightweight sources can be based on Lithium Niobate (LN) domain engineering by electric field poling and guided wave interactions. In this Communication we report the preliminary experimental results and the very first demonstration of UltraViolet second-harmonic generation by first-order quasi-phase-matching in a surface-periodically-poled proton-exchanged LN waveguide. The pump source was a Ti-Sapphire laser with a tunability range of 700- 980 nm and a 40 GHz linewidth. We have measured UV continuous-wave light at 390 nm by means of a lock-in amplifier and of a photodiode with enhanced response in the UV. Measured conversion efficiency was about 1%W-1cm-2. QPM experiments show good agreement with theory and pave the way for a future implementation of the technique in materials less prone to photorefractive damage and wider transparency in the UV, such as Lithium Tantalate.

A ZnO nanowire-based photo-inverter with pulse-induced fast recovery.

PubMed

Raza, Syed Raza Ali; Lee, Young Tack; Hosseini Shokouh, Seyed Hossein; Ha, Ryong; Choi, Heon-Jin; Im, Seongil

2013-11-21

We demonstrate a fast response photo-inverter comprised of one transparent gated ZnO nanowire field-effect transistor (FET) and one opaque FET respectively as the driver and load. Under ultraviolet (UV) light the transfer curve of the transparent gate FET shifts to the negative side and so does the voltage transfer curve (VTC) of the inverter. After termination of UV exposure the recovery of photo-induced current takes a long time in general. This persistent photoconductivity (PPC) is due to hole trapping on the surface of ZnO NWs. Here, we used a positive voltage short pulse after UV exposure, for the first time resolving the PPC issue in nanowire-based photo-detectors by accumulating electrons at the ZnO/dielectric interface. We found that a pulse duration as small as 200 ns was sufficient to reach a full recovery to the dark state from the UV induced state, realizing a fast UV detector with a voltage output.

Measurement Variation and the Factors Influencing the UV Index

ERIC Educational Resources Information Center

Downs, Nathan; Parisi, Alfio; McDonnell, Brendan; Thornton, Peter

2008-01-01

The article presents a technique to measure the ultraviolet index using a personal hand-held ultraviolet meter to illustrate concepts of physics. Measurements of the erythemally effective (sun-burning) direct solar beam, diffuse skylight, and total global ultraviolet irradiance are converted to daily ultraviolet index measurements. Daily…

Conformationally resolved spectroscopy of jet-cooled methacetin

NASA Astrophysics Data System (ADS)

Moon, Cheol Joo; Ahn, Ahreum; Min, Ahreum; Seong, Yeon Guk; Kim, Ju Hyun; Choi, Myong Yong

2017-11-01

The excitation spectra of jet-cooled methacetin (MA) have been measured using a combination of mass-selected resonant two-photon ionization and ultraviolet-ultraviolet hole-burning (UV-UV HB) spectroscopy in the gas phase. Four different UV-UV HB spectra originating from two conformers of MA (syn- and anti-MA) with their fundamental and hot transitions have been obtained. IR-dip spectroscopy has conclusively confirmed the coexistence of the two conformers with the aid of theoretical calculations. Vibronic band assignments in the low frequency region caused by internal methyl group rotation in the methyl-capped peptide group, which originate from the 1e rotational level, are presented.

Replicated mesocosm study on the role of natural ultraviolet radiation in high CDOM, shallow lakes.

PubMed

Pérez, A Patricia; Diaz, Mónica M; Ferraro, Marcela A; Cusminsky, Gabriela C; Zagarese, Horacio E

2003-02-01

The role of ultraviolet radiation on shallow, high CDOM (colored dissolved organic matter) lakes was investigated during two consecutive summers (1999 and 2000) in replicated mesocosms (rectangular fiberglass tanks). Each tank (volume: 300 L; depth: 40 cm) was covered with a layer (approximately 3 cm) of sediment from lake El Toro (40 degrees 14' S; 70 degrees 22' W) and filled with filtered water. The experimental design consisted of two treatments: full natural radiation (UV-exposed) and natural radiation without ultraviolet radiation (UV-shielded). UV-exposed and UV-shielded treatments differed in most studied variables as revealed by repeated measures ANOVA. UV-exposed tanks displayed lower CDOM levels (dissolved absorbance) of lower average molecular size (absorbance ratio between 250 and 365 nm), higher bacterial biomass, and lower chlorophyll a concentration. The effect on consumers (rotifers and crustaceans) was less noticeable. The results are consistent with UV stimulation of bacteria production mediated by higher rates of CDOM photobleaching, and the photoinhibition of planktonic algae. Thus, a major effect of UVR in shallow, high CDOM ecosystems appears to be the stimulation of heterotrophic pathways and a simultaneous inhibition of photoautotrophs.

Calculating Solar Ultraviolet Irradiation Of The Human Cornea And Corresponding Required Sunglass Lens Transmittances

NASA Astrophysics Data System (ADS)

Hoover, Herbert L.; Marsaud, Serge G.

1986-05-01

Tinted ophthalmic lenses are used primarily for eye comfort in a brightly lit environment. An ancillary benefit is the attenuation of ultraviolet radiation. Some national product standards specify quantitative limits for ultraviolet transmittances. Such limits ought to be founded on quantitative estimates of solar irradiances of ocular tissues, with actinic effectiveness taken into account. We use the equations of Green and coworkers for direct and diffuse solar irradiance at the earth's surface to calculate average sky and ground spectral radiances. We use the geometric factors derived by us for the coupling of radiation from these sources to the human cornea. Actinically weighted corneal spectral irradiances integrated over wavelength and time yield peak irradiances and accumulated exposure doses that are compared with recommended exposure limits. This provides the maximal effective ultraviolet transmittances of tinted ophthalmic lenses such that these exposure limits will not be exceeded in the selected exposure environment. The influences on corneal irradiation of such exposure parameters as solar zenith angle, altitude of the exposure site, characteristics of atmospheric aerosols, and ground reflectances are illustrated. The relationships between the effective transmittance (which is a function of the environmental radiation and any actinicweighting function) and readily determined characteristics of the lens itself, viz., its mean transmittance, and a selected spectral transmittance, are derived for three lens transmittance curves. Limits of lens transmittance for the UV-B and UV-A wavelength regions are presented for several representative exposure sites in Europe and the U.S.A.

Solutions Network Formulation Report. NASA's Potential Contributions for Using Solar Ultraviolet Radiation in Conjunction with Photocatalysis for Urban Air Pollution Mitigation and Increasing Air Quality

NASA Technical Reports Server (NTRS)

Underwood, Lauren; Ryan, Robert E.

2007-01-01

This Candidate Solution is based on using NASA Earth science research on atmospheric ozone and aerosols data as a means to predict and evaluate the effectiveness of photocatalytically created surfaces (building materials like glass, tile and cement) for air pollution mitigation purposes. When these surfaces are exposed to near UV light, organic molecules, like air pollutants and smog precursors, will degrade into environmentally friendly compounds. U.S. EPA (Environmental Protection Agency) is responsible for forecasting daily air quality by using the Air Quality Index (AQI) that is provided by AIRNow. EPA is partnered with AIRNow and is responsible for calculating the AQI for five major air pollutants that are regulated by the Clean Air Act. In this Solution, UV irradiance data acquired from the satellite mission Aura and the OMI Surface UV algorithm will be used to help understand both the efficacy and efficiency of the photocatalytic decomposition process these surfaces facilitate, and their ability to reduce air pollutants. Prediction models that estimate photocatalytic function do not exist. NASA UV irradiance data will enable this capability, so that air quality agencies that are run by state and local officials can develop and implement programs that utilize photocatalysis for urban air pollution control and, enable them to make effective decisions about air pollution protection programs.

Remote sensing of the magnetic moment of uranus: predictions for voyager.

PubMed

Hill, T W; Dessler, A J

1985-03-22

Power is supplied to a planet's magnetosphere from the kinetic energy of planetary spin and the energy flux of the impinging solar wind. A fraction of this power is available to drive numerous observable phenomena, such as polar auroras and planetary radio emissions. In this report our present understanding of these power transfer mechanisms is applied to Uranus to make specific predictions of the detectability of radio and auroral emissions by the planetary radio astronomy (PRA) and ultraviolet spectrometer (UVS) instruments aboard the Voyager spacecraft before its encounter with Uranus at the end of January 1986. The power available for these two phenomena is (among other factors) a function of the magnetic moment of Uranus. The date of earliest detectability also depends on whether the predominant power source for the magnetosphere is planetary spin or solar wind. The magnetic moment of Uranus is derived for each power source as a function of the date of first detection of radio emissions by the PRA instrument or auroral emissions by the UVS instrument. If we accept the interpretation of ultraviolet observations now available from the Earth-orbiting International Ultraviolet Explorer satellite, Uranus has a surface magnetic field of at least 0.6 gauss, and more probably several gauss, making it the largest or second-largest planetary magnetic field in the solar system.

Multilength Scale Patterning of Functional Layers by Roll-to-Roll Ultraviolet-Light-Assisted Nanoimprint Lithography.

PubMed

Leitgeb, Markus; Nees, Dieter; Ruttloff, Stephan; Palfinger, Ursula; Götz, Johannes; Liska, Robert; Belegratis, Maria R; Stadlober, Barbara

2016-05-24

Top-down fabrication of nanostructures with high throughput is still a challenge. We demonstrate the fast (>10 m/min) and continuous fabrication of multilength scale structures by roll-to-roll UV-nanoimprint lithography on a 250 mm wide web. The large-area nanopatterning is enabled by a multicomponent UV-curable resist system (JRcure) with viscous, mechanical, and surface properties that are tunable over a wide range to either allow for usage as polymer stamp material or as imprint resist. The adjustable elasticity and surface chemistry of the resist system enable multistep self-replication of structured resist layers. Decisive for defect-free UV-nanoimprinting in roll-to-roll is the minimization of the surface energies of stamp and resist, and the stepwise reduction of the stiffness from one layer to the next is essential for optimizing the reproduction fidelity especially for nanoscale features. Accordingly, we demonstrate the continuous replication of 3D nanostructures and the high-throughput fabrication of multilength scale resist structures resulting in flexible polyethylenetherephtalate film rolls with superhydrophobic properties. Moreover, a water-soluble UV-imprint resist (JRlift) is introduced that enables residue-free nanoimprinting in roll-to-roll. Thereby we could demonstrate high-throughput fabrication of metallic patterns with only 200 nm line width.

Effects of argon sputtering and UV-ozone radiation on the physico-chemical surface properties of ITO

NASA Astrophysics Data System (ADS)

Che, Hui; El Bouanani, M.

2018-01-01

X-ray photoelectron spectroscopy (XPS) and Ultraviolet Photoelectron Spectroscopy (UPS) were used to evaluate and determine the effects of 1 KeV Ar+ irradiation (sputtering) on the surface chemical composition and work function of Indium Thin Oxide (ITO). While Ar+ sputtering removes carbon-based surface contaminants, it also modifies the Sn-rich surface of ITO and leads to a reduction of the oxidation state of Sn from Sn4+ to Sn2+. The decrease in the work function of ITO is directly correlated to the decrease of Sn atomic concentration in the Sn-rich top surface layer and the reduction of the oxidation state of surface Sn.

The effects of simulated solar UVB radiation on early developmental stages of the Northwestern Salamander (Ambystoma gracile) from three lakes

USGS Publications Warehouse

Calfee, Robin D.; Little, Edward E.; Pearl, Christopher A.; Hoffman, Robert L.

2010-01-01

Solar ultraviolet radiation (UV) has received much attention as a factor that could play a role in amphibian population declines. UV can be hazardous to some amphibians, but the resultant effects depend on a variety of environmental and behavioral factors. In this study, the potential effects of UV on the Northwestern Salamander, Ambystoma gracile, from three lakes were assessed in the laboratory using a solar simulator. We measured the survival of embryos and the survival and growth of larvae exposed to four UV treatments in controlled laboratory studies, the UV absorbance of egg jelly, oviposition depths in the lakes, and UV absorbance in water samples from the three lakes. Hatching success of embryos decreased in the higher UV treatments as compared to the control treatments, and growth of surviving larvae was significantly reduced in the higher UVB irradiance treatments. The egg jelly exhibited a small peak of absorbance within the UVB range (290–320 nm). The magnitude of UV absorbance differed among egg jellies from the three lakes. Oviposition depths at the three sites averaged 1.10 m below the water surface. Approximately 66% of surface UVB radiation was attenuated at 10-cm depth in all three lakes. Results of this study indicate that larvae may be sensitive to UVB exposure under laboratory conditions; however, in field conditions the depths of egg deposition in the lakes, absorbance of UV radiation by the water column, and the potential for behavioral adjustments may mitigate severe effects of UV radiation.

Effects of simulated solar UVB radiation on early developmental stages of the northwestern salamander (Ambystoma gracile) from three lakes

USGS Publications Warehouse

Calfee, R.D.; Little, E.E.; Pearl, C.A.; Hoffman, R.L.

2010-01-01

Solar ultraviolet radiation (UV) has received much attention as a factor that could play a role in amphibian population declines. UV can be hazardous to some amphibians, but the resultant effects depend on a variety of environmental and behavioral factors. In this study, the potential effects of UV on the Northwestern Salamander, Ambystoma gracile, from three lakes were assessed in the laboratory using a solar simulator. We measured the survival of embryos and the survival and growth of larvae exposed to four UV treatments in controlled laboratory studies, the UV absorbance of egg jelly, oviposition depths in the lakes, and UV absorbance in water samples from the three lakes. Hatching success of embryos decreased in the higher UV treatments as compared to the control treatments, and growth of surviving larvae was significantly reduced in the higher UVB irradiance treatments. The egg jelly exhibited a small peak of absorbance within the UVB range (290-320 nm). The magnitude of UV absorbance differed among egg jellies from the three lakes. Oviposition depths at the three sites averaged 1.10 m below the water surface. Approximately 66 of surface UVB radiation was attenuated at 10-cm depth in all three lakes. Results of this study indicate that larvae may be sensitive to UVB exposure under laboratory conditions; however, in field conditions the depths of egg deposition in the lakes, absorbance of UV radiation by the water column, and the potential for behavioral adjustments may mitigate severe effects of UV radiation. Copyright 2010 Society for the Study of Amphibians and Reptiles.

High-throughput ultraviolet photoacoustic microscopy with multifocal excitation

NASA Astrophysics Data System (ADS)

Imai, Toru; Shi, Junhui; Wong, Terence T. W.; Li, Lei; Zhu, Liren; Wang, Lihong V.

2018-03-01

Ultraviolet photoacoustic microscopy (UV-PAM) is a promising intraoperative tool for surgical margin assessment (SMA), one that can provide label-free histology-like images with high resolution. In this study, using a microlens array and a one-dimensional (1-D) array ultrasonic transducer, we developed a high-throughput multifocal UV-PAM (MF-UV-PAM). Our new system achieved a 1.6 ± 0.2 μm lateral resolution and produced images 40 times faster than the previously developed point-by-point scanning UV-PAM. MF-UV-PAM provided a readily comprehensible photoacoustic image of a mouse brain slice with specific absorption contrast in ˜16 min, highlighting cell nuclei. Individual cell nuclei could be clearly resolved, showing its practical potential for intraoperative SMA.

Ultraviolet B-Sensitive Rice Cultivar Deficient in Cyclobutyl Pyrimidine Dimer Repair.

PubMed Central

Hidema, J.; Kumagai, T.; Sutherland, J. C.; Sutherland, B. M.

1997-01-01

Repair of cyclobutyl pyrimidine dimers (CPDs) in DNA is essential in most organisms to prevent biological damage by ultraviolet (UV) light. In higher plants tested thus far, UV-sensitive strains had higher initial damage levels or deficient repair of nondimer DNA lesions but normal CPD repair. This suggested that CPDs might not be important for biological lesions. The photosynthetic apparatus has also been proposed as a critical target. We have analyzed CPD induction and repair in the UV-sensitive rice (Oryza sativa L.) cultivar Norin 1 and its close relative UV-resistant Sasanishiki using alkaline agarose gel electrophoresis. Norin 1 is deficient in cyclobutyl pyrimidine dimer photoreactivation and excision; thus, UV sensitivity correlates with deficient dimer repair. PMID:12223592

UV clothing and skin cancer.

PubMed

Tarbuk, Anita; Grancarić, Ana Marija; Situm, Mirna; Martinis, Mladen

2010-04-01

Skin cancer incidence in Croatia is steadily increasing in spite of public and governmental permanently measurements. It is clear that will soon become a major public health problem. The primary cause of skin cancer is believed to be a long exposure to solar ultraviolet (UV) radiation. The future designers of UV protective materials should be able to block totally the ultraviolet radiation. The aim of this paper is to present results of measurements concerning UV protecting ability of garments and sun-screening textiles using transmission spectrophotometer Cary 50 Solarscreen (Varian) according to AS/NZS 4399:1996; to show that standard clothing materials are not always adequate to prevent effect of UV radiation to the human skin; and to suggest the possibilities for its improvement for this purpose.

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

PubMed

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

2014-09-01

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

AlGaN Ultraviolet Detectors for Dual-Band UV Detection

NASA Technical Reports Server (NTRS)

Miko, Laddawan; Franz, David; Stahle, Carl M.; Yan, Feng; Guan, Bing

2010-01-01

This innovation comprises technology that has the ability to measure at least two ultraviolet (UV) bands using one detector without relying on any external optical filters. This allows users to build a miniature UVA and UVB monitor, as well as to develop compact, multicolor imaging technologies for flame temperature sensing, air-quality control, and terrestrial/counter-camouflage/biosensing applications.

Ultraviolet-B radiation in a row-crop canopy: an extended 1-D model

Treesearch

Wei Gao; Richard H. Grant; Gordon M. Heisler; James R. Slusser

2003-01-01

A decrease in stratospheric ozone may result in a serious threat to plants, since biologically active short-wavelength ultraviolet-B (UV-B 280-320 nm) radiation will increase even with a relatively small decrease in ozone. Numerous investigations have demonstrated that the effect of UV-B enhancements on plants includes reduction in grain yield, alteration in species...

A geometric ultraviolet-B radiation transfer model applied to vegetation canopies

Treesearch

Wei Gao; Richard H. Grant; Gordon M. Heisler; James R. Slusser

2002-01-01

The decrease in stratospheric ozone (O3) has prompted continued efforts to assess the potential damage to plant and animal life due to enhanced levels of solar ultraviolet (UV)-B (280-320 nm) radiation. The objective of this study was to develop and evaluate an analytical model to simulate the UV-B irradiance loading on horizontal below- canopy...

Disinfection of Mycobacterium avium subspecies hominissuis in drinking tap water using ultraviolet germicidal irradiation.

PubMed

Schiavano, Giuditta Fiorella; De Santi, Mauro; Sisti, Maurizio; Amagliani, Giulia; Brandi, Giorgio

2017-09-13

Nontuberculous mycobacteria are resistant to conventional water treatments, and are opportunistic human pathogen, particularly in hospitalized patients. The aim of this investigation was to assess the effectiveness of an ultraviolet UV-C lamp treatment against Mycobacterium avium subspecies hominissuis in drinking tap water. Ultraviolet treatments (0-192 mJ/cm 2 ) were performed using UV lamp immerged onto cylindrical glass tubes containing artificially contaminated water. The results showed that susceptibility to UV varied considerably according to the strains and the diameter of the tube. With a dose of 32 mJ/cm 2 , a significant inactivation (p < .05) of 3 log (99.9%) or more was obtained in only 5 of the 14 strains. To obtain a complete inactivation of all strains an irradiation of 192 mJ/cm 2 was needed, a dose that is much higher than the limits recommended by the international standards for UV disinfection of drinking water. In conclusion, it may be difficult to standardize a UV dose for the elimination of waterborne mycobacteria.

Photomorphogenic responses to ultraviolet-B light.

PubMed

Jenkins, Gareth I

2017-11-01

Exposure to ultraviolet B (UV-B) light regulates numerous aspects of plant metabolism, morphology and physiology through the differential expression of hundreds of genes. Photomorphogenic responses to UV-B are mediated by the photoreceptor UV RESISTANCE LOCUS8 (UVR8). Considerable progress has been made in understanding UVR8 action: the structural basis of photoreceptor function, how interaction with CONSTITUTIVELY PHOTOMORPHOGENIC 1 initiates signaling and how REPRESSOR OF UV-B PHOTOMORPHOGENESIS proteins negatively regulate UVR8 action. In addition, recent research shows that UVR8 mediates several responses through interaction with other signaling pathways, in particular auxin signaling. Nevertheless, many aspects of UVR8 action remain poorly understood. Most research to date has been undertaken with Arabidopsis, and it is important to explore the functions and regulation of UVR8 in diverse plant species. Furthermore, it is essential to understand how UVR8, and UV-B signaling in general, regulates processes under natural growth conditions. Ultraviolet B regulates the expression of many genes through UVR8-independent pathways, but the activity and importance of these pathways in plants growing in sunlight are poorly understood. © 2017 John Wiley & Sons Ltd.

Visible-blind ultraviolet photodetectors on porous silicon carbide substrates

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

Naderi, N.; Hashim, M.R., E-mail: roslan@usm.my

2013-06-01

Highlights: • Highly reliable UV detectors are fabricated on porous silicon carbide substrates. • The optical properties of samples are enhanced by increasing the current density. • The optimized sample exhibits enhanced sensitivity to the incident UV radiation. - Abstract: Highly reliable visible-blind ultraviolet (UV) photodetectors were successfully fabricated on porous silicon carbide (PSC) substrates. High responsivity and high photoconductive gain were observed in a metal–semiconductor–metal ultraviolet photodetector that was fabricated on an optimized PSC substrate. The PSC samples were prepared via the UV-assisted photo-electrochemical etching of an n-type hexagonal silicon carbide (6H-SiC) substrate using different etching current densities. Themore » optical results showed that the current density is an outstanding etching parameter that controls the porosity and uniformity of PSC substrates. A highly porous substrate was synthesized using a suitable etching current density to enhance its light absorption, thereby improving the sensitivity of UV detector with this substrate. The electrical characteristics of fabricated devices on optimized PSC substrates exhibited enhanced sensitivity and responsivity to the incident radiation.« less

Deactivation of photocatalytically active ZnO nanoparticle and enhancement of its compatibility with organic compounds by surface-capping with organically modified silica

NASA Astrophysics Data System (ADS)

Cao, Zhi; Zhang, Zhijun

2011-02-01

Tetraethyl orthosilicate (TEOS) and dimethyldiethoxysilane (DEDMS) were used as co-precursors to prepare organically modified silica (ormosil) via sol-gel process. The resultant ormosil was adopted for surface-capping of ZnO nanoparticle, where methyl (organic functional group) and silica (inorganic component) were simultaneously introduced onto the surface of the nanoparticles for realizing dual surface-modification. The ormosil-capped ZnO nanoparticle showed strong hydrophobicity and good compatibility with organic phases, as well as effectively decreased photocatalytic activity and almost unchanged ultraviolet (UV)-shielding ability. More importantly, the comprehensive properties of ormosil-capped ZnO nanoparticle could be manipulated by adjusting the molar ratio of TEOS to DEDMS during sol-gel process. This should help to open a wider window to better utilizing the unique and highly attractive properties such as high UV-shielding ability and high-visible light transparency of ZnO nanoparticle in sunscreen cosmetics.

An estimation methode for measurement of ultraviolet radiation during nondestructive testing

NASA Astrophysics Data System (ADS)

Hosseinipanah, M.; Movafeghi, A.; Farvadin, D.

2018-04-01

Dye penetrant testing and magnetic particle testing are among conventional NDT methods. For increased sensitivity, fluorescence dyes and particles can be used with ultraviolet (black) lights. UV flaw detection lights have different spectra. With the help of photo-filters, the output lights are transferred to UV-A and visible zones. UV-A light can be harmful to human eyes in some conditions. In this research, UV intensity and spectrum were obtained by a Radio-spectrometer for two different UV flaw detector lighting systems. According to the standards such as ASTM E709, UV intensity must be at least 10 W/m2 at a distance of 30 cm. Based on our measurements; these features not achieved in some lamps. On the other hand, intensity and effective intensity of UV lights must be below the some limits for prevention of unprotected eye damage. NDT centers are usually using some type of UV measuring devices. A method for the estimation of effective intensity of UV light has been proposed in this research.